Relationship between domestic smoking and metals and rare earth elements concentration in indoor PM2.5.

PubMed

Drago, Gaspare; Perrino, Cinzia; Canepari, Silvia; Ruggieri, Silvia; L'Abbate, Luca; Longo, Valeria; Colombo, Paolo; Frasca, Daniele; Balzan, Martin; Cuttitta, Giuseppina; Scaccianoce, Gianluca; Piva, Giuseppe; Bucchieri, Salvatore; Melis, Mario; Viegi, Giovanni; Cibella, Fabio; Balzan, Martin; Bilocca, David; Borg, Charles; Montefort, Stephen; Zammit, Christopher; Bucchieri, Salvatore; Cibella, Fabio; Colombo, Paolo; Cuttitta, Giuseppina; Drago, Gaspare; Ferrante, Giuliana; L'Abbate, Luca; Grutta, Stefania La; Longo, Valeria; Melis, Mario R; Ruggieri, Silvia; Viegi, Giovanni; Minardi, Remo; Piva, Giuseppe; Ristagno, Rosaria; Rizzo, Gianfranco; Scaccianoce, Gianluca

2018-04-16

Cigarette smoke is the main source of indoor chemical and toxic elements. Cadmium (Cd), Thallium (Tl), Lead (Pb) and Antimony (Sb) are important contributors to smoke-related health risks. Data on the association between Rare Earth Elements (REE) Cerium (Ce) and Lanthanum (La) and domestic smoking are scanty. To evaluate the relationship between cigarette smoke, indoor levels of PM 2.5 and heavy metals, 73 children were investigated by parental questionnaire and skin prick tests. The houses of residence of 41 "cases" and 32 "controls" (children with and without respiratory symptoms, respectively) were evaluated by 48-h PM 2.5 indoor/outdoor monitoring. PM 2.5 mass concentration was determined by gravimetry; the extracted and mineralized fractions of elements (As, Cd, Ce, La, Mn, Pb, Sb, Sr, Tl) were evaluated by ICP-MS. PM 2.5 and Ce, La, Cd, and Tl indoor concentrations were higher in smoker dwellings. When corrected for confounding factors, PM 2.5 , Ce, La, Cd, and Tl were associated with more likely presence of respiratory symptoms in adolescents. We found that: i) indoor smoking is associated with increased levels of PM 2.5 , Ce, La, Cd, and Tl and ii) the latter with increased presence of respiratory symptoms in children. Copyright © 2018 Elsevier Inc. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2017-04-01

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

Determination of Rare Earth Elements in Geological Samples Using Laser-Induced Breakdown Spectroscopy (LIBS).

PubMed

Bhatt, Chet R; Jain, Jinesh C; Goueguel, Christian L; McIntyre, Dustin L; Singh, Jagdish P

2018-01-01

Laser-induced breakdown spectroscopy (LIBS) was used to detect rare earth elements (REEs) in natural geological samples. Low and high intensity emission lines of Ce, La, Nd, Y, Pr, Sm, Eu, Gd, and Dy were identified in the spectra recorded from the samples to claim the presence of these REEs. Multivariate analysis was executed by developing partial least squares regression (PLS-R) models for the quantification of Ce, La, and Nd. Analysis of unknown samples indicated that the prediction results of these samples were found comparable to those obtained by inductively coupled plasma mass spectrometry analysis. Data support that LIBS has potential to quantify REEs in geological minerals/ores.

Standard reference water samples for rare earth element determinations

USGS Publications Warehouse

Verplanck, P.L.; Antweiler, Ronald C.; Nordstrom, D. Kirk; Taylor, Howard E.

2001-01-01

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

Rare earth elements: end use and recyclability

USGS Publications Warehouse

Goonan, Thomas G.

2011-01-01

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

Rare earth element content of cryptocrystalline magnesites of Konya, Turkey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zedef, Veysel, E-mail: vzedef@selcuk.edu.tr; Russell, Michael

We examined the rare earth element content of several cryptocrystalline magnesites as well as hydromagnesite, host rock serpentinites, lake water and hot spring water from Turkey. Southwestern Turkey hosts cryptocrystalline magnesites, sedimentary magnesites with presently forming, biologically mediated hydromagnesites and travertines. Our results show the REE content of the minerals, rocks and waters are well below detection limits. One hydromagnesite sample from Lake Salda has slightly high La (2.38ppb), Ce (3.91 ppb) and Nd (1.68 ppb) when compared to other samples, but these are also still below detection limits of the method we followed.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alam, Aftab; Khan, Mahmud; McCallum, R. W.

2013-01-28

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

Mineral resource of the month: rare earth elements

USGS Publications Warehouse

,

2011-01-01

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

Structure determination and characterization of two rare-earth molybdenum borate compounds: LnMoBO(6) (Ln = La, Ce).

PubMed

Zhao, Dan; Cheng, Wen-Dan; Zhang, Hao; Hang, Shu-Ping; Fang, Ming

2008-07-28

The structural, optical, and electronic properties of two rare-earth molybdenum borate compounds, LnMoBO(6) (Ln = La, Ce), have been investigated by means of single-crystal X-ray diffraction, elemental analyses, and spectral measurements, as well as calculations of energy band structures, density of states, and optical response functions by the density functional method. The title compounds, which crystallize in monoclinic space group P2(1)/c, possess a similar network of interconnected [Ce(2)(MoO(4))(2)](2+) chains and [BO(2)](-) wavy chains. Novel 1D molybdenum oxide chains are contained in their three-dimensional (3D) networks. The calculated results of crystal energy band structure by the density functional theory (DFT) method show that the solid-state compound LaMoBO(6) is a semiconductor with indirect band gaps.

Rare earth and precious elements in the urban sewage sludge and lake surface sediments under anthropogenic influence in the Republic of Benin.

PubMed

Yessoufou, Arouna; Ifon, Binessi Edouard; Suanon, Fidèle; Dimon, Biaou; Sun, Qian; Dedjiho, Comlan Achille; Mama, Daouda; Yu, Chang-Ping

2017-11-09

Nowadays, sewage sludge and water bodies are subjected to heavy pollution due to rapid population growth and urbanization. Heavy metal pollution represents one of the main challenges threatening our environment and the ecosystem. The present work aims to evaluate the contamination state of the sewage sludge and lake sediments in the Republic of Benin. Twenty metallic elements including 15 rare earth elements (Eu, Sb, Cs, Nd, Pr, Gd, La, Ce, Tb, Sm, Dy, Ho, Eu, Yb, and Lu) and five precious elements (Ag, Au, Pd, Pt, and Ru) were investigated using inductive plasma-mass spectrometry. Results showed broad range concentrations of the elements. Ce, La, and Nd were present in both sediments and sewage sludge at concentrations ranging 5.80-41.30 mg/kg dry matter (DM), 3.23-15.60 mg/kg DM, and 2.74-19.26 mg/kg DM, respectively. Pr, Sm, Gd, Tb, Dy, Eu, Er, Yb, Cs, Ho, and Tm concentrations were lower (0.02-5.94 mg/kg DM). Among precious elements, Ag was detected at the highest concentration in all sites (0.43-4.72 mg/kg DM), followed by Pd (0.20-0.57 mg/kg DM) and Au (0.01-0.57 mg/kg DM). Ru and Pt concentrations were < 0.20 mg/kg DM in all samples. Pollution indices and enrichment factor indicated a strong to severe enrichment of the elements, mainly Ce and precious elements in both sediments and sewage sludge. This revealed a growing anthropogenic input which was also implied by principal component analysis. The evaluation of pollution loading index (PLI) indicated a moderate to strong contamination (0.12 ≤ PLI ≤ 0.58; 37 ≤ PLI ≤ 114, respectively, for rare earth elements and precious elements), while the degree of contamination indicated a moderate polymetallic contamination for rare earth elements and significant contamination for precious elements.

Rare earth elements (REEs): effects on germination and growth of selected crop and native plant species.

PubMed

Thomas, Philippe J; Carpenter, David; Boutin, Céline; Allison, Jane E

2014-02-01

The phytotoxicity of rare earth elements (REEs) is still poorly understood. The exposure-response relationships of three native Canadian plant species (common milkweed, Asclepias syriaca L., showy ticktrefoil, Desmodium canadense (L.) DC. and switchgrass, Panicum virgatum L.) and two commonly used crop species (radish, Raphanus sativus L., and tomato, Solanum lycopersicum L.) to the REEs lanthanum (La), yttrium (Y) and cerium (Ce) were tested. In separate experiments, seven to eight doses of each element were added to the soil prior to sowing seeds. Effects of REE dose on germination were established through measures of total percent germination and speed of germination; effects on growth were established through determination of above ground biomass. Ce was also tested at two pH levels and plant tissue analysis was conducted on pooled samples. Effects on germination were mostly observed with Ce at low pH. However, effects on growth were more pronounced, with detectable inhibition concentrations causing 10% and 25% reductions in biomass for the two native forb species (A. syriaca and D. canadense) with all REEs and on all species tested with Ce in both soil pH treatments. Concentration of Ce in aboveground biomass was lower than root Ce content, and followed the dose-response trend. From values measured in natural soils around the world, our results continue to support the notion that REEs are of limited toxicity and not considered extremely hazardous to the environment. However, in areas where REE contamination is likely, the slow accumulation of these elements in the environment could become problematic. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

RARE EARTH ELEMENTS IN FLY ASHES AS POTENTIAL INDICATORS OF ANTHROPOGENIC SOIL CONTAMINATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mattigod, Shas V.

2003-08-01

Studies of rare earth element (REE) content of disposed fly ashes and their potential mobility were neglected for decades because these elements were believed to be environmentally benign. A number of recent studies have now shown that REE may pose a long-term risk to the biosphere. Therefore, there is a critical need to study the REE concentrations in fly ash and their potential mobilization and dispersal upon disposal in the environment. We analyzed the REE content of bulk, size fractionated, and density separated fractions of three fly ash samples derived from combustion of sub bituminous coals from the western Unitedmore » States and found that the concentrations of these elements in bulk ashes were within the range typical of fly ashes derived from coals from the North American continent. The concentrations of light rare earth elements (LREE) such as La, Ce, and Nd, however, tended towards the higher end of the concentration range whereas, the concentrations of middle rare earth elements (MREE) (Sm and Eu) and heavy rare earth elements (HREE) (Lu) were closer to the lower end of the observed range for North American fly ashes. The concentrations of REE did not show any significant enrichment with decreasing particle size, this is typical of nonvolatile lithophilic element behavior during the combustion process. The lithophilic nature of REE was also confirmed by their concentrations in heavy density fractions of these fly ashes being on average about two times more enriched than the concentrations in the light density fractions. Shale normalized average of REE concentrations of fly ashes and coals revealed significant positive anomalies for Eu and Dy. Because of these distinctive positive anomalies of Eu and Dy, we believe that fly ash contamination of soils can be fingerprinted and distinguished from other sources of anthropogenic REE inputs in to the environment.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alam, A; Khan, M; McCallum, RW

2013-01-28

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

Siderophile and chalcophile element abundances in oceanic basalts, Pb isotope evolution and growth of the earth's core

NASA Technical Reports Server (NTRS)

Newsom, H. E.; White, W. M.; Jochum, K. P.; Hofmann, A. W.

1986-01-01

The hypothesis that the mantle Pb isotope ratios reflect continued extraction of Pb into the earth's core over geologic time is evaluated by studying the depeletion of chalcophile and siderophile elements in the mantle. Oceanic basalt samples are analyzed in order to determine the Pb, Sr, and Nd isotropic compositions and the abundances of siderophile and chalcophile elements and incompatible lithophile elements. The data reveal that there is no systematic variation of siderophile or chalcophile element abundances relative to abundances of lithophile elements and the Pb/Ce ratio of the mantle is constant. It is suggested that the crust formation involves nonmagmatic and magmatic processes.

Revisit of rare earth element fractionation during chemical weathering and river sediment transport

NASA Astrophysics Data System (ADS)

Su, Ni; Yang, Shouye; Guo, Yulong; Yue, Wei; Wang, Xiaodan; Yin, Ping; Huang, Xiangtong

2017-03-01

Although rare earth element (REE) has been widely applied for provenance study and paleoenvironmental reconstruction, its mobility and fractionation during earth surface processes from weathering to sediment deposition remain more clarification. We investigated the REE fractionations during chemical weathering and river sediment transport based on the systematic observations from a granodiorite-weathering profile and Mulanxi River sediments in southeast China. Two chemical phases (leachates and residues) were separated by 1 N HCl leaching and the leachates account for 20-70% of the bulk REE concentration. REEs in the weathering profile have been mobilized and fractionated to different extents during chemical weathering and pedogenesis. Remarkable cerium anomalies (Ce/Ce* = 0.1-10.6) occur during weathering as a result of coprecipitation with Mn (hydro)oxides in the profile, while poor or no Ce anomalies in the river sediments were observed. This contrasting feature sheds new light on the indication of Ce anomaly for redox change. The hydraulic sorting-induced mineral redistribution can further homogenize the weathering and pedogenic alterations and thus weaken the REE fractionations in river sediments. The mineral assemblage is the ultimate control on REE composition, and the Mn-Fe (hydro)oxides and secondary phosphate minerals are the main hosts of acid-leachable REEs while the clay minerals could be important reservoirs for residual REEs. We thus suggest that the widely used REE proxies such as (LREE/HREE)UCC ratio in the residues is reliable for the indication of sediment provenance, while the ratio in the leachates can indicate the total weathering process to some extent.

Chemiluminescent Diagnostics of Free-Radical Processes in an Abiotic System and in Liver Cells in the Presence of Nanoparticles Based on Rare-Earth Elements nReVO4:Eu3+ (Re = Gd, Y, La) and CeO2

NASA Astrophysics Data System (ADS)

Averchenko, E. A.; Kavok, N. S.; Klochkov, V. K.; Malyukin, Yu. V.

2014-11-01

We have used luminol-dependent chemiluminescence with Fenton's reagent to study the effect of nanoparticles based on rare-earth elements of different sizes and shapes on free-radical processes in abiotic and biotic cell-free systems, and also in isolated cells in vitro. We have estimated the effects of rare-earth orthovanadate nanoparticles of spherical (GdYVO4:Eu3+, 1-2 nm), spindle-shaped (GdVO4:Eu3+, 25 ×8 nm), and rod-shaped (LaVO4:Eu3+, 57 × (6-8) nm) nanoparticles and spherical CeO2 nanoparticles (sizes 1-2 nm and 8-10 nm). We have shown that in contrast to the abiotic system, in which all types of nanoparticles exhibit antiradical activity, in the presence of biological material, extra-small spherical (1-2 nm) nanoparticles of both types exhibit pro-oxidant activity, and also enhance pro-oxidant induced oxidative stress (for the pro-oxidants hydrogen peroxide and tert-butyl hydroperoxide). The effect of rare-earth orthovanadate spindle and rod shaped nanoparticles in this system was neutral; a moderate antioxidant effect was exhibited by 8-10 nm CeO2 nanoparticles.

Site-preference and valency for rare-earth sites in (R-Ce)2Fe14B [R =La,Nd] magnets

NASA Astrophysics Data System (ADS)

Alam, Aftab; Khan, Mahmud; McCallum, R. W.; Johnson, D. D.

2013-03-01

Rare-earth (R) permanent magnets of R2Fe14B have technological importance due to their high energy products, and they have two symmetry distinct R-sites (Wyckoff 4f and 4g) that affect chemistry and valence. Designing magnetic behavior and stability via alloying is technologically relevant to reduce critical (expensive) R-content while retaining key properties; cerium, an abundant (cheap) R-element, offers this potential. We calculate magnetic properties and Ce site preference in (R1-xCex)Fe14B [R=La,Nd] using density functional theory (DFT) methods. The Fe moments compare well with neutron scattering data - remain weakly affected by Hubbard U, but improved with spin-orbit coupling. In (La,Ce)2Fe14B, Ce alloys for 0 < x < 1 with a preference for smaller R(4f) sites, as observed, a trend we find unaffected by valence. Whereas in (Nd,Ce)2Fe14B, Ce is predicted to have limited alloying (x < 0.3) with a preference for larger R(4g) sites, resulting in weak partial ordering and segregation. Curie temperatures versus x were predicted for a typical sample processing and verified experimentally. We shall also present some initial results on the critical mixed valency of Ce in related compounds. Work at Ames Laboratory was supported by the U.S. Department of Energy, ARPA-E under the REACT program (0472-1526)

Mobility of rare earth element in hydrothermal process and weathering product: a review

NASA Astrophysics Data System (ADS)

Lintjewas, L.; Setiawan, I.

2018-02-01

The Rare Earth Element (REE), consists of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Lu, Ho, Er, Tm, Yb, are important elements to be used as raw materials of advanced technology such as semiconductors, magnets, and lasers. The research of REE in Indonesia has not been done. Several researches were conducted on granitic rocks and weathering product such as Bangka, Sibolga, West Kalimantan, West Sulawesi and Papua. REE can be formed by hydrothermal processes such as Bayan Obo, South China. The REE study on active hydrothermal system (geothermal) in this case also has the potential to produce mineral deposits. The purpose of this review paper is to know the mobility of REE on hydrothermal process and weathering products. Mobility of REE in the hydrothermal process can change the distribution patterns and REE content such as Ce, Eu, La, Lu, Nd, Sm, and Y. Another process besides the hydrothermal is weathering process. REE mobility is influenced by weathering products, where the REE will experience residual and secondary enrichment processes in heavier minerals.

Loparite-(Ce) from the Khibiny Alkaline Pluton, Kola Peninsula, Russia

NASA Astrophysics Data System (ADS)

Konopleva, N. G.; Ivanyuk, G. Yu.; Pakhomovsky, Ya. A.; Yakovenchuk, V. N.; Mikhailova, Yu. A.

2017-12-01

Data on the occurrence, morphology, anatomy, composition, and formation conditions of loparite-(Ce) in the Khibiny alkaline pluton are given. Loparite-(Ce), (Na,Ce,Sr)(Ce,Th)(Ti,Nb)2O6, resulted from metasomatic alteration and assimilation of metamorphic host rocks at the contact with foyaite as well as foyaite on the contact with foidolite. This alteration was the highest in pegmatite, and albitite developed there. A decrease in temperature resulted in enrichment of the perovskite and tausonite endmembers in loparite-(Ce) owing to a decrease in the loparite and lueshite endmembers. La and Ce sharply predominate among rare earth elements in the composition of loparite-(Ce).

Alkali element constraints on Earth-Moon relations

NASA Technical Reports Server (NTRS)

Norman, M. D.; Drake, M. J.; Jones, J. H.

1994-01-01

Given their range of volatilities, alkali elements are potential tracers of temperature-dependent processes during planetary accretion and formation of the Earth-Moon system. Under the giant impact hypothesis, no direct connection between the composition of the Moon and the Earth is required, and proto-lunar material does not necessarily experience high temperatures. Models calling for multiple collisions with smaller planetesimals derive proto-lunar materials mainly from the Earth's mantle and explicitly invoke vaporization, shock melting and volatility-related fractionation. Na/K, K/Rb, and Rb/Cs should all increase in response to thermal volatization, so theories which derive the Moon substantially from Earth's mantle predict these ratios will be higher in the Moon than in the primitive mantle of the Earth. Despite the overall depletion of volatile elements in the Moon, its Na/K and K/Rb are equal to or less than those of Earth. A new model presented here for the composition of Earth's continental crust, a major repository of the alkali elements, suggests the Rb/Cs of the Moon is also less than that of Earth. Fractionation of the alkali elements between Earth and Moon are in the opposite sense to predictions based on the relative volatilities of these elements, if the Moon formed by high-T processing of Earth's mantle. Earth, rather than the Moon, appears to carry a signature of volatility-related fractionation in the alkali elements. This may reflect an early episode of intense heating on Earth with the Moon's alkali budget accreting from cooler material.

Continental shelves as potential resource of rare earth elements.

PubMed

Pourret, Olivier; Tuduri, Johann

2017-07-19

The results of this study allow the reassessment of the rare earth elements (REE) external cycle. Indeed, the river input to the oceans has relatively flat REE patterns without cerium (Ce) anomalies, whereas oceanic REE patterns exhibit strong negative Ce anomalies and heavy REE enrichment. Indeed, the processes at the origin of seawater REE patterns are commonly thought to occur within the ocean masses themselves. However, the results from the present study illustrate that seawater-like REE patterns already occur in the truly dissolved pool of river input. This leads us to favor a partial or complete removal of the colloidal REE pool during estuarine mixing by coagulation, as previously shown for dissolved humic acids and iron. In this latter case, REE fractionation occurs because colloidal and truly dissolved pools have different REE patterns. Thus, the REE patterns of seawater could be the combination of both intra-oceanic and riverine processes. In this study, we show that the Atlantic continental shelves could be considered potential REE traps, suggesting further that shelf sediments could potentially become a resource for REE, similar to metalliferous deep sea sediments.

Rare earth elements in Japan Sea sediments and diagenetic behavior of Ce/Ce∗: results from ODP Leg 127

USGS Publications Warehouse

Murray, R.; Buchholtz ten Brink, Marilyn R.; Brumsack, Hans-Juergen; Gerlach, David C.; Russ III, G. Price

1991-01-01

Ce/Ce* profiles at all three sites increase monotonically with depth, and record progressive diagenetic LREE fractionation. The observed Ce/Ce* record does not respond to changes in oxygenation state of the overlying water, and Ce/Ce* correlated slightly better with depth than with age. The downhole increase in Ce/Ce* at Site 794 and Site 797 is a passive response to diagenetic transfer of LREE (except Ce) from sediment to interstitial water. At Site 795, the overall lack of correlation between Ce/Ce* and L(ln/Ybnsuggests that other processes are occurring which mask the diagenetic behavior of all LREEs. First-order calculations of the Ce budget in Japan Sea waters and sediment indicate that ~20% of the excess Ce adsorbed by settling particles is recycled within the water column, and that an additional ~38% is recycled at or near the seafloor (data from Masuzawa and Koyama, 1989). Thus, because the remaining excess Ce is only ~10% of the total Ce, there is not a large source of Ce to the deeply buried sediment, further suggesting that the downhole increase in Ce/Ce* is a passive response to diagenetic behavior of the other LREEs. The REE chemistry of Japan Sea sediment therefore predicts successive downhole addition of LREEs to deeply-buried interstitial waters.

Geochemistry of the rare earth elements in ferromanganese nodules from DOMES Site A, northern equatorial Pacific

USGS Publications Warehouse

Calvert, S.E.; Piper, D.Z.; Baedecker, P.A.

1987-01-01

The distribution of rare earth elements (REE) in ferromanganese nodules from DOMES Site A has been determined by instrumental neutron activation methods. The concentrations of the REE vary markedly. Low concentrations characterize samples from a depression (the valley), in which Quaternary sediments are thin or absent; high concentrations are found in samples from the surrounding abyssal hills (the highlands) where the Quaternary sediment section is relatively thick. Moreover, the valley nodules are strongly depleted in the light trivalent REE (LREE) and Ce compared with nodules from the highlands, some of the former showing negative Ce anomalies. The REE abundances in the nodules are strongly influenced by the REE abundances in coexisting bottom water. Some controls on the REE chemistry of bottom waters include: a) the more effective removal of the LREE relative to the HREE from seawater because of the greater degree of complexation of the latter elements with seawater ligands, b) the very efficient oxidative scavenging of Ce on particle surfaces in seawater, and c) the strong depletion of both Ce and the LREE in, or a larger benthic flux of the HREE into, the Antarctic Bottom Water (AABW) which flows through the valley. The distinctive REE chemistry of valley nodules is a function of their growth from geochemically evolved AABW. In contrast, the REE chemistry of highland nodules indicates growth from a local, less evolved seawater source. ?? 1987.

Rare Earth Elements | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

- Mineral Resources main content Rare Earth Elements Rare earth elements and the supply and demand of these deposits containing rare earth elements to meet the perceived future demand. High prices for rare earth earth element occurrences in the DGGS publications catalog. Department of Natural Resources, Division of

Rare earth element geochemistry of oceanic ferromanganese nodules and associated sediments

NASA Astrophysics Data System (ADS)

Elderfield, H.; Hawkesworth, C. J.; Greaves, M. J.; Calvert, S. E.

1981-04-01

Analyses have been made of REE contents of a well-characterized suite of deep-sea (> 4000 m.) principally todorokite-bearing ferromanganese nodules and associated sediments from the Pacific Ocean. REE in nodules and their sediments are closely related: nodules with the largest positive Ce anomalies are found on sediments with the smallest negative Ce anomalies; in contrast, nodules with the highest contents of other rare earths (3 + REE) are found on sediments with the lowest 3 + REE contents and vice versa. 143Nd /144Nd ratios in the nodules (˜0.51244) point to an original seawater source but an identical ratio for sediments in combination with the REE patterns suggests that diagenetic reactions may transfer elements into the nodules. Analysis of biogenic phases shows that the direct contribution of plankton and carbonate and siliceous skeletal materials to REE contents of nodules and sediments is negligible. Inter-element relationships and leaching tests suggest that REE contents are controlled by a P-rich phase with a REE pattern similar to that for biogenous apatite and an Fe-rich phase with a pattern the mirror image of that for sea water. It is proposed that 3 + REE concentrations are controlled by the surface chemistry of these phases during diagenetic reactions which vary with sediment accumulation rate. Processes which favour the enrichment of transition metals in equatorial Pacific nodules favour the depletion of 3 + REE in nodules and enrichment of 3 + REE in associated sediments. In contrast, Ce appears to be added both to nodules and sediments directly from seawater and is not involved in diagenetic reactions.

Systematic variation of rare earths in monazite

USGS Publications Warehouse

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

1953-01-01

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

Measurement of Rare Earth and Uranium Elements Using Laser-Induced Breakdown Spectroscopy (LIBS) in an Aerosol System for Nuclear Safeguards Applications

NASA Astrophysics Data System (ADS)

Williams, Ammon Ned

The primary objective of this research is to develop an applied technology and provide an assessment for remotely measuring and analyzing the real time or near real time concentrations of used nuclear fuel (UNF) elements in electroreners (ER). Here, Laser-Induced Breakdown Spectroscopy (LIBS) in UNF pyroprocessing facilities was investigated. LIBS is an elemental analysis method, which is based on the emission from plasma generated by focusing a laser beam into the medium. This technology has been reported to be applicable in solids, liquids (includes molten metals), and gases for detecting elements of special nuclear materials. The advantages of applying the technology for pyroprocessing facilities are: (i) Rapid real-time elemental analysis; (ii) Direct detection of elements and impurities in the system with low limits of detection (LOD); and (iii) Little to no sample preparation is required. One important challenge to overcome is achieving reproducible spectral data over time while being able to accurately quantify fission products, rare earth elements, and actinides in the molten salt. Another important challenge is related to the accessibility of molten salt, which is heated in a heavily insulated, remotely operated furnace in a high radiation environment within an argon gas atmosphere. This dissertation aims to address these challenges and approaches in the following phases with their highlighted outcomes: 1. Aerosol-LIBS system design and aqueous testing: An aerosol-LIBS system was designed around a Collison nebulizer and tested using deionized water with Ce, Gd, and Nd concentrations from 100 ppm to 10,000 ppm. The average %RSD values between the sample repetitions were 4.4% and 3.8% for the Ce and Gd lines, respectively. The univariate calibration curve for Ce using the peak intensities of the Ce 418.660 nm line was recommended and had an R 2 value, LOD, and RMSECV of 0.994, 189 ppm, and 390 ppm, respectively. The recommended Gd calibration curve was

Rare earth elements in parasol mushroom Macrolepiota procera.

PubMed

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

2017-04-15

This study aimed to investigate occurrence and distribution of 16 rare earth elements (REEs) in edible saprobic mushroom Macrolepiota procera, and to estimate possible intake and risk to human consumer. Mushrooms samples were collected from sixteen geographically diverse sites in the northern regions of Poland. The results showed that for Ce as the most abundant among the RREs in edible caps, the mean concentration was at 0.18±0.29mgkg -1 dry biomass. The mean concentration for Σ16 REEs determined in caps of fungus was 0.50mgkg -1 dry biomass and in whole fruiting bodies was 0.75mgkg -1 dry biomass. From a point of view by consumer, the amounts of REEs contained in edible caps of M. procera could be considered small. Hence, eating a tasty caps of this fungus would not result in a health risk for consumer because of exposure to the REEs. Copyright © 2016 Elsevier Ltd. All rights reserved.

Geochemical fractions of rare earth elements in soil around a mine tailing in Baotou, China

PubMed Central

Wang, Lingqing; Liang, Tao

2015-01-01

Rare earth mine tailing dumps are environmental hazards because tailing easily leaches and erodes by water and wind. To assess the influence of mine tailing on the geochemical behavior of rare earth elements (REEs) in soil, sixty-seven surface soil samples and three soil profile samples were collected from different locations near China’s largest rare earth mine tailing. The total concentration of REEs in surface soils ranged from 156 to 5.65 × 104 mg·kg−1 with an average value of 4.67 × 103 mg·kg−1, which was significantly higher than the average value in China (181 mg·kg−1). We found obvious fractionation of both light and heavy REEs, which was supported by the North American Shale Composite (NASC) and the Post-Archean Average Australian Shale (PAAS) normalized concentration ratios calculated for selected elements (LaN/YbN, LaN/SmN and GdN/YbN). A slightly positive Ce anomaly and a negative Eu anomaly were also found. For all 14 REEs in soils, enrichment was intensified by the mine tailing sources and influenced by the prevailing wind. PMID:26198417

Geochemical fractions of rare earth elements in soil around a mine tailing in Baotou, China.

PubMed

Wang, Lingqing; Liang, Tao

2015-07-22

Rare earth mine tailing dumps are environmental hazards because tailing easily leaches and erodes by water and wind. To assess the influence of mine tailing on the geochemical behavior of rare earth elements (REEs) in soil, sixty-seven surface soil samples and three soil profile samples were collected from different locations near China's largest rare earth mine tailing. The total concentration of REEs in surface soils ranged from 156 to 5.65 × 10(4) mg·kg(-1) with an average value of 4.67 × 10(3) mg·kg(-1), which was significantly higher than the average value in China (181 mg·kg(-1)). We found obvious fractionation of both light and heavy REEs, which was supported by the North American Shale Composite (NASC) and the Post-Archean Average Australian Shale (PAAS) normalized concentration ratios calculated for selected elements (La(N)/Yb(N), La(N)/Sm(N) and Gd(N)/Yb(N)). A slightly positive Ce anomaly and a negative Eu anomaly were also found. For all 14 REEs in soils, enrichment was intensified by the mine tailing sources and influenced by the prevailing wind.

The Ce-Ni-Si system as a representative of the rare earth-Ni-Si family: Isothermal section and new rare-earth nickel silicides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morozkin, A.V., E-mail: morozkin@tech.chem.msu.ru; Knotko, A.V.; Garshev, A.V.

CeSi{sub 2}; while no appreciable solubility was observed for the other binary compounds of the Ce-Ni-Si system. As a prolongation of Rare Earth-Ni-Si system’s isostructural rows, LaNi{sub 7}Si{sub 6} and YNi{sub 6.6}Si{sub 6.1} (GdNi{sub 7}Si{sub 6}-type), ScNi{sub 6}Si{sub 6} (YCo{sub 6}Ge{sub 6}-type), NdNi{sub 6}Si{sub 6} (YNi{sub 6}Si{sub 6}-type), (Tb, Ho){sub 2}Ni{sub 15}Si{sub 2} (Th{sub 2}Zn{sub 17}-type), Nd{sub 2}Ni{sub 2.3}Si{sub 0.7} and Sm{sub 2}Ni{sub 2.2}Si{sub 0.8} (Mo{sub 2}NiB{sub 2}-type), Nd{sub 3}Ni{sub 2.55}Si{sub 1.45} (W{sub 3}CoB{sub 3}-type) and (Tb, Dy){sub 7}Ni{sub 50}Si{sub 19} (Y{sub 7}Ni{sub 49}Si{sub 20}-type) compounds were synthesized and investigated. Magnetic properties of the CeNi{sub 6}Si{sub 6}, CeNi{sub 7}Si{sub 6}, CeNi{sub 8.8}Si{sub 4.2}, Ce{sub 6}Ni{sub 7}Si{sub 4}, CeNi{sub 5}Si, Ce{sub 2}Ni{sub 2.5}Si{sub 0.5}, Nd{sub 2}Ni{sub 2.3}Si{sub 0.7} and Dy{sub 7}Ni{sub 50}Si{sub 19} compounds have also been investigated and are presented here. - Highlights: • Ce-Ni-Si isothermal section was obtained at 870/1070 K. • Twenty one known ternary cerium nickel silicides were confirmed in Ce-Ni-Si. • Five new cerium nickel silicides were detected in Ce-Ni-Si. • Eleven new rare earth nickel silicides were detected in R-Ni-Si. • Magnetic properties of eight rare earth nickel silicides were investigated.« less

Effect of CeO2 on TiC Morphology in Ni-Based Composite Coating

NASA Astrophysics Data System (ADS)

Cai, Yangchuan; Luo, Zhen; Chen, Yao

2018-03-01

The TiC/Ni composite coating with different content of CeO2 was fabricated on the Cr12MoV steel by laser cladding. The microstructure of cladding layers with the different content of CeO2 from the bottom to the surface is columnar crystal, cellular crystal, and equiaxed crystal. When the content of CeO2 is 0 %, the cladding layer has a coarse and nonuniform microstructure and TiC particles gathering in the cladding layer, and then the wear resistance was reduced. Appropriate rare-earth elements refined and homogenised the microstructure and enhanced the content of carbides, precipitated TiC particles and original TiC particles were spheroidised and refined, the wear resistance of the cladding layer was improved significantly. Excessive rare-earth elements polluted the grain boundaries and made the excessive burning loss of TiC particles that reduced the wear resistance of the cladding layer.

A survey of 16 rare Earth elements in the major foods in China.

PubMed

Jiang, Ding Guo; Yang, Jie; Zhang, Shuo; Yang, Da Jin

2012-06-01

The aim of this survey was to investigate the level of contamination of the most consumed foods in China with 16 rare earth elements (REEs), and to provide the basic data for establishing and revising food safety standards for REEs. Sixteen REEs in foods were measured by inductively coupled plasma-mass spectrometry (ICP-MS) in the labs of the Centers for Disease Control and Prevention of four provinces and two municipalities, during 2009-2010. 1 231 samples were analyzed and 19 121 concentration data of 16 REEs were collected. The REEs levels in the investigated foods varied significantly. The concentrations of cerium (Ce), dysprosium (Dy), yttrium (Y), lanthanum (La), and neodymium (Nd) were relatively high, while the remaining eleven REEs were at low levels. The mean values of total rare earth element oxides (REOs) in cereals, fresh vegetables, fresh aquatic products, fresh meats and eggs varied from 0.052 mg/kg to 0.337 mg/kg. 16 REEs in the major foods were at very low contamination levels in the investigated regions. Copyright © 2012 The Editorial Board of Biomedical and Environmental Sciences. Published by Elsevier B.V. All rights reserved.

Distribution and Geochemistry of Rare-Earth Elements in Rivers of Southern and Eastern Primorye (Far East of Russia)

NASA Astrophysics Data System (ADS)

Chudaev, O. V.; Bragin, I. V.; A, Kharitonova N.; Chelnokov, G. A.

2016-03-01

The distribution and geochemistry of rare earth elements (REE) in anthropogenic, technogenic and natural surface waters of southern and eastern Primorye, Far East of Russia, are presented in this study. The obtained results indicated that most of REE (up to 70%) were transported as suspended matter, ratio between dissolved and suspended forms varing from the source to the mouth of rivers. It is shown that all REE (except Ce) in the source of the rivers are predominantly presented in dissolved form, however, the content of light and heavy REE is different. Short-term enrichment of light rare earth elements (LREE) caused by REE-rich runoff from waste dumps and mining is neutralized by the increase in river flow rate. Rivers in urban areas are characterized by high content of LREE in dissolved form and very low in suspended one.

Rare earth elements in intertidal sediments of Bohai Bay, China: concentration, fractionation and the influence of sediment texture.

PubMed

Zhang, Yong; Gao, Xuelu; Arthur Chen, Chen-Tung

2014-07-01

Surface sediments from intertidal Bohai Bay were assessed using a four-step sequential extraction procedure to determine their concentrations of rare earth elements (REEs) and the chemical forms in which those elements were present. The normalized ratios La/Gd and La/Yb showed that LREE contents were not significantly higher than the middle REEs or HREE contents. A negative Ce anomaly and positive Eu were observed in sand and silty sand sediments, whereas no significant Ce or Eu anomaly was found in clayey silt sediments. Residual fraction of REEs accounted for the majority of their total concentrations. Middle REEs were more easily leached than other REEs, especially in clayey silt sediment. REEs contents in the surface sediment from the intertidal Bohai Sea were consistent with data from the upper continental crust and China shallow sea sediments, indicating that they were generally unaffected by heavily anthropogenic effects from adjacent areas. Copyright © 2014 Elsevier Inc. All rights reserved.

[Effects of arbuscular mycorrhizal fungi on the growth and rare earth elements uptake of soybean grown in rare earth mine tailings].

PubMed

Guo, Wei; Zhao, Ren-xin; Zhao, Wen-jing; Fu, Rui-ying; Guo, Jiang-yuan; Zhang, Jun

2013-05-01

A greenhouse pot experiment was conducted to investigate the influence of arbuscular mycorrhizal (AM) fungi Glomus versiforme on the plant growth, nutrient uptake, C: N: P stoichiometric, uptake of heavy metals and rare earth elements by soybean (Glycine max) grown in rare earth mine tailings. The aim was to provide a basis for the revegetation of rare earth mine tailings. The results indicated that soybean had a high mycorrhizal colonization and symbiotic associations were successfully established with G. versiforme, with an average rate of approximately 67%. The colonization of G. versiforme significantly promoted the growth of soybean, increased P, K contents, and decreased C: N: P ratios, supporting the growth rate hypothesis. Inoculation with G. versiforme significantly decreased shoots and roots La, Ce, Pr and Nd concentrations of soybean compared to the control treatment. However, inoculation with G. versiforme had no significant effect on the heavy metal concentrations, except for significantly decreased shoot Fe and Cr concentrations and increased root Cd concentrations. The experiment demonstrates that AM fungi have a potential role for soybean to adapt the composite adversity of rare earth tailings and play a positive role in revegetation of rare earth mine tailings. Further studies on the role of AM fungi under natural conditions should be conducted.

Emission properties of Ce-doped alkaline earth borate glasses for scintillator applications

NASA Astrophysics Data System (ADS)

Torimoto, Aya; Masai, Hirokazu; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

2017-11-01

We investigate the photoluminescence (PL) and X-ray-induced luminescence properties of 0.1 mol% Ce-doped MO-B2O3 (M = Ca, Sr, and Ba) glasses. We also determine the Ce3+/(Ce3++Ce4+) ratio by X-ray absorption near-edge structure analyses. The emission intensities of PL, X-ray scintillation, and thermally stimulated luminescence (TSL) depend on the host glass composition. The order of the PL intensity from highest to lowest is as follows: Ca-substituted glass, Ba-substituted glass, and Sr-substituted glass. Our results suggest that the optical absorption edge and quantum yield (QY) are influenced by the local coordination state of Ce3+, which, in turn, is likely to be affected by the optical basicity. The order of the X-ray scintillation intensity from highest to lowest is reverse of that of the PL intensity. This is probably because the interaction probability of X-rays with matter depends on the effective atomic number of the material and the effective atomic number has a stronger influence on the scintillation intensity than does the QY. Though the TSL glow curves reveal that the density and energy depth of the trap sites depend on the substituted alkaline earth oxides, we are unable to correlate the electron spin resonance (ESR) spectra with the TSL results. Therefore, it is considered that the ESR active sites are not responsible for the TSL in these systems.

Rare Earth Element Mines, Deposits, and Occurrences

USGS Publications Warehouse

Orris, Greta J.; Grauch, Richard I.

2002-01-01

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

Core-Mantle Partitioning of Volatile Elements and the Origin of Volatile Elements in Earth and Moon

NASA Technical Reports Server (NTRS)

Righter, K.; Pando, K.; Danielson, L.; Nickodem, K.

2014-01-01

Depletions of siderophile elements in mantles have placed constraints on the conditions on core segregation and differentiation in bodies such as Earth, Earth's Moon, Mars, and asteroid 4 Vesta. Among the siderophile elements there are a sub-set that are also volatile (volatile siderophile elements or VSE; Ga, Ge, In, As, Sb, Sn, Bi, Zn, Cu, Cd), and thus can help to constrain the origin of volatile elements in these bodies, and in particular the Earth and Moon. One of the fundamental observations of the geochemistry of the Moon is the overall depletion of volatile elements relative to the Earth, but a satisfactory explanation has remained elusive. Hypotheses for Earth include addition during accretion and core formation and mobilized into the metallic core, multiple stage origin, or addition after the core formed. Any explanation for volatile elements in the Earth's mantle must also be linked to an explanation of these elements in the lunar mantle. New metal-silicate partitioning data will be applied to the origin of volatile elements in both the Earth and Moon, and will evaluate theories for exogenous versus endogenous origin of volatile elements.

RRh2Al10 (R = Ce, Yb): New intermetallic compounds in the 1 : 2 : 10 stoichiometry series

NASA Astrophysics Data System (ADS)

Strydom, A. M.; Djoumessi, R. F.; Blinova, M.; Tursina, A.; Nesterenko, S.; Avzuragova, V.

2018-05-01

The orthorhombic, space group Cmcm YbFe2Al10 structure type series of compounds are known to form with practically the entire series of rare-earth elements R, but only with the three d - electron elements Fe, Ru, and Os. The Ce-derivatives in particular have been of much interest since the first reports of their highly unusual physical properties. Classified as Kondo insulators, CeRu2Al10 and CeOs2Al10 controversially order magnetically and with uncharacteristically high Néel temperatures of ≃ 28 K. CeFe2Al10 on the other hand shows pronounced semiconducting and Kondo features but remains paramagnetic. As part of our ongoing studies into the rich physics of this class of materials we have succeeded in synthesizing new members of the 1:2:10 stoichiometry involving the chemical element Rh for the first time. CeRh2Al10 is found to crystallize in the tetragonal system with space group I41 / amd . Yb Rh2Al10 on the other hand forms in the serial Cmcm orthorhombic structure type. We discuss important similarities between the two types. At 5.310 Å the shortest Ce-Ce distance is, likewise to the situation in CeRu2Al10 and CeOs2Al10 , also well above the Hill limit of 3.40 Å. Despite the cage-like structure and large rare-earth separation distances, this study reveals the onset of long-range magnetic ordering in CeRh2Al10 at 3.9 K. The magnetic ordering develops out of an incoherent Kondo state that dominates the electrical resistivity below about 40 K.

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

NASA Astrophysics Data System (ADS)

Stosch, Heinz-Günter

2016-08-01

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andrew Fowler

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

Contributions of Rare Earth Element (La,Ce) Addition to the Impact Toughness of Low Carbon Cast Niobium Microalloyed Steels

NASA Astrophysics Data System (ADS)

Torkamani, Hadi; Raygan, Shahram; Garcia Mateo, Carlos; Rassizadehghani, Jafar; Palizdar, Yahya; San-Martin, David

2018-03-01

In this research Rare Earth elements (RE), La and Ce (200 ppm), were added to a low carbon cast microalloyed steel to disclose their influence on the microstructure and impact toughness. It is suggested that RE are able to change the interaction between the inclusions and matrix during the solidification process (comprising peritectic transformation), which could affect the microstructural features and consequently the impact property; compared to the base steel a clear evolution was observed in nature and morphology of the inclusions present in the RE-added steel i.e. (1) they changed from MnS-based to (RE,Al)(S,O) and RE(S)-based; (2) they obtained an aspect ratio closer to 1 with a lower area fraction as well as a smaller average size. Besides, the microstructural examination of the matrix phases showed that a bimodal type of ferrite grain size distribution exists in both base and RE-added steels, while the mean ferrite grain size was reduced from 12 to 7 μm and the bimodality was redressed in the RE-added steel. It was found that pearlite nodule size decreases from 9 to 6 μm in the RE-added steel; however, microalloying with RE caused only a slight decrease in pearlite volume fraction. After detailed fractography analyses, it was found that, compared to the based steel, the significant enhancement of the impact toughness in RE-added steel (from 63 to 100 J) can be mainly attributed to the differences observed in the nature of the inclusions, the ferrite grain size distribution, and the pearlite nodule size. The presence of carbides (cementite) at ferrite grain boundaries and probable change in distribution of Nb-nanoprecipitation (promoted by RE addition) can be considered as other reasons affecting the impact toughness of steels under investigation.

Contributions of Rare Earth Element (La,Ce) Addition to the Impact Toughness of Low Carbon Cast Niobium Microalloyed Steels

NASA Astrophysics Data System (ADS)

Torkamani, Hadi; Raygan, Shahram; Garcia Mateo, Carlos; Rassizadehghani, Jafar; Palizdar, Yahya; San-Martin, David

2018-07-01

In this research Rare Earth elements (RE), La and Ce (200 ppm), were added to a low carbon cast microalloyed steel to disclose their influence on the microstructure and impact toughness. It is suggested that RE are able to change the interaction between the inclusions and matrix during the solidification process (comprising peritectic transformation), which could affect the microstructural features and consequently the impact property; compared to the base steel a clear evolution was observed in nature and morphology of the inclusions present in the RE-added steel i.e. (1) they changed from MnS-based to (RE,Al)(S,O) and RE(S)-based; (2) they obtained an aspect ratio closer to 1 with a lower area fraction as well as a smaller average size. Besides, the microstructural examination of the matrix phases showed that a bimodal type of ferrite grain size distribution exists in both base and RE-added steels, while the mean ferrite grain size was reduced from 12 to 7 μm and the bimodality was redressed in the RE-added steel. It was found that pearlite nodule size decreases from 9 to 6 μm in the RE-added steel; however, microalloying with RE caused only a slight decrease in pearlite volume fraction. After detailed fractography analyses, it was found that, compared to the based steel, the significant enhancement of the impact toughness in RE-added steel (from 63 to 100 J) can be mainly attributed to the differences observed in the nature of the inclusions, the ferrite grain size distribution, and the pearlite nodule size. The presence of carbides (cementite) at ferrite grain boundaries and probable change in distribution of Nb-nanoprecipitation (promoted by RE addition) can be considered as other reasons affecting the impact toughness of steels under investigation.

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

USGS Publications Warehouse

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

1955-01-01

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

Distribution and Translocation of 141Ce (III) in Horseradish

PubMed Central

Guo, Xiaoshan; Zhou, Qing; Lu, Tianhong; Fang, Min; Huang, Xiaohua

2007-01-01

Background and Aims Rare earth elements (REEs) are used in agriculture and a large amount of them contaminate the environment and enter foods. The distribution and translocation of 141Ce (III) in horseradish was investigated in order to help understand the biochemical behaviour and toxic mechanism of REEs in plants. Method The distribution and translocation of 141Ce (III) in horseradish were investigated using autoradiography, liquid scintillation counting (LSC) and electron microscopic autoradiography (EMARG) techniques. The contents of 141Ce (III) and nutrient elements were analysed using an inductively coupled plasma-atomic emission spectrometer (ICP-AES). Results The results from autoradiography and LSC indicated that 141Ce (III) could be absorbed by horseradish and transferred from the leaf to the leaf-stalk and then to the root. The content of 141Ce (III) in different parts of horseradish was as follows: root > leaf-stalk > leaf. The uptake rates of 141Ce (III) in horseradish changed with the different organs and time. The content of 141Ce (III) in developing leaves was greater than that in mature leaves. The results from EMARG indicated that 141Ce (III) could penetrate through the cell membrane and enter the mesophyll cells, being present in both extra- and intra-cellular deposits. The contents of macronutrients in horseradish were decreased by 141Ce (III) treatment. Conclusions 141Ce (III) can be absorbed and transferred between organs of horseradish with time, and the distribution was found to be different at different growth stages. 141Ce (III) can enter the mesophyll cells via apoplast and symplast channels or via plasmodesmata. 141Ce (III) can disturb the metabolism of macronutrients in horseradish. PMID:17921527

MaRGEE: Move and Rotate Google Earth Elements

NASA Astrophysics Data System (ADS)

Dordevic, Mladen M.; Whitmeyer, Steven J.

2015-12-01

Google Earth is recognized as a highly effective visualization tool for geospatial information. However, there remain serious limitations that have hindered its acceptance as a tool for research and education in the geosciences. One significant limitation is the inability to translate or rotate geometrical elements on the Google Earth virtual globe. Here we present a new JavaScript web application to "Move and Rotate Google Earth Elements" (MaRGEE). MaRGEE includes tools to simplify, translate, and rotate elements, add intermediate steps to a transposition, and batch process multiple transpositions. The transposition algorithm uses spherical geometry calculations, such as the haversine formula, to accurately reposition groups of points, paths, and polygons on the Google Earth globe without distortion. Due to the imminent deprecation of the Google Earth API and browser plugin, MaRGEE uses a Google Maps interface to facilitate and illustrate the transpositions. However, the inherent spatial distortions that result from the Google Maps Web Mercator projection are not apparent once the transposed elements are saved as a KML file and opened in Google Earth. Potential applications of the MaRGEE toolkit include tectonic reconstructions, the movements of glaciers or thrust sheets, and time-based animations of other large- and small-scale geologic processes.

Major, minor, trace and rare earth elements in sediments of the Bijagós archipelago, Guinea-Bissau.

PubMed

Carvalho, Lina; Figueira, Paula; Monteiro, Rui; Reis, Ana Teresa; Almeida, Joana; Catry, Teresa; Lourenço, Pedro Miguel; Catry, Paulo; Barbosa, Castro; Catry, Inês; Pereira, Eduarda; Granadeiro, José Pedro; Vale, Carlos

2018-04-01

Sixty sediment samples from four sites in the Bijagós archipelago were characterized for fine fraction, loss on ignition, major, minor and trace elemental composition (Al, Fe, Ca, Mg, Ti, P, Zr, Mn, Cr, Sr, Ba, B, V, Li, Zn, Ni, Pb, As, Co, U, Cu, Cs and Cd), and the elements of the La-Lu series. Element concentrations were largely explained by the Al content and the proportion of fine fraction content, with the exception of Ca and Sr. Sediments showed enhanced Ti, U, Cr, As and Cd concentrations with respect to estimated upper crust values, most likely mirroring a regional signature. Rare earth elements were in deficit relatively to the North American Shale Composite (NASC), mainly in coarser material. No pronounced Ce-anomaly was observed, while Eu-anomalies were positive in most analyzed sediments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Post-depositional redistribution processes and their effects on middle rare earth element precipitation and the cerium anomaly in sediments in the South Korea Plateau, East Sea

NASA Astrophysics Data System (ADS)

Kang, Jeongwon; Jeong, Kap-Sik; Cho, Jin Hyung; Lee, Jun Ho; Jang, Seok; Kim, Seong Ryul

2014-03-01

We sampled two box-core sediments from the slope of the eastern South Korea Plateau (SKP) in the East Sea (Sea of Japan) at water depths of 1400 and 1700 m. Two chemical fractions of extractable (hydroxylamine/acetic acid) and residual rare earth elements (REEs) together with Al, Ca, Fe, Mg, Mn, P, S, As, Mo, and U were analyzed to assess the post-depositional redistribution of REEs. Extractable Fe and Mn are noticeably abundant in the oxic topmost sediment layer (<3 cm). However, some trace elements (e.g., S, As, Mo, U) are more abundant at depth, where redox conditions are different. Analysis of upper continental crust (UCC)-normalized (La/Gd)UCC, (La/Yb)UCC, and (Ce/Ce*)UCC revealed that the extractable REE is characterized by middle REE (MREE) enrichment and a positive cerium (Ce) anomaly, different from the case of the residual fraction which shows slight enrichment in light REEs (LREEs) with no Ce anomaly. The extractable MREEs seem to have been incorporated into high-Mg calcite during reductive dissolution of Fe oxyhydroxides. In the top sediment layer, the positive Ce anomaly is attributed to Ce oxide, which can be mobilized in deeper oxygen-poor environments and redistributed in the sediment column. In addition, differential concentrations of Ce and other LREEs in pore water appear to result in variable (Ce/Ce*)UCC ratios in the extractable fraction at depth.

NETL’s Rare Earth Elements Research

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

The National Energy Technology Laboratory has established a Rare Earth Elements (REE) program. REEs are a series of 17 chemical elements found in the Earth’s crust. They are an essential component to technology, health care, transportation and national defense.

The chemistry of rare earth elements in the solar nebula

NASA Technical Reports Server (NTRS)

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

1984-01-01

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

Ce Core-Level Spectroscopy, and Magnetic and Electrical Transport Properties of Lightly Ce-Doped YCoO3

NASA Astrophysics Data System (ADS)

Kobayashi, Yoshihiko; Koike, Tsuyoshi; Okawa, Mario; Takayanagi, Ryohei; Takei, Shohei; Minohara, Makoto; Kobayashi, Masaki; Horiba, Koji; Kumigashira, Hiroshi; Yasui, Akira; Ikenaga, Eiji; Saitoh, Tomohiko; Asai, Kichizo

2016-11-01

We have investigated the Ce and Co core level spectroscopy, and the magnetic and electrical transport properties of lightly Ce-doped YCoO3. We have successfully synthesized single-phase Y1-xCexCoO3 for 0.0 ≤ x ≤ 0.1 by the sol-gel method. Hard X-ray photoelectron and X-ray absorption spectroscopy experiments reveal that the introduced Ce ions are tetravalent, which is considered to be the first case of electron doping into bulk trivalent Co oxides with perovskite RECoO3 (RE: rare-earth element or Y) caused by RE site substitution. The magnitude of the effective magnetic moment peff obtained from the temperature dependence of magnetic susceptibility χ(T) at higher temperatures is close to that for high-spin Co2+ introduced by the Ce doping, implying that the electrons doped into the Co site induce Co2+ with a high-spin state. For x = 0.1, ferromagnetic ordering is observed below about 7 K. Electrical transport properties such as resistivity and thermoelectric power show that negative electron-like carriers are introduced by Ce substitution.

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

NASA Astrophysics Data System (ADS)

Kuk, Seoung Woo; Kim, Ki Hwan; Kim, Jong Hwan; Song, Hoon; Oh, Seok Jin; Park, Jeong-Yong; Lee, Chan Bock; Youn, Young-Sang; Kim, Jong-Yun

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.

Fractionation of rare-earth elements in allanite and monazite as related to geology of the Mt. Wheeler mine area, Nevada

USGS Publications Warehouse

Lee, D.E.; Bastron, H.

1967-01-01

Rare-earth contents of 20 allanites and 13 monazites, accessory minerals from a restricted outcrop area of intrusive granitic rocks, are reported. A quantity called sigma (??), which is the sum of the atomic percentages of La, Ce and Pr, is used as an index of composition with respect to the rare-earth elements. Values of sigma vary from 61.3 to 80.9 at.% for these allanites and monazites, representing an appreciable range of composition in terms of the rare-earth elements. Degree of fractionation of rare earths varies directly with CaO content of the granitic rocks, which in turn depends largely on proximity of limestone. Four xenoliths included in the study suggest that spotty mosaic equilibria are superimposed on the regional gradients and that locally the degree of fractionation of rare earths responds to whole rock composition over distances of a few yards or less. The chemistry of the granitic rocks under study appears to be similar in some respects to that of alkalio rocks and carbonatites. Allanites from the most calcium-rich rocks show a pronounced concentration of the most basic rare earths, and whole-rock concentrations of such rare constituents as total cerium earths, Zr, F, Ti, Ba and Sr increase sympathetically with whole-rock calcium. The explanation for the concentration gradients observed in this chemical system must involve assimilation more than magmatic differentiation. ?? 1967.

Photoeffect cross sections of several rare-earth elements for 323-keV photons

NASA Astrophysics Data System (ADS)

Umesh, T. K.; Anasuya, S. J.; Shylaja Kumari, J.; Gowda, Channe; Gopinathan Nair, K. P.; Gowda, Ramakrishna

1992-02-01

Total-attenuation cross sections of the oxides of rare-earth elements such as La, Ce, Pr, Nd, Sm, Gd, Dy, Ho, and Er, and also NaNO3 and NaNO2 have been measured in a narrow-beam geometry setup at 323 keV. The total-attenuation cross section for oxygen was obtained as the difference in NaNO3 and NaNO2 cross sections. Using this, the total-attenuation cross sections of the individual lanthanides have been obtained with the aid of the mixture rule. From these, the photoeffect cross sections were derived by subtracting the scattering contribution. These values are found to agree well with Scofield's theoretical data [University of California Report No. UCRL 51326, 1973 (unpublished)].

Impeding effect of Ce on He bubble growth in bcc Fe

NASA Astrophysics Data System (ADS)

Hao, W.; Geng, W. T.

2012-06-01

Our first-principles density functional theory calculations suggest that the rare earth element Ce has a strong attraction to He (-1.31 eV/atom pair) in bcc Fe, even stronger than He-He attraction (-1.18 eV). The segregated Ce layer at the He bubble surface could introduce an additional energy barrier (0.40 eV) to trespassing He atoms. Therefore, Ce could not only have a pinning effect on mobile He atoms and hence reduce merging rate of He clusters, but also serve as a cover layer to repel further He atoms and thus slows down the bubble growth. The low cost makes Ce a great advantage over Au, which was recently predicted to have similar effect.

Rare Earth Element Concentration of Wyoming Thermal Waters Update

DOE Office of Scientific and Technical Information (OSTI.GOV)

Quillinan, Scott; Nye, Charles; Neupane, Hari

Updated version of data generated from rare earth element investigation of produced waters. These data represent major, minor, trace, isotopes, and rare earth element concentrations in geologic formations and water associated with oil and gas production.

SEPARATION OF TRANSURANIC ELEMENTS FROM RARE EARTH COMPOUNDS

DOEpatents

Kohman, T.P.

1961-11-21

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

Interoceanic variation in the rare earth, major, and trace element depositional chemistry of chert: Perspectives gained from the DSDP and ODP record

USGS Publications Warehouse

Murray, R.W.; Buchholtz ten Brink, Marilyn R.; Gerlach, David C.; Russ III, G. Price; Jones, David L.

1992-01-01

Rare earth element (REE), major, and trace element abundances and relative fractionations in forty nodular cherts sampled by the Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) indicate that the REE composition of chert records the interplay between terrigenous sources and scavenging from the local seawater. Major and (non-REE) trace element ratios indicate that the aluminosilicate fraction within the chert is similar to NASC (North American Shale Composite), with average Pacific chert including ~7% NASC-like particles, Indian chert ~ 11% NASC, Atlantic chert ~ 17% NASC, and southern high latitude (SHL) chert 53% NASC. Using La as a proxy for ∑REE, approximations of Laex (the amount of La in excess of that supplied by the detrital aluminosilicate fraction) indicate that Pacific chert contains the greatest Laex (85% of Latotal) and SHL chert the least (38% of Latotal). As shown by interelement associations, this Laex is most likely an adsorbed component onto aluminosilicate and phosphatic phases.Accordingly, chert from the large Pacific Ocean, where deposition occurs relatively removed from significant terrigenous input, records a depositional REE signal dominated by adsorption of dissolved REEs from seawater. Pacific chert CeCe*⪡ 1 and LanYbn ~ 0.8-1, resulting from adsorption of local Ce-depleted seawater and preferential adsorption of LREEs from seawater (e.g., LanYbn ~ 0.4), which increases the LanYbn ratio recorded in chert. Chert from the Atlantic basin, a moderately sized ocean basin lined by passive margins and with more terrigenous input than the Pacific, records a mix of adsorptive and terrigenous REE signals, with moderately negative Ce anomalies and LanYbn">LanYbn ratios intermediate to those of the Pacific and those of terrigenous input. Chert from the SHL region is dominated by the large terrigenous input on the Antarctic passive margin, with inherited CeCe*~1">CeCe*~1 and inherited LanYbn">LanYbn values of ~1.2–1

Rare earth element scavenging in seawater

NASA Astrophysics Data System (ADS)

Byrne, Robert H.; Kim, Ki-Hyun

1990-10-01

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

Simultaneous determination of rare earth elements in ore and anti-corrosion coating samples using a portable capillary electrophoresis instrument with contactless conductivity detection.

PubMed

Nguyen, Thi Anh Huong; Nguyen, Van Ri; Le, Duc Dung; Nguyen, Thi Thanh Binh; Cao, Van Hoang; Nguyen, Thi Kim Dung; Sáiz, Jorge; Hauser, Peter C; Mai, Thanh Duc

2016-07-29

The employment of an in-house-made capillary electrophoresis (CE) instrument with capacitively coupled contactless conductivity detection (C(4)D) as a simple and inexpensive solution for simultaneous determination of many rare earth elements (REEs) in ore samples from Vietnam, as well as in anti-corrosion coating samples is reported. 14 REEs (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) were determined using an electrolyte composed of 20mM arginine and 10mM α-hydroxyisobutyric acid adjusted to pH 4.2 with acetic acid. The best detection limit achieved was 0.24mg/L using the developed CE-C(4)D method. Good agreement between results from CE-C(4)D and the confirmation method (ICP-MS) was achieved, with a coefficient of determination (r(2)) for the two pairs of data of 0.998. Copyright © 2016 Elsevier B.V. All rights reserved.

Light rare earth element depletion during Deepwater Horizon blowout methanotrophy.

PubMed

Shiller, A M; Chan, E W; Joung, D J; Redmond, M C; Kessler, J D

2017-09-04

Rare earth elements have generally not been thought to have a biological role. However, recent work has demonstrated that the light REEs (LREEs: La, Ce, Pr, and Nd) are essential for at least some methanotrophs, being co-factors in the XoxF type of methanol dehydrogenase (MDH). We show here that dissolved LREEs were significantly removed in a submerged plume of methane-rich water during the Deepwater Horizon (DWH) well blowout. Furthermore, incubation experiments conducted with naturally methane-enriched waters from hydrocarbon seeps in the vicinity of the DWH wellhead also showed LREE removal concurrent with methane consumption. Metagenomic sequencing of incubation samples revealed that LREE-containing MDHs were present. Our field and laboratory observations provide further insight into the biochemical pathways of methanotrophy during the DWH blowout. Additionally, our results are the first observations of direct biological alteration of REE distributions in oceanic systems. In view of the ubiquity of LREE-containing MDHs in oceanic systems, our results suggest that biological uptake of LREEs is an overlooked aspect of the oceanic geochemistry of this group of elements previously thought to be biologically inactive and an unresolved factor in the flux of methane, a potent greenhouse gas, from the ocean.

Bioleaching of rare earth elements from monazite sand.

PubMed

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

2016-02-01

Three fungal strains were found to be capable of bioleaching rare earth elements from monazite, a rare earth phosphate mineral, utilizing the monazite as a phosphate source and releasing rare earth cations into solution. These organisms include one known phosphate solubilizing fungus, Aspergillus niger ATCC 1015, as well as two newly isolated fungi: an Aspergillus terreus strain ML3-1 and a Paecilomyces spp. strain WE3-F. Although monazite also contains the radioactive element Thorium, bioleaching by these fungi preferentially solubilized rare earth elements over Thorium, leaving the Thorium in the solid residual. Adjustments in growth media composition improved bioleaching performance measured as rare earth release. Cell-free spent medium generated during growth of A. terreus strain ML3-1 and Paecilomyces spp. strain WE3-F in the presence of monazite leached rare earths to concentrations 1.7-3.8 times those of HCl solutions of comparable pH, indicating that compounds exogenously released by these organisms contribute substantially to leaching. Organic acids released by the organisms included acetic, citric, gluconic, itaconic, oxalic, and succinic acids. Abiotic leaching with laboratory prepared solutions of these acids was not as effective as bioleaching or leaching with cell-free spent medium at releasing rare earths from monazite, indicating that compounds other than the identified organic acids contribute to leaching performance. © 2015 Wiley Periodicals, Inc.

Siderophore-mediated oxidation of Ce and fractionation of HREE by Mn (hydr)oxide-coprecipitation and sorption on MnO2: Experimental evidence for negative Ce-anomalies in abiogenic manganese precipitates

NASA Astrophysics Data System (ADS)

Krämer, Dennis; Tepe, Nathalie; Bau, Michael

2014-05-01

)oxides (e.g., Tanaka et al., 2010, Loges et al., 2012). Our experimental results demonstrate that biogenic organic ligands such as hydroxamate siderophores, may produce solutions with positive Ce anomaly (Bau et al., 2013) and may even counteract the surface oxidation of Ce on Mn (hydr)oxides. References Bau, M., Tepe, N., Mohwinkel, D., 2013. Siderophore-promoted transfer of rare earth elements and iron from volcanic ash into glacial meltwater, river and ocean water. Earth Planet. Sci. Lett. 364, 30-36. Christenson E. A. and Schijf J. (2011) Stability of YREE complexes with the trihydroxamate siderophore desferrioxamine B at seawater ionic strength. Geochim. Cosmochim. Acta 75, 7047-7062. Loges, A., Wagner, T., Barth, M., Bau, M., Göb, S., and Markl, G. 2012. Negative Ce anomalies in Mn oxides: The role of Ce4+ mobility during water-mineral interaction. Geochimica and Cosmochimica Acta 86, 296-317 Ohta A. and Kawabe I. (2001) REE (III) adsorption onto Mn dioxide (delta-MnO2) and Fe oxyhydroxide: Ce(III) oxidation by delta-MnO2. Geochim. Cosmochim. Acta 65, 695-703. Tanaka K., Tani Y., Takahashi Y., Tanimizu M., Suzuki Y., Kozai N. and Ohnuki T. (2010) A specific Ce oxidation process during sorption of rare earth elements on biogenic Mn oxide produced by Acremonium sp. strain KR21-2. Geochim. Cosmochim. Acta 74, 5463-5477.

Membrane assisted solvent extraction for rare earth element recovery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhave, Ramesh R.; Kim, Daejin; Peterson, Eric S.

Systems and methods for the recovery of rare earth elements are provided. The systems and methods generally include membrane assisted solvent extraction using permeable hollow fibers having an immobilized organic phase within the pores of the hollow fibers. The permeable hollow fibers are generally in contact with an acidic aqueous feed on one side thereof and a strip solution on another side thereof. The systems and methods generally include the simultaneous extraction and stripping of rare earth elements as a continuous recovery process that is well suited for post-consumer products, end-of-life products, and other recovery sources of rare earth elements.

Thorium, uranium and rare earth elements content in lanthanide concentrate (LC) and water leach purification (WLP) residue of Lynas advanced materials plant (LAMP)

DOE Office of Scientific and Technical Information (OSTI.GOV)

AL-Areqi, Wadeeah M., E-mail: walareqi@yahoo.com; Majid, Amran Ab., E-mail: walareqi@yahoo.com; Sarmani, Sukiman, E-mail: walareqi@yahoo.com

Lynas Advanced Materials Plant (LAMP) has been licensed to produce the rare earths elements since early 2013 in Malaysia. LAMP processes lanthanide concentrate (LC) to extract rare earth elements and subsequently produce large volumes of water leach purification (WLP) residue containing naturally occurring radioactive material (NORM). This residue has been rising up the environmental issue because it was suspected to accumulate thorium with significant activity concentration and has been classified as radioactive residue. The aim of this study is to determine Th-232, U-238 and rare earth elements in lanthanide concentrate (LC) and water leach purification (WLP) residue collected from LAMPmore » and to evaluate the potential radiological impacts of the WLP residue on the environment. Instrumental Neutron Activation Analysis and γ-spectrometry were used for determination of Th, U and rare earth elements concentrations. The results of this study found that the concentration of Th in LC was 1289.7 ± 129 ppm (5274.9 ± 527.6Bq/kg) whereas the Th and U concentrations in WLP were determined to be 1952.9±17.6 ppm (7987.4 ± 71.9 Bq/kg) and 17.2 ± 2.4 ppm respectively. The concentrations of Th and U in LC and WLP samples determined by γ- spectrometry were 1156 ppm (4728 ± 22 Bq/kg) and 18.8 ppm and 1763.2 ppm (7211.4 Bq/kg) and 29.97 ppm respectively. This study showed that thorium concentrations were higher in WLP compare to LC. This study also indicate that WLP residue has high radioactivity of {sup 232}Th compared to Malaysian soil natural background (63 - 110 Bq/kg) and come under preview of Act 304 and regulations. In LC, the Ce and Nd concentrations determined by INAA were 13.2 ± 0.6% and 4.7 ± 0.1% respectively whereas the concentrations of La, Ce, Nd and Sm in WLP were 0.36 ± 0.04%, 1.6%, 0.22% and 0.06% respectively. This result showed that some amount of rare earth had not been extracted and remained in the WLP and may be considered to be reextracted.« less

Thorium, uranium and rare earth elements content in lanthanide concentrate (LC) and water leach purification (WLP) residue of Lynas advanced materials plant (LAMP)

NASA Astrophysics Data System (ADS)

AL-Areqi, Wadeeah M.; Majid, Amran Ab.; Sarmani, Sukiman

2014-02-01

Lynas Advanced Materials Plant (LAMP) has been licensed to produce the rare earths elements since early 2013 in Malaysia. LAMP processes lanthanide concentrate (LC) to extract rare earth elements and subsequently produce large volumes of water leach purification (WLP) residue containing naturally occurring radioactive material (NORM). This residue has been rising up the environmental issue because it was suspected to accumulate thorium with significant activity concentration and has been classified as radioactive residue. The aim of this study is to determine Th-232, U-238 and rare earth elements in lanthanide concentrate (LC) and water leach purification (WLP) residue collected from LAMP and to evaluate the potential radiological impacts of the WLP residue on the environment. Instrumental Neutron Activation Analysis and γ-spectrometry were used for determination of Th, U and rare earth elements concentrations. The results of this study found that the concentration of Th in LC was 1289.7 ± 129 ppm (5274.9 ± 527.6Bq/kg) whereas the Th and U concentrations in WLP were determined to be 1952.9±17.6 ppm (7987.4 ± 71.9 Bq/kg) and 17.2 ± 2.4 ppm respectively. The concentrations of Th and U in LC and WLP samples determined by γ- spectrometry were 1156 ppm (4728 ± 22 Bq/kg) & 18.8 ppm and 1763.2 ppm (7211.4 Bq/kg) &29.97 ppm respectively. This study showed that thorium concentrations were higher in WLP compare to LC. This study also indicate that WLP residue has high radioactivity of 232Th compared to Malaysian soil natural background (63 - 110 Bq/kg) and come under preview of Act 304 and regulations. In LC, the Ce and Nd concentrations determined by INAA were 13.2 ± 0.6% and 4.7 ± 0.1% respectively whereas the concentrations of La, Ce, Nd and Sm in WLP were 0.36 ± 0.04%, 1.6%, 0.22% and 0.06% respectively. This result showed that some amount of rare earth had not been extracted and remained in the WLP and may be considered to be reextracted.

How PNNL Extracts Rare Earth Elements from Geothermal Brine

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2016-07-12

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

Carbonatite and alkaline intrusion-related rare earth element deposits–A deposit model

USGS Publications Warehouse

Verplanck, Philip L.; Van Gosen, Bradley S.

2011-01-01

The rare earth elements are not as rare in nature as their name implies, but economic deposits with these elements are not common and few deposits have been large producers. In the past 25 years, demand for rare earth elements has increased dramatically because of their wide and diverse use in high-technology applications. Yet, presently the global production and supply of rare earth elements come from only a few sources. China produces more than 95 percent of the world's supply of rare earth elements. Because of China's decision to restrict exports of these elements, the price of rare earth elements has increased and industrial countries are concerned about supply shortages. As a result, understanding the distribution and origin of rare earth elements deposits, and identifying and quantifying our nation's rare earth elements resources have become priorities. Carbonatite and alkaline intrusive complexes, as well as their weathering products, are the primary sources of rare earth elements. The general mineral deposit model summarized here is part of an effort by the U.S. Geological Survey's Mineral Resources Program to update existing models and develop new descriptive mineral deposit models to supplement previously published models for use in mineral-resource and mineral-environmental assessments. Carbonatite and alkaline intrusion-related REE deposits are discussed together because of their spatial association, common enrichment in incompatible elements, and similarities in genesis. A wide variety of commodities have been exploited from carbonatites and alkaline igneous rocks, such as rare earth elements, niobium, phosphate, titanium, vermiculite, barite, fluorite, copper, calcite, and zirconium. Other enrichments include manganese, strontium, tantalum, thorium, vanadium, and uranium.

Core-Mantle Partitioning of Volatile Siderophile Elements and the Origin of Volatile Elements in the Earth

NASA Technical Reports Server (NTRS)

Nickodem, K.; Righter, K.; Danielson, L.; Pando, K.; Lee, C.

2012-01-01

There are currently several hypotheses on the origin of volatile siderophile elements in the Earth. One hypothesis is that they were added during Earth s accretion and core formation and mobilized into the metallic core [1], others claim multiple stage origin [2], while some hypothesize that volatiles were added after the core already formed [3]. Several volatile siderophile elements are depleted in Earth s mantle relative to the chondrites, something which continues to puzzle many scientists. This depletion is likely due to a combination of volatility and core formation. The Earth s core is composed of Fe and some lighter constituents, although the abundances of these lighter elements are unknown [4]. Si is one of these potential light elements [5] although few studies have analyzed the effect of Si on metal-silicate partitioning, in particular the volatile elements. As, In, Ge, and Sb are trace volatile siderophile elements which are depleted in the mantle but have yet to be extensively studied. The metal-silicate partition coefficients of these elements will be measured to determine the effect of Si. Partition coefficients depend on temperature, pressure, oxygen fugacity, and metal and silicate composition and can constrain the concentrations of volatile, siderophile elements found in the mantle. Reported here are the results from 13 experiments examining the partitioning of As, In, Ge, and Sb between metallic and silicate liquid. These experiments will examine the effect of temperature, and metal-composition (i.e., Si content) on these elements in or-der to gain a greater understanding of the core-mantle separation which occurred during the Earth s early stages. The data can then be applied to the origin of volatile elements in the Earth.

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

PubMed

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

2016-09-01

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

Scarcity of rare earth elements.

PubMed

de Boer, M A; Lammertsma, K

2013-11-01

Rare earth elements (REEs) are important for green and a large variety of high-tech technologies and are, therefore, in high demand. As a result, supply with REEs is likely to be disrupted (the degree of depends on the REE) in the near future. The 17 REEs are divided into heavy and light REEs. Other critical elements besides REEs, identified by the European Commission, are also becoming less easily available. Although there is no deficiency in the earth's crust of rare earth oxides, the economic accessibility is limited. The increased demand for REEs, the decreasing export from China, and geopolitical concerns on availability contributed to the (re)opening of mines in Australia and the USA and other mines are slow to follow. As a result, short supply of particularly terbium, dysprosium, praseodymium, and neodymium is expected to be problematic for at least the short term, also because they cannot be substituted. Recycling REEs from electronic waste would be a solution, but so far there are hardly any established REE recycling methods. Decreasing the dependency on REEs, for example, by identifying possible replacements or increasing their efficient use, represents another possibility. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Genome-wide analysis of ABA-responsive elements ABRE and CE3 reveals divergent patterns in Arabidopsis and rice

PubMed Central

Gómez-Porras, Judith L; Riaño-Pachón, Diego Mauricio; Dreyer, Ingo; Mayer, Jorge E; Mueller-Roeber, Bernd

2007-01-01

Background In plants, complex regulatory mechanisms are at the core of physiological and developmental processes. The phytohormone abscisic acid (ABA) is involved in the regulation of various such processes, including stomatal closure, seed and bud dormancy, and physiological responses to cold, drought and salinity stress. The underlying tissue or plant-wide control circuits often include combinatorial gene regulatory mechanisms and networks that we are only beginning to unravel with the help of new molecular tools. The increasing availability of genomic sequences and gene expression data enables us to dissect ABA regulatory mechanisms at the individual gene expression level. In this paper we used an in-silico-based approach directed towards genome-wide prediction and identification of specific features of ABA-responsive elements. In particular we analysed the genome-wide occurrence and positional arrangements of two well-described ABA-responsive cis-regulatory elements (CREs), ABRE and CE3, in thale cress (Arabidopsis thaliana) and rice (Oryza sativa). Results Our results show that Arabidopsis and rice use the ABA-responsive elements ABRE and CE3 distinctively. Earlier reports for various monocots have identified CE3 as a coupling element (CE) associated with ABRE. Surprisingly, we found that while ABRE is equally abundant in both species, CE3 is practically absent in Arabidopsis. ABRE-ABRE pairs are common in both genomes, suggesting that these can form functional ABA-responsive complexes (ABRCs) in Arabidopsis and rice. Furthermore, we detected distinct combinations, orientation patterns and DNA strand preferences of ABRE and CE3 motifs in rice gene promoters. Conclusion Our computational analyses revealed distinct recruitment patterns of ABA-responsive CREs in upstream sequences of Arabidopsis and rice. The apparent absence of CE3s in Arabidopsis suggests that another CE pairs with ABRE to establish a functional ABRC capable of interacting with transcription

Genome-wide analysis of ABA-responsive elements ABRE and CE3 reveals divergent patterns in Arabidopsis and rice.

PubMed

Gómez-Porras, Judith L; Riaño-Pachón, Diego Mauricio; Dreyer, Ingo; Mayer, Jorge E; Mueller-Roeber, Bernd

2007-08-01

In plants, complex regulatory mechanisms are at the core of physiological and developmental processes. The phytohormone abscisic acid (ABA) is involved in the regulation of various such processes, including stomatal closure, seed and bud dormancy, and physiological responses to cold, drought and salinity stress. The underlying tissue or plant-wide control circuits often include combinatorial gene regulatory mechanisms and networks that we are only beginning to unravel with the help of new molecular tools. The increasing availability of genomic sequences and gene expression data enables us to dissect ABA regulatory mechanisms at the individual gene expression level. In this paper we used an in-silico-based approach directed towards genome-wide prediction and identification of specific features of ABA-responsive elements. In particular we analysed the genome-wide occurrence and positional arrangements of two well-described ABA-responsive cis-regulatory elements (CREs), ABRE and CE3, in thale cress (Arabidopsis thaliana) and rice (Oryza sativa). Our results show that Arabidopsis and rice use the ABA-responsive elements ABRE and CE3 distinctively. Earlier reports for various monocots have identified CE3 as a coupling element (CE) associated with ABRE. Surprisingly, we found that while ABRE is equally abundant in both species, CE3 is practically absent in Arabidopsis. ABRE-ABRE pairs are common in both genomes, suggesting that these can form functional ABA-responsive complexes (ABRCs) in Arabidopsis and rice. Furthermore, we detected distinct combinations, orientation patterns and DNA strand preferences of ABRE and CE3 motifs in rice gene promoters. Our computational analyses revealed distinct recruitment patterns of ABA-responsive CREs in upstream sequences of Arabidopsis and rice. The apparent absence of CE3s in Arabidopsis suggests that another CE pairs with ABRE to establish a functional ABRC capable of interacting with transcription factors. Further studies will be

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

PubMed

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

2012-03-01

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

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

NASA Astrophysics Data System (ADS)

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

Evaluation of carbonate diagenesis: A comparative study of minor elements, trace elements, and rare-earth elements (REE + Y) between Pleistocene corals and matrices from Grand Cayman, British West Indies

NASA Astrophysics Data System (ADS)

Li, Rong; Jones, Brian

2014-12-01

On Grand Cayman, the Pleistocene Ironshore Formation consists of six unconformity-bounded units of limestones that have been partially or completely altered to calcite by post-depositional meteoric diagenesis. In order to examine the diagenetic history from the perspective of geochemical elements, the concentrations of minor element (Sr, Na, Mg), trace elements (Ba, Fe, Mn, Al, Si), and rare-earth elements (REE) and yttrium (Y) were determined for 105 corals and 84 matrices collected from the Rogers Wreck Point (RWP), Western Onshore area (WO), and offshore George Town (GT) areas. With the transformation of aragonite to calcite, the Sr, Na, and Ba values decreased, but Mg increased, which are indicative of diagenetic alteration in an open water system. Due to intrinsic "vital effects" and the extrinsic diagenetic environment, the variations of Sr, Na, Ba, and Mg concentrations between Acropora and Montastrea from the GT area are different to those of their counterparts from RWP and WO. The signatures of Sr, Na, Ba, and Mg are in good agreement with the diagenetic history as determined from petrographic and stable isotopic criteria. The REE + Y (REY) concentrations (ΣREY) are higher in the matrices (0.2-6.9 ppm, average 2.6 ppm) than in the associated corals (0.1-5.4 ppm, average 0.6 ppm). Shale-normalized REY patterns of the Pleistocene Ironshore Formation are similar to those of oxygenated seawater, which are characterized by (1) light REE depletion relative to heavy REE (average DySN/SmSN = 1.7, n = 35), (2) positive La anomalies (average Pr/Pr* = 1.17, n = 53), and (3) negative Ce anomalies (average Ce/Ce* = 0.49, n = 53). The preserved seawater-like REY distribution pattern, the lack of correlation between ΣREY and mineralogy, and the lack of correlation between ΣREY and diagenesis-sensitive stable oxygen isotope (δ18O) indicate that meteoric diagenesis did not have a major impact on the REY distribution patterns. The matrices and corals in the GT area

Structural and photoluminescence properties of Ce, Dy, Er-doped ZnO nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jayachandraiah, C.; Kumar, K. Siva; Krishnaiah, G., E-mail: ginnerik@gmail.com

2015-06-24

Undoped ZnO and rare earth elements (Ce, Dy and Er with 2 at. %) doped nanoparticles were synthesized by wet chemical co-precipitation method at 90°C with Polyvinylpyrrolidone (PVP) as capping agent. The structural, morphological, compositional and photoluminescence studies were performed with X-ray diffraction (XRD), Transmission electron microscopy (TEM), Energy dispersive spectroscopy (EDS), FTIR spectroscopy and Photoluminescence (PL) respectively. XRD results revealed hexagonal wurtzite structure with average particle size around 18 nm - 14 nm and are compatible with TEM results. EDS confirm the incorporation of Ce, Dy and Er elements into the host ZnO matrix and is validated by FTIR analysis. PLmore » studies showed a broad intensive emission peak at 558 nm in all the samples. The intensity for Er- doped ZnO found maximum with additional Er shoulder peaks at 516nm and 538 nm. No Ce, Dy emission centers were found in spectra.« less

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

PubMed

Yang, Xiuli; Zhang, Junwei; Fang, Xihui

2014-08-30

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

Synthesis, structure and properties of bimetallic sodium rare-earth (RE) borohydrides, NaRE(BH4)4, RE = Ce, Pr, Er or Gd.

PubMed

Payandeh GharibDoust, SeyedHosein; Ravnsbæk, Dorthe B; Černý, Radovan; Jensen, Torben R

2017-10-10

Formation, stability and properties of new metal borohydrides within RE(BH 4 ) 3 -NaBH 4 , RE = Ce, Pr, Er or Gd is investigated. Three new bimetallic sodium rare-earth borohydrides, NaCe(BH 4 ) 4 , NaPr(BH 4 ) 4 and NaEr(BH 4 ) 4 are formed based on an addition reaction between NaBH 4 and halide free rare-earth metal borohydrides RE(BH 4 ) 3 , RE = Ce, Pr, Er. All the new compounds crystallize in the orthorhombic crystal system. NaCe(BH 4 ) 4 has unit cell parameters of a = 6.8028(5), b = 17.5181(13), c = 7.2841(5) Å and space group Pbcn. NaPr(BH 4 ) 4 is isostructural to NaCe(BH 4 ) 4 with unit cell parameters of a = 6.7617(2), b = 17.4678(7), c = 7.2522(3) Å. NaEr(BH 4 ) 4 crystallizes in space group Cmcm with unit cell parameters of a = 8.5379(2), b = 12.1570(4), c = 9.1652(3) Å. The structural relationships, also to the known RE(BH 4 ) 3 , are discussed in detail and related to the stability and synthesis conditions. Heat treatment of NaBH 4 -Gd(BH 4 ) 3 mixture forms an unstable amorphous phase, which decomposes after one day at RT. NaCe(BH 4 ) 4 and NaPr(BH 4 ) 4 show reversible hydrogen storage capacity of 1.65 and 1.04 wt% in the fourth H 2 release, whereas that of NaEr(BH 4 ) 4 continuously decreases. This is mainly assigned to formation of metal hydrides and possibly slower formation of sodium borohydride. The dehydrogenated state clearly contains rare-earth metal borides, which stabilize boron in the dehydrogenated state.

Anthropogenic disturbance of element cycles at the Earth's surface.

PubMed

Sen, Indra S; Peucker-Ehrenbrink, Bernhard

2012-08-21

The extent to which humans are modifying Earth's surface chemistry can be quantified by comparing total anthropogenic element fluxes with their natural counterparts (Klee and Graedel, 2004). We quantify anthropogenic mass transfer of 77 elements from mining, fossil fuel burning, biomass burning, construction activities, and human apportionment of terrestrial net primary productivity, and compare it to natural mass transfer from terrestrial and marine net primary productivity, riverine dissolved and suspended matter fluxes to the ocean, soil erosion, eolian dust, sea-salt spray, cosmic dust, volcanic emissions, and for helium, hydrodynamic escape from the Earth's atmosphere. We introduce an approach to correct for losses during industrial processing of elements belonging to geochemically coherent groups, and explicitly incorporate uncertainties of element mass fluxes through Monte Carlo simulations. We find that at the Earth's surface anthropogenic fluxes of iridium, osmium, helium, gold, ruthenium, antimony, platinum, palladium, rhenium, rhodium and chromium currently exceed natural fluxes. For these elements mining is the major factor of anthropogenic influence, whereas petroleum burning strongly influences the surficial cycle of rhenium. Our assessment indicates that if anthropogenic contributions to soil erosion and eolian dust are considered, anthropogenic fluxes of up to 62 elements surpass their corresponding natural fluxes.

Electron traps in Gd3Ga3Al2O12:Ce garnets doped with rare-earth ions

NASA Astrophysics Data System (ADS)

Khanin, V. M.; Rodnyi, P. A.; Wieczorek, H.; Ronda, C. R.

2017-05-01

The curves of thermally stimulated luminescence of Gd3Ga3Al2O12:Ce3+ ceramics (a nominally pure sample and samples doped with rare-earth ions) are measured in the temperature range of 80-550 K. The depth and the frequency factor of electron traps established by Eu and Yb impurities are determined. An energy-level diagram of rare-earth ions in the bandgap of Gd3Ga3Al2O12 is presented.

The influence of different alkaline earth oxides on the structural and optical properties of undoped, Ce-doped, Sm-doped, and Sm/Ce co-doped lithium alumino-phosphate glasses

NASA Astrophysics Data System (ADS)

Othman, H. A.; Arzumanyan, G. M.; Möncke, D.

2016-12-01

Undoped, singly Sm doped, Ce doped, and Sm/Ce co-doped lithium alumino-phosphate glasses with different alkaline earth modifiers were prepared by melt quenching. The structure of the prepared glasses was investigated by FT-IR and Raman, as well as by optical spectroscopy. The effect of the optical basicity of the host glass matrix on the added active dopants was studied, as was the effect doping had on the phosphate structural units. The optical edge shifts toward higher wavelengths with an increase in the optical basicity due to the increased polarizability of the glass matrix, but also with increasing CeO2 concentration as a result of Ce3+/Ce4+ inter valence charge transfer (IV-CT) absorption. The optical band gap for direct and indirect allowed transitions was calculated for the undoped glasses. The glass sample containing Mg2+ modifier ions is found to have the highest value (4.16 eV) for the optical band gap while Ba2+ has the lowest value (3.61 eV). The change in the optical band gap arises from the structural changes and the overall polarizability (optical basicity). Refractive index, molar refractivity Rm and molar polarizability αm values increase with increasing optical basicity of the glasses. The characteristic absorption peaks of Sm3+ were also investigated. For Sm/Ce co-doped glasses, especially at high concentration of CeO2, the absorption of Ce3+ hinders the high energy absorption of Sm3+ and this effect becomes more obvious with increasing optical basicity.

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

PubMed

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

2010-05-01

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

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

PubMed

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

2017-04-01

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. 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). 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). HREE-associated toxicity affected embryogenesis, fertilization, cytogenetic and redox endpoints showing different toxicities of tested HREEs. Copyright © 2017 Elsevier Inc. All rights reserved.

Rare-earth elements in human colostrum milk.

PubMed

Poniedziałek, Barbara; Rzymski, Paweł; Pięt, Małgorzata; Niedzielski, Przemysław; Mleczek, Mirosław; Wilczak, Maciej; Rzymski, Piotr

2017-11-01

Rare-earth elements (REEs) are used in a growing number of applications, and their release to environment has increased over the decades. Knowledge of REEs in human milk and factors that could possibly influence their concentration is scarce. This study evaluated the concentrations of 16 REEs (Ce, Eu, Er, Gd, La, Nd, Pr, Sc, Sm, Dy, Ho, Lu, Tb, Tm, Y, and Yb) in human colostrum milk collected from Polish women (n = 100) with the ICP-OES technique. The concentrations (mean ± SD) of Pr (41.9 ± 13.2 μg L -1 ), Nd (11.0 ± 4.0 μg L -1 ), La (7.1 ± 5.2 μg L -1 ), and Er (2.2 ± 0.8 μg L -1 ) were found above detection limits. The total mean ± SD concentration of detected REEs was 60.9 ± 17.8 μg L -1 . Current smokers displayed significantly increased Nd concentrations compared to women who had never smoked. No other associations between REEs in colostrum milk and age, diet in pregnancy (food supplement use and frequency of fish, meat, and vegetable consumption) or place of living (urban/rural) were found. This study adds to general understanding of the occurrence and turnover of REEs in women and human fluids.

Core-Mantle Partitioning of Volatile Elements and the Origin of Volatile Elements in Earth and Moon

NASA Technical Reports Server (NTRS)

Righter, Kevin; Pando, K.; Danielson, L.; Nickodem, K.

2014-01-01

Depletions of volatile siderophile elements (VSE; Ga, Ge, In, As, Sb, Sn, Bi, Zn, Cu, Cd) in mantles of Earth and Moon, constrain the origin of volatile elements in these bodies, and the overall depletion of volatile elements in Moon relative to Earth. A satisfactory explanation has remained elusive [1,2]. We examine the depletions of VSE in Earth and Moon and quantify the amount of depletion due to core formation and volatility of potential building blocks. We calculate the composition of the Earth's PUM during continuous accretion scenarios with constant and variable fO2. Results suggest that the VSE can be explained by a rather simple scenario of continuous accretion leading to a high PT metal-silicate equilibrium scenario that establishes the siderophile element content of Earth's PUM near the end of accretion [3]. Core formation models for the Moon explain most VSE, but calculated contents of In, Sn, and Zn (all with Tc < 750 K) are all still too high after core formation, and must therefore require an additional process to explain the depletions in the lunar mantle. We discuss possible processes including magmatic degassing, evaporation, condensation, and vapor-liquid fractionation in the lunar disk.

Evaluation of rare earth elements in groundwater of Lagos and Ogun States, Southwest Nigeria.

PubMed

Ayedun, H; Arowolo, T A; Gbadebo, A M; Idowu, O A

2017-06-01

Rare earth elements in our environment are becoming important because of their utilization in permanent magnets, lamp phosphors, superconductors, rechargeable batteries, catalyst, ceramics and other applications. This study was conducted to evaluate the level of rare earth elements (REE) and the variability of their anomalous behavior in groundwater samples collected from Lagos and Ogun States, Southwest, Nigeria. REE concentrations were determined in 170 groundwater samples using inductively coupled plasma-mass spectrometry, while the physicochemical parameters were determined using standard methods. Lagos State groundwater is enriched with REE [sum REEs range (mean ± SD)]; [0.365-488 (69.5 ± 117)] µg L -1 than Ogun State groundwater [sum REEs range (mean ± SD)]; [1.14-232 (22.6 ± 41.1)] µg L -1 . Boreholes are more enriched with REEs than wells. Significant (P < 0.05) positive correlation (R = Pearson) was recorded in Lagos State groundwater between sum REEs and Fe (R = 0.55). However, there were no significant correlations between sum REEs, pH (R = 0.073) and HCO 3 2- (R = 0.157) in Ogun State groundwater. Chondrite-normalized plot shows that Lagos groundwater exhibits positive Ce anomaly, while Ogun State groundwater does not. The source of REE in Lagos State may be from the ocean and leaching from wastes dumpsites, while the source in Ogun State groundwater may be from the rocks.

The distribution of Sr and REE between diopside and silicate liquid. [Rare Earth Elements

NASA Technical Reports Server (NTRS)

Grutzeck, M.; Kridelbaugh, S.; Weill, D.

1974-01-01

Experimental determination of the distribution coefficients in diopside-liquid pairs for strontium and nine rare-earth elements in the system CaMgSi2O6-NaAlSi3O8-CaAl2Si2O8. In experiments in air at 1265 C it is found that most of the Sr(2+), Eu(2+), and RE(3+) ions substitute for Ca(2+) and, in addition, a coupled substitution of Al(3+) for Si(4+) occurs. All of the trace ions considered are found to be excluded from the diopside lattice relative to the liquid. In the case of the trivalent ions the exclusion is much more pronounced for La and Ce, which have ionic radii larger than that of Ca(2+) in 8-fold oxygen coordination. Divalent Sr and Eu with even larger radii are also strongly excluded.

Earth, Air, Fire and Water in Our Elements

ERIC Educational Resources Information Center

Lievesley, Tara

2007-01-01

The idea that everything is made of the four "elements", earth, air, fire and water, goes back to the ancient Greeks. In this article, the author talks about the origins of ideas about the elements. The author provides an account that attempts to summarise thousands of years of theoretical development of the elements in a thousand words or so.

The elemental abundances (with uncertainties) of the most Earth-like planet

NASA Astrophysics Data System (ADS)

Wang, Haiyang S.; Lineweaver, Charles H.; Ireland, Trevor R.

2018-01-01

To first order, the Earth as well as other rocky planets in the Solar System and rocky exoplanets orbiting other stars, are refractory pieces of the stellar nebula out of which they formed. To estimate the chemical composition of rocky exoplanets based on their stellar hosts' elemental abundances, we need a better understanding of the devolatilization that produced the Earth. To quantify the chemical relationships between the Earth, the Sun and other bodies in the Solar System, the elemental abundances of the bulk Earth are required. The key to comparing Earth's composition with those of other objects is to have a determination of the bulk composition with an appropriate estimate of uncertainties. Here we present concordance estimates (with uncertainties) of the elemental abundances of the bulk Earth, which can be used in such studies. First we compile, combine and renormalize a large set of heterogeneous literature values of the primitive mantle (PM) and of the core. We then integrate standard radial density profiles of the Earth and renormalize them to the current best estimate for the mass of the Earth. Using estimates of the uncertainties in i) the density profiles, ii) the core-mantle boundary and iii) the inner core boundary, we employ standard error propagation to obtain a core mass fraction of 32.5 ± 0.3 wt%. Our bulk Earth abundances are the weighted sum of our concordance core abundances and concordance PM abundances. Unlike previous efforts, the uncertainty on the core mass fraction is propagated to the uncertainties on the bulk Earth elemental abundances. Our concordance estimates for the abundances of Mg, Sn, Br, B, Cd and Be are significantly lower than previous estimates of the bulk Earth. Our concordance estimates for the abundances of Na, K, Cl, Zn, Sr, F, Ga, Rb, Nb, Gd, Ta, He, Ar, and Kr are significantly higher. The uncertainties on our elemental abundances usefully calibrate the unresolved discrepancies between standard Earth models under

Fast and simultaneously determination of light and heavy rare earth elements in monazite using combination of ultraviolet-visible spectrophotometry and multivariate analysis

NASA Astrophysics Data System (ADS)

Anggraeni, Anni; Arianto, Fernando; Mutalib, Abdul; Pratomo, Uji; Bahti, Husein H.

2017-05-01

Rare Earth Elements (REE) are elements that a lot of function for life, such as metallurgy, optical devices, and manufacture of electronic devices. Sources of REE is present in the mineral, in which each element has similar properties. Currently, to determining the content of REE is used instruments such as ICP-OES, ICP-MS, XRF, and HPLC. But in each instruments, there are still have some weaknesses. Therefore we need an alternative analytical method for the determination of rare earth metal content, one of them is by a combination of UV-Visible spectrophotometry and multivariate analysis, including Principal Component Analysis (PCA), Principal Component Regression (PCR), and Partial Least Square Regression (PLS). The purpose of this experiment is to determine the content of light and medium rare earth elements in the mineral monazite without chemical separation by using a combination of multivariate analysis and UV-Visible spectrophotometric methods. Training set created 22 variations of concentration and absorbance was measured using a UV-Vis spectrophotometer, then the data is processed by PCA, PCR, and PLSR. The results were compared and validated to obtain the mathematical equation with the smallest percent error. From this experiment, mathematical equation used PLS methods was better than PCR after validated, which has RMSE value for La, Ce, Pr, Nd, Gd, Sm, Eu, and Tb respectively 0.095; 0.573; 0.538; 0.440; 3.387; 1.240; 1.870; and 0.639.

Uncovering the end uses of the rare earth elements.

PubMed

Du, Xiaoyue; Graedel, T E

2013-09-01

The rare earth elements (REE) are a group of fifteen elements with unique properties that make them indispensable for a wide variety of emerging and conventional established technologies. However, quantitative knowledge of REE remains sparse, despite the current heightened interest in future availability of the resources. Mining is heavily concentrated in China, whose monopoly position and potential restriction of exports render primary supply vulnerable to short term disruption. We have drawn upon the published literature and unpublished materials in different languages to derive the first quantitative annual domestic production by end use of individual rare earth elements from 1995 to 2007. The information is illustrated in Sankey diagrams for the years 1995 and 2007. Other years are available in the supporting information. Comparing 1995 and 2007, the production of the rare earth elements in China, Japan, and the US changed dramatically in quantities and structure. The information can provide a solid foundation for industries, academic institutions and governments to make decisions and develop strategies. Copyright © 2013 Elsevier B.V. All rights reserved.

Accumulation of rare earth elements in human bone within the lifespan.

PubMed

Zaichick, Sofia; Zaichick, Vladimir; Karandashev, Vasilii; Nosenko, Sergey

2011-02-01

For the first time, the contents of rare earth elements (REEs) in a rib bone of a healthy human were determined. The mean value of the contents of Ce, Dy, Er, Gd, La, Nd, Pr, Sm, Tb, and Yb (10 elements out of 17 total REEs), as well as the upper limit of means for Ho, Lu, Tm, and Y (4 elements) were measured in the rib bone tissue of 38 females and 42 males (15 to 55 years old) using inductively coupled plasma mass spectrometry (ICP-MS). We found age-related accumulation of REEs in the bone tissue of healthy individuals who lived in a non-industrial region. It was calculated that during a lifespan the content of REEs in a skeleton of non-industrial region residents may increase by one to two orders of magnitude. Using our results as indicative normal values and published data we estimated relative Gd accumulation in the bone tissue of patients according to magnetic resonance imaging with contrast agent and La accumulation in the bone tissue of patients receiving hemodialysis after treatment with lanthanum carbonate as a phosphate binder. It was shown that after such procedures contents of Gd and La in the bone tissue of patients are two to three orders of magnitude higher than normal levels. In our opinion, REEs incorporation may affect bone quality and health similar to other potentially toxic trace metals. The impact of elevated REEs content on bone physiology, biochemistry and morphology requires further investigation.

Comparative toxicities of selected rare earth elements: Sea urchin embryogenesis and fertilization damage with redox and cytogenetic effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pagano, Giovanni, E-mail: gbpagano@tin.it; Guida, Marco; Siciliano, Antonietta

Background: Broad-ranging adverse effects are known for rare earth elements (REE), yet only a few studies tested the toxicity of several REE, prompting studies focusing on multi-parameter REE toxicity. Methods: Trichloride salts of Y, La, Ce, Nd, Sm, Eu and Gd were tested in Paracentrotus lividus sea urchin embryos and sperm for: (1) developmental defects in either REE-exposed larvae or in the offspring of REE-exposed sperm; (2) fertilization success; (3) mitotic anomalies in REE-exposed embryos and in the offspring of REE-exposed sperm, and (4) reactive oxygen species (ROS) formation, and malondialdehyde (MDA) and nitric oxide (NO) levels. Results: REEs affectedmore » P. lividus larvae with concentration-related increase in developmental defects, 10{sup −6} to 10{sup −4} M, ranking as: Gd(III)>Y(III)>La(III)>Nd(III)≅Eu(III)>Ce(III)≅Sm(III). Nominal concentrations of REE salts were confirmed by inductively coupled plasma mass spectrometry (ICP-MS). Significant increases in MDA levels, ROS formation, and NO levels were found in REE-exposed embryos. Sperm exposure to REEs (10{sup −5} to 10{sup −4} M) resulted in concentration-related decrease in fertilization success along with increase in offspring damage. Decreased mitotic activity and increased aberration rates were detected in REE-exposed embryos and in the offspring of REE-exposed sperm. Conclusion: REE-associated toxicity affecting embryogenesis, fertilization, cytogenetic and redox endpoints showed different activities of tested REEs. Damage to early life stages, along with redox and cytogenetic anomalies should be the focus of future REE toxicity studies. - Highlights: • Seven rare earth elements exerted different effects on sea urchin early life stages. • Embryo-, spermio- and mitotoxicity, and oxidative/ nitrosative stress were found. • Nominal vs. analytical REE concentrations were checked. • Comparative toxicities were evaluated for the different REE.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pete McGrail

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

Ce isotope systematics of island arc lavas from the Lesser Antilles

NASA Astrophysics Data System (ADS)

Bellot, Nina; Boyet, Maud; Doucelance, Régis; Pin, Christian; Chauvel, Catherine; Auclair, Delphine

2015-11-01

The La-Ce systematics has one of the longest half-lifes (T1/2 = 292.5 Ga) of radioactive decay systems used in isotope geochemistry. Variations of the 138Ce/142Ce ratio are expected to be small and the use of Ce as isotopic tracer requires a very precise measurement. Compared to Sm-Nd studies, the La-Ce decay system can provide additional information about the nature of sediments recycled in subduction zones, because unusually large Ce anomalies relative to the neighboring rare earth elements exist in marine sediments such as fish teeth or hydrothermal deposits. Here, we present a chemical purification technique for Ce, and mass spectrometric technique to perform accurate and reproducible analyses of Ce isotopes of natural samples. We report a large set of Ce isotope data including analysis of 2 Ce reference material solutions (AMES and JMC-304), 2 rock standards (BCR-2 and BHVO-2), 2 chondrites (the carbonaceous chondrite Allende and the enstatite chondrite Sahara 97072), 4 mid-ocean ridge basalts, 30 arc lavas from the Martinique Island and 5 oceanic sediments from DSDP-site 144 drilled on the Demerara rise. The long-term, external precision obtained on the AMES reference material is 80 ppm (2 s.d., 138Ce/142Ce = 0.0225732 ± 18, n = 89). However, we note an evolution of isotopic ratios measured in static mode over the duration of this study (33 months). When the reproducibility is calculated from the AMES reference material measured during the same analytical session, it averages 40 ppm. All the 138Ce/142Ce ratios have been normalized to the AMES value of 0.0225746 (measured in session 7, 2 s.d. = 14 ppm, n = 8), a session during which the chondritic value has been defined and the peak tailing was negligible. The 138Ce/142Ce ratio measured for the JMC-304 Ce reference reagent is 0.0225706 ± 9 (2 s.d. = 38 ppm, n = 10). The analytical precision on natural samples is improved by a factor of about 4 in relation to previous studies on island arcs (Tanaka et al

Comparison of the partitioning behaviours of yttrium, rare earth elements, and titanium between hydrogenetic marine ferromanganese crusts and seawater

USGS Publications Warehouse

Bau, M.; Koschinsky, A.; Dulski, P.; Hein, J.R.

1996-01-01

In order to evaluate details of the partitioning behaviours of Y, rare earth elements (REEs), and Ti between inorganic metal oxide surfaces and seawater, we studied the distribution of these elements in hydrogenetic marine ferromanganese (Fe-Mn) crusts from the Central Pacific Ocean. Nonphosphatized Fe-Mn crusts display shale-normalized rare earths and yttrium (REYSN) patterns (Y inserted between Dy and Ho) that are depleted in light REEs (LREEs) and which show negative anomalies for YSN, and positive anomalies for LaSN, EuSN, GdSN, and in most cases, CeSN. They show considerably smaller Y/ Ho ratios than seawater or common igneous and clastic rocks, indicating that Y and Ho are fractionated in the marine environment. Compared to P-poor crusts, REYSN patterns of phosphatized Fe-Mn crusts are similar, but yield pronounced positive YSN anomalies, stronger positive LaSN anomalies, and enrichment of the HREEs relative to the MREEs. The data suggest modification of REY during phosphatization and indicate that studies requiring primary REY distributions or isotopic ratios should be restricted to nonphosphatized (layers of) Fe-Mn crusts. Apparent bulk coefficients, KMD, describing trace metal partitioning between nonphosphatized hydrogenetic Fe-Mn crusts and seawater, are similar for Pr to Eu and decrease for Eu to Yb. Exceptionally high values of KCeD, which are similar to those of Ti, result from oxidative scavenging of Ce and support previous suggestions that Ce(IV) is a hydroxide-dominated element in seawater. Yttrium and Gd show lower KD values than their respective neighbours in the REY series. Results of modelling the exchange equilibrium between REY dissolved in seawater and REY sorbed on hydrous Fe-Mn oxides corroborate previous studies that suggested the surface complexation of REY can be approximated by their first hydroxide binding constant. Negative "anomalies" occur for stabilities of bulk surface complexes of Gd, La, and particularly Y. The differences in

Rare earth elements in the water column of Lake Vanda, McMurdo Dry Valleys, Antarctica

NASA Astrophysics Data System (ADS)

De Carlo, Eric Heinen; Green, William J.

2002-04-01

We present data on the composition of water from Lake Vanda, Antarctica. Vanda and other lakes in the McMurdo Dry Valleys of Antarctica are characterized by closed basins, permanent ice covers, and deep saline waters. The meromictic lakes provide model systems for the study of trace metal cycling owing to their pristine nature and the relative simplicity of their biogeochemical systems. Lake Vanda, in the Wright Valley, is supplied by a single input, the Onyx River, and has no output. Water input to the lake is balanced by sublimation of the nearly permanent ice cap that is broken only near the shoreline during the austral summer. The water column is characterized by an inverse thermal stratification of anoxic warm hypersaline water underlying cold oxic freshwater. Water collected under trace-element clean conditions was analyzed for its dissolved and total rare earth element (REE) concentrations by inductively coupled plasma mass spectrometry. Depth profiles are characterized by low dissolved REE concentrations (La, Ce, <15 pM) in surface waters that increase slightly (La, 70 pM; Ce, 20 pM) with increasing depth to ∼55 m, the limit of the fresh oxic waters. Below this depth, a sharp increase in the concentrations of strictly trivalent REE (e.g., La, 5 nM) is observed, and a submaximum in redox sensitive Ce (2.6 nM) is found at 60- to 62-m depth. At a slightly deeper depth, a sharper Ce maximum is observed with concentrations exceeding 11 nM at a 67-m depth, immediately above the anoxic zone. The aquatic concentrations of REE reported here are ∼50-fold higher than previously reported for marine oxic/anoxic boundaries and are, to our knowledge, the highest ever observed at natural oxic/anoxic interfaces. REE maxima occur within stable and warm saline waters. All REE concentrations decrease sharply in the sulfidic bottom waters. The redox-cline in Lake Vanda is dominated by diffusional processes and vertical transport of dissolved species driven by concentration

Solvent Extraction of Rare Earth Elements from a Nitric Acid Leach Solution of Apatite by Mixtures of Tributyl Phosphate and Di-(2-ethylhexyl) Phosphoric Acid

NASA Astrophysics Data System (ADS)

Ferdowsi, Ali; Yoozbashizadeh, Hossein

2017-12-01

Solvent extraction of rare earths from nitrate leach liquor of apatite using mixtures of tributyl phosphate (TBP) and di-(2-ethylhexyl) phosphoric acid (D2EHPA) was studied. The effects of nitrate and hydrogen ion concentration of the aqueous phase as well as the composition and concentration of extractants in the organic phase on the extraction behavior of lanthanum, cerium, neodymium, and yttrium were investigated. The distribution ratio of REEs increases by increasing the nitrate concentration in aqueous phase and concentration of extractants in organic phase, but the hydrogen ion concentration in aqueous phase has a decreasing effect. Yttrium as a heavy rare earth is more sensitive to these parameters than light rare earth elements. Although the composition of organic phase has a minor effect on the extraction of light rare earths, the percent of extraction of yttrium decreases dramatically by increasing the TBP content of organic phase. Mixtures of TBP and D2EHPA can show either synergism or antagonism extraction depending on the concentration and composition of extractants in organic phase. The best condition for separating rare earth elements in groups of heavy and light REEs can be achieved at high nitrate concentration, low H+ concentration, and high concentration of D2EHPA in organic phase. Separation of Ce and La by TBP and D2EHPA is practically impossible in the studied conditions; however, low nitrate concentration and high hydrogen ion concentration in aqueous phase and low concentration of extractants in organic phase favor the separation of Nd from other light rare earth elements.

Health risk assessment of rare earth elements in cereals from mining area in Shandong, China.

PubMed

Zhuang, Maoqiang; Wang, Liansen; Wu, Guangjian; Wang, Kebo; Jiang, Xiaofeng; Liu, Taibin; Xiao, Peirui; Yu, Lianlong; Jiang, Ying; Song, Jian; Zhang, Junli; Zhou, Jingyang; Zhao, Jinshan; Chu, Zunhua

2017-08-29

To investigate the concentrations of rare earth elements in cereals and assess human health risk through cereal consumption, a total of 327 cereal samples were collected from rare earth mining area and control area in Shandong, China. The contents of 14 rare earth elements were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The medians of total rare earth elements in cereals from mining and control areas were 74.22 μg/kg and 47.83 μg/kg, respectively, and the difference was statistically significant (P < 0.05). The wheat had the highest rare earth elements concentrations (109.39 μg/kg and 77.96 μg/kg for mining and control areas, respectively) and maize had the lowest rare earth elements concentrations (42.88 μg/kg and 30.25 μg/kg for mining and control areas, respectively). The rare earth elements distribution patterns for both areas were characterized by enrichment of light rare earth elements. The health risk assessment demonstrated that the estimated daily intakes of rare earth elements through cereal consumption were considerably lower than the acceptable daily intake (70 μg/kg bw). The damage to adults can be neglected, but more attention should be paid to the effects of continuous exposure to rare earth elements on children.

Rare earth elements in pore waters from Cabo Friós western boundary upwelling system

NASA Astrophysics Data System (ADS)

Smoak, J. M.; Silva-Filho, E. V.; Rousseau, T.; Albuquerque, A. L.; Caldeira, P. P.; Moreira, M.

2015-12-01

Rare earth elements (REE) are a group of reactive trace elements in aqueous media, they have a coherent chemical behavior with however a subtle and gradual shift in physicochemical properties allowing their use as tracers of sources and processes. Uncertainties on their oceanic inputs and outputs still remains [Arsouze et al., 2009; Siddall et al., 2008; Tachikawa et al., 2003]. The water-sediment interface were early on identified as a relevant REE source due to the high distribution coefficient between sediments and pore waters [Elderfield and Sholkovitz, 1987] and substantially higher concentration then the water column [Abbott et al., 2015; Haley et al., 2004; Sholkovitz et al., 1989; Soyol-Erdene and Huh, 2013]. Here we present a cross shelf transect of 4 short pore waters REE profiles on a 680 km2 mud bank located in the region of Cabo Frio, Brazil. This study reveals similar trends at the four sites: a REE production zone reflected by a maximum in concentration at the top of the sediment evolving with depth toward a REE consumption zone reflected by a minimum in REE concentrations. PAAS normalized patterns shows 1) a progressive depletion in LREE with depth with HREE/LREE ratios comprised between 1.1 and 1.6 in the 2 first centimeters evolving gradually to ratios comprised between 2.8 and 4.7 above 7 cm 2) A sharp gradient in negative Ce anomaly with Ce/Ce* values reaching 0.3. With maximum Nd concentrations comprised between 780 and 1200 pmol.kg and considering that seawater Nd concentrations of Brazilian shelf bottom waters are comprised between 24 and 50 pmol.Kg-1 we apply the Fick´s First Law of diffusion and estimate that 340 +/- 90 nmol. m-2 Y-1 of Nd is released in the Cabo frio´s mudbank. This flux is in the same order of magnitude of recent estimates by [Abbott et al., 2015] in the slope of Oregon´s margin. Unraveling processes responsible for the REE production zone will help to refine the global REE fluxes estimates.

Determination of rare earth elements in tomato plants by inductively coupled plasma mass spectrometry techniques.

PubMed

Spalla, S; Baffi, C; Barbante, C; Turetta, C; Turretta, C; Cozzi, G; Beone, G M; Bettinelli, M

2009-10-30

In recent years identification of the geographical origin of food has grown more important as consumers have become interested in knowing the provenance of the food that they purchase and eat. Certification schemes and labels have thus been developed to protect consumers and genuine producers from the improper use of popular brand names or renowned geographical origins. As the tomato is one of the major components of what is considered to be the healthy Mediterranean diet, it is important to be able to determine the geographical origin of tomatoes and tomato-based products such as tomato sauce. The aim of this work is to develop an analytical method to determine rare earth elements (RRE) for the control of the geographic origin of tomatoes. The content of REE in tomato plant samples collected from an agricultural area in Piacenza, Italy, was determined, using four different digestion procedures with and without HF. Microwave dissolution with HNO3 + H2O2 proved to be the most suitable digestion procedure. Inductively coupled plasma quadrupole mass spectrometry (ICPQMS) and inductively coupled plasma sector field plasma mass spectrometry (ICPSFMS) instruments, both coupled with a desolvation system, were used to determine the REE in tomato plants in two different laboratories. A matched calibration curve method was used for the quantification of the analytes. The detection limits (MDLs) of the method ranged from 0.03 ng g(-1) for Ho, Tm, and Lu to 2 ng g(-1) for La and Ce. The precision, in terms of relative standard deviation on six replicates, was good, with values ranging, on average, from 6.0% for LREE (light rare earth elements) to 16.5% for HREE (heavy rare earth elements). These detection limits allowed the determination of the very low concentrations of REE present in tomato berries. For the concentrations of REE in tomato plants, the following trend was observed: roots > leaves > stems > berries. Copyright 2009 John Wiley & Sons, Ltd.

Preliminary Study on the Dissolutions of Ce, Nd, Y and La from Mineral Cassiterite by Acid and Alkaline Leaching

NASA Astrophysics Data System (ADS)

Firdiyono, F.; Andriyah, L.; Aini, F. N.; Arini, T.; Lalasari, L. H.

2018-03-01

Rare Earth Metal is a rare element that its availability in nature is very small. In Indonesia, the potential of rare earth metals is generally found as the associated mineral in major commodities, especially gold and alluvial tin. These associated minerals can be processed using a particular technology so that the result is a by-product that can increase the added value of the mineral. This purpose of this research was to investigate the dissolution of Cerium (Ce), Neodymium (Nd), Yttrium (Y) and Lanthanum (La) from mineral cassiterite by leaching process using dilute hydrochloric acid (HCl), sulfate acid (H2SO4) and sodium hydroxide (NaOH). Firstly, cassiterite was grinded to -100 mesh of particle size and characterized by X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF) techniques. Secondly, 10 gram of cassiterite was leached in 100 ml solution of 3.26 N HCl, H2SO4 and NaOH at variation leaching time of 2, 4, 6, 24 and 48 hours in atmospheric conditions. The products were then filtered to separate filtrate and residue of cassiterite. Finally, to investigate the dissolution of Ce, La, Nd and Y, filtrate from dissolved cassiterite was analyzed by Induced Coupled Plasma-Optical Emission Spectrometry (ICP-OES), while to know the chemical composition of cassiterite leached by dilute HCl, H2SO4 and NaOH, residue products of cassiterite was characterized by XRF analysis. The result of ICP-OES analysis showed the dissolution of Ce element higher than Nd, Y and La elements for leaching cassiterite using HCl, H2SO4 and NaOH. The increase of leaching time was accompanied by the rise in the amount of dissolved elements from cassiterite. The result of XRF analysis showed the chemistry composition of Ce, Nd, Y and La elements on residue decreased insignificantly from chemistry composition of cassiterite (raw mineral) in all conditions. However, the dissolution of Ce, La, Nd and Y was insignificant in all conditions.

[Physiological effects of rare earth elements and their application in traditional Chinese medicine].

PubMed

Zhou, Jie; Guo, Lanping; Xiao, Wenjuan; Geng, Yanling; Wang, Xiao; Shi, Xin'gang; Dan, Staerk

2012-08-01

The process in the studies on physiological effects of rare earth elements in plants and their action mechanisms were summarized in the aspects of seed germination, photosynthesis, mineral metabolism and stress resistance. And the applications of rare earth elements in traditional Chinese medicine (TCM) in recent years were also overviewed, which will provide reference for further development and application of rare earth elements in TCM.

Anthropogenic Cycles of Rare Earth Elements

NASA Astrophysics Data System (ADS)

Du, X.; Graedel, T. E.

2009-12-01

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

Multi-objective optimization of chromatographic rare earth element separation.

PubMed

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

2015-10-16

The importance of rare earth elements in modern technological industry grows, and as a result the interest for developing separation processes increases. This work is a part of developing chromatography as a rare earth element processing method. Process optimization is an important step in process development, and there are several competing objectives that need to be considered in a chromatographic separation process. Most studies are limited to evaluating the two competing objectives productivity and yield, and studies of scenarios with tri-objective optimizations are scarce. Tri-objective optimizations are much needed when evaluating the chromatographic separation of rare earth elements due to the importance of product pool concentration along with productivity and yield as process objectives. In this work, a multi-objective optimization strategy considering productivity, yield and pool concentration is proposed. This was carried out in the frame of a model based optimization study on a batch chromatography separation of the rare earth elements samarium, europium and gadolinium. The findings from the multi-objective optimization were used to provide with a general strategy for achieving desirable operation points, resulting in a productivity ranging between 0.61 and 0.75 kgEu/mcolumn(3), h(-1) and a pool concentration between 0.52 and 0.79 kgEu/m(3), while maintaining a purity above 99% and never falling below an 80% yield for the main target component europium. Copyright © 2015 Elsevier B.V. All rights reserved.

Trace Elemental Imaging of Rare Earth Elements Discriminates Tissues at Microscale in Flat Fossils

PubMed Central

Gueriau, Pierre; Mocuta, Cristian; Dutheil, Didier B.; Cohen, Serge X.; Thiaudière, Dominique; Charbonnier, Sylvain; Clément, Gaël; Bertrand, Loïc

2014-01-01

The interpretation of flattened fossils remains a major challenge due to compression of their complex anatomies during fossilization, making critical anatomical features invisible or hardly discernible. Key features are often hidden under greatly preserved decay prone tissues, or an unpreparable sedimentary matrix. A method offering access to such anatomical features is of paramount interest to resolve taxonomic affinities and to study fossils after a least possible invasive preparation. Unfortunately, the widely-used X-ray micro-computed tomography, for visualizing hidden or internal structures of a broad range of fossils, is generally inapplicable to flattened specimens, due to the very high differential absorbance in distinct directions. Here we show that synchrotron X-ray fluorescence spectral raster-scanning coupled to spectral decomposition or a much faster Kullback-Leibler divergence based statistical analysis provides microscale visualization of tissues. We imaged exceptionally well-preserved fossils from the Late Cretaceous without needing any prior delicate preparation. The contrasting elemental distributions greatly improved the discrimination of skeletal elements material from both the sedimentary matrix and fossilized soft tissues. Aside content in alkaline earth elements and phosphorus, a critical parameter for tissue discrimination is the distinct amounts of rare earth elements. Local quantification of rare earths may open new avenues for fossil description but also in paleoenvironmental and taphonomical studies. PMID:24489809

Trace elemental imaging of rare earth elements discriminates tissues at microscale in flat fossils.

PubMed

Gueriau, Pierre; Mocuta, Cristian; Dutheil, Didier B; Cohen, Serge X; Thiaudière, Dominique; Charbonnier, Sylvain; Clément, Gaël; Bertrand, Loïc

2014-01-01

The interpretation of flattened fossils remains a major challenge due to compression of their complex anatomies during fossilization, making critical anatomical features invisible or hardly discernible. Key features are often hidden under greatly preserved decay prone tissues, or an unpreparable sedimentary matrix. A method offering access to such anatomical features is of paramount interest to resolve taxonomic affinities and to study fossils after a least possible invasive preparation. Unfortunately, the widely-used X-ray micro-computed tomography, for visualizing hidden or internal structures of a broad range of fossils, is generally inapplicable to flattened specimens, due to the very high differential absorbance in distinct directions. Here we show that synchrotron X-ray fluorescence spectral raster-scanning coupled to spectral decomposition or a much faster Kullback-Leibler divergence based statistical analysis provides microscale visualization of tissues. We imaged exceptionally well-preserved fossils from the Late Cretaceous without needing any prior delicate preparation. The contrasting elemental distributions greatly improved the discrimination of skeletal elements material from both the sedimentary matrix and fossilized soft tissues. Aside content in alkaline earth elements and phosphorus, a critical parameter for tissue discrimination is the distinct amounts of rare earth elements. Local quantification of rare earths may open new avenues for fossil description but also in paleoenvironmental and taphonomical studies.

Evolution of the atomic order and valence state of rare-earth atoms and uranium in a new carbon-metal composite—diphthalocyanine pyrolysate C64H32N16 Me ( Me = Y, La, Ce, Eu, and U)

NASA Astrophysics Data System (ADS)

Sovestnov, A. E.; Kapustin, V. K.; Tikhonov, V. I.; Fomin, E. V.; Chernenkov, Yu. P.

2014-08-01

The structure of a metal-carbon composite formed by the pyrolysis of diphthalocyanine of some rare-earth elements (Y, La, Ce, Eu) and uranium in the temperature range T ann = 800-1700°C has been investigated for the first time by the methods of X-ray diffraction analysis and X-ray line shift. It has been shown that, in the general case, the studied pyrolysates consist of three phases. One phase corresponds to the structure of graphite. The second phase corresponds to nitrides, carbides, and oxides of basic metal elements with a crystallite size ranging from 5 to 100 nm. The third phase is amorphous or consisting of crystallites with a size of ˜1 nm. It has been found that all the basic elements (Y, La, Ce, Eu, U) and incorporated iodine atoms in the third phase are in a chemically bound state. The previously unobserved electronic configurations have been revealed for europium. The possibility of including not only atoms of elements forming diphthalocyanine but also other elements (for example, iodine) in the composite structure is of interest, in particular, for the creation of a thermally, chemically, and radiation resistant metal-carbon matrix for the radioactive waste storage.

Coal fly ash as a resource for rare earth elements.

PubMed

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

2015-06-01

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

Rare earth elements in human hair from a mining area of China.

PubMed

Wei, Binggan; Li, Yonghua; Li, Hairong; Yu, Jiangping; Ye, Bixiong; Liang, Tao

2013-10-01

Rare earth minerals have been mined for more than 50 years in Inner Mongolia of China. In the mining area rare earth elements (REE) may be significantly accumulated in humans. Therefore, the aim of this paper is to characterize the REE concentrations in hair of local residents. REE concentrations in hair of 118 subjects were determined. The results showed that the mean concentrations of the determined REE in the hair of both females and males were usually higher from mining area than from control area. The mean concentrations of all the fifteen REE were much higher in hair of males than in hair of females from mining area. This suggested that males might be more sensitive to REE than females. In addition, the mean contents of the REE in hair of miners, particularly light REE (La, Ce, Pr and Nd), were usually much higher than the values in hair of non-miners from both mining area and control area, indicating that the miners were exposed to higher concentrations of REE in occupational environment. Among age groups, the relationships between REE concentrations and age groups showed that more and more concentrations of light REE accumulated in body of both females and males with age until 60 years, while heavy REE concentrations decreased with age in males who were exposed to low concentrations of heavy REE. Copyright © 2013 Elsevier Inc. All rights reserved.

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

NASA Astrophysics Data System (ADS)

Showstack, Randy

2012-03-01

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

Rare earth and trace element geochemistry of a fragment of Jurassic seafloor, Point Sal, California

NASA Technical Reports Server (NTRS)

Menzies, M.; Blanchard, D.; Brannon, J.; Korotev, R.

1977-01-01

Rocks from an ophiolite suite once on the seafloor were analyzed for rare earth elements (REE), Sc, Co, Na2O, Cr, Zn and FeO. Strontium isotope exchange noted in some of the lavas is attributed to basalt-seawater interaction; the Ce abundance in smectite- and zeolite-bearing lavas may also be due to prolonged exposure to seawater. The higher grades of metamorphic rock, however, show no variation from the usual flat or slightly light REE depleted profiles. Plutonic igneous rock, all light REE depleted, have total REE abundances varying by a factor of 100 between the dunites and diorites. In order of decreasing REE abundance are hornblende, clinopyroxene, plagioclase, orthopyroxene and olivine. Calculations of REE contents of liquids in equilibrium with early cumulative clinopyroxenes suggest that the parent to the stratiform sequence was more depleted in light REE than the parent to the lava pile.

Substitutional alloy of Ce and Al

PubMed Central

Zeng, Qiao-Shi; Ding, Yang; Mao, Wendy L.; Luo, Wei; Blomqvist, Andreas; Ahuja, Rajeev; Yang, Wenge; Shu, Jinfu; Sinogeikin, Stas V.; Meng, Yue; Brewe, Dale L.; Jiang, Jian-Zhong; Mao, Ho-kwang

2009-01-01

The formation of substitutional alloys has been restricted to elements with similar atomic radii and electronegativity. Using high-pressure at 298 K, we synthesized a face-centered cubic disordered alloy of highly dissimilar elements (large Ce and small Al atoms) by compressing the Ce3Al intermetallic compound >15 GPa or the Ce3Al metallic glass >25 GPa. Synchrotron X-ray diffraction, Ce L3-edge absorption spectroscopy, and ab initio calculations revealed that the pressure-induced Kondo volume collapse and 4f electron delocalization of Ce reduced the differences between Ce and Al and brought them within the Hume-Rothery (HR) limit for substitutional alloying. The alloy remained after complete release of pressure, which was also accompanied by the transformation of Ce back to its ambient 4f electron localized state and reversal of the Kondo volume collapse, resulting in a non-HR alloy at ambient conditions. PMID:19188608

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

NASA Astrophysics Data System (ADS)

Kong, Linghang

2017-09-01

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

Catalytic Graphitization of Coal-Based Carbon Materials with Light Rare Earth Elements.

PubMed

Wang, Rongyan; Lu, Guimin; Qiao, Wenming; Yu, Jianguo

2016-08-30

The catalytic graphitization mechanism of coal-based carbon materials with light rare earth elements was investigated using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, selected-area electron diffraction, and high-resolution transmission electron microscopy. The interface between light rare earth elements and carbon materials was carefully observed, and two routes of rare earth elements catalyzing the carbon materials were found: dissolution-precipitation and carbide formation-decomposition. These two simultaneous processes certainly accelerate the catalytic graphitization of carbon materials, and light rare earth elements exert significant influence on the microstructure and thermal conductivity of graphite. Moreover, by virtue of praseodymium (Pr), it was found that a highly crystallographic orientation of graphite was induced and formed, which was reasonably attributed to the similar arrangements of the planes perpendicular to (001) in both graphite and Pr crystals. The interface between Pr and carbon was found to be an important factor for the orientation of graphite structure.

Leaching behavior of rare earth elements in Fort Union lignite coals of North America

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laudal, Daniel A.; Benson, Steven A.; Addleman, Raymond Shane

Rare earth elements are crucial materials in an incredible array of consumer goods, energy system components and military defense applications. However, the global production and entire value chain for rare earth elements is dominated by China, with the U.S. currently 100% import reliant for these critical materials. Traditional mineral ores including those previously mined in the U.S., however, have several challenges. Chief among these is that the content of the most critical and valuable of the rare earths are deficient, making mining uneconomical. Further, the supply of these most critical rare earths is nearly 100% produced in China from amore » single resource that is only projected to last another 10 to 20 years. The U.S. currently considers the rare earths market an issue of national security. It is imperative that alternative domestic sources of rare earths be identified and methods developed to produce them. Recently, coal and coal byproducts have been identified as one of these promising alternative resources. This paper details the results of a study on characterization of North Dakota lignite and lignite-related feedstocks as an assessment of their feasibility for rare earth element recovery. The abundance, distribution and modes of occurrence of the rare earth elements in the samples collected were determined in this initial study to inform the selection of appropriate extraction and concentration methods to recover the rare earth elements. Materials investigated include the lignite coals, clay-rich sediments associated with the coal seams, and materials associated with a lignite beneficiation system and power plant. The results show that high rare earth element levels exist both in lignite coals and associated sediments. The form of the rare earth elements in the clay materials is primarily as ultra-fine mineral grains. In the lignite coals, approximately 80-95% of the rare earths content is organically associated, primarily as coordination

Plasma-assisted adsorption of elemental mercury on CeO2/TiO2 at low temperatures

NASA Astrophysics Data System (ADS)

Liu, Lu; Zheng, Chenghang; Gao, Xiang

2017-11-01

Mercury is a kind of pollutants contained in flue gas which is hazardous for human beings. In this work, CeO2 was packed in the discharge zone of a plasma reactor to adsorb elemental mercury at low temperatures. Plasma-catalyst reactor can remove Hg0 efficiently with CeO2/TiO2 catalysts packed in the discharge zone. The Hg0 concentration continued to decrease gradually when the plasma was turned on, but not sank rapidly. This tendency was different with other catalysts. The treatment of plasma to CeO2/TiO2 catalysts has a promotion effect on the adsorption of Hg0. Plasma has the effect of changing the surface properties of the catalysts and the changes would restitute if the condition changed. The long-running test demonstrated that this method is an effective way to remove Hg0. The removal efficiency remained at above 99% throughout 12 hours when plasma had been turned on (15kV, 0.5 g packed CeO2/TiO2).

Rare earth elements in sinters from the geothermal waters (hot springs) on the Tibetan Plateau, China

NASA Astrophysics Data System (ADS)

Feng, Jin-Liang; Zhao, Zhen-Hong; Chen, Feng; Hu, Hai-Ping

2014-10-01

The mineralogical and geochemical composition of sinters from the geothermal areas on the Tibetan Plateau was determined. They occur as siliceous, salty and calcareous sinters but biogenic siliceous sinters were also found. The analyses indicate that there are no distinct inter -element relationships between individual rare earth elements (REEs) and other elements. Formed from the same geothermal water, the mineralogical and chemical composition of the sinters is influenced by their genesis and formation conditions. The REE distributions depend on the origin of the sinters. Fe-Mn phases in sinters tend to scavenge more REEs from geothermal water. Neither the REE fractionation nor the Ce anomaly seems to be associated with Fe-Mn phases in the sinters. The fourth tetrads of some sinters display weak W-type (concave) effects. In contrast, the third tetrads present large effects in some sinters due to positive Gd anomalies. The origin of the positive Eu anomalies in some sinters seems to be caused by preferential dissolution of feldspars during water-rock interaction. The complexing ligands in geothermal water may contribute significantly to the fractionation of REEs in sinters. The dominant CO32- and HCO3- complexing in geothermal water favors enrichment of heavy REEs in calcareous sinters.

Ce(III) and Ce(IV) (re)distribution and fractionation in a laterite profile from Madagascar: Insights from in situ XANES spectroscopy at the Ce LIII-edge

NASA Astrophysics Data System (ADS)

Janots, Emilie; Bernier, Felix; Brunet, Fabrice; Muñoz, Manuel; Trcera, Nicolas; Berger, Alfons; Lanson, Martine

2015-03-01

The distribution of trivalent and tetravalent cerium, Ce(III) and Ce(IV) respectively, in a lateritic profile from Madagascar, has been characterized by X-ray-absorption near-edge structure (XANES) spectroscopy at the Ce LIII-edge on the LUCIA beamline (SOLEIL synchrotron, France). XANES spectra were acquired on bulk-rock samples as well as on specific lateritic minerals or polymineral zones (in-situ measurements) of the tonalite bedrock and the three overlying weathered horizons (C-, B- and A-horizons). Geochemically, the bedrock, and the A- and C-horizons show similar rare earth element content (REE = 363-405 mg/kg). They also display the same positive Ce-anomaly (CeCN/Ce∗ = 1.12-1.45), which is therefore likely to be inherited from the bedrock. In the B-horizon, the higher REE content (REE = 2194 mg/kg) and the larger Ce-anomaly (CeCN/Ce∗ = 4.26) are consistent with an accumulation zone caused by the evaporation of groundwater during the dry season. There is a good agreement between the Ce(III)/Cetotal ratio (XCe(III)) deduced from the positive Ce-anomaly (bulk-rock geochemical data) and that derived from XANES spectroscopy on the same bulk-rock samples (BR-XCe(III)-XANES) in the bedrock, and the C- and B-horizons. In the A-horizon, XANES measurements on bulk rock and minerals revealed a higher BR-XCe(III)-XANES (up to 100%) compared to the XCe(III) deduced from geochemical data (XCe(III) = 79%). The preservation of a positive Ce-anomaly in the A-horizon suggests that the Ce mobilization and redistribution during weathering occurred with no significant Ce fractionation from other trivalent REE. Remarkably, the only investigated sample where cerianite is observed belongs to the B-horizon. Within this horizon, Ce oxidation state varies depending on the microstructural position (porosity, cracks, clay-rich groundmass). The highest Ce(IV) concentrations are measured in cerianite (and aluminophosphates) localized in pores at the vicinity of Mn-rich domains (XCe

[Distribution characteristic and current situation of soil rare earth contamination in the Bayan Obo mining area and Baotou tailing reservoir in Inner Mongolia].

PubMed

Guo, Wei; Fu, Rui-ying; Zhao, Ren-xin; Zhao, Wen-jing; Guo, Jiang-yuan; Zhang, Jun

2013-05-01

The pollution status and distribution characteristic of rare earth elements in soil were analyzed around Bayan Obo mining area and Baotou tailing reservoir located in Inner Mongolia grassland ecosystem, aiming at grasping the overall situation of grassland ecosystem pollution caused by rare earth elements and providing basic information as well as theoretical basis. The results indicated that seven rare earth elements in soils from different directions of Baotou tailing reservoir accumulated to a certain extent compared to the soil background value of Inner Mongolia. The pollution degree was Ce > La > Nd > Pr > Sm > Y > Eu. Within 50 m from the edge of tailing reservoir, soil rare earth contamination was the most serious, with the concentrations of La, Ce, Pr, Nd, Sm, Eu and Y reaching 11,45.0 mg x kg(-1), 23,636.0 mg x kg(-1), 4568.16 mg x kg(-1) , 6855.51 mg x kg(-1), 582.18 mg x kg(-1), 94.21 mg x kg(-1)), and 136.25 mg x kg(-1), respectively. Owing to the dominant wind direction of northwest, soils from the southeast were contaminated most seriously. For Bayan Obo mining area, the concentrations of seven rare earth elements in soil from the mining area were significantly higher than those of other areas investigated, with the concentrations of La, Ce, Pr, Nd, Sm, Eu and Y reaching 3112.56 mg x kg(-1), 7142.12 mg x kg(-1), 1467.12 mg x kg(-1), 2552.80 mg x kg(-1), 210.80 mg x kg(-1), 36.20 mg x kg(-1) and 63.22 mg x kg(-1), respectively. The soils of six areas of Bayan Obo mining area were all contaminated by rare earth elements, and the contamination degree was in the order of mining area > outside the dump > east side of the railway > the dump > outside the urban area > west side of the railway. Besides, the transportation of rare earth ore led to the soil rare earth contamination along the railway, and the distribution characteristic of rare earth elements in soils along the railway was affected by the dominant wind direction of northwest. Baotou tailing

The elements of the Earth's magnetism and their secular changes between 1550 and 1915

NASA Technical Reports Server (NTRS)

Fritsche, H.

1983-01-01

The results of an investigation about the magnetic agents outside the Earth's surface as well as the Earth's magnetic elements for the epochs 1550, 1900, 1915 are presented. The secular changes of the Earth's magnetic elements during the time interval 1550 - 1900 are also included.

Rare Earth Element Geochemistry for Produced Waters, WY

DOE Data Explorer

Quillinan, Scott; Nye, Charles; McLing, Travis; Neupane, Hari

2016-06-30

These data represent major, minor, trace, isotopes, and rare earth element concentrations in geologic formations and water associated with oil and gas production. *Note - Link below contains updated version of spreadsheet (6/14/2017)

Pyrazolates advance cerium chemistry: a CeIII/CeIV redox equilibrium with benzoquinone.

PubMed

Werner, Daniel; Deacon, Glen B; Junk, Peter C; Anwander, Reiner

2017-05-16

Two stable cerium(iv) 3,5-dialkylpyrazolate complexes are presented, namely dimeric [Ce(Me 2 pz) 4 ] 2 (Me 2 pz = 3,5-dimethylpyrazolate) and monomeric Ce(tBu 2 pz) 4 (tBu 2 pz = 3,5-di-tert-butylpyrazolate) along with their trivalent counterparts [Ce(Me 2 pz) 3 ] and [Ce(tBu 2 pz) 3 ] 2 . All complexes were obtained from protonolysis reactions employing the silylamide precursors Ce[N(SiHMe 2 ) 2 ] 4 and Ce[N(SiMe 3 ) 2 ] 3 . Treatment of homoleptic Ce IV and Ce III Me 2 pz complexes with 1,4-hydroquinone (H 2 hq) or 1,4-benzoquinone (bq), respectively, ultimately gave the same trimetallic Ce III species via a cerium redox equilibrium. The Ce III complex Ce 3 (Me 2 pz) 5 (pchd) 2 (L) (pchd = 1,4-bis(3,5-dimethylpyrazol-1-yl)cyclohex-2,5-diene-1,4-diolato; L = Me 2 pzH or (thf) 2 ) results from a di-1,4-pyrazolyl attack on pre-coordinated bq. The reduction of bq by [Ce(Me 2 pz) 3 (thf)] 2 , and re-oxidation by the resulting Ce IV species was supported by UV-vis spectroscopic investigations. Comparisons with the redox-innocent complexes [Ln(Me 2 pz) 3 (thf)] 2 (Ln = La and Pr) revealed far less selective reactions with bq, giving hexametallic and octametallic rare-earth metal side products containing 2-Me 2 pz substituted hq ligands.

Rare earths and other trace elements in Luna 16 soil.

NASA Technical Reports Server (NTRS)

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

1972-01-01

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

Review of rare earth element concentrations in oil shales of the Eocene Green River Formation

USGS Publications Warehouse

Birdwell, Justin E.

2012-01-01

Concentrations of the lanthanide series or rare earth elements and yttrium were determined for lacustrine oil shale samples from the Eocene Green River Formation in the Piceance Basin of Colorado and the Uinta Basin of Utah. Unprocessed oil shale, post-pyrolysis (spent) shale, and leached shale samples were examined to determine if oil-shale processing to generate oil or the remediation of retorted shale affects rare earth element concentrations. Results for unprocessed Green River oil shale samples were compared to data published in the literature on reference materials, such as chondritic meteorites, the North American shale composite, marine oil shale samples from two sites in northern Tibet, and mined rare earth element ores from the United States and China. The Green River oil shales had lower rare earth element concentrations (66.3 to 141.3 micrograms per gram, μg g-1) than are typical of material in the upper crust (approximately 170 μg g-1) and were also lower in rare earth elements relative to the North American shale composite (approximately 165 μg g-1). Adjusting for dilution of rare earth elements by organic matter does not account for the total difference between the oil shales and other crustal rocks. Europium anomalies for Green River oil shales from the Piceance Basin were slightly lower than those reported for the North American shale composite and upper crust. When compared to ores currently mined for rare earth elements, the concentrations in Green River oil shales are several orders of magnitude lower. Retorting Green River oil shales led to a slight enrichment of rare earth elements due to removal of organic matter. When concentrations in spent and leached samples were normalized to an original rock basis, concentrations were comparable to those of the raw shale, indicating that rare earth elements are conserved in processed oil shales.

[Spectroscopic Research on Slag Nanocrystal Glass Ceramics Containing Rare Earth Elements].

PubMed

Ouyang, Shun-li; Li, Bao-wei; Zhang, Xue-feng; Jia, Xiao-lin; Zhao, Ming; Deng, Lei-bo

2015-08-01

The research group prepared the high-performance slag nanocrystal glass ceramics by utilizing the valuable elements of the wastes in the Chinese Bayan Obo which are characterized by their symbiotic or associated existence. In this paper, inductively coupled plasma emission spectroscopy (ICP), X-ray diffraction (XRD), Raman spectroscopy (Raman) and scanning electron microscopy (SEM) are all used in the depth analysis for the composition and structure of the samples. The experiment results of ICP, XRD and SEM showed that the principal crystalline phase of the slag nanocrystal glass ceramics containing rare earth elements is diopside, its grain size ranges from 45 to 100 nm, the elements showed in the SEM scan are basically in consistent with the component analysis of ICP. Raman analysis indicated that its amorphous phase is a three-dimensional network structure composed by the structural unit of silicon-oxy tetrahedron with different non-bridging oxygen bonds. According to the further analysis, we found that the rare earth microelement has significant effect on the network structure. Compared the nanocrystal slag glass ceramic with the glass ceramics of similar ingredients, we found that generally, the Raman band wavenumber for the former is lower than the later. The composition difference between the glass ceramics and the slag nanocrystal with the similar ingredients mainly lies on the rare earth elements and other trace elements. Therefore, we think that the rare earth elements and other trace elements remains in the slag nanocrystal glass ceramics have a significant effect on the network structure of amorphous phase. The research method of this study provides an approach for the relationship among the composition, structure and performance of the glass ceramics.

Evaluation of Rare Earth Element Extraction from North Dakota Coal-Related Feed Stocks

NASA Astrophysics Data System (ADS)

Laudal, Daniel A.

The rare earth elements consist of the lanthanide series of elements with atomic numbers from 57-71 and also include yttrium and scandium. Due to their unique properties, rare earth elements are crucial materials in an incredible array of consumer goods, energy system components and military defense applications. However, the global production and entire value chain for rare earth elements is dominated by China, with the U.S. currently 100% import reliant for these critical materials. Traditional mineral ores including previously mined deposits in the U.S., however, have several challenges. Chief among these is that the content of the most critical and valuable of the rare earths are deficient, making mining uneconomical. Further, the supply of these most critical rare earths is nearly 100% produced in China from a single resource that is only projected to last another 10 to 20 years. The U.S. currently considers the rare earths market an issue of national security. It is imperative that alternative domestic sources of rare earths be identified and methods developed to produce them. Recently, coal and coal byproducts have been identified as one of these promising alternative resources. This dissertation details a study on evaluation of the technical and economic feasibility of rare earth element recovery from North Dakota lignite coal and lignite-related feedstocks. There were four major goals of this study: i) identify lignite or lignite-related feedstocks with total rare earth element content above 300 parts per million, a threshold dictated by the agency who funded this research as the minimum for economic viability, ii) determine the geochemistry of the feedstocks and understand the forms and modes of occurrence of the rare earth elements, information necessary to inform the development of extraction and concentration methods, iii) identify processing methods to concentrate the rare earth elements from the feedstocks to a target of two weight percent, a value

Extraction of rare earth elements from low-grade Bauxite via precipitation reaction

NASA Astrophysics Data System (ADS)

Kusrini, E.; Nurani, Y.; Bahari, ZJ

2018-03-01

The aim of this research was to determine the optimum hydrometallurgical parameters to extract the rare earth elements (REE) from low-grade bauxite through acid leaching and precipitation reaction. REE or lanthanide recovery by a precipitation method with sodium sulphate and sodium phosphate as precipitation agents is reported where the effect of pH and recovery of REE are described. The metal composition of REE in low-grade bauxite after treatment were analyzed by ICP-OES. The total recovery values of REE elements at the first precipitation reaction using sodium sulphate as the precipitation agent at pH 3.5 showed ~68.2% of lanthanum, ~18.9% cerium, and ~7.8% yttrium. Lanthanum was the rare-earth element present at the highest concentration in the low-grade bauxite after the series treatments. An optimum pH of 3.5 for precipitation of rare-earth elements using sodium sulphate was demonstrated where this method is recommended for the extraction of REE elements from low-grade bauxite.

Geochemistry of rare earth elements within waste rocks from the Montviel carbonatite deposit, Québec, Canada.

PubMed

Edahbi, Mohamed; Plante, Benoît; Benzaazoua, Mostafa; Pelletier, Mia

2018-04-01

Several rare earth element (REE) mine projects around the world are currently at the feasibility stage. Unfortunately, few studies have evaluated the contamination potential of REE and their effects on the environment. In this project, the waste rocks from the carbonatites within the Montviel proterozoic alkaline intrusion (near Lebel-sur-Quévillon, Quebec, Canada) are assessed in this research. The mineralization is mainly constituted by light REE (LREE) fluorocarbonates (qaqarssukite-Ce, kukharenkoite-Ce), LREE carbonates (burbankite, Sr-Ba-Ca-REE, barytocalcite, strontianite, Ba-REE-carbonates), and phosphates (apatite, monazite). The gangue minerals are biotites, chlorite, albite, ankerite, siderite, and calcite. The SEM-EDS analyses show that (i) the majority of REE are associated with the fine fraction (< 106 μm), (ii) REE are mainly associated with carbonates, (iii) all analyzed minerals preferably contain LREE (La, Ce, Pr, Nd, Sm, Eu), (iv) the sum of LREE in each analyzed mineral varies between ~ 3 and 10 wt%, (v) the heavy REE (HREE) identified are Gd and Yb at < 0.4 wt%, and (vi) three groups of carbonate minerals were observed containing variable concentrations of Ca, Na, and F. Furthermore, the mineralogical composition of REE-bearing minerals, REE mobility, and REE speciation was investigated. The leachability and geochemical behavior of these REE-bearing mine wastes were tested using normalized kinetic testing (humidity cells). Leachate results displayed higher LREE concentrations, with decreasing shale-normalized patterns. Thermodynamical equilibrium calculations suggest that the precipitation of secondary REE minerals may control the REE mobility.

Processing of spent Ni-MH batteries for the recovery of cobalt, nickel and rare earth elements bearing materials by means of a chemical and electrochemical sequential process

NASA Astrophysics Data System (ADS)

Delvasto, P.; Orta Rodríguez, R.; Blanco, S.

2016-02-01

Rechargeable Ni-MH batteries contain strategic metal values which are worth to be recovered. In the present work, a preliminary sequential chemical and electrochemical procedure is proposed, in order to reclaim materials bearing Ni, Co and rare earth elements (REE) from Ni-MH spent batteries. Initially, spent batteries are disassembled to separate the electrode materials (anode and cathode), which are then leached with an aqueous solution of 5w% sulphuric acid. The metal content of this solution is checked by atomic absorption spectrometry techniques. The obtained solution is pH-adjusted (with NaOH), until pH is between 4.0 and 4.3; then, it is heated up to 70°C to precipitate a rare earth elements sulphate (Nd, La, Pr, Ce), as determined by means of x-ray fluorescence techniques. The solids-free solution is then electrolyzed, in order to recover a Ni-Co alloy. The electrolysis conditions were established through a cyclic voltammetry technique.

NIR emission using Ce3+→Nd3+ energy transfer in Ba3Ce(PO4)3:Nd3+ phosphor

NASA Astrophysics Data System (ADS)

Tumram, P. V.; Moharil, S. V.

2018-05-01

In the System CePO4-Ba3(PO4)2, the intermediate compound Ba3Ce(PO4)3, is well known. In recent years, luminescence of rare earths has been studied in this host. However, there are no reports on the NIR emission in Ba3Ce(PO4)3. Here, NIR emission resulting from Ce3+→Nd3+ energy transfer in Ba3Ce(PO4)3 host is reported. This could be relevant for applications in bioimaging, telecommunication, solar photovoltaics, Photodynamic therapy, photostimulated localized hyperthermia, etc.

Living target of Ce(III) action on horseradish cells: proteins on/in cell membrane.

PubMed

Yang, Guangmei; Sun, Zhaoguo; Lv, Xiaofen; Deng, Yunyun; Zhou, Qing; Huang, Xiaohua

2012-12-01

Positive and negative effects of rare earth elements (REEs) in life have been reported in many papers, but the cellular mechanisms have not been answered, especially the action sites of REEs on plasma membrane are unknown. Proteins on/in the plasma membrane perform main functions of the plasma membrane. Cerium (Ce) is the richest REEs in crust. Thus, the interaction between Ce(III) and the proteins on/in the plasma membrane, the morphology of protoplast, and the contents of nutrient elements in protoplast of horseradish were investigated using the optimized combination of the fluorescence microscopy, fluorescence spectroscopy, circular dichroism, scanning electron microscopy, and X-ray energy dispersive spectroscopy. It was found that Ce(III) at the low concentrations (10, 30 μM) could interact with proteins on/in the plasma membrane of horseradish, leading to the improvement in the structure of membrane proteins and the plasma membrane, which accelerated the intra-/extra-cellular substance exchange and further promoted the development of cells. When horseradish was treated with Ce(III) at the high concentrations (60, 80 μM), Ce(III) also could interact with the proteins on/in the plasma membrane of horseradish, leading to the destruction in the structure of membrane proteins and the plasma membrane. These effects decelerated the intra-/extra-cellular substance exchange and further inhibited the development of cells. Thus, the interaction between Ce(III) and proteins on/in the plasma membrane in plants was an important reason of the positive and negative effects of Ce(III) on plants. The results would provide some references for understanding the cellular effect mechanisms of REEs on plants.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oral, Rahime

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)more » 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

Deep-sea mud in the Pacific Ocean as a potential resource for rare-earth elements

NASA Astrophysics Data System (ADS)

Kato, Yasuhiro; Fujinaga, Koichiro; Nakamura, Kentaro; Takaya, Yutaro; Kitamura, Kenichi; Ohta, Junichiro; Toda, Ryuichi; Nakashima, Takuya; Iwamori, Hikaru

2011-08-01

World demand for rare-earth elements and the metal yttrium--which are crucial for novel electronic equipment and green-energy technologies--is increasing rapidly. Several types of seafloor sediment harbour high concentrations of these elements. However, seafloor sediments have not been regarded as a rare-earth element and yttrium resource, because data on the spatial distribution of these deposits are insufficient. Here, we report measurements of the elemental composition of over 2,000 seafloor sediments, sampled at depth intervals of around one metre, at 78 sites that cover a large part of the Pacific Ocean. We show that deep-sea mud contains high concentrations of rare-earth elements and yttrium at numerous sites throughout the eastern South and central North Pacific. We estimate that an area of just one square kilometre, surrounding one of the sampling sites, could provide one-fifth of the current annual world consumption of these elements. Uptake of rare-earth elements and yttrium by mineral phases such as hydrothermal iron-oxyhydroxides and phillipsite seems to be responsible for their high concentration. We show that rare-earth elements and yttrium are readily recovered from the mud by simple acid leaching, and suggest that deep-sea mud constitutes a highly promising huge resource for these elements.

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

NASA Astrophysics Data System (ADS)

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

2014-11-01

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

Electro-kinetic Separation of Rare Earth Elements Using a Redox-Active Ligand.

PubMed

Fang, Huayi; Cole, Bren E; Qiao, Yusen; Bogart, Justin A; Cheisson, Thibault; Manor, Brian C; Carroll, Patrick J; Schelter, Eric J

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 6 H 4 CH 2 } 3 N] 3- . Using this method, a single-step separation factor up to 261 was obtained for the separation of a 50:50 yttrium-lutetium mixture. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of supplementing rare earth element cerium on rumen fermentation, nutrient digestibility, nitrogen balance and plasma biochemical parameters in beef cattle.

PubMed

Lin, S X; Wei, C; Zhao, G Y; Zhang, T T; Yang, K

2015-12-01

The objectives of the trial were to investigate the effects of supplementing rare earth element (REE) cerium (Ce) on rumen fermentation, nutrient digestibility, methane (CH4 ) production, nitrogen (N) balance and plasma biochemical parameters in beef cattle. Four Simmental male cattle, aged at 14 months, with initial liveweight of 355 ± 8 kg and fitted with permanent rumen cannulas, were used as experimental animals. The cattle were fed with a total mixed ration (TMR) composed of concentrate mixture and corn silage. Four levels of cerium chloride (CeCl3 ·7H2 O, purity 99.9%), that is 0, 80, 160 and 240 mg CeCl3 /kg DM, were added to basal ration in a 4 × 4 Latin square design. Each experimental period lasted 15 days, of which the first 12 days were for pre-treatment and the last 3 days were for sampling. The results showed that supplementing CeCl3 at 160 or 240 mg/kg DM increased neutral detergent fibre (NDF) digestibility (p < 0.05) and tended to increased acid detergent fibre (ADF) digestibility (p = 0.083). Supplementing CeCl3 at 80, 160 or 240 mg/kg DM decreased the molar ratio of rumen acetate to propionate linearly (p < 0.05). Supplementing CeCl3 at 160 or 240 mg/kg DM decreased total N excretion, urinary N excretion and increased N retention (p < 0.05), increased excretion of total urinary purine derivatives (PD) (p < 0.05) and decreased CH4 /kg DMI (p < 0.05). In conclusion, supplementing CeCl3 at 160 or 240 mg/kg DM in the ration of beef cattle increased the digestibility of NDF, decreased the molar ratio of rumen acetate to propionate, increased N retention and microbial N flow and decreased CH4 /kg DMI. Journal of Animal Physiology and Animal Nutrition © 2015 Blackwell Verlag GmbH.

Assessing rare earth elements in quartz rich geological samples.

PubMed

Santoro, A; Thoss, V; Ribeiro Guevara, S; Urgast, D; Raab, A; Mastrolitti, S; Feldmann, J

2016-01-01

Sodium peroxide (Na2O2) fusion coupled to Inductively Coupled Plasma Tandem Mass Spectrometry (ICP-MS/MS) measurements was used to rapidly screen quartz-rich geological samples for rare earth element (REE) content. The method accuracy was checked with a geological reference material and Instrumental Neutron Activation Analysis (INAA) measurements. The used mass-mode combinations presented accurate results (only exception being (157)Gd in He gas mode) with recovery of the geological reference material QLO-1 between 80% and 98% (lower values for Lu, Nd and Sm) and in general comparable to INAA measurements. Low limits of detection for all elements were achieved, generally below 10 pg g(-1), as well as measurement repeatability below 15%. Overall, the Na2O2/ICP-MS/MS method proved to be a suitable lab-based method to quickly and accurately screen rock samples originating from quartz-rich geological areas for rare earth element content; particularly useful if checking commercial viability. Copyright © 2015 Elsevier Ltd. All rights reserved.

Ternary rare earth sulfide CaCe2S4: Synthesis and characterization of stability, structure, and photoelectrochemical properties in aqueous media

NASA Astrophysics Data System (ADS)

Sotelo, Paola; Orr, Melissa; Galante, Miguel Tayar; Hossain, Mohammad Kabir; Firouzan, Farinaz; Vali, Abbas; Li, Jun; Subramanian, Mas; Longo, Claudia; Rajeshwar, Krishnan; Macaluso, Robin T.

2018-06-01

A red-orange rare earth ternary chalcogenide, CaCe2S4, was prepared in powder form by solid-state synthesis. The structural details of this compound were determined by powder X-ray diffraction. The optical band gap of CaCe2S4 was determined by diffuse reflectance spectroscopy (DRS) to be 2.1 eV, consistent with the observed red-orange color. Quantitative colorimetry measurements also support the observed color and band gap of CaCe2S4. Both direct and indirect optical transitions were gleaned from Tauc analyses of the DRS data. Photoelectrochemistry experiments on CaCe2S4 films showed n-type semiconductor behavior. Analyses of these data via the Butler-Gärtner model afforded a flat-band potential of - 0.33 V (vs. Ag/AgCl/KCl 4 M) in pH 9 aqueous sulfite electrolyte. The potential and limitations of this material for solar water splitting and photocatalytic environmental remediation (e.g., dye photodegradation) are finally presented against the backdrop of its photoelectrochemical stability and surface hole transfer kinetics in aqueous electrolytes.

Rare Earth Element Concentrations in Submarine Hydrothermal Fluids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fowler, Andrew; Zierenberg, Robert

Rare earth element concentrations in submarine hydrothermal fluids from Alarcon Rise, East Pacific Rise, REE concentrations in submarine hydrothermal fluids from Pescadero Basin, Gulf of California, and the Cleft vent field, southern Juan de Fuca Ridge. Data are not corrected to zero Mg.

Anomalous abundance and redistribution patterns of rare earth elements in soils of a mining area in Inner Mongolia, China.

PubMed

Wang, Lingqing; Liang, Tao

2016-06-01

The Bayan Obo Mine, the largest rare earth element (REE) deposit ever found in the world, has been mined for nearly 60 years for iron and rare earth elements. To assess the influences of mining activities on geochemical behavior of REEs in soils, 27 surface soil samples and three soil profile samples were collected from different directions in the vicinity of the mine area. The total concentrations of REEs in surface soils varied from 149.75 to 18,891.81 mg kg(-1) with an average value of 1906.12 mg kg(-1), which was apparently higher than the average values in China (181 mg kg(-1)). The order of the average concentrations of individual REEs in surface soils was similar to that in Bayan Obo ores, which confirmed that the concentration and distribution of REEs in the soils was influenced by the mining activities. The concentrations of single REE in the soil profiles showed a similar trend with depth with an increase at 0-25 cm section, then decreased and remained relatively stable in the deep part. The normalized curves inclined to the right side, showing the conspicuous fractionation between the light and heavy REEs, which supported by the North American Shale Composite (NASC) and Post-Archean Australian Shale (PAAS) normalized concentration ratios calculated for selected elements (La N /Yb N , La N /Sm N , Gd N /Yb N ). Slight positive Ce anomaly and negative Eu anomaly were also observed.

Geochemical prospecting for rare earth elements using termite mound materials

NASA Astrophysics Data System (ADS)

Horiuchi, Yu; Ohno, Tetsuji; Hoshino, Mihoko; Shin, Ki-Cheol; Murakami, Hiroyasu; Tsunematsu, Maiko; Watanabe, Yasushi

2014-12-01

The Blockspruit fluorite prospect, located in North West State of the Republic of South Africa, occurs within an actinolite rock zone that was emplaced into the Kenkelbos-type granite of Proterozoic age. There are a large number of termite mounds in the prospect. For geochemical prospecting for rare earth elements (REEs), in total, 200 samples of termite mound material were collected from actinolite rock and granite zones in the prospect. Geochemical analyses of these termite mound materials were conducted by two methods: portable X-ray fluorescence (XRF) spectrometry and inductively coupled plasma-mass spectrometry (ICP-MS). Comparison of the two methods broadly indicates positive correlations of REEs (La, Ce, Pr, Nd, and Y), in particular Y and La having a strong correlation. As the result of modal abundance analyses, the actinolite rock at surface mainly consists of ferro-actinolite (89.89 wt%) and includes xenotime (0.26 wt%) and monazite (0.21 wt%) grains as REE minerals. Termite mound materials from actinolite rock also contain xenotime (0.27 wt%) and monazite (0.41 wt%) grains. In addition, termite mound materials from the actinolite rock zone have high hematite and Fe silicate contents compared to those from granite zone. These relationships suggest that REE minerals in termite mound materials originate form actinolite rock. Geochemical anomaly maps of Y, La, and Fe concentrations drawn based on the result of the portable XRF analyses show that high concentrations of these elements trend from SW to NE which broadly correspond to occurrences of actinolite body. These results indicate that termite mounds are an effective tool for REE geochemical prospection in the study area for both light REEs and Y, but a more detailed survey is required to establish the distribution of the actinolite rock body.

Volatile elements - water, carbon, nitrogen, noble gases - on Earth

NASA Astrophysics Data System (ADS)

Marty, B.

2017-12-01

Understanding the origin and evolution of life-bearing volatile elements (water, carbon, nitrogen) on Earth is a fruitful and debated area of research. In his pioneering work, W.W. Rubey inferred that the terrestrial atmosphere and the oceans formed from degassing of the mantle through geological periods of time. Early works on noble gas isotopes were consistent with this view and proposed a catastrophic event of mantle degassing early in Earth's history. We now have evidence, mainly from noble gas isotopes, that several cosmochemical sources contributed water and other volatiles at different stages of Earth's accretion. Potential contributors include the protosolar nebula gas that equilibrated with magma oceans, inner solar system bodies now represented by chondrites, and comets. Stable isotope ratios suggest volatiles where primarily sourced by planetary bodies from the inner solar system. However, recent measurements by the European Space Agency Rosetta probe on the coma of Comet 67P/Churyumov-Gerasimenko permit to set quantitative constraints on the cometary contribution to the surface of our planet. The surface and mantle reservoirs volatile elements exchanged volatile elements through time, with rates that are still uncertain. Some mantle regions remained isolated from whole mantle convection within the first tens to hundreds million years after start of solar system formation. These regions, now sampled by some mantle plumes (e.g., Iceland, Eifel) preserved their volatile load, as indicated by extinct and extant radioactivity systems. The abundance of volatile elements in the mantle is still not well known. Different approaches, such as high pressure experimental petrology, noble gas geochemistry, modelling, resulted in somewhat contrasted estimates, varying over one order of magnitude for water. Comparative planetology, that is, the study of volatiles on the Moon, Venus, Mars, Vesta, will shed light on the sources and strengths of these elements in the

Geochemistry of rare earth elements in a passive treatment system built for acid mine drainage remediation.

PubMed

Prudêncio, Maria Isabel; Valente, Teresa; Marques, Rosa; Sequeira Braga, Maria Amália; Pamplona, Jorge

2015-11-01

Rare earth elements (REE) were used to assess attenuation processes in a passive system for acid mine drainage treatment (Jales, Portugal). Hydrochemical parameters and REE contents in water, soils and sediments were obtained along the treatment system, after summer and winter. A decrease of REE contents in the water resulting from the interaction with limestone after summer occurs; in the wetlands REE are significantly released by the soil particles to the water. After winter, a higher water dynamics favors the AMD treatment effectiveness and performance since REE contents decrease along the system; La and Ce are preferentially sequestered by ochre sludge but released to the water in the wetlands, influencing the REE pattern of the creek water. Thus, REE fractionation occurs in the passive treatment systems and can be used as tracer to follow up and understand the geochemical processes that promote the remediation of AMD. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

PubMed

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

2017-02-01

To investigate the concentrations of rare earth elements in vegetables and assess human health risk through vegetable consumption, a total of 301 vegetable samples were collected from mining area and control area in Shandong, China. The contents of 14 rare earth elements were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The total rare earth elements in vegetables from mining and control areas were 94.08 μg kg -1 and 38.67 μg kg -1 , respectively, and the difference was statistically significant (p < 0.05). The leaf vegetable had the highest rare earth elements concentration (984.24 μg kg -1 and 81.24 μg kg -1 for mining and control areas, respectively) and gourd vegetable had the lowest rare earth elements concentration (37.34 μg kg -1 and 24.63 μg kg -1 for mining and control areas, respectively). For both areas, the rare earth elements concentration in vegetables declined in the order of leaf vegetable > taproot vegetable > alliaceous vegetable > gourd vegetable. The rare earth elements distribution patterns for both areas were characterized by enrichment of light rare earth elements. The health risk assessment demonstrated that the estimated daily intakes (0.69 μg kg -1 d -1 and 0.28 μg kg -1 d -1 for mining and control areas, respectively) of rare earth elements through vegetable consumption were significantly lower than the acceptable daily intake (70 μg kg -1 d -1 ). The damage to adults can be neglected, but more attention should be paid to the effects of continuous exposure to low levels of rare earth elements on children. Copyright © 2016 Elsevier Ltd. All rights reserved.

Rare earth elements in freshwater, marine, and terrestrial ecosystems in the eastern Canadian Arctic.

PubMed

MacMillan, Gwyneth Anne; Chételat, John; Heath, Joel P; Mickpegak, Raymond; Amyot, Marc

2017-10-18

Few ecotoxicological studies exist for rare earth elements (REEs), particularly field-based studies on their bioaccumulation and food web dynamics. REE mining has led to significant environmental impacts in several countries (China, Brazil, U.S.), yet little is known about the fate and transport of these contaminants of emerging concern. Northern ecosystems are potentially vulnerable to REE enrichment from prospective mining projects at high latitudes. To understand how REEs behave in remote northern food webs, we measured REE concentrations and carbon and nitrogen stable isotope ratios (∂ 15 N, ∂ 13 C) in biota from marine, freshwater, and terrestrial ecosystems of the eastern Canadian Arctic (N = 339). Wildlife harvesting and tissue sampling was partly conducted by local hunters through a community-based monitoring project. Results show that REEs generally follow a coherent bioaccumulation pattern for sample tissues, with some anomalies for redox-sensitive elements (Ce, Eu). Highest REE concentrations were found at low trophic levels, especially in vegetation and aquatic invertebrates. Terrestrial herbivores, ringed seal, and fish had low total REE levels in muscle tissue (∑REE for 15 elements <0.1 nmol g -1 ), yet accumulation was an order of magnitude higher in liver tissues. Age- and length-dependent REE accumulation also suggest that REE uptake is faster than elimination for some species. Overall, REE bioaccumulation patterns appear to be species- and tissue-specific, with limited potential for biomagnification. This study provides novel data on the behaviour of REEs in ecosystems and will be useful for environmental impact assessment of REE enrichment in northern regions.

Game meat authentication through rare earth elements fingerprinting.

PubMed

Danezis, G P; Pappas, A C; Zoidis, E; Papadomichelakis, G; Hadjigeorgiou, I; Zhang, P; Brusic, V; Georgiou, C A

2017-10-23

Accurate labelling of meat (e.g. wild versus farmed, geographical and genetic origin, organic versus conventional, processing treatment) is important to inform the consumers about the products they buy. Meat and meat products declared as game have higher commercial value making them target to fraudulent labelling practices and replacement with non-game meat. We have developed and validated a new method for authentication of wild rabbit meat using elemental metabolomics approach. Elemental analysis was performed using rapid ultra-trace multi-element measurement by inductively coupled plasma mass spectrometry (ICP-MS). Elemental signatures showed excellent ability to discriminate the wild rabbit from non-wild rabbit meat. Our results demonstrate the usefulness of metabolic markers -rare earth signatures, as well as other trace element signatures for game meat authentication. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of rare earth and concomitant elements in magnesium alloys by inductively coupled plasma optical emission spectrometry.

PubMed

Fariñas, Juan C; Rucandio, Isabel; Pomares-Alfonso, Mario S; Villanueva-Tagle, Margarita E; Larrea, María T

2016-07-01

An Inductively Coupled Plasma Optical Emission Spectrometry method for simultaneous determination of Al, Ca, Cu, Fe, In, Mn, Ni, Si, Sr, Y, Zn, Zr and rare earth elements (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) in magnesium alloys, including the new rare earth elements-alloyed magnesium, has been developed. Robust conditions have been established as nebulizer argon flow rate of 0.5mLmin(-1) and RF incident power of 1500W, in which matrix effects were significantly reduced around 10%. Three acid digestion procedures were performed at 110°C in closed PFA vessels heated in an oven, in closed TFM vessels heated in a microwave furnace, and in open polypropylene tubes with reflux caps heated in a graphite block. The three digestion procedures are suitable to put into solution the magnesium alloys samples. From the most sensitive lines, one analytical line with lack or low spectral interferences has been selected for each element. Mg, Rh and Sc have been studied as internal standards. Among them, Rh was selected as the best one by using Rh I 343.488nm and Rh II 249.078nm lines as a function of the analytical lines. The trueness and precision have been established by using the Certified Reference Material BCS 316, as well as by means of recovery studies. Quantification limits were between 0.1 and 9mgkg(-1) for Lu and Pr, respectively, in a 2gL(-1) magnesium matrix solution. The method developed has been applied to the commercial alloys AM60, AZ80, ZK30, AJ62, WE54 and AE44. Copyright © 2016 Elsevier B.V. All rights reserved.

Spectroscopic identification of rare earth elements in phosphate glass

NASA Astrophysics Data System (ADS)

Devangad, Praveen; Tamboli, Maktum; Muhammed Shameem, K. M.; Nayak, Rajesh; Patil, Ajeetkumar; Unnikrishnan, V. K.; Santhosh, C.; Kumar, G. A.

2018-01-01

In this work, rare earth-doped phosphate glasses were synthesized and characterized using three different spectroscopic techniques. The absorption spectra of the prepared praseodymium (Pr) and samarium (Sm) doped glasses, recorded by a UV-VIS-NIR spectrophotometer, show the characteristic absorption bands of these elements. To confirm this inference, laser-induced fluorescence spectra of Pr and Sm were obtained at a laser excitation of 442 nm. Their emission bands are reported here. The elemental analysis of these samples was carried out using a laser-induced breakdown spectroscopy (LIBS) system. Characteristic emission lines of Pr and Sm have been identified and reported by the recorded LIBS spectra of glass samples. Results prove that using these three complimentary spectroscopic techniques (absorption, fluorescence and LIBS), we can meaningfully characterize rare earth-doped glass samples.

Assessing anthropogenic levels, speciation, and potential mobility of rare earth elements (REEs) in ex-tin mining area.

PubMed

Khan, Aysha Masood; Yusoff, Ismail; Bakar, Nor Kartini Abu; Bakar, Ahmad Farid Abu; Alias, Yatimah

2016-12-01

A study was carried out to determine the level of rare earth elements (REEs) in water and sediment samples from ex-mining lakes and River in Kinta Valley, Perak, Malaysia. Surface water and sediments from an ex-mining lake and Kinta River water samples were analyzed for REEs by inductively coupled plasma mass spectrometry. The total concentration of REEs in the ex-mining lake water samples and sediments were found to be 3685 mg/l and 14159 mg/kg, respectively, while the total concentration of REEs in Kinta River water sample was found to be 1224 mg/l. REEs in mining lake water were found to be within 2.42 mg/l (Tb) to 46.50 mg/l (Ce), while for the Kinta River, it was 1.33 mg/l (Ho) to 29.95 mg/l (Ce). Sediment samples were also found with REEs from 9.81 mg/kg (Ho) to 765.84 mg/kg (Ce). Ce showed the highest average concentrations for mining lake (3.88 to 49.08 mg/l) and Kinta River (4.44 to 33.15 mg/l) water samples, while the concentration of La was the highest (11.59 to 771.61 mg/kg) in the mining lake sediment. Lu was shown to have the highest enrichment of REEs in ex-mining lake sediments (107.3). Multivariate statistical analyses such as factor analysis and principal component analysis indicated that REEs were associated and controlled by mixed origin, with similar contributions from anthropogenic and geogenic sources. The speciation study of REEs in ex-tin mining sediments using a modified five-stage sequential extraction procedure indicated that yttrium (Y), gadolinium (Gd), and lanthanum (La) were obtained at higher percentages from the adsorbed/exchanged/carbonate fraction. The average potential mobility of the REEs was arranged in a descending order: Yb > Gd > Y = Dy > Pr > Er > Tm > Eu > Nd > Tb > Sc > Lu > Ce > La, implying that under favorable conditions, these REEs could be released and subsequently pollute the environment.

Rare earth elements and permanent magnets (invited)

NASA Astrophysics Data System (ADS)

Dent, Peter C.

2012-04-01

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

Scanning Electron Microscope-Cathodoluminescence Analysis of Rare-Earth Elements in Magnets.

PubMed

Imashuku, Susumu; Wagatsuma, Kazuaki; Kawai, Jun

2016-02-01

Scanning electron microscope-cathodoluminescence (SEM-CL) analysis was performed for neodymium-iron-boron (NdFeB) and samarium-cobalt (Sm-Co) magnets to analyze the rare-earth elements present in the magnets. We examined the advantages of SEM-CL analysis over conventional analytical methods such as SEM-energy-dispersive X-ray (EDX) spectroscopy and SEM-wavelength-dispersive X-ray (WDX) spectroscopy for elemental analysis of rare-earth elements in NdFeB magnets. Luminescence spectra of chloride compounds of elements in the magnets were measured by the SEM-CL method. Chloride compounds were obtained by the dropwise addition of hydrochloric acid on the magnets followed by drying in vacuum. Neodymium, praseodymium, terbium, and dysprosium were separately detected in the NdFeB magnets, and samarium was detected in the Sm-Co magnet by the SEM-CL method. In contrast, it was difficult to distinguish terbium and dysprosium in the NdFeB magnet with a dysprosium concentration of 1.05 wt% by conventional SEM-EDX analysis. Terbium with a concentration of 0.02 wt% in an NdFeB magnet was detected by SEM-CL analysis, but not by conventional SEM-WDX analysis. SEM-CL analysis is advantageous over conventional SEM-EDX and SEM-WDX analyses for detecting trace rare-earth elements in NdFeB magnets, particularly dysprosium and terbium.

Rare earth elements in weathering profiles and sediments of Minnesota: Implications for provenance studies

USGS Publications Warehouse

Morey, G.B.; Setterholm, D.R.

1997-01-01

The relative abundance of rare earth elements in sediments has been suggested as a tool for determining their source rocks. This correlation requires that weathering, erosion, and sedimentation do not alter the REE abundances, or do so in a predictable manner. We find that the rare earth elements are mobilized and fractionated by weathering, and that sediments derived from the weathered materials can display modifications of the original pattern of rare earth elements of some due to grain-size sorting of the weathered material. However, the REE distribution pattern of the provenance terrane can be recognized in the sediments.

Sources and distribution of yttrium and rare earth elements in surface sediments from Tagus estuary, Portugal.

PubMed

Brito, Pedro; Prego, Ricardo; Mil-Homens, Mário; Caçador, Isabel; Caetano, Miguel

2018-04-15

The distribution and sources of yttrium and rare-earth elements (YREE) in surface sediments were studied on 78 samples collected in the Tagus estuary (SW Portugal, SW Europe). Yttrium and total REE contents ranged from 2.4 to 32mg·kg -1 and 18 to 210mg·kg -1 , respectively, and exhibited significant correlations with sediment grain-size, Al, Fe, Mg and Mn, suggesting a preferential association to fine-grained material (e.g. aluminosilicates but also Al hydroxides and Fe oxyhydroxides). The PAAS (Post-Archean Australian Shale) normalized patterns display three distinct YREE fractionation pattern groups along the Tagus estuary: a first group, characterized by medium to coarse-grained material, a depleted and almost flat PAAS-normalized pattern, with a positive anomaly of Eu, representing one of the lithogenic components; a second group, characterized mainly by fine-grained sediment, with higher shale-normalized ratios and an enrichment of LREE relative to HREE, associated with waste water treatment plant (WWTP) outfalls, located in the northern margin; and, a third group, of fine-grained material, marked by a significant enrichment of Y, a depletion of Ce and an enrichment of HREE over LREE, located near an inactive chemical-industrial complex (e.g. pyrite roast plant, chemical and phosphorous fertilizer industries), in the southern margin. The data allow the quantification of the YREE contents and its spatial distribution in the surface sediments of the Tagus estuary, identifying the main potential sources and confirming the use of rare earth elements as tracers of anthropogenic activities in highly hydrodynamic estuaries. Copyright © 2017 Elsevier B.V. All rights reserved.

SO2 Adsorption on CeO2(100) and CeO2(111)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mullins, David R.

2016-09-13

The adsorption and reaction of sulfur dioxide, SO2, was studied on oxidized and reduced CeOX(100) and compared to previous results on CeOX(111). SO2 adsorbs on oxidized CeO2(100) as sulfite, SO32-, at 200 K and sulfite is the only adsorbate observed on the surface at any temperature. The sulfite desorbs monotonically from 200 to 700 K. The adsorption and desorption of SO2 does not result in any change in the Ce4+ oxidation state. SO2 also adsorbs as sulfite on reduced CeO1.7(100) at 200 K. There is also a small amount of elemental sulfur, S0, formed. As the sample is heated themore » sulfite decomposes into sulfide, S2-. Roughly 25 % of the adsorbed S either desorbs or diffuses into the bulk of the reduced ceria. The decomposition, and resulting formation of S2- and O2-, re-oxidize some of the Ce3+ to Ce4+. Unlike what has been observed following the adsorption and reaction of many other molecules, the adsorption and reaction of SO2 is virtually identical on CeOX(100) and CeOX(111).« less

Origin of heavy rare earth mineralization in South China

PubMed Central

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

2017-01-01

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

Determination of the Earth's Plasmapause Location from the CE-3 EUVC Images

NASA Technical Reports Server (NTRS)

He, Fei; Zhang, Xiao-Xin; Chen, Bo; Fok, Mei-Ching; Nakano, Shinya

2016-01-01

The Moon-based Extreme Ultraviolet Camera (EUVC) aboard China's Chang'e-3 (CE-3) mission has successfully imaged the entire Earth's plasmasphere for the first time from the side views on lunar surface. An EUVC image on 21 April 2014 is used in this study to demonstrate the characteristics and configurations of the Moon-based EUV imaging and to illustrate the determination algorithm of the plasmapause locations on the magnetic equator. The plasmapause locations determined from all the available EUVC images with the Minimum L Algorithm are quantitatively compared with those extracted from insitu observations (Defense Meteorological Satellite Program, Time History of Events and Macroscale Interactions during Substorms, and Radiation Belt Storm Probes). Excellent agreement between the determined plasmapauses seen by EUVC and the extracted ones from other satellites indicates the reliability of the Moon-based EUVC images as well as the determination algorithm. This preliminary study provides an important basis for future investigation of the dynamics of the plasmasphere with the Moon-based EUVC imaging.

Abnormal variation of magnetic properties with Ce content in (PrNdCe)2Fe14B sintered magnets prepared by dual alloy method

NASA Astrophysics Data System (ADS)

Xue-Feng, Zhang; Jian-Ting, Lan; Zhu-Bai, Li; Yan-Li, Liu; Le-Le, Zhang; Yong-Feng, Li; Qian, Zhao

2016-05-01

Resource-saving (PrNdCe)2Fe14B sintered magnets with nominal composition (PrNd)15-x Ce x Fe77B8 (x = 0-10) were prepared using a dual alloy method by mixing (PrNd)5Ce10Fe77B8 with (PrNd)15Fe77B8 powders. For Ce atomic percent of 1% and 2%, coercivity decreases dramatically. With further increase of Ce atomic percent, the coercivity increases, peaks at 6.38 kOe in (PrNd)11Ce4Fe77B8, and then declines gradually. The abnormal dependence of coercivity is likely related to the inhomogeneity of rare earth chemical composition in the intergranular phase, where PrNd concentration is strongly dependent on the additive amount of (PrNd)5Ce10Fe77B8 powders. In addition, for Ce atomic percent of 8%, 7%, and 6% the coercivity is higher than that of magnets prepared by the conventional method, which shows the advantage of the dual alloy method in preparing high abundant rare earth magnets. Project supported by the National Natural Science Foundation of China (Grant Nos. 51461033, 51571126, 51541105, and 11547032), the Natural Science Foundation of Inner Mongolia, China (Grant No. 2013MS0110), and the Inner Mongolia University of Science and Technology Innovation Fund, China.

Cathodoluminescent characteristics and light technical parameters of thin-film screens based on oxides and oxysulfides of rare-earth elements

NASA Astrophysics Data System (ADS)

Bondar, Vyacheslav D.; Grytsiv, Myroslav; Groodzinsky, Arkady; Vasyliv, Mykhailo

1995-11-01

Results on creation of thin-film single-crystal high-resolution screens with energy control of luminescence color are presented. In order to create phosphor films ion-plasma technology for deposition of yttrium and lanthanum oxides and oxysulfides activated by rare earth elements has been developed. The screen consists of phosphor film on phosphor substrate with different colors of luminescence (e.g. Y2O3-Eu film with red color on Y3Al5O12- Tb, Ce substrate with green color of luminescence). Electron irradiation causes luminescence with color that depends on energy of the electron beam. The physical reason for color change is that electron beam energy defines electron penetration depth. If the energy is weak, only the film is excited. More powerful beam penetrates into the substrate and thus changes the color of luminescence.

Hematite (α-Fe2O3) - A potential Ce4+ carrier in red mud.

PubMed

Bolanz, Ralph M; Kiefer, Stefan; Göttlicher, Jörg; Steininger, Ralph

2018-05-01

Cerium is the most abundant rare earth element (REE) within the waste product of alumina production (red mud), but its speciation in this complex material is still barely understood. Previous studies showed evidence for a correlation between Ce and the main constituent of red mud, iron oxides, which led us to investigate the most abundant iron oxide in red mud, hematite, as possible carrier phase for Ce. Synthetic hematite can incorporate up to 1.70±0.01wt% Ce, which leads to a systematical increase of all unit cell parameters. Investigations by extended X-ray absorption fine structure spectroscopy suggest an incorporation of Ce 4+ O 6 into the hematite structure by a novel atomic arrangement, fundamentally different from the close-range order around Fe 3+ in hematite. Samples of red mud were taken in Lauta (Saxony), Germany and analyzed by powder X-ray diffraction, inductively coupled plasma mass and optical emission spectrometry, electron microprobe analysis and X-ray absorption near-edge structure spectroscopy. Red mud samples consist of hematite (Fe 2 O 3 ) (34-58wt%), sodalite (Na 8 Al 6 Si 6 O 24 Cl 2 ) (4-30wt%), gibbsite (Al(OH) 3 ) (0-25wt%), goethite (FeOOH) (10-23wt%), böhmite (AlOOH) (0-11wt%), rutile (TiO 2 ) (4-8wt%), cancrinite (Na 6 Ca 2 Al 6 Si 6 O 24 (CO 3 ) 2 ) (0-5wt%), nordstrandite (Al(OH) 3 ) (0-5wt%) and quartz (SiO 2 ) (0-4wt%). While the main elemental composition is Fe>Al>Na>Ti>Ca (Si not included), the average concentration of REE is 1109±6mg/kg with an average Ce concentration of 464±3mg/kg. The main carrier of Ce was located in the Fe-rich fine-grained fraction of red mud (0.10wt% Ce 2 O 3 ), while other potential Ce carriers like monazite, lead oxides, secondary Ce-minerals and particles of potentially anthropogenic origin are of subordinated relevance. Cerium in red mud occurs predominantly as Ce 4+ , which further excludes Ce 3+ minerals as relevant sources. Copyright © 2017. Published by Elsevier B.V.

Statistical Constraints from Siderophile Elements on Earth's Accretion, Differentiation, and Initial Core Stratification

NASA Astrophysics Data System (ADS)

O'Rourke, J. G.; Stevenson, D. J.

2015-12-01

Abundances of siderophile elements in the primitive mantle constrain the conditions of Earth's core/mantle differentiation. Core growth occurred as Earth accreted from collisions between planetesimals and larger embryos of unknown original provenance, so geochemistry is directly related to the overall dynamics of Solar System formation. Recent studies claim that only certain conditions of equilibration (pressure, temperature, and oxygen fugacity) during core formation can reproduce the available data. Typical analyses, however, only consider the effects of varying a few out of tens of free parameters in continuous core formation models. Here we describe the Markov chain Monte Carlo method, which simultaneously incorporates the large uncertainties on Earth's composition and the parameterizations that describe elemental partitioning between metal and silicate. This Bayesian technique is vastly more computationally efficient than a simple grid search and is well suited to models of planetary accretion that involve a plethora of variables. In contrast to previous work, we find that analyses of siderophile elements alone cannot yield a unique scenario for Earth's accretion. Our models predict a wide range of possible light element contents for the core, encompassing all combinations permitted by seismology and mineral physics. Specifically, we are agnostic between silicon and oxygen as the dominant light element, and the addition of carbon or sulfur is also permissible but not well constrained. Redox conditions may have remained roughly constant during Earth's accretion or relatively oxygen-rich material could have been incorporated before reduced embryos. Pressures and temperatures of equilibration, likewise, may only increase slowly throughout accretion. Therefore, we do not necessarily expect a thick (>500 km), compositionally stratified layer that is stable against convection to develop at the top of the core of Earth (or, by analogy, Venus). A thinner stable layer

Isolation and functional characterization of CE1 binding proteins.

PubMed

Lee, Sun-ji; Park, Ji Hye; Lee, Mi Hun; Yu, Ji-hyun; Kim, Soo Young

2010-12-16

Abscisic acid (ABA) is a plant hormone that controls seed germination, protective responses to various abiotic stresses and seed maturation. The ABA-dependent processes entail changes in gene expression. Numerous genes are regulated by ABA, and promoter analyses of the genes revealed that cis-elements sharing the ACGTGGC consensus sequence are ubiquitous among ABA-regulated gene promoters. The importance of the core sequence, which is generally known as ABA response element (ABRE), has been demonstrated by various experiments, and its cognate transcription factors known as ABFs/AREBs have been identified. Although necessary, ABRE alone is not sufficient, and another cis-element known as "coupling element (CE)" is required for full range ABA-regulation of gene expression. Several CEs are known. However, despite their importance, the cognate transcription factors mediating ABA response via CEs have not been reported to date. Here, we report the isolation of transcription factors that bind one of the coupling elements, CE1. To isolate CE1 binding proteins, we carried out yeast one-hybrid screens. Reporter genes containing a trimer of the CE1 element were prepared and introduced into a yeast strain. The yeast was transformed with library DNA that represents RNA isolated from ABA-treated Arabidopsis seedlings. From the screen of 3.6 million yeast transformants, we isolated 78 positive clones. Analysis of the clones revealed that a group of AP2/ERF domain proteins binds the CE1 element. We investigated their expression patterns and analyzed their overexpression lines to investigate the in vivo functions of the CE element binding factors (CEBFs). Here, we show that one of the CEBFs, AtERF13, confers ABA hypersensitivity in Arabidopsis, whereas two other CEBFs enhance sugar sensitivity. Our results indicate that a group of AP2/ERF superfamily proteins interacts with CE1. Several CEBFs are known to mediate defense or abiotic stress response, but the physiological functions

Rare earth elements in street dust and associated health risk in a municipal industrial base of central China.

PubMed

Sun, Guangyi; Li, Zhonggen; Liu, Ting; Chen, Ji; Wu, Tingting; Feng, Xinbin

2017-12-01

The content levels, distribution characteristics, and health risks associated with 15 rare earth elements (REEs) in urban street dust from an industrial city, Zhuzhou, in central China were investigated. The total REE content (∑REE) ranged from 66.1 to 237.4 mg kg -1 , with an average of 115.9 mg kg -1 , which is lower than that of Chinese background soil and Yangtze river sediment. Average content of the individual REE in street dust decreased in the order Ce > La > Nd > Y > Pr > Sm > Gd > Dy > Er > Yb > Eu > Ho > Tb > Tm > Lu. The chondrite-normalized REE pattern indicated light REE (LREE) enrichment, a relatively steep LREE trend, heavy REE (HREE) depletion, a flat HREE trend, a Eu-negative anomaly and a Ce-positive anomaly. Foremost heavy local soil and to less degree anthropogenic pollution are the main sources of REE present in street dust. Health risk associated with the exposure of REE in street dust was assessed based on the carcinogenic and non-carcinogenic effect and lifetime average daily dose. The obtained cancer and non-cancer risk values prompt for no augmented health hazard. However, children had greater health risks than that of adults.

Magnetic interactions and magnetic anisotropy in exchange coupled 4f-3d systems: a case study of a heterodinuclear Ce3+-Fe3+ cyanide-bridged complex.

PubMed

Sorace, Lorenzo; Sangregorio, Claudio; Figuerola, Albert; Benelli, Cristiano; Gatteschi, Dante

2009-01-01

We report here a detailed single-crystal EPR and magnetic study of a homologous series of complexes of the type Ln-M (Ln = La(III), Ce(III); M = Fe(III), Co(III)). We were able to obtain a detailed picture of the low-lying levels of Ce(III) and Fe(III) centres through the combined use of single-crystal EPR and magnetic susceptibility data. We show that classical ligand field theory can be of great help in rationalising the energies of the low-lying levels of both the transition-metal and rare-earth ions. The combined analysis of single-crystal EPR and magnetic data of the coupled system Ce-Fe confirmed the great complexity of the interactions involving rare-earth elements. With little uncertainty, it turned out clearly that the description of the interaction involving the lowest lying spin levels requires the introduction of the isotropic, anisotropic and antisymmetric terms.

Constraining Mantle Differentiation Processes with La-Ce and Sm-Nd Isotope Systematics

NASA Astrophysics Data System (ADS)

Willig, M.; Stracke, A.

2016-12-01

Cerium (Ce) and Neodymium (Nd) isotopic ratios in oceanic basalts reflect the time integrated La-Ce and Sm-Nd ratios, and hence the extent of light rare earth element element (LREE) depletion or enrichment of their mantle sources. New high precision Ce-Nd isotope data from several ocean islands define a tight array in ԑCe-ԑNd space with ԑNd = -8.2±0.4 ԑCe + 1.3±0.9 (S.D.), in good agreement with previous data [1, 2]. The slope of the ԑCe-ԑNd array and the overall isotopic range are sensitive indicators of the processes that govern the evolution of the mantle's LREE composition. A Monte Carlo approach is employed to simulate continuous mantle-crust differentiation by partial melting and recycling of crustal materials. Partial melting of mantle peridotites produces variably depleted mantle and oceanic crust, which evolve for different time periods, before the oceanic crust is recycled back into the mantle including small amounts of continental crust (GLOSS [3]). Subsequently, depleted mantle and recycled materials of variable age and composition melt, and the respective melts mix in different proportions. Mixing lines strongly curve towards depleted mantle, and tend to be offset from the data for increasingly older and more depleted mantle. Observed ԑCe-ԑNd in ridge [1] and ocean island basalts and the slope of the ԑCe-ԑNd array therefore define upper limits for the extent and age of LREE depletion preserved in mantle peridotites. Very old average mantle depletion ages (> ca. 1-2 Ga) for the bulk of the mantle are difficult to reconcile with the existing ԑCe-ԑNd data, consistent with the range of Nd-Hf-Os model ages in abyssal peridotites [4-6]. Moreover, unless small amounts of continental crust are included in the recycled material, it is difficult to reproduce the relatively shallow slope of the ԑCe-ԑNd array, consistent with constraints from the ԑNd - ԑHf mantle array [7]. [1] Makishima and Masuda, 1994 Chem. Geol. 118, 1-8. [2] Doucelance et al

Characteristics and genesis of Rare Earth Element (REE) in western Indonesia

NASA Astrophysics Data System (ADS)

Handoko, A. D.; Sanjaya, E.

2018-02-01

Rare Earth Element (REE) has unique properties that have been used in many hightech applications. The demand of REE increased recently in the world due to its special properties. Although REE concentration in the crust is higher than gold, economically viable deposits are still rare. Reduction of REE exports by China cause increased prices of REE. Due to this condition, exploration of potential REE mines emerged. Indonesia also participates in this phenomenon, and explore the possibility of REE mines in its area. This review will discuss the characteristics and genesis of REE and its occurrence in western Indonesia; focused in Sumatera, Tin Island, and Kalimantan. The review is done based on literature research from several resources about characteristics of rare earth element in general and in the given area. The research shows that the potential REE mines can be found in several different locations in Indonesia, such as Tin Island, Sumatera, and Kalimantan. Most of them are composed of monazite, zircon, and xenotime as rare earth minerals. Monazite iss known for its elevated number of radioactive elements, so study about radioactive content and more environment friendly ore processing becomes compulsory.

Element Abundances in Meteorites and the Earth: Implication for the Accretion of Planetary Bodies

NASA Astrophysics Data System (ADS)

Mezger, K.; Vollstaedt, H.; Maltese, A.

2017-12-01

Essentially all known inner solar system materials show near chondritic relative abundances of refractory elements and depletion in volatile elements. To a first approximation volatile element depletion correlates with the respective condensation temperature (TC) of the elements. Possible mechanisms for this depletion are incomplete condensation and partial loss by evaporation caused by heating prior to or during the planetesimal accretion. The stable isotope compositions of almost all moderately volatile elements in different meteorite classes show only minor, or no evidence for a Rayleigh-type fractionation that could be attributed to partial condensation or evaporation. The different classes of meteorites also show that the degree of depletion in their parent bodies (i.e. mostly planetesimals) is quite variable, but nevertheless systematic. For primitive and least disturbed carbonaceous chondrites the element depletion pattern is a smooth function of TC. The accessible silicate Earth also shows this general depletion pattern, but in detail it is highly complex and requires differentiation processes that are not solely controlled by TC. If only highly lithophile elements are considered the depletion pattern of the silicate Earth reveals a step function that shows that moderately volatile lithophile elements have abundances that are ca. 0.1 times the chondritic value, irrespective of their TC. This element pattern observed for bulk silicate Earth can be modelled as a mixture of two distinct components: ca. 90% of a strongly reduced planetary body that is depleted in highly volatile elements and ca. 10% of a more volatile element rich and oxidized component. This mixture can account for the apparent Pb- paradox observed in melts derived from the silicate Earth and provides a time constraint for the mixing event, which is ca. 70 My after the beginning of the solar system. This event corresponds to the giant impact that also formed the Moon.

Tipping elements in the Earth's climate system.

PubMed

Lenton, Timothy M; Held, Hermann; Kriegler, Elmar; Hall, Jim W; Lucht, Wolfgang; Rahmstorf, Stefan; Schellnhuber, Hans Joachim

2008-02-12

The term "tipping point" commonly refers to a critical threshold at which a tiny perturbation can qualitatively alter the state or development of a system. Here we introduce the term "tipping element" to describe large-scale components of the Earth system that may pass a tipping point. We critically evaluate potential policy-relevant tipping elements in the climate system under anthropogenic forcing, drawing on the pertinent literature and a recent international workshop to compile a short list, and we assess where their tipping points lie. An expert elicitation is used to help rank their sensitivity to global warming and the uncertainty about the underlying physical mechanisms. Then we explain how, in principle, early warning systems could be established to detect the proximity of some tipping points.

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

EPA Science Inventory

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

Post-magmatic solid solutions of CaCeAl2(Fe3+ 2/3□1/3)[Si2O7][SiO4]O(OH), allanite-(Ce) and REE-bearing epidote in miarolitic pegmatites of Permian Baveno granite (Verbania, central-southern alps, Italy)

NASA Astrophysics Data System (ADS)

Guastoni, Alessandro; Nestola, Fabrizio; Schiazza, Mariangela

2017-06-01

CaCeAl2(Fe3+ 2/3□1/3)[Si2O7][SiO4]O(OH), allanite-(Ce) and rare earth element (REE)-bearing epidote occur as globular aggregates and platy prismatic crystals in miarolitic cavities in a niobium, yttrium, fluorine (NYF) granitic pegmatite at Baveno, Verbania, Southern Alps, Italy. These samples were investigated by means of an electron probe micro-analyser (EPMA) and single-crystal X-ray diffraction. Our EPMA results show that the globular aggregates have the highest REE content in the core portion and decreases to REE-bearing epidote towards the rim whereas the prismatic crystals are characterized by marked oscillatory zoning that have the highest REE contents at the rim of the crystal. The unit-cell parameters of "allanites" have an intermediate unit-cell between CaCeAl2(Fe3+ 2/3□1/3)[Si2O7][SiO4]O(OH), allanite-(Ce) and REE-free epidote, because reflect the strong chemical heterogeneity of the samples which form complete solid solutions. Hydrothermal fluids control the activity and precipitation of incompatible elements like high field strength elements (HFSE), Sc and REE by hydrous F-rich fluids below the critical temperature which allow to deposit accessory minerals in the cavities with decreasing temperature. The source of REE and Y are the sheet and REE-silicates like siderophyllite-annite, and gadolinite-(Y) which underwent partial to complete decomposition by the activity of aggressive F-rich hydrothermal fluids.

Nonlinear Aeroacoustics Computations by the Space-Time CE/SE Method

NASA Technical Reports Server (NTRS)

Loh, Ching Y.

2003-01-01

The Space-Time Conservation Element and Solution Element Method, or CE/SE Method for short, is a recently developed numerical method for conservation laws. Despite its second order accuracy in space and time, it possesses low dispersion errors and low dissipation. The method is robust enough to cover a wide range of compressible flows: from weak linear acoustic waves to strong discontinuous waves (shocks). An outstanding feature of the CE/SE scheme is its truly multi-dimensional, simple but effective non-reflecting boundary condition (NRBC), which is particularly valuable for computational aeroacoustics (CAA). In nature, the method may be categorized as a finite volume method, where the conservation element (CE) is equivalent to a finite control volume (or cell) and the solution element (SE) can be understood as the cell interface. However, due to its careful treatment of the surface fluxes and geometry, it is different from the existing schemes. Currently, the CE/SE scheme has been developed to a matured stage that a 3-D unstructured CE/SE Navier-Stokes solver is already available. However, in the present review paper, as a general introduction to the CE/SE method, only the 2-D unstructured Euler CE/SE solver is chosen and sketched in section 2. Then applications of the 2-D and 3-D CE/SE schemes to linear, and in particular, nonlinear aeroacoustics are depicted in sections 3, 4, and 5 to demonstrate its robustness and capability.

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

NASA Astrophysics Data System (ADS)

Midula, Pavol; Wiche, Oliver

2016-04-01

with the other elements from this group. High amounts of As, Cd, Pb in mould horizons were proved. The surprisingly highest concentrations were determined for As (in average 3328 mg kg-1). The results of the pH measurement indicates acid conditions (in average 4.86, min. 3.89) for whole mine heap. Due to the mobility of Cd and Pb in acid environment, a high mobility of Cd in mobile soil fractions (in average 0.58 mg kg-1) was found, that seems to be responsible for the Cd pollution of Freiberger Mulde river, situated near the dump-field in the East direction from the studied area. The Pb content was in the average 1513 mg kg-1. SE analyses shows, that only the minor amounts of these metals were accounted in fractions I - IV (As: 7.75 %, Pb: 5.48 %, Cd: 26.77 %). The total Ge content in soil samples was 2.7 mg.kg-1in average. The concentrations of Nd and Ce were 17.7 mg kg-1and 38.5 mg kg-1, which is even lower than the average Nd and Ce contents in the Earth crust. However, the concentration of Ge was roughly a factor of two higher, than this average showing a large pool of Ge that could be accessed by phytoextraction. The SE analyses shows, that the average in fractions I - IV is even much lower, than in the case of the above mentioned heavy metals in comparison with Ge (1.75 %), Nd (3.28 %) and Ce (3.12 %). The BCF calculated for plants shows, that the only element, which could be possibly used as the object of phytoaccumulation is Cd (the BCF > 1) in species Populus tremula (3.0, 1.7), Spirea douglasii (1.4, 2.2) and Tanacetum vulgare (3.2, 1.3) at the most sampling places. Since these species represent the natural occurring vegetation of the dump, the use of these species together with soil amendments enhancing the plant availability of elements in soil fractions hold promise for phytoextraction of economically valuable metalloids and consequently an in situ bioremediation of the dump field. This work was realised with the support of Christin Jahns on behalf of the

MnFe2O4-graphene oxide magnetic nanoparticles as a high-performance adsorbent for rare earth elements: Synthesis, isotherms, kinetics, thermodynamics and desorption.

PubMed

Ghobadi, Misagh; Gharabaghi, Mahdi; Abdollahi, Hadi; Boroumand, Zohreh; Moradian, Marzieh

2018-06-05

In recent decades, considerable amounts of rare earth elements have been used and then released into industrial wastewater, which caused serious environmental problems. In this work, in order to recycle rare earth cations (La 3+ and Ce 3+ ) from aqueous solutions, MnFe 2 O 4 -Graphene oxide magnetic nanoparticles were synthesized and after characterization studies, their adsorption isotherms, kinetics, thermodynamics and desorption were comprehensively investigated. Characterized was performed using XRD, FE-SEM, FT-IR, Raman spectroscopy, VSM, BET and DLS. REE adsorption on MnFe 2 O 4 -GO was studied for the first time in the present work and the maximum adsorption capacity at the optimum condition (room temperature and pH = 7) for La 3+ and Ce 3+ were 1001 and 982 mg/g respectively, and the reactions were completed within 20 min. In addition, the adsorption data were well matched with the Langmuir model and the adsorption kinetics were fitted with the pseudo-second order model. The thermodynamic parameters were calculated and the reactions were found to be endothermic and spontaneous. Moreover, the Dubinin-Radushkevich model predicted chemical ion-exchange adsorption. Desorption studies also demonstrated that MnFe 2 O 4 -GO can be regenerated for multiple reuses. Overall, high adsorption capacity, chemical stability, reusability, fast kinetics, easy magnetic separation, and simple synthesis method indicated that MnFe 2 O 4 -GO is a high-performance adsorbent for REE. Copyright © 2018. Published by Elsevier B.V.

Computational Aeroacoustics by the Space-time CE/SE Method

NASA Technical Reports Server (NTRS)

Loh, Ching Y.

2001-01-01

In recent years, a new numerical methodology for conservation laws-the Space-Time Conservation Element and Solution Element Method (CE/SE), was developed by Dr. Chang of NASA Glenn Research Center and collaborators. In nature, the new method may be categorized as a finite volume method, where the conservation element (CE) is equivalent to a finite control volume (or cell) and the solution element (SE) can be understood as the cell interface. However, due to its rigorous treatment of the fluxes and geometry, it is different from the existing schemes. The CE/SE scheme features: (1) space and time treated on the same footing, the integral equations of conservation laws are solve( for with second order accuracy, (2) high resolution, low dispersion and low dissipation, (3) novel, truly multi-dimensional, simple but effective non-reflecting boundary condition, (4) effortless implementation of computation, no numerical fix or parameter choice is needed, an( (5) robust enough to cover a wide spectrum of compressible flow: from weak linear acoustic waves to strong, discontinuous waves (shocks) appropriate for linear and nonlinear aeroacoustics. Currently, the CE/SE scheme has been developed to such a stage that a 3-13 unstructured CE/SE Navier-Stokes solver is already available. However, in the present paper, as a general introduction to the CE/SE method, only the 2-D unstructured Euler CE/SE solver is chosen as a prototype and is sketched in Section 2. Then applications of the CE/SE scheme to linear, nonlinear aeroacoustics and airframe noise are depicted in Sections 3, 4, and 5 respectively to demonstrate its robustness and capability.

Mechanochemical synthesis of magnetically hard anisotropic RFe10Si2 powders with R representing combinations of Sm, Ce and Zr

NASA Astrophysics Data System (ADS)

Gabay, A. M.; Hadjipanayis, G. C.

2017-01-01

Alloy synthesis consisting of mechanical activation followed by annealing was explored as a method of manufacturing medium-grade permanent magnet materials with a reduced content of the critical rare earth elements. Four RxFe10Si2 alloys with R=Sm, Sm0.7Zr0.3, Sm0.3Ce0.3Zr0.4 and Ce0.6Zr0.4 (nominal compositions) were prepared from mixtures of Sm2O3, CeO2, ZrO2, Fe2O3 and Si powders in the presence of a reducing agent Ca and a CaO dispersant. The collected alloy particles typically consisted of few joined submicron crystals. For R=Sm, X-ray diffraction analysis reveals a significant amount of the unwanted Th2Zn17-type compound forming alongside the desired ThMn12-type 1:12 compound. A more pure 1:12 phase could be obtained for R=Ce0.6Zr0.4, but it exhibited a room-temperature coercivity of less than 1 kOe. The most pure 1:12 phase and the highest values of the coercivity (10.8 kOe) and calculated maximum energy product (13.8 MGOe) were obtained for R=Sm0.7Zr0.3 processed at 1150 °C. The calculated maximum energy products of the Sm0.3Ce0.3Zr0.4Fe10Si2 particles, with half of their rare earths constituents represented by the relatively abundant Ce, was 10.1 MGOe.

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

NASA Astrophysics Data System (ADS)

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

2018-05-01

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

Nanocrystalline Ce1- x La x O2- δ Solid Solutions Synthesized by Hydrolyzing and Oxidizing

NASA Astrophysics Data System (ADS)

Hou, Xueling; Xue, Yun; Han, Ning; Lu, Qianqian; Wang, Xiaochen; Phan, Manh-Huong; Zhong, Yunbo

2016-05-01

We undertook a novel batch production approach for the synthesis of CeO2 nanopowders doped with rare earth elements. Solid solution nanopowders of Ce1- x La x O2- δ ( x = 0.15) were successfully synthesized in a large-scale and low-cost production by hydrolyzing and oxidizing Ce-La-C alloys at room temperature and subsequent calcining of their powders at different temperatures (873-1073 K) for 1 h. The Ce-La-C alloys were prepared in a vacuum induction melting furnace. The final products were characterized by x-ray diffraction, transmission electron microscopy, Brunner-Emmet-Teller (BET) surface area analyzer, and Raman spectroscopy. The calculated lattice parameters of the cubic fluorite-type phase of CeO2 tended to increase when La3+ was incorporated into CeO2. The F 2g band shift and the absence of a peak corresponding to La2O3 in the Raman spectra consistently confirmed the incorporation of the La3+ ion into CeO2, and the formation of Ce1- x La x O2- δ solid solutions as manifested by increased oxygen vacancy defects. High-quality Ce1- x La x O2- δ nanopowders of ~10-15 nm diameter with a high BET surface area of ~77 m2 g-1 were obtained. The average crystallite size of Ce1- x La x O2- δ was found to be smaller than that of CeO2 for the same calcination temperature of 1073 K, demonstrating that the introduction of La3+ into CeO2 can stabilize the host lattice and refine the grain size at high temperatures.

Relationship between concentration of rare earth elements in soil and their distribution in plants growing near a frequented road.

PubMed

Mleczek, Patrycja; Borowiak, Klaudia; Budka, Anna; Niedzielski, Przemysław

2018-06-05

Rare earth elements (REEs) are a group of elements whose concentration in numerous environmental matrices continues to increase; therefore, the use of biological methods for their removal from soil would seem to be a safe and reasonable approach. The aim of this study was to estimate the phytoextraction efficiency and distribution of light and heavy (LREEs and HREEs) rare earth elements by three herbaceous plant species: Artemisia vulgaris L., Taraxacum officinale F.H. Wigg. and Trifolium repens L., growing at a distance of 1, 10, and 25 m from the edge of a frequented road in Poland. The concentration of REEs in soil and plants was highly correlated (r > 0.9300), which indicates the high potential of the studied plant species to phytoextraction of these elements. The largest proportion of REEs was from the group of LREEs, whereas HREEs comprised only an inconsiderable portion of the REEs group. The dominant elements in the group of LREEs were Nd and Ce, while Er was dominant in the HREEs group. Differences in the amounts of these elements influenced the total concentration of LREEs, HREEs, and finally REEs and their quantities which decreased with distance from the road. According to the Friedman rank sum test, significant differences in REEs concentration, mainly between A. vulgaris L., and T. repens L. were observed for plants growing at all three distances from the road. The same relation between A. vulgaris L. and T. officinale was observed. The efficiency of LREEs and REEs phytoextraction in the whole biomass of plants growing at all distances from the road was A. vulgaris L. > T. officinale L. > T. repens L. For HREEs, the same relationship was recorded only for plants growing at the distance 1 m from the road. Bioconcentration factor (BCF) values for LREEs and HREEs were respectively higher and lower than 1 for all studied plant species regardless of the distance from the road. The studied herbaceous plant species were able to effectively phytoextract

Rare Earth Elements in Alberta Oil Sand Process Streams

DOE PAGES

Roth, Elliot; Bank, Tracy; Howard, Bret; ...

2017-04-05

The concentrations of rare earth elements in Alberta, Canada oil sands and six oil sand waste streams were determined using inductively coupled plasma mass spectrometry (ICP–MS). The results indicate that the rare earth elements (REEs) are largely concentrated in the tailings solvent recovery unit (TSRU) sample compared to the oil sand itself. The concentration of lanthanide elements is ~1100 mg/kg (1100 ppm or 0.11 weight %), which represents a >20× increase in the concentration compared to the oil sand itself and a >7× increase compared to the North American Shale Composite (NASC). The process water, which is used to extractmore » the oil from oil sands, and the water fraction associated with the different waste streams had very low concentrations of REEs that were near or below the detection limits of the instrument, with the highest total concentration of REEs in the water fraction being less than 10 μg/L (ppb). Size and density separations were completed, and the REEs and other potentially interesting and valuable metals, such as Ti and Zr, were concentrated in different fractions. These results give insights into the possibility of recovering REEs from waste streams generated from oil sand processing.« less

Rare Earth Elements in Alberta Oil Sand Process Streams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roth, Elliot; Bank, Tracy; Howard, Bret

The concentrations of rare earth elements in Alberta, Canada oil sands and six oil sand waste streams were determined using inductively coupled plasma mass spectrometry (ICP–MS). The results indicate that the rare earth elements (REEs) are largely concentrated in the tailings solvent recovery unit (TSRU) sample compared to the oil sand itself. The concentration of lanthanide elements is ~1100 mg/kg (1100 ppm or 0.11 weight %), which represents a >20× increase in the concentration compared to the oil sand itself and a >7× increase compared to the North American Shale Composite (NASC). The process water, which is used to extractmore » the oil from oil sands, and the water fraction associated with the different waste streams had very low concentrations of REEs that were near or below the detection limits of the instrument, with the highest total concentration of REEs in the water fraction being less than 10 μg/L (ppb). Size and density separations were completed, and the REEs and other potentially interesting and valuable metals, such as Ti and Zr, were concentrated in different fractions. These results give insights into the possibility of recovering REEs from waste streams generated from oil sand processing.« less

Antimony film sensor for sensitive rare earth metal analysis in environmental samples.

PubMed

Makombe, Martin; van der Horst, Charlton; Silwana, Bongiwe; Iwuoha, Emmanuel; Somerset, Vernon

2016-07-02

A sensor for the adsorptive stripping voltammetric determination of rare earth elements has been developed. The electrochemical procedure is based on the oxidation of the rare earth elements complexed with alizarin complexone at a glassy carbon electrode that was in situ modified with an antimony film, during an anodic scan from -0.2 V to 1.1 V (vs. Ag/AgCl) and deposition potential of -0.1 V (vs. Ag/AgCl). The factors influencing the adsorptive stripping capability were optimised, including the complexing agent concentration, plating concentration of antimony and deposition time. The detection of rare earth elements (La, Ce and Pr) were realised in 0.08 M sodium acetate (pH = 5.8) solution as supporting electrolyte, with 2 × 10(-6) M alizarin complexone and 1.0 mg L(-1) antimony solution. Under the optimised conditions, a deposition time of 360 s was obtained and a linear response was observed between 1 and 25 µg L(-1). The reproducibility of the voltammetric measurements was found to be within 5.0% RSD for 12 replicate measurements of cerium(III) concentration of 5 µg L(-1) using the same electrode surface. The detection limits obtained using stripping analysis was 0.06, 0.42 and 0.71 μg L(-1) for Ce(III), La(III) and Pr(III), respectively. The developed sensor has been successfully applied for the determination of cerium, lanthanum and praseodymium in municipal tap water samples.

Rapid and highly reproducible analysis of rare earth elements by multiple collector inductively coupled plasma mass spectrometry

NASA Astrophysics Data System (ADS)

Baker, Joel; Waight, Tod; Ulfbeck, David

2002-10-01

A method has been developed for the rapid chemical separation and highly reproducible analysis of the rare earth elements (REE) by isotope dilution analysis by means of a multiple collector inductively coupled plasma mass spectrometer (MC-ICP-MS). This technique is superior in terms of the analytical reproducibility or rapidity of analysis compared with quadrupole ICP-MS or with thermal ionization mass spectrometric isotope dilution techniques. Samples are digested by standard hydrofluoric-nitric acid-based techniques and spiked with two mixed spikes. The bulk REE are separated from the sample on a cation exchange column, collecting the middle-heavy and light REE as two groups, which provides a middle-heavy REE cut with sufficient separation of the light from the heavier REE to render oxide interferences trivial, and a Ba-free light REE cut. The heavy (Er-Lu), middle (Eu-Gd), and light REE (La-Eu) concentrations are determined by three short (1 to 2 min) analyses with a CETAC Aridus desolvating nebulizer introduction system. Replicate digestions of international rock standards demonstrate that concentrations can be reproduced to <1%, which reflects weighing errors during digestion and aliquotting as inter-REE ratios reproduce to ≤0.2% (2 SD). Eu and Ce anomalies reproduce to <0.15%. In addition to determining the concentrations of polyisotopic REE by isotope dilution analysis, the concentration of monoisotopic Pr can be measured during the light REE isotope dilution run, by reference to Pr/Ce and Pr/Nd ratios measured in a REE standard solution. Pr concentrations determined in this way reproduce to <1%, and Pr/REE ratios reproduce to <0.4%. Ce anomalies calculated with La and Pr also reproduce to <0.15% (2 SD). The precise Ce (and Eu) anomaly measurements should allow greater use of these features in studying the recycling of materials with these anomalies into the mantle, or redox-induced effects on the REE during recycling and dehydration of oceanic lithosphere

A LOW-COST RARE EARTH ELEMENTS RECOVERY TECHNOLOGY - PHASE I

EPA Science Inventory

A first report of rare earth elements in northwestern Mediterranean seaweeds.

PubMed

Squadrone, Stefania; Brizio, Paola; Battuello, Marco; Nurra, Nicola; Sartor, Rocco Mussat; Benedetto, Alessandro; Pessani, Daniela; Abete, Maria Cesarina

2017-09-15

The concentrations of rare earth elements (REE) were determined by ICP-MS in dominant seaweed species, collected from three locations of the northwestern Mediterranean Sea. This is the first study to define levels and patterns of REE in macro algae from these coastal areas. Rare elements are becoming emerging inorganic contaminants in marine ecosystems, due to their worldwide increasing applications in industry, technology, medicine and agriculture. Significant inter-site and interspecies differences were registered, with higher levels of REE in brown and green macro algae than in red seaweeds. Levels of light REE were also observed to be greater compared to heavy REE in all samples. One of the investigated locations (Bergeggi, SV) had higher REE and ΣREE concentrations, probably due to its proximity to an important commercial and touristic harbor, while the other two sites were less affected by anthropogenic contaminations, and showed comparable REE patterns and lower concentrations. Rare earth elements in seaweeds. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of the Cerium Oxide (CeO2) on the Structural and Electrochemical Properties of the LaNi5Ce Metal Hydride Anode

NASA Astrophysics Data System (ADS)

Utami Hapsari, Ade; Zulfia, Anne; Raharjo, Jarot; Agustanhakri

2017-07-01

One of negative electrode, AB5-type alloy electrodes, have been extensively studied and applied in rechargeable Ni-MH batteries due to their excellent electrochemical characteristics. Some researchers have found that addition of rare earth oxides (La, Ce, Pr, Er, Tm, Yb) to AB5-type alloy (MH) electrode improves battery performance significantly. Cerium Oxide (CeO2) is a light rare earth oxide is widely obtained from the processing of tailings in mining activities. During this time, there is still little data for research applications of cerium oxide for electrode materials. In this paper, the effects of adding CeO2 on the performance metal hydride electrode were investigated. In order to study the effects of CeO2 on the performance of anode material, 1%, 2%, and 3% of weight ratio CeO2 was mixed to LaNi5 as an negative electrode. The powder mixtures were mechanically milled at a speed of rpm 240 for 2 hours using ball mill. The powder mixtures were characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). Electrochemical characteristics were measured using electrochemical impedance spectroscopy (EIS). The powder mixing showed the presence of Ce atom substitution into LaNi5 structures that affect the electrochemical properties of the material. The addition of cerium oxide at LaNi5 increase of the value of impedance. However, the addition of the value of impedance at 1% CeO2 is not significant when compared with the addition of 2% and 3% CeO2 that actually make the electrochemical properties of LaNi5 worst. Although the addition of 1% CeO2 also slightly increases the impedance value of LaNi5, but the addition of 1% CeO2 showed increase the corrosion resistance than without the addition of CeO2 and the addition of 2% and 3% CeO2.

Characterization of Rare Earth Element Minerals in Coal Utilization Byproducts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montross, Scott N.; Verba, Circe A.; Collins, Keith

The United States currently produces over 100 million tons of coal utilization byproducts (CUB) per year in the form of fly ash, bottom ash, slag, and flue gas (American Coal Ash Association (ACCA), 2015). But this “waste material” also contains potentially useful levels of rare earth elements (REE). Rare earth elements are crucial for many existing and emerging technologies, but the U.S. lacks a domestic, sustainable REE source. Our project explored the possibility of developing a supply of REEs for U.S. technologies by extracting REEs from CUBs. This work offers the potential to reduce our dependence on other countries formore » supply of these critical elements (NETL, REE 2016 Project Portfolio). Geologic and diagenetic history, industrial preparation methods, and the specific combustion process all play major roles in the composition of CUB. During combustion, inorganic mineral phases of coal particles are fluidized at temperatures higher than 1400oC, so inorganic mineral materials are oxidized, fused, disintegrated, or agglomerated into larger spherical and amorphous (non-crystalline) particles. The original mineralogy of the coal-containing rock and heating/cooling of the material significantly affects the composition and morphology of the particles in the combustion byproduct (Kutchko and Kim, 2006). Thus, different types of coal/refuse/ash must be characterized to better understand mineral evolution during the combustion process. Our research focused on developing a working model to address how REE minerals behave during the combustion process: this research should help determine the most effective engineering methods for extracting REEs from CUBs. We used multimodal imaging and image processing techniques to characterize six rock and ash samples from different coal power plants with respect to morphology, grain size, presence of mineral phases, and elemental composition. The results of these characterization activities provided thresholds for

Rare earth elements and hypertension risk among housewives: A pilot study in Shanxi Province, China.

PubMed

Wang, Bin; Yan, Lailai; Huo, Wenhua; Lu, Qun; Cheng, Zixi; Zhang, Jingxu; Li, Zhiwen

2017-01-01

Studies have shown that residents living near rare earth mining areas have high concentrations of rare earth elements (REEs) in their hair. However, the adverse effects of REEs on human health have rarely been the focus of epidemiological studies. The goal of this study was to evaluate the relationship between REEs in hair and the risk of hypertension in housewives. We recruited 398 housewives in Shanxi Province, China, consisting of 163 women with hypertension (cases) and 235 healthy women without hypertension (controls). We analyzed 15 REEs (lanthanum (La), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), Yttrium (Y), cerium (Ce), praseodymium (Pr), and neodymium (Nd)) and calcium (Ca) accumulated in housewives hair over a period of two years. The results revealed that, with the exception of Eu, concentrations of the REEs in hair were higher in the cases than in the controls. The univariate odds ratios (ORs) of the 14 REEs were >1, and four of the REEs (Dy, Tm, Yb, and Y) also had adjusted ORs > 1. The increasing dose-response trends of the four REEs further indicated the potential for increased hypertension risk. Moreover, the REEs were negatively correlated with Ca content in hair. These results might suggest an antagonistic effect of REEs on Ca in the human body. It was concluded that high intake of REEs might increase the risk of hypertension among housewives. Copyright © 2016 Elsevier Ltd. All rights reserved.

Photoeffect cross sections of some rare-earth elements at 145.4 keV

NASA Astrophysics Data System (ADS)

Umesh, T. K.; Ranganathaiah, C.; Sanjeevaiah, B.

1985-08-01

Total attenuation cross sections in the elements La, Ce, Pr, Nd, Sm, Gd, Dy, Ho, and Er were derived from the measured total cross sections of their simple oxide compounds, by employing the mixture rule at 145.4-keV photon energy. The compound cross sections have been measured by performing transmission experiments in a good geometry setup. From the derived total cross sections of elements, photoeffect cross sections have been obtained by subtracting the theoretical scattering cross sections. A good agreement is observed between the present data of photoeffect cross sections and Scofield's theoretical data.

Evolution of structural and magnetic properties in La xCe 2-xCo 16 Ti for $$0 \\leq x \\leq 2$$

DOE PAGES

Conner, Benjamin S.; McGuire, Michael A.; Veedu, Shanavas Kavungal; ...

2016-11-11

Here we examine the intrinsic magnetic and structural properties of the title alloys, permanent magnet materials based on the abundant rare-earth elements lanthanum and cerium, since these properties (T C, M sH a(K 1, K 2)) will set the upper limits on the quality of permanent magnet that can be fabricated from said alloys. Ce 2Co 16Ti has a high magnetic anisotropy (H a = 65 kOe) but a relatively low saturation magnetization (M s = 7.3 kG), and La 2Co 16Ti has a high Ms(9.5 kG) but Ha too low for most applications (16 kOe). Though these two end-membersmore » have previously well-known properties, changing economic conditions have made re-examination of systems containing cerium and lanthanum necessary as the economic viability of rare earth mining becomes dependent on extraction of products beyond what is currently considered useful and profitable within the rare earth elements. We find that replacing some lanthanum with cerium in La 2Co 16Ti increases H a by a factor of more than two, while decreasing M s by less than 5%. The measured Ms indicate maximum possible energy products in excess of 20 MG·Oe in these materials, which have Curie temperatures near 600 °C. Real energy products are expected to be greatest near x = 1. In conclusion, these findings identify La xCe 2-xCo 16Ti as a promising system for development of so-called gap magnets that fill the energy product gap between expensive rare-earth magnets and current non-rare earth alternatives.« less

Variation of Aging Precipitates and Mechanical Strength of Al-Cu-Li Alloys Caused by Small Addition of Rare Earth Elements

NASA Astrophysics Data System (ADS)

Ma, Yun-long; Li, Jin-feng

2017-09-01

The effect of small rare earth (RE) addition of 0.11%Ce, 0.2%Er and 0.082%Sc on aging precipitates and mechanical strength of an Al-(3.3-4.2)Cu-1.2Li-X alloy were investigated. It is found that Cu-rich residual particles containing RE element exist in the solutionized alloy, which leads to a decrease of dissolved Cu concentration in the solutionized matrix. Like RE-free alloy, the main aging precipitate types in RE-containing alloy are T1 (Al2CuLi) and θ' (Al2Cu), but their fraction is decreased. The strength of the corresponding alloys is therefore lowered by the small RE addition. Combined with the analysis of some reported references, it is proposed that the effect of small RE addition on Al-Cu-Li alloy strength is also associated with the Cu and Li concentrations and their ratio.

A miniature single element effusion cell for the vacuum deposition of transition-metal and rare-earth elements

NASA Astrophysics Data System (ADS)

Harris, V. G.; Koon, N. C.

1997-08-01

A miniature single element effusion cell has been fabricated and tested that allows for the high-vacuum deposition of a variety of transition-metal and rare-earth elements. The cell is designed to operate under high-vacuum conditions, ≈10-9 Torr, with low power demands, <200 W. The virtues of this evaporator are the simplicity of design and ease of fabrication, assembly, maintenance, and operation.

Distribution and source of rare earth elements in PM2.5 in Xiamen, China.

PubMed

Wang, Shanshan; Yu, Ruilian; Hu, Gongren; Hu, Qichao; Zheng, Quan

2017-12-01

Particulate matter with diameter ≤2.5 µm (PM 2.5 ) is a serious atmospheric pollutant. Composition and source analyses are essential for controlling PM 2.5 . Rare earth elements (REEs) have received little attention as a component of PM 2.5 . In the present study, PM 2.5 samples were collected in urban and suburban areas in Xiamen and analyzed for REEs. The concentration range of total REEs (∑REE) is 12.07 to 98.45 mg/kg, with a mean of 38.53 mg/kg, in urban PM 2.5 and 16.44 to 160.62 mg/kg, with a mean of 42.94 mg/kg, in suburban PM 2.5 . Light REE concentrations are higher in suburban PM 2.5 , whereas heavy REE concentrations are higher in urban PM 2.5 , implying distinct sources of REEs in urban and suburban PM 2.5 . The scatter plots of δEu-∑REE and La-Ce-Sm suggest that REEs in urban PM 2.5 originate from gasoline- and diesel-vehicle exhaust, whereas those in suburban PM 2.5 are mainly influenced by gasoline-vehicle exhaust. Environ Toxicol Chem 2017;36:3217-3222. © 2017 SETAC. © 2017 SETAC.

Bacterial Cell Surface Adsorption of Rare Earth Elements

NASA Astrophysics Data System (ADS)

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

2015-12-01

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

[Effects of rare earth compounds on human peripheral mononuclear cell telomerase and apoptosis].

PubMed

Yu, Li; Dai, Yu-Cheng; Yuan, Zhao-Kang; Li, Jie

2004-07-01

To study the effects of rare earth exposure on human telomerase and apoptosis of human peripheral mononuclear cells (PBMNs). Rare earth mine lot in Xunwu county, the biggest ion absorptive rare earth mine lot of China, was selected as the study site. Another village of Xunwu county, with comparable geological structure and social environment was selected as the control site. Thirty healthy adults were randomly selected from the study site as exposure group and another 30 healthy adults randomly selected from the control site as control group. The blood content of 15 rare earth elements, including La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y, were determined by inductive coupled plasma-source mass spectrometry (ICP-MS). The total contents of rare earth elements in the blood were calculated. The TRAP and FCM assays were carried out to analyse the telomerase and apoptosis of human PBMNCs respectively. In the exposure group, the concentration of La, Ce, Dy and Y were significantly higher (P<0.001), and Pr, Nd, Sm, Gd and Yb were higher than those in the control group (P<0.05). The total content of rare earth in the blood of exposure group showed significant difference compared with control group (P<0.001). Telomerase activity in PBMNs of the exposure group was higher than that in the control group (P<0.05); there were 11 adults in the exposure group (30 adults) and 5 adults in control group (30 adults) showed positive telomerase activity. The average age of the exposure group was (38.69 +/- 8.02) years-old, while the control group was (40.45 +/- 9.02) years-old (P >0.05). It was found that there was a significant relationship between telomerase activity and the total content of rare earth elements (P <0.01). 3. The proportion of apoptosis was not different between the two groups (P >0.05), but the cells in the S-phase and G2-M phase were increased (P <0.01) in the exposed group. The telomerase activity of PBMNs in the rare earth elements exposed group

Ce3 - xMgxCo9 : Transformation of a Pauli Paramagnet into a Strong Permanent Magnet

NASA Astrophysics Data System (ADS)

Lamichhane, Tej N.; Taufour, Valentin; Palasyuk, Andriy; Lin, Qisheng; Bud'ko, Sergey L.; Canfield, Paul C.

2018-02-01

We report on the synthesis of single-crystal and polycrystalline samples of Ce3 -xMgxCo9 solid solution (0 ≤x ≲1.4 ) and characterization of their structural and magnetic properties. The crystal structure remains rhombohedral in the whole composition range and Mg partially replaces Ce in the 6 c site of the CeCo3 structure. Ferromagnetism is induced by Mg substitutions starting as low as x =0.18 and reaching a Curie temperature as high as 450 K for x =1.35 . Measurements on single crystals with x =1.34 and TC=440 K indicate an axial magnetic anisotropy with an anisotropy field of 6 T and a magnetization of 6 μB/f .u . at 300 K. Coercicity is observed in the polycrystalline samples consistent with the observed axial magnetic anisotropy. Our discovery of ferromagnetism with large axial magnetic anisotropy induced by substituting a rare-earth element by Mg is a very promising result in the search of inexpensive permanent-magnet materials and suggests that other nonmagnetic phases, similar to CeCo3 , may also conceal nearby ferromagnetic phases.

Marine phosphorites as potential resources for heavy rare earth elements and yttrium

USGS Publications Warehouse

Hein, James; Koschinsky, Andrea; Mikesell, Mariah; Mizell, Kira; Glenn, Craig R.; Wood, Ray

2016-01-01

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.

Calcite and dolomite in intrusive carbonatites. II. Trace-element variations

NASA Astrophysics Data System (ADS)

Chakhmouradian, Anton R.; Reguir, Ekaterina P.; Couëslan, Christopher; Yang, Panseok

2016-04-01

The composition of calcite and dolomite from several carbonatite complexes (including a large set of petrographically diverse samples from the Aley complex in Canada) was studied by electron-microprobe analysis and laser-ablation inductively-coupled-plasma mass-spectrometry to identify the extent of substitution of rare-earth and other trace elements in these minerals and the effects of different igneous and postmagmatic processes on their composition. Analysis of the newly acquired and published data shows that the contents of rare-earth elements (REE) and certain REE ratios in magmatic calcite and dolomite are controlled by crystal fractionation of fluorapatite, monazite and, possibly, other minerals. Enrichment in REE observed in some samples (up to ~2000 ppm in calcite) cannot be accounted for by coupled substitutions involving Na, P or As. At Aley, the REE abundances and chondrite-normalized (La/Yb)cn ratios in carbonates decrease with progressive fractionation. Sequestration of heavy REE from carbonatitic magma by calcic garnet may be responsible for a steeply sloping "exponential" pattern and lowered Ce/Ce* ratios of calcite from Magnet Cove (USA) and other localities. Alternatively, the low levels of Ce and Mn in these samples could result from preferential removal of these elements by Ce4+- and Mn3+-bearing minerals (such as cerianite and spinels) at increasing f(O2) in the magma. The distribution of large-ion lithophile elements (LILE = Sr, Ba and Pb) in rock-forming carbonates also shows trends indicative of crystal fractionation effects (e.g., concomitant depletion in Ba + Pb at Aley, or Sr + Ba at Kerimasi), although the phases responsible for these variations cannot be identified unambiguously at present. Overall, element ratios sensitive to the redox state of the magma and its complexing characteristics (Eu/Eu*, Ce/Ce* and Y/Ho) are least variable and in both primary calcite and dolomite, approach the average chondritic values. In consanguineous

Rare Earth Elements of the Permian-Triassic Conodonts from Shelf Basin to Shallow Platform: Implications for Oceanic Redox Conditions immediately After the End-Permian Mass Extinction

NASA Astrophysics Data System (ADS)

Li, Y.; Zhao, L.; Chen, Z.; Chen, J.; Chen, Y.

2013-12-01

Rare-earth elements (REEs) can provide information regarding the influence of weathering fluxes and hydrothermal inputs on seawater chemistry as well as processes that fractionate REEs between solid and aqueous phases. Of these, cerium (Ce) distributions may provide information about variations in dissolved oxygen in seawater, and thus assess the redox conditions. The short residence times of REEs in seawater (~300-1,000 yr) can result in unique REE signatures in local watermasses. REE patterns preserved in biogenic apatite such as conodonts are ideal proxies for revealing original seawater chemistry. Here, we measured the REE content of in-situ, single albid crowns using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) in combination with an ArF (λ=193 nm) excimer laser (Lambda Physiks GeoLas 2005) and quadrupole ICP-MS (Agilent 7500a). LA-ICP-MS is ideally suited for analyzing conodonts due to its ability to measure compositional variation within single conodont elements. It has the capability to determine, with high spatial resolution, continuous compositional depth profiles through the concentric layered structure of component histologies. To evaluate paleoceanographic conditions immediately after the Permian-Triassic (P-Tr) mass extinction in various depositional settings, we sampled a nearly contemporaneous strata unit, the P-Tr boundary bed, just above the extinction horizon from six sections in South China. They represent various depositional settings from shelf basin (Chaohu and Daxiakou sections), lower part of ramp (Meishan section), normal shallow platform (Yangou section), and platform microbialite (Chongyang and Xiushui sections). The sampled unit is constrained by conodonts Hindeodus changxingensis, H. parvus, and H. staeschei Zones in Meishan. REE results obtained from conodont albid crowns show that the seawater in lower ramp and shelf basin settings contains much higher REE concentrations than that in shallow platform. Ce/Ce

Differing responses of zircon, chevkinite-(Ce), monazite-(Ce) and fergusonite-(Y) to hydrothermal alteration: Evidence from the Keivy alkaline province, Kola Peninsula, Russia

NASA Astrophysics Data System (ADS)

Macdonald, Ray; Bagiński, Bogusław; Zozulya, Dmitry

2017-09-01

A quartzolite from the Rova occurrence, Keivy alkali granite province, Kola Peninsula, Russia, is used to examine the differing responses of certain rare-metal minerals during interaction with hydrothermal fluids. The minerals are two silicates [chevkinite-(Ce) and zircon], a phosphate [monazite-(Ce)] and an oxide [fergusonite-(Y)]. Textural evidence is taken to show that the dominant alteration mechanism was interface-coupled dissolution-reprecipitation. Zircon was the most pervasively altered, possibly by broadening of cleavage planes or fractures; the other minerals were altered mainly on their rims and along cracks. The importance of cracks in promoting fluid access is stressed. The compositional effects of the alteration of each phase are documented. The hydrothermal fluids carried few ligands capable of transporting significant amounts of rare-earth elements (REE), high field strength elements (HFSE) and actinides; alteration is inferred to have been promoted by mildly alkaline, Ca-bearing fluids. Expansion cracks emanating from fergusonite-(Y) are filled with unidentified material containing up to 35 wt% UO2 and 25 wt% REE2O3, indicating late-stage, short-distance mobility of these elements. Electron microprobe chemical dating of monazite yielded an age of 1665 ± 22 Ma, much younger than the formation age of the Keivy province (2.65-2.67 Ga) but comparable to that of the Svecofennian metamorphic event which affected the area (1.9-1.7 Ga) or during fluid-thermal activation of the region during rapakivi granite magmatism (1.66-1.56 Ga). Dates for altered monazite range from 2592 ± 244 Ma to 773 ± 88 Ma and reflect disturbance of the U-Th-Pb system during alteration.

Geochemical characteristics of rare earth elements in the surface sediments from the Spratly Islands of China.

PubMed

Li, Jingxi; Sun, Chengjun; Zheng, Li; Yin, Xiaofei; Chen, Junhui; Jiang, Fenghua

2017-01-30

The geochemistry of rare earth elements (REE) in surface sediment from Cuarteron reef (N1), Johnson reef (N2), Hugh reef (N3), Gaven reef (N4), Fiery cross reef (N5), and Subi reef (N6) were firstly studied. The total REE abundance (∑REE) varied from 2.244μg·g -1 to 21.661μg·g -1 , with an average of 4.667μg·g -1 . The LREE/HREE was from 2.747 to 9.869, with an average of 3.687, which indicated that the light REE was evidently enriched. Fractionation was observed between LREE and HREE. Gd with a negative anomaly was also detected in all of the stations. The negative anomalies of δEu from 0.11 to 0.25, with an average of 0.22, and the positive anomalies of δCe from 1.38 to 3.86, with an average of 1.63. The REE individual correlation values with Ca, Mn, Mg, Sr were r Ca =-0.05, r Mn =0.26, r Mg =-0.14, and r Sr =0.08. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of the addition of low rare earth elements (lanthanum, neodymium, cerium) on the biodegradation and biocompatibility of magnesium.

PubMed

Willbold, Elmar; Gu, Xuenan; Albert, Devon; Kalla, Katharina; Bobe, Katharina; Brauneis, Maria; Janning, Carla; Nellesen, Jens; Czayka, Wolfgang; Tillmann, Wolfgang; Zheng, Yufeng; Witte, Frank

2015-01-01

Rare earth elements are promising alloying element candidates for magnesium alloys used as biodegradable devices in biomedical applications. Rare earth elements have significant effects on the high temperature strength as well as the creep resistance of alloys and they improve magnesium corrosion resistance. We focused on lanthanum, neodymium and cerium to produce magnesium alloys with commonly used rare earth element concentrations. We showed that low concentrations of rare earth elements do not promote bone growth inside a 750 μm broad area around the implant. However, increased bone growth was observed at a greater distance from the degrading alloys. Clinically and histologically, the alloys and their corrosion products caused no systematic or local cytotoxicological effects. Using microtomography and in vitro experiments, we could show that the magnesium-rare earth element alloys showed low corrosion rates, both in in vitro and in vivo. The lanthanum- and cerium-containing alloys degraded at comparable rates, whereas the neodymium-containing alloy showed the lowest corrosion rates. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Rare earth element abundances in presolar SiC

NASA Astrophysics Data System (ADS)

Ireland, T. R.; Ávila, J. N.; Lugaro, M.; Cristallo, S.; Holden, P.; Lanc, P.; Nittler, L.; Alexander, C. M. O'D.; Gyngard, F.; Amari, S.

2018-01-01

Individual isotope abundances of Ba, lanthanides of the rare earth element (REE) group, and Hf have been determined in bulk samples of fine-grained silicon carbide (SiC) from the Murchison CM2 chondrite. The analytical protocol involved secondary ion mass spectrometry with combined high mass resolution and energy filtering to exclude REE oxide isobars and Si-C-O clusters from the peaks of interest. Relative sensitivity factors were determined through analysis of NIST SRM reference glasses (610 and 612) as well as a trace-element enriched SiC ceramic. When normalised to chondrite abundances, the presolar SiC REE pattern shows significant deficits at Eu and Yb, which are the most volatile of the REE. The pattern is very similar to that observed for Group III refractory inclusions. The SiC abundances were also normalised to s-process model predictions for the envelope compositions of low-mass (1.5-3 M⊙) AGB stars with close-to-solar metallicities (Z = 0.014 and 0.02). The overall trace element abundances (excluding Eu and Yb) appear consistent with the predicted s-process patterns. The depletions of Eu and Yb suggest that these elements remained in the gas phase during the condensation of SiC. The lack of depletion in some other moderately refractory elements (like Ba), and the presence of volatile elements (e.g. Xe) indicates that these elements were incorporated into SiC by other mechanisms, most likely ion implantation.

Rare-earth abundances in chondritic meteorites

NASA Technical Reports Server (NTRS)

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

1978-01-01

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

Transport and magnetic properties of dilute rare-earth-PbSe alloys

NASA Astrophysics Data System (ADS)

Jovovic, V.; Joottu-Thiagarajan, S.; West, J.; Heremans, J. P.; Story, T.; Golacki, Z.; Paszkowicz, W.; Osinniy, V.

2007-03-01

An increase in the density of states is predicted [1] to increase the thermoelectric (TE) figure of merit, and could be induced by doping TE materials with rare-earth elements. This was attempted here: the galvanomagnetic and thermomagnetic properties of dilute alloys of PbSe and Ce, Pr, Nd, Eu, Gd and Yb were measured from 80 to 380K; magnetic susceptibilities were measured from 4 to 120K. The density of states effective mass, the relaxation time, and the carrier density and mobility are calculated from measurements of the electrical conductivity and the Hall, Seebeck and transverse Nernst-Ettingshausen coefficients. The Eu, Gd, Nd and Yb-alloyed samples are paramagnetic; the concentrations of rare-earth atoms are determined from fitting a Curie-Weiss law. The magnetic behavior of the Ce and Pr-alloyed samples is different. Ce, Pr, Nd, Gd and Yb act as donors with efficiencies that will be reported. Alloying with divalent Eu does not affect carrier density but increases the energy gap. This work suggests that the 4f orbitals preserve their atomic-like localized character and exhibit only weak sp-f hybridization. 1 G. D. Mahan and J. O. Sofo, Proc. Natl. Acad. Sci. USA 93 7436 (1996)

Volatile Element Behavior During Melting and Vaporisation on Earth and Protoplanets.

NASA Astrophysics Data System (ADS)

Wood, B. J.; Norris, C. A.

2017-12-01

During accretion the Earth and many of the smaller bodies which were added to it, underwent periods of partial melting, vaporisation and re-condensation. This resulted in patterns of volatile element depletion relative to CI chondrite which are difficult to interpret. The behavior of moderately volatile elements (Pb, Cd, Zn,Cu, In,Tl etc) during these melting, vaporisation and condensation processes is usually approximated by the temperature of condensation from a gas of solar composition. Thus, Tl and In have low condensation temperatures and are regarded as the most volatile of this group. In order to test this volatility approximation we have studied the vaporisation behavior of 13 elements (Ag,Bi,Cd,Cr,Cu,Ga,Ge,In,Pb,Sb,Sn,Tl,Zn) from molten basalt at 1 atm pressure and oxygen fugacities between Ni-NiO and 2 log units below Fe-FeO. The relative volatilities of the elements turn out to be only weakly correlated with condensation temperature, indicating that the latter is a poor proxy for volatility on molten bodies. Cu, Zn and In for example all have similar volatility in the oxygen fugacity range of concern, despite the condensation temperature of Cu (1037K at 10-4bar) being 500K greater than that of In. The oxygen fugacity dependence of volatility indicates that the volatile species are, for all elements more reduced than the melt species. We addressed the differences between condensation temperature and relative volatility in 2 steps. Firstly we used metal-silicate partitioning experiments to estimate the activity coefficients of the trace element oxides in silicate melts. We then used available thermodynamic data to compute the vapor pressures of the stable species of these 13 elements over the silicate melt at oxygen fugacities ranging from Ni-NiO to about 6 log units below Fe-FeO, which approximates the solar gas. Thus we find that presence of Cl and S in the solar gas and the stable Cl and S species of In,Tl Ga Ge Cd and Sn are important contributing

Ce 3 - x Mg x Co 9 : Transformation of a Pauli Paramagnet into a Strong Permanent Magnet

DOE PAGES

Lamichhane, Tej N.; Taufour, Valentin; Palasyuk, Andriy; ...

2018-02-23

In this article we report on the synthesis of single-crystal and polycrystalline samples of Ce 3-xMg xCo 9 solid solution (0 ≤ x ≲ 1.4) and characterization of their structural and magnetic properties. The crystal structure remains rhombohedral in the whole composition range and Mg partially replaces Ce in the 6c site of the CeCo 3 structure. Ferromagnetism is induced by Mg substitutions starting as low as x = 0.18 and reaching a Curie temperature as high as 450 K for x = 1.35 . Measurements on single crystals with x = 1.34 and T C = 440 K indicatemore » an axial magnetic anisotropy with an anisotropy field of 6 T and a magnetization of 6 μ B/f.u. at 300 K. Coercicity is observed in the polycrystalline samples consistent with the observed axial magnetic anisotropy. Our discovery of ferromagnetism with large axial magnetic anisotropy induced by substituting a rare-earth element by Mg is a very promising result in the search of inexpensive permanent-magnet materials and suggests that other nonmagnetic phases, similar to CeCo 3, may also conceal nearby ferromagnetic phases.« less

Ce 3 - x Mg x Co 9 : Transformation of a Pauli Paramagnet into a Strong Permanent Magnet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lamichhane, Tej N.; Taufour, Valentin; Palasyuk, Andriy

In this article we report on the synthesis of single-crystal and polycrystalline samples of Ce 3-xMg xCo 9 solid solution (0 ≤ x ≲ 1.4) and characterization of their structural and magnetic properties. The crystal structure remains rhombohedral in the whole composition range and Mg partially replaces Ce in the 6c site of the CeCo 3 structure. Ferromagnetism is induced by Mg substitutions starting as low as x = 0.18 and reaching a Curie temperature as high as 450 K for x = 1.35 . Measurements on single crystals with x = 1.34 and T C = 440 K indicatemore » an axial magnetic anisotropy with an anisotropy field of 6 T and a magnetization of 6 μ B/f.u. at 300 K. Coercicity is observed in the polycrystalline samples consistent with the observed axial magnetic anisotropy. Our discovery of ferromagnetism with large axial magnetic anisotropy induced by substituting a rare-earth element by Mg is a very promising result in the search of inexpensive permanent-magnet materials and suggests that other nonmagnetic phases, similar to CeCo 3, may also conceal nearby ferromagnetic phases.« less

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

PubMed

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 <0.45 microm (F(3)) and <0.2 microm (F(2)), and one truly dissolved fraction including free metal ions and inorganic and organic complexes (fractionearth 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

Rare earth element content of thermal fluids from Surprise Valley, California

DOE Data Explorer

Andrew Fowler

2015-09-23

Rare earth element measurements for thermal fluids from Surprise Valley, California. Samples were collected in acid washed HDPE bottles and acidified with concentrated trace element clean (Fisher Scientific) nitric acid. Samples were pre-concentratated by a factor of approximately 10 using chelating resin with and IDA functional group and measured on magnetic sector ICP-MS. Samples include Seyferth Hot Springs, Surprise Valley Resort Mineral Well, Leonard's Hot Spring, and Lake City Mud Volcano Boiling Spring.

Geochemical Study on an Abandoned Copper Smelting Plant Using Rare Earth Elements

NASA Astrophysics Data System (ADS)

Sun, S. H.

2017-12-01

The Shuei Nan Dong Copper Smelting Plant smelting is located on the northern coast of New Taipei City, Taiwan. The plant built in 1906 for but has been shut down since 1987. However, the watershed is continuing to discharge acid mine water into the sea; and, the acid mine drainage releases high amounts of sulfate, heavy metals without any treatment. In this study, the water samples were sequentially collected along the main channel and its tributaries in the watershed. The results of hydrochemical analysis show that the untreated inflow water can be characterized with low pH value of <3 and enriched sulfate, copper and arsenic. However, the water is much less contaminated in the upstream area until a major tributary converge. The results of principal component analysis (PCA) demonstrate that the first principal component (PC) can explain >80% of the total variance and almost all chemical components have high loadings in the PC. Therefore, the hydrochemical properties in the watershed are mainly dominated by the mixing process between main channel and the major tributary but the geochemical reactions during flow down the channel is insignificant. Rare earth elements (REE) are an excellent tracer, which can indicate sources of chemical components and geochemical reactions in water. The analysis results demonstrate two distinct REE patterns. The water with low REE can be characterized by prominent Eu positive anomaly and Ce negative anomaly, which may result from the alteration of Na-plagioclase in sandstone and oxidation reaction when contact with air, respectively. On the contrary, the water with high REE shows only minor Ce negative anomaly and insignificant Eu positive anomaly. In addition, there is an enrichment of middle REE in high-REE water, which is quite different with the REE pattern of pyrite. According to the Grawunder's study (2014), it corresponds to the complexation to sulphite during pyrite oxidation. It is worth noting that REE show no considerable

Cosmic-ray abundances of the even charge elements from Sn-50 to Ce-58 measured on HEAO-3

NASA Technical Reports Server (NTRS)

Stone, E. C.; Garrard, T. L.; Krombel, K. E.; Binns, W. R.; Israel, M. H.; Klarmann, J.; Brewster, N. R.; Fickle, R. K.; Waddington, C. J.

1983-01-01

Elements with even atomic number (Z) in the interval Z = 50-58 have been resolved in the cosmic radiation using the Heavy Nuclei Experiment on the HEAO-3 satellite. The observation that Sn-50 and Ba-56 are more abundant than Te-52 and Xe-54 indicates a substantial s-process contribution to the cosmic ray source. A significant abundance of Ce-58 provides further support for this finding.

Comparative toxicities of selected rare earth elements: Sea urchin embryogenesis and fertilization damage with redox and cytogenetic effects.

PubMed

Pagano, Giovanni; Guida, Marco; Siciliano, Antonietta; Oral, Rahime; Koçbaş, Fatma; Palumbo, Anna; Castellano, Immacolata; Migliaccio, Oriana; Thomas, Philippe J; Trifuoggi, Marco

2016-05-01

Broad-ranging adverse effects are known for rare earth elements (REE), yet only a few studies tested the toxicity of several REE, prompting studies focusing on multi-parameter REE toxicity. Trichloride salts of Y, La, Ce, Nd, Sm, Eu and Gd were tested in Paracentrotus lividus sea urchin embryos and sperm for: (1) developmental defects in either REE-exposed larvae or in the offspring of REE-exposed sperm; (2) fertilization success; (3) mitotic anomalies in REE-exposed embryos and in the offspring of REE-exposed sperm, and (4) reactive oxygen species (ROS) formation, and malondialdehyde (MDA) and nitric oxide (NO) levels. REEs affected P. lividus larvae with concentration-related increase in developmental defects, 10(-6) to 10(-4)M, ranking as: Gd(III)>Y(III)>La(III)>Nd(III)≅Eu(III)>Ce(III)≅Sm(III). Nominal concentrations of REE salts were confirmed by inductively coupled plasma mass spectrometry (ICP-MS). Significant increases in MDA levels, ROS formation, and NO levels were found in REE-exposed embryos. Sperm exposure to REEs (10(-5) to 10(-4)M) resulted in concentration-related decrease in fertilization success along with increase in offspring damage. Decreased mitotic activity and increased aberration rates were detected in REE-exposed embryos and in the offspring of REE-exposed sperm. REE-associated toxicity affecting embryogenesis, fertilization, cytogenetic and redox endpoints showed different activities of tested REEs. Damage to early life stages, along with redox and cytogenetic anomalies should be the focus of future REE toxicity studies. Copyright © 2016 Elsevier Inc. All rights reserved.

[Leaching of Rare Earth Elements from Coal Ashes Using Acidophilic Chemolithotrophic Microbial Communities].

PubMed

Muravyov, M I; Bulaev, A G; Melamud, V S; Kondrat'eva, T F

2015-01-01

A method for leaching rare earth elements from coal ash in the presence of elemental sulfur using communities of acidophilic chemolithotrophic microorganisms was proposed. The optimal parameters determined for rare element leaching in reactors were as follows: temperature, 45 degrees C; initial pH, 2.0; pulp density, 10%; and the coal ash to elemental sulfur ratio, 10 : 1. After ten days of leaching, 52.0, 52.6, and 59.5% of scandium, yttrium, and lanthanum, respectively, were recovered.

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

NASA Astrophysics Data System (ADS)

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

2016-01-01

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

Selective liquid chromatographic separation of yttrium from heavier rare earth elements using acetic acid as a novel eluent.

PubMed

Kifle, Dejene; Wibetoe, Grethe

2013-09-13

One of the major difficulties in the rare earth elements separation is purification of yttrium from heavy rare earth elements. Thus, an HPLC method using acetic acid as novel eluent was explored for selective separation of yttrium form the heavy rare earth elements. When acetic acid is used as a mobile phase yttrium eluted with the lighter lanthanides. This is contrary to its relative position amongst heavier lanthanides when eluents commonly used for separation of rare earth elements were employed. The shift in elution position of yttrium with acetic acid as eluent may reflect a relatively lower stability constant of the yttrium-AcOH complex (in the same order as for the lighter lanthanides) compared to the corresponding AcOH complexes with heavy lanthanides, enabling selective separation of yttrium from the latter. The method was successfully used for selective separation of yttrium in mixed rare earth sample containing about 80% of yttrium and about 20% of heavy rare earth oxides. Thus, the use of AcOH as eluent is an effective approach for separating and determining the trace amounts of heavy rare earth elements in large amounts of yttrium matrix. Separation was performed on C18 column by running appropriate elution programs. The effluent from the column was monitored with diode array detector at absorbance wavelength of 658nm after post column derivatization with Arsenazo III. Copyright © 2013 Elsevier B.V. All rights reserved.

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

NASA Astrophysics Data System (ADS)

Imandoust, Aidin

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

Rare earth element geochemistry characteristics of seawater and porewater from deep sea in western Pacific.

PubMed

Deng, Yinan; Ren, Jiangbo; Guo, Qingjun; Cao, Jun; Wang, Haifeng; Liu, Chenhui

2017-11-28

Deep-sea sediments contain high concentrations of rare earth element (REE) which have been regarded as a huge potential resource. Understanding the marine REE cycle is important to reveal the mechanism of REE enrichment. In order to determine the geochemistry characteristics and migration processes of REE, seawater, porewater and sediment samples were systematically collected from the western Pacific for REE analysis. The results show a relatively flat REE pattern and the HREE (Heavy REE) enrichment in surface and deep seawater respectively. The HREE enrichment distribution patterns, low concentrations of Mn and Fe and negative Ce anomaly occur in the porewater, and high Mn/Al ratios and low U concentrations were observed in sediment, indicating oxic condition. LREE (Light REE) and MREE (Middle REE) enrichment in upper layer and depletion of MREE in deeper layer were shown in porewater profile. This study suggests that porewater flux in the western Pacific basin is a minor source of REEs to seawater, and abundant REEs are enriched in sediments, which is mainly caused by the extensive oxic condition, low sedimentation rate and strong adsorption capacity of sediments. Hence, the removal of REEs of porewater may result in widespread REE-rich sediments in the western Pacific basin.

Anthropogenic gadolinium anomalies and rare earth elements in the water of Atibaia River and Anhumas Creek, Southeast Brazil.

PubMed

de Campos, Francisco Ferreira; Enzweiler, Jacinta

2016-05-01

The concentrations of rare earth elements (REE), measured in water samples from Atibaia River and its tributary Anhumas Creek, Brazil, present excess of dissolved gadolinium. Such anthropogenic anomalies of Gd in water, already described in other parts of the world, result from the use of stable and soluble Gd chelates as contrast agents in magnetic resonance imaging. Atibaia River constitutes the main water supply of Campinas Metropolitan area, and its basin receives wastewater effluents. The REE concentrations in water samples were determined in 0.22-μm pore size filtered samples, without and after preconcentration by solid-phase extraction with bis-(2-ethyl-hexyl)-phosphate. This preconcentration method was unable to retain the anthropogenic Gd quantitatively. The probable reason is that the Gd chelates dissociate slowly in acidic media to produce the free ion that is retained by the phosphate ester. Strong correlations between Gd and constituents or parameters associated with effluents confirmed the source of most Gd in water samples as anthropogenic. The shale-normalized REE patterns of Atibaia River and Anhumas Creek water samples showed light and heavy REE enrichment trends, respectively. Also, positive Ce anomalies in many Atibaia River samples, as well as the strong correlations of the REE (except Gd) with terrigenous elements, imply that inorganic colloidal particles contributed to the REE measured values.

Direct Quantification of Rare Earth Elements Concentrations in Urine of Workers Manufacturing Cerium, Lanthanum Oxide Ultrafine and Nanoparticles by a Developed and Validated ICP-MS.

PubMed

Li, Yan; Yu, Hua; Zheng, Siqian; Miao, Yang; Yin, Shi; Li, Peng; Bian, Ying

2016-03-22

Rare earth elements (REEs) have undergone a steady spread in several industrial, agriculture and medical applications. With the aim of exploring a sensitive and reliable indicator of estimating exposure level to REEs, a simple, accurate and specific ICP-MS method for simultaneous direct quantification of 15 REEs ((89)Y, (139)La, (140)Ce, (141)Pr, (146)Nd, (147)Sm, (153)Eu, (157)Gd, (159)Tb, (163)Dy, (165)Ho, (166)Er, (169)Tm, (172)Yb and (175)Lu) in human urine has been developed and validated. The method showed good linearity for all REEs in human urine in the concentrations ranging from 0.001-1.000 μg ∙ L(-1) with r² > 0.997. The limits of detection and quantification for this method were in the range of 0.009-0.010 μg ∙ L(-1) and 0.029-0.037 μg ∙ L(-1), the recoveries on spiked samples of the 15 REEs ranged from 93.3% to 103.0% and the relative percentage differences were less than 6.2% in duplicate samples, and the intra- and inter-day variations of the analysis were less than 1.28% and less than 0.85% for all REEs, respectively. The developed method was successfully applied to the determination of 15 REEs in 31 urine samples obtained from the control subjects and the workers engaged in work with manufacturing of ultrafine and nanoparticles containing cerium and lanthanum oxide. The results suggested that only the urinary levels of La (1.234 ± 0.626 μg ∙ L(-1)), Ce (1.492 ± 0.995 μg ∙ L(-1)), Nd (0.014 ± 0.009 μg ∙ L(-1)) and Gd (0.023 ± 0.010 μg ∙ L(-1)) among the exposed workers were significantly higher (p < 0.05) than the levels measured in the control subjects. From these, La and Ce were the primary components, and accounted for 88% of the total REEs. Lanthanum comprised 27% of the total REEs while Ce made up the majority of REE content at 61%. The remaining elements only made up 1% each, with the exception of Dy which was not detected. Comparison with the previously published data, the levels of urinary La and Ce in workers and

Direct Quantification of Rare Earth Elements Concentrations in Urine of Workers Manufacturing Cerium, Lanthanum Oxide Ultrafine and Nanoparticles by a Developed and Validated ICP-MS

PubMed Central

Li, Yan; Yu, Hua; Zheng, Siqian; Miao, Yang; Yin, Shi; Li, Peng; Bian, Ying

2016-01-01

Rare earth elements (REEs) have undergone a steady spread in several industrial, agriculture and medical applications. With the aim of exploring a sensitive and reliable indicator of estimating exposure level to REEs, a simple, accurate and specific ICP-MS method for simultaneous direct quantification of 15 REEs (89Y, 139La, 140Ce, 141Pr, 146Nd, 147Sm, 153Eu, 157Gd, 159Tb, 163Dy, 165Ho, 166Er, 169Tm, 172Yb and 175Lu) in human urine has been developed and validated. The method showed good linearity for all REEs in human urine in the concentrations ranging from 0.001–1.000 μg∙L−1 with r2 > 0.997. The limits of detection and quantification for this method were in the range of 0.009–0.010 μg∙L−1 and 0.029–0.037 μg∙L−1, the recoveries on spiked samples of the 15 REEs ranged from 93.3% to 103.0% and the relative percentage differences were less than 6.2% in duplicate samples, and the intra- and inter-day variations of the analysis were less than 1.28% and less than 0.85% for all REEs, respectively. The developed method was successfully applied to the determination of 15 REEs in 31 urine samples obtained from the control subjects and the workers engaged in work with manufacturing of ultrafine and nanoparticles containing cerium and lanthanum oxide. The results suggested that only the urinary levels of La (1.234 ± 0.626 μg∙L−1), Ce (1.492 ± 0.995 μg∙L−1), Nd (0.014 ± 0.009 μg∙L−1) and Gd (0.023 ± 0.010 μg∙L−1) among the exposed workers were significantly higher (p < 0.05) than the levels measured in the control subjects. From these, La and Ce were the primary components, and accounted for 88% of the total REEs. Lanthanum comprised 27% of the total REEs while Ce made up the majority of REE content at 61%. The remaining elements only made up 1% each, with the exception of Dy which was not detected. Comparison with the previously published data, the levels of urinary La and Ce in workers and the control subjects show a higher trend

Levels of major and trace elements, including rare earth elements, and ²³⁸U in Croatian tap waters.

PubMed

Fiket, Željka; Rožmarić, Martina; Krmpotić, Matea; Benedik, Ljudmila

2015-05-01

Concentrations of 46 elements, including major, trace, and rare earth elements, and (238)U in Croatian tap waters were investigated. Selected sampling locations include tap waters from various hydrogeological regions, i.e., different types of aquifers, providing insight into the range of concentrations of studied elements and (238)U activity concentrations in Croatian tap waters. Obtained concentrations were compared with the Croatian maximum contaminant levels for trace elements in water intended for human consumption, as well as WHO and EPA drinking water standards. Concentrations in all analyzed tap waters were found in accordance with Croatian regulations, except tap water from Šibenik in which manganese in concentration above maximum permissible concentration (MPC) was measured. Furthermore, in tap water from Osijek, levels of arsenic exceeded the WHO guidelines and EPA regulations. In general, investigated tap waters were found to vary considerably in concentrations of studied elements, including (238)U activity concentrations. Causes of variability were further explored using statistical methods. Composition of studied tap waters was found to be predominately influenced by hydrogeological characteristics of the aquifer, at regional and local level, the existing redox conditions, and the household plumbing system. Rare earth element data, including abundances and fractionation patterns, complemented the characterization and facilitated the interpretation of factors affecting the composition of the analyzed tap waters.

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

PubMed

Mishra, S N

2009-03-18

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

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

DOE Data Explorer

Dean Stull

2016-05-24

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

Rare-earth elements in the Permian Phosphoria Formation: Paleo proxies of ocean geochemistry

USGS Publications Warehouse

Piper, D.Z.; Perkins, R.B.; Rowe, H.D.

2007-01-01

The geochemistry of deposition of the Meade Peak Member of the Phosphoria Formation (MPM) in southeast Idaho, USA, a world-class sedimentary phosphate deposit of Permian age that extends over 300,000 km2, is ascertained from its rare earth element (REE) composition. Ratios of REE:Al2O3 suggest two sources-seawater and terrigenous debris. The seawater-derived marine fraction identifies bottom water in the Phosphoria Sea as O2-depleted, denitrifying (suboxic) most of the time, and seldom sulfate-reducing (anoxic). This interpretation is supported by earlier research that showed progressively greater ratios in the marine sediment fraction of Cr:Ni>V:Ni???Mo:Ni, relative to their ratios in seawater; for which marine Cr, V, and Mo can have a dominantly O2-depleted bottom-water source and Ni a photic-zone, largely algal, source. The water chemistry was maintained by a balance between bacterial oxidation of organic matter settling through the water column, determined largely by primary productivity in the photic zone, and the flux of oxidants into the bottom water via advection of seawater from the open ocean. Samples strongly enriched in carbonate fluorapatite, the dominant REE host mineral, have variable Er/Sm, Tm/Sm, and Yb/Sm ratios. Their distribution may represent greater advection of seawater between the Phosphoria Sea and open ocean during deposition of two ore zones than a center waste and greater upwelling of nutrient-enriched water into the photic zone. However, the mean rate of deposition of marine Ni, a trace nutrient of algae, and PO43-, a limiting nutrient, indicate that primary productivity was probably high throughout the depositional history. An alternative interpretation of the variable enrichments of Er, Tm, and Yb, relative to Sm, is that they may reflect temporally variable carbonate alkalinity of open-ocean seawater in Permian time. A more strongly negative Ce anomaly for all phosphatic units than the Ce anomaly of modern pelletal phosphate is

Rare-earth elements in the Permian Phosphoria Formation: Paleo proxies of ocean geochemistry

NASA Astrophysics Data System (ADS)

Piper, D. Z.; Perkins, R. B.; Rowe, H. D.

2007-06-01

The geochemistry of deposition of the Meade Peak Member of the Phosphoria Formation (MPM) in southeast Idaho, USA, a world-class sedimentary phosphate deposit of Permian age that extends over 300,000 km 2, is ascertained from its rare earth element (REE) composition. Ratios of REE:Al 2O 3 suggest two sources—seawater and terrigenous debris. The seawater-derived marine fraction identifies bottom water in the Phosphoria Sea as O 2-depleted, denitrifying (suboxic) most of the time, and seldom sulfate-reducing (anoxic). This interpretation is supported by earlier research that showed progressively greater ratios in the marine sediment fraction of Cr:Ni>V:Ni≫Mo:Ni, relative to their ratios in seawater; for which marine Cr, V, and Mo can have a dominantly O 2-depleted bottom-water source and Ni a photic-zone, largely algal, source. The water chemistry was maintained by a balance between bacterial oxidation of organic matter settling through the water column, determined largely by primary productivity in the photic zone, and the flux of oxidants into the bottom water via advection of seawater from the open ocean. Samples strongly enriched in carbonate fluorapatite, the dominant REE host mineral, have variable Er/Sm, Tm/Sm, and Yb/Sm ratios. Their distribution may represent greater advection of seawater between the Phosphoria Sea and open ocean during deposition of two ore zones than a center waste and greater upwelling of nutrient-enriched water into the photic zone. However, the mean rate of deposition of marine Ni, a trace nutrient of algae, and PO 43-, a limiting nutrient, indicate that primary productivity was probably high throughout the depositional history. An alternative interpretation of the variable enrichments of Er, Tm, and Yb, relative to Sm, is that they may reflect temporally variable carbonate alkalinity of open-ocean seawater in Permian time. A more strongly negative Ce anomaly for all phosphatic units than the Ce anomaly of modern pelletal phosphate

Effect of Ga addition on the valence state of Ce and magnetic properties of melt-spun Ce17Fe78-xB6Gax (x = 0-1.0) ribbons

NASA Astrophysics Data System (ADS)

Jiang, Qingzheng; Zhong, Minglong; Lei, Weikai; Zeng, Qingwen; Hu, Yongfeng; Quan, Qichen; Xu, Yaping; Hu, Xianjun; Zhang, Lili; Liu, Renhui; Ma, Shengcan; Zhong, Zhenchen

2017-08-01

The Ce17Fe78-xB6Gax (x=0-1.0) ribbons were fabricated by a melt-spinning technique in order to study the mechanism of the valence variation of Ce and their magnetic properties as well as improve the thermal stability of Ce-based rare earth permanent magnets. The systematic investigations of the Ce17Fe78-xB6Gax (x=0-1.0) alloys show that the room-temperature coercivity increases significantly from 352 kA/m at x = 0 to 492 kA/m at x = 1.0. The Curie temperature (Tc) increases monotonically from 424.5 K to 433.6 K, and the temperature coefficients of remanence (α) and coercivity (β) of the ribbons are better off from -0.56 %/K, -0.75 %/K for x = 0 to -0.45 %/K, -0.65 %/K for x = 0.75 in the temperature range of 300-400 K, respectively. The Ce L3-edge X-ray absorption near edge structure (XANES) spectrums reveal that there is more Ce4+ in ribbons under total electron yield than fluorescence yield as Ce has a high affinity with oxygen. The weight of Ce3+ increases while the weight of Ce4+ decreases in Ga-added alloys. The refined grain size and a more uniform microstructure are mainly attributed to the improved magnetic properties and thermal stability with Ga doping. This paper may serve as a reference for further developing the so-called gap magnets and the effective utilization of the rare earth resources.

Structural Responses and Finite Element Modeling of Hakka Tulou Rammed Earth Structures

NASA Astrophysics Data System (ADS)

Sranislawski, Daniel

Hakka Tulous are rammed earth structures that have survived the effects of aging and natural elements upwards of even over a thousand years. These structures have housed the Hakka people of the Fujian Province, China in natural yet modern housing that has provided benefits over newer building materials. The key building material, rammed earth, which is used for the walls of the Hakka Tulou structures, has provided structural stability along with thermal comfort to the respective inhabitants of the Hakka Tulous. Through material testing and analysis this study has examined how the Tulou structures have maintained their structural stability while also providing thermal comfort. Reports of self healing cracks in the rammed earth walls were also analyzed for their validity in this study. The study has found that although the story of the self healing crack cannot be validated, there is reason to believe that with the existence of lime, some type of autogenous healing could occur on a small scale. The study has also found, through the use of nondestructive testing, that both the internal wooden systems (flooring, roof, and column support) and the rammed earth walls, are still structurally sound. Also, rammed earth's high thermal mass along with the use of sufficient shading has allowed for a delay release of heat energy from the walls of the Tulous, thus providing thermal comfort that can be felt during both night and day temperatures. The Hakka Tulou structures have been found to resist destruction from natural disasters such as strong earthquakes even when more modern construction has not. Through finite element modeling, this study has shown that the high volume of rammed earth used in the construction of the Hakka Tulous helps dissipate lateral force energy into much lower stresses for the rammed earth wall. This absorption of lateral force energy allows the rammed earth structures to survive even the strongest of earthquakes experienced in the region. The Hakka

Fast Determination of Yttrium and Rare Earth Elements in Seawater by Inductively Coupled Plasma-Mass Spectrometry after Online Flow Injection Pretreatment.

PubMed

Zhu, Zuhao; Zheng, Airong

2018-02-23

A method for daily monitoring of yttrium and rare earth elements (YREEs) in seawater using a cheap flow injection system online coupled to inductively coupled plasma-mass spectrometry is reported. Toyopearl AF Chelate 650M ® resin permits separation and concentration of YREEs using a simple external calibration. A running cycle consumed 6 mL sample and took 5.3 min, providing a throughput of 11 samples per hour. Linear ranges were up to 200 ng kg -1 except Tm (100 ng kg -1 ). The precision of the method was <6% (RSDs, n = 5), and recoveries ranged from 93% to 106%. Limits of detection (LODs) were in the range 0.002 ng kg -1 (Tm) to 0.078 ng kg -1 (Ce). Good agreement between YREEs concentrations in CASS-4 and SLEW-3 obtained in this work and results from other studies was observed. The proposed method was applied to the determination of YREEs in seawater from the Jiulong River Estuary and the Taiwan Strait.

Rare Earth elements in individual minerals in Shergottites

NASA Technical Reports Server (NTRS)

Wadhwa, Meenakshi; Crozaz, Ghislaine

1993-01-01

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

Mineralogical controls on mobility of rare earth elements in acid mine drainage environments.

PubMed

Soyol-Erdene, T O; Valente, T; Grande, J A; de la Torre, M L

2018-08-01

Rare earth elements (REE) were analyzed in river waters, acid mine waters, and extracts of secondary precipitates collected in the Iberian Pyrite Belt. The obtained concentrations of the REE in river water and mine waters (acid mine drainage - AMD) were in the range of 0.57 μg/L (Lu) and 2579 μg/L (Ce), which is higher than previously reported in surface waters from the Iberian Pyrite Belt, but are comparable with previous findings from AMD worldwide. Total REE concentrations in river waters were ranged between 297 μg/L (Cobica River) and 7032 μg/L (Trimpancho River) with an average of 2468 μg/L. NASC (North American Shale Composite) normalized REE patterns for river and acid mine waters show clear convex curvatures in middle-REE (MREE) with respect to light- and heavy-REE. During the dissolution experiments of AMD-precipitates, heavy-REE and middle-REE generate the most enriched patterns in the solution. A small number of precipitates did not display MREE enrichment (an index Gd n /Lu n  < 1.0) in NASC normalized pattern and produced relatively lower REE concentrations in extracts. Additionally, very few samples, which mainly contained aluminum sulfates, e.g., pickeringite and alunogen, displayed light-REE enrichment relative to heavy-REE (HREE). In general, the highest retention of REE occurs in samples enriched in magnesium (epsomite or hexahydrite) and aluminum sulfates, mainly pickeringite. Copyright © 2018 Elsevier Ltd. All rights reserved.

Analysis of Rare Earth Elements in Uranium Using Handheld Laser-Induced Breakdown Spectroscopy (HH LIBS)

DOE PAGES

Manard, Benjamin T.; Wylie, E. Miller; Willson, Stephen P.

2018-05-22

In this paper, a portable handheld laser-induced breakdown spectroscopy (HH LIBS) instrument was evaluated as a rapid method to qualitatively analyze rare earth elements in a uranium oxide matrix. This research is motivated by the need for development of a method to perform rapid, at-line chemical analysis in a nuclear facility, particularly to provide a rapid first pass analysis to determine if additional actions or measurements are warranted. This will result in the minimization of handling and transport of radiological and nuclear material and subsequent exposure to their associated hazards. In this work, rare earth elements (Eu, Nd, and Yb)more » were quantitatively spiked into a uranium oxide powder and analyzed by the HH LIBS instrumentation. This method demonstrates the ability to rapidly identify elemental constituents in sub-percent levels in a uranium matrix. Preliminary limits of detection (LODs) were determined with values on the order of hundredths of a percent. Validity of this methodology was explored by employing a National Institute of Standards and Technology (NIST) standard reference materials (SRM) 610 and 612 (Trace Elements in Glass). Finally, it was determined that the HH LIBS method was able to clearly discern the rare earths elements of interest in the glass or uranium matrices.« less

Analysis of Rare Earth Elements in Uranium Using Handheld Laser-Induced Breakdown Spectroscopy (HH LIBS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manard, Benjamin T.; Wylie, E. Miller; Willson, Stephen P.

In this paper, a portable handheld laser-induced breakdown spectroscopy (HH LIBS) instrument was evaluated as a rapid method to qualitatively analyze rare earth elements in a uranium oxide matrix. This research is motivated by the need for development of a method to perform rapid, at-line chemical analysis in a nuclear facility, particularly to provide a rapid first pass analysis to determine if additional actions or measurements are warranted. This will result in the minimization of handling and transport of radiological and nuclear material and subsequent exposure to their associated hazards. In this work, rare earth elements (Eu, Nd, and Yb)more » were quantitatively spiked into a uranium oxide powder and analyzed by the HH LIBS instrumentation. This method demonstrates the ability to rapidly identify elemental constituents in sub-percent levels in a uranium matrix. Preliminary limits of detection (LODs) were determined with values on the order of hundredths of a percent. Validity of this methodology was explored by employing a National Institute of Standards and Technology (NIST) standard reference materials (SRM) 610 and 612 (Trace Elements in Glass). Finally, it was determined that the HH LIBS method was able to clearly discern the rare earths elements of interest in the glass or uranium matrices.« less

Analysis of Rare Earth Elements in Uranium Using Handheld Laser-Induced Breakdown Spectroscopy (HH LIBS).

PubMed

Manard, Benjamin T; Wylie, E Miller; Willson, Stephen P

2018-01-01

A portable handheld laser-induced breakdown spectroscopy (HH LIBS) instrument was evaluated as a rapid method to qualitatively analyze rare earth elements in a uranium oxide matrix. This research is motivated by the need for development of a method to perform rapid, at-line chemical analysis in a nuclear facility, particularly to provide a rapid first pass analysis to determine if additional actions or measurements are warranted. This will result in the minimization of handling and transport of radiological and nuclear material and subsequent exposure to their associated hazards. In this work, rare earth elements (Eu, Nd, and Yb) were quantitatively spiked into a uranium oxide powder and analyzed by the HH LIBS instrumentation. This method demonstrates the ability to rapidly identify elemental constituents in sub-percent levels in a uranium matrix. Preliminary limits of detection (LODs) were determined with values on the order of hundredths of a percent. Validity of this methodology was explored by employing a National Institute of Standards and Technology (NIST) standard reference materials (SRM) 610 and 612 (Trace Elements in Glass). It was determined that the HH LIBS method was able to clearly discern the rare earths elements of interest in the glass or uranium matrices.

Spectral analysis of rare earth elements using laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Martin, Madhavi Z.; Fox, Robert V.; Miziolek, Andrzej W.; DeLucia, Frank C.; André, Nicolas

2015-06-01

There is growing interest in rapid analysis of rare earth elements (REEs) both due to the need to find new natural sources to satisfy increased demand in their use in various electronic devices, as well as the fact that they are used to estimate actinide masses for nuclear safeguards and nonproliferation. Laser-Induced Breakdown Spectroscopy (LIBS) appears to be a particularly well-suited spectroscopy-based technology to rapidly and accurately analyze the REEs in various matrices at low concentration levels (parts-per-million). Although LIBS spectra of REEs have been reported for a number of years, further work is still necessary in order to be able to quantify the concentrations of various REEs in realworld complex samples. LIBS offers advantages over conventional solution-based radiochemistry in terms of cost, analytical turnaround, waste generation, personnel dose, and contamination risk. Rare earth elements of commercial interest are found in the following three matrix groups: 1) raw ores and unrefined materials, 2) as components in refined products such as magnets, lighting phosphors, consumer electronics (which are mostly magnets and phosphors), catalysts, batteries, etc., and 3) waste/recyclable materials (aka e-waste). LIBS spectra for REEs such as Gd, Nd, and Sm found in rare earth magnets are presented.

Spectral Analysis of Rare Earth Elements using Laser-Induced Breakdown Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, Madhavi Z; Fox, Dr. Richard V; Miziolek, Andrzej W

2015-01-01

There is growing interest in rapid analysis of rare earth elements (REEs) both due to the need to find new natural sources to satisfy increased demand in their use in various electronic devices, as well as the fact that they are used to estimate actinide masses for nuclear safeguards and nonproliferation. Laser-Induced Breakdown Spectroscopy (LIBS) appears to be a particularly well-suited spectroscopy-based technology to rapidly and accurately analyze the REEs in various matrices at low concentration levels (parts-per-million). Although LIBS spectra of REEs have been reported for a number of years, further work is still necessary in order to bemore » able to quantify the concentrations of various REEs in real-world complex samples. LIBS offers advantages over conventional solution-based radiochemistry in terms of cost, analytical turnaround, waste generation, personnel dose, and contamination risk. Rare earth elements of commercial interest are found in the following three matrix groups: 1) raw ores and unrefined materials, 2) as components in refined products such as magnets, lighting phosphors, consumer electronics (which are mostly magnets and phosphors), catalysts, batteries, etc., and 3) waste/recyclable materials (aka e-waste). LIBS spectra for REEs such as Gd, Nd, and Sm found in rare earth magnets are presented.« less

Spectral Analysis of Rare Earth Elements using Laser-Induced Breakdown Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, Madhavi Z; Fox, Dr. Richard V; Miziolek, Andrzej W

2015-01-01

There is growing interest in rapid analysis of rare earth elements (REEs) both due to the need to find new natural sources to satisfy increased demand in their use in various electronic devices, as well as the fact that they are used to estimate actinide masses for nuclear safeguards and nonproliferation. Laser-Induced Breakdown Spectroscopy (LIBS) appears to be a particularly well-suited spectroscopy-based technology to rapidly and accurately analyze the REEs in various matrices at low concentration levels (parts-per-million). Although LIBS spectra of REEs have been reported for a number of years, further work is still necessary in order to bemore » able to quantify the concentrations of various REEs in realworld complex samples. LIBS offers advantages over conventional solution-based radiochemistry in terms of cost, analytical turnaround, waste generation, personnel dose, and contamination risk. Rare earth elements of commercial interest are found in the following three matrix groups: 1) raw ores and unrefined materials, 2) as components in refined products such as magnets, lighting phosphors, consumer electronics (which are mostly magnets and phosphors), catalysts, batteries, etc., and 3) waste/recyclable materials (aka e-waste). LIBS spectra for REEs such as Gd, Nd, and Sm found in rare earth magnets are presented.« less

Spectral Analysis of Rare Earth Elements using Laser-Induced Breakdown Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Madhavi Z. Martin; Robert V. Fox; Andrzej W. Miziolek

2001-05-01

There is growing interest in rapid analysis of rare earth elements (REEs) both due to the need to find new natural sources to satisfy increased demand in their use in various electronic devices, as well as the fact that they are used to estimate actinide masses for nuclear safeguards and nonproliferation. Laser-Induced Breakdown Spectroscopy (LIBS) appears to be a particularly well-suited spectroscopy-based technology to rapidly and accurately analyze the REEs in various matrices at low concentration levels (parts-per-million). Although LIBS spectra of REEs have been reported for a number of years, further work is still necessary in order to bemore » able to quantify the concentrations of various REEs in realworld complex samples. LIBS offers advantages over conventional solution-based radiochemistry in terms of cost, analytical turnaround, waste generation, personnel dose, and contamination risk. Rare earth elements of commercial interest are found in the following three matrix groups: 1) raw ores and unrefined materials, 2) as components in refined products such as magnets, lighting phosphors, consumer electronics (which are mostly magnets and phosphors), catalysts, batteries, etc., and 3) waste/recyclable materials (aka e-waste). LIBS spectra for REEs such as Gd, Nd, and Sm found in rare earth magnets are presented.« less

Interaction of rare earth elements and components of the Horonobe deep groundwater.

PubMed

Kirishima, Akira; Kuno, Atsushi; Amamiya, Hiroshi; Kubota, Takumi; Kimuro, Shingo; Amano, Yuki; Miyakawa, Kazuya; Iwatsuki, Teruki; Mizuno, Takashi; Sasaki, Takayuki; Sato, Nobuaki

2017-02-01

To better understand the migration behavior of minor actinides in deep groundwater, the interactions between doped rare earth elements (REEs) and components of Horonobe deep groundwater were investigated. Approximately 10 ppb of the REEs, i.e. Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, and Yb were doped into a groundwater sample collected from a packed section in a borehole drilled at 140 m depth in the experiment drift of Horonobe Underground Research Laboratory in Hokkaido, Japan. The groundwater sample was sequentially filtered with a 0.2 μm pore filter, and 10 kDa, 3 kDa and 1 kDa nominal molecular weight limit (NMWL) ultrafilters with conditions kept inert. Next, the filtrate solutions were analyzed with inductively coupled plasma mass spectrometry (ICP-MS) to determine the concentrations of the REEs retained in solution at each filtration step, while the used filters were analyzed through neutron activation analysis (NAA) and TOF-SIMS element mapping to determine the amounts and chemical species of the trapped fractions of REEs on each filter. A strong relationship between the ratios of REEs retained in the filtrate solutions and the ionic radii of the associated REEs was observed; i.e. smaller REEs occur in larger proportions dissolved in the solution phase under the conditions of the Horonobe groundwater. The NAA and TOF-SIMS analyses revealed that portions of the REEs were trapped by the 0.2 μm pore filter as REE phosphates, which correspond to the species predicted to be predominant by chemical equilibrium calculations for the conditions of the Horonobe groundwater. Additionally, small portions of colloidal REEs were trapped by the 10 kDa and 3 kDa NMWL ultrafilters. These results suggest that phosphate anions play an important role in the chemical behavior of REEs in saline (seawater-based) groundwater, which may be useful for predicting the migration behavior of trivalent actinides released from radioactive waste repositories in the far

La–Ce isotope measurements by multicollector-ICPMS† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7ja00256d

PubMed Central

Münker, Carsten; Strub, Erik

2017-01-01

The 138La–138Ce decay system (half-life 1.02 × 1011 years) is a potentially highly useful tool to unravel information about the timing of geological processes and about the interaction of geological reservoirs on earth, complementing information from the more popular 147Sm–143Nd and 176Lu–176Hf isotope systems. Previously published analytical protocols were limited to TIMS. Here we present for the first time an analytical protocol that employs MC-ICPMS, with an improved precision and sensitivity. To perform sufficiently accurate La–Ce measurements, an efficient ion-chromatographic procedure is required to separate Ce from the other rare earth elements (REE) and Ba quantitatively. This study presents an improved ion-chromatographic procedure that separates La and Ce from rock samples using a three-step column separation. After REE separation by cation exchange, Ce is separated employing an Ln Spec column and selective oxidation. In the last step, a cation clean-up chemistry is performed to remove all remaining interferences. Our MC-ICPMS measurement protocol includes all stable Ce isotopes (136Ce, 138Ce, 140Ce and 142Ce), by employing a 1010 ohm amplifier for the most abundant isotope 140Ce. An external reproducibility of ±0.25ε-units (2 r.s.d) has been routinely achieved for 138Ce measurements for as little as 150–600 ng Ce, depending on the sample–skimmer cone combinations being used. Because the traditionally used JMC-304 Ce reference material is not commercially available anymore, a new reference material was prepared from AMES laboratory Ce metal (Cologne-AMES). In order to compare the new material with the previously reported isotopic composition of AMES material prepared at Mainz (Mainz-AMES), Cologne-AMES and JMC-304 were measured relative to each other in the same analytical session, demonstrating isotope heterogeneity between the two AMES and different JMC-304 batches used in the literature. To enable sufficiently precise age correction of

Scientific Objectives of China Chang E 4 CE-4 Lunar Far-side Exploration Mission

NASA Astrophysics Data System (ADS)

Zhang, Hongbo; Zeng, Xingguo; Chen, Wangli

2017-10-01

China has achieved great success in the recently CE-1~CE-3 lunar missions, and in the year of 2018, China Lunar Exploration Program (CLEP) is going to launch the CE-4 mission. CE-4 satellite is the backup satellite of CE-3, so that it also consists of a Lander and a Rover. However, CE-4 is the first mission designed to detect the far side of the Moon in human lunar exploration history. So the biggest difference between CE-4 and CE-3 is that it will be equipped with a relay satellite in Earth-Moon-L2 Point for Earth-Moon Communication. And the scientific payloads carried on the Lander and Rover will also be different. It has been announced by the Chinese government that CE-4 mission will be equipped with some new international cooperated scientific payloads, such as the Low Frequency Radio Detector from Holland, Lunar Neutron and Radiation Dose Detector from Germany, Neutral Atom Detector from Sweden, and Lunar Miniature Optical Imaging Sounder from Saudi Arabia. The main scientific objective of CE-4 is to provide scientific data for lunar far side research, including: 1)general spatial environmental study of lunar far side；2)general research on the surface, shallow layer and deep layer of lunar far side；3)detection of low frequency radio on lunar far side using Low Frequency Radio Detector, which would be the first time of using such frequency band in lunar exploration history .

Synthesis, structures and properties of two new chiral rare earth-organic frameworks constructed by L/D-tartaric acid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Gonghao; Zhang, Haitao; Miao, Hao

2015-09-15

Hydrothermal reactions of rare earth cerium with L- or D- tartaric acid afford a pair of novel chiral enantiomer coordination polymers, namely, [Ce(L-tart)(CH{sub 2}OHCH{sub 2}OH)(H{sub 2}O)]Cl (L-1) and [Ce(D-tart)(CH{sub 2}OHCH{sub 2}OH)(H{sub 2}O)]Cl (D-1). Their structures were determined by single crystal X-ray diffraction analyses and further characterized by elemental analyses, XRD, IR spectra, and TG analyses. The circular dichroism (CD) spectra and second-harmonic generation (SHG) efficiency measurements proved that they are of structural chirality in the bulk samples. To the best of our knowledge, the enantiomers of L-1 and D-1 are the first 2D chiral dilayer frameworks constructed from L/D-tartrate ligands,more » ancillary ligand ethanediol and lanthanide ion Ce. - Graphical abstract: Hydrothermal reactions of rare earth cerium with L- or D- tartaric acid afford a pair of novel chiral enantiomer coordination polymers, namely, [Ce(L-tart)(CH{sub 2}OHCH{sub 2}OH)(H{sub 2}O)]Cl (L-1) and [Ce(D-tart)(CH{sub 2}OHCH{sub 2}OH)(H{sub 2}O)]Cl (D-1). Structural analysis indicates that the enantiomers of L-1 and D-1 are the first 2D chiral dilayer frameworks constructed from L/D-tartrate ligands and ancillary ligands ethanediol reacted with lanthanide ions Ce.« less

Surface-structure-controlled sectoral zoning of the rare earth elements in fluorite from Long Lake, New York, and Bingham, New Mexico, USA

NASA Astrophysics Data System (ADS)

Bosze, Stephanie; Rakovan, John

2002-03-01

The concentration and distribution of rare earth elements (REE) in sectorally zoned fluorite crystals from Long Lake, New York, and the Hansonburg Mining District, Bingham, New Mexico, have been studied using cathodoluminescence and synchrotron X-ray fluorescence microanalysis (SXRFMA). In cubo-octahedral samples from Long Lake, New York, Ce, Nd, Gd, Dy, Ho, Er, and Tm are preferentially partitioned into the |111| sector relative to the |100| sector. Partition coefficients (K d = concentration in |111| sector/concentration in |100| sector) range between 3.5 for Ce, to 1.4 for Tm, with a general decrease in K d as elements deviated from the ionic radius of Ca 2+, for which REE substitute in fluorite. Diffusion of the REE has occurred, as evidenced by gradual changes in composition over distances of 0.2 to 0.3 mm at sector boundaries. In Bingham samples, three different partition coefficients were determined for Dy: K d|100|/|111| = 2.83, K d |100|/|110| = 1.77, and K d |110|/|111| = 1.60. These are mean K d values for a 95% confidence interval. In another sample from the same deposit, Dy, Er, and Gd were found to be preferentially incorporated into the |100| sector relative to the |210| sector with average K d |100|/|210| of 3.1, 2.4, and 2.9, respectively. In a third sample, Nd was found to be preferentially incorporated into the |110| sector relative to the |321| sector with an average K d |110|/|321| value of 2.3. Compositional heterogeneities in a given sector (concentric zoning) have been resolved using SXRFMA but are significantly less than the concentration difference across sector boundaries. Often fluorite exists in a wide variety of morphologies, as is the case in the Hansonburg Mining District of Bingham. We suggest caution when using the REE as petrogenetic indicators because fluorite trace element chemistry can vary greatly among crystals within a deposit depending on the internal morphology of a particular crystal.

Extension of CE/SE method to non-equilibrium dissociating flows

NASA Astrophysics Data System (ADS)

Wen, C. Y.; Saldivar Massimi, H.; Shen, H.

2018-03-01

In this study, the hypersonic non-equilibrium flows over rounded nose geometries are numerically investigated by a robust conservation element and solution element (CE/SE) code, which is based on hybrid meshes consisting of triangular and quadrilateral elements. The dissociating and recombination chemical reactions as well as the vibrational energy relaxation are taken into account. The stiff source terms are solved by an implicit trapezoidal method of integration. Comparison with laboratory and numerical cases are provided to demonstrate the accuracy and reliability of the present CE/SE code in simulating hypersonic non-equilibrium flows.

Identification of lanthanum-specific peptides for future recycling of rare earth elements from compact fluorescent lamps.

PubMed

Lederer, Franziska L; Curtis, Susan B; Bachmann, Stefanie; Dunbar, W Scott; MacGillivray, Ross T A

2017-05-01

As components of electronic scrap, rare earth minerals are an interesting but little used source of raw materials that are highly important for the recycling industry. Currently, there exists no cost-efficient technology to separate rare earth minerals from an electronic scrap mixture. In this study, phage surface display has been used as a key method to develop peptides with high specificity for particular inorganic targets in electronic scrap. Lanthanum phosphate doped with cerium and terbium as part of the fluorescent phosphors of spent compact fluorescent lamps (CFL) was used as a target material of economic interest to test the suitability of the phage display method to the separation of rare earth minerals. One random pVIII phage library was screened for peptide sequences that bind specifically to the fluorescent phosphor LaPO 4 :Ce 3+ ,Tb 3+ (LAP). The library contained at least 100 binding pVIII peptides per phage particle with a diversity of 1 × 10 9 different phage per library. After three rounds of enrichment, a phage clone containing the surface peptide loop RCQYPLCS was found to bind specifically to LAP. Specificity and affinity of the identified phage bound peptide was confirmed by using binding and competition assays, immunofluorescence assays, and zeta potential measurements. Binding and immunofluorescence assays identified the peptide's affinity for the fluorescent phosphor components CAT (CeMgAl 11 O 19 :Tb 3+ ) and BAM (BaMgAl 10 O 17 :Eu 2+ ). No affinity was found for other fluorescent phosphor components such as YOX (Y 2 O 3 :Eu 3+ ). The binding specificity of the RCQYPLCS peptide loop was improved 3-51-fold by using alanine scanning mutagenesis. The identification of peptides with high specificity and affinity for special components in the fluorescent phosphor in CFLs provides a potentially new strategic approach to rare earth recycling. Biotechnol. Bioeng. 2017;114: 1016-1024. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals

Enhanced phytoextraction of germanium and rare earth elements - a rhizosphere-based approach

NASA Astrophysics Data System (ADS)

Wiche, Oliver

2016-04-01

Germanium (Ge) and rare earth elements (REEs) are economically valuable raw materials that have become an integral part of our modern high tech society. While most of these elements are not actually rare in terms of general amounts in the earth's crust, they are rarely found in sufficient abundances in single locations for their mining to be economically viable. The average concentration of Ge in soils is estimated at 1.6 μg g-1. The REEs comprise a group of 16 elements including La, the group of lanthanides and Y that are abundant in the earth crust with concentrations varying from 35 μg g-1 (La), 40 μg g-1 (Nd), 6 μg g-1 (Gd) and 3.5 μg g-1 (Er) to 0.5 μg g-1 in Tm. Thus, a promising chance to improve supply of these elements could be phytomining. Unfortunately, bioavailability of Ge and REEs in soils appears to be low, in particular in neutral or alkaline soils. A sequential dissolution analysis of 120 soil samples taken from the A-horizons of soils in the area of Freiberg (Saxony, Germany) revealed that only 0.2% of total Ge and about 0.5% of La, Nd, Gd and Er of bulk concentrations were easily accessible by leaching with NH4-acetate (pH 7). Most of the investigated elements were bound to Fe-/Mn-oxides and silicates and were therefore only poorly available for plant uptake. Here we report an environmentally friendly approach for enhanced phytoextraction of Ge and REEs from soils using mixed cultures of plant species with efficient mechanisms for the acquisition of nutrients in the rhizosphere. The rhizosphere is characterized as the zone in soil sourrounding a plant root that consists of a gradient in chemical, physical and biological soil properties driven by rhizodeposits like carboxylates and protons. Some species like white lupin (Lupinus albus) are able to excrete large amounts of organic acid anions(predominantly citrate and malate) and show a particularly high potential for the acidification of the rhizosphere. In our experiments, mixed cultures

The surface sediment types and their rare earth element characteristics from the continental shelf of the northern south China sea

NASA Astrophysics Data System (ADS)

Wang, Shuhong; Zhang, Nan; Chen, Han; Li, Liang; Yan, Wen

2014-10-01

The grain size as well as some major and trace elements, including rare earth element (REE), for 273 surface sediment samples collected from the continental shelf of the northern South China Sea were analyzed in this study. The sediment types are mainly sandy silt and silt, making up 60% of the whole samples, and secondly are mud, sandy mud, muddy sand and silty sand, making up 28% of the whole samples, based on grain-size in which the Folk's classification was used. The total REE content (ΣREE) show a wide variation from 21 ppm to 244 ppm with an average value of 155 ppm, which similar to the average ΣREE of the China loess, but much different from that in deep-sea clay, showing a significant terrigenous succession. The REE contents in different sediment types vary greatly, mainly enriching in silt, sandy silt, mud and sandy mud. The REE distribution contours parallel to the coastal, presenting like strips and their contents gradually reduce with increasing distance from the coast. The high content of the western Pearl River Mouth, Shang/Xiachuan Islands and Hailing Bay might be regarded to the coastal current developed from the east to the west along to the Pearl River Mouth in the northern South China Sea. But the chondrite-normalized REE patterns in various sediment types have no difference, basically same as those of coastal rivers and upper crust. They all show relative enrichments in light rare earth element (LREE), noticeable negative Eu anomaly and no Ce anomaly, indicating that those sediments are terrigenous sediments and from the same source region. Further analysis suggest that the sedimentary environment in the study area is relatively stable and granite widely distributed in the South China mainland is the main source of REE, which are transported mainly by the Pearl River. The late diagenesis has little effect on the REE.

A novel approach for acid mine drainage pollution biomonitoring using rare earth elements bioaccumulated in the freshwater clam Corbicula fluminea.

PubMed

Bonnail, Estefanía; Pérez-López, Rafael; Sarmiento, Aguasanta M; Nieto, José Miguel; DelValls, T Ángel

2017-09-15

Lanthanide series have been used as a record of the water-rock interaction and work as a tool for identifying impacts of acid mine drainage (lixiviate residue derived from sulphide oxidation). The application of North-American Shale Composite-normalized rare earth elements patterns to these minority elements allows determining the origin of the contamination. In the current study, geochemical patterns were applied to rare earth elements bioaccumulated in the soft tissue of the freshwater clam Corbicula fluminea after exposure to different acid mine drainage contaminated environments. Results show significant bioaccumulation of rare earth elements in soft tissue of the clam after 14 days of exposure to acid mine drainage contaminated sediment (ΣREE=1.3-8μg/gdw). Furthermore, it was possible to biomonitor different degrees of contamination based on rare earth elements in tissue. The pattern of this type of contamination describes a particular curve characterized by an enrichment in the middle rare earth elements; a homologous pattern (E MREE =0.90) has also been observed when applied NASC normalization in clam tissues. Results of lanthanides found in clams were contrasted with the paucity of toxicity studies, determining risk caused by light rare earth elements in the Odiel River close to the Estuary. The current study purposes the use of clam as an innovative "bio-tool" for the biogeochemical monitoring of pollution inputs that determines the acid mine drainage networks affection. Copyright © 2017 Elsevier B.V. All rights reserved.

Rare earth elements in river waters

NASA Technical Reports Server (NTRS)

Goldstein, Steven J.; Jacobsen, Stein B.

1988-01-01

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

Atomic hydrogen in. gamma. -irradiated hydroxides of alkaline-earth elements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spitsyn, V.I.; Yurik, T.K.; Barsova, L.I.

1982-04-01

Atomic hydrogen is an important intermediate product formed in the radiolysis of compounds containing X-H bonds. H atoms have been detected in irradiated matrices of H/sub 2/ and inert gases at 4/sup 0/K, in irradiated ice and frozen solutions of acids in irradiated salts and in other systems. Here results are presented from a study of the ESR spectra of H atoms generated in polycrystalline hydroxides of alkaline-earth elements that have been ..gamma..-irradiated at 77/sup 0/K, after preliminary treatment at various temperatures. For the first time stabilization of atomic hydrogen in ..gamma..-irradiated polycrystalline alkaline-earth element hydroxides has been detected. Dependingmore » on the degree of dehydroxylation, several types of hydrogen atoms may be stabilized in the hydroxides, these hydrogen atoms having different radiospectroscopic parameters. In the magnesium-calcium-strontium-barium hydroxide series, a regular decrease has been found in the hfi constants for H atoms with the cations in the immediate surroundings. A direct proportionality has been found between the parameters ..delta..A/A/sub 0/ and the polarizability of the cation.« less

Application of stochastic approach based on Monte Carlo (MC) simulation for life cycle inventory (LCI) of the rare earth elements (REEs) in beneficiation rare earth waste from the gold processing: case study

NASA Astrophysics Data System (ADS)

Bieda, Bogusław; Grzesik, Katarzyna

2017-11-01

The study proposes an stochastic approach based on Monte Carlo (MC) simulation for life cycle assessment (LCA) method limited to life cycle inventory (LCI) study for rare earth elements (REEs) recovery from the secondary materials processes production applied to the New Krankberg Mine in Sweden. The MC method is recognizes as an important tool in science and can be considered the most effective quantification approach for uncertainties. The use of stochastic approach helps to characterize the uncertainties better than deterministic method. Uncertainty of data can be expressed through a definition of probability distribution of that data (e.g. through standard deviation or variance). The data used in this study are obtained from: (i) site-specific measured or calculated data, (ii) values based on literature, (iii) the ecoinvent process "rare earth concentrate, 70% REO, from bastnäsite, at beneficiation". Environmental emissions (e.g, particulates, uranium-238, thorium-232), energy and REE (La, Ce, Nd, Pr, Sm, Dy, Eu, Tb, Y, Sc, Yb, Lu, Tm, Y, Gd) have been inventoried. The study is based on a reference case for the year 2016. The combination of MC analysis with sensitivity analysis is the best solution for quantified the uncertainty in the LCI/LCA. The reliability of LCA results may be uncertain, to a certain degree, but this uncertainty can be noticed with the help of MC method.

RARE EARTH ELEMENT IMPACTS ON BIOLOGICAL WASTEWATER TREATMENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fujita, Y.; Barnes, J.; Fox, S.

Increasing demand for rare earth elements (REE) is expected to lead to new development and expansion in industries processing and or recycling REE. For some industrial operators, sending aqueous waste streams to a municipal wastewater treatment plant, or publicly owned treatment works (POTW), may be a cost effective disposal option. However, wastewaters that adversely affect the performance of biological wastewater treatment at the POTW will not be accepted. The objective of our research is to assess the effects of wastewaters that might be generated by new rare earth element (REE) beneficiation or recycling processes on biological wastewater treatment systems. Wemore » have been investigating the impact of yttrium and europium on the biological activity of activated sludge collected from an operating municipal wastewater treatment plant. We have also examined the effect of an organic complexant that is commonly used in REE extraction and separations; similar compounds may be a component of newly developed REE recycling processes. Our preliminary results indicate that in the presence of Eu, respiration rates for the activated sludge decrease relative to the no-Eu controls, at Eu concentrations ranging from <10 to 660 µM. Yttrium appears to inhibit respiration as well, although negative impacts have been observed only at the highest Y amendment level tested (660 µM). The organic complexant appears to have a negative impact on activated sludge activity as well, although results are variable. Ultimately the intent of this research is to help REE industries to develop environmentally friendly and economically sustainable beneficiation and recycling processes.« less

Ultra-low rare earth element content in accreted ice from sub-glacial Lake Vostok, Antarctica

NASA Astrophysics Data System (ADS)

Gabrielli, Paolo; Planchon, Frederic; Barbante, Carlo; Boutron, Claude F.; Petit, Jean Robert; Bulat, Sergey; Hong, Sungmin; Cozzi, Giulio; Cescon, Paolo

2009-10-01

This paper reports the first rare earth element (REE) concentrations in accreted ice refrozen from sub-glacial Lake Vostok (East Antarctica). REE were determined in various sections of the Vostok ice core in order to geochemically characterize its impurities. Samples were obtained from accreted ice and, for comparison, from the upper glacier ice of atmospheric origin (undisturbed, disturbed and glacial flour ice). REE concentrations ranged between 0.8-56 pg g -1 for Ce and 0.0035-0.24 pg g -1 for Lu in glacier ice, and between <0.1-24 pg g -1 for Ce and <0.0004-0.02 pg g -1 for Lu in accreted ice. Interestingly, the REE concentrations in the upper accreted ice (AC 1; characterized by visible aggregates containing a mixture of very fine terrigenous particles) and in the deeper accreted ice (AC 2; characterized by transparent ice) are lower than those in fresh water and seawater, respectively. We suggest that such ultra-low concentrations are unlikely to be representative of the real REE content in Lake Vostok, but instead may reflect phase exclusion processes occurring at the ice/water interface during refreezing. In particular, the uneven spatial distribution (on the order of a few cm) and the large range of REE concentrations observed in AC 1 are consistent with the occurrence/absence of the aggregates in adjacent ice, and point to the presence of solid-phase concentration/exclusion processes occurring within separate pockets of frazil ice during AC 1 formation. Interestingly, if the LREE enrichment found in AC 1 was not produced by chemical fractionation occurring in Lake Vostok water, this may reflect a contribution of bedrock material, possibly in combination with aeolian dust released into the lake by melting of the glacier ice. Collectively, this valuable information provides new insight into the accreted ice formation processes, the bedrock geology of East Antarctica as well as the water chemistry and circulation of Lake Vostok.

Ultra-low rare earth element content in accreted ice from sub-glacial Lake Vostok, Antarctica

NASA Astrophysics Data System (ADS)

Barbante, C.; Gabrielli, P.; Turetta, C.; Planchon, F.; Boutron, C.; Petit, J. R.; Bulat, S.; Hong, S.; Cozzi, G.; Cescon, P.

2009-12-01

We report the first rare earth element (REE) concentrations in accreted ice refrozen from sub-glacial Lake Vostok (East Antarctica). REE were determined in various sections of the Vostok ice core in order to geochemically characterize its impurities. Samples were obtained from accreted ice and, for comparison, from the upper glacier ice of atmospheric origin (undisturbed, disturbed and glacial flour ice). REE concentrations ranged between 0.8-56 pg g-1 for Ce and 0.0035- 0.24 pg g-1 for Lu in glacier ice, and between <0.1-24 pg g-1 for Ce and <0.0004-0.02 pg g-1 for Lu in accreted ice. Interestingly, the REE concentrations in the upper accreted ice (AC1;characterized by visible aggregates containing a mixture of very fine terrigenous particles) and in the deeper accreted ice (AC2; characterized by transparent ice) are lower than those in fresh water and seawater, respectively. We suggest that such ultra-low concentrations are unlikely to be representative of the real REE content in Lake Vostok, but instead may reflect phase exclusion processes occurring at the ice/water interface during refreezing. In particular, the uneven spatial distribution (on the order of a few cm) and the large range of REE concentrations observed in AC1 are consistent with the occurrence/absence of the aggregates in adjacent ice, and point to the presence of solid-phase concentration/exclusion processes occurring within separate pockets of frazil ice during AC1 formation. Interestingly, if the LREE enrichment found in AC1 was not produced by chemical fractionation occurring in Lake Vostok water, this may reflect a contribution of bedrock material, possibly in combination with aeolian dust released into the lake by melting of the glacier ice. Collectively, this valuable information provides new insight into the accreted ice formation processes, the bedrock geology of East Antarctica as well as the water chemistry and circulation of Lake Vostok.

Rare earth and trace elements of fossil vertebrate bioapatite as palaeoenvironmental and sedimentological proxies

NASA Astrophysics Data System (ADS)

Žigaitė, Živilė; Fadel, Alexandre; Pérez-Huerta, Alberto; Jeffries, Teresa

2015-04-01

Rare earth (REE) and trace element compositions of fossil vertebrate dental microremains have been studied in Silurian and Devonian vertebrate dental scales and spines in-situ, using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Samples were selected from the well-known Silurian bone beds of Vesiku and Ohesaare in Saaremaa island of Estonia, and a number of Lower Devonian localities from Spitsbergen (Svalbard), Andrée Land group. Biomineral preservation was assessed using spot semi-quantitative elemental chemistry (SEM-EDS) and electron back-scatter difractometry (EBSD) for cristallinity imaging. The obtained PAAS shale-normalised REE concentrations were evaluated using basic geochemical calculations and quantifications. The REE patterns from the Lower Devonian vertebrate apatite from Andrée Land, Spitsbergen (Wood Bay and Grey Hœk formations) did not show any recognisable taxon-specific behavior, but had rather well expressed differences of REE compositions related to biomineral structure and sedimentary settings, suggesting REE instead to reflect burial environments and sedimentological history. The Eu anomaly recorded in two of the studied localities but not in the other indicate different taphonomic conditions and palaeoenvironment, while La/Sm, La/Yb ratios sugeest considerable influence of terrestrial freshwater during the early diagenesis. The La/Yb and La/Sm plots also agree with the average REE concentrations, reflecting domination of the adsoption over substitution as principal REE uptake mechanism in the fossils which had significantly lower overall REE concentrations, and vice versa. Vesiku (Homerian, Wenlock) microremains yielded very uniform REE patterns with slightly lower overall REE concentrations in enameloid than in dentine, with strong enrichment in middle REE and depletion in heavy REE. Negative Europium (Eu) anomaly was pronounced in all the profiles, but Cerium (Ce) anomalies were not detected suggesting possible

X-ray photoelectron spectroscopy study of chemically-etched Nd-Ce-Cu-O surfaces

NASA Technical Reports Server (NTRS)

Vasquez, R. P.; Gupta, A.; Kussmaul, A.

1991-01-01

Acetic acid, Br2, and HCl solutions are investigated for removing insulating species from Nd(1.85)Ce(0.15)CuO(4-delta) (NCCO) thin film surfaces. X-ray photoelectron spectroscopy (XPS) shows that the HCl etch is most effective, yielding O 1s spectra comparable to those obtained from samples cleaned in vacuum and a clear Fermi edge in the valence band region. Reduction and oxidation reversibly induces and eliminates, respectively, Fermi level states for undoped samples, but has no clearly observable effect on the XPS spectra for doped samples. Reactivity to air is much less for NCCO compared to hole superconductors, which is attributed to the lack of reactive alkaline earth elements in NCCO.

The reactive element effect of ceria particle dispersion on alumina growth: A model based on microstructural observations

PubMed Central

Wang, X.; Peng, X.; Tan, X.; Wang, F.

2016-01-01

The oxidation kinetics of alumina-forming metals can be affected by adding a small amount of a reactive (normally rare earth) element oxide (RExOy) and the segregation of the reactive element (RE) ions to the growing alumina grain boundaries (GBs) has been considered as a responsible reason. However, this interpretation remains a controversial issue as to how RE ions are produced by RExOy which is thermodynamically and chemically stable in metals. The question is answered by a model that is based on transmission electron microscopy (TEM) investigation of a CeO2-dispersed nickel aluminide oxidized in air at 1100 °C. The CeO2 dispersion is incorporated into the alumina scale by the inward growth of inner α-Al2O3, where it partially dissolves producing tetravalent Ce cations which then transform to trivalent cations by trapping electrons. The trivalent cations segregate to the α-Al2O3 GBs and diffuse outward along first the GBs and later the twin boundaries (TBs) in the outer γ-Al2O3 layer, being precipitated as Ce2O3 particles near surface. PMID:27406938

Evaluating rare earth element availability: a case with revolutionary demand from clean technologies.

PubMed

Alonso, Elisa; Sherman, Andrew M; Wallington, Timothy J; Everson, Mark P; Field, Frank R; Roth, Richard; Kirchain, Randolph E

2012-03-20

The future availability of rare earth elements (REEs) is of concern due to monopolistic supply conditions, environmentally unsustainable mining practices, and rapid demand growth. We present an evaluation of potential future demand scenarios for REEs with a focus on the issue of comining. Many assumptions were made to simplify the analysis, but the scenarios identify some key variables that could affect future rare earth markets and market behavior. Increased use of wind energy and electric vehicles are key elements of a more sustainable future. However, since present technologies for electric vehicles and wind turbines rely heavily on dysprosium (Dy) and neodymium (Nd), in rare-earth magnets, future adoption of these technologies may result in large and disproportionate increases in the demand for these two elements. For this study, upper and lower bound usage projections for REE in these applications were developed to evaluate the state of future REE supply availability. In the absence of efficient reuse and recycling or the development of technologies which use lower amounts of Dy and Nd, following a path consistent with stabilization of atmospheric CO(2) at 450 ppm may lead to an increase of more than 700% and 2600% for Nd and Dy, respectively, over the next 25 years if the present REE needs in automotive and wind applications are representative of future needs.

Developing alternative resources of rare earth elements in Europe - EURARE and the red mud challenge

NASA Astrophysics Data System (ADS)

Deady, Eimear; Mouchos, Evangelos; Goodenough, Kathryn; Wall, Frances; Williamson, Ben

2015-04-01

Novel Untapped European Resource?" ERES 1st European Rare Earth Resources conference, Milos, Greece, (5-6/09/2014). [7] A. Wagh and W. Pinnock, "Occurrence of scandium and rare earth elements in Jamaican bauxite waste", Economic Geology, vol. 82, no. 3, pp. 757-761, May 1987. [8] G. Mongelli, "Ce-anomalies in the textural components of Upper Cretaceous karst bauxites from the Apulian carbonate platform (southern Italy)", Chemical Geology, vol. 140, no. 1, pp. 69-79, June 1997. Additional resources: www.eurare.eu; www.redmud.org.

Compositional and phase relations among rare earth element minerals

NASA Technical Reports Server (NTRS)

Burt, D. M.

1990-01-01

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

Tuning charge transfer in the LaTiO3/RO/LaNiO3 (R = rare-earth) superlattices by the rare-earth oxides interfaces from a first-principles calculation

NASA Astrophysics Data System (ADS)

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

2018-03-01

We investigate the internal charge transfer at the isopolar interfaces in LaTiO3/RO/LaNiO3 (R = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu) superlattices by means of density functional theory calculations. The charge transfer from Ti sites to Ni sites in all superlattices is induced by the electronegativity difference between the elements Ti and Ni, and the lanthanide oxides interfaces can modulate the amount of charge transfer. Comparison of the perovskite heterostructures with the different rare-earth interfaces shows that increasing the deviations of bond angles from 180.0° and the oxygen motions near the interfaces enhance charge transfer. The 4f electrons themselves of rare-earth elements have faint influences on charge transfer. In addition, the reasons why our calculated 4f states of Sm and Tm elements disagree with the experimental systems have been provided. It is hoped that all the calculated results could be used to design new functional nanoelectronic devices in perovskite oxides.

Geochemistry of some rare earth elements in groundwater, Vierlingsbeek, The Netherlands.

PubMed

Janssen, René P T; Verweij, Wilko

2003-03-01

Groundwater samples were taken from seven bore holes at depths ranging from 2 to 41m nearby drinking water pumping station Vierlingsbeek, The Netherlands and analysed for Y, La, Ce, Pr, Nd, Sm and Eu. Shale-normalized patterns were generally flat and showed that the observed rare earth elements (REE) were probably of natural origin. In the shallow groundwaters the REEs were light REE (LREE) enriched, probably caused by binding of LREEs to colloids. To improve understanding of the behaviour of the REE, two approaches were used: calculations of the speciation and a statistical approach. For the speciation calculations, complexation and precipitation reactions including inorganic and dissolved organic carbon (DOC) compounds, were taken into account. The REE speciation showed REE(3+), REE(SO(4))(+), REE(CO(3))(+) and REE(DOC) being the major species. Dissolution of pure REE precipitates and REE-enriched solid phases did not account for the observed REEs in groundwater. Regulation of REE concentrations by adsorption-desorption processes to Fe(III)(OH)(3) and Al(OH)(3) minerals, which were calculated to be present in nearly all groundwaters, is a probable explanation. The statistical approach (multiple linear regression) showed that pH is by far the most significant groundwater characteristic which contributes to the variation in REE concentrations. Also DOC, SO(4), Fe and Al contributed significantly, although to a much lesser extent, to the variation in REE concentrations. This is in line with the calculated REE-species in solution and REE-adsorption to iron and aluminium (hydr)oxides. Regression equations including only pH, were derived to predict REE concentrations in groundwater. External validation showed that these regression equations were reasonably successful to predict REE concentrations of groundwater of another drinking water pumping station in quite different region of The Netherlands.

An upwind space-time conservation element and solution element scheme for solving dusty gas flow model

NASA Astrophysics Data System (ADS)

Rehman, Asad; Ali, Ishtiaq; Qamar, Shamsul

An upwind space-time conservation element and solution element (CE/SE) scheme is extended to numerically approximate the dusty gas flow model. Unlike central CE/SE schemes, the current method uses the upwind procedure to derive the numerical fluxes through the inner boundary of conservation elements. These upwind fluxes are utilized to calculate the gradients of flow variables. For comparison and validation, the central upwind scheme is also applied to solve the same dusty gas flow model. The suggested upwind CE/SE scheme resolves the contact discontinuities more effectively and preserves the positivity of flow variables in low density flows. Several case studies are considered and the results of upwind CE/SE are compared with the solutions of central upwind scheme. The numerical results show better performance of the upwind CE/SE method as compared to the central upwind scheme.

Zircon/fluid trace element partition coefficients measured by recrystallization of Mud Tank zircon at 1.5 GPa and 800-1000 °C

NASA Astrophysics Data System (ADS)

Ayers, John C.; Peters, Timothy J.

2018-02-01

Hydrothermal zircon grains have trace element characteristics such as low Th/U, high U, and high rare earth element (REE) concentrations that distinguish them from magmatic, metamorphic, and altered zircon grains, but it is unclear whether these characteristics result from distinctive fluid compositions or zircon/fluid fractionation effects. New experiments aimed at measuring zircon/fluid trace element partition coefficients Dz/f involved recrystallizing natural Mud Tank zircon with low trace element concentrations in the presence of H2O, 1 m NaOH, or 1 m HCl doped with ∼1000 ppm of rare earth elements (REE), Y, U and Th and ∼500 ppm of Li, B, P, Nb, Ba, Hf, and Ta. Experiments were run for 168 h at 1.5 GPa, 800-1000 °C, and fO2 = NNO in a piston cylinder apparatus using the double capsule method. LA-ICP-MS analysis shows that run product zircon crystals have much higher trace element concentrations than in Mud Tank zircon starting material. Dz/f values were estimated from run product zircon analyses and bulk composition using mass balance. Most elements behave incompatibly, with median Dz/f being highest for Hf = 8 and lowest for B = 0.02. Addition of NaOH or HCl had little influence on Dz/f values. Dz/f for LREE are anomalously high, likely due to contamination of run product zircon with quenched solutes enriched in incompatible elements, so DLREE were estimated using lattice strain theory. Brice curves for +3 ions yield zircon/fluid DLu/DLa of ∼800-5000. A Brice curve fit to +4 ions yielded DCe4+ values. Estimated concentrations of Ce3+ and Ce4+ show that the average Ce4+/Ce3+ in zircon of 27 is much higher than in fluid of 0.02. Th and U show little fractionation, with median DTh/DU = 0.7, indicating that the low Th/U in natural hydrothermal zircon is inherited from the fluid. Natural fluid compositions estimated from measured Dz/f and published compositions of hydrothermal zircon grains from aplite and eclogite reflect the mineralogy of the host rock, e

Exploring the limits of EDS microanalysis: rare earth element analyses

NASA Astrophysics Data System (ADS)

Ritchie, N. W. M.; Newbury, D. E.; Lowers, H.; Mengason, M.

2018-01-01

It is a great time to be a microanalyst. After a few decades of incremental progress in energy-dispersive X-ray spectrometry (EDS), the last decade has seen the accuracy and precision surge forward. Today, the question is not whether EDS is generally useful but to identify the types of problems for which wavelength-dispersive X-ray spectrometry remains the better choice. The full extent of EDS’s capabilities has surprised many. Low Z, low energy, and trace element detection have been demonstrated even in the presence of extreme peak interferences. In this paper, we will summarise the state-of-the-art and investigate a challenging problem domain, the analysis of minerals bearing multiple rare-earth elements.

Determination of trace rare earth elements in gadolinium aluminate by inductively coupled plasma time of flight mass spectrometry

NASA Astrophysics Data System (ADS)

Saha, Abhijit; Deb, S. B.; Nagar, B. K.; Saxena, M. K.

An analytical methodology was developed for the precise quantification of ten trace rare earth elements (REEs), namely, La, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, and Tm, in gadolinium aluminate (GdAlO3) employing an ultrasonic nebulizer (USN)-desolvating device based inductively coupled plasma mass spectrometry (ICP-MS). A microwave digestion procedure was optimized for digesting 100 mg of the refractory oxide using a mixture of sulphuric acid (H2SO4), phosphoric acid (H3PO4) and water (H2O) with 1400 W power, 10 min ramp and 60 min hold time. An USN-desolvating sample introduction system was employed to enhance analyte sensitivities by minimizing their oxide ion formation in the plasma. Studies on the effect of various matrix concentrations on the analyte intensities revealed that precise quantification of the analytes was possible with matrix level of 250 mg L- 1. The possibility of using indium as an internal standard was explored and applied to correct for matrix effect and variation in analyte sensitivity under plasma operating conditions. Individual oxide ion formation yields were determined in matrix matched solution and employed for correcting polyatomic interferences of light REE (LREE) oxide ions on the intensities of middle and heavy rare earth elements (MREEs and HREEs). Recoveries of ≥ 90% were achieved for the analytes employing standard addition technique. Three real samples were analyzed for traces of REEs by the proposed method and cross validated for Eu and Nd by isotope dilution mass spectrometry (IDMS). The results show no significant difference in the values at 95% confidence level. The expanded uncertainty (coverage factor 1σ) in the determination of trace REEs in the samples were found to be between 3 and 8%. The instrument detection limits (IDLs) and the method detection limits (MDLs) for the ten REEs lie in the ranges 1-5 ng L- 1 and 7-64 μg kg- 1 respectively.

Replacing critical rare earth materials in high energy density magnets

NASA Astrophysics Data System (ADS)

McCallum, R. William

2012-02-01

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

Enrichment of rare earth metal ions by the highly selective adsorption of phytate intercalated layered double hydroxide.

PubMed

Jin, Cheng; Liu, Huimin; Kong, Xianggui; Yan, Hong; Lei, Xiaodong

2018-02-27

Phytate intercalated MgAl layered double hydroxide (MgAl-LDH) was prepared by an anion exchange method with the precursor NO 3 - containing MgAl-LDH. The final as-synthesized product [Mg 0.69 Al 0.31 (OH) 2 ] (phytateNa 6 ) 0.05 (NO 3 ) 0.01 ·mH 2 O (phytate-LDH) has highly selective adsorption ability for some metal ions and can be used to enrich rare earth metal ions in mixed solution, such as Pr 3+ and Ce 3+ from a mixed solution of them with Pb 2+ and Co 2+ . At first, phytate-LDH has good adsorption performance for these ions in single metal ion solutions. At low concentration (below 10 mg L -1 ), all the capture rates of the four metal ions were more than 97%, for highly toxic Pb 2+ it was even up to nearly 100%, and a high capture rate (99.87%) was maintained for Pb 2+ at a high concentration (100 mg L -1 ). When all the four metal ions are co-existing in aqueous solution, the selectivity order is Pb 2+ ≫ Pr 3+ ≈ Ce 3+ > Co 2+ . In a solution containing mixtures of the three metal ions of Pr 3+ , Ce 3+ , and Co 2+ , the selectivity order is Pr 3+ ≈ Ce 3+ ≫ Co 2+ , and in a solution containing mixtures of Pr 3+ with Co 2+ and Ce 3+ with Co 2+ , the selectivity orders are Pr 3+ ≫ Co 2+ and Ce 3+ ≫ Co 2+ , respectively. The high selectivity and adsorption capacities for Pb 2+ , Co 2+ , Pr 3+ , and Ce 3+ result in the efficient removal of Pb 2+ and enrichment of the rare earth metal ions Pr 3+ and Ce 3+ by phytate-LDH. Based on the elemental analysis, it is found that the difference of the adsorption capacities is mainly due to the different coordination number of them with phytate-LDH. With molecular simulation, we believe that the adsorption selectivity is due to the difference of the binding energy between the metal ion and phytate-LDH. Therefore, the phytate-LDH is promising for the enrichment and/or purification of the rare earth metal ions and removal of toxic metal ions from waste water.

Experimental geochemistry of Pu and Sm and the thermodynamics of trace element partitioning

NASA Technical Reports Server (NTRS)

Jones, John H.; Burnett, Donald S.

1987-01-01

An experimental study of the partitioning of Pu and Sm between diopside/liquid and whitlockite/liquid supports the hypothesis that Pu behaves as a light rare earth element during igneous processes in reducing environments. D-Pu/D-Sm is found to be about 2 for both diopsidic pyroxene and whitlockite, and the amount of fractionation would be decreased further if Pu were compared to Ce or Nd. Data indicate that temperature, rather than melt composition, is the most important control on elemental partitioning, and that P2O5 in aluminosilicate melts serves as a complexing agent for the actinides and lanthanides.

Microwave-assisted Extraction of Rare Earth Elements from Petroleum Refining Catalysts and Ambient Fine Aerosols Prior to Inductively Coupled Plasma - Mass Spectrometry

NASA Technical Reports Server (NTRS)

Mittlefehldt, David W.; Kulkarni, Pranav; Chellam, Shankar

2006-01-01

In the absence of a certified reference material, a robust microwave-assisted acid digestion procedure followed by inductively coupled plasma - mass spectrometry (ICP-MS) was developed to quantify rare earth elements (REEs) in fluidized-bed catalytic cracking (FCC) catalysts and atmospheric fine particulate matter (PM2.5). High temperature (200 C), high pressure (200 psig), acid digestion (HNO3, HF, and H3BO3) with 20 minute dwell time effectively solubilized REEs from six fresh catalysts, a spent catalyst, and PM2.5. This method was also employed to measure 27 non-REEs including Na, Mg, Al, Si, K, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Zr, Mo, Cd, Cs, Ba, Pb, and U. Complete extraction of several REEs (Y, La, Ce, Pr, Nd, Tb, Dy, and Er) required HF indicating that they were closely associated with the aluminosilicate structure of the zeolite FCC catalysts. Internal standardization using 115In quantitatively corrected non-spectral interferences in the catalyst digestate matrix. Inter-laboratory comparison using ICP-optical emission spectroscopy (ICP-OES) and instrumental neutron activation analysis (INAA) demonstrated the applicability of the newly developed analytical method for accurate analysis of REEs in FCC catalysts. The method developed for FCC catalysts was also successfully implemented to measure trace to ultra-trace concentrations of La, Ce, Pr, Nd, Sm, Gd, Eu, and Dy in ambient PM2.5 in an industrial area of Houston, TX.

Chemical speciation and bioavailability of rare earth elements (REEs) in the ecosystem: a review.

PubMed

Khan, Aysha Masood; Bakar, Nor Kartini Abu; Bakar, Ahmad Farid Abu; Ashraf, Muhammad Aqeel

2017-10-01

Rare earths (RE), chemically uniform group of elements due to similar physicochemical behavior, are termed as lanthanides. Natural occurrence depends on the geological circumstances and has been of long interest for geologist as tools for further scientific research into the region of ores, rocks, and oceanic water. The review paper mainly focuses to provide scientific literature about rare earth elements (REEs) with potential environmental and health effects in understanding the research. This is the initial review of RE speciation and bioavailability with current initiative toward development needs and research perceptive. In this paper, we have also discussed mineralogy, extraction, geochemistry, analytical methods of rare earth elements. In this study, REEs with their transformation and vertical distribution in different environments such as fresh and seawater, sediments, soil, weathering, transport, and solubility have been reported with most recent literature along key methods of findings. Speciation and bioavailability have been discussed in detail with special emphasis on soil, plant, and aquatic ecosystems and their impacts on the environment. This review shows that REE gained more importance in last few years due to their detrimental effects on living organisms, so their speciation, bioavailability, and composition are much more important to evaluate their health risks and are discussed thoroughly as well.

Rare-earth elements

USGS Publications Warehouse

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

Energy Resolution and Temperature Dependence of Ce:GAGG Coupled to 3mm × 3mm Silicon Photomultipliers

NASA Astrophysics Data System (ADS)

Seitz, B.; Rivera, N. Campos; Stewart, A. G.

2016-04-01

Scintillators are a critical component of sensor systems for the detection of ionizing radiation. Such systems have a diverse portfolio of applications from medical imaging, well logging in oil exploration, and detection systems for the prevention of the illicit movement of nuclear materials. The rare earth element cerium is an ideal dopant for a variety of host scintillating materials due to the fast 5d1 → 4f radiative transition of Ce3+. Cerium-doped gadolinium aluminium gallium garnet (Ce:GAGG) is a relatively new single crystal scintillator with several interesting properties. These include high light yield, an emission peak well-matched to silicon sensors, and low intrinsic energy resolution. Moreover, the material has high density and is nonhygroscopic. In this paper, we review the properties of cerium-doped GAGG and report energy-resolution (ER) measurements over the temperature range -10°C to +50°C for 3 × 3 × 30 mm3 Ce:GAGG crystals optically coupled to a silicon photomultipler (SiPM) sensor with a 3 mm × 3 mm active area. In addition, the linearity of the scintillator-SiPM response as a function of gamma energy is reported.

Picosecond absorption spectroscopy of self-trapped excitons and transient Ce states in LaBr3 and LaBr3:Ce

NASA Astrophysics Data System (ADS)

Li, Peiyun; Gridin, Sergii; Ucer, K. Burak; Williams, Richard T.; Menge, Peter R.

2018-04-01

Picosecond time-resolved optical absorption spectra induced by two-photon interband excitation of LaBr3 are reported. The spectra are similar in general characteristics to self-trapped exciton (STE) absorption previously measured in alkali halides and alkaline-earth halides. A broad ultraviolet absorption band results from excitation of the self-trapped hole within the STE. A series of infrared and red-visible bands results from excitation of the bound outer electron within the STE similar to bands found in alkali halides corresponding to different degrees of "off-center" relaxation. Induced absorption in cerium-doped LaBr3 after band-gap excitation of the host exhibits similar STE spectra, except it decays faster on the tens-of-picoseconds scale in proportion to the Ce concentration. This is attributed to dipole-dipole energy transfer from STE to Ce3 + dopant ions. The absorption spectra were also measured after direct excitation of the Ce3 + ions with sufficient intensity to drive two- and three-photon resonantly enhanced excitation. In this case, the spectrum attributed to STEs created adjacent to Ce3 + ions decays in 1 ps suggesting dipole-dipole transfer from the nearest-neighbor separation. A transient absorption band at 2.1 eV growing with Ce concentration is found and attributed to a charge-transfer excitation of the Ce3 +* excited state responsible for scintillation in LaBr3:Ce crystals. This study concludes that the energy transport from host to activator responsible for the scintillation of LaBr3:Ce proceeds by STE creation and dipole-dipole transfer more than by sequential trapping of holes and electrons on Ce3 + ions.

Geochemical behaviour of dissolved trace elements in a monsoon-dominated tropical river basin, Southwestern India.

PubMed

Gurumurthy, G P; Balakrishna, K; Tripti, M; Audry, Stéphane; Riotte, Jean; Braun, J J; Udaya Shankar, H N

2014-04-01

The study presents a 3-year time series data on dissolved trace elements and rare earth elements (REEs) in a monsoon-dominated river basin, the Nethravati River in tropical Southwestern India. The river basin lies on the metamorphic transition boundary which separates the Peninsular Gneiss and Southern Granulitic province belonging to Archean and Tertiary-Quaternary period (Western Dharwar Craton). The basin lithology is mainly composed of granite gneiss, charnockite and metasediment. This study highlights the importance of time series data for better estimation of metal fluxes and to understand the geochemical behaviour of metals in a river basin. The dissolved trace elements show seasonality in the river water metal concentrations forming two distinct groups of metals. First group is composed of heavy metals and minor elements that show higher concentrations during dry season and lesser concentrations during the monsoon season. Second group is composed of metals belonging to lanthanides and actinides with higher concentration in the monsoon and lower concentrations during the dry season. Although the metal concentration of both the groups appears to be controlled by the discharge, there are important biogeochemical processes affecting their concentration. This includes redox reactions (for Fe, Mn, As, Mo, Ba and Ce) and pH-mediated adsorption/desorption reactions (for Ni, Co, Cr, Cu and REEs). The abundance of Fe and Mn oxyhydroxides as a result of redox processes could be driving the geochemical redistribution of metals in the river water. There is a Ce anomaly (Ce/Ce*) at different time periods, both negative and positive, in case of dissolved phase, whereas there is positive anomaly in the particulate and bed sediments. The Ce anomaly correlates with the variations in the dissolved oxygen indicating the redistribution of Ce between particulate and dissolved phase under acidic to neutral pH and lower concentrations of dissolved organic carbon. Unlike other

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

USDA-ARS?s Scientific Manuscript database

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

A volatile topic: Parsing out the details of Earth's formation through experimental metal-silicate partitioning of volatile and moderately volatile elements

NASA Astrophysics Data System (ADS)

Mahan, B. M.; Siebert, J.; Blanchard, I.; Badro, J.; Sossi, P.; Moynier, F.

2017-12-01

Volatile and moderately volatile elements display different volatilities and siderophilities, as well as varying sensitivity to thermodynamic controls (X, P, T, fO2) during metal-silicate differentiation. The experimental determination of the metal-silicate partitioning of these elements permits us to evaluate processes controlling the distribution of these elements in Earth. In this work, we have combined metal-silicate partitioning data and results for S, Sn, Zn and Cu, and input these characterizations into Earth formation models. Model parameters such as source material, timing of volatile delivery, fO2 path, and degree of impactor equilibration were varied to encompass an array of possible formation scenarios. These models were then assessed to discern plausible sets of conditions that can produce current observed element-to-element ratios (e.g. S/Zn) in the Earth's present-day mantle, while also satisfying current estimates on the S content of the core, at no more than 2 wt%. The results of our models indicate two modes of accretion that can maintain chondritic element-to-element ratios for the bulk Earth and can arrive at present-day mantle abundances of these elements. The first mode requires the late addition of Earth's entire inventory of these elements (assuming a CI-chondritic composition) and late-stage accretion that is marked by partial equilibration of large impactors. The second, possibly more intuitive mode, requires that Earth accreted - at least initially - from volatile poor material preferentially depleted in S relative to Sn, Zn, and Cu. From a chemical standpoint, this source material is most similar to type I chondrule rich (and S poor) materials (Hewins and Herzberg, 1996; Mahan et al., 2017; Amsellem et al., 2017), such as the metal-bearing carbonaceous chondrites.

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

NASA Astrophysics Data System (ADS)

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.

Tipping elements in the Earth's climate system

PubMed Central

Lenton, Timothy M.; Held, Hermann; Kriegler, Elmar; Hall, Jim W.; Lucht, Wolfgang; Rahmstorf, Stefan; Schellnhuber, Hans Joachim

2008-01-01

The term “tipping point” commonly refers to a critical threshold at which a tiny perturbation can qualitatively alter the state or development of a system. Here we introduce the term “tipping element” to describe large-scale components of the Earth system that may pass a tipping point. We critically evaluate potential policy-relevant tipping elements in the climate system under anthropogenic forcing, drawing on the pertinent literature and a recent international workshop to compile a short list, and we assess where their tipping points lie. An expert elicitation is used to help rank their sensitivity to global warming and the uncertainty about the underlying physical mechanisms. Then we explain how, in principle, early warning systems could be established to detect the proximity of some tipping points. PMID:18258748

Comparative studies on the concentration of rare earth elements and heavy metals in the atmospheric particulate matter in Beijing, China, and in Delft, The Netherlands.

PubMed

Wang, C X; Zhu, W; Peng, A; Guichreit, R

2001-05-01

Atmospheric particulate matter (APM) was collected at three sampling sites in Beijing, China, from February to June 1998. The concentrations of rare earth elements (REE) and cobalt (Co), zinc (Zn), copper (Cu), cadmium (Cd) and lead (Pb) in the APM were determined by inductively coupled plasma mass spectrometry (ICP-MS). The results obtained in Beijing, China, were compared to that obtained in Delft, the Netherlands, in 1997. The influence of coal combustion was considered. The results demonstrated that the content of APM, the concentrations of REE and Co, Zn, Cd, Pb in the APM in Beijing, China, were higher than that in Delft, the Netherlands. From the ratios of La to Ce, and La to Sm, which may be used as tracers for the origin of the REE, it is concluded that the origins of REE in China differ from those in the Netherlands.

Sustainability of rare earth elements chain: from production to food - a review.

PubMed

Turra, Christian

2018-02-01

Rare earth elements (REE) are a group of chemical elements that include lanthanoids (lanthanum to lutetium), scandium and yttrium. In the last decades, the REE demand in the industry and other areas has increased significantly. In general, REE have shown low concentrations in soils, plants, water and atmosphere, but they may accumulate in such environments due to anthropogenic inputs. In areas where there is REE contamination, the slow accumulation of these elements in the environment could become problematic. Many studies have shown environmental areas contaminated with REE and their toxic effects. Thus, it is important to review, in order to improve the current understanding of these elements in the environment, showing the effects of REE exposure in mining, soil, water, plants and food. Besides, there are few suppliers and a limited quantity of these elements in the world. This paper suggests options to improve the sustainability management of REE chain.

The Earth Based Ground Stations Element of the Lunar Program

NASA Technical Reports Server (NTRS)

Gal-Edd, Jonathan; Fatig, Curtis; Schier, James; Lee, Charles

2007-01-01

The Lunar Architecture Team (LAT) is responsible for developing a concept for building and supporting a lunar outpost with several exploration capabilities such as rovers, colonization, and observatories. The lunar outpost is planned to be located at the Moon's South Pole. The LAT Communications and Navigation Team (C&N) is responsible for defining the network infrastructure to support the lunar outpost. The following elements are needed to support lunar outpost activities: A Lunar surface network based on industry standard wireless 802.xx protocols, relay satellites positioned 180 degrees apart to provide South Pole coverage for the half of the lunar 28-day orbit that is obscured from Earth view, earth-based ground stations deployed at geographical locations 120 degrees apart. This paper will focus on the Earth ground stations of the lunar architecture. Two types of ground station networks are discussed. One provides Direct to Earth (DTE) support to lunar users using Kaband 23/26Giga-Hertz (GHz) communication frequencies. The second supports the Lunar Relay Satellite (LRS) that will be using Ka-band 40/37GHz (Q-band). This paper will discuss strategies to provide a robust operational network in support of various lunar missions and trades of building new antennas at non-NASA facilities, to improve coverage and provide site diversification for handling rain attenuation.

Aeroacoustics Computation for Nearly Fully Expanded Supersonic Jets Using the CE/SE Method

NASA Technical Reports Server (NTRS)

Loh, Ching Y.; Hultgren, Lennart S.; Wang, Xiao Y.; Chang, Sin-Chung; Jorgenson, Philip C. E.

2000-01-01

In this paper, the space-time conservation element solution element (CE/SE) method is tested in the classical axisymmetric jet instability problem, rendering good agreement with the linear theory. The CE/SE method is then applied to numerical simulations of several nearly fully expanded axisymmetric jet flows and their noise fields and qualitative agreement with available experimental and theoretical results is demonstrated.

A pilot study on the association between rare earth elements in maternal hair and the risk of neural tube defects in north China.

PubMed

Huo, Wenhua; Zhu, Yibing; Li, Zhenjiang; Pang, Yiming; Wang, Bin; Li, Zhiwen

2017-07-01

Rare earth elements (REEs) have many applications in industry, agriculture, and medicine, resulting in occupational and environmental exposure and concerns regarding REE-associated health effects. However, few epidemiological studies have examined the adverse effects of REEs on pregnancy outcomes. Therefore, this study examined the relationship between the REE concentrations in maternal hair growing during early pregnancy and the risk of neural tube defects (NTDs) in offspring. We included 191 women with NTD-affected pregnancies (cases) and 261 women delivering healthy infants (controls). The cases were divided into three subtypes: anencephaly, spina bifida, and encephalocele. Four REEs in maternal hair were analyzed by inductively coupled plasma-mass spectrometry: lanthanum (La), cerium (Ce), praseodymium (Pr), and neodymium (Nd). A questionnaire was used to collect information about maternal sociodemographic characteristics and dietary habits. The median concentrations of Ce and Pr in the NTD group were higher than those in the control group, whereas there were no significant differences for La and Nd. The adjusted odds ratios (ORs) for the four REE concentrations above the median in the case groups were not significantly > 1. An increasing frequency of the consumption of beans or bean products and fresh fruit was negatively correlated with the four REE concentrations. Our results did not suggest that the concentrations of REEs in maternal hair were associated with the risk of NTDs or any subtype of NTDs in the general population. Copyright © 2017 Elsevier Ltd. All rights reserved.

Further considerations of the Ce/Yb vs. Ba/Ce plot in volcanology and tectonics

USGS Publications Warehouse

Doe, B.R.

2002-01-01

and in Ba/Ce (>8) relative to the OIV field. There are some exceptions, also, for IAV that plot outside the IAV field. The values of Ce/Yb in Mariana Islands samples, for example, are exceptionally low for the IAV (Ce/Yb <5 with many samples <2). Examples of two cross-chain Kasuga Islands, however, have average, values of Ce/Yb considerably greater than for any other Mariana Islands data, and individual samples extend from within the IAV field into the OIV field, which may indicate a mixture of IAV and OIV sources (rather than involvement of a hotspot, these island volcanics have been interpreted as magma of OIV entrapped "plums" in an IAV "pudding" by Stern et al., 1993). Not Surprisingly, continental are volcanics, (CAV) are generally similar to IAV, but with somewhat greater dispersion in Ce/Yb, perhaps representing a larger contribution of continental materials to the volcanics. Continental rift volcanics (CRV) are complex. The Antarctic rift data fall in the OIV field, and clearly define a hotspot origin for the rift with little contamination in the continental lithosphere, but most CRV data fall in the IAV field (Rio Grande rift tholeiites, Yellowstone Plateau basalts, Columbia River basalts. East African rift hasalts). The Yellowstone basalt samples judged to be least crustally contaminated from other considerations (e.g., through Pb and Sr isotopes) approach closest to the OIV or hotspot field in the Ce/Yb vs. Ba/Ce plot, compatible with a hotspot origin with variable continental lithosphere interactions. The data from the Rio Grande rift have no such trend in Ce/Yb vs. Ba/Ce. Other trace element and isotopic data are suggestive of a different kind of origin, perhaps melting in the continental lithosphere from pressure release or other causes as suggested in the literature. Carbonatites, kimberlites, and ultrap

Phase equilibrium relations in the binary systems LiPO 3CeP 3O 9 and NaPO 3CeP 3O 9

NASA Astrophysics Data System (ADS)

Rzaigui, Mohamed; Ariguib, Najia Kbir

1981-10-01

The LiPO 3CeP 3O 9 and NaPO 3CeP 3O 9 systems have been investigated for the first time by DTA, X-ray diffraction, and infrared spectroscopy. Each system forms a single 1:1 compound. LiCe(PO 3) 4 melts in a peritectic reaction at 980°C. NaCe(PO 3) 4 melts incongruently, too, at 865°C. These compounds have a monoclinic unit cell with the parameters: a = 16.415(6), b = 7,042(6), c = 9.772(7)Å; β = 126.03(5)°; Z = 4; space group {C 2}/{c} for LiCe (PO 3) 4; and a = 9.981(4), b = 13.129(6), c = 7.226(5) Å, β = 89.93(4)°, Z = 4, space group {P2 1}/{n} for NaCe(PO 3) 4. It is established that both compounds are mixed polyphosphates with chain structure of the type | MIIMIIIII (PO 3) 4| ∞MII: alkali metal, MIIIII: rare earth.

Self-interaction-corrected local-spin-density calculations for rare earth materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Svane, A.; Temmerman, W.M.; Szotek, Z.

2000-04-20

The ab initio self-interaction-corrected (SIC) local-spin-density (LSD) approximation is discussed with emphasis on the ability to describe localized f-electron states in rare earth solids. Two methods for minimizing the SIC-LSD total energy functional are discussed, one using a unified Hamiltonian for all electron states, thus having the advantages of Bloch's theorem, the other one employing an iterative scheme in real space. Results for cerium and cerium compounds as well as other rare earths are presented. For the cerium compounds the onset of f-electron delocalization can be accurately described, including the intricate isostructural phase transitions in elemental cerium and CeP. Inmore » Pr and Sm the equilibrium lattice constant and zero temperature equation of state is greatly improved in comparison with the LSD results.« less

Synthesis, extraction and electronic structure of Ce@C2n

NASA Astrophysics Data System (ADS)

Liu, Bing-Bing; Zou, Guang-Tian; Yang, Hai-Bin; Yu, San; Lu, Jin-Shan; Liu, Zi-Yang; Liu, Shu-Ying; Xu, Wen-Guo

1997-11-01

In view of the growing interest in endohedral lanthanide fullerenes, Ce, as a typical+ 4 oxidation state lanthanide element, has been systematically studied. The synthesis, extraction and electronic structure of Ce @ C2n are investigated. Soot containing Ce@C2n was synthesized in high yield by carbonizing CeO2-containing graphite rods and are back-burning the CeC2-enriched cathode deposit in a DC arc plasma apparatus. Ce@C2n dominated by Ce@C82, can be efficiently extracted from the insoluble part of the soot after toluene Soxhlet extraction by pyridine at high temperature and high pressure in a closed vessel. About 60% Ce@C2n(2n = 82, 80, 78, 76) and 35% Ce@C82 can be enriched in the pyridine extract. This fact is identified by desorption electron impact mass spectrometry (DEI MS). The electronic structure of Ce@C2n is analyzed by using X-ray photoemission spectroscopy (XPS) of pyridine-free film. It is suggested that the encapsulated Ce atom is in a charge state close to+ 3 and was effectively protected from reaction with water and oxygen by the enclosing fullerene cage. Unlike theoretical expectation, the electronic state of Ce@C82 is formally described as Ce+3@C3-82.

Enhanced separation of rare earth elements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lyon, K.; Greenhalgh, M.; Herbst, R. S.

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 earthmore » 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.« less

Cerium-based, intermetallic-strengthened aluminum casting alloy: High-volume co-product development

DOE PAGES

Sims, Zachary C.; Weiss, David; McCall, S. K.; ...

2016-05-23

Here, several rare earth elements are considered by-products to rare earth mining efforts. By using one of these by-product elements in a high-volume application such as aluminum casting alloys, the supply of more valuable rare earths can be globally stabilized. Stabilizing the global rare earth market will decrease the long-term criticality of other rare earth elements. The low demand for Ce, the most abundant rare earth, contributes to the instability of rare earth extraction. In this article, we discuss a series of intermetallic-strengthened Al alloys that exhibit the potential for new high-volume use of Ce. The castability, structure, and mechanicalmore » properties of binary, ternary, and quaternary Al-Ce based alloys are discussed. We have determined Al-Ce based alloys to be highly castable across a broad range of compositions. Nanoscale intermetallics dominate the microstructure and are the theorized source of the high ductility. In addition, room-temperature physical properties appear to be competitive with existing aluminum alloys with extended high-temperature stability of the nanostructured intermetallic.« less

Sources of Extraterrestrial Rare Earth Elements:To the Moon and Beyond

NASA Astrophysics Data System (ADS)

McLeod, C. L.; Krekeler, M. P. S.

2017-08-01

The resource budget of Earth is limited. Rare-earth elements (REEs) are used across the world by society on a daily basis yet several of these elements have <2500 years of reserves left, based on current demand, mining operations, and technologies. With an increasing population, exploration of potential extraterrestrial REE resources is inevitable, with the Earth's Moon being a logical first target. Following lunar differentiation at 4.50-4.45 Ga, a late-stage (after 99% solidification) residual liquid enriched in Potassium (K), Rare-earth elements (REE), and Phosphorus (P), (or "KREEP") formed. Today, the KREEP-rich region underlies the Oceanus Procellarum and Imbrium Basin region on the lunar near-side (the Procellarum KREEP Terrain, PKT) and has been tentatively estimated at preserving 2.2 × 10^8 km^3 of KREEP-rich lithologies. The majority of lunar samples (Apollo, Luna, or meteoritic samples) contain REE-bearing minerals as trace phases, e.g., apatite and/or merrillite, with merrillite potentially contributing up to 3% of the PKT. Other lunar REE-bearing lunar phases include monazite, yittrobetafite (up to 94,500 ppm yttrium), and tranquillityite (up to 4.6 wt % yttrium, up to 0.25 wt % neodymium), however, lunar sample REE abundances are low compared to terrestrial ores. At present, there is no geological, mineralogical, or chemical evidence to support REEs being present on the Moon in concentrations that would permit their classification as ores. However, the PKT region has not yet been mapped at high resolution, and certainly has the potential to yield higher REE concentrations at local scales (<10s of kms). Future lunar exploration and mapping efforts may therefore reveal new REE deposits. Beyond the Moon, Mars and other extraterrestrial materials are host to REEs in apatite, chevkinite-perrierite, merrillite, whitlockite, and xenotime. These phases are relatively minor components of the meteorites studied to date, constituting <0.6% of the total sample

Rare earth elements geochemistry in springs from Taftan geothermal area SE Iran

NASA Astrophysics Data System (ADS)

Shakeri, Ata; Ghoreyshinia, Sayedkazem; Mehrabi, Behzad; Delavari, Morteza

2015-10-01

Concentrations of rare earth elements (REEs) were determined in springs and andesitic-dacitic rocks of Taftan geothermal field. Hydrochemical results of major ions indicate that thermal springs are Na-SO4-Cl and Ca-SO4-Cl types. Concentrations of REEs are in ranges of 10- 4 to 1.2 and 49 to 62 times of chondrite for springwater and rock samples, respectively. The thermal (STS and TTS) and the cold (APS) springs with low pH values exhibit a very high REE contents (0.64 to 3.15 mg/l). Saturation index indicates that Fe and Al phases can control dissolved REE concentration in FTS and PF cold springs. The speciation of REE complexes indicates dominant presence of LnSO4+ and free ion in the Taftan thermal springs. In APS cold spring with pH 4, fluoride complexes are dominate over the free ion and sulfate species, while in PF and FTS cold springs with pH 6.4 and 7, respectively, carbonate complexes (LnCO3+) are predominant species. Chondrite-normalized pattern for the low-pH waters show very distinctive gull-wing patterns, characteristic feature of acid-sulfate geothermal systems, and are similar to those of the host rocks. Chemical characteristics of rare earth elements in spring and volcanic rock samples indicate that REEs are originated from the andesitic-dacitic host rocks. Whole-rock-normalized REE patterns and petrographic evidences show that rare earth elements leached mainly from marginal alteration of minerals and matrix decomposition in volcanic rocks. In chondrite-normalized REE patterns, significant negative Eu anomaly in the cold springs compare to the thermal and acidic springs indicates that alteration of plagioclase is more intense in the later, corresponding to increasing in temperature and acidic state of reactant water.

Unusual Phase Diagram of CeOs 4Sb 12

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ho, P. -C.; Goddard, P. A.; Maple, M. B.

2017-03-01

Filled skutterudite compounds, with the formula MT 4X 12, where M is an alkali metal, alkaline-earth, lanthanide, or actinide, T is Fe, Ru, or Os, and X is P, As, or Sb, display a wide variety of interesting phenomena caused by strong electron correlations [1]. Among these, the three compounds CeOs 4Sb 12, PrOs 4Sb 12, and NdOs 4Sb 12, formed by employing Periodic Table neighbors for M, span the range from an antiferromagnetic (AFM) semimetal (M = Ce) via a 1.85 K unconventional (quadrupolar-fluctuation mediated) superconductor (M = Pr) to a 1 K ferromagnet (FM; M = Nd). Inmore » the course of an extended study of these compounds, we uncovered an unusual phase diagram for CeOs 4Sb 12.« less

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

DTIC Science & Technology

2016-02-02

Earths ”, MS&T15-Materials Science and Technology 2015 Conference, Columbus, Ohio, October 4-8, 2015. 3. Dulikrvich, G.S., Reddy, S., Orlande, H.R.B...Schwartz, J.and Koch, C.C., “Multi-Objective Design and Optimization of Hard Magnetic Alloys Free of Rare Earths ”, MS&T15-Materials Science and Technology...AFRL-AFOSR-VA-TR-2016-0091 (BRI) Direct and Inverse Design Optimization of Magnetic Alloys with Minimized Use of Rare Earth Elements George

[Rare earth elements content in farmland soils and crops of the surrounding copper mining and smelting plant in Jiangxi province and evaluation of its ecological risk].

PubMed

Jin, Shu-Lan; Huang, Yi-Zong; Wang, Fei; Xu, Feng; Wang, Xiao-Ling; Gao, Zhu; Hu, Ying; Qiao Min; Li, Jin; Xiang, Meng

2015-03-01

Rare earth elements content in farmland soils and crops of the surrounding copper mining and smelting plant in Jiangxi province was studied. The results showed that copper mining and smelting could increase the content of rare earth elements in soils and crops. Rare earth elements content in farmland soils of the surrounding Yinshan Lead Zinc Copper Mine and Guixi Smelting Plant varied from 112.42 to 397.02 mg x kg(-1) and 48.81 to 250.06 mg x kg(-1), and the average content was 254.84 mg x kg(-1) and 144.21 mg x kg(-1), respectively. The average contents of rare earth elements in soils in these two areas were 1.21 times and 0.68 times of the background value in Jiangxi province, 1.36 times and 0.77 times of the domestic background value, 3.59 times and 2.03 times of the control samples, respectively. Rare earth elements content in 10 crops of the surrounding Guixi Smelting Plant varied from 0.35 to 2.87 mg x kg(-1). The contents of rare earth elements in the leaves of crops were higher than those in stem and root. The contents of rare earth elements in Tomato, lettuce leaves and radish leaves were respectively 2.87 mg x kg(-1), 1.58 mg x kg(-1) and 0.80 mg x kg(-1), which were well above the hygienic standard limit of rare earth elements in vegetables and fruits (0.70 mg x kg(-1)). According to the health risk assessment method recommended by America Environmental Protection Bureau (USEPA), we found that the residents' lifelong average daily intake of rare earth elements was 17.72 mg x (kg x d)(-1), lower than the critical value of rare earth elements damage to human health. The results suggested that people must pay attention to the impact of rare earth elements on the surrounding environment when they mine and smelt copper ore in Jiangxi.

Quantifying and Comparing Effects of Climate Engineering Methods on the Earth System

NASA Astrophysics Data System (ADS)

Sonntag, Sebastian; Ferrer González, Miriam; Ilyina, Tatiana; Kracher, Daniela; Nabel, Julia E. M. S.; Niemeier, Ulrike; Pongratz, Julia; Reick, Christian H.; Schmidt, Hauke

2018-02-01

To contribute to a quantitative comparison of climate engineering (CE) methods, we assess atmosphere-, ocean-, and land-based CE measures with respect to Earth system effects consistently within one comprehensive model. We use the Max Planck Institute Earth System Model (MPI-ESM) with prognostic carbon cycle to compare solar radiation management (SRM) by stratospheric sulfur injection and two carbon dioxide removal methods: afforestation and ocean alkalinization. The CE model experiments are designed to offset the effect of fossil-fuel burning on global mean surface air temperature under the RCP8.5 scenario to follow or get closer to the RCP4.5 scenario. Our results show the importance of feedbacks in the CE effects. For example, as a response to SRM the land carbon uptake is enhanced by 92 Gt by the year 2100 compared to the reference RCP8.5 scenario due to reduced soil respiration thus reducing atmospheric CO2. Furthermore, we show that normalizations allow for a better comparability of different CE methods. For example, we find that due to compensating processes such as biogeophysical effects of afforestation more carbon needs to be removed from the atmosphere by afforestation than by alkalinization to reach the same global warming reduction. Overall, we illustrate how different CE methods affect the components of the Earth system; we identify challenges arising in a CE comparison, and thereby contribute to developing a framework for a comparative assessment of CE.

Evaluation of a SiPM array coupled to a Gd3Al2Ga3O12:Ce (GAGG:Ce) discrete scintillator.

PubMed

David, S; Georgiou, M; Fysikopoulos, E; Loudos, G

2015-11-01

In this study, we present the results of the evaluation of the SensL ArraySL-4 photo-detector, coupled to a 6 × 6 GAGG:Ce scintillator array, with 2 × 2 × 5 mm(3) crystal size elements for possible applications in medical imaging detectors with focus in PET applications. Experimental evaluation was carried out with (22)Na and (137)Cs radioactive sources and the parameters studied were energy resolution and peak to valley ratio. ArraySL-4 is a commercially available, 4 × 4 array detector covering an active area of 13.4 mm(2). The GAGG:Ce scintillator array used in this study has 0.1 mm thickness BaSO4 reflector material between the crystal elements. A symmetric resistive voltage division matrix was applied, which reduces the 16 outputs of the array to 4 position signals. A Field Programmable Gate Array was used for triggering and digital processing of the signal pulses acquired using free running Analog to Digital Converters. Raw images and horizontal profiles of the 6 × 6 GAGG:Ce scintillator array produced under 511 keV and 662 keV excitation are illustrated. Moreover, the energy spectra obtained with (22)Na and (137)Cs radioactive sources from a single 2 × 2 × 5 mm(3) GAGG:Ce scintillator are shown. The peak to valley ratio and the mean energy resolution values are reported. The acquired raw image of the GAGG:Ce crystal array under 511 keV excitation shows a clear visualization of all discrete scintillator elements with a mean peak to valley ratio equal to 40. The mean energy resolution was measured equal to 10.5% and 9% respectively under 511 keV and 662 keV irradiation. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Compositional and phase relations among rare earth element minerals

NASA Technical Reports Server (NTRS)

Burt, D. M.

1989-01-01

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

Blood levels of toxic metals and rare earth elements commonly found in e-waste may exert subtle effects on hemoglobin concentration in sub-Saharan immigrants.

PubMed

Henríquez-Hernández, Luis Alberto; Boada, Luis D; Carranza, Cristina; Pérez-Arellano, José Luis; González-Antuña, Ana; Camacho, María; Almeida-González, Maira; Zumbado, Manuel; Luzardo, Octavio P

2017-12-01

Pollution by heavy metals and more recently by rare earth elements (REE) and other minor elements (ME) has increased due in part to their high use in technological and electronic devices. This contamination can become very relevant in those sites where e-waste is improperly processed, as it is the case in many countries of the African continent. Exposure to some toxic elements has been associated to certain hematological disorders, specifically anemia. In this study, the concentrations of 48 elements (including REE and other ME) were determined by ICP-MS in whole blood samples of sub-Saharan immigrants with anemia (n=63) and without anemia (n=78). We found that the levels of Fe, Cr, Cu, Mn, Mo, and Se were significantly higher in the control group than in the anemia group, suggesting that anemia was mainly due to nutritional deficiencies. However, since other authors have suggested that in addition to nutritional deficiency, exposure to some elements may influence hemoglobin levels, we wanted to explore the role of a broad panel of toxic and "emerging" elements in hemoglobin deficiency. We found that the levels of Ag, As, Ba, Bi, Ce, Eu, Er, Ga, La, Nb, Nd, Pb, Pr, Sm, Sn, Ta, Th, Tl, U and V were higher in anemic participants than in controls. For most of these elements an inverse correlation with hemoglobin concentration was found. Some of them also correlated inversely with blood iron levels, pointing to the possibility that a higher rate of intestinal uptake of these could exist in relation to a nutritional deficiency of iron. However, the higher levels of Pb, and the group of REE and other ME in anemic participants were independent of iron levels, pointing to the possibility that these elements could play a role in the development of anemia. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sustainability evaluation of essential critical raw materials: cobalt, niobium, tungsten and rare earth elements

NASA Astrophysics Data System (ADS)

Tkaczyk, A. H.; Bartl, A.; Amato, A.; Lapkovskis, V.; Petranikova, M.

2018-05-01

The criticality of raw materials has become an important issue in recent years. As the supply of certain raw materials is essential for technologically-advanced economies, the European Commission and other international counterparts have started several initiatives to secure reliable and unhindered access to raw materials. Such efforts include the EU Raw Materials Initiative, European Innovation Partnership on Raw Materials, US Critical Materials Institute, and others. In this paper, the authors present a multi-faceted and multi-national review of the essentials for the critical raw materials (CRMs) Co, Nb, W, and rare earth elements (REEs). The selected CRMs are of specific interest as they are considered relevant for emerging technologies and will thus continue to be of increasing major economic importance. This paper presents a ‘sustainability evaluation’ for each element, including essential data about markets, applications and recycling, and possibilities for substitution have been summarized and analysed. All the presented elements are vital for the advanced materials and processes upon which modern societies rely. These elements exhibit superior importance in ‘green’ applications and products subject to severe conditions. The annual production quantities are quite low compared to common industrial metals. Of the considered CRMs, only Co and REE gross production exceed 100 000 t. At the same time, the prices are quite high, with W and Nb being in the range of 60 USD kg‑1 and some rare earth compounds costing almost 4000 USD kg‑1. Despite valiant effort, in practice some of the considered elements are de facto irreplaceable for many specialized applications, at today’s technological level. Often, substitution causes a significant loss of quality and performance. Furthermore, possible candidates for substitution may be critical themselves or available in considerably low quantities. It can be concluded that one preferred approach for the

Computation of Pressurized Gas Bearings Using CE/SE Method

NASA Technical Reports Server (NTRS)

Cioc, Sorin; Dimofte, Florin; Keith, Theo G., Jr.; Fleming, David P.

2003-01-01

The space-time conservation element and solution element (CE/SE) method is extended to compute compressible viscous flows in pressurized thin fluid films. This numerical scheme has previously been used successfully to solve a wide variety of compressible flow problems, including flows with large and small discontinuities. In this paper, the method is applied to calculate the pressure distribution in a hybrid gas journal bearing. The formulation of the problem is presented, including the modeling of the feeding system. the numerical results obtained are compared with experimental data. Good agreement between the computed results and the test data were obtained, and thus validate the CE/SE method to solve such problems.

Recycling of Rare Earth Elements

NASA Astrophysics Data System (ADS)

Lorenz, Tom; Bertau, Martin

2017-01-01

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

Influence of yttrium content on the location of rare earth ions in LYSO:Ce crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, Dongzhou, E-mail: dongzhou_ding@mail.sic.ac.cn; R and D Center of Shanghai Institute of Ceramics, No. 588 Heshuo Road, Shanghai 201899; Weng, Linhong

2014-01-15

Single-crystal X-ray diffraction (SCD), X-ray fluorescence (XRF), inductively coupled plasma optical emission spectroscopy (ICP-OES) and X-ray excited luminescence (XEL) measurements were performed to investigate structure details and segregation coefficients of (Lu{sub 1−x}Y{sub x}){sub 2}SiO{sub 5}:Ce (x=0 at%, 8.7 at%, 25.7 at%, 44.7 at%, 65.7 at%, 87.9 at% and 100 at%). Y{sup 3+} cations were found to have a preferential occupation for RE1 site (7-oxygen-coordinated) over RE2 site (6-oxygen-coordinated), which results in a greater increase of cell parameter c than that of a with increase in Y content due to LYSO's microstructure characteristics. Results presented here revealed that the less themore » difference in electronegativity and effective ionic radius between the two ions, the easier substitution of one ion by the other, and hence the higher segregation coefficients. Besides, the contribution of luminescence of Ce1 and Ce2 in the whole XEL was evaluated, and the location of Ce{sup 3+} ion was discussed. - Graphical abstract: Segregation coefficients of (Lu{sub 1−x}Y{sub x}){sub 2}SiO{sub 5}:Cce:italic> at RT/ce:italic>. Display Omitted.« less

Preface to highly siderophile element constraints on Earth and planetary processes

NASA Astrophysics Data System (ADS)

Riches, Amy J. V.

2017-11-01

The geochemical properties of the highly siderophile elements (HSEs; Os, Ir, Ru, Rh, Pt, Pd, Re and Au) - being strongly iron-loving, but also chalcophile (i.e., having an affinity for sulphide), and generally occurring at ultra trace levels in silicate rocks, their weathered products, and oceanic waters - mean that this suite of elements and their isotopic compositions are useful in tracing a wide variety of processes. Thus, the HSEs are useful probes with which to tackle major research questions pertinent to past and present day change at a variety of scales and in a range of Earth and other-worldly environments by constraining reservoir compositions, chemical drivers, and the timing of key events and/or transformation rates.

Quantification of rare earth elements using laser-induced breakdown spectroscopy

DOE PAGES

Martin, Madhavi; Martin, Rodger C.; Allman, Steve; ...

2015-10-21

In this paper, a study of the optical emission as a function of concentration of laser-ablated yttrium (Y) and of six rare earth elements, europium (Eu), gadolinium (Gd), lanthanum (La), praseodymium (Pr), neodymium (Nd), and samarium (Sm), has been evaluated using the laser-induced breakdown spectroscopy (LIBS) technique. Statistical methodology using multivariate analysis has been used to obtain the sampling errors, coefficient of regression, calibration, and cross-validation of measurements as they relate to the LIBS analysis in graphite-matrix pellets that were doped with elements at several concentrations. Each element (in oxide form) was mixed in the graphite matrix in percentages rangingmore » from 1% to 50% by weight and the LIBS spectra obtained for each composition as well as for pure oxide samples. Finally, a single pellet was mixed with all the elements in equal oxide masses to determine if we can identify the elemental peaks in a mixed pellet. This dataset is relevant for future application to studies of fission product content and distribution in irradiated nuclear fuels. These results demonstrate that LIBS technique is inherently well suited for the future challenge of in situ analysis of nuclear materials. Finally, these studies also show that LIBS spectral analysis using statistical methodology can provide quantitative results and suggest an approach in future to the far more challenging multielemental analysis of ~ 20 primary elements in high-burnup nuclear reactor fuel.« less

GAP Noise Computation By The CE/SE Method

NASA Technical Reports Server (NTRS)

Loh, Ching Y.; Chang, Sin-Chung; Wang, Xiao Y.; Jorgenson, Philip C. E.

2001-01-01

A typical gap noise problem is considered in this paper using the new space-time conservation element and solution element (CE/SE) method. Implementation of the computation is straightforward. No turbulence model, LES (large eddy simulation) or a preset boundary layer profile is used, yet the computed frequency agrees well with the experimental one.

Assessment of Bioavailable Concentrations of Germanium and Rare Earth Elements in the Rhizosphere of White Lupin (Lupinus albus L.)

NASA Astrophysics Data System (ADS)

Wiche, Oliver; Fischer, Ronny; Moschner, Christin; Székely, Balázs

2015-04-01

Concentrations of Germanium (Ge) and Rare Earth Elements in soils are estimated at 1.5 mg kg -1 (Ge), 25 mg kg -1 (La) and 20 mg kg -1 (Nd), which are only roughly smaller than concentrations of Pb and Zn. Germanium and rare earth elements are thus not rare but widely dispersed in soils and therefore up to date, only a few minable deposits are available. An environmental friendly and cost-effective way for Ge and rare earth element production could be phytomining. However, the most challenging part of a phytomining of these elements is to increase bioavailable concentrations of the elements in soils. Recent studies show, that mixed cultures with white lupine or other species with a high potential to mobilize trace metals in their rhizosphere due to an acidification of the soil and release of organic acids in the root zone could be a promising tool for phytomining. Complexation of Ge and rare earth elements by organic acids might play a key role in controlling bioavailability to plants as re-adsorption on soil particles and precipitation is prevented and thus, concentrations in the root zone of white lupine increase. This may also allow the complexes to diffuse along a concentration gradient to the roots of mixed culture growing species leading to enhanced plant uptake. However, to optimize mixed cultures it would be interesting to know to which extend mobilization of trace metals is dependent from chemical speciation of elements in soil due to the interspecific interaction of roots. A method for the identification of complexes of germanium and rare earth elements with organic acids, predominantly citric acid in the rhizosphere of white lupine was developed and successfully tested. The method is based on coupling of liquid chromatography with ICP-MS using a zic-philic column (SeQuant). As a preliminary result, we were able to show that complexes of germanium with citric acid exist in the rhizosphere of white lupin, what may contribute to the bioavailability of this

Parallel CE/SE Computations via Domain Decomposition

NASA Technical Reports Server (NTRS)

Himansu, Ananda; Jorgenson, Philip C. E.; Wang, Xiao-Yen; Chang, Sin-Chung

2000-01-01

This paper describes the parallelization strategy and achieved parallel efficiency of an explicit time-marching algorithm for solving conservation laws. The Space-Time Conservation Element and Solution Element (CE/SE) algorithm for solving the 2D and 3D Euler equations is parallelized with the aid of domain decomposition. The parallel efficiency of the resultant algorithm on a Silicon Graphics Origin 2000 parallel computer is checked.

Micron-Scale Correlations Among Ti, P, Ce, and Y in Hadean Jack Hills Zircons

NASA Astrophysics Data System (ADS)

Hofmann, A. E.; Cavosie, A. J.; Valley, J. W.; Eiler, J. M.

2007-12-01

Detrital zircons and the inclusions found therein are our only mineralogical constraints on geologic events that occurred on the Hadean Earth. These zircons are commonly small (ca. <100 μm in the longest dimension) and preserve micron to sub-micron chemical zonations indicative of a dynamic petrological history. Trace elements within zircon are of particular interest because concentrations and ratios of these elements can provide information regarding chemical and physical conditions during zircon growth. In this study, we analyzed Hadean-age detrital zircons from Archean metasediment in the Jack Hills (Australia) using the Caltech Microanalysis Center Cameca NanoSIMS 50L. Trace elements analyzed included Ti, P, Ce, and Y. Ti- thermometry [1,2,3] can potentially constrain growth and/or re-equilibration temperatures of zircons; P, Ce, and Y are known to enter the zircon lattice by the coupled xenotime-type substitution mechanism: (Y, REE)3+ + P5+ = Zr4+ + Si4+ [5]. The 89Y/28Si ratio was observed to correlate with, and was used as a proxy for, cathodoluminescence (CL) banding. Growth features manifested in CL (e.g., sector, oscillatory zoning) were observed in all zircons analyzed. CL zones vary from <1 μm to several microns in width; therefore, the NanoSIMS---with a beam diameter resolved to ca. 250 nm on the sample surface when operating with an O- primary beam---is uniquely suited for this scale of analysis. Regions displaying CL banding were imaged as 20 x 20 μm areas. All elements were normalized to 28Si; 49Ti/28Si ratios were converted to [Ti] via calibration based on analyses of synthetic, high-Ti zircons (provided by B. Watson) that were independently analyzed on Caltech's JEOL JXA-8200 electron microprobe. We observe three types of relationships between trace element distribution and CL banding in the zircons imaged: 1) strong positive correlations between CL banding, P, Ce, and Ti; 2) subtle positive correlations between CL banding, P, Ce, and Ti; 3) no

[Effects of rare earth elements on soil fauna community structure and their ecotoxicity to Holotrichia parallela].

PubMed

Li, Guiting; Jiang, Junqi; Chen, Jie; Zou, Yunding; Zhang, Xincai

2006-01-01

By the method of OECD filter paper contact, this paper studied the effects of applied rare earth elements on soil fauna community structure and their ecological toxicity to Holotrichia parallela in bean field. The results showed that there were no significant differences between the treatments and the control in soil fauna species, quantity of main species, and diversity index. Urgent and chronic toxic test showed that the differences between the treatments and the control were not significant. It was suggested that within the range of test dosages, rare earth elements had little ecological toxicity to Holotrichia parallela, and did not change the soil fauna community structure.

A chemical-spectrochemical method for the determination of rare earth elements and thorium in cerium minerals

USGS Publications Warehouse

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

1954-01-01

In a combined chemical-spectrochemical procedure for quantitatively determining rare earth elements in cerium minerals, cerium is determined volumetrically, a total rare earths plus thoria precipitate is separated chemically, the ceria content of the precipitate is raised to 80??0 percent by adding pure ceria, and the resulting mixture is analyzed for lanthanum, praseodymium, neodymium, samarium, gadolinium, yttrium, and thorium spectrochemically by means of the d.c. carbon arc. Spectral lines of singly ionized cerium are used as internal standard lines in the spectrochemical determination which is patterned after Fassel's procedure [1]. Results of testing the method with synthetic mixtures of rare earths and with samples of chemically analyzed cerium minerals show that the coefficient of variation for a quadruplicate determination of any element does not exceed 5??0 (excepting yttrium at concentrations less than 1 percent) and that the method is free of serious systematic error. ?? 1954.

The Distribution of Heat-Producing Radioactive Elements in the Deep Earth

NASA Astrophysics Data System (ADS)

Chidester, Bethany A.

The Earth is a heat engine, where large differences in temperature between the interior and the surface drive large-scale movement that manifests as plate tectonics and the geomagnetic field that protects us from the Sun's harmful charged particles. Decay of the long-lived radioactive elements U, Th, and K is expected to contribute as much as 45% of the current heat production in the Earth, and that heat production was five times higher early in Earth's history. It is unclear how this heat source affects the thermal and dynamic evolution of the Earth's core and mantle and how that contribution has changed over geologic time. This dissertation addresses this problem in several different ways. This work represents the first high-pressure, high-temperature metal-silicate partitioning experiments for U, Th, and K in the laser-heated diamond anvil cell at conditions relevant to core formation. A chemical model is developed using parameterization of these partitioning data to constrain the concentrations of each of these elements in the core. Using a numerical calculation, it is then determined how that radioactive heat would contribute to the core's energy and entropy budget through time. One finds that, despite its strong lithophile nature at the surface, U partitions significantly into the metallic phase at increasing temperatures. This may be due to a decrease in U valence from 4+ to 2+ in high-pressure silicate melts, which our data supports. However, K and Th do not exhibit a similar change in behavior at these conditions, and this may drive fractionation between U and Th in the deep mantle. At the most extreme conditions of core formation, enough U could exist in the core to produce up to 4.4 TW of heat 4.5 billion years ago. Potassium could produce much less heat than U early on (< 1 TW), and due to its short half-life, would have decayed away much faster. While this energy source is significantly greater than was previously thought to be possible, it is likely

Rare Earth Element Concentrations and Fractionation Patterns Along Groundwater Flow Paths in Two Different Aquifer Types (i.e., Sand vs. Carbonate)

NASA Astrophysics Data System (ADS)

Johannesson, K. H.; Tang, J.

2003-12-01

Groundwater samples were collected in two different types of aquifer (i.e., Carrizo Sand Aquifer, Texas and Upper Floridan carbonate Aquifer, west-central Florida) to study the concentrations, fractionation, and speciation of rare earth elements (REE) along groundwater flow paths in each aquifer. Major solutes and dissolved organic carbon (DOC) were also measured in these groundwaters. The Carrizo Sand aquifer was sampled in October 2002 and June 2003, whereas, to date, we have only sampled the Floridan once (i.e., June 2003). The data reveal no significant seasonal differences in major solute and REE concentrations for the Carrizo. In Carrizo sand aquifer, groundwaters from relatively shallow wells (i.e., less than 167 m) in the recharge zone are chiefly Ca-Na-HCO3-Cl type waters. With flow down-gradient the groundwaters shift composition to the Na-HCO3 waters. pH and alkalinity initially decrease with flow away from the recharge zone before increasing again down-gradient. DOC is generally low (0.65 mg/L) along the flow path. REE concentrations are highest in groundwaters from the recharge zone (Nd 40.5 pmol/kg), and decrease substantially with flow down-gradient reaching relatively low and stable values (Nd 4.1-8.6 pmol/kg) roughly 10 km from the recharge zone. Generally, Carrizo groundwaters exhibit HREE-enriched shale-normalized patterns. The HREE enrichments are especially strong for waters from the recharge zone [(Yb/Nd)SN =1.7-5.6], whereas down-gradient (deep) groundwaters have flatter patterns [(Yb/Nd)SN =0.7-2.5]. All groundwaters have slightly positive Eu anomalies (Eu/Eu* 0.09-0.14) and negative Ce anomalies (Ce/Ce* -0.85 - -0.07). In the Upper Floridan Aquifer, Ca, Mg, SO4, and Cl concentrations generally increase along groundwater flow path, whereas pH and alkalinity generally decrease. DOC is higher (0.64 - 2.29 mg/L) than in the Carrizo and initially increases along the flow path and then decreases down-gradient. LREE (Nd) concentrations generally

Adding the s-Process Element Cerium to the APOGEE Survey: Identification and Characterization of Ce II Lines in the H-band Spectral Window

NASA Astrophysics Data System (ADS)

Cunha, Katia; Smith, Verne V.; Hasselquist, Sten; Souto, Diogo; Shetrone, Matthew D.; Allende Prieto, Carlos; Bizyaev, Dmitry; Frinchaboy, Peter; García-Hernández, D. Anibal; Holtzman, Jon; Johnson, Jennifer A.; Jőnsson, Henrik; Majewski, Steven R.; Mészáros, Szabolcs; Nidever, David; Pinsonneault, Mark; Schiavon, Ricardo P.; Sobeck, Jennifer; Skrutskie, Michael F.; Zamora, Olga; Zasowski, Gail; Fernández-Trincado, J. G.

2017-08-01

Nine Ce II lines have been identified and characterized within the spectral window observed by the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey (between λ1.51 and 1.69 μm). At solar metallicities, cerium is an element that is produced predominantly as a result of the slow capture of neutrons (the s-process) during asymptotic giant branch stellar evolution. The Ce II lines were identified using a combination of a high-resolution (R=λ /δ λ ={{100,000}}) Fourier Transform Spectrometer (FTS) spectrum of α Boo and an APOGEE spectrum (R = 22,400) of a metal-poor, but s-process enriched, red giant (2M16011638-1201525). Laboratory oscillator strengths are not available for these lines. Astrophysical gf-values were derived using α Boo as a standard star, with the absolute cerium abundance in α Boo set by using optical Ce II lines that have precise published laboratory gf-values. The near-infrared Ce II lines identified here are also analyzed, as consistency checks, in a small number of bright red giants using archival FTS spectra, as well as a small sample of APOGEE red giants, including two members of the open cluster NGC 6819, two field stars, and seven metal-poor N- and Al-rich stars. The conclusion is that this set of Ce II lines can be detected and analyzed in a large fraction of the APOGEE red giant sample and will be useful for probing chemical evolution of the s-process products in various populations of the Milky Way.

Composition of the earth's upper mantle. II - Volatile trace elements in ultramafic xenoliths

NASA Technical Reports Server (NTRS)

Morgan, J. W.; Wandless, G. A.; Petrie, R. K.; Irving, A. J.

1980-01-01

Radiochemical neutron activation analysis was used to determine the nine volatile elements Ag, Bi, Cd, In, Sb, Se, Te, Tl, and Zn in 19 ultramafic rocks, consisting mainly of spinel and garnet lherzolites. A sheared garnet lherzolite, PHN 1611, may approximate undepleted mantle material and tends to have a higher volatile element content than the depleted mantle material represented by spinel lherzolites. Comparisons of continental basalts with PHN 1611 and of oceanic ridge basalts with spinel lherzolites show similar basalt: source material partition factors for eight of the nine volatile elements, Sb being the exception. The strong depletion of Te and Se in the mantle, relative to lithophile elements of similar volatility, suggests that 97% of the earth's S, Se and Te may be in the outer core.

[Indirect determination of rare earth elements in Chinese herbal medicines by hydride generation-atomic fluorescence spectrometry].

PubMed

Zeng, Chao; Lu, Jian-Ping; Xue, Min-Hua; Tan, Fang-Wei; Wu, Xiao-Yan

2014-07-01

Based on their similarity in chemical properties, rare earth elements were able to form stable coordinated compounds with arsenazo III which were extractable into butanol in the presence of diphenylguanidine. The butanol was removed under reduced pressure distillation; the residue was dissolved with diluted hydrochloric acid. As was released with the assistance of KMnO4 and determined by hydrogen generation-atomic fluorescence spectrometry in terms of rare earth elements. When cesium sulfate worked as standard solution, extraction conditions, KMnO4 amount, distillation temperature, arsenazo III amount, interfering ions, etc were optimized. The accuracy and precision of the method were validated using national standard certified materials, showing a good agreement. Under optimum condition, the linear relationship located in 0.2-25 microg x mL(-1) and detection limit was 0.44 microg x mL(-1). After the herbal samples were digested with nitric acid and hydrogen peroxide, the rare earth elements were determined by this method, showing satisfactory results with relative standard deviation of 1.3%-2.5%, and recoveries of 94.4%-106.0%. The method showed the merits of convenience and rapidness, simple instrumentation and high accuracy. With the rare earths enriched into organic phase, the separation of analytes from matrix was accomplished, which eliminated the interference. With the residue dissolved by diluted hydrochloric acid after the solvent was removed, aqueous sample introduction eliminated the impact of organic phase on the tubing connected to pneumatic pump.

The effect of melt composition on the partitioning of trace elements between titanite and silicate melt

NASA Astrophysics Data System (ADS)

Prowatke, S.; Klemme, S.

2003-04-01

The aim of this study is to systematically investigate the influence of melt composition on the partitioning of trace elements between titanite and different silicate melts. Titanite was chosen because of its important role as an accessory mineral, particularly with regard to intermediate to silicic alkaline and calc-alkaline magmas [e.g. 1] and of its relative constant mineral composition over a wide range of bulk compositions. Experiments at atmospheric pressure were performed at temperatures between 1150°C and 1050°C. Bulk compositions were chosen to represent a basaltic andesite (SH3 - 53% SiO2), a dacite (SH2 - 65 SiO2) and a rhyolite (SH1 - 71% SiO2). Furthermore, two additional experimental series were conducted to investigate the effect of Al-Na and the Na-K ratio of melts on partitioning. Starting materials consisted of glasses that were doped with 23 trace elements including some selected rare earth elements (La, Ce, Pr, Sm, Gd, Lu), high field strength elements (Zr, Hf, Nb, Ta) and large ion lithophile elements (Cs, Rb, Ba) and Th and U. The experimental run products were analysed for trace elements using secondary ion mass spectrometry at Heidelberg University. Preliminary results indicate a strong effect of melt composition on trace element partition coefficients. Partition coefficients for rare-earth elements uniformly show a convex-upward shape [2, 3], since titanite accommodates the middle rare-earth elements more readily than the light rare-earth elements or the heavy rare-earth elements. Partition coefficients for the rare-earth elements follow a parabolic trend when plotted against ionic radius. The shape of the parabola is very similar for all studied bulk compositions, the position of the parabola, however, is strongly dependent on bulk composition. For example, isothermal rare-earth element partition coefficients (such as La) are incompatible (D<1) in alkali-rich silicate melts and strongly compatible (D>>1) in alkali-poor melt compositions

Rare earth element and rare metal inventory of central Asia

USGS Publications Warehouse

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.

Facile and Efficient Decontamination of Thorium from Rare Earths Based on Selective Selenite Crystallization.

PubMed

Wang, Yaxing; Lu, Huangjie; Dai, Xing; Duan, Tao; Bai, Xiaojing; Cai, Yawen; Yin, Xuemiao; Chen, Lanhua; Diwu, Juan; Du, Shiyu; Zhou, Ruhong; Chai, Zhifang; Albrecht-Schmitt, Thomas E; Liu, Ning; Wang, Shuao

2018-02-19

The coexistence of radioactive contaminants (e.g., thorium, uranium, and their daughters) in rare earth minerals introduces significant environmental, economic, and technological hurdles in modern rare earth production. Efficient, low cost, and green decontamination strategies are therefore desired to ameliorate this problem. We report here a single-step and quantitative decontamination strategy of thorium from rare earths based on a unique periodic trend in the formation of crystalline selenite compounds across the lanthanide series, where Ce(III) is fully oxidized in situ to Ce(IV). This gives rise to a crystallization system that is highly selective to trap tetravalent f-blocks while all other trivalent lanthanides completely remain in solution when coexist. These results are bolstered by first-principles calculations of lattice energies and an examination of bonding in these compounds. This system is contrasted with typical natural and synthetic systems, where trivalent and tetravalent f-block elements often cocrystallize. The separation factors after one round of crystallization were determined from binary systems of Th(IV)/La(III), Th(IV)/Eu(III), and Th(IV)/Yb(III) to reach 2.1 × 10 5 , 1.2 × 10 5 , and 9 × 10 4 , respectively. Selective crystallization of thorium from a simulated monazite composite yields a separation factor of 1.9 × 10 3 with nearly quantitative removal of thorium.

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

NASA Technical Reports Server (NTRS)

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

1974-01-01

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

Identification of species of the Euterpe genus by rare earth elements using inductively coupled plasma mass spectrometry and linear discriminant analysis.

PubMed

Santos, Vívian Silva; Nardini, Viviani; Cunha, Luís Carlos; Barbosa, Fernando; De Almeida Teixeira, Gustavo Henrique

2014-06-15

The açaí (Euterpe oleracea Mart.) and juçara (Euterpe edulis Mart.) produce similar fruits which are rich in energy, minerals, vitamins and natural compounds with antioxidant and anti-inflammatory properties. Although the drink obtained from these species is similar, it is important to develop tools to establish the identity of the fruit species and growing regions. To assess claims of origin and for other purposes, we use multivariate analysis to investigate the differentiation of açaí and juçara fruits based on rare earth element (REE) content determined by Inductively Coupled Plasma Mass Spectrometry. REE content, in particular Sm, Th, La, Pr, Gd, and especially Ce and Nd varied between species. PCA analysis was not efficient in differentiating açaí from juçara fruit samples. In contrast, LDA analysis permitted a correct differentiation between species with a predictive ability of 83.3%. The methodology that we have applied confirms that REE can be used to differentiate between açaí and juçara fruit samples and to identify their origin. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Jie; Institute of Power Source and Ecomaterials Science, Hebei University of Technology, Tianjin 300130; Meng, Junping, E-mail: srlj158@sina.com

2015-06-15

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

Fermi surface topology and hot spot distribution in the Kondo lattice system CeB 6

DOE PAGES

Neupane, Madhab; Alidoust, Nasser; Belopolski, Ilya; ...

2015-09-18

Rare-earth hexaborides have attracted considerable attention recently in connection to a variety of correlated phenomena including heavy fermions, superconductivity, and low-temperature magnetic phases. Here, we present high-resolution angle-resolved photoemission spectroscopy studies of trivalent CeB 6 and divalent BaB 6 rare-earth hexaborides. Here we find that the Fermi surface electronic structure of CeB 6 consists of large oval-shaped pockets around the X points of the Brillouin zone, whereas the states around the zone center Γ point are strongly renormalized. Our first-principles calculations agree with our experimental results around the X points but not around the Γ point, indicating areas of strongmore » renormalization located near Γ. The Ce quasiparticle states participate in the formation of hot spots at the Fermi surface, whereas the incoherent f states hybridize and lead to the emergence of dispersive features absent in the non-$f$ counterpart BaB 6. Lastly, our results provide an understanding of the electronic structure in rare-earth hexaborides, which will be useful in elucidating the nature of the exotic low-temperature phases in these materials.« less

Rare-earth element geochemistry and the origin of andesites and basalts of the Taupo Volcanic Zone, New Zealand

USGS Publications Warehouse

Cole, J.W.; Cashman, K.V.; Rankin, P.C.

1983-01-01

Two types of basalt (a high-Al basalt associated with the rhyolitic centres north of Taupo and a "low-Al" basalt erupted from Red Crater, Tongariro Volcanic Centre) and five types of andesite (labradorite andesite, labradorite-pyroxene andesite, hornblende andesite, pyroxene low-Si andesite and olivine andesite/low-Si andesite) occur in the Taupo Volcanic Zone (TVZ), North Island, New Zealand. Rare-earth abundances for both basalts and andesites are particularly enriched in light rare-earth elements. High-Al basalts are more enriched than the "low-Al" basalt and have values comparable to the andesites. Labradorite and labradorite-pyroxene andesites all have negative Eu anomalies and hornblende andesites all have negative Ce anomalies. The former is probably due to changing plagioclase composition during fractionation and the latter to late-stage hydration of the magma. Least-squares mixing models indicate that neither high-Al nor "low-Al" basalts are likely sources for labradorite/labradorite-pyroxene andesites. High-Al basalts are considered to result from fractionation of olivine and clinopyroxene from a garnet-free peridotite at the top of the mantle wedge. Labradorite/labradorite-pyroxene andesites are mainly associated with an older NW-trending arc. The source is likely to be garnet-free but it is not certain whether the andesites result from partial melting of the top of the subducting plate or a hydrated lower portion of the mantle wedge. Pyroxene low-Si andesites probably result from cumulation of pyroxene and calcic plagioclase within labradorite-pyroxene andesites, and hornblende andesites by late-stage hydration of labradorite-pyroxene andesite magma. Olivine andesites, low-Si andesites and "low-Al" basalts are related to the NNE-trending Taupo-Hikurangi arc structure. Although the initial source material is different for these lavas they have probably undergone a similar history to the labradorite/labradorite-pyroxene andesites. All lavas show evidence

Determination of rare earth elements concentration at different depth profile of Precambrian pegmatites using instrumental neutron activation analysis.

PubMed

Sadiq Aliyu, Abubakar; Musa, Yahaya; Liman, M S; Abba, Habu T; Chaanda, Mohammed S; Ngene, Nnamani C; Garba, N N

2018-01-01

The Keffi area hosts abundant pegmatite bodies as a result of the surrounding granitic intrusions. Keffi is part of areas that are geologically classified as North Central Basement Complex. Data on the mineralogy and mineralogical zonation of the Keffi pegmatite are scanty. Hence the need to understand the geology and mineralogical zonation of Keffi pegmatites especially at different depth profiles is relevant as a study of the elemental composition of the pegmatite is essential for the estimation of its economic viability. Here, the relative standardization method of instrumental neutron activation analysis (INAA) has been used to investigate the vertical deviations of the elemental concentrations of rare earth elements (REEs) at different depth profile of Keffi pegmatite. This study adopted the following metrics in investigating the vertical variations of REEs concentrations. Namely, the total contents of rare earth elements (∑REE); ratio of light to heavy rare earth elements (LREE/HREE), which defines the enrichment or depletion of REEs; europium anomaly (Eu/Sm); La/Lu ratio relative to chondritic meteorites. The study showed no significant variations in the total content of rare elements between the vertical depth profiles (100-250m). However, higher total concentrations of REEs (~ 92.65ppm) were recorded at the upper depth of the pegmatite and the europium anomaly was consistently negative at all the depth profiles suggesting that the Keffi pegmatite is enriched with light REEs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rare earth element concentrations in geological and synthetic samples using synchrotron X-ray fluorescence analysis

USGS Publications Warehouse

Chen, J.R.; Chao, E.C.T.; Back, J.M.; Minkin, J.A.; Rivers, M.L.; Sutton, S.R.; Cygan, G.L.; Grossman, J.N.; Reed, M.J.

1993-01-01

The concentrations of rare earth elements (REEs) in specific mineral grains from the Bayan Obo ore deposit and synthetic high-silica glass samples have been measured by synchrotron X-ray fluorescence (SXRF) analysis using excitation of the REE K lines between 33 and 63 keV. Because SXRF, a nondestructive analytical technique, has much lower minimum detection limits (MDLs) for REEs, it is an important device that extends the in situ analytical capability of electron probe microanalysis (EPMA). The distribution of trace amounts of REEs in common rock-forming minerals, as well as in REE minerals and minerals having minor quantities of REEs, can be analyzed with SXRF. Synchrotron radiation from a bending magnet and a wiggler source at the National Synchrotron Light Source, Brookhaven National Laboratory, was used to excite the REEs. MDLs of 6 ppm (La) to 26 ppm (Lu) for 3600 s in 60-??m-thick standard samples were obtained with a 25-??m diameter wiggler beam. The MDLs for the light REEs were a factor of 10-20 lower than the MDLs obtained with a bending magnet beam. The SXRF REE concentrations in mineral grains greater than 25 ??m compared favorably with measurements using EPMA. Because EPMA offered REE MDLs as low as several hundred ppm, the comparison was limited to the abundant light REEs (La, Ce, Pr, Nd). For trace values of medium and heavy REEs, the SXRF concentrations were in good agreement with measurements using instrumental neutron activation analysis (INAA), a bulk analysis technique. ?? 1993.

Chromatographic Techniques for Rare Earth Elements Analysis

NASA Astrophysics Data System (ADS)

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

2017-04-01

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

Geophysical Framework of a Rare Earth Element Enriched Terrane, Mountain Pass, California

NASA Astrophysics Data System (ADS)

Denton, K. M.; Ponce, D. A.; Peacock, J.; Miller, D. M.; Miller, J. S.

2016-12-01

Carbonatite ore deposits continue to be the primary source for rare earth elements (REEs), however large viable REE ore deposits are uncommon. The Mountain Pass carbonatite deposit, located in the eastern Mojave Desert of California, is the largest economic deposit of light REEs in North America. A 1.417 Ga ultrapotassic suite (shonkinite, syenite, and granite) and a 1.375 Ga barite-bastnasite-rich carbonatite (sovite) ore deposit comprise the enclave of REE-enriched outcrops and dikes that occupy a narrow ( 3 km) zone of 1.7 Ga gneiss extending at least 10-km to the southeast from southern Clark Mountain. Modeling of gravity, magnetic, and magnetotelluric (MT) data reveals subsurface features that form the structural framework of the REE terrane. The carbonatite and ultrapotassic mafic suite is associated with a local gravity high that is superimposed on a 4 km-wide gravity terrace, likely related to less dense granitic gneiss basement. Although physical property data indicate that the intrusive suite and carbonatite are essentially and nonmagnetic, aeromagnetic data indicate that these rocks occur along the eastern edge of a prominent north-northwest trending aeromagnetic high. This relationship suggests that they may have been preferentially emplaced along a zone of weakness or fault. The source of the magnetic high is 2-3 km below the surface and coincides with a relatively electrically conductive (3 orders of magnitude higher than surrounding rock) feature. MT data indicate that the western edge of the magnetic feature could be connected to a deeper ( 8 km) conductive feature related to possible intrusions and/or hydrothermal systems. The lack of a magnetic signature of the REE terrane can be explained by alteration of magnetite, given that the terrane lies within a broader alteration zone and observed magnetic low. If so, such an alteration event, capable of remobilizing rare earth elements, likely occurred during or after emplacement of the intrusive suite

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

DOE Data Explorer

Andrew Fowler

2015-07-24

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

Tunable emission in Ln3+ (Ce3+/Dy3+, Ce3+/Tb3+) doped KNa3Al4Si4O16 phosphor synthesized by combustion method

NASA Astrophysics Data System (ADS)

Kolte, M. M.; Pawade, V. B.; Bhattacharya, A. B.; Dhoble, S. J.

2018-05-01

Ln3+ (Ln = Ce3+/Dy3+, Ce3+/Tb3+) doped KNa3Al4Si4O16 phosphor has been synthesized by Combustion method (CS) at 550° C successfully. Ln3+ (Ln = Ce3+, Dy3+, Tb3+) ions when doped in KNa3Al4Si4O16 host lattice, it shows blue and green emission band under the near Ultraviolet (NUV) excitation wavelength. The Photoluminescence excitation (PLE) and emission spectra are observed due to f-f and d-f transition of rare earth ions. Also, an effective energy transfer (ET) study from Ce3+ → Dy3+ and Ce3+ → Tb3+ ions has been studied and confirmed on the basis of Dexter-Foster theory. Further synthesized phosphor is well characterized by XRD, SEM, TEM and decay time measurement. However, the analysis of crystallite size, lattice strain has been studied by using theoretical as well as experimental techniques. Hence, the observed tunable emission in Ln3+ doped KNa3Al4Si4O16 phosphor may be applicable for solid state lighting technology.

Mimicking the magnetic properties of rare earth elements using superatoms.

PubMed

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

2015-04-21

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

Rare earth element mineralogy, geochemistry, and preliminary resource assessment of the Khanneshin carbonatite complex, Helmand Province, Afghanistan

USGS Publications Warehouse

Tucker, Robert D.; Belkin, Harvey E.; Schulz, Klaus J.; Peters, Stephen G.; Buttleman, Kim P.

2011-01-01

There is increased concern about the future availability of rare earth elements (REE) because of China's dominance as the supplier of more than 95 percent of world REE output, their decision to restrict exports of rare earth products, and the rapid increase in world-wide consumption of rare earth product. As a result, countries such as the United States, Japan, and member nations of the European Union face a future of tight supplies and high prices for rare earth products unless other sources of REE are found and developed (Long and others, 2010; U.S. Geological Survey, 2011, p. 128-129, 184-185). We report and describe a significant new deposit of light rare earth elements (LREE), estimated at 1 Mt, within the Khanneshin carbonatite complex of south Afghanistan. The potential resource is located in a remote and rugged part of the igneous complex in a region previously identified by Soviet geologists in the 1970s. This report reviews the geologic setting of LREE deposit, presents new geochemical data documenting the grade of LREE mineralization, briefly describes the mineralogy and mineralogical associations of the deposit, and presents a preliminary estimate of LREE resources based on our current understanding of the geology.

Rationally designed mineralization for selective recovery of the rare earth elements

NASA Astrophysics Data System (ADS)

Hatanaka, Takaaki; Matsugami, Akimasa; Nonaka, Takamasa; Takagi, Hideki; Hayashi, Fumiaki; Tani, Takao; Ishida, Nobuhiro

2017-05-01

The increasing demand for rare earth (RE) elements in advanced materials for permanent magnets, rechargeable batteries, catalysts and lamp phosphors necessitates environmentally friendly approaches for their recovery and separation. Here, we propose a mineralization concept for direct extraction of RE ions with Lamp (lanthanide ion mineralization peptide). In aqueous solution containing various metal ions, Lamp promotes the generation of RE hydroxide species with which it binds to form hydrophobic complexes that accumulate spontaneously as insoluble precipitates, even under physiological conditions (pH ~6.0). This concept for stabilization of an insoluble lanthanide hydroxide complex with an artificial peptide also works in combination with stable scaffolds like synthetic macromolecules and proteins. Our strategy opens the possibility for selective separation of target metal elements from seawater and industrial wastewater under mild conditions without additional energy input.

Rationally designed mineralization for selective recovery of the rare earth elements.

PubMed

Hatanaka, Takaaki; Matsugami, Akimasa; Nonaka, Takamasa; Takagi, Hideki; Hayashi, Fumiaki; Tani, Takao; Ishida, Nobuhiro

2017-05-26

The increasing demand for rare earth (RE) elements in advanced materials for permanent magnets, rechargeable batteries, catalysts and lamp phosphors necessitates environmentally friendly approaches for their recovery and separation. Here, we propose a mineralization concept for direct extraction of RE ions with Lamp (lanthanide ion mineralization peptide). In aqueous solution containing various metal ions, Lamp promotes the generation of RE hydroxide species with which it binds to form hydrophobic complexes that accumulate spontaneously as insoluble precipitates, even under physiological conditions (pH ∼6.0). This concept for stabilization of an insoluble lanthanide hydroxide complex with an artificial peptide also works in combination with stable scaffolds like synthetic macromolecules and proteins. Our strategy opens the possibility for selective separation of target metal elements from seawater and industrial wastewater under mild conditions without additional energy input.

Rare earth elements (REE) and yttrium in stream waters, stream sediments, and Fe Mn oxyhydroxides: Fractionation, speciation, and controls over REE + Y patterns in the surface environment

NASA Astrophysics Data System (ADS)

Leybourne, Matthew I.; Johannesson, Karen H.

2008-12-01

We have collected ˜500 stream waters and associated bed-load sediments over an ˜400 km 2 region of Eastern Canada and analyzed these samples for Fe, Mn, and the rare earth elements (REE + Y). In addition to analyzing the stream sediments by total digestion (multi-acid dissolution with metaborate fusion), we also leached the sediments with 0.25 M hydroxylamine hydrochloride (in 0.05 M HCl), to determine the REE + Y associated with amorphous Fe- and Mn-oxyhydroxide phases. We are thus able to partition the REE into "dissolved" (<0.45 μm), labile (hydroxylamine) and detrital sediment fractions to investigate REE fractionation, and in particular, with respect to the development of Ce and Eu anomalies in oxygenated surface environments. Surface waters are typically LREE depleted ([La/Sm] NASC ranges from 0.16 to 5.84, average = 0.604, n = 410; where the REE are normalized to the North America Shale Composite), have strongly negative Ce anomalies ([Ce/Ce ∗] NASC ranges from 0.02 to 1.25, average = 0.277, n = 354), and commonly have positive Eu anomalies ([Eu/Eu ∗] NASC ranges from 0.295 to 1.77, average = 0.764, n = 84). In contrast, the total sediment have flatter REE + Y patterns relative to NASC ([La/Sm] NASC ranges from 0.352 to 1.12, average = 0.778, n = 451) and are slightly middle REE enriched ([Gd/Yb] NASC ranges from 0.55 to 3.75, average = 1.42). Most total sediments have negative Ce and Eu anomalies ([Ce/Ce ∗] NASC ranges from 0.097 to 2.12, average = 0.799 and [Eu/Eu ∗] NASC ranges from 0.39 to 1.43, average = 0.802). The partial extraction sediments are commonly less LREE depleted than the total sediments ([La/Sm] NASC ranges from 0.24 to 3.31, average = 0.901, n = 4537), more MREE enriched ([Gd/Yb] NASC ranges from 0.765 to 6.28, average = 1.97) and Ce and Eu anomalies (negative and positive) are more pronounced. The partial extraction recovered, on average ˜20% of the Fe in the total sediment, ˜80% of the Mn, and 21-29% of the REEs (Ce = 19

Realizing the therapeutic potential of rare earth elements in designing nanoparticles to target and treat glioblastoma.

PubMed

Lu, Victor M; McDonald, Kerrie L; Townley, Helen E

2017-10-01

The prognosis of brain cancer glioblastoma (GBM) is poor, and despite intense research, there have been no significant improvements within the last decade. This stasis implicates the need for more novel therapeutic investigation. One such option is the use of nanoparticles (NPs), which can be beneficial due to their ability to penetrate the brain, overcome the blood-brain barrier and take advantage of the enhanced permeation and retention effect of GBM to improve specificity. Rare earth elements possess a number of interesting natural properties due to their unique electronic configuration, which may prove therapeutically advantageous in an NP formulation. The underexplored exciting potential for rare earth elements to augment the therapeutic potential of NPs in GBM treatment is discussed in this review.

The Not-So-Rare Earths.

ERIC Educational Resources Information Center

Muecke, Gunter K.; Moller, Peter

1988-01-01

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

Modeling viscoelastic deformation of the earth due to surface loading by commercial finite element package - ABAQUS

NASA Astrophysics Data System (ADS)

Kit Wong, Ching; Wu, Patrick

2017-04-01

Wu (2004) developed a transformation scheme to model viscoelatic deformation due to glacial loading by commercial finite element package - ABAQUS. Benchmark tests confirmed that this method works extremely well on incompressible earth model. Bangtsson & Lund (2008),however, showed that the transformation scheme would lead to incorrect results if compressible material parameters are used. Their study implies that Wu's method of stress transformation is inadequate to model the load induced deformation of a compressible earth under the framework of ABAQUS. In light of this, numerical experiments are carried out to find if there exist other methods that serve this purpose. All the tested methods are not satisfying as the results failed to converge through iterations, except at the elastic limit. Those tested methods will be outlined and the results will be presented. Possible reasons of failure will also be discussed. Bängtsson, E., & Lund, B. (2008). A comparison between two solution techniques to solve the equations of glacially induced deformation of an elastic Earth. International journal for numerical methods in engineering, 75(4), 479-502. Wu, P. (2004). Using commercial finite element packages for the study of earth deformations, sea levels and the state of stress. Geophysical Journal International, 158(2), 401-408.

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

USDA-ARS?s Scientific Manuscript database

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

Raman scattering of rare earth hexaborides

NASA Astrophysics Data System (ADS)

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

2009-06-01

Raman scattering spectra were measured for the rare-earth hexaborides RB6 (R = Ce, Gd, or Dy). All Raman-active phonons due to B6 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.

Examining metallic glass formation in LaCe:Nb by ion implantation

DOE PAGES

Sisson, Richard; Reinhart, Cameron; Bridgman, Paul; ...

2017-01-01

In order to combine niobium (Nb) with lanthanum (La) and cerium (Ce), Nb ions were deposited within a thin film of these two elements. According to the Hume-Rothery rules, these elements cannot be combined into a traditional crystalline metallic solid. The creation of an amorphous metallic glass consisting of Nb, La, and Ce is then investigated. Amorphous metallic glasses are traditionally made using fast cooling of a solution of molten metals. In this paper, we show the results of an experiment carried out to form a metallic glass by implanting 9 MeV Nb 3+ atoms into a thin film ofmore » La and Ce. Prior to implantation, the ion volume distribution is calculated by Monte Carlo simulation using the SRIM tool suite. As a result, using multiple methods of electron microscopy and material characterization, small quantities of amorphous metallic glass are indeed identified.« less

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

EPA Science Inventory

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

Applying the Ce-in-zircon oxygen geobarometer to diverse silicic magmatic systems

NASA Astrophysics Data System (ADS)

Claiborne, L. L.; Miller, C. F.

2012-12-01

Zircon provides information on age, temperature, and composition of the magma from which it grew. In systems such as Mount St. Helens, where zircon is not coeval with the rest of the crystal cargo, it provides the only accessible record of the extended history of the magmatic system, including cycles of intrusion, crystallization and rejuvenation beneath an active volcano (Claiborne et al., 2010). The rare earth elements, which are present in measureable quantities in zircon, provide information about the composition of the magma from which zircon grew. Unique among the generally trivalent rare earth elements, cerium can exist as either trivalent or tetravalent, depending on the oxidation state of the magma. The tetravalent ion is highly compatible in zircon, in the site that usually hosts tetravalent zirconium, and so the amount of Cerium in zircon relative (relative to what would be expected of trivalent Ce) depends the oxidation state of the magma from which it grew. Trail et al. (2011) proposed a calibration based on experimental data that uses the Ce anomaly in zircon as a direct proxy for magma oxidation (fugacity), describing the relationship between Ce in zircon and magma oxygen fugacity as ln(Ce/Ce*)D = (0.1156±0.0050)xln(fO2)+(13860±708)/T-(6.125±0.484). For systems like Mount St. Helens, where the major minerals record only events in the hundreds to thousands of years leading to eruption, (including the Fe-Ti oxides traditionally relied upon for records of oxidation state of the magmas), this presents a novel approach for understanding more extended histories of oxidation of magmas in the tens and hundreds of thousands of years of magmatism at a volcanic center. This calibration also promises to help us better constrain conditions of crystallization in intrusive portions of volcanic systems, as well as plutonic bodes. We apply this new oxygen geobarometer to natural volcanic and plutonic zircons from a variety of tectonic settings, and compare to

Rare earth elements upon assessment of reasons of the geophagy in Sikhote-Alin region (Russian Federation), Africa and other world regions.

PubMed

Panichev, Alexander M; Popov, Vladimir K; Chekryzhov, Igor Yu; Seryodkin, Ivan V; Stolyarova, Tatiana A; Zakusin, Sergey V; Sergievich, Alexandr A; Khoroshikh, Pavel P

2016-12-01

Rocks eaten by wild animals on the Bolshoy Shanduyskiy kudur in the Sikhote-Alin region (Russian Federation) are zeolite-clay mineral complexes-products of weathering of zeolitized vitric tuffs of rhyolite composition, deposited in aqueous medium within the volcanic caldera of about 55 million years ago. By composition of rock-forming oxides, the tuffs refer to high-potassium calc-alkaline series. In trace elements of most favorite kudurites of the Bolshoy Shanduyskiy kudur, there are significantly increased contents of most of rare earth elements (2-5 times in comparison with surrounding rocks). The results of our analysis of geological and geochemical data on kudurs and kudurites in another part of the Sikhote-Alin, as well as on other regions of the world (particularly, in Africa and Indonesia), taking into account new data on the prevalence of rare earth elements in living matter and their medical and biological properties, enable us to consider the version of causal connection of the geophagy with rare earth elements.

Rare Earth Element Concentrations in Geothermal Wells at the Puna Geothermal Field, Hawaii

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fowler, Andrew; Zierenberg, Robert

Rare earth element concentrations in the geothermal wells at the Puna geothermal field, Hawaii. Samples taken from geothermal wells KS-5, KS-6W, KS-9W, KS-14E, and KS-16N. Includes pH and concentrations for Cerium, Dysprosium, Erbium, Europium, Gadolinium, Holmium, Lanthanum, Lutetium, Neodymium, Praseodymium, Samarium, Terbium, Thulium, Yttrium, and Ytterbium. Samples collected on November 11-17, 2016.

Rationally designed mineralization for selective recovery of the rare earth elements

PubMed Central

Hatanaka, Takaaki; Matsugami, Akimasa; Nonaka, Takamasa; Takagi, Hideki; Hayashi, Fumiaki; Tani, Takao; Ishida, Nobuhiro

2017-01-01

The increasing demand for rare earth (RE) elements in advanced materials for permanent magnets, rechargeable batteries, catalysts and lamp phosphors necessitates environmentally friendly approaches for their recovery and separation. Here, we propose a mineralization concept for direct extraction of RE ions with Lamp (lanthanide ion mineralization peptide). In aqueous solution containing various metal ions, Lamp promotes the generation of RE hydroxide species with which it binds to form hydrophobic complexes that accumulate spontaneously as insoluble precipitates, even under physiological conditions (pH ∼6.0). This concept for stabilization of an insoluble lanthanide hydroxide complex with an artificial peptide also works in combination with stable scaffolds like synthetic macromolecules and proteins. Our strategy opens the possibility for selective separation of target metal elements from seawater and industrial wastewater under mild conditions without additional energy input. PMID:28548098

Rare earth element abundances in rocks and minerals from the Fiskenaesset Complex, West Greenland. [comparison with lunar anorthosites

NASA Technical Reports Server (NTRS)

Henderson, P.; Fishlock, S. J.; Laul, J. C.; Cooper, T. D.; Conard, R. L.; Boynton, W. V.; Schmitt, R. A.

1976-01-01

The paper reports activation-analysis determinations of rare-earth-element (REE) and other trace-element concentrations in selected rocks, plagioclase, and mafic separates from the Fiskenaesset Complex. The REE abundances are found to be very low and atypical in comparison with other terrestrial anorthosites. The plagioclases are shown to be characterized by a deficiency in heavy RE elements relative to light ones and a positive Eu anomaly, while the mafic separates are enriched in heavy rare earths and have no Eu anomaly, except in one sample. It is found that the bulk and trace-element abundances of the plagioclases are similar to those observed in some lunar anorthosites, but the degree of Eu anomaly is less in the plagioclases. The data are taken as confirmation of the idea that fractionation processes were involved in the origin of the Complex, and it is concluded that the Complex may have been produced from a magma generated by partial melting of a garnet-bearing source.

Rare earth elements minimal harvest year variation facilitates robust geographical origin discrimination: The case of PDO "Fava Santorinis".

PubMed

Drivelos, Spiros A; Danezis, Georgios P; Haroutounian, Serkos A; Georgiou, Constantinos A

2016-12-15

This study examines the trace and rare earth elemental (REE) fingerprint variations of PDO (Protected Designation of Origin) "Fava Santorinis" over three consecutive harvesting years (2011-2013). Classification of samples in harvesting years was studied by performing discriminant analysis (DA), k nearest neighbours (κ-NN), partial least squares (PLS) analysis and probabilistic neural networks (PNN) using rare earth elements and trace metals determined using ICP-MS. DA performed better than κ-NN, producing 100% discrimination using trace elements and 79% using REEs. PLS was found to be superior to PNN, achieving 99% and 90% classification for trace and REEs, respectively, while PNN achieved 96% and 71% classification for trace and REEs, respectively. The information obtained using REEs did not enhance classification, indicating that REEs vary minimally per harvesting year, providing robust geographical origin discrimination. The results show that seasonal patterns can occur in the elemental composition of "Fava Santorinis", probably reflecting seasonality of climate. Copyright © 2016 Elsevier Ltd. All rights reserved.

Geochemistry of rare earth elements in Permian coals from the Huaibei Coalfield, China

USGS Publications Warehouse

Zheng, Lingyun; Liu, Gaisheng; Chou, C.-L.; Qi, C.; Zhang, Y.

2007-01-01

The rare earth elements (REEs) in coals are important because of: (a) REE patterns can be an indicator of the nature of source rocks of the mineral matter as well as sedimentary environments; (b) REEs abundance in coal may have industrial-significance. In this study, a total of thirty-four samples of Permian coal, partings, roof, and floor were collected from the Huaibei Coalfield, Anhui Province, China. Abundances of rare earth elements (REEs) and other elements in the samples were determined by inductively coupled-plasma mass spectrometry (ICP-MS) and inductively coupled-plasma atomic emission spectrometry (ICP-AES). The results show that the REEs are enriched in coals in the Huaibei Coalfield as compared with Chinese and U.S. coals and the world coal average. Coals in the Lower Shihezi Formation (No. 7, 5, and 4 Coals) and Upper Shihezi Formation (No. 3) have higher REE abundances than the coals in Shanxi Formation (No. 10). Magmatic intrusion resulted in high enrichment of REEs concentrations in No. 5 and 7 Coals. The REE abundances are positively correlated with the ash content. The mineral matter in these coals is mainly made up of clay minerals and carbonates. The REEs are positively correlated with lithophile elements including Si, Al, Ti, Fe, and Na, which are mainly distributed in clay minerals, indicating that REEs are contained mainly in clay minerals. The REE abundances in coals normalized by the ash are higher than that in partings. REEs abundances of coals cannot be accounted for by the REE content in the mineral matter, and some REEs associated with organic matter in coals. ?? 2007 Elsevier Ltd. All rights reserved.

Carbon footprint assessment of recycling technologies for rare earth elements: A case study of recycling yttrium and europium from phosphor.

PubMed

Hu, Allen H; Kuo, Chien-Hung; Huang, Lance H; Su, Chao-Chin

2017-02-01

Rare earth elements are key raw materials in high-technology industries. Mining activities and manufacturing processes of such industries have caused considerable environmental impacts, such as soil erosion, vegetation destruction, and various forms of pollution. Sustaining the long-term supply of rare earth elements is difficult because of the global shortage of rare earth resources. The diminishing supply of rare earth elements has attracted considerable concern because many industrialized countries regarded such elements as important strategic resources for economic growth. This study aims to explore the carbon footprints of yttrium and europium recovery techniques from phosphor. Two extraction recovery methods, namely, acid extraction and solvent extraction, were selected for the analysis and comparison of carbon footprints. The two following functional units were used: (1) the same phosphor amounts for specific Y and Eu recovery concentrations, and (2) the same phosphor amounts for extraction. For acid extraction method, two acidic solutions (H 2 SO 4 and HCl) were used at two different temperatures (60 and 90°C). For solvent extraction method, acid leaching was performed followed by ionic liquid extraction. Carbon footprints from acid and solvent extraction methods were estimated to be 10.1 and 10.6kgCO 2 eq, respectively. Comparison of the carbon emissions of the two extraction methods shows that the solvent extraction method has significantly higher extraction efficiency, even though acid extraction method has a lower carbon footprint. These results may be used to develop strategies for life cycle management of rare earth resources to realize sustainable usage. Copyright © 2016 Elsevier Ltd. All rights reserved.

Rare-earth-element minerals in martian breccia meteorites NWA 7034 and 7533: Implications for fluid-rock interaction in the martian crust

NASA Astrophysics Data System (ADS)

Liu, Yang; Ma, Chi; Beckett, John R.; Chen, Yang; Guan, Yunbin

2016-10-01

Paired martian breccia meteorites, Northwest Africa (NWA) 7034 and 7533, are the first martian rocks found to contain rare-earth-element (REE) phosphates and silicates. The most common occurrence is as clusters of anhedral monazite-(Ce) inclusions in apatite. Occasionally, zoned, irregular merrillite inclusions are also present in apatite. Monazite-bearing apatite is sometimes associated with alkali-feldspar and Fe-oxide. Apatite near merrillite and monazite generally contains more F and OH (F-rich region) than the main chlorapatite host and forms irregular boundaries with the main host. Locally, the composition of F-rich regions can reach pure fluorapatite. The chlorapatite hosts are similar in composition to isolated apatite without monazite inclusions, and to euhedral apatite in lithic clasts. The U-Th-total Pb ages of monazite in three apatite are 1.0 ± 0.4Ga (2σ), 1.1 ± 0.5Ga (2σ), and 2.8 ± 0.7Ga (2σ), confirming a martian origin. The texture and composition of monazite inclusions are mostly consistent with their formation by the dissolution of apatite and/or merrillite by fluid at elevated temperatures (>100 °C). In NWA 7034, we observed a monazite-chevkinite-perrierite-bearing benmoreite or trachyandesite clast. Anhedral monazite and chevkinite-perrierite grains occur in a matrix of sub-micrometer REE-phases and silicates inside the clast. Monazite-(Ce) and -(Nd) and chevkinite-perrierite-(Ce) and -(Nd) display unusual La and Ce depletion relative to Sm and Nd. In addition, one xenotime-(Y)-bearing pyrite-ilmenite-zircon clast with small amounts of feldspar and augite occurs in NWA 7034. One xenotime crystal was observed at the edge of an altered zircon grain, and a cluster of xenotime crystals resides in a mixture of alteration materials. Pyrite, ilmenite, and zircon in this clast are all highly altered, zircon being the most likely source of Y and HREE now present in xenotime. The association of xenotime with zircon, low U and Th contents, and the

Active earth pressure model tests versus finite element analysis

NASA Astrophysics Data System (ADS)

Pietrzak, Magdalena

2017-06-01

The purpose of the paper is to compare failure mechanisms observed in small scale model tests on granular sample in active state, and simulated by finite element method (FEM) using Plaxis 2D software. Small scale model tests were performed on rectangular granular sample retained by a rigid wall. Deformation of the sample resulted from simple wall translation in the direction `from the soil" (active earth pressure state. Simple Coulomb-Mohr model for soil can be helpful in interpreting experimental findings in case of granular materials. It was found that the general alignment of strain localization pattern (failure mechanism) may belong to macro scale features and be dominated by a test boundary conditions rather than the nature of the granular sample.

Effect of low doses of dietary rare earth elements on growth performance of broilers.

PubMed

He, M L; Wehr, U; Rambeck, W A

2010-02-01

The present study was designed to investigate effect of dietary rare earth elements (REE), including both organic and inorganic compounds, on growth performance of broilers. In experiment 1, a total of 180 male Ross broiler chicks were allocated to 72 pens with different assignment: four chicks per pen or individually. The following three treatment diets were applied: control, REE-chlorides at a dose of 40 mg/kg and REE-citrate at a dose of 70 mg/kg. Each treatment group had 24 pens containing both assignments (12 pens each). In experiment 2, a total of 72 male 3-day-old Ross broiler chicks were separated to four groups: control, REE-chlorides at a dose of 70 mg/kg and REE-citrate at doses of 70 mg/kg and 100 mg/kg. In experiment 1, dietary REE-citrate improved body weight gain during the overall period by 5.0% (p < 0.05) while the increase with REE-chloride was not significant. In experiment 2, growth effects (p < 0.05) were only found in the period from day 21 to slaughter with all REE forms, and feed conversion ratio was improved by 3.4% (p < 0.05) with REE-citrate. No significant effects of REE were found on chill weight, percentages of breast meat, thigh weight, drumstick weight and wing weight. Concentrations of La and Ce in the liver and muscles were very low, accounting for 0.11-0.76 and 0.02-0.30 mg/kg respectively. There was weak tendency for a dose-response relationship especially in the groups supplemented with REE-chlorides. The main blood serum biochemical parameters were not significantly affected by REE in the diets. The results suggest that dietary supplementation of low doses of REE-citrates might improve growth performance of broilers without affecting carcass composition and health of the broilers.

Recovery and separation of rare earth elements using columns loaded with DNA-filter hybrid.

PubMed

Takahashi, Yoshio; Kondo, Kazuhiro; Miyaji, Asami; Umeo, Miyuki; Honma, Tetsuo; Asaoka, Satoshi

2012-01-01

Given that the supply of several rare earth elements (REEs) is sometimes limited, recycling REEs used in various advanced materials, such as Nd magnets, is important for realizing efficient use of REE resources. In the present work, the feasibility of using DNA for REE recovery and separation was examined, along with the identification of the binding site of REEs in DNA. In particular, a DNA-cellulose filter paper hybrid was prepared so that DNA-based materials can be used for the separation of REEs using columns loaded with DNA. N,N'-Disuccinimidyl was used as a cross-linker reagent for the fixation of DNA onto a fibrous cellulose filter. The results showed that (i) the DNA-filter hybrid has a sufficiently high affinity to adsorb REEs; (ii) the adsorption capacity was 0.182 mg/g for Nd; and (iii) the affinity of REEs for DNA was stronger for REEs with larger atomic numbers. The difference of the affinity among REEs in the third result was compared with the adsorption patterns of REEs discussed in the literature. The comparison suggests that phosphate in the DNA-filter paper hybrid was responsible for REE adsorption onto the hybrid. The results were supported by the Nd, Dy, and Lu L(III)-edge EXAFS; the REE-P shell was identified for the second neighboring atom, showing the importance of the phosphate site as REE binding sites. The difference in the affinity among REEs suggest that group separation of REEs (such as La, Ce, (Pr and Nd), (Ho, Dy, and Er), (Tb and Gd), (Sm, Eu), Tm, Yb, and Lu) is possible, although complete isolation of each REE from a solution containing all REEs may be difficult. For practical applications, Nd and Fe(III) were successfully separated from a synthetic solution of Nd magnet waste using columns loaded with the DNA-filter hybrid.

New reversed phase-high performance liquid chromatographic method for selective separation of yttrium from all rare earth elements employing nitrilotriacetate complexes in anion exchange mode.

PubMed

Dybczyński, Rajmund S; Kulisa, Krzysztof; Pyszynska, Marta; Bojanowska-Czajka, Anna

2015-03-20

Separation of Y from other rare earth elements (REE) is difficult because of similarity of its ionic radius to ionic radii of Tb, Dy and Ho. In the new RP-HPLC system with C18 column, tetra-n-butyl ammonium hydroxide (TBAOH) as an ion interaction reagent (IIR), nitrilotriacetic acid (NTA) as a complexing agent at pH=2.8-3.5, and post column derivatization with Arsenazo III, yttrium is eluted in the region of light REE, between Nd and Sm and is base line separated from Nd and Sm and even from promethium. Simple model employing literature data on complex formation of REE with NTA and based on anion exchange mechanism was developed to foresee the order of elution of individual REE. The model correctly predicted that lanthanides up to Tb will be eluted in the order of increasing Atomic Number (At.No.) but all heavier REE will show smaller retention factors than Tb. Concurrent UV/VIS detection at 658nm and the use of radioactive tracers together with γ-ray spectrometric measurements made possible to establish an unique elution order of elution of REE: La, Ce, Pr, Nd, Pm, Y, Sm, Er, Ho, Tm, Yb, Eu, Lu, Dy+Gd, Tb, Sc. The real place of Y however, in this elution series differs from that predicted by the model (Y between Sm and Eu). The method described in this work enables selective separation of Y from La, Ce, Pr, Nd, Pm, Sm and all heavier REE treated as a group. Copyright © 2015 Elsevier B.V. All rights reserved.

Novel hydrogen decrepitation behaviors of (La, Ce)-Fe-B strips

NASA Astrophysics Data System (ADS)

Jin, Jiaying; Bai, Guohua; Zhang, Yujing; Peng, Baixing; Liu, Yongsheng; Ma, Tianyu; Yan, Mi

2018-05-01

La and Ce substitution for Nd in the 2:14:1-type sintered magnet is of commercial interest to reduce the material cost and to balance the utilization of rare earth (RE) sources. As hydrogen decrepitation (HD) is widely utilized to prepare the magnetic powders during magnets fabrication, incorporating La and Ce into the Nd-Fe-B permanent magnets, however, may exert complex influences on the decrepitation behavior. In the present work, through a comparative study of the HD behaviors between the (La, Ce)-Fe-B strips and the conventional Nd-Fe-B ones, we find that similar to the Nd-Fe-B system, increasing hydrogen pressures from 2.5 to 5.5 MPa do not break the 2:14:1 tetragonal structure of (La, Ce)-Fe-B strips. The enhanced hydrogen absorption behaviors are observed with increasing pressure, which are still inferior to that of the Nd-Fe-B strips. This should be ascribed to the higher oxygen affinity of La and Ce than that of Nd, leading to the decreased amount of active RE-rich phase and limited hydrogen diffusion channel. As a result, the hydrogen absorption of 2:14:1 matrix phase is significantly suppressed, dramatically weakening the exothermic effect. This finding suggests that La and Ce with stable 2:14:1 tetragonal structure upon HD process are promising alternatives for Nd, despite that more precise oxygen control is necessary for the microstructure modification and magnetic performance enhancement of (La, Ce)-Fe-B sintered magnets.

High contents of rare earth elements (REEs) in stream waters of a Cu-Pb-Zn mining area.

PubMed

Protano, G; Riccobono, F

2002-01-01

Stream waters draining an old mining area present very high rare earth element (REE) contents, reaching 928 microg/l as the maximum total value (sigmaREE). The middle rare earth elements (MREEs) are usually enriched with respect to both the light (LREEs) and heavy (HREEs) elements of this group, producing a characteristic "roof-shaped" pattern of the shale Post-Archean Australian Shales-normalized concentrations. At the Fenice Capanne Mine (FCM), the most important base metal mine of the study area, the REE source coincides with the mine tailings, mostly the oldest ones composed of iron-rich materials. The geochemical history of the REEs released into Noni stream from wastes in the FCM area is strictly determined by the pH, which controls the REE speciation and in-stream processes. The formation of Al-rich and mainly Fe-rich flocs effectively scavenges the REEs, which are readily and drastically removed from the solution when the pH approaches neutrality. Leaching experiments performed on flocs and waste materials demonstrate that Fe-oxides/oxyhydroxides play a key role in the release of lanthanide elements into stream waters. The origin of the "roof-shaped" REE distribution pattern as well as the peculiar geochemical behavior of some lanthanide elements in the aqueous system are discussed.

Rare earth element and uranium-thorium variations in tufa deposits from the Mono Basin, CA

NASA Astrophysics Data System (ADS)

Wilcox, E. S.; Tomascak, P. B.; Hemming, N.; Hemming, S. R.; Rasbury, T.; Stine, S.; Zimmerman, S. R.

2009-12-01

Samples of fossil tufa deposits from several localities in the Mono Basin, eastern California, were analyzed for trace element concentrations in order to better understand changes in lake composition in the past. These deposits were formed during the last glacial cycle, mostly during deglaciation (Benson et al., 1990, PPP). Three elevations are represented by the analyses. Samples from near Highway 167 were sampled between 2063 and 2069 m asl. Samples from near Thompson Road were sampled between 2015 and 2021 m. One layered mound was sampled at 1955 m. Concentrations of the lanthanide rare earth elements (REE), in particular the heavy/light (HREE/LREE) distributions, have been shown to be sensitive to alkalinity in modern saline lakes (e.g., Johannesson et al., 1994, GRL, 21, 773-776), and the same has been suggested for U/Th (Anderson et al., 1982, Science, 216, 514-516). Holocene to near-modern tufa towers exist in shallow water and around the current shoreline (1945 m). Tufa towers above 2000 m include a characteristic morphology termed thinolite, interpreted to represent pseudomorphs after the very cold water mineral ikaite. Most lower elevation towers do not have the thinolite morphology, but some layered tufa mounds at low elevations include several layers of thinolite, such as the one sampled for this project. Analyses were made on millimeter-scale bulk samples from tufa towers. Measurements were made on sample solutions with a Varian 820MS quadrupole ICP-MS. Mono Basin tufa samples have total REE concentrations ranging from 0.029 to 0.77 times average shales. Samples have flat to moderately HREE-enriched shale-normalized patterns with limited overall variability ([La/Lu]SN of 1.8 to 9.6) but with some variability in the slope of the HREE portion of the patterns. Tufa towers sampled from three elevations have (Gd/Lu)SN of 0.40 to 1.5. The REE patterns of most samples have small positive Ce anomalies, but a minority of samples, all from the layered tufa mound

Contributing opportunistic resources to the grid with HTCondor-CE-Bosco

NASA Astrophysics Data System (ADS)

Weitzel, Derek; Bockelman, Brian

2017-10-01

The HTCondor-CE [1] is the primary Compute Element (CE) software for the Open Science Grid. While it offers many advantages for large sites, for smaller, WLCG Tier-3 sites or opportunistic clusters, it can be a difficult task to install, configure, and maintain the HTCondor-CE. Installing a CE typically involves understanding several pieces of software, installing hundreds of packages on a dedicated node, updating several configuration files, and implementing grid authentication mechanisms. On the other hand, accessing remote clusters from personal computers has been dramatically improved with Bosco: site admins only need to setup SSH public key authentication and appropriate accounts on a login host. In this paper, we take a new approach with the HTCondor-CE-Bosco, a CE which combines the flexibility and reliability of the HTCondor-CE with the easy-to-install Bosco. The administrators of the opportunistic resource are not required to install any software: only SSH access and a user account are required from the host site. The OSG can then run the grid-specific portions from a central location. This provides a new, more centralized, model for running grid services, which complements the traditional distributed model. We will show the architecture of a HTCondor-CE-Bosco enabled site, as well as feedback from multiple sites that have deployed it.

Determination of Anand parameters for SnAgCuCe solder

NASA Astrophysics Data System (ADS)

Zhang, Liang; Xue, Songbai; Gao, Lili; Zeng, Guang; Sheng, Zhong; Chen, Yan; Yu, Shenglin

2009-10-01

A unified viscoplastic constitutive model, Anand equations, was used to represent the inelastic deformation behavior for Sn3.8Ag0.7Cu/Sn3.8Ag0.7 Cu0.03Ce solders in surface mount technology. The Anand parameters of the constitutive equations for the SnAgCu and SnAgCuCe solders were determined from separated constitutive relations and experimental results. Non-linear least-squares fitting was selected to determine the model constants. Comparisons were then made with experimental measurements of the stress-inelastic strain curves: excellent agreement was found. The model accurately predicted the overall trend of steady-state stress-strain behavior of SnAgCu and SnAgCuCe solders for the temperature ranges from -55 to 125 °C and for the strain rate range from 1% s-1 to 0.01% s-1. It is concluded that the Anand model can be applied to represent the inelastic deformation behavior of solders at high homologous temperatures and can be recommended for finite element simulation of the stress-strain response of lead-free soldered joints. Based on the Anand model, the investigations of thermo-mechanical behavior of SnAgCu and SnAgCuCe soldered joints in fine pitch quad flat package by the finite element code have been done under thermal cyclic loading, and it is found that the reliability of the SnAgCuCe soldered joints is better than that of the SnAgCu soldered joints.

2Flux growth and characterization of Ce-substituted Nd 2 Fe 14 B single crystals

DOE PAGES

Susner, Michael A.; Conner, Benjamin S.; Saparov, Bayrammurad I.; ...

2016-10-27

Single crystals of (Nd 1-xCe x) 2Fe 14B are grown out of Fe-(Nd,Ce) flux. Chemical and structural analysis of the crystals indicate that (Nd 1-xCe x) 2Fe 14B forms a solid solution until at least x = 0.38 with a Vegard-like variation of the lattice constants with x. Refinements of single crystal neutron diffraction data indicate that Ce has a slight site preference (7:3) for the 4g rare earth site over the 4f site. Magnetization measurements at 300 K show only small decreases with increasing Ce content in saturation magnetization (M s) and anisotropy field (H A), and Curie temperaturemore » (T C). First principles calculations are carried out to understand the effect of Ce substitution on the electronic and magnetic properties. For a multitude of applications, it is expected that the advantage of incorporating lower-cost and more abundant Ce will outweigh the small adverse effects on magnetic properties. In conclusion, Ce-substituted Nd 2Fe 14B is therefore a potential high-performance permanent magnet material with substantially reduced Nd content.« less

Template-Free Hydrothermal Synthesis, Mechanism, and Photocatalytic Properties of Core-Shell CeO2 Nanospheres

NASA Astrophysics Data System (ADS)

Li, Huijie; Meng, Fanming; Gong, Jinfeng; Fan, Zhenghua; Qin, Rui

2018-03-01

CeO2 nanospheres with the core-shell nanostructure have been successfully synthesized by a template-free hydrothermal method. The structures, morphologies and optical properties of core-shell CeO2 nanospheres were analyzed by X-ray diffraction (XRD), TG, Fourier transform infrared spectroscopy, XRD, EDS, SAED, scanning electron microscopy and transmission electron microscopy, UV-Vis diffuse reflectance spectra, Raman analyses. The degradation efficiencies of core-shell CeO2 nanospheres for methyl orange were as high as 93.49, 95.67 and 98.28% within 160 min, and the rates of photo degradation of methyl orange by core-shell CeO2 nanospheres under UV-light were 0.01693, 0.01782 and 0.02375 min-1. Methyl orange was degraded in photocatalytic oxidation processes, which mainly gave the credit to a large number of reactive species including h+, surface superoxide species ·O2 -, and ·OH radicals. The core-shell structure, small crystallite size and the conversion between Ce3+ and Ce4+ of CeO2 nanospheres were of importance for its catalytic activity. These results demonstrated the possibility of improving the efficient catalysts of the earth abundant CeO2 catalysts.

Electronic structure of R Sb ( R = Y , Ce, Gd, Dy, Ho, Tm, Lu) studied by angle-resolved photoemission spectroscopy

DOE PAGES

Wu, Yun; Lee, Yongbin; Kong, Tai; ...

2017-07-15

Here, we use high-resolution angle-resolved photoemission spectroscopy (ARPES) and electronic structure calculations to study the electronic properties of rare-earth monoantimonides RSb (R = Y, Ce, Gd, Dy, Ho, Tm, Lu). The experimentally measured Fermi surface (FS) of RSb consists of at least two concentric hole pockets at the Γ point and two intersecting electron pockets at the X point. These data agree relatively well with the electronic structure calculations. Detailed photon energy dependence measurements using both synchrotron and laser ARPES systems indicate that there is at least one Fermi surface sheet with strong three-dimensionality centered at the Γ point. Duemore » to the “lanthanide contraction”, the unit cell of different rare-earth monoantimonides shrinks when changing the rare-earth ion from CeSb to LuSb. This results in the differences in the chemical potentials in these compounds, which are demonstrated by both ARPES measurements and electronic structure calculations. Interestingly, in CeSb, the intersecting electron pockets at the X point seem to be touching the valence bands, forming a fourfold-degenerate Dirac-like feature. On the other hand, the remaining rare-earth monoantimonides show significant gaps between the upper and lower bands at the X point. Furthermore, similar to the previously reported results of LaBi, a Dirac-like structure was observed at the Γ point in YSb, CeSb, and GdSb, compounds showing relatively high magnetoresistance. This Dirac-like structure may contribute to the unusually large magnetoresistance in these compounds.« less

Electronic structure of R Sb ( R = Y , Ce, Gd, Dy, Ho, Tm, Lu) studied by angle-resolved photoemission spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Yun; Lee, Yongbin; Kong, Tai

Here, we use high-resolution angle-resolved photoemission spectroscopy (ARPES) and electronic structure calculations to study the electronic properties of rare-earth monoantimonides RSb (R = Y, Ce, Gd, Dy, Ho, Tm, Lu). The experimentally measured Fermi surface (FS) of RSb consists of at least two concentric hole pockets at the Γ point and two intersecting electron pockets at the X point. These data agree relatively well with the electronic structure calculations. Detailed photon energy dependence measurements using both synchrotron and laser ARPES systems indicate that there is at least one Fermi surface sheet with strong three-dimensionality centered at the Γ point. Duemore » to the “lanthanide contraction”, the unit cell of different rare-earth monoantimonides shrinks when changing the rare-earth ion from CeSb to LuSb. This results in the differences in the chemical potentials in these compounds, which are demonstrated by both ARPES measurements and electronic structure calculations. Interestingly, in CeSb, the intersecting electron pockets at the X point seem to be touching the valence bands, forming a fourfold-degenerate Dirac-like feature. On the other hand, the remaining rare-earth monoantimonides show significant gaps between the upper and lower bands at the X point. Furthermore, similar to the previously reported results of LaBi, a Dirac-like structure was observed at the Γ point in YSb, CeSb, and GdSb, compounds showing relatively high magnetoresistance. This Dirac-like structure may contribute to the unusually large magnetoresistance in these compounds.« less

Germanium and Rare Earth Element accumulation in woody bioenergy crops

NASA Astrophysics Data System (ADS)

Hentschel, Werner

2016-04-01

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

Geology and market-dependent significance of rare earth element resources

NASA Astrophysics Data System (ADS)

Simandl, G. J.

2014-12-01

China started to produce rare earth elements (REEs) in the 1980s, and since the mid-1990s, it has become the dominant producer. Rare earth element export quotas first introduced by the Chinese government in the early 2000s were severely reduced in 2010 and 2011. This led to strong government-created disparity between prices within China and the rest of the world. Industrialized countries identified several REEs as strategic metals. Because of rapid price increases of REE outside of China, we have witnessed a world-scale REE exploration rush. The REE resources are concentrated in carbonatite-related deposits, peralkaline igneous rocks, pegmatites, monazite ± apatite veins, ion adsorption clays, placers, and some deep ocean sediments. REE could also be derived as a by-product of phosphate fertilizer production, U processing, mining of Ti-Zr-bearing placers, and exploitation of Olympic Dam subtype iron oxide copper gold (IOCG) deposits. Currently, REEs are produced mostly from carbonatite-related deposits, but ion adsorption clay deposits are an important source of heavy REE (HREE). Small quantities of REE are derived from placer deposits and one peralkaline intrusion-related deposit. The ideal REE development targets would be located in a politically stable jurisdiction with a pro-mining disposition such as Canada and Australia. REE grade, HREE/light REE (LREE) ratio of the mineralization, tonnage, mineralogy, and permissive metallurgy are some of the key technical factors that could be used to screen potential development projects. As REEs are considered strategic metals from economic, national security, and environmental points of view, technical and economic parameters alone are unlikely to be used in REE project development decision-making. Recycling of REE is in its infancy and unless legislated, in the short term, it is not expected to contribute significantly to the supply of REE.

Bioleaching of rare earth elements from waste phosphors and cracking catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reed, David W.; Fujita, Yoshiko; Daubaras, Dayna L.

Four microbial cultures were evaluated for organic acid production and their potential utility for leaching of rare earth elements (REE) from retorted phosphor powder (RPP) and spent fluidized cracking catalyst (FCC). Three of the cultures (2 bacterial, 1 fungal) were isolated from environmental and industrial materials known to contain rare earth elements. The other was the well-known and industrially important bacterium Gluconobacter oxydans. Gluconic acid was the predominant identified organic acid produced by all of the cultures; citric and acetic acid were among the other acids detected. There was also maximum REE leaching by cell free culture supernatants obtained withmore » Gluconobacter and the FCC; 49% of total REE was recovered, with preferential recovery of lanthanum over cerium. The phosphor powder was more difficult to leach; only ~2 % total REE was leached from RPP with Gluconobacter. Tests with the RPP indicated that the extent of REE solubilization was similar whether whole cell cultures or cell-free supernatants were used. However, Gluconobacter cell-free culture supernatants with 10-15 mM gluconic acid outperformed abiotically prepared leaching solutions with 30 mM gluconic acid concentrations. Abiotic tests showed that increasing gluconic acid concentrations increased leaching efficiency; for example, total REE leaching from FCC increased from 24 to 36 to 45% when gluconic acid was increased from 10 to 30 to 90 mM. Our research shows that utilizing microorganisms that produce gluconic acid can result in effective leaching of REE from waste materials, and optimizing gluconic acid production will improve recovery.« less

Bioleaching of rare earth elements from waste phosphors and cracking catalysts

DOE PAGES

Reed, David W.; Fujita, Yoshiko; Daubaras, Dayna L.; ...

2016-08-22

Four microbial cultures were evaluated for organic acid production and their potential utility for leaching of rare earth elements (REE) from retorted phosphor powder (RPP) and spent fluidized cracking catalyst (FCC). Three of the cultures (2 bacterial, 1 fungal) were isolated from environmental and industrial materials known to contain rare earth elements. The other was the well-known and industrially important bacterium Gluconobacter oxydans. Gluconic acid was the predominant identified organic acid produced by all of the cultures; citric and acetic acid were among the other acids detected. There was also maximum REE leaching by cell free culture supernatants obtained withmore » Gluconobacter and the FCC; 49% of total REE was recovered, with preferential recovery of lanthanum over cerium. The phosphor powder was more difficult to leach; only ~2 % total REE was leached from RPP with Gluconobacter. Tests with the RPP indicated that the extent of REE solubilization was similar whether whole cell cultures or cell-free supernatants were used. However, Gluconobacter cell-free culture supernatants with 10-15 mM gluconic acid outperformed abiotically prepared leaching solutions with 30 mM gluconic acid concentrations. Abiotic tests showed that increasing gluconic acid concentrations increased leaching efficiency; for example, total REE leaching from FCC increased from 24 to 36 to 45% when gluconic acid was increased from 10 to 30 to 90 mM. Our research shows that utilizing microorganisms that produce gluconic acid can result in effective leaching of REE from waste materials, and optimizing gluconic acid production will improve recovery.« less

Interactions of phosphate solubilising microorganisms with natural rare-earth phosphate minerals: a study utilizing Western Australian monazite.

PubMed

Corbett, Melissa K; Eksteen, Jacques J; Niu, Xi-Zhi; Croue, Jean-Philippe; Watkin, Elizabeth L J

2017-06-01

Many microbial species are capable of solubilising insoluble forms of phosphate and are used in agriculture to improve plant growth. In this study, we apply the use of known phosphate solubilising microbes (PSM) to the release of rare-earth elements (REE) from the rare-earth phosphate mineral, monazite. Two sources of monazite were used, a weathered monazite and mineral sand monazite, both from Western Australia. When incubated with PSM, the REE were preferentially released into the leachate. Penicillum sp. released a total concentration of 12.32 mg L -1 rare-earth elements (Ce, La, Nd, and Pr) from the weathered monazite after 192 h with little release of thorium and iron into solution. However, cultivation on the mineral sands monazite resulted in the preferential release of Fe and Th. Analysis of the leachate detected the production of numerous low-molecular weight organic acids. Gluconic acid was produced by all microorganisms; however, other organic acids produced differed between microbes and the monazite source provided. Abiotic leaching with equivalent combinations of organic acids resulted in the lower release of REE implying that other microbial processes are playing a role in solubilisation of the monazite ore. This study demonstrates that microbial solubilisation of monazite is promising; however, the extent of the reaction is highly dependent on the monazite matrix structure and elemental composition.

Partitioning of light lithophile elements during basalt eruptions on Earth and application to Martian shergottites

NASA Astrophysics Data System (ADS)

Edmonds, Marie

2015-02-01

An enigmatic record of light lithophile element (LLE) zoning in pyroxenes in basaltic shergottite meteorites, whereby LLE concentrations decrease dramatically from the cores to the rims, has been interpreted as being due to partitioning of LLE into a hydrous vapor during magma ascent to the surface on Mars. These trends are used as evidence that Martian basaltic melts are water-rich (McSween et al., 2001). Lithium and boron are light lithophile elements (LLE) that partition into volcanic minerals and into vapor from silicate melts, making them potential tracers of degassing processes during magma ascent to the surface of Earth and of other planets. While LLE degassing behavior is relatively well understood for silica-rich melts, where water and LLE concentrations are relatively high, very little data exists for LLE abundance, heterogeneity and degassing in basaltic melts. The lack of data hampers interpretation of the trends in the shergottite meteorites. Through a geochemical study of LLE, volatile and trace elements in olivine-hosted melt inclusions from Kilauea Volcano, Hawaii, it can be demonstrated that lithium behaves similarly to the light to middle rare Earth elements during melting, magma mixing and fractionation. Considerable heterogeneity in lithium and boron is inherited from mantle-derived primary melts, which is dominant over the fractionation and degassing signal. Lithium and boron are only very weakly volatile in basaltic melt erupted from Kilauea Volcano, with vapor-melt partition coefficients <0.1. Degassing of LLE is further inhibited at high temperatures. Pyroxene and associated melt inclusion LLE concentrations from a range of volcanoes are used to quantify lithium pyroxene-melt partition coefficients, which correlate negatively with melt H2O content, ranging from 0.13 at low water contents to <0.08 at H2O contents >4 wt%. The observed terrestrial LLE partitioning behavior is extrapolated to Martian primitive melts through modeling. The zoning

High-resolution structural characterization and magnetic properties of epitaxial Ce-doped yttrium iron garnet thin films

NASA Astrophysics Data System (ADS)

Li, Zhong; Vikram Singh, Amit; Rastogi, Ankur; Gazquez, Jaume; Borisevich, Albina Y.; Mishra, Rohan; Gupta, Arunava

2017-07-01

Thin films of magnetic garnet materials, e.g. yttrium iron garnet (Y3Fe5O12, YIG), are useful for a variety of applications including microwave integrated circuits and spintronics. Substitution of rare earth ions, such as cerium, is known to enhance the magneto-optic Kerr effect (MOKE) as compared to pure YIG. Thin films of Ce0.75Y2.25Fe5O12 (Ce:YIG) have been grown using the pulsed laser deposition (PLD) technique and their crystal structure examined using high resolution scanning transmission electron microscopy. Homogeneous substitution of Ce in YIG, without oxidation to form a separate CeO2 phase, can be realized in a narrow process window with resulting enhancement of the MOKE signal. The thermally generated signal due to spin Seebeck effect for the optimally doped Ce:YIG films has also been investigated.

Oxidative mobilization of cerium and uranium and enhanced release of "immobile" high field strength elements from igneous rocks in the presence of the biogenic siderophore desferrioxamine B

NASA Astrophysics Data System (ADS)

Kraemer, Dennis; Kopf, Sebastian; Bau, Michael

2015-09-01

Polyvalent trace elements such as the high field strength elements (HFSE) are commonly considered rather immobile during low-temperature water-rock interaction. Hence, they have become diagnostic tools that are widely applied in geochemical studies. We present results of batch leaching experiments focused on the mobilization of certain HFSE (Y, Zr, Hf, Th, U and rare earth elements) from mafic, intermediate and felsic igneous rocks in the presence and absence, respectively, of the siderophore desferrioxamine B (DFOB). Our data show that DFOB strongly enhances the mobility of these trace elements during low-temperature water-rock interaction. The presence of DFOB produces two distinct features in the Rare Earths and Yttrium (REY) patterns of leaching solutions, regardless of the mineralogical and chemical composition or the texture of the rock type studied. Bulk rock-normalized REY patterns of leaching solutions with DFOB show (i) a very distinct positive Ce anomaly and (ii) depletion of La and other light REY relative to the middle REY, with a concave downward pattern between La and Sm. These features are not observed in experiments with hydrochloric acid, acetic acid or deionized water. In DFOB-bearing leaching solutions Ce and U are decoupled from and selectively enriched relative to light REY and Th, respectively, due to oxidation to Ce(IV) and U(VI). Oxidation of Ce3+ and U4+ is promoted by the significantly higher stability of the Ce(IV) and U(VI) DFOB complexes as compared to the Ce(III) and U(IV) DFOB complexes. This is similar to the relationship between the Ce(IV)- and Ce(III)-pentacarbonate complexes that cause positive Ce anomalies in alkaline lakes. However, while formation of Ce(IV) carbonate complexes is confined to alkaline environments, Ce(IV) DFOB complexes may produce positive Ce anomalies even in mildly acidic and near-neutral natural waters. Siderophore-promoted dissolution processes also significantly enhance mobility of other 'immobile' HFSE

The impact of transport processes on rare earth element patterns in marine authigenic and biogenic phosphates

NASA Astrophysics Data System (ADS)

Auer, Gerald; Reuter, Markus; Hauzenberger, Christoph A.; Piller, Werner E.

2017-04-01

Rare earth elements (REEs) are commonly used proxies to reconstruct water chemistry and oxygen saturation during the formation of authigenic and biogenic phosphates in marine environments. In the modern ocean REEs exhibit a distinct pattern with enrichment of heavy REEs and strong depletion in cerium (Ce). The wide range of REE enrichment patterns found in ancient marine phosphates lead to the proposition that water chemistry has been very different in the Earth's past. However, both early and late diagenesis are known to affect REE signatures in phosphates altering primary marine signals. Herein we present a dataset of REE signatures in 38 grain specific LA-ICP-MS measurements of isolated phosphate and carbonate grains in three discrete rock samples. The phosphates mainly consist of authigenic phosphates and phosphatized microfossils that formed in a microbially mediated micro-milieu. In addition, isolated biogenic and reworked phosphatic grains are also present. The phosphates are emplaced in bioclastic grain- to packstones deposited on a carbonate ramp setting in the central Mediterranean Sea during the middle Miocene Monterey event. The results reveal markedly different REE patterns (normalized to the Post Archean Australian Shale standard) in terms of total enrichment and pattern shape. Analyses of REE diagenesis proxies show that diagenetic alteration affected the samples only to a minor degree. Grain shape and REE patterns together indicate that authigenic, biogenic and reworked phosphates have distinct REE patterns irrespective of the sample. Our study shows that while REE patterns in phosphates do reflect water chemistry during authigenesis, they are often already heavily altered during reworking, a process, which can occur in geologically negligible timespans. REE patterns are therefore more likely to reflect complex enrichment processes after their formation. Similarities in the REE patterns of reworked and biogenic phosphate further suggest that the

Origin of Volatiles in Earth: Indigenous Versus Exogenous Sources Based on Highly Siderophile, Volatile Siderophile, and Light Volatile Elements

NASA Technical Reports Server (NTRS)

Righter, K.; Danielson, L.; Pando, K. M.; Marin, N.; Nickodem, K.

2015-01-01

Origin of Earth's volatiles has traditionally been ascribed to late accretion of material after major differentiation events - chondrites, comets, ice or other exogenous sources. A competing theory is that the Earth accreted its volatiles as it was built, thus water and other building blocks were present early and during differentiation and core formation (indigenous). Here we discuss geochemical evidence from three groups of elements that suggests Earth's volatiles were acquired during accretion and did not require additional sources after differentiation.

Studying the impact of different climate engineering techniques on ocean acidification with the Max Planck Institute Earth System Model

NASA Astrophysics Data System (ADS)

Gonzalez, M. F.; Ilyina, T.; Sonntag, S.

2016-02-01

In order to counterbalance the consequences of climate change, different climate engineering (CE) technologies have been suggested. Nonetheless, knowledge about their mitigation potential and side-effects remains sparse. Ocean alkalinization (OA) is an ocean-based carbon dioxide removal method, that aims at enhancing the natural process of weathering by which atmospheric CO2 is absorbed and stored in the ocean via chemical sequestration. Large-scale afforestation can also boost the uptake of CO2 by terrestrial biological systems and it is commonly considered as CE method. Stratospheric sulfur injection is a solar radiation management technique that has been proposed in order to enhance the Earth's albedo, mimicking the release of sulfur particles into the atmosphere during volcanic eruptions and the subsequent decrease in surface atmospheric temperatures. We explore the mitigation potential and side-effects of these CE technologies using the Max Planck Institute Earth System Model. Our scenarios are designed in order to test under what conditions it is possible to achieve a climate state that resembles the one of the representative concentration pathway (RCP) 4.5 under RCP8.5 greenhouse gas emissions. Direct and indirect effects of the OA method on the oceanic carbon cycle, differ strongly from those associated with afforestation and stratospheric sulfur injection. This is because they depend upon joint responses and synergies between different elements of the Earth system; thus, effects on the oceanic carbon cycle are not intuitively understood. Changes in the strength of the marine carbon sink, seawater pH and saturation state of carbonate minerals will be discussed. Additionally, collateral changes in marine biota and ocean biogeochemistry will be presented.

Synergetic Effect of Dy2O3 and Ca Co-Dopants towards Enhanced Coercivity of Rare Earth Abundant RE-Fe-B Magnets.

PubMed

Li, Yingfei; Tian, Na; Fan, Xiaodong; You, Caiyin; Pei, Wenli; Cheng, Zhenxiang

2017-12-13

Low coercivity is the main disadvantage of RE-Fe-B permanent magnets containing highly abundant rare earths (RE: La, Ce) from the application point of view, even though they exhibit many cost and resource advantages. In this work, an industrial mixed rare earth alloy (RE 100  = La 30.6 Ce 50.2 Pr 6.4 Nd 12.8 ) with a high amount of the more abundant elements was adopted to fabricate RE-Fe-B permanent magnets by means of mechanical alloying accompanied by post-annealing. A synergetic effect towards enhancing the coercivity was observed after co-doping with Dy 2 O 3 and Ca, with the coercivity increasing from 2.44 kOe to 11.43 kOe for co-dopant percentages of 7 wt.% Dy 2 O 3  + 2.3 wt.% Ca. Through analysis of the phase constituents and microstructure, it was determined that part of the Dy atoms entered the matrix of RE 2 Fe 14 B phase to enhance the magnetocrystalline anisotropy; due to the reductive effect of Ca on Dy 2 O 3 , nanocrystals of Dy-rich RE 2 Fe 14 B were present throughout the matrix, which could increase the resistance to domain wall movement. These are the dominant factors behind the improvement of the coercivity of the RE-Fe-B magnets with highly abundant RE elements.

A volatile rich Earth's core?

NASA Astrophysics Data System (ADS)

Morard, G.; Antonangeli, D.; Andrault, D.; Nakajima, Y.

2017-12-01

The composition of the Earth's core is still an open question. Although mostly composed of iron, it contains impurities that lower its density and melting point with respect to pure Fe. Knowledge of the nature and abundance of light elements (O, S, Si, C or H) in the core has major implications for establishing the bulk composition of the Earth and for building the model of Earth's differentiation. Geochemical models of the Earth's formation point out that its building blocks were depleted in volatile elements compared to the chondritic abundance, therefore light elements such as S, H or C cannot be the major elements alloyed with iron in the Earth's core. However, such models should be compatible with the comparison of seismic properties of the Earth's core and physical properties of iron alloys under extreme conditions, such as sound velocity or density of solid and liquid. The present work will discuss the recent progress for compositional model issued from studies of phase diagrams and elastic properties of iron alloys under core conditions and highlight the compatibility of volatile elements with observed properties of the Earth's core, in potential contradiction with models derived from metal-silicate partitioning experiments.

Earth Observatory Satellite system definition study. Report no. 5: System design and specifications. Part 1: Observatory system element specifications

NASA Technical Reports Server (NTRS)

1974-01-01

The performance, design, and quality assurance requirements for the Earth Observatory Satellite (EOS) Observatory and Ground System program elements required to perform the Land Resources Management (LRM) A-type mission are presented. The requirements for the Observatory element with the exception of the instruments specifications are contained in the first part.

Targeting heavy rare earth elements in carbonatite complexes