Yttrium and lanthanum recovery from low cerium carbonate, yttrium carbonate and yttrium concentrate

International Nuclear Information System (INIS)

Vasconcelos, Mari Estela de

2006-01-01

In this work, separation, enrichment and purification of lanthanum and yttrium were performed using as raw material a commercial low cerium rare earth concentrate named LCC (low cerium carbonate), an yttrium concentrate named 'yttrium carbonate', and a third concentrated known as 'yttrium earths oxide. The first two were industrially produced by the late NUCLEMON - NUCLEBRAS de Monazita e Associados Ltda, using Brazilian monazite. The 'yttrium earths oxide' come from a process for preparation of lanthanum during the course of the experimental work for the present thesis. The following techniques were used: fractional precipitation with urea; fractional leaching of the LCC using ammonium carbonate; precipitation of rare earth peroxycarbonates starting from the rare earth complex carbonates. Once prepared the enriched rare earth fractions the same were refined using the ion exchange chromatography with strong cationic resin without the use of retention ion and elution using the ammonium salt of ethylenediaminetetraacetic acid. With the association of the above mentioned techniques were obtained pure oxides of yttrium (>97,7%), lanthanum (99,9%), gadolinium (96,6%) and samarium (99,9%). The process here developed has technical and economic viability for the installation of a large scale unity. (author)

On the formation and structural properties of hexagonal rare earth (Y, Gd, Dy, Er and Yb) disilicide thin films

Energy Technology Data Exchange (ETDEWEB)

Geenen, F.A., E-mail: Filip.Geenen@UGent.be [Department of Solid-State Sciences, Ghent University, 9000 Gent (Belgium); Knaepen, W. [Department of Solid-State Sciences, Ghent University, 9000 Gent (Belgium); Demeulemeester, J. [Instituut voor Kern- en Stralingsfysica, KU Leuven, B-3001 Leuven (Belgium); De Keyser, K. [Department of Solid-State Sciences, Ghent University, 9000 Gent (Belgium); Jordan-Sweet, J.L.; Lavoie, C. [IBM T.J. Watson Research Center, Yorktown Heights, NY (United States); Vantomme, A. [Instituut voor Kern- en Stralingsfysica, KU Leuven, B-3001 Leuven (Belgium); Detavernier, C. [Department of Solid-State Sciences, Ghent University, 9000 Gent (Belgium)

2014-10-25

Highlights: • Solid-state reaction is studied of a several rare earth thin films with Si substrates. • h-GdSi{sub 1.7} grains have an epitaxial texture on both Si 1 0 0 and Si 1 1 1. • Formation temperature of h-RESi{sub 1.7} correlates with lattice parameter of the h-phase. - Abstract: A systematic study was performed of the solid state reaction between a 100 nm thick layer of a rare earth metal and a Si substrate. The solid state reaction of five different rare earth metals (yttrium, gadolinium, dysprosium, erbium and ytterbium) were studied by in situ X-ray diffraction measurements on Si(1 0 0), Si(1 1 1) and poly-Si. This allowed us to make a comparison between the different systems. The formation temperature of h-RESi{sub 1.7} are the highest on Si(1 1 1) and the lowest on poly-Si for all examined RE metals. Additionally, the texture of the Gd disilicide phase on Si(1 0 0) and Si(1 1 1) was investigated by means of ex situ pole figure measurements. The epitaxial relationship of hexagonal GdSi{sub 1.7} and orthorhombic GdSi{sub 2} on the different Si substrates is determined. The epitaxial growth is the strongest on Si(1 1 1)

First-principles study of rare-earth (RE) cobaltites (RE=Nd,Sm,Gd,Dy,Er,Lu)

Science.gov (United States)

Topsakal, M.; Wentzcovitch, R. M.

2014-12-01

The lanthanide series of the periodic table comprises 15 members ranging from Lanthanum (La) to Lutetium (Lu). Although they are more abundant than silver, and some of them are more abundant than lead, they are known as rare-earth (RE) elements. The "rare" in their name refers to the difficulty of obtaining the pure elements, not to their abundances in nature. They are never found as free metals in the Earth's crust and do not exist as pure minerals. Using first-principles plane-wave calculations, we investigate the structural and electronic properties of rare-earth cobaltites (RECoO3). Structurally consistent Hubbard U treatment was shown to essential for proper description of strongly correlated cobalt-d electrons. We successfully capture the experimentally observed structural trends and give first-principles insights on interesting phenomena related with the cobalt spin state change. It was demonstrated that increase of crystal-field splitting energy between eg-t2g orbitals and shrinking of unoccupied σ*-bonding eg bands are responsible for the increase of onset spin-state transition temperature along the series.

Growth and properties of Nd:(Lu xGd 1-x) 3Ga 5O 12 laser crystal by Czochralski method

Science.gov (United States)

Jia, Zhitai; Tao, Xutang; Yu, Haohai; Dong, Chunming; Zhang, Jian; Zhang, Huaijin; Wang, Zhengping; Jiang, Minhua

2008-10-01

In this paper we report the growth and characterization of Nd:(Lu xGd 1-x) 3Ga 5O 12 crystal for the first time. The polycrystalline materials were synthesized by conventional solid-state reaction. Single crystal with good optical quality was successfully obtained and the dimensions of the as-grown crystal were Ø21 × 30 mm 3. X-ray powder diffraction studies confirm that the Nd:(Lu xGd 1-x) 3Ga 5O 12 crystal is isostructural with Gd 3Ga 5O 12 with unit cell parameter of 1.2361 nm which is less than that of Gd 3Ga 5O 12 crystal (1.2376 nm). The absorption and emission spectra of the crystal at room temperature have also been studied. Continuous-wave (CW) laser performance at 1.06 μm has been demonstrated on the crystal.

Cross Section Measurements for Some Elements Suited as Thermal Spectrum indicators: Cd, Sm, Gd and Lu

Energy Technology Data Exchange (ETDEWEB)

Sokolowski, E.; Pekarek, H.; Jonsson, E.

1964-05-15

The effective cross sections of Cd, Sm, Gd and Lu have been measured by the oscillator technique in the spectrum of the central channel of the Swedish reactor R1. For Cd, Sm and Gd the 2200 m/s cross sections were deduced on the basis of Westcott's g and s factors. The values obtained were generally in agreement with other recent values obtained by integral methods, although a systematic trend indicated that the value T{sub n} - T{sub m} = 29 {+-} 10 deg C for the neutron spectrum, measured with a fast chopper, was slightly too high. A new value of T{sub n} - T{sub m} = 22.5 {+-} 3.5 deg C was deduced and new 2200 m/s cross sections were obtained by iteration. For natural Lu, the energy dependence of the cross section is not well known. Certain assumptions about the cross section function led to unreasonably high values for the 2200 m/s cross section. Complementary differential measurements of the cross sections of Cd, Sm and Gd were made with the Rl fast chopper. For Cd and Sm the 2200 m/s cross section thus obtained agreed within experimental error with those obtained from the integral measurements. For Gd, the chopper measured value was higher, confirming earlier findings and indicating that the Westcott g factor for Gd is too high. Cd: Integral meas. : {sigma}(2200) = 2,390 {+-} 45 b; Differential meas. : {sigma}(2200) = 2,445 {+-} 25 b; Sm: Integral meas. : {sigma}(2200) = 5,880 {+-} 90 b; Differential meas. : {sigma}(2200) = 5,740 {+-} 150 b; Gd: Integral meas. : {sigma}(2200) = 46,470 {+-} 550 b; Differential meas. : {sigma}(2200) = 47,900 {+-} 700 b.

Cross Section Measurements for Some Elements Suited as Thermal Spectrum indicators: Cd, Sm, Gd and Lu

Energy Technology Data Exchange (ETDEWEB)

Sokolowski, E; Pekarek, H; Jonsson, E

1964-05-15

The effective cross sections of Cd, Sm, Gd and Lu have been measured by the oscillator technique in the spectrum of the central channel of the Swedish reactor R1. For Cd, Sm and Gd the 2200 m/s cross sections were deduced on the basis of Westcott's g and s factors. The values obtained were generally in agreement with other recent values obtained by integral methods, although a systematic trend indicated that the value T{sub n} - T{sub m} = 29 {+-} 10 deg C for the neutron spectrum, measured with a fast chopper, was slightly too high. A new value of T{sub n} - T{sub m} = 22.5 {+-} 3.5 deg C was deduced and new 2200 m/s cross sections were obtained by iteration. For natural Lu, the energy dependence of the cross section is not well known. Certain assumptions about the cross section function led to unreasonably high values for the 2200 m/s cross section. Complementary differential measurements of the cross sections of Cd, Sm and Gd were made with the Rl fast chopper. For Cd and Sm the 2200 m/s cross section thus obtained agreed within experimental error with those obtained from the integral measurements. For Gd, the chopper measured value was higher, confirming earlier findings and indicating that the Westcott g factor for Gd is too high. Cd: Integral meas. : {sigma}(2200) = 2,390 {+-} 45 b; Differential meas. : {sigma}(2200) = 2,445 {+-} 25 b; Sm: Integral meas. : {sigma}(2200) = 5,880 {+-} 90 b; Differential meas. : {sigma}(2200) = 5,740 {+-} 150 b; Gd: Integral meas. : {sigma}(2200) = 46,470 {+-} 550 b; Differential meas. : {sigma}(2200) = 47,900 {+-} 700 b.

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

Science.gov (United States)

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

Radioluminescence studies of colloidal oleate-capped β-Na(Gd,Lu)F4:Ln3+ nanoparticles (Ln = Ce, Eu, Tb).

Science.gov (United States)

Cooper, Daniel R; Capobianco, John A; Seuntjens, Jan

2018-04-26

We report on the synthesis, characterization, and radioluminescence quantification of several new varieties of nanoparticles with the general composition β-NaLnF4, incorporating known luminescent activator/sensitizer pairs. Using Monte Carlo modeling to complement luminescence measurements, we have calculated the radioluminescence yields and intrinsic conversion efficiencies of colloidally-dispersed nanoparticles by comparison to an organic liquid scintillator. While five of the compositions had low to modest radioluminescence yields relative to bulk materials, colloidal β-Na(Lu0.65Gd0.2Tb0.15)F4 displayed a strong output of 39 460 photons per MeV absorbed, comparable to some of the best non-hygroscopic bulk crystal scintillators and X-ray phosphors such as Gd2O2S:Tb. Measurements of β-Na(Lu0.65Gd0.2Tb0.15)F4 powder samples revealed persistent luminescence as well as stable charge trapping, warranting further investigation.

Indides RE{sub 3}T{sub 2}In{sub 4} (RE = Y, Gd-Tm, Lu; T = Ni, Ru, Rh) with a ZrNiAl superstructure

Energy Technology Data Exchange (ETDEWEB)

Heying, Birgit; Niehaus, Oliver; Rodewald, Ute C.; Poettgen, Rainer [Univ. Muenster (Germany). Inst. fuer Anorganische und Analytische Chemie

2016-07-01

Three series of rare earth-transition metal-indides RE{sub 3}T{sub 2}In{sub 4} (RE=Y, Gd-Tm, Lu; T=Ni, Ru, Rh) were synthesized from arc-melted RE{sub 3}T{sub 2} precursor compounds and indium tear shot in sealed niobium ampoules using different annealing sequences. The new indides crystallize with the hexagonal Lu{sub 3}Co{sub 2}In{sub 4}-type structure, space group P anti 6. All samples were characterized on the basis of Guinier powder patterns and six structures were refined from single crystal X-ray diffractometer data. The RE{sub 3}T{sub 2}In{sub 4} structures are derived from the ZrNiAl type through RE/In ordering, paralleled by a symmetry reduction from P anti 62m to P anti 6. This induces twinning for some of the investigated crystals. The main crystal chemical motifs of the RE{sub 3}T{sub 2}In{sub 4} structures are trigonal prisms of rare earth, respectively indium atoms that are filled by the transition metals.

Luminescence of Eu:Y3Al5O12, Eu:Lu3Al5O12, and Eu:GdAlO3 Nanocrystals Synthesized by Solution Combustion

Science.gov (United States)

Vilejshikova, E. V.; Khort, A. A.; Podbolotov, K. B.; Loiko, P. A.; Shimanski, V. I.; Shashkov, S. N.; Yumashev, K. V.

2017-11-01

Nanocrystals of rare-earth garnets Y3Al5O12 and Lu3Al5O12 and perovskite GdAlO3 highly doped (10-20 at%) with Eu3+ are synthesized by the solution combustion technique and subsequent annealing in air at 800 and 1300oC. Their structure, morphology, and phase composition are studied. These materials exhibit intense red luminescence under UV excitation. Eu:GdAlO3 luminescence has CIE 1931 color coordinates (0.632, 0.368); dominant wavelength, 599.6 nm; and color purity, >99%. Judd-Ofelt parameters, luminescence branching ratios, and lifetimes of the Eu3+ 5D0 state are determined. The luminescence quantum yield for Eu:GdAlO3 (10 at%) reaches 74% with a lifetime of 1.4 ms for the 5D0 state. The synthesized materials are promising for red ceramic phosphors.

Lanthanide 4f-level location in AVO4:Ln3+ (A = La, Gd, Lu) crystals

NARCIS (Netherlands)

Krumpel, A.H.; Van der Kolk, E.; Cavalli, E.; Boutinaud, P.; Bettinelli, M.; Dorenbos, P.

2009-01-01

The spectral properties of LaVO4, GdVO4 and LuVO4 crystals doped with Ce3+, Pr3+, Eu3+ or Tb3+ have been investigated in order to determine the position of the energy levels relative to the valence and conduction bands of the hosts along the trivalent and divalent lanthanide series. Pr3+ and Tb3+

Multi-component Ce doped (Gd,Y,La,Lu)3(AlGaSc)5O12 garnets – A new story in the development of scintillating single crystalline film screens

International Nuclear Information System (INIS)

Zorenko, Yu.; Gorbenko, V.; Savchyn, V.; Zorenko, T.; Fedorov, A.; Wrzesinski, H.; Vasylkiv, Ya.

2013-01-01

The paper is dedicated to development of the scintillators based on single crystalline films of Ce doped (GdLaYLu) 3 (AlGaSc) 5 O 12 multi-component garnets onto Gd 3 Ga 5 O 12 substrates using the liquid phase epitaxy method. -- Highlights: •Growth of Ce doped (GdYLaLu) 3 (AlGaSc) 5 O 12 garnets films by LPE method. •Luminescent and scintillation properties of Ce doped (GdYLaLu) 3 (AlGaSc) 5 O 12 films. •Influence of Pb 2+ flux related impurity on the light yield of Ce 3+ emission

Charge Carrier Trapping Processes in RE2O2S (RE = La, Gd, Y, and Lu)

NARCIS (Netherlands)

Luo, H.; Bos, A.J.J.; Dorenbos, P.

2017-01-01

Two different charge carrier trapping processes have been investigated in RE2O2S:Ln3+ (RE = La, Gd, Y, and Lu; Ln = Ce, Pr, and Tb) and RE2O2S:M (M = Ti4+ and Eu3+). Cerium, praseodymium and terbium act as recombination centers and hole trapping centers while host intrinsic defects provide the

Rare earth activated yttrium aluminate phosphors with modulated luminescence.

Science.gov (United States)

Muresan, L E; Popovici, E J; Perhaita, I; Indrea, E; Oro, J; Casan Pastor, N

2016-06-01

Yttrium aluminate (Y3 A5 O12 ) was doped with different rare earth ions (i.e. Gd(3+) , Ce(3+) , Eu(3+) and/or Tb(3+) ) in order to obtain phosphors (YAG:RE) with general formula,Y3-x-a Gdx REa Al5 O12 (x = 0; 1.485; 2.97 and a = 0.03). The synthesis of the phosphor samples was done using the simultaneous addition of reagents technique. This study reveals new aspects regarding the influence of different activator ions on the morpho-structural and luminescent characteristics of garnet type phosphor. All YAG:RE phosphors are well crystallized powders containing a cubic-Y3 Al5 O12 phase as major component along with monoclinic-Y4 Al2 O9 and orthorhombic-YAlO3 phases as the impurity. The crystallites dimensions of YAG:RE phosphors vary between 38 nm and 88 nm, while the unit cell slowly increase as the ionic radius of the activator increases. Under UV excitation, YAG:Ce exhibits yellow emission due to electron transition in Ce(3+) from the 5d level to the ground state levels ((2) F5/2 , (2) F7/2 ). The emission intensity of Ce(3+) is enhanced in the presence of the Tb(3+) ions and is decreased in the presence of Eu(3+) ions due to some radiative or non-radiative processes that take place between activator ions. By varying the rare earth ions, the emission colour can be modulated from green to white and red. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Y/Gd-free yellow Lu{sub 3}Al{sub 5}O{sub 12}:Ce{sup 3+} phosphor for white LEDs

Energy Technology Data Exchange (ETDEWEB)

Park, Kwangwon [Department of Display Science and Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of); Kim, Taehoon; Yu, Youngmoon [LED-Marine Convergence Technology R& BD Center, Pukyong National University, Busan 608−739 (Korea, Republic of); Seo, Kwangil [L-Stone Co. Ltd., Bucheon 421−807 (Korea, Republic of); Kim, Jongsu, E-mail: jsukim@pknu.ac.kr [Department of Display Science and Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

2016-05-15

Solid solubility limit of Ce{sup 3+} ions into Lu-based garnet, Lu{sub 3(1−x)}Ce{sub 3x}Al{sub 5}O{sub 12}, was determined as below 6.7 mol% (3x<0.2 mol) through Raman spectra and X−ray diffraction patterns. Above the solid solubility limit (3x≥0.2 mol), Lu{sub 3(1−x)}Ce{sub 3x}Al{sub 5}O{sub 12} phosphors showed the significant redshift to the yellow spectral region without Y{sup 3+} and Gd{sup 3+} ions. The redshift was explained in terms of the local compressive strain at the Ce{sup 3+} sites. The optimized sample (3x=0.4 mol) had a dominant emission wavelength of 548 nm, color coordinate of CIEx=0.421, CIEy=0.548, quantum efficiency of 80%, absorbance of 91%, lumen maintenance of 90% and high color stability at 473 K under 450 nm excitation wavelength, suggesting substitutability for the commercial yellow (Y, Gd){sub 3}(Al, Ga){sub 5}O{sub 12}:Ce{sup 3+} phosphor. The measured decay times at higher Ce{sup 3+} concentration are significantly shortened at higher temperature than that of those at lower Ce{sup 3+} concentration. The yellow Lu{sub 2.6}Ce{sub 0.4}Al{sub 5}O{sub 12} and a commercial red (Sr, Ca)AlSiN{sub 3}:Eu{sup 2+} phosphor were applied to the pc-WLED, it gave an excellent luminous efficiency (138 lm/W) with a slightly lower color rendering index (Ra=76.4) under correlated color temperature of 6500 K compared to those of the (Y, Gd){sub 3}(Al, Ga){sub 5}O{sub 12}:Ce{sup 3+}-based one (136 lm/W, Ra=78.7). Especially, the quantities of the used phosphors were significantly decreased by 20% for the yellow LuAG:Ce and by 40% for the red (Sr, Ca)AlSiN{sub 3}:Eu{sup 2+}. Thus, the Y/Gd−free pure LuAG:Ce yellow phosphors can be used as alternative to the commercial yellow YAG:Ce phosphor.

The isolation and the separation of Sm, Gd, Dy by extraction

International Nuclear Information System (INIS)

Biyantoro, D.; Lahagu, F.; Basuki, K.T.; Handini, T.; Rosyidin

1996-01-01

The isolation of yttrium and separation of Sm, Gd, y with extraction has been investigated. The steps of the process include of this research were the production the concentrate of lanthanide, the dilution, the isolation of yttrium, and the separation of the Sm, Gd, Dy. The first step was the digestion of xenotime sand, the extraction, the dilution, the filtration, the precipitation, the baking production a lanthanide oxide. The step was the separation of yttrium, the stripping, and the calcination production of yttrium oxide. And the third process was the separation of Sm, Gd, Dy by extraction process using method liquid-liquid extraction with extractant of D 2 EHPA and a solvent of dodecane. From the result have been found concentration of yttrium oxide = 88,71 %. The optimum condition of the separation of Gd/Dy have been found : the concentration of HNO 3 = 0,5 M, time of extraction = 15 minutes, and the concentration of extractant = 30 % D 2 EHPA in dodecane. The results of this condition were the distribution coefficient of Gd = 2,226, the distribution coefficient of Dy = 3,762, and the separation factor of Gd/Dy = 0,592. (author)

Light emission efficiency and imaging performance of Lu{sub 2}O{sub 3}:Eu nanophosphor under X-ray radiography conditions: Comparison with Gd{sub 2}O{sub 2}S:Eu

Energy Technology Data Exchange (ETDEWEB)

Seferis, I. [Faculty of Chemistry, Wroclaw University, 14F Joliot-Curie Street, 50-383 Wroclaw (Poland); Department of Medical Physics, Medical School, University of Patras, 265 00 Patras (Greece); Michail, C.; Valais, I. [Department of Biomedical Engineering, Technological Educational Institute of Athens, 122 10 Athens (Greece); Zeler, J. [Faculty of Chemistry, Wroclaw University, 14F Joliot-Curie Street, 50-383 Wroclaw (Poland); Liaparinos, P.; Fountos, G.; Kalyvas, N.; David, S. [Department of Biomedical Engineering, Technological Educational Institute of Athens, 122 10 Athens (Greece); Stromatia, F. [Department of Radiology and Nuclear Medicine, “IASO” General Hospital, Mesogion 264, 15562 Holargos (Greece); Zych, E. [Faculty of Chemistry, Wroclaw University, 14F Joliot-Curie Street, 50-383 Wroclaw (Poland); Kandarakis, I., E-mail: kandarakis@teiath.gr [Department of Biomedical Engineering, Technological Educational Institute of Athens, 122 10 Athens (Greece); Panayiotakis, G. [Department of Medical Physics, Medical School, University of Patras, 265 00 Patras (Greece)

2014-07-01

Nanocrystallic europium-activated lutetium oxide (Lu{sub 2}O{sub 3}:Eu) is a strong candidate for use in digital medical imaging applications, due to its spectroscopic and structural properties. The aim of the present study was to investigate the imaging and efficiency properties of a 33.3 mg/cm{sup 2} Lu{sub 2}O{sub 3}:Eu scintillating screen coupled to a high resolution RadEye HR CMOS photodetector under radiographic imaging conditions. Since Lu{sub 2}O{sub 3}:Eu emits light in the red wavelength range, the light emission efficiency and the imaging performance were compared with results for a Gd{sub 2}O{sub 2}S:Eu phosphor screen. Parameters such as the Absolute Efficiency (AE), the X-ray Luminescence Efficiency (XLE), and the Detector Quantum Gain (DQG), were investigated. The imaging characteristics of Lu{sub 2}O{sub 3}:Eu nanophosphor screen were investigated in terms of the Modulation Transfer Function (MTF), the Normalized Noise Power Spectrum (NNPS) and the Detective Quantum Efficiency (DQE). It was found that Lu{sub 2}O{sub 3}:Eu nanophosphor has higher AE and XLE by a factor of 1.32 and 1.37 on average, respectively, in the whole radiographic energy range in comparison with the Gd{sub 2}O{sub 2}S:Eu screen. DQG was also found higher in the energy range from 50 kVp to 100 kVp and comparable thereafter. The imaging quality of Lu{sub 2}O{sub 3}:Eu nanophosphor coupled to the CMOS sensor was found to outmatch in any aspect in comparison with the Gd{sub 2}O{sub 2}S:Eu screen. These results indicate that Lu{sub 2}O{sub 3}:Eu nanophosphor could be considered for further research in order to be used in medical imaging applications. - Highlights: • AE and XLE of Lu{sub 2}O{sub 3}:Eu nanophosphor were higher by a factor of 1.32 and 1.37 than Gd{sub 2}O{sub 2}S:Eu. • DQG was higher from 50 to 100 kVp and comparable thereafter. • Imaging performance of Lu{sub 2}O{sub 3}:Eu/CMOS was better than that of Gd{sub 2}O{sub 2}S:Eu/CMOS.

Ternary silicides ScIr{sub 4}Si{sub 2} and RERh{sub 4}Si{sub 2} (RE = Sc, Y, Tb-Lu) and quaternary derivatives RERh{sub 4}Si{sub 2-x}Sn{sub x} (RE = Y, Nd, Sm, Gd-Lu) - structure, chemical bonding, and solid state NMR spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Vosswinkel, Daniel; Benndorf, Christopher; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Eckert, Hellmut [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Sao Paulo Univ., Sao Carlos (Brazil). Inst. of Physics; Matar, Samir F. [Bordeaux Univ., CNRS, ICMCB, UPR 9048, Pessac (France)

2016-11-01

The silicides ScIr{sub 4}Si{sub 2} and RERh{sub 4}Si{sub 2} (RE = Sc, Y, Tb-Lu) and silicide stannides RERh{sub 4}Si{sub 2-x}Sn{sub x}(RE = Y, Nd, Sm, Gd-Lu) were synthesized from the elements by arc-melting and subsequent annealing. The new compounds crystallize with the orthorhombic YRh{sub 4}Ge{sub 2} type structure, space group Pnma. They were characterized by X-ray powder patterns and several structures were refined from single crystal X-ray diffractometer data. The main structural motifs of this series of silicides are tricapped trigonal prisms formed by the transition metal and rare earth atoms. One of the two crystallographically independent silicon sites allows for formation of solid solutions with tin, exemplarily studied for ErRh{sub 4}Si{sub 2-x}Sn{sub x}. Electronic structure calculations reveal strong covalent Rh-Si bonding as the main stability factor. Multinuclear ({sup 29}Si, {sup 45}Sc, and {sup 89}Y) magic-angle spinning (MAS) NMR spectra of the structure representatives with diamagnetic rare-earth elements (Sc, Y, Lu) are found to be consistent with the crystallographic data and specifically confirm the selective substitution of Sn in the Si2 sites in the quaternary compounds YRh{sub 4}SiSn and LuRh{sub 4}SiSn.

Study of 57Fe Mössbauer effect in RFe2Zn20 (R = Lu, Yb, Gd)

Science.gov (United States)

Bud'ko, Sergey L.; Kong, Tai; Ma, Xiaoming; Canfield, Paul C.

2015-08-01

We report measurements of 57Fe Mössbauer spectra for RFe2Zn20 (R = Lu, Yb, Gd) from  ˜4.5 K to room temperature. The obtained isomer shift values are very similar for all three compounds, their temperature dependence was analyzed within the Debye model and resulted in an estimate of the Debye temperatures of 450-500 K. The values of quadrupole splitting at room temperature change with the cubic lattice constant a in a linear fashion. For GdFe2Zn20, ferromagnetic order is seen as an appearance of a sextet in the spectra. The 57Fe site hyperfine field for T\\to 0 was evaluated to be  ˜2.4 T.

In-band pumping of expitaxially grown Er:(Gd,Lu)2O3 waveguides for active integrated optical devices

NARCIS (Netherlands)

Kahn, A.; Kühn, H.; Heinrich, S.; Gün, T.; Tellkamp, F.; Petermann, K.; Bradley, J.; Ay, F.; Worhoff, Kerstin; Pollnau, Markus; Kuzminykh, Y.; Luo, Y.; Hoffmann, P.; Huber, G.

Monocrystalline lattice matched Er(0.6%):(Gd, Lu)2O3 films with thicknesses up to 3 �?�m and nearly atomically flat surfaces have been deposited on Y2O3 substrates by Pulsed Laser Deposition (PLD). The epitaxial growth has been verified in-situ by Reflection High Energy Electron Diffraction (RHEED).

Natural radioactive nuclides 138La and 176Lu in rare earth ore samples

International Nuclear Information System (INIS)

Zhang Weiping; Shen Jianfeng; Lu Zhaolun; Jiang Rangrong

1993-01-01

The contents of 1 '3 8 La and 176 Lu in some rare earth mines have been measured with a HPGE γ spectrometer. The measurements show that the contents of 138 La and 176 Lu in one rare earth mine are remarkably different from those in the other and they do not display a proportional relation, and that the contents of 40 K in this mine are very low

ALnS2:RE (A=K, Rb; Ln=La, Gd, Lu, Y): New optical materials family

International Nuclear Information System (INIS)

Jarý, V.; Havlák, L.; Bárta, J.; Mihóková, E.; Buryi, M.; Nikl, M.

2016-01-01

In the presented review paper, new potentially interesting material family, RE-doped ternary sulfides ALnS 2 (RE=Ce, Pr, Sm, Eu, Tb, Tm; A=Rb, K; Ln=La, Gd, Lu, Y) is discussed. Their synthesis is described and the structural and optical properties, characterized by methods of X-ray diffraction, time-resolved luminescence spectroscopy and electron paramagnetic resonance, are summarized and reviewed especially with respect to the influence of their composition. All samples discussed were synthesized in the form of transparent crystalline hexagonal platelets by chemical reaction under the flow of hydrogen sulfide. Their luminescence characteristics, including absorption, radioluminescence, photoluminescence excitation and emission spectra and decay kinetics, were measured and evaluated in a broad temperature (8–800 K) and concentration (0.002–20% of dopants) range. The application potential of mentioned compounds in the field of white LED solid state lightings or X-ray phosphors is thoroughly discussed. - Highlights: • RE-doped ALnS 2 (A=K, Rb; Ln=La, Gd, Lu, Y) were synthesized. • Their optical characteristics are summarized. • Concentration and temperature dependences of luminescence features investigated. • EPR technique is employed to explain Eu 2+ incorporation into KLuS 2 host. • The application potential in white LED and X-ray phosphors is discussed.

An XRF method for determination of common rare earth impurities in high purity yttrium oxide

International Nuclear Information System (INIS)

Dixit, R.M.; Deshpande, S.S.

1975-01-01

An XRF method for the estimation of Eu, Gd, Tb, Dy, Ho, Er and Yb in yttrium oxide has been developed. Samples are converted to yttrium oxalate and presented to the spectrometer in the form of pressed pellets. Philips PW-1220, a semi-automatic x-ray spectrometer, is used for the analysis. Line interference problems are studied for selecting analysis lines. For the elements except that of Yb, the lower estimation limit is 0.005% and for Yb, it is 0.01%. The average standard deviation is approximately 5% for various elements in the concentration range of 0.005% to 1.0%. The method has been tested for its accuracy by analysing synthesized samples with known composition at three different concentrations. (author)

Cermets based on rhenium and rare earth element oxides

International Nuclear Information System (INIS)

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

1977-01-01

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

Optical and magneto-optical properties of single crystals of RFe{sub 2} (R = Gd, Tb, Ho, and Lu) and GdCo{sub 2} intermetallic compounds

Energy Technology Data Exchange (ETDEWEB)

Lee, S.J.

1999-02-12

The author has studied the diagonal and off-diagonal optical conductivity of RFe{sub 2}(R = Gd, Tb, Ho, Lu) and GdCo{sub 2} single crystals grown by the flux method. Using spectroscopic ellipsometry the author has measured the dielectric function from 1.5 to 5.5 eV. The magneto-optical Kerr spectrometer at temperatures between 7 and 295 K and applied magnetic fields between 0.5 to 1.6 T. The apparatus and calibration method are described in detail. Using magneto-optical data and optical constants he derives the experimental value of the off-diagonal conductivity components. Theoretical calculations of optical conductivities and magneto-optical parameters were performed using the tight binding-linear muffin tin orbitals method within the local spin density approximation. He applied this TB-LMTO method to LuFe{sub 2}. The theoretical results obtained agree well with the experimental data. The oxidation effects on the diagonal part of the optical conductivity were considered using a three-phase model. The oxidation effects on the magneto-optical parameters were also considered by treating the oxide layer as a nonmagnetic thin transparent layer. These corrections change not only the magnitude but also the shape of the optical conductivity and the magneto-optical parameters.

First-principles calculation of structural and energetic properties for A2Ti2O7 (A = Lu, Er, Y, Gd, Sm, Nd, La)

International Nuclear Information System (INIS)

Zhang, Z.L.; Xiao, H.Y.; Zu, Xiaotao T.; Gao, Fei; Weber, William J.

2009-01-01

A first-principles method has been employed to investigate the structural and energetic properties for A2Ti2O7 (A = Lu, Er, Y, Gd, Sm, Nd, La), including the formation energies of the cation antisite-pair, the anion Frenkel pair that defines anion-disorder, and the coupled cation antisite-pair/anion-Frenkel. It is proposed that the interaction may have more significant influence on the radiation resistance behavior of titanate pyrochlores, although the interactions are relatively much stronger than the interactions. It is found that the defect formation energies are not simple functions of the A-site cation radii. The formation energy of the cation antisite-pair increases continuously as the A-site cation varies from Lu to Gd, and then decreases continuously with the variation of the A-site cation from Gd to La, in excellent agreement with the radiation-resistance trend of the titanate pyrochlores. The band gaps in these pyrochlores were also measured, and the band gap widths changed continuously with cation radius.

A new series of rhenium VII compounds: sodium-rare earth perrhenates

International Nuclear Information System (INIS)

Slimane, Z.A.A.; Silvestre, J.-P.; Freundlich, William

1978-01-01

Synthesis by solid state reaction or in aqueous solution and radiocrystallographical study of the hexagonal sodium-rare earth perrhenates NaLn(ReO 4 ) 4 (Ln=La, Nd, Sm, Eu, Gd, Er) and of the tetragonal tetrahydrates NaLn(ReO 4 ) 4 , 4H 2 O (Ln=Eu, Gd, Er, Lu) [fr

Permeabilitas Membran Transpor Campuran Unsur Tanah Jarang (La, Nd, Gd, Lu Menggunakan Carrier (TBP : D2EHPA Melalui Supported Liquid Membrane

Directory of Open Access Journals (Sweden)

Djabal Nur Basir

2015-01-01

Full Text Available Methods that have been developed currently for the separation and purification of rare earth elements, REE’s are solvent extraction by through immobilization of an extracting agent in a porous polymeric membrane. This methods beside could increase the transport selectivity, also the amount of carrier was very few. This technique is known as supported liquid membrane, SLM. Research toward transport and separation of REE’s through SLM have been still relatively limited merely to single feed-binary mixture, and one type of carrier. The transport   membrane permeability was obtained in a mixture of REE’s (La,Nd,Gd,Lu using the carrier TBP : D2EHPA by SLM. In this SLM technique, supporting membrane PTFE (polytetrafluoroethylene was soaked in a mixture of TBP carrier (tributilfosfat as a neutral ligand and D2EHPA (acid-2- etilheksilfosfat as anionic ligand with a particular concentration ratio in the solvent kerosene as membrane phase. HCl as receiver phase and solution mixture of REE’s as feed phase. Determination of the REE’s total concentration was carried out by UV-Vis spectrophotometry with NAS (sodium alizarin sulfonate as the colouring agent at pH 4,75 and the solution absorbance was determinated at 534 nm as maximum wavelength. Transport patterns of REE’s on the variation of the concentration of total mixed carrier composition, pH, and concentration  of the receiver phase were done for 300 minutes. The optimum conditions of transport mixture of REE’s (La, Nd, Gd, Lu were feed phase pH 3,0; carrier TBP: D2EHPA (0,3:0,7 M; and receiver phase HCl 3,0 M. In this condition, the transport membrane permeability in mixture of REE’s was 0,1077 cm.menit-1 with the percent of transport was 95,24%.

Systematic hardness measurements on some rare earth garnet ...

Indian Academy of Sciences (India)

Unknown

Microhardness measurements were undertaken on twelve rare earth garnet crystals. In yttrium aluminium garnet and gadolinium ... syan (1997) has quoted a single value for Gd3Sc2Ga3O12. In the present study measurements have ... small and within the limits of experimental error. There- fore, where pure garnet crystals ...

Mutual solubility between hexane and three-n-butyl phosphate solvates of lanthanide(III) and thorium(IV) nitrates at various temperatures

International Nuclear Information System (INIS)

Keskinov, V.A.; Lishuk, V.V.; Pyartman, A.K.

2007-01-01

Phase diagrams of binary liquid systems of hexane-rare earth(III) nitrates solvates (rare earth - neodymium, gadolinium, yttrium, ytterbium, lutetium) and thorium(IV) with tri-n-butylphosphate are studied at different temperatures. Phase diagrams of binary systems consist of fields of homogeneous solutions and field of stratification into two liquid phases (I, II): phase I is enriched by hexane, and phase II - [Ln(NO 3 ) 3 (TBP) 3 ] (Ln=Nd, Gd, Y, Yb and Lu) or [Th(NO 3 ) 4 (TBP) 2 ]. Field of stratification into two liquid phases are decreased with growing temperature in binary systems [ru

A divalent rare earth oxide semiconductor: Yttrium monoxide

Energy Technology Data Exchange (ETDEWEB)

Kaminaga, Kenichi; Sei, Ryosuke [Department of Chemistry, The University of Tokyo, Tokyo 113-0033 (Japan); Department of Chemistry, Tohoku University, Sendai 980-8578 (Japan); Hayashi, Kouichi [Department of Environmental and Materials Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan); Happo, Naohisa [School of Information Sciences, Hiroshima City University, Hiroshima 731-3194 (Japan); Tajiri, Hiroo [Japan Synchrotron Radiation Research Institute (JASRI)/SPring-8, Sayo 679-5198 (Japan); Oka, Daichi; Fukumura, Tomoteru, E-mail: tomoteru.fukumura.e4@tohoku.ac.jp [Department of Chemistry, Tohoku University, Sendai 980-8578 (Japan); Hasegawa, Tetsuya [Department of Chemistry, The University of Tokyo, Tokyo 113-0033 (Japan)

2016-03-21

Rare earth oxides are usually widegap insulators like Y{sub 2}O{sub 3} with closed shell trivalent rare earth ions. In this study, solid phase rock salt structure yttrium monoxide, YO, with unusual valence of Y{sup 2+} (4d{sup 1}) was synthesized in a form of epitaxial thin film by pulsed laser deposition method. YO has been recognized as gaseous phase in previous studies. In contrast with Y{sub 2}O{sub 3}, YO was dark-brown colored and narrow gap semiconductor. The tunable electrical conductivity ranging from 10{sup −1} to 10{sup 3} Ω{sup −1 }cm{sup −1} was attributed to the presence of oxygen vacancies serving as electron donor. Weak antilocalization behavior observed in magnetoresistance indicated significant role of spin-orbit coupling as a manifestation of 4d electron carrier.

Judd–Ofelt analysis and transition probabilities of Er{sup 3+} doped KY{sub 1−x−y}Gd{sub x}Lu{sub y}(WO{sub 4}){sub 2} crystals

Energy Technology Data Exchange (ETDEWEB)

Martínez de Mendívil, Jon, E-mail: jon.martinez@uam.es [Departamento de Física de Materiales, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Lifante, Ginés [Departamento de Física de Materiales, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Pujol, Maria Cinta; Aguiló, Magdalena; Díaz, Francesc [Física i Cristalografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili, Tarragona (Spain); Cantelar, Eugenio [Departamento de Física de Materiales, Universidad Autónoma de Madrid, 28049 Madrid (Spain)

2015-09-15

In this work the transition probabilities, radiative lifetimes and branching ratios of Er{sup 3+} ions in KY{sub 1−x−y}Gd{sub x}Lu{sub y}(WO{sub 4}){sub 2} crystals have been determined. With this aim, Er{sup 3+} doped KY{sub 1−x−y}Gd{sub x}Lu{sub y}(WO{sub 4}){sub 2} crystals have been grown by means of the high temperature Top-Seeded Solution Growth. A spectroscopic analysis of Er{sup 3+} ions in this crystal has been performed following anisotropic Judd–Ofelt analysis to obtain basic spectroscopic properties. A quantum efficiency over 97% has been determined for the {sup 4}I{sub 13/2}→{sup 4}I{sub 15/2} transition, indicating that this material is adequate for the development of lasers and amplifiers working in the third telecommunication window. - Highlights: • Er{sub 0.01}:KY{sub 1−x−y}Gd{sub x}Lu{sub y}(WO{sub 4}){sub 2} crystals have been grown. • Anisotropic Judd Ofelt analysis has been carried out. • Optical transition probabilities and branching ratios have been calculated. • Radiative and non-radiative lifetimes have been obtained.

A systemic study of stepwise chlorination-chemical vapor transport characteristics of pure rare earth oxides from Sc2O3 to Lu2O3 mediated by alkaline chlorides as complex former

International Nuclear Information System (INIS)

Sun Yanhui; He Peng; Chen Huani

2007-01-01

A systematic study has been carried out for the stepwise chlorination-chemical vapor transport (SC-CVT) characteristics of pure rare earth oxides from Sc 2 O 3 to Lu 2 O 3 mediated by the vapor complexes KLnCl 4 and NaLnCl 4 (Ln = Sc, Y and La-Lu) used NaCl and KCl as complex former, respectively. The results showed that the SC-CVT characteristics are similarly for NaCl and KCl as complex former, the main deposition temperature of the rare earth chlorides LnCl 3 is in the increasing order ScCl 3 3 3 , and then with a systematically decreasing trend from the early lanthanide chlorides to the end one. The results also showed that the total transported amount of the produced chlorides is YCl 3 > ScCl 3 , and they are much higher than that of most lanthanoid chlorides. For lanthanoids, the total transported amount of chloride increases systematically from the early lanthanoid chlorides to the end one except for EuCl 3 and GdCl 3 mediated by KCl and NaCl as complex former, respectively, which showed the divergence effect of Gd in the total transport efficiency. But there are some differences in SC-CVT characteristics of pure rare earth oxide mediated by KCl and NaCl as complex former, that is the main deposition temperature region for the same rare earth element was lower for KCl than that for NaCl as complex former except for LaCl 3 , CeCl 3 , YbCl 3 and LuCl 3 , while the total transport amount of rare earth chloride for KCl as complex former is higher than that for NaCl except for LaCl 3 and EuCl 3 . More over, the discussion was carried out for Sc and Y on the one hand and the lanthanides contain 4f electron as another hand based on the 4f electron hybridization assumption. Further more, the transport characteristics of rare earth oxides with alkaline chlorides as complex former in this study were compared to that with AlCl 3 as complex former

Journal of Earth System Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

The rare earth elements like La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and the heavy metals like Mg, V, Cr, Mn, Fe, Cu, Zn, U, Th were analysed by using standard analytical methods. The Post-Archean Australian Shale composition was used to normalise the rare earth elements. It was found that the sediments ...

Critical evaluation and thermodynamic optimisation of the Si-RE systems: Part II. Si-RE system (RE = Gd, Tb, Dy, Ho, Er, Tm, Lu and Y)

International Nuclear Information System (INIS)

Kim, Junghwan; Jung, In-Ho

2015-01-01

Highlights: • The (Si-RE) (RE = Gd, Tb, Dy, Ho, Er, Tm, Lu and Y) systems have been reviewed. • The thermodynamic optimization of the (Si-RE) systems have been performed. • Systematic changes and similarities in the (Si-RE) systems were found. • The systematic approach resolved inconsistencies in the experimental data. • The systematic approach was used to assess the unexplored phase diagrams. - Abstract: A critical evaluation and optimisation of all available phase diagrams and thermodynamic data of the (Si-RE) (RE = Gd, Tb, Dy, Ho, Er, Tm, Lu and Y) systems was conducted to obtain reliable thermodynamic functions of all the phases in the system. In the thermodynamic modelling, a systematic analysis involving the similarity and periodicity observed in the lanthanide series was applied to resolve inconsistencies in the experimental data and to estimate the unknown thermodynamic properties and phase equilibria data. In particular, the phase diagrams and thermodynamic properties of (Si-Tm) and (Si-Lu) systems which are rarely investigated can be predicted from this approach. Systematic trends in thermodynamic properties of solid and liquid phases and phase diagram of the entire (Si-RE) systems were summarized

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

International Nuclear Information System (INIS)

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

1982-01-01

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

Diode-pumped continuous-wave and passively Q-switched Nd:GdLuAG laser at 1443.9 nm

Science.gov (United States)

Wu, Qianwen; Liu, Zhaojun; Zhang, Sasa; Cong, Zhenghua; Guan, Chen; Xue, Feng; Chen, Hui; Huang, Qingjie; Xu, Xiaodong; Xu, Jun; Qin, Zengguang

2017-12-01

We investigated the 1443.9 nm laser characteristics of Nd:GdLuAG crystal. Diode-end-pumping configuration was employed under both continuous-wave (CW) and passively Q-switched operations. For CW operation, the maximum average output power was 1.36 W with a slope efficiency of 15%. By using a V3+:YAG crystal as the saturable absorber, we obtained the maximum average output power of 164 mW under Q-switched operation. The corresponding pulse energy was 29.3 μJ and pulse duration was 59 ns.

A divalent rare earth oxide semiconductor: Yttrium monoxide

Science.gov (United States)

Kaminaga, Kenichi; Sei, Ryosuke; Hayashi, Kouichi; Happo, Naohisa; Tajiri, Hiroo; Oka, Daichi; Fukumura, Tomoteru; Hasegawa, Tetsuya

Rare earth sesquioxides like Y2O3 are known as widegap insulators with the highly stable closed shell trivalent rare earth ions. On the other hand, rare earth monoxides such as YO have been recognized as gaseous phase, and only EuO and YbO were thermodynamically stable solid-phase rock salt monoxides. In this study, solid-phase rock salt yttrium monoxide, YO, was synthesized in a form of epitaxial thin film by pulsed laser deposition method. YO possesses unusual valence of Y2+ ([Kr] 4d1) . In contrast with Y2O3, YO was narrow gap semiconductor with dark-brown color. The electrical conductivity was tunable from 10-1 to 103 Ω-1 cm-1 by introducing oxygen vacancies as electron donor. Weak antilocalization behavior was observed indicating significant spin-orbit coupling owing to 4 d electron carrier. The absorption spectral shape implies the Mott-Hubbard insulator character of YO. Rare earth monoixdes will be new platform of functional oxides. This work was supported by JST-CREST, the Japan Society for the Promotion of Science (JSPS) with Grant-in-Aid for Scientific Research on Innovative Areas (Nos. 26105002 and 26105006), and Nanotechnology Platform (Project No.12024046) of MEXT, Japan.

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

International Nuclear Information System (INIS)

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

2014-01-01

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

Comparative study of crystallographic, spectroscopic, and laser properties of Tm3+ in NaT(WO4)2 (T=La, Gd, Y, and Lu) disordered single crystals

Science.gov (United States)

Cano-Torres, J. M.; Rico, M.; Han, X.; Serrano, M. D.; Cascales, C.; Zaldo, C.; Petrov, V.; Griebner, U.; Mateos, X.; Koopmann, P.; Kränkel, C.

2011-11-01

Tetragonal double tungstate single crystals with formula NaT(WO4)2 have been grown by the Czochralski (T = Gd, La, Y) or by the top-seeded solution growth (T = Lu) methods with Tm concentration between 8 × 1018 and 7.85 × 1020 cm-3. The spectroscopic properties of Tm3+ in these crystals are related with the peculiarities of their I4¯ crystalline structure. Sixty-five percent of La ions in NaLa(WO4)2 are in the 2d site, while in the other crystal hosts, the lanthanide occupies preferentially the 2b site (59% in T = Gd, 74% in T = Y, and 58% in T = Lu). As a consequence, the linewidths of spectral bands associated with the electronic transitions are significantly narrower in NaLa(WO4)2 than in the rest of the isostructural crystals considered. Polarized spectroscopic measurements at 5 K and at higher temperatures, along with energy level simulation of the 4f12 configuration using a single-electron Hamiltonian, including free-ion and crystal field interactions, allowed us to determine the irreducible representation and energy of Stark levels up to the 3P0 multiplet and thus to obtain realistic partition functions (Z) used for emission cross-section calculations. In particular, for the 3F4(u) → 3H6(l) laser transition at λ ≈ 2 μm, this provides: Zl/Zu = 1.436 (T = Gd), 1.464 (T = La), 1.448 (T = Y), and 1.471 (T = Lu). Radiative lifetimes calculated by the Judd-Ofelt and Füchtbauer-Ladenburg methods are in agreement and decrease in the following order T = Gd, La, Y, and Lu, however, nonradiative losses are stronger for T = Gd and La crystals; therefore, experimental lifetimes of 1D2, 1G4, 3H4, and 3F4 Tm3+ multiplets do not change too much with crystal host. For 4.68 at.% Tm:NaY(WO4)2 crystal continuous-wave laser operation is obtained with ≈42% of slope efficiency and a record (for this crystal class) tuning capability of λ = 1847-2069 nm. The broad bandwidths, ΔλFWHM > 20 nm, of the free-running laser emission are promising for ultrafast (fs) mode

Systematic study of photoluminescence upon band gap excitation in perovskite-type titanates R 1/2Na1/2TiO3:Pr (R=La, Gd, Lu, and Y)

International Nuclear Information System (INIS)

Inaguma, Yoshiyuki; Tsuchiya, Takeshi; Katsumata, Tetsuhiro

2007-01-01

Pr 3+ -doped perovskites R 1/2 Na 1/2 TiO 3 :Pr (R=La, Gd, Lu, and Y) were synthesized, and their structures, optical absorption and luminescent properties were investigated, and the relationship between structures and optical properties are discussed. Optical band gap of R 1/2 Na 1/2 TiO 3 increases in the order R=La, Gd, Y, and Lu, which is primarily due to a decrease in band width accompanied by a decrease in Ti-O-Ti bond angle. Intense red emission assigned to f-f transition of Pr 3+ from the excited 1 D 2 level to the ground 3 H 4 state upon the band gap photo-excitation (UV) was observed for all compounds. The wavelength of emission peaks was red-shifted in the order R=La, Gd, Y, and Lu, which originates from the increase in crystal field splitting of Pr 3+ . This is attributed to the decrease in inter-atomic distances of Pr-O together with the inter-atomic distances (R, Na)-O, i.e., increase in covalency between Pr and O. The results indicate that the luminescent properties in R 1/2 Na 1/2 TiO 3 :Pr are governed by the relative energy level between the ground and excited state of 4f 2 for Pr 3+ , and the conduction and valence band, which is primarily dependent on the structure, e.g., the tilt of TiO 6 octahedra and the Pr-Ti inter-atomic distance and the site symmetry of Pr ion. - Graphical abstract: The red intense emission assigned to f-f transition of Pr 3+ from the excited 1 D 2 level to the ground 3 H 4 state upon the band gap photo-excitation (UV) was observed upon the band gap photo-excitation in perovskites R 1/2 Na 1/2 TiO 3 :Pr(R=La, Gd, Lu, and Y). It was found that the systematic changes in their luminescent properties are strongly dependent on the structure

Synthesis and characterization of Na(Gd0.5Lu0.5)F4: Nd3+,a core-shell free multifunctional contrast agent.

Science.gov (United States)

Mimun, L Christopher; Ajithkumar, G; Rightsell, Chris; Langloss, Brian W; Therien, Michael J; Sardar, Dhiraj K

2017-02-25

Compared to conventional core-shell structures, core-shell free nanoparticles with multiple functionalities offer several advantages such as minimal synthetic complexity and low production cost. In this paper, we present the synthesis and characterization of Nd 3+ doped Na(Gd 0.5 Lu 0.5 )F 4 as a core-shell free nanoparticle system with three functionalities. Nanocrystals with 20 nm diameter, high crystallinity and a narrow particle size distributions were synthesized by the solvothermal method and characterized by various analytical techniques to understand their phase and morphology. Fluorescence characteristics under near infrared (NIR) excitation at 808 nm as well as X-ray excitation were studied to explore their potential in NIR optical and X-ray imaging. At 1.0 mol% Nd concentration, we observed a quantum yield of 25% at 1064 nm emission with 13 W/cm 2 excitation power density which is sufficiently enough for imaging applications. Under 130 kVp (5 mA) power of X-ray excitation, Nd 3+ doped Na(Gd 0.5 Lu 0.5 )F 4 shows the characteristic emission bands of Gd 3+ and Nd 3+ with the strongest emission peak at 1064 nm due to Nd 3+ . Furthermore, magnetization measurements show that the nanocrystals are paramagnetic in nature with a calculated magnetic moment per particle of ~570 μB at 2T. These preliminary results support the suitability of the present nanophosphor as a multimodal contrast agent with three imaging features viz. optical, magnetic and X-ray.

Crystal fields at light rare-earth ions in Y and Lu

DEFF Research Database (Denmark)

Touborg, P.; Nevald, Rolf; Johansson, Torben

1978-01-01

Crystal-field parameters have been deduced for the light rare-earth solutes Ce, Pr, and Nd in Y or Lu hosts from measurements of the paramagnetic susceptibilities. In the analysis all multiplets in the lowest LS term were included. For a given host, crystal-field parameters divided by Stevens fac...

Yttrium and lanthanum recovery from low cerium carbonate, yttrium carbonate and yttrium concentrate; Aproveitamento de itrio e lantanio de um carbonato de terras raras de baixo teor em cerio, de um carbonato de itrio e de um oxido de terras itricas

Energy Technology Data Exchange (ETDEWEB)

Vasconcelos, Mari Estela de

2006-07-01

In this work, separation, enrichment and purification of lanthanum and yttrium were performed using as raw material a commercial low cerium rare earth concentrate named LCC (low cerium carbonate), an yttrium concentrate named 'yttrium carbonate', and a third concentrated known as 'yttrium earths oxide. The first two were industrially produced by the late NUCLEMON - NUCLEBRAS de Monazita e Associados Ltda, using Brazilian monazite. The 'yttrium earths oxide' come from a process for preparation of lanthanum during the course of the experimental work for the present thesis. The following techniques were used: fractional precipitation with urea; fractional leaching of the LCC using ammonium carbonate; precipitation of rare earth peroxycarbonates starting from the rare earth complex carbonates. Once prepared the enriched rare earth fractions the same were refined using the ion exchange chromatography with strong cationic resin without the use of retention ion and elution using the ammonium salt of ethylenediaminetetraacetic acid. With the association of the above mentioned techniques were obtained pure oxides of yttrium (>97,7%), lanthanum (99,9%), gadolinium (96,6%) and samarium (99,9%). The process here developed has technical and economic viability for the installation of a large scale unity. (author)

Lanthanoid and yttrium tellurates

Energy Technology Data Exchange (ETDEWEB)

Gonalez, C G; Guedes de Carvalho, R A [Faculdade de Engenharia, Porto (Portugal). Centro de Engenharia Quimica

1978-05-01

Preparation in aqueous medium of all the lanthanoid (except Ce and Pm) and yttrium tellurates is described. Chemical analyses, solubilities at 25/sup 0/C in water and thermograms of all the products prepared were determined. X-ray diffractograms and DTA and DTG curves of La, Gd and Yb tellurates were obtained and commented. Partial volatilization of lanthanoid is observed in the thermal analysis of tellurates.

Phase II trial of yttrium-90-DOTA-biotin pretargeted by NR-LU-10 antibody/streptavidin in patients with metastatic colon cancer

International Nuclear Information System (INIS)

Knox, S J.; Goris, M L.; Tempero, M.; Weiden, P L.; Gentner, L.; Breitz, H.; Adams, G. P.; Axworthy, D.; Gaffigan, S.; Bryan, K.; Fisher, Darrell R.; Colcher, D; Horak, I D.; Weiner, L M.

1999-01-01

A Phase II study of yttrium-90-tetra-azacyclododecanetetra-acetic acid-biotin (Y-90-DOTA-biotin) pretargeted by NR-LU-10 antibody/streptavidin (SA) was performed. The primary objectives of the study were to evaluate the efficacy and safety of this therapy in patients with metastatic colon cancer. Twenty-five patients were treated with a single dose of 110 mCi/m 2 (mean administered dose, 106.5-10.3 mCi/m 2 ) of Y-90-DOTA-biotin. There were three components of the therapy. Patients first received NR-LU-10/SA on day 1. A clearing agent (biotin-galactose-human serum albumin) was administered 48 h after the NR-LU-10/SA to remove residual circulating unbound NR-LU-10/SA. Lastly, 24 h after administration of clearing agent, patients received biotin-DOTA-labeled with 110 mCi/m 2 Y-90. All three components of the therapy were administered i.v. Both hematological and nonhematological toxicities were observed. Diarrhea was the most frequent grade 4 nonhematological toxicity (16%; with 16% grade 3 diarrhea). Hematological toxicity was less severe with 8% grade 3 and 8% grade 4 neutropenia and 8% grade 3 and 16% grade 4 thrombocytopenia. The overall response rate was 8%. Two partial responders had freedom from progression of 16 weeks. Four patients (16%) had stable disease with freedom from progression of 10-20 weeks. Despite the relatively disappointing results of this study in terms of therapeutic efficacy and toxicity, proof of principle was obtained for the pretargeting approach. In addition, valuable new information was obtained about normal tissue tolerance to low-dose-rate irradiation that will help to provide useful guidelines for future study designs

The influence of gadolinium and yttrium on biomass production and nutrient balance of maize plants

International Nuclear Information System (INIS)

Saatz, Jessica; Vetterlein, Doris; Mattusch, Jürgen; Otto, Matthias; Daus, Birgit

2015-01-01

Rare earth elements (REE) are expected to become pollutants by enriching in the environment due to their wide applications nowadays. The uptake and distribution of gadolinium and yttrium and its influence on biomass production and nutrient balance was investigated in hydroponic solution experiments with maize plants using increasing application doses of 0.1, 1 and 10 mg L −1 . It could be shown that concentrations of up to 1 mg L −1 of Gd and Y did not reduce or enhance the plant growth or alter the nutrient balance. 10 mg L −1  Gd or Y resulted in REE concentrations of up to 1.2 weight-% in the roots and severe phosphate deficiency symptoms. Transfer rates showed that there was only little transport of Gd and Y from roots to shoots. Significant correlations were found between the concentration of Gd and Y in the nutrient solution and the root tissue concentration of Ca, Mg and P. - Highlights: • Roots accumulate REE in very high concentrations. • Transfer factors from root to shoot tissue are very low, with HREE higher than MREE. • The nutrient balance of the plant is severely influenced by REE addition. • Phosphate deficiency appears at high concentrations of REE addition. - The addition of the rare-earth elements Gd and Y results in less Ca and Mg uptake and phosphate deficiency in maize plants grown in hydroponics

Selective separation of yttrium by CA-100 in the presence of a complexing agent

International Nuclear Information System (INIS)

Sun Xiaobo; Wang Yige; Li Deqian

2006-01-01

The selective separation of Y from yttrium solution containing small heavy rare earth (HRE) impurities (Ho, Er, Tm, Yb, Lu) by liquid-liquid extraction using CA-100 in the presence of a water-soluble complexing agent of ethylenediaminetetraacetic acid (EDTA) was experimentally studied at 298 K. Experiments were carried out in two feeds, Feed-I: [RE] f = 4.94 x 10 -3 M, Y = 98.5%, HRE (Ho, Er, Tm, Yb, Lu) = 1.5%; Feed-II: [RE] f = 4.94 x 10 -3 M, Y = 99.9%, HRE (Ho, Er, Tm, Yb, Lu) = 0.1%, as a function of equilibrium pH (pH eq ), the concentration ratio of [EDTA]:[HRE impurities]. It was shown that the extraction of HRE in the presence of EDTA was suppressed when compared to that of Y because of the masking effect, while the selective extraction of Y was enhanced and the separation factors increased to maximum at appropriate condition for Feed-I: Y/Ho = 1.53, Y/Er 3.09, Y/Tm = 5.61, Y/Yb = 12.04, Y/Lu = 27.51 at pH 4.37 and [EDTA]:[HRE impurities] = 4:1, for Feed-II: Y/Ho = 1.32, Y/Er = 1.91, Y/Tm = 2.00, Y/Yb 3.05, Y/Lu = 3.33 at pH 4.42 and [EDTA]:[HRE impurities] = 8:1. The separation and purification of Y by this method was discussed

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

International Nuclear Information System (INIS)

Wang, J.; Zadeii, J.M.

1986-01-01

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

Linear optical properties of Ca4EuO(BO3)3 and Eu3+ : Ca4GdO(BO3)3 crystals

International Nuclear Information System (INIS)

Antic-Fidancev, E.; Lemaitre-Blaise, M.; Porcher, P.; Caramanian, A.; Aka, G.

1998-01-01

Full text: The title compounds are now intensively studied due to their quadratic nonlinear properties in view of applications, e.g. high power laser frequency conversion. Rare earth calcium oxoborates, Ca 4 REO(BO 3 ) 3 , constitute an isostructural family along the rare earth series with RE = La - Lu, Y included. These compounds crystallize in the monoclinic biaxial crystal system with Cm (N 8) space group. They are isostructural to the calcium fluoroborate Ca 5 (BO 3 ) 3 F which is related to the fluoroapatite structure Ca 5 (PO 4 ) 3 F. The rare earth ions are located in the distorted octahedron with C s point site symmetry in the mirror plane. Two types of distorted octahedral sites exist for calcium ions. The existence of some disorder between calcium and rare earth atoms is suspected from the structural analysis. Good optical quality crystals of europium (or gadolinium) oxoborate, EuCOB (GdCOB) have been grown from the stoichiometric melt by the Czochralski pulling method. From the luminescence of the Eu 3+ doped gadolinium or in the europium stoichiometric compound very complex emission spectra have been obtained. It principally depends on the preparation method of studied samples: i) for a monocrystalline sample, a single phase with a single site is observed; ii) for a polycrystalline sample complex feature occurs. It is probably due to an expanded disorder between calcium and rare earth atoms. Practically, there is one principal site corresponding to the low symmetry site of the rare earth as expected from the structural investigation. Other minor sites are attributed to the local distortion created around the active rare earth ion. The intensity of the emission lines of Eu 3+ used as a local structural probe related to these minor sites increases when the gadolinium in Ca 4 GdO(BO 0 ) 3 is substituted by lanthanum or yttrium ions. It seems therefore evident that the synthesis of these rare earth calcium oxoborates must be realised carefully. The crystal

Structure, magnetism, and transport of single-crystalline R NiSi3 (R = Y, Gd-Tm, Lu)

Science.gov (United States)

Arantes, Fabiana R.; Aristizábal-Giraldo, Deisy; Masunaga, Sueli H.; Costa, Fanny N.; Ferreira, Fabio F.; Takabatake, Toshiro; Mendonça-Ferreira, Leticie; Ribeiro, Raquel A.; Avila, Marcos A.

2018-04-01

We report on the physical properties of the intermetallic series R NiSi3 (R =Y , Gd-Tm, Lu). High quality single crystals with platelike morphology were grown using the Sn flux method. X-ray powder diffraction data show that this series crystallizes in the orthorhombic space group Cmmm, and Laue patterns indicate that the b axis remains perpendicular to the plane of the plates. Magnetization measurements show anisotropic antiferromagnetic ground states for R = Gd-Tm with Néel temperatures ranging from TN=2.6 K (TmNiSi3) up to 32.2 K (TbNiSi3), as well as metamagnetic transitions that in some cases appear together with hysteresis (TbNiSi3,DyNiSi3, and HoNiSi3). The easy axis changes from a axis to b axis on going from R = Gd-Ho to R = Er-Tm. All transitions from antiferromagnetic to paramagnetic states are clearly marked by sharp peaks in specific heat as well as in the derivative of resistivity measurements, which show metallic temperature dependence for all compounds and residual values in the range of 1 μ Ω cm . DyNiSi3 has two close phase transitions, while HoNiSi3 presents distinct critical temperatures for applied fields in the a or c directions (10.4 and 6.3 K, respectively), pointing to possible component-specific ordering of the local magnetic moments.

Peculiarities of component interaction in {Gd, Er}-V-Sn Ternary systems at 870 K and crystal structure of RV6Sn6 stannides

International Nuclear Information System (INIS)

Romaka, L.; Stadnyk, Yu.; Romaka, V.V.; Demchenko, P.; Stadnyshyn, M.; Konyk, M.

2011-01-01

Highlights: → {Gd, Er}-V-Sn ternary systems at 870 K are characterized by formation of stannides with general compositions RV 6 Sn 6 . → Isostructural RV 6 Sn 6 compounds were also found with Y, Dy, Ho, Tm, and Lu. → The crystal structure of RV 6 Sn 6 compounds was determined by powder diffraction method. → Structural analysis showed that RV 6 Sn 6 compounds (R = Gd, Dy-Tm, Lu) are disordered; YV 6 Sn 6 is characterized by structure ordering. - Abstract: The phase equilibria in the Gd-V-Sn and Er-V-Sn ternary systems were studied at 870 K by means of X-ray and metallographic analyses in the whole concentration range. Both Gd-V-Sn and Er-V-Sn systems are characterized by formation of one ternary compound at investigated temperature, with stoichiometry RV 6 Sn 6 (SmMn 6 Sn 6 -type, space group P6/mmm, a = 0.55322(3) nm, c = 0.91949(7) nm for Gd, a = 0.55191(2) nm, c = 0.91869(8) nm for Er). Solubility of the third component in the binary compounds was not observed. Compounds with the SmMn 6 Sn 6 -type were also found with Dy, Ho, Tm, and Lu, while YV 6 Sn 6 compound crystallizes in HfFe 6 Ge 6 structure type. All investigated compounds are the first ternary stannides with rare earth elements and vanadium.

Structural relative stabilities and pressure-induced phase transitions for lanthanide trihydrides REH{sub 3} (RE=Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu)

Energy Technology Data Exchange (ETDEWEB)

Kong Bo, E-mail: kong79@yeah.net [National Key Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang 621900 (China); College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Zhang Lin, E-mail: zhanglinbox@263.net [National Key Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang 621900 (China); Chen Xiangrong [College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Zeng Tixian [College of Physics and Electronic Information, China West Normal University, Nanchong 637002 (China); Cai Lingcang [National Key Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang 621900 (China)

2012-06-15

The structures, structural relative stabilities, pressure-induced phase transitions, and equations of state for lanthanide trihydrides REH{sub 3} (RE=Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu) are systematically studied using ab initio calculations under a core state model (CSM). The obtained ground-state parameters, such as lattice constants and bulk modulus, agree well with the available data. Among the P6{sub 3}/mm, P3-bar c1, and P6{sub 3}cm structures, the P6{sub 3}cm structure is found to be the most stable structure for lanthanide trihydride via the comparison of the calculated total energies. With the help of Birch-Murnaghan equation of state, the structural transitions from hexagonal to cubic for REH{sub 3} (RE=Sm, Gd, Ho, Er, and Lu) under pressure are affirmed; especially, the similar behavior of REH{sub 3} (RE= Tb, Dy, and Tm) is reasonably predicted for the first time by this means. For the transitions, the repulsive interactions of H-H atoms may play an important role in terms of the analysis of the structures in the vicinity of the theoretical phase transition.

Structural and sensing characteristics of Gd2Ti2O7, Er2TiO5 and Lu2Ti2O7 sensing membrane electrolyte–insulator–semiconductor for bio-sensing applications

International Nuclear Information System (INIS)

Pan, Tung-Ming; Liao, Pei-You; Chang, Kung-Yuan; Chi, Lifeng

2013-01-01

Highlights: ► The structural and sensing properties of Gd 2 Ti 2 O 7 , Er 2 TiO 5 and Lu 2 Ti 2 O 7 sensing films grown on Si substrates by reactive co-sputtering. ► The EIS device incorporating a Lu 2 Ti 2 O 7 sensing film exhibited a higher sensitivity, a larger drift rate, a higher hysteresis voltage, and a larger hysteresis gap than other sensing films. ► The impedance effect of EIS sensors has been investigated using C–V method. -- Abstract: This paper describes the structural and sensing characteristics of Gd 2 Ti 2 O 7 , Er 2 TiO 5 , and Lu 2 Ti 2 O 7 sensing membranes deposited on Si substrates through reactive co-sputtering for electrolyte–insulator–semiconductor (EIS) pH sensors. In this work, the structural properties of Gd 2 Ti 2 O 7 , Er 2 TiO 5 , and Lu 2 Ti 2 O 7 membranes were investigated by X-ray diffraction, atomic force microscopy and X-ray photoelectron spectroscopy. The observed structural properties were then correlated with the resulting pH sensing performances. The EIS device incorporating a Lu 2 Ti 2 O 7 sensing film exhibited a higher sensitivity (59.32 mV pH −1 ), a larger drift rate (0.55 mV h −1 ), a higher hysteresis voltage (5 mV), and a larger hysteresis gap (∼70 mV) compared to those of the other sensing films. This result is attributed to the higher surface roughness and the formation of a thicker interfacial layer at the oxide–Si interface. Furthermore, the impedance effect of EIS sensors has been investigated using capacitance–voltage (C–V) method (frequency-dependent C–V curves). From the impedance spectroscopy analysis, we find that the diameter of a semicircle of an EIS sensor becomes smaller due to a gradual decrease in the bulk resistance of the device with degree of pH value

Kinetics of yttrium dissolution from waste ceramic dust

OpenAIRE

STOPIC SRECKO R.; FRIEDRIH BERND G.

2016-01-01

Yttrium is a silvery transition metal and has similar chemical properties to lanthanoids. Because of this similarity, yttrium belongs to rare earth elements. Ytttrium and yttrium oxide are mostly used in fluoroscent lamps, production of electrodes, in electronic filters, lasers, superconductors and as additives in various materials to improve their properties. Yttrium is mainly recovered from the minerals monazite [(Ce,La,Th,Nd,Y)PO4] and xenotime YPO4.The presence of radioactive elements suc...

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

International Nuclear Information System (INIS)

Le Ba Thuan; Pham Quang Trung; Vu Lap Lai

2003-01-01

1. Yenphu rare earth ore concentrate treatment by alkali under pressure: On the base of studying mineral and chemical compositions of Yenphu rare earth ore concentrate containing 28% TREO and conditions for digestion of ore concentrate by alkali under pressure such as ore concentrate/ NaOH ratio, alkali concentration, pressure and temperature at bench scale (100 gram and 5 kg per batch), the optimal conditions for decomposition of REE ore concentrate have been determined. The yield of the decomposition stage is about 90%. The studies on alkali washing, REE leaching by HCl, pH for leaching process, and iron and radioactive impurities removing by Na 2 S + Na 2 PO 4 have been carried out. The obtained results show that mixture of Na 2 S 5% + Na2PO 4 1% is effective in iron and radioactive impurities removing. The obtained REE oxides get purity of > 99% and meet the need of solvent extraction (SX) individual separation of rare earth elements. The schema for recovery of REEs from Yenphu REE ore concentrate by alkali decomposition under high pressure has been proposed. 2. Fractionation of Yenphu rare earth mixture into subgroups by solvent extraction with PC88A: On the base of simulation program, the parameters for fractional process of rare earths mixture into subgroups by solvent extraction with PC88A have been proposed and determined by experimental verification on mixer-settler set. According to this process, rare earths mixture fractionated into yttrium and light subgroups. In their turn, the light subgroup was separated into light (La, Ce, Pr, Nd) and middle (Sm, Eu, Gd) subgroups. The average yield of the process reached value > 95%. The composition of light subgroup meets the needs for individual separation of Gd, Eu, and Sm. 3. Separation and purification of yttrium: The process for recovery of yttrium consists of two stages: upgrade to get high quality Y concentrate by PC88A and purification by Aliquat 336 in NH 4 SCN-NH 4 Cl medium. The process parameter for

New, dense, and fast scintillators based on rare-earth tantalo-niobates

International Nuclear Information System (INIS)

Voloshyna, O.V.; Boiaryntseva, I.A.; Baumer, V.N.; Ivanov, A.I.; Korjik, M.V.; Sidletskiy, O.Ts.

2014-01-01

Samples of undoped yttrium and gadolinium tantalo-niobates with common formulae RE(Nb x Ta 1−x )O 4 , where RE=Y or Gd and x=0–1, have been obtained by solid-state reaction. Systematic study of structural, luminescent, and scintillation properties of these compounds was carried out. Lattice parameters and space groups of the mixed compounds were identified. UV- and X-ray luminescence spectra, as well as relative light outputs and scintillation decay times are measured. Gadolinium tantalo-niobate with the formulae GdNb 0.2 Ta 0.8 O 4 showed the light output around 13 times larger than PbWO 4 and fast decay with time constant 12 ns without additional slow component. Gadolinium tantalo-niobates may be considered as promising materials for high energy physics due to extremely high density, substantial light output, and fast decay. -- Highlights: •Structural, optical and scintillation properties of the rare earth tantalo-niobates were studied. •Light output shows about gradual increase with Nb content in GdTa x Nb 1−x O 4 . •Light output increases by 2–7 times relatively to yttrium tantalate and niobate in YTa x Nb 1−x O 4 . •GdTa 0.8 Nb 0.2 O 4 demonstrates the most promising scintillation parameters

Fluorimetric determination of yttrium by methyl-bis(8-hydraxy--- 2-quinolyl)amine

International Nuclear Information System (INIS)

Golovina, A.P.; Kachin, S.V.; Runov, V.K.; Fakeeva, O.A.

1982-01-01

Using a method of mathematical Box-Wilson experiment planning the optimum conditions of yttrium fluorimetric determination by methyl-bis (8-hydroxy-2-quinolyl) amine (pH 7.5, csub(R)=1.4x10sup(-5) M) with the determination limit=0.05 μg/ml are found. An extraction-fluorimetric method of yttrium determination by methyl-bis (8-hydroxy-2-quinolyl) amine is developed. The extraction has been realized with aliphatic alcohols at pH > 11. The method is characteristic of the lowest determination limit (0.01 μg/ml) as compared with the known ones. The possibility is shown of yttrium determination in the presence of 5000-multiple aluminium contents, stoichiometric contents of La, Lu, Fe (3), U (6), tartrates, citrates

Adducts of rare earth tris-acetylacetonates with dimethyl sulfoxide

International Nuclear Information System (INIS)

Dzyubenko, N.G.; Kalenichenko, Yu.V.; Martynenko, L.I.

1988-01-01

Adducts of rare earth and yttrium (r.e.e., M) acetylacetonates with dimethyl sulfoxide (DMSO), MA 3 xnDMSO are synthesized. The acetylacetonates of light r.e.e. (M=La-Tb) are shown by different physico-chemical methods to form diadducts of the MA 3 x2DMSOxH 2 O composition, where A - -acetylacetonate-ion, and the acetyl-acetonates of heavy r.e.e. (M=Dy-Lu, Y)-monoadducts MA 3 xDMSO. The estimation of adduct thermal stability is carried out using the values of seeming activation energy of their thermal degradation. Monoadducts are shown to give volatile forms of rare earth acetylacetonates during heating in vacuum, and diadducts do not form volatile forms of acetylacetonates

Phase relations in Ca(Sr)MoO4-Ln2(NoO4)3 systems (Ln = Pr-Lu)

International Nuclear Information System (INIS)

Vakalyuk, V.V.; Evdokimov, A.A.; Berezina, T.A.

1982-01-01

Using the methods of X-ray phase and differential thermal analyses phase ratios in the systems Ca(Sr)MoO 4 -Ln 2 (MoO 4 ) 3 at Ln=Pr-Lu are studied and phase diagrams of the systems CaMoO 4 -Ln 2 (MoO 4 ) 3 , for Ln=Nd, Gd, Yb and SrMoO 4 -Sm 2 (MoO 4 ) 3 are built. It is shown that phase ratios in the systems are similar for the following groups of rare earths: Pr-Sm, Eu-Tb, Ho-Lu. In the first group of systems ordered phase over all subsolidus region are formed, in the second one - ordered phases with scheelite-like structure and wide regions of homogeneity on the basis of Ca(Sr)MoO 4 are formed above the temperature of polymorphous transformation of rare earth molybdates, for the third group of systems intermediate compounds are not detected

Initial stages of ion beam-induced phase transformations in Gd2O3 and Lu2O3

Science.gov (United States)

Chen, Chien-Hung; Tracy, Cameron L.; Wang, Chenxu; Lang, Maik; Ewing, Rodney C.

2018-02-01

The atomic-scale evolution of lanthanide sesquioxides Gd2O3 and Lu2O3 irradiated with 1 MeV Kr ions at room temperature and 120 K, up to fluences of 1 × 1016 ions/cm2 (˜20 dpa), has been characterized by in situ transmission electron microscopy. At room temperature, both oxides exhibited high radiation tolerance. Irradiation did not cause any observable structural change in either material, likely due to the mobility of irradiation-induced point defects, causing efficient defect annihilation. For Gd2O3, having the larger cation ionic radius of the two materials, an irradiation-induced stacking fault structure appeared at low fluences in the low temperature irradiation. As compared with the cubic-to-monoclinic phase transformations known to result from higher energy (˜GeV) ion irradiation, Kr ions of lower energies (˜MeV) yield much lower rates of damage accumulation and thus less extensive structural modification. At a fluence of 2.5 × 1015 ions/cm2, only the initial stages of the cubic-to-monoclinic (C to B) phase transformation process, consisting of the formation and aggregation of defects, have been observed.

Evidence of dilute ferromagnetism in rare-earth doped yttrium aluminium garnet

Energy Technology Data Exchange (ETDEWEB)

Farr, Warrick G.; Goryachev, Maxim; Le Floch, Jean-Michel; Tobar, Michael E. [ARC Centre of Excellence for Engineered Quantum Systems, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009 (Australia); Bushev, Pavel [Experimentalphysik, Universität des Saarlandes, D-66123 Saarbrücken (Germany)

2015-09-21

This work demonstrates strong coupling regime between an erbium ion spin ensemble and microwave hybrid cavity-whispering gallery modes in a yttrium aluminium garnet dielectric crystal. Coupling strengths of 220 MHz and mode quality factors in excess of 10{sup 6} are demonstrated. Moreover, the magnetic response of high-Q modes demonstrates behaviour which is unusual for paramagnetic systems. This behaviour includes hysteresis and memory effects. Such qualitative change of the system's magnetic field response is interpreted as a phase transition of rare earth ion impurities. This phenomenon is similar to the phenomenon of dilute ferromagnetism in semiconductors. The clear temperature dependence of the phenomenon is demonstrated.

Hyperfine fields at some 4d, 5d and 4f impurities in ferromagnetic GdZn and GdCd

International Nuclear Information System (INIS)

Kasamatsu, Y.; Kojima, K.; Hihara, T.

1995-01-01

Hyperfine (hf) fields at 4d (Y, Nb, Rh, Pd), 5d (Lu, Ta, Ir) and 4f (La, Nd, Sm, Eu) impurities in ferromagnetic GdZn and GdCd have been measured by NMR at 4.2 K. The local moment contributions to the hf field suggest that the impurity moments at the beginning and end of the d series are parallel and antiparallel to Gd moments, respectively. The hf results for 4f impurities are also discussed. ((orig.))

Complexing in aqueous solutions of rare earth n-aminobenzoates

International Nuclear Information System (INIS)

Efremova, G.I.; Buchkova, R.T.; Lapitskaya, A.V.; Pirkes, S.B.

1977-01-01

Complexing in the system ''ion of a rare-earth metal - n-aminobenzoic acid'' has been investigated by the pH-metric method in the pH range of 3.5-5.5. In the La-Eu series, the stability of n-aminobenzoate complexes increases and attains the maximum value in the complex Eu (lg Ksub(st)=2.66). In the Gd-Lu series the stability of the complex particles decreases monotonically

Comparison of solidification temperatures of different rare earth sesquioxides; effect of atmosphere

International Nuclear Information System (INIS)

Coutures, J.-P.; Verges, R.; Foex, M.

1975-01-01

The measurement of the solidification point of the rare earth sesquioxides shows anomalies for La 2 O 3 , Gd 2 O 3 , Lu 2 O 3 and allows to find the well known ceric group and yttric group. The effects of the atmosphere on the refractory character are generally low. An interpretation in order to explain the observed changes, is proposed [fr

Phase transition control, melt growth of (Gd,RE)F{sub 3} single crystal and their luminescent properties

Energy Technology Data Exchange (ETDEWEB)

Yoshikawa, Akira, E-mail: yosikawa@tagen.tohoku.ac.j [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Jouini, Anis [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); BerlinSolar GmbH, Magnusstrasse 11, D-12489 Berlin (Germany); Kamada, Kei [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Boulon, Georges [Physical Chemistry of Luminescent Materials, Claude Bernard/Lyon 1 University, UMR 5620 CNRS, Villeurbanne (France); Nikl, Martin [Institute of Physics AS CR, Cukrovarnicka 10, Prague 16253 (Czech Republic); Saito, Fumio [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

2009-12-15

Rare-earth sesquifluorides with no absorption in visible spectral region, such as LaF{sub 3}, GdF{sub 3}, LuF{sub 3}, YF{sub 3}, ScF{sub 3}, are the topic of intense study as a host for luminescence materials. However, except Nd:LaF{sub 3}, they are not studied as a host for laser materials. The main obstacle troubling further study of GdF{sub 3}, LuF{sub 3}, YF{sub 3}, ScF{sub 3} single crystal is the fact that there is first-order phase transition (LaF{sub 3} type{leftrightarrow}{beta}-YF{sub 3} type for GdF{sub 3}, {alpha}-YF{sub 3} type{leftrightarrow}{beta}-YF{sub 3} type for the rest) between the room and melting temperature.To prevent the phase transition, first of all, we have tried to make solid solution between GdF{sub 3} and YF{sub 3} in such a way that the average cation radii can be shifted to the size that does not have phase transition. Ce{sup 3+} perturbed luminescence was observed in the Ce- and Sr-codoped GdF{sub 3}-YF{sub 3} system. Similar solid solution concept was applied to the combination between GdF{sub 3} and YbF{sub 3}. The emission spectrum of Yb{sup 3+} that exhibits broad bands around 1 {mu}m was observed. Room temperature up-conversion luminescence spectra of Pr{sup 3+}-doped Gd{sub 1-x}Yb{sub x}F{sub 3} were studied and visible emission from Pr{sup 3+} was obtained under infrared laser pumping in the Yb{sup 3+} broad absorption band at 935.5 nm.

The isolation of lutetium from gadolinium contained in Purex process solutions

International Nuclear Information System (INIS)

Bostick, D.T.; Vick, D.O.; May, M.P.; Walker, R.L.

1992-09-01

A chemical separation procedure has been devised to isolate Lu from Purex dissolver solutions containing the neutron poison, Gd. The isolation procedure involves the removal of U and >Pu from a dissolver solution using tributylphosphate solvent extraction. If required, solvent extraction using di-(2-ethylhexyl) phosphoric acid can be employed to further purify the sample be removing alkali and alkali earth elements. Finally, Lu is chromatographically separated from Gd and rare earth fission products on a Dowex 50W-X8 resin column using an alpha-hydroxyisobutyrate eluant. The success of the chemical separation procedure has been demonstrated in the quantitative recovery of as little as 1.4 ng Lu from solutions containing a 5000-fold excess of Gd. Additionally, Lu has been isolated from synthetic dissolver samples containing U, Ba, Cs, and Gd. Thermal emission MS data indicated that the Lu fraction of the synthetic sample was free of Gd interference

Crystal growth and characterization of Tm doped mixed rare-earth aluminum perovskite

Energy Technology Data Exchange (ETDEWEB)

Totsuka, Daisuke, E-mail: totsuka@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Nihon Kessho Kogaku Co., Ltd., 810-5 Nobe-cho, Tatebayashi, Gunma 374-0047 (Japan); Yanagida, Takayuki [New Industry Creation Hatchery Center (NICHe), 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Sugiyama, Makoto; Fujimoto, Yutaka; Yokota, Yuui [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Yoshikawa, Akira [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan)

2012-04-15

Highlights: Black-Right-Pointing-Pointer (Lu{sub x}Gd{sub y}Y{sub 0.99-x-y}Tm{sub 0.01})AP single crystals were grown by the {mu}-PD method. Black-Right-Pointing-Pointer The grown crystals were single phase with perovskite structure (Pbnm). Significant segregation of Lu and Gd was detected in the growth direction. Black-Right-Pointing-Pointer Some absorption bands due to Tm{sup 3+}, Gd{sup 3+} and color centers were exhibited. Black-Right-Pointing-Pointer Radioluminescence spectra showed several emission peaks ascribed to Tm{sup 3+} and Gd{sup 3+}. -- Abstract: In this work, we present results of structural characterization and optical properties including radio luminescence of (Lu{sub x}Gd{sub y}Y{sub 0.99-x-y}Tm{sub 0.01})AP single crystal scintillators for (x, y) = (0.30, 0.19), (0, 0.19) and (0, 0) grown by the micro-pulling-down ({mu}-PD) method. The grown crystals were single phase materials with perovskite structure (Pbnm) as confirmed by XRD and had a good crystallinity. The distribution of the crystal constituents in growth direction was evaluated, and significant segregation of Lu and Gd was detected in (Lu{sub 0.30}Gd{sub 0.19}Y{sub 0.50}Tm{sub 0.01})AP sample. The crystals demonstrated 70% transmittance in visible wavelength range and some absorption bands due to Tm{sup 3+}, Gd{sup 3+} and color centers were exhibited in 190-900 nm. The radioluminescence measurement under X-ray irradiation demonstrated several emission peaks ascribed to 4f-4f transitions of Tm{sup 3+} and Gd{sup 3+}. The ratio of emission intensity in longer wavelength range was increased when Y was replaced by Lu or Gd.

Phase stabilization in transparent Lu2O3:Eu ceramics by lattice expansion

Science.gov (United States)

Seeley, Z. M.; Dai, Z. R.; Kuntz, J. D.; Cherepy, N. J.; Payne, S. A.

2012-11-01

Gadolinium lutetium oxide transparent ceramics doped with europium (Gd,Lu)2O3:Eu were fabricated via vacuum sintering and hot isostatic pressing (HIP). Nano-scale starting powder with the composition GdxLu1.9-xEu0.1O3 (x = 0, 0.3, 0.6, 0.9, 1.0, and 1.1) were uniaxially pressed and sintered under high vacuum at 1625 °C to obtain ˜97% dense structures with closed porosity. Sintered compacts were then subjected to 200 MPa argon gas at temperatures between 1750 and 1900 °C to reach full density. It was observed that a small portion of the Eu3+ ions were exsolved from the Lu2O3 cubic crystal lattice and concentrated at the grain boundaries, where they precipitated into a secondary monoclinic phase creating optical scattering defects. Addition of Gd3+ ions into the Lu2O3 cubic lattice formed the solid solution (Gd,Lu)2O3:Eu and stretched the lattice parameter allowing the larger Eu3+ ions to stay in solid solution, reducing the secondary phase and improving the transparency of the ceramics. Excess gadolinium, however, resulted in a complete phase transformation to monoclinic at pressures and temperatures sufficient for densification. Light yield performance was measured and all samples show equal amounts of the characteristic Eu3+ luminescence, indicating gadolinium addition had no adverse effect. This material has potential to improve the performance of high energy radiography devices.

Hydrothermal synthesis, characterization and up/down-conversion luminescence of barium rare earth fluoride nanocrystals

International Nuclear Information System (INIS)

Jia, Li-Ping; Zhang, Qiang; Yan, Bing

2014-01-01

Graphical abstract: Lanthanide ions doped bare earth rare earth fluoride nanocrystals are synthesized by hydrothermal technology and characterized. The down/up-conversion luminescence of them are discussed. - Highlights: • Mixed hydrothermal system H 2 O–OA (EDA)–O-A(LO-A) is used for synthesis. • Barium rare earth fluoride nanocrystals are synthesized comprehensively. • Luminescence for down-conversion and up-conversion are obtained for these systems. - Abstract: Mixed hydrothermal system H 2 O–OA (EDA)–O-A(LO-A) is developed to synthesize barium rare earth fluorides nanocrystals (OA = oleylamine, EDA = ethylenediamine, O-A = oleic acid and LO-A = linoleic acid). They are presented as BaREF 5 (RE = Ce, Pr, Nd, Eu, Gd, Tb, Dy, Y, Tm, Lu) and Ba 2 REF 7 (RE = La, Sm, Ho, Er, Yb). The influence of reaction parameters (rare earth species, hydrothermal system and temperature) is checked on the phase and shape evolution of the fluoride nanocrystals. It is found that reaction time and temperature of these nanocrystals using EDA (180 °C, 6 h) is lower than those of them using OA (220 °C, 10 h). The photoluminescence properties of these fluorides activated by some rare earth ions (Nd 3+ , Eu 3+ , Tb 3+ ) are studied, and especially up-conversion luminescence of the four fluoride nanocrystal systems (Ba 2 LaF 7 :Yb, Tm(Er), Ba 2 REF 7 :Yb, Tm(Er) (RE = Gd, Y, Lu)) is observed

Rare earth-transition metal indides with Lu{sub 5}Ni{sub 2}In{sub 4}-type structure

Energy Technology Data Exchange (ETDEWEB)

Zaremba, Roman; Hermes, Wilfried; Eul, Matthias; Poettgen, Rainer [Inst. fuer Anorganische und Analytische Chemie, Univ. Muenster (Germany)

2008-12-15

New intermetallic compounds RE{sub 5}T{sub 2}In{sub 4} (RE = Sc, Y, La-Nd, Sm, Gd-Tm, Lu; T = Rh, Ir) were synthesized by arc-melting of the elements or by induction melting of the elements in tantalum crucibles under flowing argon. The samples were characterized by X-ray powder diffraction. They crystallize with the orthorhombic Lu{sub 5}Ni{sub 2}In{sub 4}-type structure, space group Pbam, Z = 2, a 2: 1 intergrowth variant of CsCl and AlB{sub 2} related slabs of compositions InRE{sub 8} (distorted cubes) and RhRE{sub 6} (distorted trigonal prisms). Susceptibility measurements of Ce{sub 5}Ir{sub 2}In{sub 4} have revealed modified Curie-Weiss behavior above 70 K with an experimental magnetic moment of 2.45(1) {mu}{sub B} / Ce atom. The cerium magnetic moments order ferri- or ferromagnetically at T{sub C} = 7.1(2) K. (orig.)

Peculiarities of component interaction in {l_brace}Gd, Er{r_brace}-V-Sn Ternary systems at 870 K and crystal structure of RV{sub 6}Sn{sub 6} stannides

Energy Technology Data Exchange (ETDEWEB)

Romaka, L., E-mail: romakal@franko.lviv.ua [Inorganic Chemistry Department, Ivan Franko Lviv National University, Kyryla and Mefodiya str. 6, 79005 Lviv (Ukraine); Stadnyk, Yu. [Inorganic Chemistry Department, Ivan Franko Lviv National University, Kyryla and Mefodiya str. 6, 79005 Lviv (Ukraine); Romaka, V.V. [Department of Materials Engineering and Applied Physics, Lviv Polytechnic National University, Ustyyanovycha Str. 5, 79013 Lviv (Ukraine); Demchenko, P.; Stadnyshyn, M.; Konyk, M. [Inorganic Chemistry Department, Ivan Franko Lviv National University, Kyryla and Mefodiya str. 6, 79005 Lviv (Ukraine)

2011-09-08

Highlights: > {l_brace}Gd, Er{r_brace}-V-Sn ternary systems at 870 K are characterized by formation of stannides with general compositions RV{sub 6}Sn{sub 6}. > Isostructural RV{sub 6}Sn{sub 6} compounds were also found with Y, Dy, Ho, Tm, and Lu. > The crystal structure of RV{sub 6}Sn{sub 6} compounds was determined by powder diffraction method. > Structural analysis showed that RV{sub 6}Sn{sub 6} compounds (R = Gd, Dy-Tm, Lu) are disordered; YV{sub 6}Sn{sub 6} is characterized by structure ordering. - Abstract: The phase equilibria in the Gd-V-Sn and Er-V-Sn ternary systems were studied at 870 K by means of X-ray and metallographic analyses in the whole concentration range. Both Gd-V-Sn and Er-V-Sn systems are characterized by formation of one ternary compound at investigated temperature, with stoichiometry RV{sub 6}Sn{sub 6} (SmMn{sub 6}Sn{sub 6}-type, space group P6/mmm, a = 0.55322(3) nm, c = 0.91949(7) nm for Gd, a = 0.55191(2) nm, c = 0.91869(8) nm for Er). Solubility of the third component in the binary compounds was not observed. Compounds with the SmMn{sub 6}Sn{sub 6}-type were also found with Dy, Ho, Tm, and Lu, while YV{sub 6}Sn{sub 6} compound crystallizes in HfFe{sub 6}Ge{sub 6} structure type. All investigated compounds are the first ternary stannides with rare earth elements and vanadium.

Isopiestic determination of the activity coefficients of some aqueous rare earth electrolyte solutions at 250C. I. The rare earth chlorides

International Nuclear Information System (INIS)

Spedding, F.H.; Weber, H.O.; Saeger, V.W.; Petheram, H.H.; Rard, J.A.; Habenschuss, A.

1976-01-01

The osmotic coefficients of the aqueous trichlorides of La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y were determined from 0.1 M to saturation at 25 0 C. Semiempirical least-squares equations were obtained for the osmotic coefficients as a function of molality and these equations were used to calculate water activities and mean molal activity coefficients. The water activities of the light rare earth chlorides at constant molalities are higher than for the heavy rare earths, while the mean molal activity coefficients are larger for the heavy rare earths than for the light ones. The above effects are discussed in terms of changes in the cationic radii and hydration of the rare earth ions

Investigations on the determination of traces of some rare earths (Eu, Sm, Gd, Y) in oxides of rare earths (Y2O3, Sm2O3, Gd2O3) by emission spectrography in d.c. arc

International Nuclear Information System (INIS)

Dittrich, K.; Gajek, M.; Luan, P.

1978-01-01

The evaporation of traces and matrices of rare earth elements was investigated in different atmospheres. It was found, that low-boiling rare earths elements, because of their extended formation of carbides evaporate more slowly than high-boiling rare earths elements. The evaporation of the traces depends on the matrices. 3 cases for the determination of traces of rare earths elements in oxides of other rare earths elements are derived from the results of the evaporation: Low- to high-boiling traces of rare earths elements in low-boiling matrices of rare earths elements, low-boiling traces in medium- to high-boiling matrices, and medium- to high-boiling traces in medium- to high-boiling matrices. The results of the determination are: in Y 2 O 3 : 14 ppm Sm, 2 ppm Eu; in Gd 2 O 3 : 18 ppm Y, 3 ppm Sm, 2 ppm Eu; in Sm 2 O 3 : 70 ppm Y, 370 ppm Gd, 16 ppm Eu. (author)

Preclinical evaluation of multistep targeting of diasialoganglioside GD2 using a IgG-scFv bispecific antibody with high affinity for GD2 and DOTA metal complex

Science.gov (United States)

Cheal, Sarah M.; Xu, Hong; Guo, Hong-fen; Zanzonico, Pat B.; Larson, Steven M.; Cheung, Nai-Kong

2014-01-01

Bispecific antibodies (BsAb) have proven to be useful targeting vectors for pretargeted radioimmunotherapy (PRIT). We sought to overcome key PRIT limitations such as high renal radiation exposure and immunogenicity (e.g. of streptavidin-antibody fusions), to advance clinical translation of this PRIT strategy for diasialoganglioside GD2-positive (GD2(+)) tumors. For this purpose, a IgG-scFv BsAb was engineered using the sequences for the anti-GD2 humanized monoclonal antibody hu3F8 (1) and C825, a murine scFv antibody with high affinity for the chelator 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) complexed with beta-particle emitting radiometals such as 177Lu and 90Y (2, 3). A three-step regimen including hu3F8-C825, a dextran-based clearing agent, and p-aminobenzyl-DOTA radiolabeled with 177Lu (as 177Lu-DOTA-Bn; t1/2 = 6.71 days (d)) was optimized in immunocompromised mice carrying subcutaneous (s.c.) human GD2(+) neuroblastoma (NB) xenografts. Absorbed doses for tumor and normal tissues were ∼85 cGy/MBq and ≤3.7 cGy/MBq, respectively, with therapeutic indicies (TI) of 142 for blood and 23 for kidney. A therapy study (n = 5 per group; tumor volume: 240 ± 160 mm3) with three successive PRIT cycles (total 177Lu: ∼33 MBq; tumor dose ∼3400 cGy), revealed complete tumor response in 5/5 animals, with no recurrence up to 28 d post-treatment. Tumor ablation was confirmed histologically in 4/5 mice, and normal organs showed minimal overall toxicities. All non-treated mice required sacrifice within 12 d (>1.0 cm3 tumor volume). We conclude that this novel anti-GD2 PRIT approach has sufficient TI to successfully ablate s.c. GD2(+)–NB in mice while sparing kidney and bone marrow. PMID:24944121

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

International Nuclear Information System (INIS)

Touborg, P.

1977-01-01

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

Growth of rare-earth doped single crystal yttrium aluminum garnet fibers

Science.gov (United States)

Bera, Subhabrata; Nie, Craig D.; Harrington, James A.; Cheng, Long; Rand, Stephen C.; Li, Yuan; Johnson, Eric G.

2018-02-01

Rare-earth doped single crystal (SC) yttrium aluminum garnet (YAG) fibers have great potential as high-power laser gain media. SC fibers combine the superior material properties of crystals with the advantages of a fiber geometry. Improving processing techniques, growth of low-loss YAG SC fibers have been reported. A low-cost technique that allows for the growth of optical quality Ho:YAG single crystal (SC) fibers with different dopant concentrations have been developed and discussed. This technique is a low-cost sol-gel based method which offers greater flexibility in terms of dopant concentration. Self-segregation of Nd ions in YAG SC fibers have been observed. Such a phenomenon can be utilized to fabricate monolithic SC fibers with graded index.

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

International Nuclear Information System (INIS)

Sun Xiaobo; Zhao Junmei; Meng Shulan; Li Deqian

2005-01-01

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

Compounds of addition between yttrium and rare-earths (III) nitrates and the N,N,N'N'-tetramethyladipamide (TMAA)

International Nuclear Information System (INIS)

Lima, W.N. de.

1974-01-01

The synthesis of addition compounds between hydrated rare-earths and yttrium nitrates with the diamine N,N,N',N'-tetramethyladipamide (TMAA) in ethanol, is described. The compounds were characterized by elemental analisys, infrared, Raman, visible and near infrared spectra, molar conductance and molecular weight measurements, conductometric titrations and X-ray powder patterns. (Author) [pt

Effect of rare-earth composition on microstructure and pinning properties of Zr-doped (Gd,Y)Ba2Cu3Ox superconducting tapes

International Nuclear Information System (INIS)

Selvamanickam, V; Zhang, Y; Guevara, A; Shi, T; Yao, Y; Majkic, G; Galtsyan, E; Chen, Y; Lei, C; Miller, D J

2012-01-01

The effect of changing Gd + Y content from 1.2 to 1.6 in the precursor of (Gd,Y)Ba 2 Cu 3 O 7 superconducting thin film tapes made by metal organic chemical vapor deposition (MOCVD) at a constant Gd:Y ratio and a fixed Zr content of 7.5% has been studied. The influence of changing the Gd:Y ratio from Gd = 0 to Y= 0 in 0.2 mol steps at a constant Gd + Y content of 1.2 in the precursor has also been investigated at a fixed Zr content of 7.5%. The critical current of these films is found to vary significantly as a function of rare-earth content as well as a function of rare-earth type. Even for a fixed Zr content, it is found that the critical current in the orientation of magnetic field parallel to the a–b plane and that in the orientation of field perpendicular to the a–b plane can be systematically varied with changing Gd + Y content as well as with changing Gd:Y ratio. The nanoscale defect structures along the a–b plane and along the c-axis are found to be sensitive to these changes in rare-earth content and type. (paper)

Modifying the size and uniformity of upconversion Yb/Er:NaGdF4 nanocrystals through alkaline-earth doping.

Science.gov (United States)

Lei, Lei; Chen, Daqin; Huang, Ping; Xu, Ju; Zhang, Rui; Wang, Yuansheng

2013-11-21

NaGdF4 is regarded as an ideal upconversion (UC) host material for lanthanide (Ln(3+)) activators because of its unique crystal structure, high Ln(3+) solubility, low phonon energy and high photochemical stability, and Ln(3+)-doped NaGdF4 UC nanocrystals (NCs) have been widely investigated as bio-imaging and magnetic resonance imaging agents recently. To realize their practical applications, controlling the size and uniformity of the monodisperse Ln(3+)-doped NaGdF4 UC NCs is highly desired. Unlike the routine routes by finely adjusting the multiple experimental parameters, herein we provide a facile and straightforward strategy to modify the size and uniformity of NaGdF4 NCs via alkaline-earth doping for the first time. With the increase of alkaline-earth doping content, the size of NaGdF4 NCs increases gradually, while the size-uniformity is still retained. We attribute this "focusing" of size distribution to the diffusion controlled growth of NaGdF4 NCs induced by alkaline-earth doping. Importantly, adopting the Ca(2+)-doped Yb/Er:NaGdF4 NCs as cores, the complete Ca/Yb/Er:NaGdF4@NaYF4 core-shell particles with excellent size-uniformity can be easily achieved. However, when taking the Yb/Er:NaGdF4 NCs without Ca(2+) doping as cores, they could not be perfectly covered by NaYF4 shells, and the obtained products are non-uniform in size. As a result, the UC emission intensity of the complete core-shell NCs increases by about 30 times in comparison with that of the cores, owing to the effective surface passivation of the Ca(2+)-doped cores and therefore protection of Er(3+) in the cores from the non-radiative decay caused by surface defects, whereas the UC intensity of the incomplete core-shell NCs is enhanced by only 3 times.

Influence of rare-earth ions on fluorogallate glass formation and properties

International Nuclear Information System (INIS)

Zhang Guoyin; Poulain, M.J.

1998-01-01

Various rare earths have been incorporated in a lead fluorogallate glass with the following chemical composition: 30PbF 2 -20GaF 3 -15InF 3 -20CdF 2 -15ZnF 2 (PGICZ). Selected rare earths are La, Ce, Pr, Nd, Gd, Er, Yb and Lu, and the doping level varies between 1 and 10 mol%. The influence of rare earth fluorides on glass forming ability and on physical properties is investigated. At low concentration ( 3 in a modified PGCIZ glass have been cast. Experimental results suggest that rare earths act as modifiers rather than vitrifies in this fluorogallate system. The effect of rare earths on the values of glass transition temperature, refractive index, density and thermal expansion is reported. (orig.)

Rotating disk atomization of Gd and Gd-Y for hydrogen liquefaction via magnetocaloric cooling

Energy Technology Data Exchange (ETDEWEB)

Slinger, Tyler [Iowa State Univ., Ames, IA (United States)

2016-12-17

In order to enable liquid hydrogen fuel cell technologies for vehicles the cost of hydrogen liquefaction should be lowered. The current method of hydrogen liquefaction is the Claude cycle that has a figure of merit (FOM) of 0.3-0.35. New magnetocaloric hydrogen liquefaction devices have been proposed with a FOM>0.5, which is a significant improvement. A significant hurdle to realizing these devices is the synthesis of spherical rare earth based alloy powders of 200μm in diameter. In this study a centrifugal atomization method that used a rotating disk with a rotating oil quench bath was developed to make gadolinium and gadolinium-yttrium spheres. The composition of the spherical powders included pure Gd and Gd_0.91Y_0.09. The effect of atomization parameters, such as superheat, melt properties, disk shape, disk speed, and melt system materials and design, were investigated on the size distribution and morphology of the resulting spheres. The carbon, nitrogen, and oxygen impurity levels also were analyzed and compared with the magnetic performance of the alloys. The magnetic properties of the charge material as well as the resulting powders were measured using a vibrating sample magnetometer. The saturation magnetization and Curie temperature were the target properties for the resulting spheres. These values were compared with measurements taken on the charge material in order to investigate the effect of atomization processing on the alloys.

Direct quantification of thorium, uranium and rare earth element concentration in natural waters by ICP-MS

International Nuclear Information System (INIS)

Palmieri, Helena E.L.; Knupp, Eliana A.N.; Auler, Lucia M.L.A.; Gomes, Luiza M.F.; Windmoeller, Claudia C.

2011-01-01

A direct quantification of the thorium, uranium and rare earth elements in natural water samples using inductively coupled plasma mass spectrometry (ICP-MS) was evaluated with respect to selection of isotopes, detection limits, accuracy, precision, matrix effects for each isotope and spectral interferences. Accuracy of the method was evaluated by analysis of Spectra pure Standards (SPS-SW1 Batch 116-Norway) for the rare earth elements (REEs), thorium, uranium, scandium and yttrium. The measurements were carried out for each of the following analytical isotopes: 139 La, 140 Ce, 141 Pr, 143 Nd, 147 Sm, 151 Eu, 160 Gd, 159 Tb, 163 Dy, 165 Ho, 167 Er, 16 9Tm, 174 Yb, 175 Lu, 45 Sc, 89 Y, 232 Th and 238 U. Recovery percentage values found in these certified samples varied between 95 and 107%. The method was applied to the analysis of spring water samples collected in fountains spread throughout the historical towns of Ouro Preto, Mariana, Sabara and Diamantina in the state of Minas Gerais, Brazil. In the past these fountains played an essential and strategic role in supplying these towns with potable water. Until today this water is used by both the local population and tourists who believe in its quality. REE were quantified at levels comparable to those found in estuarine waters, which are characterized by low REE concentrations. In two fountains analyzed the concentration of REEs presented high levels and thus possible health risks for humans may not be excluded. (author)

Scintillation properties of a La,Lu-admix gadolinium pyrosilicate crystal

Czech Academy of Sciences Publication Activity Database

Kurosawa, S.; Shishido, T.; Suzuki, A.; Sugawara, T.; Nomura, A.; Yubuta, K.; Shoji, Y.; Yokota, Y.; Pejchal, Jan; Ohashi, Y.; Kamada, K.; Yoshikawa, A.

2015-01-01

Roč. 784, Jun (2015), s. 115-118 ISSN 0168-9002 Institutional support: RVO:68378271 Keywords : scintillator * pyrosilicate crystal * Ce-doped (La, Lu, Gd) Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.200, year: 2015

First measurement of the nonlinear coefficient for Gd_1-xLu_x Ca₄O(BO₃)₃ and Gd_1-xSc_xCa₄O(BO₃)₃ crystals

DEFF Research Database (Denmark)

Andersen, Martin Thalbitzer; Mortensen, Jesper Liltorp; Germershausen, Sven

2007-01-01

The effective nonlinear coefficient and temperature acceptance bandwidth of three Lu and Sc co-doped GdCa4O(B03)3 type nonlinear crystals were measured. NCPM for SHG in to the blue-UV spectral region can be obtained by controlling the co-dopant concentration. Measurements were based on intra-cavi...

Phase transitions of rare earth compounds during immobilization by foamed corundum

International Nuclear Information System (INIS)

Potemkina, T.I.; Zakharov, M.A.; Plotnikova, T.E.

1992-01-01

Expansion of work on the environmentally safe handling of radioactive materials has become very important in recent years. The proposed method for immobilizing radionuclides by injection into a porous matrix and subsequent fixation has a definite advantage over other techniques, because of its simplicity and low cost. This raises a number of problems that require careful study. The authors can distinguish the following: choice of porous matrix materials; thermal decomposition of nitrates directly in the matrix itself, which determines the minimum firing temperature; behavior and properties of oxides produced in nitrate decomposition; conditions for compound formation between injected solutions and matrix material; processes occurring during immobilizer storage. The rare earth nitrate series can be divided into two groups on the basis of behavior during thermal decomposition: the elements preceding and following Gd. The first group includes La, Pr, And Eu, for which decomposition begins simultaneously with conclusion of dehydration; the second includes Dy, Tb, and Yb, for which nitrate group decomposition begins before dehydration is complete. The authors utilized DTA, XPA, and IR analysis to study the physicochemical properties of the immobilizer produced by a single impregnation of the foamed corundum with rare earth (La, Eu, Dy, Tb, and Yb) nitrate solutions and subsequent firing at 900 degrees C for 30 min. The choice of these rare earths was dictated by the fact that the Ln 2 O 3 -AlO 3 system can be divided into three groups on the basis of phase ratios: La-Nd, Sm-Eu, and Gd-Lu. Lanthanide monoaluminates are formed in all these groups, and the difference lies in the other reaction products generated: LnAl 11 O 18 for La-Nd, LnAl 11 O 18 and Ln 4 Al 2 O 9 for Sm-Eu, and Ln 4 Al 2 O 9 and Ln 3 Al 5 O 12 for Gd-Lu

Synthesis and luminescence properties of BaTiO3:RE (RE = Gd , Dy ...

Indian Academy of Sciences (India)

thermoluminescence (TL) properties of BaTiO3 samples doped with Gd3+, Dy3+, Tb3+ and Lu3+ were investigated. ... electron microscope using an accelerating voltage of 20 kV. .... doping of 1% mole Gd3+ ion into the BaTiO3 compound.

Growth, spectral properties, and laser demonstration of Nd:(Lu0.5Gd0.5)2SiO5 crystal

International Nuclear Information System (INIS)

Li, D Z; Xu, X D; Wu, F; Xia, C T; Zhang, J; Ma, J; Cong, Z H; Tang, D Y; Zhu, H M; Chen, X Y; Xu, J

2011-01-01

A Nd:(Lu 0.5 Gd 0.5 ) 2 SiO 5 (Nd:LGSO) crystal has been grown by the Czochralski method. The cell parameters were analyzed with X-ray diffraction (XRD). The Judd-Ofelt intensity parameters Ω 2,4,6 were obtained to be 5.37, 1.63, and 5.57×10 -20 cm 2 , respectively. The absorption and emission cross sections and branching ratios were calculated. The Nd:LGSO crystal reveals a broadband emission feature (FWHM = 9.8 nm), which shows potential as gain medium for ultrashort pulse lasers. The radiative and fluorescence lifetimes are 299 and 230 μs, respectively, resulting in a quantum efficiency of 77%. Pumped by a laser diode, the maximum continuous wave (CW) output power of 444 mW and a slope efficiency of 17.7% have been obtained

Growth, spectral properties, and laser demonstration of Nd:(Lu0.5Gd0.5)2SiO5 crystal

Science.gov (United States)

Li, D. Z.; Xu, X. D.; Zhang, J.; Cong, Z. H.; Tang, D. Y.; Ma, J.; Zhu, H. M.; Chen, X. Y.; Wu, F.; Xia, C. T.; Xu, J.

2011-09-01

A Nd:(Lu0.5Gd0.5)2SiO5 (Nd:LGSO) crystal has been grown by the Czochralski method. The cell parameters were analyzed with X-ray diffraction (XRD). The Judd-Ofelt intensity parameters Ω2,4,6 were obtained to be 5.37, 1.63, and 5.57×10-20 cm2, respectively. The absorption and emission cross sections and branching ratios were calculated. The Nd:LGSO crystal reveals a broadband emission feature (FWHM = 9.8 nm), which shows potential as gain medium for ultrashort pulse lasers. The radiative and fluorescence lifetimes are 299 and 230 μs, respectively, resulting in a quantum efficiency of 77%. Pumped by a laser diode, the maximum continuous wave (CW) output power of 444 mW and a slope efficiency of 17.7% have been obtained.

Scintillation properties of a La, Lu-admix gadolinium pyrosilicate crystal

Energy Technology Data Exchange (ETDEWEB)

Kurosawa, Shunsuke, E-mail: kurosawa@imr.tohoku.ac.jp [Institute for Materials Research (IMR), Tohoku University 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe) 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Shishido, Toetsu; Suzuki, Akira; Sugawara, Takamasa; Nomura, Akiko; Yubuta, Kunio [Institute for Materials Research (IMR), Tohoku University 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Shoji, Yasuhiro [Institute for Materials Research (IMR), Tohoku University 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); C& A Corporation, 6-6-40 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Yokota, Yuui [New Industry Creation Hatchery Center (NICHe) 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Pejchal, Jan [New Industry Creation Hatchery Center (NICHe) 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Institute of Physics, AS CR, Cukrovarnická 10, 162 53 Prague (Czech Republic); Ohashi, Yuji [Institute for Materials Research (IMR), Tohoku University 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Kamada, Kei [New Industry Creation Hatchery Center (NICHe) 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); C& A Corporation, 6-6-40 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Yoshikawa, Akira [Institute for Materials Research (IMR), Tohoku University 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe) 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); C& A Corporation, 6-6-40 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8577 (Japan)

2015-06-01

In order to obtain new scintillator with higher effective atomic number, a pyrosilicate crystal with a composition (Ce{sub 0.01}, Gd{sub 0.54}, La{sub 0.25}, Lu{sub 0.20}){sub 2}Si{sub 2}O{sub 7} (Ce:LaLu-GPS) was grown by the floating zone method. Emission wavelengths of this material were at 370 and 390 nm. Gamma-ray-excited pulse height and scintillation decay measurement showed that Ce:LaLu-GPS had a light output of 34,000±2000 photons/MeV, an FWHM energy resolution of 6.9±0.2%, and the decay time components of 59±1 ns (13%) and 570±20 ns (87%)

β-Y(BO{sub 2}){sub 3}. A new member of the β-Ln(BO{sub 2}){sub 3} (Ln = Nd, Sm, Gd-Lu) structure family

Energy Technology Data Exchange (ETDEWEB)

Schmitt, Martin K.; Huppertz, Hubert [Innsbruck Univ. (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie

2017-07-01

β-Y(BO{sub 2}){sub 3} was synthesized in a Walker-type multianvil module at 5.9 GPa/1000 C. The crystal structure has been elucidated through single-crystal X-ray diffraction. β-Y(BO{sub 2}){sub 3} crystallizes in the orthorhombic space group Pnma (no. 62) with the lattice parameters a = 15.886(2), b = 7.3860(6), and c = 12.2119(9) Aa. Its crystal structure will be discussed in the context of the isotypic lanthanide borates β-Ln(BO{sub 2}){sub 3} (Ln = Nd, Sm, Gd-Lu).

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

International Nuclear Information System (INIS)

Sakata, T.; Enomura, A.

1979-01-01

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

Synthesis, crystal structure and photoluminescent properties of Eu{sup 3+} ion-activated R{sub 4}MoO{sub 9} (R = Y, Gd, and Lu)

Energy Technology Data Exchange (ETDEWEB)

Li, Huaiyong [Department of Materials Science and Engineering, Liaocheng University, Liaocheng 252059 (China); Moon, Byung Kee; Choi, Byung Chun [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of); Jeong, Jung Hyun, E-mail: jhjeong@pknu.ac.kr [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of); Yang, Hyun Kyoung [Jeju Global Research Center, Korea Institute of Energy Research, Jeju 695-971 (Korea, Republic of); Jang, Kiwan; Lee, Ho Sueb [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Yi, Soung Soo [Department of Electronic Material Engineering, Silla University, Busan 617-736 (Korea, Republic of)

2013-05-15

Rare earth molybdates R{sub 4}MoO{sub 9} (R = Y, Gd, and Lu) with Eu{sup 3+} ion-doped were synthesized by solid-state reaction. The phase structure, optical absorption and photoluminescence properties of the as-prepared powder samples were studied. The powder X-ray diffraction patterns indicated that all the compounds crystallized in a hexagonal structure, and the lattice parameters reduced in the order of the ionic radii of R. The UV–visible diffuse reflectance spectra revealed that the compounds had a strong absorption of near-UV light due to the excitation of MoO{sub 6} groups in the host lattices. The energy absorbed by the host lattices could then be transferred to doped Eu{sup 3+} ions, resulting in red emission due to the f–f transitions of Eu{sup 3+} ions. The optical absorption and photoluminescence properties of the compounds indicated that they might be candidates as the color-conversion red phosphors for solid-state lighting. - Highlights: ► Structure, optical and photoluminescence properties of Eu{sup 3+} ion-activated R{sub 4}MoO{sub 9} were studied. ► Energy transfer from MoO{sub x} to Eu{sup 3+} can be used to convert near-UV to red light. ► R{sub 4}MoO{sub 9}:Eu might be candidate for color-conversion red phosphors excited by near-UV light.

Yttrium separation of Xenotime waste in Pitinga (Brazil), in order to obtain rare earth elements

International Nuclear Information System (INIS)

Melo.

1996-01-01

The xenotime (YPO 4 and rare earth elements) found in the mine of Pitinga, Amazonas State, Brazil, has its origin in a primal depository ('eluvio' kind) of cassiterite, having considerable quantities of zirconite, ilmenite, topaz and niobates-tantalates. This xenotime has different characteristics in relation of the depositories that exist in other countries for presenting more concentration of rare earth heavy oxides. The mineralization of this cassiterite is problematic, because of the high level of radioactive elements. In the present work, we will process only the xenotime. The separation of rare earth elements is very difficult due to their great chemical similarity. For a more exactly determination, it is necessary to separate them at least of the macron constituents of the sample. As the Yttrium is considerate one of the rare earth elements, due to its chemical similarity, we can understand the difficulty of a chemical separation, mainly when this one is also a macro constituent of the sample, as in the case of xenotime. The process of separation will be based on the little difference that exists between the constants of complexation and the fluoride. (authors). 5 refs., 1 fig., 2 tabs

Effect of rare-earth composition on microstructure and pinning properties of Zr-doped (Gd, Y)Ba{sub 2}Cu{sub 3}O{subx} superconducting tapes.

Energy Technology Data Exchange (ETDEWEB)

Selvamanickam, V.; Chen, Y.; Zhang, Y.; Guevara, A.; Shi, T.; Yao, Y.; Majkic, G.; Lei, C.; Galtsyan, E.; Miller, D. J. (Materials Science Division); (Univ. Houston); (SuperPower Inc.)

2012-01-01

The effect of changing Gd + Y content from 1.2 to 1.6 in the precursor of (Gd,Y)Ba{sub 2}Cu{sub 3}O{sub 7} superconducting thin film tapes made by metal organic chemical vapor deposition (MOCVD) at a constant Gd:Y ratio and a fixed Zr content of 7.5% has been studied. The influence of changing the Gd:Y ratio from Gd = 0 to Y= 0 in 0.2 mol steps at a constant Gd + Y content of 1.2 in the precursor has also been investigated at a fixed Zr content of 7.5%. The critical current of these films is found to vary significantly as a function of rare-earth content as well as a function of rare-earth type. Even for a fixed Zr content, it is found that the critical current in the orientation of magnetic field parallel to the a-b plane and that in the orientation of field perpendicular to the a-b plane can be systematically varied with changing Gd + Y content as well as with changing Gd:Y ratio. The nanoscale defect structures along the a-b plane and along the c-axis are found to be sensitive to these changes in rare-earth content and type.

Ion chromatography separation of lanthanides at trace concentrations from Gd Matrix and quantification by ICP-MS

International Nuclear Information System (INIS)

Raut, V.V.; Jeyakumar, S.; Nagar, B.K.; Deb, S.B.; Saxena, M.K.; Tomar, B.S.

2014-01-01

Gadolinium compounds are mainly used as burnable poison. The presence of certain impurities is undesirable in the nuclear grade Gd compounds. Gd 2 O 3 , a most common raw material used for the preparation of nuclear grade Gd compounds. Analysis of rare earth impurities in Gd-matrices is one of the important exercises carried out to ensure the purity of Gd 2 O 3 . Determination of lanthanides at trace concentrations in lanthanide (Gd) matrix is complicated and difficult to realize. This is because the selective separation of REE's in one of the lanthanide elements is a challenging task. The present study was carried out to explore the feasibility of separating trace level lanthanides from Gd matrix by ion interaction chromatography (IIC) and to develop an analytical methodology for the determination of lanthanides by inductively coupled plasma mass spectrometry (ICP-MS). In the present investigation, the reversed phase column was dynamically modified into sulphonic acid functionalized surface by using 0.025 M n-Octane sulphonic acid (OSA). With α-HIBA eluent system, the elution order follows as Lu to La. The separations are employed with gradient elution mode. Since the sample has large excess of Gd, elution profiles with concentration gradient of HIBA were attempted. Separated fractions of Light lanthanides (LLn) and Heavy lanthanides (HLn) were collected and analyzed by ICP-MS. During MS analysis, it was observed that due to high concentration of salt (Na salt of OSA) present in the collected fractions caused difficulty in ICP-MS . Hence the experiments were carried out using another ion interacting reagent viz. 0.03 M camphor-10-sulphonic acid (CSA). Initial concentration of HIBA was kept at 0.025 M up to 15 min for the elution of HLns i.e. from Lu to Tb and it was then increased to 0.05 M to 0.3 M in 30 min. After elution of Tb, outlet of the column was switched to drain for 7 min to separate bulk Gd fraction. From 22 to 35 min effluent fraction containing Eu

Enhancing photovoltaic performance of dye-sensitized solar cell by rare-earth doped oxide of Lu2O3:(Tm3+, Yb3+)

International Nuclear Information System (INIS)

Li Qingbei; Lin Jianming; Wu Jihuai; Lan Zhang; Wang Yue; Peng Fuguo; Huang Miaoliang

2011-01-01

Highlights: → Tm 3+ /Yb 3+ codoped oxide is introduced into the TiO 2 film in dye-sensitized solar cell. → The RE improves light harvest via conversion luminescence and increases photocurrent. → The RE elevates the oxide film energy level and increases the cell photovoltage. → The cell efficiency is increased by 11.1% compared to the cell lacking of RE doping. - Abstract: In order to increase of the photocurrent, photovoltage and energy conversion efficiency of dye-sensitized solar cell (DSSC), rare-earth doped oxide of Lu 2 O 3 :(Tm 3+ , Yb 3+ ) is prepared and introduced into the TiO 2 film in the DSSC. As a luminescence medium, Lu 2 O 3 :(Tm 3+ , Yb 3+ ) improves incident light harvest via a conversion luminescence process and increases photocurrent; as a p-type dopant, the rare-earth ions elevate the energy level of the oxide film and increase the photovoltage. Under a simulated solar light irradiation of 100 mW cm -2 , the light-to-electric energy conversion efficiency of the DSSC with Lu 2 O 3 :(Tm 3+ , Yb 3+ ) doping reaches 6.63%, which is increased by 11.1% compared to the DSSC without Lu 2 O 3 :(Tm 3+ , Yb 3+ ) doping.

The Gd-Co-Al system at 870/1070 K as a representative of the rare earth-Co-Al family and new rare-earth cobalt aluminides: Crystal structure and magnetic properties

Science.gov (United States)

Morozkin, A. V.; Garshev, A. V.; Knotko, A. V.; Yapaskurt, V. O.; Mozharivskyj, Y.; Yuan, Fang; Yao, Jinlei; Nirmala, R.; Quezado, S.; Malik, S. K.

2018-05-01

The Gd-Co-Al system has been investigated at 870/1070 K by X-ray and elemental EDS analyses. The existence of the known compounds Gd2Co3Al9 (Y2Co3Ga9-type), Gd3Co4.5Al11.5 (Gd3Co4.6Al11) (Gd3Ru4Al12-type), Gd3Co6-7.4Al3-1.6 (CeNi3-type), GdCo1.15-0.65Al0.85-1.35 (MgZn2-type), Gd2Co2Al (Mo2NiB2-type) and Gd3Co3.5-3.25Al0.5-0.75 (W3CoB3-type) has been confirmed at 870/1070 K. Structure types have been determined for Gd2Co6Al19 (U2Co6Al19-type), Gd7Co6Al7 (Pr7Co6Al7-type), Gd6Co2-2.21Al1-0.79 (Ho6Co2Ga-type) and Gd14Co3.2Al2.8 (Gd14Co2.58Al3.42 at 970 K) (Lu14Co3In3-type). The structures of Gd6Co2Al, Gd6Co2.21Al0.79 and Gd14Co2.58Al3.42 flux-grown at 970 K have been refined from the single crystal X-ray diffraction data. Additionally, new ternary compounds Gd2Co5.7-5.3Al1.3-1.7 (Er2Co7-type) and Gd58Co20Al22 (unknown type structure) have been identified. Quasi-binary solid solutions were detected for Gd2Co17, GdCo5, Gd2Co7, GdCo3, GdCo2 and GdAl2 at 870/1070 K, while no appreciable solubility was observed for the other binary compounds in the Gd-Co-Al system. Magnetic properties of the Gd2Co3Al9, Gd3Co4.6Al11, Gd7Co6Al7, Gd6Co2.2Al0.8 and Gd14Co2.58Al3.42 compounds have been studied and are presented in this work. Gd6Co2.2Al0.8, Gd3Co4.6Al11, Gd7Co6Al7 and Gd14Co2.58Al3.42 order ferromagnetically, while Gd2Co3Al9 displays antiferromagnetic transition. Additionally, {Y, Sm, Tb - Tm}2Co6Al19 (U2Co6Al19-type), Yb2Co3Al9 (Y2Co3Ga9-type), {Y, Sm, Tm, Yb}3Co4.6Al11 (Gd3Ru4Al12-type) and Tb7Co6Al7 (Pr7Co6Al7-type) compounds have been synthesized and investigated.

Rare earth sulfates

International Nuclear Information System (INIS)

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

1986-01-01

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

Effect of rare earth element yttrium addition on microstructures and properties of a 21Cr-11Ni austenitic heat-resistant stainless steel

International Nuclear Information System (INIS)

Chen, Lei; Ma, Xiaocong; Wang, Longmei; Ye, Xiaoning

2011-01-01

Research highlights: → Applications of Y in 21Cr-11Ni austenitic heat-resistant stainless steel. → Sensible characteristics of microstructure and properties have been observed. → Y has been found be effective in improving hot ductility of 21Cr-11Ni steel. → Inhibitory effect of Y on S segregation to the grain boundary has been observed. -- Abstract: In this comparative study, the microstructure and the mechanical properties of a 21Cr-11Ni austenitic heat-resistant stainless steel with and without addition of rare earth (RE) element yttrium have been investigated. The results show that a number of fine spherical yttrium-rich oxide particles are not uniformly distributed in the matrix of steel with yttrium; instead, they are aligned along the rolling direction. The grains surrounding the alignment are nearly one order of magnitude smaller than those farther away from the alignment. The approximate calculation results indirectly show that the grain refinement may be mainly attributed to the stimulation for nucleation of recrystallization rather than to pinning by particles. Furthermore, the alignment has resulted in significant loss in transverse impact toughness and tensile elongation at room temperature. There is a trough in the hot ductility-temperature curve, which is located between 973 and 1173 K. The ductility trough of steel with yttrium becomes shallow within a certain temperature range, especially around 1073 K, indicating that improvement on hot ductility is achieved by yttrium addition. The results may be attributed to the increase of grain boundary cohesion indicated by the effective improvement on intergranular failure tendency, and the inhibitory effect of yttrium on sulfur segregation to grain boundaries is believed to be an important cause.

Correlation consistent basis sets for lanthanides: The atoms La–Lu

Energy Technology Data Exchange (ETDEWEB)

Lu, Qing; Peterson, Kirk A., E-mail: kipeters@wsu.edu [Department of Chemistry, Washington State University, Pullman, Washington 99164-4630 (United States)

2016-08-07

Using the 3rd-order Douglas-Kroll-Hess (DKH3) Hamiltonian, all-electron correlation consistent basis sets of double-, triple-, and quadruple-zeta quality have been developed for the lanthanide elements La through Lu. Basis sets designed for the recovery of valence correlation (defined here as 4f5s5p5d6s), cc-pVnZ-DK3, and outer-core correlation (valence + 4s4p4d), cc-pwCVnZ-DK3, are reported (n = D, T, and Q). Systematic convergence of both Hartree-Fock and correlation energies towards their respective complete basis set (CBS) limits are observed. Benchmark calculations of the first three ionization potentials (IPs) of La through Lu are reported at the DKH3 coupled cluster singles and doubles with perturbative triples, CCSD(T), level of theory, including effects of correlation down through the 4s electrons. Spin-orbit coupling is treated at the 2-component HF level. After extrapolation to the CBS limit, the average errors with respect to experiment were just 0.52, 1.14, and 4.24 kcal/mol for the 1st, 2nd, and 3rd IPs, respectively, compared to the average experimental uncertainties of 0.03, 1.78, and 2.65 kcal/mol, respectively. The new basis sets are also used in CCSD(T) benchmark calculations of the equilibrium geometries, atomization energies, and heats of formation for Gd{sub 2}, GdF, and GdF{sub 3}. Except for the equilibrium geometry and harmonic frequency of GdF, which are accurately known from experiment, all other calculated quantities represent significant improvements compared to the existing experimental quantities. With estimated uncertainties of about ±3 kcal/mol, the 0 K atomization energies (298 K heats of formation) are calculated to be (all in kcal/mol): 33.2 (160.1) for Gd{sub 2}, 151.7 (−36.6) for GdF, and 447.1 (−295.2) for GdF{sub 3}.

Obtainment of zirconium oxide and partially stabilized zirconium oxide with yttrium and rare earth oxides, from Brazilian zirconite, for ceramic aim

International Nuclear Information System (INIS)

Ribeiro, S.

1991-05-01

This work presents experimental results for processing of brazilian zirconite in order to obtain zirconium oxide with Yttrium and Rare Earth oxide by mutual coprecipitation for ceramics purposes. Due to analysis of experimental results was possible to obtain the optimum conditions for each one of technological route stage, such as: alkaline fusion; acid leaching; sulfactation and coprecipitation. (author)

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-06-15

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

Ion irradiation of rare-earth- and yttrium-titanate-pyrochlores

International Nuclear Information System (INIS)

Wang, S.X.; Wang, L.M.; Ewing, R.C.; Govindan Kutty, K.V.

2000-01-01

Pyrochlore, A 1-2 B 2 O 6 (O,OH,F) 0-1 , is an actinide-bearing phase in Synroc, a polyphase ceramic proposed for the immobilization of high level nuclear waste. Structural damage due to alpha-decay events can significantly affect the chemical and physical stability of the nuclear waste form. Pyrochlore can effectively incorporate a variety of actinides into its structure. Four titanate pyrochlores were synthesized with compositions of Gd 2 Ti 2 O 7 , Sm 2 Ti 2 O 7 , Eu 2 Ti 2 O 7 and Y 2 Ti 2 O 2 . These samples were irradiated with 1 MeV Kr + in order to simulate alpha-decay damage and were observed by in situ electron microscopy. Irradiations were conducted from 25 K to 1023 K. At room temperature, Gd-, Sm- and Eu-pyrochlores amorphized at a dose of ∼2x10 14 ions/cm 2 (∼0.5 dpa) and Y-pyrochlore amorphized at 4x10 14 ions/cm 2 (∼0.8 dpa). The amorphization dose became higher at elevated temperatures with different rates of increase for each composition. The critical temperatures for amorphization are ∼1100 K for Gd-, Sm-, Eu-pyrochlore and ∼780 K for Y-pyrochlore. The rare-earth-pyrochlores are more susceptible to amorphization and have higher critical temperatures than Y-pyrochlore. The difference in amorphization dose and critical temperature is attributed to the different cascade sizes caused by the different cation masses of the target. Based on a model of cascade quenching, the larger cascade is related to a lower amorphization dose and higher critical temperature. The irradiated materials were studied by electron diffraction and high-resolution electron microscopy. All the pyrochlores transformed to a fluorite substructure prior to the completion of amorphization of the observed regions. This transformation was caused by the disordering between cations and between oxygen and oxygen vacancies. The concurrence of cation disordering with amorphization suggests the partial recrystallization of the displacement cascades. Isolated cascade damage

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

International Nuclear Information System (INIS)

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

1997-01-01

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

Optimization Recovery of Yttrium Oxide in Precipitation, Extraction, and Stripping Process

Science.gov (United States)

Perwira, N. I.; Basuki, K. T.; Biyantoro, D.; Effendy, N.

2018-04-01

Yttrium oxide can be used as a dopant control rod of nuclear reactors in YSH material and superconductors. Yttrium oxide is obtained in the Xenotime mineral derived from byproduct of tin mining PT Timah Bangka which contain rare earth elements (REE) dominant Y, Dy, and Gd whose content respectively about 29.53%, 7.76%, and 2.58%. Both usage in the field of nuclear and non-nuclear science and technology is need to pure from the impurities. The presence of impurities in the yttrium oxide may affect the characteristic of the material and the efficiency of its use. Thus it needs to be separated by precipitation and extraction-stripping and calcination in the making of the oxide. However, to obtain higher levels of Yttrium oxide, it is necessary to determine the optimum conditions for its separation. The purpose of this research was to determine the optimum pH of precipitation, determine acid media and concentration optimum in extraction and stripping process and determine the efficiency of the separation of Y from REE concentrate. This research was conducted with pH variation in the precipitation process that pHs were 4 - 8, the difference of acid media for the extraction process, i.e., HNO3, HCl and H2SO4 with each concentration of 0,5 M; 1 M; 1,5 M; and 2 M and for stripping process were HNO3, HCl, and H2SO4 with each concentration of 1 M; 2M; and 3 M. Based on the result, the optimum pH of precipitation process was 6,5, the optimumacid media was HNO3 0,5 M, and for stripping process media was HNO3 3 M. The efficiency of precipitation process at pH 6,5 was 69,53 %, extraction process was 96.39% and stripping process was 4,50%. The separation process from precipitation to extraction had increased the purity and the highest efficiency recovery of Y was in the extraction process and obtained Y2O3 purer compared to the feed with the Y2O3 content of 92.87%.

Hyperpolarized 89Y NMR spectroscopic detection of yttrium ion and DOTA macrocyclic ligand complexation: pH dependence and Y-DOTA intermediates

Science.gov (United States)

Ferguson, Sarah; Kiswandhi, Andhika; Niedbalski, Peter; Parish, Christopher; Kovacs, Zoltan; Lumata, Lloyd

Dissolution dynamic nuclear polarization (DNP) is a rapidly emerging physics technique used to enhance the signal strength in nuclear magnetic resonance (NMR) and imaging (MRI) experiments for nuclear spins such as yttrium-89 by >10,000-fold. One of the most common and stable MRI contrast agents used in the clinic is Gd-DOTA. In this work, we have investigated the binding of the yttrium and DOTA ligand as a model for complexation of Gd ion and DOTA ligand. The macrocyclic ligand DOTA is special because its complexation with lanthanide ions such as Gd3+ or Y3+ is highly pH dependent. Using this physics technology, we have tracked the complexation kinetics of hyperpolarized Y-triflate and DOTA ligand in real-time and detected the Y-DOTA intermediates. Different kinds of buffers were used (lactate, acetate, citrate, oxalate) and the pseudo-first order complexation kinetic calculations will be discussed. The authors would like to acknowledge the support by US Dept of Defense Award No. W81XWH-14-1-0048 and Robert A. Welch Foundation Grant No. AT-1877.

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

Science.gov (United States)

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.

On the origin of the ultraviolet photoluminescence in the Ce.sup.3+./sup.-doped epitaxial films of multicomponent (Lu,Gd).sub.3./sub.(Ga,Al).sub.5./sub.O.sub.12./sub. garnets

Czech Academy of Sciences Publication Activity Database

Babin, Vladimir; Chernenko, K.; Hanus, M.; Krasnikov, A.; Kučera, M.; Nikl, Martin; Zazubovich, S.

2017-01-01

Roč. 254, č. 4 (2017), 1-6, č. článku 1600570. ISSN 0370-1972 R&D Projects: GA ČR GA16-15569S Institutional support: RVO:68378271 Keywords : antisite Ce 3+ centers * fast ultraviolet photoluminescence * (Lu,Gd) sub >3 sub >(Ga,Al) sub >5 sub >O sub >12 sub > garnets Sub ject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.674, year: 2016

Determination of rare-earth elements, yttrium and scandium in manganese nodules by inductively-coupled argon-plastma emission spectrometry

Science.gov (United States)

Fries, T.; Lamothe, P.J.; Pesek, J.J.

1984-01-01

A sequential-scanning, inductively-coupled argon plasma emission spectrometer is used for the determination of the rare-earth elements, plus yttrium and scandium, in manganese nodules. Wavelength selection is optimized to minimize spectral interferences from manganese nodule components. Samples are decomposed with mixed acids in a sealed polycarbonate vessel, and elements are quantified without further treatment. Results for U.S. Geological Survey manganese nodule standards A-1 and P-1 had average relative standard deviations of 6.8% and 8.1%, respectively, and results were in good agreement with those obtained by other methods. ?? 1984.

Combustion synthesis and photoluminescence in novel red emitting yttrium gadolinium pyrosilicate nanocrystalline phosphor

Energy Technology Data Exchange (ETDEWEB)

Hedaoo, V.P., E-mail: vraikwar@rediffmail.com [Department of Physics, R. J. College, Ghatkopar, Mumbai, MS 400086 (India); Bhatkar, V.B. [Department of Physics, Shri Shivaji Science College, Amravati, MS 444602 (India); Omanwar, S.K. [Department of Physics, SGB Amravati University, Amravati, MS 444602 (India)

2016-07-05

Yttrium Gadolinium Pyrosilicate Y{sub 2-x}Gd{sub x}Si{sub 2}O{sub 7}:Eu{sup 3+} (x = 0.05, 0.10, 0.15) phosphor powder was prepared by facile and time efficient modified combustion method for the first time. The phosphor was characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), photoluminescence excitation (PLE) and emission (PL) spectroscopy and color chromaticity coordinates. XRD revealed the monoclinic crystal structure with space group P1¯. The crystallite size was calculated by Williamson-Hall (W–H) analysis. Nanoplates-like morphology was observed in FESEM analysis with size in the range 50–80 nm. TEM images confirmed the particle size and shape. Upon excitation by 254 nm UV light, the phosphor showed the characteristic red emission peaks at 589 nm and 613 nm corresponding to {sup 5}D{sub 0} → {sup 7}F{sub 1} and {sup 5}D{sub 0} → {sup 7}F{sub 2} transitions respectively. It was observed that the nanocrystalline phosphor Y{sub 2-x}Gd{sub x}Si{sub 2}O{sub 7}:Eu{sup 3+}can be tuned to emit orange to red color by adjusting the ratio Y/Gd. This phosphor thus can be a potential candidate as orange to red color emitting tunable nanocrystalline phosphor for optical devices. - Highlights: • A novel Yttrium Gadolinium Pyrosilicate doped with Eu{sup 3+} is reported. • Facile and time efficient modified combustion method is used. • The nanocrystalline structure was shown by X-ray diffraction, W–H analysis. • FESEM and TEM images confirmed the nanocrystalline structure. • The reported phosphor can be tuned from orange to red by varying Y/Gd ratio.

Ion-irradiation-induced phase transformation in rare earth sesquioxides (Dy2O3,Er2O3,Lu2O3)

International Nuclear Information System (INIS)

Tang, M.; Lu, P.; Valdez, J.A.; Sickafus, K.E.

2006-01-01

Polycrystalline pellets of cubic C-type rare earth structure (Ia3) Dy 2 O 3 , Er 2 O 3 , and Lu 2 O 3 were irradiated at cryogenic temperature (120 K) with 300 keV Kr ++ ions to a maximum fluence of 1x10 20 Kr/m 2 . Irradiated specimens were examined using grazing incidence x-ray diffraction and transmission electron microscopy. Ion irradiation leads to different radiation effects in these three materials. First, Dy 2 O 3 begins to transform to a monoclinic B-type rare earth structure (C2/m) at a peak dose of ∼5 displacements per atom (dpa) (corresponding to a fluence of 2x10 19 Kr/m 2 ). This transformation is nearly complete at a peak dose of 25 dpa (a fluence of 1x10 20 Kr/m 2 ). Er 2 O 3 also transforms to the B-type structure, but the transformation starts at a higher irradiation dose of about 15-20 dpa [a fluence of about (6-8)x10 19 Kr/m 2 ]. Lu 2 O 3 was found to maintain the C-type structure even at the highest irradiation dose of 25 dpa (a fluence of 1x10 20 Kr/m 2 ). No C-to-B transformation was observed in Lu 2 O 3 . The irradiation dose dependence of the C-to-B phase transformation observed in Dy 2 O 3 , Er 2 O 3 , and Lu 2 O 3 is closely related to the temperature dependence of the C-to-B phase transformation found in phase diagrams for these three materials

Growth and laser characterization of mixed Nd:Lu xGd 1-xVO 4 laser crystals

Science.gov (United States)

Yu, Haohai; Yu, Yonggui; Zhang, Huaijin; Wang, Zhengping; Wang, Jiyang; Cheng, Xiufeng; Shao, Zongshu; Jiang, Minhua

2006-08-01

A new series Nd:Lu xGd 1-xVO 4 ( x=0.14, 0.32, 0.50, 0.61, 0.70 and 0.80) mixed laser crystals have been successfully grown by the Czochralski method. The X-ray powder diffraction (XRPD) analysis shows that the as-grown mixed crystals possess the ZrSiO 4 structure. The cell parameters are found to decrease with an increase of x. The optical absorption spectra of the mixed crystals have been measured at room temperature, and five strong-absorption bands centered at the wavelengths of 531, 594, 752, 807 and 880 nm have been revealed in all crystals. They are assigned to the different spin- and electric-dipole-allowed transition from the ground state to the 2K 13/2+ 4G 7/2+ 4G 9/2, 4G 5/2+ 2G 7/2, 4F 7/2+ 4S 3/2, 4F 5/2+ 2H 9/2 and 4F 3/2 energy levels, respectively. A continuous-wave (CW) laser output has been achieved with the mixed crystals at 1.06 μm under laser diode pumping. The maximum CW output power of 377.4 mW has been obtained with the pump power of 2 W, and the corresponding optical conversion efficiency is 18.8%.

China's rare-earth industry

Science.gov (United States)

Tse, Pui-Kwan

2011-01-01

Introduction China's dominant position as the producer of over 95 percent of the world output of rare-earth minerals and rapid increases in the consumption of rare earths owing to the emergence of new clean-energy and defense-related technologies, combined with China's decisions to restrict exports of rare earths, have resulted in heightened concerns about the future availability of rare earths. As a result, industrial countries such as Japan, the United States, and countries of the European Union face tighter supplies and higher prices for rare earths. This paper briefly reviews China's rare-earth production, consumption, and reserves and the important policies and regulations regarding the production and trade of rare earths, including recently announced export quotas. The 15 lanthanide elements-lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium (atomic numbers 57-71)-were originally known as the rare earths from their occurrence in oxides mixtures. Recently, some researchers have included two other elements-scandium and yttrium-in their discussion of rare earths. Yttrium (atomic number 39), which lies above lanthanum in transition group III of the periodic table and has a similar 3+ ion with a noble gas core, has both atomic and ionic radii similar in size to those of terbium and dysprosium and is generally found in nature with lanthanides. Scandium (atomic number 21) has a smaller ionic radius than yttrium and the lanthanides, and its chemical behavior is intermediate between that of aluminum and the lanthanides. It is found in nature with the lanthanides and yttrium. Rare earths are used widely in high-technology and clean-energy products because they impart special properties of magnetism, luminescence, and strength. Rare earths are also used in weapon systems to obtain the same properties.

Structure and properties of intermetallic ternary rare earth compounds

International Nuclear Information System (INIS)

Casper, Frederick

2008-01-01

The so called material science is an always growing field in modern research. For the development of new materials not only the experimental characterization but also theoretical calculation of the electronic structure plays an important role. A class of compounds that has attracted a great deal of attention in recent years is known as REME compounds. These compounds are often referred to with RE designating rare earth, actinide or an element from group 1-4, M representing a late transition metal from groups 8-12, and E belonging to groups 13-15. There are more than 2000 compounds with 1:1:1 stoichiometry belonging to this class of compounds and they offer a broad variety of different structure types. Although many REME compounds are know to exist, mainly only structure and magnetism has been determined for these compounds. In particular, in the field of electronic and transport properties relatively few efforts have been made. The main focus in this study is on compounds crystallizing in MgAgAs and LiGaGe structure. Both structures can only be found among 18 valence electron compounds. The f electrons are localized and therefor not count as valence electrons. A special focus here was also on the magnetoresistance effects and spintronic properties found among the REME compounds. An examination of the following compounds was made: GdAuE (E=In,Cd,Mg), GdPdSb, GdNiSb, REAuSn (RE=Gd,Er,Tm) and RENiBi (RE=Pr,Sm,Gd-Tm,Lu). The experimental results were compared with theoretic band structure calculations. The first half metallic ferromagnet with LiGaGe structure (GdPdSb) was found. All semiconducting REME compounds with MgAgAs structure show giant magnetoresistance (GMR) at low temperatures. The GMR is related to a metal-insulator transition, and the value of the GMR depends on the value of the spin-orbit coupling. Inhomogeneous DyNiBi samples show a small positive MR at low temperature that depends on the amount of metallic impurities. At higher fields the samples show a

Structure and properties of intermetallic ternary rare earth compounds

Energy Technology Data Exchange (ETDEWEB)

Casper, Frederick

2008-12-17

The so called material science is an always growing field in modern research. For the development of new materials not only the experimental characterization but also theoretical calculation of the electronic structure plays an important role. A class of compounds that has attracted a great deal of attention in recent years is known as REME compounds. These compounds are often referred to with RE designating rare earth, actinide or an element from group 1-4, M representing a late transition metal from groups 8-12, and E belonging to groups 13-15. There are more than 2000 compounds with 1:1:1 stoichiometry belonging to this class of compounds and they offer a broad variety of different structure types. Although many REME compounds are know to exist, mainly only structure and magnetism has been determined for these compounds. In particular, in the field of electronic and transport properties relatively few efforts have been made. The main focus in this study is on compounds crystallizing in MgAgAs and LiGaGe structure. Both structures can only be found among 18 valence electron compounds. The f electrons are localized and therefor not count as valence electrons. A special focus here was also on the magnetoresistance effects and spintronic properties found among the REME compounds. An examination of the following compounds was made: GdAuE (E=In,Cd,Mg), GdPdSb, GdNiSb, REAuSn (RE=Gd,Er,Tm) and RENiBi (RE=Pr,Sm,Gd-Tm,Lu). The experimental results were compared with theoretic band structure calculations. The first half metallic ferromagnet with LiGaGe structure (GdPdSb) was found. All semiconducting REME compounds with MgAgAs structure show giant magnetoresistance (GMR) at low temperatures. The GMR is related to a metal-insulator transition, and the value of the GMR depends on the value of the spin-orbit coupling. Inhomogeneous DyNiBi samples show a small positive MR at low temperature that depends on the amount of metallic impurities. At higher fields the samples show a

Size-dependent cytotoxicity of yttrium oxide nanoparticles on primary osteoblasts in vitro

Energy Technology Data Exchange (ETDEWEB)

Zhou, Guoqiang, E-mail: zhougq1982@163.com; Li, Yunfei; Ma, Yanyan; Liu, Zhu; Cao, Lili; Wang, Da; Liu, Sudan; Xu, Wenshi; Wang, Wenying [Hebei University, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of Ministry of Education, Key Laboratory of Chemical Biology of Hebei Province, College of Chemistry and Environmental Science (China)

2016-05-15

Yttrium oxide nanoparticles are an excellent host material for the rare earth metals and have high luminescence efficiency providing a potential application in photodynamic therapy and biological imaging. In this study, the effects of yttrium oxide nanoparticles with four different sizes were investigated using primary osteoblasts in vitro. The results demonstrated that the cytotoxicity generated by yttrium oxide nanoparticles depended on the particle size, and smaller particles possessed higher toxicological effects. For the purpose to elucidate the relationship between reactive oxygen species generation and cell damage, cytomembrane integrity, intracellular reactive oxygen species level, mitochondrial membrane potential, cell apoptosis rate, and activity of caspase-3 in cells were then measured. Increased reactive oxygen species level was also observed in a size-dependent way. Thus, our data demonstrated that exposure to yttrium oxide nanoparticles resulted in a size-dependent cytotoxicity in cultured primary osteoblasts, and reactive oxygen species generation should be one possible damage pathway for the toxicological effects produced by yttrium oxide particles. The results may provide useful information for more rational applications of yttrium oxide nanoparticles in the future.

Gadolinium substitution for yttrium and chemical preparation effects in YBa{sub 2}Cu{sub 3}O{sub 7}: an EPR study; Effets de la substitution de l`yttrium par le gadolinium et de la preparation chimique dans YBa{sub 2}Cu{sub 3}O{sub 7}: etude par RPE

Energy Technology Data Exchange (ETDEWEB)

Bejjit, L.; Haddad, M. [Faculte des Sciences, Meknes (Morocco); Bejjit, L. [Faculte des Sciences, Errachidia (Morocco); Deville, A.; Gaillard, B.; Noel, H. [Universite de Provence, 13 - Marseille (France); Monnereau, O. [Universite de Rennes, 35 - Rennes (France)

1998-01-01

Compounds with yttrium totally or partially substituted by gadolinium in High-T{sub c} superconductor YBa{sub 2}Cu{sub 3}O{sub 7} were prepared. The superconductivity is not affected by this substitution. An orthorhombic structure has been observed in GdBa{sub 2}Cu{sub 3}O{sub 7} sintered and single crystals. The EPR measurements show linewidth dependence on chemical preparation in GdBa{sub 2}Cu{sub 3}O{sub 7}. In Gd-low concentration compounds (x{<=}0.02), a narrow parasite signal, due to the Y{sub 2}BaCuO{sub 5} green phase, appears superimposed to the principal Gd{sup 3+} ions Electron Spin Resonance (EPR) line. (authors) 12 refs.

Unusual magnetic properties of rare-earth titanium oxides RTiO3: effect of the rare earth on the magnetic moment of titanium in Lasub(x)Ysub(1-x)Ti03 and GdTi03

International Nuclear Information System (INIS)

Greedan, J.E.; MacLean, D.A.

1978-01-01

The rare-earth orthotitanites, RTi0 3 are a relatively new series of materials with properties which are strongly dependent on the identity of the rare-earth ion. Low-temperature magnetization studies on the system Lasub(x)Ysub(1-x)Ti0 3 and the compound GdTi0 3 indicate that the magnitude of the Ti 3+ spontaneous moment depends on the average size of the rare-earth ion and on its magnetic moment. For most of the phases studied except GdTi0 3 the Ti 3+ moment is very much smaller than the 'spin only' value and is non-integral, yet semiconducting behaviour is simultaneously observed. (author)

Controls on the composition and extraction of rare earth elements and yttrium (REY) in deep sea polymetallic nodules and sediments

OpenAIRE

Menendez Gamella, Amaya

2017-01-01

Rising demand for metals is driving a search for new mineral resources and mining of seafloor deposits is likely to commence in the next few years. These include polymetallic nodules and crusts that are highly enriched in Mn, Co, Ni, Cu, Mo, Li and Te, and deep-sea clays that can contain high concentrations of the rare earth elements and yttrium (REY). The potential environmental impacts of mining these deposits are, however, poorly constrained and a better understanding of the processes that...

The low-energy β(-) and electron emitter (161)Tb as an alternative to (177)Lu for targeted radionuclide therapy.

Science.gov (United States)

Lehenberger, Silvia; Barkhausen, Christoph; Cohrs, Susan; Fischer, Eliane; Grünberg, Jürgen; Hohn, Alexander; Köster, Ulli; Schibli, Roger; Türler, Andreas; Zhernosekov, Konstantin

2011-08-01

The low-energy β(-) emitter (161)Tb is very similar to (177)Lu with respect to half-life, beta energy and chemical properties. However, (161)Tb also emits a significant amount of conversion and Auger electrons. Greater therapeutic effect can therefore be expected in comparison to (177)Lu. It also emits low-energy photons that are useful for gamma camera imaging. The (160)Gd(n,γ)(161)Gd→(161)Tb production route was used to produce (161)Tb by neutron irradiation of massive (160)Gd targets (up to 40 mg) in nuclear reactors. A semiautomated procedure based on cation exchange chromatography was developed and applied to isolate no carrier added (n.c.a.) (161)Tb from the bulk of the (160)Gd target and from its stable decay product (161)Dy. (161)Tb was used for radiolabeling DOTA-Tyr3-octreotate; the radiolabeling profile was compared to the commercially available n.c.a. (177)Lu. A (161)Tb Derenzo phantom was imaged using a small-animal single-photon emission computed tomography camera. Up to 15 GBq of (161)Tb was produced by long-term irradiation of Gd targets. Using a cation exchange resin, we obtained 80%-90% of the available (161)Tb with high specific activity, radionuclide and chemical purity and in quantities sufficient for therapeutic applications. The (161)Tb obtained was of the quality required to prepare (161)Tb-DOTA-Tyr3-octreotate. We were able to produce (161)Tb in n.c.a. form by irradiating highly enriched (160)Gd targets; it can be obtained in the quantity and quality required for the preparation of (161)Tb-labeled therapeutic agents. Copyright © 2011 Elsevier Inc. All rights reserved.

Preparation of polycrystalline lithium-yttrium fluoride for subsequent mono crystallization

International Nuclear Information System (INIS)

Kowalczyk, E.; Radomski, J.; Diduszko, R.; Iwanejko, J.; Kowalczyk, Z.; Grasza, K.

1994-01-01

High purity lithium-yttrium (YLF) doped with rare earth elements (Nd, Pr, Ho or Tm) was obtained in a two-stage synthesis consisting of (1) reaction of ammonium fluoride with a mixture of lithium carbonate, yttrium oxide, and oxides of lanthanides, and (2) heating of the obtained reaction products at a temperature of about 700 C in an inert gas atmosphere. The phase and chemical purities of the obtained materials were characterized by X-ray diffraction and mass spectrometry techniques. Single crystal growth tests were carried out by means of the Bridgman method. The results showed that the proposed method for manufacture of polycrystalline YLF doped with rare earth elements is appropriate in principle but some parameters of the preparation process are to be more strictly defined. (author). 9 refs, 4 figs, 1 tab

Preparation of polycrystalline lithium-yttrium fluoride for subsequent mono crystallization

Energy Technology Data Exchange (ETDEWEB)

Kowalczyk, E.; Radomski, J.; Diduszko, R.; Iwanejko, J. [Institute of Vacuum Technology, Warsaw (Poland); Kowalczyk, Z. [Warsaw Univ. (Poland); Grasza, K. [Polska Akademia Nauk, Warsaw (Poland). Inst. Fizyki

1994-12-31

High purity lithium-yttrium (YLF) doped with rare earth elements (Nd, Pr, Ho or Tm) was obtained in a two-stage synthesis consisting of (1) reaction of ammonium fluoride with a mixture of lithium carbonate, yttrium oxide, and oxides of lanthanides, and (2) heating of the obtained reaction products at a temperature of about 700 C in an inert gas atmosphere. The phase and chemical purities of the obtained materials were characterized by X-ray diffraction and mass spectrometry techniques. Single crystal growth tests were carried out by means of the Bridgman method. The results showed that the proposed method for manufacture of polycrystalline YLF doped with rare earth elements is appropriate in principle but some parameters of the preparation process are to be more strictly defined. (author). 9 refs, 4 figs, 1 tab.

Rare Earth Chalcogels NaLnSnS4 (Ln = Y, Gd, Tb) for Selective Adsorption of Volatile Hydrocarbons and Gases

KAUST Repository

Edhaim, Fatimah

2017-06-28

The synthesis and characterization of the rare earth chalcogenide aerogels NaYSnS4, NaGdSnS4, and NaTbSnS4 is reported. Rare earth metal ions like Y3+, Gd3+, and Tb3+ react with the chalcogenide clusters [SnS4]4– in aqueous formamide solution forming extended polymeric networks by gelation. Aerogels obtained after supercritical drying have BET surface areas of 649 m2·g–1 (NaYSnS4), 479 m2·g–1 (NaGdSnS4), and 354 m2·g–1 (NaTbSnS4). Electron microscopy and physisorption studies reveal that the new materials have pores in the macro (above 50 nm) and meso (2–50 nm) regions. These aerogels show higher adsorption of toluene vapor over cyclohexane vapor and CO2 over CH4 or H2. The notable adsorption capacity for toluene (NaYSnS4: 1108 mg·g–1; NaGdSnS4: 921 mg·g–1; and NaTbSnS4: 645 mg·g–1) and high selectivity for gases (CO2/H2: 172 and CO2/CH4: 50 for NaYSnS4, CO2/H2: 155 and CO2/CH4: 37 for NaGdSnS4, and CO2/H2: 75 and CO2/CH4: 28 for NaTbSnS4) indicate potential future use of chalcogels in adsorption-based gas or hydrocarbon separation processes.

Production of yttrium

International Nuclear Information System (INIS)

Day, J.G.

1980-01-01

A process is described for the production of yttrium metal, or of an alloy comprising a major proportion of yttrium, in which calcium (metal) and yttrium fluoride are reacted together by use of a submerged electric arc in a molten slag. (author)

Multiple rare-earth ion environments in amorphous (Gd2O3)0.230(P2O5)0.770 revealed by gadolinium K-edge anomalous X-ray scattering

Energy Technology Data Exchange (ETDEWEB)

Cole, Jacqueline M.; Cramer, Alisha J.; Shastri, Sarvjit D.; Mukaddem, Karim T.; Newport, Robert J

2018-04-26

A Gd K-edge anomalous X-ray scattering (AXS) study is performed on the rare-earth (R) phosphate glass, (Gd2O3)0.230(P2O5)0.770, in order to determine Gd…Gd separations in its local structure. The minimum rare-earth separation is of particular interest given that the optical properties of these glasses can quench when rare-earth ions become too close to each other. To this end, a weak Gd…Gd pairwise correlation is located at 4.2(1) Å which is representative of a meta-phosphate R…R separation. More intense first neighbor Gd…Gd pairwise correlations are found at the larger radial distributions, 4.8(1) Å, 5.1(1) Å and 5.4(1) Å. These reflect a mixed ultra-phosphate and meta-phosphate structural character, respectively. A second neighbor Gd…Gd pairwise correlation lies at 6.6(1) Å which is indicative of meta-phosphate structures. Meta- and ultra-phosphate classifications are made by comparing the R…R separations against those of rare-earth phosphate crystal structures, R(PO3)3 and RP5O14 respectively, or difference pair distribution function (PDF) features determined on similar glasses using difference neutron scattering methods. The local structure of this glass is therefore found to display multiple rare-earth ion environments, presumably because its composition lies between these two stoichiometric formulae. These Gd…Gd separations are well resolved in the PDFs that represent the AXS signal. Indeed, the spatial resolution is so good that it also enables the identification of R…X (X = R, P, O) pairwise correlations up to r ~ 9 Å; their average separations lie at r ~ 7.1(1) Å, 7.6(1) Å 7.9(1) Å, 8.4(1) Å and 8.7(1) Å. This is the first report of a Gd K-edge AXS study on an amorphous material. Its demonstrated ability to characterize the local structure of a glass up to such a long-range of r, heralds exciting prospects for AXS studies on other ternary non-crystalline materials. However, the technical challenge of such an experiment

Rare earth impurities in high purity lanthanum oxide determined by neutron activation analysis

International Nuclear Information System (INIS)

Nguyen Van Suc; Desai, H.B.; Parthasarathy, R.; Gangadharan, S.

1992-01-01

Individual rare earth impurities in high purity La 2 O 3 (≥99.9%) have been determined by NAA after pre-separation of the matrix (La). The separation is carried out on an anion exchanger (Dowex 1x8) using different mixtures of methanol/nitric acid as eluants. The rare earth elements from Dy to Lu are eluted quantitatively using a 10% 1M HNO 3 - 90% methanol mixture, while the light rare earths from Ce to Gd are eluted quantitatively using a 10% 0.05M HNO 3 - 90% methanol mixture. La, which is retained on the column, is eluted using 0.1M HNO 3 . The recoveries of the various rare earth elements have been checked using radiotracers and also by spiking the sample with known amount of elements, and the recoveries are found to be quantitative. Results obtained on a typical high purity lanthanum oxide are reported here. (author) 5 refs.; 1 fig

Magnetic Susceptibility of liquid Gd-NM (NM = Cu, Ga, Ge alloys

Directory of Open Access Journals (Sweden)

Shimakura Hironori

2017-01-01

Full Text Available For rare earth alloys, the indirect interaction of RKKY is at work between rare-earth atoms. Therefore, the magnetism of them depends on the number of conduction electrons and the distance between rare-earth metals. In this work, to reveal the relationship between the number of conduction electrons and magnetic property of rare earth metal alloys, magnetic susceptibility measurements for liquid Gd-NM (NM = Cu, Ga, Ge was performed by Faraday method. As the results, it was observed that the sign of paramagnetic Curie temperature of Cu-Gd alloys are positive at all composition, while Ga-Gd and Ge-Gd alloys show negative paramagnetic Curie temperature at certain composition. Moreover, it was indicated when the alloy at certain composition shows highest melting temperature, it has the lowest paramagnetic Curie temperature.

Rare earth elements in the Pacific and Atlantic Oceans

International Nuclear Information System (INIS)

Baar, H.J.W. de; Bacon, M.P.; Brewer, P.G.; Bruland, K.W.

1985-01-01

The first profiles of Pr, Tb, Ho, Tm and Lu in the Pacific Ocean, as well as profiles of La, Ce, Nd, Sm, Eu, Gd and Yb are reported. Concentrations of REE (except Ce) in the deep water are two to three times higher than those observed in the deep Atlantic Ocean. Surface water concentrations are typically lower than in the Atlantic Ocean, especially for the heavier elements Ho,Tm,Yb and Lu. Cerium is strongly depleted in the Pacific water column, but less so in the oxygen minimum zone. The distribution of the REE group is consistent with two simultaneous processes: (1) cycling similar to that of opal and calcium carbonate, and (2) adsorptive scavenging by settling particles and possibly by uptake at ocean boundaries. However, the first process can probably not be sustained by the low REE contents of shells, unless additional adsorption on surfaces is invoked. The second process, adsorptive scavenging, largely controls the oceanic distribution and typical seawater pattern of the rare earths. (author)

Ternary rare-earth based alternative gate-dielectrics for future integration in MOSFETs

Energy Technology Data Exchange (ETDEWEB)

Schubert, Juergen; Lopes, Joao Marcelo; Durgun Oezben, Eylem; Luptak, Roman; Lenk, Steffi; Zander, Willi; Roeckerath, Martin [IBN 1-IT, Forschungszentrum Juelich, 52425 Juelich (Germany)

2009-07-01

The dielectric SiO{sub 2} has been the key to the tremendous improvements in Si-based metal-oxide-semiconductor (MOS) device performance over the past four decades. It has, however, reached its limit in terms of scaling since it exhibits a leakage current density higher than 1 A/cm{sup 2} and does not retain its intrinsic physical properties at thicknesses below 1.5 nm. In order to overcome these problems and keep Moore's law ongoing, the use of higher dielectric constant (k) gate oxides has been suggested. These high-k materials must satisfy numerous requirements such as the high k, low leakage currents, suitable band gap und offsets to silicon. Rare-earth based dielectrics are promising materials which fulfill these needs. We will review the properties of REScO{sub 3} (RE = La, Dy, Gd, Sm, Tb) and LaLuO{sub 3} thin films, grown with pulsed laser deposition, e-gun evaporation or molecular beam deposition, integrated in capacitors and transistors. A k > 20 for the REScO{sub 3} (RE = Dy, Gd) and around 30 for (RE = La, Sm, Tb) and LaLuO{sub 3} are obtained. Transistors prepared on SOI and sSOI show mobility values up to 380 cm{sup 2}/Vs on sSOI, which are comparable to such prepared with HfO{sub 2}.

Measurement of Gd content in (U,Gd)O2 using thermal gravimetric analysis

International Nuclear Information System (INIS)

Kim, Keon Sik; Yang, Jae Ho; Kang, Ki Won; Song, Kun Woo; Kim, Gil Moo

2004-01-01

We propose a simple and precise method for measuring the Gd content in the (U,Gd)O 2 pellet by only measuring the weight variation of the pellet during thermal heat treatment in air. The (U,Gd)O 2 fuel pellets were oxidized at 475 deg. C, subsequently heat treated at 1300 deg. C, and then cooled to room temperature in air. The accompanying weight variations were measured using thermo gravimetric analysis (TGA). The measured weight variations were mathematically analyzed with reference to the successive phase reactions during the heat treatment. This method provides an advantage in that the rare-earth element content including Gd can be measured using relatively simple equipment such as an electric furnace and a balance

Spectrographic determination of some rare earths in thorium compounds

International Nuclear Information System (INIS)

Brito, J. de.

1977-01-01

A method for spectrographic determination of Gd, Sm, Dy, Eu, Y, Yb, Tm and Lu in thorium compounds has been developed. Sensibilities of 0.01 μg rare earths/g Th02 were achieved. The rare earth elements were chromatographycally separated in a nitric acid-ether-cellulose system. The solvent mixture was prepared by dissolving 11% of concentrated nitric acid in ether. The method is based upon the sorption of the rare earths on activated cellulose, the elements being eluted together with 0.01 M HNO 3 . The retention of the 152 , 154 Eu used as tracer was 99,4%. The other elements showed recoveries varying from 95 to 99%. A direct carrier destillation procedure for the spectrochemical determination of the mentioned elements was used. Several concentrations of silver chloride were used to study the volatility behavior of the rare earths. 2%AgCl was added to the matrix as definite carrier, being lantanum selected as internal standard. The average coefficient of variation for this method was +- -+ 7%. The method has been appleid to the analysis of rare earths in thorium coumpounds prepared by Thorium Purification Pilot Plant at Atomic Energy Institute, Sao Paulo [pt

The Application of CPA to Calculations of the Mean Magnetic Moment in the Gd1-xNi, Gd1-xFe, Gd1xCox, and Y1-xCox Intermetallic Compounds

DEFF Research Database (Denmark)

Szpunar, B.; Kozarzewski, B.

1977-01-01

with a narrow d-band is considered. The magnetic moment of the alloy at zero temperature is calculated within the molecular field and Hartree-Fock approximations. Disorder is treated in the coherent potential approximation. Results are in good agreement with the experimental data obtained for the crystalline......Calculations are made of the mean magnetic moment per atom of the transition metal and the rare-earth metal in the intermetallic compounds, Gd1-x,Nix, Gd1-x Fex, Gd1-x Cox, and Y1-x Cox. A simple model of the disordered alloy consisting of spins localized on the rare-earth atoms and interacting...

Ln3+ (Ln=Ce, Tb, Dy) and Hf doping of LuI3 powders – A material and spectroscopic study

International Nuclear Information System (INIS)

Wiatrowska, Aneta; Keur, Wilco; Ronda, Cees

2016-01-01

The moisture sensitivity of LuI 3 :Ce,Hf and luminescent properties of undoped LuI 3 and LuI 3 :M (M=Ce 3+ , Tb 3+ , Dy 3+ ) powders were investigated. The possibility of improving the air and moisture stability of LuI 3 :Ce by Hf doping was tested. It was proven that the Hf contribution to the LuI 3 :Ce stability is very limited and is insignificant to render LuI 3 :Ce scintillator powders suitable for applications. Photoluminescence results of LuI 3 without dopants added on purpose showed luminescence due to a plurality of rare-earth elements' impurities. Two types of self-trapped luminescence were found. Energy transfer between host lattice, self-trapped excitons and rare-earth ions was investigated.

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

Science.gov (United States)

Glasbrenner, James; Belashchenko, Kirill

2010-03-01

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

Water-stable NaLuF4-based upconversion nanophosphors with long-term validity for multimodal lymphatic imaging.

Science.gov (United States)

Zhou, Jing; Zhu, Xingjun; Chen, Min; Sun, Yun; Li, Fuyou

2012-09-01

Multimodal imaging is rapidly becoming an important tool for biomedical applications because it can compensate for the deficiencies of individual imaging modalities. Herein, multifunctional NaLuF(4)-based upconversion nanoparticles (Lu-UCNPs) were synthesized though a facile one-step microemulsion method under ambient condition. The doping of lanthanide ions (Gd(3+), Yb(3+) and Er(3+)/Tm(3+)) endows the Lu-UCNPs with high T(1)-enhancement, bright upconversion luminescence (UCL) emissions, and excellent X-ray absorption coefficient. Moreover, the as-prepared Lu-UCNPs are stable in water for more than six months, due to the protection of sodium glutamate and diethylene triamine pentacetate acid (DTPA) coordinating ligands on the surface. Lu-UCNPs have been successfully applied to the trimodal CT/MR/UCL lymphatic imaging on the modal of small animals. It is worth noting that Lu-UCNPs could be used for imaging even after preserving for over six months. In vitro transmission electron microscope (TEM), methyl thiazolyl tetrazolium (MTT) assay and histological analysis demonstrated that Lu-UCNPs exhibited low toxicity on living systems. Therefore, Lu-UCNPs could be multimodal agents for CT/MR/UCL imaging, and the concept can be served as a platform technology for the next-generation of probes for multimodal imaging. Copyright © 2012 Elsevier Ltd. All rights reserved.

Yttrium aluminum garnet (YAG) obtained by rare-earth mixed oxide (RE2O3)

International Nuclear Information System (INIS)

Castro, D.F.; Daguano, J.K.M.F.; Rodrigues Junior, D.; Suzuki, P.A.; Silva, O.M.M.

2010-01-01

In this work, the substitution of commercial Y 2 O 3 by a rare earth mixed oxide, RE 2 O 3 , to form Yttrium aluminum Garnet-Y 3 Al 5 O 12 , was investigated. Al 2 O 3 :Y 2 O 3 and Al 2 O 3 :RE 2 O 3 powder-mixtures, in a molar ratio of 60:40, were milled and subsequently cold uniaxially-pressed. Compacts were sintered at 1000, 1400 or 1600 deg C, for 120 minutes. RE 2 O 3 oxide was characterized by high-resolution synchrotron X-ray diffraction (HRXRD) and compared to Y 2 O 3 . X-ray diffraction pattern of the RE 2 O 3 indicates a true solid solution formation. Rietveld refinement of the sintered YAG and (RE)AG reveled a similar crystal structure to the YAGs obtained by the use of Al 2 O 3 -Y 2 O 3 or Al 2 O 3 -RE 2 O 3 respectively. Microstructural analysis of both, YAG or (RE)AG, revealed similar grain sizes of about 2.5 μm besides mechanical properties, with hardness of 400HV and fracture toughness of 3.8MPa.m1/2. It could be, thus, demonstrated that pure Y 2 O 3 can be substituted by the rare-earth solid solution, RE 2 O 3 , in the formation YAGs, presenting similar microstructural and mechanical properties. (author)

Evaluation of the 175Lu(n,2n)174Lu, 175Lu(n,2n/sup 174m/Lu, and 175Lu(n,3n)173Lu cross sections from threshold to 20 MeV

International Nuclear Information System (INIS)

Philis, C.; Young, P.G.; Arthur, E.D.

1978-04-01

An evaluation of the 175 Lu(n,2n) 174 Lu, 175 Lu(n,2n)/sup 174m/Lu, and 175 Lu(n,3n) 173 Lu reactions from threshold to 20 MeV is presented. Available experimental data were renormalized to a consistent set of standards and were used along with results from statistical-preequilibrium model calculations to produce recommended curves for each of these reactions

Separation and purification of gadolinium and others rare earths, and yttrium

International Nuclear Information System (INIS)

Awwal, M.A.; Filgueiras, S.A.C.

1988-01-01

The experimental works in laboratories for developing a solvent extraction process with the purpose of gadolinium separation and purification, and secondarily samarium, europium, lanthanum and yttrium are described. Using as solvent di-2-ethylhexylphosphoric acid (DEHPA) a preliminary flow chart for separation for these elements are developed. (author)

Experimental half-life determination of 176Lu

International Nuclear Information System (INIS)

Kossert, Karsten; Jörg, Gerhard; Gostomski, Christoph Lierse v.

2013-01-01

The half-life of the naturally occurring long-lived rare earth isotope 176 Lu was determined by a combination of highly sophisticated experimental procedures in order to further improve the reliability and the precision of literature data. The amount of lutetium in the samples was determined by inductively coupled plasma optical emission spectrometry (ICP-OES) using a NIST reference standard. The isotopic ratio N( 176 Lu)/N(Lu) in the samples was measured by means of inductively coupled plasma high resolution mass spectrometry (ICP-HRMS). The activity divided by the mass of Lu was determined by applying liquid scintillation (LS) counting. The LS counting efficiency of the beta/gamma emitter 176 Lu was determined with the CIEMAT/NIST efficiency tracing technique with low uncertainty. The influences of colour quenching and background effects are discussed in this paper. The half-life was found to be 3.640(35)×10 10 y. The result is in good agreement with other evaluations and the relative standard uncertainty of 0.95% is among the lowest of previously published data. - Highlights: • The half-life of 176 Lu was determined by ICP-OES, ICP-HRMS and LSC. • The LSC efficiency was determined with the CIEMAT/NIST method. • The half-life was found to be 3.640(35)×10 10 y

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

Directory of Open Access Journals (Sweden)

P. Logamani

2017-06-01

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

Assessing rare earth elements in quartz rich geological samples.

Science.gov (United States)

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.

Coprecipitation of yttrium and aluminium hydroxide for preparation of yttrium aluminium garnet

NARCIS (Netherlands)

Vrolijk, J.W.G.A.; Willems, J.W.M.M.; Metselaar, R.

1990-01-01

Coprecipitation of yttrium and aluminium hydroxide for the preparation of pure yttrium aluminium garnet (YAG) powder with small grain size is the subject of this study. Starting materials are sulphates and chlorides of yttrium and aluminium. To obtain pure YAG (Y3Al5O12), the pH during flocculation

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

International Nuclear Information System (INIS)

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

2014-01-01

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

An ICP AES method for determination of dysprosium and terbium in high purity yttrium oxide

International Nuclear Information System (INIS)

Rupawate, V.H.; Hareendran, K.N.; Roy, S.B.

2011-01-01

High purity yttrium finds interesting application in astronavigation, luminescence, nuclear energy and metallurgical industries. Most of these applications require yttrium oxide of highest purity. Consequently there is a need for production of high purity yttrium oxide. Separation and purification of yttrium from other rare earths is a challenging task due to their close chemical properties. Liquid-liquid extraction and ion exchange have been widely used in the production of yttrium oxide of highest purity. Determination of impurities, especially other rare earths, in ppm level is required for process development and chemical characterization of the high purity Y 2 O 3 . Many methods have been described in literature. However since the advent of ICP AES much work in this area has been carried out by this technique. This paper describes the work done for determination of dysprosium (Dy) and terbium (Tb) in yttrium oxide using a high resolution sequential ICP AES. Emission spectra of rare earth elements are very complex and due to this complexity it is important to select spectral interference free analyte lines for determination of rare earths in rare earth matrix. For the determination of Dy and Tb in Y 2 O 3 , sensitive lines of Dy and Tb are selected from the instrument wavelength table and spectral interference free emission lines for the determination is selected by scanning around the selected wavelengths using 5 g/L Y solution and 5 mg/L standard solutions of Dy and Tb prepared in 4% nitric acid. It is found 353.170 nm line of Dy and 350.917 nm line Tb is suitable for quantitative determination. The signal to background ratio increases with increase in matrix concentration, i.e. from 1 to 5 mg/L. The optimum forward power is determined and it is found to be 1100W for Dy and 1000W for Tb. The instrument is calibrated using matrix matched standards containing 5g/L of Y matrix. Samples are dissolved in nitric acid and Y concentration is maintained at 5g/L. Two

Positive effect of yttrium on the reduction of pores in cast Al alloy

International Nuclear Information System (INIS)

Hua, Guomin; Ahmadi, Hojat; Nouri, Meisam; Li, Dongyang

2015-01-01

Mechanical and electrochemical properties of Al alloys can be improved by adding a small amount of rare-earth such as yttrium. Here we demonstrate that adding yttrium also helps suppress the porosity in cast Al alloys, thus minimizing its detrimental effect on mechanical properties of the alloys. The mechanism behind is elucidated based on the hydrogen binding energies and the diffusion activation energies of hydrogen atoms in Al and Al–Y phases, calculated using the first-principle method. - Highlights: • The porosity of commercial Al alloy can be reduced by additive yttrium. • Formed Al 3 Y phase helps reduce homogeneous nucleation of hydrogen bubbles. • Formed Al 3 Y and Al 2 Y phases could suppress the growth of hydrogen bubbles

Investigation of neutron-rich rare-earth nuclei including the new isotopes 177Tm and 184Lu

International Nuclear Information System (INIS)

Rykaczewski, K.; Gippert, K.L.; Runte, E.; Schmidt-Ott, W.D.; Tidemand-Petersson, P.; Kurcewicz, W.; Nazarewicz, W.

1989-01-01

Decays of neutron-rich isotopes in the rare-earth region were studied by means of on-line mass separation and β-γ spectroscopy using multinucleon-transfer reactions between beams of 136 Xe (9 and 11.7 MeV/u), 186 W (11.7 and 15 MeV/u) and 238 U (11.4 MeV/u) and targets of nat W and Ta. The higher beam energies appear to be advantageous for the production of such isotopes. Two new isotopes were identified: 177 Tm with a half-life T 1/2 = 85±10/15 s, and 184 Lu with T 1/2 ≅ 18 s. A new 47 s-activity found at A = 171 is tentatively assigned to the decay of the new isotope 171 Ho. The properties of the ground and excited states of neutron-rich lanthanide isotopes are interpreted within the shell model using the deformed Woods-Saxon potential. A change of the ground-state configuration for odd-mass neutron-rich lutetium isotopes from π 7/2 + [404] to π 9/2 - [514] is suggested, this change being due to the influence of a large hexadecapole deformation. The role of a possible isometric state in 180 Lu for the nucleosynthesis of 180m Ta is discussed. (orig.)

Thermoanalytical, spectroscopic and DFT studies of heavy trivalent lanthanides and yttrium(III) with oxamate as ligand

Energy Technology Data Exchange (ETDEWEB)

Caires, Flavio Junior; Gaglieri, Caroline, E-mail: caires.flavio@fc.unesp.br [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Bauru, SP (Brazil). Faculdade de Ciencias; Nunes, Wilhan Donizete Goncalves; Nascimento, Andre Luiz Carneiro Soares do; Teixeira, Jose Augusto; Zangaro, Georgia Alvim Coelho; Treu-Filho, Oswaldo; Ionashiro, Massao [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Araraquara, SP (Brazil)

2017-07-15

Solid-state LnL{sub 3}∙nH{sub 2}O complexes, where Ln stands for trivalent lanthanides (Tb to Lu) or yttrium(III) and L is oxamate (NH{sub 2}COCO{sub 2}{sup -}), have been synthesized. The characterization of the complexes was performed by using elemental analysis (EA), complexometric titration with EDTA, thermoanalytical techniques such as simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC), evolved gas analysis (TG-FTIR), infrared spectroscopy (IR) and powder X-ray diffraction (XRPD). The results provided information about thermal behavior, crystallinity, stoichiometry, coordination sites, as well as the products released during thermal degradation of the complexes studied. Theoretical calculation of yttrium oxamate, as representative of all complexes was performed using density functional theory (DFT) for studying the molecular structure and vibrational spectrum of the investigated molecule in the ground state. The optimized geometrical parameters and theoretical vibrational spectrum obtained by DFT calculations are in good agreement with the experimental results. (author)

The RELixSn2 (RE=La–Nd, Sm, and Gd; 0≤x<1) series revisited. Synthesis, crystal chemistry, and magnetic susceptibilities

International Nuclear Information System (INIS)

Makongo, Julien P.A.; Suen, Nian-Tzu; Guo, Shengping; Saha, Shanta; Greene, Richard; Paglione, Johnpierre; Bobev, Svilen

2014-01-01

This study is concerned with the ternary compounds RELi x Sn 2 (RE=La–Nd, Sm, and Gd; 0≤x 2 phases. These materials crystallize with the base-centered orthorhombic space group Cmcm (No. 63), and can be formally assigned with the CeNiSi 2 structure type (Pearson symbol oC16). Our systematic single-crystal X-ray diffraction studies revealed substantial Li-deficiencies in all cases, with SmSn 2 (space group Cmmm, ZrGa 2 structure type, Pearson symbol oC12) and GdSn 2 (space group Cmcm, ZrSi 2 structure type, Pearson symbol oC12) being completely lithium-free. The structure refinements also uncovered positional disorder on the Sn site neighboring the vacancies. The Sn-disorder and the Li-deficiency correlate, and vary monotonically with the decreased size of the rare-earth atoms in the order RE=La–Nd. The SmSn 2 and GdSn 2 structures are devoid of any disorder. Temperature-dependent studies of the magnetic response of the title compounds are also presented and discussed. -- Graphical abstract: RELi x Sn 2 (RE=La–Nd, 0≤x 2 structure type (a). The Sn-disorder and the Li-deficiency correlate, and vary monotonically with the decreased size of the rare-earth atoms in the order RE=La–Nd. The SmSn 2 (b) and GdSn 2 (c) structures are devoid of any disorder. Highlights: • The crystal structures of the RELi x Sn 2 (RE=La–Nd, 0≤x 2 structure type or defect variant of the CeNiSi 2 structure type. • SmSn 2 is isotypic with the ZrGa 2 structure, while RESn 2 (RE=Gd–Lu) are isotypic with the ZrSi 2 structure

Unactivated yttrium tantalate phosphor

International Nuclear Information System (INIS)

Reddy, V.B.; Cheung, H.K.

1992-01-01

This patent describes an unactivated yttrium tantalate phosphor having M prime monoclinic structure and containing one or more additives of Rb and Al in an amount of between about 0.001 to 0.1 moles per mole of yttrium tantalate to improve brightness under X-radiation. This patent also describes an unactivated yttrium tantalate phosphor having M prime monoclinic structure and containing additives of Sr in an amount of between 0.001 to 0.1 moles per mole of yttrium tantalate and one or more of Rb and Al in an amount of between 0.001 to 0.1 moles per mole of yttrium tantalate the phosphor exhibiting a greater brightness under X-radiation than the phosphor absent Rb and Al

Optical and scintillation characteristics of Gd.sub.2./sub.YAl.sub.2./sub.Ga.sub.3./sub.O.sub.12./sub.:Ce and Lu.sub.2./sub.YAl.sub.2./sub.Ga.sub.3./sub.O.sub.12./sub.:Ce single crystals

Czech Academy of Sciences Publication Activity Database

Chewpraditkul, W.; Sakthong, O.; Pattanaboonmee, N.; Chewpraditkul, We.; Szczesniak, T.; Swiderski, L.; Moszynski, M.; Kamada, K.; Yoshikawa, A.; Nikl, Martin

2017-01-01

Roč. 468, Jun (2017), 395–398 ISSN 0022-0248 R&D Projects: GA ČR GA16-15569S Institutional support: RVO:68378271 Keywords : Ce-doping * Czochralski method * Gd 2 YAl 2 Ga 3 O 12 :Ce * Lu 2 YAl 2 Ga 3 O 12 :Ce * luminescence * scintillator materials Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.751, year: 2016

Rare earth chalcogels NaLnSnS{sub 4} (Ln = Y, Gd, Tb) for selective adsorption of volatile hydrocarbons and gases

Energy Technology Data Exchange (ETDEWEB)

Edhaim, Fatimah; Rothenberger, Alexander [Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal (Saudi Arabia)

2017-08-16

The synthesis and characterization of the rare earth chalcogenide aerogels NaYSnS{sub 4}, NaGdSnS{sub 4}, and NaTbSnS{sub 4} is reported. Rare earth metal ions like Y{sup 3+}, Gd{sup 3+}, and Tb{sup 3+} react with the chalcogenide clusters [SnS{sub 4}]{sup 4-} in aqueous formamide solution forming extended polymeric networks by gelation. Aerogels obtained after supercritical drying have BET surface areas of 649 m{sup 2}.g{sup -1} (NaYSnS{sub 4}), 479 m{sup 2}.g{sup -1} (NaGdSnS{sub 4}), and 354 m{sup 2}.g{sup -1} (NaTbSnS{sub 4}). Electron microscopy and physisorption studies reveal that the new materials have pores in the macro (above 50 nm) and meso (2-50 nm) regions. These aerogels show higher adsorption of toluene vapor over cyclohexane vapor and CO{sub 2} over CH{sub 4} or H{sub 2}. The notable adsorption capacity for toluene (NaYSnS{sub 4}: 1108 mg.g{sup -1}; NaGdSnS{sub 4}: 921 mg.g{sup -1}; and NaTbSnS4: 645 mg.g{sup -1}) and high selectivity for gases (CO{sub 2}/H{sub 2}: 172 and CO{sub 2}/CH{sub 4}: 50 for NaYSnS{sub 4}, CO{sub 2}/H{sub 2}: 155 and CO{sub 2}/CH{sub 4}: 37 for NaGdSnS{sub 4}, and CO{sub 2}/H{sub 2}: 75 and CO{sub 2}/CH{sub 4}: 28 for NaTbSnS{sub 4}) indicate potential future use of chalcogels in adsorption-based gas or hydrocarbon separation processes. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Determination of rare earth elements in rocks by neutron activation analysis with pre-irradiation separation

International Nuclear Information System (INIS)

Alcala, A.L.

1991-01-01

Rare earth elements were determined by neutron activation analysis in rocks, a group separation before irradiation was developed. The international reference standards AGV-1, BE-N and JB-1, as well the Brazilian geological standards BB-1 and GB-1, provided by the Instituto de Geociencias da Universidade Federal da Bahia, were analysed. The method was based on acid digestion of the samples, cation exchange separation, and coprecipitation of the REE with calcium oxalate. Interferents like U, Th, Ta and Fe were eliminated. The concentration values of eleven REE's (La, Co, Pr, Nd, Sm, Eu, Gd, Tb, Ho, Yb and Lu) were determined. (author)

Kinetic properties of solid yttrium at high temperatures

International Nuclear Information System (INIS)

Ivliev, A.D.

1993-01-01

Analysis of results of experimental investigation into temperature-diffusivity, specific electroresistance and heat conductivity of yttrium is carried out. Peculiarities of variation of its kinetic characteristics under high temperatures are shown to result from two-band character of energy spectrum of collectivized electrons. In particular, growth of heat conductivity results from reduction of density of heavy electron states under heating. The suggested model describes kinetic characteristics of lutetium, as well. Usage of this model for the rest heavy rare-earth metals enables to make conclusion about reduction of magnetic scattering effcieincy in the rare-earth metals in proportion to approximation to melting temperature

Photoluminescence and scintillation properties of Ce-doped Sr2(Gd1-xLux)8(SiO4)6O2 (x = 0.1, 0.2, 0.4, 0.5, 0.6) crystals

Science.gov (United States)

Igashira, Takuya; Kawano, Naoki; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

2018-05-01

Apatite crystals with chemical compositions of 0.5% Ce-doped Sr2(Gd1-xLux)8(SiO4)6O2 (x = 0.1, 0.2, 0.4, 0.5, 0.6) were synthesized by the Floating Zone method, and then we evaluated their photoluminescence (PL) and scintillation properties. All the Ce-doped samples exhibited PL and scintillation with an intense broad emission in 400-550 nm in which the origin was attributed to the 5d-4f transition of Ce3+, and the emission peak became broader with increasing the concentration of Lu3+. Both PL and scintillation decay time profiles were best-approximated by a sum of two exponential decay functions, and the origin of slower component was attributed to the 5d-4f transition of Ce3+. In the X-ray induced afterglow measurements, the Ce-doped Sr2(Gd0.4Lu0.6)8(SiO4)6O2 sample exhibited the lowest afterglow level. Furthermore, the Ce-doped Sr2(Gd0.5Lu0.5)8(SiO4)6O2 and Sr2(Gd0.4Lu0.6)8(SiO4)6O2 samples showed a clear full energy deposited peak under 5.5 MeV 241Am α-ray irradiation, and the estimated absolute scintillation light yields were around 290 and 1300 ph/5.5 MeV-α, respectively.

Pemisahan Unsur Samarium dan Yttrium dari Mineral Tanah Jarang dengan Teknik Membran Cair Berpendukung (Supported Liquid Membrane

Directory of Open Access Journals (Sweden)

Amri Amin

2009-06-01

Full Text Available he increasing use of rare earth elements in high technology industries needs to be supported by developmental work for the separation of elements. The research objective is fiercely attracting and challenging considering the similarity of bath physical and chemical properties among these elements. The rate separation of samarium and yttrium elements using supported liquid membrane has been studied. Polytetrafluoroethylene (PTFE with pore size of 0.45 µm has been used as the membrane and di(2-ethylhexyl phosphate (D2EHP in hexane has been used as a carrier and nitric acid solution has been used as receiving phase. Result of experiments showed that the best separation rate of samarium and yttrium elements could be obtained at feeding phase of pH 3.0, di(2-ethylhexyl phosphate (D2EHP concentration of 0.3 M, agitation rate of 700 rpm, agitation time of 2 hours, and nitric acid and its solution concentrations of 1.0 M and 0.1 M, respectively. At this condition, separation rates of samarium and yttrium were 64.4 and 67.6%, respectively.   Keywords: liquid membrane, rare earth elements, samarium, yttrium

Cross sections of (n, α) reactions on rare-earth elements from Tb through Lu at En ∼ 14 MeV

International Nuclear Information System (INIS)

Kadenko, A.O.; Gorbachenko, O.M.; Primenko, G.I.; Kadenko, I.M.; Plujko, V.A.

2012-01-01

The cross sections of the neutron reactions at E n = 14.6 MeV on the isotopes of Tb-159, Dy-164, Er-168, Er-170, Yb-174, Yb-176, Lu-175, and Lu-176 with alpha-particle emission were studied by the use of new experimental data and different theoretical approaches. New and improved experimental data were obtained with the neutron-activation technique. The samples of natural composition of rare earth elements were irradiated with d-t neutrons from the neutron generator NG-300. Gamma-ray spectra of the induced activities of irradiated samples were measured with HPGe spectrometer. The uncertainties of the experimental cross sections were thoroughly estimated. Available experimental results and evaluated nuclear data from the EXFOR, TENDL, ENDF data libraries were compared with different systematics and calculations with the EMPIRE 3.0 and TALYS 1.2 codes. Contribution of pre-equilibrium decay was analyzed. Different systematics for estimations of the investigated cross-sections have been tested

Extraction of rare earths and hydrochloric acid by trialkylphosphine oxide

International Nuclear Information System (INIS)

Mikhajlichenko, A.I.; Karmannikov, V.P.; Klimenko, M.A.; Fedulova, T.V.

1983-01-01

Extraction of rare earth chlorides and hydrochloric acid by trialkylphosphine oxide with different radicals (POR) (RR' 2 PO-POR, where RR'=alkyl of a normal structure, containing 7 to 9 carbon atoms, R=isoamyl) has been studied. Distribution of lanthanum-, neodymium-, lutetium- and yttrium chlorides during extraction with 1.28 mol/l POR solution in white spirit is investigated in the salt concentration range in the equilibrium aqueous phase from 0 to 2.8 mol/l. Lanthanide distribution coefficients increase with an increase in the order number of elements, with the separation coefficients of two extreme members of the series (Lu and La) for chlorides and nitrates constituting 100 and 80, respectively microquantities of Ln against the background of macroquantities of La is 2.6 mol/l. According to the results of measurements of viscosity, electric conductivity and water content in the extracts a conclusion is made on the state of salt in the organic phase. In the systems POR-LnCl 3 -HCl-H 2 O the hydrochloric acid extraction increases with an increase in the rare earth chloride concentration and order number of the element

Rare earth element patterns in nigerian coals

International Nuclear Information System (INIS)

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

1996-01-01

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

Instrumental neutron activation analysis of rocks from Cayajabos petroleum ore

International Nuclear Information System (INIS)

Montero Cabrera, M.E.; Herrera Hernandez, H.; Herrera Peraza, E.; Rodriguez Martinez, N.; Lopez Reyes, M.C.

2000-01-01

The relative INAA method under statistical control was used to measure the concentrations of Sb, La, Eu, Co, Rb, Tb, Cs, Hf, Th, Cr, Lu, Yb, Ce, Sm, Gd, Nd. Rare earth element (REE) Chondrite-normalized patterns are presented. The La cond /Lu cond normalized concentration ratios obtained confirm the carbonaceous character of the rocks

On the structure of rare earth periodates of LnIO5x4H2O (Ln=Pr-Lu, Y)

International Nuclear Information System (INIS)

Shamraj, N.B.; Varfolomeev, M.B.; Saf'yanov, Yu.N.; Kuz'min, Eh.A.; Ilyukhin, V.V.; AN SSSR, Moscow. Inst. Kristallografii)

1977-01-01

The crystal structure of three representatives of an isotypic series of monoclinic periodates of rare earth elements in the series from Pr to Lu and Y was deciphered. The monoclinic cell for all LnIO 5 x4H 2 O contains Z=4 formula units. The architectural motif consists in layers of octahedra of IO 4 (OH) 2 and polyhedra of LnO 5 (H 2 O 3 ) parallel to the (100) plane. Adhesion between the layers is achieved through H-bonds

A routine high-precision method for Lu-Hf isotope geochemistry and chronology

Science.gov (United States)

Patchett, P.J.; Tatsumoto, M.

1981-01-01

A method for chemical separation of Lu and Hf from rock, meteorite and mineral samples is described, together with a much improved mass spectrometric running technique for Hf. This allows (i) geo- and cosmochronology using the176Lu???176Hf+??- decay scheme, and (ii) geochemical studies of planetary processes in the earth and moon. Chemical yields for the three-stage ion-exchange column procedure average 90% for Hf. Chemical blanks are international mass spectrometric standard; suitable aliquots, prepared from a single batch of JMC 475, are available from Denver. Lu-Hf analyses of the standard rocks BCR-1 and JB-1 are given. The potential of the Lu-Hf method in isotope geochemistry is assessed. ?? 1980 Springer-Verlag.

Double Solvent for Extracting Rare Earth Concentrate

International Nuclear Information System (INIS)

Bintarti, AN; Bambang EHB

2007-01-01

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

Rare (Earth Elements [score

Directory of Open Access Journals (Sweden)

Camilo Méndez

2014-12-01

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

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

Energy Technology Data Exchange (ETDEWEB)

Rajivgandhi, R. [Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 (India); Arout Chelvane, J. [Defence Metallurgical Research Laboratory, Hyderabad 500 058 (India); Quezado, S.; Malik, S.K. [Departamento de F’ısica Teorica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59072-970 (Brazil); Nirmala, R., E-mail: nirmala@physics.iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 (India)

2017-07-01

Highlights: • Melt-spinning yields microcrystalline RNi (R = Gd, Tb and Ho) samples with texture. • The texture-induced anisotropy affects magnetic and magnetocaloric properties. • Melt-spinning helps one engineer magnetocaloric effect in rare-earth compounds. - Abstract: Magnetocaloric effect (MCE) in RNi (where R = Gd, Tb and Ho) compounds has been studied in their arc-melted and melt-spun forms. The compound GdNi has the orthorhombic CrB-type structure (Space group Cmcm, No. 63) and the compound HoNi has the orthorhombic FeB-type structure (Space group Pnma, No. 62) at room temperature regardless of their synthesis condition. However, arc-melted TbNi orders in a monoclinic structure (Space group P2{sub 1}/m, No. 11) and when it is rapidly quenched to a melt-spun form, it crystallizes in an orthorhombic structure (Space group Pnma, No. 62). The arc-melted GdNi, TbNi and HoNi compounds order ferromagnetically at ∼69 K, ∼67 K and ∼36 K (T{sub C}) respectively. While the melt-spun GdNi shows about 6 K increase in T{sub C}, the ordering temperature of TbNi remains nearly the same in both arc-melted and melt-spun forms. In contrast, a reduction in T{sub C} by about 8 K is observed in melt-spun HoNi, when compared to its arc-melted counterpart. Isothermal magnetic entropy change, ∆S{sub m}, calculated from the field dependent magnetization data indicates an enhanced relative cooling power (RCP) for melt-spun GdNi for field changes of 20 kOe and 50 kOe. A lowered RCP value is observed in melt-spun TbNi and HoNi. These changes could have resulted from the competing shape anisotropy and the granular microstructure induced by the melt-spinning process. Tailoring the MCE of rare earth intermetallic compounds by suitably controlled synthesis techniques is certainly one of the directions to go forward in the search of giant magnetocaloric materials.

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

International Nuclear Information System (INIS)

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

2017-01-01

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

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

Science.gov (United States)

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.

Effect of yttrium on the oxide scale adherence of pre-oxidized silicon-containing heat-resistant alloy

International Nuclear Information System (INIS)

Yan Jingbo; Gao Yimin; Shen Yudi; Yang Fang; Yi Dawei; Ye Zhaozhong; Liang Long; Du Yingqian

2011-01-01

Highlights: → AE experiment shows yttrium has a beneficial effect on the pre-oxidized HP40 alloy. → Yttrium facilitates the formation of internal oxide after 10 h of oxidation. → Internal oxide changes the rupture behaviour of the oxide scale. → Twins form in the internal oxide and improve the binding strength of the scale. - Abstract: This paper investigates the effect of the rare earth element yttrium on the rupture behaviour of the oxide scale on the silicon-containing heat-resistant alloy during cooling. After 10 h of oxidation, yttrium is found to facilitate the formation of internal oxides (silica) at the scale-matrix interface. Due to the twinning observed by scanning transmission electron microscopy (STEM) in silica, the critical strain value for the scale failure can be dramatically improved, and the formation of cracks at the scale-matrix interface is inhibited.

Bio sorption of some Rare Earth Elements and Yttrium by Gram Positive and Gram Negative Bacteria

International Nuclear Information System (INIS)

Ibrahim, H.A.

2012-01-01

The separate bio sorption of the REEs La, Sm, Eu and Dy together with yttrium upon the Gram positive bacteria Bacillus subtilis (B.subtilis) and Bacillus Licheniformis (B. Licheniformis),the Gram negative bacterium Escherichia coli (E. coli ) and Saccharomyces cervisiae (Yeast) was studied. The revelant factors of ph 1-6, contact time (30-180 min), the initial rare earth concentration (50-200 mg/l) have been studied. The amount of the accumulated element was strongly affected by its concentration.In addition, bio sorptive fractionation of Y and the studied REEs from a solution containing a mixture of these elements was also studied. From the obtained data, it was found that Langmuir isotherm model for both B.licheniformis and E.coli gives a best fit for the studied elements over the working range of concentration (50-200 mg/I). Transmission electron microscopy exhibited accumulation throughout the bacterial cell with some granular deposits in both the cell periphery and cytoplasm

(Gd1−xErx)5Si2Ge2 compounds

Indian Academy of Sciences (India)

Gd metal (3 N) by arc melting, and then annealed at 1523 K (3 h). The phase, microstructure, Curie ... The temperature of magnetic transition decreases linearly from 281 K to 177 K with the increase of Er content from x = 0–0·2. ... Gd5Si2Ge2 serial compounds, different rare earth elements substituted for Gd in Gd5(Six ...

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

International Nuclear Information System (INIS)

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

1995-01-01

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

Luminescence and scintillation response of YGd.sub.2./sub.Al.sub.2./sub.Ga.sub.3./sub.O.sub.12./sub.:Ce and LuGd.sub.2./sub.Al.sub.2./sub.Ga.sub.3./sub.O.sub.12./sub.:Ce scintillators

Czech Academy of Sciences Publication Activity Database

Chewpraditkul, Wa.; Pattanaboonmee, N.; Chewpraditkul, W.; Kamada, K.; Yoshikawa, A.; Nikl, Martin

2016-01-01

Roč. 90, Jul (2016), s. 153-156 ISSN 1350-4487. [International Conference on Luminescent Detectors and Transformers of Ionizing Radiation (LUMDETR). Tartu (Estonsko), 20.09.2015-25.09.2015] R&D Projects: GA ČR GAP204/12/0805 Institutional support: RVO:68378271 Keywords : YGd 2 Al 2 Ga 3 O 12 :Ce * LuGd 2 Al 2 Ga 3 O 12 :Ce * light yield * luminescence * scintillation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.442, year: 2016

Prospective elemental analysis of algal biomass accumulated at the dominican republic Shores during 2015

International Nuclear Information System (INIS)

Fernández, Fernando; Boluda, Carlos José; Olivera, Jesús; Gómez, Luis Alberto Guillermo Bolivar; Gómez, Enmanuel Echavarría Aris Mendis

2017-01-01

The massive accumulation and decomposition of the Sargassum natans and Sargassum fluitans brown seaweeds on the Antillean shores has become a major problem in Central America and the Caribbean, seriously affecting tourism. However, the value of the algal biomass should not be underestimated, since it contains bioactive compounds with industrial application or in a more traditional use as fertilizers. On the other hand, seaweeds have the ability to bioaccumulate toxic metals such as Hg, Pb, Cd, Ni and Cr, among others. In order to ensure the safety of this biological material in its possible applications, it has been carried out a prospective study of the content in different transition metals and rare earths. Slightly elevated mercury levels were detected, which could limit the use of biomass. The content in Sc (scandium), Y (yttrium) and 14 lanthanides (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu), collectively known as rare earths, was also determined, being higher than in the ocean levels. This is consistent with the hypothesis that places the origin of these algae to more southern latitudes, where they proliferate in the shelter of the mouth of large rivers. (author)

PROSPECTIVE ELEMENTAL ANALYSIS OF ALGAL BIOMASS ACUMULATED AT THE DOMINICAN REPUBLIC SHORES DURING 2015

Directory of Open Access Journals (Sweden)

Fernando Fernández

2017-01-01

Full Text Available The massive accumulation and decomposition of the Sargassum natans and Sargassum fluitans brown seaweeds on the Antillean shores has become a major problem in Central America and the Caribbean, seriously affecting tourism. However, the value of the algal biomass should not be underestimated, since it contains bioactive compounds with industrial application or in a more traditional use as fertilizers. On the other hand, seaweeds have the ability to bioaccumulate toxic metals such as Hg, Pb, Cd, Ni and Cr, among others. In order to ensure the safety of this biological material in its possible applications, it has been carried out a prospective study of the content in different transition metals and rare earths. Slightly elevated mercury levels were detected, which could limit the use of biomass. The content in Sc (scandium, Y (yttrium and 14 lanthanides (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, collectively known as rare earths, was also determined, being higher than in the ocean levels. This is consistent with the hypothesis that places the origin of these algae to more southern latitudes, where they proliferate in the shelter of the mouth of large rivers.

Comparison of the scintillation and luminescence properties of the (Lu1−xGdx)2SiO5:Ce single crystal scintillators

International Nuclear Information System (INIS)

Jarý, V; Mihóková, E; Mareš, J A; Beitlerová, A; Nikl, M; Kurtsev, D; Sidletskiy, O

2014-01-01

We provide a systematic comparison of the scintillation and luminescence properties, including emission mechanisms, of the highly efficient cerium-doped scintillators lutetium-(gadolinium) orthosilicates Lu 2 (SiO 4 )O (LSO), (Lu 1−x Gd x ) 2 (SiO) 4 O(LGSO) and Gd 2 (SiO 4 )O (GSO). Determined characteristics manifest an advantage of LGSO:Ce with respect to both LSO:Ce and GSO:Ce for scintillator applications around room temperature. This is thanks to combined fast decay (faster than both limit compositions) high light yield, similar to that of LSO:Ce (twice higher than GSO:Ce) and low afterglow, similar to that of GSO:Ce (almost two orders of magnitude lower than LSO:Ce). High temperature applications do not, however, seem to be a suitable option for LGSO:Ce due to evidenced thermal ionization of both Ce1 and Ce2 centres above room temperature. (paper)

High pressure studies of magnetic, electronic, and local structure properties in the rare-earth orthoferrites RFeO3 (R = Nd, Lu)

International Nuclear Information System (INIS)

Gavriliuk, A.G.; Stepanov, G.N.; Lyubutin, I.S.; Stepin, A.S.; Trojan, I.A.; Sidorov, V.A.

2000-01-01

The high pressure modification of the electronic structure, magnetic properties, and local crystal structure have been studied in the rare-earth RFeO 3 (R=Nd, Lu) orthoferrites in both pure single crystals and polycrystalline samples doped with Sn. The pressure dependences of the unit cell parameters, Neel temperatures, supertransferred hyperfine magnetic fields at tin nuclei H Sn , and the optical absorption edge have been obtained. The relations of the obtained values with the geometry of exchange interactions were analyzed

Cation sorption at the smectite edges: From transition metals to Y and Lu

International Nuclear Information System (INIS)

Schlegel, M.L.

2007-01-01

Complete text of publication follows: Introduction: Clay minerals can adsorb trace elements in soils and weathering formations, a sorption property which is also a key-point for the use of clay materials in nuclear waste repositories. Retention can occur either by adsorption on the clay basal plane or at the layer edges, depending on physicochemical conditions. Building on previous identification of sorption sites of transition metals [1-3], this study shows how the geometry of Y and Lu surface complexes on layer edges of clay minerals can be identified. Materials and methods: Suspensions of purified clay minerals (hectorite or Al-montmorillonite, 2 and 1 g/L, respectively) were reacted in 0.5 M NaCl at pH 6 (Al-montmorillonite) and 7 (hectorite) with sorbates at concentrations of 50 μM (Y) and 100 μM (Lu). Self-supporting films of reacted clay minerals were obtained by slowly filtering suspension aliquots on cellulose nitrate filters. Yttrium K-edge and Lu L3-edge polarized EXAFS (PEXAFS) spectra of the self-supporting films were collected in fluorescence mode on the FAME beamline (ESRF, France). PEXAFS data were reduced, and analyzed using standard procedures. Results and interpretation: Small but significant angular dependences were observed for all P-EXAFS data, meaning that the Y and Lu binding environments are anisotropic. Coordination spheres of 7 O at 2.36 Angstroms and 8 O at 2.27 Angstroms, were observed for Y and Lu, respectively, comparable with d(Ln-O) distances measured by EXAFS spectroscopy [4]. Lutetium sorbed on Al-montmorillonite was surrounded by an Al-shell at 3.35 Angstroms, consistent with Lu sharing edges with Al octahedra and partially incorporated in a gibbsite-like interlayer. Both Y and Lu sorbed on hectorite were surrounded by cationic shells. Modelling of these cationic contributions yielded one out-of-plane Si/Mg shell at 3.16 Angstroms (Y) or 3.04 Angstroms (Lu), and two in-plane (Mg/Si) shells at 3.50, and 3.97 Angstroms for Y, or

Cation sorption at the smectite edges: From transition metals to Y and Lu

Energy Technology Data Exchange (ETDEWEB)

Schlegel, M.L. [CEA/DANS/DPC/SCP Lab React Surfaces and Interfaces, F-91191 Gif Sur Yvette (France)

2007-07-01

Complete text of publication follows: Introduction: Clay minerals can adsorb trace elements in soils and weathering formations, a sorption property which is also a key-point for the use of clay materials in nuclear waste repositories. Retention can occur either by adsorption on the clay basal plane or at the layer edges, depending on physicochemical conditions. Building on previous identification of sorption sites of transition metals [1-3], this study shows how the geometry of Y and Lu surface complexes on layer edges of clay minerals can be identified. Materials and methods: Suspensions of purified clay minerals (hectorite or Al-montmorillonite, 2 and 1 g/L, respectively) were reacted in 0.5 M NaCl at pH 6 (Al-montmorillonite) and 7 (hectorite) with sorbates at concentrations of 50 {mu}M (Y) and 100 {mu}M (Lu). Self-supporting films of reacted clay minerals were obtained by slowly filtering suspension aliquots on cellulose nitrate filters. Yttrium K-edge and Lu L3-edge polarized EXAFS (PEXAFS) spectra of the self-supporting films were collected in fluorescence mode on the FAME beamline (ESRF, France). PEXAFS data were reduced, and analyzed using standard procedures. Results and interpretation: Small but significant angular dependences were observed for all P-EXAFS data, meaning that the Y and Lu binding environments are anisotropic. Coordination spheres of 7 O at 2.36 Angstroms and 8 O at 2.27 Angstroms, were observed for Y and Lu, respectively, comparable with d(Ln-O) distances measured by EXAFS spectroscopy [4]. Lutetium sorbed on Al-montmorillonite was surrounded by an Al-shell at 3.35 Angstroms, consistent with Lu sharing edges with Al octahedra and partially incorporated in a gibbsite-like interlayer. Both Y and Lu sorbed on hectorite were surrounded by cationic shells. Modelling of these cationic contributions yielded one out-of-plane Si/Mg shell at 3.16 Angstroms (Y) or 3.04 Angstroms (Lu), and two in-plane (Mg/Si) shells at 3.50, and 3.97 Angstroms for Y

Study of quantitative analysis of rare earth elements (Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) in soil samples by inductively couple plasma mass spectrometry

International Nuclear Information System (INIS)

Truong Duc Toan; Nguyen Giang; Vo Tran Quang Thai; Do Tam Nhan; Nguyen Le Anh; Nguyen Viet Duc; Luong Thi Tham; Truong Thi Phuong Mai

2015-01-01

Method for the determination of 16 rare earth elements (REEs) in soil samples without separating by inductively coupled plasma mass spectrometry (ICP-MS) has been studied at Dalat Nuclear Research Institute. The optimal conditions for ICP-MS NexION 300X with three modes: Standard, Collision (KED), and Reaction (DRC) have been studied on the Montana II soil reference material. The result analysis shows that: DRC mode only gives good analysis result for Sc, Y, La, Ce, Pr, Nd, Tm, Yb, and Lu; Standard mode exhibits good analysis results for all elements with error from 1.2 - 29.0% and KED mode is the best one with error less than 15%. The concentrations of elements in the soil samples of Cau Dat, Bao Loc, and Da Lat were determined, which concentrations of REEs in soil samples of Cau Dat are higher than that of the other areas in Lam Dong Province. (author)

Effect of rare-earth-based nanoparticles on the erythrocyte osmotic adaptation

Directory of Open Access Journals (Sweden)

О. К. Пакулова

2017-09-01

Full Text Available Rare-earth-based nanoparticles (REB NPs have been employed in molecular and cell biology due to their unique features. However, their interaction with biosystems and the influence on cell functioning are poorly understood. In this study effect of REB NPs (composed of dielectric nanocrystalls of cerium dioxide and orthovanadates of gadolinium and yttrium with different form-factor as well as REB NPs-cholesterol complexes on the adaptation of human erythrocytes to hypertonic lysis (4 M NaCl has been evaluated spectrophotometrically. It appeared that the degree of cell damage in the presence of REP NPs under hyperosmotic conditions varied with geometric parameters of REB NPs. Specifically: i ultra-small (2 nm spherical CeO2 or GdYVO4:Eu3+ NPs, penetrating through the plasma membrane, ii grain-like (8´30 nm GdVO4:Eu3+ NPs, adsorbed on the membrane surface, iii and spherical GdYVO4:Eu3+ NPs-cholesterol complexes promoted cell adaptation to hypertonic lysis. Furthermore, the composition of nanoparticles affected their stabilizing effect on the cells. E.g., orthovanadate NPs at 0.1 g/l had the highest antihemolytic activity after short preincubation, while cerium dioxide NPs showed the same effect after prolonged preincubation. In conclusion, REB NPs promoted hyperosmotic cell adaptation by the two different mechanisms, viz. membrane stabilization by the adsorption on the cell surface and/or penetration into the cell.

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

Science.gov (United States)

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

2011-08-01

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

Faraday effect in Gd3Al5O12 and Gd3Ga5O12 rare earth garnets

International Nuclear Information System (INIS)

Valiev, U.V.; Klochkov, A.A.; Popov, A.I.; Sokolov, Y.B.

1989-01-01

The dispersion of the Faraday rotation of the garnets Gd 3 Ga 5 O 12 and Gd 3 Al 5 O 12 in the 440--700-nm region in the 85--295-K temperature interval and the spectral dependence of the Faraday effect in the garnets Y 3 Ga 5 O 12 and Y 3 Al 5 O 12 for wavelengths from 250 to 700 nm are investigated. The contributions to the Faraday rotation caused by the Gd 3+ ions and the diamagnetic lattice of the garnets are separated

Spin Hall magnetoresistance in the non-collinear ferrimagnet GdIG close to the compensation temperature.

Science.gov (United States)

Dong, Bo-Wen; Cramer, Joel; Ganzhorn, Kathrin; Yuan, H Y; Guo, Er-Jia; Goennenwein, Sebastian T B; Kläui, Mathias

2018-01-24

We investigate the spin Hall magnetoresistance (SMR) in a gadolinium iron garnet (GdIG)/platinum (Pt) heterostructure by angular dependent magnetoresistance measurements. The magnetic structure of the ferromagnetic insulator GdIG is non-collinear near the compensation temperature, while it is collinear far from the compensation temperature. In the collinear regime, the SMR signal in GdIG is consistent with the usual [Formula: see text] relation well established in the collinear magnet yttrium iron garnet, with [Formula: see text] the angle between magnetization and spin Hall spin polarization direction. In the non-collinear regime, both an SMR signal with inverted sign and a more complex angular dependence with four maxima are observed within one sweep cycle. The number of maxima as well as the relative strength of different maxima depend strongly on temperature and field strength. Our results evidence a complex SMR behavior in the non-collinear magnetic regime that goes beyond the conventional formalism developed for collinear magnetic structures.

Rare earth-ruthenium-magnesium intermetallics

Energy Technology Data Exchange (ETDEWEB)

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

2017-07-01

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

Magnetic properties of amorphous alloys of Fe with La, Lu, Y, and Zr

International Nuclear Information System (INIS)

Heiman, N.; Kazama, N.

1979-01-01

In order to study the systematics of the Fe-Fe exchange in amorphous rare-earth--Fe alloys, without the complications associated with the magnetic characteristics of the rare-earth elements, amorphous films of Fe alloyed with La, Lu, Y, and Zr have been prepared with a wide range of Fe concentrations. Magnetization and Moessbauer-effect measurements were made. The magnetic properties of the alloys depended critically on the choice of rare earth (or rare-earth-like element). YFe and LuFe alloys were found to have spin-glass characteristics while LaFe and ZrFe alloys were found to be ferromagnetic, but with evidence that exchange fluctuations were nearly as large as the average exchange. Thus the nature of the Fe-Fe exchange interaction depends critically upon the species of the rare earth. The most important parameter in determining the magnetic behavior of these alloys appears to be the size of the rare-earth atom, with large rare-earth atoms resulting in a smaller ratio of exchange fluctuations to exchange. The same dependence of the magnetic properties upon rare-earth size appears to be important in the case of magnetic-rare-earth atoms; however, the effect of rare-earth--Fe exchange also becomes important and these effects are discussed

Diffusion of hydrogen in yttrium

International Nuclear Information System (INIS)

Vorobyov, V.V.; Ryabchikov, L.N.

1966-01-01

In this work the diffusion coefficients of hydrogen in yttrium were determined from the rate at which the hydrogen was released from yttrium samples under a vacuum at temperatures of 450 to 850 0 C and from the quantity of hydrogen retained by yttrium at hydrogen pressures below 5 x 10 - 4 mm Hg in the same temperature range

Rare earth-based quaternary Heusler compounds MCoVZ (M = Lu, Y; Z = Si, Ge with tunable band characteristics for potential spintronic applications

Directory of Open Access Journals (Sweden)

Xiaotian Wang

2017-11-01

Full Text Available Magnetic Heusler compounds (MHCs have recently attracted great attention since these types of material provide novel functionalities in spintronic and magneto-electronic devices. Among the MHCs, some compounds have been predicted to be spin-filter semiconductors [also called magnetic semiconductors (MSs], spin-gapless semiconductors (SGSs or half-metals (HMs. In this work, by means of first-principles calculations, it is demonstrated that rare earth-based equiatomic quaternary Heusler (EQH compounds with the formula MCoVZ (M = Lu, Y; Z = Si, Ge are new spin-filter semiconductors with total magnetic moments of 3 µB. Furthermore, under uniform strain, there are physical transitions from spin-filter semiconductor (MS → SGS → HM for EQH compounds with the formula LuCoVZ, and from HM → SGS → MS → SGS → HM for EQH compounds with the formula YCoVZ. Remarkably, for YCoVZ EQH compounds there are not only diverse physical transitions, but also different types of spin-gapless feature that can be observed with changing lattice constants. The structural stability of these four EQH compounds is also examined from the points of view of formation energy, cohesive energy and mechanical behaviour. This work is likely to inspire consideration of rare earth-based EQH compounds for application in future spintronic and magneto-electronic devices.

Yttrium recovery from primary and secondary sources: A review of main hydrometallurgical processes

Energy Technology Data Exchange (ETDEWEB)

Innocenzi, Valentina, E-mail: valentina.innocenzi1@univaq.it [Department of Industrial Engineering, of Information and Economy, University of L’Aquila, Via Giovanni Gronchi 18, Zona industriale di Pile, 67100 L’Aquila (Italy); De Michelis, Ida [Department of Industrial Engineering, of Information and Economy, University of L’Aquila, Via Giovanni Gronchi 18, Zona industriale di Pile, 67100 L’Aquila (Italy); Kopacek, Bernd [SAT, Austrian Society for Systems Engineering and Automation, Gurkasse 43/2, A-1140 Vienna (Austria); Vegliò, Francesco [Department of Industrial Engineering, of Information and Economy, University of L’Aquila, Via Giovanni Gronchi 18, Zona industriale di Pile, 67100 L’Aquila (Italy)

2014-07-15

Highlights: • Review of the main hydrometallurgical processes to recover yttrium. • Recovery of yttrium from primary sources. • Recovery of yttrium from e-waste and other types of waste. - Abstract: Yttrium is important rare earths (REs) used in numerous fields, mainly in the phosphor powders for low-energy lighting. The uses of these elements, especially for high-tech products are increased in recent years and combined with the scarcity of the resources and the environmental impact of the technologies to extract them from ores make the recycling waste, that contain Y and other RE, a priority. The present review summarized the main hydrometallurgical technologies to extract Y from ores, contaminated solutions, WEEE and generic wastes. Before to discuss the works about the treatment of wastes, the processes to retrieval Y from ores are discussed, since the processes are similar and derived from those already developed for the extraction from primary sources. Particular attention was given to the recovery of Y from WEEE because the recycle of them is important not only for economical point of view, considering its value, but also for environmental impact that this could be generated if not properly disposal.

Optical, Structural and Paramagnetic Properties of Eu-Doped Ternary Sulfides ALnS2 (A = Na, K, Rb; Ln = La, Gd, Lu, Y

Directory of Open Access Journals (Sweden)

Vítězslav Jarý

2015-10-01

Full Text Available Eu-doped ternary sulfides of general formula ALnS2 (A = Na, K, Rb; Ln = La, Gd, Lu, Y are presented as a novel interesting material family which may find usage as X-ray phosphors or solid state white light emitting diode (LED lighting. Samples were synthesized in the form of transparent crystalline hexagonal platelets by chemical reaction under the flow of hydrogen sulfide. Their physical properties were investigated by means of X-ray diffraction, time-resolved photoluminescence spectroscopy, electron paramagnetic resonance, and X-ray excited fluorescence. Corresponding characteristics, including absorption, radioluminescence, photoluminescence excitation and emission spectra, and decay kinetics curves, were measured and evaluated in a broad temperature range (8–800 K. Calculations including quantum local crystal field potential and spin-Hamiltonian for a paramagnetic particle in D3d local symmetry and phenomenological model dealing with excited state dynamics were performed to explain the experimentally observed features. Based on the results, an energy diagram of lanthanide energy levels in KLuS2 is proposed. Color model xy-coordinates are used to compare effects of dopants on the resulting spectrum. The application potential of the mentioned compounds in the field of white LED solid state lighting or X-ray phosphors is thoroughly discussed.

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

Directory of Open Access Journals (Sweden)

James R. Hein

2016-08-01

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

Carbon footprint assessment of recycling technologies for rare earth elements: A case study of recycling yttrium and europium from phosphor.

Science.gov (United States)

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.

Spectral properties of hydrothermally-grown Nd:LuAG, Yb:LuAG, and Yb:Lu{sub 2}O{sub 3} laser materials

Energy Technology Data Exchange (ETDEWEB)

Brown, David C., E-mail: DBrown@snakecreeklasers.com [Snake Creek Lasers LLC, Friendsville, PA 18818 (United States); McMillen, Colin D.; Moore, Cheryl; Kolis, Joseph W. [Department of Chemistry and Center for Optical Materials Science and Engineering Technologies, Clemson University, Clemson, SC 29634-0973 (United States); Envid, Victoria [Snake Creek Lasers LLC, Friendsville, PA 18818 (United States)

2014-04-15

We have investigated the hydrothermal growth of, and spectrally characterized, the lutetium based laser materials Nd:LuAG, Yb:LuAG, and Yb:Lu{sub 2}O{sub 3}. Absorption cross-section data are presented for Nd:LuAG at 83, 175, and 295 K. Absorption cross-section data was also obtained for Yb:LuAG at 83, 175, and 295 K; the 295 K data was used to generate emission cross-sections using the method of reciprocity. For Yb:Lu{sub 2}O{sub 3}, we present absorption cross-sections at 295 K as well as emission cross-sections derived using reciprocity. -- Highlights: • We present spectral properties for hydrothermally-grown laser crystals. • Absorption cross-section data are presented for Nd:LuAG and Yb:LuAG at 83, 175, and 295 K. • Emission cross-sections are presented for Yb:LuAG at 295 K derived by reciprocity. • We present absorption cross-sections at 295 K as well as emission cross-sections derived using reciprocity for the laser material Yb:Lu{sub 2}O{sub 3}.

Texture and deformation mechanism of yttrium

International Nuclear Information System (INIS)

Adamesku, R.A.; Grebenkin, S.V.; Stepanenko, A.V.

1992-01-01

X-ray pole figure analysis was applied to study texture and deformation mechanism in pure and commercial polycrystalline yttrium on cold working. It was found that in cast yttrium the texture manifected itself weakly enough both for pure and commercial metal. Analysis of the data obtained made it possible to assert that cold deformation of pure yttrium in the initial stage occurred mainly by slip the role of which decreased at strains higher than 36%. The texture of heavily deformed commercial yttrium contained two components, these were an 'ideal' basic orientation and an axial one with the angle of inclination about 20 deg. Twinning mechanism was revealed to be also possible in commercial yttrium

Synthesis, crystal structure, and physical properties of the Gd{sub 3}BiO{sub 3} and Gd{sub 8}Bi{sub 3}O{sub 8} phases

Energy Technology Data Exchange (ETDEWEB)

Forbes, Scott; Yuan, Fang [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1 (Canada); Kosuda, Kosuke; Kolodiazhnyi, Taras [Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Mozharivskyj, Yurij, E-mail: mozhar@mcmaster.ca [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1 (Canada)

2016-01-15

The second and third known rare-earth bismuthide oxides, Gd{sub 3}BiO{sub 3} and Gd{sub 8}Bi{sub 3}O{sub 8}, have been discovered via high temperature reactions at 1300 °C. Like its Gd–Sb–O counterparts, the Gd{sub 3}BiO{sub 3} and Gd{sub 8}Bi{sub 3}O{sub 8} phases crystallize in the monoclinic C2/m space group, with the latter containing disordered Bi atoms along the b direction of the unit cell. Unlike the RE{sub 8}Sb{sub 3}O{sub 8} series, the formation of the Gd{sub 3}BiO{sub 3} phase does not necessarily precede the formation of Gd{sub 8}Bi{sub 3}O{sub 8}, which is likely due to the difficulty of accommodating bismuth in the RE–O framework due to its larger size. Physical property measurements performed on a pure Gd{sub 8}Bi{sub 3}O{sub 8} sample reveal semiconducting behavior. Although electronic structure calculations predict metallic behavior due to an unbalanced electron count, the semiconducting behavior originates from the Anderson localization of the Bi p states near the Fermi level as a result of atomic disorder. - Graphical abstract: Reaction of GdBi and Gd{sub 2}O{sub 3} at high temperatures yields Gd–Bi–O phases. - Highlights: • Gd{sub 3}BiO{sub 3} and Gd{sub 8}Bi{sub 3}O{sub 8}, the second and third rare-earth bismuthide oxides, have been discovered. • Gd{sub 3}BiO{sub 3} and Gd{sub 8}Bi{sub 3}O{sub 8} are isostructural with RE{sub 3}SbO{sub 3} and RE{sub 8}Sb{sub 3}O{sub 8}. • Gd{sub 8}Bi{sub 3}O{sub 8} displays semiconducting behavior despite an unbalanced electron count. • Anderson localization of Bi p states results in semiconducting behavior in Gd{sub 8}Bi{sub 3}O{sub 8}.

Sc, Y, La-Lu - Rare Earth Elements

International Nuclear Information System (INIS)

Anon.

1987-01-01

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

Emission bands of phosphorus and calculation of band structure of rare earth phosphides

International Nuclear Information System (INIS)

Al'perovich, G.I.; Gusatinskij, A.N.; Geguzin, I.I.; Blokhin, M.A.; Torbov, V.I.; Chukalin, V.I.; AN SSSR, Moscow. Inst. Novykh Khimicheskikh Problem)

1977-01-01

The method of x-ray emission spectroscopy has been used to investigate the electronic structure of monophosphides of rare-earth metals (REM). The fluorescence K bands of phosphorus have been obtained in LaP, PrP, SmP, GdP, TbP, DyP, HoP, ErP, TmP, YbP, and LuP and also the Lsub(2,3) bands of phosphorus in ErP, TmP, YbP, and LuP. Using the Green function technique involving the muffin-tin potential, the energy spectrum for ErP has been calculated in the single-electron approximation. The hystogram of electronic state distribution N(E) is compared with the experimental K and Lsub(2,3) bands of phosphorus in ErP. The agreement between the main details of N(E) and that of x-ray spectra allows to state that the model used provides a good description of the electron density distribution in crystals of REM monophosphides. In accordance with the character of the N(E) distribution the compounds under study are classified as semimetals or semiconductors with a very narrow forbidden band

Gadolinium scandium germanide, Gd2Sc3Ge4

Directory of Open Access Journals (Sweden)

Sumohan Misra

2009-04-01

Full Text Available Gd2Sc3Ge4 adopts the orthorhombic Pu5Rh4-type structure. The crystal structure contains six sites in the asymmetric unit: two sites are statistically occupied by rare-earth atoms with Gd:Sc ratios of 0.967 (4:0.033 (4 and 0.031 (3:0.969 (3, one site (.m. symmetry is occupied by Sc atoms, and three distinct sites (two of which with .m. symmetry are occupied by Ge atoms. The rare-earth atoms form two-dimensional slabs with Ge atoms occupying the trigonal-prismatic voids.

Temperature-dependent nonradiative energy transfer from Gd3+ to Ce3+ ions in co-doped LuAG: Ce,Gd garnet scintillators

Czech Academy of Sciences Publication Activity Database

Onderišinová, Z.; Kucera, M.; Hanus, M.; Nikl, Martin

2015-01-01

Roč. 167, Nov (2015), s. 106-113 ISSN 0022-2313 R&D Projects: GA ČR GAP204/12/0805 Institutional support: RVO:68378271 Keywords : scintillator * garnet * Gd 3+ * Ce 3+ * energy transfer Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.693, year: 2015

Ab initio Assessment of Bi1-xRExCuOS (RE=La, Gd, Y, Lu) Solid Solution as Semiconductor for Photochemical Water Splitting

KAUST Repository

Lardhi, Sheikha F.

2017-04-12

The investigation of BiCuOCh (Ch = S, Se and Te) semiconductors family for thermoelectric or photovoltaic materials is an increasing topic of research. These materials can also be considered for photochemical water splitting if one representative having a bandgap, Eg, around 2 eV can be developed. With this aim, we simulated the solid solution Bi1-xRExCuOS (RE = Y, La, Gd and Lu) from pure BiCuOS (Eg~1.1 eV) to pure RECuOS compositions (Eg~2.9 eV) by DFT calculations based on the HSE06 range-separated hybrid functional with inclusion of spin-orbit coupling. Starting from the thermodynamic stability of the solid solution, a large variety of properties were computed for each system including bandgap, dielectric constants, effective masses and exciton binding energies. We discussed the variation of these properties based on the relative organization of Bi and RE atoms in their common sublattice to offer a physical understanding of the influence of the RE doping of BiCuOS. Some compositions were found to give appropriate properties for water splitting application. Furthermore, we found that at low RE fractions the transport properties of BiCuOS are improved that can find applications beyond water splitting.

Ab initio Assessment of Bi1-xRExCuOS (RE=La, Gd, Y, Lu) Solid Solution as Semiconductor for Photochemical Water Splitting

KAUST Repository

Lardhi, Sheikha F.; Curutchet, Antton; Cavallo, Luigi; Harb, Moussab; Le Bahers, Tangui

2017-01-01

The investigation of BiCuOCh (Ch = S, Se and Te) semiconductors family for thermoelectric or photovoltaic materials is an increasing topic of research. These materials can also be considered for photochemical water splitting if one representative having a bandgap, Eg, around 2 eV can be developed. With this aim, we simulated the solid solution Bi1-xRExCuOS (RE = Y, La, Gd and Lu) from pure BiCuOS (Eg~1.1 eV) to pure RECuOS compositions (Eg~2.9 eV) by DFT calculations based on the HSE06 range-separated hybrid functional with inclusion of spin-orbit coupling. Starting from the thermodynamic stability of the solid solution, a large variety of properties were computed for each system including bandgap, dielectric constants, effective masses and exciton binding energies. We discussed the variation of these properties based on the relative organization of Bi and RE atoms in their common sublattice to offer a physical understanding of the influence of the RE doping of BiCuOS. Some compositions were found to give appropriate properties for water splitting application. Furthermore, we found that at low RE fractions the transport properties of BiCuOS are improved that can find applications beyond water splitting.

Apparent and partial molal heat capacities of aqueous rare earth nitrate solutions at 250C

International Nuclear Information System (INIS)

Spedding, F.H.; Baker, J.L.; Walters, J.P.

1979-01-01

Specific heats of aqueous solutions of the trinitrates of La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu were measured from 0.1 m to saturation at 25 0 C. Apparent molal heat capacities, phi/sub cp/, were calculated for these solutions, and empirical polynomial equations were obtained which expressed phi/sub cp/ as a function of m/sup 1/2/ for each salt. The partial molal heat capacities of the solvent, anti C 1 /sub p/, and solute, anti C 2 /sub p/, were calculated from these equations. Unlike chloride and perchlorate data reported earlier, values of anti C 1 /sub p/ for nitrate solutions across the rare earth series did not show a two series effect. Instead, anti C 1 /sub p/ values at lower concentrations (0.5 and 1.0 m) appear correlated with reported first formation constants for rare earth-nitrate complexes. 31 references, 9 figures, 2 tables

Optical properties of ytterbium-doped yttrium oxide ceramics

Energy Technology Data Exchange (ETDEWEB)

Solomonov, V.I.; Maksimov, R.N. [Institute of Electrophysics UrB RAS, Amundsena 106, 620016 Ekaterinburg (Russian Federation); Ural Federal University Named After the First President of Russia B.N. Yeltsin, Mira 19, 620002 Ekaterinburg (Russian Federation); Osipov, V.V.; Shitov, V.A.; Lipchak, A.I. [Institute of Electrophysics UrB RAS, Amundsena 106, 620016 Ekaterinburg (Russian Federation)

2017-05-15

Ytterbium-doped yttrium oxide (Yb:Y{sub 2}O{sub 3}) transparent ceramics with different sintering additives (Lu{sub 2}O{sub 3}, Sc{sub 2}O{sub 3}, CeO{sub 2}, ZrO{sub 2}, or HfO{sub 2}) were fabricated using nanopowders produced by laser ablation. Transmission and photoluminescence spectra of the obtained ceramics were investigated at room temperature. Highest in-line transmittance was over 80% at the wavelength of 1060 nm for 2 mm thick Yb:Y{sub 2}O{sub 3} ceramics with zirconium and hafnium. Divalent Yb ions with the ground state electron configuration 4f{sup 13}6s were revealed. The absorption and emission bands caused by s <-> s transitions of these ions were observed in the IR spectral range of Yb{sup 3+} ions. The superposition of both Yb{sup 3+} and Yb{sup 2+} emission bands leads to an effective broadening of the whole luminescence band. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Highly efficient channel waveguide lasers at 1 µm and 2 µm in refractive-index-engineered potassium double tungstates

NARCIS (Netherlands)

van Dalfsen, Koop; Geskus, D.; García Blanco, Sonia Maria; Pollnau, Markus

Epitaxial growth of rare-earth-ion-activated KY(1-x-y)Gd(x)Lu(y)(WO4)2 co-doped thin layers onto KY(WO4)2 substrates has enabled lattice-matched waveguides with high refractive-index contract and large variation of the active rare-earth-ion concentration. In Yb3+-activated micro-structured channel

Spectroscopic study of magnetic phase transitions and magnetic structures in rare earth ferroborates RFe3(BO3)4 (R = Y, Er, Tb, Gd)

International Nuclear Information System (INIS)

Popova, M.N.; Chukalina, E.P.; Stanislavchuk, T.N.; Bezmaternykh, L.N.

2006-01-01

One investigated into the absorption spectra of RFe 3 (BO 3 ) 4 , R=Y, Er, Tb, Gd rare earth borate single crystals containing erbium (1%) introduced to serve as a probe. On the basis of the temperature dependences of Er 3+ ion spectral line splittings one determined the values of the magnetic ordering temperatures of Er, Tb and Gd ferroborates and the temperatures of the spin reoriented first order phase transition in GdFe 3 (BO 3 ) 4 :Er 3+ (1%). On the basis of comparison of the splitting values of Er 3+ ion ground state in RFe 3 (BO 3 ) 4 (R=Y, Er, Tb) and in GdFe 3 (BO 3 )4 compounds the magnetic structure of which is known one makes a concussion about the orientation of iron magnetic moments in the magneto-ordered state: a lightly planar structure is observed for YFe 3 (BO 3 ) 4 and ErFe 3 (BO 3 ) 4 and a lightly axial one - for TbFe 3 (BO 3 ) 4 . One discusses the role of R 3+ ion single ion anisotropy when determining the magnetic structure type in RFe 3 (BO 3 ) 4 [ru

Investigation of thermal expansion and compressibility of rare-earth orthovanadates using a dielectric chemical bond method.

Science.gov (United States)

Zhang, Siyuan; Zhou, Shihong; Li, Huaiyong; Li, Ling

2008-09-01

The chemical bond properties, lattice energies, linear expansion coefficients, and mechanical properties of ReVO 4 (Re = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, Y) are investigated systematically by the dielectric chemical bond theory. The calculated results show that the covalencies of Re-O bonds are increasing slightly from La to Lu and that the covalencies of V-O bonds in crystals are decreasing slightly from La to Lu. The linear expansion coefficients decrease progressively from LaVO 4 to LuVO 4; on the contrary, the bulk moduli increase progressively. Our calculated results are in good agreement with some experimental values for linear expansion coefficients and bulk moduli.

Radiation hardness of LuAG:Ce and LuAG:Pr scintillator crystals

CERN Document Server

Derdzyan, M V; Belsky, A; Dujardin, C; Lecoq, P; Lucchini, M; Ovanesyan, K L; Pauwels, K; Pedrini, C; Petrosyan, A G

2012-01-01

Single crystals of LuAG:Ce, LuAG:Pr and un-doped LuAG were grown by the vertical Bridgman method and studied for radiation hardness under gamma-rays with doses in the range 10-10(5) Gy (Co-60). A wide absorption band peaking at around 600 nm springs up in all three types of crystals after the irradiations. The second band peaking at around 375 nm appears in both LuAG:Pr and un-doped LuAG. Compositional variations have been done to reveal the spectral behavior of induced color centers in more detail and to understand their origin. Similarities in behavior of Yb2+ centers in as-grown garnets are found, indicating that radiation induced color centers can be associated with residual trace amounts of Yb present in the raw materials. Un-doped LuAG and LuAG:Ce demonstrate moderate radiation hardness (the induced absorption coefficients being equal to 0.05-0.08 cm(-1) for accumulated doses of 10(3)-10(4) Gy), while LuAG:Pr is less radiation hard. The ways to improve the radiation hardness are discussed.

UV-visible light photocatalytic properties of NaYF4:(Gd, Si)/TiO2 composites

Science.gov (United States)

Mavengere, Shielah; Kim, Jung-Sik

2018-06-01

In this study, a new novel composite photocatalyst of NaYF4:(Gd, Si)/TiO2 phosphor has been synthesized by two step method of solution combustion and sol-gel. The photocatalyst powders were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), UV-vis spectroscopy and photoluminescence (PL) spectroscopy. Raman spectroscopy confirmed the anatase TiO2 phase which remarkably increased with existence of yttrium silicate compounds between 800 cm-1 and 900 cm-1. Double-addition of Gd3+-Si4+ ions in NaYF4 host introduced sub-energy band levels with intense absorption in the ultraviolet (UV) light region. Photocatalytic activity was examined by exposing methylene blue (MB) solutions mixed with photocatalyst powders to 254 nm UV-C fluorescent lamp and 200 W visible lights. The UV and visible photocatalytic reactivity of the NaYF4:(Gd, 1% Si)/TiO2 phosphor composites showed enhanced MB degradation efficiency. The coating of NaYF4:(Gd, 1% Si) phosphor with TiO2 nanoparticles creates energy band bending at the phosphor/TiO2 interfaces. Thus, these composites exhibited enhanced absorption of UV/visible light and the separation of electron and hole pairs for efficient photocatalysis.

Distribution patterns of rare earth elements in various plant species

Energy Technology Data Exchange (ETDEWEB)

Wyttenbach, A.; Tobler, L.; Furrer, V. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1997-09-01

The elements La, Ce, Nd, Sm, Eu, Gd, Tb, Yb and Lu have been determined in 6 different plant species by neutron activation analysis. When the concentrations of each species were normalized to Norway spruce, smooth curves were obtained which revealed systematic inter-species differences. (author) 3 figs., 4 refs.

Distribution patterns of rare earth elements in various plant species

International Nuclear Information System (INIS)

Wyttenbach, A.; Tobler, L.; Furrer, V.

1997-01-01

The elements La, Ce, Nd, Sm, Eu, Gd, Tb, Yb and Lu have been determined in 6 different plant species by neutron activation analysis. When the concentrations of each species were normalized to Norway spruce, smooth curves were obtained which revealed systematic inter-species differences. (author) 3 figs., 4 refs

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

DEFF Research Database (Denmark)

Touborg, P.; Høg, J.

1974-01-01

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

Scintillation response of Ce3+ doped GdGa-LuAG multicomponent garnet films under e-beam excitation

Czech Academy of Sciences Publication Activity Database

Kučera, M.; Onderišinová, Z.; Bok, Jan; Hanuš, M.; Schauer, Petr; Nikl, Martin

169 Part B, JAN 2016 (2016), s. 674-677 ISSN 0022-2313 Institutional support: RVO:68081731 ; RVO:68378271 Keywords : multicomponent garnets * cathodoluminescence * LuAG:Ce * scintillation * liquidphaseepitaxy Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.686, year: 2016

Rare earth mineralogy of the Olympic Dam Cu-U-Au-Ag deposit, South Australia

International Nuclear Information System (INIS)

Lottermoser, B.G.; Day, A.

1993-01-01

Rare earth elements (REE) and yttrium accompany uranium and copper mineralisation within the polymetallic Olympic Dam deposit. The light and heavy rare earths tend to occur in different host minerals. Most of the light rare earths (LREE) are present as the essential structural constituents of LREE fluorocarbonates such bastnaesite and synchysite, or in phosphates such as florencite and monazite. Yttrium and the heavy rare earths (HREE) occur mostly as minor concentrations in the form of cation substitutions within uranium minerals such as uraninite and coffinite, as well as brannerite to a lesser extent. Selective dissolution of uraninite and coffinite during acid leaching leads to the liberation of yttrium and HREE from their host minerals, resulting in higher percentage extractions of HREE than LREE in uranium bearing leach liquors. LREE liberation is more restricted because only the synchysite dissolves to any significant extent, while bastnaesite is more difficult to dissolve. 9 refs., 2 figs

Determination of rare earth elements in seawater by inductively coupled plasma mass spectrometry with off-line column preconcentration using 2,6-diacetylpyridine functionalized Amberlite XAD-4

Energy Technology Data Exchange (ETDEWEB)

Karadas, Cennet [Department of Chemistry, Art and Science Faculty, Balikesir University, 10100 Balikesir (Turkey); Kara, Derya, E-mail: dkara@balikesir.edu.tr [Department of Chemistry, Art and Science Faculty, Balikesir University, 10100 Balikesir (Turkey); Fisher, Andrew [School of Geography, Earth and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth, Devon PL4 8AA (United Kingdom)

2011-03-18

An off-line column preconcentration technique using a micro-column of 2,6 diacetylpyridine functionalized Amberlite XAD-4 with inductively coupled plasma mass spectrometry (ICP-MS) as a means of detection has been developed. The aim of the method was to determine rare earth elements (REEs) (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) in seawater. Sample solutions (2-10 mL) were passed through the column which was then washed with ultra-pure water to remove residual matrix. The adsorbed cations on the resin were eluted by using 2 mL of 0.1 mol L{sup -1} HNO{sub 3} containing 10 ng mL{sup -1} indium as an internal standard. The eluent was analyzed for the metal concentrations using ICP-MS. Sample pH as well as the sample and eluent flow rates were optimized. The sorption capacity of resin was determined by the batch process, by equilibrating 0.05 g of the resin with solutions of 50 mL of 25 mg L{sup -1} of individual metal ions for 4 h at pH 6.0 at 26 deg. C. The sorption capacities for the resin were found to range between 47.3 {mu}mol g{sup -1} (for Lu) and 136.7 {mu}mol g{sup -1} (for Gd). Limits of detection (3{sigma}), without any preconcentration, ranged from 2 ng L{sup -1} to 10.3 ng L{sup -1} (for Tm and Lu respectively). The proposed method was applied to the determination of REEs in seawater and tap water samples.

Early history of Earth's crust-mantle system inferred from hafnium isotopes in chondrites

DEFF Research Database (Denmark)

Bizzarro, Martin; Haack, Henning; Rosing, M.

2003-01-01

for the chondrite-forming event. This ¿176 value indicates that Earth's oldest minerals were derived from melts of a mantle source with a time-integrated history of depletion rather than enrichment. The depletion event must have occurred no later than 320 Myr after planetary accretion, consistent with timing......The Lu to Hf decay series has been widely used to understand the nature of Earth's early crust-mantle system. The interpretation, however, of Lu-Hf isotope data requires accurate knowledge of the radioactive decay constant of Lu (¿176), as well as bulk-Earth reference parameters. A recent...

Crystal fields of dilute Tb, Dy, Ho, or Er in Lu obtained by magnetization measurements

International Nuclear Information System (INIS)

Touborg, P.; Hog, J.

1975-01-01

Magnetization measurements are reported on single crystals of dilute Tb, Dy, Ho, or Er in Lu. These measurements were performed in the temperature range 1.5--100 K and field range 0--6 T and include measurements of initial susceptibility, isothermal and isofield magnetization, and basal-plane anisotropy. The results show features similar to the corresponding Y-R alloys, where R is a rare earth. Crystal-field and molecular-field parameters could be unabiguously deduced from the experimental data. The effects of crystal-field level broadening were investigated and demonstrated for Ho. Comparison of the Y-R and Lu-R results makes possible an estimate of the crystal-field parameters in the pure-rare-earth metals

Magnetic anisotropy and neutron scattering studies of some rare earth metals

International Nuclear Information System (INIS)

Day, R.

1978-08-01

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

n-aminobenzoates of rare earths

International Nuclear Information System (INIS)

Efremova, G.I.; Buchkova, R.T.; Lapitskaya, A.V.; Pirkes, S.B.

1977-01-01

N-aminobenzoates of r.e.e. have been synthesized. Their composition corresponds to the general formula Me(C 6 H 4 NH 2 COO) 3 xnH 2 O, where Me stands for La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; n=1.2. The compounds obtained are identified by chemical analysis and roentgenographically. Their solubility products, which are values of the order of 10 -9 -10 -10 , are determined

Activation analysis of rare-earth elements in opium and cannabis samples

International Nuclear Information System (INIS)

Henke, G.

1977-01-01

Rare-earth concentrations in 65 Opium, Cannabis and Cannabis resin samples seized from various parts of the world were determined by destructive NAA. Because of the greater concentrations of Ca, P, K, Fe, Na and Si in plant materials, rare-earth elements were isolated after neutron irradiation and determined by gamma-spectrometry. The main steps of the method are: Preashing of 1 g Cannabis resin, 2.5 g Cannabis or 7.5 g Opium, respectively, in quartz ampoules (5 h, 500 deg C). Neutron irradiation, 24 h at 5x10 13 n cm -2 sec -1 . Cooling period 2-3 days. After addition of 0.1 μCi 139 Ce and rare-earth carriers wet ashing of irradiated samples with H 2 SO 4 /HNO 3 , followed by alternate addition of HNO 3 and H 2 O 2 (30%). Precipitation and removal of silicates, precipitation of fluorides, precipitation of hydroxides. Dissolution of hydroxides in HCl. Extraction with di-(2-ethylhexyl)phosphate (DEHP)/toluene and twice back-extraction of rare earths, gamma-spectrometry of HCl phase. Due to sample activity and half-life of nuclides, three measurements were made on each sample: 2 days (for La, Sm, Gd, Ho, Er, Yb); 14 days (for Nd, Lu) and 30 days after irradiation (for Ce, Eu, Tb). Great variations in absolute element concentrations, but only small significant differences of rare earth concentration ratios were found, indicating inconsiderable biogeochemical fractionation. The mean values of these ratios correspond to the relative abundances of the rare earths in the upper continental earth's crust. (T.G.)

Phase equilibria and crystalline structure of compounds in the Lu-Al and Lu-Cu-Al systems

International Nuclear Information System (INIS)

Kuz'ma, Yu.B.; Stel'makhovich, B.M.; Galamushka, L.I.

1992-01-01

Phase equilibria and crystal structure of compounds in Lu-Al and Lu-Cu-Al systems were studied. Existence of Lu 2 Al compound having the structure of the PbCl 2 type is ascertained. Diagram of phase equilibria of Lu-Cu-Al system at 870 K is plotted. Compounds Lu 2 (Cu,Al) 17 (the Th 2 Zn 17 type structure), Lu(Cu,Al) 5 (CaCu 5 type structure), Lu 6 (Cu,Al) 23 (Th 6 Mn 23 type structure) and ∼ LuCuAl 2 have been prepared for the first time. Investigation of component interaction in Lu-Cu-Al system shows that the system is similar to previously studied systems Dy-Cu-Al and Er-Cu-Al. The main difference consists in the absence of LuCuAl 3 compound with rhombic structure of the CeNi 2+x Sb 2-x type in the system investigated

Synthesis, Characterization and Comparative Luminescence Studies of Rare-Earth-Doped Gd2O3 Nanoparticles

Science.gov (United States)

Pyngrope, D.; Singh, L. R.; Prasad, A. I.; Bora, A.

2018-04-01

A facile direct precipitation method was used for the synthesis of luminescence nanomaterial. Gd2O3 doped with rare earth element Eu3+ is synthesized by polyol route. The synthesized nanoparticles show their characteristic red emission. The nanoparticles are characterized by x-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and photoluminescence (PL) study. The synthesized nanoparticles are spherical particles with 30 nm size. The photoluminescence studies show the characteristic Eu3+ red emission. The PL study shows the intensity of the magnetic dipole transition ( 5 D0 \\to 7 F1 ) at 592 nm compared to that of the electronic dipole transition ( 5 D0 \\to 7 F2 ) at 615 nm. The nanomaterials can show significant application in various display devices and biomedical applications for tracking.

Rare earth metal alloy magnets

International Nuclear Information System (INIS)

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

1979-01-01

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

Composition and local bonding in RE-Si-M-O-N (M=Mg, Al ; RE=La, Lu) glasses

Energy Technology Data Exchange (ETDEWEB)

Fouquet-Parry, V. [Service de Physique et de Chimie des Surfaces et des Interfaces, DSM/DRECAM/SPCSI, CEA Saclay, 91191 Gif sur Yvette Cedex (France); Paumier, F. [Laboratoire de Metallurgie Physique - UMR 6630 CNRS, Department of Materials Sciences, University of Poitiers (France); Guittet, M.J. [Service de Physique et de Chimie des Surfaces et des Interfaces, DSM/DRECAM/SPCSI, CEA Saclay, 91191 Gif sur Yvette Cedex (France); Gautier-Soyer, M. [Service de Physique et de Chimie des Surfaces et des Interfaces, DSM/DRECAM/SPCSI, CEA Saclay, 91191 Gif sur Yvette Cedex (France)], E-mail: mgautiersoyer@cea.fr; Satet, R.; Hoffmann, M.J. [Institut fuer Keramik im Maschinenbau, Universitaet Karlsruhe (Thailand), Haid-und-Neu-Strasse 7, D 76131 Karlsruhe (Germany); Becher, P.F.; Painter, G.S. [Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States)

2008-05-30

Two series of oxynitride glasses, RE-Si-Mg-O-N (M=Mg, Al ; RE=La, Lu), have been studied by X-Ray photoelectron spectroscopy (XPS). The oxygen 1s photoelectron lineshape reveals a striking difference depending on the rare earth, both in the Mg series and in the Al series. Specifically, the oxygen 1s photoelectron lines of the La doped glasses are broader than the ones of the Lu doped glasses. This result is an experimental evidence that Lu has a larger affinity for oxygen versus nitrogen than La, as theoretically predicted by the first-principles calculations by Painter et al.

Development of Tb{sup 3+} activated gadolinium aluminate garnet (Gd{sub 3}Al{sub 5}O{sub 12}) as highly efficient green-emitting phosphors

Energy Technology Data Exchange (ETDEWEB)

Teng, Xin; Li, Jinkai, E-mail: mse_lijk@ujn.edu.cn; Duan, Guangbin; Liu, Zongming, E-mail: ost_liuzm@ujn.edu.cn

2016-11-15

The powder processing of (Gd{sub 1-x}Tb{sub x}){sub 3}Al{sub 5}O{sub 12} (GdAG:Tb{sup 3+}) solid solutions was achieved through precursor synthesized via carbonate precipitation, followed by calcination at 1500 °C. The performance of the GdAG:Tb{sup 3+} phosphors were characterized by the combined techniques of XRD, FE-SEM, HR-TEM, PLE/PL, and fluorescence decay analyses. Lower Tb{sup 3+} doping can stabilize the crystal structure of GdAG garnet against its thermal decomposition. The GdAG:Tb{sup 3+} phosphors with good dispersion and fairly uniform particle morphology exhibit a series of {sup 5}D{sub 4}–{sup 7}F{sub J} transitions of Tb{sup 3+} with strongest green emission at ~544 nm ({sup 5}D{sub 4}–{sup 7}F{sub 5} transitions of Tb{sup 3+}) under UV excitation at ~277 nm (4f{sup 8}−4f{sup 7}5d{sup 1} transition of Tb{sup 3+}). The later is overlapping with {sup 8}S{sub 7/2}–{sup 6}I{sub J} intra f–f transition of Gd{sup 3+} indirectly suggesting the existence of energy transfer from Gd{sup 3+} to Tb{sup 3+}. With the Gd{sup 3+}–Tb{sup 3+} energy transfer, higher Tb{sup 3+} emission and quantum efficiency than the well-known YAG:Tb{sup 3+} and LuAG:Tb{sup 3+} were obtained in the present work. The effects of Tb{sup 3+} content on luminescent property of the phosphor, especially PLE/PL properties, fluorescence lifetime and quantum efficient, were thoroughly investigated, which were also compared to those of Tb{sup 3+}-activated YAG and LuAG compounds. The CIE chromaticity coordinates and quenching concentration of GdAG:Tb{sup 3+} were determined to be (~0.37, ~0.56) and ~10 at%, respectively. Keeping the optimum Tb{sup 3+} content at ~10 at%, the (Gd{sub 0.9}Tb{sub 0.1})AG phosphor possesses high internal and external quantum efficiencies of ~88.7% and ~73.6% under ~277 nm excitation, respectively. Owing to its improved luminescent property and high theoretical density, the phosphors of (Gd{sub 1-x}Tb{sub x})AG garnet developed in the present work are

Positron annihilation study on the superconductivity of Gd-doped YBCO system

International Nuclear Information System (INIS)

Chen Zhenping; Su Yuling; Xue Yuncai; Liu Haizeng; Gong Shicheng; Zhao Jingxun; Li Xigui

2006-01-01

To make clear the influence of magnetic rare-earth ion Gd 3+ doping in the Y site on crystal structure and localized electron structure of YBCO system, the Gd-doped Y 1-x Gd x Ba 2 Cu 3 O 7-δ (x=0-1.0) systems were studied systematically by the positron annihilation technique and X-ray diffraction (XRD). The XRD analysis reveals that Gd 3+ with bigger radius doping in Y site makes the crystal parameters and crystal volume increase, while all the samples remain the single orthorhombic phase as YBa 2 Cu 3 O 7-δ (YBCO) system does. The temperature dependence of resistance measurement shows that T c is above 90 K for all samples, and T c increases with increasing Gd 3+ content. The positron experiment indicates that the localized electronic density n e decreases with increasing Gd 3+ content. (authors)

Thermoluminescence of double fluorides doped with rare earths

International Nuclear Information System (INIS)

Azorin N, J.; Sanchez R, A.; Khaidukov, N.M.

2004-01-01

In this work the thermoluminescent characteristics of double fluorides K 2 YF 5 , K 2 GdF 5 and K 2 LuF 5 doped are presented with Tb 3+ , studied in the interval of temperature from 30 to 400 C. The materials that presented better answer to the irradiation with particles beta and with ultraviolet light they were the K 2 YF 5 : Tb (1% at. Tb 3+ ) and the K 2 LuF 5 : Tb (1% at. Tb 3+ ); while the K 2 YF 5 : Tb to high concentrations (10% and 20% at. Tb 3+ ) and the K 2 LuF 5 : Tb (1% at. Tb 3+ ) and the K 2 LuF 5 : Tb (1% at. Tb 3+ ) they presented an acceptable answer in front of the gamma radiation. The intensity of the Tl answer induced in these materials is a decisive factor to continue studying its dosimetric characteristics, what allows to consider them as the base for the development of potential materials to use them in the dosimetry of beta particles, of the UV light of the gamma radiation using the thermoluminescence method. (Author)

An improved ion-exchange separation of rare-earth elements for spectrographic analysis

International Nuclear Information System (INIS)

Jones, E.A.

1978-01-01

Rare-earth elements are separated from scandium and base metals by adsorption onto anion resin BIORAD AG1-X8 in the nitrate form from a mixture of 5 per cent 7M nitric acid and 95 per cent methanol. The yttrium subgroup is eluted with a mixture of 45 per cent 7M nitric acid and 55 per cent methanol, followed by elution of the cerium subgroup with 8M nitric acid. This separation facilitates the determination of the traces of the heavier yttrium subgroup of rare-earth elements

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

Science.gov (United States)

Mishra, S N

2009-03-18

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

Whole earth telescope observations of the DBV white dwarf GD 358

Science.gov (United States)

Winget, D. E.; Nather, R. E.; Clemens, J. C.; Provencal, J. L.; Kleinman, S. J.; Bradley, P. A.; Claver, C. F.; Dixson, J. S.; Montgomery, M. H.; Hansen, C. J.

1994-01-01

We report on the analysis of 154 hours of early continuous high-speed photometry on the pulsating DB white dwarf (DBV) GD 358, obtained during the Whole Earth Telescope (WET) run of 1990 May. The power spectrum of the light curve is dominated by power in the range from 1000 to 2400 microHz with more than 180 significant peaks in the total spectrum. We identify all of the triplet frequencies as degree l = 1, and from the details of their spacings we derive the total stellar mass as 0.61 + or - 0.03 solar mass, the mass of the outer helium envelope as 2.0 + or - 1.0 x 10(exp -6) M(sub *), the absolute luminosity as 0.050 + or - 0.012 solar luminosity and the distance as 42 + or - 3 pc. We find strong evidence for differential rotation in the radial direction -- the outer envelope is rotating at least 1.8 times faster than the core -- and we detect the presence of a weak magnetic field with a strength of 1300 + or - 300 G. We also find a significant power at the sums and differences of the dominant frequencies, indicating nonlinear processes are significant, but they have a richness and complexity that rules out resonant mode coupling as a major cause.

Yttrium and lanthanide nitrate complexes of N,N1-bis(4-antipyryl methylidene) ethylenediamine

International Nuclear Information System (INIS)

Joseph, Siby; Radhakrishnan, P.K.

1998-01-01

Complexes of yttrium and lanthanide nitrates with a Schiff base, N, N 1 -bis(4-antipyrylmethylidene)ethylenediamine (BAME) having the general formula [Ln(BAME) 2 (NO 3 )](NO 3 ) 2 , where Ln = Y, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho and Er have been synthesised and characterised by elemental analyses, molar conductance in non-aqueous solvents, electronic, infrared and proton NMR spectra. BAME acts as a neutral bidentate ligand coordinating through both azomethine nitrogen atoms. One of the nitrate groups is coordinated in a bidentate manner. A coordination number of six may be assigned to the metal ion in these complexes. The covalency parameters evaluated from the solid state electronic spectra suggest weak covalent character of the metal-ligand bond. (author)

Interaction of oxygen vacancies in yttrium germanates

KAUST Repository

Wang, Hao

2012-01-01

Forming a good Ge/dielectric interface is important to improve the electron mobility of a Ge metal oxide semiconductor field-effect transistor. A thin yttrium germanate capping layer can improve the properties of the Ge/GeO 2 system. We employ electronic structure calculations to investigate the effect of oxygen vacancies in yttrium-doped GeO 2 and the yttrium germanates Y 2Ge 2O 7 and Y 2GeO 5. The calculated densities of states indicate that dangling bonds from oxygen vacancies introduce in-gap states, but the system remains insulating. However, yttrium-doped GeO 2 becomes metallic under oxygen deficiency. Y-doped GeO 2, Y 2Ge 2O 7 and Y 2GeO 5 are calculated to be oxygen substoichiometric under low Fermi energy conditions. The use of yttrium germanates is proposed as a way to effectively passivate the Ge/dielectric interface. This journal is © 2012 the Owner Societies.

Low temperature specific heat of Lu-Cu-Y metallic glasses

Energy Technology Data Exchange (ETDEWEB)

Mohammed, K.A.; Lanchester, P.C.

1987-02-01

The specific heat of a series of amorphous metallic alloys of the form Lu/sub x/Cu/sub 0.37/Y/sub 0.36/ (x=0, 0.1, 0.3 and 0.4) has been measured between 2 and 50 K, primarily in order to be able to determine the non-magnetic contributions to the specific heat in magnetic Re-Cu-Y amorphous alloys. The data at low temperature fit the simple form C/sub p/=..gamma..T+..beta..T/sup 3/ from which values of ..gamma.. and theta/sub D/(0) have been determined. Consideration is given to the error that arises if Y is used rather than Lu or La in forming non-magnetic rare earth intermetallics for purposes of determining the non-magnetic contributions to the specific heat of magnetic samples. A simple procedure is described that allows a useful improvement in accuracy in estimating non-magnetic contributions below 20 K if Y is used. The method may also be useful if only a restricted range of compositions using Lu is possible.

Indentation recovery in GdPO4 and observation of deformation twinning

Directory of Open Access Journals (Sweden)

Taylor M. Wilkinson

2016-09-01

Full Text Available A series of nanoindentation tests on both single and polycrystalline specimens of a monazite rare-earth orthophosphate, GdPO4, revealed frequent observation of anomalous unloading behavior with a large degree of recovery, where previously this behavior had only been observed in xenotime-structure rare-earth orthophosphates. An indentation site in the polycrystalline sample was examined using TEM to identify the deformation mechanism responsible for recovery. The presence of a twin along the (100 orientation, along with a series of stacking faults contained within the deformation site, provide evidence that the mechanism of recovery in GdPO4 is the collapse of deformation twins during unloading.

Energy transfer mechanism from Gd3+ to Sm3+ in K3Gd(PO4)2:Sm3+ phosphor

International Nuclear Information System (INIS)

Gupta, Palvi; Bedyal, A K; Kumar, Vinay; Khajuria, Y; Sharma, Vishal; Ntwaeaborwa, O M; Swart, H C

2015-01-01

Undoped K 3 Gd(PO 4 ) 2 and trivalent samarium (0.5–2.5 mol%) doped K 3 Gd(PO 4 ) 2 phosphors were synthesized by the solid-state method. The phase formation, optical and luminescence properties were investigated by x-ray diffraction (XRD), diffuse reflectance (DR) spectroscopy, and photoluminescence (PL) spectroscopy. The fluorescence decay spectra of the obtained phosphors were also recorded to study the energy transfer from sensitizer (Gd 3+ ) to activator (Sm 3+ ). Energy transfer effects from sensitizer to activator caused by rare-earth ions were mainly observed in the obtained PL and lifetime spectra. The decay curves of K 3 Gd(PO 4 ) 2 phosphor with different Sm 3+ ions concentrations were found to be non-exponential and the data is well fitted with the Inokuti–Hirayama (I–H) model. The energy transfer parameters such as critical distance for the transfer processes were determined. The Commission Internationale de l’Eclairage (CIE) chromatic coordinates and color-correlated temperature were also determined for the prepared phosphor. (paper)

Effects of rare-earth substitution on the stability and electronic structure of REZnOSb (RE = La-Nd, Sm-Gd) investigated via first-principles calculations

International Nuclear Information System (INIS)

Guo Kai; Man Zhenyong; Cao Qigao; Chen Haohong; Guo Xiangxin; Zhao Jingtai

2011-01-01

Graphical abstract: The structure stability of REZnOSb decreases with varying rare-earth from La to Gd because of the increased binding energy. Research highlights: → As increasing the atomic number of the RE, the structural stability of REZnOSb decreases. → Varying the rare-earth elements from La to Gd, the covalent interactions between [ZnSb] and [LaO] layer are enhanced by 4f-electrons. → The electrical transport properties of REZnOSb could be improved using the large atomic number of the RE. - Abstract: The structural stability, chemical bonding, Mulliken populations, and charge-density distribution of REZnOSb (RE = La-Nd, Sm-Gd) were investigated by first-principles calculations. Unit cell parameters calculated by the generalized gradient approximation (GGA) are in better agreement with experimental results than those derived from the local density approximation (LDA). Binding energy comparisons indicate that the structural stability of REZnOSb decreases with the increment of the atomic number of the RE, as confirmed by X-ray diffraction (XRD) results. Semimetal or narrow band-gap semiconductor behaviors are found for selected REZnOSb. Moreover, chemical bonding analysis shows that there exist considerable polar covalent interactions between the participating atoms. It also reveals that the [ZnSb] layers receive some electrons from the [LaO] layers (donor) as an electrons acceptor and holes transport tunnel. The covalent interactions between the [ZnSb] and [LaO] layers, which are enhanced by 4f-electrons of the RE, are supposed to improve the electrical transport properties.

Evidence for a magnetic moment at the Lu site of LuFe2

International Nuclear Information System (INIS)

Kasamatsu, Y.; Armitage, J.G.M.; Lord, J.S.; Riedi, P.C.; Fort, D.

1995-01-01

High pressure 175 Lu NMR measurements of LuFe 2 at 4.2 K suggest that Lu, like Y and Zr, carries a negative magnetic moment, in agreement with self-consistent energy band calculations. The observed spectrum is more complicated than would be expected for a Laves phase compound. ((orig.))

Rare earth octacyanomolybdates(4)

International Nuclear Information System (INIS)

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

1980-01-01

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

Electronically- and crystal-structure-driven magnetic structures and physical properties of RScSb (R = rare earth) compounds. A neutron diffraction, magnetization and heat capacity study

Energy Technology Data Exchange (ETDEWEB)

Ritter, C [Institut Lauer-Langevin, Grenoble (France); Dhar, S K [TIFR, Mumbai (India); Kulkarni, R [TIFR, Mumbai (India); Provino, A [Inst. SPIN-CNR, Genova (Italy); Univ. of Genova (Italy); Ames Lab., Ames, IA (United States); Paudyal, Durga [Ames Lab., Ames, IA (United States); Manfrinetti, Pietro [Inst. SPIN-CNR, Genova (Italy); Univ. of Genova (Italy); Ames Lab., Ames, IA (United States); Gschneidner, Karl A [Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States)

2014-08-14

The synthesis of the new equiatomic RScSb ( R = La-Nd, Sm, Gd-Tm, Lu, Y) compounds has been recently reported. These rare earth compounds crystallize in two different crystal structures, adopting the CeScSi-type ( I 4/ mmm) for the lighter R (La-Nd, Sm) and the CeFeSi-type (P4 /nmm) structure for the heavier R ( R = Gd-Tm, Lu, Y). Here we report the results of neutron diffraction, magnetization and heat capacity measurements on some of these compounds ( R = Ce, Pr, Nd, Gd and Tb). Band structure calculations have also been performed on CeScSb and GdScGe (CeScSi-type), and on GdScSb and TbScSb (CeFeSi-type) to compare and understand the exchange interactions in CeScSi and CeFeSi structure types. The neutron diffraction investigation shows that all five compounds order magnetically, with the highest transition temperature of 66 K in TbScSb and the lowest of about 9 K in CeScSb. The magnetic ground state is simple ferromagnetic (τ = [0 0 0]) in CeScSb, as well in NdScSb for 32 >T > 22 K. Below 22 K a second magnetic transition, with propagation vector τ = [¼ ¼ 0], appears in NdScSb. PrScSb has a magnetic structure within, determined by mostly ferromagnetic interactions and antiferromagnetic alignment of the Pr-sites connected through the I-centering ( τ = [1 0 0]). A cycloidal spiral structure with a temperature dependent propagation vector τ = [δ δ ½] is found in TbScSb. The results of magnetization and heat capacity lend support to the main conclusions derived from neutron diffraction. As inferred from a sharp peak in magnetization, GdScSb orders antiferromagnetically at 56 K. First principles calculations show lateral shift of spin split bands towards lower energy from the Fermi level as the CeScSi-type structure changes to the CeFeSi-type structure. This rigid shift may force the system to transform from exchange split ferromagnetic state to the antiferromagnetic state in RScSb compounds (as seen for example in GdScSb and TbScSb) and is proposed to

Weak ferromagnetism in Re0.67Ca0.33FeO3 (Re=La, Sm, Gd) nanoparticles

International Nuclear Information System (INIS)

Li Jiangong; Kou Xinli; Qin Yong; He Haiying

2003-01-01

Perovskite-type complex ferrite Re 0.67 Ca 0.33 FeO 3 (Re=La, Sm, Gd) nanoparticles of nearly the same particle size were prepared using sol-gel method. The influence of rare-earth ions on weak ferromagnetism in the Re 0.67 Ca 0.33 FeO 3 nanoparticles has been studied. The spontaneous magnetization M s of the Sm 0.67 Ca 0.33 FeO 3 nanoparticles is greater than that of Gd 0.67 Ca 0.33 FeO 3 nanoparticles; and M s of Gd 0.67 Ca 0.33 FeO 3 nanoparticles is greater than that of La 0.67 Ca 0.33 FeO 3 nanoparticles. The ferromagnetic component arising from the Fe sublattice increases with the decreasing rare-earth ionic radii. The magnetization of the rare-earth ions in the Sm 0.67 Ca 0.33 FeO 3 nanoparticles is smaller than that in the Gd 0.67 Ca 0.33 FeO 3 nanoparticles. The influences of the geometric and intrinsic magnetic characters of rare-earth ions as well as the particle size of the nanoparticles on weak ferromagnetism are discussed

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

International Nuclear Information System (INIS)

Majeed, Abdul; Khan, Muhammad Azhar; Raheem, Faseeh ur; Hussain, Altaf; Iqbal, F.; Murtaza, Ghulam; Akhtar, Majid Niaz; Shakir, Imran; Warsi, Muhammad Farooq

2016-01-01

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

Scandium, yttrium and the lanthanides

International Nuclear Information System (INIS)

Hart, F.A.

1987-01-01

This chapter on the chemistry of the coordination complexes of scandium, yttrium and the lanthanides includes sections on the nitrogen and oxygen donor ligands and complex halides of scandium, and the phosphorus and sulfur donor ligands of yttrium and the lanthanides. Complexes with the macrocylic ligands and with halides are also discussed. Sections on the NMR and electronic spectra of the lanthanides are also included. (UK)

Theory of Rare-Earth Alloys

DEFF Research Database (Denmark)

Lindgård, Per-Anker

1977-01-01

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

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

International Nuclear Information System (INIS)

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

1991-01-01

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

Features of solid solutions composition in magnesium with yttrium alloys

International Nuclear Information System (INIS)

Drits, M.E.; Rokhlin, L.L.; Tarytina, I.E.

1983-01-01

Additional data on features of yttrium solid solutions composition in magnesium in the course of their decomposition investigation in the case of aging are obtianed. The investigation has been carried out on the base of a binary magnesium-yttrium alloy the composition of which has been close to maximum solubility (at eutectic temperature) and magnesium-yttrium alloys additionally doped with zinc. It is shown that higher yttrium solubility in solid magnesium than it has been expected, issueing from the difference in atomic radii of these metals indicates electron yttrium-magnesium atoms interaction. In oversaturated magnesium-yttrium solid solutions at earlier decomposition stages Mg 3 Cd type ordering is observed. At aging temperatures up to 250 deg C and long exposures corresponding to highest strengthening in oversaturated magnesium yttrium solid solutions a rhombic crystal lattice phase with three symmetric orientations is formed

Extraction of nitrates of lanthanoids (3) of the yttrium group and yttrium (3) by trialkylbenzylammonium nitrate in toluene

International Nuclear Information System (INIS)

Pyartman, A.K.; Kovalev, S.V.; Keskinov, V.A.; Kopyrin, A.A.

1997-01-01

A study was made on extraction of nitrates of lanthanoids (3) of the yttrium group (terbium-lutetium) and yttrium (3) by trialkylbensylammonium nitrate in toluene at T=298.15 K pH 2. Extraction isotherms are described with account of formation of compound of (R 4 N) 2 [Ln(NO 3 ) 5 ] composition in organic phase. Values of extraction constants decreasing in terbium (3)-lutetium (3) series, were calculated. Value of extraction constant for yttrium (3) is close to the value of extraction constant for ytterbium (3). 13 refs., 2 figs., 3 tabs

High purity neodymium acetate from mixed rare earth carbonates

International Nuclear Information System (INIS)

Queiroz, Carlos A. da Silva; Rocha, Soraya M. Rizzo da; Vasconcellos, Mari E. de; Lobo, Raquel M.; Seneda, Jose A.; Pedreira, Walter dos R.

2011-01-01

A simple and economical chemical process for obtaining high purity neodymium acetate is discussed. The raw material in the form rare earth carbonate is produced industrially from the chemical treatment of Brazilian monazite. Ion exchange chromatography technique with a strong cationic resin, proper to water treatment, and without the use of retention ions was used for the fractionating of the rare earth elements (REE). In this way, it was possible to obtain 99.9% pure Nd 2 O 3 in yields greater than or equal 80%, with the elution of the REE using ammonium salt of ethylenediaminetetraacetic acid (EDTA) solution in pH controlled. The complex of EDTA-neodymium was transformed into neodymium oxide, which was subsequently dissolved in acetic acid to obtain the neodymium acetates. Molecular absorption spectrophotometry was used to monitor the neodymium content during the process and sector field inductively coupled plasma mass spectrometry was used to certify the purity of the neodymium acetates. The typical neodymium acetates obtained contain the followings contaminants in μg g -1 : Sc(5.1); Y (0.9); La (1.0); Ce (6.1); Pr (34,4); Sm (12.8); Eu (1.1); Gd (15.4); Tb (29.3); Dy (5.2), Ho(7.4); Er (14.6); Tm (0.3); Yb (2.5); Lu (1.0). The high purity neodymium acetates obtained from this procedure have been applied, replacing the imported product, in research and development area on rare earth catalysts. (author)

The low temperature specific heat of Lu-Cu-Y metallic glasses

International Nuclear Information System (INIS)

Mohammed, K.A.; Lanchester, P.C.

1987-01-01

The specific heat of a series of amorphous metallic alloys of the form Lu x Cu 0.37 Y 0.36 (x=0, 0.1, 0.3 and 0.4) has been measured between 2 and 50 K, primarily in order to be able to determine the non-magnetic contributions to the specific heat in magnetic Re-Cu-Y amorphous alloys. The data at low temperature fit the simple form C p =γT+βT 3 from which values of γ and θ D (0) have been determined. Consideration is given to the error that arises if Y is used rather than Lu or La in forming non-magnetic rare earth intermetallics for purposes of determining the non-magnetic contributions to the specific heat of magnetic samples. A simple procedure is described that allows a useful improvement in accuracy in estimating non-magnetic contributions below 20 K if Y is used. The method may also be useful if only a restricted range of compositions using Lu is possible. (orig.)

Effects of rare earth elements on growth and metabolism of medicinal plants

Directory of Open Access Journals (Sweden)

Chunhong Zhang

2013-02-01

Full Text Available The rare earth elements (REEs are a set of 17 chemical elements. They include the lanthanide series from lanthanum (La to lutetium (Lu, scandium (Sc, and yttrium (Y in the periodic table. Although REEs are used widely in industry and agriculture in China for a long time, there has been increasing interest in application of REEs to medicinal plants in recent years. In this paper, we summarize researches in the past few decades regarding the effects of REEs on the germination of seeds, the growth of roots, total biomass, and the production of its secondary metabolites, as well as their effects on the absorption of minerals and metals by medicinal plants. By compilation and analysis of these data, we found that REEs have promoting effects at low concentrations and negative effects at comparatively high concentrations. However, most studies focused only on a few REEs, i.e., La, cerium (Ce, neodymium (Nd and europium (Eu, and they made main emphasis on their effects on regulation of secondary metabolism in tissue-cultured plants, rather than cultivated medicinal plants. Advanced research should be invested regarding on the effects of REEs on yields of cultivated plants, specifically medicinal plants.

Uranium, yttrium, and rare earth elements accumulation during the Cretaceous anoxic events in carbonaceous rocks in the Pacific Ocean

Science.gov (United States)

Savelyeva, Olga; Philosofova, Tatyana; Bergal-Kuvikas, Olga; Savelyeva, Svetlana

2017-04-01

We have studied the carbonate-siliceous section of paleooceanic Albian-Cenomanian deposits on the Kamchatsky Mys peninsula (Eastern Kamchatka, Russia) [1].The section is represented by a rhythmic alternation of planktonic limestones and jaspers, accumulated in the open ocean environment. The rhythmicity can be attributed to climate variations that reflect a fluctuation of astronomical parameters (Milankovitch cycles) [2, 3].The section contains two beds enriched in organic carbon, corresponding to the two oceanic anoxic events - MCE and OAE2 [3]. The maximum content of organic matter in those beds reaches 68%. Our geochemical studies revealed an enrichment of the carbonaceous rocks in some major and trace elements including PGE, in comparison with the surrounding limestone and jasper [4].The accumulation of the ore elements in carbonaceous beds is caused by euxinic conditions during sedimentation.The content of uranium, yttrium, and rare earth elements in carbonaceous rocks is up to 60, 142 and 312 ppm respectively. Phosphate grains (bone detritus) with microinclusions of yttrium and uranium minerals were revealed in the carbonaceous rocks using the scanning electron microscope. These data prove the hypothesis of the sorbtion of U and Y by phosphate detritus from seawater. Microprobe analysis also showed an increased content of Cu, Zn, V in some pyrite framboids, which indicates that these elements are fixed in rocks by Fe-sulphide phase or organic matter under euxinic conditions. Our research may bring us closer to understanding the mechanism of syngenetic accumulation of metals in the black shales. This work was supported by the RFBR (No. 16-05-00546). [1] Palechek, T.N., Savelyev, D.P., Savelyeva, O.L. (2010) Stratigraphy and Geological Correlation 18, (1) 63-82. [2] Savelyeva, O.L. (2010). Vestnik Kraunts. Nauki o zemle 1 (15), 45-55 (in Russian). [3] Savelyev, D.P., Savelyeva, O.L., Palechek, T.N., Pokrovsky, B.G. (2012) Geophysical Research Abstracts, 14, EGU

Yttrium synovectomy: a meta-analysis of the literature

International Nuclear Information System (INIS)

Jones, G.

1993-01-01

Yttrium synovectomy for chronic synovitis of the knee enjoys widespread usage in Australia with approximately 400 patients receiving yttrium-90 in 1991. Despite abundant anecdotal evidence of its efficacy there is a paucity of controlled trials and those that have been done have produced conflicting results and have been of insufficient sample size. To critically and quantitatively evaluate the published English literature on comparative trials of yttrium-90 therapy for chronic synovitis of the knee, the technique of meta-analysis was utilised. The literature search was carried out using the MeSH terms of synovectomy and knee; and yttrium. This was augmented by referring to reviews, current textbooks and back-references. Outcome measures varied between trials but could be grouped as treatment success. The Peto modification of Mantel and Haenszl was used for statistical pooling of data yielding a pooled odds ratio (OR). The literature search revealed ten controlled trials of which two were excluded from further analysis. It was found that yttrium was superior to placebo (OR 2.42, 95% CI 1.02-5.73) but it is recommended that this result should be interpreted with caution due to possible publication bias. It is concluded that there is insufficient evidence from comparative trials of yttrium in the English literature to show that yttrium synovectomy is convincingly superior to triamcinolone (OR 1.89, 95% CI 0.81-10.55) or other active modalities (OR 1.04, 95% CI 0.72-1.52). 25 refs., 4 tabs

On the use of hydrogen peroxide as a masking agent for the determination of yttrium in uranium oxide - yttrium oxide mixture

International Nuclear Information System (INIS)

Rastogi, R.K.; Chaudhuri, N.K.; Rizvi, G.H.; Subramanian, M.S.

1985-01-01

The use of peroxide as a masking agent for uranium during the EDTA titration of yttrium in an yttrium-uranium mixture containing large amounts of uranium was investigated. High acetate ion concentration was necessary to keep the peroxy complex of uranium in solution during the titration. It was observed that uranium could be tolerated up to 500 mg in the determination of yttrium with 0.5 ml of 30% hydrogen peroxide in approx. 1M acetate medium. The precision and accuracy of the method based on 16 determinations of yttrium at 6-16 mg level in the presence of 300 mg uranium was found to be +-0.2%. (author)

Investigation of local magnetism in RZn (R = Ce, Gd, Tb, Dy) and GdCu intermetallic compounds using perturbed angular correlation gamma-gamma spectroscopy; Investigacao do magnetismo local em compostos intermetalicos do tipo RZn (R = Ce, Gd, Tb, Dy) e GdCu pela espectroscopia de correlacao angular gama-gama perturbada

Energy Technology Data Exchange (ETDEWEB)

Santos, Brianna Bosch dos

2010-07-01

This work presents, from a microscopic point of view, a systematic study of the local magnetism in RZn (R = Ce, Gd, Tb, Dy) and GdCu intermetallic compounds through measurements of hyperfine interactions using the Perturbed Angular Correlation Gamma- Gamma Spectroscopy technique with {sup 111}In {yields} {sup 111}Cd and {sup 140}La {yields} {sup 140}Ce as probe nuclei. As the magnetism in these compounds originates from the 4f electrons of the rare-earth elements it is interesting to observe in a systematic study of RZn compounds the behavior of the magnetic hyperfine field with the variation of the number of 4f electrons in the R element. The use of probe nuclei {sup 140}La {yields} {sup 140}Ce is interesting because Ce{sup +3} ion posses one 4f electron which may contribute to the total hyperfine field, and the results showed anomalous behavior. The results for {sup 111}Cd probe showed that the temperature dependence of the magnetic hyperfine field follows the Brillouin function, and the magnetic hyperfine field decreases linearly with increase of the atomic number of rare earth when plotted as a function of the rare-earth J spin projection, showing that the main contribution to the magnetic hyperfine field in RZn compounds comes from the polarization of the conduction electrons. The results for the electric field gradient measured with {sup 111}Cd for all compounds showed a strong decrease with the atomic number of the rare-earth element. We have therefore assumed that the major contribution to the electric field gradient originates from the 4f electrons of the rare-earths. The measurements of the electric field gradient for GdCu with {sup 111}Cd, after temperature decreases and increases again showed that two different structures, CsCl-type cubic and FeB-type orthorhombic structures co-exist. Finally, it is the first time that measurements of hyperfine parameters have been carried out with theses two probe nuclei in the studied RZn. (author)

Graphite furnace atomic absorption spectrometry with a tantalum boat for the determination of yttrium, samarium, and dysprosium in a mish metal

International Nuclear Information System (INIS)

Daidoji, Hidehiro; Tamura, Shohei

1982-01-01

The determination of yttrium, samarium, and dysprodium by means of graphite-furnace atomic absorption spectrometry (AAS) was studied by a tantalum boat inserted into a graphite tube atomizer. These elements could not be determined by the use of a commercial graphite tube, In the atomization from a tantalum boat, better analytical sensitivities and negligible memory effects for these rare earths are obtained. The analytical sensitivities of yttrium, samarium, and dysprodium with the tantalum boat were 0.60 ng, 0.86 ng, and 0.17 ng respectively. This method was applied for the determination of yttrium, samarium, and dysprosium in a mish metal. The measurements were performed with slightly acidified solutions (0.01 mol dm 3 HCI or HNO 3 ). The sensitivities and the precisions for these elements decreased with increasing acid concentration. An enhancement in the sensitivities of yttrium and dysprosium upon the addition of a large excess of lanthanum, neodymium, and praseodymium salts were observed. The yttrium, samarium, and dysprosium in a mish metal were determined with both analytical curves of standard solutions containing an excess of lanthanum, cerium, and neodymium ions and of the standard addition. The precisions for this work were in the 3 - 9.3% range. (author)

Standardization of Procedures for the Preparation of (177)Lu- and (90)Y-labeled DOTA-Rituximab Based on the Freeze-dried Kit Formulation.

Science.gov (United States)

Wojdowska, Wioletta; Karczmarczyk, Urszula; Maurin, Michal; Garnuszek, Piotr; Mikołajczak, Renata

2015-01-01

Rituximab when radiolabelled with (177)Lu or (90)Y has been investigated for the treatment of patients with Non-Hodgkin's Lymphoma. In this study, we optimized the preparation of antibody conjugates with chelating agent in the freeze-dried kit. It shortens procedures needed for the successful radiolabeling with lutetium-177 and yttrium-90 and assures reproducible labelling yields. Various molar ratios of Rituximab:DOTA (from 1:5 to 1:100) were used at the conjugation step and different purification method to remove unbound DOTA were investigated (size-exclusion chromatography, dialysis, ultrafiltration). The final monoclonal antibody concentration was quantified by Bradford method, and the number of DOTA molecules was determined by radiolabeling assay using (64)Cu. The specific activity of (177)Lu-DOTA-Rituximab and (90)Y-DOTA-Rituximab were optimized using various amounts of radiometal. Quality control (SE-HPLC, ITLC) and stability study were performed. An average of 4.2 ± 0.8 p-SCN-Bz-DOTA molecules could be randomly conjugated to a single molecule of Rituximab. The ultrafiltration system was the most efficient for purification and resulted in the highest recovery efficiency (77.2%). At optimized conditions the (177)Lu-DOTARituximab and (90)Y-DOTA-Rituximab were obtained with radiochemical purity >99% and specific activity ca. 600 MBq/mg. The radioimmunoconjugates were stable in human serum and 0.9% NaCl. After 72 h of incubation the radiochemical purity of (177)Lu-DOTA-Rituximab decreased to 94% but it was still more than 88% for (90)Y-DOTA-Rituximab. The radioimmunoconjugate showed stability after six months storage at 2 - 8(0)C, as a lyophilized formulation. Our study shows that Rituximab-DOTA can be efficiently radiolabeled with (177)Lu and (90)Y via p-SCN-Bn-DOTA using a freezedried kit.

Large magnetocaloric effect of GdNiAl2 compound

International Nuclear Information System (INIS)

Dembele, S.N.; Ma, Z.; Shang, Y.F.; Fu, H.; Balfour, E.A.; Hadimani, R.L.; Jiles, D.C.; Teng, B.H.; Luo, Y.

2015-01-01

This paper presents the structure, magnetic properties, and magnetocaloric effect of the polycrystalline compound GdNiAl 2 . Powder X-ray diffraction (XRD) measurement and Rietveld refinement revealed that GdNiAl 2 alloy is CuMgAl 2 -type phase structure with about 1 wt% GdNi 2 Al 3 secondary phase. Magnetic measurements suggest that the compound is ferromagnetic and undergoes a second-order phase transition near 28 K. The maximum value of magnetic entropy change reaches 16.0 J/kg K for an applied magnetic field change of 0–50 kOe and the relative cooling power was 6.4×10 2 J/kg. It is a promising candidate as a magnetocaloric material working near liquid hydrogen temperature (~20 K) exhibiting large relative cooling power. - Highlights: • Preferred orientation with axis of [010] was found in the GdNiAl 2 compound. • The ΔS Mmax and the RCP are 16.0 J/kg K and 640 J/kg, respectively, for ΔH=50 kOe. • Relative low rare earth content in GdNiAl 2 comparing with other candidates

Studies on the pressed yttrium oxide-tungsten matrix as a possible dispenser cathode material

International Nuclear Information System (INIS)

Yang, Fan; Wang, Jinshu; Liu, Wei; Liu, Xiang; Zhou, Meiling

2015-01-01

Yttrium oxide was chosen as the secondary emission substance based on calculation results through first principle theory method. A new kind of pressed yttrium oxide-tungsten matrix dispenser cathodes are prepared by a sol–gel method combined with high temperature sintering in dry hydrogen atmosphere. The results show that the growth of the grains is hampered by the pinning effect of Y 2 O 3 distributing uniformly between the tungsten particles, resulting in the formation of small grain size. It is found that Y 2 O 3 improves the secondary electron emission property, i.e., the secondary emission yield increases with the increase of Y 2 O 3 content in the samples. The maximum secondary emission yield δ max of the cathode with 15% amount of Y 2 O 3 can reach 2.92. Furthermore, the cathode shows a certain thermionic emission performance. The zero field emission current density J 0 of 4.18A/cm 2 has reached at 1050 °C b for this kind of cathode after being activated at 1200 °C b , which are much higher than that of rare earth oxide doped molybdenum (REO-Mo) cathode reported in the previous work. - Highlights: • Yttrium oxide was chosen as the secondary emission substance based on first principle calculation result. • A new kind of cathode has been successfully obtained. • Pressed yttrium oxide-tungsten matrix dispenser cathode exhibits good emission properties. • The improvement of the cathode emission can be well explained by the surface analysis results presented in this work

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

Energy Technology Data Exchange (ETDEWEB)

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

2012-05-15

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

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

International Nuclear Information System (INIS)

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

2012-01-01

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

ICP-MS determination of rare earth elements, yttrium, uranium and thorium in niobium-tantalum rich samples

International Nuclear Information System (INIS)

Sunilkumar, Beena; Padmasubashini, V.

2013-01-01

ICP-MS is a powerful and extremely sensitive technique which has been applied successfully for the determination of REEs in diverse geological samples. In the present work, ICP-MS has been applied for the rapid determination of REEs, yttrium as well as uranium and thorium in niobium and tantalum rich samples, using a fluoride fusion method for sample dissolution

Mixed ligand lanthanide complexes with dipivaloylmethane and acetic acid

International Nuclear Information System (INIS)

Lyu Fehnkhua; Kuz'mina, N.P.; Mazo, G.N.; Martynenko, L.I.

1995-01-01

Methods of elemental, X-ray phase, thermal analyses and infrared spectroscopy were used to characterize solid products, formed in MDpm 3 -HAcet-H-hexane systems (M = Pr, Nd, Eu, Gd, Ho, Er, Yb, HDpm -dipivaloylmethane, HAcet - acetic acid). It was established that prepared mixed ligand complexes (MLC) had MDpm 2 Acet composition for all studied rare earths. Differenced in properties of cerium and yttrium rare earths are manifested in processes of MLC thermal dissociation, proceeding at low pressure and 170 deg C. 6 refs., 4 tabs

Activation analysis of rare-earth elements in opium and cannabis samples. [Neutron reactions

Energy Technology Data Exchange (ETDEWEB)

Henke, G [Muenster Univ. (Germany, F.R.). Inst. fuer Pharmazeutische Chemie

1977-01-01

Rare-earth concentrations in 65 Opium, Cannabis and Cannabis resin samples seized from various parts of the world were determined by destructive NAA. Because of the greater concentrations of Ca, P, K, Fe, Na and Si in plant materials, rare-earth elements were isolated after neutron irradiation and determined by gamma-spectrometry. The main steps of the method are: Preashing of 1 g Cannabis resin, 2.5 g Cannabis, or 7.5 g Opium, respectively, in quartz ampoules (5 h, 500 deg C). Neutron irradiation, 24 h at 5x10/sup 13/n cm/sup -2/sec/sup -1/. Cooling period 2-3 days. After addition of 0.1 ..mu..Ci /sup 139/Ce and rare-earth carriers wet ashing of irradiated samples with H/sub 2/SO/sub 4//HNO/sub 3/, followed by alternate addition of HNO/sub 3/ and H/sub 2/O/sub 2/ (30%). Precipitation and removal of silicates, precipitation of fluorides, precipitation of hydroxides. Dissolution of hydroxides in HCl. Extraction with di-(2-ethylhexyl)phosphate (DEHP)/toluene and twice back-extraction of rare earths, gamma-spectrometry of HCl phase. Due to sample activity and half-life of nuclides, three measurements were made on each sample: 2 days (for La, Sm, Gd, Ho, Er, Yb); 14 days (for Nd, Lu) and 30 days after irradiation (for Ce, Eu, Tb). Great variations in absolute element concentrations, but only small significant differences of rare earth concentration ratios were found, indicating inconsiderable biogeochemical fractionation. The mean values of these ratios correspond to the relative abundances of the rare earths in the upper continental earth's crust.

Advancing Control for Shield Tunneling Machine by Backstepping Design with LuGre Friction Model

Directory of Open Access Journals (Sweden)

Haibo Xie

2014-01-01

Full Text Available Shield tunneling machine is widely applied for underground tunnel construction. The shield machine is a complex machine with large momentum and ultralow advancing speed. The working condition underground is rather complicated and unpredictable, and brings big trouble in controlling the advancing speed. This paper focused on the advancing motion control on desired tunnel axis. A three-state dynamic model was established with considering unknown front face earth pressure force and unknown friction force. LuGre friction model was introduced to describe the friction force. Backstepping design was then proposed to make tracking error converge to zero. To have a comparison study, controller without LuGre model was designed. Tracking simulations of speed regulations and simulations when front face earth pressure changed were carried out to show the transient performances of the proposed controller. The results indicated that the controller had good tracking performance even under changing geological conditions. Experiments of speed regulations were carried out to have validations of the controllers.

Chemical bonding and magnetic properties of gadolinium (Gd) substituted cobalt ferrite

International Nuclear Information System (INIS)

Puli, Venkata Sreenivas; Adireddy, Shiva; Ramana, C.V.

2015-01-01

Graphical abstract: Room temperature Raman spectra of CoFe 2−x Gd x O 4 (CFGO, x = 0.0–0.3) compounds as a function of wavenumber (cm −1 ). - Highlights: • Gd substituted ferrites were synthesized under controlled concentration. • Gd ion induced lattice dynamical changes are significant. • Enhanced magnetization is observed upon Gd-incorporation in cobalt ferrite. • A correlation between lattice dynamics and magnetic properties is established. - Abstract: Polycrystalline gadolinium (Gd) substituted cobalt ferrites (CoFe 2−x Gd x O 4 ; x = 0–0.3, referred to CFGO) ceramics have been synthesized by solid state reaction method. Chemical bonding, crystal structure and magnetic properties of CFGO compounds have been evaluated as a function of Gd-content. X-ray diffraction (XRD) and Raman spectroscopic analyses confirmed the formation of inverse spinel cubic structure. However, a secondary ortho-ferrite phase (GdFeO 3 ) nucleates for higher values of Gd-content. A considerable increase in the saturation magnetization has been observed upon the initial substitution of Gd (x = 0.1). The saturation magnetization drastically decreases at higher Gd content (x ⩾ 0.3). No contribution from ortho-ferrite GdFeO 3 phase is noted to the magnetic properties. The increase in the magnetic saturation magnetization is attributed to the higher magnetic moment of Gd 3+ (4f 7 ) residing in octahedral sites is higher when compared to that of Fe 3+ (3d 5 ) and as well due to the migration of Co 2+ (3d 7 ) ions from the octahedral to the tetrahedral sites with a magnetic moment aligned anti-parallel to those of rare earth (RE 3+ ) ions in the spinel lattice. Increase in coercivity with increase in Gd 3+ is content is attributed to magnetic anisotropy in the ceramics

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-06-15

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

Study of the production of 177Lu through 176Yb (n, γ) 177Yb → 177Lu nuclear reaction

International Nuclear Information System (INIS)

Silva, Giovana Pasqualini da; Osso Junior, Joao Alberto

2007-01-01

The beta minus emitter 177 Lu is a promising therapeutic radioisotope for the curative treatment of cancer using labelled proteins. It has a half - life of T 1/2 = 6.71 day and maximum and average β - energies of 421 and 133 keV, resulting in a short range of radiation in tissue. The decay is accompanied by the emission of low energy γ-radiation with 208.3 keV (11%) and 113 keV (6.4%) suitable for simultaneous imaging, 177 Lu can be produced by two different routes, namely, by irradiation of natural Lu 2 O 3 target ( 176 Lu, 2.6%) or enriched (in 176 Lu) Lu 2 O 3 target, as also by irradiation of Yb target (Yb 2 O 3 ) followed by radiochemical separation of 177 Lu from Yb isotopes. The objective of this work is to study the production of 177 Lu through the indirect 176 Yb(n,γ) 177 Yb → 177 Lu nuclear reaction. The results of the production yield of 177 Lu will be shown and compared with the direct reaction. The method of choice for the chemical separation between Lu and Yb was the ion exchange, using an cation exchange resin in Cl - form and α-HIBA as eluent. Preliminary results showed a good separation of 177 Lu from Yb 2 O 3 indirect targets. (author)

High purity samarium oxide from mixed rare earth carbonates

International Nuclear Information System (INIS)

Queiroz, Carlos A. da S.; Seneda, Jose A.; Vasconcellos, Mari E. de; Pedreira Filho, Walter dos R.

2013-01-01

A simple and economical chemical process for the production of highly pure samarium oxides is discussed. The raw material, which was used in the form of rare earth carbonates was produced industrially from the chemical treatment of Brazilian monazite. Ion exchange chromatography was performed using a strong cationic resin that is typically employed in water treatment processes to fractionate rare earth elements (REE) without the use of retention ions. Under these conditions, 99.9% pure Sm 2 O 3 was eluted using the ammonium salt of ethylenediaminetetraacetic acid (EDTA) at a controlled pH. The EDTA-samarium complex was separated from EDTA and then precipitated as oxalate and fired to samarium oxide. Molecular absorption spectrophotometry was used to monitor the samarium content during the proposed process, and sector field inductively coupled plasma mass spectrometry was used to certify the purity of the samarium oxide. Typical samarium oxide obtained from the proposed procedure contained the following contaminants in micrograms per gram: Sc (20.90); Y (11.80); La (8.4); Ce (4.3); Pr (2.5); Nd (5.1); Eu (94); Gd (114); Tb (3.6); Dy (2.5), Ho (2.3); Er (3.0); Tm (2.3); Yb (38,2); Lu (25.6). The high-purity samarium oxides produced in the present study can be used as an alternative to imported products in research and development applications. (author)

Memories of Lu Jingqing

Institute of Scientific and Technical Information of China (English)

1994-01-01

Lu Jingqing was a woman of letters who wrote poems when she was young and also worked as an editor and teacher. Her main works are Women poets of the Tang Dynasty (1931), Whisper (a collection of poems, 1932), Plain Writing (a collection of verses, 1930) and The Wandering (1933). In March 1993, 86-year-old Lu Jingqing, Professor of the Shanghai College of Finance and Economics, died in Shanghai. Zhu Bokang, an old friend of Lu and her husband wrote the following article in her memory.

Magnetic Interaction between Surface-Engineered Rare-Earth Atomic Spins

Directory of Open Access Journals (Sweden)

Chiung-Yuan Lin

2012-06-01

Full Text Available We report the ab-initio study of rare-earth adatoms (Gd on an insulating surface. This surface is of interest because of previous studies by scanning tunneling microscopy showing spin excitations of transition-metal adatoms. The present work is the first study of rare-earth spin-coupled adatoms, as well as the geometry effect of spin coupling and the underlying mechanism of ferromagnetic coupling. The exchange coupling between Gd atoms on the surface is calculated to be antiferromagnetic in a linear geometry and ferromagnetic in a diagonal geometry. We also find that the Gd dimers in these two geometries are similar to the nearest-neighbor and the next-nearest-neighbor Gd atoms in GdN bulk. We analyze how much direct exchange, superexchange, and Ruderman-Kittel-Kasuya-Yosida interactions contribute to the exchange coupling for both geometries by additional first-principles calculations of related model systems.

Neutron diffraction studies on GdB6 and TbB6 powders

International Nuclear Information System (INIS)

Luca, S.E.; Amara, M.; Galera, R.M.; Givord, F.; Granovsky, S.; Isnard, O.; Beneu, B.

2004-01-01

We report here the first powder neutron diffraction study of GdB 6 and TbB 6 . GdB 6 and TbB 6 order antiferromagnetically at 15 and 21 K, respectively. In both compounds the transition at T N is of the first order. Moreover GdB 6 presents a second spontaneous magnetic transition at T * =8 K. The present study shows that, in both compounds, the magnetic propagation vectors belong to the star and that the direction of the magnetic moment is perpendicular to the ((1)/(2)) component of the wave-vector in GdB 6 , while in TbB 6 the moment is parallel to it. The deduced low-temperature values of the magnetic moments agree with those of the respective rare-earth trivalent ions

Surface modifications induced by yttrium implantation on low manganese-carbon steel

Energy Technology Data Exchange (ETDEWEB)

Caudron, E.; Buscail, H. [Univ. Blaise Pascal Clermont-Fd II, Le Puy en Velay (France). Lab. Vellave d' Elaboration et d' Etude des Materiaux; Haanapel, V.A.C.; Jacob, Y.P.; Stroosnijder, M.F. [Institute for Health and Consumer Protection, Joint Research Center, The European Commission, 21020, Ispra (Italy)

1999-12-15

Low manganese-carbon steel samples were ion implanted with yttrium. Sample compositions and structures were investigated before and after yttrium implantations to determine the yttrium distribution in the sample. Yttrium implantation effects were characterized using several analytical and structural techniques such as X-ray photoelectron spectroscopy, reflection high energy electron diffraction, X-ray diffraction, glancing angle X-ray diffraction and Rutherford backscattering spectrometry. In this paper it is shown that correlation between composition and structural analyses provides an understanding of the main compounds induced by yttrium implantation in low manganese-carbon steel. (orig.)

Determination of rare earth elements in water ore and grass sample around monazite dressing plant by high performance liquid chromatography

International Nuclear Information System (INIS)

Laoharojanaphand, S.

1993-01-01

High performance liquid chromatography technique for the analysis of rare earth elements; yttrium, cerium and lanthanum, was developed. A comparison of two mobile phases between α-hydroxy isobutyric acid and mandelic acid was carried out using C 1 8 column for separation and the amount of the rare earth elements were detected by post column complex formation with Arsenazo III. It was found that α-hydroxy isobutyric acid had higher efficiency in separation of the rare earth elements than mandelic acid when 1-octanesulfonic acid was used as an organic modifier. The optimum conditions of the mobile phase were comprised of the p H of 3.65, a flow rate of 1 ml/min which resulted in the values of resolution to be 13.62 between yttrium and cerium and 3.49 between cerium and lanthanum. Standard curves of yttrium and lanthanum yielded linear range of 0.1-45 and 1-60 ppm whereas the cerium curve was in the range of 1-100 ppm. The analyses of water, ore and grass samples collected around the monazite dressing plants from Prachuap Khiri Khan and Phuket showed that none of the rare earth elements was detected in all samples from Prachuap Khiri Khan. But 0.5 ppm of yttrium and 1.5 ppm of lanthanum were found in the water samples from Phuket while in the grass samples contained yttrium and cerium in the amounts of 2 ppm and 14 ppm whereas none was detected in the ore samples by this technique under the previous conditions

Chromates (3) and chromates (5) of rare earths

International Nuclear Information System (INIS)

Suponitskij, Yu.L.

1986-01-01

Data on preparation methods, structure and properties of chromates (3, 5) and mixed chromates (3) of rare earths, scandium and yttrium are generalized. Phase diagrams of systems Ln 2 O 3 -Cr 2 O 3 (Ln - rare earths, Sc, Y), chemical and thermodynamic properties of chromates (3, 5), their crystal structure and character of thermal decomposition are considered. Application fields of the compounds mentioned are suggested

Time-dependent transcriptional response of GOT1 human small intestine neuroendocrine tumor after 177Lu[Lu]-octreotate therapy.

Science.gov (United States)

Spetz, Johan; Rudqvist, Nils; Langen, Britta; Parris, Toshima Z; Dalmo, Johanna; Schüler, Emil; Wängberg, Bo; Nilsson, Ola; Helou, Khalil; Forssell-Aronsson, Eva

2018-05-01

Patients with neuroendocrine tumors expressing somatostatin receptors are often treated with 177 Lu[Lu]-octreotate. Despite being highly effective in animal models, 177 Lu[Lu]-octreotate-based therapies in the clinical setting can be optimized further. The aims of the study were to identify and elucidate possible optimization venues for 177 Lu[Lu]-octreotate tumor therapy by characterizing transcriptional responses in the GOT1 small intestine neuroendocrine tumor model in nude mice. GOT1-bearing female BALB/c nude mice were intravenously injected with 15 MBq 177 Lu[Lu]-octreotate (non-curative amount) or mock-treated with saline solution. Animals were killed 1, 3, 7 or 41 d after injection. Total RNA was extracted from the tumor samples and profiled using Illumina microarray expression analysis. Differentially expressed genes were identified (treated vs. control) and pathway analysis was performed. Distribution of differentially expressed transcripts indicated a time-dependent treatment response in GOT1 tumors after 177 Lu[Lu]-octreotate administration. Regulation of CDKN1A, BCAT1 and PAM at 1 d after injection was compatible with growth arrest as the initial response to treatment. Upregulation of APOE and BAX at 3 d, and ADORA2A, BNIP3, BNIP3L and HSPB1 at 41 d after injection suggests first activation and then inhibition of the intrinsic apoptotic pathway during tumor regression and regrowth, respectively. Transcriptional analysis showed radiation-induced apoptosis as an early response after 177 Lu[Lu]-octreotate administration, followed by pro-survival transcriptional changes in the tumor during the regrowth phase. Time-dependent changes in cell cycle and apoptosis-related processes suggest different time points after radionuclide therapy when tumor cells may be more susceptible to additional treatment, highlighting the importance of timing when administering multiple therapeutic agents. Copyright © 2018 The Authors. Published by Elsevier Inc. All

Pulsed laser deposition of epitaxial yttrium iron garnet films with low Gilbert damping and bulk-like magnetization

Directory of Open Access Journals (Sweden)

M. C. Onbasli

2014-10-01

Full Text Available Yttrium iron garnet (YIG, Y 3Fe5O12 films have been epitaxially grown on Gadolinium Gallium Garnet (GGG, Gd3Ga5O12 substrates with (100 orientation using pulsed laser deposition. The films were single-phase, epitaxial with the GGG substrate, and the root-mean-square surface roughness varied between 0.14 nm and 0.2 nm. Films with thicknesses ranging from 17 to 200 nm exhibited low coercivity (<2 Oe, near-bulk room temperature saturation moments (∼135 emu cm−3, in-plane easy axis, and damping parameters as low as 2.2 × 10−4. These high quality YIG thin films are useful in the investigation of the origins of novel magnetic phenomena and magnetization dynamics.

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

International Nuclear Information System (INIS)

Hackbarth, Liisa

2015-01-01

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

The Gd14Ag51 structure type and its relation to some complex amalgam structures

International Nuclear Information System (INIS)

Tambornino, Frank; Sappl, Jonathan; Hoch, Constantin

2015-01-01

Highlights: • The Gd 14 Ag 51 structure type has been revisited on the basis of single crystal diffraction data. • Symmetry analysis from electron density and TEM shows the space group P6/m to be true. • Gd 14 Ag 51 shows good metallic behaviour. • Structure relations to alkali, alkaline-earth and rare-earth metal amalgams can be established. • Complexity values for the RE 14 Ag 51 structure family were calculated. - Abstract: A plethora of binary and ternary intermetallic compounds has been assigned to the Gd 14 Ag 51 structure type, crystallising in the hexagonal system (space group P6/m, a = 1264.30(18) pm, c = 933.58(11) pm for Gd 14 Ag 51 ). Starting in the late 1960s, much work has been invested in the structural elucidation of these crystal structures. However, reliable single crystal data are scarce, and most structure type assignments have been performed merely on the basis of powder data. We have redetermined four representatives of the binary RE 14 Ag 51 structure type (RE = Y, Ce, Gd, Tb) with modern high-precision single crystal X-ray methods. The assignment of the Gd 14 Ag 51 structure type to space group P6/m was additionally verified by careful analysis of high resolution transmission electron micrographs. We emphasise the close relation of the Gd 14 Ag 51 structure type to the structures of some recently described amalgams of similar composition focussing on disorder phenomena and structural complexity. Furthermore, we provide detailed information on synthesis as well as electrical and magnetic properties for Gd 14 Ag 51 , the parent compound of this structure family

Luminescent properties of LuPO4-Pr and LuPO4-Eu nanoparticles

International Nuclear Information System (INIS)

Vistovskyy, V.; Malyi, T.; Vas’kiv, A.; Chylii, M.; Mitina, N.; Zaichenko, A.; Gektin, A.; Voloshinovskii, A.

2016-01-01

Spectral-luminescence parameters of LuPO 4 -Eu and LuPO 4 -Pr nanoparticles of different sizes are studied upon excitation by the synchrotron radiation with photon energies 4–40 eV. Influence of the nanoparticle size on Eu 3+ and Pr 3+ impurity luminescence is analyzed for intracenter and recombination excitation. It is shown that the luminescence intensity of impurities in the case of recombination excitation significantly stronger decreases with decreasing of nanoparticle size compared to intracenter excitation. This feature is explained by the influence of thermalization length to nanoparticle size ratio on the recombination luminescence. Electron recombination luminescence inherent for LuPO 4 -Eu nanoparticles shows a weaker dependence on the nanoparticle size than the hole one in LuPO 4 -Pr nanoparticles. The difference between energy states of praseodymium impurity ions in nanoparticles of different sizes is revealed.

Micro-alloying Mg with Y, Ce, Gd and La for texture modification-A comparative study

International Nuclear Information System (INIS)

Stanford, N.

2010-01-01

A comparative study of the effectiveness of Y, La, Ce and Gd as texture modifiers during the extrusion of magnesium-based alloys has been carried out. It was found that La, Ce and Gd are all effective texture modifiers, being able to produce the 'rare earth' texture at the low alloying levels of 300, 400 and 600 ppm respectively. Y was not as effective as the other three elements in modifying the texture, and at no concentration studied did this element form a typical 'rare earth' texture. It is proposed that a strong interaction of solutes with dislocations and grain boundaries is responsible for the significant impact rare earth additions have on the extruded grain size and texture at very low alloying levels.

Ion beam analysis of GdN thin films with a protective GaN capping layer

International Nuclear Information System (INIS)

Granville, S.; Budde, F.; Koo, A.; Ruck, B.J.; Trodahl, H.J.; Bittar, A.; Metson, J.B.; Kennedy, V.J.; Markwitz, A.; Prince, K.E.; Atanacio, A.

2005-01-01

Rare-earth nitrides represent an interesting class of matrials that exhibit a range of electronic and magnetic properties. Recent LSD+SIC calculations have predicted magnetic properties covering paramagnetic, ferromagnetic, and antiferromagnetic, and elecronic states including metallic, semiconducting, or insulating, and a number exhibit half-metallicity. Due to this wide variety of predicted properties these materials are of considerable interest as potential sources of spin-polarised current for novel devices. Although numerous studies of the rare-earth nitrides are present in the literature, there is still much to be learned about them. The most well studied of these nitrides is GdN, a ferromagnet with the highest Curie temperature of the series. The magnetic properties in particular have been extensively studied, but often the presence of impurities such as O could not be ruled out, and studies have shown that N vacancies or O impurities significantly influence the magnetic quality of GdN. The rare-earth nitrides are sensitive to water vapour and react rapidly upon exposure to atmosphere, so it is an ongoing challenge to produce GdN of a sufficient purity to make characterising its properties an achievable task. In particular the electrical and optical properties of stoichiometric GdN have not both been established reliably, despite their great relevance to the potential usefulness of the material in devices. (author). 5 refs., 2 figs

Studies on the pressed yttrium oxide-tungsten matrix as a possible dispenser cathode material

Energy Technology Data Exchange (ETDEWEB)

Yang, Fan; Wang, Jinshu, E-mail: wangjsh@bjut.edu.cn; Liu, Wei; Liu, Xiang; Zhou, Meiling

2015-01-15

Yttrium oxide was chosen as the secondary emission substance based on calculation results through first principle theory method. A new kind of pressed yttrium oxide-tungsten matrix dispenser cathodes are prepared by a sol–gel method combined with high temperature sintering in dry hydrogen atmosphere. The results show that the growth of the grains is hampered by the pinning effect of Y{sub 2}O{sub 3} distributing uniformly between the tungsten particles, resulting in the formation of small grain size. It is found that Y{sub 2}O{sub 3} improves the secondary electron emission property, i.e., the secondary emission yield increases with the increase of Y{sub 2}O{sub 3} content in the samples. The maximum secondary emission yield δ{sub max} of the cathode with 15% amount of Y{sub 2}O{sub 3} can reach 2.92. Furthermore, the cathode shows a certain thermionic emission performance. The zero field emission current density J{sub 0} of 4.18A/cm{sup 2} has reached at 1050 °C{sub b} for this kind of cathode after being activated at 1200 °C{sub b}, which are much higher than that of rare earth oxide doped molybdenum (REO-Mo) cathode reported in the previous work. - Highlights: • Yttrium oxide was chosen as the secondary emission substance based on first principle calculation result. • A new kind of cathode has been successfully obtained. • Pressed yttrium oxide-tungsten matrix dispenser cathode exhibits good emission properties. • The improvement of the cathode emission can be well explained by the surface analysis results presented in this work.

New anisotropic rare earth fluorides BaR2F8(R=Y,Dy-Lu): growth and characterization

International Nuclear Information System (INIS)

Kaminskii, A.A.; Butashin, A.V.; Sulyanov, S.N.; Bagayev, S.N.; Eichler, H.J.; Findeisen, J.; Liu, B.; Taeuber, U.; Peuser, P.

1998-01-01

Polymorphism of BaR 2 F 8 compounds is analyzed, and some peculiarities of the crystal growth from the melt are discussed. We report on the orthorhombic BaLu 2 F 8 crystal with ordered structure, a new crystalline material for generating Ln 3+ activator ions. Spectroscopic and laser characteristics of Nd 3+ - and Er 3+ -doped BaLu 2 F 8 samples are discussed as representative examples. Besides, we pay special attention to monoclinic BaY 2 F 8 :Er 3+ crystals, as active media for highly efficient CW 3 μm laser-diode pumped lasers. (orig.)

Large magnetocaloric effect of GdNiAl{sub 2} compound

Energy Technology Data Exchange (ETDEWEB)

Dembele, S.N.; Ma, Z.; Shang, Y.F. [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Fu, H., E-mail: fuhao@uestc.edu.cn [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Balfour, E.A. [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Hadimani, R.L.; Jiles, D.C. [Department of Electrical and Computer Engineering, Iowa State University, Ames, IA 50011 (United States); Ames Laboratory, US Department of Energy, Ames, IA 50011 (United States); Teng, B.H.; Luo, Y. [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China)

2015-10-01

This paper presents the structure, magnetic properties, and magnetocaloric effect of the polycrystalline compound GdNiAl{sub 2}. Powder X-ray diffraction (XRD) measurement and Rietveld refinement revealed that GdNiAl{sub 2} alloy is CuMgAl{sub 2}-type phase structure with about 1 wt% GdNi{sub 2}Al{sub 3} secondary phase. Magnetic measurements suggest that the compound is ferromagnetic and undergoes a second-order phase transition near 28 K. The maximum value of magnetic entropy change reaches 16.0 J/kg K for an applied magnetic field change of 0–50 kOe and the relative cooling power was 6.4×10{sup 2} J/kg. It is a promising candidate as a magnetocaloric material working near liquid hydrogen temperature (~20 K) exhibiting large relative cooling power. - Highlights: • Preferred orientation with axis of [010] was found in the GdNiAl{sub 2} compound. • The ΔS{sub Mmax} and the RCP are 16.0 J/kg K and 640 J/kg, respectively, for ΔH=50 kOe. • Relative low rare earth content in GdNiAl{sub 2} comparing with other candidates.

Behavior of Gd-DTPA in simulated bank filtration

International Nuclear Information System (INIS)

Moeller, Peter; Knappe, Andrea; Dulski, Peter; Pekdeger, Asaf

2011-01-01

Research highlights: → Gd-DTPA and similar products are common pollutants in surface and groundwater and prove to be a reliable monitor for mixing of groundwater with surface water loaded with effluents from sewage treatment plants. → Within a 30 m column filled with Pleistocene sand Gd-DTPA is reduced by 16% only within one month time by transmetallation. → Artificial bank filtration is not very effective in reducing Gd-DTPA in infiltrating water. - Abstract: The behavior of Gd-DTPA during bank filtration was simulated in a 30 m column filled with Pleistocene sand and flushed by surface water from a lakeside in Berlin, Germany. The surface water is about a 1:1 mixture of river water and effluents from a sewage treatment plant. Throughout 34 days this water was continuously spiked with Gd-DTPA at a level of 60 μg/L. The broad plateau of the Gd-DTPA pulse declined by 15.4% within 34 days by transmetallation. Nine percentage of the total decline is caused by Y and rare earth elements; the remaining part is attributed to Cu 2+ which is the most influential metal in surface water. All other metals also contributing to transmetallation are combined with Cu to Cu equivalents because only the rate constant of transmetallation of Cu 2+ is known. The analytical results of the column effluents prove the pseudo-first-order kinetics of transmetallation based on reversible sorption of metals by pools in the column sediment and disprove biodegradation at noticeable levels. The mass ratio of water to tracer is 10 .

Behavior of Gd-DTPA in simulated bank filtration

Energy Technology Data Exchange (ETDEWEB)

Moeller, Peter, E-mail: pemoe@gfz-potsdam.de [Freie Universitaet Berlin, Malteserstr. 74-100, AB Hydrogeologie, 12249 Berlin (Germany)] [Helmholtz Zentrum Potsdam, Deutsches GeoForschungsZentrum, Telegrafenberg, 14473 Potsdam (Germany); Knappe, Andrea [Freie Universitaet Berlin, Malteserstr. 74-100, AB Hydrogeologie, 12249 Berlin (Germany); Dulski, Peter [Helmholtz Zentrum Potsdam, Deutsches GeoForschungsZentrum, Telegrafenberg, 14473 Potsdam (Germany); Pekdeger, Asaf [Freie Universitaet Berlin, Malteserstr. 74-100, AB Hydrogeologie, 12249 Berlin (Germany)

2011-01-15

Research highlights: {yields} Gd-DTPA and similar products are common pollutants in surface and groundwater and prove to be a reliable monitor for mixing of groundwater with surface water loaded with effluents from sewage treatment plants. {yields} Within a 30 m column filled with Pleistocene sand Gd-DTPA is reduced by 16% only within one month time by transmetallation. {yields} Artificial bank filtration is not very effective in reducing Gd-DTPA in infiltrating water. - Abstract: The behavior of Gd-DTPA during bank filtration was simulated in a 30 m column filled with Pleistocene sand and flushed by surface water from a lakeside in Berlin, Germany. The surface water is about a 1:1 mixture of river water and effluents from a sewage treatment plant. Throughout 34 days this water was continuously spiked with Gd-DTPA at a level of 60 {mu}g/L. The broad plateau of the Gd-DTPA pulse declined by 15.4% within 34 days by transmetallation. Nine percentage of the total decline is caused by Y and rare earth elements; the remaining part is attributed to Cu{sup 2+} which is the most influential metal in surface water. All other metals also contributing to transmetallation are combined with Cu to Cu equivalents because only the rate constant of transmetallation of Cu{sup 2+} is known. The analytical results of the column effluents prove the pseudo-first-order kinetics of transmetallation based on reversible sorption of metals by pools in the column sediment and disprove biodegradation at noticeable levels. The mass ratio of water to tracer is <10{sup 10}.

X-ray absorption in GaGdN: A study of local structure

Science.gov (United States)

Martínez-Criado, G.; Sancho-Juan, O.; Garro, N.; Sans, J. A.; Cantarero, A.; Susini, J.; Roever, M.; Mai, D.-D.; Bedoya-Pinto, A.; Malindretos, J.; Rizzi, A.

2008-07-01

In this study, we report on the incorporation of dilute Gd amounts into GaN films grown by molecular beam epitaxy. A combination of x-ray fluorescence with x-ray absorption spectroscopic techniques enabled us to examine not only the distribution of rare earth atoms in the GaN matrix but also the short-range structural order. Our results show Gd atoms in a trivalent state with tetrahedral coordination, thus substituting Ga in the wurtzite GaN structure.

X-ray absorption in GaGdN: A study of local structure

International Nuclear Information System (INIS)

Martinez-Criado, G.; Sans, J. A.; Susini, J.; Sancho-Juan, O.; Cantarero, A.; Garro, N.; Roever, M.; Mai, D.-D.; Bedoya-Pinto, A.; Malindretos, J.; Rizzi, A.

2008-01-01

In this study, we report on the incorporation of dilute Gd amounts into GaN films grown by molecular beam epitaxy. A combination of x-ray fluorescence with x-ray absorption spectroscopic techniques enabled us to examine not only the distribution of rare earth atoms in the GaN matrix but also the short-range structural order. Our results show Gd atoms in a trivalent state with tetrahedral coordination, thus substituting Ga in the wurtzite GaN structure

Method for chromatographically recovering scandium and yttrium

International Nuclear Information System (INIS)

Snyder, T.S.; Stoltz, R.A.

1991-01-01

This paper describes a method for chromatographically recovering scandium and yttrium from the residue of a sand chlorinator. It comprises: providing a residue from a sand chlorinator, the residue containing scandium, yttrium, sodium, calcium and at least one radioactive metal of the group consisting of radium, thorium and uranium; digesting the residue with an acid to produce an aqueous liquid containing scandium, yttrium, sodium, calcium and at least one radioactive metal of the group consisting of radium, thorium and uranium; feeding the metal containing liquid through a cation exchanger; eluding the cation exchanger with an acid eluant to to produce: a first eluate containing at least half of the total weight of the calcium and sodium in the feed liquid; a second eluate containing at least half of the total weight of the one or more radioactive metals in the feed liquid; a third eluate containing at least half of the yttrium in the feed liquid, and a fourth eluate containing at least half of the weight of the scandium in the feed liquid

Reaction of yttrium polonides with carbon dioxide

International Nuclear Information System (INIS)

Abakumov, A.S.; Khokhlov, A.D.; Reznikova, N.F.

1986-01-01

It has been proved that heating of yttrium and tantalum in carbon dioxide to 500 and 800 0 C alters the gas phase composition, causing formation of carbon monoxide and reduction of oxygen content. A study of the thermal stability of yttrium polonides in carbon dioxide showed that yttrium sesqui- and monopolonides decompose at 400-430 0 C. The temperature dependence of the vapor pressure of polonium obtained upon decomposition of the referred polonides has been determined in a carbon dioxide environment radiotensometrically. The enthalpy of the process calculated from this dependence is close to the enthalpy of vaporization of elemental polonium in vacuo. The mechanism of the reactions has been suggested

Gd-Ni-Si system

International Nuclear Information System (INIS)

Bodak, O.I.; Shvets, A.F.

1983-01-01

By X-ray phase analysis method isothermal cross section of phase diagram of the Gd-Ni-Si system at 870 K is studied. The existence of nine previously known compounds (GdNisub(6.72)Sisub(6.28), GdNi 10 Si 2 , GdNi 5 Si 3 , GdNi 4 Si, GdNi 2 Si 2 , GdNiSi 3 , GdNiSi 2 , Gd 3 Ni 6 Si 2 and GdNiSi) is confirmed and three new compounds (GdNisub(0.2)Sisub(1.8), Gdsub(2)Nisub(1-0.8)Sisub(1-1.2), Gd 5 NiSi 4 ) are found. On the base of Gd 2 Si 3 compound up to 0.15 at. Ni fractions, an interstitial solid solution is formed up to 0.25 at Ni fractions dissolution continues of substitution type. The Gd-Ni-Si system is similar to the Y-Ni-Si system

Trace rare earth analysis by neutron activation and γ-ray/x-ray spectrometry

International Nuclear Information System (INIS)

Laul, J.C.; Nielson, K.K.; Wogman, N.A.

1977-01-01

A rare earth group separation scheme followed by photon energy analysis using Ge(Li) and intrinsic Ge detectors enhances significantly the detection of individual rare earth elements (REE) at or below the ppb level. Based on the x-ray and selected γ-ray energies, Ge(Li) γ-ray counting is favorable for 140 La, 141 Ce, 142 Pr, 153 Sm, 171 Er, and 177 Lu, whereas intrinsic Ge γ-ray counting is favorable for 143 Ce, 147 Nd, 160 Tb, and 166 Ho, and intrinsic Ge x-ray counting is favorable for 152 Eu and 175 Yb. Gamma-ray counting of 153 Gd and 170 Tm is equally sensitive with Ge(Li) or intrinsic Ge detectors. Precise measurements of the REE were made in the USGS geological samples BCR-1, W-1, AGV-1, G2, GSP-1 and PCC-1, the IAEA Soil-5, and the NBS orchard leaf and bovine liver standards. Their chondritic normalized REE patterns behave as a smooth function of the REE ionic radii. Interestingly, the REE patterns observed in orchard leaf and other plants are identical to the REE pattern in bovine liver. This comparison leads us to suggest that the plant REE patterns are probably not further fractionated by animals such as bovine during their dietary plant uptake

Yttrium implantation effects on extra low carbon steel and pure iron

Energy Technology Data Exchange (ETDEWEB)

Caudron, E.; Buscail, H. [Clermont-Ferrand-2 Univ., Le Puy en Velay (France). Lab. Vellave d`Elaboration; Jacob, Y.P.; Stroosnijder, M.F. [Institute for Advanced Materials, Joint Research Center, The European Commission, 21020, Ispra (Vatican City State, Holy See) (Italy); Josse-Courty, C. [Laboratoire de Recherche sur la Reactivite des Solides, UMR 56-13 CNRS, UFR Sciences et Techniques, 9 Avenue A. Savary, B.P. 400, 21011, Dijon Cedex (France)

1999-05-25

Extra low carbon steel and pure electrolytic iron samples were yttrium implanted using ion implantation technique. Compositions and structures of pure iron and steel samples were investigated before and after yttrium implantation by several analytical and structural techniques (RBS, SIMS, RHEED and XRD) to observe the yttrium implantation depth profiles in the samples. This paper shows the different effects of yttrium implantations (compositions and structures) according to the implanted sample nature. (orig.) 23 refs.

Chemical bonding and magnetic properties of gadolinium (Gd) substituted cobalt ferrite

Energy Technology Data Exchange (ETDEWEB)

Puli, Venkata Sreenivas, E-mail: vspuli@utep.edu [Department of Mechanical Engineering, University of Texas, El Paso, TX 79968 (United States); Adireddy, Shiva [Department of Physics and Engineering Physics, Tulane University, New Orleans, LA 70118 (United States); Ramana, C.V. [Department of Mechanical Engineering, University of Texas, El Paso, TX 79968 (United States)

2015-09-25

Graphical abstract: Room temperature Raman spectra of CoFe{sub 2−x}Gd{sub x}O{sub 4} (CFGO, x = 0.0–0.3) compounds as a function of wavenumber (cm{sup −1}). - Highlights: • Gd substituted ferrites were synthesized under controlled concentration. • Gd ion induced lattice dynamical changes are significant. • Enhanced magnetization is observed upon Gd-incorporation in cobalt ferrite. • A correlation between lattice dynamics and magnetic properties is established. - Abstract: Polycrystalline gadolinium (Gd) substituted cobalt ferrites (CoFe{sub 2−x}Gd{sub x}O{sub 4}; x = 0–0.3, referred to CFGO) ceramics have been synthesized by solid state reaction method. Chemical bonding, crystal structure and magnetic properties of CFGO compounds have been evaluated as a function of Gd-content. X-ray diffraction (XRD) and Raman spectroscopic analyses confirmed the formation of inverse spinel cubic structure. However, a secondary ortho-ferrite phase (GdFeO{sub 3}) nucleates for higher values of Gd-content. A considerable increase in the saturation magnetization has been observed upon the initial substitution of Gd (x = 0.1). The saturation magnetization drastically decreases at higher Gd content (x ⩾ 0.3). No contribution from ortho-ferrite GdFeO{sub 3} phase is noted to the magnetic properties. The increase in the magnetic saturation magnetization is attributed to the higher magnetic moment of Gd{sup 3+} (4f{sup 7}) residing in octahedral sites is higher when compared to that of Fe{sup 3+} (3d{sup 5}) and as well due to the migration of Co{sup 2+} (3d{sup 7}) ions from the octahedral to the tetrahedral sites with a magnetic moment aligned anti-parallel to those of rare earth (RE{sup 3+}) ions in the spinel lattice. Increase in coercivity with increase in Gd{sup 3+} is content is attributed to magnetic anisotropy in the ceramics.

Cohort study of somatostatin-based radiopeptide therapy with [(90)Y-DOTA]-TOC versus [(90)Y-DOTA]-TOC plus [(177)Lu-DOTA]-TOC in neuroendocrine cancers.

Science.gov (United States)

Villard, Linda; Romer, Anna; Marincek, Nicolas; Brunner, Philippe; Koller, Michael T; Schindler, Christian; Ng, Quinn K T; Mäcke, Helmut R; Müller-Brand, Jan; Rochlitz, Christoph; Briel, Matthias; Walter, Martin A

2012-04-01

Radiopeptide therapy is commonly performed with a single radioisotope. We aimed to compare the effectiveness of somatostatin-based radiopeptide therapy with a single versus a combination of radioisotopes. In a cohort study, patients with metastasized neuroendocrine cancer were treated with repeated cycles of (90)yttrium-labeled tetraazacyclododecane-tetraacetic acid modified Tyr-octreotide ([(90)Y-DOTA]-TOC) or with cycles alternating between [(90)Y-DOTA]-TOC and (177)lutetium-labeled DOTA-TOC ([(177)Lu-DOTA]-TOC) until tumor progression or permanent toxicity. Multivariable Cox regression and competing risk regression were used to study predictors of survival and renal toxicity in patients completing three or more treatment cycles. A total of 486 patients completed three or more treatment cycles; 237 patients received [(90)Y-DOTA]-TOC and 249 patients received [(90)Y-DOTA]-TOC + [(177)Lu-DOTA]-TOC. Patients receiving [(90)Y-DOTA]-TOC + [(177)Lu-DOTA]-TOC had a significantly longer survival than patients receiving [(90)Y-DOTA]-TOC alone (5.51 v 3.96 years; hazard ratio, 0.64; 95% CI, 0.47 to 0.88; P = .006). The rates of severe hematologic toxicities (6.3% v 4.4%; P = .25) and severe renal toxicity (8.9% v 11.2%; P = .47) were comparable in both groups. [(90)Y-DOTA]-TOC + [(177)Lu-DOTA]-TOC was associated with improved overall survival compared with [(90)Y-DOTA]-TOC alone in patients completing three or more cycles of treatment. Contrary to the current practice in radiopeptide therapy, our results suggest an advantage of using a combination of radioisotopes.

First-principles study of electronic and elastic properties of LuAl{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Shukla, Pushplata, E-mail: pujashukla50@gmail.com; Shrivastava, Deepika; Sanyal, Sankar P. [Department of Physics, Barkatullah university, Bhopal 462026 (India)

2016-05-06

A systematic theoretical study of electronic structure of rare earth intermetallic LuAl{sub 3} has been carried out using full potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT) within the generalized gradient approximation(GGA) for exchange and correlation potential. The ground state properties such as lattice constant (a{sub o}), bulk modulus (B) and pressure derivative of bulk modulus (B′) were evaluated. LuAl{sub 3} has the cubic AuCu{sub 3} type crystal structure. The electronic properties of this compound have been analyzed quantatively from band structure and DOS. It is clear from band structure that this compound is metallic in nature. The calculated elastic constants infer that this compound is mechanically stable.

LuFLA1PRO and LuBGAL1PRO promote gene expression in the phloem fibres of flax (Linum usitatissimum).

Science.gov (United States)

Hobson, Neil; Deyholos, Michael K

2013-04-01

Cell type-specific promoters were identified that drive gene expression in an industrially important product. To identify flax (Linum usitatissimum) gene promoters, we analyzed the genomic regions upstream of a fasciclin-like arabinogalactan protein (LuFLA1) and a beta-galactosidase (LuBGAL1). Both of these genes encode transcripts that have been found to be highly enriched in tissues bearing phloem fibres. Using a beta-glucuronidase (GUS) reporter construct, we found that a 908-bp genomic sequence upstream of LuFLA1 (LuFLA1PRO) directed GUS expression with high specificity to phloem fibres undergoing secondary cell wall development. The DNA sequence upstream of LuBGAL1 (LuBGAL1PRO) likewise produced GUS staining in phloem fibres with developing secondary walls, as well as in tissues of developing flowers and seed bolls. These data provide further evidence of a specific role for LuFLA1 in phloem fibre development, and demonstrate the utility of LuFLA1PRO and LuBGAL1PRO as tools for biotechnology and further investigations of phloem fibre development.

Gd3+-ESR and magnetic susceptibility of GdCu4Al8 and GdMn4Al8

International Nuclear Information System (INIS)

Coldea, R.; Coldea, M.; Pop, I.

1994-01-01

Gd ESR of GdCu 4 Al 8 and GdMn 4 Al 8 and magnetic susceptibility of GdCu 4 Al 8 , GdMn 4 Al 8 , and YMn 4 Al 8 were measured in the temperature range of 290K--460K and 90K--1050K, respectively. The occurrence of the Mn moment in YMn 4 Al 8 and GdMn 4 Al 8 is strongly correlated with the critical value of d∼2.6 angstrom of the Mn-Mn distance below which the Mn moment is not stable. The experimental data for GdMn 4 Al 8 , compared with the data for the isostructural compounds GdCu 4 Al 8 and YMn 4 Al 8 , show that near the critical value of d, the existence of Mn moment depends not only on the value of d, but also on the local magnetic surroundings. It has been revealed that the magnetic character of Mn moment in YMn 4 Al 8 and GdMn 4 Al 8 changes from an itinerant electron type to a local-moment type with increasing temperature

Ultrasensitive interplay between ferromagnetism and superconductivity in NbGd composite thin films

Science.gov (United States)

Bawa, Ambika; Gupta, Anurag; Singh, Sandeep; Awana, V. P. S.; Sahoo, Sangeeta

2016-01-01

A model binary hybrid system composed of a randomly distributed rare-earth ferromagnetic (Gd) part embedded in an s-wave superconducting (Nb) matrix is being manufactured to study the interplay between competing superconducting and ferromagnetic order parameters. The normal metallic to superconducting phase transition appears to be very sensitive to the magnetic counterpart and the modulation of the superconducing properties follow closely to the Abrikosov-Gor’kov (AG) theory of magnetic impurity induced pair breaking mechanism. A critical concentration of Gd is obtained for the studied NbGd based composite films (CFs) above which superconductivity disappears. Besides, a magnetic ordering resembling the paramagnetic Meissner effect (PME) appears in DC magnetization measurements at temperatures close to the superconducting transition temperature. The positive magnetization related to the PME emerges upon doping Nb with Gd. The temperature dependent resistance measurements evolve in a similar fashion with the concentration of Gd as that with an external magnetic field and in both the cases, the transition curves accompany several intermediate features indicating the traces of magnetism originated either from Gd or from the external field. Finally, the signatures of magnetism appear evidently in the magnetization and transport measurements for the CFs with very low (<1 at.%) doping of Gd.

Probing the superconducting ground state of the rare-earth ternary boride superconductors R RuB2 (R = Lu,Y) using muon-spin rotation and relaxation

Science.gov (United States)

Barker, J. A. T.; Singh, R. P.; Hillier, A. D.; Paul, D. McK.

2018-03-01

The superconductivity in the rare-earth transition-metal ternary borides R RuB2 (where R =Lu and Y) has been investigated using muon-spin rotation and relaxation. Measurements made in zero field suggest that time-reversal symmetry is preserved upon entering the superconducting state in both materials; a small difference in depolarization is observed above and below the superconducting transition in both compounds, however, this has been attributed to quasistatic magnetic fluctuations. Transverse-field measurements of the flux-line lattice indicate that the superconductivity in both materials is fully gapped, with a conventional s -wave pairing symmetry and BCS-like magnitudes for the zero-temperature gap energies. The electronic properties of the charge carriers in the superconducting state have been calculated, with effective masses m*/me=9.8 ±0.1 and 15.0 ±0.1 in the Lu and Y compounds, respectively, with superconducting carrier densities ns=(2.73 ±0.04 ) ×1028m-3 and (2.17 ±0.02 ) ×1028m-3 . The materials have been classified according to the Uemura scheme for superconductivity, with values for Tc/TF of 1 /(414 ±6 ) and 1 /(304 ±3 ) , implying that the superconductivity may not be entirely conventional in nature.

Electronic response of rare-earth magnetic-refrigeration compounds GdX2 (X = Fe and Co)

Science.gov (United States)

Bhatt, Samir; Ahuja, Ushma; Kumar, Kishor; Heda, N. L.

2018-05-01

We present the Compton profiles (CPs) of rare-earth-transition metal compounds GdX2 (X = Fe and Co) using 740 GBq 137Cs Compton spectrometer. To compare the experimental momentum densities, we have also computed the CPs, electronic band structure, density of states (DOS) and Mulliken population (MP) using linear combination of atomic orbitals (LCAO) method. Local density and generalized gradient approximations within density functional theory (DFT) along with the hybridization of Hartree-Fock and DFT (B3LYP and PBE0) have been considered under the framework of LCAO scheme. It is seen that the LCAO-B3LYP based momentum densities give a better agreement with the experimental data for both the compounds. The energy bands and DOS for both the spin-up and spin-down states show metallic like character of the reported intermetallic compounds. The localization of 3d electrons of Co and Fe has also been discussed in terms of equally normalized CPs and MP data. Discussion on magnetization using LCAO method is also included.

DTA AND MOSSBAUER STUDIES IN RARE EARTH ORTHOFERRITES

Energy Technology Data Exchange (ETDEWEB)

Eibschuetz, M.; Gorodetsky, G.; Shtrikman, S.; Treves, D.

1963-11-15

Curie temperatures of 14 different orthoferrites with the chemical formula RFeO/sub 3/ (R = Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were measured by differential thermal analysis. Hyperfine interactions of the Fe/ sup 57/ nucleus in the same materials were determined from their Mossbauer spectra. It is found that the quadrupole splitting with the exception of the case of Sm, isomer shift, Curie temperature, and internal field vary regularly with the ionic size of R. (auth)

Alaska's rare earth deposits and resource potential

Science.gov (United States)

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

2012-01-01

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

Magnetic and transport properties of amorphous ferro magnetic Gd--Au, Gd--Ni and Gd--Co alloys obtained by splat-cooling

International Nuclear Information System (INIS)

Durand, J.; Poon, S.J.

1977-06-01

We present the results of magnetization and transport measurements on the amorphous Gd 80 Au 20 , Gd 68 Ni 32 and Gd 67 Co 33 alloys over a temperature range of 1.8 to 300 0 K in fields up to 75 kOe. These ferromagnetic alloys obtained by splat-cooling have Curie temperatures T/sub c/ of 150, 125 and 175 0 K, respectively. The saturation moment per Gd atom extrapolated to 0 0 K is estimated to be 7 +- 0.1 μ/sub B/. The exchange integrals for Gd-Au and Gd-Ni are determined from the value of T/sub c/ and from the temperature dependence of the saturation magnetization. The zero-field resistivity for Gd-Ni and Gd-Co exhibits maxima around T/sub c/. We present some preliminary results of magnetoresistivity measurements with applied field parallel and perpendicular to the foil plane. The anisotropy is in-plane for Gd-Co. For the Gd-Au and Gd-Ni alloys, there is no well-defined easy axis

radiolabeling of DOTA-substance P with 177Lu and biodistribution of 177Lu-DOTA-substance P

International Nuclear Information System (INIS)

Liang Jixin; Li Hongyu; Xiang Xueqin; Luo Zhifu; Luo Hongyi; Hu Liansheng; Chen Yang; Zhuang Ling; Deng Xinrong

2012-01-01

The aim of this project is to evaluate the biodistribution of 177 Lu-DOTA-SP in normal mice and in PANC-1 tumor bearing nude mice and to pave the way for its potentially medical application. In this study, 177 Lu-DOTA-SP was successfully prepared with labeling yield of greater than 90% at optimized conditions and more than 98% of radiochemical purity after C18 Sep-Pak purification. 177 Lu-DOTA-SP showed good stability in saline and in 5% serum while it decomposed slowly in 10% serum. Biodistribution studies in normal mice showed high uptake of 177 Lu-DOTA-SP in the kidneys, indicating the excretion mainly by renal pathway. In addition, 177 Lu-DOTA-SP was washed out from the blood quickly. Bio- distribution of 177 Lu-DOTA-SP in PANC-1 tumor bearing mice showed higher uptake in pancreatic tumor than that in normal pancreas, indicating the presence of NK-1 receptors in PANC-1 pancreatic tumor. However, from SPECT image, no radioactivity accumulation was observed in PANC-1 tumor. Further evaluation is needed to confirm its potential application for radiotherapy of pancreatic cancers. (authors)

N-m-nitrocinnamoylphenylhydroxyl-amine as reagent for amperometric determination of yttrium

International Nuclear Information System (INIS)

Oliferenko, G.L.; Gallaj, Z.A.; Sheina, N.M.; Shvedene, N.V.

1983-01-01

Possibility of using organic reagent of unsaturated N-arylsubstituted derivatives class of hydroxamic acids N-m-nitrocinnamoyl phenylhydroxylamire (NCPHA) for amperometric titration of yttrium using indication of e.t.p. by current of reagent oxidation on graphite electrode is investigated. Metal and the NCPHA form difficultly soluble complex with ratio of yttrium to the NCPHA, which is equal to 1:3. Buffer mixtures of 0.1MNH 3 +0.1MCH 3 COOH composis tion with pH 6.3-7.5 are optimal background solutions for amperometric titration of yttrium. The proposed method permits to determine 10-600 μkg of yttrium in the volume of 10 ml. Effect of the series of strange elements on titration of yttrium with NCPHA (Ca, Mg, Mn (2), Al, CU (2), Fe (3) REE and others) is studied. The developed method is used for yttrium determination in luminophores of Casub(n)-- Ysub(m)Fsub(z)xMn(2) (1-10%) composition

Treatment of exhaust fluorescent lamps to recover yttrium: Experimental and process analyses

International Nuclear Information System (INIS)

De Michelis, Ida; Ferella, Francesco; Varelli, Ennio Fioravante; Veglio, Francesco

2011-01-01

Highlights: → Recovery of yttrium from spent fluorescent lamps by sulphuric acid leaching. → The use of sulphuric acid allows to reduce calcium dissolutions. → Main contaminant of fluorescent powder are Si, Pb, Ca and Ba. → Hydrated yttrium oxalate, recovered by selective precipitation, is quite pure (>90%). → We have studied the whole process for the treatment of dangerous waste (plant capability). - Abstract: The paper deals with recovery of yttrium from fluorescent powder coming from dismantling of spent fluorescent tubes. Metals are leached by using different acids (nitric, hydrochloric and sulphuric) and ammonia in different leaching tests. These tests show that ammonia is not suitable to recover yttrium, whereas HNO 3 produces toxic vapours. A full factorial design is carried out with HCl and H 2 SO 4 to evaluate the influence of operating factors. HCl and H 2 SO 4 leaching systems give similar results in terms of yttrium extraction yield, but the last one allows to reduce calcium extraction with subsequent advantage during recovery of yttrium compounds in the downstream. The greatest extraction of yttrium is obtained by 20% w/v S/L ratio, 4 N H 2 SO 4 concentration and 90 deg. C. Yttrium and calcium yields are nearly 85% and 5%, respectively. The analysis of variance shows that acid concentration alone and interaction between acid and pulp density have a significant positive effect on yttrium solubilization for both HCl and H 2 SO 4 medium. Two models are empirically developed to estimate yttrium and calcium concentration during leaching. Precipitation tests demonstrate that at least the stoichiometric amount of oxalic acid is necessary to recover yttrium efficiently and a pure yttrium oxalate n-hydrate can be produced (99% grade). The process is economically feasible if other components of the fluorescent lamps (glass, ferrous and non-ferrous scraps) are recovered after the equipment dismantling and valorized, besides the cost that is usually paid

Crystallization of Yttrium and Samarium Aluminosilicate Glasses

OpenAIRE

Lago, Diana Carolina; Prado, Miguel Oscar

2016-01-01

Aluminosilicate glasses containing samarium and yttrium (SmAS and YAS glasses) exhibit high glass transition temperatures, corrosion resistance, and glass stability on heating which make them useful for technological applications. Yttrium aluminosilicate glass microspheres are currently being used for internal selective radiotherapy of liver cancer. During the preparation process, crystallization needs to be totally or partially avoided depending on the final application. Thus knowing the cry...

Yttrium doped BSCF membranes for oxygen separation

DEFF Research Database (Denmark)

Haworth, P.; Smart, S.; Glasscock, Julie

2011-01-01

This work investigates the partial substitution of yttrium in place of iron in BSCF to form Ba0.5Sr0.5Co0.8Fe0.2−xYxO3−δ, where x varied between 0 and 0.2. X-ray diffraction patterns showed the formation of a perovskite cubic phase structure up to x = 0.15, whilst the full substitution of yttrium...

Preparation and study of the critical-mass-free plutonium ceramics with neutron poisons Hf, Gd and Li

International Nuclear Information System (INIS)

Timoefeeva, L.F.; Orlov, V.K.; Malyukov, E.E.; Molomin, V.I.; Zhmak, V.A.; Semova, E.A.; Shishkov, N.V.; Nadykto, B.A.

2002-01-01

Powder sintering was used to produce homogeneous type oxide ceramics of Pu with Hf, Gd and Li 6 . In all the ceramics, there is the number of neutron poison (Hf, Gd and Li) atoms per plutonium atom needed, according to the physical calculation, for them to be free of critical mass. PuO 2 stabilizers high-temperature modifications of cubic HfO 2 or hexagonal Gd 2 O 3 , however, at the ratio given by the physical calculation, the plutonium is insufficient for their full stabilization. Addition of yttrium oxide as an additive stabilizing the fcc phase of HfO 2 resulted in cubic solid solution (Pu, Hf, Y)O 2-x . Pu/Li/Hf and Pu/Li/Si ceramics produced by sintering of PuO 2 and compound Li 2 HfO 3 or 6 Li 4 SiO 4 powders is characterized with presence of two phases. The method of differential thermal analysis demonstrated the phase stability of (Pu-Hf, Pu-Gd, Pu-Li-Hf) oxide ceramics in the 20-1500degC temperature range. Ceramic (Pu/Li/Si) has several endothermal effects. Tests in boiling water solutions of various composition suggest that the specimens of Pu, Hf oxides and ternary oxides (Pu, Hf, Y)O 2 are less stable in weakly acidic media than in weakly alkaline medium and distilled water. The obtained results were used as a basis to estimate the assumed solid solution region boundaries for binary Hf, Pu and ternary Hf, Pu, Y oxides on the side of HfO 2 . (author)

Thermoanalytical study of the formation mechanism of yttria from yttrium acetate

International Nuclear Information System (INIS)

Farjas, J.; Camps, J.; Roura, P.; Ricart, S.; Puig, T.; Obradors, X.

2011-01-01

Highlights: → Thermal decomposition of yttrium acetate: three endothermic stages. → Intermediates: yttrium hydroxide and carbonate. → Product: cubic yttria (the degree of transformation is at least 99%). → The decomposition does not depend on the oxygen partial pressure. - Abstract: The processes involved in the thermal decomposition of yttrium acetate tetrahydrate, Y(CH 3 COO) 3 .4H 2 O, in air and in an inert atmosphere have been analyzed by thermoanalytical techniques (thermogravimetry, differential thermal analysis and evolved gas analysis) and by the structural characterization (X-ray diffraction, infrared spectroscopy, elemental analysis and scanning electron microscopy) of intermediates and final products. Decomposition of yttrium acetate is an endothermic transformation that takes place in a temperature range between 350 and 900 o C. The evolution of the mass during the decomposition process is not affected by the presence of oxygen. The process is initiated by the rupture of the bond between the metallic cation and the acetate ligand. This initial step (350-450 o C) involves the formation of amorphous yttrium hydroxide and yttrium carbonate and is characterized by a fast mass loss rate. A sudden decrease of the mass loss rate indicates a change in the decomposition kinetics that continues with the decomposition of yttrium hydroxide and yttrium carbonate. The main effect of an oxygen atmosphere is an intense exothermic process due to the combustion of organic species in the gas phase.

Effect of yttrium on electron–phonon coupling strength of 5d state of Ce3+ ion in LYSO:Ce crystals

International Nuclear Information System (INIS)

Ding, Dongzhou; Liu, Bo; Wu, Yuntao; Yang, Jianhua; Ren, Guohao; Chen, Junfeng

2014-01-01

This paper aims at an improved understanding of luminescence properties of (Lu 1−x Y x ) 2 SiO 5 :Ce (x=0 at%, 26 at%, 45 at%, 66 at% and 100 at%). Photoluminescence emission and excitation spectra as well as Raman spectra of (Lu 1−x Y x ) 2 SiO 5 :Ce were investigated as a function of yttrium (shortened as Y) content in it. Obtained Huang–Rhys factor S indicates that the coupling between Ce1 (7-oxygen-coordinated), Ce2 (6-oxygen-coordinated) and LYSO lattice is intermediate and strong, respectively. Besides, it was found that: with the increase of Y content, crystal field strength around Ce1 and Ce2 decreases, Stokes shift of Ce1 and Ce2 presents an increase trend, and S of Ce2 tends to decrease. These phenomena were explained by geometrical influence of Y 3+ /Lu 3+ on the crystal field splitting of the 5d levels of Ce 3+ and coupling strength. With the increase of Y content, the evolution of S and coupling energy ħω of Ce1 present a slight increase and decrease trend respectively, while S and coupling energy ħω of Ce2 present an obvious decrease and increase trend, respectively. - Highlights: • Crystal field strength around Ce1 decreases with increase of Y content in LYSO:Ce. • A diagram of Huang–Rhys factor S against Y content in LYSO:Ce was constructed. • A diagram of coupling energy ħω against Y content in LYSO:Ce was constructed. • A diagram of Stokes shift against Y content in LYSO:Ce was constructed

Labelling of 90Y- and 177Lu-DOTA-Bioconjugates for Targeted Radionuclide Therapy: A Comparison among Manual, Semiautomated, and Fully Automated Synthesis

Directory of Open Access Journals (Sweden)

Michele Iori

2017-01-01

Full Text Available In spite of the hazard due to the radiation exposure, preparation of 90Y- and 177Lu-labelled radiopharmaceuticals is still mainly performed using manual procedures. In the present study the performance of a commercial automatic synthesizer based on disposable cassettes for the labelling of 177Lu- and 90Y-DOTA-conjugated biomolecules (namely, DOTATOC and PSMA-617 was evaluated and compared to a manual and a semiautomated approach. The dose exposure of the operators was evaluated as well. More than 300 clinical preparations of both 90Y- and 177Lu-labelled radiopharmaceuticals have been performed using the three different methods. The mean radiochemical yields for 90Y-DOTATOC were 96.2±4.9%, 90.3±5.6%, and 82.0±8.4%, while for 177Lu-DOTATOC they were 98.3%  ± 0.6, 90.8%  ± 8.3, and 83.1±5.7% when manual, semiautomated, and automated approaches were used, respectively. The mean doses on the whole hands for yttrium-90 preparations were 0.15±0.4 mSv/GBq, 0.04±0.1 mSv/GBq, and 0.11±0.3 mSv/GBq for manual, semiautomated, and automated synthesis, respectively, and for lutetium-177 preparations, they were 0.02±0.008 mSv/GBq, 0.01±0.03 mSv/GBq, and 0.01±0.02 mSv/GBq, respectively. In conclusion, the automated approach guaranteed reliable and reproducible preparations of pharmaceutical grade therapeutic radiopharmaceuticals in a decent RCY. The radiation exposure of the operators remained comparable to the manual approach mainly due to the fact that a dedicated shielding was still not available for the system.

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-06-06

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

Assignment of 4f-5d absorption bands in Ce-doped RAlO.sub.3./sub. (R=La, Gd, Y, Lu) perovskites

Czech Academy of Sciences Publication Activity Database

Mihóková, Eva; Nikl, Martin; Bacci, M.; Dušek, Michal; Petříček, Václav

2009-01-01

Roč. 79, č. 19 (2009), 1951309/1-1951309/7 ISSN 1098-0121 R&D Projects: GA MŠk ME 903; GA AV ČR IAA100100810 Institutional research plan: CEZ:AV0Z10100521 Keywords : cerium * EHT calculations * gadolinium compounds * lanthanum compounds * lutetium compounds * ultraviolet spectra * yttrium compounds Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.475, year: 2009

Synthesis and luminescence studies of novel rare earth activated lanthanum pentaborate

International Nuclear Information System (INIS)

Nagpure, P.A.; Bajaj, N.S.; Omanwar, S.K.; Sonekar, R.P.

2011-01-01

The lanthanum pentaborate (LaB 5 O 9 ) is a novel material which exhibits excellent luminescence when doped with rare earth ions. It was prepared by a novel technique which is a slight variation of solution combustion synthesis. The synthesis is based on the exothermic reaction between the fuel (urea) and oxidizer (ammonium nitrate). The structure of the prepared material was confirmed by powder XRD technique. The photoluminescence of rare earth ions (Ce 3+ , Eu 3+ ) and sensitized luminescence of Gd 3+ (Pr 3+ -Gd 3+ and Bi 3+ -Gd 3+ ) in LaB 5 O 9 have been studied. LaB 5 O 9 :Ce 3+ shows broad band UV emission at 317 nm and LaB 5 O 9 :Eu 3+ shows orange red emission. LaB 5 O 9 : Pr 3+ -Gd 3+ and LaB 5 O 9 : Bi 3+ -Gd 3+ exhibit efficient luminescence of Gd 3+ in narrow UVB region at 310 nm. The material (La 0.5 Pr 0.4 )B 5 O 9 :Gd 0.1 exhibits intense narrow band UVB emission at 310 nm and could be a potential candidate for UVB phosphors used in phototherapy lamps. (author)

Blood clearance and occupational exposure for {sup 177}Lu-DOTATATE compared to {sup 177}Lu-PSMA radionuclide therapy

Energy Technology Data Exchange (ETDEWEB)

Abuqbeitah, Mohammad; Demir, Mustafa; Uslu-Besli, Lebriz; Yeyin, Nami; Soenmezoglu, Kerim [Istanbul University, Department of Nuclear Medicine, Cerrahpasa Faculty of Medicine, Istanbul (Turkey)

2018-03-15

The main target of this work is to examine blood clearance and external exposure for {sup 177}Lu-DOTATATE compared with new emerging {sup 177}Lu-PSMA therapy. Blood clearance and radiation exposure of 31 patients treated with 5.5 ± 1.1 GBq {sup 177}Lu-DOTATATE were compared to those of 23 patients treated with 7.4 GBq {sup 177}Lu-PSMA. Dose rates were measured at several distances and time points up to 120 h after treatment. Blood samples were collected conjunctively after infusion. Caregiver's cumulative dose was measured by means of an OSL (optically stimulated luminescence) dosimeter for 4-5 days and medical staff's dose was also estimated using electronic personal dosimeters. Finger dose was determined via ring TLD (Thermoluminescence Dosimeter) for radiopharmacists and nurses. Dose rates due to {sup 177}Lu-DOTATATE at a distance of 1 m, 4 h and 6 h after infusion, were 3.0 ± 2.8 and 2 ± 1.9 μSv/(h GBq), respectively, while those due to {sup 177}Lu-PSMA were 3.1 ± 0.8 and 2.2 ± 0.9 μSv/(h GBq). Total effective dose of 17 caregivers was 100-200 μSv for {sup 177}Lu-DOTATATE therapy. Mean effective doses to nurses and radiopharmacists were 5 and 4 μSv per patient, respectively, while those for physicists and physicians were 2 μSv per patient. For {sup 177}Lu-DOTATATE, effective half-life in blood and early elimination phase were 0.31 ± 0.13 and 4.5 ± 1 h, while they were found as 0.4 ± 0.1 and 5 ± 1 h, respectively, for {sup 177}Lu-PSMA. The first micturition time following {sup 177}Lu-DOTATATE infusion was noted after 36 ± 14 min, while the second and third voiding times were after 74 ± 9 and 128 ± 41 min, respectively. It is concluded that blood clearance and radiation exposure for {sup 177}Lu-DOTATATE are very similar to those for {sup 177}Lu-PSMA, and both treatment modalities are reasonably reliable for outpatient treatment, since the mean dose rate [2.1 μSv/(h GBq)] decreased below the dose rate that allows release of the patient

Studies on yttrium oxide coatings for corrosion protection against molten uranium

International Nuclear Information System (INIS)

Chakravarthy, Y.; Bhandari, Subhankar; Pragatheeswaran; Thiyagarajan, T.K.; Ananthapadmanabhan, P.V.; Das, A.K.; Kumar, Jay; Kutty, T.R.G.

2012-01-01

Yttrium oxide is resistant to corrosion by molten uranium and its alloys. Yttrium oxide is recommended as a protective oxide layer on graphite and metal components used for melting and processing uranium and its alloys. This paper presents studies on the efficacy of plasma sprayed yttrium oxide coatings for barrier applications against molten uranium

ESR of Gd3+ in magnetically ordered Eu2CuO4

International Nuclear Information System (INIS)

Rettori, C.; Oseroff, S.B.; Rao, D.; Valdivia, J.A.; Barberis, G.E.; Martins, G.B.; Sarrao, J.; Fisk, Z.; Tovar, M.

1996-01-01

Electron spin resonance (ESR) experiments of Gd 3+ in the antiferromagnetic (AF) ordered phase (T N ) of Eu 2 CuO 4 can be interpreted in terms of four magnetically nonequivalent rare-earth sites with local internal fields H i =±310(30) Oe along the [100] and [010] directions. The internal field is well described by a dipolar magnetic field of a noncollinear AF array of 0.35(4) μ B per Cu moment aligned along the [100] and [010] directions. This is consistent with recent results of magnetic-field-dependent neutron-diffraction experiments. From the ESR and magnetic susceptibility data, the crystal field parameters for Gd 3+ and Eu 3+ in Eu 2 CuO 4 are determined. The exchange parameters between the rare earths are also estimated. copyright 1996 The American Physical Society

Anomalies of magnetoresistance of compounds with atomic clusters RB12 (R = Ho, Er, Tm, Lu)

International Nuclear Information System (INIS)

Sluchanko, N. E.; Bogach, A. V.; Glushkov, V. V.; Demishev, S. V.; Samarin, N. A.; Sluchanko, D. N.; Dukhnenko, A. V.; Levchenko, A. V.

2009-01-01

The magnetoresistance and magnetization of single-crystal samples of rare-earth dodecaborides RB 12 (R = Ho, Er, Tm, Lu) have been measured at low temperatures (1.8-35 K) in a magnetic field of up to 70 kOe. The effect of positive magnetoresistance that obeys the Kohler's rule Δρ/ρ = f(ρ(0, 300 K)H/ρ(0, T)) is observed for the nonmagnetic metal LuB 12 . In the magnetic dodecaborides HoB 12 , ErB 12 , and TmB 12 , three characteristic regimes of the magnetoresistance behavior have been revealed: the positive magnetoresistance effect similar to the case of LuB 12 is observed at T > 25 K; in the range T N ≤ T ≤ 15 K, the magnetoresistance becomes negative and depends quadratically on the external magnetic field; and, finally, upon the transition to the antiferromagnetic phase (T N ), the positive magnetoresistance is again observed and its amplitude reaches 150% for HoB 12 . It has been shown that the observed anomalies of negative magnetoresistance in the paramagnetic phase can be explained within the Yosida model of conduction electron scattering by localized magnetic moments. The performed analysis confirms the formation of spin-polaron states in the 5d band in the vicinity of rare-earth ions in paramagnetic and magnetically ordered phases of RB 12 and makes it possible to reveal a number of specific features in the transformation of the magnetic structure of the compounds under investigation

Low-frequency dielectric dispersion and magnetic properties of La, Gd modified Pb(Fe1/2Ta1/2)O3 multiferroics

International Nuclear Information System (INIS)

Choudhury, R.N.P.; Rodriguez, C.; Bhattacharya, P.; Katiyar, R.S.; Rinaldi, C.

2007-01-01

Pb(Fe 1/2 Ta 1/2 )O 3 (PFT) modified by rare-earth (La and Gd) ions has been synthesized in a single phase using a double-stage synthesis (i.e., Columbite) technique. Scanning electron micrographs (SEM) of the pellet samples have shown a significant change in their grain size and uniform distribution of Gd/La at the Fe-sites. The room temperature X-ray structural analysis shows that the reported cubic (or tetragonal) structure of PFT has been distorted to a monoclinic system on substitution of La/Gd at the Fe-site. Detailed studies of dielectric properties of the above compound on La/Gd substitution have shown strong dielectric dispersion at low frequency (i.e. relaxor behavior) with drastic change in transition temperature. Magnetic characterization shows that though the PFT sample displays an antiferromagnetic transition at ∼150 K, the rare-earth ions-substituted samples do not. Furthermore, temperature dependence of magnetization measurements shows that spin glass transition observed in PFT at low temperatures (5-20 K) does not exist in the La and Gd substituted PFT. Doping of Gd in PFT increases the sample magnetization, especially at low temperature

Synthesis and Characterization of Gd2O3 Hollow Microspheres Using a Template-Directed Method

Directory of Open Access Journals (Sweden)

Xueliang Jiang

2016-04-01

Full Text Available Uniform rare-earth gadolinium oxide (Gd2O3 hollow microspheres, as formed through a urea-assisted homogenous precipitation process using carbon spheres as a template and a subsequent heat treatment, were characterized by using X-ray diffraction, Fourier transformed infared spectroscopy, thermogravimetry, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and Brunauer-Emmett-Tellet surface area measurement. The results indicate that the final products can be indexed to a cubic Gd2O3 phase with high purity and have a uniform morphology at 500 nm in diameter and 20 nm in shell thickness. The as-synthesized Gd2O3 hollow microspheres exhibited a superior photooxidation activity to that of Gd2O3 powder and an effect similar to P25, significantly broadening the potential of Gd2O3 hollow microspheres for many practical applications.

Rare earth-rich cadmium compounds RE{sub 10}TCd{sub 3} (RE = Y, Tb, Dy, Ho, Er, Tm, Lu; T = Rh, Pd, Ir, Pt) with an ordered Co{sub 2}Al{sub 5}-type structure

Energy Technology Data Exchange (ETDEWEB)

Block, Theresa; Klenner, Steffen; Heletta, Lukas; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

2018-04-01

Eighteen new rare earth-rich intermetallic phases RE{sub 10}TCd{sub 3} (RE = Y, Tb, Dy, Ho, Er, Tm, Lu; T = Rh, Pd, Ir, Pt) were obtained by induction melting of the elements in sealed niobium ampoules followed by annealing in muffle furnaces. All samples were characterized by X-ray powder diffraction. The structures of four representatives were refined from single-crystal X-ray diffractometer data: ordered Co{sub 2}Al{sub 5} type, P6{sub 3}/mmc, a = 951.2(1), c = 962.9(2) pm, wR = 0.0460, 595 F{sup 2} values, 20 parameters for Er{sub 10}RhCd{sub 3}; a = 945.17(4), c = 943.33(4), wR = 0.0395, 582 F{sup 2} values, 21 parameters for Lu{sub 9.89}PdCd{sub 3.11}; a = 964.16(6), c = 974.93(6) pm, wR = 0.0463, 614 F{sup 2} values, 21 parameters for Y{sub 10}Ir{sub 1.09}Cd{sub 2.91}; a = 955.33(3), c = 974.56(3) pm, wR = 0.0508, 607 F{sup 2} values, 22 refined parameters for Dy{sub 9.92}IrCd{sub 3.08}. Refinements of the occupancy parameters revealed small homogeneity ranges resulting from RE/Cd, respectively T/Cd mixing. The basic building units of the RE{sub 10}TCd{sub 3} phases are transition metal-centered RE{sub 6} trigonal prisms (TP) that are condensed with double-pairs of empty RE{sub 6} octahedra via common triangular faces. A second type of rods is formed by slightly distorted RE3 rate at Cd{sub 6}RE{sub 6} icosahedra which are condensed via Cd{sub 3} triangular faces. The shortest interatomic distances occur for RE-T, compatible with strong covalent bonding interactions. Temperature dependent magnetic susceptibility measurements were performed for RE{sub 10}RhCd{sub 3} (RE = Dy-Tm, Lu), RE{sub 10}IrCd{sub 3} (RE = Er, Tm, Lu) and RE{sub 10}PtCd{sub 3} (RE = Y, Lu). While Y{sub 10}PtCd{sub 3} and Lu{sub 10}TCd{sub 3} (T = Rh, Ir, Pt) show Pauli paramagnetic behavior, the compounds containing paramagnetic rare earth elements show Curie-Weiss behavior (the experimental magnetic moments indicate stable trivalent RE{sup 3+}) and magnetic ordering at low temperatures

Calorimetric investigation of an yttrium-dysprosium spin glass

International Nuclear Information System (INIS)

Wenger, L.E.

1978-01-01

In an effort to compare the spin glass characteristics of yttrium--rare earth alloys with those of the noble-metal spin glasses, the susceptibility and heat capacity of Y/sub 0.98/Dy/sub 0.02/ have been measured in the temperature range 2.5--40 K. The low-field ac susceptibility measurement shows the characteristic cusp-like peak at 7.64 K. The magnetic specific heat of the same sample shows a peak at 7.0 K and may be qualitatively described as a semi-cusp. The magnetic entropy change from absolute zero to 7 K is approximately 0.52 of cR ln(2J+1). These results are qualitatively different than previous calorimetric results on the archetypal spin glasses, AuFe and CuMn, where rounded maxima are observed at temperatures above the spin glass transition temperatures

Rare Earth Garnet Selective Emitter

Science.gov (United States)

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

1994-01-01

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

Rare earth phosphors and phosphor screens

International Nuclear Information System (INIS)

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

1981-01-01

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

Thermal properties of rare earth cobalt oxides and of La1- x Gd x CoO3 solid solutions

Science.gov (United States)

Orlov, Yu. S.; Dudnikov, V. A.; Gorev, M. V.; Vereshchagin, S. N.; Solov'ev, L. A.; Ovchinnikov, S. G.

2016-05-01

Powder X-ray diffraction data for the crystal structure, phase composition, and molar specific heat for La1‒ x Gd x CoO3 cobaltites in the temperature range of 300-1000 K have been analyzed. The behavior of the volume thermal expansion coefficient in cobaltites with isovalent doping in the temperature range of 100-1000 K is studied. It is found that the β( T) curve exhibits two peaks at some doping levels. The rate of the change in the occupation number for the high-spin state of cobalt ions is calculated for the compounds under study taking into account the spin-orbit interaction. With the Birch-Murnaghan equation of state, it is demonstrated that the low-temperature peak in the thermal expansion shifts with the growth of the pressure toward higher temperatures and at pressure P ˜ 7 GPa coincides with the second peak. The similarity in the behavior of the thermal expansion coefficient in the La1- x Gd x CoO3 compounds with the isovalent substitution and the undoped LnCoO3 compound (Ln is a lanthanide) is considered. For the whole series of rare earth cobalt oxides, the nature of two specific features in the temperature dependence of the specific heat and thermal expansion is revealed and their relation to the occupation number for the high-spin state of cobalt ions and to the insulator-metal transition is established.

Separation and Recycling for Rare Earth Elements by Homogeneous Liquid-Liquid Extraction (HoLLE Using a pH-Responsive Fluorine-Based Surfactant

Directory of Open Access Journals (Sweden)

Shotaro Saito

2015-08-01

Full Text Available A selective separation and recycling system for metal ions was developed by homogeneous liquid-liquid extraction (HoLLE using a fluorosurfactant. Sixty-two different elemental ions (e.g., Ag, Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Hg, Ho, In, Ir, La, Lu, Mg, Mn, Mo, Nb, Nd, Ni, Os, P, Pb, Pd, Pr, Pt, Re, Rh, Ru, Sb, Sc, Se, Si, Sm, Sn, Sr, Ta, Tb, Te, Ti, Tl, Tm, V, W, Y, Yb, Zn, and Zr were examined. By changing pH from a neutral or alkaline solution (pH ≥ 6.5 to that of an acidic solution (pH < 4.0, gallium, zirconium, palladium, silver, platinum, and rare earth elements were extracted at >90% efficiency into a sedimented Zonyl FSA® (CF3(CF2n(CH22S(CH22COOH, n = 6–8 liquid phase. Moreover, all rare earth elements were obtained with superior extraction and stripping percentages. In the recycling of rare earth elements, the sedimented phase was maintained using a filter along with a mixed solution of THF and 1 M sodium hydroxide aqueous solution. The Zonyl FSA® was filtrated and the rare earth elements were recovered on the filter as a hydroxide. Furthermore, the filtrated Zonyl FSA was reusable by conditioning the subject pH.

Reconciliation of the excess 176Hf conundrum in meteorites: Recent disturbances of the Lu-Hf and Sm-Nd isotope systematics

Science.gov (United States)

Bast, Rebecca; Scherer, Erik E.; Sprung, Peter; Mezger, Klaus; Fischer-Gödde, Mario; Taetz, Stephan; Böhnke, Mischa; Schmid-Beurmann, Hinrich; Münker, Carsten; Kleine, Thorsten; Srinivasan, Gopalan

2017-09-01

The long-lived 176Lu-176Hf and 147Sm-143Nd radioisotope systems are commonly used chronometers, but when applied to meteorites, they can reveal disturbances. Specifically, Lu-Hf isochrons commonly yield dates up to ∼300 Myr older than the solar system and varying initial 176Hf/177Hf values. We investigated this problem by attempting to construct mineral and whole rock isochrons for eucrites and angrites. Meteorites from different parent bodies exhibit similar disturbance features suggesting that a common process is responsible. Minerals scatter away from isochron regressions for both meteorite classes, with low-Hf phases such as plagioclase and olivine typically being most displaced above (or left of) reference isochrons. Relatively Hf-rich pyroxene is less disturbed but still to the point of steepening Lu-Hf errorchrons. Using our Lu-Hf and Sm-Nd data, we tested various Hf and Lu redistribution scenarios and found that decoupling of Lu/Hf from 176Hf/177Hf must postdate the accumulation of significant radiogenic 176Hf. Therefore early irradiation or diffusion cannot explain the excess 176Hf. Instead, disturbed meteorite isochrons are more likely caused by terrestrial weathering, contamination, or common laboratory procedures. The partial dissolution of phosphate minerals may predominantly remove rare earth elements including Lu, leaving relatively immobile and radiogenic Hf behind. Robust Lu-Hf (and improved Sm-Nd) meteorite geochronology will require the development of chemical or physical methods for removing unsupported radiogenic Hf and silicate-hosted terrestrial contaminants without disturbing parent-daughter ratios.

Effect of rare-earth ion size on local electron structure in RBa2Cu3O7-δ (R = Tm, Dy, Gd, Eu, Nd and Y) superconductors: A positron study

International Nuclear Information System (INIS)

Chen Zhenping; Zhang Jincang; Su Yuling; Xue Yuncai; Cao Shixun

2006-01-01

The effects of rare-earth ionic size on the local electron structure, lattice parameters and superconductivity have been investigated by positron annihilation technique (PAT) and related experiments for RBa 2 Cu 3 O 7-δ (R = Tm, Dy, Gd, Eu, Nd and Y) superconductors. The local electron density n e is evaluated as a function of the rare-earth radius. The results show that both the bulk-lifetime τ B and the defect lifetime τ 2 increase with increasing rare-earth ionic radius, while the local electron density n e decrease with increasing rare-earth ionic radius. These results prove that the changes of n e , the degree of orthorhombic distortion and the coupling between the Cu-O chains and the CuO 2 planes all have an effect on the superconductivity of RBa 2 Cu 3 O 7-δ systems

Neutron diffraction studies on GdB{sub 6} and TbB{sub 6} powders

Energy Technology Data Exchange (ETDEWEB)

Luca, S.E.; Amara, M.; Galera, R.M.; Givord, F.; Granovsky, S.; Isnard, O.; Beneu, B

2004-07-15

We report here the first powder neutron diffraction study of GdB{sub 6} and TbB{sub 6}. GdB{sub 6} and TbB{sub 6} order antiferromagnetically at 15 and 21 K, respectively. In both compounds the transition at T{sub N} is of the first order. Moreover GdB{sub 6} presents a second spontaneous magnetic transition at T{sup *}=8 K. The present study shows that, in both compounds, the magnetic propagation vectors belong to the <((1)/(4)) ((1)/(4)) ((1)/(2))> star and that the direction of the magnetic moment is perpendicular to the ((1)/(2)) component of the wave-vector in GdB{sub 6}, while in TbB{sub 6} the moment is parallel to it. The deduced low-temperature values of the magnetic moments agree with those of the respective rare-earth trivalent ions.

The development of new phosphors of Tb3+/Eu3+ co-doped Gd3Al5O12 with tunable emission

Science.gov (United States)

Teng, Xin; Wang, Wenzhi; Cao, Zhentao; Li, Jinkai; Duan, Guangbin; Liu, Zongming

2017-07-01

The gadolinium aluminum garnets Gd3Al5O12 (GdAG) activated with Tb3+/Eu3+ were successfully prepared via co-precipitation method at 1500 °C in this work. The crystal structure stabilization, elements analysis, microphotograph, PL/PLE spectra, decay behavior and quantum efficiency were discussed in detail. The metastable GdAG compounds been effectively stabilized by doping with smaller 10 at.% Tb3+, which then allows the development of new phosphors of (Gd0.9-xTb0.1Eux)3Al5O12 (GdAG:Tb3+/Eu3+, x = 0-0.03) for opto-functionality explorations. The PLE/PL spectra displays that the strongest PLE peak was located at ∼276 nm, which overlaps the 8S7/2 → 6IJ transition of Gd3+. Under 276 nm excitation, the phosphors exhibited both Tb3+ and Eu3+ emissions at 548 nm (green, 5D4 → 7F5 transition of Tb3+) and 592 nm (orange-red, 5D0 → 7F1 transition of Eu3+), respectively. The emission intensities of Tb3+ and Eu3+ remarkably varied with the Eu3+ incorporation. As a consequence, the emission color can be readily tuned from approximately green to orange-red. Fluorescence decay analysis found that the lifetime for the Tb3+ emission rapidly decreased conforming to the Tb3+ → Eu3+ energy transfer, and the energy transfer efficiency was calculated. Owing to the Gd3+ → Eu3+ and Gd3+ → Tb3+ energy transfer, the emission intensities of Tb3+ and Eu3+ in (Gd0.9-xTb0.1Eux)AG phosphor were higher than (Y0.87Tb0.1Eu0.03)AG and (Lu0.87Tb0.1Eu0.03)AG system. The (Gd0.9-xTb0.1Eux)AG garnet phosphors developed in this work may serve as a new type of phosphor which hopefully meets the requirements of various lighting and optical display applications.

Raman and infrared spectroscopy of pure and doped GdAlO3 with rare earth ions

International Nuclear Information System (INIS)

Bagnato, V.S.

1983-01-01

IR and Raman measurements were carried out in pure and Eu +3 - doped GdAlO 3 with the purpose of understanding their K=O phonom modes and the Eu +3 electronic transitions. Starting from the GdAlO 3 symmetry, (D1 6 sub(2h)), the correlation method allows the classification of the number and symmetries of the modes, as well their assignement as either internal or external. Experimental and theoretical results are in good agreement and show three well defined absorption bands in GdAlO 3 . The internal modes are found to be located around 670 cm -1 (stretching) and 480 cm -1 (bending), while the external modes are around 200 cm -1 . The interaction of Eu +3 electronic states with the GdAlO 3 crystal field were studied by taking into account a small perturbative orthorrombic (C sub(s)) distortion on a crystal field with symmetry O sub(h). This small distortion lifts completely the degeneracy of the 7 F sub(J) (J=0,1,...,6) levels and allows the 7 J sub(o) → 7 F sub(J) transitions. (Author) [pt

The Gd{sub 14}Ag{sub 51} structure type and its relation to some complex amalgam structures

Energy Technology Data Exchange (ETDEWEB)

Tambornino, Frank; Sappl, Jonathan; Hoch, Constantin, E-mail: constantin.hoch@cup.uni-muenchen.de

2015-01-05

Highlights: • The Gd{sub 14}Ag{sub 51} structure type has been revisited on the basis of single crystal diffraction data. • Symmetry analysis from electron density and TEM shows the space group P6/m to be true. • Gd{sub 14}Ag{sub 51} shows good metallic behaviour. • Structure relations to alkali, alkaline-earth and rare-earth metal amalgams can be established. • Complexity values for the RE{sub 14}Ag{sub 51} structure family were calculated. - Abstract: A plethora of binary and ternary intermetallic compounds has been assigned to the Gd{sub 14}Ag{sub 51} structure type, crystallising in the hexagonal system (space group P6/m, a = 1264.30(18) pm, c = 933.58(11) pm for Gd{sub 14}Ag{sub 51}). Starting in the late 1960s, much work has been invested in the structural elucidation of these crystal structures. However, reliable single crystal data are scarce, and most structure type assignments have been performed merely on the basis of powder data. We have redetermined four representatives of the binary RE{sub 14}Ag{sub 51} structure type (RE = Y, Ce, Gd, Tb) with modern high-precision single crystal X-ray methods. The assignment of the Gd{sub 14}Ag{sub 51} structure type to space group P6/m was additionally verified by careful analysis of high resolution transmission electron micrographs. We emphasise the close relation of the Gd{sub 14}Ag{sub 51} structure type to the structures of some recently described amalgams of similar composition focussing on disorder phenomena and structural complexity. Furthermore, we provide detailed information on synthesis as well as electrical and magnetic properties for Gd{sub 14}Ag{sub 51}, the parent compound of this structure family.

Growth of multiferroic Gd1-xYxMnO3 single crystals by optical floating zone technique

International Nuclear Information System (INIS)

Sarguna, R.M.; Ganesamoorthy, S.; Sridharan, V.; Subramanian, N.

2014-01-01

Rare earth manganites RMnO 3 with distorted perovskite structure are excellent multiferroic materials. The discovery of magnetic spin driven ferroelectricity in orthorhombic manganites (TbMnO 3 ) has sparked a surge in research into understanding the fundamental mechanism of multiferroic behavior. These systems fall under the category of type-2 multiferroics, the change of spatially modulated magnetic moment from sinusoidal to cycloidal gives rise to electric polarization. The magnetic structure depends upon the Mn-O-Mn bond angle. GdMnO 3 shows multiferroic properties only in the presence of applied magnetic field. When a magnetic field is applied along the b-axis, GdMnO 3 enters a ferroelectric state with an electric polarisation along the c-axis. By altering the Mn-O-Mn angle it is expected that GdMnO 3 will show multiferroic property even in the absence of magnetic field like TbMnO 3 . To alter the Mn-O-Mn bond angle GdMnO 3 was substituted with Y having lower ionic radius at Gd site. The effect of Y doping at the rare-earth site in GdMnO 3 investigated on polycrystalline samples of Gd 1-x Y x MnO 3 demonstrated a magneto-electric coupling in x=0.1-0.4. Single crystals are expected to give much amplified signal in respect of ferroelectric and magnetic properties. In this work we have grown Y substituted Gd 1-x Y x MnO 3 (x = 0.2, 0.3 and 0.4) by optical floating zone technique under different gas atmosphere. Growth rate of 1-2 mm/h yielded crack free crystals. Quality of the crystals was checked using Laue diffraction. Effect of growth rate and atmosphere pressure will be presented in this talk. (author)

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

Energy Technology Data Exchange (ETDEWEB)

Hackbarth, Liisa

2015-11-24

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

Thermal decomposition of yttrium(III) propionate and butyrate

DEFF Research Database (Denmark)

Grivel, Jean-Claude

2013-01-01

The thermal decompositions of yttrium(III) propionate monohydrate (Y(C2H5CO2)3·H2O) and yttrium(III) butyrate dihydrate (Y(C3H7CO2)3·2H2O) were studied in argon by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction and hot-stage microscopy. These two...

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

Science.gov (United States)

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 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.

Temperature effects on separation of Gd3+ from Gd-DTPA-folate using nanofiltration method

Science.gov (United States)

Rahayu, I.; Indraneli, R. P.; Yuliyati, Y. B.; Anggraeni, A.; Soedjanaatmadja, U. M. S.; Bahti, H. H.

2018-05-01

MRI is one of the best techniques in medical diagnostics. Contrast agents are used to improve the visual of organs that are difficult to distinguish through MRI. Gd-DTPA-folate is one of the specific contrast agents against cancer diagnosis, because it has a high affinity to folate receptors. In the complexing Gd-DTPA-folate, does not rule out the complexity step runs imperfectly, so there is still Gd3+ in the Gd-DTPA-folate complex. The separation of Gd3+ from the Gd-DTPA-folate complex is important to eliminate toxic effects on the contrast agent. This study aims to determine the effect of temperature on the separation of Gd-DTPA-folate from Gd3+ with nanofiltration. The method are preparation Gd-DTPA-folate from GdCl3.6H2O and DTPA-folate by reflux method, then separated Gd-DTPA-folate complex from Gd3+ with nanofiltration at variation temperature (40, 41, 42, 43, 44oC ). Then, the values of flux and rejection coefficients were analyzed. The results showed that the optimum temperature for the separation of Gd3+ from Gd-DTPA-folate was achieved at 42.6°C with the rejection coefficient of 24% and the permeate flux of 403 L.m-2.h-1.

Luminescent determination of trace amounts of terbium using diantipyrylmethane and salicylic acid

Energy Technology Data Exchange (ETDEWEB)

Tishchenko, M A; Gerasimenko, G I; Poluehktov, N S [AN Ukrainskoj SSR, Odessa. Inst. Obshchej i Neorganicheskoj Khimii

1978-01-01

To elucidate the possibility of using pyrazolone-5-diantipyril-methane (DAM) derivative for determination of terbium microimpurities, the conditions have been studied of luminescent determination of terbium in complex compounds containing an ion of rare-earth element, diantipyrilmethane, and salicylic acid (Sal.). The ratio between the components in the complex REE-DAM-Sal is 1:1:3. La, Y, Gd do not affect the luminescence intensity of terbium complex. A luminescent method of determining terbium traces in highly pure oxides of lanthanum, gadolinium, lutetium, and yttrium has been developed in which suspensions of complex precipitation are used. The amount of terbium determined in oxide of lanthanum, gadolinium, and lutetium is (1-5)x10/sup -6/% and (2-3)x10/sup -5/% in yttrium oxide.

Recovery of rare earths from red mud

International Nuclear Information System (INIS)

Bautista, R.G.

1992-01-01

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

High magnetic field study of HoBaCo2O5.5 and GdBaCo2O5.5 layered cobaltites: the effect of rare-earth size

International Nuclear Information System (INIS)

Frontera, C.; Respaud, M.; Garcia-Munoz, J.L.; Llobet, A.; Carrillo, A.E.; Caneiro, A.; Broto, J.M.

2004-01-01

By means of high-pulsed magnetic field up to μ 0 H=32 T we have studied HoBaCo 2 O 5+δ (δ=0.52(1)). The high-field M(H) integrated curves evidence a magnetic field-induced phase transition visible from about T=75 to 275 K. The obtained results are compared with the field-induced transition found for GdBaCo 2 O 5+δ (with δ=0.54(2)). The jump of the magnetization at the field-induced transition is independent of the rare earth at this level of oxygen content. In contrast, we have observed larger values of the critical field, and that the transition persists up to higher temperature, when reducing the rare-earth size. This indicates that the low-temperature antiferromagnetic phase becomes more stable when the size of the rare earth is reduced

Time domain simulation of Gd3+-Gd3+ distance measurements by EPR

Science.gov (United States)

Manukovsky, Nurit; Feintuch, Akiva; Kuprov, Ilya; Goldfarb, Daniella

2017-07-01

Gd3+-based spin labels are useful as an alternative to nitroxides for intramolecular distance measurements at high fields in biological systems. However, double electron-electron resonance (DEER) measurements using model Gd3+ complexes featured a low modulation depth and an unexpected broadening of the distance distribution for short Gd3+-Gd3+ distances, when analysed using the software designed for S = 1/2 pairs. It appears that these effects result from the different spectroscopic characteristics of Gd3+—the high spin, the zero field splitting (ZFS), and the flip-flop terms in the dipolar Hamiltonian that are often ignored for spin-1/2 systems. An understanding of the factors affecting the modulation frequency and amplitude is essential for the correct analysis of Gd3+-Gd3+ DEER data and for the educated choice of experimental settings, such as Gd3+ spin label type and the pulse parameters. This work uses time-domain simulations of Gd3+-Gd3+ DEER by explicit density matrix propagation to elucidate the factors shaping Gd3+ DEER traces. The simulations show that mixing between the |+½, -½> and |-½, +½> states of the two spins, caused by the flip-flop term in the dipolar Hamiltonian, leads to dampening of the dipolar modulation. This effect may be mitigated by a large ZFS or by pulse frequency settings allowing for a decreased contribution of the central transition and the one adjacent to it. The simulations reproduce both the experimental line shapes of the Fourier-transforms of the DEER time domain traces and the trends in the behaviour of the modulation depth, thus enabling a more systematic design and analysis of Gd3+ DEER experiments.

Air stability and magnetic properties of GdN, TiN, and (Gd,Ti)N nanoparticles

International Nuclear Information System (INIS)

Si Pingzhan; Choi, C. J.; Tegus, O.; Brueck, E.; Geng, D. Y.; Zhang, Z. D.

2008-01-01

GdN, TiN, and (Gd,Ti)N nanoparticles were prepared by arc evaporating Gd, Ti, and Gd-Ti alloys in N 2 , respectively. Most of these nanoparticles show narrow size distribution with average diameter of 20 nm. Shell/core structure was observed in the (Gd,Ti)N nanoparticles, in which the shell was formed by surface reaction with air. (Gd,Ti)N nanoparticles are more stable than GdN nanoparticles in air due partially to the formation of the protective shell. The Curie temperature of GdN nanoparticles is lower than that of the bulk GdN. Both GdN and (Gd, Ti)N nanoparticles are difficult to reach magnetic saturation and show zero coercivity

A thermal neutron scattering law for yttrium hydride

Science.gov (United States)

Zerkle, Michael; Holmes, Jesse

2017-09-01

Yttrium hydride (YH2) is of interest as a high temperature moderator material because of its superior ability to retain hydrogen at elevated temperatures. Thermal neutron scattering laws for hydrogen bound in yttrium hydride (H-YH2) and yttrium bound in yttrium hydride (Y-YH2) prepared using the ab initio approach are presented. Density functional theory, incorporating the generalized gradient approximation (GGA) for the exchange-correlation energy, is used to simulate the face-centered cubic structure of YH2 and calculate the interatomic Hellmann-Feynman forces for a 2 × 2 × 2 supercell containing 96 atoms. Lattice dynamics calculations using PHONON are then used to determine the phonon dispersion relations and density of states. The calculated phonon density of states for H and Y in YH2 are used to prepare H-YH2 and Y-YH2 thermal scattering laws using the LEAPR module of NJOY2012. Analysis of the resulting integral and differential scattering cross sections demonstrates adequate resolution of the S(α,β) function. Comparison of experimental lattice constant, heat capacity, inelastic neutron scattering spectra and total scattering cross section measurements to calculated values are used to validate the thermal scattering laws.

Late night activity regarding stroke codes: LuNAR strokes.

Science.gov (United States)

Tafreshi, Gilda; Raman, Rema; Ernstrom, Karin; Rapp, Karen; Meyer, Brett C

2012-08-01

There is diurnal variation for cardiac arrest and sudden cardiac death. Stroke may show a similar pattern. We assessed whether strokes presenting during a particular time of day or night are more likely of vascular etiology. To compare emergency department stroke codes arriving between 22:00 and 8:00 hours (LuNAR strokes) vs. others (n-LuNAR strokes). The purpose was to determine if late night strokes are more likely to be true strokes or warrant acute tissue plasminogen activator evaluations. We reviewed prospectively collected cases in the University of California, San Diego Stroke Team database gathered over a four-year period. Stroke codes at six emergency departments were classified based on arrival time. Those arriving between 22:00 and 8:00 hours were classified as LuNAR stroke codes, the remainder were classified as 'n-LuNAR'. Patients were further classified as intracerebral hemorrhage, acute ischemic stroke not receiving tissue plasminogen activator, acute ischemic stroke receiving tissue plasminogen activator, transient ischemic attack, and nonstroke. Categorical outcomes were compared using Fisher's Exact test. Continuous outcomes were compared using Wilcoxon's Rank-sum test. A total of 1607 patients were included in our study, of which, 299 (19%) were LuNAR code strokes. The overall median NIHSS was five, higher in the LuNAR group (n-LuNAR 5, LuNAR 7; P=0·022). There was no overall differences in patient diagnoses between LuNAR and n-LuNAR strokes (P=0·169) or diagnosis of acute ischemic stroke receiving tissue plasminogen activator (n-LuNAR 191 (14·6%), LuNAR 42 (14·0%); P=0·86). Mean arrival to computed tomography scan time was longer during LuNAR hours (n-LuNAR 54·9±76·3 min, LuNAR 62·5±87·7 min; P=0·027). There was no significant difference in 90-day mortality (n-LuNAR 15·0%, LuNAR 13·2%; P=0·45). Our stroke center experience showed no difference in diagnosis of acute ischemic stroke between day and night stroke codes. This

Adhesive activity of Lu glycoproteins is regulated by interaction with spectrin

Energy Technology Data Exchange (ETDEWEB)

An, Xiuli; Gauthier, Emilie; Zhang, Xihui; Guo, Xinhua; Anstee, David; Mohandas, Narla; Anne Chasis, Joel

2008-03-18

The Lutheran (Lu) and Lu(v13) blood group glycoproteins function as receptors for extracellular matrix laminins. Lu and Lu(v13) are linked to the erythrocyte cytoskeleton through a direct interaction with spectrin. However, neither the molecular basis of the interaction nor its functional consequences have previously been delineated. In the present study, we defined the binding motifs of Lu and Lu(v13) on spectrin and identified a functional role for this interaction. We found that the cytoplasmic domains of both Lu and Lu(v13) bound to repeat 4 of the spectrin chain. The interaction of full-length spectrin dimer to Lu and Lu(v13) was inhibited by repeat 4 of {alpha}-spectrin. Further, resealing of this repeat peptide into erythrocytes led to weakened Lu-cytoskeleton interaction as demonstrated by increased detergent extractability of Lu. Importantly, disruption of the Lu-spectrin linkage was accompanied by enhanced cell adhesion to laminin. We conclude that the interaction of the Lu cytoplasmic tail with the cytoskeleton regulates its adhesive receptor function.

Study of the production of {sup 177}Lu through {sup 176}Yb (n, {gamma}) {sup 177}Yb {yields} {sup 177}Lu nuclear reaction

Energy Technology Data Exchange (ETDEWEB)

Silva, Giovana Pasqualini da; Osso Junior, Joao Alberto [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mail: gpsilva@ipen.br; jaosso@ipen.br

2007-07-01

The beta minus emitter {sup 177}Lu is a promising therapeutic radioisotope for the curative treatment of cancer using labelled proteins. It has a half - life of T{sub 1/2} = 6.71 day and maximum and average {beta}{sup -} energies of 421 and 133 keV, resulting in a short range of radiation in tissue. The decay is accompanied by the emission of low energy {gamma}-radiation with 208.3 keV (11%) and 113 keV (6.4%) suitable for simultaneous imaging, {sup 177}Lu can be produced by two different routes, namely, by irradiation of natural Lu{sub 2}O{sub 3} target ({sup 176}Lu, 2.6%) or enriched (in {sup 176}Lu) Lu{sub 2}O{sub 3} target, as also by irradiation of Yb target (Yb{sub 2}O{sub 3}) followed by radiochemical separation of {sup 177}Lu from Yb isotopes. The objective of this work is to study the production of {sup 177}Lu through the indirect {sup 176}Yb(n,{gamma}){sup 177}Yb {yields} {sup 177}Lu nuclear reaction. The results of the production yield of {sup 177}Lu will be shown and compared with the direct reaction. The method of choice for the chemical separation between Lu and Yb was the ion exchange, using an cation exchange resin in Cl{sup -} form and {alpha}-HIBA as eluent. Preliminary results showed a good separation of {sup 177}Lu from Yb{sub 2}O{sub 3} indirect targets. (author)

Photoluminescence related to Gd3+:N-vacancy complex in GaN:Gd multi-quantum wells

International Nuclear Information System (INIS)

Almokhtar, Mohamed; Emura, Shuichi; Koide, Akihiro; Fujikawa, Takashi; Asahi, Hajime

2015-01-01

Highlights: • We grew Gd-doped GaN multi-quantum wells (MQWs) with quantum layer thickness of one nm by MBE. • The X-ray absorption near edge structure spectra observed at Gd LIII-edge indicate a nitrogen vacancy adjacent to Gd substituting the Ga ion in Gd-doped GaN MQW. • The photoluminescence of the samples is discussed considering the formation of a Gd 3+ :Nitrogen-vacancy complex. • A model is presented considering exciton-polaron formation trapped in defect sites around the Gd 3+ :N-vacancy complex in Gd-doped GaN MQWs. - Abstract: The photoluminescence of Gd-doped GaN multi-quantum wells (MQWs) is presented and discussed considering the formation of a Gd 3+ :Nitrogen-vacancy (N-vacancy) complex. A lower energy photoluminescence peak was observed for the Gd-doped GaN MQW sample with respect to the main peak assigned to a neutral donor bound exciton (D 0 X) of the undoped GaN MQW sample. The X-ray absorption near edge structure spectrum observed at Gd L III -edge indicates a nitrogen vacancy adjacent to the Gd substituting the Ga ion in Gd-doped GaN MQW sample. Local stresses around the Gd dopants in Gd-doped GaN matrix generated due to the larger diameter of the Gd 3+ ion with respect to the Ga 3+ ion can be relieved by the creation of vacancies. The lower formation energy of N-vacancies in GaN matrix introduce them as a preferred candidate to relieve the generated stresses. A Gd 3+ :N-vacancy complex consisting of a Gd 3+ ion and the created nitrogen vacancy adjacent to the Gd 3+ dopant is likely to form in GaN:Gd matrix. The lower photoluminescence peak energy observed in the Gd-doped GaN MQW sample is assigned to the recombination of an exciton captured at the Gd 3+ :N-vacancy complex forming a small polaron-like state. A model is presented considering the small exciton-polaron population in defect sites captured around the Gd 3+ ions in the Gd-doped GaN

Development of 2024 AA-Yttrium composites by Spark Plasma Sintering

Science.gov (United States)

Vidyasagar, CH S.; Karunakar, D. B.

2018-04-01

The method of fabrication of MMNCs is quite a challenge, which includes advanced processing techniques like Spark Plasma Sintering (SPS), etc. The objective of the present work is to fabricate aluminium based MMNCs with the addition of small amounts of yttrium using Spark Plasma Sintering and to evaluate their mechanical and microstructure properties. Samples of 2024 AA with yttrium ranging from 0.1% to 0.5 wt% are fabricated by Spark Plasma Sintering (SPS). Hardness of the samples is determined using Vickers hardness testing machine. The metallurgical characterization of the samples is evaluated by Optical Microscopy (OM), Field Emission Scanning Electron Microscopy (FE-SEM). Unreinforced 2024 AA sample is also fabricated as a benchmark to compare its properties with those of the composite developed. It is found that the yttrium addition increases the above mentioned properties by altering the precipitation kinetics and intermetallic formation to some extent and then decreases gradually when yttrium wt% increases beyond 0.3 wt%. High density (˂ 99.75) is achieved in the samples and highest hardness achieved is 114 Hv, fabricated by spark plasma sintering and uniform distribution of yttrium is observed.

Kinetics of electrophilic exchange of lanthanide(3) and copper(2) ions in aqueous solutions of ethylenediaminetetraacetates. [Rare earths: La,Pr,Nd,Eu,Gd,Tb,Er,Yb

Energy Technology Data Exchange (ETDEWEB)

Nikitenko, S.I.; Martynenko, L.I.; Pechurova, N.I.; Spitsyn, V.I. (Moskovskij Gosudarstvennyj Univ. (USSR))

1984-05-01

Electrophilic exchange in the MA/sup -/ - Cu/sup 2 +/ (M/sup 3 +/=La/sup 3 +/, PUPSILON/sup 3 +/, Nd/sup 3 +/, Eu/sup 3 +/, Gd/sup 3 +/, Tb/sup 3 +/, Er/sup 3 +/, Yb/sup 3 +/, A/sup 4 -/=ethylenediaminetetraacetate) systems is studied. Copper is chosen as a constituent cation, because the stability of the CuA/sup 2 +/- complex is higher than that of the MA/sup -/ complex, besides the CuA/sup 2 -/, is characterized by a high extinction coefficient E/sub 280/=3200. Electrophilic exchange in the systems is shown to be realized through the acid dissociation mechanism and through the association mechanism. Consideration of the acid dissociation mechanism assumes that the exchange is limited by a break in the metal-oxygen bond in the intermediate protonated complex. In case of the association mechanism it is limited by a break in the metal-nitrogen bond in the intermediate binuclear complex. Rate constants of the limiting stage are calculated. Dependences of the rate constants of exchange on the stability of the complexes, the order number of the element, acidity of medium, Cu/sup 2 +/ concentration are given. Differences are shown to exist between the exchange mechanisms in the studied: systems for the REE of cerium and yttrium subgroups.

Comparison of Spectral and Scintillation Properties of LuAP:Ce and LuAP:Ce,Sc Single Crystals

Science.gov (United States)

Petrosyan, Ashot G.; Derdzyan, Marina; Ovanesyan, Karine; Shirinyan, Grigori; Lecoq, Paul; Auffray, Etiennette; Kronberger, Matthias; Frisch, Benjamin; Pedrini, Christian; Dujardin, Christophe

2009-10-01

Scintillation properties of LuAP:Ce and LuAP:Ce,Sc crystal series were studied under excitation by gamma-rays from a 137Cs source. Both series demonstrated comparable optical quality in terms of underlying absorption at 260 nm, slope of the optical edge and transmission in the range of emission. The light yield of LuAP:Ce crystals measured in 0.2 cm times 0.2 cm times 0.8 cm pixels increases linearly with the Ce concentration reaching at 0.58 at. % 6448 plusmn 322 ph/MeV and 9911 plusmn 496 ph/MeV in the long and in the short directions respectively (the light yield ratio is 65%) and shows no sign of light saturation. The energy resolution is found to depend, among other factors, on the uniformity of Ce concentration within the pixels and is improved to 7.1 plusmn 0.4% (I = 0.2 cm), 9.5 plusmn 0.5% (I = 0.8 cm). Intentional co-doping with Sc + ions was tested and resulted in increase of the Ce distribution coefficient to about 0.3. This enabled to increase the concentration of Ce in LuAP:Ce,Sc crystals up to 0.7 at. %, while conserving high optical quality. In contrast to LuAP:Ce, the light yield in LuAP:Ce,Sc crystals does not increase with Ce concentration, the photo peak being gradually suppressed. The involved mechanisms are discussed basing on measurements of the unit cell volumes, Ce concentration uniformity, x-ray rocking spectra, absorption spectra of pure and variously doped LuAP crystals, and emission spectra under different excitations.

Strain-Induced Ferromagnetism in Antiferromagnetic LuMnO3 Thin Films

Science.gov (United States)

White, J. S.; Bator, M.; Hu, Y.; Luetkens, H.; Stahn, J.; Capelli, S.; Das, S.; Döbeli, M.; Lippert, Th.; Malik, V. K.; Martynczuk, J.; Wokaun, A.; Kenzelmann, M.; Niedermayer, Ch.; Schneider, C. W.

2013-07-01

Single phase and strained LuMnO3 thin films are discovered to display coexisting ferromagnetic and antiferromagnetic orders. A large moment ferromagnetism (≈1μB), which is absent in bulk samples, is shown to display a magnetic moment distribution that is peaked at the highly strained substrate-film interface. We further show that the strain-induced ferromagnetism and the antiferromagnetic order are coupled via an exchange field, therefore demonstrating strained rare-earth manganite thin films as promising candidate systems for new multifunctional devices.

NMR measurements in milled GdCo2 and GdFe2 intermetallic compounds

International Nuclear Information System (INIS)

Tribuzy, C.V.B.; Guimaraes, A.P.; Biondo, A.; Larica, C.; Alves, K.M.B.

1998-12-01

We have used the nuclear magnetic resonance technique to study the magnetic and structural properties of the Gd-Co and Gd-Fe metallic systems, starting with the C15 laves phase intermetallic compounds, and submitting them to a high energy milling process. This leads to the amorphization of the samples, as determined by the X-ray diffraction spectra. For the Gd-Co system the NMR study used the 59 Co nucleus; in the Gd-Fe system, 155,157 Gd and 57 Fe were used. Both systems showed segregation of the pure elements, after a few hours of milling. In the Gd-Co system, a single line, of increasing width, was observed in the 59 Co spectrum. In the Gd-Fe system, the 155 Gd and 157 Gd resonances show three lines, arising from electrical quadrupole interaction. With increasing milling time, the lines broaden, and extra lines appear attributed to a cubic phase of Gd; this interpretation is supported by the X-ray analysis of the samples. The 57 Fe NMR spectrum of this system also informs on the direction of magnetization of the samples in the early stages of milling. From 1 h to 7 h of milling, a spectrum of α-Fe was observed. The study of the NMR line intensity as a function of radio frequency (r.f.) power in Gd Co 2 suggests the existence of regions of the samples with different degrees of disorder. We have observed the persistence of NMR signals from the original intermetallic compounds in the samples with up to 10 h and 7 h of milling, respectively, for Gd Co 2 and Gd Fe 2 . (author)

Production and Quality Control of 177Lu-Dotatate [177Lu-dota- try3]-Octreotate: Clinical Application

International Nuclear Information System (INIS)

Barboza, M.F. de; Herrerias, R.; Souza, A.A. de; Pereira, G.; Pires, J.A.; Fukumori, N.T.O.; Matsuda, M.M.N.; Almeida, E.V.; Mengatti, J.; Belfer, A.J.; Hilario, L.N.

2009-01-01

Introduction: Somatostatin receptors have been identified in different kinds of tumors such as neuroendocrine tumors and tumors of the central nervous system, breast, lung and lymphatic tissue making these receptors potential targets for radionuclide diagnostics and therapy. These observations have served as the biomolecular basis for the clinical use of radiolabeled somatostatin analogues which, at present, are of great interest in nuclear medicine for diagnostic and peptide receptor radionuclide therapy (PRRT) applications. There are only a few treatment modalities for metastasized neuroendocrine gastroenteropancreatic (GEP) tumors. Besides surgery, (chemo)-embolization, chemotherapy, and treatment with somatostatin (SST) analogs, peptide receptor radionuclide therapy (PRRT) offers therapeutic strategy, as the majority of GEP tumors possess somatostatin receptors (SSTRs). Somatostatin analogs featuring a DOTA-chelator can be radiolabeled with the β-emitters radioisotopes, Yttrium-90 ( 90 Y) and Lutetium-177 ( 177 Lu) for PRRT. Analogs frequently used for therapy are: [DOTA-Tyr 3 ]-octreotide and [DOTA-Tyr 3 ]octreotate. In the latter compound, the alcohol threoninol at the C-terminal of the octreotide has been replaced by the natural threonin amino acid. This alteration resulted in an analog: (Tyr 3 -octreotate), which showed increased affinity for sst2, compared to both [Tyr 3 ]-octreotide and [Phe 1 ]octreotide 'in-vitro' and 'in-vivo'. Clinical studies in patients with different SST-positives tumors proved advantages of [ 177 Lu- DOTA-Tr 3 ]-octreate for therapy. PRRT with radiolabeled somatostatin analogs was shown to be effective in patients with SST2-positive-size reduction, improving quality of life and survival. Objective: The aim of this work was to present the production and the quality control of 177 Lu-Tyr 3 ---octreotate, using DOTA (1,4,7,10-tetrazacyclododecane-N,N',N',N''-tetra acetic acid) as chelating agent at the Radiopharmacy Directory, IPEN

Sol gel synthesis for preparation of yttrium aluminium garnet

NARCIS (Netherlands)

Vrolijk, J.W.G.A.; Willems, J.W.M.M.; Metselaar, R.; With, de G.; Terpstra, R.A.; Metselaar, R.

1989-01-01

Sol-gel—synthesis for preparation of pure yttrium aluminium garnet powder with small grain size is subject of this ongoing study. Starting materials were sulfates and chlorides of yttrium and aluminium. To obtain pure YAG (Y3A1SO1Z) pH during hydrolysis as well as temperature during calcination and

High spin K isomeric target of 177mLu

International Nuclear Information System (INIS)

Roig, O.; Belier, G.; Daugas, J.-M.; Delbourgo, P.; Maunoury, L.; Meot, V.; Morichon, E.; Sauvestre, J.-E.; Aupiais, J.; Boulin, Y.; Fioni, G.; Letourneau, A.; Marie, F.; Ridikas, D.

2004-01-01

The techniques used to produce a 177m Lu (J π =23/2 - ,T 1/2 =160.4 days) target are described in this paper. Firstly, an isotopic separation of an enriched lutetium sample was used to reach a purity of 176 Lu close to 99.993%. Afterwards, the high neutron flux of the Grenoble Institut Laue-Langevin reactor was used to produce the 177m Lu isomer by the 176 Lu(n,γ) reaction. Finally, a chemical separation was performed to extract 10 13 nuclei of 177m Lu. Thanks to this experiment, we have been able to estimate the destruction cross-section of the 177m Lu

Lutetium oxide-based transparent ceramic scintillators

Science.gov (United States)

Seeley, Zachary; Cherepy, Nerine; Kuntz, Joshua; Payne, Stephen A.

2016-01-19

In one embodiment, a transparent ceramic of sintered nanoparticles includes gadolinium lutetium oxide doped with europium having a chemical composition (Lu.sub.1-xGd.sub.x).sub.2-YEu.sub.YO.sub.3, where X is any value within a range from about 0.05 to about 0.45 and Y is any value within a range from about 0.01 to about 0.2, and where the transparent ceramic exhibits a transparency characterized by a scatter coefficient of less than about 10%/cm. In another embodiment, a transparent ceramic scintillator of sintered nanoparticles, includes a body of sintered nanoparticles including gadolinium lutetium oxide doped with a rare earth activator (RE) having a chemical composition (Lu.sub.1-xGd.sub.x).sub.2-YRE.sub.YO.sub.3, where RE is selected from the group consisting of: Sm, Eu, Tb, and Dy, where the transparent ceramic exhibits a transparency characterized by a scatter coefficient of less than about 10%/cm.

Spectroscopic characterization and temporal dynamics of energy transfer process between Tm3+ -Ho3+ and Yb3+ -Tm3+ ions in LiYF4 and LiLuF4 crystals

International Nuclear Information System (INIS)

Tarelho, Luiz Vicente Gomes

2001-01-01

In this work, we perform spectroscopic studies to characterize the energy transfer processes occurring in rare-earth doped lithium fluoride systems, aiming the optimization of the population inversion of these media. Yb 3+ ion was used in order to probe the electron-phonon coupling in LiYF 4 , LiGdF 4 and LiLuF 4 matrices. In these systems it was obtained the average phononenergy, the vibronic transition probability and Huang-Rhys coupling constant. These parameters are dependent on the crystal host and the LiLuF 4 system presents excluded correlation effects, an electronic repulsion that weakens the vibronic coupling. The Tm:Ho:LiYF 4 system was studied under diode laser pumping at 796 nm, aiming the 2 μm emission optimization. The ideal conditions of concentration and laser power were determined favouring the latter emission. Upconversion processes of two photons were identified besides the energy transfer among ions. The dynamic processes of luminescence of donors and acceptors allowed one to classify the energy transfer process as an energy transfer process assisted by fast diffusion among donors. The spectroscopic study of the Yb:Tm:LiYF 4 allowed the determination of efficient non resonant transfer mechanisms between ( 2 F 5/2 ) Ytterbium level and ( 3 H 5 ) Thulium level, assisted by two phonon with hopping migration among donors ( Foerster-Burshtein model). The repopulation process of the Yb donor level is due to a cooperative sensitization between Yb-Tm pairs followed by an energy transfer process. (author)

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

Science.gov (United States)

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.

Preparation and studies of Eu3+ and Tb3+ co-doped Gd2O3 and Y2O3 sol-gel scintillating films

International Nuclear Information System (INIS)

Morales Ramirez, A. de J; Garcia Murillo, A.; Carrillo Romo, F. de J; Ramirez Salgado, J.; Le Luyer, C.; Chadeyron, G.; Boyer, D.; Moreno Palmerin, J.

2009-01-01

Eu 3+ (2.5 at.%) and Tb 3+ (0.005-0.01 at.%) co-doped gadolinium and yttrium oxide (Gd 2 O 3 and Y 2 O 3 ) powders and films have been prepared using the sol-gel process. High density and optical quality thin films were prepared with the dip-coating technique. Gadolinium (III) 2,4-pentadionate and yttrium (III) 2,4-pentadionate were used as precursors, and europium and terbium in their nitrate forms were used as doping agents. Chemical and structural analyses (infrared spectroscopy, X-ray diffraction and high-resolution transmission electron microscopy) were conducted on both sol-gel precursor powders and dip-coated films. The morphology of thin films heat-treated at 700 o C was studied by means of atomic force microscopy. It was shown that the highly dense and very smooth films had a root mean roughness (RMS) of 2 nm ± 0.2 (A = 0.0075 Tb 3+ ) and 24 nm ± 3.0 (B = 0.01 Tb 3+ ). After treatment at 700 o C, the crystallized films were in the cubic phase and presented a polycrystalline structure made up of randomly oriented crystallites with grain sizes varying from 20 to 60 nm. The X-ray induced emission spectra of Eu 3+ - and Tb 3+ -doped Gd 2 O 3 and Y 2 O 3 powders showed that Tb 3+ contents of 0.005, 0.0075 and 0.01 at.% affected their optical properties. Lower Tb 3+ concentrations (down to 0.005 at.%) in both systems enhanced the light yield.

Efficiency of Lu2SiO5:Ce (LSO) powder phosphor as X-ray to light converter under mammographic imaging conditions

International Nuclear Information System (INIS)

David, S.; Michail, C.; Valais, I.; Nikolopoulos, D.; Liaparinos, P.; Kalivas, N.; Kalatzis, I.; Toutountzis, A.; Efthimiou, N.; Loudos, G.; Sianoudis, I.; Cavouras, D.; Dimitropoulos, N.; Nomicos, C.D.; Kandarakis, I.; Panayiotakis, G.S.

2007-01-01

The aim of the present study was to examine the light emission efficiency of Lu 2 SiO 5 :Ce (LSO) powder scintillator under X-ray mammographic imaging conditions. Powder LSO scintillator has never been used in X-ray imaging. For the purposes of the present study, a 25 mg/cm 2 thick scintillating screen was prepared in our laboratory, by sedimentation of Lu 2 SiO 5 :Ce powder. Absolute luminescence efficiency measurements were performed within the range of X-ray tube voltages (22-49 kVp) used in mammographic applications. Parameters related to X-ray detection, i.e. the energy absorption efficiency (EAE) and the quantum detection efficiency (QDE) were calculated. A theoretical model, describing radiation and light transfer, was employed to fit experimental data and to estimate values of the intrinsic conversion efficiency and the light attenuation coefficients of the screen. The spectral compatibility of the LSO powder scintillator to mammographic X-ray films and to various electronic optical detectors was determined by performing light emission spectrum measurements and by taking into account the spectral sensitivity of the optical detectors. Results in the voltage range used in mammography showed that Lu 2 SiO 5 :Ce powder scintillator has approximately 10% higher values of QDE and 4.5% higher values of EAE than Gd 2 O 2 S:Tb

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

Energy Technology Data Exchange (ETDEWEB)

Radu, I.E.

2006-03-15

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

High pressure Raman scattering study on the phase stability of LuVO4

International Nuclear Information System (INIS)

Rao, Rekha; Garg, Alka B.; Sakuntala, T.; Achary, S.N.; Tyagi, A.K.

2009-01-01

High pressure Raman spectroscopic investigations have been carried out on rare earth orthovanadate LuVO 4 upto 26 GPa. Changes in the Raman spectrum around 8 GPa across the reported zircon to scheelite transition are investigated in detail and compared with those observed in other vanadates. Co-existence of the zircon and scheelite phases is observed over a pressure range of about 8-13 GPa. The zircon to scheelite transition is irreversible upon pressure release. Subtle changes are observed in the Raman spectrum above 16 GPa which could be related to scheelite ↔ fergusonite transition. Pressure dependencies of the Raman active modes in the zircon and the scheelite phases are reported. - Graphical abstract: Study of scheelite-fergusonite transition in RVO 4 by Raman spectroscopy is rare. Here we report Raman spectroscopic investigations of LuVO 4 at high pressure to obtain insight into nature of post-scheelite phases.

International strategic minerals inventory summary report; rare-earth oxides

Science.gov (United States)

Jackson, W.D.; Christiansen, Grey

1993-01-01

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

Spectrographic determination of lanthanides in high-purity uranium compounds, after chromatographic separation by alumina-hydrofluoric acid

International Nuclear Information System (INIS)

Lordello, A.R.; Abrao, A.

1979-01-01

A method is presented for the determination of fourteen rare earth elements in high-purity uranium compounds by emission spectrography. The rare earths are chromatographically separated from uranium by using alumina-hydrofluoric acid. Lanthanum is used both as collector and internal standard. The technique of excitation involves a total consumption of the sample in a 17 ampere direct current arc. The range of determination is about 0.005 to 0.5 μg/g uranium. The coefficient of variation for Pr, Ho, Dy, Er, Tm, Lu, Gd and Tb amounts to 10%. (Author) [pt

Utilization of hydrochloric acid wastes of titanium-magnesium plants for reprocessing of rare earth mineral raw material

International Nuclear Information System (INIS)

Nikonov, V.N.; Troyanker, L.S.; Mikhlin, E.B.

1979-01-01

The possibility of using hydrochloric acid wastes of gas purifying plants in rare earth production is studied in laboratory conditions. It is shown that during sorption leaching of a rare earth product using the KU-2X8 cationite instead the reactive hydrochloric acid one may use hydrochloric acid wastes; rare earth element and yttrium extraction in both cases is identical

Ultraviolet photoluminescence in Gd-doped silica and phosphosilicate fibers

Directory of Open Access Journals (Sweden)

Y. Wang

2017-04-01

Full Text Available Optical fiber lasers operating in the near infrared and visible spectral regions have relied on the spectroscopic properties of rare earth ions such as Yb3+, Er3+, Tm3+, Nd3+, and Sm3+. Here, we investigate Gd3+ doping in phosphosilicate and pure silica fibers using solution doping and sol-gel techniques, respectively, for potential applications in the ultraviolet. Photoluminescence spectra for optical fiber bundles and fiber preforms were recorded and compared. Emissions at 312 nm (phosphosilicate and 314 nm (pure silica were observed when pumping to the Gd3+ 6DJ, 6IJ, and 6PJ = 5/2, 3/2 energy levels. Oxygen deficient center was observed in solution doping sample with a wide absorption band centered at around 248 nm not affecting pumping to 6IJ states.

Electronic and magnetic properties of SmCrSb3 and GdCrSb3: A first principles study

International Nuclear Information System (INIS)

Sandeep; Ghimire, M.P.; Thapa, R.K.

2011-01-01

The density of states (DOS) and the magnetic moments of SmCrSb 3 and GdCrSb 3 have been studied by first principles full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT). For the exchange-correlation potential, the local-spin density approximations with correlation energy (LSDA+U) method have been used. Total and partial DOS have been computed using the WIEN2k code. DOS result shows the exchange-splittings of Cr-3d and rare-earth (R) 4f states electrons, which are responsible for the ground state ferromagnetic (FM) behavior of the systems. The FM behavior of these systems is strongly influenced by the average number of Cr-3d and Sm (Gd) 4f-electrons. The effective moment of SmCrSb 3 is found to be 7.07 μ B while for GdCrSb 3 it is 8.27 μ B . The Cr atom plays a significant role on the magnetic properties due to the hybridization between Cr-3d and Sb-5p states. - Highlights: → DOS and the magnetic moments of SmCrSb 3 and GdCrSb 3 are studied by full-FP-LAPW method. → Exchange splitting of eg and t2g of Cr-3d states and the rare-earth 4f state electrons are responsible for ground state ferromagnetism. → Rare-earth magnetic moments are greater than Cr moment indicating presence of 4f states.

Photostimulated luminescence and defects creation processes in Ce{sup 3+}-doped epitaxial films of multicomponent Lu{sub 3−x}Gd{sub x}Ga{sub y}Al{sub 5−y}O{sub 12} garnets

Energy Technology Data Exchange (ETDEWEB)

Babin, V. [Institute of Physics AS CR, Cukrovarnicka 10, 16253 Prague (Czech Republic); Chernenko, K. [Peter the Great Saint-Petersburg Polytechnic University, Polytekhnicheskaya 29, 195251 St. Petersburg (Russian Federation); Kučera, M. [Charles University, Faculty of Mathematics and Physics, Ke Karlovu 5, 12116 Prague (Czech Republic); Nikl, M. [Institute of Physics AS CR, Cukrovarnicka 10, 16253 Prague (Czech Republic); Zazubovich, S., E-mail: svea@ut.ee [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia)

2016-11-15

Luminescence characteristics of epitaxial films of Ce{sup 3+}-doped multicomponent garnets of the type of Lu{sub 3−x}Gd{sub x}Ga{sub y}Al{sub 5−y}O{sub 12}, where x varies from 0.14 to 3 and y varies from 0 to 3.54, are investigated in the 4.2–400 K temperature range by the steady-state and time-resolved spectroscopy methods. Their dependence on the film composition is clarified. The presence in the same film of different Ce{sup 3+}-related luminescence centers is revealed, and a possible structure of these centers is discussed. The processes of the electron and hole centers creation under irradiation of the films in the Ce{sup 3+}-related absorption bands are studied by thermally stimulated luminescence method. The location of the excited 5d{sub 1} level of Ce{sup 3+} with respect to the bottom of the conduction band and the origin and thermal stability parameters of electron traps in the epitaxial films and in the single crystals of the same composition are found to be different.

Assessing rare earth elements in quartz rich geological samples

International Nuclear Information System (INIS)

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

2016-01-01

Sodium peroxide (Na_2O_2) 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 "1"5"7Gd 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 Na_2O_2/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. - Highlights: • Na_2O_2 fusion coupled to ICP-MS/MS was used to determine REE in quartz-rich samples. • The method accuracy was checked with a geological reference material and INAA. • Results were within 80–98% recovery of QLO-1 reference material, comparable to INAA. • Detection limits were generally below 10 pg g"−"1, and repeatability was below 15%. • Na_2O_2/ICP-MS/MS proved to be a suitable method for REE in quartz-rich samples.

On fluorozirconates and fluorohafnates of rare earths

International Nuclear Information System (INIS)

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

1980-01-01

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

Alternative method to determine Specific Activity of (177)Lu by HPLC.

Science.gov (United States)

Breeman, Wouter A P; de Zanger, Rory M S; Chan, Ho Sze; de Blois, Erik

2015-01-01

Peptide Receptor Radionuclide Therapy (PRRT) with (177)Lu-DOTA-peptides requires (177)Lu with high specific activity (SA) and values >740 GBq (177)Lu per mg Lu to maximise the atom% of (177)Lu over total Lu. Vendors provide SA values which are based on activity and mass of the target, whereas due to "burn-up" of target, these SA values are not accurate. For a radiochemist the SA of (177)Lu is of interest prior to radiolabeling. An alternative method to determine SA was developed by HPLC, which includes a metal titration of a known amount of DOTA-peptide with a known amount of activity ((177)Lu), and a unknown amount of metal ((177+nat)Lu). Based on an HPLC separation of radiometal-DOTA-peptide and DOTA-peptide, and the concordant ratio of these components the metal content ((177+nat)Lu) can be calculated, and eventually the SA of (177)Lu can be accurately determined. These experimentally determined SA values exceeded the estimated values provided by vendors by 27 ± 16%, (range 6-73 %). The deviation of SA values for samples from the same Lu batch was <2% (n ≥ 10). the SA of (177)Lu is apparently often higher as stated by vendors in comparison to the experimentally determined actual values. For this reason, the SA of (177)Lu-DOTA-TATE and other Lu-DOTA-peptides could be increased accordingly.

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

Science.gov (United States)

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

2010-05-01

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

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

International Nuclear Information System (INIS)

Schleid, Thomas; Hartenbach, Ingo

2016-01-01

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

Low-temperature thermal properties of yttrium and lutetium dodecaborides

International Nuclear Information System (INIS)

Czopnik, A; Shitsevalova, N; Pluzhnikov, V; Krivchikov, A; Paderno, Yu; Onuki, Y

2005-01-01

The heat capacity (C p ) and dilatation (α) of YB 12 and LuB 12 are studied. C p of the zone-melted YB 12 tricrystal is measured in the range 2.5-70 K, of the zone-melted LuB 12 single crystal in the range 0.6-70 K, and of the LuB 12 powder sample in the range 4.3-300 K; α of the zone-melted YB 12 tricrystal and LuB 12 single crystals is measured in the range 5-200 K. At low temperatures a negative thermal expansion (NTE) is revealed for both compounds: for YB 12 at 50-70 K, for LuB 12 at 10-20 K and 60-130 K. Their high-temperature NTE is a consequence of nearly non-interacting freely oscillating metal ions (Einstein oscillators) in cavities of a simple cubic rigid Debye lattice formed by B 12 cage units. The Einstein temperatures are ∼254 and ∼164 K, and the Debye temperatures are ∼1040 K and ∼1190 K for YB 12 and LuB 12 respectively. The LuB 12 low-temperature NTE is connected with an induced low-energy defect mode. The YB 12 superconducting transition has not been detected up to 2.5 K

The dependence of critical current density of GdFeCo layer on composition of thermally assisted STT-RAM

Science.gov (United States)

Dai, B.; Zhu, J.; Liu, K.; Yang, L.; Han, J.

2017-07-01

Amorphous rare earth-transitional metal (RETM) GdFeCo memory layer with RE- and TM-rich compositions was fabricated in stacks of GdFeCo (10 nm)/Cu (3 nm)/[Co(0.2 nm)/Pd(0.4 nm)]6. Their magnetic properties and spin transfer torque (STT) switching of magnetization were investigated. The maximum magneto-resistance (MR) was around 0.24% for the TM-rich Gd21.4 (Fe90Co10)78.6 memory layer and was -0.03% for the RE-rich Gd29.0 (Fe90Co10)71.0 memory layer. The critical current densities Jc to switch the GdFeCo memory layers are in the range of 1.4 × 107 A/cm2-4.5 × 107 A/cm2. The dependence of critical current density Jc and effective anisotropy constant Keff on Gd composition were also investigated. Both Jc and Keff have maximum values in the Gd composition range from 21-29 at.%, suitable for thermally assisted STT-RAM for storage density exceeding Gb/inch2.

Thermoanalytical study of the decomposition of yttrium trifluoroacetate thin films

International Nuclear Information System (INIS)

Eloussifi, H.; Farjas, J.; Roura, P.; Ricart, S.; Puig, T.; Obradors, X.; Dammak, M.

2013-01-01

We present the use of the thermal analysis techniques to study yttrium trifluoroacetate thin films decomposition. In situ analysis was done by means of thermogravimetry, differential thermal analysis, and evolved gas analysis. Solid residues at different stages and the final product have been characterized by X-ray diffraction and scanning electron microscopy. The thermal decomposition of yttrium trifluoroacetate thin films results in the formation of yttria and presents the same succession of intermediates than powder's decomposition, however, yttria and all intermediates but YF 3 appear at significantly lower temperatures. We also observe a dependence on the water partial pressure that was not observed in the decomposition of yttrium trifluoroacetate powders. Finally, a dependence on the substrate chemical composition is discerned. - Highlights: • Thermal decomposition of yttrium trifluoroacetate films. • Very different behavior of films with respect to powders. • Decomposition is enhanced in films. • Application of thermal analysis to chemical solution deposition synthesis of films

Electrothermal vaporization inductively coupled plasma mass spectrometry for the determination of trace amount of lanthanides and yttrium in soil with polytetrafluroethylene emulsion as a chemical modifier

International Nuclear Information System (INIS)

He Man; Hu, Bin; Jiang Zucheng

2005-01-01

A method of electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) for the determination of trace lanthanides and yttrium in soil samples with a polytetrafluorethylene (PTFE) emulsion as chemical modifier to promote the vaporization of the analytes from the graphite furnace was developed in this paper. The analytical characteristics, spectral interference and matrix effect of the analytical method were evaluated and critically compared with those of pneumatic nebulization inductively coupled plasma mass spectrometry (PN-ICP-MS). Under the optimized operation conditions, the relative detection limits of lanthanides (La-Lu) and yttrium for ETV-ICP-MS and PN-ICP-MS were 0.4-20 ng l -1 and 1.0-21 ng l -1 , respectively, the absolute detection limits for ETV-ICP-MS were 4-200 fg, which were improved by 1-2 orders of magnitude compared with PN-ICP-MS. While the analytical precision of ETV-ICP-MS is worse than that of PN-ICP-MS, with the R.S.D.s (%) of 4.1-10% for the former and 2.9-7.8% for the latter. Regarding to the matrix effect, both conventional method and stepwise dilution method were employed to observe the effect of matrix and the very similar results were obtained. It was found that the highest tolerance concentration of the matrix is 1000 mg l -1 and 800 mg l -1 for ETV-ICP-MS and PN-ICP-MS, respectively. To assess the accuracy, the proposed method was applied to the determination of trace lanthanides and yttrium in three different soil standard reference materials and one soil sample, and the determined values are in good agreement with the certified values or reference values

Role of Lu and La in the intergranular films on growth of the prism surface in β-Si_3N_4: A molecular dynamics study

International Nuclear Information System (INIS)

Jiang, Yun; Garofalini, Stephen H.

2016-01-01

The different roles of Lu and La in the intergranular film in silicon nitride on the growth morphology are investigated via molecular dynamics simulations. While advanced microscopy shows each rare earth on the prism surface at room temperature, each additive affects the outward (perpendicular) growth of the surface differently. The simulations show the effect of elevated temperature on the adsorption of La and Lu on this surface that affects growth and provides the atomistic mechanism for the different growth morphology. - Graphical abstract: At elevated temperature, Lu ions move away from the surface as it grows, but remain in near contact (a-start, b-end), whereas La ions remain at the surface and prevent growth (c-start, d-end).

Spectrophotometric determination of yttrium with 2-(2-thiazolylazo)-5-dimethylaminophenol

International Nuclear Information System (INIS)

Tsurumi, Chikao; Furuya, Keiichi.

1975-01-01

Spectrophotometric determination of small amounts of yttrium with 2-(2-thiazolylazo)-5-dimethylaminophenol (TAM) in the presence of zephiramine was investigated. The recommended procedures were as follows; 2.0 ml of water, 7.0 ml of TAM-methanolic solution (2x10 -4 mol/l) and 2.0 ml of zephiramine-aqueous solution (1x10 -2 mol/l) were added to a solution containing less than 35 μg of yttrium and its pH was adjusted to 8.0 with 0.1 mol/l ammonium chloride-0.1 mol/l ammonium hydroxide solution. The solution was transferred to a 25 ml volumetric flask and diluted to the mark with water. After 20 minutes, the absorbance at 575 nm against a reagent blank was measured. The color of yttrium-TAM complex is reddish-violet in the presence of zephiramine and is stable for 90 minutes after color development. The yttrium-TAM complex shows an absorption maximum at 575 nm. The absorbance at 575 nm is constant in a pH range from 7.5 to 8.3. The molar extinction coefficient at this wavelength is 7.2x10 4 l.mol -1 .cm -1 . The band obeys Beer's law up to the concentration of 1.4 μg/ml of yttrium. The molar ratio of yttrium to TAM in the complex is 1 : 2. A number of ions interfere with the determination can be masked by the addition of various masking agents and removed in terms of trioctylamine-xylene extraction. Manganese, tantalum, tin(II), citrate and tartrate ions interfere with the determination. (auth.)

Hybrid synchronization of hyperchaotic Lu system

Indian Academy of Sciences (India)

In this paper, we study the hybrid synchronization between two identical hyperchaotic Lu systems. Hybrid synchronization of hyperchaotic Lu system is achieved through synchronization of two pairs of states and anti-synchronization of the other two pairs of states. Active controls are designed to achieve hybrid ...

Luminescence and photo-thermally stimulated defects creation processes in PbWO{sub 4} crystals doped with trivalent rare-earth ions

Energy Technology Data Exchange (ETDEWEB)

Fabeni, P. [Institute of Applied Physics “N.Carrara” (IFAC) of CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino (Firenze) (Italy); Krasnikov, A.; Kärner, T. [Institute of Physics, University of Tartu, Riia 142, 51014 Tartu (Estonia); Laguta, V.V.; Nikl, M. [Institute of Physics AS CR, Cukrovarnicka 10, 16253 Prague (Czech Republic); Pazzi, G.P. [Institute of Applied Physics “N.Carrara” (IFAC) of CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino (Firenze) (Italy); Zazubovich, S., E-mail: svet@fi.tartu.ee [Institute of Physics, University of Tartu, Riia 142, 51014 Tartu (Estonia)

2013-04-15

In PbWO{sub 4} crystals, doped with various trivalent rare-earth A{sup 3+} ions (A{sup 3+}: La{sup 3+}, Lu{sup 3+}, Y{sup 3+}, Ce{sup 3+}, Gd{sup 3+}), electron (WO{sub 4}){sup 3−} and {(WO_4)"3"−–A"3"+} centers can be created under UV irradiation not only in the host absorption region but also in the energy range around 3.85 eV (Böhm et al., 1999; Krasnikov et al., 2010). Under excitation in the same energy range, the UV emission peak at 3.05–3.20 eV is observed. In the present work, the origin of this emission is investigated in detail by low-temperature time-resolved luminescence methods. Photo-thermally stimulated creation of (WO{sub 4}){sup 3−} and {(WO_4)"3"−–A"3"+} centers is studied also in PbWO{sub 4}:Mo,A{sup 3+} crystals. Various processes, which could explain both the appearance of the UV emission and the creation of the {(WO_4)"3"−–A"3"+}-type centers under irradiation of PbWO{sub 4}: A{sup 3+} crystals in the 3.85±0.35 eV energy range, are discussed. The radiative and non-radiative decay of the excitons localized near A{sup 3+} ions is considered as the most probable mechanism to explain the observed features. -- Highlights: ► UV emission of PbWO{sub 4}: A{sup 3+} (A{sup 3+}: La{sup 3+}, Lu{sup 3+}, Y{sup 3+}, Ce{sup 3+}, and Gd{sup 3+}) crystals is studied. ► The emission is ascribed to the radiative decay of excitons localized near A{sup 3+} ions. ► The excitons are created at 3.85 eV excitation by a two-step process. ► Non-radiative decay of the excitons leads to the creation of (WO{sub 4}){sup 3−}–A{sup 3+} centers.

İki uçlu bozukluk 1 ve iki uçlu bozukluk 2 depresyon tedavisi arasındaki farklar

OpenAIRE

Sayar, Kemal

2013-01-01

İki uçlu bozukluk 1 ve 2 depresyonları, klinik açıdan farklılıklar gösterebilmektedir. İki uçlu bozukluk 2 ve iki uçlu bozukluk 1 depresyonların tedavisi arasındaki farklar ise tartışmalı bir alandır. Henüz İki uçlu bozukluk 2 depresyon tedavisi konusunda yeterince kanıt birikmemişse de ilk veriler her iki durumun tedavisinde farklar olması gerektiğini düşündürmektedir. Özellikle antidepresan kullanımı konusunda dikkatli olmak gerekmektedir.

Comparative study using Monte Carlo methods of the radiation detection efficiency of LSO, LuAP, GSO and YAP scintillators for use in positron emission imaging (PET)

International Nuclear Information System (INIS)

Nikolopoulos, Dimitrios; Kandarakis, Ioannis; Tsantilas, Xenophon; Valais, Ioannis; Cavouras, Dionisios; Louizi, Anna

2006-01-01

The radiation detection efficiency of four scintillators employed, or designed to be employed, in positron emission imaging (PET) was evaluated as a function of the crystal thickness by applying Monte Carlo Methods. The scintillators studied were the LuSiO 5 (LSO), LuAlO 3 (LuAP), Gd 2 SiO 5 (GSO) and the YAlO 3 (YAP). Crystal thicknesses ranged from 0 to 50 mm. The study was performed via a previously generated photon transport Monte Carlo code. All photon track and energy histories were recorded and the energy transferred or absorbed in the scintillator medium was calculated together with the energy redistributed and retransported as secondary characteristic fluorescence radiation. Various parameters were calculated e.g. the fraction of the incident photon energy absorbed, transmitted or redistributed as fluorescence radiation, the scatter to primary ratio, the photon and energy distribution within each scintillator block etc. As being most significant, the fraction of the incident photon energy absorbed was found to increase with increasing crystal thickness tending to form a plateau above the 30 mm thickness. For LSO, LuAP, GSO and YAP scintillators, respectively, this fraction had the value of 44.8, 36.9 and 45.7% at the 10 mm thickness and 96.4, 93.2 and 96.9% at the 50 mm thickness. Within the plateau area approximately (57-59)% (59-63)% (52-63)% and (58-61)% of this fraction was due to scattered and reabsorbed radiation for the LSO, GSO, YAP and LuAP scintillators, respectively. In all cases, a negligible fraction (<0.1%) of the absorbed energy was found to escape the crystal as fluorescence radiation

Ni3d-Gd4f correlation effects on the magnetic behaviour of GdNi

Energy Technology Data Exchange (ETDEWEB)

Paulose, P L [Tata Inst. of Fundamental Research, Bombay (India); Patil, Sujata [Tata Inst. of Fundamental Research, Bombay (India); Mallik, R [Tata Inst. of Fundamental Research, Bombay (India); Sampathkumaran, E V [Tata Inst. of Fundamental Research, Bombay (India); Nagarajan, V [Tata Inst. of Fundamental Research, Bombay (India)

1996-07-01

The results of magnetization and heat-capacity measurements on the alloys, Gd{sub 1-x}Y{sub x}Ni (x=0.0, 0.25, 0.5, 0.75 and 0.9) are reported. The data suggest that there is a Gd induced magnetic moment on Ni, which may in turn enhance Gd-Gd exchange interaction strength in GdNi. The induced moment (on Ni) apparently exhibits itinerant ferromagnetism in the magnetically ordered state of GdNi. (orig.).

Evidence of yttrium silicate inclusions in YSZ-porcelain veneers.

Science.gov (United States)

Stoner, Brian R; Griggs, Jason A; Neidigh, John; Piascik, Jeffrey R

2014-04-01

This report introduces the discovery of crystalline defects that can form in the porcelain veneering layer when in contact with yttria-stabilized zirconia (YSZ). The focus was on dental prostheses and understanding the defects that form in the YSZ/porcelain system; however the data reported herein may have broader implications toward the use and stability of YSZ-based ceramics in general. Specimens were cut from fully sintered YSZ plates and veneering porcelain was applied (X-ray (EDAX) was used for microstructural and elemental analysis. EDAX, for chemical analysis and transmission electron diffraction (TED) for structural analysis were both performed in the transmission electron microscope (TEM). Additionally, in order to spatially resolve Y-rich precipitates, micro-CT scans were conducted at varying depths within the porcelain veneer. Local EDAX (SEM) was performed in the regions of visible inclusions and showed significant increases in yttrium concentration. TEM specimens also showed apparent inclusions in the porcelain and selected area electron diffraction was performed on these regions and found the inclusions to be crystalline and identified as either yttrium-silicate (Y2 SiO5 ) or yttrium-disilicate (Y2 Si2 O7 ). Micro-CT data showed that yttrium-silicate precipitates were distributed throughout the thickness of the porcelain veneer. Future studies are needed to determine whether many of the premature failures associated with this materials system may be the result of crystalline flaws that form as a result of high temperature yttrium diffusion near the surfaces of YSZ. © 2013 Wiley Periodicals, Inc.

The Bad Berka dose protocol: comparative results of dosimetry in peptide receptor radionuclide therapy using (177)Lu-DOTATATE, (177)Lu-DOTANOC, and (177)Lu-DOTATOC.

Science.gov (United States)

Schuchardt, Christiane; Kulkarni, Harshad R; Prasad, Vikas; Zachert, Carolin; Müller, Dirk; Baum, Richard P

2013-01-01

The objective of this study is to analyze the in vivo behavior of the (177)Lu-labeled peptides DOTATATE, DOTANOC, and DOTATOC used for peptide receptor radionuclide therapy (PRRNT) of neuroendocrine tumors (NETs), by measuring organ and tumor kinetics and by performing dosimetric calculations. Two hundred fifty-three patients (group 1) with metastasized NET who underwent PRRNT were examined. Out of these, 185 patients received (177)Lu-DOTATATE, 9 were treated with (177)Lu-DOTANOC, and 59 with (177)Lu-DOTATOC. Additionally, 25 patients receiving, in consecutive PRRNT cycles, DOTATATE followed by DOTATOC (group 2) and 3 patients receiving DOTATATE and DOTANOC (group 3) were analyzed. Dosimetric calculations (according to MIRD scheme) were performed using OLINDA software. In group 1, DOTATOC exhibited the lowest and DOTANOC the highest uptake and therefore mean absorbed dose in normal organs (whole body, kidney, and spleen). In group 2, there was a significant difference between DOTATATE and DOTATOC concerning kinetics and normal organ doses. (177)Lu-DOTATOC had the lowest uptake/dose delivered to normal organs and highest tumor-to-kidney ratio. There were no significant differences between the three peptides concerning tumor kinetics and mean absorbed tumor dose. The study demonstrates a correlation between high affinity of DOTANOC in vitro and high uptake in normal organs/whole body in vivo, resulting in a higher whole-body dose. DOTATOC exhibited the lowest uptake and dose delivered to normal tissues and the best tumor-to-kidney ratio. Due to large interpatient variability, individual dosimetry should be performed for each therapy cycle.

Synthesis and physicochemical investigation of complexes of rare earth, alkaline earth elements and copper with some β-diketones

International Nuclear Information System (INIS)

Nichiporuk, R.V.; Pechurova, N.I.; Snezhko, N.I.; Martynenko, L.I.; Kaul', A.R.; Zanina, A.S.; Shergina, S.I.; Sokolov, I.E.

1991-01-01

Complexes of rare earth, alkaline earth elements and copper with 2-methoxy-2,6,6-trimethylheptanedion-3,5 as well as complexes of yttrium and barium with 2-methoxy-2,6-dimethylheptanedion-3,5 were synthesized. Prepared complexes were investigated by the methods of chemical, thermal, X-ray phase analyses, IR spectroscopy. Complex sublimation was studied at 10 -1 -10 -2 mm Hg. Complexes of rare earths and copper don't change their composition during sublimation, and sublimation of hydrated complexes of barium, strontium and calcium leads to formation of anhydrous complexes. All prepared complexes are able to transsublimate multiply and qualitatively without change of composition. All isolated complexes can be used for preparation of film oxide coatings by CVD method

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

Science.gov (United States)

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.

Evaluation of Gd and Gd{sup 159} as new approaches for cancer treatment

Energy Technology Data Exchange (ETDEWEB)

Galvao, I.; Neves, M.J., E-mail: nevesmj@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Grupo de Desenvolvimento de Radiofarmacos; Santos, R.G., E-mail: santosr@cdtn.br [Instituto Nacional de Ciencia e Tecnologia em Medicina Molecular (INCT-MM), Belo Horizonte, MG (Brazil)

2011-07-01

Metal compounds have shown many biological activities and have been successfully used as anticancer agents such cisplatin. Actually gadolinium (Gd) complexed with a porphyrin Motexafin (MGd) has been investigated as redox-active compound for treatment of cancer. 1{sup 59G}d decays by beta emission with an energy of 970 keV and half-life of 18.59 hours. The de-excitation can be via gamma ray and internal conversion electron emission followed by auger electrons and x rays. Considering all of this 1{sup 59G}d could be a interesting radionuclide to be as a radio therapeutical agent. The aims of this works were to evaluate the cytotoxicity of Gd and 1{sup 59G}d on malignant brain tumors such as glioblastoma multiform, the most frequent brain tumors which has a very poor prognosis. For this purpose, it was used human glioblastoma cell lines T98 (mutant p53) and U87 (wild-type p53) to investigate the cytotoxicity of gadolinium on cell metabolism by MTT assay and also morphological changes, chromatin condensation by DAPI assay and ROS generation. Gadolinium was able to decrease cell viability, the cells presented morphological changes like round shapes and blebs formation after cell treatment with 5x10{sup -6}M of Gd. Nuclear changing and ROS generation occurred in a dose dependent way indicating the cytotoxic effect of Gd. Treatment with 1{sup 59G}d increased all of changes observed with treatment with Gd. These results state for an additive effect of metal toxicity and radioactivity inducing ROS generation as the main mechanism of anti tumoral action of 1{sup 59G}d. The results obtained indicated that the radioactive analogues of Gd have increased cytotoxic effects and gadolinium can be a metal of choice for development of new drugs for cancer treatment. (author)

Attempts at treating rheumatoid arthritis with radioactive yttrium

International Nuclear Information System (INIS)

Scott, J.T.

1979-01-01

Two years' observations on 33 knee joints in 33 patients with rheumatoid arthritis did not prove a therapeutic effect of Y 90 , which was tested in a randomized study against non-radioactive yttrium. It was noticable that 9 knee joints of the isotope group but only one of the control group became unstable. Independent of the yttrium treatment, significant improvement was noticed in patients where fibrin clots had been washed out of the joints in the course of arthroscopies. (orig.) [de

Mälu defragmenteerimine / Ilja Sundelevitsh

Index Scriptorium Estoniae

Sundelevitsh, Ilja

2007-01-01

Viktor Misiano kureeritud projekt "Mälu tagasitulek" Kumu Kunstimuuseumis kuni 29. VII. Dmitri Gutovi projektist, mis koosneb videotest "Sula" ja "Kajakad" ning kolmest maalist, Valentin Arhipovi projektist "Vassili Grigorjevitsh Arhipovi looming aastail 1962-2006", Juri Leidermani heliinstallatsioonist "Isa jutustus", Jevgeni Fiksi projektist, Gljuklja & Tzaplja (Olga Jegorova, Natalja Pershina) installatsioonist "Punased purjed", Igor Shtsherbini tööst "Defragmenteerimine. Stirlitzi mälu" ja Sergei Bratkovi tööst

Investigations on fabricating strategies and utilization of rare earth based multicomponent oxide powders in radiation detection

International Nuclear Information System (INIS)

Shinde, Seema; Pitale, S.S.; Banthia, S.; Ghosh, M.; Tyagi, M.; Sen, S.; Gadkari, S.C.

2014-01-01

Materials containing rare earths demonstrate a broad field of applications as high energy radiation detectors, mainly due to their fascinating optical properties. Currently, Ce 3+ -doped rare earth silicates and garnets dominate the scintillator market because they show a high light yield, fast decay time, and high chemical stability. Moreover, the emission wavelength of silicates (410-440 nm) matches the wavelength sensitivity of conventional PMTs while, Si-photo-detector readouts are possible with garnets (emission near 550 nm). The composition, structure and phase of rare earth silicates are rather complex. For example, there are many phases like oxyorthosilicate R 2 SiO 5 , disilicate R 2 Si 2 O 7 , hexagonal R x (SiO 4 ) 6 O 2 oxyapatite etc (where R= Rare earth element). The controlled synthesis of single phase rare earth silicates and garnets nanomaterials is not easy and can only be reached with precisely controlled experimental conditions. In this work, we provide a broad overview of our recent scientific developments linked to a few aspects of synthesizing cerium activated rare earth based silicates and garnet materials, namely Gd 2 SiO 5 :Ce 3+ , Gd 4.67 (SiO 4 ) 3 O, Gd 2 Si 2 O 7 :Ce 3+ and Gd 3 Al x Ga 1-x O 12 :Ce 3+ (where 0≤x≤5) exploiting the advantages of solution combustion, chemical co-precipitation and hydrothermal techniques. A brief summary of results based on synthesis strategy adopted, composition, size shape and corresponding luminescence features of Gd based compounds are tabulated. The room temperature photoluminescence (PL) features of compounds listed. Efforts towards finding new properties and new materials will be continued and several applications, in particular energy-conversion and scintillator detectors, will benefit from these rare earth materials

Process for recovering yttrium and lanthanides from wet-process phosphoric acid

Energy Technology Data Exchange (ETDEWEB)

Janssen, J.A.; Weterings, C.A.

1983-06-28

Process for recovering yttrium and lanthanides from wet-process phosphoric acid by adding a flocculant to the phosphoric acid, separating out the resultant precipitate and then recovering yttrium and lanthanides from the precipitate. Uranium is recovered from the remaining phosphoric acid.

Yttrium-90 - ED 4310

International Nuclear Information System (INIS)

Ammerich, M.; Frot, P.; Gambini, D.; Gauron, C.; Moureaux, P.; Herbelet, G.; Lahaye, T.; Pihet, P.; Rannou, A.; Vidal, E.

2013-03-01

This sheet presents the characteristics of yttrium-90, its origin, and its radio-physical and biological properties. It briefly describes its use in nuclear medicine. It indicates its dosimetric parameters for external exposure, cutaneous contamination, and internal exposure due to acute contamination or to chronic contamination. It indicates and comments the various exposure control techniques: ambient dose rate measurement, surface contamination measurement, atmosphere contamination. It addresses the means of protection: premise design, protection against external exposure and against internal exposure. It describes how areas are delimited and controlled within the premises: regulatory areas, controls to be performed. It addresses the personnel classification, training and medical survey. It addresses the issue of solid and liquid wastes and liquid or gaseous effluents. It briefly recalls the administrative procedures related to the authorization and declaration of possession and use of sealed and unsealed sources. It indicates regulatory aspects related to the transport of yttrium-90, describes what is to be done in case of incident or accident (for the different types of contamination or exposure)

Preparation, thermogravimetric study and infrared spectra of rare earth acetates

International Nuclear Information System (INIS)

Graehlert, X.; Starke, M.

1992-01-01

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

First evidence for triaxial superdeformation in sup 1 sup 6 sup 1 Lu and sup 1 sup 6 sup 2 Lu

CERN Document Server

Bringel, P; Domscheit, J; Neusser, A; Schoenwasser, G; Singh, A K; Amro, H; Axiotis, M; Kröll, T; Napoli, D R; Bazzacco, D; Lunardi, S; Ur, C; Bhattacharya, S; Bhowmik, R; Hagemann, G B; Jensen, D R; Pancholi, S C; Petrache, C M

2003-01-01

High-spin states in sup 1 sup 6 sup 1 Lu and sup 1 sup 6 sup 2 Lu have been investigated using the GASP gamma-ray spectrometer array. Excited states in these nuclei have been populated through the sup 1 sup 0 sup 0 Mo( sup 6 sup 5 Cu, xn) reaction at a beam energy of 260 MeV. Four presumably triaxial superdeformed bands, three in sup 1 sup 6 sup 2 Lu and one in sup 1 sup 6 sup 1 Lu, have been observed. This is the first evidence for triaxial superdeformation in the two isotopes. (orig.)

Photocatalysis of Yttrium Doped BaTiO3 Nanofibres Synthesized by Electrospinning

Directory of Open Access Journals (Sweden)

Zhenjiang Shen

2015-01-01

Full Text Available Yttrium doped barium titanate (BT nanofibres (NFs with significant photocatalytic effect were successfully synthesized by electrospinning. Considering the necessary factors for semiconductor photocatalysts, a well-designed procedure was carried out to produce yttrium doped BT (BYT NFs. In contrast to BYT ceramics powders and BT NFs, BYT NFs with pure perovskite phase showed much enhanced performance of photocatalysis. The surface modification in electrospinning and subsequent annealing, the surface spreading of transition metal yttrium, and the narrowed band gap energy in yttrium doping were all contributed to the final novel photocatalytic effect. This work provides a direct and efficient route to obtain doped NFs, which has a wide range of potential applications in areas based on complex compounds with specific surface and special doping effect.

The magnetic structure of GdNi2B2C investigated by neutron powder diffraction

International Nuclear Information System (INIS)

Barcza, A.; Rotter, M.; Doerr, M.; Beuneu, B.

2005-01-01

Full text: The group of ReT 2 B 2 C (Re=rare earth, T=transition metal) shows a very interesting interplay between magnetism and superconductivity due to the rare earth metals. In this work the magnetism of GdNi 2 B 2 C was studied with neutron diffraction. Previous investigations with x-ray diffraction methods have determined the crystal structure as a body centered tetragonal structure (I 4/mmm). Hot neutrons were used for the diffraction experiment, because the absorption cross section of Gd is significantly smaller for short wavelengths. The investigated compound orders magnetically at TN=19.5 K, and so the experiment was carried out at two temperatures, namely 30 K and 2.2 K. The results show a incommensurate spin structure with a propagation vector of (0.55 0 0). To confirm this results additional simulations of the spin structure were done based on the Standard Model of rare earth magnetism. A neutron diffraction pattern was calculated using the McPhase program package and is compared to the experimental data. (author)

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

Science.gov (United States)

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...

Magnetic rare earth superlattices

DEFF Research Database (Denmark)

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

1991-01-01

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

Thermoluminescence of double fluorides doped with rare earths; Termoluminiscencia de fluoruros dobles dopados con tierras raras

Energy Technology Data Exchange (ETDEWEB)

Azorin N, J.; Sanchez R, A. [UAM-I, 09340 Mexico D.F. (Mexico); Khaidukov, N.M. [Kurnakov Institute of General and Inorganic Chemistry, 119991 Moscow (Russian Federation)

2004-07-01

In this work the thermoluminescent characteristics of double fluorides K{sub 2}YF{sub 5}, K{sub 2}GdF{sub 5} and K{sub 2}LuF{sub 5} doped are presented with Tb{sup 3+}, studied in the interval of temperature from 30 to 400 C. The materials that presented better answer to the irradiation with particles beta and with ultraviolet light they were the K{sub 2}YF{sub 5}: Tb (1% at. Tb{sup 3+}) and the K{sub 2}LuF{sub 5}: Tb (1% at. Tb{sup 3+}); while the K{sub 2}YF{sub 5}: Tb to high concentrations (10% and 20% at. Tb{sup 3+}) and the K{sub 2}LuF{sub 5}: Tb (1% at. Tb{sup 3+}) and the K{sub 2}LuF{sub 5}: Tb (1% at. Tb{sup 3+}) they presented an acceptable answer in front of the gamma radiation. The intensity of the Tl answer induced in these materials is a decisive factor to continue studying its dosimetric characteristics, what allows to consider them as the base for the development of potential materials to use them in the dosimetry of beta particles, of the UV light of the gamma radiation using the thermoluminescence method. (Author)

Determination of rare earth element content in yttrium aluminium garnet crystals by absorption spectrophotometry method

International Nuclear Information System (INIS)

Mejl'man, M.L.; Kolomijtsev, A.I.; Baskakova, Z.M.; Bagdasarov, Kh.S.; Kevorkov, A.M.

1985-01-01

Possibility of determination of relative and absolute contents of impurity trivalent REE ions in yttrium aluminium garnet of (YAG) monocrystals has been studied by the absorption spectrophotometry method. Absorption spectra in UV and visible regions YAG monocrystals doped by REE are studied. For each admixture the characteristic lines or absorption bands not overlapping with lines of other admixtures are defined and investigated. The extinction coefficients of characteristic lines are determined which allow one to measure absolute REE admixture concentrations in garnet crystals. A conclusion is drawn that the absorption spectrophotometry method permits to measure REE admixture content in YAG monocrystals within the concentration range of approximately 1x10sup(-3)-5 mas. % with an accuracy not less than 20% (with sample thickness of approximately 1 cm)

The behaviour of selected yttrium containing bioactive glass microspheres in simulated body environments.

Science.gov (United States)

Cacaina, D; Ylänen, H; Simon, S; Hupa, M

2008-03-01

The study aims at the manufacture and investigation of biodegradable glass microspheres incorporated with yttrium potentially useful for radionuclide therapy of cancer. The glass microspheres in the SiO2-Na2O-P2O5-CaO-K2O-MgO system containing yttrium were prepared by conventional melting and flame spheroidization. The behaviour of the yttrium silicate glass microspheres was investigated under in vitro conditions using simulated body fluid (SBF) and Tris buffer solution (TBS), for different periods of time, according to half-life time of the Y-90. The local structure of the glasses and the effect of yttrium on the biodegradability process were evaluated by Fourier Transform Infrared (FT-IR) spectroscopy and Back Scattered Electron Imaging of Scanning Electron Microscopy (BEI-SEM) equipped with Energy Dispersive X-ray (EDX) analysis. UV-VIS spectrometry and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used for analyzing the release behaviour of silica and yttrium in the two used solutions. The results indicate that the addition of yttrium to a bioactive glass increases its structural stability which therefore, induced a different behaviour of the glasses in simulated body environments.

High spin K isomeric target of {sup 177m}Lu

Energy Technology Data Exchange (ETDEWEB)

Roig, O. E-mail: olivier.roig@cea.fr; Belier, G.; Daugas, J.-M.; Delbourgo, P.; Maunoury, L.; Meot, V.; Morichon, E.; Sauvestre, J.-E.; Aupiais, J.; Boulin, Y.; Fioni, G.; Letourneau, A.; Marie, F.; Ridikas, D

2004-03-21

The techniques used to produce a {sup 177m}Lu (J{sup {pi}}=23/2{sup -},T{sub 1/2}=160.4 days) target are described in this paper. Firstly, an isotopic separation of an enriched lutetium sample was used to reach a purity of {sup 176}Lu close to 99.993%. Afterwards, the high neutron flux of the Grenoble Institut Laue-Langevin reactor was used to produce the {sup 177m}Lu isomer by the {sup 176}Lu(n,{gamma}) reaction. Finally, a chemical separation was performed to extract 10{sup 13} nuclei of {sup 177m}Lu. Thanks to this experiment, we have been able to estimate the destruction cross-section of the {sup 177m}Lu.

Neutron capture reactions on Lu isotopes at DANCE

CERN Document Server

Roig, O

2010-01-01

The DANCE (Detector for Advanced Neutron Capture Experiments) array located at the Los Alamos national laboratory has been used to obtain the neutron capture cross sections for 175Lu and 176Lu with neutron energies from thermal up to 100 keV. Both isotopes are of current interest for the nucleosynthesis s-process in astrophysics and for applications as in reactor physics or in nuclear medicine. Three targets were used to perform these measurements. One was natLu foil and the other two were isotope-enriched targets of 175Lu and 176Lu. The cross sections are obtained for now through a precise neutron flux determination and a normalization at the thermal neutron cross section value. A comparison with the recent experimental data and the evaluated data of ENDF/B-VII.0 will be presented. In addition, resonances parameters and spin assignments for some resonances will be featured.

Yttrium aluminum garnet coating on glass substrate

Energy Technology Data Exchange (ETDEWEB)

Ferreira, Camila M.A.; Freiria, Gabriela S.; Faria, Emerson H. de; Rocha, Lucas A.; Ciuffi, Katia J.; Nassar, Eduardo J., E-mail: eduardo.nassar@unifran.edu.br

2016-02-15

Thin luminescent films have seen great technological advances and are applicable in the production of a variety of materials such as sensors, solar cells, photovoltaic devices, optical magnetic readers, waveguides, lasers, and recorders. Systems that contain yttrium aluminum oxide are important hosts for lanthanide ions and serve as light emission devices. This work deals with the deposition of yttrium aluminum garnet (YAG) film doped with Eu{sup 3+} onto a glass substrate obtained by the sol–gel methodology. Spray pyrolysis furnished the yttrium aluminum oxide powder. Dip-coating at a withdrawal speed of 10 mm min{sup −1} and evaporation led to deposition of different numbers of layers of the YAG:Eu{sup 3+} film onto the glass substrate from a YAG:Eu{sup 3+} powder suspension containing ethanol, water, and tetraethylorthosilicate. Photoluminescence, X-ray diffraction, scanning electron microscopy, and transparency measurements aided film characterization. The emission spectra revealed that the number of layers influenced film properties. - Highlights: • The spray pyrolysis was used to obtain luminescent YAG:Eu{sup 3+}. • The matrix was deposited as transparent films. • The YAG:Eu{sup 3+} was deposited by sol–gel process onto glass substrate.

Yttrium addition for high temperatures stainless steel

International Nuclear Information System (INIS)

Furtado, Nelson Cesar Chaves Pinto

1997-07-01

The current work studied the effect of Yttrium on the microstructure of 2% Nb, modified - HP steel, with respect to its mechanical properties. Alloys were prepared with nominal Yttrium additions of 0,1% and 0,25%. Microstructural analyses and mechanical tests were undertaken in the as-cast condition and after ageing for 100 h at 700 deg C, 900 deg C and 1100 deg C. Structural characterization was performed by optical microscopy, scanning and transmission electron microscopy (SEM/TEM/EDS), X-ray diffractometry and X-ray photoelectron spectroscopy (XPS). Tensile testing was performed at room temperature and 871 deg C and creep testing at 925 deg C at a loading of 55 MPa. The material produced exhibited superior mechanical properties and surface oxidation resistance than traditional alloys of this class, even through gravity cast in a magnetic furnace. Agglomerates of Yttrium-rich phases were identifies in both as-cast and aged specimens, always associated with chromium carbides of characteristic morphologies. These morphologies, combined with the microstructural constituents, may have established the factors which resulted in the improved metallurgical stability of these alloys under the experimental testing conditions and temperatures which simulated real industrial service conditions and temperatures. (author)

Yttrium aluminum garnet coating on glass substrate

International Nuclear Information System (INIS)

Ferreira, Camila M.A.; Freiria, Gabriela S.; Faria, Emerson H. de; Rocha, Lucas A.; Ciuffi, Katia J.; Nassar, Eduardo J.

2016-01-01

Thin luminescent films have seen great technological advances and are applicable in the production of a variety of materials such as sensors, solar cells, photovoltaic devices, optical magnetic readers, waveguides, lasers, and recorders. Systems that contain yttrium aluminum oxide are important hosts for lanthanide ions and serve as light emission devices. This work deals with the deposition of yttrium aluminum garnet (YAG) film doped with Eu 3+ onto a glass substrate obtained by the sol–gel methodology. Spray pyrolysis furnished the yttrium aluminum oxide powder. Dip-coating at a withdrawal speed of 10 mm min −1 and evaporation led to deposition of different numbers of layers of the YAG:Eu 3+ film onto the glass substrate from a YAG:Eu 3+ powder suspension containing ethanol, water, and tetraethylorthosilicate. Photoluminescence, X-ray diffraction, scanning electron microscopy, and transparency measurements aided film characterization. The emission spectra revealed that the number of layers influenced film properties. - Highlights: • The spray pyrolysis was used to obtain luminescent YAG:Eu 3+ . • The matrix was deposited as transparent films. • The YAG:Eu 3+ was deposited by sol–gel process onto glass substrate.

Yttrium-90 microspheres for the treatment of hepatocellular carcinoma.

Science.gov (United States)

Geschwind, Jean Francois H; Salem, Riad; Carr, Brian I; Soulen, Michael C; Thurston, Kenneth G; Goin, Kathleen A; Van Buskirk, Mark; Roberts, Carol A; Goin, James E

2004-11-01

Unresectable hepatocellular carcinoma is extremely difficult to treat. TheraSphere consists of yttrium-90 (a pure beta emitter) microspheres, which are injected into the hepatic arteries. This article reviews the safety and survival of patients with hepatocellular carcinoma who were treated with yttrium-90 microspheres. Eighty patients were selected from a database of 108 yttrium-90 microsphere-treated patients and were staged by using Child-Pugh, Okuda, and Cancer of the Liver Italian Program scoring systems. Patients were treated with local, regional, and whole-liver approaches. Survival from first treatment was analyzed with Kaplan-Meier and Cox regression methods. Adverse events and complications of treatment were coded by using the Southwest Oncology Group toxicity scoring system. Patients received liver doses ranging from 47 to 270 Gy. Thirty-two patients (40%) received more than 1 treatment. Survival correlated with pretreatment Cancer of the Liver Italian Program scores ( P = .002), as well as with the individual Cancer of the Liver Italian Program components, Child-Pugh class, alpha-fetoprotein levels, and percentage of tumor replacement. Patients classified as Okuda stage I (n = 54) and II (n = 26) had median survival durations and 1-year survival rates of 628 days and 63%, and 384 days and 51%, respectively ( P = .02). One patient died of liver failure judged as possibly related to treatment. Thus, in selected patients with hepatocellular carcinoma, yttrium-90 microsphere treatment is safe and well tolerated. On the basis of these results, a randomized controlled trial is warranted comparing yttrium-90 microsphere treatment with transarterial chemoembolization by using the Cancer of the Liver Italian Program system for prospective stratified randomization.

Iron corrosion inhibition by phosphonate complexes of rare earth metals

International Nuclear Information System (INIS)

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

1993-01-01

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

Transition to intermediate valence state and x-ray photoemission in Sm/sub 1-x/Gd/sub x/S

International Nuclear Information System (INIS)

Campagna, M.; Chui, S.T.; Wertheim, G.K.; Tosatti, E.

1976-01-01

We report a systematic x-ray photoemission study of the alloys Sm 1 /sub -//subx/Gd/subx/S for 0 2+ → Sm 3+ photoemission line shape using a model which has some similarities with the Jaccarino-Walker model for magnetic alloys. It assumes the existence of only two different kinds of Sm 2+ ions in Sm 1 /sub -//subx/Gd/subx/S for x approximately-less-than 16%. We discuss possible reasons for the fact that Gd does not show the usual clustering effects known to occur in many substitutional rare-earth alloys. Lattice-constant measurements for various substituents further illustrate the importance of electronic effects in the phase transition

Calculation of the band structure of GdCo2, GdRh2 e GdIr2 by the APW method

International Nuclear Information System (INIS)

Carvalho, J.A.B. de.

1974-03-01

The band structure of GdCo 2 , GdRh 2 , GdIr 2 has been calculated by the APW method. A histogram of the density of states is presented for each compound. The bands are transition-metal-like, with s-d hybridization near the Fermi level. The 5d character near the Fermi level increases as one goes from Co to Ir

Some particularities of impurity center structure in concentrated solid solutions MeF2-GdF3, where Me-Ca2+, Sr2+ and Ba2+

International Nuclear Information System (INIS)

Karelin, V.V.; Orlov, Yu.N.; Bozhevol'nov, V.E.; Ivanov, L.N.

1981-01-01

The monocrystalline CaF 2 -GdF 3 , SrF 2 -GdF 3 and BaF 2 -GdF 3 systems are studied using the methods of EPR, photo-, radio-, cathode- and thermoluminescence. It is shown that the structure of fluorite solid solutions changes considerably with the growth of the rare earth component concentration. At that, in the systems investigated at least three concentration regions can be singled out: (up to 1%; from 1 to 15%, and > 15% GdF 3 ) which are characterized by their certain selection of impurity centres [ru

Identification of rare earth elements by their fluorescence complexes with tetracycline

International Nuclear Information System (INIS)

Zanotti-Cavazzoni, J.C.; Boveda V, J.C.; Abrao, A.

1994-01-01

A procedure for identification of rare earth elements (REE) based on the complex formation with tetracycline (TC) and visual observation under ultraviolet light is described. One micro drop of REE chloride is placed over the filter paper impregnated with tetracycline and previously dried before use. After dried (30-60 O C) the paper is examined under the UV light. In a second procedure for the identification of mixture of REE a drop of the analyte is added over a filter paper strip impregnated with TC followed by a chromatographic development using a 2:1:1:1 (vol/vol) ethanol, acetone, ether and 1% acetic acid mixture of pH 5,8. After dried, the strip is observed under UV light. Sc, Y, La, Dy, Ho and Lu exhibited high yellow fluorescence; Gd, Tm and Yb a weak yellow; Ce an intense violet; Pr, ND, Sm and Tb violet: Eu a high red fluorescence and Er a violet brown wish, not well defined. It is possible to identify for instance 0.3 ug Ce (concentration 6 mg/L) and 0.2 ug Er (concentration 6 mg/L). Preliminary experiments indicated that those REE-TC chelates can be used for the identification and determination of the REE by spectro fluorimetry. (author). 30 refs

Raman scattering of rare earth hexaborides

International Nuclear Information System (INIS)

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

2009-01-01

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

Nuclear spectroscopy in the rare earth region near the proton drip line

International Nuclear Information System (INIS)

Toth, K.S.; Nitschke, J.M.; Wilmarth, P.A.; Vierinen, K.S.

1989-01-01

We have used the isotope separator facility OASIS, on-line at the Lawrence Berkeley Laboratory SuperHILAC, to investigate rare earth nuclei close to the proton drip line. Single-particle states near the 82-neutron shell have been examined and their excitation energies determined. Numerous new isotopes, isomers, and β-delayed proton emitters have been discovered. In addition, the α-decay properties of nuclides with N ≥ 84 have been reexamined; this has led to the discovery of several previously unobserved α transitions. The overall experimental program is summarized and some recently obtained results on 145 Dy, 147 Er, 147 Tm, 153 Lu, 155 Lu, and 157 Lu are discussed. 20 refs., 11 figs., 11 tabs

Regularity in the formation of compounds in ternary R-Me-Sn systems, R - REM, Me - Fe, Co, Ni, Cu

International Nuclear Information System (INIS)

Skolozdra, R.V.; Komarovskaya, L.P.; Koretskaya, O.Eh.

1992-01-01

For the ternary alloy systems of (La, Y, Gd, Lu)-Fe-Sn, (Ce, Y, Gd)-Co-Sn, (Ce, Y, Gd, Lu)-Ni-Sn and (Pr, Gd, Lu)-Cu-Sn isothermal sections of phase diagrams were plotted within the range of 670 to 870 K. It was revealed that substitution of transition metal in the kFe-Co-Ni-Cu series led to changes both in a number of ternary stannides and their structural types. A tendency was observed in change of stannide numbers depending on quantity ratio of R and Me components. Crystallochemical analysis of compounds obtained showed that they could be treated as interstitial structures or lsuperstructures with respect to them. The results of magnetic properties measurements were used for explanation of structural features of ternary compounds considered

Conversion of green emission into white light in Gd{sub 2}O{sub 3} nanophosphors

Energy Technology Data Exchange (ETDEWEB)

Jayasimhadri, M.; Ratnam, B.V. [Department of Physics, Changwon National University, Changwon, 641-773 (Korea, Republic of); Jang, Kiwan, E-mail: kwjang@changwon.ac.k [Department of Physics, Changwon National University, Changwon, 641-773 (Korea, Republic of); Lee, Ho Sueb [Department of Physics, Changwon National University, Changwon, 641-773 (Korea, Republic of); Yi, Soung-Soo [Department of Photonics, Silla University, Busan (Korea, Republic of); Jeong, Jung-Hyun [Department of Physics, Pukyong National University, Busan (Korea, Republic of)

2010-09-01

Gd{sub 2}O{sub 3} nanophosphors were prepared by combustion synthesis with and without doping of Dy{sup 3+} ions. The X-ray powder diffraction patterns indicate that as-prepared Gd{sub 2}O{sub 3} and 0.1 mol% Dy{sub 2}O{sub 3} doped Gd{sub 2}O{sub 3} nanophosphors have monoclinic structures. The transmission electron microscope (TEM) studies revealed that the as-prepared phosphors had an average crystallite sizes around 37 nm. The excitation and emission properties have been investigated for Dy{sup 3+} doped and undoped Gd{sub 2}O{sub 3} nanophosphors. New emission bands were observed in the visible region for Gd{sub 2}O{sub 3} nanophosphors without any rare earth ion doping under different excitations. A tentative mechanism for the origin of luminescence from Gd{sub 2}O{sub 3} host was discussed. Emission properties also measured for 0.1 mol% Dy{sup 3+} doped Gd{sub 2}O{sub 3} nanophosphors and found the characteristic Dy{sup 3+} visible emissions at 489 and 580 nm due to {sup 4}F{sub 9/2} {yields} {sup 6}H{sub 15/2} and {sup 4}F{sub 9/2} {yields} {sup 6}H{sub 13/2} transitions, respectively. The chromaticity coordinates were calculated based on the emission spectra of Dy{sup 3+} doped and undoped Gd{sub 2}O{sub 3} nanophosphors and analyzed with Commission Internationale de l'Eclairage (CIE) chromaticity diagram. These nanophosphors exhibit green color in undoped Gd{sub 2}O{sub 3} and white color after adding 0.1 mol% Dy{sub 2}O{sub 3} to Gd{sub 2}O{sub 3} nanophosphors under UV excitation. These phosphors could be a promising phosphor for applications in flat panel displays.

Synthesis of yttrium silicate luminescent materials by sol-gel method

International Nuclear Information System (INIS)

Arkhipov, D.V.; Vasina, O.Yu.; Popovich, N.V.; Galaktionov, S.S.; Soshchin, N.P.

1996-01-01

Several yttrium-silicate composition with Y 2 O 3 content within 44-56% have been synthesized. it is ascertained that employment of sol-gel technique permits preparation of luminescent materials on yttrium silicate basis, which compare favourably with bath-produced specimens. The influence of phase composition of sol-gel phosphors on basic performance indices: intensity and luminescence spectrum, has been analyzed

Comparison of tumour and whole body absorbed doses of 177-Lu-DOTA-TATE and Lu-177-DOTA-NOC treatment in the same patient group

International Nuclear Information System (INIS)

Yeyin, N.; Kabasakal, L.; Akyel, R.; Demir, M.; Kanmaz, B.; Ocak, M.; Toklu, T.; Selcuk, N.

2015-01-01

Full text of publication follows. Peptide Receptor Radionuclide Therapy (PRRT) with Lu-177 labelled peptides in patients with neuroendocrine tumours (NETs) aroused great interest. An estimation of actual radiation doses to tumours is very important for therapy planning. There are several radiolabelled peptides, which can be used for PRRT with different biological behaviour. Aim: the aim of the study was to compare the tumour and normal organ absorbed doses in patients who have received Lu-177-DOTA-TATE and Lu-177 DOTA-NOC. Materials and methods: study was composed of 20 patients (M/F: 10/10, mean age: 51.5 ± 14.9) with histologically proven inoperable NETs. All patients received Lu-177-DOTA-NOC treatment 6 to 12 weeks after last Lu-177-DOTA-TATE treatment. Dosimetric calculations were performed using MIRD scheme and lesion doses were calculated using post therapy whole body images obtained at 4, 20, 44, and 68 hours after injection. Tumour volumes were determined from CT images. Thirteen blood samples beginning from time zero to 4 days after injection were obtained for bone marrow and whole body dosimetry. Results: There were 53 lesions in Lu-177-DOTA-TATE post-therapy whole body images and 49 lesions in Lu-177 DOTA-NOC post therapy images. Lesions were selected according to lesion delineation and superimposed lesions were excluded. Mean lesion absorbed dose is calculated to be 47.4 ± 53.4 and 42.9 ± 52.8 Gy per 370 MBq for Lu-177-DOTA-TATE and DOTA-NOC respectively (p>0.5). There were significantly higher absorbed doses for kidney and bone marrow after Lu-177-DOTA-NOC treatment as compared to Lu-177-DOTA-TATE treatment, which were 6.9 ± 2.7 vs 3.9 ± 1.7 (p<0.05) and 0.12 ± 0.0 vs 0.10 ± 0.0 (p<0.05) Gy, respectively. There was not any difference in plasma elimination times between two tracers. On the other hand the whole body absorbed dose was significantly higher after Lu-177-DOTA-NOC treatment, which was 0.24 ± 0.07 vs 0.20 ± 0.06 Gy (p<0