Sample records for dy tb gd

  1. Hydrogen interaction with IMC RNi (R = Sm, Tb, Gd, Dy)

    Microsoft Academic Search

    Y. L. Yaropolov; V. N. Verbetsky; V. A. Somenkov; V. P. Glazkov

    2011-01-01

    The hydrogenation of GdNi, TbNi, DyNi and SmNi at room temperature and hydrogen pressure below 1 atm has been studied. Ternary hydrides GdNiH3.2, TbNiH3.4, DyNiH3.4 and SmNiH3.7 crystallize in orthorhombic CrB-type structure (S.G. Cmcm). The hydrides formation is accompanied with the strong lattice expansion. On the basis of neutron diffraction patterns refinement the atomic positions of D atoms and interatomic

  2. Structure and magnetic properties of RNi (R = Gd, Tb, Dy, Sm) and R 6M 1.67Si 3 (R = Ce, Gd, Tb; M = Ni, Co) hydrides

    Microsoft Academic Search

    Yu. L. Yaropolov; A. S. Andreenko; S. A. Nikitin; S. S. Agafonov; V. P. Glazkov; V. N. Verbetsky

    2011-01-01

    The paper reports the influence of hydrogen absorption on the structure and magnetic properties of intermetallic compounds RNi (R=Gd, Tb, Dy, Sm) and R6M1.67Si3 (R=Ce, Gd, Tb; M=Ni, Co). It is demonstrated that the ternary hydrides GdNiH3.2, TbNiH3.4, DyNiH3.4, and SmNiH3.7 have similar CrB-type orthorhombic structures. In the structures of TbNiD3.4 and DyNiD3.4, deuterium atoms occupy tetrahedral 8f-interstices [R3Ni], trigonal

  3. Influence of hydrogenation on magnetic interactions in intermetallic RNi (R = Gd, Tb, Dy) compounds

    Microsoft Academic Search

    W. Iwasieczko; H. Drulis; Yu. L. Yaropolov; S. A. Nikitin; V. N. Verbetsky

    2011-01-01

    The influence of hydrogenation on the magnetic properties of intermetallic compound RNi is reported. GdNiH3.2, TbNiH3.4, DyNiH3.4 hydrides have been synthesized and their magnetic properties were investigated in the temperature range 1.8–300K. It was established that hydrogen absorption in these compounds makes the ferro- and antiferromagnetic interactions between magnetic moments much weaker. The reasons of this phenomenon are discussed. The

  4. Magnetic properties of the intermetallic compounds RNi (R=Gd, Tb, Dy, Sm) and their hydrides

    Microsoft Academic Search

    Yu. L. Yaropolov; V. N. Verbetsky; A. S. Andreenko; K. O. Berdyshev; S. A. Nikitin

    2010-01-01

    Hydrogen interaction with RNi intermetallic compounds and the influence of hydrogen on magnetic properties of these compounds\\u000a were investigated. Ternary hydrides GdNiH3.2, TbNiH3.4, DyNiH3.4 and SmNiH3.7 were prepared by hydrogenation of the initial alloys at room temperature and hydrogen pressure up to 0.1 MPa. Hydrides possess\\u000a orthorhombic CrB-type structure (S.G. Cmcm). The formation of hydrides results in substantial expansion of

  5. Structure and magnetic properties of hot pressed Dy3-x RxAl2 system (R=Gd and Tb)

    Microsoft Academic Search

    R. T. Obermyer; M. Merches; K. Miller; S. G. Sankar

    1992-01-01

    Dy3-xRxAl2 (R=Gd and Tb) alloys were hot pressed in an inert atmosphere using induction heating in the temperature range 950 to 1000°C and pressures up to 1500 psig. In all cases, with the exception of the spin-only Gd3Al2, preferential magnetic alignment was observed. This was confirmed by X-ray, optical micrography, and magnetic measurements on samples both parallel and perpendicular to

  6. Investigations on magnetic refrigeration: Application to RNi2 (R=Nd, Gd, Tb, Dy, Ho, and Er)

    NASA Astrophysics Data System (ADS)

    von Ranke, P. J.; Grangeia, Daniel F.; Caldas, A.; de Oliveira, N. A.

    2003-04-01

    In this article we report the thermodynamic investigations on the Ericsson cycle with application on RNi2 (R=Nd, Gd, Tb, Dy, Ho, and Er) series. Besides the Zeeman and exchange interactions, these compounds present an important contribution from crystalline electrical field interaction. The Ericsson coefficient of performance and refrigerant capacity was investigated under the crystal field influence. An optimum molar composite of Er-Dy-TbNi2 was proposed to work as refrigerant material in the temperature interval from 7 to 22 K.

  7. Temperature dependent EUV spectra of Gd, Tb and Dy ions observed in the Large Helical Device

    NASA Astrophysics Data System (ADS)

    Suzuki, C.; Koike, F.; Murakami, I.; Tamura, N.; Sudo, S.

    2015-07-01

    We have observed a number of different types of extreme ultraviolet (EUV) spectra from highly charged gadolinium (Gd), terbium (Tb) and dysprosium (Dy) ions in optically thin plasmas produced in the Large Helical Device at the National Institute for Fusion Science. Temporal changes in EUV spectra in the 6–9 nm region subsequent to the injections of solid pellets were measured by a grazing incidence spectrometer. The spectra rapidly change from discrete features into unresolved transition arrays (UTAs) following a drop in the electron temperature after the heating power is reduced. In particular, extremely narrowed UTA features, which comprise spectral lines of Ag-like, Pd-like and neighboring ion stages, are observed when the peak electron temperature is less than 0.45 keV due to the formation of hollow plasmas. Some discrete spectral lines of Cu-like and Ag-like ions have been identified in the high and low temperature plasmas, respectively, some of which are experimentally identified for the first time.

  8. Photoluminescence properties of RE 3+-activated Na 3GdP 2O 8 (RE 3+ = Tb 3+, Dy 3+, Eu 3+, Sm 3+) under VUV excitation

    Microsoft Academic Search

    Feng Zhang; Yuhua Wang; Yan Wen; Dan Wang; Ye Tao

    2011-01-01

    RE3+-activated monoclinic Na3GdP2O8 (RE3+=Tb3+, Dy3+, Eu3+, Sm3+) phosphors have been synthesized by a solid-state reaction method. Their photoluminescence properties in the vacuum ultraviolet (VUV) region were investigated. By analyzing their excitation spectra, the host-related absorption band was determined to be around 166nm. The f–d transition bands and the charge transfer bands for Na3GdP2O8:RE3+ (RE3+=Tb3+, Dy3+, Eu3+, Sm3+) were assigned and

  9. Anomalous pressure dependence of magnetic ordering temperature in Tb revealed by resistivity measurements to 141 GPa: Comparison with Gd and Dy

    NASA Astrophysics Data System (ADS)

    Lim, J.; Fabbris, G.; Haskel, D.; Schilling, J. S.

    2015-05-01

    In previous studies, the pressure dependence of the magnetic ordering temperature To of Dy was found to exhibit a sharp increase above its volume collapse pressure of 73 GPa, appearing to reach temperatures well above ambient at 157 GPa. In a search for a second such lanthanide, electrical resistivity measurements were carried out on neighboring Tb to 141 GPa over the temperature range 3.8-295 K. Below Tb's volume collapse pressure of 53 GPa, the pressure dependence To(P ) mirrors that of both Dy and Gd. However, at higher pressures To(P ) for Tb becomes highly anomalous. This result, together with the very strong suppression of superconductivity by dilute Tb ions in Y, suggests that extreme pressure transports Tb into an unconventional magnetic state with an anomalously high magnetic ordering temperature.

  10. Pressure dependence of the charge-density-wave and superconducting states in GdTe3, TbTe3, and DyTe3

    NASA Astrophysics Data System (ADS)

    Zocco, D. A.; Hamlin, J. J.; Grube, K.; Chu, J.-H.; Kuo, H.-H.; Fisher, I. R.; Maple, M. B.

    2015-05-01

    We present electrical resistivity and ac-susceptibility measurements of GdTe3, TbTe3, and DyTe3 performed under pressure. An upper charge-density-wave (CDW) is suppressed at a rate of d TCDW ,1/d P ˜-85 K /GPa . For TbTe3 and DyTe3, a second CDW below TCDW ,2 increases with pressure until it reaches the TCDW ,1(P ) line. For GdTe3, the lower CDW emerges as pressure is increased above ˜1 GPa . As these two CDW states are suppressed with pressure, superconductivity (SC) appears in the three compounds at lower temperatures. Ac-susceptibility experiments performed on TbTe3 provide compelling evidence for bulk SC in the low-pressure region of the phase diagram. We provide measurements of superconducting critical fields and discuss the origin of a high-pressure superconducting phase occurring above 5 GPa.

  11. Pechini synthesis of lanthanide (Eu3+/Tb3+or Dy3+) ions activated BaGd2O4 nanostructured phosphors: an approach for tunable emissions.

    PubMed

    Seeta Rama Raju, G; Pavitra, E; Yu, Jae Su

    2014-09-14

    Trivalent lanthanide (Eu(3+), Tb(3+) and Dy(3+)) ions activated tunable color emitting BaGd2O4 (BG) phosphors were synthesized by a facile Pechini-type sol-gel process. The X-ray diffraction pattern confirmed the orthorhombic phase after annealing at 1300 °C for 5 h. Morphological studies were performed based on the analysis of transmission electron microscopy images, which showed needle type nanorods. The BG phosphor exhibited good photoluminescence (PL) properties in the respective regions when doped with Eu(3+), Tb(3+) and Dy(3+) ions. The Eu(3+) co-activated BG:Tb(3+) phosphor yielded tunable emissions including tri-band established white light emission based on the co-activator concentration and excitation wavelength. The energy transfer from Tb(3+) to Eu(3+) ions was controlled by selecting a suitable excitation wavelength and the decay measurements were carried out for analyzing the energy transfer efficiency. The cathodoluminescence properties of these phosphors were almost similar to PL properties when doped with individual Eu(3+), Tb(3+), and Dy(3+) ions, but were different when co-doped with Eu(3+)/Tb(3+) or Eu(3+)/Dy(3+) ions. In the case of Eu(3+)/Tb(3+) doped samples, the energy transfer process occurred unlike the PL channel. The calculated Commission International de l'Eclairage chromaticity coordinates of individual ion doped BG phosphors confirmed red, green, and white emissions and for co-doped samples they showed tunable emission. PMID:25052006

  12. Crystal growth, structure determination, and optical properties of new potassium-rare-earth silicates K 3 RESi 2O 7 ( RE=Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu)

    Microsoft Academic Search

    Ioana Vidican; Mark D. Smith; Hans-Conrad zur Loye

    2003-01-01

    Single crystals of K3RESi2O7 (RE=Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were grown from a potassium fluoride flux. Two different structure types were found for this series. Silicates containing the larger rare earths, RE=Gd, Tb, Dy, Ho, Er, Tm, Yb crystallize in a structure K3RESi2O7 that contains the rare-earth cation in both a slightly distorted octahedral and an ideal

  13. Crystal growth, structure determination, and optical properties of new potassium-rare-earth silicates K3RESi2O7 (RE=Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu)

    Microsoft Academic Search

    Ioana Vidican; Mark D. Smith; Hans-Conrad Zur Loye

    2003-01-01

    Single crystals of K3RESi2O7 (RE=Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were grown from a potassium fluoride flux. Two different structure types were found for this series. Silicates containing the larger rare earths, RE=Gd, Tb, Dy, Ho, Er, Tm, Yb crystallize in a structure K3RESi2O7 that contains the rare-earth cation in both a slightly distorted octahedral and an ideal

  14. Magnetic properties of the charge density wave compounds RTe3 (R=Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm)

    E-print Network

    Fisher, Ian

    Magnetic properties of the charge density wave compounds RTe3 (R=Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy July 2008 The antiferromagnetic transition is investigated in the rare-earth R tritelluride RTe3 family structure. DOI: 10.1103/PhysRevB.78.012410 PACS number s : 71.45.Lr, 72.15. v, 75.50.Ee The RTe3 family

  15. Syntheses, Thermal Stability, and Structure Determination of the Novel Isostructural RBa3B9O18 (R ) Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er,

    E-print Network

    Wang, Wei Hua

    interest as universal hosts of the luminescent materials for tricolor lamps. Consequently, the structure ) Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb) X. Z. Li, C. Wang, X. L. Chen,*, H. Li, L. S. Jia, L an analogue structure of -BaB2O4. A series of isostructural borate compounds RBa3B9O18 (R ) Y, Pr, Nd, Sm, Eu

  16. Synthesis, structure, and magnetic properties of Dy?Co?L??(bipy)? and Ln?Ni?L??(bipy)?, Ln = La, Gd, Tb, Dy, and Ho: slow magnetic relaxation in Dy?Co?L??(bipy)? and Dy?Ni?L??(bipy)?.

    PubMed

    Zhao, Fang-Hua; Li, Hui; Che, Yun-Xia; Zheng, Ji-Min; Vieru, Veacheslav; Chibotaru, Liviu F; Grandjean, Fernande; Long, Gary J

    2014-09-15

    The 3,5-dichlorobenzoate anion, L(-), serves as a bridging ligand and 2,2'-bipyridine, bipy, as a terminal bidentate ligand to yield, through hydrothermal syntheses, the tetranuclear clusters Dy2Co2L10(bipy)2, 1, and Ln2Ni2L10(bipy)2, where Ln is the trivalent La, 2, Gd, 3, Tb, 4, Dy, 5, or Ho, 6, ion. Single-crystal X-ray diffraction reveals that the six complexes are all isomorphous with the monoclinic P2?/c space group and with lattice parameters that decrease with the lanthanide contraction. The two cobalt(II) or nickel(II) and two Ln(III) cations are linked by the 10 L(-) anions to generate Dy2Co2 or Ln2Ni2 3d-4f cationic heteronuclear clusters with a slightly bent Co···Dy···Dy···Co or Ni···Ln···Ln···Ni arrangement. Direct current magnetic susceptibility studies reveal that the complexes are essentially paramagnetic, with room-temperature ?(M)T values close to the expected values for two cobalt(II) or nickel(II) and two Ln(III) cations. The temperature dependence of ?(M)T for 1 and 5 is well reproduced by ab initio calculations with the inclusion of weak magnetic exchange between the cobalt(II) or nickel(II) and a dysprosium(III) and between two dysprosium(III) ions. The calculated magnetic exchange parameters are J(Dy-Co) = 0.2 cm(-1) and J(Dy-Dy) = 0.02 cm(-1) for 1 and J(Dy-Ni) = -0.2 cm(-1) and J(Dy-Dy) = 0.03 cm(-1) for 5. Alternating current magnetic susceptibility studies reveal that 1 and 5 exhibit slow magnetic relaxation with effective energy barriers, Ueff, for the reversal of the magnetization for 1 of 82(2) cm(-1) in a 0 Oe dc bias field and 79.4(5) cm(-1) in a 1000 Oe dc bias field and, for 5, 73(1) cm(-1) in a 0 dc bias field; the calculated energies of 66.1(1) and 61.0(1) cm(-1) for the first excited spin-orbit state of dysprosium(III) in 1 and 5 agree rather well with these effective energy barriers. The entire Arrhenius plots of the logarithm of ?, the relaxation rate of the magnetization in 1 and 5, have been fit with contributions from quantum tunneling, direct Raman scattering, and Orbach thermal processes. The observation of a low-temperature magnetization reversal mechanism in 5 but not in 1 may be understood through the calculated exchange energy spectrum in their ground state. PMID:25170649

  17. Highly uniform and monodisperse GdOF:Ln3+ (Ln = Eu, Tb, Tm, Dy, Ho, Sm) microspheres: hydrothermal synthesis and tunable-luminescence properties.

    PubMed

    Zhang, Yang; Kang, Xiaojiao; Geng, Dongling; Shang, Mengmeng; Wu, Yuan; Li, Xuejiao; Lian, Hongzhou; Cheng, Ziyong; Lin, Jun

    2013-10-21

    GdOF:Ln(3+) (Ln = Eu, Tb, Tm, Dy, Ho and Sm) microspheres (1.5 ?m) with high uniformity and monodispersity have been synthesized via a facile hydrothermal method followed by heat treatment (600 °C). X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), as well as photoluminescence (PL) and cathodoluminescence (CL) spectra are used to characterize the resulting samples. A series of controlled experiments indicate that sodium citrate (Cit(3-)) as a shape modifier introduced into the reaction system plays a critical role in the shape evolution of the final products. Furthermore, the shape and size of the products can be further manipulated by adjusting the dosage of Cit(3-) and pH values in the initial solution. The possible formation mechanism for these microspheres has been presented. Under UV light and low-voltage electron beam excitation, GdOF:Ln(3+) microspheres show the characteristic f-f transitions of Ln(3+) (Eu, Tb/Ho, Tm, Dy and Sm) ions and give bright red, green, blue, yellow and yellowish-orange emission, respectively. In addition, multicolored luminescence containing white emission have been successfully confected for co-doped GdOF:Ln(3+) phosphors by changing the doped Ln(3+) ions and adjusting their doping concentrations due to the simultaneous luminescence of Ln(3+) in the GdOF host, making these materials have potential applications in field-emission display devices. PMID:23942823

  18. Crystal chemistry of the orthorhombic Ln2TiO5 compounds with Ln=La, Pr, Nd, Sm, Gd, Tb and Dy

    NASA Astrophysics Data System (ADS)

    Aughterson, Robert D.; Lumpkin, Gregory R.; Thorogood, Gordon J.; Zhang, Zhaoming; Gault, Baptiste; Cairney, Julie M.

    2015-07-01

    The crystal structures of seven samples of orthorhombic (Pnma) Ln2TiO5 compounds with Ln=La, Pr, Nd, Sm, Gd, Tb and Dy were refined by Rietveld analysis of synchrotron X-ray powder diffraction (S-XRD) data. With increasing size of the lanthanide cation, the lattice parameters increase systematically: c by only ~1.5% whereas both a and b by ~6% from Dy2TiO5 to La2TiO5. The mean Ti-O bond length only increases by ~1% with increasing radius of the Ln cation from Gd to La, primarily due to expansion of the pair of Ti-O3 bonds to opposite corners of the Ti-O5 square based pyramid polyhedra. For Dy2TiO5 and Tb2TiO5, a significant variation in Ti-O1 and Ti-O4 bond lengths results in an increased deformation of the Ti-O5 base. The particular configuration consists of large rhombic shaped tunnels and smaller triangular tunnels along the b axis, which have implications for defect formation and migration caused by radiation damage or the ionic conductivity.

  19. Family of defect-dicubane Ni4Ln2 (Ln = Gd, Tb, Dy, Ho) and Ni4Y2 complexes: rare Tb(III) and Ho(III) examples showing SMM behavior.

    PubMed

    Zhao, Lang; Wu, Jianfeng; Ke, Hongshan; Tang, Jinkui

    2014-04-01

    Reactions of Ln(III) perchlorate (Ln = Gd, Tb, Dy, and Ho), NiCl2·6H2O, and a polydentate Schiff base resulted in the assembly of novel isostructural hexanuclear Ni4Ln2 complexes [Ln = Gd (1), Tb (2), Dy (3), Ho (4)] with an unprecedented 3d-4f metal topology consisting of two defect-dicubane units. The corresponding Ni4Y2 (5) complex containing diamagnetic Y(III) atoms was also isolated to assist the magnetic studies. Interestingly, complexes 2 and 3 exhibit SMM characteristics and 4 shows slow relaxation of the magnetization. The absence of frequency-dependent in-phase and out-of-phase signals for the Ni-Y species suggests that the Ln ions' contribution to the slow relaxation must be effectual as previously observed in other Ni-Dy samples. However, the observation of ?? signals with zero dc field for the Ni-Tb and Ni-Ho derivatives is notable. Indeed, this is the first time that such a behavior is observed in the Ni-Tb and Ni-Ho complexes. PMID:24661008

  20. Rare earth-nickel-indides Dy{sub 5}Ni{sub 2}In{sub 4} and RE{sub 4}Ni{sub 11}In{sub 20} (RE=Gd, Tb, Dy)

    SciTech Connect

    Tyvanchuk, Yuriy B. [Inorganic Chemistry Department, Ivan Franko National University of Lviv, Kyryla and Mephodiya Street 6, 79005 Lviv (Ukraine); Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster, Corrensstrasse 30, 48149 Muenster (Germany)], E-mail: yutyv@franko.lviv.ua; Rodewald, Ute Ch. [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster, Corrensstrasse 30, 48149 Muenster (Germany); Kalychak, Yaroslav M. [Inorganic Chemistry Department, Ivan Franko National University of Lviv, Kyryla and Mephodiya Street 6, 79005 Lviv (Ukraine); Poettgen, Rainer [Inorganic Chemistry Department, Ivan Franko National University of Lviv, Kyryla and Mephodiya Street 6, 79005 Lviv (Ukraine)], E-mail: pottgen@uni-muenster.de

    2008-04-15

    The new rare earth metal (RE)-nickel-indides Dy{sub 5}Ni{sub 2}In{sub 4} and RE{sub 4}Ni{sub 11}In{sub 20} (RE=Gd, Tb, Dy) were synthesized from the elements by arc-melting. Well-shaped single crystals were obtained by special annealing sequences. The four indides were investigated by X-ray diffraction on powders and single crystals: Lu{sub 5}Ni{sub 2}In{sub 4} type, Pbam, Z=2, a=1784.2(8), b=787.7(3), c=359.9(1) pm, wR{sub 2}=0.0458, 891 F{sup 2} values, 36 variables for Dy{sub 5}Ni{sub 2}In{sub 4}, U{sub 4}Ni{sub 11}Ga{sub 20} type, C2/m, a=2254.0(9), b=433.8(3), c=1658.5(8) pm, {beta}=124.59(2){sup o}, wR{sub 2}=0.0794, 2154 F{sup 2} values, 108 variables for Gd{sub 4}Ni{sub 11}In{sub 20}, a=2249.9(8), b=432.2(1), c=1657.9(5) pm, {beta}=124.59(2){sup o}, wR{sub 2}=0.0417, 2147 F{sup 2} values, 108 variables for Tb{sub 4}Ni{sub 11}In{sub 20}, and a=2252.2(5), b=430.6(1), c=1659.7(5) pm, {beta}=124.58(2){sup o}, wR{sub 2}=0.0550, 2003 F{sup 2} values, 109 variables for Dy{sub 4}Ni{sub 10.80}In{sub 20.20}. The 2d site in the dysprosium compound shows mixed Ni/In occupancy. Most nickel atoms in both series of compounds exhibit trigonal prismatic coordination by indium and rare earth atoms. Additionally, in the RE{sub 4}Ni{sub 11}In{sub 20} compounds one observes one-dimensional nickel clusters (259 pm Ni{sub 1}-Ni{sub 6} in Dy{sub 4}Ni{sub 10.80}In{sub 20.20}) that are embedded in an indium matrix. While only one short In{sub 1}-In{sub 2} contact at 324 pm is observed in Dy{sub 5}Ni{sub 2}In{sub 4}, the more indium-rich Dy{sub 4}Ni{sub 10.80}In{sub 20.20} structure exhibits a broader range in In-In interactions (291-364 pm). Together the nickel and indium atoms build up polyanionic networks, a two-dimensional one in Dy{sub 5}Ni{sub 2}In{sub 4} and a complex three-dimensional network in Dy{sub 4}Ni{sub 10.80}In{sub 20.20}. These features have a clear consequence on the dysprosium coordination, i.e. a variety of short Dy-Dy contacts (338-379 pm) in Dy{sub 5}Ni{sub 2}In{sub 4}, while the dysprosium atoms are well separated (430 pm shortest Dy-Dy distance) within the distorted hexagonal channels of the [Ni{sub 10.80}In{sub 20.20}] polyanion of Dy{sub 4}Ni{sub 10.80}In{sub 20.20}. The crystal chemistry of both structure types is comparatively discussed. - Graphical abstract: Crystal structure of Dy{sub 5}Ni{sub 2}In{sub 4}.

  1. Tunnel-diode Resonator Spectroscopy of Quantum Levels in Cr12 Ln 4 (Ln=Y,Eu,Gd,Tb,Dy,Ho,Yb) Magnetic Molecules

    NASA Astrophysics Data System (ADS)

    Yeninas, Steven; Luban, Marshall; Prozorov, Ruslan; Coniglio, William A.; Agosta, Charles C.; Engelhardt, Larry; Timco, Grigore A.; Winnpenny, Richard E. P.

    2011-03-01

    The differential magnetic susceptibility for a series of Cr 12 Ln 4 (Ln=Y,Eu,Gd,Tb,Dy,Ho,Yb) magnetic molecules was measured in static (up to 16 T) and pulsed (up to 45 T) magnetic fields using a rf tunnel-diode resonator (TDR). At low temperatures, the behavior of these finite spin systems is governed by discrete energy spectra of the individual molecules. In magnetic field, low-energy quantum levels Zeeman-split, crossing at field values where magnetization exhibits a step corresponding to switching between different spin states. In high fields, we detect multiple level crossings which allow for a detailed mapping of the energy diagram. We then perform quantum Monte Carlo (QMC) using a Heisenberg Hamiltonian with three adjustable exchange constants whose values are chosen so as to optimize agreement with the experimental energy spectrum. The variations in results for the studied molecules are correlated to the magnetic properties of the lanthanide ions.

  2. Angle-resolved photoemission study of the evolution of band structure and charge density wave properties in RTe3 (R=Y, La, Ce, Sm, Gd, Tb, and Dy)

    E-print Network

    Fisher, Ian

    properties in RTe3 (R=Y, La, Ce, Sm, Gd, Tb, and Dy) V. Brouet,1,2,3 W. L. Yang,2,3 X. J. Zhou,2,3 Z. Hussain a detailed angle-resolved photoemission spectroscopy ARPES investigation of the RTe3 family, which sets unique ability to resolve the electronic structure in k space. An additional advantage of RTe3

  3. Heat capacity of RFexMn12-x (R = Gd, Tb and Dy) compounds: wiping out a cooperative 4f 4f exchange interaction by breaking the 3d 4f magnetic symmetry

    Microsoft Academic Search

    C. Piqué; J. A. Blanco; R. Burriel; E. Abad; J. Fernández-Rodríguez; M. Artigas

    2008-01-01

    Using adiabatic calorimetry the heat capacity of a series of RFexMn12-x (R = Gd, Tb and Dy) compounds has been measured from 3 to 350 K. The substitution of Fe for Mn in RFexMn12-x influences both the magnetic interactions on the 3d sublattice and the magnetism of R (the Néel temperature doubles on going from x = 0 to 6

  4. RE2MAl6Si4 (RE = Gd, Tb, Dy; M = Au, Pt): layered quaternary intermetallics featuring CaAl2Si2-type and YNiAl4Ge2-type slabs grown from aluminum flux.

    PubMed

    Latturner, Susan E; Bilc, Daniel; Mahanti, S D; Kanatzidis, Mercouri G

    2003-12-01

    Six new intermetallic aluminum silicides--Gd(2)PtAl(6)Si(4), Gd(2)AuAl(6)Si(4), Tb(2)PtAl(6)Si(4), Tb(2)AuAl(6)Si(4), Dy(2)PtAl(6)Si(4), and Dy(2)AuAl(6)Si(4)--have been obtained from reactions carried out in aluminum flux. The structure of these compounds was determined by single-crystal X-ray diffraction. They form in space group Rthremacr;m with cell constants of a = 4.1623(3) A and c = 51.048(5) A for the Gd(2)PtAl(6)Si(4) compound. The crystal structure is comprised of hexagonal nets of rare earth atoms alternating with two kinds of layers that have been observed in other multinary aluminide intermetallic compounds (CaAl(2)Si(2) and YNiAl(4)Ge(2)). All six RE(2)MAl(6)Si(4) compounds show antiferromagnetic transitions at low temperatures (T(N) < 20 K); magnetization studies of the Dy compounds show metamagnetic behavior with reorientation of spins at 6000 G. Band structure calculations indicate that the AlSi puckered hexagonal sheets in this structure are electronically distinct from the other surrounding structural motifs. PMID:14632514

  5. LETTER TO THE EDITOR: Magnetic entropy change in RCoAl (R = Gd, Tb, Dy, and Ho) compounds: candidate materials for providing magnetic refrigeration in the temperature range 10 K to 100 K

    NASA Astrophysics Data System (ADS)

    Zhang, X. X.; Wang, F. W.; Wen, G. H.

    2001-08-01

    Large magnetic entropy changes were observed in RCoAl compounds, where R = Gd, Tb, Dy, and Ho, at their Curie temperatures. These RCoAl alloys have a hexagonal, MgZn2 structure and their Curie temperatures fall in the temperature range 10-100 K. A `table-like' behaviour was found in the temperature dependence of the magnetic entropy change (-?S(T)) obtained in the soft magnetic GdCoAl alloys, which can be used either to fill up the gap (near 100 K) in the profile of magnetic entropy change versus temperature required by an eight-stage magnetic refrigerator or to complete an Ericsson circle. It has also been shown that soft ferromagnetic materials with Curie temperatures in the temperature range from 10 K to 100 K can be obtained by using multi-R elements instead of a single-R element in the RCoAl compounds.

  6. Srystal structure and physical properties of the new ternary antimonides Ln{sub 3}Pd{sub 8}Sb{sub 4} (Ln=Y, Gd, Tb, Dy, Ho, Er, Tm)

    SciTech Connect

    Zelinska, Mariya [Department of Analytical Chemistry, Ivan Franko National University of Lviv, Kyryla and Mefodija Str. 6, 79005 Lviv (Ukraine); Sciences Chimiques de Rennes, UMR CNRS 6226, Universite de Rennes 1 - ENSCR, Campus de Beaulieu, Avenue du General Leclerc, 35042 Rennes Cedex (France); Oryshchyn, Stepan; Zhak, Olga [Department of Analytical Chemistry, Ivan Franko National University of Lviv, Kyryla and Mefodija Str. 6, 79005 Lviv (Ukraine); Pivan, Jean-Yves; Potel, Michel; Tougait, Olivier; Noel, Henri [Sciences Chimiques de Rennes, UMR CNRS 6226, Universite de Rennes 1 - ENSCR, Campus de Beaulieu, Avenue du General Leclerc, 35042 Rennes Cedex (France); Kaczorowski, Dariusz, E-mail: D.Kaczorowski@int.pan.wroc.p [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw (Poland)

    2010-09-15

    The ternary antimonides Ln{sub 3}Pd{sub 8}Sb{sub 4} (Ln=Y, Gd, Tb, Dy, Ho, Er, Tm) have been synthesized for the first time. The crystal structure of Er{sub 3}Pd{sub 8}Sb{sub 4} has been solved from the X-ray single crystal data: own type structure, space group Fm3-bar m, a=1.3050(1) nm, R{sub F}=0.0484, R{sub W}=0.0524 for 17 free parameters and 401 reflections with F(hkl)>4{sigma}(F). The structure of Er{sub 3}Pd{sub 8}Sb{sub 4} can be viewed as a ternary ordered version of the Sc{sub 11}Ir{sub 4}-type. The lattice parameters of the isotypic compounds Ln{sub 3}Pd{sub 8}Sb{sub 4} (Ln=Y, Gd, Tb, Dy, Ho, Tm) have been refined from the X-ray powder diffraction data. The magnetic and electrical properties of the compounds Ln{sub 3}Pd{sub 8}Sb{sub 4} (Ln=Tb, Ho, Er) have been studied down to 1.75 K. The Ho- and Er-based phases have been found to order antiferromagnetically at 2.5 and 2.0 K, respectively. For all three compounds, the magnetic susceptibility follows in the paramagnetic region the Curie-Weiss behavior with the effective magnetic moments close to the respective free trivalent ion values. All three antimonides studied exhibit metallic character of the electrical conductivity. - Graphical abstract: Projection of the crystal structure of Er{sub 3}Pd{sub 8}Sb{sub 4} onto XY plane and the coordination polyhedra of all the atoms.

  7. The effect of hybridization on local magnetic interactions at highly diluted Ce ions in tetragonal intermetallic compounds RERh2Si2 (RE=Ce, Pr, Nd, Gd, Tb, Dy)

    NASA Astrophysics Data System (ADS)

    Cabrera-Pasca, G. A.; Carbonari, A. W.; Bosch-Santos, B.; Mestnik-Filho, J.; Saxena, R. N.

    2012-10-01

    The contribution of the 4f electron to the local magnetic field at highly diluted Ce atoms in RERh2Si2 (RE = Ce, Pr, Nd, Gd, Tb, Dy) has been investigated as a function of temperature through the measurement of the magnetic hyperfine field in 140Ce nuclei by time differential perturbed gamma-gamma angular correlation spectroscopy. Samples of the studied compounds were characterized by x-ray diffraction and zero-field resistance to determine the crystal structure and transport properties. DC magnetic susceptibility was measured for NdRh2Si2. It was observed that the variation of the magnetic hyperfine field with temperature follows the expected behaviour for the host magnetization, with the exception of GdRh2Si2, which showed a strong deviation from such a behaviour. It is shown that the hybridization of the d band of the host with the f band of the Ce impurity, which is stronger in GdRh2Si2 than in other compounds, is responsible for the observed deviation from the expected temperature dependence of the hyperfine field. The origin of this stronger hybridization is ascribed to the relatively small magnetic anisotropy observed in GdRh2Si2 when compared with the other compounds of the series, as shown by resistance measurements.

  8. Heat capacity of RFexMn12-x (R = Gd, Tb and Dy) compounds: wiping out a cooperative 4f 4f exchange interaction by breaking the 3d 4f magnetic symmetry

    NASA Astrophysics Data System (ADS)

    Piqué, C.; Blanco, J. A.; Burriel, R.; Abad, E.; Fernández-Rodríguez, J.; Artigas, M.

    2008-08-01

    Using adiabatic calorimetry the heat capacity of a series of RFexMn12-x (R = Gd, Tb and Dy) compounds has been measured from 3 to 350 K. The substitution of Fe for Mn in RFexMn12-x influences both the magnetic interactions on the 3d sublattice and the magnetism of R (the Néel temperature doubles on going from x = 0 to 6 and the compounds become ferromagnetic for x = 8 with Curie temperatures of around 300 K). In pure TbMn12 the heat-capacity data shows a ?-type anomaly associated with the independent cooperative magnetic ordering of the R sublattice (~5 K), while the anomaly related to the Mn magnetic ordering (~100 K) is rather smooth, as observed in other itinerant magnetic systems such as YMn12. In contrast, the substitution of Fe for Mn leads, on the one hand, to a more localized magnetic behaviour of the 3d sublattice, and, on the other, to magnetic polarization effects between the 3d and 4f sublattices, together with the disappearance of the cooperative magnetic ordering of the R sublattice due to the breaking of the antiferromagnetic symmetry in the 3d sublattice. This is reflected in the heat-capacity curve through a smooth Schottky-like anomaly. In the case of Gd compounds the magnitude of the exchange molecular-field parameter has been deduced by fitting the magnetic contribution to the heat capacity within a simple mean-field model. From this analysis we found that this molecular field acting on the rare-earth site increases with the iron concentration, reaching values as large as 48 T for the concentration x = 6. A similar analysis of the heat capacity in the ordered phase on the Tb compounds also leads to an enhancement of the molecular field with increasing Fe content. These results allow checking the possible crystal-field parameters for these RFexMn12-x compounds.

  9. Magnetic and electrical transport properties of orthocobaltites R0.5Ba0.5CoO3 (R=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy)

    NASA Astrophysics Data System (ADS)

    Troyanchuk, I. O.; Kasper, N. V.; Khalyavin, D. D.; Szymczak, H.; Szymczak, R.; Baran, M.

    1998-08-01

    Magnetization and electrical resistivity studies have established that La0.5Ba0.5CoO3-? (LaBaC) is a metallic ferromagnet whereas Pr0.5Ba0.5CoO3-? (PrBaC) is a magnetic semiconductor. The magnitudes of spontaneous magnetizations are in agreement with intermediate (LaBaC) and low-spin (PrBaC) cobalt states with itinerant 3d electrons. R0.5Ba0.5CoO3-? (RBaC, R=Sm, Eu, Gd, Tb, Dy) exhibit a sequence of a phase transitions at temperatures Ti, TC, and TM on heating. Below Ti these materials are antiferromagnets, whereas in the temperature interval between Ti and TC, a ferromagnetic behavior has been revealed. For TbBaC the temperatures Ti and TC are 245 and 285 K, respectively. The phase transition at Ti is accompanied by a jump of electrical resistivity and peak of magnetoresistance. For TbBaC an external magnetic field of 14 T leads to decreasing Ti from 245 to 85 K. At around TM (337 K for TbBaC) the first-order phase transition from semiconductive to quasimetallic state (high-temperature phase) has been observed. The transition occurs without changes of orthorhombic symmetry, and the unit-cell volume of the high-temperature phase was shown to be larger as compared to the low-temperature one (approximately 0.2%). It is supposed that the transition at TM results from oxygen vacancy ordering.

  10. Syntheses, structure and rare earth metal photoluminescence of new and known isostructural A{sub 2}Mo{sub 4}Sb{sub 2}O{sub 18} (A=Ce, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) compounds

    SciTech Connect

    Mohitkar, Shrikant A.; Kalpana, G. [Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036 (India); Vidyasagar, K., E-mail: kvsagar@iitm.ac.i [Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036 (India)

    2011-04-15

    Nine new A{sub 2}Mo{sub 4}Sb{sub 2}O{sub 18} (A=Ce, Pr, Eu, Tb, Ho, Er, Tm, Yb, Lu) compounds have been synthesized by solid-state reactions. They are isostructural with six reported analogues of yttrium and other lanthanides and the monoclinic unit cell parameters of all fifteen of them vary linearly with the size of A{sup 3+} ion. Single crystal X-ray structures of eight A{sub 2}Mo{sub 4}Sb{sub 2}O{sub 18} (A=Ce, Pr, Eu, Gd, Tb, Ho, Er, Tm) compounds have been determined. Neat A{sub 2}Mo{sub 4}Sb{sub 2}O{sub 18} (A=Pr, Sm, Eu, Tb, Dy, Ho, Er, Tm) compounds exhibit characteristic rare earth metal photoluminescence. -- Graphical abstract: Among the fifteen isostructural A{sub 2}Mo{sub 4}Sb{sub 2}O{sub 18} (A=rare earth metal) molybdoantimonites, eight (A=Pr, Sm, Eu, Tb, Dy, Ho, Er, Tm) compounds exhibit neat characteristic lanthanide photoluminescence in the 200-800 nm range at room temperature. Display Omitted Research highlights: {yields} Syntheses of nine new A{sub 2}Mo{sub 4}Sb{sub 2}O{sub 18} (A=Ce, Pr, Eu, Tb, Ho, Er, Tm, Yb, Lu) compounds. {yields} X-ray structures of eight A{sub 2}Mo{sub 4}Sb{sub 2}O{sub 18} (A=Ce, Pr, Eu, Gd, Tb, Ho, Er, Tm) compounds. {yields} Photoluminescence of neat A{sub 2}Mo{sub 4}Sb{sub 2}O{sub 18} (A=Pr, Sm, Eu, Tb, Dy, Ho, Er, Tm) compounds.

  11. Magnetic properties of the charge density wave compounds RTe3, R=Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er & Tm

    SciTech Connect

    Ru, N.; Chu, J.-H.; Fisher, I.R.; /Stanford U., Geballe Lab.

    2009-12-14

    The antiferromagnetic transition is investigated in the rare-earth (R) tritelluride RTe{sub 3} family of charge density wave (CDW) compounds via specific heat, magnetization and resistivity measurements. Observation of the opening of a superzone gap in the resistivity of DyTe{sub 3} indicates that additional nesting of the reconstructed Fermi surface in the CDW state plays an important role in determining the magnetic structure.

  12. Synthesis, structural characterization and Mössbauer study of LnV{sub 0.5}Fe{sub 0.5}O{sub 3} perovskites (Ln = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho and Er)

    SciTech Connect

    Ivashita, Flávio F.; Biondo, Valdecir; Bellini, Jusmar V.; Paesano, Andrea [Departamento de Física, Universidade Estadual de Maringá, Av. Colombo 5790, 87.020-900 Maringá, PR (Brazil)] [Departamento de Física, Universidade Estadual de Maringá, Av. Colombo 5790, 87.020-900 Maringá, PR (Brazil); Blanco, M. Cecilia; Fuertes, Valeria C.; Pannunzio-Miner, Elisa V. [INFIQC-CONICET, Departamento de Fisicoquímica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA Córdoba (Argentina)] [INFIQC-CONICET, Departamento de Fisicoquímica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA Córdoba (Argentina); Carbonio, Raúl E., E-mail: carbonio@fcq.unc.edu.ar [INFIQC-CONICET, Departamento de Fisicoquímica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA Córdoba (Argentina)

    2012-09-15

    Graphical abstract: Mössbauer spectra taken at 200 K for the Y(V{sub 0.5}Fe{sub 0.5})O{sub 3} orthoferrivanadate synthesized by arc-melting. Highlights: ? LnFe{sub 0.5}V{sub 0.5}O{sub 3} were synthesized by the first time for most of the rare-earth elements. ? These orthoferrivanadates crystallize metastably with the perovskite structure. ? Iron and vanadium are trivalent stabilized in these solid solutions. ? The Mössbauer quadrupolar splitting is correlated with the tolerance factor. ? Below 100 K, these perovskites undergo a crystallographic phase transformation. -- Abstract: Perovskites LnV{sub 0.5}Fe{sub 0.5}O{sub 3} (Ln = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho and Er) were synthesized by rapid solidification from arc-melted samples and characterized by the study of their crystal structure and hyperfine properties. These metastable solid solutions crystallized in the Pbnm symmetry, with the iron and vanadium cations randomly distributed in the transition metal octahedral sites. Depending on the lanthanide present at the A site of the perovskite, iron is present with two valences (i.e., Fe{sup 3+} and Fe{sup 2+}). The volume of the unit cell for these perovskites increases linearly with the lanthanide ionic radius, as the perovskite approaches its ideal structure. At room temperature, the quadrupolar splitting of the trivalent paramagnetic Mössbauer component works as an indirect measurement for the Goldshmidt tolerance factor. Close to or below 100 K, these perovskites undergo a crystallographic phase transformation, probably due to orbital ordering of the V{sup 3+} cations, originating two different magnetic iron sites.

  13. ARPES study of the evolution of band structure and charge density wave properties in RTe3 ( R=Y , La, Ce, Sm, Gd, Tb, and Dy)

    SciTech Connect

    Hussain, Zahid; Brouet, Veronique; Yang, Wanli; Zhou, Xingjiang; Hussain, Zahid; Moore, R.G.; He, R.; Lu, D. H.; Shen, Z.X.; Laverock, J.; Dugdale, S.B.; Ru, N.; Fisher, R.

    2008-01-16

    We present a detailed angle-resolved photoemission spectroscopy (ARPES) investigation of the RTe3 family, which sets this system as an ideal"textbook" example for the formation of a nesting driven charge density wave (CDW). This family indeed exhibits the full range of phenomena that can be associated to CDWinstabilities, from the opening of large gaps on the best nested parts of Fermi surface (up to 0.4 eV), to the existence of residual metallic pockets. ARPES is the best suited technique to characterize these features, thanks to its unique ability to resolve the electronic structure in k space. An additional advantage of RTe3 is that theband structure can be very accurately described by a simple two dimensional tight-binding (TB) model, which allows one to understand and easily reproduce many characteristics of the CDW. In this paper, we first establish the main features of the electronic structure by comparing our ARPES measurements with the linear muffin-tinorbital band calculations. We use this to define the validity and limits of the TB model. We then present a complete description of the CDW properties and of their strong evolution as a function of R. Using simple models, we are able to reproduce perfectly the evolution of gaps in k space, the evolution of the CDW wave vector with R, and the shape of the residual metallic pockets. Finally, we give an estimation of the CDWinteraction parameters and find that the change in the electronic density of states n (EF), due to lattice expansion when different R ions are inserted, has the correct order of magnitude to explain the evolution of the CDW properties.

  14. Systematic Study of a Family of Butterfly-Like {M2Ln2} Molecular Magnets (M = Mg(II), Mn(III), Co(II), Ni(II), and Cu(II); Ln = Y(III), Gd(III), Tb(III), Dy(III), Ho(III), and Er(III)).

    PubMed

    Moreno Pineda, Eufemio; Chilton, Nicholas F; Tuna, Floriana; Winpenny, Richard E P; McInnes, Eric J L

    2015-06-15

    A family of 3d-4f [M(II)2Ln(III)2(?3-OH)2(O2C(t)Bu)10](2-) "butterflies" (where M(II) = Mg, Co, Ni, and Cu; Ln(III) = Y, Gd, Tb, Dy, Ho, and Er) and [Mn(III)2Ln(III)2(?3-O)2(O2C(t)Bu)10](2-) molecules (where Ln(III) = Y, Gd, Tb, Dy, Ho, and Er) has been synthesized and characterized through single-crystal X-ray diffraction, SQUID magnetometry, and ab initio calculations. All dysprosium- and some erbium-containing tetramers showed frequency-dependent maxima in the out-of-phase component of the susceptibility associated with slow relaxation of magnetization, and hence, they are single-molecule magnets (SMMs). AC susceptibility measurements have shown that the SMM behavior is entirely intrinsic to the Dy and Er sites and the magnitude of the energy barrier is influenced by the interactions between the 4f and the 3d metal. A trend is observed between the strength of the 3d-4f exchange interaction between and the maximum observed in the ??M(T). PMID:26016421

  15. Synthesis and characterization of monodisperse spherical SiO{sub 2}-RE{sub 2}O{sub 3} (RE=rare earth elements) and SiO{sub 2}-Gd{sub 2}O{sub 3}:Ln{sup 3+} (Ln=Eu, Tb, Dy, Sm, Er, Ho) particles with core-shell structure

    SciTech Connect

    Wang, H.; Yang, J.; Zhang, C.M. [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Lin, J., E-mail: jlin@ciac.jl.c [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2009-10-15

    Spherical SiO{sub 2} particles have been coated with rare earth oxide layers by a Pechini sol-gel process, leading to the formation of core-shell structured SiO{sub 2}-RE{sub 2}O{sub 3} (RE=rare earth elements) and SiO{sub 2}-Gd{sub 2}O{sub 3}:Ln{sup 3+} (Ln=Eu, Tb, Dy, Sm, Er, Ho) particles. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL), and cathodoluminescence spectra as well as lifetimes were used to characterize the resulting SiO{sub 2}-RE{sub 2}O{sub 3} (RE=rare earth elements) and SiO{sub 2}-Gd{sub 2}O{sub 3}:Ln{sup 3+} (Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+}, Sm{sup 3+}, Er{sup 3+}, Ho{sup 3+}) samples. The obtained core-shell phosphors have perfect spherical shape with narrow size distribution (average size ca. 380 nm), smooth surface and non-agglomeration. The thickness of shells could be easily controlled by changing the number of deposition cycles (40 nm for two deposition cycles). Under the excitation of ultraviolet, the Ln{sup 3+} ion mainly shows its characteristic emissions in the core-shell particles from Gd{sub 2}O{sub 3}:Ln{sup 3+} (Eu{sup 3+}, Tb{sup 3+}, Sm{sup 3+}, Dy{sup 3+}, Er{sup 3+}, Ho{sup 3+}) shells. - Graphical abstract: The advantages of core-shell phosphors are the easy availability of homogeneous spherical morphology in different size, and its corresponding luminescence color can change from red, yellow to green.

  16. Sign of canted ferromagnetism in the quasicrystal approximants Au-SM-R (SM = Si, Ge and Sn / R = Tb, Dy and Ho).

    PubMed

    Hiroto, T; Tokiwa, K; Tamura, R

    2014-05-28

    Magnetic susceptibility and magnetization of the quasicrystal approximants Au-SM-R (SM = Si, Ge or Sn / R = Gd, Tb, Dy or Ho) are investigated. Ferromagnetic transitions are observed in all of these compounds, in contrast to the spin-glass behavior reported in similar compounds, Ag-In-R (R = Eu, Gd, Tb or Dy). Au-SM-Gd (SM = Si, Ge or Sn) exhibit a simple ferromagnetic transition at 22.5, 13 and 9?K, respectively, whereas Au-Si-(Tb, Dy or Ho) show indications of a canted ferromagnetic transition at 8.3, 5.9 and 3.8?K, respectively. The latter are attributed to a crystal electric field effect that is absent in the Gd-bearing compounds. The ferromagnetic behavior in Au-SM-R may be understood to be a consequence of the short R-R distances compared to those for Cd-R and Ag-In-R. PMID:24806439

  17. Magnetoelastic vibration damping properties of TbDy alloys

    NASA Technical Reports Server (NTRS)

    Dooley, J. A.; Good, N. R.; White, C. V.; Leland, R. S.

    2002-01-01

    Damping of axial and bending mode vibrations in giant magnetoelastic polycrystalline TbDy alloys was studied at cryogenic temperatures. All specimens of TbDy were arc-melted in the proper composition ratio and dropped into a chilled copper mold. Additional treatments consisted of cold plane-rolling to induce crystallographic texture and then heat-treating to relieve internal stress. Mechanical hysteretic losses were measured at various strains, frequencies, and loading configurations down to 77 K. Both as-cast and textured polycrystalline TbDy samples were tested along with an aluminum specimen for comparison. Loss factors at multiple natural vibration frequencies of the samples were measured for axial modes. Larger damping rates were measured for axial mode vibrations than for bending mode vibrations, possibly reflecting the larger specimen volume contributing to magnetoelastic damping. At LN2 temperatures TbDy materials demonstrated q > 0.05 at 0.01 Hz and q > 0.1 at higher frequencies from 0.6-1.5 kHz.

  18. Synthesis, structure and properties of the oxychalcogenide series A{sub 4}O{sub 4}TiSe{sub 4} (A=Sm, Gd, Tb, Dy, Ho, Er and Y)

    SciTech Connect

    Tuxworth, A.J.; Evans, J.S.O., E-mail: john.evans@durham.ac.uk

    2014-02-15

    Seven oxyselenide materials have been synthesised with composition A{sub 4}O{sub 4}TiSe{sub 4} (A=Sm, Gd–Er, Y) via solid state reactions of A{sub 2}O{sub 3}, TiSe{sub 2} and Se at 900 °C. They are all isostructural with Gd{sub 4}O{sub 4}TiSe{sub 4}. Structures have been refined from powder X-ray diffraction data and have monoclinic C2/m symmetry with unit cell parameters of a?15.7 Å, b?3.75 Å, c?9.65 Å and ??117.5°. They contain infinite ribbons of edge-sharing A{sub 4}O and A{sub 3}TiO tetrahedra 4 units wide, which are linked by chains of TiSe{sub 4}O{sub 2} edge-sharing octahedra. Compositions A=Gd–Ho, Y are semiconductors with conductivities 1–3 Sm{sup ?1} at 300 K, with electronic band gaps of between 0.25 and 0.37 eV. Magnetic susceptibility is reported from 1.8 K to 300 K for compositions A=Gd–Ho. Rare earth moments appear to order antiferromagnetically at low temperatures with Gd and Tb showing evidence of ferromagnetism due to spin canting over a narrow temperature range close to T{sub N}. - Graphical abstract: Illustration of the A{sub 4}O{sub 4}TiSe{sub 4} crystal structure (C2/m symmetry), A{sub 4}O and A{sub 3}TiO edge sharing tetrahedral ribbons in red, chains of edge-sharing TiSe{sub 4}O{sub 2} in blue. Rare earth=green, titanium=blue, selenium=yellow, and oxygen=red. Display Omitted - Highlights: • Seven materials with A{sub 4}O{sub 4}TiSe{sub 4} (A=Sm, Gd–Er, Y) have been synthesised as bulk phases for the first time. • Materials are semiconductors and order antiferromagnetically at ?4 K. • Structure contains M{sub 4}O tetrahedral ribbons and TiSe{sub 4}O{sub 2} 1D octahedral chains.

  19. Lattice dynamics of rare-earth titanates with the structure of pyrochlore R 2Ti2O7 ( R = Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu): Ab initio calculation

    NASA Astrophysics Data System (ADS)

    Chernyshev, V. A.; Petrov, V. P.; Nikiforov, A. E.

    2015-05-01

    The ab initio calculation has been performed for the crystal structure and the phonon spectrum of titanates with the structure of pyrochlore R 2Ti2O7 ( R = Gd-Lu). The frequencies and types of fundamental vibrations have been found. For R = Tb, Tm, and Yb, this calculation has been carried out for the first time; furthermore, there is no available information on experimental studies of the phonon spectrum for Tm and Yb. The influence of hydrostatic pressure to 35 GPa on the structure, dynamics, and elastic properties of the Gd2Ti2O7 lattice has been investigated. The dependence of the phonon frequencies on the pressure has been obtained. The calculations have predicted that the relative change in the pyrochlore structure volume during compression at pressures to 35 GPa is well described by the third-order Birch-Murnaghan equation of states. The results of the calculations agree with the available experimental data. It has been shown that the structural, dynamic, and elastic properties of the R 2Ti2O7 crystal lattice can be adequately described in the case where the inner shells of the RE ion up to 4 f are replaced by the pseudopotential.

  20. High pressure synthesis of late rare earth RFeAs(O,F) superconductors; R = Tb and Dy.

    PubMed

    Bos, Jan-Willem G; Penny, George B S; Rodgers, Jennifer A; Sokolov, Dmitry A; Huxley, Andrew D; Attfield, J Paul

    2008-08-21

    New TbFeAs(O,F) and DyFeAs(O,F) superconductors with critical temperatures T(c) = 46 and 45 K and very high critical fields, >or=100 T, have been prepared at 1100-1150 degrees C and 10-12 GPa, demonstrating that high pressure may be used to synthesise late rare earth derivatives of the recently reported RFeAs(O,F) (R = La-Nd, Sm, Gd) high temperature superconductors. PMID:18665282

  1. Luminescent properties of Tb3+ and Gd3+ ions doped aluminosilicate oxyfluoride glasses.

    PubMed

    Zuo, Chenggang; Lu, Anxian; Zhu, Ligang; Zhou, Zhihua; Long, Woyun

    2011-11-01

    Tb(3+) and Gd(3+) ions doped lithium-barium-aluminosilicate oxyfluoride glasses have been prepared. The transmission, emission and excitation spectra were measured. It has been found that those Tb(3+)-doped lithium-barium-aluminosilicate oxyfluoride glasses exhibit good UV-excited luminescence. The luminescence intensity of Tb(3+) ion increases for those (Tb(3+), Gd(3+))-codoped glasses. Energy transfer process from Gd(3+) ion to Tb(3+) ion is indicated. PMID:21831699

  2. Yellow laser performance of Dy³? in co-doped Dy,Tb:LiLuF?.

    PubMed

    Bolognesi, Giacomo; Parisi, Daniela; Calonico, Davide; Costanzo, Giovanni Antonio; Levi, Filippo; Metz, Philip Werner; Kränkel, Christian; Huber, Günter; Tonelli, Mauro

    2014-12-01

    We present laser results obtained from a Dy³?-Tb³? co-doped LiLuF? crystal, pumped by a blue emitting InGaN laser diode, aiming for generation of a compact 578 nm source. We exploit the yellow Dy³? transition ?F(9/2)??H(13/2) to generate yellow laser emission. The lifetime of the lower laser level is quenched, via energy transfer, to co-doped Tb³? ions in the fluoride crystal. We report the growth technique, spectroscopic study, and room temperature continuous wave laser results in a hemispherical cavity at 574 nm, and with a highly reflective output coupler at 578 nm. A yellow laser at 578 nm is very relevant for metrological applications, in particular for pumping of the forbidden ¹S?-³P? ytterbium clock transition, which is recommended as a secondary representation of the second in the international system of units. PMID:25490638

  3. Identification of Shape Coexistence in the N=90 Isotones: Gd-154 and Dy-156

    NASA Astrophysics Data System (ADS)

    Kulp, W. D.; Wood, J. L.; Krane, K. S.; Loats, Jeff; Schmelzenbach, Paul; Stapels, C. J.; Norman, E. B.; Larimer, Ruth-Mary

    2000-10-01

    We have studied the excited states of ^154Gd and ^156Dy following the radioactive decays of ^154Eu, ^154g,m1,m2Tb and ^156Ho using the 8? spectrometer at the LBNL 88-inch cyclotron. Based on gamma-ray coincidence data, we have established band structure built on 0^+ states in ^154Gd and ^156Dy at 1182 and 1148 keV, respectively. These structures are either quasi-rotational or vibrational. There appears to be an analogous structure in ^152Sm built on a 0^+ state at 1083 keV. These results indicate that ^152Sm may possess an even more complex collective structure than that suggested recently^1. ^1 Phys. Rev. C 60,054312 Work supported in part by the US DOE under contracts: DE-FG02-96ER40958 (Georgia Institute of Technology), DE-FG03-98ER41060 (Oregon State University), and DE-AC03-76SF00098 (Lawrence Berkeley National Laboratory)

  4. Exchange coupling in TbCu and DyCu single-molecule magnets and related lanthanide and vanadium analogs.

    PubMed

    Ishida, Takayuki; Watanabe, Ryo; Fujiwara, Kei; Okazawa, Atsushi; Kojima, Norimichi; Tanaka, Go; Yoshii, Shunsuke; Nojiri, Hiroyuki

    2012-11-28

    Heterometallic coordination compounds [Cu(II)(L)(C(3)H(6)O)Ln(III)(NO(3))(3)] and [V(IV)O(L)(C(3)H(6)O)Ln(III)(NO(3))(3)] (abbreviated as LnCu and LnV, respectively; H(2)L = N,N'-bis(3-methoxysalicylidene)-1,3-diamino-2,2-dimethylpropane; Ln = Gd, Tb, Dy, Ho, and Er) were synthesized, and the X-ray crystallographic analysis shows that their structures are isomorphous for each series. The single-molecule magnet behavior was observed for TbCu and DyCu, and the activation energies of magnetization reversal were 42.3(4) and 11.5(10) K, respectively. The magnetic exchange couplings in LnCu and LnV were precisely evaluated by means of combined high-frequency EPR and pulsed-field magnetization studies, to give J(Tb-Cu)/k(B)? 3.3 K, J(Dy-Cu)/k(B) = 1.63(1) K, J(Ho-Cu)/k(B) = 1.09(2) K, and J(Er-Cu)/k(B) = 0.24(1) K. A monotonic decrease of ferromagnetic J(Ln-Cu) was found in the order of the atomic number, (64)Gd to (68)Er. The corresponding exchange parameters in LnV are smaller than those of the Cu derivatives, and J(Gd-V) was antiferromagnetic (-3.0 K determined from the magnetization jump). A possible mechanism for the exchange coupling and chemical trend is discussed. PMID:22918417

  5. Luminescent properties of BaAl12O19:Tb, Dy phosphors prepared by sol-gel method.

    PubMed

    Xiao, Lin J; Xie, Ying; He, Ming R; Chen, Yong J; Geng, Xiu J; Li, Wen Z

    2014-06-01

    BaAl12O19:Tb, Dy phosphor was prepared by the sol-gel technique using citric acid as a complextant. XRD was used to characterize the relevant crystallization behavior of the phosphor. The luminescence properties and energy transfer between Tb3+ and Dy3+ were investigated. The results revealed that energy transfer exists between Dy3+ and Tb3+ at appropriate Tb3+ concentrations. The emission intensity of Tb3+ increases and energy transfer happens from Dy3+ to Tb3+ ions at the higher content of Tb3+ when Tb3+ and Dy3+ ions were co-doped. BaAl12O19 phosphors doped with Tb3+ or Dy3+ ions only were studied to compared with BaAl12O19:Tb, Dy phosphors. The results showed that the maximum excitation peak of BaAl12O19:Tb is 240 nm and the emission spectrum consists of four peaks at 490, 545, 590, and 625 nm, originating from 5D4 --> 7FJ (J = 6, 5, 4, 3) transitions of Tb3+ ion, respectively. The excitation peaks of BaAl12O19:Dy are at 291, 324 nm and the emissions of Dy3+ are at 370, 447 and 578 nm, originating from 4F9/2 --> 6P5/2, 4F9/2 --> 6H15/2 and 4F9/2 --> 6H13/2 transitions of Dy3+ ion, respectively. PMID:24738430

  6. Angle-Resolved Photoemission Study of the Evolution of Band Structure And Charge Density Wave Properties in Rte (3) (R=Y, La, Ce, Sm, Gd, Tb, And Dy)

    SciTech Connect

    Brouet, V.; Yang, W.L.; Zhou, X.J.; Hussain, Z.; Moore, R.G.; He, R.; Lu, D.H.; Shen, Z.X.; Laverock, J.; Dugdale, S.B.; Ru, N.; Fisher, I.R.

    2009-05-12

    We present a detailed angle-resolved photoemission spectroscopy (ARPES) investigation of the RTe{sub 3} family, which sets this system as an ideal 'textbook' example for the formation of a nesting driven charge density wave (CDW). This family indeed exhibits the full range of phenomena that can be associated to CDW instabilities, from the opening of large gaps on the best nested parts of Fermi surface (up to 0.4 eV), to the existence of residual metallic pockets. ARPES is the best suited technique to characterize these features, thanks to its unique ability to resolve the electronic structure in k space. An additional advantage of RTe{sub 3} is that the band structure can be very accurately described by a simple two dimensional tight-binding (TB) model, which allows one to understand and easily reproduce many characteristics of the CDW. In this paper, we first establish the main features of the electronic structure by comparing our ARPES measurements with the linear muffin-tin orbital band calculations. We use this to define the validity and limits of the TB model. We then present a complete description of the CDW properties and of their strong evolution as a function of R. Using simple models, we are able to reproduce perfectly the evolution of gaps in k space, the evolution of the CDW wave vector with R, and the shape of the residual metallic pockets. Finally, we give an estimation of the CDW interaction parameters and find that the change in the electronic density of states n(E{sub F}), due to lattice expansion when different R ions are inserted, has the correct order of magnitude to explain the evolution of the CDW properties.

  7. Ultrasonic-assisted synthesis of core-shell structure CePO4:Tb/GdPO4 and GdPO4/CePO4:Tb nanophosphors and their photoluminescence properties

    NASA Astrophysics Data System (ADS)

    Fan, Yao-yao; Hu, Zong-chao; Yang, Jian; Zhang, Chao; Zhu, Ling

    2013-02-01

    CePO4:Tb, CePO4:Tb/GdPO4, GdPO4/CePO4:Tb and (Ce, Tb, Gd)PO4 (4-8) nm × (35-73) nm sized nanobars with the hexagonal crystal system have been obtained by ultrasonic-assisted synthesis and characterized by X-ray diffraction (XRD), FT-IR spectrum, transmission electron microscopy (TEM), photoluminescence (PL). The shell thickness of CePO4:Tb/GdPO4 and GdPO4/CePO4:Tb core/shell structure is 1.04 nm and 1.10 nm respectively. Under ultraviolet excitation, these nanophosphors show Tb3+ characteristic emission, 5D4-7FJ (J = {6, 5, 4, 3}) and the fluorescence of CePO4:Tb/GdPO4 and GdPO4/CePO4:Tb increases superficially compared with CePO4:Tb and the co-precipitated (Ce, Tb, Gd)PO4. The photoluminescence intensity of CePO4:Tb/GdPO4 is 33 times, 7 times, 2 times as high as that of CePO4:Tb, GdPO4/CePO4:Tb and (Ce, Tb, Gd)PO4, respectively. It is worth mentioning that the increasing amount of intensity of CePO4:Tb/GdPO4 is double than that of GdPO4/CePO4:Tb. A possible formation mechanism for the fluorescent efficiency enhancement has been proposed. The results are helpful in developing effective phosphors and have potential applications in field emission display (FED) and plasma display panels (PDP).

  8. Measurements of $^{152}$Gd(p,$?$)$^{153}$Tb and $^{152}$Gd(p,n)$^{152}$Tb reaction cross sections for the astrophysical $?$ process

    E-print Network

    R. T. Güray; N. Özkan; C. Yalç?n; T. Rauscher; Gy. Gyürky; J. Farkas; Zs. Fülöp; Z. Halász; E. Somorjai

    2015-06-30

    The total cross sections for the $^{152}$Gd(p,$\\gamma$)$^{153}$Tb and $^{152}$Gd(p,n)$^{152}$Tb reactions have been measured by the activation method at effective center-of-mass energies \\mbox{$3.47 \\leq E_\\mathrm{c.m.}^\\mathrm{eff}\\leq 7.94$ MeV} and \\mbox{$4.96 \\leq E_\\mathrm{c.m.}^\\mathrm{eff} \\leq 7.94$ MeV}, respectively. The targets were prepared by evaporation of 30.6\\% isotopically enriched $^{152}$Gd oxide on aluminum backing foils, and bombarded with proton beams provided by a cyclotron accelerator. The cross sections were deduced from the observed $\\gamma$-ray activity, which was detected off-line by a HPGe detector in a low background environment. The results are presented and compared with predictions of statistical model calculations. This comparison supports a modified optical proton+$^{152}$Gd potential suggested earlier.

  9. Measurements of 152Gd(p ,? )153Tb and 152Gd(p ,n )152Tb reaction cross sections for the astrophysical ? process

    NASA Astrophysics Data System (ADS)

    Güray, R. T.; Özkan, N.; Yalç?n, C.; Rauscher, T.; Gyürky, Gy.; Farkas, J.; Fülöp, Zs.; Halász, Z.; Somorjai, E.

    2015-05-01

    The total cross sections for the 152Gd(p ,? )153Tb and 152Gd(p ,n) 152Tb reactions have been measured by the activation method at effective center-of-mass energies 3.47 ?Ec.m .eff?7.94 MeV and 4.96 ?Ec.m .eff?7.94 MeV, respectively. The targets were prepared by evaporation of 30.6% isotopically enriched 152Gd oxide on aluminum backing foils, and bombarded with proton beams provided by a cyclotron accelerator. The cross sections were deduced from the observed ? -ray activity, which was detected off-line by an HPGe detector in a low background environment. The results are presented and compared with predictions of statistical model calculations. This comparison supports a modified optical proton+152Gd potential suggested earlier.

  10. Complexation of trivalent rare earth elements (Ce, Eu, Gd, Tb, Yb) by carbonate ions

    Microsoft Academic Search

    Jong Hyeon Lee; R. H. Byrne

    1993-01-01

    Carbonate stability constants for five rare earth elements (Ce[sup 3+], Eu[sup 3+], Gd[sup 3+], Tb[sup 3+], and Yb[sup 3+]) have been determined at t = 25[degrees]C and 0.70 [plus minus] 0.02 M ionic strength through solvent exchange techniques. Estimated stability constants for Ce, Eu, and Yb are in close agreement with previous work. Analyses using Gd and Tb provide the

  11. Spectroscopy and energy transfer in lead borate glasses doubly doped with Dy(3)(+)-Tb(3+) and Tb(3)(+)-Eu(3+) ions.

    PubMed

    Pisarska, Joanna; Kos, Agnieszka; Pisarski, Wojciech A

    2014-08-14

    Lead borate glasses doubly doped with Dy(3)(+)-Tb(3+) and Tb(3+)-Eu(3+) were investigated using optical spectroscopy. Luminescence spectra of rare earths were detected under various excitation wavelengths. The main green emission band due to (5)D4?(7)F5 transition of Tb(3+) is observed under excitation of Dy(3+), whereas the main red emission band related to (5)D0?(7)F2 transition of Eu(3+) is successfully observed under direct excitation of Tb(3+). In both cases, the energy transfer processes from Dy(3+) to Tb(3+) and from Tb(3+) to Eu(3+) in lead borate glasses occur through a nonradiative processes with efficiencies up to 16% and 18%, respectively. The presence of energy transfer process was also confirmed by excitation spectra measurements. PMID:24824577

  12. Magneto-optical properties of (Pr,Nd)-(Tb,Dy)-FeCo amorphous films

    SciTech Connect

    Nakada, M.; Yokota, H.; Yumoto, S.; Okada, O.; Gokan, H. (Microelectronics Research Labs., NEC Corp., Miyazaki, Miyamae-ku, Kawasaki 213 (JP))

    1989-09-01

    The authors discuss a systematic study of magneto-optical properties for four different varieties of the (Pr,Nd)-(Tb,Dy)-FeCo system focusing on temperature and wavelength dependence of Kerr rotation {theta}/sub {kappa}/ for alloy films and multilayered films. The relation between Curie temperature Tc and kerr rotation {theta}/sub {kappa}/ at 830nm wavelength was obtained for films, where Co ratio to FeCo was less than 20at%. It was found that in the range of 500 nm to 900 nm the absolute magnitude of {theta}/sub {kappa}/ for all quaternary systems was always less than that for Dy-FeCo. These results suggest that amorphous rare earth-FeCo alloy films, containing Nd or Pr, are not superior to (Tb,Dy)-FeCo films in regard to recording sensitivity and recording density in magneto-optical disks.

  13. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA Optical properties of Gd, Dy, and Tbt

    E-print Network

    Erskine, James L.

    rare-earth metals Gd, Th, and Dy. The samples are thin films prepared by vacuum evaporation (5d'6s2 ) and as metals they exhibit very similar chemical and physical behavior. Although the rare-earth rare-earth metals have been previously studied, although not extensively. The agreement between

  14. Co-existence of ac and bc-cycloidal phases, giant magnetocapacitance and polarization in the multiferroic R0.5Dy0.5MnO3 (R = Eu and Gd)

    NASA Astrophysics Data System (ADS)

    Athinarayanan, Sundaresan; de, Chandan

    2015-03-01

    In the cycloidal RMnO3 (R = Tb and Dy) multiferroic compounds, the cycloidal spin propagates along the bc plane and polarization appears along c-direction. In the case of GdMnO3, it appears that the cycloidal plane is along the ab plane and the polarization points in the a-direction. In my talk, I will demonstrate the emergence of these two cycloidal ordered phases with temperature and their co-existence from the measurements of pyroelectric current and dielectric properties in mixed rare-earth compounds, Eu0.5Dy0.5MnO3 and Gd0.5Dy0.5MnO3. The obtained value of polarization is in the same order of magnitude as in the E-type magnetic multiferroic (HoMnO3). Further, these compound show giant magnetic field enhancement of ferroelectric polarization (up to +150% in Gd0.5Dy0.5MnO3) in contrast to TbMnO3 (up to -10%). Also, the value of magneto-capacitance is nearly twenty times higher than that of TbMnO3. We attribute this high value of polarization and magneto-capacitance to the coexistence of ab and bc cycloidal phases. The isothermal current observed upon change of magnetic field with time, demonstrates giant magnetoelectric coupling for a number of cycle without any training effect.

  15. A new series of lanthanoid containing Keggin-type germanotungstates with acetate chelators: [{l_brace}Ln(CH{sub 3}COO)GeW{sub 11}O{sub 39}(H{sub 2}O){r_brace}{sub 2}]{sup 12-} {l_brace}Ln=Eu{sup III}, Gd{sup III}, Tb{sup III}, Dy{sup III}, Ho{sup III}, Er{sup III}, Tm{sup III}, and Yb{sup III{r_brace}}

    SciTech Connect

    Hussain, Firasat; Sandriesser, Stefan [Institute of Inorganic Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich (Switzerland); Speldrich, Manfred [Institute of Inorganic Chemistry, RWTH Aachen University, D-52074 Aachen (Germany); Patzke, Greta R., E-mail: greta.patzke@aci.uzh.c [Institute of Inorganic Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich (Switzerland)

    2011-01-15

    A series of head-on complexes of lanthanoid containing germanotungstates was isolated from a one pot reaction in an acetate buffer at pH 4.5. This convenient approach brought forward the [{l_brace}Ln(CH{sub 3}COO)GeW{sub 11}O{sub 39}(H{sub 2}O){r_brace}{sub 2}]{sup 12-} (Ln=Eu{sup III}, Gd{sup III}, Tb{sup III}, Dy{sup III}, Ho{sup III}, Er{sup III}, Tm{sup III}, and Yb{sup III}) family with acetate chelators in the rarely observed {mu}{sub 2}: {eta}{sup 2}-{eta}{sup 1} mode. All compounds were structurally characterized using various solid state analytics, such as single crystal X-ray diffraction, FT-IR spectroscopy, and thermogravimetric analysis. The isostructural polyanions crystallize in the monoclinic system (S.G. P2{sub 1}/c). Temperature-dependent magnetic susceptibility measurements were performed on the Gd{sup III}-complex which exhibits near perfect Curie-type behavior. -- Graphical abstract: A new series of acetate-chelated lanthanoid containing germanotungstates [{l_brace}Ln(CH{sub 3}COO)GeW{sub 11}O{sub 39}(H{sub 2}O){r_brace}{sub 2}]{sup 12-} (Ln=Eu to Yb) is available from a convenient one-pot reaction. The influence of the lanthanide contraction on the structural properties is discussed and the magnetic properties of the Gd-representative are investigated in detail. Display Omitted Research Highlights: {yields}Lanthanoid containing germanotungstates with acetate chelators in {mu}{sub 2} : {eta}{sup 2}-{eta}{sup 1} mode. {yields}Lanthanoid contraction in [{l_brace}Ln(CH{sub 3}COO)GeW{sub 11}O{sub 39}(H{sub 2}O){r_brace}{sub 2}]{sup 12-} (Ln=Eu{sup III}-Yb{sup III}). {yields}Facile one-pot synthesis of the lanthanoid containing germanotungstate series.

  16. Optical properties of Sm 3+ and Dy 3+ ions in Gd 2MoB 2O 9 host lattice

    NASA Astrophysics Data System (ADS)

    Meng, Fan-Gui; Zhang, Xin-Min; Seo, Hyo Jin

    2012-02-01

    Gd 2MoB 2O 9 doped with Sm 3+ and Dy 3+ were used for this study. The photoluminescence behaviors of Sm 3+ and Dy 3+ in this phosphor material were investigated by the excitation and emission spectra. The Sm 3+-doped Gd 2MoB 2O 9 phosphor powders show a red luminescence, whereas the Dy 3+-doped Gd 2MoB 2O 9 phosphor powders show a yellow luminescence. In addition, the optimum doping concentration and the time-resolved luminescence spectroscopy were also investigated.

  17. Magnetostrictive properties of rapidly quenched Tb-Dy-Fe-B alloys

    SciTech Connect

    Lim, S.H.; Kang, S.Y.; Kim, S.R. [Korea Inst. of Science and Technology, Seoul (Korea, Republic of). Magnetic Materials Lab.] [Korea Inst. of Science and Technology, Seoul (Korea, Republic of). Magnetic Materials Lab.

    1997-09-01

    The magnetostriction of melt-spun ribbons of the alloys (R{sub 0.33}Fe{sub 0.67}){sub 1{minus}x}B{sub x} (R = Tb{sub 0.3}Dy{sub 0.7} and 0 {le} x {le} 0.06) is investigated as a function of wheel speed during melt-quenching. The low field sensitivity of magnetostriction with magnetic field is found to be good for the alloys with x {le} 0.04 over a wide range of wheel speed. This magnetostrictive behavior is in contrast with that observed previously for Dy-Fe and Tb-Fe based alloys and is thought to be due to low intrinsic magnetocrystalline anisotropy of the compound.

  18. Synthesis and Luminescence Properties of Transparent Nanocrystalline GdF3:Tb Glass-Ceramic Scintillator

    PubMed Central

    Lee, Gyuhyon; Savage, Nicholas; Wagner, Brent; Zhang, Yuelan; Jacobs, Benjamin; Menkara, Hisham; Summers, Christopher; Kang, Zhitao

    2014-01-01

    Transparent glass-ceramic containing rare-earth doped halide nanocrystals exhibits enhanced luminescence performance. In this study, a glass-ceramic with Tb doped gadolinium fluoride nanocrystals embedded in an aluminosilicate glass matrix is investigated for X-ray imaging applications. The nanocrystalline glass-ceramic scintillator was prepared by a melt-quench method followed by an anneal. The GdF3:Tb nanocrystals precipitated within the oxide glass matrix during the processing and their luminescence and scintillation properties were investigated. In this nanocomposite scintillator system, the incorporation of high atomic number Gd compound into the glass matrix increases the X-ray stopping power of the glass scintillator, and effective energy transfer between Gd3+ and Tb3+ ions in the nanocrystals enhances the scintillation efficiency. PMID:24610960

  19. Synthesis and Luminescence Properties of Transparent Nanocrystalline GdF3:Tb Glass-Ceramic Scintillator.

    PubMed

    Lee, Gyuhyon; Savage, Nicholas; Wagner, Brent; Zhang, Yuelan; Jacobs, Benjamin; Menkara, Hisham; Summers, Christopher; Kang, Zhitao

    2014-03-01

    Transparent glass-ceramic containing rare-earth doped halide nanocrystals exhibits enhanced luminescence performance. In this study, a glass-ceramic with Tb doped gadolinium fluoride nanocrystals embedded in an aluminosilicate glass matrix is investigated for X-ray imaging applications. The nanocrystalline glass-ceramic scintillator was prepared by a melt-quench method followed by an anneal. The GdF3:Tb nanocrystals precipitated within the oxide glass matrix during the processing and their luminescence and scintillation properties were investigated. In this nanocomposite scintillator system, the incorporation of high atomic number Gd compound into the glass matrix increases the X-ray stopping power of the glass scintillator, and effective energy transfer between Gd(3+) and Tb(3+) ions in the nanocrystals enhances the scintillation efficiency. PMID:24610960

  20. Yellow laser performance of Dy$^{3+}$ in co-doped Dy,Tb:LiLuF$_4$

    E-print Network

    Bolognesi, Giacomo; Calonico, Davide; Costanzo, Giovanni Antonio; Levi, Filippo; Metz, Philip Werner; Kränkel, Christian; Huber, Günter; Tonelli, Mauro

    2015-01-01

    We present laser results obtained from a Dy$^{3+}$-Tb$^{3+}$ co-doped LiLuF$_{4}$ crystal, pumped by a blue emitting InGaN laser diode, aiming for the generation of a compact 578 nm source. We exploit the yellow Dy$^{3+}$ transition $^{4}$F$_{9/2}$ $\\Longrightarrow$ $^{6}$H$_{13/2}$ to generate yellow laser emission. The lifetime of the lower laser level is quenched via energy transfer to co-doped Tb$^{3+}$ ions in the fluoride crystal. We report the growth technique, spectroscopic study and room temperature continuous wave (cw) laser results in a hemispherical cavity at 574 nm and with a highly reflective output coupler at 578 nm. A yellow laser at 578 nm is very relevant for metrological applications, in particular for pumping of the forbidden $^{1}$S$_{0} \\Longrightarrow ^{3}$P$_{0}$ Ytterbium clock transition, which is recommended as a secondary representation of the second in the international system (SI) of units. This paper was published in Optics Letters and is made available as an electronic reprint ...

  1. Nuclear level structures in 160,162Tb studied with Dy161,163(t,?) reactions

    NASA Astrophysics Data System (ADS)

    Burke, D. G.; Garrett, P. E.; Sood, P. C.

    2007-10-01

    Dy161,163(t,?) angular distributions were measured using 17 MeV tritons from the McMaster University FN tandem Van de Graaff accelerator. Reaction products were analyzed with an Enge split-pole magnetic spectrograph. New nuclear structure information is reported for each of the residual odd-odd nuclides 160Tb and 162Tb. Clear assignments can be made for the K=1 and K=4 bands formed by coupling the 3[411] proton with the 5[642] neutron of the 161Dy target and with the 5[523] neutron of the 163Dy target. Bands formed by transfer of the 5[413] proton can also be assigned. Two new Gallagher-Moszkowski splitting energies are reported. Although large peaks can be attributed to transfer of the 5[532] and 7[523] protons, strong Coriolis mixings of the four two-quasiparticle bands formed by these transfers in each nuclide, coupled with the unknown Gallagher-Moszkowski splittings and Newby shifts, limit the interpretation to some tentative assignments. From reaction Q-values the mass of 162Tb is determined to be ˜80 keV higher than reported in the 2003 mass tables.

  2. Synthesis, structural characterization and photophysical properties of highly photoluminescent crystals of Eu(III), Tb(III) and Dy(III) with 2,5-thiophenedicarboxylate

    NASA Astrophysics Data System (ADS)

    Marques, Lippy F.; Cantaruti Júnior, Anderson A. B.; Ribeiro, Sidney J. L.; Scaldini, Felipe M.; Machado, Flávia C.

    2013-10-01

    Lanthanide compounds of general formula [Ln2(2,5-tdc)3(dmf)2(H2O)2]·2dmf·H2O (Ln = Eu(III) (1), Tb(III) (2), Gd(III) (3) and Dy(III) (4), dmf = N,N'-dimethylformamide and 2,5-tdc2- = 2,5-thiophedicarboxylate anion) were synthesized and characterized by elemental analysis, X-ray powder diffraction patterns, thermogravimetric analysis and infrared spectroscopy. Phosphorescence data of Gd(III) complex showed that the triplet states (T1) of 2,5-tdc2- ligand have higher energy than the main emitting states of Eu(III), Tb(III) and Dy(III), indicating that 2,5-tdc2- ligand can act as intramolecular energy donor for these metal ions. An energy level diagram was used to establish the most relevant channels involved in the ligand-to-metal energy transfer. The high value of experimental intensity parameter ?2 for the Eu(III) complex indicate that the europium ion is in a highly polarizable chemical environment. The emission quantum efficiency (?) of the 5D0 emitting level of Eu(III) was also determined. The complexes act as possible light conversion molecular devices (LCMDs).

  3. Stark splitting and energy transfer between Dy 3+ Ho 3+ and between Tb 3+ Er 3+ in calcium-lithium borate glass

    Microsoft Academic Search

    Brajesh Sharma; V B Singh; D K Rai; S B Rai

    1998-01-01

    Fluorescence spectrum of Dy3+, Dy3+-Ho3+, Tb3+ and Tb3+-Er3+ doped in calibo glass have been studied using Ar+ and excimer lasers. Non-radiative energy transfer from trivalent dysprosium and terbium (donors) to holmium and erbium (acceptors)\\u000a respectively has been observed on the basis of decrease in the life time of the levels and reduction in fluorescence intensity\\u000a of Dy3+ and Tb3+ on

  4. EPR study of some rare-earth ions (Dy3+, Tb3+, and Nd3+) in YBa2Cu3O6-compound

    Microsoft Academic Search

    M. R. Gafurov; V. A. Ivanshin; I. N. Kurkin; M. P. Rodionova; H. Keller; M. Gutmann; U. Staub

    2003-01-01

    We investigate the low temperature X-band electron paramagnetic resonance (EPR) of YBa2Cu3Ox compounds with \\/x?6.0 doped with Dy3+, Tb3+, and Nd3. The EPR spectra of Dy3+ and Tb3+ have been identified. The EPR of Tb3+ is used also to study the effect of suppression of high Tc superconductivity by doping with Tb3+. The EPR of Nd3+ is probably masked by

  5. Metamagnetic behaviors in RRu2Al10(R = Tb, Dy, Ho) single crystals

    NASA Astrophysics Data System (ADS)

    Mizushima, Toshio; Watanabe, Yuuya; Ejiri, Jun-ichi; Kuwai, Tomohiko; Isikawa, Yosikazu

    2015-03-01

    We measured the magnetization M and the specific heat C of TbRu2Al10, DyRu2Al10 and HoRu2Al10 single crystals. We observed antiferromagnetic transitions at the temperature T = 15 K for TbRu2Al10, 6.5 and 5.1 K for DyRu2Al10 and 5.0 K for HoRu2Al10 in the temperature dependences of M divided by the applied magnetic field, M/H. The magnetization curves exhibit metamagnetic behaviors below their magnetic transitions of all materials. M of TbRu2Al10 at T = 2 K along the c-axis shows the metamagnetic behavior at H = 1.2, 1.6 and 3.2 T and shows a complex behavior with small jumps around H = 4, 5 and 6.2 T along the a-axis. As for DyRu2Al10, the metamgnetic behaviors were observed at H = 0.16, 1.35 and 1.8 T along the c-axis. In addition to the magnetic transitions at T = 5.1 and 6.5 K, we observed an unusual drop around 2 K in the temperature dependence of M/H and correspondingly a kink in the magnetic specific heat at T = 1.5 K. As for the specific heat of HoRu2Al10, an upturn due to a nuclear contribution in the specific heat was observed below 1.5 K.

  6. Structural and magnetic properties of rare earth—iron–cobalt–vanadium intermetallic compounds (R: Tb, Dy)

    Microsoft Academic Search

    D Hadjiapostolidou; M Gjoka; C Sarafidis; E Pavlidou; T Bakas; O Kalogirou

    2004-01-01

    Starting with the Nd3(Fe,Ti)29 stoichiometry [Tb3(Fe1?xCox)27.4V1.6 and Dy3(Fe1?xCox)27.8V1.2; x=0.6, 0.8, 1.0] two novel series of R–Fe–Co–V intermetallic compounds with a disordered variant of the hexagonal Th2Ni17-type structure were formed. The cell parameters decrease and the Curie temperature increases with increasing Co content. XRD patterns of magnetically aligned powder samples revealed the presence of a planar magnetic anisotropy.

  7. Lanthanide oxide clusters: from tetrahedral [Dy4(?4-O)](10+) to supertetrahedral [Ln20(?4-O)11]38+ (Ln = Tb, Dy, Ho, Er).

    PubMed

    Lin, Wei-Quan; Liao, Xiao-Fen; Jia, Jian-Hua; Leng, Ji-Dong; Liu, Jun-Liang; Guo, Fu-Sheng; Tong, Ming-Liang

    2013-09-01

    Supertetrahedral clusters: A family of lanthanide oxide supertetrahedral T3{Ln20} clusters (Ln = Tb, Dy, Ho, Er; see figure) were obtained from the solvothermal reaction of lanthanide(III) salts with polytriazolate ligands that could be methylated and oxidized in situ. PMID:23794500

  8. Epitaxial growth of (110) DyFe 2, TbFe 2 and Dy 0.7Tb 0.3Fe 2 thin films by molecular beam epitaxy

    Microsoft Academic Search

    V. Oderno; C. Dufour; K. Dumesnil; Ph. Mangin; G. Marchal

    1996-01-01

    We present the first epitaxial growth of some (110) rare earth-Fe2 (DyFe2, TbFe2 and Dy0.7Tb0.3Fe2 known as terfenol-D) thin films on (110) Nb(11?20) sappire by molecular beam epitaxy. The epitaxy is initiated by the deposition of a thin layer of iron on niobium. The structures are investigated by RHEED and X-ray scattering. Depending on the thermal treatment of the iron

  9. Effect of hydrogenation on the magnetic and magnetoelastic properties of the Tb 0.27 Dy 0.73 Fe 2 and Tb 0.27 Dy 0.73 Co 2 compounds with compensated magnetic anisotropy

    Microsoft Academic Search

    G. A. Politova; I. S. Tereshina; S. A. Nikitin; T. G. Sochenkova; V. N. Verbetsky; A. A. Salamova; M. V. Makarova

    2005-01-01

    The effect of hydrogenation on the magnetic ordering temperature and magnetostriction of the Tb0.27Dy0.73Fe2 and Tb0.27Dy0.73Co2 compounds with compensated magnetic anisotropy of the rare-earth sublattice was studied. It was established that the incorporation\\u000a of hydrogen atoms into the crystal lattice of the compounds studied lowers the Curie temperature. It is shown that, in this\\u000a case (i.e., for structures of the

  10. A comparative study of the optical properties of TbRhGe and DyRhGe

    NASA Astrophysics Data System (ADS)

    Knyazev, Yu. V.; Lukoyanov, A. V.; Kuz'min, Yu. I.; Gupta, Sachin; Suresh, K. G.

    2015-06-01

    In this paper, experimental and theoretical optical properties of TbRhGe and DyRhGe have been reported and compared. Our measurements by the ellipsometric method in the wavelength range 0.22-15 ?m revealed significant differences in energy positions of the interband peaks in the spectral functions of these ternary compounds. The electronic structure of TbRhGe and DyRhGe calculated within the LSDA + U method was used to obtain theoretical optical conductivity, which is in good agreement with the experimental one. Further analysis allowed us to track changes in interband transitions related to the rare-earth 4f and rhodium 4d states, which are responsible for the observed differences in optical properties of TbRhGe and DyRhGe compounds.

  11. Structural and magnetic characterization of the ternary phase R 3(Fe,Mo) 29(R = Tb and Dy)

    Microsoft Academic Search

    Hongge Pan; Fuming Yang; Changpin Chen; Ning Tang; Xiufeng Han; Qidong Wang

    1996-01-01

    The optimum compositions and annealing conditions of the preparing single-phase R3(Fe,Mo)29 (R = Tb and Dy) are reported. The structural characterization by X-ray powder diffraction provides evidence for a Nd3(Fe,Ti)29-type compound with the space group A2\\/m. The Curie temperatures TC are 437 K for Tb3(Fe,Mo)29 and 408 K for Dy3(Fe,Mo)29. The saturation magnetization Ms values are 77.5 A m2\\/kg at

  12. Structural and magnetic characterization of the ternary phase R3(Fe,Mo)29 (R = Tb and Dy)

    Microsoft Academic Search

    H. Pan; F. Yang; N. Tang; X. Han; C. Chen; Q. Wang

    1996-01-01

    The optimum compositions and annealing conditions of the preparing single-phase R3(Fe,Mo)29 (R = Tb and Dy) are reported. The structural characterization by X-ray powder diffraction provides evidence for a Nd3(Fe,Ti)29-type compound with the space group A2\\/m. The Curie temperatures TC are 437 K for Tb3(Fe,Mo)29 and 408 K for Dy3(Fe,Mo)29. The saturation magnetization Ms values are 77.5 A m2\\/kg at

  13. Induced assembly and photoluminescence of lanthanum (Tb, Eu, Dy) complexes/ZnO/polyethylene glycol hybrid phosphors

    NASA Astrophysics Data System (ADS)

    Yan, Bing; Chen, Xi; Wu, Jianhua

    2007-08-01

    Some novel kinds of hybrid phosphors were assembled with lanthanum (Tb, Eu, Dy) complexes (with four kinds of terbium complexes is 2,4-dihydroxybenzonic acid (DHBA), 1,10-phenanthroline (phen), acetylacetone (AA) and nicotinic acid (Nic), respectively) doped ZnO/PEG particles by co-precipitation approach derived from Zn(CH 3COO) 2 (Zn(AC) 2), NaOH, PEG as precursors at room temperature. The characteristic luminescence spectra for f-f transitions of Tb 3+, Eu 3+, Dy 3+ were observed. It is worthy to point out that ZnO is the excellent host for lanthanum ions by the assembly of PEG matrices.

  14. Specific Heat of the Ferromagnets Tb(OH)3, Dy(OH)3 and Ho(OH)3

    Microsoft Academic Search

    H. E. Meissner; W. P. Wolf

    1969-01-01

    Continuing a study of the magnetic rare-earth hydroxides,1 we have measured the specific heats of hydrothermally crystallized powder samples of Tb(OH)3, Dy(OH)3 and Ho(OH)3 between 0.6° and 18°K. Sharp anomalies associated with paramagnetic-ferromagnetic phase transitions were found at 3.71° Tb(OH)3; 3.48° Dy(OH)3; and 2.54°K Ho(OH)3, in good agreement with the Curie temperatures deduced from magnetic measurements.1 Analysis of the specific

  15. EPR Studies of Gd3+, Dy3+, and Ce3+ in some Van Vleck Paramagnets

    Microsoft Academic Search

    Kazushi Sugawara; C. Y. Huang

    1976-01-01

    EPR of Gd3+ in the Van Vleck paramagnets, PrPb3 and TmCd have been investigated. The temperature-dependent linewidths have been found to be in agreement with the prediction of Moriya and Obata. In a complementary study, non-S-State Dy3+ in TmP, TmAs, PrP, PrAs, PrSb, PrBi and PrS, and Ce3+ in TmS, TmAs, PrS and PrP have been examined. For all these

  16. The Co-doped Tb 0.36Dy 0.64Fe 2 magnetostrictive alloys with a wide operating temperature range

    Microsoft Academic Search

    Tianyu Ma; Chengbao Jiang; Xiang Xu; Hu Zhang; Huibin Xu

    2005-01-01

    Magnetostrictive alloys with a wide operating temperature range from ?80 to 150°C were developed by changing the Tb\\/Dy ratio of TbxDy1?xFe2 from 0.3\\/0.7 to 0.36\\/0.64 and Co partly substituting for Fe. The structure, Curie temperature, AC susceptibility, magnetization, magnetocrystalline anisotropy constant K1 and magnetostriction of Tb0.36Dy0.64(Fe1?yCoy)2 (y=0.0, 0.1, 0.2) alloys were investigated. It was found that the matrix of Tb0.36Dy0.64(Fe1?yCoy)2

  17. Ultrathin (Gd, Tb)-FeCo Films With Perpendicular Magnetic Anisotropy

    Microsoft Academic Search

    Ching-Ming Lee; Lin-Xiu Ye; Jia-Mou Lee; Wan-Ling Chen; Chao-Yuan Huang; Gung Chern; Te-Ho Wu

    2009-01-01

    Perpendicular ultrathin RE-TM films with thickness 3 nm were investigated for potential use as free layers of perpendicular magnetic tunnel junctions. The free layer thickness should be as thin as possible to reduce spin-transfer switching current density while maintaining adequate thermal stability. Using Ti or Al as under- and over-layers, we found that both 3 nm GdFeCo and TbFeCo films

  18. Photoluminescence properties of MgY4Si3O13:Gd3+, Tb3+ under vacuum ultraviolet excitation

    NASA Astrophysics Data System (ADS)

    Zhao, Wenyu; An, Shengli; Fan, Bin; Li, Songbo

    2013-07-01

    Gd3+ and Tb3+ co-doped MgY4Si3O13 green phosphors were prepared by a solid-state reaction. The photoluminescence properties in vacuum ultraviolet-visible (VUV-vis) range and decay properties were investigated in details. The f-d transition of Gd3+ ions and spin-allowed f-d transition of Tb3+ ions locate at about 134 nm and 239 nm, respectively. Two charge transfer bands of O2- ? Gd3+ and O2- ? Tb3+ overlap at about 155 nm. Some f-f transition of Tb3+ and Gd3+ ions are confirmed in VUV-vis range. Upon excitation at 172 nm, the optimal composition of MgY3.3Si3O13:0.5Gd3+, 0.2Tb3+ phosphor exhibits the characteristic transitions of Gd3+ and Tb3+ with chromaticity coordinate of (0.2849, 0.5843). The phosphor has a shorter decay time (2.13 ms) than that of Zn2SiO4:Mn2+ (4.56 ms). The results suggest that this green phosphor is a potential candidate for mercury-free luminescence lamps and plasma display panels (PDPs) application.

  19. Synthesis and luminescent properties of BaGd2O4:Dy3+, an novel scintillating phosphor

    NASA Astrophysics Data System (ADS)

    Sun, Xin-Yuan; Zhou, Yun-Zhi; Yu, Xiao-Guang; Chen, Hao-Hong; Wang, Hong; Zhang, Zhi-Jun; Yang, Xin-Xin; Zhao, Jing-Tai

    2013-01-01

    The BaGd2- x O4: xDy3+ (0 ? x ? 0.08) phosphors were synthesized at 1,300 °C in air by the solid-state reaction route. The as-synthesized phosphors were characterized by X-ray powder diffraction, photoluminescence excitation spectra, photoluminescence (PL) spectra, X-ray excited luminescence (XEL) spectra, and thermoluminescence (TL) spectra. It is found that the quenching concentration of Dy3+ ions in BaGd2O4 host is dependent on the selected excitation wavelength. The optimal PL intensity for the investigated BaGd2- x O4: xDy3+ phosphors is found to be x = 0.01, 0.02, and 0.04, upon excitation by 234, 277, and 350 nm ultraviolet light, respectively. The energy transfer among Dy3+ ions upon excitation by 350 nm is confirmed to be an electric dipole-dipole interaction mechanism based on the fitting of Huang's rule. In addition, the intensive XEL from BaGd2O4:Dy3+ phosphor is observed by the naked eyes at room temperature, and TL properties of the investigated phosphors are analyzed and discussed. All the results imply that the investigated phosphors could be a promising scintillating phosphor.

  20. Rare earth niobium oxynitrides, LnNbON 2? ? (Ln = Y, La, Pr, Nd, Gd, Dy): Synthesis, structure and properties

    Microsoft Academic Search

    Nitesh Kumar; A. Sundaresan; C. N. R. Rao

    2011-01-01

    Ammonolysis of rare earth niobates of the type LnNbO4 (Ln=Y, La, Pr, Nd, Gd, Dy) yields oxynitrides of different structures. When Ln=La, Nd and Pr, the structure is that of an orthorhombic perovskite of the general formula LnNbON2. As the size of the rare earth decreases, the oxynitride has a nitrogen-deficient defect fluorite (Ln=Pr, Nd, Gd), or pyrochlore (Ln=Y) structure.

  1. Enhanced white light emission from GdAl3(BO3)4:Dy3+,Ce3+ nanorods

    Microsoft Academic Search

    Q Y Zhang; C H Yang; Y X Pan

    2007-01-01

    GdAl3(BO3)4 nanorods doped with rare-earth ions have been obtained via a combustion synthesis. The nanorods have been characterized by x-ray diffraction, micro-Raman spectra, various microscopy techniques and fluorescence measurements. The results show that the nanorods are of straight morphology and smooth surface with an average diameter of 60 nm. The GdAl3(BO3)4:Dy3+ nanorods show intense emissions centred at 480, 575, and

  2. Magnetostrictive properties of amorphous and nanocrystalline TbDyFe films with Nb and Zr additives

    NASA Astrophysics Data System (ADS)

    Speliotis, A.; Kalogirou, O.; Vouroutzis, N.; Niarchos, D.

    1998-08-01

    Amorphous and nanocrystalline giant magnetostrictive thin films of the composition (Tb 0.3Dy 0.7) 40(Fe 0.95X 0.05) 60 (X=Nb, Zr) have been prepared by DC magnetron sputtering at substrate temperatures of TS=440 and 470°C. At TS=440°C the films are amorphous and present magnetostriction of ?350 ppm at the maximum applied field, 4 kOe, and at room temperature, which is comparable to those without Nb or Zr. In the case of the Nb samples deposited at 470°C, nanocrystalline films with room-temperature magnetostriction as large as 500 ppm at 4 kOe and with coercivity lower than 30 Oe are obtained.

  3. Magnetochromic effect in multiferroic R In1 -xMnxO3 (R =Tb , Dy)

    NASA Astrophysics Data System (ADS)

    Chen, P.; Holinsworth, B. S.; O'Neal, K. R.; Brinzari, T. V.; Mazumdar, D.; Topping, C. V.; Luo, X.; Cheong, S.-W.; Singleton, J.; McGill, S.; Musfeldt, J. L.

    2015-05-01

    We combined high field magnetization and magneto-optical spectroscopy to investigate spin-charge coupling in Mn-substituted rare-earth indium oxides of chemical formula R In1 -xMnxO3 (R =Tb , Dy). The edge states, on-site Mn3 +d to d excitations, and rare-earth f -manifold excitations all track the magnetization energy due to dominant Zeeman interactions. The field-induced modifications to the rare-earth excitations are quite large because spin-orbit coupling naturally mixes spin and charge, suggesting that the next logical step in the design strategy should be to bring spin-orbit coupling onto the trigonal bipyramidal chromophore site with a 4 or 5 d center.

  4. Magnetochromic effect in multiferroic R In 1 ? x Mn x O 3 ( R = Tb , Dy)

    DOE PAGESBeta

    Chen, P.; Holinsworth, B. S.; O'Neal, K. R.; Brinzari, T. V.; Mazumdar, D.; Topping, C. V.; Luo, X.; Cheong, S.-W.; Singleton, J.; McGill, S.; Musfeldt, J. L.

    2015-05-01

    We combined high field magnetization and magneto-optical spectroscopy to investigate spin-charge coupling in Mn-substituted rare-earth indium oxides of chemical formula RIn??xMnxO? (R=Tb, Dy). The edge states, on-site Mn³?d to d excitations, and rare-earth f-manifold excitations all track the magnetization energy due to dominant Zeeman interactions. The field-induced modifications to the rare-earth excitations are quite large because spin-orbit coupling naturally mixes spin and charge, suggesting that the next logical step in the design strategy should be to bring spin-orbit coupling onto the trigonal bipyramidal chromophore site with a 4 or 5d center.

  5. Brilliant Sm, Eu, Tb and Dy chiral lanthanide complexes withstrong circularly polarized luminescence

    SciTech Connect

    Petoud, Stephane; Muller, Gilles; Moore, Evan G.; Xu, Jide; Sokolnicki, Jurek; Riehl, James P.; Le, Uyen; Cohen, Seth M.; Raymond,Kenneth N.

    2006-07-10

    The synthesis, characterization and luminescent behavior of trivalent Sm, Eu, Dy and Tb complexes of two enantiomeric, octadentate, chiral, 2-hydroxyisophthalamide ligands are reported. These complexes are highly luminescent in solution. Functionalization of the achiral parent ligand with a chiral 1-phenylethylamine substituent on the open face of the complex in close proximity to the metal center yields complexes with strong circularly polarized luminescence (CPL) activity. This appears to be the first example of a system utilizing the same ligand architecture to sensitize four different lanthanide cations and display CPL activity. The luminescence dissymmetry factor, g{sub lum}, recorded for the Eu(III) complex is one of the highest values reported, and this is the first time the CPL effect has been demonstrated for a Sm(III) complex with a chiral ligand. The combination of high luminescence intensity with CPL activity should enable new bioanalytical applications of macromolecules in chiral environments.

  6. Luminescent properties of single Dy3+ ions activated Ca3Gd7(PO4)(SiO4)5O2 phosphor

    NASA Astrophysics Data System (ADS)

    Tong, Miaohui; Liang, Yujun; Li, Guogang; Xia, Zhanggen; Zhang, Mengfei; Yang, Fan; Wang, Qiang

    2014-07-01

    Single Dy3+ ions activated Ca3Gd7(PO4)(SiO4)5O2: Dy3+ (CGPS: Dy3+) phosphors were successfully synthesized by solid-state reaction method. The X-ray diffraction results confirm that the as-prepared CGPS: Dy3+ samples are pure CGPS hexagonal phase. Moreover, the substitution of Dy3+ for Gd3+ in CGPS host leads to the major diffraction peaks moving towards larger angle due to a smaller ions radius of Dy3+ than Gd3+. Upon excitation of 275 nm and 349 nm ultra violet (UV) that are respectively attributed to 8S ? 6I transitions of Gd3+ and 6H15/2 ? 6P7/2 transition of Dy3+, the characteristic emission of Dy3+ ions such as 4F9/2 ? 6H15/2 (480 nm) and 4F9/2 ? 6H13/2 (572 nm) can be clearly observed. A high ratio of yellow emission to blue emission (Y/B) implies that Dy3+ ions prefer to occupy low-symmetry 6h (Cs) sites in CGPS matrix. Therefore, white light can be obtained from Dy3+ mono-doped CGPS: Dy3+ phosphor with CIE chromaticity coordinates of (x = 0.328, y = 0.343). By calculation, the mechanism of concentration quenching between Dy3+ ions is electric dipole-dipole interaction. In addition, the energy transfer (ET) from Gd3+ to Dy3+ can also be observed. These results suggest that CGPS: Dy3+ phosphors could be a promising candidate for UV-based white light illumination.

  7. Host-sensitized luminescence properties in CaNb2O6:Ln(3+) (Ln(3+) = Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+)) phosphors with abundant colors.

    PubMed

    Li, Kai; Liu, Xiaoming; Zhang, Yang; Li, Xuejiao; Lian, Hongzhou; Lin, Jun

    2015-01-01

    A series of Ln(3+) (Ln(3+) = Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+)) ion doped CaNb2O6 (CNO) phosphors have been prepared via the conventional high-temperature solid-state reaction route. The X-ray diffraction (XRD) and structure refinement, diffuse reflection, photoluminescence (PL), and fluorescent decay curves were used to characterize the as-prepared samples. Under UV radiation, the CNO host present a broad emission band from about 355 to 605 nm centered around 460 nm originating from the NbO6 octahedral groups, which has spectral overlaps with the excitation of f-f transitions of Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+) in CNO:Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+) samples. They show both host emission and respective emission lines derived from the characteristic f-f transitions of activators, which present different emission colors owing to the energy transfer from the NbO6 group in the host to Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+) with increasing activator concentrations. The decreases of decay lifetimes of host emissions in CNO:Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+) demonstrate the energy transfer from the hosts to Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+). The energy transfer mechanisms in CNO:Eu(3+)/Tb(3+)/Dy(3+) phosphors have been determined to be a resonant type via dipole-dipole mechanisms. For CNO:Sm(3+), the metal-metal charge transfer transition (MMCT) might contribute to the different variations of decay lifetimes and emission intensity from CNO:Eu(3+)/Tb(3+)/Dy(3+) samples. The best quantum efficiency is 71.2% for CNO:0.01/0.02Dy(3+). The PL properties of as-prepared materials indicate the promising application in UV-pumped white-emitting lighting diodes field. PMID:25495521

  8. Phase diagrams of the Tb-Ag-In and Dy-Ag-In systems at 870 K

    SciTech Connect

    Demchyna, M., E-mail: marta.dem.85@gmail.com [Faculty of Chemistry, Ivan Franko National University of Lviv, Kyryla and Mefodiya Str. 6, UA-79005 Lviv (Ukraine); Belan, B.; Manyako, M. [Faculty of Chemistry, Ivan Franko National University of Lviv, Kyryla and Mefodiya Str. 6, UA-79005 Lviv (Ukraine); Pietraszko, A. [W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, PO Box 1410, 50-950 Wroclaw 2 (Poland); Kalychak, Ya. [Faculty of Chemistry, Ivan Franko National University of Lviv, Kyryla and Mefodiya Str. 6, UA-79005 Lviv (Ukraine)

    2012-08-15

    The phase equilibria of Tb-Ag-In and Dy-Ag-In ternary systems have been studied at 870 K in the whole concentration range by means of X-ray powder, single crystal X-ray diffraction and EDX analyses. Isothermal sections of Tb-Ag-In and Dy-Ag-In phase diagrams at this temperature have been constructed. Both systems are characterized by formation of three ternary compounds: REAg{sub 3}In{sub 3} (YbAg{sub 2}In{sub 4}-type, space group Im-3), REAg{sub 2}In (MnCu{sub 2}Al-type, space group Fm-3m) and RE{sub 2}AgIn{sub 3} (CaIn{sub 2}-type, space group P6{sub 3}/mmc) RE=Tb, Dy. Homogeneity ranges of the ternary phases with CaIn{sub 2} structure type lies from 35 to 60 at% of In for Tb-containing phase and from 39 to 50 at% of In for Dy-containing phase. The existence of solid solutions based on REAg (CsCl-type, space group Pm-3m) binary compounds up to 30 at% of In and REIn{sub 3} (AuCu{sub 3}-type, space group Pm-3 m) binary compounds up to 5 at% of Ag has been found. - Graphical Abstract: Phase relations in the ternary systems Tb-Ag-In and Dy-Ag-In have been established for the isothermal section at T=870 K based on X-ray powder and single crystal diffraction analyses. The existence of three ternary compounds in each system were observed. Highlights: Black-Right-Pointing-Pointer Isothermal section of Tb-Ag-In system at T=870 K was constructed. Black-Right-Pointing-Pointer Isothermal section of Dy-Ag-In system at T=870 K was constructed. Black-Right-Pointing-Pointer Three ternary compounds and two solid solutions in each system were detected.

  9. Magnetostriction of R 2Fe 17 (R=Tb,Dy,Ho and Er) and their nitrides and hydrides

    Microsoft Academic Search

    S. A. Nikitin; E. A. Ovtchenkov; A. A. Salamova; I. S. Tereshina; V. N. Verbetsky

    1999-01-01

    The magnetostriction of R2Fe17(N,H)x (R=Tb,Dy,Ho and Er) is measured on isotropic powder pressed samples in the temperature range 80–300 K in magnetic fields up to 1.3 T. The measured anisotropic magnetostrictions reflect the basal plane elliptical distortions, ??,2. Nitrogenation and hydrogenation both lead to a change of the signs of these distortions.

  10. Zone center phonons of the orthorhombic RMnO3 (R = Pr, Eu, Tb, Dy, Ho) perovskites

    E-print Network

    Gupta, Hem Chandra

    2008-01-01

    A short range force constant model (SRFCM) has been applied for the first time to investigate the phonons in RMnO3 (R = Pr, Eu, Tb, Dy, Ho) perovskites in their orthorhombic phase. The calculations with 17 stretching and bending force constants provide good agreement for the observed Raman frequencies. The infrared frequencies have been assigned for the first time. PACS Codes: 36.20.Ng, 33.20.Fb, 34.20.Cf

  11. Crystal structure of Tb5Ni2In4, and magnetic properties of Dy5Ni2In4

    SciTech Connect

    Provino, A.; Mudryk, Y.; Paudyal, D.; Smetana, V.; Manfrinetti, P.; Pecharsky, V.K.; Gschneidner Jr, Karl; Corbett, J.D.

    2012-02-27

    The crystal structure of the R5Ni2In4 intermetallic compounds was earlier reported for R Ho, Er, Tm, and Lu (Lu5Ni2In4-type, oP22, Pbam); more recently the isostructural phases Dy5Ni2In4 and Sc5Ni2In4 have also been identified. Three inequivalent crystallographic sites are occupied by the R atoms in these compounds. We have synthesized and characterized Dy5Ni2In4 and the two new isotypic compounds Tb5Ni2In4 and Y5Ni2In4. So far, none of the physical properties have been reported on any of these phases; in this article we report on the physical properties of the Dy5Ni2In4 and the crystal structure of Tb5Ni2In4 and Y5Ni2In4 compounds. Measurements of the magnetic properties performed on Dy5Ni2In4 show a ferromagnetic-like ordering with a T-C approximate to 105 K, followed by multiple magnetic orderings at lower temperatures. The fit of the inverse susceptibility in the paramagnetic state follows the Curie-Weiss law, where mu(eff). - 10.3 mu(B)/Dy-atom (close to theoretical value of 10.64 mu(B) for the free ion Dy3+) and a positive paramagnetic Curie temperature theta(p) - 58 K. Ni atoms are most likely to be nonmagnetic. The heat capacity also shows three peaks: a large one at 103K and two weaker at 12 and 8 K, respectively; the in-field heat capacity data corroborate these results, suggesting ferromagnetic and antiferromagnetic orderings at the temperature of 103 and 12 K, respectively. Low temperature x-ray diffraction has shown that the compound does not undergo any structural change down to 5K. (C) 2012 American Institute of Physics.

  12. EPR spectra in R2BaCuO5 (R=Y, Sm, Eu, Gd, Dy, Ho) oxides

    Microsoft Academic Search

    Yu. A. Koksharov; V. V. Moshchalkov; A. A. Gippius; B. V. Mill; Y. Zoubkova; S. V. Gudenko; A. N. Mezhuev

    1991-01-01

    We studied temperature dependencies (4÷300 K) of EPR spectra in R2BaCuO5 (R=Y, Sm, Eu, Gd, Dy, Ho) single crystals and ceramics. When R3+ is nonmagnetic the Cu2+ (S=1\\/2) EPR signal is absent at room temperatures. We computed the (3d)9 and (3d)8 configurations crystal field splitting using the ligand field theory. In Gd2BaCuO5 single crystals the anisotropy of resonance field and

  13. Magnetic properties of RE(Fe^Rh1_JC)2, RE = Y, Gd, Dy, Ho J. Hrubec and W. Steiner

    E-print Network

    Boyer, Edmond

    , from XY(Fe,Rh>2 a n ^ assuming a Curie Weiss law (6 = -- 25 K independent of x) jUrff/Fe = 3.5 (+ 0Magnetic properties of RE(Fe^Rh1_JC)2, RE = Y, Gd, Dy, Ho J. Hrubec and W. Steiner Inst. f. Angew-paramagnet. At4 K no ordering temperatures could be detected for Y(Fe, Rh)2 from bulk magnetic measurements

  14. Specific features of the formation of atomic magnetic moments in amorphous films RE-Co ( RE = La, Gd, Tb)

    NASA Astrophysics Data System (ADS)

    Vas'kovskiy, V. O.; Adanakova, O. A.; Balymov, K. G.; Kulesh, N. A.; Svalov, A. V.; Stepanova, E. A.

    2015-06-01

    A systematic investigation of the magnetic properties of amorphous films in ( RE) x Co100 - x binary systems in the ground state with rare-earth elements ( RE) of different types has been performed. The concentration dependences of the average atomic magnetic moments of cobalt ( m Co), gadolinium ( m Gd), and terbium ( m Tb) have been determined from the analysis of the spontaneous magnetization of the films with a nonmagnetic rare-earth element (La), a rare-earth element with a spherical electron shell (Gd), and a rareearth element with a large orbital magnetic moment (Tb). It has been shown that, in the range 0 < x < 50 at %, the magnetic moment m Co decreases from 1.7 ?B to zero, the magnetic moment m Gd remains unchanged and almost coincides with the magnetic moment of the free atom (7 ?B), and the value of m Tb decreases monotonically, but the rate of decrease depends on the method of the sample preparation. The revealed regularities are associated with the concentration change in the electronic structure of cobalt and with the specificity of the magnetic structure of the films, which has a ferromagnetic, ferrimagnetic, or sperimagnetic character for samples containing La, Gd, or Tb, respectively.

  15. Transport properties of RPtBi (R = Gd, Dy, Tm, and Lu) under applied magnetic fields

    NASA Astrophysics Data System (ADS)

    Mun, Eundeok; Bud'Ko, Sergey; Canfield, Paul

    2015-03-01

    It has been suggested that the combination of strong spin-orbit coupling and noncentrosymmetric crystal structure make ternary Heusler compounds a strong candidate for 3D topological materials. The crystal structure of rare-earth platinum bismuth (RPtBi) half-Heusler compounds lacks an inversion symmetry, hence the material is a noncentrosymmeteric. The earlier electrical resistivity data of RPtBi revealed a systematic change from a small gap semiconductor for lighter rare-earth to metallic for heavier rare-earth compounds. The angle resolved photoemission spectroscopy showed a clear spin-orbit splitting of the surface bands that cross the Fermi surface. Here we present very large magnetic field dependences of transport properties in single crystals of RPtBi (R = Gd, Dy, Tm, and Lu). Successfully grown the high quality RPtBi single crystals reveal that a large non-saturating magnetoresistance (MR) of as high as 800 % at 2 K and over 300 % at 300 K under a moderate magnetic field of 14 T. In addition to the large MR, the samples exhibit pronounced temperature and magnetic field dependences of Hall coefficient and thermoelectric power. Obtained transport data suggest that the high hole and electron mobility dominate the magnetotransport.

  16. Mössbauer studies and enhanced electrical properties of R (R=Sm, Gd and Dy) doped Ni ferrite

    NASA Astrophysics Data System (ADS)

    Inbanathan, S. S. R.; Vaithyanathan, V.; Arout Chelvane, J.; Markandeyulu, G.; Kamala Bharathi, K.

    2014-03-01

    Structural, Mössbauer studies and improved electrical characteristics of Sm, Gd and Dy doped Ni ferrite materials in comparison to that of pure NiFe2O4 are reported. Pure NiFe2O4 crystallizes in inverse spinel phase without any impurity phase. NiFe1.925Sm0.075O4, NiFe1.925Gd0.075O4 and NiFe1.925Dy0.075O4 compounds crystallize in the cubic inverse spinel phase with a very small amount of RFeO3 as additional phase. The back scattered electron imaging analysis indicates the primary and secondary phase formation in NiFe1.925Sm0.075O4, NiFe1.925Gd0.075O4 and NiFe1.925Dy0.075O4 compounds. The room temperature DC resistivity values of NiFe2O4, NiFe1.925Sm0.075O4, NiFe1.925Gd0.075O4 and NiFe1.925Dy0.075O4 compounds are found to be 17×107 ? cm, 162×107 ? cm, 171×107 ? cm and 305×107 ? cm respectively. The AC resistivity values (at 1 KHz) of NiFe2O4, NiFe1.925Sm0.075O4, NiFe1.925Gd0.075O4 and NiFe1.925Dy0.075O4 materials are 10×105 ? cm, 77×105 ? cm, 147×105 ? cm and 251×105 ? cm, respectively. Temperature dependent electrical resistivity curves reveal two different types of conduction mechanisms. The hyperfine parameters viz., the hyperfine magnetic field, the isomer shift and the quadrupole splitting confirms the substitutions of R3+ ions at B site and their effects on superexchange interactions and structural distortion. The enhanced electrical resistivity of rare earth doped Ni ferrite suggest that tuning properties for desired high frequency applications can be achieved by controlling the doping element and their amount.

  17. Dy-V magnetic interaction and local structure bias on the complex spin and orbital ordering in Dy1?xTbxVO3 (x=0 and 0.2)

    SciTech Connect

    Yan, J.-Q.; Cao, H. B.; McGuire, M. A.; Ren, Y.; Sales, B. C.; Mandrus, D. G.

    2013-06-01

    The spin and orbital ordering in Dy1?xTbxVO3 (x=0 and 0.2) was studied by measuring x-ray powder diffraction, magnetization, specific heat, and neutron single-crystal diffraction. The results show that G-OO/C-AF and C-OO/G-AF phases coexist in Dy0.8Tb0.20VO3 in the temperature range 2–60 K, and the volume fraction of each phase is temperature and field dependent. The ordering of Dy moments at T*?=?12 K induces a transition from G-OO/C-AF to a C-OO/G-AF phase. Magnetic fields suppress the long-range order of Dy moments and thus the C-OO/G-AF phase below T*. The polarized moments induced at the Dy sublattice by external magnetic fields couple to the V 3d moments, and this coupling favors the G-OO/C-AF state. Also discussed is the effect of the Dy-V magnetic interaction and local structure distortion on the spin and orbital ordering in Dy1?xTbxVO3.

  18. Tuning of crystal phase and luminescence properties of Gd{sub 2}(MoO{sub 4}){sub 3}:Dy{sup 3+} phosphors

    SciTech Connect

    Xia, Wanwan; Wang, Xiaojie [State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012 (China) [State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012 (China); Key Lab of Coherent Light, Atomic and Molecular Spectroscopy, Ministry of Education, Changchun 130012 (China); Fu, Zuoling, E-mail: zlfu@jlu.edu.cn [State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012 (China) [State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012 (China); Key Lab of Coherent Light, Atomic and Molecular Spectroscopy, Ministry of Education, Changchun 130012 (China); Zhou, Shihong; Zhang, Siyuan [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)] [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Jeong, Jung Hyun, E-mail: jhjeong@pknu.ac.kr [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2012-09-15

    Graphical abstract: The optical properties of Dy{sup 3+} were found to be sensitive to the crystal phase of the as-synthesized Gd{sub 2}(MoO{sub 4}){sub 3}:Dy{sup 3+} phosphors, especially the distinct features of the charge transfer (CT) transition. The mechanism involved was discussed in detail based on the experiments and theoretic calculations. Highlights: ? The crystal phase of Gd{sub 2}(MoO{sub 4}){sub 3}:Dy{sup 3+} was tuned by changing the pH value of the solution in hydrothermal system. ? The optical properties of Dy{sup 3+} were found to be sensitive to the crystal phase of Gd{sub 2}(MoO{sub 4}){sub 3}:Dy{sup 3+}. ? The mechanisms of different crystal phases affected on the luminescence properties of Gd{sub 2}(MoO{sub 4}){sub 3}:Dy{sup 3+} were discussed. -- Abstract: The orthorhombic and monoclinic Gd{sub 2}(MoO{sub 4}){sub 3}:Dy{sup 3+} were successfully synthesized by a hydrothermal process with a subsequent annealing treatment at 800 °C for 4 h. The crystal phase of Gd{sub 2}(MoO{sub 4}){sub 3}:Dy{sup 3+} was controlled as a function of the pH value of the solution. The crystallization and microstructures of the samples were characterized by Powder X-ray diffraction (XRD) and scanning electron micrograph (SEM). Furthermore, the optical properties were investigated by the diffuse reflection, excitation and emission spectra. The mechanisms of different crystal phases affected on the luminescence properties of Gd{sub 2}(MoO{sub 4}){sub 3}:Dy{sup 3+} were discussed. The electric dipole–dipole interaction between Dy{sup 3+} ions was identified as the main mechanism for the concentration quenching of the two structures. Finally, the chromatic natures of all the samples were analyzed in detail. The results indicate that the orthorhombic phosphor Gd{sub 1.84}(MoO{sub 4}){sub 3}:Dy{sub 0.16}{sup 3+} can be considered as a suitable candidate for white light emitting diodes (W-LEDs).

  19. Enhanced luminescence via energy transfer from Ag+ to RE ions (Dy3+, Sm3+, Tb3+) in glasses.

    PubMed

    Li, JingJing; Wei, RongFei; Liu, XueYun; Guo, Hai

    2012-04-23

    Oxyfluoride glasses containing Ag species and rare earth (RE) ions (Dy(3+), Sm(3+), Tb(3+)) were prepared by melt-quenching technique. The type of luminescent species of novel excitation band (230-300 nm peaked at 255 nm) and emission band (300-600 nm peaked at 350 nm) were investigated by absorption, excitation, emission spectra, as well as decay lifetime measurements and can be ascribed to isolated Ag(+) ions. Owing to energy transfer from Ag(+) to RE ions, significant enhancements of RE ions emission (76 times for Sm(3+), 41 times for Dy(3+)) were observed for non-resonant UV excitation (255 nm). Our research may extend the understanding of interactions between RE ions and Ag species. PMID:22535104

  20. TDPAD measurement of magnetic hyperfine field for 66Ga and 71As in ferromagnetic Gd and Tb

    NASA Astrophysics Data System (ADS)

    Mohanta, S. K.; Davane, S. M.; Mishra, S. N.

    2013-05-01

    We have measured the temperature dependence of magnetic hyperfine field for 66Ga and 71As in ferromagnetic rare earth hosts Gd and Tb using TDPAD method. High spin isomeric states: 7 - in 66Ga and 9/2 + in 71As, excited by the nuclear reactions 12C(56Fe, pn)66Ga and 12C(63Cu, 2p2n)71As were used as nuclear probes for magnetic hyperfine interaction studies. The saturation the hyperfine fields, Bhf(0) for 66Ga in Gd and Tb have been determined as: 11.4 kG in Gd and 3.5 kG respectively. The Bhf(0) values for 71As have been found to be 45 kG in Gd and 14.1 kG in Tb. The measured hyperfine field values for 66Ga and 71As, scaled by the 5d moments of the rare earth hosts, follow the systematic trend observed in 3d ferromagnets viz. Fe, Co and Ni.

  1. Optimization of magnetostriction, coercive field and magnetic transition temperature in nanocrystalline TbDyFe+Zr/Nb multilayers

    NASA Astrophysics Data System (ADS)

    Fischer, S. F.; Kelsch, M.; Kronmüller, H.

    1999-06-01

    The magnetostrictive properties of TbDyFe/Nb multilayers containing 2 at% Zr as an additive have been investigated after different annealing treatments for the (Terfenol-D near) composition of [Tb 0.27Dy 0.73] 0.27Fe 0.73. The multilayer structure has been produced by ion-beam sputtering on a sapphire substrate. After 10 min annealing of the multilayers at temperatures from 873 to 973 K the parallel magnetostriction increased from ??(0.8 T)=265 to 520 ppm accompanied by an increase of the magnetic phase transition temperature from TC=333 to 592 K, while the increase of the coercive fields from ?0Hc<5 to 75 mT lies distinctively below 100 mT. These properties are suitable for applications of giant magnetostrictive films in microsystems where values of ?>500 ppm, TC>500 K and ?0Hc?100 mT are required. Establishing a nanocrystalline microstructure with grain sizes d< dc˜15 nm ( dc is the critical grain diameter) smaller than the exchange length is essential for the combination of intrinsic magnetic properties (increased ? and TC) with soft magnetic properties ( ?0Hc of a few mT) as typical for an amorphous microstructure. It is shown by microstructural XRD and TEM investigations that such a nanocrystalline microstructure can be realized by a suitable heat treatment of TbDyFe+Zr/Nb multilayers. Introducing Nb spacer layers effectively reduces grain growth for certain annealing temperatures while Zr is assumed to play a dominant role in forming nucleation centers of nanograins. In combination, both effects can be well used to optimize the magnetostrictive layer properties.

  2. Magnetic and magnetoelastic properties of single crystal Tb{sub 0.5}Dy{sub 0.5}Zn

    SciTech Connect

    Restorff, J.B.; Wun-Fogle, M.; Teter, J.P.; Cullen, J.R. [Naval Surface Warfare Center, Silver Spring, MD (United States). White Oak Lab.] [Naval Surface Warfare Center, Silver Spring, MD (United States). White Oak Lab.; Clark, A.E. [Clark Associates, Adelphi, MD (United States)] [Clark Associates, Adelphi, MD (United States)

    1996-09-01

    Magnetization, magnetostriction, and modulus measurements have been performed on single crystal specimens of the pseudobinary Tb{sub 0.5}Dy{sub 0.5}Zn. Non-principal axis easy magnetization directions were observed in the (001) plane at temperatures below 20 K. At all temperatures, [110] is the hard axis. At 2.2 K the anisotropy field is estimated to be 5.6 MA/m (70 kOe). Magnetostriction and modulus measurements at 77 K showed a saturation magnetostriction of {approximately}5 {times} 10{sup {minus}3} and a modulus that varied from 10--60 MPa depending on field.

  3. Exchange coupling coefficient and domain wall mobility of (Dy,Tb)FeCo magneto-optical films

    SciTech Connect

    Hwang, W.; Wu, T.; Shieh, H.D. [Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu, Taiwan, 30010, Republic of (China)] [Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu, Taiwan, 30010, Republic of (China)

    1997-06-01

    The magnetic properties and recording characteristics of (Dy,Tb)FeCo films are dependent upon the anisotropy dispersion of rare earth constituents and the exchange integral between rare earth and transition metal sub networks. The exchange coupling coefficient {lambda} and the domain wall mobility {mu}{sub eff} are found to be interrelated by both measurements and calculations. The higher the {lambda} or the lower the {mu}{sub eff}, the higher bias field that is required for magneto-optical recording. The temperature independent {lambda} is demonstrated to be an important parameter in the assessment of magnetic properties and recording characteristics of sperimagnetic films. {copyright} {ital 1997 American Institute of Physics.}

  4. Nanostructured crystals of fluorite phases Sr{sub 1-x}R{sub x}F{sub 2+x}(R are rare-earth elements) and their ordering. I. Crystal growth of Sr{sub 1-x}R{sub x}F{sub 2+x} (R = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu)

    SciTech Connect

    Sobolev, B. P., E-mail: fluorides@ns.crys.ras.ru; Karimov, D. N.; Sul'yanov, S. N.; Zhmurova, Z. I. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2009-01-15

    Crystals of nonstoichiometric phases Sr{sub 1-x}R{sub x}F{sub 2+x} (R are 14 rare-earth elements) and the ordered phase Sr{sub 4}Lu{sub 3}F{sub 17} with a trigonally distorted fluorite lattice were grown by the Bridgman method. Ten of 26 Sr{sub 1-} {sub x}R{sub x}F{sub 2+x} crystals, where R = La-Ho or Y, melt congruently. The isoconcentration series Sr{sub 0.90}R{sub 0.10}F{sub 2.10} includes four crystals with R = Er-Lu. The compositions corresponding to the maxima for the latter crystals were not determined. The concentration series, in which the mole fraction of RF{sub 3} varies from 10 to 50 mol %, were obtained for the crystals with R = La, Nd, and Gd. Most of the crystals are of good optical quality. To evaluate the composition changes in the course of crystal growth, the cubic unit-cell parameters were determined by X-ray powder diffraction. The line-broadening analysis revealed a nonmonotonic change of microdistortions as regards both the rare-earth content and rare-earth series. The changes in the lattice parameters and the congruent-melting points of the Sr{sub 1-x}R{sub x}F{sub 2+x} phases in the rare-earth series reflect the morphotropic transitions in the series of pure RF{sub 3} despite the fact that SrF{sub 2} dominates in nonstoichiometric fluorite crystals.

  5. Fabrication of hollow and porous structured GdVO4:Dy3+ nanospheres as anticancer drug carrier and MRI contrast agent.

    PubMed

    Kang, Xiaojiao; Yang, Dongmei; Ma, Ping'an; Dai, Yunlu; Shang, Mengmeng; Geng, Dongling; Cheng, Ziyong; Lin, Jun

    2013-01-29

    Hollow and porous structured GdVO(4):Dy(3+) spheres were fabricated via a facile self-sacrificing templated method. The large cavity allows them to be used as potential hosts for therapeutic drugs, and the porous feature of the shell allows guest molecules to easily pass through the void space and surrounding environment. The samples show strong yellow-green emission of Dy(3+) (485 nm, (4)F(9/2) ? (6)H(15/2); 575 nm, (4)F(9/2) ? (6)H(13/2)) under UV excitation. The emission intensity of GdVO(4):Dy(3+) was weakened after encapsulation of anticancer drug (doxorubicin hydrochloride, DOX) and gradually restored with the cumulative released time of DOX. These hollow spheres were nontoxic to HeLa cells, while DOX-loaded samples led to apparent cytotoxicity as a result of the sustained release of DOX. ICP measurement indicates that free toxic Gd ions can hardly dissolate from the matrix. The endocytosis process of DOX-loaded hollow spheres is observed using confocal laser scanning microscopy (CLSM). Furthermore, GdVO(4):Dy(3+) hollow spheres can be used for T(1)-weighted magnetic resonance (MR) imaging. These results implicate that the luminescent GdVO(4):Dy(3+) spheres with hollow and porous structure are promising platforms for drug storage/release and MR imaging. PMID:23281806

  6. Magnetic and Moessbauer studies on GdCo/sub 3/B/sub 2/ and DyCo/sub 3/B/sub 2/

    SciTech Connect

    Malik, S.K.; Umarji, A.M.; Shenoy, G.K.

    1984-10-01

    Magnetization and Moessbauer studies have been carried out on GdCo/sub 3/B/sub 2/ and DyCo/sub 3/B/sub 2/. These compounds are magnetically ordered with Curie temperatures of 56/sup 0/ and 21/sup 0/K respectively. The Co atoms are either nonmagnetic or carry a small moment in these compounds. The saturation moment of DyCo/sub 3/B/sub 2/ at 5/sup 0/K is smaller than the Dy/sup 3 +/ free-ion value. From /sup 161/Dy Moessbauer studies, the measured hyperfine magnetic field at the Dy site is also observed to be smaller than the free-ion value. /sup 155/Gd Moessbauer measurements in GdCo/sub 3/B/sub 2/ reveal the presence of large crystalline electric fields at the rare earth site. This causes the moment and the hyperfine field at the Dy site in DyCo/sub 3/B/sub 2/ to be reduced from its free-ion value.

  7. Spectroscopic properties of Eu3+, Dy3+ and Tb3+ ions in lead silicate glasses obtained by the conventional high-temperature melt-quenching technique

    NASA Astrophysics Data System (ADS)

    ?ur, L.; Janek, J.; So?tys, M.; Pisarska, J.; Pisarski, W. A.

    2013-11-01

    The luminescence properties of selected rare-earth ions in lead silicate glasses have been studied. Europium, dysprosium and terbium ions were chosen as active dopants. Based on excitation and emission measurements as well as luminescence decay analysis, some spectroscopic parameters for these lanthanide ions were determined. In particular, the intensity ratios R/O (Eu3+), Y/B (Dy3+) and G/B (Tb3+) were calculated. Luminescence lifetimes for the 5D0 state of Eu3+ ions, the 4F9/2 state of Dy3+ ions and the 5D4 state of Tb3+ ions were also determined.

  8. Photoluminescence of Eu3+-, Tb3+-, Dy3+- and Tm3+-doped transparent GeO2 TiO2 K2O glass ceramics

    Microsoft Academic Search

    G. Lakshminarayana; Jianrong Qiu; M. G. Brik; I. V. Kityk

    2008-01-01

    In this paper, we present the photoluminescence properties of Eu3+-, Tb3+-, Dy3+- and Tm3+-doped potassium-titanium-germanate glasses and glass ceramics. Following the x-ray diffraction measurement, the glass structure was established. Compared to Eu3+-, Tb3+-, Dy3+- and Tm3+-doped glasses, their respective glass ceramics show stronger emissions due to the presence of the K2TiGe3O9 crystalline phase. For Eu3+-doped glass and glass ceramics, five

  9. OH bands in (Dy 1 ? x Gd x ) 3Ga 5O 12, Dy 3(Ga 1 ? y Al y ) 5O 12 and related oxides grown by the Czochralski method

    Microsoft Academic Search

    H. Kimura; V. V. Kochurikhin; K. Shimamura; T. Fukuda

    1996-01-01

    The OH bands at ? 3600 cm?1 in (Dy1 ? xGdx)3Ga5O12 and Dy3(Ga1 ? yAly)5O12 garnet single crystals have been measured at room temperature by Fourier-transform infrared spectroscopy for the first time. The noticeable OH bands were observed for the above garnets, whereas no corresponding bands were detected for Gd3Ga5O12 and Y3Ga5O12 garnets containing no Dy as a component. Based

  10. Rare-earth transition-metal chalcogenides Ln{sub 3}MGaS{sub 7} (Ln=Nd, Sm, Dy, Er; M=Co, Ni) and Ln{sub 3}MGaSe{sub 7} (Ln=Nd, Sm, Gd, Dy, M=Co; Ln=Nd, Gd, Dy, M=Ni)

    SciTech Connect

    Yin, Wenlong [Institute of Chemical Materials, China Academy of Engineering Physics, P.O. Box 919-306 Mianyang 621900 (China); Shi, Youguo [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Kang, Bin; Deng, Jianguo [Institute of Chemical Materials, China Academy of Engineering Physics, P.O. Box 919-306 Mianyang 621900 (China); Yao, Jiyong, E-mail: jyao@mail.ipc.ac.cn [Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Wu, Yicheng [Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-05-01

    Fifteen new rare-earth transition-metal chalcogenides, Ln{sub 3}MGaS{sub 7} (Ln=Nd, Sm, Dy, Er; M=Co, Ni) and Ln{sub 3}MGaSe{sub 7} (Ln=Nd, Sm, Gd, Dy, M=Co; Ln=Nd, Gd, Dy, M=Ni), have been synthesized by solid state reactions. They are isostructural, adopt Ce{sub 3}Al{sub 1.67}S{sub 7}—related structure type, and crystallize in the non-centrosymmetric hexagonal space group P6{sub 3}. They adopt a three-dimensional framework composed of LnQ{sub 7} monocapped trigonal prisms with the interesting [MQ{sub 3}]{sup 4?} chains and isolated GaQ{sub 4} tetrahedra lying in two sets of channels in the framework. The magnetic susceptibility measurements on Ln{sub 3}CoGaQ{sub 7} (Ln=Dy, Er, Q=S; Ln=Dy, Q=Se) indicate that they are paramagnetic and obey the Curie–Weiss law over the entire experimental temperature, while the magnetic susceptibility of Sm{sub 3}CoGaSe{sub 7} deviates from the Curie–Weiss law as a result of the crystal field splitting. - Graphical abstract: Ln{sub 3}MGaS{sub 7} (Ln=Nd, Sm, Dy, Er; M=Co, Ni) and Ln{sub 3}MGaSe{sub 7} (Ln=Nd, Sm, Gd, Dy, M=Co; Ln=Nd, Gd, Dy, M=Ni) adopt a three-dimensional framework composed of LnQ{sub 7} monocapped trigonal prisms with interesting [MQ{sub 3}]{sup 4?} chains and isolated GaQ{sub 4} tetrahedra lying in two sets of channels in the framework. - Highlights: • New compounds, Ln{sub 3}MGaQ{sub 7} (Ln=rare-earth; M=Co, Ni; Q=S, Se), were synthesized. • They are isostructural and crystallize in the noncentrosymmetric space group P6{sub 3}. • They adopt a three-dimensional framework built by LnQ{sub 7} monocapped trigonal prisms. • Ln{sub 3}CoGaQ{sub 7} (Ln=Dy, Er; Q=S, Se) are paramagnetic and obey the Curie–Weiss law. • The magnetic susceptibility of Sm{sub 3}CoGaSe{sub 7} deviates from the Curie–Weiss law.

  11. Crystalline structure, magnetic response and electronic properties of RE2MgTiO6 (RE = Dy, Gd) double perovskites

    NASA Astrophysics Data System (ADS)

    Landínez Téllez, D. A.; Martínez Buitrago, D.; Cardona C, R.; Barrera, E. W.; Roa-Rojas, J.

    2014-06-01

    The synthesis, crystal structure, morphology, magnetic properties and electronic calculations of two members of the family of double perovskite materials RE2MgTiO6 (RE = Dy, Gd) are described. X-ray powder diffraction measurements show that these materials crystallize in monoclinic perovskite structures with space group P21/n (#14). Unit cell parameters, atomic positions, tilt angle, inter-atomic distances and site occupancies were calculated by Rietveld through the GSAS code reveal. Lattice parameters for Dy2MgTiO6 were a = 5.3624(4) Å, b = 5.5973(2) Å and c = 7.6794(2) Å, and for Gd2MgTiO6a = 5.3143(5) Å, b = 5.5826(2) Å and c = 7.6324(2) Å. Samples morphology analyzed by scanning electron microscopy reveal strongly coupled grains with mean size 3 ?m. Paramagnetic behavior is evidenced by magnetic susceptibility measurements and Curie-Weiss fitting supplies effective magnetic moments which lay 98% in agreement with the theoretical predictions for the isolated rare earth elements for each compound.

  12. Ionic Transport Properties in Nanocrystalline Ce0.8A0.2O2-? (with A = Eu, Gd, Dy, and Ho) Materials

    PubMed Central

    2010-01-01

    The ionic transport properties of nanocrystalline 20 mol% Eu, Gd, Dy, and Ho doped cerias, with average grain size of around 14 nm were studied by correlating electrical, dielectric properties, and various dynamic parameters. Gd-doped nanocrystalline ceria shows higher value of conductivity (i.e., 1.8 × 10?4 S cm?1 at 550°C) and a lower value of association energy of oxygen vacancies with trivalent dopants Gd3+ (i.e., 0.1 eV), compared to others. Mainly the lattice parameters and dielectric constants (??) are found to control the association energy of oxygen vacancies in these nanomaterials, which in turn resulted in the presence of grain and grain boundary conductivity in Gd- and Eu-doped cerias and only significant grain interior conductivity in Dy- and Ho-doped cerias. PMID:20671782

  13. Photoluminescence properties of aeschynite-type LaNbTiO6:RE3+ (RE = Tb, Dy, Ho) down-converting phosphors.

    PubMed

    Ma, Qian; Lu, Mengkai; Yang, Ping; Zhang, Aiyu; Cao, Yongqiang

    2014-06-01

    In this study, a series of LaNbTiO6:RE(3+) (RE = Tb, Dy, Ho) down-converting phosphors were synthesized using a modified sol-gel combustion method, and their photoluminescence (PL) properties were investigated as a function of activator concentration and annealing temperature. The resultant particles were characterized using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, UV/Vis diffuse reflectance spectroscopy and PL spectra. The highly crystalline LaNbTiO6:RE(3+) (RE = Tb, Dy, Ho) phosphors with an average size of 200-300 nm obtained at 1100°C have an orthorhombic aeschynite-type structure and exhibit the highest luminescent intensity in our study range. The emission spectra of LaNbTiO6:RE(3+) (RE = Tb, Dy, Ho) phosphors under excitations at UV/blue sources are mainly composed of characteristic peaks arising from the f-f transitions of RE(3+), including 489 nm ((5) D4 ? (7) F6) and 545 nm ((5) D4 ? (7) F5) for Tb(3+), 476 and 482 nm ((4) F9/2 ? (6) H15/2) and 571 nm ((4) F9/2 ? (6) H13/2) for Dy(3+), and 545 nm ((5) F4 +?(5) S2 ? (5) I8) for Ho(3+), respectively. The luminescent mechanisms were further investigated. It can be expected that these phosphors are of intense interest and potential importance for many optical applications. PMID:23868821

  14. Separating Ag, B, Cd, Dy, Eu, and Sm in a Gd matrix using 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester extraction chromatography for ICP-AES analysis.

    PubMed

    Choi, Kwang-Soon; Lee, Chang-Heon; Kim, Jong-Goo; Kim, Won-Ho; Kang, Jun-Gill

    2007-02-15

    The separation procedure for Ag, B, Cd, Dy, Eu and Sm as impurities in Gd matrix using ICP-AES technique with an extraction chromatographic column has been developed. The spectral interference of the Gd matrix on the elements was eliminated using a chromatography technique with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A) as the mobile phase and XAD-16 resin as the stationary phase. Ag(+), B(4)O(7)(2-), and Cd(2+) were eluted with 0.1M HNO(3), while rare earth ions were not. The best eluent for separating Eu and Sm in the Gd matrix was 0.3M HNO(3). The limit of quantitation for these elements was 0.6-3.0ng mL(-1). The recovery of Ag, B, and Cd was 90-104% using 0.1M HNO(3) as the eluent, while that of Eu, Gd, and Sm ranged from 100 to 102% with 0.3M HNO(3). Dy was recovered quantitatively with 4M HNO(3). The relative standard deviation of the methods for a set of three replicates was between 1.0 and 15.4% for the synthetic and standard Gd solutions. The proposed separation procedure was used to measure Ag, B, Cd, Dy, Eu, and Sm in a standard Gd solution. PMID:19071357

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

    SciTech Connect

    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.

  16. Preparation of cereal-like YVO(4):Ln(3+) (Ln = Sm, Eu, Tb, Dy) for high quantum efficiency photoluminescence.

    PubMed

    Li, Liping; Zhao, Minglei; Tong, Wenming; Guan, Xiangfeng; Li, Guangshe; Yang, Liusai

    2010-05-14

    In this work, preparation of cereal-like architectures Y V O(4) and Y V O(4):Ln(3 + ) (Ln = Eu, Sm, Dy, Tb) was initiated using a hydrothermal method. During the formation reaction, Na(3)C(6)H(5)O(7).2H(2)O was used to effectively adjust the concentration of Y(3 + ) species necessary for cereal-like architectures. Phase structure, surface chemistry, morphology, and photoluminescence were characterized by x-ray powder diffraction, Fourier transformed infrared spectra, scanning electron microscopy, transmission electron microscopy, and photoluminescence spectra. All samples crystallize in a tetragonal zircon structure, stably showing a homogeneous cereal-like morphology. This special morphology was constructed by self-assembly of tiny primary particles with a dimension of 31-32 nm. With increasing atomic number of Ln(3 + ), the lattice dimension of the cereal architectures became monotonously enlarged. This cereal-like architecture is proved unique in significantly improving the quantum efficiencies: the internal quantum efficiencies of (5)D(0) for Ln = Eu and (4)F(9/2) for Ln = Dy were 14.6% and 11.4%, respectively, which are all superior over those of the counterparts of nanoparticles reported in the literature. The average lifetime of the (5)D(0) level for Ln = Eu was calculated to be 98 micros, which is longer than that of 50 micros of the (4)F(9/2) level for Ln = Dy. The strong photoluminescence might be the consequence of the effective energy transfer due to the greatly reduced defect centers from this special self-assembly structure. PMID:20400814

  17. Couples Magnetic and Structural Transitions in High-Purity Dy and Gd5SbxGe4-x

    SciTech Connect

    Alexander S. Chernyshov

    2006-08-09

    Magnetic materials exhibiting magnetic phase transitions simultaneously with structural rearrangements of their crystal lattices hold a promise for numerous applications including magnetic refrigeration, magnetomechanical devices and sensors. We undertook a detailed study of a single crystal of dysprosium metal, which is a classical example of a system where magnetic and crystallographic sublattices can be either coupled or decoupled from one another. Magnetocaloric effect, magnetization, ac magnetic susceptibility, and heat capacity of high purity single crystals of dysprosium have been investigated over broad temperature and magnetic field intervals with the magnetic field vector parallel to either the a- or c-axes of the crystal. Notable differences in the behavior of the physical properties when compared to Dy samples studied in the past have been observed between 110 K and 125 K, and between 178 K and {approx}210 K. A plausible mechanism based on the formation of antiferromagnetic clusters in the impure Dy has been suggested in order to explain the reduction of the magnetocaloric effect in the vicinity of the Neel point. Experimental and theoretical investigations of the influence of commensurability effects on the magnetic phase diagram and the value of the magnetocaloric effect have been conducted. The presence of newly found anomalies in the physical properties has been considered as evidence of previously unreported states of Dy. The refined magnetic phase diagram of dysprosium with the magnetic field vector parallel to the a-axis of a crystal has been constructed and discussed. The magnetic and crystallographic properties of Gd{sub 5}Sb{sub x}Ge{sub 4-x} pseudo-binary system were studied by x-ray diffraction (at room temperature), heat capacity, ac-magnetic susceptibility, and magnetization in the temperature interval 5-320 K in magnetic fields up to 100 kOe. The magnetic properties of three composition (x = 0.5, 1,2) were examined in detail. The Gd{sub 5}Sb{sub 2}Ge{sub 2} compound that adopts Tm{sub 5}Sb{sub 2}Si{sub 2}-type of structure (space group is Cmca), shows a second order FM-PM transition at 200 K, whereas Gd{sub 5}Sb{sub x}Ge{sub 4-x} compounds for x = 0.5 and x = 1 (Sm{sub 5}Ge{sub 4}-type of structure, space group is Pnma) exhibit first order phase transformations at 45 K and 37 K, respectively.

  18. Study on energy transfer and energy migration of Ca2Gd8(SiO4)6O2:Dy3+ phosphor films.

    PubMed

    Wang, X Q; Han, X M; Zhen, C M

    2011-11-01

    Being a kind of rare-earth-metal silicate with oxidapatite structure, Ca2R8(SiO4)6O2 (R = Y, Gd, La) is a promising material doped with rare earth, and widely used as phosphors. In this thesis, Ca2Gd8(SiO4)6O2:Dy3+ films were prepared by the sol-gel method. X-ray diffraction (XRD), atomic force microscopy (AFM), photoluminescence (PL) spectra, and lifetimes were used to characterize the resulting films. AFM study indicated that the phosphor films consisted of 120 nm homogeneous particles. By combining the model of Burshtein for donor-donor migration and the V-F-B model for donor-acceptor energy transfer, the experimental luminescence decay curve of 6P(J) state of Gd3+ was re-simulated. It is found that concentration quenching of Gd3+ can be due to the result of the joint action of donor-donor (Gd3+-Gd3+) energy migration and donor-acceptor (Gd3+-Dy3+) energy transfer. PMID:22413278

  19. MAGNETOSTRICTION AND ANISOTROPY IN Tb x Dy 1 - x SINGLE CRYSTALS

    Microsoft Academic Search

    M. L. Spano; A. E. Clark; J. P. Teter; J. R. Cullen

    1988-01-01

    Magnetostriction and differential scanning calorimetry measurements have been made on the Tb,Dyl-, alloy system. Measurements spanning the ferromagnetic, antiferromagnetic spiral, and paramagnetic states were made from 56 K to 300 K in fields of 6 20 kOe. The two lowest order magnetostridion constants were determined, as was the basal plane anisotropy. The anisotropy was found to compensate at finite temperatures

  20. Microdome-gooved Gd(2)O(2)S:Tb scintillator for flexible and high resolution digital radiography.

    PubMed

    Jung, Phill Gu; Lee, Chi Hoon; Bae, Kong Myeong; Lee, Jae Min; Lee, Sang Min; Lim, Chang Hwy; Yun, Seungman; Kim, Ho Kyung; Ko, Jong Soo

    2010-07-01

    A flexible microdome-grooved Gd(2)O(2)S:Tb scintillator is simulated, fabricated, and characterized for digital radiography applications. According to Monte Carlo simulation results, the dome-grooved structure has a high spatial resolution, which is verified by X-ray image performance of the scintillator. The proposed scintillator has lower X-ray sensitivity than a nonstructured scintillator but almost two times higher spatial resolution at high spatial frequency. Through evaluation of the X-ray performance of the fabricated scintillators, we confirm that the microdome-grooved scintillator can be applied to next-generation flexible digital radiography systems requiring high spatial resolution. PMID:20639972

  1. ELECTRON PARAMAGNETIC RESONANCE SPECTRA OF Er(III), Dy(III), AND Gd(III) IN YTTRIUM AND LANTHANUM HYDRIDES

    SciTech Connect

    Spencer, Brock; Edelstein, Norman M.

    1980-12-01

    The present study was undertaken to confirm the oxidation state of the metal and the hydridic nature of the hydrogen in metal hydrides by obtaining electron paramagnetic resonance (EPR) parameters sensitive to the oxidation state of the metal and to the sign of the charge on the hydrogen for representative lanthanides (Er, Dy, and Gd) diluted in the nonmagnetic host materials YH{sub x} and LaH{sub x}. For hydride compositions near x = 2.0, the environment of the dopant metal ion should be cubic for the majority of the ions present, thus providing a convenient situation for determining the oxidation state and electronic ground state of the ion in question so as to distinguish between protonic and hydridic crystalline electric fields.

  2. Photoluminescence of zircon (ZrSiO4) doped with REE3+ (REE = Pr, Sm, Eu, Gd, Dy, Ho, Er)

    NASA Astrophysics Data System (ADS)

    Friis, Henrik; Finch, Adrian A.; Williams, C. Terry; Hanchar, John M.

    2010-06-01

    The photoluminescence properties of synthetic zircon, ZrSiO4, doped with REE3+ (REE = Pr, Sm, Eu, Gd, Dy, Ho, Er) were investigated using combined excitation and emission spectroscopy. All samples showed luminescence characteristics of intra-ion energy transitions, similar to other lanthanide-doped materials. However, the relative intensities were dependent on the energy of excitation and the presence of charge-transfer bands were inferred from excitation spectra. From the data, we conclude that the lanthanides in zircon occur in more than one type of coordination. Energy transfer between different lanthanides was observed in some co-doped samples and emissions that were unassigned in previous studies have been assigned to specific lanthanides based on excitation spectroscopy.

  3. Large magnetocaloric effects of RFeSi (R = Tb and Dy) compounds for magnetic refrigeration in nitrogen and natural gas liquefaction

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Sun, Y. J.; Niu, E.; Yang, L. H.; Shen, J.; Hu, F. X.; Sun, J. R.; Shen, B. G.

    2013-11-01

    Magnetic properties and magnetocaloric effect (MCE) of intermetallic RFeSi (R = Tb and Dy) compounds have been investigated systematically. The RFeSi compounds undergo a second-order magnetic transition from ferromagnetic to paramagnetic states with the variation of temperature. The Curie temperatures determined from magnetization measurements are 110 K and 70 K for TbFeSi and DyFeSi, respectively, which are quite close to the liquefaction temperatures of natural gas (111 K) and nitrogen (77 K). Both compounds exhibit nearly same large MCE around their respective ordering temperatures. For a low magnetic field change of 1 T, the maximum values of magnetic entropy change -?SM and adiabatic temperature change ?Tad are 5.3 J/kg K and 2.1 K for TbFeSi, 4.8 J/kg K and 1.7 K for DyFeSi, respectively. Furthermore, a composite material based on (Tb1-xDyx)FeSi compounds is designed theoretically by using a numerical method, and it exhibits a constant -?Scom of ˜1.4 J/kg K for a field change of 1 T in the wide temperature range of 67-108 K, satisfying the requirement of Ericsson-cycle magnetic refrigeration over the liquefaction temperatures of nitrogen and natural gas.

  4. Hydrothermal derived LaOF:Ln3+ (Ln = Eu, Tb, Sm, Dy, Tm, and/or Ho) nanocrystals with multicolor-tunable emission properties.

    PubMed

    Shang, Mengmeng; Geng, Dongling; Kang, Xiaojiao; Yang, Dongmei; Zhang, Yang; Lin, Jun

    2012-10-15

    A series of LaOF:Ln(3+) (Ln = Eu, Tb, Sm, Dy, Tm, and/or Ho) nanocrystals with good dispersion have been successfully prepared by the hydrothermal method followed a heat-treatment process. Under ultraviolet radiation and low-voltage electron beam excitation, the LaOF:Ln(3+) nanocrystals show the characteristic f-f emissions of Ln(3+) (Ln = Eu, Tb, Sm, Dy, Tm, or Ho) and give red, blue-green, orange, yellow, blue, and green emission, respectively. Moreover, there exists simultaneous luminescence of Tb(3+), Eu(3+), Sm(3+), Dy(3+), Tm(3+), or Ho(3+) individually when codoping them in the single-phase LaOF host (for example, LaOF:Tb(3+), Eu(3+)/Sm(3+); LaOF:Tm(3+), Dy(3+)/Ho(3+); LaOF:Tm(3+), Ho(3+), Eu(3+) systems), which is beneficial to tune the emission colors. Under low-voltage electron beam excitation, a variety of colors can be efficiently adjusted by varying the doping ions and the doping concentration, making these materials have potential applications in field-emission display devices. More importantly, the energy transfer from Tm(3+) to Ho(3+) in the LaOF:Tm(3+), Ho(3+) samples under UV excitation was first investigated and has been demonstrated to be a resonant type via a quadrupole-quadrupole mechanism. The critical distance (R(Tm-Ho)) is calculated to be 28.4 Å. In addition, the LaOF:Tb(3+) and LaOF:Tm(3+) phosphors exhibit green and blue luminescence with better chromaticity coordinates, color purity, and higher intensity compared with the commercial green phosphor ZnO:Zn and blue phosphor Y(2)SiO(5):Ce(3+) to some extent under low-voltage electron beam excitation. PMID:23020114

  5. Hot-electron-driven enhancement of spin-lattice coupling in Gd and Tb 4f ferromagnets observed by femtosecond x-ray magnetic circular dichroism.

    PubMed

    Wietstruk, Marko; Melnikov, Alexey; Stamm, Christian; Kachel, Torsten; Pontius, Niko; Sultan, Muhammad; Gahl, Cornelius; Weinelt, Martin; Dürr, Hermann A; Bovensiepen, Uwe

    2011-03-25

    Femtosecond x-ray magnetic circular dichroism was used to study the time-dependent magnetic moment of 4f electrons in the ferromagnets Gd and Tb, which are known for their different spin-lattice coupling. We observe a two-step demagnetization with an ultrafast demagnetization time of 750 fs identical for both systems and slower times which differ sizeably with 40 ps for Gd and 8 ps for Tb. We conclude that spin-lattice coupling in the electronically excited state is enhanced up to 50 times compared to equilibrium. PMID:21517350

  6. Exchange and crystal-field interactions in the antiferromagnets GdRh2Si2 and TbRh2Si2

    Microsoft Academic Search

    A. Szytula; R. J. Radwanski; F. R. de Boer

    1992-01-01

    Magnetization curves up to 35 T have been measured at 4.2 K on free powder particles of the antiferromagnets GdRh2Si2 and TbRh2Si2. The magnetization process is analyzed within a two-sublattice model for antiferromagnets. For GdRh2Si2 the intersublattice molecular-field coefficient amounts to 7.2 T f.u.\\/muB. For TbRh2Si2 metamagnetic transitions at 8 and 15 T are observed.

  7. Magnetic and magnetoelastic studies of single crystal Tb{sub 0.6}Dy{sub 0.4}Zn at low temperatures

    SciTech Connect

    Cullen, J.R. [Dublin Univ. (Ireland)] [Dublin Univ. (Ireland); Teter, J.P.; Wun-Fogle, M.; Restorff, J.B. [Naval Surface Warfare Center, Bethesda, MD (United States). Carderock Div.] [Naval Surface Warfare Center, Bethesda, MD (United States). Carderock Div.; Clark, A.E. [Clark Associates, Adelphia, MD (United States)] [Clark Associates, Adelphia, MD (United States)

    1997-09-01

    The alloys series Tb{sub 1{minus}x}Dy{sub x}Zn, x {le} 0.6, has been shown to undergo easy-axis reorientations at low temperatures. In this paper results of magnetization on single crystal disks of Tb{sub 0.6}Dy{sub 0.4}Zn are reported. Maxima in the magnetization as much as 15{degree} from the <100> axes were found below T{sub R} {approx_equal} 20 K. Magnetostrictions of 5 {times} 10{sup {minus}3} were measured at 77 K on single crystal rods. Magnetization versus field curves under a series of compressive stresses have verified the highly magnetoelastic nature of this alloy. The non-principal magnetization orientations are discussed on a phenomenological model which includes an eighth-order anisotropy term.

  8. Thermoluminescence properties of isostructural K 2YF 5 and K 2GdF 5 crystals doped with Tb 3+ in response to ?, ? and X-ray irradiation

    NASA Astrophysics Data System (ADS)

    Hanh, Huynh Ky; Khaidukov, Nicholas M.; Makhov, Vladimir N.; Quang, Vu Xuan; Thanh, Nguyen Trong; Tuyen, Vu Phi

    2010-10-01

    The thermoluminescence (TL) properties of isostructural fluoride K 2YF 5 and K 2GdF 5 crystals doped with Tb 3+ of different concentrations have been studied in the temperature range from 30 to 500 °C after ?, ? and X-ray irradiation. Strongly different structures of TL glow curves following ? or ? irradiation have been found for Tb 3+ doped K 2YF 5 for all studied concentrations of Tb 3+ whereas for K 2GdF 5 crystals the different TL curves after ? or ? irradiation are detected only for heavily doped samples. On the other hand, all the studied materials show similar TL glow curves after ? or X-ray irradiation. It has been discovered that K 2YF 5 doped with 1 at.% Tb 3+ has TL radiation sensitivity to ? irradiation of the same order as that of the well known TLD-100 (LiF:Mg,Ti) phosphor and much higher sensitivity to ? irradiation. The TL mechanism in K 2YF 5 and K 2GdF 5 doped with Tb 3+ is discussed by taking into account the TL emission spectra from irradiated samples, which are identical to the emission spectra of the Tb 3+ ions in these hosts under photo-excitation, and the kinetics parameters obtained with the method of various heating rates.

  9. Vibrational structure in optical spectra of the Ca 4GdO(BO 3) 3 (GdCOB) single crystal doped with Re 3+ (Eu, Tb, Yb)

    NASA Astrophysics Data System (ADS)

    Dominiak-Dzik, G.; Ryba-Romanowski, W.; Go??b, S.; Baba, M.; Paj?czkowska, A.

    2002-09-01

    The optical spectra of compounds containing trivalent rare earth (Re 3+) ions often show vibronic features. The intensity of vibronic transitions is determined by the strength of the electron-phonon (ion-lattice) coupling and depends strongly on the rare earth and the host lattice. In this paper we report on electron-phonon coupling in the GdCOB system doped with Eu 3+, Tb 3+ and Yb 3+ ions. According to general theory intense vibronic lines are to be expected for electronic transitions with ? J=0, ±2 and these transitions were mainly considered in this paper for both Eu 3+ and Tb 3+ ions. In the case of Yb 3+ ions, a strong vibronic sideband belongs to the 2F 7/2? 2F 5/2 transition with ? J=1 although it seems to be in contradiction to the general selection rule. The vibronic features observed in absorption, excitation and emission spectra were analysed on the basis of the host lattice modes obtained from Raman and the far infrared spectra of the matrix.

  10. Influence of ionic sizes of rare earths on thermoelectric properties of perovskite-type rare earth cobalt oxides RCoO 3 (R = Pr, Nd, Tb, Dy)

    Microsoft Academic Search

    Hideki Hashimoto; Takafumi Kusunose; Tohru Sekino

    2009-01-01

    Perovskite-type rare earth cobalt oxide RCoO3 (R=Pr, Nd, Tb, Dy) ceramics were prepared by reaction sintering of corresponding metal oxide powders, and their thermoelectric performances were evaluated up to 873K. The electrical conductivity of RCoO3 increased with increasing temperature while the Seebeck coefficient decreased, which was a typical semiconducting characteristic. The conductivity and the Seebeck coefficient also depend on the

  11. Single-Particle and Collective Mode Couplings Associated with 1-and 2-Directional Electronic Ordering in Metallic RTe3 (R Ho; Dy; Tb)

    E-print Network

    Fisher, Ian

    Ordering in Metallic RTe3 (R ¼ Ho; Dy; Tb) R. V. Yusupov,1,* T. Mertelj,1 J.-H. Chu,2 I. R. Fisher,2 and D) electronically driven charge-density wave (CDW) ordering in metallic RTe3 is investigated as a function of rare and is not clear. Layered rare-earth tritelluride compounds (RTe3, where R is a rare-earth ion) shown schematically

  12. Magnetocrystalline anisotropy and magnetostriction of H and N modified R 2Fe 17 compounds (R=Y, Tb, Dy, Ho, Er)

    Microsoft Academic Search

    S. A Nikitin; E. A Ovtchenkov; I. S Tereshina; A. A Salamova; V. N Verbetsky

    1999-01-01

    The effects of the hydrogen and the nitrogen on the magnetocrystalline anisotropy (MCA) and magnetostriction of R2Fe17M (R=Y, Tb, Dy, Ho, Er; M=H, N) compounds are studied. The signs of the first MCA constants of a rare-earth (R) sublattice are in agreement with the sign of the Stevens factors of R ions for all R2Fe17M compounds studied. The effects of

  13. Effect of interstitial hydrogen and nitrogen on the magnetocrystalline anisotropy of R 2Fe 17 (R=Tb,Dy,Ho,Er)

    Microsoft Academic Search

    S. A. Nikitin; E. A. Ovtchenkov; A. A. Salamova; A. Yu. Sokolov; V. N. Verbetsky

    1997-01-01

    The magnetocrystalline anisotropies of R2Fe17 (R=Tb,Dy,Ho and Er) and of the nitrides and hydrides of these compounds are studied by analysing the hard and the easy magnetization curves of magnetically aligned samples in the temperature range 80–300 K. The effects of the hydrogen and the nitrogen atoms on the rare earth sublattice anisotropy are found to be opposite. It is

  14. Magnetocrystalline anisotropy and magnetostriction of H and N modified R2Fe17 compounds (R=Y, Tb, Dy, Ho, Er)

    Microsoft Academic Search

    S. A. Nikitin; E. A. Ovtchenkov; I. S. Tereshina; A. A. Salamova; V. N. Verbetsky

    1999-01-01

    The effects of the hydrogen and the nitrogen on the magnetocrystalline anisotropy (MCA) and magnetostriction of R2Fe17M (R=Y, Tb, Dy, Ho, Er; M=H, N) compounds are studied. The signs of the first MCA constants of a rare-earth (R) sublattice are in agreement with the sign of the Stevens factors of R ions for all R2Fe17M compounds studied. The effects of

  15. Synthesis and photoluminescence characteristics of Ln3+ (Ln = Sm, Er and Dy)-doped BaGd2(MoO4)4 phosphors

    NASA Astrophysics Data System (ADS)

    Deng, Yaomin; Yi, Shuangping; Wang, Yinhai; Xian, Jieqiang

    2014-06-01

    BaGd2(MoO4)4 phosphor powders activated with the trivalent rare-earth Ln3+ (Ln = Sm, Er and Dy) were synthesized by a traditional high temperature solid-state reaction. The resulted phosphors were characterized by X-ray diffraction (XRD) and photoluminescence (PL) spectroscopy. XRD results demonstrate that Ln3+-doped samples can be well indexed to the pure monoclinic scheelite-type structure BaGd2(MoO4)4. The photoluminescence investigations revealed that the phosphors exhibit apparent characteristic emissions from the 4G5/2 to 6H5/2, 7/2, 9/2 state for Sm3+, 2H11/2 and 4S3/2 state to the 4I15/2 ground state for Er3+, 4I15/2, 4F9/2 to 6H15/2 and 4F9/2 to 6H13/2 for Dy3+ under near ultraviolet excitation. BaGd1.95(MoO4)4:0.05Sm3+, BaGd1.93(MoO4)4:0.07Er3+ and BaGd1.90(MoO4)4:0.10Dy3+ emit bright orange-red, green and white light with the CIE coordinates of (0.5381, 0.4544), (0.2307, 0.6096) and (0.3314, 0.3853) respectively. The sharp emission peaks and excellent luminescence properties show that BaGd2(MoO4)4 is a suitable host for rare earth doped phosphors, which may be potentially applied in the applications of the optical materials.

  16. Highly bright multicolor tunable ultrasmall ?-Na(Y,Gd)F4:Ce,Tb,Eu/?-NaYF4 core/shell nanocrystals

    NASA Astrophysics Data System (ADS)

    Kim, Su Yeon; Woo, Kyoungja; Lim, Kipil; Lee, Kwangyeol; Jang, Ho Seong

    2013-09-01

    Herein, we report highly bright multicolor-emitting ?-Na(Y,Gd)F4:Ce,Tb,Eu/?-NaYF4 nanoparticles (NPs) with precise color tunability. First, highly bright sub-20 nm ?-Na(Y,Gd)F4:Ce,Tb,Eu NPs were synthesized via a heating-up method. By controlling the ratio of Eu3+ to Tb3+, we generated green, yellow-green, greenish yellow, yellow, orange, reddish orange, and red emissions from the NP solutions via energy transfer of Ce3+ --> Gd3+ --> Tb3+ (green) and Ce3+ --> Gd3+ --> Tb3+ --> Eu3+ (red) ions under ultraviolet light illumination (254 nm). Because of Ce3+ and Gd3+ sensitization, Tb3+ ions exhibited strong green emission. The decay time of Tb3+ emission decreased from 4.0 to 1.4 ms as the Eu3+ concentration was increased, suggesting that energy was transferred from Tb3+ to Eu3+. As a result, Eu3+ emission peaks were generated and the emission color was transformed from green to red. Monodisperse sub-6 nm ?-Na(Y,Gd)F4:Ce,Tb,Eu NPs were synthesized through a simple reduction of the reaction temperature. Although fine color tunability was retained, their brightness was considerably decreased owing to an increase in the surface-to-volume ratio. The formation of a ?-NaYF4 shell on top of the sub-6 nm NP core to produce ?-Na(Y,Gd)F4:Ce,Tb,Eu/?-NaYF4 significantly increased the emission intensity, while maintaining the sub-10 nm sizes (8.7-9.5 nm). Quantum yields of the ultrasmall NPs increased from 1.1-6.9% for the core NPs to 6.7-44.4% for the core/shell NPs. Moreover, highly transparent core/shell NP-polydimethylsiloxane (PDMS) composites featuring a variety of colors, excellent color tunability, and high brightness were also prepared.Herein, we report highly bright multicolor-emitting ?-Na(Y,Gd)F4:Ce,Tb,Eu/?-NaYF4 nanoparticles (NPs) with precise color tunability. First, highly bright sub-20 nm ?-Na(Y,Gd)F4:Ce,Tb,Eu NPs were synthesized via a heating-up method. By controlling the ratio of Eu3+ to Tb3+, we generated green, yellow-green, greenish yellow, yellow, orange, reddish orange, and red emissions from the NP solutions via energy transfer of Ce3+ --> Gd3+ --> Tb3+ (green) and Ce3+ --> Gd3+ --> Tb3+ --> Eu3+ (red) ions under ultraviolet light illumination (254 nm). Because of Ce3+ and Gd3+ sensitization, Tb3+ ions exhibited strong green emission. The decay time of Tb3+ emission decreased from 4.0 to 1.4 ms as the Eu3+ concentration was increased, suggesting that energy was transferred from Tb3+ to Eu3+. As a result, Eu3+ emission peaks were generated and the emission color was transformed from green to red. Monodisperse sub-6 nm ?-Na(Y,Gd)F4:Ce,Tb,Eu NPs were synthesized through a simple reduction of the reaction temperature. Although fine color tunability was retained, their brightness was considerably decreased owing to an increase in the surface-to-volume ratio. The formation of a ?-NaYF4 shell on top of the sub-6 nm NP core to produce ?-Na(Y,Gd)F4:Ce,Tb,Eu/?-NaYF4 significantly increased the emission intensity, while maintaining the sub-10 nm sizes (8.7-9.5 nm). Quantum yields of the ultrasmall NPs increased from 1.1-6.9% for the core NPs to 6.7-44.4% for the core/shell NPs. Moreover, highly transparent core/shell NP-polydimethylsiloxane (PDMS) composites featuring a variety of colors, excellent color tunability, and high brightness were also prepared. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr02591h

  17. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: A novel Dy3+-doped GdPO4 white-light phosphors under vacuum ultraviolet excitation for Hg-free lamps application

    NASA Astrophysics Data System (ADS)

    Han, Guo-Cai; Wang, Yu-Hua; Wu, Chun-Fang; Zhang, Jia-Chi

    2009-10-01

    Novel Dy3+-doped GdPO4 white light phosphors with monoclinic system were successfully synthesised by hydrothermal method at 240 °C. This paper investigates the luminescence properties of white-light Gd1-xPO4:xDy3+ under vacuum ultraviolet (VUV) excitation. The strong absorption at around 147 nm in excitation spectrum energy can be transferred to the energy levels of Dy3+ ion from the host absorption. Additionally, this white light phosphors are activated by a single Dy3+ ion and with a lower preparation temperature, which tend to decrease the consumption of rare earth resource and energy. Therefore, the luminescence of Gd1-xPO4:xDy3+ under VUV excitation is effective, and proves to be promising in application to mercury-free lamp.

  18. Crystal structure of Tb5Ni2In4 and Y5Ni2In4, and magnetic properties of Dy5Ni2In4

    SciTech Connect

    Provino, A.; Mudryk, Y.; Smetana, V.; Manfrinetti, P.; Pecharsky, V.K.; Gschneidner Jr, Karl; Corbett, J.D.

    2012-02-27

    The crystal structure of the R5Ni2In4 intermetallic compounds was earlier reported for R Ho, Er, Tm, and Lu (Lu5Ni2In4-type, oP22, Pbam); more recently the isostructural phases Dy5Ni2In4 and Sc5Ni2In4 have also been identified. Three inequivalent crystallographic sites are occupied by the R atoms in these compounds. We have synthesized and characterized Dy5Ni2In4 and the two new isotypic compounds Tb5Ni2In4 and Y5Ni2In4. So far, none of the physical properties have been reported on any of these phases; in this article we report on the physical properties of the Dy5Ni2In4 and the crystal structure of Tb5Ni2In4 and Y5Ni2In4 compounds. Measurements of the magnetic properties performed on Dy5Ni2In4 show a ferromagnetic-like ordering with a T-C approximate to 105 K, followed by multiple magnetic orderings at lower temperatures. The fit of the inverse susceptibility in the paramagnetic state follows the Curie-Weiss law, where mu(eff). - 10.3 mu(B)/Dy-atom (close to theoretical value of 10.64 mu(B) for the free ion Dy3+) and a positive paramagnetic Curie temperature theta(p) - 58 K. Ni atoms are most likely to be nonmagnetic. The heat capacity also shows three peaks: a large one at 103K and two weaker at 12 and 8 K, respectively; the in-field heat capacity data corroborate these results, suggesting ferromagnetic and antiferromagnetic orderings at the temperature of 103 and 12 K, respectively. Low temperature x-ray diffraction has shown that the compound does not undergo any structural change down to 5K. (C) 2012 American Institute of Physics

  19. Bifunctional supramolecular systems on the platform of p-sulfonatothiacalix[4]arene containing photochromic mononitrosyl Ru (II) and paramagnetic aqua Gd or Dy complexes

    NASA Astrophysics Data System (ADS)

    Kushch, L. A.; Yagubskii, E. B.; Dmitriev, A. I.; Morgunov, R. B.; Emel'Yanov, V. A.; Mustafina, A. R.; Gubaidullin, A. T.; Burilov, V. A.; Solovieva, S. E.; Schaniel, D.; Woike, Th.

    2010-06-01

    Two bifunctional supramolecular systems [RuNO(NH3)4OH]2+·[RuNO(NH3)4H2O]3+·Gd3+(H2O)6·2[TCAS]4-·4H2O (1) and [RuNO(NH3)4OH]2+·[RuNO(NH3)4H2O]3+·Dy3+(H2O)6·2[TCAS]4-·4H2O (2) on the platform of p-sulfonatothiacalix[4]arene containing photochromic mononitrosyl Ru and paramagnetic rare-earth (Gd3+, Dy3+) cations have been synthesized. The crystal structures of 1 and 2 are discussed. Their photochromic, magnetic and photomagnetic properties studied by IR and SQUID experimental techniques are presented

  20. Bifunctional supramolecular systems on the platform of p-sulfonatothiacalix[4]arene containing photochromic mononitrosyl Ru (II) and paramagnetic aqua Gd or Dy complexes

    NASA Astrophysics Data System (ADS)

    Kushch, L. A.; Yagubskii, E. B.; Dmitriev, A. I.; Morgunov, R. B.; Emel'yanov, V. A.; Mustafina, A. R.; Gubaidullin, A. T.; Burilov, V. A.; Solovieva, S. E.; Schaniel, D.; Woike, Th.

    2010-02-01

    Two bifunctional supramolecular systems [RuNO(NH 3) 4OH] 2+·[RuNO(NH 3) 4H 2O] 3+·Gd 3+(H 2O) 6·2[TCAS] 4-·4H 2O (1) and [RuNO(NH 3) 4OH] 2+·[RuNO(NH 3) 4H 2O] 3+·Dy 3+(H 2O) 6·2[TCAS] 4-·4H 2O (2) on the platform of p-sulfonatothiacalix[4]arene containing photochromic mononitrosyl Ru and paramagnetic rare-earth (Gd 3+, Dy 3+) cations have been synthesized. The crystal structures of 1 and 2 are discussed. Their photochromic, magnetic and photomagnetic properties studied by IR and SQUID experimental techniques are presented

  1. Influence of rare earth elements (Y, Gd and Lu) on the luminescent properties of green phosphor ZnMoO4:Tb3+.

    PubMed

    Xu, Y; Yang, W; Li, X; Li, W; Ju, X

    2014-11-01

    (Zn,Lnx )MoO4 :Tb(3+) (Ln = Y(3+), Gd(3+) and Lu(3+) ) were prepared using the co-precipitation method. Phase impurity, morphology and composition were investigated by power X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The experimental results show that crystal structure is not destroyed after doping an appropriate amount of Y(3+), Gd(3+) and Lu(3+). EDS analysis reveals that Y, Gd and Lu have been successfully doped into ZnMoO4 . In addition, the morphology of the phosphors is notably improved, exhibiting homogeneous dispersion morphology and irregular shapes of particle size ~ 0.5-1 µm. The luminescent intensity of (Zn,Lnx )MoO4:Tb(3+) (Ln = Y(3+), Gd(3+) and Lu(3+)) phosphor is obviously higher than that of ZnMoO4 :Tb(3+) phosphor. The energy transfer process between trivalent rare earth ions indicates that the inert earth ions can act as an energy bridge from MoO4(2-) to Tb(3+). PMID:24282116

  2. COEXISTENCE OF SUPERCONDUCTIVITY AND MAGNETIC ORDERING IN THE Y 1? x RE x Ni 2B 2C (RE=Gd, Dy, Ho, Er) SYSTEM

    Microsoft Academic Search

    M. D. Lan; T. J. Chang; C. S. Liaw

    1998-01-01

    The magnetic and superconducting properties of the intermetallic compounds Y1?xRExNi2B2C (RE=Gd, Dy, Ho, Er; 0?x?1.0) have been measured over wide temperature and magnetic field ranges. The existence of the RE3+ paramagnetic ions causes the depression of superconductivity, which can be well interpreted by the Abrikosov–Gor`kov magnetic pair-breaking theory. The corresponding magnetic-ordering temperature increases with increasing magnetic moment concentration while the

  3. The effect of local disorder on the magnetic, electric and thermal properties of RE(Fe1-xAlx)2 (RE=Gd, Dy)

    Microsoft Academic Search

    V. Sima; R. Grossinger; V. Sechovsky; Z. Smetana; H. Sassik

    1984-01-01

    Measurements of magnetic properties, X-ray and neutron diffraction, differential thermal analysis (DTA), thermal expansion and resistivity were made on Gd(Fe1-xAlx)2 and Dy(Fe1-xAlx)2. Both systems exhibit a line broadening observed by X-ray diffraction on the Al-rich side, indicating a small variation of the lattice constants. This effect leads to a smoothing of the magnetic phase transition at the Curie temperature Tc,

  4. Properties of Gd{sub 2}O{sub 3}:Eu{sup 3+}, Tb{sup 3+} nanopowders obtained by sol-gel process

    SciTech Connect

    Ramirez, A. de J. Morales [Instituto Politecnico Nacional, CICATA Unidad Altamira, Km. 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamps (Mexico); Murillo, A. Garcia, E-mail: angarciam@ipn.mx [Instituto Politecnico Nacional, CICATA Unidad Altamira, Km. 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamps (Mexico); Romo, F. de J. Carrillo; Hernandez, M. Garcia [Instituto Politecnico Nacional, CICATA Unidad Altamira, Km. 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamps (Mexico)] [Instituto Politecnico Nacional, CICATA Unidad Altamira, Km. 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamps (Mexico); Vigueras, D. Jaramillo [Instituto Politecnico Nacional, CIITEC, Cerrada CECATI S/N Col. Sta. Catarina, Del. Azcapotzalco, Mexico, D.F. 02250 (Mexico)] [Instituto Politecnico Nacional, CIITEC, Cerrada CECATI S/N Col. Sta. Catarina, Del. Azcapotzalco, Mexico, D.F. 02250 (Mexico); Chaderyron, G.; Boyer, D. [Laboratoire des Materiaux Inorganiques Universite Blaise Pascal CNRS-UMR 6002, 63177 Aubiere (France)] [Laboratoire des Materiaux Inorganiques Universite Blaise Pascal CNRS-UMR 6002, 63177 Aubiere (France)

    2010-01-15

    A significant practical application for nanostructured materials is X-ray medical imagery, because it is necessary to use dense materials in order to enable absorption of high energy photons. An important requirement of these materials is UV-vis range emission produced by X-ray excitation, which can be influenced by the particle size. Europium doped gadolinium oxide is a well known red phosphor. Moreover, nanophosphors of Gd{sub 2}O{sub 3} codoped with Tb{sup 3+}, Eu{sup 3+} increase their light yield by energy transfer between Tb{sup 3+} and Eu{sup 3+}. In this study, Gd{sub 2}O{sub 3} nanopowders codoped with Eu{sup 3+} and Tb{sup 3+} (2.5 at.% Eu{sup 3+}, and 0.005 and 0.01 at.% Tb{sup 3+}) were obtained via a sol-gel process using gadolinium pentanedionate as precursor and europium and terbium nitrates as doping sources. In this paper, we report the influence of annealing temperature on the structure, morphology and luminescent properties of Gd{sub 2}O{sub 3}:Eu{sup 3+}, Tb{sup 3+} by means of TGA, XRD, TEM and X-ray emission measurements.

  5. Syntheses, structure, magnetism, and optical properties of the partially ordered quaternary interlanthanide sulfides PrLnYb{sub 2}S{sub 6} (Ln=Tb, Dy)

    SciTech Connect

    Jin Gengbang [Department of Chemistry and Biochemistry and the E.C. Leach Nuclear Science Center, Auburn University, Auburn, AL 36849 (United States); Choi, Eun Sang [Department of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310 (United States); Guertin, Robert P. [Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States); Brooks, James S. [Department of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310 (United States); Booth, Corwin H. [Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Albrecht-Schmitt, Thomas E. [Department of Chemistry and Biochemistry and the E.C. Leach Nuclear Science Center, Auburn University, Auburn, AL 36849 (United States)], E-mail: albreth@auburn.edu

    2007-09-15

    Dark red single crystals of PrLnYb{sub 2}S{sub 6} (Ln=Pr/Yb, Tb, Dy) have been synthesized through the reactions of elemental rare earth metals and S using a Sb{sub 2}S{sub 3} flux at 1000 deg. C. These isotypic compounds adopt the F-Ln{sub 2}S{sub 3} three-dimensional open-channel structure type. Eight-coordinate Pr{sup 3+} ions sit in the channels that are constructed from three different edge-shared double chains running down the b-axis that contain Yb(1)S{sub 6} octahedra, Yb(2)S{sub 6} octahedra, and LnS{sub 7} monocapped trigonal prisms. Each double chain connects to four other neighbors by sharing vertices and edges. Considerable disordering in Ln positions was observed in single X-ray diffraction experiments only in the case of Pr/Yb. Least-squares refinements gave rise to the formulas of Pr{sub 1.34}Yb{sub 2.66}S{sub 6}, of PrTbYb{sub 2}S{sub 6}, and PrDyYb{sub 2}S{sub 6}, which are confirmed by the elemental analysis and magnetic susceptibility measurements. Pr{sub 1.34}Yb{sub 2.66}S{sub 6}, PrTbYb{sub 2}S{sub 6}, and PrDyYb{sub 2}S{sub 6} are paramagnetic down to 2 K, without any indications of long-range magnetic ordering. The optical transitions for Pr{sub 1.34}Yb{sub 2.66}S{sub 6}, PrTbYb{sub 2}S{sub 6}, and PrDyYb{sub 2}S{sub 6} are at approximately 1.6 eV. Crystallographic data are listed as an example for PrTbYb{sub 2}S{sub 6}: monoclinic, space group P2{sub 1}/m, a=10.9496(10) A, b=3.9429(4) A, c=11.2206(10) A, {beta}=108.525(2){sup o}, V=459.33(7) A{sup 3}, Z=2. - Graphical abstract: An illustration of the three-dimensional structure of PrTbYb{sub 2}S{sub 6} viewed along the b-axis.

  6. Hydrothermal synthesis and luminescent properties of Y{sub 2}O{sub 3}:Tb{sup 3+} and Gd{sub 2}O{sub 3}:Tb{sup 3+} microrods

    SciTech Connect

    Xu Zhenhe, E-mail: xuzh@ciac.jl.cn [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Remin Street, Changchun 130022, and Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Yang Jun; Hou Zhiyao; Li Chunxia; Zhang Cuimiao; Huang Shanshan [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Remin Street, Changchun 130022, and Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Lin Jun, E-mail: jlin@ciac.jl.cn [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Remin Street, Changchun 130022, and Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China)

    2009-09-15

    One-dimensional (1D) Y{sub 2}O{sub 3}:Tb{sup 3+} and Gd{sub 2}O{sub 3}:Tb{sup 3+} microrods have been successfully prepared through a large-scale and facile hydrothermal method followed by a subsequent calcination process in N{sub 2}/H{sub 2} mixed atmosphere. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (IR), thermogravimetric analysis (TGA), energy-dispersive X-ray spectra (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), photoluminescence (PL) and cathodoluminescence (CL) spectra as well as kinetic decays were used to characterize the samples. The as-formed products via the hydrothermal process could transform to cubic Y{sub 2}O{sub 3}:Tb{sup 3+} and Gd{sub 2}O{sub 3}:Tb{sup 3+} with the same morphology and slight shrinking in size after a postannealing process. Both Y{sub 2}O{sub 3}:Tb{sup 3+} and Gd{sub 2}O{sub 3}:Tb{sup 3+} microrods exhibit strong green emission corresponding to {sup 5}D{sub 4} {yields} {sup 7}F{sub 5} transition (542 nm) of Tb{sup 3+} under UV light excitation (307 and 258 nm, respectively), and low-voltage electron beam excitation (1.5 {yields} 3.5 kV), which have potential applications in fluorescent lamps and field emission displays.

  7. Structural transformations and phenomenological description of the formation of phase states in elpasolites Cs2RbDyF6 and Rb2K B'F6 ( B' = Ho, Dy, Tb)

    NASA Astrophysics Data System (ADS)

    Safonov, I. N.; Misyul', S. V.; Molokeev, M. S.; Ivliev, M. P.

    2015-03-01

    The structures of the cubic and monoclinic phases of an Rb2KHoF6 crystal from a series of elpasolites Rb2K B'F6 ( B' = Ho, Dy, Tb), which undergoes a trigger phase transition, have been investigated using X-ray powder diffraction. The critical and noncritical displacements of atoms in the Rb2KHoF6 structure have been determined from the group-theoretical analysis of the complete condensate of order parameters. It has been reliably established that a change in the symmetry due to the phase transition in this crystal can be represented in the form . A phenomenological analysis of the conditions responsible for the formation of phase states upon the phase transitions in elpasolites Cs2RbDyF6 and Rb2K B'F6 ( B' = Ho, Dy, Tb) has been carried out. Taking into account the structural data and using the phenomenological theory, it has been found that the main factor determining the formation of phase states in these and related crystals is the instability of the elpasolite structure with respect to rotational distortions of two types. It has been shown that an important role in the formation of a sequence of structural transformations in these crystals is played by the interaction of rotational order parameters and displacements of the cation from the center of a cuboctahedral hole.

  8. Vacuum ultraviolet spectroscopic properties of rare earth (RE=Ce,Tb,Eu,Tm,Sm)-doped hexagonal KCaGd(PO4)2 phosphate

    NASA Astrophysics Data System (ADS)

    Zhang, Z. J.; Yuan, J. L.; Duan, C. J.; Xiong, D. B.; Chen, H. H.; Zhao, J. T.; Zhang, G. B.; Shi, C. S.

    2007-11-01

    Hexagonal KCaGd(PO4)2:RE3+ (RE =Ce,Tb,Eu,Tm,Sm) were synthesized by coprecipitation method and their vacuum ultraviolet-ultraviolet (VUV-UV) spectroscopic properties were investigated. The bands at about 165nm in the VUV excitation spectra are attributed to the host lattice absorptions. For Ce3+-doped samples, the bands at 207, 256, 275, and 320nm are assigned to the 4f-5d transitions of Ce3+ in KCaGd(PO4)2. For Tb3+-doped sample, the bands at 203 and 222nm are related to the 4f-5d spin-allowed transitions. For Eu3+-doped sample, the O2--Eu3+ charge-transfer band (CTB) at 229nm is observed, and the fine emission spectrum of Eu3+ indicates that Eu3+ ions prefer to occupy Gd3+ or Ca2+ sites in the host lattice. For Tm3+- and Sm3+-doped samples, the O2--Tm3+ and O2--Sm3+ CTBs are observed to be at 176 and 186nm, respectively. From the standpoints of the absorption band, color purity, and luminescent intensity, Tb3+-doped KCaGd(PO4)2 is a potential candidate for 172nm excited green plasma display phosphors.

  9. Decay of {sup 161m1,m2}Dy isomers under conditions of a resonance environment (Moessbauer Screen)

    SciTech Connect

    Loginov, Yu. E., E-mail: yurlo@pnpi.spb.ru; Zinoviev, V. G.; Kabina, L. P.; Lisin, S. S.; Maljutenkov, Ed. I. [Russian Academy of Sciences, Petersburg Nuclear Physics Institute (Russian Federation)

    2013-06-15

    The half-lives of the isomers {sup 161m1}Dy and {sup 161m2}Dy (E = 25.6 keV and T{sub 1/2} {approx} 30 ns for the former and E = 74.6 keV and T{sub 1/2} {approx} 3 ns for the latter) placed in a {sup 160}Gd{sub 2}O{sub 3} crystal lattice at T = 300 K and surrounded by stable {sup 161}Dy nuclei in the composition of {sup 161}Dy{sub 2}O{sub 3} were measured by the method of ({beta}-{gamma}) coincidences in the beta-decay process {sup 161}Tb {yields} {sup 161}Dy. Nuclei of {sup 161m1,m2}Dy were obtained according to the chain {sup 160}Gd(n, {gamma}){sup 161}Gd {yields} {sup 161}Tb {yields} {sup 161}Dy from {sup 160}Dy{sub 2}O{sub 3} weighted portions irradiated at the PWR-M reactor of the Petersburg Nuclear Physics Institute (PNPI, Gatchina, Russia). The T{sub 1/2} value observed for the isomer {sup 161m1}Dy was found to be correlated with the number of surrounding {sup 161}Dy nuclei. The presence of this correlation in {sup 161m1}Dy can be explained by the multiple resonance scattering of photons from isomer decay within the sample used. No such correlation was observed for {sup 161m2}Dy. The half-lives measured for the isomers {sup 161m1}Dy and {sup 161m2}Dy in the absence of the above environment are 29.2(1) and 3.50(1) ns, respectively.

  10. Effects of Co substitution on structural and magnetic properties of R 3(Fe 1? x Co x ) 29? y V y (R=Tb, Dy)

    Microsoft Academic Search

    O. Kalogirou; C. Sarafidis; M. Gjoka; G. Litsardakis

    2002-01-01

    Synthesis of two novel series of intermetallic compounds Tb3(Fe1?xCox)27.4V1.6 (x=0,0.1, 0.2, 0.3, 0.4) and Dy3(Fe1?xCox)27.8V1.2 (x=0, 0.1, 0.2, 0.3) with the monoclinic Nd3(Fe,Ti)29-type structure (3:29) is presented. In the Dy series for x=0.4 a disordered variant of the hexagonal Th2Ni17-type structure is formed. The cell parameters decrease and the Curie temperature increases with increasing of the Co content. In the

  11. Effects of Co substitution on structural and magnetic properties of R3(Fe1-xCox)29- yVy (R=Tb, Dy)

    Microsoft Academic Search

    O. Kalogirou; C. Sarafidis; M. Gjoka; G. Litsardakis

    2002-01-01

    Synthesis of two novel series of intermetallic compounds Tb3(Fe1- xCox)27.4V1.6 (\\/x=0,0.1, 0.2, 0.3, 0.4) and Dy3(Fe1- xCox)27.8V1.2 (\\/x=0, 0.1, 0.2, 0.3) with the monoclinic Nd3(Fe,Ti)29-type structure (3:29) is presented. In the Dy series for \\/x=0.4 a disordered variant of the hexagonal Th2Ni17-type structure is formed. The cell parameters decrease and the Curie temperature increases with increasing of the Co content.

  12. The VUV–vis spectroscopic properties of phosphors Ca 3Gd 2(1? x) Ln 2 x (BO 3) 4 (Ln 3+ = Ce, Sm, Eu, Tb)

    Microsoft Academic Search

    Hongbin Liang; Qiang Su; Ye Tao; Jianhua Xu; Yan Huang

    2006-01-01

    The spectroscopic properties in VUV–vis range for phosphors calcium and gadolinium double borate Ca3Gd2(BO3)4 doped with rare-earth ions Ce3+, Sm3+, Eu3+ and Tb3+ were investigated. The host-related absorption, the f–d transitions of Ce3+ and Tb3+, as well as the charge transfer transitions of Sm3+ and Eu3+ in the host lattice are assigned and discussed. The CIE chromaticity coordinates for Eu3+-

  13. Structural investigation of the new Ca3Ln2Ge3O12 (Ln=Pr, Nd, Sm, Gd and Dy) compounds and luminescence spectroscopy of Ca3Gd2Ge3O12 doped with the Eu3+ ion

    NASA Astrophysics Data System (ADS)

    Piccinelli, F.; Lausi, A.; Bettinelli, M.

    2013-09-01

    The crystal structures of new rare earth-based germanate compounds (Ca3Pr2Ge3O12, Ca3Nd2Ge3O12, Ca3Sm2Ge3O12, Ca3Gd2Ge3O12 and Ca3Dy2Ge3O12) have been determined by Rietveld refinement calculations on the collected synchrotron X-ray diffraction powder patterns. A different distribution of the rare earth ions in the three available crystal sites was observed, as the main structural feature. The reasons of the instability of the silico-carnotite structure for lanthanide ions out of the range Pr-Dy have been proposed. Finally, the luminescence spectroscopy of the Eu3+ dopant ion in Ca3Gd2Ge3O12 was presented and analyzed taking into account the observed structural characteristics. The Eu3+ luminescence spectroscopy was also compared with the one of Eu3+ doped Ca3Gd2Si3O12 and Ca3Lu2Si3O12 isostructural materials.

  14. Performance characteristics of an irreversible regenerative magnetic Brayton refrigeration cycle using Gd0.74Tb0.26 as the working substance

    NASA Astrophysics Data System (ADS)

    Diguet, Gildas; Lin, Guoxing; Chen, Jincan

    2012-10-01

    The cycle model of an irreversible regenerative magnetic Brayton refrigerator using Gd0.74Tb0.26 as the working substance is established. Based on the experimental characteristics of iso-field heat capacities of the material Gd0.74Tb0.26 at 0 T and 2 T, the corresponding iso-field entropies are calculated and the thermodynamic performance of an irreversible regenerative magnetic Brayton refrigeration cycle is investigated. The effects of the irreversibilities in the two adiabatic processes and non-perfect regenerative process of the magnetic Brayton refrigeration cycle on the cooling quantity, the heat quantity released to the hot reservoir, the net cooling quantity and the coefficient of performance are discussed in detail. Some significant results are obtained.

  15. Magnetic ordering in a ternary rare earth-transition metal oxide, R_2RuO_5, R=Pr, Gd and Tb

    Microsoft Academic Search

    R. P. Guertin; S. McCall; C. S. Alexander; Z. X. Zhou; G. Cao; J. E. Crow; C. Mielke

    2001-01-01

    In the insulating rare earth-transition metal oxide series R_2RuO_5, magnetic coupling is associated with both cation species. For R=Gd and Tb, (T_M=10 K and 18 K, respectively), the ordering is likely canted antiferromagnetic. For R=Pr (T_M= 8 K) ordering is spin glass-like, related to the partly structural frustration of the lattice. Field induced magnetic anomalies are observed for T.lt.TM for

  16. Wavelength Dependent Photofragmentation Patterns of Tris(2,2,6,6-tetramethyl-3,5-heptanedionato)Ln (III) (Ln = Eu, Tb, Gd) in a Molecular Beam

    Microsoft Academic Search

    Franklin P. Ow; Mary T. Berry; P. Stanley May; Jeffrey I. Zink

    2006-01-01

    Laser photoionization and ligand photodissociation in Ln(thd) 3 (Ln ) Eu, Tb, Gd; thd ) 2,2,6,6-tetramethyl- 3,5-heptanedionato) are studied in a molecular beam via time-of-flight mass spectrometry. The fragmentation patterns are strongly wavelength dependent. With 355 nm excitation, the mass spectrum is dominated by Ln 2+ ,L n + , and LnO + fragments. The bare Ln ions are believed

  17. Photoluminescence of Ce 3+, Tb 3+, Sm 3+ or Gd 3+ activated Ba 3BP 3O 12 under the VUV and UV excitation

    Microsoft Academic Search

    Cheng-Jun Duan; Wei-Feng Li; Xue-Yan Wu; Hao-Hong Chen; Xin-Xin Yang; Jing-Tai Zhao; Yi-Bing Fu; Ze-Ming Qi; Guo-Bin Zhang; Zhao-Shu Shi

    2005-01-01

    Novel phosphors of Ce3+, Tb3+, Sm3+ or Gd3+ doped Ba3BP3O12 were synthesized by the solid-state reaction method and their VUV–UV spectroscopic properties were investigated. The bands at about 165nm in the VUV excitation spectra are attributed to the host lattice absorptions. The bands at about 216, 238, 269, 282, and 294nm for the sample of Ba3BP3O12: Ce3+ are connected with

  18. The extended chain compounds Ln12(C 2) 3I 17 ( Ln=Pr, Nd, Gd, Dy): Synthesis, structure and physical properties

    NASA Astrophysics Data System (ADS)

    Ryazanov, Mikhail; Mattausch, Hansjürgen; Simon, Arndt

    2007-04-01

    The title compounds are obtained in high yield from stoichiometric mixtures of Ln, LnI 3 and graphite, heated at 900-950 °C in welded Ta containers. The crystal structures of new Pr and Nd phases determined by single-crystal X-ray diffraction are related to those of other Ln12(C 2) 3I 17-type compounds ( C 2/ c, a=19.610(1) and 19.574(4) Å, b=12.406(2) and 12.393(3) Å, c=19.062(5) and 19.003(5) Å, ?=90.45(3)° and 90.41(3)°, for Pr 12(C 2) 3I 17 and Nd 12(C 2) 3I 17, respectively). All compounds contain infinite zigzag chains of C 2-centered metal atom octahedra condensed by edge-sharing into the [tcc] ? sequence (c= cis, t= trans) and surrounded by edge-bridging iodine atoms as well as by apical iodine atoms that bridge between chains. The polycrystalline Gd 12(C 2) 3I 17 sample exhibits semiconducting thermal behavior which is consistent with an ionic formulation ( Ln3+) 12(C 26-) 3(I -) 17(e -) under the assumption that one extra electron is localized in metal-metal bonding. The magnetization measurements on Nd 12(C 2) 3I 17, Gd 12(C 2) 3I 17 and Dy 12(C 2) 3I 17 indicate the coexistence of competing magnetic interactions leading to spin freezing at Tf=5 K for the Gd phase. The Nd and Dy compounds order antiferromagnetically at TN=25 and 29 K, respectively. For Dy 12(C 2) 3I 17, a metamagnetic transition is observed at a critical magnetic field H?25 kOe.

  19. Syntheses, crystal structures and vibrational spectra of KLn(SO{sub 4}){sub 2}.H{sub 2}O (Ln=La, Nd, Sm, Eu, Gd, Dy)

    SciTech Connect

    Kazmierczak, Karolina [Institut fuer Anorganische und Analytische Chemie, Albert-Ludwigs-Universitaet, Albertstrasse 21, D-79104 Freiburg (Germany); Hoeppe, Henning A., E-mail: henning.hoeppe@ac.uni-freiburg.d [Institut fuer Anorganische und Analytische Chemie, Albert-Ludwigs-Universitaet, Albertstrasse 21, D-79104 Freiburg (Germany)

    2010-09-15

    The potassium lanthanide double sulphates KLn(SO{sub 4}){sub 2}.H{sub 2}O (Ln=La, Nd, Sm, Eu, Gd, Dy) were obtained by evaporation of aqueous reaction mixtures of rare earth (III) sulphates and potassium thiocyanate at 298 K. X-ray single-crystal investigations show that KLn(SO{sub 4}){sub 2}.H{sub 2}O (Ln=Nd, Sm, Eu, Gd, Dy) crystallise monoclinically (Ln=Sm: P2{sub 1}/c, Z=4, a=10.047(1), b=8.4555(1), c=10.349(1) A, wR2=0.060, R1=0.024, 945 reflections, 125 parameters) while KLa(SO{sub 4}){sub 2}.H{sub 2}O adopts space group P3{sub 2}21 (Z=3, a=7.1490(5), c=13.2439(12) A, wR2=0.038, R1=0.017, 695 reflections, 65 parameters). The coordination environment of the lanthanide ions in KLn(SO{sub 4}){sub 2}.H{sub 2}O is different in the case of the Nd/Sm/Gd and the Eu/Dy compounds, respectively. In the first case the Ln atoms are nine-fold coordinated in contrast to the latter where the Ln ions are eight-fold coordinated by oxygen atoms. The vibrational spectra of KLn(SO{sub 4}){sub 2}.H{sub 2}O and the UV-vis reflection spectra of KEu(SO{sub 4}){sub 2}.H{sub 2}O and KNd(SO{sub 4}){sub 2}.H{sub 2}O are also reported. - Graphical abstract: The lanthanide potassium double sulphates exhibit an unexpected change in the coordination mode by a simple rotation of sulphate tetrahedron 2.

  20. New Layered Compounds with the General Composition (MO) (CuSe), Where M = Bi, Nd, Gd, Dy, and BiOCuS: Syntheses and Crystal Structure

    NASA Astrophysics Data System (ADS)

    Kusainova, A. M.; Berdonosov, P. S.; Akselrud, L. G.; Kholodkovskaya, L. N.; Dolgikh, V. A.; Popovkin, B. A.

    1994-09-01

    The syntheses of four new copper oxyselenides with the general formula (MO)(CuSe) ( M = Bi, Nd, Gd, Dy) and one copper oxysulfide, BiOCuS, are reported. The tetragonal unit cell dimensions of all compounds are given. A new bismuth-copper oxyselenide, BiOCuSe, has been structurally characterized from powder X-ray diffraction data and finally solved by the Rietveld profile method with RI = 0.069. The BiCuSeO crystal structure is formed by alternating [Bi 2O 2] and [Cu 2Se 2] layers.

  1. Magnetocaloric and magnetotransport properties on R2Ni2Sn compounds (R=Ce, Nd, Sm, Gd, and Tb)

    SciTech Connect

    Kumar, P.; Singh, N.; Suresh, K.; Nigam, A.

    2008-05-12

    We report a detailed magnetic, magnetocaloric, and magnetotransport study on R{sub 2}Ni{sub 2}Sn compounds with different rare earths. The magnetic state of these compounds is found to be complex because of the coexistence of ferromagnetic and antiferromagnetic components. These compounds show phenomena such as multiple magnetic transitions, nonsaturation of magnetization, and metamagnetic transitions. Analysis of the zero-field heat capacity data shows that the magnetic entropy is less than the theoretical value, indicating the presence of some moment on Ni. Schottky anomaly is present in the magnetic heat capacity data of Sm{sub 2}Ni{sub 2}Sn. The temperature variation of magnetocaloric effect reflects the magnetization behavior. Tb{sub 2}Ni{sub 2}Sn and to a less extent Gd{sub 2}Ni{sub 2}Sn show oscillatory magnetocaloric effect. The variation of magnetocaloric effect is correlated with the ferromagnetic-antiferromagnetic phase coexistence. The electrical resistivity analysis has shown that the electron-magnon scattering is prominent at low temperature, while phonon scattering modified by the s-d interaction is crucial at high temperatures. The magnetoresistance is very large in Ce{sub 2}Ni{sub 2}Sn and shows a quadratic dependence on the field, implying the role of spin fluctuations in determining the transport behavior. Large magnetoresistance has been observed in other compounds as well.

  2. Crystal structures of the R 3.33CuPb 1.5Se 7 (R = Tb, Dy, Ho, Er, Tm, Yb and Lu) compounds

    Microsoft Academic Search

    L. D. Gulay; I. D. Olekseyuk

    2005-01-01

    The crystal structures of the R3.33CuPb1.5Se7 (R=Tb, Dy, Ho, Er, Tm, Yb and Lu) compounds (space group Cm, Pearson symbol mC25.67) were determined by means of X-ray powder diffraction: a=1.3624(3)nm, b=0.41144(8)nm, c=1.2645(3)nm, ?=104.68(1)° (for Tb3.33CuPb1.5Se7); a=1.3557(5)nm, b=0.4091(1)nm, c=1.2574(4)nm, ?=104.59(2)° (for Dy3.33CuPb1.5Se7); a=1.35314(8)nm, b=0.40819(2)nm, c=1.25609(7)nm, ?=104.577(3)°, RI=0.0797 (for Ho3.33CuPb1.5Se7); a=1.35018(7)nm, b=0.40693(2)nm, c=1.25433(6)nm, ?=104.492(2)°, RI=0.0845 (for Er3.33CuPb1.5Se7); a=1.34584(7)nm, b=0.40560(2)nm, c=1.25083(6)nm, ?=104.342(3)°, RI=0.0866

  3. Crystal structures of the R 3.33CuPb 1.5S 7 (R = Tb, Dy, Ho, Er and Lu) compounds

    Microsoft Academic Search

    L. D. Gulay; I. D. Olekseyuk

    2006-01-01

    The crystal structures of the R3.33CuPb1.5S7 (R=Tb, Dy, Ho, Er and Lu) compounds (space group Cm, Pearson symbol mC25.67) were determined by means of X-ray powder diffraction: a=1.3129(2)nm, b=0.39791(6)nm, c=1.2176(2)nm, ?=104.96(1)° (Tb3.33CuPb1.5S7); a=1.3079(2)nm, b=0.39591(6)nm, c=1.2119(2)nm, ?=104.996(8)° (Dy3.33CuPb1.5S7); a=1.3047(2)nm, b=0.39462(5)nm, c=1.2090(2)nm, ?=104.885(7)°, RI=0.0982 (Ho3.33CuPb1.5S7); a=1.3011(1)nm, b=0.39313(3)nm, c=1.20606(9)nm, ?=104.884(4)°, RI=0.0834 (Er3.33CuPb1.5S7); a=1.29262(9)nm, b=0.38948(2)nm, c=1.19916(8)nm, ?=104.794(4)°, RI=0.0925 (Lu3.33CuPb1.5S7). The unit cell of R3.33CuPb1.5S7

  4. Synthesis, structure and luminescence studies of Eu(III), Tb(III), Sm(III), Dy(III) cationic complexes with acetylacetone and bis(5-(pyridine-2-yl)-1,2,4-triazol-3-yl)propane?

    PubMed Central

    Gusev, Alexey N.; Hasegawa, Miki; Shimizu, Tomohito; Fukawa, Tomonori; Sakurai, Shoya; Nishchymenko, Galyna A.; Shul’gin, Victor F.; Meshkova, Svetlana B.; Linert, Wolfgang

    2013-01-01

    Studies concerning synthesis, structure and luminescence of eight-coordinate Eu, Tb, Sm and Dy complexes of the type [Ln(acac)2(L)]Cl (Hacac = pentanedione-2,4 and L = bis(5-(pyridine-2-yl)-1,2,4-triazol-3-yl)propane) are reported in detail. The obtained complexes were investigated by various means including elemental- and thermogravimetric analysis, IR- and electron transition spectroscopy. The structure of the Tb complex was determined by single-crystal X-ray crystallography: Tb is eight-coordinate, and L acting only as a tetradentate chelate together with two bidentate acac ligands. Photophysical studies of the complexes were carried out. The Tb(III) and Eu(III) complexes show strong emissions both in solid state and solution. The intensity of the luminescence of Dy(III) and Sm(III) are relatively weak. The factors determining the intensity of the photoluminescence are discussed. PMID:24068839

  5. Synthesis, structure and luminescence studies of Eu(III), Tb(III), Sm(III), Dy(III) cationic complexes with acetylacetone and bis(5-(pyridine-2-yl)-1,2,4-triazol-3-yl)propane.

    PubMed

    Gusev, Alexey N; Hasegawa, Miki; Shimizu, Tomohito; Fukawa, Tomonori; Sakurai, Shoya; Nishchymenko, Galyna A; Shul'gin, Victor F; Meshkova, Svetlana B; Linert, Wolfgang

    2013-09-01

    Studies concerning synthesis, structure and luminescence of eight-coordinate Eu, Tb, Sm and Dy complexes of the type [Ln(acac)2(L)]Cl (Hacac = pentanedione-2,4 and L = bis(5-(pyridine-2-yl)-1,2,4-triazol-3-yl)propane) are reported in detail. The obtained complexes were investigated by various means including elemental- and thermogravimetric analysis, IR- and electron transition spectroscopy. The structure of the Tb complex was determined by single-crystal X-ray crystallography: Tb is eight-coordinate, and L acting only as a tetradentate chelate together with two bidentate acac ligands. Photophysical studies of the complexes were carried out. The Tb(III) and Eu(III) complexes show strong emissions both in solid state and solution. The intensity of the luminescence of Dy(III) and Sm(III) are relatively weak. The factors determining the intensity of the photoluminescence are discussed. PMID:24068839

  6. Syntheses, Structure, Magnetism, and Optical Properties of the Partial Ordered Quaternary Interlanthanide Sulfides PrLnYb2S6 (Ln = Tb, Dy)

    SciTech Connect

    Booth, Corwin H; Jin, Geng Bang; Choi, Eun Sang; Guertin, Robert P.; Brooks, James S.; Bray, Travis H.; Booth, Corwin H.; Albrecht-Schmitt, Thomas E.

    2008-01-11

    Dark red single crystals of PrLnYb{sub 2}S{sub 6} (Ln = Pr/Yb, Tb, Dy) have been synthesized through the reaction of elemental rare earth metals and S using a Sb{sub 2}S{sub 3} flux at 1000 C. These isotypic compounds adopt the F-Ln{sub 2}S3 three-dimensional open channel structure type. Eight-coordinate Pr{sup 3+} ions sit in the channels, which are constructed from three different edge-shared double chains running down the b axis, which contain Yb(1)S{sub 6} octahedra, Yb(2)S{sub 6}, octahedra and LnS{sub 7} monocapped trigonal prisms, respectively. Each double chain connects to four other neighbors by sharing vertices and edges. Considerable disordering in Ln positions was observed in single X-ray diffraction experiments only in the case of Pr/Yb. Least square refinements gave rise to the formulas of Pr{sub 1.34}Yb{sub 2.66}S{sub 6}, of PrTbYb{sub 2}S{sub 6}, and PrDyYb{sub 2}S{sub 6}, which are confirmed by the elemental analysis and magnetic susceptibility measurements. Pr1.34Yb2.66S{sub 6}, PrTbYb{sub 2}S{sub 6} and PrDyYb{sub 2}S{sub 6} are paramagnetic down to 2 K without any indications of long range magnetic ordering. The optical transitions for Pr{sub 1.34}Yb{sub 2.66}S{sub 6}, PrTbYb{sub 2}S{sub 6}, and PrDyYb{sub 2}S{sub 6} are at approximately 1.6 eV. Crystallographic data: Pr{sub 1.34}Yb{sub 2.66}S{sub 6}, monoclinic, space group P2{sub 1}/m, a = 10.960(2), b = 3.9501(8), c = 11.220(2) {angstrom}, {beta} = 108.545(3), V = 460.54(16), Z = 2; PrTbYb{sub 2}S{sub 6}, monoclinic, space group P2{sub 1}/m, a = 10.9496(10), b = 3.9429(4), c = 11.2206(10) {angstrom}, {beta} = 108.525(2), V = 459.33(7), Z = 2; PrDyYb{sub 2}S{sub 6}, monoclinic, space group P2{sub 1}/m, a = 10.9384(10), b = 3.9398(4), c = 11.2037(10) {angstrom}, {beta} = 108.612(2), V = 457.57(7), Z = 2.

  7. Influence of Gd{sup 3+} on the visible quantum cutting in green-emitting silicate Na{sub 3}Gd{sub 0.9?x}Y{sub x}Si{sub 3}O{sub 9}:0.1Tb{sup 3+} phosphors

    SciTech Connect

    Han, Lili [Department of Material Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Wang, Yuhua, E-mail: wyh@lzu.edu.cn [Department of Material Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Zhao, Lei; Zhang, Jia; Wang, Yanzhao [Department of Material Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Tao, Ye [Laboratory of Beijing Synchrotron Radiation, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

    2013-06-01

    Highlights: ? The visible quantum cutting between Tb{sup 3+} in silicate Na{sub 3}Gd{sub 0.9?x}Y{sub x}Si{sub 3}O{sub 9}:0.1Tb{sup 3+} phosphors are firstly investigated. ? Gd{sup 3+} plays an important intermediate role during the QC process and reinforces the cross relaxation efficiency. ? Na{sub 3}Gd{sub 0.9}Tb{sub 0.1}Si{sub 3}O{sub 9} has potential application for 3D-PDPs and Hg-free lamps for the total QE of 151.2%. - Abstract: The visible quantum cutting via cross-relaxation between Tb{sup 3+} ions in Na{sub 3}Gd{sub 0.9?x}Y{sub x}Si{sub 3}O{sub 9}:0.1Tb{sup 3+} phosphors are identified for the first time. It has also been found that with the increase of the ratio of Gd{sup 3+}/Y{sup 3+}, the quantum cutting efficiency increases, which indicates the Gd{sup 3+} plays an important intermediate role in energy transfer to convert vacuum ultraviolet light to visible light and reinforces the cross relaxation efficiency during the quantum cutting process. In addition, the energy transfer process from Gd{sup 3+} to Tb{sup 3+} is also investigated and discussed in terms of luminescence spectra.

  8. Single-component and warm-white-emitting phosphor NaGd(WO4)2:Tm3+, Dy3+, Eu3+: synthesis, luminescence, energy transfer, and tunable color.

    PubMed

    Liu, Yan; Liu, Guixia; Wang, Jinxian; Dong, Xiangting; Yu, Wensheng

    2014-11-01

    Tm(3+), Dy(3+), and Eu(3+) codoped NaGd(WO4)2 phosphors were prepared by a facile hydrothermal process; they were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectrometer (EDS), photoluminescence spectra, and fluorescence lifetime. The results show that the novel octahedral microcrystals with a mean side length of 2 ?m are obtained. Under the excitation of ultraviolet, individual RE(3+) ion (Tm(3+), Dy(3+), and Eu(3+)) activated NaGd(WO4)2 phosphors exhibit excellent emission properties in their respective regions. Moreover, when codoping Dy(3+) and Eu(3+)/Tm(3+) in the single component, the energy migration from Dy(3+) to Eu(3+) has been demonstrated to be a resonant type via a dipole-quadrupole mechanism as well as that from Tm(3+) to Dy(3+) ions, of which the critical distance (R(Dy-Eu)) is calculated to be 11.08 Å. More significantly, in the Tm(3+), Dy(3+), and Eu(3+) tridoped NaGd(WO4)2 phosphors, the energy migration of Tm(3+)-Dy(3+)-Eu(3+), utilized for sensitizing Eu(3+) ions besides compensating the red component at low Eu(3+) doping concentration, has been discussed first. In addition, under 365 nm near-ultraviolet radiation (nUV), the color-tunable emissions in octahedral NaGd(WO4)2 microcrystals are realized by giving abundant blue, green, white, yellow, and red emissions, especially warm white emission, and could be favorable candidates in full-color phosphors for nUV-LEDs. PMID:25303406

  9. Photoluminescence properties of rare earths (Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+} and Tm{sup 3+}) activated NaInW{sub 2}O{sub 8} wolframite host lattice

    SciTech Connect

    Asiri Naidu, S.; Boudin, S. [Laboratoire de Cristallographie et Sciences des Materiaux, ENSICAEN, Universite de Caen, CNRS, 6 Bd Marechal Juin, F-14050 Caen (France); Varadaraju, U.V. [Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036 (India); Raveau, B., E-mail: bernard.raveau@ensicaen.fr [Laboratoire de Cristallographie et Sciences des Materiaux, ENSICAEN, Universite de Caen, CNRS, 6 Bd Marechal Juin, F-14050 Caen (France)

    2012-01-15

    The photoluminescence (PL) studies on NaIn{sub 1-x}RE{sub x}W{sub 2}O{sub 8}, with RE=Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+} and Tm{sup 3+} phases have shown that the relative contribution of the host lattice and of the intra-f-f emission of the activators to the PL varies with the nature of the rare earth cation. In the case of Dy{sup 3+} and Tm{sup 3+} activators, with yellow and blue emission, respectively, the energy transfer from host to the activator plays a major role. In contrast for Eu{sup 3+}, with intense red emission, the host absorption is less pronounced and the intra-f-f transitions of the Eu{sup 3+} ions play a major role, whereas for Tb{sup 3+} intra-f-f transitions are only observed, giving rise to green emission. - Graphical abstract: NaInW{sub 2}O{sub 8} double tungstate doped with Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+}and Tm{sup 3+} shows characteristic emission of intense red for Eu{sup 3+}, yellow for Dy{sup 3+}, green for Tb{sup 3+} and blue for Tm{sup 3+}. Highlights: Black-Right-Pointing-Pointer Characteristic emissions of rare earths (Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+} and Tm{sup 3+}) are observed NaInW{sub 2}O{sub 8} wolframite. Black-Right-Pointing-Pointer Energy transfer from host to the activators (Eu{sup 3+} Dy{sup 3+} Tm{sup 3+} is observed. Black-Right-Pointing-Pointer PL properties of rare earth ions depend on minor structural variations in the host lattice.

  10. Vacuum ultraviolet spectroscopic properties of rare earth (RE=Ce,Tb,Eu,Tm,Sm)-doped hexagonal KCaGd(PO{sub 4}){sub 2} phosphate

    SciTech Connect

    Zhang, Z. J.; Yuan, J. L.; Duan, C. J.; Xiong, D. B.; Chen, H. H.; Zhao, J. T.; Zhang, G. B.; Shi, C. S. [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China) and Graduate School of Chinese Academy of Science, Beijing 100039 (China); National Synchrotron Radiation Laboratory, University of Science and Technology of China, Heifei 230026 (China)

    2007-11-01

    Hexagonal KCaGd(PO{sub 4}){sub 2}:RE{sup 3+} (RE=Ce,Tb,Eu,Tm,Sm) were synthesized by coprecipitation method and their vacuum ultraviolet-ultraviolet (VUV-UV) spectroscopic properties were investigated. The bands at about 165 nm in the VUV excitation spectra are attributed to the host lattice absorptions. For Ce{sup 3+}-doped samples, the bands at 207, 256, 275, and 320 nm are assigned to the 4f-5d transitions of Ce{sup 3+} in KCaGd(PO{sub 4}){sub 2}. For Tb{sup 3+}-doped sample, the bands at 203 and 222 nm are related to the 4f-5d spin-allowed transitions. For Eu{sup 3+}-doped sample, the O{sup 2-}-Eu{sup 3+} charge-transfer band (CTB) at 229 nm is observed, and the fine emission spectrum of Eu{sup 3+} indicates that Eu{sup 3+} ions prefer to occupy Gd{sup 3+} or Ca{sup 2+} sites in the host lattice. For Tm{sup 3+}- and Sm{sup 3+}-doped samples, the O{sup 2-}-Tm{sup 3+} and O{sup 2-}-Sm{sup 3+} CTBs are observed to be at 176 and 186 nm, respectively. From the standpoints of the absorption band, color purity, and luminescent intensity, Tb{sup 3+}-doped KCaGd(PO{sub 4}){sub 2} is a potential candidate for 172 nm excited green plasma display phosphors.

  11. Tunable-color luminescence via energy transfer in NaCa13/18Mg5/18PO4:A (A = Eu2+/Tb3+/Mn2+, Dy3+) phosphors for solid state lighting.

    PubMed

    Li, Kai; Fan, Jian; Mi, Xiaoyun; Zhang, Yang; Lian, Hongzhou; Shang, Mengmeng; Lin, Jun

    2014-11-17

    A series of NaCa13/18Mg5/18PO4(NCMPO):A (A = Eu(2+)/Tb(3+)/Mn(2+), Dy(3+)) phosphors have been prepared by the high-temperature solid-state reaction method. The X-ray diffraction (XRD) and Rietveld refinement, X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), cathodoluminescence (CL), decay lifetimes, and PL quantum yields (QYs) were utilized to characterize the phosphors. The pure crystalline phase of as-prepared samples has been demonstrated via XRD measurement and Rietveld refinements. XPS reveals that the Eu(2+)/Tb(3+)/Mn(2+) can be efficiently doped into the crystal lattice. NCMPO:Eu(2+)/Tb(3+)/Mn(2+) phosphors can be effectively excited under UV radiation, which show tunable color from purple-blue to red including white emission based on energy transfer from Eu(2+) to Tb(3+)/Mn(2+) ions. Under low-voltage electron beam bombardment, the NCMPO:A (A = Eu(2+)/Tb(3+)/Mn(2+), Dy(3+)) display their, respectively, characteristic emissions with different colors, and the CL spectrum of NCMPO:0.04Tb(3+) has the comparable intensity to the ZnO:Zn commercial product. In addition, the calculated CIE coordinate of NCMPO:0.04Tb(3+) (0.252, 0.432) is more saturated than it (0.195, 0.417). These results reveal that NCMPO:A (A = Eu(2+)/Tb(3+)/Mn(2+), Dy(3+)) may be potential candidate phosphors for WLEDs and FEDs. PMID:25375961

  12. Dy-Mn-Si as a representative of family of ‘Dy-Transition Metal-Si’ systems: Its isothermal sections, empirical rProd. Type: FTPules and new rare-earth manganese silicides

    NASA Astrophysics Data System (ADS)

    Morozkin, A. V.; Knotko, A. V.; Yapaskurt, V. O.; Provino, A.; Manfrinetti, P.; Yao, Jinlei; Yuan, Fang; Mozharivskyj, Y.

    2013-10-01

    X-ray and microprobe analyses were employed for the investigation of Dy-Mn-Si system at 870/1070/1170 K. The Dy-Mn-Si system, contains the known DyMn2Si2, DyMnSi and Dy2Mn3Si5 compounds and DyMn4Si2, Dy2MnSi2 and Dy3Mn2Si3 were new compounds identified first time and their structure are of the type TmCu4Sb2, Sc2CoSi2 and Hf3Ni2Si3 respectively. The quasi-binary solid solutions were detected at 870/1070/1170 K: the ThMn12-type Dy8Mn87Si5, Th6Mn23-type Dy23Mn72Si5, MgCu2-type Dy33Mn58Si9 and AlB2-type Dy38Mn2Si58. The other binary compounds of the Dy-Mn-Si system do not show any visible solubility. New phases R2MnSi2 and R3Mn2Si3 (R=Gd, Tb, Ho-Tm) were found out and their structure of the type Sc2CoSi2 and Hf3Ni2Si3 respectively. The specific features of ‘Dy-Transition Metal-Si’ systems were discussed. The ternary solid solution based on the binary compounds of the Dy-Mn and Dy-Si systems: the ThMn12-type Dy8Mn87Si5, Th6Mn23-type Dy23Mn72Si5, MgCu2-type Dy33Mn58Si9 and AlB2-type Dy38Mn2Si58. The other binary compounds of the Dy-Mn-Si system do not show any visible solubility. New Sc2CoSi2-type R2MnSi2 and Hf3Ni2Si3-type R3Mn2Si3 phases were discovered for R=Gd, Tb, Ho-Tm.

  13. Burst magnetostriction in Tb{sub 0.3}Dy{sub 0.7}Fe{sub 1.9}

    SciTech Connect

    Armstrong, W.D. [Riso/ National Laboratory, Materials Department, DK-4000 Roskilde (Denmark)] [Riso/ National Laboratory, Materials Department, DK-4000 Roskilde (Denmark)

    1997-04-01

    The magnetostriction and magnetic induction calculated by a continuous, anisotropic, anhysteric, magnetization model are compared with magnetostriction and magnetic induction measurements on burst and nonburst magnetostrictive Tb{sub 0.3}Dy{sub 0.7}Fe{sub 1.9} twinned single crystal rods. The model shows that the magnetostriction and permeability suppression occurring at low applied field is the result of the rotation, and subsequent capture, of initial field antiparallel magnetization into field transverse [11{bar 1}] or [{bar 1}{bar 1}1] local magnetoelastic energy minima. The model further shows that the interval of high magnetostriction applied field derivative, d{lambda}/dH is the result of the rotation of field transverse [11{bar 1}] or [{bar 1}{bar 1}1] oriented magnetization into the [111] near field magnetocrystalline minima. The occurance of burst magnetostriction is therefore contingent on obtaining sufficient magnetocrystalline anisotropy and sufficiently tight magnetization energy distribution in experimental Tb{sub 0.3}Dy{sub 0.7}Fe{sub 1.9} twinned single crystal rods so as to minimize the applied field interval over which this magnetization rotation process occurs. The present model is able to correctly approximate the applied field dependence of the burst magnetostriction response and the applied field dependence of the simultaneous magnetostriction and permeability suppression with a single set of parameters for a range of constant [112] applied compressive stresses, and correct saturation magnetostrictions for a range of experimentally applied compressive stresses. However, the model fails to match the experimental behavior above a simultaneous d{lambda}/dH, permeability and field hysteresis transition, located approximately 1000 microstrain from the saturation magnetostriction. The experimental transition clearly indicates a change in magnetization mechanism not accommodated by the present model. (Abstract Truncated)

  14. The extended chain compounds Ln {sub 12}(C{sub 2}){sub 3}I{sub 17} (Ln=Pr, Nd, Gd, Dy): Synthesis, structure and physical properties

    SciTech Connect

    Ryazanov, Mikhail [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstr. 1, D-70569 Stuttgart (Germany); Mattausch, Hansjuergen [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstr. 1, D-70569 Stuttgart (Germany); Simon, Arndt [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstr. 1, D-70569 Stuttgart (Germany)], E-mail: A.Simon@fkf.mpg.de

    2007-04-15

    The title compounds are obtained in high yield from stoichiometric mixtures of Ln, LnI{sub 3} and graphite, heated at 900-950 deg. C in welded Ta containers. The crystal structures of new Pr and Nd phases determined by single-crystal X-ray diffraction are related to those of other Ln {sub 12}(C{sub 2}){sub 3}I{sub 17}-type compounds (C 2/c, a=19.610(1) and 19.574(4) A, b=12.406(2) and 12.393(3) A, c=19.062(5) and 19.003(5) A, {beta}=90.45(3){sup o} and 90.41(3){sup o}, for Pr{sub 12}(C{sub 2}){sub 3}I{sub 17} and Nd{sub 12}(C{sub 2}){sub 3}I{sub 17}, respectively). All compounds contain infinite zigzag chains of C{sub 2}-centered metal atom octahedra condensed by edge-sharing into the [tcc] {sub {infinity}} sequence (c=cis, t=trans) and surrounded by edge-bridging iodine atoms as well as by apical iodine atoms that bridge between chains. The polycrystalline Gd{sub 12}(C{sub 2}){sub 3}I{sub 17} sample exhibits semiconducting thermal behavior which is consistent with an ionic formulation (Ln {sup 3+}){sub 12}(C{sub 2} {sup 6-}){sub 3}(I{sup -}){sub 17}(e{sup -}) under the assumption that one extra electron is localized in metal-metal bonding. The magnetization measurements on Nd{sub 12}(C{sub 2}){sub 3}I{sub 17}, Gd{sub 12}(C{sub 2}){sub 3}I{sub 17} and Dy{sub 12}(C{sub 2}){sub 3}I{sub 17} indicate the coexistence of competing magnetic interactions leading to spin freezing at T {sub f}=5 K for the Gd phase. The Nd and Dy compounds order antiferromagnetically at T {sub N}=25 and 29 K, respectively. For Dy{sub 12}(C{sub 2}){sub 3}I{sub 17}, a metamagnetic transition is observed at a critical magnetic field H{approx}25 kOe. - Graphical abstract: Zigzag chains of edge-sharing metal atom octahedra in Ln {sub 12}(C{sub 2}){sub 3}I{sub 17}.

  15. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Hydrothermal Synthesis and Vacuum Ultraviolet-Excited Luminescence Properties of Novel Dy3+-doped GdPO4 White Light Phosphors

    NASA Astrophysics Data System (ADS)

    Han, Guo-Cai; Wang, Yu-Hua; Wu, Chun-Fang; Zhang, Jia-Chi; Lu, Yang-Hua

    2009-06-01

    Novel Dy3+-doped GdPO4 white light phosphors with a monoclinic system are successfully synthesized by the hydrothermal method at 240°C. The strong absorption at around 147 nm in the excitation spectrum is assigned to the host absorption. It is suggested that the vacuum ultraviolet excited energy is transferred from the host to the Dy3+ ions. The f - d transition of the Dy3+ ion is observed to be located at 182 nm, which is consistent with the calculated value using Dorenbos's expression. Under 147nm excitation, Gd0.92PO4:0.08Dy3+ phosphor exhibits two emission bands located at 572 nm (yellow) and 478 nm (blue), which correspond to the hypersensitive transitions 4F9/2-6H13/2 and 4F9/2-6H15/2. The two emission bands lead to the white light. Because of the strong absorption at about 147nm, Gd0.92PO4:0.08Dy3+ under vacuum ultraviolet excitation is an effective white light phosphor, and has promising applications to mercury-free lamps.

  16. Single-particle and collective mode couplings associated with 1- and 2-directional electronic ordering in metallic RTe3 (R = Ho, Dy, Tb)

    SciTech Connect

    Yusupov, R.V.; Mertelj, T.; /Stefan Inst., Ljubljana; Chu, J.-H.; Fisher, I.R.; /Stanford U., Geballe Lab.; Mihailovic, D.; /Stefan Inst., Ljubljana

    2010-02-15

    The coupling of phonons with collective modes and single-particle gap excitations associated with one (1d) and two-directional (2d) electronically-driven charge-density wave (CDW) ordering in metallic RTe{sub 3} is investigated as a function of rare-earth ion chemical pressure (R = Tb, Dy, Ho) using femtosecond pump-probe spectroscopy. From the T-dependence of the CDW gap {Delta}{sub CDW} and the amplitude mode (AM) we find that while the transition to a 1d-CDW ordered state at Tc1 initially proceeds in an exemplary mean-field (MF)-like fashion, below T{sub c1}, {Delta}{sub CDW} is depressed and departs from the MF behavior. The effect is apparently triggered by resonant mode-mixing of the amplitude mode (AM) with a totally symmetric phonon at 1.75 THz. At low temperatures, when the state evolves into a 2d-CDW ordered state at T{sub c2} in the DyTe{sub 3} and HoTe{sub 3}, additional much weaker mode mixing is evident but no soft mode is observed.

  17. Terbium-doped gadolinium oxysulfide (Gd2O2S:Tb) scintillation-based polymer optical fibre sensor for real time monitoring of radiation dose in oncology

    NASA Astrophysics Data System (ADS)

    Lewis, E.; O'Keeffe, S.; Grattan, M.; Hounsell, A.; McCarthy, D.; Woulfe, P.; Cronin, J.; Mihai, L.; Sporea, D.; Santhanam, A.; Agazaryan, N.

    2014-05-01

    A PMMA based plastic optical fibre sensor for use in real time radiotherapy dosimetry is presented. The optical fibre tip is coated with a scintillation material, terbium-doped gadolinium oxysulfide (Gd2O2S:Tb), which fluoresces when exposed to ionising radiation (X-Ray). The emitted visible light signal penetrates the sensor optical fibre and propagates along the transmitting fibre at the end of which it is remotely monitored using a fluorescence spectrometer. The results demonstrate good repeatability, with a maximum percentage error of 0.5% and the response is independent of dose rate.

  18. Cyclo- and carbophosphazene-supported ligands for the assembly of heterometallic (Cu2+/Ca2+, Cu2+/Dy3+, Cu2+/Tb3+) complexes: synthesis, structure, and magnetism.

    PubMed

    Chandrasekhar, Vadapalli; Senapati, Tapas; Dey, Atanu; Das, Sourav; Kalisz, Marguerite; Clérac, Rodolphe

    2012-02-20

    The carbophosphazene and cyclophosphazene hydrazides, [{NC(N(CH(3))(2))}(2){NP{N(CH(3))NH(2)}(2)}] (1) and [N(3)P(3)(O(2)C(12)H(8))(2){N(CH(3))NH(2)}(2)] were condensed with o-vanillin to afford the multisite coordination ligands [{NC(N(CH(3))(2))}(2){NP{N(CH(3))N?CH-C(6)H(3)-(o-OH)(m-OCH(3))}(2)}] (2) and [{N(2)P(2)(O(2)C(12)H(8))(2)}{NP{N(CH(3))N?CH-C (6)H(3)-(o-OH)(m-OCH(3))}(2)}] (3), respectively. These ligands were used for the preparation of heterometallic complexes [{NC(N(CH(3))(2))}(2){NP{N(CH(3))N?CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{CuCa(NO(3))(2)}] (4), [{NC(N(CH(3))(2))}(2){NP{N(CH(3))N?CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{Cu(2)Ca(2)(NO(3))(4)}]·4H(2)O (5), [{NC(N(CH(3))(2))}(2){NP{N(CH(3))N?CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{CuDy(NO(3))(4)}]·CH(3)COCH(3) (6), [{NP(O(2)C(12)H(8))}(2){NP{N(CH(3))N?CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{CuDy(NO(3))(3)}] (7), and [{NP(O(2)C(12)H(8))}(2){NP{N(CH(3))N?CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{CuTb(NO(3))(3)}] (8). The molecular structures of these compounds reveals that the ligands 2 and 3 possess dual coordination pockets which are used to specifically bind the transition metal ion and the alkaline earth/lanthanide metal ion; the Cu(2+)/Ca(2+), Cu(2+)/Tb(3+), and Cu(2+)/Dy(3+) pairs in these compounds are brought together by phenoxide and methoxy oxygen atoms. While 4, 6, 7, and 8 are dinuclear complexes, 5 is a tetranuclear complex. Detailed magnetic properties on 6-8 reveal that these compounds show weak couplings between the magnetic centers and magnetic anisotropy. However, the ac susceptibility experiments did not reveal any out of phase signal suggesting that in these compounds slow relaxation of magnetization is absent above 1.8 K. PMID:22320309

  19. Magnetic characteristics of RCo13 xSix alloys (R La, Pr, Nd, Gd, and Dy) M. Q. Huang and W. E. Wallace

    E-print Network

    McHenry, Michael E.

    .470 730.43 4.0 bct 7.805 11.539 1.478 702.93 4.5 bct Co2Si 7.826 11.566 1.478 708.37 Nd 3.0 bct fcc, 1:11c.5 bct Co2Si 7.797 11.552 1.481 702.28 Gd 3.5 bct 1:11 4.0 bct fcc, Co2Si 7.773 11.495 1.478 694.52 Dy 3.5 bct 1:11 4.0 bct Co2Si 7.758 11.491 1.481 691.66 a fcc signifies the NaZn13 structure.

  20. Synthesis and characterization of ultrafine Ln{sub 2}Ti{sub 2}O{sub 7} (Ln = Sm, Gd, Dy, Er) pyrochlore oxides by stearic acid method

    SciTech Connect

    Zhang Weiguang, E-mail: zhangweiguang68@yahoo.com.cn [Jiangsu Key Laboratory for Chemistry of Low-Dimensional Materials, Huaiyin Normal University, Jiangsu Province, 223300 (China); Zhang Lili; Zhong Hui [Jiangsu Key Laboratory for Chemistry of Low-Dimensional Materials, Huaiyin Normal University, Jiangsu Province, 223300 (China); Lu Lude; Yang Xujie [Materials Chemistry Laboratory, Nanjing University of Science and Technology, Nanjing 210094 (China); Wang Xin, E-mail: wangx@mail.njust.edu.cn [Materials Chemistry Laboratory, Nanjing University of Science and Technology, Nanjing 210094 (China)

    2010-02-15

    Stearic acid method (SAM) was developed to synthesize series of pyrochlore Ln{sub 2}Ti{sub 2}O{sub 7} (Ln = Sm, Gd, Dy, Er) nanocrystals. The synthesis process was monitored by X-ray diffraction, Thermal-gravimetric-differential thermal analysis and Fourier Transform InfraRed methods. Comparing with traditional solid-state reaction (SSR), Ln{sub 2}Ti{sub 2}O{sub 7} can be synthesized at relatively low temperature (700-800 deg. C) with shortened reaction time (2-4 h). The average particle size of Ln{sub 2}Ti{sub 2}O{sub 7} was greatly reduced (ca. 40 nm) and the BET surface area was increased (ca. 12 m{sup 2}/g) by using SAM. From the X-ray diffraction patterns, we found that Ln has an effect on the crystal structure of Ln{sub 2}Ti{sub 2}O{sub 7}, every lattice peak shifted to larger angle slightly with the increasing atomic number of Ln. Also, the lattice constant of Ln{sub 2}Ti{sub 2}O{sub 7} was calculated by Jade.5 and found it decreased along with the decrease of ionic radius of Ln{sup 3+}. The morphology of obtained Ln{sub 2}Ti{sub 2}O{sub 7} was determined by transmission electron microscopy technique. Results showed that the obtained Ln{sub 2}Ti{sub 2}O{sub 7} were all square-like and the interplanar distance of Ln{sub 2}Ti{sub 2}O{sub 7} (Ln = Sm, Gd, Dy, Er) according to (111) plane was 0.65, 0.64, 0.63, and 0.62 nm respectively, which was measured from High Resolution Transmission Electron Microscopy images. Possible reason for this phenomenon was presented.

  1. Emissions and photocatalytic selectivity of SrWO4:Ln3+ (Eu3+, Tb3+, Sm3+ and Dy3+) prepared by a supersonic microwave co-assistance method.

    PubMed

    Zheng, Yuhui; Lin, Jintai; Wang, Qianming

    2012-10-01

    The chemical effects of high intensity ultrasound and microwave irradiation on lanthanide (Eu(3+), Tb(3+), Sm(3+) and Dy(3+)) activated SrWO(4) phosphors were extensively studied. Four classes of characteristic optically active materials (red, green, orange-red and blue-yellow) with striking luminescence were facilely prepared under very low temperature (70 °C) in 45 min. Particularly, Sm(3+), Dy(3+) and Eu(3+) doped strontium tungstates were visible-light driven emissive. The photocatalytic properties of these luminescent lanthanide doped tungstates were systematically examined by investigating the degradation behavior of different dyes. PMID:22854656

  2. A novel tunable blue-green-emitting CaGdGaAl2O7:Ce(3+),Tb(3+) phosphor via energy transfer for UV-excited white LEDs.

    PubMed

    Liang, Chao; You, Hongpeng; Fu, Yibing; Teng, Xiaoming; Liu, Kai; He, Jinhua

    2015-05-01

    CaGdGaAl2O7 and CaGdGaAl2O7:Ce(3+),Tb(3+) have been synthesized by a traditional solid state reaction for the first time. The Rietveld refinement confirmed that CaGdGaAl2O7 has a tetragonal crystal system with the space group P4[combining macron]21m. The photoluminescence properties show that the obtained phosphors can be efficiently excited in the range from 330 to 400 nm, which matches perfectly with commercial UV LED chips. A tunable blue-green emitting CaGdGaAl2O7:Ce(3+),Tb(3+) phosphor has been obtained, by codoping Ce(3+) and Tb(3+) ions into the host and varying their relative ratios, and may be a good candidate for blue-green components in UV white LEDs. The luminescence properties and lifetimes reveal an efficient energy transfer from the Ce(3+) to Tb(3+) ions. The energy transfer is demonstrated to be a dipole-quadrupole mechanism, and the critical distance for Ce(3+) to Tb(3+) calculated by the concentration quenching is 12.25 Å. PMID:25833815

  3. Structural, dielectric and magnetic properties of Gd and Dy doped (Bi0.95RE0.05)(Fe0.95Mn0.05)O3 ceramics synthesized by SSR method

    NASA Astrophysics Data System (ADS)

    Thakur, Shweta; Rai, Radheshyam; Tiwari, Ashutosh

    2014-11-01

    The multiferroic (Bi0.95RE0.05)(Fe0.95Mn0.05)O3 (where RE is Gd (BGFM) and Dy (BDFM)) has been synthesized by using the solid state reaction (SSR) technique. Effects of Gd and Dy substitutions on the structure, electrical and ferroelectric properties of (Bi0.95RE0.05)(Fe0.95Mn0.05)O3 samples have been studied by performing X-ray diffraction, dielectric measurements and magnetic measurements. The crystal structure of the ceramic samples shows a monoclinic phase. Studies of dielectric properties (dielectric constant (?) and tangent loss (tan ?)) both as a function of frequency (10 and 100 kHz) and temperatures (20-300 °C) exhibit dielectric anomaly in the range of (225-245 °C) suggesting a possible ferroelectric-paraelectric phase transition in the compounds. The vibrating sample magnetometer (VSM) measurement shows a significant change in the magnetic properties of Gd and Dy doped (Bi0.95RE0.05)(Fe0.95Mn0.05)O3. It is seen that the coercive field (HC) and remanent magnetization (MR) increase for Gd.

  4. Large spin-relaxation barriers for the low-symmetry organolanthanide complexes [Cp*2 Ln(BPh4 )] (Cp*=pentamethylcyclopentadienyl; Ln=Tb, Dy).

    PubMed

    Demir, Selvan; Zadrozny, Joseph M; Long, Jeffrey R

    2014-07-28

    Single-molecule magnets comprising one spin center represent a fundamental size limit for spin-based information storage. Such an application hinges upon the realization of molecules possessing substantial barriers to spin inversion. Axially symmetric complexes of lanthanides hold the most promise for this due to their inherently high magnetic anisotropies and low tunneling probabilities. Herein, we demonstrate that strikingly large spin reversal barriers of 216 and 331?cm(-1) can also be realized in low-symmetry lanthanide tetraphenylborate complexes of the type [Cp*2 Ln(BPh4 )] (Cp*=pentamethylcyclopentadienyl; Ln=Tb (1) and Dy (2)). The dysprosium congener showed hysteretic magnetization data up to 5.3?K. Further studies of the magnetic relaxation processes of 1 and 2 under applied dc fields and upon dilution within a matrix of [Cp*2 Y(BPh4 )] revealed considerable suppression of the tunneling pathway, emphasizing the strong influence of dipolar interactions on the low-temperature magnetization dynamics in these systems. PMID:24975126

  5. Large magnetocaloric effect in Ln0.5Ca0.5MnO3 (Ln=Gd, DY) compounds: Conseqence of magnetic precursor effect of rare earth ions

    NASA Astrophysics Data System (ADS)

    Das, Kalipada; Paramanik, Tapas; Das, I.

    2015-01-01

    Magnetic, specific heat and magnetocaloric studies have been performed on rare earth calcium manganites; Ln0.5Ca0.5MnO3 (Ln=Gd, Dy). The observed isothermal magnetic entropy change is fairly large at low temperature in the manganites family, which is attributed to the magnetic precursor effect of rare-earth ions. For Gd0.5Ca0.5MnO3, the isothermal magnetic entropy change (-?S) at 4 K, obtained for 7 T magnetic field, is as high as 22.8 J/kg K. On the other hand, -?S is 8.5 J/kg K for Dy0.5Ca0.5MnO3. The large value of magnetic entropy change at the cryogenic temperature range for these compounds is interesting from application point of view.

  6. Spectral characteristics of visible luminescence in Gd2SiO5-Lu2SiO5 (LGSO) solid solution crystals co-doped with Ce3+ and Dy3+

    NASA Astrophysics Data System (ADS)

    Strz?p, Adam; Ryba-Romanowski, Witold; Berkowski, Marek

    2014-11-01

    Two single crystals of LGSO containing 1% Dy3+ and differing in Ce3+ concentration were grown by the Czochralski method. XRD examination revealed that a crystal with a nominal Ce3+ concentration of 3% has the C2/c structure inherent to Lu2SiO5 (LSO) whereas a crystal with a nominal Ce3+ concentration of 1% has the P21/c structure inherent to Gd2SiO5 (GSO). In both crystal structure types the excitation of Ce3+ ions is followed by an energy transfer to Dy3+ ions and resulting visible emission consists of a broad-band Ce3+ luminescence and of much more narrow bands of Dy3+ luminescence. Excitation spectra imply that the efficiency of Dy3+ excitation via Ce3+ - Dy3+ energy transfer is markedly higher than upon direct optical pumping into Dy3+ excited levels. It was observed that visible emission in the two systems differs in spectral characteristics, hence in the colour of the emitted light. Examination of optical spectra recorded with a polarized light revealed important anisotropy of transition intensities of Ce3+ ions in LGSO host with the P21/c structure.

  7. Magnetic properties of quadruple perovskites Ba{sub 4}LnRu{sub 3}O{sub 12} (Ln=La, Nd, Sm-Gd, Dy-Lu)

    SciTech Connect

    Shimoda, Yuki; Doi, Yoshihiro; Wakeshima, Makoto [Division of Chemistry, Hokkaido University, Sapporo 060-0810 (Japan); Hinatsu, Yukio, E-mail: hinatsu@sci.hokudai.ac.j [Division of Chemistry, Hokkaido University, Sapporo 060-0810 (Japan)

    2010-01-15

    Quadruple perovskites Ba{sub 4}LnRu{sub 3}O{sub 12} (Ln=La, Nd, Sm-Gd, Dy-Lu) were prepared and their magnetic properties were investigated. They adopt the 12L-perovskite-type structure consisting of Ru{sub 3}O{sub 12} trimers and LnO{sub 6} octahedra. All of these compounds show an antiferromagnetic transition at 2.5-30 K. For Ba{sub 4}NdRu{sub 3}O{sub 12}, ferrimagnetic ordering has been observed at 11.5 K. The observed magnetic transition is due to the magnetic behavior of the Ru{sup 4.33+}{sub 3}O{sub 12} trimer with S=1/2 . Magnetic properties of Ba{sub 4}LnRu{sub 3}O{sub 12} were compared with those of triple perovskites Ba{sub 3}LnRu{sub 2}O{sub 9} and double perovskites Ba{sub 2}LnRuO{sub 6}. - Graphical abstract: Quadruple perovskites Ba{sub 4}LnRu{sub 3}O{sub 12} (Ln=La, Nd, Sm-Gd, Dy-Lu) were prepared. They adopt the 12L-perovskite-type structure consisting of Ru{sub 3}O{sub 12} trimers and LnO{sub 6} octahedra. All of these compounds show an antiferromagnetic transition at 2.5-30 K. For Ba{sub 4}NdRu{sub 3}O{sub 12}, ferrimagnetic ordering has been observed at 11.5 K. The observed magnetic transition is due to the magnetic behavior of the Ru{sup 4.33+}{sub 3}O{sub 12} trimer with S=1/2 . Magnetic properties of Ba{sub 4}LnRu{sub 3}O{sub 12} were compared with those of triple perovskites Ba{sub 3}LnRu{sub 2}O{sub 9} and double perovskites Ba{sub 2}LnRuO{sub 6}.

  8. Evidence through Mössbauer spectroscopy of two different states for 57Fe probe atoms in RNiO3 perovskites with intermediate-size rare earths, R = Sm,Eu,Gd,Dy

    Microsoft Academic Search

    I. Presniakov; A. Baranov; G. Demazeau; V. Rusakov; A. Sobolev; J. A. Alonso; M. J. Martínez-Lope; K. Pokholok

    2007-01-01

    In the present work, 57Fe probe Mössbauer spectroscopy was developed to study the nickelates RNi0.98Fe0.02O3 (R = Sm,Eu,Gd,Dy) with the perovskite-like structure. The restoration method for a distribution function P(v) of the positions (v) involving individual Lorentzian lines has been used for processing and analysing the Mössbauer spectra. The P(v) profile for the nickelates, at T

  9. Interface structure and strain relaxation in BaTiO3 thin films grown on GdScO3 and DyScO3 substrates with buried coherent SrRuO3 layer

    E-print Network

    Eom, Chang Beom

    substrates with buried coherent SrRuO3 layer Y. B. Chen, H. P. Sun, M. B. Katz, and X. Q. Pana Department grown on GdScO3 and DyScO3 substrates with buried SrRuO3 layers. We found that the different strain the electrical properties of epitaxial ferroelectric thin films, a bottom electrode such as epitaxial SrRuO3

  10. Preparation, patterning and luminescent properties of nanocrystalline Gd 2O 3:A (A=Eu 3+, Dy 3+, Sm 3+, Er 3+) phosphor films via Pechini sol–gel soft lithography

    Microsoft Academic Search

    M. L Pang; J. Lin; J. Fu; R. B Xing; C. X. Luo; Y. C Han

    2003-01-01

    Nanocrystalline Gd2O3:A (A=Eu3+, Dy3+, Sm3+, Er3+) phosphor films and their patterning were fabricated by a Pechini sol–gel process combined with a soft lithography. X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and optical microscopy, UV\\/vis transmission and photoluminescence (PL) spectra as well as lifetimes were used to characterize the resulting films. The results of XRD indicated that

  11. Rare earth niobium oxynitrides, LnNbON{sub 2-{delta}} (Ln = Y, La, Pr, Nd, Gd, Dy): Synthesis, structure and properties

    SciTech Connect

    Kumar, Nitesh; Sundaresan, A. [Chemistry and Physics of Materials Unit, CSIR Centre of Excellence in Chemistry and International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064 (India)] [Chemistry and Physics of Materials Unit, CSIR Centre of Excellence in Chemistry and International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064 (India); Rao, C.N.R., E-mail: cnrrao@jncasr.ac.in [Chemistry and Physics of Materials Unit, CSIR Centre of Excellence in Chemistry and International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064 (India)] [Chemistry and Physics of Materials Unit, CSIR Centre of Excellence in Chemistry and International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064 (India)

    2011-11-15

    Graphical abstract: Ammonolysis of LnNbO{sub 4} (Ln = rare earth or Y) leads to the formation of oxynitrides of different structures depending on the size of the rare earth. Highlights: {yields} We have carried out ammonolysis of LnNbO{sub 4} (Ln = rare earth and Y) to form oxynitrides of different structures depending on the size of the rare earth. {yields} Infrared spectroscopy shows the marked difference between oxides and the corresponding oxynitrides. {yields} The oxynitrides are stable in air upto {approx}400 {sup o}C above which an intermediate phase with nitrogen molecules attached to the oxide lattice forms. {yields} Gadolinium niobium oxynitride shows paramagnetism. -- Abstract: Ammonolysis of rare earth niobates of the type LnNbO{sub 4} (Ln = Y, La, Pr, Nd, Gd, Dy) yields oxynitrides of different structures. When Ln = La, Nd and Pr, the structure is that of an orthorhombic perovskite of the general formula LnNbON{sub 2}. As the size of the rare earth decreases, the oxynitride has a nitrogen-deficient defect fluorite (Ln = Pr, Nd, Gd), or pyrochlore (Ln = Y) structure. The IR spectra of the oxynitrides and the corresponding oxides are significantly different. Thermogravimetric analysis suggests the formation of an intermediate phase wherein the N{sub 2} molecule is attached to the oxide lattice above 400 {sup o}C and decomposes to give the oxide on heating in an oxygen atmosphere. Raman spectra of the intermediate phases show evidence for the N{identical_to}N stretching vibration. Gadolinium niobium oxynitride is found to be paramagnetic.

  12. Suitability of the rare-earth compounds Dy2Ti2O7 and Gd3Al5O12 for low temperature (4K-20K) magnetic refrigeration cycle

    NASA Technical Reports Server (NTRS)

    Flood, D. J.

    1973-01-01

    Measurements were made of the magnetic entropy and magnetization of powered samples of the compounds Dy2Ti2O7 and Gd3Al5O12. The magnetization was measured for temperatures at and below 4.2 K, in applied fields ranging to 7.0 tesla. Isothermal changes in magnetic entropy were measured for temperatures from 1.2 to 20 K, in applied fields up to 10 tesla. The results of the measurements are consistent with a doublet ground state for Dy2Ti2O7, and an eight-fold degenerate ground state for Gd3Al5O12. Absolute values of magnetic entropy have been obtained at the lower temperatures, permitting the isotherms to be properly located in the S-H plane with the use of adiabatic magnetization data. The iso-field lines in the S-T plane were determined. The results indicate that Dy2Ti2O7 can absorb a maximum of 71 + or - 4 joules/kg of heat at 4.2 K, while Gd3Al5O12 can absorb 233 + or - joules/kg at the same temperature. The large difference between the two is most likely a result of crystal field interactions in the dysoprosium compound. Both materials can be cycled adiabatically between 4.2 and 20 K.

  13. The effect of an external magnetic field on the L3 subshell fluorescence yields and level widths for Gd, Dy, Hg and Pb at 59.5 keV

    NASA Astrophysics Data System (ADS)

    Demir, Demet; ?ahin, Yusuf

    2007-01-01

    The effect of external magnetic field on the L3 subshells fluorescence yields ( ?3) and level widths ( ?) for ferromagnetic Gd and Dy and diamagnetic Hg and Pb have been investigated using the 59.5 keV incident photon energy in the external magnetic field of intensities ±0.75 T. L3 X-ray production cross sections ( ?L3X) have been measured for the same elements. The measured ?3, ? and ?L3X values for B = 0 are in good agreement with the theoretical values. It was observed that the values of ?3 and ?L3X with the applied magnitude of the magnetic field in both directions increase for ferromagnetic Gd and Dy but decrease for diamagnetic Hg and Pb. Furthermore, in the presence of an external magnetic field, the values for ?decrease for Gd and Dy, and increase for Hg and Pb. The results show that the atomic parameters such as spectral linewidth, radiation rates, photoionization cross section and fluorescence yield can change when the irradiation is conducted in a magnetic field.

  14. Effect of pressure on octahedral distortions in RCrO3 (R = Lu, Tb, Gd, Eu, Sm): the role of R-ion size and its implications

    NASA Astrophysics Data System (ADS)

    Srinu Bhadram, Venkata; Swain, Diptikanta; Dhanya, R.; Polentarutti, Maurizio; Sundaresan, A.; Narayana, Chandrabhas

    2014-04-01

    The effect of rare-earth ion size on the octahedral distortions in rare-earth chromites (RCrO3, R = Lu, Tb, Gd, Eu, Sm) crystallizing in the orthorhombic structure has been studied using Raman scattering and synchrotron powder x-ray diffraction up to 20 GPa. From our studies on RCrO3 we found that the octahedral tilts (distortions) increase with pressure. This is contrary to the earlier report which suggests that in LaCrO3, the distortions decrease with pressure leading to a more ordered phase at high pressure. Here, we observe that the rate of increase in distortion decreases with the increase in R-ion radii. This occurs due to the reduction in the compression of RO12 polyhedra with a corresponding increase in the compression of the CrO6 octahedra with increasing R-ion radii. From the Raman studies, we predict a critical R-ion radii, above which we expect the distortions in RCrO3 to reduce with increasing pressure leading to what is observed in the case of LaCrO3. These Raman results are consistent with our pressure dependent structural studies on RCrO3 (R = Gd, Eu, Sm). Also, our results suggest that the pressure dependence of Néel temperature, T NCr, (where the Cr3+ spin orders) in RCrO3 is mostly affected by the compressions of Cr-O bonds rather than the alteration of octahedral tilts.

  15. Preparation of new fluorophore lanthanide complexes-Cloisite nanohybrids using the tricationic Pr(III), Gd(III) and Dy(III) complexes with 9,10-phenanthrenequinone.

    PubMed

    Mallakpour, Shadpour; Behnamfar, Mohammad Taghi; Dinari, Mohammad; Hadadzadeh, Hassan

    2015-02-25

    New fluorophore lanthanide complexes-Cloisite (LCs-C) nanohybrids have been prepared by the intercalation reaction of Cloisite Na(+) with the tricationic lanthanide complexes (1-3), [M(PQ)3(DMF)2(H2O)2](3+) (M=Pr(III) (1), Gd(III) (2), and Dy(III) (3); PQ=9,10-phenanthrenequinone), in aqueous solutions. The X-ray diffraction analysis of the modified clays (LCs-C) showed an increase in the interlayer distance (d) as compared to the pure Cloisite Na(+). Field-emission scanning electron microscopy (FE-SEM) was used to study the morphology of the modified clays and the results were demonstrated a homogeneous morphology for the nanohybrids. The thermal behavior of the LCs-C nanohybrids was investigated using thermogravimetric analysis. Solid-state fluorescence properties of the LCs-C nanohybrids were also investigated. The results show that all tricationic complexes have a significant fluorescence at room temperature when the complexes are adsorbed onto Cloisite. PMID:25305612

  16. Preparation, Characterization, and Ionic Transport Properties of Nanoscale Ln2Zr2O7 (Ln = Ce, Pr, Nd, Sm, Gd, Dy, Er, and Yb) Energy Materials

    NASA Astrophysics Data System (ADS)

    Solomon, Sam; George, Aneesh; Thomas, Jijimon Kumpakkattu; John, Annamma

    2015-01-01

    Nanoparticles of lanthanide (Ln)-based zirconates have been prepared through the autoignited combustion technique. The structure of the system was analyzed by powder x-ray diffraction and vibrational spectroscopic tools. The compounds with Ln = Ce, Pr, Nd, Sm, and Gd have pyrochlore cubic structure, whereas those with Ln = Dy, Er, and Yb possess anion-deficient disordered cubic fluorite structure. The optical properties of the powder were analyzed using ultraviolet-visible spectroscopy. Pellets of the compounds were sintered in the range from 1325°C to 1530°C for 2 h. The surface morphology of sintered Nd2Zr2O7 was analyzed by scanning electron microscopy. Impedance spectroscopic studies of the samples were carried out at different temperatures. The conductivity increased to the order of 10-2 S/m at 750°C, and the highest conductivity of 13.21 × 10-2 S/m was obtained for Er2Zr2O7. All samples of this system are suitable candidates for fabrication of electrolytes for use in solid oxide fuel cells, particularly at moderate temperatures.

  17. Synthesis and structure of a new family of 3d-4f heterometallic compounds Rb{sub 7}LnFe{sub 6}O{sub 2}(PO{sub 4}){sub 8} (Ln=Sm, Eu, Gd, Dy): Magnetic properties of the Sm-, Gd-, Dy-derivatives

    SciTech Connect

    Sanjeewa, Liurukara D.; Palmer West, J. [Department of Chemistry, Clemson University, Clemson, SC 29634-0973 (United States); Hwu, Shiou-Jyh, E-mail: shwu@clemson.edu [Department of Chemistry, Clemson University, Clemson, SC 29634-0973 (United States)

    2012-08-15

    A new family of mixed lanthanide(III) and iron(III) oxo-phosphate phases, Rb{sub 7}LnFe{sub 6}O{sub 2}(PO{sub 4}){sub 8} (Ln=Sm 1, Eu 2, Gd 3, Dy 4), was isolated by using a high-temperature, solid-state method in molten-salt media. The X-ray single-crystal structure analysis shows that these isomorphic derivatives crystallize in a triclinic space group P-1 (no. 2); Z=1. The 3-D framework of these 3d-4f oxo-phosphates are comprised of LnO{sub 6} octahedral, FeO{sub 5} trigonal bipyramidal (tbp), and {mu}{sub 3}-oxo [Fe{sub 4}O{sub 18}] tetrameric units interconnected through PO{sub 4} tetrahedra. The preliminary results of the temperature-dependent magnetic susceptibility measurements for selected compounds (1, 3, 4) reveal antiferromagnetic-like behavior. 1 shows a weak antiferromagnetric ordering at T{sub N}={approx}7 K while others show little evidence of long-range magnetic order down to 2 K. All three compounds have measured magnetic moments significantly smaller than the expected values. - Graphical abstract: The extended framework is described by the connectivity of three distinct types of paramagnetic units. The temperature-dependent, lower than expected effective magnetic moments are reported. Highlights: Black-Right-Pointing-Pointer A new family of mixed lanthanide(III) and iron(III) oxo-phosphates is isolated. Black-Right-Pointing-Pointer Features PO{sub 4}-linked paramagnetic units of LnO{sub 6}, FeO{sub 5}, and {mu}{sub 3}-oxo [Fe{sub 4}O{sub 18}]. Black-Right-Pointing-Pointer Sm-derivative orders at T{sub N}{approx}7 K while Gd- and Dy-derivatives show absence of order.

  18. /sup 147/Tb and proton single particle states near Z=64

    SciTech Connect

    Chasman, R.R.

    1980-01-01

    Proton single particle level spacings near Z=64 are deduced from an analysis of low-lying levels in /sup 145/Eu, using a pairing force as the residual interaction. Two forms for the pairing force are explored. Using this spectrum, high spin states in /sup 144/Sm, /sup 146/Gd, and /sup 148/Dy are calculated and compared with known experimental values when possible. The low-lying states in /sup 143/Pm and /sup 147/Tb are also calculated. The need for experimental data on /sup 147/Tb is emphasized.

  19. Rapid, large-scale, morphology-controllable synthesis of YOF:Ln3+ (Ln = Tb, Eu, Tm, Dy, Ho, Sm) nano-/microstructures with multicolor-tunable emission properties.

    PubMed

    Zhang, Yang; Geng, Dongling; Kang, Xiaojiao; Shang, Mengmeng; Wu, Yuan; Li, Xuejiao; Lian, Hongzhou; Cheng, Ziyong; Lin, Jun

    2013-11-18

    YOF:Ln(3+) (Ln = Tb, Eu, Tm, Dy, Ho, Sm) nano-/microstructures with a variety of novel and well-defined morphologies, including nanospheres, nanorod bundles, and microspindles, have been prepared through a convenient modified urea-based homogeneous precipitation (UBHP) technique followed by a heat treatment. The sizes and morphologies of the YOF products could be easily modulated by changing the pH values and fluoride sources. XRD, TG-DTA, FT-IR, SEM, and TEM, as well as photoluminescence (PL) and cathodoluminescence (CL) spectra, were used to characterize the prepared samples. The YOF:Ln(3+) nanospheres show the characteristic f-f transitions of Ln(3+) (Ln = Tb, Eu, Tm, Dy, Ho, Sm) ions and give bright green, red, blue, yellow, blue-green, and yellow-orange emission, respectively, under UV light and low-voltage electron beam excitation. Furthermore, YOF:0.03Tb(3+) phosphors exhibit green luminescence with superior properties in comparison with the commercial phosphor ZnO:Zn to a degree, which is advantageous for improving display quality. Because of the simultaneous luminescence of Ln(3+) in the YOF host, the luminescence colors of YOF:Ln(3+) phosphors can be precisely adjusted by changing the doped Ln(3+) ions and corresponding concentrations, which makes these materials hold great promise for applications in field-emission displays. PMID:24195545

  20. Vibrational and electronic properties of the lanthanide trifluorides GdF 3, TbF 3, ErF 3 and YbF 3 studied by Raman spectroscopy

    Microsoft Academic Search

    K. Rotereau; Ph. Daniel; J. Y. Gesland

    1998-01-01

    Single crystals of GdF3, TbF3, ErF3, YbF3 have been studied by Raman scattering at 10 K and at room temperature when they exhibit orthorhombic symmetry of the ?-YF3 type. Based on group theory analysis and selection rules, Raman spectra have been fully interpreted with the help of the results obtained for the structural archetype YF3. Among the expected 24 Raman

  1. A new type of silica-coated Gd2(CO3)3:Tb nanoparticle as a bifunctional agent for magnetic resonance imaging and fluorescent imaging

    NASA Astrophysics Data System (ADS)

    Wu, Yanli; Xu, Xianzhu; Tang, Qun; Li, Yongxiu

    2012-05-01

    We report a new type of dual modal nanoprobe to combine optical and magnetic resonance bioimaging. A simple reverse microemulsion method and coating process was introduced to synthesize silica-coated Gd2(CO3)3:Tb nanoparticles, and the particles, with an average diameter of 16 nm, can be dispersed in water. As in vitro cell imaging of the nanoprobe shows, the nanoprobe accomplishes delivery to gastric SGC7901 cancer cells successfully in a short time, as well as NCI-H460 lung cancer cells. Furthermore, it presents no evidence of cell toxicity or adverse affect on kidney cell growth under high dose, which makes the nanoprobe’s optical bioimaging modality available. The possibility of using the nanoprobe for magnetic resonance imaging is also demonstrated, and the nanoprobe displays a clear T1-weighted effect and could potentially serve as a bimodal T1-positive contrast agent. Therefore, the new nanoprobe formed from carbonate nanoprobe doped with rare earth ions provides the dual modality of optical and magnetic resonance imaging.

  2. Structural investigation of the new Ca{sub 3}Ln{sub 2}Ge{sub 3}O{sub 12} (Ln=Pr, Nd, Sm, Gd and Dy) compounds and luminescence spectroscopy of Ca{sub 3}Gd{sub 2}Ge{sub 3}O{sub 12} doped with the Eu{sup 3+} ion

    SciTech Connect

    Piccinelli, F., E-mail: fabio.piccinelli@univr.it [Luminescent Materials Laboratory, DB, Univ. Verona, and INSTM, UdR Verona, Strada Le Grazie 15, 37134 Verona (Italy); Lausi, A. [Elettra-Sincrotrone Trieste S.C.p.A., Strada Statale 14-km 163,5 in AREA Science Park, 34149 Basovizza, Trieste (Italy); Bettinelli, M. [Luminescent Materials Laboratory, DB, Univ. Verona, and INSTM, UdR Verona, Strada Le Grazie 15, 37134 Verona (Italy)

    2013-09-15

    The crystal structures of new rare earth-based germanate compounds (Ca{sub 3}Pr{sub 2}Ge{sub 3}O{sub 12}, Ca{sub 3}Nd{sub 2}Ge{sub 3}O{sub 12}, Ca{sub 3}Sm{sub 2}Ge{sub 3}O{sub 12}, Ca{sub 3}Gd{sub 2}Ge{sub 3}O{sub 12} and Ca{sub 3}Dy{sub 2}Ge{sub 3}O{sub 12}) have been determined by Rietveld refinement calculations on the collected synchrotron X-ray diffraction powder patterns. A different distribution of the rare earth ions in the three available crystal sites was observed, as the main structural feature. The reasons of the instability of the silico-carnotite structure for lanthanide ions out of the range Pr–Dy have been proposed. Finally, the luminescence spectroscopy of the Eu{sup 3+} dopant ion in Ca{sub 3}Gd{sub 2}Ge{sub 3}O{sub 12} was presented and analyzed taking into account the observed structural characteristics. The Eu{sup 3+} luminescence spectroscopy was also compared with the one of Eu{sup 3+} doped Ca{sub 3}Gd{sub 2}Si{sub 3}O{sub 12} and Ca{sub 3}Lu{sub 2}Si{sub 3}O{sub 12} isostructural materials. - Graphical abstract: The structural study on Ca{sub 3}Ln{sub 2}Ge{sub 3}O{sub 12} exploiting synchrotron X-ray diffraction, allows us to determine the detailed geometry of the coordination polyhedra of the metals and their distribution in the crystal sites. These features are, in the case of Ca{sub 3}Gd{sub 2}Ge{sub 3}O{sub 12} host, closely related to the luminescence spectroscopy of the Eu{sup 3+} dopant ion. Display Omitted - Highlights: • The structure of the Ca{sub 3}Ln{sub 2}Ge{sub 3}O{sub 12} (Ln=Pr, Nd, Sm, Gd and Dy) was determined. • Different distribution of Ln{sup 3+} ions on the three available crystal sites was observed. • A detailed structural study focused on the metal coordination polyhedra was performed. • The instability of the silico-carnotite structure out of the range Pr–Dy was discussed. • The luminescence of the dopant Eu{sup 3+} ion in Ca{sub 3}Gd{sub 2}Ge{sub 3}O{sub 12} was presented and analyzed.

  3. The VUV-vis spectroscopic properties of phosphors Ca{sub 3}Gd{sub 2(1-x)}Ln{sub 2x}(BO{sub 3}){sub 4} (Ln{sup 3+} = Ce, Sm, Eu, Tb)

    SciTech Connect

    Liang Hongbin [State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou, Guangdong 510275 (China)]. E-mail: cesbin@mail.sysu.edu.cn; Su Qiang [State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou, Guangdong 510275 (China); Key Laboratory of Rare Earth Chemistry and Physics, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China); Tao Ye [Laboratory of Beijing Synchrotron Radiation, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039 (China); Xu Jianhua [Laboratory of Beijing Synchrotron Radiation, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039 (China); Huang Yan [Laboratory of Beijing Synchrotron Radiation, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039 (China)

    2006-08-10

    The spectroscopic properties in VUV-vis range for phosphors calcium and gadolinium double borate Ca{sub 3}Gd{sub 2}(BO{sub 3}){sub 4} doped with rare-earth ions Ce{sup 3+}, Sm{sup 3+}, Eu{sup 3+} and Tb{sup 3+} were investigated. The host-related absorption, the f-d transitions of Ce{sup 3+} and Tb{sup 3+}, as well as the charge transfer transitions of Sm{sup 3+} and Eu{sup 3+} in the host lattice are assigned and discussed. The CIE chromaticity coordinates for Eu{sup 3+}- and Tb{sup 3+}-activated phosphors are calculated.

  4. Electrochemical behavior of Ln 0.6Sr 0.4Co 0.2Fe 0.8O 3? ? (Ln=Ce, Gd, Sm, Dy) materials used as cathode of IT-SOFC

    Microsoft Academic Search

    Jianfeng Gao; Xingqin Liu; Dingkun Peng; Guangyao Meng

    2003-01-01

    The perovskite-type compounds Ln0.6Sr0.4Co0.2Fe0.8O3?? (Ln=Ce, Sm, Gd, Dy) used as the cathodes of intermediate temperature solid oxide fuel cell (IT-SOFC) were studied. The cells consisted of anode supported Sm-doped-ceria electrolyte bi-layer and cathode with 0.65cm2 effective area. Open-circuit voltage (OCV), V–I and P–I curves of the cells were measured over a temperature range from 400 to 800°C, using H2–3%H2O as

  5. Novel photofunctional multicomponent rare earth (Eu3+, Tb3+, Sm3+ and Dy3+) hybrids with double cross-linking siloxane covalently bonding SiO2/ZnS nanocomposite.

    PubMed

    Yan, Bing; Zhao, Yan; Li, Ya-Juan

    2011-01-01

    Zinc sulfide (ZnS) quantum dot is modified with 3-mercaptopropyltrimethoxysilane (MPTMS) to obtain MPTMS functionalized SiO(2)/ZnS nanocomposite. Novel rare earth/inorganic/organic hybrid materials are prepared by using 3-(triethoxysilyl)-propyl isocyanate (TESPIC) as an organic bridge molecule that can both coordinate to rare earth ions (Eu(3+), Tb(3+), Sm(3+) and Dy(3+)) and form an inorganic Si-O-Si network with SiO(2) ZnS nanocomposite after cohydrolysis and copolycondensation through a sol-gel process. These multicomponent hybrids with double cross-linking siloxane (TESPIC-MPTMS) covalently bonding SiO(2)/ZnS and assistant ligands (Phen = 1,10-phenanthroline, Bipy = 2,2'-bipyridyl) are characterized and especially the photoluminescence properties of them are studied in detail. The luminescent spectra of the hybrids show the dominant excitation of TESPIC-MPTMS-SiO(2)/ZnS unit and the unique emission of rare earth ions, suggesting that TESPIC-MPTMS-SiO(2)/ZnS unit behaves as the main energy donor and effective energy transfer take place between it and rare earth ions. Besides, the luminescent performance of Bipy-RE-TESPIC-MPTM-SiO(2)/ZnS hybrids are superior to that of Phen-RE-TESPIC-MPTMS-SiO(2)/ZnS ones (RE=Eu, Tb, Sm, Dy), which reveals that Bipy or Phen only act as structural ligand within the hybrid systems. PMID:21401615

  6. Electronic structure of rare-earth chromium antimonides RECrSb{sub 3} (RE=La-Nd, Sm, Gd-Dy, Yb) by X-ray photoelectron spectroscopy

    SciTech Connect

    Crerar, Shane J. [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada)] [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada); Mar, Arthur, E-mail: arthur.mar@ualberta.ca [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada)] [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada); Grosvenor, Andrew P. [Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5C9 (Canada)] [Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5C9 (Canada)

    2012-12-15

    The electronic structure of the ternary rare-earth chromium antimonides RECrSb{sub 3} (RE=La-Nd, Sm, Gd-Dy, Yb) has been examined by high-resolution X-ray photoelectron spectroscopy (XPS) for the first time. The RE 3d or 4d core-line spectra are substantially complicated by the presence of satellite peaks but their general resemblance to those of RE{sub 2}O{sub 3} tends to support the presence of trivalent RE atoms in RECrSb{sub 3}. However, the Yb 4d spectrum of YbCrSb{sub 3} also shows peaks that are characteristic of divalent ytterbium. The Cr 2p core-line spectra exhibit asymmetric lineshapes and little change in binding energy (BE) relative to Cr metal, providing strong evidence for electronic delocalization. The Sb 3d core-line spectra reveal slightly negative BE shifts relative to elemental antimony, supporting the presence of anionic Sb species in RECrSb{sub 3}. The experimental valence band spectrum of LaCrSb{sub 3} matches well with the calculated density of states, and it can be fitted to component peaks belonging to individual atoms to yield an average formulation that agrees well with expectations ('La{sup 3+}Cr{sup 3+}(Sb{sup 2-}){sub 3}'). On progressing from LaCrSb{sub 3} to NdCrSb{sub 3}, the 4f-band in the valence band spectra grows in intensity and shifts to higher BE. The valence band spectrum for YbCrSb{sub 3} also supports the presence of divalent ytterbium. - Graphical Abstract: In their valence band spectra, the 4f-band intensifies and shifts to higher BE on progressing from LaCrSb{sub 3} to NdCrSb{sub 3}. Highlights: Black-Right-Pointing-Pointer High-resolution core-line and valence band XPS spectra were measured for RECrSb{sub 3}. Black-Right-Pointing-Pointer Divalent Yb is present in YbCrSb{sub 3}, in contrast to trivalent RE in other members. Black-Right-Pointing-Pointer Asymmetric Cr 2p spectral lineshape confirms delocalization of Cr valence electrons. Black-Right-Pointing-Pointer Small negative Sb 3d BE shifts support assignment of anionic Sb atoms. Black-Right-Pointing-Pointer Fitted valence band spectra show shifts in the 4f band as RE is changed.

  7. Synthesis, magnetism, and 57Fe Mössbauer spectroscopic study of a family of [Ln3Fe7] coordination clusters (Ln = Gd, Tb, and Er).

    PubMed

    Abbas, Ghulam; Lan, Yanhua; Mereacre, Valeriu; Buth, Gernot; Sougrati, Moulay T; Grandjean, Fernande; Long, Gary J; Anson, Christopher E; Powell, Annie K

    2013-10-21

    The reaction of N-methydiethanolamine (mdeaH2), benzoic acid, FeCl3, and Ln(NO3)3·6H2O or LnCl3·xH2O yields a series of decanuclear coordination clusters, [Ln3Fe7(?4-O)2(?3-OH)2(mdea)7(?-benzoate)4(N3)6]·4MeCN·H2O, where Ln = Gd(III) (1) or Tb(III) (2), and [Er3Fe7(?4-O)2(?3-OH)2(mdea)7(?-benzoate)4(N3)5(MeOH)]Cl·7.5H2O·11.5MeOH (3). The isostructural compounds 1-3 all crystallize isotypically in the triclinic space group P1? with Z = 2, as does the previously reported dysprosium analogue 4. Six of the Fe(III) ions are pseudooctahedrally coordinated, whereas the seventh has a trigonal-bipyramidal coordination geometry. Temperature-dependent direct-current magnetic susceptibility studies indicate that intracluster antiferromagnetic interactions are dominant in 1-3. The frequency-dependent out-of-phase (??) alternating-current susceptibility reveals that 2 undergoes a slow relaxation of its magnetization, presumably resulting from anisotropy of the Tb(III) ions. Between 30 and 295 K, the (57)Fe Mössbauer spectra reveal paramagnetic behavior with six partially resolved quadrupole doublets, one for the trigonal-bipyramidal Fe(III) site and five for the six pseudooctahedral Fe(III) sites. The Mössbauer spectra of 2 and 3 obtained between 3 and 30 K are consistent with the presence of Fe(III) intracluster antiferromagnetic coupling with slow magnetic relaxation relative to the Larmor precession time. Further, the observed changes in the effective magnetic field values in the spectra measured at 3 K with increasing applied field are consistent with the effect of the local spin polarization along the applied magnetic field direction, a behavior reminiscent of antiparallel spin-coupled iron molecular paramagnetic systems. PMID:24089701

  8. Syntheses and characterization of zero-dimensional molybdoantimonites, A {sub 2}(Mo{sub 4}Sb{sub 2}O{sub 18}) (A=Y, La, Nd, Sm, Gd and Dy)

    SciTech Connect

    Kalpana, G. [Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036 (India); Vidyasagar, K. [Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036 (India)], E-mail: kvsagar@iitm.ac.in

    2007-05-15

    Six new isostructural A {sub 2}(Mo{sub 4}Sb{sub 2}O{sub 18}) (A=Y, La, Nd, Sm, Gd and Dy) compounds have been synthesized by solid-state reactions and characterized by single crystal X-ray diffraction and spectroscopic techniques. They crystallize in C2/c space group with 4 formula units and contain A{sup 3+} cations and discrete centrosymmetric anionic (Mo{sub 4}Sb{sub 2}O{sub 18}){sup 6-} aggregates, made of tetrahedral MoO{sub 4} and disphenoidal SbO{sub 4} moieties. They exhibit characteristic Sb{sup 3+} photoluminescence. - Graphical abstract: Six isostructural A {sub 2}(Mo{sub 4}Sb{sub 2}O{sub 18}) (A=Y, La, Nd, Sm, Gd and Dy) compounds, containing discrete, centrosymmetric anionic (Mo{sub 4}Sb{sub 2}O{sub 18}){sup 6-} aggregates, exhibit characteristic Sb{sup 3+} photoluminescence.

  9. Color-tunable emission and energy transfer in Ca3Gd7(PO4)(SiO4)5O2: Ce3+/Tb3+/Mn2+ phosphors.

    PubMed

    Zhang, Yang; Li, Guogang; Geng, Dongling; Shang, Mengmeng; Peng, Chong; Lin, Jun

    2012-11-01

    Ce(3+)-, Tb(3+)-, and Mn(2+)-activated Ca(3)Gd(7)(PO(4))(SiO(4))(5)O(2) (CGPS) silicate-phosphate oxyapatite phosphors have been prepared via conventional solid-state reaction processes. The Ce(3+) emission at different lattice sites has been identified and discussed. The dual energy transfer of Ce(3+) ? Tb(3+) and Ce(3+) ? Mn(2+) has been investigated. The energy transfer from Ce(3+) to Mn(2+) in CGPS phosphors has been demonstrated to be a resonant type via a dipole-quadrupole mechanism, and the critical distances (R(C)) for Ce(3+) to Mn(2+) calculated by the concentration quenching and spectral overlap methods are 9.71 and 9.15 Å, respectively. A color-tunable emission in CGPS phosphors can be realized by Ce(3+) ? Tb(3+) or Ce(3+) ? Mn(2+) energy transfer. CGPS:0.05Ce(3+)/ 0.15Tb(3+) shows the optimum green emission. Meanwhile, white cathodoluminescence (CL) has been realized in a single-phased Ca(3)Gd(7)(PO(4))(SiO(4))(5)O(2) host by codoping with Ce(3+) and Mn(2+) with CIE (0.322, 0.326). Furthermore, the CL properties of CGPS:Ce(3+)/Tb(3+)/Mn(2+) phosphors, including the dependence of the CL intensity on the accelerating voltage and filament current, the decay behavior of the CL intensity under electron bombardment, and the stability of the CIE chromaticity coordinates, have been investigated in detail. Because of the good CL properties and good CIE chromaticity coordinates, the as-prepared phosphors have potential application in field emission display devices. PMID:23075230

  10. Synthesis, phase composition modification, and optical properties of Ce{sup 3+}/Tb{sup 3+} activated KGdF{sub 4} and GdF{sub 3} submicrocrystals

    SciTech Connect

    Cao Chunyan [College of Mathematics and Physics, Jinggangshan University, Ji'an 343009 (China); Yang, Hyun Kyoung; 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); Kim, Kwang Ho, E-mail: kwhokim@pusan.ac.kr [School of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of)

    2012-03-15

    Ce{sup 3+}/Tb{sup 3+} co-doped series of samples have been synthesized based on a citric acid assisted hydrothermal method. By controlling the hydrothermal treating time, the samples evolve from the Ce{sup 3+}/Tb{sup 3+} co-doped cubic phase KGdF{sub 4} with spherical morphology into the Ce{sup 3+}/Tb{sup 3+} co-doped orthorhombic phase GdF{sub 3} with rhombic shape finally. The X-ray diffraction data illustrate the phase composition modification process of the samples. The field emission scanning electron microscopy and the transmission electron microscopy images suggest the transformation in the morphology of final products. The spectra of the energy-dispersive spectroscopy reveal the constituents of the samples. And the selected area electronic diffraction patterns prove the crystalline phases of the samples. Based on previous studies and the experimental data, one possible phase composition modification process has been summarized. The photoluminescence excitation and emission spectra and the luminescent dynamic decay curves demonstrate the variations in optical properties of the Ce{sup 3+}/Tb{sup 3+} co-doped final products. - Graphical abstract: Schematic illustration for the phase composition modification from the Ce{sup 3+}/Tb{sup 3+} doped KGdF{sub 4} to the Ce{sup 3+}/Tb{sup 3+}doped GdF{sub 3} with multiform morphologies and different sizes. (C presents cubic phase, H presents hexagonal phase, and O presents orthorhombic phase.) Highlights: Black-Right-Pointing-Pointer The samples were synthesized by a hydrothermal method. Black-Right-Pointing-Pointer The samples evolved from the cubic phase KGdF{sub 4} into the orthorhombic phase GdF{sub 3}. Black-Right-Pointing-Pointer The morphology evolved from the spherical shape into the rhombic shape finally. Black-Right-Pointing-Pointer A possible phase composition modification process was summarized. Black-Right-Pointing-Pointer The optical properties of final products were compared and studied.

  11. Re-dispersion and film formation of GdVO4?:? Ln3+ (Ln3+ = Dy3+, Eu3+, Sm3+, Tm3+) nanoparticles: particle size and luminescence studies.

    PubMed

    Shanta Singh, N; Ningthoujam, R S; Phaomei, Ganngam; Singh, S Dorendrajit; Vinu, A; Vatsa, R K

    2012-04-21

    GdVO(4)?:?Ln(3+) (Ln(3+) = Dy(3+), Eu(3+), Sm(3+), Tm(3+)) nanoparticles are prepared by a simple chemical route at 140 °C. The crystallite size can be tuned by varying the pH of the reaction medium. Interestingly, the crystallite size is found to increase significantly when pH increases from 6 to 12. This is related to slower nucleation of the GdVO(4) formation with increase of VO(4)(3-) present in solution. The luminescence study shows an efficient energy transfer from vanadate absorption of GdVO(4) to Ln(3+) and thereby enhanced emissions are obtained. A possible reaction mechanism at different pH values is suggested in this study. As-prepared samples are well dispersed in ethanol, methanol and water, and can be incorporated into polymer films. Luminescence and its decay lifetime studies confirm the decrease in non-radiative transition probability with the increase of heat treatment temperature. Re-dispersed particles will be useful in potential applications of life science and the film will be useful in display devices. PMID:22334276

  12. 2?[Bi2Cl6(pyz)4]: a 2D-pyrazine coordination polymer as soft host lattice for the luminescence of the lanthanide ions Sm3+, Eu3+, Tb3+, and Dy3+.

    PubMed

    Heine, Johanna; Wehner, Tobias; Bertermann, Rüdiger; Steffen, Andreas; Müller-Buschbaum, Klaus

    2014-07-21

    The 2D-coordination polymer (2)?[Bi2Cl6(pyz)4] was synthesized from BiCl3 and a self-consuming melt of pyrazine (pyz). It proves to be a suitable soft host lattice for in situ co-doping of the lanthanide ions Sm(3+), Eu(3+), Tb(3+), and Dy(3+) during network formation. The series of luminescent networks (2)?[Bi(2-x)LnxCl6(pyz)4] obtained exhibits an efficient antenna effect on the lanthanide ions. Emission is almost exclusively observed from the lanthanide centers at room temperature, whereas cooling to 77 K reveals a bismuth-pyrazine metal-to-ligand charge transfer related phosphorescence, which is also present without lanthanide participation. All parts of the coordination polymer can function for light uptake. Partial substitution is achieved by statistic replacement of bismuth with lanthanides and can range up to 25 at. % for trivalent europium. PMID:24963536

  13. Crystal structures of RPt{sub 3-x}Si{sub 1-y}(R=Y, Tb, Dy, Ho, Er, Tm, Yb) studied by single crystal X-ray diffraction

    SciTech Connect

    Gribanov, Alexander [Institute of Physical Chemistry, University of Vienna, Waehringerstrasse 42, A-1090 Wien (Austria); Chemistry Department of the Moscow State University, Leninskie Gory, GSP-1, 119991 Moscow (Russian Federation); Grytsiv, Andriy [Institute of Physical Chemistry, University of Vienna, Waehringerstrasse 42, A-1090 Wien (Austria); Rogl, Peter, E-mail: peter.franz.rogl@univie.ac.a [Institute of Physical Chemistry, University of Vienna, Waehringerstrasse 42, A-1090 Wien (Austria); Seropegin, Yurii [Chemistry Department of the Moscow State University, Leninskie Gory, GSP-1, 119991 Moscow (Russian Federation); Giester, Gerald [Institute of Mineralogy and Crystallography, University of Vienna, Althanstrasse 14, A-1090 Wien (Austria)

    2009-07-15

    The crystal structures of ternary compounds RPt{sub 3-x}Si{sub 1-y}(R=Y, Tb, Dy, Ho, Er, Tm, Yb) have been elucidated from X-ray single crystal CCD data. All compounds are isotypic and crystallize in the tetragonal space group P4/mbm. The general formula RPt{sub 3-x}Si{sub 1-y} arises from defects: x{approx}0.20, y{approx}0.14. The crystal structure of RPt{sub 3-x}Si{sub 1-y} can be considered as a packing of four types of building blocks which derive from the CePt{sub 3}B-type unit cell by various degrees of distortion and Pt, Si-defects. - Graphical Abstract: Electron density in RPt{sub 3-x}Si{sub 1-y} at 0, 1/2 , 0.

  14. Magnetic and magneto-optical properties of rare-earth transition-metal alloys containing Dy, Ho, Fe, Co

    SciTech Connect

    Hansen, P.; Klahn, S.; Clausen, C.; Much, G.; Witter, K. (Philips GmbH Forschungslaboratorium Hamburg, Vogt-Koelln-Strasse 30, D-2000 Hamburg 54, Federal Republic of Germany (DE))

    1991-03-01

    Amorphous rare-earth transition-metal alloys of composition RE{sub l{minus}{ital x}}TM{sub {ital x}} with RE=Dy, Ho; TM=Fe,Co and 0{lt}{ital x}{lt}1 and Dy{sub l{minus}{ital x}}(Fe,Co){sub {ital x}} were prepared by evaporation. The saturation magnetization, uniaxial anisotropy, coercivity, and Faraday rotation were investigated as a function of composition and temperature. Also, the spectral variation of the Kerr rotation was measured. The magnetization data indicate a strong dispersion of the RE moments due to randomly oriented local crystal field axes. The strong turndown of the Curie temperature for the Fe-rich alloys suggests that an additional dispersion is present in the Fe subnetwork. The mean field theory was used to analyze the temperature variation of the magnetization yielding smaller TM spin values and exchange coupling constants as compared with those of the Gd and Tb analogs. The uniaxial anisotropy constant {ital K}{sub {ital u}} for Dy-Co based alloys was found to vary with the square of the Dy subnetwork magnetization as predicted by the random single-ion theory. The anisotropy of Dy-Fe and Ho based alloys require additionally dipolar terms to account for the measured temperature dependence of {ital K}{sub {ital u}}. The coercive field {ital H}{sub {ital c}} follows a relation {ital H}{sub {ital c}} {similar to} {ital K}{sup 1.5}{sub {ital u}}/{ital M}{sub {ital s}}. The magneto-optical effects are primarily caused by the transition metals and therefore their compositional, temperature, and spectral dependence correspond to that of their Gd and Tb analogs. Optical recording experiments on Dy-FeCo disks yield good write and erase sensitivities and carrier-to-noise ratios up to 60 dB which are comparable to those of GdTb-Fe and Tb-FeCo disks.

  15. Synthesis and VUV UV spectroscopic properties of rare earth borosilicate oxyapatite: RE5Si2BO13:Ln3+ (RE=La, Gd, Y; Ln=Eu, Tb)

    Microsoft Academic Search

    Jun-Lin Yuan; Zhi-Jun Zhang; Xiao-Jun Wang; Hao-Hong Chen; Jing-Tai Zhao; Guo-Bin Zhang; Chao-Shu Shi

    2007-01-01

    Three rare earth borosilicate oxyapatites, RE5Si2BO13 (RE=La, Gd, Y), were synthesized via wet chemical method, of which RE5Si2BO13 (RE=Gd, Y) were first reported in this work. In the three oxyapatites, [BO4] and [SiO4] share the [TO4] tetrahedral oxyanion site, and RE3+ ions occupy all metal sites. The differential scanning calorimetry thermo gravimetry measurements and high temperature powder X-ray diffraction pattern

  16. Dy–Mn–Si as a representative of family of ‘Dy–Transition Metal–Si’ systems: Its isothermal sections, empirical rProd. Type: FTPules and new rare-earth manganese silicides

    SciTech Connect

    Morozkin, A.V., E-mail: morozkin@general.chem.msu.ru [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Knotko, A.V. [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Yapaskurt, V.O. [Department of Petrology, Geological Faculty, Moscow State University, Leninskie Gory, Moscow 119992 (Russian Federation); Provino, A.; Manfrinetti, P. [INFM and Dipartimento di Chimica e Chimica Industriale, Universita di Genova, Via Dodecaneso 31, 16146 Genova (Italy); Yao, Jinlei; Yuan, Fang; Mozharivskyj, Y. [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1 (Canada)

    2013-10-15

    X-ray and microprobe analyses were employed for the investigation of Dy–Mn–Si system at 870/1070/1170 K. The Dy–Mn–Si system, contains the known DyMn{sub 2}Si{sub 2}, DyMnSi and Dy{sub 2}Mn{sub 3}Si{sub 5} compounds and DyMn{sub 4}Si{sub 2}, Dy{sub 2}MnSi{sub 2} and Dy{sub 3}Mn{sub 2}Si{sub 3} were new compounds identified first time and their structure are of the type TmCu{sub 4}Sb{sub 2}, Sc{sub 2}CoSi{sub 2} and Hf{sub 3}Ni{sub 2}Si{sub 3} respectively. The quasi-binary solid solutions were detected at 870/1070/1170 K: the ThMn{sub 12}-type Dy{sub 8}Mn{sub 87}Si{sub 5}, Th{sub 6}Mn{sub 23}-type Dy{sub 23}Mn{sub 72}Si{sub 5}, MgCu{sub 2}-type Dy{sub 33}Mn{sub 58}Si{sub 9} and AlB{sub 2}-type Dy{sub 38}Mn{sub 2}Si{sub 58}. The other binary compounds of the Dy–Mn–Si system do not show any visible solubility. New phases R{sub 2}MnSi{sub 2} and R{sub 3}Mn{sub 2}Si{sub 3} (R=Gd, Tb, Ho–Tm) were found out and their structure of the type Sc{sub 2}CoSi{sub 2} and Hf{sub 3}Ni{sub 2}Si{sub 3} respectively. The specific features of ‘Dy–Transition Metal–Si’ systems were discussed. - Graphical abstract: The isothermal section of Dy–Mn–Si contains the known DyMn{sub 2}Si{sub 2}, DyMnSi, Dy{sub 2}Mn{sub 3}Si{sub 5} and new TmCu{sub 4}Sb{sub 2}-type DyMn{sub 4}Si{sub 2}, Sc{sub 2}CoSi{sub 2}-type Dy{sub 2}MnSi{sub 2} and Hf{sub 3}Ni{sub 2}Si{sub 3}-type Dy{sub 3}Mn{sub 2}Si{sub 3} ternary compounds. The ternary solid solution based on the binary compounds of the Dy–Mn and Dy–Si systems: the ThMn{sub 12}-type Dy{sub 8}Mn{sub 87}Si{sub 5}, Th{sub 6}Mn{sub 23}-type Dy{sub 23}Mn{sub 72}Si{sub 5}, MgCu{sub 2}-type Dy{sub 33}Mn{sub 58}Si{sub 9} and AlB{sub 2}-type Dy{sub 38}Mn{sub 2}Si{sub 58}. The other binary compounds of the Dy–Mn–Si system do not show any visible solubility. New Sc{sub 2}CoSi{sub 2}-type R{sub 2}MnSi{sub 2} and Hf{sub 3}Ni{sub 2}Si{sub 3}-type R{sub 3}Mn{sub 2}Si{sub 3} phases were discovered for R=Gd, Tb, Ho–Tm. Display Omitted - Highlights: • The Dy–Mn–Si section contains three known and three new ternary compounds (phases). • New phase the TmCu{sub 4}Sb{sub 2}-type DyMn{sub 4}Si{sub 2} compound. • New Sc{sub 2}CoSi{sub 2}-type R{sub 2}MnSi{sub 2} and Hf{sub 3}Ni{sub 2}Si{sub 3}-type R{sub 3}Mn{sub 2}Si{sub 3} were detected for R=Gd–Tm. • Dy–Mn–Si supplements the ‘Dy–3d metal–Si’ series and leads to the ‘RT{sub m}X{sub n}’ row's rule.

  17. Structure determination of KScS2, RbScS2 and KLnS2 (Ln = Nd, Sm, Tb, Dy, Ho, Er, Tm and Yb) and crystal-chemical discussion.

    PubMed

    Havlák, Lubomír; Fábry, Jan; Henriques, Margarida; Dušek, Michal

    2015-07-01

    The title structures of KScS2 (potassium scandium sulfide), RbScS2 (rubidium scandium sulfide) and KLnS2 [Ln = Nd (potassium neodymium sufide), Sm (potassium samarium sulfide), Tb (potassium terbium sulfide), Dy (potassium dysprosium sulfide), Ho (potassium holmium sulfide), Er (potassium erbium sulfide), Tm (potassium thulium sulfide) and Yb (potassium ytterbium sulfide)] are either newly determined (KScS2, RbScS2 and KTbS2) or redetermined. All of them belong to the ?-NaFeO2 structure type in agreement with the ratio of the ionic radii r(3+)/r(+). KScS2, the member of this structural family with the smallest trivalent cation, is an extreme representative of these structures with rare earth trivalent cations. The title structures are compared with isostructural alkali rare earth sulfides in plots showing the dependence of several relevant parameters on the trivalent cation crystal radius; the parameters thus compared are c, a and c/a, the thicknesses of the S-S layers which contain the respective constituent cations, the sulfur fractional coordinates z(S(2-)) and the bond-valence sums. PMID:26146403

  18. Photoluminescent properties of Eu 3+, Tb 3+ activated M 3Ln(PO 4) 3 (M = Sr, Ca; Ln = Y, La, Gd) phosphors derived from hybrid precursors

    Microsoft Academic Search

    Xiuzhen Xiao; Shuai Xu; Bing Yan

    2007-01-01

    Ternary orthophosphates M3Ln(PO4)3 doped with Eu3+, Tb3+ were prepared via an in situ chemical co-precipitation technology, and the assembly process of hybrid precursors were as follows: using rare-earth coordination polymers with salicylic acid as precursors and composing with the polyvinyl alcohol (PVA) as dispersing media. Their microstructure and micromorphology have been analyzed by X-ray powder diffraction (XRD) and scanning electron

  19. Luminescence and energy transfer properties of Ca2Ba3(PO4)3Cl and Ca2Ba3(PO4)3Cl:A (A = Eu2+/Ce3+/Dy3+/Tb3+) under UV and low-voltage electron beam excitation.

    PubMed

    Shang, Mengmeng; Geng, Dongling; Yang, Dongmei; Kang, Xiaojiao; Zhang, Yang; Lin, Jun

    2013-03-18

    Pure Ca2Ba3(PO4)3Cl and rare earth ion (Eu(2+)/Ce(3+)/Dy(3+)/Tb(3+)) doped Ca2Ba3(PO4)3Cl phosphors with the apatite structure have been prepared via a Pechini-type sol-gel process. X-ray diffraction (XRD) and structure refinement, photoluminescence (PL) spectra, cathodoluminescence (CL) spectra, absolute quantum yield, as well as lifetimes were utilized to characterize samples. Under UV light excitation, the undoped Ca2Ba3(PO4)3Cl sample shows broad band photoluminescence centered near 480 nm after being reduced due to the defect structure. Eu(2+) and Ce(3+) ion doped Ca2Ba3(PO4)3Cl samples also show broad 5d ? 4f transitions with cyan and blue colors and higher quantum yields (72% for Ca2Ba3(PO4)3Cl:0.04Eu(2+); 67% for Ca2Ba3(PO4)3Cl:0.016Ce(3+)). For Dy(3+) and Tb(3+) doped Ca2Ba3(PO4)3Cl samples, they give strong line emissions coming from 4f ? 4f transitions. Moreover, the Ce(3+) ion can transfer its energy to the Tb(3+) ion in the Ca2Ba3(PO4)3Cl host, and the energy transfer mechanism has been demonstrated to be a resonant type, via a dipole-quadrupole interaction. However, under the low voltage electron beam excitation, Tb(3+) ion doped Ca2Ba3(PO4)3Cl samples present different luminescence properties compared with their PL spectra, which is ascribed to the different excitation mechanism. On the basis of the good PL and CL properties of the Ca2Ba3(PO4)3Cl:A (A = Ce(3+)/Eu(2+)/Tb(3+)/Dy(3+)), Ca2Ba3(PO4)3Cl might be promising for application in solid state lighting and field-emission displays. PMID:23464598

  20. Solid-State Syntheses of Rare-Earth-Doped Sr1-xLn2x\\/3MgP2O7 (Ln = Gd, Eu, Dy, Sm, Pr, and Nd; x = 0.05) by Metathesis Reactions and their Spectroscopic Characterization

    Microsoft Academic Search

    Radha Velchuri; B. Vijaya Kumar; V. Rama Devi; D. Jaya Prakash; M. Vithal

    2011-01-01

    Rare-earth–doped strontium magnesium diphosphates of composition Sr1-xLn2x\\/3MgP2O7 (Ln = Gd, Eu, Dy, Sm, Pr, and Nd; x = 0.05) were prepared by metathesis reaction. These diphosphates were characterized by powder X-ray diffraction (XRD), energy dispersive spectra (EDS), and infrared spectroscopy. All these compounds were found to crystallize in monoclinic lattice with P21\\/n space group. The compositions of all the samples were confirmed from their

  1. The Dy-Ni-Si system as a representative of the rare earth-Ni-Si family: Its isothermal section and new rare-earth nickel silicides

    NASA Astrophysics Data System (ADS)

    Yuan, Fang; Mozharivskyj, Y.; Morozkin, A. V.; Knotko, A. V.; Yapaskurt, V. O.; Pani, M.; Provino, A.; Manfrinetti, P.

    2014-11-01

    The Dy-Ni-Si system has been investigated at 1070 K by X-ray and microprobe analysis. The system contains the 12 known compounds DyNi10Si2, DyNi5Si3, DyNi6Si6, DyNi4Si, DyNi2Si2, Dy2Ni3Si5, DyNiSi3, Dy3Ni6Si2, DyNiSi2, DyNiSi, Dy3NiSi3, Dy3NiSi2, and the new compounds Dy34Ni16-27Si50-39 (AlB2-type), Dy2Ni15.2-14.1Si1.8-2.9 (Th2Zn17-type), ~Dy11Ni65Si24, ~Dy16Ni62Si22 (unknown structures), DyNi7Si6 (GdNi7Si6-type), Dy3Ni8Si (Ce3Co8Si-type), DyNi2Si (YPd2Si-type), ~Dy40Ni47Si13 and ~Dy5Ni2Si3 (unknown structures). Quasi-binary solid solutions were detected at 1070 (870 K) for Dy2Ni17, DyNi5, DyNi7, DyNi3, DyNi2, DyNi, DySi2 and DySi1.67. No detectable solubility is observed for the other binary compounds of the Dy-Ni-Si system. The crystal structures of new phases RNi7Si6 (GdNi7Si6-type), R3Ni8Si (Ce3Co8Si-type), RNi2Si (YPd2Si-type) and R3Ni12Si4 (Gd3Ru4Al12-type), with R=Y, Gd-Tm, has been studied. Magnetic properties of few representative compounds are also reported. The crystal structures and magnetic properties of new phases RNi7Si6 (GdNi7Si6-type), R3Ni8Si (Ce3Co8Si-type), RNi2Si (YPd2Si-type) and R3Ni12Si4 (Gd3Ru4Al12-type), with R=Y, Gd-Tm, are also reported.

  2. Facile synthesis and luminescence properties of Y2O3:Ln(3+) (Ln(3+) = Eu(3+), Tb(3+), Dy(3+), Sm(3+), Er(3+), Ho(3+), Tm(3+), Yb(3+)/Er(3+), Yb(3+)/Tm(3+), Yb(3+)/Ho(3+)) microspheres.

    PubMed

    Xu, Zhenhe; Zhao, Qian; Ren, Baoyi; You, Lixin; Sun, Yaguang

    2014-08-01

    Multicolor and monodisperse Y2O3:Ln(3+) (Ln(3+) = Eu(3+), Tb(3+), Dy(3+), Sm(3+), Er(3+), Ho(3+), Tm(3+), Yb(3+)/Er(3+), Yb(3+)/Ho(3+)) microspheres were prepared through a facile urea-assisted homogeneous precipitation method followed by a subsequent calcination process. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectrum (EDS), Fourier transformed infrared (FT-IR), thermogravimetric analysis (TGA), photoluminescence (PL) and cathodoluminescence (CL) spectra were employed to characterize the samples. The XRD results reveal that the as-prepared spheres can be well indexed to cubic Y2O3 phase with high purity. The SEM and TEM images show the obtained Y2O3:Ln(3+) samples consist of regular nanospheres with the mean diameter of 350 nm. And the possible formation mechanism is also proposed. Upon ultraviolet and low-voltage electron beams excitation, Y2O3:Ln(3+) (Ln(3+) = Eu(3+), Tb(3+), Dy(3+), Sm(3+), Er(3+), Ho(3+), Tm(3+)) samples exhibit respective bright red (Eu(3+), (5)D0 --> (7)F2), green (Tb(3+), (5)D4 --> (7)F5), blue (Dy(3+), (4)F9/2 --> (6)H13/2), yellow (Sm(3+), (4)G5/2 --> (6)H7/2), green (Er(3+), (4)S3/2 --> (4)I15/2), green (Ho(3+), (5)S2 --> (5)I8), blue (Tm(3+), (1)D2 --> (3)F4) down-conversion (DC) emissions. Under 980 nm NIR irradiation, Y2O3:Ln(3+) (Ln(3+) = Yb(3+)/Er(3+), Yb(3+)/Tm(3+) and Yb(3+)/Ho(3+)) exhibit characteristic up-conversion (UC) emissions of green (Er(3+), (2)H11/2, (4)S3/2, (2)H11/2 --> (4)I5/2), blue (Tm(3+), (1)G4 --> (3)H6) and green (Ho(3+), (5)F4, (5)S2 --> (5)I8), respectively. These merits of multicolor emissions in the visible region endow this kind of material with potential applications in the field of light display systems, lasers, and optoelectronic devices. PMID:25936002

  3. Monte Carlo study on the imaging performance of powder Lu{sub 2}SiO{sub 5}:Ce phosphor screens under x-ray excitation: Comparison with Gd{sub 2}O{sub 2}S:Tb screens

    SciTech Connect

    Liaparinos, Panagiotis F.; Kandarakis, Ioannis S.; Cavouras, Dionisis A.; Delis, Harry B.; Panayiotakis, George S. [Department of Medical Physics, Faculty of Medicine, University of Patras, 265 00 Patras (Greece); Department of Medical Instruments Technology, Technological Educational Institute, 122 10 Athens (Greece); Department of Medical Physics, Faculty of Medicine, University of Patras, 265 00 Patras (Greece)

    2007-05-15

    Lu{sub 2}SiO{sub 5}:Ce (LSO) scintillator is a relatively new luminescent material which has been successfully applied in positron emission tomography systems. Since it has been recently commercially available in powder form, it could be of value to investigate its performance for use in x-ray projection imaging as both physical and scintillating properties indicate a promising material for such applications. In the present study, a custom and validated Monte Carlo simulation code was used in order to examine the performance of LSO, under diagnostic radiology (mammography and general radiography) conditions. The Monte Carlo code was based on a model using Mie scattering theory for the description of light attenuation. Imaging characteristics, related to image brightness, spatial resolution and noise of LSO screens were predicted using only physical parameters of the phosphor. The overall performance of LSO powder phosphor screens was investigated in terms of the: (i) quantum detection efficiency (ii) emitted K-characteristic radiation (iii) luminescence efficiency (iv) modulation transfer function (v) Swank factor and (vi) zero-frequency detective quantum efficiency [DQE(0)]. Results were compared to the traditional rare-earth Gd{sub 2}O{sub 2}S:Tb (GOS) phosphor material. The relative luminescence efficiency of LSO phosphor was found inferior to that of GOS. This is due to the lower intrinsic conversion efficiency of LSO (0.08 instead of 0.15 of GOS) and the relatively high light extinction coefficient m{sub ext} of this phosphor (0.239 {mu}m{sup -1} instead of 0.218 {mu}m{sup -1} for GOS). However, the property of increased light extinction combined with the rather sharp angular distribution of scattered light photons (anisotropy factor g=0.624 for LSO instead of 0.494 for GOS) reduce lateral light spreading and improve spatial resolution. In addition, LSO screens were found to exhibit better x-ray absorption as well as higher signal to noise transfer properties in the energy range from 18 keV up to 50.2 keV (e.g. DQE(0)=0.62 at 18 keV and for 34 mg/cm{sup 2}, instead of 0.58 for GOS). The results indicate that certain optical properties of LSO (optical extinction coefficient, scattering anisotropy factor) combined with the relatively high x-ray coefficients, make this material a promising phosphor which, under appropriate conditions, could be considered for use in x-ray projection imaging detectors.

  4. Magnetic and transport properties of i-R-Cd icosahedral quasicrystals (R=Y, Gd-Tm)

    SciTech Connect

    Kong, Tai [Ames Laboratory; Bud'ko, Sergey L. [Ames Laboratory; Jesche, Anton [Ames Laboratory; McArthur, John [Quantum Design Japan; Kreyssig, Andreas [Ames Laboratory; Goldman, Alan I. [Ames Laboratory; Canfield, Paul C. [Ames Laboratory

    2014-07-01

    We present a detailed characterization of the recently discovered i-R-Cd (R=Y,Gd-Tm) binary quasicrystals by means of x-ray diffraction, temperature-dependent dc and ac magnetization, temperature-dependent resistance, and temperature-dependent specific heat measurements. Structurally, the broadening of x-ray diffraction peaks found for i-R-Cd is dominated by frozen-in phason strain, which is essentially independent of R. i-Y-Cd is weakly diamagnetic and manifests a temperature-independent susceptibility. i-Gd-Cd can be characterized as a spin glass below 4.6 K via dc magnetization cusp, a third order nonlinear magnetic susceptibility peak, a frequency-dependent freezing temperature, and a broad maximum in the specific heat. i-R-Cd (R=Ho-Tm) is similar to i-Gd-Cd in terms of features observed in thermodynamic measurements. i-Tb-Cd and i-Dy-Cd do not show a clear cusp in their zero-field-cooled dc magnetization data, but instead show a more rounded, broad local maximum. The resistivity for i-R-Cd is of order 300?? cm and weakly temperature dependent. The characteristic freezing temperatures for i-R-Cd (R=Gd-Tm) deviate from the de Gennes scaling, in a manner consistent with crystal electric field splitting induced local moment anisotropy.

  5. Photoluminescence of Pr3+, Sm3+ and Dy3+: SiO2Al2O3-LiF-GdF3 glass ceramics and Sm3+, Dy3+: GeO2B2O3-ZnO-LaF3 glasses

    Microsoft Academic Search

    G. Lakshminarayana; Jianrong Qiu

    2009-01-01

    In this paper, we present the absorption and photoluminescence properties of Pr3+, Sm3+ and Dy3+-doped transparent oxyfluoride alumino-silicate glass ceramics and Sm3+ and Dy3+-doped oxyfluoride germanate glasses. The X-ray diffraction (XRD) and differential thermal analysis (DTA) profiles of these glasses have been carried out, to confirm their structure and thermal stability. These glasses or glass ceramics have shown strong emission

  6. Polarized Raman and IR spectra of oriented Cd0.9577Gd0.0282?0.0141MoO4 and Cd0.9346Dy0.0436?0.0218MoO4 single crystals where ? denotes the cationic vacancies

    NASA Astrophysics Data System (ADS)

    Macalik, L.; Tomaszewicz, E.; Ptak, M.; Hanuza, J.; Berkowski, M.; Ropuszynska-Robak, P.

    2015-09-01

    Polarized Fourier Transform IR and Raman spectra of Cd0.9577Gd0.0282?0.0141MoO4 and Cd0.9346Dy0.0436?0.0218MoO4 oriented single crystals have been recorded and analyzed using the factor group approach (? denotes the cationic vacancies). The tetragonal I41/a (C4h6) space group with Z = 2 has been applied in the discussion. The influence of the structural changes induced by the defects in the CdMoO4 host lattice on the vibrational symmetry rules has been analyzed. The assignment of the observed bands to the internal and external modes has been proposed.

  7. Polarized Raman and IR spectra of oriented Cd0.9577Gd0.0282?0.0141MoO4 and Cd0.9346Dy0.0436?0.0218MoO4 single crystals where ? denotes the cationic vacancies.

    PubMed

    Macalik, L; Tomaszewicz, E; Ptak, M; Hanuza, J; Berkowski, M; Ropuszynska-Robak, P

    2015-09-01

    Polarized Fourier Transform IR and Raman spectra of Cd0.9577Gd0.0282?0.0141MoO4 and Cd0.9346Dy0.0436?0.0218MoO4 oriented single crystals have been recorded and analyzed using the factor group approach (? denotes the cationic vacancies). The tetragonal I41/a (C4h(6)) space group with Z=2 has been applied in the discussion. The influence of the structural changes induced by the defects in the CdMoO4 host lattice on the vibrational symmetry rules has been analyzed. The assignment of the observed bands to the internal and external modes has been proposed. PMID:25897720

  8. Synthesis and VUV-UV spectroscopic properties of rare earth borosilicate oxyapatite: RE âSiâBOââ:Ln {sup 3+} (RE=La, Gd, Y; Ln=Eu, Tb)

    Microsoft Academic Search

    Yuan Junlin; Zhang Zhijun; Wang Xiaojun; Chen Haohong; Zhao Jingtai; Zhang Guobin; Shi Chaoshu

    2007-01-01

    Three rare earth borosilicate oxyapatites, RE âSiâBOââ (RE=La, Gd, Y), were synthesized via wet chemical method, of which RE âSiâBOââ (RE=Gd, Y) were first reported in this work. In the three oxyapatites, [BOâ] and [SiOâ] share the [TOâ] tetrahedral oxyanion site, and RE {sup 3+} ions occupy all metal sites. The differential scanning calorimetry-thermo gravimetry measurements and high temperature powder

  9. The VUV-vis spectroscopic properties of phosphors CaâGd{sub 2(1-x)}Ln{sub 2x}(BOâ)â (Ln{sup 3+} = Ce, Sm, Eu, Tb)

    Microsoft Academic Search

    Liang Hongbin; Su Qiang; Tao Ye; Xu Jianhua; Huang Yan

    2006-01-01

    The spectroscopic properties in VUV-vis range for phosphors calcium and gadolinium double borate CaâGdâ(BOâ)â doped with rare-earth ions Ce{sup 3+}, Sm{sup 3+}, Eu{sup 3+} and Tb{sup 3+} were investigated. The host-related absorption, the f-d transitions of Ce{sup 3+} and Tb{sup 3+}, as well as the charge transfer transitions of Sm{sup 3+} and Eu{sup 3+} in the host lattice are assigned

  10. Synthesis and VUV–UV spectroscopic properties of rare earth borosilicate oxyapatite: RE 5Si 2BO 13: Ln 3+ ( RE=La, Gd, Y; Ln=Eu, Tb)

    Microsoft Academic Search

    Jun-Lin Yuan; Zhi-Jun Zhang; Xiao-Jun Wang; Hao-Hong Chen; Jing-Tai Zhao; Guo-Bin Zhang; Chao-Shu Shi

    2007-01-01

    Three rare earth borosilicate oxyapatites, RE5Si2BO13 (RE=La, Gd, Y), were synthesized via wet chemical method, of which RE5Si2BO13 (RE=Gd, Y) were first reported in this work. In the three oxyapatites, [BO4] and [SiO4] share the [TO4] tetrahedral oxyanion site, and RE3+ ions occupy all metal sites. The differential scanning calorimetry–thermo gravimetry measurements and high temperature powder X-ray diffraction pattern revealed

  11. A series of tetranuclear lanthanide complexes comprising two edge-sharing triangular units with field-induced slow magnetic relaxation for Dy4 species.

    PubMed

    Xue, Shufang; Zhao, Lang; Guo, Yun-Nan; Deng, Ruiping; Guo, Yang; Tang, Jinkui

    2011-09-01

    The syntheses, crystal structures and magnetic studies are reported for a series of Ln(4) clusters formulated as Ln(4)(?(3)-OH)(2)(php)(2)(OAc)(6)(H(2)O)(2)]·4MeOH·nH(2)O (Ln = Gd (1), Tb (2), Dy (3) (n = 2) and Ho (4) (n = 0); H(2)php = 2,6-(picolinoylhydrazone)pyridine). The overall metal core of each cluster is comprised of two edge-sharing triangular Ln(3) units linked by ?(3)-OH bridges. Direct-current (dc) magnetic susceptibility studies reveal that the Ln(III) ions are very weakly coupled in all four compounds. Alternating-current (ac) magnetic susceptibility studies for 3 indicate that field-induced slow relaxation phenomenon occurs for this compound. PMID:21789321

  12. New structural form of a tetranuclear lanthanide hydroxo cluster: Dy4 analogue display slow magnetic relaxation.

    PubMed

    Jami, Ananda Kumar; Baskar, Viswanathan; Sañudo, E Carolina

    2013-03-01

    A series of tetranuclear lanthanide (Ln = Tb, Dy, Ho) hydroxo clusters has been synthesized by reaction of LnCl3·6H2O (Ln = Tb (1), Dy (2), Ho (3)) with o-vanilin based schiff base ligand 2-(2,3 dihydroxpropyl imino methyl) 6-methoxy phenol (H3L) in methanol and in the presence of triethylamine as base. The solid state structures of all the products were established by single crystal X-ray diffraction technique. Magnetism studies reveal that Dy4 analogue exhibits slow magnetic relaxation at low temperatures. PMID:23428076

  13. Eu{sup 3+} luminescence in La{sub 5}Si{sub 2}BO{sub 13} with apatite related structure and magnetic studies in Ln{sub 5}Si{sub 2}BO{sub 13} (Ln=Gd, Dy)

    SciTech Connect

    Asiri Naidu, S. [Materials Science Research Centre, Indian Institute of Technology Madras, Chennai 600036 (India); Varadaraju, U.V., E-mail: varada@iitm.ac.i [Materials Science Research Centre, Indian Institute of Technology Madras, Chennai 600036 (India); Raveau, B. [Laboratoire de Crystallographie et Sciences des Materiaux, ENSICAEN, UniVersite de Caen, CNRS, 6 Bd Marechal Juin, F-14050 Caen 4 (France)

    2010-08-15

    Eu{sup 3+} photoluminescence is studied in La{sub 5}Si{sub 2}BO{sub 13} with apatite related structure. La{sub 5-x}Eu{sub x}Si{sub 2}BO{sub 13} [x=0.05, 0.1, 0.3, 0.5, 0.7, 1.0, 2.0] compositions are synthesized. The emission results shows that Eu{sup 3+} ions occupy two different cationic sites viz., La(1) and La(2). The increase in the intensity of {sup 5}D{sub 0}-{sup 7}F{sub 0} line with increasing Eu{sup 3+} content shows the preferential occupancy of Eu{sup 3+} in La(2) site due to the existence of short La(2)-O(4) (free oxide ion) bond. The observation of antiferromagnetic interactions in Gd and Dy analogues supports the structural features elucidates from photoluminescence studies. - Graphical abstract: In La{sub 5}Si{sub 2}BO{sub 13}, the La(1)O{sub 9} polyhedra share faces, the La(2)O{sub 7} polyhedra are connected through corners and La(2)O{sub 7} and La(1)O{sub 9} polyhedra are connected to each other by edge sharing along 'z'-axis.

  14. Enhancement of optical Faraday effect of nonanuclear Tb(III) complexes.

    PubMed

    Nakanishi, Takayuki; Suzuki, Yuki; Doi, Yoshihiro; Seki, Tomohiro; Koizumi, Hitoshi; Fushimi, Koji; Fujita, Koji; Hinatsu, Yukio; Ito, Hajime; Tanaka, Katsuhisa; Hasegawa, Yasuchika

    2014-07-21

    The effective magneto-optical properties of novel nonanuclear Tb(III) complexes with Tb-O lattice (specifically, [Tb9(sal-R)16(?-OH)10](+)NO3(-), where sal-R = alkyl salicylate (R = -CH3 (Me), -C2H5 (Et), -C3H7 (Pr), or -C4H9 (Bu)) are reported. The geometrical structures of these nonanuclear Tb(III) complexes were characterized using X-ray single-crystal analysis and shape-measure calculation. Optical Faraday rotation was observed in nonanuclear Tb(III) complexes in the visible region. The Verdet constant per Tb(III) ion of the Tb9(sal-Me) complex is 150 times larger than that of general Tb(III) oxide glass. To understand their large Faraday rotation, electron paramagnetic resonance measurements of Gd(III) complexes were carried out. In this Report, the magneto-optical relation to the coordination geometry of Tb ions is discussed. PMID:24956446

  15. Magnetic Properties of Dy in Pb

    SciTech Connect

    Skanthakumar, S.; Soderholm, L.; Movshovich, R.

    1999-07-10

    Superconductivity can be induced at high temperatures in Pb{sub 2}Sr{sub 2}RCu{sub 3}O{sub 8} (R - rare earth) by partially doping Ca{sup 2+} for R{sup 3+}. In order to understand the interplay between magnetism and superconductivity, the magnetic properties of the parent compounds, Pb{sub 2}Sr{sub 2}RCu{sub 3}O{sub 8}, have been studied. The work presented here includes magnetic susceptibility and specific heat measurements on R=Dy and extends the previous studies on R=Ce, Pr, Tb, Ho and Er. Specific heat experiments suggest that the Dy ions order antiferromagnetically with an ordering temperature of 1.3K. The magnetic susceptibility data are in good agreement with the susceptibility calculated using crystal field parameters that are extrapolated from previous modeling of the R=Er and Ho analogs of this series.

  16. Raman spectra of 2Ln/sub 2/O/sub 3/ /times/ 9TiO/sub 2/ compounds (Ln = Ce, La, Nd, Pr, Sm, Eu, Gd, Tm, Yb, Tb)

    SciTech Connect

    Mel'nik, N.N.; Tsapenko, L.M.

    1988-03-01

    This work uses Raman and x-ray phase analysis methods to investigate compounds of the type 2Ln/sub 2/O/sub 3/ /times/ 9TiO/sub 2/ (where Ln = Ce, La, Nd, Pr, Sm, Eu, Gd, Tm, and Yb). The compounds were synthesized by melting in an optical beam on a water-cooled substrate (quench rate approx. 10/sup 2/ deg/sec) and by rapid quenching of a melt cupel by slamming with water-cooled blocks quench rate approx. 10/sup 5/ - 10/sup 6/ deg/sec. The x-ray diffraction study was done on a DRON-2 diffractometer. The Raman light spectra were recorded with a DFS-24 double monochromator employing argon laser excitation.

  17. Synthesis and morphology of Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals with tungsten bronze structure in RE{sub 2}O{sub 3}-BaO-Nb{sub 2}O{sub 5}-B{sub 2}O{sub 3} glasses (RE: Sm, Eu, Gd, Dy, Er)

    SciTech Connect

    Ida, H.; Shinozaki, K.; Honma, T.; Oh-ishi, K. [Department of Materials Science and Technology, Nagaoka University of Technology, 1603-1 Kamitomioka-cho, Nagaoka 940-2188 (Japan)] [Department of Materials Science and Technology, Nagaoka University of Technology, 1603-1 Kamitomioka-cho, Nagaoka 940-2188 (Japan); Komatsu, T., E-mail: komatsu@mst.nagaokaut.ac.jp [Department of Materials Science and Technology, Nagaoka University of Technology, 1603-1 Kamitomioka-cho, Nagaoka 940-2188 (Japan)

    2012-12-15

    Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals with a tetragonal tungsten bronze (TTB) structure are synthesized using a conventional glass crystallization technique in 2.3RE{sub 2}O{sub 3}-27.4BaO-34.3Nb{sub 2}O{sub 5}-36B{sub 2}O{sub 3} (mol%) (RE=Sm, Eu, Gd, Dy, and Er) glasses. One sharp crystallization peak is observed at {approx}670 Degree-Sign C in both powdered and bulk glasses, and the formation of Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals with unit cell parameters of a{approx}1.24 nm and c{approx}0.39 nm was confirmed. It is found from high resolution transmission electron microscope observations that the morphology of Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals is ellipsoidal. Their average particle size is in the range of 15-60 nm and decreases with decreasing ionic radius of RE{sup 3+} being present in the precursor glasses. The optical transparent crystallized glass (bulk) shows the total photoluminescence (PL) quantum yield of 53% in the visible region of Eu{sup 3+} ions, suggesting a high potential of Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals as PL materials. - Graphical abstract: This figure shows a TEM photograph for the heat-treated (667 Degree-Sign C, 3 h) sample of 2.3Dy{sub 2}O{sub 3}-27.4BaO-34.3Nb{sub 2}O{sub 5}-36B{sub 2}O{sub 3}. An ellipsoidal-shaped Ba{sub 1-x}Dy{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystal with diameters of 17 and 28 nm is observed. The ellipsoidal morphology is a common feature in Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals synthesized by the crystallization of 2.3RE{sub 2}O{sub 3}-27.4BaO-34.3Nb{sub 2}O{sub 5}-36B{sub 2}O{sub 3} glasses. Highlights: Black-Right-Pointing-Pointer Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals with a tetragonal tungsten bronze structure are synthesized. Black-Right-Pointing-Pointer A glass crystallization technique was applied. Black-Right-Pointing-Pointer The morphology of Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals is ellipsoidal. Black-Right-Pointing-Pointer The average particle size with 15-60 nm decreases with decreasing ionic radius of RE{sup 3+}. Black-Right-Pointing-Pointer Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals have a high potential as photoluminescence materials.

  18. New tetragonal derivatives of cubic NaZn{sub 13}-type structure: RNi{sub 6}Si{sub 6} compounds, crystal structure and magnetic ordering (R=Y, La, Ce, Sm, Gd–Yb)

    SciTech Connect

    Pani, M.; Manfrinetti, P.; Provino, A. [INFM and Dipartimento di Chimica e Chimica Industriale, Universita‘ di Genova, Via Dodecaneso 31, 16146 Genova (Italy); Yuan, Fang; Mozharivskyj, Y. [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, ON, Canada L8S 4M1 (Canada); Morozkin, A.V., E-mail: morozkin@general.chem.msu.ru [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Knotko, A.V.; Garshev, A.V. [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Yapaskurt, V.O. [Department of Petrology, Geological Faculty, Moscow State University, Leninskie Gory, Moscow 119992 (Russian Federation); Isnard, O. [Université Grenoble Alpes, Inst NEEL, BP166, F-38042 Grenoble (France); CNRS, Institut NEEL, 25 rue des martyrs, F-38042 Grenoble (France)

    2014-02-15

    Novel RNi{sub 6}Si{sub 6} compounds adopt the new CeNi{sub 6}Si{sub 6}-type structure for R=La–Ce (tP52, space group P4/nbm N 125-1) and new YNi{sub 6}Si{sub 6}-type structure for R=Y, Sm, Gd–Yb (tP52, space group P4{sup ¯}b2N 117) that are tetragonal derivative of NaZn{sub 13}-type structure, like LaCo{sub 9}Si{sub 4}-type. The CeNi{sub 6}Si{sub 6}, GdNi{sub 6}Si{sub 6}, TbNi{sub 6}Si{sub 6}, DyNi{sub 6}Si{sub 6} and HoNi{sub 6}Si{sub 6} compounds are Curie–Weiss paramagnets down to ?30 K, and do not order magnetically down to 5 K. However, the inverse paramagnetic susceptibility of LaNi{sub 6}Si{sub 6} does not follow Curie–Weiss law. The DyNi{sub 6}Si{sub 6} shows ferromagnetic-like saturation behaviour at 5 K in applied fields of 50 kOe, giving rise to a magnetic moment value of 6.5 ?{sub B}/f.u. in 50 kOe. The powder neutron diffraction study in zero applied filed indicates square modulated the c-collinear antiferromagnetic ordering of TbNi{sub 6}Si{sub 6} with K=[±1/4, ±1/4, 0] wave vector below ?10 K. - Graphical abstract: Novel (La, Ce)Ni{sub 6}Si{sub 6} compounds adopt the new CeNi{sub 6}Si{sub 6}-type structure and (Y, Sm, Gd–Yb) adopt the new YNi{sub 6}Si{sub 6}-type structure that are tetragonal derivative of NaZn{sub 13}-type structure, like LaCo{sub 9}Si{sub 4}-type. The CeNi{sub 6}Si{sub 6}, GdNi{sub 6}Si{sub 6}, TbNi{sub 6}Si{sub 6}, DyNi{sub 6}Si{sub 6} and HoNi{sub 6}Si{sub 6} compounds are Curie–Weiss paramagnets down to ?30 K, and do not order magnetically down to 4.2 K. The powder neutron diffraction study in zero applied filed indicates square modulated the c-collinear antiferromagnetic ordering of TbNi{sub 6}Si{sub 6} with K=[±1/4, ±1/4, 0] wave vector below ?10 K. Display Omitted - Highlights: • The new (La, Ce)Ni{sub 6}Si{sub 6} compounds adopt the new CeNi{sub 6}Si{sub 6}-type structure. • The new (Y, Sm, Gd–Yb)Ni{sub 6}Si{sub 6} compounds adopt the new YNi{sub 6}Si{sub 6}-type structure. • TbNi{sub 6}Si{sub 6} has square modulated c-collinear antiferromagnetic ordering below ?10 K.

  19. Luminescence study on Eu or Tb doped lanthanum-gadolinium pyrosilicate crystal

    NASA Astrophysics Data System (ADS)

    Kurosawa, Shunsuke; Shishido, Toetsu; Sugawara, Takamasa; Nomura, Akiko; Yubuta, Kunio; Pejchal, Jan; Murakami, Rikito; Yokota, Yuui; Shoji, Yasuhiro; Ohashi, Yuji; Kamada, Kei; Yoshikawa, Akira

    2015-03-01

    (Eu0.01, Gd0.90, La0.09)2Si2O7 (Eu:La-GPS) and (Tb0.01, Gd0.90, La0.09)2Si2O7 (Tb:La-GPS) crystals were grown by the floating zone method, and their optical and scintillation properties were investigated. Gd3+-to-Tb3+ or -Eu3+ energy transfer processes were found, and photo-luminescence and radio-luminescence emission spectra showed 5D0-7Fi (i = 1-4) Eu3+ transitions in Eu:La-GPS, and 5D3-7Fi (i = 3-6) and 5D4-7Fi (i = 3-6) transitions in Tb:La-GPS. Using these scintillators, alpha-ray imaging was possible with a CMOS camera. These materials can be used for X-ray detection as well.

  20. Hyperfine interaction of 161 Dy imprities implated in iron and nickel

    Microsoft Academic Search

    H. P. Wit; L. Niesen; H. De Waard

    1977-01-01

    In this paper we present a full report on our Mössbauer measurements on implanted sources of161TbFe and161TbNi using the 26.7 keV Mössbauer transition in161Dy. From the measured spectra values were derived for the magnetic and quadrupole interaction strengths of rare earth ions in at least two non-equivalent lattice sites and information is obtained about the relaxation behaviour of these ions.

  1. A second ferroelectric transition induced by pressure in multiferroic GdMn2O5

    NASA Astrophysics Data System (ADS)

    Lorenz, Bernd; Poudel, Narayan; Gooch, Melissa; Chu, Ching-Wu; Cheong, Sang-Wook

    2015-03-01

    In multiferroic materials different magnetic and ferroelectric states compete for the ground state and are usually close in energy. This results in a high sensitivity of the multiferroic state to external perturbations, such as magnetic fields or pressure, which has been demonstrated, e.g. in Ni3V2O8,MnWO4,andRMn2O5 (R = Tb, Ho, Dy, Y). Here we report the results of a high-pressure study of the multiferroic and ferroelectric properties of GdMn2O5,theRMn2O5 compound with the highest value of the polarization. The ferroelectric polarization below 29 K is enhanced upon application of pressure. Above a critical pressure, a second ferroelectric transition at even higher temperature is detected through a sizable increase of the polarization and a second peak of the dielectric constant. The ferroelectric polarization at high pressures exhibits two step-like increases upon decreasing temperature. This work was supported by the US AFOSR, the T.L.L. Temple Foundation, the John J. and Rebecca Moores Endowment, and the State of Texas through TCSUH.

  2. Strongly correlated electron behavior : superconductivity and non-Fermi liquid behavior in Ce?-xRxColn?

    E-print Network

    Gonzales, Eileen

    2009-01-01

    Tb, Dy, Yb) vs. Rare earth Elements R . . . 43 viii FigureGd, TB, Dy, Yb) vs. Rare earth Elements R as derived fromrare earth’s (Praseodymium, Neodymium, Dysprosium, Table II.1: Melting temperatures, supplier, and purities of elements

  3. High-spin states in {sup 152}Gd

    SciTech Connect

    Wang, S.; Hua, H.; Meng, J.; Li, Z.H.; Zhang, S.Q.; Xu, F.R.; Liu, H.L.; Ye, Y.L.; Jiang, D.X.; Zheng, T.; Wang, Q.J.; Chen, Z.Q.; Wu, C.E.; Zhang, G.L.; Pang, D.Y.; Wang, J.; Lou, J.L.; Guo, B.; Jin, G.; Zhou, S.G. [School of Physics and MOE Key Laboratory of Heavy Ion Physics, Peking University, Beijing 100871 (China); Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100080, China and Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator, Lanzhou 730000 (China); China Institute of Atomic Energy, Beijing 102413 (China)] [and others

    2005-08-01

    High-spin states of {sup 152}Gd have been studied via the {sup 148}Nd({sup 9}Be,5n){sup 152}Gd fusion-evaporation reaction at a beam energy of 54 MeV. The ground-state band, octupole band, and {beta} band have been extended up to spins 20{sup +}, 21{sup -}, and 16{sup +}, respectively. A possible aligned two quasineutron band, which becomes the yrast band above the spin 16{sup +}, was observed for the first time. The kinematic behaviors of the ground-state bands and yrast bands in {sup 152,154}Gd indicate that the shape of {sup 152}Gd may change with increasing rotational frequency and the difference of quadrupole deformations between {sup 152}Gd and {sup 154}Gd obviously reduces around the first band crossing region. These observations are consistent with the theoretical calculations using cranked Woods-Saxon-Strutinsky methods. The first band crossing observed in {sup 152}Gd can be ascribed to the alignment of a pair of i{sub 13/2} neutrons. The identical ground-state bands in {sup 152}Gd and {sup 154}Dy were extended.

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

    NASA Astrophysics Data System (ADS)

    Mioduski, Tomasz; Gumi?ski, Cezary; Zeng, Dewen

    2015-06-01

    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 TbF4 and YbF2 (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.

  5. Squaring the cube: a family of octametallic lanthanide complexes including a Dy8 single-molecule magnet.

    PubMed

    Fang, Ming; Zhao, Hanhua; Prosvirin, Andrey V; Pinkowicz, Dawid; Zhao, Bin; Cheng, Peng; Wernsdorfer, Wolfgang; Brechin, Euan K; Dunbar, Kim R

    2013-10-01

    A series of isostructural octanuclear lanthanide complexes of general formula [Ln8(sao)4(?3-OH)4(NO3)12(DMF)12] (Ln = Nd (), Sm (), Eu (), Gd (), Tb (), Dy (), Ho (), Er (); DMF = dimethylformamide) have been prepared via reactions of salicylaldoxime (saoH2), tetramethylammonium hydroxide (Me4NOH) with the appropriate lanthanide nitrate salt (Ln(NO3)3·6H2O). The metallic skeletons of the complexes describe [Ln4] tetrahedra encapsulated inside a [Ln4] square with the inner core stabilised through ?3-OH(-) ions and the periphery by ?4-sao(2-) ligands. The magnetic properties of compounds were investigated by dc and ac magnetometry. Temperature dependent ac magnetic susceptibility data reveal that the dysprosium analogue () displays an out-of-phase signal in the absence of an applied magnetic field indicative of slow relaxation of the magnetization typical of a Single-Molecule Magnet (SMM). Micro-SQUID measurements reveal temperature and sweep rate dependent hysteresis below 1.0 K. PMID:23943045

  6. Bose-Einstein condensation of 162Dy and 160Dy

    E-print Network

    Yijun Tang; Nathaniel Q. Burdick; Kristian Baumann; Benjamin L. Lev

    2014-11-12

    We report Bose-Einstein condensation of two isotopes of the highly magnetic element dysprosium: 162Dy and 160Dy. For 162Dy, condensates with 10^5 atoms form below T = 50 nK. We find the evaporation efficiency for the isotope 160Dy to be poor; however, by utilizing a low-field Fano-Feshbach resonance to carefully change the scattering properties, it is possible to produce a Bose-Einstein condensate of 160Dy with 10^3 atoms. The 162Dy BEC reported is an order of magnitude larger in atom number than that of the previously reported 164Dy BEC, and it may be produced within 18 s.

  7. Slow magnetic relaxation and field-induced metamagnetism in nitronyl nitroxide-Dy(III) magnetic chains.

    PubMed

    Wang, Xiufeng; Li, Yungai; Hu, Peng; Wang, Juanjuan; Li, Licun

    2015-03-14

    The combination of lanthanide ions and nitronyl nitroxide radicals resulted in four new Ln-radical one-dimensional compounds, namely, [Ln(hfac)3{NIT-Ph(OMe)2}]n(Ln(III) = Sm (1), Eu (2), Gd (3), Dy (4); hfac = hexafluoroacetylacetonate; NIT-Ph(OMe)2 = 2-(2',4'-dimethoxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl-3-oxide). The four complexes were found to be isomorphous and exhibit nitronyl nitroxide radicals-bridged lanthanides linear chains. DC magnetic susceptibilities show that the directly bonded nitronyl nitroxide interacts ferromagnetically with Gd and Dy ions. The Dy complex exhibits three-step metamagnetism and frequency-dependent ac magnetic susceptibilities, indicating single-chain magnet behavior. This work shows that the magnetic behaviors of one-dimensional Ln-nitronyl nitroxide chains can be fine tuned by the substituents of the radicals. PMID:25652849

  8. Series of edge-sharing bi-triangle Ln4 clusters with a ?4-NO3- bridge: syntheses, structures, luminescence, and the SMM behavior of the Dy4 analogue.

    PubMed

    Zou, Hua-Hong; Wang, Rong; Chen, Zi-Lu; Liu, Dong-Cheng; Liang, Fu-Pei

    2014-02-14

    A series of Ln4 clusters, [Ln4L2(?3-OH)2(?4-NO3)(NO3)4(OCH3)(H2O)]·xMeCN·yMeOH (Ln = Gd (1), Tb (2), Dy (3), Ho (4), Er (5), Yb (6), L = 2-{[2-(2-hydroxy-ethoxy)-ethylimino]-methyl}-6-methoxyphenol), have been synthesized by the reaction of Ln(NO)3 and a Schiff-base ligand formed in situ. The six complexes display similar structures, with an overall metal core comprising two edge-sharing triangular Ln3 units linked by a ?4-NO3(-) bridge. The luminescence spectrum of complex 2 shows the characteristic emission of the Tb(III) ions. The magnetic susceptibility studies reveal that the Ln(III) ions are very weakly interacting in all six compounds. Frequency dependence of the ac-susceptibility was found for 3, suggesting a typical single-molecule magnet (SMM) behavior with an anisotropic barrier of 28 K. PMID:24316728

  9. Synthesis, structure, and thermally stable luminescence of Eu(2+)-doped Ba2Ln(BO3)2Cl (Ln = Y, Gd and Lu) host compounds.

    PubMed

    Xia, Zhiguo; Wang, Xiaoming; Wang, Yingxia; Liao, Libing; Jing, Xiping

    2011-10-17

    A new family of chloroborate compounds, which was investigated from the viewpoint of rare earth ion activated phosphor materials, have been synthesized by a conventional high temperature solid-state reaction. The crystal structure and thermally stable luminescence of chloroborate phosphors Ba(2)Ln(BO(3))(2)Cl:Eu(2+) (Ln = Y, Gd, and Lu) have been reported in this paper. X-ray diffraction studies verify the successful isomorphic substitution for Ln(3+) sites in Ba(2)Ln(BO(3))(2)Cl by other smaller trivalent rare earth ions, such as Sm, Eu, Tb, Dy, Ho, Er, Tm, and Yb. The detailed structure information for Ba(2)Ln(BO(3))(2)Cl (Ln = Y, Gd, and Lu) by Rietveld analysis reveals that they all crystallize in a monoclinic P2(1)/m space group. These compounds display interesting and tunable photoluminescence (PL) properties after Eu(2+)-doping. Ba(2)Ln(BO(3))(2)Cl:Eu(2+) phosphors exhibit bluish-green/greenish-yellow light with peak wavelengths at 526, 548, and 511 nm under 365 UV light excitation for Ba(2)Y(BO(3))(2)Cl:Eu(2+), Ba(2)Gd(BO(3))(2)Cl:Eu(2+), and Ba(2)Lu(BO(3))(2)Cl:Eu(2+), respectively. Furthermore, they possess a high thermal quenching temperature. With the increase of temperature, the emission bands show blue shifts with broadening bandwidths and slightly decreasing emission intensities. It is expected that this series of chloroborate phosphors can be used in white-light UV-LEDs as a good wavelength-conversion phosphor. PMID:21919480

  10. Fusion of $^{6}$Li with $^{159}$Tb} at near barrier energies

    E-print Network

    M. K. Pradhan; A. Mukherjee; P. Basu; A. Goswami; R. Kshetri; R. Palit; V. V. Parkar; M. Ray; Subinit Roy; P. Roy Chowdhury; M. Saha Sarkar; S. Santra

    2011-06-10

    Complete and incomplete fusion cross sections for $^{6}$Li+$^{159}$Tb have been measured at energies around the Coulomb barrier by the $\\gamma$-ray method. The measurements show that the complete fusion cross sections at above-barrier energies are suppressed by $\\sim$34% compared to the coupled channels calculations. A comparison of the complete fusion cross sections at above-barrier energies with the existing data of $^{11,10}$B+$^{159}$Tb and $^{7}$Li+$^{159}$Tb shows that the extent of suppression is correlated with the $\\alpha$-separation energies of the projectiles. It has been argued that the Dy isotopes produced in the reaction $^{6}$Li+$^{159}$Tb, at below-barrier energies are primarily due to the $d$-transfer to unbound states of $^{159}$Tb, while both transfer and incomplete fusion processes contribute at above-barrier energies.

  11. Ternary rare-earth ruthenium and iridium germanides RE{sub 3}M{sub 2}Ge{sub 3} (RE=Y, Gd–Tm, Lu; M=Ru, Ir)

    SciTech Connect

    Oliynyk, Anton O.; Stoyko, Stanislav S.; Mar, Arthur, E-mail: arthur.mar@ualberta.ca

    2013-06-15

    Through arc-melting reactions of the elements and annealing at 800 °C, the ternary rare-earth germanides RE{sub 3}Ru{sub 2}Ge{sub 3} and RE{sub 3}Ir{sub 2}Ge{sub 3} have been prepared for most of the smaller RE components (RE=Y, Gd–Tm, Lu). In the iridium-containing reactions, the new phases RE{sub 2}IrGe{sub 2} were also generally formed as by-products. Powder X-ray diffraction revealed orthorhombic Hf{sub 3}Ni{sub 2}Si{sub 3}-type structures (space group Cmcm, Z=4) for RE{sub 3}M{sub 2}Ge{sub 3} (M=Ru, Ir) and monoclinic Sc{sub 2}CoSi{sub 2}-type structures (space group C2/m, Z=4) for RE{sub 2}IrGe{sub 2}. Full crystal structures were determined by single-crystal X-ray diffraction for all members of RE{sub 3}Ru{sub 2}Ge{sub 3} (a=4.2477(6) Å, b=10.7672(16) Å, c=13.894(2) Å for RE=Y; a=4.2610(3)–4.2045(8) Å, b=10.9103(8)–10.561(2) Å, c=14.0263(10)–13.639(3) Å in the progression of RE from Gd to Lu) and for Tb{sub 3}Ir{sub 2}Ge{sub 3} (a=4.2937(3) Å, b=10.4868(7) Å, c=14.2373(10) Å). Both structures can be described in terms of CrB- and ThCr{sub 2}Si{sub 2}-type slabs built from Ge-centred trigonal prisms. However, band structure calculations on Y{sub 3}Ru{sub 2}Ge{sub 3} support an alternative description for RE{sub 3}M{sub 2}Ge{sub 3} based on [M{sub 2}Ge{sub 3}] layers built from linked MGe{sub 4} tetrahedra, which emphasizes the strong M–Ge covalent bonds present. The temperature dependence of the electrical resistivity of RE{sub 3}Ru{sub 2}Ge{sub 3} generally indicates metallic behaviour but with low-temperature transitions visible for some members (RE=Gd, Tb, Dy) that are probably associated with magnetic ordering of the RE atoms. Anomalously, Y{sub 3}Ru{sub 2}Ge{sub 3} exhibits semiconductor-like behaviour of uncertain origin. Magnetic measurements on Dy{sub 3}Ru{sub 2}Ge{sub 3} reveal antiferromagnetic ordering at 3 K and several unusual field-dependent transitions suggestive of complex spin reorientation processes. - Graphical abstract: RE{sub 3}M{sub 2}Ge{sub 3} (M=Ru, Ir) adopts the Hf{sub 3}Ni{sub 2}Si{sub 3}-type structure containing slabs built up from Ge-centred trigonal prisms. - Highlights: • Crystal structures of RE{sub 3}Ru{sub 2}Ge{sub 3} (RE=Y, Gd–Tm, Lu) and Tb{sub 3}Ir{sub 2}Ge{sub 3} were determined. • Strong M–Ge covalent bonds were confirmed by band structure calculations. • Most RE{sub 3}Ru{sub 2}Ge{sub 3} members except Y{sub 3}Ru{sub 2}Ge{sub 3} exhibit metallic behaviour. • Dy{sub 3}Ru{sub 2}Ge{sub 3} displays unusual field-dependent magnetic transitions.

  12. Structural modulations in the rare-earth metal digermanides REAl1-xGe2 (RE = Gd-Tm, Lu, Y; 0.8 < x < 0.9). Correlations between long- and short-range vacancy ordering.

    PubMed

    Zhang, Jiliang; Wang, Yingmin; Bobev, Svilen

    2015-02-01

    Rare-earth metal aluminum germanides with the general formula REAl(1-x)Ge(2) (RE = Gd, Tb, Dy, Ho, Er, Tm, Lu, and Y) have been synthesized by direct fusion of the corresponding elements. The structures have been studied by single-crystal X-ray diffraction and selected-area electron diffraction (SAED). The average structure represents a randomly "stuffed" variant of the orthorhombic ZrSi(2) structure type, also known as the CeNi(1-x)Si(2) type (Pearson symbol oC16; space group Cmcm). The SAED patterns for selected members of the family suggest the coexistence of commensurate and incommensurate structural modulations. The most prominent model for long-range vacancy ordering is the Tb(4)FeGe(8) type (Pearson symbol mP26; space group P21/n), which is the commensurate 4-fold superstructure of CeNi(1-x)Si(2) (x = (3)/4). Short-range correlations cause additional deviations in the 4-fold superlattice. These results shed more light on the structural complexity as a function of the aluminum vacancies and size of the rare-earth metal. Magnetic susceptibility measurements are presented and discussed. The measured ordering temperatures and calculated ones based on empirical rules and Ruderman-Kittel-Kasuya-Yosida interactions are shown to be in close agreement. PMID:24964140

  13. Structural origin for the local strong anisotropy in melt-spun Fe-Ga-Tb: Tetragonal nanoparticles

    NASA Astrophysics Data System (ADS)

    Ma, Tianyu; Hu, Shanshan; Bai, Guohua; Yan, Mi; Lu, Yunhao; Li, Huiying; Peng, Xiaoling; Ren, Xiaobing

    2015-03-01

    Soluting rare earth atoms Tb or Dy into body centered cubic (BCC) Fe-Ga through rapid cooling significantly enhances the magnetostriction due to strong localized magnetocrystalline anisotropy. Origin of the local strong anisotropy, however, awaits comprehensive microstructural investigation. In this letter, formation of tetragonal nanoparticles with c/a ˜ 0.979 has been found in the giant magnetostrictive ribbons Fe82.89Ga16.88Tb0.23 due to local symmetry breaking of the BCC lattice using high resolution transmission electronic microscopy. First principal calculations suggest that random replacement of Tb atoms for Fe or Ga in the ordered DO3 superlattice is beneficial in the formation of such tetragonal symmetry. Exchange couplings between the nearest Tb-Fe or Tb-Tb pairs of the tetragonal nanoparticles might generate strong localized magnetocrystalline anisotropy, leading to extraordinary magnetostriction enhancement.

  14. RERhZn (RE = Y, Sm, Gd-Lu) compounds with TiNiSi type structure - Synthesis and magnetic properties

    NASA Astrophysics Data System (ADS)

    Hermes, Wilfried; Pöttgen, Rainer

    2009-03-01

    The TiNiSi type intermetallic compounds RERhZn (RE = Y, Sm, Gd-Lu) were synthesized by induction melting of the elements in sealed tantalum ampoules. They were characterized by X-ray powder diffraction. Five structures were refined from single crystal X-ray diffractometer data: Pnma, Z = 4, a = 699.7(2), b = 405.6(2), c = 816.9(2) pm, wR2 = 0.038, 628 F2 values for SmRhZn, a = 696.1(2), b = 405.6(1), c = 811.9(3) pm, wR2 = 0.028, 886 F2 values for GdRhZn, a = 692.8(1), b = 403.0(1), c = 809.5(2) pm, wR2 = 0.039, 562 F2 values, for TbRhZn, a = 690.6(3), b = 401.50(9), c = 808.2(2) pm, wR2 = 0.036, 763 F2 values, for DyRhZn, and a = 688.6(5), b = 399.6(4), c = 808.3(7) pm, wR2 = 0.048, 546 F2 values for HoRhZn with 20 variables for each refinement. The rhodium atoms have coordination number 9 (5 RE + 4 Zn atoms) in the form of a tricapped trigonal prism. Together the rhodium and zinc atoms build up three-dimensional [RhZn] networks with short Rh-Zn (263-269 pm in GdRhZn) and Zn-Zn (296 pm in GdRhZn) distances. The gadolinium atoms bind to the [RhZn] network by Gd-Rh bonds (292-294 pm). Magnetic susceptibility measurements show Pauli paramagnetism for YRhZn and van Vleck paramagnetism for SmRhZn. The remaining RERhZn compounds are Curie-Weiss paramagnets which show magnetic ordering at low temperatures.

  15. Determination of crystal-field energy levels and temperature dependence of magnetic susceptibility for Dy3+ in [Dy2Pd] heterometallic complex.

    PubMed

    Karbowiak, Miros?aw; Rudowicz, Czes?aw; Ishida, Takayuki

    2013-11-18

    This study is the first in a series of experimental and theoretical investigations of the crystal-field (CF) energy levels obtained from optical electronic spectra for selected heterometallic 4f-3d compounds intensively studied for the development of novel single-molecule magnets (SMMs). An intriguing question is why the [{Dy(III)(hfac)3}2Cu(II)(dpk)2] (abbreviated as [Dy2Cu]; Hhfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dione, Hdpk = di-2-pyridyl ketoxime) has antiferromagnetic coupling, whereas [Gd2Cu] and heavy [Ln2Cu] systems usually show ferromagnetic coupling. As the first step to explain this peculiarity, the recently synthesized complex, [Dy2Pd], is investigated. This complex is isostructural with [Dy2Cu] yet contains the diamagnetic Pd ion instead of the magnetic Cu(II) ion. Experimental energy levels of Dy(3+) ions in the powder [Dy2Pd] sample were determined from the 4.2 K absorption spectra. CF analysis was performed yielding the fitted free ion and CF parameters. The number of freely varied parameters was restricted using the superposition model. The fittings yield very satisfactory agreement between the experimental and the calculated energy levels (rms = 12.0 cm(-1)). The energies and exact composition of the state vector for the ground multiplet (6)H(15/2) of Dy(3+) are determined. These results are used for the simulation of the temperature dependence of the magnetic susceptibility, which enables the theoretical interpretation of the experimentally measured magnetic susceptibility in the range 1.8-300 K for the [Dy2Pd] complex. This study provides background for the subsequent investigation of the magnetic exchange interactions in the pertinent heterometallic complexes. PMID:24187974

  16. Crystal growth, structure, and physical properties of Ln(Cu,Al)12 (Ln = Y, Ce, Pr, Sm, and Yb) and Ln(Cu, Ga)12 (Ln = Y, Gd-Er, and Yb).

    PubMed

    Drake, Brenton L; Capan, C; Cho, Jung Young; Nambu, Y; Kuga, K; Xiong, Y M; Karki, A B; Nakatsuji, S; Adams, P W; Young, D P; Chan, Julia Y

    2010-02-17

    Single crystals of Ln(Cu,Al)12 and Ln(Cu,Ga)12 compounds (Ln = Y, Ce-Nd, Sm, Gd-Ho, and Yb for Al and Ln = Y, Gd-Er, Yb for Ga) have been grown by flux-growth methods and characterized by means of single-crystal x-ray diffraction, complemented with microprobe analysis, magnetic susceptibility, resistivity and heat capacity measurements. Ln(Cu,Ga)12 and Ln(Cu,Al)12 of the ThMn12 structure type crystallize in the tetragonal I4/mmm space group with lattice parameters a approximately 8.59 Å and c approximately 5.15 Å and a approximately 8.75 Å and c approximately 5.13 Å for Ga and Al containing compounds, respectively. For aluminium containing compounds, magnetic susceptibility data show Curie-Weiss paramagnetism in the Ce and Pr analogues down to 50 K with no magnetic ordering down to 3 K, whereas the Yb analogue shows a temperature-independent Pauli paramagnetism. Sm(Cu,Al)12 orders antiferromagnetically at T(N)approximately 5 K and interestingly exhibits Curie-Weiss behaviour down to 10 K with no Van Vleck contribution to the susceptibility. Specific heat data show that Ce(Cu,Al)12 is a heavy fermion antiferromagnet with T(N) approximately 2 K and with an electronic specific heat coefficient ?0 as large as 390 mJ K2 mol(-1). In addition, this is the first report of Pr(Cu,Al)12 and Sm(Cu,Al)12 showing an enhanced mass (approximately 80 and 120 mJ K(2) mol(-1)). For Ga containing analogues, magnetic susceptibility data also show the expected Curie-Weiss behaviour from Gd to Er, with the Yb analogue being once again a Pauli paramagnet. The antiferromagnetic transition temperatures range over 12.5, 13.5, 6.7, and 3.4 K for Gd, Tb, Dy, and Er. Metallic behaviour is observed down to 3 K for all Ga and Al analogues. A large positive magnetoresistance up to 150% at 9 T is also observed for Dy(Cu,Ga)12. The structure, magnetic, and transport properties of these compounds will be discussed. PMID:21389376

  17. Two C3 -symmetric Dy3III complexes with triple di-?-methoxo-?-phenoxo bridges, magnetic ground state, and single-molecule magnetic behavior.

    PubMed

    Hänninen, Mikko M; Mota, Antonio J; Aravena, Daniel; Ruiz, Eliseo; Sillanpää, Reijo; Camón, Agustín; Evangelisti, Marco; Colacio, Enrique

    2014-07-01

    Two series of isostructural C(3)-symmetric Ln(3) complexes Ln(3)?[BPh(4)] and Ln(3)?0.33[Ln(NO(3))(6)] (in which Ln(III) =Gd and Dy) have been prepared from an amino-bis(phenol) ligand. X-ray studies reveal that Ln(III) ions are connected by one ?(2)-phenoxo and two ?(3)-methoxo bridges, thus leading to a hexagonal bipyramidal Ln(3)O(5) bridging core in which Ln(III) ions exhibit a biaugmented trigonal-prismatic geometry. Magnetic susceptibility studies and ab initio complete active space self-consistent field (CASSCF) calculations indicate that the magnetic coupling between the Dy(III) ions, which possess a high axial anisotropy in the ground state, is very weakly antiferromagnetic and mainly dipolar in nature. To reduce the electronic repulsion from the coordinating oxygen atom with the shortest Dy-O distance, the local magnetic moments are oriented almost perpendicular to the Dy(3) plane, thus leading to a paramagnetic ground state. CASSCF plus restricted active space state interaction (RASSI) calculations also show that the ground and first excited state of the Dy(III) ions are separated by approximately 150 and 177?cm(-1), for Dy(3)?[BPh(4)] and Dy(3)?0.33[Dy(NO(3))(6)], respectively. As expected for these large energy gaps, Dy(3)?[BPh(4)] and Dy(3)?0.33[Dy(NO(3)(6)] exhibit, under zero direct-current (dc) field, thermally activated slow relaxation of the magnetization, which overlap with a quantum tunneling relaxation process. Under an applied Hdc field of 1000?Oe, Dy(3)?[BPh(4)] exhibits two thermally activated processes with U(eff) values of 34.7 and 19.5?cm(-1), whereas Dy(3)?0.33[Dy(NO(3))(6)] shows only one activated process with Ueff =19.5?cm(-1). PMID:24890335

  18. Synthesis and characterization of the novel monoamide derivatives of Gd-TTDA.

    PubMed

    Wang, Yun-Ming; Li, Cha-Ru; Huang, Yu-Chin; Ou, Ming-Hung; Liu, Gin-Chung

    2005-01-24

    For this study, the N'-monoamide derivatives of TTDA (3,6,10-tri(carboxymethyl)-3,6,10-triazadodecanedioic acid), N'-methylamide (TTDA-MA), N'-benzylamide (TTDA-BA), and N'-2-methoxybenzylamide (TTDA-MOBA), were synthesized. Their protonation constants and stability constants (log K(ML)'s) formed with Ca(2+), Zn(2+), Cu(2+), and Gd(3+) were determined by potentiometric titration in 0.10 M Me(4)NCl at 25.0 +/- 0.1 degrees C. The relaxivity values of [Gd(TTDA-MA)](-), [Gd(TTDA-BA)](-), and [Gd(TTDA-MOBA)](-) remained constant with respect to pH changes over the range 4.5-12.0. The (17)O NMR chemical shift of H(2)O induced by [Dy(TTDA-MA)(H(2)O)](-) at pH 6.80 showed 0.9 inner-sphere water molecules. Water proton relaxivity values for [Gd(TTDA-MA)(H(2)O)](-), [Gd(TTDA-BA)(H(2)O)](-), and [Gd(TTDA-MOBA)(H(2)O)](-) at 37.0 +/- 0.1 degrees C and 20 MHz are 3.89, 4.21, and 4.25, respectively. The water-exchange lifetime (tau(M)) and rotational correlation time (tau(R)) of [Gd(TTDA-MA)(H(2)O)](-), [Gd(TTDA-BA)(H(2)O)](-), and [Gd(TTDA-MOBA)(H(2)O)](-) are obtained from reduced the (17)O relaxation rate and chemical shifts of H(2)(17)O. The (2)H NMR longitudinal relaxation rates of the deuterated diamagnetic lanthanum complexes for the rotational correlation time were also thoroughly investigated. The water-exchange rates (K(298)(ex) for [Gd(TTDA-MA)(H(2)O)](-), [Gd(TTDA-BA)(H(2)O)](-), and [Gd(TTDA-MOBA)(H(2)O)](-) are lower than that of [Gd(TTDA)(H(2)O)](2)(-) but significantly higher than those of [Gd(DTPA)(H(2)O)](2)(-) and [Gd(DTPA-BMA)(H(2)O)]. The rotational correlation times for [Gd(TTDA-BA)(H(2)O)](-) and [Gd(TTDA-MOBA)(H(2)O)](-) are significantly longer than those of [Gd(TTDA)(H(2)O)](2)(-) and [Gd(DTPA)(H(2)O)](2)(-) complexes. The marked increase of the relaxivity of [Gd(TTDA-BA)(H(2)O)](-) and [Gd(TTDA-MOBA)(H(2)O)](-) results mainly from their longer rotational correlation time. The noncovalent interaction between human serum albumin (HSA) and [Gd(TTDA-BA)(H(2)O)](-) and [Gd(TTDA-MOBA)(H(2)O)](-) complexes containing a hydrophobic substituent was investigated by measuring the water proton relaxation rate of the aqueous solutions. The binding association constant (K(A)) values are 1.0 +/- 0.2 x 10(3) and 1.3 +/- 0.2 x 10(3) M(-1) for [Gd(TTDA-BA)(H(2)O)](-) and [Gd(TTDA-MOBA)(H(2)O)](-), which indicates a stronger interaction of [Gd(TTDA-BA)(H(2)O)](-) and [Gd(TTDA-MOBA)(H(2)O)](-) with HSA. PMID:15651885

  19. Magnetic properties of Dy3+ in DyBa2Cu3O7-x

    Microsoft Academic Search

    J. A. Hodges; P. Imbert; J. B. Marimon da Cunha; J. Hammann; E. Vincent; J. P. Sanchez

    1988-01-01

    The high-Tc superconductor DyBa2Cu3O7-x (SC) and its oxygen deficient tetragonal non-superconducting counterpart (NSC) have been studied by DC magnetisation measurements down to 0.3 K and by 161Dy Mössbauer spectroscopy down to 0.05 K. The low-temperature Dy3+ magnetic properties, which are similar in the two compounds, show the influence of crystal fields and Dy-Dy magnetic correlations. The Dy3+ paramagnetic fluctuation rates

  20. Gamow-teller strength and particle-phonon states in 149 Dy from decay of its 11\\/2 ? and l\\/2 + 149 Ho parents

    Microsoft Academic Search

    R. Menegazzo; H. Güven; J. Styczen; N. Roy; P. Kleinheinz; D. Schardt; R. Barden; G. Walter; A. Huck; G. Marguier; J. Blomqvist

    1989-01-01

    Studies of the149Ho 11\\/2- and 1\\/2+ GT-decays using on-line mass separation have established in the N=83149Dy nucleus the single neutron excitations below 1.8 MeV and members of the ?f7\\/2×3- and ?f7\\/2×2+ particle-phonon multiplets. Quantitative analysis of the GT-decay strength to149Dy 1qp- and 3qp-states is made in terms of the strength values measured in149Dy0 and147Tb11\\/2- decay.

  1. Dy-V magnetic interaction and local structure bias on the complex spin and orbital ordering in Dy1?xTbxVO3 (x=0 and 0.2)

    DOE PAGESBeta

    Yan, J.-Q.; Cao, H. B.; McGuire, M. A.; Ren, Y.; Sales, B. C.; Mandrus, D. G.

    2013-06-01

    The spin and orbital ordering in Dy1?xTbxVO3 (x=0 and 0.2) was studied by measuring x-ray powder diffraction, magnetization, specific heat, and neutron single-crystal diffraction. The results show that G-OO/C-AF and C-OO/G-AF phases coexist in Dy0.8Tb0.20VO3 in the temperature range 2–60 K, and the volume fraction of each phase is temperature and field dependent. The ordering of Dy moments at T*?=?12 K induces a transition from G-OO/C-AF to a C-OO/G-AF phase. Magnetic fields suppress the long-range order of Dy moments and thus the C-OO/G-AF phase below T*. The polarized moments induced at the Dy sublattice by external magnetic fields couple tomore »the V 3d moments, and this coupling favors the G-OO/C-AF state. Also discussed is the effect of the Dy-V magnetic interaction and local structure distortion on the spin and orbital ordering in Dy1?xTbxVO3.« less

  2. Magnetic structure of Dy3+ in hexagonal multiferroic DyMnO3

    E-print Network

    Magnetic structure of Dy3+ in hexagonal multiferroic DyMnO3 S. Nandi,1,2 A. Kreyssig,1,2 J. Q. Yan the Dy3+ moments are aligned and antiferromagnetically correlated in the c direction according the splitting of ground-state doublet crystal-field levels of Dy3+ by the exchange field of Mn3+ . XRMS together

  3. Ferromagnetic Dy-Ni and antiferromagnetic Dy-Cu couplings in single-molecule magnets [Dy2Ni] and [Dy2Cu].

    PubMed

    Okazawa, Atsushi; Nogami, Takashi; Nojiri, Hiroyuki; Ishida, Takayuki

    2008-11-01

    The exchange couplings in [{Dy(hfac)3}2Cu(dpk)2] and [{Dy(hfac)3}2Ni(dpk)2(py)2] (Hdpk = di-2-pyridyl ketoxime) were precisely evaluated by high-frequency electron paramagnetic resonance and pulsed-field magnetization studies, giving J(Dy-Cu)/kB = -0.126 K and J(Dy-Ni)/kB = +0.031 K. PMID:18844348

  4. Magnetic properties of Fe{sub 2}P-type R{sub 6}CoTe{sub 2} compounds (R=Gd-Er)

    SciTech Connect

    Morozkin, A.V., E-mail: morozkin@general.chem.msu.r [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, Gsp-2, Moscow 119992 (Russian Federation); Mozharivskyj, Yu; Svitlyk, V. [Department of Chemistry, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4M1 (Canada); Nirmala, R. [Indian Institute of Technology Madras, Chennai 600 036 (India); Isnard, O. [Institute Laue-Langevin, 6 Rue J. Horowitz, 38042 Grenoble (France); Institut Neel du CNRS/Universite J.Fourier, BP166X, 38042 Grenoble (France); Manfrinetti, P.; Provino, A. [Dipartimento di Chimica, Universita di Genova, Via Dodecaneso 31, 16146 Genova (Italy); LAMIA Laboratory-CNR-INFM, Corso Perrone 24, 16152 Genova (Italy); Ritter, C. [Institute Laue-Langevin, 6 Rue J. Horowitz, 38042 Grenoble (France)

    2010-06-15

    The magnetic structure of the Fe{sub 2}P-type R{sub 6}CoTe{sub 2} phases (R=Gd-Er, space group P6-bar 2m) has been investigated through magnetization measurement and neutron powder diffraction. All phases demonstrate high-temperature ferromagnetic and low-temperature transitions: T{sub C}=220 K and T{sub CN}=180 K for Gd{sub 6}CoTe{sub 2}, T{sub C}=174 K and T{sub CN}=52 K for Tb{sub 6}CoTe{sub 2}, T{sub C}=125 K and T{sub CN}=26 K for Dy{sub 6}CoTe{sub 2}, T{sub CN}=60 K and T{sub N}=22 K for Ho{sub 6}CoTe{sub 2} and T{sub CN{approx}}30 K and T{sub N{approx}}14 K for Er{sub 6}CoTe{sub 2}. Between 174 and 52 K Tb{sub 6}CoTe{sub 2} has a collinear magnetic structure with K{sub 0}=[0, 0, 0] and with magnetic moments along the c-axis, whereas below 52 K it adopts a non-collinear ferromagnetic one. Below 60 K the magnetic structure of Ho{sub 6}CoTe{sub 2} is that of a non-collinear ferromagnet. The holmium magnetic components with a K{sub 0}=[0, 0, 0] wave vector are aligned ferromagneticaly along the c-axis, whereas the magnetic component with a K{sub 1}=[1/2, 1/2, 0] wave vector are arranged in the ab plane. The low-temperature magnetic transition at {approx}22 K coincides with the reorientation of the Ho magnetic component with the K{sub 0} vector from the collinear to the non-collinear state. Below 30 K Er{sub 6}CoTe{sub 2} shows an amplitude-modulate magnetic structure with a collinear arrangement of magnetic components with K{sub 0}=[0, 0, 0] and K{sub 1}=[1/2, 1/2, 0]. The low-temperature magnetic transition at {approx}14 K corresponds to the variation in the magnitudes of the M{sub Er}{sup K0} and M{sub Er}{sup K1} magnetic components. In these phases, no local moment was detected on the cobalt site. The magnetic entropy of Gd{sub 6}CoTe{sub 2} increases from {Delta}S{sub mag}=-4.5 J/kg K at 220 K up to {Delta}S{sub mag}=-6.5 J/kg K at 180 K for the field change {Delta}{mu}{sub 0}H=0-5 T. - Graphical abstract: The novel Fe{sub 2}P-type R{sub 6}CoTe{sub 2} phases (R=Gd-Er, space group P6-bar 2m) show ferromagnetic type ordering in the temperature range 14-220 K.All compounds demonstrate high-temperature ferromagnetic and low-temperature antiferromagnetic ordering.The magnetic entropy of Gd{sub 6}CoTe{sub 2} increases from {Delta}S{sub mag}=-4.5 J/kg K at 220 K up to {Delta}S{sub mag}=-6.5 J/kg K at 180 K for the field change {Delta}{mu}{sub 0}H=0-5 T.The R{sub 6}CoTe{sub 2} compounds exhibit the commensurate magnetic structures with wave vectors K{sub 0}=[0, 0, 0] and K{sub 1}=[1/2, 1/2, 1/2].

  5. Nuclear Moments of Tb157, Tb158, and Tb160 by Electron Paramagnetic Resonance and Nuclear Alignment

    Microsoft Academic Search

    Warren C. Easley; J. A. Barclay; D. A. Shirley

    1968-01-01

    Electron-paramagnetic-resonance experiments on yttrium ethylsulfate (YES) single crystals containing terbium isotopes in the relative abundances Tb159:Tb157:Tb158=25:1.6:1 were carried out at Q-band frequencies (35 GHz). The nuclear spin of Tb158 was found to be 3, and by comparison with the observed hyperfine structure of Tb159 and its known moment, a magnetic moment mu158=1.740(7) nm was calculated. Transitions due to Tb157 were

  6. Spin-reorientation in DyGa

    NASA Astrophysics Data System (ADS)

    Susilo, R. A.; Cadogan, J. M.; Muñoz-Pérez, S.; Cobas, R.; Hutchison, W. D.; Avdeev, M.

    2015-09-01

    We have used neutron powder diffraction to determine the magnetic structure of DyGa. This compound crystallises in the orthorhombic CrB-type structure with the Cmcm space group (#63) and the magnetic structure comprises ferromagnetic order of the Dy sublattice along the c-axis below TC=115 K. Upon cooling below 25 K, the Dy magnetic moments cant away from the c-axis towards the a-axis. At 3 K, the Dy moment is 9.8(2) ?B and the Dy magnetic moments point in the direction ? = 22(2) °, ? = 0 ° relative to the c-axis.

  7. Insertion of dimethylsilanone into a Ln-N bond and X-ray crystal structure of the insertion product [MeCpDy( ? 2-PzMe 2)( ?-? 1: ? 2-OSiMe 2PzMe 2)

    Microsoft Academic Search

    Xi-geng Zhou; Wei-wen Ma; Zu-en Huang; Rui-fang Cai; Xiao-zeng You; Xiao-ying Huang

    1997-01-01

    Reaction of MeCp3Ln(MeCp = COLLABCH3C5H4, Ln = Nd, Gd, Dy) with two equivalents of HPzMe2(HPzMe2 = 3,5-dimethylpyrazole) in THF at room temperature yielded complexes [MeCpLn(PzMe2)2] [Ln-Nd(1), Gd(2), Dy(3)], which have been characterized by elemental analysis, IR and MS spectra. The new complexes react with dimethylsilicone grease to give the dimethylsilanone insertion products: [MeCpLn(?2-PzMe2)(?-?1:?2-OSiMe2PzMe2)]2 [Nd(4), Gd(5), Dy(6)]. The complex 6 has

  8. Magnetic properties of Dy in Pb{sub 2}Sr{sub 2}DyCu{sub 3}O{sub 8}.

    SciTech Connect

    Movshovich, R.; Skanthakumar, S.; Soderholm, L.

    1999-07-02

    Superconductivity can be induced at high temperatures in Pb{sub 2}Sr{sub 2}RCu{sub 3}O{sub 8} (R - rare earth) by partially doping Ca{sup 2+} for R{sup 3+}. In order to understand the interplay between magnetism and superconductivity, the magnetic properties of the parent compounds, Pb{sub 2}Sr{sub 2}RCu{sub 3}O{sub 8}, have been studied. The work presented here includes magnetic susceptibility and specific heat measurements on R = Dy and extends our previous studies on R = Ce, Pr, Tb, Ho and Er. Specific heat experiments suggest that the Dy ions order antiferromagnetically with an ordering temperature of 1.3K. The magnetic susceptibility data are in good agreement with the susceptibility calculated using crystal field parameters that are extrapolated from previous modeling of the R = Er and Ho analogs of this series.

  9. Low-energy coexisting band in 154Gd.

    PubMed

    Kulp, W D; Wood, J L; Krane, K S; Loats, J; Schmelzenbach, P; Stapels, C J; Larimer, R-M; Norman, E B

    2003-09-01

    A low-energy coexisting band Jpi (Ex keV) 0(+) (1182), 2(+) (1418), 4(+) (1701) is identified in the deformed nucleus, 154Gd. Detailed gamma-ray spectroscopy following the beta decays of 154Eu (J=3), (g,m(1),m(2))154Tb (J=0,3,7) is used to establish this structure. The structure is explained in terms of the pairing and deformation degrees of freedom, a "pairing isomer," which results from the nu[505] upward arrow Nilsson intruder orbital. PMID:14525474

  10. Crystal Field Disorder in the Quantum Spin Ice Ground State of Tb2Sn2 xTixO7

    SciTech Connect

    Gaulin, Bruce D. [McMaster University; Zhang, J. [McMaster University; Dahlberg, M. L. [Pennsylvania State University; Matthews, Maria J. [Pennsylvania State University; Bert, F. [Universite Paris Sud, Orsay, France; Kermarrec, E. [Universite Paris Sud, Orsay, France; Fritsch, Katharina [McMaster University; Granroth, Garrett E [ORNL; Jiramongkolchai, P. [Princeton University; Amato, A. [Paul Scherrer Institut, Villigen, Switzerland; Baines, C. [Paul Scherrer Institut, Villigen, Switzerland; Cava, R. J. [Princeton University; Mendels, P. [Universite Paris Sud, Orsay, France; Schiffer, P [Pennsylvania State University

    2015-01-01

    Spin ice physics marries that of hydrogen disorder in water ice, first discussed almost 60 years ago by Pauling, and that of low temperature magnetism on certain networks of connected tetrahedra. Recently the classical spin ice mag- nets Ho2Ti2O7 and Dy2Ti2O7 have shown an emergent artificial magneto- statics , which manifests itself as Coulombic spin correlations and excitations behaving as diffusive magnetic monopoles. The related pyrochlore magnet, Tb2Ti2O7, has been proposed as a quantum variant of spin ice, stabilized by 1 virtual excitations between the crystal field (CF) ground state doublet appro- priate to Tb3+, and its low lying excited state doublet. Isostructural Tb2Sn2O7 displays soft spin ice order, and its Tb3+ ground and excited CF eigenstates are known to differ relative to those of Tb2Ti2O7. We present a comprehensive study of Tb2Sn2 xTixO7 showing a novel, dynamic spin liquid state for all x other than the end members (0, 2). This state is the result of disorder in the low lying Tb3+ CF environments which de-stabilizes the mechanism by which quantum fluctuations contribute to ground state selection in Tb2Sn2 xTixO7.

  11. Series of isostructural planar lanthanide complexes [Ln(III)4(mu3-OH)2(mdeaH)2(piv)8] with single molecule magnet behavior for the Dy4 analogue.

    PubMed

    Abbas, Ghulam; Lan, Yanhua; Kostakis, George E; Wernsdorfer, Wolfgang; Anson, Christopher E; Powell, Annie K

    2010-09-01

    A series of five isostructural tetranuclear lanthanide complexes of formula [Ln(4)(mu(3)-OH)(2)(mdeaH)(2)(piv)(8)], (mdeaH(2) = N-methyldiethanolamine; piv = pivalate; Ln = Tb (1), Dy (2), Ho (3), Er (4), and Tm (5)) have been synthesized and characterized. These clusters have a planar "butterfly" Ln(4) core. Magnetically, the Ln(III) ions are weakly coupled in all cases; the Dy(4) compound 2 shows Single Molecule Magnet (SMM) behavior. PMID:20704320

  12. Magnetic, Caloric and Crystallographic Properties of Dy5(SixGe1-x)4 Alloys

    SciTech Connect

    Vitaliy Vladislavovich Ivchenko

    2002-07-19

    Polycrystals of the intermetallic compound of the Dy{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} system, where x = 0, 0.25, 0.5, 0.625, 0.675, 0.725, 0.75, 0.775, 0.825, 0.875, and 1, have been prepared by electric-arc-melting on water-cooled copper hearth in an argon atmosphere. A study of phase relationships and crystallography in the pseudobinary system Dy{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} using X-ray powder diffraction data and optical metallography was completed. It revealed that silicides in the composition range from 0.825 to 1 crystallize in the Gd{sub 5}Si{sub 4}-type crystal structure: germanides in the composition range from 0 to 0.625 crystallize in the Sm{sub 5}Ge{sub 4}-type structure, and alloys with intermediate composition range from 0.675 to 0.775 crystallize in the monoclinic Gd{sub 5}Si{sub 2}Ge{sub 2}-type structure. The -{Delta}S{sub m} values were determined from magnetization measurements for 7 alloys. The alloys with a monoclinic crystal structure which belong to an intermediate phase region have large MCE value, which exceeds those observed in the other two phase regions by 300 to 500%. The nature of the observed magnetic and structural transformations in the Dy{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} system seems to be similar with those reported for the Gd{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} system. However, the interval and concentration range of three different phase regions in the Dy{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} system are different from that observed in Gd-based alloys. A non-collinear ordering of magnetic moments at low temperature was observed for the alloys with monoclinic crystal structure. The Dy{sub 5}Si{sub 3}Ge alloy exhibited FM phase transition below Curie temperature. A series of magnetic transitions were observed at low temperature in the Dy{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} alloys. The number of transitions increased and the magnetization decreased with increasing germanium content in the alloys. The -{Delta}S{sub m} and -{Delta}T values were calculated from heat capacity data for Dy{sub 5}Si{sub 3.5}Ge{sub 0.5} and Dy{sub 5}Si{sub 4} alloys only, due to the fragile nature of the germanides-rich samples. Based on the MCe values, the alloys from the orthorhombic Dy{sub 5}Si{sub 4}-based solid solution and the intermediate monoclinic phase regions may be useful magnetic refrigerant materials in the temperature range {approx}50K to -160K.

  13. Tricks to translating TB transcriptomics.

    PubMed

    Deffur, Armin; Wilkinson, Robert J; Coussens, Anna K

    2015-05-01

    Transcriptomics and other high-throughput methods are increasingly applied to questions relating to tuberculosis (TB) pathogenesis. Whole blood transcriptomics has repeatedly been applied to define correlates of TB risk and has produced new insight into the late stage of disease pathogenesis. In a novel approach, authors of a recently published study in Science Translational Medicine applied complex data analysis of existing TB transcriptomic datasets, and in vitro models, in an attempt to identify correlates of protection in TB, which are crucially required for the development of novel TB diagnostics and therapeutics to halt this global epidemic. Utilizing latent TB infection (LTBI) as a surrogate of protection, they identified IL-32 as a mediator of interferon gamma (IFN?)-vitamin D dependent antimicrobial immunity and a marker of LTBI. Here, we provide a review of all TB whole-blood transcriptomic studies to date in the context of identifying correlates of protection, discuss potential pitfalls of combining complex analyses originating from such studies, the importance of detailed metadata to interpret differential patient classification algorithms, the effect of differing circulating cell populations between patient groups on the interpretation of resulting biomarkers and we decipher weighted gene co-expression network analysis (WGCNA), a recently developed systems biology tool which holds promise of identifying novel pathway interactions in disease pathogenesis. In conclusion, we propose the development of an integrated OMICS platform and open access to detailed metadata, in order for the TB research community to leverage the vast array of OMICS data being generated with the aim of unraveling the holy grail of TB research: correlates of protection. PMID:26046091

  14. Tricks to translating TB transcriptomics

    PubMed Central

    Deffur, Armin; Wilkinson, Robert J.

    2015-01-01

    Transcriptomics and other high-throughput methods are increasingly applied to questions relating to tuberculosis (TB) pathogenesis. Whole blood transcriptomics has repeatedly been applied to define correlates of TB risk and has produced new insight into the late stage of disease pathogenesis. In a novel approach, authors of a recently published study in Science Translational Medicine applied complex data analysis of existing TB transcriptomic datasets, and in vitro models, in an attempt to identify correlates of protection in TB, which are crucially required for the development of novel TB diagnostics and therapeutics to halt this global epidemic. Utilizing latent TB infection (LTBI) as a surrogate of protection, they identified IL-32 as a mediator of interferon gamma (IFN?)-vitamin D dependent antimicrobial immunity and a marker of LTBI. Here, we provide a review of all TB whole-blood transcriptomic studies to date in the context of identifying correlates of protection, discuss potential pitfalls of combining complex analyses originating from such studies, the importance of detailed metadata to interpret differential patient classification algorithms, the effect of differing circulating cell populations between patient groups on the interpretation of resulting biomarkers and we decipher weighted gene co-expression network analysis (WGCNA), a recently developed systems biology tool which holds promise of identifying novel pathway interactions in disease pathogenesis. In conclusion, we propose the development of an integrated OMICS platform and open access to detailed metadata, in order for the TB research community to leverage the vast array of OMICS data being generated with the aim of unraveling the holy grail of TB research: correlates of protection. PMID:26046091

  15. Element Specific Magnetic Ordering in Nd0.75Dy0.25Fe3(BO3)4

    Microsoft Academic Search

    C. S. Nelson; L. N. Bezmaternykh; I. A. Gudim

    2010-01-01

    Interest in RFe3(BO3)4 has been motivated by the magnetoelectric properties of R = Gd and Nd, in which field-induced polarization phases are induced at modest (<1 T) magnetic fields. Spontaneous polarization has more recently been observed in the substituted ferroborate with R = Nd0.75Dy0.25.[1] Using rare earth L edge resonant x-ray scattering and nonresonant x-ray scattering, we have investigated the

  16. Coulomb excitation studies of ¹⁶°Dy, ¹⁶²Dy, and ¹⁶⁴Dy

    Microsoft Academic Search

    R. N. Oehlberg; L. L. Riedinger; A. E. Rainis; A. G. Schmidt; E. G. Funk; J. W. Mihelich

    1974-01-01

    Coulomb excitation measurements with ¹⁶O and ⁴He projectiles ; were performed on ¹⁶°Dy, ¹⁶²Dy and ¹⁶⁴Dy. The ground-state ; rotational bands up through the 8\\/sup +\\/ member were observed in the ¹⁶O ; experiments. The measured eccitation probabilities yield B(E2; I yields I -- ; 2) values which are generally in agreement with the rotational predictions except ; for the

  17. Renormalized Motion of Dysprosium Atoms Filling Boron Cages of DyB6

    NASA Astrophysics Data System (ADS)

    Iwasa, Kazuaki; Kuwahara, Keitaro; Utsumi, Yoshihiro; Saito, Kotaro; Kobayashi, Hiroki; Sato, Takahiro; Amano, Mitsuhide; Hasegawa, Takumi; Ogita, Norio; Udagawa, Masayuki; Tsutsui, Satoshi; Baron, Alfred Q. R.

    2012-11-01

    The lattice dynamics of DyB6 are investigated by an inelastic X-ray scattering technique. The measured phonon modes are dominated by the motion of Dy ions in oversized boron cages. These soften remarkably as temperature is decreased, with the energy of the longitudinal phonon for the propagation vector \\mbi{q}1=(1/2,0,0) decreasing by 29% from 300 K down to the phase transition temperature of 31 K. The dispersion relation curves show kinklike anomalies at \\mbi{q}k=(0.38,0.38,0). The observed phenomena are very similar to those previously observed in GdB6 [Iwasa et al.: Phys. Rev. B 84 (2011) 214308]. We note analogous phonon anomalies in the heavier rare-earth hexaboride systems, owing to the interplay between the motion of rare-earth atoms and the electronic state, particularly characterized by the Friedel oscillation.

  18. UBC World TB Day TB Awareness Day at the University of British Columbia

    E-print Network

    Michelson, David G.

    insights into within-host diversity" · Nash Dhalla, TB Nurse Consultant - BC Centre for Disease Control "STOP TB Canada Intro" and " TB nursing in BC " 12:15 ­ 1:30 pm Lunch LSC 1330 Free catered lunch

  19. First-Line Treatment for Tuberculosis (TB), Drug Resistant TB -- A Visual Tour

    MedlinePLUS

    ... Content Area First-Line Treatment of TB for Drug-Sensitive TB Tuberculosis, which results from an infection ... Click here to see how these drugs work . Drug-Resistant TB—A Visual Tour First-Line Treatment ...

  20. Planar tetranuclear lanthanide clusters with the Dy4 analogue displaying slow magnetic relaxation.

    PubMed

    Langley, Stuart K; Chilton, Nicholas F; Gass, Ian A; Moubaraki, Boujemaa; Murray, Keith S

    2011-12-21

    Two isostructural tetranuclear lanthanide clusters of general formula [Ln(III)(4)(?(3)-OH)(2)(o-van)(4)(O(2)CC(CH(3))(3))(4)(NO(3))(2)]·CH(2)Cl(2)·1.5H(2)O (Ln = Gd (1) and Dy (2)) (o-van = 3-methoxysalicylaldehydato anion) are reported. The metallic cores of both complexes display a planar 'butterfly' arrangement. Magnetic studies show that both are weakly coupled, with 2 displaying probable SMM behaviour. PMID:22031449

  1. Tb 3+ luminescence enhancement of YAG:Tb 3+ nanocrystals embedded in silica xerogel

    Microsoft Academic Search

    Mariusz Kubus; H.-Jürgen Meyer; Lorenz Kienle; Andrzej M. K?onkowski

    2009-01-01

    The luminescence behavior of composite materials consisting of nanocrystals of Y3?xAl5O12:Tb (YAG:Tb3+) embedded into silica xerogel has been studied. Blue and green luminescence of the materials is due to a cross-relaxation effect in Tb3+ ions doped into a YAG lattice. The materials with YAG:Tb3+ nanocrystals immobilized in silica exhibit enhancement of Tb3+ luminescence in comparison with the macrocrystalline YAG:Tb3+ powder.

  2. Spectral properties and emission efficiencies of GdVO4 phosphors

    NASA Astrophysics Data System (ADS)

    Anitha, M.; Ramakrishnan, P.; Chatterjee, A.; Alexander, G.; Singh, H.

    GdVO4 with activators Eu, Dy, Sm and Bi has been synthesised by a solid-state reaction. GdVO4:Eu3+ (3%) yielded the highest quantum efficiency of 95%. Interesting energy-transfer properties have been revealed in the mixed-activator phosphor (GdVO4:Eu3+, Sm3+) when excited in the 4f shell of Sm3+ at 408 nm. Bismuth-activated GdVO4 gives rise to a broad-band emission peaking at 525 nm in comparison to YVO4:Bi3+, which gives an emission peak at 570 nm under UV excitation. The quantum efficiency of GdVO4:Bi3+ increases gradually with bismuth concentration and reaches a maximum of 80% for a bismuth concentration of 0.5%. There is a shift in the excitation band of GdVO4:Bi3+ towards longer wavelengths with increasing concentration of bismuth, which can lead to energy transfer from bismuth to europium in a phosphor with both these activators. Heat treatment of GdVO4:Bi3+ at 1500 °C for 3-3.5 h resulted in a large percentage of bismuth being lost from the lattice as evaluated by X-ray fluorescence. However, if a large percentage of bismuth (of the order of 3% or more) is initially added, a sufficient quantity of bismuth can still be retained after heat treatment, which can lead to the development of ceramic scintillators for X-ray tomographic applications. Addition of 3-5% boron gives a white GdVO4 phosphor without any chemical treatment.

  3. New orthorhombic derivative of CaCu{sub 5}-type structure: RNi{sub 4}Si compounds (R=Y, La, Ce, Sm, Gd–Ho), crystal structure and some magnetic properties

    SciTech Connect

    Morozkin, A.V., E-mail: morozkin@general.chem.msu.ru [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Knotko, A.V. [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Yapaskurt, V.O. [Department of Petrology, Geological Faculty, Moscow State University, Leninskie Gory, Moscow 119992 (Russian Federation); Yuan, Fang; Mozharivskyj, Y. [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1 (Canada); Nirmala, R. [Indian Institute of Technology Madras, Chennai 600036 (India)

    2013-12-15

    The crystal structure of new YNi{sub 4}Si-type RNi{sub 4}Si (R=Y, La, Ce, Sm, Gd–Ho) compounds has been established using powder X-ray diffraction. The YNi{sub 4}Si structure is a new structure type, which is orthorhombic derivative of CaCu{sub 5}-type structure (space group Cmmm N 65, oC12). GdNi{sub 4}Si and DyNi{sub 4}Si compounds order ferromagnetically at 25 and 19 K, respectively whereas YNi{sub 4}Si shows antiferromagnetic nature. At 15 K, DyNi{sub 4}Si shows second antiferromagnetic-like transition. The magnetic moment of GdNi{sub 4}Si at 5 K in 50 kOe field is ?7.2 ?{sub B}/f.u. suggesting a completely ordered ferromagnetic state. The magnetocaloric effect of GdNi{sub 4}Si is calculated in terms of isothermal magnetic entropy change and it reaches the maximum value of ?12.8 J/kg K for a field change of 50 kOe near T{sub C} ?25 K. - Graphical abstract: The RNi{sub 4}Si (R=Y, La, Ce, Sm, Gd–Ho) compounds crystallize in new YNi{sub 4}Si-type structure which is orthorhombic derivative of the basic CaCu{sub 5}-type structure. GdNi{sub 4}Si and DyNi{sub 4}Si compounds show the ferromagnetic-like ordering, whereas.YNi{sub 4}Si has the antiferromagnetic nature. The GdNi{sub 4}Si demonstrates the big magnetocaloric effect near temperature of ferromagnetic ordering. The relationship between initial CaCu{sub 5}-type DyNi{sub 5} and YNi{sub 4}Si-type DyNi{sub 4}Si lattices.

  4. Ternary Dy-Er-Al magnetic refrigerants

    DOEpatents

    Gschneidner, K.A. Jr.; Takeya, Hiroyuki

    1995-07-25

    A ternary magnetic refrigerant material comprising (Dy{sub 1{minus}x}Er{sub x})Al{sub 2} for a magnetic refrigerator using the Joule-Brayton thermodynamic cycle spanning a temperature range from about 60K to about 10K, which can be adjusted by changing the Dy to Er ratio of the refrigerant. 29 figs.

  5. A TB Space Which is Not Katetov TB

    E-print Network

    Fleissner, William G.

    1980-06-01

    such that xa G Vß. Since r e « and r is TB, by Lemmas 3 and 4, SX/3) G r. Thus xa e Vß Ç] S(ß) c Q - A,Vß[\\ S(ß) G r. LEMMA 8. \\A\\ = o^. PROOF. By définition a a). Then A f] Vß Ç] S(a) = {xß}. Finally, we define a TB topology coarser than z. Set z' = {Uzz: (x0tU)or\\r - U\\ < œi}. Clearly z' is a topology and z' c z. By Lemma 3 : , * agree on count­ able sets...

  6. Optical spectra of Ln 3+(Nd 3+, Sm 3+, Dy 3+, Ho 3+, Er 3+)-doped Y 3GaO 6

    Microsoft Academic Search

    F. S. Liu; Q. L. Liu; J. K. Liang; J. Luo; L. T. Yang; G. B. Song; Y. Zhang; L. X. Wang; J. N. Yao; G. H. Rao

    2005-01-01

    Ln3+ (Ln=Nd, Sm, Eu, Gd, Dy, Ho, Er)-doped Y3GaO6 compounds were prepared by solid-state reaction, and their optical spectra such as absorption, photoluminescence, excitation and time-resolved spectra have been measured for Ln=Nd, Sm, Dy, Ho, Er. X-ray powder diffraction shows that the lattice parameters of the compounds (Y0.96Ln0.04)3GaO6 decrease with the decrease of the radii of trivalent Ln3+ ions, indicating

  7. Simulation of the magnetocaloric effect in Tb nanofilms

    SciTech Connect

    Anselmo, Dory Hélio A. L., E-mail: doryh@dfte.ufrn.br [Departamento de Física Teórica e Experimental (DFTE), Universidade Federal do Rio Grande do Norte (UFRN), Natal-RN (Brazil); Mello, Vamberto D. [Departamento de Física,Universidade do Estado do Rio Grande do Norte (UERN), Mossoró-RN (Brazil); Vasconcelos, Manoel S. [Escola de Ciência e Tecnologia (ECT), Universidade Federal do Rio Grande do Norte (UFRN), Natal-RN (Brazil)

    2014-03-31

    Rare-earth (RE) metals have different magnetic structures resulting from the competition between the crystal-field and exchange interactions. When a magnetic field is applied it creates a third interaction and the magnetic structures are more complicated. In thin films, it is expected that even the magnetic arrangement itself can be strongly modified. Rare-earth helimagnets such as Terbium (Tb), Holmium (Ho) and Dysprosium (Dy) represent the best candidates to evidence such finite-size effects. This finite-size effect is caused by the reduced number of atoms in the direction perpendicular to the film plane that leads to a decrease of the total magnetic exchange energy. We report this contribution to the investigation of magnetocaloric effect (MCE) of thin Terbium films in the helimagnetic temperature range, from T{sub C} = 219 K to T{sub N} = 231 K, for external fields of the order of 1 kOe. We find that for strong fields, H = 50 kOe, the adiabatic temperature change ?T near the Néel temperature is around 15 K for any thickness of Tb films. However large thickness effects are found for small values of the magnetic field. For field strength of the order of a few kOe, the thermocaloric efficiency increases significantly for ultrathin (nanomagnetic) films.

  8. Framework of behavioral indicators for outcome evaluation of TB health promotion: a Delphi study of TB suspects and Tb patients

    PubMed Central

    2014-01-01

    Background Health promotion for prevention and control of Tuberculosis (TB) is implemented worldwide because of its importance, but few reports have evaluated its impact on behavior due to a lack of standard outcome indicators. The objective of this study was to establish a framework of behavioral indicators for outcome evaluation of TB health promotion among TB suspects and patients. Methods A two-round modified Delphi method involving sixteen TB control experts was used to establish a framework of behavioral indicators for outcome evaluation of TB health promotion targeted at TB suspects and patients. Results Sixteen of seventeen invited experts in TB control (authority score of 0.91 on a 1.0 scale) participated in round 1 survey. All sixteen experts also participated in a second round survey. After two rounds of surveys and several iterations among the experts, there was consensus on a framework of indicators for measuring outcomes of TB health promotion for TB suspects and patients. For TB suspects, the experts reached consensus on 2 domains (“Healthcare seeking behavior” and “Transmission prevention”), 3 subdomains (“Seeking care after onset of TB symptoms”, “Pathways of seeking care” and “Interpersonal contact etiquette”), and 8 indicators (including among others, “Length of patient delay”). For TB patients, consensus was reached on 3 domains (“Adherence to treatment”, “Healthy lifestyle” and “Transmission prevention”), 8 subdomains (including among others, “Adherence to their medication”), and 14 indicators (including “Percentage of patients who adhered to their medication”). Operational definitions and data sources were provided for each indicator. Conclusions The findings of this study provide the basis for debate among international experts on a framework for achieving global consensus on outcome indicators for TB health promotion interventions targeted at TB patients and suspects. Such consensus will help to increase effectiveness of TB health promotion, while ensuring international comparability of outcome data. PMID:24884569

  9. Low-temperature studies of the magnetic and superconducting properties of the R2 Ir3 Si5 (R=Y,La,Ce-Nd,Gd-Tm) system

    NASA Astrophysics Data System (ADS)

    Singh, Yogesh; Pal, D.; Ramakrishnan, S.

    2004-08-01

    Polycrystalline samples of the ternary rare-earth silicide compounds R2Ir3Si5 (R=Y,La,Ce-Nd,Gd-Tm) have been prepared and characterized using room temperature powder x-ray, magnetic susceptibility, electrical resistivity, and low-temperature (1.6-30K) zero-field heat capacity measurements. All the compounds crystallize in the tetragonal U2Co3Si5 type structure (space group Ibam). The effective moments estimated from Curie-Weiss fits to the high-temperature inverse susceptibility data suggest that Ir may carry an induced moment in these compounds. The systematics of the lattice parameters across the series suggest that Ce is trivalent in Ce2Ir3Si5 , whereas the magnetic, transport, and heat capacity measurements reveal a nonmagnetic behavior for this compound, suggesting that this is a strongly hybridized compound similar to Ce2Rh3Si5 . Pr2Ir3Si5 also does not order down to 1.8K . Large and prominent peaks at low temperatures in the susceptibility and heat capacity of the other magnetic rare-earth-containing compounds indicate bulk magnetic ordering of trivalent rare-earth moments in these compounds. The heat capacity data for Gd2Ir3Si5 show three anomalies, one above and one below the main ? type antiferromagnetic transition peak at 11.8K , while the data for Tb2Ir3Si5 also suggest two transitions. Most of the compounds have transition temperatures which follow the de Gennes scaling. However, Nd2Ir3Si5 and Tb2Ir3Si5 have anomalously large transition temperatures compared to that expected by the de Gennes scaling. Large crystalline electric field effects are indicated by the reduced value of the magnetic entropy at 30K , and this could be a possible reason for the deviation of the ordering temperature TN from the de Gennes factor. From the temperature dependence of the magnetic entropy we conclude that Nd2Ir3Si5 , Tb2Ir3Si5 , Dy2Ir3Si5 , and Ho2Ir3Si5 are in a doublet ground state. The anomalies in the susceptibility and heat capacity near 2K for La2Ir3Si5 and 2.9K for Y2Ir3Si5 suggest that these compounds undergo a transition into the superconducting state at low temperatures. A reduced jump ?C/?TC at TC and a large linear term in the temperature dependence of the heat capacity in the superconducting state are observed, and we compare this with similar behavior seen in the nonmagnetic superconducting members of the structurally related series R2Fe3Si5 , where it has been suggested that a fraction of the Fermi surface remains normal below TC .

  10. Morphotropic phase boundary and magnetoelastic behaviour in ferromagnetic Tb1-xGdxFe2 system

    NASA Astrophysics Data System (ADS)

    Adil, Murtaza; Yang, Sen; Mi, Meng; Zhou, Chao; Wang, Jieqiong; Zhang, Rui; Liao, Xiaoqi; Wang, Yu; Ren, Xiaobing; Song, Xiaoping; Ren, Yang

    2015-03-01

    Morphotropic phase boundary (MPB), separating two ferroic phases of different crystal symmetries, has been studied extensively for its extraordinary enhancement of piezoelectricity in ferroelectrics. Based on the same mechanism, we have designed a magnetic MPB in the pseudobinary ferromagnetic system of Tb1-xGdxFe2 and the corresponding crystal structure, magnetic properties, and magnetostriction are explored. With the synchrotron x-ray diffractometry, the structure symmetry of TbFe2-rich compositions is detected to be rhombohedral (R) and that of GdFe2-rich compositions is tetragonal (T) below Tc. With the change of concentration, the value of magnetostriction of the samples changes monotonously, while the MPB composition Tb0.1Gd0.9Fe2, which corresponds to the coexistence of R and T phases, exhibits the maximum magnetization among all available compositions and superposition of magnetostriction behaviour of R and T phases. Our result of MPB phenomena in ferromagnets may provide an effective route to design functional magnetic materials with exotic properties.

  11. Magnetic Structure of DyC2

    Microsoft Academic Search

    Masao Atoji

    1968-01-01

    The compound, DyC2, having the tetragonal body-centered CaC2-type structure has been shown by neutron diffraction to exhibit the magnetic spin alignment of a linear, transverse wave mode below the Ne´el temperature of 59°K. This static moment wave is propagating along the a axis and is polarized in the c-axis direction. The root-mean-square and maximum saturation moments per Dy are 8.37

  12. Hydrogenation effect on the Curie temperatures of amorphous (Tb\\/Dy)?Co alloys

    Microsoft Academic Search

    A. S. Andreenko; V. N. Verbetsky; S. A. Nikitin; N. S. Perov; A. A. Salamova; Yu. V. Skourski; N. V. Tristan; V. I. Jakovlev

    1996-01-01

    The effect of hydrogenizing on the magnetic properties of rare earth-cobalt amorphous alloys was investigated by means of measuring the magnetization and magnetic susceptibility. The hydrogenizing leads to a Curie temperature increase and hysteresis loop changes. Various mechanisms of these phenomena were supposed.

  13. Studies on sintered permanent magnets RE-Fe-M-Co-B Nd, Pr, Dy, Tb; M =

    E-print Network

    Boyer, Edmond

    RE-(Fe, Co, M) aux joints de grains est responsable de l'inhibition des corrosions acide et the advantageous corrosive and magnetic properties of the Nd-(Fe, Co)-B magnets, Article published online by EDP

  14. Application of GD&T

    NSDL National Science Digital Library

    Castro-Cedeno, Mario H.

    Many students that take a Geometric Dimensioning and Tolerancing (GD&T) course complain that they lack confidence in applying the concepts learned. One reason is not enough opportunities during the course to practice with assemblies instead of the simple parts typically shown in introductory textbooks. The specification of GD&T controls on the skateboard is an exercise that demonstrates that many possible correct solutions exist, depending on the intent of the designer. Only the mating between the skateboard deck and the truck base is studied in detail in this lesson. Other design, manufacturing and assembly issues that can be resolved with the use of GD&T can also be studied and some will be introduced in this ALT.

  15. Lifetime measurements and shape coexistence in {sup 144}Dy

    SciTech Connect

    Procter, M. G.; Cullen, D. M.; Niclasen, B.; Mason, P. J. R.; Rigby, S. V.; Dare, J. A.; Lumley, N. M. [Schuster Laboratory, University of Manchester, Manchester M13 9PL (United Kingdom); Scholey, C.; Greenlees, P. T.; Jakobsson, U.; Jones, P. M.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Nyman, M.; Puurunen, A.; Rahkila, P.; Ruotsalainen, P.; Saren, J. [Department of Physics, University of Jyvaeskylae, FIN-40014 Jyvaeskylae (Finland)

    2010-05-15

    The known level scheme of {sup 144}Dy has been extended and lifetime measurements have been made with the recoil-distance Doppler-shift method. Reduced transition probabilities and deformations have been determined for four low-lying transitions. These states form part of the first observed band crossing, giving information on the change in nuclear deformation resulting from the rearrangement of h{sub 11/2} protons in the nucleus. Two bands built upon excited 10{sup +} states have been assigned pi(h{sub 11/2}){sup 2} prolate and nu(h{sub 11/2}){sup -2} oblate configurations with tau=12(2)ps and 0.01Gd.

  16. Synthesis and photoluminescence characteristics of Dy{sup 3+} doped NaY(WO{sub 4}){sub 2} phosphors

    SciTech Connect

    Liu, Xiaohua, E-mail: xhliuxhliu@tom.com [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China)] [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Xiang, Wendou; Chen, Fengming; Hu, Zhengfa; Zhang, Wei [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China)] [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China)

    2013-02-15

    Graphical abstract: The phosphor powders of NaY(WO{sub 4}){sub 2}: Dy{sup 3+} were prepared by solid state reaction. For the different kinds of excitations, the dependence of luminescence intensity on the Tb{sup 3+} concentration was investigated. Display Omitted Highlights: ? We synthesize NaY(WO{sub 4}){sub 2}:Dy{sup 3+} phosphors by the solid-state reaction technique. ? We observe and explain the change of Y/B ratio with Dy{sup 3+} content. ? The I?x curve shows different behavior for different excitations. ? The concentration quenching mechanism is the d–d interaction. -- Abstract: The novel phosphor powders of NaY(WO{sub 4}){sub 2} doped with Dy{sup 3+} were synthesized by solid state reaction. X-ray diffraction analysis showed that the phosphors sintered at 900 °C for 6 h were a pure NaY(WO{sub 4}){sub 2} phase for all the Dy{sup 3+} doping concentrations. The room temperature excitation spectra of the phosphors vary with the Dy{sup 3+} concentration and consist of an intense charge transfer band of WO{sub 4}{sup 2?} groups and weak f–f transition absorption peaks of Dy{sup 3+}. The photoluminescence spectra, excited at the peak wavelength of charge transfer band, exhibit three bands centered at 488, 575 and 662 nm, which originate from the transitions of {sup 4}F{sub 9/2} ? {sup 6}H{sub 15/2} (blue), {sup 4}F{sub 9/2} ? {sup 6}H{sub 13/2} (yellow) and {sup 4}F{sub 9/2} ? {sup 6}H{sub 11/2} (red) of Dy{sup 3+}, respectively. The effects of Dy{sup 3+} concentration on luminescence intensity and the yellow-to-blue intensity ratio of the phosphors were investigated. The different behaviors for the doping concentration dependence of luminescence intensity resulted from the different kinds of excitation was discussed.

  17. Two-dimensional coordination polymers constructed by [Ni(II)Ln(III)] nodes and [W(IV)(bpy)(CN)6]2- spacers: a network of [Ni(II)Dy(III)] single molecule magnets.

    PubMed

    Alexandru, Maria-Gabriela; Visinescu, Diana; Shova, Sergiu; Lloret, Francesc; Julve, Miguel; Andruh, Marius

    2013-10-01

    Three isomorphous two-dimensional (2D) coordination polymers of general formula {[Ni(II)(valpn)Ln(III)(NO3)(H2O)(?-NC)4W(IV)(bipy)(CN)2]·xH2O·yCH3CN}n have been synthesized by reacting Ph4P[W(V)(CN)6(bipy)] with the heterodinuclear [Ni(II)Ln(III)(valpn)(O2NO)3] complexes [H2valpn = 1,3-propanediyl-bis(2-iminomethylene-6-methoxyphenol), bipy = 2,2'-bipyridine, and Ln = Gd (1), Dy (2), and Tb (3) with x = 2 (1), 3.9 (2), and 3.35 (3) and y = 2.50 (1), 2 (2), and 1.8 (3)]. Their crystal structures consist of [Ni(II)Ln(III)] 3d-4f nodes which are connected by [W(IV)(bipy)(CN)6](2-) diamagnetic linkers resulting from the reduction of W(V) to W(IV) during the reaction process. The Ni(II) and Ln(III) ions occupy the inner and outer coordination sites of the dideprotonated valpn ligand, respectively, and they are doubly bridged by the phenoxo oxygen atoms of such a ligand. The value of Ni(II)···Ln(III) separation through this bridge is 3.4919(10) (1), 3.4760(10) (2), and 3.4799(9) (3) Å, and those of the angles at the bridgehead phenoxo atoms are 106.6(2) and 107.3(2) (1), 106.9(2), and 107.8(2) (2) and 106.5(2)-106.8(2)° (3). Each W(IV) is eight-coordinated with a bidentate bipy molecule and six cyanide-carbon atoms building a somewhat distorted square antiprism environment. The rare-earth cations are nine-coordinated, the donor atoms describing a monocapped square antiprism for 1 and 3 and a tricapped trigonal prism for 2. Magnetic susceptibility measurements in the temperature range 1.9-300 K show the occurrence of ferromagnetic interactions between the Ni(II) and Ln(III) ions in 1-3. Frequency-dependent alternating susceptibility signals were observed for the Dy(III) derivative below 8.0 K under an applied dc field of 2500 G indicating the presence of slow magnetic relaxation with values of the pre-exponential factor (?0) and energy barrier (E(#)) of ca. 5.7 × 10(-8) s and 15.9 cm(-1), respectively. Complex 2 constitutes the first example of a 2D 3d-4f heterobimetallic single molecule magnet (SMM). PMID:24067093

  18. Unique Y-shaped lanthanide aggregates and single-molecule magnet behaviour for the Dy4 analogue.

    PubMed

    Xue, Shufang; Guo, Yun-Nan; Zhao, Lang; Zhang, Peng; Tang, Jinkui

    2014-01-28

    The assembly of N'-(amino-(pyrimidin-2-yl)methylene)-o-vanilloyl hydrazine ligands (H2L, Scheme 1) with different lanthanide perchlorates produces novel Y-shaped tetranuclear complexes, [Ln4(?3-OH)(L(2-))4(H2O)6]·(ClO4)3·6H2O, where Ln = Tb (1), Dy (2) and Ho (3). The formation of this unprecedented Y-shaped topology is largely ascribed to the versatility of the mixed-donor hydrazone ligands in terms of their potential denticity. Analysis of the susceptibility data shows that only the Dy-based molecule features SMM-like behaviour. The synthetic methodology of employing H2L and related ligands has provided a very promising route towards new families of magnetic coordination clusters with novel metal topologies and properties. PMID:24213812

  19. Photo- and cathodoluminescence of hydrothermally synthesized Y{sub 3}Al{sub 5}O{sub 12}:Tb and NaY(WO{sub 4}){sub 2}:Tb

    SciTech Connect

    Phillips, M.L.F.; Potter, B.G. Jr.

    1995-10-01

    Cathodoluminescent (CL) phosphors with improved low-voltage characteristics are needed for use in emissive flat panel displays. Conventional high-temperature methods for phosphor synthesis yield large polycrystalline grains that must be pulverized prior to screen deposition. Grinding has been implicated in reducing phosphor efficiency by causing surface contamination and defects. Hydrothermal synthesis has been used to improve the quality of ceramic powders by producing fine, well-formed crystallites without grinding. Two green-emitting phosphors, Y{sub 3}Al{sub 5}O{sub 12}:Tb (YAG:Tb) and NaY(WO{sub 4}){sub 2}:Tb, were used to test the effects of hydrothermal. synthesis on grain size and morphology, and on low-voltage CL properties. YAG:Th prepared hydrothermally consisted of submicron crystallites with a typical garnet habit. The CL efficiency of hydrothermally synthesized YAG:Tb (3 lm/W at 800 V) was comparable to that of equivalent YAG:Tb compositions prepared via high-temperature solid state reaction. In comparison, CL intensities of Gd{sub 3}Ga{sub 5}O{sub l2}:Tb were slightly better (3.5 lm/W at 800 V), while those of NaY(WO{sub 4}){sub 2}:Tb were approximately 1/100th that of YAG:Tb. Both CL and photoluminescence data show that the difference in the cathodoluminescence of YAG and NaY(WO{sub 4}){sub 2} can be understood in terms of differences in the mechanism of activation.

  20. Sensitisation of Eu(III)- and Tb(III)-based luminescence by Ir(III) units in Ir/lanthanide dyads: evidence for parallel energy-transfer and electron-transfer based mechanisms.

    PubMed

    Sykes, Daniel; Cankut, Ahmet J; Ali, Noorshida Mohd; Stephenson, Andrew; Spall, Steven J P; Parker, Simon C; Weinstein, Julia A; Ward, Michael D

    2014-05-01

    A series of blue-luminescent Ir(III) complexes with a pendant binding site for lanthanide(III) ions has been synthesized and used to prepare Ir(III)/Ln(III) dyads (Ln = Eu, Tb, Gd). Photophysical studies were used to establish mechanisms of Ir?Ln (Ln = Tb, Eu) energy-transfer. In the Ir/Gd dyads, where direct Ir?Gd energy-transfer is not possible, significant quenching of Ir-based luminescence nonetheless occurred; this can be ascribed to photoinduced electron-transfer from the photo-excited Ir unit (*Ir, (3)MLCT/(3)LC excited state) to the pendant pyrazolyl-pyridine site which becomes a good electron-acceptor when coordinated to an electropositive Gd(III) centre. This electron transfer quenches the Ir-based luminescence, leading to formation of a charge-separated {Ir(4+)}?-(pyrazolyl-pyridine)?(-) state, which is short-lived possibly due to fast back electron-transfer (<20 ns). In the Ir/Tb and Ir/Eu dyads this electron-transfer pathway is again operative and leads to sensitisation of Eu-based and Tb-based emission using the energy liberated from the back electron-transfer process. In addition direct Dexter-type Ir?Ln (Ln = Tb, Eu) energy-transfer occurs on a similar timescale, meaning that there are two parallel mechanisms by which excitation energy can be transferred from *Ir to the Eu/Tb centre. Time-resolved luminescence measurements on the sensitised Eu-based emission showed both fast and slow rise-time components, associated with the PET-based and Dexter-based energy-transfer mechanisms respectively. In the Ir/Tb dyads, the Ir?Tb energy-transfer is only just thermodynamically favourable, leading to rapid Tb?Ir thermally-activated back energy-transfer and non-radiative deactivation to an extent that depends on the precise energy gap between the *Ir and Tb-based (5)D4 states. Thus, the sensitised Tb(iii)-based emission is weak and unusually short-lived due to back energy transfer, but nonetheless represents rare examples of Tb(III) sensitisation by a energy donor that could be excited using visible light as opposed to the usually required UV excitation. PMID:24608523

  1. {beta} decay of {sup 148}Dy: Study of the Gamow-Teller giant state by means of total absorption spectroscopy

    SciTech Connect

    Algora, A.; Nacher, E.; Rubio, B.; Cano-Ott, D.; Tain, J.L.; Gadea, A.; Agramunt, J.; Karny, M.; Janas, Z.; Rykaczewski, K.; Collatz, R.; Hellstroem, M.; Hu, Z.; Kirchner, R.; Roeckl, E.; Shibata, M.; Batist, L.; Moroz, F.; Wittmann, V. [IFIC, CSIC-University Valencia, Apartado Oficial 22085, 46071 Valencia (Spain); Institute of Experimental Physics, Warsaw University, PL-00-681, Warsaw (Poland); Gessellschaft fuer Schwerionenforschung, D-64220 Darmstadt (Germany); St. Petersburg Nuclear Physics Institute, 188-350 Gatchina (Russian Federation)

    2004-12-01

    The {gamma}-cascades following the Gamow Teller beta decay of {sup 148}Dy 0{sup +} have been investigated with the total absorption gamma spectrometer at GSI. Our measurements confirm that the Gamow-Teller resonant state is populated with a log ft=3.9 and that there is very little mixing of this state with the background J=1 states. In contrast to previous measurements, the experimental method presented here is sensitive to very small admixtures at high excitation energy. Previously unobserved, weak beta-branches to levels in {sup 148}Tb are also reported.

  2. Amplification properties of Tb (III) green emission in polymeric waveguide doped with Tb–Al nanocluster

    Microsoft Academic Search

    K. Yamashita; N. Takeuchi; H. Taniguchi; S. Yuyama; K. Oe; N. Mibuka; A. Suzuki; H. Mataki

    2009-01-01

    This paper describes optical amplification properties in a polymeric waveguide doped with Tb–Al nanoclusters. The Tb–Al nanocluster is a promising fluorescent material for polymeric waveguides, which can be uniformly dispersed in polymer matrices while restraining the concentration quenching of Tb3+. Under the continuous optical pumping by 488nm laser light, optical amplification for the green emission of Tb3+ was achieved. The

  3. Magnetic reversal in Dy-doped DyF e2/YF e2 superlattice films

    NASA Astrophysics Data System (ADS)

    Stenning, G. B. G.; Bowden, G. J.; de Groot, P. A. J.; van der Laan, G.; Figueroa, A. I.; Bencok, P.; Steadman, P.; Hesjedal, T.

    2015-03-01

    Reversible magnetic exchange springs can be formed in the magnetically soft YF e2 layers of epitaxial DyF e2/YF e2 multilayer films. Here we show that the insertion of just two monolayers of DyF e2 , placed directly in the middle of the YF e2 layers, brings about substantial changes. Results are presented for a Dy-doped (110)-oriented [DyFe2(60Å) /YFe2(120 Å ) /DyFe2(8 Å ) /YFe2(120 Å ) ] 15 multilayer film, measured at 100 K in fields of up to ±10 T. Using bulk magnetometry, micromagnetic modeling, and Dy-specific x-ray magnetic circular dichroism, it is shown that Dy doping substantially increases the number of spin states available to the system. Altogether 12 distinct spring states are identified which bring additional complexity to the magnetic reversal process. In particular, the exchange springs are no longer reversible, exhibiting magnetic exchange-spring collapse. Full and partial magnetic loops are presented for fields applied along the in-plane easy [001] axis and the in-plane hard [1 ¯10 ] axis. In particular, it is demonstrated that exchange-spring collapse is sharpest when the field is applied along a hard in-plane [1 ¯10 ] axis.

  4. $s$-wave scattering lengths of the strongly dipolar bosons $^{162}$Dy and $^{164}$Dy

    E-print Network

    Tang, Yijun; Burdick, Nathaniel Q; Bohn, John L; Lev, Benjamin L

    2015-01-01

    We report the measurement of the triplet $s$-partial-wave scattering length $a$ of two bosonic isotopes of the highly magnetic element, dysprosium: $a=119(5)a_0$ for $^{162}$Dy and $a=89(4)a_0$ for $^{164}$Dy, where $a_0$ is the Bohr radius. The scattering lengths are determined by the cross-dimensional relaxation of ultracold gases of these Dy isotopes at temperatures above quantum degeneracy. In this temperature regime, the measured rethermalization dynamics can be compared to simulations of the Boltzmann equation using a direct-simulation Monte Carlo (DSMC) method employing the anisotropic differential scattering cross section of dipolar particles.

  5. Neutron detection with Gd/CdTe semiconductor detector

    NASA Astrophysics Data System (ADS)

    Miyake, Aki; Nishioka, Takahiro; Singh, Shailendra; Morii, Hisashi; Neo, Yoichiro; Mimura, Hidenori; Aoki, Toru

    2010-08-01

    Cadmium telluride (CdTe) detector has been used to detect thermal neutrons; along with gadolinium (Gd) used as a neutron converter. Simulation results show that the appropriate thickness of Gd film for CdTe detector is 25 ?m. The Gd/CdTe detector shows the 80 keV, 89 keV and 182 keV gamma ray emission peaks from 155Gd(n, ?)156Gd and 157Gd(n, ?)158Gd reactions.

  6. TB in Correctional Facilities Is a Public Health Concern

    MedlinePLUS

    ... CDC Features TB in Correctional Facilities is a Public Health Concern Recommend on Facebook Tweet Share Compartir Diagnosing ... the community with untreated TB present a serious public health concern. Figure 1 (larger view). TB Control in ...

  7. New cloth modeling for designing dyed patterns

    Microsoft Academic Search

    Yuki Morimoto; Kenji Ono

    2010-01-01

    We propose a novel cloth modeling method to simulate dyeing techniques. Morimoto et al. [2007] proposed a physics-based dyeing simulation method. To simulate dyeing techniques in conjunction with folded 3D cloth geometries, we developed a natural and intuitive method to generate cloth geometries. This method uses locally applied geometric operations for multiple dyed patterns on a cloth and a Voronoi

  8. The characterisation of treated and dyed hair

    Microsoft Academic Search

    J. T. Guthrie; A. Kazlauciunas; L. Rongong; S. Rush

    1995-01-01

    Studies have been undertaken to evaluate some of the factors that influence the dyeing of hair with dyes from the Arianor series. Dyed, bleached and untreated hair was examined by differential thermal analysis, optical microscopy, scanning electron microscopy, X-ray diffractometry and surface potential assessment. It has been found that marked changes in surface potentials arise on relatively mild treatment of

  9. Magnetism and magnetocaloric effect in (DyxGd5-x)Si2Ge2 (0?x?5) compounds

    NASA Astrophysics Data System (ADS)

    Nirmala, R.; Kundaliya, Darshan C.; Shinde, S. R.; Joshi, Amish G.; Morozkin, A. V.; Malik, S. K.

    2007-06-01

    Temperature and field dependence of magnetization of Dy-substituted Gd5Si2Ge2 compounds has been studied in the temperature range of 5-330K. The (DyxGd5-x)Si2Ge2 compounds with x =0.5, 1.5, 3.0, and 3.5 are found to order ferromagnetically with magnetic ordering temperature TC ranging between ˜270 and 80K. The Dy substitution in Gd5Si2Ge2 leads to a lowering of TC, an increase in coercivity, and also to a loss of the first order magnetic phase transition seen in the parent compound. The magnetic entropy change ?SM associated with the magnetic transition has been computed using the magnetization-field isotherm data. The maximum magnetic entropy changes of ˜8.8, 13.9, and 6.9J /kgK are obtained for x =0.5, 3.0, and 5 compounds, respectively, for a field change of 55kOe. The ?SM is spread around TC over a few tens of Kelvin and this feature makes these materials promising for possible use in Ericsson-cycle magnetic refrigerator applications.

  10. Mechanism of amorphous state formation, crystalline structure, and hyperfine interactions in DyMn6-xGe6Fex (0<=x<=6) alloys

    NASA Astrophysics Data System (ADS)

    ?niadecki, Z.; Mielniczuk, B.; Idzikowski, B.; Greneche, J.-M.; Rößler, U. K.

    2010-10-01

    Metallic glass formation is observed in rapidly quenched quaternary DyMn6-xGe6Fex (0?x?6) alloys. The easy formation of amorphous states competes with the nucleation of ternary 1:6:6 rare earth-transition metal-metal compounds DyMn6Ge6 and DyFe6Ge6. The ribbon shaped samples were quenched and investigated by x-ray diffraction, differential scanning calorimetry, and F57e Mössbauer spectrometry. Melt-spun alloys from the series of DyMn6-xGe6Fex with x=0, 2?x?3, and x=6 do not display an amorphous state but a crystalline chemically disordered structure similar to that of TbCu7- or TbFe6Sn6-type (space group P6/mmm). Amorphous samples exhibit two crystallization steps but there is no clear evidence for a glass transition effect in the calorimetric data. The Kissinger analysis was performed to calculate the effective activation energy Ea, which is equal to 345±20 kJ/mol for amorphous DyMn5.5Ge6Fe0.5 alloy. Mössbauer spectra at 77 and 300 K consist of either magnetic sextets or quadrupolar doublets for high and low Fe content, respectively. The features reflect the dilution of Fe on crystallographic sites and the subsequent increase in topological and chemical disorder when the Mn content increases. The Miedema's semiempirical model was used to calculate the formation enthalpies of amorphous alloys (?Hform). The calculated values are consistent with experimental results. The present model allows thus to explain the better glass forming ability for the compositions with high Mn content, where ?Hform is the most negative.

  11. Steric hindrances create a discrete linear Dy4 complex exhibiting SMM behaviour.

    PubMed

    Lin, Shuang-Yan; Zhao, Lang; Ke, Hongshan; Guo, Yun-Nan; Tang, Jinkui; Guo, Yang; Dou, Jianmin

    2012-03-21

    Two linear tetranuclear lanthanide complexes of general formula [Ln(4)(L)(2)(C(6)H(5)COO)(12)(MeOH)(4)], where HL = 2,6-bis((furan-2-ylmethylimino)methyl)-4-methylphenol, () and Ln(III) = Dy(III) (1) and Gd(III) (2), have been synthesized and characterized. The crystal structural analysis demonstrates that two Schiff-base ligands inhibit the growth of benzoate bridged 1D chains, leading to the isolation of discrete tetranuclear complexes due to their steric hindrances. Every Ln(III) ion is coordinated by eight donor atoms in a distorted bicapped trigonal-prismatic arrangement. Alternating current (ac) susceptibility measurements of complex 1 reveal a frequency- and temperature-dependent out-of-phase signal under zero dc field, typical of single-molecule magnet (SMM) behaviour with an anisotropic barrier ?(eff) = 17.2 K. PMID:22286075

  12. Spectroscopy of 153Gd and 157Gd using the (p,d ) reaction

    SciTech Connect

    Ross, T.J. [University of Richmond; Hughes, R.O. [University of Richmond; Allmond, James M [ORNL; Beausang, C.W. [University of Richmond; Angell, C.T. [Lawrence Berkeley National Laboratory (LBNL); Basunia, M.S. [Lawrence Berkeley National Laboratory (LBNL); Bleuel, D.L. [Lawrence Livermore National Laboratory (LLNL); Burke, J.T. [Lawrence Livermore National Laboratory (LLNL); Casperson, R.J. [Lawrence Livermore National Laboratory (LLNL); Escher, J.E. [Lawrence Livermore National Laboratory (LLNL); Fallon, P. [Lawrence Berkeley National Laboratory (LBNL); Hatarik, R. [Lawrence Berkeley National Laboratory (LBNL); Munson, J. [Lawrence Berkeley National Laboratory (LBNL); Paschalis, S. [Lawrence Berkeley National Laboratory (LBNL); Petri, M. [Lawrence Berkeley National Laboratory (LBNL); Phair, L. [Lawrence Berkeley National Laboratory (LBNL); Ressler, J.J. [Lawrence Livermore National Laboratory (LLNL); Scielzo, N.D. [Lawrence Livermore National Laboratory (LLNL)

    2014-01-01

    Low-spin single quasineutron levels in 153Gd and 157Gd have been studied following the 154Gd(p,d- )153Gd and 158Gd(p,d- )157Gd reactions. A combined Si telescope and high-purity germanium array was utilized, allowing d- and d- - coincidence measurements. Almost all of the established low-excitation-energy, low-spin structures were confirmed in both 153Gd and 157Gd. Several new levels and numerous new rays are observed in both nuclei, particularly for Ex > 1 MeV. Residual effects of a neutron subshell closure at N = 64 are observed in the form of a large excitation energy gap in the single quasineutron level schemes.

  13. New rare earth metal-rich indides RE14Ni 3In 3 ( RE=Sc, Y, Gd-Tm, Lu)—synthesis and crystal chemistry

    NASA Astrophysics Data System (ADS)

    Lukachuk, Mar'yana; Galadzhun, Yaroslav V.; Zaremba, Roman I.; Dzevenko, Mariya V.; Kalychak, Yaroslav M.; Zaremba, Vasyl I.; Rodewald, Ute Ch.; Pöttgen, Rainer

    2005-09-01

    The rare earth-nickel-indides RE14Ni 3In 3 ( RE=Sc, Y, Gd-Tm, Lu) were synthesized from the elements by arc-melting and subsequent annealing. The compounds were investigated on the basis of X-ray powder and single crystal data: Lu 14Co 2In 3 type, P4 2/ nmc, Z=4, a=888.1(1), c=2134.7(4), wR2=0.0653, 1381 F2 values, 63 variables for Sc 13.89Ni 3.66In 2.45; a=961.2(1), c=2316.2(5), wR2=0.0633, 1741 F2 values, 64 variables for Y 13.84Ni 3.19In 2.97; a=965.3(1), c=2330.5(5), wR2=0.0620, 1765 F2 values, 63 variables for Gd 14Ni 3.29In 2.71; a=956.8(1), c=2298.4(5), wR2=0.0829, 1707 F2 values, 64 variables for Tb 13.82Ni 3.36In 2.82; a=951.7(1), c=2289.0(5), wR2=0.0838, 1794 F2 values, 64 variables for Dy 13.60Ni 3.34In 3.06; a=948.53(7), c=2270.6(1), wR2=0.1137, 1191 F2 values, 64 variables for Ho 13.35Ni 3.17In 3.48; a=943.5(1), c=2269.1(5), wR2=0.0552, 1646 F2 values, 64 variables for Er 13.53Ni 3.14In 3.33; a=938.42(7), c=2250.8(1), wR2=0.1051, 1611 F2 values, 64 variables for Tm 13.47Ni 3.28In 3.25; a=937.3(1), c=2249.6(5), wR2=0.0692, 1604 F2 values, 64 variables for Tm 13.80Ni 3.49In 2.71; and a=933.4(1), c=2263.0(5), wR2=0.0709, 1603 F2 values, 64 variables for Lu 13.94Ni 3.07In 2.99. The RE14Ni 3In 3 indides show significant Ni/In mixing on the 4 c In1 site. Except the gadolinium compound, the RE14Ni 3In 3 intermetallics also reveal RE/In mixing on the 4 c RE1 site, leading to the refined compositions. Due to the high rare earth metal content, the seven crystallographically independent RE sites have between 9 and 10 nearest RE neighbors. The RE14Ni 3In 3 structures can be described as a complex intergrowth of rare earth-based polyhedra. Both nickel sites have a distorted trigonal-prismatic rare earth coordination. An interesting feature is the In2-In2 dumb-bell at an In2-In2 distance of 304 pm (for Gd 14Ni 3.29In 2.71). The crystal chemical peculiarities of the RE14Ni 3In 3 indides are briefly discussed.

  14. Elastic and magnetoelastic properties of polycrystalline rare-earth-iron Laves compounds

    Microsoft Academic Search

    H. Klimker; M. Rosen; M. P. Dariel; U. Atzmony

    1974-01-01

    Ultrasonic-sound velocity measurements have been used in order to determine the elastic moduli of polycrystalline rare-earth-iron Laves compounds RFe2 (R=Ce, Gd, Tb, Dy, Dy, Ho, Er) and YFe2 between 4.2 and 300 K. The DeltaE effect of these compounds was determined in external magnetic field up to 25 kOe. No saturation was reached at this field in DyFe2 and TbFe2.

  15. Stability of multiferroicity against Dy/Mn off-stoichiometry in DyMnO{sub 3}

    SciTech Connect

    Wang, J. X.; Liu, M. F.; Zhao, Z. Y.; Yan, Z. B.; Liu, J.-M., E-mail: liujm@nju.edu.cn [Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China)

    2014-05-07

    We investigate the effects of slight Dy/Mn off-stoichiometry on the multiferroic behaviors of DyMnO{sub 3} (Dy{sub 1?x}Mn{sub 1+x}O{sub 3}). It is revealed that the distorted lattice structure and ferroelectric property exhibit higher stability against the Mn deficiency than the Dy deficiency. Since the electric polarization includes the contributions from the Mn-Mn and Dy-Mn interactions, the measured polarization exhibits different dependence on the Mn deficiency from that on the Dy deficiency. The present work suggests that the Dy/Mn off-stoichiometry is detrimental to the ferroelectricity, owing to the modulated spin interactions and reshuffled spin frustration.

  16. A comparative study of magnetic behaviors in TbNi{sub 2}, TbMn{sub 2} and TbNi{sub 2}Mn

    SciTech Connect

    Wang, J. L., E-mail: jianli@uow.edu.au [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Bragg Institute, ANSTO, Lucas Heights, NSW 2234 (Australia); Md Din, M. F.; Hong, F.; Cheng, Z. X.; Dou, S. X. [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Kennedy, S. J.; Studer, A. J. [Bragg Institute, ANSTO, Lucas Heights, NSW 2234 (Australia); Campbell, S. J. [School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, Canberra, ACT 2600 (Australia); Wu, G. H. [Institute of Physics, Chinese Academy of Science, Beijing 100190 (China)

    2014-05-07

    All TbNi{sub 2}, TbMn{sub 2}, and TbNi{sub 2}Mn compounds exhibit the cubic Laves phase with AB{sub 2}-type structure in spite of the fact that the ratio of the Tb to transition-metal components in TbNi{sub 2}Mn is 1:3. Rietveld refinement indicates that in TbNi{sub 2}Mn the Mn atoms are distributed on both the A (8a) and B (16d) sites. The values of the lattice constants were measured to be a?=?14.348?Å (space group F-43?m), 7.618?Å, and 7.158?Å (space group Fd-3?m) for TbNi{sub 2}, TbMn{sub 2}, and TbNi{sub 2}Mn, respectively. The magnetic transition temperatures T{sub C} were found to be T{sub C}?=?38?K and T{sub C}?=?148?K for TbNi{sub 2} and TbNi{sub 2}Mn, respectively, while two magnetic phase transitions are detected for TbMn{sub 2} at T{sub 1}?=?20?K and T{sub 2}?=?49?K. Clear magnetic history effects in a low magnetic field are observed in TbMn{sub 2} and TbNi{sub 2}Mn. The magnetic entropy changes have been obtained.

  17. A comparative study of magnetic behaviors in TbNi2, TbMn2 and TbNi2Mn

    NASA Astrophysics Data System (ADS)

    Wang, J. L.; Md Din, M. F.; Kennedy, S. J.; Hong, F.; Campbell, S. J.; Studer, A. J.; Wu, G. H.; Cheng, Z. X.; Dou, S. X.

    2014-05-01

    All TbNi2, TbMn2, and TbNi2Mn compounds exhibit the cubic Laves phase with AB2-type structure in spite of the fact that the ratio of the Tb to transition-metal components in TbNi2Mn is 1:3. Rietveld refinement indicates that in TbNi2Mn the Mn atoms are distributed on both the A (8a) and B (16d) sites. The values of the lattice constants were measured to be a = 14.348 Å (space group F-43 m), 7.618 Å, and 7.158 Å (space group Fd-3 m) for TbNi2, TbMn2, and TbNi2Mn, respectively. The magnetic transition temperatures TC were found to be TC = 38 K and TC = 148 K for TbNi2 and TbNi2Mn, respectively, while two magnetic phase transitions are detected for TbMn2 at T1 = 20 K and T2 = 49 K. Clear magnetic history effects in a low magnetic field are observed in TbMn2 and TbNi2Mn. The magnetic entropy changes have been obtained.

  18. Stellar neutron capture cross sections of the Gd isotopes

    Microsoft Academic Search

    K. Wisshak; F. Voss; F. Käppeler; L. Kazakov; N. Kornilov; G. Reffo

    1995-01-01

    The neutron capture cross sections of 152Gd, 154Gd, 155Gd, 156Gd, 157Gd, and 158Gd were measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p,n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4pi Barium Fluoride

  19. Crystal and magnetic structure of the R15Si9C compounds (R = Ho, Er, Tb)

    NASA Astrophysics Data System (ADS)

    Ritter, C.; Wrubl, F.; Hill, A. H.; Pani, M.; Manfrinetti, P.

    2011-07-01

    The synthesis of the new compounds R15Si9C with R = Sm, Gd-Er, Y and R15Ge9C with R = Ce, Pr and Nd has been recently reported; these compounds crystallize in the hexagonal La15Ge9Fe structure type, hP50-P63mc, Z = 2 (ordered superstructure of La5Ge3 (Mn5Si3-type, hP 16-P63/mcm, Z = 2)). Here we report the results of a neutron diffraction investigation that we have performed to study the crystal and magnetic structures of the R15Si9C compounds with R = Tb, Ho and Er. All three compounds see the establishment of commensurate magnetic order with a predominantly ferromagnetic interaction. Details of mixed antiferro-ferromagnetic spin arrangements (? = [000]) (for Tb15Si9C and Ho15Si9C) or of purely ferromagnetic ordering (Er15Si9C), and of their temperature dependence, are given and linked to the different coordination of the four dissimilar rare earth sites. In the Tb and Ho compounds the thermal evolution of the magnetic moment values strongly differs between the different R sites. The position occupied by the principal carbon has been determined (Wyckoff site 2b) and the existence of a second position available for the interstitial carbon (Wyckoff site 2a) has been revealed for R = Ho, Tb. Moreover, in the Tb and Ho compounds the magnetic moment value of the rare earth site R4, surrounding the second interstitial carbon site, is strongly reduced if compared to the value on the other rare earth sites. The magnetic transition temperatures of all three compounds, i.e. TC = 130, 43 and 45 K for Tb15Si9C, Ho15Si9C and Er15Si9C, are remarkably high compared to those of the parent R5Si3 compounds. The magnetic behaviour of the partly filled Tb5Si3C0.25 is reported.

  20. Thermochromism and fluorescence in dyed PEO films

    NASA Astrophysics Data System (ADS)

    Kamath, Archana; S, Raghu; V, Mini; C, Sharanappa; H, Devendrappa

    2015-06-01

    The optical absorbance spectra of solution casted pure & methyl blue (MB) dyed polyethylene oxide (PEO) films were recorded in a wavelength range from 190-1100nm at different temperatures. The absorbance was found to increases with increasing temperature. Fluorescence micrographs confirmed the interaction between polymer and dye and also revealed decreased crystallinity of the sample. Fluorescence quantum yield has been calculated with the help of fluorescence spectra.

  1. Post-Doctoral Research Fellowship TB immunology

    E-print Network

    Wolfe, Kenneth H.

    Post-Doctoral Research Fellowship­ TB immunology Applications are invited from qualified post-doctoral researchers to study M. tuberculosis (Mtb) biology and the immune response to tuberculosis. The position

  2. Immunomodulation by vitamin D: implications for TB

    PubMed Central

    Chun, Rene F; Adams, John S; Hewison, Martin

    2011-01-01

    TB remains a major cause of mortality throughout the world. Low vitamin D status has been linked to increased risk of TB and other immune disorders. These observations suggest a role for vitamin D as a modulator of normal human immune function. This article will detail the cellular and molecular mechanisms by which vitamin D regulates the immune system and how vitamin D insufficiency may lead to immune dysregulation. The importance of vitamin D bioavailability as a mechanism for defining the immunomodulatory actions of vitamin D and its impact on TB will also be discussed. The overall aim will be to provide a fresh perspective on the potential benefits of vitamin D supplementation in the prevention and treatment of TB. PMID:22046197

  3. Multidrug-Resistant Tuberculosis (MDR TB)

    MedlinePLUS

    ... percent of such cases in 2011. 5 The World Health Organization estimates that there were about 310,000 cases ... Centers for Disease Control and Prevention and the World Health Organization reported the existence of XDR TB in 17 ...

  4. Na3DyCl6

    PubMed Central

    Schurz, Christian M.; Meyer, Gerd; Schleid, Thomas

    2011-01-01

    Single crystals of the title compound, tris­odium hexa­chloridodysprosate, Na3DyCl6, were obtained as a by-product of synthesis using dysprosium(III) chloride and sodium chloride among others. The monoclinic structure with its typical ? angle close to 90° [90.823 (4)°] is isotypic with the mineral cryolite (Na3AlF6) and the high-temperature structure of the Na3 MCl6 series, with M = Eu–Lu, Y and Sc. The isolated, almost perfect [DyCl6]3? octa­hedra are inter­connected via two crystallographically different Na+ cations: while one Na+ resides on centres of symmetry (as well as Dy3+) and also builds almost perfect, isolated [NaCl6]5? octa­hedra, the other Na+ is surrounded by seven chloride anions forming a distorted [NaCl7]6? trigonal prism with just one cap as close secondary contact. PMID:21754259

  5. GD2-targeted immunotherapy and radioimmunotherapy.

    PubMed

    Dobrenkov, Konstantin; Cheung, Nai-Kong V

    2014-10-01

    Ganglioside GD2 is a tumor-associated surface antigen found in a broad spectrum of human cancers and stem cells. They include pediatric embryonal tumors (neuroblastoma, retinoblastoma, brain tumors, osteosarcoma, Ewing sarcoma, rhabdomyosarcoma), as well as adult cancers (small cell lung cancer, melanoma, soft tissue sarcomas). Because of its restricted normal tissue distribution, GD2 has been proven safe for antibody targeting. Anti-GD2 antibody is now incorporated into the standard of care for the treatment of high-risk metastatic neuroblastoma. Building on this experience, novel combinations of antibodies, cytokines, cells, and genetically engineered products all directed at GD2 are rapidly moving into the clinic. In this review, past and present immunotherapy trials directed at GD2 will be summarized, highlighting the lessons learned and the future directions. PMID:25440605

  6. Magnetic Structure of Dy3+ in Hexagonal Multiferroic DyMnO3

    SciTech Connect

    S.Nandi; A. Kreyssi; J.Q. Yan; M.D. Vannette; J.C. Lang; L. Tan; J.W. Kim; R. Prozorov; T.A. Lograsso; R.J. McQueeney; A.I. Goldman

    2008-08-22

    Element specific x-ray resonant magnetic scattering (XRMS) investigations were undertaken to determine the magnetic structure of the multiferroic compound, hexagonal DyMnO{sub 3}. In the temperature range from 68 K down to 8 K the Dy{sup 3+} moments are aligned and antiferromagnetically correlated in the c direction according to the magnetic representation {Lambda}{sub 3}. The temperature dependence of the observed intensity can be modeled assuming the splitting of ground-state doublet crystal-field levels of Dy{sup 3+} by the exchange field of Mn{sup 3+}. XRMS together with magnetization measurements indicate that the magnetic representation is {Lambda}{sub 2}below 8 K.

  7. Decay properties of long-lived isomers in the odd-odd N=81 nucleus Tb146 compared to the Ho148 and Tm150 nuclei

    NASA Astrophysics Data System (ADS)

    Kownacki, J.; Droste, Ch.; Morek, T.; Ruchowska, E.; Lieder, R. M.; Kisieli?ski, M.; Kowalczyk, M.; Andrzejewski, J.; Perkowski, J.; Napiorkowski, P. J.; Wrzosek-Lipska, K.; Zieli?ska, M.; Kordyasz, A.; Korman, A.; Hady?ska-Kl?k, K.; Grodner, E.; Mierzejewski, J.; Srebrny, J.

    2011-02-01

    Excited states of the Tb146 nucleus have been studied using ?-ray and electron spectroscopy in off-beam and in-beam modes following Sn112(Ar40,3n3p) reaction with the use of the OSIRIS-II, HPGe detector array and the conversion electron spectrometer. The multipolarity of the 343 keV transition deexciting the (7-) level in Tb146 shows mainly an E2 nature and the first excited state above the 23 s isomer is assigned as a (5-,6-) state. The log ft values have been deduced for 11 ?+/EC transitions populating excited states in Gd146. The systematic behavior of spins and parities of the long-lived levels at 0+x keV and the first excited states above them in the N=81 isotones Tb146, Ho148, and Tm150 is discussed.

  8. Dysprosium ( 165 Dy) hydroxide macroaggregates for radiation synovectomy — animal studies

    Microsoft Academic Search

    Ashley McLaren; Eric Hetherington; Des Maddalena; Graeme Snowdon

    1990-01-01

    This paper reports the development of a new chemical formulation, Dy-HMA, to utilise the advantages of dysprosium 165 in radiation synovectomy of certain forms of arthritis. Dy-HMA is a sterile suspension of dysprosium hydroxide macroaggregates (approximately 6 mg Dy\\/ml) in saline with the majority of particles in the 3–5 µm range. The absence of ferric hydroxide and a higher concentration

  9. Three-micron laser action in Dy3+

    Microsoft Academic Search

    B. M. Antipenko; A. L. Ashkalunin; Artur A. Mak; B. V. Sinitsyn; Yu V. Tomashevich; G. S. Shakhkalamyan

    1980-01-01

    An experimental investigation was made of laser action in Dy3+ ions in an LaF3 crystal excited by neodymium laser radiation. It is shown by calculation that neodymium laser radiation may be converted to the three-micron range with an efficiency of the order of 10% using Y3Al5O12:Yb3+:Dy3+ and BaY2F8:Dy3+ media. Bibtex entry for this abstract Preferred format for this abstract (see

  10. NON-COLLECTIVE HIGH-SPIN STATES IN 148Dy

    E-print Network

    Dines, E.L.

    2010-01-01

    on Dy, involving linear polarization and conversion electronpolarization of the T-rays(in addition to their directional correlation), or if one observed the directional correlations between conversion

  11. Long range ordered magnetic and atomic structures of the quasicrystal approximant in the Tb-Au-Si system.

    PubMed

    Gebresenbut, Girma; Andersson, Mikael Svante; Beran, P?emysl; Manuel, Pascal; Nordblad, Per; Sahlberg, Martin; Gomez, Cesar Pay

    2014-08-13

    The atomic and magnetic structure of the 1/1 Tb(14)Au(70)Si(16) quasicrystal approximant has been solved by combining x-ray and neutron diffraction data. The atomic structure is classified as a Tsai-type 1/1 approximant with certain structural deviations from the prototype structures; there are additional atomic positions in the so-called cubic interstices as well as in the cluster centers. The magnetic property and neutron diffraction measurements indicate the magnetic structure to be ferrimagnetic-like below 9 K in contrast to the related Gd(14)Au(70)Si(16) structure that is reported to be purely ferromagnetic. PMID:25055216

  12. Long range ordered magnetic and atomic structures of the quasicrystal approximant in the Tb-Au-Si system

    NASA Astrophysics Data System (ADS)

    Gebresenbut, Girma; Svante Andersson, Mikael; Beran, P?emysl; Manuel, Pascal; Nordblad, Per; Sahlberg, Martin; Pay Gomez, Cesar

    2014-08-01

    The atomic and magnetic structure of the 1/1 Tb(14)Au(70)Si(16) quasicrystal approximant has been solved by combining x-ray and neutron diffraction data. The atomic structure is classified as a Tsai-type 1/1 approximant with certain structural deviations from the prototype structures; there are additional atomic positions in the so-called cubic interstices as well as in the cluster centers. The magnetic property and neutron diffraction measurements indicate the magnetic structure to be ferrimagnetic-like below 9 K in contrast to the related Gd(14)Au(70)Si(16) structure that is reported to be purely ferromagnetic.

  13. Macrocyclic Gd(3+) Complexes with Pendant Crown Ethers Designed for Binding Zwitterionic Neurotransmitters.

    PubMed

    Oukhatar, Fatima; Meudal, Hervé; Landon, Céline; Logothetis, Nikos K; Platas-Iglesias, Carlos; Angelovski, Goran; Tóth, Éva

    2015-07-27

    A series of Gd(3+) complexes exhibiting a relaxometric response to zwitterionic amino acid neurotransmitters was synthesized. The design concept involves ditopic interactions 1)?between a positively charged and coordinatively unsaturated Gd(3+) chelate and the carboxylate group of the neurotransmitters and 2)?between an azacrown ether appended to the chelate and the amino group of the neurotransmitters. The chelates differ in the nature and length of the linker connecting the cyclen-type macrocycle that binds the Ln(3+) ion and the crown ether. The complexes are monohydrated, but they exhibit high proton relaxivities (up to 7.7?mM(-1) ?s(-1) at 60?MHz, 310?K) due to slow molecular tumbling. The formation of ternary complexes with neurotransmitters was monitored by (1) H relaxometric titrations of the Gd(3+) complexes and by luminescence measurements on the Eu(3+) and Tb(3+) analogues at pH?7.4. The remarkable relaxivity decrease (?80?%) observed on neurotransmitter binding is related to the decrease in the hydration number, as evidenced by luminescence lifetime measurements on the Eu(3+) complexes. These complexes show affinity for amino acid neurotransmitters in the millimolar range, which can be suited to imaging concentrations of synaptically released neurotransmitters. They display good selectivity over non-amino acid neurotransmitters (acetylcholine, serotonin, and noradrenaline) and hydrogenphosphate, but selectivity over hydrogencarbonate was not achieved. PMID:26118946

  14. Favored neutron excitations in superdeformed 147Gd

    NASA Astrophysics Data System (ADS)

    Theisen, Ch.; Khadiri, N.; Vivien, J. P.; Ragnarsson, I.; Beausang, C. W.; Beck, F. A.; Belier, G.; Byrski, T.; Curien, D.; de France, G.; Disdier, D.; Duchêne, G.; Finck, Ch.; Flibotte, S.; Gall, B.; Haas, B.; Hanine, H.; Herskind, B.; Kharraja, B.; Merdinger, J. C.; Nourreddine, A.; Nyakó, B. M.; Perez, G. E.; Prévost, D.; Stezowski, O.; Rauch, V.; Rigollet, C.; Savajols, H.; Sharpey-Schafer, J.; Twin, P. J.; Wei, L.; Zuber, K.

    1996-12-01

    Four new superdeformed (SD) bands have been observed in 147Gd using the EUROGAM II spectrometer. By comparison with 146,148,149Gd SD bands, we use the effective alignment to assign excited band configurations, with the support of the Nilsson-Strutinsky cranking formalism. The effect of the crossing of the [642]5/2 and [651]1/2 neutron orbitals lying just below the magic N=86 SD shell gap has been investigated for the 146,147,148Gd bands. Evidence for the [411]1/2 orbital is also given.

  15. Magnetic structure of dysprosium in epitaxial Dy films and in Dy/Er superlattices

    SciTech Connect

    Dumesnil, K.; Dufour, C.; Mangin, P.; Marchal, G. [Laboratoire Metallurgie Physique et Science des Materiaux (URA CNRS 155), Universite Henri Poincare-Nancy I, BP 239, 54506 Vandoeuvre les Nancy cedex (France)] [Laboratoire Metallurgie Physique et Science des Materiaux (URA CNRS 155), Universite Henri Poincare-Nancy I, BP 239, 54506 Vandoeuvre les Nancy cedex (France); Hennion, M. [Laboratoire Leon Brillouin, Centre d`Etudes Atomiques de Saclay, 91191 Gif-sur-Yvette cedex (France)] [Laboratoire Leon Brillouin, Centre d`Etudes Atomiques de Saclay, 91191 Gif-sur-Yvette cedex (France)

    1996-09-01

    We present a magnetization and neutron-diffraction study of the basal plane magnetic structure of Dy epitaxial films and Dy/Er superlattices. The thermal evolution of the magnetic phases, the stability of the helical phase under a magnetic field, the thermal variation of the dysprosium in-plane and {ital c} parameters, and of the dysprosium turn angle are successively shown. In Dy/Er superlattices, the dysprosium helix propagates coherently through paramagnetic erbium; at low temperature, individual dysprosium layers undergo a ferromagnetic transition and are coupled antiferromagnetically to each other for erbium layers thicknesses larger than 20 A. In dysprosium films, as expected from the epitaxy effect, the Curie temperature of dysprosium is reduced if dysprosium is grown on yttrium and increased if it is grown on erbium, whereas it is unexpectedly close to the bulk value in Dy/Er superlattices. This amazing value of the Curie temperature in superlattices is correlated to two main experimentally observed effects: (i) the magnetoelastic driving force is reduced compared to bulk dysprosium because of the clamped {gamma} distortion; (ii) the difference between the exchange energies in the helical and the ferromagnetic phases is increased compared to the bulk value. {copyright} {ital 1996 The American Physical Society.}

  16. Slow magnetic relaxation in novel Dy4 and Dy8 compounds.

    PubMed

    Yang, Pei-Pei; Gao, Xi-Feng; Song, Hai-Bin; Zhang, Sai; Mei, Xue-Lan; Li, Li-Cun; Liao, Dai-Zheng

    2011-02-01

    Two novel dysprosium(III) clusters have been prepared and structurally characterized. One has a tetranuclear core with a rare zigzag arrangement, and the other is an unprecedented octanuclear cluster with six triangular Dy(3) units sharing vertices. Both dysprosium(III) clusters possess frequency-dependent on alternating-current magnetic susceptibilities, indicating possible single-molecule magnet behavior. PMID:21186821

  17. 155Gd Mössbauer measurements on the ceramic superconductor GdBa 2Cu 3O 7

    NASA Astrophysics Data System (ADS)

    Smit, H. H. A.; Dirken, M. W.; Thiel, R. C.; de Jongh, L. J.

    1987-11-01

    155Gd Mössbauer effect measurements have been performed on GdBa 2Cu 3O 7 both in the superconducting orthorhombic and in the semiconducting tetragonal phase. The observed isomer shifts are similar to those found in insulating Gd-transition metal-oxides, indicating that there is no conduction electron density within the Gd layers Below the temperature at which the specific heat shows a sharp peak both phases show magnetic ordering. The Gd moment is found to be parallel to the c-axis. Dipolar calculations show that the dipolar field at the Cu sites is negligibly small and that the magnetic ordering of the Gd moments is probably of the 2-d Ising type.

  18. Determination of Gd concentration profile in UO2-Gd2O3 fuel pellets

    E-print Network

    Tobia, D; Milano, J; Butera, A; Kempf, R; Bianchi, L; Kaufmann, F

    2014-01-01

    A transversal mapping of the Gd concentration was measured in UO2-Gd2O3 nuclear fuel pellets by electron paramagnetic resonance spectroscopy (EPR). The quantification was made from the comparison with a Gd2O3 reference sample. The nominal concentration in the pellets is UO2: 7.5 % Gd2O3. A concentration gradient was found, which indicates that the Gd2O3 amount diminishes towards the edges of the pellets. The concentration varies from (9.3 +/- 0.5)% in the center to (5.8 +/- 0.3)% in one of the edges. The method was found to be particularly suitable for the precise mapping of the distribution of Gd3+ ions in the UO2 matrix.

  19. TB drug development: immunology at the table.

    PubMed

    Nathan, Carl; Barry, Clifton E

    2015-03-01

    Our understanding of the host-pathogen relationship in tuberculosis (TB) can help guide drug discovery in at least two ways. First, the recognition that host immunopathology affects lesional TB drug distribution means that pharmacokinetic evaluation of drug candidates needs to move beyond measurements of drug levels in blood, whole lungs, or alveolar epithelial lining fluid to include measurements in specific types of lesions. Second, by restricting the replication of M. tuberculosis (Mtb) subpopulations in latent TB infection and in active disease, the host immune response puts Mtb into a state associated with phenotypic tolerance to TB drugs selected for their activity against replicating Mtb. This has spurred a major effort to conduct high throughput screens in vitro for compounds that can kill Mtb when it is replicating slowly if at all. Each condition used in vitro to slow Mtb's replication and thereby model the phenotypically drug-tolerant state has advantages and disadvantages. Lead candidates emerging from such in vitro studies face daunting challenges in the design of proof-of-concept studies in animal models. Moreover, some non-replicating subpopulations of Mtb fail to resume replication when plated on agar, although their viability is demonstrable by other means. There is as yet no widely replicated assay in which to screen compounds for their ability to kill this 'viable but non-culturable' subpopulation. Despite these hurdles, drugs that can kill slowly replicating or non-replicating Mtb may offer our best hope for treatment-shortening combination chemotherapy of TB. PMID:25703568

  20. Constraint on 0??? matrix elements from a novel decay channel of the scissors mode: the case of 154Gd.

    PubMed

    Beller, J; Pietralla, N; Barea, J; Elvers, M; Endres, J; Fransen, C; Kotila, J; Möller, O; Richter, A; Rodríguez, T R; Romig, C; Savran, D; Scheck, M; Schnorrenberger, L; Sonnabend, K; Werner, V; Zilges, A; Zweidinger, M

    2013-10-25

    The nucleus (154)Gd is located in a region of the nuclear chart where rapid changes of nuclear deformation occur as a function of particle number. It was investigated using a combination of ?-ray scattering experiments and a ??-coincidence study following electron capture decay of (154)Tb(m). A novel decay channel from the scissors mode to the first excited 0(+) state was observed. Its transition strength was determined to B(M1;1(sc)(+)?0(2)(+))=0.031(4)?(N)(2). The properties of the scissors mode of (154)Gd imply a much larger matrix element than previously thought for the neutrinoless double-? decay to the 0(2)(+) state in such a shape-transitional region. Theory indicates an even larger effect for (150)Nd. PMID:24206482

  1. GAPS IN THE GD-1 STAR STREAM

    SciTech Connect

    Carlberg, R. G. [Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H4 (Canada); Grillmair, C. J., E-mail: carlberg@astro.utoronto.ca, E-mail: carl@ipac.caltech.edu [Spitzer Science Center, 1200 East California Boulevard, Pasadena, CA 91125 (United States)

    2013-05-10

    GD-1 is a long, thin, Milky Way star stream that has readily visible density variations along its length. We quantify the locations, sizes, and statistical significance of the density structure, i.e., gaps, using a set of scaled filters. The shapes of the filters are based on the gaps that develop in simulations of dark matter sub-halos crossing a star stream. The high Galactic latitude 8.4 kpc long segment of GD-1 that we examine has 8 {+-} 3 gaps of 99% significance or greater, with the error estimated on the basis of tests of the gap-filtering technique. The cumulative distribution of gaps more than three times the width of the stream is in good agreement with predictions for dark matter sub-halo encounters with cold star streams. The number of gaps narrower than three times the width of the GD-1 stream falls well below the cold stream prediction which is taken into account for the gap creation rate integrated over all sizes. Simple warm stream simulations scaled to GD-1 show that the falloff in gaps is expected for sub-halos below a mass of 10{sup 6} M{sub Sun }. The GD-1 gaps requires 100 sub-halos >10{sup 6} M{sub Sun} within 30 kpc, the apocenter of GD-1 orbit. These results are consistent with LCDM sub-halo predictions but further improvements in stream signal-to-noise and gap modeling will be welcome.

  2. TAIMA (Stop) TB: The Impact of a Multifaceted TB Awareness and Door-to-Door Campaign in Residential Areas of High Risk for TB in Iqaluit, Nunavut

    PubMed Central

    Alvarez, Gonzalo G.; VanDyk, Deborah D.; Aaron, Shawn D.; Cameron, D. William; Davies, Naomi; Stephen, Natasha; Mallick, Ranjeeta; Momoli, Franco; Moreau, Katherine; Obed, Natan; Baikie, Maureen; Osborne, Geraldine

    2014-01-01

    Background The incidence rate of active tuberculosis (TB) disease in the Canadian Territory of Nunavut has shown a rising trend over the past 10 years. In 2010 it was 60 times greater than the national incidence rate. The objective of the Taima (translates to “stop” in Inuktitut) TB study was to implement and evaluate a public health campaign to enhance existing TB prevention efforts in Nunavut. Methods A TB awareness campaign followed by a door-to-door screening campaign was carried out in Iqaluit, Nunavut. The aim of the campaign was to raise awareness about TB, and to provide in-home screening and treatment for people living in residential areas at high risk for TB. Screening was based on geographic location rather than on individual risk factors. Results During the general awareness campaign an increase in the number of people who requested TB testing at the local public health clinic was observed. However, this increase was not sustained following cessation of the awareness campaign. Targeted TB screening in high risk residential areas in Iqaluit resulted in 224 individuals having TSTs read, and detection of 42 previously unidentified cases of latent TB, (overall yield of 18.8% or number needed to screen?=?5.3). These cases of latent TB infection (LTBI) were extra cases that had not been picked up by traditional screening practices (34% relative increase within the community). This resulted in a 33% relative increase in the completion of LTBI treatment within the community. The program directly and indirectly identified 5/17 new cases of active TB disease in Iqaluit during the study period (29.5% of all incident cases). Conclusions While contact tracing investigations remain a cornerstone of TB prevention, additional awareness, screening, and treatment programs like Taima TB may contribute to the successful control of TB in Aboriginal communities. PMID:25033320

  3. HIV-1 and the immune response to TB

    PubMed Central

    Walker, Naomi F; Meintjes, Graeme; Wilkinson, Robert J

    2013-01-01

    TB causes 1.4 million deaths annually. HIV-1 infection is the strongest risk factor for TB. The characteristic immunological effect of HIV is on CD4 cell count. However, the risk of TB is elevated in HIV-1 infected individuals even in the first few years after HIV acquisition and also after CD4 cell counts are restored with antiretroviral therapy. In this review, we examine features of the immune response to TB and how this is affected by HIV-1 infection and vice versa. We discuss how the immunology of HIV–TB coinfection impacts on the clinical presentation and diagnosis of TB, and how antiretroviral therapy affects the immune response to TB, including the development of TB immune reconstitution inflammatory syndrome. We highlight important areas of uncertainty and future research needs. PMID:23653664

  4. Extensively drug resistant tuberculosis (XDR-TB): A potential threat

    PubMed Central

    Marwar, Anaga; Shaker, Ivvala Anand; Palawan, Hemraz; Nanadal; Ranjith, M. S.; GokulShankar

    2010-01-01

    Emergence of extensively drug resistant tuberculosis (XDR-TB) has been reported by more than 55 countries. XDR-TB is considered as untreatable and highly fatal disease. In developing countries like India, number of cases of multi-drug resistant tuberculosis (MDR-TB) and XDR-TB are increasing. Emergence of resistance to Isoniazid and Rifampicin, the two most effective and well tolerated agents, coupled with resistance to second line agents pose limited treatment options for XDR-TB. The present minireview provides information about the seriousness of XDR-TB and the drugs available for its treatment. Although considered a fatal disorder, judicious use of combination of drugs, retaining their antimycobacterial activity, can improve the clinical outcome of XDR-TB. Only such an approach can provide some hope for the patients of XDR-TB PMID:24825999

  5. Spectroscopic study of Dy 3+ and Dy 3+/Yb 3+ ions co-doped in barium fluoroborate glass

    NASA Astrophysics Data System (ADS)

    Dwivedi, Y.; Rai, S. B.

    2009-08-01

    Dy 3+ and Dy 3+/Yb 3+ co-doped barium fluoroborate glasses have been synthesized and their luminescence properties have been monitored under UV (355 nm) and NIR (976 nm) excitations, respectively. Absorption spectra of the two samples were recorded and Judd-Ofelt intensity parameters and other radiative parameters were calculated and compared. Dy 3+ doped sample yields strong yellowish white emission under 355 nm excitation. No emission is observed with 976 nm excitation. The Dy 3+/Yb 3+ ions co-doped sample on the other hand gives weak upconversion emission in blue, yellow and red regions on 976 nm excitation via energy transfer process from Yb 3+ to Dy 3+ ions from other level. An involvement of three photons has been noted for these emissions. Decay curve for different transitions of these samples have also been recorded and the lifetime of the corresponding levels involved are calculated.

  6. Magnetostriction of growth textured Tb-Zn alloys

    Microsoft Academic Search

    D. W. Delaney; T. A. Lograsso

    1999-01-01

    The magnetostrictive performance of aligned microstructural composites of Tb-Zn alloys were experimentally tested at 77K under compressive loads ranging from approximately 0-50 MPa and applied magnetic field up to 2000 Oe. Tb-8a\\/oZn, Tb-42a\\/oZn and the eutectic composition of Tb-27.8a\\/oZn were all directionally solidified to prepare aligned, textured microstructures. The eutectic sample grew with lamellar plates with the magnetically hard axes

  7. Magnetostriction of growth textured Tb–Zn alloys

    Microsoft Academic Search

    D. W Delaney; T. A Lograsso

    1999-01-01

    The magnetostrictive performance of aligned microstructural composites of Tb–Zn alloys were experimentally tested at 77K under compressive loads ranging from approximately 0–50 MPa and applied magnetic field up to 2000 Oe. Tb-8a\\/oZn, Tb-42a\\/oZn and the eutectic composition of Tb-27.8a\\/oZn were all directionally solidified to prepare aligned, textured microstructures. The eutectic sample grew with lamellar plates with the magnetically hard axes

  8. Electronic structures of Gd overlayers and Gd silicide nanowires on Si(100)

    NASA Astrophysics Data System (ADS)

    Kim, Y. K.

    2004-03-01

    Angle-resolved ultraviolet photoemission spectroscopy (ARUPS) and low-energy electron diffraction (LEED) are employed to investigate Gd-induced reconstructions and Gd silicide nanowires on Si(100) at the substrate temperature of RT - 600 ^rcC. LEED observations indicate that a submonolayer of Gd can induce a 1×4 phase at about 200 ^rcC, in addition to an apparent 2×7 phase at 300 - 600 ^rcC. At around 600 ^rcC, there are streaks along ×1 directions in LEED. It suggests the formation of Gd silicide nanowires. ARUPS observations indicate a surface state at the very near Ef and a weak metallic character for the 1×4 phase. For the 2×7 phase, two filled surface states at 0.3 and 0.8 eV(S1 and S2) are observed and are explained from the recent structure model, which consists of two alternating Gd chains with 3a_Si and 4a_Si in width, respectively. At around 600 ^rcC, two additional features at 0.1 and 1.1 eV (S1' and S2') are found to grow in intensity with increasing Gd coverages. It suggests that S1' and S2' are due to the Gd silicide nanowires on the Si surface. This result is consistent with the recent STM observations of the metallic Gd silicide nanowires on Si(100).

  9. Magnetoelastic contribution to perpendicular anisotropy in amorphous Gd-Co and Gd-Fe films

    Microsoft Academic Search

    S. Tsunashima; H. Takagi; K. Kamegaki; T. Fujii; S. Uchiyama

    1978-01-01

    The magnetoelastic contribution to the perpendicular anisotropy in rf sputtered amorphous Gd-Co and Gd-Fe films was investigated by the following three experiments: (1) Measurement of the magnetoelastic coupling energy, (2) measurement of the internal planar stress, and (3) the evaluation of the anisotropy due to the substrate constraint. In these experiments it was found that the magnetoelastic contribution to the

  10. Reinvestigation of the Cd–Gd phase diagram

    PubMed Central

    Reichmann, Thomas L.; Ipser, Herbert

    2014-01-01

    The complete Cd–Gd equilibrium phase diagram was investigated by a combination of powder-XRD, SEM and DTA. All previously reported phases, i.e., CdGd, Cd2Gd, Cd3Gd, Cd45Gd11, Cd58Gd13, and Cd6Gd, could be confirmed. In addition, a new intermetallic compound with a stoichiometric composition corresponding to “Cd8Gd” was found to exist. It was obtained that “Cd8Gd” decomposes peritectically at 465 °C. Homogeneity ranges of all intermetallic compounds were determined at distinct temperatures. In addition, the maximum solubilities of Cd in the low- and high-temperature modifications of Gd were determined precisely as 4.6 and 22.6 at.%, respectively. All invariant reaction temperatures (with the exception of the formation of Cd58Gd13) as well as liquidus temperatures were determined, most probably, Cd58Gd13 is formed in a peritectoid reaction from Cd45Gd11 and Cd6Gd at a temperature below 700 °C. PMID:25544803

  11. Large Relative Cooling Power in Dy5Si4:Dy5Si3 composite

    NASA Astrophysics Data System (ADS)

    Samatham, S. Shanmukharao; Venkateshwarlu, D.; Pandya, Swati; Gangrade, Mohan; Chandra, L. S. Sharath; Jain, Deepti; Ganesan, V.

    2011-07-01

    Anomalously large RCP (Relative Cooling Power) and a reasonable high adiabatic change `?T' has been observed in magnetocaloric composite sample Dy5Si4 : Dy5Si3 for a nominal ratio of 2:1. Observed magnetic ordering temperatures for such a composite is 136 K and 39 K respectively which can be assigned to its constituents. Even though the observed `?T' is only 5 K for a field of 14 T, the combined RCP is very large, viz 1283 J/kg. Added merit is the width of temperature over which cooling can be done is 95 K. This makes the system more promising and may be a possible candidate for the Ericsson cycle over a temperature range from 140-35 K.

  12. Adjunct Immunotherapy of Tuberculosis in Drug-Resistant TB and TB\\/HIV Co-Infected Patients

    Microsoft Academic Search

    Nathalia D. Prihoda; Olga V. Arjanova; Lyudmila V. Yurchenko; Nina I. Sokolenko; Lyudmila A. Vihrova; Volodymyr S. Pylypchuk; Galyna A. Kutsyna

    Open-label, salvage anti-tuberculosis therapy (ATT) combined with DZHERELO (IMMUNOXEL), SVITANOK, and LIZORM - over- the-counter immunomodulators from medicinal plants - was conducted in 20 Ukrainian patients, comprising seven who had HIV co- infection. Except five patients with HIV, all other individuals had multidrug-resistant TB (MDR-TB) including 7 (35%) patients with XDR-TB. Patients hospitalized in our TB dispensary were treated under

  13. Characteristics and TB treatment outcomes in TB patients with viral hepatitis, New York City, 2000-2010.

    PubMed

    Bushnell, G; Stennis, N L; Drobnik, A M; Proops, D C; Ahuja, S D; Bornschlegel, K; Fuld, J

    2015-07-01

    Literature surrounding the burden of and factors associated with hepatitis B virus (HBV) and hepatitis C virus (HCV) infection in persons with tuberculosis (TB) disease remains limited and focused on populations outside the USA. Cross-matched New York City (NYC) TB and viral hepatitis surveillance data were used to estimate the proportion of NYC adults diagnosed with TB from 2000 to 2010 with a report of viral hepatitis infection and to describe the impact of viral hepatitis infection on TB treatment completion and death. For 9512 TB patients, HCV infection was reported in 4·2% and HBV infection in 3·7%; <1% of TB patients had both HCV and HBV infection. The proportion of TB patients with HCV infection to die before TB treatment completion was larger than in TB patients without a viral hepatitis report (21% vs. 9%); this association remained when stratified by HIV status. There was no significant difference in death before treatment completion for TB patients with HBV infection compared to TB patients without a viral hepatitis report when stratified by HIV status. These findings reinforce the importance of hepatitis testing and providing additional support to TB patients with viral hepatitis infection. PMID:25387450

  14. An evaluation of UV protection imparted by cotton fabrics dyed with natural colorants

    Microsoft Academic Search

    Ajoy K Sarkar

    2004-01-01

    BACKGROUND: The ultraviolet properties of textiles dyed with synthetic dyes have been widely reported in literature. However, no study has investigated the ultraviolet properties of natural fabrics dyed with natural colorants. This study reports the Ultraviolet Protection Factor (UPF) of cotton fabrics dyed with colorants of plant and insect origins. METHODS: Three cotton fabrics were dyed with three natural colorants.

  15. Magnetic ordering in GdAuCd

    NASA Astrophysics Data System (ADS)

    ??tka, Kazimierz; Kmie?, Roman; Pacyna, Andrzej W.; Fickenscher, Thomas; Hoffmann, Rolf-Dieter; Pöttgen, Rainer

    2004-09-01

    A polycrystalline sample of GdAuCd was prepared by reaction of the elements in a sealed tantalum ampoule in an induction furnace. The structure was studied by X-ray powder and single-crystal diffraction: ZrNiAl type, P 6¯2m , a=770.1(2), c=396.0(1) pm, wR2=0.0493 for 252 F2 values and 14 variables. The structure contains two crystallographically different gold sites with tricapped trigonal prismatic coordination: [Au1Cd 3Gd 6] and [Au2Cd 6Gd 3]. Together the gold and cadmium atoms form a three-dimensional [AuCd] network in which the gadolinium atoms fill distorted hexagonal channels. The magnetic and electronic properties have been studied by means of AC and DC magnetic susceptibility measurements as well as 155Gd Mössbauer spectroscopy on powder samples. It was found that GdAuCd orders antiferromagnetically at TN=66.5 K.

  16. A study of electrode temperature lowering in Dy-containing ceramic metal halide lamps: I. The effect of mixtures of Dy, Tl and Na compared with pure Dy

    NASA Astrophysics Data System (ADS)

    Westermeier, M.; Ruhrmann, C.; Bergner, A.; Denissen, C.; Suijker, J.; Awakowicz, P.; Mentel, J.

    2013-05-01

    The reduction in the electrode temperature by the gas phase emitter effect of dysprosium in ceramic metal halide lamps is investigated within special research lamps in dependence on the operating frequency of switched-dc lamp currents. The lamp tubes are made of transparent YAG material. They are filled with a fixed amount of Hg, which produces a buffer gas during lamp operation at a pressure of 2 MPa, with different amounts of DyI3 and in part with different amounts of NaI plus TlI. The Dy atomic ground state density is measured phase resolved both in the middle of the discharge and in front of the upper electrode by broad band absorption spectroscopy. The Dy ion density in front of the electrode is evaluated from line intensities being measured in absolute units by emission spectroscopy. The electrode tip temperature is determined by a 1? - 2D pyrometric measuring method. It is found that a high Dy ion density in front of the electrode is correlated with a strong reduction in the electrode tip temperature relating to a pure mercury lamp. At low operating frequencies (f ? 100 Hz) the Dy ion density and the temperature reduction is high within the cathodic phase and low within the anodic phase, at higher operating frequencies an increased Dy ion density and a reduction in the electrode tip temperature overlaps onto the anodic phase. The Dy ion density is reduced and with it the tip temperature drop by an addition of Na and Tl vapour to the lamp plasma. The effect of Tl and Na is investigated in more detail in a successive paper.

  17. Two novel Dy8 and Dy11 clusters with cubane [Dy4(?3-OH)4]8+ units exhibiting slow magnetic relaxation behaviour.

    PubMed

    Miao, Yan-Li; Liu, Jun-Liang; Li, Jin-Yan; Leng, Ji-Dong; Ou, Yong-Cong; Tong, Ming-Liang

    2011-10-21

    Two unique octa- and hendeca-nuclear dysprosium(III) clusters incorporating [Dy(4)(?(3)-OH)(4)](8+) cubane units have been synthesized with the 1,10-phenanthroline-2,9-dicarbaldehyde dioxime (H(2)phendox) ligand and DyCl(3)·6H(2)O or Dy(OAc)(3)·4H(2)O. They are [Dy(8)(OH)(8)(phendox)(6)(H(2)O)(8)]Cl(2)(OH)(2)·18H(2)O·18MeOH (1) and [Dy(11)(OH)(11)(phendox)(6)(phenda)(3)(OAc)(3)](OH)·40H(2)O·7MeOH (2). Adjacent Dy(8) in 1 or Dy(11) in 2 motifs are packed by off-set ?-? interactions of the aromatic rings on phendox(2-) to generate a 3D supramolecular architecture in the honeycomb topology and with 1D or 3D channels along the c-axis. Adsorption research shows that complex 1 has selective adsorption ability for H(2)O over small gas molecules (H(2), N(2), CO(2)). Complex 2 is stable upon the removal of guest molecules and the desolvated compound absorbed a considerable amount of CO(2). Furthermore, the oximes underwent hydrolysis to carboxylic acid and the resulting 1,10-phenanthroline-2,9-dicarboxylate link the dysprosium atoms to form a hendecanuclear cluster of 2. Magnetic studies reveal that both clusters exhibit slow magnetic relaxation behavior, expanding upon the recent reports of the pure 4f type single-molecule magnets (SMMs). PMID:21894344

  18. Extended family of new Bi-2222 superconducting cuprates Bi 2Sr 2(RE 1- xCe x) 2Cu 2O 10+ y, RE=rare earth

    NASA Astrophysics Data System (ADS)

    Arima, T.; Tokura, Y.; Takagi, H.; Uchida, S.; Beyers, R.; Torrance, J. B.

    1990-06-01

    We report the synthesis of a new class of layered cuprates with BiO bilayers: Bi 2Sr 2(RE 1- xCe x) 2Cu 2O 10+ y (Bi-2222 phase) with RE=Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er and Tm (at x=0.18). Superconductivity is observed for RE=Y, Nd, Sm, Eu, Gd, Dy and Ho, but not for Pr, Tb, Er and Tm. The transition temperature ( Tc) is highest for the Gd derivative (34K) and progressively decreases for larger or smaller RE ions. The origin of this effect is discussed.

  19. Innovative clinical trial designs to rationalize TB vaccine development.

    PubMed

    Ellis, R D; Hatherill, M; Tait, D; Snowden, M; Churchyard, G; Hanekom, W; Evans, T; Ginsberg, A M

    2015-05-01

    A recent trial of a leading tuberculosis (TB) vaccine candidate in 3000 South African infants failed to show protection over that from BCG alone, and highlights the difficulties in clinical development of TB vaccines. Progression of vaccine candidates to efficacy trials against TB disease rests on demonstration of safety and immunogenicity in target populations and protection against challenge in preclinical models, but immunologic correlates of protection are unknown, and animal models may not be predictive of results in humans. Even in populations most heavily affected by TB the sample sizes required for Phase 2b efficacy trials using TB disease as an endpoint are in the thousands. Novel clinical trial models have been developed to evaluate candidate TB vaccines in selected populations using biologically relevant outcomes and innovative statistical approaches. Such proof of concept studies can be used to more rationally select vaccine candidates for advancement to large scale trials against TB disease. PMID:25802031

  20. Growth and luminescent properties of Lu 2SiO 5:Ce and (Lu 1- xGd x) 2SiO 5:Ce single crystalline films

    NASA Astrophysics Data System (ADS)

    Zorenko, Yu.; Gorbenko, V.; Savchyn, V.; Voznyak, T.; Grinyov, B.; Sidletskiy, O.; Kurtsev, D.; Fedorov, A.; Baumer, V.; Nikl, M.; Mares, J. A.; Beitlerova, A.; Prusa, P.; Kucera, M.

    2011-12-01

    Single crystalline films (SCF) of Lu 2SiO 5:Ce (LSO:Ce), (Lu 1- xGd x) 2SiO 5:Ce (LGSO:Ce) and LGSO:Ce,Tb orthosilicates with thickness of 2.5-21 ?m were crystallized by liquid phase epitaxy method onto undoped LSO substrates from melt-solution based on PbO-B 2O 3 flux. The concentration of Gd was varied in the range of x=0.2-0.7 formula units (f.u.). In the case of LGSO:Ce SCF growth we do not use any additional doping for reducing the misfit between the SCF and substrate lattices. The luminescence and scintillation properties of LSO:Ce, LGSO:Ce and LGSO:Ce,Tb SCFs were mutually compared and confronted with the performance of reference LSO:Ce and LYSO:Ce crystals. With increasing Gd content the luminescence spectrum of LGSO:Ce SCF is gradually red-shifted with respect to that of LSO:Ce SCF. The LY of (Lu 1- xGd x)SO:Ce SCF becomes lower in comparison with that for LSO:Ce SC at increasing Gd content in the range of x=0.2-0.7 f.u. The peculiarities of luminescence properties of LSO:Ce and LGSO:Ce SCFs in comparison with crystal analogs are explained by the different distribution of Ce 3+ over Lu1 and Lu2 positions of LSO host and by the influence of Pb 2+ contamination coming from the flux used for the film growth.

  1. Local Structure of Multiferroic TbMn2O5: Evidence for an Anomalous Tb-O Distribution

    SciTech Connect

    Tyson,T.; Deleon, M.; Yoong, S.; Cheong, S.

    2007-01-01

    The temperature dependent local structure of TbMn2O5 was determined by x-ray-absorption spectroscopy. An anomalous Tb-O distribution is found. At high temperature, it is broad but resolves into two distinct peaks below 180 K. The distributions sharpen below the Tb magnetic ordering temperature 10 K. The distortions in the Tb-O distribution, away from the Pbam structure, are consistent with rotations of the MnOx polyhedra about the c axis and suggest that Tb-O bond polarization may play a significant role in the observed ferroelectric properties of this system.

  2. Giant low-field magnetostriction of epoxy/TbxDy1-x(Fe0.8Co0.2)2 composites (0.20 ? x ? 0.40)

    NASA Astrophysics Data System (ADS)

    Liu, J. J.; Pan, Z. B.; Si, P. Z.; Du, J.

    2013-07-01

    Spin configuration, magnetocrystalline anisotropy compensation, and magnetostriction of TbxDy1-x(Fe0.8Co0.2)2 (0.20 ? x ? 0.40) compounds have been investigated. Experimental evidence for the anisotropy compensation has been observed directly by performing x-ray diffraction on magnetic-field aligned powders and by evaluating the Mössbauer spectra. The easy magnetization direction (EMD) at room temperature rotates from the ?100? (x ? 0.27) to the ?111? axis (x ? 0.32), subjected to the anisotropy compensation between Tb3+ and Dy3+ ions. The strong grain-?111?-oriented pseudo-1-3 epoxy/composite has been fabricated by curing under a moderate magnetic field. A giant low-field magnetostriction, longitudinal ?|| and linear anisotropic ?a (=?|| - ??) up to 550 and 760 ppm at 3 kOe, respectively, is obtained for Tb0.32Dy0.68(Fe0.8Co0.2)2 composite, which can be attributed to anisotropy compensation, a large magnetostriction coefficients ?111, EMD lying along ?111? direction, the strong ?111?-textured orientation, and the chain structure. The good magnetoelastic properties, besides only containing 27 vol. % alloy particles in the insulating epoxy, make it a promising candidate for magnetostriction applications.

  3. Light emission efficiency and imaging performance of Gd{sub 2}O{sub 2}S:Eu powder scintillator under x-ray radiography conditions

    SciTech Connect

    Michail, C. M.; Fountos, G. P.; Liaparinos, P. F.; Kalyvas, N. E.; Valais, I.; Kandarakis, I. S.; Panayiotakis, G. S. [Department of Medical Physics, Faculty of Medicine, University of Patras, 265 00 Patras (Greece); Department of Medical Instruments Technology, Technological Educational Institute, 122 10 Athens (Greece); Department of Medical Physics, Faculty of Medicine, University of Patras, 265 00 Patras (Greece)

    2010-07-15

    Purpose: To evaluate Gd{sub 2}O{sub 2}S:Eu powder phosphor as a radiographic image receptor and to compare it to phosphors often used in radiography. Gd{sub 2}O{sub 2}S:Eu is nonhygroscopic, emitting red light with decay time close to that of Gd{sub 2}O{sub 2}S:Tb. Methods: The light intensity emitted per unit of x-ray exposure rate (absolute luminescence efficiency) was measured for laboratory prepared screens with coating thicknesses of 33.1, 46.4, 63.1, 78.3, and 139.8 mg/cm{sup 2} and tube voltages ranging from 50 to 140 kVp. Parameters related to image quality such as the modulation transfer function (MTF) and the detective quantum efficiency (DQE) were also experimentally examined. In addition, a previously validated Monte Carlo code was used to estimate intrinsic x-ray absorption and optical properties, as well as the MTF and the Swank factor (I) of the Gd{sub 2}O{sub 2}S:Eu scintillators. Results: Gd{sub 2}O{sub 2}S:Eu light intensity was found higher than that of single CsI:Tl crystal for tube voltages up to 100 kVp. The MTF and the DQE were found to be comparable with those of Gd{sub 2}O{sub 2}S:Tb and CsI:Tl screens. MTF estimated by the Monte Carlo code was found very close to the experimental MTF values. Gd{sub 2}O{sub 2}S:Eu showed peak emission in the wavelength range 620-630 nm. Its emission spectrum was excellently matched to various optical detectors (photodiodes, photocathodes, CCDs, and CMOS) employed in flat panel detectors. Conclusions: Gd{sub 2}O{sub 2}S:Eu is an efficient phosphor potentially well suited to radiography and especially to some digital detectors sensitive to red light.

  4. (Tb_1-xY_x)Ni_2Ge_2: From Ising Antiferromagnet to Ising Spin Glass.

    NASA Astrophysics Data System (ADS)

    Canfield, P. C.; Wiener, T.; Bud'Ko, S. L.

    2000-03-01

    Recent measurements [1,2] on single crystals of RNi_2Ge2 compounds have revealed complex, anisotropies and H-T phase diagrams. In addition recent work on (Gd_1-xEu_x)Ni_2Ge2 has demonstrated our ability to change the band filling so as to tune the ordering wave-vector of the magnetically ordered state [3]. In this talk we will present the results of measurements on another pseudo- ternary series: (Tb_1-xY_x)Ni_2Ge_2. The Tb local moments are aligned along the crystallographic c-axis for all concentrations of Y and as Y replaces Tb the two magnetic transition temperatures decrease rapidly. For x > 0.6 the low temperature ground state of the magnetic sublattice is that of an Ising spin glass. T -x phase diagrams and detailed characterization of the spin glass state will be presented. [1]S.L.Bud'ko et al. JMMM 205, 53 (1999). [2]Z.Islam et al. PRB 58, 8522 (1998). [3]Z.Islam et al. PRL 83, 2817 (1999). Ames Laboratory is operated for the US Department of Energy by Iowa State University under Contract No. W-7405-Eng-82. This work was supported by the Director for Energy Research, Office of Basic Energy Sciences.

  5. Magnetic excitations in the spin-spiral state of TbMnO3 and DyMnO3

    NASA Astrophysics Data System (ADS)

    Milstein, Alexander I.; Sushkov, Oleg P.

    2015-03-01

    We calculate spectra of magnetic excitations in the spin-spiral state of perovskite manganates. The spectra consist of several branches corresponding to different polarizations and different ways of diffraction from the static magnetic order. The easy-axis crystal-field anisotropy and the Dzyaloshinski-Moriya anisotropy lead to opening of gaps in Goldstone modes and to discontinuities in magnon dispersions. Comparing results of the calculation with available experimental data, we determine values of effective exchange parameters and anisotropies. To simplify calculations and to get a clearer physical insight into the structure of excitations, we use the ? -model-like effective-field theory instead of the conventional spin-wave approach to analyze the Heisenberg Hamiltonian and to derive the spectra.

  6. Optical properties of Dy3+ doped yttrium aluminium borate

    Microsoft Academic Search

    R. Martínez Vázquez; R. Osellame; M. Marangoni; R. Ramponi; E. Diéguez; M. Ferrari; M. Mattarelli

    2004-01-01

    A Dy3+ doped yttrium-aluminium borate (Dy:YAB) crystal has been optically characterized. The refractive indices at seven different wavelengths, ranging from the visible to the near infrared (IR), have been measured and the Sellmeier curves have been calculated. The polarized optical absorption spectra have been obtained at room temperature, and the Judd-Ofelt parameters have been calculated. The lifetime of the upper

  7. Photoacoustic Spectra of Sm3 , Eu3 , Dy3 Complexes

    Microsoft Academic Search

    Zhang Yugeng

    1993-01-01

    The complexes crystals of Sm(Ac)3.4H2O, Eu(Ac)3.4H2O and a new complex Dy2(Ac)(NO3)4.12H2O were synthesized and their PA spectra were determined firstly. All their PA spectra absorptions are interpreted. The fluorescence properties of Sm, Eu, Dy and the relaxation process models were studied by their PA spectra.

  8. Magnetic order in DyFe 2Si 2 compound

    NASA Astrophysics Data System (ADS)

    Bourée-Vigneron, F.; Pinot, M.; Go??b; , M.; Szytu?a, A.; Ole?, A.

    1990-05-01

    Neutron diffraction measurements performed on polycrystalline DyFe 2Si 2 sample (body-centered tetragonal ThCr 2Si 2 type crystal structure) indicate that the compound becomes antiferromagnetic below the Néel temperature (3.8 K). The magnetic moment alignment of Dy 3+ ions is described as a modulated structures with a wave vector k = (0.335, 0, 0.136) with ? = 7.52(5)? B at T = 1.3 K.

  9. Boundary states of D-branes and dy-strings

    Microsoft Academic Search

    Li Miao

    1996-01-01

    Polchinski's recent construction of Dirichlet branes of R-R charges, together with Witten's mechanism for forming bound states of both NS-NS charges and R-R charges, provides a rigorous method to treat these dy-branes. We construct the massless sector of boundary states of D-branes, as well as of dy-strings of charge (p, 1). As a consequence, the string tension formula predicted by

  10. Analysis neutral data structure for GD&T

    Microsoft Academic Search

    Zhengshu Shen; Jami J. Shah; Joseph K. Davidson

    2008-01-01

    The fundamental issue for automatic geometric tolerance analysis is the representation model, which should, in conjunction\\u000a with CAD models, accurately and completely represent the GD&T specification according to the GD&T standards. Furthermore,\\u000a such a representation model should facilitate GD&T validation and tolerance analysis. Most GD&T representation models proposed\\u000a so far are specific to the tolerance analysis method. Common tolerance analysis

  11. Slow magnetic relaxation in a novel heptanuclear Dy 7 cluster with five edge-sharing Dy 3 triangles

    Microsoft Academic Search

    Fu-Sheng Guo; Peng-Hu Guo; Zhao-Sha Meng; Ming-Liang Tong

    A unique Dy7 cluster with five edge-sharing Dy3 triangles has been synthesized by incorporating the polydentate oxime ligand, 3-methyloxysalicylaldoxime, in two different binding modes in its mono- and di-deprotonated state. Both static (dc) and dynamic (ac) magnetic properties of 1 have been studied, possible single-molecule magnet behavior is observed, expanding upon the recent reports of the pure 4f type SMM.

  12. 149Gd: What's Confirmed? What's New?

    NASA Astrophysics Data System (ADS)

    Kintz, N.; Finck, Ch.; Stezowski, O.; Vivien, J. P.; Nourreddine, A.; Zuber, K.; Appelbe, D. E.; Beausang, C. W.; Beck, F. A.; Byrski, T.; Courtin, S.; Curien, D.; Duchene, G.; Ertuerk, S.; de France, G.; Gall, B. J. P.; Haas, B.; Khadiri, N.; Lopez-Martens, A.; Pachoud, E.; Rigollet, C.; Smith, M.; Twin, P. J.

    1999-03-01

    A long run performed with EUROGAM II allowed remeasuring the 149Gd superdeformed (SD) band 1. The ? I = 4 bifurcation in band 1 is confirmed and two resolved ? -ray transitions linking the SD band 1 and the normal deformed states have been observed.

  13. Phonon coupling to the Tb spin in multiferroic TbMn2O5

    NASA Astrophysics Data System (ADS)

    Yoon, Young-Noh; Sushkov, A. B.; Valdes Aguilar, R.; Drew, H. D.; Hur, N.; Cheong, S. W.

    2006-03-01

    TbMn2O5 is a representative of a group of multiferroic materials where ferroelectricity is induced by spiral magnetic ordering at low temperatures. These materials demonstrate several weak structural and magnetic transitions reflecting complex interplay between magnetic order and the lattice. Phonons serve as a probe of lattice changes and, via spin- phonon coupling, of magnetic ordering. We measured the reflectivity spectra in a- and b-polarizations of an orthorhombic single crystal. The Tb-dominating phonons are active in both polarizations but only b-polarization shows a magnetic shift below 24 K where Tb moments start to order. We made lattice dynamics calculations using popular GULP program to understand why a particular infrared phonon is strongly coupled to spin ordering.

  14. Electron-yield EXAFS studies of Tb/FeCo and Tb/Fe multilayers

    SciTech Connect

    Choi, Myung Hi (Catholic Univ. Medical Coll., Seoul (Republic of Korea). Dept. of Physics); Joo, Jung Hoon (Korea Inst. of Science and Technology, Seoul (Republic of Korea). Materials Design Lab.); Lee, Jung Geun; Yang, Chang Sun (SKC Ltd., Chonan (Republic of Korea). Central Research Center); Kim, Kimoon; Whang, Dongmok (Pohang Inst. of Science and Technology (Republic of Korea). Dept. of Chemistr

    1991-01-01

    By using the electron-yield detection technique, the EXAFS spectra for Tb/FeCo and Tb/Fe multilayers, as well as a TbFeCo alloy and some reference thin films, have been measured. These multilayers were prepared by sputtering onto float-glass substrates, and had the total thickness of 1000{Angstrom} with various individual layer thickness or period values. An electron detector obtained from the EXAFS company of F.W. Lytle was used for the measurements and the high quality of data shows that the electron-yield detection technique is especially suitable for studies of multilayers. Preliminary analysis results show some qualitative tendencies which need to be checked with more careful analyses and, if possible, with some low temperature data. 9 refs., 3 figs.

  15. pH-induced Dy? and Dy?? cluster-based 1D chains with different magnetic relaxation features.

    PubMed

    Wu, Zhi-Lei; Dong, Jie; Ni, Wei-Yan; Zhang, Bo-Wen; Cui, Jian-Zhong; Zhao, Bin

    2014-11-28

    Two novel tetra- and deca-nuclear dysprosium compounds, namely, [Dy4(?3-OH)2(L)10(bipy)2(H2O)2]n (1) and {[Dy10(?3-OH)8(L)22(bipy)2(H2O)2]·5H2O}n (2) (L = 3-fluoro-4-(trifluoromethyl)benzoic acid; bipy = 2,2'-bipyridine), have been successfully obtained by hydrothermal reaction at different pH values. The solid state structures of 1 and 2 were established by the single crystal X-ray diffraction technique, and both of them exhibit complicated 1D chains with [Dy4] (1) and [Dy10] (2) cluster units, respectively. Adjacent [Dy4] in 1 and [Dy10] in 2 are connected by two bridging carboxylate groups in the ?(1):?(1):?2 mode. Magnetic studies reveal that they exhibit different magnetic relaxation behaviors with the energy barrier of 23.6 K for 1 and 3.2 K for 2. Interestingly, the large divergence in both the structures and magnetic properties for 1 and 2 only originated from the different pH values in preparing them. PMID:25293936

  16. Couples Magnetic and Structural Transitions in High-Purity Dy and Gd5SbxGe4-x

    Microsoft Academic Search

    Alexander S. Chernyshov

    2006-01-01

    Magnetic materials exhibiting magnetic phase transitions simultaneously with structural rearrangements of their crystal lattices hold a promise for numerous applications including magnetic refrigeration, magnetomechanical devices and sensors. We undertook a detailed study of a single crystal of dysprosium metal, which is a classical example of a system where magnetic and crystallographic sublattices can be either coupled or decoupled from one

  17. Investigation of nanostructured Lu2O3:Tb

    NASA Astrophysics Data System (ADS)

    Zych, E.; Deren, Przemyslaw J.; Strek, Wieslaw; Meijerink, Andries; Domagala, K.; Mielcarek, W.

    2001-04-01

    Nano structured Lu2O3, both plane and doped with Tb, was prepared utilizing a combustion technique. The best crystallity of the products can be obtained initiating the reaction within 560-700 $DEGC range of temperature. Tb easily enters the nano scaled host lattice both as Tb3+ and Tb4+. The former gives rise to a typical green emission of the ion, while the later introduces a broad-band visible absorption, due to charge transfer transitions. The green emission of Tb3+ from a raw material may be radically increased by after- preparation heat-treatment. Undoped material gives rise to a blue emission, which disappears when Tb content with respect to Lu reaches 0.0001% or higher level.

  18. Rare-earth chromium gallides RE{sub 4}CrGa{sub 12} (RE=Tb-Tm)

    SciTech Connect

    Slater, Brianna R.; Bie, Haiying; Stoyko, Stanislav S. [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada)] [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada); Bauer, Eric D.; Thompson, Joe D. [Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)] [Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Mar, Arthur, E-mail: arthur.mar@ualberta.ca [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada)] [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada)

    2012-12-15

    The ternary rare-earth-metal chromium gallides RE{sub 4}CrGa{sub 12} (RE=Tb-Tm) have been prepared by reactions of the elements at 1000 Degree-Sign C in the presence of excess gallium used as a self-flux. Their structures are derived by inserting Cr atoms into a quarter of the empty Ga{sub 6} octahedral clusters found in the parent binary gallides REGa{sub 3} (AuCu{sub 3}-type), although single-crystal X-ray diffraction studies suggest that complex superstructures may be adopted. An ideal ordered Y{sub 4}PdGa{sub 12}-type structure was successfully refined for a crystal of Dy{sub 4}CrGa{sub 12} (Pearson symbol cI34, space group Im3{sup Macron }m, Z=2, a=8.572(1) A). Magnetic measurements on single-crystal samples reveal ferromagnetic or possibly ferrimagnetic ordering for the Tb, Dy, and Er members (T{sub C}=22, 15, and 2.8 K, respectively) and antiferromagnetic ordering for the Ho member (T{sub N}=7.5 K). Band structure calculations on a hypothetical 'Y{sub 4}CrGa{sub 12}' model suggest that the Cr atoms carry no local magnetic moment. - Graphical abstract: RE{sub 4}CrGa{sub 12} is derived by inserting Cr atoms into empty Ga{sub 6} octahedral clusters present in the parent binary gallides REGa{sub 3}. Highlights: Black-Right-Pointing-Pointer RE{sub 4}MGa{sub 12} (previously known for M=Fe, Ni, Pd, Pt, Ag) has been extended to M=Cr. Black-Right-Pointing-Pointer RE{sub 4}CrGa{sub 12} compounds show predominantly ferromagnetic ordering. Black-Right-Pointing-Pointer Band structure calculations suggest that Cr atoms carry no local magnetic moment.

  19. Large magnetic entropy changes in Gd-Co amorphous ribbons

    NASA Astrophysics Data System (ADS)

    Zhang, C. L.; Wang, D. H.; Han, Z. D.; Xuan, H. C.; Gu, B. X.; Du, Y. W.

    2009-01-01

    A series of magnetic amorphous ribbons with different Gd/Co ratios was prepared by melt-spun method. With the decrease in Gd/Co ratio, Curie temperatures increase gradually from 166 to 193 K. The maximum values of magnetic entropy changes under a magnetic field of 10 kOe are -3.1, -3.0, -2.9, and -2.8 J/kg K for Gd71Co29, Gd68Co32, Gd65Co35, and Gd62Co38 samples, respectively. The approximately constant peak values of ?SM at different working temperatures indicate that they are advantageous for an Ericsson refrigeration cycle. In addition, these samples have large resistivity and greatly reduced magnetic hysteresis losses, which could increase the refrigeration efficiency. These advantages make the Gd-Co amorphous ribbons good candidates for the practical magnetic refrigeration.

  20. Crystal Structure of TbNiD 3.3

    Microsoft Academic Search

    Yu. L. Yaropolov; S. S. Agafonov; V. P. Glazkov; V. A. Somenkov; V. N. Verbetsky

    2011-01-01

    A TbNi-based deuteride has been prepared by hydriding TbNi at a temperature of 297 K and a deuterium pressure no higher than\\u000a 0.25 MPa. The structure of TbNiD3.3 differs from that of the parent intermetallic compound, indicating that deuteration causes structural changes in the metallic\\u000a sublattice. The deuteride has an orthorhombic structure (CrB type, sp. gr. Cmcm) in which the

  1. Magnetostriction of growth textured Tb-Zn alloys

    NASA Astrophysics Data System (ADS)

    Delaney, D. W.; Lograsso, T. A.

    1999-11-01

    The magnetostrictive performance of aligned microstructural composites of Tb-Zn alloys were experimentally tested at 77 K under compressive loads ranging from approximately 0-50 MPa and applied magnetic field up to 2000 Oe. Tb-8a/oZn, Tb-42a/oZn and the eutectic composition of Tb-27.8a/oZn were all directionally solidified to prepare aligned, textured microstructures. The eutectic sample grew with lamellar plates with the magnetically hard axes for each phase parallel with the rod axis and exhibited a strain of less than 100 ppm. The Tb-42a/oZn alloy solidified with TbZn dendrites in the magnetically hard [1 1 1] direction and exhibited a strain of 375 ppm. The Tb-8a/oZn alloy solidified pure Tb dendrites in the magnetically easy direction, the b-axis, yet it only displayed a 350-ppm magnetostriction at a maximum field of 2000 Oe due to the high anisotropy of the Tb dendrites.

  2. First Outcome of MDR-TB among Co-Infected HIV/TB Patients from South-West Iran

    PubMed Central

    Motamedifar, Mohammad; Abadi, Ali Reza Hassan; Moghadam, Mahboube Nakhzari

    2015-01-01

    Background Tuberculosis (TB) is the leading cause of mortality among human immunodeficiency virus (HIV) patients and the majority of them occur in developing countries. The aims of the present study were to determine the frequency of HIV/TB co-infection and other probable associated factors. Methods This 10 year retrospective study was conducted on 824 HIV patients in the south-west of Iran. HIV infection was diagnosed by the enzyme linked immunosorbent assay and confirmed by Western blot. TB diagnosis was based on consistency of the clinical manifestations, chest X-ray, and microscopic examination. Drug susceptibility testing was done by the proportional method on Löwenstein-Jensen media. Results Of 824 HIV patients, 59 (7.2%) were identified as TB co-infected and the majority (86.4%) of them were male. Of the overall TB infected patients, 6 cases (10.2%) showed multidrug-resistant with the mean CD4+ lymphocyte count of 163±166 cells/mm3. The main clinical forms of TB were pulmonary (73%). There was a significant (p<0.05) correlation between TB infection and CD4+ lymphocyte counts ?200 cells/mm3, gender, prison history, addiction history, and highly active anti-retroviral therapy. Conclusion We reported novel information on frequency of HIV/TB co-infection and multidrug resistant-TB outcome among co-infected patients that could facilitate better management of such infections on a global scale.

  3. Magnetism and 155Gd Mössbauer spectroscopy of GdAuMg

    NASA Astrophysics Data System (ADS)

    ??tka, Kazimierz; Kmie?, Roman; Pacyna, Andrzej W.; Fickenscher, Thomas; Hoffmann, Rolf-Dieter; Pöttgen, Rainer

    2004-03-01

    GdAuMg was synthesized by reaction of the elements in a sealed tantalum ampule in a high-frequency furnace. The structure was investigated by X-ray diffraction on both powders and single crystals: ZrNiAl type, P 6¯2m , a=756.3(1), c=412.71(7) pm, wR2=0.0285 for 308 F2 values, 14 variables. Geometrical motifs of the GdAuMg structure are gold centered tricapped trigonal prisms [Au1Mg 3Gd 6] and [Au2Mg 6Gd 3]. Together the gold and magnesium atoms form a three-dimensional [AuMg] network in which the gadolinium atoms fill distorted hexagonal channels. Bulk magnetic properties have been investigated by means of AC and DC magnetic susceptibility measurements and 155Gd Mössbauer spectroscopy was used to monitor the local electronic and magnetic structure. Two magnetic phase transitions were found. One transition, at T1= TN=81.1(1) K, is from a paramagnetic to an antiferromagnetic state of collinear character and the other at T2=19.0(1) from the antiferromagnetic to a kind of canted magnetic ordering characterized by a very narrow hysteresis loop.

  4. Magnetic structure of Gd, GdH2 and NdH2 single crystal films

    NASA Astrophysics Data System (ADS)

    Hémon, S.; Cowley, R. A.; Ward, R. C. C.; Wells, M. R.; Douysset, L.; Ronnow, H.

    2000-06-01

    Single crystal films of Gd and Nd were grown by MBE techniques using the LaMBE facility in Oxford. The thickness of the layers was 5000 Å and the mosaic spread about 0.2-0.3°. Some of the layers were hydrogenated by KTH in Stockholm to obtain the dihydride. The magnetic structures were determined using the TAS1 triple axis spectrometer at the Risø National Laboratory in Denmark. The magnetic structure of the Gd film was a ferromagnet, similar to that of bulk Gd. In detail, however, there were differences and the spin direction differed from that of the bulk material while the phase with the moments aligned along the c-axis was absent in the film. The magnetic structure of GdH2 was antiferromagnetic with a wavevector of (½½½) and a transition temperature of 22+/-0.5 K, much lower than that of bulk Gd, 290 K. In contrast, the magnetic structure of NdH2 is incommensurate with a wavevector of (0.532 0.532 1.532) and a magnetic ordering temperature of 34+/-1 K.

  5. Thermochemical investigations in the system Cd-Gd.

    PubMed

    Reichmann, Thomas L; Ganesan, Rajesh; Ipser, Herbert

    2014-10-15

    Vapour pressure measurements were performed in terms of a non-isothermal isopiestic method to determine vapour pressures of Cd in the system Cd-Gd between 693 and 1045 K. From these results thermodynamic activities of Cd were derived as a function of temperature for the composition range 52-86 at.% Cd. By employing an adapted Gibbs-Helmholtz equation, partial molar enthalpies of mixing of Cd were obtained for the corresponding composition range, which were used to convert the activity values of Cd to a common average sample temperature of 773 K. The relatively large variation of the activity across the homogeneity ranges of the phases Cd2Gd and Cd45Gd11 indicates that they probably belong to the most stable intermetallic compounds in this system. An activity value of Gd for the two phase field Cd6Gd+L was available from literature and served as an integration constant for a Gibbs-Duhem integration. Integral Gibbs energies are presented between 51 and 100 at.% Cd at 773 K, referred to Cd(l) and ?-Gd(s) as standard states. Gibbs energies of formation for the exact stoichiometric compositions of the phases Cd58Gd13, Cd45Gd11, Cd3Gd and Cd2Gd were obtained at 773 K as about -19.9, -21.1, -24.8, and -30.0 kJ g atom-(1), respectively. PMID:25328283

  6. Two distinct Dy-isophthalates induced by different solvents

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Huang, Yuan-Yuan; Yao, Yuan-Gen

    2012-09-01

    Two distinct Dy-isophthalates, [Dy4(m-BDC)6(H2O)4(DMF)]n?2n(H2O)?n(DMF) 1 and [Dy2(m-BDC)3(H2O)(DMA)]n?3n(H2O)?2n(DMA) 2 (DMF = N,N'-Dimethylformamide, DMA = N,N'-Dimethylacetamide), which were induced by different solvents under the same hydrothermal conditions, were obtained. Single-crystal analysis revealed that compounds 1 and 2 feature two-dimensional (2D) layer structure with opened widows occupied by guests (DMF for 1 and DMA for 2). In addition, a rare hybrid [(H2O)3(DMA)2] pentamer was found in 2. Furthermore, thermal analyses of 1-2 were also investigated.

  7. GD SDR Automatic Gain Control Characterization Testing

    NASA Technical Reports Server (NTRS)

    Nappier, Jennifer M.; Briones, Janette C.

    2013-01-01

    The General Dynamics (GD) S-Band software defined radio (SDR) in the Space Communications and Navigation (SCAN) Testbed on the International Space Station (ISS) will provide experimenters an opportunity to develop and demonstrate experimental waveforms in space. The GD SDR platform and initial waveform were characterized on the ground before launch and the data will be compared to the data that will be collected during on-orbit operations. A desired function of the SDR is to estimate the received signal to noise ratio (SNR), which would enable experimenters to better determine on-orbit link conditions. The GD SDR does not have an SNR estimator, but it does have an analog and a digital automatic gain control (AGC). The AGCs can be used to estimate the SDR input power which can be converted into a SNR. Tests were conducted to characterize the AGC response to changes in SDR input power and temperature. This purpose of this paper is to describe the tests that were conducted, discuss the results showing how the AGCs relate to the SDR input power, and provide recommendations for AGC testing and characterization.

  8. Dispersion of Anomalous Azimuthal Rotation and Circular Extinction Contrast in Dyed K2SO4 Crystals

    E-print Network

    Kaminsky, Werner

    Dispersion of Anomalous Azimuthal Rotation and Circular Extinction Contrast in Dyed K2SO4 Crystals Wiley-Liss, Inc. KEY WORDS: dyed crystals; K2SO4; Trypan blue; azimuthal rotation; circular extinction

  9. August 15, 2013 Tuberculosis (TB) Skin Test Solution Shortage and Ramifications

    E-print Network

    Zhou, Yaoqi

    will be performed with interferon gamma release assays (IGRAs), blood tests for TB, rather than TSTs 2. Annual TB. Annual TB surveillance requiring a symptom questionnaire or IGRA will continue as usual. IUPUI Health

  10. 46 CFR 35.40-30 - Instructions for changing steering gear-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Instructions for changing steering gear-TB/ALL. 35.40-30 Section 35.40-30... Posting and Marking Requirements-TB/ALL. § 35.40-30 Instructions for changing steering gear—TB/ALL. Instructions in at least...

  11. 46 CFR 35.40-30 - Instructions for changing steering gear-TB/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Instructions for changing steering gear-TB/ALL. 35.40-30 Section 35.40-30... Posting and Marking Requirements-TB/ALL § 35.40-30 Instructions for changing steering gear—TB/ALL. Instructions in at least...

  12. 46 CFR 35.40-30 - Instructions for changing steering gear-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Instructions for changing steering gear-TB/ALL. 35.40-30 Section 35.40-30... Posting and Marking Requirements-TB/ALL. § 35.40-30 Instructions for changing steering gear—TB/ALL. Instructions in at least...

  13. 46 CFR 35.40-30 - Instructions for changing steering gear-TB/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...Instructions for changing steering gear-TB/ALL. 35.40-30 Section 35.40-30... Posting and Marking Requirements-TB/ALL § 35.40-30 Instructions for changing steering gear—TB/ALL. Instructions in at least...

  14. 46 CFR 35.40-30 - Instructions for changing steering gear-TB/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...Instructions for changing steering gear-TB/ALL. 35.40-30 Section 35.40-30... Posting and Marking Requirements-TB/ALL § 35.40-30 Instructions for changing steering gear—TB/ALL. Instructions in at least...

  15. Dy-Free Nd-Fe-B Based Permanent Magnets

    NASA Astrophysics Data System (ADS)

    Pathak, Arjun; Khan, Mahmud; Gschneidner, Karl, Jr.; McCallum, Ralph; Pecharsky, Vitalij

    2015-03-01

    Nd2Fe14B based permanent magnets are the current state of the art for high performance magnets. The prototype crystallize in the P42 / mnm tetragonal crystal structure, where the Nd atoms occupy the 4f and 4gsites, Fe atoms occupy six different atomic sites (16k1, 16k2, 8j1, 8j2, 4e, 4c), and B occupies only the 4g site. The leading contribution to the magnetocrystalline anisotropy in Nd2Fe14B energy comes from the Nd ions, which strongly prefer a c-axis alignment at ambient temperature. Nd2Fe14B permanent magnet has excellent magnetic properties at room temperature but has poor high temperature properties (T>400 K). A small amount of Dy (up to 10%) is substituted for Nd in Nd2Fe14B to increase the high temperature performance. Although Dy containing Nd2Fe14B magnets are desired for high temperature applications, the high price and limited supply of Dy urges the development of Dy-free permanent magnets. Here, we discuss the magnetic properties of several Dy-free Nd-Fe-B based nanostructured magnets and propose alternatives for Dy-based Nd2Fe14B permanent magnets for high temperature applications such as electric drive motors and wind turbines. This work was supported by the U.S.DOE, ARPA-E, Rare Earth Alternatives in Critical Technologies for Energy (REACT). The research was performed at the Ames Laboratory which is operated for the U.S. DOE by Iowa State University under contract #DE-AC02-07CH11358.

  16. Subtilisin DY—Kinetic characterization and comparison with related proteinases

    Microsoft Academic Search

    Klaus Peters; Dorothea Pauli; Helmer Hache; Raina N. Boteva; Nicolay C. Genov; Siegfried Fittkau

    1989-01-01

    Subtilisin DY, a serine proteinase fromBacillus subtilis, variant DY, is compared with subtilisin Carlsberg, proteinase K, thermitase, as well as with a-chymotrypsin by use of kinetic parameters of the reactions with the synthetic peptidyl substrates succinyl-Ala3-4-nitroanilide, succinyl-Ala2-Phe-4-nitroanilide, MeO-succinyl-Ala2-Phe-4-nitroanilide, and with the irreversible inhibitors of the general structure benzyloxycarbonyl-Alan-PheCH2Cl (n=0, 1, 2, 3, 4) and benzyloxycarbonyl-Ala-AaCH2Cl (Aa=Gly, Ala, Val, Leu, Phe),

  17. Optical properties of lead borate glasses containing Dy3+ ions

    Microsoft Academic Search

    Joanna Pisarska

    2009-01-01

    Optical properties of lead borate glasses containing Dy3+ ions were examined using absorption and luminescence measurements and theoretical calculations based on the Judd-Ofelt framework and the Inokuti-Hirayama model. The luminescence spectra show two characteristic bands at 480 and 573 nm, which are due to 4F9\\/2-6H15\\/2 (blue) and 4F9\\/2-6H13\\/2 (yellow) transitions of trivalent Dy3+ ions. The yellow\\/blue luminescence and its decay

  18. Optical absorption and fluorescence properties of Dy3+: SFB glasses

    Microsoft Academic Search

    D. Uma Maheswari; J. Suresh Kumar; T. Sasikala; A. Mohan Babu; K. Pavani; Kiwan Jang; L. Rama Moorthy

    2009-01-01

    This paper presents the preparation and spectroscopic characterization of Dy3+-doped sodium fluoroborate (SFB) glasses of the type (50-x) B2O3 + 25 Na2O + 10 CaF2 + 10 AlF3 + 5 LaF3 + x DyF3 (x = 0.01, 0.1, 0.5,1.0, 2.0 and 4.0 mol%). By measuring the area under absorption bands, the experimental oscillator strengths are determined. The Judd-Ofelt (J-O) intensity

  19. 46 CFR 30.10-45 - Ocean-TB/O.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 2013-10-01 false Ocean-TB/O. 30.10-45 Section 30...PROVISIONS Definitions § 30.10-45 Ocean—TB/O. Under this designation...vessels normally navigating the waters of any ocean or the Gulf of Mexico more than 20...

  20. 46 CFR 30.10-45 - Ocean-TB/O.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false Ocean-TB/O. 30.10-45 Section 30...PROVISIONS Definitions § 30.10-45 Ocean—TB/O. Under this designation...vessels normally navigating the waters of any ocean or the Gulf of Mexico more than 20...

  1. 46 CFR 30.10-45 - Ocean-TB/O.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false Ocean-TB/O. 30.10-45 Section 30...PROVISIONS Definitions § 30.10-45 Ocean—TB/O. Under this designation...vessels normally navigating the waters of any ocean or the Gulf of Mexico more than 20...

  2. Influence of the rare earth concentration on the crystallization process of Fe-Dy-B amorphous alloys. Study of Fe74Dy6B20 and Fe70Dy10B20 alloys

    Microsoft Academic Search

    G. Ravach; F. Machizaud; J. Teillet; J. M. LeBreton; A. Fnidiki

    2000-01-01

    The crystallization behaviour of Fe74 Dy6 B20 and Fe70 Dy10 B20 amorphous alloys was carefully investigated by differential scanning calorimetry, Mössbauer spectrometry and x-ray diffraction up to 800 °C. Calorimetric studies were performed in limited temperature ranges that were progressively extended. For Fe74 Dy6 B20 , after partial crystallization into the tetragonal Fe3 B compound, the remaining amorphous part segregates

  3. Crystal structure and magnetic properties of GdSi1.78, Gd(Si0.684Ge0.316)1.78, GdGe1.57, and GdSn2 compounds

    NASA Astrophysics Data System (ADS)

    Zou, J. D.; Liu, J.; Yan, M.

    2015-07-01

    Intermetallic compounds of Gd with Si, Ge, and Sn near 1:2 stoichiometry adopt several closely related crystal structures. We find that GdSi1.78 and Gd(Si0.684Ge0.316)1.78 crystallize in the same GdSi1.4-type orthorhombic structure (space group Imma), while GdGe1.57 and GdSn2 adopt ?-ThSi2-type tetragonal structure (space group I41/amd) and ZrSi2-type orthorhombic structure (space group Cmcm), respectively. All compounds order antiferromagnetically; their Néel temperatures are only weakly affected by the magnetic field of less than 50 kOe. Unusual features are observed including multiple phase transitions and thermomagnetic irreversibilities.

  4. Latent TB Infection Diagnosis in Population Exposed to TB Subjects in Close and Poor Ventilated High TB Endemic Zone in India

    PubMed Central

    Kashyap, Rajpal S.; Nayak, Amit R.; Gaherwar, Hari M.; Husain, Aliabbas A.; Shekhawat, Seema D.; Jain, Ruchika K.; Panchbhai, Milind S.; Raje, Dhananjay V.; Purohit, Hemant J.; Taori, Girdhar M.; Daginawala, Hatim F.

    2014-01-01

    Background The present study was designed to investigate the utility of Quantiferon TB gold (QFT-G) and Tuberculin skin test (TST) for diagnosis of latent TB infection (LTBI) in high crowding TB endemic zone of Nagpur, India and their comparison with associated risk factors. Methods Out of 342 eligible participants, QFT-G and TST were performed in 162 participants. Results The prevalence of LTBI observed according to QFT-G and TST was 48% and 42% respectively, with an agreement of 52.47%. QFT-G positivity was associated with age while TST positivity was associated with body mass index (BMI). Duration of exposure emerged as a key risk factor significantly associated with both the tests. Conclusion The prevalence of LTBI was quite high in the studied zone as detected by both the evaluated tests and thus, the combination of both the tests will be best predictive for LTBI in such high TB endemic regions. PMID:24614179

  5. Magnetic resonance in multilayer Gd\\/Si\\/Co magnetic films

    Microsoft Academic Search

    G. S. Patrin; V. O. Vas’kovskii; A. V. Svalov; E. V. Eremin; M. A. Panova; V. N. Vasil’ev

    2006-01-01

    The magnetic properties of multilayer Gd\\/Si\\/Co magnetic films are experimentally studied by electron magnetic resonance and\\u000a analyzed theoretically. The introduction of a semiconductor silicon interlayer is found to substantially affect the magnetic\\u000a interlayer coupling and the magnetic dynamics of the system. The interlayer coupling is shown to be ferromagnetic for the\\u000a (Gd\\/Si)n films and to be antiferromagnetic for the (Gd\\/Si\\/Co\\/Si)n

  6. In 1997, the maize gene tb1 was reported as the first domestication QTL to be cloned (4). tb1

    E-print Network

    Forbes, Jeffrey

    In 1997, the maize gene tb1 was reported as the first domestication QTL to be cloned (4). tb1 grains to maize (as opposed to the covered grains of teosinte), was cloned (6).And thus far in 2006, in addition to the two rice shattering genes, cloning of the wheat Q gene was reported (7). Q controls

  7. Drug Therapy of Experimental Tuberculosis (TB): Improved Outcome by Combining SQ109, a New Diamine Antibiotic, with Existing TB Drugs?

    PubMed Central

    Nikonenko, Boris V.; Protopopova, Marina; Samala, Rowena; Einck, Leo; Nacy, Carol A.

    2007-01-01

    Substitution of the new diamine antibiotic SQ109 for ethambutol in a mouse model of chronic tuberculosis (TB) improved efficacy of combination drug therapy with first-line TB drugs rifampin and isoniazid, with or without pyrazinamide: at 8 weeks, lung bacteria were 1.5 log10 lower in SQ109-containing regimens. PMID:17242141

  8. Drug therapy of experimental tuberculosis (TB): improved outcome by combining SQ109, a new diamine antibiotic, with existing TB drugs.

    PubMed

    Nikonenko, Boris V; Protopopova, Marina; Samala, Rowena; Einck, Leo; Nacy, Carol A

    2007-04-01

    Substitution of the new diamine antibiotic SQ109 for ethambutol in a mouse model of chronic tuberculosis (TB) improved efficacy of combination drug therapy with first-line TB drugs rifampin and isoniazid, with or without pyrazinamide: at 8 weeks, lung bacteria were 1.5 log10 lower in SQ109-containing regimens. PMID:17242141

  9. Electronic specific heat coefficient and magnetic entropy of icosahedral Mg-RE-Zn (RE=Gd, Tb and Y) quasicrystals

    Microsoft Academic Search

    Y. Hattori; K. Fukamichi; K. Suzuki; A. Niikura; A. P. Tsai; A. Inoue; T. Masumoto

    1995-01-01

    The low-temperature specific heat for non-magnetic Mg42Y8Zn50 quasicrystal has been investigated to get information on the electronic structure. The electronic specific heat coefficient gamma is estimated to be 0.63 mJ mol-1 K-2, which is about 70% of the value expected from the free-electron model. This small gamma value strongly suggests the existence of a pseudogap of the electronic density of

  10. Cross section measurement of the 159Tb(n, ?)Tb160 nuclear reaction

    NASA Astrophysics Data System (ADS)

    Dzysiuk, N.; Kadenko, I.; Gressier, V.; Koning, A. J.

    2015-04-01

    The cross section of the 159Tb(n, ?)Tb160 reaction was measured in four mono-energetic neutron fields of energy 3.7, 4.3, 5.4, and 6.85 MeV, respectively, with the activation technique applied to metal discs of natural composition. To ensure an acceptable precision of the results all major sources of uncertainties were taken into account. Calculations of detector efficiency, incident neutron spectrum and correction factors were performed with the Monte Carlo code (MCNPX), whereas theoretical excitation functions were calculated with the TALYS-1.2 code and compared to the experimental cross section values. This paper presents both measurements and calculation leading to the cross section values.

  11. Prevalence of pulmonary TB and spoligotype pattern of Mycobacterium tuberculosis among TB suspects in a rural community in Southwest Ethiopia

    PubMed Central

    2012-01-01

    Background In Ethiopia where there is no strong surveillance system and state of the art diagnostic facilities are limited, the real burden of tuberculosis (TB) is not well known. We conducted a community based survey to estimate the prevalence of pulmonary TB and spoligotype pattern of the Mycobacterium tuberculosis isolates in Southwest Ethiopia. Methods A total of 30040 adults in 10882 households were screened for pulmonary TB in Gilgel Gibe field research centre in Southwest Ethiopia. A total of 482 TB suspects were identified and smear microscopy and culture was done for 428 TB suspects. Counseling and testing for HIV/AIDS was done for all TB suspects. Spoligotyping was done to characterize the Mycobacterium tuberculosis isolates. Results Majority of the TB suspects were females (60.7%) and non-literates (83.6%). Using smear microscopy, a total of 5 new and 4 old cases of pulmonary TB cases were identified making the prevalence of TB 30 per 100,000. However, using the culture method, we identified 17 new cases with a prevalence of 76.1 per 100,000. There were 4.3 undiagnosed pulmonary TB cases for every TB case who was diagnosed through the passive case detection mechanism in the health facility. Eleven isolates (64.7%) belonged to the six previously known spoligotypes: T, Haarlem and Central-Asian (CAS). Six new spoligotype patterns of Mycobacterium tuberculosis, not present in the international database (SpolDB4) were identified. None of the rural residents was HIV infected and only 5 (5.5%) of the urban TB suspects were positive for HIV. Conclusion The prevalence of TB in the rural community of Southwest Ethiopia is low. There are large numbers of undiagnosed TB cases in the community. However, the number of sputum smear-positive cases was very low and therefore the risk of transmitting the infection to others may be limited. Active case finding through health extension workers in the community can improve the low case detection rate in Ethiopia. A large scale study on the genotyping of Mycobacterium tuberculosis in Ethiopia is crucial to understand transmission dynamics, identification of drug resistant strains and design preventive strategies. PMID:22414165

  12. Effect of Al2Gd on microstructure and properties of laser clad Mg-Al-Gd coatings

    NASA Astrophysics Data System (ADS)

    Chen, Hong; Zhang, Ke; Yao, Chengwu; Dong, Jie; Li, Zhuguo; Emmelmann, Claus

    2015-03-01

    In order to investigate the effects of Gd addition on the microstructures and properties of magnesium coatings, the Mg-7.5Al-xGd (x = 0, 2.5, 5.0 and 7.5 wt.%) coatings on cast magnesium alloy were fabricated by laser cladding with wire feeding. The results indicated that the gadolinium (Gd) addition led to the formation of a cubic Al2Gd phase as well as suppressed the precipitation of eutectic Mg17Al12 phase. The laser clad coating containing nominally 7.5 wt.% Gd presented the highest microhardness, ultimate tensile strength and yield strength at both room temperature and high temperatures. The enhancement of heat resistant capacities was chiefly attributed to the existence of thermally stable Al2Gd particles, which prevented tiny liquation of eutectic phases along the grain boundaries and made great contributions on maintaining high yield ratio during high-temperature deformation.

  13. Localization of the Gangliosides GD2 and GD3 in Adhesion Plaques and on the Surface of Human Melanoma Cells

    NASA Astrophysics Data System (ADS)

    Cheresh, David A.; Harper, John R.; Schulz, Gregor; Reisfeld, Ralph A.

    1984-09-01

    The predominant gangliosides produced by two cultured human melanoma cell lines are GD3 and/or GD2. These gangliosides were found to be cell associated and present in substratum-attached material after cell removal by EDTA. Monoclonal antibodies directed to GD2 and GD3 specified the cell-surface distribution of these gangliosides and localized them in focal adhesion plaques at the interface of cells and their substratum. These attachment sites did not represent indiscriminant membrane fragments remaining after removal of cells with EDTA, because neither melanoma-associated proteoglycan nor class I histocompatibility antigens were detected by their respective antibodies. Our data suggest that the disialogangliosides GD2 and GD3 may be involved in the interaction between human melanoma cells and solid substrata.

  14. DyKnow Federations: Distributing and Merging Information Among UAVs

    E-print Network

    Doherty, Patrick

    DyKnow Federations: Distributing and Merging Information Among UAVs Fredrik Heintz and Patrick, patdo}@ida.liu.se Abstract--As unmanned aerial vehicle (UAV) applications be- come more complex and versatile there is an increasing need to allow multiple UAVs to cooperate to solve problems which are beyond

  15. Magnetic structure of the intermetallic compound DyAg

    Microsoft Academic Search

    T. Kaneko; H. Yoshida; M. Ohashi; S. Abe

    1987-01-01

    Neutron diffraction measurements were performed for an antiferromagnetic compound DyAg with TN=56.7 K. Magnetic structures were found to be the (pi pi 0)-type at 12 K and rthe sinusoidally modulated transverse static spin wave propagating along the direction and polarized in the direction at 50.7 K.

  16. Magnetic Behavior of a Dy8 Molecular Nanomagnet

    NASA Astrophysics Data System (ADS)

    Zhang, Qing; Sarachik, Myriam; Baker, Michael; Chen, Yizhang; Kent, Andrew; Stamatatos, Theocharis

    2015-03-01

    As part of a study of quantum tunneling in a newly synthesized family of dysprosium-based molecular magnets that exhibit a chiral spin structure, we report initial investigations of the magnetic response of a Dy8 cluster with the formula (Et4N)4[Dy8O(nd)8(NO3)10(H2O)2] .2MeCN. The molecular complex contains triangular arrangements of exchange coupled Dy(III) ions. The compound forms an approximate snub-square Archimedean lattice unit. The measured magnetization of this network of four triangles suggests the presence of multiple spin chiral vortexes. Single crystal susceptibility and magnetization measurements indicate the presence of a hard-axis direction and an easy plane. These principal orientations have been investigated in magnetic fields up to 5 Tesla for temperatures between 1.8 and 100 K using a SQUID-based Quantum Design MPMS magnetometer. Complex easy plane magnetic hysteresis loops emerge at lower temperatures measured using Hall probe magnetometry at sub 1 K temperatures. The analysis of these measurements will be discussed and compared with results of theoretical calculations. Work supported by ARO W911NF-13-1-1025 (CCNY), NSF-DMR-1309202 (NYU); the synthesis of the Dy8 cluster was supported by NSERC (Discovery grant to Th.C.S.).

  17. Structural and phase dependent thermo and photoluminescent properties of Dy(OH){sub 3} and Dy{sub 2}O{sub 3} nanorods

    SciTech Connect

    Chandrasekhar, M. [Prof. C.N.R. Rao centre for Nano Research (CNR), Tumkur University, Tumkur 572103 (India) [Prof. C.N.R. Rao centre for Nano Research (CNR), Tumkur University, Tumkur 572103 (India); Department of Physics, Acharya Institute of Technology, Bangalore 560090 (India); Sunitha, D.V. [Prof. C.N.R. Rao centre for Nano Research (CNR), Tumkur University, Tumkur 572103 (India)] [Prof. C.N.R. Rao centre for Nano Research (CNR), Tumkur University, Tumkur 572103 (India); Dhananjaya, N. [Department of Physics, B.M.S. Institute of Technology, Bangalore 560064 (India)] [Department of Physics, B.M.S. Institute of Technology, Bangalore 560064 (India); Nagabhushana, H., E-mail: bhushanvl@gmail.com [Prof. C.N.R. Rao centre for Nano Research (CNR), Tumkur University, Tumkur 572103 (India); Sharma, S.C. [Prof. C.N.R. Rao centre for Nano Research (CNR), Tumkur University, Tumkur 572103 (India)] [Prof. C.N.R. Rao centre for Nano Research (CNR), Tumkur University, Tumkur 572103 (India); Nagabhushana, B.M. [Department of Chemistry, M.S. Ramaiah Institute of Technology, Bangalore 560054 (India)] [Department of Chemistry, M.S. Ramaiah Institute of Technology, Bangalore 560054 (India); Shivakumara, C. [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012 (India)] [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012 (India); Chakradhar, R.P.S. [National Aerospace Laboratories (CSIR), Bangalore 560017 (India)] [National Aerospace Laboratories (CSIR), Bangalore 560017 (India)

    2012-08-15

    Graphical abstract: Packing diagram of (a) hexagonal Dy(OH){sub 3} and (b) cubic Dy{sub 2}O{sub 3} nanorods. Highlights: ? Hexagonal Dy(OH){sub 3} and Dy{sub 2}O{sub 3} nanorods were prepared by hydrothermal route. ? Phase dependent PL and TL studies were carried out. ? The kinetic parameters such as activation energy (E), order of kinetics (b), and frequency factor (s) were estimated using peak shape method. ? Linear response of cubic Dy{sub 2}O{sub 3} phase is useful for its application in dosimetry. -- Abstract: Hexagonal Dy(OH){sub 3} and cubic Dy{sub 2}O{sub 3} nanorods were prepared by hydrothermal method. Dy(OH){sub 3} nanorods was directly obtained at 180 °C for 20 h after hydrothermal treatment whereas subsequently heat treatment at 750 °C for 2 h gives pure cubic Dy{sub 2}O{sub 3}. SEM micrographs reveal that needle shaped rods with different sizes were observed in both the phases. TEM results also confirm this. The TL response of hexagonal Dy(OH){sub 3} and cubic Dy{sub 2}O{sub 3} nanorods have been analyzed for ?-irradiation over a wide range of exposures (1–5 kGy). TL glow peak intensity increases with ? dose in both the phases. The activation energy (E), order of kinetics (b), and frequency factor (s) for both the phases have been determined using Chen's peak shape method. The simple glow curve shape, structure and linear response to ?-irradiation over a large span of exposures makes the cubic Dy{sub 2}O{sub 3} as a useful dosimetric material to estimate high exposures of ?-rays.

  18. Structure and magnetic properties of bulk nanocrystalline Dy metal prepared by spark plasma sintering

    SciTech Connect

    Yue, M.; Wang, K. J.; Liu, W. Q.; Zhang, D. T.; Zhang, J. X. [The Key Laboratory of Advanced Functional Materials, Ministry of Education, and College of Materials Science and Engineering, Beijing University of Technology, Beijing 100022 (China)

    2008-11-17

    The structure and magnetic properties were studied for bulk nanocrystalline dysprosium (Dy) metal prepared by spark plasma sintering method. All the as-prepared samples have hexagonal close packed structure. A decrease in grain size results in remarkable changes in magnetic ordering temperature of the nanocrystalline Dy metal. At 5 K, the magnetization drops by 3.35%, and the coercive force increases by three times for nanocrystalline Dy compared to those of coarse-grained bulk Dy sample. These results indicate the remarkable influence of the nanostructure on the magnetism of Dy due to finite size effect.

  19. Photoluminescence and energy transfer study of Er3+ and Dy3+ codoped tellurite glasses.

    PubMed

    Zhang, Feng; Xiao, Zhisong; Zhu, Fang; Yan, Lu; Zhou, Bo; Huang, Anping

    2011-12-01

    Photoluminescence properties of the Er(3+)-Dy3+ codoped tellurite glasses were studied by absorption and visible emission spectra, which revealed luminescence bands of both Er3+ and Dy3+ when pumping with the wavelength of 325 nm. The concentration quenching occurred as Dy3+ concentration increased beyond 3 mol%. The dependence of Er3+ characteristic emission on Dy3+ concentration indicated energy transfer process between Er3+ and Dy3+. The chromaticity coordinates of these glasses are close to white light, which implies that these glasses might be potential candidates for white lighting through an appropriate combination. PMID:22409022

  20. Octa­deca­bromidobis(dicarbido)deca­dysprosium, [Dy10Br18(C2)2

    PubMed Central

    Daub, Kathrin; Meyer, Gerd

    2008-01-01

    Single crystals of [Dy10Br18(C2)2] were obtained during the reaction of DyBr3 with dysprosium metal and graphite in a sealed tantalum container. In the crystal structure, the Dy atoms form dimers of edge-sharing octa­hedra, each encapsulating a C2 unit. The metal atoms are surrounded by Br atoms above the cluster edges and vertices, respectively. The dimers are connected to each other by Br atoms, leading to a three-dimensional network. [Dy10Br18(C2)2] is isotypic with its iodido analogue [Dy10I18(C2)2]. PMID:21200454

  1. Tuberculosis specific responses following therapy for TB: Impact of HIV co-infection.

    PubMed

    Siddiqui, S; Sarro, Y; Diarra, B; Diallo, H; Guindo, O; Dabitao, D; Tall, M; Hammond, A; Kassambara, H; Goita, D; Dembele, P; Traore, B; Hengel, R; Nason, M; Warfield, J; Washington, J; Polis, M; Diallo, S; Dao, S; Koita, O; Lane, H C; Catalfamo, M; Tounkara, A

    2015-07-01

    Characterizing perturbations in the immune response to tuberculosis in HIV can develop insights into the pathogenesis of coinfection. HIV+ TB+ and TB monoinfected (TB+) subjects recruited from clinics in Bamako prior to initiation of TB treatment were evaluated at time-points following initiation of therapy. Flow cytometry assessed CD4+/CD8+ T cell subsets and activation markers CD38/HLA-DR. Antigen specific responses to TB proteins were assessed by intracellular cytokine detection and proliferation. HIV+ TB+ subjects had significantly higher markers of immune activation in the CD4+ and CD8+ T cells compared to TB+ subjects. HIV+ TB+ had lower numbers of TB-specific CD4+ T cells at baseline. Plasma IFN? levels were similar between HIV+ TB+ and TB+ subjects. No differences were observed in in-vitro proliferative capacity to TB antigens between HIV+ TB+ and TB+ subjects. Subjects with HIV+ TB+ coinfection demonstrate in vivo expansion of TB-specific CD4+ T cells. Immunodeficiency associated with CD4+ T cell depletion may be less significant compared to immunosuppression associated with HIV viremia or untreated TB infection. PMID:25889622

  2. New drugs and regimens for treatment of TB.

    PubMed

    Leibert, Eric; Rom, William N

    2010-07-01

    Tools for effective TB control have been available for years. Case finding, active medications, case management and directly observed therapy are the foundations for the management of TB. The current TB epidemic, centered in resource-limited settings is fueled by the HIV-1 epidemic. Lack of ability to diagnose and treat drug-resistant TB has led to development of more extensive patterns of resistance. Among the currently available drugs, there is reason to hope that rifamycins paired with fluoroquinolones will lead to shorter treatment regimens for drug-susceptible TB. As the result of novel public-private collaborations and investments of resources, new drugs are being developed. These include TMC207, already shown to have activity early in the treatment of multidrug-resistant TB and others that are likely to be active against persistor organisms, and have the prospect to dramatically shorten treatment courses for active and latent TB. Given that these drugs have novel mechanisms of action, combinations have the prospect to be highly active even against multidrug-resistant organisms. PMID:20586565

  3. New drugs and regimens for treatment of TB

    PubMed Central

    Leibert, Eric; Rom, William N

    2013-01-01

    Tools for effective TB control have been available for years. Case finding, active medications, case management and directly observed therapy are the foundations for the management of TB. The current TB epidemic, centered in resource-limited settings is fueled by the HIV-1 epidemic. Lack of ability to diagnose and treat drug-resistant TB has led to development of more extensive patterns of resistance. Among the currently available drugs, there is reason to hope that rifamycins paired with fluoroquinolones will lead to shorter treatment regimens for drug-susceptible TB. As the result of novel public-private collaborations and investments of resources, new drugs are being developed. These include TMC207, already shown to have activity early in the treatment of multidrug-resistant TB and others that are likely to be active against persistor organisms, and have the prospect to dramatically shorten treatment courses for active and latent TB. Given that these drugs have novel mechanisms of action, combinations have the prospect to be highly active even against multidrug-resistant organisms. PMID:20586565

  4. Spectroscopic studies of interactions involving horseradish peroxidase and Tb3+.

    PubMed

    Guo, Shaofen; Zhou, Qing; Lu, Tianhong; Ding, Xiaolan; Huang, Xiaohua

    2008-09-01

    The spectroscopic properties of interactions involving horseradish peroxidase (HRP) and Tb3+ in the simulated physiological solution was investigated with some electrochemical and spectroscopic methods, such as cyclic voltammetry (CV), circular dichroism (CD), X-ray photoelectron spectroscopy (XPS) and synchronous fluorescence (SF). It was found that Tb3+ can coordinate with oxygen atoms in carbonyl groups in the peptide chain of HRP, form the complex of Tb3+ and HRP (Tb-HRP), and then lead to the conformation change of HRP. The increase in the random coil content of HRP can disturb the microstructure of the heme active center of HRP, in which the planarity of the porphyrin cycle in the heme group is increased and then the exposure extent of the electrochemical active center is decreased. Thus Tb3+ can inhibit the electrochemical reaction of HRP and its electrocatalytic activity for the reduction of H2O2 at the Au/Cys/GC electrode. The changes in the microstructure of HRP obstructed the electron transfer of Fe(III) in the porphyrin cycle of the heme group, thus HRP catalytic activity is inhibited. The inhibition effect of Tb3+ on HRP catalytic activity is increased with the increasing of Tb3+ concentration. This study would provide some references for better understanding the rare earth elements and heavy metals on peroxidase toxicity in living organisms. PMID:18024195

  5. Collectivity of 0+ states in 160Gd

    NASA Astrophysics Data System (ADS)

    Lesher, S. R.; Casarella, C.; Aprahamian, A.; Crider, B. P.; Ikeyama, R.; Marsh, I. R.; McEllistrem, M. T.; Peters, E. E.; Prados-Estévez, F. M.; Smith, M. K.; Tully, Z. R.; Vanhoy, J. R.; Yates, S. W.

    2015-05-01

    Excited 0+ states in 160Gd have been examined with the (n ,n'? ) reaction at incident neutron energies up to 2.8 MeV. Gamma-ray excitation functions and angular distribution measurements allow the confirmation of the existence of 0+ states at 1379.70 keV and 1558.30 keV, but we reject the assignments of additional previously suggested 0+ candidates. Limits on the level lifetimes of the observed 0+ states permit an evaluation of the collectivity of these states.

  6. Multiferroic Behavior of Gd Based Manganite

    Microsoft Academic Search

    S. Sagar; P. A. Joy; M. R. Anantharaman

    2009-01-01

    Here we report the multiferroic nature of charge ordered manganite\\u000a Gd0.5Sr0.5MnO3 for the first time. The temperature variation of\\u000a dielectric constant shows broad relaxor type ferroelectric transition at\\u000a around 210K and magnetization measurements shows weak ferromagnetism at\\u000a 50K. The dielectric peak is very close to charge ordering temperature\\u000a which is an evidence of the link between electronic state and increase

  7. Double-Beta Decay of 96Zr and Double-Electron Capture of 156Dy to Excited Final States

    NASA Astrophysics Data System (ADS)

    Finch, Sean W.

    Two separate experimental searches for second-order weak nuclear decays to excited final states were conducted. Both experiments were carried out at the Kimballton Underground Research Facility to provide shielding from cosmic rays. The first search is for the two-neutrino double-beta decay of 96Zr to excited final states of the daughter nucleus, 96Mo. As a by product of this experiment, the beta decay of 96Zr was also investigated. Two coaxial high-purity germanium detectors were used in coincidence to detect gamma rays produced by the daughter nucleus as it de-excited to the ground state. After collecting 1.92 years of data with 17.91 g of enriched 96Zr, half-life limits at the level of 10 20 yr were produced. Measurements of this decay are important to test neutrinoless double-beta decay nuclear matrix element calculations, which are necessary to extract the neutrino mass from a measurement of the neutrinoless double-beta decay half-life. The second experiment is a search for the resonantly-enhanced neutrinoless double-electron capture decay of 156Dy to excited states in 156Gd. Double-electron capture is a possible experimental alternative to neutrinoless-double beta decay, which could distinguish the Dirac or Majorana nature of the neutrino. Two clover high-purity germanium detectors were used in coincidence to investigate the decay. A 213.5 mg enriched 156Dy sample was observed for 0.635 year, producing half-life limits of 10 17 yr. The limits produced by both of these experiments are currently the most stringent limits available for these decays.

  8. TB tracer teams in South Africa: knowledge, practices and challenges of tracing TB patients to improve adherence

    PubMed Central

    2013-01-01

    Background In 2008–2009 the South African National Tuberculosis (TB) Program (NTP) implemented a national pilot project, the TB Tracer Project, aiming to decrease default rates and improve patient outcomes. The current study aimed to inform the NTP by describing the knowledge, attitudes, and practices of TB program personnel involved with tracing activities. Methods A self-administered written questionnaire was sent to TB staff, managers and tracer team leaders to assess basic TB knowledge, attitudes and practices. Descriptive statistics were used to summarize results and the chi-squared statistic was used to compare responses of staff at facilities that participated in the TB Tracer Project (tracer) and those that followed standard NTP care (non-tracer). Results Of 560 total questionnaires distributed, 270 were completed and returned (response rate 48%). Total TB knowledge ranged from 70.8-86.3% correct across all response groups. However, just over half (range 50–59.3%) of each respondent group was able to correctly identify the four components of a DOT encounter. A patient no longer feeling sick was cited by 72.1% of respondents as the reason patients fail to adhere to treatment. Tracer teams were viewed as an effective means to get patients to return to treatment by 96.3% of health facility level respondents. Tracer team leaders reported concerns including lack of logistical support (41.7%), insufficient physical safety precautions (41.7%), and inadequate protection from contracting TB (39.1%). Upon patients returning to treatment at the clinic, facilities included in the TB Tracer Project were significantly more likely to discuss alternate DOTS arrangements than non-tracer facilities (79.2 vs. 66.4%, p?=?0.03). Conclusions This study identified key components of knowledge, attitudes, and practices regarding TB patient tracing activities in South Africa. Educating patients on the essential need to complete treatment irrespective of clinical symptoms may help improve treatment adherence. Future scale-up and integration of TB tracing activities as part of standard TB management should include provisions for standardized training of personnel on the critical elements of DOTS, and for ensuring appropriate supervision, logistical support, and physical safety and TB transmission protection of tracing teams. PMID:24007294

  9. Redetermination of Dy3Ni from single-crystal X-ray data

    PubMed Central

    Levytskyy, Volodymyr; Babizhetskyy, Volodymyr; Kotur, Bohdan; Smetana, Volodymyr

    2013-01-01

    The classification of the title compound, tridysprosium nickel, into the Fe3C (or Al3Ni) structure type has been deduced from powder X-ray diffraction data with lattice parameters reported in a previous study [Lemaire & Paccard (1967 ?). Bull. Soc. Fr. Mineral. Cristallogr. 40, 311–315]. The current re-investigation of Dy3Ni based on single-crystal X-ray data revealed atomic positional parameters and anisotropic displacement parameters with high precision. The asymmetric unit consists of two Dy and one Ni atoms. One Dy atom has site symmetry .m. (Wyckoff position 4c) and is surrounded by twelve Dy and three Ni atoms. The other Dy atom (site symmetry 1, 8d) has eleven Dy and three Ni atoms as neighbours, forming a distorted Frank–Kasper polyhedron. The coordination polyhedron of the Ni atom (.m., 4c) is a tricapped trigonal prism formed by nine Dy atoms. PMID:24454015

  10. MICROBIOLOGY: Enhanced: TB--A New Target, a New Drug

    NSDL National Science Digital Library

    Stewart T. Cole (Institut Pasteur; Génétique Moléculaire Bactérienne and Biochimie Structurale Units)

    2005-01-14

    Access to the article is free, however registration and sign-in are required. Tuberculosis (TB) kills 2 million people annually worldwide and imposes huge costs on communities, particularly those in developing countries. Yet no new drugs for TB have been discovered in the past 40 years. This is set to change, as Cole and Alzari report in their Perspective, with the discovery of a diarylquinoline compound that is highly active against a broad range of mycobacterial species including both the drug-sensitive and drug-resistant forms of M. tuberculosis, the bacterium that causes TB (Andries et al.).

  11. Perpendicular anisotropy in the amorphous TbCo/Si multilayers

    NASA Astrophysics Data System (ADS)

    Chen, X.; Wang, Y. J.; Liang, B. Q.; Tang, Y. J.; Zhao, H. W.; Xiao, J. Q.

    2000-05-01

    The TbCo/Si multilayers prepared by the rf magnetron sputtering system with various Si thickness have been investigated. X-ray diffraction, magnetic measurement and Kerr rotation have been performed. No antiferromagnetic coupling was found for the system. With the thickness of Si layer tSi increasing, the perpendicular anisotropy constant Ku, and the saturation magnetization Ms decreased rapidly. It was assumed that Co2Si and Tb had been formed in the interfacial zone between TbCo and Si layers due to the interlayer diffusion. The decreasing of Ms is attributed to the decreasing of the effective thickness of magnetic layer.

  12. Synthesis and properties of LnXBe (Ln=lanthanides, X=Si or Ge)

    NASA Astrophysics Data System (ADS)

    Ohnishi, T.; Takahashi, Y.; Mizusaki, S.; Samata, H.; Noro, Y.; Nagata, Y.

    2011-04-01

    The crystallographic and magnetic properties of LnXBe (Ln = lanthanides; X = Si or Ge) were investigated. All the samples have a hexagonal structure of space group P63/mmc. LnSiBe (Ln = Pr, Nd, Sm, Eu, Gd, Tb, Er) and LnGeBe (Ln = Pr, Nd, Sm, Gd, Tb, Dy, Ho) are ferromagnetic (Tc of 6-70 K), whereas LnSiBe (Ln = Dy, Ho) are antiferromagnetic and LnSiBe (Ln = La, Lu) and LnGeBe (Ln = La, Eu, Er, Lu) are paramagnetic. Possible existence of superconductivity was observed for paramagnetic LaSiBe.

  13. Active Case Finding of Tuberculosis (TB) in an Emergency Room in a Region with High Prevalence of TB in Brazil

    PubMed Central

    Silva, Denise Rossato; Müller, Alice Mânica; Tomasini, Karina da Silva; Dalcin, Paulo de Tarso Roth; Golub, Jonathan E.; Conde, Marcus Barreto

    2014-01-01

    Setting Public hospital emergency room (ER) in Porto Alegre, Brazil, a setting with high prevalence of tuberculosis (TB) and human immunodeficiency virus (HIV) infection. Objective To determine the prevalence of PTB, using a symptom based active case finding (ACF) strategy in the ER of a public hospital in an area with high prevalence of TB and HIV, as well as variables associated with pulmonary TB diagnosis. Methods Cross sectional study. All patients ?18 years seeking care at the ER were screened for respiratory symptoms and those with cough ?2 weeks were invited to provide a chest radiograph and two unsupervised samples of sputum for acid-fast bacilli smear and culture. Results Among 31,267 admissions, 6,273 (20.1%) reported respiratory symptoms; 197 reported cough ?2 weeks, of which pulmonary TB was diagnosed in 30. In multivariate analysis, the variables associated with a pulmonary tuberculosis diagnosis were: age (OR 0.94, 95% CI: 0.92–0.97; p<0.0001), sputum production (OR 0.18, 95% CI 0.06–0.56; p?=?0.003), and radiographic findings typical of TB (OR 12.11, 95% CI 4.45–32.93; p<0.0001). Conclusions This study identified a high prevalence of pulmonary TB among patients who sought care at the emergency department of a tertiary hospital, emphasizing the importance of regular screening of all comers for active TB in this setting. PMID:25211158

  14. Effect of Dy/Nd double layer on coercivity in Nd-Fe-B thin films

    SciTech Connect

    Koike, K., E-mail: kkoike@yz.yamagata-u.ac.jp; Umezawa, J.; Ishikawa, H.; Ogawa, D.; Mizuno, Y.; Kato, H. [Department of Applied Mathematics and Physics, Yamagata University, Yonezawa 992-8510 (Japan); Miyazaki, T.; Ando, Y. [Department of Applied Physics, Tohoku University, Sendai, 980-8579 (Japan)

    2014-05-07

    The Nd-Fe-B (t{sub NFB}?=?30?nm)/[Dy (t{sub Dy} nm)/Nd (t{sub Nd} nm)] (t{sub Dy/Nd}?=?20?nm) (thickness t{sub Dy}?=?0–10?nm) thin films were deposited on Al{sub 2}O{sub 3}(0001) substrate and subsequently in-situ annealed at 470?°C. As-deposited Nd-Fe-B thin films with a highly perpendicular orientation of c-axis were deposited by introducing bcc-Mo(111) single crystal buffer layer. After post-annealing, the grain size of the Nd-Fe-B/Dy/Nd thin films with the t{sub Dy}?=?10?nm and t{sub Nd}?=?10?nm becomes large due to the Dy and the Nd atoms thermal diffusion, while DyFe{sub 2} and Dy oxide compounds are formed in Nd-Fe-B layers, which is confirmed by means of a combination of atomic force microscopy observation and X-ray diffraction measurement. The H{sub c} of Nd-Fe-B/Dy/Nd thin films with the t{sub Dy}?=?10?nm and t{sub Nd}?=?10?nm was approximately the same value of the Nd-Fe-B thin films without Dy/Nd double layer annealed at 470?°C. On the other hand, H{sub c} is enhanced to be about 22.1?kOe in the annealed Nd-Fe-B/Dy/Nd films with the t{sub Dy}?=?0.8?nm and t{sub Nd}?=?19.2?nm.

  15. Specific heat of Gd?Co?.

    PubMed

    Seixas, T M; Salgueiro da Silva, M A; de Lima, O F; Lopez, J; Braun, H F; Eska, G

    2010-04-01

    The specific heat (C(T)) of Gd?Co? was measured in the temperature range 2-300 K and its magnetic contribution (C(m)(T)) was determined using a new method that fits the electronic specific heat coefficient (?) and the Debye temperature (?(D)) by constraining the resulting magnetic entropy (S(m)(T)) to saturate at temperatures far above the Curie temperature (T(C)). C(m)(T) exhibits a low-temperature bump originating from thermal excitation of gapped spin waves, which is responsible for pronounced peaks, at ?35 K, in both C(m)/T and the temperature derivative of the magnetic contribution to electrical resistivity (d?(m)/dT). Apart from in the vicinity of T(C), an excellent global correlation was found between C(m)/T and d?(m)/dT. Our results provide strong support for the consistency of the new method proposed for the determination of C(m)(T) and rule out any major role of short-range order on Gd moments or d-electron spin fluctuation effects in the paramagnetic phase. A comparative analysis with other methods used in similar compounds points to the need for a better evaluation of C(m)(T) in such compounds, especially in the magnetically ordered phase, where a deficient evaluation of C(m)/T has a larger impact on the S(m)(T) curve. PMID:21389520

  16. Crystal chemistry and thermoelectric properties of Gd2Te3

    NASA Astrophysics Data System (ADS)

    Swinnea, J. S.; Steinfink, H.; Danielson, L. R.

    The physical characteristic and properties of Gd2Te3 are presented: M(sub r) = 697.30, orthorhombic, Pnma, a = 12.009(9), b = 4.3012 (6), c = 11.818(2) A, V = 610.4(6) A(sup 3), Z = 4, D sub x = 7.57 gm/cubic cm, MoK(sub alpha), lambda = 0.71069 A, mu = 357/cm, F(000) = 1136, room temperature, R = 0.033,822 observed reflections. The redetermination confirms that Gd2Te3 is isostructural with Sb2S3 (stibnite). The reported solid solution series Gd2Te3-Gd3Te4 does not exist. Gd-Te bond lengths vary from 3.104(1) to 3.240(3) A and Gd is in seven fold co-ordination. Gd2Te3 has a power factor S(sup 2)/rho = -.000006V(sup 2 degrees)/C(sup 2)/omega/cm at 1000 C. It is not suitable as a high temperature thermoelectric material because it decomposes to GdTe which is metallic.

  17. Raman spectra of crystalline and molten GdCl3

    Microsoft Academic Search

    I. D. Zakir'yanova; A. B. Salyulev

    2010-01-01

    The Raman spectra of crystalline (over a wide temperature range) and molten GdCl3 are mea- sured. The hexagonal structure C 2 6h (UClC26h3 type) of crystalline GdCl3 is found to change weakly over the entire temperature range under study. The temperature dependences of the characteristic frequencies change in the premelting range.

  18. Effect of Gd3+ on the colloidal stability of liposomes

    NASA Astrophysics Data System (ADS)

    Sabín, Juan; Prieto, Gerardo; Sennato, Simona; Ruso, Juan M.; Angelini, Roberta; Bordi, Federico; Sarmiento, Félix

    2006-09-01

    Lanthanide ions such as La3+ and Gd3+ are well known to have large effects on the structure of phospholipid membranes. Unilamellar vesicles of dipalmitoylphosphatidylcholine (DPPC) were prepared by sonication method and confirmed by transmission electron microscopy. The effects of concentration of gadolinium ions Gd3+ on DPPC unilamellar vesicles in aqueous media were studied by different techniques. As physical techniques, photon correlation spectroscopy, electrophoretic mobility, and differential scanning calorimetry were used. The theoretical predictions of the colloidal stability of liposomes were followed using the Derjaguin-Landau-Verwey-Overbeek theory. Changes in the size of liposomes and high polydispersities values were observed as Gd3+ concentration increases, suggesting that this cation induces the aggregation of vesicles. Electrophoretic mobility measurements on unilamellar vesicles as a function of Gd3+ ion concentration show that the vesicles adsorb Gd3+ ions. Above Gd3+ concentrations of 0.1moldm-3 , the ? potential and light scattering measurements indicate the beginning of aggregation process. For comparison with similar phospholipids, the zeta potential of phosphatidylcholine interacting with Gd3+ was measured, showing an analogous behavior. Differential scanning calorimetry has been used to determine the effect of Gd3+ on the transition temperature (Tc) and on the enthalpy (?Hc) associated with the process.

  19. Electronic transitions in GdN band structure

    SciTech Connect

    Vidyasagar, R., E-mail: drsagar@sapphire.kobe-u.ac.jp; Kita, T. [Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Kobe 657-8501 (Japan); Sakurai, T. [Centre for Support to Research and Education Activities, Kobe University, 1-1 Rokkodai, Kobe 657-8501 (Japan); Ohta, H. [Molecular Photoscience Research Center and Graduate School of Science, Kobe University, 1-1 Rokkodai, Kobe 657-8501 (Japan)

    2014-05-28

    Using the near-infrared (NIR) absorbance spectroscopy, electronic transitions and spin polarization of the GdN epitaxial film have been investigated; and the GdN epitaxial film was grown by a reactive rf sputtering technique. The GdN film exhibited three broad bands in the NIR frequency regimes; and those bands are attributable primarily to the minority and majority spin transitions at the X-point and an indirect transition along the ?-X symmetric direction of GdN Brillouin zone. We experimentally observe a pronounced red-shift of the indirect band gap when cooling down below the Curie temperature which is ascribed to the orbital-dependent coulomb interactions of Gd-5dxy electrons, which tend to push-up the N-2p bands. On the other hand, we have evaluated the spin polarization of 0.17 (±0.005), which indicates that the GdN epitaxial film has almost 100% spin-polarized carriers. Furthermore, the experimental result of GdN electronic transitions are consistent with the previous reports and are thus well-reproduced. The Arrott plots evidenced that the Curie temperature of GdN film is 36?K and the large spin moment is explained by the nitrogen vacancies and the intra-atomic exchange interaction.

  20. Crystal field states of Tb3 + in the pyrochlore spin liquid Tb2Ti2O7 from neutron spectroscopy

    NASA Astrophysics Data System (ADS)

    Princep, A. J.; Walker, H. C.; Adroja, D. T.; Prabhakaran, D.; Boothroyd, A. T.

    2015-06-01

    We report time-of-flight neutron scattering measurements of the magnetic spectrum of Tb3 + in Tb2Ti2O7 . The data, which extend up to 120 meV and have calibrated intensity, enable us to consolidate and extend previous studies of the single-ion crystal field spectrum. We successfully refine a model for the crystal field potential in Tb2Ti2O7 without relying on data from other rare-earth titanate pyrochlores, and we confirm that the ground state is a non-Kramers doublet with predominantly |±4 > components. We compare the model critically with earlier models.

  1. Caecal perforation from TB and the Law of Laplace.

    PubMed

    Khan, Amad N; Khalid, Salema; Chaudhry, Mohammad Naushad; Ho, Cherrie

    2015-01-01

    A 43-year-old man presented to the hospital with haemoptysis. When worked up, his history and examination were highly suggestive of pulmonary tuberculosis (TB). He subsequently developed a massive upper gastrointestinal bleed and underwent an emergency laparotomy, which revealed a massively dilated caecum measuring ?20 cm in diameter. The caecum had perforated due to acute decompensation of intestinal TB. Though common in developing countries, TB is rare in the UK, especially the intestinal kind. The most striking feature of this case is, however, the size of the caecal distension caused by the tubercular inflammation and subsequent perforation-something unheard of in the literature. This massive caecal distention would be explained by the Law of Laplace. In conclusion, massive distension and caecal perforation are possible consequences of intestinal TB, especially in the 48-72 h immediately after starting anti-tubercular therapy. PMID:25972412

  2. 46 CFR 32.75-1 - Application-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...EQUIPMENT, MACHINERY, AND HULL REQUIREMENTS Hull Requirements for Wood Hull Tank Vessels Constructed Prior to November 10, 1936 § 32.75-1 Application—TB/ALL. All wood hull tank vessels, the construction or conversion of which was...

  3. Disparities in HIV/AIDS, Viral Hepatitis, STDs, and TB

    MedlinePLUS

    ... this page: About CDC.gov . Disparities in HIV/AIDS, Viral Hepatitis, STDs, and TB Health Disparities Social ... Islanders LGBT Populations/MSM MMWR Publications HIV and AIDS Viral Hepatitis STDs Tuberculosis Training and Networking Resources ...

  4. Observations of nanocrystals in thin TbFeCo films

    SciTech Connect

    Li, Z.G.; Smith, D.J. (Center for Solid State Science, Arizona State University, Tempe, Arizona 85287 (US)); Sickafus, K. (Department 68V/061-1, General Products Division, IBM Corporation, Tucson, Arizona 85744)

    1989-08-28

    Observations of thin films of amorphous TbFeCo by electron microscopy with a resolution limit of better than 0.2 nm invariably reveal the presence of very fine microcrystals (sizes {similar to}2--5 nm). Bright field imaging, in both plan view and in cross section, indicates that these nanocrystals have the crystal structure of {alpha}-Fe or Co. In contrast, crystals of Tb metal (or Tb oxides) have not been observed. Similar observations of FeCo thin films, prepared under identical experimental conditions, reveal much larger crystals (typically 10--50 nm). It is concluded that the presence of the rare earth element Tb is crucial to the microstructure displayed by this kind of material.

  5. Acoustic Faraday effect in Tb3Ga5O12

    Microsoft Academic Search

    A. Sytcheva; U. Löw; S. Yasin; J. Wosnitza; S. Zherlitsyn; P. Thalmeier; T. Goto; P. Wyder; B. Lüthi

    2010-01-01

    The transverse acoustic wave propagating along the [100] axis of the cubic Tb3Ga5O12 (acoustic c44 mode) is doubly degenerate. A magnetic field applied in the direction of propagation lifts this degeneracy and leads to the rotation of the polarization vector---the magnetoacoustic Faraday rotation. Here, we report on the observation and analysis of the magnetoacoustic Faraday effect in Tb3Ga5O12 in static

  6. Low angle polarized neutron diffraction from Tb/Fe multilayers

    NASA Astrophysics Data System (ADS)

    Dufour, C.; Vergnat, M.; Cherifi, K.; Marchal, G.; Mangin, Ph.; Vettier, C.

    1992-06-01

    Low angle polarized neutron scattering experiments have been performed on a Tb(61 Å)/Fe(55Å) multilayer. The evolution of the intensities ( I+ and I-) of the first peak shows that the average magnetizations of Tb and Fe are in the applied field direction. The intensities of the second and the third peaks indicate that there is an interface effect which is going along with the terbium magnetization. It is presumably the result of the antiferromagnetic coupling between iron and terbium.

  7. Completeness of pediatric TB reporting in New York City.

    PubMed Central

    San Gabriel, Pablo; Saiman, Lisa; Kaye, Katherine; Silin, Muriel; Onorato, Ida; Schulte, Joann

    2003-01-01

    OBJECTIVE: Accurate surveillance of tuberculosis (TB) in children is critical because such cases represent recent transmission, but surveillance is difficult as only 10% to 50% of cases are culture-confirmed. Hospital-based sources were used to develop alternative surveillance to assess completeness of reporting for pediatric TB in northern Manhattan and Harlem from 1993 through 1995. METHODS: Alternative surveillance sources included ICD-9-CM hospital discharge codes for active TB and gastric aspirate reports. Cases identified by alternative surveillance were compared with cases previously reported to the New York City Department of Health (NYC DOH). RESULTS: Alternative surveillance detected 25 cases of possible pediatric TB, of which four (16%) had never been reported to the NYC DOH and three (12%) had been reported as suspect cases, but had not fulfilled the criteria for a reportable case of pediatric TB. Of these seven newly counted cases, three were detected by ICD-9-CM codes, three by a gastric aspirate log book, and one by both. In contrast, 13 other cases had been reported to the NYC DOH, but were undetected by our alternative surveillance; eight of these could be verified with available medical records. Thus, the demographic and clinical characteristics of the 25 detected and the eight undetected cases with available medical records were evaluated in this study. CONCLUSION: Alternative surveillance proved effective, was complementary to the NYC DOH surveillance efforts, and increased the number of pediatric TB cases identified during the study period by 21%. PMID:12690068

  8. Ground State Magnetic Properties of Odd Neutron DY Isotopes

    NASA Astrophysics Data System (ADS)

    Yakut, Hakan; Tabar, Emre; Kuliev, Ali Akbar; Zenginerler, Zemine; Kaplan, Pinar

    2013-10-01

    Using the quasiparticle phonon nuclear model (QPNM) and taking into account the spin-spin interaction, the effects of the spin polarization on spin gyromagnetic factors (gs) as well as the intrinsic magnetic moments (gK) of the deformed odd neutron 155-165Dy isotopes were studied. The calculated values of gs and gK are in fair agreement with the experiment as well as with other microscopic calculations. Our calculations indicated that because of the core polarization, the gs factors of the nucleons in the nucleus reduce noticeably from its free nucleon value and the spin-spin interactions play an important role in the explanation of the quenching of the gs factors. A very good reproduction of the phenomenological quenching of gs factor from its free values (gs eff = 0.6-0.7gs free) is obtained for 155-165Dy.

  9. Magnetoresistance anomaly in DyFeCo thin films

    SciTech Connect

    Wu, J. C.; Wu, C. S.; Wu, Te-ho; Chen, Bing-Mau; Shieh, Han-Ping D.

    2001-06-01

    Microstructured rare-earth{endash}transition-metal DyFeCo films have been investigated using magnetoresistance and extraordinary Hall-effect measurements. The Hall loops reveal variation of coercive fields depending on the linewidth and the composition of the films. The magnetoresistance curves, with changes up to as high as 1.3%, show positive/negative magnetoresistance peaks centered on the coercive fields depending on the linewidth of the films only. The variation of the coercivity can be attributed to the magnetic moment canting between the Dy and FeCo subcomponents and the existence of the diverged magnetization on the edges, and the anomalous magnetoresistance peaks observed are discussed with the existing theories. {copyright} 2001 American Institute of Physics.

  10. Basidiomycete DyPs: Genomic diversity, structural-functional aspects, reaction mechanism and environmental significance.

    PubMed

    Linde, Dolores; Ruiz-Dueñas, Francisco J; Fernández-Fueyo, Elena; Guallar, Victor; Hammel, Kenneth E; Pogni, Rebecca; Martínez, Angel T

    2015-05-15

    The first enzyme with dye-decolorizing peroxidase (DyP) activity was described in 1999 from an arthroconidial culture of the fungus Bjerkandera adusta. However, the first DyP sequence had been deposited three years before, as a peroxidase gene from a culture of an unidentified fungus of the family Polyporaceae (probably Irpex lacteus). Since the first description, fewer than ten basidiomycete DyPs have been purified and characterized, but a large number of sequences are available from genomes. DyPs share a general fold and heme location with chlorite dismutases and other DyP-type related proteins (such as Escherichia coli EfeB), forming the CDE superfamily. Taking into account the lack of an evolutionary relationship with the catalase-peroxidase superfamily, the observed heme pocket similarities must be considered as a convergent type of evolution to provide similar reactivity to the enzyme cofactor. Studies on the Auricularia auricula-judae DyP showed that high-turnover oxidation of anthraquinone type and other DyP substrates occurs via long-range electron transfer from an exposed tryptophan (Trp377, conserved in most basidiomycete DyPs), whose catalytic radical was identified in the H2O2-activated enzyme. The existence of accessory oxidation sites in DyP is suggested by the residual activity observed after site-directed mutagenesis of the above tryptophan. DyP degradation of substituted anthraquinone dyes (such as Reactive Blue 5) most probably proceeds via typical one-electron peroxidase oxidations and product breakdown without a DyP-catalyzed hydrolase reaction. Although various DyPs are able to break down phenolic lignin model dimers, and basidiomycete DyPs also present marginal activity on nonphenolic dimers, a significant contribution to lignin degradation is unlikely because of the low activity on high redox-potential substrates. PMID:25637654

  11. Carbide clusterfullerene Gd2C2@C92 vs dimetallofullerene Gd2@C94: a quantum chemical survey.

    PubMed

    Guo, Yi-Jun; Yang, Tao; Nagase, Shigeru; Zhao, Xiang

    2014-02-17

    The geometric, electronic structure, and thermodynamic stability of Gd2C94 species, including dimetallofullerenes Gd2@C94 and carbide clusterfullerenes Gd2C2@C92, have been systematically investigated by a density functional theory approach combined with statistical mechanics calculations. Although the Gd2@C2(153480)-C94 is determined to possess the lowest energy, its molar fraction at the temperature region of fullerene formation is extremely low if the temperature effect is taken into consideration. Meanwhile, three C92-based carbide clusterfullerene species, Gd2C2@D3(126408)-C92, Gd2C2@C1(126390)-C92, and Gd2C2@C2(126387)-C92, with some higher energy are exposed to possess considerable thermodynamic stabilities within a related temperature interval, suggesting that carbide clusterfullerenes rather than dimetallofullerenes could be isolated experimentally. Although one isomer, Gd2C2@D3(126408)-C92, has been indeed obtained experimentally, a novel structure, Gd2C2@C1(126390)-C92, behaving as the most abundant isomer at more elevated temperatures with the largest SOMO-LUMO gap, is predicted for the first time to be another proper isomer isolated in the experiment. Moreover, in order to further analyze the interaction between gadolinium atoms and carbon atoms in either a carbide cluster or a fullerene cage, frontier molecular orbital, natural bond orbital, and Mayer bond order analyses have been employed, and the results show that the covalent interaction cannot be neglected. The IR spectra of Gd2C2@C92 have been simulated to provide some valuable guidance for future experiments. PMID:24495172

  12. Shell model Monte Carlo calculations for Dy-170

    E-print Network

    D. J. Dean; S. E. Koonin; G. H. Lang; P. B. Radha; W. E. Ormand

    1993-09-28

    We present the first auxiliary field Monte Carlo calculations for a rare earth nucleus, Dy-170. A pairing plus quadrupole Hamiltonian is used to demonstrate the physical properties that can be studied in this region. We calculate various static observables for both uncranked and cranked systems and show how the shape distribution evolves with temperature. We also introduce a discretization of the path integral that allows a more efficient Monte Carlo sampling.

  13. Photographic copy of plan of new Dy horizontal station and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photographic copy of plan of new Dy horizontal station and accumulator additions to Test Stand "D," also showing existing Dd test station. JPL drawing by VTN Consolidated, Inc. Engineers, Architects, Planners, 2301 Campus Drive, Irvine, California 92664: "Jet Propulsion Laboratory-Edwards Test Station, Motive Steam Supply & Ejector Pumping System: Plan - Test Stand "D," sheet M-3 (JPL sheet number E24/33), 21 December 1976 - Jet Propulsion Laboratory Edwards Facility, Test Stand D, Edwards Air Force Base, Boron, Kern County, CA

  14. Optical absorption and fluorescence properties of Dy3+: SFB glasses

    NASA Astrophysics Data System (ADS)

    Maheswari, D. Uma; Kumar, J. Suresh; Sasikala, T.; Mohan Babu, A.; Pavani, K.; Jang, Kiwan; Rama Moorthy, L.

    2009-07-01

    This paper presents the preparation and spectroscopic characterization of Dy3+-doped sodium fluoroborate (SFB) glasses of the type (50-x) B2O3 + 25 Na2O + 10 CaF2 + 10 AlF3 + 5 LaF3 + x DyF3 (x = 0.01, 0.1, 0.5,1.0, 2.0 and 4.0 mol%). By measuring the area under absorption bands, the experimental oscillator strengths are determined. The Judd-Ofelt (J-O) intensity parameters ?? (? = 2, 4, 6) are evaluated by the least square fit method. These phenomenological parameters are used to predict luminescence properties of the lanthanide ions in SFB glasses. Photoluminescence spectra and lifetimes of 4F9/2 level of Dy3+ ions in these glasses have been measured by exciting with 348 nm line of xenon flash lamp. The measured decay curves exhibit single exponential at lower concentrations of 0.01, 0.1, 0.5 and 1.0 mol% and non-exponential at higher concentrations of 2.0 and 4.0 mol%. The predicted ?R and (?R values of 4F9/2 transition are compared with the experimentally measured values. From the magnitude of stimulated emission cross sections (?e), branching ratios (?m), multiphonon relaxation rates (WMP), the most potential laser transitions are identified and the utility of these glasses as laser active material is discussed.

  15. Fracture Toughness Properties of Gd123 Superconducting Bulks

    NASA Astrophysics Data System (ADS)

    Fujimoto, H.; Murakami, A.

    Fracture toughness properties of melt growth GdBa2Cu3Ox (Gd123) large single domain superconducting bulks with Ag2O of 10 wt% and Pt of 0.5 wt%; 45 mm in diameter and 25 mm in thickness with low void density were evaluated at 77 K through flexural tests of specimens cut from the bulks, and compared to those of a conventional Gd123 with voids. The densified Gd123 bulks were prepared with a seeding and temperature gradient method; first melt processed in oxygen, then crystal growth in air; two-step regulated atmosphere heat treatment. The plane strain fracture toughness, KIC was obtained by the three point flexure test of the specimens with through precrack, referring to the single edge pre-cracked beam (SEPB) method, according to the JIS-R-1607, Testing Methods for Fracture Toughness of High Performance Ceramics. The results show that the fracture toughness of the densified Gd123 bulk with low void density was higher than that of the standard Gd123 bulk with voids, as well as the flexural strength previously reported. We also compared the fracture toughness of as-grown bulks with that of annealed bulks. The relation between the microstructure and the fracture toughness of the Gd123 bulk was clearly shown.

  16. Engineering anti-GD2 monoclonal antibodies for cancer immunotherapy.

    PubMed

    Ahmed, Mahiuddin; Cheung, Nai-Kong V

    2014-01-21

    Ganglioside GD2 is highly expressed on neuroectoderm-derived tumors and sarcomas, including neuroblastoma, retinoblastoma, melanoma, small cell lung cancer, brain tumors, osteosarcoma, rhabdomyosarcoma, Ewing's sarcoma in children and adolescents, as well as liposarcoma, fibrosarcoma, leiomyosarcoma and other soft tissue sarcomas in adults. Since GD2 expression in normal tissues is restricted to the brain, which is inaccessible to circulating antibodies, and in selected peripheral nerves and melanocytes, it was deemed a suitable target for systemic tumor immunotherapy. Anti-GD2 antibodies have been actively tested in clinical trials for neuroblastoma for over the past two decades, with proven safety and efficacy. The main limitations have been acute pain toxicity associated with GD2 expression on peripheral nerve fibers and the inability of antibodies to treat bulky tumor. Several strategies have been developed to reduce pain toxicity, including bypassing complement activation, using blocking antibodies, or targeting of O-acetyl-GD2 derivative that is not expressed on peripheral nerves. To enhance anti-tumor efficacy, anti-GD2 monoclonal antibodies and fragments have been engineered into immunocytokines, immunotoxins, antibody drug conjugates, radiolabeled antibodies, targeted nanoparticles, T-cell engaging bispecific antibodies, and chimeric antigen receptors. The challenges of these approaches will be reviewed to build a perspective for next generation anti-GD2 therapeutics in cancer therapy. PMID:24295643

  17. Enneanuclear [Ni6Ln3] Cages: [Ln(III)3] Triangles Capping [Ni(II)6] Trigonal Prisms Including a [Ni6Dy3] Single-Molecule Magnet.

    PubMed

    Canaj, Angelos B; Tzimopoulos, Demetrios I; Siczek, Milosz; Lis, Tadeusz; Inglis, Ross; Milios, Constantinos J

    2015-07-20

    The use of (2-(?-naphthalideneamino)-2-hydroxymethyl-1-propanol) ligand, H3L, in Ni/Ln chemistry has led to the isolation of three new isostructural [Ni(II)6Ln(III)3] metallic cages. More specifically, the reaction of Ni(ClO4)2·6H2O, the corresponding lanthanide nitrate salt, and H3L in MeCN, under solvothermal conditions in the presence of NEt3, led to the isolation of three complexes with the formulas [Ni6Gd3(OH)6(HL)6(NO3)3]·5.75MeCN·2Et2O·1.5H2O (1·5.75MeCN·2Et2O·1.5H2O), [Ni6Dy3(OH)6(HL)6(NO3)3]·2MeCN·2.7Et2O·2.4H2O (2·2MeCN·2.7Et2O·2.4H2O), and [Ni6Er3(OH)6(HL)6(NO3)3]·5.75MeCN·2Et2O·1.5H2O (3·5.75MeCN·2Et2O·1.5H2O). The structure of all three clusters describes a [Ln(III)3] triangle capping a [Ni(II)6] trigonal prism. Direct current magnetic susceptibility studies in the 5-300 K range for complexes 1-3 reveal the different nature of the magnetic interactions within the clusters: dominant antiferromagnetic exchange interactions for the Dy(III) and Er(III) analogues and dominant ferromagnetic interactions for the Gd(III) example. Alternating current magnetic susceptibility measurements under zero external dc field displayed fully formed temperature- and frequency-dependent out-of-phase peaks for the [Ni(II)6Dy(III)3] analogue, establishing its single molecule magnetism behavior with Ueff = 24 K. PMID:26135204

  18. A salen-type Dy4 single-molecule magnet with an enhanced energy barrier and its analogues.

    PubMed

    Luan, Fang; Yan, Pengfei; Zhu, Jing; Liu, Tianqi; Zou, Xiaoyan; Li, Guangming

    2015-03-01

    Four isomorphic tetranuclear lanthanide complexes, namely [Ln4(L)2(HL)2(NO3)2(OH)2](NO3)2·4H2O (Ln = Dy (1); Tb (2); Ho (3); Er (4)), constructed using hexadentate salen-type ligand N,N'-bis(3-methoxy-salicylidene)cyclohexane-1,2-diamine, have been isolated. X-ray crystallographic analysis reveals that all of the complexes 1-4 are of discrete tetranuclear structure with a unique {Ln4O8} core in which four lanthanide ions are coplanar in a rhombic frame. There are two crystallographically unequivalent lanthanide ions, that is the Ln1(III) ion which is nine-coordinated in a monocapped square-antiprismatic geometry of the C(4v) point group and the Ln2(III) ion which is eight-coordinated in a distorted bicapped trigonal-prismatic geometry of the C(2v) point group. Magnetic analysis reveals that complex 1 exhibits two slow magnetic relaxations with the highest energy barrier among the reported tetranuclear salen-type dysprosium SMMs. This further extends the available SMMs of salen-type lanthanide complexes. PMID:25619145

  19. Anomalous low-temperature magnetic behaviour in DyRu2Si2 and DyRu2Ge2

    NASA Astrophysics Data System (ADS)

    Bouvier, M.; Fraga, G. L. F.; Garnier, A.; Gignoux, D.; Schmitt, D.; Shigeoka, T.

    1996-03-01

    The body-centred tetragonal compounds DyRu2Si2 and DyRu2Ge2 order within a collinear modulated magnetic structure at TN = 29 and 22 K, respectively. Below ~ 5 K, both compounds present a low-field low-temperature magnetic state which exhibits several non-conventional features. The most spectacular one is a double-peak structure in the temperature dependence of the specific heat, associated with a giant variation of the magnetic entropy. Other anomalous characteristics include an unexpected change of behaviour in the magnetization processes and an unusual variation of the resistivity in this temperature range. The nature of this low-temperature phase is a puzzle.

  20. Polarization enhancement and ferroelectric switching enabled by interacting magnetic structures in DyMnO3 thin films

    PubMed Central

    Lu, Chengliang; Dong, Shuai; Xia, Zhengcai; Luo, Hui; Yan, Zhibo; Wang, Haowen; Tian, Zhaoming; Yuan, Songliu; Wu, Tao; Liu, Junming

    2013-01-01

    The mutual controls of ferroelectricity and magnetism are stepping towards practical applications proposed for quite a few promising devices in which multiferroic thin films are involved. Although ferroelectricity stemming from specific spiral spin ordering has been reported in highly distorted bulk perovskite manganites, the existence of magnetically induced ferroelectricity in the corresponding thin films remains an unresolved issue, which unfortunately halts this step. In this work, we report magnetically induced electric polarization and its remarkable response to magnetic field (an enhancement of ~800% upon a field of 2 Tesla at 2?K) in DyMnO3 thin films grown on Nb-SrTiO3 substrates. Accompanying with the large polarization enhancement, the ferroelectric coercivity corresponding to the magnetic chirality switching field is significantly increased. A picture based on coupled multicomponent magnetic structures is proposed to understand these features. Moreover, different magnetic anisotropy related to strain-suppressed GdFeO3-type distortion and Jahn-Teller effect is identified in the films. PMID:24291803

  1. Stellar neutron capture cross sections of the Gd isotopes

    NASA Astrophysics Data System (ADS)

    Wisshak, K.; Voss, F.; Käppeler, F.; Guber, K.; Kazakov, L.; Kornilov, N.; Uhl, M.; Reffo, G.

    1995-11-01

    The neutron capture cross sections of 152Gd, 154Gd, 155Gd, 156Gd, 157Gd, and 158Gd were measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p,n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? Barium Fluoride Detector, which was improved by replacing crystals with high ? background and by introducing a pierced crystal at zero degrees with respect to the beam axis. These changes resulted in a significantly increased efficiency for capture events. The main experimental problem was that the samples of the two s isotopes 152Gd and 154Gd showed only relatively low enrichment. Nevertheless, the spectroscopic quality of the BaF2 detector allowed evaluation of the corresponding corrections for isotopic impurities reliably. The cross section ratios could be determined with an overall uncertainty of typically 1%, an improvement by factors of five to ten compared to existing data. Severe discrepancies were found with respect to previous results. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT=10 keV and 100 keV. The new stellar cross sections were used for an updated analysis of the s-process reaction flow in the mass region between samarium and gadolinium, which is characterized by branchings at 151Sm, 154Eu, and 155Eu. With the classical approach, the s-process temperature could be constrained corresponding to a range of thermal energies between kT=28 and 33 keV. The 152Gd production in low mass stars was found to depend strongly on the neutron freeze-out at the end of the helium shell burning episodes.

  2. Stellar neutron capture cross sections of the Gd isotopes.

    NASA Astrophysics Data System (ADS)

    Wisshak, K.; Voss, F.; Käppeler, F.; Guber, K.; Kazakov, L.; Kornilov, N.; Uhl, M.; Reffo, G.

    1995-05-01

    The neutron capture cross sections of 152Gd, 154Gd, 155Gd, 156Gd, 157Gd, and 158Gd were measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p, n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? Barium Fluoride Detector The main experimental problem was that the samples of the two s-only isotopes 152Gd and 154Gd showed only relatively low enrichment, but the spectroscopic quality of the BaF2 detector allowed to determine the resulting corrections for isotopic impurities reliably. The cross section ratios could be determined with an overall uncertainty of typically 1%, an improvement by factors of five to ten compared to existing data. Severe discrepancies were found with respect to previous results. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT = 10 keV and 100 keV. The new stellar cross sections were used for an updated analysis of the s-process reaction flow in the mass region between samarium and gadolinium, which is characterized by branchings at 151Sm, 154Eu, and 155Eu. With the classical approach, the s-process temperature could be constrained corresponding to a range of thermal energies between kT - 28 keV and 33 keV. The 152Gd production in low mass stars was found to depend strongly on the neutron freeze-out at the end of the helium shell burning episodes.

  3. Properties of alginate fiber spun-dyed with fluorescent pigment dispersion.

    PubMed

    Wang, Ping; Tawiah, Benjamin; Tian, Anli; Wang, Chunxia; Zhang, Liping; Fu, Shaohai

    2015-03-15

    Spun-dyed alginate fiber was prepared by the spun-dyeing method with the mixture of fluorescent pigment dispersion and sodium alginate fiber spinning solution, and its properties were characterized by SEM, TGA, DSC, and XRD. The results indicate that fluorescent pigment dispersion prepared with esterified poly (styrene-alt maleic acid) had excellent compatibility with sodium alginate fiber spinning solution, and small amount of fluorescent pigment could reduce the viscosity of spun-dyed spinning solutions. SEM photo of spun-dyed alginate fiber indicated that fewer pigment particles deposited on its surface. TGA, DSC, and XRD results suggested that thermal properties and crystal phase of spun-dyed alginate fibers had slight changes compared to the original alginate fibers. The fluorescence intensity of spun-dyed alginate fiber reached its maximum when the content of fluorescent pigment was 4%. The spun-dyed alginate fiber showed excellent rubbing and washing fastness. PMID:25542119

  4. Study on the low-temperature properties of pyrochlores Gd2Hf2O7 and Gd2Zr2O7, using crystal-field theory

    Microsoft Academic Search

    Aksar Ali Biswas; Yatramohan Jana

    2011-01-01

    The geometrically frustrated pyrochlores Gd2Hf2O7 (GdH) and Gd2Zr2O7 (GdZ) are easy planar anisotropic systems in which considerable single-ion crystal-field anisotropies of D3d symmetry are found in the ground multiplet 8S7\\/2 due to admixture of higher Russell-Saunders terms. The 8S7\\/2 splits into 4 doublets with total CF splitting 9.9 K in GdH and 9.4 K in GdZ. The magnetic specific heat

  5. Magnetic resonance in multilayer Gd/Si/Co magnetic films

    SciTech Connect

    Patrin, G. S. [Russian Academy of Sciences, Kirenskii Institute of Physics, Siberian Division (Russian Federation)], E-mail: patrin@iph.krasn.ru; Vas'kovskii, V. O.; Svalov, A. V. [Ural State University (Russian Federation); Eremin, E. V.; Panova, M. A.; Vasil'ev, V. N. [Russian Academy of Sciences, Kirenskii Institute of Physics, Siberian Division (Russian Federation)

    2006-01-15

    The magnetic properties of multilayer Gd/Si/Co magnetic films are experimentally studied by electron magnetic resonance and analyzed theoretically. The introduction of a semiconductor silicon interlayer is found to substantially affect the magnetic interlayer coupling and the magnetic dynamics of the system. The interlayer coupling is shown to be ferromagnetic for the (Gd/Si){sub n} films and to be antiferromagnetic for the (Gd/Si/Co/Si){sub n} films. The temperature dependences of the exchange parameters and the gyromagnetic ratios are determined. Possible mechanisms responsible for the formation of the interlayer coupling are discussed.

  6. Hyperfine Interactions of Pm in Nd and Gd Hosts

    NASA Astrophysics Data System (ADS)

    Dogra, R.; Thakur, P.; Bhati, A. K.; Bedi, S. C.

    2001-11-01

    Time differential perturbed angular correlation measurements were carried out using short lived isomeric 5/2+ state in 147Pm to investigate the magnetic and electric hyperfine interactions in Nd and Gd hosts at different temperatures. At 10 K the magnetic hyperfine fields at 147Pm in Nd and Gd hosts are 361(42) kG and 256(30) kG, respectively, and are very low as compared to the free-ion value while the electric field gradients are of comparable order. The magnetic hyperfine field in Gd is constant with temperature. The results are interpreted in terms of singlet ground state of Pm ion.

  7. Structural determination of ceria zirconia nanosystem doped by Gd

    NASA Astrophysics Data System (ADS)

    Kolko, V. P.; Kriventsov, V. V.; Kochubey, D. I.; Zyuzin, D. A.; Moroz, E. M.; Sadykov, V. A.; Kosmambetova, G. R.; Strizhak, P. Y.

    2007-05-01

    The work is devoted to the structural study of doped Gd ceria-zirconia nanosystem by the EXAFS, WAXS (wide angle X-ray scattering) and XRD methods. A polymerized complex precursor method (Pechini route) was used for synthesis of ceria-zirconia doped by Gd. It was found by XRD analysis that samples of ceria-zirconia doped by Gd have a CeO2-reference structure (a cubic fluorite-like structure). However, analysis of the EXAFS and WAXS revealed the existence of two solid solutions with different content of zirconium cations, this implies heterogeneity on local level of structure.

  8. Ganglioside GD3 biosynthesis in normal and mutant mouse embryos

    Microsoft Academic Search

    Alexander M. Novikov; Thomas N. Seyfried

    1991-01-01

    CMP-sialic acid:GM3 sialyltransferase (GD3 synthase; EC 2.4.99.8) was characterized in a membrane-enriched preparation (P2 pellet) from mouse embryos at embryonic day 12 (E-12). Gangliosides GD3 and GM3 were the major radiolabeled products of the reaction. Optimum GD3 synthase activity was obtained atpH 6.0 using 0.1% detergent Triton CF-54. TheKm values for GM3 and CMP-sialic acid were 55 and 80 µM,

  9. Ganglioside GD3 biosynthesis in normal and mutant mouse embryos

    Microsoft Academic Search

    Alexander M. Novikov; Thomas N. Seyfried

    1991-01-01

    CMP-sialic acid:GM3 sialyltransferase (GD3 synthase; EC 2.4.99.8) was characterized in a membrane-enriched preparation (P2 pellet) from mouse embryos at embryonic day 12 (E-12). Gangliosides GD3 and GM3 were the major radiolabeled products of the\\u000a reaction. Optimum GD3 synthase activity was obtained atpH 6.0 using 0.1% detergent Triton CF-54. TheK\\u000a m values for GM3 and CMP-sialic acid were 55 and 80

  10. Phase equilibria in the Gd?Au system

    Microsoft Academic Search

    Adriana Saccone; Maria Luisa Fornasini; Daniele Macciò; Stefano Delfino

    1996-01-01

    The Gd?Au phase diagram was studied in the 0–100 at% Au composition range by differential thermal analysis (DTA), X-ray diffraction (XRD), optical and scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). Eight intermetallic compounds were identified and their melting behaviour was determined: Gd2Au (orthorhombic, oP12-Co2Si type, peritectic decomposition 935 °C), GdAu (L.T. form, orthorhombic, oC8-CrB type, and H.T. form,

  11. Bovine gd T-Cell Responses to the Intracellular Protozoan Parasite Theileria parva

    Microsoft Academic Search

    CLAUDIA A. DAUBENBERGER; EVANS L. N. TARACHA; LAIMA GAIDULIS; WILLIAM C. DAVIS; DECLAN J. MCKEEVER

    1999-01-01

    T cells bearing the gd antigen receptor (gd T cells) can constitute up to 50% of T cells in the peripheral blood and lymphoid organs of young cattle. We present data showing that gd T cells are involved in immune responses against Theileria parva. gd T cells isolated from peripheral blood mononuclear cells (PBMC) of T. parva-naive and -immune cattle

  12. Development of Gd-Enriched Alloys for Spent Nuclear Fuel Applications--Part 1: Preliminary Characterization

    E-print Network

    DuPont, John N.

    , Ni, Cr)3Gd intermetallic and the change in matrix structure from austenite to ferrite. A mass balance)3Gd intermetallic, and the amount of the (Fe, Ni, Cr)3Gd phase increased with increasing Gd baskets that sup- port spent fuel assemblies and serve the following three func- tions: (1) structural

  13. Thermoluminescence characteristics of MgSO 4:Dy,Mn phosphor

    Microsoft Academic Search

    Luo Daling; Zhang Chunxiang; Deng Zouping; Li Guozhen

    1999-01-01

    The MgSO4:Dy,Mn thermoluminescence (TL) phosphors have been prepared by co-doping with various concentrations of activators the Dy and Mn. The dose–responses to gamma-rays are studied by deconvolution of the TL glow curves. It is found that the TL sensitivity of the MgSO4:Dy,Mn phosphor is comparable to that of the phosphor LiF:Mg,Ti. Besides, there is only one main dosimetric peak at

  14. Risk factors for TB and HIV coinfection in Scotland, 2001 to 2010.

    PubMed

    McDonald, E; Smith-Palmer, A; Wallace, L A; Blatchford, O

    2015-01-01

    The number of patients with tuberculosis (TB) increased steadily in Scotland between 2005 and 2010. Human immunodeficiency virus (HIV) infection has been a contributory factor to increases in TB in a number of comparable industrialised countries. This study investigated the extent of, and risk factors for, TB and HIV coinfection in Scotland from 2001 to 2010. Patients with TB in the national TB database were linked to those in the national HIV database using probabilistic data linkage. Patient records were anonymised to maintain confidentiality. From 2001 to 2010, 106/4, 097 (2.6%, 95% CI: 2.1 to 3.1) TB patients matched with HIV patients, equating to a 10-year incidence of 2.1 cases per million population. Patients with both TB and HIV were more often born outside the United Kingdom,were of black African ethnicity, had refugee status and had extra-thoracic lymph node involvement or cryptic/disseminated TB disease. Individuals with TB and HIV coinfection were younger and symptomatic for a shorter time before their diagnosis of TB, compared with TB patients without HIV. TB and HIV coinfection was relatively uncommon in Scotland in the study period. Clinicians should recognise the potential for HIV infection among TB patients and the importance of offering an HIV test to all TB patients. PMID:25811644

  15. Evolution of magnetoelectric properties of Sc-diluted TbMnO3

    NASA Astrophysics Data System (ADS)

    Cuartero, V.; Blasco, J.; García, J.; Stankiewicz, J.; Subías, G.; Rodriguez-Velamazán, J. A.; Ritter, C.

    2013-05-01

    The magnetoelectric properties of the TbMn1-xScxO3 series have been studied at low temperatures by means of heat capacity, magnetic measurements and impedance spectroscopy. TbMnO3 exhibits as expected three transitions upon lowering the temperature corresponding to the magnetic ordering of the two sublattices (Mn and Tb) and the ferroelectric transition. Ferroelectricity disappears with Sc dilution for x > 0.1 because the non-collinear magnetic arrangement is destroyed. The dilution of Mn with a non-magnetic ion is also detrimental to the magnetic ordering of both Mn and Tb sublattices. The system evolves to a magnetic glassy state for the intermediate compositions. Formal TbScO3 shows Sc-deficiency and long range magnetic ordering of Tb3+ moments in the ab-plane brought by the direct interaction between Tb3+ ions. This ordering is different from the one found in TbMnO3 due to the lack of magnetic coupling between Tb- and Mn-sublattices. A small substitution of Sc by Mn in TbScO3 destroys the Tb ordering giving rise to a magnetic glass behaviour. This effect is ascribed to the partial polarization of Tb sublattice by the paramagnetic Mn which competes with the direct Tb-Tb exchange.

  16. Synthesis of phase pure BiDyO3 and its structural characterization

    NASA Astrophysics Data System (ADS)

    Iyyapushpam, S.; Nishanthi, S. T.; Padiyan, D. Pathinettam

    2013-02-01

    Phase pure bismuth dysprosium oxide (BiDyO3) is prepared by means of a simple chemical route by varying calcining temperature. Its homogeneous nature is confirmed from XRD and the photocatalytic degradation exists only for the phase pure form of BiDyO3. The crystallite sizes of BiDyO3 calcined at 500, 600 and 700 °C are 9.9, 14.8 and 15.5 nm respectively and this confirms that the materials are in the form of nanocrystalline. For the phase pure BiDyO3 the degradation percentage is found to be 57% in 4 h.

  17. AC-magnetic susceptibility of Dy doped ZnO compounds

    NASA Astrophysics Data System (ADS)

    Akyol, Mustafa; Ekicibil, Ahmet; Kiymaç, Kerim

    2015-07-01

    Dy doped ZnO polycrystalline diluted magnetic semiconductor compounds have been prepared by the so called solid state reaction method. We have studied the M-H and AC magnetic properties of the compounds by using a PPMS magnetometer, and explored the phases and crystal structure by using a X-ray powder diffractometer. The XRD spectra of the compounds show that the substitution of Dy3+ for Zn2+ causes almost no change in the hexagonal wurtzite structure of ZnO, and the Dy3+ ions are successfully substituted into the Zn2+ site of the ZnO matrix. The magnetic measurements, M-H and ?-T, for T in the range from 10 to 300 K, show a paramagnetic behavior, including indirect antiferromagnetic couplings between some Dy3+ magnetic moments. Since the Curie-Weiss temperatures, ?, are all negative but decrease in magnitude with increasing Dy concentration. On the other hand, the calculated effective magnetic moments, ?eff, per Dy3+ ion slowly increase with increasing Dy concentration, but are all very close to the free ion value of ?eff, ~11.0 ?B. Therefore, the trends of the magnitudes of ?s and ?eff s indicate that the samples are not only paramagnetic but also have antiferromagnetic couplings due to the complex nature of the compounds. In addition, the thermal variation of average magnetic moment, Peff(T), per Dy3+ ion have been calculated, and have been found to be gradually increasing with increasing temperature and Dy concentration.

  18. Magnetic order in the double pyrochlore Tb?Ru?O?.

    PubMed

    Chang, L J; Prager, M; Persson, J; Walter, J; Jansen, E; Chen, Y Y; Gardner, J S

    2010-02-24

    Polycrystalline Tb(2)Ru(2)O(7) has been studied using dc susceptibility, specific heat and neutron scattering techniques. The high temperature paramagnetic state is dominated by the single ion character of Tb(3 + ) and very similar to that of the well-studied spin liquid Tb(2)Ti(2)O(7). However, both the Ru(4 + ) and Tb(3 + ) sublattices order, at about 110 K and 3.5 K, respectively. Although the Tb sublattice does not fully order until 3.5 K, it is polarized in the presence of the internal field generated by the Ru(4 + ) sublattice and possesses a significant moment at 7 K. Magnetic entropy measurements suggest that four levels exist in the first 30 K and inelastic neutron scattering investigations revealed two more levels at 10 and 14 meV. As the magnetic sublattices order, the excitations are perturbed from that measured in the paramagnetic state. These data are compared to data for other terbium based and double pyrochlores. PMID:21386400

  19. Challenges and opportunities in developing novel drugs for TB.

    PubMed

    Kaneko, Takushi; Cooper, Christopher; Mdluli, Khisimuzi

    2011-09-01

    Mycobacterium tuberculosis is a difficult pathogen to combat and the first-line drugs currently in use are 40-60 years old. The need for new TB drugs is urgent, but the time to identify, develop and ultimately advance new drug regimens onto the market has been excruciatingly slow. On the other hand, the drugs currently in clinical development, and the recent gains in knowledge of the pathogen and the disease itself give us hope for finding new drug targets and new drug leads. In this article we highlight the unique biology of the pathogen and several possible ways to identify new TB chemical leads. The Global Alliance for TB Drug Development (TB Alliance) is a not-for-profit organization whose mission is to accelerate the discovery and development of new TB drugs. The organization carries out research and development in collaboration with many academic laboratories and pharmaceutical companies around the world. In this perspective we will focus on the early discovery phases of drug development and try to provide snapshots of both the current status and future prospects. PMID:21879843

  20. Ganglioside GD3 promotes cell growth and invasion through p130Cas and paxillin in malignant melanoma cells

    Microsoft Academic Search

    Kazunori Hamamura; Keiko Furukawa; Takanori Hayashi; Takeshi Hattori; Junji Nakano; Hideyuki Nakashima; Tetsuya Okuda; Hideki Mizutani; Hisashi Hattori; Minoru Ueda; Takeshi Urano; Kenneth O. Lloyd; Koichi Furukawa

    2005-01-01

    Although ganglioside GD3 levels are highly elevated in malignant melanomas, the role of GD3 in melanomas' malignant properties has not been clearly shown. To investigate this problem, we genetically generated GD3-positive (GD3+) transfectant cells from a GD3-negative (GD3-) mutant line SK-MEL-28-N1 and analyzed the phenotypic changes in the transfected cells. GD3+ cells showed markedly increased cell growth and invasive characteristics.

  1. High signal contrast gating with biomodified Gd doped mesoporous nanoparticles†

    PubMed Central

    Huang, Wen-Yen; Davies, Gemma-Louise; Davis, Jason J.

    2015-01-01

    Internally Gd doped mesoporous nanoparticles have been prepared and exhibit unprecedented relaxivities that are retained on external biomodification. In tuning diffusive water access, image contrast can be reversibly switched in the presence of a specific protein target. PMID:23164954

  2. DIffusion of Eu and Gd in basalt and obsidian

    Microsoft Academic Search

    Mordeckai Magaritz; Albrecht W. Hofmann

    1978-01-01

    Tracer diffusion coefficients of 153 Gd and 152 Eu in olivine tholeiite have been determined at temperatures between 1150 and 1440°C. The results are identical for both tracers within experimental error. Between 1440 and 1320°C the diffusion coefficients are given by D(Eu, Gd) = 0.058 exp(-40,600\\/ RT). Between 1320 and 1210°C, the diffusion coefficients are constant at D = (1.4

  3. Raman spectra of crystalline and molten GdCl 3

    Microsoft Academic Search

    I. D. Zakir’yanova; A. B. Salyulev

    2010-01-01

    The Raman spectra of crystalline (over a wide temperature range) and molten GdCl3 are mea- sured. The hexagonal structure C\\u000a 2\\u000a 6h (UClC26h3 type) of crystalline GdCl3 is found to change weakly over the entire temperature range under study. The temperature dependences of the characteristic\\u000a frequencies change in the premelting range.

  4. Microwave magnetic resonance in amorphous GdAl films

    Microsoft Academic Search

    J. P. Jamet; A. P. Malozemoff

    1978-01-01

    The microwave absorption spectrum of amorphous sputtered Gd\\/sub x\\/Al\\/sub 1-x\\/ films at 9.13 GHz exhibits a single broad line which is studied as a function of temperature and composition x. In the paramagnetic regime, the g factor has a composition-independent positive shift of 0.006 +- 0.004 above 1.992 of the free Gd\\/sup 3 +\\/ ion, in contrast to negative shifts

  5. Amorphous GdCo disk for thermomagnetic recording

    Microsoft Academic Search

    Y. Togami; K. Kobayashi; M. Kajiura; K. Sato; T. Teranishi

    1982-01-01

    Thermomagnetic recording was carried out on 150-mm-diam amorphous GdCo disks rotated at a speed of 1800 rpm. GdCo films showing good uniformity were deposited on glass disks by rf sputtering technique. Bits as small as 1 ?m in width were recorded, making use of compensation temperature with a laser power of 5.6 mW and were read out with a laser

  6. Unusual low temperature specific heat in ternary Gd intermetallic compounds

    Microsoft Academic Search

    M. J. Parsons; J. Crangle; K.-U. Neumann; K. R. A. Ziebeck

    1998-01-01

    Specific heat measurements are reported for the alloy series Pd2GdxLa1-x In for 0<=x<=1.0, and also for Pd2LuIn and Cu2GdIn. A well defined anomaly associated with the onset of the magnetically ordered state is observed in the specific heat for Pd2GdIn at T=9 K. As x decreases the anomaly becomes broader and the maximum reduces to a lower temperature. Measurements on

  7. Search for Fingerprints of Tetrahedral Symmetry in $^{156}Gd$

    E-print Network

    Q. T. Doan; D. Curien; O. Stezowski; J. Dudek; K. Mazurek; A. Gozdz; J. Piot; G. Duchene; B. Gall; H. Molique; M. Richet; P. Medina; D. Guinet; N. Redon; C. Schmitt; P. Jones; R. Julin; P. Peura; S. Ketelhut; M. Nyman; U. Jakobsson; A. Maj; K. Zuber; P. Bednarczyk; N. Schunck; J. Dobaczewski; A. Astier; I. Deloncle; D. Verney; G. De Angelis; J. Gerl

    2008-12-01

    Theoretical predictions suggest the presence of tetrahedral symmetry as an explanation for the vanishing intra-band E2-transitions at the bottom of the odd-spin negative parity band in $^{156}Gd$. The present study reports on experiment performed to address this phenomenon. It allowed to determine the intra-band E2 transitions and branching ratios B(E2)/B(E1) of two of the negative-parity bands in $^{156}Gd$.

  8. Study on the low-temperature properties of pyrochlores Gd2Hf2O7 and Gd2Zr2O7, using crystal-field theory

    NASA Astrophysics Data System (ADS)

    Ali Biswas, Aksar; Jana, Yatramohan

    2011-07-01

    The geometrically frustrated pyrochlores Gd2Hf2O7 (GdH) and Gd2Zr2O7 (GdZ) are easy planar anisotropic systems in which considerable single-ion crystal-field anisotropies of D3d symmetry are found in the ground multiplet 8S7/2 due to admixture of higher Russell-Saunders terms. The 8S7/2 splits into 4 doublets with total CF splitting 9.9 K in GdH and 9.4 K in GdZ. The magnetic specific heat Cmag follows a conventional T3 behavior in GdH and an unconventional T4.6 behavior in GdZ down to 0.4 K.

  9. Magnetism and hyperfine interactions in Gd 2Ni 2Mg

    NASA Astrophysics Data System (ADS)

    ??tka, Kazimierz; Kmie?, Roman; Pacyna, Andrzej W.; Mishra, Ratikanta; Pöttgen, Rainer

    2001-07-01

    Gd 2Ni 2Mg was synthesised by reaction of the elements in a sealed tantalum tube in a high-frequency furnace. The structure was investigated by single crystal X-ray diffraction: Mo 2FeB 2 type, P4/ mbm, a=743.8(1), c=375.3(1) pm, wR2=0.0560, 256 F2 values, 12 variables. The Gd 2Ni 2Mg structure is an intergrowth of distorted AlB 2 and CsCl slabs of compositions GdNi 2 and GdMg. The magnetic phase transitions were studied by AC and DC magnetic susceptibility measurements and 155Gd Mössbauer spectroscopy. Antiferromagnetic ordering is detected at TN=49.00(5) K followed by two further transitions at Tf1=20.70(5) and Tf2=4.5(1) K, respectively. Non-vanishing second and third harmonic components of the induced voltage under application of a small AC magnetic field reveal the ferromagnetic nature of the second transition at Tf1. Below Tf1, Gd 2Ni 2Mg shows strong irreversibility between field cooled (FC) and zero field cooled (ZFC) DC magnetization and magnetic hysteresis behaviour.

  10. Direct measurement of interlayer interaction in Permalloy/Gd nanodots

    NASA Astrophysics Data System (ADS)

    Lapa, Pavel; Ding, Junjia; Novosad, Valentine; Hoffmann, Axel

    2015-03-01

    Antiferromagnetic interaction at the interfaces of ferromagnetic transition metals(TM) and Gd is well known phenomenon. However, quantitative description of this interaction still lacks understanding. The main reason is that most experimental data were obtained by inspecting the hysteresis loops of TM/Gd multilayers. First, in plane domain structures of TM and Gd films complicates the description of the magnetization reversal process. Second, experimentally measured parameters are averaged over the domains obfuscating the microscopical picture. We make an effort to overcome these limitations by studying the magnetization reversal process of Permalloy/Gd nanodots. The dots were prepared by combination of optical lithography and magnetron sputtering. Experimentally it is observed that in these dots the antiferromagnetic interlayer interaction tunes magnetic vortex nucleation/annihilation fields. Rise of Gd magnetization at low temperature provides unusual temperature behavior of hysteresis loop. Micromagnetic models in which interlayer interaction energy acts as a fitting parameter is applied to simulate experimental hysteresis curves. The effect of nonmagnetic spacer between Permalloy and Gd is also considered and will be presented. This work was supported by the Department of Energy Office of Science, Materials Science and Engineering Division.

  11. Lifetime measurements in the transitional nucleus 138Gd

    NASA Astrophysics Data System (ADS)

    Procter, M. G.; Cullen, D. M.; Ruotsalainen, P.; Braunroth, T.; Dewald, A.; Fransen, C.; Grahn, T.; Greenlees, P. T.; Hackstein, M.; Hauschild, K.; Jakobsson, U.; Jones, P. M.; Julin, R.; Juutinen, S.; Ketelhut, S.; Lopez-Martens, A.; Leino, M.; Litzinger, J.; Mason, P. J. R.; Nieminen, P.; Peura, P.; Rahkila, P.; Reed, M. W.; Rice, S.; Rinta-Antilla, S.; Rother, W.; Sandzelius, M.; Sarén, J.; Scholey, C.; Sorri, J.; Taylor, M. J.; Uusitalo, J.; Vitturi, A.; Shi, Y.; Xu, F. R.

    2011-08-01

    Lifetime measurements have been made in the ground-state band of the transitional nucleus 138Gd from coincidence recoil-distance Doppler-shift data. 138Gd nuclei were produced using the 106Cd (36Ar, 2p2n) reaction with a beam energy of 190 MeV. Reduced transition probabilities have been extracted from the lifetime data collected with the Köln plunger placed at the target position of the JUROGAM-II array. The B(E2) values have been compared with predictions from X(5) critical-point calculations, which describe the phase transition between vibrational and axially symmetric nuclear shapes, as well as with IBM-1 calculations at the critical point. While the excitation energies in 138Gd are consistent with X(5) predictions, the large uncertainties associated with the measured B(E2) values cannot preclude vibrational and rotational contributions to the low-lying structure of 138Gd. Although experimental knowledge for the low-lying ? and ?-vibrational bands in 138Gd is limited, potential-energy surface calculations suggest an increase in ? softness in the ground-state band. In order to more fully account for the effects of ? softness, the X(5) and IBM-1 calculations need to be extended to include the ? degree of freedom for 138Gd.

  12. Judd-Ofelt analysis and emission quantum efficiency of Tb-fluoride single crystals: LiTbF4 and Tb0.81Ca0.19F2.81

    NASA Astrophysics Data System (ADS)

    Vasyliev, V.; Víllora, E. G.; Sugahara, Y.; Shimamura, K.

    2013-05-01

    Terbium is the key element for highly efficient green phosphors and visible-near IR Faraday isolators. We have recently shown the potential of LiTbF4 and Tb0.81Ca0.19F2.81 as visible Faraday rotators. In this work, we present a detail spectroscopic analysis of Tb3+ (4f8) in these two compounds with different crystal structures. By means of the Judd-Ofelt theory, the emission branching ratios and lifetimes of the Tb3+ excited states have been estimated. These results are compared with experimental values obtained for the emitting 5D4 level, as well as with the absolute light yield measurements. Tb3+ in LiTbF4 exhibits a high quantum efficiency, and its radiative lifetime is confirmed to be 7 ms. Instead, the ionic conductor Tb0.81Ca0.19F2.81, which presents a high concentration of vacant sites, shows a lower quantum efficiency and a radiative lifetime about three times larger than estimated. Absorption and emission spectra of Tb0.81Ca0.19F2.81 are broad, so that any fine structure of energy levels can be resolved. In contrast, a detailed study of the splitting of Tb3+ multiplets in Stark energy levels is carried out for LiTbF4.

  13. Antibody response after immunization with the gangliosides GM1, GM2, GM3, GD2 and GD3 in the mouse

    Microsoft Academic Search

    Philip O. Livingston; Gerd Ritter; Michele Jones Calves

    1989-01-01

    The gangliosides GM2, GD2 and GD3 are differentiation antigens expressed on the cell surface of human melanomas and other cancers of neuroectodermal origin. We have compared the antibody response after vaccination with gangliosides GM1, GM2, GM3, GD2 and GD3 in the mouse. Purified gangliosides were injected subcutaneously alone or attached to Salmonella minnesota mutant R595 after pretreatment of the mice

  14. The hydrogenation of Dy{sub 5}Pd{sub 2} followed by in situ methods

    SciTech Connect

    Kohlmann, H., E-mail: h.kohlmann@mx.uni-saarland.de [Inorganic Solid State Chemistry, Saarland University, Am Markt, Zeile 3, 66125 Saarbruecken (Germany); Talik, E. [Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Hansen, T.C. [Institut Laue-Langevin, 6, Rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9 (France)

    2012-03-15

    The hydrogenation behavior of the intermetallic compound Dy{sub 5}Pd{sub 2} was investigated by means of ex situ X-ray powder diffraction, in situ neutron powder diffraction and in situ differential scanning calorimetry. The structural model of Dy{sub 5}Pd{sub 2} with a palladium atom at the 32(e) position x, x, x (x Almost-Equal-To 0.22, 7/8 occupation) and a dysprosium atom at almost the same location (x Almost-Equal-To 0.18, 1/8 occupation) is confirmed. Upon heating the latter approaches x(Pd) and at T=399 K both positional parameters are indistinguishable. Dy{sub 5}Pd{sub 2} does not incorporate hydrogen (deuterium) into its crystal structure, however, starting at T=495 K reacts with hydrogen to non stoichiometric dysprosium dideuteride, DyD{sub 2+x}, following a parabolic rate law. In situ differential scanning calorimetry at various hydrogen pressures up to 2.5 MPa shows strongly exothermic signals, whose temperature onset depend on the gas pressure, corresponding to the formation of a mainly ionic hydride (DyH{sub 2+x}). - Graphical abstract: The hydrogenation of Dy5Pd2 is being followed by in situ neutron diffraction. Highlights: Black-Right-Pointing-Pointer Dy5Pd2 does not form a ternary hydride upon hydrogenation. Black-Right-Pointing-Pointer Dy5Pd2 decomposes to binary hydrides of dysprosium and palladium. Black-Right-Pointing-Pointer At T{>=}399 K Dy3 and Pd in the crystal structure of Dy5Pd2 share the same position. Black-Right-Pointing-Pointer The formation of DyD2+x at T=495 K and p(D2)=2.5 MPa follows a parabolic rate law.

  15. Spin dynamics of Gd at high temperatures

    SciTech Connect

    Cable, J. W.; Nicklow, R. M.

    1989-06-01

    The magnetic excitation spectra of Gd were measured by neutron inelastic scattering over the entire Brillouin zone in the <110> direction at temperatures from 250 to 850 K (/ital T//sub /ital c//=293 K). The data were fitted to a damped-harmonic-oscillator form for the spectral weight function and were placed on an absolute cross-section basis. Wave-vector-dependent susceptibilities were obtained by integration over energy. They clearly show the presence of static spin correlations even at /ital T/=850 K. At /ital T/greater than or equal to/ital T//sub /ital c// we observe a crossover from spin-diffusive motion at small /ital q/ to spin-wave behavior at large /ital q/. The wave vector /ital q//sub /ital c// at which this crossover occurs is determined by the ratio of the damping parameter to the second moment, <..omega../sup 2/>, of the frequency distribution. Surprisingly, <..omega../sup 2/> remains independent of temperature above /ital T//sub /ital c//, and the temperature dependence of /ital q//sub /ital c// is therefore determined by a gradual change in the damping. This results in a very weak /ital q//sub /ital c//-versus-/ital T/ dependence, which is not consistent with a magnetic short-range-order interpretation for the existence of spin waves above /ital T//sub /ital c//.

  16. Operational Challenges in Diagnosing Multi-Drug Resistant TB and Initiating Treatment in Andhra Pradesh, India

    PubMed Central

    Chadha, Sarabjit S.; BN, Sharath; Reddy, Kishore; Jaju, Jyothi; PH, Vishnu; Rao, Sreenivas; Parmar, Malik; Satyanarayana, Srinath; Sachdeva, Kuldeep Singh; Wilson, Nevin; Harries, Anthony D.

    2011-01-01

    Background Revised National TB Control Programme (RNTCP), Andhra Pradesh, India. There is limited information on whether MDR-TB suspects are identified, undergo diagnostic assessment and are initiated on treatment according to the programme guidelines. Objectives To assess i) using the programme definition, the number and proportion of MDR-TB suspects in a large cohort of TB patients on first-line treatment under RNTCP ii) the proportion of these MDR-TB suspects who underwent diagnosis for MDR-TB and iii) the number and proportion of those diagnosed as MDR-TB who were successfully initiated on treatment. Methods A retrospective cohort analysis, by reviewing RNTCP records and reports, was conducted in four districts of Andhra Pradesh, India, among patients registered for first line treatment during October 2008 to December 2009. Results Among 23,999 TB patients registered for treatment there were 559 (2%) MDR-TB suspects (according to programme definition) of which 307 (55%) underwent diagnosis and amongst these 169 (55%) were found to be MDR-TB. Of the MDR-TB patients, 112 (66%) were successfully initiated on treatment. Amongst those eligible for MDR-TB services, significant proportions are lost during the diagnostic and treatment initiation pathway due to a variety of operational challenges. The programme needs to urgently address these challenges for effective delivery and utilisation of the MDR-TB services. PMID:22073182

  17. Gyromagnetic ratios in sup 164 Dy and sup 168 Er

    SciTech Connect

    Doran, C.E. (School of Physics, University of Melbourne, Parkville, Victoria, Australia 3052 (AU)); Stuchbery, A.E. (Department of Nuclear Physics, Research School of Physical Sciences, Australian National University, P.O. Box 4, Canberra, Australia 2601 (AU)); Bolotin, H.H.; Byrne, A.P.; Lampard, G.J. (School of Physics, University of Melbourne, Parkville, Victoria, Australia 3052 (AU))

    1989-11-01

    Gyromagnetic ratios of levels up to 10{sup +} in the ground-state bands and of the 2{sup +} states in the {gamma} bands of {sup 164}Dy and {sup 168}Er were measured by the perturbed angular correlation technique utilizing the transient hyperfine field acting at the nuclei of these ions as they swiftly traversed thin polarized Fe foils. The experimental {ital g} factors, together with the results of earlier similar studies for {sup 166}Er, are discussed and compared with several theoretical predictions.

  18. Yrast Isomers and Possible Oblate Shape in 152Dy

    Microsoft Academic Search

    J. C. Merdinger; F. A. Beck; T. Byrski; C. Gehringer; J. P. Vivien; E. Bozek; J. Styczen

    1979-01-01

    Excitation energies, spins, and parities have been determined for 152Dy in (HI, xn) reactions up to Ipi=27+. Three isomers with T12=49.5 ns (Ex=5035 keV, Ipi=16+), 9.9 ns (Ex=6076 keV, Ipi=20-), and 1.6 ns (Ex=7828 keV, Ipi=26-) have been found. The g factor of the second isomeric state was measured to be g=0.55+\\/-0.06.. The present experimental data compares well with microscopic

  19. Host absorption sensitizing and energy transfer to Eu³? by Gd³? in Ba?Gd{sub 2–x}Na?Eu{sub x}(PO?)?F?

    SciTech Connect

    Xie, Mubiao, E-mail: xiemubiao@yahoo.com.cn [School of Chemistry Science and Technology, Zhanjiang Normal University, Zhanjiang 524048 (China); Liang, Hongbin [MOE Laboratory of Bioinorganic and Synthetic Chemistry, State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Huang, Yan; Gao, Zhenhua; Tao, Ye [Beijing Synchrotron Radiation Facilities, Institute of High Energy Physics, Chinese Academy of Science, Beijing 100039 (China)

    2013-05-01

    Eu³? activated fluoro-apatite phosphors Ba?Gd{sub 2–x}Na?Eu{sub x}(PO?)?F? were synthesized using the traditional high temperature solid state reaction method, and their VUV–vis spectroscopic properties of Eu³? were studied. The results show that phosphor Ba?Gd?.??Na?Eu?.??(PO?)?F? has intense absorption in the VUV range because of Gd³? ions as sensitizers. The energy transfer process from Gd³? to Eu³? in Ba?Gd{sub 2-x}Na?Eu{sub x}(PO?)?F? were investigated and discussed in terms of luminescence spectra and decay curves, showing that the energy transfer of Gd³??Eu³? is efficient. - Graphical abstract: The Gd³? ions can enhance the host-related absorption in VUV range. The energy transfer from Gd³? to Eu³? ions is efficient. Highlights: • The Gd³? ions play an important role in enhancing the host-related absorption in VUV range. • The charge-transfer energy of Eu³? decreases from Ca²? to Sr²? and Ba²? in M?Gd?.??Na?Eu?.??(PO?)?F? (M=Ca, Sr, Ba). • There is efficient energy transfer from Gd³? to Eu³? in Ba?Gd{sub 2–x}Na?Eu{sub x}(PO?)?F?.

  20. Acoustic Faraday effect in Tb_{3}Ga_{5}O_{12}

    Microsoft Academic Search

    A. Sytcheva; U. Löw; S. Yasin; J. Wosnitza; S. Zherlitsyn; P. Thalmeier; T. Goto; P. Wyder; B. Lüthi

    2010-01-01

    The transverse acoustic wave propagating along the [100] axis of the cubic\\u000aTb$_3$Ga$_5$O$_{12}$ (acoustic $c_{44}$ mode) is doubly degenerate. A magnetic\\u000afield applied in the direction of propagation lifts this degeneracy and leads\\u000ato the rotation of the polarization vector - the magneto-acoustic Faraday\\u000arotation. Here, we report on the observation and analysis of the\\u000amagneto-acoustic Faraday-effect in Tb$_3$Ga$_5$O$_{12}$ in