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Sample records for dy tb gd

  1. BaGdF5:Dy(3+),Tb(3+),Eu(3+) multifunctional nanospheres: paramagnetic, luminescence, energy transfer, and tunable color.

    PubMed

    Guan, Hongxia; Song, Yanhua; Zheng, Keyan; Sheng, Ye; Zou, Haifeng

    2016-05-18

    A series of Dy(3+),Tb(3+) and Eu(3+) singly, doubly or triply doped BaGdF5 phosphors were synthesized by a one-step hydrothermal method with l-arginine, and their energy transfer, migrations and multicolored luminescence properties were investigated in detail. The as-prepared Dy(3+),Tb(3+) or Eu(3+) doped samples showed strong blue, green and red emission, respectively. Different hues of green and red light were obtained by co-doped Dy(3+),Tb(3+) and Tb(3+),Eu(3+) in the BaGdF5 host, respectively. More significantly, in the Dy(3+),Tb(3+),Eu(3+) tri-doped BaGdF5 phosphors, colors changed from yellow green to orange red by adjusting the doping concentration of Eu(3+). Energy migrations from Dy(3+) to Tb(3+) and from Tb(3+) to Eu(3+) are reported in detail. Furthermore, the obtained samples exhibit paramagnetic properties at room temperature and low temperature. It is obvious that these Dy(3+), Tb(3+), Eu(3+) singly or doubly or triply doped BaGdF5 nanomaterials with tunable multicolored luminescence properties may have potential applications in the fields of full-color displays, biological labels and bio-separation. PMID:27146322

  2. Complex magnetism of Ho-Dy-Y-Gd-Tb hexagonal high-entropy alloy

    NASA Astrophysics Data System (ADS)

    Lužnik, J.; Koželj, P.; Vrtnik, S.; Jelen, A.; Jagličić, Z.; Meden, A.; Feuerbacher, M.; Dolinšek, J.

    2015-12-01

    Rare earth based equimolar Ho-Dy-Y-Gd-Tb hexagonal high-entropy alloy (HEA) is a prototype of an ideal HEA, stabilized by the entropy of mixing at any temperature with random mixing of elements on the hexagonal close-packed lattice. In order to determine intrinsic properties of an ideal HEA characterized by the enormous chemical (substitutional) disorder on a weakly distorted simple lattice, we have performed measurements of its magnetic and electrical response and the specific heat. The results show that the Ho-Dy-Y-Gd-Tb hexagonal HEA exhibits a rich and complex magnetic field-temperature (H ,T ) phase diagram, as a result of competition among the periodic potential arising from the electronic band structure that favors periodic magnetic ordering, the disorder-induced local random potential that favors spin glass-type spin freezing in random directions, the Zeeman interaction with the external field that favors spin alignment along the field direction, and the thermal agitation that opposes any spin ordering. Three characteristic temperature regions were identified in the (H ,T ) phase diagram between room temperature and 2 K. Within the upper temperature region I (roughly between 300 and 75 K), thermal fluctuations average out the effect of local random pinning potential and the spin system behaves as a pure system of compositionally averaged spins, undergoing a thermodynamic phase transition to a long-range ordered helical antiferromagnetic state at the Néel temperature TN=180 K that is a compositional average of the Néel temperatures of pure Tb, Dy, and Ho metals. Region II (between 75 and 20 K) is an intermediate region where the long-range periodic spin order "melts" and the random ordering of spins in the local random potential starts to prevail. Within the low-temperature region III (below 20 K), the spins gradually freeze in a spin glass configuration. The spin glass phase appears to be specific to the rare earths containing hexagonal HEAs, sharing properties of site-disordered spin glasses and geometrically frustrated (site-ordered) spin systems, as a consequence of strongly interacting large abundant spins of four magnitudes (those of Gd, Tb, Dy, and Ho) on the hexagonal lattice, being weakly diluted by nonmagnetic yttrium atoms.

  3. Influence of Dy3+ coactivator on the luminescence properties of Gd2O2S:Tb3+ phosphor

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Liu, Dachun; Yang, Bin; Zhang, Jinchao; Dai, Yongnian

    2012-01-01

    Gd2O2S:Tb, Dy phosphor were synthesized by co-precipitation method combined with solid-state reactions. The crystal structure and luminescent properties were investigated in this paper. It was confirmed that no new phase was introduced by the analysis of X-ray diffractions (XRD) and fluorescence spectroscopy. It was also illustrated that the lattice size was decreased by doping Dy3+ ions. The results showed that the Dy3+ coactivator had a remarkable influence on the spectral properties of the Gd2O2S:Tb phosphor and can be taken as rare earth ion detector to determine the micro-structure of phosphors. Especially the cross relaxation between Tb3+ and Dy3+ may take place to form the non-radiative energy transfer. Dy3+ as the coactivator added in Gd2O2S:Tb could enhance the luminescence and not disturb its other primary properties. With Dy3+ concentration increased, the intensity of 4F9/2—H13/2 transition at 578 nm was increased further and the emission of 5D4—7FJ transition was highly improved to cause greener emission.

  4. Spin dynamics in i-R 8Mg 42Zn 50 Quasicrystals (R=Gd, Tb, Dy)

    NASA Astrophysics Data System (ADS)

    Charrier, B.; Cotrell, S.; Schmitt, D.

    1999-05-01

    Spin dynamics has been investigated in icosahedral R 8Mg 42Zn 50 quasicrystals (R=Gd, Tb, Dy) by means of muon spin relaxation experiments. Two distinct components are clearly observed, one of them being a fast relaxing signal with a stretched exponential form as in some disordered systems. The corresponding depolarization rate strongly increases when the temperature approaches the ordering temperature TN defined by neutron diffraction experiments. Crystal field effects seem to be noticeable, especially in the dysprosium compound.

  5. 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.

  6. VUV-UV luminescence of Ce3+, Tb3+, Eu3+, and Dy3+ doped GdOCl

    NASA Astrophysics Data System (ADS)

    Li, Yong; Pan, Yan; Chen, Hongmei; Tao, Ye

    2015-12-01

    The vacuum ultraviolet spectroscopic properties of GdOCl:Re3+ (Re3+ = Ce3+, Tb3+, Eu3+, and Dy3+) are investigated in detail for the first time. The host absorption band is determined to be around 179 nm, and the f-d transition bands as well as the charge transfer bands are assigned. Upon 179 nm excitation, Re3+ (Re3+ = Ce3+, Tb3+, Eu3+, Dy3+) ions shown their characteristic emissions. Energy transfers from Gd3+ to Re3+ ion were observed. A broad band ranging from 350 to 400 nm corresponding to the d-f transition of Ce3+ is observed. Eu3+ has typical red emission with the strongest peak at 620 nm; Tb3+ shows characteristic transition of 5D3,4 → 7Fj, and its spin-forbidden and spin-allowed f-d transitions in VUV region are calculated with Dorenbos' equations, these calculated values agree well with the experimental results. Dy3+ presents yellow emission (4F9/2 → 6H13/2) with the strongest peak at 573 nm.

  7. Temperature dependence of the local magnetic momment at a Cd impurity diluted in RZn (R = Gd, Tb and Dy) compounds

    NASA Astrophysics Data System (ADS)

    de Oliveira, A. L.; Chaves, C. M.; de Oliveira, N. A.; Troper, A.

    2016-01-01

    In this work we calculate the local magnetic moment and the related magnetic hyperfine field on a non-magnetic s-p (Cd) impurity diluted in RZn (R = Gd, Tb, and Dy) compounds and their temperature dependence. Both quantities have contributions from the d and f electrons of the rare Earth and from the charge difference between Zn and the impurity ions. We further adopt a functional integral approach in the static approximation to describe the d-d Coulomb interaction arising from the 5d rare Earth ions. The temperatures range from 0 {{K}} up to the critical temperatures T C of the compounds. Our self-consistent results are in good agreement with the available experimental data.

  8. Preparation and characterization of rare earth orthoborates, LnBO{sub 3} (Ln = Tb, La, Pr, Nd, Sm, Eu, Gd, Dy, Y) and LaBO{sub 3}:Gd, Tb, Eu by metathesis reaction: ESR of LaBO{sub 3}:Gd and luminescence of LaBO{sub 3}:Tb, Eu

    SciTech Connect

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

    2011-08-15

    Highlights: {yields} Orthoborates and their solid solutions were prepared by metathesis reaction. {yields} NaCl (by-product) is the driving force for these metathesis reactions. {yields} Structural refinement for TbBO{sub 3} was carried out. {yields} Spin-Hamiltonian parameters of Gd{sup 3+} were deduced from the ESR spectra of LaBO{sub 3}:Gd. -- Abstract: Lanthanide orthoborates of composition LnBO{sub 3} (Ln = Tb, La, Pr, Nd, Sm, Eu, Gd, Dy, Y) and LaBO{sub 3}:Gd, Tb, Eu have been prepared by metathesis reaction. This method provides a convenient route for the synthesis of orthoborates and its solid solutions at low temperatures. Powder X-ray diffraction and FT-IR spectroscopy were used to characterize these borates. Rare earth borates, (LnBO{sub 3}) are isomorphous with different forms of CaCO{sub 3} depending on the radius of rare earth ion. LaBO{sub 3}, LaBO{sub 3}:Gd, Tb, Eu, PrBO{sub 3}, NdBO{sub 3} crystallized in aragonite structure, SmBO{sub 3} crystallized in H-form and TbBO{sub 3}, EuBO{sub 3}, GdBO{sub 3}, DyBO{sub 3}, YBO{sub 3} crystallized in vaterite structure. The structural analysis of TbBO{sub 3} was carried out. The morphology of these borates was obtained from Scanning electron microscopy. Spin-Hamiltonian parameters for Gd{sup 3+} are deduced from room temperature electron spin resonance spectrum of LaBO{sub 3}:Gd. The luminescence of LaBO{sub 3}:Tb, Eu gave characteristics peaks corresponding to Tb{sup 3+}, Eu{sup 3+} respectively.

  9. On the energy transfer in (Y,Gd)Al3(BO3)4:Ln3+ (Ln = Tb3+, Dy3+)

    NASA Astrophysics Data System (ADS)

    Dierkes, Tobias; Pues, Patrick; Jüstel, Thomas

    2015-08-01

    Single-phase (Y,Gd)Al3(BO3)4:Ln3+ (Ln = Tb3+, Dy3+) (YAB) samples were synthesized via solid state reactions and spectroscopic investigations were conducted in order to characterise possible energy transfer mechanisms between Gd3+ and the activator ions, Tb3+/Dy3+. Photoluminescence spectra ranging from 120 to 800 nm were recorded which made it possible to assign charge transfer absorption bands of the host structure, 4f → 5d and 4f → 4f excitations of the activators and their respective emission multiplets. Spectroscopic measurements such as reflection spectra, decay curves, emission/excitation spectra and calculations of external quantum efficiencies were presented to support the suggested energy transfer scheme in Gd3+ activated YAB.

  10. Magnetic structure of R2CoGa8 (R = Gd, Tb, and Dy): Structural tuning of magnetic properties in layered Ga-based intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Mardegan, J. R. L.; Adriano, C.; Vescovi, R. F. C.; Faria, G. A.; Pagliuso, P. G.; Giles, C.

    2014-03-01

    In this work we have determined the magnetic structure of R2CoGa8 (R = Gd, Tb, and Dy) intermetallic compounds using x-ray resonant magnetic scattering in order to study the evolution of the anisotropic magnetic properties along the series for R = Gd-Tm. The three compounds have a commensurate antiferromagnetic spin structure with a magnetic propagation vector τ⃗= (1/2,1/2,1/2) and a Néel temperature of approximately 20, 28.5, and 15.2 K for R = Gd, Tb, and Dy, respectively. The critical exponent β obtained from the temperature dependence of the magnetic peaks suggest a three-dimensional universality class for the three compounds. Comparing the simulated and integrated intensities we conclude that the magnetic moment direction is in the ab plane for the Gd2CoGa8 compound and parallel to the c axis for the Tb2CoGa8 and Dy2CoGa8 compounds. The evolution of the magnetic properties of the R2CoGa8 series for R = Gd-Tm is discussed taking into account the indirect Ruderman-Kittel-Kasuya-Yoshida interaction and crystalline-electric field effects. The comparison between the reported magnetic properties of the Ga-based compounds with those for the In-based isostructural family reveals differences in their exchange couplings that contribute to the understanding of the role of the f-electron magnetism in these classes of materials.

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

    SciTech Connect

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

    2015-05-26

    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.

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

    DOE PAGESBeta

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

    2015-05-26

    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 withmore » 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.« less

  13. Synthesis, characterisation and properties of rare earth oxyselenides A4O4Se3 (A = Eu, Gd, Tb, Dy, Ho, Er, Yb and Y).

    PubMed

    Tuxworth, Andrew J; Wang, Chun-Hai; Evans, John S O

    2015-02-21

    Rare earth oxyselenides A4O4Se3 (A = Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb and Y) were synthesised using solid state reactions and three new structure types (β, γ, and δ) were observed. A4O4Se3 materials adopt either the α (A = Nd, Sm), β (A = Eu), γ (A = Gd, Tb) or δ (A = Dy, Ho, Er, Yb, Y) structure depending on the rare earth radius. Each structure type contains alternating [A2O2](2+) and Se(2-)/Se2(2-) layers. Different ordered and disordered arrangements of Se(2-) and [Se-Se](2-) give the Se layer flexibility and lead to the four different structure types observed. The volume coefficients of expansion for A4O4Se3 ranged from +1.746(9) × 10(-5) to +2.237(3) × 10(-5) K(-1) from 12 to 300 K; no structural phase transitions were observed in this temperature range. Diffuse reflection spectra show A4O4Se3 are semiconductors with band gap Eg 1.02-1.46 eV. Gd4O4Se3, Dy4O4Se3, and Tb4O4Se3 samples show antiferromagnetic ordering with Néel temperature, TN, of 7-9 K. DFT calculations confirm the two different valence states of Se(2-) and Se2(2-) in Eu4O4Se3. PMID:25581725

  14. 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.

  15. Local magnetic moment formation at 119Sn Mössbauer impurity in RCo2 (R=Gd,Tb,Dy,Ho,Er) Laves phase compounds

    NASA Astrophysics Data System (ADS)

    de Oliveira, A. L.; de Oliveira, N. A.; Troper, A.

    2008-04-01

    In this work, we theoretically study the local magnetic moment formation and the systematics of the magnetic hyperfine fields at a Mösbauer Sn119 impurity diluted at the R site (R=Gd,Tb,Dy,Ho,Er) of the cubic Laves phase intermetallic compounds RCo2. One considers that the magnetic hyperfine fields have two contributions, (i) the contribution from R ions, calculated via an extended Daniel-Friedel [J. Phys. Chem. Solids 24, 1601 (1963)] model, and (ii) the contribution from the induced magnetic moments arising from the Co neighboring sites. Our calculated self-consistent total magnetic hyperfine fields are in a good agreement with recent experimental data.

  16. Magnetic structure of R2CoGa8 (R = Gd, Tb and Dy) and evolution of the magnetic structures along the series of intermetallic compounds with R = Gd - Tm

    NASA Astrophysics Data System (ADS)

    Giles, Carlos; Madergan, Jose; Adriano, Cris; Vescovi, Rafael; Pagliuso, Pascoal

    2013-03-01

    In this work we have determined the magnetic structure of R2CoGa8 (R = Gd, Tb and Dy) intermetallic compounds using X-ray resonant magnetic scattering in order to study the evolution of the anisotropic magnetic properties along the series for R = Gd-Tm. The three compounds have a commensurate antiferromagnetic structure with a magnetic propagation vector (1/2 1/2 1/2) with Néel temperatures of 21.0, 27.5 and 15.2 K for R = Gd, Tb and Dy, respectively. The critical exponent β obtained from the temperature dependence of the integrated intensity of the resonant magnetic peaks suggest a 3D magnetism for the three compounds. The energy line shapes at the L2 and L3 edges of the magnetic peaks for these compounds present a purely dipolar character as demonstrated by comparison to first principle calculations. Comparing the simulated and integrated intensities corrected for absorption, we conclude that the magnetic moment direction is in the ab-plane for Gd2CoGa8 compound and parallel to the c - axis for the Tb2CoGa8 and Dy2CoGa8 compounds. This information is used to discuss the evolution of the magnetic structure of R2CoGa8 series for R = Gd-Tm where both the direction of the ordered moment and the ordering temperature evolution along the series can be explained through the competition between the indirect Ruderman-Kittel- Kasuya-Yoshida exchange interaction and crystalline electric field effects.

  17. Homodinuclear lanthanide {Ln2} (Ln = Gd, Tb, Dy, Eu) complexes prepared from an o-vanillin based ligand: luminescence and single-molecule magnetism behavior.

    PubMed

    Bag, Prasenjit; Rastogi, Chandresh Kumar; Biswas, Sourav; Sivakumar, Sri; Mereacre, Valeriu; Chandrasekhar, Vadapalli

    2015-03-01

    Four dinuclear lanthanide complexes [Gd2 (H2L)2 (µ-piv)2 (piv)2]·2CHCl3 (1), [Tb2 (H2L)2 (µ-piv)2 (piv)2]·2CHCl3 (2), [Dy2 (H2L)2 (µ-piv)2 (piv)2]·2CHCl3 (3) and [Eu2 (H2L)2 (µ-piv)2 (piv)2]·2CHCl3 (4) were synthesized by the reaction of appropriate Ln(III) chloride salts and a multidentate ligand, 2,2'-(2-hydroxy-3-methoxy-5-methylbenzylazanediyl)diethanol (H3L) in the presence of pivalic acid. 1-4 are neutral and are held by two monoanionic, [H2L](-) ligands. The two lanthanide ions are doubly bridged to each other via two phenolate oxygen atoms. Both the lanthanide ions are nine coordinated and possess a distorted capped square antiprism geometry. Photophysical studies reveal that Tb(3+) (2) and Dy(3+) (3) complexes display strong ligand-sensitized lanthanide-characteristic emission. The Tb(3+) complex (2) shows a very high overall quantum yield of 76.2% with a lifetime of 1.752 ms. Magnetic studies reveal single-molecule magnet behavior for 3 which shows in its ac susceptibility studies a two-step slow relaxation yielding two effective relaxation energy barriers of ΔE = 8.96 K and 35.51 K. PMID:25641498

  18. Crystal chemistry of the orthorhombic Ln{sub 2}TiO{sub 5} compounds with Ln=La, Pr, Nd, Sm, Gd, Tb and Dy

    SciTech Connect

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

    2015-07-15

    The crystal structures of seven samples of orthorhombic (Pnma) Ln{sub 2}TiO{sub 5} 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 Dy{sub 2}TiO{sub 5} to La{sub 2}TiO{sub 5}. 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–O{sub 3} bonds to opposite corners of the Ti–O{sub 5} square based pyramid polyhedra. For Dy{sub 2}TiO{sub 5} and Tb{sub 2}TiO{sub 5}, a significant variation in Ti–O{sub 1} and Ti–O{sub 4} bond lengths results in an increased deformation of the Ti–O{sub 5} 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. - Graphical abstract: Figure: The crystallographic study of a systematic series of compounds with nominal stoichiometry Ln{sub 2}TiO{sub 5} (with Ln representing La, Pr, Nd, Sm, Gd, Tb and Dy) and orthorhombic, Pnma, symmetry shows changes in cell parameters which fit a linear trend. However, bond lengths are shown to deviate from trend with compounds containing the smaller, heavier lanthanides. - Highlights: • First fabrication and crystallographic refinement of compound Pr{sub 2}TiO{sub 5}. • First systematic study of the crystallography, using S-XRD, for Ln{sub 2}TiO{sub 5} series. • Cation to anion bonding trends and valence states are investigated. • The densities and band-gaps of the series are experimentally determined.

  19. Synthesis and photoluminescence characteristics of (Y,Gd)BO3 :RE (RE = Eu(3+) , Ce(3+) , Dy(3+) and Tb(3+) ) phosphors for blue chip and near-UV white LEDs.

    PubMed

    Rangari, V V; Singh, V; Dhoble, S J

    2016-03-01

    A series of Eu(3+) -, Ce(3+) -, Dy(3+) - and Tb(3+) -doped (Y,Gd)BO3 phosphors was synthesized by a solid-state diffusion method. X-Ray diffraction confirmed their hexagonal structure and the scanning electron microscopy results showed crystalline particles. The excitation spectra revealed that (Y,Gd)BO3 phosphors doped with Eu(3+) , Ce(3+) , Dy(3+) and Tb(3+) are effectively excited with near UV-light of 395 nm/blue light, 364, 351 and 314 nm, respectively. Photoluminescence spectra of Eu(3+) -, Ce(3+) - and Tb(3+) /Dy(3+) -doped phosphor showed intense emission of reddish orange, blue and white light, respectively. The phosphor Y0.60 Gd0.38 BO3 :Ce0.02 showed CIE 1931 color coordinates of (0.158, 0.031) and better color purity compared with commercially available blue BAM:Eu(2+) phosphor. The phosphor (Y,Gd)BO3 doped with Eu(3+) , Dy(3+) and Tb(3+) showed CIE 1931 color coordinates of (0.667, 0.332), (0.251, 0.299) and (0.333, 0.391) respectively. Significant photoluminescence characteristics of the prepared phosphors indicate that they might serve as potential candidates for blue chip and near-UV white light-emitting diode applications. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25991566

  20. Spin-lattice coupling of R1 - xLuxB4 revealing anomalous weak ferromagnetism (R = Sm, Gd, Tb, Dy, Ho)

    NASA Astrophysics Data System (ADS)

    Kang, B. Y.; Lee, Seongsu; Hwang, Sang-Yun; Ji, Sungdae; Song, M. S.; Cho, B. K.

    R B4 (R = rare-earth elements) compounds exhibits antiferromagnetic ordering at low temperature and are classified as the Shastry-Sutherland lattice, which is a geometrically frustrated system. In previous study, it was reported that Y substitution in TbB4 single crystals causes anomalous WF (weak ferromagnetism) even though Y3+ is non-magnetic. The disturbance of a delicate equilibrium in a frustrated system can lead to new electronic and magnetic states. In this study, single crystals of R1-xLuxB4 (R = Sm, Gd, Tb, Dy, Ho), (x =0 ~0.8) were synthesized. WF is also observed. TbB4 went through orthorhombic distortion below Néel temperature. To investigate the existence of orthorhombic distortion in TbLuxB4 (x =0.1, 0.35), high resolution single crystal x-ray diffraction was performed at 5 K. It was confirmed that the distortion was vanished with Lu substitution. Interestingly, lattice constant a was increased with decreasing temperature below the TC. The strong correlation between spin-lattice coupling and WF will be discussed in detail.

  1. Ion-irradiation resistance of the orthorhombic Ln2TiO5 (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb and Dy) series

    NASA Astrophysics Data System (ADS)

    Aughterson, Robert D.; Lumpkin, Gregory R.; Ionescu, Mihail; Reyes, Massey de los; Gault, Baptiste; Whittle, Karl R.; Smith, Katherine L.; Cairney, Julie M.

    2015-12-01

    The response of Ln2TiO5 (where Ln is a lanthanide) compounds exposed to high-energy ions was used to test their suitability for nuclear-based applications, under two different but complementary conditions. Eight samples with nominal stoichiometry Ln2TiO5 (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb and Dy), of orthorhombic (Pnma) structure were irradiated, at various temperatures, with 1 MeV Kr2+ ions in-situ within a transmission electron microscope. In each case, the fluence was increased until a phase transition from crystalline to amorphous was observed, termed critical dose Dc. At certain elevated temperatures, the crystallinity was maintained irrespective of fluence. The critical temperature for maintaining crystallinity, Tc, varied non-uniformly across the series. The Tc was consistently high for La, Pr, Nd and Sm2TiO5 before sequential improvement from Eu to Dy2TiO5 with Tc's dropping from 974 K to 712 K. In addition, bulk Dy2TiO5 was irradiated with 12 MeV Au+ ions at 300 K, 723 K and 823 K and monitored via grazing-incidence X-ray diffraction (GIXRD). At 300 K, only amorphisation is observed, with no transition to other structures, whilst at higher temperatures, specimens retained their original structure. The improved radiation tolerance of compounds containing smaller lanthanides has previously been attributed to their ability to form radiation-induced phase transitions. No such transitions were observed here.

  2. New Materials Derived from Ybco: CrSr2RECu2O8 (RE = La, Pr, Nd, Eu, Gd, Tb, Dy, Y, Ho, Er, Lu).

    PubMed

    Ruiz-Bustos, Rocío; Aguirre, Myriam H; Alario-Franco, Miguel A

    2005-05-01

    Eleven new oxides, derived from yttrium barium copper oxide by replacing the square-planar copper [Cu-O4] of the basal plane of the triple perovskite-based structure with octahedral Cr(IV), have been prepared at high pressure and temperature. Their crystal structures have been determined, and their complex microstructure has been established by means of high-resolution electron microscopy and electron diffraction. The materials have a general formula of CrSr2RECu2O8 (RE = La, Pr, Nd, Eu, Gd, Tb, Dy, Y, Ho, Er, and Lu); they are tetragonal, show the symmetry of space group P4/mmm, and do not appear to be superconducting. PMID:15847410

  3. Production cross sections of elements near the N=126 shell in Ca48-induced reactions with Gd154,Tb159,Dy162, and Ho165 targets

    NASA Astrophysics Data System (ADS)

    Mayorov, D. A.; Werke, T. A.; Alfonso, M. C.; Bennett, M. E.; Folden, C. M.

    2014-08-01

    Excitation functions for shell-stabilized evaporation residues produced in Ca48-induced reactions with Gd154,Tb159,Dy162, and Ho165 targets have been measured in experiments performed at the Cyclotron Institute at Texas A&M University. The examined energy range predominantly covers the 3n and 4n evaporation channels with higher cross sections measured for the 4n products. The σ4n are nearly invariant within experimental uncertainty in reactions with Tb159,Dy162, and Ho165 with the maxima at 12.6 ± 1.9, 12.6 ± 1.7, and 9.4 ± 1.3 mb, respectively. For the reaction with Gd154, the maximum is slightly lower at 4.0 ± 0.6 mb. A simple model to describe the measured production cross sections was employed. Capture was estimated by using the "diffused barrier formula" from the "fusion by diffusion" model proposed by Świątecki et al. [Phys. Rev. C 71, 014602 (2005)]., 10.1103/PhysRevC.71.014602 The fusion probability was estimated by using a phenomenological expression presented by Siwek-Wilczyńska et al. [Int. J. Mod. Phys. E 17, 12 (2008)]., 10.1142/S0218301308009501 The survival probability was calculated according to the formula of Vandenbosch and Huizenga [Nuclear Fission (Academic, New York, 1973)], derived from transition-state theory. The best agreement is reached between calculation and experiment upon inclusion of collective effects in the calculation of the survival probability, shown previously to be important for production of weakly deformed nuclei. This, in turn, challenges the expectation that strong shell stabilization benefits the production cross section. The present data are compared with earlier studies on production of neutron-deficient nuclei in Ca-induced reactions with lanthanide targets.

  4. Synthesis, structure, and magnetism of a family of heterometallic {Cu2Ln7} and {Cu4Ln12} (Ln = Gd, Tb, and Dy) complexes: the Gd analogues exhibiting a large magnetocaloric effect.

    PubMed

    Langley, Stuart K; Moubaraki, Boujemaa; Tomasi, Corrado; Evangelisti, Marco; Brechin, Euan K; Murray, Keith S

    2014-12-15

    The syntheses, structures, and magnetic properties of two heterometallic Cu(II)-Ln(III) (Ln(III) = Gd, Tb, and Dy) families, utilizing triethanolamine and carboxylate ligands, are reported. The first structural motif displays a nonanuclear {Cu(II)2Ln(III)7} metallic core, while the second reveals a hexadecanuclear {Cu(II)4Ln(III)12} core. The differing nuclearities of the two families stem from the choice of carboxylic acid used in the synthesis. Magnetic studies show that the most impressive features are displayed by the {Cu(II)2Gd(III)7} and {Cu(II)4Gd(III)12} complexes, which display a large magnetocaloric effect, with entropy changes -ΔSm = 34.6 and 33.0 J kg(-1) K(-1) at T = 2.7 and 2.9 K, respectively, for a 9 T applied field change. It is also found that the {Cu(II)4Dy(III)12} complex displays single-molecule magnet behavior, with an anisotropy barrier to magnetization reversal of 10.1 K. PMID:25494949

  5. Pechini-type sol-gel synthesis and multicolor-tunable emission properties of GdY(MoO4)3:RE3+ (RE = Eu, Dy, Sm, Tb) phosphors

    NASA Astrophysics Data System (ADS)

    Wang, Dongmei; Fan, Jian; Shang, Mengmeng; Li, Kai; Zhang, Yang; Lian, Hongzhou; Lin, Jun

    2016-01-01

    GdY(MoO4)3:RE3+ (RE = Eu, Dy, Sm, Tb) phosphor were synthesized via a Pechini-type sol-gel process. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL) and cathodoluminescence (CL) spectra, and decay lifetimes etc were utilized to characterize the resulting samples. After annealed at 800 °C for 4 h in air, pure GdY(MoO4)3 phase can form. When the calcination temperature is further increased to 1100 °C, the crystallinity and luminescence intensity reach the best in our experiments. Under UV light and low-voltage electron beam excitation, the GdY(MoO4)3:Eu3+, GdY(MoO4)3:Dy3+, GdY(MoO4)3:Sm3+ and GdY(MoO4)3:Tb3+ phosphors exhibit the characteristic emission of Eu3+ (5D0-7F2, red), Dy3+ (4F9/2-6H13/2, yellow), Sm3+ (4G5/2-6H7/2, orange) and Tb3+ (5D4-7F5, green) with a high color purity, respectively. The Eu3+ and Tb3+ co-doping phosphors are capable of showing color-tunable emissions in the visible region under single-wavelength excitation. The luminescence mechanism and concentration quenching effect were discussed in detail.

  6. Rare earth carbides R{sub 4}C{sub 5} with R = Y, Gd, Tb, Dy, and Ho

    SciTech Connect

    Czekalla, R.; Huefken, T.; Jeitschko, W.

    1997-09-01

    The five carbides R{sub 4}C{sub 5} (R = Y, Gd-Ho) have been prepared by arc-melting cold-pressed pellets of the elemental components and subsequent annealing at 1050{degrees}C. They crystallize with a new orthorhombic structure type (Pbam, Z = 2), which has been determined from X-ray powder diffractometer data of Y{sub 4}C{sub 5} (a = 657.35(9) pm, b = 1191.8(1) pm, c = 366.92(5) pm, R{sub F} = 0.035 for 179 structure factors) and also refined from powder data of Tb{sub 4}C{sub 5} (a = 660.8(1) pm, b = 1197.3(2) pm, c = 368.71(6) pm, R{sub F} = 0.035 for 181 F values) and Ho{sub 4}C{sub 5} (a = 653.00(8) pm, b = 1184.6(1) pm, c = 363.80(4) pm, R{sub F} = 0.036 for 171 F values and 10 positional parameters each). The structure contains building blocks, which were also found in the two closely related structures of {alpha}- and {beta}-Ho{sub 4}C{sub 7}. One-fifth of the carbon atoms are isolated from each other and coordinated octahedrally by rare earth atoms. The other carbon atoms form pairs with C-C bond distances of 133.5(15), 136(3), and 129(2) pm in Y{sub 4}C{sub 5}, Tb{sub 4}C{sub 5}, and Ho{sub 4}C{sub 5}, respectively, corresponding to C-C double bonds. Hence, all valence electrons can be accommodated in bonding R-C and C-C states according to the formula (R{sup +3}){sub 4}(C{sub 2}{sup -4}){sub 2}C{sup -4}, where the superscripts represent oxidation numbers. Nevertheless, the hydrolysis of Y{sub 4}C{sub 5} and Ho{sub 4}C{sub 5} with distilled water resulted in up to 41 wt% ethane, up to 16 wt% propane and propene, and up to 18 wt% higher hydrocarbons in addition to the expected products methane and ethylene.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    Rare-earth (RE=La3+, Nd3+, Gd3+, Tb3+, Dy3+) doped Ba2NiCoRExFe28-xO46 (x=0.25) hexagonal ferrites were synthesized for the first time via micro-emulsion route, which is a fast chemistry route for obtaining nano-sized ferrite powders. These nanomaterials were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), as well as vibrating sample magnetometer (VSM). The XRD analysis exhibited that all the samples crystallized into single X-type hexagonal phase. The crystalline size calculated by Scherrer's formula was found in the range 7-19 nm. The variations in lattice parameters elucidated the incorporation of rare-earth cations in these nanomaterials. FTIR absorption spectra of these X-type ferrites were investigated in the wave number range 500-2400 cm-1. Each spectrum exhibited absorption bands in the low wave number range, thereby confirming the X-type hexagonal structure. The enhancement in the coercivity was observed with the doping of rare-earth cations. The saturation magnetization was lowered owing to the redistribution of rare-earth cations on the octahedral site (3bVI). The higher values of coercivity (664-926 Oe) of these nanomaterials suggest their use in longitudinal recording media.

  8. Pentanuclear heterometallic {Ni2Ln3} (Ln = Gd, Dy, Tb, Ho) assemblies. Single-molecule magnet behavior and multistep relaxation in the dysprosium derivative.

    PubMed

    Chandrasekhar, Vadapalli; Bag, Prasenjit; Kroener, Wolfgang; Gieb, Klaus; Müller, Paul

    2013-11-18

    The reaction between Ln(III) chloride and NiCl2·4H2O salts in presence of a multidentate sterically unencumbered ligand, (E)-2,2'-(2-hydroxy-3-((2-hydroxyphenylimino)methyl)-5-methylbenzylazanediyl)diethanol (LH4) leads to the synthesis of four isostructural pentanuclear hetereometallic complexes [Ni2Dy3(LH)4]Cl (1), [Ni2Gd3(LH)4]Cl (2), [Ni2Tb3(LH)3(LH2)]Cl2 (3), [Ni2 Ho3 (LH)3 (LH2)]Cl2 (4) with unprecedented topology. Here the two compounds 1 are 2 are monocationic and crystallize in chiral space group, P2(1)2(1)2(1) whereas compounds 3 and 4 are dicationic and crystallize in achiral space group P2(1)/n. The total metal framework, {Ni2Ln3} unit is held by four triply deprotonated ligands [LH](3-) in 1 and 2 whereas in case of 3 and 4 three triply deprotonated [LH](3-) and one doubly deprotonated [LH2](2-) ligands are involved. In these complexes both the lanthanide ions and the nickel(II) ions are doubly bridged and the bridging is composed of oxygen atoms derived from either phenolate or ethoxide groups. The analysis of SQUID measurements reveal a high magnetic ground state and a slow relaxation of the magnetization with two relaxation regimes for 1. For the thermally activated regime we found an effective energy barrier of U(eff) = 85 K. Micro Hall probe loop measurements directly proof the single-molecule magnet (SMM) nature of 1 with a blocking temperature of T(B) = 3 K and an open hysteresis for sweep rates faster than 50 mT/s. PMID:24236759

  9. An S-shaped [Fe(4)Dy(2)] complex exhibiting slow relaxation of magnetization: synthesis, magnetism, and crystal structures of a family of [Fe(4)Ln(2)][Ln] coordination compounds (Ln = Nd, Gd, Tb, Dy, and Ho).

    PubMed

    Nayak, Sanjit; Roubeau, Olivier; Teat, Simon J; Beavers, Christine M; Gamez, Patrick; Reedijk, Jan

    2010-01-01

    A series of heterobimetallic 3d-4f cluster coordination compounds has been synthesized using a Schiff-base ligand (H(3)L), a trinuclear iron(III) precursor complex and lanthanide nitrates as reactants. Five new isostructural complexes were prepared with the ligand in 4 different forms, i.e., neutral and 3 different levels of deprotonation, and with the general formula [Fe(III)(4)Ln(III)(2)(H(2)L)(2)(HL)(2)L(2)(CH(3)OH)(2)((CH(3))(3)CCOO)(2)(NO(3))(2)][Ln(III)(NO(3))(4)(H(3)L)(CH(3)OH)].NO(3).H(2)O, where Ln is Nd, Gd, Tb, Dy, and Ho for compounds 1, 2, 3, 4, and 5, respectively. The single-crystal structures of two complexes were determined by X-ray diffraction, consisting of an original [Fe(III)(4)Ln(III)(2)](2+) moiety with a linear S-shaped [Ln-Fe(4)-Ln] core and an isolated Ln(III) ion coordinated by nitrate anions and the neutral Schiff-base ligand. The isostructural nature of all five coordination compounds is further illustrated both by XRPD and IR analysis. Magnetic properties of all five compounds have been studied and are discussed in light of magnetostructural considerations. Among these five compounds, the Dy (4) cluster shows frequency-dependent ac-susceptibility indicative of probable single-molecule magnet behavior. PMID:19954164

  10. Cross sections of proton-induced reactions on 152Gd, 155Gd and 159Tb with emphasis on the production of selected Tb radionuclides

    NASA Astrophysics Data System (ADS)

    Steyn, G. F.; Vermeulen, C.; Szelecsnyi, F.; Kovcs, Z.; Hohn, A.; van der Meulen, N. P.; Schibli, R.; van der Walt, T. N.

    2014-01-01

    Cross sections are presented for various Dy, Tb and Gd radionuclides produced in the proton bombardment of 159Tb as well as for the reactions 152Gd(p,4n)149Tb and 155Gd(p,4n)152Tb up to 66 MeV. The experimental excitation functions are compared with theoretical predictions by means of the geometry-dependent hybrid (GDH) model as implemented in the code ALICE/ASH, as well as with values from the TENDL-2012 library and previous literature experimental data, where available. Physical yields have been derived for the production of some of the medically important radioterbiums, namely 149Tb (radionuclide therapy), 152Tb (PET) and 155Tb (SPECT). The indirect production of high-purity 155Tb via the decay of its precursor 155Dy is reported. The possibility of a large-scale production facility based on a commercial 70 MeV cyclotron is also discussed.

  11. Sensitization of the Gd/sup 3+/ lattice by Pr/sup 3+/ in GdBO/sub 3/ and energy transfer to Ln/sup 3+/ (Ln/sup 3+/ = Dy/sup 3+/, Sm/sup 3+/, and Tb/sup 3+/)

    SciTech Connect

    Srivastava, A.M.; Sobieraj, M.T.; Ruan, S.K.; Banks, E.

    1986-12-01

    The Pr/sup 3+/ ion has been used to sensitize the Gd/sup 3+/ sublattice in GdBO/sub 3/. To obtain efficient photoluminescent materials we have incorporated various activators in the host lattice. These activators are efficient in capturing the migrating Gd/sup 3+/ excitons when excited via the 4f/sup 2/ - 4f5d band of the Pr/sup 3+/ ion. Results have confirmed the transport process Pr/sup 3+/ - Gd/sup 3+/ (- Gd/sup 3+/)n - Ln/sup 3+/, where Ln = Dy/sup 3+/, Sm/sup 3+/, and Tb/sup 3+/. The observation of others has been utilized to predict the emission and excitation spectrum of the 4f/sup 2/ - 4f5d transitions in the Pr/sup 3+/ ion.

  12. Preparation and spectroscopic properties of rare-earth (RE) (RE = Sm, Eu, Tb, Dy, Tm)-activated K{sub 2}LnZr(PO{sub 4}){sub 3} (Ln = Y, La, Gd and Lu) phosphate in vacuum ultraviolet region

    SciTech Connect

    Zhang, Zhi-Jun; Lin, Xiao; Graduate School of Chinese Academy of Science, Beijing, 100039 ; Zhao, Jing-Tai; Zhang, Guo-Bin

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► We report the VUV spectroscopic properties of rare-earth ions in K{sub 2}LnZr(PO{sub 4}){sub 3}. ► The O{sup 2−}-Eu{sup 3+} charge transfer bands at about 220 nm have been observed. ► The 4f–5d spin-allowed and spin-forbidden transitions of Tb{sup 3+} have been observed. ► There is energy transfer between the host and rare-earth activators. -- Abstract: Rare earth (RE = Sm, Eu, Tb, Dy and Tm)-activated K{sub 2}LnZr(PO{sub 4}){sub 3} (Ln = Y, La, Gd and Lu) have been synthesized by solid-state reaction method, and their vacuum ultraviolet (VUV) excitation luminescent characteristics have been investigated. The band in the wavelength range of 130–157 nm and the other one range from 155 to 216 nm with the maximum at about 187 nm in the VUV excitation spectra of these compounds are attributed to the host lattice absorption and O–Zr charge transfer transition, respectively. The charge transfer bands (CTB) of O{sup 2−}-Sm{sup 3+}, O{sup 2−}-Dy{sup 3+} and O{sup 2−}-Tm{sup 3+}, in Sm{sup 3+}, Dy{sup 3+} and Tm{sup 3+}-activated samples, have not been obviously observed probably because the 2p electrons of oxygen are tightly bound to the zirconium ion in the host lattice. For Eu{sup 3+}-activated samples, the relatively weak O{sup 2−}-Eu{sup 3+} CTB at about 220 nm is observed. And for Tb{sup 3+}-activated samples, the bands at 223 and 258 nm are related to the 4f-5d spin-allowed and spin-forbidden transitions of Tb{sup 3+}, respectively. It is observed that there is energy transfer between the host lattice and the luminescent activators (e.g. Eu{sup 3+}, Tb{sup 3+}). From the standpoint of luminescent efficiency, color purity and chemical stability, K{sub 2}GdZr(PO{sub 4}){sub 3}:Sm{sup 3+}, Eu{sup 3+}, Tb{sup 3+} are attractive candidates for novel yellow, red, green-emitting PDP phosphors.

  13. Mo2NiB2-type {Gd, Tb, Dy)2Ni2.35Si0.65 and La2Ni3-type {Dy, Ho}2Ni2.5Si0.5 compounds: Crystal structure and magnetic properties

    NASA Astrophysics Data System (ADS)

    Morozkin, A. V.; Isnard, O.; Nirmala, R.; Malik, S. K.

    2015-05-01

    The crystal structure of new Mo2NiB2-type {Gd, Tb, Dy}2Ni2.35Si0.65 (Immm, No. 71, oI10) and La2Ni3-type {Dy, Ho}2Ni2.5Si0.5 (Cmce No. 64, oC20) compounds has been established using powder X-ray diffraction studies. Magnetization measurements show that the Mo2NiB2-type Gd2Ni2.35Si0.65 undergoes a ferromagnetic transition at 66 K, whereas isostructural Tb2Ni2.35Si0.65 shows an antiferromagnetic transition at 52 K and a field-induced metamagnetic transition at low temperatures. Neutron diffraction study shows that, in zero applied field, Tb2Ni2.35Si0.65 exhibits c-axis antiferromagnetic order with propagation vector K=[1/2, 0, 1/2] below its magnetic ordering temperature and Tb magnetic moment reaches a value of 8.32(5) μB at 2 K. The La2Ni3-type Dy2Ni2.5Si0.5 exhibits ferromagnetic like transition at 42 K with coexisting antiferromagnetic interactions and field induced metamagnetic transition below 17 K. The magnetocaloric effect of Gd2Ni2.35Si0.65, Tb2Ni2.35Si0.65 and Dy2Ni2.5Si0.5 is calculated in terms of isothermal magnetic entropy change and it reaches a maximum value of -14.3 J/kg K, -5.3 J/kg K and -10.3 J/kg K for a field change of 50 kOe near 66 K, 52 K and 42 K, respectively. Low temperature magnetic ordering with enhanced anisotropic effects in Tb2Ni2.35Si0.65 and Dy2Ni2.35Si0.65 is accompanied by a positive magnetocaloric effect with isothermal magnetic entropy changes of +12.8 J/kg K and +9.9 J/kg K, respectively at 7 K for a field change of 50 kOe.

  14. Muon-spin-relaxation studies of magnetic order and dynamics of the n=2 Ruddlesden-Popper phases Sr2RMn2O7 (R=Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Ho)

    NASA Astrophysics Data System (ADS)

    Bewley, R. I.; Blundell, S. J.; Lovett, B. W.; Jestädt, Th.; Pratt, F. L.; Chow, K. H.; Hayes, W.; Battle, P. D.; Green, M. A.; Millburn, J. E.; Rosseinsky, M. J.; Spring, L. E.; Vente, J. F.

    1999-11-01

    Zero field muon spin relaxation (μSR) has been used to study the magnetic properties of n=2 Ruddlesden-Popper phases Sr2RMn2O7, where R=Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Ho. The results show that the size of the lanthanide ion is crucial in determining the magnetic state and dynamics of the system. Because muons are implanted throughout the bulk of the sample, impurity phases contribute only according to their volume fraction. Hence in the case of biphasic samples the data are dominated by the majority phase. Although none of our samples has a ferromagnetic ground state, colossal magnetoresistance (CMR) is observed over a wide temperature range, 4 KGd, Tb, Dy, and Ho. CMR is only observed where μSR measurements show a broad magnetic transition associated with fluctuations. We therefore believe that these fluctuating ordered regions are responsible for the extended temperature regime in which CMR has been observed in these nonferromagnetic n=2 Ruddlesden-Popper phases.

  15. Mo{sub 2}NiB{sub 2}-type (Gd, Tb, Dy){sub 2}Ni{sub 2.35}Si{sub 0.65} and La{sub 2}Ni{sub 3}-type (Dy, Ho){sub 2}Ni{sub 2.5}Si{sub 0.5} compounds: Crystal structure and magnetic properties

    SciTech Connect

    Morozkin, A.V.; Isnard, O.; Nirmala, R.; Malik, S.K.

    2015-05-15

    The crystal structure of new Mo{sub 2}NiB{sub 2}-type (Gd, Tb, Dy){sub 2}Ni{sub 2.35}Si{sub 0.65} (Immm, No. 71, oI10) and La{sub 2}Ni{sub 3}-type (Dy, Ho){sub 2}Ni{sub 2.5}Si{sub 0.5} (Cmce No. 64, oC20) compounds has been established using powder X-ray diffraction studies. Magnetization measurements show that the Mo{sub 2}NiB{sub 2}-type Gd{sub 2}Ni{sub 2.35}Si{sub 0.65} undergoes a ferromagnetic transition at ~66 K, whereas isostructural Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} shows an antiferromagnetic transition at ~52 K and a field-induced metamagnetic transition at low temperatures. Neutron diffraction study shows that, in zero applied field, Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} exhibits c-axis antiferromagnetic order with propagation vector K=[1/2, 0, 1/2] below its magnetic ordering temperature and Tb magnetic moment reaches a value of 8.32(5) μ{sub B} at 2 K. The La{sub 2}Ni{sub 3}-type Dy{sub 2}Ni{sub 2.5}Si{sub 0.5} exhibits ferromagnetic like transition at ~42 K with coexisting antiferromagnetic interactions and field induced metamagnetic transition below ~17 K. The magnetocaloric effect of Gd{sub 2}Ni{sub 2.35}Si{sub 0.65}, Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} and Dy{sub 2}Ni{sub 2.5}Si{sub 0.5} is calculated in terms of isothermal magnetic entropy change and it reaches a maximum value of −14.3 J/kg K, −5.3 J/kg K and −10.3 J/kg K for a field change of 50 kOe near 66 K, 52 K and 42 K, respectively. Low temperature magnetic ordering with enhanced anisotropic effects in Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} and Dy{sub 2}Ni{sub 2.35}Si{sub 0.65} is accompanied by a positive magnetocaloric effect with isothermal magnetic entropy changes of +12.8 J/kg K and ~+9.9 J/kg K, respectively at 7 K for a field change of 50 kOe. - Graphical abstract: The (Gd, Tb, Dy){sub 2}Ni{sub 2.35}Si{sub 0.65} supplement the series of Mo{sub 2}NiB{sub 2}-type rare earth compounds, whereas the (Dy, Ho){sub 2}Ni{sub 2.5}Si{sub 0.5} supplement the series of La{sub 2}Ni{sub 3}-type rare earth compounds. The variation of alloy’s composition by ~3 at% i.e. from Dy{sub 2}Ni{sub 2.35}Si{sub 0.65} to Dy{sub 2}Ni{sub 2.5}Si{sub 0.5} leads to significant transformation of crystal structure of compound with different variant of distortion of Po-type rare earth sublattice, as in Gd–Co–Ga and Er–Ni–In systems: the Mo{sub 2}NiB{sub 2}-type Gd{sub 2}Co{sub 2}Ga and La{sub 2}Ni{sub 3}-type Gd{sub 2}Co{sub 2.9}Ga{sub 0.1}, and Mo{sub 2}FeB{sub 2}-type Er{sub 2}Ni{sub 1.78}In and Mn{sub 2}AlB{sub 2}-type Er{sub 2}Ni{sub 2}In. Magnetization measurements indicate collinear ferromagnetic ordering of Mo{sub 2}NiB{sub 2}-type Gd{sub 2}Ni{sub 2.35}Si{sub 0.65} and a complex antiferromagnetic ordering with low-temperature metamagnetic nature for Mo{sub 2}NiB{sub 2}-type Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} compounds. However, neutron diffraction study in zero applied field of Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} reveals c-axis pure antiferromagnetic ordering of terbium sublattice with K=[1/2, 0, 1/2] propagation vector. Magnetization measurements indicate ferromagnetic order with coexisting antiferromagnetic interactions and low-temperature metamagnetic state for La{sub 2}Ni{sub 3}-type Dy{sub 2}Ni{sub 2.5}Si{sub 0.5}. We suggest possible polymorphism in other Mo{sub 2}FeB{sub 2}-type, Mo{sub 2}NiB{sub 2}-type, La{sub 2}Ni{sub 3}-type and Mn{sub 2}AlB{sub 2}-type rare earth compounds with corresponding change in their magnetic properties. - Highlights: • (Gd, Tb, Dy){sub 2}Ni{sub 2.35}Si{sub 0.65} compounds crystallize in the Mo{sub 2}NiB{sub 2}-type structure. • (Dy, Ho){sub 2}Ni{sub 2.5}Si{sub 0.5} compounds crystallize in the La{sub 2}Ni{sub 3}-type structure. • Gd{sub 2}Ni{sub 2.35}Si{sub 0.65} shows pure ferromagnetic type ordering. • Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} and Dy{sub 2}Ni{sub 2.5}Si{sub 0.5} show mixed ferro-antiferromagnetic ordering. • Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} and Dy{sub 2}Ni{sub 2.5}Si{sub 0.5} exhibit low-temperature metamagnetic behaviour.

  16. Low-temperature superstructures of a series of Cd6M (M = Ca, Y, Sr, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) crystalline approximants.

    PubMed

    Nishimoto, Kazue; Sato, Takeru; Tamura, Ryuji

    2013-06-12

    The low-temperature (LT) superstructure and the phase transition temperature have been investigated for a series of Cd6M crystalline approximants by transmission electron microscopy as well as electrical resistivity measurements. Except for M = Lu, Cd6M is found to undergo a phase transition to a monoclinic phase at a low temperature and the transition temperature (Tc) scales well with the size of the M atom. For M = Ca, Y, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er and Tm the LT superstructure is explained by a ?2a a ?2a lattice with the space group C2/c, and for M = Sr and Yb a ?2a 2a ?2a monoclinic lattice with P2/m. On the other hand, no phase transition is observed for M = Lu, indicating that a Cd4 tetrahedron at the cluster center remains disordered down to the lowest temperature, i.e. 16 K. It is shown that the volume inside the Cd20 dodecahedron plays a crucial role in the occurrence of the phase transition, and long-term aging in particular promotes the phase transition for late rare-earth elements such as Ho, Er and Tm, suggesting that the transition is sensitive to and is even hindered by disorder such as atomic vacancies. The absence of the transition for M = Lu is attributed to the highest activation energy for the transition due to the smallest volume inside the Cd20 dodecahedron. PMID:23685563

  17. Lanthanide salts of heteropoly molybdotungstosilicate LnHSiMo10W2O40·xH2O (Ln = Pr, Nd, Sm, Gd, Tb, Dy, Yb) binding to bovine serum albumin: a fluorescence quenching study.

    PubMed

    Bai, Ai-Min; Ou-Yang, Yu; Yue, Hua-Li; Li, Xiao-Ling; Hu, Yan-Jun

    2012-06-01

    In the present work, the interaction between a series of novel lanthanide salts of heteropoly molybdotungstosilicate LnHSiMo(10)W(2)O(40)·xH(2)O (LnW(2); Ln = Pr (x = 23), Nd (x = 24), Sm (x = 26), Gd (x = 20), Tb (x = 23), Dy (x = 21), Yb (x = 25)), and bovine serum albumin (BSA) was investigated by spectroscopic approach at different temperatures under imitated physiological conditions. In the mechanism discussion, it was proved that the fluorescence quenching of BSA by LnW(2) is a result of the formation of LnW(2)-BSA complex. Binding affinity between LnW(2) and BSA was determined using Scatchard equation and the modified Stern-Volmer equation, and the corresponding electronic structure-affinity relationship were discussed. The results of thermodynamic parameters ∆G, ∆H, ∆S at different temperatures indicate that the electrostatic interactions play a major role in LnW(2)-BSA binding process. Moreover, the enthalpy change (∆H) and entropy change (∆S) were in accordance with the "enthalpy-entropy compensation" equation obtained from this and previous work. Furthermore, the distance r between donor (BSA) and acceptor (LnW(2)) was obtained according to fluorescence resonance energy transfer. PMID:22173815

  18. Amending the anisotropy barrier and luminescence behavior of heterometallic trinuclear linear [M(II) -Ln(III) -M(II) ] (Ln(III) =Gd, Tb, Dy; M(II) =Mg/Zn) complexes by change from divalent paramagnetic to diamagnetic metal ions.

    PubMed

    Das, Sourav; Bejoymohandas, K S; Dey, Atanu; Biswas, Sourav; Reddy, M L P; Morales, Roser; Ruiz, Eliseo; Titos-Padilla, Silvia; Colacio, Enrique; Chandrasekhar, Vadapalli

    2015-04-20

    The sequential reaction of a multisite coordinating compartmental ligand [2-(2-hydroxy-3-(hydroxymethyl)-5-methylbenzylideneamino)-2-methylpropane-1,3-diol] (LH4 ) with appropriate lanthanide salts followed by the addition of [Mg(NO3 )2 ]⋅6 H2 O or [Zn(NO3 )2 ]⋅6 H2 O in a 4:1:2 stoichiometric ratio in the presence of triethylamine affords a series of isostructural heterometallic trinuclear complexes containing [Mg2 Ln](3+) (Ln=Dy, Gd, and Tb) and [Zn2 Ln](3+) (Ln=Dy, Gd, and Tb) cores. The formation of these complexes is demonstrated by X-ray crystallography as well as ESI-MS spectra. All complexes are isostructural possessing a linear trimetallic core with a central lanthanide ion. The comprehensive studies discussed involve the synthesis, structure, magnetism, and photophysical properties on this family of trinuclear [Mg2 Ln](3+) and [Zn2 Ln](3+) heterometallic complexes. [Mg2 Dy](3+) and [Zn2 Dy](3+) show slow relaxation of the magnetization below 12 K under zero applied direct current (dc) field, but without reaching a neat maximum, which is due to the overlapping with a faster quantum tunneling relaxation mediated through dipole-dipole and hyperfine interactions. Under a small applied dc field of 1000 Oe, the quantum tunneling is almost suppressed and temperature and frequency dependent peaks are observed, thus confirming the single-molecule magnet behavior of complexes [Mg2 Dy](3+) and [Zn2 Dy](3+) . PMID:25772122

  19. 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.

  20. 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)

    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.; Ru, N.; Fisher, I.R.

    2010-02-15

    We present a detailed 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 (FS) (up to 0.4eV), 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 2D 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 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, for the first time, 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(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.

  1. Synthesis, structure, luminescent, and magnetic properties of carbonato-bridged Zn(II)2Ln(III)2 complexes [(μ4-CO3)2{Zn(II)L(n)Ln(III)(NO3)}2] (Ln(III) = Gd(III), Tb(III), Dy(III); L(1) = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, L(2) = N,N'-bis(3-ethoxy-2-oxybenzylidene)-1,3-propanediaminato).

    PubMed

    Ehama, Kiyomi; Ohmichi, Yusuke; Sakamoto, Soichiro; Fujinami, Takeshi; Matsumoto, Naohide; Mochida, Naotaka; Ishida, Takayuki; Sunatsuki, Yukinari; Tsuchimoto, Masanobu; Re, Nazzareno

    2013-11-01

    Carbonato-bridged Zn(II)2Ln(III)2 complexes [(μ4-CO3)2{Zn(II)L(n)Ln(III)(NO3)}2]·solvent were synthesized through atmospheric CO2 fixation reaction of [Zn(II)L(n)(H2O)2]·xH2O, Ln(III)(NO3)3·6H2O, and triethylamine, where Ln(III) = Gd(III), Tb(III), Dy(III); L(1) = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, L(2) = N,N'-bis(3-ethoxy-2-oxybenzylidene)-1,3-propanediaminato. Each Zn(II)2Ln(III)2 structure possessing an inversion center can be described as two di-μ-phenoxo-bridged {Zn(II)L(n)Ln(III)(NO3)} binuclear units bridged by two carbonato CO3(2-) ions. The Zn(II) ion has square pyramidal coordination geometry with N2O2 donor atoms of L(n) and one oxygen atom of a bridging carbonato ion at the axial site. Ln(III) ion is coordinated by nine oxygen atoms consisting of four from the deprotonated Schiff-base L(n), two from a chelating nitrate, and three from two carbonate groups. The temperature-dependent magnetic susceptibilities in the range 1.9-300 K, field-dependent magnetization from 0 to 5 T at 1.9 K, and alternating current magnetic susceptibilities under the direct current bias fields of 0 and 1000 Oe were measured. The magnetic properties of the Zn(II)2Ln(III)2 complexes are analyzed on the basis of the dicarbonato-bridged binuclear Ln(III)-Ln(III) structure, as the Zn(II) ion with d(10) electronic configuration is diamagnetic. ZnGd1 (L(1)) and ZnGd2 (L(2)) show a ferromagnetic Gd(III)-Gd(III) interaction with J(Gd-Gd) = +0.042 and +0.028 cm(-1), respectively, on the basis of the Hamiltonian H = -2J(Gd-Gd)ŜGd1·ŜGd2. The magnetic data of the Zn(II)2Ln(III)2 complexes (Ln(III) = Tb(III), Dy(III)) were analyzed by a spin Hamiltonian including the crystal field effect on the Ln(III) ions and the Ln(III)-Ln(III) magnetic interaction. The Stark splitting of the ground state was so evaluated, and the energy pattern indicates a strong easy axis (Ising type) anisotropy. Luminescence spectra of Zn(II)2Tb(III)2 complexes were observed, while those of Zn(II)2Dy(III)2 were not detected. The fine structure assignable to the (5)D4 → (7)F6 transition of ZnTb1 and ZnTb2 is in good accord with the energy pattern from the magnetic analysis. The Zn(II)2Ln(III)2 complexes (Ln(III) = Tb(III), Dy(III)) showed an out-of-phase signal with frequency-dependence in alternating current susceptibility, indicative of single molecule magnet. Under a dc bias field of 1000 Oe, the signals become significantly more intense and the energy barrier, Δ/kB, for the magnetic relaxation was estimated from the Arrhenius plot to be 39(1) and 42(8) K for ZnTb1 and ZnTb2, and 52(2) and 67(2) K for ZnDy1 and ZnDy2, respectively. PMID:24151881

  2. Luminescence and magnetic properties of novel nanoparticle-sheathed 3D Micro-Architectures of Fe0.5R0.5(MoO4)1.5:Ln3+ (R = Gd3+, La3+), (Ln = Eu, Tb, Dy) for bifunctional application

    NASA Astrophysics Data System (ADS)

    Krishnan, Rajagopalan; Thirumalai, Jagannathan; Kathiravan, Arunkumar

    2015-01-01

    For the first time, we report the successful synthesis of novel nanoparticle-sheathed bipyramid-like and almond-like Fe0.5R0.5(MoO4)1.5:Ln3+ (R = Gd3+, La3+), (Ln = Eu, Tb, Dy) 3D hierarchical microstructures through a simple disodium ethylenediaminetetraacetic acid (Na2EDTA) facilitated hydrothermal method. Interestingly, time-dependent experiments confirm that the assembly-disassembly process is responsible for the formation of self-aggregated 3D architectures via Ostwald ripening phenomena. The resultant products are characterized by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), photoluminescence (PL), and magnetic measurements. The growth and formation mechanisms of the self-assembled 3D micro structures are discussed in detail. To confirm the presence of all the elements in the microstructure, the energy loss induced by the K, L shell electron ionization is observed in order to map the Fe, Gd, Mo, O, and Eu components. The photo luminescence properties of Fe0.5R0.5(MoO4)1.5 doped with Eu3+, Tb3+, Dy3+ are investigated. The room temperature and low temperature magnetic properties suggest that the interaction between the local-fields introduced by the magnetic Fe3+ ions and the R3+ (La, Gd) ions in the dodecahedral sites determine the magnetism in Fe0.5R0.5(MoO4)1.5:Eu3+. This work provides a new approach to synthesizing the novel Fe0.5R0.5(MoO4)1.5:Ln3+ for bi-functional magnetic and luminescence applications.

  3. 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.

  4. β-decay half-lives of new neutron-rich isotopes 167,168Tb and levels in 167,168Dy

    NASA Astrophysics Data System (ADS)

    Asai, M.; Ichikawa, S.; Tsukada, K.; Sakama, M.; Shibata, M.; Kojima, Y.; Osa, A.; Nishinaka, I.; Nagame, Y.; Kawade, K.; Tachibana, T.

    1999-06-01

    β-decay half-lives of new neutron-rich isotopes 167Tb and 168Tb produced in the 20 MeV proton-induced fission of 238U have been determined to be 19.4(27) s and 8.2(13) s, respectively, using a gas-jet coupled on-line isotope separator. The present half-lives and those of the recently identified nuclei 159Pm, 161Sm, 165Gd, 166Tb were compared with theoretical predictions. The recent calculation by the gross theory with the new one-particle strength functions shows quite good agreement with the experimental half-lives. Excited states of the daughter nuclides 167Dy and 168Dy have been established for the first time. Level energies of the first 2+ states in even-even Dy isotopes were found to show an irregular behavior at 164Dy and increasing deformation toward the neutron midshell around N~104.

  5. Physical properties of RMg2Cu9 (R = Y, Ce-Nd, Gd-Dy)

    NASA Astrophysics Data System (ADS)

    Kong, Tai; Bud'Ko, Sergey; Canfield, Paul

    R Mg2Cu9 is a family of hexagonal compounds with a single rare earth site that has a 6 m2 local symmetry. In this talk, magnetic, electric transport and specific heat data measured on single crystals of RMg2Cu9 synthesized using Ta crucible will be presented and discussed. Due to a strong CEF effect, all local moment bearing members (except for isotropic GdMg2Cu9) in the present study show a higher magnetic susceptibility when external field is applied along the ab-plane than along the c-axis. For R = Ce, Nd, Gd-Dy, the compounds order antiferromagnetically above 2 K. The ordering temperature deviates from de Gennes scaling with GdMg2Cu9 ordering at a lower temperature than TbMg2Cu9. PrMg2Cu9 does not order magnetically down to 2 K and might have a singlet ground state. This series of compounds offer an opportunity to study in-plane anisotropy of rare earth in a hexagonal CEF configuration, following our previous work on in-plane 4-state clock model in a tetragonal system, for example: HoNi2B2C (P.C. Canfield et al. PRB 55, 970) and DyAgSb2 (K.D. Myers et al. PRB 59, 1121). This work is supported by the US DOE, Basic Energy Sciences under Contract No. DE-AC02-07CH11358.

  6. 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.

    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 β≈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.

  7. Sol-precipitation-hydrothermal synthesis and luminescence of GdPO4:Tb3+ submicron cubes

    NASA Astrophysics Data System (ADS)

    Cao, Yanyan; Sun, Peng; Liang, Yingmin; Wang, Rongrong; Zhang, Xiao

    2016-05-01

    GdPO4:Tb3+ submicron cubes were synthesized by a sol-precipitation-hydrothermal process. The XRD result indicated that GdPO4:Tb3+ submicron cubes have pure hexagonal phase. The SEM and TEM images confirmed the formation of cubic morphology. Under the excitation at 273 nm, GdPO4:Tb3+ submicron cubes show emission bands corresponding to Gd3+ and Tb3+. With the increasing Tb3+ concentration, the emission intensities originating from Gd3+ and 5D3 → 7Fj transition of Tb3+ decrease, but the emission intensities originating from 5D4 → 7Fj transition of Tb3+ increase. These results suggested energy transfer from Gd3+ to Tb3+ and the occurrence of cross-relaxation processes in GdPO4:Tb3+ submicron cubes.

  8. 155Gd and 161Dy Mössbauer study of R 1+ɛFe 4B 4 alloys (R = Gd, Dy)

    NASA Astrophysics Data System (ADS)

    Rechenberg, H. R.; Bogé, M.; Jeandey, C.; Oddou, J. L.; Sanchez, J. P.; Tenaud, P.

    1987-10-01

    Tetragonal R 1+ɛFe 4B 4 alloys with R = Gd and Dy have been investigated by Mössbauer spectroscopy, using the 155Gd and 161Dy resonances, respectively. The Gd quadrupolar interaction e2qQ = 12.65(5) mm/ s is the largest observed to date in metallic compounds of Gd. For Dy this interaction is e 2qQ = 74(2) mm/s, a value rather small for a Dy compound. Both results imply a strong lattice contribution to the electric field gradient. A crystal-field term A02 = -2450(50) K/ a2o is inferred. Our data are consistent with a point-charge calculation, provided charges of opposite signs are assumed for Fe and B atoms. Hyperfine parameters show some dispersion, reflecting the quasi incommensurate nature of the R and Fe+B sublattices in the R 1+ɛFe 4B 4 structure.

  9. 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

  10. [VUV spectral properties of (Y, Gd) Al3 (BO3)4: Tb].

    PubMed

    Liu, Duan-yang; He, Da-wei; Kang, Kai; Liu, Chun-tang; Li, Shao-xia; Shen, Fang; Tao, Ye

    2005-07-01

    (Y, Gd)A13 (BO3)4 doped with Ce and Tb were prepared by solid state reaction. The structure, VUV excitation properties, excitation were studied. (Y,Gd)Al3 (BO3)4 belongs to trigonal crystal system with thespace group of R32, and the crystal structure does not change as Tb3+ and Ce3+ ions are doped to the crystal lattice. The host absorption band of (Y,Gd)Al3 (BO3)4:Tb moves to longer wavelength as Gd3+ mol concentration increases. The energy transfer between Gd3+ and Tb3+ is very effective, and the samples with high Gd3+ mol concentrations have high radiant efficiencies. It was found that the luminescence of Tb3+ is quenched by Ce3+ in (Y,Gd)Al3(BO3)4:Ce, Tb under VUV excitation. PMID:16241048

  11. Magnetic order of Y3NiSi3-type R3NiSi3 (R=Gd-DY) compounds

    NASA Astrophysics Data System (ADS)

    Morozkin, A. V.; Yapaskurt, V. O.; Nirmala, R.; Malik, S. K.; Quezado, S.; Yao, Jinlei; Mozharivskyj, Y.; Nigam, A. K.; Isnard, O.

    2016-01-01

    Magnetic measurements and neutron powder diffraction investigations on the Y3NiSi3-type R3NiSi3 compounds (R=Gd, Tb, Dy) reveal their complex antiferromagnetic ordering. Magnetic measurements on Gd3NiSi3, Tb3NiSi3 and Dy3NiSi3 indicate antiferromagnetic-like transition at temperatures 260 K, 202 K and 140 K, respectively. Also, the Tb3NiSi3 and Dy3NiSi3 compounds show spin-reorientation transition at 132 K and 99 K, respectively. Below the spin-reorientation transition, the isothermal magnetization curves indicate the metamagnetic-like behavior of Tb3NiSi3 and Dy3NiSi3. The magnetocaloric effect of Dy3NiSi3 is calculated in terms of isothermal magnetic entropy change and it reaches a maximum value of -1.2 J/kg K and -1.1 J/kg K for a field change of 50 kOe near 146 K and 92 K, respectively. The neutron diffraction studies of Tb3NiSi3 suggest the magnetic ordering of the Tb2 4j sublattice and no magnetic ordering of the Tb1 2a sublattice. Tb3NiSi3 transforms from the high temperature paramagnetic state to the commensurate high-temperature a- and c-axis antiferromagnet of I‧2/m magnetic space group below 250 K. Below 150 K, the high-temperature antiferromagnet transforms into the low-temperature a-, b- and c-axis antiferromagnet of I‧i magnetic space group. At 1.5 K, the terbium magnetic moment in Tb2 sublattice and its a-, b- and c-axis components reach the values of MTb2=8.2(1) μB, MaTb2=5.9(1) μB, MbTb2=4.3(2) μB and McTb2=3.7(2) μB, respectively.

  12. Spin response of magnetic dipole transitions in 156Gd and 164Dy

    NASA Astrophysics Data System (ADS)

    Frekers, D.; Bohle, D.; Richter, A.; Abegg, R.; Azuma, R. E.; Celler, A.; Chan, C.; Drake, T. E.; Jackson, K. P.; King, J. D.; Miller, C. A.; Schubank, R.; Watson, J.; Yen, S.

    1989-03-01

    Intermediate energy proton scattering has been used to probe the spin part of the recently discovered low-lying isovector magnetic dipole transitions in the rotational rare earth nuclei 156Gd and 164Dy. A large spin response is found in 164Dy, whereas in 156Gd the results are consistent with the picture of a predominantly convective excitation. The results are discussed in the context of the IBA-2 model and recent RPA calculations.

  13. 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; Blanco, M. Cecilia; Fuertes, Valeria C.; Pannunzio-Miner, Elisa V.; Carbonio, Raúl E.

    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.

  14. Solvothermal syntheses, crystal structures, and properties of lanthanide(III) thioarsenates [Ln(dien)2(μ-1κ,2κ2-AsS4)]n (Ln==Sm, Eu, Gd) and [Ln(dien)2(1κ2-AsS4)] (Ln==Tb, Dy, Ho)

    NASA Astrophysics Data System (ADS)

    Wang, Fang; Tang, Chunying; Chen, Ruihong; Zhang, Yong; Jia, Dingxian

    2013-10-01

    Solvothermal reactions of Ln2O3, As and S in diethylenetriamine (dien) at 170 °C for 6 days afforded two structural types of lanthanide thioarsenates with the general formulae [Ln(dien)2(μ-1κ,2κ2-AsS4)]n [Ln=Sm(1), Eu(2), Gd(3)] and [Ln(dien)2(1κ2-AsS4)] [Ln=Tb(4), Dy(5), Ho(6)]. The Ln2O3 oxides were converted to [Ln(dien)2]3+ complex units in the solvothermal reactions. The As atom binds four S atoms, forming a tetrahedral AsS4 unit. In 1-3, the AsS4 units interconnect the [Ln(dien)2]3+ cations via Ln-S bonds as tridentate μ-1κ,2κ2-AsS4 bridging ligands, resulting in the neutral coordination polymers [Ln(dien)2(μ-1κ,2κ2-AsS4)]n (Ln1). In 4-6, the AsS4 units coordinate with the Ln3+ ion of [Ln(dien)2]3+ as 1κ2-AsS4 chelating ligands to form neutral coordination compounds [Ln(dien)2(1κ2-AsS4)] (Ln2). The Ln3+ ions are in nine- and eight-coordinated environments in Ln1 and Ln2, respectively. The formation of Ln1 and Ln2 is related with ionic size of the Ln3+ ions. Optical absorption spectra showed that 1-6 have potential use as semiconductors with the band gaps in the range 2.18-3.21 eV.

  15. New nuclide 139Tb and (EC +β+) decay of 138,139Gd

    NASA Astrophysics Data System (ADS)

    Yuanxiang, Xie; Shuwei, Xu; Zhankui, Li; Yong, Yu; Qiangyan, Pan; Chunfang, Wang; Tianmei, Zhang

    The unknown isotope 139Tb and the known isotopes 138,139Gd were produced in the 36Ar+106Cd reaction and studied by using a He-jet tape transport system in combination with X-γ and γ-γ coincidence measurements. The half-lives of 139Tb, 139gGd, 139mGd and 138Gd were determined to be 1.6(2), 5.8(9), 4.8(9) and 4.7(9) s, respectively. Partial (EC+β+) decay schemes of 139gGd, 139mGd and 138Gd were proposed for the first time.

  16. Random anisotropy causes wide distributions of relaxation rates in Tb-Mg-Zn quasicrystals and amorphous DyAg

    NASA Astrophysics Data System (ADS)

    Noakes, D. R.; Kalvius, G. M.; Hartmann, O.

    2002-04-01

    ``Power-exponential'' zero-field (ZF) muon spin relaxation (μSR), where the power varies with temperature, as observed in icosahedral Tb8Mg42Zn50 and in amorphous (am-)DyAg, is shown to be consistent with a wide distribution of relaxation rates by construction of a closed-form relaxation function representing such a distribution that fits the μSR data. This relaxation function is obtained by Laplace transform of a ``double-square'' distribution of relaxation rates, an example of a distribution that is asymmetric about its mean so that its width can be larger than that mean, a property that is necessary to fit the more extremely nonexponential cases. Combination with the results of 161Dy Mössbauer effect measurements in DyAg indicates that this behavior is due to random axial crystalline electric-field (CEF) anisotropy. In addition to creating the random distribution of moment pointing directions in the asperomagnetic ordered state of am-DyAg, this creates a wide distribution of splittings between the Jz=J ground doublet and the first excited state, thus causing a wide distribution of rare-earth paramagnetic fluctuation rates, leading to the wide distribution of muon spin relaxation rates deduced above. The contrast of simple-exponential ZF-μSR in i-Gd8Mg42Zn50 with double-square-distribution relaxation in the Tb quasicrystal clearly indicates that a CEF mechanism, probably the same one, is causing the nonexponential relaxation in the Tb quasicrystal, as well.

  17. 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.

  18. Extreme ultraviolet emission spectra of Gd and Tb ions

    SciTech Connect

    Kilbane, D.; O'Sullivan, G.

    2010-11-15

    Theoretical extreme ultraviolet emission spectra of gadolinium and terbium ions calculated with the Cowan suite of codes and the flexible atomic code (FAC) relativistic code are presented. 4d-4f and 4p-4d transitions give rise to unresolved transition arrays in a range of ions. The effects of configuration interaction are investigated for transitions between singly excited configurations. Optimization of emission at 6.775 nm and 6.515 nm is achieved for Gd and Tb ions, respectively, by consideration of plasma effects. The resulting synthetic spectra are compared with experimental spectra recorded using the laser produced plasma technique.

  19. Solvothermal syntheses, crystal structures, and properties of lanthanide(III) thioarsenates [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} (Ln==Sm, Eu, Gd) and [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] (Ln==Tb, Dy, Ho)

    SciTech Connect

    Wang, Fang; Tang, Chunying; Chen, Ruihong; Zhang, Yong; Jia, Dingxian

    2013-10-15

    Solvothermal reactions of Ln{sub 2}O{sub 3}, As and S in diethylenetriamine (dien) at 170 °C for 6 days afforded two structural types of lanthanide thioarsenates with the general formulae [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} [Ln=Sm(1), Eu(2), Gd(3)] and [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] [Ln=Tb(4), Dy(5), Ho(6)]. The Ln{sub 2}O{sub 3} oxides were converted to [Ln(dien){sub 2}]{sup 3+} complex units in the solvothermal reactions. The As atom binds four S atoms, forming a tetrahedral AsS{sub 4} unit. In 1−3, the AsS{sub 4} units interconnect the [Ln(dien){sub 2}]{sup 3+} cations via Ln−S bonds as tridentate μ-1κ,2κ{sup 2}-AsS{sub 4} bridging ligands, resulting in the neutral coordination polymers [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} (Ln1). In 4−6, the AsS{sub 4} units coordinate with the Ln{sup 3+} ion of [Ln(dien){sub 2}]{sup 3+} as 1κ{sup 2}-AsS{sub 4} chelating ligands to form neutral coordination compounds [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] (Ln2). The Ln{sup 3+} ions are in nine- and eight-coordinated environments in Ln1 and Ln2, respectively. The formation of Ln1 and Ln2 is related with ionic size of the Ln{sup 3+} ions. Optical absorption spectra showed that 1−6 have potential use as semiconductors with the band gaps in the range 2.18−3.21 eV. - Graphical abstract: Two types of Ln-thioarsenates [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} and [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] were prepared by solvothermal methods and the soft Lewis basic AsS{sub 4}{sup 3–} ligand to Ln(III) centers with polyamine co-ligand was obtained. Display Omitted - Highlights: • Lanthanide thioarsenates were prepared by solvothermal methods. • The soft Lewis basic AsS{sub 4} ligand coordinate Ln{sup 3+} ions with coexistence polyamine ligands. • Two structural types of Ln-thioarsenates with structural turnover at Tb were obtained along Ln series. • The Ln-thioarsenates are potential semiconductors with optical band gaps in the range 2.18−3.21 eV.

  20. Defect-dicubane Ni2Ln2 (Ln = Dy, Tb) single molecule magnets.

    PubMed

    Mondal, Kartik Chandra; Kostakis, George E; Lan, Yanhua; Wernsdorfer, Wolfgang; Anson, Christopher E; Powell, Annie K

    2011-11-21

    Two pairs of Ni(2)Dy(2) and Ni(2)Tb(2) complexes, [Ni(2)Ln(2)(L)(4)(NO(3))(2)(DMF)(2)] {Ln = Dy (1), Tb (2)} and [Ni(2)Ln(2)(L)(4)(NO(3))(2)(MeOH)(2)]·3MeOH {Ln = Dy (3), Tb (4)} (H(2)L is the Schiff base resulting from the condensation of o-vanillin and 2-aminophenol) possessing a defect-dicubane core topology were synthesized and characterized. All four complexes are ferromagnetically coupled, and the two Dy-analogues are found to be Single Molecule Magnets (SMMs) with energy barriers in the range 18-28 K. Compound 1 displays step-like hysteresis loops, confirming the SMM behavior. Although 1 and 3 show very similar structural topologies, the dynamic properties of 1 and 3 are different with blocking temperatures (3.2 and 4.2 K at a frequency of 1500 Hz) differing by 1 K. This appears to result from a change in orientation of the nitrate ligands on the Dy(III) ions, induced by changes in ligands on Ni(II). PMID:22022951

  1. Spectroscopy and energy transfer in lead borate glasses doubly doped with Dy3+-Tb3+ and Tb3+-Eu3+ ions

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    Lead borate glasses doubly doped with Dy3+-Tb3+ and Tb3+-Eu3+ were investigated using optical spectroscopy. Luminescence spectra of rare earths were detected under various excitation wavelengths. The main green emission band due to 5D4 → 7F5 transition of Tb3+ is observed under excitation of Dy3+, whereas the main red emission band related to 5D0 → 7F2 transition of Eu3+ is successfully observed under direct excitation of Tb3+. In both cases, the energy transfer processes from Dy3+ to Tb3+ and from Tb3+ to Eu3+ 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.

  2. 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

  3. Preparation and luminescent properties of GdOF:Ce, Tb nanoparticles and their transparent PMMA nanocomposites

    NASA Astrophysics Data System (ADS)

    Cai, Wen; Wang, Aiwu; Fu, Li; Hu, Jie; Rao, Tingke; Wang, Junqing; Zhong, Jiasong; Xiang, Weidong

    2015-05-01

    GdOF:Ce, Tb nanoparticles and their poly (methyl methacrylate) (PMMA) nanocomposites have been successfully prepared by a thermolysis route and thermal polymerization of methyl methacrylate (MMA) monomer, respectively. The obtained nanoparticles and nanocomposites are characterized by XRD, EDS, TEM, FTIR, TGA, UV-Vis and PL spectrum. The as-synthesized transparent GdOF:Ce, Tb/PMMA nanocomposites exhibit green photoluminescence under the irradiation of 254 nm UV lamp due to the incorporation of luminescent GdOF:Ce, Tb nanoparticles into the PMMA matrix. The present route would provide a general strategy to prepare other functional nanocomposites.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    The total cross sections for the 152Gd(p ,γ )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 γ -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.

  5. Magnetic Properties of RB66 (R = Gd, Tb, Ho, Er, and Lu)

    SciTech Connect

    Kim, Hyunsoo; Budko, Serguei; ATanatar, Makariy; Avdashchenko, D.V.; Matovnikov, A.V.; Mitroshenkov, N.V.; Novikov, V.V.; Prozorov, Ruslan

    2012-05-17

    We report magnetic susceptibility measurements of RB66 (R = Gd, Tb, Ho, Er, and Lu) boron-rich rare earth containing borides down to 50 mK. The data suggest a spin glass low temperature state for RB66 (R = Gd, Tb, Ho, and Er) with the freezing temperatures below 1 K. The magnetic properties appear to be influenced by the anisotropy of the magnetic moments, probably via the crystalline electric field effects.

  6. Magneto caloric effect in (Dy xGd 1- x) 3Ga 5O 12 for adiabatic demagnetization refrigeration

    NASA Astrophysics Data System (ADS)

    Numazawa, Takenori; Kamiya, Koji; Okano, Takahiro; Matsumoto, Koichi

    2003-05-01

    Gadolinium and dysprosium gallium garnet single crystals ( DyxGd1-x) 3Ga5O12 (x=0,0.5 and 1) have been investigated for adiabatic demagnetization refrigeration used as magnetic materials between 0.5 and 5 K. Specific heat measurement of (Dy 0.5Gd 0.5) 3Ga 5O 12 showed a large and broad peak similar to that of Gd 3Ga 5O 12 and it suggests that the geometrical frustration in Gd 3Ga 5O 12 still remains in (Dy 0.5Gd 0.5) 3Ga 5O 12. Magneto caloric effect of (Dy 0.5Gd 0.5) 3Ga 5O 12 was about four times larger than that of Gd 3Ga 5O 12 for the magnetic field of 1 T between 0.5 and 5 K. Therefore, the magnetic entropy change of Gd 3Ga 5O 12 by the external magnetic fields could be enhanced by substituting Dy 3+ ion for Gd 3+ ion for the magnetic fields of <2 T between 0.5 and 5 K.

  7. Thermochemical properties of Ln2BaCoO5 (Ln = Nd, Gd, Dy, Ho)

    NASA Astrophysics Data System (ADS)

    Tiflova, L. A.; Kovba, M. L.; Monaenkova, A. S.

    2015-04-01

    The enthalpies of the reactions of double rare-earth and barium cobaltites Ln2BaCOO5 (Ln = Nd, Gd, Dy, Ho) and metallic dysprosium with 1 M hydrochloric acid are measured at 298.15 K using precision calorimetric equipment. The standard enthalpies of formation of Ln2BaCoO5 from simple components and binary oxides were calculated from the obtained results and reliable literature data.

  8. 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

  9. 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.

  10. Mn substitution effect on magnetostriction temperature dependence in Tb0.3Dy0.7Fe2

    NASA Astrophysics Data System (ADS)

    Funayama, T.; Kobayashi, T.; Sakai, I.; Sahashi, M.

    1992-07-01

    Magnetostriction temperature dependencies in Tb0.3Dy0.7 (Fe1-xMnx)2 were investigated. Mn substitution lowers the spin reorientation temperature, at which magnetostriction shows a sharp drop. Moreover, Mn containing compounds show larger magnetostriction than that for a Mn-free compound at low temperature. Mössbauer measurements show that easy magnetization direction for the Mn containing compound is in the <111> direction at 300 K, while it is in the <100> at 77 K. These results indicate that the tetragonal distortion λ100 increases by Mn addition in Tb0.3Dy0.7Fe2.

  11. White light generation in Tb3+/Eu3+/Dy3+ triply-doped Zn(PO3)2 glass

    NASA Astrophysics Data System (ADS)

    Meza-Rocha, A. N.; Lozada-Morales, R.; Speghini, A.; Bettinelli, M.; Caldiño, U.

    2016-01-01

    A spectroscopic investigation of Tb3+/Eu3+/Dy3+ triply-doped Zn(PO3)2 glass focused on generation of white light is performed through photoluminescence spectra and decay time measurements. The white light emission obtained in the glass phosphor shows excitation wavelength dependent tunable tonality: neutral white (0.385, 0.441) of 4250 K and warm white (0.417, 0.412) of 3429 K, upon 445 and 322 nm excitations, respectively. A quantum yield of 26.1 ± 1.2% is attained upon Dy3+ excitation at 445 nm. The white luminescence is due mainly to terbium 5D4 → 7F5, dysprosium 4F9/2 → 6H15/2,13/2 and europium 5D0 → 7F2 transitions. It is demonstrated that non-radiative energy transfers Dy3+ to Tb3+ and Eu3+, and Tb3+ to Eu3+, take place in the glass phosphor excited at 445 or 322 nm. Tb3+/Eu3+/Dy3+ triply-doped Zn(PO3)2 glass, excited by AlGaN (322 nm) or InGaN (445 nm) LEDs, could then be appropriated for solid state lighting technology as neutral or warm white light phosphors.

  12. Determination of magnetic anisotropy in the LnTRENSAL complexes (Ln = Tb, Dy, Er) by torque magnetometry.

    PubMed

    Perfetti, Mauro; Lucaccini, Eva; Sorace, Lorenzo; Costes, Jean Pierre; Sessoli, Roberta

    2015-04-01

    We report here a study about the magnetic anisotropy of the LnTRENSAL complexes (Ln = Tb, Dy, Er) performed by using cantilever torque magnetometry and electron paramagnetic resonance. For all of the compounds, we extracted a set of crystal-field parameters to obtain the energy-level splitting of the ground-state multiplet. PMID:25756362

  13. Energy transfer between Ce(3+)  → Gd(3+) or Tb(3+) in KNaSO4 microphosphor.

    PubMed

    Manik, Urvashi; Gedam, S C; Dhoble, S J

    2016-05-01

    KNaSO4 microphosphor doped with Ce,Gd and Ce,Tb and prepared by a wet chemical method was studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) characterization. KNaSO4 has a 5-µm particle size detected by SEM. KNaSO4 :Ce(3+) ,Tb(3+) showed blue and green emission (at 494 nm, 557 nm, 590 nm) of Tb(3+) due to (5) D4  → (7) FJ (J = 4, 5, 6) transitions. KNaSO4 :Ce(3+) ,Gd(3+) showed luminescence in the ultraviolet (UV) light region at 314 nm for an excitation at 271 nm wavelength. It was observed that efficient energy transfer took place from Ce(3+)  → Gd(3+) and Ce(3+)  → Tb(3+) sublattices indicating that Ce(3+) could effectively sensitize Gd(3+) or Tb(3+) (green emission). Ce(3+) emission weakened and Gd(3+) or Tb(3+) enhanced the emission significantly in KNaSO4 . This paper discusses the development and understanding of photoluminescence and the effect of Tb(3+) and Gd(3+) on KNaSO4 :Ce(3+) . Copyright © 2015 John Wiley & Sons, Ltd. PMID:26044916

  14. Static and dynamic magnetic properties and interplay of Dy3+, Gd3+ and Mn3+ spins in orthorhombic DyMnO3 and GdMnO3 nanoparticles

    NASA Astrophysics Data System (ADS)

    Das, Raja; Jaiswal, Adhish; Poddar, Pankaj

    2013-01-01

    Single-phase orthorhombic DyMnO3 and GdMnO3 nanoparticles in the size range 60-70 and 35-45 nm, respectively, were synthesized using a modified hydrothermal method. The magnetic property measurements of DyMnO3 nanocrystals show anomalies around ˜43 K (antiferromagnetic (AFM) coupling between Mn3+ spins) and at 7 K in the form of a peak in the zero-field-cooled curve (AFM coupling between Dy3+ spins). Whereas, GdMnO3 undergoes a phase transition at ˜42 K from paramagnetic to an incommensurate-antiferromagnetic phase (ICAFM) followed by a second anomaly at ˜22 K, which could be associated with the transition from ICAFM into a canted A-type AFM ordering of the Mn3+ spins. This transition is followed by a long-range ordering of the Gd3+ moments at 6 K yielding the canting of the Gd3+ spins with a ferromagnetic (FM) component antiparallel to the FM moment of the canted Mn3+ spins. No anomaly near the Néel temperature of the Mn moments for both DyMnO3 and GdMnO3 nanoparticles was observed in ac magnetization which were observed in dc magnetization. The room temperature Raman spectra of DyMnO3 shows two most intense Raman modes at 480 and 609 cm-1 which can be assigned to an antisymmetric Jahn-Teller stretching mode and a symmetric or breathing stretching mode, respectively, involving Mn-O bond stretching.

  15. Thermodynamic properties of LnBa2Cu3O6 + z (Ln = Gd, Dy, Ho, Yb, and Y) compounds

    NASA Astrophysics Data System (ADS)

    Kovba, M. L.; Voskov, A. L.

    2015-05-01

    Thermodynamic properties of superconductors of LnBa2Cu3O6 + z (Ln = Gd, Dy, Ho, Yb, and Y) are determined by means of EMF using fluoro-ion electrolyte in the temperature range of 900-1250 K. Comparative analyses of the experimental data and thermodynamic models is performed for YBa2Cu3O6 + z compound.

  16. 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.; et al

    2015-05-26

    We combined high field magnetization and magneto-optical spectroscopy to investigate spin-charge coupling in Mn-substituted rare-earth indium oxides of chemical formula RIn₁₋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 5d center.

  17. 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.

  18. Laser-plasma source parameters for Kr, Gd, and Tb ions at 6.6 nm

    SciTech Connect

    Masnavi, Majid; Szilagyi, John; Parchamy, Homaira; Richardson, Martin C.

    2013-04-22

    There is increasing interest in extreme-ultraviolet (EUV) laser-based lamps for sub-10-nm lithography operating in the region of 6.6 nm. A collisional-radiative model is developed as a post-processor of a hydrodynamic code to investigate emission from resonance lines in Kr, Gd, and Tb ions under conditions typical for mass-limited EUV sources. The analysis reveals that maximum conversion efficiencies of Kr occur at 5 Multiplication-Sign 10{sup 10}W/cm{sup 2}, while for Gd and Tb it was Asymptotically-Equal-To 0.9%/2{pi}sr for laser intensities of (2-5) Multiplication-Sign 10{sup 12}W/cm{sup 2}.

  19. Electronic structure and 3d-4f exchange interactions in zircon-type RCrO{sub 4} oxides (R=Dy, Ho and Gd)

    SciTech Connect

    Ray, Avijeet Maitra, Tulika

    2015-06-24

    Using first principles density functional theory (DFT) calculations within GGA and GGA+U approximations we studied both ferromagnetic (FM) and antiferromagnetic (AFM) phases of zircon type RCrO{sub 4} (R= Dy, Ho, Gd) oxides. We estimated and compared the 3d-4f exchange interaction strengths J between the nearest neighbor R{sup 3+} and Cr{sup 5+} ions for R=Dy, Gd. Our results predict that DyCrO{sub 4}, GdCrO{sub 4} and HoCrO{sub 4} have ferromagnetic ground state which is consistent with experimental observations.

  20. 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

  1. Magnetooptics of the luminescent transitions in Tb3+:Gd3Ga5O12

    NASA Astrophysics Data System (ADS)

    Valiev, Uygun V.; Gruber, John B.; Ivanov, Igor'A.; Burdick, Gary W.; Liang, Hongbin; Zhou, Lei; Fu, Dejun; Pelenovich, Oleg V.; Pelenovich, Vasiliy O.; Lin, Zhou

    2015-08-01

    The spectra of the luminescence and magnetic circular polarization of luminescence in terbium-gadolinium gallium garnet Tb3+:Gd3Ga5O12 (Tb3+:GGG) were studied within the visible spectral range at temperatures T = 90 and 300 K in an external magnetic field of 0.45 T. The Zeeman effect in the luminescence "green" band associated with 4f → 4f transition 5D4 → 7F5 of Tb3+:GGG was also studied at T = 90 K in an external field of 0.55 T. Measurement of the Zeeman effect in Tb3+:GGG carried out for some doublet lines of the luminescence band 5D4 → 7F5 at T = 90 K shows that a magnetooptical effect of the intensity change of the emitted light is observed on these lines, in contrast to pure Zeeman splitting of the emission lines measured in the luminescence band 5D4 → 7F6. For the systems we have studied, the maximal value of the magnetooptical effect of the intensity change of the luminescence line at low temperatures has been achieved in paramagnetic garnet Tb0.2Y2.8Al5O12 at comparatively low magnetic fields.

  2. Enhanced photoluminescence of Ba{sub 2}GdNbO{sub 6}: Eu{sup 3+}/Dy{sup 3+} phosphors by Li{sup +} doping

    SciTech Connect

    Yu, C.C.; Liu, X.M.; Yu, M.; Lin, C.K.; Li, C.X.; Wang, H.; Lin, J.

    2007-11-15

    The Ba{sub 2}GdNbO{sub 6}: Eu{sup 3+}/Dy{sup 3+} and Li{sup +}-doped Ba{sub 2}GdNbO{sub 6}: Eu{sup 3+}/Dy{sup 3+} phosphors were prepared by solid-state reaction process. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and photoluminescence (PL) as well as lifetimes, was utilized to characterize the resulting phosphors. Under the excitation of ultraviolet light, the Ba{sub 2}GdNbO{sub 6}: Eu{sup 3+}/Dy{sup 3+} and Li{sup +}-doped Ba{sub 2}GdNbO{sub 6}: Eu{sup 3+}/Dy{sup 3+} show the characteristic emissions of Eu{sup 3+} ({sup 5}D{sub 0}-{sup 7}F{sub 1,2,3} transitions dominated by {sup 5}D{sub 0}-{sup 7}F{sub 1} at 593 nm) and Dy{sup 3+} ({sup 4}F{sub 9/2}-{sup 6}H{sub 15/2},{sub 13/2} transitions dominated by {sup 4}F{sub 9/2}-{sup 6}H{sub 15/2} at 494 nm), respectively. The incorporation of Li{sup +} ions into the Ba{sub 2}GdNbO{sub 6}: Eu{sup 3+}/Dy{sup 3+} phosphors has enhanced the PL intensities depending on the doping concentration of Li{sup +}, and the highest emission was obtained in Ba{sub 2}Gd{sub 0.9}NbO{sub 6}: 0.10Eu{sup 3+}, 0.01Li{sup +} and Ba{sub 2}Gd{sub 0.95}NbO{sub 6}: 0.05Dy{sup 3+}, 0.07Li{sup +}, respectively. An energy level diagram was proposed to explain the luminescence process in the phosphors. - Graphical abstract: The Ba{sub 2}GdNbO{sub 6}: Eu{sup 3+}/Dy{sup 3+} and Li{sup +}-doped Ba{sub 2}GdNbO{sub 6}: Eu{sup 3+}/Dy{sup 3+} phosphors were prepared by solid-state reaction. The incorporation of Li{sup +} ions into the Ba{sub 2}GdNbO{sub 6}: Eu{sup 3+}/Dy{sup 3+} phosphors has enhanced the photoluminescence intensities of Eu{sup 3+} and Dy{sup 3+}, depending on the doping concentration of Li{sup +}.

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

    NASA Astrophysics Data System (ADS)

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

    2007-10-01

    Dy161,163(t,α) 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.

  4. Size-dependent magnetic ordering and spin-dynamics in DyPO4 and GdPO4 nanoparticles

    SciTech Connect

    Evangelisti, Marco; Sorop, Tibi G; Bakharev, Oleg N; Visser, Dirk; Hillier, Adrian D.; Alonso, Juan; Haase, Markus; Boatner, Lynn A; De Jongh, L. Jos

    2011-01-01

    Low-temperature magnetic susceptibility and heat capacity measurements on nanoparticles (d 2.6 nm) of the antiferromagnetic compounds DyPO4 (TN = 3:4 K) and GdPO4 (TN = 0:77 K) provide clear demonstrations of finite-size effects, which limit the divergence of the magnetic correlation lengths, thereby suppressing the bulk long-range magnetic ordering transitions. Instead, the incomplete antiferromagnetic order inside the particles leads to the formation of net magnetic moments on the particles. For the nanoparticles of Ising-type DyPO4 superparamagnetic blocking is found in the ac-susceptibility at 1 K, those of the XY-type GdPO4 analogue show a dipolar spin-glass transition at 0:2 K. Monte Carlo simulations for the magnetic heat capacities of both bulk and nanoparticle samples are in agreement with the experimental data. Strong size effects are also apparent in the Dy3+ and Gd3+ spin-dynamics, which were studied by zero-field SR relaxation and high-field 31P-NMR nuclear relaxation measurements. The freezing transitions observed in the ac-susceptibility of the nanoparticles also appear as peaks in the temperature dependence of the zero-field SR rates, but at slightly higher temperatures - as to be expected from the higher frequency of the muon probe. For both bulk and nanoparticles of GdPO4, the muon and 31P-NMR rates are for T 5 K dominated by exchange-narrowed hyperfine broadening arising from the electron spin-spin interactions inside the particles. The dipolar hyperfine interactions acting on the muons and the 31P are, however, much reduced in the nanoparticles. For the DyPO4 analogues the high-temperature rates appear to be fully determined by electron spin-lattice relaxation processes.

  5. Multiple charge density wave transitions in the antiferromagnets R NiC2 (R =Gd ,Tb)

    NASA Astrophysics Data System (ADS)

    Shimomura, S.; Hayashi, C.; Hanasaki, N.; Ohnuma, K.; Kobayashi, Y.; Nakao, H.; Mizumaki, M.; Onodera, H.

    2016-04-01

    X-ray scattering and electrical resistivity measurements were performed on GdNiC2 and TbNiC2. We found a set of satellite peaks characterized by q1=(0.5 ,η ,0 ) below T1, at which the resistivity shows a sharp inflection, suggesting the charge density wave (CDW) formation. The value of η decreases with decreasing temperature below T1, and then a transition to a commensurate phase with q1 C=(0.5 ,0.5 ,0 ) takes place. The diffuse scattering observed above T1 indicates the presence of soft phonon modes associated with CDW instabilities at q1 and q2=(0.5 ,0.5 ,0.5 ) . The long-range order given by q2 is developed in addition to that given by q1 C in TbNiC2, while the short-range correlation with q2 persists even at 6 K in GdNiC2. The amplitude of the q1 C lattice modulation is anomalously reduced below an antiferromagnetic transition temperature TN in GdNiC2. In contrast, the q2 order vanishes below TN in TbNiC2. We demonstrate that R NiC2 (R = rare earth) compounds exhibit similarities with respect to their CDW phenomena, and discuss the effects of magnetic transitions on CDWs. We offer a possible displacement pattern of the modulated structure characterized by q1 C and q2 in terms of frustration.

  6. NMR evidence of a long exchange lifetime for the coordinated water in Ln(III)-bis(methyl amide)-DTPA complexes (Ln = Gd, Dy)

    SciTech Connect

    Aime, S.; Botta, M.; Fasano, M.

    1994-10-12

    The water proton longitudinal relaxation rate for Gd-BMA-DTPA was studied at various temperatures and under varied magnetic fields. It was found that a correlation exists between the residence lifetime {tau}{sub M} of the coordinated water molecule in the coordination site on the metal chelate. The Gd(III) result was confirmed by related studies for Dy(III).

  7. Mssbauer 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, Mssbauer 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 17107 ? cm, 162107 ? cm, 171107 ? cm and 305107 ? cm respectively. The AC resistivity values (at 1 KHz) of NiFe2O4, NiFe1.925Sm0.075O4, NiFe1.925Gd0.075O4 and NiFe1.925Dy0.075O4 materials are 10105 ? cm, 77105 ? cm, 147105 ? cm and 251105 ? 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.

  8. 3- and 4-(α-diazobenzyl)pyridine-N-oxides as photoresponsive magnetic couplers for 2p-4f heterospin systems: formation of carbene-Tb(III) and carbene-Dy(III) single-molecule magnets.

    PubMed

    Murashima, Kensuke; Karasawa, Satoru; Yoza, Kenji; Inagaki, Yuji; Koga, Noboru

    2016-04-19

    3- and 4-(α-diazophenyl)pyridine-N-oxides, and , were prepared as new photoresponsive magnetic couplers in heterospin systems. Lanthanide dinuclear complexes, [Ln(III)(tta)3()]2; Ln(III) = Gd (), Tb (), and Dy () and tta = 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionate, bridged with in μ2 coordination mode were obtained. The obtained , , and were isostructures. The isomeric complex, [Tb(III)(tta)3()]2 was also prepared. In the carbene-Ln(III) complexes [Ln(III)(tta)3( and )]2 generated by photolysis, regioselectively interacted with the Ln(III) ions through pyridine-N-oxide, in which the magnetic coupling of was weakly ferromagnetic, while that of was insignificant. Before and after irradiation of , no SMM behavior was observed. In contrast, the Tb(III) and Dy(III) complexes being anisotropic functioned as heterospin SMMs. Before irradiation, showed no SMM behavior. After irradiation, two species showing slow magnetic relaxations were produced and one of them exhibited SMM behavior with the thermal activation barrier, Ueff/kB = 30 K, and τ0 = 5.8 × 10(-8) s. In , SMM behaviors were observed before and after irradiation, and the Ueff/kB value of 102 K (τ0 = 3.6 × 10(-7) s) before irradiation was reduced to 39 K (τ0 = 1.5 × 10(-8) s) after irradiation. PMID:27003316

  9. 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; Key Lab of Coherent Light, Atomic and Molecular Spectroscopy, Ministry of Education, Changchun 130012 ; Fu, Zuoling; Key Lab of Coherent Light, Atomic and Molecular Spectroscopy, Ministry of Education, Changchun 130012 ; Zhou, Shihong; Zhang, Siyuan; Jeong, Jung Hyun

    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).

  10. Low-temperature anomaly of the magnetization in alloys (Pr,Dy, M)2(Fe,Co)14B ( M = Gd, Sm, Nd)

    NASA Astrophysics Data System (ADS)

    Kablov, E. N.; Ospennikova, O. G.; Rezchikova, I. I.; Valeev, R. A.; Cherednichenko, I. V.; Kunitsyna, E. I.; Morgunov, R. B.; Piskorskii, V. P.

    2016-03-01

    It has been found that temperature dependences of the saturation magnetization of sintered hard magnetic (Pr,Dy, M)2(Fe,Co)14B ( M = Gd, Sm, Nd) alloys demonstrate an increase at a temperature lower than a critical temperature (150 K for Sm and Nd and 70 K for Gd). An additive of copper does not influence the critical temperature. It has been assumed that there is a low-temperature phase in which cobalt is replaced with boron that diffuses from the (Pr,Dy,Gd)(Fe,Co)4B phase to the near-surface region of grains of the main magnetic (Pr,Dy,Gd)2(Fe,Co)14B phase.

  11. Phase transformations and indications for acoustic mode softening in Tb-Gd orthophosphate

    NASA Astrophysics Data System (ADS)

    Tschauner, O.; Ushakov, S. V.; Navrotsky, A.; Boatner, L. A.

    2016-01-01

    At ambient conditions the anhydrous rare earth orthophosphates assume either the xenotime (zircon) or the monazite structure, with the latter favored for the heavier rare earths and by increasing pressure. Tb0.5Gd0.5PO4 assumes the xenotime structure at ambient conditions but is at the border between the xenotime and monazite structures. Here we show that, at high pressure, Tb0.5Gd0.5PO4 does not transform directly to monazite but through an intermediate anhydrite-type structure. Axial deformation of the unit cell near the anhydrite- to monazite-type transition indicates softening of the (c1133  +  c1313) combined elastic moduli. Stress response of rare-earth orthophosphate ceramics can be affected by both formation of the anhydrite-type phase and the elastic softening in the vicinity of the monazite-phase. We report the first structural data for an anhydrite-type rare earth orthophosphate.

  12. Phase transformations and indications for acoustic mode softening in Tb-Gd orthophosphate.

    PubMed

    Tschauner, O; Ushakov, S V; Navrotsky, A; Boatner, L A

    2016-01-27

    At ambient conditions the anhydrous rare earth orthophosphates assume either the xenotime (zircon) or the monazite structure, with the latter favored for the heavier rare earths and by increasing pressure. Tb0.5Gd0.5PO4 assumes the xenotime structure at ambient conditions but is at the border between the xenotime and monazite structures. Here we show that, at high pressure, Tb0.5Gd0.5PO4 does not transform directly to monazite but through an intermediate anhydrite-type structure. Axial deformation of the unit cell near the anhydrite- to monazite-type transition indicates softening of the (c1133  +  c1313) combined elastic moduli. Stress response of rare-earth orthophosphate ceramics can be affected by both formation of the anhydrite-type phase and the elastic softening in the vicinity of the monazite-phase. We report the first structural data for an anhydrite-type rare earth orthophosphate. PMID:26733233

  13. White light emitting LaGdSiO5:Dy3+ nanophosphors for solid state lighting applications

    NASA Astrophysics Data System (ADS)

    Ogugua, Simon N.; Swart, Hendrik C.; Ntwaeaborwa, Odireleng M.

    2016-01-01

    Powdered dysprosium (Dy3+) doped Lanthanum gadolinium oxyorthosilicate (LaGdSiO5) mixed phosphors were synthesized using urea-assisted solution combustion method. The X-ray diffractometer analysis showed that the samples crystalized in the pure monoclinic mixed phase of LaGdSiO5. The crystallite size and the lattice strain calculated from the X-ray diffraction peaks using Williamson-Hall equation varied from 12 nm to 16 nm and 1.6 ×10-2 to 2.43 ×10-2 respectively. The photoluminescence (PL) emission spectra recorded using 425, 454 and 475 nm excitation wavelengths exhibit characteristic similar to the YAG:Ce phosphor pumped InGaN LED system, by absorbing portion of the excitation energy and re-emitting it. The emission spectra were characterized by radiative recombination at 425, 454, 475, 485 and 575 nm depending on the excitation wavelength. These emission line are ascribed to the f→f transitions of Dy3+. The peak intensity and hence the color of the emitted visible light were dependent on the concentration of Dy3+. The International Commission on Illumination (CIE) color coordinates of (0.336, 0.313) and (0.359, 0.361) were obtained for Dy3+ molar concentration of 0.05 and 3.0 mol% when the emission was monitored using 454 nm and 475 nm respectively. The band gap measured from the reflectance curve using Tauc plot initially decreased with increasing Dy3+ concentration, but at higher concentration, it started to increase. These materials were evaluated for solid state lighting application.

  14. Synthesis and photoluminescence properties of Ln3+ (Ln3+=Tb3+, Dy3+, Sm3+, Er3+)-doped Ca2Nb2O7 phosphors

    NASA Astrophysics Data System (ADS)

    Xian, Jieqiang; Yi, Shuangping; Deng, Yaomin; Zhang, Lu; Hu, Xiaoxue; Wang, Yinhai

    2016-02-01

    A series of Ln3+ (Ln3+=Tb3+/Dy3+/Sm3+/Er3+) ions doped Ca2Nb2O7 phosphors have been synthesized by high-temperature solid-state reaction. The Ln3+-doped samples are well indexed to the pure Ca2Nb2O7 phase which revealed for the X-ray diffraction (XRD) result. Under the ultraviolet light, the prepared Ca2-xNb2O7:xLn3+ (Ln3+=Tb3+/Dy3+/Sm3+/Er3+) phosphors show the characteristic cyan (Tb3+), green-white (Sm3+), yellowish (Dy3+) and green (Er3+) emissions. The energy transfer mechanisms in Ca2Nb2O7: Tb3+/Dy3+/Sm3+/Er3+ phosphors have been investigated and it deduced to be a resonant type via an electric dipole-dipole interaction. In addition, their critical distances have been calculated by concentration quenching methods. The luminescence properties of Ca2Nb2O7:Tb3+/Dy3+/Sm3+/Er3+ phosphors indicated that the Ca2Nb2O7 is a suitable host for rare earth doped laser crystal and optical materials.

  15. Luminescence studies of Sm3+ single-doped and Sm3+, Dy3+ co-doped NaGdTiO4 phosphors

    NASA Astrophysics Data System (ADS)

    Li, Xiangping; Wang, Xin; Li, Xuejing; Cheng, Lihong; Tong, Lili; Wang, Wenlong; Sun, Jiashi; Zhang, Jinsu; Chen, Baojiu

    2016-01-01

    Sm3+ single-doped and Sm3+, Dy3+ co-doped NaGdTiO4 phosphors were synthesized via a traditional high temperature solid-state reaction method. The crystal structure was characterized by means of x-ray diffraction. The luminescence properties and energy transfer in Sm3+ single-doped and Sm3+, Dy3+ co-doped NaGdTiO4 phosphors were systematically studied. The electric dipole-dipole interaction between Sm3+ ions was identified as the main mechanism for the concentration dependent fluorescence quenching in Sm3+ single-doped samples. It is confirmed that there is almost no energy transfer between Sm3+ and Dy3+ in Sm3+, Dy3+ co-doped samples. The introduction of Sm3+ can compensate the red emission component and adjust the colorimetric performance of Dy3+-doped NaGdTiO4 phosphors. Moreover, different emitting colors can be obtained from Sm3+, Dy3+ co-doped NaGdTiO4 phosphor by changing the excitation pathway.

  16. 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

  17. Robust tunability of magnetoresistance in half-Heusler R PtBi (R =Gd , Dy, Tm, and Lu) compounds

    NASA Astrophysics Data System (ADS)

    Mun, Eundeok; Bud'ko, Sergey L.; Canfield, Paul C.

    2016-03-01

    We present the magnetic field dependencies of transport properties for R PtBi (R =Gd , Dy, Tm, and Lu) half-Heusler compounds. Temperature- and field-dependent resistivity measurements of high-quality R PtBi single crystals reveal an unusually large, nonsaturating magnetoresistance (MR) up to 300 K under a moderate magnetic field of H =140 kOe. At 300 K, the large MR effect decreases as the rare earth is traversed from Gd to Lu and the magnetic field dependence of MR shows a deviation from the conventional H2 behavior. The Hall coefficient (RH) for R =Gd indicates a sign change around 120 K, whereas RH curves for R =Dy , Tm, and Lu remain positive for all measured temperatures. At 300 K, the Hall resistivity reveals a deviation from the linear field dependence for all compounds. Thermoelectric power measurements on this family show strong temperature and magnetic field dependencies which are consistent with resistivity measurements. A highly enhanced thermoelectric power under applied magnetic field is observed as high as ˜100 μ V /K at 140 kOe. Analysis of the transport data in this series reveals that the rare-earth-based half-Heusler compounds provide opportunities to tune MR effect through lanthanide contraction and to elucidate the mechanism of nontrivial MR.

  18. Experimental and theoretical study of mechanoluminescence and lyoluminescence of Li3 PO4 : RE (RE = Dy and Tb) phosphors.

    PubMed

    Sahu, A K; Kadukar, Monali R; Chowdhary, P S; Nayar, V; Dhoble, S J

    2014-12-01

    Li3 PO4 phosphors prepared by solid-state diffusion technique and lyoluminescence (LL) as well as mechanoluminescence (ML) studies are reported. Dy- and Tb-activated phosphors show dosimetric characteristics using LL and ML techniques. The energy levels and hence trapping and detrapping of charge carriers in the material can be studied using ML. Li3 PO4 phosphor can be used in the dosimetric applications for ionizing radiation. By using the LL technique, the LL characteristics of Li3 PO4 may be useful for high radiation doses. We also report a more detailed theoretical understanding of the mechanism of LL and ML. PMID:24760580

  19. 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.

  20. Spin structure and magnetic frustration in multiferroic RMn{sub 2}O{sub 5} (R=Tb,Ho,Dy)

    SciTech Connect

    Blake, G.R.; Chapon, L.C.; Radaelli, P.G.; Park, S.; Hur, N.; Cheong, S-W.; Rodriguez-Carvajal, J.

    2005-06-01

    We have studied the crystal and magnetic structures of the magnetoelectric materials RMn{sub 2}O{sub 5} (R=Tb,Ho,Dy) using neutron diffraction as a function of temperature. All three materials display incommensurate antiferromagnetic ordering below 40 K, becoming commensurate on further cooling. For R=Tb,Ho, a commensurate-incommensurate transition takes place at low temperatures. The commensurate magnetic structures have been solved and are discussed in terms of competing exchange interactions. The spin configuration within the ab plane is essentially the same for each system, and the radius of R determines the sign of the magnetic exchange between adjacent planes. The inherent magnetic frustration in these materials is lifted by a small lattice distortion, primarily involving shifts of the Mn{sup 3+} cations and giving rise to a canted antiferroelectric phase.

  1. Photoluminescent properties of Tb3+ doped GdSrAl3O7 nanophosphor using solution combustions synthesis

    NASA Astrophysics Data System (ADS)

    Khatkar, Satyender Pal; Singh, Sonika; Lohra, Sheetal; Khatkar, Avni; Taxak, Vinod

    2015-05-01

    A color tunable terbium doped GdSrAl3O7 nanophosphor has been synthesized at low temperature using solution combustion synthesis. The photoluminescent properties of nanophosphors have been explored by analyzing their excitation and emission spectra alongwith their decay curves. The emission spectra exhibit dominating green light at 544 nm due to 5D4?7F5 transition of Tb3+ ions in GdSrAl3O7 on excitation by UV light of 239 nm. Furthermore, the luminescence in Gd( 1- x)SrAl3O7: xTb3+nanophosphors shifted from blue to green color by properly tuning the concentration of terbium ions. Decay curves indicate that non-radiative cross-relaxation is primarily responsible for concentration quenching phenomenon in the GdSrAl3O7 host. X-ray diffraction (XRD) analysis confirmed that single tetragonal phased nanophosphor could be readily obtained at low temperature 550C. The smooth surfaced nanocrystals with particle size of 45 - 50 nm have also been examined by transmission electron microscopy (TEM). All these features augmented the probability of GdSrAl3O7: Tb3+ nanophosphor for potential applications in optical devices. [Figure not available: see fulltext.

  2. Perpendicular magnetic anisotropy and magnetostriction of evaporated Co-(Pr,Nd,Gd,Dy,Er) amorphous binary alloy films

    SciTech Connect

    Takahashi, M.; Yoshihara, A.; Shimamori, T.; Miyazki, T.; Wakiyama, T. )

    1988-06-01

    The authors have been trying to clarify the origin of perpendicular magnetic anisotropy (K{sub perpendicular}) of amorphous rare earth-transition metal ally films, by means of changing the kind of rare earths and their composition systematically for Fe or Co based binary systems. In this study, they used Gd, Dy, and Er as the rare earth elements, and investigated the temperature dependence of K{sub perpendicular} and the saturation magnetization M{sub s}, as well as the film magnetostriction.

  3. Combustion synthesis of SrAl4O7:Eu2+, Dy3+, Gd3+ long lasting phosphor

    NASA Astrophysics Data System (ADS)

    Yerpude, A. N.; Dhoble, S. J.

    2015-02-01

    Long afterglow strontium aluminates SrAl4O7:Eu2+,Dy3+,Gd3+ phosphor was prepared by combustion method. The X-ray diffraction (XRD), Scanning electron microscope (SEM) and photoluminescence (PL) spectrum as well as the luminescence decay were used to characterize the long lasting phosphor. The emission spectrum of the phosphor shows broadened band at 495 nm assigned to the 4f65d→4f7(8S7/2) transition of Eu2+. The present phosphor shows green persistent luminescence after removal of the UV light.

  4. Magnetic circular dichroism in 5p photoemission from Gd and Tb metal

    SciTech Connect

    van der Laan, G.; Arenholz, E.; Navas, E.; Hu, Z.; Mentz, E.; Bauer, A.; Kaindl, G.

    1997-08-01

    The isotropic and magnetic-circular-dichroism (MCD) 5p core-level photoemission (PE) spectra of Gd(0001) and Tb(0001) are presented. Large MCD effects were observed at the low-binding-energy side, gradually reducing in amplitude at higher binding energies. Both the isotropic and the MCD-PE spectra can be well reproduced by a many-particle intermediate-coupling approach taking spin-orbit, Coulomb, and exchange interactions properly into account. We also present a simple model to understand the global line shape of the MCD spectra. The MCD permits an accurate determination of the values of the Coulomb and exchange interactions in the final state. {copyright} {ital 1997} {ital The American Physical Society}

  5. μSR study of RNi5 intermetallics where R=La, Gd or Tb

    NASA Astrophysics Data System (ADS)

    Dalmas de Réotier, P.; Sanchez, J. P.; Yaouanc, A.; Harris, S. W.; Hartmann, O.; Karlsson, E.; Wäppling, R.; Gignoux, D.; Gorges, B.; Schmitt, D.; L'Héritier, Ph.; Weidinger, A.; Gubbens, P. C. M.

    1991-02-01

    Zero-field μSR studies of some hexagonal intermetallic compounds are described. Our LaNI5 data provide information on the muon localisation site. This site could be one of the deuterium sites deduced from neutron diffraction. A comparison of the temperature dependence of the exponential damping rate, λ( T), of our samples shows that λ( T) is strongly influenced by crystal field effects. The TbNi5 spectra exhibit two components for T<60 K. We discuss the possible explanations of this result. We see a μSR signal below the magnetic phase transition in GdNi5. This makes the study of the spin-lattice relaxation rate possible in the ordered magnetic state.

  6. 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; Shi, Youguo; Kang, Bin; Deng, Jianguo; Yao, Jiyong; Wu, Yicheng

    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.

  7. The influence of Dy additions on the magnetocaloric effect in Gd{sub 0.97}V{sub 0.03} alloys

    SciTech Connect

    Feng Zai Wu Wei; Zhao Hui; Yin Guangfu

    2009-04-15

    The influence of Dy on the magnetocaloric effect in Gd{sub 0.97-x}Dy{sub x}V{sub 0.03} (x = 0.1, 0.2, 0.3) alloys has been studied. These alloys were prepared by arc melting on a water-cooled copper hearth under an argon atmosphere. The magnetization behavior has been analyzed by X-ray diffraction and a vibrating sample magnetometer. Results indicate that the Curie points of Gd{sub 0.97-x}Dy{sub x}V{sub 0.03} alloys decrease linearly with increasing content of Dy. The values of maximum magnetic entropy change ({delta}S{sub M}) and relative cooling power (RCP) for x = 0 {approx} 0.2 is larger than that of Gd alone over a wider temperature range. The Gd{sub 0.97-x}Dy{sub x}V{sub 0.03} alloys have promising potential as working substance candidates for magnetic refrigeration due to their tunable Curie temperature and the favorable properties of the magnetocaloric effect.

  8. Magnetism and crystal chemistry in REFe12 - xGax (RE=Y,Ce,Pr,Nd,Sm,Gd,Tb,Dy,Ho,Er,Tm,Yb,Lu and MM=mischmetal) and (Zr,Pr) (Fe1 - xCox)12 - yGay

    NASA Astrophysics Data System (ADS)

    Weitzer, F.; Hiebl, K.; Rogl, P.; Grin, Yu. N.

    1990-10-01

    The existence of ternary compounds according to the formula REFe12-x Gax which for x ˜6 represents the iron-rich end of a homogeneous range has been confirmed. X-ray powder analysis of alloys annealed at 800 °C or above generally reveal isotypism with the body- centered tetragonal ThMn12 -type structure. For the alloys with heavier rare-earth elements from Gd to Lu a phase transition to a body-centered orthorhombic structure type (ScFe6 Ga6 type) is observed, which has not been reported before. The transition corresponds to a crystallographic group-subgroup relation (I4/mmm→t2 →Immm), and the transition temperature increases with the ordinal number of the rare earth, indicating the higher the stability of the ScFe6 Ga6 -type structure, the smaller the radius of the rare-earth element. Accordingly, the ThMn12 -type structure is stable for the early rare-earth members and no transition was observed as low as 400 °C. From magnetization curves it is shown that for REFe12-x Gax (RE=rare earth, Y) all magnetic sublattices order simultaneously at temperatures above Tc ˜400 K. For Y, Lu, and light rare-earth-containing alloys collinear or canted ferromagnetism is observed. The vector of magnetization was found to be close to the a,b plane. Strong hysteresis effects are revealed in all alloys. Energy products are highest for (Pr,Sm)Fe˜6Ga˜6. For the compounds with the heavy rare-earth elements a ferrimagnetic behavior is encountered. Both magnetic sublattices, i.e., Fe and RE, couple antiparallel, exhibiting easy plane anisotropy. The crystallographic transformation, tetragonal-orthorhombic, has little effect on the magnetic behavior of these alloys. (Zr,Hf)(Fe1-x Cox )12-y Gay remain temperature-independent paramagnets.

  9. 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. Karimov, D. N.; Sul'yanov, S. N.; Zhmurova, Z. I.

    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.

  10. Superconductivity and magnetism in Chevrel-phase rare-earth molybdenum selenides single crystals REMo 6Se 8 (RE = Gd, Dy).

    NASA Astrophysics Data System (ADS)

    Peña, O.; LeBerre, F.; Sergent, M.; Horyń, R.; Wojakowski, A.

    1994-12-01

    Chevrel phases containing rare-earth atoms (REMo 6X 8; X = S, Se) are model systems which can present at the same time, phenomena of superconductivity and long-range magnetic interactions. We have recently developed a new crystal growth method specific to the selenides series, which was applied to RE = Gd, Dy, Ho, Er and Yb. We present results obtained on single crystals of GdMo 6Se 8 and DyMo 6Se 8. A discussion of the crystal growth method and of the ternary phase relations is done, and results are compared to those obtained for the binary isostructural compound Mo 3Se 4.

  11. Orientation Selection and Microstructural Evolution in Directionally Solidified Tb0.3Dy0.7Fe1.95

    NASA Astrophysics Data System (ADS)

    Palit, Mithun; Banumathy, S.; Singh, A. K.; Pandian, S.; Chattopadhyay, Kamanio

    2016-04-01

    Tb0.3Dy0.7Fe1.95 alloy was directionally solidified by using a modified Bridgman technique at a wide range of growth rates of 5 to 100 cm/h. The directionally grown samples exhibited plane front solidification morphology up to a growth rate of 90 cm/h. Typical island banding feature was observed closer to the chilled end, which eventually gave rise to irregular peritectic coupled growth (PCG). The PCG gained prominence with an increase in the growth rate. The texture study revealed formation of strong <311> texture in a lower growth rate regime, <110> and "rotated <110>" in an intermediate growth regime, and <112> in a higher growth rate regime. In-depth analysis of the atomic configuration of a solid-liquid interface revealed that the growth texture is influenced by the kinetics of atomic attachment to the solid-liquid interface, which is intimately related to a planar packing fraction and an atomic stacking sequence of the interfacial plane. The mechanism proposed in this article is novel and will be useful in addressing the orientation selection mechanism of topologically closed packed intermetallic systems. The samples grown at a higher growth rate exhibit larger magnetostriction ( λ) and dλ/dH owing to the absence of pro-peritectic (Tb,Dy)Fe3 and formation of <112> texture, which lies closer to the easy magnetization direction (EMD).

  12. RNi8Si3 (R=Gd,Tb): Novel ternary ordered derivatives of the BaCd11 type

    NASA Astrophysics Data System (ADS)

    Pani, M.; Morozkin, A. V.; Yapaskurt, V. O.; Provino, A.; Manfrinetti, P.; Nirmala, R.; Malik, S. K.

    2016-01-01

    The title compounds have been synthesized and characterized both from the structural and magnetic point of view. Both crystallize in a new monoclinic structure strictly related to the tetragonal BaCd11 type. The structure was solved by means of X-ray single-crystal techniques for GdNi8Si3 and confirmed for TbNi8Si3 on powder data; the corresponding lattice parameters (obtained from Guinier powder patterns) are a=6.3259(2), b=13.7245(5), c=7.4949(3) Å, β=113.522(3)°, Vcell=596.64(3) Å3 and a=6.3200(2), b=13.6987(4), c=7.4923(2) Å, β=113.494(2)°, Vcell=594.88(2) Å3. The symmetry relationship between the tI48-I41/amd BaCd11 aristotype and the new ordered mS48-C2/c GdNi8Si3 derivative is described via the Bärnighausen formalism within the group theory. The large Gd-Gd (Tb-Tb) distances, mediated via Ni-Si network, likely lead to weak magnetic interactions. Low-field magnetization vs temperature measurements indicate weak and field-sensitive antiferromagnetic ground state, with ordering temperatures of 3 K in GdNi8Si3 and about 2-3 K in TbNi8Si3. On the other hand, the isothermal field-dependent magnetization data show the presence of competing interactions in both compounds, with a field-induced ferromagnetic behavior for GdNi8Si3 and a ferrimagnetic-like behavior in TbNi8Si3 at the ordering temperature TC/N of about (or slightly higher than) 3K. The magnetocaloric effect, quantified in terms of isothermal magnetic entropy change ΔSm, has the maximum values of -19.8 J(kg K)-1 (at 4 K for 140 kOe field change) and -12.1 J(kg K)-1 (at 12 K for 140 kOe field change) in GdNi8Si3 and TbNi8Si3, respectively.

  13. Soft-chemical synthesis and tunable luminescence of Tb3+, Tm3+/Dy(3+)-doped SrY2O4 phosphors for field emission displays.

    PubMed

    Zhang, Yang; Geng, Dongling; Shang, Mengmeng; Zhang, Xiao; Li, Xuejiao; Cheng, Ziyong; Lian, Hongzhou; Lin, Jun

    2013-04-14

    Tb(3+), Tm(3+), and Dy(3+)-activated SrY2O4 phosphors have been prepared via Pechini-type sol-gel method. X-Ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL) and lifetimes, as well as cathodoluminescence (CL) spectra were used to characterize the samples. Under low-voltage electron beam excitation, the Tb(3+)-doped samples show a green luminescence, with a better CIE coordinates and higher emission intensity than the commercial product ZnO: Zn. Blue and yellow emissions could be obtained by doping with Tm(3+) and Dy(3+), respectively. A color-tunable emission in SrY2O4 phosphors can be realized by co-doping with Tm(3+) and Dy(3+). White cathodoluminescence (CL) has been realized in a single-phase SrY2O4 host by co-doping with Tm(3+) and Dy(3+) for the first time with CIE (0.315, 0.333). Furthermore, the cathodoluminescence (CL) properties of SrY2O4: Tb(3+)/Tm(3+)/Dy(3+) phosphors including the dependence of CL intensity on accelerating voltage and filament current, the decay behaviour of CL intensity under electron bombardment, and the stability of CIE chromaticity coordinate have been investigated in detail. The as-prepared phosphors might be promising for use in field-emission display (FED) devices. PMID:23299830

  14. Heteronuclear Ni(ii)-Ln(iii) (Ln = La, Pr, Tb, Dy) complexes: synthesis and single-molecule magnet behaviour.

    PubMed

    Upadhyay, Apoorva; Das, Chinmoy; Langley, Stuart K; Murray, Keith S; Srivastava, Anant K; Shanmugam, Maheswaran

    2016-02-16

    The reaction of hydrated nickel(ii) salts (chloride or nitrate) and hydrated lanthanide nitrate salts with the Schiff base ligand 2-methoxy-6-[(E)-phenyliminomethyl] phenol (HL) in methanol resulted in the isolation of three isostructural linear heterometallic trinuclear complexes and a heterometallic tetranuclear complex. The molecular structures of these complexes were determined via single crystal X-ray diffraction revealing molecular structures of formulae [Ni2La(L(-))6](NO3)0.55(OH)0.45 (), [Ni2Pr(L(-))6](NO3)0.48(OH)0.52 (), [Ni2Tb(L(-))6](NO3)0.5(Cl)0.5 () and [Ni2Dy2(L(-))2(o-vanillin)2(CO3)2(NO3)2(MeOH)2] (). Structural analysis for reveals that the lanthanide ion is sandwiched between two Ni(ii) ions and the NiLnNi metallic core displays a linear arrangement, with an average ∠NiLnNi bond angle of 179.7°. Analysis of reveals the metal ions are arranged such that two Ni-Dy subunits are bridged by two carbonate ligands via the Dy sites. Direct current magnetic susceptibility measurements for complexes reveal that the Ni(ii) ions are coupled ferromagnetically with the Tb(iii) () and Dy(iii) () ions, and antiferromagnetically with the Pr(iii) ion (). For complex a long range intramolecular ferromagnetic interaction is witnessed between the Ni(ii) ions (NiNi = 6.873(9) Å) via a closed shell La(iii) ion. The magnetic data of were fitted using the HDVV Hamiltonian revealing the following parameters; J = +0.46 cm(-1), g = 2.245, D = +4.91 cm(-1). Alternating current magnetic susceptibility measurements performed on complexes revealed that and displayed frequency dependent χ''M signals (Hac = 3.5 Oe and Hdc = 0 Oe) which is a characteristic signature of a single-molecule magnet behaviour. PMID:26810917

  15. The structure, magnetostriction, and hysteresis of (Tb0.3Dy0.7Fe1.9)1-x(Tb0.15Ho0.85Fe1.9)x alloys

    NASA Astrophysics Data System (ADS)

    Wang, Bowen; Lv, Yan; Li, Guolu; Huang, Wenmei; Weng, Ling; Cui, Baozhi

    2015-05-01

    The (Tb0.3Dy0.7Fe1.9)1-x(Tb0.15Ho0.85Fe1.9)x alloys were prepared in an arc furnace under high purity argon. The as-cast samples wrapped in Mo foil were sealed in a silica tube filled with high purity argon and were homogenized at 1000 °C for 1 day and at 950 °C for 5 days. Then, the homogenized specimens with 5 mm in diameter and 8 mm in length were annealed under the magnetic field of 320 kA/m. The static measurement of magnetostriction (λ//, λ⊥) was made by standard strain gauge, and the magnetization M was measured by a vibrating sample magnetometer. It is found that the main phase of annealed (Tb0.3Dy0.7Fe1.9)1-x(Tb0.15Ho0.85Fe1.9)x alloys is the (Tb,Dy,Ho)Fe2 phase with the MgCu2-type structure. The magnetostriction λ// and magnetization M of (Tb0.3Dy0.7Fe1.9)1-x(Tb0.15Ho0.85Fe1.9)x alloys increases with increasing x from x = 0.1 to x = 0.3 when H < 240 kA/m. The hysteresis becomes small with increasing x when x ≤ 0.3. For magnetically annealed rod alloys, the magnetostriction markedly increases and reaches 1080 × 10-6 for x = 0.3 when H = 240 kA/m.

  16. Two isostructural 3D lanthanide coordination networks (Ln = Gd(3+), Dy(3+)) with squashed cuboid-type nanoscopic cages showing significant cryogenic magnetic refrigeration and slow magnetic relaxation.

    PubMed

    Biswas, Soumava; Jena, Himanshu Sekhar; Adhikary, Amit; Konar, Sanjit

    2014-04-21

    Two isostructural lanthanide-based 3D coordination networks [Ln = Gd(3+) (1), Dy(3+)(2)] with densely packed distorted cuboid nanoscopic cages are reported for the first time. Magnetic characterization reveals that complex 1 shows a significant cryogenic magnetocaloric effect (-ΔSm = 44 J kg(-1) K(-1)), whereas 2 shows slow relaxation of magnetization. PMID:24689862

  17. "White" phosphor on the basis of Gd2(MoO4)3: Tm,Tb,Eu single crystal

    NASA Astrophysics Data System (ADS)

    Sinitsyn, V. V.; Redkin, B. S.; Kiselev, A. P.; Shmurak, S. Z.; Kolesnikov, N. N.; Kveder, V. V.; Ponyatovsky, E. G.

    2015-08-01

    A single-crystal sample of Gd2(MoO4)3 simultaneously doped with europium, terbium and thulium is grown. The Tm, Tb and Eu dopants are employed as the luminescent centers emitting light in the red, green and blue ranges. Spectroscopy investigation reveals that simultaneous luminescence of the centers of all three types to produce white light occurs only under the sample excitation with ultraviolet (UV) light within the wavelength range 350 < ? < 370 nm. A commercial UV light-emitting diode (LED) with ?LED = 365 nm is applied in order to show that the Gd2(MoO4)3:Tm,Tb,Eu crystal converts its UV flux into white light. So, it is demonstrated that white light may be produced using one matrix with luminous centers of three types.

  18. 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.

  19. 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

  20. Host-sensitized luminescence in LaNbO4:Ln(3+) (Ln(3+) = Eu(3+)/Tb(3+)/Dy(3+)) with different emission colors.

    PubMed

    Li, Kai; Zhang, Yang; Li, Xuejiao; Shang, Mengmeng; Lian, Hongzhou; Lin, Jun

    2015-02-14

    In this work, a series of Eu(3+), Tb(3+), and Dy(3+) singly-doped and co-doped LaNbO4 (LNO) phosphors have been synthesized by a high-temperature solid-state reaction route. X-ray diffraction (XRD) along with Rietveld refinement, diffuse reflection spectra, photoluminescence (PL) and cathodoluminescence (CL) properties, decay lifetimes, and PL quantum yields (QYs) were exploited to characterize the phosphors. Under UV excitation, energy transfer process from the host to the activators exists in the singly-doped samples, which leads to tunable emission color from blue to red for LNO:Eu(3+), green for LNO:Tb(3+), and yellow including white for LNO:Dy(3+). In Eu(3+) and Tb(3+) co-doped phosphors, LNO:Eu(3+), Tb(3+), the energy transfers from the host to the activators and Tb(3+) to Eu(3+) ions have also been deduced from the PL spectra, resulting in tunable emission color from green to red by adjusting the concentration ratio of Eu(3+) and Tb(3+) ions. The decay times monitored at host emission and Tb(3+) emission confirm the existence of energy transfer in the as-prepared samples. The best quantum efficiency can reach 43.2% for LNO:0.01Tb(3+) among all the as-prepared phosphors. In addition, the CL spectra of LNO:Eu(3+)/Tb(3+)/Dy(3+) are a little different from their PL spectra because another emission envelope around 530 nm appears in the samples, which is attributed to the bombardment of higher energy excitation source of low-voltage electron beam. However, the characteristic emissions similar to PL spectra were reserved. Moreover, the CL spectrum of LNO:0.02Tb(3+) has stronger emission intensity than that of ZnO:Zn commercial product. These results from the PL and CL properties of LNO:Eu(3+)/Tb(3+)/Dy(3+) suggest their potential in solid-state lighting and display fields. PMID:25573075

  1. Synthesis and anisotropic properties of single crystalline Ln2Ru3Al15+x (Ln=Gd, Tb)

    NASA Astrophysics Data System (ADS)

    Morrison, Gregory; Prestigiacomo, Joseph; Haldolaarachchige, Neel; Rai, Binod K.; Young, David P.; Stadler, Shane; Morosan, Emilia; Chan, Julia Y.

    2016-04-01

    Single crystals of Ln2Ru3Al15+x (Ln=Gd, Tb) have been grown using the self-flux method under Ru-poor conditions. The structure of the Gd analog is found to be highly dependent on the synthesis method. Gd2Ru3Al15.08 orders antiferromagnetically at 17.5 K. Tb2Ru3Al15.05 enters an antiferromagnetic state at 16.6 K followed by a likely incommensurate-to-commensurate transition at 14.9 K for crystals oriented with H//ab. For crystals oriented with H//c, a broad maximum is observed in the temperature dependent M/H, indicative of a highly anisotropic magnetic system with the hard axis in the c-direction. The magnetization as a function of field and magnetoresistance along the ab-direction of Tb2Ru3Al15.05 display a stepwise behavior and indicate strong crystalline electric field effects.

  2. Magnetic properties of DyCo{sub 5} and TbCo{sub 5} intermetallics from the electronic structure calculations

    SciTech Connect

    Miletic, G.I. Blazina, Z.

    2007-02-15

    LSDA and LSDA+U calculations, with spin-orbit coupling (SOC) included, were performed for DyCo{sub 5} and TbCo{sub 5} intermetallic compounds. In the case of magnetic moments, LSDA-SOC calculations give results in good agreement with the experimental data. However, LSDA has shown to be unable to predict relative stabilities of ferromagnetic and ferrimagnetic configurations of the 4f and 3d spin sublattices giving the wrong result that the ferromagnetic configuration is more stable. LSDA+U method cures this problem and gives correct result. Additionally, within the accuracy of available experimental data, the corresponding effective exchange fields are in reasonable agreement with experiment.

  3. Aligned sintered compacts of RBa2Cu3O(7-x) (R = Dy, Er, Eu, Gd, Ho, Y)

    NASA Astrophysics Data System (ADS)

    Arendt, R. H.; Gaddipati, A. R.; Garbauskas, M. F.; Hall, E. L.; Hart, H. R.

    X-ray, microscopic, and magnetic measurements have been obtained in order to investigate sintered compacts of magnetically aligned single-crystal particles. It is found that magnetic fields and pressure can yield substantial alignment of RBa2Cu3O(7-x) grains, even at sintering densities. The c-axis is shown to preferentially align parallel to the field for R = Dy, Ho, and Y, but to be normal to the field for R = Er, Eu, and Gd. Although strongly anisotropic hysteresis curves are obtained, the bulk critical current density remains low. It is suggested that the final alignment may be determined by the morphology and final packing of the grains, and not by the magnetic torque alone.

  4. Les oxydes A2BaCuO 5 ( A = Y, Sm, Eu, Gd, Dy, Ho, Er, Yb)

    NASA Astrophysics Data System (ADS)

    Michel, C.; Raveau, B.

    1982-06-01

    A series of new phases, A2BaCuO 5 ( A = Y, Sm, Eu, Gd, Dy, Ho, Er, Yb), has been isolated. These compounds are orthorhombic, with a ⋍ 7.1, b ⋍ 12.2, and c ⋍ 5.6Å. The probable space groups deduced from the electron diffraction patterns are Pbnm and Pbn2 1. The structure has been resolved from X-ray powder patterns. The framework can be considered as built up from distorted monocapped trigonal prisms AO 7 which share one triangular face forming A2O 11 blocks. The edge-sharing A2O 11 blocks form a three-dimensional network which delimits cavities where Ba 2+ and Cu 2+ are located. Barium is coordinated to 11 oxygen atoms, while the coordination polyhedron of copper is a distorted tetragonal pyramid CuO 5.

  5. Structural Transition and Enhanced Ferromagnetic Properties of La, Nd, Gd, and Dy-Doped BiFeO3 Ceramics

    NASA Astrophysics Data System (ADS)

    Kumar, Ashwini; Varshney, Dinesh

    2015-11-01

    The structural, electrical, and magnetic properties of rare-earth-doped Bi0.8 RE0.2FeO3 ceramics (rare-earth (RE) = La, Nd, Gd, and Dy) synthesized by solid-state reaction are reported and discussed. The x-ray diffraction (XRD) patterns of Bi0.8La0.2FeO3 and Bi0.8Nd0.2FeO3 were indexed to rhombohedral ( R3 c) and triclinic ( P1) structures, respectively. Rietveld refinement of the XRD pattern of Bi0.8Dy0.2FeO3 confirmed its biphasic nature ( Pnma + R3 c space groups) whereas for Bi0.8Gd0.2FeO3 the orthorhombic phase with Pna21 symmetry made a major contribution, with minor contributions from the orthorhombic ( Pnma) and rhombohedral ( R3 c) phases. Raman spectroscopy revealed changes in BiFeO3 mode positions, in addition to structural changes, on RE ion substitution. The effect of RE ion substitution on dielectric constant and loss tangent were studied at room temperature in a wide range of frequency, 50 Hz-1 MHz. Room temperature magnetization-magnetic field ( M- H) measurements indicated that magnetization increased with increasing structural distortion and with partial destruction of the spin cycloid as a result of doping of BiFeO3 ceramics with rare earth ions. These compounds, with improved remnant magnetization and coercive field, are suitable for use in spin-based electronic devices.

  6. 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.

  7. 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

  8. An ultrasmall and metabolizable PEGylated NaGdF4:Dy nanoprobe for high-performance T1/T2-weighted MR and CT multimodal imaging

    NASA Astrophysics Data System (ADS)

    Jin, Xiaoying; Fang, Fang; Liu, Jianhua; Jiang, Chunhuan; Han, Xueli; Song, Zhongkai; Chen, Jinxing; Sun, Guoying; Lei, Hao; Lu, Lehui

    2015-09-01

    Lanthanide-based multimodal probes with high sensitivity, simple synthesis strategy, and good biocompatibility promise new applications for clinical diagnosis. However, today's challenge is not only to develop high-performance multimodal probes for more accurate and reliable diagnosis, but also to understand the fate of these probes in vivo. In this context, a novel PEGylated Dy-doped NaGdF4 nanoprobe (PEG-NaGdF4:Dy) was designed and fabricated as a T1/T2-weighted MRI/CT imaging agent. This nanoprobe has a distinct longitudinal relaxivity (r1 = 5.17 mM-1 s-1), relatively high transverse relaxivity (r2 = 10.64 mM-1 s-1), and exhibits strong X-ray attenuation properties (44.70 HU L g-1) in vitro. Furthermore, T1/T2-weighted MRI/CT imaging in vivo confirmed that this PEG-NaGdF4:Dy nanoprobe could lead to a significant contrast enhancement effect on liver, spleen and kidney at 24 h post injection. The MTT assay, histological analysis, and biodistribution investigation demonstrated that this multifunctional nanoprobe possessed relatively low cytotoxicity, negligible tissue damage and could be completely excreted out of the body of mice as time prolonged. Therefore, the present PEG-NaGdF4:Dy nanoprobe has the potential for the development of multifunctional T1/T2-weighted MRI/CT imaging to provide more comprehensive and accurate diagnosis information.Lanthanide-based multimodal probes with high sensitivity, simple synthesis strategy, and good biocompatibility promise new applications for clinical diagnosis. However, today's challenge is not only to develop high-performance multimodal probes for more accurate and reliable diagnosis, but also to understand the fate of these probes in vivo. In this context, a novel PEGylated Dy-doped NaGdF4 nanoprobe (PEG-NaGdF4:Dy) was designed and fabricated as a T1/T2-weighted MRI/CT imaging agent. This nanoprobe has a distinct longitudinal relaxivity (r1 = 5.17 mM-1 s-1), relatively high transverse relaxivity (r2 = 10.64 mM-1 s-1), and exhibits strong X-ray attenuation properties (44.70 HU L g-1) in vitro. Furthermore, T1/T2-weighted MRI/CT imaging in vivo confirmed that this PEG-NaGdF4:Dy nanoprobe could lead to a significant contrast enhancement effect on liver, spleen and kidney at 24 h post injection. The MTT assay, histological analysis, and biodistribution investigation demonstrated that this multifunctional nanoprobe possessed relatively low cytotoxicity, negligible tissue damage and could be completely excreted out of the body of mice as time prolonged. Therefore, the present PEG-NaGdF4:Dy nanoprobe has the potential for the development of multifunctional T1/T2-weighted MRI/CT imaging to provide more comprehensive and accurate diagnosis information. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04065e

  9. Magnetic Ground States of the Rare-Earth Tripod Kagome Lattice Mg2 RE3 Sb3 O14 (RE =Gd ,Dy ,Er )

    NASA Astrophysics Data System (ADS)

    Dun, Z. L.; Trinh, J.; Li, K.; Lee, M.; Chen, K. W.; Baumbach, R.; Hu, Y. F.; Wang, Y. X.; Choi, E. S.; Shastry, B. S.; Ramirez, A. P.; Zhou, H. D.

    2016-04-01

    We present the structural and magnetic properties of a new compound family, Mg2 RE3 Sb3 O14 (RE =Gd ,Dy ,Er ), with a hitherto unstudied frustrating lattice, the "tripod kagome" structure. Susceptibility (ac, dc) and specific heat exhibit features that are understood within a simple Luttinger-Tisza-type theory. For RE =Gd , we found long-ranged order (LRO) at 1.65 K, which is consistent with a 120° structure, demonstrating the importance of diople interactions for this 2D Heisenberg system. For RE =Dy , LRO at 0.37 K is related to the "kagome spin ice" physics for a 2D system. This result shows that the tripod kagome structure accelerates the transition to LRO predicted for the related pyrochlore systems. For RE =Er , two transitions, at 80 mK and 2.1 K are observed, suggesting the importance of quantum fluctuations for this putative X Y system.

  10. Real and imaginary components of the alternating current magnetic susceptibility of RAl2 (R=Gd, Dy, and Er) in the ferromagnetic region

    NASA Astrophysics Data System (ADS)

    Levin, E. M.; Pecharsky, V. K.; Gschneidner, K. A.

    2001-12-01

    The real (χac') and imaginary (χac″) components of the ac magnetic susceptibility of the polycrystalline GdAl2, DyAl2, and ErAl2 have been measured as functions of temperature, ac and bias dc magnetic field amplitude, and ac magnetic field frequency. Both χac' and χac″ of the ferromagnetic DyAl2 and ErAl2 are strongly dependent on the ac magnetic field parameters, especially when compared with those of the ferromagnetic GdAl2. The observed behavior of the ac magnetic susceptibility is determined mainly by the domain dynamics, rather than by a change of the exchange interactions below Curie temperature.

  11. The lanthanoid(III) chloride cyclo-tetrasilicates M{sub 6}Cl{sub 10}[Si{sub 4}O{sub 12}] (M=Sm, Gd-Dy): Synthesis, structure and IR investigations

    SciTech Connect

    Hartenbach, Ingo . E-mail: hartenbach@iac.uni-stuttgart.de; Jagiella, Stefan; Schleid, Thomas . E-mail: schleid@iac.uni-stuttgart.de

    2006-08-15

    The chloride derivatized lanthanoid(III) cyclo-tetrasilicates of the composition M{sub 6}Cl{sub 10}[Si{sub 4}O{sub 12}] (M=Sm, Gd-Dy) crystallize monoclinically in space group C2/m (a=1062-1065, b=1036-1052, c=1163-1187pm, {beta}{approx}103{sup o}, Z=2). They are obtained by the reaction of the sesquioxides M{sub 2}O{sub 3} (or the combination of Tb{sub 4}O{sub 7} and Tb in 3:2-molar ratio for the terbium case), the corresponding trichlorides MCl{sub 3}, and SiO{sub 2} (silica gel) in stoichiometric ratios with double the amount of MCl{sub 3} as flux in evacuated silica tubes (7d at 850deg. C) as transparent, pseudo-octagonal, pillar-shaped single crystals with the colour of the respective lanthanoid trication M{sup 3+}. Their crystal structure can be considered as a layered arrangement in which cationic {sub {approx}}{sup 2}{l_brace}[(M2){sub 5}Cl{sub 9}]{sup 6+}{r_brace} layers are alternatingly piled with anionic ones of the kind {sub {approx}}{sup 2}{l_brace}[(M1)Cl[Si{sub 4}O{sub 12}

  12. Controlling the Two-Photon-Induced Photon Cascade Emission in a Gd(3+)/Tb(3+)-Codoped Glass for Multicolor Display.

    PubMed

    Yuan, Mao-Hui; Fan, Hai-Hua; Li, Hui; Lan, Sheng; Tie, Shao-Long; Yang, Zhong-Min

    2016-01-01

    We reported the first observation of the two-photon-induced quantum cutting phenomenon in a Gd(3+)/Tb(3+)-codoped glass in which two photons at ~400 nm are simultaneously absorbed, leading to the cascade emission of three photons in the visible spectral region. The two-photon absorption induced by femtosecond laser pulses allows the excitation of the energy states in Gd(3+) which are inactive for single-photon excitation and enables the observation of many new electric transitions which are invisible in the single-photon-induced luminescence. The competition between the two-photon-induced photon cascade emission and the single-photon-induced emission was manipulated to control the luminescence color of the glass. We demonstrated the change of the luminescence color from red to yellow and eventually to green by varying either the excitation wavelength or the excitation power density. PMID:26899189

  13. Controlling the Two-Photon-Induced Photon Cascade Emission in a Gd3+/Tb3+-Codoped Glass for Multicolor Display

    PubMed Central

    Yuan, Mao-Hui; Fan, Hai-Hua; Li, Hui; Lan, Sheng; Tie, Shao-Long; Yang, Zhong-Min

    2016-01-01

    We reported the first observation of the two-photon-induced quantum cutting phenomenon in a Gd3+/Tb3+-codoped glass in which two photons at ~400 nm are simultaneously absorbed, leading to the cascade emission of three photons in the visible spectral region. The two-photon absorption induced by femtosecond laser pulses allows the excitation of the energy states in Gd3+ which are inactive for single-photon excitation and enables the observation of many new electric transitions which are invisible in the single-photon-induced luminescence. The competition between the two-photon-induced photon cascade emission and the single-photon-induced emission was manipulated to control the luminescence color of the glass. We demonstrated the change of the luminescence color from red to yellow and eventually to green by varying either the excitation wavelength or the excitation power density. PMID:26899189

  14. Controlling the Two-Photon-Induced Photon Cascade Emission in a Gd3+/Tb3+-Codoped Glass for Multicolor Display

    NASA Astrophysics Data System (ADS)

    Yuan, Mao-Hui; Fan, Hai-Hua; Li, Hui; Lan, Sheng; Tie, Shao-Long; Yang, Zhong-Min

    2016-02-01

    We reported the first observation of the two-photon-induced quantum cutting phenomenon in a Gd3+/Tb3+-codoped glass in which two photons at ~400 nm are simultaneously absorbed, leading to the cascade emission of three photons in the visible spectral region. The two-photon absorption induced by femtosecond laser pulses allows the excitation of the energy states in Gd3+ which are inactive for single-photon excitation and enables the observation of many new electric transitions which are invisible in the single-photon-induced luminescence. The competition between the two-photon-induced photon cascade emission and the single-photon-induced emission was manipulated to control the luminescence color of the glass. We demonstrated the change of the luminescence color from red to yellow and eventually to green by varying either the excitation wavelength or the excitation power density.

  15. A structural, magnetostrictive and Mössbauer study of Tb0.3Dy0.7(Fe0.9 T 0.1)1.95 alloys

    NASA Astrophysics Data System (ADS)

    Zheng, Xiaoping; Zhang, Peifeng; Fan, Duowang; Li, Fashen; Hao, Yuan

    2005-11-01

    The effect of IIIA metal and transition metal T substitution for Fe on crystal structure, magnetostriction and spontaneous magnetostriction, anisotropy and spin reorientation of a series of polycrystalline Tb0.3 Dy0.7 (Fe0.9 T 0.1)1.95 ( T=Mn, Fe, Co, B, Al, Ga) alloys at room temperature were investigated systematically. It was found that the primary phase of the Tb0.3 Dy0.7 (Fe0.9 T 0.1)1.95 alloys is the MgCu2-type cubic Laves phase structure for different substitution. The magnetostriction λ s decrases greatly for the substitution of IIIA metal, B, Al and Ga, but is saturated more easily for Al and Ga substitution, showing that the Al and Ga substitution is beneficial to a decrease in the magnetocrystalline anisotropy of Tb0.3 Dy0.7 (Fe0.9 T 0.1)1.95 alloys. However, the substitution of transition metal Mn and Co decreases slightly the magnetostriction λ s . It was also found that the effect of different substitutions on the spontaneous magnetostriction λ 111 is distinct. The analysis of the Mössbauer spectra indicates that the easy magnetization direction in the {110} plane deviates slightly from the main axis of symmetry for Al and Ga substitution, namely spin reorientation, but it does not change evidently for B, Mn and Co substitution.

  16. Effect of cooling rate on magnetostriction gradients of Tb0.27Dy0.73Fe1.95 alloys solidified in high magnetic field gradients

    NASA Astrophysics Data System (ADS)

    Liu, Tie; Gao, Peng-Fei; Dong, Meng; Xiao, Yu-Bao; Wang, Qiang

    2016-05-01

    In this work, Tb0.27Dy0.73Fe1.95 alloys were solidified in a high magnetic field gradient (8.8 T, -565 T2/m) at various cooling rates. Changes in the magnetostriction, crystal orientation, and magnetization of the alloys were investigated. The application of the magnetic field gradient has a strong influence on the magnetostrictive performance. At lower cooling rates, the maximum magnetostriction increases gradually with depth from the top surface of the alloys. However, the effect of the magnetic field gradient is strongly dependent on the cooling rate. With increasing cooling rate, the magnetostriction gradient decreases. The magnetization measurement shows that the saturation magnetization at lower cooling rates increases gradually with depth from the top surface of the alloys. However, with increasing cooling rate, the increase in the saturation magnetization is reduced. The XRD measurement results show that the orientation behavior of the (Tb, Dy)Fe2 phase exhibits a continuous change throughout the alloys at lower cooling rates, but is almost unchanged at higher cooling rates. The change in the magnetostriction of the alloys can be attributed to the changes in crystal orientation and the amount of the (Tb, Dy)Fe2 phase in the alloys caused by both the magnetic field gradient and cooling rate.

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

    SciTech Connect

    Loginov, Yu. E. Zinoviev, V. G.; Kabina, L. P.; Lisin, S. S.; Maljutenkov, Ed. I.

    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.

  18. Wheel-shaped nanoscale 3d-4f {Co(II)16Ln(III)24} clusters (Ln = Dy and Gd).

    PubMed

    Zhang, Ze-Min; Pan, Lu-Yi; Lin, Wei-Quan; Leng, Ji-Dong; Guo, Fu-Sheng; Chen, Yan-Cong; Liu, Jun-Liang; Tong, Ming-Liang

    2013-09-21

    Two unprecedented wheel-shaped nanoscale clusters {Co(II)16Ln(III)24} (Ln = Dy and Gd), with a diameter and a thickness of 3.0 nm and 2.0 nm, respectively, were obtained from the self-assembly of Co(NO3)2, Ln(NO3)3 and a pyridyl-functionalized β-diketone ligand. Notably, the gadolinium species exhibited a relatively large magnetocaloric effect. PMID:23912749

  19. The hydration properties of Gd(III) and Tb(III): An ab initio quantum mechanical molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Canaval, Lorenz R.; Passler, Peter P.; Rode, Bernd M.

    2015-04-01

    The quantum mechanical charge-field molecular dynamics (QMCF-MD) simulation method was employed to study the hydration properties of gadolinium(III) and terbium(III). Slight differences of the solvation shells' structural and dynamical properties were discovered. While the Lnsbnd O radial distribution functions are in excellent agreement with recent experiments, average coordination numbers of 8.5 (Gd) and 8.4 (Tb) were found. Vivid ligand exchange dynamics along with rapid intrashell rearrangements were observed, underlined by mean residence times in the picosecond range, which is characteristic for trivalent lanthanoides according to quantum mechanical simulations. Vibrational analysis yielded ion-water force constants below 100 N m-1.

  20. Structural refinement, band-gap analysis and optical properties of GdAlO3 nanophosphors influenced by Dy3+ ion concentrations for white light emitting device applications

    NASA Astrophysics Data System (ADS)

    Jisha, P. K.; Naik, Ramachandra; Prashantha, S. C.; Nagaswarupa, H. P.; Nagabhushana, H.; Basavaraj, R. B.; Sharma, S. C.; Prasad, Daruka

    2016-04-01

    Nanosized GdAlO3 phosphors activated with Dy3+ were prepared by a combustion method. Synthesized phosphors were calcined at 1000 °C for 3 h in order to achieve crystallinity. Powder x-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis was used to characterize the prepared product. The orthorhombic phase was observed in the XRD pattern. The particle size of the samples was calculated as around 25 nm. The SEM images show an irregular shape of the prepared nanophosphor. Functional groups of the phosphors were examined by Fourier transform infrared (FTIR) spectroscopy. Photoluminescence (PL) properties of Dy3+ doped GdAlO3 for near-ultraviolet excitation (352 nm) were studied in order to investigate the possibility of its use in white light emitting device applications. Judd–Ofelt intensity parameters, radiative transition rate (A T) and radiative lifetimes (τ rad) were evaluated from the emission spectrum by adopting a standard procedure. The Commission International de l’Eclairage (CIE) color coordinates and correlated color temperature (CCT) are studied for the optimized phosphor. It is found that the color coordinates of Dy3+ doped GdAlO3 powders fall in the white region of the CIE diagram, and the average CCT value was found to be about 6276 K. Therefore, the present phosphor is highly useful for display applications.

  1. Photoluminescence and thermoluminescence properties of Tb{sup 3+} doped K{sub 3}Gd(PO{sub 4}){sub 2} nanophosphor

    SciTech Connect

    Gupta, Palvi; Bedyal, A.K.; Kumar, Vinay; Khajuria, Y.; Lochab, S.P.; Pitale, S.S.; Ntwaeaborwa, O.M.; Swart, H.C.

    2014-12-15

    Energy level diagram of Tb{sup 3+} ion in the K{sub 3}Gd(PO{sub 4}){sub 2} host lattice. - Highlights: • First time, a detailed TL and PL study on undoped and Tb{sup 3+} doped K{sub 3}Gd(PO{sub 4}){sub 2} nanophosphor. • Combustion method was employed to synthesize the Tb{sup 3+} doped K{sub 3}Gd(PO{sub 4}){sub 2} nanophosphor. • Mechanism of excitation and emission in undoped and Tb{sup 3+} doped K{sub 3}Gd(PO{sub 4}){sub 2} nanophosphor was given. - Abstract: Tb{sup 3+} doped nanoparticulate K{sub 3}Gd(PO{sub 4}){sub 2} phosphor was prepared by combustion method using urea as a fuel. The structure, optical and luminescent properties of the phosphor were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and thermoluminescence (TL) spectroscopy. In undoped K{sub 3}Gd(PO{sub 4}){sub 2}, the excitation and emission peaks at 273 nm and 323 nm belongs to the {sup 8}S{sub 7/2} → {sup 6}I{sub J(J=7/2)} and {sup 6}P{sub J(J=7/2)} → {sup 8} S{sub 7/2} transitions of Gd{sup 3+} while green emission was observed in the Tb{sup 3+} doped K{sub 3}Gd(PO{sub 4}){sub 2}. TL study was carried out after exposing the samples to γ-radiations (0.1–5 kGy) in the K{sub 3}Gd(PO{sub 4}){sub 2}:Tb{sup 3+} (1.5 mol%). The calculated kinetic parameters were compared with different methods. The band gap of the phosphor was estimated as 5.80 eV. The green shade of the Tb{sup 3+} ion with the CIE coordinates (x, y) as (0.29, 0.54) was in good agreement with the well known green phosphors.

  2. One-dimensional GdVO{sub 4}:Ln{sup 3+} (Ln=Eu, Dy, Sm) nanofibers: Electrospinning preparation and luminescence properties

    SciTech Connect

    Li, Xue; Yu, Min; Hou, Zhiyao; Li, Guogang; Ma, Ping'an; Wang, Wenxin; Cheng, Ziyong; Lin, Jun

    2011-01-15

    One-dimensional GdVO{sub 4}:Ln{sup 3+} (Ln=Eu, Dy, Sm) nanofibers have been prepared by a combination method of sol-gel process and electrospinning technology. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL), quantum efficiency (QE), and cathodoluminescence (CL) spectra as well as kinetic decays were used to characterize the samples. The XRD, FT-IR, and TG-DTA results show that GdVO{sub 4}:Ln{sup 3+} nanofibers samples crystallize at 700 {sup o}C. SEM images indicate that the as prepared precursor fibers are smooth. After being calcined at 700 {sup o}C for 4 h, the fibers still maintain their fiberlike morphology with rough surface. TEM image further manifests that the GdVO{sub 4}:Ln{sup 3+} nanofibers consist of nanoparticles. Under ultraviolet excitation and low-voltage electron beam excitation, GdVO{sub 4}:Ln{sup 3+} phosphors showed their strong characteristic emission due to an efficient energy transfer from vanadate groups to dopants. The optimum doping concentration of Ln{sup 3+} in the GdVO{sub 4} nanofibers also has been investigated. -- Graphical abstract: Display Omitted Research Highlights: {yields}1D and Q-1D GdVO{sub 4} fiber-like nanostructures were prepared electrospinning technique. {yields}Under ultraviolet excitation and electron beam excitation, the Ln{sup 3+} ions show their characteristic emissions, respectively. {yields}The quantum efficiencies are 14 (Eu{sup 3+}), 6 (Dy{sup 3+}), and 5 % (Sm{sup 3+}) in GdVO{sub 4}, respectively.

  3. Topography, domain structure, and magnetostriction measurements on Tb0.5Dy0.5Fe2 under stress (abstract)

    NASA Astrophysics Data System (ADS)

    Savage, H. T.; Clark, A. E.; Lord, D. L.; McMasters, O. D.

    1985-04-01

    We have characterized a textured cylindrical sample of Tb0.5Dy0.5Fe2 (54 mm×6 mm diam) by topography and metallography. The topography shows long ( 20 mm) slender grains with a [110] axis along the sample axis. The grain boundaries are less than 1°. Domain walls can be seen by both Berg-Barrett technique and optical observations. This composition has a large anisotropy, Ki=5×106 erg/cm3. We find that under stress the magnetization occurs by ``jumping'' of the moment from a [111] axis perpendicular to the axis to the [111] direction closest to the axis of the sample. A large hysteresis accompanies this effect. In comparison with samples of other RFe2 (R=rare earth) compositions, the results of the high stress magnetization and magnetostriction experiments show two features: (1) the sample saturates with a much sharper ``knee,'' and (2) a much higher energy conversion is obtained. We conjecture the difference between this sample and the other RFe2 compounds is its lack of Widmanstatten precipitate, i.e., a much higher sample perfection.

  4. Narrow spectral emission CaMoO{sub 4}: Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+} phosphor crystals for white light emitting diodes

    SciTech Connect

    Khanna, A.; Electrical, Computer and Systems Engineering Department, Rensselaer Polytechnic Institute, 110, 8th Street, Troy, New York, 12180 ; Dutta, P.S.

    2013-02-15

    Alkaline earth metal molybdates are promising candidates as a host material for high efficiency narrow spectral emission phosphors. These phosphors could potentially be used for the fabrication of phosphor-converted light emitting diodes (pc-LEDs). Phosphor crystals of calcium molybdate doped with rare earth dopant Ln{sup 3+}(Ln=Eu, Dy, Tb) grown using flux growth method have been shown to exhibit higher excitation efficiency than the powders synthesized by solid-state reaction process. Molybdenum (VI) oxide has been found to be a suitable flux for growing large size optically transparent high quality crystals at a temperature around 1100 Degree-Sign C. Using the excitation wavelengths of 465 nm, 454 nm and 489 nm for CaMoO{sub 4}: Eu{sup 3+}, CaMoO{sub 4}: Dy{sup 3+} and CaMoO{sub 4}: Tb{sup 3+}, respectively, intense emission lines at wavelengths of 615 nm, 575 nm and 550 nm were observed. The optimized doping concentrations of 12%, 2% and 5% for Eu{sup 3+}, Dy{sup 3+} and Tb{sup 3+}, respectively, provided the highest luminescence intensity. - Graphical Abstract: CaMoO{sub 4}: Eu{sup 3+} phosphor crystals grown using a molybdenum (VI) oxide flux exhibited around 1.5 times the emission intensity of powders obtained from solid-state reaction at the same synthesis temperature. These crystals were found to efficiently emit 615 nm red light when excited by near UV light up to a wavelength of 395 nm. Highlights: Black-Right-Pointing-Pointer CaMoO{sub 4}: Ln{sup 3+} (Ln=Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+}) phosphor crystals were successfully grown using high temperature flux (solutions) containing molybdenum (VI) oxide or lithium chloride. Black-Right-Pointing-Pointer Narrow spectral emission at 615 nm, 575 nm and 550 nm, respectively, was observed from CaMoO{sub 4}: Ln{sup 3+} (Ln=Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+}) phosphor crystals. Black-Right-Pointing-Pointer The optimized doping concentrations of Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+} in CaMoO{sub 4} for highest emission intensity were determined to be 12%, 2% and 5%, respectively. Black-Right-Pointing-Pointer The CaMoO{sub 4}: Ln{sup 3+} (Ln=Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+}) phosphor crystals grown with molybdenum (VI) oxide flux exhibited 50% higher emission intensity compared to the crystals grown with lithium chloride flux and the powders synthesized by solid-state reaction.

  5. Magnetic properties of CaCu5-type RNi3TSi (R=Gd and Tb, T=Mn, Fe, Co and Cu) compounds

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    Magnetic properties and magnetocaloric effect of CaCu5-type RNi3TSi (R=Gd and Tb, T=Mn, Fe, Co and Cu) compounds have been investigated. Magnetic measurements of RNi3TSi display the increasing of Curie temperature and the decreasing of magnetocaloric effect and saturated magnetic moment in the row of 'RNi3CuSi-RNi3NiSi-RNi3CoSi-RNi3MnSi-RNi3FeSi'. In contrast to GdNi3{Mn, Fe, Co}Si, TbNi3{Mn, Fe, Co}Si exhibit significant magnetic hysteresis. The coercive field increases from TbNi4Si ( 0.5 kOe) to TbNi3CoSi (4 kOe), TbNi3MnSi (13 kOe) and TbNi3FeSi (16 kOe) in field of 50 kOe at 5 K, whereas TbNi3CuSi exhibits a negligible coercive field.

  6. Synthesis, structural, and magnetic characterization of new Hg{sub 2}Ba{sub 2}LnCu{sub 2}O{sub 8-{delta}} phases with Ln = Nd-Gd, Dy-Lu

    SciTech Connect

    Loureiro, S.M.; Chaillout, C. Gautier, E.

    1997-08-01

    New phases of general formula Hg{sub 2}Ba{sub 2}LnCu{sub 2}O{sub 8-{delta}} with Ln = Nd-Gd, Dy-Lu were synthesized by high-pressure, high-temperature technique. All the compounds crystallize in space group I 4/m m m and the lattice parameters were found to increase with the ionic radii, ranging from a = 3.8460(3) {angstrom}, c = 28.853(3) {angstrom} for Lu up to a = 3.9021(3) {angstrom}, c = 28.986(3) {angstrom} for Nd. Hg-2212 phases were not obtained with La, due to the high ionic radius of La{sup 3+}, or with cations having possible valences higher than (+3), such as Tb, Pr, and Ce. Energy dispersive spectroscopy (EDS) analysis performed on samples with Lu, Yb, Er, and Gd showed significant Hg-deficiency as well as rare earth overstoichiometry. This allows us to suggest that lanthanide cations partially substitute for Hg and that these phases are better described as (Hg, Ln){sub 2}BA{sub 2}LnCu{sub 2}O{sub 8-{delta}}. The substitution rate depends on the ionic radii of the lanthanide cation, varying between 25% for Lu (0.977 {angstrom}) or ER (1.004 {angstrom}) to 15% for Gd (1.053 {angstrom}). In the case of Nd-sample it was found that Nd does not replace Hg but Ba instead. The large ionic radius of Nd (1.109 {angstrom}) can probably account for this effect and this phase would be described as Hg{sub 2}(Ba, Nd){sub 2}NdCu{sub 2}O{sub 8-{delta}}. The susceptibility of Sm, Eu, Dy, and Ho samples exhibits a sharp cusp at a temperature T{sub L} between 25 and 28 K. These temperatures are attributed to the antiferromagnetic binding of Cu spins, because they are too high to be due to rare earth ordering. Specific heat and neutron diffraction experiments are planned to establish an eventual cooperative ordering of Cu and rare earth moments.

  7. Hydrothermal synthesis, characterization and luminescent properties of GdPO{sub 4}·H{sub 2}O:Tb{sup 3+} nanorods and nanobundles

    SciTech Connect

    Song, Hejuan Zhou, Liqun Li, Ling; Hong, Fei; Luo, Xinru

    2013-12-15

    Graphical abstract: - Highlights: • The GdPO{sub 4}·H{sub 2}O:Tb{sup 3+} nanocrystals have been synthesized via a hydrothermal method. • The formation mechanisms of the nanorods and nanobundles were put forward. • The luminescent intensities are associated with the morphologies and sizes. - Abstract: In this paper, the Tb{sup 3+}-doped GdPO{sub 4}·H{sub 2}O nanorods and nanobundles have been synthesized by the hydrothermal method with and without glycine, respectively. The X-ray powder diffraction (XRD), thermogravimetric and differential thermal analysis (TG–DTA), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), energy-dispersive spectra (EDS) and photoluminescence (PL) were employed to characterize the as-obtained products. It was found that the addition of glycine and the pH value have crucial influences on the formation of the resulting morphologies and sizes. The possible formation mechanisms for GdPO{sub 4}·H{sub 2}O:Tb{sup 3+} nanorods and nanobundles were put forward. A detailed investigation on the photoluminescence of GdPO{sub 4}·H{sub 2}O:Tb{sup 3+} different samples revealed that the luminescent properties of products are strongly correlated with the morphologies, sizes, coordination environment and crystal field symmetry.

  8. Influence of structural distortions upon photoluminescence properties of Eu{sup 3+} and Tb{sup 3+} activated Na{sub 3}Ln(BO{sub 3}){sub 2} (Ln=Y, Gd) borates

    SciTech Connect

    Asiri Naidu, S.; Boudin, S.; Varadaraju, U.V.; Raveau, B.

    2012-06-15

    The comparative study of the structure and photoluminescence (PL) properties of the Eu{sup 3+} and Tb{sup 3+} activated Na{sub 3}Ln(BO{sub 3}){sub 2}, with Ln=Y, Gd, showed the important role of the host lattice structure upon PL. Higher emission intensities of Eu{sup 3+} and Tb{sup 3+} are observed for Na{sub 3}Gd(BO{sub 3}){sub 2} than for Na{sub 3}Y(BO{sub 3}){sub 2}, through direct Eu{sup 3+} excitation at 395 nm for Eu{sup 3+} doped borates, and through Gd{sup 3+} excitation around 280 nm for Tb{sup 3+} doped borates. This higher performance for Na{sub 3}Gd(BO{sub 3}){sub 2} is due to the less regular environment of Eu{sup 3+} (Tb{sup 3+}) in the Gd sites than in the Y sites and to energy transfer from Gd{sup 3+} to Eu{sup 3+}(Tb{sup 3+}). The smaller critical concentration in Na{sub 3}Ln{sub 1-x}Tb{sub x}(BO{sub 3}){sub 2} observed for Ln=Gd, x=0.5, compared to x=0.6 for Ln=Y, is explained by shorter Ln-Ln distances (4.11 A for Gd-Gd vs. 4.59 A for Y-Y). Both Na{sub 3}Y{sub 0.4}Tb{sub 0.6}(BO{sub 3}){sub 2} and Na{sub 3}Gd{sub 0.5}Tb{sub 0.5}(BO{sub 3}){sub 2} show intense green emission under UV excitation. - Graphical abstract: The PL properties of Eu{sup 3+} and Tb{sup 3+} are studied in Na{sub 3}Ln(BO{sub 3}){sub 2} (Ln=Y, Gd) borates. Eu{sup 3+} and Tb{sup 3+}exhibits higher emission intensity in Na{sub 3}Gd(BO{sub 3}){sub 2} compared to Na{sub 3}Y(BO{sub 3}){sub 2} due to the less regular environment of the Gd{sup 3+} ion. Energy transfer from Gd{sup 3+} to Tb{sup 3+} is observed. Highlights: Black-Right-Pointing-Pointer Crystal structure of Na{sub 3}Gd(BO{sub 3}){sub 2} by X-ray powder diffraction. Black-Right-Pointing-Pointer Photoluminescence properties of Eu{sup 3+} and Tb{sup 3+} doped Na{sub 3}Ln(BO{sub 3}){sub 2} (Ln=Y, Gd). Black-Right-Pointing-Pointer Higher Eu{sup 3+} and Tb{sup 3+} emission for Na{sub 3}Gd(BO{sub 3}){sub 2} due to an irregular environment of Gd{sup 3+}. Black-Right-Pointing-Pointer Higher Eu{sup 3+} and Tb{sup 3+} emission for Na{sub 3}Gd(BO{sub 3}){sub 2} due to energy transfer from Gd{sup 3+}. Black-Right-Pointing-Pointer Lower Tb{sup 3+} critical concentration for Na{sub 3}Gd(BO{sub 3}){sub 2} due to short Gd{sup 3+}-Gd{sup 3+} distances.

  9. 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; Murillo, A. Garcia; Romo, F. de J. Carrillo; Hernandez, M. Garcia; Vigueras, D. Jaramillo

    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.

  10. Increase in the Tb{sup 3+} green emission in SiO{sub 2}-LaF{sub 3} nano-glass-ceramics by codoping with Dy{sup 3+} ions

    SciTech Connect

    Velazquez, J. J.; Rodriguez, V. D.; Mendez-Ramos, J.; Yanes, A. C.; Castillo, J. del

    2010-12-01

    95SiO{sub 2}-5LaF{sub 3} sol-gel derived nano-glass-ceramics single doped with 0.1Dy{sup 3+} or 0.1Tb{sup 3+} mol % and codoped with 0.1Dy{sup 3+} and xTb{sup 3+} (x=0.1,0.3) mol % were successfully obtained. XRD and HRTEM measurements confirm the precipitation of LaF{sub 3} nanocrystals during the ceramming process, with mean size ranging from 10 to 20 nm and increasing with the thermal treatment temperature. About 75% of lanthanide ions are partitioned into LaF{sub 3} nanocrystals, as calculated from luminescence decays. The effect of increasing the Tb{sup 3+} concentration and also of codoping with Dy{sup 3+} in the Tb{sup 3+} green emission from the {sup 5}D{sub 4} level have been studied. The energy transfer mechanisms between Tb{sup 3+} ions and also between Tb{sup 3+}-Dy{sup 3+} ions, which favor the green emission, have been analyzed.

  11. Crystal structure, electronic and physical properties of monoclinic RECuTe2 in contrast to RECuSe2 (RE = Pr, Sm, Gd, Dy and Er)

    NASA Astrophysics Data System (ADS)

    Esmaeili, Mehdi; Forbes, Scott; Tseng, Yu-Chih; Mozharivskyj, Yurij

    2014-10-01

    The ternary tellurides RECuTe2 (RE = Gd, Dy and Er) have been synthesized, their crystal structure and charge transport properties have been investigated. The tellurides adopt a monoclinicly distorted variant (C2/m, z = 2) of the trigonal structure (P 3 bar m1, Z = 1) observed for RECuSe2 with RE = Dy, Er. The charge transport properties of RECuSe2 with RE = Pr and Sm have been also explored. While RECuTe2 display a metallic type resistivity, RECuSe2 show semiconducting properties. The room-temperature resistivities are between 0.22 and 10.5 Ω cm, with larger values observed for the selenides. Electronic structure calculations support metallic and semiconducting conductivities for the tellurides and selenides, respectively. The Seebeck coefficient indicates that the dominant charge carries are holes for all phases.

  12. Preparation, characterization, magnetic susceptibility (Eu, Gd and Sm) and XPS studies of Ln{sub 2}ZrTiO{sub 7} (Ln=La, Eu, Dy and Gd)

    SciTech Connect

    Vijaya Kumar, B.; Velchuri, Radha; Rama Devi, V.; Sreedhar, B.; Prasad, G.; Jaya Prakash, D.; Kanagaraj, M.; Arumugam, S.; Vithal, M.

    2011-02-15

    Bulk and nanosized pyrochlore materials Ln{sub 2}ZrTiO{sub 7} (Ln=La, Eu, Dy, Gd and Sm) have been prepared by the sol-gel method. All the samples were characterized by powder X-ray diffraction, Raman and X-ray photoelectron spectroscopy. Magnetic susceptibility ({chi}) measurements of Gd{sub 2}ZrTiO{sub 7}, Sm{sub 2}ZrTiO{sub 7} and Eu{sub 2}ZrTiO{sub 7} were carried out by vibrating sample magnetometer in the temperature range 2-320 K. The variation of {chi}{sup -1} (or {chi}) with temperature of Gd{sub 2}ZrTiO{sub 7}, Sm{sub 2}ZrTiO{sub 7} and Eu{sub 2}ZrTiO{sub 7} follows the Curie law, intermediate formula and the Curie-Weiss law, respectively. From the linear portion of {chi}T vs. T{sup -1} plot of Eu{sub 2}ZrTiO{sub 7} from 2 to 15 K, the classical nearest neighbor exchange (J{sup cl}) and dipolar interactions (D{sub nn}) are obtained. The XPS of Ln{sub 2}ZrTiO{sub 7} (Ln=La, Eu, Dy and Gd) gave characteristic peaks for Ln, Ti, Zr and O. The satellite peaks are observed only for 3d La of La{sub 2}ZrTiO{sub 7}. -- Graphical abstract: Sm{sub 2}ZrTiO{sub 7} does not follow the Curie or the Curie-Weiss law. The effective magnetic moment is found to be 0.768 BM (at 300 K), which is smaller than the free ion moment 1.3-1.4 BM. Display Omitted Research Highlights: {yields} Bulk and nano Ln{sub 2}ZrTiO{sub 7} (Ln=La, Eu, Dy, Gd and Sm) have been prepared by the sol-gel method. {yields} The broad Raman lines are attributed to cation disorder and small crystallite size. {yields} XPS of Ln{sub 2}ZrTiO{sub 7} exhibit characteristic X-ray photoelectron spectral features. {yields} Magnetic moment of Gd{sub 2}ZrTiO{sub 7} is obtained from magnetic susceptibility and ESR spectra.

  13. 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; Hoeppe, Henning A.

    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.

  14. Magnetic Properties of Rare-Earth Ferro- and Aluminoborates RM3(BO3)4 (M = Fe OR Al and R = Y, Gd, Er, or Dy)

    NASA Astrophysics Data System (ADS)

    Kuvandikov, O. K.; Leonyuk, N. I.; Shakarov, Kh. O.; Shodiev, Z. M.; Amonov, B. U.; Nurimov, U. É.; Sulaimonov, O. A.

    2014-04-01

    A temperature dependence of the magnetic susceptibility [χ(T)] of rare-earth borates RFe3(BO3)4 and RAl3(BO3)4 (R = Y, Gd, Er, or Dy) is measured by the Faraday method at temperatures 20-850°C. Nonlinear anomalies observed in the dependences χ-1(T) are caused by structural transitions. It is established that the dependences χ-1(T) obey a linear Curie-Weiss law for each phase. The Curie temperatures and the magnetic moments corresponding to the chemical formula unit of crystals are calculated.

  15. Studies on the new superconducting system (RE) Ba2Ca3Sr4Cu5Ox (RE=Gd, Ho & Dy)

    NASA Astrophysics Data System (ADS)

    Arumugam, S.

    1996-03-01

    Superconducting studies have been carried out in the new high TC (50-65K) system (RE)Ba2Ca3Sr4Cu5OX [(RE) 12345] with RE=Gd, Ho&Dy. The unit cell dimensions are of the order of a=5.44 °A, b=5.46°A and c=14.62°A. The data above the diamagnetic onset and below the upturn temperature due to ordering were analyzed to yield the effective magnetic moments (Peff) of the rare earth ions.

  16. {NiLn} (Ln = Gd, Dy) rod-like nano-sized heteronuclear coordination clusters with a double carbonate bridge skeleton and remarkable MCE behaviour.

    PubMed

    Guarda, Eliana; Bader, Katharina; van Slageren, Joris; Alborés, Pablo

    2016-05-17

    The newly obtained complexes [NiLn(Piv)16(teaH)6(OCH3)2(CO3)2(H2O)2] Ln = Gd, Dy, show a remarkable μ5-carbonate bridged octanuclear planar {Ni4Ln4} core further capped with embedded {Ni3Ln} cubane motifs to afford a rod shaped nano-sized molecule of about 1.2 × 2.8 nm. Unusual MCE behaviour has been found due to multiple low lying excited states arising from competing ferromagnetic and anti-ferromagnetic Ni-Ni and Ni-Ln exchange interactions. PMID:27126965

  17. Synthesis, optical properties, and energy transfer of Ce(3+)/Tb(3+) co-doped MyGdFx (M=Li, Na, K).

    PubMed

    Cao, Chunyan; Luo, Zhiyang; Guo, Siling; Cao, Renping; Noh, Hyeon Mi; Jeong, Jung Hyun; Xie, An

    2014-12-10

    Through a solid-state reaction method, the Ce(3+)/Tb(3+) co-doped MyGdFx (M=Li, Na, K; x=3, 4, 6; y=0, 1, 3) system samples have been synthesized by controlling the annealing temperatures and the ratios of raw materials. The samples were characterized by X-ray diffraction (XRD) patterns, photoluminescence (PL) excitation and emission spectra as well as luminescent dynamic decay curves. The experimental results suggest that the LiF is more difficult to react with the prepared material compared that of NaF or KF under similar reaction conditions. The samples crystallized in different crystalline phases. The energy transfer from Ce(3+) to Tb(3+) or Ce(3+) to Gd(3+) to Tb(3+) has been observed in all the samples. The Ce(3+) and Tb(3+) present different optical properties for they are sensitive to the local environment. In addition, the deduced lifetime of Tb(3+)(5)D4→(7)F5 transition decreases in the same system samples with the annealing temperature increasing. The deduced lifetime of Tb(3+)(5)D4→(7)F5 also decreases with the increase of the KF concentration in the KF system samples. PMID:24973786

  18. Difference in the luminescence properties of orthorhombic and monoclinic forms of Y{sub 2}GeO{sub 5}:Ln (Ln = Tb{sup 3+} and Dy{sup 3+})

    SciTech Connect

    Tyagi, Adish; Shah, Alpa; Sudarsan, V. Vatsa, R.K.; Jain, V.K.

    2015-04-15

    Highlights: • Improved emission colour purity with orthorhombic form of Y{sub 2}GeO{sub 5}. • Non-stationary quenching exists in orthorhombic and monoclinic forms of Y{sub 2}GeO{sub 5}:Tb. • Ion pair formation and cross relaxation quenching operating for Y{sub 2}GeO{sub 5}:Dy samples. - Abstract: The luminescence properties of Tb{sup 3+} and Dy{sup 3+} doped orthorhombic and monoclinic forms of Y{sub 2}GeO{sub 5} are significantly different. Orthorhombic Y{sub 2}GeO{sub 5} doped with Tb{sup 3+} and Dy{sup 3+} ions gives bright green and blue emission upon UV light excitation with CIE coordinates (0.25, 0.46) and (0.25, 0.24), respectively. The monoclinic Y{sub 2}GeO{sub 5} doped with these ions exhibits light green and yellowish white emissions, respectively. This has been attributed to the differences in crystallographic environments around Y{sup 3+} ions in orthorhombic and monoclinic forms of Y{sub 2}GeO{sub 5}. Quantum yield of emission for orthorhombic Y{sub 2}GeO{sub 5}:Tb (∼29%) is significantly higher than that of the monoclinic Y{sub 2}GeO{sub 5}:Tb (∼14%). Lifetime values corresponding to {sup 4}F{sub 9/2} level of Dy{sup 3+} ions in both monoclinic and orthorhombic forms of Y{sub 2}GeO{sub 5} follow an opposite trend with respect to {sup 5}D{sub 4} level of Tb{sup 3+} ions. This is attributed to difference in the concentration quenching mechanism operating for Tb{sup 3+} and Dy{sup 3+} ions.

  19. Magnetocaloric properties of TbN, DyN and HoN nanopowders prepared by the plasma arc discharge method.

    PubMed

    Shinde, K P; Jang, S H; Kim, J W; Kim, D S; Ranot, M; Chung, K C

    2015-12-21

    We report for the first time the synthesis of nanopowders of TbN, DyN and HoN crystallized in a cubic structure by the plasma arc discharge (PAD) method and investigate their magnetocaloric properties for magnetic refrigeration applications. The nitridization of terbium, dysprosium and holmium was obtained using a mixture of nitrogen and argon gas inside a discharge chamber with 4 kPa pressure. The structural and microstructural properties of these rare earth nitrides were investigated by using X-ray diffraction and transmission electron microscopy. The studied nitrides undergo a second-order ferromagnetic to paramagnetic phase transition at Curie temperatures of 35.7, 19.9 and 14.2 K for TbN, DyN and HoN, respectively. The magnetocaloric effects were estimated by calculating the magnetic entropy changes from the magnetization data sets measured at the different applied magnetic fields and temperatures. The changes in entropy -ΔSM were found to be 12.0, 13.6 and 24.5 J kg(-1) K(-1) at an applied magnetic field of 5 T. PMID:26492221

  20. Magnetic domain structure, crystal orientation, and magnetostriction of Tb0.27Dy0.73Fe1.95 solidified in various high magnetic fields

    NASA Astrophysics Data System (ADS)

    Gao, Pengfei; Liu, Tie; Dong, Meng; Yuan, Yi; Wang, Qiang

    2016-03-01

    In this paper, we studied how applying a high magnetic field during solidification of Tb0.27Dy0.73Fe1.95 alloys affected their magnetic domain structure, crystal orientation, and magnetostriction. We observed the morphology of the magnetic domain during solidification, finding it change with the applied field: from fiber like (0 T) to dot like and closure mixed (4.4 T) to fiber like (8.8 T) to fishbone like (11.5 T). The alloy solidified at 4.4 T showed the best contrast of light and dark in its domain image, widest magnetic domain, fastest magnetization, and highest magnetostriction; this alloy is followed in descending order by the alloys solidified at 11.5 T, 8.8 T, and 0 T. The orientation of the (Tb, Dy)Fe2 phase changed with magnetic field from random (0 T) to <111> (4.4 T) to <113> (8.8 T) to <110> (11.5 T). The improvement in magnetostriction was likely caused by modification of both the magnetization process and the alloy microstructure.

  1. 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

  2. Cu(II)-Gd(III) cryogenic magnetic refrigerants and Cu8Dy9 single-molecule magnet generated by in situ reactions of picolinaldehyde and acetylpyridine: experimental and theoretical study.

    PubMed

    Liu, Jun-Liang; Lin, Wei-Quan; Chen, Yan-Cong; Gómez-Coca, Silvia; Aravena, Daniel; Ruiz, Eliseo; Leng, Ji-Dong; Tong, Ming-Liang

    2013-12-16

    A series of heterometallic [Ln(III)(x)Cu(II)(y)] complexes, [Gd2Cu2]n (1), [Gd4Cu8] (2), [Ln9Cu8] (Ln=Gd, 3·Gd; Ln=Dy, 3·Dy), were successfully synthesized by a one-pot route at room temperature with three kinds of in situ carbonyl-related reactions: Cannizzaro reaction, aldol reaction, and oxidation. This strategy led to dysprosium analogues that behaved as single-molecule magnets (SMMs) and gadolinium analogues that showed significant magnetocaloric effect (MCE). In this study a numerical DFT approach is proposed by using pseudopotentials to calculate the exchange coupling constants in three polynuclear [Gd(x)Cu(y)] complexes; with these values exact diagonalization or quantum Monte Carlo simulations have been performed to calculate the variation of the magnetic entropy involved in the MCE. For the [Dy9Cu8] complexes, local magnetic properties of the Dy(III) centers have been determined by using the CASSCF+RASSI method. PMID:24265054

  3. Magnetic Ground States of the Rare-Earth Tripod Kagome Lattice Mg_{2}RE_{3}Sb_{3}O_{14} (RE=Gd,Dy,Er).

    PubMed

    Dun, Z L; Trinh, J; Li, K; Lee, M; Chen, K W; Baumbach, R; Hu, Y F; Wang, Y X; Choi, E S; Shastry, B S; Ramirez, A P; Zhou, H D

    2016-04-15

    We present the structural and magnetic properties of a new compound family, Mg_{2}RE_{3}Sb_{3}O_{14} (RE=Gd,Dy,Er), with a hitherto unstudied frustrating lattice, the "tripod kagome" structure. Susceptibility (ac, dc) and specific heat exhibit features that are understood within a simple Luttinger-Tisza-type theory. For RE=Gd, we found long-ranged order (LRO) at 1.65 K, which is consistent with a 120° structure, demonstrating the importance of diople interactions for this 2D Heisenberg system. For RE=Dy, LRO at 0.37 K is related to the "kagome spin ice" physics for a 2D system. This result shows that the tripod kagome structure accelerates the transition to LRO predicted for the related pyrochlore systems. For RE=Er, two transitions, at 80 mK and 2.1 K are observed, suggesting the importance of quantum fluctuations for this putative XY system. PMID:27127982

  4. Triple-layered perovskite niobates CaRNb3O10 (R = La, Sm, Eu, Gd, Dy, Er, Yb, or Y): new self-activated oxides.

    PubMed

    Qin, Lin; Wei, Donglei; Huang, Yanlin; Kim, Sun Il; Yu, Young Moon; Seo, Hyo Jin

    2013-09-16

    Niobates CaRNb3O10 (R = La, Sm, Eu, Gd, Dy, Er, Yb, or Y) were prepared by conventional high-temperature solid-state reaction. The formation of a single-phase compound with triple-layered perovskite-type structure was verified through X-ray diffraction (XRD) studies. The luminescence characteristics such as photoluminescence excitation and emission spectra, X-ray-excited luminescence (XEL), Stokes shift, decay curves, and color coordinates were investigated. The niobates can be efficiently excited by UV light and present luminescence behaviors with rich luminescence colors. Under excitation by ultraviolet radiation, CaRNb3O10 (R = La, Gd, Yb, or Y) exhibits strong blue luminescence due to the self-activation center of the octahedral NbO6 groups, even at room temperature. For the materials of composition CaRNb3O10 (R = Sm, Eu, Dy, or Er), the excitation at the host band produces a characteristic luminescence of rare earth ions, indicating a host-guest energy transfer process. CaRNb3O10 (R = Eu) has the strongest luminescence intensity, which can be efficiently excitated by near UV wavelength. It could be suggested to be a potential candidate for the application on near-UV excited white LEDs. PMID:23977903

  5. 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.; Varadaraju, U.V.; Raveau, B.

    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.

  6. Investigation of luminescence and laser transition of Dy3+ in Li2O-Gd2O3-Bi2O3-B2O3 glasses

    NASA Astrophysics Data System (ADS)

    Zaman, F.; Kaewkhao, J.; Srisittipokakun, N.; Wantana, N.; Kim, H. J.; Rooh, G.

    2016-05-01

    The aim of this study is to develop Li2O-Gd2O3-Bi2O3-B2O3 glass doped with different concentration of Dy3+ ions by melt quenching technique for different applications in photonics and laser devices. From the experimental oscillator strength (fexp) of the absorption spectra the JO intensity parameters (Ω λ = 2, 4, 6) have been calculated, and by using these JO intensity parameters various radiative parameters were calculated. By using JO theory the radiative transition probability (AR), radiative lifetime (τR) and branching ratio (βR) for Dy3+ ion have been found. A decrease in lifetimes of the prepared glass by increasing concentration of Dy3+ is because of the energy transfer through cross relaxation and resonant energy transfer channels in the present glass matrix. Using experimental and calculated lifetimes, the quantum efficiency (η) and non-radiative relaxation rates (WNR) of 4F9/2 excited state have been calculated. From emission spectra, effective bandwidths (Δλeff) and emission stimulated emission cross section σ (λp) were found for 4F9/2 → 6HJ (J = 15/2, 13/2, 11/2 and 9/2). Chromaticity results revealed that the CCT values of the LGBiBDy glass samples are in between to those of day light and commercial white light LED sources. Further investigations are under way for the optimization of dopant concentration in the Li2O-Gd2O3-Bi2O3-B2O3 glass.

  7. 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.

    2013-06-10

    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.

  8. 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.

  9. Influence of electron beam irradiation on the structural, electrical and thermal properties of Gd0.5Sr0.5MnO3 and Dy0.5Sr0.5MnO3 manganites

    NASA Astrophysics Data System (ADS)

    Nagaraja, B. S.; Rao, Ashok; Babu, P. D.; Sanjeev, Ganesh; Okram, G. S.

    2016-01-01

    We present systematic studies on the effect of electron beam irradiation on structural, electrical and thermal properties of Gd0.5Sr0.5MnO3 and Dy0.5Sr0.5MnO3 manganites. The XRD patterns and Rietveld analysis show that the samples remain single phased even after they undergo electron beam irradiation. Both the series of the samples Gd0.5Sr0.5MnO3 and Dy0.5Sr0.5MnO3 show insulating trends in their temperature dependent electrical resistivity, ρ(T) behavior. The resistivity data for both the series of samples (pristine as well as irradiated) indicate that the small polaron hopping model is valid in high temperature region; on contrary, variable range hopping model governs the low temperature regime. Magnetic studies demonstrate that the Neel temperatures of pristine and irradiated samples of Gd0.5Sr0.5MnO3 and Dy0.5Sr0.5MnO3 do not change appreciably when they are subjected to irradiation. Thermo-electrical power is observed to increase with irradiation in Gd0.5Sr0.5MnO3 samples, whereas for Dy0.5Sr0.5MnO3 samples a decrease in thermo-electric power is seen when the samples are irradiated.

  10. Morphotropic phase boundary and magnetoelastic behaviour in ferromagnetic Tb{sub 1−x}Gd{sub x}Fe{sub 2} system

    SciTech Connect

    Adil, Murtaza; Yang, Sen Mi, Meng; Zhou, Chao Wang, Jieqiong; Zhang, Rui; Liao, Xiaoqi; Wang, Yu; Ren, Xiaobing; Song, Xiaoping; Ren, Yang

    2015-03-30

    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 Tb{sub 1−x}Gd{sub x}Fe{sub 2} and the corresponding crystal structure, magnetic properties, and magnetostriction are explored. With the synchrotron x-ray diffractometry, the structure symmetry of TbFe{sub 2}-rich compositions is detected to be rhombohedral (R) and that of GdFe{sub 2}-rich compositions is tetragonal (T) below T{sub c}. With the change of concentration, the value of magnetostriction of the samples changes monotonously, while the MPB composition Tb{sub 0.1}Gd{sub 0.9}Fe{sub 2}, 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. The effect of complexing processes on energy transfer Tl+{r_arrow}Gd{sup 3} and Tl+{r_arrow}Tb{sup 3+} in glass

    SciTech Connect

    Belyi, M.U.; Bartnitskaya, N.E.; Mel`nik, I.F.

    1995-11-01

    The authors` studies have shown that three types of Tl{sup +} luminescence centers are formed in Tl{sup +}-activated chlorine-containing sodium-borate glass. These centers differ from one another in the number of Cl{sup -} ions contained in the first coordination sphere of Tl{sup +}. They were identified accordingly as 0-, 1-, and 2-centers of Tl{sup +}. The excitation (ES) and luminescence (LS) spectra of the 1- and 2-centers of Tl{sup +} are shifted into the region with lower energies in comparison with the spectra of 0-centers of Tl{sup +}, the LS of the 0-centers of Tl{sup +} are overlapped by the absorption spectrum (AS) of Gd{sup 3+} ions, and the LS of the 1- and 2-centers of Tl{sup +} overlaps the spectral range containing Tb{sup 3+} absorption lines. In view of the data on the overlapping of LS of Tl{sup +} ions in sodium-borate glasses by AS of REI (Gd{sup 3} and Tb{sup 3+}), one can expect effective radiationless energy transfer (RLET) Tl{sup +} {yields} Gd{sup 3+} and Tl{sup +} {yields} Tb{sup 3+}, which is an object of study in the present work.

  12. 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; Mattausch, Hansjuergen; Simon, Arndt

    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}.

  13. Synthesis and characterization of a BaGdF5:Tb glass ceramic as a nanocomposite scintillator for x-ray imaging

    NASA Astrophysics Data System (ADS)

    Lee, Gyuhyon; Struebing, Christian; Wagner, Brent; Summers, Christopher; Ding, Yong; Bryant, Alex; Thadhani, Naresh; Shedlock, Daniel; Star-Lack, Josh; Kang, Zhitao

    2016-05-01

    Transparent glass ceramics with embedded light-emitting nanocrystals show great potential as low-cost nanocomposite scintillators in comparison to single crystal and transparent ceramic scintillators. In this study, cubic structure BaGdF5:Tb nanocrystals embedded in an aluminosilicate glass matrix are reported for potential high performance MeV imaging applications. Scintillator samples with systematically varied compositions were prepared by a simple conventional melt-quenching method followed by annealing. Optical, structural and scintillation properties were characterized to guide the design and optimization of selected material systems, aiming at the development of a system with higher crystal volume and larger crystal size for improved luminosity. It is observed that enhanced scintillation performance was achieved by tuning the glass matrix composition and using GdF3 in the raw materials, which served as a nucleation agent. A 26% improvement in light output was observed from a BaGdF5:Tb glass ceramic with addition of GdF3.

  14. Synthesis and characterization of a BaGdF5:Tb glass ceramic as a nanocomposite scintillator for x-ray imaging.

    PubMed

    Lee, Gyuhyon; Struebing, Christian; Wagner, Brent; Summers, Christopher; Ding, Yong; Bryant, Alex; Thadhani, Naresh; Shedlock, Daniel; Star-Lack, Josh; Kang, Zhitao

    2016-05-20

    Transparent glass ceramics with embedded light-emitting nanocrystals show great potential as low-cost nanocomposite scintillators in comparison to single crystal and transparent ceramic scintillators. In this study, cubic structure BaGdF5:Tb nanocrystals embedded in an aluminosilicate glass matrix are reported for potential high performance MeV imaging applications. Scintillator samples with systematically varied compositions were prepared by a simple conventional melt-quenching method followed by annealing. Optical, structural and scintillation properties were characterized to guide the design and optimization of selected material systems, aiming at the development of a system with higher crystal volume and larger crystal size for improved luminosity. It is observed that enhanced scintillation performance was achieved by tuning the glass matrix composition and using GdF3 in the raw materials, which served as a nucleation agent. A 26% improvement in light output was observed from a BaGdF5:Tb glass ceramic with addition of GdF3. PMID:27044066

  15. Solvothermal synthesis of SrMoO{sub 4}:Ln (Ln = Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) nanoparticles and its photoluminescence properties at room temperature

    SciTech Connect

    Niu, Na; Yang, Piaoping; Wang, Wenxin; He, Fei; Gai, Shili; Wang, Dong; Lin, Jun

    2011-03-15

    Research highlights: {yields} A facile hydrothermal process was used to fabricate luminescent nanocrystals. {yields} The PL emissions the nanocrystals can be tuned by doping different rare-earth ions. {yields} A possible formation scheme for the as-synthesized nanocrystals was presented. -- Abstract: Rare-earth ions (Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) doped SrMoO{sub 4} nanoparticles were prepared by solvothermal route using oleic acid as surfactant to control the particle shape and size. X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), photoluminescence spectra (PL) and the kinetic decay times were applied to characterize the obtained samples. The XRD patterns reveal that all the doped samples are assigned to the scheelite-type tetragonal structure of SrMoO{sub 4} phase. In addition, the as-synthesized SrMoO{sub 4}:Ln (Ln = Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) particles are high purity well crystallized and with the average size of 30-50 nm. The possible formation process of SrMoO{sub 4}:Ln (Ln = Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) nanoparticles have been discussed as well. Upon excitation by ultraviolet radiation, the as-synthesized SrMoO{sub 4}:Ln (Ln = Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) nanoparticles exhibit the characteristic emission lines of corresponding Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+}, respectively.

  16. Spin-Phonon and Electron-Phonon Interactions in Multiferroic GdFe3 (BO3)4 and TbFe3 (BO3)4 Evidenced by IR Reflection Spectroscopy

    NASA Astrophysics Data System (ADS)

    Klimin, S. A.; Kashchenko, M. A.; Bezmaternykh, L. N.

    2016-03-01

    We study temperature-dependent polarized reflection spectra of multiferroic GdFe3 (BO3)4 and TbFe3 (BO3)4 single crystals. Signatures of spin-lattice interactions in both compounds and of a formation of the electron-phonon coupled mode in TbFe3 (BO3)4 are discussed.

  17. Synthesis of SrAl2O4:Eu2+ phosphors co-doped with Dy3+, Tb3+, Si4+ and optimization of co-doping amount by response surface method

    NASA Astrophysics Data System (ADS)

    Wang, Huan; Liang, Xiaoping; Liu, Kai; Zhou, Qianqian; Chen, Peng; Wang, Jun; Li, Jianxin

    2016-03-01

    Dy3+ doped SrAl2O4:Eu2+ phosphors were synthesized by high temperature solid phase method in a weak reducing atmosphere (5% H2 + 95% N2). The relationship between the crushed granularity and the phosphors brightness was studied. The effect of co-doping amount of Dy3+, Tb3+ and Si4+ on the structure and properties of SrAl2O4:Eu2+ via response surface method was investigated. Photoluminescence measurement results showed that the initial afterglow brightness of 0.002 mol% Dy3+ doped SrAl2O4:Eu2+0.002 phosphors decreased after first increased within the sintering temperature range from 1150 to 1400 °C, which created the highest value of 12,101 mcd/m2 at 1300 °C. Numerous coarse particles in the powder ought to be crushed for the practical application, however, the brightness became lower accompanied by the decrease of the granularity. The luminescence property of SrAl2O4:Eu2+ sintered at 1200 °C improved by co-doping Dy3+-Tb3+-Si4+. The results of response surface method showed that the influence extent on the luminescence property was Dy3+ > Tb3+ > Si4+. When the co-doping amount in SrAl2O4:Eu2+0.002 phosphors of Dy3+, Tb3+ and Si4+ was 0.001 mol%, 0.0005 mol% and 0.002 mol%, respectively, the initial afterglow brightness of SrAl2O4 was up to the highest value of 12,231 mcd/m2, which was in good agreement on the predicted maximum value of 12,519 mcd/m2 with the optimum co-doping amount of 0.0015 mol% Dy3+, 0.0005 mol% Tb3+ and 0.0017 mol% Si4+. The brightness of co-doped phosphors not only increased by 56.79% than that of SrAl2O4:Eu2+0.002, Dy3+0.002 sintered at 1200 °C, but also was above that of 1300 °C. The emission spectra results showed that, compared with 0.001 mol% Dy3+ doped phosphor, the emission peak of 0.001 mol% Dy3+-0.001 mol% Tb3+ co-doped phosphor generated red shift and increased by 9.3% in emission intensity; 0.001 mol% Dy3+-0.004 mol% Si4+ and 0.001 mol% Dy3+-0.001 mol% Tb3+-0.004 mol% Si4+ co-doped SrAl2O4:Eu2+0.002 emission peak created blue shift and increased by 37.2% and 47.6% in emission intensity, respectively.

  18. Luminescence properties of long persistent phosphors BaZrSi3O9:R3+ (R = Eu, Sm, Dy, Tb and Pr) based on host sensitization

    NASA Astrophysics Data System (ADS)

    Jin, Yahong; Hu, Yihua; Chen, Li; Wang, Xiaojuan

    2014-09-01

    Undoped and R3+ ions (R = Eu, Sm, Dy, Tb and Pr) singly doped BaZrSi3O9 phosphors were synthesized by a traditional solid state reaction method. All samples were studied by X-ray diffraction, photoluminescence spectra, afterglow decay curves, long persistent luminescence (LPL) spectra and thermoluminescence (TL) glow curves. The different characteristic emissions and LPL from these R3+ ions were obtained by the same UV excitation. These phenomena were derived from the energy transfer that originates from BaZrSi3O9 host. The nature of trapping centers was studied with TL glow curves. The incorporation of R3+ ions into host lattice produced some new traps. Accordingly, the mechanism of long afterglow in BaZrSi3O9:R3+ was also discussed.

  19. Simple correction for the sample shape and radial offset effects on SQUID magnetometers: Magnetic measurements on Ln2O3 (Ln=Gd, Dy, Er) standards

    NASA Astrophysics Data System (ADS)

    Morrison, Gregory; zur Loye, Hans-Conrad

    2015-01-01

    An increased focus on magnetic measurements of oriented single crystals, thin films, and magnetically dilute systems has led to a demand for the measurement of weak magnetic moments. This level of sensitivity and precision can be achieved on SQUID magnetometers by decreasing the size of the detection coils. However, the smaller detection coils can amplify two errors in the magnitude of the measured moment, the sample shape and radial offset effects, which were small and typically unaccounted for on previous magnetometers. We report a simple method to determine the radial offset of a sample by taking advantage of the two basic scan modes, DC and lock-in, typically used on magnetometers. This technique allows for the correction of the sample shape and radial offset effects in order to obtain the true moment of a sample. To show the efficacy of this technique, we report the magnetic properties of Ln2O3 (Ln=Gd, Dy, Er).

  20. Heat capacities, magnetic properties, and resistivities of ternary RPdBi alloys where R = La, Nd, Gd, Dy, Er, and Lu

    SciTech Connect

    Riedemann, T.M.

    1996-05-01

    Over the past four and a half decades research on the rare earths, their compounds, and their alloys has yielded significant insights into the nature of materials. The rare earths can be used to systematically study a series of alloys or compounds. Magnetic ordering, crystalline fields, spin fluctuations, the magnetocaloric effect, and magnetostriction are a small sample of phenomena studied that are exhibited by the rare earth family. A significant portion of research has been conducted on the abundant RM{sub 2} and RM phases, where R is the rare earth and M is a transition metal. The natural progression of science has led to the study of related RMX ternary phases, where X is either another transition metal or semimetal. There are now over 1,000 known RMX phases. The focus of this study is on RPdBi where R = La, Nd, Gd, Dy, Er, and Lu. Their heat capacities, magnetic properties, and resistivities are studied.

  1. A ? and neutron scattering study of ?, where RE = Ce, Nd, Gd and Tb

    NASA Astrophysics Data System (ADS)

    Lidström, Erik; Wäppling, Roger; Hartmann, Ola; Ekström, Mikael; Kalvius, G. M.

    1996-08-01

    The 0953-8984/8/34/016/img10 series presents varied magnetic ordering behaviour within compounds that are structurally identical except for slight differences in lattice parameters. The compounds are quasi-two-dimensional and order at temperatures between 1.7 and 20 K. The two magnetic structures of 0953-8984/8/34/016/img11 have been refined and the results compared to a previously unpublished magnetic neutron diffraction study of most of the series. All four compounds in this study have been examined using zero-field and longitudinal-field 0953-8984/8/34/016/img12. In 0953-8984/8/34/016/img13 and 0953-8984/8/34/016/img14 a systematic build-up of magnetic correlations occurs as the magnetic ordering temperature is approached, while in the Gd compound no increase of magnetic correlations is observed within the experimental resolution of 0.1 K. In 0953-8984/8/34/016/img15, a linear increase is observed in a log - log diagram of the muon depolarization rate as the temperature is decreased from 30 times the ordering temperature towards 0953-8984/8/34/016/img16. In three of the compounds (0953-8984/8/34/016/img17 and 0953-8984/8/34/016/img14), two distinct muon sites are observed. The exponents for the damping as a function of the reduced temperature are found to be dependent on the muon site, especially in 0953-8984/8/34/016/img14 where the signals from the two different sites can be best separated.

  2. 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; Zhang Lili; Zhong Hui; Lu Lude; Yang Xujie; Wang Xin

    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.

  3. Completing the series of +2 ions for the lanthanide elements: synthesis of molecular complexes of Pr2+, Gd2+, Tb2+, and Lu2+.

    PubMed

    MacDonald, Matthew R; Bates, Jefferson E; Ziller, Joseph W; Furche, Filipp; Evans, William J

    2013-07-01

    The first examples of crystallographically characterizable complexes of Tb(2+), Pr(2+), Gd(2+), and Lu(2+) have been isolated, which demonstrate that Ln(2+) ions are accessible in soluble molecules for all of the lanthanides except radioactive promethium. The first molecular Tb(2+) complexes have been obtained from the reaction of Cp'3Ln (Cp' = C5H4SiMe3, Ln = rare earth) with potassium in the presence of 18-crown-6 in Et2O at -35 °C under argon: [(18-crown-6)K][Cp'3Tb], {[(18-crown-6)K][Cp'3Tb]}n, and {[K(18-crown-6)]2(μ-Cp')}{Cp'3Tb}. The first complex is analogous to previously isolated Y(2+), Ho(2+), and Er(2+) complexes, the second complex shows an isomeric structural form of these Ln(2+) complexes, and the third complex shows that [(18-crown-6)K](1+) alone is not the only cation that will stabilize these reactive Ln(2+) species, a result that led to further exploration of cation variants. With 2.2.2-cryptand in place of 18-crown-6 in the Cp'3Ln/K reaction, a more stable complex of Tb(2+) was produced as well as more stable Y(2+), Ho(2+), and Er(2+) analogs: [K(2.2.2-cryptand)][Cp'3Ln]. Exploration of this 2.2.2-cryptand-based reaction with the remaining lanthanides for which Ln(2+) had not been observed in molecular species provided crystalline Pr(2+), Gd(2+), and Lu(2+) complexes. These Ln(2+) complexes, [K(2.2.2-cryptand)][Cp'3Ln] (Ln = Y, Pr, Gd, Tb, Ho, Er, Lu), all have similar UV-vis spectra and exhibit Ln-C(Cp') bond distances that are ~0.03 Å longer than those in the Ln(3+) precursors, Cp'3Ln. These data, as well as density functional theory calculations and EPR spectra, suggest that a 4f(n)5d(1) description of the electron configuration in these Ln(2+) ions is more appropriate than 4f(n+1). PMID:23697603

  4. Magnetic and magnetotransport behavior of R F e5A l7(R =Gd and Dy ) : Observation of reentrant inverse-magnetocaloric phenomenon and asymmetric magnetoresistance behavior

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    We have compared and contrasted magnetic, magnetocaloric, and magnetoresistive properties of Gd and Dy members of the rare-earth (R ) series R F e5A l7 , crystallizing in ThM n12 structure, known to order antiferromagnetically. Among other observations, we would like to emphasize the following findings: (i) There are multiple sign crossovers in the temperature (T ) dependence of isothermal entropy change (Δ S ) in the case of Dy compound. In addition to nil Δ S at the magnetic compensation point known for two-magnetic-sublattice systems, there is an additional sign crossover at low temperatures, as though there is a "reentrant inverse-magnetocaloric" phenomenon. Corresponding sign reversals could also be observed in the magnetoresistance data. (ii) The plots of magnetoresistance versus magnetic field are found to be highly asymmetric with the reversal of the direction of magnetic field (H ) well below TN for both compounds, similar to those known for antiferromagnetic tunnel junctions. We attribute these to subtle changes in spin orientations of R and Fe moments induced by T and H .

  5. Quaternary rare-earth arsenides REAg1-xZnyAs2 (RE=La-Nd, Sm, Gd-Dy) with tetragonal SrZnBi2- and HfCuSi2-type structures

    NASA Astrophysics Data System (ADS)

    Ramachandran, Krishna K.; Genet, Clément; Mar, Arthur

    2015-11-01

    Reactions of the elements at 800 °C with the nominal compositions REAg1-xZnxAs2 resulted in quaternary arsenides REAg1-xZnyAs2 in which the combined Ag and Zn content deviates increasingly from unity in the Zn-richer phases, reflecting the transition from the fully stoichiometric ternary silver-containing arsenides REAgAs2 to the substoichiometric zinc-containing ones REZn0.67As2. Powder X-ray diffraction analysis indicated SrZnBi2-type (space group I4/mmm, Z=4; RE=La, Ce) and HfCuSi2-type structures (space group P4/nmm, Z=2; RE=Pr, Nd, Sm, Gd, Tb, Dy). Single-crystal X-ray diffraction analysis performed on LaAg0.5Zn0.5As2, PrAg0.5Zn0.5As2, and NdAg0.5Zn0.5As2 indicated that the Ag and Zn atoms are disordered within metal-centred tetrahedra and provided no evidence for distortion of the square As nets. The small electron excess tolerated in these quaternary arsenides and the absence of distortion in the square nets can be traced to the occurrence of As-As states that are only weakly antibonding near the Fermi level. PrAg0.5Zn0.5As2 and NdAg0.5Zn0.5As2 are paramagnetic with effective magnetic moments consistent with trivalent RE species.

  6. Optical and relaxometric properties of monometallic (Eu(III), Tb(III), Gd(III)) and heterobimetallic (Re(I)/Gd(III)) systems based on a functionalized bipyridine-containing acyclic ligand.

    PubMed

    Leygue, Nadine; Boulay, Alexandre; Galaup, Chantal; Benoist, Eric; Laurent, Sophie; Vander Elst, Luce; Mestre-Voegtlé, Béatrice; Picard, Claude

    2016-05-17

    A series of lanthanide complexes of [LnL(H2O)](2-) composition where Ln = Eu(III), Tb(III) or Gd(III) has been studied for determining their photophysical and relaxometric properties in aqueous solution. The bifunctional ligand L (H5BPMNTA) is an acyclic chelator based on a central functionalized 2,2'-bipyridine core and two iminodiacetate coordinating arms. The mono-aqua Eu(III) and Tb(III) complexes display attractive spectroscopic properties with an excitation wavelength at 316 nm, similar excited state lifetimes and overall quantum yields (in the ranges 0.5-0.6 ms and 10-13%, respectively) in Tris buffer (pH 7.4). The proton longitudinal relaxivity, r1, of the Gd(III) complex is 4.4 mM(-1) s(-1) at 20 MHz and 310 K, which is comparable to that of the clinically used Gd-DTPA (Magnevist®). Interestingly, the water exchange rate between the coordination site and the bulk solvent is very fast (Kex = 2.6 × 10(8) s(-1) at 310 K). The ability of the complex to bind non-covalently to human serum albumin (HSA) was also examined by relaxometric measurements. We also report the synthesis and properties of a bimetallic complex based on Gd-BPMNTA and Re(I)(bpy)(CO)3 components. In this system, the Re core exhibits interesting photophysical properties (λem = 588 nm, Φ = 1.4%) and the Gd-BPMNTA core displays improved relaxivity (r1 = 6.6 mM(-1) s(-1) at 20 MHz and 310 K), due to an increase of the rotational correlation time. Besides these appealing optical and relaxometric properties, the presence of a reactive function on the structure proposes this potential dual imaging probe for conjugation to biomolecules or nanomaterials. PMID:27109253

  7. Ternary rare earth metal boride carbides containing two-dimensional boron-carbon network: The crystal and electronic structure of R{sub 2}B{sub 4}C (R=Tb, Dy, Ho, Er)

    SciTech Connect

    Babizhetskyy, Volodymyr Zheng Chong; Mattausch, Hansjuergen; Simon, Arndt

    2007-12-15

    The ternary rare earth boride carbides R{sub 2}B{sub 4}C (R=Tb, Dy, Ho, Er) have been synthesized by reacting the elements at temperatures between 1800 and 2000K. The crystal structure of Dy{sub 2}B{sub 4}C has been determined from single-crystal X-ray diffraction data. It crystallizes in a new structure type in the orthorhombic space group Immm (a=3.2772(6) A, b=6.567(2) A, c=7.542(1) A, Z=2, R1=0.035 (wR{sub 2}=0.10) for 224 reflections with I{sub o}>2{sigma}(I{sub o})). Boron atoms form infinite chains of fused B{sub 6} rings in [100] joined with carbon atoms into planar, two-dimensional networks which alternate with planar sheets of rare earth metal atoms. The electronic structure of Dy{sub 2}B{sub 4}C was also analyzed using the tight-binding extended Hueckel method. - Graphical abstract: Dy{sub 2}B{sub 4}C crystallizes a new structure type where planar 6{sup 3}-Dy metal atom layers alternate with planar non-metal layers consisting of ribbons of fused B{sub 6} hexagons bridged by carbon atoms. Isostructural analogues with Tb, Ho and Er have also been characterized.

  8. Novel Dy{sup 3+}-doped Ca{sub 2}Gd{sub 8}(SiO{sub 4}){sub 6}O{sub 2} white light phosphors for Hg-free lamps application

    SciTech Connect

    Wang, Yuhua; Wen, Yan; Zhang, Feng

    2010-11-15

    The luminescent properties of Ca{sub 2}Gd{sub 8(1-x)}(SiO{sub 4}){sub 6}O{sub 2}:xDy{sup 3+} (1% {<=} x {<=} 5%) powder crystals with oxyapatite structure were investigated under vacuum ultraviolet excitation. In the excitation spectrum, the peaks at 166 nm and 191 nm of the vacuum ultraviolet region can be assigned to the O{sup 2-} {yields} Gd{sup 3+}, and O{sup 2-} {yields} Dy{sup 3+} charge transfer band respectively, which is consistent with the theoretical calculated value using J{phi}rgensen's empirical formula. While the peaks at 183 nm and 289 nm are attributed to the f-d spin-allowed transitions and the f-d spin-forbidden transitions of Dy{sup 3+} in the host lattice with Dorenbos's expression. According to the emission spectra, all the samples exhibited excellent white emission under 172 nm excitation and the best calculated chromaticity coordinate was 0.335, 0.338, which indicates that the Ca{sub 2}Gd{sub 8}(SiO{sub 4}){sub 6}O{sub 2}:Dy{sup 3+} phosphor could be considered as a potential candidate for Hg-free lamps application.

  9. 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 (ε) and tangent loss (tan δ)) 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.

  10. Manifestation of π-π stacking interactions in luminescence properties and energy transfer in aromatically-derived Tb, Eu and Gd tris(pyrazolyl)borate complexes.

    PubMed

    Mikhalyova, Elena A; Yakovenko, Anastasiya V; Zeller, Matthias; Kiskin, Mikhail A; Kolomzarov, Yuriy V; Eremenko, Igor L; Addison, Anthony W; Pavlishchuk, Vitaly V

    2015-04-01

    The three new complexes Tp(Py)Ln(CH3CO2)2(H2O) (Ln = Eu (1), Gd(2), or Tb (3)) were prepared and characterized crystallographically. In the crystal lattices of these complexes, separate molecules are connected in infinite chains by π-stacking interactions. Complexes 1 and 3 display intense photoluminescence and triboluminescence (red and green respectively), while compound 3 exhibits electroluminescence commencing at 9 V in an ITO/PVK/3/Al device (ITO = indium-tin oxide, PVK = poly(N-vinylcarbazole)). A series of Eu/Tb-doped Gd compounds was prepared by cocrystallization from mixtures of 1 and 2 or 2 and 3, respectively. It was shown that π-stacking interactions are involved in increasing the efficiency of energy transfer from the gadolinium complex to emitting [Tp(Py)Eu](2+) or [Tp(Py)Tb](2+) centers, and this energy transfer occurs through hundreds of molecules, resembling the process of energy harvesting in chloroplast stacks. PMID:25797500

  11. Transport properties in amorphous U/sub x/-T/sub 1//sub -//sub x/ films (T = Fe, Ni, Gd, Tb, and Yb) (invited)

    SciTech Connect

    Freitas, P.P.; Plaskett, T.S.; Moreira, J.M.; Amaral, V.S.

    1988-11-15

    We describe the competing magnetic, localization, and phonon effects on the transport properties of amorphous magnetic U/sub x/T/sub 1-//sub x/ films, with T = Fe, Ni, Gd, Tb, and Yb. Amorphous U/sub x/Fe/sub 1-//sub x/ films change from collinear to random ferromagnetism as x increases, and the temperature dependence of the resistivity denotes the competing effects of spin-flip and non-spin-flip exchange scattering processes. The resistivity has a minimum at T/sub f/ rising sharply below this temperature. The sign of the magnetic resistivity and the magnetoresistance indicates >0, while the anisotropic magnetoresistance indicates a local exchange gap. Amorphous U/sub x/Gd/sub 1-//sub x/ and a-U/sub x/Tb/sub 1-//sub x/ are, respectively, spin glasses and random anisotropy dominated systems. The resistivity increases smoothly through T/sub f/ and has a slight upturn at low temperatures that we associate with weak localization. The magnetoresistance is negative in both systems and the anisotropic magnetoresistance is null, although the applied field induces anisotropic behavior in the Tb containing films (asperomagnets). All samples show quadratic and positive field dependence of magnetoresistance well inside the paramagnetic regime, and a linear regime below T/sub f/. At low temperatures and in the a-U/sub x/Gd/sub 1-//sub x/ films, negative (H)/sup 1/2/ and H/sup 2/ regimes occur and are associated with weak localization processes dominated by the inelastic mean free path.

  12. 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.

  13. Luminescence and energy transfer of the color-tunable phosphor Li6Gd(BO3)3:Tb(3+)/Bi(3+), Eu(3.).

    PubMed

    Chen, Peican; Mo, Fuwang; Guan, Anxiang; Wang, Rongfang; Wang, Guofang; Xia, Siyu; Zhou, Liya

    2016-02-01

    Bi(3+)/Tb(3+), Eu(3+) co-doped Li6Gd(BO3)3 (LGBO) phosphors were synthesized via a traditional solid-state method. Phase purity was investigated using X-ray diffraction, absorption strength of the phosphors were investigated by UV-vis absorption spectra, and the photoluminescence properties of the phosphors were studied systematically. Results showed that the emission intensity of Bi(3+), Eu(3+) co-doped LBOG was 2.76 times higher than that of Eu(3+)-doped LGBO irradiated at 275nm, thereby implying the possibility of energy transfer from Bi(3+) to Eu(3+). The excitation spectra of Tb(3+), Eu(3+) co-doped LGBO phosphors are broader in comparison with single-doped phosphors and show tunable colors from green to yellow to orange-red when the ratio of Tb(3+) to Eu(3+) is adjusted These results demonstrate that LGBO:Tb(3+), Eu(3+) phosphors have potential use in light-emitting diodes. PMID:26720264

  14. Ternary rare earth metal boride carbides containing two-dimensional boron carbon network: The crystal and electronic structure of R2B4C (R=Tb, Dy, Ho, Er)

    NASA Astrophysics Data System (ADS)

    Babizhetskyy, Volodymyr; Zheng, Chong; Mattausch, Hansjürgen; Simon, Arndt

    2007-12-01

    The ternary rare earth boride carbides R2B4C (R=Tb, Dy, Ho, Er) have been synthesized by reacting the elements at temperatures between 1800 and 2000K. The crystal structure of Dy2B4C has been determined from single-crystal X-ray diffraction data. It crystallizes in a new structure type in the orthorhombic space group Immm (a=3.2772(6) Å, b=6.567(2) Å, c=7.542(1) Å, Z=2, R1=0.035 (wR2=0.10) for 224 reflections with Io>2σ(Io)). Boron atoms form infinite chains of fused B6 rings in [100] joined with carbon atoms into planar, two-dimensional networks which alternate with planar sheets of rare earth metal atoms. The electronic structure of Dy2B4C was also analyzed using the tight-binding extended Hückel method.

  15. A magnetic, magnetostrictive and Mössbauer study of Tb 0.3Dy 0.7-xPr x(Fe 0.9Al 0.1) 1.95 alloys

    NASA Astrophysics Data System (ADS)

    Zheng, Xiaoping; Zhang, Peifeng; Li, Fashen; Cheng, Zhaohua; Shen, Baogen

    2009-12-01

    The effect of Pr substitution for Dy on the magnetization, magnetostriction, anisotropy and spin reorientation of a series of Tb 0.3Dy 0.7-xPr x(Fe 0.9Al 0.1) 1.95 alloys ( x=0, 0.1, 0.20, 0.25, 0.30, 0.35) at room temperature has been investigated. It was found that the magnetization and magnetostriction of the homogenized Tb 0.3Dy 0.7-xPr x(Fe 0.9Al 0.1) 1.95 alloys decreases drastically with increasing x and the magnetostrictive effect disappears for x>0.2, but the spontaneous magnetostriction λ111 increases approximately linearly with increasing x. Moreover, the magnetostriction exhibits slightly bigger value at x=0.1 than the free alloys and is saturated more easily with the magnetic field H, showing that a small amount of Pr substitution is beneficial to a decrease in the magnetocrystalline anisotropy. The analysis of the Mössbauer spectra indicated that the easy magnetization direction in the {1 1 0} plane deviates slightly from the main axis of symmetry with Pr concentration x, namely spin reorientation. Comparing with the Al substitution, the effect of Pr substitution for Dy on the spin reorientation is smaller.

  16. Decay studies of neutron-deficient nuclei near the Z=64 subshell: 141Dy, 141Tb, 141Gdg+m, and 141Eum

    NASA Astrophysics Data System (ADS)

    Gilat, J.; Nitschke, J. M.; Wilmarth, P. A.; Firestone, R. B.

    1989-11-01

    The β/γ and delayed proton decays of mass separated A=141 isotopes with Z=63-66 were investigated with an on-line mass separator. Branching ratios have been redetermined for the total β decay of the 2.7(3) s, (11/2- isomer 141Eum at 96.5 keV (13+4-2%), and for the direct β feeding of the 1.58 keV (3/2+ level of 141Sm in the decay of 40-s 141Eug [73(5)%]. Detailed decay schemes have been constructed for the decays of the (11/2- isomer 141Gdm [11(2)% isomeric transition] and the (1/2+ ground state, 141Gdg. Half-lives of 24.5(5) s and 14(4) s, respectively, have been determined for these isomers. A delayed proton branch of 0.03(1)% was identified in the decay of 141Gdg. A detailed decay scheme was also constructed for 3.5(2)-s 141Tb and a Jπ=(5/2- was assigned to its ground state, at variance with the systematics of heavier, odd-mass Tb isotopes. All γ-ray assignments to the various isotopes are based on xγ and γγ coincidences and on half-life measurements. A 0.9(2)-s half-life for 141Dy was determined from its delayed proton decay. All spin assignments proposed in this paper are discussed in terms of Nilsson level diagrams and nuclear shapes.

  17. 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.

  18. Facile template free synthesis of Gd2O(CO3)2·H2O chrysanthemum-like nanoflowers and luminescence properties of corresponding Gd2O3:RE3+ spheres.

    PubMed

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

    2013-08-28

    Trivalent rare-earth (RE(3+) = Eu(3+), Tb(3+), Dy(3+), and Sm(3+)) ions activated Gd2O(CO3)2·H2O chrysanthemum-like flowers are prepared by a modified urea-based homogeneous precipitation via a template free hydrothermal synthesis route. Subsequently, Gd2O3 monodispersed spheres were obtained after calcining at 750 °C. The growth mechanism of the Gd2O(CO3)2·H2O:RE(3+) chrysanthemum-like morphology (homogeneous precipitation) and their transformation to monodispersed spheres (heterogeneous nucleation) are established by taking scanning electron microscope and transmission electron microscope images of the intermediate products. The thermogravimetric analysis, Fourier transform infrared analyses confirmed the decomposition of CO2 and OH groups, and the corresponding XRD patterns exhibited the Gd2O(CO3)2·H2O and cubic Gd2O3 phases. The photoluminescence measurements are used to explore the emission behavior of different RE(3+) ions activated Gd2O3 spheres. The Gd2O3:Eu(3+) shows gorgeous red emission with high purity red color as compared to the commercial Y2O3:Eu(3+) phosphors. Gd2O3:Tb(3+), Gd2O3:Dy(3+) and Gd2O3:Sm(3+) exhibit green, yellow and rich orange emissions, respectively. The Tb(3+)/Eu(3+) co-doped sample shows warm white light by controlling the energy transfer. At minimal parameters, the cathodoluminescence intensity of Gd2O3:Eu(3+) is beyond the experimental limit for 5 kV of accelerating voltage. The CIE chromaticity coordinates were also calculated from the PL and CL spectra of RE(3+) ions to establish their color richness. PMID:23817306

  19. 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.; Rao, C.N.R.

    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.

  20. Preparation and Dielectric Measurements of the Rare Earth Green Phases R2BaCuO(5-x) (R = Y, Sm, Gd, Dy, Ho, Er, Yb)

    NASA Technical Reports Server (NTRS)

    Gonzalez-Titman, Carlos

    1994-01-01

    It has been demonstrated that R2BaCuO(5-x) (R = Y, Sm, Gd, Dy, Ho, Er, Yb) does not undergo significant densification unless the sintering temperatures are near the incongruent melting point or the sintering times are long. Good quality powders of Y2BaCuO(5-x) have been synthesized by using oxide raw materials or precursors such as acetates and nitrates. The acetates- and the nitrates-derived yttrium green phase resulted in finer particle sizes, acceptable dielectric properties and lower melting temperatures than those processed via oxide raw materials. The hot pressing technique has been employed to produce a dense R2BaCuO(5-x) (R=Y,Gd) substrate with satisfactory dielectric properties. Reactivity to reducing conditions, i.e. graphite die, limited the optimization of the properties. A high sensitivity to the annealing atmosphere has been demonstrated in Y2BaCuO,.,,. Oxygen treatment at 950 OC has been shown to improve the dielectric properties while treatment in nitrogen, at the same temperature, degraded desirable properties. A high sensitivity to the annealing atmosphere has been demonstrated in Y2BaCuO(5-x). Oxygen treatment at 950 C has been shown to improve the dielectric properties while treatment in nitrogen, at the same temperature, degraded desirable properties. The dielectric constants of the rare earth green phases R2BaCuO(5-x) were found to be low. Relaxation peaks were detected at low temperatures (T less than 150 K) and at high temperatures (150 less than T greater than 420 K). The dielectric losses and conductivities at 77 K were measured to be in the range of 10(exp -4) and 10(exp -12) (Omega-cm)(exp -1), respectively. Many parameters were found to exhibit dependencies on the rare earth cation sizes.

  1. Octanuclear Mn(III)6Mn(II)Ln (Ln = Gd, Dy and Er) clusters with a novel core topology: syntheses, structures, and magnetic properties.

    PubMed

    Chen, Hui; Ma, Cheng-Bing; Hu, Ming-Qiang; Wen, Hui-Min; Cui, Hong-Hua; Liu, Jin-Ying; Song, Xiao-Wei; Chen, Chang-Neng

    2013-04-14

    Reactions of [Mn6O2(piv)10(py)2.5(piv)1.5], Ln(NO3)3·6H2O and N-mdeaH2 in MeCN in the presence of Me3SiCl generated a family of octanuclear Mn/Ln complexes [Mn6(III)Mn(II)Ln(N-mdea)3(N-mdeaH)(piv)8O2(OH)3(NO3)(H2O)]·xCH3CN·xH2O [Ln = Gd (1), Dy (2), Er (3), pivH = pivalic acid, N-mdeaH2 = N-methyl diethanolamine]. Each complex possesses a [Mn6(III)Mn(II)Ln(μ3-O)2(μ3-OH)3](16+) core containing two butterfly-like subunits of [Mn3Ln(μ3-OH)2] and [Mn4(μ3-O)2] sharing a common vertex, and an outer Mn atom ligated to one of the subunits through a μ3-OH(-) ligand. The core topology represents a new Mn/Ln core type. The magnetic susceptibility study of 1-3 indicates the presence of dominant antiferromagnetic interactions within the complexes. For complex 1, which contains an isotropic Gd(III) atom, fitting of the obtained M/(NμB) vs. H/T data gave S = 4, g = 1.90, and D = -0.31 cm(-1). The results were further supported by ac data. Complex exhibits out-of-phase ac susceptibility signals, indicating it may be a SMM. PMID:23377042

  2. Fabrication and evaluation of a Gd2O2S:Tb phosphor screen film for development of a CMOS-based X-ray imaging detector

    NASA Astrophysics Data System (ADS)

    Park, Ji Koon; Choi, Su Rim; Noh, Si Cheol; Jung, Bong Jae; Choi, Il Hong; Kang, Sang Sik

    2014-08-01

    In this study, Gd2O2S:Tb phosphor screen films were fabricated by using a special particle-inbinder sedimentation method. The phosphor particles used in this study were manufactured in two sizes, 2.5- μm and 5- μm. To evaluate luminescence efficiency and the spatial resolution according to the thickness, we fabricated screen films with thicknesses of 120, 150, 170, and 210- μm. The spatial resolution of the fabricated films was assessed by using an edge method to measure the modulation transfer function (MTF). From the experimental results, the spatial resolution of the mammography exposures (low-energy X-ray quality) was better than that of dental radiography (high-energy X-ray quality). Also, with the same film thickness, the screen with 2.5- μm particles had better resolution than the screen with 5.0- μm particles, but it showed about 20% lower resolution than a commercial Gd2O2S:Tb screen. In the evaluation of the results for the dependence of the spatial resolution on the film's thickness, the 120- μm-thick screen showed the highest resolution, which was similar to that of a commercial screen.

  3. Magnetoelectric properties of Tb0.3Dy0.7Fe1.92/Pb(Zr x Ti1- x )O3 bilayer thin films

    NASA Astrophysics Data System (ADS)

    Hwang, Sung-Ok; Koo, Chang Young; Lee, Jai-Yeoul; Lee, Hee Young; Ryu, Jungho; Kim, Jong-Woo

    2013-12-01

    Magnetoelectric Tb0.3Dy0.7Fe1.92(Terfenol-D)/PbZr x Ti1- x O3(PZT) bilayer thin films were deposited on (111)-oriented Pt/Ti/SiO2/Si< 100 > substrates. The PZT layers with different compositions ( x = 0.3 and 0.52) were grown on the substrates by using the sol-gel method. Terfenol-D layers were deposited on the PZT-film-coated substrate by ion beam sputtering at room temperature with a dot-type patterned metal shadow mask. The structural characteristics and the ferroelectric, ferromagnetic and magnetoelectric(ME) properties of the Terfenol-D/PZT bilayer thin films were investigated. In our results, the maximum remnant polarization, 2 P r were ˜60 µC/cm2 for Terfenol-D/PZT(30/70) (Zr/Ti ratio = 30/70). The magnetization and the ME voltage coefficients were identical regardless of the Zr/Ti composition of PZT. The ME voltage coefficients of the films were over 400 mV/cm·Oe, which were about 4 times higher than the values reported for other bilayer structures.

  4. Determination of the exchange constant of Tb0.3Dy0.7Fe2 by broadband ferromagnetic resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Gopman, D. B.; Lau, J. W.; Mohanchandra, K. P.; Wetzlar, K.; Carman, G. P.

    2016-02-01

    We present measurements of the exchange stiffness D and the exchange constant A of a sputtered 80 nm Tb0.3Dy0.7Fe2 film. Using a broadband ferromagnetic resonance setup in a wide frequency range from 10 to 50 GHz, multiple perpendicular standing spin-wave resonances were observed with the external static magnetic field applied in-plane. The field corresponding to the strongest resonance peak at each frequency is used to determine the effective magnetization, the g factor, and the Gilbert damping. Furthermore, the dependence of spin-wave mode on field position is observed for several frequencies. The analysis of spin-wave resonance spectra at multiple frequencies allows precise determination of the exchange stiffness D =(2.79 ±0.02 )×10-17T m2 for an 80 nm thick film. From this value, we calculated the exchange constant A =(9.1 ±0.1 ) pJ m-1 .

  5. Structural and optical properties of lanthanide oxides grown by atomic layer deposition (Ln = Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb).

    PubMed

    Hansen, Per-Anders; Fjellvåg, Helmer; Finstad, Terje; Nilsen, Ola

    2013-08-14

    Ln2O3 thin films with optically active f-electrons (Ln = Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb) have been grown on Si(100) and soda lime glass substrates by atomic layer deposition (ALD) using Ln(thd)3 (Hthd = 2,2,6,6-tetramethyl-3,5-heptanedione) and ozone as precursors. The temperature range for depositions was 200-400 °C. Growth rates were measured by spectroscopic ellipsometry and a region with a constant growth rate (ALD window) was found for Ln = Ho and Tm. All the compounds are grown as amorphous films at low temperatures, whereas crystalline films (cubic C-Ln2O3) are obtained above a certain temperature ranging from 300 to 250 °C for Nd2O3 to Yb2O3, respectively. AFM studies show that the films were smooth (rms < 1 nm) except for depositions at the highest temperatures. The refractive index was measured by spectroscopic ellipsometry and was found to depend on the deposition temperature. Optical absorption measurements show that the absorption from the f-f transitions depends strongly on the crystallinity of the material. The clear correlation between the degree of crystallinity, optical absorptions and refractive indices is discussed. PMID:23774891

  6. Local rhombohedral symmetry in Tb{sub 0.3}Dy{sub 0.7}Fe{sub 2} near the morphotropic phase boundary

    SciTech Connect

    Ma, Tianyu; Liu, Xiaolian; Pan, Xingwen; Li, Xiang; Jiang, Yinzhu; Yan, Mi; Li, Huiying; Fang, Minxia; Ren, Xiaobing

    2014-11-10

    The recently reported morphotropic phase boundary (MPB) in a number of giant magnetostrictive materials (GMMs) has drawn considerable interest to the local symmetry/structure near MPB region of these materials. In this letter, by in-situ X-ray diffraction and AC magnetic susceptibility measurements, we show that Tb{sub 0.3}Dy{sub 0.7}Fe{sub 2}, the typical composition of Terfenol-D GMMs, has coexistence of rhombohedral and tetragonal phases over a wide temperature range in the vicinity of MPB. High resolution transmission electron microscopy provides direct evidence for local rhombohedral symmetry of the ferromagnetic phase and reveals regular-shaped nanoscale domains below 10?nm. The nano-sized structural/magnetic domains are hierarchically inside a single micron-sized stripe-like domain with the same average magnetization direction. Such domain structures are consistent with the low magnetocrystalline anisotropy and easy magnetic/structural domain switching under magnetic field, thus generating large magnetostriction at low field.

  7. 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

  8. 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; Wang, Yuhua; Zhao, Lei; Zhang, Jia; Wang, Yanzhao; Tao, Ye

    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.

  9. 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.; Hwu, Shiou-Jyh

    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.

  10. 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

  11. 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 1325C to 1530C 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 750C, 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.

  12. Synthesis and structure determination of seven ternary bismuthides: crystal chemistry of the RELi3Bi2 family (RE = La-Nd, Sm, Gd, and Tb).

    PubMed

    Prakash, Jai; Schäfer, Marion C; Bobev, Svilen

    2015-10-01

    Zintl phases are renowned for their diverse crystal structures with rich structural chemistry and have recently exhibited some remarkable heat- and charge-transport properties. The ternary bismuthides RELi3Bi2 (RE = La-Nd, Sm, Gd, and Tb) (namely, lanthanum trilithium dibismuthide, LaLi3Bi2, cerium trilithium dibismuthide, CeLi3Bi2, praseodymium trilithium dibismuthide, PrLi3Bi2, neodymium trilithium dibismuthide, NdLi3Bi2, samarium trilithium dibismuthide, SmLi3Bi2, gadolinium trilithium dibismuthide, GdLi3Bi2, and terbium trilithium dibismuthide, TbLi3Bi2) were synthesized by high-temperature reactions of the elements in sealed Nb ampoules. Single-crystal X-ray diffraction analysis shows that all seven compounds are isostructural and crystallize in the LaLi3Sb2 type structure in the trigonal space group P-3m1 (Pearson symbol hP6). The unit-cell volumes decrease monotonically on moving from the La to the Tb compound, owing to the lanthanide contraction. The structure features a rare-earth metal atom and one Li atom in a nearly perfect octahedral coordination by six Bi atoms. The second crystallographically unique Li atom is surrounded by four Bi atoms in a slightly distorted tetrahedral geometry. The atomic arrangements are best described as layered structures consisting of two-dimensional layers of fused LiBi4 tetrahedra and LiBi6 octahedra, separated by rare-earth metal cations. As such, these compounds are expected to be valance-precise semiconductors, whose formulae can be represented as (RE(3+))(Li(1+))3(Bi(3-))2. PMID:26422218

  13. Effect of symmetry reduction on the electronic transitions in polytypic GdAl3(BO3)4:Eu:Tb crystals

    NASA Astrophysics Data System (ADS)

    Lengyel, K.; Beregi, E.; Földvári, I.; Corradi, G.; Kovács, L.; Solarz, P.; Ryba-Romanowski, W.

    2016-03-01

    The existence of a recently described monoclinic phase (C2/c, Z = 8) (Beregi et al., 2012) in addition to the well-known Huntite type rhombohedral (R32) polytypic modification of the GdAl3(BO3)4 (GAB) crystal at room temperature provides a unique possibility to investigate the incorporation of rare earth dopants into slightly modified crystal lattice by spectroscopic methods. In these characteristic GAB structures the dopant ions, e.g. Tb3+ or Eu3+, possess slightly different neighbor geometries and local symmetries. The Tb3+: 7F6 → 5D4 and Eu3+: 7F0,1,2 → 5D0,1,2 electronic transitions were successfully identified in the absorption spectra using polarization, concentration and temperature dependent measurements in both polytypic modifications. The positions of the investigated Tb lines are shifted by up to 10 cm-1 due to symmetry changes. In addition, some of the Eu lines show splittings of about 4-30 cm-1 as a consequence of the change of the local environment. From the room temperature absorption measurements some of the low energy crystal field levels of 7F and 5D states of the Eu3+ ions were successfully determined for both modifications.

  14. Dopant-mediated structural and magnetic properties of TbMnO3

    NASA Astrophysics Data System (ADS)

    Sharma, Vinit; McDannald, A.; Staruch, M.; Ramprasad, R.; Jain, M.

    2015-07-01

    Structural and magnetic properties of the doped terbium manganites (Tb,A)MnO3 (A = Gd, Dy, and Ho) have been investigated using first-principles calculations and further confirmed by subsequent experimental studies. Both computational and experimental studies suggest that compared to the parent material, namely, TbMnO3 (with a magnetic moment of 9.7 μ B for Tb3+) Dy- and Ho-ion substituted TbMnO3 results in an increase in the magnetic susceptibility at low fields ( ≤ 10.6 μ B for Dy3+ and Ho3+). The observed spiral-spin AFM order in TbMnO3 is stable with respect to the dopant substitutions, which modify the Mn-O-Mn bond angles and lead to stronger the ferromagnetic component of the magnetic moment. Given the fact that magnetic ordering in TbMnO3 causes the ferroelectricity, this is an important step in the field of the magnetically driven ferroelectricity in the class of magnetoelectric multiferroics, which traditionally have low magnetic moments due to the predominantly antiferromagnetic order. In addition, the present study reveals important insights on the phenomenological coupling mechanism in detail, which is essential in order to design new materials with enhanced magneto-electric effects at higher temperatures.

  15. Optimization of Pr3+, Tb3+, and Sm3+ co-doped (Y0.65Gd0.35)BO3:Eu0.05(3+) VUV phosphors through combinatorial approach.

    PubMed

    Chen, Lei; Fu, Yibing; Zhang, Guobin; Bao, Jun; Gao, Chen

    2008-01-01

    A combinatorial approach was used to systematically investigate the effect of trace Pr(3+), Tb(3+), or Sm(3+) on the VUV photoluminescence of Eu(3+) in the Pr(3+), Tb(3+), or Sm(3+) co-doped (Y(0.65)Gd(0.35))BO(3):E(3+)(0.05). We found that Pr(3+) and Tb(3+)increases the VUV photoluminescent efficiency, while Sm(3+) decreases the efficiency. The optimized composition was identified to be between 7 x 10(-6) and 3 x 10(-4), and the corresponding efficiency improvement is about 15%. Scale-up experiments confirmed the results in the combinatorial materials libraries. PMID:18336007

  16. Electronic structure of rare-earth chromium antimonides RECrSb3 (RE=La-Nd, Sm, Gd-Dy, Yb) by X-ray photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Crerar, Shane J.; Mar, Arthur; Grosvenor, Andrew P.

    2012-12-01

    The electronic structure of the ternary rare-earth chromium antimonides RECrSb3 (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 RE2O3 tends to support the presence of trivalent RE atoms in RECrSb3. However, the Yb 4d spectrum of YbCrSb3 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 RECrSb3. The experimental valence band spectrum of LaCrSb3 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 (“La3+Cr3+(Sb2-)3”). On progressing from LaCrSb3 to NdCrSb3, the 4f-band in the valence band spectra grows in intensity and shifts to higher BE. The valence band spectrum for YbCrSb3 also supports the presence of divalent ytterbium.

  17. Development of lead free magnetoelectric laminates of Na0.5Bi0.5TiO3-Tb0.3Dy0.7Fe1.95 for power generation

    NASA Astrophysics Data System (ADS)

    Prabahar, K.; Mirunalini, Josephine; Sowmya, N. Shara; Chelvane, J. Arout; Mahendiran, M.; Kamat, S. V.; Srinivas, A.

    2014-09-01

    Lead free magnetoelectric laminates has been prepared by sandwiching Sodium Bismuth Titanate (Na0.5Bi0.5TiO3) between two Tb0.3Dy0.7Fe1.95 (TDF) by epoxy bonding. The piezoelectric material Sodium Bismuth Titanate (Na0.5Bi0.5TiO3) has been prepared by conventional solid state double sintering method and the magnetostrictive material, Tb0.3Dy0.7Fe1.95 (TDF) by vacuum induction melting process. NBT showed a saturated ferroelectric hysteresis behavior with the values of Ps=22.24 ?C/cm2, Ec=41 kV/cm and Pr=27 ?C/cm2. The piezoelectric charge coefficient (d33) measured for NBT was 102 pC/N. Magnetization versus magnetic field measurements were performed in longitudinal (L) and transverse (T) modes of TDF specimen that showed ferromagnetic hysteresis behavior. The magnetostriction of 950 ppm at 4 kOe and static strain coefficient of 0.3710-6 kOe-1 at 1 kOe magnetic field were recorded for Tb0.3Dy0.7Fe1.95. The magnetoelectric output was measured in L and T modes for the different NBT thickness of 1.0, 1.5 and 2 mm with TDF thickness of 1.5 mm. The high magnetoelectric coefficient (?) was found to be 0.08 mV/cm Oe (L mode) and 0.13 mV/cm Oe (T mode) for the NBT/TDF laminates with 1.0 mm thick NBT.

  18. The crystal structure and luminescence of Ce3+, Tb3+ and Eu3+ in KBaLn3+(BO3)2 [Ln3+ = Sc, Y, Lu, Gd

    NASA Astrophysics Data System (ADS)

    Camardello, S. J.; Her, J. H.; Toscano, P. J.; Srivastava, A. M.

    2015-11-01

    The structure of KBaLn3+(BO3)2 [Ln3+ = Sc, Lu, Gd] was solved by Rietveld refinement of the powder X-ray diffraction data. The materials crystallize with the mineral Buetschliite [K2Ca(CO3)2] structure. The lattice parameters of KBaLn3+(BO3)2 [Ln3+ = Sc, Lu, Gd] increased with increasing ionic radius of the Ln3+ cation. In this structure, the Ln3+ cations are octahedrally coordinated. The phase formation region is dependent on the ionic radii of the Ln3+ cation. The optical properties of Ce3+, Tb3+ and Eu3+ and their dependence on the host lattice composition are investigated and discussed. It is noteworthy that the optical properties of these ions are independent of the Ln3+ cation in KBaLn3+(BO3)2. It is concluded that in this family of materials, the crystalline field strength and the covalence at the rare earth site is independent of the host lattice composition.

  19. Microscopic Evidence of Spin State Order and Spin State Phase Separation in Layered Cobaltites RBaCo2O5.5 with R=Y, Tb, Dy, and Ho

    NASA Astrophysics Data System (ADS)

    Luetkens, H.; Stingaciu, M.; Pashkevich, Yu. G.; Conder, K.; Pomjakushina, E.; Gusev, A. A.; Lamonova, K. V.; Lemmens, P.; Klauss, H.-H.

    2008-07-01

    We report muon-spin relaxation measurements on the magnetic structures of RBaCo2O5.5 with R=Y, Tb, Dy, and Ho. Three different phases, one ferrimagnetic and two antiferromagnetic, are identified below 300 K. They consist of different ordered spin state arrangements of high-, intermediate-, and low-spin Co3+ of CoO6 octahedra. Phase separation into well separated regions with different spin state order is observed in the antiferromagnetic phases. The unusual strongly anisotropic magnetoresistance and its onset at the FM-AFM phase boundary is explained.

  20. Co substitution effect on magnetic properties of magnetostrictive compounds Tb 0.36Dy 0.64(Fe 1-xCo x) 2 (0⩽ x⩽0.30)

    NASA Astrophysics Data System (ADS)

    Ma, Tianyu; Yan, Mi; Chen, Xianyan; Jiang, Chengbao; Xu, Huibin

    2008-10-01

    The substitution effect of Co for Fe on magnetic properties of giant magnetostrictive compounds Tb 0.36Dy 0.64(Fe 1-xCo x) 2 (0⩽ x⩽0.30) was examined by 57Fe Mössbauer measurements. It was found that the Co substitution did not change the easy magnetization direction (EMD). The average hyperfine fields and the deduced Fe moment increased with increasing Co content. The composition dependences of the magnetic transition temperatures, magnetization and magnetostrictions were consistent with the variation of hyperfine parameters, which can be ascribed to the 3d electrons transfer between Fe and Co atoms.

  1. On the nature of low-lying collective 1+ states in the heavy deformed nuclei 154Sm, 156Gd and 164Dy and in the f7/2 shell nucleus 46Ti

    NASA Astrophysics Data System (ADS)

    Djalali, C.; Marty, N.; Morlet, M.; Willis, A.; Jourdain, J. C.; Bohle, D.; Hartmann, U.; Küchler, G.; Richter, A.; Caskey, G.; Crawley, G. M.; Galonsky, A.

    1985-12-01

    High resolution inelastic proton scattering at 201 MeV on 154Sm, 156Gd and 164Dy is used to clarify the nature of low-lying magnetic dipole states previously observed in inelastic electron scattering. An upper limit on the spin contribution to these collective magnetic dipole excitations is presented. The roles of spin and convection currents are also studied by inelastic proton and electron scattering to the low-lying 1+ state at 4.319 MeV in the f7/2-shell nucleus 46Ti. A substantial orbital contribution is observed in all cases.

  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.; Lausi, A.; Bettinelli, M.

    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. Infrared study of lattice dynamics and spin-phonon and electron-phonon interactions in multiferroic TbF e3(BO3) 4 and GdF e3(BO3) 4

    NASA Astrophysics Data System (ADS)

    Klimin, S. A.; Kuzmenko, A. B.; Kashchenko, M. A.; Popova, M. N.

    2016-02-01

    We present a comparative far-infrared reflection spectroscopy study of phonons, phase transitions, spin-phonon, and electron-phonon interactions in isostructural multiferroic iron borates of gadolinium and terbium. The behavior of phonon modes registered in a wide temperature range is consistent with a weak first-order structural phase transition [Ts=143 for GdF e3(BO3) 4 and 200 K for TbF e3(BO3) 4 ] from a high-symmetry high-temperature R 32 structure into a low-symmetry low-temperature P 3121 one. The temperature dependences of frequencies, oscillator strengths, and damping constants of some low-frequency modes reveal an appreciable lattice anharmonicity. Peculiarities in the phonon mode behavior in both compounds at the temperature of an antiferromagnetic ordering [TN=32 K for GdF e3(BO3) 4 and 40 K for TbF e3(BO3) 4 ] evidence the spin-phonon interaction. In the energy range of phonons, GdF e3(BO3) 4 has no electronic levels, but TbF e3(BO3) 4 possesses several. We observe an onset of new bands in the excitation spectrum of TbF e3(BO3) 4 due to a resonance interaction between a lattice phonon and 4 f electronic crystal-field (CF) excitations of T b3 + . This interaction causes delocalization of the CF excitations, their Davydov splitting, and formation of coupled electron-phonon modes.

  4. Synthesis, structures, and magnetic properties of a family of 3d-4f [Na2Fe6Ln2] complexes (Ln = Y, Gd and Dy): effect of ligands on the connection of inorganic subunits.

    PubMed

    Zhou, Qi; Yang, Fen; Liu, Dan; Peng, Yu; Li, Guanghua; Shi, Zhan; Feng, Shouhua

    2013-01-28

    A family of 3d-4f heterometallic compounds [Na(2)Fe(III)(6)Dy(III)(2)(N(3))(4)(HL)(4)(CH(3)O)(4)(PhCO(2))(6)] (1, H(4)L = 2-{[(2-hydroxy-3-methoxyphenyl)methylene]amino}-2-(hydroxymethyl)-1,3-propanediol), [Na(2)Fe(III)(6)Dy(III)(2)(N(3))(4)(L')(4)(CH(3)O)(4)(PhCO(2))(6)(H(2)O)] (2, H(3)L' = (E)-2-ethyl-2-(2-hydroxy-3-methoxybenzylideneamino)propane-1,3-diol), [Na(2)Fe(III)(6)Dy(III)(2)(N(3))(4)(L')(4)(CH(3)O)(4)(Bu(t)CO(2))(6)] (3) [Na(2)Fe(III)(6)Y(III)(2)(N(3))(4)(L')(4)(CH(3)O)(4)(PhCO(2))(6)(H(2)O)] (4), and [Na(2)Fe(III)(6)Gd(III)(2)(N(3))(4)(L')(4)(CH(3)O)(4)(PhCO(2))(6)(CH(3)OH)(2)] (5) have been prepared using Schiff-base ligands, trinuclear iron precursor complexes, azides and lanthanide nitrates as reactants. In compounds 1 and 2, the structure of the [Na(2)Fe(III)(6)Dy(III)(2)] cluster forms a couple of cis,trans-isomers with substitution of methyl for a free hydroxyl group which belongs to the Schiff-base ligand. When the pivalates are employed instead of bulkier benzoates, the trans-[Na(2)Fe(III)(6)Dy(III)(2)] clusters act as network nodes in the formation of rhombic grid-like layered structures in compound 2. Compounds 2, 4 and 5 have similar metallic cores, only with different crystal solvent molecules. The magnetic measurements on all the compounds indicate dominant antiferromagnetic interactions between the metal centers. PMID:23114511

  5. Internal And External Factors in the Structural Organization in Cocrystals of the Mixed-Metal Endohedrals (GdSc2N@I(H)-C(80), Gd(2)ScN@I(H)-C(80), And TbSc(2)N@I(H)C(80) ) And Nickel(II) Octaethylporphyrin

    SciTech Connect

    Stevenson, S.; Chancellor, C.J.; Lee, H.M.; Olmstead, M.M.; Balch, A.L.

    2009-05-26

    Structural characterizations of three new mixed-metal endohedrals, GdSc{sub 2}N@I{sub h}-C{sub 80}, Gd{sub 2}ScN@I{sub h}-C{sub 80}, and TbSc{sub 2}@I{sub h}-C{sub 80}, have been obtained by single-crystal X-ray diffraction on GdSc{sub 2}N@I{sub h}-C{sub 80}{center_dot}Ni{sup II}(OEP){center_dot}2C{sub 6}H{sub 6}, Gd{sub 2}ScN@I{sub h}-C{sub 80}{center_dot}Ni{sup II}(OEP){center_dot}2C{sub 6}H{sub 6}, and TbSc{sub 2}N@I{sub h}-C{sub 80}{center_dot}Ni{sup II}(OEP){center_dot}2C{sub 6}H{sub 6}. All three have I{sub h}-C{sub 80} cages and planar MM'{sub 2}N units. The central nitride ion is positioned further from the larger Gd{sup 3+} or Tb{sup 3+} ions and closer to the smaller Sc{sup 3+} ions. The MM'{sub 2}N units show a remarkable degree of orientational order in these and related compounds in which the endohedral fullerene is cocrystallized with a metalloporphyrin. The MM'{sub 2}N units are oriented perpendicularly to the porphyrin plane and aligned along one of the N-Ni-N axes of the porphyrin. The smaller Sc{sup 3+} ions show a marked preference to lie near the porphyrin plane. The larger Gd{sup 3+} or Tb{sup 3+} ions assume positions further from the plane of the porphyrin. The roles of dipole forces and electrostatic forces in ordering these cocrystals of endohedral fullerenes and metalloporphyrins are considered.

  6. Up/down conversion luminescence and charge compensation investigation of Ca0.5Y1-x(WO4)2:xLn3+ (Ln = Pr, Sm, Eu, Tb, Dy, Yb/Er) phosphors

    NASA Astrophysics Data System (ADS)

    Mahalingam, Venkatakrishnan; Thirumalai, Jagannathan; Krishnan, Rajagopalan; Mantha, Srinivas

    2016-01-01

    Microstructures of Ca0.5Y(1-x)(WO4)2:xLn3+ (Ln = Pr, Sm, Eu, Tb, Dy, Yb/Er) phosphors were prepared via the solid-state reaction method. X-ray diffraction, scanning electron microscopy and photoluminescence were used to characterize the prepared phosphor samples. The results reveal that the phosphor samples have single phase scheelite structures with tetragonal symmetry of I41/a. The down/up conversion photoluminescence of the Ca0.5Y(1-x)(WO4)2:xLn3+ (Ln = Pr, Sm, Eu, Tb, Dy, Yb/Er) phosphors properties reveal characteristic visible emissions. The energy transfer process, fluorescence lifetime and color coordinates are discussed in detail. Furthermore, the phosphor Ca0.5Y(1-x)(WO4)2:xPr3+ co-doped with alkali chlorides shows the enhancement of luminescence, which was found in the sodium chloride co-doped powder phosphor. The photometric characteristics indicate the suitability of the inorganic powder phosphors for solid-state lighting and display applications.

  7. 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.; Mar, Arthur; Grosvenor, Andrew P.

    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.

  8. Hydrothermal synthesis, structure, and optical properties of two nanosized Ln26 @CO3 (Ln=Dy and Tb) cluster-based lanthanide-transition-metal-organic frameworks (Ln MOFs).

    PubMed

    Zhang, Yu; Huang, Lian; Miao, Hao; Wan, Hong Xiang; Mei, Hua; Liu, Ying; Xu, Yan

    2015-02-16

    Two Ln26 @CO3 (Ln=Dy and Tb) cluster-based lanthanide-transition-metal-organic frameworks (Ln MOFs) formulated as [Dy26 Cu3 (Nic)24 (CH3 COO)8 (CO3 )11 (OH)26 (H2 O)14 ]Cl ⋅3 H2 O (1; HNic=nicotinic acid) and [Tb26 NaAg3 (Nic)27 (CH3 COO)6 (CO3 )11 (OH)26 Cl(H2 O)15 ]⋅7.5 H2 O (2) have been successfully synthesized by hydrothermal methods and characterized by IR, thermogravimetric analysis (TGA), elemental analysis, and single X-ray diffraction. Compound 1 crystallizes in the monoclinic space group Cc with a=35.775(12) Å, b=33.346(11) Å, c=24.424(8) Å, β=93.993(5)°, V=29065(16) Å(3) , whereas 2 crystallizes in the triclinic space group P$\\bar 1$ with a=20.4929(19) Å, b=24.671(2) Å, c=29.727(3) Å, α=81.9990(10)°, β=88.0830(10)°, γ=89.9940(10)°, V=14875(2) Å(3) . Structural analysis indicates the framework of 1 is a 3D perovskite-like structure constructed out of CO3 @Dy26 building units and Cu(+) centers by means of nicotinic acid ligand bridging. In 2, however, nanosized CO3 @Tb26 units and [Ag3 Cl](2+) centers are connected by Nic(-) bridges to give rise to a 2D structure. It is worth mentioning that this kind of 4d-4f cluster-based MOF is quite rare as most of the reported analogous compounds are 3d-4f ones. Additionally, the solid-state emission spectra of pure compound 2 at room temperature suggest an efficient energy transfer from the ligand Nic(-) to Tb(3+) ions, which we called the "antenna effect". Compound 2 shows a good two-photon absorption (TPA) with a TPA coefficient of 0.06947 cm GM(-1) (1 GM=10(-50)  cm(4)  s photon(-1) ), which indicates that compound 2 might be a good choice for third-order nonlinear optical materials. PMID:25487542

  9. Strong magnetic coupling in the hexagonal R5Pb3 compounds (R=Gd-Tm)

    NASA Astrophysics Data System (ADS)

    Marcinkova, Andrea; de la Cruz, Clarina; Yip, Joshua; Zhao, Liang L.; Wang, Jiakui K.; Svanidze, E.; Morosan, E.

    2015-06-01

    We have synthesized the R5Pb3 (R=Gd-Tm) compounds in polycrystalline form and performed neutron scattering and magnetization measurements. For all R5Pb3 reported here the Weiss temperatures θW are several times smaller than the ordering temperatures TORD, while the latter are remarkably high (TORD up to 275 K for R=Gd) compared to other known R-M binaries (M=Si, Ge, Sn and Sb). The magnetic order changes from ferromagnetic (FM) in R=Gd, Tb to antiferromagnetic (AFM) in R=Dy-Tm. Below TORD, the magnetization measurements together with neutron powder diffraction show complex magnetic behaviors and reveal the existence of up to three additional phase transitions, believed to be a result of large anisotropic exchange and/or crystal electric field effects, induced high anisotropy. The R5Pb3 magnetic unit cells for R=Tb-Tm can be described with incommensurate magnetic wave vectors with spin modulation either along the c axis in R=Tb, Er and Tm, or within the ab plane in R=Dy and Ho.

  10. Nine members of a family of nine-membered cyclic coordination clusters; Fe6Ln3 wheels (Ln = Gd to Lu and Y).

    PubMed

    Kühne, Irina A; Mereacre, Valeriu; Anson, Christopher E; Powell, Annie K

    2016-01-18

    We report a family of isostructural nonanuclear Fe(III)-Ln(III) cyclic coordination clusters [Fe(III)(6)Ln(III)(3)(μ-OMe)9(vanox)6(benz)6]. (Ln = Tb (1), Dy (2), Ho (3), Er (4), Tm (5), Yb (6), Lu (7), Y (8) and Gd (9)), containing an odd number of metal ions. The planar cyclic coordination cluster cores are built up from three [Fe2Ln] subunits. PMID:26592179

  11. Hydrothermal synthesis and tunable luminescence of CaSiO{sub 3}:RE{sup 3+}(RE{sup 3+} = Eu{sup 3+}, Sm{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) nanocrystals

    SciTech Connect

    Fu, Linlin; Yang, Xingxing; Fu, Zuoling; Wu, Zhijian; Jeong, Jung Hyun

    2015-05-15

    Highlights: • Near-spherical CaSiO{sub 3} nanocrystals were synthesized via a hydrothermal method. • The effect of calcination temperature on crystalline phase formation was discussed. • Optical properties of trivalent ions doped CaSiO{sub 3} nanocrystals were investigated. • Tunable luminescence of CaSiO{sub 3}:Tb{sup 3+}, Eu{sup 3+} can be achieved by a simple method. - Abstract: CaSiO{sub 3}:RE{sup 3+} (RE{sup 3+} = Eu{sup 3+}, Sm{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) nanocrystals were prepared by facile hydrothermal method with further calcinations. The crystal structure and the effects of annealing temperature on phase transition have been characterized by X-ray diffraction (XRD). The photoluminescence (PL) and PL excitation (PLE) spectra were used to characterize the optical properties of all samples. The effect of Eu{sup 3+} and Sm{sup 3+} doping concentrations on the luminescent intensity were also investigated in details, respectively. Moreover, the luminescence colors of the Tb{sup 3+} and Eu{sup 3+} co-doped CaSiO{sub 3} samples can be tuned by simply adjusting the relative doping concentrations of the rare earth ions under a single wavelength excitation, which might find potential applications in the fields of light display systems and optoelectronic devices.

  12. Family of dumbbell Ni4Ln2 (Ln = Pr, Sm, Eu, Gd, Tb, Ho, Er) complexes: syntheses, structures, luminescent and magnetic properties.

    PubMed

    Liu, Baolin; Liu, Qingxia; Xiao, Hongping; Zhang, Wu; Tao, Ruojie

    2013-04-14

    The synthesis and characterization of a family of heterometallic Ni4Ln2 complexes (Ln = Pr(1), Sm(2), Eu(3), Gd(4), Tb(5), Ho(6) and Er(7)) of the formula [Ni2LnL1L2(OH)(H2O)]2 are reported, where H4L1 is 3,3′-(1E,1′E)-(2,2′-(2-aminoethylazanediyl)bis(ethane-2,1-diyl)bis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)bis(2-hydroxybenzoic acid) and H2L2 is 3-formyl-2-hydroxybenzoic acid. The molecular structures of 1–7 were determined by single-crystal X-ray diffraction and reveal that they are isostructural. In all of these compounds, the six metal ions are held together to form a novel Ni4Ln2O10 core and exhibit a relatively rare dumbbell-type structure. In these compounds, the Ni ions are in slightly distorted square-pyramidal or octahedral environments. An all-oxygen coordination environment (8O) is present around the central lanthanide ion, which is present in a distorted square antiprismatic geometry. The Ln–Ln and Ln–Oavg bond distances in 1–7 show a gradual reduction proceeding from 1 to 7, in accordance with the lanthanide contraction. The luminescent properties of all the compounds have been studied. The magnetic susceptibility analysis demonstrate antiferromagnetic interactions within complex 4. PMID:23396382

  13. Heterobinuclear Zn-Ln (Ln = La, Nd, Eu, Gd, Tb, Er and Yb) complexes based on asymmetric Schiff-base ligand: synthesis, characterization and photophysical properties.

    PubMed

    Zhao, Shunsheng; Liu, Xiangrong; Lü, Xingqiang; Wong, Wai-Kwok

    2013-01-01

    With a novel asymmetric Schiff-base zinc complex ZnL (H2 L = N-(3-methoxysalicylidene)-N'-(5-bromo-3-methoxysalicylidene)phenylene-1,2-diamine), obtained from phenylene-1,2-diamine, 3-methoxysalicylaldehyde and 5-bromo-3-methoxysalicylaldehyde, as the precursor, a series of heterobinuclear Zn-Ln complexes [ZnLnL(NO3 )3 (CH3 CN)] (Ln = La, 1; Ln = Nd, 2; Ln = Eu, 3; Ln = Gd, 4; Ln = Tb, 5; Ln = Er, 6; Ln = Yb, 7) were synthesized by the further reaction with Ln(NO3 )3 ·6H2 O, and characterized by Fourier transform-infrared, fast atom bombardment mass spectroscopy and elemental analysis. Photophysical studies of these complexes show that the strong and characteristic near-infrared luminescence of Nd(3+) , Yb(3+) and Er(3+) with emissive lifetimes in the microsecond range has been sensitized from the excited state of the asymmetric Schiff-base ligand due to effective intramolecular energy transfer; the other complexes do not show characteristic emission due to the energy gap between the chromophore and lanthanide ions. PMID:23001932

  14. 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.

  15. 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 . E-mail: cesbin@mail.sysu.edu.cn; Su Qiang; Tao Ye; Xu Jianhua; Huang Yan

    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.

  16. High-Temperature Salt Flux Crystal Growth of New Lanthanide Molybdenum Oxides, Ln5Mo2O12 Ln = Eu, Tb, Dy, Ho, and Er: Magnetic Coupling within Mixed Valent Mo(IV/V) Rutile-Like Chains.

    PubMed

    Cortese, Anthony J; Abeysinghe, Dileka; Wilkins, Branford; Smith, Mark D; Morrison, Gregory; Zur Loye, Hans-Conrad

    2015-12-21

    Five new lanthanide molybdenum oxides containing mixed valent Mo(IV/V) rutile-like chains, Ln5Mo2O12 Ln = Eu, Tb, Dy, Ho, and Er, were prepared utilizing a high-temperature molten salt flux synthesis involving an in situ reduction utilizing metallic reducing agents. All five compounds were structurally characterized by single-crystal and powder X-ray diffraction methods and were found to crystallize in the monoclinic space group C2/m. The molybdates all contain rare infinite chains consisting of MoO2O4/2 edge-sharing octahedra. The chains exhibit alternating long and short separations between octahedra caused by the presence of Mo-Mo bonds to form Mo2O10 units containing one unpaired electron. The temperature dependence of the magnetic susceptibility of these compounds was measured, and antiferromagnetic ordering was observed in all cases. PMID:26629588

  17. 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; Grytsiv, Andriy; Rogl, Peter; Seropegin, Yurii; Giester, Gerald

    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.

  18. Magnetic ordering in the pyrochlore Ho2CrSbO7 determined from neutron diffraction, and the magnetic properties of other RE2CrSbO7 phases (RE=Y, Tb, Dy, Er)

    NASA Astrophysics Data System (ADS)

    Whitaker, Mariana J.; Greaves, Colin

    2014-07-01

    The magnetic structure of the pyrochlore Ho2CrSbO7, which orders magnetically below 13 K, has been studied using neutron powder diffraction. Ho2CrSbO7 is found to form an “ordered spin-ice structure” where the magnetic moments are constrained along the 111 axes, but with a ferromagnetic moment in one direction. The Cr3+ ions order ferromagnetically and this is thought to lift the degeneracy of the x, y and z directions in the cubic structure causing the ferromagnetic component from the Ho3+ ions to align. The pyrochlores RE2CrSbO7 where RE=Y, Tb, Dy and Er have also been prepared and studied using SQUID magnetometry.

  19. 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(μ4-O)2(μ3-OH)2(mdea)7(μ-benzoate)4(N3)6]·4MeCN·H2O, where Ln = Gd(III) (1) or Tb(III) (2), and [Er3Fe7(μ4-O)2(μ3-OH)2(mdea)7(μ-benzoate)4(N3)5(MeOH)]Cl·7.5H2O·11.5MeOH (3). The isostructural compounds 1-3 all crystallize isotypically in the triclinic space group P1̅ 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 (χ″) 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

  20. 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; Yang, Hyun Kyoung; Moon, Byung Kee; Choi, Byung Chun; Jeong, Jung Hyun; Kim, Kwang Ho

    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.

  1. The molecular structure of TbI 3, DyI 3, HoI 3 and ErI 3 as determined by synchronous gas-phase electron diffraction and mass spectrometric experiment assisted by quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Shlykov, Sergey A.; Giricheva, Nina I.; Lapykina, Elena A.; Girichev, Georgiy V.; Oberhammer, Heinz

    2010-08-01

    A first gas electron diffraction study of TbI 3, DyI 3, HoI 3 and ErI 3 has been carried out in combination with mass spectrometric vapour monitoring at 1117(10), 1117(10), 1132(10) and 1102(10) K, respectively. Up to 4 mol.% of dimeric species was observed in addition to the dominating monomeric molecules. The change of the thermal-averaged rg-configuration parameters of the molecules in the series TbI 3 → ErI 3 reflect the lanthanide contraction. A low value of the shrinkage δ(I…I) even at such a high temperatures may be considered due to vibration effects in molecule whose equilibrium geometric nuclear structure is planar and which correspond to configurationally-averaged 4f n electronic state. B3LYP and МР2 calculations performed in this work with large core potential for lanthanide atoms also resulted in equilibrium geometry of D 3h symmetry. According to the both quantum chemical methods applied the potential function the non-planar vibration is essentially anharmonic, which is therefore to be taken into account to correctly describe nuclear dynamics in molecules such as LnI 3. Different models applied in this study predict the equilibrium distance re(Ln-I) to be shorter than the thermal-averaged rg(Ln-I) distance by 0.002-0.018(1) Å.

  2. Magnetic properties of RE5Ir2X (RE = Y, Gd-Ho, X = Sn, Sb, Pb, Bi) and magnetocaloric characterization of Gd5Ir2X

    NASA Astrophysics Data System (ADS)

    Schäfer, Konrad; Schwickert, Christian; Niehaus, Oliver; Winter, Florian; Pöttgen, Rainer

    2014-09-01

    Systematic phase analytical studies of the systems RE-Ir-X (X = Sn, Pb, Sb, Bi) led to 15 new stannides, plumbides, antimonides and bismuthides with the composition RE5Ir2X. The compounds have been synthesized and characterized by X-ray powder diffraction. The structures of Gd5Ir2Sb and Dy5Ir2Bi have been refined from single crystal X-ray diffractometer data: Mo5SiB2 type, I4/mcm, a = 775.2(2), c = 1361.3(5) pm, wR2 = 0.0933, 404 F2 values, 16 variables for Gd5Ir2Sb and a = 767.5(1), c = 1368.9(3) pm, wR2 = 0.0694, 571 F2 values, 16 variables for Dy5Ir2Bi. Magnetic measurements of Gd5Ir2X (X = Sn, Pb, Sb, Bi), Tb5Ir2X (X = Sn, Pb, Sb, Bi), Dy5Ir2Pb, Dy5Ir2Bi and Ho5Ir2Pb indicate ferromagnetic transitions at TC = 154.3, 159.3, 124.4, 119.3, 99.2, 98.2, 65.5, 68.6, 45.1, 35.6 and 23.5 K, respectively. Gd5Ir2Bi and Gd5Ir2Sb show an additional antiferromagnetic transition at TN = 118.5 and 91.0 K. The magnetocaloric effect of Gd5Ir2X (X = Sn, Pb, Sb, Bi) in terms of the isothermal entropy change ΔSm is -7.3(3), -6.5(3), -8.7(3) and -9.0(3) J kg-1 K-1 at temperatures of 153, 157, 120 and 126 K for a 5 T field change. 119Sn Mössbauer spectra of Gd5Ir2Sn at 78 K show a huge transferred hyperfine field of 21.9(1) T and an isomer shift of 1.94(1) mm s-1, typical for stannides. 121Sb Mössbauer spectra of Gd5Ir2Sb at 78 K show a transferred hyperfine field of 14.2(3) T and an isomer shift of -7.45(8) mm s-1 reflecting the antimonide character.

  3. A new family of [Cu(II)Ln(III)M(V)] heterotrimetallic complexes (Ln = La, Gd, Tb; M = Mo, W): model systems to probe exchange interactions and single-molecule magnet properties.

    PubMed

    Visinescu, Diana; Alexandru, Maria-Gabriela; Madalan, Augustin M; Jeon, Ie-Rang; Mathonière, Corine; Clérac, Rodolphe; Andruh, Marius

    2016-05-01

    Four isostructural trinuclear 3d-4f-4(5)d heterotrimetallic complexes, with the general formula [L(2)CuLn(H2O)5(μ-NC)M(CN)7], were obtained from the association of binuclear 3d-4f complexes and {M(V)(CN)8}(3-) metalloligands (M = Mo, Ln = La ; M = W, Ln = La ; M = Mo, Ln = Gd ; M = Mo; Ln = Tb , where H2L(2) = 1,2-ethanediylbis(2-iminomethylene-6-methoxy-phenol)). The metalloligand coordinates through a single-cyanido group at the apical position of the copper(ii) ion belonging to the {Cu(II)Ln(III)} binuclear complex. The analysis of the magnetic data for the La(iii) derivatives (compounds and ), in the 1.85-300 K temperature range, shows a weak ferromagnetic exchange interaction between Cu(II) and Mo(V)/W(V) ions across the cyanido bridge (JCuM/kB = 3.6(6) K; g = 2.23(5) for and JCuM/kB = 3.8(6) K, g = 2.21(5) for , with H = -2JCuMSCu·SM). These results were used to simulate the magnetic properties of compound , using the isotropic spin Hamiltonian H = -2JCuMoSCu·SMo - 2JCuGdSCu·SGd. The resulting magnetic interaction between Cu(II) and Gd(III) ions via the phenoxo-bridge was found to be weakly ferromagnetic (JCuGd/kB = +4.5(2) K with JCuMo/kB = +3.6(2) K, gGd = gCu = 2.00 and gMo = 1.98). The dc magnetic properties for compound also show a predominant ferromagnetic interaction, while the ac magnetic measurements indicate the presence of the slow relaxation of the magnetization below 3.5 K. PMID:27052800

  4. Trends in Syntheses, Structures, and Properties for Three Series of Ammine Rare-Earth Metal Borohydrides, M(BH4)3·nNH3 (M = Y, Gd, and Dy).

    PubMed

    Jepsen, Lars H; Ley, Morten B; Černý, Radovan; Lee, Young-Su; Cho, Young Whan; Ravnsbæk, Dorthe; Besenbacher, Flemming; Skibsted, Jørgen; Jensen, Torben R

    2015-08-01

    Fourteen solvent- and halide-free ammine rare-earth metal borohydrides M(BH4)3·nNH3, M = Y, Gd, Dy, n = 7, 6, 5, 4, 2, and 1, have been synthesized by a new approach, and their structures as well as chemical and physical properties are characterized. Extensive series of coordination complexes with systematic variation in the number of ligands are presented, as prepared by combined mechanochemistry, solvent-based methods, solid-gas reactions, and thermal treatment. This new synthesis approach may have a significant impact within inorganic coordination chemistry. Halide-free metal borohydrides have been synthesized by solvent-based metathesis reactions of LiBH4 and MCl3 (3:1), followed by reactions of M(BH4)3 with an excess of NH3 gas, yielding M(BH4)3·7NH3 (M = Y, Gd, and Dy). Crystal structure models for M(BH4)3·nNH3 are derived from a combination of powder X-ray diffraction (PXD), (11)B magic-angle spinning NMR, and density functional theory (DFT) calculations. The structures vary from two-dimensional layers (n = 1), one-dimensional chains (n = 2), molecular compounds (n = 4 and 5), to contain complex ions (n = 6 and 7). NH3 coordinates to the metal in all compounds, while BH4(-) has a flexible coordination, i.e., either as a terminal or bridging ligand or as a counterion. M(BH4)3·7NH3 releases ammonia stepwise by thermal treatment producing M(BH4)3·nNH3 (6, 5, and 4), whereas hydrogen is released for n ≤ 4. Detailed analysis of the dihydrogen bonds reveals new insight about the hydrogen elimination mechanism, which contradicts current hypotheses. Overall, the present work provides new general knowledge toward rational materials design and preparation along with limitations of PXD and DFT for analysis of structures with a significant degree of dynamics in the structures. PMID:26196159

  5. Pentanuclear 3d-4f Heterometal Complexes of M(II)3Ln(III)2 (M = Ni, Cu, Zn and Ln = Nd, Gd, Tb) Combinations: Syntheses, Structures, Magnetism, and Photoluminescence Properties.

    PubMed

    Maity, Manoranjan; Majee, Mithun Chandra; Kundu, Sanchita; Samanta, Swarna Kamal; Saudo, E Carolina; Ghosh, Sanjib; Chaudhury, Muktimoy

    2015-10-19

    A new family of pentanuclear 3d-4f heterometal complexes of general composition [Ln(III)2(M(II)L)3(?3-O)3H](ClO4)xH2O (1-5) [Ln = Nd, M = Zn, 1; Nd, Ni, 2; Nd, Cu, 3; Gd, Cu, 4; Tb, Cu, 5] have been synthesized in moderate yields (50-60%) following a self-assembly reaction involving the hexadentate phenol-based ligand, viz., N,N-bis(2-hydroxy-3-methoxy-5-methylbenzyl)-N('),N(')-diethylethylenediamine (H2L). Single-crystal X-ray diffraction analyses have been used to characterize these complexes. The compounds are all isostructural, having a 3-fold axis of symmetry that passes through the 4f metal centers. The [M(II)L] units in these complexes are acting as bis-bidentate metalloligands and, together with ?3-oxido bridging ligands, complete the slightly distorted monocapped square antiprismatic nine-coordination environment around the 4f metal centers. The cationic complexes also contain a H(+) ion that occupies the central position at the 3-fold axis. Magnetic properties of the copper(II) complexes (3-5) show a changeover from antiferromagnetic in 3 to ferromagnetic 3d-4f interactions in 4 and 5. For the isotropic Cu(II)-Gd(III) compound 4, the simulation of magnetic data provides very weak Cu-Gd (J1 = 0.57 cm(-1)) and Gd-Gd exchange constants (J2 = 0.14 cm(-1)). Compound 4 is the only member of this triad, showing a tail of an out-of-phase signal in the ac susceptibility measurement. A large-spin ground state (S = 17/2) and a negative value of D (-0.12 cm(-1)) result in a very small barrier (8 cm(-1)) for this compound. Among the three Nd(III)2M(II)3 (M = Zn(II), Ni(II), and Cu(II)) complexes, only the Zn(II) analogue (1) displays an NIR luminescence due to the (4)F(3/2) ? (4)I(11/2) transition in Nd(III) when excited at 290 nm. The rest of the compounds do not show such Nd(III)/Tb(III)-based emission. The paramagnetic Cu(II) and Ni(II) ions quench the fluorescence in 2-5 and thereby lower the population of the triplet state. PMID:26407121

  6. Fully opposite spin polarization of electron and hole bands in DyN and related band structures of GdN and HoN

    NASA Astrophysics Data System (ADS)

    Cheiwchanchamnangij, Tawinan; Lambrecht, Walter R. L.

    2015-07-01

    Using quasiparticle self-consistent G W calculations, we show that DyN has an unusual nearly zero indirect gap semimetallic band structure in which the states near the valence band maximum are fully minority spin polarized at Γ while the states near the conduction band minimum (at X ) have fully majority spin character. This arises due to a strong hybridization of one of the minority spin f states of dysprosium with the N-2 p bands. The reason why only one of the f bands hybridizes is explained using symmetry arguments. We show that in HoN, this hybridization is already strongly reduced because of the deeper Ho-4 f minority spin states.

  7. A family of 12-azametallacrown-4 structural motif with heterometallic Mn(III) -Ln-Mn(III) -Ln (Ln=Dy, Er, Yb, Tb, Y) alternate arrangement and single-molecule magnet behavior.

    PubMed

    Yang, Hua; Cao, Fan; Li, Dacheng; Zeng, Suyuan; Song, You; Dou, Jianmin

    2015-10-01

    Mixed 3d-4f 12-azametallacrown-4 complexes, [Mn2 Ln2 (OH)2 (hppt)4 (OAc)2 (DMF)2 ]⋅2 DMF⋅H2 O [Ln=Dy (1), Er (2), Yb (3), Tb (4) and Y (5), H2 hppt=3-(2-hydroxyphenyl)-5-(pyrazin-2-yl)-1,2,4-triazole)], were synthesized by reactions of H2 hppt with Mn(OAc)2 ⋅4 H2 O and Ln(NO3 )3 ⋅6 H2 O. This is the first 3d-4f azametallacrown family to incorporate Ln ions into the ring sets. These isostructural complexes exhibit alternating arrangements of two Mn and two Ln ions in the rings with each pair of metal centers bound by an NN group and μ2 -O bridging. Magnetic measurements revealed dominant antiferromagnetic interactions between metal centers, and frequency-dependent out-of-phase (${\\chi {^\\prime}{^\\prime}_{\\rm{M}} }$) signals below 4 K suggest slow relaxation of magnetization. PMID:26295925

  8. 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 α-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

  9. Construction of Polynuclear Lanthanide (Ln = Dy(III), Tb(III), and Nd(III)) Cage Complexes Using Pyridine-Pyrazole-Based Ligands: Versatile Molecular Topologies and SMM Behavior.

    PubMed

    Bala, Sukhen; Sen Bishwas, Mousumi; Pramanik, Bhaskar; Khanra, Sumit; Fromm, Katharina M; Poddar, Pankaj; Mondal, Raju

    2015-09-01

    Employment of two different pyridyl-pyrazolyl-based ligands afforded three octanuclear lanthanide(III) (Ln = Dy, Tb) cage compounds and one hexanuclear neodymium(III) coordination cage, exhibiting versatile molecular architectures including a butterfly core. Relatively less common semirigid pyridyl-pyrazolyl-based asymmetric ligand systems show an interesting trend of forming polynuclear lanthanide cage complexes with different coordination environments around the metal centers. It is noteworthy here that construction of lanthanide complex itself is a challenging task in a ligand system as soft N-donor rich as pyridyl-pyrazol. We report herein some lanthanide complexes using ligand containing only one or two O-donors compare to five N-coordinating sites. The resultant multinuclear lanthanide complexes show interesting magnetic and spectroscopic features originating from different spatial arrangements of the metal ions. Alternating current (ac) susceptibility measurements of the two dysprosium complexes display frequency- and temperature-dependent out-of-phase signals in zero and 0.5 T direct current field, a typical characteristic feature of single-molecule magnet (SMM) behavior, indicating different energy reversal barriers due to different molecular topologies. Another aspect of this work is the occurrence of the not-so-common SMM behavior of the terbium complex, further confirmed by ac susceptibility measurement. PMID:26347289

  10. Evolution of the crystal and magnetic structure of the R2MnRuO7 (R = Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y) family of pyrochlore oxides.

    PubMed

    Martínez-Coronado, R; Retuerto, M; Fernández, M T; Alonso, J A

    2012-07-28

    The members of the family of pyrochlore oxides with the formula R(2)MnRuO(7) (R = Tb, Dy, Ho, Er, Tm, Yb, Lu and Y) have been synthesized and characterized. Polycrystalline samples were prepared by a soft chemistry procedure involving citrates of the different metal ions, followed by thermal treatments in air or O(2) pressure. The crystallographic and magnetic structures have been analysed from X-ray diffraction (XRD) and neutron powder diffraction (NPD) data, in complement with magnetic measurements; the evolution along the series of the crystallographic parameters (unit-cell parameters, bond distances and angles) is discussed. In R(2)MnRuO(7) pyrochlores, Mn and Ru ions statistically occupy the 16c sites in a cubic unit cell with space group Fd ̅3m, which defines an intrinsic frustrated three-dimensional system. In all the cases, the low-temperature NPD data unveils an antiferromagnetic coupling of two subsets of Mn(4+)/Ru(4+) spins, indicating that the magnetic frustration is partially relieved by the random distribution of Mn and Ru over the 16c sites. At lower temperatures there is a polarization of the R(3+) magnetic moments, which also participate in the magnetic structure, when a magnetic rare earth is present. PMID:22669397

  11. Simple correction for the sample shape and radial offset effects on SQUID magnetometers: Magnetic measurements on Ln{sub 2}O{sub 3} (Ln=Gd, Dy, Er) standards

    SciTech Connect

    Morrison, Gregory; Loye, Hans-Conrad zur

    2015-01-15

    An increased focus on magnetic measurements of oriented single crystals, thin films, and magnetically dilute systems has led to a demand for the measurement of weak magnetic moments. This level of sensitivity and precision can be achieved on SQUID magnetometers by decreasing the size of the detection coils. However, the smaller detection coils can amplify two errors in the magnitude of the measured moment, the sample shape and radial offset effects, which were small and typically unaccounted for on previous magnetometers. We report a simple method to determine the radial offset of a sample by taking advantage of the two basic scan modes, DC and lock-in, typically used on magnetometers. This technique allows for the correction of the sample shape and radial offset effects in order to obtain the true moment of a sample. To show the efficacy of this technique, we report the magnetic properties of Ln{sub 2}O{sub 3} (Ln=Gd, Dy, Er). - Graphical abstract: Correction for the sample shape and radial offset effects on SQUID magnetometers using a combination of DC and VSM scan data. - Highlights: • Sample shape and radial offset effects alter the moment measured by magnetometers. • We present a simple method to correct for these sample effects on magnetometers. • We measure magnetic susceptibilities of Ln{sub 2}O{sub 3} to show the efficacy of this method.

  12. Synthesis, thermogravimetric and 57Fe Mössbauer studies of the oxygen deficient perovskite REBaCuFeO 5 + x series (RE = Y, Nd, Sm, Gd, Dy, Tm, Lu)

    NASA Astrophysics Data System (ADS)

    Pissas, M.; Mitros, C.; Kallias, G.; Psycharis, V.; Simopoulos, A.; Kostikas, A.; Niarchos, D.

    1992-03-01

    We present the results of thermogravimetric and 57Fe Mössbauer studies of the oxygen deficient perovskite REBaCuFeO 5+x series with RE = Y, Nd, Sm, Gd, Dy, Tm, Lu. The presence of the removable content x of oxygen was determined by analysis of TGA measurements in a stream of Ar gas. The amount of removable oxygen was highest for the Nd compound and varied between 0.07 and 0.12 for the other compounds. By means of the Rietveld method we performed the refinement of the structure of the compounds, based on the space group P4mm, after taking into consideration that the Fe ion occupies the lb 1 ( z = 0.27) site and Cu the lb 2 ( z = 0.74) site. From the analysis of the Mössbauer spectra we found that the compounds become magnetically ordered with transition temperatures depending on the oxygen content. The values of the hyperfine parameters in all the samples indicate the ferric iron to be in a high spin state.

  13. Single-molecule magnet behavior and magnetocaloric effect in ferromagnetically coupled Ln(III)-Ni(II)-Ni(II)-Ln(III) (Ln(III) = Dy(III) and Gd(III)) linear complexes.

    PubMed

    Meseguer, Carlos; Titos-Padilla, Silvia; Hänninen, Mikko M; Navarrete, R; Mota, A J; Evangelisti, Marco; Ruiz, José; Colacio, Enrique

    2014-11-17

    New types of linear tetranuclear Ln(III)-Ni(II)-Ni(II)-Ln(III) (Ln(III) = Dy (1), Gd (2)) complexes have been prepared using the multidentate ligand N,N'-bis(3-methoxysalicylidene)-1,3-diaminobenzene, which has two sets of NO and OO' coordination pockets that are able to selectively accommodate Ni(II) and Ln(III) ions, respectively. The X-ray structure analysis reveals that the Ni(II) ions are bridged by phenylenediimine groups forming a 12-membered metallacycle in the central body of the complex, whereas the Ln(III) ions are located at both sides of the metallacycle and linked to the Ni(II) ions by diphenoxo bridging groups. Phenylenediimine and diphenoxo bridging groups transmit ferromagnetic exchange interactions between the two Ni(II) ions and between the Ni(II) and the Ln(III) ions, respectively. Complex 1 shows slow relaxation of the magnetization at zero field and a thermal energy barrier Ueff = 7.4 K with HDC = 1000 Oe, whereas complex 2 exhibits an S = 9 ground state and significant magnetocaloric effect (-ΔSm = 18.5 J kg(-1) K(-1) at T = 3 K and ΔB = 5 T). PMID:25350578

  14. Investigation of a new magnetic dipole mode in the heavy, deformed nuclei 154 Sm, 156 Gd, 158 Gd, 164 Dy, 168 Er, and 174 Yb with high resolution electron scattering

    NASA Astrophysics Data System (ADS)

    Bohle, Detlev

    A magnetic dipole mode in heavy, deformed nuclei is demonstrated using inelastic electron scattering with high energy resolution. The nuclei were investigated in an electron linear accelerator; additional measurements with inelastically scattered protons were conducted in a synchrocyclotron. A collective, magnetic dipole excitation is discovered in all nuclei, and characterized as an orbit mode. The measurements on 156 Gd show strong fragmentation of the magnetic dipole strength. The experimental results were explained using three models: the two-rotor model, the random phase approximation, and the interacting boson approximation. In a macroscopic picture, the models reveal the discovered mode as a magnetic analogy of the electric dipole resonance.

  15. Doxorubicin-conjugated β-NaYF4:Gd(3+)/Tb(3+) multifunctional, phosphor nanorods: a multi-modal, luminescent, magnetic probe for simultaneous optical and magnetic resonance imaging and an excellent pH-triggered anti-cancer drug delivery nanovehicle.

    PubMed

    Padhye, Preeti; Alam, Aftab; Ghorai, Suvankar; Chattopadhyay, Samit; Poddar, Pankaj

    2015-12-14

    Herein, we report the fabrication of a multifunctional nanoprobe based on highly monodispersed, optically and magnetically active, biocompatible, PEI-functionalized, highly crystalline β-NaYF4:Gd(3+)/Tb(3+) nanorods as an excellent multi-modal optical/magnetic imaging tool and a pH-triggered intracellular drug delivery nanovehicle. The static and dynamic photoluminescence spectroscopy showed the presence of sharp emission peaks, with long lifetimes (∼3.5 milliseconds), suitable for optical imaging. The static magnetic susceptibility measurements at room temperature showed a strong paramagnetic signal (χ∼ 3.8 × 10(-5) emu g(-1) Oe(-1)). The nuclear magnetic resonance (NMR) measurements showed fair T1 relaxivity (r1 = 1.14 s(-1) mM(-1)) and magnetic resonance imaging gave enhanced T1-weighted MRI images with increased concentrations of β-NaYF4:Gd(3+)/Tb(3+) making them suitable for simultaneous magnetic resonance imaging. In addition, an anticancer drug, doxorubicin (DOX) was conjugated to the amine-functionalized β-NaYF4:Gd(3+)/Tb(3+) nanorods via pH-sensitive hydrazone bond linkages enabling them as a pH-triggered, site-specific drug delivery nanovehicle for DOX release inside tumor cells. A comparison between in vitro DOX release studies undertaken in normal physiological (pH 7.4) and acidic (pH 5.0) environments showed an enhanced DOX dissociation (∼80%) at pH 5.0. The multifunctional material was also applied as an optical probe to confirm the conjugation of DOX and to monitor DOX release via a fluorescence resonance energy transfer (FRET) mechanism. The DOX-conjugated β-NaYF4:Gd(3+)/Tb(3+) nanorods exhibited a cytotoxic effect on MCF-7 breast cancer cells and their uptake by MCF-7 cells was demonstrated using confocal laser scanning microscopy and flow cytometry. The comparative cellular uptakes of free DOX and DOX-conjugated β-NaYF4:Gd(3+)/Tb(3+) nanorods were studied in tumor microenvironment conditions (pH 6.5) using confocal imaging, which showed an increased uptake of DOX-conjugated β-NaYF4:Gd(3+)/Tb(3+) nanorods. Thus, DOX-conjugated β-NaYF4:Gd(3+)/Tb(3+) nanorods combining pH-triggered drug delivery, efficient luminescence and paramagnetic properties are promising for a potential multifunctional platform for cancer therapy, biodetection, and optical and magnetic resonance imaging. PMID:26538278

  16. Neutron Study of the Magnetic Structures and Phase Transitions in RCuAs2 (R=Pr, Nd, Tb, Dy, Ho, Yb)

    NASA Astrophysics Data System (ADS)

    Zhao, Yang; Lynn, J. W.; Thakur, Gohil S.; Haque, Zeba; Gupta, L. C.; Ganguli, A. K.

    2015-03-01

    Neutron diffraction and inelastic scattering studies have been carried out on polycrystalline samples of the above titled materials as a function of temperature and applied magnetic field to determine the magnetic structures, order parameters, and overall spin dynamics. The space group of these compound is P4/nmm with typical (tetragonal) lattice parameters a ~ 3.9 Å and c ~ 10.0 Å. PrCuAs2 develops commensurate magnetic order at TN=6.4 K with an ordered moment of 1.24 μB oriented along the c-axis. The ordering wave vector is (0,0,1/2), with a Γ31 representation. NdCuAs2 orders at TN=3.54 K with the same ordering wave vector (with the Γ102 or Γ92 representations), but with the moment direction in the a-b plane along [110] of magnitude 3.5 μB. TbCuAs2 and HoCuAs2 exhibit incommensurate order at TN=9.1 and 4.0 K, respectively. The results for the inelastic scattering will be discussed.

  17. Metal-insulator transitions, structural and microstructural evolution of RNiO{sub 3} (R = Sm, Eu, Gd, Dy, Ho, Y) perovskites: Evidence for room-temperature charge disproportionation in monoclinic HoNiO{sub 3} and YNiO{sub 3}

    SciTech Connect

    Alonso, J.A.; Martinez-Lope, M.J.; Casais, M.T.; Arangda, M.A.G.; Fernandez-Diaz, M.T.

    1999-05-26

    RNiO{sub 3} nickelates have been prepared under high oxygen pressure (R = Sm, Eu, Gd) or high hydrostatic pressure (R = Dy, Ho, Y) in the presence of KClO{sub 4}. The samples have been investigated at room temperature (RT) by synchrotron X-ray powder diffraction to follow the evolution of the crystal structures and microstructures along the series. The distortion of the orthorhombic (space group Pbnm) perovskite progressively increases along the series, leading for the smallest Ho{sup 3+} and Y{sup 3+} cations to a subtle monoclinic distortion (space group P2{sub 1}/n) which implies the splitting of the Ni positions in the crystal. This symmetry was confirmed by neutron powder diffraction; the crystal structures for R = Ho and Y were refined simultaneously from RT synchrotron and neutron powder diffraction data. In both perovskites the oxygen octahedra around Ni1 and Ni2 positions are significantly distorted, suggesting the manifestation of Jahn-Teller effect, which is almost absent in the nickelates` of lighter rare earths. The very distinct mean Ni-O bond distances observed for Ni1 and Ni2 atoms at RT, in the insulating regime, suggest the presence of a charge disproportionation effect, considered as driving force for the splitting of the Ni positions. The metal-insulator (MI) transitions for RNiO{sub 3} (R = Gd, Dy, Ho, Y), above room temperature, have been characterized by DSC. The transition temperatures for Gd, Dy, Ho, and Y oxides in the heating runs are 510.7, 563.9, 572.7, and 581.9 K, respectively. The increasing rate of T{sub MI} for Dy, Ho, and Y materials is lower than that expected from the variation of T{sub MI} for the larger rare earth perovskites. This is probably related to the subtle monoclinic distortion found for Ho and Y nickelates. The high-resolution synchrotron X-ray powder patterns have revealed changes in the microstructure along the series. Powder patterns for orthorhombic RNiO{sub 3} (R = Sm, Eu, Gd, Dy) display asymmetric tails for some reflections which are due to structural mistakes such as stacking faults or regular intergrowths. These mistakes are not present in monoclinic RNiO{sub 3} (R = Ho, Y) nickelates.

  18. Doxorubicin-conjugated β-NaYF4:Gd3+/Tb3+ multifunctional, phosphor nanorods: a multi-modal, luminescent, magnetic probe for simultaneous optical and magnetic resonance imaging and an excellent pH-triggered anti-cancer drug delivery nanovehicle

    NASA Astrophysics Data System (ADS)

    Padhye, Preeti; Alam, Aftab; Ghorai, Suvankar; Chattopadhyay, Samit; Poddar, Pankaj

    2015-11-01

    Herein, we report the fabrication of a multifunctional nanoprobe based on highly monodispersed, optically and magnetically active, biocompatible, PEI-functionalized, highly crystalline β-NaYF4:Gd3+/Tb3+ nanorods as an excellent multi-modal optical/magnetic imaging tool and a pH-triggered intracellular drug delivery nanovehicle. The static and dynamic photoluminescence spectroscopy showed the presence of sharp emission peaks, with long lifetimes (~3.5 milliseconds), suitable for optical imaging. The static magnetic susceptibility measurements at room temperature showed a strong paramagnetic signal (χ ~ 3.8 × 10-5 emu g-1 Oe-1). The nuclear magnetic resonance (NMR) measurements showed fair T1 relaxivity (r1 = 1.14 s-1 mM-1) and magnetic resonance imaging gave enhanced T1-weighted MRI images with increased concentrations of β-NaYF4:Gd3+/Tb3+ making them suitable for simultaneous magnetic resonance imaging. In addition, an anticancer drug, doxorubicin (DOX) was conjugated to the amine-functionalized β-NaYF4:Gd3+/Tb3+ nanorods via pH-sensitive hydrazone bond linkages enabling them as a pH-triggered, site-specific drug delivery nanovehicle for DOX release inside tumor cells. A comparison between in vitro DOX release studies undertaken in normal physiological (pH 7.4) and acidic (pH 5.0) environments showed an enhanced DOX dissociation (~80%) at pH 5.0. The multifunctional material was also applied as an optical probe to confirm the conjugation of DOX and to monitor DOX release via a fluorescence resonance energy transfer (FRET) mechanism. The DOX-conjugated β-NaYF4:Gd3+/Tb3+ nanorods exhibited a cytotoxic effect on MCF-7 breast cancer cells and their uptake by MCF-7 cells was demonstrated using confocal laser scanning microscopy and flow cytometry. The comparative cellular uptakes of free DOX and DOX-conjugated β-NaYF4:Gd3+/Tb3+ nanorods were studied in tumor microenvironment conditions (pH 6.5) using confocal imaging, which showed an increased uptake of DOX-conjugated β-NaYF4:Gd3+/Tb3+ nanorods. Thus, DOX-conjugated β-NaYF4:Gd3+/Tb3+ nanorods combining pH-triggered drug delivery, efficient luminescence and paramagnetic properties are promising for a potential multifunctional platform for cancer therapy, biodetection, and optical and magnetic resonance imaging.Herein, we report the fabrication of a multifunctional nanoprobe based on highly monodispersed, optically and magnetically active, biocompatible, PEI-functionalized, highly crystalline β-NaYF4:Gd3+/Tb3+ nanorods as an excellent multi-modal optical/magnetic imaging tool and a pH-triggered intracellular drug delivery nanovehicle. The static and dynamic photoluminescence spectroscopy showed the presence of sharp emission peaks, with long lifetimes (~3.5 milliseconds), suitable for optical imaging. The static magnetic susceptibility measurements at room temperature showed a strong paramagnetic signal (χ ~ 3.8 × 10-5 emu g-1 Oe-1). The nuclear magnetic resonance (NMR) measurements showed fair T1 relaxivity (r1 = 1.14 s-1 mM-1) and magnetic resonance imaging gave enhanced T1-weighted MRI images with increased concentrations of β-NaYF4:Gd3+/Tb3+ making them suitable for simultaneous magnetic resonance imaging. In addition, an anticancer drug, doxorubicin (DOX) was conjugated to the amine-functionalized β-NaYF4:Gd3+/Tb3+ nanorods via pH-sensitive hydrazone bond linkages enabling them as a pH-triggered, site-specific drug delivery nanovehicle for DOX release inside tumor cells. A comparison between in vitro DOX release studies undertaken in normal physiological (pH 7.4) and acidic (pH 5.0) environments showed an enhanced DOX dissociation (~80%) at pH 5.0. The multifunctional material was also applied as an optical probe to confirm the conjugation of DOX and to monitor DOX release via a fluorescence resonance energy transfer (FRET) mechanism. The DOX-conjugated β-NaYF4:Gd3+/Tb3+ nanorods exhibited a cytotoxic effect on MCF-7 breast cancer cells and their uptake by MCF-7 cells was demonstrated using confocal laser scanning microscopy and flow cytometry. The comparative cellular uptakes of free DOX and DOX-conjugated β-NaYF4:Gd3+/Tb3+ nanorods were studied in tumor microenvironment conditions (pH 6.5) using confocal imaging, which showed an increased uptake of DOX-conjugated β-NaYF4:Gd3+/Tb3+ nanorods. Thus, DOX-conjugated β-NaYF4:Gd3+/Tb3+ nanorods combining pH-triggered drug delivery, efficient luminescence and paramagnetic properties are promising for a potential multifunctional platform for cancer therapy, biodetection, and optical and magnetic resonance imaging. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04473a

  19. An Undecanuclear Ferrimagnetic Cu9Dy2 Single Molecule Magnet Achieved through Ligand Fine-Tuning.

    PubMed

    Kühne, Irina A; Kostakis, George E; Anson, Christopher E; Powell, Annie K

    2016-05-01

    We describe the concept of increasing the nuclearity of a previously reported high-spin Cu5Gd2 core using a "fine-tuning" ligand approach. Thus, two Cu9Ln2 coordination clusters, with Ln = Dy (1) and Gd (2), were synthesized with the Gd compound having a ground spin state of (17)/2 and the Dy analogue showing single-molecule-magnet behavior in zero field. PMID:27096219

  20. A verification of the occurrence of the downconversion effect (transformation of a quantum of VUV radiation into two photons of luminescence in the visible range) in KGd2F7 and K2GdF5 crystals doped with Tb3+ ions

    NASA Astrophysics Data System (ADS)

    Makhov, V. N.; Khaidukov, N. M.

    2014-05-01

    In order to verify whether the downconversion mechanism can occur in KGd2F7 and K2GdF5 crystals, which contain different concentrations of Tb3+ ions, we have investigated the emission and luminescence-excitation spectra of these crystals. Our experimental results have not shown the occurrence of the downconversion effect in the examined crystals, since the rate of nonradiative relaxation from upper 4 f5 d levels to lower-lying 4 f5 d- and 4 f levels of the Tb3+ ion is likely to exceed the rate of possible cross relaxation from these high-lying 4 f5 d levels with energy transfer to neighboring Tb3+ ions.

  1. 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

  2. Spontaneous polarization and pyroelectric effect in the improper ferroelectrics-ferroelastics Gd2(MoO4)3 and Tb2(MoO4)3 at low temperatures

    NASA Astrophysics Data System (ADS)

    Matyjasik, S.; Shaldin, Yu. V.

    2013-11-01

    The experimental variations in the spontaneous polarization ΔPs(T) and pyroelectric coefficient γs(T) for Gd2(MoO4)3 (GMO) and Tb2(MoO4)3 (TMO) at low temperatures reported here differ from those for intrinsic ferroelectrics. A fundamental difference is found in the repolarization behavior of samples of GMO and TMO at fixed temperatures of 300 and 4.2 K. While the single domain formation temperature essentially has no effect on the measurements for TMO, a fundamental difference is observed in the case of GMO: single domain formation in the latter at 4.2 K leads to an order of magnitude increase in ΔPs at T > 85 K and distinct anomalies are observed in γs(T), at one of which the pyroelectric coefficient reaches a record peak of 3 × 10-4 C/(m2.K) at T = 25 K. At T = 200 K the pyroelectric coefficients equal -1.45 and -1.8 in units of 10-6 C/(m2.K). Based on these results and taking published data on the rotational structural transformation in the (001) plane and symmetry considerations into account, we propose a crystal physical model for GMO-type improper ferroelectrics consisting of four mesotetrahedra, each of which is made up of three different types (a, b, c) of MoO4 coordination tetrahedra. The physical significance of the pseudodeviator coefficient Q12*, which initiates the phase transition at T > 433 K from one non-centrally symmetric phase (mm2) into another (4¯2m), is discussed in terms of this model.

  3. 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.

  4. Polarized Raman and IR spectra of oriented Cd(0.9577)Gd(0.0282)□(0.0141)MoO4 and Cd(0.9346)Dy(0.0436)□(0.0218)MoO4 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

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

    SciTech Connect

    Kong, Tai; Bud'ko, Sergey L.; Jesche, Anton; McArthur, John; Kreyssig, Andreas; Goldman, Alan I.; Canfield, Paul C.

    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 300μΩ 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.

  6. Measurement of the 158Tb electron-capture Q value

    NASA Astrophysics Data System (ADS)

    Altzitzoglou, T.; Kouzes, R. T.; Loeser, F. W.; Lowry, M. M.; Naumann, R. A.; Chrien, R. E.

    1985-02-01

    An ultralow energy K-capture branch in the decay of 180-yr 158Tb has recently been suggested to offer very favorable energetics for investigating the electron neutrino mass. The 158Tb Q value relative to 158Gd has been measured by means of a (p,d) reaction on a radioactive 158Tb target. The ground state electron capture Q value of 1215.4(4.3) keV, inferred here, precludes 158Tb K electron capture to the 1187 keV state of 158Gd.

  7. Tuberculosis (TB)

    MedlinePlus

    ... Topics > Tuberculosis > Research Tuberculosis Understanding TB Research Research Goals Basic Research Diagnostic Research Advances in Treatment Prevention: Vaccine Development Global Research NIAID Labs Networks, Consortia, and Partners ...

  8. Lanthanide dinuclear complexes constructed from mixed oxygen-donor ligands: the effect of substituent positions of the neutral ligand on the magnetic dynamics in Dy analogues.

    PubMed

    Zhu, Wen-Hua; Li, Shan; Gao, Chen; Xiong, Xia; Zhang, Yan; Liu, Li; Powell, Annie K; Gao, Song

    2016-03-21

    Two series of lanthanide dinuclear complexes with the general formulae, [Ln(n-PNO)(Bza)3(H2O)] {Bza = benzoic acid; n = 3, n-PNO = 3-picoline N-oxide, Dy(1) and Er(2); and n = 4, n-PNO = 4-picoline N-oxide, Nd(3), Eu(4), Gd(5), Tb(6), Dy(7), Er(8) and Y(9)} have been successfully synthesized by the hydrothermal method. Single-crystal X-ray diffraction experiments illustrate that the two series of compounds possess similar carboxylic ligand-bridged dinuclear structure and coordination geometry around the lanthanide ions despite the different methyl-substituent positions on the neutral ligand. Comparative studies of the Dy analogues in the static-field measurements reveal only a little difference with a small butterfly-shaped opening for complex 1 and a close hysteresis loop for 7 at 2.0 K. However, systematic investigations of the alternating-current (ac) measurements indicate that the different substituent positions of the picoline N-oxide ligand have a significant effect on the magnetic relaxation dynamics. A more substantial suppression of the quantum tunnelling of magnetization (QTM) effect and pronounced slow magnetic relaxation were observed in complex 7 as compared to 1 under both zero and a 1 kOe static field. PMID:26847996

  9. Estimation of single ion anisotropy in pyrochlore Dy 2Ti 2O 7, a geometrically frustrated system, using crystal field theory

    NASA Astrophysics Data System (ADS)

    Jana, Y. M.; Sengupta, A.; Ghosh, D.

    2002-07-01

    From accurate measurement of magnetic susceptibility K¯ of powder sample and single crystal of cubic Dy 2Ti 2O 7 (DyT) between 300 and 70 K, a change of slope of 1/ K¯ was detected at 130 K because of crystal field (CF) effect. For analysing K¯, Mössbauer spectra and other available results on DyT consistently, the full form of the D 3d symmetry of CF was considered and J-mixing of the intermediately coupled states due to CF was done. The best fitted CF parameters were found as B 20=-880, B 40=-110, B 60=1040 , B 43=120, B 63=175, B 66=-1900 (all in cm -1). The corresponding multiplet of the ground 6H 15/2 has a lowest CF doublet level, well separated from the next doublet level (Δ˜100 cm-1) for which reason giant magnetostriction in DyT was not observed, unlike in TbT for which Δ˜12 cm-1. Using the best fitted electronic and nuclear energy patterns, different quantities were calculated, viz., the Curie constant, saturated magnetisation and saturated magnetic moment per Dy spin at low temperatures, the values of which were respectively, 9 emu K/g ion, 3.74×10 5 A/m, 4.7 μ B, being close to the measured values, g∥ value of ground doublet, which was reduced by ˜8% from the free ion value, and the quadrupolar interaction parameter, which was nearly zero at 110 K and attained a constant value of 1240±30 MHz at 4 K as observed. The hyperfine magnetic field Heff and the internal molecular field Hmol were found to be 540 and 0.2 T, respectively at 4 K. The calculated value of the single ion magnetic anisotropy Δ K at low temperature was larger in DyT compared to HoT. Calculations also showed that compared to the classical Heisenberg exchange interaction (HEI), the ferromagnetic n.n. dipolar interaction (FDI) dominates in DyT being respectively, 1.53 and 0.3 K, whereas in HoT and in GdT the ratio between these interactions are much reduced. The magnetic energy gains associated with FDI and HEI were calculated and found to be 1.66 and 0.6 K, respectively. The large values of Δ K and FDI, and weak HEI, are expected to make DyT a spin-ice system even at 0.2 K.

  10. 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

  11. Controlled synthesis and luminescence properties of Ca0.5Y1-x(MoO4)2:xRE3+ (RE = Eu, Pr, Sm, Tb, Dy, Yb/Er, Yb/Tm, and Yb/Ho) phosphors by hydrothermal method versus pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Mahalingam, Venkatakrishnan; Thirumalai, Jagannathan; Krishnan, Rajagopalan; Chandramohan, Rathinam

    2016-01-01

    Herein, we report on rare-earth (RE) activated Ca0.5Y1-x(MoO4)2:xRE3+ (RE = Eu, Pr, Sm, Tb, Dy, Yb/Er, Yb/Ho, and Yb/Tm) phosphors synthesized using a surfactant-mediated hydrothermal route. Timedependent experiments were performed, and the morphological evolution of the phosphors was studied. From prepared powder samples of Ca0.5Y1-x(MoO4)2:xRE3+ (RE = Eu and Yb/Er), nano-sized thin phosphor films were grown using pulsed laser deposition (PLD). The surface topography of the as-grown thin phosphor films was analyzed. The asprepared phosphors were characterized by structural and optical studies. The powder phosphor exhibited bi pyramid-like micro-architectures. Structural studies indicated that Ca0.5Y1-x(MoO4)2 possesses the scheelite tetragonal crystal structure. The down-conversion luminescence of Ca0.5Y1-x(MoO4)2:xRE3+ (RE = Eu, Pr, Sm, Tb, and Dy) as powder phosphors and Eu3+ doped Ca0.5Y1-x(MoO4)2 thin phosphor film were studied. Upon irradiation with a 980 nm laser, the Ca0.5Y1-x(MoO4)2: xRE3+ (RE = Yb/Er, Yb/Ho, and Yb/Tm) powder phosphors and Ca0.5Y1-x(MoO4)2:xRE3+ (RE = Yb/Er) thin phosphor film showed intense up-converted visible emissions in green, yellow, and blue regions. The fluorescence decay time and color co-ordinates were determined for all synthesized phosphors. From the obtained results, the prepared powder and thin film phosphors are suggested to be suitable candidates for display and electro-luminescence applications. [Figure not available: see fulltext.

  12. Crystal structure of {approx}RCu{sub 3}S{sub 3} and {approx}RCuTe{sub 2} (R=Gd-Lu) compounds

    SciTech Connect

    Gulay, L.D.; Daszkiewicz, M.; Shemet, V.Ya.

    2012-02-15

    The crystal structures of ternary compounds TbCu{sub 3}S{sub 3}, Dy{sub 1.06}Cu{sub 2.84}S{sub 3} (space group R3-bar), Ho{sub 0.67}Cu{sub 2}S{sub 2} (space group P3-bar m1), ErCu{sub 3}S{sub 3} (space group P3-bar 1c), Yb{sub 0.80}Cu{sub 1.60}S{sub 2}, Lu{sub 0.67}Cu{sub 2}S{sub 2}, TbCuTe{sub 2}, DyCuTe{sub 2}, Tm{sub 1.07}Cu{sub 0.78}Te{sub 2}, LuCuTe{sub 2} (space group P3-bar m1), Gd{sub 0.75}Cu{sub 1.74}Te{sub 2} (space group P3-bar 1m) were determined by means of X-ray single crystal diffraction. The S(Te) atoms are stacked in a close packed arrangement with the layers in the sequence AB. The R atoms are distributed over octahedral interstices whereas Cu atoms are located in tetrahedral interstices. Disorder of R and Cu atoms in studied chalcogenides is found. Crystal structure comparison showed that TbCuTe{sub 2} and DyCuTe{sub 2} crystallize as superstructure 2a Multiplication-Sign 2a Multiplication-Sign {sub 2}c to CaAl{sub 2}Si{sub 2} structure type, whereas Gd{sub 0.75}Cu{sub 1.74}Te{sub 2}, ErCu{sub 3}S{sub 3} and TbCu{sub 3}S{sub 3} (Dy{sub 1.06}Cu{sub 2.84}S{sub 3}) have superstructure {radical}3a Multiplication-Sign {radical}3a Multiplication-Sign nc with n=1, 2, 3. - Graphical abstract: In the series of the {approx}RCu{sub 3}S{sub 3} and {approx}RCuTe{sub 2} compounds the R and Cu atoms occupy disordered positions. The S(Te) atoms are stacked in a close packed arrangement with the layers in the sequence AB. Highlights: Black-Right-Pointing-Pointer The {approx}RCu{sub 3}S{sub 3} and {approx}RCuTe{sub 2} (R=Gd-Lu) crystallize with layered structure. Black-Right-Pointing-Pointer Superstructure {radical}3a Multiplication-Sign {radical}3a Multiplication-Sign nc (n=1, 2, 3) to CaAl{sub 2}Si{sub 2} structure type is found. Black-Right-Pointing-Pointer TbCuTe{sub 2} and DyCuTe{sub 2} crystallize as superstructure 2a Multiplication-Sign 2a Multiplication-Sign 2c. Black-Right-Pointing-Pointer Disorder of R and Cu atoms in studied chalcogenides is found.

  13. Structure and magnetic properties of rare-earth chromium germanides RECr xGe 2 ( RE=Sm, Gd-Er)

    NASA Astrophysics Data System (ADS)

    Bie, Haiying; Tkachuk, Andriy V.; Mar, Arthur

    2009-01-01

    The ternary rare-earth chromium germanides RECr xGe 2 ( RE=Sm, Gd-Er) have been obtained by reactions of the elements, either in the presence of tin or indium flux, or through arc-melting followed by annealing at 800 C. The homogeneity range is limited to 0.25? x?0.50 for DyCr xGe 2. Single-crystal and powder X-ray diffraction studies on the RECr 0.3Ge 2 members revealed that they adopt the CeNiSi 2-type structure (space group Cmcm, Z=4, a=4.1939(5)-4.016(2) , b=16.291(2)-15.6579(6) , c=4.0598(5)-3.9876(2) in the progression for RE=Sm to Er), which can be considered to be built up by stuffing transition-metal atoms into the square pyramidal sites of a " REGe 2" host with the ZrSi 2-type structure. (The existence of YbCr 0.3Ge 2 is also implicated.) Only the average structure was determined here, because unusually short Cr-Ge distances imply the development of a superstructure involving distortions of the square Ge net. Magnetic measurements on RECr 0.3Ge 2 ( RE=Gd-Er) indicated that antiferromagnetic ordering sets in below TN (ranging from 3 to 17 K), with additional transitions observed at lower temperatures for the Tb and Dy members.

  14. Discrete decay of the yrast superdeformed band in the {sup 151}Tb nucleus

    SciTech Connect

    Robin, J.; Duchene, G.; Beck, F. A.; Byrski, Th.; Curien, D.; Courtin, S.; Dorvaux, O.; Gall, B.; Nourredine, A.; Pachoud, E.; Piqueras, I.; Vivien, J. P.; Twin, P.; Cullen, D. M.; King, S. L.; Paul, E. S.; Adimi, N.; Appelbe, D. E.; Simpson, J.

    2008-09-15

    The Euroball array has been used to search for linking transitions between the superdeformed (SD) and the normal deformed (ND) wells in {sup 151}Tb. Many {gamma} rays in the energy range 2-4 MeV have been observed in coincidence with the yrast SD band. It is proposed that the highest energy transition of 3748 keV and the strongest line (2818 keV) of the previously observed transitions both decay from the same SD level as their links with the ND states have been identified. The current spectra have insufficient statistics to completely identify the decay point in the SD band. Theoretical calculations covering SD bands in the A{approx_equal}150 region enable the two possible spin assignments to be compared with experimental data on proposed links in {sup 149}Gd and {sup 152}Dy. It is concluded that the energy of the lowest SD band member in {sup 151}Tb has an excitation energy of 12861 keV and a spin of 65/2{sup +}.

  15. Ring-type electric current sensor based on ring-shaped magnetoelectric laminate of epoxy-bonded Tb{sub 0.3}Dy{sub 0.7}Fe{sub 1.92} short-fiber/NdFeB magnet magnetostrictive composite and Pb(Zr, Ti)O{sub 3} piezoelectric ceramic

    SciTech Connect

    Leung, Chung Ming; Or, Siu Wing; Zhang, Shengyao; Ho, S. L.

    2010-05-15

    A ring-type electric current sensor operated in vortex magnetic field detection mode is developed based on a ring-shaped magnetoelectric laminate of an axially polarized Pb(Zr, Ti)O{sub 3} (PZT) piezoelectric ceramic ring bonded between two circumferentially magnetized epoxy-bonded Tb{sub 0.3}Dy{sub 0.7}Fe{sub 1.92} (Terfenol-D) short-fiber/NdFeB magnet magnetostrictive composite rings. The electric current sensitivity of the sensor was evaluated, both theoretically and experimentally. The sensor showed a high nonresonance sensitivity of {approx}12.6 mV/A over a flat frequency range of 1 Hz-30 kHz and a large resonance sensitivity of 92.2 mV/A at the fundamental shape resonance of 67 kHz, besides an excellent linear relationship between the input electric current and the output magnetoelectrically induced voltage. The power-free, bias-free, high-sensitive, and wide-bandwidth natures of the sensor make it great potential for real-time condition monitoring of engineering systems having electric current-carrying cables or conductors.

  16. Magnetic ordering in the pyrochlore Ho{sub 2}CrSbO{sub 7} determined from neutron diffraction, and the magnetic properties of other RE{sub 2}CrSbO{sub 7} phases (RE=Y, Tb, Dy, Er)

    SciTech Connect

    Whitaker, Mariana J.; Greaves, Colin

    2014-07-01

    The magnetic structure of the pyrochlore Ho{sub 2}CrSbO{sub 7}, which orders magnetically below 13 K, has been studied using neutron powder diffraction. Ho{sub 2}CrSbO{sub 7} is found to form an “ordered spin-ice structure” where the magnetic moments are constrained along the 111 axes, but with a ferromagnetic moment in one direction. The Cr{sup 3+} ions order ferromagnetically and this is thought to lift the degeneracy of the x, y and z directions in the cubic structure causing the ferromagnetic component from the Ho{sup 3+} ions to align. The pyrochlores RE{sub 2}CrSbO{sub 7} where RE=Y, Tb, Dy and Er have also been prepared and studied using SQUID magnetometry. - Graphical abstract: The Ho magnetic moments align to provide an overall ferromagnetic moment along [001]. - Highlights: • Despite having inherent frustration on the Ho sublattice, Ho{sub 2}CrSbO{sub 7} orders ferromagnetically below 13 K. • Ordering on the Cr/Sb sublattice appears to remove the degenerate ground state for the Ho order. • The Ho{sup 3+} magnetic moments are aligned along <111> directions by crystal field effects. • Y{sub 2}CrSbO{sub 7} with diamagnetic Y{sup 3+} ions also has a ferromagnetic ground state.

  17. Reversible control of magnetic domains in a Tb0.3Dy0.7Fe2/Pt/PbZr0.56Ti0.44O3 thin film heterostructure deposited on Pt/TiO2/SiO2/Si substrate

    NASA Astrophysics Data System (ADS)

    More-Chevalier, J.; Ferri, A.; Cibert, C.; Poullain, G.; Desfeux, R.; Bouregba, R.

    2014-06-01

    Tb0.3Dy0.7Fe2/Pt/PbZr0.56Ti0.44O3 (Terfenol-D/Pt/PZT) magnetoelectric (ME) thin films were deposited on Pt/TiO2/SiO2/Si substrate. Ferroelectric and magnetic properties were characterized at room temperature. At zero dc magnetic field and out of mechanical resonance, a variation of the voltage across the ferroelectric film was obtained when a small external ac magnetic field was applied to the device. The corresponding ME voltage coefficient was 1.27 V/cm Oe. On the same sample, local magnetic domain patterns were imaged by magnetic force microscopy. Reversible changes in magnetic domain patterns were observed when a dc electric field of 120 to 360 kV/cm was applied to the ferroelectric layer. These results confirm that both magnetic control of ferroelectric polarization and electric control of magnetization are achievable on ME thin films devices deposited on silicon substrates.

  18. Gd3TCAS2: An Aquated Gd(3+)-Thiacalix[4]arene Sandwich Cluster with Extremely Slow Ligand Substitution Kinetics.

    PubMed

    Iki, Nobuhiko; Boros, Eszter; Nakamura, Mami; Baba, Ryo; Caravan, Peter

    2016-04-18

    In aqueous solution, Gd(3+) and thiacalix[4]arene-p-tetrasulfonate (TCAS) form the complex [Gd3TCAS2](7-), in which a trinuclear Gd(3+) core is sandwiched by two TCAS ligands. Acid-catalyzed dissociation reactions, as well as transmetalation and ligand exchange with physiological concentrations of Zn(2+) and phosphate, showed [Gd3TCAS2](7-) to be extremely inert compared to other Gd complexes. Luminescence lifetime measurements of the Tb analogue Tb3TCAS2 allowed estimation of the mean hydration number q to be 2.4 per Tb ion. The longitudinal relaxivity of [Gd3TCAS2](7-) (per Gd(3+)) was r1 = 5.83 mM(-1) s(-1) at 20 Hz (37 °C, pH 7.4); however, this relaxivity was limited by an extremely slow water exchange rate that was 5 orders of magnitude slower than the Gd(3+) aqua ion. Binding to serum albumin resulted in no relaxivity increase owing to the extremely slow water exchange kinetics. The slow dissociation and water exchange kinetics of [Gd3TCAS2](7-) can be attributed to the very rigid coordination geometry. PMID:27018719

  19. Tuberculosis (TB)

    MedlinePlus

    ... for the majority of TB cases in the United States every year since 2001. Moreover, the case rate among foreign-born persons in 2010 was approximately 11 times higher than among U.S.-born persons, according to the ... Links & Policies FOIA Employee Emergency Information ...

  20. IUPAC-NIST Solubility Data Series. 87. Rare Earth Metal Chlorides in Water and Aqueous Systems. Part 3. Heavy Lanthanides (Gd-Lu)

    NASA Astrophysics Data System (ADS)

    Mioduski, Tomasz; Gumiński, Cezary; Zeng, Dewen

    2009-12-01

    This is the third and last part of the volume devoted to solubility data of rare earth metal chlorides in water and in ternary and quaternary aqueous systems. Compilations of all available experimental data for each rare earth metal chloride are introduced with a corresponding critical evaluation. Every such evaluation contains a tabulated collection of all solubility results in water, a scheme of the water-rich part of the equilibrium LnCl3-H2O phase diagram, solubility equation(s), a selection of suggested solubility data, and a brief discussion of the multicomponent systems. Because the ternary and quaternary systems were almost never studied more than once, no critical evaluations or systematic comparisons of such data were possible. Simple chlorides (no complexes) of Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu are treated as the input substances. The literature (including a thorough coverage of papers in Chinese and Russian) has been covered through the middle of 2008.

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

    SciTech Connect

    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.

    2015-05-26

    We combined high field magnetization and magneto-optical spectroscopy to investigate spin-charge coupling in Mn-substituted rare-earth indium oxides of chemical formula RIn₁₋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 5d center.

  2. Location of trivalent lanthanide dopant energy levels in (Lu{sub 0.5}Gd{sub 0.5}){sub 2}O{sub 3}

    SciTech Connect

    Retot, H.; Viana, B.; Bessiere, A.; Galtayries, A.

    2011-06-15

    The location of Ln{sup 3+} dopant energy levels relative to bands in (Lu{sub 0.5}Gd{sub 0.5}){sub 2}O{sub 3} was studied. A several-steps analysis of XPS measurements on heavy lanthanides sesquioxides Ln{sub 2}O{sub 3} (Ln = Gd, Tb, Dy, Er, Tm, Yb, Lu) and on Sc{sub 2}O{sub 3} and Y{sub 2}O{sub 3} reference materials were used to locate Ln{sup 3+} dopant ground state relative to the top of the valence band in (Lu{sub 0.5}Gd{sub 0.5}){sub 2}O{sub 3} within an error bar of {+-}0.4 eV. The agreement between XPS data and model was found improved relative to previous studies. When compared to XPS analysis, prediction based on optical absorption shows a slight underestimation attributed to the lack of precision in Ce{sup 4+} charge transfer band measurement.

  3. Enhanced magnetostrictive effect in epoxy-bonded Tb{sub x}Dy{sub 0.9−x}Nd{sub 0.1}(Fe{sub 0.8}Co{sub 0.2}){sub 1.93} pseudo 1–3 particulate composites

    SciTech Connect

    Liu, J. J. E-mail: liujjimr@gmail.com; Pan, Z. B.; Song, X. H.; Zhang, Z. R.; Ren, W. J.

    2015-05-07

    The spin configuration and spontaneous magnetostriction λ{sub 111} of Tb{sub x}Dy{sub 0.9−x}Nd{sub 0.1}(Fe{sub 0.8}Co{sub 0.2}){sub 1.93} (0.20 ≤ x ≤ 0.60) alloys have been investigated. The easy magnetization direction (EMD) at room temperature was observed towards the 〈111〉 axis when 0.40 ≤ x ≤ 0.60, accompanied by a rhombohedral distortion with large spontaneous magnetostriction coefficients λ{sub 111}, which increases from 1640 ppm for x = 0.40 to 1900 ppm for x = 0.60. The strong 〈111〉-oriented pseudo 1–3 particulate composite was fabricated by embedding and aligning particles in a passive epoxy matrix under an applied magnetic field. An enhanced magnetostrictive effect, the large low-field magnetostriction, λ{sub a}, as high as 480 ppm at 3 kOe, was obtained for the sample of x = 0.40, in an excess of 75% of its polycrystalline alloy although it only contains 27 vol. % alloy particles. This enhanced effect can be attributed to its low magnetic anisotropy, anisotropic magnetostrictive nature (e.g., λ{sub 111} ≠ λ{sub 100,} 〈111〉EMD), chain structure, and the 〈111〉-textured orientation. In addition, we give a direct experimental support that the 〈111〉EMD of particle and the strong 〈111〉-textured orientation are the crucial factors to realize the enhanced magnetostrictive effect in 1–3 particulate composites.

  4. Dual-resonance converse magnetoelectric and voltage step-up effects in laminated composite of long-type 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 piezoelectric single-crystal transformer and Tb0.3Dy0.7Fe1.92 magnetostrictive alloy bars

    NASA Astrophysics Data System (ADS)

    Ming Leung, Chung; Wing Or, Siu; Wang, Feifei; Ho, S. L.

    2011-05-01

    We report a dual-resonance converse magnetoelectric effect and a dual-resonance voltage step-up effect in a laminated composite made by sandwiching the output (or secondary) section of a long-type 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 (PMN-PT) piezoelectric single-crystal transformer having a longitudinal-longitudinal polarization between two Tb0.3Dy0.7Fe1.92 (Terfenol-D) magnetostrictive alloy bars having a longitudinal magnetization. The reported converse magnetoelectric effect originates from the mechanically mediated resonance converse piezoelectric effect in the PMN-PT transformer and resonance converse magnetostrictive effect in the Terfenol-D bars. The additional voltage step-up effect results from the mechanically mediated resonance converse and direct piezoelectric effects in the PMN-PT transformer. The composite shows two sharp resonance peaks of 0.39 and 0.54 G/V in converse magnetoelectric coefficient (αB = dB/dVin) and of 1.4 and 2.1 in voltage step-up ratio (Vout/Vin) at about 54 and 120 kHz, corresponding to the half- and full-wavelength longitudinal mode resonances, respectively. The measured magnetic induction (B) exhibits good linear relationships to the applied ac voltage (Vin) with amplitude varying from 10 to 100 V in both resonance and nonresonance conditions. These dual-resonance effects make the composite great promise for coil-free electromagnetic device applications.

  5. 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.; Komatsu, T.

    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.

  6. Magnetic properties of Fe{sub 2}P-type Tb{sub 6}FeTe{sub 2}, Tb{sub 6}CoTe{sub 2}, Tb{sub 6}NiTe{sub 2} and Er{sub 6}FeTe{sub 2} compounds

    SciTech Connect

    Morozkin, A.V.; Mozharivskyj, Yu.; SvitlyK, V.; Nirmala, R.; Nigam, A.K.

    2010-12-15

    The magnetic ordering of the Fe{sub 2}P-type Tb{sub 6}FeTe{sub 2}, Tb{sub 6}CoTe{sub 2} Tb{sub 6}NiTe{sub 2} and Er{sub 6}FeTe{sub 2} phases (space group P6-bar 2m) has been investigated through magnetization measurement and neutron powder diffraction. Tb{sub 6}FeTe{sub 2}, Tb{sub 6}CoTe{sub 2} and Tb{sub 6}NiTe{sub 2} demonstrate high-temperature ferromagnetic and low-temperature spin reorientation transitions, whereas Er{sub 6}FeTe{sub 2} shows antiferromagnetic transition, only. The Tb{sub 6}FeTe{sub 2} and Tb{sub 6}NiTe{sub 2} phases show same high-temperature collinear ferromagnetic structure, whereas Tb{sub 6}FeTe{sub 2} is the commensurate non-collinear ferromagnet and Tb{sub 6}NiTe{sub 2} is the canted ferromagnetic cone with K{sub 1}=[0, 0, {+-}3/10] and K{sub 2}=[{+-}2/9, {+-}2/9, 0] wave vectors at 2 K. The magnetic structure of Er{sub 6}FeTe{sub 2} is a flat spiral with K{sub 1}=[0, 0, {+-}1/10] at 2 K. The magnetic entropy change for Tb{sub 6}NiTe{sub 2} is {Delta}S{sub m}=-4.86 J/kg K at 229 K for the field change {Delta}{mu}{sub 0}H=0-5 T. In addition, novel Fe{sub 2}P-type Gd{sub 6}FeTe{sub 2}, Zr{sub 6}FeTe{sub 2}, Hf{sub 6}FeTe{sub 2}, Dy{sub 6}NiTe{sub 2}, Zr{sub 6}NiTe{sub 2} and Hf{sub 6}NiTe{sub 2} phases have been obtained. -- Graphical abstract: The novel Fe{sub 2}P-type Tb{sub 6{l_brace}}Fe, Co, Te{r_brace}Te{sub 2} and Er{sub 6}FeTe{sub 2} phases (space group P6-bar 2m) show the complex magnetic ordering below 18-228 K. The magnetocaloric effect for Tb{sub 6}NiTe{sub 2} in terms of the isothermal entropy change, -{Delta}S{sub m}, has the maximum value of 4.86 J/kg K at 229 K for the 0-5 T field change.

  7. Tuberculosis Facts - Testing for TB

    MedlinePlus

    Tuberculosis (TB) Facts Testing for TB What is TB? “TB” is short for a disease called tuberculosis. TB is spread through the air from one ... Viral Hepatitis, STD, and TB Prevention Division of Tuberculosis Elimination

  8. Tuberculosis Facts - Exposure to TB

    MedlinePlus

    Tuberculosis (TB) Facts Exposure to TB What is TB? “TB” is short for a disease called tuberculosis. TB is spread through the air from one ... Viral Hepatitis, STD, and TB Prevention Division of Tuberculosis Elimination

  9. 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.

  10. 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; Gumiński, 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.

  11. Methane as a Selectivity Booster in the Arc-Discharge Synthesis of Endohedral Fullerenes: Selective Synthesis of the Single-Molecule Magnet Dy2TiC@C80 and Its Congener Dy2TiC2@C80.

    PubMed

    Junghans, Katrin; Schlesier, Christin; Kostanyan, Aram; Samoylova, Nataliya A; Deng, Qingming; Rosenkranz, Marco; Schiemenz, Sandra; Westerström, Rasmus; Greber, Thomas; Büchner, Bernd; Popov, Alexey A

    2015-11-01

    The use of methane as a reactive gas dramatically increases the selectivity of the arc-discharge synthesis of M-Ti-carbide clusterfullerenes (M=Y, Nd, Gd, Dy, Er, Lu). Optimization of the process parameters allows the synthesis of Dy2TiC@C80-I and its facile isolation in a single chromatographic step. A new type of cluster with an endohedral acetylide unit, M2TiC2@C80, is discovered along with the second isomer of M2TiC@C80. Dy2TiC@C80-(I,II) and Dy2TiC2@C80-I are shown to be single-molecule magnets (SMM), but the presence of the second carbon atom in the cluster Dy2TiC2@C80 leads to substantially poorer SMM properties. PMID:26350440

  12. 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.

  13. Global Tuberculosis (TB)

    MedlinePlus

    ... Diagnosis of TB Background General Considerations Research Needs Molecular Drug Susceptibility Tests (DSTs) Communication Plan for New ... Expert Panel Recommendations to ACET, CDC, DTBE Rapid Molecular Testing to Detect Drug-Resistant TB in the ...

  14. Search for neutrinoless double-electron capture of 156Dy

    NASA Astrophysics Data System (ADS)

    Finch, S. W.; Tornow, W.

    2015-12-01

    Background: Multiple large collaborations are currently searching for neutrinoless double-β decay, with the ultimate goal of differentiating the Majorana-Dirac nature of the neutrino. Purpose: Investigate the feasibility of resonant neutrinoless double-electron capture, an experimental alternative to neutrinoless double-β decay. Method: Two clover germanium detectors were operated underground in coincidence to search for the de-excitation γ rays of 156Gd following the neutrinoless double-electron capture of 156Dy. 231.95 d of data were collected at the Kimballton underground research facility with a 231.57 mg enriched 156Dy sample. Results: No counts were seen above background and half-life limits are set at O (1016-1018) yr for the various decay modes of 156Dy. Conclusion: Low background spectra were efficiently collected in the search for neutrinoless double-electron capture of 156Dy, although the low natural abundance and associated lack of large quantities of enriched samples hinders the experimental reach.

  15. Series of edge-sharing bi-triangle Ln4 clusters with a μ4-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(μ3-OH)2(μ4-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 μ4-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

  16. A two-step synthetic route to GdOF:Ln(3+) nanocrystals with multicolor luminescence properties.

    PubMed

    Shao, Baiqi; Feng, Yang; Jiao, Mengmeng; Lü, Wei; You, Hongpeng

    2016-02-14

    GdOF:Ln(3+) (Ln = Eu, Tb, Eu/Tb, Ce/Tb, Yb/Er, and Yb/Tm) nanocrystals with a hexagonal prism morphology have been readily synthesized by a novel topotactic transformation route. The Gd(OH)2F precursor was first synthesized and structurally analyzed by the Rietveld refinement method. It has been found that the Gd(OH)2F precursor was formed by a novel type of ion-exchange from the brucite-like Gd2(OH)5NO3·0.9H2O (LGdH). Such an ion-exchange behavior is different from the traditional case for the layered double hydroxides (LDHs) in which the intercalated anions are exchanged by the external ions. The detailed structural analysis showed that GdOF prefered [0001] epitaxial growth direction of Gd(OH)2F due to the structural matching of [0001]Gd(OH)2F//[110]GdOF. Furthermore, the potential application of the as-prepared nanocrystals as phosphors is emphasized by demonstrating strong multicolor emissions including both down-conversion and upconversion, and energy transfer (Ce-Tb) processes by GdOF:Ln(3+) in detail. Our nonorganic green synthetic strategy based on the novel ion-exchange for the LDHs may enrich the synthetic methodology for nanomaterials. PMID:26699240

  17. Difference Between Latent TB Infection and Active TB Disease

    MedlinePlus

    ... sick • • Cannot spread TB bacteria to others • • Needs treatment for latent TB infection to prevent TB disease; however, if exposed ... loss • • May spread TB bacteria to others • • Needs treatment to treat TB disease Additional Information 1. American Thoracic Society (ATS) ...

  18. Rotational structures and their evolution with spin in Gd152

    NASA Astrophysics Data System (ADS)

    Campbell, D. B.; Laird, R. W.; Riley, M. A.; Simpson, J.; Kondev, F. G.; Hartley, D. J.; Janssens, R. V. F.; Brown, T. B.; Carpenter, M. P.; Fallon, P.; Fischer, S. M.; Lauritsen, T.; Nisius, D.; Ragnarsson, I.

    2007-06-01

    The fusion-evaporation reaction involving a 175 MeV S36 beam and a Sn124 target was performed, and the emitted γ rays were observed with the Gammasphere spectrometer. Significant additions to the level scheme of Gd152 were made in spite of the relative weakness of the α4n exit channel, being only ˜2% of the total fusion cross-section. The high-spin behavior of Gd152 was compared with that of other N=88 nuclei. A striking similarity was observed with Dy154 and it is therefore suggested that the angular-momentum-induced shape changes that take place in Dy154 also occur in Gd152 in the 30 40ħ spin range. This is supported by Cranked Nilsson-Strutinsky calculations which were used to interpret the high-spin bands. It is found that a better agreement between calculation and experiment is obtained if the Z=64 shell gap increases with a decreasing number of valence particles outside the doubly-closed 64146Gd82 nucleus.

  19. 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

  20. TB Is Back.

    ERIC Educational Resources Information Center

    Natale, Jo Anna

    1992-01-01

    The reemergence of tuberculosis, particularly of new drug-resistant strains, points up the need for well-coordinated school health programs. Immigration effects, growing populations of HIV-infected persons, and relaxed screening procedures are partly responsible for TB's reemergence. Two sidebars offer advice on coping with TB at school and…

  1. TB Is Back.

    ERIC Educational Resources Information Center

    Natale, Jo Anna

    1992-01-01

    The reemergence of tuberculosis, particularly of new drug-resistant strains, points up the need for well-coordinated school health programs. Immigration effects, growing populations of HIV-infected persons, and relaxed screening procedures are partly responsible for TB's reemergence. Two sidebars offer advice on coping with TB at school and

  2. Synthesis And Characterization Of Gd2O3: Tb 30%

    NASA Astrophysics Data System (ADS)

    Djebara, Abdelhakim; Halimi, Rachid

    2008-09-01

    Over the past decade, nanotechnology has grown leading to the control of the synthesis and functionalization of nanoparticule for applications in the biological marking. The manufacture of nanoparticule luminescent intrinsically could move towards a single detection. By saving this very small optical signal, we can track the movement of the receptor in the membrane during unprecedented times, reaching overtime. This result is a significant advantage compared to the fluorescent molecules whose average lifespan is more limited. These particles can be detected by both the luminescence of rare earth ions present in the heart and that of organic fluorophore. The results look very encouraging. This work aims to study the development of nanoparticule of rare earth oxide as probes to monitor the dynamics of action unique biological entities. The goal of my work has been improved reproducibility of the synthesis and optimization protocol synthesis.

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

    SciTech Connect

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

    2015-03-16

    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 Fe{sub 82.89}Ga{sub 16.88}Tb{sub 0.23} 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 DO{sub 3} 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.

  4. Investigation on visible quantum cutting of Tb{sup 3+} in oxide hosts

    SciTech Connect

    Zhang, Jia Chen, Guibin; Wang, Yuhua; Huang, Yan

    2014-03-07

    Visible quantum cutting (QC) through downconversion was observed upon 4f{sup 8}-4f{sup 7}5d{sup 1} excitation of Tb{sup 3+} in both BaGdB{sub 9}O{sub 16} and Ca{sub 8}MgGd(PO{sub 4}){sub 7} compounds. The QC involves a cross relaxation process between two neighboring Tb{sup 3+}. Modified and new QC models are proposed based on the QC mechanisms in Gd{sup 3+}-Tb{sup 3+} system. Two calculation equations for the cross relaxation efficiency are suggested according to the energy transfer theory and spectral results. By studying the spectral characteristics of Tb{sup 3+} in hosts from fluoride to oxide, it indicates that the visible QC in Gd{sup 3+}-Tb{sup 3+} system may occur mainly depending on the structural features of phosphors, rather than the phonon energies of matrixes. All of the above conclusions have meaning of guidance for investigating other phosphors with QC phenomenon.

  5. Ternary aluminides R{sub 0.67}Ni{sub 2}Al{sub 6} (R=Sc, Y, Gd-Lu) with partly disordered structures

    SciTech Connect

    Matselko, Oksana; Pukas, Svitlana; Lutsyshyn, Yuriy; Gladyshevskii, Roman; Kaczorowski, Dariusz

    2013-02-15

    Ten rare-earth nickel aluminides R{sub 0.67}Ni{sub 2}Al{sub 6} (R=Sc, Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were synthesized by arc melting and their crystal structures studied by X-ray powder diffraction. They crystallize in the hexagonal structure type Yb{sub 0.67}Ni{sub 2}Al{sub 6}: Pearson symbol hP11-2.33, space group P-6m2, a=4.18904(2), c=9.09816(6) A, which can be decomposed into three kinds of layer. The sequence of layers along [001] is Yb{sub 0.67}Al-NiAl{sub 2}-Al-NiAl{sub 2}, but stacking faults appear due to relative shifts of consecutive Yb{sub 0.67}Al layers containing two rare-earth metal atoms for one Al-atom triangle. An ordered superstructure is the type ErNi{sub 3}Al{sub 9} (Pearson symbol hR78, space group R32, a={radical}(3)a{sub 0}, c=3c{sub 0}), refined on single crystals. The physical properties of the R{sub 0.67}Ni{sub 2}Al{sub 6} (R=Tb, Er, Tm, Yb, and Lu) compounds were determined by means of magnetic and electrical transport measurements. All these materials but Lu{sub 0.67}Ni{sub 2}Al{sub 6} exhibit Curie-Weiss paramagnetic behavior due to the trivalent R ions, and order magnetically at low temperatures. They show good metallic conductivity. The Yb-containing compound is a dense Kondo system with distinct features in the paramagnetic state of the interplay between Kondo and crystalline electric field interactions. - Graphical abstract: Stacking of layers along [001] in the Yb{sub 0.67}Ni{sub 2}Al{sub 6}-type structure. Highlights: Black-Right-Pointing-Pointer The aluminides R{sub 0.67}Ni{sub 2}Al{sub 6} (R=Sc, Y, Gd-Lu) adopt a partly disordered structure. Black-Right-Pointing-Pointer The structure is characterized by R{sub 2}Al{sub 3} layers with two R atoms for one Al{sub 3} triangle. Black-Right-Pointing-Pointer The compounds with R=Tb, Er, Tm are paramagnets at rt and order magnetically at lt. Black-Right-Pointing-Pointer The Yb-compound exhibits a magnetically ordered Kondo lattice with strong CEF effect.

  6. Rare earth metal rich magnesium compounds RE4NiMg ( RE=Y, Pr-Nd, Sm, Gd-Tm, Lu)—Synthesis, structure, and hydrogenation behavior

    NASA Astrophysics Data System (ADS)

    Tuncel, Selcan; Roquefère, Jean Gabriel; Stan, Cristina; Bobet, Jean-Louis; Chevalier, Bernard; Gaudin, Etienne; Hoffmann, Rolf-Dieter; Rodewald, Ute Ch; Pöttgen, Rainer

    2009-02-01

    The rare earth metal rich compounds RE4NiMg ( RE=Y, Pr-Nd, Sm, Gd-Tm, Lu) were synthesized from the elements in sealed tantalum tubes in an induction furnace. All compounds were investigated by X-ray diffraction on powders and single crystals: Gd 4RhIn type, space group F4¯3 m, Z=16, a=1367.6(2) pm for Y 4NiMg, a=1403.7(3) pm for Pr 4NiMg, a=1400.7(1) pm for Nd 4NiMg, a=1386.5(2) pm for Sm 4NiMg, a=1376.1(2) pm for Gd 4NiMg, a=1362.1(1) pm for Tb 4NiMg, a=1355.1(2) pm for Dy 4NiMg, a=1355.2(1) pm for Ho 4NiMg, a=1354.3(2) pm for Er 4NiMg, a=1342.9(3) pm for Tm 4NiMg, and a=1336.7(3) pm for Lu 4NiMg. The nickel atoms have trigonal prismatic rare earth coordination. These Ni RE6 prisms are condensed via common edges to a three-dimensional network which leaves voids for Mg 4 tetrahedra and the RE1 atoms which show only weak coordination to the nickel atoms. The single crystal data indicate two kinds of solid solutions. The RE1 positions reveal small RE1/Mg mixing and some compounds also show Ni/Mg mixing within the Mg 4 tetrahedra. Y 4NiMg and Gd 4NiMg have been tested for hydrogenation. These compounds absorb up to eleven hydrogen atoms per formula unit under a hydrogen pressure of 1 MPa at room temperature. The structure of the metal atoms is maintained with only an increase of the lattice parameters (Δ V/ V≈22%) if the absorption is done at T<363 K as at higher temperature a decomposition into REH 2- REH 3 hydrides occurred. Moreover, the hydrogenation affects drastically the magnetic properties of these intermetallics. For instance, Gd 4NiMg exhibits an antiferromagnetic behavior below T N=92 K whereas its hydride Gd 4NiMgH 11 is paramagnetic down to 1.8 K.

  7. Testing for TB Infection

    MedlinePlus

    ... for the Diagnosis of TB Background General Considerations Research Needs Molecular Drug Susceptibility Tests (DSTs) Communication Plan for New ... Possible Scenarios and Scope of Testing for a Molecular DR Testing Service Research Needs General Recommendations of the Expert Panel Communication ...

  8. Tuberculosis Facts - TB Can Be Treated

    MedlinePlus

    Tuberculosis (TB) Facts TB Can Be Treated What is TB? “TB” is short for a disease called tuberculosis. TB is spread through the air from one ... Viral Hepatitis, STD, and TB Prevention Division of Tuberculosis Elimination Page 1 of 2 TB Facts: TB ...

  9. Crystal structure of fluorite-related Ln{sub 3}SbO{sub 7} (Ln=La–Dy) ceramics studied by synchrotron X-ray diffraction and Raman scattering

    SciTech Connect

    Siqueira, K.P.F.; Borges, R.M.; Granado, E.; Malard, L.M.; Paula, A.M. de; Moreira, R.L.; Bittar, E.M.; Dias, A.

    2013-07-15

    Ln{sub 3}SbO{sub 7} (Ln=La, Pr, Nd, Sm, Eu, Gd, Tb and Dy) ceramics were synthesized by solid-state reaction in optimized conditions of temperature and time to yield single-phase ceramics. The crystal structures of the obtained ceramics were investigated by synchrotron X-ray diffraction, second harmonic generation (SHG) and Raman scattering. All samples exhibited fluorite-type orthorhombic structures with different oxygen arrangements as a function of the ionic radius of the lanthanide metal. For ceramics with the largest ionic radii (La–Nd), the ceramics crystallized into the Cmcm space group, while the ceramics with intermediate and smallest ionic radii (Sm–Dy) exhibited a different crystal structure belonging to the same space group, described under the Ccmm setting. The results from SHG and Raman scattering confirmed these settings and ruled out any possibility for the non-centrosymmetric C222{sub 1} space group describing the structure of the small ionic radii ceramics, solving a recent controversy in the literature. Besides, the Raman modes for all samples are reported for the first time, showing characteristic features for each group of samples. - Graphical abstract: Raman spectrum for La{sub 3}SbO{sub 7} ceramics showing their 22 phonon modes adjusted through Lorentzian lines. According to synchrotron X-ray diffraction and Raman scattering, this material belongs to the space group Cmcm. - Highlights: • Ln{sub 3}SbO{sub 7} ceramics belonging to the space groups Cmcm and Ccmm are synthesized. • SXRD, SHG and Raman scattering confirmed the orthorhombic structures. • Ccmm instead of C222{sub 1} is the correct one based on SHG and Raman data.

  10. 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(μ-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

  11. Scissors Mode of 162Dy Studied from Resonance Neutron Capture

    NASA Astrophysics Data System (ADS)

    Baramsai, B.; Bečvář, F.; Bredeweg, T. A.; Haight, R. C.; Jandel, M.; Kroll, J.; Krtička, M.; Mitchell, G. E.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Valenta, S.; Wilhelmy, J. B.

    2015-05-01

    Multi-step cascade γ-ray spectra from the neutron capture at isolated resonances of 161Dy nucleus were measured at the LANSCE/DANCE time-of-flight facility in Los Alamos National Laboratory. The objectives of this experiment were to confirm and possibly extend the spin assignment of s-wave neutron resonances and get new information on photon strength functions with emphasis on the role of the M1 scissors mode vibration. The preliminary results show that the scissors mode plays a significant role in all transitions between accessible states of the studied nucleus. The photon strength functions describing well our data are compared to results from 3He-induced reactions, (n,γ) experiments on Gd isotopes, and (γ,γ') reactions.

  12. Scissors Mode of 162 Dy Studied from Resonance Neutron Capture

    DOE PAGESBeta

    Baramsai, B.; Bečvář, F.; Bredeweg, T. A.; Haight, R. C.; Jandel, M.; Kroll, J.; Krtička, M.; Mitchell, G. E.; O’Donnell, J. M.; Rundberg, R. S.; et al

    2015-05-28

    Multi-step cascade γ-ray spectra from the neutron capture at isolated resonances of 161Dy nucleus were measured at the LANSCE/DANCE time-of-flight facility in Los Alamos National Laboratory. The objectives of this experiment were to confirm and possibly extend the spin assignment of s-wave neutron resonances and get new information on photon strength functions with emphasis on the role of the M1 scissors mode vibration. The preliminary results show that the scissors mode plays a significant role in all transitions between accessible states of the studied nucleus. The photon strength functions describing well our data are compared to results from 3He-induced reactions,more » (n,γ) experiments on Gd isotopes, and (γ,γ’) reactions.« less

  13. Tb/sub 2/Mn/sub 17/C/sub 3-x/ with filled Th/sub 2/Ni/sub 17/-type structure and some structural and magnetic properties of related compounds

    SciTech Connect

    Block, G.; Jeitschko, W.

    1987-10-01

    The new compounds R/sub 2/Mn/sub 17/C/sub 3-x/ (R = Y, Gd, Tb, Dy, Ho, Er, Tm, Lu) were prepared by reacting the elemental components in an arc-melting furnace with subsequent annealing at temperatures between 400 and 900/sup 0/C. Their crystal structures were determined from single-crystal x-ray diffractometer data of Tb/sub 2/Mn/sub 17/C/sub 3-x/ and refined to a residual of R = 0.035 for 27 variable parameters and 588 structure factors. It is hexagonal, space group P6/sub 3//mmc with the lattice constants a = 873.8(1) pm, c = 851.1(1) pm and Z = 2 formula units per cell. The positions of the metal atoms correspond to those of Th/sub 2/Ni/sub 17/. The carbon atoms are situated in approximately octahedral voids formed by two Tb and a rectangle of Mn atoms. Of these carbon positions 81 (4)% are occupied in the crystal investigated; this corresponds to the composition Tb/sub 2/Mn/sub 17/C/sub 2.43/. The new carbides CeMn/sub 11/C/sub 2-x/, NdMn/sub 11/C/sub 2-x/, ThMn/sub 11/C/sub 2-x/ crystallize with LaMn/sub 11/C/sub 2-x/ (filled BaCd/sub 11/) structure; Th/sub 2/Mn/sub 17/C/sub 3-x/ has Pr/sub 2/Mn/sub 17/C/sub 3-x/ (filled Th/sub 2/Zn/sub 17/) structure. The crystal chemistry of these and other interstitial carbides is discussed. The compounds LaMn/sub 11/C/sub 2-x/, CeMn/sub 11/C/sub 2-x/, Pr/sub 2/Mn/sub 17/C/sub 3-x/, and Tb/sub 2/Mn/sub 17/C/sub 3-x/ are paramagnetic with Curie-Weiss behavior at high temperature and no magnetic order at least above about 100 K. The Mn atoms carry magnetic moments in all four compounds. Down to 1.9 K no transition to a superconducting state could be observed for LaMn/sub 11/C/sub 2-x/, La/sub 2/Mn/sub 17/C/sub 3-x/, Y/sub 2/Mn/sub 17/C/sub 3-x/, or Lu/sub 2/Mn/sub 17/C/sub 3-x/.

  14. Magnetic and magneto-caloric properties of Tb5Ge2Si2

    NASA Astrophysics Data System (ADS)

    Tegus, O.; Dagula, O.; Brück, E.; Zhang, L.; de Boer, F. R.; Buschow, K. H. J.

    2002-05-01

    We have studied the magnetic properties and magneto-caloric effect in the compound Tb5Ge2Si2 by means of magnetic measurements. The compound Tb5Ge2Si2 is a canted antiferromagnet with Gd5Ge2Si2-type monoclinic structure. The ordering temperature is about 76 K. Above the ordering temperature, a field-induced first-order phase transition was observed in the magnetization curves with increasing and decreasing fields. The magnetic entropy changes have been calculated from the magnetization data based on the thermodynamic Maxwell relation. The character of the magnetic entropy changes, depending on the field and temperature, is similar to that in the Gd5Ge2Si2 compound. There is hardly any influence of the magnetic anisotropy on the magneto-caloric effects in Tb5Ge2Si2.

  15. 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.

  16. TB Screening Tests

    MedlinePlus

    ... services. Advertising & Sponsorship: Policy | Opportunities PLEASE NOTE: Your web browser does not have JavaScript enabled. Unless you enable Javascript , your ability to navigate and access the features of this website will be ... TB Screening Tests Share this page: Was this page helpful? Also ...

  17. Tuberculosis Facts - TB and HIV/AIDS

    MedlinePlus

    Tuberculosis (TB) Facts TB and HIV/AIDS What is TB? “TB” is short for a disease called tuberculosis. TB is spread through the air from one person to another. ... HIV) infection affect TB? The HIV, or the AIDS virus, helps TB germs make you sick because ...

  18. Tuberculosis Facts - You Can Prevent TB

    MedlinePlus

    Tuberculosis (TB) Facts You Can Prevent TB What is TB? “TB” is short for a disease called tuberculosis. TB is spread through the air from one person ... Division of Tuberculosis Elimination TB Facts: You Can Prevent TB What should I do if I have ...

  19. Substitution and liquid quenching effects on magnetic and magnetocaloric properties of (Gd1-xTbx)12Co7

    NASA Astrophysics Data System (ADS)

    Shishkin, D. A.; Baranov, N. V.; Volegov, A. S.; Gaviko, V. S.

    2016-02-01

    The influence of rapid quenching from the melt on the magnetic and magnetothermal properties of the (Gd1-xTbx)12Co7 samples has been investigated. The melt-spun (Gd1-xTbx)12Co7 alloys are observed to exhibit a ferromagnetic-like behavior and increased TC values at low Tb concentration in comparison with crystalline counterparts. The amorphization is suggested to result in the appearance of a small magnetic moment on Co atoms in Gd-rich liquid-quenched alloys. In low magnetic fields, the melt-spun (Gd1-xTbx)12Co7 alloys with high Tb concentrations exhibit enhanced values of the isothermal entropy change and refrigerant capacity then the crystalline compounds of the same composition.

  20. Rare earth metal rich magnesium compounds RE{sub 4}NiMg (RE=Y, Pr-Nd, Sm, Gd-Tm, Lu)-Synthesis, structure, and hydrogenation behavior

    SciTech Connect

    Tuncel, Selcan; Roquefere, Jean Gabriel; Stan, Cristina; Bobet, Jean-Louis Chevalier, Bernard Gaudin, Etienne; Hoffmann, Rolf-Dieter; Rodewald, Ute Ch; Poettgen, Rainer

    2009-02-15

    The rare earth metal rich compounds RE{sub 4}NiMg (RE=Y, Pr-Nd, Sm, Gd-Tm, Lu) were synthesized from the elements in sealed tantalum tubes in an induction furnace. All compounds were investigated by X-ray diffraction on powders and single crystals: Gd{sub 4}RhIn type, space group F4-bar 3m, Z=16, a=1367.6(2) pm for Y{sub 4}NiMg, a=1403.7(3) pm for Pr{sub 4}NiMg, a=1400.7(1) pm for Nd{sub 4}NiMg, a=1386.5(2) pm for Sm{sub 4}NiMg, a=1376.1(2) pm for Gd{sub 4}NiMg, a=1362.1(1) pm for Tb{sub 4}NiMg, a=1355.1(2) pm for Dy{sub 4}NiMg, a=1355.2(1) pm for Ho{sub 4}NiMg, a=1354.3(2) pm for Er{sub 4}NiMg, a=1342.9(3) pm for Tm{sub 4}NiMg, and a=1336.7(3) pm for Lu{sub 4}NiMg. The nickel atoms have trigonal prismatic rare earth coordination. These NiRE{sub 6} prisms are condensed via common edges to a three-dimensional network which leaves voids for Mg{sub 4} tetrahedra and the RE1 atoms which show only weak coordination to the nickel atoms. The single crystal data indicate two kinds of solid solutions. The RE1 positions reveal small RE1/Mg mixing and some compounds also show Ni/Mg mixing within the Mg{sub 4} tetrahedra. Y{sub 4}NiMg and Gd{sub 4}NiMg have been tested for hydrogenation. These compounds absorb up to eleven hydrogen atoms per formula unit under a hydrogen pressure of 1 MPa at room temperature. The structure of the metal atoms is maintained with only an increase of the lattice parameters ({delta}V/V{approx}22%) if the absorption is done at T<363 K as at higher temperature a decomposition into REH{sub 2}-REH{sub 3} hydrides occurred. Moreover, the hydrogenation affects drastically the magnetic properties of these intermetallics. For instance, Gd{sub 4}NiMg exhibits an antiferromagnetic behavior below T{sub N}=92 K whereas its hydride Gd{sub 4}NiMgH{sub 11} is paramagnetic down to 1.8 K. - Graphical abstract: The Mg{sub 4} and NiGd{sub 6} units in Gd{sub 4}NiMg and Gd{sub 4}NiMgH{sub x}.

  1. TB Summit 2014

    PubMed Central

    Maitra, Arundhati; Bhakta, Sanjib

    2014-01-01

    World TB Day commemorates Dr Robert Koch’s first announcement on March 24, 1882, that the bacterium Mycobacterium tuberculosis is the causative agent of tuberculosis. Currently, the event comprises of several conferences, meetings and activities held all over the world with the singular intention of raising public awareness about the global health emergency. In spite of having discovered the etiological agent of tuberculosis more than a century ago, a sizeable population still contract the disease every year and fall prey to it. In 2012, an estimated 8.6 million people developed the disease with 1.3 million succumbing to it. The number of TB deaths in children is unacceptably large, given that most are preventable. However, the challenge appears to be shifting toward attempts to control the rise and spread of the drug resistant variants of the microbe. To achieve this, a concerted effort from academia, clinical practice, and industry has been put forth. The TB Summit 2014 attempted to raise awareness as well as bring together experts involved in different aspects of tuberculosis research to help establish a more collective approach to battle this age-old disease. PMID:25003368

  2. 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.

  3. Ternary Dy-Er-Al magnetic refrigerants

    DOEpatents

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

    1995-07-25

    A ternary magnetic refrigerant material comprising (Dy.sub.1-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.

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

    SciTech Connect

    Gaulin, Bruce D.; Zhang, J.; Dahlberg, M. L.; Matthews, Maria J.; Bert, F.; Kermarrec, E.; Fritsch, Katharina; Granroth, Garrett E; Jiramongkolchai, P.; Amato, A.; Baines, C.; Cava, R. J.; Mendels, P.; Schiffer, P

    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.

  5. TB back with a vengeance.

    PubMed

    1993-11-15

    3 million deaths annually may be attributed to tuberculosis (TB), while 8 million new cases are added to the world each year. The major increase in the number of cases in the West, especially among those infected with HIV, and the emergence of drug-resistant strains have forced interested parties in the developed world to take another look at TB. An annual public health forum held at the London School of Hygiene and Tropical Medicine April 18-21, 1993, on TB called for extra investment in existing cost-effective tools against TB with research in the area a priority. Accountability and an interdisciplinary approach are needed. It was also expressed that national TB programs must provide affordable, well-managed treatment; diagnoses should be faster and be joined by active case-finding; patients' compliance should be encouraged and empowered; education should be targeted to a wide variety of groups involved in the fight against TB; commitment should be made to develop new drugs; appropriate interventions should be developed and implemented to prevent and manage TB among HIV-positive individuals; a new TB vaccine should be developed; political partnerships should be fostered; and measures adopted to fight poverty in the developing world. Finally, political will and cooperation are needed among private and public agencies in the fight against TB. PMID:12179170

  6. Binary amplitude holograms made from dyed photoresist.

    PubMed

    Wang, Quandou; Griesmann, Ulf; Burnett, John H

    2011-05-15

    A method for fabricating binary amplitude holograms from a dyed photoresist is described. It is of particular interest for holograms that are used as null optics in the form metrology of aspheric surfaces and wavefronts. A pigment that strongly absorbs light near 633 nm was dissolved in a positive photoresist and the dyed resist was spun onto silica glass substrates. Stable resist layers were obtained that were essentially opaque at 633 nm with little effect on the transmittance of the resist in the UV. A Fresnel zone plate was fabricated from the dyed resist layer using contact lithography, and its performance was demonstrated at 633 nm. PMID:21593928

  7. TB control: challenges and opportunities for India.

    PubMed

    Pai, Madhukar; Daftary, Amrita; Satyanarayana, Srinath

    2016-03-01

    India's TB control programme has treated over 19 million patients, but the incidence of TB continues to be high. TB is a major killer and drug-resistant TB is a growing threat. There are several likely reasons, including social conditions and co-morbidities that fuel the TB epidemic: under-investment by the government, weak programme implementation and management, suboptimal quality of care in the private sector, and insufficient advocacy around TB. Fortunately, India possesses the technical know-how, competence and resources to address these challenges. The End TB Strategy by WHO offers India an excellent blueprint to advance the agenda of TB control. PMID:26884494

  8. X-ray excited photoluminescence near the giant resonance in solid-solution Gd1-xTbxOCl nanocrystals and their retention upon solvothermal topotactic transformation to Gd1-xTbxF3.

    PubMed

    Waetzig, Gregory R; Horrocks, Gregory A; Jude, Joshua W; Zuin, Lucia; Banerjee, Sarbajit

    2015-12-23

    Design rules for X-ray phosphors are much less established as compared to their optically stimulated counterparts owing to the absence of a detailed understanding of sensitization mechanisms, activation pathways and recombination channels upon high-energy excitation. Here, we demonstrate a pronounced modulation of the X-ray excited photoluminescence of Tb(3+) centers upon excitation in proximity to the giant resonance of the host Gd(3+) ions in solid-solution Gd1-xTbxOCl nanocrystals prepared by a non-hydrolytic cross-coupling method. The strong suppression of X-ray excited optical luminescence at the giant resonance suggests a change in mechanism from multiple exciton generation to single thermal exciton formation and Auger decay processes. The solid-solution Gd1-xTbxOCl nanocrystals are further topotactically transformed with retention of a nine-coordinated cation environment to solid-solution Gd1-xTbxF3 nanocrystals upon solvothermal treatment with XeF2. The metastable hexagonal phase of GdF3 can be stabilized at room temperature through this topotactic approach and is transformed subsequently to the orthorhombic phase. The fluoride nanocrystals indicate an analogous but blue-shifted modulation of the X-ray excited optical luminescence of the Tb(3+) centers upon X-ray excitation near the giant resonance of the host Gd(3+) ions. PMID:26661920

  9. 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 (IFNγ)-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

  10. 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 (IFNγ)-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

  11. Synthesis and photoluminescence characteristics of Dy{sup 3+} doped NaY(WO{sub 4}){sub 2} phosphors

    SciTech Connect

    Liu, Xiaohua; Xiang, Wendou; Chen, Fengming; Hu, Zhengfa; Zhang, Wei

    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.

  12. Tuning interfacial domain walls in GdCo/Gd/GdCo' spring magnets

    NASA Astrophysics Data System (ADS)

    Blanco-Roldán, C.; Choi, Y.; Quirós, C.; Valvidares, S. M.; Zarate, R.; Vélez, M.; Alameda, J. M.; Haskel, D.; Martín, J. I.

    2015-12-01

    Spring magnets based on GdCo multilayers have been prepared to study the nucleation and evolution of interfacial domain walls (iDWs) depending on layer composition and interlayer coupling. GdCo alloy compositions in each layer were chosen so that their net magnetization aligns either with the Gd (G d35C o65 ) or Co (G d11C o89 ) sublattices. This condition forces an antiparallel arrangement of the layers' net magnetization and leads to nucleation of iDWs above critical magnetic fields whose values are dictated by the interplay between Zeeman and exchange energies. By combining x-ray resonant magnetic scattering with Kerr magnetometry, we provide detailed insight into the nucleation and spatial profile of the iDWs. For strong coupling (GdCo/GdCo' bilayer), iDWs are centered at the interface but with asymmetric width depending on each layer magnetization. When interlayer coupling is weakened by introducing a thin Gd interlayer, the exchange spring effect becomes restricted to a lower temperature and field range than observed in the bilayer structure. Due to the ferromagnetic alignment between the high magnetization G d35C o65 layer and the Gd interlayer, the iDW shrinks and moves into the lower exchange Gd interlayer, causing a reduction of iDW energy.

  13. Treatment: Latent TB Infection (LTBI) and TB Disease

    MedlinePlus

    ... for the Diagnosis of TB Background General Considerations Research Needs Molecular Drug Susceptibility Tests (DSTs) Communication Plan for New ... Possible Scenarios and Scope of Testing for a Molecular DR Testing Service Research Needs General Recommendations of the Expert Panel Communication ...

  14. An African woman with pulmonary cavities: TB or not TB?

    PubMed

    Delsing, C E; Ruesen, C; Boeree, M J; van Damme, P A; Kuipers, S; van Crevel, R

    2014-10-01

    Cavitary lung lesions in patients from developing countries are mostly caused by tuberculosis (TB). However, when TB cannot be confirmed, a primary lung abscess caused by anaerobic bacteria from the mouth should be considered, especially in patients with poor dentition. We present a case of a Sudanese woman with a cavitary lung lesion and severe gingivitis. Bulleidia extructa was isolated as a single pathogen from the pulmonary cavity. PMID:25387555

  15. X-ray excited photoluminescence near the giant resonance in solid-solution Gd1-xTbxOCl nanocrystals and their retention upon solvothermal topotactic transformation to Gd1-xTbxF3

    NASA Astrophysics Data System (ADS)

    Waetzig, Gregory R.; Horrocks, Gregory A.; Jude, Joshua W.; Zuin, Lucia; Banerjee, Sarbajit

    2015-12-01

    Design rules for X-ray phosphors are much less established as compared to their optically stimulated counterparts owing to the absence of a detailed understanding of sensitization mechanisms, activation pathways and recombination channels upon high-energy excitation. Here, we demonstrate a pronounced modulation of the X-ray excited photoluminescence of Tb3+ centers upon excitation in proximity to the giant resonance of the host Gd3+ ions in solid-solution Gd1-xTbxOCl nanocrystals prepared by a non-hydrolytic cross-coupling method. The strong suppression of X-ray excited optical luminescence at the giant resonance suggests a change in mechanism from multiple exciton generation to single thermal exciton formation and Auger decay processes. The solid-solution Gd1-xTbxOCl nanocrystals are further topotactically transformed with retention of a nine-coordinated cation environment to solid-solution Gd1-xTbxF3 nanocrystals upon solvothermal treatment with XeF2. The metastable hexagonal phase of GdF3 can be stabilized at room temperature through this topotactic approach and is transformed subsequently to the orthorhombic phase. The fluoride nanocrystals indicate an analogous but blue-shifted modulation of the X-ray excited optical luminescence of the Tb3+ centers upon X-ray excitation near the giant resonance of the host Gd3+ ions.Design rules for X-ray phosphors are much less established as compared to their optically stimulated counterparts owing to the absence of a detailed understanding of sensitization mechanisms, activation pathways and recombination channels upon high-energy excitation. Here, we demonstrate a pronounced modulation of the X-ray excited photoluminescence of Tb3+ centers upon excitation in proximity to the giant resonance of the host Gd3+ ions in solid-solution Gd1-xTbxOCl nanocrystals prepared by a non-hydrolytic cross-coupling method. The strong suppression of X-ray excited optical luminescence at the giant resonance suggests a change in mechanism from multiple exciton generation to single thermal exciton formation and Auger decay processes. The solid-solution Gd1-xTbxOCl nanocrystals are further topotactically transformed with retention of a nine-coordinated cation environment to solid-solution Gd1-xTbxF3 nanocrystals upon solvothermal treatment with XeF2. The metastable hexagonal phase of GdF3 can be stabilized at room temperature through this topotactic approach and is transformed subsequently to the orthorhombic phase. The fluoride nanocrystals indicate an analogous but blue-shifted modulation of the X-ray excited optical luminescence of the Tb3+ centers upon X-ray excitation near the giant resonance of the host Gd3+ ions. Electronic supplementary information (ESI) available: Actual and intended concentrations of incorporated Tb-dopants as determined from ICP-MS studies; optical absorption spectrum of Gd0.985Tb0.015OCl nanocrystals. See DOI: 10.1039/c5nr07819a

  16. Simulation of the magnetocaloric effect in Tb nanofilms

    SciTech Connect

    Anselmo, Dory Hélio A. L.; Mello, Vamberto D.; Vasconcelos, Manoel S.

    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 ΔT 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.

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

    MedlinePlus

    ... Understanding TB > What is TB? > Drug-Resistant TB Visual Tour Skip Website Tools Website Tools Print this ... Mycobacterium tuberculosis is from the Centers for Disease Control and Prevention , CDC/Dr. Ray Butler, Janice Carr. ...

  18. Electromagnetic transition strengths in Dy156

    NASA Astrophysics Data System (ADS)

    Möller, O.; Dewald, A.; Petkov, P.; Saha, B.; Fitzler, A.; Jessen, K.; Tonev, D.; Klug, T.; Heinze, S.; Jolie, J.; VonBrentano, P.; Bazzacco, D.; Ur, C. A.; Farnea, E.; Axiotis, M.; Lunardi, S.; De Angelis, G.; Napoli, D. R.; Marginean, N.; Martinez, T.; Caprio, M. A.; Casten, R. F.

    2006-08-01

    Reliable and precise lifetimes of excited states in Dy156 were measured by means of the recoil distance Doppler-shift technique in the coincidence mode. The experiment was performed at the Laboratori Nazionali di Legnaro with the GASP array and the Cologne coincidence plunger apparatus using the reaction Sn124(S36,4n)Dy156 at a beam energy of 155 MeV. New values of the branching ratios of transitions depopulating the levels of the first excited band have been derived. The measured transition probabilities of Dy156 in the ground-state band and the first excited band as well as the energy spectra are compared to the predictions of the recently proposed X(5) model and to an interacting boson approximation fit. The comparison reveals a different behavior of the intraband transition strengths and indicates a possible coexistence of a normal deformed ground-state band and an X(5)-like first excited band. It also reveals that in Dy156, the γ degree of freedom plays a more important role than it does in the well-established X(5) nuclei with N=90. A fit of the data using the general collective model suggests that a deeper collective potential V(β,γ) may also be a reason for the differences in the spectroscopic properties of Dy156 and those nuclei.

  19. Pentanuclear [2.2] spirocyclic lanthanide(III) complexes: slow magnetic relaxation of the Dy(III) analogue.

    PubMed

    Biswas, Sourav; Das, Sourav; van Leusen, Jan; Kögerler, Paul; Chandrasekhar, Vadapalli

    2015-11-28

    The reaction of LnCl3·6H2O (Ln = Dy(3+), Tb(3+) and Ho(3+)) with the multisite coordinating ligand N'-(2-hydroxy-3-(hydroxymethyl)-5-methylbenzylidene)acetohydrazide (LH3) in the presence of pivalic acid (PivH) leads to the formation of three isostructural homometallic pentanuclear complexes, [Dy5(LH)4(η(1)-Piv)(η(2)-Piv)3(μ2-η(2)η(1)Piv)2(H2O)]·Cl·9·5H2O·5MeOH (1), [Tb5(LH)4(η(1)-Piv)(η(2)-Piv)3(μ2-η(2)η(1)Piv)2(H2O)]·Cl·10.5H2O·2MeOH·2CHCl3 (2) and [Ho5(LH)4(η(1)-Piv)(η(2)-Piv)3(μ2-η(2)η(1)Piv)2(H2O)]·Cl·14.5H2O·2CHCl3 (3). 1-3 are monocationic and are comprised of four doubly deprotonated [LH](2-) ligands along with six pivalate ions. These complexes possess a [2.2] spirocyclic topology formed by the fusion of two triangles of Ln(III) ions at a common vertex. The magneto chemical analysis reveals the presence of antiferromagnetic exchange interactions at low temperature, and the Dy(III) complex 1 gives an out-of-phase signal with a small curvature in alternating current (ac) magnetic susceptibility measurement. Application of a 3000 G static field during ac measurement intensifies the signals, revealing a second slow relaxation process in the Dy(III) analogue. PMID:26489889

  20. TB deaths reach historic levels. International (global).

    PubMed

    More tuberculosis (TB)-related deaths occurred in 1995 than in any other year in history (almost 3 million, vs. 2.1 million for the TB epidemic around 1990). In the next 50 years, as many as 500 million people may develop TB if current rates continue. More and more of these people will develop multidrug resistant TB. TB affects all social groups. It is the leading fatal infection in youth and adults. HIV positive people are more likely to die from TB than any other condition. More women die from TB than all causes of maternal mortality combined. Almost 50% of the world's refugees may have TB. All people are at risk of TB since TB bacteria, which enter the air via coughing or sneezing, can be suspended in the air for hours. Increased air travel and migration have brought TB back to industrialized countries. Multi-drug resistant TB has emerged in New York City, London, Milan, Paris, Atlanta, Chicago, and cities in developing countries. Governments of industrialized and developing countries have been slow to understand the effects of multi-drug resistant TB for public health. During the 1970s and 1980s, TB was greatly neglected resulting in the current multi-drug resistant TB epidemic. Policy makers have not applied the tools discovered by scientists to help eliminate TB. The World Health Organization recommends directly observed treatment, short-course (DOTS) to fight TB. DOTS can increase the number of cured TB patients two-fold. It can cure almost 95% of TB patients with medicines costing less than $11 in some areas of the world. Yet DOTS is being used to cure only 10% of all TB patients in the world. If it were used in Bangladesh, Brazil, China, Ethiopia, India, Indonesia, Mexico, Nigeria, Pakistan, Russian Federation, South Africa, and Zaire, about 75% of all TB cases would be cured. In DOTS, health workers, not the TB patient, are responsible for curing the TB patient. Poor patient compliance is responsible for the current TB epidemic because TB patients remain contagious and infect others. PMID:12320054

  1. A comparative investigation of Lu2SiO5:Ce and Gd2O2S:Eu powder scintillators for use in x-ray mammography detectors

    NASA Astrophysics Data System (ADS)

    Michail, C. M.; Fountos, G. P.; David, S. L.; Valais, I. G.; Toutountzis, A. E.; Kalyvas, N. E.; Kandarakis, I. S.; Panayiotakis, G. S.

    2009-10-01

    The dominant powder scintillator in most medical imaging modalities for decades has been Gd2O2S:Tb due to the very good intrinsic properties and overall efficiency. Apart from Gd2O2S:Tb, there are alternative powder phosphor scintillators such as Lu2SiO5:Ce and Gd2O2S:Eu that have been suggested for use in various medical imaging modalities. Gd2O2S:Eu emits red light and can be combined mainly with digital mammography detectors such as CCDs. Lu2SiO5:Ce emits blue light and can be combined with blue sensitivity films, photocathodes and some photodiodes. For the purposes of the present study, two scintillating screens, one from Lu2SiO5:Ce and the other from Gd2O2S:Eu powders, were prepared using the method of sedimentation. The screen coating thicknesses were 25.0 and 33.1 mg cm-2 respectively. The screens were investigated by evaluating the following parameters: the output signal, the modulation transfer function, the noise equivalent passband, the informational efficiency, the quantum detection efficiency and the zero-frequency detective quantum efficiency. Furthermore, the spectral compatibility of those materials with various optical detectors was determined. Results were compared to published data for the commercially employed 'Kodak Min-R film-screen system', based on a 31.7 mg cm-2 thick Gd2O2S:Tb phosphor. For Gd2O2S:Eu, MTF data were found comparable to those of Gd2O2S:Tb, while the MTF of Lu2SiO5:Ce was even higher resulting in better spatial resolution and image sharpness properties. On the other hand, Gd2O2S:Eu was found to exhibit higher output signal and zero-frequency detective quantum efficiency than Lu2SiO5:Ce.

  2. Inelastic Neutron Scattering on 160Gd

    NASA Astrophysics Data System (ADS)

    Lesher, S. R.; Casarella, C.; Crider, B. P.; Ikeyama, R.; Marsh, I.; Peters, E. E.; Prados-Estévez, F. M.; Smith, M. K.; Tully, Z.; Vanhoy, J. R.; Aprahamian, A.; Yates, S. W.

    2014-03-01

    The nature of low-lying excitations, Kπ=0+ bands in deformed nuclei remain enigmatic in the field, especially in relationship to quadrupole vibrations. One method of characterizing these states beyond excitation energies is through measurements of absolute transition probabilities. In the rare earth region of deformation, there are five stable Gd isotopes, 154Gd, 156Gd, and 158Gd have been studied to obtain B(E2) values, a fourth, 160Gd is the focus of this work. We have examined 160Gd with the (n, n'γ) reaction and neutron energies up to 3.0 MeV to confirm known 0+ states.

  3. HIV-Associated TB: Facts 2013

    MedlinePlus

    ... Saharan Africa.  TB is the leading cause of death among people living with HIV, accounting for one in five HIV- related deaths. In 2012 some 320,000 people died of HIV-associated TB . Although globally the ...

  4. Staying on Track with TB Medicine

    MedlinePlus

    Staying on TB Track with Medicine TUBERCULOSIS What’s Inside: Read this brochure to learn about TB and what you can do to get ... TB disease 16 Section 4 PAGE Staying on track with your medicine plan 2 Your questions answered ...

  5. Cobalt-lanthanide coordination polymers constructed with metalloligands: a ferromagnetic coupled quasi-1D Dy3+ chain showing slow relaxation.

    PubMed

    Huang, You-Gui; Wang, Xiu-Teng; Jiang, Fei-Long; Gao, Song; Wu, Ming-Yan; Gao, Qiang; Wei, Wei; Hong, Mao-Chun

    2008-01-01

    Four types of cobalt-lanthanide heterometallic compounds based on metalloligand Co(2,5-pydc)(3) (3-) (2,5-H(2)pydc=pyridine-2,5-dicarboxylate acid), [Ln(2)Co(2)(2,5-pydc)(6)(H(2)O)(4)](n) 2n H(2)O (1) (Ln=Tb, Dy for 1 a, 1 b respectively), [Tb(2)Co(2)(2,5-pydc)(6)(H(2)O)(4)](n)3n H(2)O (2), [Tb(2)Co(2)(2,5-pydc)(6)(H(2)O)(9)](n)4n H(2)O (3), and [LaCo(2,5-pydc)(3)(H(2)O)(2)](n)2n H(2)O (4) have been synthesized. Compound 1 has a layer structure with well-isolated carboxylate-bridged Ln(3+) chains, compound 2 is a three-dimensional (3D) porous network with Tb(3+) chains that are also well isolated and carboxylate bridged, 3 is a layer structure based on dinuclear units, and 4 is a 3D network with boron nitride (BN) topology. DC magnetic studies reveal ferromagnetic coupling in all the carboxylate-bridged Ln(3+) chains in 1 a, 1 b, and 2. Compared to the silence of the out-of-phase ac susceptibility of 2, above 1.9 K the magnetic relaxation behavior of both 1 a and 1 b is slow like that of a single-chain magnet. PMID:18821536

  6. Magnetocaloric and magnetotransport properties in RRhSn (R = Tb-Tm) series

    NASA Astrophysics Data System (ADS)

    Gupta, Sachin B.; Suresh, K. G.; Nigam, A. K.

    2012-11-01

    We have synthesized polycrystalline RRhSn (R = Tb-Tm) compounds, which crystallize in the hexagonal structure with space group P62m. All the compounds, except HoRhSn, are antiferromagnetic at low temperatures. TbRhSn and DyRhSn show multiple magnetic transitions and metamagnetic behavior. Heat capacity and electrical resistivity data in different temperature regimes were fitted to identify various contributions to them. Magnetocaloric effect (MCE) in all the compounds has been calculated in terms of the isothermal magnetic entropy change and the adiabatic temperature change. ErRhSn and TmRhSn show Schottky anomaly in the heat capacity data. Among the compounds studied, HoRhSn shows the maximum adiabatic temperature change of 6.5 K for a field of 50 kOe. DyRhSn and TmRhSn also show large positive magnetocaloric effect below 10 K. A sign reversal accompanied by a large positive magnetoresistance (MR) at low temperatures appears to be a common feature in this series of compounds. Narrow domain wall dynamics appears to be the main reason behind the large positive magnetoresistance in all the compounds.

  7. Is TB in Your Curriculum?

    ERIC Educational Resources Information Center

    Kerr, Joanne; Elwell, Jack

    2002-01-01

    Points out the importance of effective health education to fight against tuberculosis (TB) which is the number one fatal infectious disease around the world. Describes a science curriculum on tuberculosis that includes information on the facts about tuberculosis, a forum on tuberculosis, and evaluation. (Contains 17 references.) (YDS)

  8. TB epidemiology and human genetics.

    PubMed

    van Helden, Paul D; Möller, Marlo; Babb, Chantal; Warren, Robin; Walzl, Gerhard; Uys, Pieter; Hoal, Eileen

    2006-01-01

    The impact of tuberculosis (TB) is considerably lower than one may expect, since in the absence of immunosuppression, fewer than 10% of infected individuals will develop active disease. The relatively low proportion of individuals who progress to active disease after infection can probably be ascribed to innate resistance in most infected individuals, since vaccination using BCG or a previous episode of TB does not work reliably or effectively to confer protection in high burden parts of the world. Innate factors affecting resistance or susceptibility can be modulated by the environment and such external influences cannot be ignored. Specifically, we will address bacterial variability as well as environmental factors such as diet, smoking, helminths and hormones. We will also discuss host genes that may be involved in susceptibility or resistance at various stages of infection or disease. The discovery of as yet unknown genes impacting on TB susceptibility or disease course may lead to new insights into mechanisms of disease and novel therapies. With adaptive immunity being of little value and good TB control programmes being rare, innate resistance is still our best defence against this PMID:17278383

  9. 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.

    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.

  10. Morphotropic phase boundary and magnetoelastic behaviour in ferromagnetic Tb1-xGdxFe2 system

    SciTech Connect

    Adil, Murtaza; Yang, Sen; Mi, Meng; Zhou, Chao; Wang, Jieqiong; Zhang, Rui; Liao, Xiaoqi; Wang, Yu; Ren, Xiaobing; Song, Xiaoping; Ren, Yang

    2015-03-30

    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 T-c. 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. (C) 2015 AIP Publishing LLC.

  11. Effect of gadolinium on the properties of Pr-Dy-Fe-Co-B materials

    NASA Astrophysics Data System (ADS)

    Kablov, E. N.; Ospennikova, O. G.; Piskorskii, V. P.; Rezchikova, I. I.; Valeev, R. A.; Korolev, D. V.

    2015-11-01

    Sintered (Pr1- x- y Dy x Gd y )13-14(Fe1- z Co z )balB6-7 materials ( x = 0.18-0.58, y = 0.05-0.33, z = 0.2-0.36) have been studied. The magnetic moments of gadolinium ions and those of the sublattice formed by Fe and Co ions are shown to be ordered antiferromagnetically. It is noted that an increase in the content of gadolinium, which substitutes for dysprosium, leads to an increase in residual induction B r , a decrease in coercive force H cJ , and an increase in the absolute value of the temperature coefficient of induction. The opposite effect takes place in the case of substitution of gadolinium for praseodymium in materials with a fixed dysprosium content.

  12. Scissors Mode of 162 Dy Studied from Resonance Neutron Capture

    SciTech Connect

    Baramsai, B.; Bečvář, F.; Bredeweg, T. A.; Haight, R. C.; Jandel, M.; Kroll, J.; Krtička, M.; Mitchell, G. E.; O’Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Valenta, S.; Wilhelmy, J. B.

    2015-05-28

    Multi-step cascade γ-ray spectra from the neutron capture at isolated resonances of 161Dy nucleus were measured at the LANSCE/DANCE time-of-flight facility in Los Alamos National Laboratory. The objectives of this experiment were to confirm and possibly extend the spin assignment of s-wave neutron resonances and get new information on photon strength functions with emphasis on the role of the M1 scissors mode vibration. The preliminary results show that the scissors mode plays a significant role in all transitions between accessible states of the studied nucleus. The photon strength functions describing well our data are compared to results from 3He-induced reactions, (n,γ) experiments on Gd isotopes, and (γ,γ’) reactions.

  13. Domain pinning and disorder in Fe/Gd magnetic multilayers.

    NASA Astrophysics Data System (ADS)

    Mohanty, Jyoti; Tripathi, Ashish; Shipton, Erik; Chan, Keith; Kim, Sangsoo; McNulty, Ian; Fullerton, Eric; Shpyrko, Oleg

    2009-03-01

    We study the evolution of magnetic domains and effect of pinning centers in thin film magnetic systems as a function of magnetic field, temperature, and dopants to identify the role the disorder in formation and stability of the domains in these systems. We have studied Fe/Gd multilayer exhibiting ordered stripes due to perpendicular magnetic anisotropy (PMA). Samples are well characterized using Polar Kerr effect and Vibrating sample magnetometry. Magnetic Force Microscopy (MFM) measurements show out-of-plane magnetized stripe domains. We study the effects of field pinning of the local magnetic structure of these systems through their magnetization hysteresis loops and their temperature driven dynamics. Using element sensitivity and depth resolution of resonant magnetic x-ray coherent scattering technique we investigate the magnetic domain structure and intermittent switching dynamics. Comparison of the magnetic speckles (in momentum space) provides information on correlation between the magnetic structures (in real space). We will present the X-ray Coherent Speckle Metrology approach to study of Barkhausen noise spectrum as a function of the applied magnetic field, and will discuss extension of this study to Tb-doped Fe/Gd magnetic films, which would induce strong PMA.

  14. Magnetic domain dynamics in Fe/Gd magnetic multilayers

    NASA Astrophysics Data System (ADS)

    Mohanty, Jyoti; Dietze, Sebastian; Tripathi, Ashish; Shipton, Erik; Chan, Keith; Kim, Sangsoo; McNulty, Ian; Fullerton, Eric; Shpyrko, Oleg

    2010-03-01

    We study the evolution of magnetic domains and effect of pinning centers in thin film magnetic systems as a function of magnetic field and dopants to identify the role the disorder in formation and stability of the domains in these systems. We have studied Fe/Gd multilayer exhibiting ordered stripes due to perpendicular magnetic anisotropy (PMA). Polar Kerr effect and Vibrating sample magnetometry measurements are used to characterize the sample. Magnetic Force Microscopy (MFM) measurements show out-of-plane magnetized stripe domains. We study the effects of field pinning of the local magnetic structure of these systems through their magnetization hysteresis loops both along easy and hard axis of magnetization. Using element sensitivity and depth resolution of resonant magnetic x-ray coherent scattering technique we investigate the magnetic domain structure and intermittent switching dynamics. Comparison of the magnetic speckles (in momentum space) provides information on correlation between the magnetic structures (in real space). We will present the X-ray Coherent Speckle Metrology approach to study Barkhausen noise spectrum as a function of the applied magnetic field, and will discuss extension of this study to Tb-doped Fe/Gd magnetic films.

  15. {beta}-Decay Half-Lives of New Neutron-Rich Isotopes of Elements from Pm to Tb

    SciTech Connect

    S. Ichikawa; M. Asai; K. Tsukada; A. Osa; M. Sakama; Y. Kojima; M. Shibata; I. Nishinaka; Y. Nagame; Y. Oura; K. Kawade

    1999-12-31

    Eight new neutron-rich lanthanide isotopes produced in the proton-induced fission of {sup 238}U have been identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport system. For six of these, each half-life was determined: {sup 159}Pm (2 {+-} 1 s), {sup 161}Sm (4.8 {+-} 0.8 s), {sup 165}Gd (10.3 {+-} 1.6 s), {sup 166}Tb (21 {+-} 6 s), {sup 167}Tb (19.4 {+-} 2.7 s) and {sup 168}Tb (8.2 {+-} 1.3 s). The observed half-lives were compared with theoretical calculations. The recent calculation by the gross theory with the new one-particle strength function shows quite good agreement with the experimental half-lives.

  16. {beta}-decay half-lives of new neutron-rich isotopes of elements from Pm to Tb

    SciTech Connect

    Ichikawa, S.; Asai, M.; Tsukada, K.; Nishinaka, I.; Nagame, Y.; Osa, A.; Sakama, M.; Oura, Y.; Kojima, Y.; Shibata, M.; Kawade, K.

    1999-11-16

    Eight new neutron-rich lanthanide isotopes produced in the proton-induced fission of {sup 238}U have been identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport system. For six of these, each half-life was determined: {sup 159}Pm (2{+-}1 s), {sup 161}Sm (4.8{+-}0.8 s), {sup 165}Gd (10.3{+-}1.6 s), {sup 166}Tb (21{+-}6 s), {sup 167}Tb (19.4{+-}2.7 s) and {sup 168}Tb (8.2{+-}1.3 s). The observed half-lives were compared with theoretical calculations. The recent calculation by the gross theory with the new one-particle strength function shows quite good agreement with the experimental half-lives.

  17. Near infrared emission of TbAG:Ce3+,Yb3+ phosphor for solar cell applications

    NASA Astrophysics Data System (ADS)

    Meshram, N. D.; Yadav, P. J.; Pathak, A. A.; Joshi, C. P.; Moharil, S. V.

    2016-05-01

    Luminescent materials doped with rare earth ions are used for many devices such as optical amplifiers in telecommunication, phosphors for white light emitting diodes (LEDs), displays, and so on. Recently, they also have attracted a great interest for photovoltaic applications to improve solar cell efficiency by modifying solar spectrum. Crystal silicon (c-Si) solar cells most effectively convert photons of energy close to the semiconductor band gap. The mis-match between the incident solar spectrum and the spectral response of solar cells is one of the main reasons to limit the cell efficiency. The efficiency limit of the c-Si has been estimated to be 29% by Shockley and Queisser. However, this limit is estimated to be improved up to 38.4% by modifying the solar spectrum by a quantum cutting (down converting) phosphor which converts one photon of high energy into two photons of lower energy. The phenomenon such as the quantum cutting or the down conversion of rare earth ions have been investigated since Dexter reported the possibility of a luminescent quantum yield greater than unity in 1957. In the past, the quantum cutting from a vacuum ultraviolet photon to visible photons for Pr3+, Gd3+,Gd3+-Eu3+, and Er3+-Tb3+ had been studied. Recently, a new quantum cutting phenomenon from visible photon shorter than 500 nm to two infrared photons for Tb3+-Yb3+, Pr3+-Yb3+, and Tm3+-Yb3+ has been reported. The Yb3+ ion is suitable as an acceptor and emitter because luminescent quantum efficiency of Yb3+ is close to 100% and the energy of the only excited level of Yb3+ (1.2 eV) is roughly in accordance with the band gap of Si (1.1 eV). In addition, the Ce3+-doped Tb3Al5O12 (TbAG), used as a phosphor for white LED, has broad absorption bands in the range of 300-500 nm due to strong ligand field and high luminescent quantum efficiency. Therefore, the Ce3+ ions in the TbAG can be suitable as an excellent sensitizing donor for down conversion materials of Si solar cells. In this paper, Ce3+ -Yb3+-codoped TbAG ceramics were prepared and the energy transfer (ET) including down conversion mechanism in Ce3+ - Yb3+ codoped TbAG ceramics have been evaluated by the photoluminescence (PL), the photoluminescence excitation (PLE), the lifetime and the quantum yield (QY), which was measured directly using an integrating sphere.

  18. 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.

  19. μ-Raman and infrared reflectance spectroscopy characterization of (Lu1-xGdx)2SiO5 solid solution single crystals doped with Dy3+ or Sm3+

    NASA Astrophysics Data System (ADS)

    Bińczyk, M.; Głowacki, M.; Łapiński, A.; Berkowski, M.; Runka, T.

    2016-04-01

    Single crystals of Lu2SiO5:5 at% Dy3+ - LSO:5Dy,(Lu0.6Gd0.4)2SiO5:4 at% Dy3+ - 60LGSO:4Dy and (Lu0.4Gd0.6)2SiO5:5 at% Sm3+ - 40LGSO:5Sm were obtained by the Czochralski method. It was found that the crystallographic structure of investigated crystals is isostructural with Lu2SiO5 which crystallizes in monoclinic system within a space group C2/c. Detailed spectroscopic analysis in a wide spectral region was carried out for these three solid solution crystals using two complementary techniques polarized Raman and infrared reflectance spectroscopy. Additional interesting information for the low-wavenumber range phonons were obtained using an NExT filter. The red shift of almost all modes with increasing gadolinium content was observed. It results from an increase in the lattice constants. The change in the splitting of the most intense symmetric stretching mode ν1 assigned to vibrations of SiO4 tetrahedra was observed with increasing gadolinium content. The spectral distance between the two components of this mode decreased from 23 cm-1 for LSO:5Dy through 20 cm-1 for 60LGSO:4Dy to 14 cm-1 for 40LGSO:5Sm. Analysis of vibrational spectra provides the information about structural changes and increase in crystal structure disorder with increasing gadolinium content. Increasing disorder observed in vibrational spectra indicates the possibility of substantial broadening of spectral lines of optically active ions in luminescence spectra.

  20. 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 β 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

  1. 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.

  2. Tunable luminescence of Dy3+ single-doped and Dy3+/Tm3+ co-doped tungsten borate glasses

    NASA Astrophysics Data System (ADS)

    Hu, J.; Gong, X. H.; Chen, Y. J.; Huang, J. H.; Lin, Y. F.; Luo, Z. D.; Huang, Y. D.

    2014-12-01

    RE3+ (RE3+ = Tm3+, Dy3+) ion single and co-doped tungsten borate glasses for white light emitting diodes (LEDs) were prepared by melt quenching method. Emission and excitation spectra of the glasses were measured. The color of luminescence can be tuned by changing the composition of glass matrix or the concentrations of Tm3+ and Dy3+ ions. White light emission can be achieved from 0.5Dy3+ single-doped 15WO3-25La2O3-60B2O3 and 0.4Tm3+/1.5Dy3+ co-doped 50WO3-25La2O3-25B2O3 glasses. In addition, energy transfers between Tm3+ and Dy3+ were also analyzed. The Dy3+/Tm3+ co-doped tungsten borate glasses may be potential candidates for white LED application.

  3. Energies, Wavelengths, and Transition Rates for Ga-Like Ions (Nd XXX-Tb XXXV)

    NASA Astrophysics Data System (ADS)

    El-Sayed, Fatma; Attia, S. M.

    2016-03-01

    Energies, wavelengths, transition probabilities, oscillator strengths, and line strengths have been calculated for 4s24p-4s4p2 and 4s24p-4s24d transitions in gallium-like ions from Z = 60 to 65, for Nd XXX, Pm XXXI, Sm XXXII, Eu XXXIII, Gd XXXIV, and Tb XXXV using the fully relativistic multiconfi guration Dirac-Fock method. The correlation with the n = 4 complex and the quantum electrodynamic effects have been considered in the calculations. The obtained results have been compared with the available experimental and other theoretical results.

  4. TB vaccine development and the End TB Strategy: importance and current status

    PubMed Central

    Fletcher, Helen A.; Schrager, Lewis

    2016-01-01

    TB is now the leading, global cause of death due to a single infectious microbe. To achieve the End TB vision of reducing TB by 90% by 2035 we will need new interventions. The objectives of this manuscript are to summarize the status of the clinical TB vaccine pipeline; to assess the challenges facing the TB development field; and to discuss some of the key strategies being embraced by the field to overcome these challenges. Currently, 8 of the 13 vaccines in clinical development are subunit vaccines; 6 of these contain or express either Ag85A or Ag85B proteins. A major challenge to TB vaccine development is the lack of diversity in both the antigens included in TB vaccines, and the immune responses elicited by TB vaccine candidates. Both will need to be expanded to maximise the potential for developing a successful candidate by 2025. Current research efforts are focused on broadening both antigen selection and the range of vaccine-mediated immune responses. Previous and ongoing TB vaccine efficacy trials have built capacity, generated high quality data on TB incidence and prevalence, and provided insight into immune correlates of risk of TB disease. These gains will enable the design of better TB vaccines and, importantly, move these vaccines into efficacy trials more rapidly and at a lower cost than was possible for previous TB vaccine candidates. PMID:27076508

  5. TB vaccine development and the End TB Strategy: importance and current status.

    PubMed

    Fletcher, Helen A; Schrager, Lewis

    2016-04-01

    TB is now the leading, global cause of death due to a single infectious microbe. To achieve the End TB vision of reducing TB by 90% by 2035 we will need new interventions. The objectives of this manuscript are to summarize the status of the clinical TB vaccine pipeline; to assess the challenges facing the TB development field; and to discuss some of the key strategies being embraced by the field to overcome these challenges. Currently, 8 of the 13 vaccines in clinical development are subunit vaccines; 6 of these contain or express either Ag85A or Ag85B proteins. A major challenge to TB vaccine development is the lack of diversity in both the antigens included in TB vaccines, and the immune responses elicited by TB vaccine candidates. Both will need to be expanded to maximise the potential for developing a successful candidate by 2025. Current research efforts are focused on broadening both antigen selection and the range of vaccine-mediated immune responses. Previous and ongoing TB vaccine efficacy trials have built capacity, generated high quality data on TB incidence and prevalence, and provided insight into immune correlates of risk of TB disease. These gains will enable the design of better TB vaccines and, importantly, move these vaccines into efficacy trials more rapidly and at a lower cost than was possible for previous TB vaccine candidates. PMID:27076508

  6. 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.

  7. Why healthcare workers are sick of TB.

    PubMed

    von Delft, Arne; Dramowski, Angela; Khosa, Celso; Kotze, Koot; Lederer, Philip; Mosidi, Thato; Peters, Jurgens A; Smith, Jonathan; van der Westhuizen, Helene-Mari; von Delft, Dalene; Willems, Bart; Bates, Matthew; Craig, Gill; Maeurer, Markus; Marais, Ben J; Mwaba, Peter; Nunes, Elizabete A; Nyirenda, Thomas; Oliver, Matt; Zumla, Alimuddin

    2015-03-01

    Dr Thato Mosidi never expected to be diagnosed with tuberculosis (TB), despite widely prevalent exposure and very limited infection control measures. The life-threatening diagnosis of primary extensively drug-resistant TB (XDR-TB) came as an even greater shock. The inconvenient truth is that, rather than being protected, Dr Mosidi and thousands of her healthcare colleagues are at an increased risk of TB and especially drug-resistant TB. In this viewpoint paper we debunk the widely held false belief that healthcare workers are somehow immune to TB disease (TB-proof) and explore some of the key factors contributing to the pervasive stigmatization and subsequent non-disclosure of occupational TB. Our front-line workers are some of the first to suffer the consequences of a progressively more resistant and fatal TB epidemic, and urgent interventions are needed to ensure the safety and continued availability of these precious healthcare resources. These include the rapid development and scale-up of improved diagnostic and treatment options, strengthened infection control measures, and focused interventions to tackle stigma and discrimination in all its forms. We call our colleagues to action to protect themselves and those they care for. PMID:25809771

  8. Spectroscopy of Gd153 and Gd157 using the (p,dγ) reaction

    DOE PAGESBeta

    Ross, T. J.; Hughes, R. O.; Allmond, J. M.; Beausang, C. W.; Angell, C. T.; Basunia, M. S.; Bleuel, D. L.; Burke, J. T.; Casperson, R. J.; Escher, J. E.; et al

    2014-10-31

    Low-spin single quasineutron levels in 153Gd and 157Gd have been studied following the 154Gd(p,d-γ )153Gd and 158Gd(p,d-γ )157Gd reactions. A combined Si telescope and high-purity germanium array was utilized, allowing d-γ and d-γ-γ 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. Lastly, 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.

  9. Registration of ‘Dy10-DLC’ wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dy10-DLC wheat (Triticum aestivum) was developed by USDA-ARS at the Western Regional Research Center in Albany, CA. Dy10-DLC was identified from an EMS-mutagenized population of an elite hexaploid wheat variety Summit by screening M3 seeds for altered storage protein profiles using one-dimensiona...

  10. 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.

    2013-06-10

    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 fieldsmore » 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.« less

  11. Ferromagnetic properties of fcc Gd thin films

    SciTech Connect

    Bertelli, T. P. Passamani, E. C.; Larica, C.; Nascimento, V. P.; Takeuchi, A. Y.

    2015-05-28

    Magnetic properties of sputtered Gd thin films grown on Si (100) substrates kept at two different temperatures were investigated using X-ray diffraction, ac magnetic susceptibility, and dc magnetization measurements. The obtained Gd thin films have a mixture of hcp and fcc structures, but with their fractions depending on the substrate temperature T{sub S} and film thickness x. Gd fcc samples were obtained when T{sub S} = 763 K and x = 10 nm, while the hcp structure was stabilized for lower T{sub S} (300 K) and thicker film (20 nm). The fcc structure is formed on the Ta buffer layer, while the hcp phase grows on the fcc Gd layer as a consequence of the lattice relaxation process. Spin reorientation phenomenon, commonly found in bulk Gd species, was also observed in the hcp Gd thin film. This phenomenon is assumed to cause the magnetization anomalous increase observed below 50 K in stressed Gd films. Magnetic properties of fcc Gd thin films are: Curie temperature above 300 K, saturation magnetization value of about 175 emu/cm{sup 3}, and coercive field of about 100 Oe at 300 K; features that allow us to classify Gd thin films, with fcc structure, as a soft ferromagnetic material.

  12. Neutron cross sections for /sup 152/Gd and /sup 153/Gd

    SciTech Connect

    Holden, N.E.

    1986-01-01

    Cross section data is tabulated for /sup 152/Gd and /sup 153/Gd. Resonance data is given for /sup 152/Gd. Both reported and revised measurements are presented for cross sections and resonance parameters. Recommendations for further cross section and resonance research for these two isotopes are made. (DWL). 15 ref., 3 tabs.

  13. TB in Correctional Facilities Is a Public Health Concern

    MedlinePlus

    ... Button Past Emails CDC Features TB in Correctional Facilities is a Public Health Concern Recommend on Facebook ... Figure 1 (larger view). TB Control in Correctional Facilities Diagnosing and treating TB in correctional facilities reduces ...

  14. Luminescence characteristics of K2Ca2(SO4)(3): Eu,Tb micro- and nanocrystalline phosphor

    NASA Astrophysics Data System (ADS)

    Salah, N.; Sahare, P. D.; Nawaz, S.; Lochab, S. P.

    2004-05-01

    K2Ca2(SO4)(3) microcrystalline pure, doped with Eu, Tb and co-doped with Eu, Tb was prepared by solid-state diffusion method. Nanoparticles of these phosphors were also prepared by the chemical co-precipitation method. The formation of the compounds was confirmed by XRD. The particle size was calculated by broadening of the XRD peaks using Scherrer's formula. The particle size of nanocrystalline powder material was approximately found to be around 20 nm. Thermoluminescence and photoluminescence were studied to see the effect of co-doping and particle size. Tb3+ co-doping decreases the intensity in the Eu2+ doped phosphor due to the energy transfer and multiple de-excitations through various radiative and non-radiative processes. The sensitivity of K2Ca2(SO4)(3):Eu,Tb microcrystalline phosphor was around 15 times more than LiF-TLD 100 and 7 times more than CaSO4:Dy. A high temperature peak (615 K) was observed in case of the nanoparticles, which was attributed to a particle size induced phase transition. This was confirmed by differential scanning calormetry measurements. The decrease in the sensitivity in case of nanoparticles is attributed to the particle size effect i.e. volume to surface ratio. Theoretical analysis of the glow curves was done by glow curve convolution deconvolution method to calculate trapping parameters of various peaks.

  15. Low-temperature nuclear orientation of160Tb in Tb/Fe multilayers

    NASA Astrophysics Data System (ADS)

    Trhlik, Miloš; de Moor, Piet; Pari, Patrick; Rotter, Miloš; Severijns, Nathal; van Geert, Anja; Vanneste, Ludo

    1996-04-01

    Magnetic moment direction of Tb in [Fe(40 Å)/Tb(x Å)]30 multilayers (x=20 and 10) has been studied by the low-temperature nuclear orientation technique in the temperature range of 5-50 mK and in the external magnetic field (Bext) range of 0-1 T, applied along the sample plane. The γ-ray anisotropy of the 299 keV160Tb line was monitored. The perpendicular magnetic anisotropy (PMA) of the Tb magnetic moments has been found at zero B ext for both systems. The PMA effect increased when the Tb layer thickness decreased.

  16. Minor planet 1983TB - A dead comet?

    NASA Technical Reports Server (NTRS)

    Cochran, A. L.; Barker, E. S.

    1984-01-01

    IDS spectra of the Apollo asteroid 1983TB wer obtained at McDonald Observatory on Dec. 2, 1983 UT. These spectra were examined for cometary-type emissions and none were found. The reflectance of 1983TB was found to be similar to an S-type asteroid.

  17. Encapsulation of radioactive [sup 159]Gd and [sup 161]Tb atoms in fullerene cages

    SciTech Connect

    Kikuchi, Koichi; Kobayashi, Kanako; Sueki, Keisuke; Suzuki, Shinzo; Nakahara, Hiromichi; Achiba, Yohji; Katada, Motomi ); Tomura, Kenji )

    1994-10-19

    We demonstrate a novel form of metallofullerenes, namely, those with radioactive atoms encapsulated in the C[sub 82]cage. The metal atoms were made radioactive by a neutron capture reaction or through a nuclear decay process. The most important and intriguing finding of the present study is that the endohedral form of metallofullerenes is not affected by the recoil energy of the metal atom resulting from emission of electrons in the [beta] decay. Such a stability of the cage against the recoil energy of the encapsulated atom was confirmed by the elution behavior of the metallofullerene in liquid chromatography. Successful encapsulation of radioactive atoms inside the fullerene cage will greatly widen the potential use of endohedral metallofullerenes not only in basic science and technology but also in other areas, such as medicine. 14 refs., 3 figs.

  18. Estimating the cost of TB and its social impact on TB patients and their households

    PubMed Central

    Onazi, O.; Gidado, M.; Onazi, M.; Daniel, O.; Kuye, J.; Obasanya, O.; Odusote, T.; Gande, S.

    2015-01-01

    Illness often poses a significant financial burden on individuals and their households, and tuberculosis (TB) is no exception. Although TB treatment is free in Nigeria, patients are likely to incur costs due to multiple visits during treatment. The purpose of this study was 1) to examine the health-seeking behaviour of TB patients and the costs borne by TB patients in Nigeria, and 2) to assess the social impact of TB disease on TB patients and their families/households. Of 260 TB patients surveyed, the majority (74.7%) were aged between 20 and 49 years. TB patients expended an average of US$52.02 (N = 8323.58, at the rate of US$1 = N = 160) per person on all visits associated with diagnosis and receipt of diagnostic test results. Overall, households experienced a shortfall of about US$57.30 (N = 9174.72) or 24.9% of income loss due to TB illness. Further analysis revealed that 9.7% of TB patients relied on children of school age or below to finance the costs of TB illness. PMID:26400384

  19. Magnetoresistance in nanostructured Tb/Ti and Tb/Si multilayers

    SciTech Connect

    Svalov, A. V.; Kurlyandskaya, G. V.; Vas'kovskiy, V. O.; Sorokin, A. N.; Diercks, D.

    2011-01-15

    Magnetic, magnetoresistive and structural properties were studied for [Tb/Ti]{sub n} and [Tb/Si]{sub n} multilayers which were prepared by rf-sputtering. The thickness of the Tb layers varied from 1.5 to 12 nm. The thickness of 2 nm nonmagnetic spacers of Ti or Si was kept constant. Both anisotropic and isotropic magnetoresistance was observed in [Tb/Ti]{sub n} and [Tb/Si]{sub n} multilayers. A decrease in the thickness of the terbium layers led to a decrease in the anisotropic contribution to the total magnetoresistance. The negative isotropic magnetoresistanse in [Tb/Ti]{sub n} and [Tb/Si]{sub n} multilayers can be attributed to the giant magnetoresistance (GMR) and/or high field isotropic magnetoresistance. The structure of the samples of both types enabled the existence of the GMR effect.

  20. 26 CFR 48.4082-2 - Diesel fuel and kerosene; notice required for dyed fuel.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... dyed fuel. 48.4082-2 Section 48.4082-2 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE... required for dyed fuel. (a) In general. A legible and conspicuous notice stating “DYED DIESEL FUEL... facility where it sells dyed diesel fuel for use by its buyer. A legible and conspicuous notice...

  1. 26 CFR 48.4082-2 - Diesel fuel and kerosene; notice required for dyed fuel.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... dyed fuel. 48.4082-2 Section 48.4082-2 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE... required for dyed fuel. (a) In general. A legible and conspicuous notice stating “DYED DIESEL FUEL... facility where it sells dyed diesel fuel for use by its buyer. A legible and conspicuous notice...

  2. 26 CFR 48.4082-2 - Diesel fuel and kerosene; notice required for dyed fuel.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... dyed fuel. 48.4082-2 Section 48.4082-2 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE... required for dyed fuel. (a) In general. A legible and conspicuous notice stating “DYED DIESEL FUEL... facility where it sells dyed diesel fuel for use by its buyer. A legible and conspicuous notice...

  3. 26 CFR 48.4082-2 - Diesel fuel and kerosene; notice required for dyed fuel.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... dyed fuel. 48.4082-2 Section 48.4082-2 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE... required for dyed fuel. (a) In general. A legible and conspicuous notice stating “DYED DIESEL FUEL... facility where it sells dyed diesel fuel for use by its buyer. A legible and conspicuous notice...

  4. Magnetic ordering in Gd5Ir2Bi and Gd5Ir2Sb

    NASA Astrophysics Data System (ADS)

    Ryan, D. H.; Mas, Nadejda; Rejali, Rasa; Miller, T.; Gerke, Birgit; Heying, Birgit; Pöttgen, Rainer; Flacau, Roxana

    2016-05-01

    155Gd Mössbauer spectroscopy and neutron powder diffraction have been used to study magnetic ordering in Gd5Ir2Bi and Gd5Ir2Sb. Despite the hyperfine fields (Bhf) at the two Gd sites differing by more than a factor of two for both compounds, the moments derived from neutron diffraction are essentially equal in Gd5Ir2Bi. This implies an unusual departure from the commonly assumed scaling between B hf G d and μGd. Neutron powder diffraction shows that Gd5Ir2Bi is a c-axis ferromagnet at 3.6 K. We find no evidence for a FM → AF transition.

  5. Valence photoelectron spectroscopy of Gd silicides

    SciTech Connect

    Braicovich, L. ); Puppin, E.; Lindau, I. ); Iandelli, A.; Olcese, G.L.; Palenzona, A. )

    1990-02-15

    Gd{sub 3}Si{sub 5}, GdSi, and Gd{sub 5}Si{sub 3} were investigated with photoemission spectroscopy in the photon-energy range 40.8--149 eV by exploiting the energy dependence of the photoemission cross sections and the valence resonance at the crossing of the Gd 4{ital d}-4{ital f} threshold. The modification of the spectra versus photon energy, along with their stoichiometry dependence, show the relevance of covalent mixed Gd 5{ital d}--Si 3{ital sp} states in the formation of the chemical bond. In the region close to the Fermi level an increase of the {ital d} contribution is observed. These points are discussed in connection with the existing models of the silicide bond.

  6. GD2-targeted immunotherapy and radioimmunotherapy

    PubMed Central

    Dobrenkov, Konstantin; Cheung, Nai-Kong

    2014-01-01

    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’s 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 antibody, cytokines, cells and genetically engineered products all directed at GD2 are rapidly moving into the clinic. In the review, past and present immunotherapy trials directed at GD2 will be summarized, highlighting the lessons learned and the future directions. PMID:25440605

  7. Synthesis, structure and magnetic properties of Fe-Gd nanocapsules coated with B 2O 3/H 3BO 3 and Fe 3BO 5+GdBO 3

    NASA Astrophysics Data System (ADS)

    Si, P. Z.; Brück, E.; Zhang, Z. D.; Tegus, O.; Buschow, K. H. J.; Zhang, W. S.; Klaasse, J. C. P.; de Boer, F. R.

    2004-11-01

    Nanocapsules consisting of B 2O 3/H 3BO 3 encapsulating Fe-Gd cores have been synthesized by an arc-discharge process using metal-boron alloys as cathode. Most of the nanocapsules have a well-constructed shell/core structure with a uniform B 2O 3/H 3BO 3 shell. Heat-treatment induces reactions between the shell and the core, resulting in the formation of a Fe 3BO 5+GdBO 3 matrix embedded with Fe nanoparticles, reduction of the metallic-core size and decrease of the blocking temperature TB. Above TB, the magnetization curves plotted vs. H/T overlap and show zero coercivity. Below TB, the coercivity shows a linear dependence when plotted vs. T1/2. However, the coercivity- T1/2 curve below 60 K has a different slope from that above 60 K, indicating the existence of two different magnetic phases in the nanocapsules. Different from bulk Fe 3BO 5, nanoscale Fe 3BO 5 particles have a lower transition temperature to the weak-ferromagnetic state, and magnetic hysteresis is absent due to size effects.

  8. Influence of the nanoparticle sizes on the photo-induced absorption of La-Ga-S-O-Dy glass nanocomposites

    NASA Astrophysics Data System (ADS)

    Lakshminarayana, G.; Rusek, K.; El-Naggar, A. M.; Albassam, A. A.; Kolcun, M.; Myronchuk, G.

    2016-07-01

    We have established that the illumination by two coherent beams originating from nanosecond Nd:YAG laser at wavelengths 1064 nm and 532 nm in the La-Ga-S-O-Gd:PVA La-Ga-S-O-Dy polymer glass nanocomposites leads to substantial changes in the absorption. The effect is completely reversible and disappears after interruption of the optical treatment. The illumination power density was varied up to 0.6 GW/cm2. All the samples show destruction less than 0.2% changes after more than 300,000 laser pulses. The beams were incident with the angles varying between 45° and 50° with respect to the nanocomposite surface. Moreover, the additional analysis of TEM did not demonstrate any additional aggregations. The role of light polarizations, beam stability, and light scattering is discussed.

  9. 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 1λ - 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.

  10. Hydrogenation behavior of the R4MgCo (R=Y, La, Nd, Tb) compounds

    NASA Astrophysics Data System (ADS)

    Shtender, V. V.; Paul-Boncour, V.; Riabov, A. B.; Denys, R. V.; Zavaliy, I. Yu.

    2015-09-01

    The hydrogen absorption properties of the R4MgCo compounds (R=Y, La, Nd, Tb; str. type Gd4RhIn; sp.gr. F 4 bar 3 m) have been studied for the first time. It was shown that their hydrogen storage capacity reaches about 2 wt%. At low pressure hydrogenation and moderately elevated temperatures the formed hydrides preserve the original structure of the metallic matrix. The crystal structure of the R4MgCoHx hydrides have been determined by XRD. Experimental hydrogen storage capacity (12 at.H/f.u. for Y4MgCo) is in good agreement with the theoretically calculated models, which allow also to estimate the distribution of H-atoms in metal lattice. TDS and DSC experiments demonstrated the multistep desorption process. XRD studies of the Tb4MgCoHx sample after TDS demonstrated the formation of TbH2 as the main phase and disproportionation of the parent compound.

  11. Forensic analysis of dyed textile fibers.

    PubMed

    Goodpaster, John V; Liszewski, Elisa A

    2009-08-01

    Textile fibers are a key form of trace evidence, and the ability to reliably associate or discriminate them is crucial for forensic scientists worldwide. While microscopic and instrumental analysis can be used to determine the composition of the fiber itself, additional specificity is gained by examining fiber color. This is particularly important when the bulk composition of the fiber is relatively uninformative, as it is with cotton, wool, or other natural fibers. Such analyses pose several problems, including extremely small sample sizes, the desire for nondestructive techniques, and the vast complexity of modern dye compositions. This review will focus on more recent methods for comparing fiber color by using chromatography, spectroscopy, and mass spectrometry. The increasing use of multivariate statistics and other data analysis techniques for the differentiation of spectra from dyed fibers will also be discussed. PMID:19543886

  12. 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.

  13. Perpendicular magnetic anisotropy of Tb magnetic moments in Tb/Fe multilayers

    NASA Astrophysics Data System (ADS)

    Trhlík, M.; De Moor, P.; Mibu, K.; Severijns, N.; Shinjo, T.; Van Geert, A.; Vanneste, L.

    1997-01-01

    The direction of the magnetic moment of Tb in Fe(40 Å)/Tb( x Å) ( x = 10 and 20) multilayers has been studied using the low-temperature nuclear orientation technique in the temperature range 5-50 mK and in the external magnetic field range Bext = 0-8.5 T, with Bext applied along the sample plane. The anisotropy of the 299 keV 160Tb γ-line was monitored in three directions with respect to Bext and the sample plane. The perpendicular magnetic anisotropy (PMA) of the Tb magnetic moments has been found at zero Bext for both systems. The PMA effect is increased when the Tb layers are thinner. An application of Bext turned the Tb magnetic moments towards the sample plane, without reaching a full alignment even at Bext = 8.5 T.

  14. Phosphor thermometry in turbulent hot gas flows applying Dy:YAG and Dy:Er:YAG particles

    NASA Astrophysics Data System (ADS)

    Jovicic, Gordana; Zigan, Lars; Will, Stefan; Leipertz, Alfred

    2015-01-01

    In order to improve the phosphorescence emission behavior of phosphor powders for temperature measurements in a gas flow, the activator concentration in Dy:YAG was varied and the phosphor was co-doped with the sensitizer erbium (Er). Phosphorescence spectra, overall phosphorescence signal intensities and the phosphorescence lifetime were characterized in a furnace up to 1400 K. Planar thermometry was conducted in hot gas flows, whereby an improved average temperature uncertainty of about 3% was obtained using Dy:YAG and of 1.8% for Dy:Er:YAG for temperatures of 450 K.

  15. Photoluminescence investigation of rare-earth activated GdCa{sub 3}(GaO){sub 3}(BO{sub 3}){sub 4} phosphors under UV excitation

    SciTech Connect

    Kyung, Hyun-Ai; Choi, Sungho; Seong, Tae-Yeon; Jung, Ha-Kyun

    2009-04-02

    A borate compound was adopted as a new host material of Eu{sup 3+} and Tb{sup 3+} activators to fabricate efficient luminescence materials. The phosphor compositions, Gd{sub 1-x}Eu{sub x}Ca{sub 3}(GaO){sub 3}(BO{sub 3}){sub 4} and Gd{sub 1-x}Tb{sub x}Ca{sub 3}(GaO){sub 3}(BO{sub 3}){sub 4}, were synthesized by conventional solid-state reactions. The crystalline phases of the resulting powders were identified using an X-ray diffraction system. Their photoluminescence properties were investigated under long-wavelength UV excitation. The Eu{sup 3+}-doped and Tb{sup 3+}-doped GdCa{sub 3}(GaO){sub 3}(BO{sub 3}){sub 4} phosphors efficiently emitted red and green light, respectively. The temperature dependency of emission intensity was measured in a range from room temperature to 150 deg. C. The emission intensities of the red and green phosphors at 150 deg. C are 87% and 91% of those at room temperature, respectively. In addition, the decay times of both the red and green phosphors are shorter than 3 ms.

  16. Magnetism in Gd-W films

    SciTech Connect

    Gadioli, Giovana Z.; Rouxinol, Francisco P.; Gelamo, Rogerio V.; Santos, Adenilson O. dos; Cardoso, Lisandro P.; Bica de Moraes, Mario A.

    2008-05-01

    Vapor condensation techniques are useful to prepare magnetic alloys whose components have low or even negligible equilibrium mutual solubility. In this work, one of these techniques--sputtering--was used to obtain Gd{sub x}W{sub 1-x} alloys whose magnetic properties were investigated as a function of the Gd atomic concentration x. Gadolinium and various Gd-based alloys are promising materials for magnetic refrigeration and this was one of the motivations for this study. The Gd{sub x}-W{sub 1-x} films were sputter deposited from Gd and W targets with x ranging from 0 to 1 as determined by x-ray energy-dispersive spectroscopic analyses. X-ray diffraction patterns indicate that crystalline structures were formed at low and high Gd concentrations, while at intermediate concentrations, the films were amorphous. Magnetization measurements, performed as a function of temperature and with static and alternating applied fields, reveal a spin glasslike behavior in all the W-containing samples for temperatures below the freezing temperature T{sub f}. For low and intermediate Gd concentrations, and for T>T{sub f}, the films were paramagnetic, while a ferromagnetic phase was observed in the Gd-W alloy of the highest Gd content. The magnetocaloric effect was investigated from the magnetization isotherms M versus H, from which the isothermal magnetic entropy variation {delta}S{sub M} as a function of T, for the removal of an applied field of 50 kOe, was determined. It was observed that the maximum value of {delta}S{sub M} for each {delta}S{sub M} versus T curve and the temperature at which these maxima occur, are strongly dependent on x.

  17. Probing the structure-relaxivity relationship of bis-hydrated Gd(DOTAla) derivatives.

    PubMed

    Boros, Eszter; Caravan, Peter

    2015-03-01

    Two structural isomers of the heptadentate chelator DO3Ala were synthesized, with carboxymethyl groups at either the 1,4- or 1,7-positions of the cyclen macrocycle. To interrogate the relaxivity under different rotatational dynamics regimes, the pendant primary amine was coupled to ibuprofen to enable binding to serum albumin. These chelators 6a and 6b form bis(aqua) ternary complexes with Gd(III) or Tb(III) as estimated from relaxivity measurements or luminescence lifetime measurements in water. The relaxivity of [Gd(6a)(H2O)2] and [Gd(6b)(H2O)2] was measured in the presence and absence of coordinating anions prevalent in vivo such as phosphate, lactate, and bicarbonate and compared with data attained for the q = 2 complex [Gd(DO3A)(H2O)2]. We found that relaxivity was reduced through formation of ternary complexes with lactate and bicarbonate, albeit to a lesser degree then the relaxivity of Gd(DO3A). In the presence of 100-fold excess phosphate, relaxivity was slightly increased and typical for q = 2 complexes of this size (8.3 mM(-1) s(-1) and 9.5 mM(-1) s(-1), respectively, at 37 C, 60 MHz). Relaxivity for the complexes in the presence of HSA corresponded well to relaxivity obtained for complexes with reduced access for inner-sphere water (13.5 and 12.7 mM(-1) s(-1) at 37 C, 60 MHz). Mean water residency time at 37 C was determined using temperature-dependent (17)O-T2 measurements at 11.7 T and calculated to be (310)?M = 23 1 ns for both structural isomers. Kinetic inertness under forcing conditions (pH 3, competing DTPA ligand) was found to be comparable to [Gd(DO3A)(H2O)]. Overall, we found that the replacement of one of the acetate arms of DO3A with an amino-propionate arm does not significantly alter the relaxometric and kinetic inertness properties of the corresponding Gd complexes; however, it does provide access to easily functionalizable q = 2 derivatives. PMID:25693053

  18. Pressure effect on ferroelectric properties of multiferroics RMn2O5, (R = Gd, Tm)

    NASA Astrophysics Data System (ADS)

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

    The pressure effect on the ferroelectric properties of the multiferroics GdMn2O5 and TmMn2O5 is studied up to 18.2 kbar. Unlike in RMn2O5 (R= Tb, Ho, Y), no significant change in polarization is observed in TmMn2O5 up to 16.6 kbar . However, a new ferroelectric phase is observed in GdMn2O5 above a critical pressure, Pc = 10 kbar at higher temperature. Our result indicates that pressure decouples the Gd moment from the Mn spin system and splits the ferroelectric phase. Thermal expansion data shows a large increase of the c axis at the ambient-pressure ferroelectric transition. The pressure-induced contraction of the c lattice parameter is found to be the cause for splitting of ferroelectric phase by decoupling of two spin systems above Pc. The pressure-temperature phase diagram is derived based on dielectric and ferroelectric properties.

  19. 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

  20. Structures and magnetic properties of several phenoxo-O bridged dinuclear lanthanide complexes: Dy derivatives displaying substituent dependent magnetic relaxation behavior.

    PubMed

    Wang, Wen-Min; Qiao, Wan-Zhen; Zhang, Hong-Xia; Wang, Shi-Yu; Nie, Yao-Yao; Chen, Hong-Man; Liu, Zhen; Gao, Hong-Ling; Cui, Jian-Zhong; Zhao, Bin

    2016-05-10

    Nine dinuclear Ln(iii) complexes, [Ln(dbm)2(L)]2 (Ln = Eu (), Tb (), Dy (), Ho (), Er ()) and [Ln(dbm)2(L')]2 (Ln = Tb (), Dy (), Ho (), Er ()) (dbm = 1,3-diphenyl-1,3-propanedione, HL = 2-[[(4-methoxy-phenyl)imino]methyl]-8-hydroxy-quinoline and HL' = 2-[[(4-ethoxyphenyl)imino]methyl]-8-hydroxyquinoline) have been synthesized, and structurally and magnetically characterized. The nine complexes are all phenoxo-O bridged binuclear complexes, in which Ln1 and Ln1a are in an eight-coordinated environment bridged by two phenoxido oxygen atoms of two 8-hydroxyquinoline Schiff base ligands. Although complexes and have very similar structures, magnetic studies reveal that they exhibit different magnetic relaxation behaviors with the effective barriers (ΔE/kB) of 34.5 K for and 67.6 K for . The dissimilar dynamic magnetic behaviors of and mostly result from the different electron-donating effect induced by the two alkoxy (-OCH3 and -OC2H5) of the 8-hydroxyquinoline Schiff base ligands. Meanwhile, for complexes , , and , there are no observed magnetic relaxation behaviors under a zero dc field. In addition, the luminescence properties of , and were studied. PMID:27095548

  1. Standards for TB care in India: A tool for universal access to TB care.

    PubMed

    Nair, Sreenivas Achuthan; Sachdeva, K S; Malik, Parmar; Chandra, S; Ramachandran, R; Kulshrestha, N; Chopra, K K; Khaparde, S D

    2015-10-01

    In 2014, Government of India in collaboration with World Health Organization Country Office for India released the policy document on Standards for tuberculosis (TB) care in India after in-depth deliberation with national and international experts. The standards for TB care represent what is expected for quality TB care from the Indian healthcare system including both public and private systems. The details of each standard have been compiled in this review article. It is envisioned that the standards detailed in the manuscript are adapted by all TB care providers across the country. PMID:26970459

  2. Multidrug-Resistant Tuberculosis (MDR TB)

    MedlinePlus

    ... prisons, or homeless shelters. If you work in hospitals or health-care settings where TB patients are likely to be seen, you should consult infection control or occupational health experts. Ask about administrative and ...

  3. Extensively Drug-Resistant Tuberculosis (XDR TB)

    MedlinePlus

    ... Epidemiology of Tuberculosis in Correctional Facilities, United States, 1993-2014 Prevention and Control of Tuberculosis in Correctional ... cases of XDR TB have been reported between 1993 and 2011*. *The National Tuberculosis Surveillance System (NTSS) ...

  4. TB in Children in the United States

    MedlinePlus

    ... for the Diagnosis of TB Background General Considerations Research Needs Molecular Drug Susceptibility Tests (DSTs) Communication Plan for New ... Possible Scenarios and Scope of Testing for a Molecular DR Testing Service Research Needs General Recommendations of the Expert Panel Communication ...

  5. 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

  6. HIV/STD/TB PREVENTION NEWS DATABASE

    EPA Science Inventory

    The CDC National Prevention Information Network (NPIN) is the U.S. reference, referral, and distribution service for information on HIV/AIDS, sexually transmitted diseases (STDs), and tuberculosis (TB). NPIN produces, collects, catalogs, processes, stocks, and disseminates materi...

  7. 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 λ|| and linear anisotropic λa (=λ|| - λ⊥) 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 λ111, 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.

  8. Determination of the cross section for (n,p) reaction with producing short-lived nuclei on the 162,163Dy isotopes at 13.5 and 14.8 MeV

    NASA Astrophysics Data System (ADS)

    Luo, Junhua; Feng, Zhifu; An, Li; Jiang, Li; He, Long

    2016-06-01

    Activation cross-sections for the 162Dy(n,p)162Tb and 163Dy(n,p)163Tb reactions have been measured by means of the activation technique and a coaxial HPGe γ-ray detector at 13.5 and 14.8 MeV. The fast neutrons were produced via the 3H(d,n)4He reaction on Pd-300 neutron generator. The natural high-purity Dy2O3 powder was used as target material. Theoretical excitation functions were calculated using the nuclear-reaction codes EMPIRE-3.2 Malta and TALYS-1.6 with default parameters, at neutron energies varying from the reaction threshold to 20 MeV. The results were also discussed and compared with some corresponding values found in the literature, with the comprehensive evaluation data in ENDF/B-VII.1 and JENDF-4.0 libraries, and with the estimates obtained from a published empirical formula based on the statistical model with Q-value dependence and odd-even effects taken into consideration.

  9. Bortezomib Does Not Reduce Muscular Dystrophy in the dy2J/dy2J Mouse Model of Laminin α2 Chain-Deficient Muscular Dystrophy

    PubMed Central

    Körner, Zandra; Durbeej, Madeleine

    2016-01-01

    Congenital muscular dystrophy with laminin α2 chain-deficiency, also known as MDC1A, is a severe neuromuscular disorder for which there is no cure. Patients with complete laminin α2 chain-deficiency typically have an early onset disease with a more severe muscle phenotype while patients with residual laminin α2 chain expression usually have a milder disease course. Similar genotype-phenotype correlations can be seen in the dy3K/dy3K and dy2J/dy2J mouse models of MDC1A, respectively, with dy3K/dy3K mice presenting the more severe phenotype. Recently, we demonstrated that the proteasome inhibitor bortezomib partially improves muscle morphology and increases lifespan in dy3K/dy3K mice. Here, we explore the use of bortezomib in dy2J/dy2J animals. However, bortezomib neither improved histological hallmarks of disease nor increased muscle strength and locomotive activity in dy2J/dy2J mice. Altogether our data suggest that proteasome inhibition does not mitigate muscle dysfunction caused by partial laminin α2 chain-deficiency. Still, it is possible that proteasome inhibition could be useful as a supportive therapy in patients with complete absence of laminin α2 chain. PMID:26731667

  10. β-decay half-lives of new neutron-rich rare-earth isotopes 159Pm,162Sm, and 166Gd

    NASA Astrophysics Data System (ADS)

    Ichikawa, S.; Asai, M.; Tsukada, K.; Haba, H.; Nagame, Y.; Shibata, M.; Sakama, M.; Kojima, Y.

    2005-06-01

    The new neutron-rich rare-earth isotopes 159Pm, 162Sm, and 166Gd produced in the proton-induced fission of 238U were identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport system. The half-lives of 159Pm, 162Sm, and 166Gd were determined to be 1.5 ± 0.2, 2.4 ± 0.5, and 4.8 ± 1.0 s respectively. The partial decay scheme of 166Gd was constructed from γγ-coincidence data. A more accurate half-life value of 25.6 ± 2.2 s was obtained for the previously identified isotope 166Tb. The half-lives measured in the present study are in good agreement with the theoretical predictions calculated by the second generation of the gross theory with the atomic masses evaluated by Audi and Wapstra.

  11. Temperature Sensing Above 1000 C Using Cr-Doped GdAlO3 Spin-Allowed Broadband Luminescence

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I.; Chambers, Matthew D.

    2012-01-01

    Cr-doped GdAlO3 (Cr:GdAlO3) is shown to produce remarkably high-intensity spin-allowed broadband luminescence with sufficiently long decay times to make effective luminescence-decay-time based temperature measurements above 1000 C. This phosphor is therefore an attractive alternative to the much lower luminescence intensity rare-earth-doped thermographic phosphors that are typically utilized at these elevated temperatures. In particular, Cr:GdAlO3 will be preferred over rare-earth-doped phosphors, such as Dy:YAG, at temperatures up to 1200 C for intensity-starved situations when the much lower emission intensity from rare-earth-doped phosphors is insufficient for accurate temperature measurements in the presence of significant radiation background. While transition-metal-doped phosphors such as Cr:Al2O3 (ruby) are known to exhibit high luminescence intensity at low dopant concentrations, quenching due to nonradiative decay pathways competing with the (sup 2)E to (sup 4)A(sub 2) radiative transition (R line) has typically restricted their use for temperature sensing to below 600 C. Thermal quenching of the broadband (sup 4)T(sub 2) to (sup 4)A(sub 2) radiative transition from Cr:GdAlO3, however, is delayed until much higher temperatures (above 1000 C). This spin-allowed broadband emission persists to high temperatures because the lower-lying (sup 2)E energy level acts as a reservoir to thermally populate the higher shorter-lived (sup 4)T(sub 2) energy level and because the activation energy for nonradiative crossover relaxation from the (sup 4)T(sub 2) level to the (sup 4)A(sub 2) ground state is high. The strong crystal field associated with the tight bonding of the AlO6 octahedra in the GdAlO3 perovskite structure is responsible for this behavior.

  12. The performance and limitation of T-SPOT.TB for the diagnosis of TB in a high prevalence setting

    PubMed Central

    Liu, Zhonghua; Li, Zhiqiang

    2014-01-01

    Background Tuberculosis (TB) diagnosis remains difficulty. The previous reports have shown that the T-SPOT.TB assay may be a more promising diagnostic tool for TB, however, it needs a further study to evaluate the diagnostic value of T-SPOT.TB for the specific populations in a high prevalence setting. Methods In this present study, we conducted stratified and comparable analyses to explore the clinical value and the limitation of T-SPOT.TB assay in TB diagnosis in a high TB prevalence setting, Southern China. A total of 413 subjects including 163 pulmonary TB (PTB), 39 extrapulmonary TB (EPTB), 106 non-TB pulmonary diseases (NTBPDs), 20 medical staff and 85 healthy controls were included in the study. Results According to T-SPOT.TB, there had a high incidence of latent TB infection (LTBI) in general population in Southern China, especially in the NTBPDS and medical staff. The T-SPOT.TB had a high performance in the diagnosis of active TB (ATB) in a lower risk of TB infection population such as the general population, however, the T-SPOT.TB for the diagnosis of ATB in the high risk of TB infection populations involving close contacts such as the patients with pulmonary diseases (PD) or medical staff isn’t reliable due to the interference by LTBI. Under this condition, the value of rule-out of the assay was seemed to be better than that of rule-in. We believed that the T-SPOT.TB is suitable for screening both the EPTB and the ATB combined with diabetes mellitus (DM). However, we found that the sensitivity of T-SPOT.TB in sputum smear-negative population wasn’t as high as that in smear-positive population. Conclusions The T-SPOT.TB testing results should be interpreted with caution combined with subject’s characteristics in a high prevalence setting. PMID:24976994

  13. Giant electrostriction in Gd-doped ceria.

    PubMed

    Korobko, Roman; Patlolla, Anitha; Kossoy, Anna; Wachtel, Ellen; Tuller, Harry L; Frenkel, Anatoly I; Lubomirsky, Igor

    2012-11-14

    Gd-doped CeO(2) exhibits an anomalously large electrostriction effect generating stress that can reach 500 MPa. In situ XANES measurements indicate that the stress develops in response to the rearrangement of cerium-oxygen vacancy pairs. This mechanism is fundamentally different from that of materials currently in use and suggests that Gd-doped ceria is a representative of a new family of high-performance electromechanical materials. PMID:22933377

  14. Dy0.64{Dy5[Fe2C9]}: A complex carbide with a composite structure

    NASA Astrophysics Data System (ADS)

    Davaasuren, Bambar; Dashjav, Enkhtsetseg; Kniep, Rüdiger; Kreiner, Guido; Schnelle, Walter; Akselrud, Lev; Smaalen, Sander van; Wölfel, Alexander

    2012-06-01

    The ternary carbide Dy5.64[Fe2C9] has been prepared by high temperature synthesis from the elements. The compound forms as a composite structure with two partial structures, {Dy5[Fe2C9]} and {Dy0.64} crystallizing in space groups Pnam and Pbam, respectively. The lattice parameters a=2934.63(9) pm and b=1263.63(5) pm for the two partial structures are identical, whereas the c lattice parameters for {Dy5[Fe2C9]} (cH=504.14(3) pm) and {Dy0.64} (cG=1056.01(5) pm) are different. This gives rise to a modulated structure in the (3+1)D superspace group Pnam(00g) with q=cH/cG=0.4775. The refinement converged to R(F) values below 0.055 for each partial structure using harmonic and Crenel functions. The compound is a bad metallic conductor and represents a new structure type composed of Dy3+ species embedded in a matrix of discrete planar FeC(C2)2 units and edge-sharing Fe(C2)4 tetrahedra forming infinite chains Fe(C2)4/2 running along the c axis.

  15. GAPS IN THE GD-1 STAR STREAM

    SciTech Connect

    Carlberg, R. G.; Grillmair, C. J. E-mail: carl@ipac.caltech.edu

    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.

  16. Dilution effects in spin 7/2 systems. The case of the antiferromagnet GdRhIn5

    NASA Astrophysics Data System (ADS)

    Lora-Serrano, R.; Garcia, D. J.; Betancourth, D.; Amaral, R. P.; Camilo, N. S.; Estévez-Rams, E.; Ortellado G. Z., L. A.; Pagliuso, P. G.

    2016-05-01

    We report the structural and magnetic characterization of La-substituted Gd1-x Lax RhIn5(x ≤ 0.50) antiferromagnetic (AFM) compounds. The magnetic responses of pure GdRhIn5 are well described by a S=7/2 Heisenberg model. When Gd3+ ions are substituted by La3+, the maximum of the susceptibility and the inflection point of the magnetic specific heat are systematically shifted to lower temperatures accompanied by a broadening of the transition. The data is qualitatively explained by a phenomenological model which incorporates a distribution of magnetic regions with different transition temperatures (TN). The universal behaviour of the low temperature specific heat is found for La (vacancies) concentrations below x=0.40 which is consistent with spin wave excitations. For x=0.5 this universal behaviour is lost. The sharp second order transition of GdRhIn5 is destroyed, as seen in the specific heat data, contrary to what is expected for a Heisenberg model. The results are discussed in the context of the magnetic behaviour observed for the La-substituted (Ce,Tb,Nd)RhIn5 compounds.

  17. Transition Probabilities of Gd I

    NASA Astrophysics Data System (ADS)

    Bilty, Katherine; Lawler, J. E.; Den Hartog, E. A.

    2011-01-01

    Rare earth transition probabilities are needed within the astrophysics community to determine rare earth abundances in stellar photospheres. The current work is part an on-going study of rare earth element neutrals. Transition probabilities are determined by combining radiative lifetimes measured using time-resolved laser-induced fluorescence on a slow atom beam with branching fractions measured from high resolution Fourier transform spectra. Neutral rare earth transition probabilities will be helpful in improving abundances in cool stars in which a significant fraction of rare earths are neutral. Transition probabilities are also needed for research and development in the lighting industry. Rare earths have rich spectra containing 100's to 1000's of transitions throughout the visible and near UV. This makes rare earths valuable additives in Metal Halide - High Intensity Discharge (MH-HID) lamps, giving them a pleasing white light with good color rendering. This poster presents the work done on neutral gadolinium. We will report radiative lifetimes for 135 levels and transition probabilities for upwards of 1500 lines of Gd I. The lifetimes are reported to ±5% and the transition probabilities range from 5% for strong lines to 25% for weak lines. This work is supported by the National Science Foundation under grant CTS 0613277 and the National Science Foundation's REU program through NSF Award AST-1004881.

  18. Glycolipid GD3 and GD3 synthase are key drivers for glioblastoma stem cells and tumorigenicity.

    PubMed

    Yeh, Shih-Chi; Wang, Pao-Yuan; Lou, Yi-Wei; Khoo, Kay-Hooi; Hsiao, Michael; Hsu, Tsui-Ling; Wong, Chi-Huey

    2016-05-17

    The cancer stem cells (CSCs) of glioblastoma multiforme (GBM), a grade IV astrocytoma, have been enriched by the expressed marker CD133. However, recent studies have shown that CD133(-) cells also possess tumor-initiating potential. By analysis of gangliosides on various cells, we show that ganglioside D3 (GD3) is overexpressed on eight neurospheres and tumor cells; in combination with CD133, the sorted cells exhibit a higher expression of stemness genes and self-renewal potential; and as few as six cells will form neurospheres and 20-30 cells will grow tumor in mice. Furthermore, GD3 synthase (GD3S) is increased in neurospheres and human GBM tissues, but not in normal brain tissues, and suppression of GD3S results in decreased GBM stem cell (GSC)-associated properties. In addition, a GD3 antibody is shown to induce complement-dependent cytotoxicity against cells expressing GD3 and inhibition of GBM tumor growth in vivo. Our results demonstrate that GD3 and GD3S are highly expressed in GSCs, play a key role in glioblastoma tumorigenicity, and are potential therapeutic targets against GBM. PMID:27143722

  19. Recent tuberculosis diagnosis toward the end TB strategy.

    PubMed

    Cheon, Seon Ah; Cho, Hyun Hee; Kim, Jeonghyo; Lee, Jaebeom; Kim, Hwa-Jung; Park, Tae Jung

    2016-04-01

    Tuberculosis (TB) is an infectious bacterial disease caused by Mycobacterium tuberculosis. Despite global TB eradication efforts, it is still a global public health concern, especially in low- and middle-income countries. Most of the active TB infections are curable with early diagnosis and appropriate treatment, but drug-resistant TB is difficult and expensive to treat in immunocompetent as well as immunocompromised individuals. Thus, rapid, economic, and accurate point-of care tools for TB diagnosis are required urgently. This review describes the history of M. tuberculosis detection methods up to date and the recent advances using nanotechnology for point-of-care testing of TB diagnosis. PMID:26853124

  20. Cell Death and Autophagy in TB

    PubMed Central

    Moraco, Andrew H.; Kornfeld, Hardy

    2014-01-01

    Mycobacterium tuberculosis has succeeded in infecting one third of the human race though inhibition or evasion of innate and adaptive immunity. The pathogen is a facultative intracellular parasite that uses the niche provided by mononuclear phagocytes for its advantage. Complex interactions determine whether the bacillus will or will not be delivered to acidified lysosomes, whether the host phagocyte will survive infection or die, and whether the timing and mode of cell death works to the advantage of the host or the pathogen. Here we discuss cell death and autophagy in TB. These fundamental processes of cell biology feature in all aspects of TB pathogenesis and may be exploited to the treatment or prevention of TB disease. PMID:25453227

  1. The isothermal section of Gd-Ni-Si system at 1070 K

    NASA Astrophysics Data System (ADS)

    Morozkin, A. V.; Knotko, A. V.; Yapaskurt, V. O.; Manfrinetti, P.; Pani, M.; Provino, A.; Nirmala, R.; Quezado, S.; Malik, S. K.

    2016-03-01

    The Gd-Ni-Si system has been investigated at 1070 K by X-ray and microprobe analyses. The existence of the known compounds, i.e.: GdNi10Si2, GdNi8Si3, GdNi5Si3, GdNi7Si6, GdNi6Si6, GdNi4Si, GdNi2Si2, GdNiSi3, Gd3Ni6Si2, GdNiSi, GdNiSi2, GdNi0.4Si1.6, Gd2Ni2.35Si0.65, Gd3NiSi2, Gd3NiSi3 and Gd6Ni1.67Si3, has been confirmed. Moreover, five new phases have been identified in this system. The crystal structure for four of them has been determined: Gd2Ni16-12.8Si1-4.2 (Th2Zn17-type), GdNi6.6Si6 (GdNi7Si6-type), Gd3Ni8Si (Y3Co8Si-type) and Gd3Ni11.5Si4.2(Gd3Ru4Ga12-type). The compound with composition ~Gd2Ni4Si3 still remains with unknown structure. Quasi-binary phases, solid solutions, were detected at 1070 K to be formed by the binaries GdNi5, GdNi3, GdNi2, GdNi, GdSi2 and GdSi1.67; while no appreciable solubility was observed for the other binary compounds of the Gd-Ni-Si system. Magnetic properties of the GdNi6Si6, GdNi6.6Si6 and Gd3Ni11.5Si4.2 compounds have also been investigated and are here reported.

  2. Gd(III)-nanodiamond conjugates for MRI contrast enhancement

    PubMed Central

    Manus, Lisa M.; Mastarone, Daniel J.; Waters, Emily A.; Zhang, Xue-Qing; Schultz-Sikma, Elise A.; MacRenaris, Keith W.; Ho, Dean

    2010-01-01

    A Gd(III)-nanodiamond conjugate [Gd(III)-ND] was prepared and characterized, enabling detection of nanodiamonds by MR imaging. The Gd(III)-ND particles significantly reduced the T1 of water protons with a per-Gd(III) relaxivity of 58.82 ± 1.18 mM−1s−1 at 1.5 Tesla (60 MHz). This represents a tenfold increase compared to the monomer Gd(III) complex (r1 = 5.42 ± 0.20 mM−1s−1) and is among the highest per-Gd(III) relaxivities reported. PMID:20038088

  3. The campaign against TB: governments must commit themselves. TB in Africa.

    PubMed

    Chaulet, P

    1996-01-01

    This article presents an interview with Pierre Chaulet on the campaign against tuberculosis (TB) in Africa. Chaulet noted during the 9th IUATLD Conference of the Africa Region that the national TB control programs have taken on a new commitment in Africa since the declaration of TB as a global emergency in the 1990s. The TB control program package consists of five principal components: 1) political will of the government and its commitment to support the program; 2) case detection; 3) initiation of short course chemotherapy among detected cases; 4) ensuring the regular supply of essential anti-TB drugs; and 5) establishing a registry and reporting system for program monitoring and evaluation. Of the 40 African countries participating in the conference, 30 have efficient programs. Comparing the management of National TB Control Programs in Francophone and Anglophone Africa, it is noted that both are complementary, although generally, public health issues are more easily integrated into the medical training in the Anglophone countries than they are in the Francophone. Anglophone uses a more comprehensive approach to public health while countries in the Francophone practiced a more traditional university centralization. Finally, Chaulet gives his comment on the role of WHO in addressing concerns over the financial issues involved in TB Control Programs, particularly in the mobilization of resources from nongovernmental organizations and international institutions. PMID:12179805

  4. Combination of Cytokine Responses Indicative of Latent TB and Active TB in Malawian Adults

    PubMed Central

    Hur, Yun-Gyoung; Gorak-Stolinska, Patricia; Ben-Smith, Anne; Lalor, Maeve K.; Chaguluka, Steven; Dacombe, Russell; Doherty, T. Mark; Ottenhoff, Tom H.; Dockrell, Hazel M.; Crampin, Amelia C.

    2013-01-01

    Background An IFN-γ response to M. tuberculosis-specific antigens is an effective biomarker for M. tuberculosis infection but it cannot discriminate between latent TB infection and active TB disease. Combining a number of cytokine/chemokine responses to M. tuberculosis antigens may enable differentiation of latent TB from active disease. Methods Asymptomatic recently-exposed individuals (spouses of TB patients) were recruited and tuberculin skin tested, bled and followed-up for two years. Culture supernatants, from a six-day culture of diluted whole blood samples stimulated with M. tuberculosis-derived PPD or ESAT-6, were measured for IFN-γ, IL-10, IL-13, IL-17, TNF-α and CXCL10 using cytokine ELISAs. In addition, 15 patients with sputum smear-positive pulmonary TB were recruited and tested. Results Spouses with positive IFN-γ responses to M. tuberculosis ESAT-6 (>62.5 pg/mL) and TB patients showed high production of IL-17, CXCL10 and TNF-α. Higher production of IL-10 and IL-17 in response to ESAT-6 was observed in the spouses compared with TB patients while the ratios of IFN-γ/IL-10 and IFN-γ/IL-17 in response to M. tuberculosis-derived PPD were significantly higher in TB patients compared with the spouses. Tuberculin skin test results did not correlate with cytokine responses. Conclusions CXCL10 and TNF-α may be used as adjunct markers alongside an IFN-γ release assay to diagnose M. tuberculosis infection, and IL-17 and IL-10 production may differentiate individuals with LTBI from active TB. PMID:24260295

  5. Investigations of the effect of nonmagnetic Ca substitution for magnetic Dy on spin-freezing in Dy2Ti2O7

    NASA Astrophysics Data System (ADS)

    Anand, V. K.; Tennant, D. A.; Lake, B.

    2015-11-01

    Physical properties of partially Ca substituted hole-doped Dy2Ti2O7 have been investigated by ac magnetic susceptibility {χ\\text{ac}}(T) , dc magnetic susceptibility χ (T) , isothermal magnetization M(H) and heat capacity {{C}\\text{p}}(T) measurements on Dy1.8Ca0.2Ti2O7. The spin-ice system Dy2Ti2O7 exhibits a spin-glass type freezing behavior near 16 K. Our frequency dependent {χ\\text{ac}}(T) data of Dy1.8Ca0.2Ti2O7 show that the spin-freezing behavior is significantly influenced by Ca substitution. The effect of partial nonmagnetic Ca2+ substitution for magnetic Dy3+ is similar to the previous study on nonmagnetic isovalent Y3+ substituted Dy2-x Y x Ti2O7 (for low levels of dilution), however the suppression of spin-freezing behavior is substantially stronger for Ca than Y. The Cole-Cole plot analysis reveals semicircular character and a single relaxation mode in Dy1.8Ca0.2Ti2O7 as for Dy2Ti2O7. No noticeable change in the insulating behavior of Dy2Ti2O7 results from the holes produced by 10% Ca2+ substitution for Dy3+ ions.

  6. 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

  7. A comparative study of magnetic behaviors in TbNi{sub 2}, TbMn{sub 2} and TbNi{sub 2}Mn

    SciTech Connect

    Wang, J. L.; Md Din, M. F.; Hong, F.; Cheng, Z. X.; Dou, S. X.; Kennedy, S. J.; Studer, A. J.; Campbell, S. J.; Wu, G. H.

    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.

  8. The variation in γ-ray multiplicity with nuclear temperature studied in 160Dy

    NASA Astrophysics Data System (ADS)

    Rekstad, J.; Henriquez, A.; Ingebretsen, F.; Midttun, G.; Skaali, B.; Øyan, R.; Haugland, R.; Messelt, S.; Thorsteinsen, T. F.; Løvhøiden, G.; Ekström, L. P.

    1982-11-01

    A novel method of obtaining detailed infromation on the level density far above the yrast line is described. The γ-ray multiplicity as a function of excitation energy in 160Dy is studied by means of the 161Dy(3He, α)160Dy reaction.

  9. 26 CFR 48.6715-1 - Penalty for misuse of dyed fuel.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 16 2010-04-01 2010-04-01 true Penalty for misuse of dyed fuel. 48.6715-1... of Special Application to Retailers and Manufacturers Taxes § 48.6715-1 Penalty for misuse of dyed... of any dye or marking done pursuant to § 48.4082-1 in any dyed fuel, then section 6715(a)(3)...

  10. 26 CFR 48.6715-1 - Penalty for misuse of dyed fuel.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 16 2011-04-01 2011-04-01 false Penalty for misuse of dyed fuel. 48.6715-1... of Special Application to Retailers and Manufacturers Taxes § 48.6715-1 Penalty for misuse of dyed... of any dye or marking done pursuant to § 48.4082-1 in any dyed fuel, then section 6715(a)(3)...

  11. 26 CFR 48.6715-1 - Penalty for misuse of dyed fuel.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 26 Internal Revenue 16 2013-04-01 2013-04-01 false Penalty for misuse of dyed fuel. 48.6715-1... of Special Application to Retailers and Manufacturers Taxes § 48.6715-1 Penalty for misuse of dyed... of any dye or marking done pursuant to § 48.4082-1 in any dyed fuel, then section 6715(a)(3)...

  12. 26 CFR 48.6715-1 - Penalty for misuse of dyed fuel.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 16 2012-04-01 2012-04-01 false Penalty for misuse of dyed fuel. 48.6715-1... of Special Application to Retailers and Manufacturers Taxes § 48.6715-1 Penalty for misuse of dyed... of any dye or marking done pursuant to § 48.4082-1 in any dyed fuel, then section 6715(a)(3)...

  13. Extensively drug resistant tuberculosis (XDR-TB): A potential threat.

    PubMed

    Marwar, Anaga; Shaker, Ivvala Anand; Palawan, Hemraz; Nanadal; Ranjith, M S; GokulShankar

    2010-12-01

    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

  14. Tuberculosis: Learn the Signs and Symptoms of TB Disease

    MedlinePlus

    ... Stages & Populations Travelers' Health Workplace Safety & Health Features Media Sign up for Features Get Email Updates To ... TB Personal Stories State TB Control Offices Features Media Sign up for Features Get Email Updates To ...

  15. 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 HIVTB 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

  16. One health/veterinary links associated with TB vaccines

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Objectives: participants will understand the current status of veterinary tuberculosis (TB) vaccine research for cattle and wildlife and their potential applications for development of human TB vaccines. Vaccines are lacking for many chronic intracellular pathogens requiring cell-mediated immunity ...

  17. Tuberculosis: The Connection between TB and HIV (the AIDS Virus)

    MedlinePlus

    ... Task Force Tuberculosis: The Connection between TB and HIV (the AIDS virus) Language: English Español (Spanish) Recommend ... important to know if I have TB and HIV infections? If you have HIV, it is important ...

  18. 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.

  19. High-spin states in 149Gd

    NASA Astrophysics Data System (ADS)

    Flibotte, S.; Haas, B.; Banville, F.; Gascon, J.; Taras, P.; Andrews, H. R.; Radford, D. C.; Ward, D.; Waddington, J. C.

    1991-07-01

    High-spin states in 149Gd have been investigated via the 124Sn(30Si, 5n)149Gd reaction at a beam energy of 150 MeV. Measurements of γγ-coincidences and angular distributions with respect to the nuclear spin axis allowed the decay scheme to be extended up to J≈{85}/{2}h̵and E∗ ≈ 16 MeV. Single-particle configurations were assigned to many high-spin levels based on calculations performed with the deformed Woods-Saxon potential.

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

    NASA Astrophysics Data System (ADS)

    Topsakal, M.; Wentzcovitch, R. M.

    2014-12-01

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

  1. Intracluster interactions in butterfly {Fe3LnO2} molecules with the non-Kramers ions Tb(III) and Ho(III)

    NASA Astrophysics Data System (ADS)

    Badía-Romano, L.; Rubín, J.; Bartolomé, F.; Bartolomé, J.; Luzón, J.; Prodius, D.; Turta, C.; Mereacre, V.; Wilhelm, F.; Rogalev, A.

    2015-08-01

    The intracluster exchange interactions within the "butterfly" [Fe3Ln (μ3-O )2(CCl3COO )8(H2O )(THF )3] molecules, where Ln(III) represents a lanthanide cation, have been determined by a combination of x-ray magnetic circular dichroism (XMCD) and vibrating sample magnetometry (VSM) along with an interaction model. We have studied the compounds with Ln =Tb and Ho, both non-Kramers lanthanides and with high uniaxial anisotropy, and Ln =Lu (III) and Y(III) as pseudolanthanides, which supply nonmagnetic Ln reference cases. At low temperature, the three Fe atoms can be considered as a self-unit with total spin SFe 3=5 /2 . Using the element selectivity of the XMCD magnetometry, measured at the Ln L2 ,3 edges, together with the VSM measurements, the local magnetization of the Ln ion and the Fe3 subcluster, as a function of the field and low temperature (T ≈2.5 K ), has been determined separately. These results are described quantitatively in the framework of a theoretical model based on an effective spin Hamiltonian, which considers the competing effects of intracluster interactions and the external applied magnetic field. The Ln -Fe3 exchange interaction within the {Fe3LnO2} cluster has been determined to be antiferromagnetic, in both Tb and Ho compounds, with JFeTb/kB=-0.13 (1 ) K and JFeHo/kB=-0.18 (1 ) K , respectively. In both cases, a field-induced reorientation of the Fe3 and Ln spins from antiparallel to parallel orientation takes place at a threshold field μ0H =1.1 and 2 T, for the {Fe3TbO2} and {Fe3HoO2} compounds, respectively. By comparison with other compounds of the series with uniaxial anisotropy, it is concluded that the polarizability of the Fe3 subcluster magnetic moment decreases in the trend {Fe3YO2}→{Fe3TbO2}→{Fe3HoO2}→{Fe3DyO2} , because of the increasing opposition of the exchange antiferromagnetic field caused by the Ln ion. In the Ln =Tb , Ho, and Dy, the magnetization of the whole molecule is dominated by the anisotropy of the Ln ion. The intracluster Fe3-Ln exchange interactions are very weak compared to the Ln ligand field and Fe-Fe exchange interactions.

  2. TB drug development: immunology at the table

    PubMed Central

    Nathan, Carl; Barry, Clifton E.

    2014-01-01

    Summary Our understanding of the host-pathogen relationship in tuberculosis can help guide tuberculosis (TB) 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

  3. 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.; Department of Physics, Acharya Institute of Technology, Bangalore 560090 ; Sunitha, D.V.; Dhananjaya, N.; Nagabhushana, H.; Sharma, S.C.; Nagabhushana, B.M.; Shivakumara, C.; Chakradhar, R.P.S.

    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 (15 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.

  4. 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

  5. Resonant photoemission in f electron systems: Pu and Gd

    SciTech Connect

    Tobin, J.G.; Chung, B.W.; Waddill, G.D.; Schulze, R.K.; Terry,J.; Farr, J.D.; Zocco, T.; Shuh, D.K.; Heinzelman, K.; Rotenberg, E.; Vander Laan, G.

    2003-10-14

    Resonant photoemission in the Pu 5f and Pu 6p states is compared to that in the Gd 4f and Gd 5p states. Spectral simulations, based upon an atomic model with angular momentum coupling, are compared to the Gd and Pu results. Additional spectroscopic measurements of Pu, including core level photoemission and x-ray absorption, are also presented.

  6. Resonant Photoemission in f Electron Systems: Pu& Gd

    SciTech Connect

    Tobin, J G; Chung, B W; Schulze, R K; Terry, J; Farr, J D; Shuh, D K; Heinzelman, K; Rotenberg, E; Waddill, G D; van der Laan, G

    2003-03-07

    Resonant photoemission in the Pu5f and Pu6p states is compared to that in the Gd4f and Gd5p states. Spectral simulations, based upon and atomic model with angular momentum coupling, are compared to the Gd and Pu results. Additional spectroscopic measurements of Pu, including core level photoemission and x-ray absorption are also presented.

  7. To conquer TB, patients must take their medicine.

    PubMed

    1994-07-15

    Although the US Centers for Disease Control (CDC) should report that the total number of tuberculosis (TB) cases has dropped 5.1% since 1992, experts stress that the potentially fatal lung disease is not yet under control. The incidence of drug-resistant TB remained about 13.7% of all reported TB cases in 1991 and 1992. TB is most commonly treated through the administration of four drugs given three times per week over a six-month period. TB experts and treatment specialists at the CDC and the American Thoracic Society jointly issued new treatment guidelines stressing the importance of ensuring that patients take all of their prescribed medications, even if it means going into the community and watching them swallow their pills. Patients who fail to adhere strictly to their treatment regimen of drugs risk developing drug-resistant TB disease and present a contagious public health threat. In addition to the acute risk of mortality from such resistant disease, the treatment cost of up to $150,000 dwarfs the $1,500-3,000 total expense required to treat patients with non-resistant TB under the new community based treatment program, Directly Observed Therapy (DOT). In DOT, health workers visit patients with TB in the workplace, home, and community to monitor their timely ingestion of prescribed medication against TB. Some patients have reported preference for this approach since it removes any personal worry that they may forget to comply with treatment on a regular basis. The experts also recommend that HIV-seropositive people with TB receive standard TB therapy and suggest treating TB positive parents with preventive drug therapy to control TB in children even if the children test negative for TB. The World Health Organization predicts that more than one third of the eight million new cases of TB this year will occur in people with AIDS. PMID:12179176

  8. Rare-earth chromium gallides RE{sub 4}CrGa{sub 12} (RE=Tb-Tm)

    SciTech Connect

    Slater, Brianna R.; Bie, Haiying; Stoyko, Stanislav S.; Bauer, Eric D.; Thompson, Joe D.; Mar, Arthur

    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.

  9. A world of cities and the end of TB

    PubMed Central

    Prasad, Amit; Ross, Alex; Rosenberg, Paul; Dye, Christopher

    2016-01-01

    The WHO's End TB Strategy aims to reduce TB deaths by 95% and incidence by 90% between 2015 and 2035. As the world rapidly urbanizes, more people could have access to better infrastructure and services to help combat poverty and infectious diseases, including TB. And yet large numbers of people now live in overcrowded slums, with poor access to urban health services, amplifying the burden of TB. An alignment of the Sustainable Development Goals (SDGs) for health and for urban development provides an opportunity to accelerate the overall decline in infection and disease, and to create cities free of TB. PMID:26884491

  10. A world of cities and the end of TB.

    PubMed

    Prasad, Amit; Ross, Alex; Rosenberg, Paul; Dye, Christopher

    2016-03-01

    The WHO's End TB Strategy aims to reduce TB deaths by 95% and incidence by 90% between 2015 and 2035. As the world rapidly urbanizes, more people could have access to better infrastructure and services to help combat poverty and infectious diseases, including TB. And yet large numbers of people now live in overcrowded slums, with poor access to urban health services, amplifying the burden of TB. An alignment of the Sustainable Development Goals (SDGs) for health and for urban development provides an opportunity to accelerate the overall decline in infection and disease, and to create cities free of TB. PMID:26884491

  11. Using polyvinyl chloride dyed with bromocresol purple in radiation dosimetry.

    PubMed

    Kattan, Munzer; al Kassiri, Haroun; Daher, Yarob

    2011-02-01

    Polyvinyl chloride (PVC) dyed with bromocresol purple was investigated as a high-dose radiation dosimeter. The absorbance at 417 nm depends linearly on the dose below 50 kGy. The response depends neither on dose rate nor on the irradiation temperature. The effects of post-irradiation storage in the dark and in indirect sunlight are also discussed. PMID:21109445

  12. 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.).

  13. TIME Impact - a new user-friendly tuberculosis (TB) model to inform TB policy decisions.

    PubMed

    Houben, R M G J; Lalli, M; Sumner, T; Hamilton, M; Pedrazzoli, D; Bonsu, F; Hippner, P; Pillay, Y; Kimerling, M; Ahmedov, S; Pretorius, C; White, R G

    2016-01-01

    Tuberculosis (TB) is the leading cause of death from infectious disease worldwide, predominantly affecting low- and middle-income countries (LMICs), where resources are limited. As such, countries need to be able to choose the most efficient interventions for their respective setting. Mathematical models can be valuable tools to inform rational policy decisions and improve resource allocation, but are often unavailable or inaccessible for LMICs, particularly in TB. We developed TIME Impact, a user-friendly TB model that enables local capacity building and strengthens country-specific policy discussions to inform support funding applications at the (sub-)national level (e.g. Ministry of Finance) or to international donors (e.g. the Global Fund to Fight AIDS, Tuberculosis and Malaria).TIME Impact is an epidemiological transmission model nested in TIME, a set of TB modelling tools available for free download within the widely-used Spectrum software. The TIME Impact model reflects key aspects of the natural history of TB, with additional structure for HIV/ART, drug resistance, treatment history and age. TIME Impact enables national TB programmes (NTPs) and other TB policymakers to better understand their own TB epidemic, plan their response, apply for funding and evaluate the implementation of the response.The explicit aim of TIME Impact's user-friendly interface is to enable training of local and international TB experts towards independent use. During application of TIME Impact, close involvement of the NTPs and other local partners also builds critical understanding of the modelling methods, assumptions and limitations inherent to modelling. This is essential to generate broad country-level ownership of the modelling data inputs and results. In turn, it stimulates discussions and a review of the current evidence and assumptions, strengthening the decision-making process in general.TIME Impact has been effectively applied in a variety of settings. In South Africa, it informed the first South African HIV and TB Investment Cases and successfully leveraged additional resources from the National Treasury at a time of austerity. In Ghana, a long-term TIME model-centred interaction with the NTP provided new insights into the local epidemiology and guided resource allocation decisions to improve impact. PMID:27012808

  14. Global monitoring of collaborative TB-HIV activities.

    PubMed

    Gunneberg, C; Reid, A; Williams, B G; Floyd, K; Nunn, P

    2008-03-01

    Tuberculosis (TB) and human immunodeficiency virus (HIV) programs are increasingly working together towards providing universal access to integrated TB and HIV prevention, treatment, care and support services. To monitor progress we need to measure the delivery and impact of these services; however, the lack of investment in monitoring and evaluation and the added complexity of sharing data between two vertical programs, makes monitoring and evaluation of collaborative TB-HIV activities especially challenging. We describe the global system to record, report and analyse data on collaborative TB-HIV activities and summarize results to date. Although the data suggest that there is a steady increase in collaborative TB-HIV activities in many high-burden countries over time, we are already falling behind the globally agreed implementation milestones. This is due to a combination of slow implementation and lack of necessary tools and systems for capturing activity data. In particular, data from HIV program monitoring of TB screening, TB preventive treatments and TB infection control for people living with HIV is lacking. Much remains to be done by both programs to improve the implementation, monitoring and evaluation of collaborative TB-HIV activities and to optimize prevention, treatment and care for people infected with both TB and HIV, especially in areas at high risk of drug-resistant TB. PMID:18302815

  15. Effect of Dy/Nd double layer on coercivity in Nd-Fe-B thin films

    SciTech Connect

    Koike, K. Umezawa, J.; Ishikawa, H.; Ogawa, D.; Mizuno, Y.; Kato, H.; Miyazaki, T.; Ando, Y.

    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.

  16. TB control in Singapore: where do we go from here?

    PubMed

    Chee, Cynthia Bin-Eng; Wang, Yee Tang

    2012-04-01

    The total number of new tuberculosis (TB) cases notified in Singapore among citizens, permanent residents and foreigners rose by 46% from 2004 to 2010. During this period, the proportion of foreigners increased from 29% to 47% of the total case burden. In 2008, the TB incidence rate among Singapore citizens and permanent residents increased for the first time in ten years, despite the on-going efforts of the Singapore TB Elimination Programme. Additional measures and resources are clearly needed to curb this rising trend. Pivotal to this is to address TB among foreigners. The political will to battle TB in Singapore must result in action to remove barriers to diagnosis, to enable all TB patients to undergo treatment under directly observed therapy (DOT), and to ensure that all healthcare providers who manage TB patients are responsible and accountable to the public health system. PMID:22511043

  17. 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

  18. (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.

  19. Uniform hollow Lu2O3:Ln (Ln = Eu3+, Tb3+) spheres: facile synthesis and luminescent properties.

    PubMed

    Yang, Piaoping; Gai, Shili; Liu, Yanchao; Wang, Wenxin; Li, Chunxia; Lin, Jun

    2011-03-21

    Uniform hollow Lu(2)O(3):Ln (Ln = Eu(3+), Tb(3+)) phosphors have been successfully prepared via a urea-assisted homogeneous precipitation method using carbon spheres as templates, followed by a subsequent calcination process. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed infrared (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), photoluminescence (PL) spectra, cathodoluminescence (CL) spectra, kinetic decays, quantum yields (QY), and UV-visible diffuse reflectance spectra were employed to characterize the samples. The results show that hollow Lu(2)O(3):Ln spheres can be indexed to cubic Gd(2)O(3) phase with high purity. The as-prepared hollow Lu(2)O(3):Ln phosphors are confirmed to be uniform in shape and size with diameter of about 300 nm and shell thickness of approximate 20 nm. The possible formation mechanism of evolution from the carbon spheres to the amorphous precursor and to the final hollow Lu(2)O(3):Ln microspheres has been proposed. Upon ultraviolet (UV) and low-voltage electron beams excitation, the hollow Lu(2)O(3):Ln (Ln = Eu(3+), Tb(3+)) spheres exhibit bright red (Eu(3+), (5)D(0)-(7)F(2)) and green (Tb(3+), (5)D(4)-(7)F(5)) luminescence, which may find potential applications in the fields of color display and biomedicine. PMID:21323378

  20. Decay properties of long-lived isomers in the odd-odd N=81 nucleus {sup 146}Tb compared to the {sup 148}Ho and {sup 150}Tm nuclei

    SciTech Connect

    Kownacki, J.; Kisielinski, M.; Droste, Ch.; Morek, T.; Ruchowska, E.; Grodner, E.; Lieder, R. M.; Kowalczyk, M.; Wrzosek-Lipska, K.; Hadynska-KlePk, K.; Mierzejewski, J.; Andrzejewski, J.; Perkowski, J.; Napiorkowski, P. J.; Zielinska, M.; Kordyasz, A.; Srebrny, J.; Korman, A.

    2011-02-15

    Excited states of the {sup 146}Tb nucleus have been studied using {gamma}-ray and electron spectroscopy in off-beam and in-beam modes following {sup 112}Sn({sup 40}Ar,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{sup -}) level in {sup 146}Tb shows mainly an E2 nature and the first excited state above the 23 s isomer is assigned as a (5{sup -},6{sup -}) state. The log ft values have been deduced for 11 {beta}{sup +}/EC transitions populating excited states in {sup 146}Gd. 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 {sup 146}Tb, {sup 148}Ho, and {sup 150}Tm is discussed.

  1. Experimental investigation on the enthalpies of formation of the DyFe{sub 2}, DyFe{sub 3}, Dy{sub 2}Fe{sub 17}, ErFe{sub 2}, and ErFe{sub 3} intermetallic compounds

    SciTech Connect

    Norgren, S.; Hodaj, F.; Colinet, C.

    1998-05-01

    The enthalpies of formation at 298.15 K for five intermetallic phases in the Fe-Dy and Fe-Er binary systems have been determined by indirect solution calorimetry in liquid aluminum at 1,100 K. The phases were Fe{sub 2}Dy, Fe{sub 3}Dy, and Fe{sub 17}Dy{sub 2} in the Fe-Dy system and Fe{sub 2}Er and Fe{sub 3}Er in the Fe-Er system. The following mean values of {Delta}{sub f}H{sub 298.15 K} are reported: {minus}11.1 kJ/mole for Fe{sub 2/3}Dy{sub 1/3}, {minus}7.7 kJ/mole for Fe{sub 3/4}Dy{sub 1/4}, {minus}1.9 kJ/mole for Fe{sub 17/19}Dy{sub 2/19}, {minus}12.5 kJ/mole for Fe{sub 2/3}Er{sub 1/3}, and {minus}7.9 kJ/mole for Fe{sub 3/4}Er{sub 1/4}. The measured enthalpies of formation of the Fe{sub 2}Dy and Fe{sub 2}Er compounds are almost equal, as are the enthalpies of formation of the Fe{sub 3}Dy and Fe{sub 3}Er compounds. The results are compared with earlier experimental data, with values predicted by Miedema`s semiempirical method and with calculated results obtained by Colinet and Pasturel using a tight binding model.

  2. [Present and future perspectives for the rapid molecular diagnosis of TB and MDR-TB].

    PubMed

    Tanasescu, Mihaela; Didilescu, Cristian; Marica, Constantin

    2013-01-01

    Tuberculosis is still one of the diseases with a major medical and social impact, and in terms of early diagnosis (which would imply a fair treatment and established at the time), difficulties related to the delay bacilli isolation in culture, decreased susceptibility testing methods to antituberculosis drugs, lack of methods for differentiation of M. Tuberculosis complex germs of non-TB Mycobacteria, may have important clinical implications. Traditional testing of anti-TB drug susceptibility on solid Löwenstein-Jensen medium (gold standard) or liquid media can only be performed using grown samples. Determining the time it takes up to 42 days on solid media and 12 days for liquid media. For MDR/XDR TB cases itis absolutely essential to reduce the detection time. In these cases rapid diagnostic methods prove their usefulness. Automatic testing in liquid medium, molecular hybridization methods are currently recommended by the current WHO guidelines. Rapid diagnosis of MDR-TBis extremely useful for the early establishment of an effective treatment tailored more accurately on the spectrum of sensitivity of the resistant strain (thus reducing the risk of developing additional resistance to other drugs) and control the spread of these strains. Genetic diagnostic methods, approved and recommended by the WHO, can reduce the time of diagnosis of TB case and, importantly, the case of MDR-TB. They do not replace the current standard diagnostic methods and resistance profile, but complete them in selected cases. PMID:24734352

  3. Anion-templated assembly and magnetocaloric properties of a nanoscale {Gd38} cage versus a {Gd48} barrel.

    PubMed

    Guo, Fu-Sheng; Chen, Yan-Cong; Mao, Ling-Ling; Lin, Wei-Quan; Leng, Ji-Dong; Tarasenko, Róbert; Orendáč, Martin; Prokleška, Jan; Sechovský, Vladimír; Tong, Ming-Liang

    2013-10-25

    The comprehensive study reported herein provides compelling evidence that anion templates are the main driving force in the formation of two novel nanoscale lanthanide hydroxide clusters, {Gd38(ClO4)6} (1) and {Gd48Cl2(NO3)} (2), characterized by single-crystal X-ray crystallography, infrared spectroscopy, and magnetic measurements. {Gd38(ClO4)6}, encapsulating six ClO4(-) ions, features a cage core composed of twelve vertex-sharing {Gd4} tetrahedrons and one Gd⋅⋅⋅Gd pillar. When Cl(-) and NO3(-) were incorporated in the reaction instead of ClO4(-), {Gd48Cl2(NO3)} is obtained with a barrel shape constituted by twelve vertex-sharing {Gd4} tetrahedrons and six {Gd5} pyramids. What is more, the cage-like {Gd38} can be dynamically converted into the barrel-shaped {Gd48} upon Cl(-) and NO3(-) stimulus. To our knowledge, it is the first time that the linear M-O-M' fashion and the unique μ8-ClO4(-) mode have been crystallized in pure lanthanide complex, and complex 2 represents the largest gadolinium cluster. Both of the complexes display large magnetocaloric effect in units of J kg(-1) K(-1) and mJ cm(-3) K(-1) on account of the weak antiferromagnetic exchange, the high N(Gd)/M(W) ratio (magnetic density), and the relatively compact crystal lattice (mass density). PMID:24105852

  4. Basidiomycete DyPs: Genomic diversity, structural-functional aspects, reaction mechanism and environmental significance.

    PubMed

    Linde, Dolores; Ruiz-Dueas, Francisco J; Fernndez-Fueyo, Elena; Guallar, Victor; Hammel, Kenneth E; Pogni, Rebecca; Martnez, 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

  5. Comparisons of the Odd-Even Staggering Patterns Between the Ba-Dy Region with 88 Neutrons and ra Isotopes with 88 Protons

    NASA Astrophysics Data System (ADS)

    Mheemeed, Ahmed K.

    2013-09-01

    Useful information about the shape transitions of even-even isotones 144Ba, 146Ce, 148Nd, 150Sm, 152Gd, 154Dy with 88 neutrons and 218-226Ra isotopes with 88 protons are obtained from the ratios of E(4+1)/E(2^+_1) as a function of neutron number N or proton number Z and the relations E(I+1)/E(2^+_1) and r((I+2)/I) as a function of the angular momentum I. Interacting Boson Model (IBM-1), Bohr-Mottelson Model (BM) and Interacting Vector Boson Model (IVBM) have been employed to study the energy levels for the ground and octupole bands of the above nuclei. The best input parameters for the above approaches which lead to the best fit to experimental data are determined. The ΔI = 1 staggering (odd-even staggering) in octupole bands of the studied nuclei is found to exhibit a "beat" behavior as a function of angular momentum I. Comparisons of the displacement energies δE(I) and the staggering factor ΔE1, γ(I) are presented between the Ba-Dy region with 88 neutrons and Ra isotopes with 88 protons.

  6. Characteristics of Patients with Smear-Negative Pulmonary Tuberculosis (TB) in a Region with High TB and HIV Prevalence

    PubMed Central

    Campos, Leandro Cruz; Rocha, Marcos Vinícius Vieira; Willers, Denise Maria Cunha; Silva, Denise Rossato

    2016-01-01

    Introduction Smear-negative pulmonary TB (SNPT) represents 30–60% of all pulmonary TB cases. The mortality of these patients can reach 25% in populations with high prevalence of HIV infection, and 10–20% of TB transmission at the population level are attributable to SNPT cases. Methods We conducted a retrospective study to evaluate epidemiological, clinical, and radiological characteristics of patients with SNPT and to compare these with patients who were diagnosed as having smear-positive pulmonary TB (SPPT). All adult patients (≥ 18 years old) with a positive culture for Mycobacterium tuberculosis, and a diagnosis of pulmonary TB were included in the study. Results 198 patients met the inclusion criteria (positive culture for Mycobacterium tuberculosis) and were included in the analysis. Of these patients, 69 (34.8%) were smear positive (SPPT) and 129 (65.2%) were smear negative (SNPT). In univariate analysis, cough, dyspnea, and hemoptysis were less frequent in SNPT patients in comparison with SPPT patients. In a multivariate model, having no cough and no radiographic pattern typical of TB were the characteristics independently associated with a diagnosis of SNPT. Conclusions We found a very high prevalence of SNPT among patients with TB in a setting with high TB and HIV prevalence. The absence of cough in the presence of other symptoms suggestive of TB, and having no radiographic pattern typical of TB where independent predictors of SNPT. PMID:26808299

  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 showi ng how the AGCs relate to the SDR input power, and provide recommendations for AGC testing and characterization.

  8. 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.

  9. An Imbalanced Learning based MDR-TB Early Warning System.

    PubMed

    Li, Sheng; Tang, Bo; He, Haibo

    2016-07-01

    As a man-made disease, multidrug-resistant tuberculosis (MDR-TB) is mainly caused by improper treatment programs and poor patient supervision, most of which could be prevented. According to the daily treatment and inspection records of tuberculosis (TB) cases, this study focuses on establishing a warning system which could early evaluate the risk of TB patients converting to MDR-TB using machine learning methods. Different imbalanced sampling strategies and classification methods were compared due to the disparity between the number of TB cases and MDR-TB cases in historical data. The final results show that the relative optimal predictions results can be obtained by adopting CART-USBagg classification model in the first 90 days of half of a standardized treatment process. PMID:27209184

  10. Magnetic properties of Dy2Ti2O7

    NASA Technical Reports Server (NTRS)

    Flood, D. J.

    1973-01-01

    Measurements were made of the magnetization, differential magnetic susceptibility, and magnetic entropy of powered samples of Dy2Ti2O7. The saturation magnetic moment is 4.7 + or - 0.2 Bohr magnetons per Dy ion, instead of 10 as predicted by Hund's rules. A temperature-independent magnetization is observed in the saturation region. Absolute values of magnetic entropy have been obtained for temperatures from 1.25 to 20 K, in applied fields up to 10.4 tesla. The magnetic entropy approaches a maximum value consistent with a ground-state multiplicity of 2. Low field magnetization and differential susceptibility data show a transition to antiferromagnetism near 1.35 K. A construction of the magnetic specific heat from the zero field entropy shows an anomaly near the same temperature.

  11. 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.

  12. A PERIOD INVESTIGATION OF THE SX PHOENICIS STAR DY PEGASI

    SciTech Connect

    Li, L.-J.; Qian, S.-B.

    2010-06-15

    We measure two new times of light maximum of the SX Phoenicis star DY Pegasi in 2008 December and collect 410 pe/CCD times of light maximum that had been published. These data could be modeled with a nonlinear fit including a continuously decreasing period change (dP/dt = -9.04 x 10{sup -12} days day{sup -1}) and a periodic change with a period of 42.2 yr. If this periodic change is caused by the light traveling time effect of an orbital motion of DY Pegasi in a binary system, the deduced mass of the companion could be 0.028 M{sub sun} and it is probably a brown dwarf.

  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. High-field magnetization of Dy2O3

    NASA Technical Reports Server (NTRS)

    Flood, D. J.

    1974-01-01

    The magnetization of powdered samples of Dy2O3 has been measured at temperatures between 1.45 deg and 4.2 K, in applied magnetic fields ranging to 7 Teslas. A linear dependence of magnetization on applied field is observable in high field region, the slope of which is independent of temperature over the range investigated. The extrapolated saturation magnetic moment is 2.77 + or - 0.08 Bohr magnetons per ion.

  15. Novel gold nanocluster electrochemiluminescence immunosensors based on nanoporous NiGd-Ni2O3-Gd2O3 alloys.

    PubMed

    Lv, Xiaohui; Ma, Hongmin; Wu, Dan; Yan, Tao; Ji, Lei; Liu, Yixin; Pang, Xuehui; Du, Bin; Wei, Qin

    2016-01-15

    Herein, three-dimensional nanoporous NiGd alloy (NP-NiGd) was prepared by selectively dealloy Al from NiGdAl alloy in mild alkaline solution, then Ni2O3 and Gd2O3 grew further on the surface of NP-NiGd to obtain the NP-NiGd-Ni2O3-Gd2O3. On this basis, NP-NiGd-Ni2O3-Gd2O3 was further functionalized with gold nanoparticles (NP-NiGd-Ni2O3-Gd2O3@Au) and acted as sensor platform to fabricate a novel electrochemiluminescence (ECL) immunosensor. Bovine serum albumin protected gold nanoclusters (AuNCs@BSA) were prepared and acted as illuminant. AuNCs@BSA modified graphene oxide (GO/AuNCs@BSA) were used as labels of second antibody. In order to characterize the performance of the ECL immunosensor, carcino embryonie antigen (CEA) was used as the model to complete the experiments. Due to the good performances of NP-NiGd-Ni2O3-Gd2O3@Au (high surface area, excellent electron conductivity) and AuNCs@BSA (low toxicity, biocompatibility, easy preparation and good water solubility), the ECL immunosensor exhibited a wide range from 10(-4) to 5ng/mL with a detection limit of 0.03pg/mL (S/N=3). The immunosensor with excellent stability, acceptable repeatability and selectivity provided a promising method to detect CEA in human serum sample sensitively. PMID:26318782

  16. Mechanical properties of DyBaCuO superconducting bulks

    NASA Astrophysics Data System (ADS)

    Fujimoto, H.; Shimada, H.; Yoshizawa, S.

    2007-10-01

    Melt-processed REBaCuO (RE: rare earth) superconductors have a high Jc at 77 K and a high magnetic field, which are expected to be used for high field applications such as superconducting permanent magnets with liquid nitrogen refrigeration, flywheels, current leads and so on. Mechanical properties such as flexural strength, fracture toughness and ductility are very crucial as well as the superconducting properties: Tc, Jc, and Hirr for industrial applications of high-Tc oxide superconductors. However, oxide superconductors have the intrinsic brittleness of the perovskite structure, thus, the strength and the fracture toughness of REBaCuO superconductors have been reported to be low and anisotropic. Therefore, we should investigate and improve mechanical properties to achieve structural reliability for applications. Large single domain of melt-processed REBaCuO (Dy-123) superconductors with Dy2BaCuO5 (Dy-211) particles and Ag2O of 10 wt% was fabricated with a seeding and temperature gradient method in air. In this study, we discuss mechanical properties such as the hardness and the surface roughness, and the flexural strength of the RE-123 bulk, measured at RT. The results of Vickers hardness, surface roughness and the flexural strength showed very important information for evaluating characteristics of RE-123 bulks.

  17. Effect of Ligand Substitution around the Dy(III) on the SMM Properties of Dual-Luminescent Zn-Dy and Zn-Dy-Zn Complexes with Large Anisotropy Energy Barriers: A Combined Theoretical and Experimental Magnetostructural Study.

    PubMed

    Costes, Jean Pierre; Titos-Padilla, Silvia; Oyarzabal, Itziar; Gupta, Tulika; Duhayon, Carine; Rajaraman, Gopalan; Colacio, Enrique

    2016-05-01

    The new dinuclear Zn(II)-Dy(III) and trinuclear Zn(II)-Dy(III)-Zn(II) complexes of formula [(LZnBrDy(ovan) (NO3)(H2O)](H2O)·0.5(MeOH) (1) and [(L(1)ZnBr)2Dy(MeOH)2](ClO4) (3) (L and L(1) are the dideprotonated forms of the N,N'-2,2-dimethylpropylenedi(3-methoxysalicylideneiminato and 2-{(E)-[(3-{[(2E,3E)-3-(hydroxyimino)butan-2-ylidene ]amino}-2,2-dimethylpropyl)imino]methyl}-6-methoxyphenol Schiff base compartmental ligands, respectively) have been prepared and magnetostructurally characterized. The X-ray structure of 1 indicates that the Dy(III) ion exhibits a DyO9 coordination sphere, which is made from four O atoms coming from the compartmental ligand (two methoxy terminal groups and two phenoxido bridging groups connecting Zn(II) and Dy(III) ions), other four atoms belonging to the chelating nitrato and ovanillin ligands, and the last one coming to the coordinated water molecule. The structure of 3 shows the central Dy(III) ion surrounded by two L(1)Zn units, so that the Dy(III) and Zn(II) ions are linked by phenoxido/oximato bridging groups. The Dy ion is eight-coordinated by the six O atoms afforded by two L(1) ligands and two O atoms coming from two methanol molecules. Alternating current (AC) dynamic magnetic measurements of 1, 3, and the previously reported dinuclear [LZnClDy(thd)2] (2) complex (where thd = 2,2,6,6-tetramethyl-3,5-heptanedionato ligand) indicate single molecule magnet (SMM) behavior for all these complexes with large thermal energy barriers for the reversal of the magnetization and butterfly-shaped hysteresis loops at 2 K. Ab initio calculations on 1-3 show a pure Ising ground state for all of them, which induces almost completely suppressed quantum tunnelling magnetization (QTM), and thermally assisted quantum tunnelling magnetization (TA-QTM) relaxations via the first excited Kramers doublet, leading to large energy barriers, thus supporting the observation of SMM behavior. The comparison between the experimental and theoretical magnetostructural data for 1-3 has allowed us to draw some conclusions about the influence of ligand substitution around the Dy(III) on the SMM properties. Finally, these SMMs exhibit metal- and ligand-centered dual emissions in the visible region, and, therefore, they can be considered as magnetoluminescent bifunctional molecular materials. PMID:27078745

  18. 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-(β-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

  19. Neutron capture cross sections of {sup 148}Gd and the decay of {sup 149}Gd

    SciTech Connect

    Rios, M. G.; Casperson, R. J.; Krane, K. S.; Norman, E. B.

    2006-10-15

    The thermal cross section and resonance integral were measured for radiative neutron capture by radioactive {sup 148}Gd. The deduced values are {sigma}=9600{+-}900 b and I=28,200{+-}2300. We also deduced upper limits for the n,p and n, {alpha} cross sections, respectively, 0.25 b and 13 b. The {gamma}-ray spectrum from the decay of {sup 149}Gd was studied in singles mode at high resolution to verify the previously determined energies and intensities. From the latter measurements, new transitions are proposed and upper limits are deduced for previously reported transitions.

  20. Gd(-) Muret and gd(-) Colomiers, two new variants of glucose-6-phosphate dehydrogenase associated with favism.

    PubMed

    Vergnes, H; Ribet, A; Bommelaer, G; Amadieu, J; Brun, H

    1981-01-01

    Two males subjects are described with hitherto undescribed glucose-6-phosphate dehydrogenase (G6PD) variants. The first is of French ancestry, the second of Sicilian extraction. Each subject suffered from acute hemolytic anemia following ingestion of broad beans (Vicia fava). In both cases the hemolytic crisis occurred in a late period of life (29 and 58 years). No previous hemolytic crisis was recorded. The electrophoretic and kinetic properties of the mutant enzymes examined after purification from the red cells allowed each to be distinguished from other G6PD variants reported until now. The first variant was named Gd(-) Muret, the other Gd(-) Colomiers. PMID:7250973

  1. Gd(III)-Gd(III) distance measurements with chirp pump pulses.

    PubMed

    Doll, Andrin; Qi, Mian; Wili, Nino; Pribitzer, Stephan; Godt, Adelheid; Jeschke, Gunnar

    2015-10-01

    The broad EPR spectrum of Gd(III) spin labels restricts the dipolar modulation depth in distance measurements between Gd(III) pairs to a few percent. To overcome this limitation, frequency-swept chirp pulses are utilized as pump pulses in the DEER experiment. Using a model system with 3.4 nm Gd-Gd distance, application of one single chirp pump pulse at Q-band frequencies leads to modulation depths beyond 10%. However, the larger modulation depth is counteracted by a reduction of the absolute echo intensity due to the pump pulse. As supported by spin dynamics simulations, this effect is primarily driven by signal loss to double-quantum coherence and specific to the Gd(III) high spin state of S=7/2. In order to balance modulation depth and echo intensity for optimum sensitivity, a simple experimental procedure is proposed. An additional improvement by 25% in DEER sensitivity is achieved with two consecutive chirp pump pulses. These pulses pump the Gd(III) spectrum symmetrically around the observation position, therefore mutually compensating for dynamical Bloch-Siegert phase shifts at the observer spins. The improved sensitivity of the DEER data with modulation depths on the order of 20% is due to mitigation of the echo reduction effects by the consecutive pump pulses. In particular, the second pump pulse does not lead to additional signal loss if perfect inversion is assumed. Moreover, the compensation of the dynamical Bloch-Siegert phase prevents signal loss due to spatial dependence of the dynamical phase, which is caused by inhomogeneities in the driving field. The new methodology is combined with pre-polarization techniques to measure long distances up to 8.6 nm, where signal intensity and modulation depth become attenuated by long dipolar evolution windows. In addition, the influence of the zero-field splitting parameters on the echo intensity is studied with simulations. Herein, larger sensitivity is anticipated for Gd(III) complexes with zero-field splitting that is smaller than for the employed Gd-PyMTA complex. PMID:26340436

  2. Gd(III)-Gd(III) distance measurements with chirp pump pulses

    NASA Astrophysics Data System (ADS)

    Doll, Andrin; Qi, Mian; Wili, Nino; Pribitzer, Stephan; Godt, Adelheid; Jeschke, Gunnar

    2015-10-01

    The broad EPR spectrum of Gd(III) spin labels restricts the dipolar modulation depth in distance measurements between Gd(III) pairs to a few percent. To overcome this limitation, frequency-swept chirp pulses are utilized as pump pulses in the DEER experiment. Using a model system with 3.4 nm Gd-Gd distance, application of one single chirp pump pulse at Q-band frequencies leads to modulation depths beyond 10%. However, the larger modulation depth is counteracted by a reduction of the absolute echo intensity due to the pump pulse. As supported by spin dynamics simulations, this effect is primarily driven by signal loss to double-quantum coherence and specific to the Gd(III) high spin state of S = 7/2. In order to balance modulation depth and echo intensity for optimum sensitivity, a simple experimental procedure is proposed. An additional improvement by 25% in DEER sensitivity is achieved with two consecutive chirp pump pulses. These pulses pump the Gd(III) spectrum symmetrically around the observation position, therefore mutually compensating for dynamical Bloch-Siegert phase shifts at the observer spins. The improved sensitivity of the DEER data with modulation depths on the order of 20% is due to mitigation of the echo reduction effects by the consecutive pump pulses. In particular, the second pump pulse does not lead to additional signal loss if perfect inversion is assumed. Moreover, the compensation of the dynamical Bloch-Siegert phase prevents signal loss due to spatial dependence of the dynamical phase, which is caused by inhomogeneities in the driving field. The new methodology is combined with pre-polarization techniques to measure long distances up to 8.6 nm, where signal intensity and modulation depth become attenuated by long dipolar evolution windows. In addition, the influence of the zero-field splitting parameters on the echo intensity is studied with simulations. Herein, larger sensitivity is anticipated for Gd(III) complexes with zero-field splitting that is smaller than for the employed Gd-PyMTA complex.

  3. Some interesting observations regarding TB patient management from a rural area of Madhya Pradesh: TB case series

    PubMed Central

    Singh, Akash Ranjan; Pakhare, Abhijit; Chauhan, Ashish; Singh, Abhishek

    2015-01-01

    Despite many serious efforts, tuberculosis (TB) is still a recognized public health problem. The Government of India has adopted the Directly Observed Treatment, Short-Course (DOTS) strategy for the entire country through the Revised National Tuberculosis Control Programme (RNTCP) for the treatment of TB. In this report, we have presented the trajectories for care seeking of two TB cases who suffered from either “patient level delays” or “health system-related delays” in seeking DOTS for the treatment of TB.

  4. 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. PMID:26175780

  5. Supporting clinical management of the difficult-to-treat TB cases: the ERS-WHO TB Consilium.

    PubMed

    D'Ambrosio, Lia; Tadolini, Marina; Centis, Rosella; Duarte, Raquel; Sotgiu, Giovanni; Aliberti, Stefano; Dara, Masoud; Migliori, Giovanni Battista

    2015-03-01

    Multi-drug and extensively drug-resistant tuberculosis (MDR/XDR-TB) are considered a serious threat for TB control and elimination. The outcome of these patients is still largely unsatisfactory as of today, with treatment success rates being consistently below 50% at global level. The World Health Organization (WHO) recommends that management of MDR-TB cases is supported by a specialized team, including complementary medical professionals able to cover several perspectives (clinical, both for adults and children; surgical; radiological; public health; psychological; nursing, among others). Implementation of such a body (known as Consilium in most of the former Soviet Union countries) is often a pre-requisite to apply for international TB control funding and concessionally priced medicines to treat M/XDR-TB cases. The primary objective of the ERS/WHO TB Consilium is to provide clinical consultation for drug-resistant TB and other difficult-to-treat TB cases, including co-infection with HIV and paediatric cases. Through technical guidance to clinicians managing complex TB cases, the main contribution and outcome of the initiative will be a public health response aimed at achieving correct treatment of affected patients and preventing further development of drug resistance. The Consilum's secondary objective is to ensure monitoring and evaluation of clinical practices on the ground (diagnosis, treatment and prevention). PMID:25809773

  6. 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

  7. Polarization enhancement and ferroelectric switching enabled by interacting magnetic structures in DyMnO3 thin films

    NASA Astrophysics Data System (ADS)

    Lu, Chengliang; Dong, Shuai; Xia, Zhengcai; Luo, Hui; Yan, Zhibo; Wang, Haowen; Tian, Zhaoming; Yuan, Songliu; Wu, Tao; Liu, Junming

    2013-12-01

    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.

  8. 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.

  9. 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.

  10. 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

  11. Thermal neutron cross-section and resonance integral for 164Dy(n,γ) 165Dy reaction

    NASA Astrophysics Data System (ADS)

    Karadag, Mustafa; Yücel, Haluk

    2005-09-01

    The thermal neutron cross-section ( σ0) and the resonance integral ( I0) of the reaction 164Dy(n,γ) 165Dy were measured by the activation method, using 55Mn(n,γ) 55Mn monitor reaction as a single comparator. The diluted MnO 2 and Dy 2O 3 powder samples within and without a cylindrical Cd shield case were irradiated in an isotropic neutron field obtained from the 241Am-Be neutron sources, moderated with paraffin wax. The γ-ray spectra from the irradiated samples were measured by high-resolution γ-ray spectrometry with a calibrated n-type Ge detector. The necessary correction factors for γ-ray attenuation, thermal neutron and resonance neutron self-shielding effects and epithermal neutron spectrum shape factor (α) were taken into account in the determinations. The thermal neutron cross-section for 164Dy(n,γ) 165Dy reaction studied has been determined to be 2672±104 b at 0.025 eV. This result has been obtained relative to the reference thermal neutron cross-section value of 13.3±0.1 b for the 55Mn(n,γ) 56Mn reaction. For the thermal neutron cross-section, most of the experimental data and evaluated one in ENDF/B-VI, in general, are in good agreement with the present result. The resonance integral has also been measured relative to the reference value of 14.0±0.3 b for the 55Mn(n,γ) 56Mn monitor reaction using a 1/ E1+α epithermal neutron spectrum of the 241Am-Be neutron source. By defining Cd cut-off energy 0.55 eV, the resonance integral obtained was 527±89 b. The existing experimental and evaluated data for the resonance integral are distributed from 335 to 820 b. The present resonance integral value agrees with some previously reported values, 520 b by Holden, 505 b by Simonits et al. and 575±100 b by Heft, within the limits of error.

  12. The hydrogenation of Dy{sub 5}Pd{sub 2} followed by in situ methods

    SciTech Connect

    Kohlmann, H.; Talik, E.; Hansen, T.C.

    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.

  13. High-temperature X-ray diffraction measurements of fluorite-related rare earth antimonates Ln{sub 3}SbO{sub 7} (Ln=Nd, Tb) and their magnetic properties

    SciTech Connect

    Hinatsu, Yukio Doi, Yoshihiro

    2014-09-15

    Ternary rare-earth antimonates Ln{sub 3}SbO{sub 7} (Ln=rare earths) were prepared, and their structures were determined by X-ray diffraction measurements. They crystallize in an orthorhombic superstructure of cubic fluorite (space group Cmcm for Ln=La, Pr; Ccmm for Ln=Sm–Dy), in which Ln{sup 3+} ions occupy two different crystallographic sites (the 8-coordinated and 7-coordinated). For Ln=Nd, two phases with the Cmcm and Ccmm space groups coexist at room temperature. When the temperature was increased, the Nd{sub 3}SbO{sub 7} compound transformed into a single phase with the space group Cmcm. Through magnetic susceptibility measurements, an antiferromagnetic transition was observed at 3.0 K (Ln=Nd) and 7.8 K (Ln=Tb). Analysis of the magnetic specific heat for Tb{sub 3}SbO{sub 7} indicates that the 8-coordinated Tb ions magnetically orders at 7.8 K, and with furthermore decreasing temperature, the 7-coordinated Tb ions shows antiferromagnetic ordering at 3.0 K. - Graphical abstract: Temperature dependence of the specific heat divided by temperature (C{sub p}/T) and the magnetic entropy (S{sub mag}) for Tb{sub 3}SbO{sub 7}. Two-step magnetic transition has been observed. - Highlights: • The phase transition of Nd{sub 3}SbO{sub 7} is from the Ccmm space group to the Cmcm one. • Nd{sub 3}SbO{sub 7} shows an antiferromagnetic transition at 3.0 K. • For Tb{sub 3}SbO{sub 7}, two-step magnetic transition has been observed at 7.8 and 3.0 K.

  14. 46 CFR 38.05-20 - Insulation-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... strength for the proposed design. Additionally, the thermal expansion of the insulation relative to the... 46 Shipping 1 2010-10-01 2010-10-01 false Insulation-TB/ALL. 38.05-20 Section 38.05-20 Shipping... Installation § 38.05-20 Insulation—TB/ALL. (a) Where used, tank insulation shall satisfy the...

  15. 46 CFR 30.10-11 - Coastwise-TB/C.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Coastwise-TB/C. 30.10-11 Section 30.10-11 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-11 Coastwise—TB/C. Under this designation shall be included all tank vessels normally navigating the waters of...

  16. 46 CFR 30.10-11 - Coastwise-TB/C.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Coastwise-TB/C. 30.10-11 Section 30.10-11 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-11 Coastwise—TB/C. Under this designation shall be included all tank vessels normally navigating the waters of...

  17. 46 CFR 35.30-25 - Explosives-TB/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Explosives-TB/ALL. 35.30-25 Section 35.30-25 Shipping... Explosives—TB/ALL. Fulminates or other detonating compounds in bulk in dry condition; explosive compositions... other like explosives shall not be accepted, stored, stowed or transported on board tank vessels....

  18. 46 CFR 35.30-25 - Explosives-TB/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Explosives-TB/ALL. 35.30-25 Section 35.30-25 Shipping... Explosives—TB/ALL. Fulminates or other detonating compounds in bulk in dry condition; explosive compositions... other like explosives shall not be accepted, stored, stowed or transported on board tank vessels....

  19. 46 CFR 35.30-25 - Explosives-TB/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Explosives-TB/ALL. 35.30-25 Section 35.30-25 Shipping... Explosives—TB/ALL. Fulminates or other detonating compounds in bulk in dry condition; explosive compositions... other like explosives shall not be accepted, stored, stowed or transported on board tank vessels....

  20. 46 CFR 30.10-35 - Headquarters-TB/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Headquarters-TB/ALL. 30.10-35 Section 30.10-35 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-35 Headquarters—TB/ALL. The term Headquarters means the Office of the Commandant, U.S. Coast Guard, Washington,...