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Sample records for dy tb gd

  1. Changes of Tb Emission by Non-radiative Energy Transfer from Dy in Gd2O2S:Tb Phosphor

    NASA Astrophysics Data System (ADS)

    Saraee, Kh. Rezaee Ebrahim; Zadeh, M. Darvish; Mostajaboddavati, M.; Kharieky, A. Aghay

    2016-06-01

    In this study, the Gd2O2S:Tb1.5Dy x=0.3,0.6,0.9 nanophosphor were synthesized by the homogenous precipitation method followed with a sulfur reaction. The fluorescence of Gd2O2S:Tb1.5,Dy nanophosphors, and the energy transfer between dysprosium (Dy) and Tb have been studied. Although, the two weak emissions of Dy were observed, the terbium (Tb) emission was increased due to energy transfer from Dy ions to Tb ions. The results illustrated that the co-activator of Dy had a significant influence on the spectral properties of the Gd2O2S:Tb1.5 nanophosphor with an optimal amount of Dy (0.3 mol%). Moreover, Gd2O2S:Tb1.5 and Gd2O2S:Tb1.5,Dy nanophosphors screens were prepared with 10 mg/cm2 coating thickness. The scintillation properties of these screens have been investigated. We found a Gd2O2S:Tb1.5,Dy0.3 scintillator can be employed in x-ray imaging applications.

  2. 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

  3. 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

  4. High-Pressure Magnetic Susceptibility Experiments on the Heavy Lanthanides Gd, Tb, Dy, Ho, Er, and Tm

    SciTech Connect

    Jackson, D D; Malba, V; Weir, S T; Baker, P A; Vohra, Y K

    2004-11-19

    The high pressure magnetic properties of the heavy lanthanide elements Gd, Tb, Dy, Ho, Er, and Tm have been investigated using ac magnetic susceptibility with a diamond anvil cell. It is found that the magnetic transition temperatures monotonically decrease with increasing pressure. In addition, the amplitudes of the magnetic transition signals decrease with increasing pressure, with the signals all eventually disappearing at pressures by 20 GPa. In contrast to previous studies, we see no evidence of any pressure-induced transitions from one magnetically ordered phase to another in Gd, Tb, Dy, or Ho. The transition temperatures, T{sub crit} are all found to drop at a rate proportional to their de Gennes factor, and the values of T{sub crit}/T{sub crit}(P = 0) vs P/P{sub crit}, where P{sub crit} is the pressure where the magnetic transition disappears, all sit on a single phase diagram.

  5. Energy transfer and tunable multicolor emission and paramagnetic properties of GdF3:Dy(3+),Tb(3+),Eu(3+) phosphors.

    PubMed

    Guan, Hongxia; Sheng, Ye; Xu, Chengyi; Dai, Yunzhi; Xie, Xiaoming; Zou, Haifeng

    2016-07-20

    A series of Dy(3+), Tb(3+), Eu(3+) singly or doubly or triply doped GdF3 phosphors were synthesized by a glutamic acid assisted one-step hydrothermal method. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and photoluminescence (PL) spectroscopy. The results show that the synthesized samples are all pure GdF3. The obtained samples have a peanut-like morphology with a diameter of about 270 nm and a length of about 600 nm. Under UV excitation, GdF3:Dy(3+), GdF3:Tb(3+) and GdF3:Eu(3+) samples exhibit strong blue, green and red emissions, respectively. By adjusting their relative doping concentrations in the GdF3 host, the different color hues of green and red light are obtained by co-doped Dy(3+), Tb(3+) and Tb(3+), Eu(3+) ions in the GdF3 host, respectively. Besides, there exist two energy transfer pairs in the GdF3 host: (1) Dy(3+) → Tb(3+) and (2) Tb(3+) → Eu(3+). More significantly, in the Dy(3+), Tb(3+), and Eu(3+) tri-doped GdF3 phosphors, white light can also be achieved upon excitation of UV light by adjusting the doping concentration of Eu(3+). In addition, the obtained samples also exhibit paramagnetic properties at room temperature (300 K) and low temperature (2 K). It is obvious that multifunctional Dy(3+), Tb(3+), Eu(3+) tri-doped GdF3 materials including tunable multicolors and intrinsic paramagnetic properties may have potential applications in the field of full-color displays. PMID:27388285

  6. 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.

  7. Optical spectroscopic study on new magnetoelectric hexagonal REMnO3 (RE=Gd, Tb, Dy, and Ho) thin films

    NASA Astrophysics Data System (ADS)

    Choi, Woo Seok; Seo, Sung Seok A.; Lee, Jung Hyuk; Lee, Daesu; Noh, Tae Won; Lee, Yunsang

    2007-03-01

    Recently, magnetoelectric effects in various oxides have been attracting lots of attentions and are being extensively investigated due to their intriguing couplings between the magnetic and electric order parameters. Here we report optical spectroscopic investigations on new hexagonal REMnO3 (RE = Gd, Tb, Dy, and Ho) thin films, which are fabricated by epi-stabilization technique [1]. From the in-plane optical conductivity spectra of the hexagonal REMnO3, we observe a dramatic increase of the optical transition related to Mn 3d a1g energy level, as the ionic radius of the R ion increases. The optical transition at 1.64 eV for DyMnO3 shifts to 1.67 and 1.81 for TbMnO3 and GdMnO3 respectively. For natural hexagonal REMnO3 (RE = Y, Er, Lu, and Sc) with smaller ionic sizes, the same optical transitions occur at ˜1.6 eV. The large peak shift in new hexagonal REMnO3 is understood by local flattening of Mn-O bipyramid, which will enhance the crystal field energy of a1g, as the RE ionic size increases. [1] J. H. Lee et al., Adv. Mat., to be published (2006).

  8. 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.

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

    PubMed

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

    2014-09-14

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

  10. 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.

  11. 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

  12. Copper-indium ordering in RECu 6In 6 ( RE=Y, Ce, Pr, Nd, Gd, Tb, Dy)

    NASA Astrophysics Data System (ADS)

    Zaremba, Roman; Muts, Ihor; Hoffmann, Rolf-Dieter; Kalychak, Yaroslav M.; Zaremba, Vasyl' I.; Pöttgen, Rainer

    2007-09-01

    The rare earth metal-copper-indides RECu 6In 6 ( RE=Y, Ce, Pr, Nd, Gd, Tb, Dy) were synthesized from the elements by arc-melting. Well-crystallized samples were obtained by slowly cooling the melted buttons from 1320 to 670 K in sealed silica tubes in a muffle furnace. They were investigated by X-ray diffraction on powders and single crystals: ThMn 12 type, space group I4/ mmm, Z=2, a=916.3(2), c=535.8(2) pm, w R2=0.063, 216 F2 values, 15 variables for YCu 6In 6, a=926.5(4), c=543.5(3) pm, w R2=0.064, 314 F2 values, 15 variables for CeCu 6In 6, a=925.7(4), c=540.1(3) pm, w R2=0.075, 219 F2 values, 15 variables for PrCu 6In 6, a=923.1(4), c=540.3(3) pm, w R2=0.071, 218 F2 values, 15 variables for NdCu 6In 6, a=917.7(4), c=540.2(3) pm, w R2=0.076, 207 F2 values, 15 variables for GdCu 6In 6, a=917.0(5), c=540.5(4) pm, w R2=0.062, 215 F2 values, 15 variables for TbCu 6In 6, a=915.2(8), c=540.7(7) pm, w R2=0.108, 218 F2 values, 15 variables for DyCu 6In 6. The structures have been refined with a split position (50% Cu+50% In) for the 8 j site. They can be explained by a tetragonal body-centered packing of CN 20 polyhedra (10Cu+10In) around the rare earth atoms. The ordering models of the copper and indium atoms and the limitations/resolution of X-ray diffraction for this topic are discussed.

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

    PubMed

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

    2013-10-21

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

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

    DOE PAGESBeta

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

    2015-05-14

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

  16. 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

  17. 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.

  18. 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 Y0.60Gd0.38BO3: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. PMID:25991566

  19. 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.

  20. Magnetic properties of R2Co15Al2 compounds with R=Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm

    NASA Astrophysics Data System (ADS)

    Shen, Bao-gen; Cheng, Zhao-hua; Zhang, Shao-ying; Wang, Jing-yun; Liang, Bing; Zhang, Hong-wei; Zhan, Wen-shan

    1999-03-01

    An investigation of the structure and the magnetic anisotropy of R2Co15Al2 (R=Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm) compounds has been performed by means of x-ray diffraction and magnetization measurements. X-ray diffraction shows the prepared compounds to be single phase, having the hexagonal Th2Ni17-type structure for R=Y, Ho, Er, and Tm and the rhombohedral Th2Zn17-type structure for R=Ce, Pr, Nd, Gd, Tb, and Dy. Except for the Ce compound, the unit-cell volumes of R2Co15Al2 compounds decrease in accordance with the lanthanide contraction. Substitution of Al for Co in R2Co17 leads to a decrease of the saturation magnetization at 1.5 K and Curie temperature. The exchange-coupling constants JCo-Co and JR-Co have been calculated by using the method based on magnetic ordering temperature. It is found that the JR-Co has a small dependence on the R elements and is almost not affected by the Al substitution. The Ce compound is found to exhibit an anomalous lattice parameter and magnetic characteristic, which are relative to the mixed-valence behavior of the Ce ion. X-ray diffraction measurements on magnetically aligned R2Co15Al2 powders show that the compounds with R=Pr, Nd, Gd, Tb, Dy, and Ho have an easy-plane type of magnetic anisotropy, whereas the compounds with R=Y, Ce, Sm, Er, and Tm exhibit an easy-axis type of magnetic anisotropy at room temperature. The compounds R2Co15Al2 with R=Pr and Ho exhibit a spin-reorientation transition and the spin-reorientation temperature is found to be 531 and 431 K, respectively. A strong uniaxial anisotropy is observed in Sm2Co15Al2 compound with a magnetocrystalline anisotropy field of 84 kOe at room temperature.

  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. Electric Transport in R2MGe6 Ternary Compounds (R=La, Ce, Gd, Tb, Dy, Ho; M=Mn, Ni, Cu)

    SciTech Connect

    M. Konyk; B. Kuzhel; Yu. Stadnyk; Yu. Gorelenko; Ya. Mudryk; A. Waskiv

    2007-04-29

    Polycrystalline samples of the intermetallic compounds La{sub 2}MnGe{sub 6}, Ce{sub 2}MnGe{sub 6}, La{sub 2}CuGe{sub 6}, Ce{sub 2}CuGe{sub 6}, and R{sub 2}NiGe{sub 6} (R = Gd, Tb, Dy, Ho), which belong to the Ce{sub 2}CuGe{sub 6} type of structure (Amm2 or Cm2m space group), were studied by means of the electrical resistivity and differential thermopower measurements. They exhibit the metallic-like behavior in the temperature range from 5 to 290 K. The peculiarities in both resistivity and thermopower temperature dependencies correlate with corresponding magnetic transition T{sub tr} temperatures.

  3. 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

  4. Ab initio calculation of local magnetic moments and the crystal field in scrR2Fe14B (scrR=Gd, Tb, Dy, Ho, and Er)

    NASA Astrophysics Data System (ADS)

    Hummler, K.; Fähnle, M.

    1992-02-01

    The local magnetic moments and the valence contribution to the crystal-field parameter A02 at the rare-earth sites are calculated for scrR2Fe14B with scrR=Gd, Tb, Dy, Ho, and Er within the framework of the linear-muffin-tin-orbital theory and the local-spin-density approximation. Thereby, the 4f moments of scrR are calculated by the Russel-Saunders scheme, but the radial 4f spin density was part of the self-consistent density-functional calculation. The local moments as well as A02 averaged over the two crystallographically inequivalent scrR sites remain remarkably constant across the series.

  5. 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.

  6. 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.

  7. Magnetic hyperfine interactions on Cd sites of the rare-earth cadmium compounds R Cd (R =Ce , Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er)

    NASA Astrophysics Data System (ADS)

    Cavalcante, F. H. M.; Leite Neto, O. F. L. S.; Saitovitch, H.; Cavalcante, J. T. P. D.; Carbonari, A. W.; Saxena, R. N.; Bosch-Santos, B.; Pereira, L. F. D.; Mestnik-Filho, J.; Forker, M.

    2016-08-01

    This paper reports the investigation of the magnetic hyperfine field Bh f in a series of rare-earth (R ) cadmium intermetallic compounds R Cd and GdCd2 measured by perturbed angular correlation (PAC) spectroscopy using 111In/111Cd as probe nuclei at Cd sites as well as first-principles calculations of Bh f at Cd sites in the studied compounds. Vapor-solid state reaction of R metals with Cd vapor and the 111In radioisotope was found to be an appropriate route of doping rare-earth cadmium compounds with the PAC probe 111In/111Cd. The observation that the hyperfine parameters depend on details of the sample preparation provides information on the phase preference of diffusing 111In in the rare-earth cadmium phase system. The 111Cd hyperfine field has been determined in the compounds R Cd for the R constituents Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er, in several cases as a function of temperature. For most R constituents, the temperature dependence Bh f(T ) of 111Cd:R Cd is consistent with ferromagnetic order of the compound. DyCd, however, presents a remarkable anomaly: a finite magnetic hyperfine field is observed only in the temperature interval 35 K ≤ T ≤ 80 K which indicates a transition from ferromagnetic order to a spin arrangement where all 4 f -induced contributions to the magnetic hyperfine field at the Cd site cancel. First-principles calculation results for DyCd show that the (π , π , 0) antiferromagnetic configuration is energetically more favorable than the ferromagnetic. The approach used in the calculations to simulate the R Cd system successfully reproduces the experimental values of Bh f at Cd sites and shows that the main contribution to Bh f comes from the valence electron polarization. The de Gennes plot of the hyperfine field Bh f of 111Cd:R Cd vs the 4 f -spin projection (g -1 )J reflects a decrease of the strength of indirect 4 f -4 f exchange across the R series. Possible mechanisms are discussed and the experimental results indicate that

  8. 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.

  9. S-shaped decanuclear heterometallic [Ni8Ln2] complexes [Ln(III) = Gd, Tb, Dy and Ho]: theoretical modeling of the magnetic properties of the gadolinium analogue.

    PubMed

    Hossain, Sakiat; Das, Sourav; Chakraborty, Amit; Lloret, Francesc; Cano, Joan; Pardo, Emilio; Chandrasekhar, Vadapalli

    2014-07-14

    The reaction of 8-quinolinol-2-carboaldoxime (LH2) with Ni(II) and Ln(III) salts afforded the heterometallic decanuclear compounds [Ni8Dy2(μ3-OH)2(L)8(LH)2(H2O)6](ClO4)2·16H2O (1), [Ni8Gd2(μ3-OH)2(L)8(LH)2(H2O)4(MeOH)2](NO3)2·12H2O (2), [Ni8Ho2(μ3-OH)2(L)8(LH)2(H2O)4(MeOH)2](ClO4)2·2MeOH·12H2O (3) and [Ni8Tb2 (μ3-OH)2(L)8(LH)2(MeOH)4(OMe)2]·2CH2Cl2·8H2O (4). While compounds 1-3 are dicationic, compound 4 is neutral. These compounds possess an S-shaped architecture and comprise a long chain of metal ions bound to each other. In all the complexes, the eight Ni(II) and two Ln(III) ions of the multimetallic ensemble are hold together by two μ3-OH, eight dianionic (L(2-)) and two monoanionic oxime ligands (LH(-)) whereas compound 4 has two μ3-OH, eight dianionic (L(2-)), two monoanionic oxime ligands (LH(-)) and two terminal methoxy (MeO(-)) ligands. The central portion of the S-shaped molecular wire is made up of an octanuclear Ni(II) ensemble which has at its two ends the Ln(III) caps. Magnetic studies on 1-4 reveal that the magnetic interactions between neighboring metal ions are negligible at room temperature. On the other hand, at lower temperatures in all the compounds anti-ferromagnetic interactions seem to be dominated. Analysis of the magnetic data for the Gd(III) derivative indicates Ni(II)-Ni(II) anti-ferromagnetic interactions and Gd(III)-Ni(II) ferromagnetic interactions at low temperatures. A theoretical density functional study on the magnetic behavior of the Gd(III) derivative suggests that while the weak ferromagnetic interaction between Gd(III) and Ni(II) is in line with the expectation of the magnetic interactions between orthogonal d and f orbitals, antiferromagnetic Ni(II)-Ni(II) interactions are related to the wide Ni-O-Ni angles (∼102°) and quasi-planar conformation of the Ni2O2 core. PMID:24876072

  10. Evolution of lattice dynamics in ferroelectric hexagonal REInO3 (RE = Ho, Dy, Tb, Gd, Eu, Sm) perovskites

    NASA Astrophysics Data System (ADS)

    Paul, Barnita; Chatterjee, Swastika; Gop, Sumana; Roy, Anushree; Grover, Vinita; Shukla, Rakesh; Tyagi, A. K.

    2016-07-01

    Rare-earth indates emerge as one of the efficient geometric ferroelectric materials, in which the spontaneous polarization can be tuned by varying their crystal structure along the 4f rare-earth series. We report a systematic study of structural changes in hexagonal REInO3 perovskite (RE = Ho3+, Dy3+, Tb3+, Gd3+, Eu3+, Sm3+) and YInO3 of P63 cm space group by powder x-ray diffraction (XRD) and Raman scattering measurements. The crystal structure of these materials could be investigated by the Rietveld refinement of their XRD patterns. We have calculated density of states of phonons using density functional theory and examined the atomic displacements corresponding to observed Raman modes. The evolution of lattice dynamics of REInO3 has been probed by correlating various Raman modes with the structural distortion of the unit cell and the characteristics of the rare-earth ions. We report the appearance of the coupled mode in the phonon spectra. We have estimated spontaneous polarization from the structural distortion in this system and shown that it can be modulated by varying RE3+ ions in REInO3. We also report the appearance of a ferroelectric soft Raman mode, a unique characteristic of these materials.

  11. 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.

  12. 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

  13. 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.; Szelecsényi, F.; Kovács, 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.

  14. 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; 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.

  15. 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.

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

    SciTech Connect

    Zelinska, Mariya; Oryshchyn, Stepan; Zhak, Olga; Pivan, Jean-Yves; Potel, Michel; Tougait, Olivier; Noel, Henri; Kaczorowski, Dariusz

    2010-09-15

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

  17. Decay studies of neutron deficient nuclei near the Z=64 subshell: 142Dy, 140,142Tb, 140,142Gd, 140,142Eu, 142Sm, and 142Pm

    NASA Astrophysics Data System (ADS)

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

    1991-03-01

    The electron-capture and β+-decay branchings (EC/β+) and delayed proton decays of A=142 isotopes with 61<=Z<=66 and A=140 isotopes with 63<=Z<=65 were investigated with the OASIS facility on-line at the Lawrence Berkeley Laboratory SuperHILAC. Electron capture and positron-decay emission probabilities have been determined for 142Pm and 142Sm decays, and extensive decay schemes have been constructed for 142Eug(2.34+/-0.12 s), 142Gd(70.2+/-0.6 s), 140Eu(1.51+/-0.02 s), and 140Gd(15.8+/-0.4 s). Decay schemes for the new isotopes 142Tbg(597+/-17 ms), 142Tbm(303+/-17 ms), 142Dy(2.3+/-0.3 s), 140Eum(125+/-2 ms), and 140Tb(2.4+/-0.2 s) are also presented. We have assigned γ rays to these isotopes on the basis of γγ and xγ coincidences, and from half-life determinations. Electron-capture and β+-decay branchings were measured for each decay, and β-delayed proton branchings were determined for 142Dy, 142Tb, and 140Tb decays. QEC values, derived from the measured EC/β+ branchings and the level schemes are compared with those from the Wapstra and Audi mass evaluation and the Liran and Zeldes mass calculation. The systematics of the N=77 isomer decays are discussed, and the intense 0+-->1+ and 1+-->0+ ground-state beta decays are compared with shell-model predictions for simple spin-flip transitions.

  18. Magnetomechanical damping in cryogenic TbDy

    NASA Technical Reports Server (NTRS)

    Dooley, J.; Good, N.; White, C.; Leland, S.; Fultz, B.

    2002-01-01

    Vibration damping in polycrystalline TbDy alloys was studied at cryogenic temperatures. The material was prepared by cold-rolling to induce crystallographic texture, and was then heat-treated to relieve internal stress. Mechanical hysteretic losses were measured at various strains, frequencies, and loading configurations at 77 K. Some textured TbDy materials demonstrated 22.6% energy dissipation in mechanical measurements at low frequency (0.01 Hz) and a mean logarithmic decrement of 0.23 at a higher frequency (25 kHz). Ultrasonic velocities of longitudinal and shear elastic waves were measured on single and polycrystalline TbDy; little variation in ultrasonic velocities was found evenfor samples with large variation in crystallographic texture and magnetomechanical properties.

  19. Decay studies of neutron deficient nuclei near the Z =64 subshell: sup 142 Dy, sup 140,142 Tb, sup 140,142 Gd, sup 140,142 Eu, sup 142 Sm, and

    SciTech Connect

    Firestone, R.B.; Gilat, J.; Nitschke, J.M.; Wilmarth, P.A.; Vierinen, K.S. )

    1991-03-01

    The electron-capture and {beta}{sup +}-decay branchings (EC/{beta}{sup +}) and delayed proton decays of {ital A}=142 isotopes with 61{le}{ital Z}{le}66 and {ital A}=140 isotopes with 63{le}{ital Z}{le}65 were investigated with the OASIS facility on-line at the Lawrence Berkeley Laboratory SuperHILAC. Electron capture and positron-decay emission probabilities have been determined for {sup 142}Pm and {sup 142}Sm decays, and extensive decay schemes have been constructed for {sup 142}Eu{sup {ital g}}(2.34{plus minus}0.12 s), {sup 142}Gd(70.2{plus minus}0.6 s), {sup 140}Eu(1.51{plus minus}0.02 s), and {sup 140}Gd(15.8{plus minus}0.4 s). Decay schemes for the new isotopes {sup 142}Tb{sup {ital g}}(597{plus minus}17 ms), {sup 142}Tb{sup {ital m}}(303{plus minus}17 ms), {sup 142}Dy(2.3{plus minus}0.3 s), {sup 140}Eu{sup {ital m}}(125{plus minus}2 ms), and {sup 140}Tb(2.4{plus minus}0.2 s) are also presented. We have assigned {gamma} rays to these isotopes on the basis of {gamma}{gamma} and {ital x}{gamma} coincidences, and from half-life determinations. Electron-capture and {beta}{sup +}-decay branchings were measured for each decay, and {beta}-delayed proton branchings were determined for {sup 142}Dy, {sup 142}Tb, and {sup 140}Tb decays. {ital Q}{sub EC} values, derived from the measured EC/{beta}{sup +} branchings and the level schemes are compared with those from the Wapstra and Audi mass evaluation and the Liran and Zeldes mass calculation. The systematics of the {ital N}=77 isomer decays are discussed, and the intense 0{sup +}{r arrow}1{sup +} and 1{sup +}{r arrow}0{sup +} ground-state beta decays are compared with shell-model predictions for simple spin-flip transitions.

  20. 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

  1. Magnetic and magneto-optical properties of (Tb,Dy)Nd/FeCo multilayers (abstract)

    NASA Astrophysics Data System (ADS)

    Yu, X. Y.; Fujiwara, Y.; Watabe, H.; Iwata, S.; Tsunashima, S.; Uchiyama, S.

    1994-05-01

    Nd-Co and Nd-FeCo amorphous films are known to have larger Kerr rotation θk at shorter wavelength and ultraviolet light compared with other RE-TM (rare earth-transition) amorphous films. This property is desirable for MO (magneto-optical) media for the next generation. In order to satisfy the perpendicular magnetization condition, we replaced a part of Nd by Gd to decrease the saturation magnetization Ms and applied the multilayer (ML) structure to enhance the perpendicular anisotropy Ku. Then we succeeded in getting a new ML medium of Nd0.34Gd0.66/Fe0.9Co0.1 with a bilayer period of 1 nm. However, the substitution of 66% Gd resulted in undesirable decreases of Kerr rotation and coercivity. In this experiment, a part of Nd is replaced by either Tb or Dy instead of Gd with an expectation that the amount of replacement to get the perpendicular magnetization configuration may be smaller since Tb and Dy have large one ion anisotropy compared with Gd. The magnetic and MO properties of Nd(Tb,Dy)/FeCo MLs will be reported. In the case of Tb, for example, a square Kerr hysteresis loop is obtained by the substitution of about 40%. However, θK at 400 nm is about 0.30°, which is larger than that of Tb-FeCo but smaller than NdGd/FeCo MLs.

  2. 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

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

    SciTech Connect

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

    2009-12-14

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

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

    PubMed

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

    2015-06-15

    A family of 3d-4f [M(II)2Ln(III)2(μ3-OH)2(O2C(t)Bu)10](2-) "butterflies" (where M(II) = Mg, Co, Ni, and Cu; Ln(III) = Y, Gd, Tb, Dy, Ho, and Er) and [Mn(III)2Ln(III)2(μ3-O)2(O2C(t)Bu)10](2-) molecules (where Ln(III) = Y, Gd, Tb, Dy, Ho, and Er) has been synthesized and characterized through single-crystal X-ray diffraction, SQUID magnetometry, and ab initio calculations. All dysprosium- and some erbium-containing tetramers showed frequency-dependent maxima in the out-of-phase component of the susceptibility associated with slow relaxation of magnetization, and hence, they are single-molecule magnets (SMMs). AC susceptibility measurements have shown that the SMM behavior is entirely intrinsic to the Dy and Er sites and the magnitude of the energy barrier is influenced by the interactions between the 4f and the 3d metal. A trend is observed between the strength of the 3d-4f exchange interaction between and the maximum observed in the χ″M(T). PMID:26016421

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

    SciTech Connect

    Wang, H.; Yang, J.; Zhang, C.M.; Lin, J.

    2009-10-15

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

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

    SciTech Connect

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

    2015-05-14

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

  7. 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.

  8. 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.

  9. 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

  10. Spectroscopic characteristics of GdVO4: Dy3+ crystal

    NASA Astrophysics Data System (ADS)

    Ning, Kaijie; He, Xiaoming; Zhang, Lianhan; Liu, Youchen; Yin, Jigang; Zhang, Peixing; Chen, Guangzhu; Wang, Xiangyong; Chen, Zhe; Shi, Chunjun; Hong, Jiaqi; Hang, Yin

    2014-11-01

    Room temperature optical absorption, emission spectrum of GdVO4: Dy3+ crystal grown by Czochralski (CZ) method were measured and analyzed. Spectral parameters were calculated in the framework of the Judd-Ofelt theory. The GdVO4: Dy3+ crystal showed two intense and relatively broad absorption bands in UV wavelength range centered at 390 and 453 nm and two prominent emission peaks located at blue 485 and yellow 575 nm. The corresponding absorption and emission cross sections were estimated and the luminescence decay curve was analyzed. Optical spectroscopy investigations indicate that GdVO4: Dy3+ crystal would be a promising blue and yellow solid state laser material.

  11. 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.

  12. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  14. 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.

  15. Spectroscopic and energy transfer properties of Dy3+-doped, Tb3+/Dy3+-codoped dense oxyfluoride borogermanate scintillating glasses

    NASA Astrophysics Data System (ADS)

    Sun, Xin-Yuan; Yu, Xiao-Guang; Jiang, Da-Guo; Wang, Wen-Feng; Li, Yu-Nong; Chen, Zhi-Quan; Zhou, Yun-Zhi; Yang, Qing-Mei; Kang, Zhitao

    2016-06-01

    Dy3+-, Tb3+-activated, and Tb3+/Dy3+-coactivated oxyfluoride borogermanate scintillating glasses with the density of about 6.50 g/cm3 were successfully synthesized by a melt-quenching method. The structure and optical properties including transmittance, photoluminescence (excitation and emission spectra), photoluminescence decay, and X-ray excited luminescence (XEL) behaviors were studied in detail. Our results reveal that the energy transfer efficiency from Dy3+ to Tb3+ ions increases with an increase of Tb3+ concentration. The energy transfer mechanism is determined to be electric dipole-dipole interaction. However, the XEL intensity of Tb3+ decreases with the incorporation of sensitizer Dy3+ into borogermanate scintillating glass, which may result from the different mechanisms under ultraviolet light and X-ray excitation.

  16. Energy-transfer from Gd(III) to Tb(III) in (Gd,Yb,Tb)PO4 nanocrystals.

    PubMed

    Debasu, Mengistie L; Ananias, Duarte; Rocha, João; Malta, Oscar L; Carlos, Luís D

    2013-10-01

    The photoluminescence properties of (Gd,Yb,Tb)PO4 nanocrystals synthesized via a hydrothermal route at 150 °C are reported. Energy-transfer from Gd(3+) to Tb(3+) is witnessed by the detailed analyses of excited-state lifetimes, emission quantum yields, and emission and excitation spectra at room temperature, for Tb(3+) concentrations ranging from 0.5 to 5.0 mol%. Absolute-emission quantum yields up to 42% are obtained by exciting within the (6)I7/2-17/2 (Gd(3+)) manifold at 272 nm. The room temperature emission spectrum is dominated by the (5)D4 → (7)F5 (Tb(3+)) transition at 543 nm, with a long decay-time (3.95-6.25 ms) and exhibiting a rise-time component. The (5)D3 → (7)F6 (Tb(3+)) rise-time (0.078 ms) and the (6)P7/2 → (8)S7/2 (Gd(3+)) decay-time (0.103 ms) are of the same order, supporting the Gd(3+) to Tb(3+) energy-transfer process. A remarkably longer lifetime of 2.29 ms was measured at 11 K for the (6)P7/2 → (8)S7/2 (Gd(3+)) emission upon excitation at 272 nm, while the emission spectrum at 11 K is dominated by the (6)P7/2 → (8)S7/2 transition line, showing that the Gd(3+) to Tb(3+) energy-transfer process is mainly phonon-assisted with an efficiency of ~95% at room temperature. The Gd(3+) to Tb(3+) energy transfer is governed by the exchange mechanism with rates between 10(2) and 10(3) s(-1), depending on the energy mismatch conditions between the (6)I7/2 and (6)P7/2 levels of Gd(3+) and the Tb(3+ 5)I7, (5)F2,3 and (5)H5,6,7 manifolds and the radial overlap integral values. PMID:23942992

  17. 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.

  18. 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.

  19. Microscopic mechanistic study on the multiferroic of R2CoMnO6/La2CoMnO6 (R = Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm) by chemical and hydrostatic pressures: a first-principles calculation.

    PubMed

    Meng, Junling; Liu, Xiaojuan; Hao, Xianfeng; Zhang, Lifang; Yao, Fen; Meng, Jian; Zhang, Hongjie

    2016-09-14

    A specific class of multiferroic superlattices R2CoMnO6/La2CoMnO6 (R = Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm), which displayed observable electric polarizations and considerable magnetization, were investigated based on density functional theory. The multiferroic behavior was induced by both of the a(-)a(-)c(+) Glazer rotation patterns of BO6 (CoO6 and MnO6) octahedra and ferromagnetic coupling in the magnetic ordered superlattices. In addition, the ferroelectric and ferromagnetic properties of R2CoMnO6/La2CoMnO6 superlattices can be tuned by chemical pressure and hydrostatic pressure, with the former being more effective in tuning magnetoelectric properties than the latter. For chemical pressure, the incorporation of lanthanide ions promoted an increase of BO6 octahedral tilting, reflected by the sharp decrease of Co-O3-Mn bond angles in the R-layer along the c axis. By contrast, the hydrostatic pressure acts on all three directions of the superlattice so that the change in Co-O-Mn bond angles is relatively small, therefore the octahedral distortion is much smaller than that caused by chemical pressure. Consequently, the electric polarization and magnetization changed more slowly. Our first-principles simulations proposed a series of rational multiferroic superlattices with tunable ferromagnetism and ferroelectricity by chemical and hydrostatic pressures, with expectation to be applied as novel spintronic materials. PMID:27506617

  20. 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.

  1. 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.

  2. 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.

  3. Electronic structure, magnetism, and Fermi surfaces of Gd and Tb

    NASA Astrophysics Data System (ADS)

    Ahuja, R.; Auluck, S.; Johansson, B.; Brooks, M. S. S.

    1994-08-01

    We report on local-spin-density calculations for the ferromagnetic rare-earth metals Gd and Tb using the relativistic first-principles linear-muffin-tin-orbital method in the atomic-sphere approximation. We have used a method which treats simultaneously the localized 4f and the conduction-electron spin magnetism. The 4f magnetic moments are obtained from the Russel-Saunders scheme but the radial 4f spin density is a part of the self-consistent density-functional calculations. The calculated conduction-electron moment for Gd is in very good agreement with the measured value. The calculated de Haas-von Alphen frequencies are in agreement with available data.

  4. 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.

  5. High-pressure synthesis of a La orthosilicate and Nd, Gd, and Dy disilicates

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoyang; Fleet, Michael E.

    2002-11-01

    Several rare-earth silicates have been synthesized at 10 GPa and 1600-1700 °C: a La orthosilicate (La4Si3O12) with a defect Ba3(PO4)2-type, a new structure type (K) for Nd and Gd disilicates (Nd2Si2O7 and Gd2Si2O7) with a diorthosilicate structure, and a new structure type (L) for Dy disilicate (Dy2Si2O7) with a structure containing linear triple tetrahedral groups [Si3O10], but having one in six atoms distributed with 50% occupancy over two tetrahedral positions.

  6. Perpendicular Magnetic Anisotropy of Tb/Fe and Gd/Fe Multilayers Studied with Torque Magnetometer

    NASA Astrophysics Data System (ADS)

    Chowdhury, Ataur

    Perpendicular magnetic anisotropy (PMA) of multilayers critically depend on the magnetic and structural ordering of the interface. To study the effect of interface on PMA, Tb/Fe and Gd/Fe multilayers with varying Fe (0.8-9.0 nm) and Gd (0.5-2.8 nm) or Tb (0.3-6.3 nm) layer thicknesses were fabricated by planar magnetron sputtering. The magnetometer results of spin orientation clearly reveals that samples with Gd or Tb layer thickness of more than 1.2 nm display no PMA, regardless of the Fe layer thickness. Tb/Fe and Gd/Fe multilayers with thin (<1.2 nm) Tb or Gd layers display large PMA, but no PMA is observed when the Fe layer thickness is increased to 4.0 nm and higher. The bulk magnetization and anisotropy energy constant of the samples are found to increase with increasing Fe layer thickness. Torque measurement also reveals that there are two distinctly different axes of spin alignment at different energy. Tb/Fe and Gd/Fe multilayers with similar composition reveal similar magnetic and structural characteristics, and it may imply that single-ion-anisotropy of rare-earth element, which is quite large for Tb ions and very small for Gd ions, may not be the dominating cause of PMA in Td/Fe and Gd/Fe multilayers. A detailed explanation of the results will be provided based on exchange interaction at the interface.

  7. 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

  8. 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.

  9. Photoluminescence Properties and Energy Transfer in a Novel Yellow Emitting Phosphor GdTaO4: Dy3+.

    PubMed

    Zhang, Hijuan; Tan, Xinyu; Wang, Yuhua

    2016-04-01

    The phosphor Dy3+ doped M type gadolinium orthotantalate GdTaO4 was prepared successfully by traditional solid state reaction and the photoluminescence of GdTaO4: xDy3+ (0.01 ≤ x ≤ 0.10) has been investigated under ultraviolet and vacuum ultraviolet excitation. In the excitation spectra of GdTaO4: Dy3+, the overlap appears between the host lattice excitation, the excitation lines of Gd3+ and the f-f transitions of Dy3+, which indicates that the energy transfer could occur from the host to the Dy3+ ions. In the emission spectra of the samples, the intense emissions of Dy3+ have been expectably revealed both upon excitation at 365 nm and 147 nm. And the chromaticity coordinates of GdTaO4: xDy3+ have been correspondingly calculated. The results indicate that GdTaO4: Dy3+ would be a novel yellow emitting phosphor applied in light emitting diodes (LEDs), plasma display panels (PDPs) and mercury-free fluorescent tubes. PMID:27451754

  10. 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

  11. Investigation on the magnetocaloric effect in RNi2 (R: Dy, tb) melt-spun ribbon

    NASA Astrophysics Data System (ADS)

    de Souza, M. V.

    2016-08-01

    We report a theoretical and experimental investigation on the magnetocaloric properties of the rare earth RNi2 (R=Dy,Tb) in melt-spun ribbon and bulk form. The theoretical calculations were performed using a Hamiltonian model including the Zeeman-exchange interactions and the crystalline electrical field. Thus the magnetocaloric potential was calculated in the easy magnetic axes, in order an average over all of the possible directions. The isothermal entropy-change dependence on temperature calculated was compared with available experimental data for melt-spun ribbon and bulk material. We also investigated, theoretically and experimentally, the behavior of a DyNi2 and TbNi2 composite with optimized molar proportions and discussed this in the context of the optimum regeneration Ericsson cycle.

  12. Visible quantum cutting through downconversion in GdPO{sub 4}:Tb{sup 3+} and Sr{sub 3}Gd(PO{sub 4}){sub 3}:Tb{sup 3+}

    SciTech Connect

    Wang Deyin; Kodama, Nobuhiro

    2009-08-15

    Visible quantum cutting has been observed in GdPO{sub 4}:Tb{sup 3+} upon Tb{sup 3+} 4f{sup 8}-4f{sup 7}5d{sup 1} excitation and host excitation, and in Sr{sub 3}Gd(PO{sub 4}){sub 3}:Tb{sup 3+} upon Tb{sup 3+} 4f{sup 8}-4f{sup 7}5d{sup 1} excitation. In the quantum cutting process, Tb{sup 3+} acts as a quantum cutter, which converts one short wavelength ultraviolet photon or one vacuum ultraviolet photon into more than one visible photon. The quantum cutting involves a cross-relaxation process between two neighboring Tb{sup 3+} and direct energy transfer between Tb{sup 3+} and Tb{sup 3+} or Tb{sup 3+} and Gd{sup 3+}, depending on the excitation wavelength. The quantum efficiency variation of GdPO{sub 4}:xTb{sup 3+} and Sr{sub 3}Gd(PO{sub 4}){sub 3}:xTb{sup 3+} shows a growing trend with increasing of Tb{sup 3+} content from x=1.5% to 13%. - Graphical abstract: The ratio of emission from {sup 5}D{sub 4} level to that attributed to {sup 5}D{sub 3} of Tb{sup 3+} and {sup 6}P{sub J} of Gd{sup 3+} under 210,196 and 157 nm excitations are much stronger than that under 273 nm excitation, indicating visible quantum cutting has occurred in GdPO{sub 4}:Tb{sup 3+} upon Tb{sup 3+} 4f{sup 8}-4f{sup 7}5d{sup 1} excitation and host excitation.

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

    PubMed

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

    2014-03-01

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

  14. 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

  15. Fabrication and properties of Nd(Tb,Dy)Co/Cr films with perpendicular magnetic anisotropy

    NASA Astrophysics Data System (ADS)

    Cheng, Weiming; Miao, Xiangshui; Yan, Junbing; Cheng, Xiaomin

    2009-08-01

    Light rare earth-heavy rare earth-transition metal films (LRE-HRE-TM)have large saturation magnetization (Ms) and are the promising media for hybrid recording. In this paper, Nd(Tb,Dy)Co/Cr films with perpendicular magnetic anisotropy were successfully fabricated onto glass substrate by RF magnetron sputtering and the effects of sputtering technology parameters and Nd substitution for HRE atoms on the magnetic properties were investigated. It was found that when the sputtering power and sputtering time are 250W and 4min, respectively, the magnetic properties of Nd(Tb,Dy)Co/Cr films obtain optimization, perpendicular coercivity, Ms and remanence square ratio(S) of NdTbCo/Cr film reach 3.8kOe, 247emu/cm3 and 0.801, respectively. With the increasing of Nd concentration, Ms increases, while the coercivity (Hc)and the temperature stability of magnetic properties decrease distinctly. These results can be explained by the ferri-magnetic structure of the RE-TM alloy.

  16. Formation of bcc non-equilibrium La, Gd, and Dy alloys and the magnetic structure of Mg-stabilized. beta. Gd and. beta. Dy

    SciTech Connect

    Herchenroeder, J.W.

    1988-01-01

    The high temperature bcc allotrope of a rare earth metal has the potential for substantially different magnetic properties than the room temperature hexagonal (hcp or dcp) counterpart because of its more symmetrical crystal field. The stabilization by alloying and quenching of this bcc phase was studied for La-M alloys where M is a non-rare earth metal from Group II or III. The factors influencing the stabilization, such as size of M and quench rate, are discussed. {gamma}La (bcc) could be retained over a composition range around the eutectoid composition by Mg or Cd alloying. A comparison of T{sub o} curves of the various alloy systems suggest that the eutectoid temperature of the La-M system must be approximately equal to or less than a critical T{sub o} temperature of 515{degree}C if the bcc phase is to be retained by quenching. The thermal stability of {beta}Gd (bcc) was investigated by DTA and isothermal annealing. It was found to transform to an intermediate phase before reverting to the equilibrium phases in contrast to {gamma}La alloys which decompose directly on heating to the equilibrium phases. Bcc {beta}Gd and {beta}Dy stabilized by Mg additions exhibit spin glass-like behavior. Both systems show field cooling effects in the magnetic susceptibility which is indicative of spin freezing reactions.

  17. Intensive emission of Dy3+ in NaGd(PO3)4 for Hg-free lamps application.

    PubMed

    Zhong, Jiuping; Liang, Hongbin; Han, Bing; Tian, Zifeng; Su, Qiang; Tao, Ye

    2008-05-12

    The phosphor NaGd(PO(3))(4):Dy(3+) was synthesized by solid-state reaction technique at high temperature. The vacuum ultraviolet (VUV)-UV excitation spectra and visible emission spectra under VUV/UV excitation were investigated. The sample NaGd(PO(3))(4):Dy(3+) showed suitable spectroscopic characteristics such as broad and strong absorption around 172 nm, intensive emission with the chromaticity coordinates (0.33, 0.38) in warm-white light region. Additionally, this efficient white-emitting phosphor is activated by a single Dy(3+) ion and with a lower preparation temperature, which tend to decrease the consumption of rare earth resource and energy. Therefore, the phosphor NGP:Dy(3+) may be considered as a suitable candidate for Hg-free lamps application. PMID:18545456

  18. 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.

  19. Photoluminescence and energy transfer process in Gd2O3:Eu3+, Tb3+

    NASA Astrophysics Data System (ADS)

    Selvalakshmi, T.; Bose, A. Chandra

    2016-05-01

    Variation in photoluminescence (PL) properties of Eu3+ and Tb3+ as a function of co-dopant (Tb3+) concentration are studied for Gd2-x-yO3: Eu3+x Tb3+y (x = 0.02, y = 0.01, 0.03, 0.05). The crystal structure analysis is carried out by X-ray Diffraction (XRD). Absence of addition peaks corresponding europium or terbium phase confirms the phase purity. Diffuse reflectance spectroscopy (DRS) reveals the absorption peaks corresponding to host matrix, Eu3+ and Tb3+. The bandgap calculated from Kubelka - Munk function is also reported. PL spectra are recorded at the excitation wavelength of 307 nm and the emission peak corresponding to Eu3+ confirms the energy transfer from Tb3+ to Eu3+. The agglomeration of particles acts as quenching centres for energy transfer at higher concentrations.

  20. Investigation on photoluminescence properties and defect chemistry of GdAlO3:Dy3+ Ba2+ phosphors

    NASA Astrophysics Data System (ADS)

    Selvalakshmi, Thangaraj; Sellaiyan, Selvakumar; Uedono, Akira; Semba, Takaaki; Bose, Arumugam Chandra

    2016-08-01

    GdAlO3:Dy3+ Ba2+ phosphors are synthesized by citrate-based sol-gel method. Photoluminescence and positron annihilation studies are used to investigate the emission and defect chemistry of the phosphors respectively. The strong yellow (Dy3+) emission properties of phosphors are discussed for various concentrations of Dy3+ ions. Upon the addition of Ba2+ ion, an enhancement in emission intensity is observed due to the lattice distortions around Dy3+ ion. The positron studies indicate the presence of defects at crystallite boundaries, vacancy clusters and large voids in the materials. The influence of Ba2+ ion on the photoluminescence and lattice distortion around Dy3+ is also explored.

  1. TM dependence of the magneto-optic signal in GdTb-TM thin films

    SciTech Connect

    Hairston, D.K.; Kryder, M.H.

    1988-04-15

    The magneto-optic polar Kerr rotation for various GdTb-TM thin films was measured at room temperature as a function of TM composition and was found to correlate with the Slater--Pauling curve. In spite of the fact that the temperature dependence of magnetization is a complicating factor, the data clearly establish the above-mentioned correlation. The TM compositions ranged from Mn through Fe and Co to Ni. The Fe-based films had Curie temperatures covering a range from 100 to 300 /sup 0/C in contrast to the Co-based films whose Curie temperatures were clearly much greater than 300 /sup 0/C. Neither the Mn- nor the Ni-based films exhibited desirable magneto-optic activity when fabricated under the same conditions as the Fe- and/or Co-based films. When the Fe constituent of the GdTbFe films was gradually substituted with Mn or Co the room-temperature magneto-optic signal was found to decrease and increase, respectively. In a similar manner, when the Co constituent of GdTbCo films was gradually substituted with Fe or Ni the room-temperature magneto-optic effect was found to increase and decrease, respectively. However, when the Co constituent of GdTbCo films was gradually substituted with Mn the room-temperature magneto-optic effect also decreased, clearly establishing the correlation to the Slater--Pauling curve. These results are further evidence that the magneto-optic effect of traditional RE-TM thin films is dominated by the TM composition and explain the fact that the magneto-optic signal is largest in GdTbFeCo thin films. New data supporting the correlation between magneto-optic effect and perpendicular anisotropy was also obtained.

  2. Transparent ferromagnetic and semiconducting behavior in Fe-Dy-Tb based amorphous oxide films

    PubMed Central

    Taz, H.; Sakthivel, T.; Yamoah, N. K.; Carr, C.; Kumar, D.; Seal, S.; Kalyanaraman, R.

    2016-01-01

    We report a class of amorphous thin film material comprising of transition (Fe) and Lanthanide metals (Dy and Tb) that show unique combination of functional properties. Films were deposited with different atomic weight ratio (R) of Fe to Lanthanide (Dy + Tb) using electron beam co-evaporation at room temperature. The films were found to be amorphous, with grazing incidence x-ray diffraction and x-ray photoelectron spectroscopy studies indicating that the films were largely oxidized with a majority of the metal being in higher oxidation states. Films with R = 0.6 were semiconducting with visible light transmission due to a direct optical band-gap (2.49 eV), had low resistivity and sheet resistance (7.15 × 10−4 Ω-cm and ~200 Ω/sq respectively), and showed room temperature ferromagnetism. A metal to semiconductor transition with composition (for R < 11.9) also correlated well with the absence of any metallic Fe0 oxidation state in the R = 0.6 case as well as a significantly higher fraction of oxidized Dy. The combination of amorphous microstructure and room temperature electronic and magnetic properties could lead to the use of the material in multiple applications, including as a transparent conductor, active material in thin film transistors for display devices, and in spin-dependent electronics. PMID:27298196

  3. Transparent ferromagnetic and semiconducting behavior in Fe-Dy-Tb based amorphous oxide films

    NASA Astrophysics Data System (ADS)

    Taz, H.; Sakthivel, T.; Yamoah, N. K.; Carr, C.; Kumar, D.; Seal, S.; Kalyanaraman, R.

    2016-06-01

    We report a class of amorphous thin film material comprising of transition (Fe) and Lanthanide metals (Dy and Tb) that show unique combination of functional properties. Films were deposited with different atomic weight ratio (R) of Fe to Lanthanide (Dy + Tb) using electron beam co-evaporation at room temperature. The films were found to be amorphous, with grazing incidence x-ray diffraction and x-ray photoelectron spectroscopy studies indicating that the films were largely oxidized with a majority of the metal being in higher oxidation states. Films with R = 0.6 were semiconducting with visible light transmission due to a direct optical band-gap (2.49 eV), had low resistivity and sheet resistance (7.15 × 10‑4 Ω-cm and ~200 Ω/sq respectively), and showed room temperature ferromagnetism. A metal to semiconductor transition with composition (for R < 11.9) also correlated well with the absence of any metallic Fe0 oxidation state in the R = 0.6 case as well as a significantly higher fraction of oxidized Dy. The combination of amorphous microstructure and room temperature electronic and magnetic properties could lead to the use of the material in multiple applications, including as a transparent conductor, active material in thin film transistors for display devices, and in spin-dependent electronics.

  4. Transparent ferromagnetic and semiconducting behavior in Fe-Dy-Tb based amorphous oxide films.

    PubMed

    Taz, H; Sakthivel, T; Yamoah, N K; Carr, C; Kumar, D; Seal, S; Kalyanaraman, R

    2016-01-01

    We report a class of amorphous thin film material comprising of transition (Fe) and Lanthanide metals (Dy and Tb) that show unique combination of functional properties. Films were deposited with different atomic weight ratio (R) of Fe to Lanthanide (Dy + Tb) using electron beam co-evaporation at room temperature. The films were found to be amorphous, with grazing incidence x-ray diffraction and x-ray photoelectron spectroscopy studies indicating that the films were largely oxidized with a majority of the metal being in higher oxidation states. Films with R = 0.6 were semiconducting with visible light transmission due to a direct optical band-gap (2.49 eV), had low resistivity and sheet resistance (7.15 × 10(-4) Ω-cm and ~200 Ω/sq respectively), and showed room temperature ferromagnetism. A metal to semiconductor transition with composition (for R < 11.9) also correlated well with the absence of any metallic Fe(0) oxidation state in the R = 0.6 case as well as a significantly higher fraction of oxidized Dy. The combination of amorphous microstructure and room temperature electronic and magnetic properties could lead to the use of the material in multiple applications, including as a transparent conductor, active material in thin film transistors for display devices, and in spin-dependent electronics. PMID:27298196

  5. Increase in the Tb3+ green emission in SiO2-LaF3 nano-glass-ceramics by codoping with Dy3+ ions

    NASA Astrophysics Data System (ADS)

    Velázquez, J. J.; Rodríguez, V. D.; Yanes, A. C.; del-Castillo, J.; Méndez-Ramos, J.

    2010-12-01

    95SiO2-5LaF3 sol-gel derived nano-glass-ceramics single doped with 0.1Dy3+ or 0.1Tb3+ mol % and codoped with 0.1Dy3+ and xTb3+ (x=0.1,0.3) mol % were successfully obtained. XRD and HRTEM measurements confirm the precipitation of LaF3 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 LaF3 nanocrystals, as calculated from luminescence decays. The effect of increasing the Tb3+ concentration and also of codoping with Dy3+ in the Tb3+ green emission from the D54 level have been studied. The energy transfer mechanisms between Tb3+ ions and also between Tb3+-Dy3+ ions, which favor the green emission, have been analyzed.

  6. 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.

  7. 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

  8. Synthesis, modified optical properties, and energy transfer of Tb3+ doped GdF3

    NASA Astrophysics Data System (ADS)

    Cao, Chunyan; Guo, Siling; Kee Moon, Byung; Chun Choi, Byung; Hyun Jeong, Jung

    2013-08-01

    By controlling the volume of HF and the alkaline earth ion introducing, a series of GdF3 samples have been synthesized by a hydrothermal method without any surfactant. The samples are characterized by X-ray diffraction (XRD) patterns, field emission scanning electron microscopy (FE-SEM) images, energy-dispersive spectroscopy (EDS) spectra, photoluminescence (PL) excitation and emission spectra as well as the luminescence dynamic decay curves. The optical properties of Tb3+ and the energy transfer from host Gd3+ to Tb3+ have been investigated and discussed in detail based on the volume of HF used in the synthesis procedure and the alkaline earth ion introducing. The experimental results suggest that the optical properties of Tb3+ can be controlled by the deliberately ion introducing as well as the volume of HF used in the synthesis procedure. Though the optical properties of Tb3+ can be adjusted by different ways, a green, easy, and cost saving way, such as deliberately ion introducing, is a good choice in modifying the optical properties of Tb3+.

  9. 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.

  10. Enhanced magnetoelastic effect in Laves (Tb,Dy)Fe2 alloys with the joint introduction of Pr and Nd

    NASA Astrophysics Data System (ADS)

    Song, X. H.; Liu, J. J.; Wei, S. H.; Zhu, X. Y.; Li, F.; Zhang, Z. R.; Si, P. Z.; Ren, W. J.

    2016-06-01

    The structural and magnetoelastic properties of (Tb0.3Dy0.7)1-x(Pr0.5Nd0.5)xFe1.93 (0 ≤ x ≤ 0.20) polycrystalline alloys have been investigated by means of X-ray diffraction (XRD), a vibrating sample magnetometer and a standard strain gauge technique. A single (Tb,Dy,Pr,Nd)Fe2 Laves phase with a cubic MgCu2-type structure is formed when x ≤ 0.12, while a small amount of impurities appear when x ≥ 0.15. The easy magnetization direction at room temperature is detected toward <111> axis. The analysis of XRD, magnetization and magnetostriction shows that the Pr and Nd elements joint introduction into (Tb,Dy)Fe2 system can reduce the magnetocrystalline anisotropy and improve the magnetoelastic properties. The (Tb0.3Dy0.7)0.88(Pr0.5Nd0.5)0.12Fe1.93 alloy exhibits a high low-field magnetostriction λ a (~314 ppm/1 kOe), a large spontaneous magnetostriction coefficient λ 111 (~1710 ppm), a giant saturation magnetostriction λ S (~1060 ppm) and the low magnetocrystalline anisotropy at room temperature, and may make it a promising candidate for magnetostriction applications.

  11. Cooperative energy transfer and frequency upconversion in Yb3+-Tb 3+ and Nd 3+-Yb 3+-Tb 3+ codoped GdAl3(BO3)4 phosphors.

    PubMed

    Yang, C H; Pan, Y X; Zhang, Q Y; Jiang, Z H

    2007-09-01

    Polycrystalline GdAl(3)(BO(3))(4) phosphors co-doped with Yb(3+)/Tb(3+) and/or Nd(3+)/Yb(3+)/Tb(3+) have been synthesized by combustion method. Upon excitation with a 980 nm laser diode, an intense green upconversion luminescence has been observed in GdAl(3)(BO(3))(4):Yb,Tb phosphor. The quadratic dependence of the luminescence on the pump-laser power indicating a cooperative energy transfer process. Meanwhile, it is noticed that upon excitation with 808 nm laser diode, intense luminescence has clearly been detected in GdAl(3)(BO(3))(4):Nd,Yb,Tb phosphor. The luminescence intensity exhibits also a quadratic dependence on incident pump-laser power. However, no green-emission has been observed in GdAl(3)(BO(3))(4) phosphors co-doped with Yb(3+)/Tb(3+) or Nd(3+)/Tb(3+) respectively upon excited at 808 nm laser diode. A proposed upconversion mechanism involving energy transfer from Nd(3+) to Yb(3+), and then a cooperative energy transfer process from two excited Yb(3+) to Tb(3+) has been presented. PMID:17609865

  12. 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}.

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

    DOE PAGESBeta

    Tschauner, Oliver; Ushakov, Sergey V.; Navrotsky, Alexandra; Boatner, Lynn A.

    2016-01-06

    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. 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. We show softening of (c1133 + c1313) combined elastic moduli close to the transition from the anhydrite to the monazite structure. Stress response of rare-earth orthophosphate ceramics can be affected by both formation of the anhydrite-typemore » phase and the elastic softening in the vicinity of the monazite-phase. In conclusion, we report the first structural data for an anhydrite-type rare earth orthophosphate.« less

  14. 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.

  15. 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.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

  18. 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

  19. 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.

  20. Magnetostrictive gradient in Tb0.27Dy0.73Fe1.95 induced by high magnetic field gradient applied during solidification

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    We investigated how high magnetic field gradients affected the magnetostrictive performance of Tb0.27Dy0.73Fe1.95 during solidification. At high applied magnetic field gradients, the magnetostriction exhibited a gradient distribution throughout the alloy. Increasing the magnetic field gradient also increased the magnetostriction gradient. We attributed the graded magnetostrictive performance to the gradient distribution of (Tb, Dy)Fe2 phase in the alloy and its orientation.

  1. Incoherent scattering of 137Cs gamma rays in the rare earth elements Nd, Sm, Gd, Dy, Er and Yb

    NASA Astrophysics Data System (ADS)

    Krishnaveni, S.; Gowda, Shivalinge; Yashoda, T.; Umesh, T. K.; Gowda, Ramakrishna

    2005-09-01

    The differential incoherent scattering cross sections for 661.6 keV photons have been measured with an HPGe detector in the momentum range 4⩽x⩽46 Å-1 for the rare earth elements Nd, Sm, Gd, Dy, Er and Yb. The incoherent scattering functions were evaluated from the measured cross sections and compared with the NRHF values of Hubbel et al. [1975, J. Phys. Chem. Ref. Data 4, 471], the recent DHFR values of Kahane [1998, At. Data Nucl. Data Tables 68, 323] and other measured values. The present experimental values are systematically lower than the theoretical predictions, but show a good agreement within the experimental errors except for the momentum transfers of 30.59, 34.29 and 37.72 Å -1 for Nd, 43.69 Å -1 for Gd and 22.54 and 26.66 Å -1 for Dy, which show deviations at the two sigma level.

  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. 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.

  4. Structural and magnetic phase transitions in TbRuAsO and DyRuAsO

    NASA Astrophysics Data System (ADS)

    McGuire, Michael; May, Andrew; Garlea, Ovidiu; Sales, Brian

    2013-03-01

    The compounds LnRuAsO (Ln = lanthanide) are isoelectronic, isostructural, 4 d transition metal analogues of the parent phases of 1111-type iron superconductors, but display markedly different behaviors. Recent results from crystallographic and physical properties measurements on TbRuAsO and DyRuAsO reveal particularly unusual properties in these materials. Analysis of low temperature x-ray and neutron powder diffraction data indicate a symmetry-lowering crystallographic phase transition in DyRuAsO at 25 K, and ordering of rare-earth magnetic moments at 7.0 and 10.5 K for TbRuAsO and DyRuAsO, respectively. The structural distortion observed in DyRuAsO (to space group Pmmn) is different than the well-known distortion that occurs in LnFeAsO. In addition, the findings indicate some coupling between the magnetism and the lattice, and hints of Ru magnetism are observed. A response to the structural transition is apparent in the magnetic susceptibility, and the associated heat capacity anomaly responds strongly to a magnetic field. Research supported by the US Department of Energy, Basic Energy Sciences, Materials Sciences and Engineering Division (synthesis, physical and structural properties), and Scientific User Facilities Division (neutron diffraction, HB2A high-resolution powde

  5. 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.

  6. 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.

  7. Rare Earth Dopant (Nd, Gd, Dy, and Er) Hybridization in Lithium Tetraborate

    NASA Astrophysics Data System (ADS)

    Kelly, Tony; Petrosky, James; McClory, John; Adamiv, Volodymyr; Burak, Yaroslav; Padlyak, Bohdan; Teslyuk, Ihor; Lu, Ning; Wang, Lu; Mei, Wai-Ning; Dowben, Peter

    2014-05-01

    The four dopants (Nd, Gd, Dy, and Er) substitutionally occupy the Li+ sites in lithium tetraborate (Li2B4O7: RE) glasses as determined by analysis of the extended X-ray absorption fine structure. The dopants are coordinated by 6-8 oxygen at a distance of 2.3 to 2.5 Å, depending on the rare earth. The inverse relationship between the RE¬ O coordination distance and rare earth (RE) atomic number is consistent with the expected lanthanide atomic radial contraction with increased atomic number. Through analysis of the X-ray absorption near edge structure, the rare earth dopants adopt the RE3+ valence state. There are indications of strong rare earth 5d hybridization with the trigonal and tetrahedral formations of BO3 and BO4 based on the determination of the rare earth substitutional Li+ site occupancy from the X-ray absorption near edge structure data. The local oxygen disorder around the RE3+ luminescence centers evident in the structural determination of the various glasses, and the hybridization of the RE3+ dopants with the host may contribute to the asymmetry evident in the luminescence emission spectral lines. The luminescence emission spectra are indeed characteristic of the expected f-to-f transitions; however, there is an observed asymmetry in some emission lines.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  9. Electrical and thermal properties of Tb0.3Dy0.7Fe2-x

    NASA Astrophysics Data System (ADS)

    Cook, B. A.; Harringa, J. L.; Hansen, T.

    2000-01-01

    Samples of Tb0.3Dy0.7Fe2-x where x=0.05-0.10 (TERFENOL-D) were characterized for electrical resistivity and thermal diffusivity between room temperature and the Curie temperature, which for this composition is 360 °C. Additionally, the thermal diffusivity of one of the samples was measured to 1000 °C. Measurements were performed on two different orientations of standard, production-grade, grain-oriented TERFENOL-D produced by a Bridgman growth technique at ETREMA Products, Inc. The orientations were parallel and normal to the <112> crystallographic direction. The electrical resistivity and thermal diffusivity both exhibited isotropic behavior over the temperature range studied. The electrical resistivity of all samples increased monotonically from 0.06 mΩ-cm at room temperature to 0.14 mΩ cm at 360 °C, consistent with behavior expected for normal metals. The thermal conductivity was found to decrease with temperature from 135 mW/cm °C at room temperature to 122 mW/cm °C at 360 °C. The thermal diffusivity was found to exhibit a sharp cusp in the vicinity of the Curie temperature, TC, increasing with temperature for T>TC. Application of the Wiedemann-Franz law indicates that over 86% of the heat is carried by electrons.

  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. 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.

  12. M (Tm3+, Tb3+, Ho3+, Dy3+, Mn2+)-doped transparent fluorophosphate glasses for white light-emitting-diodes

    NASA Astrophysics Data System (ADS)

    Ming, Chengguo; Song, Feng; Qin, Yueting; Ren, Xiaobin; An, Liqun

    2014-06-01

    M-doped (M=Tm3+, Tb3+, Ho3+, Dy3+, Mn2+) transparent fluorophosphate glasses were prepared by a high temperature melting method. Excitation and emission spectra of the samples were investigated. Under near-ultraviolet excitation, the emission colors of the Tm3+-and Mn2+-doped samples are blue and red, respectively; the emission colors of the Tb3+-, Ho3+-, and Dy3+-doped samples are green; and the emission color of Tb3+/ Mn2+/Tm3+ tridoped fluorophosphate glass is white to the naked eye. Our research will be helpful in developing luminescent materials for white light-emitting-diodes.

  13. 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

  14. Photoluminescence of Tb 3+ and Mn 2+ activated Ca 8MgGd(PO 4) 7 under vacuum ultraviolet excitation

    NASA Astrophysics Data System (ADS)

    Zhang, Jia; Wang, Yuhua; Huang, Yan

    2011-06-01

    Novel Tb 3+ and Mn 2+ activated Ca 8MgGd(PO 4) 7 phosphors were synthesized by solid-state reaction and their photoluminescence properties in vacuum ultraviolet region were investigated for the first time. It can be observed from the excitation spectra that the host-related absorption band is located around 170 nm, and it overlaps the O 2- → Tb 3+ charge transfer band of Ca 8MgGd(PO 4) 7:Tb 3+ around 161 nm and the 3d 5 → 3d 44s transition band of Ca 8MgGd(PO 4) 7:Mn 2+ near 200 nm. The 4f-4f 5d spin-allowed and spin-forbidden transitions of Tb 3+ are verified to be located at 170-250 and 257-271 nm, respectively. Upon 147 nm excitation, the dominant emission peak intensity of the Ca 8MgGd 0.1(PO 4) 7:0.9Tb 3+ phosphor is about 2.7 times stronger than that of the commercial Zn 2SiO 4:Mn 2+ green phosphor, and the brightness of the former with a short decay time of 2.5 ms is about 98% of the latter's. The Ca 8MgGd(PO 4):Mn 2+ phosphor excited at 147 nm exhibits a deep red emission around 650 nm, which could be attributed to the 4T 1 → 6A 1 transition of Mn 2+, with the CIE index (0.679, 0.321). In a word, the results above indicate that both Tb 3+ and Mn 2+ activated Ca 8MgGd(PO 4) 7 phosphors could be promising for PDP or Hg-free lamp applications.

  15. 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

  16. 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.

  17. Synthesis and Photoluminescence Characteristics of CaIn2O4:Dy3+ Phosphors Co-Doped with Gd3+, Zn2+ or AI3+ Ions.

    PubMed

    Gou, Jing; Wang, Jing; Yu, Binxun; Zhang, Dongyang

    2016-04-01

    Novel warm-white emitting phosphors CaIn2O4:Dy3+ co-doped with Gd3+, Zn2+, or Al3+ ions were prepared by solid state reaction. In this paper, a strategy of co-doping with different ions was used with the aim of affecting the luminescence properties of CaIn204:0.6%Dy3+ under NUV excitation. The luminescence intensities of CaIn2O4:0.6%Dy3+ were enhanced by 0.2% Gd3+ or 0.2% Zn2+ ions co-doping under 367 nm excitation, but lowered by co-doping with 0.2% Al3+ ions. Furthermore, the chromaticity coordinates of CaIn2O4:0.6%Dy3+ can be tuned from the cold-white region to warm-white region with Gd3+ or Zn2+ ions co-doping. These findings show that CaIn2O4:0.6%Dy3+,0.2% Gd3+, and CaIn2O4:0.6%Dy3+,0.2% Zn2+ have potential application value as new warm-white LED phosphors. PMID:27451749

  18. 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

  19. 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.

  20. Heterometallic trinuclear {CoLn(III)} (Ln = Gd, Tb, Ho and Er) complexes in a bent geometry. Field-induced single-ion magnetic behavior of the Er(III) and Tb(III) analogues.

    PubMed

    Goura, Joydeb; Brambleby, Jamie; Topping, Craig V; Goddard, Paul A; Suriya Narayanan, Ramakirushnan; Bar, Arun Kumar; Chandrasekhar, Vadapalli

    2016-05-31

    Through the use of a multi-site compartmental ligand, 2-methoxy-6-[{2-(2-hydroxyethylamino)ethylimino}methyl]phenol (LH3), the family of heterometallic, trinuclear complexes of the formula [CoLn(L)2(μ-O2CCH3)2(H2O)3]·NO3·xMeOH·yH2O has been expanded beyond Ln = Dy(III) to include Gd(III) (), Tb(III) (), Ho(III) () and Er(III) () for , and (x = 1; y = 1) and for (x = 0; y = 2). The metallic core of these complexes consists of a (Co(III)-Ln(III)-Co(III)) motif bridged in a bent geometry resulting in six-coordinated distorted Co(III) octahedra and nine-coordinated Ln(III) monocapped square-antiprisms. The magnetic characterization of these compounds reveals the erbium and terbium analogues to display a field induced single-ion magnetic behavior similar to the dysprosium analogue but at lower temperatures. The energy barrier for the reversal of the magnetization of the CoTb(III) analogue is Ueff ≥ 15.6(4) K, while for the CoEr(III) analogue Ueff ≥ 9.9(8) K. The magnetic properties are discussed in terms of distortions of the 4f electron cloud. PMID:27180723

  1. 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.

  2. Synthesis and Photoluminescence Properties of Sr2Be2B2O7 Doped with Dy3+, Sm3+, Tb3+, and Pb2+

    NASA Astrophysics Data System (ADS)

    Pekgözlü, İ.; Karabulut, H.; Mergen, A.; Basak, A. S.

    2016-07-01

    Pure and Dy3+-, Sm3+-, Tb3+-, and Pb2+-doped Sr2Be2B2O7 materials were prepared by a solution combustion synthesis method. The phase analysis of all synthesized materials was carried out using powder XRD. The photoluminescent properties of Dy3+-, Sm3+-, Tb3+-, and Pb2+-doped Sr2Be2B2O7 materials were investigated using a spectrofl uorometer at room temperature. The fi rst luminescent material, Sr2Be2B2O7:Dy3+, emits 478-493, 573, and 661 nm upon excitation with 344 nm; Sr2Be2B2O7:Sm3+ emits 563-574, 599-613, 647-666, and 705-713 nm upon excitation with 395 nm; Sr2Be2B2O7:Tb3+ emits 489, 545, 584-591, and 622 nm upon excitation with 248 nm; Sr2Be2B2O7:Pb2+ emits 371 nm upon excitation with 281 nm. Also, the dependence of the emission intensity on the activator ion (Dy3+, Sm3+, Tb3+, and Pb2+) concentration for the Sr2Be2B2O7 was studied. It was observed that the concentration quenching of Dy3+, Sm3+, Tb3+, and Pb2+ in Sr2Be2B2O7 is 0.05, 0.02, 0.07, and 0.02 mol.%, respectively.

  3. Float zone growth of Dy:GdVO 4 single crystals for potential use in solid-state yellow lasers

    NASA Astrophysics Data System (ADS)

    Higuchi, Mikio; Sasaki, Ryo; Takahashi, Junichi

    2009-10-01

    Single crystals of dysprosium-doped gadolinium orthovanadate (Dy:GdVO 4) were successfully grown by the floating zone method and their fluorescence properties were investigated. The as-grown crystals did not contain any macroscopic defects such as cracks and inclusions for any Dy-concentration of up to 4 at%. Every crystal showed optical homogeneity under observation with a polarizing microscope; that is, no low-angle grain boundaries and growth striations were detected. In the visible region, two distinct fluorescence bands were observed around 480 and 575 nm, corresponding to 4F 9/2→ 6H 15/2 and 4F 9/2→ 6H 13/2 transitions, respectively. The excitation spectrum for the emission of 573 nm indicates the possibility to use a commercially available laser diode of 450 nm as a pumping source for solid-state yellow laser.

  4. 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 μB to zero, the magnetic moment m Gd remains unchanged and almost coincides with the magnetic moment of the free atom (7 μB), 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.

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

    NASA Astrophysics Data System (ADS)

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

    1999-06-01

    The magnetostrictive properties of TbDyFe/Nb multilayers containing 2 at% Zr as an additive have been investigated after different annealing treatments for the (Terfenol-D near) composition of [Tb 0.27Dy 0.73] 0.27Fe 0.73. The multilayer structure has been produced by ion-beam sputtering on a sapphire substrate. After 10 min annealing of the multilayers at temperatures from 873 to 973 K the parallel magnetostriction increased from λ‖(0.8 T)=265 to 520 ppm accompanied by an increase of the magnetic phase transition temperature from TC=333 to 592 K, while the increase of the coercive fields from μ0Hc<5 to 75 mT lies distinctively below 100 mT. These properties are suitable for applications of giant magnetostrictive films in microsystems where values of λ>500 ppm, TC>500 K and μ0Hc≪100 mT are required. Establishing a nanocrystalline microstructure with grain sizes d< dc˜15 nm ( dc is the critical grain diameter) smaller than the exchange length is essential for the combination of intrinsic magnetic properties (increased λ and TC) with soft magnetic properties ( μ0Hc of a few mT) as typical for an amorphous microstructure. It is shown by microstructural XRD and TEM investigations that such a nanocrystalline microstructure can be realized by a suitable heat treatment of TbDyFe+Zr/Nb multilayers. Introducing Nb spacer layers effectively reduces grain growth for certain annealing temperatures while Zr is assumed to play a dominant role in forming nucleation centers of nanograins. In combination, both effects can be well used to optimize the magnetostrictive layer properties.

  6. X-ray excited photoluminescence near the giant resonance in solid-solution Gd(1-x)Tb(x)OCl nanocrystals and their retention upon solvothermal topotactic transformation to Gd(1-x)Tb(x)F3.

    PubMed

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

    2016-01-14

    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

  7. 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 550°C. 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.

  8. 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

  9. 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.

  10. Laser Resonance Ionization Spectroscopy of the Lanthanides Tb, Dy and Ho as Homologues to Actinides and Super Heavy Elements

    SciTech Connect

    Gottwald, T.; Lassen, J.; Liu, Yuan; Mattolat, C.; Raeder, S.; Wendt, K.

    2009-03-01

    At Oak Ridge National Laboratory (ORNL) spectroscopic investigations of the rare earth elements Tb, Dy and Ho were carried out using laser resonance ionization mass spectroscopy (RIMS). Detailed spectroscopic studies are necessary to develop highly efficient and selective excitation and ionization schemes. Those schemes, carefully worked out under off-line conditions are mandatory for employment at laser ion sources at on-line facilities for studies of exotic radioactive nuclei e.g. 146Tb, as well as for laser-based ultra trace isotope analysis. Additionally, this work serves as preparatory step for related investigations on actinide elements and in preparation of the heaviest elements, where spectroscopic data so far are scarce or not existing at all.

  11. 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.

  12. 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.

  13. Structure and Magnetic Properties of TB0.27 DY0.73FE1.9+xTI0.05 Compounds

    NASA Astrophysics Data System (ADS)

    Li, Song-Tao; Liu, He-Yan; Ren, Zhi; Lu, Zun-Ming; Li, Yang-Xian

    Structure, Curie temperature, and magnetostriction have been systemically investigated for Tb0.27Dy0.73 Fe1.9+xTi0.05 compounds using X-ray diffraction, vibrating sample magnetometer, and standard strain gauge technique. The samples show pure MgCu2-type Laves phase when x≥0.2, and a small amount of second phases appear when x>0.2. The lattice parameters and the Curie temperatures change modestly with increasing Fe content. The magnetostriction of Tb0.27Dy0.73Fe1.9+xTi0.05 compounds shows strong dependence on Fe content.

  14. 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.

  15. Rare-earth transition-metal chalcogenides Ln3MGaS7 (Ln=Nd, Sm, Dy, Er; M=Co, Ni) and Ln3MGaSe7 (Ln=Nd, Sm, Gd, Dy, M=Co; Ln=Nd, Gd, Dy, M=Ni)

    NASA Astrophysics Data System (ADS)

    Yin, Wenlong; Shi, Youguo; Kang, Bin; Deng, Jianguo; Yao, Jiyong; Wu, Yicheng

    2014-05-01

    Fifteen new rare-earth transition-metal chalcogenides, Ln3MGaS7 (Ln=Nd, Sm, Dy, Er; M=Co, Ni) and Ln3MGaSe7 (Ln=Nd, Sm, Gd, Dy, M=Co; Ln=Nd, Gd, Dy, M=Ni), have been synthesized by solid state reactions. They are isostructural, adopt Ce3Al1.67S7-related structure type, and crystallize in the non-centrosymmetric hexagonal space group P63. They adopt a three-dimensional framework composed of LnQ7 monocapped trigonal prisms with the interesting [MQ3]4- chains and isolated GaQ4 tetrahedra lying in two sets of channels in the framework. The magnetic susceptibility measurements on Ln3CoGaQ7 (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 Sm3CoGaSe7 deviates from the Curie-Weiss law as a result of the crystal field splitting.

  16. Sol-gel syntheses, luminescence, and energy transfer properties of α-GdB5O9:Ce(3+)/Tb(3+) phosphors.

    PubMed

    Sun, Xiaorui; Gao, Wenliang; Yang, Tao; Cong, Rihong

    2015-02-01

    Sol-gel method was applied to prepare homogenous and highly crystalline phosphors with the formulas α-GdB5O9:xTb(3+) (0 ≤ x ≤ 1), α-Gd1-xCexB5O9 (0 ≤ x ≤ 0.40), α-GdB5O9:xCe(3+), 0.30Tb(3+) (0 ≤ x ≤ 0.15) and α-GdB5O9:0.20Ce(3+), xTb(3+) (0 ≤ x ≤ 0.10). The success of the syntheses was proved by the linear shrinkage or expansion of the cell volumes against the substitution contents. In α-GdB5O9:xTb(3+), an efficient energy transfer from Gd(3+) to Tb(3+) was observed and there was no luminescence quenching. The exceptionally high efficiency of the f-f excitations of Tb(3+) implies that these phosphors may be good green-emitting UV-LED phosphors. For α-Gd1-xCexB5O9, Ce(3+) absorbs the majority of the energy and transfers it to Gd(3+). Therefore, the co-doping of Ce(3+) and Tb(3+) leads to a significant enhancement in the green emission of Tb(3+). Our current results together with the study on α-GdB5O9:xEu(3+) in the literature indicate that α-GdB5O9 is a good phosphor host with advantages including controllable preparation, diverse cationic doping, the absence of concentration quenching, and effective energy transfer. PMID:25532125

  17. Synthesis of disordered pyrochlores, ATi 2O 7 ( A=Y, Gd and Dy), by mechanical milling of constituent oxides

    NASA Astrophysics Data System (ADS)

    Fuentes, Antonio F.; Boulahya, Khalid; Maczka, Miroslaw; Hanuza, Jerzy; Amador, Ulises

    2005-04-01

    This paper reports the mechanochemical synthesis and the structural and microstructural characterization of three titanates, ATi 2O 7 ( A=Y, Gd and Dy), with a pyrochlore-like structure. Starting from stoichiometric mixtures of elemental oxides TiO 2 and AO 3, single-phase samples of highly disordered pyrochlores were obtained after milling. Differential thermal analysis of the as prepared powders showed in every case the presence of a single exothermic event at temperatures close to 800 °C. The evolution of the structure and microstructure of these highly-disordered pyrochlores with temperature was studied by combining XRD and IR and Raman spectroscopies. On heating, both the cation and anion arrays in Y 2Ti 2O 7 and Dy 2Ti 2O 7, order by two independent processes. The exothermic events observed in DTA have their origin in the ordering of the anion sublattice, whereas cation ordering progress smoothly with temperature. Gadolinium titanate, Gd 2Ti 2O 7, behaves differently to the other two compounds studied concerning the cation sublattice: no evidence of cation disorder is observed, even in the just-milled sample.

  18. 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).

  19. 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

  20. "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 < λ < 370 nm. A commercial UV light-emitting diode (LED) with λLED = 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.

  1. 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

  2. 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

    2016-02-28

    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 (1), [Ni2Pr(L-)6](NO3)0.48(OH)0.52 (2), [Ni2Tb(L-)6](NO3)0.5(Cl)0.5 (3) and [Ni2Dy2(L-2(o-vanillin)2(CO3)2(NO3)2(MeOH)2] (4). Structural analysis for 1-3 reveals that the lanthanide ion is sandwiched between two Ni(II) ions and the Ni⋯Ln⋯Ni metallic core displays a linear arrangement, with an average ∠Ni⋯Ln⋯Ni bond angle of 179.7°. Analysis of 4 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 1-4 reveal that the Ni(II) ions are coupled ferromagnetically with the Tb(III) (3) and Dy(III) (4) ions, and antiferromagnetically with the Pr(III) ion (2). For complex 1 a long range intramolecular ferromagnetic interaction is witnessed between the Ni(II) ions (Ni⋯Ni = 6.873(9) Å) via a closed shell La(III) ion. The magnetic data of 1 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 2-4 revealed that 3 and 4 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

  3. 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.

  4. 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.

  5. Magnetic susceptibility and parameters of electronic structure of Al2REM (Gd, Dy, and Ho) intermetallic compounds at high temperatures

    NASA Astrophysics Data System (ADS)

    Uporova, N. S.; Uporov, S. A.; Sidorov, V. E.

    2011-08-01

    The magnetic susceptibility of Al2REM (REM = Gd, Dy, and Ho) intermetallic compounds is experimentally investigated by the Faraday method in a wide temperature interval (290-2000 K) in different magnetic fields (0.3-1.3 T). In the crystalline state, the temperature dependences of the susceptibility follow the generalized Curie-Weiss law. In the liquid phase, the magnetic susceptibility of these intermetallic compounds above the melting point increases for all examined samples. The parameters of the electronic structure of the compounds are calculated based on the experimental data. It is established that the effective magnetic moment per rareearth metal atom is smaller than that characteristic of the free REM+ ion.

  6. Competing γ-rigid and γ-stable vibrations in neutron-rich Gd and Dy isotopes

    NASA Astrophysics Data System (ADS)

    Budaca, R.; Budaca, A. I.

    2015-10-01

    An exactly separable version of the Bohr Hamiltonian which combines the γ-stable and γ-rigid axial vibration-rotation is used to describe the collective properties of few neutron-rich transitional nuclei. The coupling between the two types of collective motion is managed through a rigidity parameter which also influences the geometry of the shape phase space. While the γ-angular part of the problem associated to axially symmetric shapes is treated within the small angles approximation and the stiff γ oscillation hypothesis, the β vibration is described by means of a Davidson potential. The resulting model have three free parameters not counting the scale and was successfully applied for the description of the collective spectra for few heavier isotopes of Gd and Dy. In both cases a critical nucleus was identified through a discontinuous behavior in respect to the rigidity parameter and relevant experimental observables.

  7. Crystal-field parameters of the rare-earth pyrochlores R2Ti2O7 (R =Tb , Dy, and Ho)

    NASA Astrophysics Data System (ADS)

    Ruminy, M.; Pomjakushina, E.; Iida, K.; Kamazawa, K.; Adroja, D. T.; Stuhr, U.; Fennell, T.

    2016-07-01

    In this work, we present inelastic neutron scattering experiments which probe the single ion ground states of the rare-earth pyrochlores R2Ti2O7 (R =Tb , Dy, Ho). Dy2Ti2O7 and Ho2Ti2O7 are dipolar spin ices, now often described as hosts of emergent magnetic monopole excitations; the low-temperature state of Tb2Ti2O7 has features of both spin liquids and spin glasses, and strong magnetoelastic coupling. We measured the crystal-field excitations of all three compounds and obtained a unified set of crystal-field parameters. Additional measurements of a single crystal of Tb2Ti2O7 clarified the assignment of the crystal-field levels in this material and also revealed an example of a bound state between a crystal-field level and an optical phonon mode.

  8. 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

  9. 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.

  10. Formation of bcc non-equilibrium La, Gd and Dy alloys and the magnetic structure of Mg-stabilized. beta. Gd and. beta. Dy

    SciTech Connect

    Herchenroeder, J.W.

    1989-02-01

    The high temperature bcc allotrope of a rare earth metal has the potential for substantially different magnetic properties than the room temperature hexagonal (hcp or dhcp) counterpart because of its more symmetrical crystal field. The stabilization by alloying and quenching of this bcc phase was studied for La-M alloys where M is an non-rare earth metal from Group II or III. The factors influencing the stabilization, such as size of M and quench rate, are discussed. ..gamma..La (bcc) could be retained over a composition range around the eutectoid composition by Mg or Cd alloying. A comparison of T/sub o/ curves of the various alloy systems suggest that the eutectoid temperature of the La-M system must be approximately equal to or less than a critical T/sub o/ temperature of 515/degree/C if the bcc phase is to be retained by quenching. The thermal stability of ..beta..Gd (bcc) was investigated by DTA and isothermal annealing. It was found to transform to an intermediate phase before reverting to the equilibrium phases in contrast to ..gamma..La alloys which decompose directly on heating to the equilibrium phases. 71 refs., 52 figs., 7 tabs.

  11. Magnetic remanence in Yb14-xRExMnSb11 (RE=Tb, Dy, Ho) single crystals

    NASA Astrophysics Data System (ADS)

    Grebenkemper, Jason H.; Hu, Yufei; Abdusalyamova, M. N.; Makhmudov, F. A.; Kauzlarich, Susan M.

    2016-06-01

    Single crystals of Yb14-xRExMnSb11 (x~0.1, 0.4; RE = Tb, Dy, Ho) have been prepared as a solid solution by Sn flux reactions of the elements. They crystallize in the Ca14AlSb11 structure type in the I41/acd space group. The RE3+preferentially substitutes on the Yb(1) site which is the smallest volume Yb containing polyhedron. In the case of Ho3+, a small amount of Ho3+ also substitutes on the Yb(4) site. The ferromagnetic ordering temperature of Yb14MnSb11 is reduced from 53 K to 41 K as x increases and dependent on the identity of the RE. This is attributed to the reduction in carriers and reduced screening of the Mn2+ local moment. The effective moments, μeff, agree well with the calculated moments assuming the RE substitutes as a trivalent cation. The largest coercive field is observed for RE = Dy (1000 Oe). For the maximum x of Yb14-xRExMnSb11 there are enough carriers for the Ruderman-Kittel-Kasuya-Yosida (RKKY) mechanism of magnetic coupling via conduction electrons to still be valid in describing the ferromagnetic ordering.

  12. Effect of rare-earth (Er and Gd) substitution on the magnetic and multiferroic properties of DyFe0.5Cr0.5O3.

    PubMed

    Sharma, Mohit K; Basu, Tathamay; Mukherjee, K; Sampathkumaran, E V

    2016-10-26

    We report the results of our investigations on the influence of partial substitution of Er and Gd for Dy on the magnetic and magnetoelectric properties of DyFe0.5Cr0.5O3, which is known to be a multiferroic system. Magnetic susceptibility and heat capacity data, apart from confirming the occurrence of magnetic transitions at ~121 and 13 K in DyFe0.5Cr0.5O3, bring out that the lower transition temperature only is suppressed by rare-earth substitution. Multiferroic behavior is found to persist in Dy0.4Ln0.6Fe0.5Cr0.5O3 (Ln  =  Er and Gd). There is an evidence for magnetoelectric coupling in all these materials with qualitative differences in its behavior as the temperature is changed across these two transitions. Remnant electric polarization is observed for all the compounds. The most notable observation is that electric polarization is seen to get enhanced as a result of rare-earth substitution with respect to that in DyFe0.5Cr0.5O3. Interestingly, a similar trend is seen in the magnetocaloric effect, consistent with the existence of magnetoelectric coupling. The results thus provide evidence for the tuning of magnetoelectric coupling by rare-earth substitution in this family of oxides. PMID:27588356

  13. Prominent role of oxygen in the multiferroicity of DyMnO3 and TbMnO3: A resonant soft x-ray scattering spectroscopy study

    NASA Astrophysics Data System (ADS)

    Huang, S. W.; Lee, J. M.; Jeng, Horng-Tay; Shao, YuCheng; Wray, L. Andrew; Chen, J. M.; Qiao, R.; Yang, W. L.; Cao, Y.; Lin, J.-Y.; Schoenlein, R. W.; Chuang, Y.-D.

    2016-07-01

    Oxygen is known to play an important role in the multiferroicity of rare earth manganites; however, how this role changes with rare earth elements is still not fully understood. To address this question, we have used resonant soft x-ray scattering spectroscopy to study the F -type (0 ,τ ,0 ) diffraction peak from the antiferromagnetic order in DyMnO3 and TbMnO3. We focus on the measurements at O K edge of these two manganites, supplemented by the results at Mn L2 and Dy M5 edge of DyMnO3. We show that the electronic states of different elements are coupled more strongly in DyMnO3 than in TbMnO3, presumably due to the stronger lattice distortion and the tendency to develop E-type antiferromagnetism in the ferroelectric state that promote the orbital hybridization. We also show that the anomaly in the correlation length of (0 ,τ ,0 ) peak in DyMnO3 signifies the exchange interaction between Mn and rare earth spins. Our findings reveal the prominent role of oxygen orbitals in the multiferroicity of rare earth manganites and the distinct energetics between them.

  14. 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.

  15. Search for excited superdeformed bands in {sup 151}Dy

    SciTech Connect

    Nisius, D.; Janssens, R.V.F.; Crowell, B.

    1995-08-01

    Following the first report of superdeformed (SD) bands with identical transition energies in the pairs ({sup 151}Tb*,{sup 152}Dy), ({sup 150}Gd*, {sup 151}Tb) and ({sup 153}Dy*, {sup 152}Dy) (where * denotes an excited SD band), it was proposed by Nazarewicz et al. that the observations could be understood in a strong-coupling approach if pseudo SU(3) symmetry were invoked. In this model there are three limiting values of the decoupling parameter; i.e. a = 0, {plus_minus}1. In the first two cases mentioned above the pairs of bands have nearly identical transition energies and are interpreted as proton excitations involving the [200]1/2 pseudospin orbital coupled to the {sup 152}Dy core, for which the value of the decoupling parameter is calculated to be a =+1.

  16. A novel emitting color tunable phosphor Ba3Gd(PO4)3: Ce3+, Tb3+ based on energy transfer

    NASA Astrophysics Data System (ADS)

    Jin, Yahong; Hu, Yihua; Chen, Li; Wang, Xiaojuan; Mu, Zhongfei; Ju, Guifang; Yang, Zhongfu

    2014-03-01

    A novel emitting color tunable phosphor Ba3Gd(PO4)3: Ce3+, Tb3+ was synthesized by the traditional high temperature solid state reaction method. The photoluminescence (PL) and energy transfer (ET) properties of Ce3+ and Tb3+ doped Ba3Gd(PO4)3 host were studied in detail. The obtained phosphors show both a blue emission from Ce3+ and a yellowish-green emission from Tb3+ with considerable intensity under ultraviolet (UV) excitation (~310 nm). When the content of Ce3+ was fixed at 0.05, the emission chromaticity coordinates could be adjusted from blue to green region by tuning the contents of Tb3+ ions from 0.01 to 0.5 through an ET process. The critical distance between Ce3+ and Tb3+ is 16.16 Å. The ET mechanism from Ce3+ to Tb3+ ions was proved to be dipole-dipole interaction. The developed phosphor exhibits a strong excitation in UV spectral region and high efficient ET from Ce3+ to Tb3+ ions. It may find applications as a green light-emitting UV-convertible phosphor in white LED devices. Furthermore, a white light emission phosphor Ba3Gd(PO4)3: Ce3+, Tb3+, Mn2+ was also investigated.

  17. 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

  18. 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.

  19. 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}

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. 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.

  5. Optical properties and chemical composition analyses of mixed rare earth oxyorthosilicate (R2SiO5, R=La, Gd and Y) doped Dy3+ phosphors prepared by urea-assisted solution combustion method

    NASA Astrophysics Data System (ADS)

    Ogugua, S. N.; Shaat, S. K. K.; Swart, H. C.; Ntwaeaborwa, O. M.

    2015-08-01

    Dysprosium (Dy3+) doped lanthanum gadolinium oxyorthosilicate (LaGdSiO5), lanthanum yttrium oxyorthosilicate (LaYSiO5) and gadolinium yttrium oxyorthosilicate (GdYSiO5) phosphors (in powder form) were synthesized by urea-assisted combustion method. The X-ray diffractometer analysis confirmed that the LaGdSiO5, LaYSiO5 and GdYSiO5 crystalized in monoclinic phases. The chemical composition of the phosphors was analyzed by measuring the atomic and molecular ionic species using the time of flight secondary ion mass spectroscopy (ToF SIMS). In addition, ToF SIMS imaging technique was used to determine the distribution of the Dy3+ dopant ions on the surface on the phosphors. The average crystallite sizes and lattice strains of the phosphor were increased by Dy3+ doping. The field emission scanning electron microscope images showed that the powders were made up of an agglomeration of particles with no regular shape. The photoluminescence data showed narrow line emission peaks at the wavelengths of 485 nm (minor emission) and 573 nm (major emission) associated with the f→f transitions of Dy3+. The photoluminescence (PL) measurements showed that the emission peak of LaGdSiO5:Dy3+ was ~3× more intense than those of LaYSiO5:Dy3+ and GdYSiO5:Dy3+ when excited using monochromatic xenon lamp with a wavelength of 241 nm. However, when the powders were excited using a 325 nm He-Cd laser, the highest PL emission intensity was observed from GdYSiO5:Dy3+.

  6. 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.

  7. 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.

  8. Mueller matrix ellipsometry studies of the optical phonons and crystal field excitations in multiferroic orthoferrites RFeO3 (R=Tb,Dy)

    NASA Astrophysics Data System (ADS)

    Martinez, V. A.; Stanislavchuk, T. N.; Sirenko, A. A.; Litvinchuk, A. P.; Wang, Yazhong; Cheong, S. W.

    Optical properties of multiferroic orthoferrites RFeO3 (R=Tb,Dy) bulk crystals have been studied in the far-infrared range from 50 to 1000 cm-1 and temperatures from 7 K to 300 K. Mueller matrix and rotating analyzer ellipsometry measurements were carried out at the U4IR beamline of the National Synchrotron Light Source at Brookhaven National Lab. Optical phonon spectra and crystal field excitations were measured for all three orthorhombic axes of RFeO3. In the experimental temperature dependencies of the phonon frequencies we found non-Grüneisen behavior caused by the electron-phonon and spin-phonon interactions. We determined the symmetries and selection rules for the crystal field transitions in Tb3+ and Dy3+ ions. Magnetic field dependencies of the optical spectra allowed us to determine anisotropy of the crystal field g-factors for Tb3+ and Dy3+ ions. This Project is supported by collaborative DOE Grant DE-FG02-07ER46382 between Rutgers U. and NJIT. Use of NSLS-BNL was supported by DOE DE-AC02-98CH10886. V.A. Martinez was supported by NEU NSF-1343716.

  9. Luminescence properties of Ca4Y6(SiO4)6O:RE3+ (RE = Eu, Tb, Dy, Sm and Tm) under vacuum ultraviolet excitation

    NASA Astrophysics Data System (ADS)

    Wen, Yan; Wang, Yuhua; Liu, Bitao; Zhang, Feng

    2012-03-01

    The vacuum ultraviolet excited luminescent properties of Eu3+, Tb3+, Dy3+, Sm3+ and Tm3+ in the matrices of Ca4Y6(SiO4)6O were investigated. The bands at about 173 nm in the vacuum ultraviolet excited spectra were attributed to host lattice absorption of the matrix Ca4Y6(SiO4)6O. For Eu3+-doped samples, the O2- → Eu3+ CTB was identified at 258 nm. Typical 4f-5d absorption bands in the region of 195-300 nm were observed in Tb3+-doped samples. For Dy3+-doped and Sm3+-doped samples, the broad excitation bands consisted of host absorptions, CTB and f-d transition. For Tm3+-doped samples, the O2- → Tm3+ CTB was located at 191 nm. About the color purity and emission intensity, Ca4Y6(SiO4)6O:Tb3+ is an attractive candidate of green light PDP phosphor, and Ca4Y6(SiO4)6O:Dy3+ has potential application in the field of mercury-free lamps.

  10. Narrow spectral emission CaMoO4: Eu3+, Dy3+, Tb3+ phosphor crystals for white light emitting diodes

    NASA Astrophysics Data System (ADS)

    Khanna, A.; Dutta, P. S.

    2013-02-01

    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 Ln3+(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 °C. Using the excitation wavelengths of 465 nm, 454 nm and 489 nm for CaMoO4: Eu3+, CaMoO4: Dy3+ and CaMoO4: Tb3+, 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 Eu3+, Dy3+ and Tb3+, respectively, provided the highest luminescence intensity.

  11. 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.

  12. 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.; 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

  13. 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.

  14. First-principles calculation and experimental investigation of lattice dynamics in the rare-earth pyrochlores R2Ti2O7 (R =Tb,Dy,Ho)

    NASA Astrophysics Data System (ADS)

    Ruminy, M.; Valdez, M. Núñez; Wehinger, B.; Bosak, A.; Adroja, D. T.; Stuhr, U.; Iida, K.; Kamazawa, K.; Pomjakushina, E.; Prabakharan, D.; Haas, M. K.; Bovo, L.; Sheptyakov, D.; Cervellino, A.; Cava, R. J.; Kenzelmann, M.; Spaldin, N. A.; Fennell, T.

    2016-06-01

    We present a model of the lattice dynamics of the rare-earth titanate pyrochlores R2Ti2O7 (R =Tb ,Dy,Ho) , which are important materials in the study of frustrated magnetism. The phonon modes are obtained by density functional calculations, and these predictions are verified by comparison with scattering experiments. Single crystal inelastic neutron scattering is used to measure acoustic phonons along high symmetry directions for R =Tb , Ho; single crystal inelastic x-ray scattering is used to measure numerous optical modes throughout the Brillouin zone for R =Ho ; and powder inelastic neutron scattering is used to estimate the phonon density of states for R =Tb , Dy, Ho. Good agreement between the calculations and all measurements is obtained, allowing confident assignment of the energies and symmetries of the phonons in these materials under ambient conditions. Knowledge of the phonon spectrum is important for understanding spin-lattice interactions, and can be expected to be transferred readily to other members of the series to guide the search for unconventional magnetic excitations.

  15. 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

  16. 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.

  17. 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.

  18. Syntheses, crystal structures and vibrational spectra of K Ln(SO 4) 2·H 2O ( Ln=La, Nd, Sm, Eu, Gd, Dy)

    NASA Astrophysics Data System (ADS)

    Kazmierczak, Karolina; Höppe, Henning A.

    2010-09-01

    The potassium lanthanide double sulphates K Ln(SO 4) 2·H 2O ( 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 K Ln(SO 4) 2·H 2O ( Ln=Nd, Sm, Eu, Gd, Dy) crystallise monoclinically ( Ln=Sm: P2 1/ c, Z=4, a=10.047(1), b=8.4555(1), c=10.349(1) Å, w R2=0.060, R1=0.024, 945 reflections, 125 parameters) while KLa(SO 4) 2·H 2O adopts space group P3 221 (Z=3, a=7.1490(5), c=13.2439(12) Å, w R2=0.038, R1=0.017, 695 reflections, 65 parameters). The coordination environment of the lanthanide ions in K Ln(SO 4) 2·H 2O 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 K Ln(SO 4) 2·H 2O and the UV-vis reflection spectra of KEu(SO 4) 2·H 2O and KNd(SO 4) 2·H 2O are also reported.

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

    SciTech Connect

    Kazmierczak, Karolina; 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.

  20. Crystal architecture of R(2)SnS(5) (R = Pr, Nd, Gd and Tb): crystal structure relationships in chalcogenides.

    PubMed

    Daszkiewicz, Marek; Gulay, Lubomir D; Shemet, Vasylyna Ya

    2008-04-01

    The crystal structure of the R(2)SnS(5) (R = Pr, Nd, Gd and Tb) compounds has been investigated using X-ray single-crystal diffraction. Crystal architecture and structural relationships among U(3)S(5), Y(2)HfS(5), R(2)SnS(5) compounds are discussed and a structural origin is determined. It is shown that the complex architecture of the crystal structure of Eu(5)Sn(3)S(12) is a result of interweaving of the simple crystal structures. The location of the copper ions in the non-stoichiometric compound Y(2)Cu(0.20)Sn(0.95)S(5) is proposed on the basis of comparative analysis of the R-S interatomic distances in the R(2)SnS(5) series of compounds. PMID:18369288

  1. 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.

  2. {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

  3. 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.

  4. 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

  5. Preparation and photophysical studies of [Ln(hfac)3DPEPO], Ln = Eu, Tb, Yb, Nd, Gd; interpretation of total photoluminescence quantum yields.

    PubMed

    Congiu, Martina; Alamiry, Mohamed; Moudam, Omar; Ciorba, Serena; Richardson, Patricia R; Maron, Laurent; Jones, Anita C; Richards, Bryce S; Robertson, Neil

    2013-10-01

    Synthesis and photophysical characterisation of [Ln(hfac)3DPEPO] complexes (with Ln = Eu, Tb, Yb, Nd, Gd) has been carried out to investigate the factors responsible for the variation in total photoluminescence quantum yield within this family of emissive lanthanide complexes. Electronic absorption and emission spectroscopy, in conjunction with DFT calculations of the excited state of the Eu complex, elucidate the role of each ligand in the sensitisation of the lanthanide through the antenna effect. The X-ray crystal structure of [Gd(hfac)3DPEPO] has been determined and shows an 8-coordinate environment around the Gd and a ten-membered chelate ring involving the DPEPO ligand. Total photoluminescence quantum yields were measured to be 6%, 1% and 2% for Ln = Tb, Nd and Yb, respectively, in comparison with around 80% for Ln = Eu. The lower quantum yield for Nd and Yb, compared with Eu, can be attributed to more efficient quenching of the excited Ln state by high-energy oscillations within the ligands, whereas the lower quantum yield for Tb is assigned to a combination of poor energy transfer from the ligand excited state to the Tb and longer radiative lifetime. PMID:23900430

  6. 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.

  7. 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

  8. 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

  9. Honeycombs of triangles and magnetic frustration in SrL{sub 2}O{sub 4} (L=Gd, Dy, Ho, Er, Tm, and Yb)

    SciTech Connect

    Karunadasa, H.; Regan, K.A.; Cava, R.J.; Huang, Q.; Lynn, J.W.; Ueland, B.G.; Schiffer, P.

    2005-04-01

    The crystal structures, magnetic order, and susceptibility have been investigated for magnetically frustrated SrDy{sub 2}O{sub 4}, SrHo{sub 2}O{sub 4}, SrEr{sub 2}O{sub 4}, SrTm{sub 2}O{sub 4}, and SrYb{sub 2}O{sub 4}. Powder neutron-diffraction structural refinements reveal columns of LO{sub 6} octahedra that run along one crystallographic direction, with Sr-O polyhedra in the interstices. The lanthanide sublattice displays multiple triangular interconnections: one-dimensional strings form the backbones of four types of chains of lanthanide triangles sharing edges arranged in a honeycomb pattern. This crystal structure produces strong geometric frustration for the magnetic system that is evidenced in both magnetic susceptibility and neutron-scattering data at low temperatures. The susceptibility measurements for the series, including SrGd{sub 2}O{sub 4} for which data are also reported, lack the sharp features characteristic of three-dimensional long-range magnetic ordering. Metamagnetic behavior is observed in the magnetization vs applied field data at 1.8 K for the cases of L=Dy, Er, and Ho. Magnetic neutron-scattering studies for the Dy and Er materials show only very broad magnetic scattering at low temperatures, while the Ho system exhibits long-range two-dimensional order. Any magnetic scattering in the Tm and Yb compounds, if present, was too weak to be detected in these measurements.

  10. 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

  11. 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

  12. 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.

  13. 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.

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

    NASA Astrophysics Data System (ADS)

    Diguet, Gildas; Lin, Guoxing; Chen, Jincan

    2012-10-01

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

  15. 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.

  16. The prominent role of oxygen in the multiferroicity of DyMnO3 and TbMnO3: a resonant soft x-ray scattering spectroscopy study

    DOE PAGESBeta

    S. W. Huang; Lee, J. M.; Jeng, H. -T.; Shao, Y.; Wray, L. A.; Chen, J. M.; Qiao, R.; Yang, W. L.; Cao, Y.; Lin, J. -Y.; et al

    2016-07-21

    Oxygen is known to play an important role in the multiferroicity of rare earth manganites; however, how this role changes with rare earth elements is still not fully understood. To address this question, we have used resonant soft x-ray scattering spectroscopy to study the F-type (0; ; 0) diffraction peak from the antiferromagnetic order in DyMnO3 and TbMnO3. We focus on the measurements at O K-edge of these two manganites, supplemented by the results at Mn L2- and Dy M5-edge of DyMnO3. We show that the electronic states of di erent elements are coupled more strongly in DyMnO3 than inmore » TbMnO3, presumably due to the stronger lattice distortion and the tendency to develop E-type antiferromagnetism in the ferroelectric state that promote the orbital hybridization. We also show that the anomaly in the correlation length of (0; ; 0) peak in DyMnO3 signifies the exchange interaction between Mn and rare earth spins, which is absent in TbMnO3. Our findings reveal the prominent role of oxygen orbitals in the multiferroicity of rare earth manganites and the distinct energetics between them.« less

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

    SciTech Connect

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

    2013-06-10

    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.

  18. Syntheses, structures, and magnetic analyses of a family of heterometallic hexanuclear [Ni4M2] (M = Gd, Dy, Y) compounds: observation of slow magnetic relaxation in the Dy(III) derivative.

    PubMed

    Ke, Hongshan; Zhao, Lang; Guo, Yang; Tang, Jinkui

    2012-02-20

    We described the syntheses, crystal structures, and magnetic behavior of a novel series of heterometallic [Ni(4)M(2)] [M = Gd (1), Dy (2) and Y (3)] hexanuclear compounds afforded by the reaction of rare-earth(III) nitrate, nickel(II) acetate, and Schiff-base ligand 2-(2-hydroxy-3-methoxybenzylideneamino)phenol (H(2)L) in a mixture of ethanol and dichloromethane in the presence of triethylamine. Single-crystal X-ray diffraction measurements reveal that all three compounds have a metal core made up of two Ni(2)MO(4) defective cubanes. The magnetic properties of all compounds have been studied. Solid-state direct-current magnetic susceptibility analyses demonstrate competing antiferromagnetic and ferromagnetic interactions within both compounds 1 and 3. Solid-state alternating-current magnetic susceptibility investigations show a frequency-dependent out-of-phase signal for compound 2 below 4 K, suggestive of slow magnetic relaxation. PMID:22320187

  19. Hydrothermal synthesis and luminescent properties of color-tunable Dy3+ doped and Eu3+/Tb3+ co-doped MMoO4 (M=Ca, Sr, Ba) phosphors

    NASA Astrophysics Data System (ADS)

    Li, Linlin; Li, Ruiqing; Zi, Wenwen; Gan, Shucai

    2015-02-01

    Dy3+ doped and Eu3+/Tb3+ co-doped MMoO4 (M=Ca, Sr, Ba) phosphors have been successfully prepared via a simple surfactant-free hydrothermal method. Their crystal structure, morphology, and luminescent characteristics were investigated. The results show that the as-prepared CaMoO4 particles have the cylinder-like shape, SrMoO4 samples present dumbbell-like shape, and the as-prepared BaMoO4 products show micro-rods shape with a length of 5-15 μm. MMoO4:Dy3+ phosphors exhibited the characteristic excitation and emission transitions of Dy3+ and most of the chromaticity coordinates are located in the white-light region. In addition, with increasing Dy3+ ions concentration the color changes gradually from near blue to near yellow. All the characteristic emissions of Eu3+ and Tb3+ can be observed in Eu3+/Tb3+ co-doped MMoO4 phosphors, and the emission color can be easily tuned from red, through yellow or green-yellow, to green by simply adjusting the relative doping concentrations of the Eu3+ and Tb3+ ions. The present work suggests that these phosphors may have potential application for light-emitting diodes (LEDs).

  20. 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.

  1. 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.

  2. 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}.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Ionic conductivity of dense BaZr0.5Ce0.3Ln0.2O3-δ (Ln = Y, Sm, Gd, Dy) electrolytes

    NASA Astrophysics Data System (ADS)

    Bu, Junfu; Jönsson, Pär G.; Zhao, Zhe

    2014-12-01

    BaZr0.5Ce0.3Ln0.2O3-δ (BZCLn532, Ln = Y, Sm, Gd, Dy) based electrolytes were successfully synthesized by a cost-effective solid-state reactive sintering (SSRS) method while using 1.0 wt.% NiO as a sintering aid. Dense pellets of BZCLn532 compounds can be prepared at sintering temperatures of 1600 °C (BZCY532) and 1400 °C (BZCS532, BZCG532 and BZCD532). The conductivities of the dense BZCLn532 ceramics were tested in dry and wet air at temperatures of 700 °C-200 °C. On the basis of the obtained results, it could be concluded that the BZCY532-based electrolyte show promise for use as oxygen-ion conductors and proton conductors in intermediate temperature solid oxide fuel cells (ITSOFCs).

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

    PubMed

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

    2014-11-17

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

  10. 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

  11. 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.

  12. Crystal Structures and Reference Powder Patterns of BaR2ZnO5 (R = La, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, and Tm)

    PubMed Central

    Kaduk, J. A.; Wong-Ng, W.; Greenwood, W.; Dillingham, J.; Toby, B. H.

    1999-01-01

    Reference x-ray powder patterns and the crystal structures of the lanthanide compounds, BaR2ZnO5, in which R = La, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, or Tm, were determined by the x-ray Rietveld refinement technique. A structural trend was confirmed for this series of compounds. The compounds with smaller ionic radii (R = Sm, Eu, Gd, Dy, Ho, Y, Er, or Tm) are isostructural to the orthorhombic “green phase” (BaY2CuO5). The lattice parameters for compounds with R = Tm to Sm range from a = 7.01855(9) Å to 7.20452(14) Å, b = 12.25445 (17) Å to 12.5882(2) Å, and c = 5.6786(14) Å to 5.81218(11) Å, respectively. R is sevenfold coordinated inside a monocapped trigonal prism. These prisms share edges to form wave-like chains parallel to the long b-axis. The BaR2ZnO5 compounds which contain larger size R (La and Nd) crystallize in the tetragonal space group I4/mcm. The lattice parameters are a = 6.90982(10) and c = 11.5977(2) Å for BaLa2ZnO5, and a = 6.75979(5) Å and c = 11.54560(12) Å for BaNd2ZnO5. The structure consists of ZnO4 tetrahedra (instead of planar CuO4 groups as found in BaR2CuO5) with 10-fold coordinated bicapped square prismatic Ba and 8-fold coordinated bicapped trigonal prismatic R ions between them. The reference x-ray powder patterns will be submitted to the Powder Diffraction File (PDF).

  13. Effects of sublattice positions and of asphericity of 4 f and 5 d charge densities on X-ray diffraction intensities in Tb and Dy

    NASA Astrophysics Data System (ADS)

    Eagles, D. M.

    1984-10-01

    Aspherical 5 d charge densities in a model for 5 d electrons in the heavy rare-earth metals developed by the present author produce small differences in X-ray diffraction intensities from those predicted by more traditional theories, in which anisotropy is significant only for 4 f shells. Diffraction intensities in Tb and Dy depend both on asphericities of charge densities and on the value of a parameter measuring the relative positions of sublattices in the low-temperature orthorhombically distorted structure of these metals. Predictions of ratios of intensities are made for several pairs of lines in each metal. Relative intensity measurements to an accuracy of the order of 1% should be sufficient to determine the sublattice displacements, but to distinguish between the model with large 5 d electric quadrupole and octupole moments and traditional theories would require accuracies of the order of 0.3%.

  14. Magnetostructural phase transitions and magnetocaloric effect in Tb-Dy-Ho-Co-Al alloys with a Laves phase structure

    NASA Astrophysics Data System (ADS)

    Tereshina, I. S.; Chzhan, V. B.; Tereshina, E. A.; Khmelevskyi, S.; Burkhanov, G. S.; Ilyushin, A. S.; Paukov, M. A.; Havela, L.; Karpenkov, A. Yu.; Cwik, J.; Koshkid'ko, Yu. S.; Miller, M.; Nenkov, K.; Schultz, L.

    2016-07-01

    The influence of simultaneous substitution within the rare earth (R) and Co sublattices on the structural, magnetic, and magnetocaloric properties of the Laves phase RCo2-type compounds is studied. Main attention is devoted to the studies of the magnetostructural phase transitions and the transition types with respect to the alloy composition. Multicomponent alloys Tbx(Dy0.5Ho0.5)1-xCo2 and Tbx(Dy0.5Ho0.5)1-xCo1.75Al0.25 were prepared with the use of high purity metals. Majority of the Tbx(Dy0.5Ho0.5)1-xCo2 alloys exhibit magnetic transitions of the first-order type and a large magnetocaloric effect. The substitution of Al for Co in Tbx(Dy0.5Ho0.5)1-xCo2 increases the Curie temperature (TC) but changes the transition type from first-to the second-order. The discussion of the physical mechanisms behind the observed phenomena is given on the basis of the first principles electronic-structure calculations taking into account both the atomic disorder and the magnetic disorder effects at finite temperatures. The advantage of Al-containing materials is that sufficiently high magnetocaloric effect values are preserved at T > TC.

  15. 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

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

    SciTech Connect

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

    2007-11-01

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

  17. 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

  18. 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.

  19. Host-sensitized luminescence of Dy{sup 3+}, Pr{sup 3+}, Tb{sup 3+} in polycrystalline CaIn{sub 2}O{sub 4} for field emission displays

    SciTech Connect

    Liu Xiaoming; Pang Ran; Li Qin; Lin Jun

    2007-04-15

    CaIn{sub 2}O{sub 4}:Dy{sup 3+}/Pr{sup 3+}/Tb{sup 3+} blue-white/green/green phosphors were prepared by the Pechini sol-gel process. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), diffuse reflectance, photoluminescence (PL) and cathodoluminescence (CL) spectra as well as lifetimes were utilized to characterize the samples. The XRD results reveal that the samples begin to crystallize at 800 deg. C and pure CaIn{sub 2}O{sub 4} phase can be obtained after annealing at 900 deg. C. The FE-SEM images indicate that the CaIn{sub 2}O{sub 4}:Dy{sup 3+}, CaIn{sub 2}O{sub 4}:Pr{sup 3+} and CaIn{sub 2}O{sub 4}:Tb{sup 3+} samples consist of spherical grains with size around 200-400 nm. Under the excitation of ultraviolet light and low-voltage electron beams (1-5 kV), the CaIn{sub 2}O{sub 4}:Dy{sup 3+}, CaIn{sub 2}O{sub 4}:Pr{sup 3+} and CaIn{sub 2}O{sub 4}:Tb{sup 3+} phosphors show the characteristic emissions of Dy{sup 3+} ({sup 4}F{sub 9/2}-{sup 6}H{sub 15/2} and {sup 4}F{sub 9/2}-{sup 6}H{sub 13/2} transitions, blue-white), Pr{sup 3+} ({sup 3}P{sub 0}-{sup 3}H{sub 4}, {sup 1}D{sub 2}-{sup 3}H{sub 4} and {sup 3}P{sub 1}-{sup 3}H{sub 5} transitions, green) and Tb{sup 3+} ({sup 5}D{sub 4}-{sup 7}F{sub 6,5,4,3} transitions, green), respectively. All the luminescence is resulted from an efficient energy transfer from the CaIn{sub 2}O{sub 4} host lattice to the doped Dy{sup 3+}, Pr{sup 3+} and Tb{sup 3+} ions, and the corresponding luminescence mechanisms have been proposed. - Graphical abstract: The CaIn{sub 2}O{sub 4}:Dy{sup 3+}/Pr{sup 3+}/Tb{sup 3+} blue-white/green/green phosphors were prepared by the Pechini sol-gel process. Under the excitation of ultraviolet light and low-voltage electron beams (1-5 kV), the CaIn{sub 2}O{sub 4}:Dy{sup 3+}, CaIn{sub 2}O{sub 4}:Pr{sup 3+} and CaIn{sub 2}O{sub 4}:Tb{sup 3+} phosphors show the characteristic emissions of Dy{sup 3+} ({sup 4}F{sub 9/2}-{sup 6}H{sub 15/2} and {sup 4}F{sub 9/2}-{sup 6}H{sub 13

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

    PubMed

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

    2012-02-20

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

  1. 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.

  2. Ag island film-enhanced rare earth co-luminescence effect of Tb-Gd-protein-sodium dodecyl benzene sulfonate system and sensitive detection of protein.

    PubMed

    Sun, Chang Xia; Wu, Xia; Zhou, Hai Ping; Wang, Fei; Ding, Hong Hong; Zhao, Liang Liang; Yang, Jing He

    2008-09-15

    This paper reported the coupling technique of Ag island film-enhanced fluorescence with rare earth co-luminescence effect of Tb-Gd-sodium dodecyl benzene sulfonate (SDBS)-protein system. While the collagen is used as the separator between Ag island film and the fluorophore because it not only can decrease the fluorescence of the blank, but also can promote the adsorption of other proteins and change the conformation of the protein. The effects of Ag island film on both the fluorescence and resonance energy transfer process of Tb-Gd-SDBS-protein system are studied, finding that Ag island film can enhance the energy transfer efficiency of this system, resulting in fluorescence enhancement about tenfold compared with this system without Ag island film. Therefore, this technique is used for the detection of proteins as low as 0.72 ng/mL for BSA and 1.3 ng/mL for HSA. In addition, Ag island film can also change the energy transfer process of Tb-SDBS-protein system. PMID:18761153

  3. 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

  4. Magnetic ordering in Sc2CoSi2-type R2FeSi2 (R=Gd, Tb) and R2CoSi2 (R=Y, Gd-Er) compounds

    NASA Astrophysics Data System (ADS)

    Morozkin, A. V.; Knotko, A. V.; Yapaskurt, V. O.; Pani, M.; Nirmala, R.; Quezado, S.; Malik, S. K.

    2016-09-01

    Magnetic and magnetocaloric properties of Sc2CoSi2-type R2TSi2 (R=Gd-Er, T=Fe, Co) compounds have been studied using magnetization data. These indicate the presence of mixed ferromagnetic and antiferromagnetic interactions in these compounds. One observes a ferromagnetic transition followed by an antiferromagnetic order and a further possible spin-reorientation transition at low temperatures. Compared to Gd2{Fe, Co}Si2, the Tb2FeSi2 and {Tb-Er}2CoSi2 compounds exhibit remarkable hysteresis (for e.g. Tb2FeSi2 shows residual magnetization Mres/Tb=2.45 μB, coercive field Hcoer=14.9 kOe, and critical field Hcrit 5 kOe at 5 K) possibly due to the magnetocrystalline anisotropy of the rare earth. The R2{Fe, Co}Si2 show relatively small magnetocaloric effect (i.e. isothermal magnetic entropy change, ΔSm) around the magnetic transition temperature: the maximal value of MCE is demonstrated by Ho2CoSi2 (ΔSm=-8.1 J/kg K at 72 K and ΔSm=-9.4 J/kg K at 23 K in field change of 50 kOe) and Er2CoSi2 (ΔSm=-13.6 J/kg K at 32 K and ΔSm=-8.4 J/kg K at 12 K in field change of 50 kOe).

  5. Color-tunable properties and energy transfer in Ba3GdNa(PO4)3F:Eu2+, Tb3+ phosphor pumped for n-UV w-LEDs

    NASA Astrophysics Data System (ADS)

    Zeng, Chao; Liu, Haikun; Hu, Yingmo; Liao, Libing; Mei, Lefu

    2015-11-01

    A series of Eu2+ and Eu2+/Tb3+ co-doped Ba3GdNa(PO4)3F phosphors have been synthesized via a high temperature solid-state reaction. The relative intensity of PL spectra of Ba3GdNa(PO4)3F:xEu2+ increases with increasing x value, and reaches a maximum at x=0.04. Ba3GdNa(PO4)3F:Eu2+, Tb3+ phosphors exhibit a broad excitation band ranging from 220 to 450 nm, which matches perfectly with the characteristic emission of n-UV light-emitting diode (LED) chips. Upon 365 nm excitation, the Ba3GdNa(PO4)3F:Eu2+, Tb3+ phosphors show two dominating bands peaked at 466 and 543 nm, which are assigned to the 4f7→4f65d1 transition of the Eu2+ ions and the 5D4→7F5 transition of the Tb3+ ions, respectively. In view of the energy transfer mechanism between Eu2+ and Tb3+, the Ba3GdNa(PO4)3F:Eu2+, Tb3+ emission color can adjust from blue to green, and their chromatic coordinates (x, y) vary from (0.16, 0.135) to (0.254, 0.398). The critical distance was also calculated to be 16.90 Å. The above results indicate that the Ba3GdNa(PO4)3F: Eu2+, Tb3+ phosphors are a candidate for blue-green components in the application of n-UV w-LEDs.

  6. 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.

  7. Evidence of conduction-electron shielding of the crystal electric field of Tb sub x Gd sub 1 minus x Al sub 2 intermetallics

    SciTech Connect

    del Moral, A.; Joven, E. Instituto de Ciencio de Materiales de Aragon, Universidad de Zaragoza, Consejo Superior de Investigaciones Cientificas, Zaragoza )

    1990-12-01

    A comparison of the values obtained for the {ital B}{sub 4} crystal-electric-field (CEF) parameter in the series of cubic intermetallics Tb{sub {ital x}}Gd{sub 1{minus}{ital x}}Al{sub 2} with a model which predicts a dependence of {ital B}{sub 4} on the density of states with {ital d} character at the Fermi level, allows us to demonstrate directly the shielding effect of the conduction electrons on the CEF produced by the lattice of tripositive rare-earth and Al ions.

  8. Luminescence and energy transfer of the color-tunable phosphor Li₆Gd(BO₃)₃:Tb³⁺/Bi³⁺, Eu³⁺.

    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 275 nm, 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

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. Powder X-Ray Reference Patterns of Sr2RGaCu2Oy (R = Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, and Y)

    PubMed Central

    Wong-Ng, W.; Kaduk, J. A.; Levin, I.; Greenwood, W.; Dillingham, J.

    2001-01-01

    X-Ray Rietveld refinements were conducted on a series of eleven lanthanide phases, Sr2RGaCu2Oy (2112 phase, R = Pr, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, Tm, and Yb) that are structurally related to the high Tc superconductor Ba2YCu3O7 (213). In the 2112 structure, instead of square planar Cu-O chains, tetrahedral GaO4 chains were found to run in a zig-zag fashion along the diagonal of the basal 213 ab-direction. Reference powder patterns for these compounds were prepared by using the Rietveld decomposition technique. The unit cell volume of these compounds follows the expected trend of the lanthanide contraction. The lattice parameters range from a = 22.9694(3) Å, b = 5.5587(2) Å, and c = 5.44743(7) Å for R = Pr, to a = 22.8059(2) Å, b = 5.46031(5) Å, and c = 5.37773(5) Å for R = Yb. An electon diffraction study of the Sm- and Er-analogs showed characteristic diffuse streaks along the b-axis, suggesting some disorder within the GaO4 chains.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  19. 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.

  20. 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 .

  1. 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

  2. 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.

  3. 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

  4. Optical emission, vibrational feature, and shear-thinning aspect of Tb3+-doped Gd2O3 nanoparticle-based novel ferrofluids irradiated by gamma photons

    NASA Astrophysics Data System (ADS)

    Paul, Nibedita; Hazarika, Samiran; Saha, Abhijit; Mohanta, Dambarudhar

    2013-10-01

    The present work reports on the spectroscopic and rheological properties of un-exposed and gamma (γ-) irradiated rare earth (RE) oxide nanoparticle-based ferrofluids (FFs). The FFs were produced by dispersing surfactant coated terbium (Tb3+)-doped gadolinium oxide (Gd2O3) nanoparticles in the ethanol medium and later on they were subjected to energetic γ-irradiation (1.25 MeV) at select doses (97 Gy and 2.635 kGy). The synthesized RE oxide nanoparticles were of ˜7 nm size and having a cubic crystal structure, as predicted from transmission electron microscopy and x-ray diffraction studies. Fourier transformed infra-red (FT-IR) spectra showed an adequate blue shift of the Gd-O vibrational stretching mode from a wavenumber value of ˜558 cm-1, for the un-irradiated sample to a value of ˜540 cm-1 corresponding to the irradiated sample (2.635 kGy). In contrast, photoluminescence spectra have revealed modification of defect states along with Tb3+ assisted radiative transitions. The rheology measurements have illustrated unusual shear thinning behavior of the FFs, with an apparently improved power index (s) value from 0.34 to 0.50, obtained for increasing γ-dose cases. The variation of the decay parameter with irradiation dose, as predicted from the nature of apparent viscosity curves, is attributed to the defect formation, role of impurity ions (Tb3+), and weakening of inter nanoparticle bonding. The unusual properties of the novel RE oxide based FFs may find scope in sealing and shielding elements in the radiation environment including accelerator and other related zones.

  5. 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.

  6. 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.

  7. Magnetoelectric responses from the respective magnetic R and Fe subsystems in the noncentrosymmetric antiferromagnets RFe3(BO3)4 (R = Eu, Gd, and Tb)

    NASA Astrophysics Data System (ADS)

    Kurumaji, T.; Ohgushi, K.; Tokura, Y.

    2014-05-01

    In rare-earth (R) ferroborates, RFe3(BO3)4 with R = Eu, Gd, and Tb, the magnetoelectric (ME) responses appear to stem from both the antiferromagnetic order of the iron (Fe) spins and the magnetic moments on the R ions. We measured the electric polarization (P) along the a axis while rotating a magnetic field (H) around the a axis and found that the target compounds show mutually distinctive H-direction dependencies. EuFe3(BO3)4 (R = Eu) shows an almost constant spontaneous P with a slight modulation when H is slanted from the c axis. The H-angle (θH) dependence of the P can be described by a formula P =P0-Λsin2θH. As for GdFe3(BO3)4 and TbFe3(BO3)4, they show highly anisotropic θH dependence of P, which characterizes the respective ME responses from their R magnetic moments. In certain regions of θH, the P can be described by P =P0-Ksin2θH and P =P0∓ΓsinθH for R = Gd and Tb, respectively. We devised a theory for the ME response of the individual magnetic ions in a RFe3(BO3)4 crystal and applied it to these compounds focusing on their local symmetry and their ground-state multiplet structures. The above formulas successfully reproduce the observed results as the summation of P from each magnetic subsystem, which in turn enables us to assign the first and second terms to the spontaneous P due to a collinear antiferromagnetic ordering of the Fe spins and the ME response of the R ion under H, respectively. The thermal and H-induced evolutions of the magnetic-ion resolved P quantitatively agree with the theoretical predictions, ensuring the relevant microscopic ME mechanism for each magnetic ion. The measurement of angular dependence of P is particularly useful to decompose the overlapped ME responses into the respective origins in the system with multiple magnetic subsystems.

  8. Antiferromagnetic behaviour of Tb2Al alloy

    NASA Astrophysics Data System (ADS)

    Rojas, D. P.; André, G.; Rodríguez Fernández, J.; Sánchez Marcos, J.; Fernández Barquín, L.; Echevarria, C.

    2011-10-01

    The structural, thermal and magnetic properties ol the Tb2Al alloy have been investigated by AC/DC magnetic susceptibility, specific heat, X-ray and neutron diffraction measurements. DC and AC-magnetic susceptibility results are consistent with an AFM order at TN = 52 K. The specific heat data show a lambda anomaly associated to the magnetic transition with a peak at 52 K (cord = 99 J/molTbK). The analysis of thermodiffractograms of neutron diffraction patterns indicates that, below the ordering temperature, the magnetic reflections can be indexed with a commensurate lattice related to the crystallographic cell (Pmna) by a propagation vector k = (1/2, 1/2, 1/2). The results are compared with those reported for other magnetic rare earth alloys of R2Al-type (with R = Nd, Gd and Dy).

  9. Direct observation of lanthanide(III)-phthalocyanine molecules on Au(111) by using scanning tunneling microscopy and scanning tunneling spectroscopy and thin-film field-effect transistor properties of Tb(III)- and Dy(III)-phthalocyanine molecules.

    PubMed

    Katoh, Keiichi; Yoshida, Yusuke; Yamashita, Masahiro; Miyasaka, Hitoshi; Breedlove, Brian K; Kajiwara, Takashi; Takaishi, Shinya; Ishikawa, Naoto; Isshiki, Hironari; Zhang, Yan Feng; Komeda, Tadahiro; Yamagishi, Masakazu; Takeya, Jun

    2009-07-29

    The crystal structures of double-decker single molecule magnets (SMM) LnPc(2) (Ln = Tb(III) and Dy(III); Pc = phthalocyanine) and non-SMM YPc(2) were determined by using X-ray diffraction analysis. The compounds are isomorphous to each other. The compounds have metal centers (M = Tb(3+), Dy(3+), and Y(3+)) sandwiched by two Pc ligands via eight isoindole-nitrogen atoms in a square-antiprism fashion. The twist angle between the two Pc ligands is 41.4 degrees. Scanning tunneling microscopy was used to investigate the compounds adsorbed on a Au(111) surface, deposited by using the thermal evaporation in ultrahigh vacuum. Both MPc(2) with eight lobes and MPc with four lobes, which has lost one Pc ligand, were observed. In the scanning tunneling spectroscopy images of TbPc molecules at 4.8 K, a Kondo peak with a Kondo temperature (T(K)) of approximately 250 K was observed near the Fermi level (V = 0 V). On the other hand, DyPc, YPc, and MPc(2) exhibited no Kondo peak. To understand the observed Kondo effect, the energy splitting of sublevels in a crystal field should be taken into consideration. As the next step in our studies on the SMM/Kondo effect in Tb-Pc derivatives, we investigated the electronic transport properties of Ln-Pc molecules as the active layer in top- and bottom-contact thin-film organic field effect transistor devices. Tb-Pc molecule devices exhibit p-type semiconducting properties with a hole mobility (mu(H)) of approximately 10(-4) cm(2) V(-1) s(-1). Interestingly, the Dy-Pc based devices exhibited ambipolar semiconducting properties with an electron mobility (mu(e)) of approximately 10(-5) and a mu(H) of approximately 10(-4) cm(2) V(-1) s(-1). This behavior has important implications for the electronic structure of the molecules. PMID:19569681

  10. Experimental and Computational Analysis of Emission from Highly Ionized Si, Kr, Mo, Gd, and Tb Plasmas at 6.6 nm

    NASA Astrophysics Data System (ADS)

    Parchamy, Homaira; Szilagyi, John; Masnavi, Majid; Richardson, Martin; One Team

    2013-10-01

    There is increasing interest in high-power extreme-ultraviolet (EUV) laser-based lamps for sub-10 nm lithography operating in the region of 6.6 nm based on the LaN/B4C multilayer mirrors for manufacturing the next generation of microelectronics. A detailed multilevel non-LTE atomic model is developed to investigate emissivity and absorption properties of highly ionized Si, Kr, Mo, Gd, and Tb plasmas at 6.6 nm. Experimental spectra are presented together with analysis based on calculations using the relativistic Flexible Atomic Code. We will present the optimum regions for conversion efficiency of mass-limited targets against target density and laser parameters by means of 1D hydrodynamic coupled to a developed population kinetics codes.

  11. Collective phase-like mode and the role of lattice distortions at TN ˜ TC in RMn2O5 (R= Pr, Sm, Gd, Tb, Bi)

    NASA Astrophysics Data System (ADS)

    Massa, Néstor E.; García-Flores, Ali F.; De Sousa Meneses, Domingos; del Campo, Leire; Echegut, Patrick; Fabbris, Gilberto F. L.; Jesús Martínez-Lope, María; Alonso, José Antonio

    2012-05-01

    We report on electronic collective excitations in RMn2O5 (R =Pr, Sm, Gd, Tb) showing condensation starting at and below ˜ TN ˜ TC ˜ 40-50 K. Their origin is understood as partial delocalized eg electron orbitals in the Jahn-Teller distortion of the pyramid dimer with strong hybridized Mn3+-O bonds. Our local probes, Raman, infrared, and x-ray absorption, back the conclusion that there is no structural phase transition at TN ˜ TC. Ferroelectricity is magnetically assisted by electron localization triggering lattice polarizability by unscreening. We have also found phonon hardening as the rare earth is sequentially replaced. This is understood as a consequence of lanthanide contraction. It is suggested that partially f-electron screened rare earth nuclei might be introducing a perturbation to eg electrons prone to delocalize as the superexchange interaction takes place.

  12. Fabrication and characterization of pixelated Gd2O2S:Tb scintillator screens for digital X-ray imaging applications

    NASA Astrophysics Data System (ADS)

    Kim, Jongyul; Kyoung Cha, Bo; Hyung Bae, Jun; Lee, Chae-Hun; Kim, Hyungtaek; Chang, Sungho; Cho, Gyuseong; Sim, Cheulmuu; Kim, Taejoo

    2011-05-01

    X-ray imaging detectors in combination with scintillator screens have been widely used in digital X-ray imaging applications. Gd2O2S:Tb was used as scintillation material for pixelated scintillator screens based on silicon substrates (wafer) with a micropore array of various dimensions fabricated using the photolithography and deep reactive ion etching (DRIE) process. The relative light output and the modulation transfer function (MTF) of each fabricated scintillator screen were measured by a cooled CCD and compared with those of Lanex screens. The spatial resolution of our scintillator screens was higher but their light outputs were lower than those of Lanex screen probably due to the loss of light at the wall surfaces. Therefore further treatment of the wall surface, such as reflective coating, seems necessary to compensate the light loss.

  13. 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.

  14. 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.

  15. 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.

  16. Enhancement of Tb(III) -Cu(II) Single-Molecule Magnet Performance through Structural Modification.

    PubMed

    Heras Ojea, María José; Milway, Victoria A; Velmurugan, Gunasekaran; Thomas, Lynne H; Coles, Simon J; Wilson, Claire; Wernsdorfer, Wolfgang; Rajaraman, Gopalan; Murrie, Mark

    2016-08-26

    We report a series of 3d-4f complexes {Ln2 Cu3 (H3 L)2 Xn } (X=OAc(-) , Ln=Gd, Tb or X=NO3 (-) , Ln=Gd, Tb, Dy, Ho, Er) using the 2,2'-(propane-1,3-diyldiimino)bis[2-(hydroxylmethyl)propane-1,3-diol] (H6 L) pro-ligand. All complexes, except that in which Ln=Gd, show slow magnetic relaxation in zero applied dc field. A remarkable improvement of the energy barrier to reorientation of the magnetisation in the {Tb2 Cu3 (H3 L)2 Xn } complexes is seen by changing the auxiliary ligands (X=OAc(-) for NO3 (-) ). This leads to the largest reported relaxation barrier in zero applied dc field for a Tb/Cu-based single-molecule magnet. Ab initio CASSCF calculations performed on mononuclear Tb(III) models are employed to understand the increase in energy barrier and the calculations suggest that the difference stems from a change in the Tb(III) coordination environment (C4v versus Cs ). PMID:27484259

  17. 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

  18. 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.

  19. 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

  20. Nonlinear optical properties of pulsed laser deposited Gd2O3 and Dy2O3 doped K0.5Na0.5NbO3 thin films

    NASA Astrophysics Data System (ADS)

    Peddigari, Mahesh; Pattipaka, Srinivas; Bharti, Gyan Prakash; Khare, Alika; Dobbidi, Pamu

    2016-08-01

    We report the structural and nonlinear optical properties of Gd2O3 and Dy2O3 doped (K0.5Na0.5)NbO3 (KNN) lead-free thin films fabricated by pulsed laser deposition technique. The crystal structure of the films was analyzed by using Rietveld method. The higher tetragonality and improved surface morphology was observed for the rare-earth oxide doped films. The change in crystal structure and tetragonality with these dopants was explained in terms of change in the internal vibration modes of NbO6 octahedra. The nonlinear optical properties of the films were measured by using single beam Z-scan technique with a continuous wave He-Ne laser (λ = 632.8 nm). All the films have shown a large third-order nonlinear susceptibility and observed to be enhanced for rare-earth doped KNN thin films (|χ(3)| = 2.69 × 10-3 esu). The maximum nonlinear refractive index, n2 = 2.02 × 10-5 cm2/W, and nonlinear absorption coefficient, β = 3.48 cm/W, were obtained for Gd2O3, and Dy2O3 doped films respectively. These results indicate that rare-earth doped KNN thin films are potential candidates for nonlinear photonic applications.

  1. 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.

  2. 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.

  3. Polydentate-ligand-supported self-assembly of heterometallic T-shaped Co4RE (RE = Gd, Tb, Y) clusters: synthesis, structure and magnetism.

    PubMed

    Ke, Hongshan; Zhao, Lang; Guo, Yang; Tang, Jinkui

    2012-08-28

    A series of mixed-valent heterometallic pentanuclear Co(III)(3)Co(II)RE(III) (RE = Gd (1), Tb (2), Y (3)) clusters have been rationally assembled by taking advantage of a bifunctional ligand with o-vanillin and tripodal tris(hydroxymethyl)aminomethane units. Structural determinations reveal that all compounds are isomorphous and possess a T-shaped Co(4)RE core, which comprises two nearly linear Co(2)RE subunits sharing a common RE ion. Their magnetic properties were thoroughly studied. The static magnetic susceptibility studies of 1 demonstrate the presence of weak ferromagnetic interactions between the magnetic centres and magnetic anisotropy reflected by the single ion zero-field splitting (ZFS) D term. Both 1 and 2 behave magnetically as heterodinuclear metal systems, while the magnetic behaviour of 3 is identical to an isolated Co(II) ion. Moreover, alternating-current susceptibility measurements did not exhibit any out-of-phase signal, suggesting that slow magnetic relaxation is absent above 2 K within them. These isomorphous Co(4)RE clusters offer an opportunity to systematically probe the contribution of different metal ions to the overall magnetic behaviour in Co(II)-RE(III) systems. PMID:22767361

  4. Synthesis and spectroscopic properties of Yb3+ and Tb3+ co-doped GdBO3 materials showing down- and up-conversion luminescence.

    PubMed

    Grzyb, Tomasz; Kubasiewicz, Konrad; Szczeszak, Agata; Lis, Stefan

    2015-03-01

    Gadolinium orthoborates doped with Yb(3+) and Tb(3+) ions were synthesised by the sol-gel Pechini method. Materials annealed at 900 °C were composed of the monoclinic GdBO3 phase with micrometre-sized crystals. The structural properties of the products were analysed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The composition of the prepared materials was determined by inductively coupled plasma optical emission spectroscopy (ICP-OES). The materials showed intense ultraviolet (UV) or near infrared (NIR) excited green emission, which resulted from down- or up-conversion processes taking place in their structure. Spectroscopic properties were investigated on the basis of the measured excitation and emission spectra. Also, luminescence decays showing a short rise of emission with time after NIR excitation were measured. The dependence of the integral up-conversion intensity on the energy of the pumping laser was measured. The results indicated a two-photon process based on cooperative energy transfer (CET). The analysis of the synthesised series of samples allowed us to identify those with the best emission under a UV or NIR excitation source. PMID:25624052

  5. 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.

  6. Lattice distortions in layered type arsenides LnTAs 2 ( Ln=La-Nd, Sm, Gd, Tb; T=Ag, Au): Crystal structures, electronic and magnetic properties

    NASA Astrophysics Data System (ADS)

    Rutzinger, D.; Bartsch, C.; Doerr, M.; Rosner, H.; Neu, V.; Doert, Th.; Ruck, M.

    2010-03-01

    The lanthanide coinage-metal diarsenides LnTAs 2 ( Ln=La, Ce-Nd, Sm; T=Ag, Au) have been reinvestigated and their structures have been refined from single crystal X-ray data. Two different distortion variants of the HfCuSi 2 type are found: PrAgAs 2, NdAgAs 2, SmAgAs 2, GdAgAs 2, TbAgAs 2, NdAuAs 2 and SmAuAs 2 crystallize as twofold superstructures in space group Pmcn with the As atoms of their planar layers forming zigzag chains, whereas LaAgAs 2, CeAgAs 2 and PrAuAs 2 adopt a fourfold superstructure (space group Pmca) with cis-trans chains of As atoms. The respective atomic positions can be derived from the HfCuSi 2 type by group-subgroup relations. The compounds with zigzag chains of As atoms exhibit metallic behaviour while those with cis-trans chains are semiconducting as measured on powder pellets. The majority of the compounds including 4 f elements show antiferromagnetic ordering at TN<20 K.

  7. 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.

  8. Heat capacity, entropy of Ln2(MoO4)3 (Ln = La, Sm, and Gd), and the high-temperature enthalpy of Ln2(MoO4)3 (Ln = Eu, Dy, and Ho)

    NASA Astrophysics Data System (ADS)

    Lazarev, V. M.; Suponitskiy, Y. L.; Liashenko, S. E.

    2016-05-01

    The low-temperature heat capacity of Ln2(MoO4)3 (Ln = La, Sm, and Gd) is investigated by means of adiabatic calorimetry within the range of 60-300 K. The temperature dependences of the heat capacity are found and the values of the standard entropy are calculated, based on extrapolations to 0 K. Characteristic temperatures for molybdates are determined from the results of IR spectroscopic studies. The high-temperature enthalpy of Ln2(MoO4)3 (Ln = Eu, Dy, and Ho) is measured via high-temperature microcalorimetry, and the temperature dependence of heat capacity is calculated in the range of 298-1000 K. Since samarium and gadolinium molybdates are of the same structural type as terbium molybdate, we can estimate the anomaly of the heat capacity in the low-temperature region using the data for terbium molybdate and find the entropy of samarium and gadolinium molybdates.

  9. 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.

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

    SciTech Connect

    Cao Chunyan; 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.

  11. Crystal structure of ∼RCu3S3 and ∼RCuTe2 (R=Gd-Lu) compounds

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

    The crystal structures of ternary compounds TbCu3S3, Dy1.06Cu2.84S3 (space group R3¯), Ho0.67Cu2S2 (space group P3¯m1), ErCu3S3 (space group P3¯1c), Yb0.80Cu1.60S2, Lu0.67Cu2S2, TbCuTe2, DyCuTe2, Tm1.07Cu0.78Te2, LuCuTe2 (space group P3¯m1), Gd0.75Cu1.74Te2 (space group P3¯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 TbCuTe2 and DyCuTe2 crystallize as superstructure 2a×2a×2c to CaAl2Si2 structure type, whereas Gd0.75Cu1.74Te2, ErCu3S3 and TbCu3S3 (Dy1.06Cu2.84S3) have superstructure √3a×√3a×nc with n=1, 2, 3.

  12. Enhanced Ferroelectric Polarization by Induced Dy Spin Order in Multiferroic DyMnO{sub 3}

    SciTech Connect

    Prokhnenko, O.; Landsgesell, S.; Aliouane, N.; Argyriou, D. N.; Feyerherm, R.; Dudzik, E.

    2007-02-02

    Neutron powder diffraction and single crystal x-ray resonant magnetic scattering measurements suggest that Dy plays an active role in enhancing the ferroelectric polarization in multiferroic DyMnO{sub 3} above T{sub N}{sup Dy}=6.5 K. We observe the evolution of an incommensurate ordering of Dy moments with the same periodicity as the Mn spiral ordering. It closely tracks the evolution of the ferroelectric polarization. Below T{sub N}{sup Dy}, where Dy spins order commensurately, the polarization decreases to values similar for those of TbMnO{sub 3}. The higher P{sub s} found just above T{sub N}{sup Dy} arises from the contribution of Dy spins so as to effectively increase the amplitude of the Mn spin spiral.

  13. 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.

  14. Syntheses, structures, and properties of a series of novel high-nuclear 3d-4f clusters with mixed amino acids as ligands: {Ln6Cu24}(Ln = Gd, Tb, Pr and Sm).

    PubMed

    Shen, Chao-Jun; Hu, Sheng-Min; Sheng, Tian-Lu; Xue, Zhen-Zhen; Wu, Xin-Tao

    2015-04-14

    The first examples of high-nuclear 3d-4f heterometallic clusters with mixed amino acid ligands are reported. Four 30-nuclear clusters {Ln6Cu24}(Ln = Gd, Tb, Pr and Sm) were obtained through the self-assembly of Ln(III), Cu(II) and mixed amino acid ligands of glycine (HGly) and β-alanine (HAla). The metal skeleton of clusters may be described as a huge {Ln6Cu12} octahedron connected with 12 additional Cu(II) ions. The temperature dependence of magnetic susceptibilities of compounds were also studied. PMID:25756855

  15. 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

  16. 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

  17. Calculation of the phase diagrams of ferrimagnetic alloys A cB 1- c and application to transition metal-rare-earth Fe cGd 1- c and Fe cTb 1- c materials

    NASA Astrophysics Data System (ADS)

    Fresneau, M.; Virlouvet, A.; Khater, A.

    1999-07-01

    A theoretical model is presented for the calculation of the magnetic properties of generalised spin ferrimagnetic random substitutional alloys A cB 1- c with antiferromagnetic coupling between the A and B spin species. In particular, we study in an effective field method the phase diagrams of these systems as a function of the alloy concentration c, for given magnetic exchange constants. The model is applied with no adjustable parameters to the transition metal-rare-earth Fe cGd 1- c and Fe cTb 1- c alloys, using the appropriate spins for the Fe, Gd and Tb ions. We report a coherent and an overall qualitative agreement between theory and experiment in the complete range of concentrations 1⩾ c⩾0, for the first time to our knowledge, and determine consequently for these materials a set of ionic exchange constants that are invariant with respect to the alloy concentration. To our knowledge this is the first time that approximate but seemingly reliable exchange constants for the two alloys have been derived.

  18. 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.

  19. A-site size effect in a family of unfilled ferroelectric tetragonal tungsten bronzes: Ba₄R(0.67)Nb₁₀O₃₀ (R = La, Nd, Sm, Gd, Dy and Y).

    PubMed

    Gardner, Jonathan; Morrison, Finlay D

    2014-08-14

    The effect of A-cation size on the structural and electrical properties in a family of ferroelectric tetragonal tungsten bronzes (TTBs) Ba4R(0.67)□(1.33)Nb10O30 (R = La, Nd, Sm, Gd, Dy and Y; □ = vacancy) was investigated. In each case, the crystal structure, as determined from lab-based ambient powder X-ray diffraction (PXRD), is metrically tetragonal and can be refined in the P4bm space group. XRD data show an increased splitting of hk0 00l reflections with decreasing R cation size indicating an increasing tetragonal distortion (measured by tetragonality c/a). Dielectric data and ferroelectric measurements indicate that the ferroelectric Curie temperature, T(C), increases with decreasing R size and so a direct correlation between T(C) and tetragonality/ionic radius of R is demonstrated. Rietveld refinements show that the large A2-site is fully occupied by Ba(2+) and, in addition to the R cation size, the presence of vacancies at the A1-site (perovskite-like site) is also shown to strongly affect the stability of ferroelectricity in this structure type. PMID:24950736

  20. L-shell X-ray production cross sections of Ce, Nd, Sm, Eu, Gd, and Dy by impact of 14N2+ ions with energies between 7.0 MeV and 10.5 MeV

    NASA Astrophysics Data System (ADS)

    Murillo, G.; Méndez, B.; López-Monroy, J.; Miranda, J.; Villaseñor, P.

    2016-09-01

    L-shell X-ray production cross sections from the lanthanoid elements Ce, Nd, Sm, Eu, Gd, and Dy, induced by the impact of 14N2+ ions with energies in the interval 7.0 MeV to 10.5 MeV (0.50 MeV/μ to 0.75 MeV/μ), were measured and then compared with theoretical calculations obtained with the ECPSSR model with exact limits of integration (eCPSSR) and related corrections. These include the electron capture by the incoming ion and multiple ionizations of higher shells. Data from this work were contrasted with previously published L X-ray production cross sections for 14N2+ ion impact. As with other ions, a universal behavior is found when Lα and Lγ X-ray production cross sections are plotted as a function of reduced velocity parameters. The agreement with theoretical predictions was very good when the corrections were applied to the eCPSSR model.

  1. 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.

  2. 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

  3. Direct magnetoelectric effect in two-layer composite structures Tb0.12Dy0.2Fe0.68-PbZr0.53Ti0.47O3 at bending and longitudinal vibrations

    NASA Astrophysics Data System (ADS)

    Kalgin, A. V.; Gridnev, S. A.; Gribe, Z. H.

    2014-11-01

    The direct magnetoelectric effect has been studied in samples of two-layer composites containing 8 × 6 × 0.3-mm layers of the piezoelectric material PbZr0.53Ti0.47O3 and 6 × 6 × A-mm layers ( A = 0.3, 0.6, 0.9, 1.2, and 1.5) of the ferromagnet Tb0.12Dy0.2Fe0.68 and epoxy adhesive in the frequency range of 10-253 kHz at room temperature. It has been found that the magnetoelectric effect significantly increases at resonance frequencies (13.2-61.1 kHz) of the first harmonic of bending vibrations along the sample length, at resonance frequencies (39.5-90.7 kHz) of the first harmonic of bending vibrations along the sample width, and at resonance frequencies (123.3-141.0 kHz) of the first harmonic of longitudinal vibrations along the sample length. The magnetoelectric effect magnitudes at the resonance frequencies of the bending vibrations is found to be greater than that at the resonance frequencies of the longitudinal vibrations of the sample.

  4. 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

  5. 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

  6. 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

  7. Shape-controlled synthesis of well-defined matlockite LnOCl (Ln: La, Ce, Gd, Dy) nanocrystals by a novel non-hydrolytic approach.

    PubMed

    Kort, Kenneth R; Banerjee, Sarbajit

    2011-06-20

    We report here a novel synthetic route for the preparation of well-defined and faceted nanocrystals of ternary rare earth oxychlorides based on the ligand exchange and condensation of rare earth halides and alkoxides in the presence of coordinating solvents. Nanocubes, faceted 2D nanosheets, and nanodisk morphologies are obtained as a result of preferential growth along specific crystallographic directions dictated by the choice of the rare earth ion and the capping ligand. The synthetic approach reported here represents a unique low-temperature route for the preparation of LnOCl in the PbFCl matlockite phase. The synthetic strategy can further be adapted to incorporate dopant ions. The potential applicability of these nanostructures as phosphors is illustrated by demonstrating the upconversion of near-infrared illumination to green and red emission by Er(3+):GdOCl nanocrystals. PMID:21568295

  8. Tetranuclear lanthanide (III) complexes containing dimeric subunits: single-molecule magnet behavior for the Dy4 analogue.

    PubMed

    Chandrasekhar, Vadapalli; Das, Sourav; Dey, Atanu; Hossain, Sakiat; Sutter, Jean-Pascal

    2013-10-21

    The reaction of the lanthanide(III) salts [Dy(III), Tb(III), and Gd (III)] with a hetero donor chelating ligand N'-(2-hydroxy-3-methoxybenzylidene)-6-(hydroxymethyl) picolinohydrazide (LH3) and pivalic acid (PivH) in the presence of tetra-n-butylammonium hydroxide (TBAH) afforded the tetranuclear Ln(III) coordination compounds, [Ln4(LH)2(LH2)2(μ2-η(1)η(1)Piv)2(η(1)Piv)4]·2CHCl3 [Ln = Dy(1), Tb(2), and Gd(3)]. The molecular structure of these complexes reveals that the tetranuclear derivatives are composed of two dinuclear subunits which are interconnected through the coordination action of the picolinoyl hydrazine ligand. Within each subunit two different types of Ln(III) ions are present. One of these is eight-coordinate in a distorted triangular dodecahedral geometry while the other is nine-coordinate in a distorted spherical capped square antiprism geometry. Alternating current (ac) susceptibility measurements of complex 1 reveal a frequency- and temperature-dependent two step out-of-phase signals under 1kOe DC field which is characteristic of a single-molecule magnet (SMM) behavior. Analysis of the magnetic data afforded the anisotropic barriers and relaxation times: Δ/kB = 62.6 K, τ0 = 8.7 × 10(-7) s; Δ/kB = 26.3 K, τ0 = 1.26 × 10(-6) s for the slow and fast relaxations respectively. PMID:24111517

  9. 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

  10. TB Terms

    MedlinePlus

    ... Search The CDC Cancel Submit Search The CDC Tuberculosis (TB) Note: Javascript is disabled or is not ... message, please visit this page: About CDC.gov . Tuberculosis Basic TB Facts How TB Spreads Latent TB ...

  11. 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.

  12. New tetragonal derivatives of cubic NaZn13-type structure: RNi6Si6 compounds, crystal structure and magnetic ordering (R=Y, La, Ce, Sm, Gd-Yb)

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    Novel RNi6Si6 compounds adopt the new CeNi6Si6-type structure for R=La-Ce (tP52, space group P4/nbm N 125-1) and new YNi6Si6-type structure for R=Y, Sm, Gd-Yb (tP52, space group P4barb2N 117) that are tetragonal derivative of NaZn13-type structure, like LaCo9Si4-type. The CeNi6Si6, GdNi6Si6, TbNi6Si6, DyNi6Si6 and HoNi6Si6 compounds are Curie-Weiss paramagnets down to ~30 K, and do not order magnetically down to 5 K. However, the inverse paramagnetic susceptibility of LaNi6Si6 does not follow Curie-Weiss law. The DyNi6Si6 shows ferromagnetic-like saturation behaviour at 5 K in applied fields of 50 kOe, giving rise to a magnetic moment value of 6.5 μB/f.u. in 50 kOe. The powder neutron diffraction study in zero applied filed indicates square modulated the c-collinear antiferromagnetic ordering of TbNi6Si6 with K=[±1/4, ±1/4, 0] wave vector below ~10 K. The CeNi6Si6, GdNi6Si6, TbNi6Si6, DyNi6Si6 and HoNi6Si6 compounds are Curie-Weiss paramagnets down to ~30 K, and do not order magnetically down to 4.2 K. The powder neutron diffraction study in zero applied filed indicates square modulated the c-collinear antiferromagnetic ordering of TbNi6Si6 with K=[±1/4, ±1/4, 0] wave vector below ~10 K.

  13. 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

  14. 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

  15. Tuberculosis (TB)

    MedlinePlus

    ... Skip Content Marketing Share this: Main Content Area Tuberculosis (TB) Overview In developed countries, such as the ... thought to be infected with TB bacteria, Mycobacterium tuberculosis ( Mtb ). TB is a chronic bacterial infection. It ...

  16. A novel strategy to enhance the luminescence performance of NaGdF4:Ln(3+) nanocrystals.

    PubMed

    Song, Yan; Shao, Baiqi; Feng, Yang; Lü, Wei; Liu, Guixia; You, Hongpeng

    2016-06-21

    Promoting excitation efficiency is a direct route to enhance the luminescence properties of lanthanide doped materials. Here, we describe a novel strategy to enhance the luminescence performance of NaGdF4:Ln(3+) (Ln = Tb, Eu, Dy) nanoparticles by surface modification with benzoate (BA) and 1,10-phenanthroline (Phen) ligands via the sensitization of surface dopants. It was found that the surface ligands provide a new path for energy transfer to the activators due to the matching in energy levels between the two. Moreover, the overlap in excitation peaks for both Gd(3+) ions and ligands ensures the simultaneous energy transfer of Gd(3+)→ Ln(3+) and ligands → Ln(3+) under a single wavelength excitation. The obtained NaGdF4 nanocomposite was characterized in detail using XRD, FT-IR, TGA, SEM, and EDS. The luminescence performance of the surface modified NaGdF4:Ln(3+) nanoparticles was also optimized by tuning the loading amount of modified ligands. In addition, luminescence thermometry was realized by monitoring emission intensity at different temperatures. PMID:27188853

  17. 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

  18. 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.

  19. Tuberculosis (TB)

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  20. 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.

  1. 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.

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

    PubMed

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

    2011-09-01

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

  3. Hydrothermal synthesis, structure and optical properties of two novel 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

    Invited for the cover of this issue is the group of Hua Mei and Yan Xu at Nanjing Tech University, China. The image depicts star-like {Tb26 } clusters, which are simplified as blue balls, and Ag atoms, which are distributed in the MOF structure uniformly to give a lanthanide-MOF structure with good optical properties. Read the full text of the article at 10.1002/chem.201405178. PMID:25470812

  4. 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.

  5. An oxygen-sensitive luminescent Dy(iii) complex.

    PubMed

    Nakai, Hidetaka; Seo, Juncheol; Kitagawa, Kazuhiro; Goto, Takahiro; Matsumoto, Takahiro; Ogo, Seiji

    2016-06-21

    This paper presents the first dysprosium(iii) complex, [{((MeMe)ArO)3tacn}Dy(III)(THF)] (1(Dy)), that shows oxygen-sensitive luminescence. The synthesis, structure and oxygen-sensitive luminescence properties of 1(Dy) are reported (Φ = 0.050 and τ = 17.7 μs under N2, Φ = 0.011 and τ = 4.1 μs under O2 and KSV = 305 M(-1) in THF; KSV = 0.0077%(-1) in polystyrene film). The oxygen sensitive mechanism of 1(Dy) is discussed based on the photophysical properties of the corresponding gadolinium(iii) complex, [{((MeMe)ArO)3tacn}Gd(III)(THF)]. PMID:27191980

  6. The phase diagram and tetragonal superstructures of the rare earth cobaltate phases Ln1- xSr xCoO 3- δ ( Ln=La 3+, Pr 3+, Nd 3+, Sm 3+, Gd 3+, Y 3+, Ho 3+, Dy 3+, Er 3+, Tm 3+ and Yb 3+)

    NASA Astrophysics Data System (ADS)

    James, M.; Cassidy, D.; Goossens, D. J.; Withers, R. L.

    2004-06-01

    Single phase perovskite-based rare earth cobaltates ( Ln1- xSr xCoO 3- δ) ( Ln=La 3+, Pr 3+, Nd 3+, Sm 3+, Gd 3+, Dy 3+, Y 3+, Ho 3+, Er 3+, Tm 3+ and Yb 3+; 0.67⩽ x⩽0.9) have been synthesized at 1100°C under 1 atmosphere of oxygen. X-ray diffraction of phases containing the larger rare earth ions La 3+, Pr 3+ and Nd 3+ reveals simple cubic structures; however electron diffraction shows orientational twinning of a local, tetragonal ( I4/ mmm; ap× ap×2 ap) superstructure phase. Orientational twinning is also present for Ln1- xSr xCoO 3- δ compounds containing rare earth ions smaller than Nd 3+. These compounds show a modulated intermediate parent with a tetragonal superstructure ( I4/ mmm; 2 ap×2 ap×4 ap). Thermogravimetric measurements have determined the overall oxygen content, and these phases show mixed valence (3 +/4 +) cobalt oxidation states with up to 50% Co(IV). X-ray diffraction data and Rietveld techniques have been used to refine the structures of each of these tetragonal superstructure phases ( Ln=Sm 3+-Yb 3+). Coupled Ln/Sr and oxygen/vacancy ordering and associated structural relaxation are shown to be responsible for the observed superstructure.

  7. 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.

  8. Sulfate Exchange of the Nitrate-Type Layered Hydroxide Nanosheets of Ln2(OH)5NO3· nH2O for Better Dispersed and Multi-color Luminescent Ln2O3 Nanophosphors (Ln = Y0.98RE0.02, RE = Pr, Sm, Eu, Tb, Dy, Ho, Er, and Tm)

    NASA Astrophysics Data System (ADS)

    Wu, Xiaoli; Liu, Weigang; Li, Ji-Guang; Zhu, Qi; Li, Xiaodong; Sun, Xudong

    2016-07-01

    Through restricting thickness growth by performing coprecipitation at the freezing temperature of ~4 °C, solid-solution nanosheets (up to 5-nm thick) of the Ln2(OH)5NO3· nH2O layered hydroxide (Ln = Y0.98RE0.02; RE = Pr, Sm, Eu, Tb, Dy, Ho, Er, and Tm, respectively) were directly synthesized without performing conventional exfoliation. In situ exchange of the interlayer NO3 - with SO4 2- produced a sulfate derivative [Ln2(OH)5(SO4)0.5· nH2O] of the same layered structure and two-dimensional crystallite morphology but substantially contracted d 002 basal spacing (from ~0.886 to 0.841 nm). The sulfate derivative was systematically compared against its nitrate parent in terms of crystal structure and phase/morphology evolution upon heating. It is shown that the interlayer SO4 2-, owing to its bonding with the hydroxide main layer, significantly raises the decomposition temperature from ~600 to 1000 °C to yield remarkably better dispersed oxide nanopowders via a monoclinic Ln2O2SO4 intermediate. The resultant (Y0.98RE0.02)2O3 nanophosphors were studied for their photoluminescence to show that the emission color, depending on RE3+, spans a wide range in the Commission Internationale de l'Eclairage (CIE) chromaticity diagram, from blue to deep red via green, yellow, orange, and orange red.

  9. 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.

  10. 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

  11. Testing for TB Infection

    MedlinePlus

    ... Search The CDC Cancel Submit Search The CDC Tuberculosis (TB) Note: Javascript is disabled or is not ... message, please visit this page: About CDC.gov . Tuberculosis Basic TB Facts How TB Spreads Latent TB ...

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. Sulfate Exchange of the Nitrate-Type Layered Hydroxide Nanosheets of Ln2(OH)5NO3·nH2O for Better Dispersed and Multi-color Luminescent Ln2O3 Nanophosphors (Ln = Y0.98RE0.02, RE = Pr, Sm, Eu, Tb, Dy, Ho, Er, and Tm).

    PubMed

    Wu, Xiaoli; Liu, Weigang; Li, Ji-Guang; Zhu, Qi; Li, Xiaodong; Sun, Xudong

    2016-12-01

    Through restricting thickness growth by performing coprecipitation at the freezing temperature of ~4 °C, solid-solution nanosheets (up to 5-nm thick) of the Ln2(OH)5NO3·nH2O layered hydroxide (Ln = Y0.98RE0.02; RE = Pr, Sm, Eu, Tb, Dy, Ho, Er, and Tm, respectively) were directly synthesized without performing conventional exfoliation. In situ exchange of the interlayer NO3 (-) with SO4 (2-) produced a sulfate derivative [Ln2(OH)5(SO4)0.5·nH2O] of the same layered structure and two-dimensional crystallite morphology but substantially contracted d 002 basal spacing (from ~0.886 to 0.841 nm). The sulfate derivative was systematically compared against its nitrate parent in terms of crystal structure and phase/morphology evolution upon heating. It is shown that the interlayer SO4 (2-), owing to its bonding with the hydroxide main layer, significantly raises the decomposition temperature from ~600 to 1000 °C to yield remarkably better dispersed oxide nanopowders via a monoclinic Ln2O2SO4 intermediate. The resultant (Y0.98RE0.02)2O3 nanophosphors were studied for their photoluminescence to show that the emission color, depending on RE(3+), spans a wide range in the Commission Internationale de l'Eclairage (CIE) chromaticity diagram, from blue to deep red via green, yellow, orange, and orange red. PMID:27405467

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

    SciTech Connect

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

    1988-03-01

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

  19. 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

  20. 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

  1. A phosphorus-based compartmental ligand, (S)P[N(Me)N=CH-C6H3-2-O-3-OMe]3 (LH3), enables the assembly of luminescent heterobimetallic linear {L2Zn2Ln}+ [Ln = Gd, Tb, Nd and Eu] complexes.

    PubMed

    Chandrasekhar, Vadapalli; Bag, Prasenjit; Murugesapandian, Balasubramanian; Pandey, Mrituanjay D

    2013-11-21

    The sequential reaction of a phosphorus-based trishydrazone ligand, LH3 with anhydrous ZnCl2 and LnCl3·6H2O in a 2 : 2 : 1 stoichiometric ratio in the presence of triethylamine as the base leads to the formation of monocationic trinuclear complexes [L2Zn2Ln]Cl {Ln = Gd (1), Tb (2), Nd (3), Eu (4) and L = [(S)P[N(Me)N=CH-C6H3-2-O-3-OMe]3}. All the three metal ions, in each of these compounds, are arranged in a linear fashion. The two terminal Zn(II) ions are encapsulated by three imino and three phenolate oxygen atoms while the lanthanide ion remains in the centre with an all-oxygen coordination environment. Detailed photophysical measurements reveal the complete absence of antenna sensitization in all the four complexes. However, a strong emission was found for 2 and 4 when excited directly at their f-f levels. PMID:24018551

  2. New ternary rare-earth metal boride carbides R15B 4C 14 ( R=Y, Gd-Lu) containing BC 2 units: Crystal and electronic structures, magnetic properties

    NASA Astrophysics Data System (ADS)

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

    2010-10-01

    The ternary rare-earth boride carbides R15B 4C 14 ( R=Y, Gd-Lu) were prepared from the elements by arc-melting followed by annealing in silica tubes at 1270 K for 1 month. The crystal structures of Tb 15B 4C 14 and Er 15B 4C 14 were determined from single crystal X-ray diffraction data. They crystallize in a new structure type in space group P4/ mnc (Tb 15B 4C 14: a=8.1251(5) Å, c=15.861(1) Å, Z=2, R1=0.041 (w R2=0.088) for 1023 reflections with Io>2 σ( Io); Er 15B 4C 14: a=7.932(1) Å, c=15.685(2) Å, Z=2, R1=0.037 (w R2=0.094) for 1022 reflections with Io>2 σ( Io)). The crystal structure contains discrete carbon atoms and bent CBC units in octahedra and distorted bicapped square antiprisms, respectively. In both structures the same type of disorder exists. One R atom position needs to be refined as split atom position with a ratio 9:1 indicative of a 10% substitution of the neighboring C 4- by C 24-. The actual composition has then to be described as R15B 4C 14.2. The isoelectronic substitution does not change the electron partition of R15B 4C 14 which can be written as ( R3+) 15(C 4-) 6(CBC 5-) 4•e -. The electronic structure was studied with the extended Hückel method. The investigated compounds Tb 15B 4C 14, Dy 15B 4C 14 and Er 15B 4C 14 are hard ferromagnets with Curie temperatures TC=145, 120 and 50 K, respectively. The coercive field BC=3.15 T for Dy 15B 4C 14 is quite remarkable.

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

    PubMed

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

    2013-10-01

    A series of isostructural octanuclear lanthanide complexes of general formula [Ln8(sao)4(μ3-OH)4(NO3)12(DMF)12] (Ln = Nd (), Sm (), Eu (), Gd (), Tb (), Dy (), Ho (), Er (); DMF = dimethylformamide) have been prepared via reactions of salicylaldoxime (saoH2), tetramethylammonium hydroxide (Me4NOH) with the appropriate lanthanide nitrate salt (Ln(NO3)3·6H2O). The metallic skeletons of the complexes describe [Ln4] tetrahedra encapsulated inside a [Ln4] square with the inner core stabilised through μ3-OH(-) ions and the periphery by μ4-sao(2-) ligands. The magnetic properties of compounds were investigated by dc and ac magnetometry. Temperature dependent ac magnetic susceptibility data reveal that the dysprosium analogue () displays an out-of-phase signal in the absence of an applied magnetic field indicative of slow relaxation of the magnetization typical of a Single-Molecule Magnet (SMM). Micro-SQUID measurements reveal temperature and sweep rate dependent hysteresis below 1.0 K. PMID:23943045

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

    NASA Astrophysics Data System (ADS)

    Mioduski, Tomasz; 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.

  5. 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 Central

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

    2016-01-01

    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@CS0-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

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

    MedlinePlus

    ... Search The CDC Cancel Submit Search The CDC Tuberculosis (TB) Note: Javascript is disabled or is not ... message, please visit this page: About CDC.gov . Tuberculosis Basic TB Facts How TB Spreads Latent TB ...

  7. 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.

  8. 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

  9. Concerning the effect of certain admixtures on properties of LaOBr - Tb-luminophor

    SciTech Connect

    Golovkova, S.I.; Gurvich, A.M.; Kra, G.; Bel'shtedt, K.; Birman, T.A.; Katomina, R.V.

    1985-08-01

    It is shown that among lanthanides the most strong effect on the LaOBr - Tb X-ray phosphor luminescence is exerted by Ce (phosphorogen and sensitizer), Sm (luminescence killer), Eu and Yb (phosphorescence killers). The Nd, Dy, Tm, Yb, Fe and Ni impurities in concentration of about 10/sup -5/ g-atom/mol intensify the roentgenoluminescence of LaOBr - Tb. The luminescent-photographic method makes it possible to detect traces of radioactive impurities which accompany lanthanum.

  10. Questions and Answers about TB

    MedlinePlus

    ... Search The CDC Cancel Submit Search The CDC Tuberculosis (TB) Note: Javascript is disabled or is not ... message, please visit this page: About CDC.gov . Tuberculosis Basic TB Facts How TB Spreads Latent TB ...

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

    PubMed

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

    2011-10-17

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

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

    PubMed

    Zhang, Jiliang; Wang, Yingmin; Bobev, Svilen

    2015-02-01

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

  13. Fusion of {sup 6}Li with {sup 159}Tb at near-barrier energies

    SciTech Connect

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

    2011-06-15

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

  14. 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…

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  16. 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.

  17. 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.

  18. 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 ... Viral Hepatitis, STD, and TB Prevention Division of Tuberculosis Elimination

  19. Structure and photoluminescent properties of green-emitting terbium-doped GdV1-x Px O4 phosphor prepared by solution combustion method.

    PubMed

    Motloung, S J; Shaat, S K K; Tshabalala, K G; Ntwaeaborwa, O M

    2016-08-01

    Terbium-doped gadolinium orthovanadate (GdVO4 :Tb(3+) ), orthophosphate monohydrate (GdPO4 ·H2 O:Tb(3+) ) and orthovanadate-phosphate (GdV,PO4 :Tb(3+) ) powder phosphors were synthesized using a solution combustion method. X-Ray diffraction analysis confirmed the formation of crystalline GdVO4 , GdPO4 ·H2 O and GdV,PO4 . Scanning electron microscopy images showed that the powder was composed of an agglomeration of particles of different shapes, ranging from spherical to oval to wire-like structures. The chemical elements present were confirmed by energy dispersive spectroscopy, and the stretching mode frequencies were determined by Fourier transform infrared spectroscopy. UV-visible spectroscopy spectra showed a strong absorption band with a maximum at 200 nm assigned to the absorption of VO4 (3-) and minor excitation bands assigned to f → f transitions of Tb(3+) . Four characteristic emission peaks were observed at 491, 546, 588 and 623 nm, and are attributed to (5) D4  → (7) Fj (j = 6, 5, 4 and 3). The photoluminescent prominent green emission peak ((5) D4  → (7) F5 ) was centred at 546 nm. The structure and possible mechanism of light emission from GdV1-x Px O4 :% Tb(3+) are discussed. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26748674

  20. Competing magnetic phases and field-induced dynamics in DyRuAsO

    NASA Astrophysics Data System (ADS)

    McGuire, Michael A.; Garlea, V. Ovidiu; May, Andrew F.; Sales, Brian C.

    2014-07-01

    Analysis of neutron diffraction, dc magnetization, ac magnetic susceptibility, heat capacity, and electrical resistivity for DyRuAsO in an applied magnetic field are presented at temperatures near and below those at which the structural distortion (TS=25 K) and subsequent magnetic ordering (TN=10.5 K) take place. Powder neutron diffraction is used to determine the antiferromagnetic order of Dy moments of magnitude 7.6(1)μB in the absence of a magnetic field, and demonstrate the reorientation of the moments into a ferromagnetic configuration upon application of a magnetic field. Dy magnetism is identified as the driving force for the structural distortion. The magnetic structure of analogous TbRuAsO is also reported. Competition between the two magnetically ordered states in DyRuAsO is found to produce unusual physical properties in applied magnetic fields at low temperature. An additional phase transition near T*=3 K is observed in heat capacity and other properties in fields ≳3 T. Magnetic fields of this magnitude also induce spin-glass-like behavior including thermal and magnetic hysteresis, divergence of zero-field-cooled and field-cooled magnetization, frequency dependent anomalies in ac magnetic susceptibility, and slow relaxation of the magnetization. This is remarkable since DyRuAsO is a stoichiometric material with no disorder detected by neutron diffraction, and suggests analogies with spin-ice compounds and related materials with strong geometric frustration.

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

    PubMed

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

    2005-01-24

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

  2. Tuberculosis (TB): Treatment

    MedlinePlus

    ... Departments & Divisions Home Conditions Tuberculosis Treating Tuberculosis Treating Tuberculosis Make an Appointment Refer a Patient Ask a ... bones is treated longer. NEXT: Preventive Treatment Diagnosing Tuberculosis History of TB Our Specialists Charles L. Daley, ...

  3. TB Screening Tests

    MedlinePlus

    ... a risk that the first TST is a false-negative reaction, a second skin test is given ... species, for example Mycobacterium kansasii , will give a false-positive TST or IGRA result for TB. Positive ...

  4. 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.

  5. Unequivocal synthetic pathway to heterodinuclear (4f,4f') complexes: magnetic study of relevant (Ln(III), Gd(III)) and (Gd(III), Ln(III)) complexes.

    PubMed

    Costes, Jean-Pierre; Nicodème, Franck

    2002-08-01

    The tripodal ligand tris[4-(2-hydroxy-3-methoxyphenyl)-3-aza-3-buten]amine (LH(3)) is capable of coordinating to two different lanthanide ions to give complexes formulated as [LLnLn'(NO(3))(3)].x H(2)O. The stepwise synthetic procedure consists of introducing first a Ln(III) ion in the inner N(4)O(3) coordination site. The isolated neutral complex LLn is then allowed to react with a second and different Ln' ion that occupies the outer O(6) site, thus yielding a [LLnLn'(NO(3))(3)].x H(2)O complex. A FAB(+) study has confirmed the existence of (Ln, Ln') entities as genuine, when the Ln' ion in the outer site has a larger ionic radius than the Ln ion in the inner site. The qualitative magnetic study of the (Gd, Ln) and (Ln, Gd) complexes, based on the comparison of the magnetic properties of (Gd, Ln) (or (Ln, Gd)) pairs and (Y, Ln) (or (Ln, La)) pairs, is very informative. Indeed, these former complexes are governed by the thermal population of the Ln(III) Stark levels and the Ln-Gd interaction, while the latter are influenced by the thermal population of the Ln(III) Stark levels. We have been able to show that a ferromagnetic interaction exists at low temperature in the (Gd, Nd), (Gd, Ce), and (Yb, Gd) complexes. In contrast, an antiferromagnetic interaction occurs in the (Dy, Gd) and (Er, Gd) complexes. Although we cannot give a quantitative value to these interactions, we can affirm that their magnitudes are weak since they are only perceptible at very low temperature. PMID:12203324

  6. 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 ... Viral Hepatitis, STD, and TB Prevention Division of Tuberculosis Elimination TB Facts: You Can Prevent TB What ...

  7. 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 ...

  8. 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

  9. 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.

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

    PubMed

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

    2010-09-01

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

  11. 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/.

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

    SciTech Connect

    Vitaliy Vladislavovich Ivchenko

    2002-07-19

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

  13. A novel Ho 36Dy 20Al 24Co 20 bulk metallic glass with large magnetocaloric effect

    NASA Astrophysics Data System (ADS)

    Liang, L.; Hui, X.; Zhang, C. M.; Lu, Z. P.; Chen, G. L.

    2008-04-01

    A new heavy rare-earth-based Ho 36Dy 20Al 24Co 20 bulk metallic glass (BMG) has been prepared by a copper mold casting. A maximum magnetic entropy change of 11.77 J/kg K has been measured in Ho 36Dy 20Al 24Co 20 bulk metallic glass under a magnetic field of 5 Tesla, which is larger than that of the early reported Ho-based bulk metallic glass Ho 30Y 26Al 24Co 20. The half-maximum temperature range of the entropy change peak is as large as 40 K, leading to a superior refrigerant capacity to those of the Gd 5Si 2Ge 2 and Gd 5Si 2Ge 1.9Fe 0.1 crystalline compounds. The excellent magnetocaloric effect together with the unique properties of metallic glass makes this alloy a promising candidate for a magnetic refrigerant in the temperature range below 50 K.

  14. 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.

  15. Lifetime Measurements in 162Dy

    NASA Astrophysics Data System (ADS)

    Casarella, Clark; Aprahamian, A.; Lesher, S.; Crider, B.; Lowe, M.; Peters, E.; Prados-Estevez, F.; Ross, T.; Tully, Z.; Yates, S.

    2015-10-01

    Historically, the rare-earth region of nuclei has been a fountainhead for nuclear structure phenomena. One of the more debated structure effects is the nature of excited 0+ bands in nuclei, and continues to be an outstanding challenge in nuclear structure physics; several interpretations exist, and we hope that lifetime measurements can help distinguish between them. 162Dy has an abundance of 0+ states with limited lifetime data; we have measured excitation functions, mean lifetimes, and angular distributions of gamma rays for excited states in 162Dy at the University of Kentucky Accelerator Laboratory. Low lying excited states were populated up to an excitation energy of E < 3.2 MeV, where we will discuss the implications of the lifetimes under this energy threshold. This work was supported by the NSF under contract numbers PHY-1068192, PHY-1205412, and PHY-0956310.

  16. 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}.

  17. New ternary rare-earth metal boride carbides R{sub 15}B{sub 4}C{sub 14} (R=Y, Gd-Lu) containing BC{sub 2} units: Crystal and electronic structures, magnetic properties

    SciTech Connect

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

    2010-10-15

    The ternary rare-earth boride carbides R{sub 15}B{sub 4}C{sub 14} (R=Y, Gd-Lu) were prepared from the elements by arc-melting followed by annealing in silica tubes at 1270 K for 1 month. The crystal structures of Tb{sub 15}B{sub 4}C{sub 14} and Er{sub 15}B{sub 4}C{sub 14} were determined from single crystal X-ray diffraction data. They crystallize in a new structure type in space group P4/mnc (Tb{sub 15}B{sub 4}C{sub 14}: a=8.1251(5) A, c=15.861(1) A, Z=2, R{sub 1}=0.041 (wR{sub 2}=0.088) for 1023 reflections with I{sub o}>2{sigma}(I{sub o}); Er{sub 15}B{sub 4}C{sub 14}: a=7.932(1) A, c=15.685(2) A, Z=2, R{sub 1}=0.037 (wR{sub 2}=0.094) for 1022 reflections with I{sub o}>2{sigma}(I{sub o})). The crystal structure contains discrete carbon atoms and bent CBC units in octahedra and distorted bicapped square antiprisms, respectively. In both structures the same type of disorder exists. One R atom position needs to be refined as split atom position with a ratio 9:1 indicative of a 10% substitution of the neighboring C{sup 4-} by C{sub 2}{sup 4-}. The actual composition has then to be described as R{sub 15}B{sub 4}C{sub 14.2}. The isoelectronic substitution does not change the electron partition of R{sub 15}B{sub 4}C{sub 14} which can be written as (R{sup 3+}){sub 15}(C{sup 4-}){sub 6}(CBC{sup 5-}){sub 4{center_dot}}e{sup -}. The electronic structure was studied with the extended Hueckel method. The investigated compounds Tb{sub 15}B{sub 4}C{sub 14}, Dy{sub 15}B{sub 4}C{sub 14} and Er{sub 15}B{sub 4}C{sub 14} are hard ferromagnets with Curie temperatures T{sub C}=145, 120 and 50 K, respectively. The coercive field B{sub C}=3.15 T for Dy{sub 15}B{sub 4}C{sub 14} is quite remarkable. - Graphical abstract: The ternary rare earth boride carbides R{sub 15}B{sub 4}C{sub 14} (R=Y, Gd-Lu) were prepared from the elements by arc-melting followed by annealing in silica tubes at 1270 K for 1 month. Tb{sub 15}B{sub 4}C{sub 14} is a new member of the rare-earth metal boride carbide

  18. A planar triangular Dy3 + Dy3 single-molecule magnet with a toroidal magnetic moment.

    PubMed

    Li, Xiao-Lei; Wu, Jianfeng; Tang, Jinkui; Le Guennic, Boris; Shi, Wei; Cheng, Peng

    2016-07-21

    A unique Dy6 complex with a planar Dy3 + Dy3 structure was assembled by delicately modifying the axial ligands. Single-molecule magnet behavior and meanwhile a toroidal magnetic moment in the ground state have been observed. PMID:27388113

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

    PubMed

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

    2011-12-21

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

  20. 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.

  1. Magnetic structure of DyFe3

    NASA Astrophysics Data System (ADS)

    Jin, Long-huan; W, J. James; J, Rhyne; R, Lemaire

    1985-06-01

    Powder neutron diffraction measurements have been carried out on the intermetallic compound DyFe3 at 4 and 295K. The magnetic structure of the compound at 4 and 295K are noncollinear but coplanar in the a-c plane, and the moments of the Dy and Fe ions lie closer to the basal plane.

  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. 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.

  4. [166Dy]Dy/166Ho hydroxide macroaggregates: an in vivo generator system for radiation synovectomy.

    PubMed

    Ferro-Flores, G; Hernández-Oviedo, O; Arteaga de Murphy, C; Tendilla, J I; Monroy-Guzmán, F; Pedraza-López, M; Aldama-Alvarado, K

    2004-12-01

    Radiation synovectomy is an effective treatment in patients suffering from inflammatory-rheumatoid and degenerative joint diseases. The aim of this work was to examine the feasibility of preparing dysprosium-166 (166Dy)/holmium-166(166Ho) hydroxide macroaggregates ([166Dy]Dy/166Ho-HM) as an in vivo generator for radiation synovectomy evaluating whether the stability of 166Dy-HM and 166Ho-HM complexes is maintained when the daughter 166Ho is formed. The Monte Carlo (MCNP4B) theoretical depth dose profile for the in vivo [166Dy]Dy/166Ho generator system in a joint model was calculated and compared with that produced by 90Y, 153Sm and 166Ho. 166Dy was obtained by neutron irradiation of enriched 164Dy2O3 in a Triga Mark III reactor. Macroaggregates were prepared by reaction of [166Dy]DyCl3 with 0.5 M NaOH in an ultrasonic bath. [166Dy]Dy/166Ho-HM was obtained with radiochemical purity >99.5% and with the majority of particles in the 2-5 microm range. In vitro studies demonstrated that the radio-macroaggregates are stable in saline solution and human serum without a significant change in the particle size over 14 d, suggesting that no translocation of the daughter nucleus occurs subsequent to beta- decay of 166Dy. Biological studies in normal rats demonstrated high retention in the knee joint even 7 d after [166Dy]Dy/166Ho-HM administration. The Monte Carlo (MCNP4B) theoretical depth dose profiles in a joint model, showed that the in vivo [166Dy]Dy/166Ho generator system would produce 25% and 50% less radiation dose to the articular cartilage and bone surface, respectively, than that produced by 90Y or pure 166Ho in a treatment with the same therapeutic dose to the synovium surface. Despite that 153Sm showed the best depth dose profile sparing doses to healthy tissues, the use of 166Dy could provide the advantage of being applied in patients that cannot be reached within a few hours from a nuclear reactor and to produce less radiation exposure to the medical personnel

  5. U(IV)/Ln(III) mixed site in polymetallic oxalato complexes. Part III: Structure of Na[Yb(C 2O 4) 2(H 2O)]·3H 2O and the derived quadratic series (NH 4+) 1-x[ Ln1-xU x (C 2O 4) 2(H 2O)]·(3+ x) H 2O, Ln=Y, Pr-Sm, Gd, Tb

    NASA Astrophysics Data System (ADS)

    Chapelet-Arab, B.; Duvieubourg, L.; Nowogrocki, G.; Abraham, F.; Grandjean, S.

    2006-12-01

    Single crystals of a new sodium ytterbium oxalate Na[Yb(C 2O 4) 2(H 2O)]·3H 2O ( 1) and six mixed lanthanide (III)-uranium (IV) oxalates (NH 4+) 1-x[ Ln1-xU x (C 2O 4) 2(H 2O)]·(3+ x) H 2O, Ln=Y, x=0.47 ( 2), Ln=Pr, x=0.42 ( 3), Ln=Nd, x=0.60 ( 4), Ln=Sm, x=0.55 ( 5), Ln=Gd, x=0.25 ( 6) and Ln=Tb, x=0.52 ( 7) have been grown using slow diffusion through silica gels. The crystal structures of all the compounds have been determined by single-crystal X-ray diffraction. For compound 1 the symmetry is monoclinic, space group Pc, cell dimensions a=8.559(2) Å, b=8.564(2) Å, c=14.938(3) Å, β=103.062(3), Z=4. The structure of 1 is isotypic with Na[Y(C 2O 4) 2(H 2O)]·3H 2O and consists of layers formed by four-membered rings of Yb connected through oxalate ions. The ytterbium atom is nine-coordinated by oxygen from four bis-bidentate oxalate ligands and one water molecule which alternate up and down the layer. Na + ions and supplementary water molecules are located between the layers. The six mixed lanthanide (III)-uranium (IV) oxalates, 2- 7, are isotypic, the symmetry is tetragonal, space group P4/ n, the unit cell parameters are in the range 8.7239(12)-8.9116(6) and 7.854(2)-7.9487(9) Å for a and c, respectively, Z=2. The structure of the six compounds is built from the same two-dimensional arrangement of alternating metallic and oxalate ions forming four-membered rings. The layers are similar to that observed in 1 and the mixed Ln(III)/U(IV) oxalate layers are obtained by partial substitution of Ln(III) by U(IV) in a nine-coordinated site, the charge surplus being compensated by removal of monovalent cations in the interlayer space. The ammonium ions and the water molecules are disordered in the same crystallographic site. Thus these compounds form the third series of mixed lanthanide (III)-uranium (IV) oxalates, the tetragonal one, that completes the two others previously reported, the hexagonal and the triclinic series.

  6. Difference Between Latent TB Infection and Active TB Disease

    MedlinePlus

    ... ray, or positive sputum smear or culture • • Has active TB bacteria in his/her body • • Usually feels sick and may have symptoms such as coughing, fever, and weight loss • • May spread TB bacteria to others • • Needs treatment to treat ...

  7. 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.

  8. 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

  9. 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.

  10. Superdeformation studies in {sup 150}Tb and {sup 153}Ho

    SciTech Connect

    Nisius, D.; Janssens, R.V.F.; Crowell, B.

    1995-08-01

    There are now over 40 superdeformed (SD) bands known in the A {approximately} 150 region and in most cases the properties of these bands are understood in terms of single-particle excitations in the absence of pairing. By continuing the search for new SD bands we hope to gain insight into (1) the ordering of the proton and neutron orbitals near the Fermi surface in the SD well, (2) the effects that the alignment of those orbitals has on the moments of inertia, and (3) the collective excitations in the SD well. For {sup 150}Tb, which is one proton and one neutron away from the SD doubly-magic nucleus {sup 152}Dy, it should be possible to study SD bands based on both proton and neutron hole excitations. By adding one proton to the {sup 152}Dy nucleus (i.e. {sup 153}Ho) proton excitations above the Z = 66 shell gap can be studied. These excitations are important as calculations suggested that the proton intruder orbital N = 7 might become occupied. Interactions between this orbital and a N = 5 level may result in softness towards octupole vibrations. High spin states in {sup 150}Th and {sup 153}Ho were populated using the {sup 124}Sn({sup 31}P,5n) and {sup 120}Sn({sup 37}Cl,4n) reactions, respectively. In both cases the early implementation phase of Gammasphere was used to detect the decay gamma rays and over 1 x 10{sup 9} triple and higher fold coincidence events were recorded. In {sup 150}Tb, the data analysis is complete and two new SD bands were identified. The fact that Im{sup (2)} moments of inertia are sensitive to the specific high-N intruder content of the SD bands was used to suggest configurations for the two new bands. A paper reporting these results is being prepared. For {sup 153}Ho, data analysis is still in its early stages.

  11. 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

  12. 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

  13. 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

  14. Unique Y-shaped lanthanide aggregates and single-molecule magnet behaviour for the Dy4 analogue.

    PubMed

    Xue, Shufang; Guo, Yun-Nan; Zhao, Lang; Zhang, Peng; Tang, Jinkui

    2014-01-28

    The assembly of N'-(amino-(pyrimidin-2-yl)methylene)-o-vanilloyl hydrazine ligands (H2L, Scheme 1) with different lanthanide perchlorates produces novel Y-shaped tetranuclear complexes, [Ln4(μ3-OH)(L(2-))4(H2O)6]·(ClO4)3·6H2O, where Ln = Tb (1), Dy (2) and Ho (3). The formation of this unprecedented Y-shaped topology is largely ascribed to the versatility of the mixed-donor hydrazone ligands in terms of their potential denticity. Analysis of the susceptibility data shows that only the Dy-based molecule features SMM-like behaviour. The synthetic methodology of employing H2L and related ligands has provided a very promising route towards new families of magnetic coordination clusters with novel metal topologies and properties. PMID:24213812

  15. 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.

  16. Manipulation of Dy-Mn coupling and ferrielectric phase diagram of DyMn2O5: The effect of Y substitution of Dy

    NASA Astrophysics Data System (ADS)

    Zhao, Z. Y.; Wang, Y. L.; Lin, L.; Liu, M. F.; Li, X.; Yan, Z. B.; Liu, J.-M.

    2015-11-01

    DyMn2O5 is an extraordinary example in the family of multiferroic manganites and it accommodates both the 4f and 3d magnetic ions with strong Dy-Mn (4f-3d) coupling. The electric polarization origin is believed to arise not only from the Mn spin interactions but also from the Dy-Mn coupling. Starting from proposed scenario on ferrielectricity in DyMn2O5 where the exchange-strictions associated with the Mn3+-Mn4+-Mn3+ blocks and Dy3+-Mn4+-Dy3+ blocks generate the two ferroelectric sublattices, we perform a set of characterizations on the structure, magnetism, and electric polarization of Dy1-xYxMn2O5 in order to investigate the roles of Dy-Mn coupling in manipulating the ferrielectricity. It is revealed that the non-magnetic Y substitution of Dy suppresses gradually the Dy3+ spin ordering and the Dy-Mn coupling. Consequently, the ferroelectric sublattice generated by the exchange striction associated with the Dy3+-Mn4+-Dy3+ blocks is destabilized, but the ferroelectric sublattice generated by the exchange striction associated with the Mn3+-Mn4+-Mn3+ blocks remains less perturbed, enabling the ferrielectricity-ferroelectricity transitions with the Y substitution. A phenomenological ferrielectric domain model is suggested to explain the polarization reversal induced by the Y substitution. The present work presents a possible scenario of the multiferroic mechanism in not only DyMn2O5 but probably also other RMn2O5 members with strong 4f-3d coupling.

  17. Manipulation of Dy-Mn coupling and ferrielectric phase diagram of DyMn{sub 2}O{sub 5}: The effect of Y substitution of Dy

    SciTech Connect

    Zhao, Z. Y.; Wang, Y. L.; Lin, L.; Liu, M. F.; Li, X.; Yan, Z. B.; Liu, J.-M.

    2015-11-07

    DyMn{sub 2}O{sub 5} is an extraordinary example in the family of multiferroic manganites and it accommodates both the 4f and 3d magnetic ions with strong Dy-Mn (4f-3d) coupling. The electric polarization origin is believed to arise not only from the Mn spin interactions but also from the Dy-Mn coupling. Starting from proposed scenario on ferrielectricity in DyMn{sub 2}O{sub 5} where the exchange-strictions associated with the Mn{sup 3+}-Mn{sup 4+}-Mn{sup 3+} blocks and Dy{sup 3+}-Mn{sup 4+}-Dy{sup 3+} blocks generate the two ferroelectric sublattices, we perform a set of characterizations on the structure, magnetism, and electric polarization of Dy{sub 1-x}Y{sub x}Mn{sub 2}O{sub 5} in order to investigate the roles of Dy-Mn coupling in manipulating the ferrielectricity. It is revealed that the non-magnetic Y substitution of Dy suppresses gradually the Dy{sup 3+} spin ordering and the Dy-Mn coupling. Consequently, the ferroelectric sublattice generated by the exchange striction associated with the Dy{sup 3+}-Mn{sup 4+}-Dy{sup 3+} blocks is destabilized, but the ferroelectric sublattice generated by the exchange striction associated with the Mn{sup 3+}-Mn{sup 4+}-Mn{sup 3+} blocks remains less perturbed, enabling the ferrielectricity-ferroelectricity transitions with the Y substitution. A phenomenological ferrielectric domain model is suggested to explain the polarization reversal induced by the Y substitution. The present work presents a possible scenario of the multiferroic mechanism in not only DyMn{sub 2}O{sub 5} but probably also other RMn{sub 2}O{sub 5} members with strong 4f-3d coupling.

  18. Electromagnetic transition strengths in {sup 156}Dy

    SciTech Connect

    Moeller, O.; Dewald, A.; Saha, B.; Fitzler, A.; Jessen, K.; Klug, T.; Heinze, S.; Jolie, J.; Brentano, P. von; Petkov, P.; Tonev, D.; Bazzacco, D.; Ur, C. A.; Lunardi, S.; Farnea, E.; Axiotis, M.; Angelis, G. de; Napoli, D. R.; Marginean, N.; Martinez, T.

    2006-08-15

    Reliable and precise lifetimes of excited states in {sup 156}Dy 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 {sup 124}Sn({sup 36}S,4n){sup 156}Dy 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 {sup 156}Dy 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 {sup 156}Dy, the {gamma} 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({beta},{gamma}) may also be a reason for the differences in the spectroscopic properties of {sup 156}Dy and those nuclei.

  19. Magnetic reversal in Dy-doped DyF e2/YF e2 superlattice films

    NASA Astrophysics Data System (ADS)

    Stenning, G. B. G.; Bowden, G. J.; de Groot, P. A. J.; van der Laan, G.; Figueroa, A. I.; Bencok, P.; Steadman, P.; Hesjedal, T.

    2015-03-01

    Reversible magnetic exchange springs can be formed in the magnetically soft YF e2 layers of epitaxial DyF e2/YF e2 multilayer films. Here we show that the insertion of just two monolayers of DyF e2 , placed directly in the middle of the YF e2 layers, brings about substantial changes. Results are presented for a Dy-doped (110)-oriented [DyFe2(60Å) /YFe2(120 Å ) /DyFe2(8 Å ) /YFe2(120 Å ) ] 15 multilayer film, measured at 100 K in fields of up to ±10 T. Using bulk magnetometry, micromagnetic modeling, and Dy-specific x-ray magnetic circular dichroism, it is shown that Dy doping substantially increases the number of spin states available to the system. Altogether 12 distinct spring states are identified which bring additional complexity to the magnetic reversal process. In particular, the exchange springs are no longer reversible, exhibiting magnetic exchange-spring collapse. Full and partial magnetic loops are presented for fields applied along the in-plane easy [001] axis and the in-plane hard [1 ¯10 ] axis. In particular, it is demonstrated that exchange-spring collapse is sharpest when the field is applied along a hard in-plane [1 ¯10 ] axis.

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

    MedlinePlus

    ... Skip Content Marketing Share this: Main Content Area Tuberculosis Drugs First-Line Treatment of TB for Drug- ... ago. See how these drugs work . Multidrug-Resistant Tuberculosis (MDR TB) and Second-Line Treatments MDR TB ...

  1. Decay-out of 151Tb Yrast Superdeformed Band and Shape Coexistence

    SciTech Connect

    Duchene, G.; Robin, J.; Odahara, A.; Byrski, Th.; Beck, F.A.; Bednarczyk, P.; Curien, D.; Courtin, S.; Dorvaux, O.; Gall, B.; Joshi, P.; Nourreddine, A.; Pachoud, E.; Piqueras, I.; Vivien, J.P.; Twin, P.J.; Cullen, D.M.; Ertueck, S.; King, S.L.; Paul, E.S.

    2004-02-27

    Linking transitions between the superdeformed (SD) and the normal deformed (ND) wells have been searched in 151Tb nucleus. Two experiments of 5 and 17 days have been performed with EUROBALL IV. Transitions of 2818 keV and 3748 keV with intensities of about 1 % relative to the yrast SD band have been observed. Their decay-out properties are discussed in the text. In addition the eight known SD bands have been extended towards higher rotational frequencies where orbital crossings are observed. For the first time, weakly populated collective ND structures, likely triaxial, similar to the ones recently identified in 152Dy, 153Ho and 155Er nuclei have been observed in 151Tb. The SD and ND structures are interpreted in the frame of Woods-Saxon theoretical calculations.

  2. Electromagnetic transition strengths in 155Dy

    NASA Astrophysics Data System (ADS)

    Yavahchova, M. S.; Petkov, P.; Dewald, A.; Möller, O.; Saha, B.; Fitzler, A.; Jessen, K.; Tonev, D.; Gutev, N.; Klug, T.; Heinze, S.; Jolie, J.; von Brentano, P.; Bazzacco, D.; Ur, C.; Farnea, E.; Axiotis, M.; Lunardi, S.; Rossi-Alvarez, C.; de Angelis, G.; Napoli, D. R.; Marginean, N.; Martinez, T.; Caprio, M.

    2012-05-01

    Lifetimes of excited states in 155Dy 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 plunger using the reaction 124Sn(36S,5n)155Dy at a beam energy of 155 MeV. The Differential decay-curve method was applied for the lifetime determination. The measured transition probabilities in 155Dy and the energy spectrum are compared to the predictions of the Particle plus rotor model. The comparison indicates slightly different quadrupole deformations characterizing the low-lying one-quasineutron bands which may point to a shape coexistence.

  3. 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.

  4. 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

  5. Extensively Drug-Resistant Tuberculosis (XDR TB)

    MedlinePlus

    ... other federal agencies and international partners to raise awareness and enhance strategies for TB prevention worldwide by: Strengthening TB services for people living with HIV/AIDS; Guiding preparedness and outbreak investigation responses; Improving ...

  6. TB in Children in the United States

    MedlinePlus

    ... Statistics Related Links TB in Children in the United States TB disease in children under 15 years ... BCG vaccine is not generally used in the United States, because of the low risk of infection ...

  7. Commensurate Dy magnetic ordering associated with incommensurate lattice distortion in multiferroic DyMnO{sub 3}

    SciTech Connect

    Feyerherm, R.; Dudzik, E.

    2006-05-01

    Synchrotron x-ray diffraction and resonant magnetic scattering experiments on a single crystal of orthorhombic DyMnO{sub 3} have been carried out between 4 and 40 K. Below T{sub N}{sup Dy}=5 K, the Dy magnetic moments order in a commensurate structure with propagation vector 0.5 b{sup *}. Simultaneous with the Dy magnetic ordering, an incommensurate lattice modulation with propagation vector 0.905 b{sup *} evolves while the original Mn induced modulation is suppressed and shifts from 0.78 b{sup *} to 0.81 b{sup *}. This points to a strong interference of Mn and Dy induced structural distortions in DyMnO{sub 3} besides a magnetic coupling between the Mn and Dy magnetic moments.

  8. 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.

  9. 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.

  10. 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.

  11. Rare-earth chromium gallides RE4CrGa12 (RE=Tb-Tm)

    NASA Astrophysics Data System (ADS)

    Slater, Brianna R.; Bie, Haiying; Stoyko, Stanislav S.; Bauer, Eric D.; Thompson, Joe D.; Mar, Arthur

    2012-12-01

    The ternary rare-earth-metal chromium gallides RE4CrGa12 (RE=Tb-Tm) have been prepared by reactions of the elements at 1000 °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 Ga6 octahedral clusters found in the parent binary gallides REGa3 (AuCu3-type), although single-crystal X-ray diffraction studies suggest that complex superstructures may be adopted. An ideal ordered Y4PdGa12-type structure was successfully refined for a crystal of Dy4CrGa12 (Pearson symbol cI34, space group Im3barm, Z=2, a=8.572(1) Å). Magnetic measurements on single-crystal samples reveal ferromagnetic or possibly ferrimagnetic ordering for the Tb, Dy, and Er members (TC=22, 15, and 2.8 K, respectively) and antiferromagnetic ordering for the Ho member (TN=7.5 K). Band structure calculations on a hypothetical “Y4CrGa12” model suggest that the Cr atoms carry no local magnetic moment.

  12. 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)

  13. 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.

  14. Epitaxial growth and characterization of DyP/GaAs, DyAs/GaAs, and GaAs/DyP/GaAs heterostructures

    NASA Astrophysics Data System (ADS)

    Lee, P. P.; Hwu, R. J.; Sadwick, L. P.; Balasubramaniam, H.; Kumar, B. R.; Alvis, R.; Lareau, R. T.; Wood, M. C.

    1998-05-01

    There is a significant interest in the area of improving high temperature stable contacts to III-V semiconductors. Two attractive material systems that offer promise in this area are dysprosium phosphide/gallium arsenide (DyP/GaAs) and dysprosium arsenide/gallium arsenide (DyAs/GaAs). Details of epitaxial growth of DyP/GaAs and DyAs/GaAs by molecular beam epitaxy (MBE), and their characterization by x-ray diffraction, transmission electron microscopy, atomic force microscopy, Auger electron spectroscopy, Hall measurements, and high temperature current-voltage measurements is reported. DyP is lattice matched to GaAs, with a room temperature mismatch of less than 0.01% and is stable in air with no sign of oxidation, even after months of ambient exposure. Both DyP and DyAs have been grown by solid source MBE using custom designed group V thermal cracker cells and group III high temperature effusion cells. High quality DyP and DyAs epilayer were consistently obtained for growth temperatures ranging from 500 to 600°C with growth rates between 0.5 and 0.7 µm/h. DyP epilayers are n-type with electron concentrations of 3 × 1020 to 4 × 1020 cm-3, room temperature mobilities of 250 to 300 cm2/V·s, and a barrier height of 0.81 eV to GaAs. DyAs epilayers are also n-type with carrier concentrations of 1 × 1021 to 2 × 1021 cm-3, and mobilities between 25 and 40 cm2/V·s.

  15. Magnetic and microstructural modification of the Nd-Fe-B sintered magnet by mixed DyF3/DyHx powder doping

    NASA Astrophysics Data System (ADS)

    Kim, Tae-Hoon; Lee, Seong-Rae; Kim, Hyo-Jun; Lee, Min-Woo; Jang, Tae-Suk

    2014-05-01

    We investigated the magnetic and microstructural properties of Nd-Fe-B sintered magnets doped with DyF3, DyHx, and a mixture of DyF3 and DyHx powders. In the DyHx-doped magnet, diffusion of Dy occurs predominantly via grain boundary diffusion. However, the proportion of Dy being diffused by lattice diffusion is increased in the DyF3-doped magnet due to the different influences of F- and H+ ions. The detailed mechanism of the microstructural changes in terms of the diffusional behavior of Dy induced by the DyF3 and DyHx powder doping is discussed. The formation of a Dy-segregated Nd-rich oxide phase (RE-rich, Dy-Nd-O) was suppressed only in the DyF3-doped magnet, and the (00L) alignment of Nd2Fe14B grains in the sintered magnet increased when it was doped with the DyHx powder. We obtained the optimum microstructural and magnetic properties of the Nd-Fe-B sintered magnet through doping with a mixture of DyF3 and DyHx powders, which compensated for the drawbacks of using each powder alone.

  16. Energy transport in photoexcited crystals of K3[Tb(C2O4)3(H2O)].2H2O: Transfer from Tb3+ to Nd3+ and Eu3+

    NASA Astrophysics Data System (ADS)

    Kahwa, Ishenkumba A.; Parkes, Charmaine C.; McPherson, Gary L.

    1995-10-01

    The luminescence decay dynamics of Tb3+(5D4) and Eu(5D0) in triclinic (P1¯) crystalline K3[Ln(C2O4)3(H2O)].2H2O solids was studied between 10 and 298 K in order to establish the energy-transport characteristics. The luminescence decay rate of Tb3+ (740 s-1 for Ln=Tb3+) is temperature independent for the pure terbium complex; with introduction of Ln3+ dopants (e.g., Ln=Nd, Eu) faster decay rates which are temperature dependent are obtained. For the Eu3+ dopant, excitation buildup on the Eu3+(5D0) decay curve upon Tb3+(5D4) excitation confirms that energy transfer from Tb3+(5D4) to Ln3+ is active. The temperature dependence of the energy-transfer process in the K3[Eu0.83Tb0.17(C2O4)3(H2O)].2H2O mixed complex is well described by a relatively simple empirical expression based on Boltzmann's statistical dynamics of Eu3+ electronic energy among the 7FJ (J=0,1,2) terms. The limiting Eu3+-Tb3+ transfer rates are ~5.4×103 and 5.3×104 s-1 at 77 and 298 K, respectively. Energy migration on the terbium sublattice was confirmed by comparing Huber's [Phys. Rev. B 20, 2707 (1979)] trapping functions for K3[Eu0.4Tb0.6(C2O4)3(H2O)].2H2O and K3[Eu0.4Tb0.1Gd0.5(C2O4)3(H2O)].2H2O (Gd3+ serving as a scatterer for Tb3+ excitation). Although the structure of the complexes features a one-dimensional zigzag array of Ln3+ ions, energy transport is diffusive and not one dimensional.

  17. Labeling of biotin with [166Dy]Dy/166Ho as a stable in vivo generator system.

    PubMed

    Ferro-Flores, G; Arteaga de Murphy, C; Pedraza-López, M; Monroy-Guzmán, F; Meléndez-Alafort, L; Tendilla, J I; Jiménez-Varela, R

    2003-04-14

    The aim of this work was to synthesize [166Dy]Dy/166Ho-DTPA-Biotin to evaluate its potential as a new radiopharmaceutical for targeted radiotherapy. Dysprosium-166 (166Dy) was obtained by neutron irradiation of enriched 164Dy(2)O(3) in a Triga Mark III reactor. The labeling was carried out in aqueous media at pH 8.0 by addition of [166Dy]DyCl(3) to diethylenetriaminepentaacetic-alpha,omega-bis(biocytinamide) (DTPA-Biotin). Radiochemical purity was determined by high-performance liquid chromatography (HPLC) and TLC. The biological integrity of labeled biotin was studied evaluating its avidity for avidin in an agarose column and by size-exclusion HPLC analysis of the radiolabeled DTPA-Biotin with and without the addition of avidin. Stability studies against dilution were carried out by diluting the radiocomplex solution with saline solution and with human serum at 37 degrees C for 24 h. The [166Dy]Dy/166Ho-labeled biotin was obtained with a 99.1+/-0.6% radiochemical purity. In vitro studies demonstrated that [166Dy]Dy/166Ho-DTPA-Biotin is stable after dilution in saline and in human serum and no translocation of the daughter nucleus occurs subsequent to beta(-) decay of 166Dy that could produce release of 166Ho(3+). Avidity of labeled biotin for avidin was not affected by the labeling procedure. Biodistribution studies in normal mice showed that the [166Dy]Dy/166Ho-DTPA-Biotin has a high renal clearance. In conclusion, the radiolabeled biotin prepared in this investigation has adequate properties to work as a stable in vivo generator system for targeted radiotherapy. PMID:12672609

  18. 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.

  19. 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.

  20. Thermochromism and fluorescence in dyed PEO films

    SciTech Connect

    Kamath, Archana; S, Raghu; V, Mini; C, Sharanappa; H, Devendrappa

    2015-06-24

    The optical absorbance spectra of solution casted pure & methyl blue (MB) dyed polyethylene oxide (PEO) films were recorded in a wavelength range from 190-1100nm at different temperatures. The absorbance was found to increases with increasing temperature. Fluorescence micrographs confirmed the interaction between polymer and dye and also revealed decreased crystallinity of the sample. Fluorescence quantum yield has been calculated with the help of fluorescence spectra.

  1. {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.

  2. {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.

  3. 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

  4. Na(3)DyCl(6).

    PubMed

    Schurz, Christian M; Meyer, Gerd; Schleid, Thomas

    2011-05-01

    Single crystals of the title compound, tris-odium hexa-chloridodysprosate, Na(3)DyCl(6), 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 (Na(3)AlF(6)) and the high-temperature structure of the Na(3)MCl(6) series, with M = Eu-Lu, Y and Sc. The isolated, almost perfect [DyCl(6)](3-) octa-hedra are inter-connected via two crystallographically different Na(+) cations: while one Na(+) resides on centres of symmetry (as well as Dy(3+)) and also builds almost perfect, isolated [NaCl(6)](5-) octa-hedra, the other Na(+) is surrounded by seven chloride anions forming a distorted [NaCl(7)](6-) trigonal prism with just one cap as close secondary contact. PMID:21754259

  5. 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

  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. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. "Quasi-Antiferromagnetic" Ordering in the R-Mg-Zn Icosahedral Alloys? The Case of Tb-Mg-Zn

    NASA Astrophysics Data System (ADS)

    Goldman, A. I.; Islam, Z.; Fisher, I. R.; Panchula, A. F.; Cheon, K. O.; Canfield, P. C.; Stassis, C.; Zarestky, J.

    1998-03-01

    Recently, it was reported that long-range magnetic ordering was observed in several of the new rare earth containing icosahedral alloys, R-Mg-Zn (R=Tb, Dy, Ho, Er) (B. Charrier et al., Phys. Rev. Lett. 78, 4637, 1997.). At low temperatures, the antiferromagnetic Bragg peaks, while weak, could be indexed to the icosahedral parent phase with good accuracy. In addition, significant magnetic diffuse scattering, indicating only short-range magnetic order, was also observed. However, bulk magnetization measurements have evidenced only a spin-glass transition at low temperatures, and no antiferromagnetic transition. We will report on new neutron scattering measurements of the magnetic order in Tb-Mg-Zn powder samples produced from crushed single-crystals, used to improve sample purity. Our results for these samples show only the diffuse component of the magnetic scattering at low temperature, and no antiferromagnetic Bragg peaks. We will discuss several possibilities for the discrepencies between the two experiments.

  14. Elevated overview of Piers GD1 and GD2, showing rail lines, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Elevated overview of Piers GD-1 and GD-2, showing rail lines, GD-2 Quay Wall of Dry Dock No. 2 on left - U.S. Naval Base, Pearl Harbor, Dry Dock No. 1, Approach Pier & Caisson Docking Wharf, Ocean end of Fifth Street between Dry Dock Nos. 1 & 2, Pearl City, Honolulu County, HI

  15. Magnetic structure of dysprosium in epitaxial Dy films and in Dy/Er superlattices

    SciTech Connect

    Dumesnil, K.; Dufour, C.; Mangin, P.; Marchal, G.; Hennion, M.

    1996-09-01

    We present a magnetization and neutron-diffraction study of the basal plane magnetic structure of Dy epitaxial films and Dy/Er superlattices. The thermal evolution of the magnetic phases, the stability of the helical phase under a magnetic field, the thermal variation of the dysprosium in-plane and {ital c} parameters, and of the dysprosium turn angle are successively shown. In Dy/Er superlattices, the dysprosium helix propagates coherently through paramagnetic erbium; at low temperature, individual dysprosium layers undergo a ferromagnetic transition and are coupled antiferromagnetically to each other for erbium layers thicknesses larger than 20 A. In dysprosium films, as expected from the epitaxy effect, the Curie temperature of dysprosium is reduced if dysprosium is grown on yttrium and increased if it is grown on erbium, whereas it is unexpectedly close to the bulk value in Dy/Er superlattices. This amazing value of the Curie temperature in superlattices is correlated to two main experimentally observed effects: (i) the magnetoelastic driving force is reduced compared to bulk dysprosium because of the clamped {gamma} distortion; (ii) the difference between the exchange energies in the helical and the ferromagnetic phases is increased compared to the bulk value. {copyright} {ital 1996 The American Physical Society.}

  16. 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

  17. 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

  18. TB an epidemic in Russia's prisons.

    PubMed

    1999-01-01

    Over 100,000 prisoners are infected with tuberculosis (TB) in Russia, which has the highest incarceration rate in the world. Drug-resistant TB is found in thousands of inmates, and approximately 20,000 have died from it within the past 2 years. Although the country now has 50 centers for TB-infected prisoners, many are not being cured because of medicine shortages and failure to complete treatment. Up to 25 percent of TB infections found in Russian jails are multi-drug resistant, as opposed to 4 percent in Russia's general population and under 2 percent in the United States. PMID:11367347

  19. 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...

  20. Radiative strength functions in {sup 163,164}Dy

    SciTech Connect

    Nyhus, H. T.; Siem, S.; Guttormsen, M.; Larsen, A. C.; Buerger, A.; Syed, N. U. H.; Tveten, G. M.; Voinov, A.

    2010-02-15

    The nuclei {sup 163,164}Dy have been investigated using the Oslo method on data from the pickup reaction {sup 164}Dy({sup 3}He,{alpha}{gamma}){sup 163}Dy and the inelastic scattering {sup 164}Dy({sup 3}He,{sup 3}He{sup '}{gamma}){sup 164}Dy, respectively. The radiative strength functions for both nuclei have been extracted, and a small resonance centered around E{sub {gamma}}approx =3 MeV is observed in both cases. The parameters of this so-called pygmy M1 resonance (the scissors mode) are compared with previous results on {sup 160,161,162}Dy using the Oslo method, and with data on {sup 163}Dy measured by the Prague group using the two-step cascade method. In particular, the integrated reduced transition probability B(M1arrow up) of the pygmy resonance is compared with neighboring dysprosium isotopes. We also observe an enhanced strength in the region above E{sub {gamma}}approx =5 MeV in {sup 164}Dy. Possible origins of this feature are discussed.

  1. Radiative strength functions in Dy163,164

    NASA Astrophysics Data System (ADS)

    Nyhus, H. T.; Siem, S.; Guttormsen, M.; Larsen, A. C.; Bürger, A.; Syed, N. U. H.; Tveten, G. M.; Voinov, A.

    2010-02-01

    The nuclei Dy163,164 have been investigated using the Oslo method on data from the pickup reaction Dy164(He3,αγ)Dy163 and the inelastic scattering Dy164(He3,He3'γ)Dy164, respectively. The radiative strength functions for both nuclei have been extracted, and a small resonance centered around Eγ≈3 MeV is observed in both cases. The parameters of this so-called pygmy M1 resonance (the scissors mode) are compared with previous results on Dy160,161,162 using the Oslo method, and with data on Dy163 measured by the Prague group using the two-step cascade method. In particular, the integrated reduced transition probability B(M1↑) of the pygmy resonance is compared with neighboring dysprosium isotopes. We also observe an enhanced strength in the region above Eγ≈5 MeV in Dy164. Possible origins of this feature are discussed.

  2. Phases observed at 900-1100 degree C in the binary Ln-Ba-O systems for Ln = Dy, Ho, Er, Tm, and Yb

    SciTech Connect

    Hodorowicz, E.; Hodorowicz, S.A.; Eick, H.A. )

    1990-02-01

    The compounds Ln{sub 2}Ba{sub 2}O{sub 5}, Ln{sub 2}Ba{sub 4}O{sub 7}, and Ln{sub 4}Ba{sub 3}O{sub 9}, for Ln = Dy, Ho, Er, Tm, and Yb, have been prepared and characterized by X-ray powder diffraction. Phase interrelationships were established as a function of temperature by quenching specimens annealed at 900-l 100{degree}C. Comparable Ln = Tb phases could not be prepared. Lattice parameters are presented for all phases observed.

  3. 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.

  4. Magnetic properties of Dy3+ ions and crystal field characterization in YF3:Dy3+ and DyF3 single crystals

    NASA Astrophysics Data System (ADS)

    Savinkov, A. V.; Korableva, S. L.; Rodionov, A. A.; Kurkin, I. N.; Malkin, B. Z.; Tagirov, M. S.; Suzuki, H.; Matsumoto, K.; Abe, S.

    2008-12-01

    The dc magnetic susceptibilities of the orthorhombic DyF3 single crystals have been measured in the temperature range between 1.8 and 300 K. The susceptibility along the b-axis does not depend on temperature below TC = 2.55 K and is equal to the demagnetizing factor of the sample, that gives evidence for the ferromagnetic phase induced by the magnetic dipole-dipole interactions between the Dy3+ ions. The saturation moment of 8.5 μB/Dy3+ along the b-axis was determined from magnetization measurements. The observed strong anisotropy of the magnetic susceptibility at low temperatures agrees with the measured anisotropic g-tensor of the ground state of impurity Dy3+ ions in YF3 single crystals. The results of measurements are interpreted in the frameworks of the crystal field theory and the mean magnetic field approximation.

  5. 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.

  6. 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.

  7. TB in Correctional Facilities Is a Public Health Concern

    MedlinePlus

    ... component to TB elimination in the United States. Tuberculosis (TB) is a disease caused by bacteria that ... is essential to these efforts. More Information Reported Tuberculosis in the United States, 2012 TB in Correctional ...

  8. Photoluminescence properties of thermographic phosphors YAG:Dy and YAG:Dy, Er doped with boron and nitrogen

    NASA Astrophysics Data System (ADS)

    Chepyga, Liudmyla M.; Jovicic, Gordana; Vetter, Andreas; Osvet, Andres; Brabec, Christoph J.; Batentschuk, Miroslaw

    2016-08-01

    This paper investigates Dy3+-doped and Dy3+, Er3+-co-doped yttrium aluminum garnets (YAG) with the admixture of boron nitride with the aim of using them as efficient thermographic phosphors at high temperatures. The phosphors were synthesized using a conventional high-temperature solid-state method. The influence of two fluxes, B2O3 and LiF/NH4F, and the effect of activator and coactivator concentrations were investigated. Additionally, the effect of B3+ and N3- substituting for Al3+ and O2- ions, respectively, in the YAG:Dy3+ co-doped with Er3+ was studied for the first time. The changes in the host lattice led to a much stronger photoluminescence compared with the samples without B3+ and N3- substitution. The admixture of BN also improves the thermal sensitivity of the YAG:Dy and YAG:Dy, Er thermographic phosphors.

  9. 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

  10. 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...

  11. 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...

  12. 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...

  13. 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...

  14. 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

  15. 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.

  16. Search for superdeformed bands in {sup 154}Dy

    SciTech Connect

    Nisius, D.; Janssens, R.V.F.; Khoo, T.L.

    1995-08-01

    The island of superdeformation in the vicinity of the doubly magic {sup 152}Dy yrast superdeformed (SD) band is thought to be well understood in the framework of cranked mean field calculations. In particular, the calculations suggested that in {sup 154}Dy there should be no yrast or near yrast SD minimum in the 40-60 h spin range, where SD bands in this mass region are thought to be {sup 153}Dy nucleus, it is populated. However, with the presence of five SD bands in the neighboring necessary to ascertain if the addition of one single neutron diminishes the importance of shell effects to the extent that superdeformation can no longer be sustained. In an experiment utilizing the increased resolving power of the early implementation phase of Gammasphere, the reaction {sup 122}Sn({sup 36}S,4n) at 165 MeV was employed to populate high spin states in {sup 154}Dy. In a four-day run with 36 detectors, over one billion triple and higher fold coincidence events were recorded. One new SD band was identified and was assigned to {sup 154}Dy. From comparisons with the Im{sup (2)} moments of inertia of the SD bands in {sup 152}Dy and {sup 153}Dy, a configuration based on (514)9/2{sup 2} neutrons coupled to the {sup 152}Dy SD core was proposed. One unexpected and as yet unexplained feature of this new SD band is that the transition energies are almost identical to those of an excited SD band in {sup 153}Dy. It is also worth noting that the feeding of the yrast states is similar to that achieved by the deexcitation from the ensemble of all entry states in the reaction. This observation emphasizes the statistical nature of the decay-out process. A paper reporting these results was accepted for publication.

  17. The Precataclysmic Variable GD 245

    NASA Astrophysics Data System (ADS)

    Schmidt, Gary D.; Smith, Paul S.; Harvey, David A.; Grauer, Albert D.

    1995-07-01

    A combined photometric/spectroscopic study has been carried out of the evolved binary GD 245. The system is shown to consist of a DA2 white dwarf plus M3-5 secondary in a 4.17 h orbit. From model fitting to the white dwarf spectral features, the primary star is found to have log g=7.77±0.02 and Teff=22170 K, leading to M1 (g)=0.48 Msun and R1=0.015 Rsun. Radial velocity analysis of the double-lined system implies M2=0.22 Msun. The distance is computed to be 61 pc and the orbital inclination is i≍69°. These parameters are consistent with the companion being a main-sequence object, in which case Teff=3S60 K, R2=0.27 Rsun, and the binary just escapes being an eclipsing system. A rich spectrum of emission lines phased in strength and radial velocity with the orbital motion is testimony to irradiation of a corotating secondary star by the white dwarf. However, the strength of this spectral component exceeds the intercepted Lyman continuum from the white dwarf, implying that alternate heating mechanisms are important. The companion underfills its Roche lobe by less than 25% in radius, and for current estimates of the angular momentum loss rate in close binaries will require less than 108 yr to evolve into contact. At the inception of mass transfer, the cataclysmic variable GD 245 will appear as one of the rare objects in the 2-3 h orbital period gap.

  18. Acetato-bridged dinuclear lanthanide complexes with single molecule magnet behaviour for the Dy2 species.

    PubMed

    Zhang, Haixia; Lin, Shuang-Yan; Xue, Shufang; Wang, Chao; Tang, Jinkui

    2014-04-28

    Five dinuclear lanthanide complexes with formula [Ln2L2(OAc)4(MeOH)a(H2O)b] · cMeOH · dH2O (a = 2, b = 0, c = 2, d = 0, Ln = Sm (1), Gd (2), Dy (3); a = 0, b = 2, c = 4, d = 2, Ln = Tm (4)) and [Yb2L2(OAc)4(MeOH)2]·[Yb2L2(OAc)4(H2O)2] · 2H2O (5) (HL = (E)-N'-(2-hydroxybenzylidene)-2-mercaptonicotinohydrazide), have been synthesized and their crystal structures and magnetic properties are reported. All five complexes are centrosymmetric, showing a similar dinuclear core with two lanthanide ions in each complex being bridged by acetate groups in the η(1):η(2):μ2 mode. The various coordination modes of acetate groups result in two kinds of coordination geometries for Ln ions with the ones in complexes 1-4 and the Yb2 in 5 being nine-coordinated with a mono-capped square antiprism geometry, while the Yb1 ions in the other part of complex 5 are eight-coordinated with a triangular dodecahedron geometry. Magnetic susceptibility studies reveal that complex 3 shows single molecule magnet behaviour with an energy barrier of 39.1 K. In addition, comparison of the structural parameters among the similar Dy2 SMMs with a η(1):η(2):μ2 coordination mode of carboxylate groups reveals the significant role played by coordination geometry in modulating the relaxation dynamics of SMMs. PMID:24599563

  19. A new method of making 164Dy metal plate targets

    NASA Astrophysics Data System (ADS)

    Sugai, Isao; Kato, Hajime

    1986-04-01

    164Dy metal plate targets of high purity for measurements of the electron neutrino mass were made successfully. The starting material 164DyF 3 was reduced to metal by the Ca reduction method with rf induction heating. The reduced metal was pressed with a hot-press device in argon gas atmosphere and rolled into plates of 35 mm × 10 mm in area by a new method of packing. The thicknesses were in the range from 150 to 230 mg/cm 2. The present method was also found suitable to make thin Dy targets of the order of 1 mg/cm 2 in thickness

  20. 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.

  1. Two novel Dy8 and Dy11 clusters with cubane [Dy4(μ3-OH)4]8+ units exhibiting slow magnetic relaxation behaviour.

    PubMed

    Miao, Yan-Li; Liu, Jun-Liang; Li, Jin-Yan; Leng, Ji-Dong; Ou, Yong-Cong; Tong, Ming-Liang

    2011-10-21

    Two unique octa- and hendeca-nuclear dysprosium(III) clusters incorporating [Dy(4)(μ(3)-OH)(4)](8+) cubane units have been synthesized with the 1,10-phenanthroline-2,9-dicarbaldehyde dioxime (H(2)phendox) ligand and DyCl(3)·6H(2)O or Dy(OAc)(3)·4H(2)O. They are [Dy(8)(OH)(8)(phendox)(6)(H(2)O)(8)]Cl(2)(OH)(2)·18H(2)O·18MeOH (1) and [Dy(11)(OH)(11)(phendox)(6)(phenda)(3)(OAc)(3)](OH)·40H(2)O·7MeOH (2). Adjacent Dy(8) in 1 or Dy(11) in 2 motifs are packed by off-set π-π interactions of the aromatic rings on phendox(2-) to generate a 3D supramolecular architecture in the honeycomb topology and with 1D or 3D channels along the c-axis. Adsorption research shows that complex 1 has selective adsorption ability for H(2)O over small gas molecules (H(2), N(2), CO(2)). Complex 2 is stable upon the removal of guest molecules and the desolvated compound absorbed a considerable amount of CO(2). Furthermore, the oximes underwent hydrolysis to carboxylic acid and the resulting 1,10-phenanthroline-2,9-dicarboxylate link the dysprosium atoms to form a hendecanuclear cluster of 2. Magnetic studies reveal that both clusters exhibit slow magnetic relaxation behavior, expanding upon the recent reports of the pure 4f type single-molecule magnets (SMMs). PMID:21894344

  2. Probing the Structure-Relaxivity Relationship of Bishydrated Gd(DOTAla) Derivatives

    PubMed Central

    Boros, Eszter; Caravan., Peter

    2016-01-01

    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 presence of 100 fold excess phosphate, relaxivity was slightly increased and typical for q=2 complexes of this size (8.3 mM-1s -1 and 9.5 mM-1s -1 respectively at 37 °C, 60 MHz). Relaxivity for the complexes in presence of HSA corresponded well to relaxivity obtained for complexes with reduced access for inner-sphere water (13.5 and 12.7 mM-1s-1 at 37 °C, 60 MHz). Mean water residency time at 37 °C was determined using temperature dependent 17O-T2 measurements at 11.7T and calculated to be 310τM = 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)]. Over all, we found that 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

  3. Partners against tuberculosis: Ethiopia's "TB clubs".

    PubMed

    Getahun, H

    1998-11-01

    TB (tuberculosis) clubs were first introduced in the Estie district of South Gonder administrative zone, Amhara region of northwestern Ethiopia in January 1997, in an attempt to improve TB control in rural areas. Before the clubs were introduced, patients who were family members or close neighbors were given different treatment follow-up dates. Walking long distances alone to secure treatment, patients often grew discouraged from continuing treatment once their health began to improve. However, upon the introduction of the TB clubs, neighboring patients, or those in the same family, had their follow-up appointment dates rearranged in the same clinics. Local neighborhoods were also used to group nearby patients in the same follow-up clinic. The patients then formed their own groups (TB clubs) and elected leaders. 3-10 members usually comprise each club, with the club leaders monitoring drug intake and new developments, such as drug side effects and toxic skin reactions. The social ostracism and stigma otherwise experienced by patients have been largely overcome as a result of the TB information disseminated within the communities by the clubs, while patient attendance for treatment has increased from 68% to 98%, according to one study's findings. This intervention has taken place using the long-course treatment protocol (2STH/EH and 10TH/EH). TB clubs are improving patient adherence to treatment, passive case detection, defaulter tracing, TB reporting and recording, and community involvement in health care. PMID:12294916

  4. 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.

  5. A trimetallic strategy towards ZnDyCr and ZnDyCo single-ion magnets.

    PubMed

    Hu, Kong-Qiu; Jiang, Xiang; Wu, Shu-Qi; Liu, Cai-Ming; Cui, Ai-Li; Kou, Hui-Zhong

    2015-09-21

    Two cyano- and phenoxo-bridged octanuclear complexes ZnDyCo (complex ) and ZnDyCr (complex ) with diamagnetic Zn(ii) and Co(iii) are reported. Dy(iii) is surrounded by nine oxygen atoms of two [Zn(Me2valpn)] (Me2valpn(2-) = dianion of N,N'-2,2-dimethylpropylenebis(3-methoxysalicylideneimine)) and one water molecule. Magnetic studies reveal that both exhibit single-ion magnet (SIM) behavior with the energy barrier of 85.9 K for complex and 100.9 K for complex . PMID:26256244

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Lanthanide-doped NaGdF4 core-shell nanoparticles for non-contact self-referencing temperature sensors

    NASA Astrophysics Data System (ADS)

    Zheng, Shuhong; Chen, Weibo; Tan, Dezhi; Zhou, Jiajia; Guo, Qiangbing; Jiang, Wei; Xu, Cheng; Liu, Xiaofeng; Qiu, Jianrong

    2014-05-01

    We report that non-contact self-referencing temperature sensors can be realized with the use of core-shell nanostructures. These lanthanide-based nanothermometers (NaGdF4:Yb3+/Tm3+@Tb3+/Eu3+) exhibit higher sensitivity in a wide range from 125 to 300 K based on two emissions of Tb3+ at 545 nm and Eu3+ at 615 nm under near-infrared laser excitation.We report that non-contact self-referencing temperature sensors can be realized with the use of core-shell nanostructures. These lanthanide-based nanothermometers (NaGdF4:Yb3+/Tm3+@Tb3+/Eu3+) exhibit higher sensitivity in a wide range from 125 to 300 K based on two emissions of Tb3+ at 545 nm and Eu3+ at 615 nm under near-infrared laser excitation. Electronic supplementary information (ESI) available: Experimental details and supplementary data. See DOI: 10.1039/c4nr00432a

  11. 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

  12. 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...

  13. HIV-Associated TB: Facts 2013

    MedlinePlus

    ... Intensified case finding for TB, Isoniazid preventive therapy (IPT), and Infection control) will reduce the burden of ... the 42 countries that reported data for 2012, IPT was provided to 520,000 people living with ...

  14. 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 ...

  15. Magnetic Transport Properties in GdBa2Cu3- x Ru x O7- δ Superconducting Phase

    NASA Astrophysics Data System (ADS)

    Abou-Aly, A. I.; Mahmoud, S. A.; Awad, R.; Ibrahim, I. H.; Barakat, M. Me.

    2012-04-01

    Bulk superconducting samples of type GdBa2Cu3- x Ru x O7- δ phase, Gd-123, with x ranging from 0.0 to 0.15 were prepared by the conventional solid-state reaction technique. X-ray powder diffraction (XRD) and the electrical resistivity measurements were performed in order to investigate the effect of Ru4+ ions substitution on Gd-123 phase. Enhancement of the phase formation and the superconducting transition temperature T c for GdBa2Cu3- x Ru x O7- δ phase up to x=0.05 was observed. The effect of magnetic field up to 4.4 kG on the electrical resistivity behavior of the prepared samples was studied to investigate the flux motion of this phase. The derived flux pinning energy U, based on the thermally activated flux creep TAFC model, decreased with increasing the magnetic field B. The flux pinning energy followed the exponent behavior as U( B)˜ B - β . The superconducting transition width ΔT increased as the magnetic field increased, showing the scaling relation as ΔT˜ B n . Using Ambegaokar and Halperin AH theory, the magnetic field and temperature dependence of U was found to be U( B, T)˜ ΔTB - η , η= β+ n. The critical current density J c (0) enhanced up to x=0.05, beyond which it decreased with further increase in Ru-content.

  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. 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

  18. Oblique view of GD5 taken from Pier GD4 U.S. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Oblique view of GD-5 taken from Pier GD-4 - U.S. Naval Base, Pearl Harbor, Pier & Quay Walls, Entrance to Dry Dock No. 2 & Repair Wharfs, east & west sides of Dry Dock No. 2 & west side of Dry Dock No. 3, Pearl City, Honolulu County, HI

  19. GD4 with GD3 at oblique view on left U.S. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    GD-4 with GD-3 at oblique view on left - U.S. Naval Base, Pearl Harbor, Pier & Quay Walls, Entrance to Dry Dock No. 2 & Repair Wharfs, east & west sides of Dry Dock No. 2 & west side of Dry Dock No. 3, Pearl City, Honolulu County, HI

  20. Pier GD3, oblique view taken from Pier GD2, Caisson of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Pier GD-3, oblique view taken from Pier GD-2, Caisson of Dry Dock No. 2 to left - U.S. Naval Base, Pearl Harbor, Pier & Quay Walls, Entrance to Dry Dock No. 2 & Repair Wharfs, east & west sides of Dry Dock No. 2 & west side of Dry Dock No. 3, Pearl City, Honolulu County, HI

  1. Overview of GD2 and GD3 with Caisson of Dry Dock ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Overview of GD-2 and GD-3 with Caisson of Dry Dock No. 2 in center - U.S. Naval Base, Pearl Harbor, Pier & Quay Walls, Entrance to Dry Dock No. 2 & Repair Wharfs, east & west sides of Dry Dock No. 2 & west side of Dry Dock No. 3, Pearl City, Honolulu County, HI

  2. Oblique of GD4 and GD5, Dry Dock No. 3 Caisson ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Oblique of GD-4 and GD-5, Dry Dock No. 3 Caisson between piers - U.S. Naval Base, Pearl Harbor, Pier & Quay Walls, Entrance to Dry Dock No. 2 & Repair Wharfs, east & west sides of Dry Dock No. 2 & west side of Dry Dock No. 3, Pearl City, Honolulu County, HI

  3. GD2 and GD3 synthase: novel drug targets for cancer therapy

    PubMed Central

    Sphyris, Nathalie; Sarkar, Tapasree Roy; Battula, Venkata L; Andreeff, Michael; Mani, Sendurai A

    2015-01-01

    Our recent study suggests that targeting GD3 synthase (also known as ST8SIA1)—the rate-limiting enzyme in biosynthesis of the breast cancer stem cell marker GD2—abrogates metastasis and depletes the cancer stem cell populations within a tumor, thus providing an effective therapeutic strategy against metastatic breast cancers. PMID:27308452

  4. Neutron diffraction studies of RSn{sub 1+x}Ge{sub 1-x} (R=Tb-Er) compounds

    SciTech Connect

    Gil, A.; Hoser, A.; Szytula, A.

    2011-07-15

    The magnetic structures of RSn{sub 1+x}Ge{sub 1-x} (R=Tb, Dy, Ho and Er, x{approx}0.1) compounds have been determined by neutron diffraction studies on polycrystalline samples. The data recorded in a paramagnetic state confirmed the orthorhombic crystal structure described by the space group Cmcm. These compounds are antiferromagnets at low temperatures. The magnetic ordering in TbSn{sub 1.12}Ge{sub 0.88} is sine-modulated described by the propagation vector k=(0.4257(2), 0, 0.5880(3)). Tb magnetic moment equals 9.0(1) {mu}{sub B} at 1.62 K. It lies in the b-c plane and form an angle {theta}=17.4(2) deg. with the c-axis. This structure is stable up to the Neel temperature equal to 31 K. The magnetic structures of RSn{sub 1+x}Ge{sub 1-x}, where R are Dy, Ho and Er at low temperatures are described by the propagation vector k=(1/2, 1/2, 0) with the sequence (++-+) of magnetic moments in the crystal unit cell. In DySn{sub 1.09}Ge{sub 0.91} and HoSn{sub 1.1}Ge{sub 0.9} magnetic moments equal 7.25(15) and 8.60(6) {mu}{sub B} at 1.55 K, respectively. The moments are parallel to the c-axis. For Ho-compound this ordering is stable up to T{sub N}=10.7 K. For ErSn{sub 1.08}Ge{sub 0.92}, the Er magnetic moment equals 7.76(7) {mu}{sub B} at T=1.5 K and it is parallel to the b-axis. At T{sub t}=3.5 K it tunes into the modulated structure described by the k=(0.496(1), 0.446(4), 0). With the increase of temperature there is a slow decrease of k{sub x} component and a quick decrease of k{sub y} component. The Er magnetic moment is parallel to the b-axis up to 3.9 K while at 4 K and above it lies in the b-c plane and form an angle 48(3) deg. with the c-axis. In compounds with R=Tb, Ho and Er the magnetostriction effect at the Neel temperature is observed. - Graphical abstract: The magnetic structures of RSn{sub 1+x}Ge{sub 1-x} (R=Tb, Dy, Ho and Er, x{approx}0.1) compounds have been determined by neutron diffraction studies on polycrystalline samples. The magnetic ordering in Tb

  5. Transfer of Excitation Energy from Pr3+ to Gd3+ in YF3:Pr3+,Gd3+

    NASA Astrophysics Data System (ADS)

    Hirai, Takeshi; Yoshida, Hisashi; Sakuragi, Shiro; Hashimoto, Satoshi; Ohno, Nobuhito

    2007-02-01

    Luminescence and excitation spectra for YF3:Gd3+, YF3:Pr3+, and YF3:Pr3+,Gd3+ have been studied in the vacuum ultraviolet (VUV) spectral region at room temperature. In YF3:Gd3+, Gd3+ ions absorb VUV light ranging from 150 to 200 nm due to 4 f-4 f transitions, yielding an ultraviolet (UV) luminescence line at 311 nm originating from the 4 f-4 f transition (6P7/2→8S7/2 state). In YF3:Pr3+,Gd3+, Pr3+ ions absorb the VUV light (150-200 nm) due to 4 f-5d transitions, and the absorption gives rise to the UV luminescence of Gd3+ ions that is much stronger than that of YF3:Gd3+. In this paper, we discuss the energy transfer process from Pr3+ to Gd3+ ions in YF3:Pr3+,Gd3+ excited by VUV light.

  6. 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.

  7. Lifetime Measurements of Levels in 160Gd

    NASA Astrophysics Data System (ADS)

    Casarella, Clark; Aprahamian, Ani; Crider, Ben; Lesher, Shelly; Marsh, Ian; Peters, Erin; Prados-Estevez, Francisco; Smith, Mallory; Vanhoy, Jeffrey; Yates, Steven

    2013-10-01

    The rare earth region of nuclei has been well established as a region of deformation for decades. However, the nature of vibrations built on a deformed ground state remain far from understood and present an oustanding challenge to nuclear structure physics. Studies of 158Gd has shown a preponderance of excited 0+ states with varying degrees of collectivity. We have measured level lifetimes, reduced transition probabilities and angular distributions of gamma-rays excited by inelastic neutron scattering and the use of the Doppler Shift Attenuation Method (DSAM) at the University of Kentucky 7 MV Van de Graaff Accelerator Facility. Low lying excited states of 160Gd were populated up to an excitation energy of E < 2 MeV. We will present and discuss the measured level lifetimes of 160Gd and their implied degrees of collectivity. This work was supported by the NSF under contract numbers PHY-1068192, PHY-12-05412, and PHY-0956310.

  8. Pulsating White Dwarf Star GD99

    NASA Astrophysics Data System (ADS)

    Chynoweth, K. M.; Thompson, S.; Mullally, F.; Yeates, C.

    2004-12-01

    We present 15 hours of time-series photometry of the variable white dwarf star GD99. These data were obtained at the McDonald Observatory 2.1m Otto Struve Telescope in January 2003, using the Argos CCD photometer. We achieved a noise level as low as 0.07 %, as measured from the power spectrum of our first night. Our observations confirm that GD99 is a unique pulsating white dwarf whose modes show characteristics of both the hot and cold type of DA variable stars. Additionally, GD99 has a large number of modes, making it a good candidate for asteroseismological study. Our preliminary results indicate that this star merits further study to decipher its abundant set of unusual modes. With such a rich period structure, longer continuous data sets will be required to fully resolve the pulsation spectrum.

  9. 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

  10. 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.

  11. 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)...

  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. 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)...

  14. 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)...

  15. 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

  16. Two distinct Dy-isophthalates induced by different solvents

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Huang, Yuan-Yuan; Yao, Yuan-Gen

    2012-09-01

    Two distinct Dy-isophthalates, [Dy4(m-BDC)6(H2O)4(DMF)]nṡ2n(H2O)ṡn(DMF) 1 and [Dy2(m-BDC)3(H2O)(DMA)]nṡ3n(H2O)ṡ2n(DMA) 2 (DMF = N,N'-Dimethylformamide, DMA = N,N'-Dimethylacetamide), which were induced by different solvents under the same hydrothermal conditions, were obtained. Single-crystal analysis revealed that compounds 1 and 2 feature two-dimensional (2D) layer structure with opened widows occupied by guests (DMF for 1 and DMA for 2). In addition, a rare hybrid [(H2O)3(DMA)2] pentamer was found in 2. Furthermore, thermal analyses of 1-2 were also investigated.

  17. Broad Feshbach resonances in collisions of Dy atoms

    NASA Astrophysics Data System (ADS)

    Julienne, P.; Jachymski, K.; Maier, T.; Ferrier-Barbut, I.; Karan, H.; Schmitt, M.; Wenzel, M.; Wink, C.; Pfau, T.

    2016-05-01

    RF spectroscopy of weakly bound dimers of ultra cold bosonic Dy atoms gives evidence for the emergence of a universal s-wave halo state in a background of chaotic background resonance states. The halo state is associated with a broad magnetic Feshbach resonance. Using a coupled channels theory taking into account the short ranged van dear Waals interaction and a correction due to the strong dipole moment of Dy, we are able to extract the scattering length as a function of magnetic field tuning near two such broad resonances. These results offer prospects for tuning the interactions of Dy atoms in a regime where three-body losses are not too strong. Supported in part by the DFG, the Foundation for Polish Science International Ph. D Projects Programme, and an AFOSR MURI.

  18. Magnetic structure of TbNi{sub 2}B{sub 2}C

    SciTech Connect

    Dervenagas, P.; Zarestky, J.; Stassis, C.; Goldman, A.I.; Canfield, P.C.; Cho, B.K.

    1996-04-01

    Neutron-diffraction techniques have been used to study the magnetic structure of TbNi{sub 2}B{sub 2}C. The measurements, performed on single crystals of this compound, show that below approximately 15 K the moments order in an almost longitudinal spin wave with wave vector along {ital a}{sup {asterisk}}. The magnitude of the wave vector is close to that obtained in the Ho, Er, and Gd compounds. This observation provides additional evidence that there are common Fermi-surface nesting features along {ital a}{sup {asterisk}} in the rare-earth nickel boride carbides which cause the magnetic ordering of the rare-earth moments via the Ruderman-Kittel-Kasuya-Yosida mechanism. Below approximately 8 K, the experimental results indicate the development of a small ferromagnetic component. {copyright} {ital 1996 The American Physical Society.}

  19. 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

  20. Magnetic Order in TbCo2Zn20 and TbFe2Zn20

    SciTech Connect

    Tian, W.; Christianson, Andrew D; Zarestky, J. L.; Jia, S.; Bud'ko, S. L.; Canfield, P. C.; Piccoli, P. M. B.; Schultz, A. J.

    2010-01-01

    We report neutron di raction studies of TbCo2Zn20 and TbFe2Zn20, two isostructural compounds which exhibit dramatically di erent magnetic behavior. In the case of TbCo2Zn20, magnetic Bragg peaks corresponding to antiferromagnetic order are observed below TN 2.5 K with a propagation vector of (0.5 0.5 0.5). On the other hand, TbFe2Zn20 undergoes a ferromagnetic transition at temperatures as high as 66 K which shows a high sensitivity to sample-to-sample variations. Two samples of TbFe2Zn20 with the same nominal compositions but with substantially di erent mag- netic ordering temperatures (Tc 51 and 66 K) were measured by single crystal neutron di raction. Structural re nements of the neutron di raction data nd no direct signature of atomic site disorder between the two TbFe2Zn20 samples except for subtle di erences in the anisotropic thermal param- eters. The di erences in the anisotropic thermal parameters between the two samples is likely due to very small amounts of disorder. This provides further evidence for the extreme sensitivity of the magnetic properties of TbFe2Zn20 to small sample variations, even small amounts of disorder.

  1. 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.

  2. 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

  3. 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.

  4. Lifetimes and electromagnetic transition strength in 157Dy

    NASA Astrophysics Data System (ADS)

    Gladnishki, K. A.; Petkov, P.; Dewald, A.; Jolie, J.; Möller, O.; Saha, B.; Fitzler, A.; Jessen, K.; Tonev, D.; Klug, T.; Heinze, S.; von Brentano, P.; Rainovski, G.; Trichkova, M.; Bazzacco, D.; Ur, C. A.; Farnea, E.; Axiotis, M.; Lunardi, S.; de Angelis, G.; Napoli, D. R.; Marginean, N.; Martinez, T.; Caprio, M. A.

    2016-06-01

    Excited states in 157Dy have been studied by γ-γ coincidence measurements via the reaction 124Sn(36S,3n) at a beam energy of 155MeV. Lifetimes of the relatively lower-spin states in 157Dy were measured by means of the Recoil Distance Dopplershift technique in the coincidence mode. The experiment was performed at the Laboratori Nazionali di Legnaro with the GASP array and the Cologne plunger device. With the same setup a Doppler- shift attenuation (DSA) lifetime measurement was performed for the higher spin states. The Differential decay-curve method was applied for the lifetime determination.

  5. 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

  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. Tuberculosis: Learn the Signs and Symptoms of TB Disease

    MedlinePlus

    ... What's this? Submit Button Past Emails CDC Features Tuberculosis (TB) Disease: Symptoms & Risk Factors Language: English Español (Spanish) Recommend on Facebook Tweet Share Compartir Tuberculosis (TB) is a disease caused by bacteria that ...

  8. 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 ...

  9. Tuberculosis: The Connection between TB and HIV (the AIDS Virus)

    MedlinePlus

    ... Task Force Tuberculosis: The Connection between TB and HIV Recommend on Facebook Tweet Share Compartir Order this ... if I am infected with both TB and HIV? If you have HIV, it is important to ...

  10. HIV-1 and the immune response to TB

    PubMed Central

    Walker, Naomi F; Meintjes, Graeme; Wilkinson, Robert J

    2013-01-01

    TB causes 1.4 million deaths annually. HIV-1 infection is the strongest risk factor for TB. The characteristic immunological effect of HIV is on CD4 cell count. However, the risk of TB is elevated in HIV-1 infected individuals even in the first few years after HIV acquisition and also after CD4 cell counts are restored with antiretroviral therapy. In this review, we examine features of the immune response to TB and how this is affected by HIV-1 infection and vice versa. We discuss how the immunology of HIV–TB coinfection impacts on the clinical presentation and diagnosis of TB, and how antiretroviral therapy affects the immune response to TB, including the development of TB immune reconstitution inflammatory syndrome. We highlight important areas of uncertainty and future research needs. PMID:23653664

  11. 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.

  12. Sternohyoid muscle fatigue properties of dy/dy dystrophic mice, an animal model of merosin-deficient congenital muscular dystrophy.

    PubMed

    van Lunteren, Erik; Moyer, Michelle

    2003-10-01

    Humans with merosin-deficient congenital muscular dystrophy have both sucking problems during infancy and sleep-disordered breathing during childhood. We hypothesized that merosin-deficient pharyngeal muscles fatigue faster than normal muscles. This was tested in vitro using sternohyoid muscle from an animal model of this disease, the dy/dy dystrophic mouse. Isometric twitch contraction and half-relaxation times were similar for dy/dy and normal sternohyoid. However, rate of force loss during repetitive 25-Hz train stimulation was markedly diminished in dystrophic compared with normal sternohyoid muscle. Furthermore, force potentiation, which occurred during the early portion of the fatigue-inducing stimulation, had a longer duration in dystrophic compared with normal muscle (approximately 60 versus 20 s). As a result of these two processes, at the end of 2 min of stimulation, force of dystrophic muscle had decreased by 8 +/- 5% and that of normal muscle by 69 +/- 4% (p < 0.0001). The potassium-channel blocker, 3,4-diaminopyridine, increased force of dy/dy sternohyoid muscle during twitch and 25-Hz contractions by 148 +/- 20% (p < 0.00001) and 109 +/- 18% (p < 0.00002), respectively. During repetitive 25-Hz stimulation, force of 3,4-diaminopyridine-treated dystrophic muscle remained significantly higher than that of untreated muscle, despite the early force potentiation being eliminated and fatigue being accelerated. Thus, merosin deficiency reduces fatigue and prolongs the duration of force potentiation. The latter alterations may partially preserve the integrity of upper airway muscle function, without which the severity of pharyngeal complications (feeding problems, sleep-related respiratory dysfunction) might be even more pronounced in the human merosin-deficient congenital muscular dystrophies. PMID:12840158

  13. Electrochemical phase analysis of powders in the GdB4-GdB system

    SciTech Connect

    Tkach, A.V.; Masyuk, T.V.; Paderno, Y.B.

    1985-05-01

    In recent years solid-phase voltammetric analysis with a carbon paste electrode has been employed successfully for the determination of the phase composition of a number of oxide and sulfide materials. This is a rapid and highly sensitive method of quantitative analysis, offering many possibilities. In this paper the authors study the feasibility of using voltammetric analysis with a carbon paste electrode for investigating the phase composition of powders in the GdB4-GdB6 system.

  14. 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.; 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 γ-irradiation over a wide range of exposures (1–5 kGy). TL glow peak intensity increases with γ 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 γ-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 γ-rays.

  15. 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

  16. Boeing TB-29 Superfortress (B-29)

    NASA Technical Reports Server (NTRS)

    1945-01-01

    Boeing TB-29 Superfortress (B-29): Arriving for use with the NACA right at the end of World War II, this Boeing B-29 Superfortress was used for research into hydraulically boosting flight controls. After just over five years of study at Langley, the B-29 was returned to the Air Force.

  17. Effect of B³⁺-N³⁻ on YAG:Dy thermographic phosphor luminescence.

    PubMed

    Kwong, Wing Yin; Steinberg, Adam; Chin, Ya Huei

    2014-11-01

    The use of thermographic phosphors for high-temperature (>1000  K) thermometry currently is limited by loss of signal due to thermal quenching. This work demonstrates a new phosphor generated by substituting tetrahedral site Al(3+)-O(2-) in YAG:Dy with B(3+)-N(3-) to produce YABNG:Dy. Conventional YAG:Dy and YABNG:Dy phosphors were synthesized using identical solgel synthesis techniques. X-ray diffraction measurements showed that both had nearly pure crystalline phases, with a minor secondary yttrium-aluminum-monoclinic (YAM) phase present in the YABNG:Dy. The YABNG:Dy sample had a larger and more spherical primary grain than did the YAG:Dy in scanning electron microscopy images. Tests of the thermal response showed that the YABNG:Dy had much stronger phosphorescence emissions than did YAG:Dy, likely due to the morphological differences. Furthermore, the onset of thermal quenching was delayed by approximately 100 K for YABGN:Dy compared to YAG:Dy, and the rate of signal decrease with temperature was reduced. This resulted in greater signal-to-noise ratios and less uncertainty in the temperature measurements, particularly at high temperatures. PMID:25361305

  18. Decomposition of DyF3 and its effect on magnetic performance of DyF3-doped Nd-Fe-B-type hot-deformed magnet

    NASA Astrophysics Data System (ADS)

    Kim, J. Y.; Kwon, H. W.; Lee, J. G.; Yu, J. H.

    2015-05-01

    Decomposition of DyF3 and its effect on the magnetic performance of the hot-pressed compact and die-upset magnet of melt-spun Nd-Fe-B-type material were investigated. DyF3 was thermally decomposed above 660 °C, and this decomposition was linked closely to the coercivity enhancement. When the DyF3 doped flakes were hot-pressed above the decomposition temperature of DyF3, the diffusion of Dy into the flakes was promoted, and leading to profound coercivity enhancement. Coercivity of the hot-pressed magnet was further enhanced by post-hot-press annealing, and coercivity as high as 24.5 kOe was obtained after the optimum annealing. The DyF3 doped hot-deformed magnet exhibited enhanced magnetic performance (iHc = 17.5 kOe, Br = 12.8 kG, (BH)max = 37.6 MGOe) with respect to the un-doped magnet without sacrificing significant remanence. Coercivity was improved by 30%. In magnet in which the decomposition of DyF3 and Dy diffusion were fully accomplished, the region originally occupied by added DyF3 was completely replaced by NdF3.

  19. Tailoring the magnetism of Tb5Si2Ge2 compounds by La substitution

    SciTech Connect

    Belo, Joao; Pereira, Andre; Araujo, Joao Pedro; Dela Cruz, Clarina R; Moreira Dos Santos, Antonio F; Goncalves, Joao Nuno; Amaral, Vitor; Morellon, Luis; Ibarra, M. Ricardo; Algarabel, Pedro A.; Magen, C

    2012-01-01

    In order to study the crystal structure, phase relationships, and magnetic properties of the system Tb5-xLaxSi2Ge2, a series of polycrystalline samples with compositions ranging from x = 0 to x = 5 have been synthesized and characterized in detail. At room temperature, two structures have been detected: Compounds in the concentration range 0 <= x < 1 present a monoclinic Gd5Si2Ge2-type structure, while for x > 1 a tetragonal Zr5Si4-type structure is observed. The unit cell volume increases linearly with La concentration but with two different slopes: similar to 18 angstrom(3)/x and similar to 33 angstrom(3)/x for 0 <= x < 1 (monoclinic) andx > 1 (tetragonal), respectively. In the monoclinic region, an increase of T-C was observed, reaching a maximum value of T-C similar to 154 K, at the x = 0.75 composition. This feature is explained based on specific La occupancy at the R2 site which was supported by density functional calculations for low La concentration. The samples that crystallized in the tetragonal structure exhibit a linear decrease of T-C(x) with a slope of partial derivative T-C/partial derivative x similar to -38 K/x, reaching 0 K for the x = 5 composition. A magnetic and structural x-T phase diagram of the Tb5-xLaxSi2Ge2 system in the temperature range 4-300 K is proposed.

  20. 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