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1

Enhanced electrical resistivity before Nel order in the metals RCuAs2 (R=Sm, Gd, Tb, and Dy).  

PubMed

We report an unusual temperature (T) dependent electrical resistivity (rho) behavior in a class of ternary intermetallic compounds of the type RCuAs2 (R=rare earths). For some rare earths (Sm, Gd, Tb, and Dy) with negligible 4f hybridization, there is a pronounced minimum in rho(T) far above respective Nel temperatures (T(N)). However, for the rare earths which are more prone to exhibit such a rho(T) minimum due to 4f-covalent mixing and the Kondo effect, this minimum is depressed. These findings, difficult to explain within the hitherto-known concepts, present an interesting scenario in magnetism. PMID:12906433

Sampathkumaran, E V; Sengupta, Kausik; Rayaprol, S; Iyer, Kartik K; Doert, Th; Jemetio, J P F

2003-07-18

2

Study of electric quadrupole interactions at 111Cd on Zn sites in RZn (R = Ce, Gd, Tb, Dy) compounds using the PAC spectroscopy  

NASA Astrophysics Data System (ADS)

Nuclear quadrupole interactions at Zn sites in the intermetallic compounds RZn (R = Ce, Gd, Tb, Dy) have been investigated by perturbed gamma-gamma angular correlation (PAC) spectroscopy using 111In(111Cd) as probe nuclei. Measurements were carried out in the temperature range of 10-295 K. These compounds exhibit CsCl type cubic structure and while CeZn shows antiferromagnetic behaviour, the compounds GdZn, TbZn, DyZn are ferromagnetic. The results show that the EFG in these compounds is sensitive to the distribution of rare-earth 4f-electron charges.

Bosch-Santos, Brianna; Carbonari, Artur W.; Cabrera-Pasca, Gabriel A.; Costa, Messias S.; Saxena, Rajendra N.

2013-05-01

3

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

SciTech Connect

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

Velchuri, Radha; Kumar, B. Vijaya; Devi, V. Rama [Department of Chemistry, Osmania University, Hyderabad 500007 (India)] [Department of Chemistry, Osmania University, Hyderabad 500007 (India); Prasad, G. [Department of Physics, Osmania University, Hyderabad 500007 (India)] [Department of Physics, Osmania University, Hyderabad 500007 (India); Prakash, D. Jaya [College of Technology, Osmania University, Hyderabad 500007 (India)] [College of Technology, Osmania University, Hyderabad 500007 (India); Vithal, M., E-mail: muga_vithal@rediffmail.com [Department of Chemistry, Osmania University, Hyderabad 500007 (India)

2011-08-15

4

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

5

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

PubMed

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 (?, ?, and ?) were observed. A4O4Se3 materials adopt either the ? (A = Nd, Sm), ? (A = Eu), ? (A = Gd, Tb) or ? (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 Nel temperature, TN, of 7-9 K. DFT calculations confirm the two different valence states of Se(2-) and Se2(2-) in Eu4O4Se3. PMID:25581725

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

2015-02-01

6

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

PubMed

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

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

2014-09-15

7

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

PubMed

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

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

2013-10-21

8

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

PubMed

Reactions of Ln(III) perchlorate (Ln = Gd, Tb, Dy, and Ho), NiCl26H2O, and a polydentate Schiff base resulted in the assembly of novel isostructural hexanuclear Ni4Ln2 complexes [Ln = Gd (1), Tb (2), Dy (3), Ho (4)] with an unprecedented 3d-4f metal topology consisting of two defect-dicubane units. The corresponding Ni4Y2 (5) complex containing diamagnetic Y(III) atoms was also isolated to assist the magnetic studies. Interestingly, complexes 2 and 3 exhibit SMM characteristics and 4 shows slow relaxation of the magnetization. The absence of frequency-dependent in-phase and out-of-phase signals for the Ni-Y species suggests that the Ln ions' contribution to the slow relaxation must be effectual as previously observed in other Ni-Dy samples. However, the observation of ?? signals with zero dc field for the Ni-Tb and Ni-Ho derivatives is notable. Indeed, this is the first time that such a behavior is observed in the Ni-Tb and Ni-Ho complexes. PMID:24661008

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

2014-04-01

9

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

SciTech Connect

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

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

2008-04-15

10

Ferromagnetism in novel compounds of the R3Pt23Si11 series with heavy rare earth: Gd, Tb, Dy, Ho and Er  

NASA Astrophysics Data System (ADS)

We have synthesized new compounds of the R3Pt23Si11 series with R=Gd, Tb, Dy, Ho and Er, and studied their magnetic and thermodynamic properties. X-ray powder diffraction characterization confirms that all these compounds crystallize in the same face-centered cubic structure, space group Fm3m, as Ce3Pt23Si11. They all present a ferromagnetic order at low temperatures. The Curie temperatures range between 421 K and 3.390.05 K for Gd3Pt23Si11 and Er3Pt23Si11 respectively. For all compounds the value of the spontaneous moment at 2 K is far below the value expected for the saturated moment of the R3+ ions, except for the Gd compound. The estimations of the magnetic entropy at TC remain smaller than the full entropy of the fundamental multiplet, Rln(2J+1). Both reductions, of the moment and of the magnetic entropy, are ascribed to the crystal field effects. In the paramagnetic phase the thermal variation of the suceptibilities follows a Curie-Weiss law with Curie constants in good agreement with the theoretical values.

Opagiste, C.; Galra, R. M.

2014-05-01

11

Magnetic hyperfine field in antiferromagnetic RGa2 (R = Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er) studied by perturbed angular correlation spectroscopy using 111Cd  

NASA Astrophysics Data System (ADS)

The magnetic and electric hyperfine interactions of the nuclear probe Cd111 in the hexagonal antiferromagnetic rare earth-gallium RGa2 (R = Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er) intermetallic compounds have been investigated by perturbed angular correlation (PAC) spectroscopy as a function of temperature. With the exception of R = Nd and Ho, the magnetic hyperfine field Bhf is roughly proportional to the spin projection (g - 1)J of the R constituent. However, in the group of the light rare earths, the variation of Bhf with (g - 1)J is much weaker than that for the heavy R constituents, in contrast to the trend reported for all rare earth intermetallics investigated up to now as well as to the trend of the magnetic ordering temperatures of RGa2. The orientation of the 4f spins relative to the c axis of RGa2 deduced from the angle between Bhf and the symmetry axis of the electric field gradient was found to be temperature independent and in agreement with the results of previous magnetization measurements. Except for SmGa2 where the hyperfine field shows an abrupt decrease near TN, the temperature dependence of Bhf(T) is consistent with second order phase transitions. The magnetic ordering temperatures deduced from Bhf(T) agree with magnetization and neutron diffraction results.

Cavalcante, F. H. M.; Pereira, L. F. D.; Cavalcante, J. T.; Saitovitch, H.; Carbonari, A. W.; Saxena, R. N.; Forker, M.

2013-05-01

12

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

PubMed

The reaction between Ln(III) chloride and NiCl24H2O 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

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

2013-11-18

13

Structure and physical properties of ternary rare-earth cobalt bismuth intermetallics (RE)12Co5Bi (RE = Y, Gd, Tb, Dy, Ho, Er, Tm).  

PubMed

The rare-earth intermetallic compounds (RE)12Co5Bi (RE = Y, Gd, Tb, Dy, Ho, Er, Tm) were prepared by arc-melting and annealing at 600 degrees C. These compounds extend the previously known (RE)6M2+xX1-x (M = Co, Ni; X = Ga, In, Sn, Pb) series with the Ho6Co2Ga-type structure to X = Bi. The crystal structure of Ho12Co5Bi was refined by the Rietveld method from powder X-ray diffraction data obtained using synchrotron radiation (Pearson symbol oI36, orthorhombic, space group Immm, Z = 2, a = 9.37598(14) A, b = 9.37871(14) A, c = 9.85465(13) A). Unlike other Ho6Co2Ga-type compounds, the 2a site in Ho12Co5Bi is exclusively occupied by Co atoms. Four-probe electrical resistivity measurements on sintered polycrystalline samples of (RE)12Co5Bi indicated metallic behavior. Magnetic measurements revealed behavior ranging from frequency-dependent maxima in the ac susceptibility for Y12Co5Bi to possible ferrimagnetic ordering for Gd12Co5Bi to antiferromagnetic ordering with metamagnetic transitions for the remaining compounds. As confirmed by band structure calculations using Y12Co5Bi as a model compound, Y-Y and Y-Co interactions are the most important bonding components, but matrix effects are likely responsible for anomalously short Co-Co contacts in the structure. PMID:15792462

Tkachuk, Andriy V; Mar, Arthur

2005-04-01

14

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

PubMed

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

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

2003-12-01

15

Band-gap variation in RScO3 (R=Pr, Nd, Sm, Eu, Gd, Tb, and Dy): X-ray absorption and O K-edge x-ray emission spectroscopies  

NASA Astrophysics Data System (ADS)

The electronic structure of rare-earth scandates RScO3 (R: newly studied Pr, Nd, Eu, and Tb, compared with previously studied Sm, Gd, and Dy) was analyzed by a combined use of O K absorption and emission spectroscopies and Sc L-edge absorption spectroscopy. This permitted the estimation of band gaps by use of a method that differed from optical measurements. The band-gap variation over the series in dependence on the rare-earth ion is analyzed, and a correlation between the Sc-O mean distance and the band gap is found and discussed.

Derks, C.; Kuepper, K.; Raekers, M.; Postnikov, A. V.; Uecker, R.; Yang, W. L.; Neumann, M.

2012-10-01

16

Preparation of a New Phase Having a Cation-Ordered C-Type Rare-Earth Oxide Related Structure in the Systems Bi 2O 3- Ln 2O 3 ( Ln = Sm, Eu, Gd, Tb, and Dy)  

Microsoft Academic Search

A new phase Bi1-xLnxO1.5 has been found in the systems Bi2O3-Ln2O3 (Ln = Sm, Eu, Gd, Tb, and Dy with x = 0.38, 0.375, 0.275-0.40, 0.275-0.35, and 0.30-0.35, respectively). The repetitive long-term solid-state reaction at about 800C has produced the present phase; this phase crystallizes in the cubic system I213 with a ? 11 and Z = 32, has

Akiteru Watanabe; Akiteru

1995-01-01

17

A family of 3d-4f octa-nuclear [Mn(III)(4)Ln(III)(4)] wheels (Ln = Sm, Gd, Tb, Dy, Ho, Er, and Y): synthesis, structure, and magnetism.  

PubMed

We present the syntheses, crystal structures, and magnetochemical characterizations for a family of isostructural [Mn(4)Ln(4)] compounds (Ln = Sm, Gd, Tb, Dy, Ho, Er, and Y). They were prepared from the reactions of formic acid, propionic acid, N-n-butyl-diethanolamine, manganese perchlorate, and lanthanide nitrates under the addition of triethylamine in MeOH. The compounds possess an intriguing hetero-octanuclear wheel structure with four Mn(III) and four Ln(III) ions alternatively arranged in a saddle-like ring, where formate ions act as key carboxylate bridges. In the lattice, the molecules stack into columns in a quasi-hexagonal arrangement. Direct current (dc) magnetic susceptibility measurements indicated the depopulation of the Stark components at low temperature and/or very weak antiferromagnetic interactions between magnetic centers. The zero-field alternating current (ac) susceptibility studies revealed that the compounds containing Sm, Tb, and Dy showed frequency-dependent out-of-phase signals, indicating they are single-molecule magnets (SMMs). Magnetization versus applied dc field sweeps on a single crystal of the Dy compound down to 40 mK exhibited hysteresis depending on temperatures and field sweeping rates, further confirming that the Dy compound is a SMM. The magnetization dynamics of the Sm and Y compounds investigated under dc fields revealed that the relaxation of the Sm compound is considered to be dominated by the two-phonon (Orbach) process while the Y compound displays a multiple relaxation process. PMID:21070004

Li, Mengyuan; Lan, Yanhua; Ako, Ayuk M; Wernsdorfer, Wolfgang; Anson, Christopher E; Buth, Gernot; Powell, Annie K; Wang, Zheming; Gao, Song

2010-12-20

18

Octanuclear {Ln(III)8}(Ln = Gd, Tb, Dy, Ho) macrocyclic complexes in a cyclooctadiene-like conformation: manifestation of slow relaxation of magnetization in the Dy(III) derivative.  

PubMed

The synthesis of a series of macrocyclic, isostructural octanuclear lanthanide complexes [Gd8 (LH2)4 (?-Piv)4 (?(2)-Piv)4 (?-OMe)4]6CH3OH2H2O (1), [Tb8 (LH2)4 (?-Piv)4 (?(2)-Piv)4 (?-OMe)4]4CH3OH4H2O (2), [Dy8(LH2)4 (?-Piv)4 (?(2)-Piv)4 (?-OMe)4]8CH3OH (3), and [Ho8(LH2)4(?-Piv)4 (?(2)-Piv)4 (?-OMe)4]CH3OH4H2O (4) have been achieved, using Ln(III) nitrate salts, pivalic acid, and a new multidentate chelating ligand (2E,N'E)-N'-(3-((bis(2- hydroxyethyl)amino)methyl)-2-hydroxy-5-methylbenzylidene)-2-(hydroxyimino) propane hydrazide (LH5), containing two unsymmetrically disposed arms; one side of the phenol unit is decorated with a diethanolamine group while the other side is a hydrazone that has been built by the condensation reaction involving 2-hydroxyiminopropanehydrazide. All the compounds, 1-4, are neutral and are held by the four [LH2](3-) triply deprotonated chelating ligands. In these complexes all the lanthanide ions are doubly or triply bridged via phenolate, alkoxy, and pivalate oxygens. The metal centers are distributed over the 8 vertices of an octagon, resembling a cyclooctadiene ring core. The details of magnetochemical analysis for complexes 1-4 shows that they exhibit antiferromagnetic interactions between the Ln(3+) ions through the phenoxo, alkoxo, and pivalato bridging groups. None of the compounds exhibits slow relaxation of the magnetization at zero applied direct current (dc) magnetic field, which could be due to the existence of a fast quantum tunneling relaxation of the magnetization (QTM). In the case of 3, the application of a small dc field is enough as to fully or partly suppress the fast and efficient zero-field QTM allowing the observation of slow relaxation above 2 K. PMID:23537281

Chandrasekhar, Vadapalli; Bag, Prasenjit; Colacio, Enrique

2013-04-15

19

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

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 4f5d 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 130157 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 OZr 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.

Zhang, Zhi-Jun, E-mail: zhangzj@mail.sic.ac.cn [Key Laboratory of Transparent Opto-Functional Inorganic Materials of Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai, 200050 (China)] [Key Laboratory of Transparent Opto-Functional Inorganic Materials of Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai, 200050 (China); Lin, Xiao [Key Laboratory of Transparent Opto-Functional Inorganic Materials of Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai, 200050 (China) [Key Laboratory of Transparent Opto-Functional Inorganic Materials of Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai, 200050 (China); Graduate School of Chinese Academy of Science, Beijing, 100039 (China); Zhao, Jing-Tai [Key Laboratory of Transparent Opto-Functional Inorganic Materials of Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai, 200050 (China)] [Key Laboratory of Transparent Opto-Functional Inorganic Materials of Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai, 200050 (China); Zhang, Guo-Bin [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230026 (China)] [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230026 (China)

2013-02-15

20

Synthesis, structure and properties of the oxychalcogenide series A4O4TiSe4 (A=Sm, Gd, Tb, Dy, Ho, Er and Y)  

NASA Astrophysics Data System (ADS)

Seven oxyselenide materials have been synthesised with composition A4O4TiSe4 (A=Sm, Gd-Er, Y) via solid state reactions of A2O3, TiSe2 and Se at 900 C. They are all isostructural with Gd4O4TiSe4. Structures have been refined from powder X-ray diffraction data and have monoclinic C2/m symmetry with unit cell parameters of a?15.7 , b?3.75 , c?9.65 and ??117.5. They contain infinite ribbons of edge-sharing A4O and A3TiO tetrahedra 4 units wide, which are linked by chains of TiSe4O2 edge-sharing octahedra. Compositions A=Gd-Ho, Y are semiconductors with conductivities 1-3 Sm-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 TN.

Tuxworth, A. J.; Evans, J. S. O.

2014-02-01

21

Magnetomechanical damping in cryogenic TbDy  

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

22

Size and shape controllable synthesis and luminescent properties of BaGdF5:Ce3+/Ln3+ (Ln = Sm, Dy, Eu, Tb) nano/submicrocrystals by a facile hydrothermal process.  

PubMed

In this paper, we present a facile and environmentally-friendly hydrothermal process to synthesize BaGdF(5): 2.5 mol% Ce(3+)/2.5 mol% Ln(3+) (Ln = Sm, Dy, Eu and Tb) nano/submicroparticles. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), as well as photoluminescence (PL) spectra are used to characterize the resulting samples. The size, shape, and composition of the products could be tuned just by varying the organic additives and the pH values of the initial reaction solutions. The morphologies for the products include nanospheres, submicrospheres, peanut-like particles, as well as the spindle-like and star-like aggregates. Moreover, the size of the samples can be tuned from 50 nm to 150 nm. Additionally, we systematically investigate the luminescence properties of different lanthanide ions in BaGdF(5) host. Under single-wavelength excitation at 260 nm, the samples doped with different lanthanide ions show intensive multicolor visible emissions depending on the doped Ln(3+) ions. The luminescence process can be attributed to the strong absorption of UV irradiation by Ce(3+) ions, followed by energy transfer to Gd(3+) ions, from which the energy is transferred to Ln(3+), resulting in the emission from the luminescent Ln(3+) centers. The Gd(3+) ions play an intermediate role in this process. PMID:21505713

Yang, Dongmei; Kang, Xiaojiao; Shang, Mengmeng; Li, Guogang; Peng, Chong; Li, Chunxia; Lin, Jun

2011-06-01

23

Size and shape controllable synthesis and luminescent properties of BaGdF5:Ce3+/Ln3+ (Ln = Sm, Dy, Eu, Tb) nano/submicrocrystals by a facile hydrothermal process  

NASA Astrophysics Data System (ADS)

In this paper, we present a facile and environmentally-friendly hydrothermal process to synthesize BaGdF5: 2.5 mol% Ce3+/2.5 mol% Ln3+ (Ln = Sm, Dy, Eu and Tb) nano/submicroparticles. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), as well as photoluminescence (PL) spectra are used to characterize the resulting samples. The size, shape, and composition of the products could be tuned just by varying the organic additives and the pH values of the initial reaction solutions. The morphologies for the products include nanospheres, submicrospheres, peanut-like particles, as well as the spindle-like and star-like aggregates. Moreover, the size of the samples can be tuned from 50 nm to 150 nm. Additionally, we systematically investigate the luminescence properties of different lanthanide ions in BaGdF5 host. Under single-wavelength excitation at 260 nm, the samples doped with different lanthanide ions show intensive multicolor visible emissions depending on the doped Ln3+ ions. The luminescence process can be attributed to the strong absorption of UV irradiation by Ce3+ ions, followed by energy transfer to Gd3+ ions, from which the energy is transferred to Ln3+, resulting in the emission from the luminescent Ln3+ centers. The Gd3+ ions play an intermediate role in this process.

Yang, Dongmei; Kang, Xiaojiao; Shang, Mengmeng; Li, Guogang; Peng, Chong; Li, Chunxia; Lin, Jun

2011-06-01

24

Electronic and magnetic properties of the rare earth intermetallic compounds RRu 4Sn 6 (R=Nd, Sm, Gd, Tb, Dy and Ho)  

NASA Astrophysics Data System (ADS)

A number of compounds of structural formula RRu 4Sn 6 (R=rare-earth element) have previously been reported to form in the tetragonal crystal structure with space group I42m. In this structure the R atoms are well isolated from each other. We embarked on this study to investigate the physical properties and to compare with earlier results obtained on the strongly correlated, low charge-carrier density compound CeRu 4Sn 6. Here we report our results of crystallographic, electrical resistivity, and magnetic studies on this family of compounds. In contrast to the behaviour in CeRu 4Sn 6, magnetic ordering is evident at low temperatures in the compounds with R=Sm, Gd, and Dy, as is evidenced by well-resolved anomalies in the temperature dependence of the electrical resistivity and static magnetic susceptibility.

Koch, N. E.; Strydom, A. M.

25

Atomistic study of rare-earth compounds R2Fe17 (R=Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Lu) and Nd2Fe17Nx  

NASA Astrophysics Data System (ADS)

Pair potentials based on ab initio calculation are used to simulate the structural properties of R2Fe17 (R=Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Lu). The calculated lattice constants of R2Fe17 (R=Ce, Pr, Nd, Sm) with Th2Zn17 structure and R2Fe17 (R=Y, Ho, Er, Tm, Lu) with Th2Ni17 structure are in good agreement with experiment. The site preference of N atoms in Nd2Fe17 and the structure of Nd2Fe17Nx are close to experimental results. Simultaneously, the increase of the Curie temperature of Nd2Fe17Nx with N is explained qualitatively by the exchange interaction model. All the above results indicate that simple pair potentials are valid for studying the structural properties of these kinds of anisotropy materials and some related nitrides.

Hao, Shi-Qiang; Chen, Nan-Xian; Shen, Jiang

2002-07-01

26

Structure and magnetic properties of RFe11.35Nb0.65 and RFe11.35Nb0.65Ny (R=Y, Sm, Gd, Tb, Dy, Ho, Er, and Lu)  

NASA Astrophysics Data System (ADS)

A series of compounds with the ThMn12-type structure, RFe11.35Nb0.65 (R=Y, Sm, Gd, Tb, Dy, Ho, Er, and Lu), were synthesized. The corresponding nitrides, obtained by gas-solid reactions, retained the same structure as their parent compounds, but with a relative volume expansion of 3%. The Nb atoms occupy the 8i sites in the ThMn12 structure. The highest Curie temperatures are 597 K and 773 K for GdFe11.35Nb0.65 and its nitride, respectively. The average iron magnetic moment ?Fe at T=1.5 K is 1.9?B for parent compounds and 2.1?B for the nitrides. By the introduction of nitrogen, the Fe-Fe exchange interaction is much strengthened while the R-Fe exchange interaction is slightly weakened. The enhancement of ?Fe by the influence of interstitial nitrogen is about 11%. The Fe sublattices of RFe11.35Nb0.65 compounds and their nitrides have an easy c-axis anisotropy. At T=1.5 K, the anisotropy constant K1(Fe) is 25.7 K/f.u. for the parent compounds and 21.9 K/f.u. for the nitrides. The reduction of K1(Fe) by the influence of interstitial nitrogen is about 17%. Spin-reorientation transitions were observed in DyFe11.35Nb0.65 and ErFe11.35Nb0.65 compounds. The complex magnetic behavior of RFe11.35Nb0.65 at low temperatures can be explained by exchange and crystal-field-interaction models. The SmFe11.35Nb0.65 compound has an anisotropy field of 10.0 T at room temperature. Its high Curie temperature and magnetization make it a potential candidate for applications as a permanent magnet.

Hu, Bo-Ping; Wang, Kai-Ying; Wang, Yi-Zhong; Wang, Zhen-Xi; Yan, Qi-Wei; Zhang, Pan-Lin; Sun, Xiang-Dong

1995-02-01

27

Synthesis, magnetism and Mssbauer studies of tetranuclear heterometallic {Fe(III)2Ln2}(Ln = Gd, Dy, Tb) complexes: evidence of slow relaxation of magnetization in the terbium analogue.  

PubMed

A new family of tetranuclear heterometallic assemblies, [Fe(III)2Gd2(H2L)4(?(2)-NO3)2]2ClO42CH3OH2H2O (1), [Fe(III)2Dy2(H2L)4(?(2)-NO3)2]2ClO42CH3OH2H2O (2), [Fe(III)2Tb2(H2L)4(?(2)-NO3)2]2ClO42CH3OH2H2O (3), have been synthesized employing a multi-dentate Schiff-base ligand, (E)-2,2'-(2-hydroxy-3-((2-hydroxyphenylimino)methyl)-5-methylbenzylazanediyl)-diethanol (H4L), Fe(ClO4)26H2O, and Ln(III) nitrate salts. These compounds have been structurally characterized by various analytical and spectroscopic techniques. The molecular structures of 1-3 have been confirmed by single crystal X-ray crystallography. All the three complexes contain two Fe(III) ions at the periphery and two Ln(III) ions in the centre. The entire assembly is held together by four doubly deprotonated [LH2](2-) ligands. All the three complexes (1-3) are dicationic in nature and possess an overall Z-type topology. Magnetic measurements reveal the presence of predominant ferromagnetic coupling for all the three compounds at low temperature. The presence of a frequency-dependent out-of-phase signal in the imaginary part of the ac susceptibility plot suggests a slow relaxation of magnetization for 3 (Fe(III)2Tb2). Furthermore, the magnetization dynamics of all the three complexes have been corroborated by Mssbauer spectroscopy. PMID:25248081

Bag, Prasenjit; Goura, Joydeb; Mereacre, Valeriu; Novitchi, Ghenadie; Powell, Annie K; Chandrasekhar, Vadapalli

2014-11-21

28

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

SciTech Connect

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.

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

2009-12-14

29

Ferromagnetism in novel compounds of the R3Pt23Si11 series with heavy rare earth: Gd, Tb, Dy, Ho and Er  

E-print Network

for the saturated moment of the R3+ ions, except for the Gd compound. The esti- mations of the magnetic entropy in equilibrium in the cerium deficient CePt3Si compound [2]. We recently started the investigation of the new susceptibility follows a Curie-Weiss law, fully consistent with a nor- mal trivalent Ce3+ ion. However

Paris-Sud XI, Université de

30

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

SciTech Connect

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

Ivashita, Flvio F.; Biondo, Valdecir; Bellini, Jusmar V.; Paesano, Andrea [Departamento de Fsica, Universidade Estadual de Maring, Av. Colombo 5790, 87.020-900 Maring, PR (Brazil)] [Departamento de Fsica, Universidade Estadual de Maring, Av. Colombo 5790, 87.020-900 Maring, PR (Brazil); Blanco, M. Cecilia; Fuertes, Valeria C.; Pannunzio-Miner, Elisa V. [INFIQC-CONICET, Departamento de Fisicoqumica, Facultad de Ciencias Qumicas, Universidad Nacional de Crdoba, X5000HUA Crdoba (Argentina)] [INFIQC-CONICET, Departamento de Fisicoqumica, Facultad de Ciencias Qumicas, Universidad Nacional de Crdoba, X5000HUA Crdoba (Argentina); Carbonio, Ral E., E-mail: carbonio@fcq.unc.edu.ar [INFIQC-CONICET, Departamento de Fisicoqumica, Facultad de Ciencias Qumicas, Universidad Nacional de Crdoba, X5000HUA Crdoba (Argentina)

2012-09-15

31

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

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.

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

32

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

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.

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

33

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

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.

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

2009-10-15

34

Polyoxopalladates encapsulating yttrium and lanthanide ions, [X(III)Pd(II)12(AsPh)8O32]5- (X=Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu).  

PubMed

A series of novel yttrium- and lanthanide-containing heteropolyoxopalladates have been prepared and isolated as hydrated sodium salts, Na(5)[X(III)Pd(II)(12)(AsPh)(8)O(32)]y H(2)O (X=Y (1), Pr (2), Nd (3), Sm (4), Eu (5), Gd (6), Tb (7), Dy (8), Ho (9), Er (10), Tm (11), Yb (12), Lu (13); y=15-27). The polyanions [X(III)Pd(II)(12)(AsPh)(8)O(32)](5-) consist of a cuboid framework of twelve Pd(II) ions with eight phenylarsonate heterogroups located at the vertices and a central guest ion X. The compounds 1-13 have been prepared in a simple one-pot self-assembly reaction of Pd(CH(3)COO)(2), phenylarsonic acid and the respective salt of the element X in 0.5 M aqueous sodium acetate solution (pH 6.9), and characterized in the solid state by single-crystal X-ray diffraction, elemental and thermogravimetric (TGA) analyses, and IR spectroscopy. It was demonstrated that small, medium, and also large lanthanide ions can be incorporated in the center of the novel heteropolypalladate [X(III)Pd(II)(12)(AsPh)(8)O(32)](5-). The Ln-O bond lengths follow the expected trend decreasing from left to right in the lanthanide series. This indicates that the {Pd(II)(12)O(32)} shell can adjust to the coordination requirements of the encapsulated guest cation. Compounds 3 and 5 were selected for electrochemical studies. Their cyclic voltammetry in a lithium acetate buffer at pH 5.9 showed a Pd(0) deposition process on the glassy carbon electrode surface. Coulometry indicated that all Pd(II) centers were reduced to Pd(0). The film was stable and could be taken out of the deposition medium and characterized in pure pH 5.9 buffer. Magnetic susceptibility and EPR measurements were carried out on 5 and 6. The former was confirmed to be diamagnetic and the latter strongly paramagnetic with a S=7/2 ground state. DFT calculations for some of the polyoxometalates have been also performed. PMID:20589852

Barsukova, Maria; Izarova, Natalya V; Biboum, Rosa Ngo; Keita, Bineta; Nadjo, Louis; Ramachandran, Vasanth; Dalal, Naresh S; Antonova, Nadya S; Carb, Jorge J; Poblet, Josep M; Kortz, Ulrich

2010-08-01

35

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

NASA Astrophysics Data System (ADS)

A series of head-on complexes of lanthanoid containing germanotungstates was isolated from a one pot reaction in an acetate buffer at pH 4.5. This convenient approach brought forward the [{ Ln(CH 3COO)GeW 11O 39(H 2O)} 2] 12- ( Ln=Eu III, Gd III, Tb III, Dy III, Ho III, Er III, Tm III, and Yb III) family with acetate chelators in the rarely observed ?2: ?2- ?1 mode. All compounds were structurally characterized using various solid state analytics, such as single crystal X-ray diffraction, FT-IR spectroscopy, and thermogravimetric analysis. The isostructural polyanions crystallize in the monoclinic system (S.G. P2 1/ c). Temperature-dependent magnetic susceptibility measurements were performed on the Gd III-complex which exhibits near perfect Curie-type behavior.

Hussain, Firasat; Sandriesser, Stefan; Speldrich, Manfred; Patzke, Greta R.

2011-01-01

36

Magnetoelastic vibration damping properties of TbDy alloys  

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

37

Spectroscopic characteristics of GdVO4: Dy3+ crystal  

NASA Astrophysics Data System (ADS)

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.

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

38

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

Seven oxyselenide materials have been synthesised with composition A{sub 4}O{sub 4}TiSe{sub 4} (A=Sm, GdEr, 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 , b?3.75 , c?9.65 and ??117.5. They contain infinite ribbons of edge-sharing A{sub 4}O and A{sub 3}TiO tetrahedra 4 units wide, which are linked by chains of TiSe{sub 4}O{sub 2} edge-sharing octahedra. Compositions A=GdHo, Y are semiconductors with conductivities 13 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=GdHo. 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, GdEr, 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.

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

2014-02-15

39

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

PubMed

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

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

2011-11-01

40

Extreme ultraviolet emission spectra of Gd and Tb ions  

SciTech Connect

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.

Kilbane, D.; O'Sullivan, G. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland)

2010-11-15

41

Thermoluminescence properties of nanophosphors BaSO?:Dy and BaSO?:Tb.  

PubMed

Nanocrystalline BaSO4:Dy and BaSO4:Tb were prepared by the coprecipitation method. The materials were characterized with X-ray diffractometry, UV-visible spectroscopy, and scanning electron microscopy. The glow curves of the BaSO4:Dy and BaSO4:Tb nanophosphors feature main peaks at 505 K and 480 K, respectively. The responses to the (60)Co dose are linear in the range 0.1-1 kGy for BaSO4:Dy and in the range 0.1-7 kGy for BaSO4:Tb. The energy dependences of the responses were also studied. PMID:24035929

Rezaee Ebrahim Saraee, Kadijeh; Aghay Kharieky, Amin

2013-12-01

42

Systematics of low-lying dipole strengths in odd and even Dy and Gd isotopes  

SciTech Connect

Photon scattering experiments on the odd, deformed nuclei {sup 161,163}Dy and {sup 157}Gd provided detailed information on the excitation energies and transition probabilities of low-lying dipole excitations. In the case of the even-even nuclei {sup 162,164}Dy in addition spins and parities of the excited states could be determined model independently by measuring the angular distributions and the linear polarization of the scattered photons using a Compton polarimeter. The results are compared with the systematics obtained for the neighboring even-even isotopes {sup 160}Dy and {sup 156,158,160}Gd in previous photon scattering experiments. Whereas in the odd Dy isotopes a concentration of dipole strength is observed, which fits nicely into the systematics of the orbital {ital M}1 mode, the dipole strength in {sup 157}Gd is completely fragmented into about 90 transitions.

Margraf, J.; Eckert, T.; Rittner, M.; Bauske, I.; Beck, O.; Kneissl, U.; Maser, H.; Pitz, H.H.; Schiller, A. [Institut fuer Strahlenphysik, Universitaet Stuttgart, Allmandring 3, D-70569 Stuttgart (Germany)] [Institut fuer Strahlenphysik, Universitaet Stuttgart, Allmandring 3, D-70569 Stuttgart (Germany); Brentano, P.v.; Fischer, R.; Herzberg, R.; Pietralla, N.; Zilges, A. [Institut fuer Kernphysik, Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln (Germany)] [Institut fuer Kernphysik, Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln (Germany); Friedrichs, H. [Institut fuer Kernphysik, Justus-Liebig-Universitaet Giessen, Leihgesterner Weg 217, D-35392 Giessen (Germany)] [Institut fuer Kernphysik, Justus-Liebig-Universitaet Giessen, Leihgesterner Weg 217, D-35392 Giessen (Germany)

1995-11-01

43

Optical fiber magnetic field sensors with TbDyFe magnetostrictive thin films as sensing materials.  

PubMed

Different from usually-used bulk magnetostrictive materials, magnetostrictive TbDyFe thin films were firstly proposed as sensing materials for fiber-optic magnetic field sensing characterization. By magnetron sputtering process, TbDyFe thin films were deposited on etched side circle of a fiber Bragg Grating (FBG) as sensing element. There exists more than 45pm change of FBG wavelength when magnet field increase up to 50 mT. The response to magnetic field is reversible, and could be applicable for magnetic and current sensing. PMID:19997310

Yang, Minghong; Dai, Jixiang; Zhou, Ciming; Jiang, Desheng

2009-11-01

44

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

PubMed

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

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

2014-08-14

45

(Gd,Yb,Tb)PO4 up-conversion nanocrystals for bimodal luminescence-MR imaging  

NASA Astrophysics Data System (ADS)

Up-conversion (Gd,Yb,Tb)PO4 materials and their potential for bimodal imaging have received little attention in the literature. Herein, we report the first study on the up-conversion emission of (Gd,Yb,Tb)PO4 nanocrystals synthesized via a hydrothermal method at 150 C. These materials exhibit ultraviolet, blue and green up-conversion emissions upon excitation with a 980 nm continuous wave laser diode. The intensity of the blue-emission band at 479 nm, ascribed to the cooperative up-conversion emission of a pair of excited Yb3+ ions, depends on the Yb3+/Tb3+ concentration ratio, calcination temperature and particle size. Strong green up-conversion emission of Tb3+ is observed at 543 nm for the 5D4 --> 7F5 transition. Relaxometry measurements reveal that the nanocrystals are efficient T2-weighted (negative) contrast agents which, combined with visible-light emission generated by infrared excitation, affords them considerable potential for being used in bimodal, photoluminescence-magnetic resonance, imaging.Up-conversion (Gd,Yb,Tb)PO4 materials and their potential for bimodal imaging have received little attention in the literature. Herein, we report the first study on the up-conversion emission of (Gd,Yb,Tb)PO4 nanocrystals synthesized via a hydrothermal method at 150 C. These materials exhibit ultraviolet, blue and green up-conversion emissions upon excitation with a 980 nm continuous wave laser diode. The intensity of the blue-emission band at 479 nm, ascribed to the cooperative up-conversion emission of a pair of excited Yb3+ ions, depends on the Yb3+/Tb3+ concentration ratio, calcination temperature and particle size. Strong green up-conversion emission of Tb3+ is observed at 543 nm for the 5D4 --> 7F5 transition. Relaxometry measurements reveal that the nanocrystals are efficient T2-weighted (negative) contrast agents which, combined with visible-light emission generated by infrared excitation, affords them considerable potential for being used in bimodal, photoluminescence-magnetic resonance, imaging. Electronic supplementary information (ESI) available: A schematic representation for the synthesis of up-conversion monoclinic (Gd,Yb,Tb)PO4 nanocrystals (Fig. S1); XRD patterns of as-synthesized (Gd,Yb,Tb)PO4.2.5H2O and calcined (Gd,Yb,Tb)PO4 samples (Fig. S2) and of dextran-coated and uncoated Gd0.87Yb0.10Tb0.03PO4 nanocrystals (Fig. S3); TEM images of (Gd,Yb,Tb)PO4.2.5H2O and (Gd,Yb,Tb)PO4 samples (Fig. S5 and S6); FT-IR spectra of (Gd,Yb,Tb)PO4.2.5H2O and (Gd,Yb,Tb)PO4 samples (Fig. S7); pump-power dependence of the up-conversion emission intensities (Fig. S8); comparison of the up-conversion emission for dextran-coated and uncoated monoclinic Gd0.87Yb0.10Tb0.03PO4 nanocrystals (Fig. S9); up-conversion emission spectra of monoclinic Gd0.85Yb0.10Tb0.05PO4 nanocrystals calcined for 3 hours at 900 C and 1200 C (Fig. S10); relaxivity measurements (Fig. S11 and S12); UV-visible absorption spectra and calibration curve for the Gd3+ leaching test (Fig. S13); steady-state emission/excitation spectra (Fig. S14). See DOI: 10.1039/c2nr31226c

Debasu, Mengistie L.; Ananias, Duarte; Pinho, Sonia L. C.; Geraldes, Carlos F. G. C.; Carlos, Lus D.; Rocha, Joo

2012-07-01

46

Tb 1- xDy xFe 2/Fe composites: compositional effects on torque response  

NASA Astrophysics Data System (ADS)

Magnetostrictive composites of melt-spun Tb 1- xDy xFe 2 in an Fe matrix spanning the entire Tb-Dy composition range ( x = 0, 0.2, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1) have been prepared by hot pressing. Equal volumes of the two components and identical consolidation procedures were used for each composition. We find that the saturation magnetostriction ?S, a measure of the direct magnetostrictive effect in the composites, decreases monotonically, but not linearly, with increasing Dy content x from 580 ppm for TbFe 2 to 120 ppm for DyFe 2. In contrast, the torque response R? in a ring sensor configuration, which is a measure of the inverse magnetostrictive effect, varies by an order of magnitude over the composition interval and exhibits a peak value of R? = 6 G/100 ppm at x=0.5. This value is almost three times larger than the response of maraging steel in the same sensor configuration. The magnetostrictive ribbon and Fe matrix components of the x=0.5 composite were also examined with phase-contrast magnetic force microscopy (MFM) and atomic force microscopy (AFM).

Pinkerton, F. E.; Herbst, J. F.; Olk, C. H.; Meyer, M. S.; Moleski, J. J.

2002-03-01

47

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

E-print Network

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

Erskine, James L.

48

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

E-print Network

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

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

2015-01-01

49

Yellow laser performance of Dy^3+ in co-doped Dy,Tb:LiLuF_4  

NASA Astrophysics Data System (ADS)

We present laser results obtained from a Dy$^{3+}$-Tb$^{3+}$ co-doped LiLuF$_{4}$ crystal, pumped by a blue emitting InGaN laser diode, aiming for the generation of a compact 578 nm source. We exploit the yellow Dy$^{3+}$ transition $^{4}$F$_{9/2}$ $\\Longrightarrow$ $^{6}$H$_{13/2}$ to generate yellow laser emission. The lifetime of the lower laser level is quenched via energy transfer to co-doped Tb$^{3+}$ ions in the fluoride crystal. We report the growth technique, spectroscopic study and room temperature continuous wave (cw) laser results in a hemispherical cavity at 574 nm and with a highly reflective output coupler at 578 nm. A yellow laser at 578 nm is very relevant for metrological applications, in particular for pumping of the forbidden $^{1}$S$_{0} \\Longrightarrow ^{3}$P$_{0}$ Ytterbium clock transition, which is recommended as a secondary representation of the second in the international system (SI) of units. This paper was published in Optics Letters and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OL.39.006628. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.

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

2014-12-01

50

Microstructure, mechanical and corrosion properties of Mg-Dy-Gd-Zr alloys for medical applications.  

PubMed

In previous investigations, a Mg-10Dy (wt.%) alloy with a good combination of corrosion resistance and cytocompatibility showed great potential for use as a biodegradable implant material. However, the mechanical properties of Mg-10Dy alloy are not satisfactory. In order to allow the tailoring of mechanical properties required for various medical applications, four Mg-10(Dy+Gd)-0.2Zr (wt.%) alloys were investigated with respect to microstructure, mechanical and corrosion properties. With the increase in Gd content, the number of second-phase particles increased in the as-cast alloys, and the age-hardening response increased at 200C. The yield strength increased, while the ductility reduced, especially for peak-aged alloys with the addition of Gd. Additionally, with increasing Gd content, the corrosion rate increased in the as-cast condition owing to the galvanic effect, but all the alloys had a similar corrosion rate (~0.5 mm year(-1)) in solution-treated and aged condition. PMID:23523938

Yang, L; Huang, Y; Feyerabend, F; Willumeit, R; Mendis, C; Kainer, K U; Hort, N

2013-11-01

51

Formation and magnetic properties of TbCu7-type RFe7 compounds and their nitrides (R=Tb and Dy)  

NASA Astrophysics Data System (ADS)

DyFex and TbFex alloys with x=7, 7.7, and 9 were mechanically alloyed followed by annealing in an attempt to prepare TbCu7-type DyFe7 and TbFe7 compounds. X-ray-diffraction and thermomagnetic measurements show that single-phase TbCu7-type TbFe7 can be obtained for all three compositions, while DyFe7 was formed for x=7.7 and 9 when annealed in the temperature range from 650 to 850 C. The Curie temperature (Tc) of the TbCu7-type phase shows no obvious variation with Fe content, but decreases with annealing temperature. For DyFe7.7 and TbFe7.7, their respective Curie temperatures are reduced from 160 and 185 C by annealing at 700 C for 3 h to 140 and 160 C after annealing at 850 C for 3 h. Magnetometry measurements reveal that the TbCu7-type phase is a soft phase with a room-temperature coercivity of less than 500 Oe. Nitriding the TbCu7-type phase results in lattice expansions without changing the crystal structure. However, nitriding increases the Curie temperatures dramatically to 465 and 450 C for TbFe7.7Ny and DyFe7.7Ny, respectively. Furthermore, nitriding greatly enhanced the coercivities of TbCu7-type compounds, reaching values of 3.75 and 4.0 kOe for TbFe7.7Ny and DyFe7.7Ny, respectively. The nitrides with optimum coercivities are single-phase TbCu7-type compounds with an average grain size of 10-15 nm as estimated from Bragg peak broadening. A coercivity mechanism based on contributions from the random anisotropy of the R3+ ions and the crystalline anisotropy is proposed to explain the observed effects.

Yang, Jun; Mao, Ou; Altounian, Z.

1997-04-01

52

Color-tunable emission and energy transfer studies in GdOBr:Ce3+ Dy3+ phosphor  

NASA Astrophysics Data System (ADS)

Color-tunable blue to bluish white-emitting Ce3+/Dy3+ co-doped GdOBr phosphors have been synthesized by the conventional solid-state method. The phase structures, luminescent properties and energy transfer process were discussed in detail. Broad-band absorption originating from the f-d transition of Ce3+ can be found for the as-prepared GdOBr:Ce3+,Dy3+ phosphor, and color-tunable blue to bluish white emission can be realized owing to the energy transfer between Ce3+ and Dy3+. The energy transfer mechanism is demonstrated to be the dipole-dipole process. The energy transfer efficiency increases with increasing Dy3+ concentrations. The results indicate that Ce3+/Dy3+-activated GdOBr phosphors may be potential for phosphor-converted white-light UV-LEDs.

Li, Molin; Xia, Zhiguo; Wang, Ziyuan

2014-11-01

53

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

PubMed

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

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

2014-03-01

54

Magnetic behaviour of Tb impurities in Gd andY single crystals: a nuclear orientation study  

NASA Astrophysics Data System (ADS)

The low temperature nuclear orientation of160Tb impurities in Gd andY single crystals has been studied in the temperature range 7 40 mK andin the external magnetic field range 0 7.3 T applied along a-, b- and c-crystal axes. In the case of Tb in Gd we found a considerable noncollinearity of the Tb magnetic moment with respect to the magnetic external field direction even for high B ext. In the case of Tb in Y the results cannot be described by a simple model, taking into account the simultaneous influence of the crystal andexternal magnetic fields. Some new proposals for interpretation of the experimental dat are given.

Trhlk, M.; Brewer, W. D.; Kuriplach, J.; Sedlk, B.; Dupk, J.

1993-03-01

55

Fiber optic magnetic field sensor based on the TbDyFe rod  

NASA Astrophysics Data System (ADS)

We present, and experimentally demonstrate, a fiber optic magnetic field sensor for the measurement of a weak alternating magnetic field, based on a TbDyFe rod. The fiber optic magnetic field sensor is constructed in a Michelson interferometer configuration, and the phase-generated carrier demodulation is used to obtain the time-varying phase shift induced by the applied magnetic field. A high sensitivity of up to 3.6 10-2 V ?T - 1 (rms) with a resolution of 23 pT/?Hz (rms) at 50 Hz is achieved. Experimental results show that the sensor exhibits excellent linearity and reversibility.

Chen, Feifei; Jiang, Yi

2014-08-01

56

Multicolor tunable luminescence and paramagnetic properties of NaGdF?:Tb?/Sm? multifunctional nanomaterials.  

PubMed

Tb(3+) and/or Sm(3+) doped NaGdF4 luminescent nanomaterials have been successfully synthesized by an SDS-assisted one-step hydrothermal method. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray energy dispersive spectrometer (EDS), photoluminescence (PL) spectra and a vibrating sample magnetometer (VSM). The results show that the synthesized samples are all pure ?-NaGdF4. The as-prepared Tb(3+) or Sm(3+) doped samples show strong green and yellow emission, originating from the allowed (5)D3?(7)F(J) (J = 5, 4, 3, 2) and (5)D4?(7)F(J) (J = 6, 5, 4, 3) transitions of the Tb(3+) ions and the (4)G(5/2)?(6)H(5/2), (6)H(7/2), (6)H(9/2) transition of the Sm(3+) ions. Based on the excitation wavelengths, multiple (yellowish green, yellow, white) emissions are obtained by Sm(3+) ion co-activated NaGdF4:Tb(3+) phosphors. Moreover, an energy transfer from Tb(3+) to Sm(3+) is observed, which is justified through the luminescence spectra and the fluorescence decay curves. Furthermore, the resonance-type energy transfer from Tb(3+) to Sm(3+) is demonstrated to occur via the dipole-dipole mechanism. In addition, the obtained samples also exhibit paramagnetic properties at room temperature. It is obvious that these multifunctional Tb(3+), Sm(3+) co-doped ?-NaGdF4 nanomaterials, with tunable multicolors and intrinsic paramagnetic properties, may have potential application in the fields of full-color displays, biological labels, bioseparation and magnetic resonance imaging. PMID:24882267

Guan, Hongxia; Liu, Guixia; Wang, Jinxian; Dong, Xiangting; Yu, Wensheng

2014-07-28

57

Hyperfine interactions in R x Gd1 - x Fe3 intermetallics R = Tb, Y  

NASA Astrophysics Data System (ADS)

The structural and magnetic properties of rare earth iron intermetallic compounds Tb x Gd1- x Fe3 and Y x Gd1- x Fe3 ( x = 0. 0, 0. 1, 0. 2, 0. 4, 0. 5, 0. 6, 0. 8, 1. 0) was studied by X-ray diffraction, the 57Fe Mssbauer effect and SQUID measurements. All investigated compounds crystallize in the rhombohedral PuNi3-type of crystal structure. The investigation of magnetic properties of R x Gd1- x Fe3 proved their ferrimagnetic behavior. The Curie temperature of the investigated compounds decreases with the increase of R concentration from 721K (GdFe3) to 655K (TbFe3) and 533K (YFe3). The saturation magnetic moment MS in the R x Gd 1- x Fe3 system increase with x parameter. The Mssbauer spectra are analyzed using four sextets, corresponding to three crystallographically (b, c, h) and four magnetically (b, c, h1, h2) inequivalent sites for iron. The mean hyperfine magnetic field increases with increase of the Gd concentration

Ka?zio?ka-Gawe?, M.; Bajorek, A.

2014-04-01

58

Magnetic properties of NiFe2-xRExO4 (RE=Dy, Gd) using magnetic Compton scattering  

NASA Astrophysics Data System (ADS)

Temperature dependent spin momentum densities of NiFe2-xRExO4 (x=0, 0.05; RE=Dy, Gd) ferrites have been measured using a magnetic Compton spectrometer available at SPring-8, Japan. The experimental profiles of NiFe2O4 (NFO) with doping of Dy and Gd show almost similar spin moment as of undoped NFO. The contribution of different constituents in the formation of total spin moment is also deduced from the analysis of Compton line shape. It is seen that 5% doping of Dy3+ or Gd3+ ions at Fe3+ sites leads to a redistribution of spin moment at Fe3+ and RE3+ sites. The magnetic Compton data when compared with the magnetization data (using a vibrating sample magnetometer) show almost a constant orbital moment (0.210.03 B/f.u.) in the doped and undoped NFO.

Sahariya, Jagrati; Mund, H. S.; Sharma, Arvind; Dashora, Alpa; Itou, M.; Sakurai, Y.; Ahuja, B. L.

2014-06-01

59

Magnetostriction of single crystal and polycrystalline Tb0.60Dy0.40 at cryogenic temperatures  

NASA Astrophysics Data System (ADS)

At cryogenic temperatures, single crystals of TbDy alloys exhibit giant magnetostrictions of nearly 9000 ppm, making these materials promising for engineering service in cryogenic actuators, valves, and positioners. The preparation of single crystals is difficult and costly. Preliminary results on the magnetostriction of textured polycrystalline materials are presented here. For instance, polycrystalline Tb0.60Dy0.40, plane-rolled (one direction of applied stress) to induce crystallographic texture, has shown magnetostrictions at 77 K of 3000 ppm for an applied field of 4.5 kOe and an applied load of 23 MPa, or 48% that of a single crystal under similar conditions. Comparisons are presented between the magnetostrictive response of plane- and form-rolled (two orthogonal directions of applied stress) polycrystalline Tb0.60Dy0.40 at 10 and 77 K. It is reported that at 10 K plane-rolled Tb0.60Dy0.40 exhibits 1600 ppm magnetostriction at an applied field of 4.4 kOe with a minimal applied load of 0.28 MPa. An observed restoration of the initial unstrained state may be a useful feature of polycrystalline materials for engineering service. Finally it is reported that thermal expansion measurements provide a measure of crystallographic texture for comparison with the magnetostriction.

Dooley, J. A.; Lindensmith, C. A.; Chave, R. G.; Good, N.; Graetz, J.; Fultz, B.

1999-04-01

60

Optical properties and Judd-Ofelt parameters of Dy3+ doped K2GdF5 single crystal  

NASA Astrophysics Data System (ADS)

Dy3+-doped K2GdF5 single crystals with 10.0 mol% have been prepared by hydrothermal condition. The spectra are analyzed in term of the Judd-Ofelt theory, the intensity parameters (??, ? = 2, 4, 6) have been evaluated for Dy3+-doped K2GdF5 sample. The electric (Sed), magnetic (Smd) dipole line strength, radiative (A), and total radiative (AT) transition probabilities, lifetime (?R), branching ratios (?R) for the excited levels of Dy3+ doped K2GdF5 crystals were investigated by using the intensity parameters. In addition, the stimulated emission cross-sections (??p) and integrated emission cross-section (?if) have been predicted for the transitions from excited level, 4F9/2, to the 6H15/2, 6H13/2 and 6H11/2 levels. The energy transfer occurs from Gd3+ to Dy3+, resulting in the additional intense excitation UV-narrow bands for the luminescence of the Dy3+ ions.

Van Do, Phan; Tuyen, Vu Phi; Quang, Vu Xuan; Thanh, Nguyen Trong; Ha, Vu Thi Thai; Van Tuyen, Ho; Khaidukov, Nicholas M.; Marcazz, Julin; Lee, Yong-Ill; Huy, Bui The

2013-07-01

61

Lattice vibrations of AVO4 crystals (A = Lu, Yb, Dy, Tb, Ce)  

NASA Astrophysics Data System (ADS)

A short range force constant model has been applied using normal coordinates to investigate the Raman and the infrared wavenumbers in rare earth AVO4 compounds (A = Lu, Yb, Dy, Tb, Ce) having space group I41/a and symmetry C4h6. The calculation of zone center phonons has been made by using four stretching and five bending force constants. The calculated Raman and infrared wavenumbers are in very good agreement with the observed ones. The present calculations interpret reasonably the mode assignment of 779 cm-1 as Eg mode and 853 cm-1 as Ag mode in case of LuVO4, which were assigned differently in earlier observation. The potential energy distribution has also been investigated for determining the significance of contribution from each force constant toward the Raman and the infrared wavenumbers.

Jindal, Ruby; Sinha, M. M.; Gupta, H. C.

2013-09-01

62

Brilliant Sm, Eu, Tb, and Dy Chiral Lanthanide Complexes with Strong Circularly Polarized Luminescence  

PubMed Central

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, glum, 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. PMID:17199285

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

2009-01-01

63

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

SciTech Connect

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.

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

64

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

SciTech Connect

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}.

Masnavi, Majid; Szilagyi, John; Parchamy, Homaira; Richardson, Martin C. [The Townes Laser Institute, College of Optics and Photonics, University of Central Florida, 4000 Central Florida Blvd., Orlando, Florida 32816 (United States)] [The Townes Laser Institute, College of Optics and Photonics, University of Central Florida, 4000 Central Florida Blvd., Orlando, Florida 32816 (United States)

2013-04-22

65

Resonant photoemission of single-crystal RBa Co2 O5+? ( R=Gd , Dy)  

NASA Astrophysics Data System (ADS)

Resonant photoemission of single crystals of the double perovskites GdBaCo2O5+? and DyBaCo2O5+? has been carried out at the UK Synchrotron Radiation Source at Daresbury. The resonance onset energy at the Co 3p?3d threshold is used to explore the Co spin state in the double perovskites as a function of temperature. In contrast with the simple perovskites LaCoO3 and HoCoO3 , an undelayed resonance is observed for GdBaCo2O5+? and DyBaCo2O5+? at temperatures as low as 50 K, consistent with the idea that the Co spin state in the pyramidal sites of the double perovskites does not fluctuate with temperature. The temperature variation of the data suggest that the phase transition observed in GdBaCo2O5+? at around 350 K is not associated with a sudden low spin-high spin switch in the octahedral sites. The giant rare earth (R) 4d?4f resonances are also probed, and are used to identify the 4f contributions to the valence band. This shows that the density of states close to the Fermi energy for all materials is of Co 3d/O2p character, with no R4f contribution. Comparison is made with LSDA+U calculations. Our experiments indicate that the spin equilibrium in the double perovskites is significantly shifted in favor of higher spin multiplicities compared with materials such as LaCoO3 .

Flavell, W. R.; Thomas, A. G.; Tsoutsou, D.; Mallick, A. K.; North, M.; Seddon, E. A.; Cacho, C.; Malins, A. E. R.; Patel, S.; Stockbauer, R. L.; Kurtz, R. L.; Sprunger, P. T.; Barilo, S. N.; Shiryaev, S. V.; Bychkov, G. L.

2004-12-01

66

Search for the soft mode phonons in TbMnO3, TbMn2O5, and DyMn2O5 multiferroics using Raman and Far Infrared Transmission Spectroscopy  

Microsoft Academic Search

One of the possible explanations of the anomalies in the dielectric properties of TbMnO3 and TbMn2O5 multiferroics [Nature 426, 55 (2003) and Nature 429, 392 (2004)] is the phonon softening. Raman spectra of the optical phonons in TbMnO3, TbMn2O5, and DyMn2O5 single crystals have been measured in the temperature range between 4 and 300 K and in the magnetic field

A. A. Sirenko; C. Ulrich; G. L. Carr

2005-01-01

67

Host-Sensitized Luminescence Properties in CaNb2O6:Ln(3+) (Ln(3+) = Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+)) Phosphors with Abundant Colors.  

PubMed

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

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

2015-01-01

68

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

SciTech Connect

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

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

2012-08-15

69

Possible Antiferro-Octupolar Order in Antiferromagnetic TbB2C2 Examined by Gd Substitution  

NASA Astrophysics Data System (ADS)

We have examined the effects of Gd substitution on the anomalous antiferromagnetic (AFM) properties of TbB2C2 having field-induced antiferro-quadrupolar (AFQ) ordered phases. The Gd substitution induces drastic changes in the magnetic properties. The AFM structure characteristic to TbB2C2, the anomalous increase in magnetic susceptibility below TN, and the strong preference of AFM domains disappear with the substitution of low Gd content of less than 10%. We propose a promising assumption that an antiferro-octupolar (AFO) ordering occurs at TN simultaneously with AFM ordering in TbB2C2. The fragility of anomalous properties originates in the fragility of the antiferro-octupolar interaction against the substitution of Gd3+ ions with L=0.

Matsuoka, Eiichi; Sasaki, Yuta; Usui, Daichi; Nakagawa, Masaaki; Onodera, Hideya

2006-12-01

70

Anomalous weak ferromagnetism in the magnetically frustrated system R1 -xYxB4 (R =Tb and Dy)  

NASA Astrophysics Data System (ADS)

The magnetic properties of R1 -xYxB4 (R =Tb and Dy) single crystals were investigated. As the concentration of Y increased, the antiferromagnetic transition temperature was observed to systematically decrease, and an exotic weak ferromagnetic transition was also observed at the antiferromagnetic transition temperature. The weak ferromagnetism occurred in the magnetic easy plane, (001) for Tb1-xYxB4 , and along the magnetic easy axis, [001] for Dy1-xYxB4 . For Tb1-xYxB4 , the saturated ferromagnetic signal at T =2 K was also anisotropic, even in the (001) plane; that is, there was a local maximum along the principal axis and a local minimum along the [110] axis (equivalent to those along Tb dimers), where the parent compound, TbB4, was characterized as a magnetically frustrated dimer in a Shastry-Sutherland lattice. In addition, the saturated signal exhibited a strong dependence on the Y concentration, i.e., the signal reached a maximum at x ?0.35 , indicating that the emergence of the weak ferromagnetism is not due to an individual atomic effect but rather to a collective correlation effect. This is an experimental observation of the development of weak ferromagnetism in a magnetically frustrated system induced by replacing a magnetic element with a nonmagnetic element.

Kang, B. Y.; Kim, J. Y.; Choi, H. Y.; Cho, B. K.

2015-01-01

71

Pressure effect on the isostructural transition in RNiAl compounds (R=Tb and Gd)  

NASA Astrophysics Data System (ADS)

We have studied the presence of a gap of forbidden c/a values for the hexagonal crystal structure of TbNiAl and GdNiAl, appearing in the whole family of the RTAl compounds (R-rare earth, T-transition metal). TbNiAl and GdNiAl both exhibit a first-order structural transition at low temperatures around 100 K and 205 K, respectively. We have for the first time studied this structural step upon application of hydrostatic pressure on both compounds. An unusually rapid decrease of the critical temperature with pressure was found. The decrease is furthermore steeper for GdNiAl in which the transition appears at higher temperature at ambient pressure. Common property for both studied compounds is preference of the c/a ratio below the critical forbidden interval after application of pressure, due to weaker interplanar chemical bonding in the layered ZrNiAl-type of crystal structure.

Prchal, J.; Klicpera, M.; Doleal, P.; Katil, J.; Mek, M.; Javorsk, P.

2014-05-01

72

Investigation of Structure of Gd and Tb Nuclei using STARS and LiBerACE  

NASA Astrophysics Data System (ADS)

This experiment, performed at Livermore Berkeley National Lab as a collaboration of Livermore, Berkeley, and the University of Richmond, was designed to investigate the structure of gadolinium and terbium nuclei using the P + 156Gd reaction at E beam = 27 MeV. The experimental design included use of the STARS system for detecting charged particles as well as the LiBerACE clover array for detecting gamma rays. The master gate was set to record particle-gamma as well as gamma-gamma coincidences. The data is currently being analyzed using the RADWARE escl8r software package which has allowed the creation of extensive level schemes for several Gd and Tb nuclei. So far the data suggests new gamma ray transitions as well as new energy states in 154Gd and 155Tb. The project is ongoing, and the results will be presented. This work was supported by the US Department of Energy under grant numbers DE-FG52NA26206 and DE-FG02-05ER41379.

Bonniwell, Cain; Pauerstein, Ben; Allmond, J. M.; Beausang, C. W.

2009-10-01

73

Structural, magnetic, and magnetothermal properties of R{sub 2}Co{sub 2}Al (R = Tb, and Dy) compounds  

SciTech Connect

The Tb{sub 2}Co{sub 2}Al and Dy{sub 2}Co{sub 2}Al alloys prepared in this study consist of 2:2:1 and 1:1:1 phases, which were identified by using the powder x-ray diffraction and scanning electron microscopy techniques. Considerable thermomagnetic irreversibility between the zero field cooled and field cooling magnetization were observed in the two alloys because of the energy barriers needed to overcome the alignment of domains. Remarkable intrinsic coercivity and remanence at temperatures close to absolute zero were also observed. The maximum magnetic entropy changes of the Tb{sub 2}Co{sub 2}Al and Dy{sub 2}Co{sub 2}Al alloys are 6.4 J/kg K and 10.6 J/kg K, respectively, with a field change from 0 to 50 kOe. The low magnetic entropy changes result from the low magnetization of the alloys even with a 50 kOe of applied field. - Research Highlights: {yields} Two-phase structure was observed in the heat treated R{sub 2}Co{sub 2}Al (R = Tb, and Dy) alloys. {yields} Considerable irreversibility was observed between the ZFC and FC magnetization. {yields} Intrinsic, remarkable coercivity and remanence were also observed. {yields} Relatively low magnetic entropy changes were obtained and reasons are given.

Fu, H., E-mail: fuhao@uestc.edu.cn [Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Ames Laboratory, U.S. Department of Energy, Iowa State University, Ames, IA 50011-3020 (United States); Zou, M. [Ames Laboratory, U.S. Department of Energy, Iowa State University, Ames, IA 50011-3020 (United States); Guo, M.S.; Zheng, Q.; Zu, X.T. [Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu 610054 (China)

2011-04-15

74

Spin-dependent photoabsorption at the L -edges of ferromagnetic Gd and Tb metal  

Microsoft Academic Search

The spin-dependent absorption of circularly polarized x-rays is studied at theL-edges of ferromagnetic Gd and Tb metal. At theL1-edge a spin-dependent part of the absorption coefficient of 10-310-2 is observed. Strong resonance absorption known as white line occurs at theL2- andL3-absorption onset. Correlated with it one finds large spin-dependent absorption effects with amplitudes of a few percent. The spin-dependent absorption

G. Schtz; M. Knlle; R. Wienke; W. Wilhelm; W. Wagner; P. Kienle; R. Frahm

1988-01-01

75

Optimization of magnetic properties of sintered (SmGdDy)(Co, Fe, Cu, Zr)z magnets by Dy-Co addition  

NASA Astrophysics Data System (ADS)

Liquid phase sintering is used to optimize the magnetic properties and temperature stability of (SmGdDy)(Co, Fe, Cu, Zr)z sintered magnet. DyCo0.51 and Sm0.67Dy0.11Gd0.22(Co0.693Fe0.201Cu0.081Zr0.0252)7.94 alloys are chosen as liquid phase and main phase, respectively. (SmGdDy)(Co, Fe, Cu, Zr)z permanent magnets are prepared with different content of liquid phase. XRD analysis shows that all magnets consist of Th2Zn17-type phase and CaCu5-type phase. Cellular structure studies indicate that the H1-5 cell boundary phase shifts gradually from thin and part of discontinuous to thick and continuous. The cell size decreases with the increase of the content of liquid phase. In addition, the Cu content in cell boundary phase is getting lower with the increase of LP adding ratio. The homogeneous and continuous cellular structure is got when the adding ratio of liquid phase is 3 wt% and the highest intrinsic coercivity is achieved at room temperature (23.88 kOe) and 200 C (12.06 kOe). It's interesting to find that temperature dependence of remanence (?) and the temperature dependence of intrinsic coercivity (?) can be optimized with the increase of the content of liquid phase, in which the ?(20-100 C) and ?(20-200 C) are -0.0075%/C and -0.140%/C for the magnet with 5 wt% liquid phase, and -0.016%/C and -0.322%/C for the magnet with 1 wt% liquid phase.

Liu, L.; Pan, D. L.; Liu, Z.; Zhang, H. W.; Li, M.; Chen, R. J.; Liu, X. M.; Yan, A. R.; Lee, Don; Li, W.

2015-01-01

76

Preparation, characterization, magnetic susceptibility (Eu, Gd and Sm) and XPS studies of Ln2ZrTiO 7 ( Ln=La, Eu, Dy and Gd)  

NASA Astrophysics Data System (ADS)

Bulk and nanosized pyrochlore materials Ln2ZrTiO 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 ( ?) measurements of Gd 2ZrTiO 7, Sm 2ZrTiO 7 and Eu 2ZrTiO 7 were carried out by vibrating sample magnetometer in the temperature range 2-320 K. The variation of ?-1 (or ?) with temperature of Gd 2ZrTiO 7, Sm 2ZrTiO 7 and Eu 2ZrTiO 7 follows the Curie law, intermediate formula and the Curie-Weiss law, respectively. From the linear portion of ?T vs. T-1 plot of Eu 2ZrTiO 7 from 2 to 15 K, the classical nearest neighbor exchange ( Jcl) and dipolar interactions ( Dnn) are obtained. The XPS of Ln2ZrTiO 7 ( Ln=La, Eu, Dy and Gd) gave characteristic peaks for Ln, Ti, Zr and O. The satellite peaks are observed only for 3 d La of La 2ZrTiO 7.

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

2011-02-01

77

Luminescence properties and energy transfer investigations of Sr3Gd(PO4)3:Ce3+,Tb3+ phosphors  

NASA Astrophysics Data System (ADS)

Ce3+ and Tb3+ co-doped Sr3Gd(PO4)3 phosphors were synthesized by the solid-state method. The phase structure and luminescence properties of the phosphor samples were characterized by using powder X-ray diffraction (XRD), photoluminescence (PL) excitation and emission spectra, decay time, respectively. The obtained phosphor exhibits a strong excitation band between 200 and 400 nm, matching well with the dominant emission band of a ultraviolet (UV) light-emitting-diode (LED) chip. Effective energy transfer occurred from Ce3+ to Tb3+ in Sr3Gd(PO4)3 hosts due to the spectra overlap between the PL emission spectrum of Ce3+ ion and the PL excitation spectrum of Tb3+ ion. The energy transfer from Ce3+ and Tb3+ in Sr3Gd(PO4)3 host was demonstrated to be resonant type via a dipole-dipole interaction mechanism with the energy transfer critical distance of 1.87 nm. Furthermore, Sr3Gd(PO4)3:Ce3+,xTb3 can be systematically tuned to generate blue light to yellow-greenish light under UV excitation. It can serve as a potential color-tunable UV phosphor for white-light LED (w-LEDS) devices.

Sun, Jiayue; Sun, Yining; Junhuizeng; Du, Haiyan

2013-07-01

78

Microstructure and mechanical properties of MgGdDyZn alloy with long period stacking ordered structure or stacking faults  

Microsoft Academic Search

The Mg6.5Gd2.5Dy1.8Zn (wt.%) alloy with high strength and ductility was prepared by conventional casting method. At room temperature, the as-cast alloy with 14H long period stacking ordered (LPSO) structure exhibits an ultimate tensile strength of 276MPa and elongation to failure of 10.8%, while they are 392MPa and 6.1% for the peak-aged alloy with basal plane stacking faults (SF). The results

Jinghuai Zhang; Zhe Leng; Shujuan Liu; Jiqing Li; Milin Zhang; Ruizhi Wu

2011-01-01

79

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

SciTech Connect

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.

Evangelisti, Marco [Instituto de Ciencia de Materiales de Aragon (ICMA), Spain; Sorop, Tibi G [Leiden University; Bakharev, Oleg N [Leiden University; Visser, Dirk [ISIS Facility, Rutherford Appleton Laboratory; Hillier, Adrian D. [ISIS Facility, Rutherford Appleton Laboratory; Alonso, Juan [Universidad de Malaga, Spain; Haase, Markus [University of Osnabruck, Barbarastr Germany; Boatner, Lynn A [ORNL; De Jongh, L. Jos [Leiden University

2011-01-01

80

Magnetic order in hybrid frustrated magnets Gd(2-x)Tb(x)Ti2O7 (x = 0.2 and 0.5).  

PubMed

We report on the specific heat, magnetization and ac susceptibility measurements of single crystals of hybrid frustrated magnets Gd(1.8)Tb(0.2)Ti(2)O(7) and Gd(1.5)Tb(0.5)Ti(2)O(7). The analysis of experimental data revealed that, although partial replacing of the Gd(3+) ions by the Tb(3+) ions in the Gd(2)Ti(2)O(7) host lattice slightly enhances antiferromagnetic coupling, as inferred from the evolution of the paramagnetic Curie-Weiss temperature, the ordering temperature gradually decreases. Paramagnetic correlations introduced by the Tb(3+) ions cause this perturbation, altering the effective further neighbor interactions and destabilizing the ground state in Gd(2)Ti(2)O(7). In addition, the low-energy states of Gd(2-x)Tb(x)Ti(2)O(7) are suggested to possess a nature different from those in parent members Tb(2)Ti(2)O(7) and Gd(2)Ti(2)O(7). Finally, the frequency-dependent magnetic susceptibility behavior in Gd(1.5)Tb(0.5)Ti(2)O(7) is consistent with the formation of a spin-glass-like state indicating a pronounced slowing down of the dynamical response of the studied hybrid magnets. PMID:22499160

Orend?, M; Vrbel, P; Orend?ov, A; Prokleka, J; Sechovsk, V; Singh, S; Suryanarayanan, R; Revcolevschi, A

2012-05-01

81

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

NASA Astrophysics Data System (ADS)

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 , 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.

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

82

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

NASA Astrophysics Data System (ADS)

Structural, Mssbauer studies and improved electrical characteristics of Sm, Gd and Dy doped Ni ferrite materials in comparison to that of pure NiFe2O4 are reported. Pure NiFe2O4 crystallizes in inverse spinel phase without any impurity phase. NiFe1.925Sm0.075O4, NiFe1.925Gd0.075O4 and NiFe1.925Dy0.075O4 compounds crystallize in the cubic inverse spinel phase with a very small amount of RFeO3 as additional phase. The back scattered electron imaging analysis indicates the primary and secondary phase formation in NiFe1.925Sm0.075O4, NiFe1.925Gd0.075O4 and NiFe1.925Dy0.075O4 compounds. The room temperature DC resistivity values of NiFe2O4, NiFe1.925Sm0.075O4, NiFe1.925Gd0.075O4 and NiFe1.925Dy0.075O4 compounds are found to be 17107 ? cm, 162107 ? cm, 171107 ? cm and 305107 ? cm respectively. The AC resistivity values (at 1 KHz) of NiFe2O4, NiFe1.925Sm0.075O4, NiFe1.925Gd0.075O4 and NiFe1.925Dy0.075O4 materials are 10105 ? cm, 77105 ? cm, 147105 ? cm and 251105 ? cm, respectively. Temperature dependent electrical resistivity curves reveal two different types of conduction mechanisms. The hyperfine parameters viz., the hyperfine magnetic field, the isomer shift and the quadrupole splitting confirms the substitutions of R3+ ions at B site and their effects on superexchange interactions and structural distortion. The enhanced electrical resistivity of rare earth doped Ni ferrite suggest that tuning properties for desired high frequency applications can be achieved by controlling the doping element and their amount.

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

2014-03-01

83

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

SciTech Connect

Spectroscopic investigations of the rare earth elements Tb, Dy and Ho have been carried out using laser resonance ionization mass spectroscopy. A variety of new intermediate energy levels and autoionizing states were observed in these elements. Efficient and selective excitation and ionization schemes for the elements have been developed for Ti:Sapphire lasers using the spectroscopic data. Resonant ionization schemes for Np were also been studied as the preparation work for related investigations on actinide elements and for the spectroscopy on the heaviest elements, where spectroscopic data so far are scarce or not existing at all.

Gottwald, T.; Mattolat, C.; Raeder, S.; Wendt, K. [Johannes-Gutenberg Universitaet Mainz, Institut fuer Physik, Staudinger Weg 7, 55128 Mainz (Germany); Lassen, J. [TRIUMF-Accelerator Division, 4004 Wesbrook Mall, Vancouver BC, V6T 2A3 (Canada); Liu, Y. [Physics Divison, Oak Ridge National Laboratory, Oak Ridge TN (United States)

2009-03-17

84

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

SciTech Connect

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.

Blake, G.R. [ISIS Facility, Rutherford Appleton Laboratory-CCLRC, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom); Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Chapon, L.C. [ISIS Facility, Rutherford Appleton Laboratory-CCLRC, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom); Radaelli, P.G. [ISIS Facility, Rutherford Appleton Laboratory-CCLRC, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom); Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Park, S.; Hur, N.; Cheong, S-W. [Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854 (United States); Rodriguez-Carvajal, J. [Laboratoire Leon Brillouin (CEA-CNRS), CEA/Saclay, 91191 Gif-sur-Yvette Cedex (France)

2005-06-01

85

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

SciTech Connect

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.

Gottwald, T. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Lassen, J. [TRIUMF, Canada; Liu, Yuan [ORNL; Mattolat, C. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Raeder, S. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Wendt, K. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany

2009-03-01

86

Neutron powder diffraction of Tb 0.94Gd 0.06B 2C 2  

NASA Astrophysics Data System (ADS)

We performed powder neutron diffraction experiments of Tb 0.94Gd 0.06B 2C 2 with transition temperatures at TO=14.2 K and TN=20.6 K in order to examine the magnetic structure in phase IV ( T< TO) and phase AFM1 ( TO< T< TN). The experiments reveal that phase IV has an (1 0 {1}/{2})-type antiferromagnetic (AFM) structure where the magnetic moments are aligned antiferromagnetically along the tetragonal c-axis, while phase AFM1 has an (1 0 0)-type AFM structure where the magnetic moments are aligned ferromagnetically along the c-axis. These results support our previous proposition that TO is an antiferro-octupolar (AFO) transition temperature.

Sasaki, Y.; Mastuoka, E.; Ohoyama, K.; Onodera, H.

2009-10-01

87

Crystal growth and optical properties of lithium-lanthanide oxides: Li LnO 2 ( Ln = Nd, Sm, Eu, Gd and Dy)  

NASA Astrophysics Data System (ADS)

Single crystals of Li LnO 2 ( Ln = Nd, Sm, Eu, Gd, Dy) were grown out of a high temperature hydroxide melt. The crystal structures were determined by single crystal X-ray diffraction. These oxides crystallize in the space groups P2 1/ c (Nd, Sm - ?-type) and Pnma (Eu, Gd, Dy - ?-type) as a function of the lanthanide cation size. The structure of the ?-type (Nd, Sm) contains lithium in approximately trigonal bipyramidal coordination environments that connect to form rings around two lanthanide atoms, where the rings interconnect to form zig-zag layers. The structure of the ?-type (Eu, Gd, Dy) contains lithium in a distorted tetrahedral coordination environment, where two edges are shared to generate infinite chains separated by the rare earth cation. LiGdO 2 and LiEuO 2 luminesce in the visible range with emission maxima at 610 and 609 nm respectively.

Cantwell, Jacqueline R.; Roof, Irina P.; Smith, Mark D.; Loye, Hans-Conrad zur

2011-05-01

88

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

SciTech Connect

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

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

2012-09-15

89

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

PubMed

Sol-gel method was applied to prepare homogenous and highly crystalline phosphors with the formulas ?-GdB5O9:xTb(3+) (0 ? x ? 1), ?-Gd1-xCexB5O9 (0 ? x ? 0.40), ?-GdB5O9:xCe(3+), 0.30Tb(3+) (0 ? x ? 0.15) and ?-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 ?-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 ?-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 ?-GdB5O9:xEu(3+) in the literature indicate that ?-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

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

2015-01-20

90

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

91

Luminescence, energy transfer and color perception studies of Na3Gd(PO4)2:Dy3+:Tm3+ phosphors  

NASA Astrophysics Data System (ADS)

The white-light-emitting Na3Gd(PO4)2:Dy3+:Tm3+ phosphors were prepared by high temperature solid-state reaction technique. X-ray diffraction, luminescence excitation, emission, and decay measurements were performed. Upon Gd3+8S7/2 ? 6IJ (275 nm) excitation, the phosphors emit intense blue and yellow luminescence originating from the Dy3+4F9/2 ? 6H15/2 and Dy3+4F9/2 ? 6H13/2 transitions together with the Gd3+6P7/2 ? 8S7/2 transition at 313 nm. The excitation of Tm3+ ions by 352 nm radiation results also in efficient yellow and blue luminescence. The luminescence enhancement of Dy3+ in the presence of Tm3+ is discussed. The energy transfer process of the Tm3+-Dy3+ system is also explored. This study includes the color perception analysis of synthesized phosphors. The pure white-light is observed with Na3Gd(PO4)2:1%Dy3+:1%Tm3+ and is a promising material for white-lighting applications.

Jamalaiah, B. C.; Jo, Misun; Zehan, Jiang; Shim, Jae Jeong; Kim, Sun Il; Chung, Wan-Young; Seo, Hyo Jin

2014-08-01

92

Magnetic properties of quadruple perovskites BaLnRuO (Ln=La, Nd, Sm-Gd, Dy-Lu)  

Microsoft Academic Search

Quadruple perovskites BaLnRuO (Ln=La, Nd, Sm-Gd, Dy-Lu) were prepared and their magnetic properties were investigated. They adopt the 12L-perovskite-type structure consisting of RuO trimers and LnO octahedra. All of these compounds show an antiferromagnetic transition at 2.5-30 K. For BaNdRuO, ferrimagnetic ordering has been observed at 11.5 K. The observed magnetic transition is due to the magnetic behavior of the

Yuki Shimoda; Yoshihiro Doi; Makoto Wakeshima; Yukio Hinatsu

2010-01-01

93

Magnetic properties of R 3Co 29Si 4B 10 (R=La, Ce, Pr, Nd, Sm, Gd and Dy) borides  

NASA Astrophysics Data System (ADS)

The crystal structure and magnetic properties of quaternary rare-earth intermetallic borides R3Co29Si4B10 with R=La, Ce, Pr, Nd, Sm, Gd and Dy have been studied by X-ray powder diffraction and magnetization measurements. All compounds crystallize in a tetragonal crystal structure with the space group P4/nmm. Compounds with R=La, Ce, Pr, Nd and Sm are ferromagnets, while ferrimagnetic behavior is observed for R=Gd and Dy. The Curie temperatures vary between 149 K and 210 K. The Curie temperatures in R3Co29Si4B10 (R=Ce, Pr, Nd, Sm, Gd, Dy) compounds are roughly proportional to the de Gennes factors.

zdemir, Ay?e; Dubenko, Igor; Samanta, Tapas; Ali, Naushad; Gl, Fatma; Kervan, Seluk; Kervan, Nazmiye

2012-03-01

94

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

PubMed

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

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

2014-06-01

95

Magnetic ordering in Dy(BrO 3) 39H 2O and Tb(BrO 3) 39H 2O  

NASA Astrophysics Data System (ADS)

Dipolar ferromagnetic ordering in two pseudo-hexagonal rare earth bromates (RBR) has been investigated calorimetrically above 0.09 K. In DyBR a ?-anomaly has been observed in Cp at Tc = 0.161 K. Ordering in non-Kramers TbBR at 0.125 K is that of an electron-nucleus system in the mixed regime.

Simizu, Satoru; Bellesis, G. H.; Friedberg, S. A.

1986-02-01

96

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

SciTech Connect

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.

Feng Zai [Department of Material Science and Engineering, Sichuan Univiersity, Chengdu, 610064 (China)], E-mail: fz827@163.om; Wu Wei; Zhao Hui [Department of Material Science and Engineering, Xihua Univiersity, Chengdu, 610039 (China); Yin Guangfu [Department of Material Science and Engineering, Sichuan Univiersity, Chengdu, 610064 (China)

2009-04-15

97

Electron Density Study of Garnets: Z3Ga 5O 12; Z=Nd, Sm, Gd, Tb  

NASA Astrophysics Data System (ADS)

The electron density distribution in garnets, Z3Ga 5O 12, Z=Nd, Sm, Gd, Tb, has been studied with single-crystal X-ray diffraction methods through scattering factor refinement procedures. The Zsite shows a variety of electron density residual distribution modes, implying contribution of the felectrons. Residual electron density regions of 0.9-4.0 e/ 3height seen for all four garnets at an interstitial site (Wyckoff position 48 g) suggest coexistence of domains with alternatively oriented structural motifs within the single crystals. [Cubic Iaoverline3d; a=12.5051(4) ( Z=Nd), a=12.4361(3) ( Z=Sm), a=12.3829 (5) ( Z=Gd), a=12.3474(5) ( Z=Tb), final Rafter anharmonic refinement: Z=Nd, 0.0114 (for 660 equivalent-averaged data); Z=Sm, 0.0111 (647); Z=Gd, 0.0152 (428); Z=Tb, 0.0118 (454).

Sawada, Haruo

1997-09-01

98

KCa4(BO3)3:Ln3+ (Ln = Dy, Eu, Tb) phosphors for near UV excited white-light-emitting diodes  

NASA Astrophysics Data System (ADS)

A series of doped KCa4(BO3)3:Ln3+ (Ln: Dy, Eu and Tb) compositions were synthesized by solid-state reaction method and their photoluminescent properties were systematically investigated to ascertain their suitability for application in white light emitting diodes. The X-ray diffraction (XRD) and nuclear magnetic resonance (MAS-NMR) data indicates that Ln3+-ions are successfully occupied the non-centrosymmetric Ca2+ sites, in the orthorhombic crystalline phase of KCa4(BO3)3 having space group Ama2, without affecting the boron chemical environment. The present phosphor systems could be efficiently excitable at the broad UV wavelength region, from 250 to 350 nm, compatible to the most commonly available UV light-emitting diode (LED) chips. Photoluminescence studies revealed optimal near white-light emission for KCa4(BO3)3 with 5 wt.% Dy3+ doping, while warm white-light (CIE; X = 0.353, Y = 0.369) is obtained at 1wt.% Dy3+ ion concentration. The principle of energy transfer between Eu3+ and Tb3+ also demonstrates the potential white-light from KCa4(BO3)3:Eu3+,Tb3+ phosphor. Whereas, single Tb3+ and Eu3+-doped systems showed bright green (Tb3+) and red (Eu3+) emissions, respectively. Having structural flexibility along with remarkable chemical/thermal stability and suitable quantum efficiency these phosphors can be promising candidates as white-light-emitter for near UV LEDs.

Reddy, Allu Amarnath; Das, Subrata; Goel, Ashutosh; Sen, Rupam; Siegel, Rene; Mafra, Lus; Prakash, G. Vijaya; Ferreira, Jos M. F.

2013-02-01

99

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

NASA Astrophysics Data System (ADS)

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

Landnez Tllez, D. A.; Martnez Buitrago, D.; Cardona C, R.; Barrera, E. W.; Roa-Rojas, J.

2014-06-01

100

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

PubMed

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

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

2015-01-28

101

Effect of polyvinyl alcohol on rare earths (Gd and Tb) separation by extraction resin.  

PubMed

Small amounts of polyvinyl alcohol (PVA; 0.5-1.5 wt.%) added to extraction resin was synthesized by suspension polymerization. Their effects on the separation of rare earths (RE) were then investigated by conducting a relative comparison with the performance of pure extraction resin. The supporter and extractant of extraction resin were styrene-divinyl benzene copolymer and 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (HEH[EHP]), respectively. The size of PVA added extraction resin was reduced by 40% particle size of pure extraction resin. Furthermore, a higher level of PVA addition, shorter effluent range and smaller resolution values were shown in the extraction. In constant PVA added extraction resin, more diluted effluent concentration, longer effluent range and bigger resolution values were shown in the extraction. This could be the result of the bonding force between the rare earths and the extraction resin due to the nature of the interaction between the OH(-) group in PVA and the OH(-) group in extractants such as HEH[EHP]. Thus, the bonding force between the RE and extractants was determined by the level of PVA in the resins and the acidity of the effluent solution became another important factor in the extraction performance of the rare earths. As a result, the optimal level of PVA addition and the concentration of effluent for RE (Gd and Tb) separation were determined to be 0.5 wt.% of PVA and 0.05 M HCl of effluent, respectively. PMID:18970417

Kim, Joon-Seok; Han, Choon; Wee, Jung-Ho; Kim, Joon-Soo

2006-01-15

102

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)

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.

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

2014-05-01

103

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

PubMed

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

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

2010-05-14

104

Phase transitions of LnAs (Ln = Pr, Nd, Sm, Gd, Dy and Ho) with NaCl-type structure at high pressures  

NASA Astrophysics Data System (ADS)

By use of synchrotron radiation the powder x-ray diffraction of lanthanide monoarsenides LnAs (Ln = Pr, Nd, Sm, Gd, Dy and Ho) with a NaCl-type structure has been studied up to 60 GPa at room temperature. First-order phase transitions with crystallographic change were found at around 27.1 GPa for PrAs, 24.2 GPa for NdAs and 32.1 GPa for SmAs. The high-pressure form of the lighter LnAs (Ln = Pr, Nd and Sm) is a tetragonal structure and can be viewed as a distorted CsCl-type structure. The atoms in the tetragonal structure are located at Ln: 0,0,0; As: 1/2,1/2,1/2. The space group is P4/mmm. Pressure-induced phase transitions of the heavier LnAs (Ln = Gd, Dy and Ho) with many f electrons occur at around 36 GPa for GdAs, 44 GPa for DyAs and 46 GPa for HoAs. The structure of these high-pressure phases is unknown. The high-pressure structural behaviour of LnAs (Ln = Pr, Nd, Sm, Gd, Dy and Ho) with the NaCl-type structure is discussed.

Shirotani, Ichimin; Yamanashi, Keigo; Hayashi, Junichi; Tanaka, Yuu; Ishimatsu, Naoki; Shimomura, Osamu; Kikegawa, Takumi

2001-03-01

105

Sensitive element of the magnetic field sensor based on three-layer film system Co/ X/Co ( X = Dy, Gd)  

NASA Astrophysics Data System (ADS)

We report on the results of investigation of magnetoresistive properties of Co/Dy/Co and Co/Gd/Co film systems that can be used as the sensitive element of a magnetic field sensor. It is shown that various fields of application can be chosen depending on the magnetic characteristics.

Vorobiov, S. I.; Shutylieva, O. V.; Pazukha, I. M.; Chornous, A. M.

2014-11-01

106

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

107

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

SciTech Connect

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

Alexander S. Chernyshov

2006-08-09

108

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

NASA Astrophysics Data System (ADS)

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 . 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.

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

2014-03-01

109

Surfactant-assisted hydrothermal synthesis of octahedral structured NaGd(MoO4)2:Eu3+/Tb3+ and tunable photoluminescent properties  

NASA Astrophysics Data System (ADS)

NaGd(MoO4)2:Eu3+/Tb3+ phosphors were synthesized via a facile hydrothermal method with a surfactant-assisted environment. The properties were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and photoluminescence (PL). The XRD patterns and FESEM image indicate that NaGd(MoO4)2:Eu3+/Tb3+ phosphors crystallize well with the scheelite structure and the morphology of the sample is octahedral. The octahedral morphology of the phosphors is found to be manipulated by the glutamic acid. The luminescent properties reveal that under 277 nm excitation, Eu3+ and Tb3+ doped NaGd(MoO4)2 phosphors show strong red and green emission. Moreover, Eu3+ and Tb3+ co-doped NaGd(MoO4)2 phosphors display the multicolor luminescence when excited by a single excitation wavelength or different excitation wavelengths, and the luminescence colors of the samples can be tuned from red, yellow, yellow-green, to green when adjusting the doping concentration of the activator ions. Furthermore, the possible energy transfer mechanism in Tb3+ and Eu3+ co-doped NaGd(MoO4)2 was proposed in term of the experimental results and analysis. The as-prepared phosphors may find potential applications in the field such as color displays.

Jiang, Yingying; Liu, Yan; Liu, Guixia; Dong, Xiangting; Wang, Jinxian; Yu, Wensheng; Dong, Qun

2014-09-01

110

Flexible Gd2O2S:Tb scintillators pixelated with polyethylene microstructures for digital x-ray image sensors  

NASA Astrophysics Data System (ADS)

Flexible scintillators for digital x-ray image sensors were designed, fabricated and characterized. In these scintillaotrs, terbium-doped gadolinium oxysulfide (Gd2O2S:Tb) scintillator pixels were embedded into a polyethylene (PE) substrate. To evaluate the difference in the spatial resolution according to the pixel size, we designed three scintillators with pixels of different pitch sizes: 50 m pitch size (P50), 100 m pitch size (P100) and 200 m pitch size (P200). Because of the high flexibility and good formability, polyethylene was used as the substrate of the scintillator. To fabricate nickel micromolds with high-aspect-ratio microstructures, two microfabrication techniques were employed: silicon dry-etching using a deep reactive ion etching (DRIE) process and nickel electroforming. The pixelated PE microstructures were fabricated by a hot embossing process. Because the solution-type Gd2O2S:Tb precursor can be handled at room temperature, Gd2O2S:Tb was used as the scintillator material. The measured sensitivities of the P50 and P100 models were, respectively, about 65% and 97% of that of the P200 model. The lower sensitivity values of the models with a small pitch size were due to two factors, such as the different pixel heights and the different fill factors. Because a scintillator with a small pixel size has a low fill factor, the sensitivity of the scintillator decreases as the pixel size decreases. The fill factors of the P50, P100 and P200 models were 36%, 49% and 56.25%, respectively. On the other hand, the spatial resolution of the scintillator increases as the pixel size decreases. Therefore, P50 gave the best spatial resolution among the designed models. The spatial frequency at 10% of the modulation transfer function (MTF) with P50 was 13.5 mm-1, while that with P200 was 10.0 mm-1. The resolution pattern and the tooth x-ray images obtained from a scintillator with a smaller pixel size was also clearer than that obtained from a scintillator with a larger pixel size. PE-based flexible Gd2O2S:Tb scintillators can be utilized directly in flexible x-ray image sensors.

Jung, Im Deok; Cho, Min Kook; Lee, Sang Min; Bae, Kong Myeong; Jung, Phill Gu; Lee, Chi Hoon; Lee, Jae Min; Yun, Seungman; Kim, Ho Kyung; Kim, Seong Sik; Ko, Jong Soo

2009-01-01

111

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

Microsoft Academic Search

Rare-earth ions (Eu3+, Tb3+, Dy3+) doped SrMoO4 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

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

2011-01-01

112

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

NASA Astrophysics Data System (ADS)

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.

Khanna, A.; Dutta, P. S.

2013-02-01

113

A novel strong green phosphor: K3Gd(PO4)2:Ce3+, Tb3+ for a UV-excited white light-emitting-diode  

NASA Astrophysics Data System (ADS)

A series of K3Gd1-x-y(PO4)2:xCe3+, yTb3+ phosphors are synthesized by the solid-sate reaction method. X-ray diffraction and photoluminescence spectra are utilized to characterize the structures and luminescence properties of the as-synthesized phosphors. Co-doping of Ce3+ enhances the emission intensity of Tb3+ greatly through an efficient energy transfer process from Ce3+ to Tb3+. The energy transfer is confirmed by photoluminescence spectra and decay time curves analysis. The efficiency and mechanism of energy transfer are investigated carefully. Moreover, due to the non-concentration quenching property of K3Tb(PO4)2, the photoluminescence spectra of K3Tb1-x(PO4)2:xCe3+ are studied and the results show that when x = 0.11 the strongest Tb3+ green emission can be realized.

Jiang, Ting-Ming; Yu, Xue; Xu, Xu-Hui; Zhou, Da-Cheng; Yu, Hong-Ling; Yang, Peng-Hui; Qiu, Jian-Bei

2014-02-01

114

Structure and optical properties of Dy3+/Tm3+ co-doped oxyfluoride glass ceramics containing ?-NaGdF4 nanocrystals  

NASA Astrophysics Data System (ADS)

Dy3+/Tm3+ co-doped oxyfluoride glass ceramics containing hexagonal ?-NaGdF4 nanocrystals were prepared by the melt-quenching method and subsequent heat-treatment procedure. During the crystallization process, the structural evolution of glass network was systematically investigated using XRD, TEM and FTIR spectra. Experimental results provided new evidences that a silica-enriched layer around the precipitated fluoride nanocrystals was formed during the crystallization process. Strong white light emission was obtained in the oxyfluoride glass ceramics by modifying the relative concentration ratio of Tm3+ and Dy3+ ions.

Sun, Xiao; Zhao, Shilong; Fei, Yong; Huang, Lihui; Xu, Shiqing

2014-12-01

115

Bifunctional Gd(III) and Tb(III) chelates based on a pyridine-bis(iminodiacetate) platform, suitable optical probes and contrast agents for magnetic resonance imaging.  

PubMed

To study the physicochemical properties of lanthanide complexes derived from a bifunctional chelating agent based on a PMN-tetraacetic acid moiety {PMN-tetraacetic acid (1): [2,6-pyridinediylbis(methylene nitrilo)-tetraacetic acid]}, 4-carboxylic acid substituted pyridine derivative (2) was synthesized. This ligand forms heptadentate (N3 O4 ) Ln(III) complexes (Ln = Gd, Eu, Tb), with two water molecules completing the inner coordination sphere of the metal. The parameters that govern the relaxivity of the Gd(III) complex and the luminescence of Eu(III) and Tb(III) complexes were obtained by (17) O and (1) H NMR studies and time-resolved fluorescence experiments, respectively. The gadolinium and terbium complexes show interesting properties either for MRI or FOR optical imaging; that is, for the Gd complex, a high proton relaxivity (r1 ?= 6.4 s(-1) mM(-1) at 20 MHz) with short water residence time (?M ?= 38.5 ns); for the Tb complex, a luminescence lifetime of 1.22 ms at room temperature and a luminescence quantum yield of 10%. The kinetic stability of these complexes toward blood protein, cation or bioactive oxyanion was also examined. The Gd(2)(H2O)2 complex does not interact with human serum albumin, but undergoes a transmetalation reaction with Zn(II) in a phosphate buffer solution (pH?7.4), rather similar to that of Gd-DTPA-BMA(H2 O). On the other hand, as observed for Eu and Tb complexes, these chelates do not form ternary complexes with bidentate anions such as l-lactate, citrate or carbonate. Finally, a phosphatidylserine-specific hexapeptide (TLVSSL) was grafted on Gd or Tb chelates, and the Gd-peptide conjugate was used in vitro for targeting apoptotic cells. PMID:24706614

Laurent, Sophie; Vander Elst, Luce; Galaup, Chantal; Leygue, Nadine; Boutry, Sbastien; Picard, Claude; Muller, Robert N

2014-01-01

116

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

117

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

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}

Hartenbach, Ingo [Institute for Inorganic Chemistry, University of Stuttgart, D-70569 Stuttgart (Germany)]. E-mail: hartenbach@iac.uni-stuttgart.de; Jagiella, Stefan [Institute for Physical Chemistry, University of Stuttgart, D-70569 Stuttgart (Germany); Schleid, Thomas [Institute for Inorganic Chemistry, University of Stuttgart, D-70569 Stuttgart (Germany)]. E-mail: schleid@iac.uni-stuttgart.de

2006-08-15

118

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

SciTech Connect

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

Khanna, A. [Smart Lighting Engineering Research Center, 110, 8th Street, Troy, New York, 12180 (United States) [Smart Lighting Engineering Research Center, 110, 8th Street, Troy, New York, 12180 (United States); Electrical, Computer and Systems Engineering Department, Rensselaer Polytechnic Institute, 110, 8th Street, Troy, New York, 12180 (United States); Dutta, P.S., E-mail: duttap@rpi.edu [Smart Lighting Engineering Research Center, 110, 8th Street, Troy, New York, 12180 (United States); Electrical, Computer and Systems Engineering Department, Rensselaer Polytechnic Institute, 110, 8th Street, Troy, New York, 12180 (United States)

2013-02-15

119

FT-Raman and FT-IR vibrational spectroscopic studies of nanocrystalline Ba 2RESbO 6 (RE = Sm, Gd, Dy and Y) perovskites  

Microsoft Academic Search

The nanoparticles of Ba2RESbO6 (RE=Sm, Gd, Dy and Y) were synthesized using auto ignition combustion process. The structure and phase purity of the as-prepared nanopowders were examined by X-ray diffraction pattern. A systematic analysis of the structure of the four compounds was carried out for the first time by recording Raman and IR spectra. The four Raman active modes A1g,

C. Vijayakumar; H. Padma Kumar; Sam Solomon; J. K. Thomas; P. R. S. Wariar; Annamma John

2009-01-01

120

Crystallographic and magnetic phase transitions in the layered ruthenium oxy-arsenides TbRuAsO and DyRuAsO  

SciTech Connect

The crystallographic and physical properties of TbRuAsO and DyRuAsO at and below room temperature are reported, including full structure refinements from powder X-ray diffraction data and measured electrical and thermal transport properties, magnetic susceptibility, and heat capacity. Both compounds are isostructural to LaFeAsO (ZrCuSiAs-type, P4/nmm) at room temperature. However, DyRuAsO undergoes a symmetry-lowering crystallographic phase transition near 25 K, and adopts an orthorhombic structure (Pmmn) below this temperature. This structural distortion is unlike those observed in the analogous Fe compounds. Magnetic phase transitions are observed in both compounds which suggest antiferromagnetic ordering of lanthanide moments occurs near 7.0 K in TbRuAsO and 10.5 K in DyRuAsO. The nature of the structural distortion as well as thermal conductivity and heat capacity behaviors indicate strong coupling between the magnetism and the lattice. The behaviors of both materials show magnetic ordering of small moments on Ru may occur at low temperatures.

McGuire, Michael A [ORNL; May, Andrew F [ORNL; Sales, Brian C [ORNL

2012-01-01

121

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

SciTech Connect

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.

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

2013-06-15

122

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

SciTech Connect

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 (TGDTA), 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.

Song, Hejuan, E-mail: songhejuan0708@163.com; Zhou, Liqun, E-mail: zlq@hubu.edu.cn; Li, Ling; Hong, Fei; Luo, Xinru

2013-12-15

123

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

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

Asiri Naidu, S. [Laboratoire CRISMAT (CNRS UMR6508), ENSICAEN, Universite de Caen, 6 Bd Marechal Juin, 14050 Caen Cedex (France); Boudin, S., E-mail: sophie.boudin@ensicaen.fr [Laboratoire CRISMAT (CNRS UMR6508), ENSICAEN, Universite de Caen, 6 Bd Marechal Juin, 14050 Caen Cedex (France); Varadaraju, U.V. [Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036 (India); Raveau, B. [Laboratoire CRISMAT (CNRS UMR6508), ENSICAEN, Universite de Caen, 6 Bd Marechal Juin, 14050 Caen Cedex (France)

2012-06-15

124

Synthesis, structure, and magnetic characterization of La2-xRxRuO5 (R = Pr, Nd, Sm, Gd, Dy)  

NASA Astrophysics Data System (ADS)

Polycrystalline samples of La2-xRxRuO5 (R = Pr, Nd, Sm, Gd, Dy) have been prepared, applying a soft-chemistry route based on the thermal decomposition of citric acid precursors. By powder x-ray and neutron diffraction the crystal structures have been investigated in detail. For the unsubstituted parent compound La2RuO5, synchrotron x-ray diffraction patterns reveal a broad structural phase transition regime around 170 K without any significant hysteresis. This structural transition is linked with a drastic reduction of the magnetic susceptibility. A similar behavior was also observed for the lanthanide-substituted compounds La2-xRxRuO5. Magnetic measurements reveal the coexistence of two weakly interacting magnetic sublattices. The effect of rare-earth substitution on the magnetic phase transition is resulting from structural modifications caused by the smaller radius of the R3+ ions. These ions are predominantly located within the LaO-layers, which are alternating with LaRuO4 layers. The transition temperatures determined by differential scanning calorimetry (DSC) are compared to data derived from the susceptibility measurements.

Riegg, S.; Sazama, U.; Frba, M.; Reller, A.; Ebbinghaus, S. G.

2011-07-01

125

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

SciTech Connect

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.

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

2010-01-15

126

Optical and magneto-optical characterization of TbFeCo and GdFeCo thin films for high-density recording  

NASA Astrophysics Data System (ADS)

Thin, optically semi-infinite films of amorphous TbFeCo and GdFeCo, suitable for magneto-optical recording, have been deposited by DC magnetron sputtering onto glass. Ellipsometric techniques have been used to determine the complex refractive index and complex magneto-optical parameter of the films in the wavelength range 400-900 nm, thus characterizing the materials. A review of the literature is presented and shows that the results for the TbFeCo films compare favourably with published results obtained from measurements conducted in situ, with the films protected with ZnS barrier layers. It is found that GdFeCo and TbFeCo are optically very similar, but magneto-optically the materials are quite different.

Hendren, W. R.; Atkinson, R.; Pollard, R. J.; Salter, I. W.; Wright, C. D.; Clegg, W. W.; Jenkins, D. F. L.

2003-03-01

127

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

SciTech Connect

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

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

2009-09-15

128

Crystal growth, transport, and the structural and magnetic properties of Ln(4)FeGa(12) with Ln = Y, Tb, Dy, Ho, and Er.  

PubMed

Ln(4)FeGa(12), where Ln is Y, Tb, Dy, Ho, and Er, prepared by flux growth, crystallize with the cubic Y(4)PdGa(12) structure with the Im3m space group and with a = 8.5650(4), 8.5610(4), 8.5350(3), 8.5080(3), and 8.4760(3) A, respectively. The crystal structure consists of an iron-gallium octahedra and face-sharing rare-earth cuboctahedra of the Au(3)Cu type. Er(4)Fe(0.67)Ga(12) is iron-deficient, leading to a distortion of the octahedral and cuboctahedral environments due to the splitting of the Ga2 site into Ga2 and Ga3 sites. Further, interstitial octahedral sites that are unoccupied in Ln(4)FeGa(12) (Ln = Y, Tb, Dy, and Ho) are partially occupied by Fe2. Y(4)FeGa(12) exhibits weak itinerant ferromagnetism below 36 K. In contrast, Tb(4)FeGa(12), Dy(4)FeGa(12), Ho(4)FeGa(12), and Er(4)Fe(0.67)Ga(12) order antiferromagnetically with maxima in the molar magnetic susceptibilities at 26, 18.5, 9, and 6 K. All of the compounds exhibit metallic electric resistivity, and their iron-57 Mossbauer spectra, obtained between 4.2 and 295 K, exhibit a single-line absorption with a 4.2 K isomer shift of ca. 0.50 mm/s, a shift that is characteristic of iron in an iron-gallium intermetallic compound. A small but significant broadening in the spectral absorption line width is observed for Y(4)FeGa(12) below 40 K and results from the small hyperfine field arising from its spin-polarized itinerant electrons. PMID:20020728

Drake, Brenton L; Grandjean, Fernande; Kangas, Michael J; Okudzeto, Edem K; Karki, Amar B; Sougrati, Moulay T; Young, David P; Long, Gary J; Chan, Julia Y

2010-01-18

129

Huge magnetostriction in tb 3Fe 5O 12, dy 3Fe 5O 12, ho 3Fe 5O 12, er 3Fe 5O 12 garnets  

NASA Astrophysics Data System (ADS)

Giant magnetostriction was observed in some ferromagnetic garnets: TbIG, DyIG, HoIG at low temperature. The ? 111 magnetostrictive coefficients (deduced from the distortion of the lattice from cubic symmetry Ia 3d at 300 K toward rhombohedral symmetry R overline3c at low temperature) reach respectively, +240010 -6, -875100 -6 and -45010 -6 at 4.2 K. Magnetostriction and canted magnetic structure appear simultaneously and progressively at low temperature. The contribution to magnetostriction of the various anisotropic parameters (RE-iron exchange, crystal field acting on RE, spin-orbit coupling) are analysed.

Sayetat, F.

1986-04-01

130

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

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.

Velazquez, J. J.; Rodriguez, V. D.; Mendez-Ramos, J. [Departamento de Fisica Fundamental y Experimental, Electronica y Sistemas, Univ. La Laguna, La Laguna, 38206 Tenerife (Spain); Yanes, A. C.; Castillo, J. del [Departamento de Fisica Basica, Univ. La Laguna, La Laguna, 38206 Tenerife (Spain)

2010-12-01

131

Field-Induced Magnetic Properties in RCrO 4 Oxides ( R=Pr, Gd, Tb, Tm, and Yb)  

NASA Astrophysics Data System (ADS)

RCrO4 oxides (R=Pr, Gd, Tb, Tm, and Yb) have been synthesized at 773 K using the corresponding nitrates as precursors. X-ray diffraction data reveal that these samples are single phases and crystallize with the zircon-type structure, showing tetragonal symmetry, space group I41/amd. All the compounds are antiferromagnetic and the Nel temperature, which depends on the R3+ ion, takes values lower than 30 K. The presence of a canting appears to be responsible for the negative values of the magnetic susceptibility found below the compensation temperature. This uncommon phenomenon is named reversal of magnetization. It is field-dependent, being suppressed at 500 Oe for the TmCrO4 compound. The highest value of the compensation temperature (24 K) corresponds to the YbCrO4 oxide. A metamagnetic transition has been observed in all cases at critical fields ranging from 225 Oe (GdCrO4) to 1600 Oe (YbCrO4).

Jimnez, E.; Isasi, J.; Sez-Puche, R.

2002-03-01

132

Exchange interactions at the origin of slow relaxation of the magnetization in {TbCu?} and {DyCu?} single-molecule magnets.  

PubMed

New {TbCu3} and {DyCu3} single-molecule magnets (SMMs) containing a low-symmetry Ln(III) center (shape measurements relative to a trigonal dodecahedron and biaugmented trigonal prism are 2.2-2.3) surrounded by three Cu(II) metalloligands are reported. SMM behavior is confirmed by frequency-dependent out-of-phase ac susceptibility signals and single-crystal temperature and sweep rate dependent hysteresis loops. The ferromagnetic exchange interactions between the central Ln(III) ion and the three Cu(II) ions could be accurately measured by inelastic neutron scattering (INS) spectroscopy and modeled effectively. The excitations observed by INS correspond to flipping of Cu(II) spins and appear at energies similar to the thermodynamic barrier for relaxation of the magnetization, ~15-20 K, and are thus at the origin of the SMM behavior. The magnetic quantum number M(tot) of the cluster ground state of {DyCu3} is an integer, whereas it is a half-integer for {TbCu3}, which explains their vastly different quantum tunneling of the magnetization behavior despite similar energy barriers. PMID:25101774

Kettles, Fraser J; Milway, Victoria A; Tuna, Floriana; Valiente, Rafael; Thomas, Lynne H; Wernsdorfer, Wolfgang; Ochsenbein, Stefan T; Murrie, Mark

2014-09-01

133

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

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

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

2013-01-01

134

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

NASA Astrophysics Data System (ADS)

The ternary tellurides RECuTe2 (RE=Gd, Dy and Er) have been synthesized, their crystal structure and charge transport properties have been investigated. The tellurides adopt a monoclinicly distorted variant (C2/m, z=2) of the trigonal structure (P3barm1, Z=1) observed for RECuSe2 with RE=Dy, Er. The charge transport properties of RECuSe2 with RE=Pr and Sm have been also explored. While RECuTe2 display a metallic type resistivity, RECuSe2 show semiconducting properties. The room-temperature resistivities are between 0.22 and 10.5?cm, with larger values observed for the selenides. Electronic structure calculations support metallic and semiconducting conductivities for the tellurides and selenides, respectively. The Seebeck coefficient indicates that the dominant charge carries are holes for all phases.

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

2014-10-01

135

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

136

Magnetic properties of quadruple perovskites Ba4LnRu3O12 (Ln=La, Nd, Sm-Gd, Dy-Lu)  

Microsoft Academic Search

Quadruple perovskites Ba4LnRu3O12 (Ln=La, Nd, Sm-Gd, Dy-Lu) were prepared and their magnetic properties were investigated. They adopt the 12L-perovskite-type structure consisting of Ru3O12 trimers and LnO6 octahedra. All of these compounds show an antiferromagnetic transition at 2.5-30 K. For Ba4NdRu3O12, ferrimagnetic ordering has been observed at 11.5 K. The observed magnetic transition is due to the magnetic behavior of the

Yuki Shimoda; Yoshihiro Doi; Makoto Wakeshima; Yukio Hinatsu

2010-01-01

137

Magnetic properties of quadruple perovskites Ba 4 LnRu 3O 12 ( Ln=La, Nd, SmGd, DyLu)  

Microsoft Academic Search

Quadruple perovskites Ba4LnRu3O12 (Ln=La, Nd, SmGd, DyLu) were prepared and their magnetic properties were investigated. They adopt the 12L-perovskite-type structure consisting of Ru3O12 trimers and LnO6 octahedra. All of these compounds show an antiferromagnetic transition at 2.530K. For Ba4NdRu3O12, ferrimagnetic ordering has been observed at 11.5K. The observed magnetic transition is due to the magnetic behavior of the Ru4.33+3O12 trimer

Yuki Shimoda; Yoshihiro Doi; Makoto Wakeshima; Yukio Hinatsu

2010-01-01

138

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

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.

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

2012-01-15

139

Coherent precipitation in the TbCu7-type GdCo-based ribbons prepared by simple processing  

NASA Astrophysics Data System (ADS)

Isotropic Gd(Co0.88-xCuxFe0.09Zr0.03)7 (x =0.10-0.20) ribbons with TbCu7 structure have been prepared by melt-spinning technique. A uniform and fine cellular microstructure consisting of 2:17 cell with 1:5 cell-boundary phase is developed by simply slow cooling the ribbons from 850 to 400C without the standard solid solution and isothermal aging treatments. It is interesting to note that the original grain boundary of 1:7 phase still exists in the precipitation-hardened ribbons and the crystallographic texture is formed in each 1:7 granular region after the treatment. This gives a way to fabricate the textured magnets with nanostructure. Positive temperature coefficients of remanence and coercivity are observed in the ribbons. The coercivity mechanism of the precipitation-hardened ribbons is discussed at the temperature ranging from room temperature to 600C. It is proposed that the residual 1:7 phase boundaries act as effective pinning sites at high temperatures.

Rong, Chuan-Bing; Zhang, Hong-Wei; Zhang, Jian; Du, Xiao-Bo; Zhang, Shao-Ying; Shen, Bao-Gen

2005-02-01

140

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)

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 ?m. 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).

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

2015-02-01

141

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

A series of heterometallic [Ln(III)(x)Cu(II)(y)] complexes, [Gd2Cu2]n (1), [Gd4Cu8] (2), [Ln9Cu8] (Ln=Gd, 3Gd; Ln=Dy, 3Dy), 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

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

2013-12-16

142

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

SciTech Connect

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.

Karunadasa, H.; Regan, K.A.; Cava, R.J. [Department of Chemistry, Princeton University, Princeton, New Jersey 08544 (United States); Huang, Q.; Lynn, J.W. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Ueland, B.G.; Schiffer, P. [Department of Physics and Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

2005-04-01

143

Magnetostriction in (Tb0.45Dy0.55)1-xErxCo2 (x = 0.1, 0.2): high-field investigation  

NASA Astrophysics Data System (ADS)

Intermetallic compounds (Tb0.45Dy0.55)1-xErxCo2 (x = 0.1; 0.2) were synthesized using high purity rare-earth metals. Multicomponent compositions with compensated magnetic anisotropy (MA) were chosen with respect to theoretical predictions based upon the single-ion MA model. Magnetostriction was measured in magnetic fields up to 10 T within the temperature range of 1.5-200 K by means of strain gauges. In the vicinity of magnetic phase transitions (160-170 K), giant volume magnetostriction (~210-3 in 10 T) provided by the band magnetism of a Co sublattice was observed in the compounds studied.

Tereshina, I.; Politova, G.; Tereshina, E.; Cwik, J.; Nikitin, S.; Chistyakov, O.; Karpenkov, A.; Karpenkov, D.; Palewski, T.

2011-07-01

144

Spin-Lattice Coupling in Ferroelectric Spiral Magnets: Comparison between the Cases of (Tb,Dy)MnO3 and CoCr2O4  

NASA Astrophysics Data System (ADS)

Lattice modulation expected for various types of spiral magnetic ordering with a propagation vector Qm is discussed in terms of the symmetric (Si\\cdotSj type) and antisymmetric (SiSj type) exchange interactions between neighboring spins (Si and Sj). We show that the conical ordering causes the superlattice modulation with Qm via the antisymetric interaction, while the elliptical deformation of spiral induces a 2Qm modulation in lattice, due to the symmetric and antisymmetric interactions. This theoretical prediction was experimentally confirmed for a transverse elliptical antiferromagnet (Tb,Dy)MnO3 and a transverse conical ferrimagnet CoCr2O4, both accompanied by ferroelectricity (lattice deformation with Q=0) as well.

Arima, Taka-hisa; Yamasaki, Yuichi; Goto, Takeshi; Iguchi, Satoshi; Ohgushi, Kenya; Miyasaka, Shigeki; Tokura, Yoshinori

2007-02-01

145

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

146

The generalized planar fault energy, ductility, and twinnability of Al and AlRE (RE = Sc, Y, Dy, Tb, Nd) at different temperatures: A first-principles study  

NASA Astrophysics Data System (ADS)

The genearlized planar fault energies of Al and AlRE (RE = Sc, Y, Dy, Tb, Nd) alloys have been investigated using first-principles methods combined with a quasiharmonic approach. The stacking fault energies, unstable stacking fault energies, and unstable twinning energies decrease slightly with increasing temperature. The ductility parameter D, the relative barrier difference ?utus, and the twinnability ?a of Al and AlRE alloys at different temperatures have been determined. It is found that the ductilities of Al and Al alloys are nearly the same and the ductilities increase slightly with increasing temperature. The RE alloying elements make twinning more likely and the twinnabilities of Al and Al alloys decrease with increasing temperature.

Wu, Xiao-Zhi; Liu, Li-Li; Wang, Rui; Liu, Qing

2014-06-01

147

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

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.

Niu, Na [College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)] [College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Yang, Piaoping, E-mail: piaoping@ciac.jl.cn [College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)] [College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Wang, Wenxin; He, Fei; Gai, Shili; Wang, Dong [College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)] [College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Lin, Jun, E-mail: jlin@ciac.jl.cn [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)] [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

2011-03-15

148

Tunable white-light emission from mixed lanthanide (Eu?, Gd?, Tb?) coordination polymers derived from 4-(dipyridin-2-yl)aminobenzoate.  

PubMed

Herein, we have developed a series of isostructural mixed Ln(3+)-4-(dipyridin-2-yl)aminobenzoate coordination polymers [Ln(3+) = Eu(3+) (1), Tb(3+) (2), and Gd(3+) (3)], and characterized and investigated their photophysical properties. The results demonstrated that by gently tuning the excitation wavelength of these mixed lanthanide complexes, white light emission can be realized with the Commission Internationale de I'Eclairage coordinates (0.32, 0.34). Furthermore, by changing the concentration profiles of lanthanide ions stoichiometrically in mixed-lanthanide complexes and exciting at particular wavelengths, various emission colours can also be successfully obtained. The antenna ligand, 4-(dipyridin-2-yl)aminobenzoic acid, provides an efficient energy transfer for the sensitization of Eu(3+) and Tb(3+) complexes and exhibits red and green emissions, respectively. Most importantly, due to the high energy (32,150 cm(-1)) of the Gd(3+) ion lowest-lying emission level, the corresponding Gd(3+) complex displays ligand-centered visible emission in the blue light region, and hence it acts as a blue emitter. Therefore, Eu(3+) and Tb(3+) complexes in conjunction with a Gd(3+) complex is a suitable choice to obtain tunable white-light-emission from Ln(3+) coordination polymers. The morphological analyses of the mixed lanthanide coordination polymers by transmission electron microscopy (TEM) disclose that these compounds exist as unique crystalline nano-rods with an average diameter of 200 nm. The developed mixed lanthanide complexes also exhibit high thermal stability (~420 C). PMID:24903008

Ramya, A R; Varughese, Sunil; Reddy, M L P

2014-07-28

149

Ba2LnSbO6 and Sr2LnSbO6 (Ln = Dy, Ho, Gd) double perovskites: Lanthanides in the geometrically frustrating fcc lattice  

PubMed Central

Magnetic ground states in solids often arise as a result of a delicate balance between competing factors. One currently active area of research in magnetic materials involves compounds in which long-range magnetic ordering at low temperatures is frustrated by the geometry of the crystalline lattice, a situation known as geometrical magnetic frustration. The number of systems known to display the effects of such frustration is growing, but those that are sufficiently simple from theoretical, chemical, and physical perspectives to allow for detailed understanding remain very few. A search for model compounds in this family has led us to the double perovskites Ba2LnSbO6 and Sr2LnSbO6 (Ln = Dy, Ho, and Gd) reported here. Ba2DySbO6,Ba2HoSbO6,Sr2DySbO6, and Sr2HoSbO6 are structurally characterized by powder neutron diffraction at ambient temperature. The trivalent lanthanides and pentavalent antimony are found to be fully ordered in the double-perovskite arrangement of alternating octahedra sharing corner oxygens. In such a structure, the lanthanide sublattice displays a classical fcc arrangement, an edge-shared network of tetrahedra known to result in geometric magnetic frustration. No magnetic ordering is observed in any of these compounds down to temperatures of 2 K, and in the case of the Dy-based compounds in particular, frustration of the magnetic ordering is clearly present. Lanthanide-based double perovskites are proposed to be excellent model systems for the detailed study of geometric magnetic frustration. PMID:12824460

Karunadasa, H.; Huang, Q.; Ueland, B. G.; Schiffer, P.; Cava, R. J.

2003-01-01

150

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

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}.

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

2007-04-15

151

Effect of magnetism and average radius at A-site on TCTC in Nd0.6Ln0.1Sr0.3MnO3 (Ln=La, Pr, Gd, Dy) system  

NASA Astrophysics Data System (ADS)

The magnetic properties of Nd 0.6Ln 0.1Sr 0.3MnO 3 compositions (Ln = La, Pr, Gd, Dy) have been investigated thoroughly. The effect of is considered to be profound on the PM-FM phase transition in the manganites. The experiment results indicate that TC decreases with Ln changing from La to Gd due to the decreases of . The abnormal increase of TC in Dy-composition with the smallest and largest ?2 is attributed to the large magnetic moment of Dy 3+ ions. The rapid increase of magnetization below 30 K indicates directly the magnetic ordering of rare earth ions at A-site.

Ling, Langsheng; Fan, Jiyu; Pi, Li; Tan, Shun; Zhang, Yuheng

2008-01-01

152

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

SciTech Connect

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.

Riedemann, T.M.

1996-05-01

153

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

NASA Astrophysics Data System (ADS)

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

Morrison, Gregory; zur Loye, Hans-Conrad

2015-01-01

154

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)

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.

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

155

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

NASA Astrophysics Data System (ADS)

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

Thakur, Shweta; Rai, Radheshyam; Tiwari, Ashutosh

2014-11-01

156

Synthesis, characterization and properties of microporous lanthanide silicates: K 8Ln 3Si 12O 32NO 3H 2O (Ln = Eu, Tb, Gd, Sm)  

NASA Astrophysics Data System (ADS)

A family of microporous lanthanide silicates, K 8Ln 3Si 12O 32NO 3H 2O (denoted LnSiO-CJ3, Ln = Eu, Tb, Gd, Sm), was synthesized under mild hydrothermal conditions at 503 K. The X-ray powder diffraction patterns of these compounds reveal that they are isostructural. The structure of EuSiO-CJ3 was determined by single-crystal X-ray diffraction analysis. It crystallizes in triclinic space group P-1 (No. 2) with a = 11.599(2) , b = 12.225(2) , c = 13.829(3) , ? = 112.99(3), ? = 92.05(3), ? = 90.57(3). The structure is based on [Si 3O 8] n4 n- layers with 6-, 8-, 12-rings that are connected by EuO 6 octahedra to form a 3-D framework with 8-ring channels along the [001] direction. Charge neutrality is achieved by the K + and NO 3- ions located in the channels. The framework of EuSiO-CJ3 shows good thermal stability, which can be stable up to 1273 K. Ion-exchange capacity of EuSiO-CJ3 was investigated by the exchange of NO 3- ions with halide ions (F -, Cl -, Br -). The peaks in the emission spectra of LnSiO-CJ3 (Ln = Eu, Tb) belong to the characteristic transitions of Ln 3+ (Ln = Eu, Tb) respectively. The lifetime measurements of LnSiO-CJ3 (Ln = Eu, Tb) suggest the presence of three Ln 3+ (Ln = Eu, Tb) environments, which are consistent with the crystallographic results.

Wang, Xi; Li, Jiyang; Wang, Guangmei; Han, Yide; Su, Tan; Li, Yi; Yu, Jihong; Xu, Ruren

2010-04-01

157

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)

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- ?m and 5- ?m. To evaluate luminescence efficiency and the spatial resolution according to the thickness, we fabricated screen films with thicknesses of 120, 150, 170, and 210- ?m. 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- ?m particles had better resolution than the screen with 5.0- ?m 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- ?m-thick screen showed the highest resolution, which was similar to that of a commercial screen.

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

2014-08-01

158

Q? measurements of 158, 159Pm , 159, 161Sm , 160-165Eu , 163Gd and 166Tb using a total absorption BGO detector  

NASA Astrophysics Data System (ADS)

Q ? values of the neutron-rich isotopes of 160-165Eu and 163Gd were measured for the first time using a total absorption bismuth germanate (BGO) detector, and previously obtained data on 158, 159Pm , 159, 161Sm and 166Tb were re-analyzed. These radioactive sources were prepared by an on-line mass separator (Tokai-ISOL) following the 238U (p, f reaction. The deduced Q ? values are the following: 6085(80)keV for 158Pm , 3805(65)keV for 159Sm , 5460(140)keV for 159Pm , 4705(60)keV for 160Eu , 5065(130)keV for 161Sm , 3705(60)keV for 161Eu , 5575(60)keV for 162Eu , 4690(70)keV for 163Eu , 3170(70)keV for 163Gd , 6430(70)keV for 164Eu , 5800(120)keV for 165Eu , and 4695(70)keV for 166Tb . Moreover, the deduced mass excesses and two-neutron separation energies ( S 2n values) were compared with those of the atomic mass evaluations and theoretical predictions.

Hayashi, H.; Akita, Y.; Suematsu, O.; Shibata, M.; Asai, M.; Sato, T. K.; Ichikawa, S.; Nishinaka, I.; Nagame, Y.; Osa, A.; Tsukada, K.; Ishii, T.; Kojima, Y.; Taniguchi, A.

2007-12-01

159

Thermal activation, cathodo- and photoluminescence measurements of rare earth doped (Tm, Tb, Dy, Eu, Sm, Yb) amorphous/nanocrystalline AlN thin films prepared by reactive rf-sputtering  

NASA Astrophysics Data System (ADS)

We present comprehensive cathodo- and photoluminescence measurements from thin amorphous/nanocrystalline (a/nc-) AlN films doped with rare earths. The (a/nc-) AlN films were prepared by reactive rf-sputtering using a high purity (5 N) aluminium disk in high purity nitrogen atmosphere (5 N, pressure ca. 1.3 mbar). The rare earth doping (Tm, Tb, Dy, Eu, Sm, Yb, concentrations were below 1%) was performed by placing respective rare earth metal pieces of appropriate size onto the aluminium disk. The rare earth ion emissions cover the blue (Tm), green (Tb), yellow (Dy), red (Sm, Eu) and infrared (Yb). The optical and related structural properties of the films are correlated by means of high resolution transmission electron microscopy in combination with cathodoluminescence measurements in a scanning electron microscope. In addition, the corresponding compositions are determined by energy-dispersive X-ray analysis. The cathodo- and photoluminescence spectra of the rare earth 3+ ions are recorded in the visible at 300 K in the as-grown condition (Tm, Tb, Dy, Sm, Eu, Yb) and after annealing treatments in the temperature range from 300 to 1100 C by steps of 150 C (Tb, Sm, Eu, Yb). The anneal-related changes in the cathodo- and photoluminescence emission spectra and in the microstructure of the films are addressed. The AlN films show nanocrystalline structure almost independent of the annealing treatment. Optimal annealing temperature for emissions of Sm and Eu doped (a/nc-) AlN were derived to be 900 C whereas Tb 3+ and Yb 3+ emissions increase at least up to 1100 C.

Weingrtner, R.; Erlenbach, O.; Winnacker, A.; Welte, A.; Brauer, I.; Mendel, H.; Strunk, H. P.; Ribeiro, C. T. M.; Zanatta, A. R.

2006-05-01

160

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

PubMed

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

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

2014-07-28

161

Effects of rare earth ions (Tb, Ce, Eu, Dy) on the thermoluminescence characteristics of sol-gel derived and ?-irradiated SiO2 nanoparticles.  

PubMed

Highly pure SiO2 and SiO2 :RE nanoparticles were synthesized by the sol-gel method. The morphological, structural and optical properties of the nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD results indicate that all the samples studied were free from impurities. SEM/TEM results indicate that the samples were well dispersed. Surface characterization of the nanocrystals by Fourier transform infrared spectroscopy has been carried out and the structure of surface-bound SiO2 based on spectral analysis is proposed. Thermoluminescence (TL) characteristics were investigated to study the influence of rare earth dopants (Tb, Ce, Eu, Dy) on SiO2 matrix subjected to 0.5?kG (1?h) ?-irradiation. Among these rare earth elements, Eu(3+) was found to be the most efficient dopant for SiO2 showing maximum thermoluminescence intensity. SiO2 :Eu0.5 seems to be a promising candidate for use as a TL dosimeter. PMID:24222272

Bajpai, Namrata; Tiwari, Ashish; Khan, S A; Kher, R S; Bramhe, Namita; Dhoble, S J

2014-09-01

162

Tunable color temperature solid state white light source using flux grown phosphor crystals of Eu3+, Dy3+ and Tb3+ activated calcium sodium molybdenum oxide  

NASA Astrophysics Data System (ADS)

Solid state light sources with dynamically tunable color temperature in the range of 3000-6000 K with chromaticity coordinates lying on the Planckian black body curve has been designed using mixtures of narrow emissions at 615 nm, 575 nm and 550 nm. These respective emissions lines were generated by individual phosphor crystals of trivalent rare earth (RE3+) species, europium (Eu3+), dysprosium (Dy3+) and terbium (Tb3+) activated calcium sodium molybdenum oxide (Ca1-2xNaxMoO4:RE3+x), when excited by near-ultra-violet (NUV) light emitting diode (LED) with emission wavelength of 380 nm. Highly luminescent crystals of these compounds have been grown from molten solutions (flux) of molybdenum (VI) oxide. The flux grown crystals exhibit emission intensity 2-4 times more than phosphor powders of the same compounds synthesized by traditional solid-state reactions. An optimum flux to solute ratio of 2.5 and solute dissolution temperature of 1100 C resulted in the largest size crystals.

Khanna, A.; Dutta, P. S.

2014-11-01

163

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)

The present work reports on the spectroscopic and rheological properties of un-exposed and gamma (?-) 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 ?-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 ?-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.

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

2013-10-01

164

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

165

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

166

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)

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 (?H) dependence of the P can be described by a formula P =P0-?sin2?H. As for GdFe3(BO3)4 and TbFe3(BO3)4, they show highly anisotropic ?H dependence of P, which characterizes the respective ME responses from their R magnetic moments. In certain regions of ?H, the P can be described by P =P0-Ksin2?H and P =P0??sin?H 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.

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

2014-05-01

167

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

NASA Technical Reports Server (NTRS)

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.

Flood, D. J.

1973-01-01

168

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

PubMed

Reactions of [Mn6O2(piv)10(py)2.5(piv)1.5], Ln(NO3)36H2O and N-mdeaH2 in MeCN in the presence of Me3SiCl generated a family of octanuclear Mn/Ln complexes [Mn6(III)Mn(II)Ln(N-mdea)3(N-mdeaH)(piv)8O2(OH)3(NO3)(H2O)]xCH3CNxH2O [Ln = Gd (1), Dy (2), Er (3), pivH = pivalic acid, N-mdeaH2 = N-methyl diethanolamine]. Each complex possesses a [Mn6(III)Mn(II)Ln(?3-O)2(?3-OH)3](16+) core containing two butterfly-like subunits of [Mn3Ln(?3-OH)2] and [Mn4(?3-O)2] sharing a common vertex, and an outer Mn atom ligated to one of the subunits through a ?3-OH(-) ligand. The core topology represents a new Mn/Ln core type. The magnetic susceptibility study of 1-3 indicates the presence of dominant antiferromagnetic interactions within the complexes. For complex 1, which contains an isotropic Gd(III) atom, fitting of the obtained M/(N?B) vs. H/T data gave S = 4, g = 1.90, and D = -0.31 cm(-1). The results were further supported by ac data. Complex exhibits out-of-phase ac susceptibility signals, indicating it may be a SMM. PMID:23377042

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

2013-04-14

169

Antiferromagnetic behaviour of Tb2Al alloy  

NASA Astrophysics Data System (ADS)

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).

Rojas, D. P.; Andr, G.; Rodrguez Fernndez, J.; Snchez Marcos, J.; Fernndez Barqun, L.; Echevarria, C.

2011-10-01

170

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

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.

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

2012-08-15

171

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)

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

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

2014-10-01

172

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

NASA Astrophysics Data System (ADS)

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.

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

2015-02-01

173

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)

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

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

2015-01-01

174

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

175

Green long-after-glow luminescence of Tb3+ in Sr2SiO4  

NASA Astrophysics Data System (ADS)

The green long-after-glow luminescence from Tb3+-doped Sr2SiO4 phosphors, which are synthesized by the high temperature solid state reaction in a reductive atmosphere, is observed in this paper. The results show that under ultraviolet excitation, the obtained phosphors produce an intense green-lighting-emission from the Tb3+, and the green-lighting long-after-glow luminescence related to Tb3+ can last half an hour after the irradiation source has been removed. Moreover, the effects of co-doping Li+, Dy3+, Er3+, Gd3+, and Yb3+ with Tb3+ on the decay properties and thermoluminescence properties are investigated to confirm the long-after-glow mechanism.

Wang, Qi; Qiu, Jian-Bei; Song, Zhi-Guo; Zhou, Da-Cheng; Xu, Xu-Hui

2014-06-01

176

Corrosion study of single crystal Ni-Mn-Ga alloy and Tb0.27Dy0.73Fe1.95 alloy for the design of new medical microdevices.  

PubMed

Once placed in a magnetic field, smart magnetic materials (SMM) change their shape, which could be use for the development of smaller minimally invasive surgery devices activated by magnetic field. However, the potential degradation and release of cytotoxic ions by SMM corrosion has to be determined. This paper evaluates the corrosion resistance of two SMM: a single crystal Ni-Mn-Ga alloy and Tb(0.27)Dy(0.73)Fe(1.95) alloy. Ni-Mn-Ga alloy displayed a corrosion potential (E (corr)) of -0.58V/SCE and a corrosion current density (i (corr)) of 0.43 ?A/cm(2). During the corrosion assay, Ni-Mn-Ga sample surface was partially protected; local pits were formed on 20% of the surface and nickel ions were mainly found in the electrolyte. Tb(0.27)Dy(0.73)Fe(1.95) alloy exhibited poor corrosion properties such as E (corr) of -0.87V/SCE and i (corr) of 5.90 ?A/cm(2). During the corrosion test, this alloy was continuously degraded, its surface was impaired by pits and cracks extensively and a high amount of iron ions was measured in the electrolyte. These alloys exhibited low corrosion parameters and a selective degradation in the electrolyte. They could only be used for medical applications if they are coated with high strain biocompatible materials or embedded in composites to prevent direct contact with physiological fluids. PMID:21222141

Pouponneau, Pierre; Savadogo, Oumarou; Napporn, Teko; Yahia, L'Hocine; Martel, Sylvain

2011-02-01

177

Hydrothermal Synthesis, Structure, and Optical Properties of Two Nanosized Ln26 @CO3 (Ln=Dy and Tb) Cluster-Based Lanthanide-Transition-Metal-Organic Frameworks (Ln MOFs).  

PubMed

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

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

2015-02-16

178

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

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 PrDy 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 PrDy 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.

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

2013-09-15

179

Gamma-Ray Spectroscopy for Neutron-Rich A?160-170 Nuclei:. the ?- Decay of 159PM, 160-162SM, 162EU, 164-166GD, and 166-168TB  

NASA Astrophysics Data System (ADS)

?- decays of neutron-rich A?160-170 nuclei 159Pm, 160-162Sm, 162Eu, 164-166Gd, and 166-168Tb have been studied through ?-ray spectroscopy using an on-line isotope separator. These nuclei were produced by the 15-20 MeV proton induced fission of 238U. Excited states of their daughter nuclei have been established.

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

2003-10-01

180

A new type of silica-coated Gd?(CO?)?:Tb nanoparticle as a bifunctional agent for magnetic resonance imaging and fluorescent imaging.  

PubMed

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 Gd(2)(CO(3))(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 T(1)-weighted effect and could potentially serve as a bimodal T(1)-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. PMID:22543843

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

2012-05-25

181

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)

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 nanoprobes 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.

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

2012-05-01

182

?-NaGdF4 nanotubes: one-pot synthesis and luminescence properties.  

PubMed

Hexagonal-phase NaGdF4 nanotubes were successfully fabricated through a template- and catalyst-free method in a hydrothermal environment. The intrinsic and external factors contributing to the formation of tubular nanocrystals were discussed, namely the anisotropic crystal structure of the hexagonal-phase NaGdF4 and the insufficient supply of reagents. Furthermore, the addition of ethylene glycol and hydrazine had a significant effect on the morphological variation. The desirable multicolor outputs were achieved by co-doping Ce(3+) and Ln(3+) (Ln = Eu, Tb, and Dy) ions in the NaGdF4 crystal, in which the Gd(3+) ions acted as an intermediate medium transforming the excitation energy to the activator ions. Finally, the upconversion luminescence and magnetic performance of the sodium rare earth fluoride were demonstrated. PMID:25607346

Zhao, Qi; Shao, Baiqi; L, Wei; Lv, Wenzhen; Jiao, Mengmeng; Zhao, Lingfei; You, Hongpeng

2015-02-10

183

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

SciTech Connect

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

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

2012-12-15

184

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

PubMed

The reaction of N-methydiethanolamine (mdeaH2), benzoic acid, FeCl3, and Ln(NO3)36H2O or LnCl3xH2O yields a series of decanuclear coordination clusters, [Ln3Fe7(?4-O)2(?3-OH)2(mdea)7(?-benzoate)4(N3)6]4MeCNH2O, where Ln = Gd(III) (1) or Tb(III) (2), and [Er3Fe7(?4-O)2(?3-OH)2(mdea)7(?-benzoate)4(N3)5(MeOH)]Cl7.5H2O11.5MeOH (3). The isostructural compounds 1-3 all crystallize isotypically in the triclinic space group P1? with Z = 2, as does the previously reported dysprosium analogue 4. Six of the Fe(III) ions are pseudooctahedrally coordinated, whereas the seventh has a trigonal-bipyramidal coordination geometry. Temperature-dependent direct-current magnetic susceptibility studies indicate that intracluster antiferromagnetic interactions are dominant in 1-3. The frequency-dependent out-of-phase (??) alternating-current susceptibility reveals that 2 undergoes a slow relaxation of its magnetization, presumably resulting from anisotropy of the Tb(III) ions. Between 30 and 295 K, the (57)Fe Mssbauer spectra reveal paramagnetic behavior with six partially resolved quadrupole doublets, one for the trigonal-bipyramidal Fe(III) site and five for the six pseudooctahedral Fe(III) sites. The Mssbauer spectra of 2 and 3 obtained between 3 and 30 K are consistent with the presence of Fe(III) intracluster antiferromagnetic coupling with slow magnetic relaxation relative to the Larmor precession time. Further, the observed changes in the effective magnetic field values in the spectra measured at 3 K with increasing applied field are consistent with the effect of the local spin polarization along the applied magnetic field direction, a behavior reminiscent of antiparallel spin-coupled iron molecular paramagnetic systems. PMID:24089701

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

2013-10-21

185

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

PubMed

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

Heine, Johanna; Wehner, Tobias; Bertermann, Rdiger; Steffen, Andreas; Mller-Buschbaum, Klaus

2014-07-21

186

Syntheses and Structures of the New Quaternary Compounds Ba 4Nd 2Cd 3Se 10 and Ba 4Ln2Cd 3S 10 ( Ln=Sm, Gd, Tb)  

NASA Astrophysics Data System (ADS)

The compounds Ba4Nd2Cd3Se10 and Ba4Ln2Cd3S10 (Ln=Sm, Gd, Tb) have been synthesized at 1173 K with the use of a BaBr2/KBr eutectic flux. These isostructural compounds crystallize as racemic twins in space group Cmc21 of the orthorhombic system in cells of (Ln, Q, a, b, c (), T (K)): Nd, Se, 4.3340(9), 18.667(4), 27.376(6), 115; Sm, S, 4.1907(8), 17.931(4), 26.594(5), 153; Gd, S, 4.1726(4), 17.928(2), 26.638(3), 153; Tb, S, 4.1643(8), 17.916(4), 26.581(5), 153. The corresponding R1 indices for the refined structures are 0.053, 0.029, 0.032, and 0.030. The structure comprises [Ln2Cd3Q10]4- layers interconnected by Ba atoms. There are LnQ6 octahedra and severely distorted CdQ4 tetrahedra in the structure. Ba4Tb2Cd3S10, which is paramagnetic, obeys the Curie-Weiss law and has an effective magnetic moment of 9.94(3) ?B. A band gap of 3.0 eV for this material was deduced from its diffuse reflectance spectrum.

Yang, Yuting; Ibers, James A.

2000-02-01

187

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

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.

Cao Chunyan [College of Mathematics and Physics, Jinggangshan University, Ji'an 343009 (China); Yang, Hyun Kyoung; Moon, Byung Kee; Choi, Byung Chun [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of); Jeong, Jung Hyun, E-mail: jhjeong@pknu.ac.kr [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of); Kim, Kwang Ho, E-mail: kwhokim@pusan.ac.kr [School of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of)

2012-03-15

188

Effect of cation size and size-disorder on the magnetic and electron transport properties of La 0.7- xLn xSr 0.3MnO 3 (Ln=Gd and Dy)  

NASA Astrophysics Data System (ADS)

Magnetic and electron transport properties of La 0.7- xLn xSr 0.3MnO 3 with Ln=Gd and Dy have been investigated over a wide range of compositions to explore the effects of the radius of the A-site cation, < rA>, and the size-disorder as measured by ?2. These manganates exhibit ferromagnetism and insulator-metal transitions up to a critical value of x ( xc), with the Tc ( TIM) values decreasing with < rA>. When x? xc, however, the manganates cease to be ferromagnetic and instead they show an abrupt decrease in magnetization and increase in resistivity, suggesting the likely occurrence of electronic phase separation.

Motin Seikh, Md.; Sudheendra, L.; Rao, C. N. R.

2004-06-01

189

DyMnSi as a representative of family of DyTransition MetalSi systems: Its isothermal sections, empirical rProd. Type: FTPules and new rare-earth manganese silicides  

SciTech Connect

X-ray and microprobe analyses were employed for the investigation of DyMnSi system at 870/1070/1170 K. The DyMnSi system, contains the known DyMn{sub 2}Si{sub 2}, DyMnSi and Dy{sub 2}Mn{sub 3}Si{sub 5} compounds and DyMn{sub 4}Si{sub 2}, Dy{sub 2}MnSi{sub 2} and Dy{sub 3}Mn{sub 2}Si{sub 3} were new compounds identified first time and their structure are of the type TmCu{sub 4}Sb{sub 2}, Sc{sub 2}CoSi{sub 2} and Hf{sub 3}Ni{sub 2}Si{sub 3} respectively. The quasi-binary solid solutions were detected at 870/1070/1170 K: the ThMn{sub 12}-type Dy{sub 8}Mn{sub 87}Si{sub 5}, Th{sub 6}Mn{sub 23}-type Dy{sub 23}Mn{sub 72}Si{sub 5}, MgCu{sub 2}-type Dy{sub 33}Mn{sub 58}Si{sub 9} and AlB{sub 2}-type Dy{sub 38}Mn{sub 2}Si{sub 58}. The other binary compounds of the DyMnSi system do not show any visible solubility. New phases R{sub 2}MnSi{sub 2} and R{sub 3}Mn{sub 2}Si{sub 3} (R=Gd, Tb, HoTm) were found out and their structure of the type Sc{sub 2}CoSi{sub 2} and Hf{sub 3}Ni{sub 2}Si{sub 3} respectively. The specific features of DyTransition MetalSi systems were discussed. - Graphical abstract: The isothermal section of DyMnSi contains the known DyMn{sub 2}Si{sub 2}, DyMnSi, Dy{sub 2}Mn{sub 3}Si{sub 5} and new TmCu{sub 4}Sb{sub 2}-type DyMn{sub 4}Si{sub 2}, Sc{sub 2}CoSi{sub 2}-type Dy{sub 2}MnSi{sub 2} and Hf{sub 3}Ni{sub 2}Si{sub 3}-type Dy{sub 3}Mn{sub 2}Si{sub 3} ternary compounds. The ternary solid solution based on the binary compounds of the DyMn and DySi systems: the ThMn{sub 12}-type Dy{sub 8}Mn{sub 87}Si{sub 5}, Th{sub 6}Mn{sub 23}-type Dy{sub 23}Mn{sub 72}Si{sub 5}, MgCu{sub 2}-type Dy{sub 33}Mn{sub 58}Si{sub 9} and AlB{sub 2}-type Dy{sub 38}Mn{sub 2}Si{sub 58}. The other binary compounds of the DyMnSi system do not show any visible solubility. New Sc{sub 2}CoSi{sub 2}-type R{sub 2}MnSi{sub 2} and Hf{sub 3}Ni{sub 2}Si{sub 3}-type R{sub 3}Mn{sub 2}Si{sub 3} phases were discovered for R=Gd, Tb, HoTm. Display Omitted - Highlights: The DyMnSi section contains three known and three new ternary compounds (phases). New phase the TmCu{sub 4}Sb{sub 2}-type DyMn{sub 4}Si{sub 2} compound. New Sc{sub 2}CoSi{sub 2}-type R{sub 2}MnSi{sub 2} and Hf{sub 3}Ni{sub 2}Si{sub 3}-type R{sub 3}Mn{sub 2}Si{sub 3} were detected for R=GdTm. DyMnSi supplements the Dy3d metalSi series and leads to the RT{sub m}X{sub n} row's rule.

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

2013-10-15

190

Light collection enhancement of the digital x-ray detector using Gd 2O 2S:Tb and CsI:Tl phosphors in the aspect of nano-scale light dispersions  

NASA Astrophysics Data System (ADS)

The nano-scopic light collection is investigated for the Active Matrix Flat-Panel Imagers (AMFPIs). The simulations using two kinds of screens are shown for light collection of x-rays. Enhancement of the light collection is accomplished by the microlens system incorporated with x-ray detector. For digital radiographic and mammographic applications, indirect detection imagers use Gd 2O 2S:Tb or CsI:Tl scintillation screens to convert the x-ray into visible photons. The light collection efficiencies for Gd 2O 2S and CsI are obtained. In Gd 2O 2S, the 27 kVp and 82 ?m are the highest light collection cases in both Lambertian and Isotropic geometries. In CsI, 20 keV and 150 ?m case have the highest light collection efficiency. So, x-ray energy and scintillator thicknesses are considered as the optimized light collection. The optimum thickness and x-ray energy combination are used for the detector of this study. In this paper, it is concluded that the screens between 17 kVp and 25 kVp have higher light collections, which could be considered as the clinical purposes if it is necessary. This energy range is compared with other energy cases, which are examined in the study.

Woo, Taeho; Kim, Taewoo

2012-01-01

191

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

NASA Astrophysics Data System (ADS)

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 ?Sm 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 Mssbauer 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 Mssbauer 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.

Schfer, Konrad; Schwickert, Christian; Niehaus, Oliver; Winter, Florian; Pttgen, Rainer

2014-09-01

192

Blue light emitting SrSn(OH){sub 6} nano-rods doped with lanthanide ions (Eu{sup 3+}, Tb{sup 3+} and Dy{sup 3+})  

SciTech Connect

Graphical abstract: Display Omitted Highlights: ? Room temperature synthesis of blue light emitting SrSn(OH){sub 6} nano-rods. ? Blue light emission originates from the recombination of self trapped excitons. ? There exists energy transfer from host to lanthanide ions in SrSn(OH){sub 6}:Ln nano-rods. ? Solubility of Eu{sup 3+} ions in SrSn(OH){sub 6} nano-rods is around 1.5 at%. -- Abstract: Blue light emitting SrSn(OH){sub 6} nano-rods were prepared in aqueous medium at room temperature. Presence of lanthanide ions in reaction medium during synthesis of nano-rods, leads to significant changes in the morphology of the nano-rods. Based on luminescence studies emission in the blue region from SrSn(OH){sub 6} nano-rods has been attributed to radiative recombination of self trapped excitons in the lattice. SrSn(OH){sub 6} nano-rods were doped with lanthanide ions like Eu{sup 3+}, Tb{sup 3+} and Dy{sup 3+} and their luminescence studies revealed that there exists energy transfer from host to lanthanide ions. From the luminescence studies on Eu{sup 3+} doped samples, it is confirmed that up to 1.5 at%, Eu{sup 3+} ions get incorporated at Sr{sup 2+} site in SrSn(OH){sub 6} lattice and beyond which a separate Eu{sup 3+} containing phase is formed. Part of the europium ions also exists as Eu{sup 2+} species in the lattice as confirmed by electron paramagnetic resonance (EPR) studies.

Patel, D.K.; Nuwad, J. [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)] [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Rajeswari, B. [Radio Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)] [Radio Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Vishwanadh, B. [Materials Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)] [Materials Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Sudarsan, V.; Vatsa, R.K. [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)] [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Kadam, R.M. [Radio Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)] [Radio Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Pillai, C.G.S. [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)] [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Kulshreshtha, S.K., E-mail: kulshres@gmail.com [Knowledge Management Group, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

2013-02-15

193

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

194

An investigation of the structures of the compounds in the tin-rich part of the DySn system: Crystal structure of Dy 5Sn 11 and Dy 5Sn 13  

Microsoft Academic Search

The structural properties of the compounds in the tin-rich part of the dysprosiumtin system have been studied by X-ray powder diffraction. The crystal structures of six compounds DySn2+x (0DySn2 with the ZrSi2 structure, Dy3Sn7 with the Gd3Sn7 structure, Dy2Sn5 with the Er2Ge5 structure, DySn3 with the DyGe3 structure

G. Venturini; A. Mesbah

2008-01-01

195

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

196

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)

The experimental variations in the spontaneous polarization ?Ps(T) and pyroelectric coefficient ?s(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 ?Ps at T > 85 K and distinct anomalies are observed in ?s(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 (42m), is discussed in terms of this model.

Matyjasik, S.; Shaldin, Yu. V.

2013-11-01

197

Crystal structure and magnetic properties of novel R{sub 3}Co{sub 2.2}Si{sub 1.8} compounds (R=Y, Gd-Tm)  

SciTech Connect

The crystal structure of new ternary Dy{sub 3}Co{sub 2.2}Si{sub 1.8} compound has been established using single crystal X-ray diffraction, and those of R{sub 3}Co{sub 2.2}Si{sub 1.8} phases (R=Y, Gd-Tm) phases have been verified through the powder diffraction techniques. The Dy{sub 3}Co{sub 2.2}Si{sub 1.8} structure is a new structure type, which is obtained from the Er{sub 3}Ge{sub 4} with an ordered Er{sub 3}Ge{sub 4}-type structure (space group Cmcm) one by coloring the two Ge sites, 4a and 4c, with Si and the 8f site with Co atoms. Tb{sub 3}Co{sub 2.2}Si{sub 1.8}, Dy{sub 3}Co{sub 2.2}Si{sub 1.8}, Ho{sub 3}Co{sub 2.2}Si{sub 1.8} and Er{sub 3}Co{sub 2.2}Si{sub 1.8} compounds display ferromagnetic-type ordering. - Graphical abstract: The novel R{sub 3}Co{sub 2.2}Si{sub 1.8} compounds (R=Y, Gd-Tm) adopt the new structure type, the ordered variant of Er{sub 3}Ge{sub 4}-type structure Magnetic studies on {l_brace}Tb, Dy, Ho, Er{r_brace}{sub 3}Co{sub 2.2}Si{sub 1.8} suggest that their magnetic interactions are primarily ferromagnetic in nature. Highlights: Black-Right-Pointing-Pointer The novel {l_brace}Y, Gd-Tm{r_brace}{sub 3}Co{sub 2.2}Si{sub 1.8} compounds adopt the Dy{sub 3}Co{sub 2.2}Si{sub 1.8} structure type, Black-Right-Pointing-Pointer The Dy{sub 3}Co{sub 2.2}Si{sub 1.8} type is ordered variant of Er{sub 3}Ge{sub 4} type structure. Black-Right-Pointing-Pointer {l_brace}Gd-Tm{r_brace}{sub 3}Co{sub 2.2}Si{sub 1.8} compounds are primarily ferromagnetic in nature.

Morozkin, A.V., E-mail: morozkin@general.chem.msu.ru [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, Moscow GSP-2 119992 (Russian Federation); Yao, Jinlei; Mozharivskyj, Y. [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Canada, Ontario L8S 4M1 (Canada)

2012-08-15

198

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

SciTech Connect

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

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

2014-07-01

199

Normal coordinate analysis and DFT calculations of the vibrational spectra for lanthanide(III) complexes with 3-bromo-4-methoxy-2,6-lutidine N-oxide: LnCl 3(3Br4CH 3OC 7H 7NO) 3 (Ln=Pr, Nd, Sm, Eu, Gd, Dy)  

NASA Astrophysics Data System (ADS)

The results of the FT-Raman and FT-IR studies of the LnCl 3(LNO) 3 type complexes (where Ln=Pr, Nd, Sm, Eu, Gd, Dy and LNO=3-Br-4-CH 3OC 7H 7NO) are presented. The spectral contours observed in the regions of the lanthanide-oxygen, lanthanide-chlorine and nitrogen-oxygen vibrations are employed in the discussion of the molecular structure of the complex ions and the local symmetry of the LnCl 3(ON) 3 polyhedron. The discussion of the vibrational spectra is based on the classical normal coordinate analysis and its results are compared to the results of DFT quantum chemical calculations performed for complete molecule. The normal coordinate analysis has been performed for PrCl 3(ON) 3 and DyCl 3(ON) 3 molecular systems, which have been treated as a different 'isotopic units'. Basing on the predominant PED contributions of the respective internal coordinates the assignment of the normal vibrations has been proposed.

Godlewska, P.; Ban-Oganowska, H.; Macalik, L.; Hanuza, J.; Oganowski, W.; Roszak, S.; Lipkowski, P.

2006-01-01

200

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

Invited for the cover of this issue is the group of Yu Zhang 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

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

2014-12-01

201

Investigation of annealed and metamict pyrochlore minerals by x-ray absorption spectroscopy. [Synthetic pyrochlores with general formula (RE)/sub 2/Ti/sub 2/O/sub 7/, RE = Er, Y/sub 2/, Gd/sub 2/, Dy, La  

SciTech Connect

Materials of the pyrochlore structure type exhibit a variety of interesting properties including phases capable of acting as hosts for actinides in radioactive wastes. Studies of curium doped gadolinium titanate phases (Gd/sub 2/Ti/sub 2/O/sub 7/) have been made which showed that the radiation damage ingrowth followed an exponential relationship. For the study reported here a series of synthetic pyrochlores were produced having the titanate phase with the general formula (RE)/sub 2/Ti/sub 2/O/sub 7/, RE = Er, Y/sub 2/, Gd/sub 2/, Dy, La. Additionally a set of metamict (radiation damaged) pyrochlores was examined in both a natural and post temperature annealed state. Experiments were conducted on these samples using the Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Structure (XANES) techniques. In summary, these studies show that in pyrochlore structure types the Ti-O cage undergoes changes due to radiation damage. The individual Ti-O bonds become more disordered which leads to a loss of short and long range order and, ultimately, to expansion of the bulk material. 2 refs., 2 figs.

Greegor, R.B.; Lytle, F.W.; Ewing, R.C.; Chakoumakos, B.C.; Lumpkin, G.R.

1984-01-01

202

New rare earth silicate crystals: Dy 2 MoSi 2 Al 4 O 16 , compounds in the systems R 2 O 3 SiO 2 -PbO, and a new form of R 2 SiO 5  

Microsoft Academic Search

The growth of crystals of a new cubic compound, Dy2MoSi2Al4O16, and of R2SiO5 (R=Dy, Tb, Gd) with a new structure is reported. Flux growth studies in the systems R2O3-SiO2-PbO are also described. These have yielded single crystals of two new families of compounds: PbR4Si5O17, with a monoclinic structure, and apatite-related phases of composition between Pb1.4Er2.93Si3.6O13 and Pb1.8Er2.5Si3.7O13 for R=Er. The

B. M. Wanklyn; F. R. Wondre; G. B. Ansell; W. Davison

1975-01-01

203

Theoretical Investigation on the Phase Stability and Site Preference of R(Co,T)12 and R(Co,T)12Nx (R=Y, Ce, Pr, Nd, Sm, Gd, Tb, Ho, Er, Dy, T=Mo, Mn, Ni)  

NASA Astrophysics Data System (ADS)

The phase stability and site preference of some ternary elements of ThMn12 type rare-earth intermetallic compounds R(Co,T)12 and R(Co,T)12Nx are evaluated based on ab initio converted interatomic potentials. The calculated results show that adding either Mo or Mn makes the crystal cohesive energy decrease markedly. It proved that these elements can stabilize R(Co,T)12 with ThMn12 structure. The systemic energy is the lowest when T atoms occupy symmetrically 8i sites. For T=Mo or Mn, the doped nitrogen atom does not affect the order of site preference of these stabilizing elements. Moreover, the nitrogen atom occupies 2b sites. According to the calculated results, it can be seen that lattice parameters and X-rays are in good agreement with experiment. All the above results indicate that the ab initio converted pair potentials are effective for the calculation of these kinds of anisotropy materials and some related nitrides.

Shen, Jiang; Qian, Ping; Chen, Nan-Xian

204

Theoretical Investigation on the Phase Stability and Site Preference of R(Co,T)>12 and R(Co,T)12Nx (R = Y, Ce, Pr, Nd, Sm, Gd, Tb, Ho, Er, Dy, T = Mo, Mn, Ni)  

NASA Astrophysics Data System (ADS)

The phase stability and site preference of some ternary elements of ThMn12 type rare-earth intermetallic compounds R(Co,T)12 and R(Co,T)12Nx are evaluated based on ab initio converted interatomic potentials. The calculated results show that adding either Mo or Mn makes the crystal cohesive energy decrease markedly. It proved that these elements can stabilize R(Co,T)12 with the ThMn12 structure. The systemic energy is the lowest when T atoms occupy symmetrically 8i sites. For T = Mo or Mn, the doped nitrogen atom does not affect the order of site preference of these stabilizing elements. Moreover, the nitrogen atom occupies 2b sites. According to the calculated results, it can be seen that lattice parameters and X-ray patterns are in good agreement with experiment. All the above results indicate that the ab initio converted pair potentials are effective for the calculation of these kinds of anisotropy materials and some related nitrides.

Shen, Jiang; Qian, Ping; Chen, Nan-Xian

205

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

NASA Astrophysics Data System (ADS)

From accurate measurement of magnetic susceptibility K of powder sample and single crystal of cubic Dy 2Ti 2O 7 (DyT) between 300 and 70 K, a change of slope of 1/ K was detected at 130 K because of crystal field (CF) effect. For analysing K, Mssbauer spectra and other available results on DyT consistently, the full form of the D 3d symmetry of CF was considered and J-mixing of the intermediately coupled states due to CF was done. The best fitted CF parameters were found as B 20=-880, B 40=-110, B 60=1040 , B 43=120, B 63=175, B 66=-1900 (all in cm -1). The corresponding multiplet of the ground 6H 15/2 has a lowest CF doublet level, well separated from the next doublet level (?100 cm-1) for which reason giant magnetostriction in DyT was not observed, unlike in TbT for which ?12 cm-1. Using the best fitted electronic and nuclear energy patterns, different quantities were calculated, viz., the Curie constant, saturated magnetisation and saturated magnetic moment per Dy spin at low temperatures, the values of which were respectively, 9 emu K/g ion, 3.7410 5 A/m, 4.7 ? B, being close to the measured values, g? value of ground doublet, which was reduced by 8% from the free ion value, and the quadrupolar interaction parameter, which was nearly zero at 110 K and attained a constant value of 124030 MHz at 4 K as observed. The hyperfine magnetic field Heff and the internal molecular field Hmol were found to be 540 and 0.2 T, respectively at 4 K. The calculated value of the single ion magnetic anisotropy ? K at low temperature was larger in DyT compared to HoT. Calculations also showed that compared to the classical Heisenberg exchange interaction (HEI), the ferromagnetic n.n. dipolar interaction (FDI) dominates in DyT being respectively, 1.53 and 0.3 K, whereas in HoT and in GdT the ratio between these interactions are much reduced. The magnetic energy gains associated with FDI and HEI were calculated and found to be 1.66 and 0.6 K, respectively. The large values of ? K and FDI, and weak HEI, are expected to make DyT a spin-ice system even at 0.2 K.

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

2002-07-01

206

Crystal and molecular structures of the 4-(1H)-pyridone (=L) lanthanide complexes [l brace][GdL(NO[sub 3])[sub 3](H[sub 2]O)][center dot]CH[sub 3]OH[r brace][sub 2] and [DyL[sub 4](NO[sub 3])[sub 2  

SciTech Connect

The crystal structures of the title compounds have been determined by single crystal diffraction methods. Crystals of the dysprosium compound are monoclinic, space group P2[sub 1]/c with a = 14.133(4), b = 13.438(5), c = 14.401(4) [Angstrom], [beta] = 103.98(2)[degrees], V = 2654(1) [Angstrom][sup 3], Z = 4, D[sub c] = 1.82 g cm[sup [minus]3], final R = 0.035. The Dy atom is eight-coordinate with a distorted dodecahedral coordination geometry involving two bidentate nitrate groups and four pyridone oxygen atoms. An erbium complex with analogous stoichiometry was also prepared but not structurally characterized. Crystals of the Gd compound are monoclinic, space group P2[sub 1]/n, with a = 11.226(2), b = 9.075(2), c = 16.737(3) [Angstrom], [beta] = 93.88(3)[degrees], V = 1701(1) [Angstrom][sup 3], Z = 2, D[sub c] = 1.91 g cm[sup [minus]3], final R = 0.042. Each Gd atom is bonded to one pyridone oxygen atom, a water molecule and three bidentate nitrate groups. An oxygen atom of one of the bidentate nitrates additionally serves to bridge pairs of Gd atoms so as to form a dinuclear complex in which each Gd atom is nine-coordinate with a tricapped trigonal prismatic geometry. Crystals of L[sub 2]HNO[sub 3] are monoclinic, space group I2/a with a = 12.479(4), b = 6.535(2), c = 14.297(6) [Angstrom], [beta] = 96.07(3)[degrees], V = 1159(1) [Angstrom][sup 3], Z = 4, D[sub c] = 1.45 g cm[sup [minus]3], final R = 0.057. The pyridones are linked in pairs by very short (2.44 [Angstrom]) symmetrical O[center dot][center dot][center dot]H[center dot][center dot][center dot]O hydrogen bonds. Each pair is further linked via a nitrate ion by means of N-H[center dot][center dot][center dot]O(nitrate)[center dot][center dot][center dot]H-N hydrogen bonds, so as to form an extended chevron-like pyridone-pyridone-nitrate-pyridone-pyridone array. Adjacent chains are linked via weak C-H[center dot][center dot][center dot]O(NO[sub 3]) interactions. 5 refs., 7 figs., 7 tabs.

Goodgame, D.M.L.; Lalia-Kantouri, M.; Williams, D.J. (Imperial College of Science, London (United Kingdom))

1993-05-01

207

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

SciTech Connect

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

Leung, Chung Ming; Or, Siu Wing; Zhang, Shengyao; Ho, S. L. [Department of Electrical Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong)

2010-05-15

208

Tuberculosis Facts - Exposure to TB  

MedlinePLUS

... STD, and TB Prevention Division of Tuberculosis Elimination 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 ...

209

Tuberculosis Facts - Testing for TB  

MedlinePLUS

... STD, and TB Prevention Division of Tuberculosis Elimination 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 ...

210

Isothermal Section of the Co-Gd-Sn Ternary System Between 0 and 55at.% Sn at 500C  

Microsoft Academic Search

The isothermal section of the Co-Gd-Sn system between 0 and 55at.% Sn at 500C was investigated by means of powder x-ray\\u000a diffraction. Five ternary phases were identified or confirmed: Gd6Co2Sn, Gd3Co8Sn4, Gd3Co6Sn5, Gd4CoSn8, and Gd3Co4Sn13. A new ternary phase Gd117Co57Sn112 with Dy117Co57Sn112-type structure, space group $$ Fm\\\\bar{3}m $$, and lattice parameter a=3.0023 (4) nm was found. The ternary rare earth

J. L. Yan; Y. Xu; Q. X. Long; J. M. Zhu; Y. H. Zhuang

2009-01-01

211

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

SciTech Connect

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.

Retot, H.; Viana, B. [Chimie Paristech, Laboratoire de Chimie Matiere Condensee de Paris, UPMC, College de France, UMR - CNRS 7574, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Bessiere, A. [Chimie Paristech, Laboratoire de Chimie Matiere Condensee de Paris, UPMC, College de France, UMR - CNRS 7574, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Department of Physics, Goa University, Taleigao Plateau, Goa 403 206 (India); Galtayries, A. [Chimie Paristech, Laboratoire de Physico-Chimie des Surfaces, UMR - CNRS 7045, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France)

2011-06-15

212

TB and Antibiotic Resistance  

NSDL National Science Digital Library

How does the development of antibiotic resistant strains of TB influence modern healthcare practices? We will consider genetic, environmental, epidemiological, and social perspectives of this renewed threat to public health. The TB simulation allows us to experiment with several TB strains and the antibiotics used to treat TB as we explore antibiotic resistance. * use sequence information to develop a protocol for treating antibiotic resistant TB

Marion Fass (Beloit College; Biology)

2006-05-20

213

Electronic structure studies of DyNi4Cu  

NASA Astrophysics Data System (ADS)

Electronic structure of the DyNi4Cu compound, crystallising in the hexagonal CaCu5-type of structure has been studied using the XPS method as well as the self-consistent spin-polarised TB-LMTO (tigh-binding linear muffin-tin orbital) method. Our calculations show that DyNi4Cu is ferromagnetically ordered at 0 K. The analysis of the valence band shape in vicinity of the Fermi level shows that this part of the spectrum comes mainly from 3d electrons of Ni and Cu atoms. The features of the experimental XPS valence band spectra near the Fermi level are reproduced in our calculations. Peaks below -7.5 eV are connected with the contribution of the f -electrons of Dy. The obtained peak positions in the valence band are in good agreement with the binding energies of metallic dysprosium, copper and nickel.

Pugaczowa-Michalska, M.; Chekowska, G.; Toliski, T.; Kowalczyk, A.

2006-01-01

214

Bose-Einstein condensation of 162Dy and 160Dy  

E-print Network

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

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

2014-11-12

215

Tuberculosis Facts - TB and HIV/AIDS  

MedlinePLUS

... STD, and TB Prevention Division of Tuberculosis Elimination 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 ...

216

Tuberculosis Facts - You Can Prevent TB  

MedlinePLUS

... STD, and TB Prevention Division of Tuberculosis Elimination 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 ...

217

Tuberculosis Facts - TB Can Be Treated  

MedlinePLUS

... STD, and TB Prevention Division of Tuberculosis Elimination 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 ...

218

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)

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) , c=15.861(1) , Z=2, R1=0.041 (w R2=0.088) for 1023 reflections with Io>2 ?( Io); Er 15B 4C 14: a=7.932(1) , c=15.685(2) , Z=2, R1=0.037 (w R2=0.094) for 1022 reflections with Io>2 ?( 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-) 4e -. The electronic structure was studied with the extended Hckel 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.

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

2010-10-01

219

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

PubMed

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

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

2014-02-14

220

TB Is Back.  

ERIC Educational Resources Information Center

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

Natale, Jo Anna

1992-01-01

221

Structural, Spectroscopic, and Theoretical Comparison of Traditional vs Recently Discovered Ln(2+) Ions in the [K(2.2.2-cryptand)][(C5H4SiMe3)3Ln] Complexes: The Variable Nature of Dy(2+) and Nd(2+).  

PubMed

The Ln(3+) and Ln(2+) complexes, Cp'3Ln, 1, (Cp' = C5H4SiMe3) and [K(2.2.2-cryptand)][Cp'3Ln], 2, respectively, have been synthesized for the six lanthanides traditionally known in +2 oxidation states, i.e., Ln = Eu, Yb, Sm, Tm, Dy, and Nd, to allow direct structural and spectroscopic comparison with the recently discovered Ln(2+) ions of Ln = Pr, Gd, Tb, Ho, Y, Er, and Lu in 2. 2-La and 2-Ce were also prepared to allow the first comparison of all the lanthanides in the same coordination environment in both +2 and +3 oxidation states. 2-La and 2-Ce show the same unusual structural feature of the recently discovered +2 complexes, that the Ln-(Cp' ring centroid) distances are only about 0.03 longer than in the +3 analogs, 1. The Eu, Yb, Sm, Tm, Dy, and Nd complexes were expected to show much larger differences, but this was observed for only four of these traditional six lanthanides. 2-Dy and 2-Nd are like the new nine ions in this tris(cyclopentadienyl) coordination geometry. A DFT-based model explains the results and shows that a 4f?(n)5d(1) electron configuration is appropriate not only for the nine recently discovered Ln(2+) ions in 2 but also for Dy(2+) and Nd(2+), which traditionally have 4f?(n+1) electron configurations like Eu(2+), Yb(2+), Sm(2+), and Tm(2+). These results indicate that the ground state of a lanthanide ion in a molecule can be changed by the ligand set, a previously unknown option with these metals due to the limited radial extension of the 4f orbitals. PMID:25541886

Fieser, Megan E; MacDonald, Matthew R; Krull, Brandon T; Bates, Jefferson E; Ziller, Joseph W; Furche, Filipp; Evans, William J

2015-01-14

222

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

E-print Network

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

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

2011-06-10

223

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

SciTech Connect

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.

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. [Nuclear Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhan Nagar, Kolkata-700064 (India); Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Mumbai-400005 (India); Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Department of Physics, Behala College, Parnasree, Kolkata-700060 (India)

2011-06-15

224

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

SciTech Connect

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.

Zhang, Jia, E-mail: zhangjia@hytc.edu.cn; Chen, Guibin [School of Physics and Electronic Electrical Engineering, Huaiyin Normal University, 111 West Chang Jiang Road, Huai'an 223001 (China); Wang, Yuhua [Department of Material Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Huang, Yan [Laboratory of Beijing Synchrotron Radiation, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

2014-03-07

225

Magnetic ordering at anomalously high temperatures in Dy at extreme pressures  

NASA Astrophysics Data System (ADS)

In an attempt to destabilize the magnetic state of the heavy lanthanide Dy, extreme pressures were applied in an electrical resistivity measurement to 157 GPa over the temperature range 1.3-295 K. The magnetic ordering temperature To and spin-disorder resistance Rsd of Dy, as well as the superconducting pair-breaking effect ? Tc in Y(1 at.% Dy), are found to track each other in a highly nonmonotonic fashion as a function of pressure. Above 73 GPa, the critical pressure for a 6% volume collapse in Dy, all three quantities increase sharply (d To/d P ?5.3 K/GPa), To appearing to rise above ambient temperature for P >107 GPa. In contrast, To and ? Tc for Gd and Y(0.5 at.% Gd), respectively, show no such sharp increase with pressure (d To/d P ?0.73 K/GPa). Taken together, these results suggest that extreme pressure transports Dy into an unconventional magnetic state with an anomalously high magnetic ordering temperature.

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

2015-01-01

226

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

PubMed

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

Hnninen, Mikko M; Mota, Antonio J; Aravena, Daniel; Ruiz, Eliseo; Sillanp, Reijo; Camn, Agustn; Evangelisti, Marco; Colacio, Enrique

2014-07-01

227

Luminescence properties of barium--gadolinium-titanate ceramics doped with rare-earth ions (Eu3+ and Tb3+).  

PubMed

Barium-gadolinium-titanate (BaGd2 Ti4 O12) powder ceramics doped with rare-earth ions (Eu(3+) and Tb(3+)) were synthesized by a solid-state reaction method. From the X-ray diffraction spectrum, it was observed that Eu(3+) and Tb(3+):BaGd2 Ti4 O12 powder ceramics are crystallized in the form of an orthorhombic structure. Scanning electron microscopy image shows that the particles are agglomerated and the particle size is about 200 nm. Eu(3+) - and Tb(3+) -doped BaGd2 Ti4 O12 powder ceramics were examined by energy dispersive X-ray analysis, Fourier transform infrared spectroscopy, photoluminescence and thermoluminescence (TL) spectra. Emission spectra of Eu(3+)-doped BaGd2 Ti4 O12 powder ceramics showed bright red emission at 613 nm ((5)D0 ?(7)F2) with an excitation wavelength ?(exci) ?= 408 nm ((7)F0 ? (5)D3) and Tb(3+):BaGd2 Ti4 O12 ceramic powder has shown green emission at 534 nm ((5)D4 ? (7)F5) with an excitation wavelength ?(exci) ?= 331 nm (((7)F6 ? (5)D1). TL spectra show that Eu(3+) and Tb(3+) ions affect TL sensitivity. PMID:24616270

Hemasundara Raju, S; Muni Sudhakar, B; Sudhakar Reddy, B; Dhoble, S J; Thyagarajan, K; Nageswara Raju, C

2014-11-01

228

Role of spin-lattice coupling in the ultrafast demagnetization of Gd1-xTbx alloys  

NASA Astrophysics Data System (ADS)

After excitation by femtosecond laser pulses, Gd and Tb exhibit ultrafast demagnetization in two steps, with the time constant of the second step linked to the coupling strength of the 4f magnetic moments to the lattice. In time-resolved magneto-optical Kerr effect measurements of Gd1-xTbx alloys, we observe a decrease in this time constant from 33 to 9 ps with Tb content x increasing from 0 to 0.7. We explain this behavior by the stronger spin-lattice coupling of Tb compared to Gd, which increases the effective spin-lattice coupling in Gd1-xTbx with x. In contrast, the faster time constant of the first demagnetization step exhibits no dependence on x. Additional time- and element-resolved x-ray magnetic circular dichroism measurements show a two-step demagnetization of Gd and Tb in Gd0.6Tb0.4 with an equivalent time scale of the second step but a different magnitude of demagnetization which persists for 15 ps. We explain this by an increased coupling of the Gd 4f magnetic moments to the lattice compared to pure Gd, via interatomic exchange coupling to the neighboring Tb 4f moments mediated by 5d electrons, which has limited efficiency and allows an estimation of a characteristic time scale of the interatomic exchange coupling. We assign the first demagnetization step to the dynamics of the laser-excited 5d electrons, while the second demagnetization step is dominated by the strength of spin-lattice coupling of the 4f electrons.

Eschenlohr, A.; Sultan, M.; Melnikov, A.; Bergeard, N.; Wieczorek, J.; Kachel, T.; Stamm, C.; Bovensiepen, U.

2014-06-01

229

Affordable TB treatments. South.  

PubMed

This short article reports the proceedings of a session of the World Health Organization (WHO) on tuberculosis (TB) prevention and management. 15 million persons are infected with both TB and HIV; 11 million of these people are in sub-Saharan Africa. Current TB management relies on finding cases and treating them. According to Paul Nunn of WHO, the role of preventive therapy is unclear. Jensa Bell, of Mt. Sinai Hospital in New York, reported on the cost effectiveness of prevention with isoniazid (INH) in sub-Saharan Africa. Direct medical costs of the drug for 6 months are CHF171/year of life saved. When social costs of TB and prevention of secondary cases are included, INH prophylaxis saves money; initial investment is CHF34.50/person treated, while cost averted is CHF36.24/person treated. Mary Mulindwa, of the Joint Clinical Research Centre in Kampala, Uganda, studied reasons for nonadherence to TB preventive regimens in a clinical trial. Major reasons included the following: 1) transport difficulties; 2) caring for a sick family member; 3) change of address without informing the home visitor; and 4) stigma of being seen with a health worker. Richard Chaisson, of the CP-CRA004/ACTG177 study group, reported results from a trial comparing prevention with INH for 12 months to rifampin plus pyrazinamide (R/P) for 2 months in 1600 tuberculin-positive, HIV-positive people without active disease in the US, Mexico, Brazil, and Haiti. "Effective therapy" with INH was equal to at least 6 months of continuous adherence; 67% of patients met this standard. 80% of R/P patients were adherent. Over 3 years, there were 26 confirmed cases of TB in the INH group and 19 in the R/P group; these results are equivalent. However, Chaisson noted that the cost and feasibility of R/P treatment in resource-poor settings should be considered. PMID:12222196

1998-07-01

230

Magnetic order and electromagnon excitations in DyMnO3 studied by neutron scattering experiments  

NASA Astrophysics Data System (ADS)

Magnetic order and excitations in multiferroic DyMnO3 were studied by neutron scattering experiments using a single crystal prepared with an enriched 162Dy isotope. The ordering of Mn moments exhibits pronounced hysteresis arising from the interplay between Mn and Dy magnetism, which has a strong impact on the ferroelectric polarization. The magnon dispersion resembles that reported for TbMnO3. We identify the excitations at the magnetic zone center and near the zone boundary in the b direction, which can possess electromagnon character. The lowest frequency of the zone-center magnons is in good agreement with a signal in a recent optical measurement, so this mode can be identified as the electromagnon coupled by the same Dzyaloshinskii-Moriya interaction as the static multiferroic phase.

Finger, T.; Binder, K.; Sidis, Y.; Maljuk, A.; Argyriou, D. N.; Braden, M.

2014-12-01

231

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

SciTech Connect

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

Matselko, Oksana; Pukas, Svitlana; Lutsyshyn, Yuriy [Department of Inorganic Chemistry, Ivan Franko National University of Lviv, Kyryla i Mefodiya St. 6, 79005 Lviv (Ukraine)] [Department of Inorganic Chemistry, Ivan Franko National University of Lviv, Kyryla i Mefodiya St. 6, 79005 Lviv (Ukraine); Gladyshevskii, Roman, E-mail: Roman.Gladyshevskii@franko.lviv.ua [Department of Inorganic Chemistry, Ivan Franko National University of Lviv, Kyryla i Mefodiya St. 6, 79005 Lviv (Ukraine)] [Department of Inorganic Chemistry, Ivan Franko National University of Lviv, Kyryla i Mefodiya St. 6, 79005 Lviv (Ukraine); Kaczorowski, Dariusz [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw (Poland)] [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw (Poland)

2013-02-15

232

Tuberculosis (TB): Treatment  

MedlinePLUS

... biggest danger in TB treatment is that the patient will not take antibiotics on schedule. This gives the bacteria the opportunity to develop resistance to the drugs, rebound, and become much more difficult to treat. Therefore, it is crucial to ... a Patient Make an Appointment Ask a Question Learn About ...

233

Metastable RFe7 compounds (R=rare earths) and their nitrides with TbCu7 structure  

NASA Astrophysics Data System (ADS)

RFe7 compounds with the TbCu7 structure have been synthesized by annealing of mechanically alloyed powders. The lattice constants a and c decrease with increasing atomic number of the rare earths except for Ce which has a different valence state. Introduction of nitrogen interstitial atoms into the structure results in a 6.0% volume expansion. In addition, nitriding gives rise to a dramatic enhancement of the magnetic properties of the compounds. Curie temperatures are increased by 300 C upon nitriding. RFe7 nitrides with R=Sm, Tb, Dy, and Ho have high coercivities. A substantial enhancement in the magnetic remanence for the RFe7 nitrides with R=Tb, Dy, and Ho is attributed to the magnetic exchange coupling between grains of nanocrystalline structure in the powders.

Mao, O.; Yang, J.; Altounian, Z.; Strm-Olsen, J. O.

1996-04-01

234

Ternary aluminides R0.67Ni2Al6 (R=Sc, Y, Gd-Lu) with partly disordered structures  

NASA Astrophysics Data System (ADS)

Ten rare-earth nickel aluminides R0.67Ni2Al6 (R=Sc, Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were synthesized by arc melting and their crystal structures studied by X-ray powder diffraction. They crystallize in the hexagonal structure type Yb0.67Ni2Al6: Pearson symbol hP11-2.33, space group P-6m2, a=4.18904(2), c=9.09816(6) , which can be decomposed into three kinds of layer. The sequence of layers along [001] is Yb0.67Al-NiAl2-Al-NiAl2, but stacking faults appear due to relative shifts of consecutive Yb0.67Al layers containing two rare-earth metal atoms for one Al-atom triangle. An ordered superstructure is the type ErNi3Al9 (Pearson symbol hR78, space group R32, a=?{3}a0, c=3c0), refined on single crystals. The physical properties of the R0.67Ni2Al6 (R=Tb, Er, Tm, Yb, and Lu) compounds were determined by means of magnetic and electrical transport measurements. All these materials but Lu0.67Ni2Al6 exhibit Curie-Weiss paramagnetic behavior due to the trivalent R ions, and order magnetically at low temperatures. They show good metallic conductivity. The Yb-containing compound is a dense Kondo system with distinct features in the paramagnetic state of the interplay between Kondo and crystalline electric field interactions.

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

2013-02-01

235

LiDy(PO(3))(4).  

PubMed

Single crystals of lithium dysprosium polyphosphate, LiDy(PO(3))(4), were prepared by the flux method. The atomic arrangement is built up by infinite (PO(3))(n) chains extending along the b axis. Dy(3+) and Li(+) cations alternate in the middle of four such chains, with Dy?Li distances of 3.54?(1) and 3.48?(1)?. The DyO(8) dodeca-hedra and LiO(4) tetra-hedra deviate significantly from the ideal geometry. Both Dy and Li occupy special positions (Wyckoff position 4e, site symmetry 2). PMID:21202729

Chehimi-Moumen, Fathia; Frid, Mokhtar

2008-01-01

236

Gadolinium ytterbium trifluoride, Gd0.81Yb0.19F3.  

PubMed

A new gadolinium ytterbium trifluoride has been grown for the first time by the Czochralski technique. Although GdF(3) and YbF(3) both present a high-temperature phase transition, the mixed compound Gd(0.81)Yb(0.19)F(3) maintains its crystallographic structure upon cooling to room temperature. Taking into account that both Gd(3+) and Yb(3+) ions are distributed randomly on a single site (Wyckoff position 4c), this is attributed to a mean cationic radius coincident with that of the Tb(3+) ion, so that the stability of the crystal structure resembles that of TbF(3). The grown crystal melts noncongruently at ?1413?K, it is transparent and colourless, and it has a high density. PMID:21285491

Vasyliev, Valentyn; Villora, Encarnacion G; Nakamura, Masaru; Sato, Akira; Shimamura, Kiyoshi

2011-02-01

237

Oriented electrophoretic deposition of GdOCl nanoplatelets.  

PubMed

Electrophoretic deposition has emerged as a versatile and precisely tunable approach for the rapid deposition of conformal thin films of colloidal nanocrystals. The electrophoretic deposition of phosphor particles has assumed special significance in recent years as a commercially viable means toward the fabrication of large-area, ultrathin high-resolution emissive display screens. Here, we demonstrate that the anisotropic shape of colloidal ligand-passivated GdOCl nanoplatelets enables their assembly with remarkable substrate alignment and a high packing density upon electrophoretic deposition. GdOCl nanocrystals are promising candidates for phosphor applications given their low maximum phonon cutoff energy, robust chemical stability over prolonged periods of operation, and ability to promote efficacious phonon energy transfer to dopant ions. Potentiostatic deposition of GdOCl nanoplatelets from cyclohexane dispersions allows the deposition of individual nanoplatelets with their basal planes parallel to the electrode surface. Tuning the applied voltage and solution concentration allows control of film thickness, ranging up to several tens of micrometers. The high degree of particle alignment is attributed to anisotropic charge distribution and entrainment within electroosmotic flows established in the vicinity of the electrode surface. The oriented high-particle-density GdOCl nanoplatelet thin films are possible candidates for phosphor applications, which is illustrated by the green emission from a Tb-doped GdOCl thin film on indium tin oxide (ITO)-coated glass. PMID:22963367

Kort, Kenneth R; Banerjee, Sarbajit

2013-02-14

238

Rare earth (Sm3+ and Dy3+)-doped gadolinium oxide nanomaterials for luminescence thermometry  

NASA Astrophysics Data System (ADS)

The possibility of using Sm3+- and Dy3+-doped Gd2O3 nanopowders as thermographic phosphor materials was studied. Both samples were synthesized by a combustion method. The crystalline structure of synthesized samples was confirmed by x-ray diffraction measurements. Photoluminescence measurements were recorded in the temperature range from 298 to 773 K. The photoluminescence spectrum of Sm3+ showed peaks that originate from 4G5/2 ? 6HJ transitions, while in the case of Dy3+ 4F7/2 ? 6HJ transitions were observed. The fluorescence intensity ratio of the prepared nanomaterials was studied as a function of temperature using the 4G5/2 ? 6H5/2 and 4G5/2 ? 6H7/2 transitions of Sm3+ ions and the 4F7/2 ? 6H13/2 and 4F7/2 ? 6H15/2 transitions of Dy3+ ions. Both doped Gd2O3 samples proved to have good potential for the development of thermographic phosphors. The maximum sensitivity was approximately 1.744 10-3 K-1 for the sample with 1 mol% Sm3+ at 701 K and 2.48 10-3 K-1 for the sample with 1 mol% Dy3+ at 773 K. The lifetime measurements were recorded in the same temperature region for the 606 and 572 nm lines of samarium and dysprosium, respectively. The lifetime at room temperature was found to be about 0.395 ms for Sm3+ and 0.123 ms for Dy3+ and it decreased as the temperature increased.

Al-Juboori, Ayad Zwayen M.

2013-11-01

239

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

SciTech Connect

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

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

1999-07-02

240

Radiative lifetimes of Tb  

SciTech Connect

Radiative lifetimes measured by time-resolved laser-induced fluorescence are reported for 40 odd-parity levels and 36 even-parity levels of singly ionized terbium. The odd-parity levels range in energy from 29000 to 40000 cm{minus}1 and those of even-parity from 21000 to 37000 cm{minus}1. These lifetimes, with one exception, are accurate to {+-}5%. They will provide an absolute scale for accurate atomic-transition probabilities in Tb II (the second spectrum of terbium). {copyright} 2001 Optical Society of America

Den Hartog, E. A.; Fedchak, J. A.; Lawler, J. E.

2001-06-01

241

CRITICAL BEHAVIOR OF ACOUSTICAL WAVES IN FERROELECTRIC-FERROELASTIC PHASE OF Tb2(MoO4)3  

E-print Network

. - Gadolinium molybdate Gd2(MO04). (GMO) and terbium molybdate Tb2(Mo04)3 (TMO) under- goes a ,structural phase]. Ultrasonic measurements [5, 6] and Brillouin diffusion experiments [7, 8] have been carried out on GMO with the Centre National de la Recherche Scienti- fique. for a and c directions in a GMO monodomain : a coupling

Paris-Sud XI, Université de

242

Lifetime Measurements in ^162Dy  

NASA Astrophysics Data System (ADS)

There has been great debate over the existence of low-lying vibrational excitations in deformed nuclei -- The original picture presented by Bohr & Mottelson was one of collective vibrations superimposed on a deformed ground state shape, however empirically, it has been difficult to determine if the observed excitations are indeed vibrational in nature or excitations built on two-single particle states. One signature of collectivity is the extraction of absolute B(E2) transition probabilities from measured lifetimes. The complete spectroscopy of ^162Dy was recently published up to 4 MeV [1], we have measured the lifetimes of several levels in the ^162Dy nucleus using the GRID technique at The Institut Laue-Langevin in Grenoble, France. The Dy target was inserted into the core of a 60 MW high flux beam reactor and the line width was measured using a double flat crystal spectrometer (GAMS4) of perfect Silicon crystals. The GRID technique allows measurements of lifetimes from a few picoseconds and lower. Preliminary lifetime measurements will be presented.[4pt][1] A. Aprahamian, et al., Nucl. Phys. A 764 42 (2006). This work was supported by the NSF under contract number PHY07-58100.

Lesher, S. R.; Aprahamian, A.; de Haan, R. C.; Brner, H. G.; Jentschel, M.; Warner, D. D.; Casten, R. F.

2010-11-01

243

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

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}.

Tuncel, Selcan [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster, Corrensstrasse 30, D-48149 Muenster (Germany); Roquefere, Jean Gabriel; Stan, Cristina [CNRS, Universite de Bordeaux, ICMCB, 87 Avenue du Docteur Albert Schweitzer, F-33608 Pessac Cedex (France); Bobet, Jean-Louis [CNRS, Universite de Bordeaux, ICMCB, 87 Avenue du Docteur Albert Schweitzer, F-33608 Pessac Cedex (France)], E-mail: bobet@icmcb-bordeaux.cnrs.fr; Chevalier, Bernard [CNRS, Universite de Bordeaux, ICMCB, 87 Avenue du Docteur Albert Schweitzer, F-33608 Pessac Cedex (France)], E-mail: chevalie@icmcb-bordeaux.cnrs.fr; Gaudin, Etienne [CNRS, Universite de Bordeaux, ICMCB, 87 Avenue du Docteur Albert Schweitzer, F-33608 Pessac Cedex (France); Hoffmann, Rolf-Dieter; Rodewald, Ute Ch [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster, Corrensstrasse 30, D-48149 Muenster (Germany); Poettgen, Rainer [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster, Corrensstrasse 30, D-48149 Muenster (Germany)], E-mail: pottgen@uni-muenster.de

2009-02-15

244

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)

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) , b=8.564(2) , c=14.938(3) , ?=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) 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.

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

2006-12-01

245

TB vaccines for the World.  

PubMed

In September 2003, Montreal hosted the first international conference on "TB Vaccines for the World". The timing of the conference was prescient. Two major contracts for screening TB vaccines, the NIH vaccine screening contract and the European Union Fifth Framework TB Vaccine Cluster were coming to an end as was a major 5 year international initiative to develop vaccines against bovine tuberculosis. For the first time the TB vaccine community was getting a glimpse of the most promising vaccine candidates identified using a number of different animal models. Moreover, the first Phase I human trial of a new vaccine for TB based on boosting BCG with an attenuated vaccinia virus expressing Ag85A of M. tuberculosis, MVA85A, had just begun. In addition, the Aeras Global TB Vaccine Foundation had just been launched to apply an industrial pipeline approach to drive vaccine candidates through to clinical trials. The aim of this special edition of Tuberculosis is to encapsulate this defining moment in the development of TB vaccines so that it may be used it as a yardstick against which future progress may be measured. This article provides an overview of the scope of this task. PMID:15687020

Glyn Hewinson, R

2005-01-01

246

Difference Between Latent TB Infection and Active TB Disease  

MedlinePLUS

... a person with infectious TB coughs or sneezes, droplet nuclei containing M. tuberculosis are expelled into the air. If another person inhales air containing these droplet nuclei, he or she may become infected. However, ...

247

HIV-Associated TB: Facts 2013  

MedlinePLUS

... operational problems and giving demand-driven support to countries and communities. WHO hosts the Stop TB Partnership secretariat as well as providing the staffed secretariat for the TB/HIV Working Group of the Stop TB ... to high burden countries to scale-up implementation of TB/HIV collaborative ...

248

Ternary Dy-Er-Al magnetic refrigerants  

DOEpatents

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.

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

1995-07-25

249

Ternary Dy-Er-Al magnetic refrigerants  

DOEpatents

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.

Gschneidner, Jr., Karl A. (Ames, IA); Takeya, Hiroyuki (Ibaraki, JP)

1995-07-25

250

Lanthanide 4f-level location in AVO(4):Ln(3+) (A = La, Gd, Lu) crystals.  

PubMed

The spectral properties of LaVO(4), GdVO(4) and LuVO(4) crystals doped with Ce(3+), Pr(3+), Eu(3+) or Tb(3+) have been investigated in order to determine the position of the energy levels relative to the valence and conduction bands of the hosts along the trivalent and divalent lanthanide series. Pr(3+) and Tb(3+) ground state levels are positioned based on the electron transfer energy from those states to the conduction band, the so-called intervalence charge transfer (IVCT). This approach is compared with an alternative model that is based on electron transfer from the valence band to a lanthanide. PMID:21693921

Krumpel, Andreas H; van der Kolk, Erik; Cavalli, Enrico; Boutinaud, Philippe; Bettinelli, Marco; Dorenbos, Pieter

2009-03-18

251

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

PubMed

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 during the radiopharmaceutical administration. PMID:15388114

Ferro-Flores, G; Hernndez-Oviedo, O; Arteaga de Murphy, C; Tendilla, J I; Monroy-Guzmn, F; Pedraza-Lpez, M; Aldama-Alvarado, K

2004-12-01

252

Simulation of the magnetocaloric effect in Tb nanofilms  

NASA Astrophysics Data System (ADS)

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 TC = 219 K to TN = 231 K, for external fields of the order of 1 kOe. We find that for strong fields, H = 50 kOe, the adiabatic temperature change ?T near the Nel 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.

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

2014-03-01

253

Simulation of the magnetocaloric effect in Tb nanofilms  

SciTech Connect

Rare-earth (RE) metals have different magnetic structures resulting from the competition between the crystal-field and exchange interactions. When a magnetic field is applied it creates a third interaction and the magnetic structures are more complicated. In thin films, it is expected that even the magnetic arrangement itself can be strongly modified. Rare-earth helimagnets such as Terbium (Tb), Holmium (Ho) and Dysprosium (Dy) represent the best candidates to evidence such finite-size effects. This finite-size effect is caused by the reduced number of atoms in the direction perpendicular to the film plane that leads to a decrease of the total magnetic exchange energy. We report this contribution to the investigation of magnetocaloric effect (MCE) of thin Terbium films in the helimagnetic temperature range, from T{sub C} = 219 K to T{sub N} = 231 K, for external fields of the order of 1 kOe. We find that for strong fields, H = 50 kOe, the adiabatic temperature change ?T near the Nel 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.

Anselmo, Dory Hlio A. L., E-mail: doryh@dfte.ufrn.br [Departamento de Fsica Terica e Experimental (DFTE), Universidade Federal do Rio Grande do Norte (UFRN), Natal-RN (Brazil); Mello, Vamberto D. [Departamento de Fsica,Universidade do Estado do Rio Grande do Norte (UERN), Mossor-RN (Brazil); Vasconcelos, Manoel S. [Escola de Cincia e Tecnologia (ECT), Universidade Federal do Rio Grande do Norte (UFRN), Natal-RN (Brazil)

2014-03-31

254

Gd Transition Probabilities and Abundances  

E-print Network

Radiative lifetimes, accurate to +/- 5%, have been measured for 49 even-parity and 14 odd-parity levels of Gd II using laser-induced fluorescence. The lifetimes are combined with branching fractions measured using Fourier transform spectrometry to determine transition probabilities for 611 lines of Gd II. This work is the largest-scale laboratory study to date of Gd II transition probabilities and the first using a high performance Fourier transform spectrometer. This improved data set has been used to determine a new solar photospheric Gd abundance, log epsilon = 1.11 +/- 0.03. Revised Gd abundances have also been derived for the r-process-rich metal-poor giant stars CS 22892-052, BD+17 3248, and HD 115444. The resulting Gd/Eu abundance ratios are in very good agreement with the solar-system r-process ratio. We have employed the increasingly accurate stellar abundance determinations, resulting in large part from the more precise laboratory atomic data, to predict directly the Solar System r-process elemental abundances for Gd, Sm, Ho and Nd. Our analysis of the stellar data suggests slightly higher recommended values for the r-process contribution and total Solar System values, consistent with the photospheric determinations, for the elements for Gd, Sm, and Ho.

E. A. Den Hartog; J. E. Lawler; C. Sneden; J. J. Cowan

2006-09-18

255

TB in Correctional Facilities Is a Public Health Concern  

MedlinePLUS

... CDC Features TB in Correctional Facilities is a Public Health Concern Share Compartir Diagnosing and treating TB in ... the community with untreated TB present a serious public health concern. Figure 1 (larger view). TB Control in ...

256

Is TB in Your Curriculum?  

ERIC Educational Resources Information Center

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)

Kerr, Joanne; Elwell, Jack

2002-01-01

257

Staying on Track with TB Medicine  

MedlinePLUS

Staying on Medicine Track with TB TUBERCULOSIS 2 Whats Inside: Read this brochure to learn about TB and what you can do to get healthy. Put it in a ... department at __________________________ or visit the CDC Division of Tuberculosis Elimination website at http://www.cdc.gov/tb ...

258

Activation cross-sections of deuteron induced reactions on (nat)Gd up to 50 MeV.  

PubMed

Activation cross-sections are presented for the first time for (nat)Gd(d,xn)(161,160,156(m+)), (154,154m1,154m2,153,152(m+),151(m+))Tb, (nat)Gd(d,x)(159,153,151)Gd and (nat)Gd(d,x)(156)Eu reactions from their respective thresholds up to 50 MeV. The cross-sections were measured by the stacked-foil irradiation technique and by using high resolution ?-ray spectrometry. The measured values were compared with the results of theoretical models calculated by the computer codes ALICE-D, EMPIRE-D and TALYS (data from TENDL library). Integral yields of the reaction products were deduced from the excitation functions. PMID:24215815

Trknyi, F; Takcs, S; Ditri, F; Csikai, J; Hermanne, A; Ignatyuk, A V

2014-01-01

259

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

SciTech Connect

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 dd 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 ff 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.

Liu, Xiaohua, E-mail: xhliuxhliu@tom.com [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China)] [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Xiang, Wendou; Chen, Fengming; Hu, Zhengfa; Zhang, Wei [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China)] [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China)

2013-02-15

260

Synthesis and luminescence characteristics of Dy3+ ions in silica xerogels doped with Ln2-xDyx(WO4)3  

NASA Astrophysics Data System (ADS)

Lanthanium tungstates (where Ln = La or Gd) doped with dysprosium ion and incorporated into silica xerogel were prepared by the sol-gel process. X-ray diffraction (XRD) and transmission electron microscopy (TEM) methods were used to investigate structural and morphological properties of the obtained materials. Reflectance and emission spectra were measured at room temperature. These materials exhibit strong absorption band in the UV region. Moreover, photoluminescence spectra contain the characteristic emission bands of Dy3+ in the host matrix. In particular, yellow emission at 575 nm (4F-6H) and blue emission at 484 nm (4F-6H) were observed due to the excitation energy transfer from WO42- group to Dy(III) ion upon excitation at ?exc = 240 nm which is the important finding result of this paper. These results are supplemented by the analysis of the luminescence kinetics of Dy(III) ions in the studied materials.

Grobelna, Beata; Synak, Anna; Bojarski, Piotr; Szczodrowski, Karol; Kukli?ski, Benedykt; Raut, Sangram; Gryczy?ski, Ignacy

2013-01-01

261

Lifetime measurements and shape coexistence in {sup 144}Dy  

SciTech Connect

The known level scheme of {sup 144}Dy has been extended and lifetime measurements have been made with the recoil-distance Doppler-shift method. Reduced transition probabilities and deformations have been determined for four low-lying transitions. These states form part of the first observed band crossing, giving information on the change in nuclear deformation resulting from the rearrangement of h{sub 11/2} protons in the nucleus. Two bands built upon excited 10{sup +} states have been assigned pi(h{sub 11/2}){sup 2} prolate and nu(h{sub 11/2}){sup -2} oblate configurations with tau=12(2)ps and 0.01Gd.

Procter, M. G.; Cullen, D. M.; Niclasen, B.; Mason, P. J. R.; Rigby, S. V.; Dare, J. A.; Lumley, N. M. [Schuster Laboratory, University of Manchester, Manchester M13 9PL (United Kingdom); Scholey, C.; Greenlees, P. T.; Jakobsson, U.; Jones, P. M.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Nyman, M.; Puurunen, A.; Rahkila, P.; Ruotsalainen, P.; Saren, J. [Department of Physics, University of Jyvaeskylae, FIN-40014 Jyvaeskylae (Finland)

2010-05-15

262

Studies on sintered permanent magnets RE-Fe-M-Co-B Nd, Pr, Dy, Tb; M =  

E-print Network

RE-(Fe, Co, M) aux joints de grains est responsable de l'inhibition des corrosions acide et of these alloys was responsible for inhibition of the corrosion in acid solution and in atmospheric environment propriétés magnétiques et le comportement à la corrosion des aimants frittés RE16Fe71 - xMxCo5B8 ont été

Boyer, Edmond

263

Two-dimensional coordination polymers constructed by [Ni(II)Ln(III)] nodes and [W(IV)(bpy)(CN)6]2- spacers: a network of [Ni(II)Dy(III)] single molecule magnets.  

PubMed

Three isomorphous two-dimensional (2D) coordination polymers of general formula {[Ni(II)(valpn)Ln(III)(NO3)(H2O)(?-NC)4W(IV)(bipy)(CN)2]xH2OyCH3CN}n have been synthesized by reacting Ph4P[W(V)(CN)6(bipy)] with the heterodinuclear [Ni(II)Ln(III)(valpn)(O2NO)3] complexes [H2valpn = 1,3-propanediyl-bis(2-iminomethylene-6-methoxyphenol), bipy = 2,2'-bipyridine, and Ln = Gd (1), Dy (2), and Tb (3) with x = 2 (1), 3.9 (2), and 3.35 (3) and y = 2.50 (1), 2 (2), and 1.8 (3)]. Their crystal structures consist of [Ni(II)Ln(III)] 3d-4f nodes which are connected by [W(IV)(bipy)(CN)6](2-) diamagnetic linkers resulting from the reduction of W(V) to W(IV) during the reaction process. The Ni(II) and Ln(III) ions occupy the inner and outer coordination sites of the dideprotonated valpn ligand, respectively, and they are doubly bridged by the phenoxo oxygen atoms of such a ligand. The value of Ni(II)Ln(III) separation through this bridge is 3.4919(10) (1), 3.4760(10) (2), and 3.4799(9) (3) , and those of the angles at the bridgehead phenoxo atoms are 106.6(2) and 107.3(2) (1), 106.9(2), and 107.8(2) (2) and 106.5(2)-106.8(2) (3). Each W(IV) is eight-coordinated with a bidentate bipy molecule and six cyanide-carbon atoms building a somewhat distorted square antiprism environment. The rare-earth cations are nine-coordinated, the donor atoms describing a monocapped square antiprism for 1 and 3 and a tricapped trigonal prism for 2. Magnetic susceptibility measurements in the temperature range 1.9-300 K show the occurrence of ferromagnetic interactions between the Ni(II) and Ln(III) ions in 1-3. Frequency-dependent alternating susceptibility signals were observed for the Dy(III) derivative below 8.0 K under an applied dc field of 2500 G indicating the presence of slow magnetic relaxation with values of the pre-exponential factor (?0) and energy barrier (E(#)) of ca. 5.7 10(-8) s and 15.9 cm(-1), respectively. Complex 2 constitutes the first example of a 2D 3d-4f heterobimetallic single molecule magnet (SMM). PMID:24067093

Alexandru, Maria-Gabriela; Visinescu, Diana; Shova, Sergiu; Lloret, Francesc; Julve, Miguel; Andruh, Marius

2013-10-01

264

Production of 166Ho through 164Dy(n, gamma)165Dy(n, gamma)166Dy(beta-)166Ho and separation of 166Ho.  

PubMed

After irradiation with thermal neutrons 164Dy produces 166Ho through the nuclear reaction: 164Dy(n, gamma) 165Dy(n, gamma) 166Dy beta- --> 166Ho. 166Ho has been separated from the bulk dysprosium target with the help of HPLC using Aminex A7 ion exchanger resin and alpha-hydroxyisobutyric acid (alpha-HIBA) as the mobile phase. The separation was quantitative and without any contamination from the dysprosium target. Method has also been developed to produce holmium free of alpha-HIBA ligands. Attempts have been made to produce no-carrier-added recoiled 166Ho and 165Dy in water. PMID:15388104

Lahiri, Susanta; Volkers, Kees J; Wierczinski, Birgit

2004-12-01

265

Electrochemical formation of Dy alloy films in a molten LiCl-KCl-DyCl3 system  

NASA Astrophysics Data System (ADS)

As to the electrochemical formation of Dy-Ni alloy films in a molten LiCl-KCl-DyCl3 system at 700 K, the growth of DyNi2 film and behavior of anodic dissolution of Dy from the formed DyNi2 film were investigated. The DyNi2 films were formed by potentiostatic electrolysis at 0.55, 0.62 and 0.70 V with Ni electrodes. The growth rates of DyNi2 films are higher at less noble potential, i.e., 0.47 8m min-1 at 0.55 V, 0.32 8m min-1 at 0.62 V and 0.14 8m min-1 at 0.70 V. From RBS analysis, it was suggested that the Dy-Ni alloy film was formed for 10 or 30 s during electrodepositing Dy at 0.30 V with a Ni electrode. Moreover, the growth rate of Dy-Ni alloy film was faster than that of Dy-Fe alloy film. Anodic electrolysis of the formed DyNi2 film with thickness of 15 ?m was conducted at 0.90 V, 1.30 V and 1.90 V, respectively. The formed DyNi2 were transformed to other phases, i.e., DyNi3, DyNi5 and Ni, by selective anodic dissolution of Dy. The transformed Ni film was about 10 ?m in thickness and had a porous structure with a pore diameter of 1~2 ?m.

Konishi, H.; Usui, T.; Nohira, T.; Ito, Y.

2009-05-01

266

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

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.

Phillips, M.L.F.; Potter, B.G. Jr.

1995-10-01

267

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

MedlinePLUS

... of Drug-Resistant TB TB Home Page Photo Credit : The photo of Mycobacterium tuberculosis was obtained from ... Prevention , CDC/ Dr. Ray Butler; Janice Carr. Illustration Credit : This illustration is in the public domain. Please ...

268

Sensitisation of Eu(III)- and Tb(III)-based luminescence by Ir(III) units in Ir/lanthanide dyads: evidence for parallel energy-transfer and electron-transfer based mechanisms.  

PubMed

A series of blue-luminescent Ir(III) complexes with a pendant binding site for lanthanide(III) ions has been synthesized and used to prepare Ir(III)/Ln(III) dyads (Ln = Eu, Tb, Gd). Photophysical studies were used to establish mechanisms of Ir?Ln (Ln = Tb, Eu) energy-transfer. In the Ir/Gd dyads, where direct Ir?Gd energy-transfer is not possible, significant quenching of Ir-based luminescence nonetheless occurred; this can be ascribed to photoinduced electron-transfer from the photo-excited Ir unit (*Ir, (3)MLCT/(3)LC excited state) to the pendant pyrazolyl-pyridine site which becomes a good electron-acceptor when coordinated to an electropositive Gd(III) centre. This electron transfer quenches the Ir-based luminescence, leading to formation of a charge-separated {Ir(4+)}?-(pyrazolyl-pyridine)?(-) state, which is short-lived possibly due to fast back electron-transfer (<20 ns). In the Ir/Tb and Ir/Eu dyads this electron-transfer pathway is again operative and leads to sensitisation of Eu-based and Tb-based emission using the energy liberated from the back electron-transfer process. In addition direct Dexter-type Ir?Ln (Ln = Tb, Eu) energy-transfer occurs on a similar timescale, meaning that there are two parallel mechanisms by which excitation energy can be transferred from *Ir to the Eu/Tb centre. Time-resolved luminescence measurements on the sensitised Eu-based emission showed both fast and slow rise-time components, associated with the PET-based and Dexter-based energy-transfer mechanisms respectively. In the Ir/Tb dyads, the Ir?Tb energy-transfer is only just thermodynamically favourable, leading to rapid Tb?Ir thermally-activated back energy-transfer and non-radiative deactivation to an extent that depends on the precise energy gap between the *Ir and Tb-based (5)D4 states. Thus, the sensitised Tb(iii)-based emission is weak and unusually short-lived due to back energy transfer, but nonetheless represents rare examples of Tb(III) sensitisation by a energy donor that could be excited using visible light as opposed to the usually required UV excitation. PMID:24608523

Sykes, Daniel; Cankut, Ahmet J; Ali, Noorshida Mohd; Stephenson, Andrew; Spall, Steven J P; Parker, Simon C; Weinstein, Julia A; Ward, Michael D

2014-05-01

269

Metallic surface electronic state in half-Heusler compounds RPtBi (R= Lu, Dy, Gd)  

NASA Astrophysics Data System (ADS)

Rare-earth platinum bismuth (RPtBi) has been proposed recently as a potential topological insulator. In this paper, we present measurements of the metallic surface electronic structure in three members of this family, using angle-resolved photoemission spectroscopy (ARPES). Our data show clear spin-orbit splitting of the surface bands and the Kramers degeneracy of spins at the ? and M points, which is reproduced nicely with our full-potential linearized augmented plane wave calculation for a surface electronic state. Topologically nontrivial behavior is signified by band inversion in the calculated bulk electronic structures, yet no direct indication of such behavior is detected by ARPES except for a weak Fermi crossing detected in close proximity to the ? point, making the total number of Fermi crossings odd. In the surface band calculation, however, this crossing is explained by a Kramers pair of bands that are very close to each other. The classification of this family of materials as topological insulators remains an open question.

Liu, Chang; Lee, Yongbin; Kondo, Takeshi; Mun, Eun Deok; Caudle, Malinda; Harmon, B. N.; Bud'Ko, Sergey L.; Canfield, Paul C.; Kaminski, Adam

2011-05-01

270

A novel synthesis of phase-pure ultrafine YAG:Tb phosphor with different Tb concentration  

Microsoft Academic Search

Ultrafine luminescent yttrium aluminum garnet (YAG):Tb powders doped with different Tb concentration are prepared by a nitratecitrate solgel combustion process. Single-phase cubic YAG:Tb crystalline is obtained at 800 C by directly crystallizing from amorphous materials as determined by X-ray diffraction (XRD) techniques. The resultant YAG:Tb powders heat-treated at 1000 C are uniform and in good dispersity with particle size of

Jun-ji Zhang; Jin-wei Ning; Xue-jian Liu; Yu-bai Pan; Li-ping Huang

2003-01-01

271

New cloth modeling for designing dyed patterns  

Microsoft Academic Search

We propose a novel cloth modeling method to simulate dyeing techniques. Morimoto et al. [2007] proposed a physics-based dyeing simulation method. To simulate dyeing techniques in conjunction with folded 3D cloth geometries, we developed a natural and intuitive method to generate cloth geometries. This method uses locally applied geometric operations for multiple dyed patterns on a cloth and a Voronoi

Yuki Morimoto; Kenji Ono

2010-01-01

272

Mechanism of amorphous state formation, crystalline structure, and hyperfine interactions in DyMn6-xGe6Fex (0<=x<=6) alloys  

NASA Astrophysics Data System (ADS)

Metallic glass formation is observed in rapidly quenched quaternary DyMn6-xGe6Fex (0?x?6) alloys. The easy formation of amorphous states competes with the nucleation of ternary 1:6:6 rare earth-transition metal-metal compounds DyMn6Ge6 and DyFe6Ge6. The ribbon shaped samples were quenched and investigated by x-ray diffraction, differential scanning calorimetry, and F57e Mssbauer spectrometry. Melt-spun alloys from the series of DyMn6-xGe6Fex with x=0, 2?x?3, and x=6 do not display an amorphous state but a crystalline chemically disordered structure similar to that of TbCu7- or TbFe6Sn6-type (space group P6/mmm). Amorphous samples exhibit two crystallization steps but there is no clear evidence for a glass transition effect in the calorimetric data. The Kissinger analysis was performed to calculate the effective activation energy Ea, which is equal to 34520 kJ/mol for amorphous DyMn5.5Ge6Fe0.5 alloy. Mssbauer spectra at 77 and 300 K consist of either magnetic sextets or quadrupolar doublets for high and low Fe content, respectively. The features reflect the dilution of Fe on crystallographic sites and the subsequent increase in topological and chemical disorder when the Mn content increases. The Miedema's semiempirical model was used to calculate the formation enthalpies of amorphous alloys (?Hform). The calculated values are consistent with experimental results. The present model allows thus to explain the better glass forming ability for the compositions with high Mn content, where ?Hform is the most negative.

?niadecki, Z.; Mielniczuk, B.; Idzikowski, B.; Greneche, J.-M.; Rler, U. K.

2010-10-01

273

Epitaxial growth and characterization of DyP\\/GaAs, DyAs\\/GaAs, and GaAs\\/DyP\\/GaAs heterostructures  

Microsoft Academic Search

There is a significant interest in the area of improving high temperature stable contacts to III-V semiconductors. Two attractive\\u000a material systems that offer promise in this area are dysprosium phosphide\\/gallium arsenide (DyP\\/GaAs) and dysprosium arsenide\\/gallium\\u000a arsenide (DyAs\\/GaAs). Details of epitaxial growth of DyP\\/GaAs and DyAs\\/GaAs by molecular beam epitaxy (MBE), and their characterization\\u000a by x-ray diffraction, transmission electron microscopy, atomic

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

1998-01-01

274

Tuberculosis: Learn the Signs and Symptoms of TB Disease  

MedlinePLUS

... Compartir Tuberculosis (TB) is a disease caused by bacteria that are spread through the air from person ... TB. Tuberculosis (TB) is a disease caused by bacteria that are spread through the air from person ...

275

Growth and characterization of DyP/GaAs and DyAs/GaAs-based heterostructures and superlattices  

NASA Astrophysics Data System (ADS)

Details of the structural and electrical properties of epitaxial DyP/GaAs and DyAs/GaAs is reported. DyP is lattice matched to GaAs, with a room temperature mismatch of less than 0.01%. DyAs, on the other hand, has a mismatch of nearly 2.4%. 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 epilayers, as determined by XRD, TEM, and AFM analysis, were obtained for growth temperatures ranging from 500C to 600C with growth rates between 0.5 and 0.7 ?m/h. The DyP epilayers are n-type with measured electron concentrations of the order of 310 20 to 410 20 cm -3, with room temperature mobilities of 250-300 cm 2/V s, and with a barrier height of 0.75 eV to GaAs. The DyAs epilayers are also n-type with concentration of 110 21 to 210 21 cm -3, with mobilities between 25 and 40 cm 2/V s. DyP is stable in air with no apparent oxidation taking place, even after months of ambient exposure to untreated air.

Lee, P. P.; Hwu, R. J.; Sadwick, L. P.; Balasubramaniam, H.; Kumar, B. R.; Chern, J. H.; Lareau, R. T.

1998-07-01

276

Stability of multiferroicity against Dy/Mn off-stoichiometry in DyMnO{sub 3}  

SciTech Connect

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.

Wang, J. X.; Liu, M. F.; Zhao, Z. Y.; Yan, Z. B.; Liu, J.-M., E-mail: liujm@nju.edu.cn [Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China)

2014-05-07

277

Magnetoresistance in nanostructured Tb/Ti and Tb/Si multilayers  

SciTech Connect

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.

Svalov, A. V.; Kurlyandskaya, G. V. [Dpto. Electricidad y Electronica, Universidad del Pais Vasco (UPV-EHU), 48080 Bilbao (Spain); Ural State University A.M. Gorky, 620083 Ekaterinburg (Russian Federation); Vas'kovskiy, V. O.; Sorokin, A. N. [Ural State University A.M. Gorky, 620083 Ekaterinburg (Russian Federation); Diercks, D. [Center for Advanced Research and Technology, University of North Texas, Denton, Texas 76203-5017 (United States)

2011-01-15

278

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

NASA Astrophysics Data System (ADS)

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 600C with growth rates between 0.5 and 0.7 m/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/Vs, 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/Vs.

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

279

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

PubMed

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

Ferro-Flores, G; Arteaga de Murphy, C; Pedraza-Lpez, M; Monroy-Guzmn, F; Melndez-Alafort, L; Tendilla, J I; Jimnez-Varela, R

2003-04-14

280

Optical properties of crystals doped with Sm3+ or Dy3+ relevant to potential InGaN/GaN laser diode-pumped visible laser operation: A comparative study  

NASA Astrophysics Data System (ADS)

Results of detailed spectroscopic investigation of Sm3+ and Dy3+ ions incorporated in crystal structures of Yal YAl3(BO3)4, LiNbO3, Gd3Ga5O12, Gd2SiO5, Lu2SiO5 and (Gd, Lu)2SiO5 are reported and discussed. The impact of the hosts on transition intensities and excited state relaxation dynamics of incorporated luminescent ions was examined. Distribution of luminescence intensity among spectral bands in terms of luminescence branching ratios was evaluated based on numerical integration of luminescence bands. Intensities of UV and blue absorption bands potentially useful for optical pumping were determined quantitatively in units of absorption cross section. The most intense luminescence bands related to potential laser transitions 4 G 5/2 ? 6 H 7/2 of Sm3+ around 600 nm and 4 F 9/2 ? 6 H 13/2 of Dy3+ around 580 nm were calibrated in units of emission cross section. Evaluated peak values of emission cross section range from 0.43 10-20 cm2 for Sm3+ in (Gd, Lu)2SiO5 to 1.17 10-20 cm2 for Sm3+ in LiNbO3. Those for dysprosium-doped crystals range from 0.63 10-20 cm2 for LiNbO3:Dy3+ to 2.0 10-20 cm2 for Yal YAl3(BO3)4:Dy3+. It follows from these considerations that samarium-doped crystals show promise for laser application owing to the combination of a strong absorption that matches radiation of commercial laser diodes emitting near 405 nm and long luminescence lifetime. Major shortcoming of dysprosium-doped crystals results from a weak intensity of absorption bands available for optical pumping near 450 nm and 385 nm combined with relatively strong self-quenching of luminescence.

Ryba-Romanowski, W.; Strz?p, A.; Lisiecki, R.; Berkowski, M.

2014-05-01

281

Dysprosium ( 165 Dy) hydroxide macroaggregates for radiation synovectomy animal studies  

Microsoft Academic Search

This paper reports the development of a new chemical formulation, Dy-HMA, to utilise the advantages of dysprosium 165 in radiation synovectomy of certain forms of arthritis. Dy-HMA is a sterile suspension of dysprosium hydroxide macroaggregates (approximately 6 mg Dy\\/ml) in saline with the majority of particles in the 35 m range. The absence of ferric hydroxide and a higher concentration

Ashley McLaren; Eric Hetherington; Des Maddalena; Graeme Snowdon

1990-01-01

282

Scheelite-type NaDy(WO4)2  

PubMed Central

The title compound sodium dysprosium(III) bis[tungstate(VI)], NaDy(WO4)2, has been synthesized under high temperature solution growth (HTSG) conditions in air. The compound crystallizes with the scheelite structure and is composed of isolated WO4 tetrahedra ( symmetry) with one set of bond lengths and distorted [(Na/Dy)O8] dodecahedra ( symmetry; occupancy ratio Na:Dy = 1:1) with two sets of bond lengths. PMID:21579906

Zhao, Dan; Li, Feifei; Cheng, Wendan; Zhang, Hao

2010-01-01

283

A comparative study of magnetic behaviors in TbNi{sub 2}, TbMn{sub 2} and TbNi{sub 2}Mn  

SciTech Connect

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? (space group F-43?m), 7.618?, and 7.158? (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.

Wang, J. L., E-mail: jianli@uow.edu.au [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Bragg Institute, ANSTO, Lucas Heights, NSW 2234 (Australia); Md Din, M. F.; Hong, F.; Cheng, Z. X.; Dou, S. X. [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Kennedy, S. J.; Studer, A. J. [Bragg Institute, ANSTO, Lucas Heights, NSW 2234 (Australia); Campbell, S. J. [School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, Canberra, ACT 2600 (Australia); Wu, G. H. [Institute of Physics, Chinese Academy of Science, Beijing 100190 (China)

2014-05-07

284

Tunable luminescence of Dy3+ single-doped and Dy3+/Tm3+ co-doped tungsten borate glasses  

NASA Astrophysics Data System (ADS)

RE3+ (RE3+ = Tm3+, Dy3+) ion single and co-doped tungsten borate glasses for white light emitting diodes (LEDs) were prepared by melt quenching method. Emission and excitation spectra of the glasses were measured. The color of luminescence can be tuned by changing the composition of glass matrix or the concentrations of Tm3+ and Dy3+ ions. White light emission can be achieved from 0.5Dy3+ single-doped 15WO3-25La2O3-60B2O3 and 0.4Tm3+/1.5Dy3+ co-doped 50WO3-25La2O3-25B2O3 glasses. In addition, energy transfers between Tm3+ and Dy3+ were also analyzed. The Dy3+/Tm3+ co-doped tungsten borate glasses may be potential candidates for white LED application.

Hu, J.; Gong, X. H.; Chen, Y. J.; Huang, J. H.; Lin, Y. F.; Luo, Z. D.; Huang, Y. D.

2014-12-01

285

Synthesis structural and luminescence analysis of NaGd1-XTbx(WO4)2 solid solution for white LED application  

NASA Astrophysics Data System (ADS)

NaGd1-xTbx(WO4)2 (Tb:NGW) green phosphor were synthesised by high temperature solid state reaction. Synthesised powders were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and spectroflorimeter analysis. The formation of NGW scheelite structure was conformed by XRD. FE-SEM images clearly show the surface morphology of synthesized powder. From excitation spectrum, the charge transfer band (CTB) of O-W elucidated at 270 nm and emission spectrum has shown green emission at 545 nm under 270 nm (UV light) excitation. The optimum dopant concentration of Tb has been found to be 15 at%.

Durairajan, A.; Thangaraju, D.; Balaji, D.; Babu, S. Moorthy

2013-02-01

286

Crystal and magnetic structure of the R15Si9C compounds (R = Ho, Er, Tb)  

NASA Astrophysics Data System (ADS)

The synthesis of the new compounds R15Si9C with R = Sm, Gd-Er, Y and R15Ge9C with R = Ce, Pr and Nd has been recently reported; these compounds crystallize in the hexagonal La15Ge9Fe structure type, hP50-P63mc, Z = 2 (ordered superstructure of La5Ge3 (Mn5Si3-type, hP 16-P63/mcm, Z = 2)). Here we report the results of a neutron diffraction investigation that we have performed to study the crystal and magnetic structures of the R15Si9C compounds with R = Tb, Ho and Er. All three compounds see the establishment of commensurate magnetic order with a predominantly ferromagnetic interaction. Details of mixed antiferro-ferromagnetic spin arrangements (? = [000]) (for Tb15Si9C and Ho15Si9C) or of purely ferromagnetic ordering (Er15Si9C), and of their temperature dependence, are given and linked to the different coordination of the four dissimilar rare earth sites. In the Tb and Ho compounds the thermal evolution of the magnetic moment values strongly differs between the different R sites. The position occupied by the principal carbon has been determined (Wyckoff site 2b) and the existence of a second position available for the interstitial carbon (Wyckoff site 2a) has been revealed for R = Ho, Tb. Moreover, in the Tb and Ho compounds the magnetic moment value of the rare earth site R4, surrounding the second interstitial carbon site, is strongly reduced if compared to the value on the other rare earth sites. The magnetic transition temperatures of all three compounds, i.e. TC = 130, 43 and 45 K for Tb15Si9C, Ho15Si9C and Er15Si9C, are remarkably high compared to those of the parent R5Si3 compounds. The magnetic behaviour of the partly filled Tb5Si3C0.25 is reported.

Ritter, C.; Wrubl, F.; Hill, A. H.; Pani, M.; Manfrinetti, P.

2011-07-01

287

Crystal and magnetic structure of the R15Si9C compounds (R = Ho, Er, Tb).  

PubMed

The synthesis of the new compounds R(15)Si(9)C with R = Sm, Gd-Er, Y and R(15)Ge(9)C with R = Ce, Pr and Nd has been recently reported; these compounds crystallize in the hexagonal La(15)Ge(9)Fe structure type, hP50-P6(3)mc, Z = 2 (ordered superstructure of La(5)Ge(3) (Mn(5)Si(3)-type, hP 16-P6(3)/mcm, Z = 2)). Here we report the results of a neutron diffraction investigation that we have performed to study the crystal and magnetic structures of the R(15)Si(9)C compounds with R = Tb, Ho and Er. All three compounds see the establishment of commensurate magnetic order with a predominantly ferromagnetic interaction. Details of mixed antiferro-ferromagnetic spin arrangements (? = [000]) (for Tb(15)Si(9)C and Ho(15)Si(9)C) or of purely ferromagnetic ordering (Er(15)Si(9)C), and of their temperature dependence, are given and linked to the different coordination of the four dissimilar rare earth sites. In the Tb and Ho compounds the thermal evolution of the magnetic moment values strongly differs between the different R sites. The position occupied by the principal carbon has been determined (Wyckoff site 2b) and the existence of a second position available for the interstitial carbon (Wyckoff site 2a) has been revealed for R = Ho, Tb. Moreover, in the Tb and Ho compounds the magnetic moment value of the rare earth site R4, surrounding the second interstitial carbon site, is strongly reduced if compared to the value on the other rare earth sites. The magnetic transition temperatures of all three compounds, i.e. T(C) = 130, 43 and 45K for Tb(15)Si(9)C, Ho(15)Si(9)C and Er(15)Si(9)C, are remarkably high compared to those of the parent R(5)Si(3) compounds. The magnetic behaviour of the partly filled Tb(5)Si(3)C(0.25) is reported. PMID:21715952

Ritter, C; Wrubl, F; Hill, A H; Pani, M; Manfrinetti, P

2011-07-27

288

Immunomodulation by vitamin D: implications for TB  

PubMed Central

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

Chun, Rene F; Adams, John S; Hewison, Martin

2011-01-01

289

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 ...

290

Spectroscopy of 153Gd and 157Gd using the (p ,d ? ) reaction  

NASA Astrophysics Data System (ADS)

Low-spin single quasineutron levels in 153Gd and 157Gd have been studied following the 154Gd(p ,d -? )153Gd and 158Gd(p ,d -? )157Gd reactions. A combined Si telescope and high-purity germanium array was utilized, allowing d -? and d -? -? coincidence measurements. Almost all of the established low-excitation-energy, low-spin structures were confirmed in both 153Gd and 157Gd. Several new levels and numerous new ? rays are observed in both nuclei, particularly for Ex?1 MeV. Residual effects of a neutron subshell closure at N =64 are observed in the form of a large excitation energy gap in the single quasineutron level schemes.

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.; Fallon, P.; Hatarik, R.; Munson, J.; Paschalis, S.; Petri, M.; Phair, L. W.; Ressler, J. J.; Scielzo, N. D.

2014-10-01

291

Spectroscopy of 153Gd and 157Gd using the (p,d ) reaction  

SciTech Connect

Low-spin single quasineutron levels in 153Gd and 157Gd have been studied following the 154Gd(p,d- )153Gd and 158Gd(p,d- )157Gd reactions. A combined Si telescope and high-purity germanium array was utilized, allowing d- and d- - coincidence measurements. Almost all of the established low-excitation-energy, low-spin structures were confirmed in both 153Gd and 157Gd. Several new levels and numerous new rays are observed in both nuclei, particularly for Ex > 1 MeV. Residual effects of a neutron subshell closure at N = 64 are observed in the form of a large excitation energy gap in the single quasineutron level schemes.

Ross, T.J. [University of Richmond; Hughes, R.O. [University of Richmond; Allmond, James M [ORNL; Beausang, C.W. [University of Richmond; Angell, C.T. [Lawrence Berkeley National Laboratory (LBNL); Basunia, M.S. [Lawrence Berkeley National Laboratory (LBNL); Bleuel, D.L. [Lawrence Livermore National Laboratory (LLNL); Burke, J.T. [Lawrence Livermore National Laboratory (LLNL); Casperson, R.J. [Lawrence Livermore National Laboratory (LLNL); Escher, J.E. [Lawrence Livermore National Laboratory (LLNL); Fallon, P. [Lawrence Berkeley National Laboratory (LBNL); Hatarik, R. [Lawrence Berkeley National Laboratory (LBNL); Munson, J. [Lawrence Berkeley National Laboratory (LBNL); Paschalis, S. [Lawrence Berkeley National Laboratory (LBNL); Petri, M. [Lawrence Berkeley National Laboratory (LBNL); Phair, L. [Lawrence Berkeley National Laboratory (LBNL); Ressler, J.J. [Lawrence Livermore National Laboratory (LLNL); Scielzo, N.D. [Lawrence Livermore National Laboratory (LLNL)

2014-01-01

292

Magnetic properties of DyAs and DyP (001) films  

NASA Astrophysics Data System (ADS)

The magnetic properties of two single crystal (001) films of DyP and DyAs have been investigated at temperatures between 2 and 300 K and at fields up to 5 T using SQUID magnetometry. The films were grown epitaxially in the simple NaCl structure on (001) GaAs substrates using molecular beam epitaxy techniques. The phosphide compound exhibits ferromagnetic-like order below 9 K. The ordered phase appears to have 90 spin alignments, a suppressed saturation moment (1.0?B), and a large magnetic anisotropy. In contrast, the arsenide develops an antiferromagnetic-like correlation below 6 K, with a much lower anisotropy and a higher moment (2.8?B) than that of the phosphide. Above the ordering transitions, the two samples exhibit paramagnetism with paramagnetic moments of 4.5 and 7.8?B for the DyP and the DyAs sample, respectively. The observed behavior is consistent with the presence of strong crystal field interactions. Experiments have been proposed to further explore these effects.

Rush, E.; Wu, L.; Tsui, F.; Lee, P. P.; Sadwick, L. P.; Hwu, R. J.

1999-04-01

293

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

SciTech Connect

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.}

Dumesnil, K.; Dufour, C.; Mangin, P.; Marchal, G. [Laboratoire Metallurgie Physique et Science des Materiaux (URA CNRS 155), Universite Henri Poincare-Nancy I, BP 239, 54506 Vandoeuvre les Nancy cedex (France)] [Laboratoire Metallurgie Physique et Science des Materiaux (URA CNRS 155), Universite Henri Poincare-Nancy I, BP 239, 54506 Vandoeuvre les Nancy cedex (France); Hennion, M. [Laboratoire Leon Brillouin, Centre d`Etudes Atomiques de Saclay, 91191 Gif-sur-Yvette cedex (France)] [Laboratoire Leon Brillouin, Centre d`Etudes Atomiques de Saclay, 91191 Gif-sur-Yvette cedex (France)

1996-09-01

294

DyAD: smart routing for networks-on-chip  

Microsoft Academic Search

In this paper, we present and evaluate a novel routing scheme called DyAD which combines the advantages of both deterministic and adaptive routing schemes. More precisely, we envision a new routing technique which judiciously switches between deterministic and adaptive routing based on the network's congestion conditions. The simulation results show the effectiveness of DyAD by comparing it with purely deterministic

Jingcao Hu; Radu Marculescu

2004-01-01

295

Radiative strength functions in {sup 163,164}Dy  

SciTech Connect

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.

Nyhus, H. T.; Siem, S.; Guttormsen, M.; Larsen, A. C.; Buerger, A.; Syed, N. U. H.; Tveten, G. M. [Department of Physics, University of Oslo, N-0316 Oslo (Norway); Voinov, A. [Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701 (United States)

2010-02-15

296

Ag and Dy doped zeolite as a broadband phosphor  

NASA Astrophysics Data System (ADS)

Photoluminescence (PL) properties of silver (Ag) and dysprosium (Dy) codoped zeolites were investigated. It was found that PL from the 4F9/2-6H13/2 transition of Dy3+ ions at 575 nm is more than 50 times enhanced by the presence of Ag+ ions under ultraviolet excitation. The excitation wavelength dependence of the PL intensity coincided well with the absorption spectra of Ag+ ions, indicating that Dy3+ ions are excited by the energy transfer from Ag+ ions. In addition, by carefully optimizing annealing condition and Dy and Ag concentration, white light was realized due to the combination of blue emission of Ag+ ions, yellow emission of Dy3+ ions and red emission of Ag clusters.

Rong gui, Sa chu; Imakita, Kenji; Lin, Hui; Fujii, Minoru

2014-12-01

297

Defective muscle basement membrane and lack of M-laminin in the dystrophic dy/dy mouse.  

PubMed Central

M-laminin is a major member of the laminin family of basement membrane proteins. It is prominently expressed in striated muscle and peripheral nerve. M-laminin is deficient in patients with the autosomal recessive Fukuyama congenital muscular dystrophy but is normal in patients with the sex-linked Duchenne and Becker muscular dystrophies. We have examined M-laminin expression in mice with autosomal recessive muscular dystrophy caused by the mutation dy. The heavy chain of M-laminin was undetectable in skeletal muscle, heart muscle, and peripheral nerve by immunofluorescence and immunoblotting in homozygous dystrophic dy/dy mice but was normal in heterozygous and wild-type nondystrophic mice. Immunofluorescence confirmed the presence of other major basement membrane proteins in the dystrophic mice. Very low levels of M-laminin heavy chain mRNA were detected by Northern blotting of muscle and heart tissue from dy/dy mice, suggesting that M-laminin heavy-chain mRNA may be produced at very low levels or is unstable. Information about the chromosomal localization of the M heavy-chain in human and mouse suggests that a mutation in the M-chain gene causes the muscular dystrophy in dy/dy mice. The dy mouse may provide a model for autosomal muscular dystrophies in humans and facilitate studies of functions of M-laminin. Images PMID:8202529

Xu, H; Christmas, P; Wu, X R; Wewer, U M; Engvall, E

1994-01-01

298

The TB epidemic from 1992 to 2002.  

PubMed

In 1992, less than 20 countries were implementing a sound TB control strategy. At the same time, TB was being resurrected as a major public health problem world-wide after two decades of neglect. Awareness of upward trends in the industrialized countries and MDR-TB outbreaks in large cities were driving forces behind the re-emergence of TB in the international health agenda. New evidence, and consequent estimates, suggested that the situation in developing countries, especially in sub-Saharan Africa, was deteriorating rapidly. Similarly, major increases were observed in the former USSR. It was estimated that some 7-8 million new cases and 2-3 million deaths were occurring annually in the world. The global targets of reaching 85% cure rates and 70% case detection among infectious cases were established by the World Health Assembly in 1991. Both the WHO declaration of TB as a global emergency in 1993 and the launch of the five-element DOTS strategy in 1994-1995 resulted in countries adopting DOTS in encouraging numbers. In fact, in 2000, 148 countries including all 22 highest burden countries (HBC) responsible for 80% of cases world-wide, had adopted the new DOTS strategy. Nevertheless, progress in case detection remained slow due to incomplete geographical coverage or need to widen detection and notification capacity with innovative schemes. The major constraints to TB control became increasingly clear, and a global Stop TB Partnership was eventually established to address such constraints. A Global DOTS Expansion Plan revealed the needs and the gaps to achieve the global targets in 2005. Today, in 2002, the top priority remains that of expanding DOTS, as rapidly as possible, using a number of new approaches to increase case detection and notification while maintaining high cure rates. These must involve collaboration with the private sector and communities, as well as strengthening of primary care services. Similarly, crucial is the rapid identification of solutions to TB/HIV and MDR-TB. PMID:12758183

Raviglione, Mario C

2003-01-01

299

Valence photoelectron spectroscopy of Gd silicides  

SciTech Connect

Gd{sub 3}Si{sub 5}, GdSi, and Gd{sub 5}Si{sub 3} were investigated with photoemission spectroscopy in the photon-energy range 40.8--149 eV by exploiting the energy dependence of the photoemission cross sections and the valence resonance at the crossing of the Gd 4{ital d}-4{ital f} threshold. The modification of the spectra versus photon energy, along with their stoichiometry dependence, show the relevance of covalent mixed Gd 5{ital d}--Si 3{ital sp} states in the formation of the chemical bond. In the region close to the Fermi level an increase of the {ital d} contribution is observed. These points are discussed in connection with the existing models of the silicide bond.

Braicovich, L. (Istituto di Fisica, Politecnico di Milano, P.za Leonardo da Vinci 32, 20133 Milano, Italy (IT)); Puppin, E.; Lindau, I. (Stanford Electronics Laboratories, Stanford University, Stanford, California 94305 (USA)); Iandelli, A.; Olcese, G.L.; Palenzona, A. (Istituto di Chimica Fisica, Universita di Genova, Corso Europa, Palazzo delle Scienze, 16132 Genova, (Italy))

1990-02-15

300

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

301

Photophysical properties of a new DyLight 594 dye.  

PubMed

We describe spectral properties of novel fluorescence probe DyLight 594. Absorption and fluorescence spectra of this dye are in the region of Alexa 594 fluor spectra. The quantum yield of DyLight 594 in conjugated form to IgG is higher than corresponding quantum yield of Alexa 594 by about 50%. The new DyLight dye also shows slightly longer lifetime and photostability. These favorable properties and high anisotropy value, as well as a high cross-section for two-photon excitation, make this fluorophore attractive as a fluorescence probe in biochemical/biological studies involving fluorescence methods. PMID:19948414

Sarkar, Pabak; Sridharan, Savitha; Luchowski, Rafal; Desai, Surbhi; Dworecki, Boguslawa; Nlend, Marie; Gryczynski, Zygmunt; Gryczynski, Ignacy

2010-01-21

302

TAIMA (Stop) TB: The Impact of a Multifaceted TB Awareness and Door-to-Door Campaign in Residential Areas of High Risk for TB in Iqaluit, Nunavut  

PubMed Central

Background The incidence rate of active tuberculosis (TB) disease in the Canadian Territory of Nunavut has shown a rising trend over the past 10 years. In 2010 it was 60 times greater than the national incidence rate. The objective of the Taima (translates to stop in Inuktitut) TB study was to implement and evaluate a public health campaign to enhance existing TB prevention efforts in Nunavut. Methods A TB awareness campaign followed by a door-to-door screening campaign was carried out in Iqaluit, Nunavut. The aim of the campaign was to raise awareness about TB, and to provide in-home screening and treatment for people living in residential areas at high risk for TB. Screening was based on geographic location rather than on individual risk factors. Results During the general awareness campaign an increase in the number of people who requested TB testing at the local public health clinic was observed. However, this increase was not sustained following cessation of the awareness campaign. Targeted TB screening in high risk residential areas in Iqaluit resulted in 224 individuals having TSTs read, and detection of 42 previously unidentified cases of latent TB, (overall yield of 18.8% or number needed to screen?=?5.3). These cases of latent TB infection (LTBI) were extra cases that had not been picked up by traditional screening practices (34% relative increase within the community). This resulted in a 33% relative increase in the completion of LTBI treatment within the community. The program directly and indirectly identified 5/17 new cases of active TB disease in Iqaluit during the study period (29.5% of all incident cases). Conclusions While contact tracing investigations remain a cornerstone of TB prevention, additional awareness, screening, and treatment programs like Taima TB may contribute to the successful control of TB in Aboriginal communities. PMID:25033320

Alvarez, Gonzalo G.; VanDyk, Deborah D.; Aaron, Shawn D.; Cameron, D. William; Davies, Naomi; Stephen, Natasha; Mallick, Ranjeeta; Momoli, Franco; Moreau, Katherine; Obed, Natan; Baikie, Maureen; Osborne, Geraldine

2014-01-01

303

[166Dy]dysprosium/[166Ho]holmium in vivo generator.  

PubMed

A novel approach for the delivery of 166Ho (t1/2 = 26.6 h) to tissue is via the in vivo decay of its 81.5 h parent, 166Dy-an in vivo generator system. A critical question for the in vivo 166Dy/166Ho generator system is whether translocation of the daughter nucleus occurs. The in vitro and in vivo integrity of the [166Dy]Dy/166Ho-DTPA complex was investigated and results indicated that no translocation of the daughter nucleus occurs subsequent to beta- decay of 166Dy. Biodistribution studies of [166Dy]Dy-DTPA showed that the ratio of 166Dy/166Ho in bone remains constant (+/- 7%) over a 20 h period, indicating no significant in vivo loss of 166Ho from the complex. Increasing the in vivo residence time of [166Dy]Dy-DTPA complex attached to HSA gave similar results. PMID:7633391

Smith, S V; Di Bartolo, N; Mirzadeh, S; Lambrecht, R M; Knapp, F F; Hetherington, E L

1995-08-01

304

HIV-1 and the immune response to TB  

PubMed Central

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

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

2013-01-01

305

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

SciTech Connect

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 TbSn{sub 1.12}Ge{sub 0.88} (a) is sine-modulated described by the propagation vector k=(0.426, 0, 0.588). The magnetic structures of RSn{sub 1+x}Ge{sub 1-x} where R are Dy (b), Ho (b) and Er (c) at temperatures close to 1.5 K are described by the propagation vector k=(1/2, 1/2, 0) with the sequence (++-+) of magnetic moments in the crystal unit cell. For Ho- and Dy-compound this ordering is stable up to T{sub N} while for Er-compound at T{sub t}=3.5 K it tunes into a modulated structure (d). Highlights: > We determine crystal and magnetic structures of RSn{sub 1+x}Ge{sub 1-x} (R=Tb, Dy, Ho, Er, x{approx}0.1) compounds. > We compare the results with those for RT{sub x}X{sub 2} (X=Ge, Sn) compounds. > We examine the influence of other components (T, Sn, Ge) on magnetic ordering in R-sublattices. > Magnetic ordering in RSn{sub 1+x}Ge{sub 1-x} compounds is similar to those observed in RT{sub x}X{sub 2} compounds. > Other elements (T, Sn, Ge) have not got significant influence on stability of magnetic ordering.

Gil, A., E-mail: a.gil@ajd.czest.pl [Department of Mathematics and Natural Sciences, J. Dlugosz University Czestochowa, Armii Krajowej 13/15, PL 42-200 Czestochowa (Poland); Penc, B.; Baran, S. [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, PL 30-059 Krakow (Poland); Hoser, A. [BENSC, Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, D 14109 Berlin (Germany); Szytula, A. [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, PL 30-059 Krakow (Poland)

2011-07-15

306

Phosphor thermometry in turbulent hot gas flows applying Dy:YAG and Dy:Er:YAG particles  

NASA Astrophysics Data System (ADS)

In order to improve the phosphorescence emission behavior of phosphor powders for temperature measurements in a gas flow, the activator concentration in Dy:YAG was varied and the phosphor was co-doped with the sensitizer erbium (Er). Phosphorescence spectra, overall phosphorescence signal intensities and the phosphorescence lifetime were characterized in a furnace up to 1400?K. Planar thermometry was conducted in hot gas flows, whereby an improved average temperature uncertainty of about 3% was obtained using Dy:YAG and of 1.8% for Dy:Er:YAG for temperatures of 450?K.

Jovicic, Gordana; Zigan, Lars; Will, Stefan; Leipertz, Alfred

2015-01-01

307

KCl:Dy phosphor for thermoluminescence dosimetry of ionizing radiation.  

PubMed

The thermoluminescence (TL) characterizations of ?-irradiated KCl:Dy phosphor for radiation dosimetry are reported. All phosphors were synthesized via a wet chemical route. Minimum fading of TL intensity is recorded in the prepared material. TL in samples containing different concentrations of Dy impurity was studied at different ?-irradiation doses. Peak TL intensities varied sublinearly with ?-ray dose in all samples, but were linear between 0.08 to 0.75 kGy for the KCl:Dy (0.1 mol%) sample. This material may be useful for dosimetry within this range of ?-ray dose. TL peak height was found to be dependant on the concentration (0.05-0.5 mol%) of added Dy in the host. PMID:23255424

Bhujbal, P M; Dhoble, S J

2013-01-01

308

Spin-echo NMR of 159Tb in a single crystal of TbNi5  

Microsoft Academic Search

The field dependence of the hyperfine splittings of 159Tb in a single crystal of TbNi5 has been studied at liquid helium temperature by spin-echo NMR. The field, up to 8 tesla, was applied along the direction of easy magnetization of the crystal. Our measurements are in almost perfect agreement with computation based on the mean values of the crystal field

C. Carboni; D. Gignoux; A. Tari

1995-01-01

309

Air stability and magnetic properties of GdN, TiN, and (Gd,Ti)N nanoparticles  

Microsoft Academic Search

GdN, TiN, and (Gd,Ti)N nanoparticles were prepared by arc evaporating Gd, Ti, and Gd-Ti alloys in N2, respectively. Most of these nanoparticles show narrow size distribution with average diameter of 20nm. Shell\\/core structure\\u000a was observed in the (Gd,Ti)N nanoparticles, in which the shell was formed by surface reaction with air. (Gd,Ti)N nanoparticles\\u000a are more stable than GdN nanoparticles in air

Ping-Zhan Si; C. J. Choi; O. Tegus; E. Brck; D. Y. Geng; Z. D. Zhang

2008-01-01

310

Comparison of the Sequence-Dependent Fluorescence of the Cyanine Dyes Cy3, Cy5, DyLight DY547 and DyLight DY647 on Single-Stranded DNA  

PubMed Central

Cyanine dyes are commonly used for fluorescent labeling of DNA and RNA oligonucleotides in applications including qPCR, sequencing, fluorescence in situ hybridization, Frster resonance energy transfer, and labeling for microarray hybridization. Previous research has shown that the fluorescence efficiency of Cy3 and Cy5, covalently attached to the 5? end of single-stranded DNA, is strongly sequence dependent. Here, we show that DY547 and DY647, two alternative cyanine dyes that are becoming widely used for nucleic acid labeling, have a similar pattern of sequence-dependence, with adjacent purines resulting in higher intensity and adjacent cytosines resulting in lower intensity. Investigated over the range of all 1024 possible DNA 5mers, the intensities of Cy3 and Cy5 drop by ?50% and ?65% with respect to their maxima, respectively, whereas the intensities of DY547 and DY647 fall by ?45% and ?40%, respectively. The reduced magnitude of change of the fluorescence intensity of the DyLight dyes, particularly of DY647 in comparison with Cy5, suggests that these dyes are less likely to introduce sequence-dependent bias into experiments based on fluorescent labeling of nucleic acids. PMID:24454899

Kretschy, Nicole; Somoza, Mark M.

2014-01-01

311

Universality of Anharmonic Motion of Heavy Rare-Earth Atoms in Hexaborides  

NASA Astrophysics Data System (ADS)

Phonons of TbB6 are studied by inelastic X-ray scattering and compared with those of GdB6 and DyB6. Measured low-lying phonon modes located near 6 meV soften distinctly with decreasing temperature, particularly the longitudinal phonon that is dominated by the motion of Tb ions at boldsymbol{{q}}1 = (1/2,0,0). The magnitude and temperature dependence of phonon energy are between those of GdB6 and DyB6. We derive a Landau-type free-energy expansion with respect to the atomic displacement in TbB6, and discuss a general feature among these three compounds. The systematic variation in the phonon characteristics of these hexaborides and the first-order-like instability indicate the universality of the anharmonic motion of heavy rare-earth atoms in RB6 (R = Gd, Tb, and Dy).

Iwasa, Kazuaki; Iga, Fumitoshi; Yonemoto, Ari; Otomo, Yuka; Tsutsui, Satoshi; Baron, Alfred Q. R.

2014-09-01

312

High pressure effect on structural, elastic and thermal properties of DyP and DyAs  

NASA Astrophysics Data System (ADS)

We have performed an inter-ionic potential theory with modified ionic charge to investigate the structural, elastic and thermal properties of DyP and DyAs theoretically, at high pressure. We found a structural phase transition from NaCl (B1) - to CsCl (B2)-type structure at 57 GPa for DyP and 51 GPa for DyAs and other properties, such as lattice constant, bulk modulus, cohesive energy and second-order elastic constants were also calculated and compared with the available theoretical data. In order to gain further information, we have also predicted the Young's modulus (E), Poisson's ratio (v), anisotropy factor (A) and Debye temperature (?D). Our results are in good agreement with theoretical data where available and provide predictions where they are not.

Bhajanker, Sanjay; Srivastava, Vipul; Sanyal, S. P.

2012-07-01

313

Tailoring the magnetism of Tb5Si2Ge2 compounds by La substitution  

SciTech Connect

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.

Belo, Joao [University of Porto, Portugal; Pereira, Andre [University of Porto, Portugal; Araujo, Joao Pedro [University of Porto, Portugal; Dela Cruz, Clarina R [ORNL; Moreira Dos Santos, Antonio F [ORNL; Goncalves, Joao Nuno [University of Porto, Portugal; Amaral, Vitor [University of Aveiro, Portugal; Morellon, Luis [University of Zaragoza, Spain; Ibarra, M. Ricardo [University of Zaragoza, Spain; Algarabel, Pedro A. [University of Zaragoza, Spain; Magen, C [Instituto de Ciencia de Materiales de Aragn, Universidad de Zaragoza-CSIC, Zaragoza, 50009 Spain

2012-01-01

314

Gaps in the GD-1 Star Stream  

NASA Astrophysics Data System (ADS)

GD-1 is a long, thin, Milky Way star stream that has readily visible density variations along its length. We quantify the locations, sizes, and statistical significance of the density structure, i.e., gaps, using a set of scaled filters. The shapes of the filters are based on the gaps that develop in simulations of dark matter sub-halos crossing a star stream. The high Galactic latitude 8.4 kpc long segment of GD-1 that we examine has 8 3 gaps of 99% significance or greater, with the error estimated on the basis of tests of the gap-filtering technique. The cumulative distribution of gaps more than three times the width of the stream is in good agreement with predictions for dark matter sub-halo encounters with cold star streams. The number of gaps narrower than three times the width of the GD-1 stream falls well below the cold stream prediction which is taken into account for the gap creation rate integrated over all sizes. Simple warm stream simulations scaled to GD-1 show that the falloff in gaps is expected for sub-halos below a mass of 106 M ?. The GD-1 gaps requires 100 sub-halos >106 M ? within 30 kpc, the apocenter of GD-1 orbit. These results are consistent with LCDM sub-halo predictions but further improvements in stream signal-to-noise and gap modeling will be welcome.

Carlberg, R. G.; Grillmair, C. J.

2013-05-01

315

pH-induced Dy? and Dy?? cluster-based 1D chains with different magnetic relaxation features.  

PubMed

Two novel tetra- and deca-nuclear dysprosium compounds, namely, [Dy4(?3-OH)2(L)10(bipy)2(H2O)2]n (1) and {[Dy10(?3-OH)8(L)22(bipy)2(H2O)2]5H2O}n (2) (L = 3-fluoro-4-(trifluoromethyl)benzoic acid; bipy = 2,2'-bipyridine), have been successfully obtained by hydrothermal reaction at different pH values. The solid state structures of 1 and 2 were established by the single crystal X-ray diffraction technique, and both of them exhibit complicated 1D chains with [Dy4] (1) and [Dy10] (2) cluster units, respectively. Adjacent [Dy4] in 1 and [Dy10] in 2 are connected by two bridging carboxylate groups in the ?(1):?(1):?2 mode. Magnetic studies reveal that they exhibit different magnetic relaxation behaviors with the energy barrier of 23.6 K for 1 and 3.2 K for 2. Interestingly, the large divergence in both the structures and magnetic properties for 1 and 2 only originated from the different pH values in preparing them. PMID:25293936

Wu, Zhi-Lei; Dong, Jie; Ni, Wei-Yan; Zhang, Bo-Wen; Cui, Jian-Zhong; Zhao, Bin

2014-11-28

316

Reinvestigation of the CdGd phase diagram  

PubMed Central

The complete CdGd 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 465C. 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 22.6at.%, 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 700C. PMID:25544803

Reichmann, Thomas L.; Ipser, Herbert

2014-01-01

317

Gyromagnetic ratios of 4 + and 6 + states in 156 Gd and 158 Gd  

Microsoft Academic Search

The followingg-factors have been derived from time integral measurements of ?-? angular correlations in the static magnetic hyperfine field of magnetized gadolinium metal probes:156Gd:g(41+)=+0.310(19)g(61+)=+0.25(21)g(43+, 1511 keV)=+0.809(27)158Gd:g(41+)=+0.409(15).

A. Alzner; E. Bodenstedt; B. Gemnden; J. van den Hoff; S. Fiel; R. Sajok; H. Koch; Th. Schfer; R. Vianden

1988-01-01

318

Cytotoxic and genotoxic effect of the [166Dy]Dy/166Ho-EDTMP in vivo generator system in mice.  

PubMed

Multiple myeloma and other hematological malignancies have been treated by myeloablative radiotherapy/chemotherapy and subsequent stem cell transplantation. [(166)Dy]Dy/(166)Ho-ethylenediaminetetramethylene phosphonate (EDTMP) forms a stable in vivo generator system with selective skeletal uptake in mice; therefore, it could work as a potential and improved agent for marrow ablation. Induced bone marrow cytotoxicity and genotoxicity are determined by the reduction of reticulocytes (RET) and elevation of micronucleated reticulocyte (MN-RET) in peripheral blood and ablation by bone marrow histological studies. The aim of this study was to determine the bone marrow cytotoxic and genotoxic effect of the [(166)Dy]Dy/(166)Ho-EDTMP in vivo generator system in mice and to evaluate by histopathology its myeloablative potential. Enriched (166)Dy(2)O(3) was irradiated and [(166)Dy]DyCl(3) was added to EDTMP in phosphate buffer (pH 8.0) in a molar ratio of 1:1.75. QC was determined by TLC. Dy-EDTMP complex was prepared the same way with nonirradiated dysprosium oxide. A group of BALB/c mice were intraperitoneally injected with the radiopharmaceutical and two groups of control animals were injected with the cold complex and with 0.9% sodium chloride, respectively. A blood sample was taken at the beginning of the experiments and every 48 h for 12 days postinjection. The animals were sacrificed, organs of interest taken out and the radioactivity determined. The femur was used for histological studies. Flow cytometry analysis was used to quantify the frequency of RET and MN-RET in the blood samples. The MCNP4B Monte Carlo computer code was used for dosimetry calculations. Radiochemical purity was 99% and the mean specific activity was 1.3 MBq/mg. The RET and MN-RET frequency were statistically different in the treatment at the end of the 12-day period demonstrating cytotoxicity and genotoxicity induced by the in vivo generator system. The histology studies show that there was complete, or almost complete, acellularity, which means significant suppression of the bone marrow activity. Bone marrow absorbed dose was 18-23 Gy. [(166)Dy]Dy/(166)Ho-EDTMP induces cytotoxicity, genotoxicity and severe myelosuppression in mice. Potentially, it is a good agent for use in humans. PMID:15607490

Pedraza-Lpez, Martha; Ferro-Flores, Guillermina; Arteaga de Murphy, Consuelo; Morales-Ramrez, Pedro; Piedras-Ross, Josefa; Murphy-Stack, Eduardo; Hernndez-Oviedo, Omar

2004-11-01

319

Antiferromagnetic behaviour of Tb2Al alloy  

Microsoft Academic Search

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

D. P. Rojas; G. Andr; J. Rodrguez Fernndez; J. Snchez Marcos; L. Fernndez Barqun; C. Echevarria

2011-01-01

320

New TB treatments hiding in plain sight  

PubMed Central

As tuberculosis (TB) toll is revised upward according to the WHO's last estimates, the lack of vaccine strategy and the lengthy antibiotic treatments that unfortunately promote the emergence of drug resistance are a major set back in the fight against this pathogen. In this issue of EMBO Molecular Medicine, Schiebler etal (Mtb) propose a novel and compelling new approach to target Mycobacterium tuberculosis (Mtb) by pharmacologically stimulating intracellular mycobacteria clearance through autophagy. PMID:25535253

Olive, Andrew J; Sassetti, Christopher M

2015-01-01

321

Deterministic Compartmental Models for HIV and TB  

Microsoft Academic Search

Abstract This research provides a detailed review of a deterministic compartmental,model,for Human Immunodeficiency Virus (HIV) and tuberculosis (TB) to understand better the dynamics,of the twin epidemics in a South African township. This model is built on SIR and population models. The HIV epidemic in Southern Africa constitutes the most serious health problem in the region. What makes,the study and control

Eric Okyere; John Hargrove

2007-01-01

322

Magnetism in Gd-W filmsa)  

NASA Astrophysics Data System (ADS)

Vapor condensation techniques are useful to prepare magnetic alloys whose components have low or even negligible equilibrium mutual solubility. In this work, one of these techniquessputteringwas used to obtain GdxW1-x alloys whose magnetic properties were investigated as a function of the Gd atomic concentration x. Gadolinium and various Gd-based alloys are promising materials for magnetic refrigeration and this was one of the motivations for this study. The Gdx-W1-x films were sputter deposited from Gd and W targets with x ranging from 0 to 1 as determined by x-ray energy-dispersive spectroscopic analyses. X-ray diffraction patterns indicate that crystalline structures were formed at low and high Gd concentrations, while at intermediate concentrations, the films were amorphous. Magnetization measurements, performed as a function of temperature and with static and alternating applied fields, reveal a spin glasslike behavior in all the W-containing samples for temperatures below the freezing temperature Tf. For low and intermediate Gd concentrations, and for T >Tf, the films were paramagnetic, while a ferromagnetic phase was observed in the Gd-W alloy of the highest Gd content. The magnetocaloric effect was investigated from the magnetization isotherms M versus H, from which the isothermal magnetic entropy variation ?SM as a function of T, for the removal of an applied field of 50kOe, was determined. It was observed that the maximum value of ?SM for each ?SM versus T curve and the temperature at which these maxima occur, are strongly dependent on x.

Gadioli, Giovana Z.; Rouxinol, Francisco P.; Gelamo, Rogrio V.; dos Santos, Adenilson O.; Cardoso, Lisandro P.; Bica de Moraes, Mrio A.

2008-05-01

323

A Toolbox for Tuberculosis (TB) Diagnosis: An Indian Multicentric Study (20062008). Evaluation of QuantiFERON-TB Gold in Tube for TB Diagnosis  

PubMed Central

Background The aim of this multicentric prospective study in India was to assess the performance of the QuantiFERON TB-Gold in tube (QFT-GIT), Tuberculin Skin Test (TST) and microbiological results as additional tools for diagnosing active tuberculosis (TB) and latent infection (LTBI) according to Human Immunodeficiency Virus (HIV) status. Methods Individuals with and without active TB and HIV infection were enrolled between 20062008. QFT-GIT and TST results were analyzed per se and in combination with microbiological data. Results Among the 276 individuals (96 active pulmonary TB and 180 no active TB) tested by QFT-GIT, 18 indeterminate results (6.5%) were found, more significantly numerous in the HIV-infected (15/92; 16.3%) than the HIV-uninfected (3/184; 1.6%)(p<0.0001). QFT-GIT sensitivity for active TB was 82.3% and 92.9% respectively after including or excluding indeterminate results. Clinical sensitivity was significantly lower in the HIV-infected (68.4%) than the HIV-uninfected (91.4%) patients (p?=?0.0059). LTBI was detected in 49.3% of subjects without active TB but varied according to TB exposure. When the TST and QFT-GIT were concomitantly performed, the respective sensitivity for active TB diagnosis was 95.0% and 85.0% in the HIV-uninfected (p?=?0.60), and 66.7% and 51.5% in the HIV-infected patients (p?=?0.32). QFT-GIT and TST respective specificity for active TB in the HIV-uninfected was 25.0% and 57.1% (p?=?0.028), and 64.8% and 83.3% in the HIV-infected (p?=?0.047). In those with active TB, QFT-GIT results were not associated with microbiological parameters (smear grade, liquid culture status, time-to-positivity of culture) or clinical suspicion of active TB score (provided by the clinicians at enrollment). Combining microbiological tests with both immunological tests significantly increased sensitivity for active TB diagnosis (p?=?0.0002), especially in the HIV-infected individuals (p?=?0.0016). Conclusion QFT-GIT and TST have similar diagnostic value for active TB diagnosis. In HIV-infected patients, combining microbiological tests with both immunological tests significantly increases the sensitivity for active TB diagnosis. PMID:24039990

Lagrange, Philippe H.; Thangaraj, Satheesh K.; Dayal, Rajeshwar; Deshpande, Alaka; Ganguly, Nirmal K.; Girardi, Enrico; Joshi, Beenu; Katoch, Kiran; Katoch, Vishwa M.; Kumar, Manoj; Lakshmi, Vemu; Leportier, Marc; Longuet, Christophe; Malladi, Subbalaxmi V. S.; Mukerjee, Deepali; Nair, Deepthi; Raja, Alamelu; Raman, Balambal; Rodrigues, Camilla; Sharma, Pratibha; Singh, Amit; Singh, Sarman; Sodha, Archana; Kabeer, Basirudeen Syed Ahamed; Vernet, Guy; Goletti, Delia

2013-01-01

324

Decay properties of long-lived isomers in the odd-odd N=81 nucleus {sup 146}Tb compared to the {sup 148}Ho and {sup 150}Tm nuclei  

SciTech Connect

Excited states of the {sup 146}Tb nucleus have been studied using {gamma}-ray and electron spectroscopy in off-beam and in-beam modes following {sup 112}Sn({sup 40}Ar,3n3p) reaction with the use of the OSIRIS-II, HPGe detector array and the conversion electron spectrometer. The multipolarity of the 343 keV transition deexciting the (7{sup -}) level in {sup 146}Tb shows mainly an E2 nature and the first excited state above the 23 s isomer is assigned as a (5{sup -},6{sup -}) state. The log ft values have been deduced for 11 {beta}{sup +}/EC transitions populating excited states in {sup 146}Gd. The systematic behavior of spins and parities of the long-lived levels at 0+x keV and the first excited states above them in the N=81 isotones {sup 146}Tb, {sup 148}Ho, and {sup 150}Tm is discussed.

Kownacki, J.; Kisielinski, M. [Heavy Ion Laboratory, University of Warsaw, Warsaw (Poland); Andrzej Soltan Institute for Nuclear Studies, Swierk (Poland); Droste, Ch.; Morek, T.; Ruchowska, E.; Grodner, E. [Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw (Poland); Lieder, R. M. [Institut fuer Kernphysik Forschungszentrum Juelich, Juelich (Germany); Kowalczyk, M.; Wrzosek-Lipska, K.; Hadynska-KlePk, K.; Mierzejewski, J. [Heavy Ion Laboratory, University of Warsaw, Warsaw (Poland); Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw (Poland); Andrzejewski, J.; Perkowski, J. [Faculty of Physics, University of Lodz, Lodz Poland (Poland); Napiorkowski, P. J.; Zielinska, M.; Kordyasz, A.; Srebrny, J. [Heavy Ion Laboratory, University of Warsaw, Warsaw (Poland); Korman, A. [The Andrzej Soltan Institute for Nuclear Studies, Swierk (Poland)

2011-02-15

325

Incidence of TB and HIV in Prospectively Followed Household Contacts of TB Index Patients in South Africa  

PubMed Central

Objective To report the incidence rates of TB and HIV in household contacts of index patients diagnosed with TB. Design A prospective cohort study in the Matlosana sub-district of North West Province, South Africa. Methods Contacts of index TB patients received TB and HIV testing after counseling at their first household visit and were then followed up a year later, in 2010. TB or HIV diagnoses that occurred during the period were determined. Results For 2,377 household contacts, the overall observed TB incidence rate was 1.3 per 100 person years (95% CI 0.91.9/100py) and TB incidence for individuals who were HIV-infected and HIV seronegative at baseline was 5.4/100py (95% CI 2.99.0/100py) and 0.7/100py (95% CI 0.31.4/100py), respectively. The overall HIV incidence rate was 2.2/100py (95% CI 1.38.4/100py). Conclusions In the year following a household case finding visit when household contacts were tested for TB and HIV, the incidence rate of both active TB and HIV infection was found to be extremely high. Clearly, implementing proven strategies to prevent HIV acquisition and preventing TB transmission and progression to disease remains a priority in settings such as South Africa. PMID:24759741

van Schalkwyk, Cari; Variava, Ebrahim; Shapiro, Adrienne E.; Rakgokong, Modiehi; Masonoke, Katlego; Lebina, Limakatso; Welte, Alex; Martinson, Neil

2014-01-01

326

Synthesis, crystalline structure and photoluminescence investigations of the new trivalent rare earth complexes (Sm 3+, Eu 3+ and Tb 3+) containing 2-thiophenecarboxylate as sensitizer  

Microsoft Academic Search

New complexes with the general formula [RE(TPC)3(H2O)2], where RE=Eu3+, Sm3+, Gd3+, Tb3+ and TPC=2-thiophenecarboxylate, have been prepared and investigated by photoluminescence spectroscopy. These compounds were characterized by complexometric titration, elemental analyses and infrared spectroscopy. The X-ray crystal structure has been determined for the [Eu(TPC)3(H2O)2] compound, indicating that this complex is in dimeric form bridged by two carboxylate ions with monoclinic

Ercules E. S Teotonio; Maria Cludia F. C Felinto; Hermi F Brito; Oscar L Malta; Antnio C Trindade; Renato Najjar; Wieslaw Strek

2004-01-01

327

Effect of Dy additions on microstructure and magnetic properties of Fe-Nd-B magnets  

Microsoft Academic Search

It is shown that increasing additions of Dy causes the remanence B\\/sub r\\/ to decrease linearly. The intrinsic coercivity, iHc, increases sharply for small additions of Dy, but the increase is not proportional for higher Dy contents. The iHc increases almost linearly with the effective anisotropy field of the REFeB phase until the Dy content is about 10% of the

R. Ramesh; G. Thomas; B. M. Ma

1987-01-01

328

High resolution magnetic resonance imaging of the brain in the dy/dy mouse with merosin-deficient congenital muscular dystrophy.  

PubMed

Magnetic resonance imaging (MRI) abnormalities in the cerebral white matter are a consistent feature of merosin-deficient human congenital muscular dystrophy, a disease caused by a primary defect in the expression of the laminin alpha2 chain of merosin. To investigate the relationship between imaging changes and merosin deficiency we undertook a MRI study in the dy/dy mouse, an animal model for this form of human congenital muscular dystrophy. High resolution in vivo imaging was performed on anaesthetized animals (two homozygous dy/dy mutants and two heterozygous dy/DY controls, aged 2.5 months) in a dedicated 11.7T magnetic resonance imaging scanner. T(1) and T(2) weighted images were normal in all mice and white matter changes were not seen at a stage of maturity when MRI changes are already very striking in human patients. Cerebral MRI abnormalities do not appear to be a feature of dy/dy mice, despite the virtual absence of merosin expression in the dy/dy mouse brain. Possible causes for this absence of MRI changes, and implications for the pathogenesis of the MRI changes in humans are reviewed. PMID:10838257

Dubowitz, D J; Tyszka, J M; Sewry, C A; Moats, R A; Scadeng, M; Dubowitz, V

2000-06-01

329

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

E-print Network

, Ho a ferrimagnetic coupling is observed in the Fe substi- tuted compounds. The Curie temperatures can be analyzed for constant x using a de Gennes function. The con- centration dependence of Tc might be explained be detected at 4 K from bulk magnetic measurements and also from Moss- bauer investigations only quadrupole

Boyer, Edmond

330

Extensively drug resistance (XDR) tb is not always fatal.  

PubMed

The chance of incidence of XDR TB is on the rise due to improper use of second line anti-tubercular drugs. XDR-TB is very difficult to treat successfully and is often referred to as "virtually untreatable form of TB". We herein report a case of XDR TB confirmed by bacteriological examination in a WHO recognised laboratory who after 12 months of regular treatment improved both clinically and radiologically with sputum smear conversion. To the best of our knowledge, there has been no previous report of any similar case in literature. PMID:19402272

Jain, N K; Agnihotri, S P; Sharma, Krishan K; Gupta, Shikha; Gupta, Pawan

2009-01-01

331

Choroidal tuberculoma showing paradoxical worsening in a patient with miliary TB.  

PubMed

Abstract Tuberculosis (TB) remains an important public health problem worldwide. Ocular involvement in patients with systemic TB has traditionally been considered uncommon. Diagnosing ocular TB is challenging and often delayed, especially in the absence of pulmonary signs or symptoms typical of TB. Here we describe a case of paradoxical reaction after antituberculosis therapy in an immunocompetent patient with ocular TB. PMID:25140405

Yilmaz, Turgut; Selcuk, Engin; Polat, Nihat; Mutlu, Kayhan

2015-02-01

332

Magnetoelectric characteristics of Dy2.8Sr0.2Fe5O12 garnet (DySrIG)  

NASA Astrophysics Data System (ADS)

The effect of dc magnetic field on the capacitance, impedance and resistance of Dy2.8Sr0.2Fe5O12 (DySrIG) prepared using the citrate-nitrate auto-combustion method was studied at room temperature. The measurements were carried out in two ways; the first one in which the dc magnetic field and the ac electric field are parallel (//) to each other and the second one in which the magnetic field and ac electric fields are perpendicular (?) to each other. The magnetoimpedance of Dy2.8Sr0.2Fe5O12 increases by about 80% in the (?) case (at 1650 Oe and 450 kHz) with respect to its values at zero magnetic field. The results of the study encourage the use of this garnet nanomaterial in magnetic sensors, in new devices including tunable filter and spintronic applications.

Ahmed, M. A.; Bishay, S. T.; El-dek, S. I.

2012-08-01

333

LABORATORY EVALUATION OF A DYED FOOD MARKING TECHNIQUE FOR CULEX QUINQUEFASCIATUS (DIPTERA: CULICIDAE)  

Technology Transfer Automated Retrieval System (TEKTRAN)

A method of marking adult Cx. quinquefasciatus by feeding the larvae commercial hog chow dyed with methylene blue, Giemsa, and crystal violet was evaluated under laboratory conditions. Of 243 mosquitoes fed the dyed food, 230 had visible marks (94.6 %). The dyed food did increase the development tim...

334

White light emission and energy transfer in Dy3+/Eu3+ co-doped aluminoborate glass  

NASA Astrophysics Data System (ADS)

The Dy3+ single doped calcium aluminoborate glass (CaO-Al2O3-B2O3-Dy2O3) was synthesized by melt quenching method and the photoluminescence properties of Dy3+ were studied. Under UV-light excitation the CaO-Al2O3-B2O3-Dy2O3 glass shows a yellowish white light emission and the optimum content of Dy3+ in glass is found at 0.022 mol. For getting pure white light emission, the Dy3+/Eu3+ co-doped glasses with the compositions of Ca0.978-yAlB:Dy3+0.022, Euy3+ (y = 0-0.0938 mol) have been synthesized and the chromatic coordinates were calculated from their emission spectra. The results showed that the white light has been achieved by exciting Dy3+/Eu3+ co-doped glass with ultraviolet or blue light. The energy transfer phenomenon between Dy3+ and Eu3+ ions was validated in Dy3+/Eu3+ co-doped glasses and the decay rates for 4F9/2 level of Dy3+ ions have been measured. The energy transfer probabilities (Pda) are linear with acceptor (Eu3+) contents in the range of 0-0.0563 mol, confirming the fact that the dipole-dipole interaction is responsible for the energy transfer (ET) process of Dy3+ ? Eu3+.

Cai, Jia-li; Li, Ruo-ying; Zhao, Chong-jian; Tie, Shao-long; Wan, Xia; Shen, Jun-ying

2012-05-01

335

The analysis of thermoluminescent glow peaks of CaF : Dy (TLD-200) after -irradiation  

E-print Network

The analysis of thermoluminescent glow peaks of CaF 2 : Dy (TLD-200) after -irradiation of thermoluminescent glow peaks of CaF2 : Dy (TLD-200) after -irradiation A Necmeddin Yazici1,4 , Reuven Chen2 , Semra : Dy, LiF : Mg : Ti(TLD-100) and some other thermoluminescent materials, relatively little work has

Chen, Reuven

336

Isolated appendicular tuberculosis (TB) presented as peritonitis.  

PubMed

Tuberculosis is very common entity in both developing and under developed countries. Each year 3 million people worldwide died of the disease. Among extra pulmonary TB, alimentary system accounts for about 3.0% cases. The Commonest presentation of alimentary tuberculosis is Ileo-caecal disease, but isolated appendicular involvement is very rarely seen. Although some cases have been reported from our neighboring countries, there is still no such report from Bangladesh. We are here for the first time reporting a case of isolated appendicular tuberculosis which presented to us with peritonitis. PMID:20677612

Chowdhury, F R; Amin, M R; Khan, K H; Alam, M B; Ahasan, H A M N

2010-03-01

337

EPR Study of Gd3+-VM and Gd3+-Li+ Centres in Several Perovskite Fluorides  

NASA Astrophysics Data System (ADS)

EPR measurements on Gd3+ centres in KCdF3, RbCdF3, RbCaF3, CsCdF3 and CsCaF3 for crystals co-doped with Li+ ions have been made in the cubic phase of host crystals. In all the crystals spectra for Gd3+ centres associated with both cation vacancy (VM) and Li+ ion at the nearest divalent cation site have been observed. The observed parameters b20 and b44 in the spin Hamiltonian show various dependences on lattice constant in the series of fluorides with the same divalent (Cd2+ or Ca2+) or the same monovalent (Cs+ or Rb+) cation. The differences of the magnitude of b20 and b44 for Gd3+-Li+ centre from that for Gd3+-VM centre in the same host crystal are discussed.

Arakawa, Masanori; Ebisu, Hiroshi; Takeuchi, Hideo

1985-09-01

338

A neutron transmission study of environmental Gd  

E-print Network

A new method for the determination of environmental Gd by neutron transmission (NT) experiments is proposed. The NT method is based on the measurements of neutron spectra passing through a target. From the attenuation neutron spectra new data as concentration, width, resonance energies and cross section have been obtained.

Cristiana Oprea; Ioan Alexandru Oprea; Alexandru Mihul

2014-06-02

339

TheugsofWar TIM BON YH DY & NIGEL LENDON  

E-print Network

TheugsofWar TIM BON YH DY & NIGEL LENDON #12;The ugs of War #12;TThhee RRuuggss ooff WWaarr iiss of the Australian National University, Canberra ACT 0200. Copyright © 2003 by Tim Bonyhady, Nigel Lendon and Jasleen ­ Private collections ­ Australia. I. Bonyhady, Tim, 1957­ . II. Nigel Lendon, 1944­ . III. Australian

Botea, Adi

340

Structural and phase dependent thermo and photoluminescent properties of Dy(OH){sub 3} and Dy{sub 2}O{sub 3} nanorods  

SciTech Connect

Graphical abstract: Packing diagram of (a) hexagonal Dy(OH){sub 3} and (b) cubic Dy{sub 2}O{sub 3} nanorods. Highlights: ? Hexagonal Dy(OH){sub 3} and Dy{sub 2}O{sub 3} nanorods were prepared by hydrothermal route. ? Phase dependent PL and TL studies were carried out. ? The kinetic parameters such as activation energy (E), order of kinetics (b), and frequency factor (s) were estimated using peak shape method. ? Linear response of cubic Dy{sub 2}O{sub 3} phase is useful for its application in dosimetry. -- Abstract: Hexagonal Dy(OH){sub 3} and cubic Dy{sub 2}O{sub 3} nanorods were prepared by hydrothermal method. Dy(OH){sub 3} nanorods was directly obtained at 180 C for 20 h after hydrothermal treatment whereas subsequently heat treatment at 750 C for 2 h gives pure cubic Dy{sub 2}O{sub 3}. SEM micrographs reveal that needle shaped rods with different sizes were observed in both the phases. TEM results also confirm this. The TL response of hexagonal Dy(OH){sub 3} and cubic Dy{sub 2}O{sub 3} nanorods have been analyzed for ?-irradiation over a wide range of exposures (15 kGy). TL glow peak intensity increases with ? dose in both the phases. The activation energy (E), order of kinetics (b), and frequency factor (s) for both the phases have been determined using Chen's peak shape method. The simple glow curve shape, structure and linear response to ?-irradiation over a large span of exposures makes the cubic Dy{sub 2}O{sub 3} as a useful dosimetric material to estimate high exposures of ?-rays.

Chandrasekhar, M. [Prof. C.N.R. Rao centre for Nano Research (CNR), Tumkur University, Tumkur 572103 (India) [Prof. C.N.R. Rao centre for Nano Research (CNR), Tumkur University, Tumkur 572103 (India); Department of Physics, Acharya Institute of Technology, Bangalore 560090 (India); Sunitha, D.V. [Prof. C.N.R. Rao centre for Nano Research (CNR), Tumkur University, Tumkur 572103 (India)] [Prof. C.N.R. Rao centre for Nano Research (CNR), Tumkur University, Tumkur 572103 (India); Dhananjaya, N. [Department of Physics, B.M.S. Institute of Technology, Bangalore 560064 (India)] [Department of Physics, B.M.S. Institute of Technology, Bangalore 560064 (India); Nagabhushana, H., E-mail: bhushanvl@gmail.com [Prof. C.N.R. Rao centre for Nano Research (CNR), Tumkur University, Tumkur 572103 (India); Sharma, S.C. [Prof. C.N.R. Rao centre for Nano Research (CNR), Tumkur University, Tumkur 572103 (India)] [Prof. C.N.R. Rao centre for Nano Research (CNR), Tumkur University, Tumkur 572103 (India); Nagabhushana, B.M. [Department of Chemistry, M.S. Ramaiah Institute of Technology, Bangalore 560054 (India)] [Department of Chemistry, M.S. Ramaiah Institute of Technology, Bangalore 560054 (India); Shivakumara, C. [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012 (India)] [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012 (India); Chakradhar, R.P.S. [National Aerospace Laboratories (CSIR), Bangalore 560017 (India)] [National Aerospace Laboratories (CSIR), Bangalore 560017 (India)

2012-08-15

341

Structure and magnetic properties of bulk nanocrystalline Dy metal prepared by spark plasma sintering  

SciTech Connect

The structure and magnetic properties were studied for bulk nanocrystalline dysprosium (Dy) metal prepared by spark plasma sintering method. All the as-prepared samples have hexagonal close packed structure. A decrease in grain size results in remarkable changes in magnetic ordering temperature of the nanocrystalline Dy metal. At 5 K, the magnetization drops by 3.35%, and the coercive force increases by three times for nanocrystalline Dy compared to those of coarse-grained bulk Dy sample. These results indicate the remarkable influence of the nanostructure on the magnetism of Dy due to finite size effect.

Yue, M.; Wang, K. J.; Liu, W. Q.; Zhang, D. T.; Zhang, J. X. [The Key Laboratory of Advanced Functional Materials, Ministry of Education, and College of Materials Science and Engineering, Beijing University of Technology, Beijing 100022 (China)

2008-11-17

342

46 CFR 35.40-30 - Instructions for changing steering gear-TB/ALL.  

Code of Federal Regulations, 2010 CFR

...Instructions for changing steering gear-TB/ALL. 35.40-30 Section 35.40-30... Posting and Marking Requirements-TB/ALL. 35.40-30 Instructions for changing steering gearTB/ALL. Instructions in at least...

2010-10-01

343

Strong room-temperature easy-axis anisotropy in Tb2Fe17H3: An exception among R2Fe17 hydrides  

NASA Astrophysics Data System (ADS)

The iron-rich intermetallics R2Fe17 (where R is a rare-earth element) proved unamenable to anisotropy control via interstitial doping. There is only one precedent, Sm2Fe17N3-? (Sm2Fe17C3-?), where interstitial modification has stabilized an easy-axis anisotropy at all temperatures up to TC. All previous attempts to prepare a usable easy-axis R2Fe17 hydride have failed. Now we have succeeded in preparing a high-quality single-phase Tb2Fe17H3 single crystal, which has the required easy-axis anisotropy between 0 K and TC = 560 K. At T = 300 K, Tb2Fe17H3 has the spontaneous magnetic moment Ms of 22.5 ?B per formula unit and anisotropy field ?0Ha of 2.5 T. The main mechanism stabilizing the easy-axis anisotropy in hydrides is the same as in other similar compounds by way of boosting the leading crystal field parameter A20. Terbium is rather special in having the Stevens factors such that ?J < 0 and ?J > 0, which is why the easy-axis anisotropy in Tb2Fe17 hydrides is also assisted by the fourth-order parameter A40. This proves a decisive advantage over the compounds with R = Pr, Nd, Dy, or Ho where ?J < 0 and A40 is a hindrance.

Tereshina, E. A.; Drulis, H.; Skourski, Y.; Tereshina, I. S.

2013-06-01

344

HIV-Associated TB in An Giang Province, Vietnam, 20012004: Epidemiology and TB Treatment Outcomes  

PubMed Central

Background Mortality is high in HIV-infected TB patients, but few studies from Southeast Asia have documented the benefits of interventions, such as co-trimoxazole (CTX), in reducing mortality during TB treatment. To help guide policy in Vietnam, we studied the epidemiology of HIV-associated TB in one province and examined factors associated with outcomes, including the impact of CTX use. Methodology/Principal Findings We retrospectively abstracted data for all HIV-infected persons diagnosed with TB from 20012004 in An Giang, a province in southern Vietnam in which TB patients receive HIV counseling and testing. We used standard WHO definitions to classify TB treatment outcomes. We conducted multivariate analysis to identify risk factors for the composite outcome of death, default, or treatment failure during TB treatment. From 20012004, 637 HIV-infected TB patients were diagnosed in An Giang. Of these, 501 (79%) were male, 321 (50%) were aged 2534 years, and the most common self-reported HIV risk factor was sex with a commercial sex worker in 221 (35%). TB was classified as smear-positive in 531 (83%). During TB treatment, 167 (26%) patients died, 9 (1%) defaulted, and 6 (1%) failed treatment. Of 454 patients who took CTX, 116 (26%) had an unsuccessful outcome compared with 33 (70%) of 47 patients who did not take CTX (relative risk, 0.4; 95% confidence interval [CI], 0.30.5). Adjusting for male sex, rural residence, TB smear status and disease location, and the occurrence of adverse events during TB treatment in multivariate analysis, the benefit of CTX persisted (adjusted odds ratio for unsuccessful outcome 0.1; CI, 0.10.3). Conclusions/Significance In An Giang, Vietnam, HIV-associated TB was associated with poor TB treatment outcomes. Outcomes were significantly better in those taking CTX. This finding suggests that Vietnam should consider applying WHO recommendations to prescribe CTX to all HIV-infected TB patients. PMID:17551587

Thuy, Trinh Thanh; Shah, N. Sarita; Anh, Mai Hoang; Nghia, Do Trong; Thom, Duong; Linh, Truong; Sy, Dinh Ngoc; Duong, Bui Duc; Chau, Luu Thi Minh; Mai, Phung Thi Phuong; Wells, Charles D.; Laserson, Kayla F.; Varma, Jay K.

2007-01-01

345

46 CFR 30.10-61 - Rivers-TB/R.  

Code of Federal Regulations, 2010 CFR

... 1 2010-10-01 2010-10-01 false Rivers-TB/R. 30.10-61 Section 30.10-61 Shipping COAST GUARD...GENERAL PROVISIONS Definitions 30.10-61 RiversTB/R. Under this designation shall be included all tank vessels...

2010-10-01

346

46 CFR 30.10-45 - Ocean-TB/O.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Ocean-TB/O. 30.10-45 Section 30...PROVISIONS Definitions 30.10-45 OceanTB/O. Under this designation...vessels normally navigating the waters of any ocean or the Gulf of Mexico more than 20...

2013-10-01

347

46 CFR 30.10-45 - Ocean-TB/O.  

...2014-10-01 2014-10-01 false Ocean-TB/O. 30.10-45 Section 30...PROVISIONS Definitions 30.10-45 OceanTB/O. Under this designation...vessels normally navigating the waters of any ocean or the Gulf of Mexico more than 20...

2014-10-01

348

46 CFR 30.10-45 - Ocean-TB/O.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Ocean-TB/O. 30.10-45 Section 30...PROVISIONS Definitions 30.10-45 OceanTB/O. Under this designation...vessels normally navigating the waters of any ocean or the Gulf of Mexico more than 20...

2011-10-01

349

46 CFR 30.10-45 - Ocean-TB/O.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Ocean-TB/O. 30.10-45 Section 30...PROVISIONS Definitions 30.10-45 OceanTB/O. Under this designation...vessels normally navigating the waters of any ocean or the Gulf of Mexico more than 20...

2012-10-01

350

46 CFR 30.10-45 - Ocean-TB/O.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Ocean-TB/O. 30.10-45 Section 30...PROVISIONS Definitions 30.10-45 OceanTB/O. Under this designation...vessels normally navigating the waters of any ocean or the Gulf of Mexico more than 20...

2010-10-01

351

46 CFR 32.02-10 - Rails-TB/ALL.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Rails-TB/ALL. 32.02-10 Section 32... Safety Requirements 32.02-10 RailsTB/ALL. (a) All tank vessels...July 1, 1969, shall have efficient guard rails or bulwarks on decks and bridges....

2012-10-01

352

46 CFR 32.02-10 - Rails-TB/ALL.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Rails-TB/ALL. 32.02-10 Section 32... Safety Requirements 32.02-10 RailsTB/ALL. (a) All tank vessels...July 1, 1969, shall have efficient guard rails or bulwarks on decks and bridges....

2010-10-01

353

46 CFR 32.02-10 - Rails-TB/ALL.  

...2014-10-01 2014-10-01 false Rails-TB/ALL. 32.02-10 Section 32... Safety Requirements 32.02-10 RailsTB/ALL. (a) All tank vessels...July 1, 1969, shall have efficient guard rails or bulwarks on decks and bridges....

2014-10-01

354

46 CFR 32.02-10 - Rails-TB/ALL.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Rails-TB/ALL. 32.02-10 Section 32... Safety Requirements 32.02-10 RailsTB/ALL. (a) All tank vessels...July 1, 1969, shall have efficient guard rails or bulwarks on decks and bridges....

2013-10-01

355

46 CFR 32.02-10 - Rails-TB/ALL.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Rails-TB/ALL. 32.02-10 Section 32... Safety Requirements 32.02-10 RailsTB/ALL. (a) All tank vessels...July 1, 1969, shall have efficient guard rails or bulwarks on decks and bridges....

2011-10-01

356

Differential effects of two alleles of the dy locus on the pituitary-testicular axis of mice.  

PubMed

Testicular function was studied in vivo and in vitro in adult male dy/dy and dy2J/dy2J dystrophic mice. The results demonstrate that testicular function in dy/dy mice is more affected. The basal levels of pituitary hormones measured were normal in dystrophic mice, except for the presence of hyperprolactinemia in dy/dy mice. In dy/dy mice testicular weight was diminished and a deficient transduction of the gonadotropic signal is present in vivo, accompanied by reduced efficiency of 17-hydroxylase and 17-hydroxysteroid dehydrogenase. In dy2J/dy2J mice the signal transduction is normal and the reduction in enzyme efficiency is limited to 17-hydroxysteroid dehydrogenase. The in vitro HCG-induced increases in production of testosterone (T) and estradiol (E2) were reduced in dy/dy/mice, and the data indicate a reduction of enzyme activity rather than in efficiency. In dy21/dy21/mice, HCG-induced T synthesis was increased, HCG-induced E2 synthesis was normal, but basal media E2 levels were reduced, with the in vitro efficiency of aromatase being suppressed under both basal and HCG-stimulated conditions, when compared to their normal littermates. PMID:1301630

Amador, A G; Mayerhofer, A; Parkening, T A; Collins, T J; Bartke, A

1992-09-01

357

Redetermination of Dy3Ni from single-crystal X-ray data.  

PubMed

The classification of the title compound, tridysprosium nickel, into the Fe3C (or Al3Ni) structure type has been deduced from powder X-ray diffraction data with lattice parameters reported in a previous study [Lemaire & Paccard (1967 ?). Bull. Soc. Fr. Mineral. Cristallogr. 40, 311-315]. The current re-investigation of Dy3Ni based on single-crystal X-ray data revealed atomic positional parameters and anisotropic displacement parameters with high precision. The asymmetric unit consists of two Dy and one Ni atoms. One Dy atom has site symmetry .m. (Wyckoff position 4c) and is surrounded by twelve Dy and three Ni atoms. The other Dy atom (site symmetry 1, 8d) has eleven Dy and three Ni atoms as neighbours, forming a distorted Frank-Kasper polyhedron. The coordination polyhedron of the Ni atom (.m., 4c) is a tricapped trigonal prism formed by nine Dy atoms. PMID:24454015

Levytskyy, Volodymyr; Babizhetskyy, Volodymyr; Kotur, Bohdan; Smetana, Volodymyr

2013-10-26

358

Redetermination of Dy3Ni from single-crystal X-ray data  

PubMed Central

The classification of the title compound, tridysprosium nickel, into the Fe3C (or Al3Ni) structure type has been deduced from powder X-ray diffraction data with lattice parameters reported in a previous study [Lemaire & Paccard (1967 ?). Bull. Soc. Fr. Mineral. Cristallogr. 40, 311315]. The current re-investigation of Dy3Ni based on single-crystal X-ray data revealed atomic positional parameters and anisotropic displacement parameters with high precision. The asymmetric unit consists of two Dy and one Ni atoms. One Dy atom has site symmetry .m. (Wyckoff position 4c) and is surrounded by twelve Dy and three Ni atoms. The other Dy atom (site symmetry 1, 8d) has eleven Dy and three Ni atoms as neighbours, forming a distorted FrankKasper polyhedron. The coordination polyhedron of the Ni atom (.m., 4c) is a tricapped trigonal prism formed by nine Dy atoms. PMID:24454015

Levytskyy, Volodymyr; Babizhetskyy, Volodymyr; Kotur, Bohdan; Smetana, Volodymyr

2013-01-01

359

Percutaneous breast implant herniation: a rare complication of miliary TB.  

PubMed

We describe the case of a 46-year-old female patient treated for disseminated tuberculosis (TB) infection involving the lungs, urinary tract and skin. Following initiation of antituberculous therapy, the patient's right breast implant eroded through the overlying skin and was seen to be herniating through the resulting defect. The breast implant was removed under local anaesthetic and histological analysis of the resected tissue demonstrated granuloma formation consistent with periprosthetic TB. Wound healing following implant removal was poor and future breast augmentation surgery was only considered following completion of 12?months anti-TB treatment. This case constitutes the first report in the literature of percutaneous breast implant herniation resulting from periprosthetic infection with TB. A high index of suspicion is required to ensure early detection and timely management of TB and, in cases where periprosthetic pus aspirate is sterile, mycobacterial infection must be actively excluded. PMID:25568276

Dale, Adam P; Dedicoat, Martin J; Saleem, Tausif; Moran, Ed

2015-01-01

360

Effect of Dy/Nd double layer on coercivity in Nd-Fe-B thin films  

SciTech Connect

The Nd-Fe-B (t{sub NFB}?=?30?nm)/[Dy (t{sub Dy} nm)/Nd (t{sub Nd} nm)] (t{sub Dy/Nd}?=?20?nm) (thickness t{sub Dy}?=?010?nm) thin films were deposited on Al{sub 2}O{sub 3}(0001) substrate and subsequently in-situ annealed at 470?C. As-deposited Nd-Fe-B thin films with a highly perpendicular orientation of c-axis were deposited by introducing bcc-Mo(111) single crystal buffer layer. After post-annealing, the grain size of the Nd-Fe-B/Dy/Nd thin films with the t{sub Dy}?=?10?nm and t{sub Nd}?=?10?nm becomes large due to the Dy and the Nd atoms thermal diffusion, while DyFe{sub 2} and Dy oxide compounds are formed in Nd-Fe-B layers, which is confirmed by means of a combination of atomic force microscopy observation and X-ray diffraction measurement. The H{sub c} of Nd-Fe-B/Dy/Nd thin films with the t{sub Dy}?=?10?nm and t{sub Nd}?=?10?nm was approximately the same value of the Nd-Fe-B thin films without Dy/Nd double layer annealed at 470?C. On the other hand, H{sub c} is enhanced to be about 22.1?kOe in the annealed Nd-Fe-B/Dy/Nd films with the t{sub Dy}?=?0.8?nm and t{sub Nd}?=?19.2?nm.

Koike, K., E-mail: kkoike@yz.yamagata-u.ac.jp; Umezawa, J.; Ishikawa, H.; Ogawa, D.; Mizuno, Y.; Kato, H. [Department of Applied Mathematics and Physics, Yamagata University, Yonezawa 992-8510 (Japan); Miyazaki, T.; Ando, Y. [Department of Applied Physics, Tohoku University, Sendai, 980-8579 (Japan)

2014-05-07

361

Magnetic, electronic and optical properties of lanthanide hydrides, GdH2 and GdH3  

NASA Astrophysics Data System (ADS)

The structural, magnetic, electronic and optical properties as well as phase stabilities under pressure for GdH2 and GdH3 are investigated using density function theory. The non-magnetic (NM), ferromagnetic (FM) and antiferromagnetic (AFM) phases are considered for the total energy calculations. The magnetic phase is much more stable than the nonmagnetic phase both at ambient pressure and high pressure for the cubic GdH2 or hexagonal GdH3, but the antiferromagnetic phase is only slightly more stable than the ferromagnetic phase at ambient pressure in the two cases. With increasing pressure, the antiferromagnetic fcc GdH2 may transform to the ferromagnetic phase, while the antiferromagnetic hcp GdH3 keeps stable in the interesting pressure range. The pure theoretical calculations further indicate that there is a structural transition from hcp to fcc for GdH3 at about 9.8 GPa. In addition, the calculations of band structures and densities of states clearly show that the antiferromagnetic fcc GdH2 attributes to metal, whereas the antiferromagnetic hcp GdH3 attributes to semiconductor, but both have similar ionic-covalent bonding character. The semiconducting GdH3 may have a 1.55 eV fundamental band gap. Under the fundamental band gap, the complex dielectric function and refractive index are predicted for the hcp GdH3 in the whole energy range.

Kong, Bo; Zhang, Lin; Chen, Xiang-Rong; Deng, Ming-Sen; Cai, Ling-Cang; Ling-Hu, Rong-Feng

2013-09-01

362

In 1997, the maize gene tb1 was reported as the first domestication QTL to be cloned (4). tb1  

E-print Network

In 1997, the maize gene tb1 was reported as the first domestication QTL to be cloned (4). tb1, in addition to the two rice shattering genes, cloning of the wheat Q gene was reported (7). Q controls the chaff. A notable feature of this list of six domestica- tion genes is that five of the six encode

Forbes, Jeffrey

363

A Comparative Study of the Electronic and Magnetic Properties of Gd5Ge4 and Gd5Si4 Compounds  

NASA Astrophysics Data System (ADS)

We present a comparative study of electronic structure and magnetic properties of Gd5Si4 and Gd5Ge4 compounds using first principles full potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT) using the WIEN2k code. The local-spin density approximation with correlation energy (LSDA+U) method has been used as the exchange-correlation potential. The optimized lattice constants are in good agreement with the experimental data. The total and partial density of states (DOS) of Gd5Si4 and Gd5Ge4 show the difference in Si 3p-Gd 5d and Ge 4p-Gd 5d hybridization, which have an effective role in indirect exchange interaction. In addition, the magnetic moments of Gd, Si, and Ge atoms and the compounds are calculated to clarify the differences in the magnetic properties of these compounds.

Z. Momeni, Larimi; Amirabadizadeh, A.; Yazdani, A.; Arabi, H.

2014-12-01

364

Distribution of disialoganglioside GD2-antigen and binding of anti-GD2 antibodies on spheroids of neuroblastoma cell line.  

PubMed

The ganglioside GD2 is highly expressed on human tumors of neuroectodermal origin. We investigated by scanning electron microscopy the ganglioside GD2 distribution on the surface of spheroids of the neuroblastoma cell line SK-N-LO. About 50% of cells showed GD2 on the plasma membrane and the distribution of GD2 on most of these cells was heterogeneous, with more GD2 at the contact sites of the cells. The binding kinetics of the chimeric anti-GD2 antibody ch14.18 labelled with I-125 on spheroids (average diameter: 450 microns) was determined by gamma counting. Over 4 hours the antibody concentration was raised substantially but up to 24 hours there was only a very slow further increase. A clustered pattern of bound chimeric anti-GD2 antibody ch14.18 was found on a cross-section of the spheroid by autoradiography. PMID:9329622

Heiss, P; Bermatz, S; Wehnes, H; Heinzmann, U; Senekowitsch-Schmidtke, R

1997-01-01

365

Structure and magnetic properties of RCo7-xZrx (R=Y, Gd, Nd, or Ho, x=0-0.8)  

NASA Astrophysics Data System (ADS)

Alloys with the composition RCo7-xZrx (R=Y, Gd, Nd, or Ho, x=0-0.8) were synthesized and characterized in the temperature range from 10 to 1273 K and in fields up to 5 T. As with the R=Sm, Pr, or Er systems studied earlier in our laboratory, the effects of Zr doping on the stability of TbCu7 structure phase and changes in the magnetocrystalline anisotropy HA are observed in the systems in which the rare earth is Y, Gd, Nd, or Ho. Nearly single phase TbCu7 structure materials were formed in the as-cast alloys when x=0.1 and 0.2. In the case of R=Y or Gd, a large increase in HA (which is mainly contributed by Co sublattice) by Zr doping was observed. For R=Y, HA increases from 18 kOe for x=0 to 74 kOe for x=0.2 at 300 K and from 20 kOe for x=0 to 82 kOe for x=0.2 at 10 K. For R=Gd, HA increases from 35 kOe for x=0 to 140 kOe for x=0.2 at 300 K and to 182 kOe for x=0.2 at 10 K. In the case of R=Ho and Nd, the R-sublattice favors a planar anisotropy at room temperature, presumably due to the negative second order Stevens' coefficient. For R=Ho, the anisotropy changes from planar for x=0 to axial with HA60-70 kOe at 300 K when x=0.1 and 0.2. For R=Nd, HA is dominated by R sublattice which results in a planar anisotropy. Other magnetic properties such as magnetization, Curie temperature, and spin reorientation temperature for these alloys are presented.

Huang, M. Q.; Sankar, S. G.; Wallace, W. E.; McHenry, M. E.; Chen, Q.; Ma, B. M.

2000-05-01

366

Air Travel and TB: an airline perspective.  

PubMed

The commercial airline industry in the 21st century is a global business, able to transport large numbers of people to almost any part of the world within a few hours. There has long been concern in public health circles about the potential for transmission of communicable diseases, such as TB, on board aircraft. The recent threats from novel and emerging infectious diseases including SARS and pandemic flu has facilitated unprecedented levels of cooperation between international industry representatives, regulators and public health authorities in addressing the issues of air travel and communicable disease. This paper reviews the regulatory environment, ways in which the risks are mitigated through aspects of aircraft design, opportunities for prevention by identifying individuals who may be suffering from a communicable disease prior to flight and the approach used in managing suspected cases of communicable disease on board aircraft. PMID:20478517

Dowdall, Nigel P; Evans, Anthony D; Thibeault, Claude

2010-03-01

367

Quantum-cutting of KYF4:Tb3+,Yb3+ under multiple excitations with high Tb3+ concentration  

NASA Astrophysics Data System (ADS)

A new kind of quantum-cutting (QC) phosphor KYF4:Tb3+,Yb3+ was prepared by the sol-gel method by using trifluoroacetic acid as a fluorine source. Tb3+-doped samples represent high quenching concentration as 15%. The near-infrared fluorescence spectra of Tb3+&Yb3+ co-doped samples with high Tb3+ concentration (15%) indicate that QC can occur under different excitations of Tb3+, and the 7F6 ? 5D3 excitation (374 nm) is more effective than 7F6 ? 5D4 excitation (483 nm). Through the lifetime measurement, the maximum of QC efficiency (?QE) under 7F6 ? 5D4 and 7F6 ? 5D3 excitations are calculated as 161% and 150%, respectively. The results all above infer that this phosphor can make use of high-energy photons of several wavelengths and may raise the conversion efficiency of solar cells greatly.

Lin, Lin; Lin, Hui; Wang, Zhezhe; Chen, Jixing; Huang, Ruijie; Rao, Xin; Feng, Zhuohong; Zheng, Zhiqiang

2014-04-01

368

Excitation process of the Tb emission center in a ZnS:Tb,F thin-film electroluminescent device  

NASA Astrophysics Data System (ADS)

The excitation spectrum for terbium (Tb) emission in a ZnS:Tb,F film varies sensitively with Tb concentration, the amount of fluorine (F) relative to Tb, post-deposition annealing, and the temperature of measurement. There are at least three kinds of channels for the excitation of Tb3+ ions; namely, resonant energy transfer from the recombination of an electron-hole pair, direct transitions between the 4f 8 configuration states of a Tb3+ ion, and the indirect excitation via lattice defects. A rapid quenching of photoluminescence (PL) is observed above 0.2 at. % of the Tb concentration in the case of indirect excitation of energy transfer. The PL intensity additionally reduced in the presence of F- ions, even at the same Tb concentration. In contrast, when the Tb3+ ions are directly excited to the 5D3 energy state, the PL intensity increases proportionally up to a maximum of about 2 at. %. The luminance of the electroluminescent device behaves in the same way. Another excitation band is found in an energy region slightly below the band gap of ZnS, and is identified as due to Tb-related complexes associated with sulfur interstitials. The PL characteristics obtained with three excitation channels are also compared with the electroluminescence (EL) characteristics, concerning the effects of post-deposition annealing and measurement temperature. The excitation mechanism of electroluminescence can be explained on the basis of the direct impact model, and the real nature of the energy transfer process is also discussed.

Mikami, Akiyoshi; Ogura, Takashi; Taniguchi, Koji; Yoshida, Masaru; Nakajima, Shigeo

1988-10-01

369

Thermochemical investigations in the system CdGd  

PubMed Central

Vapour pressure measurements were performed in terms of a non-isothermal isopiestic method to determine vapour pressures of Cd in the system CdGd between 693 and 1045K. From these results thermodynamic activities of Cd were derived as a function of temperature for the composition range 5286at.% Cd. By employing an adapted GibbsHelmholtz equation, partial molar enthalpies of mixing of Cd were obtained for the corresponding composition range, which were used to convert the activity values of Cd to a common average sample temperature of 773K. The relatively large variation of the activity across the homogeneity ranges of the phases Cd2Gd and Cd45Gd11 indicates that they probably belong to the most stable intermetallic compounds in this system. An activity value of Gd for the two phase field Cd6Gd+L was available from literature and served as an integration constant for a GibbsDuhem integration. Integral Gibbs energies are presented between 51 and 100at.% Cd at 773K, referred to Cd(l) and ?-Gd(s) as standard states. Gibbs energies of formation for the exact stoichiometric compositions of the phases Cd58Gd13, Cd45Gd11, Cd3Gd and Cd2Gd were obtained at 773K as about ?19.9, ?21.1, ?24.8, and ?30.0kJgatom?1, respectively. PMID:25328283

Reichmann, Thomas L.; Ganesan, Rajesh; Ipser, Herbert

2014-01-01

370

Laser-induced magnetization dynamics of lanthanide-doped permalloy thin films.  

PubMed

We investigate the effect of Ho, Dy, Tb, and Gd impurities on the femtosecond laser-induced magnetization dynamics of thin Permalloy films using the time-resolved magneto-optical Kerr effect. Varying the amount of Ho, Dy, Tb content from 0% to 8%, we observe a gradual change of the characteristic demagnetization time constant from approximately 60 to approximately 150 fs. In contrast, Gd concentrations up to 15% do not influence the time scale of the initial photoinduced magnetization loss. We propose a demagnetization mechanism that relies on strong magnetic inertia of the rare-earth dopant which stabilizes the ferrimagnetic ordering and thereby delays the demagnetization. PMID:19392235

Radu, I; Woltersdorf, G; Kiessling, M; Melnikov, A; Bovensiepen, U; Thiele, J-U; Back, C H

2009-03-20

371

Susceptibility of rare earth bromates between 1 and 4.2 K  

NASA Astrophysics Data System (ADS)

AC magneitic susceptibilities measured between 1 and 4.2 K are reported for a series of rare earth bromate hydrates, RE(BrO3)3 9H2O, for the rare earths Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Yb. Results for Pr, Tb, Dy, and Er are in good agreement with a previous determination. New results are reported for Nd, Sm, Gd, Ho, and Yb, some of which show interesting differences from the structurally similar rare earth ethylsulfates and anhydrous trichlorides.

Xu, Jingchun; Corruccini, L. R.

1987-06-01

372

Comparisons of the Odd-Even Staggering Patterns Between the Ba-Dy Region with 88 Neutrons and ra Isotopes with 88 Protons  

NASA Astrophysics Data System (ADS)

Useful information about the shape transitions of even-even isotones 144Ba, 146Ce, 148Nd, 150Sm, 152Gd, 154Dy with 88 neutrons and 218-226Ra isotopes with 88 protons are obtained from the ratios of E(4+1)/E(2^+_1) as a function of neutron number N or proton number Z and the relations E(I+1)/E(2^+_1) and r((I+2)/I) as a function of the angular momentum I. Interacting Boson Model (IBM-1), Bohr-Mottelson Model (BM) and Interacting Vector Boson Model (IVBM) have been employed to study the energy levels for the ground and octupole bands of the above nuclei. The best input parameters for the above approaches which lead to the best fit to experimental data are determined. The ?I = 1 staggering (odd-even staggering) in octupole bands of the studied nuclei is found to exhibit a "beat" behavior as a function of angular momentum I. Comparisons of the displacement energies ?E(I) and the staggering factor ?E1, ?(I) are presented between the Ba-Dy region with 88 neutrons and Ra isotopes with 88 protons.

Mheemeed, Ahmed K.

2013-09-01

373

High resolution magnetic resonance imaging of the brain in the dy\\/dy mouse with merosin-deficient congenital muscular dystrophy  

Microsoft Academic Search

Magnetic resonance imaging (MRI) abnormalities in the cerebral white matter are a consistent feature of merosin-deficient human congenital muscular dystrophy, a disease caused by a primary defect in the expression of the laminin ?2 chain of merosin. To investigate the relationship between imaging changes and merosin deficiency we undertook a MRI study in the dy\\/dy mouse, an animal model for

David J. Dubowitz; J. Michael Tyszka; Caroline A. Sewry; Rex A. Moats; Miriam Scadeng; Victor Dubowitz

2000-01-01

374

Antigen-Specific Interferon-Gamma Responses and Innate Cytokine Balance in TB-IRIS  

PubMed Central

Background Tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) remains a poorly understood complication in HIV-TB patients receiving antiretroviral therapy (ART). TB-IRIS could be associated with an exaggerated immune response to TB-antigens. We compared the recovery of IFN? responses to recall and TB-antigens and explored in vitro innate cytokine production in TB-IRIS patients. Methods In a prospective cohort study of HIV-TB co-infected patients treated for TB before ART initiation, we compared 18 patients who developed TB-IRIS with 18 non-IRIS controls matched for age, sex and CD4 count. We analyzed IFN? ELISpot responses to CMV, influenza, TB and LPS before ART and during TB-IRIS. CMV and LPS stimulated ELISpot supernatants were subsequently evaluated for production of IL-12p70, IL-6, TNF? and IL-10 by Luminex. Results Before ART, all responses were similar between TB-IRIS patients and non-IRIS controls. During TB-IRIS, IFN? responses to TB and influenza antigens were comparable between TB-IRIS patients and non-IRIS controls, but responses to CMV and LPS remained significantly lower in TB-IRIS patients. Production of innate cytokines was similar between TB-IRIS patients and non-IRIS controls. However, upon LPS stimulation, IL-6/IL-10 and TNF?/IL-10 ratios were increased in TB-IRIS patients compared to non-IRIS controls. Conclusion TB-IRIS patients did not display excessive IFN? responses to TB-antigens. In contrast, the reconstitution of CMV and LPS responses was delayed in the TB-IRIS group. For LPS, this was linked with a pro-inflammatory shift in the innate cytokine balance. These data are in support of a prominent role of the innate immune system in TB-IRIS. PMID:25415590

Goovaerts, Odin; Jennes, Wim; Massinga-Loemb, Marguerite; Ceulemans, Ann; Worodria, William; Mayanja-Kizza, Harriet; Colebunders, Robert; Kestens, Luc

2014-01-01

375

GD SDR Automatic Gain Control Characterization Testing  

NASA Technical Reports Server (NTRS)

The General Dynamics (GD) S-Band software defined radio (SDR) in the Space Communications and Navigation (SCAN) Testbed on the International Space Station (ISS) will provide experimenters an opportunity to develop and demonstrate experimental waveforms in space. The GD SDR platform and initial waveform were characterized on the ground before launch and the data will be compared to the data that will be collected during on-orbit operations. A desired function of the SDR is to estimate the received signal to noise ratio (SNR), which would enable experimenters to better determine on-orbit link conditions. The GD SDR does not have an SNR estimator, but it does have an analog and a digital automatic gain control (AGC). The AGCs can be used to estimate the SDR input power which can be converted into a SNR. Tests were conducted to characterize the AGC response to changes in SDR input power and temperature. This purpose of this paper is to describe the tests that were conducted, discuss the results showing how the AGCs relate to the SDR input power, and provide recommendations for AGC testing and characterization.

Nappier, Jennifer M.; Briones, Janette C.

2013-01-01

376

Magnetic properties of Dy2Ti2O7  

NASA Technical Reports Server (NTRS)

Measurements were made of the magnetization, differential magnetic susceptibility, and magnetic entropy of powered samples of Dy2Ti2O7. The saturation magnetic moment is 4.7 + or - 0.2 Bohr magnetons per Dy ion, instead of 10 as predicted by Hund's rules. A temperature-independent magnetization is observed in the saturation region. Absolute values of magnetic entropy have been obtained for temperatures from 1.25 to 20 K, in applied fields up to 10.4 tesla. The magnetic entropy approaches a maximum value consistent with a ground-state multiplicity of 2. Low field magnetization and differential susceptibility data show a transition to antiferromagnetism near 1.35 K. A construction of the magnetic specific heat from the zero field entropy shows an anomaly near the same temperature.

Flood, D. J.

1973-01-01

377

de = (dx, dy, d) e = r de (1)  

E-print Network

, dy, d) r ^P e e = r ? de (1) ^Pc ^Pc = ^P - e (2) 4. 4NDT . . 0.025[sec] 1. 2. 3. . 4. 5. NDT[4] NDT ( .4- ) (x, y)T NDT 1. k (xk1, ..., xkNk ) 2. k qk = 1 Nk Nk i=1 xki 3. k k = 1 Nk Nk i=1 (xki - qk] 11 6. NDT [1] P.Besl and N.Mckay. A method for registration of 3- d shapes. IEEE Transactions

Ohya, Akihisa

378

High-field magnetization of Dy2O3  

NASA Technical Reports Server (NTRS)

The magnetization of powdered samples of Dy2O3 has been measured at temperatures between 1.45 and 4.2 K, in applied magnetic fields ranging to 70 kilogauss. A linear dependence of magnetization on applied field is observable in the high-field region, the slope of which is independent of temperature over the range investigated. The extrapolated saturation magnetic moment is about 2.77 Bohr magnetons per ion.

Flood, D. J.

1974-01-01

379

High-field magnetization of Dy2O3  

NASA Technical Reports Server (NTRS)

The magnetization of powdered samples of Dy2O3 has been measured at temperatures between 1.45 deg and 4.2 K, in applied magnetic fields ranging to 7 Teslas. A linear dependence of magnetization on applied field is observable in high field region, the slope of which is independent of temperature over the range investigated. The extrapolated saturation magnetic moment is 2.77 + or - 0.08 Bohr magnetons per ion.

Flood, D. J.

1974-01-01

380

Partial laminin alpha2 chain restoration in alpha2 chain-deficient dy/dy mouse by primary muscle cell culture transplantation  

PubMed Central

Laminin-2 is a component of skeletal and cardiac basal lamina expressed in normal mouse and human. Laminin alpha2 chain (LAMA2), however, is absent from muscles of some congenital muscular dystrophy patients and the dystrophia muscularis (dy/dy) mouse model. LAMA2 restoration was investigated following cell transplantation in vivo in dy/dy mouse. Allogeneic primary muscle cell cultures expressing the beta- galactosidase transgene under control of a muscular promoter, or histocompatible primary muscle cell cultures, were transplanted into dy/dy mouse muscles. FK506 immunosuppression was used in noncompatible models. All transplanted animals expressed LAMA2 in these immunologically-controlled models, and the degrees of LAMA2 restoration were shown to depend on the age of the animal at transplantation, on muscle pretreatment, and on duration time after transplantation in some cases. LAMA2 did not always colocalize with new or hybrid muscle fibers formed by the fusion of donor myoblasts. LAMA2 deposition around muscle fibers was often segmental and seemed to radiate from the center to the periphery of the injection site. Allogeneic conditionally immortalized pure myogenic cells expressing the beta-galactosidase transgene were characterized in vitro and in vivo. When injected into FK506- immunosuppressed dy/dy mice, these cells formed new or hybrid muscle fibers but essentially did not express LAMA2 in vivo. These data show that partial LAMA2 restoration is achieved in LAMA2-deficient dy/dy mouse by primary muscle cell culture transplantation. However, not all myoblasts, or myoblasts alone, or the muscle fibers they form are capable of LAMA2 secretion and deposition in vivo. PMID:8601607

1996-01-01

381

Radioactivity measurements of 153Gd pellet sources by calorimetric methods  

Microsoft Academic Search

The thermal power generation per 37 MBq (1 mCi) of 153Gd is 0.839 muW. The activity of a sealed 153Gd source can be determined by absorbing all radiations within a calorimeter to be converted into the thermal power. Sources are sintered pellets (3 mm diameter, 2 mm thickness) of Gd2O3.Al2O3 which are encapsulated in titanium capsules of 7 mm diameter

Tsuguo Genka; Tsuyoshi Imahashi

1992-01-01

382

Synthesis and characterization of Gd(OH) 3 nanobundles  

Microsoft Academic Search

Gd(OH)3 nanobundles, which consisted of bundle-like nanorods, have been prepared through a simple and facile hydrothermal method. The crystal, purity, morphology and structural features of Gd(OH)3 nanobundles are investigated by powder X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and energy dispersive X-ray (EDX). A possible formation mechanism of Gd(OH)3 nanobundles is

Yidong Yin; Guangyan Hong

2006-01-01

383

Stability and collapse of fermions in a binary dipolar boson-fermion 164Dy-161Dy mixture  

NASA Astrophysics Data System (ADS)

We suggest a time-dependent mean-field hydrodynamic model for a binary dipolar boson-fermion mixture to study the stability and collapse of fermions in the 164Dy-161Dy mixture. The condition of stability of the dipolar mixture is illustrated in terms of phase diagrams. A collapse is induced in a disk-shaped stable binary mixture by jumping the interspecies contact interaction from repulsive to attractive by the Feshbach resonance technique. The subsequent dynamics is studied by solving the time-dependent mean-field model including three-body loss due to molecule formation in boson-fermion and boson-boson channels. Collapse and fragmentation in the fermions after subsequent explosions are illustrated. The anisotropic dipolar interaction leads to anisotropic fermionic density distribution during collapse. This study is carried out in three-dimensional space using realistic values of dipolar and contact interactions.

Adhikari, S. K.

2013-10-01

384

Properties of alginate fiber spun-dyed with fluorescent pigment dispersion.  

PubMed

Spun-dyed alginate fiber was prepared by the spun-dyeing method with the mixture of fluorescent pigment dispersion and sodium alginate fiber spinning solution, and its properties were characterized by SEM, TGA, DSC, and XRD. The results indicate that fluorescent pigment dispersion prepared with esterified poly (styrene-alt maleic acid) had excellent compatibility with sodium alginate fiber spinning solution, and small amount of fluorescent pigment could reduce the viscosity of spun-dyed spinning solutions. SEM photo of spun-dyed alginate fiber indicated that fewer pigment particles deposited on its surface. TGA, DSC, and XRD results suggested that thermal properties and crystal phase of spun-dyed alginate fibers had slight changes compared to the original alginate fibers. The fluorescence intensity of spun-dyed alginate fiber reached its maximum when the content of fluorescent pigment was 4%. The spun-dyed alginate fiber showed excellent rubbing and washing fastness. PMID:25542119

Wang, Ping; Tawiah, Benjamin; Tian, Anli; Wang, Chunxia; Zhang, Liping; Fu, Shaohai

2015-03-15

385

Nanoscale confinement of all-optical switching in TbFeCo using plasmonic antennas  

E-print Network

All-optical switching (AOS) of magnetic domains by femtosecond laser pulses was first observed in the transition metal-rare earth (TM-RE) alloy GdFeCo1-5; this phenomenon demonstrated the potential for optical control of magnetism for the development of ever faster future magnetic recording technologies. The technological potential of AOS has recently increased due to the discovery of the same effect in other materials, including RE-free magnetic multilayers6,7. However, to be technologically meaningful, AOS must compete with the bit densities of conventional storage devices, restricting optically-switched magnetic areas to sizes well below the diffraction limit. Here, we demonstrate reproducible and robust all-optical switching of magnetic domains of 53 nm size in a ferrimagnetic TbFeCo alloy using gold plasmonic antenna structures. The confined nanoscale magnetic reversal is imaged around and beneath plasmonic antennas using x-ray resonant holographic imaging. Our results demonstrate the potential of future...

Liu, TianMin; Reid, Alexander H; Savoini, Matteo; Wu, Xiaofei; Koene, Benny; Granitzka, Patrick; Graves, Catherine; Higley, Daniel; Chen, Zhao; Razinskas, Gary; Hantschmann, Markus; Scherz, Andreas; Sthr, Joachim; Tsukamoto, Arata; Hecht, Bert; Kimel, Alexey V; Kirilyuk, Andrei; Rasing, Theo; Drr, Hermann A

2014-01-01

386

46 CFR 32.75-1 - Application-TB/ALL.  

Code of Federal Regulations, 2010 CFR

...EQUIPMENT, MACHINERY, AND HULL REQUIREMENTS Hull Requirements for Wood Hull Tank Vessels Constructed Prior to November 10, 1936 32.75-1 ApplicationTB/ALL. All wood hull tank vessels, the construction or conversion of which was...

2010-10-01

387

46 CFR 32.75-1 - Application-TB/ALL.  

Code of Federal Regulations, 2012 CFR

...EQUIPMENT, MACHINERY, AND HULL REQUIREMENTS Hull Requirements for Wood Hull Tank Vessels Constructed Prior to November 10, 1936 32.75-1 ApplicationTB/ALL. All wood hull tank vessels, the construction or conversion of which was...

2012-10-01

388

46 CFR 32.75-1 - Application-TB/ALL.  

...EQUIPMENT, MACHINERY, AND HULL REQUIREMENTS Hull Requirements for Wood Hull Tank Vessels Constructed Prior to November 10, 1936 32.75-1 ApplicationTB/ALL. All wood hull tank vessels, the construction or conversion of which was...

2014-10-01

389

46 CFR 32.75-1 - Application-TB/ALL.  

Code of Federal Regulations, 2013 CFR

...EQUIPMENT, MACHINERY, AND HULL REQUIREMENTS Hull Requirements for Wood Hull Tank Vessels Constructed Prior to November 10, 1936 32.75-1 ApplicationTB/ALL. All wood hull tank vessels, the construction or conversion of which was...

2013-10-01

390

Disparities in HIV/AIDS, Viral Hepatitis, STDs, and TB  

MedlinePLUS

... and TB Health Disparities Social Determinants of Health African Americans/Blacks American Indians/Alaska Natives Asians Hispanics/Latinos ... Social Determinants of Health (SDH). More Popular Links African Americans Overview of health disparities found in black communities ...

391

NLM Directors Comments Transcript - TB and Sherlock Holmes  

MedlinePLUS

... why sanitariums originally were located in non-urban, tree-lined neighborhoods where the air quality was better ... two billion persons, or one-third of the worlds population, have a latent TB infection, which may ...

392

Tb/Na tobermorite: Thermal behaviour and high temperature products  

SciTech Connect

By heating a sample of Tb/Na tobermorite we obtained a phase which was identified through its X-ray diffraction (XRD) pattern, as terbium silicate apatite. Subsequently this compound has been directly prepared by solid state reaction and we carried out a structural refinement from XRD data in space group P6{sub 3}/m obtaining cell parameters a=9.39199(4) A and c=6.84041(5) A. Terbium silicate apatite heated in melted NaF led to Tb{sub 4}O{sub 7} crystals. - Graphical Abstract: By heating over 900 deg. C Tb/Na tobermorite a terbium silicate apatite was obtained. The same product has been independently prepared and structurally characterized from powder diffraction data. Attempts of crystallizing terbium silicate apatite from melted NaF led to Tb{sub 4}O{sub 7} crystals.

Garra, Walter [Dipartimento di Chimica e Chimica Industriale, Universita di Pisa, via Risorgimento, 35, 56126 Pisa (Italy); Marchetti, Fabio, E-mail: fama@dcci.unipi.i [Dipartimento di Chimica e Chimica Industriale, Universita di Pisa, via Risorgimento, 35, 56126 Pisa (Italy); Merlino, Stefano [Dipartimento di Scienze della Terra, Universita di Pisa, via S. Maria, 53, 56126 Pisa (Italy)

2009-06-15

393

HIV Screening among TB Patients and Co-Trimoxazole Preventive Therapy for TB/HIV Patients in Addis Ababa: Facility Based Descriptive Study  

PubMed Central

Background Collaborative TB/HIV management is essential to ensure that HIV positive TB patients are identified and treated appropriately, and to prevent tuberculosis (TB) in HIV positive patients. The purpose of this study was to assess HIV case finding among TB patients and Co-trimoxazole Preventive Therapy (CPT) for HIV/TB patients in Addis Ababa. Methods A descriptive cross-sectional, facility-based survey was conducted between June and July 2011. Data was collected by interviewing 834 TB patients from ten health facilities in Addis Ababa. Both descriptive and inferential statistics were used to summarize and analyze findings. Results The proportion of TB patients who (self reported) were offered for HIV test, tested for HIV and tested HIV positive during their anti-TB treatment follow-up were; 87.4%, 69.4% and 20.2%; respectively. Eighty seven HIV positive patients were identified, who knew their status before diagnosed for the current TB disease, bringing the cumulative prevalence of HIV among TB patients to 24.5%. Hence, the proportion of TB patients who knew their HIV status becomes 79.9%. The study revealed that 43.6% of those newly identified HIV positives during anti-TB treatment follow-up were actually treated with CPT. However, the commutative proportion of HIV positive TB patients who were ever treated with CPT was 54.4%; both those treated before the current TB disease and during anti-TB treatment follow-up. Conclusions HIV case finding among TB patients and provision of CPT for TB/HIV co-infected patients needs boosting. Hence, routine offering of HIV test and provision of CPT for PLHIV should be strengthened in-line with the national guidelines. PMID:24498278

Denegetu, Amenu Wesen; Dolamo, Bethabile Lovely

2014-01-01

394

Polarization enhancement and ferroelectric switching enabled by interacting magnetic structures in DyMnO3 thin films  

PubMed Central

The mutual controls of ferroelectricity and magnetism are stepping towards practical applications proposed for quite a few promising devices in which multiferroic thin films are involved. Although ferroelectricity stemming from specific spiral spin ordering has been reported in highly distorted bulk perovskite manganites, the existence of magnetically induced ferroelectricity in the corresponding thin films remains an unresolved issue, which unfortunately halts this step. In this work, we report magnetically induced electric polarization and its remarkable response to magnetic field (an enhancement of ~800% upon a field of 2 Tesla at 2?K) in DyMnO3 thin films grown on Nb-SrTiO3 substrates. Accompanying with the large polarization enhancement, the ferroelectric coercivity corresponding to the magnetic chirality switching field is significantly increased. A picture based on coupled multicomponent magnetic structures is proposed to understand these features. Moreover, different magnetic anisotropy related to strain-suppressed GdFeO3-type distortion and Jahn-Teller effect is identified in the films. PMID:24291803

Lu, Chengliang; Dong, Shuai; Xia, Zhengcai; Luo, Hui; Yan, Zhibo; Wang, Haowen; Tian, Zhaoming; Yuan, Songliu; Wu, Tao; Liu, Junming

2013-01-01

395

Synthesis and densification behaviour of magnesium aluminate spinel: Effect of Dy 2O 3  

Microsoft Academic Search

Magnesium aluminate spinels have been developed by reaction sintering of calcined alumina and calcined magnesia and its densification behaviour was studied in presence of Dy2O3. Green bar made from stoichiometric spinel composition with and without Dy2O3 were subjected to dilatometric study, densification study and microstructural evaluation by SEM. It was found that Dy2O3 additive does not have significant effect on

H. S. Tripathi; S. Singla; A. Ghosh

2009-01-01

396

The Spectrum Near Maximum Light of the Unusual R Coronae Borealis Variable DY Persei  

Microsoft Academic Search

DY Per was confirmed photometrically as an R CrB variable by Alksnis in 1994. Spectra near maximum light show the high-speed ejection of matter (sodium at -174 km\\/sec in DY Per) characteristic of many of these variable stars. Moderate hydrogen deficiency may also be present. DY Per is remarkable in having a temperature many hundreds of degrees lower than most

P. C. Keenan; C. Barnbaum

1997-01-01

397

Magnetic structure of Tb-Fe films with an artificially layered structure  

SciTech Connect

The magnetic structure of Tb-Fe films with an artificially layered structure has been investigated by measuring the temperature dependence of the magnetization of the films. Ferrimagnetic coupling between Tb and Fe through the interface was explicitly observed up to about 9-A Tb and 10-A Fe layers. Films with thinner Tb and Fe layers than these thicknesses are composed of only ferrimagnetically coupled Tb-Fe regions. Films with thicker layers of Tb and Fe are composed of ferrimagnetically coupled Tb-Fe, ferromagnetic Fe, ferromagnetic Tb, and/or magnetically compensated Tb regions. The Tb-Fe films exhibit various temperature dependencies of the magnetization corresponding to these magnetic structures.

Yamauchi, K.; Habu, K.; Sato, N.

1988-11-15

398

Far-infrared spectroscopy of TbPO4  

Microsoft Academic Search

A direct spectroscopic investigation has been carried out of the low-lying crystal-field states of the lowest J manifold of Tb3+, 7F6 in single crystals of TbPO4, at 4.2 K. The energies and compositions of these states are of interst as a basis for understanding the subsequent phase transitions which occur as the temperature is lowered: a Jahn-Teller distortion at 3.5

J. F. Lewis; G. A. Prinz

1974-01-01

399

TB and HIV Therapeutics: Pharmacology Research Priorities  

PubMed Central

An unprecedented number of investigational drugs are in the development pipeline for the treatment of tuberculosis. Among patients with tuberculosis, co-infection with HIV is common, and concurrent treatment of tuberculosis and HIV is now the standard of care. To ensure that combinations of anti-tuberculosis drugs and antiretrovirals are safe and are tested at doses most likely to be effective, selected pharmacokinetic studies based on knowledge of their metabolic pathways and their capacity to induce or inhibit metabolizing enzymes of companion drugs must be conducted. Drug interaction studies should be followed up by evaluations in larger populations to evaluate safety and pharmacodynamics more fully. Involving patients with HIV in trials of TB drugs early in development enhances the knowledge gained from the trials and will ensure that promising new tuberculosis treatments are available to patients with HIV as early as possible. In this review, we summarize current and planned pharmacokinetic and drug interaction studies involving investigational and licensed tuberculosis drugs and antiretrovirals and suggest priorities for tuberculosis-HIV pharmacokinetic, pharmacodynamic, and drug-drug interaction studies for the future. Priority studies for children and pregnant women with HIV and tuberculosis co-infection are briefly discussed. PMID:22829999

Dooley, Kelly E.; Kim, Peter S.; Williams, Sharon D.; Hafner, Richard

2012-01-01

400

Magnetic properties of the hexagonal DyCo4Al compound  

NASA Astrophysics Data System (ADS)

The DyCo4Al compound crystallises in the hexagonal CaCu5-type structure (S.G. P6/mmm), Al atoms exclusively occupying the 3g crystallographic site of the structure. DyCo4Al is ferrimagnetic, and remarkable changes in the magnetic properties are observed with respect to DyCo5. Al substitution for Co causes a drastic reduction of the Curie temperature, from ~970K in DyCo5 to 479(5)K in DyCo4Al. This reduction is accompanied by an important increase of the saturation magnetisation at 4K: from 0.7?B/f.u. for DyCo5 up to 4.9?B/f.u. for DyCo4Al. The compensation temperature Tcomp is close to 300K, while Tcomp=124K in DyCo5. These phenomena are linked to a decrease of the mean Co magnetic moment. Thermomagnetic measurements have evidenced a spin reorientation transition at TSR~400K. A powder neutron diffraction investigation was performed, and the Rietveld refinements led to the characterisation of the magnetic phase diagram of DyCo4Al in the whole ordered temperature range. The Co magnetic moments are typically about 1.2?B.

Klosek, V.; Zlotea, C.; Isnard, O.

2004-07-01

401

Luminescent properties of Dy 3+ doped SrMoO 4 phosphor  

Microsoft Academic Search

Trivalent dysprosium ions (Dy3+) doped strontium molybdate (SrMoO4) phosphors were synthesized by solid-state reaction and their photoluminescence (PL) properties were investigated. X-ray powder diffraction (XRD) analysis confirmed the formation of SrMoO4:Dy3+. PL measurements indicated that the phosphor exhibited intense emission at 482, 490 (4F9\\/2?6H15\\/2) and 575nm (4F9\\/2?6H13\\/2) under UV excitation. The effect of the doping concentration of Dy3+in SrMoO4:Dy3+ on

Xu Li; Li Guan; Mingsheng Sun; Haiyan Liu; Zhiping Yang; Qinglin Guo; Guangsheng Fu

2011-01-01

402

TbOF complex centers in ZnS thin-film electroluminescent devices  

NASA Astrophysics Data System (ADS)

The effect of oxygen doping in ZnS:TbF thin-film electroluminescent (EL) devices has been studied. We concluded that the TbOF complex center is more efficient than the TbF complex center in ZnS thin-film EL devices. The improvement is attributed to the decreased nonradiative emission process of Tb and/or enlarged lattice distortions which generate electron-hole pairs efficiently at the Tb excitation site.

Okamoto, Kenji; Yoshimi, Takuya; Miura, Shoshin

1988-08-01

403

Development of magnetic order in the TbNi(Al,In) series and magnetocrystalline anisotropy in TbTX compounds  

NASA Astrophysics Data System (ADS)

We report on the magnetic structures in the TbNiAl1-xInx compounds as determined by powder neutron diffraction. These compounds belong to a large family of ternary rare-earth intermetallics crystallizing in the ZrNiAl-type hexagonal structure. All studied compounds order magnetically with magnetic structures characterized by k1=(0,0,0) and k2=((1)/(2),0,(1)/(2)) propagation vectors and magnetic moments aligned along or perpendicular to the hexagonal c axis. The magnetocrystalline anisotropy changes from uniaxial in the In-poor compounds (x?0.4) to planar in the In-rich compounds (x?0.5). The change of magnetocrystalline anisotropy type is a consequence of the development of structural parameters in the studied series. The Tb moments are oriented along the c axis when the nearest Tb-Tb distances between the planes are large compared to those within the planes, whereas Tb moments lie within the basal planes in the opposite case. This picture relating the structural parameters and anisotropy type can be generalized to the whole group of Tb-based compounds with the ZrNiAl type of structure.

Klicpera, M.; Javorsk, P.; Puente Orench, I.

2011-12-01

404

High granulocyte/lymphocyte ratio and paucity of NKT cells defines TB disease in a TB-endemic setting.  

PubMed

Most people infected with Mycobacterium tuberculosis, the causative agent of tuberculosis (TB) actually maintain a strong immune response and are able to control bacterial growth (deemed latently infected (LTBI)), while approximately 10% progress to disease resulting in almost 2 million deaths per year. Determining the immune 'footprint' at specific stages of infection and disease will allow for better diagnostics, treatments and ultimately development of new vaccine candidates. In this study we performed multi-factorial flow cytometry on fresh blood from 56 TB cases, 46 Tuberculin Skin Test (TST) positive (LTBI) and 39 TST negative household contacts. We found a highly significant increase in granulocytes and decrease in B cells and invariant (Valpha24+Vbeta11+) NKT cells in TB cases compared to TST+ contacts (p<0.0001, p=0.007 and p=0.01 respectively) which were restored to LTBI levels following 6 months of TB treatment. Using support vector analysis, we found a combination of granulocyte and lymphocyte and/or NKT cell proportions allowed almost 90% correct classification into M. tuberculosis infection or disease. This work has important public health benefits in regards to diagnosis and treatment of TB in sub-Saharan Africa and in furthering our understanding of the requirements for protective immunity to TB. PMID:19683473

Sutherland, Jayne S; Jeffries, David J; Donkor, Simon; Walther, Brigitte; Hill, Philip C; Adetifa, Ifedayo M O; Adegbola, Richard A; Ota, Martin O C

2009-11-01

405

Magnetic ordering and superconductivity in the R2Ir3Ge5 (R=Y, La, Ce Nd, Gd Tm, Lu) system  

NASA Astrophysics Data System (ADS)

We report crystal structure, electrical resistivity, magnetic susceptibility, isothermal magnetization, and heat-capacity studies on polycrystalline samples of the intermetallic series R2Ir3Ge5 (R=Y, La, Ce Nd, Gd Tm, Lu) from 1.5 to 300 K. We find that the compounds for R=Y, La-Dy, crystallize in the tetragonal Ibam (U2Co3Si5 type) structure whereas the compounds for R=Er Lu, crystallize in a different orthorhombic structure with a space group Pmmn. Samples of Ho2Ir3Ge5 were always found to be multiphase. The compounds for R=Y Dy which adopt the Ibam type structure show a metallic resistivity with a tendency of saturation at high temperatures whereas the compounds with R=Er, Tm, and Lu show an anomalous behavior in the resistivity with a semiconducting increase in ? as we go down in temperature from 300 K. Interestingly we had earlier found a positive temperature coefficient of resistivity for the Yb sample in the same temperature range. We will compare this behavior with similar observations in the compounds R3Ru4Ge13 and RBiPt. La2Ir3Ge5 and Y2Ir3Ge5 show bulk superconductivity below 1.8 K and 2.5 K, respectively. Our results confirm that Ce2Ir3Ge5 shows a Kondo-lattice behavior and undergoes antiferromagnetic ordering below 8.5 K. Most of the other compounds containing magnetic rare-earth elements undergo a single antiferromagnetic transition at low temperatures (T?12 K) while Gd2Ir3Ge5, Dy2Ir3Ge5, and Nd2Ir3Ge5 show multiple transitions. The TNs for most of the compounds roughly scale with the de Gennes factor, which suggests that the primary mechanism of interaction leading to the magnetic ordering of the magnetic moments may be the Ruderman-Kittel-Kasuya-Yosida interaction. The ordering temperature of 8.5 K for Ce2Ir3Ge5 is anomalously large compared to the TN for Gd2Ir3Ge5 which is about 12 K. There are signs of strong CEF influence on the measured properties for the series.

Singh, Yogesh; Ramakrishnan, S.

2004-05-01

406

Incipient Ferromagnetism in Tb2Ge2O7 : Application of Chemical Pressure to the Enigmatic Spin-Liquid Compound Tb2Ti2O7  

NASA Astrophysics Data System (ADS)

After nearly 20 years of study, the origin of the spin-liquid state in Tb2Ti2O7 remains a challenge for experimentalists and theorists alike. To improve our understanding of the exotic magnetism in Tb2Ti2O7 , we synthesize a chemical pressure analog: Tb2Ge2O7 . Substitution of titanium by germanium results in a lattice contraction and enhanced exchange interactions. We characterize the magnetic ground state of Tb2Ge2O7 with specific heat, ac and dc magnetic susceptibility, and polarized neutron scattering measurements. Akin to Tb2Ti2O7 , there is no long-range order in Tb2Ge2O7 down to 20 mK. The Weiss temperature of -19.2 (1 ) K , which is more negative than that of Tb2Ti2O7 , supports the picture of stronger antiferromagnetic exchange. Polarized neutron scattering of Tb2Ge2O7 reveals that liquidlike correlations dominate in this system at 3.5 K. However, below 1 K, the liquidlike correlations give way to intense short-range ferromagnetic correlations with a length scale similar to the Tb-Tb nearest neighbor distance. Despite stronger antiferromagnetic exchange, the ground state of Tb2Ge2O7 has ferromagnetic character, in stark contrast to the pressure-induced antiferromagnetic order observed in Tb2Ti2O7 .

Hallas, A. M.; Cheng, J. G.; Arevalo-Lopez, A. M.; Silverstein, H. J.; Su, Y.; Sarte, P. M.; Zhou, H. D.; Choi, E. S.; Attfield, J. P.; Luke, G. M.; Wiebe, C. R.

2014-12-01

407

Incipient ferromagnetism in tb_{2}ge_{2}o_{7}: application of chemical pressure to the enigmatic spin-liquid compound tb_{2}ti_{2}o_{7}.  

PubMed

After nearly 20 years of study, the origin of the spin-liquid state in Tb_{2}Ti_{2}O_{7} remains a challenge for experimentalists and theorists alike. To improve our understanding of the exotic magnetism in Tb_{2}Ti_{2}O_{7}, we synthesize a chemical pressure analog: Tb_{2}Ge_{2}O_{7}. Substitution of titanium by germanium results in a lattice contraction and enhanced exchange interactions. We characterize the magnetic ground state of Tb_{2}Ge_{2}O_{7} with specific heat, ac and dc magnetic susceptibility, and polarized neutron scattering measurements. Akin to Tb_{2}Ti_{2}O_{7}, there is no long-range order in Tb_{2}Ge_{2}O_{7} down to 20mK. The Weiss temperature of -19.2(1)??K, which is more negative than that of Tb_{2}Ti_{2}O_{7}, supports the picture of stronger antiferromagnetic exchange. Polarized neutron scattering of Tb_{2}Ge_{2}O_{7} reveals that liquidlike correlations dominate in this system at 3.5K. However, below 1K, the liquidlike correlations give way to intense short-range ferromagnetic correlations with a length scale similar to the Tb-Tb nearest neighbor distance. Despite stronger antiferromagnetic exchange, the ground state of Tb_{2}Ge_{2}O_{7} has ferromagnetic character, in stark contrast to the pressure-induced antiferromagnetic order observed in Tb_{2}Ti_{2}O_{7}. PMID:25615381

Hallas, A M; Cheng, J G; Arevalo-Lopez, A M; Silverstein, H J; Su, Y; Sarte, P M; Zhou, H D; Choi, E S; Attfield, J P; Luke, G M; Wiebe, C R

2014-12-31

408

Tracking and Treating Mobile Populations. The TB Net System. Migrant Clinicians Network Monograph Series. = El Sistema de Red para la TB.  

ERIC Educational Resources Information Center

A comprehensive tracking and referral network that helps provide continuity of care for mobile populations with active tuberculosis (TB) or TB infection is considered essential for effective treatment of TB. However, the interstate referral system that exists between state health departments has been highly inefficient for serving migrant

Migrant Clinicians Network, Inc., Austin, TX.

409

Electronic transitions in GdN band structure  

SciTech Connect

Using the near-infrared (NIR) absorbance spectroscopy, electronic transitions and spin polarization of the GdN epitaxial film have been investigated; and the GdN epitaxial film was grown by a reactive rf sputtering technique. The GdN film exhibited three broad bands in the NIR frequency regimes; and those bands are attributable primarily to the minority and majority spin transitions at the X-point and an indirect transition along the ?-X symmetric direction of GdN Brillouin zone. We experimentally observe a pronounced red-shift of the indirect band gap when cooling down below the Curie temperature which is ascribed to the orbital-dependent coulomb interactions of Gd-5dxy electrons, which tend to push-up the N-2p bands. On the other hand, we have evaluated the spin polarization of 0.17 (0.005), which indicates that the GdN epitaxial film has almost 100% spin-polarized carriers. Furthermore, the experimental result of GdN electronic transitions are consistent with the previous reports and are thus well-reproduced. The Arrott plots evidenced that the Curie temperature of GdN film is 36?K and the large spin moment is explained by the nitrogen vacancies and the intra-atomic exchange interaction.

Vidyasagar, R., E-mail: drsagar@sapphire.kobe-u.ac.jp; Kita, T. [Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Kobe 657-8501 (Japan); Sakurai, T. [Centre for Support to Research and Education Activities, Kobe University, 1-1 Rokkodai, Kobe 657-8501 (Japan); Ohta, H. [Molecular Photoscience Research Center and Graduate School of Science, Kobe University, 1-1 Rokkodai, Kobe 657-8501 (Japan)

2014-05-28

410

Electronic transitions in GdN band structure  

NASA Astrophysics Data System (ADS)

Using the near-infrared (NIR) absorbance spectroscopy, electronic transitions and spin polarization of the GdN epitaxial film have been investigated; and the GdN epitaxial film was grown by a reactive rf sputtering technique. The GdN film exhibited three broad bands in the NIR frequency regimes; and those bands are attributable primarily to the minority and majority spin transitions at the X-point and an indirect transition along the ?-X symmetric direction of GdN Brillouin zone. We experimentally observe a pronounced red-shift of the indirect band gap when cooling down below the Curie temperature which is ascribed to the orbital-dependent coulomb interactions of Gd-5dxy electrons, which tend to push-up the N-2p bands. On the other hand, we have evaluated the spin polarization of 0.17 (0.005), which indicates that the GdN epitaxial film has almost 100% spin-polarized carriers. Furthermore, the experimental result of GdN electronic transitions are consistent with the previous reports and are thus well-reproduced. The Arrott plots evidenced that the Curie temperature of GdN film is 36 K and the large spin moment is explained by the nitrogen vacancies and the intra-atomic exchange interaction.

Vidyasagar, R.; Kita, T.; Sakurai, T.; Ohta, H.

2014-05-01

411

The hydrogenation of Dy{sub 5}Pd{sub 2} followed by in situ methods  

SciTech Connect

The hydrogenation behavior of the intermetallic compound Dy{sub 5}Pd{sub 2} was investigated by means of ex situ X-ray powder diffraction, in situ neutron powder diffraction and in situ differential scanning calorimetry. The structural model of Dy{sub 5}Pd{sub 2} with a palladium atom at the 32(e) position x, x, x (x Almost-Equal-To 0.22, 7/8 occupation) and a dysprosium atom at almost the same location (x Almost-Equal-To 0.18, 1/8 occupation) is confirmed. Upon heating the latter approaches x(Pd) and at T=399 K both positional parameters are indistinguishable. Dy{sub 5}Pd{sub 2} does not incorporate hydrogen (deuterium) into its crystal structure, however, starting at T=495 K reacts with hydrogen to non stoichiometric dysprosium dideuteride, DyD{sub 2+x}, following a parabolic rate law. In situ differential scanning calorimetry at various hydrogen pressures up to 2.5 MPa shows strongly exothermic signals, whose temperature onset depend on the gas pressure, corresponding to the formation of a mainly ionic hydride (DyH{sub 2+x}). - Graphical abstract: The hydrogenation of Dy5Pd2 is being followed by in situ neutron diffraction. Highlights: Black-Right-Pointing-Pointer Dy5Pd2 does not form a ternary hydride upon hydrogenation. Black-Right-Pointing-Pointer Dy5Pd2 decomposes to binary hydrides of dysprosium and palladium. Black-Right-Pointing-Pointer At T{>=}399 K Dy3 and Pd in the crystal structure of Dy5Pd2 share the same position. Black-Right-Pointing-Pointer The formation of DyD2+x at T=495 K and p(D2)=2.5 MPa follows a parabolic rate law.

Kohlmann, H., E-mail: h.kohlmann@mx.uni-saarland.de [Inorganic Solid State Chemistry, Saarland University, Am Markt, Zeile 3, 66125 Saarbruecken (Germany); Talik, E. [Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Hansen, T.C. [Institut Laue-Langevin, 6, Rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9 (France)

2012-03-15

412

Radioactivity measurements of 153Gd pellet sources by calorimetric methods  

NASA Astrophysics Data System (ADS)

The thermal power generation per 37 MBq (1 mCi) of 153Gd is 0.839 ?W. The activity of a sealed 153Gd source can be determined by absorbing all radiations within a calorimeter to be converted into the thermal power. Sources are sintered pellets (3 mm diameter, 2 mm thickness) of Gd2O3Al2O3 which are encapsulated in titanium capsules of 7 mm diameter and 10 mm length. A cylindrical radiation absorber made of solid copper having a space in the center for the 153Gd source is used and the temperature rise of the absorber is measured. Uncertainties are added up to 2.9% for a 3? confidence interval in the final result for the measurement of the activity of an approximately 1.5 GBq (40 mCi) pellet source of 153Gd in a fully nondestructive way.

Genka, Tsuguo; Imahashi, Tsuyoshi

1992-02-01

413

Teaching Applied Measuring Methods Using GD&T  

NSDL National Science Digital Library

Products are generally specified using the American Society of Mechanical Engineers 1994 standard Y 14.5M on Geometric Dimensioning and Tolerancing, commonly known as GD&T. Engineering technology graduates who work in design, or manufacturing, or quality, need to have expertise in the principles of measurement science and practical interpretation of GD&T based product specifications. A new course on metrology has been recently introduced in an engineering technology curriculum where students apply the GD&T theory in to practice by inspecting parts using these GD&T tolerance specifications. The paper describes the highlights of metrology course and some of the experiments that students do to measure using GD&T methods. The paper also discusses the lessons learned from the students performance in class and laboratory, and gives their feedback on the extent of achieving the proposed course outcomes.

Narang, Ramesh

414

Temperature dependence of57Fe hyperfine field in Gd: YIG  

NASA Astrophysics Data System (ADS)

The NMR spectra of57Fe in Gd: YTG polyeryslallaline samples were measured between liquid-helium and room temperatures. In spectra of57Fe on tetrahedral sites, beside the main line, weaker and broader peak at higher frequencies appears. It can be decomposed in to the three satellites corresponding to Fe3+ ion with one Gd3+ ion in the nearest (two satellites) and next nearest dodecahedral site. The temperature dependence of the stellite resonance frequency indicates, that the part of the transferred hyperfine field on57Fe with the Gd3+ in the nearest c-site depends on the magnetic moment of Gd3+ ion. The resonance frequency of the satellite corresponding to the57Fe with Gd3+ in the next nearest c-site follows the temperature dependence of the dipolar field, the change of the transferred field is small.

Englich, J.; Novk, P.; Kuriplach, J.; Ltgemeier, H.

1990-08-01

415

Gyromagnetic ratios in sup 164 Dy and sup 168 Er  

SciTech Connect

Gyromagnetic ratios of levels up to 10{sup +} in the ground-state bands and of the 2{sup +} states in the {gamma} bands of {sup 164}Dy and {sup 168}Er were measured by the perturbed angular correlation technique utilizing the transient hyperfine field acting at the nuclei of these ions as they swiftly traversed thin polarized Fe foils. The experimental {ital g} factors, together with the results of ea