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1

Electrochemical deoxidation of RE–O (RE=Gd, Tb, Dy, Er) solid solutions  

Microsoft Academic Search

The removal of oxygen from rare-earth metals (RE, RE=Gd, Tb, Dy, Er) by an electrochemical deoxidation method was investigated. A titanium basket containing the rare-earth metal sample, submerged in molten CaCl2 electrolyte, formed the cathode of an electrolysis cell. A high-purity graphite anode was used. The calcium metal produced at the cathode effectively deoxidized the rare-earth metal. Carbon monoxide and

K. Hirota; T. H. Okabe; F. Saito; Y. Waseda; K. T. Jacob

1999-01-01

2

Magnetic properties of some RPd 2 Si 2 compounds (R=Gd, Tb, Dy, Ho and Er)  

Microsoft Academic Search

The magnetic susceptibility of the ternary compounds, RPd2Si2 (where R=Gd, Tb, Dy, Ho and Er) has been measured. GdPd2Si2 order antiferromagnetically at 13 and 20 K respectively; the rest of the compounds do not show clear ordering down to 4.2 K. Palladium carries no moment in these compounds. The De Gennes formula is not obeyed indicating that the exchange interaction

J. K. Yakinthos; Halen Gamari-Seale

1982-01-01

3

Magnetic properties of some RPd2Si2 compounds (R=Gd, Tb, Dy, Ho and Er)  

NASA Astrophysics Data System (ADS)

The magnetic susceptibility of the ternary compounds, RPd2Si2 (where R=Gd, Tb, Dy, Ho and Er) has been measured. GdPd2Si2 order antiferromagnetically at 13 and 20 K respectively; the rest of the compounds do not show clear ordering down to 4.2 K. Palladium carries no moment in these compounds. The De Gennes formula is not obeyed indicating that the exchange interaction between the 4 f moments via conduction electrons is not isotropic

Yakinthos, J. K.; Gamari-Seale, Halen

1982-09-01

4

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

Microsoft Academic Search

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

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

1992-01-01

5

Magnetostriction in (Tb sub x Dy sub 1 minus x ) sub 80 Gd sub 20 single crystals  

SciTech Connect

Gd has been added to binary alloys of Tb and Dy in order to raise the magnetic transition temperature and zero-anisotropy temperature of the alloys. Magnetostriction and differential-scanning-calorimetry measurements were made on four samples of the alloy system (Tb{sub {ital x}}Dy{sub 1{minus}{ital x}}){sub 80}Gd{sub 20} over temperatures from 50 to 300 K in applied fields of 6--20 kOe. The two lowest-order basal-plane magnetostriction constants were derived from the data, as was the basal-plane anisotropy constant. The addition of 20% Gd was found to increase the magnetic transition temperatures, but to decrease or eliminate the zero-anisotropy temperature.

Spano, M.L.; Clark, A.E.; Wun-Fogle, M.; Lynn, H.D. (Naval Surface Warfare Center, White Oak Laboratory, Silver Spring, Maryland 20903-5000 (USA))

1990-05-01

6

Nuclear quadrupole interaction studies of C15 RMn2 hydrides ( R=Y ,Gd,Tb,Dy)  

NASA Astrophysics Data System (ADS)

The nuclear electric quadrupole interaction (QI) of the probe nucleus I111n/C111d in the paramagnetic phase of the C15 rare earth (R) manganese hydrides (deuterides) RMn2H(D)x , with R=Y , Gd, Tb, and Dy, has been investigated by perturbed angular-correlation spectroscopy. The QI between the C111d quadrupole moment and the electric-field gradient (EFG) at the probe nucleus on the Mn site has been measured as a function of temperature in TbMn2H(D)x in the concentration range 0?x?4.3 and in RMn2H(D)x , R=Y ,Gd,Dy at the highest H content of xtilde 4.3 . The relative temperature dependence of the EFG in the parent compounds RMn2 is twice as strong as in isostructural RAl2 which can be related to differences in the Debye temperatures resulting from different radius ratios rR/rMn and rR/rAl [Joseph-Gschneidner postulate, Scr. Metall.2, 631 (1968)]. Hydrogenation of RMn2 increases the magnitude of the EFG by a factor of 2 between x=0 and x=4.3 but leaves the relative temperature dependence almost unchanged. Only at concentrations x>3.6 the temperature coefficient of the QI is significantly larger than in uncharged RMn2 . These results are compared with the much stronger concentration dependence and the anomalous temperature dependence of the QI of C111d in the C15 hydrides HfV2Hx . Evidence for an exceptionally high H mobility in TbMn2Hx is presented. The measurements provide information on structural changes and magnetic ordering temperatures at different H concentrations.

Forker, M.; Bedi, S. C.; Euler, H.

2008-09-01

7

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

8

ac susceptibility study on R2Fe14B single crystals (R=Y, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm)  

Microsoft Academic Search

The temperature dependence of the ac susceptibility chi=chi'+ichi'' has been measured on R2Fe14B single crystals with R=Y, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm as a function of temperature in the temperature interval from 4.2 to 300 K, as a function of the strength of the applied ac field (up to 800 A\\/m), as a function of

X. C. Kou; R. Grössinger; G. Hilscher; H. R. Kirchmayr; F. R. de Boer

1996-01-01

9

Magnetic properties of R ions in RCo5 compounds (R=Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er)  

NASA Astrophysics Data System (ADS)

The values of the R-Co exchange field Hex and the crystalline-electric-field parameters Amn at the rare-earth (R) site in RCo5 (R=Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er) and Y1-xNdxCo5 (x=0.5, 0.6, 0.8, and 1.0) compounds are evaluated by a comparison of calculations with a series of experiments. The experiments provide the following data: temperature dependence of spontaneous magnetization of the compounds and magnetic moment of the rare-earth ion, magnetization curves along the crystallographic axes, and temperature dependence of the easy direction of magnetization. The anisotropies of the R-Co exchange interaction and the magnetic moment of the Co sublattice are taken into account in the calculation. The R-Co exchange field Hex decreases monotonically across the rare-earth series from Pr to Er. For PrCo5, the value of A02 is much smaller than those of the other compounds, which suggests valence fluctuations for the Pr ion. For Y1-xNdxCo5 and SmCo5, the absolute value of A02 decreases with increasing temperature.

Tie-Song, Zhao; Han-Min, Jin; Guang-Hua, Guo; Xiu-Feng, Han; Hong, Chen

1991-04-01

10

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

11

Theoretical investigations on magnetic entropy change in amorphous and crystalline systems: Applications to RAg (R=Tb, Dy, Ho) and GdCuAl  

NASA Astrophysics Data System (ADS)

We report theoretical investigations on the magnetic entropy changes in amorphous systems through two different assumptions. In the first assumption, the HPZ-anisotropic model is considered to deal with the random direction of magnetic moments, where the amorphous RAg (R=Tb, Dy and Ho) were used as prototypes systems. In the second assumption, the amorphisation is parameterized through the exchange interaction distribution and GdCuAl, in amorphous and crystalline structures, were considered as prototypes systems. Comparisons between the magnetic entropy changes under amorphisation and under the usual magnetic field variation were performed. The model reveals the dependence of refrigerant capacity on the amorphisation parameter, and an optimum amorphisation parameter was calculated.

von Ranke, P. J.; Nóbrega, E. P.; Caldas, A.; Alho, B. P.; Ribeiro, P. O.; Alvarenga, T. S. T.; Lopes, P. H. O.; de Sousa, V. S. R.; Carvalho, A. Magnus G.; de Oliveira, N. A.

2014-11-01

12

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

Microsoft Academic Search

Spherical SiO particles have been coated with rare earth oxide layers by a Pechini sol-gel process, leading to the formation of core-shell structured SiO-REO (RE=rare earth elements) and SiO-GdO: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

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

2009-01-01

13

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

14

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 Å, b?3.75 Å, c?9.65 Å 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

15

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

SciTech Connect

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

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

2010-09-15

16

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

17

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

18

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

SciTech Connect

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

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

2011-04-15

19

Ac susceptibility study on {ital R}{sub 2}Fe{sub 14}B single crystals ({ital R}=Y, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm)  

SciTech Connect

The temperature dependence of the ac susceptibility {chi}={chi}{sup {prime}}+{ital i}{chi}{sup {double_prime}} has been measured on {ital R}{sub 2}Fe{sub 14}B single crystals with {ital R}=Y, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm as a function of temperature in the temperature interval from 4.2 to 300 K, as a function of the strength of the applied ac field (up to 800 A/m), as a function of frequency (ranging from 5 to 1000 Hz), as well as the dependence on the crystallographic orientation. A reversible rotation of magnetic moments, excited by applying the field perpendicular to the easy magnetization direction, is found to be the principal contribution to the susceptibility ({chi}{sup {prime}}). The energy loss is fairly small in this case ({chi}{sup {double_prime}}{approx_equal}0). When the external field is applied parallel to the easy magnetization direction, domain-wall movement is the main contribution to the susceptibility ({chi}{sup {prime}}) and to the energy loss ({chi}{sup {double_prime}}). For Nd{sub 2}Fe{sub 14}B, a peak in {chi}{sup {double_prime}}({ital T}) is detected at 135 K, the spin-reorientation temperature, in a 5 Hz field of 40 A/m applied along the [001] direction. This peak disappears upon increasing the frequency or upon changing the crystallographic orientation of the crystal. In addition, an anomaly in the temperature dependence of the susceptibility is detected around 220 K for {ital R}{sub 2}Fe{sub 14}B single crystals with {ital R}=Pr, Nd, Sm, Tb, and Dy. The presence of this anomaly depends on the crystallographic orientation. It can only be detected when the external field is applied parallel to the [001] direction. For all frequencies used, the temperature dependence of {chi}{sup {prime}} is completely different from that of {chi}{sup {double_prime}}. The {chi}{sup {prime}} values are nearly independent of the frequency in our measuring range from 5 to 1000 Hz. (Abstract Truncated)

Kou, X.C.; Groessinger, R.; Hilscher, G.; Kirchmayr, H.R. [Institute for Experimental Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A-1040 Vienna (Austria)] [Institute for Experimental Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A-1040 Vienna (Austria); de Boer, F.R. [Van der Waals-Zeeman Institute, University of Amsterdam, Valckenierstraat 65, NL-1018 XE Amsterdam (The Netherlands)] [Van der Waals-Zeeman Institute, University of Amsterdam, Valckenierstraat 65, NL-1018 XE Amsterdam (The Netherlands)

1996-09-01

20

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

21

(Ln = Eu, Tb, and Dy) Powders  

NASA Astrophysics Data System (ADS)

BaWO4:Ln3+ powders were synthesized by a solid-state reaction method. The BaWO4:Ln3+ samples were characterized by x-ray powder diffraction (XRD) analysis, scanning electron microscopy (SEM), and luminescence spectroscopy. The XRD patterns reveal that the BaWO4:Ln3+ samples present pure tetragonal scheelite structure. The SEM observations demonstrate that the BaWO4:Ln3+ powders are irregular particles with size in the range of micrometers. The excitation spectra of the BaWO4:Ln3+ samples show the broad absorption band originating from charge transfer between oxygen ligands and the central tungstate ions inside WO{4/2-} groups in the metal tungstate. The emission spectra of the BaWO4:Ln3+ samples display the bands associated to the anion molecular complex (WO{4/2-}) and the f- f transitions of Ln3+. According to the emission spectra and the chromaticity coordinates (Commission internationale de l'éclairage, CIE), one can see that the BaWO4:Eu3+, BaWO4:Tb3+, and BaWO4:Dy3+ samples show emission in the red, green, and yellow region, respectively. The results show that the luminescence color can be altered by changing the Ln3+ doping in BaWO4 material.

Sun, Xiaoyu; Sun, Xiaodan; Li, Xingang; He, Jian; Wang, Binsheng

2014-09-01

22

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

23

Synthesis and characterization of monodisperse spherical SiO2@RE2O3 (RE=rare earth elements) and SiO2@Gd2O3:Ln3+ (Ln=Eu, Tb, Dy, Sm, Er, Ho) particles with core-shell structure  

Microsoft Academic Search

Spherical SiO2 particles have been coated with rare earth oxide layers by a Pechini sol-gel process, leading to the formation of core-shell structured SiO2@RE2O3 (RE=rare earth elements) and SiO2@Gd2O3:Ln3+ (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

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

2009-01-01

24

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

Microsoft Academic Search

Spherical SiO2 particles have been coated with rare earth oxide layers by a Pechini sol–gel process, leading to the formation of core-shell structured SiO2@RE2O3 (RE=rare earth elements) and SiO2@Gd2O3:Ln3+ (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

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

2009-01-01

25

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

PubMed

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

Hiroto, T; Tokiwa, K; Tamura, R

2014-05-28

26

Antiferromagnetic Coupling of Pr0.9RE0.1Ni (RE = Tb, Dy, Ho) Single Crystals  

NASA Astrophysics Data System (ADS)

Magnetization and specific heat measurements were carried out on Pr0.9RE0.1Ni (RE = Tb, Dy, and Ho) single crystals. Spin rearrangements were observed along the c-axis of single crystals with relatively small critical fields, Bc = 6.8, 4.0, and 2.6 T for RE = Tb, Dy and Ho, respectively. The magnetic phase transition temperatures, TM, were extracted from the specific heat data: TM = 22.7, 19.6, and 18.3 K with RE = Tb, Dy, and Ho, respectively. The observed Bc values were used to estimate the heterogeneous (Pr-RE) exchange strength, and then calculate expected TM values, which were found to be close to the experimental ones. The present results of Bc and TM, together with the previous ones of Pr0.9Gd0.1Ni, were found to be consistent with the de Gennes rule.

Nishimura, Katsuhiko; Hutchison, Wayne D.; Namiki, Takahiro

2013-05-01

27

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

28

Structural complexity meets transport and magnetic anisotropy in single crystalline Ln30Ru4Sn31 (Ln = Gd, Dy).  

PubMed

We present the structure of Ln(30)Ru(4+x)Sn(31-y) (Ln = Gd, Dy) and the anisotropic resistivity, magnetization, thermopower, and thermal conductivity of single crystal Ln(30)Ru(4+x)Sn(31-y) (Ln = Gd, Tb). Gd(30)Ru(4.92)Sn(30.54) crystallizes in a new structure-type with space group Pnnm and dimensions of a = 11.784(1) Å, b = 24.717(1) Å, and c = 11.651(2) Å, and V = 3394(1) Å(3). Magnetic anisotropy and highly anisotropic electrical transport behavior were observed in the single crystals of Gd(30)Ru(4.92)Sn(30.54) and Tb(30)Ru(6)Sn(29.5). Additionally, the lattice thermal conductivity of Tb(30)Ru(6)Sn(29.5) is quite low, and a comparison is made to other Sn-containing compounds. PMID:23350732

Schmitt, Devin C; Haldolaarachchige, Neel; Prestigiacomo, Joseph; Karki, Amar; Young, David P; Stadler, Shane; Jin, Rongying; Chan, Julia Y

2013-02-20

29

Crystallization behaviour and magnetic properties of highly magnetostrictive Fe-Tb-Dy thin films  

NASA Astrophysics Data System (ADS)

Thin films of the Fe-Tb-Dy alloy with compositions near to the Terfenol-D alloy (Fe 67Tb 9Dy 24) have been produced by ion-beam sputtering on sapphire substrates at room temperature. Mosaic and sintered targets have been used to vary the chemical composition of Fe, Tb and Dy. Additionally, 2 at% of the additive Zr has been used for some films. Polycrystalline films consisting mainly of the Fe 2RE (RE=Tb, Dy) Laves phase could be obtained by subsequent heat treatment for all compositions investigated here. Measurements of the magnetostriction, the magnetic polarization and the Curie temperature combined with wide-angle X-ray diffraction (XRD) and wavelength dispersive X-ray analysis (WDX) allowed an interpretation of the crystallization behaviour. It has been found that Fe excess increases and rare earth excess decreases the crystallization temperature, whereas the addition of Zr leaves the crystallization temperature unaffected.

Farber, P.; Kronmüller, H.

2000-06-01

30

Comparison of the dynamic magnetomechanical properties of Tb0.27Dy0.73Fe2 and Tb0.30Dy0.70Fe2  

NASA Astrophysics Data System (ADS)

Comparison is made between the magnetomechanical properties of Tb0.27Dy0.73Fe2 (27 Tb) and Tb0.30Dy0.70Fe2 (30 Tb), two commercially available composition of the giant magnetostrictive alloy Terfenol-D. The quasi-static magnetostriction (as a function of bias field) and the dynamic strain coefficient (as a function of bias field and frequency) are shown for the two composition at room temperature, using stress bias values of 0 and 9 MPa. The energy loss per cycle as a function of frequency is also given. The data for the static magnetostriction versus bias field shows 30 Tb to exhibit a significantly greater increase in initial slope and saturation strain when stress bias is applied compared to that seen for 27 Tb, which possesses superior magnetostriction at zero stress bias. A similar trend is observed in the data for the dynamic strain coefficient with 30 Tb again performing better under stress bias. The widening of the static strain hysteresis loop observed for stressed 30 Tb is seen to manifest itself in the low frequency energy loss per cycle; however 27 Tb is observed to possess the higher eddy current loss at 1 kHz. Data for the ratio d/chi, a quantity which is dependent only on magnetization processes and material constants, are shown which suggests that the application of a stress bias affects the magnetization processes, but differently for the two compositions.

Kendall, D.; Piercy, A. R.

1994-11-01

31

Magnetic properties of RMn2Ge2 compounds (R=La, Ce, Pr, Nd, Cd, Tb, Dy, Ho, Er, and Th)  

Microsoft Academic Search

Magnetic properties RMn2Ge2 compounds where R is La, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er, and Th have been investigated from 4.2 to 500 K. LaMn2Ge2, CeMn2Ge2, PrMn2Ge2, and NdMn2Ge2 are ferromagnetic with Curie temperatures of 306, 316, 334, and 334 K, respectively. The heavy rare-earth compounds do not order ferromagnetically until low temperatures. GdMn2Ge2 shows a sharp magnetic

K. S. V. L. Narasimhan; R. L. Bergner; W. E. Wallace

1975-01-01

32

Spin structure and magnetic frustration in multiferroic RMn2O5 (R=Tb,Ho,Dy)  

Microsoft Academic Search

We have studied the crystal and magnetic structures of the magnetoelectric\\u000amaterials RMn2O5 (R = Tb, Ho, Dy) using neutron diffraction as a function of\\u000atemperature. All three materials display incommensurate antiferromagnetic\\u000aordering below 40 K, becoming commensurate on further cooling. For R = Tb, Ho,\\u000aa commensurate-incommensurate transition takes place at low temperatures. The\\u000acommensurate magnetic structures have been

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

2005-01-01

33

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

SciTech Connect

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

Wang, Fang; Tang, Chunying; Chen, Ruihong; Zhang, Yong; Jia, Dingxian, E-mail: jiadingxian@suda.edu.cn

2013-10-15

34

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

35

The magnetostriction and its ratio to hysteresis for Tb-Dy-Ho-Fe alloys  

NASA Astrophysics Data System (ADS)

The x(Tb0.15Ho0.85Fe2) + (1 - x)(Tb0.3Dy0.7Fe2) alloys were prepared in an arc furnace under high purity argon. The as-cast samples wrapped in Mo foil were sealed in a silica tube filled with high purity argon. The static measurement of magnetostriction (?//, ??) was made by standard strain gauge, and the magnetization M was measured by a vibrating sample magnetometer. It is found that the magnetostriction ?// of x(Tb0.15Ho0.85Fe2) + (1 - x)(Tb0.3Dy0.7Fe2) alloys decreases with increasing x and it does from 880 × 10-6 for x = 0 to 210 × 10-6 for x = 0.9 at the magnetic field of 640 kA/m. The ratio (?///Wh) of magnetostriction to hysteresis exhibits a peak when x = 0.1, and it means that the Tb0.285Dy0.63Ho0.085Fe2 (x = 0.1) alloy possesses both large magnetostriction and small magnetostrictive hysteresis.

Wang, Bowen; Lv, Yan; Li, Guolu; Huang, Wenmei; Sun, Ying; Cui, Baozhi

2014-05-01

36

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

37

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

Microsoft Academic Search

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

Jong Hyeon Lee; R. H. Byrne

1993-01-01

38

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

SciTech Connect

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

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

2012-05-17

39

Physical metallurgy of metastable Bcc lanthanide-magnesium alloys for R = La, Gd, and Dy  

SciTech Connect

Bcc La-Mg, Gd-Mg, and Dy-Mg alloys have been prepared by an ice water/acetone quench from liquid melts. Single-phase alloys could be retained in a window around the eutectoid composition: 13 to 22 at. pct Mg, 23.6 to 29 at. pct Mg, and 27 to 29 at. pct Mg for La, Gd, and Dy alloys, respectively. At the center of the windows, x-ray diffraction peaks are extremely sharp as in equilibrium bcc structures; however, as alloy composition is moved away from the eutectoid, line broadening is observed. Reversion of the bcc phase to the equilibrium microstructure for R-Mg alloys (R = La, Gd, or Dy) has been characterized by differential thermal analysis (DTA) or differential scanning calorimetry (DSC) and isothermal annealing. La-Mg alloys revert directly to {alpha}La (dhcp) + LaMg at about 350{degrees}C when heated at 10{degrees}C/min. In contrast, the Gd and Dy alloys revert by a two-step process: first, a transition to an intermediate distorted hcp phase between 300{degrees}C and 400{degrees}C, and, second, the relaxation of this phase to {alpha}R (hcp) + RMg at about 490{degrees}C when heated at 10{degrees}C/min. Isothermal annealing and high temperature x-ray diffraction confirm the nature of these reactions.

Herchenroeder, J.W. (Delco Remy, Div. of General Motors Corp., IN (US)); Manfrinetti, P. (via acquistapace 4/5, 15067 Novi Ligure, AL (IT)); Gschneidner, K.A. Jr. (Ames Lab. and Dept. of Materials Science and Engineering, Iowa State Univ., Ames, IA (US))

1989-09-01

40

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

41

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 200°C. 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

42

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

43

Structure and magnetic properties of melt-spun Tb 0.27Dy 0.73Fe x ribbons  

NASA Astrophysics Data System (ADS)

The structure and magnetic properties of the melt-spun ribbons of Tb 0.27Dy 0.73Fe x alloy are investigated as a function of various wheel speeds during melt-quenching using a single-roll technique. It is found that Tb 0.27Dy 0.73Fe x alloy is difficult to be fabricated as amorphous state by using the melt-quenching method. X-ray diffractions show that all these ribbons for x=1.7-2.0 are the MgCu 2-type phase at the wheel speed of 45 m s -1. For Tb 0.27Dy 0.73Fe x alloy, the high wheel speed is beneficial to eliminate the RFe 3 phase and form the perfect MgCu 2-type phase. Compared with the bulk of Tb 0.27Dy 0.73Fe 1.95, these ribbons exhibit higher intrinsic coercivity value and their saturation magnetizations increase as well. The magnetostriction of Tb 0.27Dy 0.73Fe 1.95 composite with 4% epoxy resin is 640×10 -6 at 900 kA m -1.

Liu, H. Y.; Li, Y. X.; Zhang, M.; Meng, X. X.; Qu, J. P.; Chen, J. L.; Wu, G. H.

44

The Giant Magnetostriction of [Fe/Tb/Fe/Dy]n Multilayer Films Under Different Annealing Temperature  

NASA Astrophysics Data System (ADS)

The effect of annealing temperature on the magnetic and giant magnetostriction (GMS) of [Fe/Tb/Fe/Dy]n multilayer films were investigated. X-ray diffraction showed that the multilayer films' microstructures were still in amorphous at annealing temperature 300°C. The multilayer films began to crystalline at annealing temperature 400°C. The saturation magnetization of multilayer films increased by the increasing annealed temperature. The coercivity first decreased at annealing temperature 300°C and then increased when the annealing temperature was higher than 400°C. The multilayer films had good low-field GMS, and the magnetostriction of the multilayer films increased by the increasing annealing temperature.

Li, X. D.; Zhao, Z. J.; Feng, T.; Pan, L. K.; Huang, S. M.; Chen, Y. W.; Sun, Z.

45

Multicolor tunable luminescence and paramagnetic properties of NaGdF?:Tb³?/Sm³? 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

46

Anion disorder in lanthanoid zirconates Gd(2-x)Tb(x)Zr2O7.  

PubMed

The pyrochlore-defect fluorite order-disorder transition has been studied for a series of oxides of the type Gd(2-x)Tb(x)Zr2O7 by a combination of diffraction and spectroscopy techniques. Synchrotron X-ray diffraction data suggest an abrupt transition from the coexistence of pyrochlore and defect fluorite phases to a single defect fluorite phase with increasing Tb content. However neutron diffraction data, obtained at ? ? 0.497 Å for all Gd-containing samples to minimize absorption, not only provide evidence for independent ordering of the anion and cation sublattices but also suggest that the disorder transition across the pyrochlore-defect fluorite boundary of Ln2Zr2O7 is rather gradual. Such disorder was also evident in X-ray absorption measurements at the Zr L3-edge, which showed a gradual increase in the effective coordination number of the Zr from near 6-coordinate in the pyrochlore rich samples to near 7-coordinate in the Tb rich defect fluorites. These results indicate the presence of ordered domains throughout the defect fluorite region, and demonstrate the gradual nature of the order-disorder transition across the Gd(2-x)Tb(x)Zr2O7 series. PMID:23844979

Reynolds, Emily; Blanchard, Peter E R; Kennedy, Brendan J; Ling, Chris D; Liu, Samuel; Avdeev, Max; Zhang, Zhaoming; Cuello, Gabriel J; Tadich, Anton; Jang, Ling-Yun

2013-08-01

47

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

NASA Astrophysics Data System (ADS)

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: REAg3In3 (YbAg2In4-type, space group Im-3), REAg2In (MnCu2Al-type, space group Fm-3m) and RE2AgIn3 (CaIn2-type, space group P63/mmc) RE=Tb, Dy. Homogeneity ranges of the ternary phases with CaIn2 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 REIn3 (AuCu3-type, space group Pm-3 m) binary compounds up to 5 at% of Ag has been found.

Demchyna, M.; Belan, B.; Manyako, M.; Pietraszko, A.; Kalychak, Ya.

2012-08-01

48

Synthesis and structure of new pyrochlore-type oxides Ln2ScNbO7 (Ln = Pr, Nd, Eu, Gd, Dy)  

E-print Network

and structure of new pyrochlore-type oxides Ln2ScNbO7 (Ln = Pr, Nd, Eu, Gd, Dy) S. Zouaria,b , R. Ballou b , A = Pr, Eu, Gd and Dy are obtained. All crystallize in the cubic pyrochlore structure type, space group F; pyrochlores; crystal structure; magnetic materials. Corresponding author: P. STROBEL Institut Néel, CNRS Case

Boyer, Edmond

49

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

PubMed

Herein, we report highly bright multicolor-emitting ?-Na(Y,Gd)F?:Ce,Tb,Eu/?-NaYF? nanoparticles (NPs) with precise color tunability. First, highly bright sub-20 nm ?-Na(Y,Gd)F?:Ce,Tb,Eu NPs were synthesized via a heating-up method. By controlling the ratio of Eu(3+) to Tb(3+), we generated green, yellow-green, greenish yellow, yellow, orange, reddish orange, and red emissions from the NP solutions via energy transfer of Ce(3+)? Gd(3+)? Tb(3+) (green) and Ce(3+)? Gd(3+)? Tb(3+)? Eu(3+) (red) ions under ultraviolet light illumination (254 nm). Because of Ce(3+) and Gd(3+) sensitization, Tb(3+) ions exhibited strong green emission. The decay time of Tb(3+) emission decreased from 4.0 to 1.4 ms as the Eu(3+) concentration was increased, suggesting that energy was transferred from Tb(3+) to Eu(3+). As a result, Eu(3+) emission peaks were generated and the emission color was transformed from green to red. Monodisperse sub-6 nm ?-Na(Y,Gd)F?:Ce,Tb,Eu NPs were synthesized through a simple reduction of the reaction temperature. Although fine color tunability was retained, their brightness was considerably decreased owing to an increase in the surface-to-volume ratio. The formation of a ?-NaYF? shell on top of the sub-6 nm NP core to produce ?-Na(Y,Gd)F?:Ce,Tb,Eu/?-NaYF? significantly increased the emission intensity, while maintaining the sub-10 nm sizes (8.7-9.5 nm). Quantum yields of the ultrasmall NPs increased from 1.1-6.9% for the core NPs to 6.7-44.4% for the core/shell NPs. Moreover, highly transparent core/shell NP-polydimethylsiloxane (PDMS) composites featuring a variety of colors, excellent color tunability, and high brightness were also prepared. PMID:23945563

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

2013-10-01

50

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

PubMed

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 C4h(6). 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. PMID:23735207

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

2013-09-01

51

Thermal and Mechanical Properties of ACoO3 (R = Sm, Tb, Dy, Ho, and Er)  

NASA Astrophysics Data System (ADS)

The thermal and mechanical properties of orthocobaltates, ACoO3 (A = Sm, Tb, Dy, Ho, and Er), have been investigated using the modified rigid ion model (MRIM) by incorporating the effect of lattice distortions. We have computed the variations of specific heat and thermal expansion coefficient for these orthocobaltates in wide temperature range of 1 K (-272 °C) ? T ? 1000 K (727 °C). The calculated results of specific heat, thermal expansion, bulk modulus, and other thermal and mechanical properties accord very well with the available experimental data, implying that MRIM represents properly the nature of the perovskite-type rare earth cobaltates. In addition, we have also reported the results on molecular force constant ( f), Reststrahlen frequency ( ?), cohesive energy ( ?), Debye temperature ( ? D), and Gruneisen parameter ( ?).

Gaur, N. K.; Thakur, Rasna

2013-12-01

52

Magnetization and specific heat studies of RNi 4Ga (R dbnd6 Sm, Gd and Tb)  

NASA Astrophysics Data System (ADS)

In order to elucidate the anomalous magnetic properties in the ferromagnetically ordered state of SmNi 4Ga GdNi 4Ga and TbNi 4Ga, we have carried out a detailed study with magnetization and specific heat (SH) measurements. GdNi 4Ga shows the possibility of a filled 3d band and a helical spin arrangement below the ordering temperature. TbNi 4Ga shows a dominant crystal field effect resulting in a deviation of TC from the de-Gennes scaling and possible Schottky anomalies in the SH. SmNi 4Ga shows a large coercivity at low temperatures. A rough estimate of the domain wall thickness in SmNi 4Ga gives a value of 8 Å.

Joshi, Devang A.; Tomy, C. V.; Nagarajan, R.; Malik, S. K.

2007-06-01

53

Lorentz microscopy on dynamically written domains in GdTbFe  

SciTech Connect

In this letter a new method for the observation of thermomagnetically written domains using Lorentz electron microscopy is discussed. Domains are written in a GdTbFe layer deposited on a specially prepared silicon wafer disk, provided with Si/sub 3/N/sub 4/ windows. This allows direct observation by Lorentz microscopy of the magnetization patterns dynamically written under recording conditions. It is shown that by locally heating the GdTbFe layer with a continuous laser beam, combined with high-frequency switching of the magnetic field, very high storage densities can be achieved. Domains with a length of 0.25 ..mu..m in the direction of disk rotation could be written.

Greidanus, F.J.A.M.; Jacobs, B.A.J.; den Broeder, F.J.A.; Spruit, J.H.M.; Rosenkranz, M.

1989-03-06

54

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

55

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

56

Magnetocrystalline anisotropy in R 2PdSi 3 (R=Tb, Dy, Ho, Er, Tm) single crystals  

Microsoft Academic Search

We present single crystal AC-susceptibility and magnetisation measurements of R2PdSi3 compounds with R=Tb, Dy, Ho, Er, and Tm. The crystal-electric field (CEF) parameter B20 and the value of the two-ion interaction exchange integral J(Q=0) are evaluated from the anisotropy of the AC-susceptibility measurements in the paramagnetic state. In addition, the magnetic anisotropy is investigated by magnetisation measurements well below the

M. Frontzek; A. Kreyssig; M. Doerr; M. Rotter; G. Behr; W. Löser; I. Mazilu; M. Loewenhaupt

2006-01-01

57

Magnetocrystalline anisotropy in R2PdSi3 (R=Tb, Dy, Ho, Er, Tm) single crystals  

Microsoft Academic Search

We present single crystal AC-susceptibility and magnetisation measurements of R2PdSi3 compounds with R=Tb, Dy, Ho, Er, and Tm. The crystal-electric field (CEF) parameter B20 and the value of the two-ion interaction exchange integral J(Q=0) are evaluated from the anisotropy of the AC-susceptibility measurements in the paramagnetic state. In addition, the magnetic anisotropy is investigated by magnetisation measurements well below the

M. Frontzek; A. Kreyssig; M. Doerr; M. Rotter; G. Behr; W. Löser; I. Mazilu; M. Loewenhaupt

2006-01-01

58

Magnetostriction ``jumps'' in twinned Tb0.3Dy0.7Fe1.9  

NASA Astrophysics Data System (ADS)

Large ``jumps'' in the magnetostriction have been observed in twinned single crystals of Tb0.3Dy0.7Fe1.9 (Terfenol-D) for magnetic fields parallel to the crystalline [112¯] direction. The interpretation of these large magnetostriction discontinuities is based upon a model of twinned dendritic Terfenol-D in which the magnetization of one twin jumps between two [111] directions while the magnetization of the remaining twin undergoes a continuous rotation of the magnetization. The field dependence of the magnetization and magnetostriction of cubic single crystals with ?111??100 was calculated using an expression which included the anisotropy constants K1 and K2 and compressive loads along [112¯]. With K1=-0.6 J/m3 and K2=-2.0 J/m3 (values appropriate for Terfenol-D near room temperature), magnetization ``jumping'' is predicted. For the twinned crystal, the jump in the magnetostriction was calculated to be greater than 1000 ppm. Because of this large magnetostriction, it is possible to configure a device to perform a substantial amount of work by the application of only a triggering magnetic field centered about an optimum bias field.

Clark, A. E.; Teter, J. P.; McMasters, O. D.

1988-04-01

59

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

NASA Astrophysics Data System (ADS)

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

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

2000-01-01

60

Crystal structures and reference powder patterns of BaRâZnOâ (R = La, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, and Tm)  

Microsoft Academic Search

Reference x-ray powder patterns and the crystal structures of the lanthanide compounds, BaRâZnOâ, in which R = La, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, or Tm were determined by the x-ray Rietveld refinement technique. A structural trend was confirmed for this series of compounds. The compounds with smaller ionic radii (R = Sm, Eu, Gd, Dy, Ho, Y,

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

1999-01-01

61

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

62

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

63

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

PubMed

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

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

2012-04-23

64

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

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

65

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

NASA Astrophysics Data System (ADS)

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

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

1999-06-01

66

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

67

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

68

Enhanced luminescence in Ln³?-doped Y?WO? (Sm, Eu, Dy) 3D microstructures through Gd³? codoping.  

PubMed

Microstructures of Y2WO6 were prepared by applying a hydrothermal synthesis in the presence of sodium dodecyl sulfate (SDS) surfactant, after which the materials were heat-treated at a temperature of 1100 °C. When prepared at pH 3, the spherical 3D microstructures were built from nanosized particles. Raising the pH gave materials built from differently shaped building blocks, which influenced the final architecture. These materials, similarly to other previously investigated and reported rare-earth tungstate materials, were found to show very interesting luminescence properties. However, quantum yield (QY) values have scarcely been reported for such materials. In this work, a detailed study of the photoluminescence characteristics, decay times, and quantum yields of Y2WO6 doped with Sm(3+), Eu(3+), and Dy(3+) is presented. When doped with different concentrations of Ln(3+) ions, the luminescence properties of the samples changed. The 2.5% Dy:Y2WO6 sample gave white-light emission and showed a QY of 17%. For the optimal lanthanide-ion concentrations, the systems were codoped with 2% and 10% Gd(3+) ions to test the possible enhancement of luminescence through energy transfer from W-O and/or Gd(3+) to Ln(3+). The Eu(3+),Gd(3+)-codoped system showed QYs as high as 79%. The Sm,Gd-codoped system showed the highest enhancement of QY. After incorporation of Gd(3+) ions, the 2.5% Sm_10% Gd:Y2WO6 materials showed a QY approximately 2.4 times larger than that of the 2.5% Sm:Y 2WO6 material. PMID:25166489

Kaczmarek, Anna M; Van Hecke, Kristof; Van Deun, Rik

2014-09-15

69

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

70

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

PubMed

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

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

2013-01-29

71

White light emission from spin coated Gd2O3:Dy nano phosphors synthesized using polyol technique.  

PubMed

Water dispersible Gd2O3:Dy3+ (2%) nanophosphors were synthesized through a facile polyol process and characterized by using X-ray diffraction (XRD), transmission electron microscopy (TEM), Dynamic Light Scattering (DLS) and photoluminescence (PL) spectrophotometry. The results of XRD, TEM and DLS show that resultant nanoparticles are single phasic and have spherical shape with 17 to 22% dispersibility. An efficient energy transfer was observed from host to the dopant ions. Characteristic blue and yellow emissions from Dy3+ ions were observed. The CIE coordinates of the nanophosphor lie in the white light region of the chromaticity diagram. Spin coating of the nanophosphor was done on quartz substrate. Bright white luminescence of this film was observed under ultraviolet light with lamda exc = 310 nm. PMID:21121321

Bedekar, Vinila; Dutta, Dimple P; Tyagi, A K

2010-12-01

72

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

SciTech Connect

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

Takahashi, M.; Yoshihara, A.; Shimamori, T.; Miyazki, T.; Wakiyama, T. (Tohoku Univ., Sendai (Japan))

1988-06-01

73

Fabrication, photoluminescence, and potential application in white light emitting diode of Dy3+-Tm3+ doped transparent glass ceramics containing GdSr2F7 nanocrystals  

NASA Astrophysics Data System (ADS)

Dy3+-Tm3+ doped transparent glass ceramics containing GdSr2F7 nanocrystals were fabricated successfully by a melt-quenching method and subsequent heating. X-ray diffraction and transmission electron microscopy analyses show that tetragonal GdSr2F7 nanocrystals are homogeneously precipitated among the borosilicate glass matrix. If excited with 354 nm UV light, the photoluminescence spectrum of Dy3+ single-doped transparent glass ceramics shows white-light emission. With doping of Tm3+, the overall emission color of Tm3+-Dy3+ co-doped transparent glass ceramics can be tuned from white to blue through energy transfer between Dy3+ and Tm3+. CIE chromaticity and color temperature measurements show that the resulting TGCS may be a candidate as a white LED material pumped by a UV InGaN chip.

Wang, X. F.; Yan, X. H.; Bu, Y. Y.; Zhen, J.; Xuan, Y.

2013-08-01

74

Device oriented magnetoelastic properties of Tb(x)Dy(1-x)Fe1.95 (x = 0.27, 0.3) at elevated temperatures  

NASA Astrophysics Data System (ADS)

In order to assess the potential of the higly magnetostrictive compound Terfenol-D (composition Tb(x)Dy(1-x)Fe1.95, where x = 0.3 or 0.27) for device applications in the temperature range 20-300 C, measurement of magnetostrictive strain (lambda), differential strain coeeficient (d(sub 33)), and magnetomechanical coupling coefficient (k(sub 33)) have been against applied dc field (less than or equal to 120 kA/m), uniaxial pressure (less than 20 MPa), and temperature. Comparing the two compositios at elevated temperatures has shown that large grain oriented material of the composition Tb0.3Dy0.7Fe1.95 has higher strains and d coefficient at elevated temperatures than small grain oriented material of composition Tb0.27Dy0.73Fe1.95, but for optimum coupling efficiency Tb0.27Dy0.73Fe1.95 is preferable.

Prajapati, K.; Greenough, R. D.; Jenner, A. G.

1994-11-01

75

Magnetostriction and anisotropy of twin-free single-crystals Tb0.5Dy0.5(Fe0.9Mn0.1)2  

NASA Astrophysics Data System (ADS)

A study of the effects of substituting a small amount of Mn for Fe in the Terfenol-D system is presented. The twin-free and <111>-oriented single-crystal rods of Tb0.5Dy0.5(Fe0.9Mn0.1)2 were prepared by Czochralski method. The magnetization, lattice constant, Curie temperature, and magnetostriction were examined. From the experimental results, it is possible to determine the effect of Mn substitution on magnetic anisotropy and magnetostriction. Because of Mn substituting for Fe, magnetic moment values of Tb0.5Dy0.5(Fe0.9Mn0.1)2 show two inflections and the easy magnetization directions also show changes from 1.5 to 300 K at an applied field of 1000 Oe. It strongly suggests that Mn substitution remarkably influences magnetocrystalline anisotropy of Tb0.5Dy0.5(Fe0.9Mn0.1)2. Its saturation magnetostrictions are 1.48×10-3 and 1.67×10-3, maximum d33 values are 1 and 1.5 under compressive stress of 0 and 12 MPa, respectively. These magnetostrictive properties are clearly better than those measured from the <112>-oriented twinned samples. This is the first time that the experimental data measured from the single-crystalline samples on the magnetic properties of Tb0.5Dy0.5(Fe0.9Mn0.1)2 are reported.

Wang, Jinghua; Wu, Guangheng; Zhao, Xuegen; Jia, Kechang; Zhan, Wenshan

1996-04-01

76

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

77

Synthesis and photoluminescence properties of Sm 3+ and Dy 3+ ions activated Ca 2 Gd 2 W 3 O 14 phosphors  

NASA Astrophysics Data System (ADS)

Rare earth ions (Sm 3+ and Dy 3+) activated calcium gadolinium tungstate [Ca 2Gd 2W 3O 14] powder phosphors were synthesized by solid state reaction method at 1000 °C. The obtained phosphors were characterized by XRD, SEM, EDAX, FTIR and PL spectroscopy. The results of XRD patterns indicate the tetragonal phase structure of Sm 3+ and Dy 3+: Ca 2Gd 2W 3O 14 phosphors. From the SEM images of Sm 3+ and Dy 3+: Ca 2Gd 2W 3O 14 phosphors, it is observed that the average grain size is in the range 100-250 nm. The functional groups are identified by using the FTIR spectra and the elements present in the composition are confirmed by the EDAX profiles. Emission spectra of Sm 3+: Ca 2Gd 2W 3O 14 powder phosphors have shown strong red emission at 646 nm ( 4G 5/2 ? 6H 9/2) with an excitation wavelength ?exci = 402 nm ( 6H 5/2 ? 4F 7/2) and Dy 3+: Ca 2Gd 2W 3O 14 phosphors have shown yellow emission at 574 nm ( 4F 9/2 ? 6H 13/2) with an excitation wavelength ?exci = 385 nm ( 6H 15/2 ? 4I 13/2).

Sailaja, S.; Dhoble, S. J.; Sudhakar Reddy, B.

2011-09-01

78

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) Å, b = 5.5973(2) Å and c = 7.6794(2) Å, and for Gd2MgTiO6a = 5.3143(5) Å, b = 5.5826(2) Å and c = 7.6324(2) Å. Samples morphology analyzed by scanning electron microscopy reveal strongly coupled grains with mean size 3 ?m. Paramagnetic behavior is evidenced by magnetic susceptibility measurements and Curie-Weiss fitting supplies effective magnetic moments which lay 98% in agreement with the theoretical predictions for the isolated rare earth elements for each compound.

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

2014-06-01

79

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

PubMed Central

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

2010-01-01

80

Magnetostriction and torque response of Tb0.5Dy0.5Fe2/Fe composites  

NASA Astrophysics Data System (ADS)

Equivolume composites of melt-spun Tb0.5Dy0.5Fe2 in an Fe matrix have been consolidated by hot pressing over a range of temperatures. We find that both the magnetic field dependence of the magnetostriction ?(H) and the torque response R? of these materials in a sensor configuration depend strongly on the consolidation temperature. As the hot press temperature increases, ?(H) becomes sharper, generating higher strains at lower applied fields, higher values of the maximum slope d?/dH, and more nearly saturated ?(H) at the maximum applied field of 19 kOe. These changes in magnetostriction are closely correlated with the observed response of the composites in a torque test. For a composite hot pressed at 755 °C we observe R?=6.3 G/100 ppm, a value which is twice that obtained for material consolidated at 550 °C and nearly a factor of three greater than the response of maraging steel.

Pinkerton, F. E.; Herbst, J. F.; Meyer, M. S.

2000-06-01

81

Large coercivity in anisotropy compensated Tb0.3Dy0.7Fe1.95 by microstructural refinement  

NASA Astrophysics Data System (ADS)

The anisotropy compensated Tb0.3Dy0.7Fe1.95 serves as an ideal alloy system to study the effect of microstructural refinement influencing coercivity. The cast alloy was melt spun and ball milled (with and without magnetic field) to impart microstructural refinement and correlated with the development of coercivity. Coercivity as high as 6500 Oe obtained during magnetic field assisted ball milling due to fine particle size, alignment of particles and strain. Coercivity of 1000 Oe obtained during melt spinning due to fine grain size and attacking faults on account of fast cooling. A comparative study highlighting coercivity mechanisms in the samples prepared by different routes has been highlighted in this paper.

Palit, Mithun; Chelvane, J. Arout; Basumatary, Himalay; Babu, D. Arvindha; Pandian, S.

2014-09-01

82

Dynamic writing of magnetic domains in GdTbFe: Observations made by Lorentz microscopy  

SciTech Connect

In this paper the sizes and shapes of thermally written magnetic domains in a GdTbFe layer are discussed. The magneto-optical layer is deposited on a specially prepared silicon wafer disk, provided with Si{sub 3}N{sub 4} windows. This allows dynamic writing of domains under realistic recording conditions on a rotating substrate and direct observation of the magnetization patterns in the transmission electron microscope, using Lorentz microscopy. Domain patterns were written in two different ways: With the first method, laser modulation (LM), the laser beam was modulated while applying a fixed field. In the second method, magnetic field modulation (MFM), the laser was on continuously and the applied magnetic field was modulated. With LM it was observed that both size and shape are closely dependent on the magnitude of the applied field. This behavior is in good agreement with observations made with optical readout of similar magneto-optical disks. Domains written with MFM have somewhat irregular contours. The degree of irregularity depends on the magnitude of the applied magnetic field and its switching time. Reduction of these irregularities can be achieved by simultaneously modulating the laser beam.

Greidanus, F.J.A.M.; Jacobs, B.A.J.; den Broeder, F.J.A.; Spruit, J.H.M. (Philips Research Laboratories, P.O. Box 80.000, 5600 JA, Eindhoven, The Netherlands (NL)); Rosenkranz, M. (Philips GmbH Forschungslaboratorium Hamburg, D-2000 Hamburg, Federal Republic of Germany (DE))

1989-11-15

83

119Sn Mössbauer spectroscopy of L?0.8L0.2Mn6Sn6 compounds (L?=Y, Gd, Tb; L=Gd-Tm, Lu)  

NASA Astrophysics Data System (ADS)

In the HfFe6Ge6-type ferrimagnetic compounds L?0.8L0.2Mn6Sn6 (L?=Y, Gd, Tb; L=Gd-Tm, Lu), the Sn2e and Sn2c sites surrounded by one or three lanthanide atoms split into different sub-sites depending on their (L?, L) environment. 119Sn Mössbauer spectroscopy evidences different hyperfine fields characterizing these sub-sites. The field differences are used to evaluate the contributions of the lanthanide moment to the hyperfine field. The analysis suggests isotropic and anisotropic contributions of the spin number of the lanthanide moment and dipolar contributions arising from its gJJ value. The lanthanide contribution is used to estimate the contribution of the manganese moment alone. The results are consistent with previous 119Sn Mössbauer spectroscopy measurements performed on isotypic compounds.

Venturini, G.; Lemoine, P.; Malaman, B.

2014-03-01

84

Electronic and magnetic structure of RScO{sub 3} (R=Sm,Gd,Dy) from x-ray spectroscopies and first-principles calculations  

SciTech Connect

The electronic structures of SmScO{sub 3}, GdScO{sub 3}, and DyScO{sub 3} are investigated by means of x-ray photoelectron spectroscopy, x-ray emission spectroscopy (XES), and x-ray absorption spectroscopy (XAS). A strong hybridization between Sc 3d and O 2p is found, and a contribution of the rare-earth 5d states to this hybridization is not excluded. The band gaps of the compounds are determined by combining XES and XAS measurements. For SmScO{sub 3}, GdScO{sub 3}, and DyScO{sub 3} the band gaps were determined to be 5.6, 5.8, and 5.9 eV, respectively. Magnetization versus temperature measurements reveal antiferromagnetic coupling at 2.96 (SmScO{sub 3}), 2.61 (GdScO{sub 3}), and 3.10 K (DyScO{sub 3}). For DyScO{sub 3} a Rietveld refinement of a 2 K neutron-diffraction data set gives the spin arrangement of Dy in the Pbnm structure (Shubnikov group: Pb{sup '}n{sup '}m{sup '})

Raekers, M.; Bartkowski, S.; Prinz, M.; Neumann, M. [Department of Physics, University of Osnabrueck, D-49069 Osnabrueck (Germany); Kuepper, K.; Potzger, K.; Zhou, S. [Institute of Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf, P.O. Box 51 01 19, D-01314 Dresden (Germany); Postnikov, A. V. [Laboratoire de Physique des Milieux Denses, Unversite Paul Verlaine, 1 Boulevard Arago, F-57078 Metz (France); Arulraj, A.; Stuesser, N. [Department of Magnetism, Hahn-Meitner-Institut, Berlin, Glienicker Strasse 100, 14109 Berlin (Germany); Uecker, R. [Institute for Crystal Growth, Max-Born-Street 2, D-12489 Berlin (Germany); Yang, W. L. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2009-03-15

85

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

PubMed

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

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

2012-10-15

86

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

SciTech Connect

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

Herchenroeder, J.W.

1989-02-01

87

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 Å. The ET mechanism from Ce3+ to Tb3+ ions was proved to be dipole-dipole interaction. The developed phosphor exhibits a strong excitation in UV spectral region and high efficient ET from Ce3+ to Tb3+ ions. It may find applications as a green light-emitting UV-convertible phosphor in white LED devices. Furthermore, a white light emission phosphor Ba3Gd(PO4)3: Ce3+, Tb3+, Mn2+ was also investigated.

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

2014-03-01

88

Modulating the magnetic properties by structural modification in a family of Co-Ln (Ln = Gd, Dy) molecular aggregates.  

PubMed

Two types of heterometallic aggregates of the general formula [(Co(II))3(Co(III))2Ln3(?3-OH)5(O2C(t)Bu)12(L)2]·2H2O (Ln = Gd(III) (), Dy(III) ()) and [(Co(III))3Ln3(?3-OH)4(O2C(t)Bu)6(L)3](NO3)2·2CH3CN·2H2O (Ln = Gd(III) (), Dy(III) ()) were successfully isolated in reactions with [Co2(?-OH2)(O2C(t)Bu)4]·(HO2C(t)Bu)4, Ln(NO3)3 and n-N-butyldiethanolamine (H2L) under ambient conditions by a change in the stoichiometry of the reactants from 1?:?1?:?1 to 1?:?1?:?2 in order. Bond Valence Sum (BVS) calculations and bond lengths indicate the presence of mixed valent Co (Co(II), Co(III)) centres in compounds and and only Co(III) centres in and as required for the charge balances and supported by the magnetic measurements. Isostructural crab shaped complexes and feature distorted cubane cores that edge share to each other whereas the metallic core of or displays hemicubane like arrangement of metal centres and oxygen atoms. Overall structural symmetry was found to enhance on moving from the former to the latter series of complexes. Magnetic studies reveal significant magnetic entropy changes for complexes and (-?Sm = 21.57 and 19.39 J kg(-1) K(-1)) and single molecular magnetic behaviour for and . PMID:25135438

Sheikh, Javeed Ahmad; Goswami, Soumyabrata; Konar, Sanjit

2014-10-21

89

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

Microsoft Academic Search

Dark red single crystals of PrLnYbS (Ln = Pr\\/Yb, Tb, Dy) have been synthesized through the reaction of elemental rare earth metals and S using a SbS flux at 1000 C. These isotypic compounds adopt the F-LnS3 three-dimensional open channel structure type. Eight-coordinate Pr{sup 3+} ions sit in the channels, which are constructed from three different edge-shared double chains running

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

2008-01-01

90

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

91

Magnetocaloric effect of mononitride containing gadolinium and dysprosium Gd x Dy 1? x N  

Microsoft Academic Search

The binary rare-earth mononitride, GdxDy1?xN, was synthesized by carbothermic reduction performed in a nitrogen gas stream. A continuous solid solution with the NaCl structure was observed through the whole composition range, and the Curie temperature was found to vary from 61 to 21 K as x changes from 1 to 0. The magnetocaloric effect was evaluated as a function of

Takashi Nakagawa; Kengo Sako; Takayuki Arakawa; Takao A Yamamoto

2004-01-01

92

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

93

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

SciTech Connect

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

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

2007-09-15

94

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

95

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, Sébastien; Picard, Claude; Muller, Robert N

2014-01-01

96

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

97

Magnetic and magneto-optical properties of rare-earth transition-metal alloys containing Gd, Tb, Fe, Co  

SciTech Connect

Binary and ternary amorphous rare-earth transition-metal alloys of general composition RE/sub 1/minus//ital x//(Fe/sub 1/minus//ital y//Co/sub /ital y//)/sub /ital x// with RE=Gd, Tb and 0/lt//ital x//lt/1, 0less than or equal to/ital y/less than or equal to1 were prepared by evaporation. The saturation magnetization, uniaxial anisotropy, and Faraday rotation were investigated as a function of composition and temperature. Also, from the temperature-dependent measurements the compositional variation of the Curie temperature and the compensation temperature were determined. The experimental data have been analyzed in terms of the mean-field theory yielding spin values and effective exchange interaction energies. The compositional variation of the spin value was described by the environment model. The anisotropy data were fitted with a dipolar equation using the sublattice magnetizations inferred from the mean-field analysis. The magneto-optical effects are primarily caused by the transition metals. For the binaries GdFe and GdCo the compositional variation of the Kerr rotation typically peaks between 1000 and 1500 nm. The lowest magneto-optical effects for binary RE-Th alloys with respect to composition are reached at about /ital x/approx.0.5 for /ital T/=4.2 K. The temperature dependence of the Faraday rotation can be well described in terms of the sublattice magnetizations.

Hansen, P.; Clausen, C.; Much, G.; Rosenkranz, M.; Witter, K.

1989-07-15

98

Bifunctional mixed-lanthanide cyano-bridged coordination polymers Ln(0.5)Ln'(0.5)(H2O)5[W(CN)8] (Ln/Ln' = Eu3+/Tb3+, Eu3+/Gd3+, Tb3+/Sm3+).  

PubMed

A new family of mixed-lanthanide cyano-bridged coordination polymers Ln(0.5)Ln'(0.5)(H(2)O)(5)[W(CN)(8)] (where Ln/Ln' = Eu(3+)/Tb(3+), Eu(3+)/Gd(3+), and Tb(3+)/Sm(3+)) containing two lanthanide and one transition metal ions were obtained and characterized by X-ray diffraction, photoluminescence spectroscopy, magnetic analyses, and theoretical computation. These compounds are isotypical and crystallize in the tetragonal system P4/nmm forming two-dimensional grid-like networks. They present a magnetic ordering at low temperature and display the red Eu(3+) ((5)D(0) ? (7)F(0-4)) and green Tb(3+) ((5)D(4) ? (7)F(6-2)) characteristic photoluminescence. The Tb(0.5)Eu(0.5)(H(2)O)(5)[W(CN)(8)] compound presents therefore green and red emission and shows Tb(3+)-to-Eu(3+) energy transfer. PMID:22849813

Chelebaeva, Elena; Long, Jérôme; Larionova, Joulia; Ferreira, Rute A S; Carlos, Luis D; Almeida Paz, Filipe A; Gomes, José B R; Trifonov, Alexander; Guérin, Christian; Guari, Yannick

2012-08-20

99

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

NASA Astrophysics Data System (ADS)

The potassium lanthanide double sulphates K Ln(SO 4) 2·H 2O ( Ln=La, Nd, Sm, Eu, Gd, Dy) were obtained by evaporation of aqueous reaction mixtures of rare earth (III) sulphates and potassium thiocyanate at 298 K. X-ray single-crystal investigations show that K Ln(SO 4) 2·H 2O ( Ln=Nd, Sm, Eu, Gd, Dy) crystallise monoclinically ( Ln=Sm: P2 1/ c, Z=4, a=10.047(1), b=8.4555(1), c=10.349(1) Å, w R2=0.060, R1=0.024, 945 reflections, 125 parameters) while KLa(SO 4) 2·H 2O adopts space group P3 221 (Z=3, a=7.1490(5), c=13.2439(12) Å, w R2=0.038, R1=0.017, 695 reflections, 65 parameters). The coordination environment of the lanthanide ions in K Ln(SO 4) 2·H 2O is different in the case of the Nd/Sm/Gd and the Eu/Dy compounds, respectively. In the first case the Ln atoms are nine-fold coordinated in contrast to the latter where the Ln ions are eight-fold coordinated by oxygen atoms. The vibrational spectra of K Ln(SO 4) 2·H 2O and the UV-vis reflection spectra of KEu(SO 4) 2·H 2O and KNd(SO 4) 2·H 2O are also reported.

Kazmierczak, Karolina; Höppe, Henning A.

2010-09-01

100

Magnetic properties of amorphous Gd{sub 70}(Fe,Ni){sub 30} and Dy{sub 70}(Fe, Ni){sub 30} alloys  

SciTech Connect

The unique physical and mechanical properties of amorphous materials make them attractive for magnetic refrigeration applications. In an effort to develop advanced magnetic refrigerants, the magnetic properties of amorphous Gd{sub 70}(Fe,Ni){sub 30} and DY{sub 70}(Fe,Ni){sub 30} alloys were investigated. The combination of 70 at.% Gd or Dy with different ratios of Fe and Ni produced amorphous materials with ordering temperatures covering the range of 300 K to 35 K. The coercive forces of both Gd-based and Dy-based alloys were negligible near their ordering temperatures. The magnetization properties of the alloys as a function of temperature in applied fields up to 5.6 x 10{sup 6} A/m are presented. Magnetic entropy changes obtained from the field-dependent magnetization data are discussed. The broad nature of magnetic transitions in the amorphous alloys and its impact on the suitability of these materials as magnetic refrigerants are also discussed.

Liu, X.Y.; Barclay, J.A. [Univ. of Victoria, British Columbia (Canada); Gopal, B.R. [Universite du Quebec (Canada)] [and others

1997-06-01

101

Domain observation and magnetostriction in Tb0.3Dy0.7Fe2 twinned single crystals  

NASA Astrophysics Data System (ADS)

The ternary alloy Tb0.3Dy0.7Fe2 (Terfenol-D) exhibits the largest known magnetostriction to anisotropy ratio near room temperature. To better determine the interaction between the elastic and magnetic properties of this material, a stoichiometric twinned single crystal was grown by a free-standing float-zone technique. Observations using Scanning electron microscopy and energy dispersive spectroscopy confirmed that the sample was free of the normally present rare-earth (RE) eutectic phase and simultaneously free of Widmanstatten precipitate (RE Fe3). A bar with (111) and (11¯0) faces perpendicular to the [112¯] growth direction was examined. Also, a [111¯] slab was cut from the boule. This slab was studied along the [111¯] and [11¯0] directions with prestress applied along the [111¯]. This is the first report of the effects of applying prestress and magnetic fields in a direction not collinear with the [112¯] growth direction. From magnetization (M) and magnetostriction (?) measurements as a function of field, prestress, and temperature, we determined the hysteresis and saturation parameters. These measurements do not indicate the [11¯0] ? and M behaviors found previously for RE-rich Terfenol-D. Domain observations with differential phase contrast and x-ray topography have shown different orientations in the twin and parent sections of the [111¯] specimen. The observed structures can be interpreted as arising from domains with magnetization components normal to the surface. The domain observations on the (111) and (11¯0) bar faces and on the [111¯] slab correlate with each other with respect to orientations and domain interpretations.

Teter, J. P.; Mahoney, K.; Al-Jiboory, M.; Lord, D. G.; McMasters, O. D.

1991-04-01

102

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

103

The role of wall coercivity and energy on the read-out stability of GdTb-Fe based magneto-optical disks  

SciTech Connect

The read-out stability of thermomagnetically written domains in GdTb-Fe disks have been measured by recording experiments as a function of read laser power and the applied magnetic field. The domain stability increases significantly and the field dependence becomes much flatter with increasing Tb content. At low Tb content compensation temperatures below room temperature result in a strong reduction of domain stability at higher applied magnetic fields. The results of a bubble-like model using the measured magnetic and thermal properties of the disks explain and predict the recording data with high precision.

Klahn, S.; Raasch, D. (Philips Research Lab., 2000 Hamburg 54 (DE))

1990-09-01

104

Influence of rare earth elements (Y, Gd and Lu) on the luminescent properties of green phosphor ZnMoO4 :Tb(3+).  

PubMed

(Zn,Lnx )MoO4 :Tb(3+) (Ln?=?Y(3+) , Gd(3+) and Lu(3+) ) were prepared using the co-precipitation method. Phase impurity, morphology and composition were investigated by power X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The experimental results show that crystal structure is not destroyed after doping an appropriate amount of Y(3+) , Gd(3+) and Lu(3+) . EDS analysis reveals that Y, Gd and Lu have been successfully doped into ZnMoO4 . In addition, the morphology of the phosphors is notably improved, exhibiting homogeneous dispersion morphology and irregular shapes of particle size?~?0.5-1 µm. The luminescent intensity of (Zn,Lnx )MoO4 :Tb(3+) (Ln?=?Y(3+) , Gd(3+) and Lu(3+) ) phosphor is obviously higher than that of ZnMoO4 :Tb(3+) phosphor. The energy transfer process between trivalent rare earth ions indicates that the inert earth ions can act as an energy bridge from MoO4 (2-) to Tb(3+) . Copyright © 2013 John Wiley & Sons, Ltd. PMID:24282116

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

2014-11-01

105

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

106

Crystal growth, structures, magnetic and photoluminescent properties of NaLnGeO4 (Ln = Sm, Eu, Gd, Tb)  

NASA Astrophysics Data System (ADS)

Single crystals of NaLnGeO4 (Ln = Sm, Eu, Gd) were grown out of a molten sodium hydroxide flux, and their crystal structures were determined by single crystal X-ray diffraction. The lanthanide containing germanates crystallize in the orthorhombic space group of Pnma, and exhibit a complex three-dimensional structure consisting of corner- or edge-shared LnO6, GeO4, and NaO6 polyhedra. UV-vis diffuse reflectance spectra indicated that the reported oxides are insulating materials with wide band gaps. The magnetic susceptibility data shows paramagnetic behavior. For the NaEuGeO4 and NaTbGeO4 compositions intense room temperature photoluminescence was observed.

Yeon, Jeongho; Hardaway, John B.; Sefat, Athena S.; Latshaw, Allison M.; zur Loye, Hans-Conrad

2014-08-01

107

Syntheses, structure, magnetism, and optical properties of the partially ordered quaternary interlanthanide sulfides PrLnYb2S6 (Ln=Tb, Dy)  

Microsoft Academic Search

Dark red single crystals of PrLnYb2S6 (Ln=Pr\\/Yb, Tb, Dy) have been synthesized through the reactions of elemental rare earth metals and S using a Sb2S3 flux at 1000 °C. These isotypic compounds adopt the F-Ln2S3 three-dimensional open-channel structure type. Eight-coordinate Pr3+ ions sit in the channels that are constructed from three different edge-shared double chains running down the b-axis that

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

2007-01-01

108

Syntheses, structure, magnetism, and optical properties of the partially ordered quaternary interlanthanide sulfides Pr LnYb 2S 6 ( Ln=Tb, Dy)  

Microsoft Academic Search

Dark red single crystals of PrLnYb2S6 (Ln=Pr\\/Yb, Tb, Dy) have been synthesized through the reactions of elemental rare earth metals and S using a Sb2S3 flux at 1000°C. These isotypic compounds adopt the F-Ln2S3 three-dimensional open-channel structure type. Eight-coordinate Pr3+ ions sit in the channels that are constructed from three different edge-shared double chains running down the b-axis that contain

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

2007-01-01

109

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

PubMed

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

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

2014-12-10

110

Synthesis, optical properties, and energy transfer of Ce3+/Tb3+ co-doped MyGdFx (M = Li, Na, K)  

NASA Astrophysics Data System (ADS)

Through a solid-state reaction method, the Ce3+/Tb3+ co-doped MyGdFx (M = Li, Na, K; x = 3, 4, 6; y = 0, 1, 3) system samples have been synthesized by controlling the annealing temperatures and the ratios of raw materials. The samples were characterized by X-ray diffraction (XRD) patterns, photoluminescence (PL) excitation and emission spectra as well as luminescent dynamic decay curves. The experimental results suggest that the LiF is more difficult to react with the prepared material compared that of NaF or KF under similar reaction conditions. The samples crystallized in different crystalline phases. The energy transfer from Ce3+ to Tb3+ or Ce3+ to Gd3+ to Tb3+ has been observed in all the samples. The Ce3+ and Tb3+ present different optical properties for they are sensitive to the local environment. In addition, the deduced lifetime of Tb3+5D4 ? 7F5 transition decreases in the same system samples with the annealing temperature increasing. The deduced lifetime of Tb3+5D4 ? 7F5 also decreases with the increase of the KF concentration in the KF system samples.

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

2014-12-01

111

Magnetostriction and hysteresis of lang1 1 0rang oriented Tb0.29Dy0.48Ho0.23Fe2 single crystal  

NASA Astrophysics Data System (ADS)

Magnetostriction behaviour and magnetostriction hysteresis of the single crystal alloy Tb0.29Dy0.48Ho0.23Fe2 are investigated experimentally and theoretically. The oriented lang1 1 0rang single crystals of the magnetostrictive alloy Tb0.29Dy0.48Ho0.23Fe2 are successfully prepared by the optical floating zone melting method. The single crystals are characterized by optical metallography, x-ray diffraction and x-ray Laue back-reflection measurement. The giant magnetostrictive properties are achieved in a wide operating temperature range from -60 to 80 °C. The calculated magnetostriction of the present alloy is reduced by only 6%, but the magnetostriction hysteresis (Wh) is reduced by more than 30%, compared with the traditional Terfenol-D giant magnetostrictive alloy. The magnetostriction behaviour is modelled using phenomenological theory. The rotation paths of magnetic domain moments are mathematically calculated and hence the resultant magnetostriction is obtained. The theoretical model of magnetostriction hysteresis Wh is proposed and the intrinsic factors of Wh are determined, which can well explain the pre-stress and temperature dependence of magnetostriction hysteresis.

Jiang, Chengbao; Zhang, Hongbo; Wang, Zhibin; Xu, Huibin

2008-08-01

112

Exchange Interactions at the Origin of Slow Relaxation of the Magnetization in {TbCu3} and {DyCu3} 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 Mtot 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

113

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

114

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

SciTech Connect

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

Vijaya Kumar, B.; Velchuri, Radha; Rama Devi, V. [Department of Chemistry, Osmania University, Hyderabad 500 007 (India); Sreedhar, B. [Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Hyderabad 500 007 (India); Prasad, G. [Department of Physics, Osmania University, Hyderabad 500 007 (India); Jaya Prakash, D. [College of Technology, Osmania University, Hyderabad 500 007 (India); Kanagaraj, M.; Arumugam, S. [Centre for High Pressure Research, School of Physics, Bharathidasan University, Tiruchirapalli 620 024 (India); Vithal, M., E-mail: muga_vithal@osmania.ac.i [Department of Chemistry, Osmania University, Hyderabad 500 007 (India)

2011-02-15

115

Magnetic and optical properties of rare earth doped Sn0.95RE0.05O2-? (RE =Gd, Dy, Er)  

NASA Astrophysics Data System (ADS)

The magnetic and optical properties of rare earth (Gd, Dy, and Er) ion doped SnO2 bulk and optical properties of thin films are investigated. The bulk samples were found to show an upturn in ac magnetic susceptibility at low temperatures TU and exhibited a paramagnetic moment at room temperature. The band gap of the bulk samples was found to be independent of the rare earth (RE) ions while for the thin films it varied from 3.48 eV to 3.58 eV. The observed low temperature upturn suggests an interesting magnetic property in SnO2 with RE doping.

Mohan Kant, K.; Chandrasekaran, K.; Ogale, S. B.; Venkatesan, T.; Sethupathi, K.; Rao, M. S. R.

2005-05-01

116

Fabrication and comparison Gd2O2S(Tb) and CsI(Tl) films for X-ray imaging detector application  

Microsoft Academic Search

During the last decade, digital X-ray imaging systems have been replacing analog X-ray imaging systems of conventional X-ray film-screen combination for radiography applications. Indirect detection methods consisted of an X-ray converter (or a scintillator film) and photodiode arrays are more widely used in medical diagnoses and industrial fields. Two major scintillation materials such as terbium doped gadolinium oxysulfide (Gd2O2S:Tb, GOS)

Bo Kyung Cha; Jeong-Hyun Shin; Jong Yul Kim; Hosang Jeon; Jun Hyung Bae; Cha-hun Lee; Sungho Chang; Hyoungtaek Kim; Byoung-Jik Kim; Gyuseong Cho

2008-01-01

117

Magnetostrictive properties of Tb0.24Dy0.76Fe2-xNix thin films for wireless micro actuators and application to array type micro transporter  

NASA Astrophysics Data System (ADS)

In this paper, wireless optical system was developed by using array type TbDyFeNi thin film actuator. The effect of Ni content on the magneto-mechanical properties of the Tb0.24Dy0.76Fe2 system, for wireless micro actuator with the effect of deposited film thickness of TbDyFeNi on silicon substrate, was also investigated. To create the device, array shape silicon substrates were bulk micromachined, and Tb0.24Dy0.76Fe2-xNix, (x=0, 0.5, 1.2, 2.0) films were sputter-deposited on the back side of substrate by selective DC magnetron sputtering techniques. After the sputter process, magnetization and effective mgnetoelastic coupling coefficient and magnetostriction of the sample were measured for the magnetomechanical characterizaztion. For the operation, each branch of the array type actuator has different length and out-ofplane motion. Each branch was actuated by externally applied magnetic fields up to 0.5T and motion of the branches made inclined movement. As a result, deflected angle of the actuator due to the movement of array type actuator to external magnetic fields were observed.

Lee, Heung-Shik; Kim, Bongjun; Cho, Chongdu

2010-04-01

118

The luminous and magnetic properties of Tb3+-doped four angle star-like NaGd(WO4)2.  

PubMed

Four angle star-like double tungstates NaGd(WO4)2 have been prepared hydrothermally with cetyl trimethyl ammonium bromide (CTAB) as the chelating agent and ethanol as the mixing solvent. Monodisperse micron-sized four angle star-like NaGd(WO4)2 were fabricated for the first time. The samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and vibrating sample magnetrometer (VSM) techniques. This work emphasizes the luminescence properties of Tb(3+)-doped NaGd(WO4)2 under ultraviolet (UV) and vacuum ultraviolet (VUV) excitation and the magnetic properties. The results demonstrate the phosphors are expected to have potential applications in weak lighting systems and magnetic resonance imaging. PMID:24734626

Xin, Shuangyu; Wang, Yuhua; Lil, Fenghua; Liu, Bitao; Zhang, Jia; Tao, Ye

2014-05-01

119

Tunable-Color Luminescence via Energy Transfer in NaCa13/18Mg5/18PO4:A (A = Eu(2+)/Tb(3+)/Mn(2+), Dy(3+)) Phosphors for Solid State Lighting.  

PubMed

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

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

2014-11-17

120

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

121

Single-Component and Warm-White-Emitting Phosphor NaGd(WO4)2:Tm(3+), Dy(3+), Eu(3+): Synthesis, Luminescence, Energy Transfer, and Tunable Color.  

PubMed

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

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

2014-11-01

122

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

SciTech Connect

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

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

2010-02-15

123

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

124

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

PubMed

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

2003-07-01

125

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

PubMed

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

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

2012-02-20

126

Metal-insulator transitions, structural and microstructural evolution of RNiOâ (R = Sm, Eu, Gd, Dy, Ho, Y) perovskites: Evidence for room-temperature charge disproportionation in monoclinic HoNiOâ and YNiOâ  

Microsoft Academic Search

RNiOâ nickelates have been prepared under high oxygen pressure (R = Sm, Eu, Gd) or high hydrostatic pressure (R = Dy, Ho, Y) in the presence of KClOâ. The samples have been investigated at room temperature (RT) by synchrotron X-ray powder diffraction to follow the evolution of the crystal structures and microstructures along the series. The distortion of the orthorhombic

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

1999-01-01

127

Über die mischbarkeit von uc mit LaN, CeN, PrN, NdN, SmN, GdN, DyN und ErN  

NASA Astrophysics Data System (ADS)

ZusammenfassungThe miscibility of UC with LaN, CeN, PrN, NdN, SmN, GdN, DyN and ErN has been investigated. X-ray studies of the mixed nitride phases indicate miscibility in all cases with one exception in the system UC-LaN.

Ettmayer, Peter; Waldhart, Johann; Vendl, Alfred; Banik, Gerhard

1980-07-01

128

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

PubMed

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

Zheng, Yuhui; Lin, Jintai; Wang, Qianming

2012-10-01

129

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

NASA Astrophysics Data System (ADS)

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

Bu, Junfu; Jönsson, Pär G.; Zhao, Zhe

2014-12-01

130

Thermoelectric and Magnetic Properties of Ca0.98RE0.02MnO3- ? (RE = Sm, Gd, and Dy)  

NASA Astrophysics Data System (ADS)

Polycrystalline samples of Ca0.98RE0.02MnO3- ? (RE = Sm, Gd, and Dy) have been prepared by conventional solid-state reactions and their properties measured at 300 K to 700 K. All samples were single phase with orthorhombic structure. The average valence and oxygen content of Ca0.98RE0.02MnO3- ? were determined by iodometric titration. Doping at the Ca site by rare-earth metals causes a strong decrease of electrical resistivity due to the creation of charge carrier content by Mn3+ in the Mn4+ matrix, as evidenced by iodometric titration results. The Seebeck coefficient of all the samples was negative, indicating that the predominant carriers are electrons over the entire temperature range. Among the doped samples, Ca0.98Dy0.02MnO3- ? had the highest dimensionless figure of merit of 0.073 at 612 K, representing an improvement of about 115% with respect to the undoped CaMnO3- ? sample at the same temperature. All the samples exhibited an antiferromagnetic transition with Néel temperature of around 120 K. Magnetization measurements indicated that Ca0.98RE0.02 MnO3- ? samples exhibited a high-spin state of Mn3+.

Bhaskar, Ankam; Liu, Chia-Jyi; Yuan, J. J.

2012-09-01

131

Structure and properties of Gd3Ge4: the orthorhombic RE3Ge4 structures revisited (RE = Y, Tb-Tm).  

PubMed

The new binary compound Gd(3)Ge(4) has been synthesized and its structure has been determined from single-crystal X-ray diffraction. Gd(3)Ge(4) crystallizes in the orthorhombic space group Cmcm (No. 63) with unit cell parameters a = 4.0953(11) A, b = 10.735(3) A, c = 14.335(4) A, and Z = 4. Its structure can be described as corrugated layers of germanium atoms with gadolinium atoms enclosed between them. The bonding arrangement in Gd(3)Ge(4) can also be derived from that of the known compound GdGe (CrB type) through cleavage of the (infinity)(1)[Ge(2)] zigzag chains in GdGe and a subsequent insertion of an extra germanium atom between the resulting triangular fragments. Formally, these characteristics represent isotypism with the Er(3)Ge(4) type (Pearson's oC28). However, re-examination of the crystallography in the whole RE(3)Ge(4) series (RE = Y, Tb-Tm) revealed discrepancies and called into question the accuracy of the originally determined structures. This necessitated a new rationalization of the bonding, which is provided in the context of a comparative discussion concerning both the original and revised structure models, along with an analysis of the trends across the series. The temperature dependence of the magnetic susceptibility of Gd(3)Ge(4) shows that it is paramagnetic at room temperature and undergoes antiferromagnetic ordering below 29 K. Magnetization, resistivity, and calorimetry data for several other members of the RE(3)Ge(4) family are presented as well. PMID:17877339

Tobash, Paul H; DiFilippo, Gary; Bobev, Svilen; Hur, Namjung; Thompson, Joe D; Sarrao, John L

2007-10-15

132

X-ray diffraction investigation of the system Gd-Co-P  

SciTech Connect

This paper investigates the system Gd-Co-P with the aim of constructing the equilibrium phase diagrams. In the system Gd-Co-P there are no solid solutions based on binary compounds. The thermodynamically most stable compound GdP is in equilibrium with all the binary and ternary compounds. The investigation reveals compounds with the structural type of Hf/sub 2/Co/sub 4/P/sub 3/ of the composition R/sub 2/Co/sub 4/P/sub 3/ (R = Ce, Pr, Nd, Sm, Tb, Dy, Ho, Er, Tm, Yb, Lu).

Kuz'ma, Y.B.; Davydov, V.N.; Ovod, M.R.

1986-09-01

133

A new family of Pb-based 1222 cuprates Pb(Sr,La) 2Ln 2Cu 2O z (Ln?Gd, Dy, Eu, and Pr)  

NASA Astrophysics Data System (ADS)

A series of new Pb-based 1222 cuprates of the general formula Pb(Sr,La) 2Ln 2Cu 2O z (Ln?Gd, Dy, Eu, and Pr) has been reported in this paper. In this kind of compounds, cations in the rock-salt-type monolayer completely consist of Pb ions, but the iodometric titration results indicate that the Pb ions in the rock-salt-type monolayer actually exist in the form of mixed valence states, i.e., Pb 4+ and Pb 2+, and the proportion of Pb 4+ and Pb 2+ is close to 1:1. The Pb-1222 phases Pb(Sr 2- xLa x)Ln 2Cu 2O z are very sensitive to sintering temperature and atmosphere, as well as the Sr content. For example, pure Pb-1222 can be only obtained at 920°C in air for the composition Pb(Sr 1.2La 0.8)Gd 2Cu 2CO z. All these Pb-1222 phases are not superconducting.

Min, J. R.; Liang, J. K.; Jin, H.; Wang, C.; Chen, H.; Yu, Y. D.; Dong, C.; Rao, G. H.

1995-02-01

134

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

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

135

Self-assembled 3D sphere-like SrMoO4 and SrMoO4:Ln3+ (Ln=Eu, Sm, Tb, Dy) microarchitectures: facile sonochemical synthesis and optical properties.  

PubMed

Three-dimensional (3D) well-defined SrMoO4 and SrMoO4:Ln(3+) (Ln=Eu, Sm, Tb, Dy) hierarchical structures of obvious sphere-like shape have been successfully synthesized using a large-scale and facile sonochemical route without using any catalysts or templates. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), and photoluminescence (PL) spectra were used to characterize the samples. The intrinsic structural feature of SrMoO4 and external factor, namely the ultrasonic time and the pH value, are responsible for the ultimate shape evolutions of the product. The possible formation mechanism for the product is presented. Additionally, the PL properties of SrMoO4 and SrMoO4:Ln(3+) (Ln=Eu, Sm, Tb, Dy) hierarchical structures were investigated in detail. The Ln(3+) ions doped SrMoO4 samples exhibit respective bright red-orange, yellow, green and white light of Eu(3+), Sm(3+), Tb(3+) and Dy(3+) under ultraviolet excitation, and have potential application in the field of color display. Simultaneously, this novel and efficient pathway could open new opportunities for further investigating about the properties of molybdate materials. PMID:24746510

Zhang, Junjun; Li, Ruiqing; Liu, Lu; Li, Linlin; Zou, Lianchun; Gan, Shucai; Ji, Guijuan

2014-09-01

136

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

137

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. Copyright © 2013 John Wiley & Sons, Ltd. PMID:24222272

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

2014-09-01

138

Anisotropic magnetostriction in a <110> oriented crystal Tb0.36Dy0.64(Fe0.85Co0.15)2 after coaxial field annealing  

NASA Astrophysics Data System (ADS)

Axial magnetostriction of Terfenol-D oriented crystals is highly anisotropic when changing the magnetization direction. Magnetostrictions of a ?110? oriented crystal Tb0.36Dy0.64(Fe0.85Co0.15)2 were investigated under magnetic fields with a series of angles ? to its axis. Totally different anisotropic magnetostrictive behaviors are observed after annealing under a coaxial field of 240 kA/m. The magnetostriction for the field annealed specimen seems unsaturated even under 640 kA/m for angles ? in the range from 0° to 55°. At these angles, magnetostriction "ascending" is observed during the final magnetization process, while magnetostriction "dropping" occurs at angles above 35° for the untreated crystal. With the increase in angle ?, the corresponding field where magnetostriction starts dropping decreases for the untreated crystal, while the field at which magnetostriction starts ascending increases for the field annealed one. A simplified model based on moment "jump" and "rotation" is proposed to explain such anisotropic behaviors.

Zhang, Changsheng; Ma, Tianyu; Qi, Ruilei; Yan, Mi

2010-08-01

139

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

140

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

141

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

PubMed

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

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

2013-08-14

142

Realization of tunable emission via efficient Tb3+-Eu3+ energy transfer in K3Gd(PO4)2 for UV-excited white light-emitting-diodes  

NASA Astrophysics Data System (ADS)

A n-UV convertible phosphor K3Gd(PO4)2:Tb3+, Eu3+ with tunable-emitting color has been synthesized by the solid state reaction. Under the Tb3+ excitation (373 nm), the Eu3+ emissions increase dramatically with increasing the Eu3+ content due to the efficient energy transfer from Tb3+ to Eu3+, which has been justified through the luminescence spectra and fluorescence decay curves. K3Gd(PO4)2:0.5Tb3+, yEu3+ can achieve tunable color emissions from yellowish-green through orange-yellow and ultimately to reddish-orange by simply adjusting the Eu3+ content. In addition, the energy transfer mechanism was demonstrated to be the dipole-dipole interaction and the energy transfer efficiency was calculated. The present results indicate that this novel orange-yellow emitting phosphor can be as a potential candidate for the application in white LEDs.

Jiang, Tingming; Yu, Xue; Xu, Xuhui; Yu, Hongling; Zhou, Dacheng; Qiu, Jianbei

2014-01-01

143

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

144

Suppression of the superconducting transition of RFeAsO1-xFx ( R=Tb , Dy, and Ho)  

NASA Astrophysics Data System (ADS)

A suppression of superconductivity in the late rare-earth RFeAsO1-xFx materials is reported. The maximum critical temperature (Tc) decreases from 51 K for R=Tb to 36 K for HoFeAsO0.9F0.1 , which has been synthesized under 10 GPa pressure. This suppression is driven by a decrease in the Fe-As-Fe angle below an optimum value of 110.6° , as the angle decreases linearly with unit-cell volume (V) across the RFeAsO1-xFx series. A crossover in electronic structure around this optimum geometry is evidenced by a change in sign of the compositional dTc/dV , from negative values for previously reported large R materials to positive for HoFeAsO0.9F0.1 .

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

2009-08-01

145

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

146

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

147

Synthesis and crystal chemistry of the new compounds GdBa{sub 4}Cu{sub 3}O{sub 8.5+{delta}} and DyBa{sub 4}Cu{sub 3}O{sub 8.5+{delta}}  

SciTech Connect

Two new compounds, GdBa{sub 4}Cu{sub 3}O{sub 8.5+{delta}} (Gd143) and DyBa{sub 4}Cu{sub 3}O{sub 8.5+{delta}} (Dy143), were synthesized from precursors Gd{sub 2}O{sub 3}, Dy{sub 2}O{sub 3}, BaO{sub 2}, and CuO at 1000&hthinsp;{degree}C in an oxygen atmosphere. The oxygen stoichiometric value {delta} was found to be 0.68 for Gd143 and 0.6 for Dy143 by iodometric titration. Rietveld refinement of x-ray powder diffraction data showed that Gd143 belongs to the space group {ital Pm}3 while Dy143 belongs to the space group {ital P}23. The two space groups, {ital Pm}3 and {ital P}23, are very similar. Their main difference is that {ital P}23 does not have the inversion symmetry of {ital Pm}3. Both compounds have a cubic unit cell with a lattice parameter of 8.16528thinsp{plus_minus}thinsp0.00006thinsp{Angstrom} for Gd143 and 8.10807thinsp{plus_minus}thinsp0.00010thinsp{Angstrom} for Dy143. Superconducting quantum interference device (SQUID) measurement indicated that neither compound was superconductive down to 5 K. {copyright} {ital 1999 Materials Research Society.}

Zhu, Y.T.; Peterson, E.J.; Baldonado, P.S.; Coulter, J.Y.; Peterson, D.E.; Mueller, F.M. [Mail Stop K763, Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

1999-02-01

148

Densities and thermal expansion of some aqueous rare earth chloride solutions between 5° and 80°C. II. SmClâ, GdClâ, DyClâ, ErClâ, and YbClâ  

Microsoft Academic Search

A dilatometric method is used to determine the densities of aqueous solutions of SmClâ, GdClâ, DyClâ, ErClâ, and YbClâ from approximately 0.1 to 3.5 molal, and from 5 to 80°C at 5° intervals. Temperature and concentration dependent empirical equations representing the apparent molal volumes are given. The partial molal volumes, coefficients of thermal expansion, and apparent and partial molal expansibilities

A. Habenschuss; F. H. Spedding

1976-01-01

149

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

SciTech Connect

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

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

2010-01-15

150

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

PubMed

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

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

2013-08-28

151

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

152

Fabrication and luminescence properties of one-dimensional CaMoO(4): Ln(3+) (Ln = Eu, Tb, Dy) nanofibers via electrospinning process.  

PubMed

One-dimensional CaMoO(4):Ln(3+) (Ln = Eu, Tb, Dy) nanofibers have been prepared by a combination method of sol-gel and electrospinning process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL), and low voltage cathodoluminescence (CL) as well as kinetic decays were used to characterize the resulting samples. SEM and TEM analyses indicate that the obtained precursor fibers have a uniform size, and the as-formed CaMoO(4):Ln(3+) nanofibers consist of nanoparticles. Under ultraviolet excitation, the CaMoO(4) samples exhibit a blue-green emission band with a maximum at 500 nm originating from the MoO(4)(2-) groups. Due to an efficient energy transfer from molybdate groups to dopants, CaMoO(4):Ln(3+) phosphors show their strong characteristic emission under ultraviolet excitation and low-voltage electron beam excitation. The energy transfer process was further studied by the emission spectra and the kinetic decay curves of Ln(3+) upon excitation into the MoO(4)(2-) groups in the CaMoO(4):x mol % Ln(3+) samples (x = 0-5). Furthermore, the emission colors of CaMoO(4):Ln(3+) nanofibers can be tuned from blue-green to green, yellow, and orange-red easily by changing the doping concentrations (x) of Ln(3+) ions, making the materials have potential applications in fluorescent lamps and field emission displays (FEDs). PMID:19583182

Hou, Zhiyao; Chai, Ruitao; Zhang, Milin; Zhang, Cuimiao; Chong, Peng; Xu, Zhenhe; Li, Guogang; Lin, Jun

2009-10-20

153

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

154

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 1325°C to 1530°C for 2 h. The surface morphology of sintered Nd2Zr2O7 was analyzed by scanning electron microscopy. Impedance spectroscopic studies of the samples were carried out at different temperatures. The conductivity increased to the order of 10-2 S/m at 750°C, and the highest conductivity of 13.21 × 10-2 S/m was obtained for Er2Zr2O7. All samples of this system are suitable candidates for fabrication of electrolytes for use in solid oxide fuel cells, particularly at moderate temperatures.

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

2014-10-01

155

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

NASA Astrophysics Data System (ADS)

Lead free magnetoelectric laminates has been prepared by sandwiching Sodium Bismuth Titanate (Na0.5Bi0.5TiO3) between two Tb0.3Dy0.7Fe1.95 (TDF) by epoxy bonding. The piezoelectric material Sodium Bismuth Titanate (Na0.5Bi0.5TiO3) has been prepared by conventional solid state double sintering method and the magnetostrictive material, Tb0.3Dy0.7Fe1.95 (TDF) by vacuum induction melting process. NBT showed a saturated ferroelectric hysteresis behavior with the values of Ps=22.24 ?C/cm2, Ec=41 kV/cm and Pr=27 ?C/cm2. The piezoelectric charge coefficient (d33) measured for NBT was 102 pC/N. Magnetization versus magnetic field measurements were performed in longitudinal (L) and transverse (T) modes of TDF specimen that showed ferromagnetic hysteresis behavior. The magnetostriction of 950 ppm at 4 kOe and static strain coefficient of 0.37×10-6 kOe-1 at 1 kOe magnetic field were recorded for Tb0.3Dy0.7Fe1.95. The magnetoelectric output was measured in L and T modes for the different NBT thickness of 1.0, 1.5 and 2 mm with TDF thickness of 1.5 mm. The high magnetoelectric coefficient (?) was found to be 0.08 mV/cm Oe (L mode) and 0.13 mV/cm Oe (T mode) for the NBT/TDF laminates with 1.0 mm thick NBT.

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

2014-09-01

156

Thermoelectric power and resistivity studies in the Kondo-lattice system CeGa2 with Sn or Al substitutions and RGa2 (R identical to Ho,Dy,Tb) alloys  

Microsoft Academic Search

Resistivity rho and thermopower S studies between 1.7 and 300 K have been carried out to examine Kondo and magnetic ordering effects in Ce(Ga1-xSnx)2, Ce(Ga0.9Al0.1)2 and RGa2 (R identical to Ho,Dy,Tb) alloys. Evidence for the presence of the Kondo effect in CeGa2 was deduced from the high-temperature logarithmic variation observed in the rho data, supporting the conclusions of the earlier

C. S. Garde; J. Ray; G. Chandra

1992-01-01

157

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

PubMed

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

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

2011-01-01

158

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

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

159

Electronic Structure and Nesting-Driven Enhancement of the RKKY Interaction at the Magnetic Ordering Propagation Vector in Gd2PdSi3 and Tb2PdSi3  

Microsoft Academic Search

Measurements of the low-energy electronic structure in Gd2PdSi3 and Tb2PdSi3 by means of angle-resolved photoelectron spectroscopy reveal a Fermi surface consisting of an electron barrel at the Gamma point surrounded by spindle-shaped electron pockets originating from the same band. The calculated momentum-dependent RKKY coupling strength is peaked at the (1)\\/(2)GammaK wave vector, which coincides with the propagation vector of the

D. S. Inosov; D. V. Evtushinsky; A. Koitzsch; V. B. Zabolotnyy; S. V. Borisenko; A. A. Kordyuk; M. Frontzek; M. Loewenhaupt; W. Löser; I. Mazilu; H. Bitterlich; G. Behr; J.-U. Hoffmann; R. Follath; B. Büchner

2009-01-01

160

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

PubMed

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

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

2013-01-28

161

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

162

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 nanoprobe’s optical bioimaging modality available. The possibility of using the nanoprobe for magnetic resonance imaging is also demonstrated, and the nanoprobe displays a clear T1-weighted effect and could potentially serve as a bimodal T1-positive contrast agent. Therefore, the new nanoprobe formed from carbonate nanoprobe doped with rare earth ions provides the dual modality of optical and magnetic resonance imaging.

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

2012-05-01

163

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

PubMed

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

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

2012-08-28

164

Studies of structural, magnetic, electrical and thermal properties in layered perovskite cobaltite SrLnCoO4 (Ln = La, Ce, Pr, Nd, Eu, Gd and Tb)  

NASA Astrophysics Data System (ADS)

The structural, magnetic, electrical and thermal properties have been investigated in single-layered perovskite compounds of SrLnCoO4 (Ln = La, Ce, Pr, Nd, Eu, Gd and Tb) with a K2NiF4-type structure. The variation of Jahn-Teller distortion of the CoO6 octahedron reflected by two different Co-O bond lengths indicates that all the samples are mostly accommodated in the t2g orbital states keeping intermediate spin configuration. The detailed comparison of the temperature dependence of magnetization, resistivity, thermoelectric power and thermal conductivity suggests that the tolerance factor t plays a very crucial role in transport behaviour. With decreasing A-site rare earth ionic radius r_Ln^{3+} , the tolerance factor t decreases and the distortion of the CoO6 octahedron enhances, which results in the increased bending of the Co-O-Co bond, the narrowing of the bandwidth and the decrease in the mobility of eg electrons caused by the substitution of smaller Ln3+ ions for a larger Sr2+ ion.

Ang, R.; Sun, Y. P.; Luo, X.; Hao, C. Y.; Song, W. H.

2008-02-01

165

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

166

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, Rüdiger; Steffen, Andreas; Müller-Buschbaum, Klaus

2014-07-21

167

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

SciTech Connect

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

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

2009-07-15

168

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

PubMed

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

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

2012-04-21

169

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

NASA Astrophysics Data System (ADS)

A first gas electron diffraction study of TbI 3, DyI 3, HoI 3 and ErI 3 has been carried out in combination with mass spectrometric vapour monitoring at 1117(10), 1117(10), 1132(10) and 1102(10) K, respectively. Up to 4 mol.% of dimeric species was observed in addition to the dominating monomeric molecules. The change of the thermal-averaged rg-configuration parameters of the molecules in the series TbI 3 ? ErI 3 reflect the lanthanide contraction. A low value of the shrinkage ?(I…I) even at such a high temperatures may be considered due to vibration effects in molecule whose equilibrium geometric nuclear structure is planar and which correspond to configurationally-averaged 4f n electronic state. B3LYP and ??2 calculations performed in this work with large core potential for lanthanide atoms also resulted in equilibrium geometry of D 3h symmetry. According to the both quantum chemical methods applied the potential function the non-planar vibration is essentially anharmonic, which is therefore to be taken into account to correctly describe nuclear dynamics in molecules such as LnI 3. Different models applied in this study predict the equilibrium distance re(Ln-I) to be shorter than the thermal-averaged rg(Ln-I) distance by 0.002-0.018(1) Å.

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

2010-08-01

170

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

171

Heterometallic tetranuclear [Ln(III)2Co(III)2] complexes including suppression of quantum tunneling of magnetization in the [Dy(III)2Co(III)2] single molecule magnet.  

PubMed

Using a heterometallic approach the synthesis, structures, and magnetic properties are reported for the complexes [Ln(III)(2)Co(III)(2)(OMe)(2)(teaH)(2)(O(2)CPh)(4)(MeOH)(4)](NO(3))(2)·MeOH·H(2)O {Ln = Gd (1a), Tb (2a), and Dy (3a)} and [Ln(III)(2)Co(III)(2)(OMe)(2)(teaH)(2)(O(2)CPh)(4)(MeOH)(2)(NO(3))(2)]·MeOH·H(2)O {Ln = Gd (1b), Tb (2b), and Dy (3b)}. Both compounds for the respective lanthanide ions are found to be isolated within the same crystal. Each Ln(III) dinuclear unit is incorporated within a diamagnetic Co(III)/organic ligand backbone utilizing triethanolamine and benzoic acid as bridging ligands. Magnetic studies reveal an absence of any observable coupling interaction for the Gd case. The Dy analogue displays single molecule magnet (SMM) behavior with a large energy barrier to magnetization reversal of 88.8 K, and the quantum tunneling of the magnetization (QTM) is effectively suppressed because of the nonmagnetic exchange ground state of the molecule. Dilution of the Dy complex into an isostructural diamagnetic yttrium matrix allowed us to determine aspects of the relaxation mechanism within the system. PMID:23072350

Langley, Stuart K; Chilton, Nicholas F; Ungur, Liviu; Moubaraki, Boujemaa; Chibotaru, Liviu F; Murray, Keith S

2012-11-01

172

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

SciTech Connect

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

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

173

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

174

The catalytic activity and surface characterization of Ln 2B 2O 7 (Ln=Sm, Eu, Gd and Tb; B=Ti or Zr) with pyrochlore structure as novel CH 4 combustion catalyst  

Microsoft Academic Search

Ln2B2O7 (Ln=Sm, Eu, Gd and Tb; B=Zr or Ti) with pyrochlore structure was prepared by sol–gel method for the high-temperature catalytic combustion. The crystal structure of Ln2B2O7 was identified by XRD and their surface area was about 4m2\\/g after calcinations at 1200°C. Catalytic activity of methane combustion was observed for Ln2Zr2O7 series and the best catalyst was Sm2Zr2O7. Its relative

Jung Min Sohn; Myoung Rae Kim; Seong Ihl Woo

2003-01-01

175

Heterometallic octanuclear RE(III)3Ni(II)5 (RE = Dy(III), Gd(III) and Y(III)) clusters with slow magnetic relaxation for the dysprosium derivative.  

PubMed

Reactions of rare earth benzoate and nickel perchlorate with a Schiff-base ligand, 2-([(2-hydroxyphenyl)imino]methyl) phenol (H2L), in the presence of triethylamine yielded three heterobimetallic octanuclear clusters of general formula [RE3Ni5L5(PhCOO)3(?3-OH)5(?3-OCH3)(CH3OH)4(H2O)]·xCH3OH·yH2O (RE = Dy(III), x = 4, y = 4 (1), RE = Gd(III), x = 5, y = 4 (2), RE = Y(III), x = 5, y = 3 (3)). Single-crystal X-ray diffraction reveals that the metal core of each cluster consists of two distorted [RE2Ni2O4] cubane-like moieties and a heterobimetallic triangular [RE2NiO2] unit, with RE ions arranged in a typical triangular fashion. Variable-temperature solid state magnetic susceptibilities of these complexes were measured in the temperature range 2-300 K and the results indicate that an overall ferromagnetic interaction among the metal ions is operative for compounds 2 and 3. Under zero external field, the Dy3Ni5 compound shows a frequency dependence of the out-of-phase (?'') signals, which indicates slow relaxation of the magnetization. PMID:23403627

Wang, Huiyu; Ke, Hongshan; Lin, Shuang-Yan; Guo, Yang; Zhao, Lang; Tang, Jinkui; Li, Yun-Hui

2013-04-21

176

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

PubMed

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

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

2012-07-28

177

Correlation between slow magnetic relaxation and the coordination structures of a family of linear trinuclear Zn(II)-Ln(III)-Zn(II) complexes (Ln = Tb, Dy, Ho, Er, Tm and Yb).  

PubMed

Six linear trinuclear [Ln{Zn(L)(AcO)}(2)]BPh(4) complexes (H(2)L denotes the Schiff-base ligand formed by a condensation reaction between ethylenediamine and two equivalents of o-vanillin), including Ln = Tb (1), Dy (2), Ho (3), Er (4), Tm (5) and Yb (6) were synthesized and were confirmed to be isostructural via X-ray crystallographic analyses. The Ln(III) ion in each complex is deca-coordinated by four equatorial oxygen donors from the methoxo groups of the Schiff-base ligands, two oxygen donors from the acetate anions and four axial oxygen donors from the phenoxo groups of the Schiff-base ligands. AC susceptibility measurements, with an oscillating frequency of 10 to 10,000 Hz, revealed that 1, 2, 4 and 6 show slow magnetic relaxation under a 1000 Oe DC bias field, which occurs via a single process, as confirmed by the semi-circular Cole-Cole plots. These complexes are considered to be field-induced single-molecule magnets under these conditions. The presence or absence of the slow magnetic relaxation process is discussed by correlating the characteristic magnetic anisotropy of each Ln(III) ion with the ligand field anisotropy. PMID:22898750

Maeda, Moe; Hino, Shiori; Yamashita, Kei; Kataoka, Yumiko; Nakano, Motohiro; Yamamura, Tomoo; Kajiwara, Takashi

2012-11-28

178

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

179

Syntheses, structures, physical properties, and electronic structures of K Ln2CuS 4 ( Ln=Y, Nd, Sm, Tb, Ho) and K 2Ln4Cu 4S 9 ( Ln=Dy, Ho)  

NASA Astrophysics Data System (ADS)

Seven new quaternary metal sulfides, KY 2CuS 4, KNd 2CuS 4, KSm 2CuS 4, KTb 2CuS 4, KHo 2CuS 4, K 2Dy 4Cu 4S 9, and K 2Ho 4Cu 4S 9, were prepared by the reactive flux method. All crystallographic data were collected at 153 K. The isostructural compounds K Ln2CuS 4 ( Ln=Y, Nd, Sm, Tb, Ho) crystallize in space group Cmcm of the orthorhombic system with four formula units in cells of dimensions ( Ln, a, b, c (Å)): Y, 3.9475(9), 13.345(3), 13.668(3); Nd, 4.0577(3), 13.7442(10), 13.9265(10); Sm, 4.0218(4), 13.6074(14), 13.8264(14); Tb, 3.9679(5), 13.4243(17), 13.7102(18); Ho, 3.9378(3), 13.3330(11), 13.6487(11). The corresponding R1 indices for the refined structures are 0.0197, 0.0153, 0.0158, 0.0181, and 0.0178. The isostructural compounds K 2Dy 4Cu 4S 9 and K 2Ho 4Cu 4S 9 crystallize in space group C2/ m of the monoclinic system with two formula units in cells of dimensions ( Ln, a, b, c (Å), ? (°)): Dy, 13.7061(13), 3.9482(4), 15.8111(15), 109.723(1); Ho, 13.6760(14), 3.9360(4), 15.7950 (16), 109.666(2). The corresponding R1 indices are 0.0312 and 0.0207. Both structure types are closely related three-dimensional tunnel structures. The tunnels are filled with bicapped trigonal-prismatically coordinated K atoms. Their anionic frameworks are built from LnS 6 octahedra and CuS 4 tetrahedra. K Ln2CuS 4 contains ?1[CuS 35-] chains of vertex-sharing tetrahedra and K 2Ln4Cu 4S 9 contains ?1[Cu 4S 812-] chains of tetrahedra. K 2Ho 4Cu 4S 9 shows Curie-Weiss paramagnetic behavior between 5 and 300 K, and has an effective magnetic moment of 10.71 ?B for Ho 3+ at 293 K. Optical band gaps of 2.17 eV for KSm 2CuS 4 and 2.43 eV for K 2Ho 4Cu 4S 9 were deduced from diffuse reflectance spectra. A first-principles calculation of the density of states and the frequency-dependent optical conductivity was performed on KSm 2CuS 4. The calculated band gap of 2.1 eV is in good agreement with the experimental value.

Yao, Jiyong; Deng, Bin; Ellis, Donald E.; Ibers, James A.

2003-11-01

180

Electric-Dipole Active Two-Magnon Excitation in ab Spiral Spin Phase of a Ferroelectric Magnet Gd0.7Tb0.3MnO3  

NASA Astrophysics Data System (ADS)

A broad continuum-like spin excitation (1-10 meV) with a peak structure around 2.4 meV has been observed in the ferroelectric ab spiral spin phase of Gd0.7Tb0.3MnO3 by using terahertz (THz) time-domain spectroscopy. Based on a complete set of light-polarization measurements, we identify the spin excitation active for the light E vector only along the a-axis, which grows in intensity with lowering temperature even from above the magnetic ordering temperature but disappears upon the transition to the A-type antiferromagnetic phase. Such an electric-dipole active spin excitation as observed at THz frequencies can be ascribed to the two-magnon excitation in terms of the unique polarization selection rule in a variety of the magnetically ordered phases.

Kida, Noriaki; Yamasaki, Yuichi; Shimano, Ryo; Arima, Taka-hisa; Tokura, Yoshinori

2008-12-01

181

Magnetic properties of CoFe 1.9RE 0.1O 4 nanoparticles (RE=La, Ce, Nd, Sm, Eu, Gd, Tb, Ho) prepared in polyol  

NASA Astrophysics Data System (ADS)

Highly crystalline CoFe 1.9RE 0.1O 4 ferrite nanoparticles, where RE=La, Ce, Nd, Sm, Eu, Gd, Tb, and Ho, have been synthesized by forced hydrolysis in polyol. X-ray diffraction (XRD), transmission electron microscopy (TEM), electron energy-loss spectroscopy (EELS), 57Fe Mössbauer spectrometry, Co K-edge X-ray absorption spectroscopy and magnetic measurements using a SQUID magnetometer were employed to investigate the effect of the substitution RE 3+ ions for Fe 3+ ones on the structure, the microstructure, the chemical homogeneity, and the magnetic properties of the cobalt ferrite system. All the produced particles are superparamagnetic at room temperature. Nevertheless, the substitution causes reduction of the blocking temperature which is mainly ascribed to partial cation exchange among the spinel-like sublattices of CoFe 2O 4 induced by the insertion of the relatively large RE 3+ ions. The low-temperature saturation magnetization and coercivity appear to be greatly affected by the nature of RE 3+ ions—maxima values were found for Gd 3+ and Eu 3+, respectively.

Tahar, L. Ben; Artus, M.; Ammar, S.; Smiri, L. S.; Herbst, F.; Vaulay, M.-J.; Richard, V.; Grenèche, J.-M.; Villain, F.; Fiévet, F.

182

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

SciTech Connect

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

Alonso, J.A.; Martinez-Lope, M.J.; Casais, M.T.; Arangda, M.A.G.; Fernandez-Diaz, M.T. [C.S.I.C., Madrid (Spain). Inst. de Ciencia de Materiales] [C.S.I.C., Madrid (Spain). Inst. de Ciencia de Materiales; [Univ. de Malaga (Spain). Dept. de Quimica Inorganica, Cristalografia y Mineralogia; [Institut Laue-Langevin, Grenoble (France)

1999-05-26

183

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

184

119Sn Mössbauer spectroscopy of Gd0.8L0.2Mn6Sn6 and Tb0.8L0.2Mn6Sn6 compounds (L=Sc, Y, Lu)  

NASA Astrophysics Data System (ADS)

The HfFe6Ge6-type compounds Gd0.8L0.2Mn6Sn6 and Tb0.8L0.2Mn6Sn6 (L = Sc, Y, Lu) have been studied by 119Sn Mössbauer spectroscopy. The values of the apparent quadrupolar splitting clearly evidence the easy plane magnetization of the gadolinium compounds and the easy axis one in the terbium compounds. The three tin sites behave differently with the nature and size of the substituting L element. For a given series, the hyperfine field of the Sn2d site is almost unchanged whatever the size of the L element. The hyperfine field of the Sn2e site strongly varies with the L size in relation with atomic displacements. The hyperfine field of the Sn2c site exhibits a more complicated behavior. The field difference in the easy plane and easy axis compounds confirms the angle-dependent anisotropic contribution of the Mn moment to the hyperfine field. The analysis of the results also suggests the play of angle-dependent contributions arising from the rare earth moment.

Venturini, G.; Lemoine, P.; Malaman, B.

2012-09-01

185

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

NASA Astrophysics Data System (ADS)

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

2014-07-01

186

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 (4¯2m), is discussed in terms of this model.

Matyjasik, S.; Shaldin, Yu. V.

2013-11-01

187

Magnetoelectric coupling in Tb0.3Dy0.7Fe2/Pt/PbZr0.56Ti0.44O3 thin films deposited on Pt/TiO2/SiO2/Si substrate  

NASA Astrophysics Data System (ADS)

Tb0.3Dy0.7Fe2/Pt/PbZr0.56Ti0.44O3 (Terfenol-D/Pt/PZT) thin films were sputtered on Pt/TiO2/SiO2/Si substrate. PZT and Terfenol-D layers were chosen for their large piezoelectric and magnetostrictive coefficients, respectively. 4%-5% magnetocapacitance has been measured on a Terfenol-D/Pt/PZT stack at room temperature. A magnetoelectric (ME) voltage coefficient of 150 mV/cm Oe was obtained at low dc magnetic field out of mechanical resonance. This work demonstrates the possibility to achieve ME effect in integrated devices involving Terfenol-D and PZT thin films providing that the diffusion, which may occur between both active layers is reduced using an intermediate layer.

Cibert, C.; Zhu, J.; Poullain, G.; Bouregba, R.; More-Chevalier, J.; Pautrat, A.

2013-01-01

188

Magnetothermal study of the hybrid frustrated magnet Dy2-xTbxTi2O7  

Microsoft Academic Search

The two pyrochlore titanates Dy2Ti2O7 and Tb2Ti2O7 have low temperature magnetic states that result from geometrical frustration of the spin-spin interactions between neighboring rare-earth ions. Dy2Ti2O7 is a canonical spin ice material, while the Tb moments in Tb2Ti2O7 have a liquidlike cooperative paramagnetic state at low temperatures. We report magnetic and thermal properties of the hybrid rare-earth titanates, Dy2-xTbxTi2O7 ,

X. Ke; D. V. West; R. J. Cava; P. Schiffer

2009-01-01

189

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

190

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

191

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

SciTech Connect

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

Robin, J. [Institut de Recherches Subatomiques, UMR 7500, IN2P3-CNRS-ULP, F-67037 Strasbourg Cedex 2 (France); LPSC, Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut National Polytechnique de Grenoble, F-38026 Grenoble Cedex (France); Odahara, A. [Institut de Recherches Subatomiques, UMR 7500, IN2P3-CNRS-ULP, F-67037 Strasbourg Cedex 2 (France); Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Duchene, G.; Beck, F. A.; Byrski, Th.; Curien, D.; Courtin, S.; Dorvaux, O.; Gall, B.; Nourredine, A.; Pachoud, E.; Piqueras, I.; Vivien, J. P. [Institut de Recherches Subatomiques, UMR 7500, IN2P3-CNRS-ULP, F-67037 Strasbourg Cedex 2 (France); Twin, P.; Cullen, D. M.; King, S. L.; Paul, E. S. [Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Adimi, N. [USTHB, Institut de Physique, BP32, El Alia, Bab Ezzouar, 16111 Alger (Algeria); Appelbe, D. E.; Simpson, J. [CCLRC, Daresbury Laboratory, Daresbury Warrington WA4 4AD (United Kingdom)] (and others)

2008-09-15

192

Tuberculosis Facts - Exposure to TB  

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193

Tuberculosis Facts - Testing for TB  

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194

Magnetic Properties of Dy in Pb  

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 the previous studies on R=Ce, Pr, Tb, Ho and Er. Specific heat experiments suggest that the Dy ions order antiferromagnetically with an ordering temperature of 1.3K. The magnetic susceptibility data are in good agreement with the susceptibility calculated using crystal field parameters that are extrapolated from previous modeling of the R=Er and Ho analogs of this series.

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

1999-07-10

195

Synthesis and morphology of Ba1-xRE2x/3Nb2O6 nanocrystals with tungsten bronze structure in RE2O3-BaO-Nb2O5-B2O3 glasses (RE: Sm, Eu, Gd, Dy, Er)  

NASA Astrophysics Data System (ADS)

Ba1-xRE2x/3Nb2O6 nanocrystals with a tetragonal tungsten bronze (TTB) structure are synthesized using a conventional glass crystallization technique in 2.3RE2O3-27.4BaO-34.3Nb2O5-36B2O3 (mol%) (RE=Sm, Eu, Gd, Dy, and Er) glasses. One sharp crystallization peak is observed at ?670 °C in both powdered and bulk glasses, and the formation of Ba1-xRE2x/3Nb2O6 nanocrystals with unit cell parameters of a?1.24 nm and c?0.39 nm was confirmed. It is found from high resolution transmission electron microscope observations that the morphology of Ba1-xRE2x/3Nb2O6 nanocrystals is ellipsoidal. Their average particle size is in the range of 15-60 nm and decreases with decreasing ionic radius of RE3+ being present in the precursor glasses. The optical transparent crystallized glass (bulk) shows the total photoluminescence (PL) quantum yield of 53% in the visible region of Eu3+ ions, suggesting a high potential of Ba1-xRE2x/3Nb2O6 nanocrystals as PL materials.

Ida, H.; Shinozaki, K.; Honma, T.; Oh-ishi, K.; Komatsu, T.

2012-12-01

196

Evolution of the Jahn-Teller distortion of MnO6 octahedra in RMnO3 perovskites (R = Pr, Nd, Dy, Tb, Ho, Er, Y): a neutron diffraction study.  

PubMed

Stoichiometric RMnO3 perovskites have been prepared in the widest range of R3+ ionic sizes, from PrMnO3 to ErMnO3. Soft-chemistry procedures have been employed; inert-atmosphere annealings were required to synthesize the materials with more basic R cations (R = Pr, Nd), in order to minimize the unwanted presence of Mn4+. On the contrary, annealings in O2 flow were necessary to stabilize the perovskite phases for the last terms of the series, HoMnO3, ErMnO3, and YMnO3, thus avoiding or minimizing the formation of competitive hexagonal phases with the same stoichiometry. The samples have been investigated at room temperature by high-resolution neutron powder diffraction to follow the evolution of the crystal structures along the series. The results are compared with reported data for LaMnO3. The distortion of the orthorhombic perovskite (space group Pbnm), characterized by the tilting angle of the MnO6 octahedra, progressively increases from Pr to Er due to simple steric factors. Additionally, all of the perovskites show a distortion of the MnO6 octahedra due to the orbital ordering characteristic of the Jahn-Teller effect of Mn3+ cations. The degree of orbital ordering slightly increases from La to Tb and then remains almost unchanged for the last terms of the series. The stability of the crystal structure is also discussed in light of bond-valence arguments. PMID:12526369

Alonso, J A; Martínez-Lope, M J; Casais, M T; Fernández-Dáz, M T

2000-03-01

197

Evolution of the Jahn-Teller distortion of MNO{sub 6} octahedra in RMnO{sub 3} perovskites (R = Pr, Nd, Dy, Tb, Ho, Er, Y): A neutron diffraction study  

SciTech Connect

Stoichiometric RMnO{sub 3} perovskites have been prepared in the widest range of R{sup 3+} ionic sizes, from PrMnO{sub 3} to ErMnO{sub 3}. Soft-chemistry procedures have been employed; inert-atmosphere annealings were required to synthesize the materials with more basic R cations (R = Pr, Nd), in order to minimize the unwanted presence of Mn{sup 4+}. On the contrary, annealings in O{sub 2} flow were necessary to stabilize the perovskite phases for the last terms of the series, HoMnO{sub 3}ErMnO{sub 3}, and YMnO{sub 3}, thus avoiding or minimizing the formation of competitive hexagonal phases with the same stoichiometry. The samples have been investigated at room temperature by high-resolution neutron powder diffraction to follow the evolution of the crystal structures along the series. The results are compared with reported data for LaMnO{sub 3}. The distortion of the orthorhombic perovskite (space group Pbnm), characterized by the tilting angle of the MnO{sub 6} octahedra, progressively increases from Pr to Er due to simple steric factors. Additionally, all of the perovskites show a distortion of the MnO{sub 6} octahedra due to the orbital ordering characteristic of the Jahn-Teller effect of Mn{sup 3+} cations. The degree of orbital ordering slightly increases from La to Tb and then remains almost unchanged for the last terms of the series. The stability of the crystal structure is also discussed in light of bond-valence arguments.

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

2000-03-06

198

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

199

Crystal structure of fluorite-related Ln3SbO7 (Ln=La-Dy) ceramics studied by synchrotron X-ray diffraction and Raman scattering  

NASA Astrophysics Data System (ADS)

Ln3SbO7 (Ln=La, Pr, Nd, Sm, Eu, Gd, Tb and Dy) ceramics were synthesized by solid-state reaction in optimized conditions of temperature and time to yield single-phase ceramics. The crystal structures of the obtained ceramics were investigated by synchrotron X-ray diffraction, second harmonic generation (SHG) and Raman scattering. All samples exhibited fluorite-type orthorhombic structures with different oxygen arrangements as a function of the ionic radius of the lanthanide metal. For ceramics with the largest ionic radii (La-Nd), the ceramics crystallized into the Cmcm space group, while the ceramics with intermediate and smallest ionic radii (Sm-Dy) exhibited a different crystal structure belonging to the same space group, described under the Ccmm setting. The results from SHG and Raman scattering confirmed these settings and ruled out any possibility for the non-centrosymmetric C2221 space group describing the structure of the small ionic radii ceramics, solving a recent controversy in the literature. Besides, the Raman modes for all samples are reported for the first time, showing characteristic features for each group of samples.

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

2013-07-01

200

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

SciTech Connect

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

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

2012-12-15

201

Testing for TB Infection  

MedlinePLUS

... Rapid Molecular Testing to Detect Drug-Resistant TB in the US Executive Summary Introduction Background on Tests for Molecular ... Behavioral & Social Science Research Data & Statistics Reported TB in the US, Surveillance Report Archived Surveillance Reports and Slide Sets ...

202

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.

Tang, Yijun; Baumann, Kristian; Lev, Benjamin L

2014-01-01

203

Tuberculosis Facts - TB and HIV/AIDS  

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... 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 ...

204

Tuberculosis Facts - TB Can Be Treated  

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205

Tuberculosis Facts - You Can Prevent TB  

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... 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 ...

206

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

207

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

208

TB Screening Tests  

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209

Global Tuberculosis (TB)  

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... Peru, Philippines, Russia, Rwanda, South Africa, Thailand, and Vietnam. Learn More » Data and Statistics Reported Tuberculosis in ... Lesotho Mozambique Peru Philippines Rwanda South Africa Thailand Vietnam TB Disease Screening and Diagnosis in People with ...

210

Magnetic and magneto-caloric properties of Tb5Ge2Si2  

Microsoft Academic Search

We have studied the magnetic properties and magneto-caloric effect in the compound Tb5Ge2Si2 by means of magnetic measurements. The compound Tb5Ge2Si2 is a canted antiferromagnet with Gd5Ge2Si2-type monoclinic structure. The ordering temperature is about 76 K. Above the ordering temperature, a field-induced first-order phase transition was observed in the magnetization curves with increasing and decreasing fields. The magnetic entropy changes

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

2002-01-01

211

[Primary structure of subtilisin DY].  

PubMed

The complete amino-acid sequence of subtilisin DY, an extracellular alkaline proteinase produced by Bacillus subtilis, strain DY, is presented. The enzyme's primary structure was elucidated using peptides obtained by tryptic hydrolysis and peptides released from BrCN, tryptophan and Asn-Gly cleavage (using hydroxylamine). The peptides were isolated by gelfiltration and by reversed phase high performance liquid chromatography and were degradated automatically in the sequenator. The complete sequence has been verified by peptide overlapping. The subtilisin DY polypeptide chain, like that of subtilisin Carlsberg, consists of 274 amino-acid residues. 32 Amino-acid replacements were found between these two molecules (37 nucleotide mutations, 5 of them two-point mutations). Between the subtilisins DY and Novo 82 amino-acid residue replacements (106 nucleotide mutations, 24 two-point mutations) and one deletion were found. The polypeptide chains of the three subtilisins mentioned were compared and some differences discussed. PMID:6420308

Nedkov, P; Oberthür, W; Braunitzer, G

1983-11-01

212

Magnetic moments of Gd nuclei  

Microsoft Academic Search

Low temperature nuclear orientation experiments down to 2 mK on147Gd Fe,149Gd Fe,149Gd Gd and153Gd Gd have yielded the magnetic hyperfine interaction strength. Bhf as 31.0(1.6) muNT, 28.3(2.0) muNT, 33.8(4.7) muNT and 13.3(2.1) muNT respectively. From these values the respective ground state magnetic moments ¦mu¦ of147Gd,149Gd and159Gd were deduced as 1.12(20) muN, 1.01(16) muN and 0.40(8) muN.

F. G. van den Berg; W. van Rijswijk; W. R. Joosten; W. J. Huiskamp

1985-01-01

213

Magnetic moments of Gd nuclei  

Microsoft Academic Search

Low temperature nuclear orientation experiments down to 2 mK on147GdFe,149GdFe,149GdGd and153GdGd have yielded the magnetic hyperfine interaction strength. Bhf as 31.0(1.6) ?NT, 28.3(2.0) ?NT, 33.8(4.7) ?NT and 13.3(2.1) ?NT respectively. From these values the respective ground state magnetic moments ¦?¦ of147Gd,149Gd and159Gd were deduced as 1.12(20) ?N, 1.01(16) ?N and 0.40(8) ?N.

F. G. Van Den Berg; W. Van Rijswijk; W. R. Joosten; W. J. Huiskamp

1985-01-01

214

Magnetic properties of Dy2Fe17 and Dy2Fe17C  

Microsoft Academic Search

The magnetic properties of Dy2Fe17 and Dy2Fe17C have been reported. The expansion of the lattice and increase of Curie temperature Tc and magnetization M have been found for Dy2Fe17C, and compared with Dy2Fe17. From the study of 57Fe Mossbauer spectra, we found that the average hyperfine field of Dy2Fe17C is about 5 T larger than that of Dy2Fe17. The isomer

N. Tang; J. Z. Liang; Mingjun Yu; Yi Lu; O. Tegus; Q. A. Li; G. M. Chen; Y. L. Liu; Fu-Ming Yang

1991-01-01

215

Luminescence properties of barium - gadolinium-titanate ceramics doped with rare-earth ions (Eu(3+) and Tb(3+) ).  

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. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24616270

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

2014-11-01

216

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

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

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

2013-06-01

217

Questions and Answers about TB  

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218

Double-layered monopolar order in the Tb2Ti2O7 spin liquid  

NASA Astrophysics Data System (ADS)

Ho2Ti2O7 and Dy2Ti2O7 spin ices exhibit elementary excitations akin to magnetic monopoles. Here, we focus on Tb2Ti2O7 spin liquid, where correlated magnetic moments keep fluctuating down to very low temperatures. Using a monopole picture, we have reanalyzed the field-induced magnetic structure previously determined by neutron diffraction in Tb2Ti2O7. We show that under a high field applied along a [110] direction, Tb2Ti2O7 orders as a three-dimensional arrangement of monopole and antimonopole double layers. In contrast, Ho2Ti2O7 spin ice in the same conditions behaves as a monopole-free state. By symmetry analysis, we derived the distortions compatible with the observed magnetic structure of Tb2Ti2O7, which can be related to the appearance of the double-layered monopolar order.

Sazonov, A. P.; Gukasov, A.; Mirebeau, I.; Bonville, P.

2012-06-01

219

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

220

Magnetostrictive and piezomagnetic properties of Tb1-xDyxZn at low temperatures  

NASA Astrophysics Data System (ADS)

Tb1-xDyxZn(0Tb, Dy, and Sm. The interaction of the oblate 4f electron distribution of Tb and Dy with nearest neighbor ions in these alloys is the source of a huge magnetic anisotropy and high ( 1%) positive magnetostriction. (Alternatively, the prolate shape of the Sm 4f shell gives rise to very large negative magnetostrictions.) Surprisingly, in all measurements to date, the high magnetic anisotropies are independent of crystal structure. Notably, Tb1-xDyx alloys exist in the hexagonal phase, with the c-axis extremely hard, whereas for Tb1-xDyxFe2, a cubic Laves phase alloy, very hard <111> axes can be changed to very hard <100> axes by increasing x from 0 to 1. (In fact, the existence of a near zero magnetic anisotropy by the proper choice of x is the origin of the well-known Terfenol-D alloys, Tb1-xDyxFe2). The Tb$1-x)DyxZn system discussed here is particularly attractive because of the simplicity of its crystal structure (CsCl), its relatively high Curie temperatures (for rare earth alloys), and the existence of a large (uv0) phase for T < 50K. A summary of some of the important properties of these three alloy systems is given in Table I. In all these systems, at least one of the magnetostriction constraints is very large.

Wun-Fogle, Marilyn; Restorff, James B.; Clark, Arthur E.; Cullen, James B.; Lograsso, Thomas A.

2001-07-01

221

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

222

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

223

Anisotropy compensation and spin reorientation in Tb1- xDyx(Fe0.8Co0.2)2  

NASA Astrophysics Data System (ADS)

Structure, magnetic properties, magnetostriction and anisotropy compensation of Tb1- xDyx(Fe0.8Co0.2)2 (0?x?1) have been investigated by means of x-ray diffraction, ac initial susceptibility, SQUID magnetometery, and a standard strain technique. The x-ray diffraction results show that all samples crystallize in a C15 MgCu2-type compound with a Laves phase cubic structure. The lattice parameter as well as the Curie temperature almost linearly decreases with increasing Dy content. The spin reorientation transition occurs at low temperatures when x<0.4, due to the substitution of Co for Fe. The spontaneous magnetostriction ?111 decreases from 2460 ppm for Tb(Fe0.8Co0.2)2 to 1900 ppm for Tb0.4Dy0.6(Fe0.8Co0.2)2. When 0.6Tb-rich side compared with Terfenol-D. The polycrystalline magnetostriction exhibits similar behaviour to that of ?111. The phase diagram for different spin configurations has been given for Tb1- xDyx(Fe0.8Co0.2)2 according to the experimental results.

Guo, Z. J.; Zhang, Z. D.; Wang, B. W.; Zhao, X. G.; Geng, D. Y.; Liu, W.

2001-03-01

224

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

225

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

226

TB in Children in the United States  

MedlinePLUS

... the United States, children account for an estimated 15–20% of TB cases. Global Perspective Related Links Testing for TB Infection ... TB Cases in Specific Groups Pediatric TB Cases Case Completion Slide 1 Slide 2 Slide 3 Slide 4 Slide ... 13 Slide 14 Slide 15 Slide 16 Slide 17 Slide 18 Slide 19 ...

227

Building trust on bovine TB.  

PubMed

Opinion on how best to control bovine TB remains divided, particularly with regard to badgers. Rosie Woodroffe believes that vets have a constructive role to play in the debate and helping farmers locally. PMID:24736823

Woodroffe, Rosie

2014-03-01

228

Gd Transition Probabilities and Abundances  

Microsoft Academic Search

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

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

2006-01-01

229

Magnetic structure of Dy3+ in hexagonal multiferroic DyMnO3  

E-print Network

Magnetic structure of Dy3+ in hexagonal multiferroic DyMnO3 S. Nandi,1,2 A. Kreyssig,1,2 J. Q. Yan structure of the multiferroic compound, hexagonal DyMnO3. In the temperature range from 68 K down to 8 K.075118 PACS number s : 75.25. z, 75.50.Ee, 75.80. q, 77.80. e Magnetoelectric multiferroics

230

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

Microsoft Academic Search

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

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

2004-01-01

231

Treatment: Latent TB Infection (LTBI) and TB Disease  

MedlinePLUS

... Print page ? Listen to audio/Podcast View page in Español (Spanish) Contact Us: Centers for Disease Control and Prevention Division of ... Rapid Molecular Testing to Detect Drug-Resistant TB in the US Executive Summary Introduction Background on Tests for Molecular ...

232

Vibrating-coil magnetometry of the spin liquid properties of Tb2Ti2O7.  

PubMed

We have explored the spin liquid state in Tb(2)Ti(2)O(7) with vibrating-coil magnetometry down to ~0.04 K under magnetic fields up to 5 T. We observe magnetic history dependence below T*~0.2 K reminiscent of the classical spin ice systems Ho(2)Ti(2)O(7) and Dy(2)TiTi(2)O(7). The magnetic phase diagram inferred from the magnetization is essentially isotropic, without evidence of magnetization plateaus as anticipated for so-called quantum spin ice, predicted theoretically for [111] when quantum fluctuations renormalize the interactions. Instead, the magnetization for T?T* agrees semiquantitatively with the predictions of "all-in-all-out" (AIAO) antiferromagnetism. Taken together, this suggests that the spin liquid state in Tb(2)Ti(2)O(7) is akin to an incipient AIAO antiferromagnet. PMID:23006105

Legl, S; Krey, C; Dunsiger, S R; Dabkowska, H A; Rodriguez, J A; Luke, G M; Pfleiderer, C

2012-07-27

233

Vibrating-Coil Magnetometry of the Spin Liquid Properties of Tb2Ti2O7  

NASA Astrophysics Data System (ADS)

We have explored the spin liquid state in Tb2Ti2O7 with vibrating-coil magnetometry down to ˜0.04K under magnetic fields up to 5 T. We observe magnetic history dependence below T*˜0.2K reminiscent of the classical spin ice systems Ho2Ti2O7 and Dy2Ti2O7. The magnetic phase diagram inferred from the magnetization is essentially isotropic, without evidence of magnetization plateaus as anticipated for so-called quantum spin ice, predicted theoretically for [111] when quantum fluctuations renormalize the interactions. Instead, the magnetization for T?T* agrees semiquantitatively with the predictions of “all-in-all-out” (AIAO) antiferromagnetism. Taken together, this suggests that the spin liquid state in Tb2Ti2O7 is akin to an incipient AIAO antiferromagnet.

Legl, S.; Krey, C.; Dunsiger, S. R.; Dabkowska, H. A.; Rodriguez, J. A.; Luke, G. M.; Pfleiderer, C.

2012-07-01

234

Extensively Drug-Resistant Tuberculosis (XDR TB)  

MedlinePLUS

... general symptoms of TB disease include feelings of sickness or weakness, weight loss, fever, and night sweats. ... CDC's Role in Global TB Control Where we work Botswana Cambodia China Guyana Ethiopia Haiti India Kenya ...

235

Study of quasi-continuum gamma-ray deexcitation of 152-161Dy nuclei populated in alpha- and 12C-induced reactions  

Microsoft Academic Search

The influence of the reaction mechanism and of the nuclear structure at high angular momentum on the gamma-ray deexcitation process is studied for Dy nuclei produced in a (40-80 MeV) and 12C (80-110 MeV) induced reactions on 154, 155, 158, 160Gd and 146, 150Nd targets, respectively. The quasi-continuum (q.c.) gamma-ray spectra for selected exit channels are decomposed into collective and

J. Lukasiak; D. C. J. M. Hageman; R. V. F. Janssens; Z. Sujkowski; M. J. A. de Voigt

1982-01-01

236

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

237

Staying on Track with TB Medicine  

MedlinePLUS

Staying on Medicine Track with TB TUBERCULOSIS 2 What’s 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 ...

238

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

Tárkányi, F; Takács, S; Ditrói, F; Csikai, J; Hermanne, A; Ignatyuk, A V

2014-01-01

239

Methionine residue accessibility in native subtilisin DY.  

PubMed

The three methionine residues of subtilisin DY were specifically modified into methionine sulfoxide using increasing amounts of chloramine T. By means of subsequent treatment with cyanogen bromide, gel chromatography, Edman degradation of the obtained peptides and the known structure of subtilisin DY it was established that Met222 is exposed to the surrounding solution, Met124 is partially exposed and Met199 is buried. The data obtained were confirmed on a computer graphics space movable model of subtilisin Carlsberg where Met222 was seen to be on the surface of the molecule and Met199 shielded by Tyr262, Ala179 and Leu196. Upon oxidation of Met222 of subtilisin DY by chloramine T, 25% of its caseinolytic activity was lost. This can be explained by the immediate adjacency to the active-site Ser221. An additional 5% loss of activity was observed at each subsequent methionine modification. PMID:3304336

Lilova, A; Kleinschmidt, T; Nedkov, P

1987-05-01

240

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

241

Treatment and care of TB across Europe  

PubMed Central

There continues to be profound differences in TB incidences as well as in TB treatment and care across Europe in recent years. High TB incidences are observed in Eastern Europe and especially among injecting drug users (IDUs), and there are large overlaps with a HIV epidemic, which is also far from being under control in this region. Further, mortality rates among HIV-positive patients with TB in Eastern Europe were in the 2000s 3–5 fold higher compared with other parts of Europe. As of 2014, there remain many challenges in the organizational set-up of TB care in Eastern Europe and often only limited possibilities of support for the vulnerable IDU populations, including in particular opioid substitution therapy. Further, high prevalences of multi-drug-resistant TB (MR-TB) are an increasing problem in Eastern Europe which in several settings reached beyond 50% among patients previously treated for TB. Obviously, this causes problems for immediate therapy of the individual patients and for development of secondary resistance during therapy. The panel of TB drugs available in TB clinics in Eastern Europe is often limited, and a quick TB diagnosis and acknowledgement of the resistance pattern to guide initial therapy seems to be a priority. For HIV-positive patients in particular, better access to cART may also be an important tool to reduce the TB incidence among these patients. Thus, treatment and care of TB patients in especially Eastern Europe are facing a variety of diagnostic and therapeutic challenges in the coming years. PMID:25394012

Kirk, Ole

2014-01-01

242

The characterisation of treated and dyed hair  

Microsoft Academic Search

Studies have been undertaken to evaluate some of the factors that influence the dyeing of hair with dyes from the Arianor series. Dyed, bleached and untreated hair was examined by differential thermal analysis, optical microscopy, scanning electron microscopy, X-ray diffractometry and surface potential assessment. It has been found that marked changes in surface potentials arise on relatively mild treatment of

J. T. Guthrie; A. Kazlauciunas; L. Rongong; S. Rush

1995-01-01

243

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

244

Magnetic properties of nanomagnetic and biomagnetic systems analyzed using cantilever magnetometry  

E-print Network

and also for the rare earth elements Gd, Dy and Tb at various temperatures. In addition, the magnetic deposited at the free end of a cantilever give rise to a torque on the mechanical sensor, which leads

Aste, Andreas

245

Magnetic phase diagram of Tb 3- xHo xCu 4Sn 4 system  

NASA Astrophysics Data System (ADS)

Magnetic phase diagram of Tb3-xHoxCu4Sn4 was determined on the basis of magnetic and heat capacity data. X-ray diffraction data proved that these compounds crystallize in the orthorhombic Gd3Cu4Ge4-type structure. The compounds are antiferromagnets at low temperatures and the reciprocal magnetic susceptibility obeys the Curie-Weiss law. The paramagnetic Curie temperatures are negative and their absolute values decrease with increasing Ho content. An anomalous concentration dependence of the Néel temperature is observed.

Szytu?a, A.; Jaworska-Go??b, T.; Nenkov, K.; Penc, B.; Zarzycki, A.

2012-03-01

246

Zero field damping capacity in (TbxDy1 - x)Fey  

NASA Astrophysics Data System (ADS)

Materials with a large capacity to dissipate mechanical energy are of interest for passive vibration damping. We have measured the zero-field damping capacity of the giant magnetostrictive terbium-dysprosium-iron compounds by quasistatic stress-strain hysteresis loops. The magnetization and strain of the samples were measured for increasing and decreasing compressive stresses, up to 50 MPa. The zero-field, room temperature damping capacity (?W/W) was calculated from the stress-strain loops and is plotted against maximum stress. The damping capacity maximum for the alloy with the nominal Terfenol-D composition occurs at 4.1 MPa with the value 1.75 which corresponds to Q-1=0.28. The damping is almost independent of stress in a multi-phase sample, (Tb0.6Dy0.4)Fe1.4, which contains both Laves phase and elemental rare earth.

Teter, J. P.; Hathaway, K. B.; Clark, A. E.

1996-04-01

247

Application of GD&T  

NSDL National Science Digital Library

Many students that take a Geometric Dimensioning and Tolerancing (GD&T) course complain that they lack confidence in applying the concepts learned. One reason is not enough opportunities during the course to practice with assemblies instead of the simple parts typically shown in introductory textbooks. The specification of GD&T controls on the skateboard is an exercise that demonstrates that many possible correct solutions exist, depending on the intent of the designer. Only the mating between the skateboard deck and the truck base is studied in detail in this lesson. Other design, manufacturing and assembly issues that can be resolved with the use of GD&T can also be studied and some will be introduced in this ALT.

Castro-Cedeno, Mario H.

2009-12-03

248

Lifetime Measurements in ^160Gd  

NASA Astrophysics Data System (ADS)

The nature of low-lying excitations, K^?=0^+ bands in deformed nuclei remain enigmatic in the field, especially in relationship to quadrupole vibrations. One method of characterizing these states is by reduced transition probabilities, B(E2) values, a measure of the collectivity. These values can be measured directly by Coulomb excitation or calculated from measured lifetime values. Within the deformed region, there are five stable Gd isotopes, three of which have been studied to obtain B(E2) values, a fourth, ^160Gd is the focus of this work. We have examined ^160Gd with the (n,n^'?) reaction and neutron energies up to 3.0 MeV to confirm known 0^+ states and to determine their lifetimes through DSAM measurements. Gamma-ray excitation functions and angular distribution measurements have been performed and preliminary results will be presented.

Lesher, S. R.; Marsh, I.; Aprahamian, A.; Casarella, C.; Smith, M.; Crider, B. P.; Peters, E. E.; Yates, S. W.

2012-10-01

249

Magnetic moments of nuclei around146Gd  

Microsoft Academic Search

Nuclear orientation measurements down to 2.5 mK have been performed on implanted sources of146Eu,147Gd and149Gd in iron. Using a two site model interaction frquencies were deduced from the data. From these, ratios of magnetic moments have been derived as ¦Mu(148Eu)\\/Mu(146Eu)¦=1.90±0.20 and ¦Mu(149Gd)\\/Mu(147Gd)¦=0.86±0.05.

F. G. van den Berg; W. van Rijswijk; W. R. Joosten; W. J. Huiskamp

1983-01-01

250

Magnetic moments of nuclei around 146 Gd  

Microsoft Academic Search

Nuclear orientation measurements down to 2.5 mK have been performed on implanted sources of146Eu,147Gd and149Gd in iron. Using a two site model interaction frquencies were deduced from the data. From these, ratios of magnetic moments have been derived as ¦?(148Eu)\\/?(146Eu)¦=1.90±0.20 and ¦?(149Gd)\\/?(147Gd)¦=0.86±0.05.

F. G. Berg; W. Rijswijk; W. R. Joosten; W. J. Huiskamp

1983-01-01

251

Magnetic properties and microstructure of TbxDy1-xFe2 thin films sputtered on Pt/TiO2/SiO2/Si substrate  

NASA Astrophysics Data System (ADS)

TbxDy1-xFe2 thin films are grown on Pt/TiO2/SiO2/Si substrate by multi-target sputtering. In order to achieve the best magnetic properties, samples grown while heating the sample holder (in situ films) are compared to those prepared at room temperature followed by thermal annealing. The effect of Tb, Dy and Fe content is also examined. It is found that the magnetic properties are very sensitive to the deposition parameters. Magnetization value as high as 680 emu/cm3 with very low coercivity is achieved in a 140 nm thick film whose composition (Tb0.3Dy0.7)Fe2 corresponds to the TERFENOL-D formulation. Observation of soft ferromagnetism and high magnetization are related to crystallization of nano-grains (size 7-10 nm) as deduced from microstructure investigation by X ray diffraction and transmission electron microscopy. It is shown the possibility of growing TERFENOL-D thin films with properties suitable for observation of extrinsic magneto-electric coupling in future thin film devices combining piezoelectric and magnetostrictive materials on metallized silicon substrate.

Zhu, Jiang; Cibert, Christophe; Domenges, Bernadette; Bouregba, Rachid; Poullain, Gilles

2013-05-01

252

Domain pinning and disorder in Fe/Gd magnetic multilayers.  

NASA Astrophysics Data System (ADS)

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

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

2009-03-01

253

Magnetic domain dynamics in Fe/Gd magnetic multilayers  

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

254

HIV-Associated TB in An Giang Province, Vietnam, 2001– 2004: Epidemiology and TB Treatment Outcomes  

E-print Network

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 2001–2004 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 2001–2004, 637 HIV-infected TB patients were diagnosed in An Giang. Of these, 501 (79%) were male, 321 (50%) were aged 25–34 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], 0.3–0.5). Adjusting for male sex, rural residence, TB smear status and

Trinh Thanh Thuy; N. Sarita Shah; Mai Hoang Anh; Do Trong Nghia; Duong Thom; Truong Linh; Dinh Ngoc Sy; Bui Duc Duong; Luu Thi; Minh Chau; Phung Thi; Phuong Mai; Charles D. Wells; Kayla F. Laserson; Jay K. Varma

255

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

256

Dielectric spectroscopy of polyaniline-Dy 2O 3 composites  

NASA Astrophysics Data System (ADS)

Insitu polymerization of aniline was carried out in the presence of dysprosium oxide (Dy 2O 3) to synthesize Polyaniline (PANI)-Dy 2O 3 composites by the chemical oxidation method. The PANI/Dy 2O 3 composites were synthesized with various compositions viz., 10, 20, 30, 40 and 50 wt% of Dy 2O 3 in PANI. AC conductivity was studied in the frequency range 10 2-10 7 Hz. It is observed that AC conductivity achieved its maximum value for 40 wt% of Dy 2O 3 in PANI. The dielectric behavior is also investigated in the frequency range 10 2-10 7 Hz at room temperature. It is found that at 10 KHz frequency the 40 wt% composite shows maximum dielectric values. The dimensions of Dy 2O 3 particles in the matrix have a greater influence on the conductivity values and observed dielectric values.

Sangshetty, K.; Koppalkar, Anilkumar R.; Revansiddappa, M.; Ekhilekar, Shrikant; Ambika Prasad, M. V. N.

2009-07-01

257

Synthesis and Characterization of New Germanate Pyrochlores, A2Ge2O7 (A = Tb, Yb, Er)  

NASA Astrophysics Data System (ADS)

The titanate pyrochlores, A2Ti2O7, have yielded some of the most well-studied geometrically frustrated magnetic materials. A new class of pyrochlores with germanium on the B-site is now being investigated. The germanates, which in many cases share ground states with their titanate analogues, are far more highly correlated due to the smaller B-site cation. Two germanate pyrochlores, Ho2Ge2O7 and Dy2Ge2O7, were previously synthesized and characterized as new spin ice compounds [1-3]. We now present the new germanate pyrochlores, A2Ge2O7 with A = Tb, Yb, and Er. Based on the titanates, three distinctly different magnetic ground states can be expected for these materials: Er2Ti2O7 has an ``order-by-disorder'' mechanism, Yb2Ti2O7 is a quantum spin ice and Tb2Ti2O7 is a spin liquid. Preliminary measurements on Tb2Ge2O7 indicate that it too is a spin liquid down to at least 0.35 K. We will present the characterizations of A2Ge2O7 (A = Tb, Yb, Er) and compare them to the titanates.[4pt] [1] H. D. Zhou et al., Nature Communications 2, 478 (2011). [0pt] [2] H. D. Zhou et al., Phys. Rev. Lett. 108, 207206 (2012).[0pt] [3] A. M. Hallas et al., accepted for publication in Phys. Rev. B (2012).

Hallas, Alannah; Zhou, Haidong; Arevalo Lopez, Angel; Silverstein, Harlyn; Attfield, J. Paul; Wiebe, Christopher

2013-03-01

258

Ultraviolet-induced thermoluminescence and phosphorescence in Mg2SiO4:Tb.  

PubMed

Among the common TLD materials studied (Mg2SiO4:Tb, Al2O3:Si, Ti, CaSO4:Tm, CaSO4:Dy, Li2B4O7:Mn and LiF TLD-100), Mg2SiO4:Tb was found to have the highest intrinsic TL sensitivity to UV radiation (wavelength 253.7 nm). The TL response of the dosimetric peak (approximately 200 degrees C) of virgin Mg2SiO4:Tb was studied as a function of UV exposure in the range 10--10(4) J m-2. The UV-induced TL was not affected by room-light and no appreciable fading was observed up to 20 days after irradiation indicating that this is a promising TL phosphor for UV dosimetry. The UV sensitivity was found to increase with increasing preliminary gamma exposure above 10(-2)Ckg-1 (after a post-irradiation anneal at 300 degrees C for 1 h). The degree of sensitisation was found proportional to the intensity of the residual TL peak at 450 degrees C. A study of the TL response of the sensitised sample as a function of UV test exposure has demonstrated the transfer of charge carriers from the deep traps to the dosimetry traps. Both virgin and gamma-exposed Mg2SiO4:Tb were found to exhigit phosphorescence decay at room temperature after UV stimulation. The intensity of the UV stimulated phosphorescence was found to increase with the gamma exposure above 10(-2) C kg-1. PMID:213794

Lakshmanan, A R; Shinde, S S; Bhatt, R C

1978-09-01

259

Effects of Dy 2BaCuO 5 contents on microstructure and mechanical strength of Ag-added Dy–Ba–Cu–O bulk superconductors  

Microsoft Academic Search

We investigated the microstructure and mechanical strength of Ag-added DyBa2Cu3Oy (Dy123) bulk superconductors with various Dy2BaCuO5 (Dy211) contents. Single-grain Dy123 bulk samples 32 mm in diameter with the addition of 5-40 mol% of Dy211 and 10 wt.% of Ag2O were fabricated in air. The sample with 5 mol% Dy211 contained many macro-cracks in the ab-plane. The amount of cracks decreased

S. Nariki; N. Sakai; M. Murakami; I. Hirabayashi

2004-01-01

260

Magnetic domain pinning in an anisotropy-engineered GdTbFe thin film  

SciTech Connect

Focused ion beam irradiation was used to reduce locally the perpendicular anisotropy of magnetic thin films in rectangular lattices of 50 nm sized dots. The effect of the anisotropy patterns, differing in ion fluence and interdot spacing, on the magnetization reversal process was determined in q space with x-ray resonant magnetic scattering and in real space with magnetic force microscopy. At remanence only a slight alignment of the irregularly shaped domains is observed. In perpendicular magnetic fields, however, the high field bubble domains display a pronounced localization on the dots, showing that this form of local anisotropy reduction is a highly efficient way of domain positioning.

Konings, Stan; Miguel, Jorge; Goedkoop, Jeroen; Camarero, Julio; Vogel, Jan [Van der Waals-Zeeman Institute, University of Amsterdam, Valckenierstraat 65, 1018 XE Amsterdam (Netherlands); Departamento de Fisica de la Materia Condensada, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Laboratoire Louis Neel, CNRS, BP 166, F-38042 Grenoble (France)

2006-08-01

261

HIV/STD/TB PREVENTION NEWS DATABASE  

EPA Science Inventory

The CDC National Prevention Information Network (NPIN) is the U.S. reference, referral, and distribution service for information on HIV/AIDS, sexually transmitted diseases (STDs), and tuberculosis (TB). NPIN produces, collects, catalogs, processes, stocks, and disseminates materi...

262

Co-Fe-Gd (Cobalt-Iron-Gadolinium)  

Microsoft Academic Search

mal sections that agree reasonably well with the limited experimental results available. The isothermal section at 1050 8C determined by [1990Ati] (reviewed in [1992Rag]) shows that the pairs Fe17Gd2-Co17Gd2 ,F e 3Gd-Co3Gd, and Fe2Gd-Co2Gd form Binary Systems continuous solid solutions. These solutions are denoted here by M17Gd2 ,M 3Gd, and M2Gd, respectively. [1995Liu] evaluated the thermodynamic properties of this ternary

V. Raghavan; Ternary Isothermal Sections

2001-01-01

263

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

264

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

265

Thermomagnetic properties of GdPd  

SciTech Connect

The magnetic susceptibility, magnetization, and field-dependent heat capacity of ferromagnetic GdPd have been measured. The magnetic moment of the Gd spin obtained from the saturation magnetization at 4.2/sup 0/K is enhanced over the free Gd value. The heat capacity shows a large lambda-type magnetic anomaly at the Curie temperature of 40.0 + 0.5/sup 0/K.

Barclay, J.A.; Overton, W.C. Jr.; Zimm, C.B.

1984-01-01

266

Assessing the impact of TB/HIV services integration on TB treatment outcomes and their relevance in TB/HIV monitoring in Ghana  

PubMed Central

Background The impact of the human immunodeficiency virus (HIV) on tuberculosis (TB), and the implications for TB and HIV control, is a public health challenge in Ghana – almost a quarter (23%) of all TB cases were HIV positive in 2010. The integration of TB/HIV services has therefore emerged as an essential component of the national response to TB and HIV. The aim is to reduce fragmentation, improve access, enhance efficiency and improve quality of care. Ghana’s TB/HIV policy comprises three linked sets of activities: effective implementation of the Stop TB Strategy for TB control, improved HIV prevention and care, and the implementation of additional TB/HIV activities. Different models of service delivery with increasing integration of TB/HIV activities are expected to provide greater access to more comprehensive care. The objective of this paper is to assess the impact of TB/HIV integration on TB treatment outcomes and to explore the usefulness of TB treatment outcomes as TB/HIV indicators. Methods A before-and-after study to observe the introduction of TB/HIV activities into TB programmes in three hospitals with different levels of integration was conducted. Anonymised patient data was collated from TB registers from each facility, and analysed to determine if TB treatment outcomes changed significantly after integration. Results TB treatment success was 50% (95% CI 49 – 52) prior to, and 69% (95% CI 65 – 73) after, integration (?2 43.96, p < 0.00). Treatment success increased from 43% to 53% at the one-stop shop (OSS), from 69% to 78% at the partially integrated site (PIS) and substantially from 46% to 78% at the referral site (RS) (?2 64.54; p<0.01). Defaults and cases transferred out reduced from 14.3% and 15.3% prior to integration, to 1.4% and 9.0% after integration, respectively, accounting for a significant increase in treatment success. Death rates remained high at 18% in all cases studied and 25% in HIV-associated cases after integration. Conclusion TB/HIV integration may improve TB treatment success, but its exact impact is difficult to ascertain due to non-specificity and design limitations. TB mortality may be more useful as an indicator for monitoring TB/HIV activities in Ghana. PMID:23849044

2012-01-01

267

Decay properties of long-lived isomers in the odd-odd N=81 nucleus Tb146 compared to the Ho148 and Tm150 nuclei  

NASA Astrophysics Data System (ADS)

Excited states of the Tb146 nucleus have been studied using ?-ray and electron spectroscopy in off-beam and in-beam modes following Sn112(Ar40,3n3p) reaction with the use of the OSIRIS-II, HPGe detector array and the conversion electron spectrometer. The multipolarity of the 343 keV transition deexciting the (7-) level in Tb146 shows mainly an E2 nature and the first excited state above the 23 s isomer is assigned as a (5-,6-) state. The log ft values have been deduced for 11 ?+/EC transitions populating excited states in Gd146. The systematic behavior of spins and parities of the long-lived levels at 0+x keV and the first excited states above them in the N=81 isotones Tb146, Ho148, and Tm150 is discussed.

Kownacki, J.; Droste, Ch.; Morek, T.; Ruchowska, E.; Lieder, R. M.; Kisieli?ski, M.; Kowalczyk, M.; Andrzejewski, J.; Perkowski, J.; Napiorkowski, P. J.; Wrzosek-Lipska, K.; Zieli?ska, M.; Kordyasz, A.; Korman, A.; Hady?ska-Kl?k, K.; Grodner, E.; Mierzejewski, J.; Srebrny, J.

2011-02-01

268

Effects of DyHx and Dy2O3 powder addition on magnetic and microstructural properties of Nd-Fe-B sintered magnets  

NASA Astrophysics Data System (ADS)

The magnetic and microstructural properties of (Nd27.68Dy4.89)-Febal.B1.0M2.4 (wt. %, M = Cu, Al, Co, and Nb) sintered magnets doped with Dy2O3 and DyHx powders were studied. The coercivity of the DyHx-doped magnet improved, with no change in the remanence. Well-developed core-shell microstructures were seen in the DyHx-doped magnet, as compared to the case of the Dy2O3-doped magnet. Diffusion of Dy was enhanced in the DyHx-doped magnet, probably because dissolution of hydrogen in Nd2Fe14B increased the lattice parameter. The (00L) grain alignment in the DyHx-doped magnet was also improved.

Bae, Kyoung-Hoon; Kim, Tae-Hoon; Lee, Seong-Rae; Namkung, Seok; Jang, Tae-Suk

2012-11-01

269

Long range ordered magnetic and atomic structures of the quasicrystal approximant in the Tb-Au-Si system.  

PubMed

The atomic and magnetic structure of the 1/1 Tb(14)Au(70)Si(16) quasicrystal approximant has been solved by combining x-ray and neutron diffraction data. The atomic structure is classified as a Tsai-type 1/1 approximant with certain structural deviations from the prototype structures; there are additional atomic positions in the so-called cubic interstices as well as in the cluster centers. The magnetic property and neutron diffraction measurements indicate the magnetic structure to be ferrimagnetic-like below 9 K in contrast to the related Gd(14)Au(70)Si(16) structure that is reported to be purely ferromagnetic. PMID:25055216

Gebresenbut, Girma; Andersson, Mikael Svante; Beran, P?emysl; Manuel, Pascal; Nordblad, Per; Sahlberg, Martin; Gomez, Cesar Pay

2014-08-13

270

Long range ordered magnetic and atomic structures of the quasicrystal approximant in the Tb-Au-Si system  

NASA Astrophysics Data System (ADS)

The atomic and magnetic structure of the 1/1 Tb(14)Au(70)Si(16) quasicrystal approximant has been solved by combining x-ray and neutron diffraction data. The atomic structure is classified as a Tsai-type 1/1 approximant with certain structural deviations from the prototype structures; there are additional atomic positions in the so-called cubic interstices as well as in the cluster centers. The magnetic property and neutron diffraction measurements indicate the magnetic structure to be ferrimagnetic-like below 9 K in contrast to the related Gd(14)Au(70)Si(16) structure that is reported to be purely ferromagnetic.

Gebresenbut, Girma; Svante Andersson, Mikael; Beran, P?emysl; Manuel, Pascal; Nordblad, Per; Sahlberg, Martin; Pay Gomez, Cesar

2014-08-01

271

An evaluation of UV protection imparted by cotton fabrics dyed with natural colorants  

Microsoft Academic Search

BACKGROUND: The ultraviolet properties of textiles dyed with synthetic dyes have been widely reported in literature. However, no study has investigated the ultraviolet properties of natural fabrics dyed with natural colorants. This study reports the Ultraviolet Protection Factor (UPF) of cotton fabrics dyed with colorants of plant and insect origins. METHODS: Three cotton fabrics were dyed with three natural colorants.

Ajoy K Sarkar

2004-01-01

272

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

SciTech Connect

Single crystals of a new sodium ytterbium oxalate Na[Yb(C{sub 2}O{sub 4}){sub 2}(H{sub 2}O)].3H{sub 2}O (1) and six mixed lanthanide (III)-uranium (IV) oxalates (NH{sub 4}{sup +}){sub 1-x}[Ln{sub 1-x}U{sub x} (C{sub 2}O{sub 4}){sub 2}(H{sub 2}O)].(3+x) H{sub 2}O, 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)A, b=8.564(2)A, c=14.938(3)A, {beta}=103.062(3), Z=4. The structure of 1 is isotypic with Na[Y(C{sub 2}O{sub 4}){sub 2}(H{sub 2}O)].3H{sub 2}O 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{sup +} 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)A 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-coorted 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. [Laboratoire de Cristallochimie et Physicochimie du Solide, UMR CNRS 8012, ENSCL-USTL, B.P. 90108, 59652 Villeneuve d'Ascq Cedex (France); Laboratoire de Chimie des Actinides, CEA VALRHO/DRCP/SCPS, Bat 399 BP 17171, 30208 Bagnols sur Ceze Cedex (France); Duvieubourg, L. [Laboratoire de Cristallochimie et Physicochimie du Solide, UMR CNRS 8012, ENSCL-USTL, B.P. 90108, 59652 Villeneuve d'Ascq Cedex (France); Nowogrocki, G. [Laboratoire de Cristallochimie et Physicochimie du Solide, UMR CNRS 8012, ENSCL-USTL, B.P. 90108, 59652 Villeneuve d'Ascq Cedex (France); Abraham, F. [Laboratoire de Cristallochimie et Physicochimie du Solide, UMR CNRS 8012, ENSCL-USTL, B.P. 90108, 59652 Villeneuve d'Ascq Cedex (France)]. E-mail: francis.abraham@ensc-lille.fr; Grandjean, S. [Laboratoire de Chimie des Actinides, CEA VALRHO/DRCP/SCPS, Bat 399 BP 17171, 30208 Bagnols sur Ceze Cedex (France)

2006-12-15

273

High throughput crystallography of TB drug targets.  

PubMed

Tuberculosis (TB) infects one-third of the world population. Despite 50 years of available drug treatments, TB continues to increase at a significant rate. The failure to control TB stems in part from the expense of delivering treatment to infected individuals and from complex treatment regimens. Incomplete treatment has fueled the emergence of multi-drug resistant (MDR) strains of Mycobacterium tuberculosis (Mtb). Reducing non-compliance by reducing the duration of chemotherapy will have a great impact on TB control. The development of new drugs that either kill persisting organisms, inhibit bacilli from entering the persistent phase, or convert the persistent bacilli into actively growing cells susceptible to our current drugs will have a positive effect. We are taking a multidisciplinary approach that will identify and characterize new drug targets that are essential for persistent Mtb. Targets are exposed to a battery of analyses including microarray experiments, bioinformatics, and genetic techniques to prioritize potential drug targets from Mtb for structural analysis. Our core structural genomics pipeline works with the individual laboratories to produce diffraction quality crystals of targeted proteins, and structural analysis will be completed by the individual laboratories. We also have capabilities for functional analysis and the virtual ligand screening to identify novel inhibitors for target validation. Our overarching goals are to increase the knowledge of Mtb pathogenesis using the TB research community to drive structural genomics, particularly related to persistence, develop a central repository for TB research reagents, and discover chemical inhibitors of drug targets for future development of lead compounds. PMID:17970224

Murillo, A C; Li, H Y; Alber, T; Baker, E N; Berger, J M; Cherney, L T; Cherney, M M; Cho, Yoon Song; Eisenberg, D; Garen, C R; Goulding, C W; Hung, L W; Ioerger, T R; Jacobs, W R; James, M N G; Kim, C; Krieger, I; Lott, J S; Sankaranarayanan, R; Segelke, B W; Terwilliger, T C; Wang, F; Wang, S; Sacchettini, J C

2007-06-01

274

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

275

Hetero-tri-spin [2p-3d-4f] Chain Compounds Based on Nitronyl Nitroxide Lanthanide Metallo-Ligands: Synthesis, Structure, and Magnetic Properties.  

PubMed

Employing nitronyl nitroxide lanthanide(III) complexes as metallo-ligands allowed the efficient and highly selective preparation of three series of unprecedented hetero-tri-spin (Cu?Ln-radical) one-dimensional compounds. These 2p-3d-4f spin systems, namely [Ln3 Cu(hfac)11 (NitPhOAll)4 ] (Ln(III) =Gd 1Gd , Tb 1Tb , Dy 1Dy ; NitPhOAll=2-(4'-allyloxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide), [Ln3 Cu(hfac)11 (NitPhOPr)4 ] (Ln(III) =Gd 2Gd , Tb 2Tb , Dy 2Dy , Ho 2Ho , Yb 2Yb ; NitPhOPr=2-(4'-propoxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) and [Ln3 Cu(hfac)11 (NitPhOBz)4 ] (Ln(III) =Gd 3Gd , Tb 3Tb , Dy 3Dy ; NitPhOBz=2-(4'-benzyloxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) involve O-bound nitronyl nitroxide radicals as bridging ligands in chain structures with a [Cu-Nit-Ln-Nit-Ln-Nit-Ln-Nit] repeating unit. The dc magnetic studies show that ferromagnetic metal-radical interactions take place in these hetero-tri-spin chain complexes, these and the next-neighbor interactions have been quantified for the Gd derivatives. Complexes 1Tb and 2Tb exhibit frequency dependence of ac magnetic susceptibilities, indicating single-chain magnet behavior. PMID:25169024

Zhu, Mei; Hu, Peng; Li, Yungai; Wang, Xiufeng; Li, Licun; Liao, Daizheng; Durga Prasad Goli, V M L; Ramasesha, S; Sutter, Jean-Pascal

2014-10-01

276

If I Had - Recurring Cough and Positive TB Test  

MedlinePLUS Videos and Cool Tools

... If I Had - Recurring Cough and Positive TB Test - Dr. Masae Kawamura, MD, University of California, San ... If I Had - Recurring Cough and Positive TB Test - Dr. Masae Kawamura, MD, University of California, San ...

277

TB in the United States: A Snapshot, 2013  

MedlinePLUS

... foreign-born TB patients originated from five countries (Mexico, the Philippines, India, Vietnam, and China). MDR TB ... Severe Impact among Other Populations Individuals living with HIV: People living with HIV are at high risk ...

278

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

MedlinePLUS

... Rapid Molecular Testing to Detect Drug-Resistant TB in the US Executive Summary Introduction Background on Tests for Molecular ... Behavioral & Social Science Research Data & Statistics Reported TB in the US, Surveillance Report Archived Surveillance Reports and Slide Sets ...

279

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

Microsoft Academic Search

Multiple myeloma and other hematological malignancies have been treated by myeloablative radiotherapy\\/chemotherapy and subsequent stem cell transplantation. [166Dy]Dy\\/166Ho-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)

Martha Pedraza-López; Guillermina Ferro-Flores; Consuelo Arteaga de Murphy; Pedro Morales-Ramírez; Josefa Piedras-Ross; Eduardo Murphy-Stack; Omar Hernández-Oviedo

2004-01-01

280

Effect of Dy/Nd double layer on coercivity in Nd-Fe-B thin films  

NASA Astrophysics Data System (ADS)

The Nd-Fe-B (tNFB = 30 nm)/[Dy (tDy nm)/Nd (tNd nm)] (tDy/Nd = 20 nm) (thickness tDy = 0-10 nm) thin films were deposited on Al2O3(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 tDy = 10 nm and tNd = 10 nm becomes large due to the Dy and the Nd atoms thermal diffusion, while DyFe2 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 Hc of Nd-Fe-B/Dy/Nd thin films with the tDy = 10 nm and tNd = 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, Hc is enhanced to be about 22.1 kOe in the annealed Nd-Fe-B/Dy/Nd films with the tDy = 0.8 nm and tNd = 19.2 nm.

Koike, K.; Umezawa, J.; Ishikawa, H.; Ogawa, D.; Mizuno, Y.; Kato, H.; Miyazaki, T.; Ando, Y.

2014-05-01

281

pH-induced Dy4 and Dy10 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 () and {[Dy10(?3-OH)8(L)22(bipy)2(H2O)2]·5H2O}n () (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 and were established by the single crystal X-ray diffraction technique, and both of them exhibit complicated 1D chains with [Dy4] () and [Dy10] () cluster units, respectively. Adjacent [Dy4] in and [Dy10] in 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 and 3.2 K for . Interestingly, the large divergence in both the structures and magnetic properties for and 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

2014-10-22

282

Temperature Sensing Above 1000 C Using Cr-Doped GdAlO3 Spin-Allowed Broadband Luminescence  

NASA Technical Reports Server (NTRS)

Cr-doped GdAlO3 (Cr:GdAlO3) is shown to produce remarkably high-intensity spin-allowed broadband luminescence with sufficiently long decay times to make effective luminescence-decay-time based temperature measurements above 1000 C. This phosphor is therefore an attractive alternative to the much lower luminescence intensity rare-earth-doped thermographic phosphors that are typically utilized at these elevated temperatures. In particular, Cr:GdAlO3 will be preferred over rare-earth-doped phosphors, such as Dy:YAG, at temperatures up to 1200 C for intensity-starved situations when the much lower emission intensity from rare-earth-doped phosphors is insufficient for accurate temperature measurements in the presence of significant radiation background. While transition-metal-doped phosphors such as Cr:Al2O3 (ruby) are known to exhibit high luminescence intensity at low dopant concentrations, quenching due to nonradiative decay pathways competing with the (sup 2)E to (sup 4)A(sub 2) radiative transition (R line) has typically restricted their use for temperature sensing to below 600 C. Thermal quenching of the broadband (sup 4)T(sub 2) to (sup 4)A(sub 2) radiative transition from Cr:GdAlO3, however, is delayed until much higher temperatures (above 1000 C). This spin-allowed broadband emission persists to high temperatures because the lower-lying (sup 2)E energy level acts as a reservoir to thermally populate the higher shorter-lived (sup 4)T(sub 2) energy level and because the activation energy for nonradiative crossover relaxation from the (sup 4)T(sub 2) level to the (sup 4)A(sub 2) ground state is high. The strong crystal field associated with the tight bonding of the AlO6 octahedra in the GdAlO3 perovskite structure is responsible for this behavior.

Eldridge, Jeffrey I.; Chambers, Matthew D.

2012-01-01

283

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 20 nm. 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. Brück; D. Y. Geng; Z. D. Zhang

2008-01-01

284

Hydrides of DyCo/sub 3/  

SciTech Connect

Hydrogen desorption isotherms have been measured in the system DyCo/sub 3/H/sub x/ for 0 less than or equal to x less than or equal to 4.25 at temperatures of 0/sup 0/, 20/sup 0/, 40/sup 0/, 60/sup 0/, and 80/sup 0/C. Pressure plateaus on the isotherms indicate the existence of two hydride phases in addition to the terminal hydrogen-saturated metal ..cap alpha.. phase. Both exhibit a wide range of solid solutions. The ..beta.. phase runs from x = 1 to x = 1.83, while the ..gamma.. phase runs from 3.1 to at least 4.25. The ..cap alpha.. phase is very narrow. At 20/sup 0/C the plateau pressures are 3 torr and 54 torr, and the heats of absorption are -11.43 and -9.75 kcal/mole(H/sub 2/) respectively. From the temperature dependence of the isotherms, the partial molar heats and entropies of absorption and the heats and entropies of formation have been calculated as a function of x.

Kierstead, H.A.

1980-01-01

285

The phase diagram YF-GdF  

Microsoft Academic Search

The binary phase diagram YF-GdF was studied by differential scanning calorimetry (DSC). Yttrium fluoride and gadolinium fluoride show complete miscibility in all three phases (orthorhombic room temperature phase, trigonal or hexagonal high temperature phase, liquid). The transformations between room temperature and high temperature phases are of first order and occur at 1338.6 K (YF) or 1174.8 K (GdF). Melting points

D. Klimm; I. M. Ranieri; R. Bertram; S. L. Baldochi

2008-01-01

286

GAPS IN THE GD-1 STAR STREAM  

SciTech Connect

GD-1 is a long, thin, Milky Way star stream that has readily visible density variations along its length. We quantify the locations, sizes, and statistical significance of the density structure, i.e., gaps, using a set of scaled filters. The shapes of the filters are based on the gaps that develop in simulations of dark matter sub-halos crossing a star stream. The high Galactic latitude 8.4 kpc long segment of GD-1 that we examine has 8 {+-} 3 gaps of 99% significance or greater, with the error estimated on the basis of tests of the gap-filtering technique. The cumulative distribution of gaps more than three times the width of the stream is in good agreement with predictions for dark matter sub-halo encounters with cold star streams. The number of gaps narrower than three times the width of the GD-1 stream falls well below the cold stream prediction which is taken into account for the gap creation rate integrated over all sizes. Simple warm stream simulations scaled to GD-1 show that the falloff in gaps is expected for sub-halos below a mass of 10{sup 6} M{sub Sun }. The GD-1 gaps requires 100 sub-halos >10{sup 6} M{sub Sun} within 30 kpc, the apocenter of GD-1 orbit. These results are consistent with LCDM sub-halo predictions but further improvements in stream signal-to-noise and gap modeling will be welcome.

Carlberg, R. G. [Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H4 (Canada); Grillmair, C. J., E-mail: carlberg@astro.utoronto.ca, E-mail: carl@ipac.caltech.edu [Spitzer Science Center, 1200 East California Boulevard, Pasadena, CA 91125 (United States)

2013-05-10

287

Magnetoresistance of Gd doped Carbon films  

NASA Astrophysics Data System (ADS)

The rare earth dopant Gd was introduced into amorphous carbon (a-C) by two quite different techniques; mass selected ion beam deposition (MSIBD) of tetrahedral amorphous carbon (ta-C) followed by Gd implantation and magnetron co-sputtering of Gd and C targets. Raman, RBS and TEM characterization indicate the films are metastable. Films prepared by sputtering (a-GdxC1-x x=4.2 ˜15.6 at.%) have a spin-glass freezing with a temperature which (2-6K) scales with Gd concentration. Films prepared by MSIBD followed by ion implantation (taC:Gdx, x=4, 7, 13 at.%) show no freezing and a paramagnetic Curie-Weiss law down to 1.9K. Transport measurements show typical doped amorphous semiconductor behavior with very large negative magnetoresistance (MR). The MR of the two types of films are similar, which indicates a universal magnetic moment-carrier interaction in these Gd doped amorphous semiconductor systems. A comparison of these films' MR with other Gd doped semiconductors such as a-GdxSi and a-GdxGe will be discussed. The MR properties of this type of thin film material indicate the importance of the local materials structure and the consequence of the electron screening effects.

Helgren, Erik; Zeng, Li; Ronning, C.; Zutz, H.; Ager, J.; Hellman, F.

2007-03-01

288

Structural evolution and fluorescence properties of Dy3+: silica matrix  

NASA Astrophysics Data System (ADS)

The Dy3+ doped silica glasses were prepared by sol-gel process with appropriate heat treatment. The structural changes during the gel to glass transition of the silica xerogels and the effect on fluorescence properties of Dy3+ were studied. For Dy3+ two dominant emissions occur at about 575nm(4F9/2-->6H15/2) in the yellow region and 480nm (4F9/2-->6H13/2) in the blue region. Both transitions are electric dipole in nature out of which (4F9/2-->6H13/2) is hypersensitive. The intensity ratio (yellow to blue (Y/B)) of Dy3+ emission follows a trend parallel to the red to orange (R/O) ratio of Eu3+ in silica matrices. These ratios are influenced by the site symmetry and electro negativity of ligand atoms. The fluorescence intensity of Dy3+ ions increases remarkably when the doped xerogel is heat-treated. The fluorescence intensity ratio (Y/B) is used as a measure of the symmetry of Dy3+ environment during the gel - glass conversion, the higher the ratio, the more asymmetric is the environment. The high value of the intensity ratio of the 1000°C heated gel showed that the Dy3+ was embedded in the glassy silica network with an asymmetric environment. The FTIR and thermo gravimetric analysis (TGA) clearly showed the complete densification (density=2.2 gm/cm3) of the gels around 1000°C.

Unnikrishnan, N. V.; Thomas, Vinoy; Jose, Gijo; Jose, Gin

2002-08-01

289

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-López, Martha; Ferro-Flores, Guillermina; Arteaga de Murphy, Consuelo; Morales-Ramírez, Pedro; Piedras-Ross, Josefa; Murphy-Stack, Eduardo; Hernández-Oviedo, Omar

2004-11-01

290

Inverse effect of morphotropic phase boundary on the magnetostriction of ferromagnetic Tb1-xGdxCo2  

NASA Astrophysics Data System (ADS)

The morphotropic phase boundary (MPB) has been utilized extensively in ferroelectrics and recently has attracted interest in ferromagnets [S. Yang, H. Bao, C. Zhou, Y. Wang, X. Ren, Y. Matsushita, Y. Katsuya, M. Tanaka, K. Kobayashi, X. Song, and J. Gao, Phys. Rev. Lett. 104, 197201 (2010), 10.1103/PhysRevLett.104.197201; R. Bergstrom, M. Wuttig, J. Cullen, P. Zavalij, R. Briber, C. Dennis, V. O. Garlea, and M. Laver, Phys. Rev. Lett. 111, 017203 (2013), 10.1103/PhysRevLett.111.017203] for obtaining enhanced large field-induced strain. Here we report that the MPB can also lead to weakening (the inverse effect as compared to the known MPB materials) of field-induced strain, as exhibited in the Tb1-xGdxCo2 system. With synchrotron x-ray diffractometry, the structure symmetry of TbCo2-rich compositions is detected to be rhombohedral below TC and that of GdCo2-rich compositions is tetragonal. The MPB composition Tb0.1Gd0.9Co2, corresponding to the two phases (rhombohedral and tetragonal) of coexistence, shows the exotic minimum (near zero) magnetostriction as well as the largest magnetic susceptibility among all samples. Further analysis suggests that whether MPB can enhance or weaken magnetostriction is determined by the degree of magnetic ordering of two end members that form ferromagnetic MPBs, which was not considered previously. Our work not only reveals a new type of ferromagnetic MPB, but also provides a new recipe for designing functional high-susceptibility and low-strain magnetic materials.

Zhou, Chao; Ren, Shuai; Bao, Huixin; Yang, Sen; Yao, Yonggang; Ji, Yuanchao; Ren, Xiaobing; Matsushita, Yoshitaka; Katsuya, Yoshio; Tanaka, Masahiko; Kobayashi, Keisuke

2014-03-01

291

(Tb_1-xY_x)Ni_2Ge_2: From Ising Antiferromagnet to Ising Spin Glass.  

NASA Astrophysics Data System (ADS)

Recent measurements [1,2] on single crystals of RNi_2Ge2 compounds have revealed complex, anisotropies and H-T phase diagrams. In addition recent work on (Gd_1-xEu_x)Ni_2Ge2 has demonstrated our ability to change the band filling so as to tune the ordering wave-vector of the magnetically ordered state [3]. In this talk we will present the results of measurements on another pseudo- ternary series: (Tb_1-xY_x)Ni_2Ge_2. The Tb local moments are aligned along the crystallographic c-axis for all concentrations of Y and as Y replaces Tb the two magnetic transition temperatures decrease rapidly. For x > 0.6 the low temperature ground state of the magnetic sublattice is that of an Ising spin glass. T -x phase diagrams and detailed characterization of the spin glass state will be presented. [1]S.L.Bud'ko et al. JMMM 205, 53 (1999). [2]Z.Islam et al. PRB 58, 8522 (1998). [3]Z.Islam et al. PRL 83, 2817 (1999). Ames Laboratory is operated for the US Department of Energy by Iowa State University under Contract No. W-7405-Eng-82. This work was supported by the Director for Energy Research, Office of Basic Energy Sciences.

Canfield, P. C.; Wiener, T.; Bud'Ko, S. L.

2000-03-01

292

A new [open quotes]123[close quotes] family: LnBa[sub 2]Fe[sub 3]O[sub z]. III. Ln = Gd  

SciTech Connect

An electron diffraction and microscopy study performed on the system LnBa[sub 2]Fe[sub 3]O[sub z] has shown the presence of new perovskite-related superstructures as a function of both Ln and oxygen stoichiometry. These materials constitute the members n = 1 (Ln = Dy, Ho), n = 3/2 (Ln = Gd), n = 4/3 (Ln = Gd, when overheated at 1300[degrees]C for 15 days), and n = 2 (Ln = Nd) of a homologous series with the general formula Ln[sub 1/3]Ba[sub 2/3]FeO[sub 3[minus](1/2n+1)]. A modulated structural approach to LnBa[sub 2]Fe[sub 3]O[sub z] over the description of these phases is discussed.

Garcia-Gonzalez, E.; Parras, M.; Gonzalez-Calbet, J.M. (Universidad Complutense, Madrid (Spain)); Vallet-Regi, M. (Instituto de Magnetismo Aplicado, Correos (Spain))

1994-05-01

293

Purification and characterization of two DyP isozymes from Thanatephorus cucumeris Dec 1 specifically expressed in an air-membrane surface bioreactor.  

PubMed

DyP isozymes (DyP2 and DyP3) from the culture fluid of the fungus Thanatephorus cucumeris Dec 1 by air-membrane surface bioreactor were purified and characterized. The characteristics of DyP2 were almost the same as those of a recombinant DyP reported previously, but different from DyP3. PMID:19217546

Shimokawa, Takuya; Shoda, Makoto; Sugano, Yasushi

2009-02-01

294

Rare-earth chromium gallides RE{sub 4}CrGa{sub 12} (RE=Tb-Tm)  

SciTech Connect

The ternary rare-earth-metal chromium gallides RE{sub 4}CrGa{sub 12} (RE=Tb-Tm) have been prepared by reactions of the elements at 1000 Degree-Sign C in the presence of excess gallium used as a self-flux. Their structures are derived by inserting Cr atoms into a quarter of the empty Ga{sub 6} octahedral clusters found in the parent binary gallides REGa{sub 3} (AuCu{sub 3}-type), although single-crystal X-ray diffraction studies suggest that complex superstructures may be adopted. An ideal ordered Y{sub 4}PdGa{sub 12}-type structure was successfully refined for a crystal of Dy{sub 4}CrGa{sub 12} (Pearson symbol cI34, space group Im3{sup Macron }m, Z=2, a=8.572(1) A). Magnetic measurements on single-crystal samples reveal ferromagnetic or possibly ferrimagnetic ordering for the Tb, Dy, and Er members (T{sub C}=22, 15, and 2.8 K, respectively) and antiferromagnetic ordering for the Ho member (T{sub N}=7.5 K). Band structure calculations on a hypothetical 'Y{sub 4}CrGa{sub 12}' model suggest that the Cr atoms carry no local magnetic moment. - Graphical abstract: RE{sub 4}CrGa{sub 12} is derived by inserting Cr atoms into empty Ga{sub 6} octahedral clusters present in the parent binary gallides REGa{sub 3}. Highlights: Black-Right-Pointing-Pointer RE{sub 4}MGa{sub 12} (previously known for M=Fe, Ni, Pd, Pt, Ag) has been extended to M=Cr. Black-Right-Pointing-Pointer RE{sub 4}CrGa{sub 12} compounds show predominantly ferromagnetic ordering. Black-Right-Pointing-Pointer Band structure calculations suggest that Cr atoms carry no local magnetic moment.

Slater, Brianna R.; Bie, Haiying; Stoyko, Stanislav S. [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada)] [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada); Bauer, Eric D.; Thompson, Joe D. [Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)] [Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Mar, Arthur, E-mail: arthur.mar@ualberta.ca [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada)] [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada)

2012-12-15

295

Preparation and Mechanical Properties of Large Single Domain DyBaCuO Superconductor  

Microsoft Academic Search

We prepared large single domain of DyBaCuO (Dy-123) superconductor for future applications such as a superconducting flywheel for energy storage system, magnetic separation, and a bulk magnet. Dy-123 superconductors are expected to have high and trapped field properties. Melt-textured single domain of Dy-123 system superconductor about 48 mm in diameter and 10 mm in thickness was fabricated with a seeding

H. Fujimoto; H. Shimada; S. Yoshizawa

2008-01-01

296

Myoblast transplantations lead to the expression of the laminin alpha 2 chain in normal and dystrophic (dy/dy) mouse muscles.  

PubMed

Laminin-2 is part of the basement membrane of the skeletal muscle fibers. The laminin alpha 2 chain is absent or drastically reduced in a subgroup of congenital muscular dystrophy patients, and in the severely affected dystrophic dy/dy mouse. We previously reported that heterogeneous primary mouse muscle cell cultures conferred laminin alpha 2 chain expression in dy/dy mice muscles upon cell transplantation. In the present study we investigated whether pure myoblast cell lines were able to confer laminin alpha 2 chain expression in vivo. We observed that: (1) xeno-transplantation of non-immortalized human myoblast in SCID mouse muscles allows human laminin alpha 2 chain expression; (2) allotransplantation of the permanent G8 mouse myoblast cell line in dy/dy muscles allows the expression of the murine laminin alpha 2 chain; and (3) allo-transplantation of the D7 dystrophic dy/dy cell line allows the formation of new and hybrid muscle fibers in dy/dy muscle in the absence of laminin alpha 2 chain expression. We conclude that normal myoblasts are able to restore the expression of an extracellular skeletal muscle protein and that the absence of laminin-2 does not prevent transplanted muscle cells from participating in the formation of myofibers. Myoblasts are, therefore, attractive tools for further exploration of gene complementation strategies in the animal models of congenital muscular dystrophy. PMID:10505103

Vilquin, J T; Guérette, B; Puymirat, J; Yaffe, D; Tomé, F M; Fardeau, M; Fiszman, M; Schwartz, K; Tremblay, J P

1999-05-01

297

Molecular analysis of the Drosophila miniature-dusky ( m-dy) gene complex: m-dy mRNAs encode transmembrane proteins with similarity to C. elegans cuticulin.  

PubMed

Mutations in the Drosophila miniature-dusky ( m-dy) gene complex were first reported by Morgan and Bridges about 90 years ago. m-dy mutants have abnormally small wings, a phenotype attributed to a cell-autonomous reduction in the size of the epidermal cells comprising the differentiated wing. Using a molecular genetic approach, we have characterized the m-dy chromosomal interval and identified a pair of adjacent transcription units corresponding to m and dy. A dy mutant known as dy (And) has a single base substitution within the protein-coding region that is predicted to result in an amber stop codon and premature translational termination. We show that dy mRNA is expressed at two discrete periods during the life cycle--one during embryonic development and early larval instars, the second during adult development, coincident with wing differentiation. In agreement with the phenotypic similarity of m and dy mutants, sequence comparisons reveal a similarity between the predicted MINIATURE and DUSKY proteins, and indicate that the m and dy genes are members of a larger Drosophila gene family. Both m and dy, as well as other members of this superfamily, are predicted to encode transmembrane proteins with similarity to C. elegans cuticle proteins known as cuticulins. We postulate that m, dy and other members of this protein superfamily function as structural components of the Drosophila cuticulin layer. Such a role for m and dy products in wing differentiation is sufficient to explain the morphological phenotypes associated with m-dy mutants. PMID:12172795

DiBartolomeis, S M; Akten, B; Genova, G; Roberts, M A; Jackson, F R

2002-07-01

298

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

299

Atomic deuterium emission from palladium deuteride PdDy surface.  

NASA Astrophysics Data System (ADS)

Deuterium desorption from the surface of decomposing palladium deuteride was studied by monitoring the atomic component of the desorbing gas using an adsorption method. A thin gold film was applied as an adsorbent active for D adsorption, but inert to D2 adsorption. The deuterium deposit thereby collected on the Au surface was analysed by means of the thermal desorption mass spectrometry (TDMS). The atomic component of deuterium, arising by desorption from decomposing PdDy was clearly detected. The experimental results obtained for PdDy, are compared with those observed during the decomposition of PdHx.

Nowicka, Ewa; Wolfram, Zbigniew; Lisowski, Wojciech; Dus, Ryszard

300

Light emission efficiency and imaging performance of Gd{sub 2}O{sub 2}S:Eu powder scintillator under x-ray radiography conditions  

SciTech Connect

Purpose: To evaluate Gd{sub 2}O{sub 2}S:Eu powder phosphor as a radiographic image receptor and to compare it to phosphors often used in radiography. Gd{sub 2}O{sub 2}S:Eu is nonhygroscopic, emitting red light with decay time close to that of Gd{sub 2}O{sub 2}S:Tb. Methods: The light intensity emitted per unit of x-ray exposure rate (absolute luminescence efficiency) was measured for laboratory prepared screens with coating thicknesses of 33.1, 46.4, 63.1, 78.3, and 139.8 mg/cm{sup 2} and tube voltages ranging from 50 to 140 kVp. Parameters related to image quality such as the modulation transfer function (MTF) and the detective quantum efficiency (DQE) were also experimentally examined. In addition, a previously validated Monte Carlo code was used to estimate intrinsic x-ray absorption and optical properties, as well as the MTF and the Swank factor (I) of the Gd{sub 2}O{sub 2}S:Eu scintillators. Results: Gd{sub 2}O{sub 2}S:Eu light intensity was found higher than that of single CsI:Tl crystal for tube voltages up to 100 kVp. The MTF and the DQE were found to be comparable with those of Gd{sub 2}O{sub 2}S:Tb and CsI:Tl screens. MTF estimated by the Monte Carlo code was found very close to the experimental MTF values. Gd{sub 2}O{sub 2}S:Eu showed peak emission in the wavelength range 620-630 nm. Its emission spectrum was excellently matched to various optical detectors (photodiodes, photocathodes, CCDs, and CMOS) employed in flat panel detectors. Conclusions: Gd{sub 2}O{sub 2}S:Eu is an efficient phosphor potentially well suited to radiography and especially to some digital detectors sensitive to red light.

Michail, C. M.; Fountos, G. P.; Liaparinos, P. F.; Kalyvas, N. E.; Valais, I.; Kandarakis, I. S.; Panayiotakis, G. S. [Department of Medical Physics, Faculty of Medicine, University of Patras, 265 00 Patras (Greece); Department of Medical Instruments Technology, Technological Educational Institute, 122 10 Athens (Greece); Department of Medical Physics, Faculty of Medicine, University of Patras, 265 00 Patras (Greece)

2010-07-15

301

Chest Radiographs for Pediatric TB Diagnosis: Interrater Agreement and Utility  

PubMed Central

The chest radiograph (CXR) is considered a key diagnostic tool for pediatric tuberculosis (TB) in clinical management and endpoint determination in TB vaccine trials. We set out to compare interrater agreement for TB diagnosis in western Kenya. A pediatric pulmonologist and radiologist (experts), a medical officer (M.O), and four clinical officers (C.Os) with basic training in pediatric CXR reading blindly assessed CXRs of infants who were TB suspects in a cohort study. C.Os had access to clinical findings for patient management. Weighted kappa scores summarized interrater agreement on lymphadenopathy and abnormalities consistent with TB. Sensitivity and specificity of raters were determined using microbiologically confirmed TB as the gold standard (n = 8). A total of 691 radiographs were reviewed. Agreement on abnormalities consistent with TB was poor; k = 0.14 (95% CI: 0.10–0.18) and on lymphadenopathy moderate k = 0.26 (95% CI: 0.18–0.36). M.O [75% (95% CI: 34.9%–96.8%)] and C.Os [63% (95% CI: 24.5%–91.5%)] had high sensitivity for culture confirmed TB. TB vaccine trials utilizing expert agreement on CXR as a nonmicrobiologically confirmed endpoint will have reduced specificity and will underestimate vaccine efficacy. C.Os detected many of the bacteriologically confirmed cases; however, this must be interpreted cautiously as they were unblinded to clinical features. PMID:25197271

Kaguthi, G.; Nduba, V.; Nyokabi, J.; Onchiri, F.; Gie, R.; Borgdorff, M.

2014-01-01

302

Integrating patients’ perspectives into integrated TB/HIV healthcare  

PubMed Central

Background Escalating rates of TB/HIV coinfection call for improved coordination of TB and HIV healthcare services in high-burden countries such as South Africa. Patient perspectives, however, are poorly understood in the context of current integration efforts. Method Under a qualitative research framework, we interviewed 40 HIV-positive adult TB patients and 8 key-informant healthcare workers across 3 clinics in KwaZulu-Natal province to explore non-clinical and non-operational aspects of TB/HIV healthcare. Findings Qualitative analysis highlighted critical social and ethical considerations for the concurrent delivery of TB and HIV care. Coinfected patients navigating between TB and HIV programs are exposed to missed opportunities for TB and HIV service integration, fragmented or vertical care for their dual infections, and contrasting experiences within TB and HIV clinics. These intersecting issues appear to affect patients’ health-related decisions, particularly HIV nondisclosure to non-HIV healthcare workers, and their preferences for integrated healthcare. Conclusion Our study highlights the imperative to address service fragmentation, HIV medical confidentiality and provider mistrust within the healthcare system, and the cultural differences associated with TB and HIV disease control. PMID:23407149

Daftary, Amrita; Padayatchi, Nesri

2013-01-01

303

Chest Radiographs for Pediatric TB Diagnosis: Interrater Agreement and Utility.  

PubMed

The chest radiograph (CXR) is considered a key diagnostic tool for pediatric tuberculosis (TB) in clinical management and endpoint determination in TB vaccine trials. We set out to compare interrater agreement for TB diagnosis in western Kenya. A pediatric pulmonologist and radiologist (experts), a medical officer (M.O), and four clinical officers (C.Os) with basic training in pediatric CXR reading blindly assessed CXRs of infants who were TB suspects in a cohort study. C.Os had access to clinical findings for patient management. Weighted kappa scores summarized interrater agreement on lymphadenopathy and abnormalities consistent with TB. Sensitivity and specificity of raters were determined using microbiologically confirmed TB as the gold standard (n = 8). A total of 691 radiographs were reviewed. Agreement on abnormalities consistent with TB was poor; k = 0.14 (95% CI: 0.10-0.18) and on lymphadenopathy moderate k = 0.26 (95% CI: 0.18-0.36). M.O [75% (95% CI: 34.9%-96.8%)] and C.Os [63% (95% CI: 24.5%-91.5%)] had high sensitivity for culture confirmed TB. TB vaccine trials utilizing expert agreement on CXR as a nonmicrobiologically confirmed endpoint will have reduced specificity and will underestimate vaccine efficacy. C.Os detected many of the bacteriologically confirmed cases; however, this must be interpreted cautiously as they were unblinded to clinical features. PMID:25197271

Kaguthi, G; Nduba, V; Nyokabi, J; Onchiri, F; Gie, R; Borgdorff, M

2014-01-01

304

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

305

Characteristics and Programme-Defined Treatment Outcomes among Childhood Tuberculosis (TB) Patients under the National TB Programme in Delhi  

PubMed Central

Background Childhood tuberculosis (TB) patients under India's Revised National TB Control Programme (RNTCP) are managed using diagnostic algorithms and directly observed treatment with intermittent thrice-weekly short-course treatment regimens for 6–8 months. The assignment into pre-treatment weight bands leads to drug doses (milligram per kilogram) that are lower than current World Health Organization (WHO) guidelines for some patients. Objectives The main aim of our study was to describe the baseline characteristics and treatment outcomes reported under RNTCP for registered childhood (age <15 years) TB patients in Delhi. Additionally, we compared the reported programmatic treatment completion rates between children treated as per WHO recommended anti-TB drug doses with those children treated with anti-TB drug doses below that recommended in WHO guidelines. Methods For this cross-sectional retrospective study, we reviewed programme records of all 1089 TB patients aged <15 years registered for TB treatment from January to June, 2008 in 6 randomly selected districts of Delhi. WHO disease classification and treatment outcome definitions are used by RNTCP, and these were extracted as reported in programme records. Results and Conclusions Among 1074 patients with records available, 651 (61%) were females, 122 (11%) were <5 years of age, 1000 (93%) were new cases, and 680 (63%) had extra-pulmonary TB (EP-TB)—most commonly peripheral lymph node disease [310 (46%)]. Among 394 pulmonary TB (PTB) cases, 165 (42%) were sputum smear-positive. The overall reported treatment completion rate was 95%. Similar reported treatment completion rates were found in all subgroups assessed, including those patients whose drug dosages were lower than that currently recommended by WHO. Further studies are needed to assess the reasons for the low proportion of under-5 years of age TB case notifications, address challenges in reaching all childhood TB patients by RNTCP, the accuracy of diagnosis, and the clinical validity of reported programme defined treatment completion. PMID:20967279

Satyanarayana, Srinath; Shivashankar, Roopa; Vashist, Ram Pal; Chauhan, Lakhbir Singh; Chadha, Sarabjit Singh; Dewan, Puneet Kumar; Wares, Fraser; Sahu, Suvanand; Singh, Varinder; Wilson, Nevin Charles; Harries, Anthony David

2010-01-01

306

Optical properties of zincfluorophosphate glasses doped with Dy3+ ions  

NASA Astrophysics Data System (ADS)

Dy3+-doped zincfluorophosphate glasses with composition (in mol%) 44P2O5+17K2O+(30-x) ZnF2+9Al2O3+xDy2O3, x=0.01, 0.5, 1.0 and 2.0 have been prepared by melt quenching technique and were characterized through absorption, emission, excitation spectra and decay curves analysis. The energy levels obtained in the absorption spectrum have been analyzed by using free-ion Hamiltonian model. From the intensities of absorption spectra, Judd-Ofelt intensity parameters have been evaluated and in turn predicted the radiative properties such as radiative transition probability, radiative lifetime and branching ratios. The decay curves are found to be single exponential for lower concentrations (?0.1 mol%) and turns into non-exponential for higher concentrations. The non-exponential decay curves are well fitted to Inokuti-Hirayama model for S=6, which indicates that the energy transfer between the donor and the acceptor is of dipole-dipole nature. The fluorescence lifetime decreases from 0.82 ms to 0.45 ms with increase in Dy3+ ion concentration from 0.01 to 2.0 mol%. The results obtained for PKAZFDy glasses are compared and discussed with the other reported Dy3+: glasses. The chromaticity properties for different concentrations of PKAZFDy glass were calculated from emission spectra and analyzed with Commission International de I'Eclairage (CIE) color diagram.

Sreedhar, V. B.; Ramachari, D.; Jayasankar, C. K.

2013-01-01

307

Pinjia Meng1 David D.Y. Chen2  

E-print Network

Pinjia Meng1 Ning Fang2 Meng Wang3 Huwei Liu3 David D.Y. Chen2 1 Department of Forensic Science, China Peoples Public Security University, Beijing, China 2 Department of Chemistry, University of British Colombia, Vancouver, Canada 3 Department of Chemistry, Peking University, Beijing, China Received

Chen, David D.Y.

308

LOFTrelated semiscale test scene. Water has been dyed red. Hot ...  

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

LOFT-related semiscale test scene. Water has been dyed red. Hot steam blowdown exits semiscale at TAN-609 at A&M complex. Edge of building is along left edge of view. Date: 1971. INEEL negative no. 71-376 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

309

Simulation of the Wiener sausage D.-Y. Yang,1  

E-print Network

Simulation of the Wiener sausage D.-Y. Yang,1 Yu. A. Makhnovskii,1,2 S.-Y. Sheu,3 and S. H. Lin1 1, known as the Wiener sausage, is an important random variable characterizing Brownian motion. A Brownian dynamics simulation is used to study statistical properties of the Wiener sausage volume. We show

Sheu, Sheh-Yi

310

DyKnow Federations: Distributing and Merging Information Among UAVs  

E-print Network

DyKnow Federations: Distributing and Merging Information Among UAVs Fredrik Heintz and Patrick, patdo}@ida.liu.se Abstract--As unmanned aerial vehicle (UAV) applications be- come more complex and versatile there is an increasing need to allow multiple UAVs to cooperate to solve problems which are beyond

Doherty, Patrick

311

Phase separation in ternary Co-Gd-Ti liquids  

NASA Astrophysics Data System (ADS)

The phase equilibria and the solidification behavior of ternary Co-Gd-Ti (Co ?35 at.%) alloys have been investigated. The phase transformation and equilibria in the liquid phase were studied in situ for two alloys, Co30Gd35Ti35 and Co30Gd50Ti20, by combining electrostatic levitation of the samples with high-energy synchrotron x-ray diffraction (XRD) at elevated temperature. The XRD patterns with two diffuse maxima for molten Co30Gd35Ti35 give direct evidence for liquid-liquid phase separation in this composition. In contrast, no indication for phase separation in the Co30Gd50Ti20 alloy is detected. Coarsened microstructures, typical for the phase-separating systems, are observed for the Co30Gd35Ti35, Co25Gd37.5Ti37.5, Co10Gd45Ti45 and Co30Gd20Ti50 cast alloys. Our findings suggest that the stable miscibility gap of binary Gd-Ti extends into the ternary Co-Gd-Ti system (up to about 30 at.% Co). Thermodynamic calculations of the ternary Co-Gd-Ti system by the CALPHAD method are in good agreement with the experimental results.

Han, J. H.; Mattern, N.; Kaban, I.; Holland-Moritz, D.; Bednar?ik, J.; Nowak, R.; Sobczak, N.; Kim, D. H.; Eckert, J.

2013-06-01

312

Phase separation in ternary Co-Gd-Ti liquids.  

PubMed

The phase equilibria and the solidification behavior of ternary Co-Gd-Ti (Co ?35 at.%) alloys have been investigated. The phase transformation and equilibria in the liquid phase were studied in situ for two alloys, Co30Gd35Ti35 and Co30Gd50Ti20, by combining electrostatic levitation of the samples with high-energy synchrotron x-ray diffraction (XRD) at elevated temperature. The XRD patterns with two diffuse maxima for molten Co30Gd35Ti35 give direct evidence for liquid-liquid phase separation in this composition. In contrast, no indication for phase separation in the Co30Gd50Ti20 alloy is detected. Coarsened microstructures, typical for the phase-separating systems, are observed for the Co30Gd35Ti35, Co25Gd37.5Ti37.5, Co10Gd45Ti45 and Co30Gd20Ti50 cast alloys. Our findings suggest that the stable miscibility gap of binary Gd-Ti extends into the ternary Co-Gd-Ti system (up to about 30 at.% Co). Thermodynamic calculations of the ternary Co-Gd-Ti system by the CALPHAD method are in good agreement with the experimental results. PMID:23719025

Han, J H; Mattern, N; Kaban, I; Holland-Moritz, D; Bednar?ik, J; Nowak, R; Sobczak, N; Kim, D H; Eckert, J

2013-06-19

313

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

314

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, 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

2013-01-01

315

AC susceptibility studies of the cooperative paramagnet Tb2Ti2O7  

NASA Astrophysics Data System (ADS)

The cooperative paramagnet Tb2Ti2O7 has generated much interest in the frustrated magnetism community due to the lack of ordering down to temperatures well below its Curie-Weiss temperature which is ˜10 K. Its pyrochlore magnetic lattice and highly anisotropic g-factor suggest a similarity to spin ice (i.e. Dy2Ti2O7 and Ho2Ti2O7), however, the first excited crystal field level is of the same order as the exchange interaction. This presents a novel system where crystal field degeneracy should have an effect as a magnetic field is applied. We present ac susceptibility studies on single and polycrystalline samples over broad ranges of temperature, static magnetic field, and frequency. We find two peaks emerge in the complex susceptibility as a function of temperature in the presence of a static magnetic field, and we discuss the data in terms of the effects of single ion and cooperative behavior. This research is supported by the National Science Foundation.

Ueland, B. G.; Lau, G. C.

2005-03-01

316

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

317

Anti-GD2 antibody therapy for GD2-expressing tumors.  

PubMed

In the development of novel immune therapies for high-risk cancers, one goal is to find tumor targets that are not widely shared by normal cells. One such target is the surface disialoganglioside GD2. This antigen is expressed on the surface of a variety of tumors for which no curative therapies exist for patients with advanced disease. In childhood, the most common GD2-expressing tumor is neuroblastoma. GD2 is also expressed on several other high-risk tumors, including those of neuroectodermal or epithelial origin, virtually all melanomas, and approximately 50% of tumor samples from osteosarcoma and soft-tissue sarcomas. Because of the tumor-selective expression of this molecule, it is an attractive target for tumor-specific therapies such as antibody therapy. Over the last 2 decades, several anti-GD2 antibodies have been developed. To reduce both the toxicity of the antibody and the development of human anti-mouse antibodies (HAMA), research efforts have primarily focused on exploring anti-GD2 antibodies that have progressively more human elements while at the same time reducing the mouse components. This review will examine antibodies currently undergoing clinical testing as well as the most recent advances to improve antibody therapy for patients with GD2-expressing tumors. PMID:20201786

Navid, Fariba; Santana, Victor M; Barfield, Raymond C

2010-03-01

318

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 Rails—TB/ALL. (a) All tank vessels...July 1, 1969, shall have efficient guard rails or bulwarks on decks and bridges....

2013-10-01

319

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 Rails—TB/ALL. (a) All tank vessels...July 1, 1969, shall have efficient guard rails or bulwarks on decks and bridges....

2010-10-01

320

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 Rails—TB/ALL. (a) All tank vessels...July 1, 1969, shall have efficient guard rails or bulwarks on decks and bridges....

2012-10-01

321

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 Rails—TB/ALL. (a) All tank vessels...July 1, 1969, shall have efficient guard rails or bulwarks on decks and bridges....

2011-10-01

322

DNA vaccine expressing the mimotope of GD2 ganglioside induces protective GD2 cross-reactive antibody responses.  

PubMed

The GD2 ganglioside expressed on neuroectodermally derived tumors, including neuroblastoma and melanoma, is weakly immunogenic in tumor-bearing patients and induces predominantly immunoglobulin (Ig)-M antibody responses in the immunized host. Here, we investigated whether interconversion of GD2 into a peptide mimetic form would induce GD2 cross-reactive IgG antibody responses in mice. Screening of the X(15) phage display peptide library with the anti-GD2 monoclonal antibody (mAb) 14G2a led to isolation of mimetic peptide 47, which inhibited the binding of 14G2a antibody to GD2-positive tumor cells. The peptide was also recognized by GD2-specific serum antibodies from a patient with neuroblastoma, suggesting that it bears an internal image of GD2 ganglioside expressed on the tumor cells. The molecular basis for antigenicity of the GD2 mimetic peptide, established by molecular modeling and mutagenesis studies, led to the generation of a 47-LDA mutant with an increased mimicry to GD2. Immunization of mice with peptide 47-LDA-encoded plasmid DNA elicited GD2 cross-reactive IgG antibody responses, which were increased on subsequent boost with GD2 ganglioside. The vaccine-induced antibodies recognized GD2-positive tumor cells, mediated complement-dependent cytotoxicity, and exhibited protection against s.c. human GD2-positive melanoma growth in the severe combined immunodeficient mouse xenograft model. The results from our studies provide insights into approaches for boosting GD2 cross-reactive IgG antibody responses by minigene vaccination with a protective epitope of GD2 ganglioside. PMID:15833876

Bolesta, Elizabeth; Kowalczyk, Aleksandra; Wierzbicki, Andrzej; Rotkiewicz, Piotr; Bambach, Barbara; Tsao, Chun-Yen; Horwacik, Irena; Kolinski, Andrzej; Rokita, Hanna; Brecher, Martin; Wang, Xinhui; Ferrone, Soldano; Kozbor, Danuta

2005-04-15

323

Latent TB Infection Diagnosis in Population Exposed to TB Subjects in Close and Poor Ventilated High TB Endemic Zone in India  

PubMed Central

Background The present study was designed to investigate the utility of Quantiferon TB gold (QFT-G) and Tuberculin skin test (TST) for diagnosis of latent TB infection (LTBI) in high crowding TB endemic zone of Nagpur, India and their comparison with associated risk factors. Methods Out of 342 eligible participants, QFT-G and TST were performed in 162 participants. Results The prevalence of LTBI observed according to QFT-G and TST was 48% and 42% respectively, with an agreement of 52.47%. QFT-G positivity was associated with age while TST positivity was associated with body mass index (BMI). Duration of exposure emerged as a key risk factor significantly associated with both the tests. Conclusion The prevalence of LTBI was quite high in the studied zone as detected by both the evaluated tests and thus, the combination of both the tests will be best predictive for LTBI in such high TB endemic regions. PMID:24614179

Kashyap, Rajpal S.; Nayak, Amit R.; Gaherwar, Hari M.; Husain, Aliabbas A.; Shekhawat, Seema D.; Jain, Ruchika K.; Panchbhai, Milind S.; Raje, Dhananjay V.; Purohit, Hemant J.; Taori, Girdhar M.; Daginawala, Hatim F.

2014-01-01

324

Prevalence of pulmonary TB and spoligotype pattern of Mycobacterium tuberculosis among TB suspects in a rural community in Southwest Ethiopia  

PubMed Central

Background In Ethiopia where there is no strong surveillance system and state of the art diagnostic facilities are limited, the real burden of tuberculosis (TB) is not well known. We conducted a community based survey to estimate the prevalence of pulmonary TB and spoligotype pattern of the Mycobacterium tuberculosis isolates in Southwest Ethiopia. Methods A total of 30040 adults in 10882 households were screened for pulmonary TB in Gilgel Gibe field research centre in Southwest Ethiopia. A total of 482 TB suspects were identified and smear microscopy and culture was done for 428 TB suspects. Counseling and testing for HIV/AIDS was done for all TB suspects. Spoligotyping was done to characterize the Mycobacterium tuberculosis isolates. Results Majority of the TB suspects were females (60.7%) and non-literates (83.6%). Using smear microscopy, a total of 5 new and 4 old cases of pulmonary TB cases were identified making the prevalence of TB 30 per 100,000. However, using the culture method, we identified 17 new cases with a prevalence of 76.1 per 100,000. There were 4.3 undiagnosed pulmonary TB cases for every TB case who was diagnosed through the passive case detection mechanism in the health facility. Eleven isolates (64.7%) belonged to the six previously known spoligotypes: T, Haarlem and Central-Asian (CAS). Six new spoligotype patterns of Mycobacterium tuberculosis, not present in the international database (SpolDB4) were identified. None of the rural residents was HIV infected and only 5 (5.5%) of the urban TB suspects were positive for HIV. Conclusion The prevalence of TB in the rural community of Southwest Ethiopia is low. There are large numbers of undiagnosed TB cases in the community. However, the number of sputum smear-positive cases was very low and therefore the risk of transmitting the infection to others may be limited. Active case finding through health extension workers in the community can improve the low case detection rate in Ethiopia. A large scale study on the genotyping of Mycobacterium tuberculosis in Ethiopia is crucial to understand transmission dynamics, identification of drug resistant strains and design preventive strategies. PMID:22414165

2012-01-01

325

Role of H164 in a unique dye-decolorizing heme peroxidase DyP.  

PubMed

The expression system of a unique dye-decolorizing peroxidase DyP in Escherichia coli has been constructed. The molecular mass of the expressed DyP (eDyP) is 47kDa, indicating no any modification with saccharides. The characteristics of eDyP were almost the same as those of native DyP from a fungus Thanatephorus cucumeris Dec 1 and recombinant DyP with Aspergillus oryzae except thermostability. As H164 was suggested to be the proximal histidine based on the preliminary X-ray crystallographic analysis of DyP, the site-directed mutations H164A and H166A (residue near H164) were introduced into the gene encoding DyP. The specific activity and RZ value of the purified H164A were 1.52U/mg and 0.11, respectively, which were 99.8% and 95% lower than those of eDyP, respectively. On the contrary, those of H166A were not different from those of eDyP. Therefore, H164 was confirmed to be the proximal histidine. PMID:15313183

Sugano, Yasushi; Ishii, Yosuke; Shoda, Makoto

2004-09-10

326

The Ras antagonist, farnesylthiosalicylic acid (FTS), decreases fibrosis and improves muscle strength in dy/dy mouse model of muscular dystrophy.  

PubMed

The Ras superfamily of guanosine-triphosphate (GTP)-binding proteins regulates a diverse spectrum of intracellular processes involved in inflammation and fibrosis. Farnesythiosalicylic acid (FTS) is a unique and potent Ras inhibitor which decreased inflammation and fibrosis in experimentally induced liver cirrhosis and ameliorated inflammatory processes in systemic lupus erythematosus, neuritis and nephritis animal models. FTS effect on Ras expression and activity, muscle strength and fibrosis was evaluated in the dy(2J)/dy(2J) mouse model of merosin deficient congenital muscular dystrophy. The dy(2J)/dy(2J) mice had significantly increased RAS expression and activity compared with the wild type mice. FTS treatment significantly decreased RAS expression and activity. In addition, phosphorylation of ERK, a Ras downstream protein, was significantly decreased following FTS treatment in the dy(2J)/dy(2J) mice. Clinically, FTS treated mice showed significant improvement in hind limb muscle strength measured by electronic grip strength meter. Significant reduction of fibrosis was demonstrated in the treated group by quantitative Sirius Red staining and lower muscle collagen content. FTS effect was associated with significantly inhibition of both MMP-2 and MMP-9 activities. We conclude that active RAS inhibition by FTS was associated with attenuated fibrosis and improved muscle strength in the dy(2J)/dy(2J) mouse model of congenital muscular dystrophy. PMID:21445359

Nevo, Yoram; Aga-Mizrachi, Shlomit; Elmakayes, Edva; Yanay, Nurit; Ettinger, Keren; Elbaz, Moran; Brunschwig, Zivia; Dadush, Oshrat; Elad-Sfadia, Galit; Haklai, Roni; Kloog, Yoel; Chapman, Joab; Reif, Shimon

2011-01-01

327

Ground State Magnetic Properties of Odd Neutron DY Isotopes  

NASA Astrophysics Data System (ADS)

Using the quasiparticle phonon nuclear model (QPNM) and taking into account the spin-spin interaction, the effects of the spin polarization on spin gyromagnetic factors (gs) as well as the intrinsic magnetic moments (gK) of the deformed odd neutron 155-165Dy isotopes were studied. The calculated values of gs and gK are in fair agreement with the experiment as well as with other microscopic calculations. Our calculations indicated that because of the core polarization, the gs factors of the nucleons in the nucleus reduce noticeably from its free nucleon value and the spin-spin interactions play an important role in the explanation of the quenching of the gs factors. A very good reproduction of the phenomenological quenching of gs factor from its free values (gs eff = 0.6-0.7gs free) is obtained for 155-165Dy.

Yakut, Hakan; Tabar, Emre; Kuliev, Ali Akbar; Zenginerler, Zemine; Kaplan, Pinar

2013-10-01

328

Immigrants and health system challenges to TB control in Oman  

PubMed Central

Background During the past three decades, Oman has made significant progress in controlling TB within it's borders. However, the national TB control program elimination target has yet to be reached. This study aims to explore the perceived roles played by the immigrant population and the private health sector in relation to TB control in Oman. Methods We conducted seventeen interviews with different health care providers. The verbatim transcripts were processed using content analysis. Results Three main themes emerged. Firstly the threat of repatriation faced by underprivileged expatriates, secondly the criticized and forgotten private health sector as a key player and thirdly the user and provider barriers faced by Omani patients in the Omani public health system. Conclusions The study has identified some of the challenges and barriers to TB control in Oman. These challenges are mainly related to unintended negative consequences arising from the current repatriation policy of immigrants and to and the lack of involvement of the private sector in TB control. TB control strategies designed to address these challenges are needed, for Oman to reach its TB elimination targets. PMID:20637062

2010-01-01

329

Thermochemical investigations in the system Cd-Gd  

PubMed Central

Vapour pressure measurements were performed in terms of a non-isothermal isopiestic method to determine vapour pressures of Cd in the system Cd–Gd between 693 and 1045 K. From these results thermodynamic activities of Cd were derived as a function of temperature for the composition range 52–86 at.% Cd. By employing an adapted Gibbs–Helmholtz equation, partial molar enthalpies of mixing of Cd were obtained for the corresponding composition range, which were used to convert the activity values of Cd to a common average sample temperature of 773 K. The relatively large variation of the activity across the homogeneity ranges of the phases Cd2Gd and Cd45Gd11 indicates that they probably belong to the most stable intermetallic compounds in this system. An activity value of Gd for the two phase field Cd6Gd+L was available from literature and served as an integration constant for a Gibbs–Duhem integration. Integral Gibbs energies are presented between 51 and 100 at.% Cd at 773 K, referred to Cd(l) and ?-Gd(s) as standard states. Gibbs energies of formation for the exact stoichiometric compositions of the phases Cd58Gd13, Cd45Gd11, Cd3Gd and Cd2Gd were obtained at 773 K as about ?19.9, ?21.1, ?24.8, and ?30.0 kJ g atom?1, respectively. PMID:25328283

Reichmann, Thomas L.; Ganesan, Rajesh; Ipser, Herbert

2014-01-01

330

New 0+ states in 158Gd  

Microsoft Academic Search

A new high-precision (p,t) study of the 158Gd nucleus was carried out with the Q3D spectrometer at the University of Munich. The result is the observation for the first time of a deformed nucleus with 13 excited 0+ states below an excitation energy of approximately 3.1 MeV. Seven of these 0+ states are observed for the first time and an

S. R. Lesher; A. Aprahamian; L. Trache; A. Oros-Peusquens; S. Deyliz; A. Gollwitzer; R. Hertenberger; B. D. Valnion; G. Graw

2002-01-01

331

Reductive alkylation of lysine residues in subtilisin DY.  

PubMed

Only lysine epsilon-amino groups (and the N-terminal alpha-amino group) in native subtilisin DY were reductively alkylated by glyceraldehyde in the presence of sodium cyanoborohydride. The modified protein molecule was cleaved by TosPheCH2Cl-trypsin or cyanogen bromide and the two sets of peptides obtained were fractionated and purified by gel filtration and HPLC. For determination of the degree of modification of each lysine residue, selected peptides were subjected to sequence analysis combined with quantitative estimation of the containing PTH-Lys and PTH-epsilon-DHP-Lys. The data obtained showed that the lysine residues in positions 12, 15, 27, 43, 136, 141, 265 were entirely modified, those in positions 170, 184, 237 were partially modified, and Lys22 and Lys94 were unaccessible for the reagent. The caseinolytic activity decreased by 23% when the maximum number of lysine residues (8.6 of the total 12 residues) in subtilisin DY were modified. The CD-spectra of native and modified enzyme showed only slight differences. Both these experiments suggest that the lysine residues do not take part directly in the catalytic reaction but are responsible for maintaining the native three-dimensional enzyme structure. The data obtained for the accessibility of the different lysine residues in subtilisin DY correlated very well with the positions of these residues in a video model of the structure of subtilisin Carlsberg, thus suggesting that the spatial structures of these two enzymes are very similar. PMID:3124865

Lilova, A; Kleinschmidt, T; Nedkov, P

1987-11-01

332

Mechanical properties of DyBaCuO superconducting bulks  

NASA Astrophysics Data System (ADS)

Melt-processed REBaCuO (RE: rare earth) superconductors have a high Jc at 77 K and a high magnetic field, which are expected to be used for high field applications such as superconducting permanent magnets with liquid nitrogen refrigeration, flywheels, current leads and so on. Mechanical properties such as flexural strength, fracture toughness and ductility are very crucial as well as the superconducting properties: Tc, Jc, and Hirr for industrial applications of high- Tc oxide superconductors. However, oxide superconductors have the intrinsic brittleness of the perovskite structure, thus, the strength and the fracture toughness of REBaCuO superconductors have been reported to be low and anisotropic. Therefore, we should investigate and improve mechanical properties to achieve structural reliability for applications. Large single domain of melt-processed REBaCuO (Dy-123) superconductors with Dy 2BaCuO 5 (Dy-211) particles and Ag 2O of 10 wt% was fabricated with a seeding and temperature gradient method in air. In this study, we discuss mechanical properties such as the hardness and the surface roughness, and the flexural strength of the RE-123 bulk, measured at RT. The results of Vickers hardness, surface roughness and the flexural strength showed very important information for evaluating characteristics of RE-123 bulks.

Fujimoto, H.; Shimada, H.; Yoshizawa, S.

2007-10-01

333

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-Loembé, Marguerite; Ceulemans, Ann; Worodria, William; Mayanja-Kizza, Harriet; Colebunders, Robert; Kestens, Luc

2014-01-01

334

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 showi ng 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

335

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

336

Synthesis, structure and magnetic properties of DyAl 2 nanoparticles  

Microsoft Academic Search

DyAl2 nanoparticles have been prepared by means of arc discharge in a mixture of argon and hydrogen gas. The structure of DyAl2 nanoparticles is studied by means of X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. X-ray photoelectron spectroscopy shows that the as-prepared DyAl2 nanoparticles are coated with a layer of Al2O3 phase on the surface, and their

W. S. Zhang; E. H. Brück; Z. D. Zhang; O. Tegus; W. F. Li; P. Z. Si; D. Y. Geng; J. C. P. Klaasse; K. H. J. Buschow

2006-01-01

337

X-ray Absorption spectroscopy and electronic structure calculation of DyScO3  

NASA Astrophysics Data System (ADS)

Dysprosium scandate (DyScO3) is of interest for its potential as a substrate for thin film growth of various materials such as EuTiO3, SrTiO3 BaTiO3 and LaSrMnTiO3 particularly because it creates biaxial strain due to mismatched lattice constant with those materials affecting their properties. We have used X-ray Absorption Spectroscopy to determine the electronic structure of DyScO3. The M4,5 edges of Dy and L2,3 edges of Sc in DyScO3 were investigated against chemically similar materials Dy2O3 and Sc2O3 reference powders and compared with theoretical calculations using LCMO multiplet theory. The spectra are well reproduced by calculations with the given atomic structures, an added crystal field and broadening parameters. We find that the Sc L2,3 edge in DyScO3 is more broadened than in Sc2O3 and the peak position of Dy M4,5 edge in DyScO3 is slightly shifted as compared to those in Dy2O3.

Bhatkar, Harshawardhan; Anderson, B.; Finsterbusch, M.; Rugheimer, P.; Idzerda, Y. U.

2010-10-01

338

Polarization enhancement and ferroelectric switching enabled by interacting magnetic structures in DyMnO3 thin films  

NASA Astrophysics Data System (ADS)

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.

Lu, Chengliang; Dong, Shuai; Xia, Zhengcai; Luo, Hui; Yan, Zhibo; Wang, Haowen; Tian, Zhaoming; Yuan, Songliu; Wu, Tao; Liu, Junming

2013-12-01

339

Fast CW imager for ICG and Gd kinetics  

NASA Astrophysics Data System (ADS)

Gadolinium (Gd) pharmacokinetics are useful in diagnosis of breast cancer with MRI; previous work has suggested that the pharmacokinetics of indocyanine green (ICG) may prove to be similarly useful in optical mammography. Here, we describe a fast optical imaging device to acquire images of ICG kinetics simultaneously with Gd kinetics and coregister the images. This direct comparison between the widely accepted Gd diagnostic techniques and optical methods is essential for clinical acceptance of optical techniques by the radiological community.

Busch, David R., Jr.; Zhao, Zhongyao; Nioka, Shoko; Yodh, Arjun G.; Schnall, Mitchell; Chance, Britton; Intes, Xavier

2006-02-01

340

Laboratory transition probabilities for Gd II (Den Hartog+, 2006)  

Microsoft Academic Search

Radiative lifetimes, accurate to +\\/-5%, have been measured for 49 even-parity and 14 odd-parity levels of GdII 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 GdII transition probabilities and the first using a

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

2008-01-01

341

Studies of sintered MRE-Fe-B magnets by DyF3 addition or diffusion treatment (MRE?=?Nd?+?Y?+?Dy)  

SciTech Connect

Sintered MRE2(Fe, Co)14B magnets by DyF3 blending or diffusion treatment were investigated. “Base-line” magnets with a thickness of 1.5?mm were coated (painted) with DyF3 powder and heated to promote Dy diffusion at 800–900?°C, i.e., “Diffusion” magnets. For comparison, the magnet alloy powder for making Base-line magnets was blended with 3–5?wt.% DyF3 powder and then made into sintered magnets, i.e., “Blended” magnets. The coercivity and (BH)max of Base-line magnets were 9.7 kOe and 32.7 MGOe, respectively, while the coercivity of Diffusion magnets was increased to 15 kOe and the (BH)max was nearly unchanged at 31.4 MGOe. Blended magnets with 5?wt% DyF3 had a coercivity of 17.8 kOe, but the (BH)max was reduced to 25.4 MGOe, due to a considerable reduction of remanence. The total Dy concentration in the MRE2(Fe, Co)14B Diffusion magnets with a ? value of ?0.5%/°C was 5.3?wt%, while typical commercial Nd-based Nd2Fe14B magnets require at least 7.5 wt% Dy to achieve the same ?. Therefore, the MRE2(Fe, Co)14B Diffusion magnets exhibited better temperature stability.

Tang, Wei; Dennis, Kevin W.; Kramer, Matthew; Anderson, Iver, McCallum, Ralph W.

2012-03-13

342

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 Application—TB/ALL. All wood hull tank vessels, the construction or conversion of which was...

2012-10-01

343

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 Application—TB/ALL. All wood hull tank vessels, the construction or conversion of which was...

2013-10-01

344

Modeling TB and HIV co-infections - Department of Mathematics ...  

E-print Network

many societies HIV and TB treatments are common today and the use of drugs .... Definitions of parameters and state variables used in the ...... tuberculosis outbreaks, Journal of Acquired Immune Deficiency Syndromes, 28 (2001), 437–. 444.

2009-09-25

345

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; Stöhr, Joachim; Tsukamoto, Arata; Hecht, Bert; Kimel, Alexey V; Kirilyuk, Andrei; Rasing, Theo; Dürr, Hermann A

2014-01-01

346

Characterization and electronic properties of the Tb/Si(111)7 $times; 7 interface  

NASA Astrophysics Data System (ADS)

The interaction of Tb with Si(111)7 × 7 at room temperature for various Tb coverages has been studied by photoelectron spectroscopy (UPS, XPS), AES and WF measurements. The experimental results indicate that Tb forms a two-dimensional layer up to 2Åas it is shown by the shift of Tb 4f and 4d states. For greater coverages a reaction of Tb and Si starts evidenced by the reacted Si 2p component, and the change of the Si Auger KLL line shape. The interacted interface extends until 12Åof Tb thickness where metallic Tb begins to build up.

Kennou, S.; Veuillen, J.-Y.; Nguyen Tan, T. A.

347

Phase equilibria in Mg-Y-Gd-Sm alloys  

NASA Astrophysics Data System (ADS)

Differential thermal, metallographic, and electron microprobe analyses are used to study the effect of samarium on the temperatures and character of the phase equilibria in Mg-rich Mg-Y-Gd alloys containing up to 5 wt % yttrium or gadolinium and up to 8 wt % samarium. The magnesium solid solution is found to be in equilibrium only with the Mg41Sm5 and Mg24(Y,Gd)5 phases, which belong to the binary Mg-Sm and ternary Mg-Y-Gd systems, respectively. Partial polythermal sections of the Mg-Y-Gd-Sm phase diagram are constructed for the Mg-rich region.

Rokhlin, L. L.; Luk'yanova, E. A.; Dobatkina, T. V.; Alad'ev, N. A.; Korol'kova, I. G.

2012-09-01

348

Ligand-sensitized fluorescence of Tb 3+ in Tb 3+-dibutylphosphate complexes: Application for the estimation of DBP  

NASA Astrophysics Data System (ADS)

The fluorescence of Tb 3+ is sensitized by complexation with dibutylphosphate (DBP) and tri- n-butylphosphate (TBP). The excitation maximum for the Tb 3+-DBP complex occurs at 218.5 nm, while that for the Tb 3+-TBP complex is observed at 228.0 nm. Both complexes yield Tb 3+ fluorescence at 548 nm. The difference in the excitation maxima for the two complexes has been used to advantage for the estimation of DBP in the presence of TBP. DBP is the main degradation product of TBP in the PUREX process and the method described in this work can thus serve as a useful analytical tool in monitoring the quality of the TBP in the process. This method has been shown to be applicable for the estimation of DBP when present to an extent of 0.1-10% of TBP, in TBP/dodecane solutions.

Maji, S.; Viswanathan, K. S.

2006-07-01

349

Ligand-sensitized fluorescence of Tb3+ in Tb3+-dibutylphosphate complexes: application for the estimation of DBP.  

PubMed

The fluorescence of Tb(3+) is sensitized by complexation with dibutylphosphate (DBP) and tri-n-butylphosphate (TBP). The excitation maximum for the Tb(3+)-DBP complex occurs at 218.5 nm, while that for the Tb(3+)-TBP complex is observed at 228.0 nm. Both complexes yield Tb(3+) fluorescence at 548 nm. The difference in the excitation maxima for the two complexes has been used to advantage for the estimation of DBP in the presence of TBP. DBP is the main degradation product of TBP in the PUREX process and the method described in this work can thus serve as a useful analytical tool in monitoring the quality of the TBP in the process. This method has been shown to be applicable for the estimation of DBP when present to an extent of 0.1-10% of TBP, in TBP/dodecane solutions. PMID:16488659

Maji, S; Viswanathan, K S

2006-07-01

350

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

351

Red, Green, and Blue Light Through Cooperative Up-Conversion in Sol-Gel Thin Films Made With Yb0.80La0.15Tb0.05F3 and Yb0.80La0.15Eu0.05F3 Nanoparticles  

NASA Astrophysics Data System (ADS)

Silica and zirconium dioxide sol-gel thin films made with Yb0.80La0.15Tb0.05F3 or Yb0.80La0.15Eu0.05F3 nanoparticles are reported. Bright blue (413 and 435 nm), green (545 nm), and red (585 and 625 nm) emissions are produced from Tb3+ ions through cooperative up-conversion of 980 nm light. Similarly, red (591 and 612 nm) emission is generated from Eu3+ ions. These up-convertors may find use in white light sources. The cooperative up-conversion of Yb3+ - Tb3+ ions is more efficient than of Yb3+ - Eu3+ ions because the efficiency of energy transfer from excited Yb3+ ions to a Tb3+ ion (0.37) is more than two-times higher than of excited Yb3+ ions to a Eu3+ ion (0.15), as estimated from the lifetime of excited Yb3+ ion. The estimated quantum yields of both Tb3+ ion and Eu3+ ion emissions are on the order of 40%, and hence are not the cause of the difference in efficiency. This approach does not work for Sm3+, Pr3+, and Dy3+. Incorporation of the respective Ln3+ ions in nanoparticles is crucial, as controls, in which the various Ln3+ ions are incorporated directly into the sol-gel, that do not show cooperative up-conversion.

Sivakumar, Sri; van Veggel, Frank C. J. M.

2007-06-01

352

GD2 oligosaccharide: target for cytotoxic T lymphocytes  

PubMed Central

Carbohydrate antigens rarely provide target epitopes for cytotoxic T lymphocytes (CTL). Disialoganglioside GD2 is a glycolipid expressed at high levels in human tumors and a small group of murine lymphomas (EL4, RBL5, RMA, RMA-S, A13, and BALBRVE). Immunization of C57B1/6 mice with irradiated EL4 cells stimulated a specific CTL response and protected these animals from engraftment of EL4 lymphoma. The CTL activity resided in the CD4-CD8+ population, was dependent on T cell receptor alpha/beta, and was not removed by anti-natural killer cell immunoabsorption, but was restricted to GD2 and H-2b bearing targets. CTL activity could be completely inhibited by GD2-oligosaccharide- specific monoclonal antibodies and their F(ab')2 fragments, but not by immunoglobulin G3 myelomas or antibodies against GD3 or GM2. Soluble GD2 did not inhibit specific tumor lysis. RMA-S lymphoma cells (GD2+H- 2b-TAP2 deficient) were resistant to GD2-specific CTL. Sialic acid- containing peptides eluted from EL4 lymphoma cells could (a) stabilize H-2 molecules on RMA-S cells and (b) sensitize them for GD2-specific CTL. Control peptides (derived from vesicular stomatitis virus nucleoprotein peptide and GD2-negative lymphomas) could also stabilize H-2 on RMA-S, but were resistant to GD2-specific CTL. These H-2-binding peptides could be purified by anti-GD2 affinity chromatography. We postulate a new class of naturally occurring epitopes for T cells where branched-chain oligosaccharides are linked to peptides with anchoring motifs for the major histocompatibility complex class I pocket. While analogous to the haptens trinitrophenyl and O-beta-linked acetyl- glucosamine, the potential implications of natural carbohydrates as antigenic epitopes for CTL in biology are considerable. PMID:7540657

1995-01-01

353

Integration of HIV and TB services results in improved TB treatment outcomes and earlier, prioritized ART initiation in a large urban HIV clinic in Uganda  

PubMed Central

Background WHO recommends that treatment of TB in HIV-infected patients should be integrated with HIV care. In December 2008, a separate, outdoor integrated TB/HIV clinic was instituted for attendees of a large urban HIV clinic in Uganda. We sought to evaluate associated TB and HIV treatment outcomes. Methods Routinely collected clinical, pharmacy and laboratory data was merged with TB clinic data for patients initiating TB treatment in 2009 and with TB register data for patients in 2007. TB treatment outcomes and (timing of) ART initiation in ART-naïve patients (overall and stratified by CD4+ T cell [CD4] count) in 2007 and 2009 were compared. Nosocomial transmission rates could not be assessed. Results 346 patients were initiated on TB treatment in 2007 and 366 in 2009. Median CD4 counts at TB diagnosis did not differ. TB treatment cure or completion increased from 62% to 68%, death or default decreased from 33% to 25% (P<0.001). Fewer ART naïve TB patients were initiated on ART in 2009 versus 2007 (57% and 66%, P=0.031), but this decrease was only in patients with CD4 counts >250/mm3 (19% versus 48%, P=0.003). More patients were started on ART during TB treatment (94% versus 78%, P<0.001). Moreover, the majority were now initiated during intensive phase (60% versus 23%, P<0.001). Conclusions Integration of TB and HIV care has led to improved TB treatment outcomes and earlier, prioritized ART initiation. This supports roll-out of a fully integrated TB/HIV service delivery model throughout high-prevalence TB and HIV settings. PMID:22395671

Hermans, Sabine M; Castelnuovo, Barbara; Katabira, Catherine; Mbidde, Peter; Lange, Joep MA; Hoepelman, Andy IM; Coutinho, Alex; Manabe, Yukari C

2012-01-01

354

Atomic Mass and Nuclear Binding Energy for Dy-171 (Dysprosium)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Dy-171 (Dysprosium, atomic number Z = 66, mass number A = 171).

Sukhoruchkin, S. I.; Soroko, Z. N.

355

Giant magnetocaloric effect in antiferromagnetic DyVO4 compound  

NASA Astrophysics Data System (ADS)

We have investigated the magnetic and magnetocaloric properties of DyVO4 by magnetization and heat capacity measurements. ?(T) shows antiferromagnetic to paramagnetic transition at TNDy~3.5 K. The compound undergoes a metamagnetic transition and exhibits a huge entropy change. The maximum values of magnetic entropy change (?SM), adiabatic temperature change (?Tad) and refrigerant capacity (RC) reach 26 J kg-1 K-1, 17 K, and 526 J kg-1, respectively for a field change of 0-8 T. Moreover, the material is highly insulating and exhibits no thermal and field hysteresis, satisfying the necessary conditions for a good magnetic refrigerant material.

Midya, A.; Khan, N.; Bhoi, D.; Mandal, P.

2014-09-01

356

Atomic Mass and Nuclear Binding Energy for Dy-227 (Dysprosium)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Dy-227 (Dysprosium, atomic number Z = 66, mass number A = 227).

Sukhoruchkin, S. I.; Soroko, Z. N.

357

Factors limiting the hydrolysis of casein by subtilisin DY.  

PubMed

It was shown that during the subtilisin DY-induced hydrolysis of casein relatively stable polypeptide structures are formed. In their interior these structures contain peptide bonds which are susceptible to the enzyme used. Heating (up to 100 degrees C) and/or application of ultrasound (25 kHz, 60 W) results in their unfolding. Data are provided, which show that under the enzyme-substrate complex formation does not lead to an enzyme conformation more susceptible to autolysis. Taking into account the described phenomena a higher degree of hydrolysis was attained in comparison to those obtained by standard enzymatic hydrolysis. PMID:3322321

Nedkov, P; Lilova, A; Tchorbanov, B

1987-10-01

358

Spectral Properties of Dy-Doped Thermal Barrier Sensor Coatings  

SciTech Connect

We have obtained the excitation (484, 497 and 585 nm) and emission (355, 367 and 385 nm) spectra and measured the fluorescence decay lifetimes for partially Y2O3 stabilized ZrO2 thermal barrier coatings doped with 2mol% Dy2O3, as a function of coating depth for thicknesses ranging from 30 to 200 ?m. In principle, these coatings can function not only as thermal protection barriers for turbomachinery blades and vanes, but also as remotely interrogated self-sensors for use in determining in situ wear rates during operation. This is done by varying the excitation wavelength and observing the fluorescence decay times and related parameters.

Allison, Stephen W [ORNL] [ORNL; Moore, Danielle [ORNL] [ORNL; Heyes, Andrew [Imperial College, London] [Imperial College, London; Nichols, John R. [Cranfield University] [Cranfield University

2009-01-01

359

Reduced Measurement-space Dynamic State Estimation (ReMeDySE) for Power Systems  

E-print Network

Reduced Measurement-space Dynamic State Estimation (ReMeDySE) for Power Systems Jinghe Zhang--Applying Kalman filtering techniques to dynamic state estimation is a developing research area in modern power have developed an approach we call Reduced Measurement-space Dynamic State Estimation (ReMeDySE). We

Bishop, Gary

360

26 CFR 48.4082-1 - Diesel fuel and kerosene; exemption for dyed fuel.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 true Diesel fuel and kerosene; exemption for dyed...Fuel Taxable Fuel § 48.4082-1 Diesel fuel and kerosene; exemption for dyed...on the removal, entry, or sale of any diesel fuel or kerosene if— (1) The...

2010-04-01

361

26 CFR 48.4082-1 - Diesel fuel and kerosene; exemption for dyed fuel.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Diesel fuel and kerosene; exemption for dyed...Fuel Taxable Fuel § 48.4082-1 Diesel fuel and kerosene; exemption for dyed...on the removal, entry, or sale of any diesel fuel or kerosene if— (1) The...

2013-04-01

362

26 CFR 48.4082-1 - Diesel fuel and kerosene; exemption for dyed fuel.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Diesel fuel and kerosene; exemption for dyed...Fuel Taxable Fuel § 48.4082-1 Diesel fuel and kerosene; exemption for dyed...on the removal, entry, or sale of any diesel fuel or kerosene if— (1) The...

2012-04-01

363

26 CFR 48.4082-1 - Diesel fuel and kerosene; exemption for dyed fuel.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Diesel fuel and kerosene; exemption for dyed...Fuel Taxable Fuel § 48.4082-1 Diesel fuel and kerosene; exemption for dyed...on the removal, entry, or sale of any diesel fuel or kerosene if— (1) The...

2011-04-01

364

Element-specific probe of the magnetic and electronic properties of Dy incar-fullerenes.  

PubMed

The magnetic and electronic properties of a single atom and a pair of Dy atoms encapsulated inside fullerene carbon cages have been examined using X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) as well as resonant photoelectron spectroscopy (RESPES) across the Dy M(4,5)-edge. The comparison of the measured XAS spectra with multiplet calculations indicates that the encaged Dy has a 4f( 9) configuration. The presence of Dy 5d spectral weight in the valence band is not detected by RESPES, indicating that Dy is in a formally trivalent state. The evolution of the encaged Dy orbital and spin moments of the 4f orbitals as a function of the applied magnetic field and temperature has been obtained from XMCD measurements. At 6.9 T and 4 K, both the orbital and the spin magnetic moments of the encaged Dy 4f electrons are dramatically smaller than those expected for the free Dy(3+) at saturation. PMID:16599500

Bondino, F; Cepek, C; Tagmatarchis, N; Prato, M; Shinohara, H; Goldoni, A

2006-04-13

365

Calculations of the magnetic entropy change in amorphous through a microscopic anisotropic model: Applications to Dy70Zr30 and DyCo3.4 alloys  

NASA Astrophysics Data System (ADS)

We report theoretical investigations on the magnetocaloric effect, described by the magnetic entropy change in rare earth—transition metal amorphous systems. The model includes the local anisotropy on the rare earth ions in Harris-Plischke-Zuckermann assumptions. The transition metals ions are treated in terms of itinerant electron ferromagnetism and the magnetic moment of rare earth ions is coupled to the polarized d-band by a local exchange interaction. The magnetocaloric effect was calculated in DyCo3.4 system, which presents amorphous sperimagnetic configuration. The calculations predict higher refrigerant capacity in the amorphous DyCo3.4 than in DyCo2 crystal, highlighting the importance of amorphous magnetocaloric materials. Our calculation of the magnetocaloric effect in Dy70Zr30, which presents amorphous asperomagnetic configuration, is in good agreement with the experimental result. Furthermore, magnetic entropy changes associated with crystal-amorphous configurations change are estimated.

von Ranke, P. J.; Nóbrega, E. P.; Caldas, A.; Alho, B. P.; Ribeiro, P. O.; Alvarenga, T. S. T.; Lopes, P. H. O.; de Sousa, V. S. R.; Magnus, A.; Carvalho, G.; de Oliveira, N. A.

2014-10-01

366

Improved muscle strength and mobility in the dy(2J)/dy(2J) mouse with merosin deficient congenital muscular dystrophy treated with Glatiramer acetate.  

PubMed

The therapeutic effect of Glatiramer acetate, an immune modulating agent, was evaluated in the dy(2J)/dy(2J) mouse with merosin deficient congenital muscular dystrophy, which is a milder variant of the dy/dy mouse. The treated mice showed significant improvement in hind limb muscle strength measured by electronic grip strength meter and in motor performance quantified by video detection software. Glatiramer acetate treatment was associated with significantly increased expression of regeneration transcription factors MyoD and myogenin, and attenuation of the fibrosis markers vimentin and fibronectin. No effective treatment is currently available in congenital muscular dystrophy and Glatiramer acetate may present a new potential treatment for this disorder. PMID:20304648

Dadush, Oshrat; Aga-Mizrachi, Shlomit; Ettinger, Keren; Tabakman, Rinat; Elbaz, Moran; Fellig, Yakov; Yanay, Nurit; Nevo, Yoram

2010-04-01

367

Study on the hydrothermal synthesis and optical properties of YVO4:Dy3+ phosphor powders  

NASA Astrophysics Data System (ADS)

YVO4:Dy3+ phosphor powders were synthesized by using the hydrothermal method under different pH conditions. The crystallization, surface morphology, lattice vibration, optical properties, luminescent mechanism and influencing factors of the obtained YVO4:Dy3+ phosphor powders were carefully studied and analyzed in detail. All of the YVO4:Dy3+ phosphor powders had tetragonal structures, and the pH value had a significant impact on the surface morphology, structure and optical properties of the synthesized samples. Strong acidic and alkali environments were favorable for the crystallization of YVO4:Dy3+phosphor powders, and the YVO4:Dy3+ phosphor powders synthesized under strong alkali environments had the best luminescent properties.

Liu, Hong-Tao; Liang, Yan; Gao, Xiao-Yong; Zhang, Sa; Zhao, Xian-Wei; Chen, Xian-Mei

2013-10-01

368

DyP-type peroxidases comprise a novel heme peroxidase family.  

PubMed

Dye-decolorizing peroxidase (DyP) is produced by a basidiomycete (Thanatephorus cucumeris Dec 1) and is a member of a novel heme peroxidase family (DyP-type peroxidase family) that appears to be distinct from general peroxidases. Thus far, 80 putative members of this family have been registered in the PeroxiBase database (http://peroxibase.isbsib.ch/) and more than 400 homologous proteins have been detected via PSI-BLAST search. Although few studies have characterized the function and structure of these proteins, they appear to be bifunctional enzymes with hydrolase or oxygenase, as well as typical peroxidase activities. DyP-type peroxidase family suggests an ancient root compared with other general peroxidases because of their widespread distribution in the living world. In this review, firstly, an outline of the characteristics of DyP from T. cucumeris is presented and then interesting characteristics of the DyP-type peroxidase family are discussed. PMID:19099183

Sugano, Y

2009-04-01

369

Synthesis, structure, magnetism, and optical properties of Cs2Cu3DyTe4.  

PubMed

CsCu(3)DyTe(4) was prepared by reacting copper, dysprosium, and tellurium with cesium azide at 850 °C in a fused silica ampule. This new telluride crystallizes in the monoclinic space group C2/m with lattice dimensions of a = 16.462(4) Å, b = 4.434(1) Å, c = 8. 881(2) Å, ? = 108.609(12)° with Z = 2. Its crystal structure is dominated by (?)(2){[Cu(3)DyTe(4)]}(1-) anionic layers separated by Cs(+) cations. The copper cations are disordered over three different tetrahedral sites. The [DyTe(6)](9-) polyhedra form infinite (?)(1){[DyTe(4)](5-)} chains. Magnetism studies conducted on this semiconductor suggest complex magnetic interactions between the Dy(3+) cations with a strong deviation from Curie-type behavior at low temperatures below 40 K. PMID:23039209

Babo, Jean-Marie; Choi, Eun Sang; Albrecht-Schmitt, Thomas E

2012-11-01

370

Improvement of Light Fastness Properties of Dyed Jute Fabrics Through Pretreatment  

NASA Astrophysics Data System (ADS)

The chemical treatments such as desizing, scouring, caustic soda mercerization, ammonia mercerization at -33°C and bleaching were carried out on jute fabrics. Then dyeing was done with various reactive dyes applying by standard procedure to investigate the change in different properties like light fastness, moisture regain and nitrogen content has been done on undyed and dyed jute products. It was observed that the moisture regain percentage of the jute fabrics increased after different treatments and the moisture regain percentage of dyed fabrics decreased in all the cases. The nitrogen content percentage of the ammonia treated and dyed fabrics were higher than other treated and undyed jute fabrics. Therefore light fastness properties of the ammonia treated and dyed fabrics will be adequate. So, it can be concluded that anhydrous liquid ammonia (-33°C) treatment improves light fastness properties of dyed jute fabrics for the diversification of jute for value addition.

Shahidullah, Md.; Rabiul Islam, Md.; Alamgir Sayeed, M. M.; Kamal Uddin, Md.; Abdullah, A. B. M.

371

Microstructure of Monolithic DyBa2Cu3O7-x Coated Conductor Thick Films  

NASA Astrophysics Data System (ADS)

Five ?m thick DyBa2Cu3O7-x (DyBCO) films were deposited via Inclined Substrate Deposition (ISD) on Hastelloy substrates. A critical current density of 2.0 MA cm-2 was measured resistively at 77 K and self-field yielding 1000 A cm-1. A grain size of 500-600 nm was determined and only small-angle grain boundaries were observed. The DyBCO film is highly biaxially textured and the c-axis encloses an angle of 27±1? with the substrate normal over the complete film thickness. A perfect growth behavior of DyBCO in ISD technology was observed due to the faceted structure of the MgO surface yielding a non-zero component of the growth direction parallel to the (a,b)-plane of the DyBCO.

Dürrschnabel, M.; Aabdin, Z.; Bauer, M.; Große, V.; Semerad, R.; Prusseit, W.; Eibl, O.

372

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

2009-09-28

373

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.; Novák, P.; Kuriplach, J.; Lütgemeier, H.

1990-08-01

374

Spin-ice behavior in Dy2Sn2-xSbxO7+x/2 and Dy2NbScO7  

NASA Astrophysics Data System (ADS)

We report the magnetic and thermal properties of Dy2Sn2-xSbxO7+x/2 ( x=0 , 0.25, and 0.5) and of Dy2NbScO7 . We find evidence for Ising-like single ion ground states in the Dy2Sn2-xSbxO7+x/2 materials. Furthermore, these materials possess nearly the same zero-point entropy as the canonical spin ices Ho2Ti2O7 and Dy2Ti2O7 . These results strongly suggest that the Dy2Sn2-xSbxO7+x/2 materials studied have spin-ice states at low temperatures. We also observe a somewhat reduced zero-point entropy in Dy2NbScO7 , which is possibly associated with a higher level of cation disorder. The icelike states in these materials, despite the cation disorder on the B sites of the pyrochlore lattice, provide evidence for the robust nature of spin-ice behavior in the presence of disorder.

Ke, X.; Ueland, B. G.; West, D. V.; Dahlberg, M. L.; Cava, R. J.; Schiffer, P.

2007-12-01

375

M?ssbauer, EPR, and magnetic susceptibility studies on members of a new family of cyano-bridged 3d-4f complexes. Demonstration of anisotropic exchange in a Fe-Gd complex  

PubMed Central

The synthesis and crystallographic characterization of a new family of M(?-CN)Ln complexes are reported. Two structural series have been prepared by reacting in water rare earth nitrates (LnIII = La, Pr, Nd, Sm, Eu, Gd, Dy, Ho) with K3[M(CN)6] (MIII = Fe, Co) in the presence of hexamethylenetetramine (hmt). The first series consists of six isomorphous heterobinuclear complexes, [(CN)5M-CNLn(H2O)8]·2hmt ([FeLa] 1, [FePr] 2, [FeNd] 3, [FeSm] 4, [FeEu] 5, [FeGd] 6), while the second series consists of four isostructural ionic complexes, [Ln(H2O)8][M(CN)6]·hmt ([FeDy] 7, [FeHo] 8, [CoEu] 9, [CoGd] 10). The hexamethylenetetramine molecules contribute to the stabilization of the crystals by participating in an extended network of hydrogen bond interactions. In both series the aqua ligands are hydrogen bonded to the nitrogen atoms from both the terminal CN groups and the hmt molecules. The [FeGd] complex has been analyzed with 57Fe Mössbauer spectroscopy, EPR, and magnetic susceptibility measurements. We have also analyzed the [FeLa] complex, in which the paramagnetic GdIII is replaced by diamagnetic LaIII, to obtain information about the low-spin FeIII site that is not accessible in the presence of a paramagnetic ion at the complementary site. For the same reason, the [CoGd] complex, containing diamagnetic CoIII, was studied with EPR and magnetic susceptibility measurements, which confirmed the S = 7/2 spin of GdIII. Prior knowledge about the paramagnetic sites in [FeGd] allows a detailed analysis of the exchange interactions between them. In particular, the question of whether the exchange interaction in [FeGd] is isotropic or anisotropic has been addressed. Standard variable-temperature magnetic susceptibility measurements provide only the value for a linear combination of Jx, Jy, and Jz but contain no information about the values of the individual exchange parameters Jx, Jy, and Jz. In contrast, the spin-Hamiltonian analysis of the variable-field, variable-temperature Mössbauer spectra reveals an exquisite sensitivity on the anisotropic exchange parameters. Analysis of these dependencies in conjunction with adopting the g-values obtained for [FeLa], yielded the values Jx = ?1 · J · ?2 +0.11 cm?1, Jy = +0.33 cm?1, and Jz = +1.20 cm?1 (convention). The consistency of these results with magnetic susceptibility data is analyzed. The exchange anisotropy is rooted in the spatial anisotropy of the low-spin FeIII ion. The condition for anisotropic exchange is the presence of low-lying orbital excited states at the ferric site that (i) effectively interact through spin-orbit coupling with the orbital ground state and (ii) have an exchange parameter with the Gd site with a value different from that for the ground state. DFT calculations, without spin-orbit coupling, reveal that the unpaired electron of the t2g5 ground configuration of the FeIII ion occupies the xy orbital, i.e. the orbital along the plane perpendicular to the Fe?Gd vector. The exchange-coupling constants for this orbital, jxy, and the other t2g orbitals, jyz and jxz, have been determined using a theoretical model that relates them to the anisotropic exchange parameters and the g-values of FeIII. The resulting values, jyz = ?5.7 cm?1, jxz = ?4.9 cm?1, and jxy = +0.3 cm?1 are quite different. The origin of the difference is briefly discussed. PMID:20225831

Stoian, Sebastian A.; Paraschiv, Carmen; Kiritsakas, Nathalie; Lloret, Francesc; Munck, Eckard; Bominaar, Emile L.; Andruh, Marius

2010-01-01

376

Study on novel rare-earth nitride chlorides GdNCl and Gd2N2Cl  

NASA Astrophysics Data System (ADS)

We report a joint experimental and theoretical investigation of magnetic and structural properties for novel rare-earth nitride chlorides GdNCl and Gd2N2Cl. By using the method of gas-solid phase reaction at high temperature, a new layered rare-earth nitride chloride GdNCl was synthesized recently. The structure and morphology were characterized by X-ray diffraction and transmission electron microscope. The analysis results show that GdNCl compound has the same crystalline structure as the known phase CeNCl, which crystallized in a tetragonal structure with space group P4/nmm (No.129). The lattice constants are a = b = 4.42 nm, c = 6.46 nm. The layered structure of GdNCl is comprised of the double Gd-N layers and Cl layers. In addition, another new stable phase Gd2N2Cl was also synthesized. The Gd2N2Cl structure belongs to a tetragonal system with P4mm space group (No.99) and lattice constants are a = b = 4.25 nm and c = 5.92 nm. The temperature-dependent magnetic susceptibility measurements (ZFC and FC) were performed, which showed a ferromagnetic transition occurs at 70 K. The first-principle simulation based on the density functional theory was used to investigate the physical properties and structural stability of rare-earth nitride chlorides, which is consistent with the experiments.

Chen, Ning; Liu, Xiuxia; Liu, Yang; Li, Yang

2013-03-01

377

Coherent growth of GaGdN layers with high Gd concentration on GaN(0001)  

SciTech Connect

We report on the coherent growth of GaGdN with high Gd concentration on a GaN template using radio-frequency plasma-assisted molecular beam epitaxy under elevated growth conditions. X-ray diffraction and cross-sectional transmission electron microscopy observations revealed that at a growth temperature of 700 {sup Degree-Sign }C or below, GaGdN layers are coherently grown on the GaN templates without segregation of the secondary phases. As the GdN mole fraction x was increased to 0.08, the c-axis lattice parameter in Ga{sub 1-x}Gd{sub x}N increased linearly. Increasing the growth temperature to 750 {sup Degree-Sign }C causes lattice relaxation in GaGdN. All GaGdN samples exhibited photoluminescence emissions near the band-edge, a blue luminescence band emission, and a green luminescence band emission. The origin of the green luminescence band emission is discussed in relation to the compressive strain existing in the GaGdN layers coherently grown on GaN.

Higashi, K.; Hasegawa, S.; Abe, D.; Mitsuno, Y.; Komori, S.; Ishimaru, M.; Asahi, H. [The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Ishikawa, F. [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

2012-11-26

378

Carbide clusterfullerene Gd2C2@C92 vs dimetallofullerene Gd2@C94: a quantum chemical survey.  

PubMed

The geometric, electronic structure, and thermodynamic stability of Gd2C94 species, including dimetallofullerenes Gd2@C94 and carbide clusterfullerenes Gd2C2@C92, have been systematically investigated by a density functional theory approach combined with statistical mechanics calculations. Although the Gd2@C2(153480)-C94 is determined to possess the lowest energy, its molar fraction at the temperature region of fullerene formation is extremely low if the temperature effect is taken into consideration. Meanwhile, three C92-based carbide clusterfullerene species, Gd2C2@D3(126408)-C92, Gd2C2@C1(126390)-C92, and Gd2C2@C2(126387)-C92, with some higher energy are exposed to possess considerable thermodynamic stabilities within a related temperature interval, suggesting that carbide clusterfullerenes rather than dimetallofullerenes could be isolated experimentally. Although one isomer, Gd2C2@D3(126408)-C92, has been indeed obtained experimentally, a novel structure, Gd2C2@C1(126390)-C92, behaving as the most abundant isomer at more elevated temperatures with the largest SOMO-LUMO gap, is predicted for the first time to be another proper isomer isolated in the experiment. Moreover, in order to further analyze the interaction between gadolinium atoms and carbon atoms in either a carbide cluster or a fullerene cage, frontier molecular orbital, natural bond orbital, and Mayer bond order analyses have been employed, and the results show that the covalent interaction cannot be neglected. The IR spectra of Gd2C2@C92 have been simulated to provide some valuable guidance for future experiments. PMID:24495172

Guo, Yi-Jun; Yang, Tao; Nagase, Shigeru; Zhao, Xiang

2014-02-17

379

In Silico identification of M. TB proteins with diagnostic potential  

PubMed Central

TB, caused by Mycobacterium tuberculosis (MTB), is one of the major global infectious diseases. For the pandemic control, early diagnosis with sensitive and specific methods is fundamental. With the advent of bioinformatics’ tools, the identification of several proteins involved in the pathogenesis of TB (TB) has been possible. In the present work, the MTB genome was explored to look for molecules with possible antigenic properties for their evaluation as part of new generation diagnostic kits based on the release of cytokines. Seven proteins from the MTB proteome and some of their combinations suited the computational test and the results suggested their potential use for the diagnosis of infection in the following population groups: Cuba, Mexico, Malaysia and sub-Saharan Africa. Our predictions were performed using public bioinformatics tools plus three computer programs, developed by our group, to facilitate information retrieval and processing. PMID:23458073

2013-01-01

380

In Silico identification of M. TB proteins with diagnostic potential.  

PubMed

TB, caused by Mycobacterium tuberculosis (MTB), is one of the major global infectious diseases. For the pandemic control, early diagnosis with sensitive and specific methods is fundamental. With the advent of bioinformatics' tools, the identification of several proteins involved in the pathogenesis of TB (TB) has been possible. In the present work, the MTB genome was explored to look for molecules with possible antigenic properties for their evaluation as part of new generation diagnostic kits based on the release of cytokines. Seven proteins from the MTB proteome and some of their combinations suited the computational test and the results suggested their potential use for the diagnosis of infection in the following population groups: Cuba, Mexico, Malaysia and sub-Saharan Africa. Our predictions were performed using public bioinformatics tools plus three computer programs, developed by our group, to facilitate information retrieval and processing. PMID:23458073

Calero, Romel; Mirabal, Mayelin; Bouza, Jesús; Guzmán, María V; Carrillo, Humberto; López, Yamilé; Norazmi, Mohd Nor; Sarmiento, Maria E; Acosta, Armando

2013-01-01

381

Muon probing in optimal and under- doped GdBCO  

NASA Astrophysics Data System (ADS)

By means of MaxEnt-Burg, transverse-field (TF) ?SR data of underdoped (?1; Tc = 81 K) and optimal doped (?0; Tc = 93 K) GdBa2Cu3O7-? (GdBCO) are analyzed. Site search studies for RBCO generated plausible candidates for muon sites [1] called the Balmer and Lin sites. We wish to confirm the muon-probe sites in GdBCO. One of the two Balmer sites and the Lin site are located near O vacancies. These two sites become unstable in underdoped GdBCO(?1). Positive muons are repelled by the positive O vacancies. This repulsion effects would be more pronounced as temperature increases. At 120 K, three signals are present in GdBCO(?1), while at roomtemperature (RT), only one dominant signal remains. In contrast, three signals occur at 120 K and RT for GdBCO(?0), which has much less O vacancies. These results support earlier studies [1] of muon-O sites. Thus, the muons probe away from the CuO2 plane, allowing ?SR to detect magnetic fields originating from potential loop currents in these planes. [2] By ME-?SR analysis, the Balmer & Lin sites in GdBCO are confirmed. Research supported by NSF-REU. [0pt] [1] WK Dawson et al, J Appl Phys 64 (1988) 5809 & Hpf Int 63 (1990) 219.[0pt] [2] CM Varma, PRL 83 (1999) 3538; T Songatikamas et al, J Superconductivity and Novel Magn 23 (2010) 793.

Boekema, C.; Sio, H.; Browne, M. C.

2011-03-01

382

Tb/Na tobermorite: Thermal behaviour and high temperature products  

NASA Astrophysics Data System (ADS)

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 3/ m obtaining cell parameters a=9.39199(4) Å and c=6.84041(5) Å. Terbium silicate apatite heated in melted NaF led to Tb 4O 7 crystals.

Garra, Walter; Marchetti, Fabio; Merlino, Stefano

2009-06-01

383

Reaching out to take on TB in Somalia.  

PubMed

Among the many challenges facing populations disrupted by complex emergencies, personal security and food security rank much higher than access to healthcare. However, over time health needs assume increasing importance. Many complex crises occur in settings where the background incidence of TB is already high; social and economic conditions in crises are then highly conducive to amplification of the existing TB problem. Innovative approaches to delivery of diagnostic and treatment services, transition planning and integration with other healthcare providers and services are vital. In the extremely challenging environment of Somalia, multiple partners are making headway though collaboration and innovation. PMID:24306131

Moore, David A J; Granat, Simo M

2014-01-01

384

Electronic properties of a distorted kagome lattice antiferromagnet Dy3Ru4Al12  

NASA Astrophysics Data System (ADS)

Electronic properties of Dy3Ru4Al12 (hexagonal crystal structure, Dy atoms form distorted kagome nets) are studied on a single crystal by means of magnetization, neutron diffraction, specific heat, and resistivity measurements. The onset of a long-range magnetic order of Dy moments occurs at 7 K through a first-order phase transition. The compound has a noncollinear antiferromagnetic structure with a propagation vector (1/2 0 1/2). The configuration of the Dy moments is consistent with the monoclinic Shubnikov group Cc2/c. The ? coefficient in the temperature linear term of the specific heat is strongly enhanced to 500 mJ mol-1 K-2 taking into account the localized nature of Dy magnetism. An additional contribution originates from spin fluctuations induced in the 4d subsystem of Ru by the exchange field acting from the Dy 4f moments. In an applied magnetic field Dy3Ru4Al12 displays magnetization jumps along all crystallographic directions. All the metamagnetic transitions are accompanied by large positive magnetoresistance. The maximum effect (125%-140%) is attained for current along the [100] axis and field along the [120] or [001] axes. The large positive effect is explained by changes in the conduction electron spectra through the jumps as the conduction electrons interact with localized magnetic moments.

Gorbunov, D. I.; Henriques, M. S.; Andreev, A. V.; Gukasov, A.; Pet?í?ek, V.; Baranov, N. V.; Skourski, Y.; Eigner, V.; Paukov, M.; Prokleška, J.; Gonçalves, A. P.

2014-09-01

385

Enantioselective self-assembly of triangular dy3 clusters with single-molecule magnet behavior.  

PubMed

Three pairs of enantiopure chiral triangular Ln3 clusters, [Ln3 LRRRRRR/SSSSSS (?3 -OH)2 (H2 O)2 (SCN)4 ]?xCH3 OH?yH2 O (R-Dy3 , Ln=Dy, x=6, y=0; S-Dy3 , Ln=Dy, x=6, y=1; R-Ho3 , Ln=Ho, x=6, y=1; S-Ho3 , Ln=Ho, x=6, y=1; R-Er3 , Ln=Er, x=6, y=0; S-Er3 , Ln=Er, x=6, y=1), have been successfully synthesized by a rational enantioselective synthetic strategy. The core of triangular Ln3 is bound in the central N6 O3 of the macrocyclic ligand, and the coordination spheres of Ln ions are completed by four SCN(-) anions and two H2 O molecules in axial positions of the macrocycle. The circular dichroism (CD) and vibrational circular dichroism (VCD) spectra of the enantiomers demonstrate that the chirality is successfully transferred from the ligands to the resulting Ln3 clusters. Ac susceptibility measurements reveal that single-molecule magnet behavior occurs for both enantiopure clusters of R-Dy3 and S-Dy3 . This work is one of the few examples of the successful design of a pair of triangular Dy3 clusters showing simultaneously slow magnetic relaxation and optical activity, and this might open up new opportunities to develop novel multifunctional materials. PMID:25234668

Lin, Shuang-Yan; Wang, Chao; Zhao, Lang; Tang, Jinkui

2014-12-01

386

Optical properties and generation of white light in Dy3+-doped lead phosphate glasses  

NASA Astrophysics Data System (ADS)

Dy3+-doped lead phosphate (PbPKANDy: P2O5+K2O+Al2O3+PbO+Na2O+Dy2O3) glasses were prepared by melt quenching technique and their optical properties have been studied. Judd-Ofelt parameters have been evaluated for 1.0 mol% Dy2O3-doped lead phosphate glass and inturn derived radiative properties for excited luminescent levels of Dy3+ ions. The yellow-to-blue emission intensity ratios and CIE chromaticity coordinates were calculated which have been used to evaluate white light emission as a function of the activator (Dy3+) ion concentration. The observed non-exponential decay nature and quenching of lifetime for higher Dy3+ ion concentration (?1.0 mol%) have been attributed due to energy transfer of dipole-dipole type between excited and unexcited Dy3+ ions. The PbPKANDy glasses exhibit better luminescence properties which are suitable for generation of white light.

Linganna, K.; Rao, Ch. Srinivasa; Jayasankar, C. K.

2013-03-01

387

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

PubMed

The use of thermographic phosphors for high-temperature (>1000??K) thermometry currently is limited by loss of signal due to thermal quenching. This work demonstrates a new phosphor generated by substituting tetrahedral site Al3+-O2- in YAG:Dy with B3+-N3- to produce YABNG:Dy. Conventional YAG:Dy and YABNG:Dy phosphors were synthesized using identical solgel synthesis techniques. X-ray diffraction measurements showed that both had nearly pure crystalline phases, with a minor secondary yttrium-aluminum-monoclinic (YAM) phase present in the YABNG:Dy. The YABNG:Dy sample had a larger and more spherical primary grain than did the YAG:Dy in scanning electron microscopy images. Tests of the thermal response showed that the YABNG:Dy had much stronger phosphorescence emissions than did YAG:Dy, likely due to the morphological differences. Furthermore, the onset of thermal quenching was delayed by approximately 100 K for YABGN:Dy compared to YAG:Dy, and the rate of signal decrease with temperature was reduced. This resulted in greater signal-to-noise ratios and less uncertainty in the temperature measurements, particularly at high temperatures. PMID:25361305

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

2014-11-01

388

ANALYSIS OF THE ELECTRON EXCITATION SPECTRA IN HEAVY RARE EARTH METALS, HYDRIDES AND OXIDES  

E-print Network

397 ANALYSIS OF THE ELECTRON EXCITATION SPECTRA IN HEAVY RARE EARTH METALS, HYDRIDES AND OXIDES C thin evaporated foils of heavy rare earths (Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) in three different chemical of high energy incident electrons (75 keV) transmitted through thin foils of yttric rare earth elements

Boyer, Edmond

389

Lightweight high performance ceramic material  

DOEpatents

A sintered ceramic composition includes at least 50 wt. % boron carbide and at least 0.01 wt. % of at least one element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy Ho, Er, Tm, Yb, and Lu, the sintered ceramic composition being characterized by a density of at least 90% of theoretical density.

Nunn, Stephen D [Knoxville, TN

2008-09-02

390

Correlation between volatility of rare-earth metals and encapsulation of their carbides in carbon nanocapsules  

Microsoft Academic Search

Encapsulation of metals in multilayered graphitic capsules has been studied for all the rare-earth elements (Sc, Y, and Ln = La, Ce, ..., Lu) excluding Pm by using electric arc discharge. Electron microscopy and X-ray diffraction of carbonaceous products revealed that most of rare-earth metals (Sc, Y, La, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er, and Lu) were encapsulated

Yahachi Saito; Mitsumasa Okuda; Tadanobu Yoshikawa; Atsuo Kasuya; Yuichiro Nishina

1994-01-01

391

Rare earth metal oxides: formation, characterization and catalytic activity Thermoanalytical and applied pyrolysis review  

Microsoft Academic Search

This review provides a guide to the recent literature on the characterization of the decomposition routes of different precursors, especially carboxylates of rare earth metals (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y and Th), and the formation of the final oxide products. It also discusses the effects of 1.(1) the nature of

Gamal A. M. Hussein

1996-01-01

392

Point-defect properties in HCP rare earth metals with analytic modified embedded atom potentials  

Microsoft Academic Search

The analytic embedded atom method (EAM) type many-body potentials of hcp rare earth metals (Dy, Er, Gd, Ho, Nd, Pr, and Tb) have been constructed. The hcp lattice is shown to be energetically most stable when compared with the fcc and bcc structure, and the hcp lattice with ideal c\\/a. The mechanical stability of the corresponding hcp lattice with respect

Wangyu Hu; Huiqiu Deng; Xiaojian Yuan; Masahiro Fukumoto

2003-01-01

393

Extraction of Rare-Earth Elements from Nitric Acid Solutions with Bidentate Phosphoryl-containing Compounds and Their Mixtures  

Microsoft Academic Search

Extraction of microamounts of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu from HNO3 solutions with neutral bidentate phosphoryl-containing compounds was studied. Extraction with tetraphenylmethylenediphosphine dioxide increases in going from Lu to La, and extraction with methyleneoxyphenyldiphosphine dioxides increases in the opposite direction. The anomalous aryl strengthening effect varies in the same direction.

A. N. Turanov; V. K. Karandashev; V. E. Baulin

2001-01-01

394

Scientific and Technological Issues Related to Rare Earth Oxides: An Introduction  

E-print Network

of the Periodic Table (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) with atomic numbers from 57 of di-, tri-, and tetravalent RE elements and the RE­O bond lengths are summarized in Table 1 summarized in Table 2 for the oxides of the dominant trivalent RE elements. The RE atomic radii indeed

Svane, Axel Torstein

395

Role of the Dzyaloshinskii-Moriya interaction in multiferroic perovskites I. A. Sergienko and E. Dagotto  

E-print Network

Role of the Dzyaloshinskii-Moriya interaction in multiferroic perovskites I. A. Sergienko and E; published 23 March 2006 With the perovskite multiferroic RMnO3 R=Gd,Tb,Dy as guidance, we argue-Teller, and DMI terms. The phase diagram contains a multiferroic phase between A and E antiferromagnetic phases

Tennessee, University of

396

Host dependence of spectroscopic properties of Dy 3+ - doped and Dy 3+, Tm 3+ -codped Ge-Ga-S-CdI 2 chalcohalide glasses.  

PubMed

Two serial Dy(3+)-doped and Dy(3+), Tm(3+)-codoped (100-x)(0.8GeS(2).0.2Ga(2)S(3)).xCdI(2) (0Dy(3+)-doped glasses, increase of CdI(2) had positive effect up to 1330 nm fluorescence and the emission cross section (sigma emi) was estimated to be 4.19 x 10(-20)cm(2) for the 0.2 wt% Dy(3+)-doped 64 GeS(2).16 Ga(2)S(3).20 CdI(2) glass. In the Dy(3+), Tm(3+)-codoped glasses, increase of CdI(2) diminished the amount of ethane-like units [S(3)(Ga)Ge-Ge(Ga)S(3)], improved the Tm(3+): 3F 4-->Dy(3+): 6H 11/2 energy transfer efficiency and intensified the mid-infrared emissions. The emission cross sections (sigma emi) of the 2900 and 4300 nm fluorescences were estimated to be 1.68 x 10(-20) and 1.20 x 10(-20)cm(2) respectively for the 0.2 wt% Dy(3+) and 0.5 wt% Tm(3+) codoped 64 GeS(2).16 Ga(2)S(3).20 CdI(2) glass. These novel chalcohalide glasses are promising candidate materials for fiber-amplifiers and mid-infrared laser devices. PMID:19688013

Guo, Haitao; Liu, Lei; Wang, Yongqian; Hou, Chaoqi; Li, Weinan; Lu, Min; Zou, Kuaisheng; Peng, Bo

2009-08-17

397

Stellar neutron capture cross sections of the Gd isotopes  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 152Gd, 154Gd, 155Gd, 156Gd, 157Gd, and 158Gd were measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p,n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? Barium Fluoride Detector, which was improved by replacing crystals with high ? background and by introducing a pierced crystal at zero degrees with respect to the beam axis. These changes resulted in a significantly increased efficiency for capture events. The main experimental problem was that the samples of the two s isotopes 152Gd and 154Gd showed only relatively low enrichment. Nevertheless, the spectroscopic quality of the BaF2 detector allowed evaluation of the corresponding corrections for isotopic impurities reliably. The cross section ratios could be determined with an overall uncertainty of typically 1%, an improvement by factors of five to ten compared to existing data. Severe discrepancies were found with respect to previous results. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT=10 keV and 100 keV. The new stellar cross sections were used for an updated analysis of the s-process reaction flow in the mass region between samarium and gadolinium, which is characterized by branchings at 151Sm, 154Eu, and 155Eu. With the classical approach, the s-process temperature could be constrained corresponding to a range of thermal energies between kT=28 and 33 keV. The 152Gd production in low mass stars was found to depend strongly on the neutron freeze-out at the end of the helium shell burning episodes.

Wisshak, K.; Voss, F.; Käppeler, F.; Guber, K.; Kazakov, L.; Kornilov, N.; Uhl, M.; Reffo, G.

1995-11-01

398

Stellar neutron capture cross sections of the Gd isotopes.  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 152Gd, 154Gd, 155Gd, 156Gd, 157Gd, and 158Gd were measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p, n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? Barium Fluoride Detector The main experimental problem was that the samples of the two s-only isotopes 152Gd and 154Gd showed only relatively low enrichment, but the spectroscopic quality of the BaF2 detector allowed to determine the resulting corrections for isotopic impurities reliably. The cross section ratios could be determined with an overall uncertainty of typically 1%, an improvement by factors of five to ten compared to existing data. Severe discrepancies were found with respect to previous results. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT = 10 keV and 100 keV. The new stellar cross sections were used for an updated analysis of the s-process reaction flow in the mass region between samarium and gadolinium, which is characterized by branchings at 151Sm, 154Eu, and 155Eu. With the classical approach, the s-process temperature could be constrained corresponding to a range of thermal energies between kT - 28 keV and 33 keV. The 152Gd production in low mass stars was found to depend strongly on the neutron freeze-out at the end of the helium shell burning episodes.

Wisshak, K.; Voss, F.; Käppeler, F.; Guber, K.; Kazakov, L.; Kornilov, N.; Uhl, M.; Reffo, G.

1995-05-01

399

Development of YAG:Dy Thermographic Phosphor Coatings for Turbine Engine Applications  

NASA Technical Reports Server (NTRS)

The selection and development of thermographic phosphor coatings were pursued to meet the objective of demonstrating luminescence-decay-based temperature measurements up to 1300C on the surface of a vane in an operating demonstrator turbine engine. To meet this objective, YAG:Dy was selected based on the desirable luminescence performance observed for YAG:Dy powder: (1) excellent temperature sensitivity and intensity at operating turbine engine temperatures, (2) an emission peak at the relatively short wavelength of 456 nm, where the interference from background blackbody radiation is fairly low, and (3) its nearly single exponential decay which makes for a simple, reliable temperature calibration. However, implementation of YAG:Dy for surface temperature measurements required application of YAG:Dy as a coating onto the surface of a superalloy component with a preexisting yttria-stabilized zirconia (YSZ) thermal barrier coating (TBC). An inherent dilemma in producing a YAG:Dy coating is that coating processing is constrained to be performed at temperatures below (less than 1200C) what is considered safe for the superalloy component, much lower than temperatures used to produce the high quality crystalline powder. Therefore, YAG:Dy coatings tend to exhibit lower luminescence performance compared to well prepared YAG:Dy powder, and the luminescence performance of the coating will depend on the method of coating deposition. In this presentation, the luminescence performance of YAG:Dy coatings prepared by the different methods of (1) application of a binder-based YAG:Dy-containing paint, (2) solution precursor plasma spray (SPPS), and (3) electron-beam physical vapor deposition (EB-PVD) and the effect of post-deposition heat treatments will be discussed.

Eldridge, J. I.; Jenkins, T. P.; Allison, S. W.; Wolfe, D. E.; Jordan, E. H.

2012-01-01

400

Bovine gd T-Cell Responses to the Intracellular Protozoan Parasite Theileria parva  

Microsoft Academic Search

T cells bearing the gd antigen receptor (gd T cells) can constitute up to 50% of T cells in the peripheral blood and lymphoid organs of young cattle. We present data showing that gd T cells are involved in immune responses against Theileria parva. gd T cells isolated from peripheral blood mononuclear cells (PBMC) of T. parva-naive and -immune cattle

CLAUDIA A. DAUBENBERGER; EVANS L. N. TARACHA; LAIMA GAIDULIS; WILLIAM C. DAVIS; DECLAN J. MCKEEVER

1999-01-01

401

Photoinduced phenomena in azo-dyed gelatine films  

NASA Astrophysics Data System (ADS)

In this work a photoinduced properties of azo-dye doped gelatine films were studied. Gelatine is the oldest polymeric matrix, which is used in holography and photography. Preparation of these films is simple and cheap, but ingredients aren't toxic. Films were synthesized using gelatine and azo-dye -Disperse Red13. Non- aqueous solvents - dimethyl sulfoxide and acetic acid, were used. Films were coated on glass plates using applicator with layer thickness 30, 60, 90 ?m and then were heated in vacuum chamber. Azo-dyed gelatine films were illuminated by 532nm laser radiation. Photoinduced birefringence and photoinduced dichroism dependence on films ingredients ratio, laser light intensity and sample treatment temperature were investigated. Holographic recording on these films was performed in dependence on recording beam intensity and polarization. Volume polarization gratings and direct surface relief formation were studied by measuring diffraction efficiency with 660nm diode laser radiation. The obtained surface relief was investigated by AFM.

Aleksejeva, J.; Teteris, J.

2012-08-01

402

Structure and emissive properties of heterobimetallic Ln-Au coordination polymers: role of Tb and Eu in non-aurophilic [nBu4N]2[Ln(NO3)4Au(CN)2] versus aurophilic Ln[Au(CN)2]3·3H2O/3D2O chains.  

PubMed

This investigation is focused on comparing photophysical properties between two series of lanthanide-dicyanoaurate coordination polymers that contain and lack aurophilic interactions, respectively. Luminescence and crystallographic studies have been carried out on five different coordination polymer chain frameworks: the non-aurophilic [(n)Bu4N]2[LnxGd1-x(NO3)4Au(CN)2] (Ln = Eu, Tb; x = 0.01, 0.02, 0.04, 0.08) and[(n)Bu4N]2[EuxTb1-x(NO3)4Au(CN)2] (x = 0.25, 0.5, 0.75), as well as the analogous solid-solutions of aurophilic LnxGd1-x[Au(CN)2]3·3H2O and EuxTb1-x[Au(CN)2]3·3H2O. The single-crystal structures of M[Au(CN)2]3 ·3H2O (M = Eu, Gd) are also reported for comparison. In the aurophilic frameworks the close proximity of gold(I) centers on neighboring chains allows for Au-Au interactions to take place that facilitate energy transfer between lanthanides. Terbium- and europium-doped aurophilic frameworks show energy transfer between one of the lanthanide ions and dicyanoaurate centers as observed via luminescence measurements. In the non-aurophilic frameworks the [(n)Bu4N] cations separate the Au-Au chains, thereby preventing interaction between them, and preventing energy transfer. By preparing the aurophilic EuxTb1-x[Au(CN)2]3·3D2O frameworks, it was shown that the O-H vibrational energy in the hydrated (aurophilic) samples can partially quench the Ln signal. PMID:24968022

Ahern, John C; Roberts, Ryan J; Follansbee, Philip; McLaughlin, Jeffrey; Leznoff, Daniel B; Patterson, Howard H

2014-07-21

403

"I Can Also Serve as an Inspiration": A Qualitative Study of the TB&Me Blogging Experience and Its Role in MDR-TB Treatment  

PubMed Central

Background In 2011, Médecins Sans Frontières (MSF) established a blogging project, “TB&Me,” to enable patients with multidrug-resistant tuberculosis (MDR-TB) to share their experiences. By September 2012, 13 MDR-TB patients had blogged, either directly or with assistance, from the UK, Australia, Philippines, Swaziland, Central African Republic, Uganda, South Africa, India, and Armenia. Due to the lack of research on the potential for social media to support MDR-TB treatment and the innovative nature of the blog, we decided to conduct a qualitative study to examine patient and staff experiences. Our aim was to identify potential risks and benefits associated with blogging to enable us to determine whether social media had a role to play in supporting patients with MDR-TB. Methods and Findings Participants were identified and selected purposively. TB&Me bloggers, project staff, MSF headquarters staff involved with TB and WHO European Region TB policy advisors were invited to participate in a semi-structured interview. Twenty interviews were conducted (five with bloggers). Data analysis drew upon principles of grounded theory, with constant comparison of data, cases and categories, and attention to deviant cases. We found that the TB&Me blog was associated with identified health benefits, with no reported instances of harm. There were three main findings: blogging was reported as useful for adherence to DR-TB treatment and supportive of the treatment-taking process by all bloggers and project staff; blogging provided support to patients (peer support, shared experience and reduction in isolation); and the blog was perceived as giving patients strength and voice. Conclusion The TB&Me blog was seen to be associated with positive identified health and emotional benefits. Component 5 of the Stop TB Global Plan highlights the importance of empowering TB patients and communities. Blogging could be a useful tool to help achieve that ambition. PMID:25251404

Horter, Shona; Stringer, Beverley; Venis, Sarah; du Cros, Philipp

2014-01-01

404

Microstructure and rolling capability of modified AZ31-Ce-Gd alloys  

SciTech Connect

AZ31-Ce-Gd alloys were studied and the influence of cerium (Ce) and gadolinium (Gd) on the microstructure and rolling capability of AZ31 alloy was investigated. The results indicated that the grains of AZ31 alloy were refined with Ce and Gd addition. Ce and Gd addition resulted in the formation of Al{sub 4}Ce, Al{sub 2}Gd and Mg{sub 3}Gd. After homogenization and rolling, the Al{sub 4}Ce, Al{sub 2}Gd and Mg{sub 3}Gd still existed. The rolling capability of AZ31 alloy was improved obviously with Ce and Gd addition. However, once Gd content increased to a certain value, the rolling capability of the modified alloy declined but still better than that of AZ31 alloy.

Li Wenping [Key Laboratory of Automobile Materials of Ministry of Education and Department of Materials Science and Engineering, Nanling Campus of Jilin University, No.5988 Renmin Street, Changchun 130025 (China); Zhou Hong, E-mail: asnacml@163.com [Key Laboratory of Automobile Materials of Ministry of Education and Department of Materials Science and Engineering, Nanling Campus of Jilin University, No.5988 Renmin Street, Changchun 130025 (China); Lin Pengyu; Zhao Shizhe [Key Laboratory of Automobile Materials of Ministry of Education and Department of Materials Science and Engineering, Nanling Campus of Jilin University, No.5988 Renmin Street, Changchun 130025 (China)

2009-11-15

405

HIV testing and disclosure: a qualitative analysis of TB patients in South Africa  

Microsoft Academic Search

In South Africa, more than 60% of TB patients have HIV co-infection. Voluntary counseling and testing (VCT) is critical to effective HIV prevention, and TB facilities are optimal venues for delivery of these services. This study employed qualitative research methods to explore the decision-making processes for HIV testing and serostatus disclosure by 21 patients hospitalized with multi\\/extensively-drug resistant TB (M\\/XDR-TB)

A. Daftary; N. Padayatchi; M. Padilla

2007-01-01

406

Size and Usage Patterns of Private TB Drug Markets in the High Burden Countries  

Microsoft Academic Search

BackgroundTuberculosis (TB) control is considered primarily a public health concern, and private sector TB treatment has attracted less attention. Thus, the size and characteristics of private sector TB drug sales remain largely unknown.Methodology\\/Principal FindingsWe used IMS Health data to analyze private TB drug consumption in 10 high burden countries (HBCs), after first mapping how well IMS data coverage overlapped with

William A. Wells; Colin Fan Ge; Nitin Patel; Teresa Oh; Elizabeth Gardiner; Michael E. Kimerling; Abdisalan Mohamed Noor

2011-01-01

407

A Threshold Value for the Time Delay to TB Diagnosis  

PubMed Central

Background In many communities where TB occurs at high incidence, the major force driving the epidemic is transmission. It is plausible that the typical long delay from the onset of infectious disease to diagnosis and commencement of treatment is almost certainly the major factor contributing to the high rate of transmission. Methodology/Principal Findings This study is confined to communities which are epidemiologically relatively isolated and which have low HIV incidence. The consequences of delays to diagnosis are analyzed and the existence of a threshold delay value is demonstrated. It is shown that unless a sufficient number of cases are detected before this threshold, the epidemic will escalate. The method used for the analysis avoids the standard computer integration of systems of differential equations since the intention is to present a line of reasoning that reveals the essential dynamics of an epidemic in an intuitively clear way that is nevertheless quantitatively realistic. Conclusions/Significance The analysis presented here shows that typical delays to diagnosis present a major obstacle to the control of a TB epidemic. Control can be achieved by optimizing the rapid identification of TB cases together with measures to increase the threshold value. A calculated and aggressive program is therefore necessary in order to bring about a reduction in the prevalence of TB in a community by decreasing the time to diagnosis in all its ramifications. Intervention strategies to increase the threshold value relative to the time to diagnosis and which thereby decrease disease incidence are discussed. PMID:17712405

Uys, Pieter W.; Warren, Robin M.; van Helden, Paul D.

2007-01-01

408

Thrombin Kits TB188 8/98 Novagen 1  

E-print Network

Thrombin Kits TB188 8/98 Novagen 1 Orders: 800 526-7319 Technical Service: 800 207-0144 Table .......................................................................................2 Description 2 Components 2 Thrombin Cleavage ................................................................................3 Small scale optimization 3 Scale-up 4 Factors that affect thrombin activity 4 Monitoring cleavage

Lebendiker, Mario

409

ANL/APS/TB-5 Functional Description of APS Beamline  

E-print Network

ANL/APS/TB-5 Functional Description of APS Beamline Front Ends by Tuncer Kuzay February 1993 Advanced Photon Source & Argonne National Laboratory, Argonne, Illinois 60439 o operated by The University Avenue Argonne, llUnms 60439 AN/APSflB-5 Functional Description of APS Beamline Front Ends by Tuncer

Kemner, Ken

410

Understanding TB latency using computational and dynamic modelling procedures.  

PubMed

The Mycobacterium tuberculosis bacilli's potency to cause persistent latent infection that is unresponsive to the current cocktail of TB drugs is strongly associated with its ability to adapt to changing intracellular environments, and tolerating, evading and subverting host defence mechanisms. We applied a combination of bioinformatics and mathematical modelling methods to enhance the understanding of TB latency dynamics. Analysis of time course microarray gene expression data was carried out and gene profiles for bacilli adaptation and survival in latency, simulated by hypoxia were determined. Reverse network engineering techniques were used to predict gene dependencies and regulatory interactions. Biochemical systems theory was applied to mathematically model the inferred gene regulatory networks. Significant regulatory genes involved in latency were determined by a combination of systems biology procedures and mathematical modelling of the inferred regulatory networks. Analysis of gene clusters of the inferred networks in the stationary and non-replicating phases of the bacilli predicted probable functions of some of the latency genes to be associated with latency genes of known functions. The systems biology approach and mathematical computational deletion experiments predicted key genes in the TB latency/dormancy program that may be possible TB drug targets. However, these gene candidates require experimental testing and validation. PMID:23146828

Magombedze, Gesham; Mulder, Nicola

2013-01-01

411

Neutron Studies of Tb2Mo2O7  

SciTech Connect

We have used the new high energy resolution spectrometer (BaSiS), at the Spallation Neutron Source in Oak Ridge, to conclusively prove the existence of a low energy mode at 0.34(1) meV in the spin glass Tb{sub 2}Mo{sub 2}O{sub 7}. This mode is reminiscent of the excitation observed in the ordered phases of both Tb{sub 2}Ti{sub 2}O{sub 7} and Tb{sub 2}Sn{sub 2}O{sub 7}. The dynamical nature of the transition seen in the magnetization at {approx} 25 K suggests that this frustrated magnet shows a dynamic crossover between a high-temperature phase of poorly correlated, quickly relaxing spins to a low-temperature regime with much slower, short ranged spin correlations extending no further than to the next nearest neighbor. Existing theories explain the spin glass transition in terms of a phase transition and order parameters, and assume the existence of a distinct spin glass phase. There is no evidence for such a phase in Tb{sub 2}Mo{sub 2}O{sub 7}.

Gardner, Jason [Indiana University; Ehlers, Georg [ORNL; Diallo, Souleymane Omar [Oak Ridge National Laboratory (ORNL)

2012-01-01

412

Predicting Efficient Antenna Ligands for Tb(III) Emission  

SciTech Connect

A series of highly luminescent Tb(III) complexes of para-substituted 2-hydroxyisophthalamide ligands (5LI-IAM-X) has been prepared (X = H, CH{sub 3}, (C=O)NHCH{sub 3}, SO{sub 3}{sup -}, NO{sub 2}, OCH{sub 3}, F, Cl, Br) to probe the effect of substituting the isophthalamide ring on ligand and Tb(III) emission in order to establish a method for predicting the effects of chromophore modification on Tb(III) luminescence. The energies of the ligand singlet and triplet excited states are found to increase linearly with the {pi}-withdrawing ability of the substituent. The experimental results are supported by time-dependent density functional theory (TD-DFT) calculations performed on model systems, which predict ligand singlet and triplet energies within {approx}5% of the experimental values. The quantum yield ({Phi}) values of the Tb(III) complex increases with the triplet energy of the ligand, which is in part due to the decreased non-radiative deactivation caused by thermal repopulation of the triplet. Together, the experimental and theoretical results serve as a predictive tool that can be used to guide the synthesis of ligands used to sensitize lanthanide luminescence.

Samuel, Amanda P.S.; Xu, Jide; Raymond, Kenneth

2008-10-06

413

Anti-TB activity of Evodia elleryana bark extract  

PubMed Central

An ethyl acetate extract of bark from Evodia elleryana produced significant growth inhibition of Mycobacterium tuberculosis at concentrations only minimally inhibitory to human T cells. The crude extract yielded 95% inhibition of TB at 50 ?g/ml. The crude extract yielded 29 % growth inhibition of human T-cells in culture at that concentration. PMID:17350179

Barrows, Louis R.; Powan, Emma; Pond, Christopher D.; Matainaho, Teatulohi

2009-01-01

414

Can IMA-RNTCP stop TB by 2050?  

PubMed

Tuberculosis has been with mankind since time immemorial. No other disease has so much sociological, economic and health significance as tuberculosis. In the poorly functioning tuberculosis control programme, the ratio of incidence to prevalence may be as high as 1: 3.5. Experience and observations from both developed and developing countries have demonstrated that if case detection and cure rates in smear positive cases are consistently achieved to 70 % and 85 % respectively, the incidence would decline to 5% annually while prevalence decline very rapidly, being reduced to less than half of its previous level within three years. Since RNTCP India is based on scientific principles of DOTS strategy, its effective clinical and public health management, committed and co-ordinated efforts of public and private partners (IMA) would certainly lead to decline the prevalence (already declined from 586/1,00,000 in 1990 to 185/1,00,000 population in 2008 - 68 % reduction), mortality rate from 42/ 1,00,000 in 1990 to 21/1,00,000 in 2015 (already reduced to 24/1,00,000 in 2008 - 43 % reduction) as target set under indicator 23 of TB-related Millennium Development Goal. This kind of impact would result in halting and reversing TB Incidence to pave way for future effective control of TB, which may not remain a public health problem by 2050. Thus, TB control is a winnable battle. PMID:22482323