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1

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

NASA Astrophysics Data System (ADS)

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

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

2003-04-01

2

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

3

Structural chemistry and physical properties of ternary compounds R 6Ni 15As 10, R = Y, Sm, Gd, Tb, Dy  

Microsoft Academic Search

The ternary rare-earth nickel arsenides R6Ni15As10 (R=Y, Sm, Gd, Tb, Dy) were synthesized from the elements by reaction at elevated temperatures. They were found to crystallize with a hexagonal structure which was determined from single-crystal X-ray data in case of Tb6Ni15As10, space group P63\\/m, Z=2, a=17.005(1) and c=3.8877(2). The crystal structure for the isostructural compound Gd6Ni15As10 has been determined using

Volodymyr Babizhetskyy; Kurt Hiebl; Arndt Simon

2006-01-01

4

Crystallographic and magnetic properties of the hydrides ? (R = Y, Ce, Nd, Sm, Gd, Tb, and Dy)  

NASA Astrophysics Data System (ADS)

A systematic study of the structural and intrinsic magnetic properties of the hydrides 0953-8984/10/31/019/img9 (R = Y, Ce, Nd, Sm, Gd, Tb, and Dy) has been performed. Hydrogenation leads to a relative volume expansion of the unit cell and a decrease in x-ray density for each compound. Anisotropic expansions mainly along the a- and b-axes rather than along the c-axis for all of the compounds upon hydrogenation are observed. The lattice constants and the unit-cell volume of 0953-8984/10/31/019/img10 and 0953-8984/10/31/019/img9 decrease with increasing R atomic number from Nd to Dy, except for Ce, reflecting the lanthanide contraction. Hydrogenation results in an increase in the Curie temperature and a corresponding increase in the saturation magnetization at room temperature for each compound. After hydrogenation a decrease of 0953-8984/10/31/019/img12 in the average Fe atomic magnetic moment and a slight increase in the anisotropy field for 0953-8984/10/31/019/img13 are achieved at 4.2 K. First-order magnetization processes (FOMP) occur in magnetic fields of around 1.5 T and 4.0 T at 4.2 K for 0953-8984/10/31/019/img14 and 0953-8984/10/31/019/img15, and around 1.4 T at room temperature for 0953-8984/10/31/019/img16. The abnormal crystallographic and magnetic properties of 0953-8984/10/31/019/img17 and 0953-8984/10/31/019/img18 suggest that the Ce ion is non-triply ionized.

Han, Xiu-Feng; Xu, Ren-Geng; Wang, Xin-Hua; Pan, H. G.; Miyazaki, T.; Baggio-Saitovitch, E.; Yang, F. M.; Cheng, C. P.

1998-08-01

5

Electrical and Hall Resistivity in Rare Earth Intermetallic Compounds RAg1-xInx (R: Gd, Tb and Dy)  

NASA Astrophysics Data System (ADS)

The electrical resistivity and the Hall resistivity in polycrystalline specimens of RAg1-xInx have been measured from 4.2 K to room temperature and the paramagnetic region up to room temperature, respectively. The spin disorder resistivity at 0 K, ?m(0), takes a maximum near the boundary of the different magnetic structures in each compound system, and that above the Curie temperature, ?m(?), increases with x in Gd system, while it takes a maximum around x{=}0.3 in Tb and Dy systems. The ordinary Hall coefficient, R0, is positive for all the compounds. On the other hand, the spontaneous Hall coefficient, Rs, is negative for all the compounds except GdAg and TbAg and its magnitude increases with x for x?0.1 in all the systems. The results have been discussed on the basis of the localized spin model.

Yagasaki, Katsuma; Fujii, Hironobu; Fujiwara, Hiroshi; Okamoto, Tetsuhiko

1980-07-01

6

The local atomic structure of RMgZn (R=Y, Gd, Dy and Tb)  

Microsoft Academic Search

The rare earth element in the RMgZn system provides a unique probe of the atomic structure of a face-centered icosahedral (fci) quasicrystal (qc). Unlike many of the other ternary and higher component qc systems, the compound around R8Mg42Zn50 allows for the substitution of one of its main components (R=Y, Er, Ho, Dy and Tb) without any appreciable change in its

M. J Kramer; S. T Hong; P. C Canfield; I. R Fisher; J. D Corbett; Y Zhu; A. I Goldman

2002-01-01

7

Magnetic and microstructural properties of (Nd,Pr)-(Tb,Dy,Gd)-(Fe,Co,Al,Cu)-B type magnets  

NASA Astrophysics Data System (ADS)

(Nd,Pr)-(Tb,Dy,Gd)-(Fe,Co,Al,Cu)-B magnets were heat treated in two different ways and investigated in the temperature range 4.2 to 400 K. After optimal heat treatment intrinsic coercive field i H c = 1640 and 5040 kA/m for room temperature and 10 K was obtained and the temperature coefficient of remanence ? = -0.01 for temperature range 80 to 375 K was found. On basis of magnetic measurements and 57Fe Mssbauer spectroscopy, the possible reasons for the increase of i H c during multi-step heat treatment are discussed.

Arinicheva, O. A.; Lileev, A. S.; Reissner, M.; Lukin, A. A.; Starikova, A. S.

2013-04-01

8

Nuclear quadrupole interaction studies of C15 RMn{sub 2} hydrides (R=Y,Gd,Tb,Dy)  

SciTech Connect

The nuclear electric quadrupole interaction (QI) of the probe nucleus {sup 111}In/{sup 111}Cd in the paramagnetic phase of the C15 rare earth (R)-manganese hydrides (deuterides) RMn{sub 2}H(D){sub x}, with R=Y, Gd, Tb, and Dy, has been investigated by perturbed angular-correlation spectroscopy. The QI between the {sup 111}Cd 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 TbMn{sub 2}H(D){sub x} in the concentration range 0{<=}x{<=}4.3 and in RMn{sub 2}H(D){sub x}, R=Y,Gd,Dy at the highest H content of x{approx}4.3. The relative temperature dependence of the EFG in the parent compounds RMn{sub 2} is twice as strong as in isostructural RAl{sub 2} which can be related to differences in the Debye temperatures resulting from different radius ratios r{sub R}/r{sub Mn} and r{sub R}/r{sub Al}[Joseph-Gschneidner postulate, Scr. Metall.2, 631 (1968)]. Hydrogenation of RMn{sub 2} 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 RMn{sub 2}. These results are compared with the much stronger concentration dependence and the anomalous temperature dependence of the QI of {sup 111}Cd in the C15 hydrides HfV{sub 2}H{sub x}. Evidence for an exceptionally high H mobility in TbMn{sub 2}H{sub x} is presented. The measurements provide information on structural changes and magnetic ordering temperatures at different H concentrat0010io.

Forker, M.; Bedi, S. C. [Helmholtz Institut fuer Strahlen-und Kernphysik, University of Bonn, Nussallee 14-16, D-53115 Bonn (Germany); Euler, H. [Steinmann-Institut fuer Geologie, Mineralogie und Palaeontologie, University of Bonn, Poppelsdorfer Schloss, D-53115 Bonn (Germany)

2008-09-01

9

High-pressure synthesis, electrical and magnetic properties of new filled skutterudites LnOs 4P 12 (Ln = Eu, Gd, Tb, Dy, Ho, Y)  

Microsoft Academic Search

New filled skutteudites LnOs4P12 (Ln: Eu, Gd, Tb, Dy, Ho and Y) have been prepared at high temperatures and at high pressures. X-ray diffraction of these compounds is studied at room temperature. The relationship between lattice constants and atomic numbers of lanthanide (including Y) is obtained for LnOs4P12 (Ln: lanthanide). Electrical and magnetic properties of the new filled skutterudites with

K. Kihou; I. Shirotani; Y. Shimaya; C. Sekine; T. Yagi

2004-01-01

10

Structural and magnetic properties of hydrides R3Fe29- xVxHy (R=Y, Ce, Nd, Sm, Gd, Tb, and Dy)  

NASA Astrophysics Data System (ADS)

A systematic investigation of crystallographic and intrinsic magnetic properties of the hydrides R3Fe29-xVxHy (R=Y, Ce, Nd, Sm, Gd, Tb, and Dy) has been performed in this work. The lattice constants a, b, and c and the unit cell volume of R3Fe29-xVxHy decrease with increasing rare-earth atomic number from Nd to Dy, except for Ce, reflecting the lanthanide contraction. Hydrogenation results in regular anisotropic expansions along the a-, b-, and c-axes in this series of hydrides. Abnormal crystallographic and magnetic properties of Ce3Fe27.5V1.5H6.5, like Ce3Fe27.5V1.5, suggest that the Ce ion is non-triply ionized. Hydrogenation leads to the increase in both Curie temperature for all the compounds and in the saturation magnetization at 4.2 K and RT for R3Fe29-xVx with R=Y, Ce, Nd, Sm, Gd, and Dy, except for Tb. Hydrogenation also leads to a decrease in the anisotropy field at 4.2 K and RT for R3Fe29-xVx with R=Y, Ce, Nd, Gd, Tb, and Dy, except for Sm. The Ce3Fe27.5V1.5 and Gd3Fe28.4V0.6 show the larger storage of hydrogen with y=6.5 and 6.9 in these hydrides.

Han, Xiu-Feng; Xu, Ren-Geng; Wang, Xin-Hua; Pan, H. G.; Baggio-Saitovitch, E.; Miyazaki, T.; Yang, F. M.; Chen, C. P.

1998-12-01

11

Highly uniform and monodisperse GdOF:Ln(3+) (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

2013-09-18

12

Structural relative stabilities and pressure-induced phase transitions for lanthanide trihydrides REH3 (RE=Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu)  

NASA Astrophysics Data System (ADS)

The structures, structural relative stabilities, pressure-induced phase transitions, and equations of state for lanthanide trihydrides REH3 (RE=Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu) are systematically studied using ab initio calculations under a core state model (CSM). The obtained ground-state parameters, such as lattice constants and bulk modulus, agree well with the available data. Among the P63/mm, P3c1, and P63cm structures, the P63cm structure is found to be the most stable structure for lanthanide trihydride via the comparison of the calculated total energies. With the help of BirchMurnaghan equation of state, the structural transitions from hexagonal to cubic for REH3 (RE=Sm, Gd, Ho, Er, and Lu) under pressure are affirmed; especially, the similar behavior of REH3 (RE= Tb, Dy, and Tm) is reasonably predicted for the first time by this means. For the transitions, the repulsive interactions of HH atoms may play an important role in terms of the analysis of the structures in the vicinity of the theoretical phase transition.

Kong, Bo; Zhang, Lin; Chen, Xiang-Rong; Zeng, Ti-Xian; Cai, Ling-Cang

2012-06-01

13

Face-sharing heterotrinuclear M(II)-Ln(III)-M(II) (M = Mn, Fe, Co, Zn; Ln = La, Gd, Tb, Dy) complexes: synthesis, structures, and magnetic properties.  

PubMed

Trinuclear linear 3d-4f-3d complexes (3d = Mn(II), Fe(II), Co(II), Zn(II) and 4f = La(III), Gd(III), Tb(III), Dy(III)) were prepared by using a tripodal nonadentate Schiff base ligand, N,N',N''-tris(2-hydroxy-3-methoxybenzilidene)-2-(aminomethyl)-2-methyl-1,3-propanediamine. The structural determinations showed that in these complexes two distorted trigonal prismatic transition metal complexes of identical chirality are assembled through 4f cations. The Mn and Fe entities crystallize in the chiral space group P2(1)2(1)2(1) as pure enantiomers; the cobalt complexes exhibit a less straightforward behavior. All Mn, Fe, and Co complexes experience M(II)-Ln(III) ferromagnetic interactions. The Mn-Gd interaction is weak (0.08 cm(-1)) in comparison to the Fe-Gd (0.69 cm(-1)) and Co-Gd (0.52 cm(-1)) ones while the single ion zero field splitting (ZFS) term D is larger for the Fe complexes (5.7 cm(-1)) than for the cobalt ones. The cobalt complexes behave as single-molecules magnets (SMMs) with large magnetization hysteresis loops, as a consequence of the particularly slow magnetic relaxation characterizing these trinuclear molecules. Such large hysteresis loops, which are observed for the first time in Co-Ln complexes, confirm that quantum tunnelling of the magnetization does not operate in the Co-Gd-Co complex. PMID:20446714

Yamaguchi, Tomoka; Costes, Jean-Pierre; Kishima, Yukana; Kojima, Masaaki; Sunatsuki, Yukinari; Brfuel, Nicolas; Tuchagues, Jean-Pierre; Vendier, Laure; Wernsdorfer, Wolfgang

2010-10-18

14

Vacuum ultraviolet excited luminescence properties of Ca3Gd7(SiO4)5(PO4)O2:Re3+ (Re3+=Tb3+, Dy3+) phosphors  

NASA Astrophysics Data System (ADS)

A series of Ca3Gd7(SiO4)5(PO4)O2:Re3+ (Re3+=Tb3+, Dy3+) phosphors were synthesized by a solid-state reaction, and their vacuum ultraviolet excitation and emission characteristics were measured. All the excitation spectra show a broad band in the region of 140-210 nm, which can be mainly assigned to the host absorption. For Tb3+-doped sample, the absorption bands at 230 nm and 281 nm are respectively ascribed to the f-d spin-allowed and spin-forbidden transitions of Tb3+. In Dy3+-doped sample, the f-d spin-allowed transitions of Dy3+ and O2-?Dy3+ charge transfer band have not been clearly distinguished probably because of the overlapping with the strong host absorption band. The weak bands at 267 and 288 nm are attributed to be the f-d spin-forbidden transitions of Dy3+. The concentration dependence of the emission intensity upon the excitation at 172 nm indicates that the optimal doping concentrations of Tb3+ and Dy3+ are 11 mol% and 5 mol%, respectively. The optimal Tb3+ and Dy3+-activated samples respectively exhibit yellowish green and white emitting colors due to their characteristic emissions.

Zhang, Feng; Wang, Yuhua; Huang, Yan; Tao, Ye

2013-10-01

15

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

SciTech Connect

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

Zaremba, Roman [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster, Corrensstrasse 30, 48149 Muenster (Germany); Muts, Ihor [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster, Corrensstrasse 30, 48149 Muenster (Germany); Inorganic Chemistry Department, Ivan Franko National University of Lviv, Kyryla and Mephodiya Street 6, 79005 Lviv (Ukraine); Hoffmann, Rolf-Dieter [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster, Corrensstrasse 30, 48149 Muenster (Germany); Kalychak, Yaroslav M. [Inorganic Chemistry Department, Ivan Franko National University of Lviv, Kyryla and Mephodiya Street 6, 79005 Lviv (Ukraine)], E-mail: kalychak@franko.lviv.ua; Zaremba, Vasyl' I. [Inorganic Chemistry Department, Ivan Franko National University of Lviv, Kyryla and Mephodiya Street 6, 79005 Lviv (Ukraine); Poettgen, Rainer [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster, Corrensstrasse 30, 48149 Muenster (Germany)], E-mail: pottgen@uni-muenster.de

2007-09-15

16

Magnetic and magneto-topical properties of RMn{sub 6}Sn{sub 6} single crystals where R = Gd, Tb, Dy, Ho, Er, Tm, Lu  

SciTech Connect

Single crystals of the ternary compounds RMn{sub 6}Sn{sub 6}, where R = Gd, Tb, Dy, Ho, Er, Tm, and Lu, have been prepared by the flux growth technique. All of the compounds have the HfFe{sub 6}Ge{sub 6} type crystal structure (space group P6/mmm), and the variation of the lattice parameters with lanthanide element exhibits the lanthanide contraction as well as evidence of crystal field effects. Measurements on the magnetic properties of TbMn{sub 6}Sn{sub 6} indicate that it orders ferrimagnetically at 450K. It undergoes a change in the easy axis from close to the c axis at low temperatures to in plane at higher temperatures. This transition occurs at 310K in zero DC field and can be shifted to lower temperatures by a field applied parallel to the a direction and to higher temperatures by a field applied parallel to the c direction. HoMn{sub 6}Sn{sub 6} orders ferrimagnetically at 400K, and it also undergoes a change in the easy axis between 150 and 225K with the moments located in the basal plane at high temperatures. The magnetic properties of ErMn{sub 6}Sn{sub 6} are more complex than the first two compounds. A magnetic phase diagram has been mapped out which shows that in a zero DC field the erbium sublattice orders antiferromagnetically at 65K and the manganese sublattice orders antiferromagnetically at 350K. The structure of the room temperature magneto-optic spectra for RMn{sub 6}Sn{sub 6} with R = Gd-Tm are all similar. The maximum Kerr rotation found was 0.225 degrees in TbMn{sub 6}Sn{sub 6}, and the magnitude of the maximum Kerr rotations scaled across the series as a function of the fraction of saturation. This, combined with the temperature dependence, indicates that the Kerr rotation is primarily a function of the manganese moment and is independent of the lanthanide element present. The main features of the spectra shift to slightly higher energies as one moves from gadolinium to thulium. This may be related to the contraction in the lattice parameters. The materials show good corrosion resistance in normal atmospheric conditions.

Clatterbuck, D.M.

1999-02-12

17

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

PubMed

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

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

2003-12-01

18

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

19

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

PubMed

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

Chandrasekhar, Vadapalli; Bag, Prasenjit; Colacio, Enrique

2013-03-28

20

Crystal structures, physical properties and NMR experiments on the ternary rare-earth metal silicide boride compounds RE5Si2B8 (RE=Y, Sm, Gd, Tb, Dy, Ho)  

NASA Astrophysics Data System (ADS)

The ternary rare-earth metal silicide borides RE5Si2B8 (RE=Y, Sm, Gd, Tb, Dy Ho) were prepared by arc melting the elemental components and subsequent annealing up to T=1850K. The crystal structure was determined for each term of the series from single-crystal X-ray data: tetragonal symmetry, space group P4/mbm, Z=2; unit cell parameters a=7.2616(3), c=8.2260(3) and a=7.1830(2), c=7.9900(3) for Sm5Si2B8 and Ho5Si2B8, respectively. The structure is a new type and can be structurally described as an intergrowth of ThB4-like and U3Si2-like slabs of composition REB4 and RE3Si2, respectively, alternating along the c direction. The boron and silicon substructures are wholly independent and well ordered. The magnetic properties are as follows: Y5Si2B8 is a Pauli-type paramagnet above 1.8 K, Gd5Si2B8 undergoes a weak (canted) ferromagnetic-like order at 70 K followed by a colinear antiferromagnetic spin alignment at 44 K. Tb5Si2B8 and Dy5Si2B8 order antiferromagnetically at a Nel temperature of T=45 and 28 K, respectively. In the paramagnetic regime, the effective moments are in good accord with the theoretical RE3+ free ion moments. The temperature dependence of the electrical resistivities for the Y, Gd, Tb, and Dy containing samples corroborates with the metallic state of the nonmagnetic (Y) and the magnetically ordered compounds. 11B, 29Si and 89Y nuclear magnetic resonance (NMR) spectroscopy on nonmagnetic Y5Si2B8 shows different signals, which correspond to the expected number of distinct crystallographic sites in the structure. 11B NMR on Y5Si2B8 indicates that the local magnetic susceptibilities are substantially different from the ones observed in the related compound YB4.Graphical abstractIsothermal section of the phase diagram of Dy Si B system at 1270 K. Two-phase regions are dashed in grey.

Roger, Jrome; Babizhetskyy, Volodymyr; Cordier, Stphane; Bauer, Josef; Hiebl, Kurt; Le Polls, Laurent; Elisabeth Ashbrook, Sharon; Halet, Jean-Franois; Gurin, Roland

2005-06-01

21

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

22

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

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

23

Lanthanide salts of heteropoly molybdotungstosilicate LnHSiMo10W2O40xH2O (Ln = Pr, Nd, Sm, Gd, Tb, Dy, Yb) binding to bovine serum albumin: a fluorescence quenching study.  

PubMed

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

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

2011-12-16

24

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

25

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

SciTech Connect

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

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

2009-12-14

26

Magnetic characteristics of rare-earth indium R2In (R=Y, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm) intermetallic compounds  

Microsoft Academic Search

Measurements of the magnetic susceptibility of the R2In compounds from 4.2 to 270 K have been made. All compounds except Y2In and Sm2In exhibit Curie-Weiss behavior at high temperatures with effective magnetic moments agreeing reasonably well with the free-ion 3+ picture modified by RKKY exchange except for Gd2In, which gives an unusually high value for the effective moment. With the

Helen Gamari-Seale; T. Anagnostopoulos; J. K. Yakinthos

1979-01-01

27

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

NASA Astrophysics Data System (ADS)

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

Nishimoto, Kazue; Sato, Takeru; Tamura, Ryuji

2013-06-01

28

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

SciTech Connect

We present a detailed ARPES investigation of the RTe{sub 3} family, which sets this system as an ideal 'textbook' example for the formation of a nesting driven Charge Density Wave (CDW). This family indeed exhibits the full range of phenomena that can be associated to CDW instabilities, from the opening of large gaps on the best nested parts of Fermi Surface (FS) (up to 0.4eV), to the existence of residual metallic pockets. ARPES is the best suited technique to characterize these features, thanks to its unique ability to resolve the electronic structure in k-space. An additional advantage of RTe{sub 3} is that the band structure can be very accurately described by a simple 2D tight-binding (TB) model, which allows one to understand and easily reproduce many characteristics of the CDW. In this paper, we first establish the main features of the electronic structure, by comparing our ARPES measurements with Linear Muffin-Tin Orbital band calculations. We use this to define the validity and limits of the TB model. We then present a complete description of the CDW properties and, for the first time, of their strong evolution as a function of R. Using simple models, we are able to reproduce perfectly the evolution of gaps in k-space, the evolution of the CDW wave vector with R and the shape of the residual metallic pockets. Finally, we give an estimation of the CDW interaction parameters and find that the change in the electronic density of states n(Ef), due to lattice expansion when different R ions are inserted, has the correct order of magnitude to explain the evolution of the CDW properties.

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

2010-02-15

29

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

30

Energy Transfer in LaOBr:Tb,Gd.  

National Technical Information Service (NTIS)

Energy transfer in LaOBr : Tb0.075, Gdx (x<0.30) was investigated via excitation spectra, emission spectra, fluorescence decay function and X-ray diffraction. Effective energy transfer from Gd to Tb was found. With excitation of gamma = 275 nm, no Gd3+ bu...

Y. Wu H. Tang G. X. Zhu W. B. Zhao

1995-01-01

31

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) , b = 24.717(1) , and c = 11.651(2) , and V = 3394(1) (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

2013-02-11

32

Carbonato-bridged Ni(II)2Ln(III)2 (Ln(III) = Gd(III), Tb(III), Dy(III)) complexes generated by atmospheric CO2 fixation and their single-molecule-magnet behavior: [(?4-CO3)2{Ni(II)(3-MeOsaltn)(MeOH or H2O)Ln(III)(NO3)}2]solvent [3-MeOsaltn = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato].  

PubMed

Atmospheric CO2 fixation of [Ni(II)(3-MeOsaltn)(H2O)2]2.5H2O [3-MeOsaltn = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato], Ln(III)(NO3)36H2O, and triethylamine occurred in methanol/acetone, giving a first series of carbonato-bridged Ni(II)2Ln(III)2 complexes [(?4-CO3)2{Ni(II)(3-MeOsaltn)(MeOH)Ln(III)(NO3)}2] (1Gd, 1Tb, and 1Dy). When the reaction was carried out in acetonitrile/water, it gave a second series of complexes [(?4-CO3)2{Ni(II)(3-MeOsaltn)(H2O)Ln(III)(NO3)}2]2CH3CN2H2O (2Gd, 2Tb, and 2Dy). For both series, each Ni(II)2Ln(III)2 structure can be described as two di-?-phenoxo-bridged Ni(II)Ln(III) binuclear units bridged by two carbonato CO3(2-) units to form a carbonato-bridged (?4-CO3)2{Ni(II)2Ln(III)2} structure. The high-spin Ni(II) ion has octahedral coordination geometry, and the Ln(III) ion is coordinated by O9 donor atoms from Ni(II)(3-MeOsaltn), bidentate NO3(-), and one and two oxygen atoms of two CO3(2-) ions. The NO3(-) ion for the first series roughly lie on Ln-O(methoxy) bonds and are tilted toward the outside, while for the second series, the two oxygen atoms roughly lie on one of the Ln-O(phenoxy) bonds due to the intramolecular hydrogen bond. The temperature-dependent magnetic susceptibilities indicated a ferromagnetic interaction between the Ni(II) and Ln(III) ions (Ln(III) = Gd(III), Tb(III), Dy(III)) for all of the complexes, with a distinctly different magnetic behavior between the two series in the lowest-temperature region due to the Ln(III)-Ln(III) magnetic interaction and/or different magnetic anisotropies of the Tb(III) or Dy(III) ion. Alternating-current susceptibility measurements under the 0 and 1000 Oe direct-current (dc) bias fields showed no magnetic relaxation for the Ni(II)2Gd(III)2 complexes but exhibited an out-of-phase signal for Ni(II)2Tb(III)2 and Ni(II)2Dy(III)2, indicative of slow relaxation of magnetization. The energy barriers, ?/kB, for the spin flipping were estimated from the Arrhenius plot to be 12.2(7) and 6.1(3) K for 1Tb and 2Tb, respectively, and 18.1(6) and 14.5(4) K for 1Dy and 2Dy, respectively, under a dc bias field of 1000 Oe. Compound 1Dy showed relatively slow relaxation of magnetization reorientation even at zero dc applied field with ?/kB = 6.6(4) K. PMID:23706096

Sakamoto, Soichiro; Fujinami, Takeshi; Nishi, Koshiro; Matsumoto, Naohide; Mochida, Naotaka; Ishida, Takayuki; Sunatsuki, Yukinari; Re, Nazzareno

2013-05-24

33

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

PubMed

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

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

2008-06-30

34

Hyperfine field of156Gd in TbFe2, TbFe3, TbCo2 and TbCo3 compounds  

NASA Astrophysics Data System (ADS)

Time integral ?-? angular correlation measurements have been made on156Gd in Tb-3d metal compounds, TbFe2, TbFe3, TbCo2 and TbCo3, using two Ge(Li) detetctors. From the observation of a linear relation between magnetic hyperfine fields at Gd and Tb nuclei in corresponding compounds, it is inferred that crystalfield induced variations of the Tb moment are negligible. The experimental results are discussed in terms of the conduction electron polarization caused by the magnetic moment of 3d metals.

Shinohara, T.; Furusawa, A.; Hayashibe, S.; Kanazawa, M.; Sato, M.

1987-10-01

35

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

PubMed

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

Debasu, Mengistie L; Ananias, Duarte; Rocha, Joo; Malta, Oscar L; Carlos, Lus D

2013-10-01

36

Structure and magnetic properties of RE4CoCd and RE4RhCd (RE = Tb, Dy, Ho)  

Microsoft Academic Search

New rare earth metal rich cadmium compounds RE4CoCd and RE4RhCd (RE = Tb, Dy, Ho) were prepared by high-frequency melting of the elements in sealed tantalum tubes. The samples were studied by x-ray powder and single-crystal diffraction. All the compounds crystallize with Gd4RhIn-type structure, with space group F\\\\bar {4}3m . The structures are built up from rigid three-dimensional networks of

Ahmet Dogan; Sudhindra Rayaprol; Rainer Pttgen

2007-01-01

37

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

38

Hyperfine field at impurity 156Gd nuclei in TbT2 and TbT3 compounds (T = Fe and Co)  

NASA Astrophysics Data System (ADS)

The time integral ?-? perturbed angular correlation has been measured on 156Gd nuclei in TbFe2, TbFe3, TbCo2 and TbCo3 compounds. An obvious correlation is indicated between the hyperfine fields at Gd and Tb nuclei in corresponding compounds, and experimental results are discussed.

Shinohara, T.; Furusawa, A.; Hayashibe, S.; Kanazawa, M.; Sato, M.

1987-12-01

39

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

SciTech Connect

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

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

2009-05-12

40

New nuclide 139Tb and (EC +?+) decay of 138,139Gd  

NASA Astrophysics Data System (ADS)

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

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

41

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

SciTech Connect

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

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

1995-11-01

42

Magnetic properties of RE 2Ni 3Si 5 (RE ? Nd, Tb and Dy)  

Microsoft Academic Search

Magnetic properties of Dy2Ni3Si5 and the two new materials Nd2Ni3Si5 and Tb2Ni3Si5 are presented. Both Nd2Ni3Si5 and Dy2Ni3Si5 order antiferromagnetically with TN ? 9.5 K. Tb2Ni3Si5 shows two distinct magnetic transitions at TN1 ? 19.5 K and at TN2 ? 12 K. In the paramagnetic state, all these materials exhibit Curie-Weiss behaviour.

Chandan Mazumdar; R. Nagarajan; L. C. Gupta; B. D. Padalia; R. Vijayaraghavan

1995-01-01

43

Magnetic properties of RE2Ni3Si5 (RE = Nd, Tb and Dy)  

Microsoft Academic Search

Magnetic properties of Dy2Ni3Si5 and the two new materials Nd2Ni3Si5 and Tb2Ni3Si5 are presented. Both Nd2Ni3Si5 and Dy2Ni3Si5 order antiferromagnetically with TN ~ 9.5 K. Tb2Ni3Si5 shows two distinct magnetic transitions at TN1 ~ 19.5 K and at TN2 ~ 12 K. In the paramagnetic state, all these materials exhibit Curie-Weiss behaviour.

R. Nagarajan; L. C. Gupta; R. Vijayaraghavan; C. Mazumdar; B. D. Padalia

1995-01-01

44

Extreme ultraviolet emission spectra of Gd and Tb ions  

SciTech Connect

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

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

2010-11-15

45

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

NASA Astrophysics Data System (ADS)

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

Liu, Xiaoyang; Fleet, Michael E.

2002-11-01

46

Optical Characterization of Tb3+-Doped Gd2O3 Based Scintillating Glasses  

NASA Astrophysics Data System (ADS)

We prepared Tb3+-doped Gd2O3-based oxide glasses by high-temperature melting method and presented their density and optical characterization including transmission, emission and excitation spectra. Dependence of density and luminescence properties on the concentration of Tb3+ and Gd2O3 was also analyzed. The results show that rising Tb3+ ions concentrations would lead to the reduction of distance between Tb3+ ions, the increase of probabilities of energy resonate-transfer and a stronger luminous intensity. In addition, a high Gd2O3 concentration was beneficial to improve the glass samples density, but exerting a negative effect on Tb3+ ions and decreasing the luminous intensity of Tb3+ ions.

Lai, Fei; Zhang, Yue-Pin; Xia, Hai-Ping; Wang, Jin-Hao; He, Wei

2013-09-01

47

Synthesis of KNaSO4:Tb3+ and MgSO4:Dy3+ phosphors for lyoluminescence dosimetry  

NASA Astrophysics Data System (ADS)

KNaSO4:Tb3+ phosphors were synthesized by melt technique with different concentration of Tb3+ ions and MgSO4:Dy3+ phosphor is prepared by solid state diffusion method. Lyoluminescence and photoluminescence characterization of KNaSO4:Tb and MgSO4:Dy3+ phosphors are reported in this paper. Only one sharp peak is observed in the lyoluminescence (LL) glow curve and KNaSO4:Tb(0.05 mol%) phosphor shows maximum efficiency. The LL intensity increases linearly with gamma ray dose. LL emission occurs in the blue and yellow region of the spectrum. Photoluminescence (PL) characterization of KNaSO4:Tb(0.05 mol%) phosphor shows PL emission at 486 and 546 nm. These PL emissions from KNaSO4:Tb3+ are due to 5D4 ? 7F6 and 5D4 ? 7F5 transitions of Tb3+ ion respectively. Lyoluminescence of MgSO4:Dy3+ phosphor shows the high sensitivity to ?-ray exposure and LL emission observed at 486 and 572 nm in the blue and yellow emission of the spectrum is due to Dy3+ ion. Experimental results obtained in the present investigation show that KNaSO4:Tb3+ and MgSO4:Dy3+ phosphors are suitable as a lyoluminescence dosimetry phosphor for ionizing radiations.

Upadhyay, A.; Dhoble, S. J.; Rai, R.; Kher, R. S.

2008-06-01

48

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

Microsoft Academic Search

At cryogenic temperatures, single crystals of TbDy alloys exhibit giant magnetostrictions of nearly 9000 ppm, making these materials promising for engineering service in cryogenic actuators, valves, and positioners. The preparation of single crystals is difficult and costly. Preliminary results on the magnetostriction of textured polycrystalline materials are presented here. For instance, polycrystalline Tb0.60Dy0.40, plane-rolled (one direction of applied stress) to

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

1999-01-01

49

Investigation of Gd and Tb plasmas for beyond extreme ultraviolet lithography based on multilayer mirror performance  

NASA Astrophysics Data System (ADS)

Recent work on multilayer mirror development for beyond extreme ultraviolet lithography indicates that their optimum reflectivity occurs at either 6.63 nm or 6.66 nm which may be too short a wavelength for Gd-based plasma sources. Calculations performed for Tb12+ to Tb28+ ions show that if the mirror reflectivity is fixed at one of these values, Tb may be a better source, though Gd is capable of providing greater intensity if the full reflection curve of the mirrors is exploited. Theoretical simulation shows that the Tb emission peaks close to 6.51 nm at an optimum electron temperature close to 120 eV.

Li, Bowen; Otsuka, Takamitsu; Higashiguchi, Takeshi; Yugami, Noboru; Jiang, Weihua; Endo, Akira; Dunne, Padraig; O'Sullivan, Gerry

2012-07-01

50

Preparation and the luminescent properties of Tb3 + -doped Gd2O3 fluorescent nanofibers via electrospinning  

Microsoft Academic Search

Tb3 + -doped Gd2O3 (Gd2O3:Tb3 + ) nanofibers were prepared via a simple electrospinning technique using poly(ethylene oxide) (PEO) and rare-earth acetate tetrahydrates (Ln(CH3COO)34H2O (Ln = Gd, Tb)) as precursors. The obtained nanofibers have an average diameter of about 80 nm and are composed of pure cubic Gd2O3 phase. A possible formation mechanism for the nanofibers is proposed on the

Pingfan Du; Lixin Song; Jie Xiong; Zhenqiang Xi; Dalai Jin; Longcheng Wang

2011-01-01

51

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

NASA Astrophysics Data System (ADS)

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

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

2007-10-01

52

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

53

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

54

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

SciTech Connect

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

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

2011-01-15

55

Determination of Dy(III) in the presence of Tb(III) using time-resolved luminescence  

NASA Astrophysics Data System (ADS)

We have measured the relative luminescence quantum yields and luminescence lifetimes of Tb(III) and Dy(III) ions in complexes with pyrazole-5-carboxylic acids. Based on study of the time-resolved luminescence spectra of Tb(III) and Dy(III) complexes with 3-(6-benzodioxanyl)pyrazole-5-carboxylic acid, we have demonstrated the possibility in principle of determining Dy(III) in the presence of Tb(III) by separating the short-lived component of the luminescence of dysprosium, despite the practically complete overlap of the analytical bands of dysprosium by the terbium bands. This method was used to determine Dy(III) in luminescent materials: scandium borates doped with terbium and dysprosium.

Tsvirko, M. P.; Kiriyak, A. V.; Meshkova, S. B.

2007-05-01

56

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]2dmfH2O (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 Jnior, Anderson A. B.; Ribeiro, Sidney J. L.; Scaldini, Felipe M.; Machado, Flvia C.

2013-10-01

57

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

PubMed

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

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

2013-03-20

58

Structural Studies of Layered Cuprates LnLn'CaBa_2Cu_2Ti_3O_14 (LnLn' = NdY, Tb2, TbY, Dy2 and DyY) by Neutron Powder Diffraction  

NASA Astrophysics Data System (ADS)

In this presentation we report the neutron powder diffraction studies on several compounds in a new family of layered cuprates, LnLn'CaBa_2Cu_2Ti_3O_14 (LnLn' = NdY, Tb2, TbY, Dy2 and DyY). All compounds are found to crystallize in space group P 4/mmm. Strong site preferences of B-action (Cu and Ti) are observed in the NdY, Tb2 and TbY systems where Cu atoms strongly prefer 2g (0 0 0.084) sites. Due to the similar neutron scattering length of Nd, Tb, and Y, it is difficult to determine A-cation distributions in the NdY, Tb2 and TbY systems. In the DyY case, however, Dy atoms are found to strongly prefer site the 1 c (0.5 0.5 0) and do not mix with Y atoms on the (0.5 0.5 0.188) sites. The mechanism for these site preferences will be discussed. The oxygen content is found to be slightly different from the theoretical value for all compounds.

Hu, Z.; Jorgensen, J. D.; Short, S.; Otzschi, K. D.; Poeppelmeier, K. R.; Vander Griend, D.; Kane, M. H.

1998-03-01

59

Lifetime Measurements of Superdeformed Bands in 148-149Gd and 152Dy:Evidence for Structure-Dependent Elongations  

Microsoft Academic Search

Precise level lifetimes have been measured for various superdeformed bands in 148,149Gd and 152Dy with the Doppler-shift attenuation method. From the derived quadrupole moments, Q0, we find large differences in deformation between the yrast bands and some excited bands in the gadolinium isotopes. Moreover, two of the excited Gd bands and the 152Dy yrast band, which have identical moments of

H. Savajols; A. Korichi; D. Ward; D. Appelbe; G. C. Ball; C W Beausang; F. A. Beck; T. Byrski; D. Curien; P. Dagnall; G. de France; D. Disdier; G. Duchne; S. Erturk; C. Finck; S. Flibotte; B. Gall; A. Galindo-Uribarri; B. Haas; G. Hackman; V. P. Janzen; B. Kharraja; J. C. Lisle; J. C. Merdinger; S. M. Mullins; S. Pilotte; D. Prvost; D. C. Radford; V. Rauch; C. Rigollet; D. Smalley; M. B. Smith; O. Stezowski; J. Styczen; Ch. Theisen; P. J. Twin; J. P. Vivien; J. C. Waddington; K. Zuber; I. Ragnarsson

1996-01-01

60

Characterization of {beta}'' precipitate phase in a Mg-Dy-Gd-Nd alloy  

SciTech Connect

The morphology and crystal structure of {beta}'' precipitate phases in a Mg-Dy-Gd-Nd system have been studied using transmission electron microscopy and X-ray diffraction. Three orientation relationships have been observed between {beta}'' precipitate phases and the {alpha} matrix phase with the habit plane parallel to {l_brace}112-bar 0{r_brace}{sub {alpha}}. The orientation relationship between the {beta}'' precipitates and the matrix is [0001]{sub {beta}}{sub ''}//[0001]{sub {alpha}}, [11-bar 00]{sub {beta}}{sub ''}//[11-bar 00]{sub {alpha}}. The structure of the {beta}''phase, with the interspaces between Dy/Gd/Nd atoms filled with magnesium atoms, is completely consistent with that of the matrix.

Li, D.H. [School of Material Science and Engineering, Shanghai Jiaotong University, Shanghai, 20030 (China)], E-mail: lidehuilee@sjtu.edu.cn; Dong, J.; Zeng, X.Q.; Lu, C.; Ding, W.J. [School of Material Science and Engineering, Shanghai Jiaotong University, Shanghai, 20030 (China)

2007-10-15

61

Magnetic properties of RFe6Ga6 compounds (R=Gd, Dy, Ho, Er, Tm)  

Microsoft Academic Search

We have studied the magnetic properties of several ternary rare-earth compounds of the composition RFe6Ga6 (R=Gd, Dy, Ho, Er, Tm) by means of magnetization measurements in high fields up to 35T. All these compounds cystallize in the tetragonal ThMn12 type of structure. This structure has three non-rare-earth sites. Previous neutron-diffraction studies have shown that the Fe and Ga atoms preferentially

Y. Janssen; R. T. Gramsma; J. C. P. Klaasse; E. Brck; K. H. J. Buschow; F. R. de Boer

2001-01-01

62

Magnetic properties of RFe 6Ga 6 compounds (R=Gd, Dy, Ho, Er, Tm)  

Microsoft Academic Search

We have studied the magnetic properties of several ternary rare-earth compounds of the composition RFe6Ga6 (R=Gd, Dy, Ho, Er, Tm) by means of magnetization measurements in high fields up to 35T. All these compounds cystallize in the tetragonal ThMn12 type of structure. This structure has three non-rare-earth sites. Previous neutron-diffraction studies have shown that the Fe and Ga atoms preferentially

Y. Janssen; R. T. Gramsma; J. C. P. Klaasse; E. Brck; K. H. J. Buschow; F. R. de Boer

2001-01-01

63

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

PubMed

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

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

2013-06-21

64

Morphotropic phase boundaries in ferromagnets: Tb(1-x)Dy(x)Fe2 alloys.  

PubMed

The structure and properties of the ferromagnet Tb(1-x)Dy(x)Fe(2) are explored through the morphotropic phase boundary (MPB) separating ferroic phases of differing symmetry. Our synchrotron data support a first order structural transition, with a broadening MPB width at higher temperatures. The optimal point for magnetomechanical applications is not centered on the MPB but lies on the rhombohedral side, where the high striction of the rhombohedral majority phase combines with the softened anisotropy of the MPB. We compare our findings with single ion crystal field theory and with ferroelectric MPBs, where the controlling energies are different. PMID:23863024

Bergstrom, Richard; Wuttig, Manfred; Cullen, James; Zavalij, Peter; Briber, Robert; Dennis, Cindi; Garlea, V Ovidiu; Laver, Mark

2013-07-03

65

Cross sections of proton-induced reactions on natGd with special emphasis on the production possibilities of 152Tb and 155Tb  

NASA Astrophysics Data System (ADS)

Cross sections and physical yields are presented for various Tb radionuclides formed in the bombardment of natGd with protons, from their respective thresholds up to 66 MeV. New measurements 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 previous literature experimental data, where available.Based on the agreement between the experimental results and the theoretical predictions, integral thick-target yields are also derived for the 152Gd(p,n) 152Tb, 155Gd(p,n) 155Tb and 155Gd(p,4n) 152Tb reactions forming the medically important 152gTb (SPECT) and 155Tb (PET) radionuclides.

Vermeulen, C.; Steyn, G. F.; Szelecsnyi, F.; Kovcs, Z.; Suzuki, K.; Nagatsu, K.; Fukumura, T.; Hohn, A.; van der Walt, T. N.

2012-03-01

66

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

NASA Astrophysics Data System (ADS)

Some novel kinds of hybrid phosphors were assembled with lanthanum (Tb, Eu, Dy) complexes (with four kinds of terbium complexes is 2,4-dihydroxybenzonic acid (DHBA), 1,10-phenanthroline (phen), acetylacetone (AA) and nicotinic acid (Nic), respectively) doped ZnO/PEG particles by co-precipitation approach derived from Zn(CH3COO)2 (Zn(AC)2), NaOH, PEG as precursors at room temperature. The characteristic luminescence spectra for f f transitions of Tb3+, Eu3+, Dy3+ were observed. It is worthy to point out that ZnO is the excellent host for lanthanum ions by the assembly of PEG matrices.

Yan, Bing; Chen, Xi; Wu, Jianhua

2007-08-01

67

Controlled shape growth of Eu- or Tb-doped luminescent Gd2O3 colloidal nanocrystals.  

PubMed

Controlled-shape synthesis of rare earth doped gadolinium oxide (Gd(2)O(3):Eu(3+) or Tb(3+)) colloidal nanocrystals by non-hydrolytic high temperature (approximately 290 degrees C) solution growth methods is reported. Various shapes of Gd(2)O(3) nanocrystals were synthesized, including spheres, plates, and curved rods. The nanocrystal shape was shown to be dependent on the synthesis parameters, such as type of metal precursor and surfactant, and their concentration ratio. The photoluminescence intensity from rare earth doped Gd(2)O(3) was shown to increase from nanoplates to nanospheres, which is discussed in terms of doping efficiency, crystal structure, and ratio of surface to volume. PMID:19027121

Seo, Sooyeon; Yang, Heesun; Holloway, Paul H

2008-11-12

68

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

69

Synthesis of green-emitting (Gd, La, Tb)2O(WO4)2 phosphors  

NASA Astrophysics Data System (ADS)

Green-emitting (Gd1-x-yLaxTby)2O(WO4)2 (0 ? x ? 0.05, 0.05 ? y ? 0.15) phosphors were synthesized in a single phase form by the conventional solid-state reaction method, and their photoluminescent properties were characterized. The (Gd1-x-yLaxTby)2O(WO4)2 phosphors showed strong and broad excitation bands from 230 to 350 nm, corresponding to the energy transition from the 4f8 to 4f75d configuration of Tb3+ and the charge-transfer (CT) transition of O2--W6+. The oxytungstate phosphors exhibited typical emission peaks assigned to the transition from 5D4 to 7FJ (J = 6, 5, 4, and 3) of Tb3+, and the luminescence emission intensity was effectively enhanced by the La3+ doping into the host Gd2O(WO4)2 lattice. The highest green emission intensity was obtained for (Gd0.87La0.03Tb0.10)2O(WO4)2, where the relative emission intensity was 63% that of a commercial green-emitting (La0.52Ce0.31Tb0.17)PO4 phosphor.

Kim, Sun Woog; Masui, Toshiyuki; Imanaka, Nobuhito

2013-10-01

70

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

71

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

SciTech Connect

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

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

2006-07-10

72

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

2013-08-01

73

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

PubMed Central

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

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

2009-01-01

74

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

75

Syntheses, crystal structures and vibrational spectra of KLn(SO).HO (Ln=La, Nd, Sm, Eu, Gd, Dy)  

Microsoft Academic Search

The potassium lanthanide double sulphates KLn(SO).HO (Ln=La, Nd, Sm, Eu, Gd, Dy) were obtained by evaporation of aqueous reaction mixtures of rare earth (III) sulphates and potassium thiocyanate at 298 K. X-ray single-crystal investigations show that KLn(SO).HO (Ln=Nd, Sm, Eu, Gd, Dy) crystallise monoclinically (Ln=Sm: P2\\/c, Z=4, a=10.047(1), b=8.4555(1), c=10.349(1) A, wR2=0.060, R1=0.024, 945 reflections, 125 parameters) while KLa(SO).HO adopts

Karolina Kazmierczak; Henning A. Hoeppe

2010-01-01

76

Intelligent epoxy matrix composite materials consisting of Tb0.3Dy0.7Fe1.9 magnetostrictive particulates  

Microsoft Academic Search

Purpose: This paper presents the acceptable technology to fabricate epoxy-bonded Tb0.3Dy0.7Fe1.9 composites in an effort to produce Tb0.3Dy0.7Fe1.9 bulks with good magnetostrictive properties through the optimization of some fabrication parameters. Design\\/methodology\\/approach: Intelligent polymer matrix composite materials consisting of magnetostrictive particulates was obtained by homogenously mixing low viscosity epoxy resin and Tb0.3Dy0.7Fe1.9 powder with grains from 38 to 106 ?m. The

L. A. Dobrzaski; A. Wydrzyska; O. Iesenchuk

77

Elastic properties of the rare-earth dititanates R2Ti2O7 (R=Tb, Dy, and Ho)  

Microsoft Academic Search

We have performed ultrasonic measurements on the alpha-pyrochlore spin compounds R2Ti2O7, R= Tb, Dy, and Ho. A distinct dip appears around 80 K, especially in transverse modes (C11-C12)\\/2 and C44 as a function of temperature in Dy2Ti2O7 and Ho2Ti2O7 compounds. This anomaly may correspond to a structural change detected by the temperature dependence of the permittivity and of the loss-angle

Y. Nakanishi; T. Kumagai; M. Yoshizawa; K. Matsuhira; S. Takagi; Z. Hiroi

2011-01-01

78

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

SciTech Connect

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

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

2012-08-15

79

Effects of the host lattice and doping concentration on the colour of Tb3+ cation emission in Y2O2S:Tb3+ and Gd2O2S:Tb3+ nanometer sized phosphor particles  

NASA Astrophysics Data System (ADS)

Y2O2S and Gd2O2S phosphor lattices activated with a range of Tb3+ concentrations have been successfully prepared as nanoparticles and their emission properties have been characterized using SEM, XRPD, photoluminescence spectroscopy and cathodoluminescence. 5D3-5D4 cross relaxation processes between Tb3+ cations were observed in both Y2O2S and Gd2O2S as a function of Tb3+ concentration. In the Y2O2S host lattice, the predominant emission colour shifts from blue to green with increased Tb3+ concentration. In contrast, green emission is always predominant in Gd2O2S at Tb3+ concentrations from 0.1 mol% to 5 mol%. This finding is explained in accordance with previous reports on the bulk materials that found the Gd2O2S lattice has a lower charge transfer state than the Y2O2S host lattice.

Yan, Xiao; Fern, George R.; Withnall, Robert; Silver, Jack

2013-08-01

80

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

NASA Astrophysics Data System (ADS)

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

Das, Raja; Jaiswal, Adhish; Poddar, Pankaj

2013-01-01

81

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

PubMed

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

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

2007-07-04

82

Room temperature synthesis of hydrophilic Ln3+-doped KGdF4 (Ln = Ce, Eu, Tb, Dy) nanoparticles with controllable size: energy transfer, size-dependent and color-tunable luminescence properties  

NASA Astrophysics Data System (ADS)

In this paper, we demonstrate a simple, template-free, reproducible and one-step synthesis of hydrophilic KGdF4: Ln3+ (Ln = Ce, Eu, Tb and Dy) nanoparticles (NPs) via a solution-based route at room temperature. X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) and cathodoluminescence (CL) spectra are used to characterize the samples. The results indicate that the use of water-diethyleneglycol (DEG) solvent mixture as the reaction medium not only allows facile particle size control but also endows the as-prepared samples with good water-solubility. In particular, the mean size of NPs is monotonously reduced with the increase of DEG content, from 215 to 40 nm. The luminescence intensity and absolute quantum yields for KGdF4: Ce3+, Tb3+ NPs increase remarkably with particle sizes ranging from 40 to 215 nm. Additionally, we systematically investigate the magnetic and luminescence properties of KGdF4: Ln3+ (Ln = Ce, Eu, Tb and Dy) NPs. They display paramagnetic and superparamagnetic properties with mass magnetic susceptibility values of 1.03 10-4 emu g-1.Oe and 3.09 10-3 emu g-1.Oe at 300 K and 2 K, respectively, and multicolor emissions due to the energy transfer (ET) process Ce3+ --> Gd3+ --> (Gd3+)n --> Ln3+, in which Gd3+ ions play an intermediate role in this process. Representatively, it is shown that the energy transfer from Ce3+ to Tb3+ occurs mainly via the dipole-quadrupole interaction by comparison of the theoretical calculation and experimental results. This kind of magnetic/luminescent dual-function materials may have promising applications in multiple biolabels and MR imaging.In this paper, we demonstrate a simple, template-free, reproducible and one-step synthesis of hydrophilic KGdF4: Ln3+ (Ln = Ce, Eu, Tb and Dy) nanoparticles (NPs) via a solution-based route at room temperature. X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) and cathodoluminescence (CL) spectra are used to characterize the samples. The results indicate that the use of water-diethyleneglycol (DEG) solvent mixture as the reaction medium not only allows facile particle size control but also endows the as-prepared samples with good water-solubility. In particular, the mean size of NPs is monotonously reduced with the increase of DEG content, from 215 to 40 nm. The luminescence intensity and absolute quantum yields for KGdF4: Ce3+, Tb3+ NPs increase remarkably with particle sizes ranging from 40 to 215 nm. Additionally, we systematically investigate the magnetic and luminescence properties of KGdF4: Ln3+ (Ln = Ce, Eu, Tb and Dy) NPs. They display paramagnetic and superparamagnetic properties with mass magnetic susceptibility values of 1.03 10-4 emu g-1.Oe and 3.09 10-3 emu g-1.Oe at 300 K and 2 K, respectively, and multicolor emissions due to the energy transfer (ET) process Ce3+ --> Gd3+ --> (Gd3+)n --> Ln3+, in which Gd3+ ions play an intermediate role in this process. Representatively, it is shown that the energy transfer from Ce3+ to Tb3+ occurs mainly via the dipole-quadrupole interaction by comparison of the theoretical calculation and experimental results. This kind of magnetic/luminescent dual-function materials may have promising applications in multiple biolabels and MR imaging. Electronic supplementary information (ESI) available: XRD patterns of KGdF4: Ce3+, Tb3+ and KGdF4 NPs. Schematic energy level diagram showing the luminescence mechanism in KGdF4: Ce3+, Ln3+ nanoparticles. Excitation and emission spectra of KGdF4: Ce3+/Ln3+ (Ln = Eu, Tb, Dy, Eu/Tb and Eu/Tb/Dy) nanoparticles, and the KGdF4: 5% Ce3+, 4% Tb3+@KGdF4. CL spectra of the KGdF4: 5% Ce3+, 4% Tb3+ nanoparticles with different size. The SEM image of KGdF4: Ce3+/Tb3+@KGdF4 nanoparticles. TEM images, and emission spectra of KGdF4: 5% Ce3+, 5% Tb3+ NPs prepared by solvothermal, co-precipitation,

Yang, Dongmei; Li, Guogang; Kang, Xiaojiao; Cheng, Ziyong; Ma, Ping'an; Peng, Chong; Lian, Hongzhou; Li, Chunxia; Lin, Jun

2012-05-01

83

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

Microsoft Academic Search

We have characterized a textured cylindrical sample of Tb0.5Dy0.5Fe2 (54 mm6 mm diam) by topography and metallography. The topography shows long ( 20 mm) slender grains with a [110] axis along the sample axis. The grain boundaries are less than 1. Domain walls can be seen by both BergBarrett technique and optical observations. This composition has a large anisotropy, Ki=5106

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

1985-01-01

84

Magnetization reversal in exchange-coupled GdFe\\/TbFe studied by x-ray magnetic circular dichroism  

Microsoft Academic Search

This work is dedicated to the study of magnetization reversal processes in a ferromagnetically exchange coupled ferrimagnetic\\/ferrimagnetic bilayer system made of a soft magnetic GdFe layer and a hard TbFe layer. Regular magnetization measurements and x-ray magnetic circular dichroism (XMCD) measurements performed at the ESRF on a GdFe (100 nm)\\/TbFe (3 nm) bilayer at different temperatures are presented and compared.

S. Mangin; C. Bellouard; S. Andrieu; F. Montaigne; P. Ohresser; N. B. Brookes; B. Barbara

2004-01-01

85

Crystal structure of Tb5Ni2In4, and magnetic properties of Dy5Ni2In4  

SciTech Connect

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

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

2012-02-27

86

Structural and magnetic phase transitions in TbRuAsO and DyRuAsO  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

87

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

SciTech Connect

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

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

2011-04-15

88

Magnetic anisotropy in (Tb0.3Dy0.7)45Fe55 amorphous films  

NASA Astrophysics Data System (ADS)

Giant magnetostrictive (Tb0.3Dy0.7)45Fe55 thin films were prepared by direct current (DC) magnetron sputtering. The onset temperature of crystallization of the films is found to be 407C through differential scanning calorimetery (DSC) studies. X-ray diffraction analysis confirms that the films exhibit an amorphous phase after annealing at 400C. The effect of annealing on the in-plane anisotropy was investigated. The in-plane anisotropy is enhanced upon increasing the annealing temperature from 200C to 400C. The ratio Mr/M10 is varied from 0.037 for the as-deposited sample to 0.543 after annealing at 400C, where Mr and M10 refer to remanence and magnetization measured at the field of 10kOe, respectively. In addition, pre-stress was also applied during deposition to induce an in-plane unidirectional anisotropy in the films. This may result in an anisotropy of the in-plane magnetization and lead to a large improvement of magnetostriction.

Xu, H.; Jiang, C.; Jiang, X.; Gong, S.

2001-06-01

89

Stoichiometric study of Tb(x)Dy(1-x)Fe2 particulate composites for passive damping  

NASA Astrophysics Data System (ADS)

Magnetostrictive particulate composites promises to be a revolutionary new damping solution with possible loss factors similar to current viscoelastic systems but coupled with a significantly higher modulus ~ 10GPa. Magnetostrictive particulate composites fabricated from Terfenol-D (TbxDy1-xFe1.92) particles and epoxy resin, were mechanically tested under cyclic compressive loads in an MTS load frame to determine hysteric losses, from which an approximate tan? was derived to quantify damping performance. DMA results on the same composites corroborated the MTS results. Various off-stoichiometric compositions of Terfenol-D were studied with varying Tb composition of x = 0.35, 0.4, 0.45, 0.5, 0.75 and 1.0. Results indicated better damping with higher Tb compositions peaking at Tb=0.5.

Ho, Ken K.; Kerrigan, Catherine; Luna, Omar; Carman, Gregory P.

2005-05-01

90

Preparation and the luminescent properties of Tb3 + -doped Gd2O3 fluorescent nanofibers via electrospinning  

NASA Astrophysics Data System (ADS)

Tb3 + -doped Gd2O3 (Gd2O3:Tb3 + ) nanofibers were prepared via a simple electrospinning technique using poly(ethylene oxide) (PEO) and rare-earth acetate tetrahydrates (Ln(CH3COO)34H2O (Ln = Gd, Tb)) as precursors. The obtained nanofibers have an average diameter of about 80 nm and are composed of pure cubic Gd2O3 phase. A possible formation mechanism for the nanofibers is proposed on the basis of the experimental results, which reveals that PEO acts as the structure directing template during the whole electrospinning and subsequent calcination process. The luminescent properties of the nanofibers were investigated in detail. The nanofibers exhibit a favorable fluorescent property symbolized by the characteristic green emission (545 nm) resulting from the ^{5} {D_{4}} \\to {}^{7} {F_{5}} transition of Tb3 + . Concentration quenching occurs when the Tb3 + concentration is 3 at.%, indicating that the Gd2O3:Tb3 + nanofibers have an optimum luminescent intensity under such a doping concentration.

Du, Pingfan; Song, Lixin; Xiong, Jie; Xi, Zhenqiang; Jin, Dalai; Wang, Longcheng

2011-01-01

91

Preparation and the luminescent properties of Tb3+-doped Gd2O3 fluorescent nanofibers via electrospinning.  

PubMed

Tb(3+)-doped Gd(2)O(3) (Gd(2)O(3):Tb(3+)) nanofibers were prepared via a simple electrospinning technique using poly(ethylene oxide) (PEO) and rare-earth acetate tetrahydrates (Ln(CH(3)COO)(3)4H(2)O (Ln = Gd, Tb)) as precursors. The obtained nanofibers have an average diameter of about 80 nm and are composed of pure cubic Gd(2)O(3) phase. A possible formation mechanism for the nanofibers is proposed on the basis of the experimental results, which reveals that PEO acts as the structure directing template during the whole electrospinning and subsequent calcination process. The luminescent properties of the nanofibers were investigated in detail. The nanofibers exhibit a favorable fluorescent property symbolized by the characteristic green emission (545 nm) resulting from the 5D4-->7F5 transition of Tb(3+). Concentration quenching occurs when the Tb(3+) concentration is 3 at.%, indicating that the Gd(2)O(3):Tb(3+) nanofibers have an optimum luminescent intensity under such a doping concentration. PMID:21149966

Du, Pingfan; Song, Lixin; Xiong, Jie; Xi, Zhenqiang; Jin, Dalai; Wang, Longcheng

2010-12-09

92

Synthesis of high-performance magnetostrictive Tb0.3Dy0.7Fe2 by unidirectional solidification in microgravity.  

PubMed

Giant magnetostrictive materials, Tb(0.297)Dy(0.679)Fe(2), were synthesized by unidirectional solidification of a mixture of Tb(0.99)Fe(2) and Dy(0.97)Fe(2) alloys in microgravity with magnetic field of 0-0.12 T. Tb(0.297)Dy(0.679)Fe(2) is a mixed crystal of TbFe(2) and DyFe(2). Tb(0.297)Dy(0.679)Fe(2) synthesized in microgravity with no magnetic field had sheet dendrites structure with 300 (cooling direction) x 200 x 30 microm (thickness) and Fe-rich layer between the sheet dendrites, and they exhibited a tendency for crystalline orientation of <110> and <111> with the cooling direction. The magnetostriction with the cooling direction was 9000 ppm at an external magnetic field of 120 mT. In contrast, Tb(0.297)Dy(0.679)Fe(2) synthesized by unidirectional solidification in normal gravity with no magnetic field had a dendrite structure with a 30-mum diameter x 250-microm length growing in the cooling direction and no preferred orientation. The magnetostriction along the cooling direction was 2000 ppm at an external magnetic field of 120 mT. Analysis of the solidification in microgravity with magnetic field revealed that the dendrites oriented along the cooling direction and that the tendency for crystalline orientation of <110> and <111> with the cooling direction increased with magnetic field. Examination of the solidification in normal gravity with magnetic field indicated that Tb(0.297)Dy(0.679)Fe(2) consisted of sheet dendrites without orientation and revealed no preferred orientation. The magnetostriction along the cooling direction increased with increases in the magnetic field. The effects of microgravity and magnetic field on the structure and crystalline orientation were considered. PMID:19426337

Okutani, Takeshi; Nagai, Hideaki; Mamiya, Mikito

2009-04-01

93

Lifetime measurements of superdeformed bands in {sup 148149}Gd and ¹⁵²Dy: Evidence for structure-dependent elongations  

Microsoft Academic Search

Precise level lifetimes have been measured for various superdeformed bands in {sup 148,149}Gd and ¹⁵²Dy with the Doppler-shift attenuation method. From the derived quadrupole moments, {ital Q}, we find large differences in deformation between the yrast bands and some excited bands in the gadolinium isotopes. Moreover, two of the excited Gd bands and the ¹⁵²Dy yrast band, which have identical

H. Savajols; A. Korichi; D. Ward; D. Appelbe; G. Ball; C. Beausang; F. Beck; T. Byrski; D. Curien; P. Dagnall; G. de France; D. Disdier; G. Duchene; S. Erturk; C. Finck; S. Flibotte; B. Gall; A. Galindo-Uribarri; B. Haas; G. Hackman; V. Janzen; B. Kharraja; J. Lisle; J. Merdinger; S. Mullins; S. Pilotte; D. Prevost; D. Radford; V. Rauch; C. Rigollet; D. Smalley; M. Smith; O. Stezowski; J. Styczen; C. Theisen; P. Twin; J. Vivien; J. Waddington; K. Zuber; I. Ragnarsson

1996-01-01

94

Study of spin and orbital magnetization in Dy- and Gd-doped Co ferrite using magnetic Compton scattering  

NASA Astrophysics Data System (ADS)

Temperature dependent experimental magnetic Compton profiles (MCPs) of inverse spinel CoFe2-xRExO4 (x = 0.05 RE = Dy, Gd) have been decomposed into constituent profiles to determine site-specific spin moments. A comparison of MCPs of doped and undoped CoFe2O4 shows a decrease in spin moment on 5% doping of Dy and Gd. Reduction in spin moment is explained on the basis of migration of Co2+ ions from octahedral to tetrahedral sites, which is also supported by photoelectron spectroscopy measurements. The orbital moments deduced from combination of spin momentum density and magnetization data are found to be almost similar in doped ferrites.

Mund, H. S.; Sahariya, Jagrati; Choudhary, R. J.; Phase, D. M.; Dashora, Alpa; Itou, M.; Sakurai, Y.; Ahuja, B. L.

2013-06-01

95

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

NASA Astrophysics Data System (ADS)

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

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

2005-09-01

96

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

NASA Astrophysics Data System (ADS)

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

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

2009-10-01

97

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

Microsoft Academic Search

The magnetic susceptibility of Al2REM (REM = Gd, Dy, and Ho) intermetallic compounds is experimentally investigated by the Faraday method in a wide temperature interval (290-2000 K) in different magnetic fields (0.3-1.3 T). In the crystalline state, the temperature dependences of the susceptibility follow the generalized Curie-Weiss law. In the liquid phase, the magnetic susceptibility of these intermetallic compounds above

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

2011-01-01

98

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

99

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

NASA Astrophysics Data System (ADS)

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

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

2009-03-01

100

Magnetoelectric effect of Pb(Zr,Ti)O3 rod arrays in a (Tb,Dy)Fe2/epoxy medium  

NASA Astrophysics Data System (ADS)

We report a kind of multiferroic and multifunctional composite with Pb(Zr,Ti)O3 rod arrays embedded in a ferromagnetic medium of (Tb,Dy)Fe2/epoxy. The composite structure is similar to that of 1-3-type piezoelectric composites with Pb(Zr,Ti)O3 rod arrays embedded in an inert epoxy for already commercial applications as transducers. The large magnetoelectric effect, especially at high frequency at which the electromechanical resonance appears, is observed for such multiferroic composites due to coupling elastic interaction between Pb(Zr,Ti)O3 rods and the ferromagnetic medium, which suggests avenues for designing novel multiferroic materials for practical applications.

Shi, Z.; Nan, C. W.; Zhang, Jie; Cai, N.; Li, J.-F.

2005-07-01

101

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

SciTech Connect

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

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

2009-03-17

102

Magnetic properties of composites of Tb0.28Dy0.72Fe2 and polyvinylidene fluoride  

NASA Astrophysics Data System (ADS)

Bi-ferroic particulate composites with Tb0.28Dy0.72Fe2 (Terfenol-D) particles randomly dispersed in ferroelectric polyvinylidene fluoride matrix prepared by a simple hot-pressing procedure were investigated. With increasing concentration of Terfenol-D, the magnetic susceptibility, saturation magnetization and initial permeability of the composites increases. The dependence of the effective magnetostriction on applied bias for the composites is similar to that for bulk Terfenol-D, but the effective magnetostriction strongly depends on the volume fraction of Terfenol-D. The observed behaviour of the composite is reasonably described by using effective medium theories.

Cai, Ning; Zhai, Jun-Yi; Shi, Zhan; Lin, Yuan-Hua; Nan, Ce-Wen

2004-08-01

103

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

104

Magnetization reversal in exchange-coupled GdFe/TbFe studied by x-ray magnetic circular dichroism  

NASA Astrophysics Data System (ADS)

This work is dedicated to the study of magnetization reversal processes in a ferromagnetically exchange coupled ferrimagnetic/ferrimagnetic bilayer system made of a soft magnetic GdFe layer and a hard TbFe layer. Regular magnetization measurements and x-ray magnetic circular dichroism (XMCD) measurements performed at the ESRF on a GdFe (100 nm)/TbFe (3 nm) bilayer at different temperatures are presented and compared. The XMCD measurements allowed us to study separately the magnetic contribution of Gd, Tb, and Fe at the system interface. Evidence of the creation of an interface domain wall and its compression and pinning are given. In addition to quasistatic measurements, the interface magnetization reversal was also studied using XMCD aftereffect measurements. Both magnetization and XMCD measurements are explained by considering the formation of lateral domains during the interface magnetization reversal.

Mangin, S.; Bellouard, C.; Andrieu, S.; Montaigne, F.; Ohresser, P.; Brookes, N. B.; Barbara, B.

2004-07-01

105

Magnetism of rare-earth--transition-metal nanoscale multilayers. I. Experiments on Dy/Co, Dy/Fe, and Tb/Fe  

SciTech Connect

Experimental investigations of magnetic and structural properties for rare-earth--transition-metal (RE-TM) compositionally modulated films (CMF) are presented in this paper. In particular, {ital A}{sup RE}/{ital B}{sup TM} including {ital A}{sup RE}=Dy and Tb and {ital B}{sup TM}=Fe, Co, and Ni, are studied. The layer thickness and temperature dependence of magnetic properties, which can be interpreted in terms of the antiferromagnetic coupling of RE and TM moments and their atomic distributions, are reported. These {ital A}{sup RE}/{ital B}{sup TM} CMF with nanoscale layer thicknesses exhibit perpendicular magnetic anisotropy (PMA) and the range of the layer thickness required for PMA is determined. The origin of PMA is also discussed.

Shan, Z.S.; Sellmyer, D.J. (Behlen Laboratory of Physics, University of Nebraska-Lincoln, Lincoln, NE (USA) Center for Materials Research Analysis, University of Nebraska-Lincoln, Lincoln, NE (USA))

1990-12-01

106

Hydrothermal synthesis and luminescence properties of uniform BaMoO4:Ln3+ (Ln = Eu, Tb, Dy, and Sm) microspheres  

NASA Astrophysics Data System (ADS)

Uniform and well-dispersed BaMoO4:Ln3+ (Ln = Eu, Tb, Dy, and Sm) microspheres have been successfully synthesized through a facile hydrothermal approach by using trisodium citrate as surfactant. XRD results demonstrate that Ln3+-doped samples can be well indexed to the pure tetragonal scheelite-type BaMoO4, indicating that the Eu3+, Tb3+, Dy3+, and Sm3+ have been effectively doped into the BaMoO4 host lattices. SEM and TEM images indicate that the as-obtained BaMoO4 microspheres consist of tiny packed nanocrystallites. The as-synthesized BaMoO4:Ln3+ (Ln = Eu, Tb, Dy, and Sm) phosphors show strong light emissions with different colors coming from different activator ions under ultraviolet light excitation, which may find potential applications in light phosphor powders and advanced flat panel display devices.

Jia, Guang; Huang, Cuimiao; Li, Lanfen; Wang, Chunzheng; Song, Xingbang; Song, Le; Li, Zheng; Ding, Shiwen

2012-12-01

107

Single crystal growth and properties of incongruently melting TbB{sub 6}, DyB{sub 6}, HoB{sub 6}, and YB{sub 6}  

SciTech Connect

Details of the single crystal growth of incongruently melting TbB{sub 6}, DyB{sub 6}, HoB{sub 6}, and YB{sub 6} using a crucible-free verticle floating zone method are reported. Magnetic susceptibility is reported and discussed. It is suggested that antiferro-quadrupolar ordering occurs in DyB{sub 6} between 30 and 25.6 K.

Takahashi, K.; Kunii, S. [Tohoku Univ., Sendai (Japan)

1997-10-01

108

Structural frustration and occupational disorder: the rare earth metal polysulfides Tb8S(14.8), Dy8S(14.9), Ho8S(14.9), and Y8S(14.8).  

PubMed

Dark red crystals of Y?S(14.8), Tb?S(14.8), Dy?S(14.9), and Ho?S(14.9) have been obtained following different reaction routes. The isostructural title compounds adopt the Gd?Se?? type, a 24-fold superstructure of the ZrSSi-type and can be described in space group A112 (non standard setting of C121, no. 5) with lattice parameter of a = 11.505(1) , b = 15.385(1) , c = 15.726(1) , and ? = 90.21(2) for Y?S(15-x); a = 11.660(1) , b = 15.468(2) , c = 15.844(2) , and ? = 90.19(2) for Tb?S(15-x); a = 11.584(1) , b = 15.340(2) , c = 15.789(2) , and ? = 90.34(2) for Dy?S(15-x); and a = 11.538(1) , b = 15.288(2) , c = 15.740(2) , and ? = 90.23(1) for Ho?S(15-x), respectively. The structure consists of an alternating stacking of puckered [RES] (RE, rare-earth metals) double slabs and planar sulfur layers along [001]. The planar sulfur layers have a complex arrangement of S?? dinuclear dianions, isolated S? ions, and vacancies. All compounds contain trivalent rare-earth metal ions, for Tb?S(15-x) and Dy?S(15-x) antiferromagnetic order was found at T(N) = 5.4(2) K and 3.8(1) K, respectively. Short wavelength cutoff optical band gaps of 1.6 to 1.7 eV were determined. PMID:22136291

Doert, Thomas; Graf, Christian; Vasilyeva, Inga G; Schnelle, Walter

2011-12-02

109

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

2013-01-14

110

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

111

Effect of hydrogen on the magnetic properties of Ho/sub 0. 85/Tb/sub 0. 15/Fe/sub 2/ and Dy/sub 0. 73/Tb/sub 0. 27/Fe/sub 2/  

SciTech Connect

X-ray powder photographs on Ho/sub 0.85/Tb/sub 0.15/Fe/sub 2/H/sub x/ (x = 0--3.1) and Dy/sub 0.73/Tb/sub 0.27/Fe/sub 2/H/sub x/ (x = 0--3.3) revealed that there is an expansion of the lattice upon hydrogenation. Magnetization measurements were performed using a PAR vibrating sample magnetometer in the temperature range 100--700 K. The total magnetic moment is found to decrease with increase of hydrogen content. The Curie temperature of the hydrides is considerably lowered, though the exact T/sub C/ in hydrides could not be determined due to desorption. Both Ho/sub 0.85/Tb/sub 0.15/Fe/sub 2/ and Dy/sub 0.73/Tb/sub 0.27/Fe/sub 2/ do not exhibit any compensation, whereas T/sub comp/ is observed and found to decreasse with x in the case of the Ho/sub 0.85/Tb/sub 0.15/Fe/sub 2/H/sub x/ system, x = 0.18--3.1. No compensation was observed even in the hydrides of the Dy/sub 0.73/Tb/sub 0.27/Fe/sub 2/ system. The temperature variation of magnetization of Ho/sub 0.85/Tb/sub 0.15/Fe/sub 2/H/sub x/ and Dy/sub 0.73/Tb/sub 0.27/Fe/sub 2/H/sub x/ suggests the occurrence of a spin-reorientation transition.

Annapoorni, S.; Markandeyulu, G.; Rama Rao, K.V.S.

1989-06-15

112

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

SciTech Connect

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

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

2009-01-15

113

Temperature dependence of emission and lifetime in Eu(3+)- and Dy(3+)-doped GdVO4.  

PubMed

Eu(3+)- and Dy(3+)-doped GdVO(4) samples synthesized by a high-temperature solid-state method are investigated by fluorescence spectroscopy at 298-750 K. They demonstrate potential for development as thermographic phosphors because the experimental and theoretical temperature dependence of the intensity ratio of the two lines agrees well. Experimental lifetime measurements recorded at 10-750 K were fitted using three theoretical models: multiphonon relaxation, temperature quenching through the charge transfer (CT) region, and our modified CT model (TDCT), which considers the temperature dependence of CT energy. The TDCT model yields the best results with good agreement between experimental and fitted lifetime data. PMID:23478777

Nikoli?, Marko G; Jovanovi?, Dragana J; Drami?anin, Miroslav D

2013-03-10

114

Magnetic susceptibility and parameters of electronic structure of Al 2 REM (Gd, Dy, and Ho) intermetallic compounds at high temperatures  

Microsoft Academic Search

The magnetic susceptibility of Al2REM (REM?=?Gd, Dy, and Ho) intermetallic compounds is experimentally investigated by the Faraday method in a wide temperature\\u000a interval (2902000 K) in different magnetic fields (0.31.3 T). In the crystalline state, the temperature dependences of the\\u000a susceptibility follow the generalized CurieWeiss law. In the liquid phase, the magnetic susceptibility of these intermetallic\\u000a compounds above the melting

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

115

Magnetism and crystal chemistry in REFe sub 12 minus x Ga sub x (RE=Y,Ce,Pr,Nd,Sm,Gd,Tb,Dy,Ho,Er,Tm,Yb,Lu and MM=mischmetal) and (Zr,Pr) (Fe sub 1 minus x Co sub x ) sub 12 minus y Ga sub y  

SciTech Connect

The existence of ternary compounds according to the formula REFe{sub 12{minus}{ital x}} Ga{sub {ital x}} which for {ital x} {approximately}6 represents the iron-rich end of a homogeneous range has been confirmed. X-ray powder analysis of alloys annealed at 800 {degree}C or above generally reveal isotypism with the body- centered tetragonal ThMn{sub 12} -type structure. For the alloys with heavier rare-earth elements from Gd to Lu a phase transition to a body-centered orthorhombic structure type (ScFe{sub 6} Ga{sub 6} type) is observed, which has not been reported before. The transition corresponds to a crystallographic group-subgroup relation ({ital I}4/{ital mmm}{r arrow}{ital t}{sub 2} {r arrow}{ital Immm}), and the transition temperature increases with the ordinal number of the rare earth, indicating the higher the stability of the ScFe{sub 6} Ga{sub 6} -type structure, the smaller the radius of the rare-earth element. Accordingly, the ThMn{sub 12} -type structure is stable for the early rare-earth members and no transition was observed as low as 400 {degree}C. From magnetization curves it is shown that for REFe{sub 12{minus}{ital x}} Ga{sub {ital x}} (RE=rare earth, Y) all magnetic sublattices order simultaneously at temperatures above {Tc} {approximately}400 K. For Y, Lu, and light rare-earth-containing alloys collinear or canted ferromagnetism is observed. The vector of magnetization was found to be close to the {ital a},{ital b} plane. Strong hysteresis effects are revealed in all alloys. Energy products are highest for (Pr,Sm)Fe{sub {approximately}6}Ga{sub {approximately}6}. For the compounds with the heavy rare-earth elements a ferrimagnetic behavior is encountered. Both magnetic sublattices, i.e., Fe and RE, couple antiparallel, exhibiting easy plane anisotropy. The crystallographic transformation, tetragonal-orthorhombic, has little effect on the magnetic behavior of these alloys.

Weitzer, F.; Hiebl, K.; Rogl, P.; Grin, Y.N. (Institute of Physical Chemistry, University of Vienna, A-1090 Wien, Waehringerstrasse 42 (Austria))

1990-10-01

116

Anisotropic magnetization and resistivity of single crystalline RNi1-xBi2 y (R = La-Nd, Sm, Gd-Dy)  

SciTech Connect

We present a detailed study of RNi1?xBi2y (R = LaNd, Sm, GdDy) single crystals by measurements of stoichiometry and temperature dependent magnetic susceptibility, magnetization, and electrical resistivity. This series forms with partial Ni occupancy, 0.72 ? (1?x) ? 0.84, as well as a variable Bi occupancy, 1.76 ? (2y) ? 2.14. For R = CeNd, GdDy, the RNi1?xBi2y compounds show local-moment like behavior and order antiferromagnetically at low temperatures. Determination of anisotropies as well as antiferromagnetic ordering temperatures for RNi1?xBi2y (R = CeNd, Sm, GdDy) have been made. Crystalline samples from this family exhibit minority, second phase superconductivity at low temperatures, which can be associated with NiBi and Bi contamination. No evidence of bulk superconductivity has been observed.

Lin, Xiao [Iowa State University; Straszheum, Warren E. [Ames Laboratory; Budko, Sergey L. [Ames Laboratory; Canfield, Paul C. [Ames Laboratory

2012-11-29

117

Studies on the Decay of sup 160 Tb to Levels in sup 160 Dy by Ge(Li)-Ge(Li) Coincidence System.  

National Technical Information Service (NTIS)

This work is concerned with the study of the energy levels and the properties of gamma-ray transitions in sup 160 Dy, resulting from the BETA-decay of the parent radioactive isotope sup 160 Tb (72 d.). These studies have been done by means of, single and ...

A. M. Hassan M. A. Abou-Zeid M. Mekamer

1981-01-01

118

X-ray diffraction and extended X-ray absorption fine-structure study of RMn 2 hydrides (R = Y, Gd or Dy)  

Microsoft Academic Search

Structural properties of RMn2 hydrides (R = Y, Gd or Dy) have been studied by means of powder X-ray diffraction (XRD) at 300 K and extended X-ray absorption fine structure (EXAFS) at 300 K and low temperatures. It was found that at 300 K the lattice parameters increase continuously upon hydrogen absorption (except for DyMn2Hx with x < 1) and

J. Przewo?nik; V. Paul-Boncour; M. Latroche; A. Percheron-Gugan

1996-01-01

119

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

120

Lifetime measurements of superdeformed bands in {sup 148{endash}149}Gd and {sup 152}Dy: Evidence for structure-dependent elongations  

SciTech Connect

Precise level lifetimes have been measured for various superdeformed bands in {sup 148,149}Gd and {sup 152}Dy with the Doppler-shift attenuation method. From the derived quadrupole moments, {ital Q}{sub 0}, we find large differences in deformation between the yrast bands and some excited bands in the gadolinium isotopes. Moreover, two of the excited Gd bands and the {sup 152}Dy yrast band, which have identical moments of inertia, have different elongations, supporting the picture that alignment and deformation effects cancel in identical bands. {copyright} {ital 1996 The American Physical Society.}

Savajols, H.; Korichi, A.; Ward, D.; Appelbe, D.; Ball, G.; Beausang, C.; Beck, F.; Byrski, T.; Curien, D.; Dagnall, P.; de France, G.; Disdier, D.; Duchene, G.; Erturk, S.; Finck, C.; Flibotte, S.; Gall, B.; Galindo-Uribarri, A.; Haas, B.; Hackman, G.; Janzen, V.; Kharraja, B.; Lisle, J.; Merdinger, J.; Mullins, S.; Pilotte, S.; Prevost, D.; Radford, D.; Rauch, V.; Rigollet, C.; Smalley, D.; Smith, M.; Stezowski, O.; Styczen, J.; Theisen, C.; Twin, P.; Vivien, J.; Waddington, J.; Zuber, K.; Ragnarsson, I. [Centre de Recherches Nucleaires, IN2P3-CNRS/Universite Louis Pasteur, F-67037 Strasbourg Cedex 2 (France)]|[Institut de Physique Nucleaire, IN2P3-CNRS, Bat.104, F-91406 Orsay Cedex (France)]|[AECL, Chalk River Laboratories, Chalk River, Ontario, Canada KOJ 1J0]|[Oliver Lodge Laboratory, University of Liverpool, Liverpool L693BX (United Kingdom)]|[Schuster Laboratory, University of Manchester, Manchester M139PL (United Kingdom)]|[Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1 (CANADA)]|[Institute of Nuclear Physics, PL31-342, Krakow (Poland)]|[Department of Mathematical Physics, Lund Institute of Technology, Box 118, S-221 00 Lund (Sweden)

1996-06-01

121

Efficient three-photon luminescence with strong polarization dependence from a scintillating silicate glass co-doped with Gd3+ and Tb3+.  

PubMed

Efficient three-photon luminescence (3PL) from a scintillating silicate glass co-doped with Gd(3+) and Tb(3+) was generated by using a focused femtosecond laser beam at 800 nm. Four emission bands centered at 496, 541, 583, and 620 nm were identified as the electronic transitions between the energy levels of Tb(3+) followed by three-photon absorption (3PA) in Gd(3+) and Tb(3+) and the resonant energy transfer from Gd(3+) to Tb(3+). More interestingly, a strong polarization dependence of the 3PL was observed and it is ascribed to the polarization dependent 3PA in Gd(3+) and Tb(3+) and/or the angular distribution of photogenerated electrons in the glass. PMID:23482170

Li, Guang-Can; Zhang, Cheng-Yun; Deng, Hai-Dong; Liu, Guang-Yin; Lan, Sheng; Qian, Qi-; Yang, Zhong-Min; Gopal, Achanta Venu

2013-03-11

122

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

SciTech Connect

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

Miletic, G.I. [Laboratory for Solid State Chemistry, Division of Materials Chemistry, Institute Rudjer Boskovic, P.O. Box 180, 10002 Zagreb (Croatia)], E-mail: gmiletic@irb.hr; Blazina, Z. [Laboratory for Solid State Chemistry, Division of Materials Chemistry, Institute Rudjer Boskovic, P.O. Box 180, 10002 Zagreb (Croatia)

2007-02-15

123

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

PubMed

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

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

2010-04-19

124

High-pressure preparation, crystal structure, magnetic properties, and phase transitions in GdNiO{sub 3} and DyNiO{sub 3} perovskites  

SciTech Connect

Strongly distorted RNiO{sub 3}(R = Gd, Dy) perovskites, containing Ni{sup 3+}, have been prepared under high-pressure conditions: 90 MPa of O{sub 2} pressure (R = Gd) or 2 GPa of hydrostatic pressure in the presence of KClO{sub 4} (R = Dy). These materials have been characterized by X-ray diffraction, neutron powder diffraction (NPD) (for DyNiO{sub 3}), DSC, magnetic measurements, and specific heat measurements. In contrast with the next member of the series, HoNiO{sub 3}, which shows a subtle monoclinic distortion at room temperature, DyNiO{sub 3} exhibits orthorhombic symmetry, as shown by NPD data. A noticeable distortion is observed in NiO{sub 6} octahedra, at variance with the almost regular octahedra exhibited by the first members (R = La, Pr, Nd) of the series: it is interpreted as a manifestation of the Jahn-Teller character of the Ni{sup 3+} cation, enhanced in the RNiO{sub 3} perovskites with heavier rare earths, showing weaker, less covalent Ni-O bonds. DSC measurements show sharp endothermic peaks at 510.9 K (Gd) and 564.1 K (Dy) in the heating run, which have been assigned to the corresponding metal-insulator transitions of both charge-transfer perovskites, based on the analogous behavior observed for the precedent members of the RNiO{sub 3} series. Subtle slope variations in the susceptibility vs T curves, highly dominated by the strong paramagnetic signal of Gd{sub 3+} and Dy{sup 3+}, indicate the onset of antiferromagnetic ordering of the Ni{sup 3+} sublattice, confirmed by specific heat measurements, below T{sub N} values of 185 and 154 K, respectively. Additionally, the Dy{sup 3+} sublattice becomes ordered below 8 K.

Alonso, J.A.; Martinez-Lope, M.J.; Casais, M.T.; Martinez, J.L.; Demazeau, G.; Largeteau, A.; Garcia-Munoz, J.L.; Munoz, A.; Fernandez-Diaz, M.T.

1999-09-01

125

Specific features of Eu 3+ and Tb 3+ magnetooptics in gadolinium-gallium garnet (Gd 3Ga 5O 12)  

Microsoft Academic Search

We reported magnetooptical properties of Eu3+(4f(6)) and Tb3+(4f(8)) in single crystals of Gd3Ga5O12 (GGG), Y3Ga5O12 (YGG), and Eu3+(4f(6)) in Eu3Ga5O12 (EuGG) for both ions occupying sites of D2 symmetry in the garnet structure. Absorption, luminescence, and magnetic circular polarization of luminescence (MCPL) spectra of Tb3+ in GGG and YGG and absorption and magnetic circular dichroism (MCD) of Eu3+ in EuGG

Uygun V. Valiev; John B. Gruber; Dejun FU; Vasiliy O. Pelenovich; Gary W. Burdick; Mariya E. Malysheva

2011-01-01

126

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

NASA Astrophysics Data System (ADS)

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

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

2001-03-01

127

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

SciTech Connect

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

Alexander S. Chernyshov

2006-08-09

128

Size Variation of Tb-DOPED Gd2O3 Nanoparticles Studied by X-Ray Excited Luminescence and Diffraction  

Microsoft Academic Search

Post-fabrication heat treatment has been found as an effective means for controlling the size distribution of Tb-doped Gd2O3 nanoparticles. Variations in the electronic structure and structural order of these doped quantum dots are investigated by using the techniques of X-ray excited luminiscence and diffraction. From room temperature to 1000C X-ray powder diffraction of this nanoparticle system shows a three-stage transition

Y. L. Soo; S. W. Huang; Y. H. Kao; Y. W. Yang; L. J. Lai; V. Chhabra; B. Kulkami; J. V. D. Veliadis; R. N. Bhargava

2001-01-01

129

Phonon Raman scattering of RCrO3 perovskites (R=Y, La, Pr, Sm, Gd, Dy, Ho, Yb, Lu)  

NASA Astrophysics Data System (ADS)

We report a systematic investigation of orthorhombic perovskite-type RCrO3 powder samples by Raman scattering for nine different rare earth R3+ cations (R = Y, La, Pr, Sm, Gd, Dy, Ho, Yb, and Lu). The room-temperature Raman spectra and the associated phonon mode assignment provide reference data for structural investigation of the whole series of RCrO3 orthochromites and phonon ab-initio calculations. The assignment of the chromite spectra and comparison with Raman data on other orthorhombic perovskites allows correlating the phonon modes with the structural distortions in the RCrO3 series. In particular, two Ag modes are identified as octahedra rotation soft modes, as their positions scale linearly with the octahedra tilt angle of the CrO6 octahedra.

Weber, M. C.; Kreisel, J.; Thomas, P. A.; Newton, M.; Sardar, K.; Walton, R. I.

2012-02-01

130

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

NASA Astrophysics Data System (ADS)

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

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

2011-08-01

131

Pressure-induced structural and vibrational evolution in ferroelectric RInO3 (R=Eu, Gd, Dy)  

NASA Astrophysics Data System (ADS)

The structural and vibrational properties of the hexagonal indates RInO3 (R=Eu, Gd and Dy) have been studied under high pressures using synchrotron x-ray diffraction and Raman scattering in diamond anvil cells. The three hexagonal structures exhibit anisotropic compression behaviors under high pressures and are stable up to ~17 GPa. High-pressure Raman spectra show that most frequencies harden linearly with different rates under high pressures. At ~17 GPa, three compounds undergo similar phase transitions. It is hard to indentify the structure of the high-pressure phase due to the broad x-ray diffraction and Raman patterns which could result from the kinetic hindrance of the phase transition at room temperature.

Lin, Chuanlong; Liu, Jing; Li, Yanchun; Li, Xiaodong; Li, Rui

2013-11-01

132

Magnetoelasticity of Tb0.3Dy0.7Fe1.95 alloys in a multiaxial stress-magnetic field space  

Microsoft Academic Search

The simultaneous measurements of magnetization and magnetostriction have been carried out for Tb0.3Dy0.7Fe1.95 alloys subjected to the multiaxially magnetomechanical loading. The saturated magnetization and magnetostriction both decrease with the increase of the angle between the applied stress and magnetic filed. The magnetostriction goes up to a climax and then decreases as the applied magnetic field increases, which should remain saturated

Yongmao Pei; Daining Fang; Xue Feng

2007-01-01

133

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

Microsoft Academic Search

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

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

1996-01-01

134

Messung des g R -Faktors des 2+-Rotationsniveaus von Dy 160 nach der Spinrotationsmethode und Bestimmung der Multipolmischungen mehrerer ?-bergnge im Zerfall des Tb 160  

Microsoft Academic Search

A differential measurement of the spin rotation of Dy160 in the 2+ rotational state was performed by using liquid sources of TbCl3 solved in 3M HCl and applying an external magnetic field of 33 500 Gauss. No change of the Larmor precession frequency could be detected within the first 1010?9 s. It is concluded that the ground state of the

C. Gnther; G. Strube; U. Wehmann; W. Engels; H. Blumberg; H. Luig; R. M. Lieder; E. Bodenstedt; H. J. Krner

1965-01-01

135

Messung des gR-Faktors des 2+-Rotationsniveaus von Dy160 nach der Spinrotationsmethode und Bestimmung der Multipolmischungen mehrerer gamma-bergnge im Zerfall des Tb160  

Microsoft Academic Search

A differential measurement of the spin rotation of Dy160 in the 2+ rotational state was performed by using liquid sources of TbCl3 solved in 3 M HCl and applying an external magnetic field of 33 500 Gauss. No change of the Larmor precession frequency could be detected within the first 1010-9 s. It is concluded that the ground state of

C. Gnther; G. Strube; U. Wehmann; W. Engels; H. Blumberg; H. Luig; R. M. Lieder; E. Bodenstedt; H. J. Krner

1965-01-01

136

Luminescence of NaGdFPO{sub 4}:Ln {sup 3+} after VUV excitation: A comparison with GdPO{sub 4}:Ln {sup 3+} (Ln=Ce, Tb)  

SciTech Connect

The phosphors NaGdFPO{sub 4}:Ln {sup 3+} and GdPO{sub 4}:Ln {sup 3+} (for Ln{sup 3+}=Ce{sup 3+} and Tb{sup 3+}) were prepared by solid-state reaction technique, the VUV-vis spectroscopic properties of the phosphors were investigated, and we vividly compare the luminescence of Ce{sup 3+} and Tb{sup 3+} in the hosts. For phosphors GdPO{sub 4}:Ln {sup 3+}, the band near 155 nm in VUV excitation spectrum is assumed to be the host-related absorption, and for NaGdFPO{sub 4}:Ln {sup 3+} the absorption is moved to longer wavelength, near 170 nm, showing the P-O bond covalency increased after fluoridation. The f-d transitions of Ce{sup 3+} and Tb{sup 3+} in the host lattices are assigned and corroborated, and it was found that the 5d states are with lower energy in NaGdFPO{sub 4}:Ln {sup 3+} than those in GdPO{sub 4}:Ln {sup 3+}. For fluoridation of GdPO{sub 4}:Ln {sup 3+} to NaGdFPO{sub 4}:Ln {sup 3+}, the energy change of Ln {sup 3+} (Ln=Ce, Tb) 5d states is consistent with that of host-related absorption.

Tian Zifeng [State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Liang Hongbin [State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China)]. E-mail: cesbin@mail.sysu.edu.cn; Lin Huihong [State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Su Qiang [State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Guo Bei [State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Zhang Guobin [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026 (China); Fu Yibing [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026 (China)

2006-05-15

137

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

SciTech Connect

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

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

2012-02-27

138

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

NASA Astrophysics Data System (ADS)

Alkaline earth metal molybdates are promising candidates as a host material for high efficiency narrow spectral emission phosphors. These phosphors could potentially be used for the fabrication of phosphor-converted light emitting diodes (pc-LEDs). Phosphor crystals of calcium molybdate doped with rare earth dopant Ln3+(Ln=Eu, Dy, Tb) grown using flux growth method have been shown to exhibit higher excitation efficiency than the powders synthesized by solid-state reaction process. Molybdenum (VI) oxide has been found to be a suitable flux for growing large size optically transparent high quality crystals at a temperature around 1100 C. Using the excitation wavelengths of 465 nm, 454 nm and 489 nm for CaMoO4: Eu3+, CaMoO4: Dy3+ and CaMoO4: Tb3+, respectively, intense emission lines at wavelengths of 615 nm, 575 nm and 550 nm were observed. The optimized doping concentrations of 12%, 2% and 5% for Eu3+, Dy3+ and Tb3+, respectively, provided the highest luminescence intensity.

Khanna, A.; Dutta, P. S.

2013-02-01

139

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

NASA Astrophysics Data System (ADS)

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

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

2005-11-01

140

Phase relations and linear thermal expansion of cubic solid solutions in the Th1-xMxO2-x/2 (M = Eu, Gd, Dy) systems  

NASA Astrophysics Data System (ADS)

Cell parameters and linear thermal expansion studies of the Th M oxide systems with general compositions Th1-xMxO2-x/2 (M = Eu3+, Gd3+ and Dy3+, 0.0 ? x ? 1.0) are reported. The XRD patterns of each product were refined to specify the solid solubility limits of MO1.5 in the ThO2 lattice. The upper solid solubility limits of EuO1.5, GdO1.5 and DyO1.5 in the ThO2 lattice under conditions of slow cooling from 1673 K are represented as Th0.50Eu0.50O1.75, Th0.60Gd0.40O1.80 and Th0.85Dy0.15O1.925, respectively. The linear thermal expansion (293 1123 K) of MO1.5 and their single-phase solid solutions with thoria were investigated by dilatometery. The average linear thermal expansion coefficients (?) of the compounds decrease on going from EuO1.5 to DyO1.5. The values of ? for EuO1.5, GdO1.5 and DyO1.5 containing solid solutions showed a downward trend as a function of the dopant concentration. The linear thermal expansion (293 1473 K) of the solid solutions investigated by high-temperature XRD also showed a similar trend.

Mathews, M. D.; Ambekar, B. R.; Tyagi, A. K.

2005-05-01

141

Specific heat anomalies in the magnetic borocarbide superconductors Y1-xRxNi2B2C (R=Gd, Dy, Ho, and Er)  

Microsoft Academic Search

The specific heat anomalies associated with the superconducting transition of Y1-xRxNi2B2C (R=Gd, Dy, Ho, and Er) show a common correlation between the specific heat jump DeltaC and the transition temperature Tc with an almost quadratic relation DeltaC~T2c in all these solid solutions. The antiferromagnetic superconductor DyNi2B2C with TN>Tc as well as Ho and ErNi2B2C, which are paramagnetic at Tc, fit

M. El-Hagary; H. Michor; G. Hilscher

2000-01-01

142

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

NASA Astrophysics Data System (ADS)

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

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

2009-10-01

143

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

144

Ln(III)2Mn(III)2 heterobimetallic "butterfly" complexes displaying antiferromagnetic coupling (Ln = Eu, Gd, Tb, Er).  

PubMed

The isostructural heterometallic complexes [Ln(III)(2)Mn(III)(2)O(2)(ccnm)(6)(dcnm)(2)(H(2)O)(2)] (Ln = Eu (1Eu), Gd (1Gd), Tb (1Tb), Er (1Er); ccnm = carbamoylcyanonitrosomethanide; dcnm = dicyanonitrosomethanide) have been synthesised and structurally characterised. The in situ transition metal promoted nucleophilic addition of water to dcnm, forming the derivative ligand ccnm, plays an essential role in cluster formation. The central [Ln(III)(2)Mn(III)(2)(O)(2)] moiety has a "butterfly" topology. The coordinated aqua ligands and the NH(2) group of the ccnm ligands facilitate the formation of a range of hydrogen bonds with the lattice solvent and neighbouring clusters. Magnetic measurements generally reveal weak intracluster antiferromagnetic coupling, except for the large J(MnMn) value in 1Gd. There is some evidence for single molecule magnetic (SMM) behaviour in 1Er. Comparisons of the magnetic properties are made with other recently reported butterfly-type {Ln(III)(x)M(III)(4-x) (d-block)} clusters, x = 1, 2; M = Mn, Fe. PMID:22885927

Chesman, Anthony S R; Turner, David R; Berry, Kevin J; Chilton, Nicholas F; Moubaraki, Boujemaa; Murray, Keith S; Deacon, Glen B; Batten, Stuart R

2012-08-13

145

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

SciTech Connect

The author has studied the diagonal and off-diagonal optical conductivity of RFe{sub 2}(R = Gd, Tb, Ho, Lu) and GdCo{sub 2} single crystals grown by the flux method. Using spectroscopic ellipsometry the author has measured the dielectric function from 1.5 to 5.5 eV. The magneto-optical Kerr spectrometer at temperatures between 7 and 295 K and applied magnetic fields between 0.5 to 1.6 T. The apparatus and calibration method are described in detail. Using magneto-optical data and optical constants he derives the experimental value of the off-diagonal conductivity components. Theoretical calculations of optical conductivities and magneto-optical parameters were performed using the tight binding-linear muffin tin orbitals method within the local spin density approximation. He applied this TB-LMTO method to LuFe{sub 2}. The theoretical results obtained agree well with the experimental data. The oxidation effects on the diagonal part of the optical conductivity were considered using a three-phase model. The oxidation effects on the magneto-optical parameters were also considered by treating the oxide layer as a nonmagnetic thin transparent layer. These corrections change not only the magnitude but also the shape of the optical conductivity and the magneto-optical parameters.

Lee, S.J.

1999-02-12

146

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

Microsoft Academic Search

The potassium lanthanide double sulphates KLn(SO4)2H2O (Ln=La, Nd, Sm, Eu, Gd, Dy) were obtained by evaporation of aqueous reaction mixtures of rare earth (III) sulphates and potassium thiocyanate at 298K. X-ray single-crystal investigations show that KLn(SO4)2H2O (Ln=Nd, Sm, Eu, Gd, Dy) crystallise monoclinically (Ln=Sm: P21\\/c, Z=4, a=10.047(1), b=8.4555(1), c=10.349(1), wR2=0.060, R1=0.024, 945 reflections, 125 parameters) while KLa(SO4)2H2O adopts space group

Karolina Kazmierczak; Henning A. Hppe

2010-01-01

147

Syntheses, crystal structures and vibrational spectra of KLn(SO4)2H2O (Ln=La, Nd, Sm, Eu, Gd, Dy)  

Microsoft Academic Search

The potassium lanthanide double sulphates KLn(SO4)2H2O (Ln=La, Nd, Sm, Eu, Gd, Dy) were obtained by evaporation of aqueous reaction mixtures of rare earth (III) sulphates and potassium thiocyanate at 298 K. X-ray single-crystal investigations show that KLn(SO4)2H2O (Ln=Nd, Sm, Eu, Gd, Dy) crystallise monoclinically (Ln=Sm: P21\\/c, Z=4, a=10.047(1), b=8.4555(1), c=10.349(1) , wR2=0.060, R1=0.024, 945 reflections, 125 parameters) while KLa(SO4)2H2O adopts

Karolina Kazmierczak; Henning A. Hppe

2010-01-01

148

X-ray powder diffraction and vibrational spectra studies of rare earth borophosphates LnO(BO)(PO) (Ln = La, Nd, Gd, and Dy)  

Microsoft Academic Search

The crystal structure of the isomorphical rare earth borophosphate compounds, LnO(BO)(PO) (Ln = La, Nd, Gd and Dy), has been studied by a combination of X-ray powder diffraction (XRD) and vibration spectroscopic techniques. The Raman and infrared spectra of these compounds have been investigated, and their interpretation is discussed on both theoretical and experimental bases. Assignments have been deduced from

Ying Shi; Hao Zhang; Jinling Yang

1997-01-01

149

Effect of hygroscopic nature on the electrical characteristics of lanthanide oxides (Pr2O3, Sm2O3, Gd2O3, and Dy2O3)  

Microsoft Academic Search

The hygroscopic nature of lanthanide oxides such as Pr2O3, Sm2O3, Gd2O3, and Dy2O3 was characterized by means of x-ray photoelectron spectroscopy and its effect on the electrical characteristics of the compounds was investigated. Among the four samples, Pr2O3 was found to be the most reactive with water which can be attributed to the relatively large ionic radius and lower electronegativity

Sanghun Jeon; Hyunsang Hwang

2003-01-01

150

Magnetic susceptibility and parameters of electronic structure of Al2R (R = La, Ce, Sm, Gd, Dy, Ho, Yb) intermetallic compounds at high temperatures  

Microsoft Academic Search

Magnetic properties of intermetallic compounds Al2R (R = La, Ce, Sm, Gd, Dy, Ho, Yb) are investigated in a wide temperature (20-1650C) and magnetic fields (0,3-1,3 T) ranges. For all the samples the increase of magnetic susceptibility with temperature growth was found in liquid state. From experimental data several parameters of electronic structure of the compounds were obtained. In particular,

N. Uporova; S. Uporov; V. Sidorov; K. Shunyaev; R. Zakharov; S. Petrova

2011-01-01

151

Mssbauer studies of magnetic behavior of 3d-doped REBa2Cu3- x Fe x O7+delta (RE=Y, Er, Dy, Gd)  

Microsoft Academic Search

A Mssbauer study has been made on57Fe ions substituted into the Cu(1) site of REBa2Cu3- x Fe x O7+delta (RE=Y, Er, Dy, Gd; x=0.15, 0.30). At low temperature, the iron atoms antiferromagnetically order with a transition temperature which is dependent on the Fe concentration. The temperature dependence of the magnetic subspectra representing Fe ions with various local oxygen environments in

C. W. Kimball; B. Dabrowski; Yuehai Liang; Weimin Peng; B. D. Dunlap

1992-01-01

152

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

SciTech Connect

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

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

2012-01-01

153

Anisotropic perpendicular axis magnetostriction in twinned Tb sub x Dy sub 1 minus x Fe sub 1. 95  

SciTech Connect

The longitudinal magnetostriction ({Delta}{ital l}/{ital l}) for twinned Tb{sub {ital x}}Dy{sub 1{minus}{ital x}}Fe{sub 1.95} material, prepared by the free-standing float-zone method, has been previously measured and found to be very large (2000{times}10{sup {minus}6}) at room temperature. The magnetostrictions for the (111) and (1{bar 1}0) crystallographic axes perpendicular to the applied stress and magnetic-field (11{bar 2}) direction are presented as functions of temperature, applied stress, and applied magnetic field. The temperature range is {plus minus}60 {degree}C centered about the anisotropy compensation temperature of Terfenol-D (+10 {degree}C). The stress ranges from 2 to 32 MPa and the magnetic field to {plus minus}2000 Oe. The temperature dependence of the perpendicular axes magnetostriction is similar to that of the conventional magnetostriction measured parallel to the (11{bar 2}) growth axis. Relative values for the saturation magnetostriction exhibit a large anisotropy in the perpendicular direction, ranging from {minus}117% for the (111) to +19% for the (1{bar 1}0) direction. This ratio stays constant as a function of temperature above the compensation temperature for a given prestress above 8 MPa. The largest absolute value of magnetostriction (2260{times}10{sup {minus}6}) occurs in the (111) direction at 10 {degree}C at a prestress pressure of 12 MPa. Above this temperature the magnetostriction falls at a rate of {minus}8.5{times}10{sup {minus}6}/{degree}C. The volume magnetostriction is shown to be small and highly sample dependent. All data is consistent with the parent-twin magnetization model and also the magnetostriction values along nonprincipal axes.

Teter, J.P.; Wun-Fogle, M.; Clark, A.E.; Mahoney, K. (Naval Surface Warfare Center, R45, 10901 New Hampshire Avenue, Silver Spring, Maryland 20903-5000 (USA))

1990-05-01

154

Domain observation and magnetostriction in Tb sub 0. 3 Dy sub 0. 7 Fe sub 2 twinned single crystals  

SciTech Connect

The ternary alloy Tb{sub 0.3}Dy{sub 0.7}Fe{sub 2} (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 Fe{sub 3}). A bar with (111) and (1{bar 1}0) faces perpendicular to the (11{bar 2}) growth direction was examined. Also, a (11{bar 1}) slab was cut from the boule. This slab was studied along the (11{bar 1}) and (1{bar 1}0) directions with prestress applied along the (11{bar 1}). This is the first report of the effects of applying prestress and magnetic fields in a direction not collinear with the (11{bar 2}) growth direction. From magnetization ({ital M}) and magnetostriction ({lambda}) measurements as a function of field, prestress, and temperature, we determined the hysteresis and saturation parameters. These measurements do not indicate the (1{bar 1}0) {lambda} and {ital 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 (11{bar 1}) 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 (1{bar 1}0) bar faces and on the (11{bar 1}) slab correlate with each other with respect to orientations and domain interpretations.

Teter, J.P.; Mahoney, K. (Naval Surface Warfare Center, 10901 New Hampshire Avenue, Silver Spring, Maryland 20903-5000 (USA)); Al-Jiboory, M.; Lord, D.G. (Department of Pure and Applied Physics, University of Salford, Salford M5-4WT, (United Kingdom)); McMasters, O.D. (Edge Technologies, Ames, Iowa 50011 (USA))

1991-04-15

155

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

SciTech Connect

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

Li, Xue; Yu, Min [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Department of Chemistry, Northeast Normal University, Changchun 130024 (China); Hou, Zhiyao; Li, Guogang; Ma, Ping'an; Wang, Wenxin; Cheng, Ziyong [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Lin, Jun, 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)

2011-01-15

156

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

NASA Astrophysics Data System (ADS)

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

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

2011-07-01

157

Magnetization, resistivity and heat capacity of the anisotropic RVSb3 crystals (R = La-Nd, Sm, Gd-Dy)  

SciTech Connect

Single crystals of rare-earth vanadium triantimonides RVSb{sub 3}, with R = La-Nd, Sm and Gd-Dy are grown out of solution. The substitution of heavier rare-earths makes the orthorhombic structure contract and accompanies changes in the magnetic properties throughout the series. Characterization of RVSb{sub 3} family was made with single-crystal X-ray diffraction, temperature and field-dependent magnetization M(T, H), heat capacity C(T) and resistivity {rho}(T). All of the compounds are metallic, and all, with the exceptions of non-magnetic LaVSb{sub 3} and ferromagnetic CeVSb{sub 3}, show features typical of antiferromagnetic order. Thermodynamic and transport measurements indicate that these materials are highly anisotropic magnetically, due to the crystal electric field splitting of the Hund's ground state, but only manifest a moderate electrical anisotropy. Given the relative scarcity of Ce-based ferromagnets, the temperature-dependent magnetization of CeVSb{sub 3} was measured under applied hydrostatic pressure up to 10 kbar, and T{sub c} increases at the rate of 0.14(1) K kbar{sup -1}.

Sefat, A.; Bud'ko, S.; Canfield, P.

2007-05-25

158

Entropy changes and the caloric effects in R5Si2Ge2 (R=Gd and Tb)  

NASA Astrophysics Data System (ADS)

It has been experimentally shown that at ambient pressure, the compound Gd5Si2Ge2 undergoes a first order transition with giant magnetocaloric effect around this room temperature. Experimental data also show that an applied pressure increases the critical temperature of this compound and keeps the first order phase transition. On the other hand, experimental data show that the compound Tb5Si2Ge2 undergoes a second order phase transition with a normal magnetocaloric effect around 100 K. It has also been shown that an applied pressure increases its critical temperature without changing the order of the phase transition. In this work, we calculate the magnetocaloric and barocaloric effects in and Gd5Si2Ge2 and Tb5Si2Ge2. For this purpose, we use a model of localized magnetic moments including the magnetoelastic interaction. In the model, the order of the phase transition is controlled by the ratio between the exchange interaction and the magnetoelastic coupling parameter. Our calculations show that these compounds exhibit large values of the entropy changes upon pressure variation in good agreement with the available experimental data.

de Oliveira, Nilson

2013-03-01

159

Magnetization, Young's moduli, and magnetostriction of rare-earth-iron eutectic alloys with R = Tb0.6Dy0.4  

Microsoft Academic Search

Rare-earth-iron alloys, R0.9Fe0.1, R0.72Fe0.28, and R0.42Fe0.58 (R = Tb0.6Dy0.4), containing the R\\/RFe2 eutectic composition were prepared by Bridgman and free-standing zone-melting techniques. Magnetization measurements were made in fields up to 800 kA\\/m between 55 and 300 K. A huge increase in magnetization below 210 k occurs as the R component becomes ordered. At low applied magnetic fields there is clear

A. E. Clark; M. Wun-Fogle; J. P. Teter; J. B. Restorff; S. F. Cheng

1994-01-01

160

Magnetization, Youngs moduli, and magnetostriction of rare-earthiron eutectic alloys with R=Tb0.6Dy0.4  

Microsoft Academic Search

Rare-earthiron alloys, R0.9Fe0.1, R0.72Fe0.28, and R0.42Fe0.58 (R=Tb0.6Dy0.4), containing the R\\/RFe2 eutectic composition were prepared by Bridgman and free-standing zone-melting techniques. Magnetization measurements were made in fields up to 800 kA\\/m between 55 and 300 K. A huge increase in magnetization below 210 K occurs as the R component becomes ordered. At low applied magnetic fields there is clear identification of

A. E. Clark; M. Wun-Fogle; J. P. Teter; J. B. Restorff; S. F. Cheng

1994-01-01

161

Structure and magnetic properties of ScFe 6Ga 6-type RCo 5Ga 7 ( R=Y, Tb, Dy, Ho and Er)  

Microsoft Academic Search

The structure and magnetic properties of the RCo5Ga7 (R=Y, Tb, Dy, Ho and Er) compounds with the ScFe6Ga6-type structure have been studied. The stability of RCo5Ga7 is closely related with the ratio of the metal radii RRE\\/R(Co,Ga). With RRE\\/R(Co,Ga)?1.36, the compounds can be stabilized in the ScFe6Ga6-type structure. The lattice of RCo5Ga7 shrinks as the atomic order of R increases,

Hong Chang; Yong-quan Guo; Lin-tao Yang; Quan-lin Liu; Wei-cun Feng; Jing-kui Liang; Guang-hui Rao

2004-01-01

162

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

SciTech Connect

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

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

2010-12-01

163

Thermoluminescence properties of isostructural K2YF5 and K2GdF5 crystals doped with Tb3+ in response to ?, ? and X-ray irradiation  

NASA Astrophysics Data System (ADS)

The thermoluminescence (TL) properties of isostructural fluoride K2YF5 and K2GdF5 crystals doped with Tb3+ of different concentrations have been studied in the temperature range from 30 to 500 C after ?, ? and X-ray irradiation. Strongly different structures of TL glow curves following ? or ? irradiation have been found for Tb3+ doped K2YF5 for all studied concentrations of Tb3+ whereas for K2GdF5 crystals the different TL curves after ? or ? irradiation are detected only for heavily doped samples. On the other hand, all the studied materials show similar TL glow curves after ? or X-ray irradiation. It has been discovered that K2YF5 doped with 1 at.% Tb3+ has TL radiation sensitivity to ? irradiation of the same order as that of the well known TLD-100 (LiF:Mg,Ti) phosphor and much higher sensitivity to ? irradiation. The TL mechanism in K2YF5 and K2GdF5 doped with Tb3+ is discussed by taking into account the TL emission spectra from irradiated samples, which are identical to the emission spectra of the Tb3+ ions in these hosts under photo-excitation, and the kinetics parameters obtained with the method of various heating rates.

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

2010-10-01

164

sup 57 Fe Mossbauer studies on Ho sub 0. 85 Tb sub 0. 15 Fe sub 2 H sub x and Dy sub 0. 73 Tb sub 0. 27 Fe sub 2 H sub x  

SciTech Connect

{sup 57}Fe Mossbauer measurements were carried out on Ho{sub 0.85}Tb{sub 0.15}Fe{sub 2}H{sub {ital x}} ({ital x}=0--3.1) and Dy{sub 0.73}Tb{sub 0.27}Fe{sub 2}H{sub {ital x}} ({ital x}=0--3.3) in the temperature range 105--360 K. The hyperfine field at the iron site was found to increase slightly with increasing hydrogen concentration in both the systems. The temperature variation studies of the hyperfine fields, the quadrupole coupling constant and the isomer shift suggest the occurance of spin reorientation. The isomer shift studied as a function of concentration indicate the charge transfer from Fe to hydrogen.

Annapoorni, S.; Rama Rao, K.V.S. (Magnetism and Magnetic Materials Laboratory, Department of Physics, Indian Technology, Madras 600 036, India (IN))

1990-01-01

165

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, Jrme; Larionova, Joulia; Ferreira, Rute A S; Carlos, Luis D; Almeida Paz, Filipe A; Gomes, Jos B R; Trifonov, Alexander; Gurin, Christian; Guari, Yannick

2012-08-01

166

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

167

Magnetic and transport properties of RCr{sub 0.3}Ge{sub 2} (R=Tb, Dy, Ho and Er) compounds  

SciTech Connect

The magnetic and transport properties of ternary rare-earth chromium germanides RCr{sub 0.3}Ge{sub 2} (R=Y and Tb-Er) have been determined. X-ray and neutron diffraction studies indicate that these compounds have the CeNiSi{sub 2}-type structure (space group Cmcm) . Magnetic measurements reveal the antiferromagnetic ordering below T{sub N} equal to 18.5 K (R=Tb), 11.8 K (Dy), 5.8 K (Ho) and 3.4 K (Er). From the neutron diffraction data the magnetic structures have been determined. For TbCr{sub 0.3}Ge{sub 2} and DyCr{sub 0.3}Ge{sub 2} at low temperatures the magnetic ordering can be described by two vectors k{sub 1}=(1/2 ,0,0) and k{sub 2}=(1/4 ,0,1/4), and k{sub 1}'=(1/2 ,0,0) and k{sub 2}'=(1/2 ,0,1/2), respectively. In HoCr{sub 0.3}Ge{sub 2} and ErCr{sub 0.3}Ge{sub 2} the ordering can be described by one propagation vector equal to (1/2 ,1/2 ,0) and (0,0,0.4187(2)), respectively. In DyCr{sub 0.3}Ge{sub 2} some change in the magnetic ordering is observed at T{sub t}=5.1 K. In temperature range from T{sub t} to T{sub N} the magnetic ordering is given by one propagation vector k=(1/2 ,0,0). YCr{sub 0.3}Ge{sub 2} is a Pauli paramagnet down to 1.72 K which suggests that in the entire RCr{sub 0.3}Ge{sub 2} series the Cr atoms do not carry magnetic moments. All compounds studied exhibit metallic character of the electrical conductivity. The temperature dependencies of the lattice parameters reveal strong magnetostriction effect at the respective Neel temperatures. -- Graphical abstract: In the neutron diffraction pattern of TbCr{sub 0.3}Ge{sub 2} compound collected at 1.5 K the additional peaks of magnetic origin form two groups. The first one, with strong intensities, can be indexed by the propagation vector k=(1/2 ,0,0) (a), while the second one, with small intensities, can be described by the propagation vector k=(1/4 ,0,1/4) (b). The analysis of the magnetic peak intensities indicates that the Tb magnetic moments located at the positions Tb1 (0,y,1/4), Tb2 (0,-y,3/4), Tb3 (1/2 ,1/2 +y,1/4) and Tb4 (1/2 ,1/2 -y,3/4) form a collinear structure with the (+ + - -) sequence in the crystallographic unit cell for the first component and (- + + -) for the second. Display Omitted

Gil, A., E-mail: a.gil@ajd.czest.p [Department of Mathematics and Natural Science, J. DLugosz University Czestochowa, Armii Krajowej 13/15, 42-200 Czestochowa (Poland); Kaczorowski, D. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 WrocLaw (Poland); Penc, B. [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland); Hoser, A. [BENSC, Helmholtz-Zentrum Berlin, Glienicker Str. 100, 14-109 Berlin (Germany); SzytuLa, A. [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland)

2011-02-15

168

Structure and magnetic properties of ScFe6Ga6-type RCo5Ga7 (R=Y, Tb, Dy, Ho and Er)  

NASA Astrophysics Data System (ADS)

The structure and magnetic properties of the RCo5Ga7 (R=Y, Tb, Dy, Ho and Er) compounds with the ScFe6Ga6-type structure have been studied. The stability of RCo5Ga7 is closely related with the ratio of the metal radii RRE/R(Co,Ga). With RRE/R(Co,Ga)?1.36, the compounds can be stabilized in the ScFe6Ga6-type structure. The lattice of RCo5Ga7 shrinks as the atomic order of R increases, and it is consistent with the lanthanide contraction. The structure analysis based on X-ray diffraction patterns reveals that in the orthorhombic RCo5Ga7 (Immm), R occupies the 2a site, and Co enters into the 8k and the 4h sites, and Ga is at the 4e, 4f, 4g, 4h and 8k sites. The interatomic distances and the coordination numbers of RCo5Ga7 are provided from the refinement results. The short interatomic distance (less than 2.480 ) between the Co ions results in the negative magnetic interaction, which does not favor ferromagnetic ordering. The magnetic moment of YCo5Ga7 is absent, and RCo5Ga7 (R=Tb, Dy, Ho and Er) may have long-range magnetic ordering with the paramagnetic Curie temperature lower than 5 K.

Chang, Hong; Guo, Yong-Quan; Yang, Lin-Tao; Liu, Quan-Lin; Feng, Wei-Cun; Liang, Jing-Kui; Rao, Guang-Hui

2004-11-01

169

Syntheses, Structure, Magnetism, and Optical Properties of the Partial Ordered Quaternary Interlanthanide Sulfides PrLnYb2S6 (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 reaction of elemental rare earth metals and S using a Sb{sub 2}S{sub 3} flux at 1000 C. These isotypic compounds adopt the F-Ln{sub 2}S3 three-dimensional open channel structure type. Eight-coordinate Pr{sup 3+} ions sit in the channels, which are constructed from three different edge-shared double chains running down the b axis, which contain Yb(1)S{sub 6} octahedra, Yb(2)S{sub 6}, octahedra and LnS{sub 7} monocapped trigonal prisms, respectively. Each double chain connects to four other neighbors by sharing vertices and edges. Considerable disordering in Ln positions was observed in single X-ray diffraction experiments only in the case of Pr/Yb. Least square refinements gave rise to the formulas of Pr{sub 1.34}Yb{sub 2.66}S{sub 6}, of PrTbYb{sub 2}S{sub 6}, and PrDyYb{sub 2}S{sub 6}, which are confirmed by the elemental analysis and magnetic susceptibility measurements. Pr1.34Yb2.66S{sub 6}, PrTbYb{sub 2}S{sub 6} and PrDyYb{sub 2}S{sub 6} are paramagnetic down to 2 K without any indications of long range magnetic ordering. The optical transitions for Pr{sub 1.34}Yb{sub 2.66}S{sub 6}, PrTbYb{sub 2}S{sub 6}, and PrDyYb{sub 2}S{sub 6} are at approximately 1.6 eV. Crystallographic data: Pr{sub 1.34}Yb{sub 2.66}S{sub 6}, monoclinic, space group P2{sub 1}/m, a = 10.960(2), b = 3.9501(8), c = 11.220(2) {angstrom}, {beta} = 108.545(3), V = 460.54(16), Z = 2; PrTbYb{sub 2}S{sub 6}, monoclinic, space group P2{sub 1}/m, a = 10.9496(10), b = 3.9429(4), c = 11.2206(10) {angstrom}, {beta} = 108.525(2), V = 459.33(7), Z = 2; PrDyYb{sub 2}S{sub 6}, monoclinic, space group P2{sub 1}/m, a = 10.9384(10), b = 3.9398(4), c = 11.2037(10) {angstrom}, {beta} = 108.612(2), V = 457.57(7), Z = 2.

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

2008-01-11

170

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

PubMed Central

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

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

2013-01-01

171

Magnetic entropy change and relative cooling power of Gd3Ni6Al2 and Tb3Ni6Al2 compounds  

NASA Astrophysics Data System (ADS)

We present study of the magnetocaloric effects (MCE) in Gd3Ni6Al2 and Tb3Ni6Al2 crystallizing in the Cubic Ce3Ni6Si3-type structure. The two compounds undergo a second-order ferromagnetic transition at Curie temperature TC=105.7 and 57.5 K for Gd3Ni6Al2 and Tb3Ni6Al2, respectively. Magnetization and specific heat are measured as functions of temperature and magnetic field around TC, and the measurements are used to estimate the magnetic entropy change (?Sm) and the relative cooling power (RCP) by both magnetic and calorimetric techniques. A relatively large ?Sm associated with the ferromagnetic transition has been observed over a wide temperature range for both the compounds, leading to a high RCP. The maximum values of ?Sm in a 5 T magnetic field are evaluated to be 6.2 Jkg-1K-1 for Gd3Ni6Al2 and 9.8 Jkg-1K-1 for Tb3Ni6Al2, the corresponding values of RCP are 608 and 461 Jkg-1, respectively. Particularly, both Gd3Ni6Al2 and Tb3Ni6Al2 show higher RCP values even in a small field change that can be generated by a permanent magnet.

Li, D. X.; Nimori, S.; Aoki, D.

2013-03-01

172

Optimization of the synthesis of nanostructured Tb3+-doped Gd2O3 by in-situ luminescence following up.  

PubMed

Nanostructured Tb(3+)-doped Gd(2)O(3) particles have been synthesized from chloride precursors by NaOH addition in a polyol medium. In-situ luminescent spectra have been investigated in order to follow up the process of formation and growth of these particles by varying parameters as the elaboration temperature and the rate of NaOH addition. Contrarily to all the literature related to the "polyol" synthesis, the paper proves that oxide particles can be directly formed at room temperature. These particles are also slightly bigger and organized in nanorods when NaOH is added progressively. Finally, it was found that the influence of further annealing up to 160 degrees C strongly depends on the NaOH addition rate. While preserving the oxide phase, annealing leads to bigger particles only in the case of a progressive addition of NaOH. PMID:19251266

Ou, Meigui; Mutelet, Brice; Martini, Matteo; Bazzi, Rana; Roux, Stphane; Ledoux, Gilles; Tillement, Olivier; Perriat, Pascal

2009-01-31

173

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

SciTech Connect

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

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

2010-09-15

174

The extended chain compounds Ln12(C2)3I17 (Ln=Pr, Nd, Gd, Dy): Synthesis, structure and physical properties  

NASA Astrophysics Data System (ADS)

The title compounds are obtained in high yield from stoichiometric mixtures of Ln, LnI3 and graphite, heated at 900 950 C in welded Ta containers. The crystal structures of new Pr and Nd phases determined by single-crystal X-ray diffraction are related to those of other Ln12(C2)3I17-type compounds (C 2/c, a=19.610(1) and 19.574(4) , b=12.406(2) and 12.393(3) , c=19.062(5) and 19.003(5) , ?=90.45(3) and 90.41(3), for Pr12(C2)3I17 and Nd12(C2)3I17, respectively). All compounds contain infinite zigzag chains of C2-centered metal atom octahedra condensed by edge-sharing into the [tcc]? sequence (c=cis, t=trans) and surrounded by edge-bridging iodine atoms as well as by apical iodine atoms that bridge between chains. The polycrystalline Gd12(C2)3I17 sample exhibits semiconducting thermal behavior which is consistent with an ionic formulation (Ln3+)12(C26 )3(I-)17(e-) under the assumption that one extra electron is localized in metal metal bonding. The magnetization measurements on Nd12(C2)3I17, Gd12(C2)3I17 and Dy12(C2)3I17 indicate the coexistence of competing magnetic interactions leading to spin freezing at Tf=5 K for the Gd phase. The Nd and Dy compounds order antiferromagnetically at TN=25 and 29 K, respectively. For Dy12(C2)3I17, a metamagnetic transition is observed at a critical magnetic field H?25 kOe.

Ryazanov, Mikhail; Mattausch, Hansjrgen; Simon, Arndt

2007-04-01

175

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

176

Calculation of the thermal conductivity of L2SrAl2O7 (L= La, Nd, Sm, Eu, Gd, Dy)  

NASA Astrophysics Data System (ADS)

Density functional perturbation theory, combined with quasi-harmonic approximation theory and the Debye theory, has been used to calculate the thermal conductivity of the double-perovskite perovskite slab-rocksalt layer oxide compounds L2SrAl2O7 (L = La, Nd, Sm, Eu, Gd, and Dy), a promising class of high-temperature thermal insulators. The predicted properties are compared with experimental data and show excellent agreement from room temperature up to 1000 C. This indicates that the methodology is an effective approach to calculating the thermal conductivity of complex, defect-free crystal structures.

Feng, Jing; Wan, Chunlei; Xiao, Bing; Zhou, Rong; Pan, Wei; Clarke, David R.

2011-07-01

177

Mssbauer studies of magnetic behavior of 3d-doped REBa 2 Cu 3? x Fe x O 7+? (RE=Y, Er, Dy, Gd)  

Microsoft Academic Search

A Mssbauer study has been made on57Fe ions substituted into the Cu(1) site of REBa2Cu3?x\\u000a Fe\\u000a x\\u000a O7+? (RE=Y, Er, Dy, Gd;x=0.15, 0.30). At low temperature, the iron atoms antiferromagnetically order with a transition temperature which is dependent\\u000a on the Fe concentration. The temperature dependence of the magnetic subspectra representing Fe ions with various local oxygen\\u000a environments in YBa2Cu3?x\\u000a Fe

C. W. Kimball; B. Dabrowski; Yuehai Liang; Weimin Peng; B. D. Dunlap

1992-01-01

178

Honeycombs of triangles and magnetic frustration in SrL2O4 ( L=Gd , Dy, Ho, Er, Tm, and Yb)  

NASA Astrophysics Data System (ADS)

The crystal structures, magnetic order, and susceptibility have been investigated for magnetically frustrated SrDy2O4 , SrHo2O4 , SrEr2O4 , SrTm2O4 , and SrYb2O4 . Powder neutron-diffraction structural refinements reveal columns of LO6 octahedra that run along one crystallographic direction, with Sr-O polyhedra in the interstices. The lanthanide sublattice displays multiple triangular interconnections: one-dimensional strings form the backbones of four types of chains of lanthanide triangles sharing edges arranged in a honeycomb pattern. This crystal structure produces strong geometric frustration for the magnetic system that is evidenced in both magnetic susceptibility and neutron-scattering data at low temperatures. The susceptibility measurements for the series, including SrGd2O4 for which data are also reported, lack the sharp features characteristic of three-dimensional long-range magnetic ordering. Metamagnetic behavior is observed in the magnetization vs applied field data at 1.8 K for the cases of L=Dy , Er, and Ho. Magnetic neutron-scattering studies for the Dy and Er materials show only very broad magnetic scattering at low temperatures, while the Ho system exhibits long-range two-dimensional order. Any magnetic scattering in the Tm and Yb compounds, if present, was too weak to be detected in these measurements.

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

2005-04-01

179

Preparation of cereal-like Y V O4:Ln3 + (Ln = Sm, Eu, Tb, Dy) for high quantum efficiency photoluminescence  

NASA Astrophysics Data System (ADS)

In this work, preparation of cereal-like architectures Y V O4 and Y V O4:Ln3 + (Ln = Eu, Sm, Dy, Tb) was initiated using a hydrothermal method. During the formation reaction, Na3C6H5O72H2O was used to effectively adjust the concentration of Y3 + species necessary for cereal-like architectures. Phase structure, surface chemistry, morphology, and photoluminescence were characterized by x-ray powder diffraction, Fourier transformed infrared spectra, scanning electron microscopy, transmission electron microscopy, and photoluminescence spectra. All samples crystallize in a tetragonal zircon structure, stably showing a homogeneous cereal-like morphology. This special morphology was constructed by self-assembly of tiny primary particles with a dimension of 31-32 nm. With increasing atomic number of Ln3 + , the lattice dimension of the cereal architectures became monotonously enlarged. This cereal-like architecture is proved unique in significantly improving the quantum efficiencies: the internal quantum efficiencies of 5D0 for Ln = Eu and 4F9/2 for Ln = Dy were 14.6% and 11.4%, respectively, which are all superior over those of the counterparts of nanoparticles reported in the literature. The average lifetime of the 5D0 level for Ln = Eu was calculated to be 98 s, which is longer than that of 50 s of the 4F9/2 level for Ln = Dy. The strong photoluminescence might be the consequence of the effective energy transfer due to the greatly reduced defect centers from this special self-assembly structure.

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

2010-05-01

180

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

181

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

PubMed

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

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

2012-02-09

182

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

183

Fabrication and imaging characterization of high sensitive CsI(Tl) and Gd 2O 2S(Tb) scintillator screens for X-ray imaging detectors  

Microsoft Academic Search

Indirect-detection methods consisted of an X-ray converter and photodiode arrays are more widely used in medical diagnosis and industrial fields. Two major scintillation materials such as terbium-doped gadolinium oxysulfide(Gd2O2S:Tb, Gadox) and thallium-doped cesium iodide(CsI:Tl) are commonly used. In this work, Gadox screens were manufactured by particle in binder (PIB) layer method and CsI:Tl scintillator films with columnar structure were also

Bo Kyung Cha; Jong Yul Kim; Tae Joo Kim; Cheulmuu Sim; Gyuseong Cho

2010-01-01

184

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

Microsoft Academic Search

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

A. del Moral; E. Joven

1990-01-01

185

Magnetism of cyano-bridged Ln3+-M3+ complexes. Part II: one-dimensional complexes (Ln3+ = Eu, Tb, Dy, Ho, Er, Tm; M3+ = Fe or Co) with bpy as blocking ligand.  

PubMed

The reaction of Ln(NO3)3(aq) with K3[Fe(CN)6] or K3[Co(CN)6] and 2,2'-bipyridine in water/ethanol led to 13 one-dimensional complexes: trans-[M(CN)4(mu-CN)2Ln(H2O)4(bpy)]n.4nH2O.1.5nbpy (Ln = Eu3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Lu3+; M = Fe3+, Co3+). The structures for [EuFe]n (1), [TbFe]n (2), [DyFe]n (3), [HoFe]n (4), [ErFe]n (5), [TmFe]n (6), [LuFe]n (7), [EuCo]n (8), [TbCo]n (9), [DyCo]n (10), [HoCo]n (11), [ErCo]n (12), and [TmCo]n (13) have been solved: they crystallize in the triclinic space group P and are isomorphous. They exhibit a supramolecular architecture created by the interplay of coordinative, hydrogen bonding, and pi-pi interactions. A stereochemical study of the eight-vertex polyhedra of the lanthanide ions, based on continuous shape measures, is presented. The Ln3+-Fe3+ interaction is antiferromagnetic in [DyFe]n and [TbFe]n. For [EuFe]n, [HoFe]n, [ErFe]n, and [TmFe]n, there is no sign of any significant interaction. The magnetic behavior of [DyFe]n suggests the onset of weak long-range ferromagnetic ordering at 2.5 K. PMID:16180856

Figuerola, Albert; Ribas, Joan; Casanova, David; Maestro, Miguel; Alvarez, Santiago; Diaz, Carmen

2005-10-01

186

Determination of Some Rare Earth Elements in High Purity Y2O3, Gd2O3 and Dy2O3 by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES).  

National Technical Information Service (NTIS)

A method is described for the determination of four trace rare earth elements in high purity Y/sub 2/O/sub 3/, Gd/sub 2/O/sub 3/ and Dy/sub 2/O/sub 3/ using inductively coupled plasma atomic emission spectrometry (ICP-AES). Due to the complex spectrum of ...

P. Sreerama Murty S. S. Biswas V. R. Nair

1988-01-01

187

X-ray powder diffraction and vibrational spectra studies of rare earth borophosphates Ln{sub 7}O{sub 6}(BO{sub 3})(PO{sub 4}){sub 2} (Ln = La, Nd, Gd, and Dy)  

SciTech Connect

The crystal structure of the isomorphical rare earth borophosphate compounds, Ln{sub 7}O{sub 6}(BO{sub 3})(PO{sub 4}){sub 2} (Ln = La, Nd, Gd and Dy), has been studied by a combination of X-ray powder diffraction (XRD) and vibration spectroscopic techniques. The Raman and infrared spectra of these compounds have been investigated, and their interpretation is discussed on both theoretical and experimental bases. Assignments have been deduced from the systematic investigation of pure compounds and isotopic species. A comparison of vibrational frequencies in La, Na, Gd, and Dy borophosphates reveals that the internal vibrations of the BO{sub 2} and PO{sub 4} ions shift to higher frequency with the decrement of lattice parameters from La to Dy, indicating a strengthening of the phosporus-oxygen and boron-oxygen bonding.

Ying Shi; Hao Zhang; Jinling Yang [Institute of Physics, Beijing (China)] [and others

1997-02-15

188

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

SciTech Connect

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

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

2007-04-15

189

Preparation, crystal structure, magnetic and magnetothermal properties of (Gd{sub x}R{sub 5-x})Si{sub 4}, where R=Pr and Tb, alloys  

SciTech Connect

The series of alloys (Gd{sub x}Tb{sub 5-x})Si{sub 4} (x=0,2.5,3,3.5,4,4.5,5) and (Gd{sub x}Pr{sub 5-x})Si{sub 4} (x=4,4.25,4.5) have been prepared. Their room temperature crystal structure has been established, and dc magnetization and ac magnetic susceptibility have been measured in the temperature range from 4.2 to 550 K and in dc magnetic fields up to 50 kOe. The magnetocaloric effect has been calculated from the magnetization data and, for one of the alloys, from the heat capacity data. The magnetocaloric effect values from the two different measurements are in excellent agreement. The (Gd{sub x}Tb{sub 5-x})Si{sub 4} alloys exhibit magnetocaloric effects in low magnetic fields (<20 kOe) comparable to that of Gd metal and, therefore, they represent a new class of promising magnetic refrigerant materials.

Spichkin, Y. I.; Pecharsky, V. K.; Gschneidner, K. A.

2001-02-01

190

High-temperature transport properties of Ca0.98RE0.02MnO3-? (RE=Sm, Gd, and Dy)  

NASA Astrophysics Data System (ADS)

We report measurements of electrical resistivity and thermopower on CaMnO3-? and Ca0.98RE0.02MnO3-? (RE=Sm, Gd, and Dy) prepared by solid state reaction. CaMnO3-? exhibits nonmetal-like temperature dependence of resistivity while metal-like temperature dependence of thermopower. This inconsistency can be explained by the extrinsic carriers arising from oxygen defects using two-band model. Ca0.98RE0.02MnO3-? exhibits metal-like temperature dependence in both resistivity and thermopower. The transition to metal-like behavior resembles the case in degenerate semiconductors and can be attributed to an impurity band formation with characteristic of hybridized Mn 3d eg and O 2p states due to electron doping via partial substitution of lanthanides for Ca2+ and oxygen defects.

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

2011-05-01

191

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

SciTech Connect

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

Riedemann, T.M.

1996-05-01

192

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 Nel 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

193

Low Energy E1 Transitions between ?[642]5/2 and ?[521]3/2 Bands in ^157Gd and ^159Dy  

NASA Astrophysics Data System (ADS)

In N=93 odd-N rare-earth nuclei, two rotational bands of opposite parity based on ?[521]3/2 and ?[642]5/2 coexist near the yrast line. Since it is well known that even-even nuclei in this region have the K=0^- or 1^- octupole band, this situation gives us a good opportunity to study the low energy E1 transitions in odd-N rare-earth nuclei caused by the octupole collectivity. High spin states of ^157Gd and ^159Dy have been studied by using the multiple Coulomb excitation with Xe beam and the reaction ^150Nd(^13C, 4n) respectively. Rotational bands based on ?[521]3/2 and ?[642]5/2 have been extended to higher spin states in both nuclei. Several E1 transitions between them have been observed and discussed based on the Generalized Intensity Relations. Spin dependences of B(E1) values or B(E1)/B(E2) ratios are compared with those in other odd-A rare-earth nuclei. It is found that the B(E1)/B(E2) ratios for 47/2^- and 43/2^- states in ^159Dy become enhanced relative to those for the lower spin states.

Sugawara, M.; Mitarai, S.; Kusakari, H.; Sugie, M.; Sato, Y.; Oshima, M.; Hayakawa, T.; Toh, Y.; Hatsukawa, Y.; Katakura, J.; Iimura, H.; Zhan, Y. H.

2001-10-01

194

Investigation of the dehydration schemes of NdCl 3-6H 2O, TbQ 36H 2O and DyCl 36H 2O using a fluidized bed  

Microsoft Academic Search

The dehydration schemes of NdCl36H2O, TbCl36H2O and DyQ36H2O were investigated by the fluidized bed technique. Hydrolytic reactions were avoided by using dry mixtures of argon and hydrogen chloride as fluidizing gas. Results were followed up by both chemical and thermal analyses. Non-isothermal as well as isothermal techniques were used. The isothermal technique disclosed the complete dehydration schemes: NdCl36H2O and TbCl36H2O

Johan Sundstrm; Olle Wijk

1997-01-01

195

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

PubMed

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

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

2013-05-22

196

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

SciTech Connect

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

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

2007-11-01

197

Synthesis, characterization, and magnetic properties of new Rh(III) compounds with the KCdCl structure-type: SrMRhO (M = Sm, Eu, Tb, Dy, Ho, Er, and Yb)  

Microsoft Academic Search

The compounds SrMRhO (M = Sm, Eu, Tb, Dy, Ho, Er, and Yb) have been synthesized and structurally characterized by Rietveld refinement of powder X-ray diffraction data in the space group R{bar 3}c; Z = 6. The lattice parameters for the series were found to be a = 9.78570(7) and c = 11.4811(1) , a = 9.7837(1) and c =

R. C. Layland; S. L. Kirkland; H. C. zur Loye

1998-01-01

198

Microstructure and Mssbauer studies on magnetostrictive Tb0.3Dy0.7Fe1.95 - x Nb x ( x = 0, 0.025, 0.05 and 0.075)  

Microsoft Academic Search

Alloys of Dy0.7Tb0.3Fe1.95 - x Nb x ( x = 0, 0.025, 0.05 and 0.075) were prepared in vacuum employing an induction furnace and investigated for the magnetic properties and microstructural features. A significant improvement in the magnetostriction has been obtained for the alloys containing Nb as compared to that of the parent alloy ( x = 0). The Curie

J. Arout Chelvane; Mithun Palit; S. Pandian; M. Manivel Raja; V. Chandrasekaran

2008-01-01

199

Critical behavior of the paramagnetic to antiferromagnetic transition in orthorhombic and hexagonal phases of RMnO3 (R=Sm, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y)  

NASA Astrophysics Data System (ADS)

The critical behavior of the paramagnetic to antiferromagnetic transition in RMnO3 (R = Sm, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y) has been studied with an ac photopyroelectric calorimeter, which gives simultaneously the thermal diffusivity and specific heat as a function of temperature with high resolution around the Nel temperature. RMnO3 (R = Sm, Tb, Dy) has an orthorhombic perovskite structure, whereas the other manganites are hexagonal, thus revealing a strong thermal anisotropy. SmMnO3 with type-A antiferromagnetic ordering exhibits a 3D-XY critical behavior, which could be attributed to the peculiar site anisotropy of Sm3+ and the exchange interaction between Mn3+ and Sm3+ ions. The sinusoidal spin ordering in TbMnO3 and DyMnO3 can be phenomenologically described by the 3D-Heisenberg model. Finally, the hexagonal manganites RMnO3 (R = Ho, Er, Tm, Yb, Lu, Y) are close to the 3D-Heisenberg universality class, ruling out the chiral models predicted by the renormalization group theory.

Oleaga, A.; Salazar, A.; Prabhakaran, D.; Cheng, J.-G.; Zhou, J.-S.

2012-05-01

200

Effect of the crystal structure of small precursor particles on the growth of ?-NaREF4 (RE = Sm, Eu, Gd, Tb) nanocrystals  

NASA Astrophysics Data System (ADS)

The origin of the narrow particle size distributions obtained in the oleic acid-based synthesis of hexagonal phase ?-NaREF4 nanocrystals (RE = Sm, Eu, Gd, Tb) has been investigated. Compared to the standard synthesis, the growth conditions were simplified by using small purified particles of either ?-NaREF4 (cubic phase) or ?-NaREF4 (hexagonal phase) as single-source precursors, thereby avoiding the complications arising from the simultaneous presence of molecular educts and intermediately formed small particles. The study shows that ?-phase as well as ?-phase particles grow by Ostwald-ripening but narrow particle size distributions of the ?-NaREF4 product particles are only obtained when ?-phase precursor particles are employed. Since the small particles are also formed as intermediate products in the standard synthesis of ?-NaSmF4, ?-NaEuF4, ?-NaGdF4 and ?-NaTbF4 particles, their crystal phase is an important parameter to obtain a narrow size distribution in these systems.The origin of the narrow particle size distributions obtained in the oleic acid-based synthesis of hexagonal phase ?-NaREF4 nanocrystals (RE = Sm, Eu, Gd, Tb) has been investigated. Compared to the standard synthesis, the growth conditions were simplified by using small purified particles of either ?-NaREF4 (cubic phase) or ?-NaREF4 (hexagonal phase) as single-source precursors, thereby avoiding the complications arising from the simultaneous presence of molecular educts and intermediately formed small particles. The study shows that ?-phase as well as ?-phase particles grow by Ostwald-ripening but narrow particle size distributions of the ?-NaREF4 product particles are only obtained when ?-phase precursor particles are employed. Since the small particles are also formed as intermediate products in the standard synthesis of ?-NaSmF4, ?-NaEuF4, ?-NaGdF4 and ?-NaTbF4 particles, their crystal phase is an important parameter to obtain a narrow size distribution in these systems. Electronic supplementary information (ESI) available: XRD patterns of the samples, particle size histograms from TEM and DLS measurements, Rietveld fits, emission spectra of NaGdF4:Eu particles with different Eu3+ concentrations and weighted amounts of NaREF4 precursor particles for the synthesis of the final products. See DOI: 10.1039/c2nr33083k

Vo, Benjamin; Nordmann, Jrg; Uhl, Andreas; Komban, Rajesh; Haase, Markus

2012-12-01

201

Growth and optical properties of nanocrystalline Gd3Ga5O12:Ln (Ln=Eu,Tb,Er) powders and thin films via Pechini sol gel process  

NASA Astrophysics Data System (ADS)

Rare earth (Eu3+, Tb3+, Er3+)-doped gadolinium gallium garnet (Gd3Ga5O12, GGG) nanocrystalline powder and thin film phosphors were prepared by the Pechini sol gel process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM) as well as photoluminescence (PL) spectra were used to characterize the resulting powder and film samples. Both the powders and the coatings crystallized completely at 800 C. The dopant rare earth ions show their characteristic emissions in Gd3Ga5O12 phosphors, i.e., 5D0 7FJ(J=1,2,3,4) transitions for Eu3+, 5D4 7FJ(J=3,4,5,6) transitions for Tb3+ and (2H11/2 4I15/2, 4S3/2 4I15/2) transitions for Er3+, respectively. In addition, the near infrared emission spectra (NIR) and the near infrared to visible upconversion (anti-Stokes) luminescence of Er3+ were also observed in the Er3+-doped Gd3Ga5O12 samples. Possible mechanism responsible for the upconversion luminescence of Er3+ was proposed.

Pang, Maolin; Lin, Jun

2005-10-01

202

Zero field damping capacity in (Tb{sub {ital x}}Dy{sub 1{minus}{ital x}})Fe{sub {ital y}}  

SciTech Connect

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{endash}dysprosium{endash}iron compounds by quasistatic stress{endash}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 ({Delta}{ital W}/{ital W}) was calculated from the stress{endash}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 {ital Q}{sup {minus}1}=0.28. The damping is almost independent of stress in a multi-phase sample, (Tb{sub 0.6}Dy{sub 0.4})Fe{sub 1.4}, which contains both Laves phase and elemental rare earth. {copyright} {ital 1996 American Institute of Physics.}

Teter, J.P.; Hathaway, K.B. [Naval Surface Warfare Center, Silver Spring, Maryland 20903-5640 (United States); Clark, A.E. [Clark Associates, Adelphi, Maryland 20783 (United States)

1996-04-01

203

59Co NMR study of NdCo2, GdCo2, TbCo2 and HoCo2  

NASA Astrophysics Data System (ADS)

We have observed the 59Co spectra of the Laves phase Co compounds with Nd, Gd, Tb and Ho. We observe a spectrum consisting of a pair of lines for Nd, Tb and Ho compounds, because the Co sites are magnetically inequivalent in the presence of dipolar or pseudodipolar fields. For the heavy rare earth compounds, the magnitude of this splitting is comparable to the dipolar splitting produced by the neighboring spins, but for Nd it is much larger. The Nd compound is also anomalous in that the average hyperfine field is only 37.2 kOe while for the 3 heavy rare earth compounds it is about 60 kOe. The magnitude of the hyperfine field is discussed in terms of a simple model relating it to the cobalt moment and the rare earth spin.

Rubinstein, M.; Lubitz, P.; Koon, N. C.

1981-10-01

204

X-Ray Powder Diffraction and Vibrational Spectra Studies of Rare Earth Borophosphates, Ln 7O 6(BO 3)(PO 4) 2( Ln=La, Nd, Gd, and Dy)  

Microsoft Academic Search

The crystal structure of the isomorphical rare earth borophosphate compounds,Ln7O6(BO3)(PO4)2(Ln=La, Nd, Gd and Dy), has been studied by a combination of X-ray powder diffraction (XRD) and vibration spectroscopic techniques. The Raman and infrared spectra of these compounds have been investigated, and their interpretation is discussed on both theoretical and experimental bases. Assignments have been deduced from the systematic investigation of

Ying Shi; Jingkui Liang; Hao Zhang; Jinling Yang; Weidong Zhuang; Guanghui Rao

1997-01-01

205

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

206

Effect of the crystal structure of small precursor particles on the growth of ?-NaREF4 (RE = Sm, Eu, Gd, Tb) nanocrystals.  

PubMed

The origin of the narrow particle size distributions obtained in the oleic acid-based synthesis of hexagonal phase ?-NaREF(4) nanocrystals (RE = Sm, Eu, Gd, Tb) has been investigated. Compared to the standard synthesis, the growth conditions were simplified by using small purified particles of either ?-NaREF(4) (cubic phase) or ?-NaREF(4) (hexagonal phase) as single-source precursors, thereby avoiding the complications arising from the simultaneous presence of molecular educts and intermediately formed small particles. The study shows that ?-phase as well as ?-phase particles grow by Ostwald-ripening but narrow particle size distributions of the ?-NaREF(4) product particles are only obtained when ?-phase precursor particles are employed. Since the small particles are also formed as intermediate products in the standard synthesis of ?-NaSmF(4), ?-NaEuF(4), ?-NaGdF(4) and ?-NaTbF(4) particles, their crystal phase is an important parameter to obtain a narrow size distribution in these systems. PMID:23235555

Vo, Benjamin; Nordmann, Jrg; Uhl, Andreas; Komban, Rajesh; Haase, Markus

2012-12-13

207

Magnetic, magnetocaloric and magnetotransport properties of RSn1+xGe1?x compounds (R=Gd, Tb, and Er; x=0.1)  

NASA Astrophysics Data System (ADS)

We have studied the magnetic, magnetocaloric and magnetotransport properties of RSn1+xGe1?x(R=Gd, Tb, and Er; x=0.1) series by means of magnetization, heat capacity and resistivity measurements. It has been found that all the compounds crystallize in the orthorhombic crystal structure described by the centrosymmetric space group Cmcm (No. 63). The magnetic susceptibility and heat capacity data suggest that all the compounds are antiferromagnetic. Large negative values of ?p in case of GdSn1.1Ge0.9 and TbSn1.1Ge0.9 indicate that strong antiferromagnetic interactions are involved, which is also reflected in the magnetization isotherms. On the other hand ErSn1.1Ge0.9 shows weak antiferromagnetic interaction. The heat capacity data have been analyzed by fitting the temperature dependence and the values of ?D and ? have been estimated. Among these three compounds, ErSn1.1Ge0.9 shows considerable magnetic entropy change of 9.5 J/kg K and an adiabatic temperature change of 3.2 K for a field of 50 kOe. The resistivity data in different temperature regimes have been analyzed and the dominant contributions have been identified. All the compounds show small but positive magnetoresistance.

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

2013-09-01

208

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

209

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

210

Microstructure and Mssbauer studies on magnetostrictive Tb 0.3 Dy 0.7 Fe 1.95??? x Nb x ( x = 0, 0.025, 0.05 and 0.075)  

Microsoft Academic Search

Alloys of Dy0.7Tb0.3Fe1.95???x\\u000a Nb\\u000a x\\u000a (x = 0, 0.025, 0.05 and 0.075) were prepared in vacuum employing an induction furnace and investigated for the magnetic properties\\u000a and microstructural features. A significant improvement in the magnetostriction has been obtained for the alloys containing\\u000a Nb as compared to that of the parent alloy (x = 0). The Curie temperature and the Fe

J. Arout Chelvane; Mithun Palit; S. Pandian; M. Manivel Raja; V. Chandrasekaran

211

Color tunable emission in Ce(3+) and Tb(3+) co-doped Ba2Ln(BO3)2Cl (Ln=Gd and Y) phosphors for white light-emitting diodes.  

PubMed

Ce(3+) and Tb(3+) co-doped Ba2Ln(BO3)2Cl (Ln=Y and Gd) green emitting phosphors were prepared by solid state reaction in reductive atmosphere. The emission and excitation spectra as well as luminescence decays were investigated, showing the occurrence of efficient energy transfer from Ce(3+) to Tb(3+) in this system. The phosphors exhibit both a blue emission from Ce(3+) and a green emission from Tb(3+) under near ultraviolet light excitation with 325-375nm wavelength. Emission colors of phosphors could be tuned from deep blue through cyan to green by adjusting the Tb(3+) concentrations. The energy transfer efficiency and emission intensity of Ba2Y(BO3)2Cl:Ce(3+), Tb(3+) precede those of Ba2Gd(BO3)2Cl:Ce(3+), Tb(3+), and the sample Ba2Y(BO3)2Cl:0.03Ce(3+), 0.10Tb(3+) is the best candidate for n-UV LEDs. PMID:23973604

Zhang, Niumiao; Guo, Chongfeng; Jing, Heng; Jeong, Jung Hyun

2013-08-03

212

Structural trends from a consistent set of single-crystal data of RFeAsO ( R=La , Ce, Pr, Nd, Sm, Gd, and Tb)  

NASA Astrophysics Data System (ADS)

A crystal-growth technique for single crystals of RFeAsO ( R=La , Ce, Pr, Nd, Sm, Gd, and Tb) using NaI/KI as flux is presented. Crystals with a size up to 300?m were isolated for single-crystal x-ray diffraction measurements. Lattice parameters were determined by LeBail fits of x-ray powder data against LaB6 standard. A consistent set of structural data is obtained and interpreted in a hard-sphere model. Effective radii for the rare-earth metal atoms in RFeAsO are deduced. The relation of the intraplane and interplane distances of the arsenic atoms is identified as limiter of the phase formation, and its influence on Tc is discussed.

Nitsche, F.; Jesche, A.; Hieckmann, E.; Doert, Th.; Ruck, M.

2010-10-01

213

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

NASA Astrophysics Data System (ADS)

The electronic structure of the ternary rare-earth chromium antimonides RECrSb3 (RE=La-Nd, Sm, Gd-Dy, Yb) has been examined by high-resolution X-ray photoelectron spectroscopy (XPS) for the first time. The RE 3d or 4d core-line spectra are substantially complicated by the presence of satellite peaks but their general resemblance to those of RE2O3 tends to support the presence of trivalent RE atoms in RECrSb3. However, the Yb 4d spectrum of YbCrSb3 also shows peaks that are characteristic of divalent ytterbium. The Cr 2p core-line spectra exhibit asymmetric lineshapes and little change in binding energy (BE) relative to Cr metal, providing strong evidence for electronic delocalization. The Sb 3d core-line spectra reveal slightly negative BE shifts relative to elemental antimony, supporting the presence of anionic Sb species in RECrSb3. The experimental valence band spectrum of LaCrSb3 matches well with the calculated density of states, and it can be fitted to component peaks belonging to individual atoms to yield an average formulation that agrees well with expectations (La3+Cr3+(Sb2-)3). On progressing from LaCrSb3 to NdCrSb3, the 4f-band in the valence band spectra grows in intensity and shifts to higher BE. The valence band spectrum for YbCrSb3 also supports the presence of divalent ytterbium.

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

2012-12-01

214

Oxide-ion conduction and dielectric relaxation in the fluorite-type Zr0.8Ln0.2O1.9 (Ln = Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu) system  

NASA Astrophysics Data System (ADS)

The electrical conductivity and dielectric properties of the Zr0.8Ln0.2O1.9 (Ln = Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu) system which have a cubic fluorite-type structure were investigated in order to clarify a dynamic property of oxygen vacancy in oxide-ion conductors. The frequency dependences of dielectric constants (epsilonr') were successfully explained by the superposition of Debye-type polarizations and electrolyte-electrode interfacial polarizations. The ac conductivity (?ac) agreed with the calculated values using the dielectric parameters. It was found that the compositional dependence of dielectric properties was similar to that of ?ac.

Kawamoto, Jun-ichi; Yagi, Yuhji; Saito, Miwa; Yamamura, Hiroshi

2011-06-01

215

Ferromagnetic resonance in GdAl2 crystals doped with anisotropic rare-earth ions  

Microsoft Academic Search

Ferromagnetic resonance measurements of the magnetic anisotropy and resonance linewidth are reported for single-crystal specimens of the cubic Laves-phase intermetallic compound GdAl2 and for RxGd1-xAl2 where R is a heavy rare-earth ion. The doping levels of the samples were: for R=Tb, x=0.0025, 0.01, 0.02, 0.05; for R=Dy, x=0.02; for R=Ho, x=0.02; for R=Er, x=0.01, 0.03. Microwave frequencies close to 9.3,

F. Pelegrini; R. W. Teale; S. Abell; D. St. P. Bunbury

1984-01-01

216

Synthesis and structure of a new family of 3d-4f heterometallic compounds Rb7LnFe6O2(PO4)8 (Ln=Sm, Eu, Gd, Dy): Magnetic properties of the Sm-, Gd-, Dy-derivatives  

NASA Astrophysics Data System (ADS)

A new family of mixed lanthanide(III) and iron(III) oxo-phosphate phases, Rb7LnFe6O2(PO4)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 LnO6 octahedral, FeO5 trigonal bipyramidal (tbp), and ?3-oxo [Fe4O18] tetrameric units interconnected through PO4 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 TN=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.

Sanjeewa, Liurukara D.; Palmer West, J.; Hwu, Shiou-Jyh

2012-08-01

217

Studies of Heat-induced Agglomeration in Tb-doped Gd_2O3 Quantum Dots Using X-ray Excited Luminescence, X-ray Diffraction, and Transmission Electron Microscopy  

Microsoft Academic Search

X-ray excited luminescence (XEL) and x-ray diffraction (XRD) techniques have been employed to study the crystal structure and x-ray-to-visible down-conversion efficiency in green-light-emitting Gd_2O_3:Tb quantum dots prepared by a microemulsion method followed by heat treatment at different temperatures. As the quantum dots are heated from room temperature to 1000^oC, XRD data exhibit a three-step transition from amorphous to crystalline Gd_2O_3.

Y. L. Soo; S. Huang; G. Kioseoglou; S. Kim; Y. H. Kao; Y. W. Yang; L. J. Lai; V. Chhabra; B. Kulkarni; J. V. D. Veliadis; R. N. Bhargava

2000-01-01

218

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

219

Inorganic-salt-induced morphological transformation and luminescent performance of GdF3 nanostructures.  

PubMed

Inorganic-salt-induced morphological evolution of GdF3 crystals was demonstrated for the first time in a mild hydrothermal process. By varying the amount of inorganic salt, the GdF3 crystals could transform from uniform elliptic nanostructures to submicroplates. The increase of ionic strength, hindered diffusion of reactant ions, and selectively adsorption of barium cations were responsible for such morphological transformation. Besides, relatively low concentration of F(-) contributed to the formation of GdF3 in the presence of foreign inorganic salt, instead of ternary fluoride. In addition, the luminescence properties of the as-formed nanostructures were investigated by singly doping Eu(3+), Tb(3+), and Dy(3+) into the GdF3 matrix. PMID:23503764

Zhao, Qi; L, Wei; Guo, Ning; Jia, Yongchao; Lv, Wenzhen; Shao, Baiqi; Jiao, Mengmeng; You, Hongpeng

2013-05-21

220

Origin of superconducting carriers in ``non-doped'' T'-(La,RE)2CuO4 (RE = Sm, Eu, Gd, Tb, Lu, and Y) prepared by molecular beam epitaxy  

Microsoft Academic Search

We have performed a systematic investigation of the variations of the lattice constants with substituent rare-earth element concentration x in the nominally undoped superconductors T-La2-x3+REx3+CuO4 (RE = Sm, Eu, Gd, Tb, Lu, and Y), which we have recently discovered using MBE. The results show both the in-plane and out-of-plane lattice constants (a0 and c0 linearly decrease with x, whose extrapolation

M. Noda; A. Tsukada; H. Yamamoto; M. Naito

2005-01-01

221

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

SciTech Connect

The lanthanide coinage-metal diarsenides LnTAs{sub 2} (Ln=La, Ce-Nd, Sm; T=Ag, Au) have been reinvestigated and their structures have been refined from single crystal X-ray data. Two different distortion variants of the HfCuSi{sub 2} type are found: PrAgAs{sub 2}, NdAgAs{sub 2}, SmAgAs{sub 2}, GdAgAs{sub 2}, TbAgAs{sub 2}, NdAuAs{sub 2} and SmAuAs{sub 2} crystallize as twofold superstructures in space group Pmcn with the As atoms of their planar layers forming zigzag chains, whereas LaAgAs{sub 2}, CeAgAs{sub 2} and PrAuAs{sub 2} adopt a fourfold superstructure (space group Pmca) with cis-trans chains of As atoms. The respective atomic positions can be derived from the HfCuSi{sub 2} type by group-subgroup relations. The compounds with zigzag chains of As atoms exhibit metallic behaviour while those with cis-trans chains are semiconducting as measured on powder pellets. The majority of the compounds including 4f elements show antiferromagnetic ordering at T{sub N}<20 K. - Text3: Zigzig vs. cis-trans.

Rutzinger, D.; Bartsch, C. [Anorganische Chemie, Fachrichtung Chemie und Lebensmittelchemie, Technische Universitaet Dresden, D-01062 Dresden (Germany); Doerr, M. [Institut fuer Festkoerperphysik, Technische Universitaet Dresden, D-01062 Dresden (Germany); Rosner, H. [Max-Planck-Institut fuer Chemische Physik fester Stoffe, Noethnitzer Str. 40, D-01187 Dresden (Germany); Neu, V. [IFW Dresden, Institut fuer metallische Werkstoffe, Helmholtzstr. 20, D-01069 Dresden (Germany); Doert, Th., E-mail: thomas.doert@chemie.tu-dresden.d [Anorganische Chemie, Fachrichtung Chemie und Lebensmittelchemie, Technische Universitaet Dresden, D-01062 Dresden (Germany); Ruck, M. [Anorganische Chemie, Fachrichtung Chemie und Lebensmittelchemie, Technische Universitaet Dresden, D-01062 Dresden (Germany)

2010-03-15

222

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

223

Electron correlation and the metal-insulator transition of the pyrochlore molybdates R2Mo2O7 (R=Nd,Sm,Gd,Tb,Y)  

NASA Astrophysics Data System (ADS)

The bulk and surface electronic structures of pyrochlore-type molybdenum oxides R2Mo2O7 ( R=Nd , Sm, Gd, Tb, and Y) have been studied by using photoelectron spectroscopy (PES) at high and low excitation energies. The spectra measured at different excitation energies were distinctly different in shape. PES spectra were found to depend on R . In particular, the high-resolution low-energy PES spectra near the Fermi level (EF) showed a noticeable change of the spectral intensity in accordance with the metal-insulator (M-I) transition as a function of R . We have deconvoluted the true bulk and surface spectra and demonstrated that the above-mentioned near- EF feature reflects the bulk electronic states. Furthermore, we propose that the M-I transition can be understood as a Mott transition induced by the R dependence of U/t , the ratio between the Coulomb repulsion energy, and the hopping term through a comparison between the experimentally derived bulk electronic states and band-structure calculation.

Higashiya, A.; Imada, S.; Yamasaki, A.; Irizawa, A.; Sekiyama, A.; Suga, S.; Taguchi, Y.; Iwama, M.; Ohgushi, K.; Tokura, Y.

2007-04-01

224

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

PubMed

The synthesis and characterization of a family of heterometallic Ni4Ln2 complexes (Ln = Pr(1), Sm(2), Eu(3), Gd(4), Tb(5), Ho(6) and Er(7)) of the formula [Ni2LnL1L2(OH)(H2O)]2 are reported, where H4L1 is 3,3?-(1E,1?E)-(2,2?-(2-aminoethylazanediyl)bis(ethane-2,1-diyl)bis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)bis(2-hydroxybenzoic acid) and H2L2 is 3-formyl-2-hydroxybenzoic acid. The molecular structures of 17 were determined by single-crystal X-ray diffraction and reveal that they are isostructural. In all of these compounds, the six metal ions are held together to form a novel Ni4Ln2O10 core and exhibit a relatively rare dumbbell-type structure. In these compounds, the Ni ions are in slightly distorted square-pyramidal or octahedral environments. An all-oxygen coordination environment (8O) is present around the central lanthanide ion, which is present in a distorted square antiprismatic geometry. The LnLn and LnOavg bond distances in 17 show a gradual reduction proceeding from 1 to 7, in accordance with the lanthanide contraction. The luminescent properties of all the compounds have been studied. The magnetic susceptibility analysis demonstrate antiferromagnetic interactions within complex 4. PMID:23396382

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

2013-04-14

225

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

SciTech Connect

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

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

1991-03-01

226

Low temperature preparation and characterization of In1-xLnxBO3 (x=0.0 and 0.05; Ln=Gd, Eu, Dy and Sm): ESR of In0.95Gd0.05BO3 and emission of In0.95Eu0.05BO3.  

PubMed

Indium borate and rare earth substituted indium borates (In(1-x)Ln(x)BO(3) (x=0.0 and 0.05; Ln=Gd, Eu, Dy and Sm)) are prepared at low temperature by metathesis reaction using InCl(3), LnCl(3) and NaBO(2). They are characterized by powder XRD and infrared spectroscopy. All the compositions (In(1-x)Ln(x)BO(3)) crystallize in hexagonal lattice with calcite structure. These borates gave characteristic IR vibrations of planar BO(3) group. Spin-Hamiltonian parameters for Gd(3+) are deduced from room temperature electron spin resonance spectrum of In(0.95)Gd(0.05)BO(3). The electron spin resonance spectrum of In(0.95)Gd(0.05)BO(3) gave several anisotropic lines with g>2.0. The ESR spectrum of the sample belongs to the "intermediate" category with 1/4

Velchuri, Radha; Vijaya Kumar, B; Rama Devi, V; Ravi Kumar, K; Prasad, G; Vithal, M

2009-08-08

227

Low temperature preparation and characterization of In 1- xLn xBO 3 ( x = 0.0 and 0.05; Ln = Gd, Eu, Dy and Sm): ESR of In 0.95Gd 0.05BO 3 and emission of In 0.95Eu 0.05BO 3  

NASA Astrophysics Data System (ADS)

Indium borate and rare earth substituted indium borates (In 1- xLn xBO 3 ( x = 0.0 and 0.05; Ln = Gd, Eu, Dy and Sm)) are prepared at low temperature by metathesis reaction using InCl 3, LnCl 3 and NaBO 2. They are characterized by powder XRD and infrared spectroscopy. All the compositions (In 1- xLn xBO 3) crystallize in hexagonal lattice with calcite structure. These borates gave characteristic IR vibrations of planar BO 3 group. Spin-Hamiltonian parameters for Gd 3+ are deduced from room temperature electron spin resonance spectrum of In 0.95Gd 0.05BO 3. The electron spin resonance spectrum of In 0.95Gd 0.05BO 3 gave several anisotropic lines with g > 2.0. The ESR spectrum of the sample belongs to the "intermediate" category with 1/4 < HCF/ h? < 1. The local symmetry of Eu 3+ in In 0.95Eu 0.05BO 3 is obtained from its emission spectrum. The R/O ratio of In 0.95Eu 0.05BO 3 suggests the occupation of In 3+ site by Eu 3+ with near symmetric octahedral geometry.

Velchuri, Radha; Vijaya Kumar, B.; Rama Devi, V.; Ravi Kumar, K.; Prasad, G.; Vithal, M.

2009-10-01

228

Size dependent magnetic moments and electric polarizabilities of free Tb, Ho, and Tm clusters  

NASA Astrophysics Data System (ADS)

Stern-Gerlach deflection measurements have been performed on rare earth clusters TbN, HoN, and TmN (N<=40) at cryogenic temperatures (T<=77 K). TbN and HoN share a common size dependence in their magnetic moments. They both exhibit common ``magic number'' sizes which show reduced net magnetic moments, similar to previous observations for Gd and Dy clusters. TmN have smaller magnetic moments that do not differ significantly between cluster sizes. The reduced net magnetic moments are evidence that the atomic moments are canceled by a canted or antiferromagnetic alignment. Electric deflection experiments reveal that TmN have electric dipole moments and show an enhanced response to an electric field compared to TbN and HoN.

Bowlan, J.; van Dijk, C. N.; Kirilyuk, A.; Liang, A.; Yin, S.; Rasing, Th.; de Heer, W. A.

2010-05-01

229

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

230

Tilted Uniaxial Magnetic Anisotropy in Sputtered TbFeCo Films  

NASA Astrophysics Data System (ADS)

Tb x(Fe50Co50)1- x films were deposited on glass slides using a DC sputtering apparatus. Torque measurements revealed that both perpendicular and in-plane uniaxial anisotropy components are induced in resputtered films with FeCo-dominant composition. The easy axis of the in-plane anisotropy component is aligned with the magnetic field applied during deposition. Torque curve analysis revealed that tilting of the easy axis from the film normal in alternate directions can reproduce the measured torque curves very well. In GdCo, DyCo and ErCo films, however, no appreciable in-plane uniaxial anisotropy was induced.

Shiomi, Shigeru; Kato, Junji; Saito, Seiji; Kobayashi, Tadashi; Masuda, Morio

1994-08-01

231

Magnetic characteristics of rare-earth indium RIn (R=Y, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm) intermetallic compounds  

Microsoft Academic Search

Measurements of the magnetic susceptibility of the RIn compounds from 4.2 to 270 K have been made. All compounds except YIn and SmIn exhibit Curie-Weiss behavior at high temperatures with effective magnetic moments agreeing reasonably well with the free-ion 3+ picture modified by RKKY exchange except for GdIn, which gives an unusually high value for the effective moment. With the

H. Gamari-Seale; T. Anagnostopoulos; J. K. Yakinthos

1979-01-01

232

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 solgel 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 1200C. 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

233

UV-visible Faraday rotators based on rare-earth fluoride single crystals: LiREF4 (RE = Tb, Dy, Ho, Er and Yb), PrF3 and CeF3.  

PubMed

High optical quality LiREF(4) (RE = Tb(3+), Dy(3+), Ho(3+), Er(3+) and Yb(3+)), PrF(3) and CeF(3) single crystals have been grown by the Czochralski technique. Their magneto-optical properties have been measured and analyzed in detail in the ultraviolet-visible wavelength region, and their figures of merit as Faraday rotators have been determined. CeF(3) presents superior properties above 300 nm, showing a figure of merit higher than that of the reference material, terbium-gallium-garnet, which is nowadays used in the visible-near infrared. PrF(3) is the best rotator for the 220-300 nm range. Towards shorter wavelength and in the vacuum ultraviolet, it is shown that the LiREF(4) crystals are unique rotators. Overall, the rare-earth fluoride single crystals studied here exhibit better properties than other materials considered so far, and therefore they have potential to cover the increasing demand for new and improved Faraday rotators in the ultraviolet-visible wavelength region. PMID:22714507

Vasyliev, Valentyn; Villora, Encarnacon G; Nakamura, Masaru; Sugahara, Yoshiyuki; Shimamura, Kiyoshi

2012-06-18

234

Magnetic alignment in 2212 Bi-based superconducting system: I. Magnetic orientation of BiSrCa{sub 1-{ital x}}(RE){sub {ital x}}CuO{sub 8-{ital y}} [(RE)=Gd, Dy, Ho, Er] powder dispersed in epoxy resin at room temperature  

Microsoft Academic Search

The magnetic anisotropy of rare-earth substituted 2212 materials (BiSrCa{sub 0.8}RE{sub 0.2}CuO{sub {ital x}} with RE=Gd, Dy, Ho, Er) is put into evidence. Superconducting powder dispersed in epoxy resin is oriented under an external magnetic field (4T) in a direction which depends on the nature of the rare-earth used in the substitution. Both directions of observation (parallel or perpendicular to the

S. Stassen; R. Cloots; P. Vanderbemden; P. A. Godelaine; H. Bougrine; A. Rulmont; M. Ausloos

1996-01-01

235

Measurement of the K shell X-ray production cross-sections and fluorescence yields for Nd, Eu, Gd, Dy and Ho using radioisotope X-ray fluorescence in the external magnetic field  

NASA Astrophysics Data System (ADS)

The effect of external magnetic field on the K? and K? X-ray production cross-sections and K shell fluorescence yields for ferromagnetic elements Nd, Gd and Dy and paramagnetic elements Eu and Ho have been measured at the excitation energy of 59.5 keV ? -rays from 241Am radioactive source of strength 100 mCi in the external magnetic field of intensities 0.75 T. Furthermore, IK? /IK? intensity ratios for these elements have been measured in the external magnetic field. The K X-rays from different targets were detected using a high resolution Si(Li) semiconductor detector. For B = 0, the measured K X-ray production cross-sections, K shell fluorescence yields and the IK? /IK? intensity ratios were compared with the experimental and theoretical data in literature. The results have shown that the fluorescence parameters as photoionization cross section, fluorescence yield, radiation rates and spectral linewidth can change when the irradiation is conducted in a magnetic field.

Demir, D.; ?ahin, Y.

2007-05-01

236

Effects of rare-earth elements on the glass-forming ability and mechanical properties of Cu 46 Zr 47? x Al 7 M x (M = Ce, Pr, Tb, and Gd) bulk metallic glasses  

Microsoft Academic Search

Cu46Zr47?x\\u000a Al7M\\u000a x\\u000a (M = Ce, Pr, Tb, and Gd) bulk metallic glassy (BMG) alloys were prepared by copper-mold vacuum suction casting. The effects\\u000a of rare-earth elements on the glass-forming ability (GFA), thermal stability, and mechanical properties of Cu46Zr47?x\\u000a Al7M\\u000a x\\u000a were investigated. The GFA of Cu46Zr47?x\\u000a Al7M\\u000a x\\u000a (M = Ce, Pr) alloys is dependent on the content of

Zhiwei Xie; Yongzhang Zhang; Yuanzheng Yang; Xianzhao Chen; Pingjun Tao

2010-01-01

237

Laser photoionization spectroscopy of rare-earth elements: New results on nuclear electromagnetic moments and charge radii of Eu, Gd and Tb isotopes  

Microsoft Academic Search

New results on spins, electromagnetic moments and isotopic changes of nuclear charge radii for{63\\/157 159}Eu,{64\\/146, 148, 150}Cd and{65\\/147 155, 157, 159}Tb have been obtained from hyperfine structure and isotope shifte measured with laser resonance photoionization technique. These results complement two-dimensional picture (with respect to H and Z) of the changes of nuclear ground state properties near the ``critical'' neutron numbers

G. D. Alkhazov; A. E. Barzakh; V. P. Denisov; V. S. Ivanov; I. Y. Chubukov; V. N. Fedoseev; V. S. Letokhov; V. I. Mishin; S. K. Sekatsky

1990-01-01

238

Synthesis and crystal structure of metal-organic frameworks [Ln2(pydc-3,5)3(H2O)9]n3nH2O (Ln = Sm, Eu, Gd, Dy; pydc-3,5 = pyridine-3,5-dicarboxylate) along with the photoluminescent property of its europium one  

NASA Astrophysics Data System (ADS)

Rare-earth metal-organic frameworks, [Ln2(pydc)3(H2O)9]n3nH2O (Ln = Sm, Eu, Gd, Dy; pydc = pyridine-3,5-dicarboxylate), were synthesized and characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction. The solid-state photoluminescence measurements exhibited red light-emitting characteristic of europium (III) coordination polymer. The title compounds consist of one-dimensional dual chains, in which each metal atom is nine-coordinated with oxygen atoms.

Shi, Qisong; Zhang, Shu; Wang, Qian; Ma, Hongwei; Yang, Guoqiang; Sun, Wen-Hua

2007-06-01

239

Laser photoionization spectroscopy of rare-earth elements: New results on nuclear electromagnetic moments and charge radii of Eu, Gd and Tb isotopes  

Microsoft Academic Search

New results on spins, electromagnetic moments and isotopic changes of nuclear charge radii for\\u000a 63\\u000a 157159\\u000a Eu,\\u000a 64\\u000a 146, 148, 150\\u000a Cd and\\u000a 65\\u000a 147155, 157, 159\\u000a Tb have been obtained from hyperfine structure and isotope shifte measured with laser resonance photoionization technique.\\u000a These results complement two-dimensional picture (with respect to H and Z) of the changes of nuclear ground

G. D. Alkhazov; A. E. Barzakh; V. P. Denisov; V. S. Ivanov; I. Y. Chubukov; V. N. Fedoseev; V. S. Letokhov; V. I. Mishin; S. K. Sekatsky

1990-01-01

240

119Sn Mssbauer 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 Mssbauer 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

241

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

242

Level structure of 146Tb  

NASA Astrophysics Data System (ADS)

The level structure of the doubly odd nucleus 146Tb has been studied via the 118Sn(32S, 1p3n) reaction using techniques of in-beam ? -ray spectroscopy. Measurements of ? -ray anisotropies, X-? and ? -? -t coincidences were performed with 12 BGO(AC)HPGe detectors. Based on the measured results, the level scheme of 146Tb has been revised significantly and extended up to an excitation energy of 8.39 MeV. The level structure has been interpreted qualitatively by coupling an h 11/2 proton-particle and an h 11/2 neutron-hole to the excited states in the 146Gd core.

Xie, C. Y.; Zhou, X. H.; Zheng, Y.; Zhang, Y. H.; Liu, Z.; Gan, Z. G.; Hayakawa, T.; Oshima, M.; Toh, T.; Shizuma, T.; Katakura, J.; Hatsukawa, Y.; Matsuda, M.; Kusakari, H.; Sugawara, M.; Furuno, K.; Komatsubara, T.

2004-01-01

243

Tuberculosis (TB): Treatment  

MedlinePLUS

Tuberculosis Diagnosing Tuberculosis Treating Tuberculosis TB Preventive Treatment Latent TB Infection Active TB Disease Drug-Resistant Tuberculosis ... to cooperate fully in the therapy program. Both latent TB infection and active TB disease are treated ...

244

Tuberculosis (TB)  

MedlinePLUS

... email. Register for ENews Home > Lung Disease > Tuberculosis Tuberculosis Tuberculosis (TB) is an infectious disease that usually infects ... can attack almost any part of the body. Tuberculosis is spread from person to person through the ...

245

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

SciTech Connect

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

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

2007-05-15

246

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

SciTech Connect

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

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

2010-05-15

247

The peculiar magnetic property evolution along RCu3Mn4O12 (R=Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu): A first-principles study  

NASA Astrophysics Data System (ADS)

Within RCu3Mn4O12 (R=Rare earth), besides the expected ferrimagnetic order of Mn and Cu ions below TC1, R magnetic moments also play an important role at lower temperatures TC2, leading to their peculiar magnetic behavior. By first-principles calculation, we found that along the series from La to Lu, TC1 monotonically increased due to the ionic radius (IR) induced chemical pressure, as experimentally observed, while TC2 is closely related to the atomic radius of R. Additionally, the magnetic anisotropy energy (?Eani) along the series is found to be correlated with the total magnetic moment of R ion.

Liu, Xiaojuan; Lv, Shuhui; Li, Hongping; Meng, Jian

2010-12-01

248

The system DyBr 3?DyI 3  

Microsoft Academic Search

The system DyBr3?DyI3 has been studied by differential thermal analysis (DTA), and a regular solution behaviour has been observed. For the enthalpies of fusion of DyBr3 and DyI3 the values 46.4 1.5 and 56.5 kJ mol?1, respectively, have been found.

E. H. P. Cordfunke; R. J. H. Blacquire

1997-01-01

249

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

SciTech Connect

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

Gulay, L.D. [Department of Ecology and Protection of Environment, Volyn National University, Voli Ave 13, 43009 Lutsk (Ukraine); Daszkiewicz, M., E-mail: m.daszkiewicz@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P. O. Box 1410, 50-950 WrocLaw (Poland); Shemet, V.Ya. [Department of Chemistry, Lutsk National Technical University, L'vivska str. 75, 43018 Lutsk (Ukraine)

2012-02-15

250

Crystal Packing Effects on the Magnetic Slow Relaxation of Tb(III)-Nitronyl Nitroxide Radical Cyclic Dinuclear Clusters.  

PubMed

Four lanthanide-based nitronyl nitroxide radical cyclic molecular clusters of formula [Ln(hfac)(3)(NITPhPO(OEt)(2))](2) (Ln(III) = Gd (1), Tb (2A and 2B), and Dy (3) and NITPhPO(OEt)(2) = 4'-[2-(1-oxyl-3-4,4,5,5-tetramethylimidazoline)phenyl]diethoxylphosphine oxide) have been synthesized. Their X-ray structures have been solved and highlight two different crystal packings. For the particular case of the Tb(III) derivative, both of them can be obtained. In 2A, the molecules are well-isolated, while 2B shows short contacts between N-O radical groups. Static magnetic studies on the Gd(III) derivative (1) demonstrate that lanthanides and radicals are ferromagnetically coupled (J = 3.46 0.04 cm(-1)). Dynamic magnetic studies show that both compounds 2A and 2B exhibit single molecule magnet behavior. A comparison of their magnetic behaviors highlights that the crystal packing has a crucial influence on the temperature range in which the SMM behavior is observed. In the case of the well-insulated Tb(III)-based derivative (2A), the SMM behavior is observed at higher temperatures and lower frequencies than for the one that presents close-packing between the molecules (2B). Comparisons are then possible only under an applied external magnetic field (0.2 T) with ? = 27.5(6) and 21.0(5) K and ?(0) = 2.64(25) 10(-9) and 1.76(20) 10(-9) s for 2A and 2B, respectively. PMID:23126263

Pointillart, Fabrice; Bernot, Kevin; Poneti, Giordano; Sessoli, Roberta

2012-11-01

251

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

SciTech Connect

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

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

2010-08-15

252

Crystal structure and magnetic properties of novel R3Co2.2Si1.8 compounds (R=Y, Gd-Tm)  

NASA Astrophysics Data System (ADS)

The crystal structure of new ternary Dy3Co2.2Si1.8 compound has been established using single crystal X-ray diffraction, and those of R3Co2.2Si1.8 phases (R=Y, Gd-Tm) phases have been verified through the powder diffraction techniques. The Dy3Co2.2Si1.8 structure is a new structure type, which is obtained from the Er3Ge4 with an ordered Er3Ge4-type structure (space group Cmcm) one by coloring the two Ge sites, 4a and 4c, with Si and the 8f site with Co atoms.Tb3Co2.2Si1.8, Dy3Co2.2Si1.8, Ho3Co2.2Si1.8 and Er3Co2.2Si1.8 compounds display ferromagnetic-type ordering.

Morozkin, A. V.; Yao, Jinlei; Mozharivskyj, Y.

2012-08-01

253

Tuberculosis Facts - Testing for TB  

MedlinePLUS

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

254

Tuberculosis Facts - Exposure to TB  

MedlinePLUS

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

255

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

256

Suppression of luminescence quenching at the nanometer scale in Gd2O3 doped with Eu3+ or Tb3+: Systematic comparison between nanometric and macroscopic samples of life-time, quantum yield, radiative and non-radiative decay rates  

Microsoft Academic Search

By systematically studying the evolution of the optical properties with the content of some doping elements (Eu and Tb) in cubic gadolinium oxide, we demonstrated that the luminescence quenching could be almost entirely suppressed by elaboration of the samples in the nanometer range. Indeed, even if the proportion of quenchers (here surface hydroxyl groups) does increase at this scale, each

B. Mutelet; P. Perriat; G. Ledoux; D. Amans; F. Lux; O. Tillement; C. Billotey; M. Janier; C. Villiers; R. Bazzi; S. Roux; G. Lu; Q. Gong; M. Martini

2011-01-01

257

Columinescence effect in macromolecular complexes of Eu(III) and Tb(III)  

NASA Astrophysics Data System (ADS)

The effect of Y(III) and Gd(III) coactivator ions on the intensity of Eu(III) and Tb(III) luminescence in monomer and polymer mixed-metal complexes was studied. Isomorphic replacement of Eu(III) and Tb(III) ions by Y(III) and Gd(III) ions in macromolecular complexes led to sensitization of Eu(III) and Tb(III) ion luminescence. A mechanism of columinescence was suggested. It involves a charge transfer and the ligand orbitals and the vacant orbitals of Eu(III) and Tb(III) ions and coactivators.

Petrochenkova, N. V.; Mirochnik, A. G.; Zhikhareva, P. A.; Karasev, V. E.

2010-09-01

258

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

259

The phase transition of the incommensurate phases beta-Ln(PO{sub 3}){sub 3}(Ln=Y,Tb...Yb), crystal structures of alpha-Ln(PO{sub 3}){sub 3}(Ln=Y,Tb...Yb) and Sc(PO{sub 3}){sub 3}  

SciTech Connect

The incommensurately modulated room-temperature phases beta-Ln(PO{sub 3}){sub 3}(Ln=Y,Tb...Yb) undergo a topotactic phase transition monitored by vibrational spectroscopy below 180 K leading to alpha-Ln(PO{sub 3}){sub 3}(Ln=Y,Dy...Yb), above 200 K the incommensurate phases are reobtained. The low-temperature phases exhibit a new structure type (alpha-Dy(PO{sub 3}){sub 3},P2{sub 1}/c,Z=12,a=14.1422(6),b=20.0793(9),c=10.1018(4)A, beta=127.532(3){sup 0}). alpha-Tb(PO{sub 3}){sub 3} is isotypic with Gd(PO{sub 3}){sub 3}(alpha-Tb(PO{sub 3}){sub 3},I2/a,Z=16,a=25.875(6),b=13.460(3),c=10.044(2)A, beta=119.13(3){sup 0}). The symmetry relations between the involved phases of the phase transition are discussed. The crystal structure of Sc(PO{sub 3}){sub 3} is isotypic with that of Lu(PO{sub 3}){sub 3} and C-type phosphates. The polyphosphates consist of infinite zig-zag chains of corner-sharing PO{sub 4} tetrahedra, the cations are coordinated sixfold in an almost octahedral arrangement. To confirm the quality of the determined crystal structures the deviation of the phosphate tetrahedra from ideal symmetry was determined and discussed. - Abstract: Basic structure from which all crystal structures of the late lanthanoids' polyphosphates at room temperature and below can be derived.

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

2009-07-15

260

Nuclear orientation of sup 160 Tb in Tb single crystal  

SciTech Connect

Nuclear orientation of {sup 160}Tb in a Tb single crystal has been carried out in order to obtain accurate values of multipole mixing ratios for 22 transitions in {sup 160}Dy. The experimental aspects are described in some detail as they form the basis for obtaining high quality data. Three different methods were used to extract the mixing ratios, and they are shown to agree very well. Our results for both {ital E}1/{ital M}2 and {ital E}2/{ital M}1 transitions are compared to other measurements. The signs and magnitude of the {ital E}1/{ital M}2 mixing ratios cannot be explained on the basis of Coriolis mixing of the {ital K}=0, 1, and 2 bands. Comparison of our results for the 299, 1178, and 1272 keV transitions with those from {gamma}-{gamma} directional correlation measurements indicate that some {ital E}3 admixture may be present in these transitions. The mixing ratios we obtained for the {ital E}2/{ital M}1 transitions are in reasonably good agreement with the predictions of the interacting-boson-approximation-1 model.

Marshak, H. (National Bureau of Standards, Gaithersburg, Maryland 20899 (US)); Brewer, W.D.; Roman, P. (Fachbereich Physik, Freie Universitaet Berlin, Berlin 33, Germany)

1989-10-01

261

Suppression of luminescence quenching at the nanometer scale in Gd2O3 doped with Eu3+ or Tb3+: Systematic comparison between nanometric and macroscopic samples of life-time, quantum yield, radiative and non-radiative decay rates  

NASA Astrophysics Data System (ADS)

By systematically studying the evolution of the optical properties with the content of some doping elements (Eu and Tb) in cubic gadolinium oxide, we demonstrated that the luminescence quenching could be almost entirely suppressed by elaboration of the samples in the nanometer range. Indeed, even if the proportion of quenchers (here surface hydroxyl groups) does increase at this scale, each rare-earth cation possesses an electronic configuration that depends on its distance from the surface and then slightly differs from that of the surrounding atoms. This difference almost eliminates any resonant transfer of excitation between all the atoms within the particle and suppresses a significant proportion of non-radiative losses. As a consequence, the quantum yield is not affected by the phenomenon of luminescence quenching because of concentration that is usually encountered in macroscopic samples. The emission can then be increased by a factor of about 3 for Tb and 5 for Eu simply by increasing the doping content. Moreover, the lifetime is significantly increased compared to macroscopic samples and, contrary to what happens at the macroscopic scale, does not depend on the doping content. This result opens new strategies to increase the emission of many fluorophores already commercialized, provided that the bcc structure is effectively preserved in the desired application.

Mutelet, B.; Perriat, P.; Ledoux, G.; Amans, D.; Lux, F.; Tillement, O.; Billotey, C.; Janier, M.; Villiers, C.; Bazzi, R.; Roux, S.; Lu, G.; Gong, Q.; Martini, M.

2011-11-01

262

Multi-quasiparticle excitations in145Tb  

NASA Astrophysics Data System (ADS)

High-spin states in145Tb have been populated using the118Sn (32S, 1p4n) reaction at beam energy of 165 MeV. The level scheme of145Tb has been established up to Ex?7.4 MeV. The level scheme shows characteristics of a spherical or slightly oblate nucleus. Based on the systematic trends of the level structure in the neighboring N=80 isotones, the level structure in145Tb below 2 MeV excitation is well eplained by coupling an h 11/2 valence proton to the even-even144Gd core. Above 2 MeV excitation, most of the yrast levels are interpreted with multi-quasiparticle shell-model configurations.

Zheng, Yong; Zhou, Xiaohong; Zhang, Yuhu; Liu, Minliang; Guo, Yingxiang; Lei, Xiangguo; Hayakawa, T.; Oshima, M.; Toh, T.; Shizuma, T.; Katakura, J.; Hatsukawa, Y.; Matsuda, M.; Kusakari, H.; Sugawara, M.

2004-09-01

263

Structural trends in a series of isostructural lanthanide-copper metallacrown sulfates (Ln(III) = Pr, Nd, Sm, Eu, Gd, Dy and Ho): hexaaquapentakis[?3-glycinehydroxamato(2-)]sulfatopentacopper(II)lanthanide(III) heptaaquapentakis[?3-glycinehydroxamato(2-)]sulfatopentacopper(II)lanthanide(III) sulfate hexahydrate.  

PubMed

The seven isostructural complexes, [Cu(5)Ln(C(2)H(4)N(2)O(2))(5)(SO(4))(H(2)O)(6.5)](2)(SO(4))6H(2)O, where Ln(III) = Pr, Nd, Sm, Eu, Gd, Dy and Ho, are representatives of the 15-metallacrown-5 family. Each dianion of glycinehydroxamic acid (GlyHA) links two Cu(II) cations forming a cyclic [CuGlyHA](5) frame. The Ln(III) cations are located at the centre of the [CuGlyHA](5) rings and are bound by the five hydroxamate O atoms in the equatorial plane. Five water molecules are coordinated to Cu(II) cations, and one further water molecule, located close to an inversion centre between two adjacent [Cu(5)Ln(GlyHA)(5)](2+) cations, is disordered around this inversion centre and coordinated to a Cu(II) cation of either the first or second metallacrown ether. Another water molecule and one of the two crystallographically independent sulfate anions are coordinated, the latter in a bidentate fashion, to the Ln(III) cation in the axial positions. The second sulfate anion is not coordinated to the cation, but is located in an interstitial position on a crystallographic inversion centre, thus leading to disorder of the O atoms around the centre of inversion. The Ln-O bond distances follow the trend of the lanthanide contraction. The apical Ln-O bond distances are very close to the sums of the ionic radii. However, the Ln-O distances within the metallacrown units are slightly compressed and the Ln(III) cations protrude significantly from the plane of the otherwise flat metallacrown ligand, thus indicating that the cavity is somewhat too small to accommodate the Ln(III) ions comfortably. This effect decreases with the size of the lanthanide cation from complex (I) (Ln(III) = Pr; 0.459) to complex (VII) (Ln(III) = Ho; 0.422), which indicates that the smaller lanthanide cations fit the cavity of the pentacopper metallacrown ring better than the larger ones. The diminished contraction of Ln-O distances within the metallacrown planes leads to an aniostropic contraction of the unit-cell parameters, with a, c and V following the trend of the lanthanide contraction. The b axes, which are mostly aligned with the rigid planes of the metallacrown units, show only a little variation between the seven compounds. PMID:21727626

Pavlishchuk, Anna V; Kolotilov, Sergey V; Fritsky, Igor O; Zeller, Matthias; Addison, Anthony W; Hunter, Allen D

2011-06-29

264

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

PubMed

A series of isostructural octanuclear lanthanide complexes of general formula [Ln8(sao)4(?3-OH)4(NO3)12(DMF)12] (Ln = Nd (), Sm (), Eu (), Gd (), Tb (), Dy (), Ho (), Er (); DMF = dimethylformamide) have been prepared via reactions of salicylaldoxime (saoH2), tetramethylammonium hydroxide (Me4NOH) with the appropriate lanthanide nitrate salt (Ln(NO3)36H2O). The metallic skeletons of the complexes describe [Ln4] tetrahedra encapsulated inside a [Ln4] square with the inner core stabilised through ?3-OH(-) ions and the periphery by ?4-sao(2-) ligands. The magnetic properties of compounds were investigated by dc and ac magnetometry. Temperature dependent ac magnetic susceptibility data reveal that the dysprosium analogue () displays an out-of-phase signal in the absence of an applied magnetic field indicative of slow relaxation of the magnetization typical of a Single-Molecule Magnet (SMM). Micro-SQUID measurements reveal temperature and sweep rate dependent hysteresis below 1.0 K. PMID:23943045

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

2013-10-01

265

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

PubMed

The sequential reaction of a phosphorus-based trishydrazone ligand, LH3 with anhydrous ZnCl2 and LnCl36H2O in a 2?:?2?:?1 stoichiometric ratio in the presence of triethylamine as the base leads to the formation of monocationic trinuclear complexes [L2Zn2Ln]Cl {Ln = Gd (), Tb (), Nd (), Eu () and L = [(S)P[N(Me)N[double bond, length as m-dash]CH-C6H3-2-O-3-OMe]3}. All the three metal ions, in each of these compounds, are arranged in a linear fashion. The two terminal Zn(ii) ions are encapsulated by three imino and three phenolate oxygen atoms while the lanthanide ion remains in the centre with an all-oxygen coordination environment. Detailed photophysical measurements reveal the complete absence of antenna sensitization in all the four complexes. However, a strong emission was found for and when excited directly at their f-f levels. PMID:24018551

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

2013-10-15

266

TB in disasters  

Microsoft Academic Search

In the developing world it is well known that di- sasters impact TB. Poor nutrition and overcrowding typical of refugee and displaced settings encourage the development and spread of TB, while access to TB control programmes may be reduced due to dis- rupted health care services and population displace- ment. Health care may be provided by international aid agencies that

Nathan Ford; Vinciane Sizaire

267

Rotational bands of 156Gd  

NASA Astrophysics Data System (ADS)

High-spin states of 156Gd have been studied by using the reaction 150Nd(13C/,?3n). The ground-state band, /? band, and octupole band have been extended up to 26+, 16+, and 21- states respectively. Gamma-ray branchings between E2 decays down the K=1- band and E1 decays across to the ground band are discussed on the basis of the Generalized Intensity Relations. It is found that the /B(E1)/B(E2) ratios have the maximum value at the intermediate spin. This feature is quite similar to the the case of the lowest octupole K=0- band in 238U and is not yet resolved. Moreover a new band in the spin range of /(10,11)<=I<=(20,21) was observed, whose /?-rays turned out to be almost identical in energy to the ones found in the isotone 158Dy.

Sugawara, M.; Mitarai, S.; Kusakari, H.; Oshima, M.; Hayakawa, T.; Toh, Y.; Hatsukawa, Y.; Katakura, J.; Iimura, H.; Zhang, Y. H.; Sugie, M.; Sato, Y.

2001-04-01

268

Tuberculosis Facts - TB and HIV/AIDS  

MedlinePLUS

... STD, and TB Prevention Division of Tuberculosis Elimination Tuberculosis (TB) Facts TB and HIV/AIDS What is TB? TB is short for a disease called tuberculosis. TB is spread through the air from one ...

269

Tuberculosis Facts - TB Can Be Treated  

MedlinePLUS

... STD, and TB Prevention Division of Tuberculosis Elimination Tuberculosis (TB) Facts TB Can Be Treated What is TB? TB is short for a disease called tuberculosis. TB is spread through the air from one ...

270

Tuberculosis Facts - You Can Prevent TB  

MedlinePLUS

... STD, and TB Prevention Division of Tuberculosis Elimination Tuberculosis (TB) Facts You Can Prevent TB What is TB? TB is short for a disease called tuberculosis. TB is spread through the air from one ...

271

Identification of 161Sm and 165Gd  

NASA Astrophysics Data System (ADS)

Two new neutron-rich rare-earth isotopes 161Sm and 165Gd produced in the proton-induced fission of 238U were identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport system. The half-lives were determined to be 4.8+/-0.8 s for 161Sm and 10.3+/-1.6 s for 165Gd. The assignment of these isotopes was based upon the observation of Eu and Tb K x rays in the ?-gated x/?-ray spectra measured for the separated mass fraction 177 and 181 as monoxide ions 161Sm16O+ and 165Gd16O+, respectively.

Ichikawa, S.; Tsukada, K.; Nishinaka, I.; Hatsukawa, Y.; Iimura, H.; Hata, K.; Nagame, Y.; Osa, A.; Asai, M.; Kojima, Y.; Hirose, T.; Shibata, M.; Kawade, K.; Oura, Y.

1998-08-01

272

Multi-quasiparticle excitations in 145Tb  

NASA Astrophysics Data System (ADS)

High-spin states in 145Tb have been investigated by means of in-beam ggr-ray spectroscopy techniques with the 118Sn(32S, 1p4n) reaction. Excitation functions, X-ggr-t and ggr-ggr-t coincidences and ggr-ray anisotropies were measured. A level scheme of 145Tb was established up to Exap 7 MeV. The level structure shows characteristics of a spherical nucleus. Based on the systematics of level structure in the odd-A N = 80 isotones, the level structure below 2 MeV excitation is interpreted by coupling an h11/2 proton to the excitations in the even-even 144Gd core. Above 2 MeV excitation, most of the yrast levels are interpreted with multi-quasiparticle shell-model configurations.

Zheng, Y.; Zhou, X. H.; Zhang, Y. H.; Hayakawa, T.; Oshima, M.; Toh, Y.; Shizuma, T.; Katakura, J.; Hatsukawa, Y.; Matsuda, M.; Kusakari, H.; Sugawara, M.; Furuno, K.; Komatsubara, T.

2004-04-01

273

[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; Oberthr, W; Braunitzer, G

1983-11-01

274

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

275

Benzoxazole-based heterometallic dodecanuclear complex [Dy(III)4Cu(II)8] with single-molecule-magnet behavior.  

PubMed

Three Cu-Ln (Ln = Dy, Gd, Y) dodecanuclear clusters assembled by a novel ligand of the benzoxazole type are reported. The dysprosium cluster exhibits a frequency dependence of the alternating-current susceptibility and hysteresis loop at low temperature, indicating single-molecule-magnet behavior. PMID:21749109

Iasco, Olga; Novitchi, Ghenadie; Jeanneau, Erwann; Wernsdorfer, Wolfgang; Luneau, Dominique

2011-07-12

276

Magneto-optic characteristics of BiTbGaIG film/TbYbBiIG bulk crystal composite structure in 1550 nm band  

NASA Astrophysics Data System (ADS)

Using Tb0.85Yb1.62Bi0.53Fe5O12 (TbYbBiIG) instead of the conventional nonmagnetic Gd3Ga5O12, Tb2.43Bi0.57Ga0.1Fe4.9O12 (TbBiGaIG) films were grown on the TbYbBiIG substrate. Excellent magneto-optical characteristics were obtained in the TbBiGaIG/TbYbBiIG composite structure: 4?Ms=0.48106 A/m, ?f=-1117.2 deg/cm at ?=1550 nm (Faraday rotation wavelength coefficient) FWC=0.049%/nm in the wavelength range of 1550-1620 nm at 25 C, and Faraday rotation temperature coefficient FTC=-5.4810-5 deg/K at ?=1550 nm. The TbYbBiIG with low FWC and FTC could be obtained due to the compensation effect. The TbBiGaIG layer with a compensation temperature centered in the operating temperature range creates a step function in Faraday rotation, and subsequently reduces the net change of Faraday rotation caused by the temperature dependence of TbYbBiIG substrate.

Xu, Z. C.

2006-07-01

277

Study of the first excited K{sup {pi}}=0{sup +} band in {sup 162}Dy  

SciTech Connect

There has been recently much discussion about the nature of the first excited K{sup {pi}}=0{sup +} band in deformed nuclei. An experiment {sup 159}Tb({alpha},n) {sup 162}Ho was conducted at Yale to study the K{sup {pi}}=0{sub 2}{sup +} band in {sup 162}Dy. Preliminary data analysis results of the experiment and future plans with the moving tape collector (MTC) will be discussed.

Liu Benyuan; Casten, R. F.; Beausang, C. W.; Kruecken, R.; Cooper, J. R.; Novak, J. R. [WNSL, Yale University, New Haven, Connecticut 06520 (United States); Zamfir, N. V. [WNSL, Yale University, New Haven, Connecticut 06520 (United States); Clark University, Worcester, Massachusetts 01610 (United States); Institute of Atomic Physics, Bucharest Magurele (Romania); Brenner, D. S.; Barton, C. J. [Clark University, Worcester, Massachusetts 01610 (United States); Cata-Danil, G. [WNSL, Yale University, New Haven, Connecticut 06520 (United States); Institute of Atomic Physics, Bucharest Magurele (Romania); Gill, R. L. [Brookhaven National Laboratory, Upton, New York 11973 (United States)

1998-12-21

278

Study of the first excited K{sup {pi}}=0{sup +} band in {sup 162}Dy  

SciTech Connect

There has been recently much discussion about the nature of the first excited K{sup {pi}}=0{sup +} band in deformed nuclei. An experiment {sup 159}Tb({alpha},n){sup 162}Ho was conducted at Yale to study the K{sup {pi}}=0{sub 2}{sup +} band in {sup 162}Dy. Preliminary data analysis results of the experiment and future plans with the moving tape collector (MTC) will be discussed. {copyright} {ital 1998 American Institute of Physics.}

Liu, Benyuan; Zamfir, N.V.; Casten, R.F.; Cata-Danil, G.; Beausang, C.W.; Krucken, R.; Cooper, J.R.; Novak, J.R. [WNSL, Yale University, New Haven, Connecticut 06520 (United States); Brenner, D.S.; Barton, C.J. [Clark University, Worcester, Massachusetts 01610 (United States); Cata-Danil, G. [Institute of Atomic Physics, Bucharest Magurele (Romania)] Gill, R.L. [Brookhaven National Laboratory, Upton, New York 11973 (United States)

1998-12-01

279

Superdeformed band in 148Gd: A test of shell effects in the mass-150 region  

Microsoft Academic Search

A discrete superdeformed band was found in 148Gd, and was produced both in Ca- and Si-induced compound-nucleus reactions. It is the third band found in the mass-150 region and its properties provide the clearest indication that 152Dy is a ``magic'' superdeformed nucleus.

M. A. Deleplanque; C. Beausang; J. Burde; R. M. Diamond; J. E. Draper; C. Duyar; A. O. Macchiavelli; R. J. McDonald; F. S. Stephens

1988-01-01

280

Synthesis And Characterization Of Gd2O3: Tb 30%  

NASA Astrophysics Data System (ADS)

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

Djebara, Abdelhakim; Halimi, Rachid

2008-09-01

281

Electrical resistivity and magnetic investigations of the orthorhombic Tb(Ni, Cu)2 system  

Microsoft Academic Search

The orthorhombic Tb(Ni, Cu)2 and Gd(Ni, Cu)2 systems (CeCu2 structure) are closely similar according to electrical resistivity and magnetic results. The Tb(NixCu1-x)2 system presents a transition from antiferromagnetism (AF) for x <= 8% Ni to ferromagnetism (FM) for x > 8% Ni. The CeCu2 structure becomes unstable for x > 45% Ni. The AF samples show metamagnetism at 4.2 K

C. A. Poldy; E. Gratz

1978-01-01

282

Mbauereffekt in 157 Gd und 155 Gd  

Microsoft Academic Search

Using the Mssbauer technique electric hyperfine interactions of the first excited non-rotational states at 64 keV in157Gd and at 86.5 keV in155Gd have been determined in GdF3 and GdCl3 6H2O. For the ratio of quadrupolmoments the ratiosQ64157\\/Qg157=1.740.04,Q86.5155\\/Qg157=-0.07 0.21 andQg155\\/Qg157=0.78 0.06 were found. In addition isomer shifts were observed from which a ratio d2>64157\\/d2>86.5155=-2.60.15 can be inferred.

Heinz Prange

1968-01-01

283

On the magnetic dipole moment of the 153 Tb ground state  

Microsoft Academic Search

Temperature dependence of the angular distribution anisotropy of the 2120 keV gamma-ray following the decay of153Tb oriented in a gadolinium host was measured at temperatures from 16 to 70 mK. Magnetic dipole hyperfine splitting parameter a0 for153Tb(Gd) and magnetic dipole moment of the153Tb ground state were estimated to be a0?1210-5 eV and ??31 nuclear magnetons, respectively.

I. Prochzka; J. Koncek; J. Dupk; M. Finger; M. I. Fominykh; T. I. Krackov; V. N. Pavlov; M. Petrk; V. M. Tsupko-Sitnikov; J. Muhonen

1981-01-01

284

Slow dynamics of Dy pyrochlore oxides Dy2Sn2O7 and Dy2Ir2O7  

NASA Astrophysics Data System (ADS)

We report the magnetic properties of Dy pyrochlore oxides, Dy2Sn2O7 and Dy2Ir2O7. We show that the temperature dependence of the relaxation time ?(T) in the case of Dy2Sn2O7 is very similar to that in the case of a typical spin ice, Dy2Ti2O7. However, the time scale of Dy2Sn2O7 is 10-100 times slower than that of Dy2Ti2O7 over the entire temperature range. Dy2Ir2O7 exhibits a metal-insulator transition at 134 K; it has a broad peak at 4.5 K in the DC magnetic susceptibility, indicating an antiferromagnetic correlation. However, the specific heat has no sharp anomaly at 4.5 K. We show that the Dy moments in Dy2Ir2O7 have no long-range ordering down to 100 mK. We elucidate the anomalous slow dynamics that ?(T) decreases and becomes inhomogeneous below 12 K.

Matsuhira, Kazuyuki; Wakeshima, Makoto; Hinatsu, Yukio; Sekine, Chihiro; Paulsen, Carley; Sakakibara, Toshiro; Takagi, Seishi

2011-09-01

285

Atomic structure of Tb(11 2 0)  

SciTech Connect

A low-energy electron-diffraction intensity analysis of a Tb(11{bar 2}0) surface finds that the atomic structure of this surface is different from bulk structure in two ways: The spacing between the first and the second layer, which have two inequivalent atoms in the unit mesh, is contracted by 3.3% (0.06 A), and the two inequivalent atoms in the first layer translate parallel to the surface by equal and opposite amounts of 0.21 A. Thus the change in registration of the composite surface layer preserves both the size and the symmetry of the unit mesh of parallel bulk layers. This kind of surface rearrangement is different from that reported by others for the (11{bar 2}0) surfaces of other rare-earth metals, such as Y, Gd, and Ho.

Li, Y.S.; Quinn, J.; Jona, F. (College of Engineering and Applied Science, State University of New York, Stony Brook, New York 11794 (United States)); Marcus, P.M. (IBM Research Center, Yorktown Heights, New York 10598 (United States))

1992-08-15

286

(Dy[sub 0. 5]Er[sub 0. 5])Al[sub 2]: A large magnetocaloric effect material for low-temperature magnetic refrigeration  

SciTech Connect

The low-temprature heat capacity and ac and dc magnetic properties of (Dy[sub 0.5]Er[sub 0.5])Al[sub 2] have been studied as a function of magnetic fields up to [similar to]10 T. The magnetocaloric effect in (Dy[sub 0.5]Er[sub 0.5])Al[sub 2] is 30% larger than that of the prototype material, GdPd. Magnetic measurements show that there is no measurable magnetic hysteresis above [similar to]17 K. These results suggest that (Dy[sub 0.5]Er[sub 0.5])Al[sub 2] would be a significantly better magnetic refrigerant than GdPd.

Gschneidner, K.A. Jr.; Takeya, H.; Moorman, J.O.; Pecharsky, V.K. (Ames Laboratory and Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011-3020 (United States))

1994-01-10

287

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

SciTech Connect

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

Vitaliy Vladislavovich Ivchenko

2002-07-19

288

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

289

Specific features of the crystal structure and magnetic properties of the DyFeTi2O7 compound  

NASA Astrophysics Data System (ADS)

Results of studying the specific features of formation of the crystal structure and distribution of iron cations over the sites in the DyFeTi2O7 compound have been presented and the comparison with the GdGaTi2O7 isostructural compound has been performed. The atomic disorder in the distribution of the Fe3+ ions over structural sites in the DyFeTi2O7 compound is confirmed by the Mssbauer spectroscopy and X-ray diffractometry. The results of magnetic measurements in the low-temperature region have revealed an inflection point in the temperature dependence of the magnetic moment and its dependence on the magnetic prehistory of the sample. The obtained experimental data suggest that there is a spin glass state with freezing point T f = 6 K in the DyFeTi2O7 compound.

Drokina, T. V.; Petrakovskii, G. A.; Molokeev, M. S.; Velikanov, D. A.; Pletnev, O. N.; Bayukov, O. A.

2013-10-01

290

Ternary Dy-Er-Al magnetic refrigerants  

SciTech Connect

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

291

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

292

Phase formation in the systems Li2MoO4 K2MoO4 Ln2(MoO4)3 (Ln=La, Nd, Dy, Er) and properties of triple molybdates LiKLn2(MoO4)4  

NASA Astrophysics Data System (ADS)

Subsolidus phase relations in the systems Li2MoO4 K2MoO4 Ln2(MoO4)3 (Ln=La, Nd, Dy, Er) were determined. Formation of LiKLn2(MoO4)4 was confirmed in the systems with Ln=Nd, Dy, Er at the LiLn(MoO4)2 KLn(MoO4)2 joins. No intermediate phases of other compositions were found. No triple molybdates exist in the system Li2MoO4 K2MoO4 La2(MoO4)3. The join LiLa(MoO4)2 KLa(MoO4)2 is characterized by formation of solid solutions. Triple molybdates LiKLn2(MoO4)4 for Ln=Nd Lu, Y were synthesized by solid state reactions (single phases with ytterbium and lutetium were not prepared). Crystal and thermal data for these molybdates were determined. Compounds LiKLn2(MoO4)4 form isostructural series and crystallized in the monoclinic system with the unit cell parameters a=5.315 5.145 , b=12.857 12.437 , c=19.470 19.349 , ?=92.26 92.98. When heated, the compounds decompose in solid state to give corresponding double molybdates. The dome-shaped curve of the decomposition temperatures of LiMLn2(MoO4)4 has the maximum in the Gd Tb Dy region. While studying the system Li2MoO4 K2MoO4 Dy2(MoO4)3 we revealed a new low-temperature modification of KDy(MoO4)2 with the triclinic structure of ?-KEu(MoO4)21Hereinafter, ? refers to a low-temperature modification. (a=11.177(2) , b=5.249(1) , c=6.859(1) , ?=112.33(2), ?=111.48(1), ?=91.30(2), space group P1, Z=2).Graphical abstractSubsolidus phase diagrams of some Li2MoO4 K2MoO4 Ln2(MoO4)3 systems. S=LiKLn2(MoO4)4.

Basovich, O. M.; Khaikina, E. G.; Solodovnikov, S. F.; Tsyrenova, G. D.

2005-05-01

293

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

PubMed

Radiation synovectomy is an effective treatment in patients suffering from inflammatory-rheumatoid and degenerative joint diseases. The aim of this work was to examine the feasibility of preparing dysprosium-166 (166Dy)/holmium-166(166Ho) hydroxide macroaggregates ([166Dy]Dy/166Ho-HM) as an in vivo generator for radiation synovectomy evaluating whether the stability of 166Dy-HM and 166Ho-HM complexes is maintained when the daughter 166Ho is formed. The Monte Carlo (MCNP4B) theoretical depth dose profile for the in vivo [166Dy]Dy/166Ho generator system in a joint model was calculated and compared with that produced by 90Y, 153Sm and 166Ho. 166Dy was obtained by neutron irradiation of enriched 164Dy2O3 in a Triga Mark III reactor. Macroaggregates were prepared by reaction of [166Dy]DyCl3 with 0.5 M NaOH in an ultrasonic bath. [166Dy]Dy/166Ho-HM was obtained with radiochemical purity >99.5% and with the majority of particles in the 2-5 microm range. In vitro studies demonstrated that the radio-macroaggregates are stable in saline solution and human serum without a significant change in the particle size over 14 d, suggesting that no translocation of the daughter nucleus occurs subsequent to beta- decay of 166Dy. Biological studies in normal rats demonstrated high retention in the knee joint even 7 d after [166Dy]Dy/166Ho-HM administration. The Monte Carlo (MCNP4B) theoretical depth dose profiles in a joint model, showed that the in vivo [166Dy]Dy/166Ho generator system would produce 25% and 50% less radiation dose to the articular cartilage and bone surface, respectively, than that produced by 90Y or pure 166Ho in a treatment with the same therapeutic dose to the synovium surface. Despite that 153Sm showed the best depth dose profile sparing doses to healthy tissues, the use of 166Dy could provide the advantage of being applied in patients that cannot be reached within a few hours from a nuclear reactor and to produce less radiation exposure to the medical personnel during the radiopharmaceutical administration. PMID:15388114

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

2004-12-01

294

g -factors of the ground state rotational band of 158 Dy  

Microsoft Academic Search

Theg-factors of the four lowest states of the ground state rotational band of158Dy have been determined asg(21+)=+0.362(23),g(41su+)=+0.340(20),g(61su+)=+0.207(36) andg(81su+)=+0.21(11). Theg-factors of the 2+ and 4+ states were measured by the IPAC method with radioactive samples of 2.4 h158Er in external magnetic fields. To investigate the higher states, for the first time an on-line ?? IPAC experiment was performed with the reaction156Gd(a,

I. Alfter; E. Bodenstedt; B. Hamer; J. van den Hoff; W. Knichel; H. Mnning; S. Piel; R. Sajok; J. Schth

1993-01-01

295

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

Microsoft Academic Search

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

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

1968-01-01

296

Thermal neutron cross-section and resonance integral for 164Dy(n,?) 165Dy reaction  

Microsoft Academic Search

The thermal neutron cross-section (?0) and the resonance integral (I0) of the reaction 164Dy(n,?)165Dy were measured by the activation method, using 55Mn(n,?)55Mn monitor reaction as a single comparator. The diluted MnO2 and Dy2O3 powder samples within and without a cylindrical Cd shield case were irradiated in an isotropic neutron field obtained from the 241AmBe neutron sources, moderated with paraffin wax.

Mustafa Karadag; Haluk Ycel

2005-01-01

297

Molecular assembly and magnetic dynamics of two novel Dy6 and Dy8 aggregates.  

PubMed

Complexation of dysprosium(III) with the heterodonor chelating ligand o-vanillin picolinoylhydrazone (H(2)ovph) in the presence of a carbonato ligand affords two novel Dy(6) and Dy(8) clusters, namely, [Dy(6)(ovph)(4)(Hpvph)(2)Cl(4)(H(2)O)(2)(CO(3))(2)]CH(3)OHH(2)OCH(3)CN (2) and [Dy(8)(ovph)(8)(CO(3))(4)(H(2)O)(8)]12CH(3)CN6H(2)O (3). Compound 2 is composed of three petals of the Dy(2) units linked by two carbonato ligands, forming a triangular prism arrangement, while compound 3 possesses an octanuclear core with an unprecedented tub conformation, in which Dy(ovph) fragments are attached to the sides of the carbonato core. The static and dynamic magnetic properties are reported and discussed. In the Dy(6) aggregate, three Dy(2) "skeletons", having been well preserved (see the scheme), contribute to the single-molecule-magnet behavior with a relatively slow tunneling rate, while the Dy(8) cluster only exhibits a rather small relaxation barrier. PMID:22432447

Guo, Yun-Nan; Chen, Xiao-Hua; Xue, Shufang; Tang, Jinkui

2012-03-20

298

Asteroids Dynamic Site-AstDyS  

NASA Astrophysics Data System (ADS)

The AstDyS online information service (http://hamilton.dm.unipi.it/astdys/) contains data on numbered and multi - opposition asteroids, including orbital elements, their uncertainty, proper elements, ephemerides with uncertainty, and more. AstDyS also provides additional scientific output computed from the raw observational data. This value added currently includes: more accurate orbits computed with advanced dynamical and observational error model s; their uncertainty, as expressed by the covariance matrix formalism; ephemerides computed on request for each observer, with uncertainty; mean and proper orbital elements (for this output, AstDyS is the primary source worldwide); statistical quality control, providing a rigorous observational error model. All this is available with a sophisticated web interface, providing multiple search functions and online computations as well as complete orbital and residual files. There are several ways in which the A stDyS service could be expanded and improved in the next future, like the explicit classification of asteroids into asteroid families, the classification of resonant asteroids, and an updated self - consistent population model (to be used, e.g., for survey simulations). The IAU Division I endorsed the proposal for AstDyS to become an IAU (permanent) service, which would include the IAU supervision of the AstDyS system, keeping under control the quality of the work and the continuous update under conditions of scientific competition.

Knezevic, Zoran; Milani, Andrea

2012-08-01

299

Rotational bands of 159Dy  

NASA Astrophysics Data System (ADS)

High-spin states of 159Dy have been studied by using reaction 150Nd(13C,4n). Two rotational bands based on the configurations /?[521]3/2 and /?[642]5/2 have been extended to 57/2- and 61/2+ states, respectively. A neutron AB crossing has been observed around /??=0.26 MeV in the /?[521]3/2 band. It has been observed that the signature splitting is inverted after the band crossing in the /?[521]3/2 band. The first band crossing has been observed around /??=0.38 MeV in the /?[642]5/2 band. Seven E1 transitions from the /?[521]3/2 band to the /?[642]5/2 band have been observed and discussed on the base of Generalized Intensity Relation. It is found that the /B(E1)/B(E2) ratios for 47/2- and 43/2- states become enhanced relatively to those for the lower-spin states.

Sugawara, M.; Mitarai, S.; Kusakari, H.; Oshima, M.; Hayakawa, T.; Toh, Y.; Hatsukawa, Y.; Katakura, J.; Iimura, H.; Zhang, Y. H.; Sugie, M.; Sato, Y.

2002-03-01

300

Unexpected Decrease in Moment of Inertia Between N = 98 - 100 IN 162,164GD  

NASA Astrophysics Data System (ADS)

From prompt ? - ? - ? coincidence studies with a 252Cf source, the yrast levels were identified from 2+ to 16+ and 14+ in neutron-rich 162,164Gd, respectively. Transition energies between the same spin states are higher and moments of inertia lower at every level in N = 100 164Gd than in N = 98 162Gd. The same trend is seen in 164,166Dy. These observations are in contrast to the continuous decrease in the 2+ energy to a minimum at neutron midshell (N = 104) in Er, Yb, and Hf nuclei. The lowest known 2+ energy in this region now occurs for N = 96 156Nd and next for N = 98 160Sm, which are well removed from midshell for both protons and neutrons.

Jones, E. F.; Hamilton, J. H.; Gore, P. M.; Ramayya, A. V.; Hwang, J. K.; Delima, A. P.; Zhu, S. J.; Luo, Y. X.; Beyer, C. J.; Kormicki, J.; Zhang, X. Q.; Ma, W. C.; Lee, I. Y.; Rasmussen, J. O.; Wu, S. C.; Ginter, T. N.; Fallon, P.; Stoyer, M.; Cole, J. D.; Daniel, A. V.; Ter-Akopian, G. M.; Donangelo, R.

2005-03-01

301

Lifetime measurements and shape coexistence in {sup 144}Dy  

SciTech Connect

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

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

2010-05-15

302

Observation of excited proton and neutron configurations in the superdeformed sup 149 Gd nucleus  

SciTech Connect

Two excited superdeformed bands in {sup 149}Gd have been observed in {gamma}-ray spectroscopy. Based on the behavior of the dynamical moments of inertia, we assign one band to a neutron excitation and the other to a proton excitation. The proton-excited-band {gamma}-ray energies are nearly identical to those already known in {sup 150}Tb. In addition, two new members of the {sup 149}Gd yrast cascade have been observed, extending the band to spin 135/2{h bar}. The results are discussed in terms of high-{ital N} intruder orbitals in the cranked-shell model.

Haas, B.; Ward, D.; Andrews, H.R.; Ball, G.C.; Drake, T.E.; Flibotte, S.; Galindo-Uribarri, A.; Janzen, V.P.; Johansson, J.K.; Kluge, H.; Kuehner, J.; Omar, A.; Pilotte, S.; Prevost, D.; Rodriguez, J.; Radford, D.C.; Taras, P.; Vivien, J.P.; Waddington, J.C.; Aberg, S. (Centre de Recherches Nucleaires, Strasbourg (France) Atomic Energy of Canada Limited, Chalk River Nuclear Laboratories, Chalk River, Ontario (Canada) Department of Physics, University of Toronto, Toronto, Ontario (Canada) Laboratoirede Physique Nucleaire, Universite de Montreal, Quebec (Canada) Departmentof Physics, McMaster University, Hamilton, Ontario (Canada) Hahn-Meitner-Institut, Berlin (West Germany) Department of Physics and Astronomy,University of Tennessee, Knoxville, TN (USA) Department of Mathematical Physics, Lund Institute of Technology, Lund (Sweden))

1990-11-01

303

TB deaths reach historic levels. International (global).  

PubMed

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

304

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

305

Bonding anisotropy in multiferroic TbMnO3 probed by polarization dependent x-ray absorption spectroscopy  

NASA Astrophysics Data System (ADS)

O K- and Mn L2,3-edges x-ray absorption spectra of orthorhombic TbMnO3 single crystals show strong polarization dependence, in contrast with results of previous experiments on orthorhombic LaMnO3 and DyMnO3 thin films that show nearly isotropic spectral structure. First-principles calculations reveal that TbMnO3 exhibits a zigzag eg orbital ordering ground state. The highly distorted MnO6 octahedron and orbital ordering in TbMnO3 produce highly anisotropic Mn-O bonding within the ab plane, a frustration of the magnetic ordering, and the formation of complicated incommensurate magnetic structures.

Chen, J. M.; Lee, J. M.; Chen, C. K.; Chou, T. L.; Lu, K. T.; Haw, S. C.; Liang, K. S.; Chen, C. T.; Jeng, H. T.; Huang, S. W.; Yang, T. J.; Shen, C. C.; Liu, R. S.; Lin, J. Y.; Hu, Z.

2009-01-01

306

Effective valency of Dy ions in Dy3NatC80 metallofullerenes and peapods  

NASA Astrophysics Data System (ADS)

We report on the electronic properties of the trimetal-nitride fullerene Dy3NatC80 and its encapsulated form inside SWCNT, the metallofullerene peapod, using high-energy spectroscopic methods as probes. From a comparison of the Dy 4d-4f absorption edges and the valence-band photoemission spectra with atomic multiplet calculations the effective valency of the encapsulated rare-earth ions is evaluated. We observe that the Dy ions inside fullerene cage are essentially trivalent which is not affected by the peapod formation.

Shiozawa, H.; Rauf, H.; Pichler, T.; Knupfer, M.; Kalbac, M.; Yang, S.; Dunsch, L.; Bchner, B.; Batchelor, D.; Kataura, H.

2005-09-01

307

Magnetic properties of Dy sub 2 Fe sub 17 and Dy sub 2 Fe sub 17 C  

SciTech Connect

The magnetic properties of Dy{sub 2}Fe{sub 17} and Dy{sub 2}Fe{sub 17}C have been reported. The expansion of the lattice and increase of Curie temperature {ital T}{sub {ital c}} and magnetization {ital M} have been found for Dy{sub 2}Fe{sub 17}C, and compared with Dy{sub 2}Fe{sub 17}. From the study of {sup 57}Fe Mossbauer spectra, we found that the average hyperfine field of Dy{sub 2}Fe{sub 17}C is about 5 T larger than that of Dy{sub 2}Fe{sub 17}. The isomer shift of the 4{ital f} site is smaller for Dy{sub 2}Fe{sub 17}C compared with Dy{sub 2}Fe{sub 17}.

Tang, N.; Liang, J.Z.; Yu, M.; Lu, Y.; Tegus, O.; Li, Q.A.; Chen, G.M.; Liu, Y.L.; Yang, F. (Magnetism Laboratory, Institute of Physics, Academia Sinica, Beijing 100080 (China))

1991-11-15

308

Giant magnetoresistance in RENiSb semiconductors (RE=Tb,Dy,Ho)  

NASA Astrophysics Data System (ADS)

A giant magnetoresistance is observed at low temperatures in RENiSb semiconductors, and is studied as function of field and temperature. The magnetoresistance scales roughly with the square of the magnetization in the paramagnetic state, the proportionality factor depending on the amplitude of the resistivity itself and being higher for a low carrier density.

Pierre, J.; Karla, I.

2000-07-01

309

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

310

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

2012-07-23

311

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

Microsoft Academic Search

Laminin-2 is part of the basement membrane of the skeletal muscle fibers. The laminin ?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 heterogenous primary mouse muscle cell cultures conferred laminin ?2 chain expression in dy\\/dy mice muscles upon cell transplantation. In

J-T Vilquin; B Gurette; J Puymirat; D Yaffe; F M S Tom; M Fardeau; M Fiszman; K Schwartz; J P Tremblay

1999-01-01

312

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

313

Two-Dimensional Coordination Polymers Constructed by [Ni(II)Ln(III)] Nodes and [W(IV)(bpy)(CN)6](2-) Spacers: A Network of [Ni(II)Dy(III)] Single Molecule Magnets.  

PubMed

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

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

2013-09-25

314

Selecting cold 2n transfer in 162Dy(116Sn,118Sn)160Dy  

NASA Astrophysics Data System (ADS)

Cold 2n transfer has been studied using the reaction 162Dy(116Sn,118Sn)160Dy at energies in the vicinity of the Coulomb barrier. The experiment was performed at the Heidelberg-Darmstadt Crystal Ball spectrometer which was extended by 6 Compton suppressed Ge-detectors. It is demonstrated, that the direct population of intrinsically cold states in the deformed 160Dy transfer product can be selected by identifying and suppressing excitations to states above the yrast line using the Crystal Ball. The probability for populating yrast states in the deformed 160Dy nuclei in a 2n transfer reaction increases from 7% at grazing collisions up to ? 50% at large impact parameters, while the probability for populating the ground state in the spherical 2n transfer product 118Sn stays about constant at ? 45% for all measured impact parameters.

Hrtlein, T.; Bauer, H.; Pansegrau, D.; Schwalm, D.

1999-01-01

315

High spin states in 158 Dy  

NASA Astrophysics Data System (ADS)

High spin states in 158 Dy have been investigated using in-beam ? -ray spectroscopy techniques with the 150 Nd ( 12 C ,4n) reaction. Six rotational bands and several interband transitions have been observed. Sidebands have been discussed in terms of quasiparticle configurations.

Hayakawa, T.; Toh, Y.; Oshima, M.; Matsuda, M.; Hatsukawa, Y.; Shizuma, T.; Katakura, J.; Iimura, H.; Mitarai, S.; Zhang, Y. H.; Sugawara, M.; Kusakari, H.

2003-12-01

316

GD3 ganglioside and apoptosis  

Microsoft Academic Search

Lipid and glycolipid mediators are important messengers of the adaptive responses to stress, including apoptosis. In mammalian cells, the intracellular accumulation of ganglioside GD3, an acidic glycosphingolipid, contributes to mitochondrial damage, a crucial event during the apoptopic program. GD3 is a minor ganglioside in most normal tissues. Its expression increases during development and in pathological conditions such as cancer and

Florence Malisan; Roberto Testi

2002-01-01

317

The TB epidemic from 1992 to 2002  

Microsoft Academic Search

In 1992, less than 20 countries were implementing a sound TB control strategy. At the same time, TB was being resurrected as a major public health problem world-wide after two decades of neglect. Awareness of upward trends in the industrialized countries and MDR-TB outbreaks in large cities were driving forces behind the re-emergence of TB in the international health agenda.

Mario C. Raviglione

2003-01-01

318

Is TB in Your Curriculum?  

ERIC Educational Resources Information Center

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

Kerr, Joanne; Elwell, Jack

2002-01-01

319

Pulmonary impairment after tuberculosis and its contribution to TB burden  

Microsoft Academic Search

BACKGROUND: The health impacts of pulmonary impairment after tuberculosis (TB) treatment have not been included in assessments of TB burden. Therefore, previous global and national TB burden estimates do not reflect the full consequences of surviving TB. We assessed the burden of TB including pulmonary impairment after tuberculosis in Tarrant County, Texas using Disability-adjusted Life Years (DALYs). METHODS: TB burden

Jotam G Pasipanodya; Scott JN McNabb; Peter Hilsenrath; Sejong Bae; Kristine Lykens; Edgar Vecino; Guadalupe Munguia; Thaddeus L Miller; Gerry Drewyer; Stephen E Weis

2010-01-01

320

Heightened Vulnerability to MDR-TB Epidemics after Controlling Drug-Susceptible TB  

PubMed Central

Background Prior infection with one strain TB has been linked with diminished likelihood of re-infection by a new strain. This paper attempts to determine the role of declining prevalence of drug-susceptible TB in enabling future epidemics of MDR-TB. Methods A computer simulation of MDR-TB epidemics was developed using an agent-based model platform programmed in NetLogo (See http://mdr.tbtools.org/). Eighty-one scenarios were created, varying levels of treatment quality, diagnostic accuracy, microbial fitness cost, and the degree of immunogenicity elicited by drug-susceptible TB. Outcome measures were the number of independent MDR-TB cases per trial and the proportion of trials resulting in MDR-TB epidemics for a 500 year period after drug therapy for TB is introduced. Results MDR-TB epidemics propagated more extensively after TB prevalence had fallen. At a case detection rate of 75%, improving therapeutic compliance from 50% to 75% can reduce the probability of an epidemic from 45% to 15%. Paradoxically, improving the case-detection rate from 50% to 75% when compliance with DOT is constant at 75% increases the probability of MDR-TB epidemics from 3% to 45%. Conclusions The ability of MDR-TB to spread depends on the prevalence of drug-susceptible TB. Immunologic protection conferred by exposure to drug-susceptible TB can be a crucial factor that prevents MDR-TB epidemics when TB treatment is poor. Any single population that successfully reduces its burden of drug-susceptible TB will have reduced herd immunity to externally or internally introduced strains of MDR-TB and can experience heightened vulnerability to an epidemic. Since countries with good TB control may be more vulnerable, their self interest dictates greater promotion of case detection and DOTS implementation in countries with poor control to control their risk of MDR-TB.

Bishai, Jason D.; Bishai, William R.; Bishai, David M.

2010-01-01

321

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

NASA Astrophysics Data System (ADS)

The ternary rare-earth-metal chromium gallides RE4CrGa12 (RE=Tb-Tm) have been prepared by reactions of the elements at 1000 C in the presence of excess gallium used as a self-flux. Their structures are derived by inserting Cr atoms into a quarter of the empty Ga6 octahedral clusters found in the parent binary gallides REGa3 (AuCu3-type), although single-crystal X-ray diffraction studies suggest that complex superstructures may be adopted. An ideal ordered Y4PdGa12-type structure was successfully refined for a crystal of Dy4CrGa12 (Pearson symbol cI34, space group Im3m, Z=2, a=8.572(1) ). Magnetic measurements on single-crystal samples reveal ferromagnetic or possibly ferrimagnetic ordering for the Tb, Dy, and Er members (TC=22, 15, and 2.8 K, respectively) and antiferromagnetic ordering for the Ho member (TN=7.5 K). Band structure calculations on a hypothetical Y4CrGa12 model suggest that the Cr atoms carry no local magnetic moment.

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

2012-12-01

322

Recent Advances in Testing for Latent TB  

PubMed Central

After more than a century of relying on skin testing for the diagnosis of latent TB infection, clinicians now have access to blood-based diagnostics in the form of interferon ? release assays (IGRAs). These tests are generally associated with higher sensitivity and specificity for diagnosis of latent TB infection. This article reviews the indications for testing and treatment of latent TB infection in the overall context of a TB control program and describes how IGRAs might be used in specific clinical settings and populations, including people having close contact with an active case of TB, the foreign born, and health-care workers.

Burzynski, Joseph

2010-01-01

323

Recent advances in testing for latent TB.  

PubMed

After more than a century of relying on skin testing for the diagnosis of latent TB infection, clinicians now have access to blood-based diagnostics in the form of interferon ? release assays (IGRAs). These tests are generally associated with higher sensitivity and specificity for diagnosis of latent TB infection. This article reviews the indications for testing and treatment of latent TB infection in the overall context of a TB control program and describes how IGRAs might be used in specific clinical settings and populations, including people having close contact with an active case of TB, the foreign born, and health-care workers. PMID:21138881

Schluger, Neil W; Burzynski, Joseph

2010-12-01

324

Quadrupole moments and identical superdeformed bands in {sup 149}Tb  

SciTech Connect

Five superdeformed (SD) bands have been observed in {sup 149}Tb, using the Gammasphere spectrometer. The measurement was performed with a backed target to obtain lifetime information from a Doppler-shift attenuation method analysis. It is proposed that the yrast SD band corresponds to the {sup 148}Gd(yrast){circle_times}{pi}6{sup 3} intruder configuration. The first excited band (band 2) is found to be identical to the {sup 150}Tb yrast SD band. Band 3 is proposed to correspond to the {pi}[301]1/2({alpha}={minus}1/2){r_arrow}[651]3/2({alpha}={minus}1/2) proton-hole excitation coupled to the {pi}6{sup 4}{nu}7{sup 1}({nu}[651]1/2){sup {minus}1} intruder configuration. Bands 4 and 5, the weakest SD bands seen in the present work, show similarities with band 3 and are most likely associated with a similar intruder configuration. {copyright} {ital 1998} {ital The American Physical Society}

Kharraja, B.; Garg, U.; Jin, H.; Ernst, R.J.; Ghugre, S.S. [Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Janssens, R.V.; Carpenter, M.P.; Fischer, S.M.; Khoo, T.L.; Lauritsen, T.; Nisius, D. [Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Moore, E.F. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States); Byrski, T. [I.Re.S, IN2P3, Universite Louis Pasteur, Strasbourg 67037 (France); Kruecken, R.; Macchiavelli, A.O.; MacLeod, R. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, Califonia 94720 (United States); Kaczarowski, R. [Soltan Institute for Nuclear Studies, 05-400 Swierk (Poland); Govil, I.M. [Department of Physics, Panjab University, Chandigarh 160 014 (India)

1998-09-01

325

Enhancement of malignant properties of human osteosarcoma cells with disialyl gangliosides GD2/GD3.  

PubMed

The expression and implications of gangliosides in human osteosarcomas have not been systematically analyzed. In this study, we showed that gangliosides GD3 and GD2 are highly expressed in the majority of human osteosarcoma cell lines derived from oral cavity regions. Introduction of GD3 synthase cDNA into a GD3/GD2-negative (GD3/GD2-) human osteosarcoma subline resulted in the establishment of GD3/GD2+ transfectant cells. They showed increased cell migration and invasion activities in wound healing and Boyden chamber invasion assays, respectively, compared to the control cells. When treated with serum, GD3/GD2+ cells showed stronger tyrosine phosphorylation of p130Cas, focal adhesion kinase, and paxillin than GD3/GD2- cells. In particular, paxillin underwent much stronger phosphorylation, suggesting its role in cell motility. Furthermore, we tried to dissect the roles of GD3 and GD2 in the malignant properties of the transfectant cells by establishing single ganglioside-expressing cells, that is, either GD3 or GD2. Although GD3/GD2+ cells showed the most malignant properties, GD2+ cells showed almost equivalent levels to GD3/GD2+ cells in invasion and migration activities, and in the intensities of tyrosine phosphorylation of paxillin. Among Src family kinases, Lyn was expressed predominantly, and was involved in the invasion and motility of GD3- and/or GD2-expressing transfectants. Furthermore, it was elucidated by gene silencing that Lyn was located in a different pathway from that of FAK to eventually lead paxillin activation. These results suggested that GD2/GD3 are responsible for the enhancement of the malignant features of osteosarcomas, and might be candidate targets in molecular-targeted therapy. PMID:22632091

Shibuya, Hidenobu; Hamamura, Kazunori; Hotta, Hiroshi; Matsumoto, Yasuyuki; Nishida, Yoshihiro; Hattori, Hisashi; Furukawa, Keiko; Ueda, Minoru; Furukawa, Koichi

2012-07-16

326

Optical response of DyN  

NASA Astrophysics Data System (ADS)

We report measurements of the optical response of polycrystalline DyN thin films. The frequency-dependent complex refractive index in the near IR-visible-near UV was determined by fitting reflection/transmission spectra. In conjunction with resistivity measurements, these identify DyN as a semiconductor with an optical energy gap of 1.2 eV. When doped with nitrogen vacancies it shows free carrier absorption and a blue-shifted gap associated with the Moss-Burstein effect. The refractive index of 2.0 +/- 0.1 depends only weakly on energy. Far infrared reflectivity data show a polar phonon of frequency 280 cm-1 and a dielectric strength of ??=20.

Azeem, M.; Ruck, B. J.; Do Le, Binh; Warring, H.; Trodahl, H. J.; Strickland, N. M.; Koo, A.; Goian, V.; Kamba, S.

2013-05-01

327

Extreme ultraviolet spectra from N-shell ions of Gd, Dy and W  

NASA Astrophysics Data System (ADS)

Measurements of extreme ultraviolet radiation from gadolinium, dysprosium and tungsten ions with an open n = 4 shell were performed at the National Institute of Standards and Technology. The ions were produced and confined in an electron beam ion trap, and the spectra were recorded with a flat-field grazing-incidence spectrometer in the wavelength range 3.5-17.5 nm. These data are useful for the development of future lithography sources and for diagnostics of hot plasmas in fusion devices.

Kilbane, D.; Gillaspy, J. D.; Ralchenko, Yu; Reader, J.; O'Sullivan, G.

2013-09-01

328

TB vaccines: progress and problems  

Microsoft Academic Search

Tuberculosis (TB) is the biggest killer worldwide of any infectious disease, a situation worsened by the advent of the HIV epidemic and the emergence of multi-drug resistant strains of Mycobacterium tuberculosis. The existing vaccine, Mycobacterium bovis bacille CalmetteGurin (BCG), has proven inefficient in several recent field trials. There is currently intense research using cutting-edge vaccine technology to combat this ancient

Peter Andersen

2001-01-01

329

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

PubMed

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

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

2003-04-14

330

Octupole Vibration in Superdeformed 15266Dy86  

Microsoft Academic Search

Nine transitions of dipole character have been identified linking an excited superdeformed (SD) band in 152Dy to the yrast SD band. As a result, the excitation energy of the lowest level in the excited SD band has been measured to be 14 238keV. This corresponds to a 1.3MeV excitation above the SD ground state. The levels in this band have

T. Lauritsen; R. V. Janssens; M. P. Carpenter; P. Fallon; B. Herskind; D. G. Jenkins; T. L. Khoo; F. G. Kondev; A. Lopez-Martens; A. O. Macchiavelli; D. Ward; K. Abu Saleem; I. Ahmad; R. M. Clark; M. Cromaz; T. Dssing; A. M. Heinz; A. Korichi; C. J. Lister; D. Seweryniak

2002-01-01

331

Thermoluminescence of SrSO4:Dy and BaSO4:Dy (dosimetric properties)  

Microsoft Academic Search

The thermoluminescence of SrSO4 and BaSO4 doped with dysprosium and thulium was studied. The phosphors were crystallized from H2SO4 solution by evaporation. SrSO4:Dy and SrSO4:Tm exhibit the same glow curve, both having a major glow peak at 140 degrees C. BaSO4:Dy and BaSO4:Tm also exhibit identical glow peaks at 130 degrees C which are similar to the SrSO4 peaks except

R L Dixon; K E Ekstrand

1974-01-01

332

Thermal neutron cross-section and resonance integral for 164Dy(n,gamma)165Dy reaction  

Microsoft Academic Search

The thermal neutron cross-section (sigma0) and the resonance integral (I0) of the reaction 164Dy(n,gamma)165Dy were measured by the activation method, using 55Mn(n,gamma)55Mn monitor reaction as a single comparator. The diluted MnO2 and Dy2O3 powder samples within and without a cylindrical Cd shield case were irradiated in an isotropic neutron field obtained from the 241Am Be neutron sources, moderated with paraffin

Mustafa Karadag; Haluk Ycel

2005-01-01

333

Synthesis of monodisperse sub-3 nm RE2O3 and Gd2O3:RE3+ nanocrystals  

Microsoft Academic Search

Monodisperse, colloidally stable, sub-3 nm europium sesquioxide (Eu2O3), terbium sesquioxide (Tb2O3), and Eu3+-doped gadolinium sesquioxide (Gd2O3:Eu3+) nanocrystals have been synthesized via a hot solution-phase technique. The oleic acid concentration facilitated the production of the nanocrystals in a range of sizes from sub-2 nm up to 5.0 nm. The Eu2O3 and Gd2O3:Eu3+ nanocrystals exhibit new luminescence peaks at 620 nm, which

S. V. Mahajan; J. H. Dickerson

2007-01-01

334

155,157 Gd NMR study of GdNi intermetallic compounds  

Microsoft Academic Search

The spin-echo NMR technique was used to study the magnetic properties of the following intermetallic compounds of the GdNi series: Gd2Ni17, GdNi5, GdNi3, GdNi2 and GdNi, with 155Gd and 157Gd nuclei as local probes. These compounds have different crystal structures and order ferri- or ferromagnetically. The NMR measurements were performed at 4.2 and 1.5K. The NMR spectra were compared to

V. L. B de Jesus; I. S Oliveira; P. C Riedi; A. P Guimares

2000-01-01

335

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

336

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

Microsoft Academic Search

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

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

2003-01-01

337

Phthalocyanine-dyed fibers adsorb allergenic proteins.  

PubMed

Phthalocyanine (Pc)-dyed fiber is reported to reduce atopic symptoms in some patients when they use underwear made of the fiber. We investigated the adsorption of allergens on Pc-fiber. Pc-fiber trapped house dust/pollen/food allergens with varied molecular weight and pI. The adsorbed allergens were released in the presence of mild detergent. Pc-fiber did not change the molecular weight or disulfide bonding of the allergens. These observations imply that Pc-fiber is applicable as an "allergen trap" for a wide variety of products. PMID:16583306

Yano, H; Sugihara, Y; Shirai, H; Wagatsuma, Y; Kusada, O; Matsuda, T; Kuroda, S; Higaki, S

2006-04-04

338

Dy3+-doped zinc fluorophosphate glasses for white luminescence applications  

NASA Astrophysics Data System (ADS)

Dysprosium (Dy3+) ions doped zinc fluorophosphate (PKAZLFDy: P2O5-K2O-Al2O3-ZnF2-LiF-Dy2O3) glasses have been prepared and investigated their spectroscopic properties using absorption, emission and decay measurements. Judd-Ofelt analysis has been carried out to obtain the intensity parameters and in turn predicted radiative properties for the 4F9/2 level of 1.0 mol% of Dy2O3 doped glass. Visible luminescence spectra have been obtained due to 4F9/2 ? 6HJ (J = 11/2, 13/2, 15/2) transitions of Dy3+ ions under 385 nm excitation. The yellow-to-blue luminescence intensity ratios and chromaticity coordinates of Dy3+ ions in these glasses have been analyzed as a function of Dy3+ ion concentration. The decay profiles for the 4F9/2 level exhibit perfectly single exponential at lower concentrations (up to 1.0 mol%) and turn into non-exponential for higher concentrations (>1.0 mol%) due to energy transfer between donor (excited state Dy3+ ion) and acceptor (ground state Dy3+ ion). The results reveal that these glasses emit bright white light which is suitable for the development of W-LEDs.

Vijaya, N.; Upendra Kumar, K.; Jayasankar, C. K.

2013-09-01

339

Oxide Dispersion-Strengthened Ferritic Alloys. Dy Data Sheet.  

National Technical Information Service (NTIS)

This publication gives the available data on the DY dispersion-strengthened ferritic alloys developed at C.E.N./S.C.K. Mol, Belgium. DY is a Fe-Cr-Mo ferritic alloy, strengthened by addition of yttrium oxide and of titanium leading to the formation of Chi...

P. van Asbroeck

1976-01-01

340

Luminescence quenching of Dy3+ ions in lead bismuthate glasses  

NASA Astrophysics Data System (ADS)

Luminescence of lead bismuthate glasses PbO-Bi2O3-Ga2O3 containing Dy3+ ions has been studied. Two overlapping luminescence bands corresponding to 3P1-1S0 transition of Bi3+ and 4F9/2 - 6H13/2 transition of Dy3+ were detected under 480 nm excitation. Comparison of luminescence features for the system under study to those reported for dysprosium-doped lead borate glass PbO-B2O3-Ga2O3 indicates that the luminescence of Dy3+ is efficiently quenched by Bi3+ ions. Analysis of luminescence dynamics implies that the excitation energy transfer from Dy3+ to Bi3+ is nonradiative. The theoretical calculations using Inokuti-Hirayama model confirm strong luminescence of Dy3+ ions in lead bismuthate glasses.

Pisarski, Wojciech A.; Pisarska, Joanna; Lisiecki, Rados?aw; Dominiak-Dzik, Gra?yna; Ryba-Romanowski, Witold

2012-04-01

341

Pitfalls of TB management in prisons, revisited  

Microsoft Academic Search

Almost 10 years ago, attention was drawn to the many pitfalls involved in the treatment of tuberculosis (TB) in prison settings, based on field experience from the ICRC (International Committee of the Red Cross) (Coninx et al., 1995). Since that time, the ICRC has continued working in the field of TB in prisons, either directly, or by supporting the local

Hernn Reyes

2007-01-01

342

Magnetism and magnetocaloric effect in (DyxGd5-x)Si2Ge2 (0<=x<=5) compounds  

NASA Astrophysics Data System (ADS)

Temperature and field dependence of magnetization of Dy-substituted Gd5Si2Ge2 compounds has been studied in the temperature range of 5-330 K. The (DyxGd5-x)Si2Ge2 compounds with x=0.5, 1.5, 3.0, and 3.5 are found to order ferromagnetically with magnetic ordering temperature TC ranging between ~270 and 80 K. The Dy substitution in Gd5Si2Ge2 leads to a lowering of TC, an increase in coercivity, and also to a loss of the first order magnetic phase transition seen in the parent compound. The magnetic entropy change ?SM associated with the magnetic transition has been computed using the magnetization-field isotherm data. The maximum magnetic entropy changes of ~8.8, 13.9, and 6.9 J/kg K are obtained for x=0.5, 3.0, and 5 compounds, respectively, for a field change of 55 kOe. The ?SM is spread around TC over a few tens of Kelvin and this feature makes these materials promising for possible use in Ericsson-cycle magnetic refrigerator applications.

Nirmala, R.; Kundaliya, Darshan C.; Shinde, S. R.; Joshi, Amish G.; Morozkin, A. V.; Malik, S. K.

2007-06-01

343

Rotational bands of 155Gd  

NASA Astrophysics Data System (ADS)

High spin states of 155Gd have been investigated using the 150Nd(12C, ?3n) reaction. Three rotational bands have been observed. Two of them have been extended up to (51/2)+ and 45/2-, respectively, and another band has been newly observed. The backbending and blocking effects are discussed in comparison with the calculation of cranked shell model. The routhians and the B(M1)/B(E2) ratio of the high-? rotational band are compared with the calculation by the tilted axis cranking model. In addition the ground state rotational band of 156Gd has been extended up to 22+.

Hayakawa, T.; Oshima, M.; Hatsukawa, Y.; Katakura, J.; Iimura, H.; Matsuda, M.; Mitarai, S.; Shimizu, Y. R.; Ohtsubo, S.-I.; Shizuma, T.; Sugawara, M.; Kusakari, H.

1999-09-01

344

Magnetoresistance in nanostructured Tb/Ti and Tb/Si multilayers  

SciTech Connect

Magnetic, magnetoresistive and structural properties were studied for [Tb/Ti]{sub n} and [Tb/Si]{sub n} multilayers which were prepared by rf-sputtering. The thickness of the Tb layers varied from 1.5 to 12 nm. The thickness of 2 nm nonmagnetic spacers of Ti or Si was kept constant. Both anisotropic and isotropic magnetoresistance was observed in [Tb/Ti]{sub n} and [Tb/Si]{sub n} multilayers. A decrease in the thickness of the terbium layers led to a decrease in the anisotropic contribution to the total magnetoresistance. The negative isotropic magnetoresistanse in [Tb/Ti]{sub n} and [Tb/Si]{sub n} multilayers can be attributed to the giant magnetoresistance (GMR) and/or high field isotropic magnetoresistance. The structure of the samples of both types enabled the existence of the GMR effect.

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

2011-01-15

345

HIV-TB: the 'cursed duet'.  

PubMed

Tuberculosis is the most common infection among HIV-infected patients in India. More deaths were reported due to tuberculosis in AIDS patients in pre-antiretroviral therapy era. HIV is the strongest of all known, risk factors for the development of TB. Tuberculosis can develop at any stage of the HIV disease. Extrapulmonary tuberculosis is more common and constitues half of the cases in HIV-infected individual with TB. Hilar lymphadenopathy is frequently observed. TB in HIV frequently poses a diagnostic challenge. Acid-fast bacillus demonstration on sputum smear microscopy is the main-stay laboratory investigation for TB. In addition to antituberculous therapy, antiretroviral therapy must be initiated in HIV-infected individual with TB. Early referrals to the RNTCP and ART programmes are the best option for management. PMID:21888159

Kumar, Amitabh; Agarwal, Upasna

2011-01-01

346

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

347

Magnetic Ordering in Ba2DyRuO6  

NASA Astrophysics Data System (ADS)

Magnetization measurements and neutron diffraction (ND) studies have been carried out on the double perovskite ruthenate, Ba2DyRuO6. The low field magnetization data indicate ordering around 50K, a sharp rise below 8K and a possible transition around 25K. Rietveld analysis of ND data confirms antiferromagnetic ordering at 48K. The temperature dependence of the Ru moment appears to follow a Brillouin type curve down to the lowest temperature accessible, (12K), and there is no evidence for a transition around 25K. In contrast, the Dy moment is found to be proportional to the square of the Ru moment, implying that the Ru moment is the primary order parameter and that Dy ordering is driven by the Ru-Dy coupling. The ND experiment could not reach the temperature at which the magnetization rises sharply (8K), but following similar arguments, we suggest that this point represents the temperature at which the Dy-Dy interactions become larger than the Ru-Dy interactions, and may, thus, lead to a new structure.

Lamsal, J.; Yelon, W.; Blackstead, H.; Smylie, M.; Cai, Q.; James, W.; Yang, J.

2009-03-01

348

Growth of DySi2 Nanowires on Si(001)  

NASA Astrophysics Data System (ADS)

Deposition of Dy on Si(001) at 600^oC leads to the formation of silicide DySi2 nanowires on a 24 reconstructed surface with DySi2 (01\\overline10)//Si(001) and the long dimension (DySi_2[11\\overline20]) perpendicular to the Si dimer row direction (Si[1\\overline10]). STM was used to characterize the surface. Typical lengths of nanowires are hundreds of nanometers, and widths are between 4 a and 12 a, where a=0.384 nm is the lattice parameter of the Si surface. The reason for the formation of nanowires is that the silicide matches the Si(001) surface very well in one direction (along the length of the wire) but has a significant mismatch in the perpendicular direction, which limits the maximum width of the nanowire. The height of the nanowires is quantized with a height quantum of 0.33 nm, which corresponds to the DySi2 unit cell dimension along the [1\\overline100] direction. The Dy atoms on the 24 reconstructed surface sit in positions similar to those of Dy atoms in the silicide.

Liu, Bangzhi; Nogami, Jun

2001-03-01

349

?-decay half-lives of new neutron-rich rare-earth isotopes 159Pm,162Sm, and 166Gd  

NASA Astrophysics Data System (ADS)

The new neutron-rich rare-earth isotopes 159Pm, 162Sm, and 166Gd produced in the proton-induced fission of 238U were identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport system. The half-lives of 159Pm, 162Sm, and 166Gd were determined to be 1.5 0.2, 2.4 0.5, and 4.8 1.0 s respectively. The partial decay scheme of 166Gd was constructed from ??-coincidence data. A more accurate half-life value of 25.6 2.2 s was obtained for the previously identified isotope 166Tb. The half-lives measured in the present study are in good agreement with the theoretical predictions calculated by the second generation of the gross theory with the atomic masses evaluated by Audi and Wapstra.

Ichikawa, S.; Asai, M.; Tsukada, K.; Haba, H.; Nagame, Y.; Shibata, M.; Sakama, M.; Kojima, Y.

2005-06-01

350

Magnetic structure of GdNiSn  

NASA Astrophysics Data System (ADS)

The magnetic structure of the TiNiSi-type GdNiSn compound has been studied by both 155Gd Mssbauer spectrocopy and neutron powder diffraction. The results suggest a square-wave modulated magnetic structure characterized by the propagation vector k = [0.426, 0.351, 0] and Gd magnetic moments of 6.52(15)?B (at 3.6 K) oriented along the c-axis. The results are compared with those of the isotypic RNiSn compounds and with the possible magnetic structures of GdNiSn proposed from earlier 155Gd Mssbauer work.

Lee-Hone, N. R.; Lemoine, P.; Ryan, D. H.; Vernire, A.; Malaman, B.

2013-05-01

351

Forensic analysis of dyed textile fibers.  

PubMed

Textile fibers are a key form of trace evidence, and the ability to reliably associate or discriminate them is crucial for forensic scientists worldwide. While microscopic and instrumental analysis can be used to determine the composition of the fiber itself, additional specificity is gained by examining fiber color. This is particularly important when the bulk composition of the fiber is relatively uninformative, as it is with cotton, wool, or other natural fibers. Such analyses pose several problems, including extremely small sample sizes, the desire for nondestructive techniques, and the vast complexity of modern dye compositions. This review will focus on more recent methods for comparing fiber color by using chromatography, spectroscopy, and mass spectrometry. The increasing use of multivariate statistics and other data analysis techniques for the differentiation of spectra from dyed fibers will also be discussed. PMID:19543886

Goodpaster, John V; Liszewski, Elisa A

2009-06-20

352

New rare earth metal-rich indides RE14Ni3In3 (RE=Sc, Y, Gd Tm, Lu)synthesis and crystal chemistry  

NASA Astrophysics Data System (ADS)

The rare earth nickel indides RE14Ni3In3 (RE=Sc, Y, Gd Tm, Lu) were synthesized from the elements by arc-melting and subsequent annealing. The compounds were investigated on the basis of X-ray powder and single crystal data: Lu14Co2In3 type, P42/nmc, Z=4, a=888.1(1), c=2134.7(4), wR2=0.0653, 1381 F2 values, 63 variables for Sc13.89Ni3.66In2.45; a=961.2(1), c=2316.2(5), wR2=0.0633, 1741 F2 values, 64 variables for Y13.84Ni3.19In2.97; a=965.3(1), c=2330.5(5), wR2=0.0620, 1765 F2 values, 63 variables for Gd14Ni3.29In2.71; a=956.8(1), c=2298.4(5), wR2=0.0829, 1707 F2 values, 64 variables for Tb13.82Ni3.36In2.82; a=951.7(1), c=2289.0(5), wR2=0.0838, 1794 F2 values, 64 variables for Dy13.60Ni3.34In3.06; a=948.53(7), c=2270.6(1), wR2=0.1137, 1191 F2 values, 64 variables for Ho13.35Ni3.17In3.48; a=943.5(1), c=2269.1(5), wR2=0.0552, 1646 F2 values, 64 variables for Er13.53Ni3.14In3.33; a=938.42(7), c=2250.8(1), wR2=0.1051, 1611 F2 values, 64 variables for Tm13.47Ni3.28In3.25; a=937.3(1), c=2249.6(5), wR2=0.0692, 1604 F2 values, 64 variables for Tm13.80Ni3.49In2.71; and a=933.4(1), c=2263.0(5), wR2=0.0709, 1603 F2 values, 64 variables for Lu13.94Ni3.07In2.99. The RE14Ni3In3 indides show significant Ni/In mixing on the 4c In1 site. Except the gadolinium compound, the RE14Ni3In3 intermetallics also reveal RE/In mixing on the 4c RE1 site, leading to the refined compositions. Due to the high rare earth metal content, the seven crystallographically independent RE sites have between 9 and 10 nearest RE neighbors. The RE14Ni3In3 structures can be described as a complex intergrowth of rare earth-based polyhedra. Both nickel sites have a distorted trigonal-prismatic rare earth coordination. An interesting feature is the In2 In2 dumb-bell at an In2 In2 distance of 304 pm (for Gd14Ni3.29In2.71). The crystal chemical peculiarities of the RE14Ni3In3 indides are briefly discussed.

Lukachuk, Mar'Yana; Galadzhun, Yaroslav V.; Zaremba, Roman I.; Dzevenko, Mariya V.; Kalychak, Yaroslav M.; Zaremba, Vasyl I.; Rodewald, Ute Ch.; Pttgen, Rainer

2005-09-01

353

A study of electrode temperature lowering in Dy-containing ceramic metal halide lamps: I. The effect of mixtures of Dy, Tl and Na compared with pure Dy  

NASA Astrophysics Data System (ADS)

The reduction in the electrode temperature by the gas phase emitter effect of dysprosium in ceramic metal halide lamps is investigated within special research lamps in dependence on the operating frequency of switched-dc lamp currents. The lamp tubes are made of transparent YAG material. They are filled with a fixed amount of Hg, which produces a buffer gas during lamp operation at a pressure of 2 MPa, with different amounts of DyI3 and in part with different amounts of NaI plus TlI. The Dy atomic ground state density is measured phase resolved both in the middle of the discharge and in front of the upper electrode by broad band absorption spectroscopy. The Dy ion density in front of the electrode is evaluated from line intensities being measured in absolute units by emission spectroscopy. The electrode tip temperature is determined by a 1? - 2D pyrometric measuring method. It is found that a high Dy ion density in front of the electrode is correlated with a strong reduction in the electrode tip temperature relating to a pure mercury lamp. At low operating frequencies (f ? 100 Hz) the Dy ion density and the temperature reduction is high within the cathodic phase and low within the anodic phase, at higher operating frequencies an increased Dy ion density and a reduction in the electrode tip temperature overlaps onto the anodic phase. The Dy ion density is reduced and with it the tip temperature drop by an addition of Na and Tl vapour to the lamp plasma. The effect of Tl and Na is investigated in more detail in a successive paper.

Westermeier, M.; Ruhrmann, C.; Bergner, A.; Denissen, C.; Suijker, J.; Awakowicz, P.; Mentel, J.

2013-05-01

354

Magnetic properties of Fe/Tb multilayers  

SciTech Connect

Multilayered Fe/Tb samples were prepared under ultrahigh vacuum conditions ({ital p}{lt}10{sup {minus}9} mbar) on kapton substrates. A total of four different samples were prepared. Three of them correspond to a series where the Tb thickness is constant at 26 A and Fe varies from 10 to 30 A. The fourth one is the first of a new series where Tb is 7 A thick and Fe 40 A. The samples were investigated by means of SQUID magnetometry and Moessbauer spectroscopy. All samples show perpendicular magnetic anisotropy at low temperature (4.2 K), but only two of them are able to show it at room temperature.

Badia, F.; Badry, M.A.; Zhang, X.X.; Tejada, J. (Dep. Fisica Fonamental, Universitat de Barcelona, Diagonal, 647, E-08028 Barcelona (Spain)); Brand, R.A.; Scholz, B.; Keune, W. (Laboratorium fuer Angewandte Physik, 4100 Duisburg (Germany))

1991-11-15

355

Comparison of GD2 binding capture ELISA assays for anti-GD2-antibodies using GD2-coated plates and a GD2-expressing cell-based ELISA.  

PubMed

Two assay methods for quantification of the disialoganglioside (GD2)-specific binding activities of anti-GD2 monoclonal antibodies and antibody immunofusion proteins, such as ch14.18 and hu14.18-IL2, were developed. The methods differed in the use of either microtiter plates coated with purified GD2 or plates seeded with GD2-expressing cell lines to bind the anti-GD2 molecules. The bound antibodies were subsequently detected using the reactivity of the antibodies to an HRP-labeled anti-IgG Fc or antibodies recognizing the conjugate IL-2 part of the Hu 14.18IL-2 fusion protein. The bound HRP was detected using reagents such as orthophenylene diamine, 2, 2'-azinobis [3-ethylbenzothiazoline-6-sulfonic acid] or tetramethylbenzidine. The capture ELISA using GD2-coated plates was developed earlier in assay development and used to demonstrate assay specificity and to compare lot-to-lot consistency and stability of ch14.18, and Hu14.18 IL-2 in clinical development. During this study, we found a number of issues related to plate-to-plate variability, GD2 lot variability, and variations due to GD2 storage stability, etc., that frequently lead to assay failure in plates coated with purified GD2. The cell-based ELISA (CbELISA) using the GD2 expressing melanoma cell line, M21/P6, was developed as an alternative to the GD2-coated plate ELISA. The results on the comparability of the capture ELISA on GD2-coated plates and the cell-based assay show that both assays give comparable results. However, the cell-based assay is more consistent and reproducible. Subsequently, the anti-GD2 capture ELISA using the GD2-coated plate was replaced with the CbELISA for product lot release testing and stability assessment. PMID:21893062

Soman, Gopalan; Yang, Xiaoyi; Jiang, Hengguang; Giardina, Steve; Mitra, Gautam

2011-08-26

356

Encapsulation of radioactive [sup 159]Gd and [sup 161]Tb atoms in fullerene cages  

SciTech Connect

We demonstrate a novel form of metallofullerenes, namely, those with radioactive atoms encapsulated in the C[sub 82]cage. The metal atoms were made radioactive by a neutron capture reaction or through a nuclear decay process. The most important and intriguing finding of the present study is that the endohedral form of metallofullerenes is not affected by the recoil energy of the metal atom resulting from emission of electrons in the [beta] decay. Such a stability of the cage against the recoil energy of the encapsulated atom was confirmed by the elution behavior of the metallofullerene in liquid chromatography. Successful encapsulation of radioactive atoms inside the fullerene cage will greatly widen the potential use of endohedral metallofullerenes not only in basic science and technology but also in other areas, such as medicine. 14 refs., 3 figs.

Kikuchi, Koichi; Kobayashi, Kanako; Sueki, Keisuke; Suzuki, Shinzo; Nakahara, Hiromichi; Achiba, Yohji; Katada, Motomi (Tokyo Metropolitan Univ. (Japan)); Tomura, Kenji (Rikkyo Univ., Kanagawa (Japan))

1994-10-19

357

Magnetic, thermodynamic and transport properties of GdFe2(AlxZn1-x)20  

NASA Astrophysics Data System (ADS)

The unusual physical properties of the dilute, rare-earth-bearing, intermetallic compound GdFe2Zn20 have been explained as being the result of the Gd^3+ moment being embedded in a nearly ferromagnetic Fermi liquid. To understand this in detail, single crystals of the pseudo ternary series GdFe2(AlxZn1-x)20(x <=0.07) and YFe2(AlxZn1-x)20^ (x <=0.05) were grown out of Zn-rich solution. Magnetization, heat capacity and resistivity measurements on these compounds reveal a decrease of Tc from 86 K (x = 0) to 4 K (x = 0.07) for GdFe2(AlxZn1-x)20 and a decrease of the Stoner enhancement factor, Z, from 0.88 (x = 0) to 0.35 (x = 0.05) for YFe2(AlxZn1-x)20. Rigid band approximation and TB-LMTO-ASA calculation are used to explain this trend. These results, combined with earlier studies of the substitution of Co for Fe clearly indicate the importance of band filling and the applicability of even a simple rigid band model, to these compounds.

Lampe, M.; Ni, N.; Jia, S.; Samolyuk, G. D.; Sefat, A. S.; Bud'Ko, S. L.; Canfield, P. C.

2008-03-01

358

Host markers in Quantiferon supernatants differentiate active TB from latent TB infection: preliminary report  

PubMed Central

Background Interferon gamma release assays, including the QuantiFERON TB Gold In Tube (QFT) have been shown to be accurate in diagnosing Mycobacterium tuberculosis infection. These assays however, do not discriminate between latent TB infection (LTBI) and active TB disease. Methods We recruited twenty-three pulmonary TB patients and 34 household contacts from Cape Town, South Africa and performed the QFT test. To investigate the ability of new host markers to differentiate between LTBI and active TB, levels of 29 biomarkers in QFT supernatants were evaluated using a Luminex multiplex cytokine assay. Results Eight out of 29 biomarkers distinguished active TB from LTBI in a pilot study. Baseline levels of epidermal growth factor (EGF) soluble CD40 ligand (sCD40L), antigen stimulated levels of EGF, and the background corrected antigen stimulated levels of EGF and macrophage inflammatory protein (MIP)-1? were the most informative single markers for differentiation between TB disease and LTBI, with AUCs of 0.88, 0.84, 0.87, 0.90 and 0.79 respectively. The combination of EGF and MIP-1? predicted 96% of active TB cases and 92% of LTBIs. Combinations between EGF, sCD40L, VEGF, TGF-? and IL-1? also showed potential to differentiate between TB infection states. EGF, VEGF, TGF-? and sCD40L levels were higher in TB patients. Conclusion These preliminary data suggest that active TB may be accurately differentiated from LTBI utilizing adaptations of the commercial QFT test that includes measurement of EGF, sCD40L, MIP-1?, VEGF, TGF-? or IL-1? in supernatants from QFT assays. This approach holds promise for development as a rapid diagnostic test for active TB.

Chegou, Novel N; Black, Gillian F; Kidd, Martin; van Helden, Paul D; Walzl, Gerhard

2009-01-01

359

Community tuberculosis care through TB clubs in rural North Ethiopia  

Microsoft Academic Search

Non-compliance is a major problem in the treatment of tuberculosis (TB). This paper assesses the effectiveness of TB clubs in improving compliance with TB treatment and their impact in improving societal attitudes associated with TB. The study utilised both quantitative (cohort study) and qualitative (focus group discussion and an in-depth interview) methods. The cohort study was conducted in two rural

M. Demissie; H. Getahun; B. Lindtjrn

2003-01-01

360

Web-based Tools Help Fight TB in Taiwan  

Microsoft Academic Search

Background: Among communicable diseases, tuberculosis (TB) is a leading cause of death worldwide, killing 2 million people each year. TB in Taiwan is a major public health issue as well. In 2004, the mortality and incidence rates of TB in Taiwan were 4.2 and 74per 100000 population, respectively. Compared to the TB mortality and incidence rates in the United States

Jen-Hsiang Chuang; Shang-Lin Yang; Chan-Hsien Chiu; Hsu-Sung Kuo

361

Immunomodulation by vitamin D: implications for TB  

PubMed Central

TB remains a major cause of mortality throughout the world. Low vitamin D status has been linked to increased risk of TB and other immune disorders. These observations suggest a role for vitamin D as a modulator of normal human immune function. This article will detail the cellular and molecular mechanisms by which vitamin D regulates the immune system and how vitamin D insufficiency may lead to immune dysregulation. The importance of vitamin D bioavailability as a mechanism for defining the immunomodulatory actions of vitamin D and its impact on TB will also be discussed. The overall aim will be to provide a fresh perspective on the potential benefits of vitamin D supplementation in the prevention and treatment of TB.

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

2011-01-01

362

TB/HIV Facts 2011-2012  

MedlinePLUS

... 9789241503006/en/index.html ? In 2011 WHO issued technical and practical how to considerations for r apid ... in Response to TB/HIV WHO BUILDS CAPACITYthrough technical assistance and support to national initiatives to expand ...

363

Mssbauer spectra of Eu(III) and Gd(III) complexes of phosphine oxides with chelating perchlorate  

NASA Astrophysics Data System (ADS)

The reaction of Ln(ClO4)3 nH2O with triphenylphosphine oxide (TPPO) in methanol has led to the formation of [Ln(ClO4)2(tppo)4]ClO4MeOH (Ln = Nd, Eu, Gd, Dy, Yb), in which the perchlorate anion acts as a symmetric bidentate. The emission spectra of Eu(III)-TPPO complexes, showing enhancement in the intensity due to the phenyl group, indicate an isotropic electron distribution for the nitrato complex [Eu(NO3)3(tppo)2(EtOH)]. 151Eu and 155Gd Mssbauer spectra of the TPPO complexes also lead to the same conclusion.

Takahashi, Masashi; Hirai, Yuya

2012-03-01

364

The global situation of MDR-TB.  

PubMed

Drug-resistant tuberculosis has been reported since the early days of the introduction of chemotherapy. However, most of the evidence was limited to developed countries. In 1992, the Third World Congress on Tuberculosis concluded that there was little recent information on the global magnitude of multidrug-resistant tuberculosis (MDR-TB), defined as resistance to at least isoniazid and rifampicin. Through the WHO/IUATLD Global Project on Drug-Resistance Surveillance launched in 1994, a large number of reliable and accurate data have allowed us to understand the magnitude of the problem of MDR-TB. The data available suggest that globally MDR-TB is not a problem (median = 1% in 64 countries/geographical sites surveyed) of the same magnitude as that of drug-susceptible tuberculosis. However, MDR-TB is at critical levels in specific regions of the world. Hot spots for MDR-TB include Estonia, Latvia, the Oblasts of Ivanovo and Tomsk in Russia, and the provinces of Henan and Zhejiang Provinces in China. Trends confirm that MDR-TB is limited to local epidemics but the evidence is not yet irrefutable, as many countries have only provided short-term data. Two-thirds of the world's countries and, more importantly, half of the 22 tuberculosis high-burden countries, have not yet provided data. Mathematical modelling suggests that 3.2% (or 273,000) of the world's estimated new tuberculosis cases (95% confidence intervals: 185,000 and 414,000) were MDR-TB in 2000. Adoption of DOTS to prevent the generation of resistant strains and careful introduction of second-line drugs to treat patients with MDR are the top priorities for proper control/containment of MDR-TB. PMID:12758188

Espinal, Marcos A

2003-01-01

365

Photooxidation of dyed styrene-butadiene and natural rubbers  

Microsoft Academic Search

Dyed natural rubber (NR) and styrene-butadiene rubber (SBR) designed for outdoor applications were exposed to accelerated\\u000a artificial aging in xenon light. The aging results in the deterioration of the properties of the exposed surface material.\\u000a The ability of dyed polymers to withstand prolonged sunlight exposure without fading or undergoing any physical deterioration\\u000a is largely determined not only by the photochemical

D. Ruch; C. Becker; A. Riche; S. Etienne; J. Bour

2008-01-01

366

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

NASA Astrophysics Data System (ADS)

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

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

2011-07-01

367

Energy Dependence of the gamma Detection Efficiency for CaSO sub 4 (Dy) and BaSO sub 4 (Dy) Thermoluminescent Detectors.  

National Technical Information Service (NTIS)

The aim of the work was to make thermoluminescent detector with abnormal sensibility to low energy gamma-rays. Detectors made of BaSO sub 4 (Dy) phosphorus were synthesized. Response functions of BaSO sub 4 (Dy) and CaSO sub 4 (Dy) detectors were measured...

V. I. Tsovbun Y. Khenniger Kho Gi Khon

1983-01-01

368

Intensities and transition probabilities for selected DyI and DyII lines emitted from a ferroelectric plasma source  

NASA Astrophysics Data System (ADS)

An argon-dysprosium plasma was generated at atmospheric pressure between a ceramic ferroelectric plate and a dysprosium plate. The system of plates was connected to an acoustic frequency power supply. The plasma radiation was analyzed in the spectral range from 2500 to 6700 A by using a grating spectrograph with a linear dispersion of about 1 mm/A, adapted for photoelectric measurements. The emission spectrum of dysprosium was recorded and the intensities of more than 500 DyI and DyII lines were measured. For 133 DyI-lines and 228 DyII-lines the transition probabilities, absorption oscillator strengths and log(gifik) were determined. The obtained values were compared with the literature data.

Kusz, J.

1992-02-01

369

Precision measurement of the g-factor of the 2+ ?-vibrational state of160Dy and test of the F-spin purity  

NASA Astrophysics Data System (ADS)

The rotations of the 392-966 keV and the 299 966 keV directional correlations of160Dy in the static hyperfine field of Dy Tb have been measured with high precision. A neutron activated Tb single crystal was used which was magnetized to saturation at 4.2 K by an external magnetic field of 4.5 T applied in the direction of the b-axis. The agreement of both rotations proves that the relaxation of the 4 f-shell after the ?-decay takes less than 10 ps. A quantum mechanical calculation within the magnon model gave a relaxation time of the order of 1 ps. The g-factor of the 2+ ?-vibrational state was derived as 10050_2005_Article_BF01297722_TeX2GIFE1.gif g(2_? ^ + ) = + 0.317(12) and combining our results with Mssbauer data [24] on the magnetic splitting of the 2rot + state in the same environment we obtain 10050_2005_Article_BF01297722_TeX2GIFE2.gif g(2_? ^ + )/g(2_{rot}^ + ) = 0.82(3). . The results are discussed within the Bohr-Mottelson model and finally within the IBM-2 model in terms of F-spin purity.

Alfter, I.; Bodenstedt, E.; Knichel, W.; Schth, J.

1995-03-01

370

Measurement and systematic study of (n,x) cross sections for dysprosium (Dy), erbium (Er), and ytterbium (Yb) isotopes at 14.7 MeV neutron energy  

NASA Astrophysics Data System (ADS)

Background: Neutron activation cross sections for energies around 14 MeV are required for various applications. Because cross-section data for the rare-earth elements are too scarce, there is a need for their accurate measurement and refinement. The accuracy of the evaluation and cross-section trend studies can be improved with reliable experimental data too.Purpose: The purpose of the paper is to provide measurements of new cross-section data and earlier published cross-section data with much better accuracy for lanthanide elementsDy, Er, and Yband the re-evaluation of available systematics for (n,x) reactions.Methods: The cross sections for (n,x) reactions were measured at (d-t) neutron energies with the activation technique. Theoretical calculations of cross-section values have been performed with the talys-1.2 code.Results: The sets of cross sections for (n,p), (n,2n), and (n,?) reactions were analyzed and the systematics were tested over the 156 ? A ? 176 mass region. The 156Dy(n,p)156Tb and 162Er(n,p)162Ho(m+g) cross-section values at 14.7 MeV neutron energy are reported for the first time. The 176Yb(n,d+pn)175Tm, 176Yb(n,n?)172Er, 162,163Dy(n,x)162Tb, and 163,164Dy(n,x)163Tb cross sections are obtained with much better accuracy. The reevaluation of systematics for (n,p) cross sections and the reexamination of a presence of isotopic effect in the target nuclei mass range was performed. It was done based on original and earlier available data.Conclusions: Obtained experimental results can be used for nuclear reaction model testing and could be considered as supplementary ones for nuclear data evaluation. The straight-line systematic dependence for (n,?) cross section was confirmed. For Er isotopes, a clear isotopic effect was observed in case of (n,p) reactions and pointed out the necessity of reconsidering the systematics.

Dzysiuk, N.; Kadenko, A.; Kadenko, I.; Primenko, G.

2012-09-01

371

TB Incidence in an Adolescent Cohort in South Africa  

PubMed Central

Background Tuberculosis (TB) is a major public health problem globally. Little is known about TB incidence in adolescents who are a proposed target group for new TB vaccines. We conducted a study to determine the TB incidence rates and risk factors for TB disease in a cohort of school-going adolescents in a high TB burden area in South Africa. Methods We recruited adolescents aged 12 to 18 years from high schools in Worcester, South Africa. Demographic and clinical information was collected, a tuberculin skin test (TST) performed and blood drawn for a QuantiFERON TB Gold assay at baseline. Screening for TB cases occurred at follow up visits and by surveillance of registers at public sector TB clinics over a period of up to 3.8 years after enrolment. Results A total of 6,363 adolescents were enrolled (58% of the school population targeted). During follow up, 67 cases of bacteriologically confirmed TB were detected giving an overall incidence rate of 0.45 per 100 person years (95% confidence interval 0.290.72). Black or mixed race, maternal education of primary school or less or unknown, a positive baseline QuantiFERON assay and a positive baseline TST were significant predictors of TB disease on adjusted analysis. Conclusion The adolescent TB incidence found in a high burden setting will help TB vaccine developers plan clinical trials in this population. Latent TB infection and low socio-economic status were predictors of TB disease.

Mahomed, Hassan; Ehrlich, Rodney; Hawkridge, Tony; Hatherill, Mark; Geiter, Lawrence; Kafaar, Fazlin; Abrahams, Deborah Ann; Mulenga, Humphrey; Tameris, Michele; Geldenhuys, Hennie; Hanekom, Willem Albert; Verver, Suzanne; Hussey, Gregory Dudley

2013-01-01

372

T-SPOT.TB assay usage in adults and children.  

PubMed

The diagnosis and treatment of TB infection is one of the public health priorities. Until recently, diagnosis of TB infection has been based on the tuberculin skin test (TST). However, this is neither 100% sensitive nor specific for the diagnosis of TB infection owing to its many drawbacks. More recently, T-cell-based IFN-? release assays (IGRAs) have been developed. In this article, we review the clinical performance of one of the IGRAs, T-SPOT.TB assay, for the diagnosis of TB infection in adults and children. We discuss the principle of the assay, its utility in active TB diseases, latent TB infection and the performance of the test in specialized subgroups of patients, such as immunocompromised individuals. When compared with the TST, the T-SPOT.TB assay has better specificity in bacillus Calmette-Gurin-vaccinated individuals, and data suggest that T-SPOT.TB may be more sensitive than the TST. Data in groups at high risk of progression to disease support the idea that T-SPOT.TB performs better than the TST. In addition, application of T-SPOT.TB by using bodily fluids such as cerebrospinal fluid, bronchoalveolar lavage fluid and pleural fluid may offer new diagnostic approaches in extrapulmonary TB disease. Although IGRAs cannot distinguish active TB disease from latent TB infection, these assays perform better than the TST for the detection of TB infection. PMID:21745017

Soysal, Ahmet; Bakir, Mustafa

2011-07-01

373

Mass incarceration can explain population increases in TB and multidrug-resistant TB in European and central Asian countries  

Microsoft Academic Search

Several microlevel studies have pinpointed prisons as an important site for tuberculosis (TB) and multidrug-resistant TB in European and central Asian countries. To date, no comparative analyses have examined whether rises in incarceration rates can account for puzzling differences in TB trends among overall populations. Using longitudinal TB and cross-sectional multidrug-resistant TB data for 26 eastern European and central Asian

David Stuckler; Sanjay Basu; Martin McKee; Lawrence King

2008-01-01

374

Nuclear magnetic resonance of 155Gd and 157Gd nuclei in gadolinium iron garnet  

Microsoft Academic Search

The magnetic resonance of 155Gd and 157Gd nuclei was detected in GdIG at liquid helium temperature by a spin echo method. The resonance frequencies (40.5 and 54Mc\\/sec) correspond to the effective field of 338 kOe. This value is consistent with the known hyperfine coupling constant of Gd3+ in different compounds. The observed splittings were ascribed to quadrupole interaction.

Le Dang Kho

1969-01-01

375

TbENF is an Essential TbTFIIB-Interacting Trypanosomatid-Specific Factor  

PubMed Central

Trypanosoma brucei, the causative agent of African Sleeping sickness, is replete with unique biochemistry, including unusual features of gene transcription. The parasite also contains over 4500 non-annotated genes, representing novel biochemistry yet to be explored. Using tandem affinity purification (TAP)-tagged TbTFIIB, we identified and subsequently confirmed, one of the non-annotated Trypanosoma brucei proteins, Tb11.02.4300, as a TbTFIIB-interacting protein. The 49 kDa protein is nuclear and essential for parasite variability as determined by RNA interference studies; hence, the nomenclature T. brucei Essential Nuclear Factor (TbENF). TbENF is shown to interact with DNA in a sequence-independent fashion under the conditions examined. Furthermore, TbENF bears motifs associated with many eukaryotic transcription factors, such as a glutamine-rich region and a leucine zipper, yet TbENF is specific to trypanosomatids making it a potentially attractive therapeutic target. Taken together, our results suggest a role for TbENF in trypanosome gene transcription.

Solnoki, Kellie Whitecavage; Sing, Allison H.; Sofa, Caitlyn J.; Miller, Russell; Ogorzalek, Paulina A.; Penek, Hillary V.; Palenchar, Jennifer B.

2011-01-01

376

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

377

TB database 2010: overview and update.  

PubMed

The Tuberculosis Database (TBDB) is an online database providing integrated access to genome sequence, expression data and literature curation for TB. TBDB currently houses genome assemblies for numerous strains of Mycobacterium tuberculosis (MTB) as well assemblies for over 20 strains related to MTB and useful for comparative analysis. TBDB stores pre- and post-publication gene-expression data from M. tuberculosis and its close relatives, including over 3000 MTB microarrays, 95 RT-PCR datasets, 2700 microarrays for human and mouse TB related experiments, and 260 arrays for Streptomyces coelicolor. To enable wide use of these data, TBDB provides a suite of tools for searching, browsing, analyzing, and downloading the data. We provide here an overview of TBDB focusing on recent data releases and enhancements. In particular, we describe the recent release of a Global Genetic Diversity dataset for TB, support for short-read re-sequencing data, new tools for exploring gene expression data in the context of gene regulation, and the integration of a metabolic network reconstruction and BioCyc with TBDB. By integrating a wide range of genomic data with tools for their use, TBDB is a unique platform for both basic science research in TB, as well as research into the discovery and development of TB drugs, vaccines and biomarkers. PMID:20488753

Galagan, James E; Sisk, Peter; Stolte, Christian; Weiner, Brian; Koehrsen, Michael; Wymore, Farrell; Reddy, T B K; Zucker, Jeremy D; Engels, Reinhard; Gellesch, Marcel; Hubble, Jeremy; Jin, Heng; Larson, Lisa; Mao, Maria; Nitzberg, Michael; White, Jared; Zachariah, Zachariah K; Sherlock, Gavin; Ball, Catherine A; Schoolnik, Gary K

2010-05-20

378

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

SciTech Connect

The magnetic structures of RSn{sub 1+x}Ge{sub 1-x} (R=Tb, Dy, Ho and Er, x{approx}0.1) compounds have been determined by neutron diffraction studies on polycrystalline samples. The data recorded in a paramagnetic state confirmed the orthorhombic crystal structure described by the space group Cmcm. These compounds are antiferromagnets at low temperatures. The magnetic ordering in TbSn{sub 1.12}Ge{sub 0.88} is sine-modulated described by the propagation vector k=(0.4257(2), 0, 0.5880(3)). Tb magnetic moment equals 9.0(1) {mu}{sub B} at 1.62 K. It lies in the b-c plane and form an angle {theta}=17.4(2) deg. with the c-axis. This structure is stable up to the Neel temperature equal to 31 K. The magnetic structures of RSn{sub 1+x}Ge{sub 1-x}, where R are Dy, Ho and Er at low temperatures are described by the propagation vector k=(1/2, 1/2, 0) with the sequence (++-+) of magnetic moments in the crystal unit cell. In DySn{sub 1.09}Ge{sub 0.91} and HoSn{sub 1.1}Ge{sub 0.9} magnetic moments equal 7.25(15) and 8.60(6) {mu}{sub B} at 1.55 K, respectively. The moments are parallel to the c-axis. For Ho-compound this ordering is stable up to T{sub N}=10.7 K. For ErSn{sub 1.08}Ge{sub 0.92}, the Er magnetic moment equals 7.76(7) {mu}{sub B} at T=1.5 K and it is parallel to the b-axis. At T{sub t}=3.5 K it tunes into the modulated structure described by the k=(0.496(1), 0.446(4), 0). With the increase of temperature there is a slow decrease of k{sub x} component and a quick decrease of k{sub y} component. The Er magnetic moment is parallel to the b-axis up to 3.9 K while at 4 K and above it lies in the b-c plane and form an angle 48(3) deg. with the c-axis. In compounds with R=Tb, Ho and Er the magnetostriction effect at the Neel temperature is observed. - Graphical abstract: The magnetic structures of RSn{sub 1+x}Ge{sub 1-x} (R=Tb, Dy, Ho and Er, x{approx}0.1) compounds have been determined by neutron diffraction studies on polycrystalline samples. The magnetic ordering in TbSn{sub 1.12}Ge{sub 0.88} (a) is sine-modulated described by the propagation vector k=(0.426, 0, 0.588). The magnetic structures of RSn{sub 1+x}Ge{sub 1-x} where R are Dy (b), Ho (b) and Er (c) at temperatures close to 1.5 K are described by the propagation vector k=(1/2, 1/2, 0) with the sequence (++-+) of magnetic moments in the crystal unit cell. For Ho- and Dy-compound this ordering is stable up to T{sub N} while for Er-compound at T{sub t}=3.5 K it tunes into a modulated structure (d). Highlights: > We determine crystal and magnetic structures of RSn{sub 1+x}Ge{sub 1-x} (R=Tb, Dy, Ho, Er, x{approx}0.1) compounds. > We compare the results with those for RT{sub x}X{sub 2} (X=Ge, Sn) compounds. > We examine the influence of other components (T, Sn, Ge) on magnetic ordering in R-sublattices. > Magnetic ordering in RSn{sub 1+x}Ge{sub 1-x} compounds is similar to those observed in RT{sub x}X{sub 2} compounds. > Other elements (T, Sn, Ge) have not got significant influence on stability of magnetic ordering.

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

2011-07-15

379

Synthesis, structure and magnetic properties of Fe-Gd nanocapsules coated with B2O3/H3BO3 and Fe3BO5+GdBO3  

NASA Astrophysics Data System (ADS)

Nanocapsules consisting of B2O3/H3BO3 encapsulating Fe-Gd cores have been synthesized by an arc-discharge process using metal-boron alloys as cathode. Most of the nanocapsules have a well-constructed shell/core structure with a uniform B2O3/H3BO3 shell. Heat-treatment induces reactions between the shell and the core, resulting in the formation of a Fe3BO5+GdBO3 matrix embedded with Fe nanoparticles, reduction of the metallic-core size and decrease of the blocking temperature TB. Above TB, the magnetization curves plotted vs. H/T overlap and show zero coercivity. Below TB, the coercivity shows a linear dependence when plotted vs. T1/2. However, the coercivity-T1/2 curve below 60 K has a different slope from that above 60 K, indicating the existence of two different magnetic phases in the nanocapsules. Different from bulk Fe3BO5, nanoscale Fe3BO5 particles have a lower transition temperature to the weak-ferromagnetic state, and magnetic hysteresis is absent due to size effects.

Si, P. Z.; Brck, E.; Zhang, Z. D.; Tegus, O.; Buschow, K. H. J.; Zhang, W. S.; Klaasse, J. C. P.; de Boer, F. R.

2004-11-01

380

The magnetic state of 1212-type ruthenocuprate in magnetocaloric and magnetoresistivity measurements of polycrystalline samples of RuSr2Gd1-xCexCu2O8 and Ru1-xSr2GdCu2O8  

Microsoft Academic Search

The magnetic properties of superconducting Ru1-xSr2GdCu2O8 (x = 0, 0.02) and non-superconducting RuSr2Gd1-xCexCu2O8 (x = 0.07, 0.1) were investigated by means of magnetocaloric experiments with complementary magnetoresistivity and ac susceptibility measurements. The isothermal magnetocaloric coefficient MT(B) assumes positive values in a broad range of temperatures (20 K<=T<=231 K) and magnetic fields (0 T<=B<=13 T), i.e. also in the magnetically ordered

Piotr W. Klamut; Tomasz Plackowski

2009-01-01

381

Exchange interactions in amorphous Gd-Fe alloys  

NASA Astrophysics Data System (ADS)

The strengths of the Gd-Gd, Gd-Fe and Fe-Fe exchange couplings have been estimated from ordering temperatures for the amorphous Gd-T (T=Cu, Al and Fe) systems. The obtained Gd-Gd and Gd-Fe exchange interactions always increase with increasing Gd-concentration. These results are associated to the 5d-electron density. The Fe-Fe coupling, however, was discussed in terms of the negative interactions between the Fe-Fe pairs with the closest inter-atomic spacing.

Danh, T. M.; Duc, N. H.; Thuy, N. P.

1998-05-01

382

The GD Concentration Dependence of the Magnetic Properties of Room Temperature Ferromagnetic ZNO:GD Semiconductor  

NASA Astrophysics Data System (ADS)

We present structural and magnetic properties of ZnO films doped with rare-earth Gd ions at various concentrations, achieved by ion implantation technique and pulsed laser deposition (PLD) on ZnO (0001) single crystals and sapphire. X-ray diffraction shows Gd doping in ZnO and crystal quality degrades with increasing Gd concentration. Magnetization as a function of temperature revealed a positive magnetization at 305 K and a concave trend was observed for all samples for both implanted and PLD grown samples. The highest saturation magnetization was achieved for Gd concentration of x = 7.9 % (0.7 B/Gd) and at dosage of 9.0 1015 cm-2 (2.6 B/Gd) for the PLD grown and implanted samples, respectively. We believe that the Gd ion solubility limit in the implanted and PLD grown samples, of around 3% and 7.9%, respectively, are reached.

Lim, S. T.; Song, W. D.; Teo, K. L.; Liew, T.; Chong, T. C.

383

In-beam study of 145Tb  

NASA Astrophysics Data System (ADS)

The high-spin states of 145Tb have been studied in the 118Sn(32S, 1p4n) reaction at 32S energies from 161 to 175 MeV using techniques of in-beam ?-ray spectroscopy. Measurements of ?-ray excitation functions and ?-?-t coincidences were performed with 12 BGO(AC)HPGe detectors. Based on the measured results of ?-? coincidences, ?-ray anisotropies and DCO ratios, a level scheme for 145Tb was established for the first time. The observed excited states show typical irregular pattern in a spherical nucleus, and the low-lying levels have been interpreted qualitatively with a particle-core coupling.

Zhou, X. H.; Zheng, Y.; Zhang, Y. H.; Liu, Z.; Pan, Q. Y.; Gan, Z. G.; Hayakawa, T.; Oshima, M.; Toh, T.; Shizuma, T.; Katakura, J.; Hatsukawa, Y.; Matsuda, M.; Kusakari, H.; Sugawara, M.; Furuno, K.; Komatsubara, T.

384

159Tb NMR in Tb(Fe1-xCox)2 and Tb0.8Y0.2Fe2 Intermetallic Compounds  

NASA Astrophysics Data System (ADS)

Spin echo NMR measurements on 159Tb have been done in magnetically ordered state of the cubic Laves phase compounds Tb(Fe1-xCox)2 and Tb0.8Y0.2Fe2. Satellite structures observed in the compounds with x?0.2 are assigned to various Fe, Co configurations in the nearest neighbor shell. The resonance frequency corresponding to the -1/2{?ftrightarrow}1/2 transition decreases from 3798 3 MHz in TbFe2 to 3387 3 MHz in TbCo2 with increasing Co concentration. The frequency differences between the lines corresponding to the -3/2{?ftrightarrow}-1/2 and -1/2{?ftrightarrow}1/2 transitions are 685 6 MHz in TbFe2 and 675 7 MHz in TbCo2.

Shimizu, Kenji; Okeya, So-haku

1986-04-01

385

Valence photoelectron spectroscopy of Gd silicides  

SciTech Connect

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

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

1990-02-15

386

Two distinct Dy-isophthalates induced by different solvents  

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

387

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; Gurette, B; Puymirat, J; Yaffe, D; Tom, F M; Fardeau, M; Fiszman, M; Schwartz, K; Tremblay, J P

1999-05-01

388

Validation of large-scale, monochromatic UV disinfection systems for drinking water using dyed microspheres  

Microsoft Academic Search

Dyed microspheres have been developed as a new method for validation of ultraviolet (UV) reactor systems. When properly applied, dyed microspheres allow measurement of the UV dose distribution delivered by a photochemical reactor for a given operating condition. Prior to this research, dyed microspheres had only been applied to a bench-scale UV reactor. The goal of this research was to

E. R. Blatchley III; C. Shen; O. K. Scheible; J. P. Robinson; K. Ragheb; D. E. Bergstrom; D. Rokjer

2008-01-01

389

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

390

Optical properties of lead borate glasses containing Dy3+ ions  

NASA Astrophysics Data System (ADS)

Optical properties of lead borate glasses containing Dy3+ ions were examined using absorption and luminescence measurements and theoretical calculations based on the Judd-Ofelt framework and the Inokuti-Hirayama model. The luminescence spectra show two characteristic bands at 480 and 573 nm, which are due to 4F9/2-6H15/2 (blue) and 4F9/2-6H13/2 (yellow) transitions of trivalent Dy3+ ions. The yellow/blue luminescence and its decay were analyzed as a function of activator concentration.

Pisarska, Joanna

2009-07-01

391

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

392

Strengthening TB surveillance system in India: Way forward for improving estimates of TB incidence  

PubMed Central

One of the key indicators used under Indias TB control program is the DOTS case detection rate of new sputum smear positive TB whose estimates in India are based on incidence estimates derived from Styblos rule. Styblos rule was formulated in an era without well-established tuberculosis control program, effective tuberculosis drugs, and emergence of TB-HIV coinfection, so today it does not reflect the true incidence of TB. Considering various loopholes in different methods of measurement of incidence (prevalence surveys of disease/ infection, vital registration system and Styblos rule), strengthening of existing surveillance system is the best tool to obtain correct estimates of tuberculosis incidence in India.

Sharma, Rinku; Jain, Vivek; Singh, Saudan

2011-01-01

393

Magnetic properties of hexanuclear lanthanide(III) clusters incorporating a central ?6-carbonate ligand derived from atmospheric CO2 fixation.  

PubMed

Three isostructural hexanuclear lanthanide(III) clusters are reported (Ln(III) = Gd, Tb, and Dy). The metallic core of each complex displays an unusual arrangement of ions, which is stabilized by a ?(6)-carbonate ligand. Magnetic studies show that the Ln(III) ions in each compound are weakly exchange coupled, with the Tb and Dy analogues displaying single-molecule-magnet behavior. PMID:22414239

Langley, Stuart K; Moubaraki, Boujemaa; Murray, Keith S

2012-03-13

394

Scissors Mode in Gd Nuclei  

NASA Astrophysics Data System (ADS)

Spectra of ? rays following neutron capture at isolated resonances of 6 stable Gd isotopes were measured with highly segmented BaF2 detector DANCE at the Los Alamos LANSCE spallation neutron source. The main emphasis was put on studying the ?-cascade decay of neutron resonances to get unique information on photon strength. An analysis of the accumulated ?-ray spectra within the extreme statistical model leads to an inescapable conclusion that scissors mode resonances are built not only on the ground-state, but also on excited levels in all product nuclei studied. The results on summed B(M1)? strength and energy of the scissors mode are compared with systematics of scissors mode parameters for the ground-state transitions deduced from nuclear resonance fluorescence measurements. A specific feature of our experiments is the investigation of scissors mode of odd nuclei, for which the nuclear resonance fluorescence provides only limited information.

Kroll, J.; Baramsai, B.; Becker, J. A.; Be?v?, F.; Bredeweg, T. A.; Couture, A.; Chyzh, A.; Dashdorj, D.; Haight, R. C.; Jandel, M.; Krti?ka, M.; Mitchell, G. E.; O'Donnell, J. M.; Parker, W.; Rundberg, R. S.; Ullmann, J. L.; Vieira, G. J.; Walker, C. L.; Wilhelmy, J. B.; Wouters, J. M.; Wu, C. Y.

2012-02-01

395

Magnetic Moment, Susceptibility, and Electrical Resistivity of Dilute Paramagnetic Palladium-Rare-Earth Alloys  

Microsoft Academic Search

The magnetic properties and low-temperature electrical resistivity are reported for dilute alloys of the Pd1-xRx system where R=Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, or Y, and x is generally 0.01 or less. Alloys with R=Ce, Gd, Dy, or Er are examined over a wide range of concentrations. The quantities measured were the magnetic

R. P. Guertin; H. C. Praddaude; S. Foner; E. J. McNiff; B. Barsoumian

1973-01-01

396

Muscle regeneration and mitochondrial calmitine increase in the dystrophic dy/dy mouse after intramuscular chlorpromazine injection.  

PubMed

We studied the effect of chlorpromazine injection on the gastrocnemius muscles of C57BL/6J dy/dy dystrophic mice. Changes in mitochondrial calmitine concentrations and differences in microscopy studies, fibre typing and morphometry were compared in gastrocnemius muscles of dystrophic and control mice before and 2 and 21 days after injection. In both cases, calmitine reduction associated with muscle degeneration was observed 2 days after drug injection. Calmitine then increased, reaching a level at day 21 nearly identical to that of controls before injection. This increase was associated with muscle regeneration. These results clearly indicate that dystrophic mouse muscle can regenerate calmitine after drug-induced damage. PMID:8525804

Lucas-Heron, B; Louboutin, J P; Ollivier, B; Schmitt, N

1995-01-01

397

Enhancement of the curie temperature due to the coupling between Fe itinerant electrons and Dy localized electrons in DyFe2Zn20  

NASA Astrophysics Data System (ADS)

The temperature dependences of the magnetization and the specific heat of the ferromagnetic compound DyFe2Zn20 have been measured in detail in various magnetic fields. We have observed anomalous magnetic behaviors, i.e., a strong anisotropy at 2 K, the disappearance of this anisotropy at temperatures between approximately 30 K and T c , and an anomalous behavior of the specific heat in magnetic fields at temperatures near 20 K. These anomalous phenomena have been analyzed based on the strong exchange interaction between the Fe itinerant electrons and the Dy localized electrons, as well as the crystalline electric field, the Zeeman energy, and an usual exchange interaction between two Dy atoms. The higher T c of DyFe2Zn20 compared with that of DyRu2Zn20 is caused by this exchange interaction between the Fe and the Dy atoms.

Isikawa, Yosikazu; Mizushima, Toshio; Miyamoto, Souta; Kumagai, Keigou; Nakahara, Mako; Okuyama, Hiroaki; Tayama, Takashi; Kuwai, Tomohiko; Lejay, Pascal

2013-08-01

398

Field-dependent phase transitions and magnetization of the type II-antiferromagnets TbP and TbSb  

Microsoft Academic Search

By means of a computer-controlled magnetometer the magnetization has been investigated between 2 and 100 K in fields up to 140 kOe applied parallel to the easy -axes of TbP (TN = 7.1 K) and TbSb (TN = 15.5 K. The first (TbP) and second (TbSb) kinds of the transition from para- to type II-antiferromagnetism are unchanged up to the

A. Buschbeck; Ch. Chojnowski; J. Ktzler; R. Sonder; G. Thummes

1987-01-01

399

Magnetism in Gd-W films  

SciTech Connect

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

Gadioli, Giovana Z.; Rouxinol, Francisco P.; Gelamo, Rogerio V.; Santos, Adenilson O. dos; Cardoso, Lisandro P.; Bica de Moraes, Mario A. [Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas, 13083-970 Campinas, Sao Paulo (Brazil)

2008-05-01

400

Raman Scattering and Theoretical Studies of Jahn-Teller Induced Phase Transitions in Some Rare-Earth Compounds  

Microsoft Academic Search

The rare-earth crystals DyVO4, DyAsO4, and TbVO4 undergo structural phase transitions at 14, 12 and 34 K respectively induced by a cooperative Jahn-Teller effect. An experimental investigation of the phase changes has been made using Raman scattering methods. For purposes of comparison, the Raman spectra of DyPO4, YVO4 and GdVO4 (which do not undergo phase transitions) have also been measured.

R. J. Elliott; R. T. Harley; W. Hayes; S. R. P. Smith

1972-01-01

401

Temperature sensing above 1000 C using Cr-doped GdAlO3 spin-allowed broadband luminescence  

NASA Astrophysics Data System (ADS)

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 2E to 4A2 radiative transition (R line) has typically restricted their use for temperature sensing to below 600 C. Thermal quenching of the broadband 4T2 to 4A2 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 2E energy level acts as a reservoir to thermally populate the higher shorter-lived 4T2 energy level and because the activation energy for nonradiative crossover relaxation from the 4T2 level to the 4A2 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, J. I.; Chambers, M. D.

2013-09-01

402

Controlled synthesis and characterization of large-scale, uniform Dy(OH)3 and Dy2O3 single-crystal nanorods by a hydrothermal method  

Microsoft Academic Search

Large-scale and uniform Dy(OH)3 nanorods have been successfully prepared by a simple hydrothermal method. Subsequent thermal decomposition of the as-prepared Dy(OH)3 nanorods produced Dy2O3 nanorods. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA) and differential thermal analysis (DTA) have been employed to characterize the products. XRD and SAED

Gui Wang; Zhengde Wang; Yunxia Zhang; Guangtao Fei; Lide Zhang

2004-01-01

403

Antiferromagnetic ordering in REM cobaltite GdCoO3  

NASA Astrophysics Data System (ADS)

Temperature and magnetic-field dependences of the static magnetization of polycrystalline cobaltite GdCoO3 have been measured. The magnetic properties of the GdCoO3 sample have been studied in the paramagnetic and antiferromagnetic states. The magnetic phase diagram has been constructed. The exchange field between the Gd-Gd sublattices and the anisotropy field have been estimated.

Dudnikov, V. A.; Velikanov, D. A.; Kazak, N. V.; Michel, C. R.; Bartolome, J.; Arauzo, A.; Ovchinnikov, S. G.; Patrin, G. S.

2012-01-01

404

Missed opportunities in TB diagnosis: a TB Process-Based Performance Review tool to evaluate and improve clinical care  

Microsoft Academic Search

BackgroundTraditional tuberculosis (TB) treatment outcome measures, such as cure rate, do not provide insight into the underlying reasons\\u000a for missing clinical targets. We evaluated a TB Process-Based Performance Review (TB-PBPR) tool, developed to identify \\

Nigel Field; Jill Murray; Michelle L Wong; Rob Dowdeswell; Ntomboxolo Dudumayo; Lesego Rametsi; Neil Martinson; Marc Lipman; Judith R Glynn; Pam Sonnenberg

2011-01-01

405

Development of an Au-Dy-Si liquid alloy ion source for focussed ion beam implantation  

NASA Astrophysics Data System (ADS)

A liquid metal ion source (LMIS) based on the Au78.2Dy8Si13.8 alloy was developed for focussed ion beam implantation of Dy ions. The mass spectrum of the LMIS shows the presence of Si2+, Si+, Dy3+, Dy2+, Au2+, Au+, Au32+ and Au2+ ions. The Au-Dy-Si LMIS shows high stability and long time operational capacity. A simple calculational technique for eutectic compositions of ternary alloys for LMIS is suggested on the base of binary phase diagrams of the elements used.

Melnikov, A.; Gerya, T.; Hillmann, M.; Kamphausen, I.; Oswald, W.; Stauche, P.; Wernhardt, R.; Wieck, A. D.

2002-10-01

406

Surface activation of dyed fabric for cellulase treatment.  

PubMed

Surface activation of fabric made from cellulose fibres, such as viscose, lyocell, modal fibres and cotton, can be achieved by printing of a concentrated NaOH-containing paste. From the concentration of reducing sugars formed in solution, an increase in intensity of the cellulase hydrolysis by a factor of six to eight was observed, which was mainly concentrated at the activated parts of the fabric surface. This method of local activation is of particular interest for modification of materials that have been dyed with special processes to attain an uneven distribution of dyestuff within the yarn cross-section, e.g., indigo ring-dyed denim yarn for jeans production. Fabrics made from regenerated cellulose fibres were used as model substrate to express the effects of surface activation on indigo-dyed material. Wash-down experiments on indigo-dyed denim demonstrated significant colour removal from the activated surface at low overall weight loss of 4-5%. The method is of relevance for a more eco-friendly processing of jeans in the garment industry. PMID:21491605

Schimper, Christian B; Ibanescu, Constanta; Bechtold, Thomas

2011-04-13

407

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

408

Structure of DySi2 nanowires on Si(001)  

NASA Astrophysics Data System (ADS)

Free-standing dysprosium-silicide nanowires can be formed on Si(001) by self assembly. It is shown that the wires consist of anisotropically strained hexagonal DySi2 with the c axis aligned perpendicular to the wires. The surface is characterized by a 21 reconstruction due to the formation of Si dimer chains.

Preinesberger, C.; Becker, S. K.; Vandr, S.; Kalka, T.; Dhne, M.

2002-02-01

409

Feasibility Study of VUV Sensitization Effect of Tb3+  

Microsoft Academic Search

The possibility to use Tb as luminescence sensitizer for enhancement of the conversion efficiency of vacuum-ultraviolet (VUV) radiation into visible light was examined. We studied the luminescence properties of K3Tb(PO4)2 and Ba3Tb(PO4)3 activated by Eu, and of SrAl12O19 co-doped with Mn and Tb at excitation over the 120 to 300nm wavelength range. It is shown that Tb ions, exhibiting a

V. B. Mikhailik; H. Kraus

2010-01-01

410

Gd116Co49Sn118: A Complex Intermetallic Phonon-Glass/Electron-Crystal  

NASA Astrophysics Data System (ADS)

State-of-the art thermoelectric devices today operate at very low efficiencies and are expensive to produce. However, the growing need for alternate energy sources based on novel technologies has brought thermoelectrics to the forefront of applied materials research. Thermoelectrics could have a significant impact in this area, if their performance is significantly enhanced to a figure of merit (ZT) above 1.5. Our research focuses on the growth and structure-property relationships of intermetallics, specifically crystal structures with large lattice parameters that contain heavy atoms. These materials may be good thermoelectric candidates due to their potentially low lattice thermal conductivities and enhanced Seebeck values resulting from polar intermetallic properties. We have recently grown Gd116Co49Sn118 (Fm-3m, a 30.2 ), a compound related to the Dy117Co57Sn112 structure type. Physical property measurements indicate that this is an ambipolar semiconductor with an exceptionally low lattice thermal conductivity (?l 0.5 W/m-K). The observed phonon-glass/electron-crystal properties make Gd116Co49Sn118 and its analogues potential thermoelectric candidates.

Schmitt, Devin; Haldolaarachchige, Neel; Xiong, Yimin; Jin, Rongying; Young, David; Chan, Julia

2011-03-01

411

Interface state and coercivity in Nd-Fe-B/Dy films  

NASA Astrophysics Data System (ADS)

We fabricated a model interface system, which consised of a Nd2Fe14B layer with Dy overlayers, in order to study the relationship between the microstructure near the interface and the coercivity. The coercivity H c of the 1-m-thick Nd-Fe-B films with a Dy overlayer was enhanced by thermal diffusion of Dy atoms from the film's surface into the Nd-Fe-B layer. The Nd-Fe-B/Dy films annealed at 700 C showed a significant increase in the H c of up to about 17 kOe. The maximum increase in the value of the coercivity ? H c of the annealed films with a Dy overlayer was approximately 13 kOe. The XRD measurement suggested the existence of rare-earth oxides (NdO and Dy2O3) in the Dy-coated films with high value of the ? H c .

Umezawa, Jin; Sakai, Yoshiki; Koike, Kunihiro; Ogawa, Daisuke; Mizuno, Yoshiyuki; Kato, Hiroaki; Miyazaki, Takamichi; Ando, Yasuo

2013-08-01

412

Effects of composition and thermal treatment on infrared transmission of Dy-?-sialon  

Microsoft Academic Search

By spark plasma sintering (SPS) and post-sintering thermal treatment at 1700C for 7 and 17 h, respectively, the infrared transmissions of Dy-?-sialon with three compositions, Dy0.33Si9.3Al2.7O1.7N14.3, Dy0.4Si10.2Al1.8O0.6N15.4 and Dy0.67Si9Al3O1N15, (abbreviated as Dy1017, Dy1206 and Dy2010, respectively), in 15004000 cm?1 wave number (6.62.5 ?) regions were investigated. The results showed that the second crystallized phase, the sizes of ?-sialon grains, the

Xinlu Su; Peiling Wang; Weiwu Chen; Zhijian Shen; Mats Nygren; Yibing Cheng; Dongsheng Yan

2004-01-01

413

Magnetic Transport Properties in GdBa2Cu3- x Ru x O7- ? Superconducting Phase  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

414

Optical switching properties from isotherms of Gd and GdMg hydride mirrors  

NASA Astrophysics Data System (ADS)

Concentration-pressure isotherms were measured together with the optical transmission in polycrystalline Gd and GdMg thin-film switchable mirrors. Formation plateaus in GdMg alloys, corresponding to gadolinium dihydride and trihydride as well as magnesium dihydride have been found. From these, the formation enthalpies could be calculated. These results show that the GdMg alloys are phase separated. From the onset of the transmission we conclude that the formation of gadolinium trihydride is the final stage in the switching process.

Di Vece, M.; Zevenhuizen, S. J. M.; Kelly, J. J.

2002-08-01

415

Mass incarceration can explain population increases in TB and multidrug-resistant TB in European and central Asian countries  

PubMed Central

Several microlevel studies have pinpointed prisons as an important site for tuberculosis (TB) and multidrug-resistant TB in European and central Asian countries. To date, no comparative analyses have examined whether rises in incarceration rates can account for puzzling differences in TB trends among overall populations. Using longitudinal TB and cross-sectional multidrug-resistant TB data for 26 eastern European and central Asian countries, we examined whether and to what degree increases in incarceration account for differences in population TB and multidrug-resistant TB burdens. We find that each percentage point increase in incarceration rates relates to an increased TB incidence of 0.34% (population attributable risk, 95% C.I.: 0.100.58%, P < 0.01), after controlling for TB infrastructure; HIV prevalence; and several surveillance, economic, demographic, and political indicators. Net increases in incarceration account for a 20.5% increase in TB incidence or nearly three-fifths of the average total increase in TB incidence in the countries studied from 1991 to 2002. Although the number of prisoners is a significant determinant of differences in TB incidence and multidrug-resistant TB prevalence among countries, the rate of prison growth is a larger determinant of these outcomes, and its effect is exacerbated but not confounded by HIV. Differences in incarceration rates are a major determinant of differences in population TB outcomes among eastern European and central Asian countries, and treatment expansion alone does not appear to resolve the effect of mass incarceration on TB incidence.

Stuckler, David; Basu, Sanjay; McKee, Martin; King, Lawrence

2008-01-01

416

Interleukin2 Binds to Ganglioside GD 1b  

Microsoft Academic Search

We have developed a solid matrix immunoassay to determine the binding of interleukin-2 (IL-2) to specific gangliosides. The assay establishes that recombinant human IL-2 binds to ganglioside GD1b but not to any other gangliosides (GM1, GM2, GM3, GD1a, GD2, GD3, and GT1b). The binding varies with the ratio of GD1b and IL-2. This assay enables distinguishing the nature of the

Mepur H. Ravindranath; Alexandra Gonzales; Daniel Soh; Kevin Nishimoto; Wai-Yin Tam; Anton Bilchik; Donald L. Morton; Steven O'Day

2001-01-01

417

Acetylation Suppresses the Proapoptotic Activity of GD3 Ganglioside  

Microsoft Academic Search

GD3 synthase is rapidly activated in different cell types after specific apoptotic stimuli. De novo synthesized GD3 accumulates and contributes to the apoptotic program by relocating to mito- chondrial membranes and inducing the release of apoptogenic factors. We found that sialic acid acetylation suppresses the proapoptotic activity of GD3. In fact, unlike GD3, 9-O-acetyl-GD3 is completely ineffective in inducing cytochrome

Florence Malisan; Luigi Franchi; Barbara Tomassini; Natascia Ventura; Ivano Cond; Maria Rita Rippo; Alessandra Rufini; Laura Liberati; Claudia Nachtigall; Bernhard Kniep; Roberto Testi

2002-01-01

418

Au111-based nanotemplates by gd alloying.  

PubMed

A new class of nanostructured templates is obtained by submitting Au111 films to high-temperature vapor deposition of Gd in ultrahigh vacuum. In a low coverage regime, Gd atoms are embedded in the topmost Au layer, inducing a structural transformation of the herringbone reconstruction to create a network of trigons. At higher dose, the reactive deposition of Gd leads to the formation of an atomically perfect GdAu2 surface compound characterized by a long-range periodic Moire pattern. Both the trigon and Moire lattices are highly ordered nanostructures, which turned out to be robust templates to grow metal nanodots. As a test example, Co was deposited at room temperature, forming uniform dots that faithfully arrange by following the underlying trigons or Moire periodicity. For the latter, one can achieve nanodot arrays that exhibit record areal density. PMID:20146459

Corso, Martina; Fernndez, Laura; Schiller, Frederik; Ortega, Jos Enrique

2010-03-23

419

Strong dichroism in the Dy 3d-->4f x-ray absorption at Dy/Si(111) interfaces  

NASA Astrophysics Data System (ADS)

We report experimental evidence for strong 3d-->4f x-ray-absorption dichroism in rare-earth ions on a nonmagnetic substrate: Dy on Si(111)77. The results are discussed by evaluating the role of the crystal-field splitting of the ground state as an alternative to the Zeeman splitting underlying the magnetic x-ray dichroism theory.

Sacchi, Maurizio; Sakho, Oumar; Rossi, Giorgio

1991-01-01

420

Gaps in the GD-1 Star Stream  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01