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1

Multiferroicity in orthorhombic R Mn O3 (R =Dy ,Tb , and Gd ) under high pressure  

NASA Astrophysics Data System (ADS)

The hydrostatic pressure effect on multiferroic properties of rare-earth manganites R Mn O3 (R =Dy ,Tb , and Gd ) with the P b n m orthorhombic structure was investigated by using a diamond anvil cell. Under high pressure, all of these manganites were found to exhibit ferroelectricity in which spontaneous polarization (?100? C /c m2) develops along the a axis. The application of a magnetic field B along the a axis to the high-pressure ferroelectric phase causes a drastic change in the electric polarization P . Especially in GdMn O3 , the B -induced change in P reached ? P (B ) =1.3 ? C /c m2 . A possible origin of the observed R -dependent pressure effect is discussed.

Aoyama, Takuya; Iyama, Ayato; Shimizu, Katsuya; Kimura, Tsuyoshi

2015-02-01

2

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)Å and c=3.8877(2)Å. The crystal structure for the isostructural compound Gd6Ni15As10 has been determined using

Volodymyr Babizhetskyy; Kurt Hiebl; Arndt Simon

2006-01-01

3

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

4

Specific heat and magnetization studies of RMnO3 (R=Sm, Eu, Gd, Tb and Dy) multiferroics  

NASA Astrophysics Data System (ADS)

A series of multiferroic materials with the compositional formula RMnO3 (where R=Sm, Eu, Gd, Tb and Dy) were prepared by the well-known citrate gel technique. After characterizing the samples structurally, a systematic investigation of specific heat and magnetization studies were performed over the temperature range 4-300 K with different magnetic fields. Based on these studies, it was found that all the samples exhibit a transition in the temperature region 39-54 K and the transition is attributed to ordering of Mn3+ ions (TNMn3+). Further, the samples GdMnO3, TbMnO3 and DyMnO3 were found to exhibit another transition (Tlock) in the temperature range 20-29 K. Finally, yet another transition was exhibited by all the samples and it is attributed to the antiferromagnetic (AF) ordering of rare-earth ion moments (TNR3+). The entropy at the AF transition TNMn3+ was computed. Finally, using the specific heat data, the Debye temperature values were also calculated.

Pavan Kumar, N.; Lalitha, G.; Venugopal Reddy, P.

2011-04-01

5

Photoluminescence properties of RE3+-activated Na3GdP2O8 (RE3+ = Tb3+, Dy3+, Eu3+, Sm3+) under VUV excitation  

NASA Astrophysics Data System (ADS)

RE3+-activated monoclinic Na3GdP2O8 (RE3+ = Tb3+, Dy3+, Eu3+, Sm3+) phosphors have been synthesized by a solid-state reaction method. Their photoluminescence properties in the vacuum ultraviolet (VUV) region were investigated. By analyzing their excitation spectra, the host-related absorption band was determined to be around 166 nm. The f-d transition bands and the charge transfer bands for Na3GdP2O8:RE3+ (RE3+ = Tb3+, Dy3+, Eu3+, Sm3+) were assigned and corroborated. For the sample Na3GdP2O8:5%Tb3+, the strong bands at around 202 and 221 nm are assigned to the 4f-5d spin-allowed transitions and the weak band at 266 nm is related to the spin-forbidden transition of Tb3+. For Na3GdP2O8:5%Dy3+, the broad band at 176 nm could be related to the f-d transitions of Dy3+ and the O2- ? Dy3+ charge transfer band (CTB) besides the host-related absorption. In the excitation spectrum of Eu3+ doped sample, the O2- ? Eu3+ CTB is observed to be at 245 nm. For the Sm3+ doped sample, the O2- ? Sm3+ CTB is not distinguished obviously and is overlapped with the host-related absorption band.

Zhang, Feng; Wang, Yuhua; Wen, Yan; Wang, Dan; Tao, Ye

2011-01-01

6

Synthesis, structures, and magnetic properties of face-sharing heterodinuclear Ni(II)-Ln(III) (Ln = Eu, Gd, Tb, Dy) complexes.  

PubMed

Heterodinuclear [(Ni (II)L)Ln (III)(hfac) 2(EtOH)] (H 3L = 1,1,1-tris[(salicylideneamino)methyl]ethane; Ln = Eu, Gd, Tb, and Dy; hfac = hexafluoroacetylacetonate) complexes ( 1.Ln) were prepared by treating [Ni(H 1.5L)]Cl 0.5 ( 1) with [Ln(hfac) 3(H 2O) 2] and triethylamine in ethanol (1:1:1). All 1.Ln complexes ( 1.Eu, 1.Gd, 1.Tb, and 1.Dy) crystallized in the triclinic space group P1 (No. 2) with Z = 2 with very similar structures. Each complex is a face-sharing dinuclear molecule. The Ni (II) ion is coordinated by the L (3-) ligand in a N 3O 3 coordination sphere, and the three phenolate oxygen atoms coordinate to an Ln (III) ion as bridging atoms. The Ln (III) ion is eight-coordinate, with four oxygen atoms of two hfac (-)'s, three phenolate oxygen atoms of L (3-), and one ethanol oxygen atom coordinated. Temperature-dependent magnetic susceptibility and field-dependent magnetization measurements showed a ferromagnetic interaction between Ni (II) and Gd (III) in 1.Gd. The Ni (II)-Ln (III) magnetic interactions in 1.Eu, 1.Tb, and 1.Dy were evaluated by comparing their magnetic susceptibilities with those of the isostructural Zn (II)-Ln (III) complexes, [(ZnL)Ln(hfac) 2(EtOH)] ( 2.Ln) containing a diamagnetic Zn (II) ion. A ferromagnetic interaction was indicated in 1.Tb and 1.Dy, while the interaction between Ni (II) and Eu (III) was negligible in 1.Eu. The magnetic behaviors of 1.Dy and 2.Dy were analyzed theoretically to give insight into the sublevel structures of the Dy (III) ion and its coupling with Ni (II). Frequency dependence in the ac susceptibility signals was observed in 1.Dy. PMID:18512903

Yamaguchi, Tomoka; Sunatsuki, Yukinari; Ishida, Hiroyuki; Kojima, Masaaki; Akashi, Haruo; Re, Nazzareno; Matsumoto, Naohide; Pochaba, Andrzej; Mrozi?ski, Jerzy

2008-07-01

7

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

SciTech Connect

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

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

2011-08-15

8

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

PubMed

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

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

2014-09-14

9

Nanostructure magneto-optical thin films of rare earth (RE=Gd,Tb,Dy) doped cobalt spinel by sol-gel synthesis  

Microsoft Academic Search

Nanocrystalline CoFe1.9RE0.1O4 [rare earth (RE=Gd,Tb,Dy)] films have been prepared by the sol-gel route, and their polar magneto-optical (MO) Kerr rotation and ellipticity have been determined in the spectral range of 4000-8000 Å. The films are composed of nanometer grains with the spinel structure. RE doped cobalt spinel ferrites are found to have dramatic changes in magnetic and MO properties, with

Fuxiang Cheng; Chunsheng Liao; Junfeng Kuang; Zhigang Xu; Chunhua Yan; Liangyao Chen; Haibin Zhao; Zhu Liu

1999-01-01

10

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

PubMed

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

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

2015-02-21

11

Magnetism and magnetocaloric effect in YNi4Si-type RNi4Si (R=Ce, Gd, Tb and Dy) compounds  

NASA Astrophysics Data System (ADS)

Magnetic properties and magnetocaloric effect of YNi4Si-type RNi4Si (R=Ce, Gd, Tb and Dy) compounds have been investigated. Magnetic measurements indicate the intermediate valence state of cerium in YNi4Si-type CeNi4Si. The magnetocaloric effect of GdNi4Si, TbNi4Si and DyNi4Si are calculated in terms of isothermal magnetic entropy change and they reach maximum values of -22.9 J/kg K, -13.5 J/kg K and -15.6 J/kg K for a field change of 140 kOe near ~28 K, 47 K and 27 K and they show maximum values of -12.7 J/kg K, -7.8 J/kg K and -9.3 J/kg K for a field change of 50 kOe near ~28 K, 42 K and 22 K, respectively. In contrast to GdNi4Si, the magnetization-field isotherms for TbNi4Si and DyNi4Si exhibit hysteresis loop at 2 K due to strong magnetocrystalline anisotropy.

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

2015-03-01

12

Nanostructure magneto-optical thin films of rare earth (RE=Gd,Tb,Dy) doped cobalt spinel by sol-gel synthesis  

NASA Astrophysics Data System (ADS)

Nanocrystalline CoFe1.9RE0.1O4 [rare earth (RE=Gd,Tb,Dy)] films have been prepared by the sol-gel route, and their polar magneto-optical (MO) Kerr rotation and ellipticity have been determined in the spectral range of 4000-8000 Å. The films are composed of nanometer grains with the spinel structure. RE doped cobalt spinel ferrites are found to have dramatic changes in magnetic and MO properties, with increases in their coercive force and enhancement of the MO rotation in the Tb3+ doped sample.

Cheng, Fuxiang; Liao, Chunsheng; Kuang, Junfeng; Xu, Zhigang; Yan, Chunhua; Chen, Liangyao; Zhao, Haibin; Liu, Zhu

1999-03-01

13

Superconductivity above 50 K in LnFeAsO1-y (\\textit{Ln} = Nd, Sm, Gd, Tb, and Dy) Synthesized by High-Pressure Technique  

NASA Astrophysics Data System (ADS)

We have succeeded in synthesizing single-phase polycrystalline samples of oxygen-deficient oxypnictide superconductors, LnFeAsO1-y (Ln: lanthanide elements) with \\textit{Ln} = La, Ce, Pr, Nd, Sm, Gd, Tb, and Dy using high-pressure technique. It is found out that the synthesis pressure is a key parameter for synthesizing samples, in particular for the heavier Ln’s, such as Tb and Dy. The lattice parameters systematically decrease with the atomic number of Ln, reflecting the shrinkage of Ln ionic radius. For the lighter Ln’s (La, Ce, Pr, Nd), Tc increases monotonously with decreasing the lattice parameters from 26 K for \\textit{Ln} = La to 54 K for \\textit{Ln} = Nd, then stays at the constant value around 53 K for the heavier counterpart (Nd, Sm, Gd, Tb, and Dy). The results suggest the intimate relationship between the crystal structural parameters and the superconductivity, as well as the possible existence of the inherent maximum Tc, which is located around 50 K in the LnFeAsO based materials.

Miyazawa, Kiichi; Kihou, Kunihiro; Shirage, Parasharam M.; Lee, Chul-Ho; Kito, Hijiri; Eisaki, Hiroshi; Iyo, Akira

2009-03-01

14

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, P3¯c1, 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 Birch-Murnaghan 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 H-H 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

15

Thiacalix[4]arene-supported kite-like heterometallic tetranuclear Zn(II)Ln(III)3 (Ln = Gd, Tb, Dy, Ho) complexes.  

PubMed

Four kite-like tetranuclear Zn(II)Ln(III)3 (Ln= Gd 1, Tb 2, Dy 3, Ho 4) clusters supported by p-tert-butylthiacalix[4]arene (H4BTC4A) have been prepared under solvothermal conditions and structurally characterized by single crystal X-ray diffraction and powder X-ray diffraction (PXRD). In the structures of these four complexes, each of them is capped by two tail-to-tail p-tert-butylthiacalix[4]arene molecules to form a bent sandwich-like unit. The photoluminescent analyses reveal that the H4BTC4A is an efficient sensitizer for Tb(3+) ions in 2. The magnetic properties of complexes 1-4 are also investigated, in which complex 3 exhibits slow magnetization relaxation typical for single molecule magnets. PMID:23485195

Su, Kongzhao; Jiang, Feilong; Qian, Jinjie; Wu, Mingyan; Xiong, Kecai; Gai, Yanli; Hong, Maochun

2013-04-01

16

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; Bréfuel, Nicolas; Tuchagues, Jean-Pierre; Vendier, Laure; Wernsdorfer, Wolfgang

2010-10-18

17

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

PubMed

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

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

2015-03-01

18

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

19

The Influence of R2O3 (R = Yb, Er, Dy, Tb, Gd, Sm and Ce) on the Electric and Mechanical Properties of a Nickel-Zinc Ferrite  

NASA Astrophysics Data System (ADS)

The lattice constant, density, electrical resistivity, activation energy, carrier concentration, mobility and Vickers hardness were studied on rare-earth-substituted nickel-zinc ferrites, with formula Ni0.7Zn0.3Fe1.98R0.02O4, where R = Yb, Er, Dy, Tb, Gd, Sm and Ce. We have found that all the rare-earth ions favor the occurrence of a second phase resulting in an increase of the electrical resistivity, bulk density and hardness. The log = f(1/T) curves show two regions of different activation energy. The difference between the two activation energies was explained by an important activation of the carrier mobility at higher temperatures and by a conduction mechanism sensitive to the microstructure.

Rezlescu, E.; Rezlescu, N.; Popa, P. D.; Rezlescu, L.; Pasnicu, C.

1997-08-01

20

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

SciTech Connect

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

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

2007-04-29

21

Tunnel-diode Resonator Spectroscopy of Quantum Levels in Cr12Ln4 (Ln=Y,Eu,Gd,Tb,Dy,Ho,Yb) Magnetic Molecules  

NASA Astrophysics Data System (ADS)

The differential magnetic susceptibility for a series of Cr12Ln4 (Ln=Y,Eu,Gd,Tb,Dy,Ho,Yb) magnetic molecules was measured in static (up to 16 T) and pulsed (up to 45 T) magnetic fields using a rf tunnel-diode resonator (TDR). At low temperatures, the behavior of these finite spin systems is governed by discrete energy spectra of the individual molecules. In magnetic field, low-energy quantum levels Zeeman-split, crossing at field values where magnetization exhibits a step corresponding to switching between different spin states. In high fields, we detect multiple level crossings which allow for a detailed mapping of the energy diagram. We then perform quantum Monte Carlo (QMC) using a Heisenberg Hamiltonian with three adjustable exchange constants whose values are chosen so as to optimize agreement with the experimental energy spectrum. The variations in results for the studied molecules are correlated to the magnetic properties of the lanthanide ions.

Yeninas, Steven; Luban, Marshall; Prozorov, Ruslan; Coniglio, William A.; Agosta, Charles C.; Engelhardt, Larry; Timco, Grigore A.; Winnpenny, Richard E. P.

2011-03-01

22

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

23

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

PubMed

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

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

2014-12-15

24

Ternary compounds REAgSb{sub 2}, RE = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm: Magnetism and crystal structure  

SciTech Connect

Ternary compounds REAgSb{sub 2}, RE = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, have been synthesized by arc melting followed by a heat treatment at 600 or 800{degrees}C for 300 hr. The novel phases were all found to be isotypic with the structure type of ZrCuSi{sub 2}. Precise atom parameters have been derived for CeAgSb{sub 2} from X-ray single crystal counter data: space group P4/nmm, a = 0.43641(9) nm, c = 1.0722(4) nm, and Z = 2. For 274 reflections ({vert_bar}F{sub o}{vert_bar} > 3{sigma}) the residual values are R{sub F} = {Sigma}{vert_bar}{Delta}F{vert_bar}/{Sigma}{vert_bar}F{sub o}{vert_bar} = 0.024 and R{sub w} = 0.028. A standardized set of atom parameters is provided. Magnetism of the REAgSb{sub 2} phases in the temperature range 2.5 to 300 K is characterized by tripositive paramagnetic behavior of the rare-earth atoms. REAgSb{sub 2} with RE = Y, La are weakly temperature-dependent paramagnets. In contrast, REAgSb{sub 2} compounds with RE = Pr, Nd, Sm, Gd, Dy, Ho, Er, Tm are weak antiferromagnets with ordering temperatures lower than T{sub N} {approximately} 13 K, and CeAgSb{sub 2} is a noncolinear antiferromagnet (T{sub M} {approximately} 12 K) with a remanent magnetization {mu} = 0.15 {mu}{sub B} per Ce atom.

Sologub, O.; Leithe-Jasper, A.; Rogl, P. [Institut fuer Physikalische Chemie der Universitaet Wien, Vienna (Austria)] [Institut fuer Physikalische Chemie der Universitaet Wien, Vienna (Austria); Noeel, H. [Universite de Rennes I (France)] [Universite de Rennes I (France); Bodak, O.I. [Univ. of Lviv (Ukraine)] [Univ. of Lviv (Ukraine)

1995-03-01

25

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

26

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

PubMed

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

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

2014-07-14

27

Pentanuclear heterometallic {Mn(III)(2)Ln(3)} (Ln = Gd, Dy, Tb, Ho) assemblies in an open-book type structural topology: appearance of slow relaxation of magnetization in the Dy(III) and Ho(III) analogues.  

PubMed

The reaction of Ln(III) nitrate and Mn(ClO4)2·6H2O salts in the presence of a multidentate sterically unencumbered ligand, (E)-2,2'-(2-hydroxy-3-((2-hydroxyphenylimino)methyl)-5-methylbenzylazanediyl)diethanol (LH4) leads to the isolation of four isostructural pentanuclear hetereometallic complexes [Mn(III)2Gd3(LH)4(NO3)(HOCH3)]ClO4·NO3 (1), [Mn(III)2Dy3(LH)4(NO3)(HOCH3)]ClO4·NO3 (2), [Mn(III)2Tb3(LH)4(NO3)(HOCH3)]ClO4·NO3 (3), and [Mn(III)2Ho3(LH)4(NO3)(HOCH3)]ClO4·NO3 (4) with an open-book type structural topology. 1-4 are dicationic and crystallize in the achiral space group, P21/n. A total of four triply deprotonated ligands, [LH](3-), are involved in holding the pentameric metal framework, {Mn(III)2Ln3}. In these complexes both the lanthanide and the manganese(III) ions are doubly bridged, involving phenolate or ethoxide oxygen atoms. The magnetochemical analysis reveals the presence of global antiferromagnetic interactions among the spin centers at low temperatures in all the four compounds. AC susceptibility measurements show the presence of temperature dependent out-of-phase ac signal for compounds 2 and 4 indicating an SMM behavior. PMID:24902495

Bag, Prasenjit; Chakraborty, Amit; Rogez, Guillaume; Chandrasekhar, Vadapalli

2014-07-01

28

Crystal structures, physical properties and NMR experiments on the ternary rare-earth metal silicide boride compounds RE 5Si 2B 8 ( RE=Y, Sm, Gd, Tb, Dy, Ho)  

Microsoft Academic Search

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)Å and a=7.1830(2), c=7.9900(3)Å for Sm5Si2B8 and Ho5Si2B8,

Jérome Roger; Volodymyr Babizhetskyy; Stéphane Cordier; Josef Bauer; Kurt Hiebl; Laurent Le Pollès; Sharon Elisabeth Ashbrook; Jean-François Halet; Roland Guérin

2005-01-01

29

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

30

LETTER TO THE EDITOR: Magnetic entropy change in RCoAl (R = Gd, Tb, Dy, and Ho) compounds: candidate materials for providing magnetic refrigeration in the temperature range 10 K to 100 K  

NASA Astrophysics Data System (ADS)

Large magnetic entropy changes were observed in RCoAl compounds, where R = Gd, Tb, Dy, and Ho, at their Curie temperatures. These RCoAl alloys have a hexagonal, MgZn2 structure and their Curie temperatures fall in the temperature range 10-100 K. A `table-like' behaviour was found in the temperature dependence of the magnetic entropy change (-?S(T)) obtained in the soft magnetic GdCoAl alloys, which can be used either to fill up the gap (near 100 K) in the profile of magnetic entropy change versus temperature required by an eight-stage magnetic refrigerator or to complete an Ericsson circle. It has also been shown that soft ferromagnetic materials with Curie temperatures in the temperature range from 10 K to 100 K can be obtained by using multi-R elements instead of a single-R element in the RCoAl compounds.

Zhang, X. X.; Wang, F. W.; Wen, G. H.

2001-08-01

31

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

SciTech Connect

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

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

2013-02-15

32

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

33

The effect of hybridization on local magnetic interactions at highly diluted Ce ions in tetragonal intermetallic compounds RERh2Si2 (RE=Ce, Pr, Nd, Gd, Tb, Dy).  

PubMed

The contribution of the 4f electron to the local magnetic field at highly diluted Ce atoms in RERh(2)Si(2) (RE = Ce, Pr, Nd, Gd, Tb, Dy) has been investigated as a function of temperature through the measurement of the magnetic hyperfine field in (140)Ce nuclei by time differential perturbed gamma-gamma angular correlation spectroscopy. Samples of the studied compounds were characterized by x-ray diffraction and zero-field resistance to determine the crystal structure and transport properties. DC magnetic susceptibility was measured for NdRh(2)Si(2). It was observed that the variation of the magnetic hyperfine field with temperature follows the expected behaviour for the host magnetization, with the exception of GdRh(2)Si(2), which showed a strong deviation from such a behaviour. It is shown that the hybridization of the d band of the host with the f band of the Ce impurity, which is stronger in GdRh(2)Si(2) than in other compounds, is responsible for the observed deviation from the expected temperature dependence of the hyperfine field. The origin of this stronger hybridization is ascribed to the relatively small magnetic anisotropy observed in GdRh(2)Si(2) when compared with the other compounds of the series, as shown by resistance measurements. PMID:23006536

Cabrera-Pasca, G A; Carbonari, A W; Bosch-Santos, B; Mestnik-Filho, J; Saxena, R N

2012-10-17

34

The effect of hybridization on local magnetic interactions at highly diluted Ce ions in tetragonal intermetallic compounds RERh2Si2 (RE=Ce, Pr, Nd, Gd, Tb, Dy)  

NASA Astrophysics Data System (ADS)

The contribution of the 4f electron to the local magnetic field at highly diluted Ce atoms in RERh2Si2 (RE = Ce, Pr, Nd, Gd, Tb, Dy) has been investigated as a function of temperature through the measurement of the magnetic hyperfine field in 140Ce nuclei by time differential perturbed gamma-gamma angular correlation spectroscopy. Samples of the studied compounds were characterized by x-ray diffraction and zero-field resistance to determine the crystal structure and transport properties. DC magnetic susceptibility was measured for NdRh2Si2. It was observed that the variation of the magnetic hyperfine field with temperature follows the expected behaviour for the host magnetization, with the exception of GdRh2Si2, which showed a strong deviation from such a behaviour. It is shown that the hybridization of the d band of the host with the f band of the Ce impurity, which is stronger in GdRh2Si2 than in other compounds, is responsible for the observed deviation from the expected temperature dependence of the hyperfine field. The origin of this stronger hybridization is ascribed to the relatively small magnetic anisotropy observed in GdRh2Si2 when compared with the other compounds of the series, as shown by resistance measurements.

Cabrera-Pasca, G. A.; Carbonari, A. W.; Bosch-Santos, B.; Mestnik-Filho, J.; Saxena, R. N.

2012-10-01

35

Amending the Anisotropy Barrier and Luminescence Behavior of Heterometallic Trinuclear Linear [M(II) ?Ln(III) ?M(II) ] (Ln(III) =Gd, Tb, Dy; M(II) =Mg/Zn) Complexes by Change from Divalent Paramagnetic to Diamagnetic Metal Ions.  

PubMed

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

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

2015-04-20

36

Tetranuclear hetero-metal [Co(II)2Ln(III)2] (Ln = Gd, Tb, Dy, Ho, La) complexes involving carboxylato bridges in a rare ?4-?(2):?(2) mode: synthesis, crystal structures, and magnetic properties.  

PubMed

A new family of 3d-4f heterometal 2 × 2 complexes [Co(II)2(L)2(PhCOO)2Ln(III)2(hfac)4] (1-5) (Ln = Gd (compound 1), Tb (compound 2), Dy (compound 3), Ho (compound 4), and La (compound 5)) have been synthesized in moderate yields (48-63%) following a single-pot protocol using stoichiometric amounts (1:1 mol ratio) of [Co(II)(H2L)(PhCOO)2] (H2L = N,N'-dimethyl-N,N'-bis(2-hydroxy-3,5-dimethylbenzyl)ethylenediamine) as a metalloligand and [Ln(III)(hfac)3(H2O)2] (Hhfac = hexafluoroacetylacetone) as a lanthanide precursor compound. Also reported with this series is the Zn-Dy analog [Zn(II)2(L)2(PhCOO)2Dy(III)2(hfac)4] 6 to help us in understanding the magnetic properties of these compounds. The compounds 1-6 are isostructural. Both hexafluoroacetylacetonate and benzoate play crucial roles in these structures as coligands in generating a tetranuclear core of high thermodynamic stability through a self-assembly process. The metal centers are arranged alternately at the four corners of this rhombic core, and the carboxylato oxygen atoms of each benzoate moiety bind all of the four metal centers of this core in a rare ?4-?(2):?(2) bridging mode as confirmed by X-ray crystallography. The magnetic susceptibility and magnetization data confirm a paramagnetic behavior, and no remnant magnetization exists in any of these compounds at vanishing magnetic field. The metal centers are coupled in an antiferromagnetic manner in these compounds. The [Co(II)2Dy(III)2] compound exhibits a slow magnetic relaxation below 6 K, as proven by the AC susceptibility measurements; the activation energy reads U/kB = 8.8 K (?0 = 2.0 × 10(-7) s) at BDC = 0, and U/kB = 7.8 K (?0 = 3.9 × 10(-7) s) at BDC = 0.1 T. The [Zn(II)2Dy(III)2] compound also behaves as a single-molecule magnet with U/kB = 47.9 K and ?0 = 2.75 × 10(-7) s. PMID:24437653

Abtab, Sk Md Towsif; Majee, Mithun Chandra; Maity, Manoranjan; Titiš, Ján; Bo?a, Roman; Chaudhury, Muktimoy

2014-02-01

37

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

PubMed

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

Nishimoto, Kazue; Sato, Takeru; Tamura, Ryuji

2013-06-12

38

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

PubMed

A new family of tetranuclear heterometallic assemblies, [Fe(III)2Gd2(H2L)4(?(2)-NO3)2]·2ClO4·2CH3OH·2H2O (1), [Fe(III)2Dy2(H2L)4(?(2)-NO3)2]·2ClO4·2CH3OH·2H2O (2), [Fe(III)2Tb2(H2L)4(?(2)-NO3)2]·2ClO4·2CH3OH·2H2O (3), have been synthesized employing a multi-dentate Schiff-base ligand, (E)-2,2'-(2-hydroxy-3-((2-hydroxyphenylimino)methyl)-5-methylbenzylazanediyl)-diethanol (H4L), Fe(ClO4)2·6H2O, and Ln(III) nitrate salts. These compounds have been structurally characterized by various analytical and spectroscopic techniques. The molecular structures of 1-3 have been confirmed by single crystal X-ray crystallography. All the three complexes contain two Fe(III) ions at the periphery and two Ln(III) ions in the centre. The entire assembly is held together by four doubly deprotonated [LH2](2-) ligands. All the three complexes (1-3) are dicationic in nature and possess an overall Z-type topology. Magnetic measurements reveal the presence of predominant ferromagnetic coupling for all the three compounds at low temperature. The presence of a frequency-dependent out-of-phase signal in the imaginary part of the ac susceptibility plot suggests a slow relaxation of magnetization for 3 (Fe(III)2Tb2). Furthermore, the magnetization dynamics of all the three complexes have been corroborated by Mössbauer spectroscopy. PMID:25248081

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

2014-11-21

39

Assembly of heterobimetallic Ni(II)-Ln(III) (Ln(III) = Dy(III), Tb(III), Gd(III), Ho(III), Er(III), Y(III)) complexes using a ferrocene ligand: slow relaxation of the magnetization in Dy(III), Tb(III) and Ho(III) analogues.  

PubMed

A family of dinuclear 3d-4f heterobimetallic complexes [LNi(H2O)(?-OAc)Ln(NO3)2]·CH3CN; {Ln = Dy(III) (1), Tb(III) (2), Ho(III) (3), Gd(III) (4), Er(III) (5), Y(III) (6)} have been synthesized by utilizing a ferrocene-based, dual compartmental ligand H2L. 1-6 are isostructural and crystallize in the triclinic (P1) space group. In these complexes Ni(II) is present in the inner coordination sphere of the dianionic [L](2-) ligand; Ln(III) is encapsulated in the outer coordination pocket. Ni(II) shows a 2N, 4O coordination environment in a distorted octahedral geometry, while the Ln(III) ion possesses a 9O coordination environment in a distorted tricapped trigonal prismatic geometry. ESI-MS studies suggest that the structural integrity of 1-6 is retained in solution. Electrochemical studies reveal that these complexes show a reversible one-electron response typical of the ferrocene motif along with an irreversible one-electron oxidation involving the Ni(II)/Ni(III) couple. Magnetic studies revealed the presence of ferromagnetic exchange coupling between Ni(II) and Ln(III) centers as shown by the increase of ?MT value upon cooling below 50 K for compounds 1, 2, 4 and 5. Further, dynamic magnetic susceptibility measurements (1-3) confirm the absence of an out-of-phase (?'') signal at zero dc fields. However, when these measurements were carried out at 1000 Oe dc field the ?'' signal was observed, although maxima could not be detected up to 2 K. PMID:24802265

Chakraborty, Amit; Bag, Prasenjit; Rivière, Eric; Mallah, Talal; Chandrasekhar, Vadapalli

2014-06-21

40

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

41

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

SciTech Connect

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

Ivashita, Flávio F.; Biondo, Valdecir; Bellini, Jusmar V.; Paesano, Andrea [Departamento de Física, Universidade Estadual de Maringá, Av. Colombo 5790, 87.020-900 Maringá, PR (Brazil)] [Departamento de Física, Universidade Estadual de Maringá, Av. Colombo 5790, 87.020-900 Maringá, PR (Brazil); Blanco, M. Cecilia; Fuertes, Valeria C.; Pannunzio-Miner, Elisa V. [INFIQC-CONICET, Departamento de Fisicoquímica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA Córdoba (Argentina)] [INFIQC-CONICET, Departamento de Fisicoquímica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA Córdoba (Argentina); Carbonio, Raúl E., E-mail: carbonio@fcq.unc.edu.ar [INFIQC-CONICET, Departamento de Fisicoquímica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA Córdoba (Argentina)

2012-09-15

42

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

43

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

SciTech Connect

We present a detailed angle-resolved photoemission spectroscopy (ARPES) investigation of the RTe3 family, which sets this system as an ideal"textbook" example for the formation of a nesting driven charge density wave (CDW). This family indeed exhibits the full range of phenomena that can be associated to CDWinstabilities, from the opening of large gaps on the best nested parts of Fermi surface (up to 0.4 eV), to the existence of residual metallic pockets. ARPES is the best suited technique to characterize these features, thanks to its unique ability to resolve the electronic structure in k space. An additional advantage of RTe3 is that theband structure can be very accurately described by a simple two dimensional tight-binding (TB) model, which allows one to understand and easily reproduce many characteristics of the CDW. In this paper, we first establish the main features of the electronic structure by comparing our ARPES measurements with the linear muffin-tinorbital band calculations. We use this to define the validity and limits of the TB model. We then present a complete description of the CDW properties and of their strong evolution as a function of R. Using simple models, we are able to reproduce perfectly the evolution of gaps in k space, the evolution of the CDW wave vector with R, and the shape of the residual metallic pockets. Finally, we give an estimation of the CDWinteraction parameters and find that the change in the electronic density of states n (EF), due to lattice expansion when different R ions are inserted, has the correct order of magnitude to explain the evolution of the CDW properties.

Hussain, Zahid; Brouet, Veronique; Yang, Wanli; Zhou, Xingjiang; Hussain, Zahid; Moore, R.G.; He, R.; Lu, D. H.; Shen, Z.X.; Laverock, J.; Dugdale, S.B.; Ru, N.; Fisher, R.

2008-01-16

44

(Ln = Eu, Tb, and Dy) Powders  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

45

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

46

Syntheses, structures, and magnetic properties of a family of tetranuclear hydroxido-bridged Ni(II)2Ln(III)2 (Ln = La, Gd, Tb, and Dy) complexes: display of slow magnetic relaxation by the zinc(II)-dysprosium(III) analogue.  

PubMed

A new family of [2 × 2] tetranuclear 3d-4f heterometallic complexes have been synthesized. These are [Zn(2)Dy(2)L(2)(?(3)-OH)(2)(?(4)-OH)(dbm)(2)(MeOH)(2)](NO(3))·2H(2)O·MeOH (3), [Ni(2)Dy(2)L(2)(?(3)-OH)(2)(?(4)-OH)(dbm)(2)(MeOH)(2)](NO(3))·MeOH (4), [Ni(2)La(2)L(2)(?(3)-OH)(2)(?(4)-OH)(dbm)(2)(MeOH)(2)](ClO(4))·H(2)O·2MeOH (5), [Ni(2)Tb(2)L(2)(?(3)-OH)(2)(?(4)-OH)(dbm)(2) (MeOH)(2)](NO(3))·MeOH (6), and [Ni(2)Gd(2)L(2)(?(3)-OH)(2)(?(4)-OH)(dbm)(2)(MeOH)(2)](NO(3))·MeOH (7), [H(2)L = N,N'-dimethyl-N,N'-bis(2-hydroxy-3,5-dimethylbenzyl)ethylenediamine and Hdbm = dibenzoylmethane] obtained through a single-pot synthesis using [Zn(HL)(dbm)] (for 3)/[Ni(HL)(dbm)]·2CH(3)OH (for 4, 5, 6, and 7) as 3d-metal ion precursors. Single-crystal X-ray diffraction analysis and electrospray ionization (ESI) mass spectroscopy have been used to establish their identities. Compounds are isostructural, in which the metal ions are all connected together by a bridging hydroxido ligand in a rare ?(4)-mode. In complexes 3-7, the metal ions are antiferromagnetically coupled. Taking a cue from the results of 3 and 5, precise estimations have been made for the antiferromagnetic Ni···Ni (J(Ni) = -50 cm(-1)), Ni···Gd (J(NiGd) = -4.65 cm(-1)), and Gd···Gd (J(Gd) = -0.02 cm(-1)) exchange interactions in 7, involving the gadolinium(III) ions. The Zn(II)(2)Dy(III)(2) compound 3 has shown the tail of an out-of-phase signal in alternating current (AC) susceptibility measurement, indicative of slow relaxation of magnetization. Interestingly, the Ni(II)(2)Dy(III)(2) compound 4 in which both the participating metal ions possess large single ion anisotropy, has failed to show up any slow magnetic relaxation. PMID:22994160

Abtab, Sk Md Towsif; Maity, Manoranjan; Bhattacharya, Kisholoy; Sañudo, E Carolina; Chaudhury, Muktimoy

2012-10-01

47

Magnetoelastic vibration damping properties of TbDy alloys  

NASA Technical Reports Server (NTRS)

Damping of axial and bending mode vibrations in giant magnetoelastic polycrystalline TbDy alloys was studied at cryogenic temperatures. All specimens of TbDy were arc-melted in the proper composition ratio and dropped into a chilled copper mold. Additional treatments consisted of cold plane-rolling to induce crystallographic texture and then heat-treating to relieve internal stress. Mechanical hysteretic losses were measured at various strains, frequencies, and loading configurations down to 77 K. Both as-cast and textured polycrystalline TbDy samples were tested along with an aluminum specimen for comparison. Loss factors at multiple natural vibration frequencies of the samples were measured for axial modes. Larger damping rates were measured for axial mode vibrations than for bending mode vibrations, possibly reflecting the larger specimen volume contributing to magnetoelastic damping. At LN2 temperatures TbDy materials demonstrated q > 0.05 at 0.01 Hz and q > 0.1 at higher frequencies from 0.6-1.5 kHz.

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

2002-01-01

48

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

PubMed

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

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

2013-02-20

49

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

NASA Astrophysics Data System (ADS)

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

Krishnan, Rajagopalan; Thirumalai, Jagannathan; Kathiravan, Arunkumar

2015-01-01

50

Superconducting and nonsuperconducting Ca-free single crystals of Pb[sub 2]Sr[sub 2]RCu[sub 3]O[sub 8] (R = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, and Y): Effect of cation vacancies and the metal/insulator transition  

SciTech Connect

Ca-free single crystal and polycrystalline samples of Pb[sub 2]Sr[sub 2]RCu[sub 3]O[sub 8] have been prepared by a PbO/NaCl flux growth method and a fast solid state reaction, respectively. The electronic character of the single crystals of this series can be roughly categorized into three groups: insulating (no carrier doping in the CuO[sub 2] planes) for R = La, Ce, Pr, and Nd, semiconducting for R = Sm, Eu, Gd, and Tb, and poorly metallic for R = Dy, Ho, and Y. Crystals with R = Eu to Ho are found to be superconducting with the exception of Tb. The metallic character in these crystals is likely promoted by a cation vacancy at the rare-earth sites which has been established by crystal structural and chemical analyses. The anomalous behavior of the Tb crystals may originate from a lower dopant level as inferred from the structure determination or possibly from the presence of Tb[sup 4+]. The fact that metallic behavior is observed in nonstoichiometric polycrystalline samples and not in stoichiometric ones seems consistent with the cation vacancy carrier doping mechanism. 22 refs., 7 figs., 4 tabs.

Xue, J.S.; Reedyk, M.; Greedan, J.E.; Timusk, T. (McMaster Univ., Hamilton, Ontario (Canada))

1993-02-01

51

Synthesis, structure and properties of the oxychalcogenide series A{sub 4}O{sub 4}TiSe{sub 4} (A=Sm, Gd, Tb, Dy, Ho, Er and Y)  

SciTech Connect

Seven oxyselenide materials have been synthesised with composition A{sub 4}O{sub 4}TiSe{sub 4} (A=Sm, Gd–Er, Y) via solid state reactions of A{sub 2}O{sub 3}, TiSe{sub 2} and Se at 900 °C. They are all isostructural with Gd{sub 4}O{sub 4}TiSe{sub 4}. Structures have been refined from powder X-ray diffraction data and have monoclinic C2/m symmetry with unit cell parameters of a?15.7 Å, b?3.75 Å, c?9.65 Å and ??117.5°. They contain infinite ribbons of edge-sharing A{sub 4}O and A{sub 3}TiO tetrahedra 4 units wide, which are linked by chains of TiSe{sub 4}O{sub 2} edge-sharing octahedra. Compositions A=Gd–Ho, Y are semiconductors with conductivities 1–3 Sm{sup ?1} at 300 K, with electronic band gaps of between 0.25 and 0.37 eV. Magnetic susceptibility is reported from 1.8 K to 300 K for compositions A=Gd–Ho. Rare earth moments appear to order antiferromagnetically at low temperatures with Gd and Tb showing evidence of ferromagnetism due to spin canting over a narrow temperature range close to T{sub N}. - Graphical abstract: Illustration of the A{sub 4}O{sub 4}TiSe{sub 4} crystal structure (C2/m symmetry), A{sub 4}O and A{sub 3}TiO edge sharing tetrahedral ribbons in red, chains of edge-sharing TiSe{sub 4}O{sub 2} in blue. Rare earth=green, titanium=blue, selenium=yellow, and oxygen=red. Display Omitted - Highlights: • Seven materials with A{sub 4}O{sub 4}TiSe{sub 4} (A=Sm, Gd–Er, Y) have been synthesised as bulk phases for the first time. • Materials are semiconductors and order antiferromagnetically at ?4 K. • Structure contains M{sub 4}O tetrahedral ribbons and TiSe{sub 4}O{sub 2} 1D octahedral chains.

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

2014-02-15

52

M-shell x-ray production cross sections for 19 elements in the range Z=54-92 by H/sup +/, He/sup +/ and He/sup + +/ ions from 300 keV to 40 MeV. [Xe, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb, Hf, Ta, W, Pt, Au, Hg, Pb, Bi, and U  

SciTech Connect

In this report, the measurements done over the last three decades at various laboratories are surveyed. The elements studied were Xe, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb, Hf, Ta, W, Pt, Au, Hg, Pb, Bi, and U. The projectile energies investigated range from 300 keV to 40 MeV for the protons and 250 keV to 2.5 MeV for He/sup +/ ions. Also reported are the M-shell x-ray production cross sections of some rare-earth elements recently measured at NTSU. For these measurements the energy of incident /sup 1/H/sup +/ and /sup 4/He/sup +/ ions ranged from 0.25 to 2.5 MeV. The experimental data are compared to the M-shell ionization cross section predictions of first Born approximation, i.e. the PWBA for direct ionization plus the OBK of Nikolaev for electron capture. Comparison is also made with the theory by Brandt and Lapicki that goes beyond the first Born approximation, i.e. the ECPSSR approach which accounts for the Energy loss, Coulomb deflection and Relativistic effects in the Perturbed Stationary State theory.

Mehta, R.; Duggan, J.L.; Kocur, P.M.; Lapicki, G.; McDaniel, F.D.; Price, J.L.

1983-04-01

53

Syntheses, structures, and magnetic properties of acetato- and diphenolato-bridged 3d-4f binuclear complexes [M(3-MeOsaltn)(MeOH)x(ac)Ln(hfac)2] (M = Zn(II), Cu(II), Ni(II), Co(II); Ln = La(III), Gd(III), Tb(III), Dy(III); 3-MeOsaltn = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato; ac = acetato; hfac = hexafluoroacetylacetonato; x = 0 or 1).  

PubMed

A series of 3d-4f binuclear complexes, [M(3-MeOsaltn)(MeOH)x(ac)Ln(hfac)2] (x = 0 for M = Cu(II), Zn(II); x = 1 for M = Co(II), Ni(II); Ln = Gd(III), Tb(III), Dy(III), La(III)), have been synthesized and characterized, where 3-MeOsaltn, ac, and hfac denote N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, acetato, and hexafluoroacetylacetonato, respectively. The X-ray analyses demonstrated that all the complexes have an acetato- and diphenolato-bridged M(II)-Ln(III) binuclear structure. The Cu(II)-Ln(III) and Zn(II)-Ln(III) complexes are crystallized in an isomorphous triclinic space group P1, where the Cu(II) or Zn(II) ion has square pyramidal coordination geometry with N2O2 donor atoms of 3-MeOsaltn at the equatorial coordination sites and one oxygen atom of the bridging acetato ion at the axial site. The Co(II)-Ln(III) and Ni(II)-Ln(III) complexes are crystallized in an isomorphous monoclinic space group P2(1)/c, where the Co(II) or Ni(II) ion at the high-spin state has an octahedral coordination environment with N2O2 donor atoms of 3-MeOsaltn at the equatorial sites, and one oxygen atom of the bridged acetato and a methanol oxygen atom at the two axial sites. Each Ln(III) ion for all the complexes is coordinated by four oxygen atoms of two phenolato and two methoxy oxygen atoms of "ligand-complex" M(3-MeOsaltn), four oxygen atoms of two hfac(-), and one oxygen atom of the bridging acetato ion; thus, the coordination number is nine. The temperature dependent magnetic susceptibilities from 1.9 to 300 K and the field-dependent magnetization up to 5 T at 1.9 K were measured. Due to the important orbital contributions of the Ln(III) (Tb(III), Dy(III)) and to a lesser extent the M(II) (Ni(II), Co(II)) components, the magnetic interaction between M(II) and Ln(III) ions were investigated by an empirical approach based on a comparison of the magnetic properties of the M(II)-Ln(III), Zn(II)-Ln(III), and M(II)-La(III) complexes. The differences of ?(M)T and M(H) values for the M(II)-Ln(III), Zn(II)-Ln(III) and those for the M(II)-La(III) complexes, that is, ?(T) = (?(M)T)(MLn) - (?(M)T)(ZnLn) - (?(M)T)(MLa) = J(MLn)(T) and ?(H) = M(MLn)(H) - M(ZnLn)(H) - M(MLa)(H) = J(MLn)(H), give the information of 3d-4f magnetic interaction. The magnetic interactions are ferromagnetic if M(II) = (Cu(II), Ni(II), and Co(II)) and Ln = (Gd(III), Tb(III), and Dy(III)). The magnitudes of the ferromagnetic interaction, J(MLn)(T) and J(MLn)(H), are in the order Cu(II)-Gd(III) > Cu(II)-Dy(III) > Cu(II)-Tb(III), while those are in the order of M(II)-Gd(III) ? M(II)-Tb(III) > M(II)-Dy(III) for M(II) = Ni(II) and Co(II). Alternating current (ac) susceptibility measurements demonstrated that the Ni(II)-Tb(III) and Co(II)-Tb(III) complexes showed out-of-phase signal with frequency-dependence and the Ni(II)-Dy(III) and Co(II)-Dy(III) complexes showed small frequency-dependence. The energy barrier for the spin flipping was estimated from the Arrhenius plot to be 14.9(6) and 17.0(4) K for the Ni(II)-Tb(III) and Co(II)-Tb(III) complexes, respectively, under a dc bias field of 1000 Oe. PMID:23646986

Towatari, Masaaki; Nishi, Koshiro; Fujinami, Takeshi; Matsumoto, Naohide; Sunatsuki, Yukinari; Kojima, Masaaki; Mochida, Naotaka; Ishida, Takayuki; Re, Nazzareno; Mrozinski, Jerzy

2013-05-20

54

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

55

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

56

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

SciTech Connect

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

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

2013-10-15

57

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

PubMed

Lead borate glasses doubly doped with Dy(3)(+)-Tb(3+) and Tb(3+)-Eu(3+) were investigated using optical spectroscopy. Luminescence spectra of rare earths were detected under various excitation wavelengths. The main green emission band due to (5)D4?(7)F5 transition of Tb(3+) is observed under excitation of Dy(3+), whereas the main red emission band related to (5)D0?(7)F2 transition of Eu(3+) is successfully observed under direct excitation of Tb(3+). In both cases, the energy transfer processes from Dy(3+) to Tb(3+) and from Tb(3+) to Eu(3+) in lead borate glasses occur through a nonradiative processes with efficiencies up to 16% and 18%, respectively. The presence of energy transfer process was also confirmed by excitation spectra measurements. PMID:24824577

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

2014-08-14

58

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

59

Heat treatments of Gd IIO IIS:Tb, Y IIO IIS:Tb phosphors  

NASA Astrophysics Data System (ADS)

It's well known, that some heat treatments improve significantly the light yield of Gd IIO IIS:Tb, Y II0 IIS:Tb phosphors, but processes ofthe energy transfer at excitations need further investigations. We present the new results ofthe synthesis and heat treatments optimization of oxysulfide phosphors. The heat treatments curried out at different ambient atmospheres in temperature range 200-1000°C. To measure kinetic properties of defects formations/annealing at heat treatments we measured the dependencies ofrelative defect concentrations on the duration of isothermal annealing. The investigation of bulk and surface defects in phosphors before and after heat treatments carried out at different excitation with different methods: spectra measurements with direct Tb 3+ center excitation (4.9 eV UV excitation), spectra measurements with above gap excitation (X-ray; 1 kV and 10 kV electrons, 8.4 eV VUV excitation), thermo-stimulated luminescence measurements. The results of investigations allow us to increase the light yield of phosphors (20% increase in comparison with commercial samples).

Mikhitaryan, Boris V.; Manashirov, Oshir Y.; Mikhrin, Sergey B.

2007-04-01

60

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

61

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

NASA Astrophysics Data System (ADS)

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

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

2002-03-01

62

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

E-print Network

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

Erskine, James L.

63

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

64

Trapping parameters and kinetics in Gd 2O 2S: Tb phosphor  

NASA Astrophysics Data System (ADS)

Thermoluminescence (TL) of gadolinium oxysulfide activated with Tb (Gd 2O 2S: Tb) is investigated. The TL spectrum recorded in the temperature range 93 to 500 K with a heating rate of 0.52 K s -1 shows five glow peaks. An analysis of the trapping parameters and order of kinetics for all of the prominent glow peaks has been done.

Chatterjee, S.; Shanker, V.; Ghosh, P. K.

1991-12-01

65

[Spectra of Ce3+, Tb3+ and Gd3+ Ions in Ln(BO3,PO4) [Ln = La, Y  

PubMed

Emission and excitation spectra of Ce3+, Tb3+ and Gd3+ in lanthanum borophosphate and yttrium borophosphate are studied. The results show that Ce3+ emission weakens and Tb3+ emission enhances in La(BO3, PO4):Ce, Tb in the presence of Gd, and in Y(BO3, PO4):Ce, Tb, the Ce3+ and Tb3+ emissions are all enhanced, and the former increases more than the latter. In a whole, Gd3+ acts as intermediate of energy transfer from Ce3+ to Tb3+ and sensitizer in La(BO3, PO4):Ce, Tb, Gd; while in Y(BO3, PO4):Ce, Tb, Gd, Gd3+ acts only as sensitizer, and prevents energy transfer from Ce3+ to Tb3+. Compared with Y(BO3, PO4):Ce, Tb, Gd, La(BO3, PO4):Ce, Tb, Gd, phosphor absorbs ultraviolet radiation easily, and emits green light with higher purity and intensity under 254 nm excitation, so it is more suitable for green-emitting phosphor in fluorescent lamp. PMID:12947644

Ding, S; Zhang, W; Xu, B; Wang, J

2001-06-01

66

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

67

Electroluminescence in Tb-doped Gd2O2S phosphor  

NASA Astrophysics Data System (ADS)

We report a strong ac green electroluminescence (EL) in powder layers of terbium doped gadolinium oxysulfide (Gd2O2S:Tb) with methyl methacrylate as binder. An intensity of the order of 30 nits (Cd/sq m) has been achieved. The EL emission spectra shows line emissions corresponding to 5D3 and 5D4 fluorescing levels of Tb(3+) ions. A very sharply rising B-V curve normally related to insulator-phosphor interface properties of a thin film electroluminescent device has been observed in these cells. This indicates the possibilities of barrier formation due to the localized space charge region in the absence of any prominent interfaces leading to impact excitation of Tb(3+) ions. This has further been confirmed by the excitation spectrum of Gd2O2S:Tb phosphor, which reveals Tb(3+) impurity absorption bands related to 4f8 shell transitions.

Shanker, V.; Chatterjee, S.; Ghosh, P. K.

1992-12-01

68

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

NASA Astrophysics Data System (ADS)

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

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

2015-04-01

69

Magnetic behavior and resistivity of the domain-wall junction GdFe(1000 Å)\\/TbFe\\/GdFe(500 Å)  

Microsoft Academic Search

A GdFe\\/TbFe\\/GdFe trilayer constitutes a magnetic nanostructure: the domain wall junction. With this device, we studied the propagation of 180° domain walls from one GdFe layer to the other, through a single planar defect (the thin TbFe layer) that acts as an artificial energy barrier. Before crossing the energy barrier, by thermal activation, due to the applied magnetic field, the

S. Mangin; G. Marchal; C. Bellouard; W. Wernsdorfer; B. Barbara

1998-01-01

70

Metamagnetic behaviors in RRu2Al10(R = Tb, Dy, Ho) single crystals  

NASA Astrophysics Data System (ADS)

We measured the magnetization M and the specific heat C of TbRu2Al10, DyRu2Al10 and HoRu2Al10 single crystals. We observed antiferromagnetic transitions at the temperature T = 15 K for TbRu2Al10, 6.5 and 5.1 K for DyRu2Al10 and 5.0 K for HoRu2Al10 in the temperature dependences of M divided by the applied magnetic field, M/H. The magnetization curves exhibit metamagnetic behaviors below their magnetic transitions of all materials. M of TbRu2Al10 at T = 2 K along the c-axis shows the metamagnetic behavior at H = 1.2, 1.6 and 3.2 T and shows a complex behavior with small jumps around H = 4, 5 and 6.2 T along the a-axis. As for DyRu2Al10, the metamgnetic behaviors were observed at H = 0.16, 1.35 and 1.8 T along the c-axis. In addition to the magnetic transitions at T = 5.1 and 6.5 K, we observed an unusual drop around 2 K in the temperature dependence of M/H and correspondingly a kink in the magnetic specific heat at T = 1.5 K. As for the specific heat of HoRu2Al10, an upturn due to a nuclear contribution in the specific heat was observed below 1.5 K.

Mizushima, Toshio; Watanabe, Yuuya; Ejiri, Jun-ichi; Kuwai, Tomohiko; Isikawa, Yosikazu

2015-03-01

71

Fiber optic magnetic field sensor based on the TbDyFe rod  

NASA Astrophysics Data System (ADS)

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

Chen, Feifei; Jiang, Yi

2014-08-01

72

SQUID magnetometer study of uniaxially stressed antiferromagnets DySb and GdSb  

SciTech Connect

Magnetic susceptibility experiments were performed on DySBb and the related compound GdSb under uniaxial stress. Measurements were made of the effect of compressive uniaxial stress on the transition and on the magnetic susceptibility in the antiferromagnetic and paramagnetic phases. For the experiments a new apparatus was designed and constructed combining a SQUID magnetometer with a uniaxial stress device. The magnetic moment sensitivity in low fields is 1.2 x 10/sup -8/ G cm/sup 3/ and the applied force may be measured to a sensitivity of .006 N. Measurements were made in magnetic fields less than 100 Oe and with applied uniaxial stresses of up to 400 MPa (4 Kbar). Results are presented for three single crystals of DySb. Under compressive stress the transition temperature of all three samples shifts upwards at a rate of (1.2 +/- 0.2) x 10/sup -2/ K/MPa and the discontinuity in magnetic moment at the transition is reduced. The antiferromagnet GdSb is isomorphic to DySb but has no quadrupole moment. Under uniaxial stress the transition temperature was observed to shift upwards at a rate of (6.3 +/- 0.2) x 10/sup -4/ K/MPa but no change in the paramagnetic susceptibility could be detected.

Osterman, D.P.

1986-01-01

73

Optical spectra and luminescence dynamics of the Dy-doped Gd2SiO5 single crystal  

NASA Astrophysics Data System (ADS)

Spectroscopic properties of the Dy3+:Gd2SiO5 (GSO) single crystal were investigated. The polarized absorption and unpolarized emission spectra were measured at temperature ranging from 10 K to 300 K. Experimental oscillator strengths were determined from room temperature polarized absorption spectra and phenomenological intensity parameters ? t were calculated by using the standard Judd-Ofelt theory. Low-temperature measurements were used to determine the energy level structure of two nonequivalent Dy3+ sites in the GSO crystalline host. Analysis of spectra and decay curves of the 4F9/2 emission revealed that Dy3+ ions entering nine-coordinated sites with C 3 v symmetry and Dy3+ ions entering the seven-coordinated sites with C s symmetry form two distinct, well-isolated subsystems weakly coupled by the spectral energy migration process. In addition to dissimilar crystal field splitting of multiplets, the two subsystems differ significantly in the efficiency of excitation energy transfer between dysprosium ions, thereby showing dissimilar self-quenching of the 4F9/2 emission. Besides, only one of the two Dy3+ subsystems is coupled to Gd3+ ions by nonradiative Gd3+-Dy3+ energy transfer process. Laser potential related to the 4F9/2?6H13/2 yellow luminescence of dysprosium ions was assessed based on evaluation of the emission cross-section values. It was concluded that the Dy:Gd2SiO5 (Dy:GSO) is a promising material for the visible laser operation.

Lisiecki, R.; Dominiak-Dzik, G.; Solarz, P.; Ryba-Romanowski, W.; Berkowski, M.; G?owacki, M.

2010-02-01

74

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

E-print Network

New TbFeAs(O,F) and DyFeAs(O,F) superconductors with critical temperatures T-c = 46 and 45 K and very high critical fields, >= 100 T, have been prepared at 1100-1150 degrees C and 10-12 GPa, demonstrating that high pressure may be used to synthesise...

Attfield, J.P.; Huxley A.D.; Sokolov D.A.; Rodgers J.A.; Penny G.B.S.; Bos J.W.G.

2008-01-01

75

The stress dependence of magnetostriction hysteresis in TbDyFe [110] oriented crystal  

NASA Astrophysics Data System (ADS)

The magnetostriction curves and minor loops of the TbDyFe [110] oriented crystal are tested under different compressive pre-stress from 0 to 120 MPa. It is observed that the magnetostriction hysteresis first increases from about 33 Oe under 0 MPa, achieves the maximum of about 70 Oe under 30 MPa, and then decreases to about 16 Oe under 120 MPa (near disappearance) with an increase in the compressive pre-stress. By the theoretical simulation, it is found that upon increasing the compressive pre-stress the dominant energy changes from magnetocrystalline anisotropy energy to magnetoelastic energy. This leads to the domain rotation mode changing from irreversibility to reversibility and consequently results in the decrease of magnetostriction hysteresis, which explains the experimental results very well.

Wang, Zhibin; Liu, Jinghua; Jiang, Chengbao; Xu, Huibin

2011-06-01

76

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

77

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

NASA Astrophysics Data System (ADS)

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

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

2004-12-01

78

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

SciTech Connect

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

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

2013-04-22

79

Host-sensitized luminescence properties in CaNb2O6:Ln(3+) (Ln(3+) = Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+)) phosphors with abundant colors.  

PubMed

A series of Ln(3+) (Ln(3+) = Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+)) ion doped CaNb2O6 (CNO) phosphors have been prepared via the conventional high-temperature solid-state reaction route. The X-ray diffraction (XRD) and structure refinement, diffuse reflection, photoluminescence (PL), and fluorescent decay curves were used to characterize the as-prepared samples. Under UV radiation, the CNO host present a broad emission band from about 355 to 605 nm centered around 460 nm originating from the NbO6 octahedral groups, which has spectral overlaps with the excitation of f-f transitions of Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+) in CNO:Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+) samples. They show both host emission and respective emission lines derived from the characteristic f-f transitions of activators, which present different emission colors owing to the energy transfer from the NbO6 group in the host to Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+) with increasing activator concentrations. The decreases of decay lifetimes of host emissions in CNO:Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+) demonstrate the energy transfer from the hosts to Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+). The energy transfer mechanisms in CNO:Eu(3+)/Tb(3+)/Dy(3+) phosphors have been determined to be a resonant type via dipole-dipole mechanisms. For CNO:Sm(3+), the metal-metal charge transfer transition (MMCT) might contribute to the different variations of decay lifetimes and emission intensity from CNO:Eu(3+)/Tb(3+)/Dy(3+) samples. The best quantum efficiency is 71.2% for CNO:0.01/0.02Dy(3+). The PL properties of as-prepared materials indicate the promising application in UV-pumped white-emitting lighting diodes field. PMID:25495521

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

2015-01-01

80

Phase study of the (La, Ln, Ce) sub 2 CuO sub 4 (Ln = Tb, Dy, and Ho) system  

SciTech Connect

The authors studied the formation of the (La, Ln){sub 2}CuO{sub 4} T{prime}-strucure with a small amount of Ce-doping. The results show that LaLnCuO{sub 4} has a T{prime}-structure for Ln = Tb. The addition of Ce is necessary to form the T'-structure for Ln=Dy and Ho. The authors also report the T*-structure La{sub 1.1}Dy{sub 0.9}CuO{sub 4}.

Tao, Y.K.; Sun, Y.Y.; Paredes, J.; Hor, P.H.; Chu, C.W. (Univ. of Houston, TX (USA))

1989-09-01

81

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

82

Crystal structure and magnetic properties of R5Sn4 alloys, where R is Tb, Dy, Ho, and Er  

NASA Astrophysics Data System (ADS)

Crystal structure and magnetic properties of R5Sn4 alloys with R = Tb, Dy, Ho, and Er have been studied. R5Sn4, R11Sn10, and R5Sn3 phases coexist in the annealed alloys and the content of 11:10 and 5:3 phases varies between 9 and 17 wt.%. The R5Sn4 major phase has Sm5Ge4-type orthorhombic structure with space group Pnma. Tb5Sn4 has a complex magnetic structure, spin re-orientation and ferrimagnetic-paramagnetic phase transitions occur at ˜54 and ˜84 K, respectively. For Dy5Sn4, Ho5Sn4, and Er5Sn4, the antiferromagnetic-paramagnetic phase transitions occur at about 22, 15, and 8 K, respectively. The magnetic entropy changes (-?SM) of all alloys are negative at low temperature and changes to positive at higher temperatures, which could be attributed to the change of magnetic states.

Zhong, X. C.; Zou, M.; Zhang, H.; Liu, Z. W.; Zeng, D. C.; Gschneidner, K. A.; Pecharsky, V. K.

2011-04-01

83

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

84

Magnetic Field-Assisted Piezoelectric Force Microscopy Investigation of PbTiO$_{3}$–TbDyFe Bilayered Nanocomposites  

Microsoft Academic Search

The magnetoelectric coupling in a bilayered composite consisting of a polycrystalline PbTiO and an amorphous TbDyFe layer was investigated by magnetic field-assisted piezoelectric force microscopy. Both the phase and the amplitude components of the piezoelectric signal undergo substantial changes upon applying an in-plane magnetic field, demonstrating the existence of a magnetoelectric coupling between the magnetic and electrostrictive layers. Consequently, the

Amin Yourdkhani; Ezra Garza; Luis Zaldivar; Leonard Spinu; Gabriel Caruntu

2011-01-01

85

Magnetic properties of Gd 3Fe x Ti 3 ( x=34, 33, …, 24), TbFe 11Ti and TbFe 10Ti single crystals  

Microsoft Academic Search

Crystallographic structure, domain structure and magnetic properties of ternary Gd3FexTi3 (x=34, 33, …, 24), TbFe11Ti and TbFe10Ti alloys and single crystals are investigated. It is shown that all these compounds have a ThMn12 tetragonal crystal structure. The wide homogeneous region for the ThMn12 structure detected for this group of compounds is used to explain the differences in the values of

K Skokov; A Grushishev; A Khokholkov; Yu Pastushenkov; N Pankratov; T Ivanova; S Nikitin

2004-01-01

86

Magnetic properties of Gd3FexTi3 (x=34, 33, ..., 24), TbFe11Ti and TbFe10Ti single crystals  

Microsoft Academic Search

Crystallographic structure, domain structure and magnetic properties of ternary Gd3FexTi3 (x=34, 33, ..., 24), TbFe11Ti and TbFe10Ti alloys and single crystals are investigated. It is shown that all these compounds have a ThMn12 tetragonal crystal structure. The wide homogeneous region for the ThMn12 structure detected for this group of compounds is used to explain the differences in the values of

K. Skokov; A. Grushishev; A. Khokholkov; Yu. Pastushenkov; N. Pankratov; T. Ivanova; S. Nikitin

2004-01-01

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

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

89

Performance of Gd-Tb Oxysulfide Ceramic Regenerator Material for G-M Cryocoolers  

NASA Astrophysics Data System (ADS)

Although many candidate materials have been developed and tested to increase a cooling capacity at 4 K, there are only few materials available for the 4 K regenerator materials. We have developed ceramic oxide magnetic regenerator materials, GAP = GdAlO3 and GOS = Gd2O2S. The cooling tests, using those new materials showed remarkable increases on the cooling performance at 4 K in comparison with conventional magnetic regenerator materials, HoCu2 or Er3Ni [1-6]. However, the materials are effective in the temperatures between 3 K and 5 K, but not above 6 K. Therefore, HoCu2 is still needed to provide the heat capacity from 6 K to 10 K. This paper will describe the properties of a new ceramics material, Gd-Tb oxysulfide = (GdxTb1-x)2O2S in substitution for HoCu2. This study is focused on providing a high heat capacity with a broad peak curve above 6 K. Not only the experimental results on heat capacity, but also those on the cooling test will be shown.

Numazawa, T.; Kamiya, K.; Satoh, T.; Nozawa, H.; Yanagitani, T.

2004-06-01

90

Magnetostrictive properties of amorphous and partially crystalline TbDyFe thin films  

NASA Astrophysics Data System (ADS)

A series of amorphous and partially crystalline giant magnetostrictive thin films of the composition (Tb0.3Dy0.7)39Fe61 has been prepared by dc magnetron sputtering. The sputtering conditions were the same for all samples apart from the substrate temperature TS, which varied between 330 and 510 °C. The crystalline state and the magnetic properties of the samples were investigated in relation to the substrate temperature. Films deposited at TS=330-400 °C were amorphous. Crystallization started at TS=425 °C. The magnetostrictive coefficient ?, at 4 kOe and at room temperature, increased with increasing TS from 185 to 750 ppm at Hmax. This was related also to an increase of the Curie temperature TC from 35 to 315 °C. The hysteresis loops of the amorphous samples showed coercivities lower than 10 Oe. These samples presented ??300 ppm in a field of 1000 Oe. The direction of the magnetic moments in the amorphous films changed gradually from perpendicular to parallel to the film plane with increasing TS. The samples deposited at TS?425 °C showed ?max?350-750 ppm, but the magnetostrictive curve was much broader and shifted to the value of Hc.

Speliotis, A.; Kalogirou, O.; Niarchos, D.

1997-04-01

91

The lanthanoid(III) chloride cyclo-tetrasilicates M6Cl 10[Si 4O 12] ( M=Sm, Gd-Dy): Synthesis, structure and IR investigations  

NASA Astrophysics Data System (ADS)

The chloride derivatized lanthanoid(III) cyclo-tetrasilicates of the composition M6Cl 10[Si 4O 12] ( M=Sm, Gd-Dy) crystallize monoclinically in space group C2/ m ( a=1062-1065, b=1036-1052, c=1163-1187 pm, ??103°, Z=2). They are obtained by the reaction of the sesquioxides M2O 3 (or the combination of Tb 4O 7 and Tb in 3:2-molar ratio for the terbium case), the corresponding trichlorides MCl 3, and SiO 2 (silica gel) in stoichiometric ratios with double the amount of MCl 3 as flux in evacuated silica tubes (7 d at 850 °C) as transparent, pseudo-octagonal, pillar-shaped single crystals with the colour of the respective lanthanoid trication M3+. Their crystal structure can be considered as a layered arrangement in which cationic ?2{[( M2) 5Cl 9] 6+} layers are alternatingly piled with anionic ones of the kind ?2{[( M1)Cl[Si 4O 12

Hartenbach, Ingo; Jagiella, Stefan; Schleid, Thomas

2006-08-01

92

Synthesis of Gd2O2S:Tb nanoparticles and optical characterization  

NASA Astrophysics Data System (ADS)

Terbium-doped gadolinium oxysulfide (Gd2O2S:Tb) nanoparticles were synthesized by hydrothermal precipitation of urea. On the reaction, were analyzed variables as the temperature of solutions, the reaction time and the stirring velocities as main factors in the crystal growth. WAXD TEM and FTIR analysis were used to characterize the Crystallographic phase, morphology and chemical vibrations of the materials. Moreover, the photoluminescent properties were evaluated as response at the UV light, obtaining the main emission at 544 nm produced by 5D4 --> 7F5 transition of the Tb3+ ions. Besides, we found that the host lattice and doped-ions concentration is essential to obtain a strong visible photoluminescence evaluated experimentally.

Hernández-Adame, L.; Medellín-Rodríguez, F.; Méndez-Blas, A.; Vega-Acosta, R.; Palestino, G.

2013-03-01

93

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

Microsoft Academic Search

One-dimensional GdVO4:Ln3+ (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

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

2011-01-01

94

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

Microsoft Academic Search

One-dimensional GdVO: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

Min Yu; Xue Li

2011-01-01

95

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

96

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

97

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

NASA Astrophysics Data System (ADS)

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

Zhang, Jia; Wang, Yuhua; Huang, Yan

2011-06-01

98

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

SciTech Connect

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

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

2013-06-01

99

Family of carboxylate- and nitrate-diphenoxo triply bridged dinuclear Ni(II)Ln(III) complexes (Ln = Eu, Gd, Tb, Ho, Er, Y): synthesis, experimental and theoretical magneto-structural studies, and single-molecule magnet behavior.  

PubMed

Seven acetate-diphenoxo triply bridged M(II)-Ln(III) complexes (M(II) = Ni(II) and Ln(III) = Gd, Tb, Ho, Er, and Y; M(II) = Zn(II) and Ln(III) = Ho(III) and Er(III)) of formula [M(?-L)(?-OAc)Ln(NO(3))(2)], one nitrate-diphenoxo triply bridged Ni(II)-Tb(III) complex, [Ni(?-L)(?-NO(3))Tb(NO(3))(2)]·2CH(3)OH, and two diphenoxo doubly bridged Ni(II)-Ln(III) complexes (Ln(III) = Eu, Gd) of formula [Ni(H(2)O)(?-L)Ln(NO(3))(3)]·2CH(3)OH have been prepared in one pot reaction from the compartmental ligand N,N',N"-trimethyl-N,N"-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine (H(2)L). Moreover, Ni(II)-Ln(III) complexes bearing benzoate or 9-anthracenecarboxylate bridging groups of formula [Ni(?-L)(?-BzO)Dy(NO(3))(2)] and [Ni(?-L)(?-9-An)Dy(9-An)(NO(3))(2)]·3CH(3)CN have also been successfully synthesized. In acetate-diphenoxo triply bridged complexes, the acetate bridging group forces the structure to be folded with an average hinge angle in the M(?-O(2))Ln bridging fragment of ~22°, whereas nitrate-diphenoxo doubly bridged complexes and diphenoxo-doubly bridged complexes exhibit more planar structures with hinge angles of ~13° and ~2°, respectively. All Ni(II)-Ln(III) complexes exhibit ferromagnetic interactions between Ni(II) and Ln(III) ions and, in the case of the Gd(III) complexes, the J(NiGd) coupling increases weakly but significantly with the planarity of the M-(O)(2)-Gd bridging fragment and with the increase of the Ni-O-Gd angle. Density functional theory (DFT) theoretical calculations on the Ni(II)Gd(III) complexes and model compounds support these magneto-structural correlations as well as the experimental J(NiGd) values, which were found to be ~1.38 and ~2.1 cm(-1) for the folded [Ni(?-L)(?-OAc)Gd(NO(3))(2)] and planar [Ni(H(2)O)(?-L)Gd(NO(3))(3)]·2CH(3)OH complexes, respectively. The Ni(II)Dy(III) complexes exhibit slow relaxation of the magnetization with ?/k(B) energy barriers under 1000 Oe applied magnetic fields of 9.2 and 10.1 K for [Ni(?-L)(?-BzO)Dy(NO(3))(2)] and [Ni(?-L)(?-9-An)Dy(9-An)(NO(3))(2)]·3CH(3)CN, respectively. PMID:22564020

Colacio, Enrique; Ruiz, José; Mota, Antonio J; Palacios, María A; Cremades, Eduard; Ruiz, Eliseo; White, Fraser J; Brechin, Euan K

2012-05-21

100

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

PubMed

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

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

2014-09-15

101

Continuous gamma radiation feeding high-spin isomers in 148, 149, 151, 152Dy and 147Gd  

NASA Astrophysics Data System (ADS)

The energy, multipolarity and multiplicity spectra of the continuum gamma radiation feeding high-spin isomers in 148, 149, 151, 152Dy and 147Gd have been measured at several bombarding energies. The final nuclei were selected via a delayed coincidence technique while the use of a NaI(Tl) Compton shielded crystal allowed the primary gamma-ray spectra to be generated reliably from the observed spectra. It was found that: (i) the energy of both the gamma-ray statistical cascade and the neutron cascade increases with increasing excitation energy, the latter much more rapidly than expected; (ii) the multiplicity of gamma-ray cascades, in which a statistical transition was detected, is generally lower than that of the average cascade; (iii) stretched E2 spin-correlated transitions occur above J? 39 h?in152Dy and above ˜ 50.5 h?in147Gd, indicating the onset of collectivity at these spins — in addition, a region of predominantly dipole emitting states is located below T? 44 h?in147Gd; (iv) effective moments of inertia derived from the bump edge are 50-100% larger than those deduced from the density of stretched E2 transitions in the bump; (v) in 149,151Dy the bump edge is very sharp but no multiplicity features are observed; (vi) although the four Dy isotopes were populated at approximately the same excitation energy, they display considerable differences in their continuum properties. Probable interpretations of these observations are discussed, in particular we have suggested that several of the observed effects are consistent with the possible presence of high-K collective bands above the yrast line.

Ward, D.; Andrews, H. R.; Haas, B.; Taras, P.; Rud, N.

1983-03-01

102

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

NASA Astrophysics Data System (ADS)

The magnetic and transport properties of ternary rare-earth chromium germanides RCr 0.3Ge 2 ( R= Y and Tb-Er) have been determined. X-ray and neutron diffraction studies indicate that these compounds have the CeNiSi 2-type structure (space group Cmcm) [1]. Magnetic measurements reveal the antiferromagnetic ordering below TN 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 0.3Ge 2 and DyCr 0.3Ge 2 at low temperatures the magnetic ordering can be described by two vectors k1=( 1/2 >,0,0) and k2=( 1/4,0, 1/4), and k1'=( 1/2 >,0,0) and k2'=( 1/2 >,0, 1/2 >), respectively. In HoCr 0.3Ge 2 and ErCr 0.3Ge 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 0.3Ge 2 some change in the magnetic ordering is observed at Tt=5.1 K. In temperature range from Tt to TN the magnetic ordering is given by one propagation vector k=( 1/2 >,0,0). YCr 0.3Ge 2 is a Pauli paramagnet down to 1.72 K which suggests that in the entire RCr 0.3Ge 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 Nèel temperatures.

Gil, A.; Kaczorowski, D.; Penc, B.; Hoser, A.; Szytu?a, A.

2011-02-01

103

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

NASA Astrophysics Data System (ADS)

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

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

1999-06-01

104

Magnetic and magnetocaloric properties of TbMnO3 and Tb0.67R0.33MnO3 (R=Dy, Y, and Ho) bulk powders  

NASA Astrophysics Data System (ADS)

Orthorhombically distorted perovskite rare-earth manganites with smaller rare-earth ions, such as TbMnO3, have mostly been explored for their multiferroic properties. In this work, magnetic and magnetocaloric properties in both TbMnO3 and A-site substituted Tb0.67R0.33MnO3 (R=Dy, Y, Ho) powder samples, prepared via solution route, were investigated. A weak ferromagnetic component was observed in the dc magnetic data of Dy- and Ho-substituted TbMnO3 that may be due to the change in average ionic radius at the A-site (Tb-site) as well as the larger magnetic moment of the substituting ion (~10.6 ?B for Dy3+ and Ho3+ as compared to 9.7 ?B for Tb3+). The magnetic entropy was found to decrease with the dilution of the Tb3+ ordering by the introduction of both magnetic and non-magnetic dopants at the A-site. Magnetocaloric properties of these samples were evaluated and for pure TbMnO3, a maximum relative cooling power of ~103 J/kg with 5 T applied field was observed that shows its potential for magnetic refrigeration.

Staruch, M.; Kuna, L.; McDannald, A.; Jain, M.

2015-03-01

105

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

106

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

PubMed

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

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

2014-12-01

107

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

108

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

SciTech Connect

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

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

2009-03-01

109

Magnetic properties of Gd 3Fe xTi 3 ( x=34, 33, …, 24), TbFe 11Ti and TbFe 10Ti single crystals  

NASA Astrophysics Data System (ADS)

Crystallographic structure, domain structure and magnetic properties of ternary Gd 3Fe xTi 3 ( x=34, 33, …, 24), TbFe 11Ti and TbFe 10Ti alloys and single crystals are investigated. It is shown that all these compounds have a ThMn 12 tetragonal crystal structure. The wide homogeneous region for the ThMn 12 structure detected for this group of compounds is used to explain the differences in the values of spin-reorientation temperatures of RFe 11Ti compounds found by different authors.

Skokov, K.; Grushishev, A.; Khokholkov, A.; Pastushenkov, Yu.; Pankratov, N.; Ivanova, T.; Nikitin, S.

2004-05-01

110

Patterning of Gd2(WO4)3:Ln3+ (Ln=Eu, Tb) luminescent films by microcontact printing route.  

PubMed

Gd(2)(WO(4))(3) doped with Eu(3+) or Tb(3+) thin phosphor films with dot patterns have been prepared by a combinational method of sol-gel process and microcontact printing. This process utilizes a PDMS elastomeric mold as the stamp to create heterogeneous pattern on quartz substrates firstly and then combined with a Pechini-type sol-gel process to selectively deposit the luminescent phosphors on hydrophilic regions, in which a Gd(2)(WO(4))(3):Ln(3+) (Ln=Eu, Tb) precursor solutions were employed as ink. X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) spectra, as well as low voltage cathodoluminescence (CL) spectra were carried out to characterize the obtained samples. Under ultraviolet excitation and low-voltage electron beams excitation, the Gd(2)(WO(4))(3):Eu(3+) samples exhibit a strong red emission arising from Eu(3+)(5)D(0,1,2)-(7)F(1,2) transitions, while the Gd(2)(WO(4))(3):Tb(3+) samples show the green emission coming from the characteristic emission of Tb(3+) corresponding to (5)D(4)-(7)F(6,5,4,3) transitions. The results show that the patterning of rare earth-doped phosphors through combining microcontact printing with a Pechini-type sol-gel route has potential for field emission displays (FEDs) applications. PMID:21963203

Wang, Dong; Yang, Piaoping; Cheng, Ziyong; Wang, Wenxin; Hou, Zhiyao; Dai, Yunlu; Li, Chunxia; Lin, Jun

2012-01-01

111

One-dimensional GdVO 4: Ln3+ ( Ln=Eu, Dy, Sm) nanofibers: Electrospinning preparation and luminescence properties  

NASA Astrophysics Data System (ADS)

One-dimensional GdVO 4: Ln3+ ( 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 4: Ln3+ nanofibers samples crystallize at 700 °C. SEM images indicate that the as prepared precursor fibers are smooth. After being calcined at 700 °C for 4 h, the fibers still maintain their fiberlike morphology with rough surface. TEM image further manifests that the GdVO 4: Ln3+ nanofibers consist of nanoparticles. Under ultraviolet excitation and low-voltage electron beam excitation, GdVO 4: Ln3+ phosphors showed their strong characteristic emission due to an efficient energy transfer from vanadate groups to dopants. The optimum doping concentration of Ln3+ in the GdVO 4 nanofibers also has been investigated.

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

2011-01-01

112

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

PubMed

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

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

2013-01-29

113

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

114

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

115

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

116

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

PubMed

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

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

2015-02-01

117

Resistivity and anisotropic magnetization of single crystalline RNi1-xBi2±y (R = La--Nd, Sm, Gd--Dy)  

NASA Astrophysics Data System (ADS)

We present a detailed study of RNi1-xBi2±y (R = La--Nd, Sm, Gd--Dy) single crystals by measurements of temperature dependent magnetic susceptibility, magnetization, and electrical resistivity. The isostructural compounds RTBi2 and RTSb2 are known to have widths of formation, except for T = Ag. The RNi1-xBi2±y series forms with partial Ni occupancy as well as a variable Bi occupancy. For R = Ce--Nd, Gd--Dy, the RNi1-xBi2±y compounds show local-moment-like behavior and order antiferromagnetically at low temperatures. Determination of anisotropies as well as antiferromagnetic ordering temperatures for RNi1-xBi2±y (R = Ce--Nd, Sm, Gd--Dy) have been made. Although crystalline samples from this family exhibit minority, second phase, superconductivity at low temperatures associated with Ni-Bi and Bi contamination, no evidence of bulk superconductivity has been observed.

Lin, X.; Straszheim, Warren; Bud'Ko, Sergey; Canfield, Paul

2013-03-01

118

TDPAD measurement of magnetic hyperfine field for 66Ga and 71As in ferromagnetic Gd and Tb  

NASA Astrophysics Data System (ADS)

We have measured the temperature dependence of magnetic hyperfine field for 66Ga and 71As in ferromagnetic rare earth hosts Gd and Tb using TDPAD method. High spin isomeric states: 7 - in 66Ga and 9/2 + in 71As, excited by the nuclear reactions 12C(56Fe, pn)66Ga and 12C(63Cu, 2p2n)71As were used as nuclear probes for magnetic hyperfine interaction studies. The saturation the hyperfine fields, Bhf(0) for 66Ga in Gd and Tb have been determined as: 11.4 kG in Gd and 3.5 kG respectively. The Bhf(0) values for 71As have been found to be 45 kG in Gd and 14.1 kG in Tb. The measured hyperfine field values for 66Ga and 71As, scaled by the 5d moments of the rare earth hosts, follow the systematic trend observed in 3d ferromagnets viz. Fe, Co and Ni.

Mohanta, S. K.; Davane, S. M.; Mishra, S. N.

2013-05-01

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

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

121

Luminescence of Tb3+ and Gd3+ ions in sonolysis under the conditions of a single bubble moving in aqueous solutions of TbCl3 and GdCl3  

NASA Astrophysics Data System (ADS)

Luminescence bands of Tb3+ and Gd3+ ions are detected during sonolysis in the regime of a moving single bubble in aqueous solutions of TbCl3 and GdCl3 salts with concentration 1-2 mol/L. Saturation with argon, low temperatures of solutions (-5°C), and a high concentration of salts are the factors facilitating sonoluminescence of the metal. Comparison with the characteristics of sonoluminescence of lanthanide ions studied earlier in the regimes of multibubble and single-bubble sonolysis with a stationary bubble shows that the electron excitation of metal ions in the given case is associated with translational displacements of the bubble. Our results confirm the validity of the sonochemical model of microdroplet injection, which explains the penetration of nonvolatile salts into cavitation bubbles as a result of their deformation during intense movements.

Sharipov, G. L.; Abdrakhmanov, A. M.; Gareev, B. M.

2013-02-01

122

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

123

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

NASA Astrophysics Data System (ADS)

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

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

2000-06-01

124

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

PubMed

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

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

2015-02-14

125

Low-field ac magnetic susceptibility under pressure in GdMn2 and TbMn2 intermetallics  

Microsoft Academic Search

Low-field ac magnetic susceptibility experiments under pressure up to 10 kbar have been performed on the GdMn2 and TbMn2 compounds in the temperature range of 4–300 K. The results reveal the possible coexistence of two phases below TN, one in which the magnetic moment of Mn is stable and other in which the Mn does not present any magnetic moment.

M. R. Ibarra; Z. Arnold; C. Marquina; L. Garci´a-Orza; A. del Moral

1994-01-01

126

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

NASA Astrophysics Data System (ADS)

We present single crystal AC-susceptibility and magnetisation measurements of R 2PdSi 3 compounds with R=Tb, Dy, Ho, Er, and Tm. The crystal-electric field (CEF) parameter B20 and the value of the two-ion interaction exchange integral J(Q=0) are evaluated from the anisotropy of the AC-susceptibility measurements in the paramagnetic state. In addition, the magnetic anisotropy is investigated by magnetisation measurements well below the magnetic ordering temperature. Our results yield the first parameter in the CEF Hamiltonian B20/(?) to be around -40 meV/Å 2 for R 2PdSi 3. The influence of higher order terms in the CEF Hamiltonian results in a crossing of magnetic hard and easy directions in the paramagnetic state for Dy 2PdSi 3 and Ho 2PdSi 3. The anisotropy due to the CEF is conserved in the ordered state. The observed magnetic properties turn out to be complex due to the delicate interplay of CEF effects and magnetic two-ion interactions.

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

2006-06-01

127

Microwave solid state synthesis and luminescence properties of green-emitting Gd2O2S:Tb3+ phosphor  

NASA Astrophysics Data System (ADS)

Gd2-xO2S:xTb3+ phosphors were prepared by the microwave solid state method, and its phase formation and morphologies were studied by the X-ray powder diffraction (XRD) and scanning electron microscope (SEM) techniques. The photoluminescence (PL) properties, cathodoluminescence (CL) properties and PL thermal stability of the samples were investigated, which indicated that better luminescence properties can be obtained via the microwave method compared to the conventional high temperature solid-state method. The composition-optimized Gd1.85O2S:15%Tb3+ exhibited strong green emission peaking at 546 nm upon excitation at 254 nm with the CIE coordinates of (0.238, 0.382). Different electric voltage and current dependent CL spectra investigations of Gd1.85O2S:15%Tb3+ phosphor shows similar green spectral profile as PL emission and it also demonstrates the good luminescence stability suggesting its potential application as green emission component in cathode ray tube (CRT).

He, Can; Xia, Zhiguo; Liu, Quanlin

2015-04-01

128

Measurement of the response of Gd2O2S:Tb phosphor to 6 MV x-rays.  

PubMed

The phosphor GdO2S:Tb is widely used in camera-based electronic portal imaging devices (EPIDs). There is considerable interest in the application of EPIDs to dosimetry and the verification of intensity modulated radiation therapy produced by dynamic multileaf collimation (DMLC). This paper presents direct measurement of Gd2O2S:Tb phosphor luminescence under 6 MV x-ray irradiation from a linear accelerator using a photomultiplier tube. The luminescence following each radiation pulse (3 micros duration) was observed to decay with a dominant lifetime of 558 micros. Using a specialized electrometer, the temporal variation of the optical signal has been compared with the dose rate incident on the phosphor measured using a semiconductor diode detector. Under dose rates typical of those used in the clinic (1.2 Gy min(-1) to the phosphor), measurements at beam-start confirmed that the optical signal is linear with dose per radiation pulse. Measurements at beam termination following phosphor doses up to 4.4 Gy showed no residual signal associated with long-lived luminescence (afterglow) from the phosphor above the noise level of the optical signal (0.17% standard deviation). This measurement demonstrates that afterglow from Gd2O2S:Tb is not of significance for its application to DMLC verification. Additionally, it was confirmed that the accelerator pulse repetition frequency has no effect on the optical signal from the phosphor in the range 25-400 Hz. PMID:11229730

Glendinning, A G; Hunt, S G; Bonnett, D E

2001-02-01

129

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

PubMed

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

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

2014-04-21

130

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

131

Heterometallic cubane-like {M2Ln2} (M = Ni, Zn; Ln =, Gd, Dy) and {Ni2Y2} aggregates. Synthesis, structures and magnetic properties.  

PubMed

The syntheses, structural determinations and magnetic studies of tetranuclear M(II)Ln(III) complexes (M = Ni, Zn; Ln = Y, Gd, Dy) involving an in situ compartmentalized schiff base ligand HL derived from the condensation of o-vanillin and 2-hydrazinopyridine as main ligand are described. Single-crystal X-ray diffraction reveals that all complexes are closely isostructural, with the central core composed of distorted {M(2)Ln(2)O(4)} cubes of the formulas [Ni(2)Ln(2)(?(3)-OH)(2)(L)(2)(OAc)(4)(H(2)O)(3.5)](ClO(4))(2)·3H(2)O (Ln = Y 1 and Gd 2), [Ni(2)Dy(2)(?(3)-OH)(2)(L)(2)(OAc)(5)(EtOH)(H(2)O)(1.5)](ClO(4))·EtOH·H(2)O (3) and [Zn(2)Ln(2)(?(3)-OH)(2)(L)(2)(OAc)(5)(EtOH)(H(2)O)](ClO(4))·2EtOH·1.5H(2)O (Gd 4 and Dy 5). The Ln(III) ions are linked by two hydroxo bridges and each M(II) ion is also involved in a double phenoxo-hydroxo bridge with the two Ln(III) ions, so that each hydroxo group is triply linked to the two Ln(III) and one M(II) ions. The magnetic properties of all complexes have been investigated. Ni(2)Y(2) (1) has a ferromagnetic Ni(II)Ni(II) interaction. A weak ferromagnetic Ni(II)Ln(III) interaction is observed in the Ni(2)Ln(2) complexes (Ln = Gd 2, Dy 3), along with a weak antiferromagnetic Ln(III)Ln(III) interaction, a D zero-field splitting term for the nickel ion and a ferromagnetic Ni(II)Ni(II) interaction. The isomorphous Zn(2)Ln(2) (Ln = Gd 4, Dy 5) does confirm the presence of a weak antiferromagnetic Ln(III)Ln(III) interaction. The Ni(2)Dy(2) complex (3) does not behave as a SMM, which could result from a subtractive combination of the Dy and Ni anisotropies and an increased transverse anisotropy, leading to large tunnel splittings and quantum tunneling of magnetization. On the other hand, Zn(2)Dy(2) (5) exhibits a possible SMM behavior, where its slow relaxation of magnetization is probably attributed to the presence of the anisotropic Dy(III) ions. PMID:22187722

Meng, Zhao-Sha; Guo, Fu-Sheng; Liu, Jun-Liang; Leng, Ji-Dong; Tong, Ming-Liang

2012-02-28

132

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

133

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

PubMed

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

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

2012-10-15

134

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

PubMed

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

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

2014-10-21

135

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

136

Crystal Structures of Ca-Free Pb 2Sr 2RCu 3O 8 ( R = La, Pr, Nd, Eu, Tb, and Dy) Single Crystals  

NASA Astrophysics Data System (ADS)

Structures of Pb 2Sr 2RCu 3O 8 have been determined by single crystal X-ray diffraction. A monoclinic symmetry ( C2/ m, Z = 2) was found for those crystals with R = Pr, Nd, and Tb, orthorhombic ( Cmmm, Z = 2) for R = La, and tetragonal ( P4/ mmm, Z = 1) for R = Eu and Dy. The relationship among different crystal symmetries can be understood in terms of different oxygen orderings in the PbO layers driven by the Ph 2+ lone pair orientation. There is evidence for a ˜ 9% deficiency in electron density at the R = Eu and Dy sites (and ˜ 4.5% for R = Tb) which has been confirmed by mass spectroscopy as being due to cation vacancies at these sites. Bond valence sum calculations have been performed to evaluate the strains existing in the crystal structures of Pb 2Sr 2RCu 3O 8.

Xue, J. S.; Greedan, J. E.; Maric, M.

1993-02-01

137

Effect of Ce 3+, Dy 3+, and Tb 3+ additions on the spectroscopic properties of Er 3+/Yb 3+ codoped tellurite glasses  

NASA Astrophysics Data System (ADS)

Serious up-conversion process (UCPE) of Er 3+ in Er 3+/Yb 3+ codoped tellurite glass is one of the big challenges impeding Er 3+ doped tellurite fiber amplifier towards full commercialization, though its gain bandwidth is much wider than Er 3+ doped silica fiber amplifier. For solving or suppressing UCPE, it has been proposed to better introduce a third foreign ion with proper layout of energy level into this system, and thus, modulate energy transfer between them. Three rare earth ions, RE 3+=Ce 3+, Dy 3+, and Tb 3+, are selected in this paper, and it turns out that three of them can efficiently reduce the transition probability of UCPE, and Ce 3+ rather than Dy 3+ and Tb 3+ can at the same time enhance the 1.53 ?m emission of Er 3+ originating 4I 13/2? 4I 15/2. The underlying mechanism will be discussed based on both experimental and theoretical results.

Chen, D. D.; Qian, Q.; Peng, M. Y.; Xu, S. H.; Yang, Z. M.; Zhang, Q. Y.; Jiang, Z. H.

2010-11-01

138

Photoelectron spectra of the late rare-earth misfit layer compounds (LnS)1 + x TS2 (Ln = Tb, Dy, Ho; T = Nb, Ta)  

Microsoft Academic Search

Photoemission spectra (XPS and UPS) are presented for the valence band of misfit layer compounds (LnS)1 + xTS2 with Ln = Dy, Ho or Tb; T = Nb or Ta. The Nb 4dz2 (or Ta 5dz2) conduction band is almost filled, which indicates a charge transfer of slightly less than one electron per T from the LnS to the TS2

C. M. Fang; G. A. Wiegers; C. Haas

1997-01-01

139

Photoelectron spectra of the late rare-earth misfit layer compounds (LnS) 1+ x TS 2 (Ln = Tb, Dy, Ho; T = Nb, Ta)  

Microsoft Academic Search

Photoemission spectra (XPS and UPS) are presented for the valence band of misfit layer compounds (LnS)1+xTS2 with Ln = Dy, Ho or Tb; T = Nb or Ta. The Nb 4dz2 (or Ta 5dz2) conduction band is almost filled, which indicates a charge transfer of slightly less than one electron per T from the LnS to the TS2 layers. The

C. M. Fang; G. A. Wiegers; C. Haas

1997-01-01

140

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

141

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

NASA Astrophysics Data System (ADS)

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 TC ?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 ?eff. = 10.3 ?B/Dy-atom (close to theoretical value of 10.64 ?B for the free ion Dy3+) and a positive paramagnetic Curie temperature ?p = 58 K. Ni atoms are most likely to be nonmagnetic. The heat capacity also shows three peaks: a large one at 103 K 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 5 K.

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

2012-04-01

142

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

143

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

NASA Astrophysics Data System (ADS)

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

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

2009-01-01

144

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

NASA Astrophysics Data System (ADS)

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

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

1985-04-01

145

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

146

Field-induced internal Fe and Ln spin reorientation in butterfly {Fe3LnO2} (Ln = Dy and Gd) single-molecule magnets  

NASA Astrophysics Data System (ADS)

The intramolecular exchange interactions within the single-molecule magnet (SMM) “butterfly” molecule [Fe3Ln(?3-O)2(CCl3COO)8(H2O)(THF)3], where Ln(III) represents a lanthanide cation, are determined in a combined experimental [x-ray magnetic circular dichroism (XMCD) and vibrating sample magnetometer (VSM)] and theoretical work. Compounds with Ln=Gd and Dy, which represent extreme cases where the rare earth presents single-ion isotropic and uniaxial anisotropy, on one hand, and with Ln=Lu and Y(III) as pseudolanthanide substitutions that supply a nonmagnetic Ln reference case, on the other hand, are studied. The Dy single-ion uniaxial anisotropy is estimated from ab initio calculations. Low-temperature (T?2.5 K) hard x-ray XMCD at the Ln L2,3 edges and VSM measurements as a function of the field indicate that the Ln moment dominates the polarization of the molecule by the applied field. Within the {Fe3LnO2} cluster the Ln-Fe3 subcluster interaction is determined to be antiferromagnetic in both Dy and Gd compounds, with values JDy-Fe3=-0.4 K and JGd-Fe3=-0.25 K, by fitting to spin Hamiltonian simulations that consider the competing effects of intracluster interactions and the external applied magnetic field. In the uniaxial anisotropic {Fe3DyO2} case, a field-induced reorientation of the Fe3 and Dy spins from an antiparallel to a parallel orientation takes place at a threshold field (?0H=4 T). In contrast, in isotropic {Fe3GdO2} this reorientation does not occur.

Badía-Romano, L.; Bartolomé, F.; Bartolomé, J.; Luzón, J.; Prodius, D.; Turta, C.; Mereacre, V.; Wilhelm, F.; Rogalev, A.

2013-05-01

147

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

148

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

SciTech Connect

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

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

2013-02-15

149

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

PubMed

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

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

2014-01-01

150

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

151

The effects of added foreign ions in Gd 2O 2S : Tb 3+; crystal field calculations, lifetimes, photo-luminescence and absorption spectra  

Microsoft Academic Search

A spectroscopic study is carried out in which the effects of added Ca2+ and Ru4+ transition metal ions on some characteristics of the emission of Gd2O2S:Tb3+ phosphors (energy levels, intensities, lifetimes) are examined and compared. In order to distinguish the Tb3+ emissions from impurity ones, the electronic energy levels of trivalent terbium are determined and the energy level scheme is

Michèle D. Faucher; Romano Morlotti; O. K. Moune

2002-01-01

152

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

SciTech Connect

The half-lives of the isomers {sup 161m1}Dy and {sup 161m2}Dy (E = 25.6 keV and T{sub 1/2} {approx} 30 ns for the former and E = 74.6 keV and T{sub 1/2} {approx} 3 ns for the latter) placed in a {sup 160}Gd{sub 2}O{sub 3} crystal lattice at T = 300 K and surrounded by stable {sup 161}Dy nuclei in the composition of {sup 161}Dy{sub 2}O{sub 3} were measured by the method of ({beta}-{gamma}) coincidences in the beta-decay process {sup 161}Tb {yields} {sup 161}Dy. Nuclei of {sup 161m1,m2}Dy were obtained according to the chain {sup 160}Gd(n, {gamma}){sup 161}Gd {yields} {sup 161}Tb {yields} {sup 161}Dy from {sup 160}Dy{sub 2}O{sub 3} weighted portions irradiated at the PWR-M reactor of the Petersburg Nuclear Physics Institute (PNPI, Gatchina, Russia). The T{sub 1/2} value observed for the isomer {sup 161m1}Dy was found to be correlated with the number of surrounding {sup 161}Dy nuclei. The presence of this correlation in {sup 161m1}Dy can be explained by the multiple resonance scattering of photons from isomer decay within the sample used. No such correlation was observed for {sup 161m2}Dy. The half-lives measured for the isomers {sup 161m1}Dy and {sup 161m2}Dy in the absence of the above environment are 29.2(1) and 3.50(1) ns, respectively.

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

2013-06-15

153

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

154

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

155

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

SciTech Connect

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

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

2013-12-15

156

Influence of rare earth elements (Y, Gd and Lu) on the luminescent properties of green phosphor ZnMoO4:Tb3+.  

PubMed

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

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

2014-11-01

157

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

SciTech Connect

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

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

2012-06-15

158

Characterization, electrical transport and magnetic properties of the rare earth misfit layer compounds (TbS) 1.21NbS 2, (TbS) 1.20TaS 2, (DyS) 1.22NbS 2 and (DyS) 1.21TaS 2  

Microsoft Academic Search

X-ray powder and single-crystal X-ray diffraction of the title compounds showed that they are planar intergrowth compounds, built of alternating sandwiches TS2 (T ? Nb, Ta) and double layers LnS (Ln ? Tb, Dy), present in three orientational variants related by rotations of 120° around the c axis perpendicular to the layers. The TS2 and LnS subsystems are incommensurate along

W. Y. Zhou; A. Meetsma; J. L. de Boer; G. A. Wiegers

1996-01-01

159

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

SciTech Connect

A significant practical application for nanostructured materials is X-ray medical imagery, because it is necessary to use dense materials in order to enable absorption of high energy photons. An important requirement of these materials is UV-vis range emission produced by X-ray excitation, which can be influenced by the particle size. Europium doped gadolinium oxide is a well known red phosphor. Moreover, nanophosphors of Gd{sub 2}O{sub 3} codoped with Tb{sup 3+}, Eu{sup 3+} increase their light yield by energy transfer between Tb{sup 3+} and Eu{sup 3+}. In this study, Gd{sub 2}O{sub 3} nanopowders codoped with Eu{sup 3+} and Tb{sup 3+} (2.5 at.% Eu{sup 3+}, and 0.005 and 0.01 at.% Tb{sup 3+}) were obtained via a sol-gel process using gadolinium pentanedionate as precursor and europium and terbium nitrates as doping sources. In this paper, we report the influence of annealing temperature on the structure, morphology and luminescent properties of Gd{sub 2}O{sub 3}:Eu{sup 3+}, Tb{sup 3+} by means of TGA, XRD, TEM and X-ray emission measurements.

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

2010-01-15

160

Synthesis of a New Cubic Conductive Cu6O8-yMX (M=Tb, Dy, Ho, Er, Tm, Yb, Lu, X=NO3, Cl) Family  

NASA Astrophysics Data System (ADS)

A new cubic Cu6O8-yMX family (M=Tb, Dy, Ho, Er, Tm, Yb, Lu, X=NO3, Cl) was prepared. These compounds showed metallic resistivity and paramagnetism. The Cu6O8-yMX compounds could be easily synthesized when a trivalent metal element (M) whose oxide (M2O3) has a cubic Tl2O3-type structure was used. These compounds were prepared in the thermal decomposition process of a mixed copper nitrate, copper chloride and metal element oxide solution. The lattice constants of the Cu6O8-yMX compounds were related to those of M2O3.

Sugise, Ryoji; Ohdan, Kyoji; Hamamoto, Toshikazu; Kashiwagi, Kouichi; Shirai, Masashi; Yazawa, Ichiro; Ihara, Hideo

1993-07-01

161

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

162

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, Stéphane; Ledoux, Gilles; Tillement, Olivier; Perriat, Pascal

2009-05-15

163

Structural and optical properties of Tb-doped Na-Gd metaphosphate glasses and glass-ceramics  

NASA Astrophysics Data System (ADS)

The optical and structural properties of terbium doped sodium gadolinium phosphate glasses of three different compositions subjected to a crystallization process were studied and compared with those of the parent glassy samples. The structural characteristics of the glassy and crystallized phases were determined by Raman spectroscopy and the results showed a remarkable reduction in the full width at half maximum of the Raman peaks after crystallization. Radio-luminescence measurements revealed the emissions of both Gd3+ and Tb3+ ions. Their intensities strongly increased and their intensity ratio was modified by the crystallization. The luminescence temperature dependence investigated by radio-luminescence measurements in the temperature interval from 10 to 310 K became more complicated after crystallization. The role of free carrier trapping phenomena in the modification of the radio-luminescence efficiency was also studied by thermally stimulated luminescence.

Moretti, F.; Vedda, A.; Nikl, M.; Nitsch, K.

2009-04-01

164

Structural and optical properties of Tb-doped Na-Gd metaphosphate glasses and glass-ceramics.  

PubMed

The optical and structural properties of terbium doped sodium gadolinium phosphate glasses of three different compositions subjected to a crystallization process were studied and compared with those of the parent glassy samples. The structural characteristics of the glassy and crystallized phases were determined by Raman spectroscopy and the results showed a remarkable reduction in the full width at half maximum of the Raman peaks after crystallization. Radio-luminescence measurements revealed the emissions of both Gd(3+) and Tb(3+) ions. Their intensities strongly increased and their intensity ratio was modified by the crystallization. The luminescence temperature dependence investigated by radio-luminescence measurements in the temperature interval from 10 to 310 K became more complicated after crystallization. The role of free carrier trapping phenomena in the modification of the radio-luminescence efficiency was also studied by thermally stimulated luminescence. PMID:21825356

Moretti, F; Vedda, A; Nikl, M; Nitsch, K

2009-04-15

165

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

166

Decay of 152Tb and E0 and M1+E0 transitions in 152Gd  

NASA Astrophysics Data System (ADS)

The decay of 152 Tb has been investigated by means of measurements of singles ?-spectra and ?—gamma coincidence experiment. The 704 transitions were observed, of which 347 were identified to the decay of 152 Tb for the first time. Using the more precise and full data about intensities of gamma-transitions and previously reported conversion electron intensities of the E0 or M1+E0 multipolarities were established for several transitions. The revised decay scheme consists of about one hundred excited levels from which 46 levels were introduced for the first time.

Adam, J.; Pronskikh, V. S.; ?aloun, P.; Honusek, M.; Kalinnikov, V. G.; Lebedev, N. A.; Stegailov, V. I.; Tsoupko-Sitnikov, V. M.

1999-02-01

167

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

PubMed

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

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

2014-12-10

168

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

169

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

NASA Astrophysics Data System (ADS)

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

Jiménez, E.; Isasi, J.; Sáez-Puche, R.

2002-03-01

170

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

171

Low-temperature specific heat of orthorhombic and tetragonal phases of Ba2( RE) Cu3O7- ? ( RE= Gd, Dy, Ho, ErandTm)  

NASA Astrophysics Data System (ADS)

From the specific heat measurements on the superconducting (orthorhombic) and the non-superconducting (tetragonal) phases of Ba 2(RE)Cu 3O 7-?, we found a magnetic ordering for RE=Gd, Dy and Er, and no long-range ordering for RE=Ho and Tm in the temperature range studied (0.4-6.0 K). The orthorhombic phase of the former group revealed a phase transition of two-dimensional Ising type, while the tetragonal phase of Dy and Er compounds are of two-dimensional XY-type. However the difference in ordering temperature of these two phases is very small. This point is briefly discussed in relation to the superconductivity in these oxides.

Nakazawa, Y.; Ishikawa, M.; Takabatake, T.

1987-12-01

172

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

173

The extended chain compounds Ln12(C 2) 3I 17 ( 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, LnI 3 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(C 2) 3I 17-type compounds ( C 2/ c, a=19.610(1) and 19.574(4) Å, b=12.406(2) and 12.393(3) Å, c=19.062(5) and 19.003(5) Å, ?=90.45(3)° and 90.41(3)°, for Pr 12(C 2) 3I 17 and Nd 12(C 2) 3I 17, respectively). All compounds contain infinite zigzag chains of C 2-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 Gd 12(C 2) 3I 17 sample exhibits semiconducting thermal behavior which is consistent with an ionic formulation ( Ln3+) 12(C 26-) 3(I -) 17(e -) under the assumption that one extra electron is localized in metal-metal bonding. The magnetization measurements on Nd 12(C 2) 3I 17, Gd 12(C 2) 3I 17 and Dy 12(C 2) 3I 17 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 Dy 12(C 2) 3I 17, a metamagnetic transition is observed at a critical magnetic field H?25 kOe.

Ryazanov, Mikhail; Mattausch, Hansjürgen; Simon, Arndt

2007-04-01

174

New Layered Compounds with the General Composition (MO) (CuSe), Where M = Bi, Nd, Gd, Dy, and BiOCuS: Syntheses and Crystal Structure  

NASA Astrophysics Data System (ADS)

The syntheses of four new copper oxyselenides with the general formula (MO)(CuSe) ( M = Bi, Nd, Gd, Dy) and one copper oxysulfide, BiOCuS, are reported. The tetragonal unit cell dimensions of all compounds are given. A new bismuth-copper oxyselenide, BiOCuSe, has been structurally characterized from powder X-ray diffraction data and finally solved by the Rietveld profile method with RI = 0.069. The BiCuSeO crystal structure is formed by alternating [Bi 2O 2] and [Cu 2Se 2] layers.

Kusainova, A. M.; Berdonosov, P. S.; Akselrud, L. G.; Kholodkovskaya, L. N.; Dolgikh, V. A.; Popovkin, B. A.

1994-09-01

175

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

176

Electrical properties of new type high oxide ionic conductor RE 10Si 6O 27 (RE = La, Pr, Nd, Sm, Gd, Dy)  

Microsoft Academic Search

Electrical properties of the high oxide ionic conductive ceramic RE10Si6O27 (RE=La, Pr, Nd, Sm, Gd, Dy) sintered at 1700–1800 °C by the use of MgO-stabilized zirconia setter during a sintering have been investigated. The lowest activation energy and the highest conductivity at 200 °C were achieved for Pr10Si6O27 (55.4 kJmol?1) and La10Si6O27 (1.32 × 10?5 S cm?1), respectively. The conductivity

Susumu Nakayama; Masatomi Sakamoto

1998-01-01

177

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

PubMed Central

Studies concerning synthesis, structure and luminescence of eight-coordinate Eu, Tb, Sm and Dy complexes of the type [Ln(acac)2(L)]Cl (Hacac = pentanedione-2,4 and L = bis(5-(pyridine-2-yl)-1,2,4-triazol-3-yl)propane) are reported in detail. The obtained complexes were investigated by various means including elemental- and thermogravimetric analysis, IR- and electron transition spectroscopy. The structure of the Tb complex was determined by single-crystal X-ray crystallography: Tb is eight-coordinate, and L acting only as a tetradentate chelate together with two bidentate acac ligands. Photophysical studies of the complexes were carried out. The Tb(III) and Eu(III) complexes show strong emissions both in solid state and solution. The intensity of the luminescence of Dy(III) and Sm(III) are relatively weak. The factors determining the intensity of the photoluminescence are discussed. PMID:24068839

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

2013-01-01

178

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

179

Single-component and warm-white-emitting phosphor NaGd(WO4)2:Tm3+, Dy3+, Eu3+: synthesis, luminescence, energy transfer, and tunable color.  

PubMed

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

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

2014-11-01

180

Photoluminescence properties of rare earths (Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+} and Tm{sup 3+}) activated NaInW{sub 2}O{sub 8} wolframite host lattice  

SciTech Connect

The photoluminescence (PL) studies on NaIn{sub 1-x}RE{sub x}W{sub 2}O{sub 8}, with RE=Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+} and Tm{sup 3+} phases have shown that the relative contribution of the host lattice and of the intra-f-f emission of the activators to the PL varies with the nature of the rare earth cation. In the case of Dy{sup 3+} and Tm{sup 3+} activators, with yellow and blue emission, respectively, the energy transfer from host to the activator plays a major role. In contrast for Eu{sup 3+}, with intense red emission, the host absorption is less pronounced and the intra-f-f transitions of the Eu{sup 3+} ions play a major role, whereas for Tb{sup 3+} intra-f-f transitions are only observed, giving rise to green emission. - Graphical abstract: NaInW{sub 2}O{sub 8} double tungstate doped with Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+}and Tm{sup 3+} shows characteristic emission of intense red for Eu{sup 3+}, yellow for Dy{sup 3+}, green for Tb{sup 3+} and blue for Tm{sup 3+}. Highlights: Black-Right-Pointing-Pointer Characteristic emissions of rare earths (Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+} and Tm{sup 3+}) are observed NaInW{sub 2}O{sub 8} wolframite. Black-Right-Pointing-Pointer Energy transfer from host to the activators (Eu{sup 3+} Dy{sup 3+} Tm{sup 3+} is observed. Black-Right-Pointing-Pointer PL properties of rare earth ions depend on minor structural variations in the host lattice.

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

2012-01-15

181

Synthesis, luminescence, and energy-transfer properties of ?-Na2Ca4(PO4)2(SiO4):A (A = Eu(2+), Dy(3+), Ce(3+)/Tb(3+)) phosphors.  

PubMed

A series of ?-Na2Ca4(PO4)2(SiO4) (?-NCPS):A (A = Eu(2+), Dy(3+), Ce(3+)/Tb(3+)) phosphors were prepared via a high-temperature solid-state reaction route. The X-ray diffraction, Fourier transform infrared, photoluminescence (PL), cathodoluminescence (CL) properties, fluorescent lifetimes, and absolute quantum yield were exploited to characterize the samples. Under UV radiation, the ?-NCPS:Eu(2+) phosphors present bright green emissions, and the ?-NCPS:Ce(3+) phosphors show strong blue emissions, which are attributed to their 4f(6)5d(1) ? 4f(7) and 5d-4f allowed transitions, respectively. The ?-NCPS:Ce(3+), Tb(3+) phosphors display intense tunable color from blue to green and high absolute quantum yields (81% for ?-NCPS:0.12Ce(3+) and 83% for ?-NCPS:0.12Ce(3+), 0.08Tb(3+)) when excited at 365 nm. Simultaneously, the energy transfer from Ce(3+) to Tb(3+) ions is deduced from the spectral overlap between Ce(3+) emission and Tb(3+) excitation spectra and demonstrated by the change of emission spectra and decay lifetimes. Moreover, the energy-transfer mechanism from Ce(3+) to Tb(3+) ions is confirmed to be exchange interaction according to the discussion of expression from Dexter and Reisfeld. Under a low-voltage electron-beam excitation, the ?-NCPS:A (A = Eu(2+), Dy(3+), Ce(3+)/Tb(3+)) phosphors exhibit their characteristic emissions, and the emission profiles of ?-NCPS:Ce(3+),Tb(3+) phosphors are obviously different from those of the PL spectra; this difference might be ascribed to their different luminescence mechanisms. These results in PL and CL properties suggest that ?-NCPS:A (A = Eu(2+), Dy(3+), Ce(3+)/Tb(3+)) phosphors are potential candidates for solid-state lighting and field-emission displays. PMID:24905817

Li, Kai; Shang, Mengmeng; Geng, Dongling; Lian, Hongzhou; Zhang, Yang; Fan, Jian; Lin, Jun

2014-07-01

182

Luminescence Properties and Antibacterial Activity of [Ln2(NNA)6(Phen)2]· nC3H7NO (Ln = Y, Eu, Gd, Pr, Sm, Tb, Yb, n = 0, 1, 2, NAA = 1-Naphthylacetic Acid, Phen = 1, 10-Phenanthroline)  

Microsoft Academic Search

Rare earth binuclear complexes, [Ln(NAA)3(phen)]2 nDMF (NAA = 1-naphthylacetic acid, phen = 1, 10-phenanthroline, Ln = Y, Eu, Gd, Pr, Sm, Tb, Yb, DMF = N,N?-dimethylformamide), have been prepared and have been characterized by elemental analysis, infrared spectra, electronic spectra, and X-ray crystallography. All complexes crystallize in the monoclinic system, space group P21\\/c(Eu, Gd, Sm, Tb, Y) and triclinic system,

Yu-Fen Liu; De-Fu Rong; Hai-Tao Xia; Da-Qi Wang; Ya-Ming Liu

2008-01-01

183

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

184

Systematic studies of the structures and magnetic properties for a family of cubane complexes with the formula: [M2Ln2] (Ln = Dy, Gd; M = Ni, Zn) and [Ni2Y2].  

PubMed

Studies of magnetic properties of a family of tetranuclear M(II)(2)Ln(III)(2) (M = Ni, Zn; Ln = Dy, Gd and Y) complexes with hmp (anion of 2-hydroxymethylpyridine) and benzoate as ligands are reported. In these complexes, metal ions (M or Ln) occupy the four alternative corners of a distorted cubane with oxygen atoms from alkoxyl groups on the others. Complexes 1, 2 and 3 crystallized in P2(1)/c and complexes 4 and 5 in C2/c space groups. Although in different space groups, complexes 1-5 have very similar structures which permit the magnetic interactions to be systematically compared with respect to metal ion pairs. In complex 3 (Ni(2)Y(2)), clear ferromagnetic coupling between Ni(II) ions can be seen, with: g = 2.16, S = 2, D = -0.95 cm(-1), J = +3.77 cm(-1) (or g = 2.20, S = 2, D = +1.51 cm(-1)). In complex 5 (Zn(2)Gd(2)), a very weak antiferromagnetic coupling between the Gd(III) ions was observed: g = 2.08, J = -0.05 cm(-1). Based on these data, we concluded that the decrease in ?(M)T-T upon cooling for complex 2 (Zn(2)Dy(2)) might be partly due to antiferromagnetic coupling between Dy(III) ions. The data from complex 4 (Ni(2)Gd(2)) were analyzed based on the preceding results and gave moderate ferromagnetic coupling between Ni(II) and Gd(III) with J = 0.26 cm(-1). A detailed study of magnetic properties of complex 1 (Ni(2)Dy(2)) was not possible, because of its strong orbital contributions from Dy(III) ions. In addition, frequency-dependent out-of-phase signals were clearly observed for both complexes 1 and 2 which can be attributed to magnetoanisotropy contributions from Dy(III) ions. PMID:23334432

Yu, Wan-Rong; Lee, Gene-Hsian; Yang, En-Che

2013-03-21

185

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

PubMed Central

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

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

2003-01-01

186

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

PubMed

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

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

2014-11-17

187

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

188

Prediction Study of the Mechanical and Thermodynamic Properties of the (R Sm, Eu, Gd, and Tb) Compounds  

NASA Astrophysics Data System (ADS)

The structural, elastic, and thermodynamic properties of the cubic anti-perovskite (R = Sm, Eu, Gd, and Tb) compounds have been investigated using first principles full-potential augmented-plane wave plus local orbitals (FP-APW+lo) method with the generalized gradient approximation. The ground-state quantities such as the lattice parameter, bulk modulus, and its pressure derivative, as well as elastic constants are estimated. Computed equilibrium lattice constants agree well with the available experimental data. The full set of first-order elastic constants and their pressure dependence, which have not been calculated or measured yet, have been determined. The elastic moduli increase linearly with increasing pressure and satisfy the generalized elastic stability criteria for cubic crystals under hydrostatic pressure. The shear modulus, Young's modulus, and Poisson's ratio are calculated for ideal polycrystalline aggregates. The Debye temperature is estimated from the average sound velocity. From the elastic parameter behavior, it is inferred that cubic anti-perovskites are ductile in nature and that the bonding is predominantly of an ionic nature. Following the quasi-harmonic Debye model, the temperature effect on the lattice constant, bulk modulus, heat capacity, and Debye temperature is calculated reflecting the anharmonic phonon effects.

Mekkaoui, F.; Litimein, F.; Khenata, R.; Merabiha, O.; Bouhemadou, A.; Varshney, D.; Soyalp, F.; U?ur, ?.; Bin-Omran, S.; Rached, D.

2013-11-01

189

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

SciTech Connect

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

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

2011-03-15

190

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

NASA Astrophysics Data System (ADS)

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

Morrison, Gregory; zur Loye, Hans-Conrad

2015-01-01

191

Dielectric properties of nano crystalline LnTiNbO6 (Ln = Ce, Pr, Nd, Sm, Gd, Dy, Er, Yb) ceramics  

NASA Astrophysics Data System (ADS)

Nano ceramics are potential candidates for various technological applications. Nano sized LnTiNbO6 ceramics are prepared using solution combustion technique. The properties of the nano ceramics are compared with that of micro ceramics. XRD shows that nano crystalline LnTiNbO6 (Ln= Ce, Pr, Nd, Sm) have aeschynite orthorhombic structure and Ln= Gd, Dy, Er, Yb have euxenite orthorhombic structure. The structure is confirmed by FTIR. From the TEM study, it is clear that polycrystalline powder is nano sized. The sintering temperature and sintering time of nano ceramics get lowered as compared to micro ceramics. The SEM image shows the surface morphology of the sintered sample. The variations of dielectric constant (?r), conductance (G) and loss factor (tan ?) of the samples are studied in the radio frequency range. The nano ceramics show enhanced dielectric properties than that of micro ceramics.

John, Fergy; Thomas, J. K.; Solomon, Sam

2015-02-01

192

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

Voß, Benjamin; Nordmann, Jörg; Uhl, Andreas; Komban, Rajesh; Haase, Markus

2012-12-01

193

Lanthanoid single-ion magnets based on polyoxometalates with a 5-fold symmetry: the series [LnP5W30O110]12- (Ln3+ = Tb, Dy, Ho, Er, Tm, and Yb).  

PubMed

A robust, stable and processable family of mononuclear lanthanoid complexes based on polyoxometalates (POMs) that exhibit single-molecule magnetic behavior is described here. Preyssler polyanions of general formula [LnP(5)W(30)O(110)](12-) (Ln(3+) = Tb, Dy, Ho, Er, Tm, and Yb) have been characterized with static and dynamic magnetic measurements and heat capacity experiments. For the Dy and Ho derivatives, slow relaxation of the magnetization has been found. A simple interpretation of these properties is achieved by using crystal field theory. PMID:22894703

Cardona-Serra, S; Clemente-Juan, J M; Coronado, E; Gaita-Ariño, A; Camón, A; Evangelisti, M; Luis, F; Martínez-Pérez, M J; Sesé, J

2012-09-12

194

Manifestation of ?-? Stacking Interactions in Luminescence Properties and Energy Transfer in Aromatically-Derived Tb, Eu and Gd Tris(pyrazolyl)borate Complexes.  

PubMed

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

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

2015-04-01

195

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

NASA Astrophysics Data System (ADS)

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

Thakur, Shweta; Rai, Radheshyam; Tiwari, Ashutosh

2014-11-01

196

Syntheses, structures, and physical properties of CsRE(2)Ag(3)Te(5) (RE = Pr, Nd, Sm, Gd-Er) and RbR(2)Ag(3)Te(5) (RE = Sm, Gd-Dy).  

PubMed

A new series of quaternary CsRE2Ag3Te5 (RE = Pr, Nd, Sm, Gd-Er) and RbRE2Ag3Te5 (RE = Sm, Gd-Dy), which have been synthesized from the elemental mixtures in ACl flux (A = Rb, Cs) and crystallized in the orthorhombic space group Cmcm, with a = 4.620(2)-4.504(2) Å, b = 16.232(8)-16.027(8) Å, c = 18.84(1)-18.32(2) and Z = 4, are isostructural to RbSm2Ag3Se5. These isostructural ARE2Ag3Te5 feature a three-dimensional tunnel framework constructed by ionically bound RETe6 octahedron and covalently bound AgTe4 tetrahedron in which tunnels are filled by A. Typical semiconducting behavior is revealed by the electrical conductivity, Seebeck coefficient, optical band gap measurement, and the theoretical calculations. The undoped sintered polycrystalline pellets of CsRE2Ag3Te5 (containing 1.1-1.7% CsCl impurity) show very low electrical conductivity (?r.t. = 0.5-2.4 S/cm), very low thermal conductivity (kr,t = 0.66-0.53 W/(m·K)), and moderate Seebeck coefficient (160-200 ?V/K at 700 K). PMID:24949650

Meng, Chang-Yu; Chen, Hong; Wang, Peng

2014-07-01

197

LnPO 4 : RE 3+ (La = La, Gd; RE = Eu, Tb) nanocrystals: solvo-thermal synthesis, microstructure and photoluminescence  

Microsoft Academic Search

Through altering the solvents, we have obtained the Eu3+\\/Tb3+ ions-doped LnPO4 (Ln = La, Gd) phosphors with different particle sizes, microstructures and morphologies via a facile solvo-thermal technology.\\u000a X-ray powder diffraction (XRD), transmission electron microscope (TEM), and scanning electron microscope (SEM) have shown\\u000a that the products using different solvents have various structures and morphologies. With the increase of DMA\\/water volume\\u000a ratio, the

Bing Yan; Jianfeng Gu; Xiuzhen Xiao

2010-01-01

198

Terbium-doped gadolinium oxysulfide (Gd2O2S:Tb) scintillation-based polymer optical fibre sensor for real time monitoring of radiation dose in oncology  

NASA Astrophysics Data System (ADS)

A PMMA based plastic optical fibre sensor for use in real time radiotherapy dosimetry is presented. The optical fibre tip is coated with a scintillation material, terbium-doped gadolinium oxysulfide (Gd2O2S:Tb), which fluoresces when exposed to ionising radiation (X-Ray). The emitted visible light signal penetrates the sensor optical fibre and propagates along the transmitting fibre at the end of which it is remotely monitored using a fluorescence spectrometer. The results demonstrate good repeatability, with a maximum percentage error of 0.5% and the response is independent of dose rate.

Lewis, E.; O'Keeffe, S.; Grattan, M.; Hounsell, A.; McCarthy, D.; Woulfe, P.; Cronin, J.; Mihai, L.; Sporea, D.; Santhanam, A.; Agazaryan, N.

2014-05-01

199

Photophysical properties of novel lanthanide (Tb 3+, Dy 3+, Eu 3+) complexes with long chain para-carboxyphenol ester p-L-benzoate (L = dodecanoyloxy, myristoyloxy, palmitoyloxy and stearoyloxy)  

Microsoft Academic Search

In this paper, a series of 12 binary luminescent lanthanide coordination compounds with long chain p-carboxyphenol ester were assembled. Both elemental analysis and infrared spectroscopy allowed to determine the complexes formula: LnL3, where Ln=Tb, Dy, Eu; L=p-dodecanoyloxybenzoate (12-OBA), p-myristoyloxybenzoate (14-OBA), p-palmitoyloxybenzoate (16-OBA) and p-stearoyloxybenzoate (18-OBA), respectively. The photophysical properties of these complexes were studied in detail with various of spectroscopies

Bing Xu; Bing Yan

2007-01-01

200

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 Néel 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

201

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

PubMed

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

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

2014-09-01

202

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

203

Sintering, microstructure and microwave dielectric properties of rare earth orthophosphates, RePO{sub 4} (Re = La, Ce, Nd, Sm, Tb, Dy, Y, Yb)  

SciTech Connect

Various rare earth orthophosphates, such as monazite and xenotime RePO{sub 4} (Re = La, Ce, Nd, Sm, Tb, Dy, Y, Yb) were prepared by a conventional solid-state reaction method. The crystal structure and microstructure of the sintered ceramics were investigated by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM), respectively. The dielectric properties were measured in the microwave region using a network analyzer. It was found that the monazite RePO{sub 4} could be sintered near 1400 deg. C, although the xenotime RePO{sub 4}, which had a smaller Re{sup 3+} ionic radius, could be sintered above 1600 deg. C. The permittivity ({epsilon}{sub r}) of the monazite structures was higher than that of the xenotime structures. This difference was explained by the differences in ionic polarizability and bond strength. Both monazite and xenotime rare earth orthophosphates, however, exhibited a high quality factor (Q x f), where Q = 1/tan {delta} and f is the measuring frequency, of greater than 60,000 GHz. The temperature coefficient of resonant frequency ({tau}{sub f}) was a negative value, ranging between -17 and -56 ppm/deg. C.

Cho, In-Sun; Choi, Geun Kyu; An, Jae-Sul [School of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Kim, Jeong-Ryeol [168 Materials Research Lab., Pennstate University, University Park, PA 16802 (United States); Hong, Kug Sun [School of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)], E-mail: kshongss@plaza.snu.ac.kr

2009-01-08

204

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

NASA Astrophysics Data System (ADS)

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

Khanna, A.; Dutta, P. S.

2014-11-01

205

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

PubMed

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

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

2014-07-28

206

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

207

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

208

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

PubMed

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

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

2013-04-14

209

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

NASA Technical Reports Server (NTRS)

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

Gonzalez-Titman, Carlos

1994-01-01

210

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

211

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

NASA Technical Reports Server (NTRS)

Measurements were made of the magnetic entropy and magnetization of powered samples of the compounds Dy2Ti2O7 and Gd3Al5O12. The magnetization was measured for temperatures at and below 4.2 K, in applied fields ranging to 7.0 tesla. Isothermal changes in magnetic entropy were measured for temperatures from 1.2 to 20 K, in applied fields up to 10 tesla. The results of the measurements are consistent with a doublet ground state for Dy2Ti2O7, and an eight-fold degenerate ground state for Gd3Al5O12. Absolute values of magnetic entropy have been obtained at the lower temperatures, permitting the isotherms to be properly located in the S-H plane with the use of adiabatic magnetization data. The iso-field lines in the S-T plane were determined. The results indicate that Dy2Ti2O7 can absorb a maximum of 71 + or - 4 joules/kg of heat at 4.2 K, while Gd3Al5O12 can absorb 233 + or - joules/kg at the same temperature. The large difference between the two is most likely a result of crystal field interactions in the dysoprosium compound. Both materials can be cycled adiabatically between 4.2 and 20 K.

Flood, D. J.

1973-01-01

212

Transitions of magnetic configuration at the interface of exchange-coupled bilayers: TbFe/GdFe as a model system  

NASA Astrophysics Data System (ADS)

The magnetization profile that forms in the soft part of an exchange-coupled hard/soft bilayer submitted to a rotating in-plane magnetic field has been studied both theoretically and experimentally. The evolution of the stable magnetic configurations as a function of the field orientation has been determined from micromagnetic calculations, for varying strength of the rotating field. The anisotropic magnetoresistance associated with these configurations has been deduced and compared with experimental results obtained on a TbFe/GdFe ferrimagnetic bilayer. A good agreement is obtained between calculated and measured data, without any parameter adjustment. As the applied field is rotated, a twisted magnetization distribution of Bloch type develops in the soft GdFe layer. The simulations show the existence of several possible stable magnetic profiles. These differ either by the amount of magnetization twist only or by the amount of twist and the chirality of the profile. Transport measurements allow one to determine which configuration is actually adopted by the system and in what circumstances the system switches from one configuration to another. Two types of transition are identified. The first one is related to the existence of a hard axis of magnetization in the GdFe layer. The second one corresponds to a change of chirality of the wall.

Montaigne, F.; Mangin, S.; Henry, Y.

2003-04-01

213

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

PubMed

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

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

2013-08-28

214

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

215

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

NASA Astrophysics Data System (ADS)

New fluorophore lanthanide complexes-Cloisite (LCs-C) nanohybrids have been prepared by the intercalation reaction of Cloisite Na+ with the tricationic lanthanide complexes (1-3), [M(PQ)3(DMF)2(H2O)2]3+ (M = Pr(III) (1), Gd(III) (2), and Dy(III) (3); PQ = 9,10-phenanthrenequinone), in aqueous solutions. The X-ray diffraction analysis of the modified clays (LCs-C) showed an increase in the interlayer distance (d) as compared to the pure Cloisite Na+. Field-emission scanning electron microscopy (FE-SEM) was used to study the morphology of the modified clays and the results were demonstrated a homogeneous morphology for the nanohybrids. The thermal behavior of the LCs-C nanohybrids was investigated using thermogravimetric analysis. Solid-state fluorescence properties of the LCs-C nanohybrids were also investigated. The results show that all tricationic complexes have a significant fluorescence at room temperature when the complexes are adsorbed onto Cloisite.

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

2015-02-01

216

Structural, electric and magnetic properties of CoFe1.8RE0.2O4 (RE=Dy, Gd, La) bulk materials  

NASA Astrophysics Data System (ADS)

We investigated the influence of rare earth (RE) additions on the structural, dielectric, magnetic and magnetostrictive properties of cobalt ferrite bulk materials. Three lanthanide ions with different ionic radii and magnetic properties were used as dopants: Dy, Gd, La. The structural properties of the sintered samples were investigated using X-ray diffraction, Raman spectroscopy and scanning electron microscopy. The room temperature hysteresis loops were obtained using a vibrating sample magnetometer. The frequency dependence of dielectric permittivity and tangent loss was investigated in the 20 Hz-20 kHz range. The variation of the magnetoelectric response with applied dc magnetic field was analyzed. The insertion of rare earth elements influenced the structural characteristics of the samples (density, cell edge, porosity) and the magnetic and electric properties. An increase in coercive field and a decrease in saturation magnetization and magnetostriction coefficient were observed. These results can be partially explained by the weaker nature of the RE3+-Fe3+ interaction compared to Fe3+-Fe3+ interaction and to the antiferromagnetic alignment of the REFeO3 second phase observed in the diffraction patterns after sintering process.

Dascalu, G.; Popescu, T.; Feder, M.; Caltun, O. F.

2013-05-01

217

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

PubMed

New fluorophore lanthanide complexes-Cloisite (LCs-C) nanohybrids have been prepared by the intercalation reaction of Cloisite Na(+) with the tricationic lanthanide complexes (1-3), [M(PQ)3(DMF)2(H2O)2](3+) (M=Pr(III) (1), Gd(III) (2), and Dy(III) (3); PQ=9,10-phenanthrenequinone), in aqueous solutions. The X-ray diffraction analysis of the modified clays (LCs-C) showed an increase in the interlayer distance (d) as compared to the pure Cloisite Na(+). Field-emission scanning electron microscopy (FE-SEM) was used to study the morphology of the modified clays and the results were demonstrated a homogeneous morphology for the nanohybrids. The thermal behavior of the LCs-C nanohybrids was investigated using thermogravimetric analysis. Solid-state fluorescence properties of the LCs-C nanohybrids were also investigated. The results show that all tricationic complexes have a significant fluorescence at room temperature when the complexes are adsorbed onto Cloisite. PMID:25305612

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

2015-02-25

218

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

219

Color tunable emission in Ce3+ and Tb3+ co-doped Ba2Ln(BO3)2Cl (Ln = Gd and Y) phosphors for white light-emitting diodes  

NASA Astrophysics Data System (ADS)

Ce3+ and Tb3+ 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 Ce3+ to Tb3+ in this system. The phosphors exhibit both a blue emission from Ce3+ and a green emission from Tb3+ under near ultraviolet light excitation with 325-375 nm wavelength. Emission colors of phosphors could be tuned from deep blue through cyan to green by adjusting the Tb3+ concentrations. The energy transfer efficiency and emission intensity of Ba2Y(BO3)2Cl:Ce3+, Tb3+ precede those of Ba2Gd(BO3)2Cl:Ce3+, Tb3+, and the sample Ba2Y(BO3)2Cl:0.03Ce3+, 0.10Tb3+ is the best candidate for n-UV LEDs.

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

2013-12-01

220

Rapid, large-scale, morphology-controllable synthesis of YOF:Ln3+ (Ln = Tb, Eu, Tm, Dy, Ho, Sm) nano-/microstructures with multicolor-tunable emission properties.  

PubMed

YOF:Ln(3+) (Ln = Tb, Eu, Tm, Dy, Ho, Sm) nano-/microstructures with a variety of novel and well-defined morphologies, including nanospheres, nanorod bundles, and microspindles, have been prepared through a convenient modified urea-based homogeneous precipitation (UBHP) technique followed by a heat treatment. The sizes and morphologies of the YOF products could be easily modulated by changing the pH values and fluoride sources. XRD, TG-DTA, FT-IR, SEM, and TEM, as well as photoluminescence (PL) and cathodoluminescence (CL) spectra, were used to characterize the prepared samples. The YOF:Ln(3+) nanospheres show the characteristic f-f transitions of Ln(3+) (Ln = Tb, Eu, Tm, Dy, Ho, Sm) ions and give bright green, red, blue, yellow, blue-green, and yellow-orange emission, respectively, under UV light and low-voltage electron beam excitation. Furthermore, YOF:0.03Tb(3+) phosphors exhibit green luminescence with superior properties in comparison with the commercial phosphor ZnO:Zn to a degree, which is advantageous for improving display quality. Because of the simultaneous luminescence of Ln(3+) in the YOF host, the luminescence colors of YOF:Ln(3+) phosphors can be precisely adjusted by changing the doped Ln(3+) ions and corresponding concentrations, which makes these materials hold great promise for applications in field-emission displays. PMID:24195545

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

2013-11-18

221

Structure and magnetic properties of sulfides of the type Cd RE2S 4 and Mg(Gd xYb 1- x) 2S 4  

NASA Astrophysics Data System (ADS)

Cd RE2S 4 ( RE = Gd, Tb, Dy, Ho, Er, Tm, and Yb) and Mg(Gd xYb 1- x) 2S 4 were prepared by solid-state reactions. All the cadmium-containing compounds are cubic, i.e., the Th 3P 4 structure for Gd, Tb, and Dy and the spinel type for all the others. The first three compounds were deficient in CdS. In the case of the Mg system, for x = 1 the system is cubic Th 3P 4, for x = 0 cubic spinel, and for 0 < x < 1 orthorhombic MnY 2S 4 (Cmc2 1). All the materials studied are paramagnetic above 77 K. Below 77 K in the magnesium family both cubic materials are paramagnetic down to 4.2 K and the orthorhombic materials show magnetic ordering. In the cadmium family all but CdTm 2S 4 show exchange coupling.

Ben-Dor, L.; Shilo, I.

1980-11-01

222

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

223

Microscopic evidence of spin state order and spin state phase separation in layered cobaltites RBaCo2O5.5 with R=Y, Tb, Dy, and Ho.  

PubMed

We report muon-spin relaxation measurements on the magnetic structures of RBaCo2O(5.5) with R=Y, Tb, Dy, and Ho. Three different phases, one ferrimagnetic and two antiferromagnetic, are identified below 300 K. They consist of different ordered spin state arrangements of high-, intermediate-, and low-spin Co3+ of CoO6 octahedra. Phase separation into well separated regions with different spin state order is observed in the antiferromagnetic phases. The unusual strongly anisotropic magnetoresistance and its onset at the FM-AFM phase boundary is explained. PMID:18764150

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

2008-07-01

224

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

Microsoft Academic Search

Seven new quaternary metal sulfides, KY2CuS4, KNd2CuS4, KSm2CuS4, KTb2CuS4, KHo2CuS4, K2Dy4Cu4S9, and K2Ho4Cu4S9, were prepared by the reactive flux method. All crystallographic data were collected at 153K. The isostructural compounds KLn2CuS4 (Ln=Y, Nd, Sm, Tb, Ho) crystallize in space group Cmcm of the orthorhombic system with four formula units in cells of dimensions (Ln, a, b, c (Å)): Y, 3.9475(9),

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

2003-01-01

225

Syntheses, structures, physical properties, and electronic structures of KLn2CuS4 (Ln=Y, Nd, Sm, Tb, Ho) and K2Ln4Cu4S9 (Ln=Dy, Ho)  

Microsoft Academic Search

Seven new quaternary metal sulfides, KY2CuS4, KNd2CuS4, KSm2CuS4, KTb2CuS4, KHo2CuS4, K2Dy4Cu4S9, and K2Ho4Cu4S9, were prepared by the reactive flux method. All crystallographic data were collected at 153K. The isostructural compounds KLn2CuS4 (Ln=Y, Nd, Sm, Tb, Ho) crystallize in space group Cmcm of the orthorhombic system with four formula units in cells of dimensions (Ln, a, b, c (Å)): Y, 3.9475(9),

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

2003-01-01

226

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

227

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

228

Structural investigation of the new Ca{sub 3}Ln{sub 2}Ge{sub 3}O{sub 12} (Ln=Pr, Nd, Sm, Gd and Dy) compounds and luminescence spectroscopy of Ca{sub 3}Gd{sub 2}Ge{sub 3}O{sub 12} doped with the Eu{sup 3+} ion  

SciTech Connect

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

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

2013-09-15

229

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

PubMed

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

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

2015-02-16

230

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

SciTech Connect

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

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

2012-12-15

231

Preparation, structure, and peritectic transition of RBa{sub 1.5}Sr{sub 0.5}Cu{sub 3}O{sub y} (R = La, Nd, Sm, Eu, Gd, Dy, Ho, and Y) superconductors  

SciTech Connect

A series of single-phase RBa{sub 1.5}Sr{sub 0.5}Cu{sub 3}O{sub y} (T = La, Nd, Sm, Eu, Gd, Dy, Ho, and Y) compounds with a triple-perovskite unit cell has been prepared by solid-state reaction method. Samples with a larger radius of the R ion (R = La and Nd) are tetragonal, whereas those with a smaller radius of the R ion (R = Sm, Eu, Gd, Dy, Ho, and Y) are orthorhombic. Unit-cell parameters of RBa{sub 1.5}Sr{sub 0.5}Cu{sub 3}O{sub y} decrease monotonically with a decrease of the radius of the R ion. A maximum at R = Nd, Sm, and Eu is found in the peritectic transition temperature (t{sub p}), the amount of oxygen loss ({Delta}w) in this transition, and the enthalpy of fusion ({Delta}H{sub f}), respectively. An increase in the {Delta}H{sub f} is correlated with increasing t{sub p} for the respective orthorhombic and tetragonal phases of RBa{sub 1.5}Sr{sub 0.5}Cu{sub 3}O{sub y} compounds. {Tc} of the title compounds gradually increased from 52 to 86 K with a decrease in the radius of the R ion.

Lin, M.Y.; Huang, J.T.; Kao, H.C.I.; Wang, C.M. [Tamkang Univ., Tamsui (Taiwan, Province of China). Dept. of Chemistry] [Tamkang Univ., Tamsui (Taiwan, Province of China). Dept. of Chemistry

1998-08-01

232

Synthesis and spectroscopic properties of Yb(3+) and Tb(3+) co-doped GdBO3 materials showing down- and up-conversion luminescence.  

PubMed

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

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

2015-02-17

233

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

234

Raman and x-ray studies of Ce(1 - x) RE(x) O(2 - y), where RE = La, Pr, Nd, Eu, Gd, and Tb  

NASA Astrophysics Data System (ADS)

Powdered samples of the type Ce(1 - x) RE(x) O(2 - y), where RE = La, Pr, Nd, Eu, Gd, and Tb, are synthesized over the range O less than or equal to x less than or equal to 0.5 starting from nitrate solutions of the rare earths. X-ray diffraction and Raman scattering are used to analyze the samples. These compounds, at least in the low doping regime and for strictly trivalent dopants, form solid solutions that maintain the fluorite structure of CeO2 with a change in lattice constant that is approximately proportional to the dopant ionic radius. The single allowed Raman mode, which occurs at 465 cm(exp -1) in pure CeO2, is observed to shift to lower frequency with increasing doping level for all the rare earths. However, after correcting for the Gruneisen shift from the lattice expansion, the frequency shift is actually positive for all the strictly trivalent ions. In addition, the Raman line broadens and becomes asymmetric with a low frequency tail, and a new broad feature appears in the spectrum at approximately 570 cm(exp -1). These changes in the Raman spectrum are attributed to O vacancies, which are introduced into the lattice whenever a trivalent RE is substituted for Ce(+4). This conclusion is supported by a simple model calculation of the effects of O vacancies on the Raman spectrum. The model uses a Green's function technique with the vacancies treated as point defects with zero mass.

McBride, J. R.; Hass, K. C.; Poindexter, B. D.; Weber, W. H.

1994-08-01

235

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

PubMed

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

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

2013-01-01

236

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

237

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

PubMed

The reaction of N-methydiethanolamine (mdeaH2), benzoic acid, FeCl3, and Ln(NO3)3·6H2O or LnCl3·xH2O yields a series of decanuclear coordination clusters, [Ln3Fe7(?4-O)2(?3-OH)2(mdea)7(?-benzoate)4(N3)6]·4MeCN·H2O, where Ln = Gd(III) (1) or Tb(III) (2), and [Er3Fe7(?4-O)2(?3-OH)2(mdea)7(?-benzoate)4(N3)5(MeOH)]Cl·7.5H2O·11.5MeOH (3). The isostructural compounds 1-3 all crystallize isotypically in the triclinic space group P1? with Z = 2, as does the previously reported dysprosium analogue 4. Six of the Fe(III) ions are pseudooctahedrally coordinated, whereas the seventh has a trigonal-bipyramidal coordination geometry. Temperature-dependent direct-current magnetic susceptibility studies indicate that intracluster antiferromagnetic interactions are dominant in 1-3. The frequency-dependent out-of-phase (??) alternating-current susceptibility reveals that 2 undergoes a slow relaxation of its magnetization, presumably resulting from anisotropy of the Tb(III) ions. Between 30 and 295 K, the (57)Fe Mössbauer spectra reveal paramagnetic behavior with six partially resolved quadrupole doublets, one for the trigonal-bipyramidal Fe(III) site and five for the six pseudooctahedral Fe(III) sites. The Mössbauer spectra of 2 and 3 obtained between 3 and 30 K are consistent with the presence of Fe(III) intracluster antiferromagnetic coupling with slow magnetic relaxation relative to the Larmor precession time. Further, the observed changes in the effective magnetic field values in the spectra measured at 3 K with increasing applied field are consistent with the effect of the local spin polarization along the applied magnetic field direction, a behavior reminiscent of antiparallel spin-coupled iron molecular paramagnetic systems. PMID:24089701

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

2013-10-21

238

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

239

Crystal structures and reference powder patterns of BaR{sub 2}ZnO{sub 5} (R = La, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, and Tm)  

SciTech Connect

Reference x-ray powder patterns and the crystal structures of the lanthanide compounds, BaR{sub 2}ZnO{sub 5}, in which R = La, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, or Tm were determined by the x-ray Rietveld refinement technique. A structural trend was confirmed for this series of compounds. The compounds with smaller ionic radii (R = Sm, Eu, Gd, Dy, Ho, Y, Er, or Tm) are isostructural to the orthorhombic green phase (BaY{sub 2}CuO{sub 5}). The lattice parameters for compounds with R = Tm to Sm range from a = 7.01855(9) {angstrom} to 7.20452(14) {angstrom}, b = 12.25445(17) {angstrom} to 12.5882(2) {angstrom}, and c = 5.6786(14) {angstrom} to 5.81218(11) {angstrom}, respectively. R is sevenfold coordinated inside a monocapped trigonal prism. These prisms share edges to form wave-like chains parallel to the long b-axis. The BaR{sub 2}ZnO{sub 5} compounds which contain larger size R (La and Nd) crystallize in the tetragonal space group 14/mcm. The lattice parameters are a = 6.90982(10) and c = 11.5977(2) {angstrom} for BaLa{sub 2}ZnO{sub 5}, and a = 6.75979(5) {angstrom} and c = 11.54560(12) {angstrom} for BaNd{sub 2}ZnO{sub 5}. The structure consists of ZnO{sub 4} tetrahedra (instead of planar CuO{sub 4} groups as found in BaR{sub 2}CuO{sub 5}) with 10-fold coordinated bicapped square prismatic Ba and 8-fold coordinated bicapped trigonal prismatic R ions between them. The reference x-ray powder patterns will be submitted to the Powder Diffraction File (PDF).

Kaduk, J.A. [Amoco Corp., Naperville, IL (United States); Wong-Ng, W.; Toby, B.H. [National Inst. of Standards and Technology, Gaithersburg, MD (United States); Greenwood, W.; Dillingham, J. [Univ. of Maryland, College Park, MD (United States). Geology Dept.

1999-03-01

240

The mass of the nucleus148Dy  

NASA Astrophysics Data System (ADS)

Using ?? coincidences the EC(K)/? + ratio for the ? decay148Dy?148Tb has been determined.148Dy has been produced through the irradiation of93Nb with 249 MeV58Ni ions. The mass of148Dy has been deduced. With the help of known Q? values the masses of152Er,156Yb,160Hf and164W have been obtained. The experimental masses are compared with different current mass formulae.

Spanier, L.; Gui, S. Z.; Hick, H.; Nolte, E.

1981-06-01

241

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

PubMed

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

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

2015-03-24

242

Glass-forming Mg–Cu–RE (RE = Gd, Pr, Nd, Tb, Y, and Dy) alloys with strong oxygen resistance in manufacturability  

Microsoft Academic Search

One of the unsolved problems for the manufacturability and the applications of bulk metallic glasses is that their glass-forming ability is very sensitive to the preparation vacuum and impurity of components because oxygen in the environments would markedly deteriorate the glass-forming ability. Here we report that the addition of rare earth elements can significantly improve the glass-forming ability and manufacturability

X. K. Xi; R. J. Wang; D. Q. Zhao; M. X. Pan; W. H. Wang

2004-01-01

243

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

PubMed

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

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

2012-11-28

244

Photoluminescence of Pr 3+, Sm 3+ and Dy 3+: SiO 2-Al 2O 3-LiF-GdF 3 glass ceramics and Sm 3+, Dy 3+: GeO 2-B 2O 3-ZnO-LaF 3 glasses  

NASA Astrophysics Data System (ADS)

In this paper, we present the absorption and photoluminescence properties of Pr 3+, Sm 3+ and Dy 3+-doped transparent oxyfluoride alumino-silicate glass ceramics and Sm 3+ and Dy 3+-doped oxyfluoride germanate glasses. The X-ray diffraction (XRD) and differential thermal analysis (DTA) profiles of these glasses have been carried out, to confirm their structure and thermal stability. These glasses or glass ceramics have shown strong emission and absorption bands in visible and near-infrared (NIR) region. From the measured absorption spectra, Judd-Ofelt (J-O) intensity parameters ( ?2, ?4 and ?6) have been calculated for all the studied ions. Compared to Pr 3+, Sm 3+ and Dy 3+ doped glasses, their respective glass ceramics have shown stronger emissions due to LiGdF 4 crystalline phase in alumino-silicate glass ceramics. For Pr 3+ doped glass and glass ceramic, emission bands centered at 527 nm( 3P 0? 3H 5), 610 nm( 3P 0? 3H 6), 640 nm( 3P 0? 3F 2), 678 nm( 3P 1? 3F 3), 702 nm( 3P 0? 3F 3) and 721 nm( 3P 0? 3F 4) have been observed with 445 nm( 3H 4? 3P 2) excitation wavelength. Of them, 640 nm( 3P 0? 3F 2) has shown bright red emission. Emission bands of 4G 5/2? 6H 5/2 (562 nm), 4G 5/2? 6H 7/2 (598 nm), 4G 5/2? 6H 9/2 (644 nm) and 706 nm( 4G 5/2? 6H 11/2) for the Sm 3+: glass and glass ceramic, with excitation at 6H 5/2? 4F 7/2 (402 nm) have been recorded. Of them, 4G 5/2? 6H 7/2 (598 nm) has shown a bright orange emission. With regard to the Dy 3+: glass and glass ceramic, a bright fluorescent yellow emission at 576 nm( 4F 9/2? 6H 13/2) and blue emission at 485 nm( 4F 9/2? 6H 15/2) have been observed, apart from 4F 9/2? 6H 11/2 (662 nm) emission transition for glass ceramic with an excitation at 388 nm( 6H 15/2? 4I 13/2+ 4F 7/2) wavelength. For germanate glasses, emission bands of 4G 5/2? 6H 5/2 (564 nm), 4G 5/2? 6H 7/2 (601 nm), 4G 5/2? 6H 9/2 (644 nm) and 705 nm( 4G 5/2? 6H 11/2) for the Sm 3+: glass, with an excitation at 6H 5/2? 4F 7/2 (401 nm) have been recorded. Of them, 4G 5/2? 6H 7/2 (601 nm) has shown a bright orange emission. With regard to the Dy 3+: glass, a bright fluorescent yellow emission at 576 nm( 4F 9/2? 6H 13/2) and blue emission at 482 nm( 4F 9/2? 6H 15/2) have been observed, apart from 4F 9/2? 6H 11/2 (661 nm) emission transition with an excitation at 386 nm( 6H 15/2? 4I 13/2+ 4F 7/2) wavelength. The stimulated emission cross-sections of all the emission bands of Pr 3+, Sm 3+ and Dy 3+: glasses and glass ceramics have been computed based on their measured full-width at half maxima (FWHM, ? ?) and measured lifetimes ( ? m).

Lakshminarayana, G.; Qiu, Jianrong

2009-05-01

245

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

PubMed

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

Gardner, Jonathan; Morrison, Finlay D

2014-08-14

246

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

PubMed

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

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

2014-11-17

247

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

SciTech Connect

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

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

2013-02-15

248

Tuberculosis (TB)  

MedlinePLUS

... JavaScript on. Read more information on enabling JavaScript. Tuberculosis (TB) Skip Content Marketing Share this: Main Content ... thought to be infected with TB bacteria, Mycobacterium tuberculosis ( Mtb ). TB is a chronic bacterial infection. It ...

249

Preparation and spectroscopic properties of PMMA\\/GdAlO3:RE 3+ (RE = Pr, Eu or Tb) composite films for application in scintillation devices  

Microsoft Academic Search

The conformation of the materials for scintillation applications is very important because it determines the applicability and cost of ionizing radiation detectors devices. Polymeric composite films have been studied due to their properties like flexibility and control of shape and dimensions. In this work, we related the preparation and optical properties of GdAlO3:RE 3+ scintillator materials dispersed in PMMA films.

H. H. S. Oliveira; M. A. Cebim; M. R. Davolos

250

Down- and up-conversion of femtosecond light pulse excitation into visible luminescence in cerium-doped Lu2SiO5 - Gd2SiO5 solid solution crystals co-doped with Sm3+ or Dy3+.  

PubMed

Luminescence phenomena following femtosecond pulse excitation in UV and IR of Ce3+ + Sm3+ and Ce3+ + Dy3+ systems in Lu2SiO5 - Gd2SiO5 single crystals are investigated. Effect of excitation wavelength in the UV on Ce3+ luminescence is interpreted assuming selective excitation of weakly interacting Ce1 and Ce2 sites. IR-excited up-converted spectra differ as compared to UV-excited spectra in that the contribution of Sm3+ or Dy3+ luminescence is higher and the Ce3+ luminescence originates essentially in Ce1 sites. It has been concluded that excitation mechanism of up-conversion involves energy transfer from free electrons created in conduction band of the host. PMID:25836492

Ryba-Romanowski, W; Macalik, B; Berkowski, M

2015-02-23

251

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

252

Tuberculosis (TB): Treatment  

MedlinePLUS

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

253

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

NASA Astrophysics Data System (ADS)

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

Matyjasik, S.; Shaldin, Yu. V.

2013-11-01

254

Tuberculosis (TB)  

MedlinePLUS

... JavaScript on. Read more information on enabling JavaScript. Tuberculosis (TB) Skip Content Marketing Share this: Main Content ... HIV/AIDS Multidrug-Resistant and Extensively Drug-Resistant Tuberculosis Research Agenda (PDF) TB Research at NIAID Research ...

255

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

SciTech Connect

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

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

2014-07-01

256

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

NASA Astrophysics Data System (ADS)

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

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

2006-01-01

257

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

258

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

PubMed

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

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

2015-02-16

259

Difference Between Latent TB Infection and Active TB Disease  

MedlinePLUS

... 1 of 2) TB Elimination The Difference Between Latent TB Infection and TB Disease National Center for ... latent TB infection and TB disease. What is Latent TB Infection? Persons with latent TB infection do ...

260

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

NASA Astrophysics Data System (ADS)

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

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

2002-07-01

261

Gadolinium complex and phosphorescent probe-modified NaDyF4 nanorods for T1- and T2-weighted MRI/CT/phosphorescence multimodality imaging.  

PubMed

To compensate for the deficiencies of individual imaging modalities, lanthanide-based nanoparticles are ideal building blocks for multifunctional contrast agents. Herein, oleic acid-coated NaDyF4 nanorods (DyNPs) were synthesized by the hydrothermal method, and then coated with ?-cyclodextrin (?-CD) and modified with gadolinium complex (Gd-DTPA) to obtain hydrophilic and functionalized nanoparticles (DyNPs-Gd). By loading the phosphorescent probe (iridium-complex) within the surface hydrophobic layer, the developed nanophosphors (DyNPs-Gd-Ir) could be further applied in phosphorescent cell labeling. The Dy in the host induces a high X-ray absorption ability for X-ray computed tomography (CT) and negative enhancement for T2-weighted magnetic resonance imaging (MRI), whereas positive contrast for T1-weighted MRI results from the Gd-DTPA. DyNPs-Gd-Ir has been successfully applied to T1- and T2-weighted MRI/CT in vivo. Toxicity studies demonstrated that DyNPs-Gd-Ir exhibited low toxicity to living systems. Therefore, DyNPs-Gd-Ir could be a platform for next-generation contrast agents for T1- and T2-weighted MRI/CT/phosphorescence multimodal imaging. PMID:24119502

Zhou, Jing; Lu, Zhigao; Shan, Guogang; Wang, Sihui; Liao, Yi

2014-01-01

262

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

263

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

264

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

265

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

266

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

NASA Astrophysics Data System (ADS)

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

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

2009-01-01

267

Stellar neutron capture cross sections of Pr and Dy isotopes  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 141Pr,160Dy,161Dy,162Dy,163Dy, and 164Dy have been measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p,n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? Barium Fluoride Detector. The cross sections were determined relative to the gold standard. For the first time the correction for undetected capture events was completely obtained from experimental information, using capture cascades derived from measurements with an analog-to-digital converter system. The cross section ratios could be determined with an overall uncertainty of 1-1.5 %, an average improvement compared to previous measurements by a factor 4. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT=8 keV and 100 keV. For most of the isotopes there is reasonable agreement with recent evaluations, but discrepancies of ~20% were obtained for 160Dy and 164Dy. The experimental data were complemented by statistical model calculations in order to describe the cross section enhancements in the stellar environment. The astrophysical implications of the present data include the quest for the origin of 160Dy, the decomposition of the Dy abundances in the respective s- and r-process contributions, branchings of the s-process chain at the terrestrially stable isotopes 157Gd and 163Dy, and the isotopically anomalous dysprosium in meteoritic inclusions.

Voss, F.; Wisshak, K.; Arlandini, C.; Käppeler, F.; Kazakov, L.; Rauscher, T.

1999-02-01

268

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 ...

269

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 ...

270

Preparation, crystal structures, and magnetic features for a series of dinuclear [Ni(II)Ln(III)] Schiff-base complexes: evidence for slow relaxation of the magnetization for the Dy(III) derivative.  

PubMed

A series of dinuclear [Ni(II)Ln(III)] Schiff-base complexes (using a Schiff-base dicompartmental ligand derived from o-vanillin [H(2)valpn = 1,3-propanediylbis(2-iminomethylene-6-methoxy-phenol)]) with Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and a hydroxo-bridged tetranuclear [Ni(II)Yb(III)] are reported. The crystal structures have been solved for 10 dinuclear complexes revealing four arrangements for the dinuclear units, which are modulated by the coordinated solvent molecules and the nitrato-anion interactions. The magnetic behaviors have been investigated, and the nature of the Ni(II)-Ln(III) exchange interaction has been emphasized by comparison with the behavior of the related [Zn(II)Ln(III)] derivatives. This allowed for establishing that the interaction within these compounds is antiferromagnetic with the 4f ions of the beginning of the Ln series and turns ferromagnetic from Gd(III) toward the end of the series. AC susceptibility investigations clearly show the occurrence of slow relaxation processes of the magnetization close to 2 K for the dinuclear [Ni(II)Dy(III)] complex. PMID:21634381

Pasatoiu, Traian D; Sutter, Jean-Pascal; Madalan, Augustin M; Fellah, Fatima Zohra Chiboub; Duhayon, Carine; Andruh, Marius

2011-07-01

271

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

NASA Astrophysics Data System (ADS)

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

Mioduski, Tomasz; Gumi?ski, Cezary; Zeng, Dewen

2009-12-01

272

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

273

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

274

New tetragonal derivatives of cubic NaZn{sub 13}-type structure: RNi{sub 6}Si{sub 6} compounds, crystal structure and magnetic ordering (R=Y, La, Ce, Sm, Gd–Yb)  

SciTech Connect

Novel RNi{sub 6}Si{sub 6} compounds adopt the new CeNi{sub 6}Si{sub 6}-type structure for R=La–Ce (tP52, space group P4/nbm N 125-1) and new YNi{sub 6}Si{sub 6}-type structure for R=Y, Sm, Gd–Yb (tP52, space group P4{sup ¯}b2N 117) that are tetragonal derivative of NaZn{sub 13}-type structure, like LaCo{sub 9}Si{sub 4}-type. The CeNi{sub 6}Si{sub 6}, GdNi{sub 6}Si{sub 6}, TbNi{sub 6}Si{sub 6}, DyNi{sub 6}Si{sub 6} and HoNi{sub 6}Si{sub 6} compounds are Curie–Weiss paramagnets down to ?30 K, and do not order magnetically down to 5 K. However, the inverse paramagnetic susceptibility of LaNi{sub 6}Si{sub 6} does not follow Curie–Weiss law. The DyNi{sub 6}Si{sub 6} shows ferromagnetic-like saturation behaviour at 5 K in applied fields of 50 kOe, giving rise to a magnetic moment value of 6.5 ?{sub B}/f.u. in 50 kOe. The powder neutron diffraction study in zero applied filed indicates square modulated the c-collinear antiferromagnetic ordering of TbNi{sub 6}Si{sub 6} with K=[±1/4, ±1/4, 0] wave vector below ?10 K. - Graphical abstract: Novel (La, Ce)Ni{sub 6}Si{sub 6} compounds adopt the new CeNi{sub 6}Si{sub 6}-type structure and (Y, Sm, Gd–Yb) adopt the new YNi{sub 6}Si{sub 6}-type structure that are tetragonal derivative of NaZn{sub 13}-type structure, like LaCo{sub 9}Si{sub 4}-type. The CeNi{sub 6}Si{sub 6}, GdNi{sub 6}Si{sub 6}, TbNi{sub 6}Si{sub 6}, DyNi{sub 6}Si{sub 6} and HoNi{sub 6}Si{sub 6} compounds are Curie–Weiss paramagnets down to ?30 K, and do not order magnetically down to 4.2 K. The powder neutron diffraction study in zero applied filed indicates square modulated the c-collinear antiferromagnetic ordering of TbNi{sub 6}Si{sub 6} with K=[±1/4, ±1/4, 0] wave vector below ?10 K. Display Omitted - Highlights: • The new (La, Ce)Ni{sub 6}Si{sub 6} compounds adopt the new CeNi{sub 6}Si{sub 6}-type structure. • The new (Y, Sm, Gd–Yb)Ni{sub 6}Si{sub 6} compounds adopt the new YNi{sub 6}Si{sub 6}-type structure. • TbNi{sub 6}Si{sub 6} has square modulated c-collinear antiferromagnetic ordering below ?10 K.

Pani, M.; Manfrinetti, P.; Provino, A. [INFM and Dipartimento di Chimica e Chimica Industriale, Universita‘ di Genova, Via Dodecaneso 31, 16146 Genova (Italy); Yuan, Fang; Mozharivskyj, Y. [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, ON, Canada L8S 4M1 (Canada); Morozkin, A.V., E-mail: morozkin@general.chem.msu.ru [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Knotko, A.V.; Garshev, A.V. [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Yapaskurt, V.O. [Department of Petrology, Geological Faculty, Moscow State University, Leninskie Gory, Moscow 119992 (Russian Federation); Isnard, O. [Université Grenoble Alpes, Inst NEEL, BP166, F-38042 Grenoble (France); CNRS, Institut NEEL, 25 rue des martyrs, F-38042 Grenoble (France)

2014-02-15

275

TB and Antibiotic Resistance  

NSDL National Science Digital Library

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

Marion Fass (Beloit College; Biology)

2006-05-20

276

Antiferromagnetic three-sublattice Tb ordering in Tb14 Ag51  

NASA Astrophysics Data System (ADS)

Bulk magnetic, x-ray, and neutron-diffraction measurements were performed on polycrystalline Tb14Ag51 in the temperature range from 1.5K to room temperature. Its chemical Gd14Ag51 -type structure corresponding to space group P6/m has been refined at 300 and at 30K . Combined with group-theoretical symmetry analysis, we show that the magnetic structure of this intermetallic compound is of a different k=(1/3,1/3,0) type with three magnetic Tb sublattices ordering simultaneously below TN=27.5(5)K according to the combined irreducible representations ?4 and ?6 .

Fischer, P.; Pomjakushin, V.; Keller, L.; Daoud-Aladine, A.; Sikora, W.; Dommann, A.; Hulliger, F.

2005-10-01

277

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

PubMed

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

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

2013-11-21

278

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 ...

279

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 ...

280

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 ...

281

Spherical, oblate, and prolate nuclear shapes near 146Gd  

NASA Astrophysics Data System (ADS)

Proton and neutron single particle level spacings are determined for the A=146 mass region, using a rotationally invariant interaction and recent experimental data. Excitation energies of spherical and deformed high spin states in 147Gd, the transition probability B(E2 10+-->8+) for several N=82 isotones, and the 0+ excited state spectra of, and neutron pair transfer probabilities for, levels in 146Gd and 144Sm are calculated. Comparisons with experimental data are made. NUCLEAR STRUCTURE 144Sm, 146Gd, 147Gd, 148Dy, 150Er, 152Yb, 154Hf; calculated single particle spectrum, high spin yrast levels, B(E2), 0+ excited state spectrum, pair transfer probability.

Chasman, R. R.

1983-09-01

282

Structural, spectroscopic, and theoretical comparison of traditional vs recently discovered Ln(2+) ions in the [K(2.2.2-cryptand)][(C5H4SiMe3)3Ln] complexes: the variable nature of Dy(2+) and Nd(2+).  

PubMed

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

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

2015-01-14

283

Magnetic and magnetocaloric properties of Gd3-xTbxGa5O12 (x=0, 1, 2, 3) garnets  

NASA Astrophysics Data System (ADS)

The structure and magnetocaloric properties of Tb substituted Gd3Ga5O12 garnets have been investigated. The structural refinement of X-ray diffraction patterns show that Gd3-xTbxGa5O12 (x=0, 1, 2, 3) are isostructural, with the symmetry of a cubic space group Ia3¯d. The temperature dependence of magnetization studies indicate that all the samples follow Curie-Weiss paramagnetic behavior above 25 K and the effective magnetic moment increases with Tb concentration. The low temperature magnetization studies suggest that there exists a field dependent antiferromagnetic ordering of rare earth ions in Tb substituted Gd3Ga5O12, which in turn leads to a lower magnetic moment in Gd3-xTbxGa5O12 (x=1, 2, 3), compared to that of Gd3Ga5O12. Magnitude of field corresponding to the antiferromagnetic ordering is found to be dependent on temperature as well as on Tb concentration. Magnetocaloric effect analysis confirms that Tb substitution enhances the magnetic entropy change at higher temperatures and Gd3-xTbxGa5O12 (x=1, 2, 3) are better candidates than Gd3Ga5O12 for low fields and low temperature magnetic refrigeration applications.

Reshmi, C. P.; Savitha Pillai, S.; Suresh, K. G.; Varma, Manoj Raama

2012-06-01

284

Magnetic ordering at anomalously high temperatures in Dy at extreme pressures  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

285

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

286

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

SciTech Connect

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

Pradhan, M. K.; Mukherjee, A.; Basu, P.; Goswami, A.; Kshetri, R.; Roy, Subinit; Chowdhury, P. Roy; Sarkar, M. Saha; Palit, R.; Parkar, V. V.; Santra, S.; Ray, M. [Nuclear Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhan Nagar, Kolkata-700064 (India); Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Mumbai-400005 (India); Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Department of Physics, Behala College, Parnasree, Kolkata-700060 (India)

2011-06-15

287

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

SciTech Connect

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

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

2014-03-07

288

Ternary rare-earth ruthenium and iridium germanides RE{sub 3}M{sub 2}Ge{sub 3} (RE=Y, Gd–Tm, Lu; M=Ru, Ir)  

SciTech Connect

Through arc-melting reactions of the elements and annealing at 800 °C, the ternary rare-earth germanides RE{sub 3}Ru{sub 2}Ge{sub 3} and RE{sub 3}Ir{sub 2}Ge{sub 3} have been prepared for most of the smaller RE components (RE=Y, Gd–Tm, Lu). In the iridium-containing reactions, the new phases RE{sub 2}IrGe{sub 2} were also generally formed as by-products. Powder X-ray diffraction revealed orthorhombic Hf{sub 3}Ni{sub 2}Si{sub 3}-type structures (space group Cmcm, Z=4) for RE{sub 3}M{sub 2}Ge{sub 3} (M=Ru, Ir) and monoclinic Sc{sub 2}CoSi{sub 2}-type structures (space group C2/m, Z=4) for RE{sub 2}IrGe{sub 2}. Full crystal structures were determined by single-crystal X-ray diffraction for all members of RE{sub 3}Ru{sub 2}Ge{sub 3} (a=4.2477(6) Å, b=10.7672(16) Å, c=13.894(2) Å for RE=Y; a=4.2610(3)–4.2045(8) Å, b=10.9103(8)–10.561(2) Å, c=14.0263(10)–13.639(3) Å in the progression of RE from Gd to Lu) and for Tb{sub 3}Ir{sub 2}Ge{sub 3} (a=4.2937(3) Å, b=10.4868(7) Å, c=14.2373(10) Å). Both structures can be described in terms of CrB- and ThCr{sub 2}Si{sub 2}-type slabs built from Ge-centred trigonal prisms. However, band structure calculations on Y{sub 3}Ru{sub 2}Ge{sub 3} support an alternative description for RE{sub 3}M{sub 2}Ge{sub 3} based on [M{sub 2}Ge{sub 3}] layers built from linked MGe{sub 4} tetrahedra, which emphasizes the strong M–Ge covalent bonds present. The temperature dependence of the electrical resistivity of RE{sub 3}Ru{sub 2}Ge{sub 3} generally indicates metallic behaviour but with low-temperature transitions visible for some members (RE=Gd, Tb, Dy) that are probably associated with magnetic ordering of the RE atoms. Anomalously, Y{sub 3}Ru{sub 2}Ge{sub 3} exhibits semiconductor-like behaviour of uncertain origin. Magnetic measurements on Dy{sub 3}Ru{sub 2}Ge{sub 3} reveal antiferromagnetic ordering at 3 K and several unusual field-dependent transitions suggestive of complex spin reorientation processes. - Graphical abstract: RE{sub 3}M{sub 2}Ge{sub 3} (M=Ru, Ir) adopts the Hf{sub 3}Ni{sub 2}Si{sub 3}-type structure containing slabs built up from Ge-centred trigonal prisms. - Highlights: • Crystal structures of RE{sub 3}Ru{sub 2}Ge{sub 3} (RE=Y, Gd–Tm, Lu) and Tb{sub 3}Ir{sub 2}Ge{sub 3} were determined. • Strong M–Ge covalent bonds were confirmed by band structure calculations. • Most RE{sub 3}Ru{sub 2}Ge{sub 3} members except Y{sub 3}Ru{sub 2}Ge{sub 3} exhibit metallic behaviour. • Dy{sub 3}Ru{sub 2}Ge{sub 3} displays unusual field-dependent magnetic transitions.

Oliynyk, Anton O.; Stoyko, Stanislav S.; Mar, Arthur, E-mail: arthur.mar@ualberta.ca

2013-06-15

289

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

290

TB Screening Tests  

MedlinePLUS

... website will be limited. Search Help? TB Screening Tests Share this page: Was this page helpful? Also ... by needle from a vein in your arm. Test Preparation Needed? None The Test Sample What is ...

291

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

292

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

PubMed

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

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

2014-11-01

293

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

DOE PAGESBeta

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

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

2013-06-01

294

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

SciTech Connect

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

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

2013-02-15

295

Affordable TB treatments. South.  

PubMed

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

1998-07-01

296

On the structure and magnetic properties of the series RBa 2Fe 3O 8+ x (R=La,Nd,Sm,Gd)  

NASA Astrophysics Data System (ADS)

Extensive structural, thermal, magnetic, magnetoresistive, and 57Fe Mössbauer characterization of the cubic series R 13+Ba 22+(Fe 1- ?3+Fe ?4+) 3O 8+1.5 ?2-( R3+= La3+, Nd3+, Sm3+, Gd3+) revealed a non-triperovskite distribution of Ba 2+/R 3+ ions and a thermally assisted electronic hopping process between the Fe 4+ and Fe 3+ states. The Fe-sublattice magnetism is influenced by this hopping process. The 4f sublattice is paramagnetic down to 1.2 K. The resistivity is governed by a variable-range hopping process. No magnetoresistivities were observed at lower temperatures even in fields as high as 80 kOe suggesting that the charge and the spin dynamics are uncoupled. The cell metric parameters, the concentration of Fe 4+, the oxygen excess, as well as the resistive and Mossbauer parameters can be rationalized in terms of the R 3+ ionic size. The studied physical features of these compounds are distinctly different from those of the insulating triperovskite antiferromagnets R 13+Ba 22+Fe 33+O 82-( R3+= Tb3+, Dy3+, Y3+, Ho3+) . The latter compounds are well known for the triperovskite stacking of Ba 2+ and R 3+ along the c-axis and for the absence of thermally assisted electronic hoping process. The origin of such differences among the two groups is discussed.

Elzubair, A.; Massalami, M. El; Domingues, P. H.

1999-12-01

297

LiDy(PO3)4  

PubMed Central

Single crystals of lithium dysprosium polyphosphate, LiDy(PO3)4, were prepared by the flux method. The atomic arrangement is built up by infinite (PO3)n chains extending along the b axis. Dy3+ and Li+ cations alternate in the middle of four such chains, with Dy?Li distances of 3.54?(1) and 3.48?(1)?Å. The DyO8 dodeca­hedra and LiO4 tetra­hedra deviate significantly from the ideal geometry. Both Dy and Li occupy special positions (Wyckoff position 4e, site symmetry 2). PMID:21202729

Chehimi-Moumen, Fathia; Férid, Mokhtar

2008-01-01

298

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

SciTech Connect

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

Siqueira, K.P.F.; Borges, R.M. [Departamento de Química, Universidade Federal de Ouro Preto, Campus Morro do Cruzeiro, ICEB II, Ouro Preto—MG 35400-000 (Brazil); Granado, E. [Instituto de Física “Gleb Wataghin”, UNICAMP, Campinas—SP 13083-970 (Brazil); Malard, L.M.; Paula, A.M. de; Moreira, R.L. [Departamento de Física, ICEx, Universidade Federal de Minas Gerais, C.P. 702, Belo Horizonte—MG 30123-970 (Brazil); Bittar, E.M. [Laboratório Nacional de Luz Síncrotron, C.P. 6192, 13083-970 Campinas, SP (Brazil); Dias, A., E-mail: anderson_dias@iceb.ufop.br [Departamento de Química, Universidade Federal de Ouro Preto, Campus Morro do Cruzeiro, ICEB II, Ouro Preto—MG 35400-000 (Brazil)

2013-07-15

299

RECENT ADVANCES IN BROADCAST NEWS TRANSCRIPTION D.Y. Kim, G. Evermann, ZHain, D. Mrva, S.E. Trantel;L. Wang & PC.Woodland  

E-print Network

RECENT ADVANCES IN BROADCAST NEWS TRANSCRIPTION D.Y. Kim, G. Evermann, ZHain, D. Mrva, S.E. Trantel;L. Wang & PC.Woodland Cambridge University EngineeringDept, Trumpington St., Cambridge,CB2 lPZ, U; maximum a posteriori (MAP)-style MPE (MPE-MAP) training for GD mod- elling; a complementary pan

Hain, Thomas

300

George D. Bachand Carroll-Portillo, A., and Bachand, G.D. (2009). Directed attachment of antibodies to kinesin-powered  

E-print Network

shuttles. Lab Chip 9: 1005-1010. Liu, H., Spoerke, E.D., Bachand, M., Koch, S.J., Bunker, B.C., and Bachand., Liu, J., Sasaki, D.Y., and Bunker, B.C. (2008). Assembly of polar­ oriented synthetic microtubule-486. Liu, H., Bachand, G.D., Kim, H., Hayden, C.C., and Sasaki, D.Y. (2008). Lipid nanotube formation via

301

Oriented electrophoretic deposition of GdOCl nanoplatelets.  

PubMed

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

Kort, Kenneth R; Banerjee, Sarbajit

2013-02-14

302

Investigation of ^152,153Dy  

NASA Astrophysics Data System (ADS)

152Dy is one of the most studied nuclei in the nuclear chart. Excited states in 152Dy (and 153Dy) were populated via the 124Sn(33S,Xn) reaction with the beam being delivered by the ESTU tandem accelerator at the Wright Nuclear Structure Laboratory. The New Yale Plunger Device (NYPD) was used in the SPEEDY array. Lifetimes are determined using the differential decay curve method from gamma-gamma coincidence data. First results will be presented.

Shoraka, Babak; Werner, Volker; McCutchan, Elizabeth; Ai, Ho-Chiang; Casperson, Robert J.; Casten, Rick; Heinz, Andreas; Huber, Bernhard; Luettke, Robert; Qian, Jing; Terry, Russ; Williams, Elizabeth; Winkler, Ryan

2007-10-01

303

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

SciTech Connect

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

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

2009-02-15

304

Radiative lifetimes of Tb  

SciTech Connect

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

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

2001-06-01

305

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

E-print Network

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

Paris-Sud XI, Université de

306

Ternary Dy-Er-Al magnetic refrigerants  

DOEpatents

A ternary magnetic refrigerant material comprising (Dy.sub.1-x Er.sub.x)Al.sub.2 for a magnetic refrigerator using the Joule-Brayton thermodynamic cycle spanning a temperature range from about 60K to about 10K, which can be adjusted by changing the Dy to Er ratio of the refrigerant.

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

1995-07-25

307

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

308

Smooth transition between SMM and SCM-type slow relaxing dynamics for a 1-D assemblage of {Dy(nitronyl nitroxide)2} units.  

PubMed

A model example for size effects on the dynamic susceptibility behavior is provided by the chain compound [{Dy(hfac)(3)NitPhIm(2)}Dy(hfac)(3)] (NitPhIm = 2-[4-(1-imidazole)phenyl]nitronyl nitroxide radical). The Arrhenius plot reveals two relaxation regimes attributed to SMM (Delta = 17.1 K and tau(0) = 17.5 x 10(-6) s) and SCM (Delta = 82.7 K and tau(0) = 8.8 x 10(-8) s) behaviors. The ferromagnetic exchange among the spin carriers has been established for the corresponding Gd derivative. PMID:20449309

Liu, Ruina; Li, Licun; Wang, Xiaoling; Yang, Peipei; Wang, Chao; Liao, Daizheng; Sutter, Jean-Pascal

2010-04-21

309

New orthorhombic derivative of CaCu{sub 5}-type structure: RNi{sub 4}Si compounds (R=Y, La, Ce, Sm, Gd–Ho), crystal structure and some magnetic properties  

SciTech Connect

The crystal structure of new YNi{sub 4}Si-type RNi{sub 4}Si (R=Y, La, Ce, Sm, Gd–Ho) compounds has been established using powder X-ray diffraction. The YNi{sub 4}Si structure is a new structure type, which is orthorhombic derivative of CaCu{sub 5}-type structure (space group Cmmm N 65, oC12). GdNi{sub 4}Si and DyNi{sub 4}Si compounds order ferromagnetically at 25 and 19 K, respectively whereas YNi{sub 4}Si shows antiferromagnetic nature. At 15 K, DyNi{sub 4}Si shows second antiferromagnetic-like transition. The magnetic moment of GdNi{sub 4}Si at 5 K in 50 kOe field is ?7.2 ?{sub B}/f.u. suggesting a completely ordered ferromagnetic state. The magnetocaloric effect of GdNi{sub 4}Si is calculated in terms of isothermal magnetic entropy change and it reaches the maximum value of ?12.8 J/kg K for a field change of 50 kOe near T{sub C} ?25 K. - Graphical abstract: The RNi{sub 4}Si (R=Y, La, Ce, Sm, Gd–Ho) compounds crystallize in new YNi{sub 4}Si-type structure which is orthorhombic derivative of the basic CaCu{sub 5}-type structure. GdNi{sub 4}Si and DyNi{sub 4}Si compounds show the ferromagnetic-like ordering, whereas.YNi{sub 4}Si has the antiferromagnetic nature. The GdNi{sub 4}Si demonstrates the big magnetocaloric effect near temperature of ferromagnetic ordering. The relationship between initial CaCu{sub 5}-type DyNi{sub 5} and YNi{sub 4}Si-type DyNi{sub 4}Si lattices.

Morozkin, A.V., E-mail: morozkin@general.chem.msu.ru [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Knotko, A.V. [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Yapaskurt, V.O. [Department of Petrology, Geological Faculty, Moscow State University, Leninskie Gory, Moscow 119992 (Russian Federation); Yuan, Fang; Mozharivskyj, Y. [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1 (Canada); Nirmala, R. [Indian Institute of Technology Madras, Chennai 600036 (India)

2013-12-15

310

Tunable luminescence and energy transfer process between Tb 3+ and Eu 3+ in GYAG:Bi 3+, Tb 3+, Eu 3+ phosphors  

NASA Astrophysics Data System (ADS)

A series of Eu 3+ ions co-doped (Gd 0.9Y 0.1) 3Al 5O 12:Bi 3+, Tb 3+ (GYAG) phosphors have been synthesized by means of solvothermal reaction method. The XRD pattern of GYAG phosphor sintered at 1500 °C confirms their garnet phase. The luminescence properties of these phosphors have been explored by analyzing their excitation and emission spectra along with their decay curves. The excitation spectra of the GYAG:Bi 3+, Tb 3+, Eu 3+ phosphors consists of broad bands in the shorter wavelength region due to 4f 8 ? 4f 75d 1 transition of Tb 3+ ions overlapped with 6s 2 ? 6s 16p 1 ( 1S 0 ? 3P 1) transition of Bi 3+ ions and the charge transfer band of Eu 3+-O 2-. The present phosphors exhibit green and red colors due to 5D 4 ? 7F 5 transition of Tb 3+ ions and 5D 0 ? 7F 1 transition of Eu 3+ ions, respectively. The emission was shifted from green to red color by co-doping with Eu 3+ ions, which indicate that the energy transfer probability from Tb 3+ to Eu 3+ ions are dependent strongly on the concentration of Eu 3+ ions.

Park, Jin Young; Jung, Hong Chae; Seeta Rama Raju, G.; Moon, Byung Kee; Jeong, Jung Hyun; Kim, Jung Hwan

2010-05-01

311

Formation of new compounds Ln{sub 4}Al{sub 2}O{sub 9} in the Ln{sub 2}O{sub 3}{center_dot}Al{sub 2}O{sub 3} system (Ln = La, Pr, Tb)  

SciTech Connect

The new compounds La{sub 4}Al{sub 2}O{sub 9}, Pr{sub 4}Al{sub 2}O{sub 9}, and Tb{sub 4}Al{sub 2}O{sub 9} were identified in the system 2Ln{sub 2}O{sub 3}{center_dot}Al{sub 2}O{sub 3}. X-ray powder diffraction showed that they were isomorphous with the previously characterized Ln{sub 4}Al{sub 2}O{sub 9} (Ln = Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, Y) and Ln{sub 4}Ga{sub 2}O{sub 9} (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd). La{sub 4}Al{sub 2}O{sub 9}: P2{sub 1}/c, a = 7.97 {angstrom}, b = 11.09 {angstrom}, c = 11.41 {angstrom}, {beta} = 108.8{degree}, Z = 4; Pr{sub 4}Al{sub 2}O{sub 9}: P2{sub 1}/c, a = 7.80 {angstrom}, b = 11.03 {angstrom}, c = 11.31 {angstrom}, {beta} = 109.6, Z = 4; and Tb{sub 4}Al{sub 2}O{sub 9}: P2{sub 1}/c, a = 7.40 {angstrom}, b = 10.58 {angstrom}, c = 11.16 {angstrom}, {beta} = 107.2{degree}, Z = 4. The lanthanum and praseodymium compounds were metastable phases in the Ln{sub 4}Al{sub 2}O{sub 9} systems and transformed into LaAlO{sub 3} and La{sub 2}O{sub 3}, and PrAlO{sub 3} and PrO{sub 1.83} upon prolonged heating at 1,200 C, respectively. Ln{sub 4}Al{sub 2}O{sub 9} (Ln = La,Pr) were synthesized by precipitation of Al(OH){sub 4}{sup {minus}} with Ln{sup 3+} (aq) and subsequent heating at 900 C for 10 h. Tb{sub 4}Al{sub 2}O{sub 9} required calcination at 1,200 C for 10 h. The formation of La{sub 4}Al{sub 2}O{sub 9} and Pr{sub 4}Al{sub 2}O{sub 9} was followed by TGA-DSC, which was also used to assess their thermal stability. Several other members of the above family of compounds were similarly synthesized by the new synthesis route. Particularly, for Nd{sub 4}Al{sub 2}O{sub 9} this represented a significantly improved method.

Dohrup, J.; Hoeyvald, A.; Mogensen, G.; Jacobsen, C.J.H.; Villadsen, J. [Haldor Topsoee A/S, Lyngby (Denmark). Research Labs.

1996-11-01

312

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

313

Simulation of the magnetocaloric effect in Tb nanofilms  

NASA Astrophysics Data System (ADS)

Rare-earth (RE) metals have different magnetic structures resulting from the competition between the crystal-field and exchange interactions. When a magnetic field is applied it creates a third interaction and the magnetic structures are more complicated. In thin films, it is expected that even the magnetic arrangement itself can be strongly modified. Rare-earth helimagnets such as Terbium (Tb), Holmium (Ho) and Dysprosium (Dy) represent the best candidates to evidence such finite-size effects. This finite-size effect is caused by the reduced number of atoms in the direction perpendicular to the film plane that leads to a decrease of the total magnetic exchange energy. We report this contribution to the investigation of magnetocaloric effect (MCE) of thin Terbium films in the helimagnetic temperature range, from TC = 219 K to TN = 231 K, for external fields of the order of 1 kOe. We find that for strong fields, H = 50 kOe, the adiabatic temperature change ?T near the Néel temperature is around 15 K for any thickness of Tb films. However large thickness effects are found for small values of the magnetic field. For field strength of the order of a few kOe, the thermocaloric efficiency increases significantly for ultrathin (nanomagnetic) films.

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

2014-03-01

314

Simulation of the magnetocaloric effect in Tb nanofilms  

SciTech Connect

Rare-earth (RE) metals have different magnetic structures resulting from the competition between the crystal-field and exchange interactions. When a magnetic field is applied it creates a third interaction and the magnetic structures are more complicated. In thin films, it is expected that even the magnetic arrangement itself can be strongly modified. Rare-earth helimagnets such as Terbium (Tb), Holmium (Ho) and Dysprosium (Dy) represent the best candidates to evidence such finite-size effects. This finite-size effect is caused by the reduced number of atoms in the direction perpendicular to the film plane that leads to a decrease of the total magnetic exchange energy. We report this contribution to the investigation of magnetocaloric effect (MCE) of thin Terbium films in the helimagnetic temperature range, from T{sub C} = 219 K to T{sub N} = 231 K, for external fields of the order of 1 kOe. We find that for strong fields, H = 50 kOe, the adiabatic temperature change ?T near the Néel temperature is around 15 K for any thickness of Tb films. However large thickness effects are found for small values of the magnetic field. For field strength of the order of a few kOe, the thermocaloric efficiency increases significantly for ultrathin (nanomagnetic) films.

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

2014-03-31

315

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

SciTech Connect

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

Duchene, G.; Robin, J.; Odahara, A.; Byrski, Th.; Beck, F.A.; Bednarczyk, P.; Curien, D.; Courtin, S.; Dorvaux, O.; Gall, B.; Joshi, P.; Nourreddine, A.; Pachoud, E.; Piqueras, I.; Vivien, J.P. [Institut de Recherches Subatomiques, UMR 7500, CNRS-IN2P3 et Universite Louis Pasteur, F-67037 Strasbourg Cedex 2 (France); Twin, P.J.; Cullen, D.M.; Ertueck, S.; King, S.L.; Paul, E.S. [Oliver Lodge Laboratory, University of Liverpool, P.O. Box 147, Liverpool L69 7ZE (United Kingdom)] [and others

2004-02-27

316

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

317

Multidrug-Resistant Tuberculosis (MDR TB)  

MedlinePLUS

... vaccine for TB disease called Bacille Calmette-Guérin (BCG). It is used in some countries to prevent severe forms of TB in children. However, BCG is not generally recommended in the United States ...

318

Framework of behavioral indicators for outcome evaluation of TB health promotion: a Delphi study of TB suspects and Tb patients  

PubMed Central

Background Health promotion for prevention and control of Tuberculosis (TB) is implemented worldwide because of its importance, but few reports have evaluated its impact on behavior due to a lack of standard outcome indicators. The objective of this study was to establish a framework of behavioral indicators for outcome evaluation of TB health promotion among TB suspects and patients. Methods A two-round modified Delphi method involving sixteen TB control experts was used to establish a framework of behavioral indicators for outcome evaluation of TB health promotion targeted at TB suspects and patients. Results Sixteen of seventeen invited experts in TB control (authority score of 0.91 on a 1.0 scale) participated in round 1 survey. All sixteen experts also participated in a second round survey. After two rounds of surveys and several iterations among the experts, there was consensus on a framework of indicators for measuring outcomes of TB health promotion for TB suspects and patients. For TB suspects, the experts reached consensus on 2 domains (“Healthcare seeking behavior” and “Transmission prevention”), 3 subdomains (“Seeking care after onset of TB symptoms”, “Pathways of seeking care” and “Interpersonal contact etiquette”), and 8 indicators (including among others, “Length of patient delay”). For TB patients, consensus was reached on 3 domains (“Adherence to treatment”, “Healthy lifestyle” and “Transmission prevention”), 8 subdomains (including among others, “Adherence to their medication”), and 14 indicators (including “Percentage of patients who adhered to their medication”). Operational definitions and data sources were provided for each indicator. Conclusions The findings of this study provide the basis for debate among international experts on a framework for achieving global consensus on outcome indicators for TB health promotion interventions targeted at TB patients and suspects. Such consensus will help to increase effectiveness of TB health promotion, while ensuring international comparability of outcome data. PMID:24884569

2014-01-01

319

Expression of the dystrophia muscularis (dy) recessive gene in mice  

Microsoft Academic Search

STUDIES in vitro of mutant gene expression in murine muscular dystrophy now seem to have reached an impasse. For 15 years there was only one species of dystrophic mouse1, the Bar Harbor 129 ReJ strain (denoted dy\\/dy). Then in 1970, a second strain BH WK ReJ (denoted dy2J\\/dy2J) was reported2 which was described as being similar in all histopathological respects

Roger Parsons

1974-01-01

320

Staying on Track with TB Medicine  

MedlinePLUS

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

321

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

322

Ising-axis conversion in (Tb0.5Y0.5)Cu2  

NASA Astrophysics Data System (ADS)

The so-called Ising-axis conversion is an irreversible metamagnetic transition observed in the orthorhombic antiferromagnets RCu2(R=lanthanide) in high magnetic fields applied along the hard axis of magnetization. In fields parallel to the crystallographic c-axis it converts the magnetic Ising axis from the a- to the c-direction for R=Ce, Pr, Tb and Dy. This transition is accompanied by a giant magnetostriction effect (?L/L?1%) and the new state remains stable even after switching off the field. The axis conversion process is not limited to the ordered region only and occurs also in the paramagnetic range. To study the competition between the magnetic and the quadrupolar interactions an Y-diluted system is studied. High-quality single crystals of the (Tb0.5Y0.5)Cu2 compound were grown by the Czochralski pulling technique and subjected to the specific heat, magnetization, neutron diffraction and axis-conversion experiments. The dilution of the Tb sublattice leads to weakening of the magnetic exchange, manifested by lowering of the Néel temperature from TN=54 K in pure TbCu2 to TN=30 K in (Tb0.5Y0.5)Cu2, while the magnetic ground state structure remains unchanged. The Ising-axis conversion has been studied by magnetization measurements. The c-axis-magnetization curve exhibits several metamagnetic transitions corresponding to the conversion of the easy-axis of magnetization. The temperature dependence of the critical fields is well comparable to that of the pure TbCu2. From the experiments follows that the quadrupolar interaction is the driving force of the conversion process.

Svoboda, P.; Vejpravová, J.; Doerr, M.; Rotter, M.; Hoffmann, J.-U.; Satoh, I.; Komatsubara, T.

2007-03-01

323

On the optical absorption coefficient of Gd hydride thin films: coexistence of the Gd (GdH2) and GdHx (GdH2+y) phases  

Microsoft Academic Search

Electron beam evaporated Pd-capped Gd thin films were deposited on quartz substrates and subsequently hydrided. Transmittance spectra of these bilayer systems, under unpolarized normal illumination, were obtained and used in an inversion approach from which the spectral dependence of the effective optical constants is obtained. The optical absorption coefficient of the ?-phase GdHx (with 1 < x ? 2) is

W E Vargas; D E Azofeifa; N Clark

2009-01-01

324

A multiplexed and miniaturized serological tuberculosis assay identifies antigens that discriminate maximally between TB and non-TB sera  

Microsoft Academic Search

We have developed a multiplexed and miniaturized TB serological assay with the aim of identifying (combinations of) antigens that maximally discriminate between TB and non-TB patients. It features a microarray accommodating 54 TB antigens, less than 1 ?l serum consumption and an indirect immunofluorescence detection protocol. With a panel of 20 TB and 80 non-TB sera we ranked combinations of

Miao Tong; Catharina E. Jacobi; Frans M. van de Rijke; Sjoukje Kuijper; Sjaak van de Werken; Todd L. Lowary; Cornelis H. Hokke; Ben J. Appelmelk; Nico J. D. Nagelkerke; Hans J. Tanke; Rob P. M. van Gijlswijk; Jacques Veuskens; Arend H. J. Kolk; Anton K. Raap

2005-01-01

325

Single-crystal analysis of mixed ( Ln/TbPO 4) orthophosphates  

NASA Astrophysics Data System (ADS)

Structural investigations of the mixed lanthanide orthophosphates have been carried out by means of three-dimensional single-crystal X-ray diffractometry. Each mixed orthophosphate compound crystallized in the tetragonal space group I4 1amd ( D 194h, No. 141) ( Z = 4) with lattice constants of a = 6.9449(9), 6.9647(7), 6.8003(8) and c = 6.0680(18), 6.0900(6), 5.9638(6) for 1:1(Gd/Tb)PO 4, 3:1(Gd/Tb)PO 4, and 9:1(Lu/Tb)PO 4, respectively. The final least-squares full-matrix refinements, based on 313, 310, and 283 unique reflections, yielded R-values equal to 0.023, 0.017, and 0.030, respectively. The lanthanide ions are eight-coordinated to oxygen atoms, and the resulting polyhedra are best described as two orthogonal interpenetrating tetrahedra, bis-bisphenoidal ( D 2d) geometry. Important bond distances and angles, crystal data and parameters, as well as optical and X-ray fluorescence analyses are presented.

Mullica, D. F.; Sappenfield, E. L.; Boatner, L. A.

1992-08-01

326

New cloth modeling for designing dyed patterns  

Microsoft Academic Search

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

Yuki Morimoto; Kenji Ono

2010-01-01

327

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

NASA Astrophysics Data System (ADS)

Metallic glass formation is observed in rapidly quenched quaternary DyMn6-xGe6Fex (0?x?6) alloys. The easy formation of amorphous states competes with the nucleation of ternary 1:6:6 rare earth-transition metal-metal compounds DyMn6Ge6 and DyFe6Ge6. The ribbon shaped samples were quenched and investigated by x-ray diffraction, differential scanning calorimetry, and F57e Mössbauer spectrometry. Melt-spun alloys from the series of DyMn6-xGe6Fex with x=0, 2?x?3, and x=6 do not display an amorphous state but a crystalline chemically disordered structure similar to that of TbCu7- or TbFe6Sn6-type (space group P6/mmm). Amorphous samples exhibit two crystallization steps but there is no clear evidence for a glass transition effect in the calorimetric data. The Kissinger analysis was performed to calculate the effective activation energy Ea, which is equal to 345±20 kJ/mol for amorphous DyMn5.5Ge6Fe0.5 alloy. Mössbauer spectra at 77 and 300 K consist of either magnetic sextets or quadrupolar doublets for high and low Fe content, respectively. The features reflect the dilution of Fe on crystallographic sites and the subsequent increase in topological and chemical disorder when the Mn content increases. The Miedema's semiempirical model was used to calculate the formation enthalpies of amorphous alloys (?Hform). The calculated values are consistent with experimental results. The present model allows thus to explain the better glass forming ability for the compositions with high Mn content, where ?Hform is the most negative.

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

2010-10-01

328

Crystal structures and magnetic properties of novel rare-earth copper sulfides, EuRCuS3 (R = Y, Gd Lu)  

NASA Astrophysics Data System (ADS)

Novel quaternary rare-earth copper sulfides EuRCuS3 (R = Y, Gd-Lu excluding Ho, Er) have been investigated by means of x-ray diffraction, magnetic susceptibility, magnetization, and specific heat measurements. These compounds crystallize in the Eu2CuS3-type structure for R = Y, Gd-Dy and in the KZrCuS3-type structure for R = Tm-Lu. Both EuY CuS3 and EuLuCuS3 show a ferromagnetic transition and the other EuRCuS3 compounds show a ferrimagnetic transition at around 5.0 K.

Wakeshima, Makoto; Furuuchi, Fumito; Hinatsu, Yukio

2004-08-01

329

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

SciTech Connect

We investigate the effects of slight Dy/Mn off-stoichiometry on the multiferroic behaviors of DyMnO{sub 3} (Dy{sub 1?x}Mn{sub 1+x}O{sub 3}). It is revealed that the distorted lattice structure and ferroelectric property exhibit higher stability against the Mn deficiency than the Dy deficiency. Since the electric polarization includes the contributions from the Mn-Mn and Dy-Mn interactions, the measured polarization exhibits different dependence on the Mn deficiency from that on the Dy deficiency. The present work suggests that the Dy/Mn off-stoichiometry is detrimental to the ferroelectricity, owing to the modulated spin interactions and reshuffled spin frustration.

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

2014-05-07

330

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

331

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

PubMed

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

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

2014-05-01

332

A TB Space Which is Not Katetov TB  

E-print Network

with r e / . LEMMA 6. 7/* (£?, r) is TB then for all a < CUI there is Va e z satisfying xa e Va and \\Q - Va\\ = c^. PROOF. Suppose not, that for some a, xa G KG r implies |fl — V\\ < Q)\\. Let y G {x0, x j — {xa}. We aim for the contradiction that Q — {y...} is « compact, so by Lemma 1, there is %' c ^ , ^ ' a finite subcover of P(/3 -f- 1) — {y}. Then <%' [} {V} is a finite subcover of 0 — {j}, establishing the contradiction that 0 — {y} is z compact. We assume (Û, z) is 7^; we aim towards constructing a...

Fleissner, William G.

1980-06-01

333

IL7 potential function in pulmonary TB  

Microsoft Academic Search

The study aims to find some other functions of IL-7 in control TB and screen a new host marker in small groups of TB patients and controls to identify promising markers for large- scale testing. Real-time RT-PCR is used to evaluate the stability of IL-4 and IL-7 mRNA in the presence of Actinomycin D in whole blood from active TB

F. G. Pan; Y. Y. Zhao; W. Y. Han; C. J. Sun; L. C. Lei; X. Feng; C. T. Du; S. S. Liu; S. Zhu

2011-01-01

334

Why healthcare workers are sick of TB.  

PubMed

Dr Thato Mosidi never expected to be diagnosed with tuberculosis (TB), despite widely prevalent exposure and very limited infection control measures. The life-threatening diagnosis of primary extensively drug-resistant TB (XDR-TB) came as an even greater shock. The inconvenient truth is that, rather than being protected, Dr Mosidi and thousands of her healthcare colleagues are at an increased risk of TB and especially drug-resistant TB. In this viewpoint paper we debunk the widely held false belief that healthcare workers are somehow immune to TB disease (TB-proof) and explore some of the key factors contributing to the pervasive stigmatization and subsequent non-disclosure of occupational TB. Our front-line workers are some of the first to suffer the consequences of a progressively more resistant and fatal TB epidemic, and urgent interventions are needed to ensure the safety and continued availability of these precious healthcare resources. These include the rapid development and scale-up of improved diagnostic and treatment options, strengthened infection control measures, and focused interventions to tackle stigma and discrimination in all its forms. We call our colleagues to action to protect themselves and those they care for. PMID:25809771

von Delft, Arne; Dramowski, Angela; Khosa, Celso; Kotze, Koot; Lederer, Philip; Mosidi, Thato; Peters, Jurgens A; Smith, Jonathan; van der Westhuizen, Helene-Mari; von Delft, Dalene; Willems, Bart; Bates, Matthew; Craig, Gill; Maeurer, Markus; Marais, Ben J; Mwaba, Peter; Nunes, Elizabete A; Nyirenda, Thomas; Oliver, Matt; Zumla, Alimuddin

2015-03-01

335

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

336

Magnetic structure of GdNiSn  

NASA Astrophysics Data System (ADS)

The magnetic structure of the TiNiSi-type GdNiSn compound has been studied by both 155Gd Mössbauer 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 Mössbauer work.

Lee-Hone, N. R.; Lemoine, P.; Ryan, D. H.; Vernière, A.; Malaman, B.

2013-05-01

337

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

338

Deexcitation from superdeformed bands in [sup 151]Tb and neighboring [ital A][similar to]150 nuclei  

SciTech Connect

Relative intensities of the yrast and the first excited superdeformed bands in [sup 151]Tb have been accurately measured, with the EUROGAM spectrometer. It is shown that he excited band depopulates at the same freqeuncy and spin as its identical band in the isotone [sup 152]Dy whereas the yrast band deexcites at higher rotational frequency and spin even though it is much lower in excitation energy. A classification of superdeformed bands in the [ital A][similar to]150 mass region indicates that the decay-out mechanism is strongly affected by neutron pairing correlations and the occupancy of high-[ital N] intruder orbitals.

Curien, D.; de France, G.; Beausang, C.W.; Beck, F.A.; Byrski, T.; Clarke, S.; Dagnall, P.; Duchene, G.; Flibotte, S.; Forbes, S.; Forsyth, P.D.; Haas, B.; Joyce, M.A.; Kharraja, B.; Nyako, B.M.; Schueck, C.; Simpson, J.; Theisen, C.; Twin, P.J.; Vivien, J.P.; Zolnai, L. (Centre de Recherches Nucleaires, Institut National de Physique Nucleaire et de Physique des Particules Centre National de la Recherche Scientifique/Universite Louis Pasteur, F-67037 Strasbourg CEDEX (France) Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 3BX (United Kingdom) Institute of Nuclear Research, Bem ter 18/c, H-4001 Debrecen PF51 (Hungary) Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, Institut National de Physique Nucleaire et de Physique des Particules, Centre National de la Recherche Scientifique, F-91405 Orsay (France) Science and Engineering Research Council, Daresbury Laboratory, Warrington WA4 4AD (United Kingdom))

1993-10-18

339

The N=83 nucleus149Dy from Gamow-Teller decay of its 11/2- and 1/2+ 149Ho parents  

NASA Astrophysics Data System (ADS)

A high-sensitivity ?-spectroscopic study of the149Ho ?h 11/2 and ?s 1/2 ?-decays using mass separated sources has located dominant 0+ ? 1+ GT decay strength associated with decay of paired h 11/2 protons, leading to 3 ?-states in the149Dy daughter nucleus. In their ?-decay low-lying149Dy levels characteristic of an N=83 nucleus are excited. They include the ?f 7/2, ?p 3/2, ?h 9/2 and ?p 1/2 single particle- and the ?s {1/2/-1} and ?d {3/2/-1} two-particle one-hole states, as well as the ? f 7/2 × 3- and ?f 7/2 × 2+ particle-phonon multiplets. A synopsis is given of these excitations in the N=83 isotones from149Nd to153Yb. The149Dy GT decay strength is discussed in terms of the147Tb82 and148Dy82 decays. The strength function results are also compared with independent149Ho 11/2- decay data from the literature based on total ?-ray absorption measurements.

Menegazzo, R.; Kleinheinz, P.; Collatz, R.; Güven, H.; Styczen, J.; Schardt, D.; Keller, H.; Klepper, O.; Walter, G.; Huck, A.; Marguier, G.; Blomqvist, J.

1994-03-01

340

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

341

New rare earth metal-rich indides RE14Ni 3In 3 ( RE=Sc, Y, Gd-Tm, Lu)—synthesis and crystal chemistry  

NASA Astrophysics Data System (ADS)

The rare earth-nickel-indides RE14Ni 3In 3 ( RE=Sc, Y, Gd-Tm, Lu) were synthesized from the elements by arc-melting and subsequent annealing. The compounds were investigated on the basis of X-ray powder and single crystal data: Lu 14Co 2In 3 type, P4 2/ nmc, Z=4, a=888.1(1), c=2134.7(4), wR2=0.0653, 1381 F2 values, 63 variables for Sc 13.89Ni 3.66In 2.45; a=961.2(1), c=2316.2(5), wR2=0.0633, 1741 F2 values, 64 variables for Y 13.84Ni 3.19In 2.97; a=965.3(1), c=2330.5(5), wR2=0.0620, 1765 F2 values, 63 variables for Gd 14Ni 3.29In 2.71; a=956.8(1), c=2298.4(5), wR2=0.0829, 1707 F2 values, 64 variables for Tb 13.82Ni 3.36In 2.82; a=951.7(1), c=2289.0(5), wR2=0.0838, 1794 F2 values, 64 variables for Dy 13.60Ni 3.34In 3.06; a=948.53(7), c=2270.6(1), wR2=0.1137, 1191 F2 values, 64 variables for Ho 13.35Ni 3.17In 3.48; a=943.5(1), c=2269.1(5), wR2=0.0552, 1646 F2 values, 64 variables for Er 13.53Ni 3.14In 3.33; a=938.42(7), c=2250.8(1), wR2=0.1051, 1611 F2 values, 64 variables for Tm 13.47Ni 3.28In 3.25; a=937.3(1), c=2249.6(5), wR2=0.0692, 1604 F2 values, 64 variables for Tm 13.80Ni 3.49In 2.71; and a=933.4(1), c=2263.0(5), wR2=0.0709, 1603 F2 values, 64 variables for Lu 13.94Ni 3.07In 2.99. The RE14Ni 3In 3 indides show significant Ni/In mixing on the 4 c In1 site. Except the gadolinium compound, the RE14Ni 3In 3 intermetallics also reveal RE/In mixing on the 4 c RE1 site, leading to the refined compositions. Due to the high rare earth metal content, the seven crystallographically independent RE sites have between 9 and 10 nearest RE neighbors. The RE14Ni 3In 3 structures can be described as a complex intergrowth of rare earth-based polyhedra. Both nickel sites have a distorted trigonal-prismatic rare earth coordination. An interesting feature is the In2-In2 dumb-bell at an In2-In2 distance of 304 pm (for Gd 14Ni 3.29In 2.71). The crystal chemical peculiarities of the RE14Ni 3In 3 indides are briefly discussed.

Lukachuk, Mar'yana; Galadzhun, Yaroslav V.; Zaremba, Roman I.; Dzevenko, Mariya V.; Kalychak, Yaroslav M.; Zaremba, Vasyl I.; Rodewald, Ute Ch.; Pöttgen, Rainer

2005-09-01

342

Optical properties of Dy 3+-doped phosphate and fluorophosphate glasses  

NASA Astrophysics Data System (ADS)

Optical properties of Dy 3+-doped phosphate (P 2O 5 + K 2O + BaO + Al 2O 3) and fluorophosphate (P 2O 5 + K 2O + BaO + BaF 2 + Al 2O 3) glasses have been investigated. The observed bands in absorption spectra of 1.0 mol% Dy 3+-doped glasses have been assigned and analyzed using the parametric free-ion Hamiltonian model. Judd-Ofelt (JO) intensity parameters have been obtained from the optical absorption spectra. The sensitiveness of the ?2 JO parameter to the hypersensitive transition has been demonstrated. Using these JO parameters radiative properties of some of the excited states of Dy 3+ ions have been calculated. A strong yellow emission was observed from the 4F 9/2 ? 6H 13/2 transition of Dy 3+ ions in these glasses. The peak stimulated emission cross-section for the 4F 9/2 ? 6H 13/2 transition is found to be comparable with those of other Dy 3+: systems. The decay curves of the 4F 9/2 level have been measured and are found to deviate from exponential nature with increase in Dy 3+ ions concentration. The non-exponential decay curves have been fitted with the Inokuti-Hirayama model which revealed that dipole-dipole mechanism is responsible for the energy transfer processes through Dy 3+-Dy 3+ interactions.

Babu, S. Surendra; Babu, P.; Jayasankar, C. K.; Tröster, Th.; Sievers, W.; Wortmann, G.

2009-02-01

343

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

344

Dy(3+)-doped zinc fluorophosphate glasses for white luminescence applications.  

PubMed

Dysprosium (Dy(3+)) 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 (4)F9/2 level of 1.0 mol% of Dy2O3 doped glass. Visible luminescence spectra have been obtained due to (4)F9/2?(6)HJ (J=11/2, 13/2, 15/2) transitions of Dy(3+) ions under 385 nm excitation. The yellow-to-blue luminescence intensity ratios and chromaticity coordinates of Dy(3+) ions in these glasses have been analyzed as a function of Dy(3+) ion concentration. The decay profiles for the (4)F9/2 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 Dy(3+) ion) and acceptor (ground state Dy(3+) ion). The results reveal that these glasses emit bright white light which is suitable for the development of W-LEDs. PMID:23719414

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

2013-09-01

345

Pinjia Meng1 David D.Y. Chen2  

E-print Network

Pinjia Meng1 Ning Fang2 Meng Wang3 Huwei Liu3 David D.Y. Chen2 1 Department of Forensic Science methods have been developed for different Correspondence: Dr. David D.Y. Chen, Department of Chemistry, University of British Colombia, 2036 Main Mall, Vancouver, V6T 1Z1, Canada E-mail: chen@chem.ubc.ca Fax: 1604

Chen, David D.Y.

346

Ag and Dy doped zeolite as a broadband phosphor  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

347

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

SciTech Connect

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

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

2014-01-01

348

Magnetic domain pinning in an anisotropy-engineered GdTbFe thin film  

SciTech Connect

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

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

2006-08-01

349

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

PubMed Central

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

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

1994-01-01

350

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

SciTech Connect

All TbNi{sub 2}, TbMn{sub 2}, and TbNi{sub 2}Mn compounds exhibit the cubic Laves phase with AB{sub 2}-type structure in spite of the fact that the ratio of the Tb to transition-metal components in TbNi{sub 2}Mn is 1:3. Rietveld refinement indicates that in TbNi{sub 2}Mn the Mn atoms are distributed on both the A (8a) and B (16d) sites. The values of the lattice constants were measured to be a?=?14.348?Å (space group F-43?m), 7.618?Å, and 7.158?Å (space group Fd-3?m) for TbNi{sub 2}, TbMn{sub 2}, and TbNi{sub 2}Mn, respectively. The magnetic transition temperatures T{sub C} were found to be T{sub C}?=?38?K and T{sub C}?=?148?K for TbNi{sub 2} and TbNi{sub 2}Mn, respectively, while two magnetic phase transitions are detected for TbMn{sub 2} at T{sub 1}?=?20?K and T{sub 2}?=?49?K. Clear magnetic history effects in a low magnetic field are observed in TbMn{sub 2} and TbNi{sub 2}Mn. The magnetic entropy changes have been obtained.

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

2014-05-07

351

A comparative study of magnetic behaviors in TbNi2, TbMn2 and TbNi2Mn  

NASA Astrophysics Data System (ADS)

All TbNi2, TbMn2, and TbNi2Mn compounds exhibit the cubic Laves phase with AB2-type structure in spite of the fact that the ratio of the Tb to transition-metal components in TbNi2Mn is 1:3. Rietveld refinement indicates that in TbNi2Mn the Mn atoms are distributed on both the A (8a) and B (16d) sites. The values of the lattice constants were measured to be a = 14.348 Å (space group F-43 m), 7.618 Å, and 7.158 Å (space group Fd-3 m) for TbNi2, TbMn2, and TbNi2Mn, respectively. The magnetic transition temperatures TC were found to be TC = 38 K and TC = 148 K for TbNi2 and TbNi2Mn, respectively, while two magnetic phase transitions are detected for TbMn2 at T1 = 20 K and T2 = 49 K. Clear magnetic history effects in a low magnetic field are observed in TbMn2 and TbNi2Mn. The magnetic entropy changes have been obtained.

Wang, J. L.; Md Din, M. F.; Kennedy, S. J.; Hong, F.; Campbell, S. J.; Studer, A. J.; Wu, G. H.; Cheng, Z. X.; Dou, S. X.

2014-05-01

352

Homelessness Is a Risk Factor for TB  

MedlinePLUS

... Stages & Populations Travelers' Health Workplace Safety & Health Features Media Sign up for Features Get Email Updates To ... TB cases among this high-risk population. Features Media Sign up for Features Get Email Updates To ...

353

Magnetic properties of Ni/Tb multilayers  

NASA Astrophysics Data System (ADS)

Thin multilayer films of alternating ultrathin Ni and Tb layers ( tNi=5…80 Å, tTb=30 Å) were sputter-deposited at room temperature and magnetically characterised by temperature-dependent SQUID measurements and torque measurements at T=300 K. Despite of the multilayer structure of all samples and a transition of the microstructure of the Ni layers the measured spontaneous magnetic moment of all samples is explained by a band filling model in analogy to amorphous and crystalline NiRE alloys. The magnetic Ni moment is quenched by a successive filling of its 3d minority band by the 5d, 6 s conduction electrons of Tb. As long as the Ni moment is not zero an antiferromagnetic Ni-Tb coupling and a perpendicular anisotropy component appears. The corresponding results of structural investigations are given elsewhere J. Magn. Magn. Mater. 248 (2002) 181.

Schmidt, Thomas; Hoffmann, Horst

2003-02-01

354

HIV/STD/TB PREVENTION NEWS DATABASE  

EPA Science Inventory

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

355

Observation of superdeformation in /sup 152/Dy  

SciTech Connect

High-resolution, low-background two-dimensional ..gamma..-ray energy correlations E(..gamma../sub 1/) vs E(..gamma../sub 2/) have been measured at high spin in /sup 152/Dy with the spectrometer TESSA2. Ridges characteristic of rotational behavior are observed for ..gamma..-ray energies 0.8< or =E(..gamma..)< or =1.35 MeV. The separation of the ridges gives a dynamical moment of inertia scrI/sub band//sup(/sup 2/) = (85 +- 2)h/sup 2/ MeV/sup -1/ indicating a quadrupole deformation of epsilonroughly-equal0.51 for a rigid body assuming ..gamma.. = 0.

Nyako, B.M.; Cresswell, J.R.; Forsyth, P.D.; Howe, D.; Nolan, P.J.; Riley, M.A.; Sharpey-Schafer, J.F.; Simpson, J.; Ward, N.J.; Twin, P.J.

1984-02-13

356

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 µB/Gd) and at dosage of 9.0 × 1015 cm-2 (2.6 µB/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.

357

Nuclear Structure in 146Gd  

E-print Network

In this work the experimental study of the 144Sm(alpha, 2n) fusion-evaporation reaction is presented. The experiment was carried out at the IKP of the University of Cologne in order to identify double octupole states and two-particle configurations in the 146Gd nucleus. The target was surrounded by a compact array of nine individual Ge detectors and one EUROBALL CLUSTER detector. A total of 44 new states have been identified, as well as new gamma rays corresponding to 26 previously known levels. Among these levels, new candidates for the two-particle configuration states have been found as well as for the (3- x 2+) and (3- x 3-) two phonon multiplets. A very important results of this work is the unequivocal assignment of the 6- member of the two phonon octupole state in 146Gd by identifying the E3 branching to the one phonon 3- state. This result presents the first conclusive observation of a 6+ to 3- to 0+ double E3 cascade in the decay of a two-phonon octupole state.

Luis Caballero

2010-01-19

358

A multiplexed and miniaturized serological tuberculosis assay identifies antigens that discriminate maximally between TB and non-TB sera.  

PubMed

We have developed a multiplexed and miniaturized TB serological assay with the aim of identifying (combinations of) antigens that maximally discriminate between TB and non-TB patients. It features a microarray accommodating 54 TB antigens, less than 1 microl serum consumption and an indirect immunofluorescence detection protocol. With a panel of 20 TB and 80 non-TB sera we ranked combinations of TB antigens with respect to sensitivity and specificity of TB detection by means of logistic step-forward regression analysis. The highest-ranking TB antigen combination had an area-under-the-curve of the receiver-operator-characteristics (ROC) of 0.95. We also identified an antigen that on its own provided good specificity and sensitivity of TB detection (Ara6-BSA; area-under-the-ROC curve: 0.90). These area-under-the-ROC curve values are exceptionally high for a serological TB assay. We conclude that TB antigen microarrays permit rapid identification of TB antigens that, either alone or in combination, discriminate maximally between TB and non-TB patients and that such identification provides an excellent starting point for developing point-of-care diagnostic assays. PMID:15979638

Tong, Miao; Jacobi, Catharina E; van de Rijke, Frans M; Kuijper, Sjoukje; van de Werken, Sjaak; Lowary, Todd L; Hokke, Cornelis H; Appelmelk, Ben J; Nagelkerke, Nico J D; Tanke, Hans J; van Gijlswijk, Rob P M; Veuskens, Jacques; Kolk, Arend H J; Raap, Anton K

2005-06-01

359

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

360

TheugsofWar TIM BON YH DY & NIGEL LENDON  

E-print Network

TheugsofWar TIM BON YH DY & NIGEL LENDON #12;The ugs of War #12;TThhee RRuuggss ooff WWaarr iiss for Indigenous Australia HRC, Humanities Research Centre NIH, the National Institute of the Humanities NIAP

Botea, Adi

361

Probing the Structure-Relaxivity Relationship of Bis-hydrated Gd(DOTAla) Derivatives.  

PubMed

Two structural isomers of the heptadentate chelator DO3Ala were synthesized, with carboxymethyl groups at either the 1,4- or 1,7-positions of the cyclen macrocycle. To interrogate the relaxivity under different rotatational dynamics regimes, the pendant primary amine was coupled to ibuprofen to enable binding to serum albumin. These chelators 6a and 6b form bis(aqua) ternary complexes with Gd(III) or Tb(III) as estimated from relaxivity measurements or luminescence lifetime measurements in water. The relaxivity of [Gd(6a)(H2O)2] and [Gd(6b)(H2O)2] was measured in the presence and absence of coordinating anions prevalent in vivo such as phosphate, lactate, and bicarbonate and compared with data attained for the q = 2 complex [Gd(DO3A)(H2O)2]. We found that relaxivity was reduced through formation of ternary complexes with lactate and bicarbonate, albeit to a lesser degree then the relaxivity of Gd(DO3A). In the presence of 100-fold excess phosphate, relaxivity was slightly increased and typical for q = 2 complexes of this size (8.3 mM(-1) s(-1) and 9.5 mM(-1) s(-1), respectively, at 37 °C, 60 MHz). Relaxivity for the complexes in the presence of HSA corresponded well to relaxivity obtained for complexes with reduced access for inner-sphere water (13.5 and 12.7 mM(-1) s(-1) at 37 °C, 60 MHz). Mean water residency time at 37 °C was determined using temperature-dependent (17)O-T2 measurements at 11.7 T and calculated to be (310)?M = 23 ± 1 ns for both structural isomers. Kinetic inertness under forcing conditions (pH 3, competing DTPA ligand) was found to be comparable to [Gd(DO3A)(H2O)]. Overall, we found that the replacement of one of the acetate arms of DO3A with an amino-propionate arm does not significantly alter the relaxometric and kinetic inertness properties of the corresponding Gd complexes; however, it does provide access to easily functionalizable q = 2 derivatives. PMID:25693053

Boros, Eszter; Caravan, Peter

2015-03-01

362

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?vá?, 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

363

Hetero-tri-spin [2p-3d-4f] chain compounds based on nitronyl nitroxide lanthanide metallo-ligands: synthesis, structure, and magnetic properties.  

PubMed

Employing nitronyl nitroxide lanthanide(III) complexes as metallo-ligands allowed the efficient and highly selective preparation of three series of unprecedented hetero-tri-spin (Cu-Ln-radical) one-dimensional compounds. These 2p-3d-4f spin systems, namely [Ln3Cu(hfac)11(NitPhOAll)4] (Ln(III) = Gd 1Gd, Tb 1Tb, Dy 1Dy; NitPhOAll = 2-(4'-allyloxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide), [Ln3Cu(hfac)11(NitPhOPr)4] (Ln(III) = Gd 2Gd, Tb 2Tb, Dy 2Dy, Ho 2Ho, Yb 2Yb; NitPhOPr = 2-(4'-propoxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) and [Ln3Cu(hfac)11(NitPhOBz)4] (Ln(III) = Gd 3Gd, Tb 3Tb, Dy 3Dy; NitPhOBz=2-(4'-benzyloxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) involve O-bound nitronyl nitroxide radicals as bridging ligands in chain structures with a [Cu-Nit-Ln-Nit-Ln-Nit-Ln-Nit] repeating unit. The dc magnetic studies show that ferromagnetic metal-radical interactions take place in these hetero-tri-spin chain complexes, these and the next-neighbor interactions have been quantified for the Gd derivatives. Complexes 1Tb and 2Tb exhibit frequency dependence of ac magnetic susceptibilities, indicating single-chain magnet behavior. PMID:25169024

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

2014-10-01

364

(BMI)3LnCl6 crystals as models for the coordination environment of LnCl3 (Ln = Sm, Eu, Dy, Er, Yb) in 1-butyl-3-methylimidazolium chloride ionic-liquid solution.  

PubMed

A series of (BMI)3LnCl6 (Ln = Sm, Eu, Dy, Er, Yb) crystals was prepared from solutions of LnCl3 dissolved in the ionic liquid, 1-butyl-3-methylimidazolium chloride (BMICl). Crystals with Ln = 5% Sm + 95% Gd and with Ln = 5% Dy + 95% Gd were also grown to assess the importance of cross-relaxation in the Sm and Dy samples. The crystals are isostructural, with monoclinic space group P21/c and four formula units per unit cell. The first coordination sphere of Ln(3+) consists of six Cl(-) anions forming a slightly distorted octahedral LnCl6(3-) center. The second coordination sphere is composed of nine BMI(+) cations. The emission spectra and luminescence lifetimes of both (BMI)3LnCl6 crystals and LnCl3 in BMICl solution were measured. The spectroscopic similarities suggest that crystalline (BMI)3LnCl6 provides a good model of the Ln(3+) coordination environment in BMICl solution. PMID:24849287

Han, Yulun; Lin, Cuikun; Meng, Qingguo; Dai, Fengrong; Sykes, Andrew G; Berry, Mary T; May, P Stanley

2014-06-01

365

Constraint on 0??? matrix elements from a novel decay channel of the scissors mode: the case of 154Gd.  

PubMed

The nucleus (154)Gd is located in a region of the nuclear chart where rapid changes of nuclear deformation occur as a function of particle number. It was investigated using a combination of ?-ray scattering experiments and a ??-coincidence study following electron capture decay of (154)Tb(m). A novel decay channel from the scissors mode to the first excited 0(+) state was observed. Its transition strength was determined to B(M1;1(sc)(+)?0(2)(+))=0.031(4)?(N)(2). The properties of the scissors mode of (154)Gd imply a much larger matrix element than previously thought for the neutrinoless double-? decay to the 0(2)(+) state in such a shape-transitional region. Theory indicates an even larger effect for (150)Nd. PMID:24206482

Beller, J; Pietralla, N; Barea, J; Elvers, M; Endres, J; Fransen, C; Kotila, J; Möller, O; Richter, A; Rodríguez, T R; Romig, C; Savran, D; Scheck, M; Schnorrenberger, L; Sonnabend, K; Werner, V; Zilges, A; Zweidinger, M

2013-10-25

366

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

367

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

PubMed Central

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

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

2014-01-01

368

If I Had - Recurring Cough and Positive TB Test  

MedlinePLUS

... to Sudden Infant Death If I Had - Recurring Cough and Positive TB Test - Dr. Masae Kawamura, MD, ... Back to Home Page If I Had - Recurring Cough and Positive TB Test - Dr. Masae Kawamura, MD, ...

369

HIV-1 and the immune response to TB  

PubMed Central

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

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

2013-01-01

370

Tuberculosis: Learn the Signs and Symptoms of TB Disease  

MedlinePLUS

... Stages & Populations Travelers' Health Workplace Safety & Health Features Media Sign up for Features Get Email Updates To ... TB Personal Stories State TB Control Offices Features Media Sign up for Features Get Email Updates To ...

371

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

NASA Technical Reports Server (NTRS)

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

Eldridge, Jeffrey I.; Chambers, Matthew D.

2012-01-01

372

TB-02787-001_v01 i November 2006  

E-print Network

TB-02787-001_v01 i November 2006 TB-02787-001_v0.9 Technical Brief NVIDIA GeForce 8800 GPU Quality #12;NVIDIA GeForce 8800 Architecture Technical Brief ii TB-02787-001_v1.0 November 8, 2006 #12;GeForce ..................................................................................................... 38 TB-02787-001_v1.0 iii November 8, 2006 #12;NVIDIA GeForce 8800 Architecture Technical Brief Direct

Agrawal, Gagan

373

TB-02787-001_v01 i November 2006  

E-print Network

TB-02787-001_v01 i November 2006 TB-02787-001_v01 Technical Brief NVIDIA GeForce 8800 GPU Quality #12;NVIDIA GeForce 8800 Architecture Technical Brief ii TB-02787-001_v01 November 8, 2006 #12;GeForce .................................................................................... 39 TB-02787-001_v01 iii November 8, 2006 #12;NVIDIA GeForce 8800 Architecture Technical Brief Stream

Koppelman, David M.

374

GAPS IN THE GD-1 STAR STREAM  

SciTech Connect

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

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

2013-05-10

375

Magnetoresistance of Gd doped Carbon films  

NASA Astrophysics Data System (ADS)

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

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

2007-03-01

376

Moxifloxacin Prophylaxis against MDR TB, New York, New York, USA.  

PubMed

Contacts of persons infected with multidrug-resistant tuberculosis (MDR TB) have few prophylaxis options. Of 50 contacts of HIV- and MDR TB-positive persons who were treated with moxifloxacin, 30 completed treatment and 3 discontinued treatment because of gastrointestinal symptoms. Moxifloxacin was generally well-tolerated; further research of its efficacy against MDR TB is needed. PMID:25695482

Trieu, Lisa; Proops, Douglas C; Ahuja, Shama D

2015-03-01

377

Moxifloxacin Prophylaxis against MDR TB, New York, New York, USA  

PubMed Central

Contacts of persons infected with multidrug-resistant tuberculosis (MDR TB) have few prophylaxis options. Of 50 contacts of HIV- and MDR TB–positive persons who were treated with moxifloxacin, 30 completed treatment and 3 discontinued treatment because of gastrointestinal symptoms. Moxifloxacin was generally well-tolerated; further research of its efficacy against MDR TB is needed. PMID:25695482

Proops, Douglas C.; Ahuja, Shama D.

2015-01-01

378

Self-assembly synthesis, structural features, and photophysical properties of dilanthanide complexes derived from a novel amide type ligand: energy transfer from Tb(III) to Eu(III) in a heterodinuclear derivative.  

PubMed

A novel amide type ligand benzyl-N,N-bis[(2'-furfurylaminoformyl)phenoxyl)ethyl]-amine (L) has been designed and applied for the self-assembly generation of homodinuclear lanthanide coordination compounds [Ln2(?2-L)2(NO3)6(EtOH)2] [Ln = Eu (1), Tb (2), and Gd (3)] and a heterodinuclear derivative [EuTb(?2-L)2(NO3)6(EtOH)2] (4). All the complexes have been characterized by the X-ray single-crystal diffraction analyses. They are isostructural, crystallize in a monoclinic space group P21/c, and form [2 + 2] rectangular macrocycle structures. Compound 4 is the first example of a [2 + 2] rectangular macrocycle heterodinuclear EuTb complex assembled from an amide type ligand. In 4, the discrete 0D dimeric [EuTb(?2-L)2(NO3)6(EtOH)2] units are extended, via the multiple N-H···O hydrogen bonds, into a 2D supramolecular network that has been topologically classified as a uninodal 4-connected underlying net with the sql [Shubnikov tetragonal plane net] topology. The triplet state ((3)??*) of L studied by the Gd(III) complex 3 demonstrated that the ligand beautifully populates Tb(III) emission (? = 52%), whereas the corresponding Eu(III) derivative 1 shows weak luminescence efficiency (? = 0.7%) because the triplet state of L has a poor match with (5)D1 energy level of Eu(III). Furthermore, the photoluminescent properties of heterodinuclear complex 4 have been compared with those of the analogous homodinuclear compounds. The quantum yield and lifetime measurements prove that energy transfer from Tb(III) to Eu(III) is being achieved, namely, that the Tb(III) center is also acting to sensitize the Eu(III) and enhancing Eu(III) emission in 4. PMID:24401003

Gao, Cunji; Kirillov, Alexander M; Dou, Wei; Tang, Xiaoliang; Liu, Liangliang; Yan, Xuhuan; Xie, Yujie; Zang, Peixian; Liu, Weisheng; Tang, Yu

2014-01-21

379

Boeing TB-29 Superfortress (B-29)  

NASA Technical Reports Server (NTRS)

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

1945-01-01

380

ANL/APS/TB53 Insertion Devices  

E-print Network

is the calibration system [4]. This system consists of the calibration electromagnet and a set of Nuclear Magnetic moments of individual permanent magnets [5]. ID Magnetic Specifications An electron beam passing throughANL/APS/TB53 Insertion Devices: Magnetic Measurements and Tuning I. Vasserman, E. Gluskin, J

Kemner, Ken

381

Influence of the rare earth concentration on the crystallization process of Fe-Dy-B amorphous alloys. Study of Fe74Dy6B20 and Fe70Dy10B20 alloys  

NASA Astrophysics Data System (ADS)

The crystallization behaviour of Fe74 Dy6 B20 and Fe70 Dy10 B20 amorphous alloys was carefully investigated by differential scanning calorimetry, Mössbauer spectrometry and x-ray diffraction up to 800 °C. Calorimetric studies were performed in limited temperature ranges that were progressively extended. For Fe74 Dy6 B20 , after partial crystallization into the tetragonal Fe3 B compound, the remaining amorphous part segregates into two amorphous `phases', respectively enriched and impoverished in dysprosium. Tetragonal Fe3 B further transforms into orthorhombic Fe3 B. Metastable Dy3 Fe62 B14 compound then forms from the Dy-impoverished amorphous fraction, and subsequent crystallization of the Dy1 + icons/Journals/Common/varepsilon" ALT="varepsilon" ALIGN="MIDDLE"/> Fe4 B4 phase occurs in the Dy-enriched fraction. Finally, Dy3 Fe62 B14 decomposes into bcc iron, Dy1 + icons/Journals/Common/varepsilon" ALT="varepsilon" ALIGN="MIDDLE"/> Fe4 B4 and iron borides. The nature of the first crystallization product suggests the existence of local environments of t-Fe3 B type for this Dy concentration. The crystallization process of Fe70 Dy10 B20 strongly differs from that of Fe74 Dy6 B20 . Segregation phenomena occur in the amorphous state prior to any crystallization. If the nature of the first crystallization product is assumed to be correlated with short-range order in the amorphous state, our results suggest that the local environments differ from those of Fe74 Dy6 B20 , as they probably involve dysprosium atoms. This behaviour would agree with a previous Mössbauer study performed on the as-quenched amorphous alloys, providing evidence for a structural modification of the iron environments in the rare earth concentration range 8-9 at.%.

Ravach, G.; Machizaud, F.; Teillet, J.; LeBreton, J. M.; Fnidiki, A.

2000-04-01

382

Ferroelectricity and Giant Magnetocapacitance in Perovskite Rare-Earth Manganites  

Microsoft Academic Search

The relationships among magnetism, lattice modulation, and dielectric properties have been investigated for RMnO3 (R=Eu, Gd, Tb, and Dy). These compounds show a transition to an incommensurate lattice structure below their Néel temperature, and subsequently undergo an incommensurate-commensurate (IC-C) phase transition. For TbMnO3 and DyMnO3 it was found that the IC-C transition is accompanied by a ferroelectric transition, associated with

T. Goto; T. Kimura; G. Lawes; A. P. Ramirez; Y. Tokura

2004-01-01

383

Fluorescence dynamics of Tb 3+ and Tb 3+/Ho 3+ doped phosphate glasses  

NASA Astrophysics Data System (ADS)

UV absorption and fluorescence analysis of Tb 3+ in phosphate glass is carried out by Judd-Ofelt method with emphasis on the 5D?7F lasing transition. Branching ratios, peak emission cross-sections for 5D?7( level of Tb 3+ are calculated using Judd-Ofelt intensity parameters. Furthermore, fluorescence dynamics of the 5D level of Tb 3+ ion in phosphate glasses co-doped with Ho 3+ were experimentally investigated with classical Forster-Dexter model for direct cross-relaxation type energy transfer between Tb 3+ (donor) and Ho 3+ (acceptor). The energy transfer rates between Tb 3+ and Ho 3+ in phosphate glasses were calculated on the basis of experimental measurements. These measurements were performed for 1 wt.% of Tb 3+ and Ho 3+ concentration ranging from 0 to 3 wt.%. The results show that energy transfer occurs between the 5D 4 terbium and 5F 3 holmium levels and is a phonon-assisted dipole-dipole interaction.

Rai, S.; Hazarika, S.

2008-05-01

384

Reinvestigation of the Cd–Gd phase diagram  

PubMed Central

The complete Cd–Gd equilibrium phase diagram was investigated by a combination of powder-XRD, SEM and DTA. All previously reported phases, i.e., CdGd, Cd2Gd, Cd3Gd, Cd45Gd11, Cd58Gd13, and Cd6Gd, could be confirmed. In addition, a new intermetallic compound with a stoichiometric composition corresponding to “Cd8Gd” was found to exist. It was obtained that “Cd8Gd” decomposes peritectically at 465 °C. Homogeneity ranges of all intermetallic compounds were determined at distinct temperatures. In addition, the maximum solubilities of Cd in the low- and high-temperature modifications of Gd were determined precisely as 4.6 and 22.6 at.%, respectively. All invariant reaction temperatures (with the exception of the formation of Cd58Gd13) as well as liquidus temperatures were determined, most probably, Cd58Gd13 is formed in a peritectoid reaction from Cd45Gd11 and Cd6Gd at a temperature below 700 °C. PMID:25544803

Reichmann, Thomas L.; Ipser, Herbert

2014-01-01

385

Gd(III)-nanodiamond conjugates for MRI contrast enhancement  

PubMed Central

A Gd(III)-nanodiamond conjugate [Gd(III)-ND] was prepared and characterized, enabling detection of nanodiamonds by MR imaging. The Gd(III)-ND particles significantly reduced the T1 of water protons with a per-Gd(III) relaxivity of 58.82 ± 1.18 mM?1s?1 at 1.5 Tesla (60 MHz). This represents a tenfold increase compared to the monomer Gd(III) complex (r1 = 5.42 ± 0.20 mM?1s?1) and is among the highest per-Gd(III) relaxivities reported. PMID:20038088

Manus, Lisa M.; Mastarone, Daniel J.; Waters, Emily A.; Zhang, Xue-Qing; Schultz-Sikma, Elise A.; MacRenaris, Keith W.; Ho, Dean

2010-01-01

386

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

387

Use of a multiple choice questionnaire to stimulate TB officers to read the TB manual in Malawi.  

PubMed

Forty-four tuberculosis (TB) officers who attended the National TB Seminar were given a multiple choice questionnaire (MCQ), based on information in the TB manual. They were asked to complete the MCQ in their hospitals, using the manual, and return it within 6 weeks to the Central Unit. Thirty-one (70%) officers returned completed MCQs. There was negative marking for incorrect answers. The mean mark was 69%. Twelve (39%) officers scored 80% or higher and four (13%) scored below 50%. MCQ assessments may be a useful way of stimulating TB officers to read TB manuals and other guidelines. PMID:15137541

Salaniponi, F M; Kwanjana, J H; Gondwe, M K; Harries, A D

2004-05-01

388

Luminescence during Tb-ion implantation into sapphire  

SciTech Connect

A study has been made of the luminescence during Tb-ion implantation in Al{sub 2}O{sub 3} or by Ar- or He-ions bombardment to Tb-ion implanted Al{sub 2}O{sub 3}. The substrates used were colorless and transparent single crystal {alpha}{minus}Al{sub 2}O{sub 3} with (0001) or (1102) surface orientation. Ion implantations of Tb-ions in Al{sub 2}O{sub 3} were carried out at fluences of 1 {times} 10{sup 13} to 1 {times} 10{sup 17} Tb/cm{sup 2} at 100 keV at nearly room temperature. Change in color of Al{sub 2}O{sub 3} substrates by Tb implantation was invisible to the naked eye. The luminescence spectra were measured by Ar (100 keV) or He (50 keV) bombardment to Tb implanted Al{sub 2}O{sub 3} or during Tb implantation into Al{sub 2}O{sub 3} using a spectroscopy with three optical filters and photomultiplier. The luminescence spectra during Tb implantation into Al{sub 2}O{sub 3} have four clear peaks identified as emission due to D-F transitions of Tb{sup 3+} state. The luminescence spectra of Tb implanted Al{sub 2}O{sub 3} excited by He, Ar and Tb bombardment were almost the same except for the luminescence at the wavelength ranging from 300 to 450 nm, which is caused by strong emission from Al{sub 2}O{sub 3} itself. The peak of the luminescence appears at 550 nm, and its intensity depends on the Tb dose. The maximum intensity of luminescence during Tb implantation at room temperature is obtained as the maximum atomic ratio of implanted Tb is 2--3 atomic %.

Kumagai, Makoto [Saitama Univ., Urawa, Saitama (Japan); Iwaki, Masaya [Inst. of Physical and Chemical Research, Wako, Saitama (Japan)

1995-12-31

389

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

390

Direct measurement of the magnetocaloric effect of microstructured Gd eutectic compounds using a new fast automatic device  

NASA Astrophysics Data System (ADS)

A newly designed experimental device for direct measurement of the magnetocaloric effect has been assembled and tested. Details about calibration and preliminary measurements performed on Gd as a standard reference material are reported together with results concerning the magnetocaloric effect of three different Gd eutectic compositions (Gd-Gd 7Pd 3, Gd-GdZn, Gd-GdCd).

Canepa, Fabio; Cirafici, Salvino; Napoletano, Myrta; Ciccarelli, Carlo; Belfortini, Claudio

2005-01-01

391

New TB treatments hiding in plain sight  

PubMed Central

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

Olive, Andrew J; Sassetti, Christopher M

2015-01-01

392

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

SciTech Connect

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

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

2012-12-15

393

[Present and future perspectives for the rapid molecular diagnosis of TB and MDR-TB].  

PubMed

Tuberculosis is still one of the diseases with a major medical and social impact, and in terms of early diagnosis (which would imply a fair treatment and established at the time), difficulties related to the delay bacilli isolation in culture, decreased susceptibility testing methods to antituberculosis drugs, lack of methods for differentiation of M. Tuberculosis complex germs of non-TB Mycobacteria, may have important clinical implications. Traditional testing of anti-TB drug susceptibility on solid Löwenstein-Jensen medium (gold standard) or liquid media can only be performed using grown samples. Determining the time it takes up to 42 days on solid media and 12 days for liquid media. For MDR/XDR TB cases itis absolutely essential to reduce the detection time. In these cases rapid diagnostic methods prove their usefulness. Automatic testing in liquid medium, molecular hybridization methods are currently recommended by the current WHO guidelines. Rapid diagnosis of MDR-TBis extremely useful for the early establishment of an effective treatment tailored more accurately on the spectrum of sensitivity of the resistant strain (thus reducing the risk of developing additional resistance to other drugs) and control the spread of these strains. Genetic diagnostic methods, approved and recommended by the WHO, can reduce the time of diagnosis of TB case and, importantly, the case of MDR-TB. They do not replace the current standard diagnostic methods and resistance profile, but complete them in selected cases. PMID:24734352

Tanasescu, Mihaela; Didilescu, Cristian; Marica, Constantin

2013-01-01

394

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

SciTech Connect

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

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

2011-02-15

395

Using polyvinyl chloride dyed with bromocresol purple in radiation dosimetry  

Microsoft Academic Search

Polyvinyl chloride (PVC) dyed with bromocresol purple was investigated as a high-dose radiation dosimeter. The absorbance at 417nm depends linearly on the dose below 50kGy. The response depends neither on dose rate nor on the irradiation temperature. The effects of post-irradiation storage in the dark and in indirect sunlight are also discussed.

Munzer Kattan; Haroun al Kassiri; Yarob Daher

2011-01-01

396

Using polyvinyl chloride dyed with bromocresol purple in radiation dosimetry.  

PubMed

Polyvinyl chloride (PVC) dyed with bromocresol purple was investigated as a high-dose radiation dosimeter. The absorbance at 417 nm depends linearly on the dose below 50 kGy. The response depends neither on dose rate nor on the irradiation temperature. The effects of post-irradiation storage in the dark and in indirect sunlight are also discussed. PMID:21109445

Kattan, Munzer; al Kassiri, Haroun; Daher, Yarob

2011-02-01

397

Synchrotron x-ray diffraction studies of the lattice and magnetic structure of epitaxial Dy films in LaF3\\/Dy\\/LaF3 sandwiches (abstract)  

Microsoft Academic Search

Lattice and magnetic x-ray diffraction from a 2000 A? thick film of Dy, sandwiched by LaF3 films on a GaAs(111) substrate, are reported. The structure was grown by molecular beam epitaxy with the c axis of the Dy parallel to the LaF3c axis and GaAs [111] axis. We find that the c-axis lattice constant of the Dy has a similar

R. F. C. Farrow; M. F. Toney; B. D. Hermsmeier; S. S. P. Parkin; D. G. Wiesler

1991-01-01

398

Synchrotron x-ray diffraction studies of the lattice and magnetic structure of epitaxial Dy films in LaF3\\/Dy\\/LaF3 sandwiches  

Microsoft Academic Search

Lattice and magnetic x-ray diffraction from a 2000 A? thick film of Dy, sandwiched by LaF3 films on a GaAs(111) substrate, are reported. The structure was grown by molecular beam epitaxy with the c axis of the Dy parallel to the LaF3c axis and GaAs [111] axis. We find that the c-axis lattice constant of the Dy has a similar

R. F. C. Farrow; M. F. Toney; B. D. Hermsmeier; S. S. P. Parkin; D. G. Wiesler

1991-01-01

399

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

SciTech Connect

Graphical abstract: Packing diagram of (a) hexagonal Dy(OH){sub 3} and (b) cubic Dy{sub 2}O{sub 3} nanorods. Highlights: ? Hexagonal Dy(OH){sub 3} and Dy{sub 2}O{sub 3} nanorods were prepared by hydrothermal route. ? Phase dependent PL and TL studies were carried out. ? The kinetic parameters such as activation energy (E), order of kinetics (b), and frequency factor (s) were estimated using peak shape method. ? Linear response of cubic Dy{sub 2}O{sub 3} phase is useful for its application in dosimetry. -- Abstract: Hexagonal Dy(OH){sub 3} and cubic Dy{sub 2}O{sub 3} nanorods were prepared by hydrothermal method. Dy(OH){sub 3} nanorods was directly obtained at 180 °C for 20 h after hydrothermal treatment whereas subsequently heat treatment at 750 °C for 2 h gives pure cubic Dy{sub 2}O{sub 3}. SEM micrographs reveal that needle shaped rods with different sizes were observed in both the phases. TEM results also confirm this. The TL response of hexagonal Dy(OH){sub 3} and cubic Dy{sub 2}O{sub 3} nanorods have been analyzed for ?-irradiation over a wide range of exposures (1–5 kGy). TL glow peak intensity increases with ? dose in both the phases. The activation energy (E), order of kinetics (b), and frequency factor (s) for both the phases have been determined using Chen's peak shape method. The simple glow curve shape, structure and linear response to ?-irradiation over a large span of exposures makes the cubic Dy{sub 2}O{sub 3} as a useful dosimetric material to estimate high exposures of ?-rays.

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

2012-08-15

400

Photoluminescence and energy transfer study of Er3+ and Dy3+ codoped tellurite glasses.  

PubMed

Photoluminescence properties of the Er(3+)-Dy3+ codoped tellurite glasses were studied by absorption and visible emission spectra, which revealed luminescence bands of both Er3+ and Dy3+ when pumping with the wavelength of 325 nm. The concentration quenching occurred as Dy3+ concentration increased beyond 3 mol%. The dependence of Er3+ characteristic emission on Dy3+ concentration indicated energy transfer process between Er3+ and Dy3+. The chromaticity coordinates of these glasses are close to white light, which implies that these glasses might be potential candidates for white lighting through an appropriate combination. PMID:22409022

Zhang, Feng; Xiao, Zhisong; Zhu, Fang; Yan, Lu; Zhou, Bo; Huang, Anping

2011-12-01

401

A Measurement of the Electron edm using GdIG  

Microsoft Academic Search

A measurement of the electron electric dipole moment (edm) using gadolinium iron garnet (GdIG) will be discussed. GdIG is a soft magnetic dielectric with a strong temperature -dependent contribution to its magnetization from paramagnetic gadolinium ions. Near liquid nitrogen temperatures, the Gd spins become substantially aligned when the sample is placed in a strong magnetic field. An edm of the

Larry Hunter; Noah Charney; Joel Gordon; Steve Peck; Oliver Elliott; Margaret McKeon; Steve Lamoreaux

2003-01-01

402

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

SciTech Connect

The Nd-Fe-B (t{sub NFB}?=?30?nm)/[Dy (t{sub Dy} nm)/Nd (t{sub Nd} nm)] (t{sub Dy/Nd}?=?20?nm) (thickness t{sub Dy}?=?0–10?nm) thin films were deposited on Al{sub 2}O{sub 3}(0001) substrate and subsequently in-situ annealed at 470?°C. As-deposited Nd-Fe-B thin films with a highly perpendicular orientation of c-axis were deposited by introducing bcc-Mo(111) single crystal buffer layer. After post-annealing, the grain size of the Nd-Fe-B/Dy/Nd thin films with the t{sub Dy}?=?10?nm and t{sub Nd}?=?10?nm becomes large due to the Dy and the Nd atoms thermal diffusion, while DyFe{sub 2} and Dy oxide compounds are formed in Nd-Fe-B layers, which is confirmed by means of a combination of atomic force microscopy observation and X-ray diffraction measurement. The H{sub c} of Nd-Fe-B/Dy/Nd thin films with the t{sub Dy}?=?10?nm and t{sub Nd}?=?10?nm was approximately the same value of the Nd-Fe-B thin films without Dy/Nd double layer annealed at 470?°C. On the other hand, H{sub c} is enhanced to be about 22.1?kOe in the annealed Nd-Fe-B/Dy/Nd films with the t{sub Dy}?=?0.8?nm and t{sub Nd}?=?19.2?nm.

Koike, K., E-mail: kkoike@yz.yamagata-u.ac.jp; Umezawa, J.; Ishikawa, H.; Ogawa, D.; Mizuno, Y.; Kato, H. [Department of Applied Mathematics and Physics, Yamagata University, Yonezawa 992-8510 (Japan); Miyazaki, T.; Ando, Y. [Department of Applied Physics, Tohoku University, Sendai, 980-8579 (Japan)

2014-05-07