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Sample records for earths tb dy

  1. Effect of Rare Earth Elements Burning Loss on Microstructure and Properties in TbDyFe

    Directory of Open Access Journals (Sweden)

    DENG Zhong-hua

    2016-08-01

    Full Text Available In order to simulate low vacuum experimental environment,Tb0.27Dy0.73Fe1.91 alloy round bars were prepared through melting with Tb, Dy and Fe elements, directional solidification and heat treatment in low vacuum environment. The magnetostriction of the alloy rods was tested. The microstructures and the causes of defects in the alloy were investigated. The results indicate that under the low vacuum experimental environment, there are plenty of twin dendritic lamellar microstructures and ordinary twin microstructures are generated in alloy, among which the mechanical properties and "jump" effect of twin dendritic lamellar structures are good, while the ordinary twins are bad to the magnetostrictive property in the alloy. REFe2 and REFe3 coupling phase is the main phase in the matrix, the burning loss of rare earth elements lead variations in chemical composition, resulting coupling growth with REFe3 phase and REFe2 phase. The thermal stress and the burning loss of rare earth elements segregate at grain boundaries resulting in the presence of micro-cracks and micro-holes. These microstructures and defects generate bad impact on mechanical properties and magnetostriction of TbDyFe alloy rods.

  2. Raman spectroscopy of rare-earth orthoferrites R FeO3 (R =La, Sm, Eu, Gd, Tb, Dy)

    Science.gov (United States)

    Weber, Mads Christof; Guennou, Mael; Zhao, Hong Jian; Íñiguez, Jorge; Vilarinho, Rui; Almeida, Abílio; Moreira, Joaquim Agostinho; Kreisel, Jens

    2016-12-01

    We report a Raman scattering study of six rare-earth orthoferrites R FeO3, with R = La, Sm, Eu, Gd, Tb, Dy. The use of extensive polarized Raman scattering of SmFeO3 and first-principles calculations enable the assignment of the observed phonon modes to vibrational symmetries and atomic displacements. The assignment of the spectra and their comparison throughout the whole series allow correlating the phonon modes with the orthorhombic structural distortions of R FeO3 perovskites. In particular, the positions of two specific A g modes scale linearly with the two FeO6 octahedra tilt angles, allowing the distortion to be tracked throughout the series. At variance with literature, we find that the two octahedra tilt angles scale differently with the vibration frequencies of their respective A g modes. This behavior, as well as the general relations between the tilt angles, the frequencies of the associated modes, and the ionic radii are rationalized in a simple Landau model. The reported Raman spectra and associated phonon-mode assignment provide reference data for structural investigations of the whole series of orthoferrites.

  3. Effect of Tb and Al substitution within the rare earth and cobalt sublattices on magnetothermal properties of Dy0.5Ho0.5Co2

    Science.gov (United States)

    Chzhan, V. B.; Tereshina, E. A.; Mikhailova, A. B.; Politova, G. A.; Tereshina, I. S.; Kozlov, V. I.; Ćwik, J.; Nenkov, K.; Alekseeva, O. A.; Filimonov, A. V.

    2017-06-01

    The effect of Tb and Al substitution within the rare earth and cobalt sublattices on structural and magnetothermal properties of Dy0.5Ho0.5Co2 has been studied. Multicomponent Laves phase alloys Tbx(Dy0.5Ho0.5)1-xCo2-yAly (x = 0, 0.3, 0.4, 0.5; y = 0, 0.25) synthesized using high-purity metals have been studied using X-ray diffraction analysis, heat capacity and magnetocaloric measurements. Dy0.5Ho0.5Co2 has a first order phase transition at the Curie temperature TC ≈ 110 K. Both Tb and Al substitution leads to increase of the TC. The increasing Tb content leads to the decreases slightly the MCE and all the transitions near the Curie temperature are of the first order. As for the Al-containing compounds, MCE measurements show that the phase transition type changes from the first to the second-order. The advantage of Tbx(Dy0.5Ho0.5)1-xCo1.75Al0.25 as compared with Al-free alloys is 'table-like' behavior of MCE.

  4. Structural elucidation and magnetic behavior evaluation of rare earth (La, Nd, Gd, Tb, Dy) doped BaCoNi-X hexagonal nano-sized ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Majeed, Abdul, E-mail: abdulmajeed2276@gmail.com [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Khan, Muhammad Azhar, E-mail: azhar.khan@iub.edu.pk [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Raheem, Faseeh ur; Hussain, Altaf; Iqbal, F. [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Murtaza, Ghulam [Centre for Advanced Studies in Physics, Government College University, Lahore 54000 (Pakistan); Akhtar, Majid Niaz [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Shakir, Imran [Deanship of Scientific Research, College of Engineering, King Saud University, PO Box 800, Riyadh 11421 (Saudi Arabia); Warsi, Muhammad Farooq [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan)

    2016-06-15

    Rare-earth (RE=La{sup 3+}, Nd{sup 3+}, Gd{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) doped Ba{sub 2}NiCoRE{sub x}Fe{sub 28−x}O{sub 46} (x=0.25) hexagonal ferrites were synthesized for the first time via micro-emulsion route, which is a fast chemistry route for obtaining nano-sized ferrite powders. These nanomaterials were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), as well as vibrating sample magnetometer (VSM). The XRD analysis exhibited that all the samples crystallized into single X-type hexagonal phase. The crystalline size calculated by Scherrer's formula was found in the range 7–19 nm. The variations in lattice parameters elucidated the incorporation of rare-earth cations in these nanomaterials. FTIR absorption spectra of these X-type ferrites were investigated in the wave number range 500–2400 cm{sup −1.} Each spectrum exhibited absorption bands in the low wave number range, thereby confirming the X-type hexagonal structure. The enhancement in the coercivity was observed with the doping of rare-earth cations. The saturation magnetization was lowered owing to the redistribution of rare-earth cations on the octahedral site (3b{sub VI}). The higher values of coercivity (664–926 Oe) of these nanomaterials suggest their use in longitudinal recording media. - Graphical abstract: Nano-sized rare-earth (RE=La{sup 3+}, Nd{sup 3+}, Gd{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) doped Ba{sub 2}NiCoRE{sub x}Fe{sub 28−x}O{sub 46} (x=0.25) hexagonal ferrites were synthesized for the first time via micro-emulsion route and the crystallite size was found in the range 7–19 nm. The enhancement in the coercivity was observed with the doping of rare-earth cations. The higher values of coercivity (664–926 Oe) of these nanomaterials suggest their use in longitudinal recording media. - Highlights: • Micro-emulsion route was used to synthesize Ba{sub 2}NiCoRE{sub x}Fe{sub 28−x}O{sub 46} ferrites. • The crystallite size was found

  5. Fabrication, magnetostriction properties and applications of Tb-Dy-Fe alloys: a review

    Directory of Open Access Journals (Sweden)

    Nai-juan Wang

    2016-03-01

    Full Text Available As an excellent giant-magnetostrictive material, Tb-Dy-Fe alloys (based on Tb0.27-0.30Dy0.73-0.70Fe1.9-2 Laves compound can be applied in many engineering fields, such as sonar transducer systems, sensors, and micro-actuators. However, the cost of the rare earth elements Tb and Dy is too high to be widely applied for the materials. Nowadays, there are two different ways to substitute for these alloying elements. One is to partially replace Tb or Dy by cheaper rare earth elements, such as Pr, Nd, Sm and Ho; and the other is to use non-rare earth elements, such as Co, Al, Mn, Si, Ce, B, Be and C, to substitute Fe to form single MgCu2-type Laves phase and a certain amount of Re-rich phase, which can reduce the brittleness and improve the corrosion resistance of the alloy. This paper systemically introduces the development, the fabrication methods and the corresponding preferred growth directions of Tb-Dy-Fe alloys. In addition, the effects of alloying elements and heat treatment on magnetostrictive and mechanical properties of Tb-Dy-Fe alloys are also reviewed, respectively. Finally, some possible applications of Tb-Dy-Fe alloys are presented.

  6. Prospect of TbDyFe Magnetostrictive Material

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    1. Global Market: Increasing Demand for TbDyFe Mater There is steady demand for TbDyFe materials international market, especially in USA, Europe and Jap Following table shows global status of such materials si their emergence in 1984. Development course of American Etrema Company reflects the prospect of such materials. At present, besi domestic market, Etrema Company has sales subsidiarie

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

    NARCIS (Netherlands)

    Fang, CM; Wiegers, GA; Haas, C

    1997-01-01

    Photoemission spectra (XPS and UPS) are presented for the valence band of misfit layer compounds (LnS)(1+x)TS2 with Ln = Dy, Ho or Tb; T = Nb or Ta. The Nb 4d(x)2 (or Ta 5d(x)2) conduction band is almost filled, which indicates a charge transfer of slightly less than one electron per T from the LnS

  8. High-pressure syntheses and characterization of the rare-earth fluoride borates RE{sub 2}(BO{sub 3})F{sub 3} (RE = Tb, Dy, Ho)

    Energy Technology Data Exchange (ETDEWEB)

    Hinteregger, Ernst; Pitscheider, Almut; Wurst, Klaus; Heymann, Gunter; Huppertz, Hubert [Innsbruck Univ. (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie; Enders, Michael [Innsbruck Univ. (Austria). Inst. fuer Pharmazie

    2013-11-15

    The new rare-earth fluoride borates RE{sub 2}(BO{sub 3})F{sub 3} (RE = Tb, Dy, Ho) were synthesized under high-pressure/high-temperature conditions of 1.5 GPa/1200 C for Tb{sub 2}(BO{sub 3})F{sub 3} and 3.0 GPa/900 C for Dy{sub 2}(BO{sub 3})F{sub 3} and Ho{sub 2}(BO{sub 3})F{sub 3} in a Walker-type multianvil apparatus from the corresponding rare-earth sesquioxides, rare-earth fluorides, and boron oxide. The single-crystal structure determinations revealed that the new compounds are isotypic to the known rare-earth fluoride borate Gd{sub 2}(BO{sub 3})F{sub 3}. The new rare-earth fluoride borates crystallize in the monoclinic space group P2{sub 1}/c (Z = 8) with the lattice parameters a = 16.296(3), b = 6.197(2), c = 8.338(2) A, {beta} = 93.58(3) for Tb{sub 2}(BO{sub 3})F{sub 3}, a = 16.225(3), b = 6.160(2), c = 8.307(2) A, {beta} = 93.64(3) for Dy{sub 2}(BO{sub 3})F{sub 3}, and a = 16.189(3), b = 6.124(2), c = 8.282(2) A, {beta} = 93.69(3) for Ho{sub 2}(BO{sub 3})F{sub 3}. The four crystallographically different rare-earth cations (CN = 9) are surrounded by oxygen and fluoride anions. All boron atoms form isolated trigonal-planar [BO{sub 3}]{sup 3-} groups. The six crystallographically different fluoride anions are in a nearly planar coordination by three rare-earth cations. (orig.)

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

    Science.gov (United States)

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

    2016-08-01

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

  10. CeNi3-type rare earth compounds: crystal structure of R3Co7Al2 (R=Y, Gd-Tm) and magnetic properties of {Gd-Er}3Co7Al2, {Tb, Dy}3Ni8Si and Dy3Co7.68Si1.32

    Science.gov (United States)

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

    2017-03-01

    The crystal structure of new CeNi3-type {Y, Gd-Tm}3Co7Al2 (P63/mmc. N 194, hP24) compounds has been established using powder X-ray diffraction studies. The magnetism of Tb3Ni8Si and Dy3Ni8Si is dominated by rare earth sublattice and the magnetic properties of R3Co7Al2 (R =Gd-Er) and Dy3Co7.68Si1.32 are determined by both rare earth and cobalt sublattices. Magnetization data indicate ferromagnetic ordering of {Tb, Dy}3Ni8Si at 32 K and 21 K, respectively. Gd3Co7Al2 and Tb3Co7Al2 exhibit ferromagnetic ordering at 309 K and 209 K, respectively, whereas Dy3Co7Al2, Ho3Co7Al2, Er3Co7Al2 and Dy3Co7.68Si1.32 show a field dependent ferromagnetic-like ordering at 166 K, 124 K, 84 K and 226 K, respectively followed by a low temperature transition at 34 K for Dy3Co7Al2, 18 K for Ho3Co7Al2, 56 K for Er3Co7Al2, 155 K and 42 K for Dy3Co7.68Si1.32. Among these compounds, Dy3Ni8Si shows largest magnetocaloric effect (isothermal magnetic entropy change) of -11.6 J/kg·K at 18 K in field change of 50 kOe, whereas Tb3Co7Al2, Dy3Co7Al2 and Dy3Co7.68Si1.32 exhibit best permanent magnet properties in the temperature range of 2-5 K with remanent magnetization of 11.95 μB/fu, 12.86 μB/fu and 14.4 μB/fu, respectively and coercive field of 3.0 kOe, 1.9 kOe and 4.4 kOe, respectively.

  11. Effect of rare earth additions on magnetic properties of Fe{sub 82}Nb{sub 2}B{sub 14}RE{sub 2} (RE = Y, Gd, Tb and Dy) amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chrobak, A., E-mail: artur.chrobak@us.edu.pl [Institute of Physics, Silesian University, 4 Uniwersytecka, 40-007 Katowice (Poland); Nosenko, V. [G.V. Kurdyumov Institute for Physics of Metals, NAS of Ukraine, Vernadsky ave. 36, 03142 Kyiv (Ukraine); Haneczok, G. [University of Silesia, Institute of Materials Science, 12 Bankowa, 40-007 Katowice (Poland); Boichyshyn, L.; Kotur, B. [Ivan Franko National University of Lviv, Kyryla and Mefodia St. 6, 79005 Lviv (Ukraine); Bajorek, A. [Institute of Physics, Silesian University, 4 Uniwersytecka, 40-007 Katowice (Poland); Zivotsky, O.; Hendrych, A. [Technical University of Ostrava, Institute of Physics, 17. listopadu 15, 708 33 Ostrava-Poruba (Czech Republic)

    2011-10-17

    Highlights: {yields} We studied magnetic properties of Fe{sub 82}Nb{sub 2}B{sub 14}RE{sub 2} (RE=Y,Gd,Tb,Dy) amorphous alloys. {yields} In a comparison with Fe{sub 82}Nb{sub 2}B{sub 14}Y{sub 2} alloy the rare earth editions cause an increase of the Curie temperature and a decrease of magnetic moment per magnetic atom. {yields} Doping of Tb and Dy lead to a strong decrease of magnetic permeability and a formation of low dimensional finger-print magnetic domains. - Abstract: In the present paper the influence of RE alloying additions (Y, Gd, Tb and Dy) on magnetic properties (Curie temperatures, low temperature magnetization, zero field cooling-field cooling curves, domain structure, room temperature magnetostriction and magnetic permeability) of amorphous alloys of type Fe{sub 82}Nb{sub 2}B{sub 14}RE{sub 2} are carefully examined. It was shown that substituting of yttrium atoms by magnetic elements, i.e. Gd, Tb and Dy leads to (i) an increase of the Curie temperature of amorphous phase from 416 K (for Fe{sub 82}Nb{sub 2}B{sub 14}Y{sub 2}) to 450 K (for Fe{sub 82}Nb{sub 2}B{sub 14}Gd{sub 2}) and (ii) a decrease of magnetization in saturation (magnetic field 7 T) which can be explained by antiferromagnetic Fe-RE coupling resulting in a decrease of magnetic moment calculated per magnetic atom from 2.00 {mu}{sub B} for the Fe{sub 82}Nb{sub 2}B{sub 14}Y{sub 2} alloy (Fe in amorphous phase) to 1.51 {mu}{sub B} for the Fe{sub 82}Nb{sub 2}B{sub 14}Tb{sub 2} alloy. It was concluded that Tb and Dy alloying additions introduce a local magnetic anisotropy responsible for significant decrease of initial magnetic permeability (about 5 times in relation to Fe{sub 82}Nb{sub 2}B{sub 14}Y{sub 2} or Fe{sub 82}Nb{sub 2}B{sub 14}Gd{sub 2} alloy), increase of magnetic irreversibility effect measured at 2 K (about 10 times in relation to the same alloys) and appearing of the finger-print magnetic domain regions (not observed for the Fe{sub 82}Nb{sub 2}B{sub 14}Y{sub 2} and Fe{sub 82}Nb

  12. Preparation and Performance of Magneto-optical Glasses Doped with Tb3+/Dy3+

    Institute of Scientific and Technical Information of China (English)

    YIN Hairong; ZHAO Gaoyang; LIU Pan; WANG Shunni; GUO Hongwei

    2014-01-01

    In order to increase the content of rare-earth oxides in magneto-optical glass and improve the Verdet constant, the rare-earth doped ternary Ga2O3-B2O3-SiO2(GBS) system magneto-optical glasses were prepared by the melt quenching technique. The influence of Tb3+and Dy3+ions on the structure of GBS glasses was investigated using FTIR, DSC and Faraday rotations. The experimental results showed that the content of rare-earth oxides in the glasses with the double incorporation of Tb2O3 and Dy2O3 was higher. The crystallization parameterβachieved the maximum 0.48 with Tb3+/Dy3+content of 35mol%. Terbium oxide existed mainly in [TbO3] units in the glasses and [TbO4] units were converted into [TbO3] with increasing Tb2O3 content. As Ga3+ion is larger than B3+ion in radius, leading to an increasing of the glass network gap and improvement in the ability of accommodating rare earth ions, Verdet constant increased.

  13. VUV spectroscopic properties of rare-earth (RE=Eu, Tb and Dy)-doped A2Zr(PO4)2 (A=Li, Na and K) phosphates

    Institute of Scientific and Technical Information of China (English)

    林啸; 冯昂; 张志军; 赵景泰

    2014-01-01

    This study fully investigated the vacuum ultraviolet excitation spectra of pure and rare-earth (RE=Eu, Tb and Dy)-doped A2Zr(PO4)2 (A=Li, Na and K) phosphors. The synthesized Na and Li compounds were characterized by XRD showing two new types of phases after indexation. Although these three pure compounds had different crystal structures, they exhibited similar luminescence properties. For Eu3+-activated samples, the broad excitation band centered at 217 nm could be attributed to the CT transition between O2- (2p6) and Eu3+ ions. For Tb3+-doped samples, two groups of f-d transitions were observed, where a strong broad band at 221 nm was due to the spin-allowed f-d transition. Energy transfer from O2-to Dy3+was not observed in Dy3+-doped phosphors, probably because it overlapped considerably with the CT transition from O2- to Zr4+at 187 nm.

  14. Large magnetocaloric effect and near-zero thermal hysteresis in the rare earth intermetallic Tb1-x Dy x Co2 compounds

    Science.gov (United States)

    Zeng, Yuyang; Tian, Fanghua; Chang, Tieyan; Chen, Kaiyun; Yang, Sen; Cao, Kaiyan; Zhou, Chao; Song, Xiaoping

    2017-02-01

    We report the magnetocaloric effect in a Tb1-x Dy x Co2 compound which exhibits a wide working temperature window around the Curie temperature (T C) and delivers a large refrigerant capacity (RC) with near-zero thermal hysteresis. Specifically, the wide full width at half maxima ({δ\\text{WFHM}} ) can reach up to 62 K and the RC value changes from 216.5 to 274.3 J Kg-1 when the external magnetic field increases to 5 T. Such magnetocaloric effects are attributed to a magnetic and structural transition from a paramagnetic and cubic phase to a ferromagnetic (M S along [1 1 1] direction) and rhombohedral phase or ferromagnetic (M S along [0 0 1] direction) and tetragonal phase.

  15. Spectroscopy and energy transfer in lead borate glasses doubly doped with Dy3+-Tb3+ and Tb3+-Eu3+ ions

    Science.gov (United States)

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

    2014-08-01

    Lead borate glasses doubly doped with Dy3+-Tb3+ and Tb3+-Eu3+ were investigated using optical spectroscopy. Luminescence spectra of rare earths were detected under various excitation wavelengths. The main green emission band due to 5D4 → 7F5 transition of Tb3+ is observed under excitation of Dy3+, whereas the main red emission band related to 5D0 → 7F2 transition of Eu3+ is successfully observed under direct excitation of Tb3+. In both cases, the energy transfer processes from Dy3+ to Tb3+ and from Tb3+ to Eu3+ 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.

  16. Characterization, electrical transport and magnetic properties of the rare earth misfit layer compounds (TbS)(1.21)NbS2, (TbS)(1.20)TaS2, (DyS)(1.22)NbS2 and (DyS)(1.21)TaS2

    NARCIS (Netherlands)

    Zhou, W.Y.; Meetsma, A.; deBoer, J.L.; Wiegers, G.A

    1996-01-01

    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 degrees around the c axis

  17. Magnetoelastic vibration damping properties of TbDy alloys

    Science.gov (United States)

    Dooley, Jennifer A.; Good, Nathan R.; White, Christopher V.; Leland, Robert S.

    2003-03-01

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

  18. Preparation of DyFe2 and TbFe2 by Reduction-Diffusion Process

    Institute of Scientific and Technical Information of China (English)

    Guangsi GUO; Guangtai WANG; Zhitong SUI

    2004-01-01

    The pure intermetallic compounds (Tb1-xDyx)Fe2 are super-magnetostriction materials, which were produced from DyFe2and TbFe2 in this paper. The thermodynamic possibility and kinetic feasible conditions for DyFe2 and TbFe2 preparation by reduction-diffusion in Ca-Dy2O3-Fe and Ca-Tb4O7-Fe systems were analyzed and the products of DyFe2 and TbFe2 were confirmed by XRD. The contracting core model was applied to describe the reduction-diffusion process in which the diffusion is a rate-controlled step. The apparent activation energies of DyFe2 and TbFe2 processes are 45 and 39 k J/mol respectively.

  19. Dynamic parameters of Tb-Dy-Fe giant magnetostrictive alloy

    Institute of Scientific and Technical Information of China (English)

    白夏冰; 蒋成保

    2010-01-01

    Tb0.3Dy0.7Fe1.90 oriented rods were prepared by zone melting with unidirectional solidification.The magnetomechanical coupling factor(k33) was measured by magnetomechanical resonance under different DC bias fields up to 77.4 mT.An effective method was provided to calculate sonic velocity,elastic modulus and compliance constant through measuring resonate frequency(fr),and calculate dynamic magnetostriction(d33) via measuring magnetic permeability,magnetomechanical coupling factor(k33) and compliance co...

  20. Effect of Ho-doping on microstructure and magnetostriction of TbDyFe alloys

    Institute of Scientific and Technical Information of China (English)

    JIANG Minhong; GU Zhengfei; CHENG Gang; LIU Xinyu

    2009-01-01

    Tb0.3Dy0.7HoxFe1.95 (x=0.00, 0.05, 0.10, 0.15, 0.20, 0.35, 0.50, 0.65) quaternary alloys were prepared by arc-melting and followed by annealing. The phases present and structure of the alloys were determined using a D8-Advance X-ray diffractometer. The magnetostriction of the alloys was studied by standard strain gauge technique. The dependence of Ho content on the structure, magnetostriction and density of the alloys was investigated in detail. The research results showed that Ho-doping did not change MgCu2-type cubic Laves structure in Tb0.3Dy0.7Fe1.95. When Ho content x≤0.2, rich rare earth phase presented in the alloys increased and magnetostriction of the alloys reduced evidently with increasing x, but for alloys with x>0.2, the content of rich rare earth phase started to reduce and the magnetostriction increased quickly, especially at low magnetic field in the alloy with x=0.65 due to separation of rich rare earth phases on the surface of the alloy.

  1. Complex magnetism of Ho-Dy-Y-Gd-Tb hexagonal high-entropy alloy

    Science.gov (United States)

    Lužnik, J.; Koželj, P.; Vrtnik, S.; Jelen, A.; Jagličić, Z.; Meden, A.; Feuerbacher, M.; Dolinšek, J.

    2015-12-01

    Rare earth based equimolar Ho-Dy-Y-Gd-Tb hexagonal high-entropy alloy (HEA) is a prototype of an ideal HEA, stabilized by the entropy of mixing at any temperature with random mixing of elements on the hexagonal close-packed lattice. In order to determine intrinsic properties of an ideal HEA characterized by the enormous chemical (substitutional) disorder on a weakly distorted simple lattice, we have performed measurements of its magnetic and electrical response and the specific heat. The results show that the Ho-Dy-Y-Gd-Tb hexagonal HEA exhibits a rich and complex magnetic field-temperature (H ,T ) phase diagram, as a result of competition among the periodic potential arising from the electronic band structure that favors periodic magnetic ordering, the disorder-induced local random potential that favors spin glass-type spin freezing in random directions, the Zeeman interaction with the external field that favors spin alignment along the field direction, and the thermal agitation that opposes any spin ordering. Three characteristic temperature regions were identified in the (H ,T ) phase diagram between room temperature and 2 K. Within the upper temperature region I (roughly between 300 and 75 K), thermal fluctuations average out the effect of local random pinning potential and the spin system behaves as a pure system of compositionally averaged spins, undergoing a thermodynamic phase transition to a long-range ordered helical antiferromagnetic state at the Néel temperature TN=180 K that is a compositional average of the Néel temperatures of pure Tb, Dy, and Ho metals. Region II (between 75 and 20 K) is an intermediate region where the long-range periodic spin order "melts" and the random ordering of spins in the local random potential starts to prevail. Within the low-temperature region III (below 20 K), the spins gradually freeze in a spin glass configuration. The spin glass phase appears to be specific to the rare earths containing hexagonal HEAs, sharing

  2. Magnetism in RRhGe (R = Tb, Dy, Er, Tm): An experimental and theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Sachin [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Suresh, K.G., E-mail: suresh@phy.iitb.ac.in [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Nigam, A.K. [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Lukoyanov, A.V. [Institute of Metal Physics, Russian Academy of Sciences, Ural Branch, Yekaterinburg 620137 (Russian Federation); Ural Federal University, Yekaterinburg 620002 (Russian Federation)

    2015-08-15

    Highlights: • RRhGe (R = Tb, Dy, Er, Tm) compounds show low temperature antiferromagnetic ordering. • All compounds show field induced metamagnetic transitions. • Some of these compounds show large magnetocaloric effect and magnetoresistance. • Change of sign in MR take place on temperature variation. - Abstract: RRhGe (R = Tb, Dy, Er, Tm) compounds have been studied by different experimental probes and theoretical ab initio calculations. These compounds show very interesting magnetic and transport properties. All the compounds are antiferromagnetic with some of them showing spin-reorientation transition at low temperatures. The magnetocaloric effect estimated from magnetization data shows high values in all these compounds. Magnetoresistance is negative near the ordering temperatures and positive at low temperatures. The electronic structure calculations accounting for electronic correlations in the 4f rare-earth shell reveal the closeness of the antiferromagnetic ground state and other types of magnetic orderings in the rare-earth sublattice. These calculations are also in agreement with the experimental results.

  3. Magnetic properties of R/sub 3/Rh/sub 2/ compounds with R = Gd, Tb, Dy, Ho and Er

    Energy Technology Data Exchange (ETDEWEB)

    Gignoux, D. (Centre National de la Recherche Scientifique, 38 - Grenoble (France). Lab. Louis Neel); Gomez-Sal, J.C.; Aramburu-Zabala, J.A. (Santander Univ. (Spain). Facultad de Ciencias); Paccard, D. (Universite de Savoie, 74 - Annecy-le-Vieux (France). Lab. Structure de la Matiere)

    1984-04-01

    Bulk magnetic measurements performed on polycrystalline samples of the tetragonal compounds R/sub 3/Rh/sub 2/ with R = Gd, Tb, Dy, Ho and Er are presented. All the compounds are ferromagnetic at low temperature. However in Tb/sub 3/Rh/sub 2/ an antiferromagnetic behaviour is observed between 14 and 24 K. In Gd/sub 3/Rh/sub 2/, where the magnetocrystalline anisotropy must be negligible, it seems that the magnetic structure is not collinear. In the other compounds the observed properties essentially result from indirect exchange interactions and crystal field effects acting on the rare earth ions which lie in low symmetry sites.

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

    NARCIS (Netherlands)

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

    2005-01-01

    We have studied the crystal and magnetic structures of the magnetoelectric materials RMn2O5 (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

  5. Green to white tunable light emitting phosphors: Dy3+/Tb3+ in zinc phosphate glasses

    Science.gov (United States)

    Juárez-Batalla, J.; Meza-Rocha, A. N.; Muñoz H., G.; Caldiño, Ulises

    2017-02-01

    Dy3+/Tb3+-doped zinc phosphate glasses of composition in mol.%: 98.0Zn(PO3)2-2.0Dy2O3, (100.0-x)Zn(PO3)2-xTb2O3 and (98.0-x)Zn(PO3)2-2.0Dy2O3-xTb2O3, x = 0.6, 1.0, 2.0 and 5.0, were prepared by conventional melt quenching technique, and characterized by photoluminescence and decay time spectroscopy. The emission color can be adjusted from neutral white of 4279 K (98.0 Zn(PO3)2-2.0 Dy2O3 glass) toward the green region by codoping with Tb3+ from 0.6 to 5.0 mol% of Tb2O3 upon Dy3+ excitation at 392 nm. The Tb3+ emissions (5D4 → 7F6,5,4,3) being sensitized by Dy3+ through a non-radiative energy transfer. Dysprosium 4F9/2 level emissions can also be sensitized through excitation of Tb3+ at 284 nm with an efficiency up to of 80%. Additionally, upon 284 nm excitation dominant 5D4 → 7F5 green emission in detriment of the 5D3 → 7FJ blue one is promoted by a cross relaxation process between Tb3+ and Dy3+ in addition to that among Tb3+ ions. In consequence, the most intense green emission observed in the ZP2Dy5Tb phosphor gives rise to a color purity of 67.8% and chromaticity coordinates (0.29, 0.59) very close to those (0.29, 0.60) of European Broadcasting Union illuminant green. Such cross relaxation processes enhancing the green emission of Tb3+ with ultraviolet excitation might contribute to increment the spectral response of solar photovoltaic cells by down-shifting of the incident solar spectrum.

  6. Magnetic order of Tb{sub 3}Co{sub 2.2}Si{sub 1.8} and Dy{sub 3}Co{sub 2.2}Si{sub 1.8} as a representative of the family of compounds with orthorhombic distortion of rare earth lattice

    Energy Technology Data Exchange (ETDEWEB)

    Morozkin, A.V., E-mail: morozkin@tech.chem.msu.ru [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Isnard, O. [CNRS, Institut Néel, 25 rue des Martyrs BP166 x, F-38042 Grenoble (France); Université Grenoble Alpes, Institut Néel, F-38042 Grenoble (France); Nirmala, R. [Indian Institute of Technology Madras, Chennai 600036 (India); Malik, S.K. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59082-970 (Brazil)

    2015-09-01

    Magnetic measurements indicate that the rare earth intermetallic compounds Tb{sub 3}Co{sub 2.2}Si{sub 1.8} and Dy{sub 3}Co{sub 2.2}Si{sub 1.8} (Dy{sub 3}Co{sub 2.2}Si{sub 1.8}-type) exhibit ferromagnetic transition at 132 K and 74 K and a spin-reorientation transition around 42 K and 35 K, respectively. Below Curie temperature, both compounds are soft ferromagnets, whereas below the spin reorientation transition they are permanent magnets with antiferromagnetic component: the values of critical field H{sub c}=30 kOe, coercive field H{sub coer}=17 kOe and residual magnetization M{sub res}=4.1 μ{sub B}/Tb for Tb{sub 3}Co{sub 2.2}Si{sub 1.8} and H{sub c}=14 kOe, H{sub coer}=21.5 kOe and M{sub res}=3.7 μ{sub B}/Dy for Dy{sub 3}Co{sub 2.2}Si{sub 1.8} at 2 K. The magnetocaloric effect of Dy{sub 3}Co{sub 2.2}Si{sub 1.8} is calculated in terms of isothermal magnetic entropy change (ΔS{sub m}) and it reaches a values of −16.5 J/kg K at 75 K for a field change of 140 kOe (−8.1 J/kg K at 70 K, for 0–50 kOe change) and −6.0 J/kg K for a field change of 140 kOe (−1.4 J/kg K, for 0–50 kOe change) around 40 K. Neutron diffraction study in zero applied field shows mixed ferro-antiferromagnetic ordering of Tb{sub 3}Co{sub 2.2}Si{sub 1.8} below ~127 K with wave vectors K{sub 0}=[0, 0, 0] and K{sub 1}=[±K{sub x}, 0, 0] (K{sub x}≈3/10). Between ~127 K and 53 K the magnetic structure of Tb{sub 3}Co{sub 2.2}Si{sub 1.8} is set of canted ferromagnetic cones with a resulting b-axis ferromagnetic component, whereas below 43 K its magnetic structure is set of canted ferromagnetic cones with a resulting c-axis ferromagnetic component. Between 53 K and 43 K the high-temperature magnetic order of Tb{sub 3}Co{sub 2.2}Si{sub 1.8} transforms to the low-temperature order via an intermediate state. The level of orthorhombic distortion of the Tb-sublattice determines the magnetic ordering of Tb{sub 3}Co{sub 2.2}Si{sub 1.8} in the Tb→Tb{sub 3}Co{sub 2.2}Si{sub 1.8}→Tb{sub 3}Co

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

    Energy Technology Data Exchange (ETDEWEB)

    Tereshina, I. S., E-mail: irina-tereshina@mail.ru [Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Baikov Institute of Metallurgy and Material Sciences, Russian Academy of Sciences, Moscow 119991 (Russian Federation); International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw 53-421 (Poland); Chzhan, V. B. [Baikov Institute of Metallurgy and Material Sciences, Russian Academy of Sciences, Moscow 119991 (Russian Federation); International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw 53-421 (Poland); National University of Science and Technology “MISIS”, Moscow 119049 (Russian Federation); Tereshina, E. A. [Institute of Physics CAS, Prague 18221 (Czech Republic); Khmelevskyi, S. [Center for Computational Materials Science, IAP, Vienna University of Technology, Vienna A-1040 (Austria); Burkhanov, G. S. [Baikov Institute of Metallurgy and Material Sciences, Russian Academy of Sciences, Moscow 119991 (Russian Federation); Ilyushin, A. S. [Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Complex Research Institute named after Kh. I. Ibragimov, Russian Academy of Sciences, Groznyi 364906 (Russian Federation); Paukov, M. A.; Havela, L. [Faculty of Mathematics and Physics, Charles University, Prague 12116 (Czech Republic); Karpenkov, A. Yu. [Physics Faculty, Tver State University, Tver 170100 (Russian Federation); Department of Physics, Chelyabinsk State University, Chelyabinsk 454001 (Russian Federation); Cwik, J.; Koshkid' ko, Yu. S.; Miller, M. [International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw 53-421 (Poland); Nenkov, K.; Schultz, L. [Leibniz-Institut fur Festkorper- und Werkstoffforschung, Dresden D-01171 (Germany)

    2016-07-07

    The influence of simultaneous substitution within the rare earth (R) and Co sublattices on the structural, magnetic, and magnetocaloric properties of the Laves phase RCo{sub 2}-type compounds is studied. Main attention is devoted to the studies of the magnetostructural phase transitions and the transition types with respect to the alloy composition. Multicomponent alloys Tb{sub x}(Dy{sub 0.5}Ho{sub 0.5}){sub 1−x}Co{sub 2} and Tb{sub x}(Dy{sub 0.5}Ho{sub 0.5}){sub 1−x}Co{sub 1.75}Al{sub 0.25} were prepared with the use of high purity metals. Majority of the Tb{sub x}(Dy{sub 0.5}Ho{sub 0.5}){sub 1−x}Co{sub 2} alloys exhibit magnetic transitions of the first-order type and a large magnetocaloric effect. The substitution of Al for Co in Tb{sub x}(Dy{sub 0.5}Ho{sub 0.5}){sub 1−x}Co{sub 2} increases the Curie temperature (T{sub C}) but changes the transition type from first-to the second-order. The discussion of the physical mechanisms behind the observed phenomena is given on the basis of the first principles electronic-structure calculations taking into account both the atomic disorder and the magnetic disorder effects at finite temperatures. The advantage of Al-containing materials is that sufficiently high magnetocaloric effect values are preserved at T > T{sub C}.

  8. The normal and inverse magnetocaloric effect in RCu2 (R=Tb, Dy, Ho, Er) compounds

    Science.gov (United States)

    Zheng, X. Q.; Xu, Z. Y.; Zhang, B.; Hu, F. X.; Shen, B. G.

    2017-01-01

    Orthorhombic polycrystalline RCu2 (R=Tb, Dy, Ho and Er) compounds were synthesized and the magnetic properties and magnetocaloric effect (MCE) were investigated in detail. All of the RCu2 compounds are antiferromagnetic (AFM) ordered. As temperature increases, RCu2 compounds undergo an AFM to AFM transition at Tt and an AFM to paramagnetic (PM) transition at TN. Besides of the normal MCE around TN, large inverse MCE around Tt was found in TbCu2 compound. Under a field change of 0-7 T, the maximal value of inverse MCE is even larger than the value of normal MCE around TN for TbCu2 compound. Considering of the normal and inverse MCE, TbCu2 shows the largest refrigerant capacity among the RCu2 (R=Tb, Dy, Ho and Er) compounds indicating its potential applications in low temperature multistage refrigeration.

  9. Tb-Dy-Fe Single Crystal and Magnetostrictive Actuator Using These Materials

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Magnetostrictive actuators normally use twin-crystal magnetostrictive materials as driving unit. Because the crystal and twin-crystal plane hinder the movement of the domain wall, its displacement output of low magnetic strength is rather small. Using Tb-Dy-Fe single crystal technique can effectively solve the problems brought by pollution and twin crystals, and produce high-quality Tb-Dy-Fe single crystal materials. The paper will introduce the technique of using these materials to produce magnetostrictive actuators that possess high sensitivity and resolution and use pulse feeding.

  10. Eu-, Tb-, and Dy-Doped Oxyfluoride Silicate Glasses for LED Applications

    DEFF Research Database (Denmark)

    Zhu, C.F.; Wang, J.; Zhang, M.M.

    2014-01-01

    Luminescence glass is a potential candidate for the light-emitting diodes (LEDs) applications. Here, we study the structural and optical properties of the Eu-, Tb-, and Dy-doped oxyfluoride silicate glasses for LEDs by means of X-ray diffraction, photoluminescence spectra, Commission Internationale...... de L’Eclairage (CIE) chromaticity coordinates, and correlated color temperatures (CCTs). The results show that the white light emission can be achieved in Eu/Tb/Dy codoped oxyfluoride silicate glasses under excitation by near-ultraviolet light due to the simultaneous generation of blue, green, yellow...

  11. Crystal fields of dilute Tb, Dy, or Er in Sc obtained by magnetization measurements

    DEFF Research Database (Denmark)

    Høg, J.; Touborg, P.

    1976-01-01

    Crystal-field parameters for dilute Sc-Tb, Sc-Dy, and Sc-Er alloys have been obtained by fitting theoretical expressions to the experimentally measured paramagnetic susceptibility. The initial susceptibility was measured and corrected for the effects of ordering at the lowest temperatures in the ...

  12. Synthesis, characterization and TL properties of SrSO4:Dy,Tb nanocrystalline phosphor

    Institute of Scientific and Technical Information of China (English)

    Khadijeh Rezaee Ebrahim Saraee; Amin Aghay Kharieky; Maryam Erfani

    2014-01-01

    SrSO4:Dy,Tb nanocrystalline with crystalline size in the range of 44-54 nm was prepared by co-precipitation method fol-lowed by thermal treatment and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and UV-visible spectrometry. Our results provided direct evidence of incorporation of impurities into nanocrystalline SrSO4. The thermoluminescence (TL) properties of SrSO4:Dy,Tb nanocrystalline pellets irradiated with gamma rays at different doses were studied. The TL glow curve of SrSO4:Dy,Tb nanocrystalline pellets had a prominent peak at around 490 K and a small peak at around 430 K. The major peak in the TL glow curve was almost resolved from other peaks, which was analyzed using Chen’s peak shape method to determine the TL kinetic parameters such as activation energy, E and kinetic order, b. The intensity of main dosimetric peak of SrSO4:Dy,Tb nanocrystalline pellets at around 490 K increased linearly with the increase in gamma dose. The TL response was linear in the range of 0.1-7 kGy. These properties made it a candidate as a dosimeter to be used for estimating the high dose of gamma rays.

  13. BaGdF5:Dy(3+),Tb(3+),Eu(3+) multifunctional nanospheres: paramagnetic, luminescence, energy transfer, and tunable color.

    Science.gov (United States)

    Guan, Hongxia; Song, Yanhua; Zheng, Keyan; Sheng, Ye; Zou, Haifeng

    2016-05-18

    A series of Dy(3+),Tb(3+) and Eu(3+) singly, doubly or triply doped BaGdF5 phosphors were synthesized by a one-step hydrothermal method with l-arginine, and their energy transfer, migrations and multicolored luminescence properties were investigated in detail. The as-prepared Dy(3+),Tb(3+) or Eu(3+) doped samples showed strong blue, green and red emission, respectively. Different hues of green and red light were obtained by co-doped Dy(3+),Tb(3+) and Tb(3+),Eu(3+) in the BaGdF5 host, respectively. More significantly, in the Dy(3+),Tb(3+),Eu(3+) tri-doped BaGdF5 phosphors, colors changed from yellow green to orange red by adjusting the doping concentration of Eu(3+). Energy migrations from Dy(3+) to Tb(3+) and from Tb(3+) to Eu(3+) are reported in detail. Furthermore, the obtained samples exhibit paramagnetic properties at room temperature and low temperature. It is obvious that these Dy(3+), Tb(3+), Eu(3+) singly or doubly or triply doped BaGdF5 nanomaterials with tunable multicolored luminescence properties may have potential applications in the fields of full-color displays, biological labels and bio-separation.

  14. 张应力对TbDy-Fe RGMF磁性能的影响%Effect of Tensile Stress on Magnetic Properties of TbDy-Fe Giant Magnetostrictive Thin Films

    Institute of Scientific and Technical Information of China (English)

    郑运相; 张鲁钟; 刘全洲; 周白杨

    2016-01-01

    The effect of the tensile stress on the magnetostriction and soft magnetic properties of the TbDy-Fe rare-earth giant magnetostrictive thin film (RGMF),synthesized by ion beam sputtering deposition (IBSD),was ex-perimentally investigated by measurement of cantilever deflection and hysteresis loop with LK-G150 laser micro-dis-placement sensor and alternating gradient magnetometer;mathematically modeled,theoretically analyzed and numer-ically simulated with software OOMMF.The simulated results show that the tensile stress significantly improves the magnetstrictive sensitivity of the TbDy-Fe RGMF at a low magnetic field,but slightly reduces the saturated magne-tostrictive sensitivity.To be specific,as the tensile stress increases,the coercive force of the TbDy-Fe RGMF decrea-ses,accompanied by an improvement of the magnetostrictive sensitivity at a low magnetic field.The simulated and measured results were found to be in fairly good agreement.%通过离子束溅射沉积法制备了受不同张应力作用的TbDy-Fe稀土超磁致伸缩薄膜样品.借助LK-G150激光微位移传感器和交变梯度磁强计分别测试薄膜的悬臂梁自由端偏转量与磁滞回线,通过微磁学模拟软件OOMMF模拟计算不同张应力作用下薄膜的磁性能;研究张应力对薄膜磁致伸缩性能及软磁性能的影响.结果表明:张应力能显著提高薄膜的低场磁敏性,但其饱和磁致伸缩性能有所降低;模拟计算结果与实验结果均表明:随着薄膜所受张应力的增加,薄膜的矫顽力逐渐减小,软磁性能得到了改善.

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

    CERN Document Server

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

    2015-01-01

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

  16. Mechanical and magnetostrictive properties of Tb0.36Dy0.64(Fe1-xMnx)1.9 alloys

    Institute of Scientific and Technical Information of China (English)

    MA Tian-yu; JIANG Cheng-bao

    2006-01-01

    The magnetization, magnetostriction and compressive strengths of arc-cast polycrystalline and directionally solidified Tb0.36Dy0.64(Fe1-xMnx)1.9 (x=0, 0.05, 0.10, 0.15, 0.20) rods were investigated by VSM, standard strain gauge method and compressive tests, respectively. The results show that the magnetostriction λs, saturation magnetization Ms and magnetocrystalline anisotropy constant K1 decrease with increasing the Mn concentration. The optical micrographs and XRD patterns show that the Tb0.36Dy0.64(Fe1-xMnx)1.9 alloys are composed of MgCu2-type Laves phase as matrix and a small amount of rare-earth rich phase. It is found that the distribution of the rare-earth rich phase has an important effect on mechanical property of Tb0.36Dy0.64(Fe1-xMnx)1.9 samples. For the arc-cast samples, smaller equal-axial grains are arranged irregularly, which results in higher compressive strengths. However, the rare-earth rich phase is arranged as parallel arrays in the directionally solidified samples, which leads to smaller compressive strengths.

  17. On the structures of the rare-earth metal germanides from the series REAl1-xGe3 (RE = Nd, Sm, Gd, Tb, Dy, Ho; 0.6 < x < 0.9). A tale of vacancies at the Al sites and the concomitant structural modulations.

    Science.gov (United States)

    Zhang, Jiliang; Liu, Yanyan; Shek, Chan Hung; Wang, Yingmin; Bobev, Svilen

    2017-07-18

    A series of ternary rare-earth metal aluminum germanides with the general formula REAl1-xGe3 (RE = Nd, Sm, Gd, Tb, Dy, and Ho; 0.6 < x < 0.9) have been synthesized by direct fusion of the corresponding elements. Their structures have been characterized by single-crystal X-ray diffraction and selected area electron diffraction methods. The average structure for all members is a representative of the orthorhombic SmNiGe3-type structure (Pearson symbol oS20, space group Cmmm), where the Al atoms occupy the Ni site, and the deep off-stoichiometry is due to statistical vacancies at this position. Considering long-range ordering of the vacancies, a monoclinic and a different orthorhombic structure, which represent idealized ordered variants, are possible, and the structural evolution depending on the nature of the rare-earth metals and the amount of vacancies at the aluminum site are discussed. Commensurate and incommensurate structural modulations based on these parent structures are also observed by electron diffraction, attesting to the great structural complexity in these systems. Magnetic susceptibility measurements are presented and discussed, along with the results from electronic band-structure calculations.

  18. Dy3+/Tb3+-codoped tunable warm light-emitting fluorogermanate glass phosphor

    Science.gov (United States)

    Alves, Rafaela T.; Trindade, Camyla M.; Santos, Weslley Q.; Gouveia-Neto, Artur S.; Bueno, Luciano A.; Mathias, Caio F.; Nalin, Marcelo

    2016-11-01

    Polychromatic tunable visible light emission in the region of the low correlated color temperature range using Dy3+/Tb3+ codoped PbGeO3:PbF2:CdF2 glass phosphor under UV-blue LED light excitation is presented. The glass phosphor was synthesized and the light emission feature was examined under UV-blue (353, 375, 385, and 405 nm) excitation. Emission around 484, 573, 663, and 754 nm due to dysprosium, and 488, 545, 585, 620, and 690 nm owing to terbium ions, was observed and analyzed as a function of the dysprosium and terbium contents and excitation wavelength. The excitation spectrum was examined and showed resonance peaks around 385 nm for the 573-nm emission of Dy3+, and 375 nm for the 545 nm of Tb3+. Energy-transfer process from Dy3+(F) to Tb3+(D) was also observed. Results indicated that the polychromatic visible light emitter herein reported produced light possessing tunable color tone via excitation wavelength and ions' mass ratio. The tint of the tunable overall emission resided in the warm region of the white-light boundary of the CIE-1931 chromaticity diagram.

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

    Science.gov (United States)

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

    1998-03-01

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

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

    Science.gov (United States)

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

    2008-09-01

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

  1. Effects of substrate temperature and annealing treatment on the microstructure and magnetic characteristics of TbDyFe films

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A series of TbDyFe films were prepared by DC magnetron sputtering. The effects of substrate temperature and annealing temperature on the phase structure and the magnetic properties of the sample films were investigated. The annealing treatment has a significant influence on the microstructure and the magnetic properties of the sample. The results obtained by XRD indicate that the films deposited at a temperature lower than 525℃ are amorphous and have an easy magnetization direction perpendicular to the film plane. An RFe2 phase is formed in the sample annealed at 550℃ and the residual phases observed are Fe and rare earth oxide. The magnetic properties Hc and Mr/Ms of the film annealed at 550℃ obtain the maximum values, for which the formation of the RFe2 phase is mainly responsible. An annealing treatment leads to a rotation of the sample's easy axis from being parallel to the film surface to becoming vertical.

  2. High field magnetization processes in single crystals of alpha-Tb{sub 2}S{sub 3} and alpha-Dy{sub 2}S{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Ebisu, S; Omote, H; Nagata, S [Department of Materials Science and Engineering, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran, Hokkaido 050-8585 (Japan); Koyama, K, E-mail: ebisu@mmm.muroran-it.ac.j [HFLSM, Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    2009-03-01

    Rare earth sesquisulfides alpha-Tb{sub 2}S{sub 3} and alpha-Dy{sub 2}S{sub 3} possess orthorhombic crystal structure having two independent rare earth sites. High field magnetization processes for single crystals of these compounds have been investigated up to mu{sub o}H = 18 T. Some step-like transitions have been observed in both compounds. The magnetization of alpha-Tb{sub 2}S{sub 3} single crystal under the field along the 6-axis at T = 1.4 K shows a steep increase of about 4.5 mu{sub B}, which corresponds to a half of full saturation moment of free Tb{sup 3+}, at mu{sub o}H = 2.2 T. It is considered that the reorientation of Tb{sup 3+} moments on only one Tb site into a ferromagnetic arrangement occurs. When the magnetic field is perpendicular to the b-axis, one-step transition at mu{sub o}H = 0.7 T for H||c and two-step transitions at 0.7 and 1.2 T for H||a are observed. As for alpha-Dy{sub 2}S{sub 3}, the magnetization curve at T = 1.5 K shows two-step transitions at 1.3 and 1.6 T (H||b), three or four dull steps (H||a or c). The total height of two steps in the M-H curve for H||b corresponds to a half of full Dy{sup 3+} moment.

  3. Substrate induced magnetostrictive anisotropy in heat treated ion-beam sputtered TbDyFe(+Zr) single and TbDyFe+Zr/Nb multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, S.F.; Faber, P.; Kronmueller, H. [Max-Planck-Institut fuer Metallforschung, Stuttgart (Germany)

    1998-07-01

    The effect of anisotropic thermal expansion of (1 anti 100)-oriented sapphire substrates has been investigated with respect to magnetostrictive anisotropy in sputter deposited (Tb{sub 0.27}Dy{sub 0.73}){sub 1-x}Fe{sub x} single layers and [(Tb{sub 0.27}Dy{sub 0.73}){sub 0.27}Fe{sub 0.73} + 2 at% Zr]/Nb multilayers. It is found that the thermally induced anisotropic film stress due to the anisotropic thermal expansion of sapphire can result in a magnetostrictive inplane transversal anisotropy. This may be of major interest for giant magnetostrictive thin film applications in microsystems where reversible magnetomechanical switching elements are required. Magnetic, magnetostrictive and microstructural (XRD) experiments have been performed. Magnetostriction has been measured at room temperature using the cantilever method with maximum inplane applied fields of 0.8 T. Ratios {lambda} {sub parallel} /{lambda} {sub perpendicular} {sub to} of magnetostrictions in fields applied parallel and transversal to the cantilever's longside ([0001]-substrate direction) are taken as a measure of the magnetostrictive inplane anisotropy. We found that {lambda} {sub parallel} /{lambda} {sub perpendicular} {sub to} (0.8 T) is varying with the microstructure (average grain sizes d) resulting from different heat treament. It is assumed that within the competition of magnetoelastic (favouring an inplane transversal anistropy) and magnetocrystalline interactions (favouring an inplane isotropy) the second will dominate for larger average grain sizes. This is indicated by comparison of nanocrystalline films on sapphire with different grain sizes d: amorphous or nanocrystalline (d < 25 nm) films exhibit a transversal magnetostrictive anisotropy ({lambda} {sub parallel} /{lambda} {sub perpendicular} {sub to} (0.8 T) >> 2) while stable crystalline films show magnetostrictive inplane isotropy ({lambda} {sub parallel} /{lambda} {sub perpendicular} {sub to} (0.8 T) {proportional_to} 1). (orig.)

  4. The magnetostriction of Tb, Dy and Ho revisited

    Energy Technology Data Exchange (ETDEWEB)

    Benito, L; Arnaudas, J I; Ciria, M; Fuente, C de la; Moral, A del [Departamento de Magnetismo de Solidos, Departamento de FIsica de la Materia Condensada-ICMA, Universidad de Zaragoza-CSIC, 50071 Zaragoza (Spain)

    2004-10-06

    In this paper we present re-analyses of magnetostriction measurements earlier performed in terbium, dysprosium and holmium single crystals. In the framework of the standard theory of single-ion crystal-electric-field and two-ion exchange magnetostrictions, we explain the thermal variation of the anisotropic saturation magnetostriction within the basal plane by considering high-order terms in the magnetoelastic energy. Using complementary basal-plane magnetic anisotropy measurements, we have been able to obtain the second- and fourth-order magnetoelastic coupling parameters associated with the orthorhombic distortion of the hexagonal plane for the above-mentioned three heavy rare earths.

  5. Hydrothermal Synthesis and Characterization of Pyrochlore Titanate R2 Ti2O7(R=Gd3+, Tb3+, Dy3+)

    Institute of Scientific and Technical Information of China (English)

    PENG Wen; HU Bin; CHEN Yan; HU Wei-wei; GUO Li; YUAN Hong-ming; FENG Shou-hua

    2011-01-01

    Pyrochlore titanate oxides, R2Ti2O7(R=Gd3+, Tb3+, Dy3+), were synthesized under mild hydrothermal conditions. The crystal growth of pyrochlore titanate oxides and taking place of chemical reaction in the hydrothermal processing were sensitive to the alkalinity, temperature, reaction time, the nature of the rare earth ion and the composition of initial reaction mixture. The as-prepared samples were characterized by powder X-ray diffraction, scanning electron microscopy, Raman spectrum and variable temperature dc magnetic susceptibility(Superconductivity quantum interference device, SQUIDS). The magnetic studies gave 7.29× 10-23 A·m2/Gd3+ and -8.28 K, 8.75 × 10-23 A·m2/ Tb3+ and -19.7 K, and 8.85×10-23 A·m2/Dy3+ and 0.84 K effective moments and Weiss constants for Gd2Ti2O7,Tb2Ti2O7 and Dy2Ti2O7, respectively.

  6. Fiber optic magnetic field sensor based on the TbDyFe rod

    Science.gov (United States)

    Chen, Feifei; Jiang, Yi

    2014-08-01

    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 μT - 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.

  7. Investigation on the Orientation Transition of Oriented Magnetostrictive TbDyFe Crystals

    Institute of Scientific and Technical Information of China (English)

    LIU Wei; JIANG Cheng-bao

    2006-01-01

    and TbDyFe magnetostrictive oriented crystals were prepared by the zone-melting unidirectional solidification method at 240 mm/h and 720 mm/h respectively. oriented crystals were also obtained with oriented seeds with the same technique as for growing the oriented crystals. It is confirmed that this technique is stable for growing the oriented crystals in the TbDyFe alloys. Meanwhile, the variation of orientation, the solidification morphology and the magnetostriction were studied during the transition from oriented seeds to the oriented crystal growth. As the growth speeds up, the preferred orientation changed from to , and its morphology develops from of initial cellular to dendritic gradually. When an axial compressive pre-stress of 10 MPa is applied, the magnetostriction at the bottom, the middle and the top are 972×10-6, 918×10-6 and 900×10-6 at 100 mT respectively. The middle sections with mixed orientations have the same high magnetostriction performance as those with a single preferred orientation, which may be due to its celluar-dendritic morphology.

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

    Science.gov (United States)

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

    2015-05-01

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

  9. 磁感应强度和冷却速率对Tb0.27Dy0.73Fe1.95合金凝固过程中取向行为的影响∗%Influence of magnetic flux density and co oling rate on orientation behavior of Tb0.27Dy0.73Fe1.95 alloy during solidification pro cess

    Institute of Scientific and Technical Information of China (English)

    高鹏飞; 刘铁; 柴少伟; 董蒙; 王强

    2016-01-01

    实验研究了磁感应强度和冷却速率对Tb0.27 Dy0.73 Fe1.95合金凝固过程中(Tb, Dy)Fe2相取向行为及合金磁性能的影响.结果表明,将强磁场作用于Tb0.27Dy0.73Fe1.95合金的凝固过程可以制备出(Tb, Dy)Fe2相沿⟨111⟩取向的组织,同时显著提高了合金的磁致伸缩性能;通过提高磁感应强度可以在更快的冷却速率下得到⟨111⟩取向的组织;在4—10 T范围内,随着冷却速率的增加,(Tb, Dy)Fe2相沿⟨111⟩取向所需的磁感应强度增加,而发生⟨110⟩取向的磁感应强度减小.随着冷却速率的增加,合金的饱和磁化强度增加,而强磁场的施加对合金饱和磁化强度的变化没有明显影响.(Tb, Dy)Fe2相的取向行为受(Tb, Dy)Fe3相取向行为的影响,且由磁晶各向异性能与磁场作用时间共同控制.%The rare-earth giant magnetostrictive material Tb0.27Dy0.73Fe1.95 is one of the most important functional magnetic materials. Their superior properties include high saturation magnetostrictive coefficient at room temperature, high electromechanical coupling coefficients, high output power, fast response, high energy density, and non-contact drive. Thus, they can be used to build sensors, precision machinery, magnetomechanical transducers, and adaptive vibration-control systems. In this material, the magnetic phase (Tb, Dy)Fe2 has a typical MgCu2-type cubic Laves phase structure and exhibits different magnetostrictive properties along different crystal orientations. The ⟨111⟩ direction of this phase is the easy magnetization axis, along which the linear magnetostriction is higher than other directions. Thus, researchers have focused on preparing (Tb, Dy)Fe2 with a crystallographic orientation along or close to the⟨111⟩direction. Generally, the directional solidification method is used to prepare the Tb0.27Dy0.73Fe1.95 alloy. However, a crystal orientated along the ⟨110⟩ or ⟨112⟩ direction is always obtained and both of

  10. Magnetic ordering of R{sub 3}Cu{sub 4}Sn{sub 4} (R = Tb, Dy, Ho and Er)

    Energy Technology Data Exchange (ETDEWEB)

    Wawrzynska, E [M Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Cracow (Poland); Hernandez-Velasco, J [BENSC, Hahn-Meitner Institut, Glienicker Strasse 100, D-14109 Berlin (Germany); Penc, B [M Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Cracow (Poland); Sikora, W [Faculty of Physics and Nuclear Techniques, University of Mining and Metallurgy, Reymonta 19, 30-059 Cracow (Poland); Szytula, A [M Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Cracow (Poland); Zygmunt, A [W Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Dorodna 2, 50-950 Wroclaw (Poland)

    2003-08-06

    Neutron diffraction studies of polycrystalline R{sub 3}Cu{sub 4}Sn{sub 4} (R = Tb, Dy, Ho, Er) intermetallic compounds with the orthorhombic Gd{sub 3}Cu{sub 4}Ge{sub 4}-type crystal structure indicate the existence of different magnetic structures. Rare earth atoms occupy two non-equivalent 2d and 4e sublattices. The rare earth magnetic moments order at low temperatures. For R = Tb and Dy the magnetic structures below the Neel temperature are described by the propagation vectors k = (0, 0, 1/2 + {delta}). In these compounds both rare earth sublattices order. For R = Ho the magnetic structure is more complicated. There are two vectors; one of them is k = (0, 1/2, 0) whereas the second one changes with temperature. For the Er compound there is the propagation vector k = (1/2, 1/2, 0) which describes the magnetic ordering in the 2d sublattice and at low temperatures is accompanied by the propagation vector k = (0, 0,{delta}) describing the ordering in the 4e sublattice.

  11. Determination of magnetic anisotropy in the LnTRENSAL complexes (Ln = Tb, Dy, Er) by torque magnetometry.

    Science.gov (United States)

    Perfetti, Mauro; Lucaccini, Eva; Sorace, Lorenzo; Costes, Jean Pierre; Sessoli, Roberta

    2015-04-06

    We report here a study about the magnetic anisotropy of the LnTRENSAL complexes (Ln = Tb, Dy, Er) performed by using cantilever torque magnetometry and electron paramagnetic resonance. For all of the compounds, we extracted a set of crystal-field parameters to obtain the energy-level splitting of the ground-state multiplet.

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

    Science.gov (United States)

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

    2016-06-01

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

  13. Magnetic structures of R{sub 3}Cu{sub 4}Ge{sub 4} (R=Tb, Dy, Ho, Er)

    Energy Technology Data Exchange (ETDEWEB)

    Wawrzynska, E. E-mail: wawrzyn@castor.if.uj.edu.pl; Hernandez-Velasco, J.; Penc, B.; Szytula, A.; Zygmunt, A

    2003-08-01

    Neutron diffraction studies of polycrystalline R{sub 3}Cu{sub 4}Ge{sub 4} (R=Tb, Dy, Ho, Er) intermetallic compounds with the orthorhombic Gd{sub 3}Cu{sub 4}Ge{sub 4}-type crystal structure indicate complex magnetic structures. In these compounds the rare earth atoms occupy two nonequivalent 2d and 4e sublattices. For R=Tb and Er with decreasing temperature the magnetic moments in the 2d sublattice order first; the 4e sublattice magnetic moments order at lower temperatures. For R=Dy, Ho both sublattices order simultaneously although the magnetic moment values are different for each of them. In the compounds with R=Tb and Er a change of the magnetic structure, connected with the 2d sublattice, is observed near the Neel temperature. This is a transition from the commensurate structure, described by the propagation vector k=(0,((1)/(2)),0) at low temperatures to the incommensurate structure with k=(0,((1)/(2))+{delta},0) at higher temperatures (still below the Neel temperature)

  14. Dy(3)(+) -, Sm(3)(+) -, Ce(3)(+) - and Tb(3)(+) -activated optical properties of microcrystalline BaMgP2 O7 phosphors.

    Science.gov (United States)

    Wani, J A; Dhoble, N S; Kokode, N S; Singh, Vijay; Dhoble, S J

    2017-03-01

    Photoluminescence (PL) and thermoluminescence (TL) properties of rare earth (RE) ion (RE = Dy(3)(+) , Sm(3)(+) , Ce(3)(+) , Tb(3)(+) ) activated microcrystalline BaMgP2 O7 phosphors are presented in this work. Non-doped and doped samples of BaMgP2 O7 were prepared using a solid state diffusion method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), PL and TL. The XRD measurement confirmed the phase purity of the BaMgP2 O7 host matrix. The average particle size was found through SEM measurement to be around 2 μm. All activators using the PL technique displayed characteristic excitation and emission spectra that corresponded to their typical f → f and f → d transitions respectively. Thermoluminescence measurements showed that BaMgP2 O7 :RE (RE = Dy(3)(+) , Sm(3)(+) , Tb(3)(+) , Ce(3)(+) ) and co-doped BaMgP2 O7 :Ce(3)(+) ,Tb(3)(+) phosphors have also TL behaviour.

  15. KCa4(BO33:Ln3+ (Ln = Dy, Eu, Tb phosphors for near UV excited white–light–emitting diodes

    Directory of Open Access Journals (Sweden)

    Allu Amarnath Reddy

    2013-02-01

    Full Text Available A series of doped KCa4(BO33:Ln3+ (Ln: Dy, Eu and Tb compositions were synthesized by solid–state reaction method and their photoluminescent properties were systematically investigated to ascertain their suitability for application in white light emitting diodes. The X–ray diffraction (XRD and nuclear magnetic resonance (MAS–NMR data indicates that Ln3+–ions are successfully occupied the non–centrosymmetric Ca2+ sites, in the orthorhombic crystalline phase of KCa4(BO33 having space group Ama2, without affecting the boron chemical environment. The present phosphor systems could be efficiently excitable at the broad UV wavelength region, from 250 to 350 nm, compatible to the most commonly available UV light–emitting diode (LED chips. Photoluminescence studies revealed optimal near white–light emission for KCa4(BO33 with 5 wt.% Dy3+ doping, while warm white–light (CIE; X = 0.353, Y = 0.369 is obtained at 1wt.% Dy3+ ion concentration. The principle of energy transfer between Eu3+ and Tb3+ also demonstrates the potential white–light from KCa4(BO33:Eu3+,Tb3+ phosphor. Whereas, single Tb3+ and Eu3+–doped systems showed bright green (Tb3+ and red (Eu3+ emissions, respectively. Having structural flexibility along with remarkable chemical/thermal stability and suitable quantum efficiency these phosphors can be promising candidates as white–light–emitter for near UV LEDs.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-07-10

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

  17. Luminescence in Ba2 Sr2 Al2 O7 :RE (RE = Tb(3) (+) ,Eu(3) (+) and Dy(3) (+) ) novel aluminate phosphors.

    Science.gov (United States)

    Pardhi, S A; Panse, V R; Dhoble, S J

    2016-09-01

    The luminescence of novel rare earth (Tb(3) (+) , Eu(3) (+) and Dy(3) (+) )-activated Ba2 Sr2 Al2 O7 phosphors for solid-state lighting is presented. The aluminate phosphors were synthesized using a one-step combustion method. X-Ray diffraction, scanning electron microscopy and photoluminescence characterizations were performed to understand the mechanism of excitation and the corresponding emission in the as-prepared phosphor, as characterized the phase purity and microstructure. Improvements in the luminescence properties of the phosphors with rare earth concentration were observed. The phosphor hue could be tuned from blue, green and red by proper selection of rare earth ions in typical concentrations. Effective absorption in the near-ultraviolet region was observed, which makes the phosphor a potential candidate for ultraviolet light-emitting diodes. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

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

    Science.gov (United States)

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

    2010-01-18

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

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

    Science.gov (United States)

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

    2015-01-05

    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.

  20. Photoluminescence properties of BaMoO4:RE3+ (RE = Eu, Sm, Dy, Tb, Tm) phosphors

    Science.gov (United States)

    Cho, Shinho

    2016-11-01

    Rare-earth (RE)-activated barium molybdate phosphors for multicolor display applications were synthesized with different activator ions via a solid-state reaction. The effects of the activator ions on the structural, morphological, and optical properties of barium molybdate phosphors were investigated. The XRD spectra of all the phosphors, regardless of the activator ion, exhibited that the main peak of the phosphors occurred at the (112) plane, indicating the tetragonal BaMoO4 structure. The crystalline particles exhibited a tendency to agglomerate with irregular shapes and sizes. The emission spectra of RE-ion-doped BaMoO4 phosphors under ultraviolet excitation consisted of multicolor emissions: blue for Tm3+ activator ions, green for Tb3+ activator ions, yellow for Dy3+ activator ions, reddish orange for Eu3+ activator ions, and red for Sm3+ activator ions. These results suggest that multicolor emission can be realized by incorporating appropriate activator ions into the BaMoO4 host lattice.

  1. Coherent phonons in pyrochlore titanates A2Ti2O7 (A= Dy, Gd, Tb): A phase transition in Dy2Ti2O7 at 110 K

    Science.gov (United States)

    Kamaraju, N.; Kumar, Sunil; Saha, Surajit; Singh, Surjeet; Suryanarayanan, R.; Revcolevschi, A.; Sood, A. K.

    2011-04-01

    We study the generation of coherent optical phonons in spin-frustrated pyrochlore single crystals Dy2Ti2O7, Gd2Ti2O7, and Tb2Ti2O7 using femtosecond laser pulses (65 fs, 1.57 eV) in degenerate time-resolved transmission experiments as a function of temperature from 4 to 296 K. At 4 K, two coherent phonons are observed at ~5.3 THz (5.0 THz) and ~9.3 THz (9.4 THz) for Dy2Ti2O7 (Gd2Ti2O7), whereas three coherent phonons are generated at ~5.0, 8.6, and 9.7 THz for Tb2Ti2O7. In the case of spin-ice Dy2Ti2O7, a clear discontinuity is observed in the linewidths of both the coherent phonons as well as in the phase of lower-energy coherent phonon mode, indicating a subtle structural change at 110 K. Another important observation is a phase difference of π between the modes in all the samples, thus suggesting that the driving forces behind the generation of these modes could be different in nature, unlike a purely impulsive or displacive mechanism.

  2. Subsolidus Phase Relations of the CaO-REOx-CuO Systems (RE = Eu, Tb, Dy, Ho, Er, Lu and Sc) at 900 °C in Air

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude

    2016-01-01

    The subsolidus phase relations of the CaO-REOx-CuO systems (RE = Eu, Tb, Dy, Ho, Er, Lu and Sc) were investigated in air at 900 °C. The pseudo-ternary sections with RE = Tb, Dy, Ho, Er and Lu have a similar structure. They have in common with the RE = Eu system a solid solution of Ca0.833−xRExCuO2...... in the other systems at 900 °C in air....

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

    Science.gov (United States)

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

    2016-09-01

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

  4. Magnetocaloric properties of TbN, DyN and HoN nanopowders prepared by the plasma arc discharge method.

    Science.gov (United States)

    Shinde, K P; Jang, S H; Kim, J W; Kim, D S; Ranot, M; Chung, K C

    2015-12-21

    We report for the first time the synthesis of nanopowders of TbN, DyN and HoN crystallized in a cubic structure by the plasma arc discharge (PAD) method and investigate their magnetocaloric properties for magnetic refrigeration applications. The nitridization of terbium, dysprosium and holmium was obtained using a mixture of nitrogen and argon gas inside a discharge chamber with 4 kPa pressure. The structural and microstructural properties of these rare earth nitrides were investigated by using X-ray diffraction and transmission electron microscopy. The studied nitrides undergo a second-order ferromagnetic to paramagnetic phase transition at Curie temperatures of 35.7, 19.9 and 14.2 K for TbN, DyN and HoN, respectively. The magnetocaloric effects were estimated by calculating the magnetic entropy changes from the magnetization data sets measured at the different applied magnetic fields and temperatures. The changes in entropy -ΔSM were found to be 12.0, 13.6 and 24.5 J kg(-1) K(-1) at an applied magnetic field of 5 T.

  5. Crystal structure of Tb5Ni2In4, and magnetic properties of Dy5Ni2In4

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-02-27

    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.

  6. Magnetic phase diagrams of R2RhIn8 (R = Tb, Dy, Ho, Er and Tm) compounds.

    Science.gov (United States)

    Cermák, P; Kratochvílová, M; Pajskr, K; Javorský, P

    2012-05-23

    We have grown and characterized single crystals of R(2)RhIn(8) (R=Tb, Dy, Ho, Er and Tm) compounds crystallizing in the tetragonal Ho(2)CoGa(8)-type crystal structure. Their magnetic properties were studied by specific heat and magnetization measurements. All the investigated compounds order antiferromagnetically with Néel temperatures of 43.6, 25.1, 10.9, 3.8 and 4.1 K, respectively. Magnetic phase diagrams were constructed.

  7. Optical absorption, luminescence, and energy transfer processes studies for Dy3+/Tb3+-codoped borate glasses for solid-state lighting applications

    Science.gov (United States)

    Lakshminarayana, G.; Kaky, Kawa M.; Baki, S. O.; Lira, A.; Caldiño, U.; Kityk, I. V.; Mahdi, M. A.

    2017-10-01

    By using melt quenching technique, good optical quality singly doped Dy3+ or Tb3+ and Dy3+/Tb3+-codoped borate glasses were synthesized and studied by optical absorption, excitation, emission and decay lifetimes curve analysis. Following the absorption spectrum, the evaluated Judd-Ofelt (J-O) intensity parameters (Ωλ (λ = 2, 4 and 6)) were used to calculate the transition probability (AR), the branching ratio (βR), and the radiative lifetime (τR) for different luminescent transitions such as 4I15/2 → 6H15/2, 4F9/2 → 6H15/2, 4F9/2 → 6H13/2, 4F9/2 → 6H11/2 and 4F9/2 → 6H9/2,6F11/2 for the 0.5 mol % singly Dy3+-doped glass. The βR calculated (65%) indicates that for lasing applications, 4F9/2 → 6H13/2 emission transition is highly suitable. For all the Dy3+/Tb3+-codoped glasses, Tb3+: 5D3→7F6 emission decay lifetime curves are found to be non-exponential in nature for different concentrations of Dy3+ codoping. Using the Inokuti-Hirayama model, these nonexponential decay curves were analyzed to identify the nature of the energy transfer (ET) processes and here the electric dipole-dipole interaction is dominant for the ET. Based on the excitation and emission spectra and decay lifetimes curve analysis, the cross relaxation and ET processes between Dy3+ and Tb3+ were confirmed. For the 0.5 mol % Tb3+ and 2.0 mol % Dy3+-codoped glass, the evaluated Tb3+→Dy3+ ET efficiency (η) is found to be 45% under 369 nm excitation. Further, for Tb3+/Dy3+ -codoped glasses, an enhancement of Tb3+ green emission is observed up to 1.5 mol % Dy3+ codoping, and this is due to the non-radiative resonant ET from Dy3+ to Tb3+ upon 395 nm excitation. For singly 0.5 mol % Dy3+ or 0.5 mol % Tb3+-doped glass, the calculated color coordinates (x,y) and correlated color temperatures (CCT) represent the neutral white or warm white light regions, whereas Dy3+/Tb3+-codoped glasses (x,y) and CCT values fall in the yellowish green region with respect to the different Dy3

  8. Preparation and Magnetostriction of Tb0.22Dy0.48HO0.35Fe2 Alloys

    Institute of Scientific and Technical Information of China (English)

    Jiang Minhong

    2007-01-01

    Tb0.22Dy0.48Ho0.35Fe2 quaternary alloys are prepared by melting-top casting-annealing process. X-ray diffraction reveals that the alloy is single phase polycrystalline alloy with MgCu2 type cubic Laves phase structure, and (511) preferred orientation occurs in its. The magnetostriction measurements are carried out at room temperature using standard strain gauge technique in magnetic fields up to 400kA·m-1. The results show that when the magnetic field, H, is 90kA·m-1, the magnetostriction, λ ,of Tb0.22Dy0.48Ho0.35Fe2 quaternary alloys is 260×10-6, and when the H is 210kA·m-1, the λ is 438×10-6. When the H is 400kA·m-1, the λ is up to the saturation value, 538×10-6. As compared with TbDyFe ternary alloys, the λ of the quaternary alloy is significantly higher when the H is less than or equal to 210kA·m-1. When the H is 120kA·m-1,the λ of the alloy is 333×10-6,70×10-6 more than the ternary alloy. Research results and mechanism are discussed.

  9. Surface Modification of (Tb, Dy) Fe2 Alloy by Nitrogen Ion Implantation%( Tb,Dy) Fe2合金表面离子注入渗氮改性及抗腐蚀性能研究

    Institute of Scientific and Technical Information of China (English)

    王海波; 张世荣; 于敦波; 李红卫; 李扩社

    2012-01-01

    采用离子注入技术在(Tb,Dy)Fe2稀土超磁致伸缩材料表面引入氮离子进行改性处理,研究了加速电压对材料表面相结构、微观形貌、表面硬度、抗酸碱腐蚀性能及磁致伸缩性能的影响.结果表明:离子注入渗氮后,(Tb,Dy)Fe2合金表面的REFb相分解,生成了REN,α-Fe和Fe8N新相,材料表面微观形貌发生了明显变化,表面硬度明显提高.通过测试极化曲线研究了渗氮前后(Tb,Dy)Fe2合金在不同PH值NaCl溶液中的抗酸碱腐蚀性能,发现pH值相同条件下渗氮处理后(Tb,Dy) Fe2合金的自腐蚀电位Ecorr较渗氮前明显正移且有钝化现象发生.在加速电压140 kV,离子注入剂量5.0×1017 ion.cm -2条件下渗氮处理的(Tb,Dy)F合金,处于20℃,3.5% NaCl溶液环境中,pH=4时,△Ecorr=0.23413 V; pH =7时,△Ecorr =0.18992 V; pH=10时,△Ecorr =0.01268 V,渗氮处理后(Tb,Dy)Fe2合金的抗酸腐蚀性能明显增强,抗碱腐蚀性能变化不明显.随着pH值的增大,渗氮与未渗氮(Tb,Dy) Fe2合金的抗腐蚀性能均变差.由于离子注入表面渗氮的渗氮层很薄,渗氮温度很低,渗氮处理没有破坏材料的内部基体结构,因此渗氮后材料渗氮处理没有破坏材料的内部基体结构,其磁致伸缩性能几乎未受影响.研究表明离子注入渗氮是(Tb,Dy)Fe2磁致伸缩材料表面改性的一种有效方法.%Effects of nitriding modification on surface phase structure, morphology, case hardness, corrosion resistance and magnetostriction of (Tb,Dy)Fej alloy were investigated by nitrogen ion implantation. The results showed that the surface REFe2 phase decomposed and transformed into REN, α-Fe and Fe8N phases after nitrogen ion implantation. The surface morphology of the alloy had an obvious change, and the case hardness was also greatly improved. The corrosion resistance properties of (Tb,Dy) Fe2 alloy were researched by tested polarization curves in NaCl solutions with different pH value. It was found

  10. Sandwich Magnetoelectric Composites of Polyvinylidene Fluoride, Tb-Dy-Fe Alloy, and Lead Zirconate Titanate

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The novel sandwich composites were prepared by sandwiching a polyvinylidene fluoride/Tb-Dy-Fe alloy composite (PVDF/Terfenol-D) between polyvinylidene fluoride/lead zirconate titanate composites(PVDF/PZT). The maximum magnetoelectric effect voltage coefficient, (dE/dH)33max, of the sandwich composites is higher than that of three-phase composites at their own optimal loading level of Terfenol-D. This is attributed to less interface relaxations of strain and better polarization of the sandwich composites. When the volume fraction of Terfenol-D is higher than 0.10, no coupling interaction for three-phase composites could intensity, the magnetoelectric effect voltage coefficient, (dE/dH)33, of sandwich composites is higher than that of three-phase composites; at low magnetic field intensity, (dE/dH)33 of sandwich composites is lower than that of three-phase composites. At their resonance frequency, the (dE/dH)33max of the sandwich composites and the dH)33max at resonance frequency confirms the improvement of maximum magnetoelectric effect coefficient via sandwich-structured composites.

  11. Structural and magnetic properties of two branches of the tripod-kagome-lattice family A2R3Sb3O14 (A = Mg, Zn; R = Pr, Nd, Gd, Tb, Dy, Ho, Er, Yb)

    Science.gov (United States)

    Dun, Z. L.; Trinh, J.; Lee, M.; Choi, E. S.; Li, K.; Hu, Y. F.; Wang, Y. X.; Blanc, N.; Ramirez, A. P.; Zhou, H. D.

    2017-03-01

    We present a systematic study of the structural and magnetic properties of two branches of the rare-earth tripod-kagome-lattice (TKL) family A2R3Sb3O14 (A = Mg, Zn; R = Pr, Nd, Gd, Tb, Dy, Ho, Er, Yb; here, we use abbreviation A-R, as in MgPr for Mg2Pr3Sb3O14 ), which complements our previously reported work on MgDy, MgGd, and MgEr [Z. L. Dun et al., Phys. Rev. Lett. 116, 157201 (2016), 10.1103/PhysRevLett.116.157201]. The present susceptibility (χdc, χac) and specific-heat measurements reveal various magnetic ground states, including the nonmagnetic singlet state for MgPr, ZnPr; long-range orderings (LROs) for MgGd, ZnGd, MgNd, ZnNd, and MgYb; a long-range magnetic charge ordered state for MgDy, ZnDy, and potentially for MgHo; possible spin-glass states for ZnEr, ZnHo; the absence of spin ordering down to 80 mK for MgEr, MgTb, ZnTb, and ZnYb compounds. The ground states observed here bear both similarities as well as striking differences from the states found in the parent pyrochlore systems. In particular, while the TKLs display a greater tendency towards LRO, the lack of LRO in MgHo, MgTb, and ZnTb can be viewed from the standpoint of a balance among spin-spin interactions, anisotropies, and non-Kramers nature of single-ion state. While substituting Zn for Mg changes the chemical pressure, and subtly modifies the interaction energies for compounds with larger R ions, this substitution introduces structural disorder and modifies the ground states for compounds with smaller R ions (Ho, Er, Yb).

  12. Polymer matrix composite materials reinforced by Tb0.3Dy0.7Fe1.9 magnetostrictive particles

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2009-11-01

    Full Text Available The goal of this work was to describe manufacturing process of polymer matrix composite materials reinforced by Tb0.3Dy0.7Fe1.9 particles and to observe changes of physical properties (magnetic properties and magnetostriction of samples with randomly oriented magnetostrictive particles in epoxy matrix and with aligning these particles in the matrix during fabrication process.Design/methodology/approach: Polymer matrix composite materials reinforced by the Tb0.3Dy0.7Fe1.9 magnetostrictive particles fabricating method was developed during the investigations, making it possible to obtain materials with good physical properties. The influence of the concentration of the Td0.3Dy0.7Fe1.9 particles on magnetic and magnetostrictive properties was estimated. Metallographic examination of powder’s morphology as well as EDS and XRD analysis and observations the structure of composite materials were made.Findings: The influence of magnetic particle alignment is observed in the magnetic and magnetostriction responses. The magnetostrictive response improves when the magnetic particles are oriented in magnetic fields and reaches approximately 184 ppm for oriented composite materials with 25% volume fraction of Td0.3Dy0.7Fe1.9 particles.Practical implications: For potential applications in technological devices, such as sensors and actuators, it is desirable to form composite systems by combining magnetostrictive phases with matrix, in order to have giant magnetostrictive effect and, at the same time, to reduce disadvantages of monolithic material.Originality/value: The originality of this work is based on manufacturing process, especially of applying magnetic alignment for ordering Td0.3Dy0.7Fe1.9 particles during polymerization of epoxy matrix.

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

    Science.gov (United States)

    Okutani, Takeshi; Nagai, Hideaki; Mamiya, Mikito

    2009-04-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

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

    Science.gov (United States)

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

    2016-07-20

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

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

    Science.gov (United States)

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

    2016-07-01

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

  17. Structural, spectral, dielectric and magnetic properties of Tb-Dy doped Li-Ni nano-ferrites synthesized via micro-emulsion route

    Science.gov (United States)

    Junaid, Muhammad; Khan, Muhammad Azhar; Iqbal, F.; Murtaza, Ghulam; Akhtar, Majid Niaz; Ahmad, Mukhtar; Shakir, Imran; Warsi, Muhammad Farooq

    2016-12-01

    Terbium (Tb) and dysprosium (Dy) doped lithium-nickel nano-sized ferrites (Li0.2Ni0.8Tb0.5xDy0.5xFe2-xO4 where x=0.00-0.08) were prepared by micro-emulsion technique. The X-ray diffraction (XRD) patterns confirmed the single phase cubic spinel structure. The lattice constant was increased due to larger ionic radii of Tb3+ and Dy3+ cations. The crystallite size was found in the range 30-42 nm. The FTIR (Fourier transform infrared spectroscopy) spectra revealed two significant absorption bands (~400-600 cm-1) which indicate the formation of cubic spinel structure. The peaking behavior of dielectric parameters was observed beyond 1.5 GHz. The dielectric constant and dielectric loss were found to decrease by the increase of Tb-Dy contents and frequency. The doping of Tb and Dy in Li-Ni ferrites led to increase the coercive field (120-156 Oe). The smaller magnetic and dielectric parameters suggested the possible utility of these nano-materials in switching and microwave devices applications.

  18. Structure and Magnetostriction of (Dy0.7Tb0.3)0.5Pr0.5FexAlloys (1.10≤ x ≤1.85)

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The structure and magnetostriction of R0.5Pr0.5Fex (R = Dy0. 7Tb0.3, 1.10≤ x ≤1.85) alloys were investigated. It was found that the matrix of arc-melting R0.5Pr0.5Fex alloys is the (Dy, Tb, Pr) Fe2 phase with the MgCu2-type cubic structure and the second phase is rare earth-rich phase when x<1.25. In the range of 1.40≤x<1.55, the second phase is (Dy, Tb, Pr)Fe3 and it becomes the main phase when x >1.55. The crystalline structure of mechanically grinding R0.5Pr0.5Fex alloys is similar to that of the arc-melted alloys. The magnetostriction of the alloys increases with increasing Fe content when x ≤1.25 and decreases when x >1.25.

  19. Down-shifting by energy transfer in Tb{sup 3+}/Dy{sup 3+} co-doped zinc phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Caldiño, U., E-mail: cald@xanum.uam.mx [Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, P.O. Box 55-534, México, D.F. 09340 (Mexico); Muñoz H, G.; Camarillo, I. [Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, P.O. Box 55-534, México, D.F. 09340 (Mexico); Speghini, A. [Dipartimento di Biotecnologie, Università di Verona, and INSTM, UdR Verona, Strada Le Grazie 15, I-37314 Verona (Italy); IFAC CNR, Nello Carrara Institute of Applied Physics, MDF Lab, I-50019 Sesto Fiorentino, FI (Italy); Bettinelli, M. [Dipartimento di Biotecnologie, Università di Verona, and INSTM, UdR Verona, Strada Le Grazie 15, I-37314 Verona (Italy)

    2015-05-15

    An optical spectroscopy investigation of zinc phosphate glasses activated with Tb{sup 3+}/Dy{sup 3+} ions is carried out through photoluminescence spectra and decay time measurements. The emission color can be adjusted from yellow–green light, with CIE1931 chromaticity coordinates (0.36,0.44), toward the white light region (0.35,0.39) by decreasing the Tb{sup 3+} content from 1.0 to 0.1 mol% of Tb(PO{sub 3}){sub 3} upon Dy{sup 3+} excitation at 423 nm. Such visible region luminescence is generated by {sup 5}D{sub 4}→{sup 7}F{sub 5} and {sup 5}D{sub 4}→{sup 7}F{sub 3} emissions of Tb{sup 3+} in addition to {sup 4}I{sub 15/2}→{sup 6}H{sub 15/2}, {sup 4}F{sub 9/2}→{sup 6}H{sub 15/2}, {sup 4}F{sub 9/2}→{sup 6}H{sub 13/2} and {sup 4}F{sub 9/2}→{sup 6}H{sub 11/2} emissions of Dy{sup 3+}, so that Tb{sup 3+} emission is sensitized by Dy{sup 3+} through a non-radiative resonant energy transfer. A dominant {sup 5}D{sub 4}→{sup 7}F{sub 5} green emission is observed in detriment of the {sup 5}D{sub 3}→{sup 7}F{sub J} blue emissions upon 282 nm excitation, as well as an extended excitation range (280–500 nm), due to multiple Dy{sup 3+} and Tb{sup 3+} transitions, which might contribute to enhance the spectral response of solar photovoltaic cells by down-shifting of the incident solar spectrum. - Highlights: • Zn(PO{sub 3}){sub 2} glasses are optically activated with Tb{sup 3+}/Dy{sup 3+} (ZPTbDy). • Non-radiative resonant energy transfer takes place between Tb{sup 3+} and Dy{sup 3+}. • Luminescence can be adjusted from yellow–green light toward the white light region. • ZPTbDy phosphor exhibits spectroscopic properties for photovoltaic applications.

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

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

    Bi-ferroic particulate composites with Tb0.2sDy0.72Fe2 (Terfenol-D) particles randomly dispersed in ferroelectric polyvinylidene fluoride matrix prepared by a simple hot-pressing procedure were investigated. With increasing concentration of Terfenol-D, the magnetic susceptibility, saturation magnetization and initial permeability of the composites increases. The dependence of the effective magnetostriction on applied bias for the composites is similar to that for bulk Terfenol-D, but the effective magnetostriction strongly depends on the volume fraction of Terfenol-D. The observed behaviour of the composite is reasonably described by using effective medium theories.

  1. Anisotropy in the paramagnetic phase of RAl/sub 2/ cubic intermetallic compounds (R = Tb, Dy, and Er)

    Energy Technology Data Exchange (ETDEWEB)

    del Moral, A.; Ibarra, M.R.; Abell, J.S.; Montenegro, J.F.D.

    1987-05-01

    In this paper it is shown that the anisotropy in the paramagnetic phase is a useful characteristic when used to single out high-rank susceptibility tensor components in the paramagnetic regime of cubic crystals. Application of this technique to RAl/sub 2/ compounds (R = Tb,Dy,Er) allows the determination of longitudinal and transverse (in the form of linear combinations) fourth- and sixth-rank paramagnetic susceptibilities. The use of the fourth-rank longitudinal susceptibility allows quadrupolar pair interactions in these compounds to be probed.

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

    Science.gov (United States)

    Yusupov, R V; Mertelj, T; Chu, J-H; Fisher, I R; Mihailovic, D

    2008-12-12

    The coupling of phonons with collective modes and single-particle gap excitations associated with one- (1d) and two-directional (2d) electronically driven charge-density wave (CDW) ordering in metallic RTe3 is investigated as a function of rare-earth ion chemical pressure (R=Tb,Dy,Ho) using femtosecond pump-probe spectroscopy. From the T dependence of the CDW gap DeltaCDW and the amplitude mode, we find that while the transition to a 1d-CDW ordered state at Tc1 initially proceeds in an exemplary mean-field-like fashion, below Tc1, DeltaCDW is depressed and departs from the mean-field behavior. The effect is apparently triggered by resonant mode mixing of the amplitude mode with a totally symmetric phonon at 1.75 THz. At low temperatures, when the state evolves into a 2d-CDW ordered state at Tc2 in the DyTe3 and HoTe3, additional much weaker mode mixing is evident but no soft mode is observed.

  3. Synthesis and luminescence properties of BaTiO3:RE (RE = Gd3+, Dy3+, Tb3+, Lu3+) phosphors

    Indian Academy of Sciences (India)

    Esra Korkmaz; Nilgun Ozpozan Kalaycioglu

    2012-11-01

    Gd3+, Dy3+, Tb3+ and Lu3+ doped BaTiO3-based phosphors were synthesized with modified solidstate technique at 1000 °C. The optimization of reaction conditions were carried out by thermogravimetry and differential thermal analysis methods (DTA/TG). The reaction products obtained in an air atmosphere were characterized by X-ray powder diffraction (XRD). Surface and elemental analyses were performed by using an SEM instrument. The excitation and emission spectra were recorded by photoluminescence spectrophotometer (PL). The thermoluminescence (TL) properties of BaTiO3 samples doped with Gd3+, Dy3+, Tb3+ and Lu3+ were investigated.

  4. Crystal field effects in the intermetallic R Ni3Ga9 (R =Tb , Dy, Ho, and Er) compounds

    Science.gov (United States)

    Silva, L. S.; Mercena, S. G.; Garcia, D. J.; Bittar, E. M.; Jesus, C. B. R.; Pagliuso, P. G.; Lora-Serrano, R.; Meneses, C. T.; Duque, J. G. S.

    2017-04-01

    In this paper, we report temperature-dependent magnetic susceptibility, electrical resistivity, and heat-capacity experiments in the family of intermetallic compounds R Ni3Ga9 (R = Tb, Dy, Ho, and Er). Single-crystalline samples were grown using Ga self-flux method. These materials crystallize in a trigonal ErNi3Al9 -type structure with space group R 32 . They all order antiferromagnetically with TNK . The anisotropic magnetic susceptibility presents large values of the ratio χeasy/χhard indicating strong crystalline electric-field (CEF) effects. The evolution of the crystal-field scheme for each R was analyzed in detail by using a spin model including anisotropic nearest-neighbor Ruderman-Kittel-Kasuya-Yosida interaction and the trigonal CEF Hamiltonian. Our analysis allows one to understand the distinct direction of the ordered moments along the series—the Tb-, Dy-, and Ho-based compounds have the ordered magnetic moments in the easy ab plane and the Er sample magnetization easy axis is along the c ̂ direction.

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

    Science.gov (United States)

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

    2016-07-01

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

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

    Science.gov (United States)

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

    2012-02-20

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

  7. Influence of the rare earth concentration on the crystallization process of Fe-Dy-B amorphous alloys. Study of Fe74Dy6B20 and Fe70Dy10B20 alloys

    Science.gov (United States)

    Ravach, G.; Machizaud, F.; Teillet, J.; LeBreton, J. M.; Fnidiki, A.

    2000-04-01

    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.%.

  8. Heteronuclear Ni(ii)-Ln(iii) (Ln = La, Pr, Tb, Dy) complexes: synthesis and single-molecule magnet behaviour.

    Science.gov (United States)

    Upadhyay, Apoorva; Das, Chinmoy; Langley, Stuart K; Murray, Keith S; Srivastava, Anant K; Shanmugam, Maheswaran

    2016-02-28

    The reaction of hydrated nickel(II) salts (chloride or nitrate) and hydrated lanthanide nitrate salts with the Schiff base ligand 2-methoxy-6-[(E)-phenyliminomethyl] phenol (HL) in methanol resulted in the isolation of three isostructural linear heterometallic trinuclear complexes and a heterometallic tetranuclear complex. The molecular structures of these complexes were determined via single crystal X-ray diffraction revealing molecular structures of formulae [Ni2La(L-)6](NO3)0.55(OH)0.45 (1), [Ni2Pr(L-)6](NO3)0.48(OH)0.52 (2), [Ni2Tb(L-)6](NO3)0.5(Cl)0.5 (3) and [Ni2Dy2(L-2(o-vanillin)2(CO3)2(NO3)2(MeOH)2] (4). Structural analysis for 1-3 reveals that the lanthanide ion is sandwiched between two Ni(II) ions and the Ni⋯Ln⋯Ni metallic core displays a linear arrangement, with an average ∠Ni⋯Ln⋯Ni bond angle of 179.7°. Analysis of 4 reveals the metal ions are arranged such that two Ni-Dy subunits are bridged by two carbonate ligands via the Dy sites. Direct current magnetic susceptibility measurements for complexes 1-4 reveal that the Ni(II) ions are coupled ferromagnetically with the Tb(III) (3) and Dy(III) (4) ions, and antiferromagnetically with the Pr(III) ion (2). For complex 1 a long range intramolecular ferromagnetic interaction is witnessed between the Ni(II) ions (Ni⋯Ni = 6.873(9) Å) via a closed shell La(III) ion. The magnetic data of 1 were fitted using the HDVV Hamiltonian revealing the following parameters; J = +0.46 cm(-1), g = 2.245, D = +4.91 cm(-1). Alternating current magnetic susceptibility measurements performed on complexes 2-4 revealed that 3 and 4 displayed frequency dependent χ′′M signals (Hac = 3.5 Oe and Hdc = 0 Oe) which is a characteristic signature of a single-molecule magnet behaviour.

  9. Investigation on the Microstructure, Texture and Magnetostriction of Directionally Solidified Tb0.3Dy0.7Fe1.95−xVx Alloys

    Directory of Open Access Journals (Sweden)

    J. Arout Chelvane

    2012-01-01

    Full Text Available Effect of V addition on the microstructure and magnetostriction of directionally solidified Tb0.3Dy0.7Fe1.95 has been investigated. The microstructure of V added alloys (Tb0.3Dy0.7Fe1.95−xVx with x=0, 0.025, 0.05, and 0.075 indicate that Fe-50 at.% V is formed as primary phase, which subsequently undergoes spinodal decomposition. The spinodially decomposed Fe-rich phase reacts with the liquid and forms the matrix phase, (Tb,DyFe2. The V-rich spinodally decomposed product, on the other hand, exists as remnant phase without undergoing any metallurgical transformation. Texture studies indicate that the grains of (Tb,DyFe2 show 〈110〉/rotated 〈110〉 and 〈112〉 orientations for all compositions investigated in the directionally solidified condition. An improvement in magnetostriction has been noticed for small addition of V (x=0.025 and with further addition the magnetostrictive property decreases. The formation of additional phases containing vanadium is attributed to be the reason when V is added in higher concentration (x>0.025 levels.

  10. Hydrothermal synthesis, characterization, and luminescence of Ca2B2O5:RE (RE = Eu3+, Tb3+, Dy3+) nanofibers

    Science.gov (United States)

    Yang, Li; Wan, Yingpeng; Li, Yuze; Pu, Yinfu; Huang, Yanlin; Chen, Cuili; Seo, Hyo Jin

    2016-04-01

    Ca2B2O5:RE (RE = Eu3+, Tb3+, Dy3+) nanofibers were synthesized by the hydrothermal reaction method. The structural refinement was conducted on the base of the X-ray powder diffraction (XRD) measurements. The surface properties of the Ca2B2O5:RE (RE = Eu3+, Tb3+, Dy3+) nanofibers were investigated by the measurements such as the scanning electron microscope (SEM), transmission electron microscope (TEM), and the energy dispersive spectrum (EDS). The nanofiber has a diameter of about 100 nm and a length of several micrometers. The luminescence properties such as photoluminescence excitation (PLE) and emission spectra (PL), decay lifetime, color coordinates, and the absolute internal quantum efficiency (QE) were reported. Ca2B2O5:Eu3+ nanofibers show the red luminescence with CIE coordinates of ( x = 0.41, y = 0.51) and the luminescence lifetime of 0.63 ms. The luminescence of Ca2B2O5:Tb3+ nanofibers is green color ( x = 0.29, y = 0.53) with the lifetime of 2.13 ms. However, Dy3+-doped Ca2B2O5 nanofibers present a single-phase white-color phosphor with the fluorescence decay of 3.05 ms. Upon near-UV excitation, the absolute quantum efficiency is measured to be 65, 35, and 37 % for Eu3+-, Tb3+-, Dy3+-doped Ca2B2O5 nanofibers, respectively. It is suggested that Ca2B2O5:RE (RE = Eu3+, Tb3+, Dy3+) nanofibers could be an efficient phosphor for lighting and display.

  11. Large dielectric permittivity in the paraelectric RMn2O5 with R=Tb, Dy, and Er

    Science.gov (United States)

    Han, T. C.; Lin, J. G.; Kuo, K. M.; Chern, G.

    2008-04-01

    The complex dielectric permittivities (ɛ',ɛ″) of RMn2O5 (R =Tb, Dy, and Er) are measured in the temperature range of 78-328 K with frequencies ranging from 100 Hz to 1 MHz. A large real part of the dielectric constant ɛ' (40-140) is observed at room temperature in all three samples studied. These values are higher than the peak value found at the ferroelectric transition of RMn2O5 single crystals. Our results reveal that high dielectric permittivities are related to thermally activated dipolar motions with activation energies of ˜300 meV and a relaxation frequency of ˜3×1012 Hz. The possible relation between the high dielectric permittivity and the size effect of R ions based on the spin-phonon interaction is suggested.

  12. Domain Rotation Simulation of the Magnetostriction Jump Effect of 〈110〉 Oriented TbDyFe Crystals

    Institute of Scientific and Technical Information of China (English)

    ZHANG Chang-Sheng; MA Tian-Yu; PAN Xing-Wen; YAN Mi

    2012-01-01

    The compressive pre-stress induced magnetostriction jump effect of an [-110] oriented TbDyFe crystal is simulated by tracking the initial redistribution of magnetic domains and their volume fraction evolutions under external magnetic fields. Through searching for the free energy minima within both (-110) and (110) planes, it is found that the axial compressive pre-stress not only switches magnetizations of the 35° domains toward the perpendicular plane, but also switches magnetizations of the 90° domains approaching the [110] direction. When increasing the stress magnitude, the volume fraction for 35° domains decreases and the one for the [110] domain increases rapidly. However, the volume fraction for the four 90° domains within the perpendicular plane first increases to a maximum under a certain stress magnitude and further decreases. The stress-induced anisotropy thereafter changes the volume fraction evolutions during the magnetization process, which explains well the magnetostriction jump effect.%The compressive pre-stress induced magnetostriction jump effect of an [(-1) 10] oriented TbDyFe crystal is simulated by tracking the initial redistribution of magnetic domains and their volune fraction evolutions under external magnetic fields.Through searching for the free energy minima within both ((-1) 10) and (110) planes,it is found that the axial compressive pre-stress not only switches magnetizations of the 35° domains toward the perpendicular plane,but also switches magnetizations of the 90° domains approaching the [110] direction.When increasing the stress magnitude,the volume fraction for 35° domains decreases and the one for the [110] domain increases rapidly.However,the volume fraction for the four 90° domains within the perpendicular plane first increases to a maximum under a certain stress magnitude and further decreases.The stress-induced anisotropy thereafter changes the volume fraction evolutions during the magnetization process,which explains

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

    Science.gov (United States)

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

    2016-06-01

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

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

    Science.gov (United States)

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

    2015-02-14

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

  15. Magnetocaloric properties of rare-earth substituted DyCrO3

    Science.gov (United States)

    McDannald, A.; Jain, M.

    2015-07-01

    Recently, there has been a focus on the need for efficient refrigeration technology without the use of expensive or harmful working fluids, especially at temperatures below 30 K. Solid state refrigeration, based on the magnetocaloric effect, provides a possible solution to this problem. The rare-earth chromites (RCrO3), especially DyCrO3, with its large magnetic moment dysprosium ion, are potential candidates for such an application. The Dy3+ ordering transition at low temperatures (cooling power of 237 J/kg at 40 kOe and 5 K) indicates that this material system is well suited for low temperature (<30 K) solid state refrigeration applications.

  16. Tunable multicolor and white luminescence in Tb{sup 3+}/Dy{sup 3+}/Mn{sup 2+} doped CePO{sub 4} via energy transfer

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Zhigao [School of Materials Science and Engineering, Key Laboratory of Low-dimensional Materials and Application Technology (Ministry of Education), Xiangtan University, Xiangtan 411105 (China); Lu, Wei [University Research Facility in Materials Characterization and Device Fabrication, The Hong Kong Polytechnic University (Hong Kong); Zeng, Songjun, E-mail: songjunz@hunnu.edu.cn [College of Physics and Information Science and Key Laboratory of Low-dimensional Quantum Structures and Quantum Control of the Ministry of Education, Hunan Normal University, Changsha 410081, Hunan (China); Wang, Haibo; Rao, Ling [School of Materials Science and Engineering, Key Laboratory of Low-dimensional Materials and Application Technology (Ministry of Education), Xiangtan University, Xiangtan 411105 (China); Li, Zheng, E-mail: lizheng@xtu.edu.cn [School of Materials Science and Engineering, Key Laboratory of Low-dimensional Materials and Application Technology (Ministry of Education), Xiangtan University, Xiangtan 411105 (China)

    2015-07-15

    Highlights: • Tb{sup 3+}/Dy{sup 3+}/Mn{sup 2+} doped CePO{sub 4} DCNPs were prepared by a one-pot hydrothermal process. • The PL properties and the ET mechanism of these DCNPs were investigated in detail. • These DCNPs exhibit tunable multi-color output under UV excitation. • Intense white emissions can be realized by singly doping Dy{sup 3+} and Mn{sup 2+} in CePO{sub 4} host. - Abstract: In this paper, a series of Tb{sup 3+}/Dy{sup 3+}/Mn{sup 2+} doped CePO{sub 4} downconversion nanophosphors (DCNPs) were prepared by a one-pot hydrothermal process. The obtained DCNPs presented monoclinic and hexagonal phase structure with wire-like shape. The photoluminescence (PL) properties and the energy transfer (ET) mechanism of these DCNPs were investigated in detail. The ET mechanism of Ce{sup 3+}/Tb{sup 3+} in CePO{sub 4} host was calculated by means of concentration quenching and spectral overlapping, and calculation results revealed that dipole–dipole interactions should be more responsible. The maximum value of ET efficiency was measured to 87.4% for Tb{sup 3+} doped CePO{sub 4} system. In addition, owing to the efficient ET between Ce{sup 3+} and Tb{sup 3+}/Dy{sup 3+}/Mn{sup 2+}, these as-prepared DCNPs exhibit tunable multi-color output under ultra-violet (UV) light excitation. More importantly, the intense cold and warm white emissions can be realized by singly doping 2%Dy{sup 3+} and 20%Mn{sup 2+} in CePO{sub 4} host under UV irradiation, respectively. The corresponding CIE 1931 coordinates were calculated to be (0.30, 0.30) and (0.30, 0.32), respectively, which are closed to the standard white emission (0.33, 0.33). These findings demonstrate the efficient white light emission by singly doped Dy{sup 3+} or Mn{sup 2+} in CePO{sub 4} system for the first time, which is different from commonly used co-doped or tri-doped system. The multicolor tuning and white emission make these Tb{sup 3+}/Dy{sup 3+}/Mn{sup 2+} doped CePO{sub 4} DCNPs potential phosphors in

  17. A Multifunctional Tb-MOF for Highly Discriminative Sensing of Eu(3+) /Dy(3+) and as a Catalyst Support of Ag Nanoparticles.

    Science.gov (United States)

    Xu, Guo-Wang; Wu, Ya-Pan; Dong, Wen-Wen; Zhao, Jun; Wu, Xue-Qian; Li, Dong-Sheng; Zhang, Qichun

    2017-06-01

    Exploring novel multifunctional rare earth materials is very important because these materials have fundamental interests, such as new structural facts and connecting modes, as well as potential technological applications, including optics, magnetic properties, sorption, and catalytic behaviors. Especially, employing these nanomaterials for sensing or catalytic reactions is still very challenging. Herein, a new superstable, anionic terbium-metal-organic-framework, [H2 N(CH3 )2 ][Tb(cppa)2 (H2 O)2 ], (China Three Gorges University (CTGU-1), H2 cppa = 5-(4-carboxyphenyl)picolinic acid), is successfully prepared, which can be used as a turn-on, highly-sensitive fluorescent sensor to detect Eu(3+) and Dy(3+) , with a detection limitation of 5 × 10(-8) and 1 × 10(-4) m in dimethylformamide, respectively. This result represents the first example of lanthanide-metal-organic-frameworks (Ln-MOF) that can be employed as a discriminative fluorescent probe to recognize Eu(3+) and Dy(3+) . In addition, through ion exchanging at room temperature, Ag(I) can be readily reduced in situ and embedded in the anionic framework, which leads to the formation of nanometal-particle@Ln-MOF composite with uniform size and distribution. The as-prepared Ag@CTGU-1 shows remarkable catalytic performance to reduce 4-nitrophenol, with a reduction rate constant κ as large as 2.57 × 10(-2) s(-1) ; almost the highest value among all reported noble-metal-nanoparticle@MOF composites. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Mo{sub 2}NiB{sub 2}-type (Gd, Tb, Dy){sub 2}Ni{sub 2.35}Si{sub 0.65} and La{sub 2}Ni{sub 3}-type (Dy, Ho){sub 2}Ni{sub 2.5}Si{sub 0.5} compounds: Crystal structure and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Morozkin, A.V., E-mail: morozkin@tech.chem.msu.ru [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, Moscow 119992, GSP-2 (Russian Federation); Isnard, O. [CNRS, Insitut. Néel, 25 rue des Martyrs BP166, F-38042 Grenoble (France); Université Grenoble Alpes, Inst. Néel, F-38042 Grenoble (France); Nirmala, R. [Indian Institute of Technology Madras, Chennai 600 036 (India); Malik, S.K. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59082-970 (Brazil)

    2015-05-15

    The crystal structure of new Mo{sub 2}NiB{sub 2}-type (Gd, Tb, Dy){sub 2}Ni{sub 2.35}Si{sub 0.65} (Immm, No. 71, oI10) and La{sub 2}Ni{sub 3}-type (Dy, Ho){sub 2}Ni{sub 2.5}Si{sub 0.5} (Cmce No. 64, oC20) compounds has been established using powder X-ray diffraction studies. Magnetization measurements show that the Mo{sub 2}NiB{sub 2}-type Gd{sub 2}Ni{sub 2.35}Si{sub 0.65} undergoes a ferromagnetic transition at ~66 K, whereas isostructural Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} shows an antiferromagnetic transition at ~52 K and a field-induced metamagnetic transition at low temperatures. Neutron diffraction study shows that, in zero applied field, Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} exhibits c-axis antiferromagnetic order with propagation vector K=[1/2, 0, 1/2] below its magnetic ordering temperature and Tb magnetic moment reaches a value of 8.32(5) μ{sub B} at 2 K. The La{sub 2}Ni{sub 3}-type Dy{sub 2}Ni{sub 2.5}Si{sub 0.5} exhibits ferromagnetic like transition at ~42 K with coexisting antiferromagnetic interactions and field induced metamagnetic transition below ~17 K. The magnetocaloric effect of Gd{sub 2}Ni{sub 2.35}Si{sub 0.65}, Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} and Dy{sub 2}Ni{sub 2.5}Si{sub 0.5} is calculated in terms of isothermal magnetic entropy change and it reaches a maximum value of −14.3 J/kg K, −5.3 J/kg K and −10.3 J/kg K for a field change of 50 kOe near 66 K, 52 K and 42 K, respectively. Low temperature magnetic ordering with enhanced anisotropic effects in Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} and Dy{sub 2}Ni{sub 2.35}Si{sub 0.65} is accompanied by a positive magnetocaloric effect with isothermal magnetic entropy changes of +12.8 J/kg K and ~+9.9 J/kg K, respectively at 7 K for a field change of 50 kOe. - Graphical abstract: The (Gd, Tb, Dy){sub 2}Ni{sub 2.35}Si{sub 0.65} supplement the series of Mo{sub 2}NiB{sub 2}-type rare earth compounds, whereas the (Dy, Ho){sub 2}Ni{sub 2.5}Si{sub 0.5} supplement the series of La{sub 2}Ni{sub 3}-type rare

  19. Predictable self-assembled [2×2] Ln(III)4 square grids (Ln = Dy,Tb)-SMM behaviour in a new lanthanide cluster motif.

    Science.gov (United States)

    Anwar, Muhammad Usman; Thompson, Laurence Kenneth; Dawe, Louise Nicole; Habib, Fatemah; Murugesu, Muralee

    2012-05-14

    The ditopic carbohydrazone ligand (L1) produces the square, self-assembled [2×2] grids [Dy(4)(L1)(4)(OH)(4)]Cl(2) (1) and [Ln(4)(L1)(4)(μ(4)-O)(μ(2)-1,1-N(3))(4)] (Ln = Dy (2), Tb (3)), with 2 exhibiting SMM behaviour. Two relaxation processes occur with U(eff) = 51 K, 91 K in the absence of an external field, and one with U(eff) = 270 K in the presence of a 1600 Oe optimum field.

  20. Preparation and photoluminescence characteristics of Tb-, Sm- and Dy-doped Y{sub 2}O{sub 3} nanofibers by electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Li Xiaoyan; Chen Yuming [College of Chemistry and Materials Science, College of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007 (China); Fujian Modified Plastic Institute of Research and Technology Development, Fuzhou 350007 (China); Fujian Engineering Research Center of Environment-friendly Polymer Material, Fuzhou 350007 (China); Qian Qingrong, E-mail: qrqian@fjnu.edu.cn [College of Chemistry and Materials Science, College of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007 (China); Fujian Modified Plastic Institute of Research and Technology Development, Fuzhou 350007 (China); Fujian Engineering Research Center of Environment-friendly Polymer Material, Fuzhou 350007 (China); Liu Xinping; Xiao Liren [College of Chemistry and Materials Science, College of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007 (China); Fujian Modified Plastic Institute of Research and Technology Development, Fuzhou 350007 (China); Fujian Engineering Research Center of Environment-friendly Polymer Material, Fuzhou 350007 (China); Chen Qinghua, E-mail: cqhuar@pub5.fz.fj.cn [College of Chemistry and Materials Science, College of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007 (China); Fujian Modified Plastic Institute of Research and Technology Development, Fuzhou 350007 (China); Fujian Engineering Research Center of Environment-friendly Polymer Material, Fuzhou 350007 (China)

    2012-01-15

    An electrospinning-calcination strategy was established to fabricate Y{sub 2}O{sub 3} nanofibers doped with rare earth ions (Tb, Sm and Dy) using electrospun PVA/RE(NO{sub 3}){sub x}/Y(NO{sub 3}){sub 3} composite nanofibers as precursors (x=3.4). The prepared nanofibers were characterized by XRD, FESEM, EDS, (HR)TEM and PL analyses. Based on the experimental results, a solid-solid growth mechanism (SS) was proposed to describe the formation of inorganic crystalline fibers from organic/inorganic composite nanofibers by calcination. It was determined that carbonaceous nanoparticles that were formed in the process of pre-carbonization adsorbed Y{sub 2}O{sub 3}:RE nanoparticles to grow Y{sub 2}O{sub 3}:RE crystal, and the resultant nanofibers exhibited a typical crystalline domain with grain boundary. The obtained Y{sub 2}O{sub 3}:RE nanofibers possessed excellent luminescent characteristics and could be used as an appreciable luminescent material. - Highlights: > Fabricate Y{sub 2}O{sub 3}:RE fibers by the calcination of electrospun PVA/Y(NO{sub 3}){sub 3}/RE(NO{sub 3}){sub 3} composite nanofibers. > Prepared Y{sub 2}O{sub 3}:RE nanofibers display more intensive photoluminescence performance than the bulk materials. > Propose a solid-solid growth mechanism for the formation of inorganic crystalline fibers via calciation.

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

    Science.gov (United States)

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

    2014-04-07

    Reactions of Ln(III) perchlorate (Ln = Gd, Tb, Dy, and Ho), NiCl2·6H2O, and a polydentate Schiff base resulted in the assembly of novel isostructural hexanuclear Ni4Ln2 complexes [Ln = Gd (1), Tb (2), Dy (3), Ho (4)] with an unprecedented 3d-4f metal topology consisting of two defect-dicubane units. The corresponding Ni4Y2 (5) complex containing diamagnetic Y(III) atoms was also isolated to assist the magnetic studies. Interestingly, complexes 2 and 3 exhibit SMM characteristics and 4 shows slow relaxation of the magnetization. The absence of frequency-dependent in-phase and out-of-phase signals for the Ni-Y species suggests that the Ln ions' contribution to the slow relaxation must be effectual as previously observed in other Ni-Dy samples. However, the observation of χ″ signals with zero dc field for the Ni-Tb and Ni-Ho derivatives is notable. Indeed, this is the first time that such a behavior is observed in the Ni-Tb and Ni-Ho complexes.

  2. Luminescent investigations of Li{sub 6}Lu(BO{sub 3}){sub 3}:Tb{sup 3+}, Dy{sup 3+} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Fawad, U.; Oh, Myeongjin; Park, H. [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Kim, Sunghwan [Department of Radiological Science, Cheongju University, Cheongju 360-764 (Korea, Republic of); Kim, H.J., E-mail: hongjoo@knu.ac.kr [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of)

    2014-10-15

    Highlights: • New Li{sub 6}Lu(BO{sub 3}){sub 3}:Tb{sup 3+}, Dy{sup 3+} phosphors were fabricated by solid state reaction method. • Li{sub 6}Lu(BO{sub 3}){sub 3}:Dy{sup 3+} emissions; 481, 578, 666 and 734 nm (λ{sub ex} = 350 nm) and for. • Li{sub 6}Lu(BO{sub 3}){sub 3}:Tb{sup 3+}; 488–492, 543–551, 578–599, 614–629 and 651–688 nm (λ{sub ex} = 305 nm). • Light yield of Li{sub 6}Lu(BO{sub 3}){sub 3}:Tb{sup 3+}; 75% while for Li{sub 6}Lu(BO{sub 3}){sub 3}:Dy{sup 3+} is 19% of PDP. • The decay time measured for Li{sub 6}Lu(BO{sub 3}){sub 3}:Tb{sup 3+} phosphor was 1.38 ms. - Abstract: In our novel work we report the luminescence properties of Terbium (Tb{sup 3+}) and Dysprosium (Dy{sup 3+}) ions in Li{sub 6}Lu(BO{sub 3}){sub 3} (lithium lutetium borate) phosphors with its specific and productive use in various luminescent display systems. We have synthesized Tb{sup 3+} and Dy{sup 3+} doped Li{sub 6}Lu(BO{sub 3}){sub 3} phosphors by the solid state reaction method. Concentration based optimization of activators is attained i.e. 2 mol% for Tb{sup 3+} and 5 mol% for Dy{sup 3+}. XRD (X-ray diffraction) and FE-SEM (Field emission-scanning electron microscopy) were used to analyze the overall morphologies, crystalline structures and the grain sizes of the prepared phosphors. Moreover, the grain size of 20 μm is confirmed via Scherrer’s formula. In order to characterize the luminescence properties of the synthesized phosphors, we measured its X-ray induced luminescence, proton induced luminescence and UV induced photoluminescence. Under UV luminescence Dy{sup 3+} doped phosphor, it displayed seven obvious peaks corresponding to transitions from {sup 6}H{sub 15/2} (f{sup 9}) ground state to higher energy state of 4f{sup 9} whereas, UV-emission spectrum of Li{sub 6}Lu(BO{sub 3}){sub 3}:Tb{sup 3+} phosphor has shown five major transitions with each peak consists of several smaller lines, confirming the complicated transition ({sup 5}D{sub j} → {sup 7}F

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

    Energy Technology Data Exchange (ETDEWEB)

    Ranke, P.J. von, E-mail: von.ranke@uol.com.br [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil); Nóbrega, E.P. [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil); Caldas, A. [Sociedade Unificada de Ensino Superior e Cultura, SUESC, 20211-351 Rio de Janeiro, RJ (Brazil); Alho, B.P. [Instituto de Aplicação Fernando Rodrigues da Silveira, Universidade do Estado do Rio de Janeiro, Rua Santa Alexandrina, 288, 20260-232 RJ (Brazil); Ribeiro, P.O.; Alvarenga, T.S.T.; Lopes, P.H.O.; Sousa, V.S.R. de [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil); Carvalho, A. Magnus G. [Laboratório Nacional de Luz Síncrotron, CNPEM, 13083-970 Campinas, SP (Brazil); Oliveira, N.A. de [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil)

    2014-11-15

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

  4. Relationship between crystal growth mode, preferred orientation and magnetostriction of (Tb0.3Dy0.7)Fe1.95 alloys

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shirong; LI Kuoshe; YU Dunbo; LI Yongsheng; YANG Hongchuan; LI Hongwei; TU Ganfeng

    2008-01-01

    The relationship between crystal growth mode, preferred orientation and magnetostrictive properties of (Tb0.3Dy0.7)Fe1.95 alloys was investigated at different directional solidification rates. The results showed that preferred orientation had a strong influence on the characteristics of (Tb0.3Dy0.7)Fe1.95 alloys. At lower solidification rates, the sample with preferred orientation showed larger low-field magnetostriction and apparent compressive stress effect. The excessive solidification rate resulted in failure of preferred orientation and a poor magnetostrictive performance. With an increase in solidification rates, the crystal growth modes changed gradually from cellular and primary dendrite morphology to developed dendritic morphology. In addition, domain configurations were observed using magnetic force microscopy, and the change of magnetostrictive properties was interpreted in terms of revealing the domain configurations.

  5. High - pressure synchrotron x-ray diffraction study of RMnO3 (R = Eu, Gd, Tb and Dy) upto 50 GPa

    Science.gov (United States)

    Muthu, D. V. S.; Midgley, A. E.; Scott, P. R.; Kruger, M. B.; Sahu, J. R.; Sood, A. K.; Rao, C. N. R.

    2012-07-01

    We have carried out synchrotron based high-pressure x-ray diffraction study of orthorhombic EuMnO3, GdMnO3, TbMnO3 and DyMnO3 up to 54.4, 41.6, 47.0 and 50.2 GPa, respectively. The diffraction peaks of all the four manganites shift monotonically to higher diffraction angles and the crystals retain the orthorhombic structure till the highest pressure. We have fitted the observed volume versus pressure data with the Birch-Murnaghan equation of state and determined the bulk modulus to be 185 ± 6 GPa, 190 ± 16 GPa, 188 ± 9 GPa and 192 ± 8 GPa for EuMnO3, GdMnO3, TbMnO3 and DyMnO3, respectively. The bulk modulus of EuMnO3 is comparable to other manganites, in contrast to theoretical predictions.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-02-27

    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

  7. Effect of Addition of Al on Crystal Structure Microtexture and Magnetostriction Coefficient in Tb0.3 Dy0.7 Fe1.95 Alloy

    Institute of Scientific and Technical Information of China (English)

    Jiang Liping; Zhao Zengqi; Wu Shuangxia; Huang Jimin; Zuo Liang

    2004-01-01

    The effect of addition of A1 on crystal structure microtexture and magnetostrictioncoefficient in Tb0.3Dy0.7Fe1.95 alloy were studied.The results show that addition of A1 does not change crystal structure of alloy and the precipitates increase in the microtexture as addition of A1 increases.At a certain magnetic field, magnetostriction coefficient decreased as addition of Al increased.

  8. Effect of cooling rate on magnetostriction gradients of Tb0.27Dy0.73Fe1.95 alloys solidified in high magnetic field gradients

    Directory of Open Access Journals (Sweden)

    Tie Liu

    2016-05-01

    Full Text Available In this work, Tb0.27Dy0.73Fe1.95 alloys were solidified in a high magnetic field gradient (8.8 T, -565 T2/m at various cooling rates. Changes in the magnetostriction, crystal orientation, and magnetization of the alloys were investigated. The application of the magnetic field gradient has a strong influence on the magnetostrictive performance. At lower cooling rates, the maximum magnetostriction increases gradually with depth from the top surface of the alloys. However, the effect of the magnetic field gradient is strongly dependent on the cooling rate. With increasing cooling rate, the magnetostriction gradient decreases. The magnetization measurement shows that the saturation magnetization at lower cooling rates increases gradually with depth from the top surface of the alloys. However, with increasing cooling rate, the increase in the saturation magnetization is reduced. The XRD measurement results show that the orientation behavior of the (Tb, DyFe2 phase exhibits a continuous change throughout the alloys at lower cooling rates, but is almost unchanged at higher cooling rates. The change in the magnetostriction of the alloys can be attributed to the changes in crystal orientation and the amount of the (Tb, DyFe2 phase in the alloys caused by both the magnetic field gradient and cooling rate.

  9. Mossbauer effect studies of Tb0.27Dy0.73(Fe1−Co)2 intermetallics at 295 K

    Indian Academy of Sciences (India)

    W Bodnar; M Szklarska-Lukasik; P Stoch; P Zachariasz; J Pszczola; J Suwalski

    2010-09-01

    The synthesis of materials and the studies of crystal structure and 57Fe Mössbauer effect were performed for Tb0.27Dy0.73 (Fe1−Co)2 intermetallics. Terfenol-D (Tb0.27Dy0.73Fe2) is the starting compound of this Fe/Co-substituted series. X-ray measurements showed evidence of a pure cubic Laves phase C15, MgCu2-type, and unit cell parameters were determined across the series. A Co substitution introduced local area, at sub-nanoscale, with random Fe/Co neighbourhoods of the 57Fe atoms. Mössbauer effect spectra for the Tb0.27Dy0.73 (Fe1−Co)2 series at room temperature are composed of a number of locally originated subspectra due to the random distribution of Fe and Co atoms in the transition metal sublattice, and due to [1 1 1] an easy axis of magnetization. Isomer shift, magnetic hyperfine field and quadrupole interaction parameter were obtained from the spectra, both for the local area and for the bulk sample. As a result of Fe/Co substitution, a Slater–Pauling-type curve for the average magnetic hyperfine field vs. Co content was observed. It was found that the magnetic hyperfine fields corresponding to the local area also create a dependence of the Slater–Pauling-type vs. Co contribution in the Fe/Co neighbourhoods.

  10. Pressure-induced enhancement of ferroelectricity in multiferroic RMn2O5 (R=Tb,Dy,Ho)

    Science.gov (United States)

    Dela Cruz, C. R.; Lorenz, B.; Sun, Y. Y.; Wang, Y.; Park, S.; Cheong, S.-W.; Gospodinov, M. M.; Chu, C. W.

    2007-11-01

    Measurements of ferroelectric polarization and dielectric constant were done on RMn2O5 (R=Tb,Dy,Ho) with applied hydrostatic pressures of up to 18kbar . At ambient pressure, distinctive anomalies were observed in the temperature profile of both physical properties at critical temperatures marking the onset of long range antiferromegnetic order (TN1) and ferroelectricity (TC1) , as well as at temperatures when anomalous changes in the polarization, dielectric constant, and spin wave commensurability have been previously reported. In particular, the step in the dielectric constant at low temperatures (TC2) , associated with both a drop in the ferroelectric polarization and an incommensurate magnetic structure, was shown to be suddenly quenched upon passing an R -dependent critical pressure. This was shown to correlate with the stabilization of the high ferroelectric polarization state, which is coincident with the commensurate magnetic structure. The observation is suggested to be due to a pressure-induced phase transition into a commensurate magnetic structure, as exemplified by the pressure-temperature (p-T) phase diagrams constructed in this work. The p-T phase diagrams are determined for all three compounds.

  11. Strong paramagnetic crystalline LnVO{sub 4} (Ln: Gd, Tb, Dy, Ho, Er) nanoparticles synthesized by a fabricating method

    Energy Technology Data Exchange (ETDEWEB)

    Bulbul, Berna; Beyaz, Seda, E-mail: sedacan@balikesir.edu.tr

    2016-04-15

    Strong paramagnetic lanthanide orthovanadate (LnVO{sub 4}, Ln: Gd, Tb, Dy, Ho, Er) nanoparticles were synthesized under ambient conditions by a novel precipitation method that is economical and fabricating. To the X-ray diffraction patterns, all samples are well-crystallized zircon type orthovanadate and have pure tetragonal phase. Their crystal sizes increased from 12.58 to 15.12 nm with increasing the ionic radii of lanthanide. As confirmed with the surface observation by a transmission electron microscope, it was identified that their two-dimensional projection is an ellipse with the two major axes. It was seen that the sizes of nanoparticles (14.40nm-70.69 nm) were bigger than the crystal sizes because of their polycrystalline structures. Besides, the particle sizes increased with reduction of ionic radii of lanthanide. The magnetic properties obtained from a vibrating sample magnetometer revealed that all nanoparticles are strong paramagnetic at room temperature showing an increase in molar susceptibility up to 4.79 × 10{sup −1} cm{sup 3} mol{sup −1}. Such highly crystalline, small and paramagnetic nanoparticles could be thought to be convenient for biomedical applications. - Highlights: • A general fabricating method for lanthanide orthovanadate nanoparticles is proposed. • The method generates highly small and crystalline nanoparticles. • The reduction in ionic radius of lanthanide (Ln{sup 3+}) causes to increase particle size.

  12. Magnetocaloric properties of rare-earth substituted DyCrO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    McDannald, A. [Material Science and Engineering Department, University of Connecticut, Storrs, Connecticut 06269 (United States); Jain, M., E-mail: menka.jain@uconn.edu [Institute of Material Science, University of Connecticut, Storrs, Connecticut 06269 (United States); Department of Physics, University of Connecticut, Storrs, Connecticut 06269 (United States)

    2015-07-28

    Recently, there has been a focus on the need for efficient refrigeration technology without the use of expensive or harmful working fluids, especially at temperatures below 30 K. Solid state refrigeration, based on the magnetocaloric effect, provides a possible solution to this problem. The rare-earth chromites (RCrO{sub 3}), especially DyCrO{sub 3}, with its large magnetic moment dysprosium ion, are potential candidates for such an application. The Dy{sup 3+} ordering transition at low temperatures (<10 K) likely causes a large magnetocaloric response in this material. This study investigates the possibility of tuning the magnetocaloric properties through the use of rare-earth substitution. Both Y{sup 3+} and Ho{sup 3+} substitutions were found to decrease the magnetocaloric response by disrupting the R{sup 3+} ordering. Whereas Er{sup 3+} substitution was found to increase the magnetocaloric response, likely due to an increase in the R{sup 3+} ordering temperature. The large magnetocaloric entropy change of Er{sup 3+} substituted DyCrO{sub 3} (10.92 J/kg K with a relative cooling power of 237 J/kg at 40 kOe and 5 K) indicates that this material system is well suited for low temperature (<30 K) solid state refrigeration applications.

  13. Metathesis synthesis, characterization, spectral and photoactivity studies of Ln2/3MoO4 (Ln=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er and Y)

    Institute of Scientific and Technical Information of China (English)

    Radha Velchuri; Suresh Palla; G. Ravi; Naveen Kumar Veldurthi; J.R. Reddy; M. Vithal

    2015-01-01

    Rare earth ortho-oxomolybdates of composition Ln2/3MoO4 (Ln=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er and Y) were prepared by metathesis reaction. All these materials were characterized by powder X-ray diffraction, Fourier transform-infrared spectroscopy (FT-IR) and UV-Vis diffuse reflectance spectra. The Rietveld analysis of all the samples was carried out to obtain the unit cell pa-rameters and reliability factors. All the materials were crystallized in tetragonal lattice withI41/a space group. The infrared spectra of all the samples were characterized by bands due to MoO42– units. The bandgap energies of all the samples were obtained from UV-Vis DRS spectra. The luminescence spectra of Ln2/3MoO4 (Ln=Pr, Eu and Dy) showed characteristic transitions of the rare earth ions. The visible light photocatalytic activity of all the samples was studied against degradation of methylene blue.

  14. Hydrothermal synthesis and tunable luminescence of CaSiO{sub 3}:RE{sup 3+}(RE{sup 3+} = Eu{sup 3+}, Sm{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Linlin; Yang, Xingxing [State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012 (China); Fu, Zuoling, E-mail: zlfu@jlu.edu.cn [State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012 (China); Wu, Zhijian [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Jeong, Jung Hyun, E-mail: jhjeong@pknu.ac.kr [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2015-05-15

    Highlights: • Near-spherical CaSiO{sub 3} nanocrystals were synthesized via a hydrothermal method. • The effect of calcination temperature on crystalline phase formation was discussed. • Optical properties of trivalent ions doped CaSiO{sub 3} nanocrystals were investigated. • Tunable luminescence of CaSiO{sub 3}:Tb{sup 3+}, Eu{sup 3+} can be achieved by a simple method. - Abstract: CaSiO{sub 3}:RE{sup 3+} (RE{sup 3+} = Eu{sup 3+}, Sm{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) nanocrystals were prepared by facile hydrothermal method with further calcinations. The crystal structure and the effects of annealing temperature on phase transition have been characterized by X-ray diffraction (XRD). The photoluminescence (PL) and PL excitation (PLE) spectra were used to characterize the optical properties of all samples. The effect of Eu{sup 3+} and Sm{sup 3+} doping concentrations on the luminescent intensity were also investigated in details, respectively. Moreover, the luminescence colors of the Tb{sup 3+} and Eu{sup 3+} co-doped CaSiO{sub 3} samples can be tuned by simply adjusting the relative doping concentrations of the rare earth ions under a single wavelength excitation, which might find potential applications in the fields of light display systems and optoelectronic devices.

  15. Hydrothermal synthesis and luminescent properties of CaWO4: 3 + M3 + Eu , ( M = Tb, Sm, Bi, Dy)%CaWO4:Eu3+,M3+(M=Tb,Sm,Bi,Dy)的水热合成及发光性能研究

    Institute of Scientific and Technical Information of China (English)

    张丽霞; 梁利芳; 唐上惠; 易敏; 庞起

    2011-01-01

    利用水热合成法制备CaWO4∶Eu3+以及CaWO4∶Eu3+,M3+(M=Tb,Sm,Bi,Dy)系列钨酸盐基荧光粉,利用XRD表征产物CaWO4∶Eu3+(5%)的晶体结构,结果表明其结构和CaWO4的标准物相结构相似,为四方晶系结构;研究了CaWO4∶Eu3+的发光性能以及第二掺杂离子M3+(M=Tb,Sm,Bi,Dy)对荧光粉发光性能的影响,结果表明,在273 nm紫外光激发下,掺入Tb3+和Sm3+离子对CaWO4基质发光强度没有明显影响,但能增强荧光粉中Eu3+离子617 nm处的红光发射强度;掺入Bi3+和Dy3+离子能明显降低CaWO4基质的发光强度,同时能增强荧光粉中Eu3+离子617 nm处的红光发射强度.%Tungstate-based phosphors CaWO4: Eu3 + and CaWO4: Eu3 + , M3 + ( M = Tb, Sm, Bi,Dy) were prepared successfully by hydrothermal synthesis method. The crystal structure of CaWO4:Eu3+ (5%) characterized by XRD was tetragonal system, which was in accordance with CawO4 ( JCPDS file 85 - 0443 ). The luminescent properties of CaWO4: Eu3 + and the effect of M3 + ( M = Tb,Sm, Bi, Dy) on the luminescent properties of the fluorescent powder were investigated. Under the excitation of 273 nm, either Tb3 + or Sm3 + had no obvious effect on the emission intensity of CaWO4,but can enhance the intensity of 617 nm emission of Eu3+ ion. On the other hand, either Bi3 + or Dy3+ ion can reduce the emission intensity of CaWO4 and enchance the intensity of 617 nm emission of Eu3 + ion.

  16. Crystal chemistry of the orthorhombic Ln2TiO5 compounds with Ln=La, Pr, Nd, Sm, Gd, Tb and Dy

    Science.gov (United States)

    Aughterson, Robert D.; Lumpkin, Gregory R.; Thorogood, Gordon J.; Zhang, Zhaoming; Gault, Baptiste; Cairney, Julie M.

    2015-07-01

    The crystal structures of seven samples of orthorhombic (Pnma) Ln2TiO5 compounds with Ln=La, Pr, Nd, Sm, Gd, Tb and Dy were refined by Rietveld analysis of synchrotron X-ray powder diffraction (S-XRD) data. With increasing size of the lanthanide cation, the lattice parameters increase systematically: c by only ~1.5% whereas both a and b by ~6% from Dy2TiO5 to La2TiO5. The mean Ti-O bond length only increases by ~1% with increasing radius of the Ln cation from Gd to La, primarily due to expansion of the pair of Ti-O3 bonds to opposite corners of the Ti-O5 square based pyramid polyhedra. For Dy2TiO5 and Tb2TiO5, a significant variation in Ti-O1 and Ti-O4 bond lengths results in an increased deformation of the Ti-O5 base. The particular configuration consists of large rhombic shaped tunnels and smaller triangular tunnels along the b axis, which have implications for defect formation and migration caused by radiation damage or the ionic conductivity.

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

    Science.gov (United States)

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

    2009-08-01

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

  18. Electron-magnon interaction in RNiBC (R=Er, Ho, Dy, Tb, and Gd) series of compounds based on magnetoresistance measurements

    Science.gov (United States)

    Fontes, M. B.; Trochez, J. C.; Giordanengo, B.; Bud'ko, S. L.; Sanchez, D. R.; Baggio-Saitovitch, E. M.; Continentino, M. A.

    1999-09-01

    We present a study of the transport and magnetic properties of a series of RNiBC compounds (R=Er, Ho, Dy, Tb, and Gd). All the materials investigated have long range magnetic order at sufficiently low temperatures. Magnetoresistance measurements are presented for a large range of temperatures (T) and magnetic fields (H). We show that below the critical temperature, the temperature dependence of the resistivity is determined by electron scattering due to the elementary excitations (spin waves) of the ordered magnetic phase and the values of the gap in the magnon spectra were derived. Finally we discuss the H×T phase diagram of these materials.

  19. Effects of carbon on Pr0.15Tb0.30Dy0.55Fe1.85 compound

    Institute of Scientific and Technical Information of China (English)

    LIU Heyan; LI Yangxian; YU Xiao; LI Songtao; MENG Xiangxi; XU Xuewen

    2006-01-01

    The structure, Curie temperature and magnetostriction of Pr0.15Tb0.30Dy0.55Fe1.85Cx (x=0-0.1) compounds were investigated by X-ray diffraction, a vibrating sample magnetometer and a standard strain technique.All the samples show entirely MgCu2-type Laves phase structure.The lattice parameter and Curie temperature increase with C content increasing.The magnetostriction at high magnetic field shows maximum value at x=0.05.

  20. Crystallographic and magnetic properties of R sub 3 Fe sub 2 sub 9 sub - sub x V sub x N sub 4 (R=Y, Ce, Nd, Sm, Gd, Tb, and Dy)

    CERN Document Server

    Han Xiu Feng; Li Qi; Zhang Mao Cai; Zhou Shou Zeng

    1998-01-01

    A systematic investigation of crystallographic and magnetic properties of nitride R sub 3 Fe sub 2 sub 9 sub - sub x V sub x N sub 4 (R = Y, Ce, Nd, Sm, Gd, Tb, and Dy) has been performed. Nitrogenation leads to a relative volume expansion of about 6%. The lattice constants and unit cell volume decrease with increasing rare-earth atomic number from Nd to Dy, reflecting the lanthanide contraction. On average, the Curie temperature increases due to the nitrogenation to about 200 K compared with its parent compound. Generally speaking, nitrogenation also results in a remarkable improvement of the saturation magnetization and anisotropy fields at 4.2 K and room temperature for R sub 3 Fe sub 2 sub 9 sub - sub x V sub x N sub 4 compared with their parent compounds. The transition temperature indicates the spin reorientations of R sub 3 Fe sub 2 sub 9 sub - sub x V sub x N sub 4 for R Nd and Sm are at around 375 and 370 K which are higher than that of R sub 3 Fe sub 2 sub 9 sub - sub x V sub x for R = Nd and Sm 145...

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

    Directory of Open Access Journals (Sweden)

    Tony D. Kelly

    2014-05-01

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

  2. Investigation of local magnetism in RZn (R = Ce, Gd, Tb, Dy) and GdCu intermetallic compounds using perturbed angular correlation gamma-gamma spectroscopy; Investigacao do magnetismo local em compostos intermetalicos do tipo RZn (R = Ce, Gd, Tb, Dy) e GdCu pela espectroscopia de correlacao angular gama-gama perturbada

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Brianna Bosch dos

    2010-07-01

    This work presents, from a microscopic point of view, a systematic study of the local magnetism in RZn (R = Ce, Gd, Tb, Dy) and GdCu intermetallic compounds through measurements of hyperfine interactions using the Perturbed Angular Correlation Gamma- Gamma Spectroscopy technique with {sup 111}In {yields} {sup 111}Cd and {sup 140}La {yields} {sup 140}Ce as probe nuclei. As the magnetism in these compounds originates from the 4f electrons of the rare-earth elements it is interesting to observe in a systematic study of RZn compounds the behavior of the magnetic hyperfine field with the variation of the number of 4f electrons in the R element. The use of probe nuclei {sup 140}La {yields} {sup 140}Ce is interesting because Ce{sup +3} ion posses one 4f electron which may contribute to the total hyperfine field, and the results showed anomalous behavior. The results for {sup 111}Cd probe showed that the temperature dependence of the magnetic hyperfine field follows the Brillouin function, and the magnetic hyperfine field decreases linearly with increase of the atomic number of rare earth when plotted as a function of the rare-earth J spin projection, showing that the main contribution to the magnetic hyperfine field in RZn compounds comes from the polarization of the conduction electrons. The results for the electric field gradient measured with {sup 111}Cd for all compounds showed a strong decrease with the atomic number of the rare-earth element. We have therefore assumed that the major contribution to the electric field gradient originates from the 4f electrons of the rare-earths. The measurements of the electric field gradient for GdCu with {sup 111}Cd, after temperature decreases and increases again showed that two different structures, CsCl-type cubic and FeB-type orthorhombic structures co-exist. Finally, it is the first time that measurements of hyperfine parameters have been carried out with theses two probe nuclei in the studied RZn. (author)

  3. Preparation of Nanocrystalline Rare Earth Mixed Oxides DyFexCo1-xO3-δ and Its Conductivity

    Institute of Scientific and Technical Information of China (English)

    任引哲; 王建英; 刘二保

    2002-01-01

    Nanocrystalline rare earth mixed oxides DyFexCo1-xO3-δ were prepared by sol-gel method and characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG-DTA) and scanning electron microscope (SEM). The results show that DyFexCo1-xO3-δ has the structure of perovskite type at 800 ℃ for 2 h calcination. The conductivity of the materials at different temperature was measured by four-probe instrumentation and two-pole method. The results show that the conductivity of mixed oxides DyFexCo1-xO3-δ is higher than those of un-mixed oxides DyFeO3 and DyCoO3 and the conductivity is the best at x=0.8 in the matter of DyFexCo1-xO3-δ. The conductivity of these materials always increases with the temperature rising and there is an apparent change between 600 and 800 ℃. However, the spinodals are different with different ration of Fe3+ and Co3+. This kind of oxide is a conductive pottery material.

  4. Stability constants of La(III), Pr(III), Nd(III), Sm(III), Gd(III), Tb(III) and Dy(III) complexes with N-(2-hydroxyphenyl) p-toluene sulphonamide

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, S.C.; Mathur, K.C. (Jodhpur Univ. (India). Dept. of Chemistry)

    1981-01-01

    The dissociation constants of the ligand and stability constants of La(III), Pr(III), Nd(III), Sm(III), Gd(III), Tb(III) and Dy(III) complexes with N-(2-hydroxyphenyl) p-toluene sulphonamide have been determined potentiometrically using Calvin-Bjerrum pH titration technique at 30 +- 1deg C and ..mu.. = 0.1 M (NaClO/sub 4/) in aqueous medium. The stability constants of these metal complexes are found to follow the order Dy > Tb > Gd > Sm > Nd > Pr > La.

  5. Difference in the luminescence properties of orthorhombic and monoclinic forms of Y{sub 2}GeO{sub 5}:Ln (Ln = Tb{sup 3+} and Dy{sup 3+})

    Energy Technology Data Exchange (ETDEWEB)

    Tyagi, Adish; Shah, Alpa; Sudarsan, V., E-mail: vsudar@barc.gov.in; Vatsa, R.K.; Jain, V.K., E-mail: jainvk@barc.gov.in

    2015-04-15

    Highlights: • Improved emission colour purity with orthorhombic form of Y{sub 2}GeO{sub 5}. • Non-stationary quenching exists in orthorhombic and monoclinic forms of Y{sub 2}GeO{sub 5}:Tb. • Ion pair formation and cross relaxation quenching operating for Y{sub 2}GeO{sub 5}:Dy samples. - Abstract: The luminescence properties of Tb{sup 3+} and Dy{sup 3+} doped orthorhombic and monoclinic forms of Y{sub 2}GeO{sub 5} are significantly different. Orthorhombic Y{sub 2}GeO{sub 5} doped with Tb{sup 3+} and Dy{sup 3+} ions gives bright green and blue emission upon UV light excitation with CIE coordinates (0.25, 0.46) and (0.25, 0.24), respectively. The monoclinic Y{sub 2}GeO{sub 5} doped with these ions exhibits light green and yellowish white emissions, respectively. This has been attributed to the differences in crystallographic environments around Y{sup 3+} ions in orthorhombic and monoclinic forms of Y{sub 2}GeO{sub 5}. Quantum yield of emission for orthorhombic Y{sub 2}GeO{sub 5}:Tb (∼29%) is significantly higher than that of the monoclinic Y{sub 2}GeO{sub 5}:Tb (∼14%). Lifetime values corresponding to {sup 4}F{sub 9/2} level of Dy{sup 3+} ions in both monoclinic and orthorhombic forms of Y{sub 2}GeO{sub 5} follow an opposite trend with respect to {sup 5}D{sub 4} level of Tb{sup 3+} ions. This is attributed to difference in the concentration quenching mechanism operating for Tb{sup 3+} and Dy{sup 3+} ions.

  6. Morphology and luminescence characteristics of combustion synthesized Y{sub 2}O{sub 3}: (Eu, Dy, Tb) nanoparticles with various amino-acid fuels

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, S.; Sudarsan, V. [Chemistry Division Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Sastry, P.U.; Patra, A.K. [Solid State Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Tyagi, A.K., E-mail: aktyagi@barc.gov.in [Chemistry Division Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2014-01-15

    Y{sub 2}O{sub 3} nanoparticles doped with Dy{sup 3+}, Eu{sup 3+} and Tb{sup 3+} together were prepared by the gel combustion method using a variety of amino acids namely, glycine, phenyl alanine, arginine, glutamic and aspartic acids. Number of carboxylate groups present in the amino acids used for combustion reaction was found to have strong influence on powder characteristics as well as luminescence from the samples. Based on small angle X-ray scattering studies, it is inferred that the nanoparticles prepared by using glycine and arginine as the fuels have smooth surface compared to those prepared using other amino acids. For the nanoparticles prepared using glutamic and aspartic acids, there exist a diffused pore-grain interface due to the lesser extent of heat generated in the reaction which leads to smaller particle size, poor crystallinity and improper burning of the organic materials. Lower surface area and smooth surface of the nanoparticles prepared using glycine leads to their improved luminescence properties. -- Highlights: • Surface smoothness of Y{sub 2}O{sub 3} (Dy, Eu, Tb) nanoparticles vary with amino acids. • Optimum luminescence intensity is observed when glycine is used as the fuel. • Diffused pore grain interface when glutamic and aspartic acids are used as fuels.

  7. Magnetic and electrical properties of the stannides RE sub 3 Co sub 6 Sn sub 5 (RE Sm, Gd, Tb and Dy)

    CERN Document Server

    Kaczorowski, D; Rogl, P; Romaka, L; Gorelenko, Y

    2003-01-01

    Polycrystalline samples of the ternary intermetallics RE sub 3 Co sub 6 Sn sub 5 (RE Sm, Gd, Tb and Dy) were studied by means of magnetization, dc magnetic susceptibility and electrical resistivity measurements. All these stannides were found to order magnetically at low temperatures. Sm sub 3 Co sub 6 Sn sub 5 is antiferromagnetic below T sub N = 8 K, while Tb sub 3 Co sub 6 Sn sub 5 exhibits ferromagnetic ordering below T sub C = 16 K. The other two compounds show more complex magnetic behaviour with subsequent phase transitions in the ordered regions. For Gd sub 3 Co sub 6 Sn sub 5 one observes the onset of ferromagnetism at T sub C = 25 K, which is followed by a change in the magnetic structure at T sub 1 = 12 K. In the case of Dy sub 3 Co sub 6 Sn sub 5 an antiferromagnetic type of order sets in at T sub N = 7 K, and then a spin structure rearrangement occurs at T sub 1 = 3 K that yields a ferromagnetic component at lower temperatures. All the ternaries studied exhibit metallic-like conductivity with pro...

  8. Enhanced Magnetostriction of a Narrow Hysteresis Tb0.26Dy0.54Ho0.20Fe2 Alloy

    Institute of Scientific and Technical Information of China (English)

    Xingwen PAN; Changsheng ZHANG; Tianyu MA; Mi YAN; Jing LI

    2013-01-01

    In this work,a magnetic annealing method used to enhance the magnetostrictive property of a narrow hysteresis alloy Tb0.26Dy0.54Ho0.20Fe2 is reported.Cylindrical-rod shaped specimen with crystal orientation was fabricated using zone-melting unidirectional solidification technique,followed by annealing in a transverse magnetic field of 366 kA/m.The crystal orientation and bi-phase solidified morphology can be retained after magnetic annealing.A high magnetostriction of 1.508×10-3 was obtained in the magnetically annealed specimen,which is 25.2% larger than the untreated one.Simultaneously,the magnetostriction hysteresis width is slightly enlarged from 4.45 to 6.36 kA/m,which is still much lower than that of the Ho-free Tb0.3Dy0.7Fe2 alloy.The additional anisotropy which is induced by magnetic annealing,as reflected by the magnetic hysteresis loops,is responsible for the enhancement of magnetostrictive performance.

  9. Crystal chemistry of the orthorhombic Ln{sub 2}TiO{sub 5} compounds with Ln=La, Pr, Nd, Sm, Gd, Tb and Dy

    Energy Technology Data Exchange (ETDEWEB)

    Aughterson, Robert D., E-mail: roa@ansto.gov.au [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, Lucas Heights 2234, NSW (Australia); Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney 2006, NSW (Australia); Lumpkin, Gregory R., E-mail: grl@ansto.gov.au [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, Lucas Heights 2234, NSW (Australia); Thorogood, Gordon J., E-mail: gjt@ansto.gov.au [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, Lucas Heights 2234, NSW (Australia); Zhang, Zhaoming [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, Lucas Heights 2234, NSW (Australia); Gault, Baptiste, E-mail: baptiste.gault@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Cairney, Julie M., E-mail: julie.cairney@sydney.edu.au [Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney 2006, NSW (Australia)

    2015-07-15

    The crystal structures of seven samples of orthorhombic (Pnma) Ln{sub 2}TiO{sub 5} compounds with Ln=La, Pr, Nd, Sm, Gd, Tb and Dy were refined by Rietveld analysis of synchrotron X-ray powder diffraction (S-XRD) data. With increasing size of the lanthanide cation, the lattice parameters increase systematically: c by only ~1.5% whereas both a and b by ~6% from Dy{sub 2}TiO{sub 5} to La{sub 2}TiO{sub 5}. The mean Ti–O bond length only increases by ~1% with increasing radius of the Ln cation from Gd to La, primarily due to expansion of the pair of Ti–O{sub 3} bonds to opposite corners of the Ti–O{sub 5} square based pyramid polyhedra. For Dy{sub 2}TiO{sub 5} and Tb{sub 2}TiO{sub 5}, a significant variation in Ti–O{sub 1} and Ti–O{sub 4} bond lengths results in an increased deformation of the Ti–O{sub 5} base. The particular configuration consists of large rhombic shaped tunnels and smaller triangular tunnels along the b axis, which have implications for defect formation and migration caused by radiation damage or the ionic conductivity. - Graphical abstract: Figure: The crystallographic study of a systematic series of compounds with nominal stoichiometry Ln{sub 2}TiO{sub 5} (with Ln representing La, Pr, Nd, Sm, Gd, Tb and Dy) and orthorhombic, Pnma, symmetry shows changes in cell parameters which fit a linear trend. However, bond lengths are shown to deviate from trend with compounds containing the smaller, heavier lanthanides. - Highlights: • First fabrication and crystallographic refinement of compound Pr{sub 2}TiO{sub 5}. • First systematic study of the crystallography, using S-XRD, for Ln{sub 2}TiO{sub 5} series. • Cation to anion bonding trends and valence states are investigated. • The densities and band-gaps of the series are experimentally determined.

  10. Interplay of antiferromagnetic and antiferroquadrupolar interactions in DyAg and other rare earth intermetallic compounds

    Science.gov (United States)

    Morin, P.; Rouchy, J.; Yonenobu, K.; Yamagishi, A.; Date, M.

    1989-10-01

    The study of the magnetoelasticity of the cubic (CsCl-type) rare earth intermetallic DyAg allows us to determine the strength of both the magnetoelastic coupling and the quadrupolar pair interactions. These latter ones are observed to be negative (antiferroquadrupolar type) for the tetragonal symmetry as well as for the trigonal one. They drive the magnetic structure to be triple- q at low temperature: the cubic magnetic cell consists of four pairs of ferromagnetic moments pointing along each of the treefold axes. At high temperature, it is replaced by a double- q structure, then, immediately below TN, by a modulated arrangement. The magnetization processes have been thoroughly studied along the three main axes in fields up to 40 T and compared with previous results in isomorphous DyCu and in the AuCu 3-type compound TmGa 3. The sequences under field of the different magnetic structures are identical and mainly determined by the crytalline electric field and the antiferroquadrupolar interactions. These 3 compounds do not set a peculiar case, but seem to belong to a larger family of cubic compounds with multiaxial structures governed by antiferroquadrupolar terms.

  11. Luminescence characteristic of RE (RE = Pr, Sm, Eu, Tb, Dy) and energy levels of lanthanide ions in Gd5Si3O12N

    Science.gov (United States)

    Zhang, Zhi-Jun; Yang, Woochul

    2017-10-01

    Polycrystalline Gd5Si3O12N: RE (RE = Pr, Sm, Eu, Tb and Dy) phosphors have been synthesized via a solid-state reaction method at high temperature, and their photoluminescence properties were studied. The absorption peak at about 230 nm is attributed to the host absorption. For the Pr3+-doped sample, the typical excitation lines located at 273 nm originating from the 8S7/2 → 6IJ (J = 5/2, 7/2) transitions of the Gd3+ ions were observed in the excitation spectra. Upon excitation at 227 nm UV light, the 4f15d → 4f2 emission band (350-450 nm) and typical 4f2 → 4f2 emission lines (450-700 nm) assigned to Pr3+ were observed. The Sm3+-doped sample exhibits a bright red emission owing to the 4G5/2 → 6HJ (J = 5/2, 7/2 and 9/2) transitions. However, the charge transfer band of Sm3+ was not observed in the excitation spectrum. There is a broad band from 200 to 350 nm originating from the charge transfer transition (CT) of the Eu3+ (O2-/N3- → Eu3+) in the excitation spectra, and the strongest peak in the emission spectra located at 615 nm is due to the electric-dipole 5D0 → 7F2 transition of Eu3+. For the Tb3+-doped sample, it shows 5D3 →7FJ (J = 5, 4, 3, 2) blue line emissions and 5D4 → 7FJ (J = 6, 5, 4, 3) green line emissions under the excitation of Tb3+. The Dy3+-activated sample upon excitation at 349 and 386 nm UV light shows blue-green and orange-red emission lines originating from 4F9/2 → 6HJ (J = 15/2, 13/2) transitions. In addition, the energy transfer from the host lattice to the luminescence activators (i.e. Pr3+, Sm3+, Eu3+, Tb3+, Dy3+) has been confirmed. In addition, the energy level diagram including the 4f and 5d energy levels of all Ln2+ and Ln3+ ions relative to the valence and conduction band of Gd5Si3O12N were constructed and discussed.

  12. Study of hyperfine interactions in intermetallic compounds Gd(Ni,Pd,Cu)In, Tb(Ni,Pd)In, Dy(Ni,Pd)In and Ho(Ni,Pd)In; Estudo de interacoes hiperfinas em compostos intermetalicos Gd(Ni,Pd,Cu)In, Tb(Ni,Pd)In, Dy(Ni,Pd)In e Ho(Ni,Pd)In

    Energy Technology Data Exchange (ETDEWEB)

    Lapolli, Andre Luis

    2006-07-01

    Systematic behavior of magnetic hyperfine field (B{sub hf}) in the intermetallic compounds Gd(Ni,Pd,Cu)In Tb(Ni,Pd)In, Dy(Ni,Pd)In and Ho(Ni,Pd)In was studied by Perturbed Gamma-Gamma Angular Correlation spectroscopy. The measurements of B{sub hf} were carried out at the rare earth atom and in sites using the nuclear probes {sup 140}Ce and {sup 11}'1Cd respectively. The variation of hyperfine field with temperature, in most cases, follows the Brillouin function predicted from the molecular field theory. The hyperfine field values at rare earth atom sites obtained from {sup 140}Ce probe as well as at in sites obtained from {sup 111}Cd probe for each series of compounds were extrapolated to zero Kelvin B{sub hf}(T=0) from these curves. These values were compared with the values of the literature for other compounds containing the same rare earth element and all of them show a linear relationship with the ordering temperature. This indicates that the main contribution to B{sub hf} comes from the conduction electron polarization (CEP) through Fermi contact interaction and the principal mechanism of magnetic interaction in these compounds can be described by the RKKY type interaction. The values of B{sub hf}(T=0) for each family of intermetallic compounds RNiIn and RPdIn when plotted as a function of 4f spin projection of rare earth element also shows a linear relationship. Exceptions are the results for the compounds RNiIn obtained with {sup 111}Cd probe where a small deviation from linearity is observed. The results of the measurements carried out with the {sup 111}Cd probe were also analyzed to obtain the hyperfine parameters of the quadrupole interaction as a function of temperature for RPdln and GdNiIn compounds. The results show that for the compound GdPdIn there might be some Gd-In disorder at high temperature. (author)

  13. Ca3(PO4)2∶RE3+(RE=Eu,Dy,Ce,Tb)荧光粉的制备及其发光特性%Preparation and luminescence properties of Ca3(PO4)2∶RE3+(RE=Eu,Dy, Ce,Tb) phosphors

    Institute of Scientific and Technical Information of China (English)

    孟涛; 胡正发; 张伟; 王雄庭; 叶定华; 王银海; 罗莉; 王伟; 杜姬芳

    2013-01-01

    采用高温固相法合成了Ca3 (PO4)2∶RE3+ (RE=Eu,Dy,Ce,Tb)系列发光材料,研究了其发光性质.研究表明Ca3(PO4)2∶ RE3+在紫外区域均能有效被激发,有很强的荧光发射,且发光范围覆盖蓝到红光波段,是一类可以紫外激发实现白光LED用的潜在荧光粉.在0.005~0.03 mol浓度范围内,Eu,Dy和Ce掺杂的荧光粉的发光都发生了浓度淬灭,分别对应于0.025 mol,0.025 mol和0.02 mol,而Tb3+掺杂样品表现出高的发光淬灭浓度.%A series of phosphors Ca3(1-x)(PO4)2∶ xRE3+(RE=Eu,Dy,Ce,Tb) were prepared by a high temperature solid-state reaction method.Their luminescence properties were investigated.The results indicated that all samples can be effectively excited by ultraviolet light with fluerescence range from blue to red light,and they are the potential phosphors to obtain white LED excited by ultraviolet light.In the range of 0.005 ~ 0.03 mol,photoluminescence quenching concentration of Eu3+,Dy3+,and Ce3+-doped are 0.025 mol,0.025 mol and 0.02 mol,respectively,and Tb3+-doped samples has high quenching concentration.

  14. Influence of Rare Earth Elements on Luminescent Properties of Y2SiO5:Tb

    Institute of Scientific and Technical Information of China (English)

    Jiao Huan; Liao Fuhui; Zhou Jingjing; Jing Xiping

    2005-01-01

    Photoluminescent(PL) and cathodoluminescent(CL) properties of rare earths (Sc3+, La3+, Gd3+ and Lu3+) doped (Y0.97Tb0.03)2SiO5 were studied. Rare earth doping clearly influences PL and CL properties of Y2SiO5:Tb. For La3+ doped system, PL intensity increases nearly 10% at x=0.05 whereas for Lu3+ doped system, the intensity increases about 20% at x=0.20. Gd3+ doping and Sc3+ doping reduce the intensity; at x=0.3, it is reduced about 30% for Gd3+ doped system and about 15% for Sc3+ doped system, respectively. Quenching concentration of activator became higher in rare earth doped samples, which may be understood by that the rare earth dopants might dilute the concentration of the activator. Additionally, doping also influences the color saturation of Y2SiO5:Tb. Sc3+, La3+, and Gd3+ doping improve the color saturation, whereas Lu3+ doping decreases the color saturation. CL measurements show that CL intensity increases for all rare earths doped systems. The energy transfer from Gd3+ to Tb3+ was discussed.

  15. Synthesis and photoluminescence characteristics of (Y,Gd)BO3:RE (RE = Eu(3+), Ce(3+), Dy(3+) and Tb(3+)) phosphors for blue chip and near-UV white LEDs.

    Science.gov (United States)

    Rangari, V V; Singh, V; Dhoble, S J

    2016-03-01

    A series of Eu(3+)-, Ce(3+)-, Dy(3+)- and Tb(3+)-doped (Y,Gd)BO3 phosphors was synthesized by a solid-state diffusion method. X-Ray diffraction confirmed their hexagonal structure and the scanning electron microscopy results showed crystalline particles. The excitation spectra revealed that (Y,Gd)BO3 phosphors doped with Eu(3+), Ce(3+), Dy(3+) and Tb(3+) are effectively excited with near UV-light of 395 nm/blue light, 364, 351 and 314 nm, respectively. Photoluminescence spectra of Eu(3+)-, Ce(3+)- and Tb(3+)/Dy(3+)-doped phosphor showed intense emission of reddish orange, blue and white light, respectively. The phosphor Y0.60Gd0.38BO3:Ce0.02 showed CIE 1931 color coordinates of (0.158, 0.031) and better color purity compared with commercially available blue BAM:Eu(2+) phosphor. The phosphor (Y,Gd)BO3 doped with Eu(3+), Dy(3+) and Tb(3+) showed CIE 1931 color coordinates of (0.667, 0.332), (0.251, 0.299) and (0.333, 0.391) respectively. Significant photoluminescence characteristics of the prepared phosphors indicate that they might serve as potential candidates for blue chip and near-UV white light-emitting diode applications. Copyright © 2015 John Wiley & Sons, Ltd.

  16. Phase diagram of the Fe-rich portion of R-Fe-Al pseudoternary system(R=Dy0.65Tb0.25Pr0.1)

    Institute of Scientific and Technical Information of China (English)

    王博文; 吴昌衡; 庄育智; 金希梅

    1996-01-01

    The 1000℃ isothermal section of the Fe-rich portion of R-Fe-Al(R=Dy0.65Tb0.25Pr0.1) pseudoternary system has been investigated using optical microscopy,X-ray diffraction,EPMA and DTA techniques.The 1000℃ isothermal section consists of 9 single-phase regions,14 two-phase regions and 6 three-phase regions.In the R-Fe pseudobinary system,except the R2Fe17 compound,the homogeneity regions of other compounds are shifted towards the stoichiometric rare earth-rich side.With Fe partially substituted by Al,the homogeneity region of R(Fe1-xAlx)2 is shifted back to the stoichiometric composition when x=0.15 and remains little changed with 0.15≤x≤0.30.The homogeneity regions of R(Fe1-xAlx)3 and R6(Fe1-xAlx)23 are slightly shifted to the stoichiometric rare earth-rich side with increasing Al content.A vertical section along R=33.33 atomic percentage is also investigated.It consists of 2 single-phase regions,4 two-phase regions and 2 three-phase regions.

  17. Structural, magnetic and electronic transport studies of RAgSn2 compounds (R = Y, Tb, Dy, Ho and Er) with Cu3Au-type

    Indian Academy of Sciences (India)

    L Romaka; V V Romaka; I Lototska; A Szytula; B Kuzhel; A Zarzycki; E K Hlil; D Fruchart

    2013-12-01

    RAgSn2 compounds, where R = Y, Tb, Dy, Ho and Er, were synthesized by arc-melting and subsequent annealing at 870 K. The formation of cubic phases with Cu3Au-type structure (space group $\\bar{3}$) was studied. Magnetic property measurements showed that in paramagnetic state, the compounds with magnetic rareearth atoms are Curie–Weiss paramagnets and order antiferromagnetically at low temperatures. YAgSn2 is a Pauli paramagnet in 100–300 K temperature range. The electrical properties of RAgSn2 compounds were investigated by means of electrical resistivity and Seebeck coefficient measurements in 4.2–300 K temperature range. All investigated compounds exhibit metallic type of conductivity. Electronic structure calculations based on full potential linearized augmented plane wave (FLAPW)method is also carried out to probe themagnetic and electronic structures of RAgSn2 compounds. Comparisons between experimental data and calculations are discussed.

  18. Effects of Magnetic Heat Treatment on Magnetostiction Properties of Tb0.3 Dy0.7 Fe1.95 Alloy

    Institute of Scientific and Technical Information of China (English)

    Jiang Liping; Zhao Zengqi; Wu Shuangxia; Qiu Jufeng; Sha Yuhui; Zuo Liang

    2004-01-01

    The effects of magnetic heat treatment on magnetostriction properties of Tb0.3Dy0.7Fe1.95 alloy were investigated.The directionally solidified alloy was heated to various temperatures near Curie temperature TC in vacuum, kept for a certain time under the application of magnetic field and then cooled to room temperature.The magnetostriction coefficient was measured by a resistance strain gage.The crystal structure was analyzed by X-ray diffraction (XRD).The experimental results show that the magnetostriction coefficient obviously increases and the grains orientations along the axis changed somewhat as the field of 1 T vertical to axis of the rod-shaped specimen is applied for 5 min at the heating temperature slightly lower than TC.

  19. Pico- and subpicosecond relaxation processes in lanthanide-porphyrin complexes. [Lanthanoids: Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu

    Energy Technology Data Exchange (ETDEWEB)

    Solov' ev, K.N.; Tsvirko, M.P.; Krasauskas, V.V.; Pyatosin, V.E.; Stel' makh, G.F.

    1984-03-01

    Methods of nano- and picosecond absorption spectroscopy and luminescence are used to determine the deactivation rates of ..pi.., ..pi..*-electron states of S/sub 2/, S/sub 1/ and T/sub 1/ in complexes of organic molecules of meso-tetratolylporphyne and tetrabenzoporphyne with trivalent Sm/sup 3 +/, Eu/sup 3 +/, Gd/sup 3 +/, Tb/sup 3 +/, Dy/sup 3 +/, Ho/sup 3 +/, Er/sup 3 +/, Tm/sup 3 +/, Yb/sup 3 +/, Lu/sup 3 +/. Quantitative data on superfast relaxation processes in lanthanide porphyrines are obtained. The function of the metal entral ion is presented in details as the excitation factor in deactivation processes of photoexcitation energy of the systems in question.

  20. New Materials Derived from Ybco: CrSr2RECu2O8 (RE = La, Pr, Nd, Eu, Gd, Tb, Dy, Y, Ho, Er, Lu).

    Science.gov (United States)

    Ruiz-Bustos, Rocío; Aguirre, Myriam H; Alario-Franco, Miguel A

    2005-05-02

    Eleven new oxides, derived from yttrium barium copper oxide by replacing the square-planar copper [Cu-O4] of the basal plane of the triple perovskite-based structure with octahedral Cr(IV), have been prepared at high pressure and temperature. Their crystal structures have been determined, and their complex microstructure has been established by means of high-resolution electron microscopy and electron diffraction. The materials have a general formula of CrSr2RECu2O8 (RE = La, Pr, Nd, Eu, Gd, Tb, Dy, Y, Ho, Er, and Lu); they are tetragonal, show the symmetry of space group P4/mmm, and do not appear to be superconducting.

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

    Science.gov (United States)

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

    2014-11-17

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

  2. Emission of Rare Earth Complex Tb0.5Eu0.5(asprin)3phen

    Institute of Scientific and Technical Information of China (English)

    沈鸿; 徐征; 陶栋梁; 徐怡庄; 章婷; 杨军

    2003-01-01

    The coprecipitate Tb0.5Eu0.5(asprin)3phen was synthesized. By doping the rare earth complex into polymer PVK, the EL device was fabricated with the structure of ITO/PVK∶RE/PBD/Al. Compared with the device using PVK/Eu(asprin)3phen blend as the light emitting layer, the emission of Eu3+ in the PVK/Tb0.5Eu0.5(asprin)3 phen blend is greatly enhanced along with the quenching of the emission of PVK.

  3. Luminescence and Valence of Tb Ions in Alkaline Earth Stannates and Zirconates Examined by X-ray Absorption Fine Structures.

    Science.gov (United States)

    Ueda, Kazushige; Shimizu, Yuhei; Nagamizu, Kouta; Matsuo, Masashi; Honma, Tetsuo

    2017-10-03

    The difference in Tb(3+) green luminescence intensities in doped perovskite(ABO3)-type alkaline earth stannates, AeSnO3 (Ae = Ca, Sr, Ba), and the Mg codoping effect on the luminescence intensities in doped CaMO3 (M = Sn, Zr) were investigated utilizing the X-ray absorption fine structures (XAFS) of the Tb LIII absorption edge. It is considered that the local symmetry at A sites is responsible for the different Tb(3+) luminescence intensities in AeSnO3 (Ae = Ca, Sr, Ba) doped with Tb ions at A sites. However, it was found from the XAFS spectra that some Tb ions are unintentionally stabilized at B sites as Tb(4+), especially in BaSnO3. Not only the central symmetry for Tb(3+) at A sites but also the presence of Tb(4+) at B sites were considered to bring about the absence of Tb(3+) luminescence in doped cubic BaSnO3. No obvious changes in the Tb(3+) local structure at A sites were detected between Tb single doped and Tb-Mg codoped CaMO3 (M = Sn, Zr) from the extended XAFS oscillation, but the trace of Tb(4+) at B sites in the Tb single doped sample was observed in the X-ray absorption near edge structures. It is, therefore, considered that the Tb(3+) luminescence enhancement by Mg codoping is primarily attributed to the charge compensation rather than the changes in the local structure around Tb(3+) at A sites.

  4. Crystal Fields in Dilute Rare-Earth Metals Obtained from Magnetization Measurements on Dilute Rare-Earth Alloys

    DEFF Research Database (Denmark)

    Touborg, P.; Høg, J.

    1974-01-01

    Crystal field parameters of Tb, Dy, and Er in Sc, Y, and Lu are summarized. These parameters are obtained from magnetization measurements on dilute single crystals, and successfully checked by a number of different methods. The crystal field parameters vary unpredictably with the rare-earth solute....... B40, B60, and B66 are similar in Y and Lu. Crystal field parameters for the pure metals Tb, Dy, and Er are estimated from the crystal fields in Y and Lu....

  5. Electrical resistivity and Moessbauer effect investigations on Tb{sub 0.27}Dy{sub 0.73}(Mn{sub 1-x}Fe{sub x}){sub 2} intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Bodnar, W. [Faculty of Physics and Applied Computer Science, AGH, Al. Mickiewicza 30, 30-059 Krakow (Poland); Stoch, P. [Institute of Atomic Energy, 05-400 Swierk-Otwock (Poland); Faculty of Materials Science and Ceramics, AGH, Al. Mickiewicza 30, 30-059 Krakow (Poland); Chmist, J. [Faculty of Physics and Applied Computer Science, AGH, Al. Mickiewicza 30, 30-059 Krakow (Poland); Pszczola, J., E-mail: pszczola@agh.edu.p [Faculty of Physics and Applied Computer Science, AGH, Al. Mickiewicza 30, 30-059 Krakow (Poland); Zachariasz, P.; Suwalski, J. [Institute of Atomic Energy, 05-400 Swierk-Otwock (Poland)

    2010-09-03

    This paper concerns synthesis, X-ray analysis (300 K), electrical resistivity and {sup 57}Fe Moessbauer effect studies (4.2 K) of complete Tb{sub 0.27}Dy{sub 0.73}(Mn{sub 1-x}Fe{sub x}){sub 2} intermetallic series, with a borderline compound Tb{sub 0.27}Dy{sub 0.73}Fe{sub 2} known as Terfenol-D. A cubic Laves phase Fd3m of the MgCu{sub 2}-type is observed across the series. The lattice parameter decreases parabolically with x. Electrical resistivity was measured in a wide temperature region across the Tb{sub 0.27}Dy{sub 0.73}(Mn{sub 1-x}Fe{sub x}){sub 2} series and the parameters which characterize resistivity dependence on temperature, including Debye temperature, were determined. Residual, phonon and magnetic contributions were separated from electrical resistivity. The magnetic contribution to electrical resistivity was applied to estimate Curie temperatures. The Curie temperature increases significantly with x. {sup 57}Fe Moessbauer effect measurements for the Tb{sub 0.27}Dy{sub 0.73}(Mn{sub 1-x}Fe{sub x}){sub 2} intermetallic system evidence an [1 0 0] easy axis of magnetization. Mn/Fe substitution introduces a local area, at sub-nanoscale, with different Mn/Fe neighbourhoods of the tested {sup 57}Fe atoms. Hyperfine interaction parameters, an isomer shift, a magnetic hyperfine field and a quadrupole interaction parameter were determined from the spectra both for the local neighbourhood area and, as averaged values, for the sample as bulk. The average magnetic hyperfine field increases parabolically with x. The correlation between Curie temperatures and magnetic hyperfine fields is discussed.

  6. Precipitation based synthesis and luminescence of Ln{sup 3+} (Eu, Ce, Dy, Sm, Tb) activated BaCa{sub 2}Si{sub 3}O{sub 9}-Walstromite cyclosilicate phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Raut, S.K. [Department of Physics, R.T.M. Nagpur University, Nagpur 440033 (India); Dhoble, N.S. [Department of Chemistry, Sevadal Mahila Mahavidyalaya, Nagpur 440009 (India); Park, K. [Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 143-747 (Korea, Republic of); Dhoble, S.J., E-mail: sjdhoble@rediffmail.com [Department of Physics, R.T.M. Nagpur University, Nagpur 440033 (India)

    2014-10-15

    A series of new phosphors of BaCa{sub 2}Si{sub 3}O{sub 9}:Ln{sup 3+}, (Ln = Eu, Ce, Dy, Sm, Tb) were synthesized by precipitation based method. Good crystallinity was achieved after annealing the sample at 750 °C for 1 h in air. X-ray powder diffraction (XRD) result confirmed the formation of desired BaCa{sub 2}Si{sub 3}O{sub 9} host. The photoluminescent excitation and emission properties of Ln{sup 3+}, (Ln = Eu, Ce, Dy, Sm, Tb) activated BaCa{sub 2}Si{sub 3}O{sub 9} were investigated in detail. The photoluminescence (PL) analysis of individual Ln{sup 3+}, (Ln = Eu, Ce, Dy, Sm, Tb) activated BaCa{sub 2}Si{sub 3}O{sub 9} phosphors exhibits interesting characteristic emission properties in their respective regions. From the measured emission spectra, Judd–Ofelt (J–O) intensity parameters (Ω{sub 2}, Ω{sub 4}, Ω{sub 6}) have been calculated and using these J–O parameters various radiative parameters such as radiative transition probabilities (A{sub rad}), radiative lifetimes (τ{sub R}), branching ratios (β{sub R}) and relative quantum yield have been calculated for the studied ions. - Highlights: • A new series of phosphors BaCa{sub 2}Si{sub 3}O{sub 9}:Ln{sup 3+}, (Ln = Eu, Ce, Dy, Sm, Tb) were synthesized by precipitation method. • PL analysis of Ln{sup 3+} activated BaCa{sub 2}Si{sub 3}O{sub 9} phosphors exhibited characteristic emission properties. • By adopting J–O analysis, radiative parameters such as (A{sub rad}), (τ{sub R}), (β{sub R}) and relative quantum yield have been calculated.

  7. A structural, magnetostrictive and M(o)ssbauer study of Tb0.3Dy0.7(Fe0.9T0.1)1.95 alloys

    Institute of Scientific and Technical Information of China (English)

    ZHENG Xiaoping; ZHANG Peifeng; FAN Duowang; LI Fashen; HAO Yuan

    2005-01-01

    The effect of ⅢA metal and transition metal T substitution for Fe on crystal structure, magnetostriction and spontaneous magnetostriction, anisotropy and spin reorientation of a series of polycrystalline Tb0.3Dy0.7(Fe0.9T0.1)1.95 (T = Mn, Fe, Co, B, Al, Ga) alloys at room temperature were investigated systematically. It was found that the primary phase of the Tb0.3Dy0.7(Fe0.9T0.1)1.95 alloys is the MgCu2-type cubic Laves phase structure for different substitution. The magnetostriction λs decrases greatly for the substitution of IIIA metal B, Al and Ga, but is saturated more easily for Al and Ga substitution, showing that the Al and Ga substitution is beneficial to a decrease in the magnetocrystalline anisotropy of Tb0.3Dy0.7(Fe0.9T0.1)1.95 alloys. However, the substitution of transition metal Mn and Co decreases slightly the magnetostriction λs. It was also found that the effect of different substitutions on the spontaneous magnetostriction λ111 is distinct. The analysis of the Mossbauer spectra indicates that the easy magnetization direction in the {110} plane deviates slightly from the main axis of symmetry for Al and Ga substitution, namely spin reorientation, but it does not change evidently for B, Mn and Co substitution.

  8. Strong broad green UV-excited photoluminescence in rare earth (RE = Ce, Eu, Dy, Er, Yb) doped barium zirconate

    Energy Technology Data Exchange (ETDEWEB)

    Borja-Urby, R. [Grupo de Espectroscopia de Materiales Avanzados y Nanoestructurados (EMANA), Centro de Investigaciones en Optica A. C., Leon, Gto. 37150 (Mexico); Diaz-Torres, L.A., E-mail: ditlacio@cio.mx [Grupo de Espectroscopia de Materiales Avanzados y Nanoestructurados (EMANA), Centro de Investigaciones en Optica A. C., Leon, Gto. 37150 (Mexico); Salas, P. [Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, A.P. 1-1010, Queretaro, Qro. 76000 (Mexico); Angeles-Chavez, C. [Instituto Mexicano del Petroleo, Ciudad de Mexico, D. F. 07730 (Mexico); Meza, O. [Grupo de Espectroscopia de Materiales Avanzados y Nanoestructurados (EMANA), Centro de Investigaciones en Optica A. C., Leon, Gto. 37150 (Mexico)

    2011-10-25

    Highlights: > Trivalent rare earth (RE) substitution on Zr{sup 4+} sites in BaZrO{sub 3} lead to band gap narrowing. > RE substitution lead to enhanced blue-green intrinsic emission of nanocrystalline BaZrO{sub 3} > Blue-green hue of BaZrO3:RE depends on RE dopant and excitation UV wavelength > BaZrO3: Dy{sup 3+} PL chromatic coordinates correspond to pure white color coordinates of CIE 1931 model - Abstract: The wet synthesis hydrothermal method at 100 deg. C was used to elaborate barium zirconate (BaZrO{sub 3}) unpurified with 0.5 mol% of different rare earth ions (RE = Yb, Er, Dy, Eu, Ce). Morphological, structural and UV-photoluminescence properties depend on the substituted rare earth ionic radii. While the crystalline structure of RE doped BaZrO{sub 3} remains as a cubic perovskite for all substituted RE ions, its band gap changes between 4.65 and 4.93 eV. Under 267 nm excitation the intrinsic green photoluminescence of the as synthesized BaZrO{sub 3}: RE samples is considerably improved by the substitution on RE ions. For 1000 deg. C annealed samples, under 267 nm, the photoluminescence is dominated by the intrinsic BZO emission. It is interesting to notice that Dy{sup 3+}, Er{sup 3+} and Yb{sup 3+} doped samples present whitish emissions that might be useful for white light generation under 267 nm excitation. CIE color coordinates are reported for all samples.

  9. The interplay between magnetism and superconductivity in RNi 2B 2C (R dbnd Lu, Tm, Er, Ho, Dy, Tb, Gd)

    Science.gov (United States)

    El Massalami, M.; Bud'ko, S. L.; Giordanengo, B.; Baggio-Saitovitch, E. M.

    1995-02-01

    The superconducting and magnetic phase diagram (characteristic temperatures versus effective ionic radii) of the RNi 2B 2C (R dbnd Lu, Tm, Er, Ho, Dy, Tb, Gd) compounds are considered. Although the gradual degradation of superconductivity can be scaled to the de Gennes factor, ( g-1) 2J( J + 1), the unique reentrant behavior of the HoNi 2B 2C compound and the abrupt quenching of superconductivity for R lighter than Ho are most probably unaccountable within this scheme. Rather, it is argued that their low- T magnetic and transport properties as well as the main features of the interplay between magnetism and superconductivity can be accounted for if the low- T magnetism of HoNi 2B 2C, as reported by Grigereit et al., is generalized to the other isomorphous R members. Thus the onset of the 4f moments antiferromagnetic state at T1 is accompanied by an oscillatory component, which transforms to a commensurate antiferromagnetic state at T2. For HoNi 2B 2C, the pressure and magnetic-field influence on Tc, T1 and T2 will be discussed.

  10. Corrosion resistance and magnetostrictive properties of (Tb0.3Dy0.7)Fe2 alloy modified by nitrogen ion implantation

    Institute of Scientific and Technical Information of China (English)

    杨红川; 张世荣; 于敦波; 李扩社; 胡权霞; 杨远飞; 张坤; 李红卫

    2015-01-01

    The corrosion resistance and magnetostriction of (Tb0.3Dy0.7)Fe2 alloy were investigated for different nitrogen doses of 5×1015, 5×1016, 5×1017, 1×1018 ions/cm2 and average ion energy of 140 kV. The phase and elements concentration in the implanted layer were examined by X-ray diffraction and auger electron spectroscopy, respectively.The aqueous corrosion studies were carried out in 3.5% NaCl solutions. It was found that corrosion resistance had improved substantially with respect to the untreated substrates.The corrosion resistance was maximum at a dose of 5×1017 ions/cm2, and saturation in corrosion improvement was noticed at a higher dose, 10×1017 ions/cm2.In contrast, the results of magnetostriction tests before and after ion implantation showed that the influence of ni-trogen ion implantation on the magnetostrictive properties turned out to be small. Finally, a model was applied to interpret the influ-ence of nitrogen implantation on the magnetostriction in the light of the information provided by the experimental results in this study.

  11. Local rhombohedral symmetry in Tb{sub 0.3}Dy{sub 0.7}Fe{sub 2} near the morphotropic phase boundary

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Tianyu, E-mail: maty@zju.edu.cn [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Key Laboratory of Novel Materials for Information Technology of Zhejiang Province, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou 310027 (China); Ferroic Physics Group, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047, Ibaraki (Japan); Liu, Xiaolian; Pan, Xingwen; Li, Xiang; Jiang, Yinzhu; Yan, Mi, E-mail: mse-yanmi@zju.edu.cn [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Key Laboratory of Novel Materials for Information Technology of Zhejiang Province, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou 310027 (China); Li, Huiying; Fang, Minxia [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, Xi' an Jiaotong University, Xi' an 710049 (China); Ren, Xiaobing, E-mail: ren.xiaobing@nims.go.jp [Ferroic Physics Group, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047, Ibaraki (Japan); Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, Xi' an Jiaotong University, Xi' an 710049 (China)

    2014-11-10

    The recently reported morphotropic phase boundary (MPB) in a number of giant magnetostrictive materials (GMMs) has drawn considerable interest to the local symmetry/structure near MPB region of these materials. In this letter, by in-situ X-ray diffraction and AC magnetic susceptibility measurements, we show that Tb{sub 0.3}Dy{sub 0.7}Fe{sub 2}, the typical composition of Terfenol-D GMMs, has coexistence of rhombohedral and tetragonal phases over a wide temperature range in the vicinity of MPB. High resolution transmission electron microscopy provides direct evidence for local rhombohedral symmetry of the ferromagnetic phase and reveals regular-shaped nanoscale domains below 10 nm. The nano-sized structural/magnetic domains are hierarchically inside a single micron-sized stripe-like domain with the same average magnetization direction. Such domain structures are consistent with the low magnetocrystalline anisotropy and easy magnetic/structural domain switching under magnetic field, thus generating large magnetostriction at low field.

  12. Variations of magnetocaloric effect and magnetoresistance across RCuGe (R=Tb, Dy, Ho, Er) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Sachin; Suresh, K.G., E-mail: suresh@phy.iitb.ac.in

    2015-10-01

    RCuGe (R=Tb–Er) compounds have been studied by structural, magnetic, magnetocaloric and magnetotransport measurements. All these compounds are iso-structural and show antiferromagnetic ordering below their Néel temperatures (T{sub N}). Except TbCuGe, all the studied compounds show large magnetocaloric effect (MCE), arising due to the field induced metamagnetic transition. They also show a sign reversal of magnetoresistance (MR) with change in temperature or field. The non-monotonic variation of the magnitude of MR is attributed to the competing effects of Lorentz force, changes in the spin disorder scattering and the spin fluctuations. - Highlights: • RCuGe (R=Tb–Er) compounds show low temperature antiferromagnetic ordering. • All compounds show field induced metamagnetic transitions. • These compounds show large magnetocaloric effect and magnetoresistance.

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

    Science.gov (United States)

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

    2016-10-01

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

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

    Science.gov (United States)

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

    2009-10-20

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

  15. Structural Study of a Doubly Ordered Perovskite Family NaLnCoWO6 (Ln = Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb): Hybrid Improper Ferroelectricity in Nine New Members.

    Science.gov (United States)

    Zuo, Peng; Colin, Claire V; Klein, Holger; Bordet, Pierre; Suard, Emmanuelle; Elkaim, Erik; Darie, Céline

    2017-07-17

    The compounds of the doubly ordered perovskite family NaLnCoWO6 (Ln = Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Yb) were synthesized by solid-state reaction, nine of which (Ln = Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Yb) are new phases prepared under high-temperature and high-pressure conditions. Their structural properties were investigated at room temperature by synchrotron X-ray powder diffraction and neutron powder diffraction. All of them crystallize in monoclinic structures, especially the nine new compounds have the polar space group P21 symmetry, as confirmed by second harmonic generation measurements. The P21 polar structures were decomposed and refined in terms of symmetry modes, demonstrating that the polar mode is induced by two nonpolar modes in a manner of Hybrid Improper Ferroelectricity. The amplitudes of these three major modes all increase with decreasing the Ln cation size. The spontaneous ferroelectric polarization is estimated from the neutron diffraction data of three samples (Ln = Y, Tb, and Ho) and can be as large as ∼20 μC/cm(2).

  16. Luminescence behaviors of Eu- and Dy-codoped alkaline earth metal aluminate phosphors through potassium carbonate coprecipitation

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Chen-Jui, E-mail: cjliang@fcu.edu.tw; Siao, Hao-Yi

    2016-07-01

    An electronic energy mechanism of activator and sensitizer was established to describe the luminescence behaviors of Eu- and Dy-codoped M(II)Al{sub 2}O{sub 4} (M(II) = Ba, Sr, Ca, Mg) phosphors through potassium carbonate coprecipitation. Experimental results demonstrated that the prepared phosphors exhibited superior crystallinity at a temperature lower than 950 °C. The phosphors are ordered according to emission intensity as follows Ca- > Ba- > Sr- > Mg-containing phosphors. The energy level for Eu{sup 2+} 4f{sup 6}5d{sup 1} → 4f{sup 7}, Eu{sup 3+4}D{sub 0} → {sup 7}F, and Dy{sup 3+4}F{sub 9/2} → {sup 6}H transitions and the effects of nephelauxetic and crystal field in Ba-, Sr-, and Ca-containing phosphors were discussed. The energy gap, (hv){sub em}, between 5d and 4f of Eu{sup 2+} ion is strongly affected by host composition, crystal field strength, and nephelauxetic effect. The infrared emission of 4f{sub 9/2} → 6h for Dy{sup 3+} is merely depend on the transfer of energy from Eu{sup 2+} upon excited. Ca-containing phosphor with maximum (hv){sub em} is attributed to the lowest bond length of Ca−O and highest ionization potential of Ca{sup 2+} ion, which leads to the effects of crystal field and nephelauxetic greater than that in the other phosphors. - Highlights: • The list of the collected figure captions: • Develop a new coprecipitation method to prepare high efficiency phosphors. • Obtain superior crystallinity with lower calcination temperature. • Luminescence behavior of Eu- and Dy-codoped on aluminate phosphors is discussed. • Investigate the effects of alkaline earth metal containing on crystal field and nephelauxetic.

  17. Magnetic, magetostrictive properties, spin reorientation and M(o)ssbauer effect of Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95 alloys

    Institute of Scientific and Technical Information of China (English)

    ZHENG XiaoPing; ZHANG PeiFeng; FAN DuoWang; LI FaShen

    2009-01-01

    The effect of Pr substitution for Dy on the magnetic and magnetostrictive properties, anisotropy, spinreorientation and Mossbauer effect of a series of Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95(x=0, 0.1, 0.20, 0.25, 0.30, 0.35) alloys at room temperature have been investigated. It was found that a small amount of Pr sub-stitution is beneficial to a decrease in the magnetocrystalline anisotropy for the Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95 alloys. The magnetostriction decreases drastically with increasing x and the magnetostrictive effect disappears for x0.2. However, the magnetostriction exhibits a slightly bigger value at x=0.1 than the free alloys and is saturated more easily with the magnetic field H. The saturation magnetization and Curie temperature decrease monotonously, but the spontaneous magnetostriction increases linearly with increasing x, whereas the spin reorientation temperature increases first, then decreases rapidly and reaches the maximum at x=0.1. The analysis of Mossbauer spectra indicated that the easy magnetization direction in the {110} plane deviates slightly from the main axis of symmetry with the Pr concentration x, namely spin reorientation. Compared with AI substitution for Fe, the effect of Pr substitution for Dy on spin reorientation is relatively small. The hyperfine field increases with Pr concentration increasing, and the isomer shifts and the quadrupole splitting (QS) show weak concen-tration dependence.

  18. Magnetic,magetostrictive properties,spin reorientation and Mssbauer effect of Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95 alloys

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The effect of Pr substitution for Dy on the magnetic and magnetostrictive properties, anisotropy, spin reorientation and Mssbauer effect of a series of Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95 (x=0,0.1,0.20,0.25,0.30,0.35) alloys at room temperature have been investigated. It was found that a small amount of Pr substitution is beneficial to a decrease in the magnetocrystalline anisotropy for the Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95 alloys. The magnetostriction decreases drastically with increasing x and the magnetostrictive effect disappears for x>0.2. However, the magnetostriction exhibits a slightly bigger value at x=0.1 than the free alloys and is saturated more easily with the magnetic field H. The saturation magnetization and Curie temperature decrease monotonously, but the spontaneous magnetostriction increases linearly with increasing x, whereas the spin reorientation temperature increases first, then decreases rapidly and reaches the maximum at x=0.1. The analysis of Mssbauer spectra indicated that the easy magnetization direction in the {110} plane deviates slightly from the main axis of symmetry with the Pr concentration x, namely spin reorientation. Compared with Al substitution for Fe, the effect of Pr substitution for Dy on spin reorientation is relatively small. The hyperfine field increases with Pr concentration increasing, and the isomer shifts and the quadrupole splitting (QS) show weak concentration dependence.

  19. Magnetic Behaviour of Tb/Si Nanoscale Multilayers with Small Thickness of Rare Earth Layers

    Institute of Scientific and Technical Information of China (English)

    A.V.Svalov; V.O.Vas'kovskiy; G.V.Kurlyandskaya; J.M.Barandiaran; N.N.Schegoleva; A.N.Sorokin

    2007-01-01

    We report the magnetic properties of Tb/Si multilayers obtained by rf-sputtering at the Tb layer thickness LTb = 3 nm. Analysis of the magnetization processes indicates more complex behaviour than canonical spin-glass transition. It is more probable that these multilayers contain both Tb superparamagnetic particles and Tb-Si spin-glass alloys.

  20. Hyperfine interactions and electronic band structure in Tb{sub 0.27}Dy{sub 0.73}(Fe{sub 1-x}Co{sub x}){sub 2} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Bodnar, W.; Szklarska - Lukasik, M. [Faculty of Physics and Applied Computer Science, AGH, Al. Mickiewicza 30, 30-059 Krakow (Poland); Stoch, P. [Institute of Atomic Energy, 05-400 Swierk-Otwock (Poland); Faculty of Material Science and Ceramics, AGH, Al. Mickiewicza 30, 30-059 Krakow (Poland); Zachariasz, P. [Institute of Atomic Energy, 05-400 Swierk-Otwock (Poland); Pszczola, J., E-mail: pszczola@agh.edu.p [Faculty of Physics and Applied Computer Science, AGH, Al. Mickiewicza 30, 30-059 Krakow (Poland); Suwalski, J. [Institute of Atomic Energy, 05-400 Swierk-Otwock (Poland)

    2010-04-30

    The after-effects of Fe/Co substitution in the intermetallic series Tb{sub 0.27}Dy{sub 0.73}(Fe{sub 1-x}Co{sub x}){sub 2}, with a starting compound Tb{sub 0.27}Dy{sub 0.73}Fe{sub 2} known as Terfenol-D, were studied. Co substitution introduces a local area, at sub-nanoscale, with random Fe/Co neighbourhoods of the {sup 57}Fe atoms. {sup 57}Fe Moessbauer effect measurements for the intermetallic system Tb{sub 0.27}Dy{sub 0.73}(Fe{sub 1-x}Co{sub x}){sub 2} carried out at 4.2 K evidence an [100] easy axis of magnetization. Hyperfine interaction parameters: isomer shift, a magnetic hyperfine field and a quadrupole interaction parameter were obtained from the fitting procedure of the spectra, both for the local area and for the sample as bulk. As a result of Fe/Co substitution, a Slater-Pauling type curve for the average magnetic hyperfine field vs. Co content is observed. It is found that the magnetic hyperfine fields corresponding to the local area sorted out against Co contribution in the Fe/Co neighbourhoods also create a dependence similar to a Slater-Pauling type curve. Band structure calculations using the Full-Potential Linearized Augmented Plane Waves (FLAPW) method were performed. The experimentally determined magnetic hyperfine field correlates linearly with the weighted magnetic moment calculated per transition metal atom.

  1. A study of magnetostriction, spin reorientation, and Mssbauer spectra of Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 alloys with substitution of Fe by Al

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The effects of Al substitution for Fe on the structure, magnetics, magnetostriction, anisotropy and spin reorientation of a series of Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 alloys (x=0.05, 0.1, 0.15, 0.2, 0.25, 0.3) at room temperature have been investigated. The alloys of Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 substantially retain MgCu2-type C-15 cubic Laves phase structure when x<0.2. The mixed phases appear with x = 0.2, and cubic Laves phase decreases with increasing x. The magnetostriction of the Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 alloys decreases drastically with increasing x and the giant magnetostrictive effect disappears for x > 0.15. Fortunately, a small amount of Al substitution is beneficial to a decrease in the magnetocrystalline anisotropy. The spin reorientation temperature decreases with increasing x. The analysis of the Mssbauer spectra indicates that the easy magnetization direction in the {110} plane deviates slightly from the main axis of symmetry with the increase of Al concentration x, namely, spin reorientation, resulting in the change of macroscopical magnetic properties and magnetostriction. The hyperfine field decreases, but the isomer shifts increases with Al concentration increasing and the quadruple splitting QS shows a weak concentration dependence.

  2. 蔺草新型染土固色中试试验%The Pilot Test of Rush's Color Fixation by Modified Dyed Earth

    Institute of Scientific and Technical Information of China (English)

    王志锋; 鲁闯; 李建伟; 朱利萍; 王尚军

    2011-01-01

    Addition agents such as nano TiO2 and natural chlorophyl and so on were used to modify the dyed earth. And a pilot test of 2 000 kg rush's color fixation by modified dyed earth was carried out with conventional fixation technology. Apparent color, color fastness to artificial light, color fastness to rubbing and the dosage of dyed earth of rust before and after color fixated by modified dyed earth were compared. The results showed that apparent color and color fastness of the rush after color fixated by modified dyed earth were the same as the rust before color fixated by modified dyed earth. And the consumption of dyed earth was decreased over 70% than conventional technology. The new technology could not only decrease the production cost but also improve the working environment effectively.%利用纳米二氧化钛、天然叶绿素等添加物对现用蔺草固色用染土进行改性,在不改变固色工艺的条件下,利用新型染土进行批次固色规模为2 000kg蔺草的中试试验.对染土改性前后蔺草的表现颜色、耐人造光色牢度、耐摩擦色牢度以及染土的用量等进行了对比分析.结果表明,利用改性后的染土进行蔺草固色,蔺草的表现颜色、耐人造光色牢度及耐摩擦色牢度与原染土相当,同时实际染土用量可降低70%以上.该技术不仅可以节约大量的生产成本,作业环境也会因此得到改善.

  3. Effect of solvent on luminescence properties of re-dispersible LaF3∶Ln3+ (Ln3+=Eu3+,Dy3+,Sm3+ and Tb3+) nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Ganngam Phaomei; W.Rameshwor Singh

    2013-01-01

    LaF3∶Ln3+ (Eu3+,Dy3+,Sm3+ and Tb3+) nanoparticles were prepared in different solvents such as water,EG (ethylene glycol),DMSO (dimethyl sulfoxide) and their mixed solvents at a relatively low temperature of 150 ℃ by simple chemical route.All the prepared samples showed hexagonal phase and exhibited spherical morphology.The highest luminescence intensity was observed for the samples prepared in EG than the samples prepared in other solvents.However,the sample prepared in water showed anomalously higher luminescence intensity than that of the sample prepared in DMSO.

  4. Synthesis, luminescence and photometric characteristics of Ca{sub 0.5}La(MoO{sub 4}){sub 2}:Ln{sup 3+} (Ln = Eu, Tb, Dy) phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Krishnan, Rajagopalan [Department of Physics, B. S. Abdur Rahman University, Vandalur, Chennai 600048, Tamil Nadu (India); Thirumalai, Jagannathan, E-mail: jthirumalai@bsauniv.ac.in [Department of Physics, B. S. Abdur Rahman University, Vandalur, Chennai 600048, Tamil Nadu (India); Mahalingam, Venkatakrishnan [Department of Physics, B. S. Abdur Rahman University, Vandalur, Chennai 600048, Tamil Nadu (India); Mantha, Srinivas [Department of ECE, SASTRA University, Tirumalaisamudram, Thanjavur 613401 (India); Lavanya, Manthramoorthy [Department of Physics, B. S. Abdur Rahman University, Vandalur, Chennai 600048, Tamil Nadu (India)

    2015-07-15

    Ca{sub 0.5}La(MoO{sub 4}){sub 2}:Ln{sup 3+} phosphors, where Ln = 4, 8, 12, 16, and 20 mol% of Eu, Tb, or Dy, were successfully synthesized by a conventional solid-state reaction method at 900 °C for 3 h. The Ca{sub 0.5}La(MoO{sub 4}){sub 2}:Ln{sup 3+} phosphors exhibit a scheelite tetragonal crystal structure belonging to the I4{sub 1}/a space group. The strong absorption bands seen in Fourier transform infrared (FTIR) spectra confirm that F{sub 2}(ν{sub 3}) modes of vibration are IR active. The photoluminescence(PL) spectra reveal that, under optical excitation, the as-synthesized phosphors show high intensity narrow emission bands in the red (615 nm), and green (545 nm), and yellow (570 nm) regions for samples doped with Eu{sup 3+}, Tb{sup 3+}, and Dy{sup 3+} ions, respectively. The critical concentrations of Eu{sup 3+}, Tb{sup 3+}, and Dy{sup 3+} as dopants in Ca{sub 0.5}La(MoO{sub 4}){sub 2} were found to be 16, 12 and 12 mol%, respectively. Thereafter, concentration quenching effect occurred in the solid solutions. The fluorescence decay times for the major transitions of {sup 5}D{sub 0} → {sup 7}F{sub 2}, {sup 5}D{sub 4} → {sup 7}F{sub 5}, and {sup 4}F{sub 9/2} → {sup 6}H{sub 13/2} were estimated for different doping concentrations of Eu{sup 3+}, Tb{sup 3+}, and Dy{sup 3+} in Ca{sub 0.5}La(MoO{sub 4}){sub 2}, respectively. To determine the color purity and emission quality of the phosphor, photometric parameters such as color chromaticity coordinates, color correlated temperature (CCT), color rendering index (CRI), and luminous efficacy of radiation (LER) were estimated using the spectral energy distribution functions of the Ca{sub 0.5}La(MoO{sub 4}){sub 2}:Ln{sup 3+} phosphors. - Graphical abstract: Display Omitted - Highlights: • Single crystalline ceramic phosphor Ca{sub 0.5}La(MoO{sub 4}){sub 2}:Ln{sup 3+} were successfully synthesized. • The phosphor exhibits scheelite tetragonal crystal structure with space group I41/a. • Luminescence

  5. Magnetism and exchange interaction of small rare-earth clusters; Tb as a representative

    CERN Document Server

    Peters, Lars; Sanyal, Biplab; van Dijk, Chris; Bowlan, John; de Heer, Walt; Delin, Anna; Di Marco, Igor; Eriksson, Olle; Katsnelson, Mikhail I; Johansson, Börje; Kirilyuk, Andrei

    2016-01-01

    Here we follow, both experimentally and theoretically, the development of magnetism in Tb clusters from the atomic limit, adding one atom at a time. The exchange interaction is, surprisingly, observed to drastically increase compared to that of bulk, and to exhibit irregular oscillations as a function of the interatomic distance. From electronic structure theory we find that the theoretical magnetic moments oscillate with cluster size in exact agreement with experimental data. Unlike the bulk, the oscillation is not caused by the RKKY mechanism. Instead, the inter-atomic exchange is shown to be driven by a competition between wave-function overlap of the 5d shell and the on-site exchange interaction, which leads to a competition between ferromagnetic double-exchange and antiferromagnetic super-exchange. This understanding opens up new ways to tune the magnetic properties of rare-earth based magnets with nano-sized building blocks.

  6. Sensitivity of magnetic properties to chemical pressure in lanthanide garnets Ln 3 A 2 X 3O12, Ln  =  Gd, Tb, Dy, Ho, A  =  Ga, Sc, In, Te, X  =  Ga, Al, Li

    Science.gov (United States)

    Mukherjee, P.; Sackville Hamilton, A. C.; Glass, H. F. J.; Dutton, S. E.

    2017-10-01

    A systematic study of the structural and magnetic properties of three-dimensionally frustrated lanthanide garnets Ln 3 A 2 X 3O12, Ln  =  Gd, Tb, Dy, Ho, A  =  Ga, Sc, In, Te, X  =  Ga, Al, Li is presented. Garnets with Ln  =  Gd show magnetic behaviour consistent with isotropic Gd3+ spins; no magnetic ordering is observed for T  ⩾  0.4 K. Magnetic ordering features are seen for garnets with Ln  =  Tb, Dy, Ho in the temperature range 0.4  Tb, Dy, Ho.

  7. Magnetostriction, spin reorientation and Mssbauer study of Tb0.3Dy0.7(Fe1-xAlx)1.95 intermetallic compounds%Tb0.3Dy0.7(Fe1-xAlx)1.95合金的磁致伸缩、自旋重取向和穆斯堡尔谱研究

    Institute of Scientific and Technical Information of China (English)

    郑小平; 薛德胜; 李发伸; 成昭华; 吴光恒; 沈保根

    2002-01-01

    系统研究了室温下Tb0.3Dy0.7(Fe1-xAlx)1.95(x=0,0.05,0.1,0.15,0.2,0.25,0.3,0.35)合金中金属Al替代Fe对晶体结构、磁致伸缩、各向异性和自旋重取向的影响.结果发现,x0.15时超磁致伸缩效应消失;x0.15时,合金在室温下呈现顺磁性.

  8. Magnetic interactions in CuII-LnIII cyclic tetranuclear complexes: is it possible to explain the occurrence of SMM behavior in CuII-TbIII and CuII-DyIII complexes?

    Science.gov (United States)

    Hamamatsu, Takefumi; Yabe, Kazuya; Towatari, Masaaki; Osa, Shutaro; Matsumoto, Naohide; Re, Nazzareno; Pochaba, Andrzej; Mrozinski, Jerzy; Gallani, Jean-Louis; Barla, Alessandro; Imperia, Paolo; Paulsen, Carley; Kappler, Jean-Paul

    2007-05-28

    An extensive series of tetranuclear CuII2LnIII2 complexes [CuIILLnIII(hfac)2]2 (with LnIII being all lanthanide(III) ions except for the radioactive PmIII) has been prepared in order to investigate the nature of the CuII-LnIII magnetic interactions and to try to answer the following question: What makes the CuII2TbIII2 and CuII2DyIII2 complexes single molecule magnets while the other complexes are not? All the complexes within this series possess a similar cyclic tetranuclear structure, in which the CuII and LnIII ions are arrayed alternately via bridges of ligand complex (CuIIL). Regular SQUID magnetometry measurements have been performed on the series. The temperature-dependent magnetic susceptibilities from 2 to 300 K and the field-dependent magnetizations from 0 to 5 T at 2 K have been measured for the CuII2LnIII2 and NiII2LnIII2 complexes, with the NiII2LnIII2 complex containing diamagnetic NiII ions being used as a reference for the evaluation of the CuII-LnIII magnetic interactions. These measurements have revealed that the interactions between CuII and LnIII ions are very weakly antiferromagnetic if Ln=Ce, Nd, Sm, Yb, ferromagnetic if Ln=Gd, Tb, Dy, Ho, Er, Tm, and negligible if Ln=La, Eu, Pr, Lu. With the same goal of better understanding the evolution of the intramolecular magnetic interactions, X-ray magnetic circular dichroism (XMCD) has also been measured on CuII2TbIII2, CuII2DyIII2, and NiII2TbIII2 complexes, either at the L- and M-edges of the metal ions or at the K-edge of the N and O atoms. Last, the CuII2TbIII2 complex exhibiting SMM behavior has received a closer examination of its low temperature magnetic properties down to 0.1 K. These particular measurements have revealed the unusual very slow setting-up of a 3D order below 0.6 K.

  9. Effect of microstructure and texture on the magnetic and magnetocaloric properties of the melt-spun rare earth intermetallic compound DyNi

    Science.gov (United States)

    Rajivgandhi, R.; Chelvane, J. Arout; Nigam, A. K.; Park, Je-Geun; Malik, S. K.; Nirmala, R.

    2016-11-01

    Magnetization measurements have been carried out on the melt-spun ribbon sample of the rare earth intermetallic compound DyNi (Orthorhombic, FeB-type, Space group Pnma) and its magnetic and magnetocaloric properties are compared with those of the arc-melted analog. The arc-melted DyNi orders ferromagnetically at around 61 K (TC) whereas the melt-spun DyNi orders ferromagnetically at about 47 K. The maximum isothermal magnetic entropy change, ∆Smmax , near TC of the arc-melted and the melt-spun DyNi is found to be -32.7 J/kg K and -22.4 J/kg K, respectively, for a field change of 140 kOe. For low magnetic field changes of ~20 kOe, the relative cooling power (RCP) is ~660 J/kg for the arc melted DyNi and ~460 J/kg for the melt-spun ribbon. The reduction in TC and magnetocaloric effect may be attributed to the microstructure-induced anisotropy developed during the melt-spinning process.

  10. Hydrothermal synthesis, structure, and optical properties of two nanosized Ln26 @CO3 (Ln=Dy and Tb) cluster-based lanthanide-transition-metal-organic frameworks (Ln MOFs).

    Science.gov (United States)

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

    2015-02-16

    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, β=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, α=81.9990(10)°, β=88.0830(10)°, γ=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.

  11. Electronic and optical properties of rare earth trifluorides RF{sub 3} (R La, Ce, Pr, Nd, Gd and Dy)

    Energy Technology Data Exchange (ETDEWEB)

    Saini, Sapan Mohan [National Institute of Technology Raipur (C.G.) (India); Nautiyal, Tashi, E-mail: tashifph@iitr.ernet.in [Indian Institute of Technology Roorkee, Roorkee (U.K.) (India); Auluck, Sushil [Indian Institute of Technology Roorkee, Roorkee (U.K.) (India)

    2011-09-15

    Highlights: {yields} The electronic structure and optical properties of some rare earth trifluorides. {yields} Band structure and optical properties indicate these are large band gap insulators. {yields} The 4f electrons do not play a decisive role in the optical properties of these. - Abstract: This work presents the electronic structure and optical properties of some rare earth trifluorides (RF{sub 3}) coarsely covering a large range of rare-earths with R La, Ce, Pr, Nd, Gd and Dy. Our theoretical investigations are based on the first principles, using the full potential linearized augmented plane wave method with the inclusion of spin orbit coupling. The local spin density approximation (LSDA) and the Coulomb-corrected LSDA + U method have been employed. We find that the standard LSDA approach is incapable of correctly describing the electronic properties of such materials since it positions the f-bands incorrectly resulting in an incorrect metallic ground state. On the other hand, LSDA + U approximation, known for treating the highly correlated 4f electrons properly, is able to reproduce the correct insulating ground state. Interestingly, however, we do not find any significant differences in the optical properties calculated using LSDA and LSDA + U suggesting that the 4f electrons do not play a decisive role in the optical properties of these compounds. The reflectivity for all the compounds stays low till {approx}7 eV which is consistent with their large energy gaps. The calculated energy gaps are in good agreement with experiments. Our calculated reflectivity compares well with the experimental data and the results are analyzed in the light of band to band transitions.

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

    Science.gov (United States)

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

    2014-11-01

    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 λ(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 λ(exci)  = 331 nm (((7)F6 → (5)D1). TL spectra show that Eu(3+) and Tb(3+) ions affect TL sensitivity.

  13. Tetranuclear hetero-metal [Co(II)2Ln(III)2] (Ln = Gd, Tb, Dy, Ho, La) complexes involving carboxylato bridges in a rare μ4-η(2):η(2) mode: synthesis, crystal structures, and magnetic properties.

    Science.gov (United States)

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

    2014-02-01

    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 μ4-η(2):η(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 (τ0 = 2.0 × 10(-7) s) at BDC = 0, and U/kB = 7.8 K (τ0 = 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 τ0 = 2.75 × 10(-7) s.

  14. PF131010 Ciechanow fireball - the body possible related to Near Earth Asteroids 2010 TB54 and 2010 SX11

    CERN Document Server

    Olech, A; Wisniewski, M; Rudawska, R; Laskowski, J; Polakowski, K; Maciejewski, M; Krzyzanowski, T; Fajfer, T; Tyminski, Z

    2015-01-01

    On 2010 October 13, the Apollo type 20-meter asteroid 2010 TB54 passed within 6.1 lunar distances from the Earth. On the same date, but 11.4 hours earlier, exactly at 02:52:32 UT, the sky over central Poland was illuminated by -8.6 magnitude PF131010 Ciechanow fireball. The trajectory and orbit of the fireball was computed using multi-station data of Polish Fireball Network (PFN). The results indicate that the orbit of the meteoroid which caused the PF131010 fireball is similar to the orbit of 2010 TB54 asteroid and both bodies may be related. Moreover, two days before appearance of Ciechanow fireball another small asteroid denoted as 2010 SX11 passed close to the Earth-Moon system. Its orbit is even more similar to the orbit of Ciechanow fireball parent body than in case of 2010 TB54. The PF131010 Ciechanow entered Earth's atmosphere with the velocity of 12.9 +\\- 0.2 km/s and started to shine at height of 82.5 +\\- 0.3 km. Clear deceleration started after first three seconds of flight, and the terminal veloci...

  15. <1 1 0> Directional growth of polycrystalline magnetostrictive Tb{sub x}Dy{sub 1-x}Fe{sub y} compounds by casting in a strong unidirectional gradient

    Energy Technology Data Exchange (ETDEWEB)

    Bonino, Olivier E-mail: bonino@labs.polycnrs-gre.frolivier.bonino@cea.fr; Rango, Patricia de; Tournier, Robert

    2000-03-01

    Rods of highly magnetostrictive polycrystalline Tb{sub x}Dy{sub 1-x}Fe{sub y} materials are elaborated by casting in a cylindrical mould with cooling imposed from the bottom which leads to a fast vertical unidirectional growth. A <1 1 0> orientation is obtained along the axis of the rods parallel to the growth direction. The magnetostrictive properties are remarkable along the rods axis comparable to those of <1 1 1> rods. The saturated magnetostriction measured in a parallel magnetic field is {lambda}{sub parallel}=1124x10{sup -6} under 0 MPa and increases to 1760x10{sup -6} under a compressive stress of 25 MPa. The pseudolinear variation of the magnetostriction with the internal magnetic field {delta}{lambda}{sub parallel}/{mu}{sub 0}{delta}H{sub int} reaches 640x10{sup -6}/0.04 T under 9.9 MPa. The texture and the good magnetostrictive properties are reproducible.

  16. Role of Lanthanide-Ligand bonding in the magnetization relaxation of mononuclear single-ion magnets: A case study on Pyrazole and Carbene ligated LnIII(Ln=Tb, Dy, Ho, Er) complexes

    Indian Academy of Sciences (India)

    TULIKA GUPTA; GUNASEKARAN VELMURUGAN; THAYALAN RAJESHKUMAR; GOPALAN RAJARAMAN

    2016-10-01

    Ab initio CASSCF+RASSI-SO+SINGLE_ANISO and DFT based NBO and QTAIM investigations were carried out on a series of trigonal prismatic M(BcMe)₃ (M = Tb(1), Dy(2), Ho(3), Er(4), [BcMe]⁻ = dihydrobis (methylimidazolyl) borate) and M(BpMe)₃ (M = Tb(1a), Dy(2a), Ho(3a), Er(4a) [BpMe]⁻ = dihydrobis (methypyrazolyl) borate) complexes to ascertain the anisotropic variations of these two ligand field environments and the influence of Lanthanide-ligand bonding on the magnetic anisotropy. Among all the complexes studied, only 1 and 2 show large Ucal (computed energy barrier for magnetization reorientation) values of 256.4 and 268.5 cm⁻¹, respectively and this is in accordance with experiment. Experimentally only frequency dependent χ” tails are observed for complex 1a and our calculation predicts a large Ucalof 229.4 cm⁻¹ for this molecule. Besides these, none of the complexes (3, 4, 2a, 3a and 4a) computed to possess large energy barrier and this is affirmed by the experiments. These observed differences in the magnetic properties are correlated to the Ln-Ligand bonding. Our calculations transpire comparatively improved Single-Ion Magnet (SIM) behaviour for carbene analogues due to the more axially compressed trigonal prismatic ligand environment. Furthermore, our detailed Mulliken charge, spin density, NBO and Wiberg bond analysis implied stronger Ln...H–BH agostic interaction for pyrazole analogues. Further, QTAIM analysis reveals the physical nature of coordination, covalent, and fine details of the agostic interactions in all the eight complexes studied. Quite interestingly, for the first time, using the Laplacian density, we are able to quantify the prolate and oblate nature of the electron clouds in lanthanides and this is expected to have a far reaching outcome beyond the examples studied.

  17. 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.

    Science.gov (United States)

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

    2014-12-15

    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 -ΔSm = 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.

  18. Planar tetranuclear Dy(III) single-molecule magnet and its Sm(III), Gd(III), and Tb(III) analogues encapsulated by salen-type and β-diketonate ligands.

    Science.gov (United States)

    Yan, Peng-Fei; Lin, Po-Heng; Habib, Fatemah; Aharen, Tomoko; Murugesu, Muralee; Deng, Zhao-Peng; Li, Guang-Ming; Sun, Wen-Bin

    2011-08-01

    The syntheses, structures, and magnetic properties are reported for four new lanthanide clusters [Sm(4)(μ(3)-OH)(2)L(2)(acac)(6)]·4H(2)O (1), [Gd(4)(μ(3)-OH)(2)L(2)(acac)(6)]·4CH(3)CN (2), and [Ln(4)(μ(3)-OH)(2)L(2)(acac)(6)]·2H(2)L·2CH(3)CN (3, Ln = Tb; 4, Ln = Dy) supported by salen-type (H(2)L = N,N'-bis(salicylidene)-1,2-cyclohexanediamine) and β-diketonate (acac = acetylacetonate) ligands. The four clusters were confirmed to be essentially isomorphous by infrared spectroscopy and single-crystal X-ray diffraction. Their crystal structures reveal that the salen-type ligand provides a suitable tetradentate coordination pocket (N(2)O(2)) to encapsulate lanthanide(III) ions. Moreover, the planar Ln(4) core is bridged by two μ(3)-hydroxide, four phenoxide, and two ketonate oxygen atoms. Magnetic properties of all four compounds have been investigated using dc and ac susceptibility measurements. For 4, the static and dynamic data indicate that the Dy(4) complex exhibits slow relaxation of the magnetization below 5 K associated with single-molecule magnet behavior.

  19. Hetero-metallic {3d-4f-5d} complexes: preparation and magnetic behavior of trinuclear [(L(Me2)Ni-Ln){W(CN)(8)}] compounds (Ln = Gd, Tb, Dy, Ho, Er, Y; L(Me2) = Schiff base) and variable SMM characteristics for the Tb derivative.

    Science.gov (United States)

    Sutter, Jean-Pascal; Dhers, Sébastien; Rajamani, Raghunathan; Ramasesha, S; Costes, Jean-Pierre; Duhayon, Carine; Vendier, Laure

    2009-07-06

    Assembling bimetallic {Ni-Ln}(3+) units and {W(CN)(8)}(3-) is shown to be an efficient route toward heteronuclear {3d-4f-5d} compounds. The reaction of either the binuclear [{L(Me2)Ni(H(2)O)(2)}{Ln(NO(3))(3)}] complexes or their mononuclear components [L(Me2)Ni] and Ln(NO(3))(3) with (HNBu(3))(3){W(CN)(8)} in dmf followed by diffusion of tetrahydrofuran yielded the trinuclear [{L(Me2)NiLn}{W(CN)(8)}] compounds 1 (Ln = Y), 2a,b (Gd), 3a,b (Tb), 4 (Dy), 5 (Ho), and 6 (Er) as crystalline materials. All of the derivatives possess the trinuclear core resulting from the linkage of the {W(CN)(8)} to the Ni center of the {Ni-Ln} unit. Differences are found in the solvent molecules acting as ligands and/or in the lattice depending on the crystallization conditions. For all the compounds ferromagnetic {Ni-W} and {Ni-Ln} (Ln = Gd, Tb, Dy, and Er} interactions are operative resulting in high spin ground states. Parameterization of the magnetic behaviors for the Y and Gd derivatives confirmed the strong cyano-mediated {Ni-W} interaction (J(NiW) = 27.1 and 28.5 cm(-1)) compared to the {Ni-Gd} interaction (J(NiGd) = 2.17 cm(-1)). The characteristic features for slow relaxation of the magnetization are observed for two Tb derivatives, but these are modulated by the crystal phase. Analysis of the frequency dependence of the alternating current susceptibility data yielded U(eff)/k(B) = 15.3 K and tau(0) = 4.5 x 10(-7) s for one derivative whereas no maxima of chi(M)'' appear above 2 K for the second one.

  20. Structural transformation studies on the rare earth containing Heusler alloys Pd 2RESn

    Science.gov (United States)

    Umarji, A. M.; Malik, S. K.; Shenoy, G. K.

    1985-03-01

    The Heusler alloys Pd 2RESn form for rare-earths (RE) from Tb to Lu and for Sc and Y. Of these, the alloys containing Yb, Tm, Lu, Sc and Y are superconducting. We have carried out structural studies on all these alloys by studying the temperature dependence of the X-ray patterns in the temperature range 5 to 300 K. Some nonstoichiometric compositions were also investigated. Structural transformation is observed only in Tb and Dy containing alloys while none of the superconducting alloys show a transformation. The transformation temperature is lowered by about 50 K in going from stoichiometric Pd 2TbSn to nonstoichiometric Pd 2Tb 0.95Sn while it is completely suppressed in Pd 2Dy 0.95Sn. Magnetic and Mössbauer studies on Dy compound are also reported.

  1. Synthesis and Characterization of Rare Earth Complexes of Ferrocenylcarbonylhydrazine

    Institute of Scientific and Technical Information of China (English)

    边占喜; 董彬; 李保国

    2002-01-01

    Rare earth complexes of ferrocenylcarbonylhydrazine Ln(FH)x(ClO4)3*nH2O (where Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, x=3; Ln = Er, Tm, Yb, Lu, x=4; n=2~6, FH=ferrocenylcarbonylhydrazin) were synthesized and characterized by elemental analyses, MS, IR and 1H NMR spectra. The ligand FH is bidentate, coordinating through the carbonyl oxygen and the amino nitrogen atom. The redox properties of the ligand and its complexes were investigated using cyclic voltammetric method. The solid state fluorescence spectra of Sm, Tb and Dy complexes were also studied.

  2. Canted magnetic ground state of quarter-doped manganites R 0.75Ca0.25MnO3 (R  =  Y, Tb, Dy, Ho, and Er)

    Science.gov (United States)

    Sinclair, R.; Cao, H. B.; Garlea, V. O.; Lee, M.; Choi, E. S.; Dun, Z. L.; Dong, S.; Dagotto, E.; Zhou, H. D.

    2017-02-01

    Polycrystalline samples of the quarter-doped manganites R 0.75Ca0.25MnO3 (R  =  Y, Tb, Dy, Ho, and Er) were studied by x-ray diffraction and AC/DC susceptibility measurements. All five samples are orthorhombic and exhibit similar magnetic properties: enhanced ferromagnetism below T 1 (∼80 K) and a spin glass (SG) state below T SG (∼30 K). With increasing R 3+ ionic size, both T 1 and T SG generally increase. The single crystal neutron diffraction results on Tb0.75Ca0.25MnO3 revealed that the SG state is mainly composed of a short-range ordered version of a novel canted (i.e. noncollinear) antiferromagnetic spin state. Furthermore, calculations based on the double exchange model for quarter-doped manganites reveal that this new magnetic phase provides a transition state between the ferromagnetic state and the theoretically predicted spin-orthogonal stripe phase.

  3. Effect of cobalt substitution on magnetic properties and microstructure of nanocrystalline (NdDyTb)12.3(FeZrNbCu)81.7B6.0ribbons

    Institute of Scientific and Technical Information of China (English)

    BAO Xiaoqian; GAO Xuexu; ZHANG Maocai; ZHU Jie; ZHOU Shouzeng

    2009-01-01

    Effect of Co substitution and annealing treatment on the formation, magnetic properties and microstructure of (NdOyTb)12.3(FeZrNbCu)81.7CoxB6(x=0-15) ribbons prepared by rapid quenching and subsequent annealing was systematically investi-gated by means of differential scanning calorimeter (DSC), X-ray diffraction (XRD), high resolution scanning electron microscopy (HRSEM) and vibrating sample magnetometer (VSM). Phase analysis revealed single-phase material. The remanence polarization Jr and maximum en-ergy product (BH)max increased with increasing x from 0 to 12 and then decreased for x=lS. The intrinsic coercivity Hci of (NdDyTb)12.3 (FeZrNbCU)81.7-xCoxB6 ribbons optimally processed decreased from 1308.7 kA/m for x=0 to 817.4 kA/m for x=15. Optimum magnetic properties with Jr=1.041 T, Hci=944.9 kA/m and (BH)max=155.1 kJ/m3 were achieved by annealing melt-spun ribbon (x=-12) at 675℃ for 10 min. There was no significant influence of Co substitution on microstructure.

  4. Transferred hyperfine interaction between the rare-earth ions and the fluorine nuclei in rare-earth trifluorides

    DEFF Research Database (Denmark)

    Hansen, P. E.; Nevald, Rolf; Guggenheim, H. G.

    1978-01-01

    The isotropic and anisotropic transferred hyperfine interactions between F ions in the two chemically inequivalent sites and the rare-earth ions (R) have been derived from 19F NMR measurements in the temperature region 100-300 K on single crystals of TbF3 and DyF3. The isotropic interactions...... are found to be negative and constant in this temperature region and with the numerical values decreasing slightly from TbF3 to DyF3. The anisotropic interactions, when the point dipole contributions are subtracted, are found to be substantially smaller and about equal for the two materials. The crystals...

  5. Hydrothermal synthesis, structure, and optical properties of two nanosized Ln{sub 26} rate at CO{sub 3} (Ln=Dy and Tb) cluster-based lanthanide-transition-metal-organic frameworks (Ln MOFs)

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yu; Huang, Lian; Miao, Hao; Wan, Hong Xiang; Mei, Hua; Liu, Ying [State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University (China); Xu, Yan [State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University (China); State Key Laboratory of Coordination Chemistry, Nanjing Tech University (China)

    2015-02-16

    Two Ln{sub 26} rate at CO{sub 3} (Ln=Dy and Tb) cluster-based lanthanide-transition-metal-organic frameworks (Ln MOFs) formulated as [Dy{sub 26}Cu{sub 3}(Nic){sub 24}(CH{sub 3}COO){sub 8}(CO{sub 3}){sub 11}(OH){sub 26}(H{sub 2}O){sub 14}]Cl . 3 H{sub 2}O (1; HNic=nicotinic acid) and [Tb{sub 26}NaAg{sub 3}(Nic){sub 27}(CH{sub 3}COO){sub 6}(CO{sub 3}){sub 11}(OH){sub 26}Cl(H{sub 2}O){sub 15}] . 7.5 H{sub 2}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) Aa, b=33.346(11) Aa, c=24.424(8) Aa, β=93.993(5) , V=29065(16) Aa{sup 3}, whereas 2 crystallizes in the triclinic space group P anti 1 with a=20.4929(19) Aa, b=24.671(2) Aa, c=29.727(3) Aa, α=81.9990(10) , β=88.0830(10) , γ=89.9940(10) , V=14875(2) Aa{sup 3}. Structural analysis indicates the framework of 1 is a 3D perovskite-like structure constructed out of CO{sub 3} rate at Dy{sub 26} building units and Cu{sup +} centers by means of nicotinic acid ligand bridging. In 2, however, nanosized CO{sub 3} rate at Tb{sub 26} units and [Ag{sub 3}Cl]{sup 2+} centers are connected by Nic{sup -} 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{sup -} to Tb{sup 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{sup -1} (1 GM = 10{sup -50} cm{sup 4} s photon{sup -1}), which indicates that compound 2 might be a good choice for third-order nonlinear optical materials. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Hybrid silica nanoparticles for sequestration and luminescence detection of trivalent rare-earth ions (Dy{sup 3+} and Nd{sup 3+}) in solution

    Energy Technology Data Exchange (ETDEWEB)

    Topel, Seda Demirel; Legaria, Elizabeth Polido [Swedish University of Agricultural Sciences (SLU), Department of Chemistry (Sweden); Tiseanu, Carmen [National Institute for Laser, Plasma and Radiation Physics (Romania); Rocha, João [University of Aveiro, Department of Chemistry CICECO (Portugal); Nedelec, Jean-Marie [Clermont Université, ENSCCF, Institute de Chimie de Clermont-Ferrand (France); Kessler, Vadim G.; Seisenbaeva, Gulaim A., E-mail: gulaim.seisenbaeva@slu.se [Swedish University of Agricultural Sciences (SLU), Department of Chemistry (Sweden)

    2014-12-15

    New hybrid material-based adsorbents acting also as luminescent probes upon uptake of trivalent rare-earth (RE) ions Nd{sup 3+} and Dy{sup 3+} have been developed. SiO{sub 2} NPs functionalized by three different organic ligands, N-aminopropylen-amido-iminodiacetic acid (L1), pyridine-α,β-dicarboxylic acid bis(propylenamide) (L2), and N-propylen-iminodiacetic acid (L3), have been produced and fully characterized by {sup 13}C, {sup 1}H, and {sup 29}Si solid-state NMR, FTIR, TGA, XRD, TEM, nitrogen gas adsorption, and also by NTA and DLS in solution. The synthesized hybrid materials are well dispersible and stable in aqueous solutions according to NTA and consist of spheres with diameters less than 100 nm. Their affinities to the lanthanide ions Dy{sup 3+} and Nd{sup 3+} have been investigated in aqueous solution and characterized by SEM–EDS and complexometric titration, demonstrating that they can be successfully used as adsorbents for sequestration of trivalent RE ions. The adsorbed RE ions can efficiently be desorbed from saturated nanoadsorbents by addition of hydrochloric acid. The produced nanomaterials may also be used as luminescent probes for Dy{sup 3+} and Nd{sup 3+} ions in solution.

  7. Combustion synthesis and luminescence characteristic of rare earth activated LiCaBO3

    Institute of Scientific and Technical Information of China (English)

    N.S. Bajaj; S.K. Omanwar

    2012-01-01

    Lithium calcium borate (LiCaBO3) polycrystalline thermoluminescence (TL) phosphor doped with rare earth (Tb3+ and Dy3+) elements was synthesized by novel solution combustion synthesis.The reaction produced very stable crystalline LiCaBO3:D (D=Tb3+ and Dy3+)phosphors.These rare earth doped phosphors material showed maximum TL sensitivity with favorable glow curve shape.TL glow curve of X-ray irradiated that LiCaBO3:Tb3+ and LiCaBO3:Dy3+ samples showed two major well-separated glow peaks.The TL sensitivity of these phosphors to X-ray radiation was comparable with that of TLD-100 (Harshaw).Photoluminescence spectra of LiCaBO3:Tb3+ and LiCaBO3:Dy3+ showed the characteristic Tb3+ and Dy3+ peaks respectively.TL response to X-ray radiation dose was linear up to 25 Gy.

  8. Solid-state synthesis and lanthanide photoluminescence of doped yttrium molybdo-antimonites, Y{sub 2−n}A{sub n}Mo{sub 4}Sb{sub 2}O{sub 18} (A=Pr, Sm, Eu, Tb, Dy, Ho, and Er; n=0.02–2) solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Mohitkar, Shrikant A.; Vidyasagar, K., E-mail: kvsagar@iitm.ac.in

    2015-05-15

    Abstract:: Y{sub 2−n}A{sub n}Mo{sub 4}Sb{sub 2}O{sub 18} (A=Pr, Sm, Eu, Tb, Dy, Ho, and Er; n=0.02–2) solid solutions were synthesized by a solid-state method and studied for their lanthanide photoluminescence. They show concentration dependent lanthanide photoluminescence and existence of concentration quenching phenomenon. The emission intensity and the fluorescence-lifetime are found to be highest for an optimum concentration of a given lanthanide ion in the solid solution series studied. The neat photoluminescence of A{sub 2}Mo{sub 4}Sb{sub 2}O{sub 18} (A=Pr, Sm, Eu, Tb, Dy, Ho, and Er) compounds involves partial concentration quenching. - Highlights: • Isostructural Y{sub 2−n}A{sub n}Mo{sub 4}Sb{sub 2}O{sub 18} (A=Pr, Sm, Eu, Tb, Dy, Ho, and Er; n=0.02–2) solid solutions have been synthesized. • Lanthanide photoluminescence of Y{sub 2−n}A{sub n}Mo{sub 4}Sb{sub 2}O{sub 18} (A=Pr, Sm, Eu, Tb, Dy, Ho, and Er; n=0.02–2) solid solutions has been studied. • Optimum concentration of each photoluminescent dopant for Y{sub 2−n}A{sub n}Mo{sub 4}Sb{sub 2}O{sub 18} (A=Pr, Sm, Eu, Tb, Dy, Ho, and Er; n=0.02 –2) solid solutions has been determined. • Red photoemission of Eu{sup 3+} in Y{sub 1.5}Eu{sub 0.5}Mo{sub 4}Sb{sub 2}O{sub 18} is visible to the naked eye. • Green photoemission of Tb{sup 3+} in Y{sub 1.7}Tb{sub 0.3}Mo{sub 4}Sb{sub 2}O{sub 18} is visible to the naked eye.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Tianyu, E-mail: maty@zju.edu.cn [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Key Laboratory of Novel Materials for Information Technology of Zhejiang Province, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou 310027 (China); Ferroic Physics Group, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Hu, Shanshan; Bai, Guohua; Yan, Mi; Lu, Yunhao, E-mail: luyh@zju.edu.cn [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Key Laboratory of Novel Materials for Information Technology of Zhejiang Province, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou 310027 (China); Li, Huiying [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, Xi' an Jiaotong University, Xi' an 710049 (China); Peng, Xiaoling [College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Ren, Xiaobing [Ferroic Physics Group, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, Xi' an Jiaotong University, Xi' an 710049 (China)

    2015-03-16

    Soluting rare earth atoms Tb or Dy into body centered cubic (BCC) Fe-Ga through rapid cooling significantly enhances the magnetostriction due to strong localized magnetocrystalline anisotropy. Origin of the local strong anisotropy, however, awaits comprehensive microstructural investigation. In this letter, formation of tetragonal nanoparticles with c/a ∼ 0.979 has been found in the giant magnetostrictive ribbons Fe{sub 82.89}Ga{sub 16.88}Tb{sub 0.23} due to local symmetry breaking of the BCC lattice using high resolution transmission electronic microscopy. First principal calculations suggest that random replacement of Tb atoms for Fe or Ga in the ordered DO{sub 3} superlattice is beneficial in the formation of such tetragonal symmetry. Exchange couplings between the nearest Tb-Fe or Tb-Tb pairs of the tetragonal nanoparticles might generate strong localized magnetocrystalline anisotropy, leading to extraordinary magnetostriction enhancement.

  10. Silver nanoparticles-enhanced rare earth co-luminescence effect of Tb(III)-Y(III)-dopamine system.

    Science.gov (United States)

    Li, Huihui; Wu, Xia

    2015-06-01

    It was found that silver nanoparticles (AgNPs) could enhance co-luminescence effect of rare earths ions Tb(3+) and Y(3+). Based on this, a sensitive fluorescence detection method for the determination of dopamine (DA) was proposed. Moreover, the detection limit for DA was very low (down to nM). This is because DA can remarkably enhance the luminescence intensity of the Tb(3+) ion by Y(3+) in the colloidal solution of AgNPs, forming a new co-luminescence system. Furthermore, based on the metal enhanced fluorescence (MEF), AgNPs can sensitize the co-luminescence effect of the complex of Tb(3+)-Y(3+)-DA. In a neutral buffer solution (pH 7.50), the luminescence intensity of the system was linearly related to the concentration of DA in the range of 2.0-100 nM, with a limit of detection as low as 0.57 nM. The proposed method was applied for the determination of DA in dopamine hydrochloride injections and human serum samples with good accuracy and satisfactory recovery. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Luminescence and magnetic behaviour of almond like (Na{sub 0.5}La{sub 0.5})MoO{sub 4}:RE{sup 3+} (RE = Eu, Tb, Dy) nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Krishnan, Rajagopalan [Department of Physics, B.S. Abdur Rahman University, Vandalur, Chennai, Tamil Nadu (India); Thirumalai, Jagannathan, E-mail: jthirumalai@bsauniv.ac.in [Department of Physics, B.S. Abdur Rahman University, Vandalur, Chennai, Tamil Nadu (India); Thomas, Sabu [Polymer Science and Technology, Center for Nanoscience and Nanotechnology, School of Chemical Sciences, Mahatma Gandhi University, Kottayam 686 560, Kerala (India); Gowri, Mahasampath [Department of Chemistry, B.S. Abdur Rahman University, Vandalur, Chennai, Tamil Nadu (India)

    2014-08-01

    Graphical abstract: Monodispersed almond-like (Na{sub 0.5}La{sub 0.5})MoO{sub 4}:RE{sup 3+} nanostructures synthesized by employing ethylene-diamine tetra acetic acid (EDTA) using hydrothermal route at 200 °C for 24 h. These nanoparticles were found to be novel bi-functional candidates suitable for high-quality luminescence and magnetic applications. - Highlights: • Almond like structures of (Na{sub 0.5}La{sub 0.5})MoO{sub 4}:RE{sup 3+} were synthesized by hydrothermal method. • Time dependent self-assembly could be the dominant process for the formation of 3D networks. • Luminescence properties of nanosamples were studied in comparison with bulk sample. • Room temperature magnetic properties of bulk and nanophosphors were investigated. - Abstract: Tetragonal phase (Na{sub 0.5}La{sub 0.5})MoO{sub 4}:RE{sup 3+} (RE = Eu, Tb, Dy) with almond like hierarchical structures assembled from nanosheets building blocks were successfully synthesized by employing disodium ethylenediaminetetraacetic acid (Na{sub 2}EDTA) using hydrothermal route at 200 °C for 24 h. Field emission scanning electron microscope, transmission electron microscope, and X-ray diffraction patterns were used to characterize the morphology, size, and crystal structure with good resolution. The sequestering agent EDTA acts as quadridentate ligand coordinated with metal ions [Na{sup +}, La{sup 3+}/RE{sup 3+}] facilitating the formation of self-organized 3D networks. The growth mechanism for the formation of almond like nanostructures is explicated in four paths: dissolution, adsorption, in situ transformation in acidic and basic media and the effective collision. Photoluminescence excitation and emission spectra reveals a spectral blue shift which was observed in the nanosamples towards shorter wavelengths compared with the bulk sample. Upon UV irradiation, both bulk and nanostructure show strong luminescence in the red region due to the {sup 5}D{sub 0} → {sup 7}F{sub 2} transition in Eu{sup 3

  12. Efficient dual-wavelength excitation of Tb3+ emission in rare-earth doped KYF4 cubic nanocrystals dispersed in silica sol-gel matrix

    Science.gov (United States)

    del-Castillo, J.; Yanes, A. C.; Santana-Alonso, A.; Méndez-Ramos, J.

    2014-11-01

    Energy transfer from Ce3+ to Tb3+ ions under UV excitation, giving rise to visible emissions, is investigated in sol-gel derived transparent nano-glass-ceramics containing cubic KYF4 nanocrystals, for different doping concentrations of rare-earth ions. Moreover, visible emissions of Tb3+ are also obtained under near-infrared excitation through energy transfer from Yb3+ ions by means of cooperative up-conversion processes. Thus, Ce3+-Tb3+-Yb3+ doped nano-glass-ceramics can be activated in a dual-wavelength mode yielding efficient blue-green emissions of particular interest in photovoltaic silicon solar cells and white-light emitting diodes.

  13. 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.

    Science.gov (United States)

    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

    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+) .

  14. The Dy-Zn phase diagram

    Science.gov (United States)

    Saccone, A.; Cardinale, A. M.; Delfino, S.; Ferro, R.

    2003-03-01

    The dysprosium-zinc phase diagram has been investigated over its entire composition range by using differential thermal analysis, (DTA) metallographic analysis, X-ray powder diffraction, and electron probe microanalysis (EPMA). Seven intermetallic phases have been found and their structures confirmed. DyZn, DyZn2, Dy13Zn58, and Dy2Zn17 melt congruently at 1095 °C, 1050 °C, 930 °C, and 930 °C, respectively. DyZn3, Dy3Zn11, and DyZn12 form through peritectic reactions at 895 °C, about 900 °C and 685 °C, respectively. Four eutectic reactions occur at 850 °C and 30.0 at pct Zn (between (Dy) and DyZn), 990 °C and 60.0 at pct Zn (between DyZn and DyZn2), 885 °C and 76.0 at pct Zn (between DyZn3 and Dy3Zn11), and 875 °C and 85.0 at pct Zn (involving Dy13Zn58 and Dy2Zn17). The Dy-rich end presents a catatectic equilibrium; a degenerate invariant effect has been found in the Zn-rich region. The phase equilibria of the Dy-Zn alloys are discussed and compared with those of the other known RE-Zn systems (RE=rare earth metal) in view of the regular change in the relative stabilities of the phases across the lanthanide series

  15. 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).

    Science.gov (United States)

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

    2012-11-28

    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.

  16. Construction of Polynuclear Lanthanide (Ln = Dy(III), Tb(III), and Nd(III)) Cage Complexes Using Pyridine-Pyrazole-Based Ligands: Versatile Molecular Topologies and SMM Behavior.

    Science.gov (United States)

    Bala, Sukhen; Sen Bishwas, Mousumi; Pramanik, Bhaskar; Khanra, Sumit; Fromm, Katharina M; Poddar, Pankaj; Mondal, Raju

    2015-09-08

    Employment of two different pyridyl-pyrazolyl-based ligands afforded three octanuclear lanthanide(III) (Ln = Dy, Tb) cage compounds and one hexanuclear neodymium(III) coordination cage, exhibiting versatile molecular architectures including a butterfly core. Relatively less common semirigid pyridyl-pyrazolyl-based asymmetric ligand systems show an interesting trend of forming polynuclear lanthanide cage complexes with different coordination environments around the metal centers. It is noteworthy here that construction of lanthanide complex itself is a challenging task in a ligand system as soft N-donor rich as pyridyl-pyrazol. We report herein some lanthanide complexes using ligand containing only one or two O-donors compare to five N-coordinating sites. The resultant multinuclear lanthanide complexes show interesting magnetic and spectroscopic features originating from different spatial arrangements of the metal ions. Alternating current (ac) susceptibility measurements of the two dysprosium complexes display frequency- and temperature-dependent out-of-phase signals in zero and 0.5 T direct current field, a typical characteristic feature of single-molecule magnet (SMM) behavior, indicating different energy reversal barriers due to different molecular topologies. Another aspect of this work is the occurrence of the not-so-common SMM behavior of the terbium complex, further confirmed by ac susceptibility measurement.

  17. Crystal structures of the R{sub 2}Pb{sub 3}Sn{sub 3}S{sub 12} (R = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er and Tm) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Gulay, L.D. [Department of General and Inorganic Chemistry, Volyn State University, Voli Avenue 13, 43009 Lutsk (Ukraine)], E-mail: gulay@univer.lutsk.ua; Ruda, I.P. [Department of General and Inorganic Chemistry, Volyn State University, Voli Avenue 13, 43009 Lutsk (Ukraine); Marchuk, O.V. [Department of Physical and Colloidal Chemistry, Volyn State University, Voli Avenue 13, 43009 Lutsk (Ukraine); Olekseyuk, I.D. [Department of General and Inorganic Chemistry, Volyn State University, Voli Avenue 13, 43009 Lutsk (Ukraine)

    2008-06-12

    The crystal structures of the R{sub 2}Pb{sub 3}Sn{sub 3}S{sub 12} (R = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er and Tm) compounds (space group Pmc2{sub 1}, Pearson symbol oP40, a = 0.38992 (1) nm, b = 2.01175 (7) nm, c = 1.15140 (4) nm, R{sub I} 0.0785 for Ho{sub 2}Pb{sub 3}Sn{sub 3}S{sub 12}) were investigated using X-ray powder diffraction. The R{sub 1} atoms are surrounded by trigonal prisms with two additional atoms, the R{sub 2} atoms by distorted octahedra with one additional atom. The Pb{sub 1} and Pb{sub 3} atoms are surrounded by trigonal prisms with one additional atom, the Pb{sub 2} atoms by trigonal prisms with two additional atoms. Octahedral surrounding exists for Sn{sub 1} and Sn{sub 2}. The Sn{sub 3} atoms are located in trigonal bipyramids. Four or five neighbours surround the S atoms.

  18. Substitution disorder and photoluminescent property of a new rare-earth borate: K{sub 3}TbB{sub 6}O{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Dan; Ma, Fa-Xue; Huang, Min; Chen, Peng-Fei; Zhang, Rong-Hua [Henan Polytechnic Univ., Jiaozuo (China). College of Chemistry and Chemical Engineering; Zhang, Rui-Juan [Henan Polytechnic University, Jiaozuo (China). Academic Affairs Office; Wei, Wei [Capital Normal Univ., Beijing (China). Dept. of Chemistry

    2016-11-01

    A new rare-earth borate K{sub 3}TbB{sub 6}O{sub 12} has been prepared using the high temperature molten salt method and was structurally determined by single crystal X-ray diffraction analyses. The structure features a three-dimensional (3D) framework which is composed of isolated B{sub 5}O{sub 10}, KO{sub 6}, KO{sub 8} and TbO{sub 6} groups. An atom site in the 3{sub 2} screw axis is shared by K and Tb atoms with the molar ratio of 1:1. The self-activated photoluminescence (PL) property of K{sub 3}TbB{sub 6}O{sub 12} was studied. Under the excitation of 378 nm, the emission spectrum exhibits an intense green emission centered at 543-548 nm with the chromaticity coordinates (0.342, 0.590), which can be assigned to the {sup 5}D{sub 4} → {sup 7}F{sub 5} transition of Tb{sup 3+}. The excitation spectra cover a wide range from 330 to 385 nm, which suggests that the K{sub 3}TbB{sub 6}O{sub 12} phosphors can be effectively excited by a near-UV light source. One may expect that compound K{sub 3}TbB{sub 6}O{sub 12} can be used as a green phosphor pumped by near-UV LED chips.

  19. On the single-ion Magnetic Anisotropy of the Rare-Earth Metals

    DEFF Research Database (Denmark)

    Kolmakova, N.P.; Tishin, A.M.; Bohr, Jakob

    1996-01-01

    The temperature dependences of the single-ion magnetic anisotropy constants for Tb and Dy metals are calculated in terms of the multipole moments of the rare-earth ions utilizing the available crystal-field parameters. The results are compared with the existing experimental data....

  20. Static magnetic susceptibility, crystal field and exchange interactions in rare earth titanate pyrochlores

    NARCIS (Netherlands)

    Malkin, B. Z.; Lummen, T. T. A.; van Loosdrecht, P. H. M.; Dhalenne, G.; Zakirov, A. R.

    2010-01-01

    The experimental temperature dependence (T = 2-300 K) of single crystal bulk and site susceptibilities of rare earth titanate pyrochlores R2Ti2O7 (R = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) is analyzed in the framework of crystal field theory and a mean field approximation. Analytical expressions for the s

  1. Synthesis and luminescence properties of rare earth ternary complexes consisting of Tb(Ⅲ),β-diketones and 1,10-phenanthroline (phen)

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In order to study the luminescent properties of ternary rare earth complexes with fl-diketone ligand,three new β-diketone ligands,1-phenyl-3-(p-phenylethynylphenyl)-1,3-propanedione(HPPP), 1-(2-thienyl)-3-(p-phenylethynylphenyl)-l,3-propanedione (HTPP) and 1-(2-furyl)-3-(p-phenylethynylphenyl)-1,3-propanedione (HFPP),were synthesized by Sonogashira coupling reaction and Claisen condensation.Three new ternary rare earth complexes,TbL3phen (L = PPP,TPP,or FPP),were synthesized by the reaction of rare earth chloride TbCl3,1,10-phenanthroline (phen) with HPPP,HTPP,or HFPP respectively,in alcohol solution.The compositions were characterized by means of elernental analysis,chemical analysis,and IR spectra.Luminescent properties of the three new complexes have been studied.The results show that the ternary Tb(Ⅲ) complexes only emit the weak fluorescence of the Tb(Ⅲ) ion,which reveals the triplet state energy of the ligands does not match well with the excited state vibrating energy of Tb3+ ion.

  2. 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)

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-02-15

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

  3. Chemical environment of rare earth ions in Ge28.125Ga6.25S65.625 glass-ceramics doped with Dy3+

    Science.gov (United States)

    Wang, Rongping; Yan, Kunlun; Zhang, Mingjie; Shen, Xiang; Dai, Shixun; Yang, Xinyu; Yang, Zhiyong; Yang, Anping; Zhang, Bin; Luther-Davies, Barry

    2015-10-01

    We have annealed Ge28.125Ga6.25S65.625 glasses doped with 0.5% Dy to create glass-ceramics in order to examine the local chemical environment of the rare earth ions (REI). More than 12 times enhancement of the emission at 2.9 and 3.5 μm was achieved in glass-ceramics produced using prolonged annealing time. Elemental mapping showed clear evidence that Ga2S3 crystalline grains with a size of 50 nm were dispersed in a Ge-S glass matrix in the glass-ceramics, and the REI could only be found near the Ga2S3 crystalline grains. From the unchanged lineshape of the emissions at 2.9 and 3.5 μm and lack of splitting of the absorption peaks, we concluded that the REI were bonded to Ga on the surface of the Ga2S3 crystals.

  4. Enhanced luminescence of rare-earth complexes Tb 1- xEu x( m-NBA) 3Phen in ZnS

    Science.gov (United States)

    Lv, Yuguang; Zhang, Jingchang; Cao, Weiliang; Song, Lin; Xu, Zheng

    2008-07-01

    Rare-earth ternary complexes Tb 1- xEu x( m-NBA) 3Phen ( X = 1, 0.25, 0.5, 0.75, 1.0) were synthesized and characterized by IR, DTA-TG, UV, fluorescent spectra and elemental analysis. It was found that luminescence of Eu 3+ complex was enhanced by doped with Tb 3+. It is proved by TG curve that the complexes are stable, ranging from ambient temperature to 360 °C in air. The organic-inorganic combined structural device was fabricated, and the electroluminescence intensity of the combined structural device was improved compared with the device of the purely organic components.

  5. Enhanced luminescence of rare-earth complexes Tb(1-x)Eu(x)(m-NBA)3Phen in ZnS.

    Science.gov (United States)

    Lv, Yuguang; Zhang, Jingchang; Cao, Weiliang; Song, Lin; Xu, Zheng

    2008-07-01

    Rare-earth ternary complexes Tb(1-x)Eu(x)(m-NBA)(3)Phen (X=1, 0.25, 0.5, 0.75, 1.0) were synthesized and characterized by IR, DTA-TG, UV, fluorescent spectra and elemental analysis. It was found that luminescence of Eu(3+) complex was enhanced by doped with Tb(3+). It is proved by TG curve that the complexes are stable, ranging from ambient temperature to 360 degrees C in air. The organic-inorganic combined structural device was fabricated, and the electroluminescence intensity of the combined structural device was improved compared with the device of the purely organic components.

  6. Note: Portable rare-earth element analyzer using pyroelectric crystal

    Energy Technology Data Exchange (ETDEWEB)

    Imashuku, Susumu, E-mail: imashuku.susumu.2m@kyoto-u.ac.jp; Fuyuno, Naoto; Hanasaki, Kohei; Kawai, Jun [Department of Materials Science and Engineering, Kyoto University, Sakyo, Kyoto 606-8501 (Japan)

    2013-12-15

    We report a portable rare-earth element analyzer with a palm-top size chamber including the electron source of a pyroelectric crystal and the sample stage utilizing cathodoluminescence (CL) phenomenon. The portable rare-earth element analyzer utilizing CL phenomenon is the smallest reported so far. The portable rare-earth element analyzer detected the rare-earth elements Dy, Tb, Er, and Sm of ppm order in zircon, which were not detected by scanning electron microscopy-energy dispersive X-ray spectroscopy analysis. We also performed an elemental mapping of rare-earth elements by capturing a CL image using CCD camera.

  7. Structural magnetic and magnetostrictive properties of Tb{sub 0.3}Dy{sub 0.7−x}Nd{sub x}Fe{sub 1.93} [x = 0, 0.05, 0.1, 0.15 and 0.2] compounds

    Energy Technology Data Exchange (ETDEWEB)

    Narayana Jammalamadaka, S., E-mail: surya@iith.ac.in [Advanced Magnetic Materials Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Magnetic Materials and Device Physics Laboratory, Department of Physics, Indian Institute of Technology Hyderabad, Hyderabad 502205 (India); Markandeyulu, G. [Advanced Magnetic Materials Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Balasubramaniam, Krishnan [Centre for Non Destructive Evaluation, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Arout Chelvane, J. [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India)

    2015-03-05

    Highlights: • Easy magnetization direction (EMD) for x = 0.2 compound it is towards 〈1 1 0〉. • Structural distortion from rhombohedral to orthorhombic from x = 0 to x = 0.2. • Tb{sub 0.3}Dy{sub 0.6}Nd{sub 0.1}Fe{sub 1.93} has a large magnetostriction and a low anisotropy. - Abstract: We report on the results pertinent to structural, magnetic, magnetostrictive studies of the Tb{sub 0.3}Dy{sub 0.7−x}Nd{sub x}Fe{sub 1.93} [x = 0, 0.05, 0.1, 0.15 and 0.2] compounds. From the evidenced magnetization and magnetostriction results, the crucial finding that we emphasize is that the realization of minimum anisotropy for the compound with the composition x = 0.1. From the X-ray diffraction on magnetically aligned samples, (4 4 0) peak splitting analysis and Mössbauer studies, we ascertain that the easy magnetization direction (EMD) for x = 0.2 compound it is towards 〈1 1 0〉. Above results also affirmed that indeed there exists transformation of the structural distortion from rhombohedral to orthorhombic from x = 0 to x = 0.2. The Laves phase compound Tb{sub 0.3}Dy{sub 0.6}Nd{sub 0.1}Fe{sub 1.93} with a large magnetostriction (λ{sub 111} ≈ 1270 × 10{sup −6}) and a low anisotropy may be a potential candidate for magnetostriction applications.

  8. A Novel Synthesis of Alkaline Earth Silicate Phosphor Sr3MgSi2O8:Eu2+,Dy3+

    Institute of Scientific and Technical Information of China (English)

    PAN,Wen; NING,Gui-Ling; WANG,Jing-Hui; LIN,Yuan

    2007-01-01

    A novel method for synthesizing long afterglow silicate phosphor Sr3MgSi2O8:Eu2+,Dy3+ using TEOS and inorganic powders as reactants was reported. Acetic acid as a catalyzer controlled the hydrolysis of TEOS by adjusting pH value of the system. The morphologies of precursor were characterized by transmission electron microscope(TEM). The structure and optical properties of the phosphor powders were systematically investigated by means of X-ray diffraction and spectrofluorometry. TEM images have reflected the core-shell structure and quasi-spherical morphology of the precursor particles. It was found that the single-phase Sr3MgSi2O8 crystalline structures were obtained at 1050 and 1250 ℃ for the samples prepared with the nano-coating method and the solid state reaction,respectively. The emission intensities of the phosphors prepared by the present method were higher than those by the conventional process. Also, the afterglow characteristic was better than that prepared by solid-state reaction in the comparable condition.

  9. Synthesis, structural, thermal and optical studies of rare earth coordinated complex: Tb(Sal){sub 3}Phen

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Gagandeep; Dwivedi, Y. [Laser and Spectroscopy Laboratory, Department of Physics, Banaras Hindu University, Varanasi 221005 (India); Rai, S.B., E-mail: sbrai49@yahoo.co.in [Laser and Spectroscopy Laboratory, Department of Physics, Banaras Hindu University, Varanasi 221005 (India)

    2011-11-01

    Highlights: {yields} RE coordinated complex of Tb(Sal){sub 3}Phen in crystalline phases were synthesized. {yields} Enhancement in luminescence of Tb{sup 3+} was observed in complex on 355 nm excitation. {yields} Fluorescence enhancement is due to the efficient energy transfer from Sal to Tb{sup 3+}. {yields} An observed increase in lifetime of Tb{sup 3+} is due to encapsulation in Sal/Phen network. {yields} The present system is a deserving candidate for LSC when coupled with solar cells. - Abstract: Complexes of salicylic acid (Sal) and 1,10-phenanthroline (Phen) were synthesized coordinated with terbium ion (Tb{sup 3+}) in crystalline phases. The structural characterizations of the lanthanide complex were made using FT-IR, NMR ({sup 1}H and {sup 13}C) and XRD techniques. These measurements confirm the formation of Tb(Sal){sub 3}Phen complex structure. The thermal aspects of the complex were examined using DTA and TGA techniques. An enhancement in luminescence intensity of Tb{sup 3+} ion bands were observed in Tb(Sal){sub 3}Phen complex as compared to TbCl{sub 3} crystals on 355 nm laser excitation. Enhancement is reported due to the efficient energy transfer process from Sal to Tb{sup 3+} ions. This is also confirmed by the time resolved photoluminescence spectroscopy with increase in lifetime of Tb{sup 3+} ions due to encapsulation in Sal/Phen network. Our system in itself can be a deserving candidate for luminescent solar collector material when coupled with solar cells.

  10. Rare Earth Chalcogels NaLnSnS4 (Ln = Y, Gd, Tb) for Selective Adsorption of Volatile Hydrocarbons and Gases

    KAUST Repository

    Edhaim, Fatimah

    2017-06-28

    The synthesis and characterization of the rare earth chalcogenide aerogels NaYSnS4, NaGdSnS4, and NaTbSnS4 is reported. Rare earth metal ions like Y3+, Gd3+, and Tb3+ react with the chalcogenide clusters [SnS4]4– in aqueous formamide solution forming extended polymeric networks by gelation. Aerogels obtained after supercritical drying have BET surface areas of 649 m2·g–1 (NaYSnS4), 479 m2·g–1 (NaGdSnS4), and 354 m2·g–1 (NaTbSnS4). Electron microscopy and physisorption studies reveal that the new materials have pores in the macro (above 50 nm) and meso (2–50 nm) regions. These aerogels show higher adsorption of toluene vapor over cyclohexane vapor and CO2 over CH4 or H2. The notable adsorption capacity for toluene (NaYSnS4: 1108 mg·g–1; NaGdSnS4: 921 mg·g–1; and NaTbSnS4: 645 mg·g–1) and high selectivity for gases (CO2/H2: 172 and CO2/CH4: 50 for NaYSnS4, CO2/H2: 155 and CO2/CH4: 37 for NaGdSnS4, and CO2/H2: 75 and CO2/CH4: 28 for NaTbSnS4) indicate potential future use of chalcogels in adsorption-based gas or hydrocarbon separation processes.

  11. Large magnetocaloric effect in Ln{sub 0.5}Ca{sub 0.5}MnO{sub 3} (Ln=Gd, DY) compounds: Conseqence of magnetic precursor effect of rare earth ions

    Energy Technology Data Exchange (ETDEWEB)

    Das, Kalipada, E-mail: kalipada.das@saha.ac.in; Paramanik, Tapas; Das, I.

    2015-01-15

    Magnetic, specific heat and magnetocaloric studies have been performed on rare earth calcium manganites; Ln{sub 0.5}Ca{sub 0.5}MnO{sub 3} (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 Gd{sub 0.5}Ca{sub 0.5}MnO{sub 3}, the isothermal magnetic entropy change (−ΔS) at 4 K, obtained for 7 T magnetic field, is as high as 22.8 J/kg K. On the other hand, −ΔS is 8.5 J/kg K for Dy{sub 0.5}Ca{sub 0.5}MnO{sub 3}. The large value of magnetic entropy change at the cryogenic temperature range for these compounds is interesting from application point of view. - Highlights: • No long range magnetic ordering of Gd{sub 0.5}Ca{sub 0.5}MnO{sub 3} and Dy{sub 0.5}Ca{sub 0.5}MnO{sub 3} has been observed in magnetization measurement down to T=2 K still these compounds show large magnetocaloric effect. • Specific heat of the compounds in absence of magnetic field increases at low temperature (down to 3 K). • Results are analyzed considering magnetic precursor effect of rare earth ions (Gd and Dy ions)

  12. TB Terms

    Science.gov (United States)

    ... Spanish) Recommend on Facebook Tweet Share Compartir TB disease – an illness in which TB bacteria are multiplying and attacking ... GIT) and T-Spot ® . TB test. TB disease – an illness in which TB bacteria are multiplying and attacking ...

  13. Carbonato-bridged Ni(II)2Ln(III)2 (Ln(III) = Gd(III), Tb(III), Dy(III)) complexes generated by atmospheric CO2 fixation and their single-molecule-magnet behavior: [(μ4-CO3)2{Ni(II)(3-MeOsaltn)(MeOH or H2O)Ln(III)(NO3)}2]·solvent [3-MeOsaltn = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato].

    Science.gov (United States)

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

    2013-06-17

    Atmospheric CO2 fixation of [Ni(II)(3-MeOsaltn)(H2O)2]·2.5H2O [3-MeOsaltn = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato], Ln(III)(NO3)3·6H2O, and triethylamine occurred in methanol/acetone, giving a first series of carbonato-bridged Ni(II)2Ln(III)2 complexes [(μ4-CO3)2{Ni(II)(3-MeOsaltn)(MeOH)Ln(III)(NO3)}2] (1Gd, 1Tb, and 1Dy). When the reaction was carried out in acetonitrile/water, it gave a second series of complexes [(μ4-CO3)2{Ni(II)(3-MeOsaltn)(H2O)Ln(III)(NO3)}2]·2CH3CN·2H2O (2Gd, 2Tb, and 2Dy). For both series, each Ni(II)2Ln(III)2 structure can be described as two di-μ-phenoxo-bridged Ni(II)Ln(III) binuclear units bridged by two carbonato CO3(2-) units to form a carbonato-bridged (μ4-CO3)2{Ni(II)2Ln(III)2} structure. The high-spin Ni(II) ion has octahedral coordination geometry, and the Ln(III) ion is coordinated by O9 donor atoms from Ni(II)(3-MeOsaltn), bidentate NO3(-), and one and two oxygen atoms of two CO3(2-) ions. The NO3(-) ion for the first series roughly lie on Ln-O(methoxy) bonds and are tilted toward the outside, while for the second series, the two oxygen atoms roughly lie on one of the Ln-O(phenoxy) bonds due to the intramolecular hydrogen bond. The temperature-dependent magnetic susceptibilities indicated a ferromagnetic interaction between the Ni(II) and Ln(III) ions (Ln(III) = Gd(III), Tb(III), Dy(III)) for all of the complexes, with a distinctly different magnetic behavior between the two series in the lowest-temperature region due to the Ln(III)-Ln(III) magnetic interaction and/or different magnetic anisotropies of the Tb(III) or Dy(III) ion. Alternating-current susceptibility measurements under the 0 and 1000 Oe direct-current (dc) bias fields showed no magnetic relaxation for the Ni(II)2Gd(III)2 complexes but exhibited an out-of-phase signal for Ni(II)2Tb(III)2 and Ni(II)2Dy(III)2, indicative of slow relaxation of magnetization. The energy barriers, Δ/kB, for the spin flipping were estimated from the Arrhenius

  14. Effect of rapid quenching on the magnetism and magnetocaloric effect of equiatomic rare earth intermetallic compounds RNi (R = Gd, Tb and Ho)

    Science.gov (United States)

    Rajivgandhi, R.; Arout Chelvane, J.; Quezado, S.; Malik, S. K.; Nirmala, R.

    2017-07-01

    Magnetocaloric effect (MCE) in RNi (where R = Gd, Tb and Ho) compounds has been studied in their arc-melted and melt-spun forms. The compound GdNi has the orthorhombic CrB-type structure (Space group Cmcm, No. 63) and the compound HoNi has the orthorhombic FeB-type structure (Space group Pnma, No. 62) at room temperature regardless of their synthesis condition. However, arc-melted TbNi orders in a monoclinic structure (Space group P21/m, No. 11) and when it is rapidly quenched to a melt-spun form, it crystallizes in an orthorhombic structure (Space group Pnma, No. 62). The arc-melted GdNi, TbNi and HoNi compounds order ferromagnetically at ∼69 K, ∼67 K and ∼36 K (TC) respectively. While the melt-spun GdNi shows about 6 K increase in TC, the ordering temperature of TbNi remains nearly the same in both arc-melted and melt-spun forms. In contrast, a reduction in TC by about 8 K is observed in melt-spun HoNi, when compared to its arc-melted counterpart. Isothermal magnetic entropy change, ∆Sm, calculated from the field dependent magnetization data indicates an enhanced relative cooling power (RCP) for melt-spun GdNi for field changes of 20 kOe and 50 kOe. A lowered RCP value is observed in melt-spun TbNi and HoNi. These changes could have resulted from the competing shape anisotropy and the granular microstructure induced by the melt-spinning process. Tailoring the MCE of rare earth intermetallic compounds by suitably controlled synthesis techniques is certainly one of the directions to go forward in the search of giant magnetocaloric materials.

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

    Energy Technology Data Exchange (ETDEWEB)

    Nisius, D.; Janssens, R.V.F.; Crowell, B. [and others

    1995-08-01

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

  16. Multi-walled carbon nanotube-based ternary rare earth (Eu3+, Tb3+) hybrid materials with organically modified silica-oxygen bridge.

    Science.gov (United States)

    Li, Qiu-Ping; Yan, Bing

    2012-08-15

    A series of ternary rare earth (Eu(3+), Tb(3+)) complexes are covalently coated to the 3-aminopropyltriethoxysilane functionalized multi-walled carbon nanotube (MWCNT) by a simple in situ sol-gel method by the bifunctional silylated monomer TTA-Si and TAA-Si (TTA-Si and TAA-Si are 3-(triethoxysilyl)propylisocyanate (TEPIC) modified thenoyltrifluoroacetone (TTA) and trifluoroacetylacetone (TAA), respectively). The resulting materials are characterized by Fourier transform infrared spectra, scanning electronic microscope, transmission electron microscope, thermogravimetric analysis, ultraviolet visible diffused reflection measure, photoluminescence spectra, and X-ray diffraction. The photoluminesce measurements indicated that these hybrids exhibit characteristic red and green luminescence originating from the corresponding ternary rare earth ion (Eu(3+), Tb(3+)). The luminescence quenching effect of MWCNT networks have been successfully restrained by coating a relatively thicker silica-oxygen-based organic-inorganic complex. Furthermore, the fluorescence lifetimes and emission quantum efficiencies of Eu(3+) hybrid materials are also determined. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Binary phase diagrams of the rare earth metals with zinc: the Tb-Zn, Ho-Zn and Er-Zn systems

    Energy Technology Data Exchange (ETDEWEB)

    Saccone, A.; Cardinale, A.M.; Delfino, S.; Ferro, R. [Dipt. di Chimica e Chimica Industriale, Sezione di Chimica Inorganica e Metallurgia, Univ. di Genova, (Italy)

    2005-12-01

    The phase diagram of the Er-Zn system has been experimentally investigated over its whole composition range by using differential thermal analysis, X-ray diffraction, optical and scanning electron microscopy, and electron probe microanalysis. Seven intermetallic phases have been found and their crystal structure confirmed, namely ErZn, ErZn{sub 2}, ErZn{sub 3}, Er{sub 13}Zn{sub 58}, ErZn{sub 5}, Er{sub 2}Zn{sub 17}, and ErZn{sub 12}. Four eutectic reactions occur. A degenerate invariant effect has been found in the Zn-rich region. The results obtained in this investigation have been used, together with those of other previously studied rare earth-Zn systems, to predict the constitutional properties of the Tb-Zn and Ho-Zn systems, taking into account that the alloying behaviour of the different rare earths with the same element varies according to systematic patterns. The predicted phase diagrams of the Tb-Zn and Ho-Zn systems are compared with selected equilibria experimentally determined by analysing a few key compositions. (orig.)

  18. Structural and conductivity properties of Bi{sub 0.775}Ln{sub 0.225}O{sub 1.5} oxide conductors (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy) with rhombohedral Bi-Sr-O type

    Energy Technology Data Exchange (ETDEWEB)

    Drache, M.; Obbade, S.; Wignacourt, J.P.; Conflant, P. [USTL-ENSCL, Villeneuve d`Ascq (France). Lab. de Cristallochimie et Physicochimie du Solide

    1999-02-01

    This paper deals with structural and conductivity properties of the dimorphic Bi{sub 0.775}Ln{sub 0.225}O{sub 1.5} (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy) hexagonal structure layer phases with rhombohedral Bi-Sr-O type. The evolutions, versus Ln{sub VI}{sup 3+} radius, of cell parameters, thermal expansion coefficients, electrical properties (conductivity and activation energy), and structural characteristics determined from Rietveld powder structure refinements, suggest two different domains (La-Sm) and (Gd-Dy), with the intermediate Eu sample, thus possibly characterizing two kinds of ordering in the mixed cationic layer. The best conductivity properties obtained for Bi{sub 0.775}La{sub 0.225}O{sub 1.5} ({sigma}{sub 400{degree}C} = 10{sup {minus}3} S cm{sup {minus}1} with E{sub a} = 0.8 eV) are discussed and justified.

  19. The Study on the Interaction between Tm3+ and Tb3+ Rare Earth Ions in YVO4 Crystal

    Institute of Scientific and Technical Information of China (English)

    HUANG Lilei; HONG Zhi; ZHUANG Jian

    2001-01-01

    In this paper the measurement result of transmission spectrum of Tb,Tm∶YVO4 is presented. The intensity Ωt, the probabilities of radiating transition, non-radiating transition, the cross-relaxation and the lifetimes of Tm3+ ions at 3H4 and 3F4 levels are calculated. The results show that when the concentration of Tm3+ ions >1.2 at.-%, the fluorescent lifetime of upper level 3H4 is shorter than that of lower level 3F4 due to the interaction between Tm3+ and Tb3+ ions, thus the lasing self-termination at ~1.5 μm can be eliminated.

  20. Fiber-optic thermometer application of thermal radiation from rare-earth end-doped SiO{sub 2} fiber

    Energy Technology Data Exchange (ETDEWEB)

    Katsumata, Toru, E-mail: katsumat@toyo.jp; Morita, Kentaro; Komuro, Shuji; Aizawa, Hiroaki [Faculty of Science and Engineering, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-8585 (Japan)

    2014-08-15

    Visible light thermal radiation from SiO{sub 2} glass doped with Y, La, Ce, Pr, Nd, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu were studied for the fiber-optic thermometer application based on the temperature dependence of thermal radiation. Thermal radiations according to Planck's law of radiation are observed from the SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu at the temperature above 1100 K. Thermal radiations due to f-f transitions of rare-earth ions are observed from the SiO{sub 2} fibers doped with Nd, Dy, Ho, Er, Tm, and Yb at the temperature above 900 K. Peak intensities of thermal radiations from rare-earth doped SiO{sub 2} fibers increase sensitively with temperature. Thermal activation energies of thermal radiations by f-f transitions seen in Nd, Dy, Ho, Er, Tm, and Yb doped SiO{sub 2} fibers are smaller than those from SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu. Thermal radiation due to highly efficient f-f transitions in Nd, Dy, Ho, Er, Tm, and Yb ions emits more easily than usual thermal radiation process. Thermal radiations from rare-earth doped SiO{sub 2} are potentially applicable for the fiber-optic thermometry above 900 K.

  1. Transition metal (Cr{sup 3+}) and rare earth (Eu{sup 3+}, Dy{sup 3+}) ions used as a spectroscopic probe in compositional-dependent lead borate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Pisarski, W.A., E-mail: Wojciech.Pisarski@us.edu.p [University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice (Poland); Pisarska, J. [Silesian University of Technology, Department of Materials Science, Krasinskiego 8, 40-019 Katowice (Poland); Dominiak-Dzik, G.; Ryba-Romanowski, W. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okolna 2, 50-422 Wroclaw (Poland)

    2009-09-18

    Compositional-dependent lead borate glasses doped with transition metal and rare earth ions were studied using absorption and luminescence spectroscopy. The trivalent Cr{sup 3+}, Eu{sup 3+} and Dy{sup 3+} ions were used as a spectroscopic probe in glass samples with various PbO/B{sub 2}O{sub 3} ratios. Spectral analysis indicates that Cr{sup 3+} ions occupy intermediate field sites; the both sites coexist and emit from the {sup 4}T{sub 2} (low-field) and the {sup 2}E (high-field) states, respectively. The R and Y/B values due to {sup 5}D{sub 0}-{sup 7}F{sub 2}/{sup 5}D{sub 0}-{sup 7}F{sub 1} and {sup 4}F{sub 9/2}-{sup 6}H{sub 15/2}/{sup 4}F{sub 9/2}-{sup 6}H{sub 13/2} luminescence intensity ratios of Eu{sup 3+} and Dy{sup 3+} ions, respectively, increase with increasing heavy metal (PbO) content, suggesting higher asymmetry and more covalent bonding character between rare earth and oxygen ions.

  2. 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.

    Science.gov (United States)

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

    2012-10-01

    A new family of [2 × 2] tetranuclear 3d-4f heterometallic complexes have been synthesized. These are [Zn(2)Dy(2)L(2)(μ(3)-OH)(2)(μ(4)-OH)(dbm)(2)(MeOH)(2)](NO(3))·2H(2)O·MeOH (3), [Ni(2)Dy(2)L(2)(μ(3)-OH)(2)(μ(4)-OH)(dbm)(2)(MeOH)(2)](NO(3))·MeOH (4), [Ni(2)La(2)L(2)(μ(3)-OH)(2)(μ(4)-OH)(dbm)(2)(MeOH)(2)](ClO(4))·H(2)O·2MeOH (5), [Ni(2)Tb(2)L(2)(μ(3)-OH)(2)(μ(4)-OH)(dbm)(2) (MeOH)(2)](NO(3))·MeOH (6), and [Ni(2)Gd(2)L(2)(μ(3)-OH)(2)(μ(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 μ(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.

  3. Magnetic Ground States of the Rare-Earth Tripod Kagome Lattice Mg2 RE3 Sb3 O14 (RE =Gd ,Dy ,Er )

    Science.gov (United States)

    Dun, Z. L.; Trinh, J.; Li, K.; Lee, M.; Chen, K. W.; Baumbach, R.; Hu, Y. F.; Wang, Y. X.; Choi, E. S.; Shastry, B. S.; Ramirez, A. P.; Zhou, H. D.

    2016-04-01

    We present the structural and magnetic properties of a new compound family, Mg2 RE3 Sb3 O14 (RE =Gd ,Dy ,Er ), with a hitherto unstudied frustrating lattice, the "tripod kagome" structure. Susceptibility (ac, dc) and specific heat exhibit features that are understood within a simple Luttinger-Tisza-type theory. For RE =Gd , we found long-ranged order (LRO) at 1.65 K, which is consistent with a 120° structure, demonstrating the importance of diople interactions for this 2D Heisenberg system. For RE =Dy , LRO at 0.37 K is related to the "kagome spin ice" physics for a 2D system. This result shows that the tripod kagome structure accelerates the transition to LRO predicted for the related pyrochlore systems. For RE =Er , two transitions, at 80 mK and 2.1 K are observed, suggesting the importance of quantum fluctuations for this putative X Y system.

  4. Influence of rare-earth additives (La, Sm and Dy on the microstructure and dielectric properties of doped BaTiO3 ceramics

    Directory of Open Access Journals (Sweden)

    Paunović Vesna

    2010-01-01

    Full Text Available A series of La/Mn, Sm/Mn and Dy/Mn codoped BaTiO3 samples were prepared by the conventional solid state procedure with dopant concentrations ranging from 0.1 up to 2.0 at%. The specimens were sintered at 1320°C and 1350°C in an air atmosphere for two hours. The low doped samples demonstrated a mainly uniform and homogeneous microstructure with average grain sizes ranging from 0.3 μm to 5.0 μm. The appearance of secondary abnormal grains in the fine grain matrix and core-shell structure were observed in highly doped La/BaTiO3 and Dy/BaTiO3 sintered at 1350°C. The low doped samples, sintered at 1350°C, display a high value of dielectric permittivity at room temperature, 6800 for Sm/BaTiO3, 5900 for Dy/BaTiO3 and 3100 for La/BaTiO3. A nearly flat permittivity-response was obtained in specimens with 2.0 at% additive content. Using a modified Curie-Weiss law the Curie-like constant C⁄ and a critical exponent γ were calculated. The obtained values of γ pointed out the diffuse phase transformation in heavily doped BaTiO3 samples.

  5. Silver doping of silica-hafnia waveguides containing Tb3+/Yb3+ rare earths for downconversion in PV solar cells

    Science.gov (United States)

    Enrichi, F.; Armellini, C.; Battaglin, G.; Belluomo, F.; Belmokhtar, S.; Bouajaj, A.; Cattaruzza, E.; Ferrari, M.; Gonella, F.; Lukowiak, A.; Mardegan, M.; Polizzi, S.; Pontoglio, E.; Righini, G. C.; Sada, C.; Trave, E.; Zur, L.

    2016-10-01

    The aim of this paper is to study the possibility to obtain an efficient downconverting waveguide which combines the quantum cutting properties of Tb3+/Yb3+ codoped materials with the optical sensitizing effects provided by silver doping. The preparation of 70SiO2-30HfO2 glass and glass-ceramic waveguides by sol-gel route, followed by Ag doping by immersion in molten salt bath is reported. The films were subsequently annealed in air to induce the migration and/or aggregation of the metal ions. Results of compositional and optical characterization are given, providing evidence for the successful introduction of Ag in the films, while the photoluminescence emission is strongly dependent on the annealing conditions. These films could find potential applications as downshifting layers to increase the efficiency of PV solar cells.

  6. 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).

    Science.gov (United States)

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

    2013-05-20

    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 χ(M)T and M

  7. Effect of alkaline earth oxides on the physical and spectroscopic properties of Dy3+- doped Li2O-B2O3 glasses for white emitting material application

    Science.gov (United States)

    Shamshad, L.; Rooh, G.; Kirdsiri, K.; Srisittipokakun, N.; Damdee, B.; Kim, H. J.; Kaewkhao, J.

    2017-02-01

    Li2O-MO-B2O3:0.5Dy2O3 glasses mixed with four different alkaline earth modifier oxides MgO, CaO, SrO and BaO were synthesized by melt quench technique. Their physical properties like density, molar volume and refractive index were measured at room temperature and the effect of alkaline earth modifier oxides were studied. Also, optical absorption and photoluminescence spectra of these glasses have been acquired at room temperature. The Judd-Ofelt theory was effectively used to characterize these spectra and spectral intensities (ƒcal), Judd-Ofelt intensity parameters (Ω2, Ω4 and Ω6) and certain radiative properties have been determined. Radiative life-times (τR), branching ratios (βcal), and emission cross-sections (σp) and optical gain parameters (σp × τR) were calculated from the Judd-Ofelt intensity parameters and the variation in these parameters with the variation of glass matrix are discussed. Yellow/Blue (Y/B) ratio and chromacity color coordinates (x,y) are calculated from the emission spectra which indicates the white light generation from all the investigated samples. The correlated color temperature (CCT) for the studied glasses is found to be 4418 K. The fluorescence decay time (τexp) of the 4F9/2 level of Dy3+ has been measured from the decay profiles and compared with calculated lifetimes (τcal). Among all the studied glass matrices, the glass containing BaO exhibits high value of branching ratio, large emission cross-section and high optical gain parameter for 6F9/2 → 6H13 at 575 nm. The results indicates the suitability of all the studied glasses for laser action and white light generation.

  8. Magnetic Ground States of the Rare-Earth Tripod Kagome Lattice Mg_{2}RE_{3}Sb_{3}O_{14} (RE=Gd,Dy,Er).

    Science.gov (United States)

    Dun, Z L; Trinh, J; Li, K; Lee, M; Chen, K W; Baumbach, R; Hu, Y F; Wang, Y X; Choi, E S; Shastry, B S; Ramirez, A P; Zhou, H D

    2016-04-15

    We present the structural and magnetic properties of a new compound family, Mg_{2}RE_{3}Sb_{3}O_{14} (RE=Gd,Dy,Er), with a hitherto unstudied frustrating lattice, the "tripod kagome" structure. Susceptibility (ac, dc) and specific heat exhibit features that are understood within a simple Luttinger-Tisza-type theory. For RE=Gd, we found long-ranged order (LRO) at 1.65 K, which is consistent with a 120° structure, demonstrating the importance of diople interactions for this 2D Heisenberg system. For RE=Dy, LRO at 0.37 K is related to the "kagome spin ice" physics for a 2D system. This result shows that the tripod kagome structure accelerates the transition to LRO predicted for the related pyrochlore systems. For RE=Er, two transitions, at 80 mK and 2.1 K are observed, suggesting the importance of quantum fluctuations for this putative XY system.

  9. Grain boundary engineering in sintered Nd-Fe-B permanent magnets for efficient utilization of heavy rare earth elements

    Energy Technology Data Exchange (ETDEWEB)

    Loewe, Konrad

    2016-10-18

    The first part of the thesis investigates the diffusion of rare-earth (RE) elements in commercial sintered Nd-Fe-B based permanent magnets. A strong temperature dependence of the diffusion distance and resulting change in magnetic properties were found. A maximum increase in coercivity of ∼+350 kA/m using a Dy diffusion source occurred at the optimum annealing temperature of 900 C. After annealing for 6 h at this temperature, a Dy diffusion distance of about 4 mm has been observed with a scanning Hall probe. Consequently, the maximum thickness of grain boundary diffusion processed magnets with homogeneous properties is also only a few mm. The microstructural changes in the magnets after diffusion were investigated by electron microscopy coupled with electron probe microanalysis. It was found that the diffusion of Dy into sintered Nd-Fe-B permanent magnets occurs along the grain boundary phases, which is in accordance with previous studies. A partial melting of the Nd-Fe-B grains during the annealing process lead to the formation of so - called (Nd,Dy)-Fe-B shells at the outer part of the grains. These shells are μm thick at the immediate surface of the magnet and become thinner with increasing diffusion distance towards the center of the bulk. With scanning transmission electron microscopy coupled with electron probe analysis a Dy content of about 1 at.% was found in a shell located about 1.5 mm away from the surface of the magnet. The evaluation of diffusion speeds of Dy and other RE (Tb, Ce, Gd) in Nd-Fe-B magnets showed that Tb diffuses significantly faster than Dy, and Ce slightly slower than Dy, which is attributed to differences in the respective phase diagrams. The addition of Gd to the grain boundaries has an adverse effect on coercivity. Exemplary of the heavy rare earth element Tb, the nano - scale elemental distribution around the grain boundaries after the diffusion process was visualized with high resolution scanning transmission electron microscopy

  10. Investigation of Kpong carbonatite as a potential source for rare earth elements (REEs) using instrumental neutron activation analysis (INAA)

    Energy Technology Data Exchange (ETDEWEB)

    Hayford, M.S.; Akiti, T.T.; Serfor-Armah, Y.; Dampare, S.B. [Ghana Univ., Accra (Ghana). School of Nuclear and Allied Sciences; Ghana Atomic Energy Commission (GAEC), Legon-Accra (Ghana). Nuclear Chemistry and Environmental Research Centre

    2013-07-01

    Instrumental neutron activation analysis (INAA) was used to investigate REEs in carbonatite from Kpong southeastern, Ghana. Total rare earth element (TREEs) obtain were in the range of 540 mg/kg to 705 mg/kg. The total number of rare earth elements (REEs) determined by INAA in the carbonatite rocks from Kpong were 11, namely; La, Ce, Nd, Sm, Eu, Tb, Dy, Ho, Tm, Yb, Lu. The INAA results from the carbonatite show a high enrichment of light rare earth elements (LREEs) deposits, marking the Kpong carbonatite as a potential REE source. (orig.)

  11. Preparation, crystal structure and optical spectroscopy of the rare earth complexes (RE 3+=Sm, Eu, Gd and Tb) with 2-thiopheneacetate anion

    Science.gov (United States)

    Teotonio, Ercules E. S.; Brito, Hermi F.; Felinto, Maria Cláudia F. C.; Thompson, Larry C.; Young, Victor G.; Malta, Oscar L.

    2005-09-01

    Rare earth complexes with the formulae Sm(TPAC) 3·3H 2O, Eu 2(TPAC) 6·5.25H 2O and RE(TPAC) 3·3.5H 2O (where RE=Gd and Tb), and TPAC=2-thiopheneacetate) have been synthesized and characterized by complexometric titration, elemental analyses, infrared spectroscopy, and X-ray crystallography. Infrared data suggested the presence of both bridging and chelating TPAC anions. The crystal structure of the [Eu 2(TPAC) 6·(H 2O) 3]·2.25H 2O complex in the solid state, determined by X-ray diffraction, revealed that it crystallizes in the orthorhombic crystal system (space group Aba2), with two crystallographically independent Eu 3+ centers (Eu1 and Eu2). These europium centers are held together by one bidentate bridging and two tridentate bridging carboxylate groups. The existence of two Eu 3+ centers was also supported by the emission spectrum. The luminescence properties of the RE-TPAC complexes were investigated by measuring the excitation and emission spectra, and the intramolecular ligand-to-rare earth energy transfer mechanisms were discussed. The emission spectra of the Eu 3+ and Tb 3+ ions displayed only narrow bands arising from 5D 0→ 7F 0 and 5D 0→ 7F 0-4 transitions, respectively, indicating an efficient luminescence sensitization of these ions by the TPAC 'antenna'. On the other hand, the emission spectrum of the Sm 3+-complex displayed a broad band from the phosphorescence of the TPAC ligand which overlapped the 4f 5-intraconfigurational transitions. The theoretical intensity parameters Ωλ ( λ=2 and 4), maximum splitting of the 7F 1 state (Δ E) and the ratio between the 5D 0→ 7F 0 and 5D 0→ 7F 2 transition intensities ( R02) were calculated based on the X-ray crystalline structure for the Eu 3+-complex, and a comparison with experimental data were made. The emission quantum efficiency ( η) of the D5 emitting level of the Eu 3+ ion was also determined.

  12. Polytypic phase formation in DyAl3 by rapid solidification

    Science.gov (United States)

    Xu, Yan; Altounian, Z.; Muir, W. B.

    1991-01-01

    Amorphous ribbons of AlxDy100-x, 93≳x≳85, were obtained by melt spinning. During crystallization, in addition to Al, four different metastable crystalline phases of DyAl3 were observed. These phases are, in order of appearance, the high-pressure face-centered cubic phase, γ-DyAl3 and three polytypic rhombohedral phases, β-DyAl3, β'-DyAl3, and α'-DyAl3. It is the first time that the β' phase in rare-earth trialuminides and the α' phase in Dy-Al alloy system have been observed. It is shown that all these phases are associated with the polytypic packing of the hexagonal DyAl3 atomic layers. The relative stability of the phases is found to be related to the hexagonal to cubic stacking ratio in the structure.

  13. Particle temperature measurements in closed chamber detonations using thermoluminescence from Li{sub 2}B{sub 4}O{sub 7}:Ag,Cu, MgB{sub 4}O{sub 7}:Dy,Li and CaSO{sub 4}:Ce,Tb

    Energy Technology Data Exchange (ETDEWEB)

    Yukihara, E.G., E-mail: eduardo.yukihara@okstate.edu [Physics Department, Oklahoma State University, 145 Physical Sciences, Stillwater, OK 74078 (United States); Coleman, A.C.; Bastani, S.; Gustafson, T. [Physics Department, Oklahoma State University, 145 Physical Sciences, Stillwater, OK 74078 (United States); Talghader, J.J. [Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455 (United States); Daniels, A.; Stamatis, D.; Lightstone, J. M; Milby, C.; Svingala, F.R. [Naval Surface Warfare Center, Indian Head Explosive Ordnance Disposal Technology Division (NSWC IHEODTD), Indian Head, MD 20640 (United States)

    2015-09-15

    The present work describes the procedures and results from the first temperature measurements in closed chamber detonations obtained using the thermoluminescence (TL) of particles specifically developed for temperature sensing. Li{sub 2}B{sub 4}O{sub 7}:Ag,Cu (LBO), MgB{sub 4}O{sub 7}:Dy,Li (MBO) and CaSO{sub 4}:Ce,Tb (CSO) were tested separately in a total of 12 independent detonations using a closed detonation chamber at the Naval Surface Warfare Center, Indian Head Explosive Ordnance Disposal Technology Division (NSWC IHEODTD). Detonations were carried out using two different explosives: a high temperature plastic bonded explosive (HPBX) and a low temperature plastic bonded explosive (LPBX). The LPBX and HPBX charges produced temperatures experienced by the TL particles to be between ~550–670 K and ~700–780 K, respectively, depending on the shot. The measured temperatures were reproducible and typically higher than the thermocouple temperatures. These tests demonstrate the survivability of the TL materials and the ability to obtain temperature estimates in realistic conditions, indicating that TL may represent a reliable way of estimating the temperature experienced by free-flowing particles inside an opaque post-detonation fireball. - Highlights: • TL materials were tested in closed chamber detonations. • Temperatures experienced by the particles were ~550–670 K and ~700–780 K. • TL temperatures were reproducible and higher than thermocouple measurements. • Tests demonstrate TL material survival and ability to obtain temperature estimates.

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

    Science.gov (United States)

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

    2016-07-01

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

  15. Facile synthesis, structural and spectroscopic properties of GdF{sub 3}:Ce{sup 3+}, Ln{sup 3+} (Ln{sup 3+}=Sm{sup 3+}, Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) nanocrystals with bright multicolor luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Grzyb, Tomasz; Runowski, Marcin; Lis, Stefan, E-mail: blis@amu.edu.pl

    2014-10-15

    Hexagonal gadolinium fluorides doped with Ce{sup 3+} ions and co-doped with Sm{sup 3+}, Eu{sup 3+}, Tb{sup 3+} or Dy{sup 3+} were successfully synthesized via a simple co-precipitation approach, in the presence of glycerin as a capping agent. These fluorides, as solids or in aqueous solutions, showed intense, multicolored luminescence depending on the lanthanide ions used. The structures of the products were confirmed by powder X-ray diffraction (XRD). The morphologies of the synthesized nanophosphors were examined using transmission electron microscopy (TEM). The TEM results showed that the crystallites had shapes that varied with the dopant ion used. The spectroscopic properties: excitation spectra, emission spectra and luminescence decays were recorded and studied in detail. Bright luminescences from all of the products were triggered by effective energy transfer between the ions embedded in their structures. The mechanism for this phenomenon was also proposed. All of the synthesized products formed stable aqueous colloids, exhibiting brightly multicolored luminescence under UV light irradiation. - Highlights: • Hexagonal GdF{sub 3}:Ce{sup 3+}, Ln{sup 3+} nanocrystals were synthesized by a co-precipitation method. • Nanocrystals formed stable water colloids. • Multicolor luminescence under UV light was observed. • Energy transfer mechanism between Gd{sup 3+}, Ce{sup 3+} and Ln{sup 3+} ions was proposed.

  16. Tuberculosis (TB)

    Science.gov (United States)

    ... Addressing This Critical Topic? NIAID supports a comprehensive portfolio of research covering basic, translational and clinical studies ... candidate drugs, and evaluate novel TB drugs and optimal drug combinations in preclinical and clinical studies. Read ...

  17. Static magnetic susceptibility, crystal field and exchange interactions in rare earth titanate pyrochlores.

    Science.gov (United States)

    Malkin, B Z; Lummen, T T A; van Loosdrecht, P H M; Dhalenne, G; Zakirov, A R

    2010-07-14

    The experimental temperature dependence (T = 2-300 K) of single crystal bulk and site susceptibilities of rare earth titanate pyrochlores R(2)Ti(2)O(7) (R = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) is analyzed in the framework of crystal field theory and a mean field approximation. Analytical expressions for the site and bulk susceptibilities of the pyrochlore lattice are derived taking into account long range dipole-dipole interactions and anisotropic exchange interactions between the nearest neighbor rare earth ions. The sets of crystal field parameters and anisotropic exchange coupling constants have been determined and their variations along the lanthanide series are discussed.

  18. Electron microscopy of microwave-synthesized rare-earth chromites

    OpenAIRE

    Schmidt, Rainer; Prado-Gonjal, Jesus; Avila, David; Amador, Ulises; Moran, Emilio

    2014-01-01

    The perovskite rare-earth (RE) chromite series (RE)CrO3 (RE = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Y, Ho, Er, Tm, Yb, Lu) has been synthesized in our laboratory using microwave techniques. In this work we will demonstrate how X-ray diffraction (XRD), Rietveld refinement of XRD pattern and complementary High Resolution Transmission Electron Microscopy (HRTEM) were used to confirm that the desired crystal structure had been formed. Field-emission scanning electron microscopy (FE-SEM) gave clear ...

  19. Magnetic structures of R{sub 3}Cu{sub 4}Sn{sub 4} (R=Tb-Er)

    Energy Technology Data Exchange (ETDEWEB)

    Wawrzynska, E.; Hernandez-Velasco, J.; Penc, B.; Szytula, A

    2004-07-15

    Neutron powder diffraction studies of the R{sub 3}Cu{sub 4}Sn{sub 4} (R=Tb, Dy, Ho, Er) intermetallic compounds with the orthorhombic Gd{sub 3}Cu{sub 4}Ge{sub 4}-type crystal structure indicate the existence of different magnetic structures. Rare earth atoms occupy two nonequivalent 2d and 4e sublattices. For R=Tb and Dy the magnetic structures below the Neel temperatures equal to 17.5 and 15 K, respectively, are described by the propagation vectors k=(0,0,((1)/(2))+{delta}). In these compounds both rare earth sublattices order and do not change up to the Neel temperatures. For R=Ho the magnetic structure is more complicated. There are two vectors; one of them is k=(0,(1/2),0) whereas the second one changes with temperature. For the Er compound there is the propagation vector k=(1/2),(1/2),0) which describes the magnetic ordering in the 2d sublattice and at low temperatures it is accompanied with the propagation vector k=(0,0,{delta}) describing the ordering in the 4e sublattice.

  20. Preparation and Characterization of Yttrium Hydroxide and Oxide Doped with Rare Earth Ions (Eu3+, Tb3+) Nano One-dimensional

    Science.gov (United States)

    Giang, Lam Thi Kieu; Anh, Tran Kim; Marciniak, Lukasz; Hreniak, Dariusz; Strek, Wieslaw; Lojkowski, Witold; Minh, Le Quoc

    The one-dimensional (1D) crystalline nanostructures of Y(OH)3:Eu/Tb have been synthesized using softemplate method at temperature range of 180 - 200 °C for 24 h. The studies by Field Emission Scanning Electron Microscopy (FESEM) have been determined that the outer and interior hollow diameter of Y(OH)3:Eu/Tb nanotubes was obtained range from 150 to 500 nm and 100 to 300 nm, respectively and of the length up to several micrometers, respectively. The Y2O3:Eu/Tb nanorod/tubes have been obtained from Y(OH)3:Eu/Tb counterparts by crucial annealing. The Xray diffraction (XRD) patterns indicated that the Y(OH)3:Eu/Tb and Y2O3:Eu/Tb nanorods and nanotubes obtained has hexagonal and cubic phase with high crystaline. The luminescence and excitation properties of Y(OH)3:Eu/Tb and Y2O3:Eu/Tb nanorods and nanotubes were investigated in details. It found that crystal form and nanomorphology of Y(OH)3 and Y2O3 have played a great role on the emission properties of the doped Eu3+ ions.

  1. Structure and spectroscopy of rare earth – Doped lead phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Pisarski, Wojciech A., E-mail: wojciech.pisarski@us.edu.pl [University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice (Poland); Żur, Lidia [University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice (Poland); Goryczka, Tomasz [University of Silesia, Institute of Materials Science, Bankowa 12, 40-007 Katowice (Poland); Sołtys, Marta; Pisarska, Joanna [University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice (Poland)

    2014-02-25

    Highlights: • Lead phosphate glasses doped with rare earth ions were prepared. • The local structure was examined using X-ray diffraction and spectroscopic methods. • Different structural phosphate groups are present in lead phosphate glasses. • The electron–phonon coupling strength and phonon energy of the glass host was determined. • Several observed emission bands are due to 4f–4f electronic transitions of rare earth ions. -- Abstract: Lead–gallium phosphate glasses doped with rare the earth ions (Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+}, Er{sup 3+}) were synthesized. The structure of obtained glasses was examined by means of use: X-ray diffraction (XRD), nuclear magnetic resonance ({sup 207}Pb and {sup 31}P NMR), fourier transform infrared (FT-IR) and Raman spectroscopy. In contrast to fully amorphous Ln-doped samples (Ln = Eu, Dy, Tb), in Er-doped sample the GaPO{sub 4} crystalline phase was identified. It was found from the NMR, FT-IR and Raman spectroscopic techniques that, different structural phosphate groups were present in lead phosphate glasses. Based on absorption measurements, the UV–VIS cut-off wavelength for lead phosphate glass was determined and its value is close to 305 nm. Excitation and emission spectra of rare earths were also detected. From excitation spectra of Eu{sup 3+} the electron–phonon coupling strength and phonon energy of the glass host were determined. Due to 4f{sup 6}–4f{sup 6} (Eu{sup 3+}), 4f{sup 8}–4f{sup 8} (Tb{sup 3+}), 4f{sup 9}–4f{sup 9} (Dy{sup 3+}) and 4f{sup 11}–4f{sup 11} (Er{sup 3+}) electronic transitions of trivalent rare earth ions several luminescence bands were stated.

  2. History and Present Situation and Developing Tendency of Rare Earth Applied in Agriculture

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@History of rare earth applied in agriculture Concept of rare earth Rare earth(RE for short)is a general designation of 17 elements,including 15 elements of lanthanum system,they are lanthanum (La),cerium (Ce),praseodymium (Pr),neodymium (Nd),promethium(Pm),samarium(Sm),europium(Eu),gadolinium(Gd),terbium(Tb),dysprosium(Dy),holmium(Ho),erbium(Er),thulium(Tm),ytterbium(Yb),lutetium(Lu)),and 2 elements of the same clan with lanthanum system: scandium (Se)and yttrium (Y) in the periodic table of elements.Rare earth look like earth or soil,and their quantity which may be separated from ore are very rare or few,so scientists call them rare earth elements.

  3. Physical Properties of RE2 Ti3 Si4 (RE=Gd,Tb,Dy,Ho and Er)from First-principles Calculations%RE2 Ti3Si4(RE=Gd,Tb,Dy,Ho和Er)物理性质的第一性原理研究

    Institute of Scientific and Technical Information of China (English)

    陶小马; 陈晨; 郭子凤; 王戎丞; 陈红梅; 欧阳义芳

    2014-01-01

    【目的】对 RE2 Ti3 Si4(RE=Gd,Tb,Dy,Ho和 Er)的物理性能进行研究。【方法】利用基于密度泛函的第一性原理方法对 RE2 Ti3 Si4(RE=Gd,Tb,Dy,Ho 和 Er)的结构性质、电子结构、力学以及热力学性质进行计算。对RE2 Ti3 Si4单晶的弹性常数,多晶的体积模量、剪切模量和杨氏模量都进行了计算。利用准谐的德拜模型计算获得了体积模量、比热熔和热膨胀系数随着温度和压强的变化,并进行了相关的讨论。【结果】RE2 Ti3 Si4的晶格常数计算值和实验值吻合较好。【结论】形成焓的计算值随着稀土元素原子序数的增加而呈现微小的下降趋势,这表明化合物的稳定性随着原子序数的增加而加强。电子态密度显示在费米能级之下,Ti-3d和 RE-5d的态密度有着很强的杂化现象。%Objective]Physical properties of the RE2 Ti3 Si4 (RE=Gd,Tb,Dy,Ho and Er)are studied.[Methods]We present the structural,electronic structure,mechanical and thermody-namic properties of the RE2 Ti3 Si4 (RE=Gd,Tb,Dy,Ho and Er)by using first-principles calcu-lations based on the density functional theory (DFT).[Results]The calculated lattice constants of RE2 Ti3 Si4 are all in good agreement with experimental data.The single crystal elastic con-stants of RE2 Ti3 Si4 have been calculated,and the bulk,shear and Young's modulus are all been estimated in this work.Finally,using a quasi-harmonic Debye model,the bulk modulus,heat ca-pacity,and coefficient of thermal expansion have also been obtained and discussed.[Conclusion]The calculated formation enthalpies of the RE2 Ti3 Si4 show tiny decline trend with the increas-ing atomic number,which indicates that phase stability of RE2 Ti3 Si4 enhance slightly with in-creasing atomic number.The electronic densities of states indicate that Ti-3d and RE-5d peaks show strong hybridization below the Fermi level.

  4. 94 β -Decay Half-Lives of Neutron-Rich Cs 55 to Ho 67 : Experimental Feedback and Evaluation of the r -Process Rare-Earth Peak Formation

    Science.gov (United States)

    Wu, J.; Nishimura, S.; Lorusso, G.; Möller, P.; Ideguchi, E.; Regan, P.-H.; Simpson, G. S.; Söderström, P.-A.; Walker, P. M.; Watanabe, H.; Xu, Z. Y.; Baba, H.; Browne, F.; Daido, R.; Doornenbal, P.; Fang, Y. F.; Gey, G.; Isobe, T.; Lee, P. S.; Liu, J. J.; Li, Z.; Korkulu, Z.; Patel, Z.; Phong, V.; Rice, S.; Sakurai, H.; Sinclair, L.; Sumikama, T.; Tanaka, M.; Yagi, A.; Ye, Y. L.; Yokoyama, R.; Zhang, G. X.; Alharbi, T.; Aoi, N.; Bello Garrote, F. L.; Benzoni, G.; Bruce, A. M.; Carroll, R. J.; Chae, K. Y.; Dombradi, Z.; Estrade, A.; Gottardo, A.; Griffin, C. J.; Kanaoka, H.; Kojouharov, I.; Kondev, F. G.; Kubono, S.; Kurz, N.; Kuti, I.; Lalkovski, S.; Lane, G. J.; Lee, E. J.; Lokotko, T.; Lotay, G.; Moon, C.-B.; Nishibata, H.; Nishizuka, I.; Nita, C. R.; Odahara, A.; Podolyák, Zs.; Roberts, O. J.; Schaffner, H.; Shand, C.; Taprogge, J.; Terashima, S.; Vajta, Z.; Yoshida, S.

    2017-02-01

    The β -decay half-lives of 94 neutron-rich nuclei Cs-151144 , Ba-154146 , La-156148 , Ce-158150 , Pr-160153 , Nd-162156 , Pm-163159 , Sm-166160 , Eu-168161 , Gd-170165 , Tb-172166 , Dy-173169 , Ho-175172 , and two isomeric states Erm174 , Dym172 were measured at the Radioactive Isotope Beam Factory, providing a new experimental basis to test theoretical models. Strikingly large drops of β -decay half-lives are observed at neutron-number N =97 for Ce 58 , Pr 59 , Nd 60 , and Sm 62 , and N =105 for Eu 63 , Gd 64 , Tb 65 , and Dy 66 . Features in the data mirror the interplay between pairing effects and microscopic structure. r -process network calculations performed for a range of mass models and astrophysical conditions show that the 57 half-lives measured for the first time play an important role in shaping the abundance pattern of rare-earth elements in the solar system.

  5. Enhanced magnetostrictive effect in epoxy-bonded Tb{sub x}Dy{sub 0.9−x}Nd{sub 0.1}(Fe{sub 0.8}Co{sub 0.2}){sub 1.93} pseudo 1–3 particulate composites

    Energy Technology Data Exchange (ETDEWEB)

    Liu, J. J., E-mail: liujinjun1@nbu.edu.cn, E-mail: liujjimr@gmail.com; Pan, Z. B.; Song, X. H.; Zhang, Z. R. [Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211 (China); Ren, W. J. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2015-05-07

    The spin configuration and spontaneous magnetostriction λ{sub 111} of Tb{sub x}Dy{sub 0.9−x}Nd{sub 0.1}(Fe{sub 0.8}Co{sub 0.2}){sub 1.93} (0.20 ≤ x ≤ 0.60) alloys have been investigated. The easy magnetization direction (EMD) at room temperature was observed towards the 〈111〉 axis when 0.40 ≤ x ≤ 0.60, accompanied by a rhombohedral distortion with large spontaneous magnetostriction coefficients λ{sub 111}, which increases from 1640 ppm for x = 0.40 to 1900 ppm for x = 0.60. The strong 〈111〉-oriented pseudo 1–3 particulate composite was fabricated by embedding and aligning particles in a passive epoxy matrix under an applied magnetic field. An enhanced magnetostrictive effect, the large low-field magnetostriction, λ{sub a}, as high as 480 ppm at 3 kOe, was obtained for the sample of x = 0.40, in an excess of 75% of its polycrystalline alloy although it only contains 27 vol. % alloy particles. This enhanced effect can be attributed to its low magnetic anisotropy, anisotropic magnetostrictive nature (e.g., λ{sub 111} ≠ λ{sub 100,} 〈111〉EMD), chain structure, and the 〈111〉-textured orientation. In addition, we give a direct experimental support that the 〈111〉EMD of particle and the strong 〈111〉-textured orientation are the crucial factors to realize the enhanced magnetostrictive effect in 1–3 particulate composites.

  6. Co(II)4, Co(II)7, and a Series of Co(II)2Ln(III) (Ln(III) = Nd(III), Sm(III), Gd(III), Tb(III), Dy(III)) Coordination Clusters: Search for Single Molecule Magnets.

    Science.gov (United States)

    Modak, Ritwik; Sikdar, Yeasin; Thuijs, Annaliese E; Christou, George; Goswami, Sanchita

    2016-10-03

    We report herein the syntheses and investigation of the magnetic properties of a Co(II)4 compound, a series of trinuclear Co(II)2Ln(III) (Ln(III) = Nd(III), Sm(III), Gd(III), Tb(III), Dy(III)) complexes, and a Co(II)7 complex. The homometallic Co(II)4 core was obtained from the reaction of Ln(NO3)3·xH2O/Co(NO3)2·6H2O/H2vab/Et3N in a 0.5:0.5:1:2 ratio in methanol. Variation in synthetic conditions was necessary to get the desired Co(II)-Ln(III) complexes. The Co(II)-Ln(III) assembly was synthesized from Ln(NO3)3·xH2O/Co(OAc)2·4H2O/H2vab/NaOMe in a 0.4:0.5:1:1 ratio in methanol. The isostructural Co(II)2Ln(III) complexes have a core structure with the general formula [Co2Ln(Hvab)4(NO3)](NO3)2·MeOH·H2O, (where H2vab = 2-[(2-hydroxymethyl-phenylimino)-methyl]-6-methoxy-phenol) with simultaneous crystallization of Co(II)7 complex in each reaction. The magnetic investigation of these complexes reveals that both homometallic complexes and four Co(II)-Ln(III) complexes (except Co(II)-Nd(III)) display behavior characteristic of single molecule magnets.

  7. Study on optical properties of rare-earth ions in nanocrystalline monoclinic SrAl2O4: Ln (Ln = Ce3+, Pr3+, Tb3+).

    Science.gov (United States)

    Fu, Zuoling; Zhou, Shihong; Zhang, Siyuan

    2005-08-01

    SrAl(2)O(4): Ln (Ln = Ce(3+), Pr(3+), Tb(3+)) nanocrystals have been synthesized by the combustion method. The results of XRD indicated that the resulting SrAl(2)O(4): Ln (Ln = Ce(3+), Pr(3+), Tb(3+)) nanocrystals have a reduced and distorted monoclinic lattice compared with bulk materials. The spectral properties are measured, and it is found that the excitation peaks of 5d energy levels red shift in nanocrystals in contrast to that in bulk crystals. The mechanism of spectra and energy changes is investigated. The order of the degree of red shift for nano SrAl(2)O(4): Ln (Ln = Ce(3+), Pr(3+), Tb(3+)) crystals is Pr(3+) > Ce(3+) > Tb(3+), which is in good agreement with our predicted results.

  8. Chemical environment of rare earth ions in Ge{sub 28.125}Ga{sub 6.25}S{sub 65.625} glass-ceramics doped with Dy{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Rongping, E-mail: rongping.wang@anu.edu.au; Yan, Kunlun; Luther-Davies, Barry [Centre for Ultrahigh bandwidth Devices for Optical Systems, Laser Physics Centre, Research School of Physics and Engineering, The Australian National University, Canberra ACT 2600 (Australia); Zhang, Mingjie; Yang, Anping; Zhang, Bin [Jiangsu Key Laboratory of Advanced Laser Materials and Devices, School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou, Jiangsu 221116 (China); Shen, Xiang; Dai, Shixun [Laboratory of Infrared Material and Devices, The Advanced Technology Research Institute, Ningbo University, Ningbo 315211 (China); Yang, Xinyu [Faculty of Chemistry and Material Engineering, Wenzhou University, Wenzhou 325027 (China); Yang, Zhiyong [Centre for Ultrahigh bandwidth Devices for Optical Systems, Laser Physics Centre, Research School of Physics and Engineering, The Australian National University, Canberra ACT 2600 (Australia); Jiangsu Key Laboratory of Advanced Laser Materials and Devices, School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou, Jiangsu 221116 (China)

    2015-10-19

    We have annealed Ge{sub 28.125}Ga{sub 6.25}S{sub 65.625} glasses doped with 0.5% Dy to create glass-ceramics in order to examine the local chemical environment of the rare earth ions (REI). More than 12 times enhancement of the emission at 2.9 and 3.5 μm was achieved in glass-ceramics produced using prolonged annealing time. Elemental mapping showed clear evidence that Ga{sub 2}S{sub 3} crystalline grains with a size of 50 nm were dispersed in a Ge-S glass matrix in the glass-ceramics, and the REI could only be found near the Ga{sub 2}S{sub 3} crystalline grains. From the unchanged lineshape of the emissions at 2.9 and 3.5 μm and lack of splitting of the absorption peaks, we concluded that the REI were bonded to Ga on the surface of the Ga{sub 2}S{sub 3} crystals.

  9. Trends in Syntheses, Structures, and Properties for Three Series of Ammine Rare-Earth Metal Borohydrides, M(BH4)3·nNH3 (M = Y, Gd, and Dy).

    Science.gov (United States)

    Jepsen, Lars H; Ley, Morten B; Černý, Radovan; Lee, Young-Su; Cho, Young Whan; Ravnsbæk, Dorthe; Besenbacher, Flemming; Skibsted, Jørgen; Jensen, Torben R

    2015-08-03

    Fourteen solvent- and halide-free ammine rare-earth metal borohydrides M(BH4)3·nNH3, M = Y, Gd, Dy, n = 7, 6, 5, 4, 2, and 1, have been synthesized by a new approach, and their structures as well as chemical and physical properties are characterized. Extensive series of coordination complexes with systematic variation in the number of ligands are presented, as prepared by combined mechanochemistry, solvent-based methods, solid-gas reactions, and thermal treatment. This new synthesis approach may have a significant impact within inorganic coordination chemistry. Halide-free metal borohydrides have been synthesized by solvent-based metathesis reactions of LiBH4 and MCl3 (3:1), followed by reactions of M(BH4)3 with an excess of NH3 gas, yielding M(BH4)3·7NH3 (M = Y, Gd, and Dy). Crystal structure models for M(BH4)3·nNH3 are derived from a combination of powder X-ray diffraction (PXD), (11)B magic-angle spinning NMR, and density functional theory (DFT) calculations. The structures vary from two-dimensional layers (n = 1), one-dimensional chains (n = 2), molecular compounds (n = 4 and 5), to contain complex ions (n = 6 and 7). NH3 coordinates to the metal in all compounds, while BH4(-) has a flexible coordination, i.e., either as a terminal or bridging ligand or as a counterion. M(BH4)3·7NH3 releases ammonia stepwise by thermal treatment producing M(BH4)3·nNH3 (6, 5, and 4), whereas hydrogen is released for n ≤ 4. Detailed analysis of the dihydrogen bonds reveals new insight about the hydrogen elimination mechanism, which contradicts current hypotheses. Overall, the present work provides new general knowledge toward rational materials design and preparation along with limitations of PXD and DFT for analysis of structures with a significant degree of dynamics in the structures.

  10. Synthesis, Characterization and Fluorescence of Rare earth Nitrate Complexes with Triaza-crown Ether Derivative

    Institute of Scientific and Technical Information of China (English)

    胡晓黎; 崔书亚; 闫兰; 杨汝栋

    2003-01-01

    Four new complexes of rare earths with a triaza-crown ether (L) derived from N3O2-macro cycle 1,12,15-triaza-3, 4: 9,10-dibenzo-5, 8-dioxacycloheptadecane were synthesized and characterized by elemental analysis, IR, molar conductance, TG-DTA analysis and fluorescence spectra. The composition of the complexes determined as [RE(NO3)3L*3H2O]*H2O (RE=Sm, Eu, Tb and Dy). It is found that Sm3+, Eu3+, Tb3+ and Dy3+ complexes all show strong fluorescence emission in the solid state. Among these complexes, Tb3+ complex has the strongest luminescence intensity. It shows that the ligand L triplet state energy matches 5D4 energy level of Tb3+. In the Eu3+ complex, η(5D0→7F2/5D0→7F1) is 2.6, which indicates that Eu3+ locates at the asymmetric coordination field.

  11. Synthesis and structural characterization of the new rare-earth borosilicates Pr{sub 3}BSi{sub 2}O{sub 10} and Tb{sub 3}BSi{sub 2}O{sub 10}

    Energy Technology Data Exchange (ETDEWEB)

    Braeuchle, Sebastian; Huppertz, Hubert [Innsbruck Univ. (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie

    2015-07-01

    The rare-earth borosilicates RE{sub 3}BSi{sub 2}O{sub 10} (RE = Pr, Tb) were synthesized under high-temperature conditions of 1600 C in a radio frequency furnace from praseodymium oxide, terbium oxide, silicon dioxide, silicon nitride, boron trioxide, and boric acid. The structure determinations based on powder diffraction data revealed that both phases RE{sub 3}BSi{sub 2}O{sub 10} (RE = Pr, Tb) are isotypic to Gd{sub 3}BSi{sub 2}O{sub 10} [L. Chi, H. Chen, X. Lin, H. Zhuang, J. Huang, Jiegou Huaxue 1998, 17, 297]. The compounds crystallize in the orthorhombic space group Pbca (no. 61) with eight formula units and the lattice parameters a = 982.9(2), b = 714.2(2), c = 2314.4(4) pm, V = 1.6247(4) nm{sup 3}, R{sub p} = 0.0231, and R{sub wp} = 0.0354 (all data) for Pr{sub 3}BSi{sub 2}O{sub 10} and a = 960.5(5), b = 692.1(3), c = 2272.4(1) pm, V = 1.5106(2) nm{sup 3} for Tb{sub 3}BSi{sub 2}O{sub 10}. The lattice parameters of Tb{sub 3}BSi{sub 2}O{sub 10} could be determined, but a final refinement of the powder data has not proved satisfactory. The structure of Pr{sub 3}BSi{sub 2}O{sub 10} exhibits eight- (Pr1) and ninefold coordinated rare-earth cations (Pr2 and 3). Layers of ortho-silicate anions [SiO{sub 4}]{sup 4-} and borosilicate anions [BSiO{sub 6}]{sup 5-} are arranged alternatingly along the c axis and the RE cations are located in between.

  12. Quadrupole moment of superdeformed bands in Tb-151

    NARCIS (Netherlands)

    Finck, C; Stezowski, O; Beck, FA; Appelbe, DE; Byrski, T; Courtin, S; Cullen, DM; Curien, D; de France, G; Duchene, G; Erturk, S; Gall, BJP; Garg, U; Haas, B; Khadiri, N; Kharraja, B; Kintz, N; Nourreddine, A; Prevost, D; Rigollet, C; Savajols, H; Twin, PJ; Vivien, JP; Zuber, K

    1998-01-01

    The quadrupole moments of the first two superdeformed (SD) bands in the nucleus Tb-151 have been measured with the Doppler Shift Attenuation Method (DSAM) using the EUROGAM gamma-ray spectrometer, The first excited band (B2) is identical to the yrast SD band of Dy-152 in terms of dynamical moments o

  13. The K-Forbidden Beta Decay of Tb160

    DEFF Research Database (Denmark)

    Hansen, P. Gregers; Johnson, N. R.; Nielsen, H. L.

    1964-01-01

    The β decay of the odd nucleus Tb160(Iπ = 3−) is shown to populate the 2+ and 4+ states of the ground-state band of Dy160 in intensities of 0.34% and 0.12%, respectively. The ratio of the reduced transition probabilities and the absolute transition strength are both compared with theoretical...

  14. Quadrupole moment of superdeformed bands in Tb-151

    NARCIS (Netherlands)

    Finck, C; Stezowski, O; Beck, FA; Appelbe, DE; Byrski, T; Courtin, S; Cullen, DM; Curien, D; de France, G; Duchene, G; Erturk, S; Gall, BJP; Garg, U; Haas, B; Khadiri, N; Kharraja, B; Kintz, N; Nourreddine, A; Prevost, D; Rigollet, C; Savajols, H; Twin, PJ; Vivien, JP; Zuber, K

    The quadrupole moments of the first two superdeformed (SD) bands in the nucleus Tb-151 have been measured with the Doppler Shift Attenuation Method (DSAM) using the EUROGAM gamma-ray spectrometer, The first excited band (B2) is identical to the yrast SD band of Dy-152 in terms of dynamical moments

  15. TB & Tobacco

    Directory of Open Access Journals (Sweden)

    Tjandra Y. Aditama

    2003-03-01

    Full Text Available One third of the world population is infected with tuberculosis, and over 8 millions people were developing each year. On the other hand tobacco is responsible for 3 millions death in the world. For Indonesia, our country has the third biggest TB cases in the world. Whereas Indonesia is ranked as having the fourth largest number of smokers in the world. A relationship between smoking and TB has been suspected for a long time, even though the epidemiological evidence has not been convincing so far, as well as the pathophysiology and the biomolecullar changes. At present time there are more and more epidemiological data to suggest relationship between TB and tobacco. Further research should be done to get more indepth relationship as well as avoiding the confounder factor. To be able to perform TB control as well as tobacco control successfully there should be emphasize on synergistic public health approaches. Tuberculosis –which Indonesia got 3rd rank in the world- as well as smoking problem –which Indonesia got 4th rank in the world- are two important public health problem for the country. If there are relationship between tobacco and tuberculosis, health problem faced by Indonesian even become bigger. Knowledge about tuberculosis as well as tobacco among Indonesian population is very essential to improve the public health situation. Tuberculosis control programme as well as smoking control programme are essential tools for the well being of Indonesian people. (Med J Indones 2003; 12: 48-52 Keywords: tobacco, tuberculosis, epidemiological data

  16. Difference Between Latent TB Infection and Active TB Disease

    Science.gov (United States)

    ... infected by a person with multidrug-resistant TB (MDR TB) or extensively drug-resistant TB (XDR TB), preventive ... faqs/ default. htm 3. CDC. Multidrug-Resistant Tuberculosis (MDR TB) . http: / / www. cdc. gov/ tb/ publications/ factsheets/ drtb/ ...

  17. Strain-induced modification of magnetic structure and new magnetic phases in rare-earth epitaxial films

    Indian Academy of Sciences (India)

    C Dufour; K Dumesnil; Ph Mangin

    2006-07-01

    Rare earths exhibit complex magnetic phase diagrams resulting from the competition between various contributions to the magnetic energy: exchange, anisotropy and magnetostriction. The epitaxy of a rare-earth film on a substrate induces (i) a clamping to the substrate and (ii) pseudomorphic strains. Both these effects are shown to lead to modifications of the magnetic properties in (0 0 1)Dy, (0 0 1)Tb and (1 1 0)Eu films. In Dy and Tb films, spectacular variations of the Curie temperature have been evidenced. Additionally, Tb films exhibit a new large wavelength magnetic modulation. In Eu films, one of the helical magnetic domains disappears at low temperature whereas the propagation vectors of the other helices are tilted. The link between structural and magnetic properties is underlined via magnetoelastic models. Moreover, molecular beam epitaxy permits the growth of Sm in a metastable dhcp phase. The magnetic structure of dhcp Sm has been elucidated for the first time. In this review, neutron scattering is shown to be a powerful technique to reveal the magnetic structures of rare-earth films.

  18. Magnetic properties of rare-earth-doped La0.7Sr0.3MnO3

    Science.gov (United States)

    Veverka, Pavel; Kaman, Ondřej; Knížek, Karel; Novák, Pavel; Maryško, Miroslav; Jirák, Zdeněk

    2017-01-01

    Rare-earth-doped ferromagnetic manganites La0.63RE0.07Sr0.30MnO3 (RE  =  Gd, Tb, Dy, and Ho) are synthesized in the form of sintered ceramics and nanocrystalline phases with the mean size of crystallites  ≈30 nm. The electronic states of the dopants are investigated by SQUID magnetometry and theoretically interpreted based on the calculations of the crystal field splitting of rare-earth energy levels. The samples show the orthorhombic perovskite structure of Ibmm symmetry, with a complete FM order of Mn spins in bulk and reduced order in nanoparticles. Non-zero moments are also detected at the perovskite A sites, which can be attributed to magnetic polarization of the rare-earth dopants. The measurements in external field up to 70 kOe show a standard Curie-type contribution of the spin-only moments of Gd3+ ions, whereas Kramers ions Dy3+ and non-Kramers ions Ho3+ contribute by Ising moments due to their doublet ground states. The behaviour of non-Kramers ions Tb3+ is anomalous, pointing to singlet ground state with giant Van Vleck paramagnetism. The Tb3+ doping leads also to a notably increased coercivity compared to other La0.63RE0.07Sr0.30MnO3 systems.

  19. LiDy(PO34

    Directory of Open Access Journals (Sweden)

    Fathia Chehimi-Moumen

    2008-07-01

    Full Text Available Single crystals of lithium dysprosium polyphosphate, LiDy(PO34, were prepared by the flux method. The atomic arrangement is built up by infinite (PO3n 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.

  20. Magnetic properties and XPS of Dy-Y and Dy-Nd alloys

    Institute of Scientific and Technical Information of China (English)

    戴闻; 沈保根; 李德新; 何文望; 叶小燕

    1996-01-01

    The magnetic properties and X-ray photoelectron spectroscopy (XPS) spectra in the Dy100-xYx and Dy100-zNdz rare-earth alloys are studied.The magnetism measurements show that the dhcp crystal-field influence in the Dy-Nd alloys,which tends to destroy the orbital moment,does not vanish even though a field of 6T is applied.With increasing Y (or Nd) content the temperature region corresponding to helical phase becomes wider (or narrower).The XPS records suggest that the property of the valence fluctuation in neodymium tends to increase the Fermi wave vector kF of the Dy-Nd alloys.This testifies that the abrupt dropping of the Neel temperature,as Nd is introduced,is not only due to a dilution effect of Nd.The introduction of light rare earths into heavy ones is favorable for suppressing the helical phase in the alloys and overcoming the negative magnetocaloric effect.This result will play a guiding role in designing composite magnetic refrigeration working substances.

  1. Magnetic structures and related properties of some rare-earth intermetallic compounds, RCu 2

    Science.gov (United States)

    Lebech, B.; Smetana, Z.; S̆íma, V.

    1987-12-01

    The magnetic structures and some relevant bulk magnetic properties of R(Cu, Ni) 2 (R = Tb, Tb zY 1- z, Dy, Ho, Er and Tm) are summarized. Basically, the magnetic structures are antiferromagnetically modulated with propagation vector {1}/{3}a∗. For R = Tb, Dy, Ho the a-axis anisotropy dominates and the structures are longitudinally modulated. For R = Tm, Er (probably) the b-axis anisotropy dominates and this results in transversely modulated structures. For R = Tb, Dy the structures are collinear, For R = Ho, Er, Tm (probably) an incommensurate modulation coexists with the commensurate a∗-axis modulation at the lowest temperature.

  2. Systematic study of the fragmentation of low-lying dipole strength in odd-{ital A} rare earth nuclei investigated in nuclear resonance fluorescence experiments

    Energy Technology Data Exchange (ETDEWEB)

    Nord, A.; Schiller, A.; Eckert, T.; Beck, O.; Besserer, J.; von Brentano, P.; Fischer, R.; Herzberg, R.; Jaeger, D.; Kneissl, U.; Margraf, J.; Maser, H.; Pietralla, N.; Pitz, H.H.; Rittner, M.; Zilges, A. [Institut fuer Strahlenphysik, Universitaet Stuttgart, Allmandring 3, D-70569 Stuttgart (Germany)]|[Institut fuer Kernphysik, Universitaet zu Koeln, Zuelpicher Strasse 77, D-50937 Koeln (Germany)

    1996-11-01

    Nuclear resonance fluorescence experiments were performed on the rare earth nuclei {sup 155}Gd and {sup 159}Tb to study the fragmentation of the {ital M}1 {ital scissors} {ital mode} in {ital odd} deformed nuclei and to establish a kind of systematics. Using the bremsstrahlung photon beam of the Stuttgart Dynamitron (end point energy 4.1 MeV) and high resolution Ge-{gamma} spectrometers detailed information was obtained on excitation energies, decay widths, transition probabilities, and branching ratios. The results are compared to those observed recently for the neighboring odd nuclei {sup 161,163}Dy and {sup 157}Gd. Whereas in the odd Dy isotopes the dipole strength is rather concentrated, both Gd isotopes show a strong fragmentation of the strength into about 25 ({sup 155}Gd) and 90 transitions ({sup 157}Gd) in the energy range 2{endash}4 MeV. The nucleus {sup 159}Tb linking the odd Dy and Gd isotopes exhibits an intermediate strength fragmentation. In general the observed total strength in the odd nuclei is reduced by a factor of 2{endash}3 as compared to their neighboring even-even isotopes. The different fragmentation behavior of the dipole strengths in the odd Dy and Gd isotopes is unexplained up to now. {copyright} {ital 1996 The American Physical Society.}

  3. Systematic study of the fragmentation of low-lying dipole strength in odd-A rare earth nuclei investigated in nuclear resonance fluorescence experiments

    Science.gov (United States)

    Nord, A.; Schiller, A.; Eckert, T.; Beck, O.; Besserer, J.; von Brentano, P.; Fischer, R.; Herzberg, R.-D.; Jäger, D.; Kneissl, U.; Margraf, J.; Maser, H.; Pietralla, N.; Pitz, H. H.; Rittner, M.; Zilges, A.

    1996-11-01

    Nuclear resonance fluorescence experiments were performed on the rare earth nuclei 155Gd and 159Tb to study the fragmentation of the M1 scissors mode in odd deformed nuclei and to establish a kind of systematics. Using the bremsstrahlung photon beam of the Stuttgart Dynamitron (end point energy 4.1 MeV) and high resolution Ge-γ spectrometers detailed information was obtained on excitation energies, decay widths, transition probabilities, and branching ratios. The results are compared to those observed recently for the neighboring odd nuclei 161,163Dy and 157Gd. Whereas in the odd Dy isotopes the dipole strength is rather concentrated, both Gd isotopes show a strong fragmentation of the strength into about 25 (155Gd) and 90 transitions (157Gd) in the energy range 2-4 MeV. The nucleus 159Tb linking the odd Dy and Gd isotopes exhibits an intermediate strength fragmentation. In general the observed total strength in the odd nuclei is reduced by a factor of 2-3 as compared to their neighboring even-even isotopes. The different fragmentation behavior of the dipole strengths in the odd Dy and Gd isotopes is unexplained up to now.

  4. The Rare Earth Magnet Industry and Rare Earth Price in China

    Directory of Open Access Journals (Sweden)

    Ding Kaihong

    2014-07-01

    Full Text Available In the past four years, the price of rare earth metal fluctuates sharply for many reasons. Currently, it has become more stable and more reasonable. This presentation is focused on the effect about the rare earth metal price. Some motor manufacturers have shifted from rare earth permanent magnet to ferrite magnet. Many motor manufacturers changed the design for the motor cooling system to make the motor function at a lower temperature. Thus the consumption of Dy can be markedly reduced. As for manufacturer of NdFeB magnet, we are also trying to optimize our process to reduce to dependence of HREE such as Dy and Tb. HS process have been introduced to solve the problem. With more and more people focusing and engaging on the REE industry, the price of REE will be more transparent without too many fluctuations. China is considering the problems of balancing the environment, energy sources, and labor sources. The application field about NdFeB such as wind turbine generator, HEV/EV, FA /OA is flourishing.

  5. Synthesis and Characterization of a Novel Compound SnDy2O4

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A new phase, the rare earth complex oxide SnDy2O4 was synthesized by the thermal decomposition of its oxalate precursor that was prepared by rheological phase reaction method. TG, IR, XRD and EPS were used to prove the formation of the compound SnDy2O4. The structure of SnDy2O4 was refined by Rietveld analysis. SnDy2O4 is cubic, a = 7.40366A, V = 405.82A3, Z = 4.

  6. Testing for TB Infection

    Science.gov (United States)

    ... the Facts Tuberculosis - The Connection between TB and HIV 12-Dose Regimen for Latent TB Infection-Patient Education Brochure Posters Mantoux Tuberculin Skin Test Wall Chart World TB Day Think TB Stop TB Reports & Articles Morbidity and Mortality Weekly Reports (MMWRs) DTBE Authored ...

  7. Evidence of Coulomb correction and spin-orbit coupling in rare-earth dioxides CeO{sub 2}, PrO{sub 2} and TbO{sub 2}: An ab initio study

    Energy Technology Data Exchange (ETDEWEB)

    Kanoun, Mohammed Benali, E-mail: mohammmed.kanoun@kaust.edu.sa [PSE, KAUST, Thuwal 23955-6900 (Saudi Arabia); Reshak, Ali H. [School of Complex Systems, FFWP-South Bohemia University, Nove Hrady 37333 (Czech Republic); School of Material Engineering, Malaysia University of Perlis, P.O Box 77, d/a Pejabat Pos Besar, 01007 Kangar, Perlis (Malaysia); Kanoun-Bouayed, Nawel [PES, LPT, Universite de Tlemcen (Algeria); Goumri-Said, Souraya [PSE, KAUST, Thuwal 23955-6900 (Saudi Arabia)

    2012-04-15

    The current study investigates the structural, elastic, electronic and optical properties of CeO{sub 2}, PrO{sub 2} and TbO{sub 2} using the full potential (linearized) augmented plane wave plus local orbital method within the Wu-Cohen generalized gradient approximation (GGA) with Hubbard (U) correction and spin-orbit coupling (SOC). The GGA+U implementation lead us to describe correctly the relativistic effect on 4f electrons for CeO{sub 2}. We clarify that the inclusion of the Hubbard U parameter and the spin-orbit coupling are responsible for the ferromagnetic insulating of PrO{sub 2} and TbO{sub 2}. The magnetic description is achieved by the spin-density contours and magnetic moment calculations, where we show the polarization of oxygen atoms from the rare earth atoms. The mechanical stability is shown via the elastic constants calculations. The optical properties, namely the dielectric function and the reflectivity are calculated for radiation up to 12 eV, giving interesting optoelectronic properties to these dioxides. - Highlights: Black-Right-Pointing-Pointer GGA+U implementation lead us to describe correctly the relativistic effect on 4f electrons for CeO{sub 2}. Black-Right-Pointing-Pointer Inclusion of the Hubbard-U parameter and spin-orbit coupling is responsible for ferromagnetic insulating of PrO{sub 2} and TbO{sub 2}. Black-Right-Pointing-Pointer Elastic constants calculation proves the mechanical stability of CeO{sub 2}, PrO{sub 2} and TbO{sub 2}. Black-Right-Pointing-Pointer The electronic structure description shows that these compounds are stable in ferromagnetic phases.

  8. Phase relationship of Dy-Fe-Mn system at 773 K

    Institute of Scientific and Technical Information of China (English)

    杜成梅; 马君; 姚路; 陈国坚; 杨通晗; 曾维敬; 何维

    2014-01-01

    Rare-earth intermetallic compounds formed in many R-Fe-Mn (R=rare-earth element) systems exhibit excellent properties. In order to understand the existence and stability of the compounds in the system and further search for the potential application of R-Fe-Mn alloys in various aspects, it is necessary to investigate the phase relations of the Dy-Fe-Mn ternary system. A total of 96 samples of the Dy-Fe-Mn alloys were prepared by arc-melting and examined by metallographic analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques. The phase relationship of the Dy-Fe-Mn system at 773 K was determined. It was found that the isothermal section was characterized by intermediate solid solutions based on the substitutions of Fe/Mn atoms and the large extensions of the binaries into the ternary domains. The solid solubilities of the third ele-ment in the binary compounds and the phase boundaries were also determined by XRD technique using the phase disappearing method combined with the lattice parameter method and SEM/EDS technique. Two pairs of corresponding binary compounds in the Dy-Fe and Dy-Mn systems (DyFe2 and DyMn2, Dy6Fe23 and Dy6Mn23) formed a continuous series of solid solution at 773 K, respectively.

  9. Simultaneous Determination of Trace Rare Earth Elements and Other Elements in High Purity Terbium Oxide (Tb4O7) by ICP-AES After HPLC Separation Using P507 Resin

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This article describes a new method for the simultaneous determination of trace rare earth elements (REEs) and non rare earth elements (NREEs) in high purity terbium oxide by ICP-AES after HPLC separation using P507 resin. The chromatographic separation of the analytes from the matrix using dilute nitric acid as mobile phase was studied. The experimental results showed that a favorable separation of trace metals (Cu and Gd) from the matrix (Tb) can easily be achieved by elution with dilute nitric acid within 25 min. The proposed method was applied to the determination of trace metals (Ca, Cu, Mg, Mn, Ni, Si, La, Ce, Pr, Nd, Sm, Eu and Gd) in high purity terbium oxide. The detection limits (DLs) for the analytes ranged from 0.4-4.0 μg\\5g-1, and the recoveries are from 78%-105%.

  10. Effect of rare earth ion in the thermopower of R{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} compounds with x{approx}0.5 and R=Gd and Tb

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, A.M. [IFIMUP, Rua do Campo Alegre, 678, 4169-007 Porto (Portugal)]. E-mail: ampereira@fc.up.pt; Magen, C. [Instituto de Ciencia de Materiales de Aragon Universidad de Zaragoza and Consejo Superior de Investigaciones Cient icas, 50009 Zaragoza (Spain); Araujo, J.P. [IFIMUP, Rua do Campo Alegre, 678, 4169-007 Porto (Portugal); Algarabel, P.A. [Instituto de Ciencia de Materiales de Aragon Universidad de Zaragoza and Consejo Superior de Investigaciones Cient icas, 50009 Zaragoza (Spain); Morellon, L. [Instituto de Ciencia de Materiales de Aragon Universidad de Zaragoza and Consejo Superior de Investigaciones Cient icas, 50009 Zaragoza (Spain); Instituto de Nanociencia de Aragon, 50009 Zaragoza (Spain); Braga, M.E. [IFIMUP, Rua do Campo Alegre, 678, 4169-007 Porto (Portugal); Pinto, R.P. [IFIMUP, Rua do Campo Alegre, 678, 4169-007 Porto (Portugal); Ibarra, M.R. [Instituto de Ciencia de Materiales de Aragon Universidad de Zaragoza and Consejo Superior de Investigaciones Cient icas, 50009 Zaragoza (Spain); Instituto de Nanociencia de Aragon, 50009 Zaragoza (Spain); Sousa, J.B. [IFIMUP, Rua do Campo Alegre, 678, 4169-007 Porto (Portugal)

    2007-03-15

    The magnetocaloric ferromagnetic compounds with R{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} composition are very sensitive to the Si:Ge ratio (x) and the particular Rare earth (R) ion. Here we study the thermopower S(T) behavior of samples with a similar x{approx}0.5 ratio but different rare earth ions: Gd{sub 5}(Si{sub 0.45}Ge{sub 0.55}){sub 4} and Tb{sub 5}(Si{sub 0.5}Ge{sub 0.5}){sub 4}, between 10 and 290K. Above the Curie temperature (T{sub C}) both S and its T-dependence do not change with the R-ion but, upon cooling, a first-order magneto-structural transition occurs at T{sub S} (close to T{sub C}) causing an abruptness in thermopower ({delta}S/S{approx}32%). At low temperatures very distinct S(T) behavior is observed, and a spin reorientation transition occurs in the Tb compound.

  11. Tuberculosis (TB): Treatment

    Science.gov (United States)

    ... Training Home Conditions Tuberculosis (TB) Treating Tuberculosis Treating Tuberculosis Make an Appointment Refer a Patient Ask a ... bones is treated longer. NEXT: Preventive Treatment Diagnosing Tuberculosis History of TB Clinical Trials Tuberculosis (TB) Causes ...

  12. 稀土金属 Dy 掺杂 TiO2光催化剂的制备及其对孔雀石绿降解性能的研究%Study on preparation of rare earth element dysprosium doped with TiO2 photocatalyst and its degradation property to malachite green

    Institute of Scientific and Technical Information of China (English)

    高航; 高梅; 李松田; 马威; 吴晓兵

    2015-01-01

    To improve the oxidation efficiency of heterogeneous photocatalysis,TiO2 doped by rare-earth elements was adopted. The results indicate that:there was red-shift adsorption spectra of synthetic product which could enhance malachite green oxidative decolorization effectively under the action of normal visible light. Due to Dy3 + -TiO2 doped photocatalyst,activation energy of photooxidation was decreased so that the efficiency of photolysis could be improved significantly. What’s more,the treatment of malachite green model wastewater with Dy3 + -TiO2 was studied and optimal conditions has been determined as follows:the concentration of malachite green is 20 mg / L,molar ratio of Dy-doping is 1. 5% . Under that reaction con-dition,after 150 min,the decolorization rates of malachite green will be over 60% .%采用稀土元素掺杂法制备改性的二氧化钛,以改善非均相光催化的氧化效率。研究结果表明,在掺杂镝元素之后,产物的吸收光谱发生了红移,在可见光作用下,可以有效地促进孔雀石绿的氧化脱色。引入掺杂型光催化剂 Dy3+-TiO2后,可降低光氧化体系所需的能量,提高光解效率。以孔雀石绿溶液作为模拟废水,考察了 Dy3+离子掺杂量、底物浓度等因素的影响,确定了优化的实验条件:在孔雀石绿的浓度为20 mg/ L,稀土元素 Dy 掺杂量为1.5%(摩尔比)时,反应150 min 后孔雀石绿脱色率达到60%以上。

  13. Measurement of formation cross sections of short-lived nuclei by 14 MeV neutron. Nd, Sm, Dy, Er, Yb

    Energy Technology Data Exchange (ETDEWEB)

    Sakane, H.; Yamamoto, H.; Kawade, K. [Nagoya Univ. (Japan). School of Engineering; Iida, T.; Takahashi, A.

    1997-03-01

    Eight neutron activation cross sections producing the nuclei with half-lives between 3 min and 24 min were obtained at the energy range between 13.4 and 14.9 MeV by activation method. The cross sections were {sup 146}Nd(n,p){sup 146}Pr, {sup 154}Sm(n,{alpha}){sup 151}Nd, {sup 162}Dy(n,p){sup 162}Tb, {sup 163}Dy(n,np){sup 162}Tb, {sup 163}Dy(n,p){sup 163}Tb, {sup 164}Dy(n,p){sup 164}Tb, {sup 170}Er(n,{alpha}){sup 167}Dy, {sup 174}Yb(n,p){sup 170}Tm. {sup 163}Dy(n,np){sup 162}Tb (T{sub 1/2}=7.7 min) was obtained for the first time. Present results are compared with previous results and the evaluated data of JENDL-3 and ENDF/B-VI. There are some discrepancies between present results and the JENDL-3 and ENDF/B-VI. (author)

  14. Effect of Dy addition on mechanical and magnetic properties of Mn-rich Ni-Mn-Ga ferromagnetic shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gao, L., E-mail: lgao@shou.edu.cn [College of Engineering Science and Technology, Shanghai Ocean University, Shanghai 201306 (China); Dong, G.F. [Department of Physics, Dalian University, Dalian 116622 (China); Gao, Z.Y.; Cai, W. [School of Materials Science and Engineering, P.O. Box 405, Harbin Institute of Technology, Harbin, 150001 (China)

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer The Dy addition significantly improves the compressive properties of Ni-Mn-Ga alloy. Black-Right-Pointing-Pointer The mechanism of the improved mechanical properties by adding Dy is discussed. Black-Right-Pointing-Pointer Dy doping results in a change of the fracture type of Ni-Mn-Ga alloy. Black-Right-Pointing-Pointer Curie temperature almost remained unchanged at low Dy content and then decreases. - Abstract: The effects of partial substitution of rare earth Dy for Ga on the mechanical and magnetic properties of Mn-rich Ni{sub 50}Mn{sub 29}Ga{sub 21-x}Dy{sub x} (0 {<=} x {<=} 5) ferromagnetic shape memory alloys were investigated in detail. The results show that an appropriate amount of Dy addition significantly improves the mechanical properties of Ni-Mn-Ga alloy. With an increase in Dy content, the compressive strength enhances rapidly at first and then becomes stable when the Dy content is more than 1 at.%. However, the compressive strain increases dramatically and reaches a maximum value with 1 at.% Dy addition. Further increase in Dy content makes the compressive strain of the alloys decrease gradually. The mechanism of the improved mechanical properties is also discussed. Moreover, Dy doping changes the fracture type from intergranular fracture of Ni-Mn-Ga alloy to transgranular cleavage fracture of Ni-Mn-Ga-Dy alloys. The Curie temperature remains almost unchanged at low Dy content and subsequently decreases.

  15. Gyroscopic g factor of rare earth metals

    Science.gov (United States)

    Ogata, Y.; Chudo, H.; Ono, M.; Harii, K.; Matsuo, M.; Maekawa, S.; Saitoh, E.

    2017-02-01

    We develop the in situ magnetization measurement apparatus for observing the Barnett effect consisting of a fluxgate sensor, a high speed rotor with frequencies of up to 1.5 kHz, and a magnetic shield at room temperature. The effective magnetic field (Barnett field) in a sample arising from rotation magnetizes the sample and is proportional to the rotational frequency. The gyroscopic g factor, g ' , of rare earth metals, in particular, Gd, Tb, and Dy, was estimated to be 2.00 ± 0.08, 1.53 ± 0.17, and 1.15 ± 0.32, respectively, from the slopes of the rotation dependence of the Barnett field. This study provides a technique to determine the g ' factor even in samples where the spectroscopic method may not be available.

  16. Tuberculosis Facts - Testing for TB

    Science.gov (United States)

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

  17. Tuberculosis Facts - Exposure to TB

    Science.gov (United States)

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

  18. Electronic Structure of Rare-Earth Metals. II. Positron Annihilation

    DEFF Research Database (Denmark)

    Williams, R. W.; Mackintosh, Allan

    1968-01-01

    The angular correlation of the photons emitted when positrons annihilate with electrons has been studied in single crystals of the rare-earth metals Y, Gd, Tb, Dy, Ho, and Er, and in a single crystal of an equiatomic alloy of Ho and Er. A comparison of the results for Y with the calculations...... of Loucks shows that the independent-particle model gives a good first approximation to the angular distribution, although correlation effects probably smear out some of the structure. The angular distributions from the heavy rare-earth metals are very similar to that from Y and can be understood...... qualitatively in terms of the relativistic augmented-plane-wave calculations by Keeton and Loucks. The angular distributions in the c direction in the paramagnetic phases are characterized by a rapid drop at low angles followed by a hump, and these features are associated with rather flat regions of Fermi...

  19. Electronic and vibrational spectra of some rare earth trifluoromethanesulfonates crystals

    Science.gov (United States)

    Paul, P.; Ghosh, M.; Neogy, D.; Mallick, P. K.

    2011-01-01

    The Raman and infrared spectra of some rare earth (dysprosium and terbium) trifluoromethanesulfonates crystals have been analyzed. Different vibrational frequencies of trifluoromethanesulfonate ions (CF 3SO 3-) are identified and assigned to different vibrations of the SO 3 and CF 3 groups. Electronic transitions of R 3+ ions (R = Dy, Tb) in these salts have been assigned to transitions from the ground to different energy levels of the ground multiplet. The electronic energy levels of the rare earth ions are also determined theoretically with the help of single electron crystal field theory. They are found to yield results not only in good agreement with the observed spectral data but also in good conformity with those obtained previously from magnetic measurements.

  20. A Study of Heteropoly Complexes of Rare Earths as Catalyst Promoter in the Synthesis of Ethyl Acetate

    Institute of Scientific and Technical Information of China (English)

    Shui Yang HE; Ke PENG; Di ZHANG; Wang Ting WU; Gang Lin XUE; Qi Zhen SHI

    2004-01-01

    The capability of the synthesized heteropoly complexes of rare earths {K10 [(O39W11Si) Ln(Gly)3Ln(SiW11O39)]·9H2O (Ln=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy)} as the catalyst promoter in the synthesis of the ethyl acetate was studied. The results showed that the quantity of H2SO4 used for synthesizing the ethyl acetate can be reduced by 75% and the yield reached 98% at the optional condition.

  1. Rare earths (Ce, Eu, Tb) doped Y{sub 2}Si{sub 2}O{sub 7} phosphors for white LED

    Energy Technology Data Exchange (ETDEWEB)

    Sokolnicki, Jerzy, E-mail: jerzy.sokolnicki@chem.uni.wroc.pl [Faculty of Chemistry, University of Wroclaw, 14 F. Joliot-Curie Street, 50-383 Wroclaw (Poland)

    2013-02-15

    Nanocrystalline yttrium pyrosilicate Y{sub 2}Si{sub 2}O{sub 7} (YPS) singly, doubly or triply doped with Ce{sup 3+}, Eu{sup 3+}, Tb{sup 3+} was obtained by the reaction of nanostructured Y{sub 2}O{sub 3}:Ln{sup 3+} and colloidal SiO{sub 2} at high temperatures. X-ray diffraction analysis confirmed the formation of a single phase of {alpha}-YPS at 1200 Degree-Sign C. Two series of YPS samples doped with Eu{sup 3+} or Eu{sup 3+}/Tb{sup 3+} were obtained by applying the reducing atmosphere (75%N{sub 2}+25%H{sub 2}) at different temperatures. The luminescence and excitation spectra are reported. The singly Eu{sup 3+} doped YPS emit from both Eu{sup 3+} and Eu{sup 2+} ions, with the spectral position and width of the Eu{sup 2+} emission different in both series. The presence of Eu{sup 2+} in the samples was confirmed by electron paramagnetic resonance (EPR) spectra. A broadband emission of Eu{sup 2+} (380-650 nm), combined with the red emission of Eu{sup 3+} is perceived by the naked eye as white light. Co-doping of YPS:Eu{sup 3+} with Tb{sup 3+} results in enhancement of the green component of the emission, and well-balanced white luminescence. The colour of this emission is tunable, and it is possible to get Commission International de I'Eclairage (CIE) chromaticity coordinates of (0.327, 0.327), colour-rendering index (CRI) of 85, and quantum efficiency (QE) of 71%. These phosphors are efficiently excited in the wavelength range of 300-420 nm, which perfectly matches a near UV-emitting InGaN chip. It was shown that for triply (Ce{sup 3+}, Eu{sup 3+} and Tb{sup 3+}) doped samples the three emissions from the particular activators can be generated using one excitation wavelength. The white light resulting from the superposition of the blue (Ce{sup 3+}), green (Tb{sup 3+}) and red (Eu{sup 3+}) emissions can be obtained by varying the concentration of the active ions and the treating atmosphere, i.e. reducing or oxidising. Eu{sup 2+} was not detected in the triply

  2. Current situation and outlook of China rare earth industry (continued)%Current situation and outlook of China rare earth industry (continued)

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    China exported totally 16,900 tons of rare earths (physical quantity) during 2011, equivalent to 15,700 tons of rare earth oxide. Export value was USD 2.667 billion, with average unit export price of USD 169.9 per kilo. Price changes of rare earth products since January 2011 are reflected in Figure 2, 3 and 4, which show that the price rose rapidly since February, increased markedly after May, peaked in July and started to decline since then. There was not much change to the price of La and Ce products, but the price of didymium and Eu, Tb and Dy products that are in large demand changed significantly. Price in August of 2012 was about 30-40% of the highest price in 2011. Considering large increase of resource cost and environment cost, the price had been in a rational range.

  3. Evidence of Coulomb correction and spinorbit coupling in rare-earth dioxides CeO 2, PrO 2 and TbO 2: An ab initio study

    KAUST Repository

    Kanoun, Mohammed

    2012-04-01

    The current study investigates the structural, elastic, electronic and optical properties of CeO 2, PrO 2 and TbO 2 using the full potential (linearized) augmented plane wave plus local orbital method within the WuCohen generalized gradient approximation (GGA) with Hubbard (U) correction and spinorbit coupling (SOC). The GGAU implementation lead us to describe correctly the relativistic effect on 4f electrons for CeO 2. We clarify that the inclusion of the Hubbard U parameter and the spinorbit coupling are responsible for the ferromagnetic insulating of PrO 2 and TbO 2. The magnetic description is achieved by the spin-density contours and magnetic moment calculations, where we show the polarization of oxygen atoms from the rare earth atoms. The mechanical stability is shown via the elastic constants calculations. The optical properties, namely the dielectric function and the reflectivity are calculated for radiation up to 12 eV, giving interesting optoelectronic properties to these dioxides. © 2011 Elsevier B.V. All rights reserved.

  4. Phonon and crystal field excitations in geometrically frustrated rare earth titanates

    Science.gov (United States)

    Lummen, T. T. A.; Handayani, I. P.; Donker, M. C.; Fausti, D.; Dhalenne, G.; Berthet, P.; Revcolevschi, A.; van Loosdrecht, P. H. M.

    2008-06-01

    The phonon and crystal field excitations in several rare earth titanate pyrochlores are investigated. Magnetic measurements on single crystals of Gd2Ti2O7 , Tb2Ti2O7 , Dy2Ti2O7 , and Ho2Ti2O7 are used for characterization, while Raman spectroscopy and terahertz time domain spectroscopy are employed to probe the excitations in the materials. The lattice excitations are found to be analogous across the compounds over the whole temperature range investigated (295-4 K). The resulting full phononic characterization of the R2Ti2O7 pyrochlore structure is then used to identify crystal field excitations observed in the materials. Several crystal field excitations have been observed in Tb2Ti2O7 in Raman spectroscopy, among which all of the previously reported excitations. The presence of additional crystal field excitations, however, suggests the presence of two inequivalent Tb3+ sites in the low-temperature structure. Furthermore, the crystal field level at approximately 13cm-1 is found to be both Raman and dipole active, indicating broken inversion symmetry in the system and thus undermining its current symmetry interpretation. In addition, evidence is found for a significant crystal field-phonon coupling in Tb2Ti2O7 . The additional crystal field information on Tb2Ti2O7 adds to the recent discussion on the low temperature symmetry of this system and may serve to improve its theoretical understanding.

  5. Separation of Red(Y_2O_3:Eu~(3+)),Blue(BaMgAl_(10)O_(17):Eu~(2+))and Green(CeMgAl_(10)O_(17):Tb)Rare Earth Phosphors by Liquid/Liquid Extraction

    Institute of Scientific and Technical Information of China (English)

    MEI Guangjun; RAO Peng; Mitsuaki Matsuda; Toyohisa Fujita

    2009-01-01

    A novel process for separation of red(Y_2O_3:Eu~(3+)),blue(BaMgAl_(10)O_(17):Eu~(2+))and green(CeMgAl_(10)O_(17):Tb~3)rare earth fluorescent powders was proposed.At first,the blue powder can be extracted selectively from an aqueous solution using a chelating collector 2-thenoyltrifluoroacetone (TTA)dissolved in heptane at alkaline pH condition,then,chloroform was used for extracting the green powder into organic phase.The red phosphor remains in aqueous phase with potassium sodium tartrate depressant(PST).Therefore,three phosphors can be separated successfully from their artificial mixtures by liquid/liquid extraction,and grades and recovery of separated products reach respectively as follows:red is 96.9%and 95.2%,blue is 82.7%and 98.8%,green is 94.6%and 82.6%.

  6. Value analysis of neodymium content in shredder feed: toward enabling the feasibility of rare earth magnet recycling.

    Science.gov (United States)

    Bandara, H M Dhammika; Darcy, Julia W; Apelian, Diran; Emmert, Marion H

    2014-06-17

    In order to facilitate the development of recycling technologies for rare earth magnets from postconsumer products, we present herein an analysis of the neodymium (Nd) content in shredder scrap. This waste stream has been chosen on the basis of current business practices for the recycling of steel, aluminum, and copper from cars and household appliances, which contain significant amounts of rare earth magnets. Using approximations based on literature data, we have calculated the average Nd content in the ferrous shredder product stream to be between 0.13 and 0.29 kg per ton of ferrous scrap. A value analysis considering rare earth metal prices between 2002 and 2013 provides values between $1.32 and $145 per ton of ferrous scrap for this material, if recoverable as pure Nd metal. Furthermore, we present an analysis of the content and value of other rare earths (Pr, Dy, Tb).

  7. Find TB. Treat TB. Working together to eliminate TB.

    Centers for Disease Control (CDC) Podcasts

    2014-02-26

    In this podcast, Dr. Sundari Mase, Medical Team Lead in the Field Services and Evaluation Branch in the Division of Tuberculosis Elimination, discusses World TB Day and the 2014 theme.  Created: 2/26/2014 by National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (NCHHSTP).   Date Released: 2/26/2014.

  8. Switching the conductance of Dy nanocontacts by magnetostriction.

    Science.gov (United States)

    Müller, Marc; Montbrun, Richard; Marz, Michael; Fritsch, Veronika; Sürgers, Christoph; v Löhneysen, Hilbert

    2011-02-09

    The electrical conductance G of mechanical break-junctions fabricated from the rare-earth metal dysprosium has been investigated at 4.2 K where Dy is in the ferromagnetic state. In addition to the usual variation of the conductance while breaking the wire mechanically, the conductance can be changed reproducibly by variation of the magnetic field H, due to the large magnetostriction of Dy. For a number of contacts, we observe discrete changes in G(H) in the range of several G(0) = 2e(2)/h. The behavior of G(H) and its angular dependence can be quantitatively understood by taking into account the magnetostrictive properties of Dy. This realization of a magnetostrictive few-atom switch demonstrates the possibility of reproducibly tuning the conductance of magnetic nanocontacts by a magnetic field.

  9. Earth

    CERN Document Server

    Carter, Jason

    2017-01-01

    This curriculum-based, easy-to-follow book teaches young readers about Earth as one of the eight planets in our solar system in astronomical terms. With accessible text, it provides the fundamental information any student needs to begin their studies in astronomy, such as how Earth spins and revolves around the Sun, why it's uniquely suitable for life, its physical features, atmosphere, biosphere, moon, its past, future, and more. To enhance the learning experience, many of the images come directly from NASA. This straightforward title offers the fundamental information any student needs to sp

  10. Structural, spectral, dielectric and magnetic properties of Tb–Dy doped Li-Ni nano-ferrites synthesized via micro-emulsion route

    Energy Technology Data Exchange (ETDEWEB)

    Junaid, Muhammad, E-mail: junaid.malik95@yahoo.com [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Khan, Muhammad Azhar, E-mail: azhar.khan@iub.edu.pk [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Iqbal, F. [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Murtaza, Ghulam [Centre for Advanced Studies in Physics, Government College University, Lahore 54000 (Pakistan); Akhtar, Majid Niaz; Ahmad, Mukhtar [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Shakir, Imran [Deanship of scientific research, College of Engineering, King Saud University, PO Box 800, Riyadh 11421 (Saudi Arabia); Warsi, Muhammad Farooq [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan)

    2016-12-01

    Terbium (Tb) and dysprosium (Dy) doped lithium-nickel nano-sized ferrites (Li{sub 0.2}Ni{sub 0.8}Tb{sub 0.5x}Dy{sub 0.5x}Fe{sub 2−x}O{sub 4} where x=0.00−0.08) were prepared by micro-emulsion technique. The X-ray diffraction (XRD) patterns confirmed the single phase cubic spinel structure. The lattice constant was increased due to larger ionic radii of Tb{sup 3+} and Dy{sup 3+} cations. The crystallite size was found in the range 30–42 nm. The FTIR (Fourier transform infrared spectroscopy) spectra revealed two significant absorption bands (~400–600 cm{sup −1}) which indicate the formation of cubic spinel structure. The peaking behavior of dielectric parameters was observed beyond 1.5 GHz. The dielectric constant and dielectric loss were found to decrease by the increase of Tb–Dy contents and frequency. The doping of Tb and Dy in Li–Ni ferrites led to increase the coercive field (120–156 Oe). The smaller magnetic and dielectric parameters suggested the possible utility of these nano-materials in switching and microwave devices applications. - Highlights: • Li{sub 0.2}Ni{sub 0.8}Tb{sub 0.5x}Dy{sub 0.5x}Fe{sub 2-x}O{sub 4} ferrites were synthesized by micro-emulsion route. • Tb and Dy addition improves coercivity while decreased saturation magnetization. • These nanomaterials can be useful in microwave and switching devices applications.

  11. [Content of rare earth elements in wild Hypericum japonicum Thunb].

    Science.gov (United States)

    Wei, Zhen-Lin; Rui, Yu-Kui; Tian, Zhi-Huan

    2009-06-01

    Rare earth elements are important nutritional elements for human health, and today more and more attention has been paid to the effective components in Chinese traditional medicine, especially to rare earth elements. Fifteen rare earth elements in wild hypericum japonicum Thunb were analyzed by the methods of ICP-MS. The results showed that the concentrations of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Tm, Lu and Y ranged from 6 ng x g(-1) x DW to 14 522 ng x g(-1) x DW, and among them the concentrations of La, Ce and Nd were higher than 2 000 ng x g(-1) x DW. Compared with the concentration of rare earth elements in rice, corn, wheat and barley, the total concentration of rare earth elements in hypericum japonicum Thunb was much higher, which could be the mechanism of curative effect of hypericum japonicum Thunb on liverish diseases. The character of elements and the content of rare earth elements in soil should be responsible for the difference, but the distributive mechanism of rare earth elements in hypericum japonicum Thunb should be further studied.

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

    Science.gov (United States)

    Flood, D. J.

    1973-01-01

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

  13. HIV and Tuberculosis (TB)

    Science.gov (United States)

    ... AIDS-Related Opportunistic Infections and Coinfections HIV and Tuberculosis (TB) (Last updated 9/1/2016; last reviewed ... depends on a person’s individual circumstances. What is tuberculosis? Tuberculosis (TB) is a contagious disease that can ...

  14. Mycobacteria and TB

    National Research Council Canada - National Science Library

    Kaufmann, S. H. E. (Stephan H. E.); Hahn, Helmut

    2003-01-01

    .... Scientists investigating the epidemiology, immunology and molecular biology of TB or engaged in vaccine and drug development as well as physicians and social workers treating TB patients will benefit...

  15. Polytypic phase formation in DyAl sub 3 by rapid solidification

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Y.; Altounian, Z.; Muir, W.B. (Centre for the Physics of Materials and the Department of Physics, McGill University, 3600 University Street, Montreal, Quebec H3A 2T8, Canada (CA))

    1991-01-14

    Amorphous ribbons of Al{sub {ital x}}Dy{sub 100{minus}{ital x}}, 93{gt}{ital x}{gt}85, were obtained by melt spinning. During crystallization, in addition to Al, four different metastable crystalline phases of DyAl{sub 3} were observed. These phases are, in order of appearance, the high-pressure face-centered cubic phase, {gamma}-DyAl{sub 3} and three polytypic rhombohedral phases, {beta}-DyAl{sub 3}, {beta}{prime}-DyAl{sub 3}, and {alpha}{prime}-DyAl{sub 3}. It is the first time that the {beta}{prime} phase in rare-earth trialuminides and the {alpha}{prime} phase in Dy-Al alloy system have been observed. It is shown that all these phases are associated with the polytypic packing of the hexagonal DyAl{sub 3} atomic layers. The relative stability of the phases is found to be related to the hexagonal to cubic stacking ratio in the structure.

  16. Magnetostriction of Pseudobinary Compounds Pr0.15TbxDy0.85-xFe2 (x=0 to 0.85)

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The compound ingots of Pr0.15TbxDy0.85-xFe2 (x=0 to 0.85) were prepared by arc melting in a water Cu boat using arc furnace under a purified Ar atmosphere. Appropriate annealing (850℃, 100 h) can obtain single Laves phase compound. The magnetostriction for these systems will rise obviously when partially substituted Tb or Dy by Pr.

  17. Phase structure and magnetocaloric effect of (Tb1-xDyx)Co2 alloys

    Institute of Scientific and Technical Information of China (English)

    ZHUANG Yinghong; CHEN Xiang; ZHOU Kaiwen; LI Kefeng; MA Chunhua

    2008-01-01

    Phase structure and magnetocaloric effect of (Tb1-xDyx)Co2 alloys with x=0, 0.2, 0.4, 0.6, 0.8, and 1.0 were investigated using X-ray diffraction analysis, differential thermal analysis, and magnetization measurement. The samples were single phase with cubic MgCu2- type structure; with the increase of Dy content, Tc decreased from 240 K (TbCo2) to 130 K (DyCo2), and the maximum magnetic entropy change |ΔSM,max| increased from 3.133 to 8.176 J/kg-K under low magnetic field of 0-2 T. The Arrott plot and the change of |ΔSM,max| showed that magnetic phase transition from second order to first order occurred with the increase of Dy content between x=0.6 and 0.8.

  18. Prospective analysis of the flows of certain rare earths in Europe at the 2020 horizon.

    Science.gov (United States)

    Rollat, Alain; Guyonnet, Dominique; Planchon, Mariane; Tuduri, Johann

    2016-03-01

    This paper proposes a forecast of certain rare earth flows in Europe at the 2020 horizon, based on an analysis of trends influencing various actors of the rare earth industry along the value chain. While 2020 is indicated as the forecast horizon, the analysis should be considered as more representative of the next decade. The rare earths considered here are used in applications that are important for a low-carbon energy transition and/or have a significant recycling potential: NdFeB magnets (Pr, Nd, Dy), NiMH batteries (Pr, Nd) and fluorescent lamp phosphors (Eu, Tb, Y). An analysis of major trends affecting the rare earth industry in Europe along the value chain (including extraction, separation, fabrication, manufacture, use and recycling), helps to build a scenario for a material flow analysis of these rare earths in Europe. The scenario assumes in particular that during the next decade, there exists a rare earth mine in production in Europe (with Norra Kärr in Sweden as a most likely candidate) and also that recycling is in line with targets proposed in recent European legislation. Results are presented in the form of Sankey diagrams which help visualize the various flows for the three applications. For example, calculations forecast flows from extraction to separation of Pr, Nd and Dy for magnet applications in Europe, on the order of 310 tons, 980 tons and 80 tons rare earth metal resp., while recycled flows are 35 tons, 110 tons and 30 tons resp. Calculations illustrate how the relative contribution of recycling to supply strongly depends on the situation with respect to demand. Considering the balance between supply and demand, it is not anticipated any significant shortage of rare earth supply in Europe at the 2020 horizon, barring any new geopolitical crisis involving China. For some heavy rare earths, supply will in fact largely outweigh demand, as for example Europium due to the phasing out of fluorescent lights by LEDs.

  19. Synthesis and spectral characterization of lanthanide complexes with 1, 2-diphenyl-4-butyl-3,5-pyrazolidinedione: Luminescent property of Tb(Ⅲ) complex

    Institute of Scientific and Technical Information of China (English)

    M.R. Anoop; P.S. Binil; S. Suma; M.R. Sudarsanakumar

    2012-01-01

    The complexes of rare earth elements with 1,2-diphenyl-4-butyl-3,5-Pyrazolidinedione (PBH,phenylbutazone) were synthesized and characterized byelemental analysis,molar conductance,IR,UV-Vis,EPR and magnetic moment measurements.Based on these studies the complexes were formulated as [Ln(PB)3(H2O)2]·nH2O,where Ln=Eu(Ⅲ),Gd(Ⅲ),Tb(Ⅲ),Dy(Ⅲ) and Er(Ⅲ).From IR spectra,it was found that PBH acted as a bidentate mono-ionic ligand coordinating through two carbonyl oxygen of the pyrazolidinedione ring.The thermal analysis of all the complexes was carried out at a heating rate of 10 ℃/min.The kinetic aspects of the complexes were evaluated.The negative entropy value of the complexes indicated a more ordered state for the activated complexes.The photoluminescence property of Tb(Ⅲ) complex was investigated.It showed all the characteristic emission peaks of Tb3+ with a life time of 0.98914 ms.

  20. Extraordinarily large intrinsic magnetodielectric coupling of the Tb member within the Haldane spin-chain family R2BaNiO5

    Science.gov (United States)

    Upadhyay, Sanjay Kumar; Paulose, P. L.; Sampathkumaran, E. V.

    2017-07-01

    The Haldane spin-chain compound Tb2BaNiO5 has been known to order antiferromagnetically below (TN= )63 K . The present magnetic studies on the polycrystals bring out that there is another magnetic transition at a lower temperature (T2=)25 K with pronounced magnetic-field-induced metamagnetic and metaelectric behaviors. Multiferroic features are found below T2 only and not at TN. The most intriguing observation is that the observed change in dielectric constant (Δɛ') is intrinsic and largest (e.g., ˜18% at 15 K) within this Haldane spin-chain family R2BaNiO5 . Taking into account the fact that this trend (that is, the largest value of Δɛ' for the Tb case within this family) correlates well with a similar trend in TN (with the values of TN being ˜55, 58, 53, and 32 K for Gd, Dy, Ho, and Er cases), we believe that the explanation usually offered for this TN behavior in rare-earth systems is applicable for this Δɛ' behavior as well. That is, single-ion anisotropy following crystal-field splitting is responsible for the extraordinary magnetodielectric effect in this Tb case. This work provides a pathway in the field of multiferroics to promote magnetoelectric coupling.

  1. Structural and mechanical stability of rare-earth diborides

    Institute of Scientific and Technical Information of China (English)

    Haci Ozisik; Engin Deligoz; Kemal Colakoglu; Gokhan Surucu

    2013-01-01

    Structural and mechanical properties of several rare-earth diborides were systematically investigated by first principles calculations.Specifically,we studied XB2,where X =Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm,and Lu in the hexagonal A1B2,ReB2,and orthorhombic OsB2-type structures.The lattice parameters,bulk modulus,bond distances,second order elastic constants,and related polycrystalline elastic moduli (e.g.,shear modulus,Young's modulus,Poisson's ratio,Debye temperature,sound velocities) were calculated.Our results indicate that these compounds are mechanically stable in the considered structures,and according to "Chen's method",the predicted Vickers hardness shows that they are hard materials in A1B2-and OsB2-type structures.

  2. Role of some rare earth (RE) ions (RE = La, Pr, Nd, Sm, Gd and Dy) in crystal and mechanical behaviours of sol–gel derived ZrO2–2 mol% RE2O3 spun fibres calcined at 1300°C

    Indian Academy of Sciences (India)

    M K Naskar; M Chatterjee; D Ganguli

    2002-10-01

    Crystal behaviours such as crystallization temperature (amorphous to tetragonal () zirconia), tendency of phase transformation (tetragonal to monoclinic () zirconia) and lattice strain were studied with mechanical property e.g. tensile strength of sol–gel derived ZrO2–2 mol% RE2O3 (RE = La, Pr, Nd, Sm, Gd and Dy) spun fibres. Rare earth cations of varying sizes played a significant role in changing the above mentioned properties of ZrO2–2 mol% RE2O3 fibres. It was found that with decreasing the ionic size difference between the zirconium and RE ions, crystallization temperature (amorphous $\\rightarrow \\ t$-ZrO2) decreased, the probability of phase transformation ($t \\rightarrow m$) decreased, lattice strain which is related to lattice distortion decreased and tensile strength increased.

  3. Rare earth complexes with a novel ligand N-(naphthalen-2-yl)- N-phenyl-2-(quinolin-8-yloxy)acetamide: Preparation and spectroscopic studies

    Science.gov (United States)

    Wu, Wei-Na; Tang, Ning; Yan, Lan

    2008-12-01

    Six complexes of rare earth nitrates (Ln = La, Sm, Eu, Gd, Tb, Dy) with a new amide type ligand, N-(naphthalen-2-yl)- N-phenyl-2-(quinolin-8-yloxy)acetamide (L) have been prepared and characterized by elemental analysis, conductivity measurements, IR and and 1H NMR spectra. Under excitation, Eu(III) and Sm(III) complexes exhibited strong red emissions. And the luminescence intensity of Sm(III) complex is higher than that of Eu(III) complex. Thus the Eu(III) and Sm(III) complexes are the potential light conversion agent. However, the Tb(III) and Dy(III) complexes cannot exhibit characteristic emissions of terbium and dysprosium ions, respectively. The results of phosphorescence spectrum show that the triplet-state energy level of the ligand matches better to the resonance level of Eu(III) than Tb(III) ion. In addition, the luminescence of the Eu(III) complex is also relatively strong in highly diluted tetrahydrofuran solution (2 × 10 -4 mol/L) compared with the powder. This is not only due to the solvate effects but also to the changes of the structure of the Eu(III) complex after being dissolved into the solvents. Furthermore, owing to the co-luminescence effect, the proper La(III) or Gd(III) doped Eu(III) complexes show stronger luminescence than the pure Eu(III) complex.

  4. Synthesis, Characterization and Bioactivity of Complexes of Rare Earth with Bis-Schiff Base from Furoylpyrazolone

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Eleven new complexes of rare earths with bis-Schiff base derived from N,N'-bis[(1-phenyl-3-methyl-5-oxo-4-pyrazolinyl)α-furylmethylidyne] ethylenediimine ((HPMαFP)2en) were synthesized. On the basis of elemental analysis and molar conductance, a general formula of the complexes, [RE(HPMαFP)2 en(NO3)2]NO3 (RE=La, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Yb,Y), was given. The complexes were characterized by IR, UV-visible, 1H NMR, 13C NMR and fluorescence. The results show that the bis-Schiff base is a quadridentate ligand and the rare earth ions exhibit coordination of eight in the complexes. The antibacterial experiments indicate that they have high antibacterial activities against S. aureus, B. subtillis, E. coli, E.carotovora, C. flaccumfaciens.

  5. Capillary-force-induced formation of luminescent polystyrene/(rare-earth-doped nanoparticle) hybrid hollow spheres.

    Science.gov (United States)

    Chen, Min; Xie, Lin; Li, Fuyou; Zhou, Shuxue; Wu, Limin

    2010-10-01

    This paper presents a "one-pot" procedure to synthesize polystyrene/(rare-earth-doped nanoparticles) (PS/REDNPs) hybrid hollow spheres via the in situ diffusion of organic core into inorganic shell under strong capillary force. In this approach, when carboxyl-capped PS colloids were deposited by different REDNPs in aqueous medium, such as LaF3:Eu3+, LaF3:Ce3+-Tb3+, and YVO4:Dy3+, PS/REDNPs inorganic-organic hybrid hollow spheres could be directly obtained via the in situ diffusion of core PS chains into the voids between rare-earth-doped nanoparticles through the strong capillary force. Not only is the synthetic procedure versatile and very simple, but also the obtained hybrid hollow spheres are hydrophilic and luminescent and could be directly used in chemical and biological fields.

  6. Ternary rare-earth based alternative gate-dielectrics for future integration in MOSFETs

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, Juergen; Lopes, Joao Marcelo; Durgun Oezben, Eylem; Luptak, Roman; Lenk, Steffi; Zander, Willi; Roeckerath, Martin [IBN 1-IT, Forschungszentrum Juelich, 52425 Juelich (Germany)

    2009-07-01

    The dielectric SiO{sub 2} has been the key to the tremendous improvements in Si-based metal-oxide-semiconductor (MOS) device performance over the past four decades. It has, however, reached its limit in terms of scaling since it exhibits a leakage current density higher than 1 A/cm{sup 2} and does not retain its intrinsic physical properties at thicknesses below 1.5 nm. In order to overcome these problems and keep Moore's law ongoing, the use of higher dielectric constant (k) gate oxides has been suggested. These high-k materials must satisfy numerous requirements such as the high k, low leakage currents, suitable band gap und offsets to silicon. Rare-earth based dielectrics are promising materials which fulfill these needs. We will review the properties of REScO{sub 3} (RE = La, Dy, Gd, Sm, Tb) and LaLuO{sub 3} thin films, grown with pulsed laser deposition, e-gun evaporation or molecular beam deposition, integrated in capacitors and transistors. A k > 20 for the REScO{sub 3} (RE = Dy, Gd) and around 30 for (RE = La, Sm, Tb) and LaLuO{sub 3} are obtained. Transistors prepared on SOI and sSOI show mobility values up to 380 cm{sup 2}/Vs on sSOI, which are comparable to such prepared with HfO{sub 2}.

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

    Science.gov (United States)

    ... the Facts Tuberculosis - The Connection between TB and HIV 12-Dose Regimen for Latent TB Infection-Patient Education Brochure Posters Mantoux Tuberculin Skin Test Wall Chart World TB Day Think TB Stop TB Reports & Articles Morbidity and Mortality Weekly Reports (MMWRs) DTBE Authored ...

  8. Temperature and magnetic field induced multiple magnetic transitions in DyAg(2).

    Science.gov (United States)

    Arora, Parul; Chattopadhyay, M K; Sharath Chandra, L S; Sharma, V K; Roy, S B

    2011-02-09

    The magnetic properties of the rare-earth intermetallic compound DyAg(2) are studied in detail with the help of magnetization and heat capacity measurements. It is shown that the multiple magnetic phase transitions can be induced in DyAg(2) both by temperature and magnetic field. The detailed magnetic phase diagram of DyAg(2) is determined experimentally. It was already known that DyAg(2) undergoes an incommensurate to commensurate antiferromagnetic phase transition close to 10 K. The present experimental results highlight the first order nature of this phase transition, and show that this transition can be induced by magnetic field as well. It is further shown that another isothermal magnetic field induced transition or metamagnetic transition exhibited by DyAg(2) at still lower temperatures is also of first order nature. The multiple magnetic phase transitions in DyAg(2) give rise to large peaks in the temperature dependence of the heat capacity below 17 K, which indicates its potential as a magnetic regenerator material for cryocooler related applications. In addition it is found that because of the presence of the temperature and field induced magnetic phase transitions, and because of short range magnetic correlations deep inside the paramagnetic regime, DyAg(2) exhibits a fairly large magnetocaloric effect over a wide temperature window, e.g., between 10 and 60 K.

  9. Studies on extracting solutions of endohedral rare-earth metallofullerenes by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

    Institute of Scientific and Technical Information of China (English)

    孙大勇; 刘志强; 刘子阳; 郭兴华; 徐文国; 刘淑莹

    1997-01-01

    Thirteen extracting solutions of rare-earth metallofullerenes containing La,Ce,Pr,Nd Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm and Yb respectively have been investigated by means of matrix-assisted laser desorpuon/ ionization time-of-flight mass spectrometry.The influences of the positive-ion/negative-ion mode,laser intensity,ma trix and mass discrimination to the analytical results are studied,based on which the optimal analytical conditions have been determined.The results show that the extracting solutions contain large quantities of rare-earth metallofullerenes besides empty fullerenes.On the basis of comparing their relative intensities,the different structure stabilities and solubilities of metallofullerenes with different rare-earth metals encapsulated into the fullerene cages,as well as some possible reasons to those differences,are discussed.

  10. TB in Captive Elephants

    Centers for Disease Control (CDC) Podcasts

    2017-04-27

    Dr. Barry Kreiswirth, founding director of the Public Health Research Institute, TB Center, at Rutgers University, discusses TB in three captive elephants.  Created: 4/27/2017 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 4/27/2017.

  11. Blue–green afterglow of BaAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Bao-gai [School of Mathematics and Physics, Changzhou University, Jiangsu 213164 (China); Ma, Qing-lan [School of Mathematics and Physics, Changzhou University, Jiangsu 213164 (China); School of Electronics and Information, Nantong University, Jiangsu 226019 (China); Xiong, Rui [School of Physics and Technology, Wuhan University, Hubei 430072 (China); Li, Xiazhang [Analysis and Testing Center, Changzhou University, Jiangsu 213164 (China); Huang, Yuan Ming, E-mail: dongshanisland@126.com [School of Mathematics and Physics, Changzhou University, Jiangsu 213164 (China)

    2016-03-15

    Highlights: • Afterglow can be achieved when Eu{sup 2+} is absent in the DyAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors. • The afterglow of DyAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors is discernible to naked eyes for minutes. • Dy{sup 3+} introduced trap centers are believed to be responsible for the afterglow. - Abstract: Dy{sup 3+} doped barium aluminate (BaAl{sub 2}O{sub 4}:Dy{sup 3+}) phosphors were prepared via the sol–gel combustion route at the ignition temperature of 600 °C. The phosphors were characterized with X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, photoluminescence spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Regardless of the absence of Eu{sup 2+} luminescent centers, broadband blue–green afterglow with its peak at about 490 nm was recorded in the BaAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors. The decay profile of the blue–green afterglow can be best fitted into a two-component exponential function with the two lifetime decay constants to be 8.81 and 45.25 s, respectively. The observation of blue–green afterglow from BaAl{sub 2}O{sub 4}:Dy{sup 3+} in the absence of Eu{sup 2+} provides unique opportunity in unveiling the afterglow mechanisms of rare-earth doped alkaline-metal aluminates. Possible mechanisms on the blue–green afterglow in BaAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors are discussed in terms of the Dy{sup 3+} ions introduced trap centers as well as luminescent centers in the crystal lattice.

  12. Magnetic rare earth superlattices

    DEFF Research Database (Denmark)

    Majkrzak, C.F.; Kwo, J.; Hong, M.;

    1991-01-01

    Advances in molecular beam epitaxy deposition techniques have recently made it possible to grow, an atomic plane at a time, single crystalline superlattices composed of alternating layers of a magnetic rare earth, such as Gd, Dy, Ho, or Er, and metallic Y, which has an identical chemical structure...

  13. Assembly, crystal structure, and luminescent properties of three-dimensional (10,3)-a netted rare earth coordination polymers

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Solid complexes [REL(NO3)3]n with novel (10,3)-a type three-dimensional networks structure have been assembled using rare earth nitrates and an amide type semirigid tripodal bridging ligand, 1,3,5-tris {[(2′-benzylaminoformyl)phenoxyl]methyl}benzene (L), as building blocks. The complexes were crys- tallized in the orthorhombic system with chiral space group P212121. The whole structure consists of an infinite array of trigonal RE(III) ions bridged by tridentate ligands, and a novel (10,3)-a net is formed, which is very uncommon in the rare earth complexes. At room temperature, the Sm(III), Eu(III), Tb(III), Dy(III) complexes all exhibited characteristic luminescence emissions of central metal ions under UV light excitation.

  14. Magnetic nanosized rare earth iron garnets R3Fe5O12: Sol-gel fabrication, characterization and reinspection

    Science.gov (United States)

    Opuchovic, Olga; Kareiva, Aivaras; Mazeika, Kestutis; Baltrunas, Dalis

    2017-01-01

    The magnetic nanosized rare earth iron garnets (R3Fe5O12, where R=Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were prepared by an aqueous sol-gel method. Herein we present, that all these garnets can be obtained by this effective synthesis method simply by changing the temperature of the final annealing. It was also demonstrated, that a different annealing temperature leads to a different particle size distribution of the final product. The SEM analysis results revealed that the smallest particles were formed in the range of 75-130 nm. The phase purity and structure of the rare earth iron garnets were estimated using XRD analysis and Mössbauer spectroscopy. Magnetic properties were determined by magnetization measurements. The relation between the particle size, composition and magnetic properties of the sol-gel derived garnets were also discussed in this study.

  15. A density functional theory study of electronic and magnetic properties of rare earth doped monolayered molybdenum disulphide

    Science.gov (United States)

    Majid, Abdul; Imtiaz, Anum; Yoshiya, Masato

    2016-10-01

    The effects of Rare Earth (RE) atoms Sm, Eu, Gd, Tb, and Dy doping on structural, electronic, and magnetic properties of single layer MoS2 were investigated using first principles calculations. The analysis of electronic properties pointed out the appearance of host-impurity hybrid states on the edges of principal bands of the material, which appeared to cause narrowing of its bandgap. The values of total magnetic moment were calculated as 3.3 μB, 8.1 μB, 8.5 μB, 6.8 μB, and 6.4 μB for Sm-, Eu-, Gd-, Tb-, and Dy-doped MoS2, respectively. The underestimation of magnetic moment in the case of Sm doping is found which is assigned to shielding of 4f moments and quenching of angular momentum caused by Sm 4f-S 3p hybridization. On the other hand, the observed overestimation of magnetic moments for Eu and Gd cases is likely to be due to increase in angular momentum due to indirect exchange interaction of highly localized 4f states via 5d or 6s conduction electrons. The findings of this work point out the possibilities of tuning the band gap and magnetic properties of monolayer MoS2 upon RE doping for realization of p-type ferromagnetic semiconductors.

  16. Calculations of the magnetic entropy change in amorphous through a microscopic anisotropic model: Applications to Dy{sub 70}Zr{sub 30} and DyCo{sub 3.4} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ranke, P. J. von, E-mail: von.ranke@uol.com.br; Nóbrega, E. P.; Ribeiro, P. O.; Alvarenga, T. S. T.; Lopes, P. H. O.; Sousa, V. S. R. de; Oliveira, N. A. de [Instituto de Física, Universidade do Estado do Rio de Janeiro—UERJ, Rua São Francisco Xavier, 524, 20550-013 Rio de Janeiro (Brazil); Caldas, A. [Sociedade Unificada de Ensino Superior e Cultura, SUESC, 20211-351 Rio de Janeiro (Brazil); Alho, B. P. [Instituto de Aplicação Fernando Rodrigues da Silveira, Universidade do Estado do Rio de Janeiro, Rua Santa Alexandrina, 288, 20260-232 Rio de Janeiro (Brazil); Carvalho, G. [Laboratório Nacional de Luz Sincroton—LNLS, 13083-970 Campinas, São Paulo (Brazil); Magnus, A.

    2014-10-14

    We report theoretical investigations on the magnetocaloric effect, described by the magnetic entropy change in rare earth—transition metal amorphous systems. The model includes the local anisotropy on the rare earth ions in Harris-Plischke-Zuckermann assumptions. The transition metals ions are treated in terms of itinerant electron ferromagnetism and the magnetic moment of rare earth ions is coupled to the polarized d-band by a local exchange interaction. The magnetocaloric effect was calculated in DyCo{sub 3.4} system, which presents amorphous sperimagnetic configuration. The calculations predict higher refrigerant capacity in the amorphous DyCo{sub 3.4} than in DyCo{sub 2} crystal, highlighting the importance of amorphous magnetocaloric materials. Our calculation of the magnetocaloric effect in Dy{sub 70}Zr{sub 30}, which presents amorphous asperomagnetic configuration, is in good agreement with the experimental result. Furthermore, magnetic entropy changes associated with crystal-amorphous configurations change are estimated.

  17. Kinetic studies show that Ca2+ and Tb3+ have different binding preferences toward the four Ca2+-binding sites of calmodulin.

    Science.gov (United States)

    Wang, C L; Leavis, P C; Gergely, J

    1984-12-18

    The stepwise addition of Tb3+ to calmodulin yields a large tyrosine-sensitized Tb3+ luminescence enhancement as the third and fourth ions bind to the protein [Wang, C.-L. A., Aquaron, R. R., Leavis, P. C., & Gergely, J. (1982) Eur. J. Biochem. 124, 7-12]. Since the only tyrosine residues in calmodulin are located within binding sites III and IV, these results suggest that Tb3+ binds first to sites I and II. Recent NMR studies have provided evidence that Ca2+, on the other hand, binds preferentially to sites III and IV. Kinetic studies using a stopped-flow apparatus also show that the preferential binding of Ca2+ and lanthanide ions is different. Upon rapid mixing of 2Ca-calmodulin with two Tb3+ ions, there was a small and rapid tyrosine fluorescence change, but no Tb3+ luminescence was observed, indicating that Tb3+ binds to sites I and II but not sites III and IV. When two Tb3+ ions are mixed with 2Dy-calmodulin, Tb3+ luminescence rises rapidly as Tb3+ binds to the empty sites III and IV, followed by a more gradual decrease (k = 0.4 s-1 as the ions redistribute themselves over the four sites. These results indicate that (i) both Tb3+ and Dy3+ prefer binding to sites I and II of calmodulin and (ii) the binding of Tb3+ to calmodulin is not impeded by the presence of two Ca2+ ions initially bound to the protein. Thus, the Ca2+ and lanthanide ions must exhibit opposite preferences for the four sites of calmodulin: sites III and IV are the high-affinity sites for Ca2+, whereas Tb3+ and Dy3+ prefer sites I and II.

  18. Tuberculosis Facts - TB and HIV/AIDS

    Science.gov (United States)

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

  19. Syntheses, Characterization and Crystal Structure of Rare Earth(Y,Dy) Complexes with β-Alanine%稀土(钇、镝)与β-丙氨酸配合物的合成、表征及晶体结构

    Institute of Scientific and Technical Information of China (English)

    马录芳; 梁福沛; 王利亚; 胡瑞祥

    2004-01-01

    合成了Y和Dy与β-丙氨酸的配合物,并测定了其晶体结构,配合物组成为{[Ln2(β-ala)6(H2O)4](ClO4)6·H2O}n(Ln=Y(1)\\,Dy(2)),配合物均属于三斜晶系,P1空间群,晶胞参数为:(1):a=1.2903(3)nm,b=2.1667(4)nm,c=0.92100(18)nm,α=98.73(3)°,β=97.02(3)°,γ=76.89(3)°,V=2.4683(3)nm3,Z=2,Dc=1.881mg·m-3;(2):a=0.9222(2)nm,b=1.2875(3)nm,c=2.1634(5)nm,α=77.01(2)°,β=81.21(2)°,γ=82.89(2)°,V=2.4629(10)nm3,Z=2,Dc=2.082mg·m-3,两个配合物具有类似的晶体结构,均为无限链状分子,Ln(Ⅲ)离子为九配位的单帽四方反棱柱配位多面体.

  20. First-principles calculation of crystal field parameters of Dy ions substituted for Nd in Nd-Fe-B magnets

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, S; Moriya, H; Tsuchiura, H; Sakuma, A [Department of Applied Physics, Tohoku University, Sendai 980-8579 (Japan); Divis, M [Department of Condensed Matter, Charles University, FMF, Prague (Czech Republic); Novak, P, E-mail: tanaka@olive.apph.tohoku.ac.jp [Institute of Physics of ASCR, Cukrovarnicka 10, 162 53 Prague 6 (Czech Republic)

    2011-01-01

    We study the electronic structures of crystalline Nd{sub 2}Fe{sub 14}B, Dy{sub 2}Fe{sub 14}B and Dy-doped Nd-Fe-B, and estimate the crystal field parameter A{sup 0}{sub 2}(r{sup 2}) of the rare earth ions of these systems based on the first principles calculations. We find that the crystal field of the Dy ions is appreciably insensitive to its crystallographic location than that of Nd ions.

  1. Questions and Answers about TB

    Science.gov (United States)

    ... GIT) and T-Spot ® . TB test. TB disease – an illness in which TB bacteria are multiplying and attacking a part of the body, usually the lungs. The symptoms of TB disease include weakness, weight loss, fever, no appetite, chills, ...

  2. Tuberculosis (TB): Treatment

    Science.gov (United States)

    ... Education & Training Home Conditions Tuberculosis (TB) Tuberculosis: Treatment Tuberculosis: Treatment Make an Appointment Refer a Patient Ask ... or bones is treated longer. NEXT: Preventive Treatment Tuberculosis: Diagnosis Tuberculosis: History Clinical Trials For more than ...

  3. Japanese Rare Earth Market

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Since China cancelled export rebate in May this year,prices of magnetic materials related rare earth productscontinuously rose. Increasing production cost is largelyattributed to investment in environmental protectionequipments. Prices of Nd and Dy metals rose 20~30% over thebeginning of this year.Price of Nd was USD 11.5 - 12/Kg from USD 9/Kg at theend of 2004, up 30%. Price of Dy rose to USD 65- 70/Kg fromUSD 50/Kg early this year, up 20%. Price of Pr climbed to USD13.5 - 14/Kg from USD 11/Kg, up 30%. Pri...

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

    Science.gov (United States)

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

    2010-09-06

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

  5. HIV-Associated TB: Facts 2013

    Science.gov (United States)

    ... drug-resistant TB such as multi-drug resistant (MDR-TB) and extensively drug resistant TB (XDR-TB). COLLABORATIVE ... design and costing of expanded TB/HIV and MDR-TB components within the Stop TB Partnership' s Global Plan ...

  6. Tuberculosis Facts - TB Can Be Treated

    Science.gov (United States)

    Tuberculosis (TB) Facts TB Can Be Treated What is TB? “TB” is short for a disease called tuberculosis. TB is spread through the air from one ... Viral Hepatitis, STD, and TB Prevention Division of Tuberculosis Elimination Page 1 of 2 TB Facts: TB ...

  7. Tuberculosis Facts - You Can Prevent TB

    Science.gov (United States)

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

  8. New reversed phase-high performance liquid chromatographic method for selective separation of yttrium from all rare earth elements employing nitrilotriacetate complexes in anion exchange mode.

    Science.gov (United States)

    Dybczyński, Rajmund S; Kulisa, Krzysztof; Pyszynska, Marta; Bojanowska-Czajka, Anna

    2015-03-20

    Separation of Y from other rare earth elements (REE) is difficult because of similarity of its ionic radius to ionic radii of Tb, Dy and Ho. In the new RP-HPLC system with C18 column, tetra-n-butyl ammonium hydroxide (TBAOH) as an ion interaction reagent (IIR), nitrilotriacetic acid (NTA) as a complexing agent at pH=2.8-3.5, and post column derivatization with Arsenazo III, yttrium is eluted in the region of light REE, between Nd and Sm and is base line separated from Nd and Sm and even from promethium. Simple model employing literature data on complex formation of REE with NTA and based on anion exchange mechanism was developed to foresee the order of elution of individual REE. The model correctly predicted that lanthanides up to Tb will be eluted in the order of increasing Atomic Number (At.No.) but all heavier REE will show smaller retention factors than Tb. Concurrent UV/VIS detection at 658nm and the use of radioactive tracers together with γ-ray spectrometric measurements made possible to establish an unique elution order of elution of REE: La, Ce, Pr, Nd, Pm, Y, Sm, Er, Ho, Tm, Yb, Eu, Lu, Dy+Gd, Tb, Sc. The real place of Y however, in this elution series differs from that predicted by the model (Y between Sm and Eu). The method described in this work enables selective separation of Y from La, Ce, Pr, Nd, Pm, Sm and all heavier REE treated as a group.

  9. Acoustic investigations on PbO–Al2O3–B2O3 glasses doped with certain rare earth ions

    Indian Academy of Sciences (India)

    M Rami Reddy; S Bangaru Raju; N Veeraiah

    2001-02-01

    Elastic moduli (, ), Poisson’s ratio (), microhardness () and some thermodynamical parameters such as Debye temperature (), diffusion constant (), latent heat of melting ( ) etc of PbO–Al2O3–B2O3 glasses doped with rare earth ions viz. Pr3+, Nd3+, Sm3+, Eu3+, Tb3+, Dy3+, Ho3+, Er3+ and Yb3+, are studied as functions of temperatures (in the temperature range 30–200°C) by ultrasonic techniques. All these parameters are found to increase with increasing atomic number of the rare earth ions and found to decrease with increasing temperature of measurement. From these results (together with IR spectra of these glasses), an attempt is made to throw some light on the mechanical strength of these glasses.

  10. Measurement of cross sections producing short-lived nuclei by 14 MeV neutron. Br, Te, Dy, Ho, Yb

    Energy Technology Data Exchange (ETDEWEB)

    Sakane, H.; Matsumoto, T.; Yamamoto, H.; Kawade, K. [Nagoya Univ. (Japan); Iida, T.; Takahashi, A.

    1997-03-01

    Nine neutron activation cross sections producing the nuclei with half-lives between 2 min and 57 min have been measured at energy range between 13.4 and 14.9 MeV for Br, Te, Dy, Ho, Yb. The cross sections of {sup 81}Br(n,p){sup 81m}Se, {sup 128}Te(n,p){sup 128m}Sb, {sup 128}Te(n,{alpha}){sup 125m}Sn, {sup 164}Dy(n,p){sup 164}Tb, {sup 165}Ho(n,{alpha}){sup 162}Tb, {sup 176}Yb(n,p){sup 176}Tm were newly obtained at the six energy points between 13.4-14.9 MeV, although the previous results have been obtained at one energy point. {sup 79}Br(n,2n){sup 78}Br, {sup 164}Dy(n,p){sup 164}Tb are compared with evaluated data of JENDL-3.2. The evaluations for these reactions agree reasonably well with experimental results. The cross sections of (n,p) reaction are compared with systematics by Kasugai et. al. The systematics agrees with experimental results. (author)

  11. A binuclear Fe(III)Dy(III) single molecule magnet. Quantum effects and models.

    Science.gov (United States)

    Ferbinteanu, Marilena; Kajiwara, Takashi; Choi, Kwang-Yong; Nojiri, Hiroyuki; Nakamoto, Akio; Kojima, Norimichi; Cimpoesu, Fanica; Fujimura, Yuichi; Takaishi, Shinya; Yamashita, Masahiro

    2006-07-19

    The binuclear [FeIII(bpca)(mu-bpca)Dy(NO3)4], having Single Molecule Magnet (SMM) properties, belonging to a series of isostructural FeIIILnIII complexes (Ln = Eu, Gd, Tb, Dy, Ho) and closely related FeIILnIII chain structures, was characterized in concise experimental and theoretical respects. The low temperature magnetization data showed hysteresis and tunneling. The anomalous temperature dependence of Mössbauer spectra is related to the onset of magnetic order, consistent with the magnetization relaxation time scale resulting from AC susceptibility measurements. The advanced ab initio calculations (CASSCF and spin-orbit) revealed the interplay of ligand field, spin-orbit, and exchange effects and probed the effective Ising nature of the lowest states, involved in the SMM and tunneling effects.

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

    Science.gov (United States)

    Liu, Xiaoyang; Fleet, Michael E.

    2002-11-01

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

  13. Nuclear Level Density of ${}^{161}$Dy in the Shell Model Monte Carlo Method

    CERN Document Server

    Özen, Cem; Nakada, Hitoshi

    2012-01-01

    We extend the shell-model Monte Carlo applications to the rare-earth region to include the odd-even nucleus ${}^{161}$Dy. The projection on an odd number of particles leads to a sign problem at low temperatures making it impractical to extract the ground-state energy in direct calculations. We use level counting data at low energies and neutron resonance data to extract the shell model ground-state energy to good precision. We then calculate the level density of ${}^{161}$Dy and find it in very good agreement with the level density extracted from experimental data.

  14. Magnetic and Transport Properties of Ferromagnetic Semiconductor GaDyN Thin Film

    Institute of Scientific and Technical Information of China (English)

    LI Xi-Jun; ZHOU YI-Kai; KIM M.; KIMURA S.; TERAGUCHI N.; EMURA S.; HASEGAWA S.; ASAHI H.

    2005-01-01

    @@ Magnetic properties and temperature dependence of electrical transport properties of rare-earth-metal Dy-doped GaN thin film are experimentally studied with a superconducting quantum interference device magnetometer and van der Pauw method. It was found that this thin nitride film has both semiconductor properties and ferromagnetism from 10K to room temperature. The dopant-band (conducting band due to doping) electron conduction dominates the transport properties of this film at low temperatures. These results indicate that Dy-doped GaN is an n-type ferromagnetic semiconductor at room temperature.

  15. Thermodynamic modeling of the RE–Pb (RE = Sc, Dy, Gd) systems

    Energy Technology Data Exchange (ETDEWEB)

    Iddaoudi, A., E-mail: iddaoudi19@gmail.com [Laboratoire de Thermodynamique et Energétique, LTE, Université Ibn-Zohr, B.P. 8106 Agadir (Morocco); Servant, C., E-mail: colette.servant@orange.fr [Laboratoire de Physicochimie de l’Etat Solide, ICMMO, Université Paris-Sud, 91405 Orsay Cedex (France); Selhaoui, N.; Kardellass, S.; Mahdouk, K.; Bouirden, L. [Laboratoire de Thermodynamique et Energétique, LTE, Université Ibn-Zohr, B.P. 8106 Agadir (Morocco)

    2014-03-15

    Highlights: • Rare earth (RE) and Pb alloys or compounds are interesting as magnetic materials. • The phase diagrams and thermodynamic properties of RE–Pb (RE = Sc, Dy, Gd) systems have been assessed. • The CALPHAD method was used with the Redlich–Kister model to optimize the solution phases. • A self-consistent set of thermodynamic parameters has been evaluated. • A good agreement was found between the calculation and experiments. -- Abstract: The phase diagrams and thermodynamic properties of RE–Pb (RE = Sc, Dy, Gd) systems have been assessed by means of the CALPHAD method. The solution phases (liquid, fcc, bcc and hcp) were described by the sublattice formalism and the excess term of the Gibbs energy with the Redlich–Kister equation. The stoichiometric intermetallic compounds (Sc{sub 5}Pb{sub 3}, Sc{sub 6}Pb{sub 5}, Dy{sub 5}Pb{sub 4}, DyPb, DyPb{sub 2}, DyPb{sub 3}, β-Gd{sub 5}Pb{sub 4}, α-Gd{sub 5}Pb{sub 4}, Gd{sub 11}Pb{sub 10}, Gd{sub 6}Pb{sub 7}, GdPb{sub 2} and GdPb{sub 2}) were modeled as line compounds. The non-stoichiometric Dy{sub 5}Pb{sub 3} and Gd{sub 5}Pb{sub 3} phases with a narrow homogeneity range were modeled using a two-sublattice model with substitution. A consistent set of the thermodynamic parameters leading to a reasonable agreement between the calculated results and literature data was obtained.

  16. ISOMER-SELECTED DECAY OF THE GDR IN DY-156

    NARCIS (Netherlands)

    VANSCHAGEN, JPS; HARAKEH, MN; HESSELINK, WHA; NOORMAN, RF

    1995-01-01

    The strength distribution of high-energy gamma-rays emitted in the statistical decay of the 156Dy compound nucleus, with E* = 92.5 MeV, has been measured inclusively and for selected decay pathways in which isomers in 149Dy, 151Dy and 152Dy were populated. For both spectra a deformation \\beta\\ = 0.3

  17. Magnetostrictive distortion in Pr0.15TbxDy0.85-xFe2 polycrystals by X-ray diffraction

    Institute of Scientific and Technical Information of China (English)

    MENG Fan-bin; LI Yang-xian; CHEN Gui-feng; LIU He-yan; QU Jing-ping; CHEN Jing-lan; WU Guang-heng

    2005-01-01

    The ingots of Pr0.15TbxDy0.85-xFe2 (x=0.100.85) series compounds with a single phase were prepared by a arc melting method. The X-ray diffraction patterns were measured using a Philips Xpert MPD X-ray diffractometer with a non-ambient sample stage at different temperatures, the magnetostrictive distortion in Pr0.15TbxDy0.85-xFe2 polycrystals was investigated by X-ray diffraction patterns and the magnetostriction coefficient λ111 was calculated. The results show when the temperature is raised above the spin reorientation temperature region, a splitting appears in the reflection (440); the λ111 increase with the increasing of Tb content for Pr0.15TbxDy0.85-xFe2 polycrystals and the full width at half maximum (FWHM) of the reflection (440) increases gradually with the increasing of Tb content. Moreover, as the FWHM of the reflection (440) decreases gradually with the increasing of temperature, the λ111 decreases slightly with the increasing of temperature at the temperature region of 223373 K for Pr0.15Tb0.3Dy0.55Fe2 alloy.

  18. Observation of room temperature saturated ferroelectric polarization in Dy substituted BiFeO3 ceramics

    KAUST Repository

    Zhang, Shuxia

    2012-04-06

    High quality Bi1− x Dy x FeO3 (0 ≤ x ≤ 0.15) ceramics have been fabricated by sintering Dy-doped BiFeO3 (BFO) precursor powders at a low temperature of 780 °C. The magnetic properties of BFO were improved by the introduction of Dy on the Bi-site. More importantly, well saturated ferroelectric hysteresis loops and polarization switching currents have been observed at room temperature. A large remnant polarization (2P r) value of 62 μC/cm2 is achieved, which is the highest value reported so far for rare-earth-doped BFO ceramics. Moreover, mechanisms for improved multiferroic properties depending on chemical doping-caused structure evolutions have also been discussed.

  19. Structural and photoluminescence properties of Ce, Dy, Er-doped ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Jayachandraiah, C. [Department of Physics, JNTU, Anantapur-515002 (India); Kumar, K. Siva [Department of Advanced Materials Science and Engineering, Dankook University, Cheonan, Chungnam 330-714 (Korea, Republic of); Krishnaiah, G., E-mail: ginnerik@gmail.com [Govt. Degree College, Puttur, Chittoor-517 583 (India)

    2015-06-24

    Undoped ZnO and rare earth elements (Ce, Dy and Er with 2 at. %) doped nanoparticles were synthesized by wet chemical co-precipitation method at 90°C with Polyvinylpyrrolidone (PVP) as capping agent. The structural, morphological, compositional and photoluminescence studies were performed with X-ray diffraction (XRD), Transmission electron microscopy (TEM), Energy dispersive spectroscopy (EDS), FTIR spectroscopy and Photoluminescence (PL) respectively. XRD results revealed hexagonal wurtzite structure with average particle size around 18 nm - 14 nm and are compatible with TEM results. EDS confirm the incorporation of Ce, Dy and Er elements into the host ZnO matrix and is validated by FTIR analysis. PL studies showed a broad intensive emission peak at 558 nm in all the samples. The intensity for Er- doped ZnO found maximum with additional Er shoulder peaks at 516nm and 538 nm. No Ce, Dy emission centers were found in spectra.

  20. TB in Children in the United States

    Science.gov (United States)

    ... in Children Treatment Vaccines Statistics Related Links TB in Children in the United States TB disease in children under ... person with infectious TB disease. Testing for TB in Children In the absence of symptoms, usually the ...

  1. Multidrug-Resistant TB

    Science.gov (United States)

    Cox, Helen; Coomans, Fons

    2016-01-01

    Abstract The right to enjoy the benefits of scientific progress (REBSP) is a little-known but potentially valuable right that can contribute to rights-based approaches to addressing multidrug-resistant TB (MDR-TB). We argue that better understanding of the REBSP may help to advance legal and civil society action for health rights. While the REBSP does not provide an individual entitlement to have a new drug developed for MDR-TB, it sets up entitlements to expect a state to establish a legislative and policy framework aimed at developing scientific capacity to address the most important health issues and at disseminating the outcomes of scientific research. By making scientific findings available and accessible, people can be enabled to claim the use of science for social benefits. Inasmuch as the market fails to address neglected diseases such as MDR-TB, the REBSP provides a potential counterbalance to frame a positive obligation on states to both marshal their own resources and to coordinate the actions of multiple other actors towards this goal, including non-state actors. While the latter do not hold the same level of accountability as states, the REBSP can still enable the recognition of obligations at a level of “soft law” responsibilities.

  2. Properties of Dy 3+-doped PbWO 4 single crystal grown by modified Bridgman method

    Science.gov (United States)

    Huang, Yanlin; Zhu, Wenliang; Feng, Xiqi; Duan, Yong; Man, Zhenyong

    2003-01-01

    Undoped and Dy 3+-doped PbWO 4 single crystals were grown in the same condition by modified Bridgman method. Optical transmittance, X-ray excited luminescence, excitation and emission under UV light, thermoluminescence glow curves and X-ray pulsed excited decays were investigated on Dy 3+:PWO for the first time. Dy 3+-doping has a positive effect similar to that of rare-earth ions La 3+ and Gd 3+, such as improvement of transmittance in the wavelength region of scintillation emission (350-450 nm), compensation of trapping centers that is reflected in the thermoluminescence characteristics and suppression of slow decay component in luminescence kinetics. Analysis of luminescence spectra indicates that energy transfer could take place from the PbWO 4 host to the Dy 3+ ions, followed by characteristic emission line assigned to transition from 4F 9/2 of Dy 3+ ion to lower lying states on basis of the energy level scheme. A tentative concept of energy transfer mechanism is proposed in this paper.

  3. Synthesis of ZnO:Dy Nanopowder and Photoluminescence of Dy3+ in ZnO

    Institute of Scientific and Technical Information of China (English)

    Zhang Linli; Guo Changxin; Zhao Junjing; Hu Juntao

    2005-01-01

    A type of dysprosium-doped ZnO (ZnO:Dy) nanopowder was synthesized by high temperature calcinations. XRD was used to analyze the structure. Photoluminescence spectra were used to study the optical characteristic. PL of ZnO:Dy shows two different spectra which are broad band resulted from the defect of Dy in ZnO and sharp lines from the 4f→4f transition of isolated Dy3+ luminescence center. The emission and excitation spectra depend on the excitation wavelength and the concentration of Dy3+. The broad bands with peaks at 600 and 760 nm are attributed to the recombination from an electron of the defect Dy in ZnO to a hole in VB.

  4. Phase Formation and Magnetic Properties of Nanocomposite Nd-Fe-B Adjusted by Small Amount of Dy and Co

    Institute of Scientific and Technical Information of China (English)

    T S Jang; T W Lim; H S Aum; D H Lee; M B Kim

    2004-01-01

    In order to improve and stabilize the magnetic properties of nanocomposite Nd2Fe14B/α-Fe magnetic alloys by a compositional adjustment, small amount of Dy and/or Co was added to Nd9Fe84B7 alloys. DTA analysis on the amorphous of the alloys took place as the soft magnetic phases were crystallized, and then the hard magnetic Nd2Fe14B was precipitated from them. While α-Fe and a metastable 1:7 (TbCu7-type) phase were formed simultaneously in Dy and Co-free alloys, they were crystallized separately at different temperatures after Dy or Co was added. This phase separation occurred more clearly in the Dy-treated alloys and the other soft magnetic phase Fe3B was also stabilized by Dy and/or Co. The 1: 7 phase that was stabilized by Dy and/or Co was not eliminated at 700 ℃, decreasing magnetic properties of the alloys. It was eventually disappeared above 725 ℃, but Fe3B was not eliminated even at 750 ℃ when Dy was added more than 0.5 at% or Co was added more than 2.0 at%. Amount of Nd2Fe14B in the alloys tended to increase as Dy addition increased,whereas Co addition did not lead to any appreciable change in the ratio of α-Fe and Nd2Fe14B. Moreover, Dy addition apparently increased coercivity of an alloy while Co addition had a beneficial effect on remanence. The grains in the Dytreated alloys were usually finer than those in the Co-treated alloys. The grain size of both α-Fe and Nd2Fe14B in the alloys exhibiting mr ≥ 0.72 was in the range of 20 ~ 40 nm or even larger 50 nm, which is larger than the theoretical optimum size ( ~ 10 nm). Typical magnetic properties obtained from a Nd7.5Dy1.5Fe82.5Co1.5B7 alloy annealed for 12 min at 725 ℃were iHc=4.85 kOe, Br= 11.32 kG, (BH)max = 15.73 MGOe, and mr=0.73.

  5. DySectAPI: Scalable Prescriptive Debugging

    DEFF Research Database (Denmark)

    Jensen, Nicklas Bo; Karlsson, Sven; Quarfot Nielsen, Niklas;

    We present the DySectAPI, a tool that allow users to construct probe trees for automatic, event-driven debugging at scale. The traditional, interactive debugging model, whereby users manually step through and inspect their application, does not scale well even for current supercomputers. While...... lightweight debugging models scale well, they can currently only debug a subset of bug classes. DySectAPI fills the gap between these two approaches with a novel user-guided approach. Using both experimental results and analytical modeling we show how DySectAPI scales and can run with a low overhead...

  6. Magnetic properties and electronic structures of R-Ni-B compounds where R is a heavy rare earth

    Energy Technology Data Exchange (ETDEWEB)

    Burzo, E; Bucur, N; Rednic, V [Faculty of Physics, Babes-Bolyai University, 400084 Cluj-Napoca (Romania); Chioncel, L [Institute of Theoretical Physics, Graz University of Technology, A-8010 Graz (Austria)

    2008-07-09

    Magnetic measurements were performed in the temperature range 4.2-300 K and fields up to 70 kOe on R{sub 3}Ni{sub 7}B{sub 2} compounds with R = Gd, Tb, Dy, Ho, Er. The Curie temperatures decrease from 38.5 K (Gd) to 7 K (Er). Band structure calculations show that nickel, at 0 K, has a very small magnetic polarization, oriented antiparallel to the rare-earth moment. The XPS measurements suggest the presence of unoccupied Ni3d states. The reciprocal susceptibilities follow a Curie-Weiss type behaviour. Effective nickel moments of 1.33 {+-} 0.25 {mu}{sub B} were determined. The magnetic behaviour of nickel is analysed in models which take into account electron correlation effects in d bands.

  7. Magnetic properties and electronic structures of R Ni B compounds where R is a heavy rare earth

    Science.gov (United States)

    Burzo, E.; Bucur, N.; Chioncel, L.; Rednic, V.

    2008-07-01

    Magnetic measurements were performed in the temperature range 4.2-300 K and fields up to 70 kOe on R3Ni7B2 compounds with R = Gd, Tb, Dy, Ho, Er. The Curie temperatures decrease from 38.5 K (Gd) to 7 K (Er). Band structure calculations show that nickel, at 0 K, has a very small magnetic polarization, oriented antiparallel to the rare-earth moment. The XPS measurements suggest the presence of unoccupied Ni3d states. The reciprocal susceptibilities follow a Curie-Weiss type behaviour. Effective nickel moments of 1.33 ± 0.25 µB were determined. The magnetic behaviour of nickel is analysed in models which take into account electron correlation effects in d bands.

  8. Temperature-dependent structure of Tb-doped magnetite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Rice, Katherine P.; Russek, Stephen E., E-mail: stephen.russek@nist.gov; Shaw, Justin M.; Usselman, Robert J.; Evarts, Eric R.; Silva, Thomas J.; Nembach, Hans T. [National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Geiss, Roy H. [Colorado State University, Fort Collins, Colorado 80523 (United States); Arenholz, Elke [Lawrence Berkeley National Laboratory, Advanced Light Source, Berkeley, California 94720 (United States); Idzerda, Yves U. [Department of Physics, Montana State University, Bozeman, Montana 59717 (United States)

    2015-02-09

    High quality 5 nm cubic Tb-doped magnetite nanoparticles have been synthesized by a wet-chemical method to investigate tailoring of magnetic properties for imaging and biomedical applications. We show that the Tb is incorporated into the octahedral 3+ sites. High-angle annular dark-field microscopy shows that the dopant is well-distributed throughout the particle, and x-ray diffraction measurements show a small lattice parameter shift with the inclusion of a rare-earth dopant. Magnetization and x-ray magnetic circular dichroism data indicate that the Tb spins are unpolarized and weakly coupled to the iron spin lattice at room temperature, and begin to polarize and couple to the iron oxide lattice at temperatures below 50 K. Broadband ferromagnetic resonance measurements show no increase in magnetic damping at room temperature for Tb-doped nanoparticles relative to undoped nanoparticles, further confirming weak coupling between Fe and Tb spins at room temperature. The Gilbert damping constant, α, is remarkably low for the Tb-doped nanoparticles, with α = 0.024 ± 0.003. These nanoparticles, which have a large fixed moment, a large fluctuating moment and optically active rare-earth elements, are potential high-relaxivity T1 and T2 MRI agents with integrated optical signatures.

  9. Temperature-dependent structure of Tb-doped magnetite nanoparticles

    Science.gov (United States)

    Rice, Katherine P.; Russek, Stephen E.; Geiss, Roy H.; Shaw, Justin M.; Usselman, Robert J.; Evarts, Eric R.; Silva, Thomas J.; Nembach, Hans T.; Arenholz, Elke; Idzerda, Yves U.

    2015-02-01

    High quality 5 nm cubic Tb-doped magnetite nanoparticles have been synthesized by a wet-chemical method to investigate tailoring of magnetic properties for imaging and biomedical applications. We show that the Tb is incorporated into the octahedral 3+ sites. High-angle annular dark-field microscopy shows that the dopant is well-distributed throughout the particle, and x-ray diffraction measurements show a small lattice parameter shift with the inclusion of a rare-earth dopant. Magnetization and x-ray magnetic circular dichroism data indicate that the Tb spins are unpolarized and weakly coupled to the iron spin lattice at room temperature, and begin to polarize and couple to the iron oxide lattice at temperatures below 50 K. Broadband ferromagnetic resonance measurements show no increase in magnetic damping at room temperature for Tb-doped nanoparticles relative to undoped nanoparticles, further confirming weak coupling between Fe and Tb spins at room temperature. The Gilbert damping constant, α, is remarkably low for the Tb-doped nanoparticles, with α = 0.024 ± 0.003. These nanoparticles, which have a large fixed moment, a large fluctuating moment and optically active rare-earth elements, are potential high-relaxivity T1 and T2 MRI agents with integrated optical signatures.

  10. TB or not TB?: a case of isolated testicular TB with scrotal involvement.

    LENUS (Irish Health Repository)

    Bhargava, A

    2009-06-01

    Despite the genitourinary tract being the most common site affected by extrapulmonary TB, isolated testicular TB remains a rare clinical entity. In patients with co-morbidities such as hepatic impairment, treatment proves a challenge, as first-line hepatotoxic pharmaceuticals are contraindicated. Here, we report a case of isolated testicular TB with scrotal involvement, on a background of hepatic dysfunction.

  11. Spectroscopic studies of interactions involving horseradish peroxidase and Tb3+.

    Science.gov (United States)

    Guo, Shaofen; Zhou, Qing; Lu, Tianhong; Ding, Xiaolan; Huang, Xiaohua

    2008-09-01

    The spectroscopic properties of interactions involving horseradish peroxidase (HRP) and Tb3+ in the simulated physiological solution was investigated with some electrochemical and spectroscopic methods, such as cyclic voltammetry (CV), circular dichroism (CD), X-ray photoelectron spectroscopy (XPS) and synchronous fluorescence (SF). It was found that Tb3+ can coordinate with oxygen atoms in carbonyl groups in the peptide chain of HRP, form the complex of Tb3+ and HRP (Tb-HRP), and then lead to the conformation change of HRP. The increase in the random coil content of HRP can disturb the microstructure of the heme active center of HRP, in which the planarity of the porphyrin cycle in the heme group is increased and then the exposure extent of the electrochemical active center is decreased. Thus Tb3+ can inhibit the electrochemical reaction of HRP and its electrocatalytic activity for the reduction of H2O2 at the Au/Cys/GC electrode. The changes in the microstructure of HRP obstructed the electron transfer of Fe(III) in the porphyrin cycle of the heme group, thus HRP catalytic activity is inhibited. The inhibition effect of Tb3+ on HRP catalytic activity is increased with the increasing of Tb3+ concentration. This study would provide some references for better understanding the rare earth elements and heavy metals on peroxidase toxicity in living organisms.

  12. Novel organic–inorganic amorphous photoactive hybrid films with rare earth (Eu{sup 3+}, Tb{sup 3+}) covalently embedded into silicon–oxygen network via sol–gel process

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qiang; Sheng, Ye; Zheng, Keyan; Qin, Xuming; Ma, Pingchuan; Zou, Haifeng, E-mail: haifengzou0431@gmail.com

    2015-10-15

    Highlights: • The hybrids are prepared through the hydrolysis and condensation process. • The hybrids are amorphous and heat stabilized. • The hybrids containing Eu{sup 3+} and Tb{sup 3+} show the typical red and green emissions. - Abstract: Novel organic–inorganic hybrid amorphous thin films were synthesized by linking lanthanide (Tb{sup 3+}, Eu{sup 3+}) complexes through 3,4-bis(3-(triethoxysilyl)propylcarbamoyloxy)benzoic acid using sol–gel method. These inorganic–organic hybrids were characterized in detail by Fourier transform infrared spectroscopy, wide angle X-ray diffraction, themogravimetric analysis, scanning electron microscope, and fluorescence spectra. The above research results indicate that the hybrids possess high thermal-stability, amorphous structure features and especially favorable luminescent performances, such as long luminescent decay lifetime, high quantum yield etc.

  13. Peculiarity of component interaction in {l_brace}Y, Dy{r_brace}-Mn-Sn ternary systems

    Energy Technology Data Exchange (ETDEWEB)

    Romaka, V.V. [Department of Materials Engineering and Applied Physics, Lviv Polytechnic National University, Ustyyanovycha Str. 5, 79013 Lviv (Ukraine); Konyk, M. [Inorganic Chemistry Department, Ivan Franko Lviv National University, Kyryla and Mefodiya Str. 6, 79005 Lviv (Ukraine); Romaka, L., E-mail: romakal@franko.lviv.ua [Inorganic Chemistry Department, Ivan Franko Lviv National University, Kyryla and Mefodiya Str. 6, 79005 Lviv (Ukraine); Pavlyuk, V. [Inorganic Chemistry Department, Ivan Franko Lviv National University, Kyryla and Mefodiya Str. 6, 79005 Lviv (Ukraine); Jan Dlugosz University, Institute of Chemistry, Environmental Protection and Biotechnology, al. Armii Krajowej 13/15, 42200 Czestochowa (Poland); Ehrenberg, H. [Institute for Complex Materials, IFW Dresden, Helmholtzstrasse 20, D-01069 Dresden (Germany); Tkachuk, A. [Inorganic Chemistry Department, Ivan Franko Lviv National University, Kyryla and Mefodiya Str. 6, 79005 Lviv (Ukraine)

    2011-07-14

    Highlights: > {l_brace}Y, Dy{r_brace}-Mn-Sn ternary systems at 770 K are characterized by formation of stannides with general compositions RMn{sub 6}Sn{sub 6} and R{sub 4}Mn{sub 4}Sn{sub 7}. > The crystal structure of YMn{sub 6}Sn{sub 6} was determined by single crystal and powder diffraction methods. > Structural analysis showed that Dy{sub 4}Mn{sub 4}Sn{sub 7} compound is disordered. > Isostructural R{sub 4}Mn{sub 4}Sn{sub 7} compounds were also found with Gd, Tb, Ho, Er, Tm(confirmed), Yb, and Lu. - Abstract: The phase equilibria in the Y-Mn-Sn and Dy-Mn-Sn ternary systems were studied at 770 K by means of X-ray and metallographic analyses in the whole concentration range. Both Y-Mn-Sn and Dy-Mn-Sn systems are characterized by formation of two ternary compounds RMn{sub 6}Sn{sub 6} (MgFe{sub 6}Ge{sub 6}-type, space group P6/mmm) and R{sub 4}Mn{sub 4}Sn{sub 7} (Zr{sub 4}Co{sub 4}Ge{sub 7}-type, space group I4/mmm). The disorder in Dy{sub 4}Mn{sub 4}Sn{sub 7} compound was found by single crystal method. Compounds with the same type of structure were also found with Gd, Tb, Ho, Er, Tm (confirmed), Yb, and Lu and their lattice parameters were determined.

  14. Magnetic alignment study of rare-earth-containing liquid crystals.

    Science.gov (United States)

    Galyametdinov, Yury G; Haase, Wolfgang; Goderis, Bart; Moors, Dries; Driesen, Kris; Van Deun, Rik; Binnemans, Koen

    2007-12-20

    The liquid-crystalline rare-earth complexes of the type [Ln(LH)3(DOS)3]-where Ln is Tb, Dy, Ho, Er, Tm, or Yb; LH is the Schiff base N-octadecyl-4-tetradecyloxysalicylaldimine; and DOS is dodecylsulfate-exhibit a smectic A phase. Because of the presence of rare-earth ions with a large magnetic anisotropy, the smectic A phase of these liquid crystals can be easier aligned in an external magnetic field than smectic A phases of conventional liquid crystals. The magnetic anisotropy of the [Ln(LH)3(DOS)3] complexes was determined by measurement of the temperature-dependence of the magnetic susceptibility using a Faraday balance. The highest value for the magnetic anisotropy was found for the dysprosium(III) complex. The magnetic alignment of these liquid crystals was studied by time-resolved synchrotron small-angle X-ray scattering experiments. Depending on the sign of the magnetic anisotropy, the director of the liquid-crystalline molecules was aligned parallel or perpendicular to the magnetic field lines. A positive value of the magnetic anisotropy (and parallel alignment) was found for the thulium(III) and the ytterbium(III) complexes, whereas a negative value of the magnetic anisotropy (and perpendicular alignment) was observed for the terbium(III) and dysprosium(III) complexes.

  15. Mid-infrared emission from Dy3+ doped tellurite bulk glass and waveguides

    Science.gov (United States)

    Richards, Billy D. O.; Teddy-Fernandez, Toney; Jha, Animesh; Binks, David

    2012-11-01

    We present the fabrication and characterisation of Dy3+-doped tellurite glasses and waveguides for applications in the mid-IR. The low phonon energy and large rare-earth ion solubility of tellurite glasses, as well as having infrared transmission ranges up to glasses, glass characterisation and rare-earth ion spectroscopy which is compared to other glass hosts relevant to the mid-IR such as fluoride glasses. When excited with an 808 nm laser diode source, Dy3+ doped tellurite bulk glasses exhibited very broad fluorescence from the 6H13/2 - 6H15/2 transition which extends from 3 μm to 3.6 μm FWHM compared to 2.9 μm to 3.1 μm in Dy3+ doped ZBLAN glass. This broad and red-shifted fluorescence band in tellurite glass may find use in LIDAR and sensing applications as it coincides with an atmospheric transmission band, compared to the ~3 μm emission of Dy3+ doped ZBLAN lasers which is absorbed by atmospheric water.

  16. Effect of Y2O3 and Dy2O3 on Microstructure and Mechanical Behaviors of Aluminum Nitride Ceramics

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The effects of two types of additives, Y2O3 and Dy2O3, on the sintering and mechanical behaviors of AlN ceramics were investigated. The experimental results show that the sintering temperature can be decreased and the mechanical behavior can be improved by adding rare earth in AlN ceramics. The strength of AlN ceramics with Y2O3 and Dy2O3 are 326 and 320 MPa, respectively, which are 97.6% and 93.9% higher than the un-doped AlN ceramics. The fracture behavior on the fracture surfaces of rare earth oxide AlN ceramics was found to be a mixed mode of transgranular fracture and intergranular fracture. As a result, it is concluded that the improvement of bending strength of AlN ceramics with Y2O3 and Dy2O3 addition are mainly achieved by strengthening the grain boundary.

  17. Reversing ferroelectric polarization in multiferroic DyMn2O5 by nonmagnetic Al substitution of Mn

    Science.gov (United States)

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

    2014-08-01

    The multiferroic RMn2O5 family, where R is rare-earth ion or Y, exhibits rich physics of multiferroicity which has not yet well understood. DyMn2O5 is a representative member of this family. The ferroelectric polarization of DyMn2O5 is claimed to be magnetically relevant and have more than one component. Therefore, the polarization reversal upon the sequent magnetic transitions is expected. We investigate the evolution of the ferroelectric polarization upon a partial substitution of Mn3+ by nonmagnetic Al3+ in order to tailor the Mn3+-Mn4+ interactions and then to modulate the polarization in DyMn2-x/2Alx/2O5. It is revealed that the polarization can be successfully reversed by Al-substitution via substantially suppressing the Mn3+-Mn4+ interactions, while the Dy3+-Mn4+ interactions can sustain against the substitution until a level as high as x = 0.2. In addition, the independent Dy spin ordering is shifted remarkably down to an extremely low temperature due to the Al3+ substitution. The present work unveils the possibility of tailoring the Mn3+-Mn4+ and Dy3+-Mn4+ interactions independently, and thus reversing the ferroelectric polarization.

  18. X-ray magnetic circular dichroism study of Dy-doped Bi2Te3 topological insulator thin films

    Science.gov (United States)

    Figueroa, A. I.; Baker, A. A.; Harrison, S. E.; Kummer, K.; van der Laan, G.; Hesjedal, T.

    2017-01-01

    Magnetic doping of topological insulators (TIs) is crucial for unlocking novel quantum phenomena, paving the way for spintronics applications. Recently, we have shown that doping with rare earth ions introduces large magnetic moments and allows for high doping concentrations without the loss of crystal quality, however no long range magnetic order was observed. In Dy-doped Bi2Te3 we found a band gap opening above a critical doping concentration, despite the paramagnetic bulk behavior. Here, we present a surface-sensitive x-ray magnetic circular dichroism (XMCD) study of an in situ cleaved film in the cleanest possible environment. The Dy M4,5 absorption spectra measured with circularly polarized x-rays are fitted using multiplet calculations to obtain the effective magnetic moment. Arrott-Noakes plots, measured by the Dy M5 XMCD as a function of field at low temperatures, give a negative transition temperature. The evaporation of a ferromagnetic Co thin film did not introduce ferromagnetic ordering of the Dy dopants either; instead a lowering of the transition temperature was observed, pointing towards an antiferromagnetic ordering scenario. This result shows that there is a competition between the magnetic exchange interaction and the Zeeman interaction. The latter favors the Co and Dy magnetic moments to be both aligned along the direction of the applied magnetic field, while the exchange interaction is minimized if the Dy and Co atoms are antiferromagnetically coupled, as in zero applied field.

  19. Electron spin resonance evaluation of pure CaSO4 and as a phosphor doped with P and Dy.

    Science.gov (United States)

    de Jesus, E F O; Rossi, A M; Lopes, R T

    2002-01-01

    Polycrystalline CaSO4 powder, doped with different elements but mainly rare earths, is one of the most interesting thermoluminescent (TL) materials. Although many electron spin resonance (ESR) analyses have been reported for these materials few studies have been published about the potential of CaSO4 for ESR dosimetry; almost all studies used CaSO4:Dy with a very low Dy concentration as the material for TL measurements. Pure CaSO4 from Merck was used to prepare CaSO4:Dy and CaSO4:P:Dy with different Dy concentrations. Samples were annealed at 600 degrees C for 1 h before irradiation in a Gammacell 220 irradiator with a 60Co gamma source at a dose rate of 100 Gy x min(-1). The ESR spectra of the pure CaSO4 and CaSO4 doped with P and Dy show the lines usually observed with these types of material, with the factor g around 2.036 and an intense line at g = 2.0011 found only in the pure material. This line, probably an axial SO4-, grows linearly with absorbed dose until 1.0 kGy and shows good stability with time. The line should be stabilized by matrix impurities because it can be removed by a simple treatment with hot sulphuric acid.

  20. Chemical Bond Parameters in Sr3MRhO6 (M=Rare earth)

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Chemical bond parameters, that is, bond covalency, bond valence, macroscopic linear susceptibility, and oxidation states of elements in Sr3MRhO6 (M=Sm, Eu, Tb, Dy, Ho, Er, Yb) have been calculated. The results indicate that the bond covalency of M-O decreases sharply with the decrease of ionic radius of M3+ from Sm to Yb, while no obvious trend has been found for Rh-O and Sr-O bonds. The global instability index indicates that the crystal structures of Sr3MrhO6 (M = Sm, Eu, Tb, Dy, Ho) have strained bonds.

  1. Dy{sup 3+}:Ca{sub 2}SnO{sub 4}, a new yellow phosphor with afterglow behavior

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Mingming; Zhang, Dongyun, E-mail: dyz@sit.edu.cn; Chang, Chengkang

    2015-08-05

    Highlights: • The photoluminescence and afterglow behavior of Dy{sup 3+}:Ca{sub 2}SnO{sub 4} was investigated. • PL spectra revealed the {sup 4}F{sub 9/2} → {sup 6}H{sub J} (J = 15/2, 13/2, 11/2) energy transition of Dy{sup 3+} ions in Ca{sub 2}SnO{sub 4}. • CIE chromaticity coordinates results confirmed a yellow light emitting of the Dy{sup 3+}:Ca{sub 2}SnO{sub 4}. • After the UV source was turned off, the Dy{sup 3+}:Ca{sub 2}SnO{sub 4} showed typical afterglow behavior. • The afterglow behavior of Dy{sup 3+}:Ca{sub 2}SnO{sub 4} was attributed to suitable electron and hole traps. - Abstract: This paper reports the photoluminescence and afterglow behavior of Dy{sup 3+} in Ca{sub 2}SnO{sub 4} matrix (Dy{sup 3+}:Ca{sub 2}SnO{sub 4}) prepared via a solid-state reaction. X-ray diffraction (XRD), photo luminescence spectroscope (PLS) and thermal luminescence spectroscope (TLS) were performed to investigate the physical properties of the phosphors. Typical {sup 4}F{sub 9/2} to {sup 6}H{sub j} energy transition of Dy{sup 3+} ions was detected by PL spectra. CIE chromaticity coordinates of x = 0.4319, y = 4.456, calculated from the emission spectra, confirmed a yellow light emitting of the Dy{sup 3+}:Ca{sub 2}SnO{sub 4} phosphors. The Ca{sub 2}SnO{sub 4} phosphors showed a typical afterglow behavior when the UV source was switched off. Thermal simulated luminescence study indicated that the persistent afterglow of Dy{sup 3+}:Ca{sub 2}SnO{sub 4} phosphors was generated by the suitable electron or hole traps which was resulted from the doping the Ca{sub 2}SnO{sub 4} host with rare-earth ions (Dy{sup 3+})

  2. Extensively Drug-Resistant Tuberculosis (XDR TB)

    Science.gov (United States)

    ... the Facts Tuberculosis - The Connection between TB and HIV 12-Dose Regimen for Latent TB Infection-Patient Education Brochure Posters Mantoux Tuberculin Skin Test Wall Chart World TB Day Think TB Stop TB Reports & Articles Morbidity and Mortality Weekly Reports (MMWRs) DTBE Authored ...

  3. Preparation, thermodynamic property and antimicrobial activity of some rare-earth (III) complexes with 3-bromo-5-iodobenzoic acid and 1,10-phenanthroline

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jing-Yu [Testing and Analysis Center, Hebei Normal University, Shijiazhuang 050024 (China); College of Chemistry and Material Science, Hebei Normal University, Shijiazhuang 050024 (China); Ren, Ning [Department of Chemistry, Handan College, Handan 056005 (China); Zhang, Jian-Jun, E-mail: jjzhang6@126.com [Testing and Analysis Center, Hebei Normal University, Shijiazhuang 050024 (China); College of Chemistry and Material Science, Hebei Normal University, Shijiazhuang 050024 (China); Zhang, Cun-Ying [No.1 High School of Shijiazhuang, Shijiazhuang 050011 (China)

    2013-10-20

    Graphical abstract: Four new rare-earth complexes of general formula [Ln(3-Br-5-IBA){sub 3}phen]{sub 2} [Ln = Er (1), Tb (2), Dy (3) and Ho (4); 3-Br-5-IBA = 3-bromo-5-iodobenzoate; phen = 1,10-phenanthroline] were synthesized and characterized by elemental analysis, IR, UV and TG/DSC-FTIR technology. Heat capacities of the four complexes were measured by differential scanning calorimetry (DSC). The antimicrobial activity against Escherichia coli, Staphylococcus aureus and Candida albicans were tested using disc diffusion method. - Highlights: • Four new complexes [Ln(3-Br-5-IBA){sub 3}phen]{sub 2} were synthesized and characterized. • The non-isothermal kinetics of the first stage for the complexes was studied. • The heat capacities of the complexes were measured by differential scanning calorimeter. • The antimicrobial activities for these complexes were tested. • The fluorescence properties of the complexes 2 and 3 were studied. - Abstract: Four new rare-earth complexes of general formula [Ln(3-Br-5-IBA){sub 3}phen]{sub 2} (Ln(III) = Er (1), Tb (2), Dy (3) and Ho (4); 3-Br-5-IBA = 3-bromo-5-iodobenzoate; phen = 1,10-phenanthroline) were synthesized by solution-precipitation method, and investigated using elemental analysis, infrared spectra, ultraviolet spectra and TG/DSC-FTIR technology. The non-isothermal kinetics of the first stage for the complexes was studied by using non-linear integral isoconversional method and double equal-double steps method. The heat capacities of the complexes were measured between 263.15 and 485.55 K by means of differential scanning calorimeter, and the values of the experimental heat capacities were fitted to a polynomial equation with the least-squares method. And the thermodynamic functions [H{sub T} − H{sub 298.15}], [S{sub T} − S{sub 298.15}] and [G{sub T} − G{sub 298.15}] were also derived based on the fitted polynomials and thermodynamic relationships with temperature interval of 10 K. Moreover, the

  4. Optical down-conversion in doped ZnSe:Tb3+ nanocrystals.

    Science.gov (United States)

    Das, Sandip; Mandal, Krishna C

    2013-02-07

    Rare earth (RE) Tb(3+)-doped high quality ZnSe nanocrystals (NCs) were synthesized by a facile chemical hot-injection method. ZnSe:Tb(3+) nanocrystals exhibited broadband absorption below the first excitonic absorption peak. Photoluminescence spectra showed Tb(3+) emission lines in the visible spectral window at room temperature when excited by UV radiation below the band-edge of the host ZnSe nanocrystals. Our experimental results indicate optical down-conversion in these Tb(3+)-doped Zn-chalcogenide nanocrystals via energy migration from host ZnSe to the Tb(3+) dopant. The host-dopant energy transfer mechanism for this ZnSe:Tb(3+) nanocrystal system is correlated with the emission spectra.

  5. Stability of Rare Earth Ion-N,N′-bis(2′-Pyridine)methyl-1,10-Phenanthroline-2,9-Dimethanmine Binary Complexes

    Institute of Scientific and Technical Information of China (English)

    刘天府; 王中明; 林华宽; 朱守荣; 徐猛; 陈云悌

    2003-01-01

    The stability constants of binary complexes Ln-L (Ln=La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, L=N, N′-bis(2′-pyridine)methyl-1,10-phenanthroline-2,9- dimethanamine) were determined by pH potentiometric titration method at 25±0.1 ℃ in 0.1 mol*L-1 NaClO4. The probable structures of the corresponding complexes were proposed. The influence of the metal ions to the stability of binary complexes and the stability difference between the complexes of rare earth ion and the corresponding complexes of Co2+, Ni2+, Cu2+ ions were discussed. The stability constants of the corresponding binary complex of radioactive Pm3+ ion were estimated by linear regression.

  6. Simultaneous determination of rare earth elements in ore and anti-corrosion coating samples using a portable capillary electrophoresis instrument with contactless conductivity detection.

    Science.gov (United States)

    Nguyen, Thi Anh Huong; Nguyen, Van Ri; Le, Duc Dung; Nguyen, Thi Thanh Binh; Cao, Van Hoang; Nguyen, Thi Kim Dung; Sáiz, Jorge; Hauser, Peter C; Mai, Thanh Duc

    2016-07-29

    The employment of an in-house-made capillary electrophoresis (CE) instrument with capacitively coupled contactless conductivity detection (C(4)D) as a simple and inexpensive solution for simultaneous determination of many rare earth elements (REEs) in ore samples from Vietnam, as well as in anti-corrosion coating samples is reported. 14 REEs (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) were determined using an electrolyte composed of 20mM arginine and 10mM α-hydroxyisobutyric acid adjusted to pH 4.2 with acetic acid. The best detection limit achieved was 0.24mg/L using the developed CE-C(4)D method. Good agreement between results from CE-C(4)D and the confirmation method (ICP-MS) was achieved, with a coefficient of determination (r(2)) for the two pairs of data of 0.998.

  7. Calculation of the magnetic properties of pseudo-ternary R2M14B intermetallic compounds (R = rare earth, M = Fe, Co

    Directory of Open Access Journals (Sweden)

    Gabriel Gómez Eslava

    2016-06-01

    Full Text Available The extrinsic properties of NdFeB-based magnets can be tuned through partial substitution of Nd by another rare-earth element and Fe by Co, as such substitution leads to a modification in the intrinsic properties of the main phase. Optimisation of a magnet's composition through trial and error is time consuming and not straightforward, since the interplay existing between magnetocrystalline anisotropy and coercivity is not completely understood. In this paper we present a model to calculate the intrinsic magnetic properties of pseudo-ternary Nd2Fe14B-based compounds. As concrete examples, which are relevant for the optimisation of NdFeB-based high-performance magnets used in (hybrid electric vehicles and wind turbines, we consider partial substitution of Nd by Dy or Tb, and Fe by Co.

  8. 94 {beta}-Decay Half-Lives of Neutron-Rich 55Cs to 67Ho: Experimental Feedback and Evaluation of the r-Process Rare-Earth Peak Formation

    Energy Technology Data Exchange (ETDEWEB)

    Wu, J.; Nishimura, S.; Lorusso, G.; Moller, P; Ideguchi, E; Regan, P. H.; Simpson, G. S.; Soderstrom, P. -A.; Walker, P. M.; Watanabe, H.; Kondev, F. G.

    2017-02-17

    The β-decay half-lives of 94 neutron-rich nuclei 144$-$151Cs, 146$-$154Ba, 148$-$156La, 150$-$158Ce, 153$-$160Pr, 156$-$162Nd, 159$-$163Pm, 160$-$166Sm, 161$-$168Eu, 165$-$170Gd, 166$-$172Tb, 169$-$173Dy, 172$-$175Ho, and two isomeric states 174mEr, 172mDy were measured at the Radioactive Isotope Beam Factory, providing a new experimental basis to test theoretical models. Strikingly large drops of β-decay half-lives are observed at neutron-number N = 97 for 58Ce, 59Pr, 60Nd, and 62Sm, and N = 105 for 63Eu, 64Gd, 65Tb, and 66Dy. Lastly, features in the data mirror the interplay between pairing effects and microscopic structure. r-process network calculations performed for a range of mass models and astrophysical conditions show that the 57 half-lives measured for the first time play an important role in shaping the abundance pattern of rare-earth elements in the solar system

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Z. Y.; Wang, Y. L.; Lin, L.; Liu, M. F.; Li, X.; Yan, Z. B.; Liu, J.-M. [Laboratory of Solid State Microstructures and Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)

    2015-11-07

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

  10. Multiple magnetic relaxation processes, magnetocaloric effect and fluorescence properties of rhombus-shaped tetranuclear rare earth complexes.

    Science.gov (United States)

    Gao, Hong-Ling; Jiang, Li; Liu, Shuang; Shen, Hai-Yun; Wang, Wen-Min; Cui, Jian-Zhong

    2016-01-07

    Seven new tetranuclear rare earth (RE) complexes [RE4(acac)4L6(μ3-OH)2] (HL = 5-(4-fluorobenzylidene)-8-hydroxylquinoline; acac = acetylacetonate; RE = Y (1), Eu (2), Gd (3), Tb (4), Dy (5), Tm (6) and Lu (7)) have been synthesized and completely characterized. Complex exhibits multiple zero-field slow magnetic relaxation processes typical of Single Molecule Magnets (SMMs). Two distinct slow magnetic relaxation processes, with effective energy barriers of Ueff = 48 K for the slow relaxation (SR) process and Ueff = 121 K for the fast relaxation (FR) process, are mainly attributed to the presence of two crystallographically independent Dy(III) sites. The magnetocaloric effect (MCE) was detected as -ΔSm(T) = 20.8 J kg(-1) K(-1) for complex . The fluorescence properties of complexes 1, 2, 4, 5 and 7 were also investigated. Complexes 2, 4 and 5 show the characteristic peaks for their corresponding RE(III) center, while complexes 1 and 7 show similar emission peaks to the Schiff base ligand when they are excited at the appropriate wavelength.

  11. Exploring the biocatalytic potential of a DyP-type peroxidase by profiling the substrate acceptance of Thermobifida fusca DyP peroxidase

    NARCIS (Netherlands)

    Loncar, Nikola; Colpa, Dana I.; Fraaije, Marco W.

    2016-01-01

    Dye-decolorizing peroxidases (DyPs) represent a new class of oxidative enzymes for which the natural substrates are largely unknown. To explore the biocatalytic potential of a DyP, we have studied the substrate acceptance profile of a robust DyP peroxidase, a DyP from Thermobifida fusca (TfuDyP). Wh

  12. Preparation, structural and magnetic characterization of DyCrMnO 5

    Science.gov (United States)

    Martínez-Lope, M. J.; Retuerto, M.; García-Hernández, M.; Alonso, J. A.

    2009-03-01

    The title compound has been first synthesized by a citrate technique followed by thermal treatments under moderate oxygen pressure conditions, and characterized by X-ray and neutron powder diffraction (NPD) and magnetization measurements. The crystal structure of DyCrMnO 5 has been refined from NPD data in the space group Pbam; a=7.2617(6) Å, b=8.5161(6) Å, and c=5.7126(5) Å at 295 K. This oxide is isostructural with RMn 2O 5 oxides ( R=rare earths) and it contains infinite chains of (Cr, Mn) 4+O 6 octahedra-sharing edges, linked together by (Mn, Cr) 3+O 5 pyramids and DyO 8 units. The high degree of antisite disordering exhibited by DyCrMnO 5 is noteworthy. The octahedral positions are occupied by roughly 50% of Mn and Cr cations, and the pyramidal groups contain two thirds of Mn and one third of Cr cations. We assume that Mn and Cr cations at the octahedral positions exhibit a tetravalent oxidation state, whereas the metals at the pyramidal positions are trivalent, in order to preserve the electroneutrality of this oxide. The susceptibility vs temperature curve of DyCrMnO 5 does not suggest the establishment of a long-range magnetic structure even at low temperatures; the NPD technique does not provide any signal of magnetic ordering, since the reflections do not show any magnetic contribution.

  13. Thermal, optical and structural properties of Dy3+ doped sodium aluminophosphate glasses

    Science.gov (United States)

    Kaur, Manpreet; Singh, Anupinder; Thakur, Vanita; Singh, Lakhwant

    2016-03-01

    Trivalent Dysprosium doped sodium aluminophosphate glasses with composition 50P2O5-10Al2O3-(20-x)Na2O-20CaO-xDy2O3 (x varying from 0 to 5 mol%) were prepared by melt quench technique. The density of the prepared samples was measured using Archimedes principle and various physical properties like molar volume, rare earth ion concentration, polaron radius, inter nuclear distance and field strength were calculated using different formulae. The differential scanning calorimetry (DSC) was carried out to study the thermal stability of prepared glasses. The UV Visible absorption spectra of the dysprosium doped glasses were found to be comprised of ten absorption bands which correspond to transitions from ground state 6H15/2 to various excited states. The indirect optical band gap energy of the samples was calculated by Tauc's plot and the optical energy was found to be attenuated with Dy3+ ions. The photoluminescence spectrum revealed that Dy3+ doped aluminophosphate glasses have strong emission bands in the visible region. A blue emission band centred at 486 nm, a bright yellow band centred at 575 nm and a weak red band centred at 668 nm were observed in the emission spectrum due to excitation at 352 nm wavelength. Both FTIR and Raman spectra assert slight structural changes induced in the host glass network with Dy3+ ions.

  14. The interplay of long-range magnetic order and single-ion anisotropy in rare earth nickel germanides

    Energy Technology Data Exchange (ETDEWEB)

    Islam, Z.

    1999-05-10

    This dissertation is concerned with the interplay of long-range order and anisotropy in the tetragonal RNi{sub 2}Ge{sub 2} (R = rare earth) family of compounds. Microscopic magnetic structures were studied using both neutron and x-ray resonant exchange scattering (XRES) techniques. The magnetic structures of Tb, Dy, Eu and Gd members have been determined using high-quality single-crystal samples. This work has correlated a strong Fermi surface nesting to the magnetic ordering in the RNi{sub 2}Ge{sub 2} compounds. Generalized susceptibility, {chi}{sub 0}(q), calculations found nesting to be responsible for both incommensurate ordering wave vector in GdNi{sub 2}Ge{sub 2}, and the commensurate structure in EuNi{sub 2}Ge{sub 2}. A continuous transition from incommensurate to commensurate magnetic structures via band filling is predicted. The surprisingly higher T{sub N} in EuNi{sub 2}Ge{sub 2} than that in GdNi{sub 2}Ge{sub 2} is also explained. Next, all the metamagnetic phases in TbNi{sub 2}Ge{sub 2} with an applied field along the c axis have been characterized with neutron diffraction measurements. A mixed phase model for the first metamagnetic structure consisting of fully-saturated as well as reduced-moment Tb ions is presented. The moment reduction may be due to moment instability which is possible if the exchange is comparable to the low-lying CEF level splitting and the ground state is a singlet. In such a case, certain Tb sites may experience a local field below the critical value needed to reach saturation.

  15. Strategic design and refinement of Lewis acid-base catalysis by rare-earth-metal-containing polyoxometalates.

    Science.gov (United States)

    Suzuki, Kosuke; Sugawa, Midori; Kikukawa, Yuji; Kamata, Keigo; Yamaguchi, Kazuya; Mizuno, Noritaka

    2012-06-18

    Efficient polyoxometalate (POM)-based Lewis acid-base catalysts of the rare-earth-metal-containing POMs (TBA(6)RE-POM, RE = Y(3+), Nd(3+), Eu(3+), Gd(3+), Tb(3+), or Dy(3+)) were designed and synthesized by reactions of TBA(4)H(4)[γ-SiW(10)O(36)] (TBA = tetra-n-butylammonium) with RE(acac)(3) (acac = acetylacetonato). TBA(6)RE-POM consisted of two silicotungstate units pillared by two rare-earth-metal cations. Nucleophilic oxygen-enriched surfaces of negatively charged POMs and the incorporated rare-earth-metal cations could work as Lewis bases and Lewis acids, respectively. Consequently, cyanosilylation of carbonyl compounds with trimethylsilyl cyanide ((TMS)CN) was efficiently promoted in the presence of the rare-earth-metal-containing POMs via the simultaneous activation of coupling partners on the same POM molecules. POMs with larger metal cations showed higher catalytic activities for cyanosilylation because of the higher activation ability of C═O bonds (higher Lewis acidities) and sterically less hindered Lewis acid sites. Among the POM catalysts examined, the neodymium-containing POM showed remarkable catalytic performance for cyanosilylation of various kinds of structurally diverse ketones and aldehydes, giving the corresponding cyanohydrin trimethylsilyl ethers in high yields (13 substrates, 94-99%). In particular, the turnover frequency (714,000 h(-1)) and the turnover number (23,800) for the cyanosilylation of n-hexanal were of the highest level among those of previously reported catalysts.

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

    Energy Technology Data Exchange (ETDEWEB)

    Nisius, D.; Janssens, R.V.F.; Crowell, B. [and others

    1995-08-01

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

  17. TB control: challenges and opportunities for India.

    Science.gov (United States)

    Pai, Madhukar; Daftary, Amrita; Satyanarayana, Srinath

    2016-03-01

    India's TB control programme has treated over 19 million patients, but the incidence of TB continues to be high. TB is a major killer and drug-resistant TB is a growing threat. There are several likely reasons, including social conditions and co-morbidities that fuel the TB epidemic: under-investment by the government, weak programme implementation and management, suboptimal quality of care in the private sector, and insufficient advocacy around TB. Fortunately, India possesses the technical know-how, competence and resources to address these challenges. The End TB Strategy by WHO offers India an excellent blueprint to advance the agenda of TB control.

  18. Dy3+掺杂硼酸盐玻璃的制备、表征及发光特性%Preparation,Characterization and Luminescence Properties of Dy3+ Doped Borate Glasses

    Institute of Scientific and Technical Information of China (English)

    乔荫颇; 张攀; 殷海荣; 李艳肖; 刘晶; 周沁

    2016-01-01

    A series of Dy3+ doped B2 O3-ZnO-Na2 O-Al2 O3 glasses ( BZNA:xDy) were prepared by high temperature melting method. The structure,composition and luminescence property of BZNA:xDy samples were characterized through FTIR, UV-Vis-NIR and fluorescence spectra. The absorp-tion spectra showed the characteristics peaks of glass substrate and the energy level transition of Dy3+. Under 350 nm excitation, the luminescence intensity, ratio of yellow and blue emission peaks, fluorescence lifetime, color coordinate and color temperature of BZNA:xDy samples can be adjusted and changed according to the content of Dy3+. The luminescent intensity of Dy3+ doped samples are observed to be enhanced firstly and then decrease after 1. 0% of Dy3+ mole fraction. Thus, the concentration quenching of Dy occurs in the samples. Meanwhile, the fluorescence life-time of samples decreases with the increasing doping concentration of rare earth ions. Furthermore, the chromaticity coordinates values and the color temperatures of the emission are reduced gradually.%采用高温熔融-冷却法制备了一系列Dy3+掺杂的B2 O3-ZnO-Na2 O-Al2 O3发光玻璃,通过红外光谱、紫外-可见-近红外光谱和荧光光谱等研究了其结构及发光特性。分析表明:制备的发光玻璃中出现基质组分的结构特征峰及Dy3+的能级跃迁特征峰。在350 nm波长光激发下,样品的发光强度、黄蓝发射峰比、荧光寿命、色坐标及色温等均随Dy3+浓度的变化发生明显的可调节变化。样品的荧光发射强度随Dy3+浓度的增加呈现先增大后减小的变化,当Dy3+掺杂摩尔分数为1.0%时,发光强度最大。此外,随着Dy3+掺杂浓度的增大,发光玻璃的荧光寿命及发射光谱的色度坐标值、色温都呈现递减的趋势。这表明通过基质组分及掺杂元素的调节可以使得该硼酸盐体系发光玻璃获得高效可调节的光功能从而得到广泛应用。

  19. Dy3Al5O12磁热性质研究∗%Study on the magnetic and magneto caloric effects of Dy3Al5O12

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    The crystal field (CF)- and external magnetic field- split ground state of Dy3+ in Dy3Al5O12 (DyAG) has been calculated based on the quantum theory in this paper. The eight CF-split levels are obtained, which are all twofold degenerates and are removed by the external magnetic field. On the basis of the results, the magnetic moments and the magnetic entropy changes of DyAG are calculated in the temperature range of 3 < T < 42 K and the magnetic field range of 0DyAG have contribution to the average magnetic moment and have an important impact on the magnetic anisotropy of the crystal. In addition, the study indicates that the exchange interaction between the magnetic ions in DyAG is so weak that it may be neglected. However, distinct from DyAG, the exchange interaction between the rare-earth ions in Gd3Ga5O12(GdGG) is stronger at low temperatures and dependent on the temperature and external magnetic field. Besides, the variation of the adiabatic temperature change ∆T with T is theoretically anticipated and the anticipated results are comparied with that of GdGG. It is found that the maximum adiabatic temperature change ∆T of DyAG is 1.27 times larger than that of GdGG when T = 11 K and H e = 1 T. However, it changes to 1.15 times that of GdGG when T =16 K and H e =2 T. There are differences between the refrigerative properties of DyAG and GdGG when they are in different external magnetic fields and different temperature regions. At low temperature s(T < 10 K), the DyAG is a good magnetic refrigerative material in the lower external magnetic field. However, When H e is higher, GdGG is a good selection. This study is helpful to select suitable materials for the magnetic refrigeration technology.

  20. Analysis of emission of Eu3+ and Dy3+ doped Magnesium Boro-Tellurite (MBT ceramics

    Directory of Open Access Journals (Sweden)

    Bohari Nur Zu Ira

    2015-03-01

    Full Text Available Rare earth (RE ions play an important role in the improvement of the optical properties of ceramics. Rare-earth ceramics are commonly used in display panels, fluorescent lamps and lasers. The luminescence properties of Magnesium Boro-Tellurite (MBT Eu3+ and Dy3+ doped ceramics have not been reported before. Therefore, the aim of this paper is to determine the effect of different compositions on the luminescence properties of the MBT material. A series of xTeO2-(70-xB2O3-30MgO ceramics with 10 ≤ x ≤ 40 mol % doped with 1 mol % of Eu3+ and Dy3+ ions was prepared via the solid-state reaction method. The influence of various compositions on the crystalline phase and photoluminescence properties of the samples were investigated by X-ray diffraction (XRD and luminescence spectroscopy. The crystalline phases obtained in this study are Mg3(BO32, MgB4O7, Mg2B2O5, Mg(Te2O5 and MgTe3O6. It was stated that the crystalline phases have not changed as a result of doping with Eu3+ and Dy3+ ions. The emission spectra of Eu3+: MBT ceramics showed strong red emission at 612 nm due to the transition of 5D0 → 7F2 and meanwhile, the Dy3+: MBT ceramics showed a blue emission at 480 nm due to 4F9/2 → 6H15/2 transition and yellow emission at 576 nm due to 4F9/2→6H13/2 transition. Both the rare-earth doped phosphors showed bright emission.

  1. Effect of γ-radiation on thermoluminescence in rare earths doped NaMgSO4Cl material

    Science.gov (United States)

    Choubey, S. R.; Gedam, S. C.; Dhoble, S. J.

    2015-01-01

    The thermoluminescence (TL) characteristics, effect of γ-radiation on NaMgSO4Cl: X (X = Tb; Ce, Tb; Dy; Dy, Eu) and trapping parameters in TL material prepared by wet chemical synthesis (WCS) method are studied. The intensity of these phosphors is compared with TLD CaSO4: Dy phosphor. The phosphor has a simple TL glow curve structure. The phosphors NaMgSO4Cl: Tb (between the range of 257-284°C); NaMgSO4Cl: Dy (173°C) and NaMgSO4Cl: Dy, Eu (156°C) have a single prominent peak, whereas NaMgSO4Cl: Ce, Tb has two peaks located at 154°C and 233°C indicating single and double trapping sites, respectively. It is found that intensity tends to be increase with increased concentrations of the activators. The TL glow curves of the phosphors have been recorded and irradiated at a rate of 0.99 kGyh-1 for 5 Gy γ-rays dose. The paper also discusses the kinetic parameters evaluated by Chen's half width method such as activation energy E (eV) and frequency factor S (s-1).

  2. Analysis of emission of Eu3+ and Dy3+ doped Magnesium Boro-Tellurite (MBT) ceramics

    OpenAIRE

    2015-01-01

    Rare earth (RE) ions play an important role in the improvement of the optical properties of ceramics. Rare-earth ceramics are commonly used in display panels, fluorescent lamps and lasers. The luminescence properties of Magnesium Boro-Tellurite (MBT) Eu3+ and Dy3+ doped ceramics have not been reported before. Therefore, the aim of this paper is to determine the effect of different compositions on the luminescence properties of the MBT material. A series of xTeO2-(70-x)B2O3-30MgO ceramics with...

  3. THEORETICAL RESEARCH OF THE OPTICAL SPECTRA AND EPR PARAMETERS FOR Cs2NaYCl6:Dy3+ CRYSTAL

    Science.gov (United States)

    Dong, Hui-Ning; Dong, Meng-Ran; Li, Jin-Jin; Li, Deng-Feng; Zhang, Yi

    2013-09-01

    The calculated EPR parameters are in reasonable agreement with the observed values. The important material Cs2NaYCl6 doped with rare earth ions have received much attention because of its excellent optical and magnetic properties. Based on the superposition model, in this paper the crystal field energy levels, the electron paramagnetic resonance parameters g factors of Dy3+ and hyperfine structure constants of 161Dy3+ and 163Dy3+ isotopes in Cs2NaYCl6 crystal are studied by diagonalizing the 42 × 42 energy matrix. In the calculations, the contributions of various admixtures and interactions such as the J-mixing, the mixtures among the states with the same J-value, and the covalence are all considered. The calculated results are in reasonable agreement with the observed values. The results are discussed.

  4. Activation of Small Molecules by DyI_2 and Dy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    1 Results The reactivities of dysprosium diiodide and metallic dysprosium toward small molecules are discussed.For instance,DyI2-induced silyl radical reactions are described.The combination of dysprosium diiodide and dichloromethane can serve as an effective methylene transfer reagent for cyclopropanation of unfunctionalized alkenes beyond that possible with other metal-dichloromethane systems.Furthermore,we report that the combination of chlorosilane and metallic Dy can also serve as an effective prom...

  5. Murine model of TB meningitis.

    Science.gov (United States)

    Gupta, Umesh Datta; Abbas, Ali; Kashyap, Raj Pal Singh; Gupta, Pushpa

    2016-12-01

    Central nervous system (CNS) infections caused by Mycobacterium tuberculosis (MTB) are the most severe forms of extrapulmonary TB (EPTB) due to high levels of mortality and neurological morbidity. Limited studies are available on CNS-TB animal-model development, despite the steady rise in cerebral-TB cases in India over the past decade. This study describes the development of a murine model of CNS-TB using a clinical strain (C3) isolated from the cerebrospinal fluid (CSF) of CNS-TB patients. Groups of mice were infected intravenously with an MTB C3 strain isolated from the CSF of CNS-TB patients in order to mimic the dynamics of actual infection. Brain and lung tissue were evaluated for bacterial burden, as well as histopathology and surrogate markers of TB infection at 30- and 50-days post-infection. Mice infected intravenously with MTB C3 strains showed progressive development of CNS disease, with high bacillary burden in the lungs during the initial stage (30days), which eventually disseminated to the brain at a later stage (50days). All C3-infected mice showed elevated levels of mycobacterial antigens and antibodies, as well as increased T cell adenosine deaminase activity in brain homogenates, which explicitly correlated with mycobacterial load in the brain and chronic brain pathology. High mortality rates (60%) were associated with mice infected with the C3 strain as compared to those of controls. Our findings demonstrated the design of a novel murine model of CNS-TB using a C3 strain and that replicated events of EPTB dissemination. This model will promote efforts to understand the pathogenesis CNS-TB infection for development of improved therapeutic interventions in the future. Copyright © 2016.

  6. DySectAPI: Scalable Prescriptive Debugging

    DEFF Research Database (Denmark)

    Jensen, Nicklas Bo; Karlsson, Sven; Quarfot Nielsen, Niklas;

    We present the DySectAPI, a tool that allow users to construct probe trees for automatic, event-driven debugging at scale. The traditional, interactive debugging model, whereby users manually step through and inspect their application, does not scale well even for current supercomputers. While...

  7. Synthesis of RE(OH)2Cl and REOCl (RE=Eu, Tb) nanostructures

    Institute of Scientific and Technical Information of China (English)

    S. V. Mahajan; J. Hart; J. Hood; A. Everheart; M. L. Redigolo; D. S. Koktysh; E. A. Payzant; J. H. Dickerson

    2008-01-01

    Anisotropic structures, nanoneedles, and nanospindles of rare earth hydroxychloride (RE(OH)2Cl) and oxychloride (REOCl) (rare earth=Eu and Tb) were synthesized. The rare earth hydroxychloride nanostructures were formed via a thermally assisted hydrolysis of the rare-earth sesquioxide nanocrystals. The morphological evolution of the nanostructures was studied using high-resolution transmission electron microscopy and scanning electron microscopy, while the structural evolution was investigated using X-ray diffraction techniques. The thermal stability of the rare earth hydroxychlorides was investigated using thermogravimetric analysis. The rare earth oxychloride nanospindles were synthesized via a simple heat-treatment of rare earth hydroxychloride nanospindles.

  8. Study of luminescence and effect of Dy3+ on NaMgSO4 Cl:Ce chlorosulphate phosphor.

    Science.gov (United States)

    Choubey, Sureshkumar R; Gedam, Sharadkumar C; Dhoble, Sanjay J

    2014-12-01

    Chlorosulphate NaMgSO4 Cl phosphor doped with Ce(3+) and co-doped by Dy(3+) prepared by the wet chemical method was studied for its photoluminescence and thermoluminescence (TL) characteristics. The emission spectrum of Ce(3+) shows dominant peaks at 346 nm (excitation 270 nm) due to 5d → 4f transition. Efficient energy transfer occurs from Ce(3+) → Dy(3+) ions. Dy(3+) emission at 485 nm and 576 nm is due to (4)  F9/2 → (6) H15/2 and (4)  F9/2 → (6) H13/2 transitions of Dy(3+) ion respectively. The TL glow curves of NaMgSO4 Cl:Ce and Ce,Dy have been recorded for various concentrations at a heating rate of 2 °C/s irradiated by γ-rays at a dose rate of 0.995 kGy/h for 1 Gy, which peaks at about 241 °C and 247-312 °C respectively. Further, in changing the concentration level, the general structure of the intensity is found to increase. The main property of this phosphor is its sensitivity even for low concentrations of rare earth ions and low γ-ray dose. There is still scope for higher doses of γ-radiation. The phosphor presented may be used as a lamp phosphor as well as for TL studies.

  9. Crystal structure and magnetic properties of Dy{sub 11}Ni{sub 4}In{sub 9}

    Energy Technology Data Exchange (ETDEWEB)

    Tyvanchuk, Yu. [Analytical Chemistry Department, Ivan Franko National University of Lviv, Kyryla and Mephodiya 6, 79005 Lviv (Ukraine); Baran, S., E-mail: stanislaw.baran@uj.edu.pl [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, PL-30-059 Kraków (Poland); Duraj, R. [Institute of Physics, Technical University of Cracow, Podchorążych 1, PL-30-084 Kraków (Poland); Kalychak, Ya.M. [Analytical Chemistry Department, Ivan Franko National University of Lviv, Kyryla and Mephodiya 6, 79005 Lviv (Ukraine); Przewoźnik, J. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Department of Solid State Physics, al. Mickiewicza 30, 30-059 Kraków (Poland); Szytuła, A. [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, PL-30-059 Kraków (Poland)

    2014-02-25

    Highlights: • Crystal structure of the new Dy{sub 11}Ni{sub 4}In{sub 9} rare earth intermetallic is reported. • The compound shows magnetic ordering below 86 K. • Isothermal magnetization curves indicate complex magnetic properties. -- Abstract: The work reports on the crystal structure and magnetic properties of Dy{sub 11}Ni{sub 4}In{sub 9}. The compound crystallizes in the orthorhombic Nd{sub 11}Pd{sub 4}In{sub 9}-type structure (space group Cmmm) with Dy atoms occupying five nonequivalent Wyckoff positions. Temperature dependences of specific heat as well as ac and dc magnetic susceptibility show a ferromagnetic-like ordering with T{sub C} = 86 K and additional magnetic transitions at lower temperatures. The fit to the reciprocal susceptibility data above 180 K, in a paramagnetic state, follows the Curie–Weiss law and provides μ{sub eff} = 10.86 μ{sub B}/Dy-atom (close to the theoretical value of 10.65 μ{sub B} for the free Dy{sup 3+} ion) and a positive paramagnetic Curie temperature θ{sub p} = 28 K. Ni atoms are most likely nonmagnetic. The existence of a hysteresis loop below T{sub C} indicates a change of magnetic properties. The coercivity field is large at low temperatures (50 kOe at 1.9 K) and decreases gradually with increasing temperature down to 0.01 kOe at 75 K.

  10. Detectemos la TB. Tratemos la TB. Trabajemos juntos para eliminar la TB. (Find TB. Treat TB. Working together to eliminate TB.)

    Centers for Disease Control (CDC) Podcasts

    2014-02-26

    Este podcast trata sobre el Día Mundial de la Tuberculosis y el tema de los CDC para el año 2014.  Created: 2/26/2014 by National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (NCHHSTP).   Date Released: 2/26/2014.

  11. Promising therapy of XDR-TB/MDR-TB with thioridazine an inhibitor of bacterial efflux pumps

    DEFF Research Database (Denmark)

    Amaral, L; Martins, M; Viveiros, M

    2008-01-01

    Global rates of pulmonary tuberculosis (TB) continue to increase. Moreover, resistance of the causative organism Mycobacterium tuberculosis to the two most effective anti-TB medications continue to rise. Now, multi-drug resistant TB (MDR-TB) has progressed to extensively drug resistant TB (XDR-TB......) - a M. tuberculosis organism that is resistant to the most effective second line drugs available for the treatment of TB. This review provides detailed, significant evidence that supports the use of an old neuroleptic compound, thioridazine (TZ), for the management of MDR-TB and XDR-TB infections...

  12. Optical spectroscopy of rare-earth ions doped KY(WO4)2 thin films

    NARCIS (Netherlands)

    García-Revilla, S.; Valiente, R.; Romanyuk, Y.E.; Utke, I.; Pollnau, Markus

    2004-01-01

    KY(WO4)2 thin films doped with Dy3+, Tb3+, Yb3+, were grown onto KY(WO4)2 substrates using liquid-phase epitaxy. Spectroscopic investigations of the grown layers were performed. Obtained results were compared with spectra given for bulk crystals. Upconversion experiments after direct Yb3+ excitation

  13. Optical spectroscopy of rare-earth ions doped KY(WO4)2 thin films

    NARCIS (Netherlands)

    García-Revilla, S.; Valiente, R.; Romanyuk, Y.E.; Utke, I.; Pollnau, M.

    2004-01-01

    KY(WO4)2 thin films doped with Dy3+, Tb3+, Yb3+, were grown onto KY(WO4)2 substrates using liquid-phase epitaxy. Spectroscopic investigations of the grown layers were performed. Obtained results were compared with spectra given for bulk crystals. Upconversion experiments after direct Yb3+ excitation

  14. TB vaccines in clinical development

    OpenAIRE

    McShane, H; Ginsberg, AM; Ruhwald, M.; Mearns, H

    2016-01-01

    The 4th Global Forum on TB Vaccines, convened in Shanghai, China, from 21 – 24 April 2015, brought together a wide and diverse community involved in tuberculosis vaccine research and development to discuss the current status of, and future directions for this critical effort. This paper summarizes the sessions on TB Vaccines in Clinical Development, and Clinical Research: Data and Findings. Summaries of all sessions from the 4th Global Forum are compiled in a special supplement of Tuberculosi...

  15. Latent TB infection and pulmonary TB disease among patients with diabetes mellitus in Bandung, Indonesia

    NARCIS (Netherlands)

    Koesoemadinata, R.C.; McAllister, S.M.; Soetedjo, N.N.M.; Ratnaningsih, D.F.; Ruslami, R.; Kerry, S.; Verrall, A.J.; Apriani, L.; Crevel, R. van; Alisjahbana, B.; Hill, P.C.

    2017-01-01

    Background: Screening and treatment of latent TB infection (LTBI) and TB disease could reduce diabetes mellitus (DM)-associated TB. We aimed to describe the prevalence of LTBI and pulmonary TB among patients with DM in a TB-endemic setting. Methods: Patients with DM attending a hospital and

  16. Inelastic Neutron Scattering and Magnetisation Investigation of an Exchange-Coupled Dy2 SMM

    Science.gov (United States)

    Baker, Michael L.; Zhang, Qing; Sarachik, Myriam P.; Kent, Andrew D.; Chen, Yizhang; Butch, Nicholas; Pineda, Eufemio M.; McInnes, Eric

    The strong spin orbit coupling and weak crystal field energies of simple exchange-coupled rare earth SMMs makes the precise evaluation of their magnetic properties nontrivial. Here we report a detailed investigation of the single molecule magnet hqH2Dy2(hq)4(NO3)3MeOH. Inelastic neutron scattering is used to obtain direct access to several low energy crystal field excitations. The INS results display several features that are not found in earlier FIR absorption experiments, while other features found in the latter are absent. Based on the effective point charge model, numerical calculations are currently underway to resolve these apparent discrepancies using complementary magnetisation measurements to resolve the exchange between Dy ions. Work supported by ARO W911NF-13-1-1025 (CCNY) and NSF-DMR-1309202 (NYU).

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

    CERN Document Server

    Liu Xiao Yang

    2002-01-01

    Several rare-earth silicates have been synthesized at 10 GPa and 1600-1700 deg. C: a La orthosilicate (La sub 4 Si sub 3 O sub 1 sub 2) with a defect Ba sub 3 (PO sub 4) sub 2 -type, a new structure type (K) for Nd and Gd disilicates (Nd sub 2 Si sub 2 O sub 7 and Gd sub 2 Si sub 2 O sub 7) with a diorthosilicate structure, and a new structure type (L) for Dy disilicate (Dy sub 2 Si sub 2 O sub 7) with a structure containing linear triple tetrahedral groups [Si sub 3 O sub 1 sub 0], but having one in six atoms distributed with 50% occupancy over two tetrahedral positions.

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

    Energy Technology Data Exchange (ETDEWEB)

    Liu Xiaoyang; Fleet, Michael E [Department of Earth Sciences, University of Western Ontario, London, ON (Canada)

    2002-11-11

    Several rare-earth silicates have been synthesized at 10 GPa and 1600-1700 deg. C: a La orthosilicate (La{sub 4}Si{sub 3}O{sub 12}) with a defect Ba{sub 3}(PO{sub 4}){sub 2}-type, a new structure type (K) for Nd and Gd disilicates (Nd{sub 2}Si{sub 2}O{sub 7} and Gd{sub 2}Si{sub 2}O{sub 7}) with a diorthosilicate structure, and a new structure type (L) for Dy disilicate (Dy{sub 2}Si{sub 2}O{sub 7}) with a structure containing linear triple tetrahedral groups [Si{sub 3}O{sub 10}], but having one in six atoms distributed with 50% occupancy over two tetrahedral positions.

  19. Cationic methyl complexes of the rare-earth metals: an experimental and computational study on synthesis, structure, and reactivity.

    Science.gov (United States)

    Kramer, Mathias U; Robert, Dominique; Arndt, Stefan; Zeimentz, Peter M; Spaniol, Thomas P; Yahia, Ahmed; Maron, Laurent; Eisenstein, Odile; Okuda, Jun

    2008-10-20

    Synthesis, structure, and reactivity of two families of rare-earth metal complexes containing discrete methyl cations [LnMe(2-x)(thf)n]((1+x)+) (x = 0, 1; thf = tetrahydrofuran) have been studied. As a synthetic equivalent for the elusive trimethyl complex [LnMe3], lithium methylates of the approximate composition [Li3LnMe6(thf)n] were prepared by treating rare-earth metal trichlorides [LnCl3(thf)n] with 6 equiv of methyllithium in diethyl ether. Heteronuclear complexes of the formula [Li3Ln2Me9L(n)] (Ln = Sc, Y, Tb; L = Et2O, thf) were isolated by crystallization from diethyl ether. Single crystal X-ray diffraction studies revealed a heterometallic aggregate of composition [Li3Ln2Me9(thf)n(Et2O)m] with a [LiLn2Me9](2-) core (Ln = Sc, Y, Tb). When tris(tetramethylaluminate) [Ln(AlMe4)3] (Ln = Y, Lu) was reacted with less than 1 equiv of [NR3H][BPh4], the dimethyl cations [LnMe2(thf)n][BPh4] were obtained. The coordination number as well as cis/trans isomer preference was studied by crystallographic and computational methods. Dicationic methyl complexes of the rare-earth metals of the formula [LnMe(thf)n][BAr4]2 (Ln = Sc, Y, La-Nd, Sm, Gd-Lu; Ar = Ph, C6H4F-4) were synthesized, by protonolysis of either the ate complex [Li3LnMe6(thf)n] (Ln = Sc, Y, Gd-Lu) or the tris(tetramethylaluminate) [Ln(AlMe4)3] (Ln = La-Nd, Sm, Dy, Gd) with ammonium borates [NR3H][BAr4] in thf. The number of coordinated thf ligands varied from n = 5 (Ln = Sc, Tm) to n = 6 (Ln = La, Y, Sm, Dy, Ho). The configuration of representative examples was determined by X-ray diffraction studies and confirmed by density-functional theory calculations. The highly polarized bonding between the methyl group and the rare-earth metal center results in the reactivity pattern dominated by the carbanionic character and the pronounced Lewis acidity: The dicationic methyl complex [YMe(thf)6](2+) inserted benzophenone as an electrophile to give the alkoxy complex [Y(OCMePh2)(thf)5](2+). Nucleophilic addition of

  20. Supramolecular Assembly of Molecular Rare-Earth-3,5-Dichlorobenzoic Acid-2,2':6',2″-Terpyridine Materials: Structural Systematics, Luminescence Properties, and Magnetic Behavior.

    Science.gov (United States)

    Carter, Korey P; Thomas, Kara E; Pope, Simon J A; Holmberg, Rebecca J; Butcher, Ray J; Murugesu, Muralee; Cahill, Christopher L

    2016-07-18

    The syntheses and crystal structures of 16 new rare-earth (RE = La(3+)-Y(3+))-3,5-dichlorobenzoic acid-terpyridine molecular materials characterized via single-crystal and powder X-ray diffraction are reported. These 16 complexes consist of four unique structure types ranging from molecular dimers (La(3+) and Ce(3+)) to tetramers (Pr(3+)-Y(3+)) as one moves across the RE(3+) series. This structural evolution is accompanied by subsequent changes in modes of supramolecular assembly (halogen bonding, halogen-π, halogen-halogen, and π-π interactions). Solid-state visible and near-infrared lifetime measurements were performed on complexes 6 (Sm(3+)), 7 (Eu(3+)), 9 (Tb(3+)), 10 (Dy(3+)), 11 (Ho(3+)), 12 (Er(3+)), and 14 (Yb(3+)), and characteristic emission was observed for all complexes except 11. Lifetime data for 11, 12, and 14 suggest sensitization by the terpy antenna does occur in near-infrared systems, although not as efficiently as in the visible region. Additionally, direct current magnetic susceptibility measurements were taken for complexes 10 (Dy(3+)) and 12 (Er(3+)) and showed dominant ferromagnetic behavior.

  1. Photofunctional hybrids of rare earth complexes covalently bonded to ZnO core-shell nanoparticle substrate through polymer linkage.

    Science.gov (United States)

    Shao, Yan-Fei; Yan, Bing

    2012-06-28

    A novel series of multi-component hybrids are assembled based on rare earth coordinated to rare earth ion (Eu(3+), Tb(3+), Sm(3+), Dy(3+)) complex systems and ZnO nanocomposites through three different ester units (ethyl methacrylate (EMA), 2-hydroxyethyl methacrylate (HEMA) and 2,2,3,4,4,4-hexafluorobutyl methacrylate (HFMA)) as functional polymer linkages. Methacrylic-group-modified ZnO nanoparticles (designated ZnO-MAA) are synthesized based on the reaction between zinc methacrylate and LiOH with the molar ratio 1 : 3.5 via sol-gel process. The final hybrid materials are prepared by introducing rare earth complexes into ZnO-MAA matrix via addition polymerization reaction in the presence of benzoyl peroxide (BPO) as the initiator. The detailed characterization and luminescence of these hybrid materials are discussed. It is found that ZnO-MAA-HEMA/EMA/HFBMA-RE-phen hybrid systems have effective intramolecular energy transfer process and exhibit longer lifetime and higher quantum efficiency.

  2. Evolution with applied field of the magnetic structure of TbNiAl{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    White, R., E-mail: Reyner.White@student.adfa.edu.au; Hutchison, W. D. [The University of New South Wales, School of Physical, Environmental and Mathematical Sciences (Australia); Goossens, D. J. [Australian National University, Research School of Chemistry (Australia); Studer, A. J. [Bragg Institute, Australian Nuclear Science and Technology Organisation (Australia); Nishimura, K. [University of Toyama, Graduate School of Science and Engineering (Japan)

    2015-04-15

    Neutron powder diffraction data of TbNiAl{sub 4} has been re-examined using a representational analysis, allowing a new model of the magnetic structure to be deduced. The basis vectors obtained describe an ‘elliptical helix’ type structure in which the moments rotate in the ab-plane as one moves along the c-axis. This new model has been used to simulate the expected result of a Low Temperature Nuclear Orientation (LTNO) experiment involving 299 keV gamma-ray emission from the {sup 160}Dy daughter of aligned {sup 160}Tb nuclei. Results of the simulation along the a-axis appear to partly match currently existing experimental data, with good agreement in the magnitude of lost anisotropy.

  3. Synthesis and Structures of A Series of Novel Rare Earth Transition Metal Sulfates

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Seven new rare earth transition metal sulfates were synthesized by hydrothermal reactions under conditions slightly above the critical point of water. Their crystal structures were determined from single crystal X-ray data. The compositions of the new compounds can be represented by two general formulae: REM(OH)3(SO4) and RE2M(OH)3(SO4)2F(H2O) with RE=Gd, Tb, Dy; M=Ni, Cu. Three different crystal structure types were found for the formula REM(OH)3(SO4). The structures of the new compounds all feature infinite chains of REOn coordination polyhedra, which are connected to chains of CuO6 or NiO6 octahedra. The limited size range of the rare earth cations observed in these compounds is most likely because of interactions between the octahedral chains and the chains of REOn polyhedra. The new compounds are closely related to the known yttrium transition metal sulfates.

  4. Crystallographic superstructure in R2PdSi3 compounds (R=heavy rare earth)

    Science.gov (United States)

    Tang, Fei; Frontzek, Matthias; Dshemuchadse, Julia; Leisegang, Tilmann; Zschornak, Matthias; Mietrach, Robert; Hoffmann, Jens-Uwe; Löser, Wolfgang; Gemming, Sibylle; Meyer, Dirk C.; Loewenhaupt, Michael

    2011-09-01

    The R2PdSi3 intermetallic compounds have been reported to crystallize in a hexagonal AlB2-derived structure, with the rare earth atoms on the Al sites and Pd and Si atoms randomly distributed on the B sites. However, the intricate magnetic properties observed in the series of compounds have always suggested complications to the assumed structure. To clarify the situation, x-ray and neutron diffraction measurements were performed on the heavy rare earth compounds with R=Gd, Tb, Dy, Ho, Er, Tm, which revealed the existence of a crystallographic superstructure. The superstructure features a doubled unit cell in the hexagonal basal plane and an octuplication along the perpendicular c direction with respect to the primitive cell. No structural transition was observed between 300 and 1.5 K. Extended x-ray absorption fine structure (EXAFS) analysis as well as density functional theory (DFT) calculations were utilized to investigate the local environments of the respective atoms. In this paper the various experimental results will be presented and it will be shown that the superstructure is mainly due to the Pd-Si order on the B sites. A structure model will be proposed to fully describe the superstructure of Pd-Si order in R2PdSi3. The connection between the crystallographic superstructure and the magnetic properties will be discussed in the framework of the presented model.

  5. Separation and Recycling for Rare Earth Elements by Homogeneous Liquid-Liquid Extraction (HoLLE Using a pH-Responsive Fluorine-Based Surfactant

    Directory of Open Access Journals (Sweden)

    Shotaro Saito

    2015-08-01

    Full Text Available A selective separation and recycling system for metal ions was developed by homogeneous liquid-liquid extraction (HoLLE using a fluorosurfactant. Sixty-two different elemental ions (e.g., Ag, Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Hg, Ho, In, Ir, La, Lu, Mg, Mn, Mo, Nb, Nd, Ni, Os, P, Pb, Pd, Pr, Pt, Re, Rh, Ru, Sb, Sc, Se, Si, Sm, Sn, Sr, Ta, Tb, Te, Ti, Tl, Tm, V, W, Y, Yb, Zn, and Zr were examined. By changing pH from a neutral or alkaline solution (pH ≥ 6.5 to that of an acidic solution (pH < 4.0, gallium, zirconium, palladium, silver, platinum, and rare earth elements were extracted at >90% efficiency into a sedimented Zonyl FSA® (CF3(CF2n(CH22S(CH22COOH, n = 6–8 liquid phase. Moreover, all rare earth elements were obtained with superior extraction and stripping percentages. In the recycling of rare earth elements, the sedimented phase was maintained using a filter along with a mixed solution of THF and 1 M sodium hydroxide aqueous solution. The Zonyl FSA® was filtrated and the rare earth elements were recovered on the filter as a hydroxide. Furthermore, the filtrated Zonyl FSA was reusable by conditioning the subject pH.

  6. Thermochromism and fluorescence in dyed PEO films

    Energy Technology Data Exchange (ETDEWEB)

    Kamath, Archana; S, Raghu; V, Mini; C, Sharanappa; H, Devendrappa, E-mail: dehu2010@gmail.com [Dept. of Physics, Mangalore University, Managalagangothri, Mangalore--574199 (India)

    2015-06-24

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

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

    OpenAIRE

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

    2013-01-01

    Transparent glass-ceramic containing rare-earth doped halide nanocrystals exhibits enhanced luminescence performance. In this study, a glass-ceramic with Tb doped gadolinium fluoride nanocrystals embedded in an aluminosilicate glass matrix is investigated for X-ray imaging applications. The nanocrystalline glass-ceramic scintillator was prepared by a melt-quench method followed by an anneal. The GdF3:Tb nanocrystals precipitated within the oxide glass matrix during the processing and their lu...

  8. TB deaths reach historic levels. International (global).

    Science.gov (United States)

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

  9. The melting diagram of the Ti-Dy-Si system in the Ti-Ti{sub 5}Si{sub 3}-Dy{sub 5}Si{sub 3}-Dy region

    Energy Technology Data Exchange (ETDEWEB)

    Fartushna, Yu. [Frantsevich Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 3 Krzhizhanovsky Street, 03142 Kiev (Ukraine)], E-mail: julia@ipms.kiev.ua; Meleshevich, K.; Samelyuk, A.; Bulanova, M. [Frantsevich Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 3 Krzhizhanovsky Street, 03142 Kiev (Ukraine)

    2009-04-03

    The phase equilibria in the Ti-Ti{sub 5}Si{sub 3}-Dy{sub 5}Si{sub 3}-Dy part of the Ti-Dy-Si system were studied by DTA, X-ray diffraction, metallography and EPMA. The melting diagram, isopleths at 5Si, 65Ti and 65Dy, and a reaction scheme were constructed. The solidus surface is characterized by the following three-phase fields: <{beta}-Ti> + + DySi>, <{beta}-Ti> + DySi> + <{alpha}-Dy>, DySi> + <{alpha}-Dy> + <Dy{sub 5}Si{sub 3}>, and + DySi> + <Dy{sub 5}Si{sub 3}>. The first two fields form via U-type equilibria, L + {r_reversible} <{beta}-Ti> + DySi> and L + <{beta}-Ti> {r_reversible} DySi> + <{alpha}-Dy>, at 1320 and 1170 deg. C, respectively. The third three-phase field results from an invariant eutectic four-phase equilibrium, L {r_reversible} DySi> + <{alpha}-Dy> + <Dy{sub 5}Si{sub 3}>, at 1157 {+-} 6 deg. C. The fourth one is the result of a P-type equilibrium, L + + <Dy{sub 5}Si{sub 3}> {r_reversible} DySi>. The temperature of the latter was estimated to be within the interval 1650-1700 deg. C.

  10. WHO's End TB Strategy: From stopping to ending the global TB epidemic.

    Science.gov (United States)

    Uplekar, Mukund; Raviglione, Mario

    2015-10-01

    The 67th World Health Assembly of 2014 adopted the "End TB Strategy" with a vision of making the world free of tuberculosis (TB) and with the goal of ending the global TB epidemic by the year 2035. World Health Organization's "End TB Strategy" captures this holistic response in its four principles and three pillars. The three high-level indicators of the "End TB Strategy" - reductions in TB deaths, reductions in the TB incidence rate and the percentage of TB patients and their households experiencing catastrophic costs - are relevant to all countries. Copyright © 2016. Published by Elsevier B.V.

  11. High-field magnetization of dilute rare earths in yttrium

    DEFF Research Database (Denmark)

    Touborg, P.; Høg, J.; Cock, G. J.;

    1974-01-01

    Magnetization measurements have been performed on single crystals of Y containing small amounts of Tb, Dy, or Er at 4.2 K in fields up to 295 × 105 A/m (370 kOe). Crystal-field and molecular-field parameters obtained from measurements of the initial susceptibility versus temperature give...... a satisfactory quantitative account of the high-field magnetization. This includes characteristic features due to the crossing and mixing of crystal-field levels....

  12. Instability of the Characteristic Emissions of Dopant Tb in ZnO Hexagonal Pyramids

    Science.gov (United States)

    Zhai, Bao-gai; Ma, Qing-lan; Huang, Yuan Ming

    2017-02-01

    Tb-doped ZnO hexagonal pyramids with the doping level of 0.1 mol.% were synthesized by thermal decomposing the mixture of zinc nitrate and terbium nitrate at 500°C in an air-filled furnace. The crystal structures and photoluminescent properties of Tb-doped ZnO hexagonal pyramids were analyzed with a scanning electron microscope, x-ray diffractometer, fluorescence spectrophotometer and photoluminescence excitation spectrophotometer. Four characteristic emission peaks of Tb3+ ions were recorded over the broad green luminescent band of ZnO, at 488 nm, 544 nm, 584 nm and 620 nm for Tb-doped ZnO hexagonal pyramids. The characteristic emissions of the rare-earth dopant in Tb-doped ZnO were found to be unstable when stored in air. The 544-nm emission of dopant Tb in ZnO lost 12%, 37%, 78%, and 100% of its original intensity after stored in air for 2 months, 4 months, 6 months, and 8 months, respectively. With the help of calculated band structures, our results suggest that the instability of the characteristic emissions of dopant Tb in ZnO can be attributed to the possible expulsion of Tb out of the ZnO host.

  13. Instability of the Characteristic Emissions of Dopant Tb in ZnO Hexagonal Pyramids

    Science.gov (United States)

    Zhai, Bao-gai; Ma, Qing-lan; Huang, Yuan Ming

    2016-10-01

    Tb-doped ZnO hexagonal pyramids with the doping level of 0.1 mol.% were synthesized by thermal decomposing the mixture of zinc nitrate and terbium nitrate at 500°C in an air-filled furnace. The crystal structures and photoluminescent properties of Tb-doped ZnO hexagonal pyramids were analyzed with a scanning electron microscope, x-ray diffractometer, fluorescence spectrophotometer and photoluminescence excitation spectrophotometer. Four characteristic emission peaks of Tb3+ ions were recorded over the broad green luminescent band of ZnO, at 488 nm, 544 nm, 584 nm and 620 nm for Tb-doped ZnO hexagonal pyramids. The characteristic emissions of the rare-earth dopant in Tb-doped ZnO were found to be unstable when stored in air. The 544-nm emission of dopant Tb in ZnO lost 12%, 37%, 78%, and 100% of its original intensity after stored in air for 2 months, 4 months, 6 months, and 8 months, respectively. With the help of calculated band structures, our results suggest that the instability of the characteristic emissions of dopant Tb in ZnO can be attributed to the possible expulsion of Tb out of the ZnO host.

  14. Reversing ferroelectric polarization in multiferroic DyMn{sub 2}O{sub 5} by nonmagnetic Al substitution of Mn

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Z. Y.; Liu, M. F.; Li, X.; Wang, J. X.; Yan, Z. B.; Wang, K. F.; Liu, J.-M. [Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China)

    2014-08-07

    The multiferroic RMn{sub 2}O{sub 5} family, where R is rare-earth ion or Y, exhibits rich physics of multiferroicity which has not yet well understood. DyMn{sub 2}O{sub 5} is a representative member of this family. The ferroelectric polarization of DyMn{sub 2}O{sub 5} is claimed to be magnetically relevant and have more than one component. Therefore, the polarization reversal upon the sequent magnetic transitions is expected. We investigate the evolution of the ferroelectric polarization upon a partial substitution of Mn{sup 3+} by nonmagnetic Al{sup 3+} in order to tailor the Mn{sup 3+}-Mn{sup 4+} interactions and then to modulate the polarization in DyMn{sub 2−x/2}Al{sub x/2}O{sub 5}. It is revealed that the polarization can be successfully reversed by Al-substitution via substantially suppressing the Mn{sup 3+}-Mn{sup 4+} interactions, while the Dy{sup 3+}-Mn{sup 4+} interactions can sustain against the substitution until a level as high as x = 0.2. In addition, the independent Dy spin ordering is shifted remarkably down to an extremely low temperature due to the Al{sup 3+} substitution. The present work unveils the possibility of tailoring the Mn{sup 3+}-Mn{sup 4+} and Dy{sup 3+}-Mn{sup 4+} interactions independently, and thus reversing the ferroelectric polarization.

  15. A Novel Ce3+/Tb3+ Codoped Phosphate Glass as Down-Shifting Materials for Enhancing Efficiency of Solar Cells

    Institute of Scientific and Technical Information of China (English)

    HE Dong-Bing; YU Chun-Lei; CHENG Ji-Meng; LI Shun-Guang; HU Li-Li

    2010-01-01

    @@ For the purpose of improving conversion effciency of solar cells by applying the effect of the wavelength conversion of rare earth ions,photo-luminescence and excitation spectrums of Ce3+-Tb3+ doped phosphate glass are investigated.Results show that incorporating Cea+ ions to Tb3+-doped phosphate glass can greatly increase the absorption coefficient in the range 300-400 nm and then the energy transfer (ET) from Ce3+ to Tb3+ occurs.In addition,increasing Tb3+ concentration in Ce3+ /Tb3+ co-doped phosphate glass can greatly enhance the ET efffciency and 545 nm emission intensity.This shows that Ce3+ /Tb3+ co-doped phosphate glass would be a promising down-shifting material for enhancing the efficiency of solar cells.

  16. Biomarkers of latent TB infection

    DEFF Research Database (Denmark)

    Ruhwald, Morten; Ravn, Pernille

    2009-01-01

    For the last 100 years, the tuberculin skin test (TST) has been the only diagnostic tool available for latent TB infection (LTBI) and no biomarker per se is available to diagnose the presence of LTBI. With the introduction of M. tuberculosis-specific IFN-gamma release assays (IGRAs), a new area...... of in vitro immunodiagnostic tests for LTBI based on biomarker readout has become a reality. In this review, we discuss existing evidence on the clinical usefulness of IGRAs and the indefinite number of potential new biomarkers that can be used to improve diagnosis of latent TB infection. We also present...... early data suggesting that the monocyte-derived chemokine inducible protein-10 may be useful as a novel biomarker for the immunodiagnosis of latent TB infection....

  17. Analyses of crystal field and exchange interaction of Dy3Ga5O12 under extreme conditions

    Institute of Scientific and Technical Information of China (English)

    Wang Wei; Qi Xin; Yue Yuan

    2011-01-01

    This paper theoretically investigates the effects of crystal field and exchange interaction field on magnetic properties in dysprosium gallium garnet under extreme conditions (low temperatures and high magnetic fields) based on quantum theory. Here, five sets of crystal field parameters are discussed and compared. It demonstrates that, only considering the crystal field effect, the experiments can not be successfully explained. Thus, referring to the molecular field theory,an effective exchange field associated with the Dy-Dy exchange interaction is further taken into account. Under special consideration of crystal field and the exchange interaction field, it obtains an excellent agreement between the theoretical results and experiments, and further confirms that the exchange interaction field between rare-earth ions has great importance to magnetic properties in paramagnetic rare-earth gallium garnets.

  18. Raman Active Phonons in RCoO3 (R=La, Ce, Pr, Nd, Sm, Eu, Gd, and Dy) Perovskites

    Institute of Scientific and Technical Information of China (English)

    WANG Wei-Ran; XU Da-Peng; SU Wen-Hui; DING Zhan-Hui; XUE Yan-Feng; SONG Geng-Xin

    2005-01-01

    @@ We examine RCoO3 (R=La, Ce, Pr, Nd, Sm, Eu, Gd, and Dy) perovskites prepared with the solid-state reaction method by Raman spectroscopy, and report the Raman active phonons in the RCoO3 perovskites crystallized in cubic symmetry for RCoO3 (R=La, Ce, Pr and Nd) and orthorhombic symmetry for RCoO3 (R=Sm, Eu, Gd,and Dy). It is found that the Raman spectra of RCoO3 perovskites are strongly dependent on the ionic radius.of the rare earth elements, and the frequency shift of the most intense modes of the orthorhombic samples are correlated with some structural parameters such as Co-O bond distances, ionic radius of the rare earth elements and Jahn-Teller distortion. It is clear that Raman spectroscopy has the advantage of sensitivity to structure distortion and oxygen motion.

  19. Magnetic ordering of Hf3Ni2Si3-type {Sm, Tb, Er}3Co2Ge3 and {Tb, Ho}3Ni2Ge3 compounds

    Science.gov (United States)

    Morozkin, A. V.; Yapaskurt, V. O.; Nirmala, R.; Quezado, S.; Malik, S. K.; Mozharivskyj, Y.; Isnard, O.

    2017-02-01

    The magnetic ordering of Hf3Ni2Si3-type {Sm, Tb, Er}3Co2Ge3 and {Tb, Ho}3Ni2Ge3 compounds (space group Cmcm, oC32) was investigated via magnetization measurements and neutron diffraction study in a zero-applied field. {Sm, Tb, Er}3Co2Ge3 and Ho3Ni2Ge3 exhibit field sensitive complex antiferromagnetic orderings with TN=51 K, Tm=10 K for Sm3Co2Ge3, TN=34 K, Tm=13 K for Tb3Co2Ge3, TN=7 K for Er3Co2Ge3 and TN=11 K for Ho3Ni2Ge3. At 2 K and above the critical field of 5 kOe, 20 kOe, 4 kOe and 7 kOe for Sm3Co2Ge3, Tb3Co2Ge3, Er3Co2Ge3 and Ho3Ni2Ge3, respectively, saturation magnetizations per rare-earth atom are 6.5 μB for Tb3Co2Ge3, 7.0 μB for Er3Co2Ge3 and 8.0 μB for Ho3Ni2Ge3 in the field of 140 kOe, whereas magnetization of Sm3Co2Ge3 has an antiferromagnetic behaviour. The isothermal magnetic entropy change, ΔSm, indicates a field-induced ferromagnetic ordering in Sm3Co2Ge3, Tb3Co2Ge3, Er3Co2Ge3 and Ho3Ni2Ge3 with a maximal ΔSm value of -10.9 J/kg K for Ho3Ni2Ge3 at 11 K for a field change of 50 kOe. In a zero-applied magnetic field, below TN=33 K and down to TmND=15 K Tb3Ni2Ge3 shows an ac-antiferromagnetic ordering with the C2‧/c magnetic space group, a K0=[0, 0, 0] propagation vector and a aTb3Ni2Ge3×bTb3Ni2Ge3×cTb3Ni2Ge3 magnetic unit cell. Below TmND=15 K, its magnetic structure is a sum of the ac-antiferromagnetic component with the C2‧/c magnetic space group of the K0 vector and a sine-modulated a-antiferromagnetic component of the K1=[0, 0, ±1/3] propagation vector (the magnetic unit cell is aTb3Ni2Ge3×bTb3Ni2Ge3×3cTb3Ni2Ge3). The magnetic structure is made from the 'Tb2 - 2Tb1‧ clusters of the Tb1 8f and Tb2 4c sublattices with a dominant role of the Tb2 sublattices in the magnetic ordering of Tb3Ni2Ge3.

  20. Microcalorimetric Studies on Influence of Sm3+, Dy3+ on Growth and Sporulation of Bacillus thuringiensis

    Institute of Scientific and Technical Information of China (English)

    赵儒铭; 刘义; 杨昌英; 谢志雄; 沈萍; 屈松生

    2004-01-01

    By using an LKB-2277 Bioactivity Monitor and cycle-flow method, the thermogenic curves of aerobic growth for Bacillus thuringiensis cry Ⅱ strain at 28 ℃ have been obtained. The metabolic thermogenic curves of Bt cry Ⅱ contain two distinct parts: the first part reflects the changes of bacterial growth phase and the second part corresponds to sporulation phase. From these thermogenic curves in the absence or presence of Sm3+, Dy3+ ions, the thermokinetic parameters such as the growth rate constants k, the interval time τI, the maximum power PMAxl and heat-output QLoG for log phase, the maximum power PMAX2 and heat-output QSTAT for stationary phase, the heat-output QSPOR for sporulation phase and total heat effects QT were calculated. Sm3+ and Dy3+ ions have promoting action on the growth of Bt cry Ⅱ in their lower concentration range, on the other hand, they have inhibitory action on the sporulation of Bt in their higher concentration range. It has also been found that the effects of Sm3+ and Dy3+ ions on Bt during the sporulation phase were far greater than those during the bacterial growth phase. It was concluded that the application of Bt for controlling insecticide could not be affected by the presence of the rare-earth elements in the environmental ecosystem.

  1. Thermoluminescence Response of Gamma Irradiated SrAl2O4:Eu2+/Dy3+ Nanophosphor

    Science.gov (United States)

    Bedyal, A. K.; Kumar, Vinay; Lochab, S. P.; Singh, Fouran; Ntwaeaborwa, O. M.; Swart, H. C.

    In this paper, we report on the thermoluminescence response of nanocrystalline co-doped alkaline earth aluminates synthesized by combustion method using metal nitrate as precursor and urea as fuel. A broad TL glow peak was observed at 367 K with a shoulder at 400K. TL Anal program has been used for GCD curve fitting. The Kinetic parameters like, the activation energy (Eα), the frequency factor (s) and the order of kinetics were calculated for the SrAl2O4: Eu2+, Dy3+nanophosphors. The best dopants combination was Eu (1 mol%) and Dy (2 mol%). The samples were irradiated with γ-dose in the range 20Gy-800Gy, at room temperature. A shift from 367 K to 376 K was also observed in the main peak with an increase in irradiation dose which suggest that the irradiation doses affect the distributions of traps produced by the gamma-ray irradiations. Kinetic parameters also suggest that TL glow curve in SrAl2O4: Eu2+, Dy3+ nanophosphors is obeying second order kinetics. The nanophosphors show linear response with dose.

  2. Search for and study of linking transitions between super- and normal deformed wells in the {sup 151}Tb nucleus; Recherche et etude de transitions de liaison entre les puits super- et normalement deformes dans le noyau {sup 151}Tb

    Energy Technology Data Exchange (ETDEWEB)

    Robin, J

    2003-12-01

    While the superdeformation phenomenon has been observed many times in different mass regions, the excitation energy and angular momentum are not known for most of the superdeformed bands, mainly in the A {approx} 150 mass region. We have thus undertaken the search for and study of linking transitions between super and normal deformed potential wells in the Tb{sup 151} nucleus with the EUROBALL-IV spectrometer based at the subatomic research institute of Strasbourg. This nucleus presents the peculiarity of having an excited superdeformed band identical to the yrast one of Dy{sup 152}, which has recently been linked to normal deformed states. As the Dy{sup 152} nucleus exhibits a shape coexistence in the first potential well, we have also searched for collective rotational bands with prolate but moderate shape, coexisting with the oblate structure of Tb{sup 151}. The discovery of new superdeformed bands in the Tb{sup 151,152} isotopes, the extension to lower and higher spins of the previously known bands, and mean field calculations with a deformed Woods-Saxon potential have contributed to improve our knowledge as well as raise new questions on the orbitals configuration assignments of these bands. (author)

  3. Studies on the Synthesis, Characterization and Antibacterial Activity of Rare Earth Complexes with Schiff Base Derived from o-Vanillin and Adamantaneamine%金刚烷胺邻香兰素Schiff碱稀土配合物的合成、表征及抗菌活性研究

    Institute of Scientific and Technical Information of China (English)

    赵国良; 张萍华; 冯云龙

    2005-01-01

    The new solid complexes [LnL2(NO3)2]NO3 (L=C18H23NO2, N-2-hydroxy-3-methoxy-benzaldehyde-1-aminoadamanantane, Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y) of rare earth nitrates with Schiff base derived from o-vanillin and adamantaneamine have been synthesized in non-aqueous system and characterized by elemental analysis, molar conductance, infrared spectra,1H NMR spectra, thermal analysis. The coordination modes of the bonding in these complexes were discussed and the possible structure were proposed.Every central Ln(m) ion in the complexes coordinates with both two Schiff base ligands via four oxygen atoms of the phenol hydroxy groups and methoxy groups and two nitrates via their four oxygen atoms. Their coordination numbers are eight. In addition, the antibacterial activity of the Schiff base ligand and the complexes were studied.

  4. Extensively Drug-Resistant TB

    Centers for Disease Control (CDC) Podcasts

    2016-12-16

    Dr. Charlotte Kvasnovsky, a surgery resident and Ph.D. candidate in biostatistics, discusses various types of drug resistance in TB patients in South Africa.  Created: 12/16/2016 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 12/16/2016.

  5. TB in Wild Asian Elephants

    Centers for Disease Control (CDC) Podcasts

    2017-05-10

    Dr. Susan Mikota, co-founder of Elephant Care International, discusses TB in wild Asian elephants.  Created: 5/10/2017 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 5/10/2017.

  6. TB Anywhere Is TB Everywhere: The Intersection of U.S. Immigration Enforcement Policy and TB

    Science.gov (United States)

    2016-09-01

    partial fulfillment of the requirements for the degree of MASTER OF ARTS IN SECURITY STUDIES (HOMELAND SECURITY AND DEFENSE) from the NAVAL...30 2. Tuberculosis in Mexico ................................................................32 3. Tuberculosis in El Salvador...enforcement priorities. The incidence of TB along the U.S. border with Mexico is higher than the general rate for either country, and incarcerated

  7. [Synthesis and fluorescence properties of SrZn(WO4)2:Tb3+, Ce3+ phosphors].

    Science.gov (United States)

    Wu, Wen; Yin, Jiang-Long; Xuan, Ya-Wen; Zhang, Xin-Lei; Liu, Chun-Xia; Wang, Zhen-Ling

    2014-01-01

    SrZn(1-x) (WO4)2:xTb3+, yCe3+ green fluorescent phosphors for near ultraviolet excitation were prepared using chemical co-precipitation. The phases of different doping ratio samples were characterized by the X-ray diffraction (XRD). The emission spectrum and excitation spectrum of samples were characterized by fluorescence spectroscopy (PL). The luminescence properties of the rare-earth Tb3+ ion doped and Ce3+ and Tb3+ ion codoped samples were discussed. XRD analysis shows that the main diffraction peaks of samples were consistent with the standard card (JCPDS 08-0490 and the JCPDS 15-0774) of the diffraction peak data. This showed that the doping rare earth ions did not change matrix lattice structure. The excitation spectrum showed that the excitation spectrum peaks at 223 nm which is assigned to the 7F-7D absorption transitions of Tb3+. The emission spectrum excited by 223 nm exhibits sharp lines peaking at 543 nm which was assigned to the 5D4-7F5 transitions of the Tb3+ ions. With Tb3+ and Ce3+ co-doping, the spectrum didn't change much. The intensity of fluorescence reached the strongest when the concentration of Tb3+:Ce3+ arrived at 0.06:0.02 which may means that there was energy transfer between the ions of Ce3+ and Tb3+.

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

    Science.gov (United States)

    Chowdhury, Ataur

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

  9. COLOR STABILITY OF NATURALLY DYED DENIM FABRICS

    Directory of Open Access Journals (Sweden)

    SUBTIRICA Adriana-Ioana

    2014-05-01

    Full Text Available The desire to colour textiles is as old as spinning and weaving. Natural dyes have been used since thousands of years for their long endurance, soft and elegant colours. But the invention of synthetic dyes has limited the application of natural dyes. The health hazards associated with the use of synthetic dyes and also the increased environmental awareness have revived the use of natural dyes during the recent years. The major performance characteristic of a dye is its ability to maintain the colour in normal use and is known as colorfastness. The study provides information regarding colour fastness properties of naturally dyed denim fabrics. Three vegetable materials were used for dyeing denim fabrics: Punica granatum (bark powder, Indigofera tinctoria (leave powder and Juglans regia (walnut dried shells. The results of the study indicated that using Walnut shells and Punica granatum deeper and more stable shades of colors are obtained in comparison with Indigofera Tinctoria dyed denim samples. All samples highlight a change in color in the sense of fading which has occurred to the highest extent when exposed to artificial light and washing. When tested against water, alkaline and acid perspiration, it is noticed that better results are obtained, and color change appear in a smaller extent.

  10. Structural and optical characteristics of Ce, Nd, Gd, and Dy-doped Al2O3 thin films

    Science.gov (United States)

    Varpe, Ashwini S.; Deshpande, Mrinalini D.

    2017-07-01

    We present the optical properties of rare earth (RE)-doped Al_2O_3 thin films and discuss their possible use in applications like gate dielectric material and in coating industry. Aluminum oxide films doped with RE elements such as Ce, Nd, Gd, and Dy are synthesized on glass substrate using ultrasonic spray pyrolysis technique at 400°C. The concentration of rare earth element is varied from 0.5 to 5 mol% in 0.1 M solution of Al2O3. The X-ray diffraction analysis indicates that the thin films deposited with and without rare earth doping have an amorphous structure. Further, the optical properties of RE-doped Al2O3 thin films are studied by using UV-visible spectroscopy and photoluminescence measurement. The band gap is found to be 4.06 eV for Al2O3 thin film. A small blue shift is seen in the optical spectra of RE-doped samples as compared to undoped Al2O3 film. Dielectric constant of alumina thin film increases with doping of Gd and Dy while it decreases with Ce and Nd doping. Concentration quenching effects are observed in the photoluminescence spectra of Ce, Nd, Gd, and Dy-doped Al_2O_3 films. Among all these RE-doped Al2O3 thin films, Gd and Dy-doped Al2O3 films exhibit a potential for the construction of dielectric gate in transistors or as a coating material in the semiconductor industry.

  11. Structural and optical characteristics of Ce, Nd, Gd, and Dy-doped $\\rm{Al_{2}O_{3}}$ thin films

    Indian Academy of Sciences (India)

    ASHWINI S VARPE; MRINALINI D DESHPANDE

    2017-07-01

    We present the optical properties of rare earth (RE)-doped $\\rm{Al_{2}O_{3}}$ thin films and discuss their possible use in applications like gate dielectric material and in coating industry. Aluminum oxide films doped with RE elements such as Ce, Nd, Gd, and Dy are synthesized on glass substrate using ultrasonic spray pyrolysis technique at 400$^{\\circ}$C. The concentration of rare earth element is varied from 0.5 to 5 mol% in 0.1 M solution of $\\rm{Al_{2}O_{3}}$. The X-ray diffraction analysis indicates that the thin films deposited with and without rare earth doping have an amorphous structure. Further, the optical properties of RE-doped $\\rm{Al_{2}O_{3}}$ thin films are studied by using UV–visible spectroscopy and photoluminescence measurement. The band gap is found to be 4.06eV for $\\rm{Al_[2}O_{3}}$ thin film. A small blue shift is seen in the optical spectra of RE-doped samples as compared to undoped $\\rm{Al_[2}O_{3}}$ film. Dielectric constant of alumina thin film increases with doping of Gd and Dy while it decreases with Ce and Nd doping. Concentration quenching effects are observed in the photoluminescence spectra of Ce, Nd, Gd, and Dy-doped $\\rm{Al_[2}O_{3}}$ films. Among all these RE-doped $\\rm{Al_[2}O_{3}}$ thin films, Gd and Dy-doped $\\rm{Al_[2}O_{3}}$ films exhibit a potential for the construction of dielectric gate in transistors or as a coating material in the semiconductor industry.

  12. Effect of anion interstitials on the thermoluminescent properties of CaSO{sub 4}:Dy

    Energy Technology Data Exchange (ETDEWEB)

    Lakshmanan, A.R., E-mail: arunachalamlakshmanan@yahoo.com; Sivakumar, V.; Sangeetha Rani, R.; Kalpana, S.

    2013-10-15

    Efforts were made to synthesise CaSO{sub 4} based thermoluminescent (TL) phosphors by solid state reaction route. ZnSO{sub 4} flux was found to be quite efficient in the incorporation of Dy into CaSO{sub 4} lattice as witnessed from the high TL intensity peak at about 100 °C following sintering at 750 °C in air. Its TL intensity is even higher than that of the 260 °C peak appearing in recrystallised CaSO{sub 4}:Dy. Similar low temperature TL peak was found in recrystallised CaSO{sub 4}:Dy samples sintered at 1000 °C in air. The results were explained on the basis of incorporation of interstitial oxygen anions which act as hole traps. Firing in sulphur or ammonium sulphate atmosphere did not shift the low temperature TL glow peak. But firing in carbon atmosphere at 750 °C with ZnSO{sub 4} flux enhanced the intensity of TL glow peaks at 250 °C and at 400 °C due to the partial re-conversion of oxygen ions to sulphate ions. Firing at 850 °C in reduced atmosphere, however, quenched the intensity of all TL peaks due to the removal of oxygen i.e. partial reduction of CaSO{sub 4} to CaS. The slow decline in the intensity of 250° TL peak on prolonged annealing at 400 °C in recrystallised CaSO{sub 4}:Dy indicates the thermal migration of defects causing the TL peak. Redox mechanism involving such interstitial ions and anion vacancies in the presence or absence of cation vacancies could lead to the emission of high (∼250 °C) or low (∼100 °C) temperature TL peaks, respectively. Certain other co-dopants tried such as Al{sup 3+} and SiO{sub 4}{sup 4−} simply quenched the TL efficiencies of CaSO{sub 4}:Dy and CaSO{sub 4}:Mn, respectively. Among the monovalent sulphates tried, Na{sub 2}SO{sub 4}:Dy gave a TL peak around 100 °C which is 20% of the 250 °C TL intensity of recrystallised CaSO{sub 4}:Dy. -- Highlights: • Effect of anion co-dopants at interstitial sites on CaSO{sub 4}:Dy is studied. • In this work ZnSO{sub 4} was used as the oxygen source since

  13. Fluorescence enhancement of Tb(Ⅲ) complex with a new β-diketone ligand by 1,10-phenanthroline

    Institute of Scientific and Technical Information of China (English)

    JIU Hongfang; LIU Guode; ZHANG Zhijing; FU Yuehua; CHEN Jianchao; FAN Tao; ZHANG Lixin

    2011-01-01

    A novel β-diketone,l-(3,4,5-trisbenzyloxy)benzoyl-5-benzoyl acctylacetone (TBAA),and its corresponding binary Tb(Ⅲ) complex Tb(TBAA)3·2H2O and ternary complex Tb(TBAA)3Phen with 1,10-phenanthroline (Phen) were prepared.The ligand was characterized based on elemental analysis,FT-IR,and 1H NMR.The complexes were characterized with elemental analysis,FT-IR and thermogravimetryand derivative thermogravimetry (TG-DTG).Photoluminescence measurements indicated that the energy absorbed by the organic ligand was efficiently transferred to the central Tb3+ ions,and the complex showed intense and characteristic emissions due to the 5D4→ 7FJ transitions of the central Tb3+ ions.Both complexes showed longer fluorescence lifetimes.After the introduction of the second ligand Phen group,the relative emission intensities and fluorescence lifetimes of the ternary complex Tb(TBAA)3Phen enhanced more obviously than that of the binary complex Tb(TBAA)3+2H2O.This indicated that the presence of the ligand TBAA and the second ligand Phen could sensitize fluorescence intensities of Tb(Ⅲ) iota,and the introduction of Phen group resulted in the enhancement of the fluorescence properties of the Tb(Ⅲ) ternary rare earth complex.

  14. Structural characterization and photoluminescence properties of sol–gel derived nanocrystalline BaMoO{sub 4}:Dy{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Jena, Paramananda [Department of physics, Pondicherry University, Pondicherry 605014 (India); Gupta, Santosh K., E-mail: santufrnd@gmail.com [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Natarajan, V. [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Sahu, Manjulata [Radioanalytical Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Satyanarayana, N., E-mail: nallanis2011@gmail.com [Department of physics, Pondicherry University, Pondicherry 605014 (India); Venkateswarlu, M. [R and D Amara Raja Batteries Ltd., Karakambadi 517501, A.P., India. (India)

    2015-02-15

    Nanocrystalline BaMoO{sub 4} samples doped with varying Dy{sup 3+} content were prepared by acrylamide assisted sol–gel combustion process. The prepared samples were characterized by X-ray diffraction (XRD), Fourier transform Raman spectroscopy (FT-Raman), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and photoluminescence (PL) techniques. The crystalline phase and structure of all the Dy{sup 3+} doped BaMoO{sub 4} prepared samples were confirmed from the analysis of the obtained results of XRD, FT-Raman and FTIR. The average crystallite sizes of all the prepared samples, calculated using Scherrer's formula and XRD data, were found to be less than 100 nm. Microstructures of all the prepared Dy{sup 3+} doped BaMoO{sub 4} samples were analyzed from the obtained SEM micrographs. Excitation, emission and lifetime spectroscopic studies of undoped and Dy{sup 3+} doped BaMoO{sub 4} were carried out. Effect of concentration of Dy{sup 3+} on the luminescence properties of the prepared phosphors viz. emission intensity and PL decay, was also investigated. Based on critical distance calculation, mechanism for concentration quenching was proposed. Undoped sample was found to give reddish blue emission, whereas doped samples showed yellowish white emission. - Highlights: • Characterization of BaMoO{sub 4}:Dy{sup 3+} samples by XRD, SEM, FTIR, Raman and PL. • Effect of concentration on luminescence properties. • Evidence for the presence of two rare earth ion sites in the matrix. • Near white emission from BaMoO{sub 4}:Dy{sup 3+}.

  15. Investigation of 2.9 μm luminescence properties and energy transfer in Tm3+/Dy3+ co-doped chalcohalide glasses

    Institute of Scientific and Technical Information of China (English)

    LI Zhongxiu; XU Tiefeng; SHEN Xiang; DAI Shixun; WANG Xunsi; NIE Qiuhua; ZHANG Xianghua

    2011-01-01

    A series of chalcohalide glasses based on the composition of 0.9(Ge30Ga5Se65)-0.1CsI with different Tm3+/Dy3+-codoped ions concentrations were synthesized by melt-quenching technique. The absorption spectra and 2.9 μm mid-infrared fluorescence spectra of glass samples under 800 nm laser excitation were measured. The results showed that Tm3+ was an efficient sensitizer, which could enhance the Dy3+:2.9 μm fluorescence intensity significantly. The effective energy transfer between the two rare-earth ions were mainly attributed to the resonance energy transfer from Tm3+:3F4 to Dy3+:6H1 1/2 level. Emission cross section of 2.9 μm mid-infrared luminescence was also investigated according to Judd-Ofelt theory, σe=2.51 × 10-20 cm2.

  16. Formation of ternary Mg–Cu–Dy bulk metallic glasses

    Indian Academy of Sciences (India)

    X F Wu; Y Kang; F F Wu; K Q Qiu; L K Meng

    2011-12-01

    The glass-forming ability (GFA) of ternary Mg–Cu–Dy alloys was systematically investigated by using differential scanning calorimetry (DSC) and X-ray diffractometry (XRD) techniques. The results showed that a series of ternary Mg–Cu–Dy bulk metallic glasses (BGMs) with a diameter of 4–8 mm were successfully fabricated in the system with conventional Cu-mold casting method. Mg55Cu32Dy13, Mg60Cu27Dy13, Mg65Cu25Dy10 and Mg70Cu17Dy13 BMGs exhibit a clear glass transition, a broad supercooled liquid region and different crystallization and melting behaviours. They have supercooled liquid region ($\\Delta T_{x}$) from 41 K to 65 K, reduced glass transition temperature ($T_{rg}$) from 0.5363 to 0.5974 and parameter from 0.4038 to 0.4136. The shows a relatively good agreement with the GFA of the BGMs. On the other hand, a high fracture compressive strength of 624 MPa was obtained for Mg60Cu27Dy13 BMG.

  17. Optical properties of dy doped lead and bismuth borate glasses - effect of glass composition, metal and semiconducting nanoparticles

    Science.gov (United States)

    Ooi, Hio Giap

    The optical properties of Dy3+ ions in lead borate and bismuth borate glasses are studied as a function of glass composition with PbO content (29.5 to 69.5mol%) and Bi2O3 content (29.5 to 59.5 mol%). We also studied the effect of metal and semiconducting nanoparticles on the absorption and fluorescence emission of Dy3+ ions in both lead and bismuth borate glasses. The absorption coefficient at each wavelength is obtained from the optical absorption spectrum of a glass sample, and the number density of rare-earth (RE) ions is calculated from the measurement of the glass density. These two parameters are then used to calculate the oscillator strength of each transition using Judd-Ofelt theory. Using the oscillator strength for each transition, we obtained the intensity parameters which represent changes in the symmetry of the ligand field at the Dy 3+ site (due to structural group changes and changes in Dy-O covalency). Radiative transition probabilities, the radiative lifetime of the excited states and the branching ratios are then obtained from these intensity parameters. The fluorescence spectra, obtained using 355 nm and 458 nm laser excitation, are analyzed by determining the area ratio of yellow/blue (Y/B) peaks and the wavelength of the hypersensitive transition (HST). The compositional dependence and effect of nanoparticles on the stimulated emission cross-section (sigmap), are then evaluated using radiative transition probability, the refractive index of the host glass, effective fluorescence linewidth, and the position of the band. In all of the glass systems, it was found that the optical properties are strongly influenced by structural changes arising from compositional variation and size of nanoparticles. Dy 3+ transitions exhibit large sigmap suggesting the possible utilization of these materials in laser applications.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-08-01

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

  19. Pressure and strain effects of hexagonal rare-earth manganites: a first-principles study.

    Science.gov (United States)

    Tan, Hengxin; Xu, Changsong; Li, Menglei; Wang, Shanying; Gu, Bing-Lin; Duan, Wenhui

    2016-03-31

    We have investigated the structural, electrical and magnetic properties as well as the phonon modes of hexagonal rare-earth manganites (RMnO3, R  =  Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm and Lu) under chemical pressure, hydrostatic pressure and epitaxial strain by first-principles calculations. The magnetic ground state of RMnO3 is found to have Γ4 magnetic configuration and to be stable under all considered external conditions. In contrast, the K3 phonon mode, which is the primary order parameter and responsible for the 'improper ferroelectricity', is greatly influenced by pressure and epitaxial strain. Consequently, the electric polarization is enhanced by 56.7% when the chemical pressure increases from R  =  Pr to R  =  Lu. The hydrostatic pressure can also improve the polarization to a certain degree, e.g. by 14.7% from 0 GPa to 40 GPa in LuMnO3. Finally, the dependence of polarization on the epitaxial strain is also given, revealing that the compressive strain could promote the ferroelectricity while tensile strain will suppress it.

  20. Morphological, Raman, electrical and dielectric properties of rare earth doped X-type hexagonal ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Majeed, Abdul, E-mail: abdulmajeed2276@gmail.com [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Center for Computational Materials Science, Department of Physics, University of Malakand, Chakdara, Dir (Lower) 18800 (Pakistan); Khan, Muhammad Azhar, E-mail: azhar.khan@iub.edu.pk [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Raheem, Faseeh ur [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Ahmad, Iftikhar [Center for Computational Materials Science, Department of Physics, University of Malakand, Chakdara, Dir (Lower) 18800 (Pakistan); Department of Physics, Abbottabad University of Science & Technology, Abbottabad (Pakistan); Akhtar, Majid Niaz [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Warsi, Muhammad Farooq [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan)

    2016-12-15

    The influence of rare-earth metals (La, Nd, Gd, Tb, Dy) on morphology, Raman, electrical and dielectric properties of Ba{sub 2}NiCoRE{sub x}Fe{sub 28−}xO{sub 46} ferrites were studied. The scanning electron microscopy (SEM) exhibited the platelet like structure of these hexagonal ferrites. The surface morphology indicated the formation of ferrite grains in the nano-regime scale. The bands obtained at lower wave number may be attributed to the metal-oxygen vibration at octahedral site which confirm the development of hexagonal phase of these ferrites. The resonance peaks were observed in dielectric constant, dielectric loss factor and quality factor versus frequency graphs. These dielectric parameters indicate that these ferrites nano-materials are potential candidates in the high frequency applications. The enhancement in DC electric resistivity from 2.48×10{sup 8} to 1.20×10{sup 9} Ω cm indicates that the prepared materials are beneficial for decreasing the eddy current losses at high frequencies and for the fabrication of multilayer chip inductor (MLCI) devices.

  1. Sol-gel-derived hybrid materials multi-doped with rare-earth metal ions

    Science.gov (United States)

    Zelazowska, E.; Rysiakiewicz-Pasek, E.; Borczuch-Laczka, M.; Cholewa-Kowalska, K.

    2012-06-01

    Four different hybrid organic-inorganic materials based on TiO2-SiO2 matrices with organic additives and doped with rare-earth metal ions (III) from the group of europium, cerium, terbium, neodymium, dysprosium and samarium, were synthesized by sol-gel method. Tetraethyl orthosilicate, titanium (IV) isopropoxide and organic compounds, such as butyl acrylate, butyl methacrylate, ethyl acetoacetate, ethylene glycol dimethacrylate, ethyl acetate, propylene carbonate, organic solvents and certain inorganic salts were used in the synthesis. The inorganic part of the sols, which were used in the synthesis of all the hybrid materials, was prepared separately and then the organic parts were added. The materials obtained were aged for three weeks at room temperature and then heated in an electric oven for three hours at temperatures of 80 °C-150 °C. Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM/EDX); X-ray diffraction (XRD); Fourier transform infrared spectroscopy (KBr technique); 29Si magic-angle spinning nuclear magnetic resonance; and fluorescence spectroscopy were used for the examination of morphology, microstructure and luminescence properties, respectively. Photoluminescence properties with relatively intense narrow emission lines of Tb, Eu, Dy, Nd, Sm respectively to the RE-ions doping, were observed for all the hybrid materials.

  2. Morphological, Raman, electrical and dielectric properties of rare earth doped X-type hexagonal ferrites

    Science.gov (United States)

    Majeed, Abdul; Khan, Muhammad Azhar; ur Raheem, Faseeh; Ahmad, Iftikhar; Akhtar, Majid Niaz; Warsi, Muhammad Farooq

    2016-12-01

    The influence of rare-earth metals (La, Nd, Gd, Tb, Dy) on morphology, Raman, electrical and dielectric properties of Ba2NiCoRExFe28-xO46 ferrites were studied. The scanning electron microscopy (SEM) exhibited the platelet like structure of these hexagonal ferrites. The surface morphology indicated the formation of ferrite grains in the nano-regime scale. The bands obtained at lower wave number may be attributed to the metal-oxygen vibration at octahedral site which confirm the development of hexagonal phase of these ferrites. The resonance peaks were observed in dielectric constant, dielectric loss factor and quality factor versus frequency graphs. These dielectric parameters indicate that these ferrites nano-materials are potential candidates in the high frequency applications. The enhancement in DC electric resistivity from 2.48×108 to 1.20×109 Ω cm indicates that the prepared materials are beneficial for decreasing the eddy current losses at high frequencies and for the fabrication of multilayer chip inductor (MLCI) devices.

  3. Novel phosphors of Eu3+, Tb3+ or Tm3+ activated LaBGeO5

    Institute of Scientific and Technical Information of China (English)

    ZHANG Sa; WU Genhua; DUAN Chengjun; WANG Jiao

    2011-01-01

    Rare earth borogermanates as a group of stable compounds provided various potential properties important for modem sciences.Among the properties of interests,luminescence was manifested due to the variability of rare earth elements and the compounds constituted an important group of potential candidate.In this work,novel phosphors of Eu3+,Tb3+ or Tm3+ doped LaBGeO5 with the stillwellite type structure were synthesized by the solid state reaction method.Their X-ray and UV excitation luminescent properties showed that LaBGeO5 was an excellent host lattice for the luminescence of Eu3+,Tb3+ and Tm3+.The LaBGeOs:Eu3+,LaBGeO5:Tb3+ and LaBGeOs:Tm3+ presented bright red,green and blue emission light for both UV and X-ray excitation.

  4. Excited quasiparticles and entropy in 161,162Dy

    Science.gov (United States)

    Razavi, R.; Mohassel, A. Rashed; Mohammadi, S.

    2015-11-01

    In this paper, the nuclear level densities of 161,162Dy is studied by the use of a microscopic theory which includes nuclear pairing interaction. It is based on the modified harmonic oscillator model according to the Nilsson potential. The entropy of even-odd and even-even nuclei as a function of nuclear temperature is obtained. The entropy excess of 161Dy is compared with that of 162Dy. It is concluded that the difference is related to the entropy carried by the neutron hole coupled to the even-even core. The numbers of excited quasiparticles are calculated. Good agreement was observed between calculated results and the experimental data.

  5. Luminescence behavior of Dy 3+ ions in lead borate glasses

    Science.gov (United States)

    Pisarska, Joanna

    2009-10-01

    Dy-doped lead borate glasses were studied. The luminescence spectra showed two characteristic bands at 480 and 573 nm due to 4F 9/2- 6H 15/2 (blue) and 4F 9/2- 6H 13/2 (yellow) transitions of Dy 3+. The yellow/blue luminescence of trivalent dysprosium was analyzed as a function of the B 2O 3/PbO ratios, the activator (Dy 3+) and the PbX 2 (X = F, Cl, Br) content.

  6. Probing Dy{sup 3+} magnetic moments in multiferroic perovskite DyMnO{sub 3} by optical spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kashchenko, M.A. [Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow (Russian Federation); Moscow Institute of Physics and Technology (State University), Dolgoprudnyi (Russian Federation); Klimin, S.A.; Popova, M.N. [Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow (Russian Federation); Balbashov, A.M. [Moscow Power Engineering Institute (Technical University), Moscow (Russian Federation)

    2016-06-15

    We present a detailed temperature-dependent (4-300 K) spectroscopic study of DyMnO{sub 3} single crystals with distorted perovskite structure. Energies of 36 crystal-field levels of Dy{sup 3+} in paramagnetic DyMnO{sub 3} were determined. The Dy{sup 3+} ground Kramers doublet does not split at T{sub N}{sup Mn} = 39 K and splits below T{sub lock} = 18 K. The splitting grows fast at temperatures near T{sub N}{sup Dy} = 6.5 K and reaches Δ{sub 0} ∼ 11 ± 2 cm{sup -1} at 4 K. Using the experimental temperature dependence Δ{sub 0}(T), we calculate the dysprosium magnetic moment m{sub Dy}(T) and the dysprosium contribution into specific heat and magnetic susceptibility. Analysing all the experimental data, we conclude that the Dy-Mn interaction is of the Dzyaloshinskii-Moriya type. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Magnetic Order and Spin Dynamics in a Hexagonal Rare Earth Manganite

    Science.gov (United States)

    Helton, J. S.; Singh, D. K.; Elizabeth, S.; Harikrishnan, S.; Lynn, J. W.

    2011-03-01

    Hexagonal rare earth manganites, RMn O3 R = Dy, Ho, Er, Tm, Yb, Lu, Y, or Sc), have attracted a great deal of recent attention as magnetoelectric multiferroics as most of these systems are ferroelectric at room temperature and display magnetic order below TN ~ 100 K. This magnetic order can be quite complex, as both the R and Mn ions lie on geometrically frustrated triangular lattices. DyMn O3 is typically orthorhombic, but can also be grown in the hexagonal phase; Dy 0.5 Y0.5 Mn O3 displays the hexagonal phase and is magnetically diluted at the rare earth site. We have used neutron scattering experiments to explore the magnetic structure and spin dynamics of Dy 0.5 Y0.5 Mn O3 .

  8. Synthesis and Magnetostriction of (CexTb1-x)0.5Pr0.5Fe2 Compounds

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The structural and magnetostrictive properties of (CexTb1-x)0.5Pr0.5Fe2 were investigated. Ce concentration must exceed x=0.6 in order to obtain the pure Laves phase. The magnetostriction and anisotropy constant increase with the Tb-content in this system. The anisotropy value of PrFe2 is lower than that of isostructural DyFe2. From the X-ray step-scanned data we found that λ111 of PrFe2 is 1310×10-6. A large increase of magnetostriction can be observed under a small prestress of 6 MPa for Ce0.5Pr0.5Fe2.

  9. Neutron diffraction investigations of zero-field and field-induced magnetic structures of DyNiSn single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Murogaki, K. [Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan)]. E-mail: murogaki@fiberbit.net; Kawano, S. [Research Reactor Institute, Kyoto University, Osaka 590-0494 (Japan); Andoh, Y. [Faculty of Regional Sciences, Tottori University, Tottori 680-8551 (Japan); Takahashi, M. [Institute of Materials Science, University of Tsukuba, Ibaraki 305-8573 (Japan); Kurisu, M. [Japan Advanced Institute of Science and Technology, Ishikawa 923-1292 (Japan); Nakamoto, G. [Japan Advanced Institute of Science and Technology, Ishikawa 923-1292 (Japan); Anh, D.T. Kim [Japan Advanced Institute of Science and Technology, Ishikawa 923-1292 (Japan); Tsutaoka, T. [Graduate School of Education, Hiroshima University, Hiroshima 739-8524 (Japan)

    2006-02-09

    Single crystal neutron diffraction studies have been performed on the rare-earth ternary compound, DyNiSn. This crystal exhibits an incommensurate magnetic structure expressed by the propagation vector, Q = (0.662 0.352 0) with its third harmonics at low temperatures. In an external magnetic field applied along the c-axis DyNiSn shows incommensurate modulation with Q = (1 0.315 0) at 1.6 K, while along the easy magnetization direction of the b-axis a commensurate modulation with Q = (2/3 0 0) develops at 2 K. The results along the b-axis are fully consistent with the magnetization curve.

  10. Neutron diffraction study of the magnetic long-range order in Tb

    DEFF Research Database (Denmark)

    Dietrich, O.W.; Als-Nielsen, Jens Aage

    1967-01-01

    Like other heavy rare-earth metals, Tb exhibits a magnetic phase with a spiral structure. This appears within the temperature region from 216 to 226deg K between the ferromagnetic phase and the paramagnetic phase. The transition between ferromagnetic and spiral structure is of first order and imp...

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

    Science.gov (United States)

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

    2015-09-21

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

  12. X-ray photoelectron spectroscopy and magnetism of AlDyNi, AlDyNi{sub 4} and AlDy{sub 3}Ni{sub 8} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Rednic, V; Coldea, M; Rednic, L; Pascut, L G; Pintea, S [Babes-Bolyai University, Faculty of Physics, 1 Mihail Kogalniceanu, 400084 Cluj-Napoca (Romania); Aldea, N [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania); Neumann, M, E-mail: vasile.rednic@itim-cj.r [University of Osnabrueck, Fachbereich Physik, 49069 Osnabrueck (Germany)

    2009-08-01

    The electronic and magnetic properties of AlDyNi, AlDyNi{sub 4} and AlDy{sub 3}Ni{sub 8} are studied using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), static and dynamic magnetic measurements. The three compounds AlDyNi, AlDyNi{sub 4} and AlDy{sub 3}Ni{sub 8} are single phases and crystallize in the Fe{sub 2}P, CaCu{sub 5} and CeNi{sub 3} structure types, respectively. All the investigated compounds order ferromagnetically below the corresponding Curie temperatures. The Curie temperature and the magnetic moments are 25 K and 6 {mu}{sub B}/f.u. for AlDyNi, 14 K and 6.9 {mu}{sub B}/f.u. for AlDyNi{sub 4} and 22K and 19.2 {mu}{sub B}/f.u. for AlDy{sub 3}Ni{sub 8}. At high temperature the magnetic susceptibility obey the Curie-Weiss law. The paramagnetic Curie temperature and the effective magnetic moments are 30K and 10.88 {mu}{sub B}/f.u. for AlDyNi, 28 K and 10.94 {mu}{sub B}/f.u. for AlDyNi{sub 4} and 18 K and 18.33 {mu}{sub B}/f.u. for AlDy{sub 3}Ni{sub 8}. XPS valence band and Ni 2p spectra indicated the presence of small magnetic moment on Ni sites in AlDy{sub 3}Ni{sub 8} and AlDyNi{sub 4}, and a complete filling of Ni 3d band in AlDyNi.

  13. Isothermal section at 850 °C of the Ti–Dy–Al system in the Ti–TiAl–DyAl{sub 2}–Dy region

    Energy Technology Data Exchange (ETDEWEB)

    Bulanova, M.; Fartushna, I., E-mail: juliefart@mail.ru; Meleshevich, K.; Samelyuk, A.

    2014-06-15

    Highlights: • By the character the isothermal section at 850 °C is practically similar to the solidus surface. • The phases α{sup l}, α{sub 2} and αDyAl{sub 2} define the character of phase equilibria. • Among all phases only (αDyAl{sub 2}) dissolves significant amount of third component. • The solubility of titanium in αDyAl{sub 2} is about 19 at.%. • The ternary compounds in the studied region were not found. - Abstract: Phase equilibria in the Ti–Dy–Al system in the Ti–TiAl–DyAl{sub 2}–Dy region at 850 °C were studied by the methods of X-ray diffraction, SEM and electron microprobe. The isothermal section at this temperature was constructed. The ternary compounds in the studied region were not found. The isothermal section at 850 °C is characterized by the three-phase regions α{sup l} + (αDy) + (Dy{sub 2}Al), α{sup l} + α{sub 2} + (Dy{sub 2}Al), α{sub 2} + (Dy{sub 2}Al) + (Dy{sub 3}Al{sub 2}), α{sub 2} + (Dy{sub 3}Al{sub 2}) + (αDyAl{sub 2}), (DyAl) + (αDyAl{sub 2}) + (Dy{sub 3}Al{sub 2}) and α{sub 2} + (αDyAl{sub 2}) + γ and appropriate two-phase areas.

  14. Improvement of Thermal Stability of Nd-Tb-Fe-Co-B Sintered Magnets by Additions of Pr, Ho, Al, and Cu

    Directory of Open Access Journals (Sweden)

    A. A. Lukin

    2012-01-01

    Full Text Available The present work investigates the influence of Pr, Al, Cu, B and Ho which were introduced into the Co-containing sintered magnets of Nd-Dy-Tb-Fe-Co-B type on the magnetic parameters (α, Hci, Br, BHmax⁡. The effect of heat treatment parameters on magnetic properties was also studied. It was revealed that the essential alloying of NdFeB magnets by such elements as Dy, Tb, Ho, Co as well as by boron-forming elements, for example, by titanium, may lead to reducing of F-phase quantity, and, as a consequence, to decreasing of magnetic parameters. It was also shown that additional doping of such alloys by Pr, B, Al and Cu leads to a significant increase of the quantity of F-phase in magnets as well as solubility of the Dy, Tb, Ho and Co in it. This promotes the increase of magnetic parameters. It was possible to attain the following properties for the magnets (Nd0,15Pr0,35Tb0,25Ho0,2515(Fe0,71Co0,29bal ⋅ Al0,9Cu0,1B8,5 (at. % after optimal thermal treatment {1175 K (3,6–7,2 ks with slow (12–16 ks cooling to 675 K and subsequently remaining at T=775 K for 3,6 ks—hardening}: Br=0,88 T, Hci=1760 kA/m, BHmax⁡=144 kJ/m3, α<|0,01|%/K in the temperature interval 223–323 K.

  15. Light and anoxia fading of Prussian blue dyed textiles

    National Research Council Canada - National Science Library

    Gervais, Claire; Languille, Marie-Angélique; Reguer, Solenn; Garnier, Chantal; Gillet, Martine

    2014-01-01

    .... Its stability upon exposure to light and anoxia remains difficult to apprehend. The present paper focuses on the relative influences of light, anoxia and type of substrate on the discoloration of Prussian blue dyed textiles...

  16. High-spin structure of neutron-rich Dy isotopes

    Indian Academy of Sciences (India)

    A Ansari; H L Yadav; M Kaushik; U R Jakhar

    2003-06-01

    In view of recent experimental progress on production and spectroscopy of neutron-rich isotopes of Dy with mass number = 166 and 168, we have made theoretical investigations on the structure of high spin states of 164-170Dy isotopes in the cranked Hartree–Fock–Bogoliubov (CHFB) theory employing a pairing+quadrupole+hexadecapole model interaction. With the increase of neutron number the rotation alignment of the proton orbitals dominates the structure at high spins, which is clearly reflected in the spin dependence of the rotational g-factors. A particularly striking feature is the difference in the spin-dependent properties of 166Dy as compared to that of 164Dy.

  17. Green Non-dyed Textile Innovation Alliance officially launched

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    June 29, the Green Non-dyed Textile Innovation Alliance was officially launched by the China Textile Information Center, Nationa Textile Product Development Center together with China Chemical Fiber Industry Association

  18. Why healthcare workers are sick of TB

    Directory of Open Access Journals (Sweden)

    Arne von Delft

    2015-03-01

    Full Text Available 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.

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

    Science.gov (United States)

    ... the Facts Tuberculosis - The Connection between TB and HIV 12-Dose Regimen for Latent TB Infection-Patient Education Brochure Posters Mantoux Tuberculin Skin Test Wall Chart World TB Day Think TB Stop TB Reports & Articles Morbidity and Mortality Weekly Reports (MMWRs) DTBE Authored ...

  20. Comparison of the sequence-dependent fluorescence of the cyanine dyes Cy3, Cy5, DyLight DY547 and DyLight DY647 on single-stranded DNA.

    Science.gov (United States)

    Kretschy, Nicole; Somoza, Mark M

    2014-01-01

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

  1. Comparison of the sequence-dependent fluorescence of the cyanine dyes Cy3, Cy5, DyLight DY547 and DyLight DY647 on single-stranded DNA.

    Directory of Open Access Journals (Sweden)

    Nicole Kretschy

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

  2. Latent TB infection and pulmonary TB disease among patients with diabetes mellitus in Bandung, Indonesia.

    Science.gov (United States)

    Koesoemadinata, Raspati C; McAllister, Susan M; Soetedjo, Nanny N M; Febni Ratnaningsih, Dwi; Ruslami, Rovina; Kerry, Sarah; Verrall, Ayesha J; Apriani, Lika; van Crevel, Reinout; Alisjahbana, Bachti; Hill, Philip C

    2017-02-01

    Screening and treatment of latent TB infection (LTBI) and TB disease could reduce diabetes mellitus (DM)-associated TB. We aimed to describe the prevalence of LTBI and pulmonary TB among patients with DM in a TB-endemic setting. Patients with DM attending a hospital and community centres in Bandung, Indonesia, underwent LTBI screening using interferon gamma release assay (IGRA). TB was investigated by sputum smear, culture and x-ray. TB contacts from a parallel study were age- and sex-matched to patients with DM to compare LTBI and TB disease prevalence. Of 682 patients with DM screened, 651 (95.5%) were eligible. Among 'TB disease-free' patients, LTBI prevalence was 38.9% (206/530; 95% CI 34.7-43.2). Patients with DM were less likely to be IGRA positive than TB contacts (38.6%, 54/140; 95% CI 30.5-46.6 vs 68.6%, 96/140; 95% CI 60.9-72.3: pTB disease. Further studies should explore possible benefits of LTBI screening and preventive therapy in patients with DM in TB-endemic settings.

  3. Emission Characteristics of PVK Doped TbY(o-MBA)6(phen)2 Systems

    Institute of Scientific and Technical Information of China (English)

    Zhang Yuanyuan; Deng Zhenbo; Liang Chunjun; Chen Baomei; Xiao Jing; Xu Denghui; Wang Ruifen

    2006-01-01

    A rare earth complex TbY (o-MBA)6(phen)2 was synthesized, which was first used as an emitting material in electroluminescence.By doping it into the conjugated polymer PVK, single-layer and double-layer devices were fabricated with structures: device A: ITO/PVK: TbY (o-MBA)6(phen)2/LiF/Al;B: ITO/PVK: TbY (o-MBA)6(phen)2/AlQ/LiF/Al;C: ITO/PVK: TbY (o-MBA)6(phen)2/BCP/AlQ/LiF/Al.The characteristics of these devices were investigated.For single-layer and double-layer devices, the emission of PVK was completely restrained, and only the green emission from Tb3+ was observed in electroluminescence.The above mentioned observation is attributed to the different mechanism of electroluminescence and photoluminescence.In photoluminescence process, the energy of Tb complex may come from PVK through Frster energy transfer process, while in electroluminescence process direct sequential charge trapping appeares to be the main operating mechanism.From the optimized device B, brightly green emission can be obtained, and the highest EL brightness of the device reaches 213 cd·m-2 at 14 V.

  4. Excitation and emission processes of Tb{sup 3+} in porous anodic alumina

    Energy Technology Data Exchange (ETDEWEB)

    Dabboussi, S. [Unite de recherche de Spectroscopie Raman, Departement de Physique, Faculte des Sciences de Tunis, Elmanr 2092, Tunis (Tunisia); Elhouichet, H. [Unite de recherche de Spectroscopie Raman, Departement de Physique, Faculte des Sciences de Tunis, Elmanr 2092, Tunis (Tunisia)], E-mail: habib.elhouichet@fst.rnu.tn; Bouzidi, C. [Unite de recherche de Spectroscopie Raman, Departement de Physique, Faculte des Sciences de Tunis, Elmanr 2092, Tunis (Tunisia); Maliarevich, G.K.; Gaponenko, N.V. [Belarusian State University of Informatics and Radioelectronics, P. Browki St. 6, 220013 Minsk (Belarus); Oueslati, M. [Unite de recherche de Spectroscopie Raman, Departement de Physique, Faculte des Sciences de Tunis, Elmanr 2092, Tunis (Tunisia)

    2009-01-15

    The strong photoluminescence (PL) of porous anodic alumina (PAA) with terbium deposition is reported. PAA, which has a regular pore morphology, is considered an effective template for fabricating luminescent composites. Tb was deposited onto PAA films by immersion in alcoholic solution with terbium chloride followed by heat treatment. The PL spectra demonstrate typical bands of Tb{sup 3+} corresponding to {sup 5}D{sub 4} {yields} {sup 7}F{sub j} (j = 3, 4, 5, 6,) electron transition, with the maximum at 18,360 cm{sup -1} ({sup 5}D{sub 4} {yields} {sup 7}F{sub 5}). The PL mechanism of Tb{sup 3+} was systematically studied with annealing temperature. The non-radiative relaxation channel is provided by OH hydroxyls at the surface of porous anodic alumina and, after annealing at 900 deg. C, the PL yield is highly improved. The PL intensity of Tb{sup 3+} increases with laser power and a saturation phenomenon, associated with the ratio of Tb{sup 3+} to Tb{sup 4+} ions, is observed at approximately 90 W/cm{sup 2}. Based on a theoretical model, the optical cross-section {sigma} of terbium in PAA is estimated, with a value close to that of other porous materials doped with the rare-earth elements.

  5. Analysis of trace rare earth elements in misch metal by means of ITP-PIXE (isotachophoresis - Particle Induced X-ray Emission) method

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jian-Ying; Hirokawa, Takeshi; Nishiyama, Fumitaka; Kimura, Goji; Kiso, Yoshiyuki; Ito, Kazuaki; Shoto, Eiji [Hiroshima Univ., Higashi-Hiroshima (Japan). Faculty of Engineering

    1993-12-31

    A misch metal, an alloy of light rare earth elements, was analyzed by a new coupled analytical method, ITP-PIXE (isotachophoresis - Particle Induced X-ray Emission): The sample solution containing ca.1 mg misch metal was separated and fractionated by the use of a preparative isotachophoretic analyzer. The dropwise fractions containing nanomole rare earth elements were analyzed off-line by PIXE. The matrix effect in X-ray measurement was reduced by the isotachophoretic removing of the dominant lanthanoids and preconcentration of the trace elements of interest. Consequently the minor elements, Sm, Gd, Tb, Dy, Ho, Er, Yb and Y could be determined accurately. The most trace element found was Yb (4ppm, 4ng in 1mg sample). The good accuracy of ITP-PIXE method was also demonstrated for several model samples of lanthanoids, where La was the dominant element and the thirteen lanthanoids were the minor elements. The ratio was varied from 500:1 to 50000:1. Even in the case of 50000:1, ca.10% accuracy was achieved for each minor element except for Sm(23%), Gd(17%) and Yb(18%). The analytical results by ITP-PIXE were compared with those by means of ICP-AES (Inductively Coupled Plasma - Atomic Emission Spectrometry). (author).

  6. Magnetic Rare-Earth Superlattices

    DEFF Research Database (Denmark)

    Majkrzak, C.F.; Gibbs, D.; Böni, P.

    1988-01-01

    The magnetic structures of several single‐crystal, magnetic rare‐earth superlattice systems grown by molecular‐beam epitaxy are reviewed. In particular, the results of recent neutron diffraction investigations of long‐range magnetic order in Gd‐Y, Dy‐Y, Gd‐Dy, and Ho‐Y periodic superlattices...... are presented. In the Gd‐Y system, an antiphase domain structure develops for certain Y layer spacings, whereas modified helical moment configurations are found to occur in the other systems, some of which are commensurate with the chemical superlattice wavelength. References are made to theoretical interaction...

  7. Stop TB in My Lifetime: A Call for a World Free of TB - World TB Day 2013

    Centers for Disease Control (CDC) Podcasts

    2012-03-12

    In this podcast Dr. Kenneth Castro, Director of the Division of Tuberculosis Elimination, discusses World TB Day, the 2013 slogan and theme.  Created: 3/12/2012 by National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (NCHHSTP).   Date Released: 3/13/2012.

  8. Air separation and oxygen storage properties of hexagonal rare-earth manganites

    Science.gov (United States)

    Abughayada, Castro

    This dissertation presents evaluation results of hexagonal Y1-x RxMnO3+delta (R = Er, Y, Dy, Pr, La, Tb and Ho) rare-earth manganites for prospective air separation applications. In these materials, oxygen content is sensitively dependent on the surrounding conditions of temperature and/or oxygen partial pressure, and therefore they exhibit the ability to selectively absorb, store, and release significant amounts of separated oxygen from air. This study presents a full characterization of their thermogravimetric characteristics and air separation capabilities. With the expected potential impact of oxygen content on the physical properties of these materials, the scope of this work is expanded to explore other relevant properties such as magnetic, transport, and dilatometric characteristics. Single-phase polycrystalline samples of these materials were achieved in the hexagonal P63cm phase through solid state reaction at elevated temperatures. Further annealings under reducing conditions were required for samples with large rare-earth cations in order to suppress the competing perovskite structure and form in the anticipated hexagonal phase. Thermogravimetric measurements in oxygen atmospheres demonstrated that samples with the larger R ionic radii show rapid and reversible incorporation of significant amounts of excess oxygen (0.41 > delta > 0) at an unusual low temperature range ~190-325 °C. The reversible oxygen storage characteristics of HoMnO3+delta and related materials shown by the fast incorporation and release of interstitial oxygen at easily accessible elevated temperatures of ~300 °C demonstrate the feasibility and potential for low-cost thermal swing adsorption TSA process for oxygen separation and enrichment from air. Neutron and X-ray powder diffraction measurements confirmed the presence of three line compounds RMnO3+delta, the oxygen stoichiometric P6 3cm (delta = 0 for all R), the intermediate oxygen content superstructure phase R3c (delta ~ 0

  9. Sensitization and Intra-molecular Energy Transfer of Eu3+ by Tb3+ in Eu-Tb Binuclear Complexes/PMMA

    Institute of Scientific and Technical Information of China (English)

    HAN Jing; LI Jie

    2011-01-01

    A series of Eu0.5Tb0.5(TTA)3Phen/PMMA (TTA=thenoyltrifluoroacetone, Phen=phenanthroline)and Eu0.5Tb0.5(TTA)3Dipy/PMMA (Dipy=2,2'-dipyridyl) were prepared by in-situ polymerization. The structures of the composites were characterized by IR spectra and electron spectrum. Photoluminescence properties were investigated by UV-Vis spectra and fluorescence spectra. Meanwhile, the energy transfer models were set up.The results indicated that polymer parts were attached with the rare-earth molecular parts in the composite luminescent materials. Eu0.5Tb0.5(TTA)3Phen/PMMA and Eu0.5Tb0.5(TTA)3Dipy/PMMA emitted mostly characteristic fluorescence of europium ion and intense red fluorescence with peak wavelength at 611.8 nm and bandwidth of 10.4 nm under UV excitation at 365 nm. Fluorescence intensity of Eu0.5Tb0.5(TTA)3Phen/PMMA was found to be influenced with the content of MMA. The fluorescence emission of europium ions was greatly sensitized by terbium ions and the enhancement of red emission was most likely due to the energy transfer enhancement from Th3+ to Eu3+.

  10. TB in Correctional Facilities Is a Public Health Concern

    Science.gov (United States)

    ... this? Submit Button Past Emails CDC Features TB in Correctional Facilities is a Public Health Concern Recommend ... health concern. Figure 1 (larger view). TB Control in Correctional Facilities Diagnosing and treating TB in correctional ...

  11. Lanthanide dinuclear complexes constructed from mixed oxygen-donor ligands: the effect of substituent positions of the neutral ligand on the magnetic dynamics in Dy analogues.

    Science.gov (United States)

    Zhu, Wen-Hua; Li, Shan; Gao, Chen; Xiong, Xia; Zhang, Yan; Liu, Li; Powell, Annie K; Gao, Song

    2016-03-21

    Two series of lanthanide dinuclear complexes with the general formulae, [Ln(n-PNO)(Bza)3(H2O)] {Bza = benzoic acid; n = 3, n-PNO = 3-picoline N-oxide, Dy(1) and Er(2); and n = 4, n-PNO = 4-picoline N-oxide, Nd(3), Eu(4), Gd(5), Tb(6), Dy(7), Er(8) and Y(9)} have been successfully synthesized by the hydrothermal method. Single-crystal X-ray diffraction experiments illustrate that the two series of compounds possess similar carboxylic ligand-bridged dinuclear structure and coordination geometry around the lanthanide ions despite the different methyl-substituent positions on the neutral ligand. Comparative studies of the Dy analogues in the static-field measurements reveal only a little difference with a small butterfly-shaped opening for complex 1 and a close hysteresis loop for 7 at 2.0 K. However, systematic investigations of the alternating-current (ac) measurements indicate that the different substituent positions of the picoline N-oxide ligand have a significant effect on the magnetic relaxation dynamics. A more substantial suppression of the quantum tunnelling of magnetization (QTM) effect and pronounced slow magnetic relaxation were observed in complex 7 as compared to 1 under both zero and a 1 kOe static field.

  12. Diagnosis of active TB using aptamers

    CSIR Research Space (South Africa)

    Khati, M

    2013-08-01

    Full Text Available ) and the 6-kDa early secreted antigen target (ESAT-6), which are potent T-cell antigens that are recognised by over 70% of TB patients. We then used these aptamers to develop a TB diagnostic tool that can be used at point-of-care for early and rapid detection...

  13. TB Testing for People Living with HIV

    Centers for Disease Control (CDC) Podcasts

    2012-07-23

    Dr. Kenneth Castro, Director of the Division of Tuberculosis Elimination, explains why it is important for people living with HIV to be tested for TB.  Created: 7/23/2012 by National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (NCHHSTP).   Date Released: 7/23/2012.

  14. Magnetic properties of ball-milled TbFe2 and TbFe2B

    Indian Academy of Sciences (India)

    J Arout Chelvane; S Kasiviswanathan; M V Rao; G Markandeyulu

    2004-04-01

    The magnetic properties of ball-milled TbFe2 and TbFe2B were studied by magnetization measurements. X-ray diffraction studies on TbFe2B showed that boron occupied interstitial position in the crystal structure, just as hydrogen did. The value of the saturation magnetization of TbFe2B was found to be smaller than that of TbFe2. This is explained on the basis of a charge transfer between the boron atoms and the 3d band of Fe. The anisotropy of TbFe2B was found to be large compared to that of TbFe2. X-ray diffractograms for the ball milled samples showed that after 80 h of milling, a predominantly amorphous phase was obtained. TbFe2B was found to undergo easy amorphization compared to TbFe2. Magnetization of TbFe2 was found to decrease rapidly with initial milling hours and was found to be constant with further hours of milling. TbFe2B exhibited an anomalous behaviour with an increase in moment with milling hours and this may be due to the segregation of -Fe.

  15. 'Z(S)-MDR-TB' versus 'Z(R)-MDR-TB': improving treatment of MDR-TB by identifying pyrazinamide susceptibility.

    Science.gov (United States)

    Zhang, Ying; Chiu Chang, Kwok; Leung, Chi-Chiu; Wai Yew, Wing; Gicquel, Brigitte; Fallows, Dorothy; Kaplan, Gilla; Chaisson, Richard E; Zhang, Wenhong

    2012-07-01

    Indispensable for shortening treatment of drug-susceptible tuberculosis (TB), pyrazinamide (PZA, Z) is also essential in the treatment of multidrug-resistant (MDR)-TB. While resistance to PZA in MDR-TB is associated with poor treatment outcome, bacillary susceptibility to PZA along with the use of fluoroquinolone (FQ) and second-line injectable drugs (SLIDs) may predict improved treatment success in MDR-TB. Despite a high prevalence of PZA resistance among MDR-TB patients (10%-85%), PZA susceptibility testing is seldom performed because of technical challenges. To improve treatment of MDR-TB, we propose to: (i) classify MDR-TB into PZA-susceptible MDR-TB (Z(S)-MDR-TB) and PZA-resistant MDR-TB (Z(R)-MDR-TB); (ii) use molecular tests such as DNA sequencing (pncA, gyrA, rrs, etc.) to rapidly identify Z(S)-MDR-TB versus Z(R)-MDR-TB and susceptibility profile for FQ and SLID; (iii) refrain from using PZA in Z(R)-MDR-TB; and (iv) explore the feasibility of shortening the treatment duration of Z(S)-MDR-TB with a regimen comprising PZA plus at least two bactericidal agents especially new agents like TMC207 or PA-824 or delamanid which the bacilli are susceptible to, with one or two other agents. These measures may potentially shorten therapy, save costs, and reduce side effects of MDR-TB treatment.

  16. Isomer Spectoscopy of Neutron-Rich {sup 168}Tb{sub 103}

    Energy Technology Data Exchange (ETDEWEB)

    Gurgi, L. A.; Regan, P. H.; Soderstrom, P. -A.; Watanabe, H.; Walker, P. M.; Podolyak, Zs.; Nishimura, S.; Berry, T. A.; Doornenbal, P.; Lorusso, G.; Kondev, F. G.

    2017-11-01

    In-flight fission of a 345 MeV per nucleon 238U primary beam on a 2 mm thick 9Be target has been used to produce and study the decays of a range of neutron-rich nuclei centred around the doubly mid-shell nucleus 170Dy at the RIBF Facility, RIKEN, Japan. The produced secondary fragments of interest were identified event-by-event using the BigRIPS separator. The fragments were implanted into the WAS3ABI position sensitive silicon active stopper which allowed pixelated correlations between implants and their subsequent β-decay. Discrete γ-ray transitions emitted following decays from either metastable states or excited states populated following beta decay were identified using the 84 coaxial high-purity germanium (HPGe) detectors of the EURICA spectrometer, which was complemented by 18 additional cerium-doped lanthanum bromide (LaBr3) fast-timing scintillation detectors from the FATIMA collaboration. This paper presents the internal decay of a metastable isomeric excited state in the odd-odd nucleus 168Tb, which corresponds to a single proton-neutron hole configuration in the valence maximum nucleus 170Dy. These data represent the first information on excited states in this nucleus, which is the most neutron-rich odd-odd isotope of terbium (Z=65) studied to date. Nilsson configurations associated with an axially symmetric, prolate-deformed nucleus are proposed for the 168Tb ground state the observed isomeric state by comparison with Blocked BCS-Nilsson calculations.

  17. Understanding social context on TB cases

    Science.gov (United States)

    Ariyanto, Y.; Wati, D. M.

    2017-01-01

    Tuberculosis (TB) nowadays still becomes one of the world’s deadliest communicable disease. More than half were in South-East Asia and Western Pacific Regions, including Indonesia. As developing country, Indonesia remains classic problems in overcoming TB, that is discontinuation on treatment. Most of discontinuation on treatment among TB patients are affected by diagnostic delay that caused by patient delay. These phenomena occur in many areas, rural to suburb, coastal to plantation, and so on, and they are related with social context among community that could be social capital for each community to deal with TB. Jember as one of county in East Java is known as plantation area. It also has a high prevalence of TB. This study focused on understanding about social context among community, especially on plantation area. This cross-sectional study involved in three districts of Jember, those are Tanggul, Pakusari, and Kalisat. The data were obtained directly from the TB patients, local community, and Primary Health Care (PHC) where the patients recorded. Spatial analysis and social network analysis (SNA) were applied to obtain health seeking behavior pattern among the TB patients coincide the community. Most of TB patients had already chosen health professionals to lead the treatment, although some of them remained to choose self-medication. Meanwhile, SNA showed that religious leader was considered as main part of countermeasures of TB. But they didn’t ever become central figures. So it can be concluded that there are other parts among community who can contribute due to combatting on TB.

  18. Structural and Ferroic Properties of La, Nd, and Dy Doped BiFeO3 Ceramics

    Directory of Open Access Journals (Sweden)

    Ashwini Kumar

    2015-01-01

    Full Text Available Polycrystalline samples of Bi0.8RE0.2FeO3 (RE = La, Nd, and Dy have been synthesized by solid-state reaction route. X-ray diffraction (XRD patterns of Bi0.8La0.2FeO3 and Bi0.8Nd0.2FeO3 were indexed in rhombohedral (R3c and triclinic (P1 structure, respectively. Rietveld refined XRD pattern of Bi0.8Dy0.2FeO3 confirms the biphasic (Pnma + R3c space groups nature. Raman spectroscopy reveals the change in BiFeO3 mode positions and supplements structural change with RE ion substitution. Ferroelectric and ferromagnetic loops have been observed in the Bi0.8RE0.2FeO3 ceramics at room temperature, indicating that ferroelectric and ferromagnetic ordering coexist in the ceramics at room temperature. The magnetic measurements at room temperature indicate that rare-earth substitution induces ferromagnetism and discerns large and nonzero remnant magnetization as compared to pristine BiFeO3.

  19. Enhanced collectivity of gamma vibration in neutron-rich Dy isotopes with N=108 - 110

    CERN Document Server

    Yoshida, Kenichi

    2016-01-01

    Background: The $\\gamma$ vibrational mode of excitation is an acknowledged collective mode in deformed nuclei. The collectivity depends on the details of the shell structure around the Fermi levels, in particular the presence of the orbitals that have the enhanced transition matrix elements of the non-axial quadrupole excitation. Quite recently, a sudden decrease in the excitation energy of the $\\gamma$ vibration was observed at RIKEN RIBF for the neutron-rich Dy isotopes at $N=106$. Purpose: In the present work, by studying systematically the microscopic structure of the $\\gamma$ vibration in the neutron-rich Dy isotopes with $N=98-114$, we try to understand the mechanism of the observed softening. Methods: The low-frequency modes of excitation in the neutron-rich rare-earth nuclei are described based on nuclear density-functional theory. We employ the Skyrme energy-density functionals (EDF) in the Hartree-Fock-Bogoliubov calculation for the ground states and in the Quasiparticle Random-Phase Approximation (...

  20. Preparation of Rare-Earth Composite Ferrite Magnetic Fluid

    Institute of Scientific and Technical Information of China (English)

    蒋荣立; 刘永超; 刘守坤; 鞠明礼

    2004-01-01

    Water-based rare-earth ferrite (RexFe3-xO4)magnetic fluids were prepared by chemical co-precipitation method. The result shows that saturation magnetic intensity of ferrite magnetic fluids can be improved by adding Dy3+ and the saturation magnetic intensity will reach the highest if n(Fe)∶n(Dy3+)=30∶1. The modification and formation mechanism of RexFe3-xO4 particles is discussed in detail. The physicochemical properties are investigated by the Gouy magnetic balance, IR, TEM, XRD, and EDX, etc.

  1. Photoluminescence and thermoluminescence properties of Dy{sup 3+}/Eu{sup 2+} activated Na{sub 21}Mg(SO{sub 4}){sub 10}Cl{sub 3} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Kore, Bhushan P. [Department of Physics, RTM Nagpur University, Nagpur 440033 (India); Dhoble, N.S. [Department of Chemistry, Sevadal Mahila Mahavidyalaya, Nagpur 440009 (India); Park, K. [Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 143-747 (Korea, Republic of); Dhoble, S.J., E-mail: sjdhoble@rediffmail.com [Department of Physics, RTM Nagpur University, Nagpur 440033 (India)

    2013-11-15

    In the present work luminescence properties of rare earth (RE) doped Na{sub 21}Mg(SO{sub 4}){sub 10}Cl{sub 3} were studied. Modified solid state method was employed to synthesize the phosphors. The influence of RE (RE=Dy and Eu) doping on the luminescence properties of as prepared phosphor were investigated in detail. PL emission spectra of the Na{sub 21}Mg(SO{sub 4}){sub 10}Cl{sub 3}:Dy phosphor exhibits the characteristic emission of Dy. The characteristic Dy{sup 3+} emission in the form of peaks around 482 and 576 nm corresponding to transitions {sup 4}F{sub 9/2}→{sup 6}H{sub 15/2} and {sup 4}F{sub 9/2}→{sup 6}H{sub 13/2} was seen when excited by excitation wavelength 351 nm. However, interesting thermoluminescence results are observed in case of Dy as well as Eu doped Na{sub 21}Mg(SO{sub 4}){sub 10}Cl{sub 3}. The TL glow curves for Na{sub 21}Mg(SO{sub 4}){sub 10}Cl{sub 3}:Dy exhibit broad peak composed of three overlapping peaks, these peaks were deconvoluted using deconvolution program. The peaks at different temperatures indicate that different sets of traps are being activated within the particular temperature range each with its own value of activation energy (E) and frequency factor (s). The peaks observed were due to formation of trap levels by γ-rays irradiation and subsequently activation of traps on thermal stimulation. The trapping parameters for both the samples were calculated using Chen's peak shape method and reported in this paper. -- Highlights: • RE doped Na{sub 21}Mg(SO{sub 4}){sub 10}Cl{sub 3} (RE=Dy,Eu) prepared by modified solid state method. • The XRD-pattern of the as prepared phosphor powder shows a good agreement with standard JCPDS file no.00-041-1473. • PL characteristics show the emission of Dy and Eu ions. • In comparison to CaSO{sub 4}:Dy dosimetric peak Na{sub 21}Mg(SO{sub 4}){sub 10}Cl{sub 3}:Dy material is found to be 1.23 times more sensitive. • Linear response of γ-rays in the dose range 100 mGy–1 Gy.

  2. Chemically Inhomogeneous RE-Fe-B Permanent Magnets with High Figure of Merit: Solution to Global Rare Earth Criticality.

    Science.gov (United States)

    Jin, Jiaying; Ma, Tianyu; Zhang, Yujing; Bai, Guohua; Yan, Mi

    2016-08-24

    The global rare earth (RE) criticality, especially for those closely-relied Nd/Pr/Dy/Tb in the 2:14:1-typed permanent magnets (PMs), has triggered tremendous attempts to develop new alternatives. Prospective candidates La/Ce with high abundance, however, cannot provide an equivalent performance due to inferior magnetic properties of (La/Ce)2Fe14B to Nd2Fe14B. Here we report high figure-of-merit La/Ce-rich RE-Fe-B PMs, where La/Ce are inhomogeneously distributed among the 2:14:1 phase. The resultant exchange coupling within an individual grain and magnetostatic interactions across grains ensure much superior performance to the La/Ce homogeneously distributed magnet. Maximum energy product (BH)max of 42.2 MGOe is achieved even with 36 wt. % La-Ce incorporation. The cost performance, (BH)max/cost, has been raised by 27.1% compared to a 48.9 MGOe La/Ce-free commercial magnet. The construction of chemical heterogeneity offers recipes to develop commercial-grade PMs using the less risky La/Ce, and also provides a promising solution to the REs availability constraints.

  3. First-principles prediction of the magnetism of 4f rare-earth-metal-doped wurtzite zinc oxide

    Institute of Scientific and Technical Information of China (English)

    AG El Hachimi; H Zaari; A Benyoussef; M El Yadari; A El Kenz

    2014-01-01

    Electronic structure and magnetic properties of wurtzite ZnO semiconductor doped with rare earth (RE=La, Ce, Pr, Pm, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb) atoms were studied using spin-polarized density functional theory based on the full-potential linear augmented plane wave (FP-LAPW) method as implemented in the Wien2k code. In this approach the generalized gradient ap-proximation (GGA) was used for the exchange-correlation (XC) potential. Our results showed that the substitution of RE ions in ZnO induced spins polarized localized states in the band gap. Moreover, the studied DMSs compounds retained half metallicity at dopant concentration x=0.625%for most of the studied elements, with 100%spin polarization at the Fermi level (EF). The total magnetic moments of these compounds existed due to RE 4f states present at EF, while small induced magnetic moments existed on other non-magnetic atoms as well. Finally, the energy difference between far and near configurations was investigated. It was found that the room temperature ferromagnetism was possible for RE-doped ZnO at near configuration. Since the RE-RE separation was long enough (far configuration) for magnetic coupling, the system became paramagnetic or antiferromagnetic ground state.

  4. Chemically Inhomogeneous RE-Fe-B Permanent Magnets with High Figure of Merit: Solution to Global Rare Earth Criticality

    Science.gov (United States)

    Jin, Jiaying; Ma, Tianyu; Zhang, Yujing; Bai, Guohua; Yan, Mi

    2016-08-01

    The global rare earth (RE) criticality, especially for those closely-relied Nd/Pr/Dy/Tb in the 2:14:1-typed permanent magnets (PMs), has triggered tremendous attempts to develop new alternatives. Prospective candidates La/Ce with high abundance, however, cannot provide an equivalent performance due to inferior magnetic properties of (La/Ce)2Fe14B to Nd2Fe14B. Here we report high figure-of-merit La/Ce-rich RE-Fe-B PMs, where La/Ce are inhomogeneously distributed among the 2:14:1 phase. The resultant exchange coupling within an individual grain and magnetostatic interactions across grains ensure much superior performance to the La/Ce homogeneously distributed magnet. Maximum energy product (BH)max of 42.2 MGOe is achieved even with 36 wt. % La-Ce incorporation. The cost performance, (BH)max/cost, has been raised by 27.1% compared to a 48.9 MGOe La/Ce-free commercial magnet. The construction of chemical heterogeneity offers recipes to develop commercial-grade PMs using the less risky La/Ce, and also provides a promising solution to the REs availability constraints.

  5. Rare earth elements in street dust and associated health risk in a municipal industrial base of central China.

    Science.gov (United States)

    Sun, Guangyi; Li, Zhonggen; Liu, Ting; Chen, Ji; Wu, Tingting; Feng, Xinbin

    2017-05-26

    The content levels, distribution characteristics, and health risks associated with 15 rare earth elements (REEs) in urban street dust from an industrial city, Zhuzhou, in central China were investigated. The total REE content (∑REE) ranged from 66.1 to 237.4 mg kg(-1), with an average of 115.9 mg kg(-1), which is lower than that of Chinese background soil and Yangtze river sediment. Average content of the individual REE in street dust decreased in the order Ce > La > Nd > Y > Pr > Sm > Gd > Dy > Er > Yb > Eu > Ho > Tb > Tm > Lu. The chondrite-normalized REE pattern indicated light REE (LREE) enrichment, a relatively steep LREE trend, heavy REE (HREE) depletion, a flat HREE trend, a Eu-negative anomaly and a Ce-positive anomaly. Foremost heavy local soil and to less degree anthropogenic pollution are the main sources of REE present in street dust. Health risk associated with the exposure of REE in street dust was assessed based on the carcinogenic and non-carcinogenic effect and lifetime average daily dose. The obtained cancer and non-cancer risk values prompt for no augmented health hazard. However, children had greater health risks than that of adults.

  6. Distribution of rare earths, thorium and uranium in bryophytes and soils in Tripui Ecological Station, Minas Gerais, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Palmieri, Helena E.L. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)], E-mail: help@cdtn.br; Nalini Junior, Herminio A. [Universidade Federal de Ouro Preto (UFOP), MG (Brazil). Dept. de Geologia], E-mail: nalini@degeo.ufop.br; Friese, Kurt [Helmholtz Centre for Environmental Research- UFZ, Magdeburg (Germany). Dept. of Lake Research], E-mail: kurt.friese@ufz.de

    2007-07-01

    The concentrations of rare earth elements (REEs), thorium and uranium were determined in liverworts (Noteroclada confluens (Tayl.) and Dumortirea hirsute (Sw.) Nees), in mosses (Leucobryum martianum (Hornsh.) Hampe, Vesicularia vesicularis (Schwaegr.) Broth., Pyrrhobruym spiniforme (Hedw.) Mitt. and Sematophyllum subsimplex (Hedw.) Mitt.) and in the soil upon which they were growing. The samples were collected on the margins of the main streams of the Tripui Ecological Station, located in the valley of the Tripui stream near the town of Ouro Preto, Minas Gerais State, Brazil. For decades, this Station has been the object of interest of many studies due to its historical, ecological and environmental importance. Analyses in bryophytes (mosses and liverworts) were determined by inductively coupled plasma mass spectrometry (ICP-MS) and in the soil samples by using neutron activation analysis (NAA), specifically the k{sub 0}-standardization method and the energy dispersive spectrometry technique (EDS). Lanthanum (La), cerium (Ce) and neodymium (Nd) were present in higher concentrations in soils and bryophytes than other REEs. It was observed that in all the collected bryophytes species the elements Th, U, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er and Yb were transferred from the soil water to these plants. These bryophytes presented different capacities of accumulating these elements with the liverworts (Noteroclada confluens and Dumortirea hirsute) and the moss Leucobryum martianum showing a more efficient accumulation capacity than the other bryophyte species. (author)

  7. Crystal Structures of Dy2(WO4)3 and GdY(WO4)3

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Two compounds, Dy2(WO4)3 and GdY(WO4)3; were synthesized by using the standard solid state reaction tech-nique. The crystal structure was determined by powder X-ray diffraction and Rietveld refinement method. It is found thatboth compounds have Eu2(WO4)3-type monoclinic structure, with space group C 2/c, Z = 4. The unit cell parameters ofDy2(WO4)3 are a = 0.75981(1) nm, b = 1.13220(1) nm, c = 1.13254(1) nm, and β= 109.8001(3)°, and those of GdY(WO4)3are a = 0.76175(1) nm, b = 1.13543(1) nm, c = 1.13496(2) nm, and β= 109.8015(13)°. Each W atom has four oxygen near-est neighbors, while each rare-earth atom is surrounded by eight oxygen atoms. WO4 tetrahedra share their four verticeswith REO8 (RE = Dy, Gd, or Y) trigondodecahedra and some REO8 trigondodecahedra share an edge with each other. Thephase transition and the magnetic properties were investigated by differential thermal analysis (DTA) and dc superconduct-ing quantum interference device (SQUID) magnetometer.

  8. Synthesis and photoluminescence properties of microcrystalline Sr{sub 2}ZnWO{sub 6}:RE{sup 3+} (RE = Eu, Dy, Sm and Pr) phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Dabre, K.V. [Department of Physics, Arts, Commerce and Science College, Koradi, Nagpur 441111 (India); Park, K. [Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 143-747 (Korea, Republic of); Dhoble, S.J., E-mail: sjdhoble@rediffmail.com [Department of Physics, R.T.M. Nagpur University, Nagpur 440033 (India)

    2014-12-25

    Graphical abstract: CIE chromaticity coordinate diagram (1931) indicating different colors of Sr{sub 2}ZnWO{sub 6}:RE{sup 3+} (RE = Eu (a), Dy (b and c), Sm (d–f) and Pr (g and h)) phosphor under different excitation 466 nm (a), 312 nm (b), 454 nm (c), 313 nm (d), 408 nm (e), 482 nm (f), 315 nm (g) and 450 nm (h). - Highlights: • Microcrystalline Sr{sub 2}ZnWO{sub 6}:RE{sup 3+} (RE = Eu, Dy, Sm and Pr) phosphors were synthesized by solid state method. • Photoluminescence properties of phosphor were investigated. • Color of the phosphor for different excitation has been verified by chromaticity diagram. • The host absorption and energy transfer were investigated. - Abstract: The novel microcrystalline Sr{sub 2}ZnWO{sub 6}:RE{sup 3+} (RE = Eu, Dy, Sm and Pr) phosphors were synthesized by solid-state reaction method at 1250 °C and their photoluminescence properties were investigated. The Eu{sup 3+} and Dy{sup 3+} activated phosphors show intense red (616 nm) and yellow (574 nm) emission respectively; which indicate that the rare earth ions are substituted at non-centrosymmetric site in the host lattice. Near white (Dy{sup 3+}) and reddish-orange (Sm{sup 3+}) emissions of rare earth ions in the host lattice show strong host absorption and energy transfer from the host to activator ion. Pr{sup 3+} activated phosphor shows a series of emission peaks in the visible region with the most intense peak in the blue region at 491 and 499 nm.

  9. Multidrug and extensively drug-resistant TB (M/XDR-TB): problems and solutions.

    Science.gov (United States)

    Prasad, Rajendra

    2010-10-01

    Multi Drug Resistant Tuberculosis (MDR-TB) and Extensively Drug Resistant Tuberculosis (XDR-TB) are posing a threat to the control of tuberculosis. The first WHO-IUATLD antituberculosis drug resistance surveillance carried out in 1994 in 35 countries reported the median prevalence of primary and acquired multi drug resistance as 1.4% and 13% respectively. Subsequently, second, third and fourth WHO-IUATLD global drug resistance surveillances were carried out in 1996-99, 1999-2002 and 2002-2007 respectively. Based on drug resistance information from 114 countries, the proportion of MDR-TB among all cases was estimated for countries with no survey information. It was estimated that 4,89,139 cases of MDR-TB emerged in 2006. China and India carry approximately 50% of the global burden. 35 countries and two Special Administrative Regions (SARs) reported data on XDR-TB for the first time in 2006. Multidrug and extensively drug-resistant TB 2010 Global report on Surveillance and response estimated that 4,40,000 cases of MDR-TB emerged globally in 2008 and caused an estimated 1,50,000 deaths. 5.4% of MDR-TB cases were found to have XDR-TB. To date, a cumulative total of 58 countries have confirmed at least one case of XDR-TB. M/XDR-TB is a man-made problem and its emergence can be prevented by prompt diagnosis and effective use of first line drugs in every new patient. The DOTS Plus proposed by WHO highlights the comprehensive management strategy to control MDR-TB. Laboratory services for adequate and timely diagnosis of M/XDR-TB must be strengthened and programmatic management of M/XDR-TB must be scaled up as per target set by global plan. Proper use of second-line drugs must be ensured to cure existing MDR-TB, to reduce its transmission and to prevent XDR-TB. Sound infection control measures to avoid further transmission of M/XDR-TB and research towards development of new diagnostics, drugs and vaccines should be promoted to control M/XDR-TB.

  10. Isothermal section of Dy-Zr-Si ternary system at 773 K

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The isothermal section of the phase diagram of the Dy-Zr-Si ternary system at 773 K was determined by X-ray diffraction (XRD) analysis, metallographic analysis, and scanning electron microscopy (SEM) with energy-dispersive spectrometer (EDS) analysis. The isothermal section consists of 13 single-phase regions, 23 two-phase regions, and 11 three-phase regions. The solubilities of Zr in Dy, Dy5Si4, Dy5Si3, DySi, DySi2, DySi1.67, and Dy in Zr, Zr2Si, Zr3Si2, Zr5Si4, ZrSi, and ZrSi2 were determined at 773 K.

  11. Confronting TB/HIV in the era of increasing anti-TB drug resistance

    Directory of Open Access Journals (Sweden)

    Chakaya Jeremiah

    2008-11-01

    Full Text Available Abstract HIV associated TB is a major public health problem. In 2006, it was estimated that there were over 700,000 people who suffered from HIV associated TB, of whom about 200, 000 have died. The burden of HIV associated TB is greatest in Sub-Saharan Africa where the TB epidemic is primarily driven by HIV. There has been steady progress made in reducing the burden of HIV in TB patients with an increasing number of TB patients tested for HIV and provided with cotrimoxazole preventive therapy (CPT and anti-retroviral treatment (ART. Less progress is being made to reduce the burden of TB in people living with HIV. The number of HIV infected persons reported to have been screened for TB was less than 1% while Isoniazid preventive therapy was reported to have been provided to less than 0.1% of eligible persons in 2006. A major push is urgently needed to accelerate the implementation of three important interventions. The three are Intensified TB Screening (ICF among people living with HIV, the provision of Isoniazid Preventive Therapy (IPT and TB Infection Control(IC. These interventions are best carried out by HIV control programmes which should therefore be encouraged to take greater responsibility in implementing these interventions.

  12. X-ray magnetic circular dichroism (XMCD) study of a methoxide-bridged DyIII-CrIII cluster obtained by fluoride abstraction from cis-[CrIIIF2(phen)2]+

    DEFF Research Database (Denmark)

    Dreiser, Jan; Pedersen, Kasper Steen; Birk, Torben

    2012-01-01

    An isostructural series of dinuclear chromium(III)-lanthanide(III) clusters is formed by fluoride abstraction of cis-[CrF(2)(phen)(2)](+) by Ln(3+) resulting in LnF(3) and methoxide-bridged Cr-Ln clusters (Ln = Nd (1), Tb (2), Dy (3)) of formula [Cr(III)(phen)(2)(µ-MeO)(2)Ln(NO(3))(4)]·xMeOH (x = 2...

  13. Energy transfer from Ce~(3+) to Tb~(3+) and Eu~(3+) in zinc phosphate glasses

    Institute of Scientific and Technical Information of China (English)

    马崇庚; 江莎; 周贤菊

    2010-01-01

    Ce3+,Eu3+ and Tb3+ singly doped and Ce3+/Eu3+ and Ce3+/Tb3+ co-doped zinc phosphate glasses were prepared by sintering P2O5,ZnO,Ce2(C2O4)3·10H2O and Eu2O3/Tb4O7 mixtures at 1200 °C in the air for 2 h and then annealing at 450 °C for 10 h.The obtained glasses were homogeneous and transparent.The glasses without Ce3+ were colorless and those with Ce3+ showed slightly yellow.The singly doped glasses showed strong emissions and excitations from doped trivalent rare earth ions.Strong energy transfer from Ce3+ to...

  14. An investigation of the hydrogen desorption from Nd{sub 2}Fe{sub 17}H{sub x} and Dy{sub 2}Fe{sub 17}H{sub x} compounds by differential scanning calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Cuevas, F. [ICMPE/CNRS-UPEC, UMR 7182, 2-8, rue Henri Dunant 94320, Thiais (France); Isnard, O., E-mail: olivier.isnard@grenoble.cnrs.fr [Institut Néel du CNRS et Université Joseph Fourier, BP 166 X, 38042 Grenoble cedex 9 (France); Villeroy, B. [ICMPE/CNRS-UPEC, UMR 7182, 2-8, rue Henri Dunant 94320, Thiais (France)

    2013-06-10

    Highlights: • We investigate the hydrogen desorption from R{sub 2}Fe{sub 17}H{sub x} (R = Nd and Dy) compounds. • The heat of hydrogen desorption is 29.2 ± 0.8 kJ mol H{sup −1} for both R{sub 2}Fe{sub 17}H{sub x} family compounds. • Hydrogen desorption activation energies have been determined from DSC. • Thermodynamical data are analysed for both heavy (Dy) and light (Nd) rare earth elements in the light of the precise knowledge of the crystal structure. - Abstract: Hydrogen desorption from R{sub 2}Fe{sub 17}H{sub x} (R = Nd and Dy) compounds with x ≤ 5 has been studied using differential scanning calorimetry (DSC). Overall hydrogen binding energies are very similar in both systems regardless their different crystal structures. The heat of hydrogen desorption is 29.2 ± 0.8 kJ mol H{sup −1} for both R{sub 2}Fe{sub 17}H{sub x} family compounds. Desorption activation energies are also very close: 78 ± 8 kJ and 79 ± 4 kJ mol H{sup −1} for Nd and Dy-containing compounds, respectively. The rare earth nature modifies however the local interaction between hydrogen and the intermetallic compound. For Nd, H-atoms occupy two non-equivalent and well-defined energy sites whereas a unique energy site with a broad energy distribution is detected for Dy. This peculiar behavior is discussed in terms of the different structural properties of the light (Nd) and heavy (Dy) rare-earth R{sub 2}Fe{sub 17} compounds.

  15. Thermodynamic Optimization of DyCl3 -NaCl System

    Institute of Scientific and Technical Information of China (English)

    叶信宇; 孙益民; 张静; 谈君君

    2005-01-01

    In this paper, the phase diagram of the DyCl3 -NaCl system is optimized and calculated with CALPHAD ( calculation of phase diagram ) technology. A set of thermodynamic functions of compounds Na3 DyCl6, NaDyCl4, and NaDY2 Cl7 have been optimized and calculated based on an interactive computer-assisted analysis. The optimized thermodynamic parameters, calculated phase diagram and experimental phase diagram are thermodynamically serf-consistent.

  16. Investigations of the effect of nonmagnetic Ca substitution for magnetic Dy on spin-freezing in Dy2Ti2O7

    Science.gov (United States)

    Anand, V. K.; Tennant, D. A.; Lake, B.

    2015-11-01

    Physical properties of partially Ca substituted hole-doped Dy2Ti2O7 have been investigated by ac magnetic susceptibility {χ\\text{ac}}(T) , dc magnetic susceptibility χ (T) , isothermal magnetization M(H) and heat capacity {{C}\\text{p}}(T) measurements on Dy1.8Ca0.2Ti2O7. The spin-ice system Dy2Ti2O7 exhibits a spin-glass type freezing behavior near 16 K. Our frequency dependent {χ\\text{ac}}(T) data of Dy1.8Ca0.2Ti2O7 show that the spin-freezing behavior is significantly influenced by Ca substitution. The effect of partial nonmagnetic Ca2+ substitution for magnetic Dy3+ is similar to the previous study on nonmagnetic isovalent Y3+ substituted Dy2-x Y x Ti2O7 (for low levels of dilution), however the suppression of spin-freezing behavior is substantially stronger for Ca than Y. The Cole-Cole plot analysis reveals semicircular character and a single relaxation mode in Dy1.8Ca0.2Ti2O7 as for Dy2Ti2O7. No noticeable change in the insulating behavior of Dy2Ti2O7 results from the holes produced by 10% Ca2+ substitution for Dy3+ ions.

  17. The crucial role of Mn spiral spin order in stabilizing the Dy-Mn exchange striction in multiferroic DyMnO3.

    Science.gov (United States)

    Wang, H W; Li, C L; Yuan, S L; Wang, J F; Lu, C L; Liu, J-M

    2017-02-01

    DyMnO3 hosts the less addressed duality of multiferroicity, owing to the Dy-Mn exchange striction and inverse Dzyaloshinskii-Moriya interaction between Mn spin pairs. Although the duality in DyMnO3 has been discussed earlier, there remains a question whether the Mn magnetic sublattice is necessarily multiferroic for generating the Dy-Mn exchange striction. In this work, we investigate the multiferroicity of Dy(Mn1-xFex)O3 (0 ≤ x ≤ 0.1) through detailed magnetic and ferroelectric characterization. It is found that Fe-doping continuously suppresses the independent Dy spin order but instead promotes the Dy-Mn(Fe) coupling. This coupling benefits the Dy-Mn(Fe) exchange striction which remarkably enhances the ferroelectric polarization at a low doping level (x ≤ 0.015), beyond which the Mn spiral spin order breaks down leading to collapse of the macroscopic polarization at x ≥ 0.05. This work discloses the crucial role of Mn spiral spin order in stabilizing the Dy-Mn exchange striction and thus highlights the duality of multiferroicity in DyMnO3.

  18. Magnetic ordering temperatures in rare earth metal dysprosium under ultrahigh pressures

    Science.gov (United States)

    Samudrala, Gopi K.; Tsoi, Georgiy M.; Weir, Samuel T.; Vohra, Yogesh K.

    2014-04-01

    Magnetic ordering temperatures in heavy rare earth metal dysprosium (Dy) have been studied using an ultrasensitive electrical transport measurement technique in a designer diamond anvil cell to a pressure of 69 GPa and a temperature of 10 K. Previous studies using magnetic susceptibility measurements at high pressures were able to track magnetic ordering temperature only till 7 GPa in the hexagonal close packed (hcp) phase of Dy. Our studies indicate that the magnetic ordering temperature shows an abrupt drop of 80 K at the hcp-Sm phase transition followed by a gradual decrease that continues till 17 GPa. This is followed by a rapid increase in the magnetic ordering temperatures in the double hcp phase and finally leveling off in the distorted face centered cubic phase of Dy. Our studies reaffirm that 4f-shell remains localized in Dy and there is no loss of magnetic moment or 4f-shell delocalization for pressures up to 69 GPa.

  19. Ferrimagnetic Tb-Fe Alloy Thin Films: Composition and Thickness Dependence of Magnetic Properties and All-Optical Switching

    Directory of Open Access Journals (Sweden)

    Birgit eHebler

    2016-02-01

    Full Text Available Ferrimagnetic rare earth - transition metal Tb-Fe alloy thin films exhibit a variety of different magnetic properties, which depends strongly on composition and temperature. In this study, first the influence of the film thickness (5 - 85 nm on the sample magnetic properties was investigated in a wide composition range between 15 at.% and 38 at.% of Tb. From our results, we find that the compensation point, remanent magnetization, and magnetic anisotropy of the Tb-Fe films depend not only on the composition but also on the thickness of the magnetic film up to a critical thickness of about 20-30 nm. Beyond this critical thickness, only slight changes in magnetic properties are observed. This behavior can be attributed to a growth-induced modification of the microstructure of the amorphous films, which affects the short range order. As a result, a more collinear alignment of the distributed magnetic moments of Tb along the out-of-plane direction with film thickness is obtained. This increasing contribution of the Tb sublattice magnetization to the total sample magnetization is equivalent to a sample becoming richer in Tb and can be referred to as an effective composition. Furthermore, the possibility of all-optical switching, where the magnetization orientation of Tb-Fe can be reversed solely by circularly polarized laser pulses, was analyzed for a broad range of compositions and film thicknesses and correlated to the underlying magnetic properties.

  20. Electrical transport and magnetic ordering in 2Ti3Ge4 (=Dy, Ho and Er) compounds

    Indian Academy of Sciences (India)

    R Nirmala; V Sankaranarayanan; K Sethupathi; A V Morozkin; T Geethakumary; Y Hariharan

    2002-05-01

    New 2Ti3Ge4 ( = Dy, Ho and Er) intermetallic compounds have been synthesized and characterized by X-ray diffraction and low temperature ac magnetic susceptibility, electrical resistivity and thermoelectric power measurements were carried out. The compounds crystallize in the parent, Sm5Ge4-type orthorhombic structure (space group Pnma) and lanthanide contraction is observed as one moves along the rare-earth series. The changeover from paramagnetic to antiferromagnetic phase happens at low temperatures and the ordering temperature scales with the de Gennes factor. The electrical resistivity is metallic with a negative curvature above 100 K. Thermopower displays a weak maximum at temperatures less than 50 K signifying the possible phonon and magnon drag effects.