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Sample records for earth sesquiselenides ln

  1. Syntheses and Structures of Alkali Metal Rare Earth Polyphosphates CsLn(PO3)4 (Ln = La, Ce)

    Institute of Scientific and Technical Information of China (English)

    ZHU Jing; CHENG Wen-Dan; ZHANG Hao; WU Dong-Sheng; ZHAO Dan

    2008-01-01

    Alkali metal-rare earth polyphosphates, CsLn(PO3)4 (Ln = La, Ce), were synthesized by the high temperature solution reaction and studied by single-crystal X-ray diffraction technique. They crystallize in the monoclinic space group P21 (Z = 2) and feature infinite PO4 spiral chains linked with neighboring CsO10 and LnO8 polyhedra. In addition, theoretically calculated energy band structure and density of states (DOS) by the density functional theory(DFT) predict that the solid-state compound CsLa(PO3)4 possesses insulative character.

  2. Phase Behavior of BaLn2Mn2O7 (Ln=Rare Earth) with a Layered Perovskite Structure

    Institute of Scientific and Technical Information of China (English)

    Naoki Kamegashira; Jian Meng; Takeshi Mikami; Hirohisa Satoh; Noriyoshi Kakuta; Kouji Fujita

    2004-01-01

    Many phases appear in BaLn2Mn2O7 family (Ln=rare earth) belonging to one of the Ruddlesden-Popper type compounds, depending upon the experimental conditions such as heating conditions when prepared and composition. Some of these phases were characterized by powder X-ray diffraction method using Rietveld analysis. These phases have only a little difference in crystal structure which has fundamentally K2NiF4 type structure, although the X-ray diffraction patterns are clearly different: a little deformation or tilting of the oxygen octahedron surrounding a central manganese ion composing the main frame of this structure induce these different diffraction patterns. Phase behavior of these compounds, mainly the detailed relation between various phases in BaTb2Mn2O7, was refined including the data of high temperature X-ray diffractometry.

  3. Synthesis of rare earth metal-organic frameworks (Ln-MOFs) and their properties of adsorption desulfurization

    Institute of Scientific and Technical Information of China (English)

    刘想; 王景艳; 李庆远; 蒋赛; 张天浩; 季生福

    2014-01-01

    The rare earth metal-organic frameworks (Ln-MOFs) materials, Ln(BTC)(H2O)·(DMF), were synthesized using the rare earth metal (Ln=Sm, Eu, Tb, Y) and 1,3,5-trimesic acid (BTC) as a metal ion center and ligand, respectively. X-ray diffraction (XRD) and infrared spectroscopy (FT-IR) were employed to characterize the Ln-MOFs structural features. The property of adsorption desul-furization of Ln-MOFs materials was evaluated with thiophene/n-octane as model oil. The results showed that Ln-MOFs with rare earth metals Sm, Eu, Tb and Y had perfect crystalline and good adsorption desulfurization ability. Y(BTC)(H2O)·(DMF) material had a comparatively better activity for the adsorption desulfurization with desulfurization rate up to 80.7%and the sulfur adsorption ca-pacity was found 30.7 mgS/g(Y-MOFs). The Ln-MOFs materials had excellent reusability.

  4. Catalytic combustion of soot particulates over rare-earth substituted Ln2Sn2O7 pyrochlores (Ln=La, Nd and Sm).

    Science.gov (United States)

    Wang, Zhongpeng; Zhu, Hongjian; Ai, Lijie; Liu, Xuhui; Lv, Min; Wang, Liguo; Ma, Zhenmin; Zhang, Zhaoliang

    2016-09-15

    Catalytic combustion is one of the most promising methods for diesel soot removal. Ln2Sn2O7 pyrochlores substituted with different rare-earth (RE) elements (Ln=La, Nd and Sm) were prepared through co-precipitation method for catalytic combustion of soot particulates. The structural, textural and redox properties, together with the oxygen vacancy of the catalysts were investigated systematically. Their catalytic activities were evaluated by both temperature-programmed oxidation and isothermal reaction techniques. With the increasing in RE ionic radius (r), the SnO bond strength in Ln2Sn2O7 pyrochlores evaluated from the stretching IR band was decreased, resulting in the improved reducibility and enhanced oxygen vacancies of catalysts. The increase of oxygen vacancy concentration was further confirmed by photoluminescence (PL) investigations wherein upon excitation with UV radiation, the pyrochlores nanoparticles exhibited strong and sharp transition at 408nm attributed to oxygen vacancies. Catalytic combustion and isothermal reactions revealed that the ignition activity (ignition temperature, T5) and the intrinsic activity (turnover frequency, TOF) were shown to depend correlatedly on redox properties and oxygen vacancy concentrations, both of which were influenced by the substitution of different RE elements. Among the pyrochlore oxides, the as-synthesized La2Sn2O7 sample displayed relatively the highest ignition activity and the largest intrinsic activity with TOF of 2.33×10(-3)s(-1).

  5. Rare-earth metal methylidene complexes with Ln3(μ3-CH2)(μ3-Me)(μ2-Me)3 core structure.

    Science.gov (United States)

    Schädle, Dorothea; Meermann-Zimmermann, Melanie; Maichle-Mössmer, Cäcilia; Schädle, Christoph; Törnroos, Karl W; Anwander, Reiner

    2015-11-07

    Trinuclear rare-earth metal methylidene complexes with a Ln3(μ3-CH2)(μ3-Me)(μ2-Me)3 structural motif were synthesized by applying three protocols. Polymeric [LuMe3]n (1-Lu) reacts with the sterically demanding amine H[NSiMe3(Ar)] (Ar = C6H3iPr2-2,6) in tetrahydrofuran via methane elimination to afford isolable monomeric [NSiMe3(Ar)]LuMe2(thf)2 (4-Lu). The formation of trinuclear rare-earth metal tetramethyl methylidene complexes [NSiMe3(Ar)]3Ln3(μ3-CH2)(μ3-Me)(μ2-Me)3(thf)3 (7-Ln; Ln = Y, Ho, Lu) via reaction of [LnMe3]n (1-Ln; Ln = Y, Ho, Lu) with H[NSiMe3(Ar)] is proposed to occur via an "intermediate" species of the type [NSiMe3(Ar)]LnMe2(thf)x and subsequent C-H bond activation. Applying Lappert's concept of Lewis base-induced methylaluminate cleavage, compounds [NSiMe3(Ar)]Ln(AlMe4)2 (5-Ln; Ln = Y, La, Nd, Ho) were converted into methylidene complexes 7-Ln (Ln = Y, Nd, Ho) in the presence of tetrahydrofuran. Similarly, tetramethylgallate complex [NSiMe3(Ar)]Y(GaMe4)2 (6-Y) could be employed as a synthesis precursor for 7-Y. The molecular composition of complexes 4-Ln, 5-Ln, 6-Y and 7-Ln was confirmed by elemental analyses, FTIR spectroscopy, (1)H and (13)C NMR spectroscopy (except for holmium derivatives) and single-crystal X-ray diffraction. The Tebbe-like reactivity of methylidene complex 7-Nd with 9-fluorenone was assessed affording oxo complex [NSiMe3(Ar)]3Nd3(μ3-O)(μ2-Me)4(thf)3 (8-Nd). The synthesis of 5-Ln yielded [NSiMe3(Ar)]2Ln(AlMe4) (9-Ln; Ln = La, Nd) as minor side-products, which could be obtained in moderate yields when homoleptic Ln(AlMe4)3 were treated with two equivalents of K[NSiMe3(Ar)].

  6. Structure of trihydrated rare-earth acid diphosphates LnHP 2O 7·3H 2O ( Ln=La, Er)

    Science.gov (United States)

    Ben Moussa, S.; Ventemillas, S.; Cabeza, A.; Gutierrez-Puebla, E.; Sanz, J.

    2004-06-01

    In trihydrated lanthanum acid-diphosphates LnHP 2O 7·3H 2O, prepared from acid LnCl 3 and Na 4P 2O 7 solutions (pH=1), two crystal forms were obtained. Layered structures of two representative members of this family have been determined by single-crystal X-ray diffraction (XRD) technique. In the case of orthorhombic LaHP 2O 7·3H 2O (type I), lanthanum cations are ninefold coordinated and diphosphate groups adopt a staggered (alternated) configuration. In the case of triclinic ErHP 2O 7·3H 2O (type II), erbium cations are eightfold coordinated and diphosphate groups adopt an eclipsed configuration. In agreement with Infrared (IR) spectroscopic data, a bended configuration for diphosphate groups has been deduced. In both structures, one-dimensional chains of edge-sharing rare-earth polyhedra are linked together by diphosphate groups to form the phosphate layers. In both diphosphates, PO 4 and HPO 4 environments have been identified by 31P MAS-NMR technique. In the two compounds, OH groups of HPO 4 tetrahedra point out of diphosphate planes interacting with adjacent layers. In La-diphosphate, the interaction between HPO 4 groups and water molecules of adjacent layers is favored; however, in Er-diphosphate, the interaction between phosphate acid groups of contiguous layers is produced. Based on structural information deduced, differences detected in IR and NMR spectra of two disphosphates are discussed.

  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. 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

  9. A new continuous two-step molecular precursor route to rare-earth oxysulfides Ln{sub 2}O{sub 2}S

    Energy Technology Data Exchange (ETDEWEB)

    De Crom, N. [Institute of Condensed Matter and Nanosciences/MOST, Universite Catholique de Louvain, Place Louis Pasteur, 1, L4.01.03, B-1348 Louvain-la-Neuve (Belgium); Devillers, M., E-mail: michel.devillers@uclouvain.be [Institute of Condensed Matter and Nanosciences/MOST, Universite Catholique de Louvain, Place Louis Pasteur, 1, L4.01.03, B-1348 Louvain-la-Neuve (Belgium)

    2012-07-15

    A continuous two-step molecular precursor pathway is designed for the preparation of rare-earth oxysulfides Ln{sub 2}O{sub 2}S (Ln=Y, La, Pr, Nd, Sm-Lu). This new route involves a first oxidation step leading to the rare-earth oxysulfate Ln{sub 2}O{sub 2}SO{sub 4} which is subsequently reduced to the rare-earth oxysulfide Ln{sub 2}O{sub 2}S by switching to a H{sub 2}-Ar atmosphere. The whole process occurs at a temperature significantly lower than usual solid state synthesis (T{<=}650 Degree-Sign C) and avoids the use of dangerous sulfur-based gases, providing a convenient route to the synthesis of the entire series of Ln{sub 2}O{sub 2}S. The molecular precursors consist in heteroleptic dithiocarbamate complexes [Ln(Et{sub 2}dtc){sub 3}(phen)] and [Ln(Et{sub 2}dtc){sub 3}(bipy)] (Et{sub 2}dtc=N,N-diethyldithiocarbamate; phen=1,10-phenanthroline; bipy=2,2 Prime -bipyridine) and were synthesized by a new high yield and high purity synthesis route. The nature of the molecular precursor determines the minimum synthesis temperature and influences therefore the purity of the final Ln{sub 2}O{sub 2}S crystalline phase. - Graphical abstract: A continuous two-step molecular precursor pathway was designed for the preparation of rare-earth oxysulfides Ln{sub 2}O{sub 2}S (Ln=Y, La, Pr, Nd, Sm-Lu), starting from heteroleptic dithiocarbamate complexes. The influence of the nature of the molecular precursor on the minimum synthesis temperature and on the purity of the final Ln{sub 2}O{sub 2}S crystalline phase is discussed. Highlights: Black-Right-Pointing-Pointer A new high yield and high purity synthesis route of rare earth dithiocarbamates is described. Black-Right-Pointing-Pointer These compounds are used as precursors in a continuous process leading to rare-earth oxysulfides. Black-Right-Pointing-Pointer The oxysulfides are obtained under much more moderate conditions than previously described.

  10. Thermal decomposition of heavy rare-earth butanoates, Ln(C3H7CO2)3 (Ln = Er, Tm, Yb and Lu) in argon

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Yue, Zhao; Tang, Xiao

    2016-01-01

    The thermal behaviour of Ln(C3H7CO2)3 (Ln = Er, Tm, Yb or Lu) was studied in argon from room temperature by means of thermogravimetry and differential thermal analysis up to 1400 °C, by infrared spectroscopy, hot-stage optical microscopy and X-ray diffraction. Melting prior to decomposition...... was observed in all four compounds, but its course depends on the rare-earth element. Decomposition to sesquioxides proceeds via the formation of dioxymonocarbonates (Ln2O2CO3) and release of 4-heptanone (C3H7COC3H7) as well as carbon dioxide (CO2) without evidence for an intermediate oxobutanoate stage...

  11. Physicochemical properties of rare earth doped ceria Ce0.9Ln0.1O1.95 (Ln = Nd, Sm, Gd) as an electrolyte material for IT-SOFC/SOEC

    Science.gov (United States)

    Chaubey, Nityanand; Wani, B. N.; Bharadwaj, S. R.; Chattopadhyaya, M. C.

    2013-06-01

    Nanosized crystallites of rare earth doped ceria Ce0.9Ln0.1O1.95 (Ln = Nd, Sm, Gd) a promising electrolyte material for Intermediate Temperature - Solid Oxide Fuel Cells/electrolysis cells have been synthesized by standard ceramic route. Detection of impurities in the samples was done by FTIR spectroscopy. X-ray diffraction studies were used for the determination of phase purity, crystal structure and average crystallite size of the samples. Kinetics involved in phase formation has been discussed. Raman study showed a major band around 465 cm-1 in all the samples, which is attributed to the cubic fluorite structure of ceria. It was also found that for samples Ce0.9Ln0.1O1.95 (Ln = Nd, Sm, Gd) the frequency of F2g shifts to lower value. Electrochemical impedance spectroscopy has been used to measure the ionic conductivity of the samples at elevated temperatures. The Gd doped sample showed the highest grain boundary and total conductivity in comparison to Sm and Nd doped sample. Bulk thermal expansion behavior, sintered densities and micro structural features of the samples have also been studied.

  12. Structures and magnetic properties of rare earth double perovskites containing antimony or bismuth Ba{sub 2}LnMO{sub 6} (Ln=rare earths; M=Sb, Bi)

    Energy Technology Data Exchange (ETDEWEB)

    Otsuka, Shumpei, E-mail: m-nis-s-o@ec.hokudai.ac.jp; Hinatsu, Yukio

    2015-07-15

    A series of double perovskite-type oxides Ba{sub 2}LnMO{sub 6} (Ln=lanthanides; M=Sb, Bi) were synthesized and their structures were studied. The Ln and M are structurally ordered in the rock-salt type at the B-site of the perovskite ABO{sub 3}. For Ba{sub 2}PrBiO{sub 6} and Ba{sub 2}TbBiO{sub 6}, it has been found that the disordering between Ln ion and Bi ion occurs at the B-site of the double perovskite and both the Pr (Tb) and Bi exist in two oxidation state in the same compound from the analysis of the X-ray diffraction and magnetic susceptibility data. Magnetic susceptibility measurements show that all these compounds are paramagnetic and have no magnetic ordering down to 1.8 K. - Graphical abstract: Tolerance factor for Ba{sub 2}LnMO{sub 6} (M=Sb, Bi) plotted against the ionic radius of Ln{sup 3+}. We have found that there is a clear relation between crystal structures and tolerance factors. - Highlights: • The Ln and M ions are structurally ordered in the rock-salt type at the B-site. • The disordering between Pr (Tb) ion and Bi ion occurs at the B-site. • Ba{sub 2}LnMO{sub 6} (M=Sb, Bi) have no magnetic ordering down to 1.8 K.

  13. Catalysis of the rare earth containing mixed oxides Ln2CuO4 in phenol hydroxylation

    Institute of Scientific and Technical Information of China (English)

    刘持标; 赵震; 叶兴凯; 吴越

    1997-01-01

    Mixed oxides Ln2CuO4±λ(Ln=La,Pr,Nd,Sm,Gd) with K2NiF4 structure were prepared Their crystal structures were studied with XRD and IR spectra.Meanwhile,the average valence of Cu ions and non stoichiometric oxygen (λ) were determined through chemical analyses.Catalysis of the above-mentioned mixed oxides in the phenol hydroxylation was investigated.Results show that the catalysis of these mixed oxides has close relation with their structures and composition.Substitution of A site atom in Ln2CuO4λ has a great influence on then eatalysis in the phenol hydroxylation.

  14. 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)

  15. Pyroelectric properties of the monoclinic rare earth nitrates A{sub 2}Ln(NO{sub 3}){sub 5}.4H{sub 2}O (A = NH{sub 4}, Rb; Ln = La, Ce)

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, Matthias; Andersen, Lionel; Becker, Petra; Bohaty Ladislav [Koeln Univ. (Germany). Inst. fuer Kristallographie

    2015-07-01

    The pyroelectric effect of four isomorphic monoclinic (space group Cc), non-ferroelectric rare earth nitrates A{sub 2}Ln(NO{sub 3}){sub 5}.4H{sub 2}O (A = NH{sub 4}, Rb; Ln = La, Ce) was investigated in the temperature range between 100 K and 300 K, using a home-made continuous-flow cryostat for measurements of pyroelectric currents. The symmetry-allowed temperature-dependent change of orientation of the pyroelectric vector p within the mirror plane is unusually large, showing a rotation of p of 148 , 129 , 36 and 40 for (NH{sub 4}){sub 2}La(NO{sub 3}){sub 5}.4H{sub 2}O, (NH{sub 4}){sub 2}Ce(NO{sub 3}){sub 5}.4H{sub 2}O, Rb{sub 2}La(NO{sub 3}){sub 5}.4H{sub 2}O and Rb{sub 2}Ce(NO{sub 3}){sub 5}.4H{sub 2}O, respectively, while changing the temperature from 100 K to 300 K in each case. The pyroelectric coefficients are up to ten times larger than p{sub 3} of tourmaline. In addition, new data of the pyroelectric coefficients of Li{sub 2}SO{sub 4}.H{sub 2}O and BiB{sub 3}O{sub 6} and their temperature dependence are given.

  16. 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.

  17. Crystallization and structural approaches of rare earths aluminosilicate glasses (Ln = La, Y, Sc); Comportement a la cristallisation et approches structurales des verres aluminosilicates de terres rares (Ln = La, Y et Sc)

    Energy Technology Data Exchange (ETDEWEB)

    Sadiki, N.; Coutures, J.P. [PROMES, CNRS, Rambla de la Thermodynamique, Tecnosud, 66100 Perpignan (France); Hennet, L.; Florian, P.; Vaills, Y.; Massiot, D. [CEMHTI, CNRS, 1D av. de la Recherche Scientifique, 45071 Orleans Cedex 2 (France)

    2010-07-01

    The crystallization behaviour of aluminosilicate glasses of lanthanum, yttrium and scandium has been studied by DTA, XRD, SEM-EDX and EPMA analysis. Young modulus E and hardness H have been measured by using nano-indentation and elastic modulus C{sub 11} and C{sub 44} by Brillouin scattering. The Young modulus measured by nano-indentation agree to those determined by Brillouin scattering and those calculated using Makishima-Mackenzie and Rocherulle model's. The results of DTA analysis indicate that (a) the glass transition temperatures T{sub g} are higher for yttrium and scandium containing glasses than their lanthanum counterparts, the melting observed in the yttrium glasses and recently in the scandium glasses correspond to the ternary eutectic Ln{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-SiO{sub 2} (Ln = Y, Sc) (b) the thermal stability is strongly related to the ionic radii of the rare earth. The last results obtained on scandium containing glasses confirm this hypothesis. The XRD results show that the nature of the observed crystallized phases is consistent with the phase diagrams. We also have investigated by NMR-MAS of {sup 27}Al (high field- 17.6 T) these glasses. The results indicate that Al(V) species are correlated to the ionic radii of the rare earth. X-rays and neutron scattering experiments have been respectively performed on the high energy diffraction beam lines ID11 and ID15 at ESRF. The interatomic distances and first-shell coordination numbers were determined. The results are consistent with those performed by NMR-MAS. (authors)

  18. Crystal Structure of Rare Earth Acrylates[Ln2(CH2 CHCOO)6·3H2O]·3H2O(Ln=Ce,Nd)%两种丙烯酸盐[Ln2(CH2CHCOO)6·3H2O]·3H2O(Ln=Ce;Nd)的单晶结构

    Institute of Scientific and Technical Information of China (English)

    钱玉英; 褚晓东; 姚有为

    2011-01-01

    Crystal strudures of [Ln2 (CH2CHCOO)6·3H2O](Ln = Ce,Nd) were characterized by using X - ray single crystal analysis. The title compounds are iso - structural: monoclime system, apace group P21/c with a= 1.02099 (13)nm,b = 1.52294(19) nm,c = 2.0325(3) nm,β= 100.838 (2)°, V = 3.1039 (7) nm3 for [ Ce2 ( CH2CHCOO) 6·3H2O] ;α=1.01978(8) nm, b=1.50979 (12) nm, c=2.02712 (16) nm,β=100.881 (1)°, V = 3.0650 (4) nm3 for [ND2 (CH2CHCOO)6·3H2O]. There are two independent Ln ions in the asymmetric unit, which are located in nona - coor-dinated and deca - coordinated environments respectively. The two Ln ions are bridged togetber by two μ2 - oxygen atoms of two independent acrylates, resulting in left - handed and right - handed helical chains. Hydrogen network are built up from helical chains and water molecules located between two neighbor chains. giying rise to three - dimensional stack.%采用X射线单晶衍射法,解析了[Ln2(CH:CHCOO)6·3H2O]·3H2O(Ln=Ce;Nd)的结构.结果表明标题化合物属同构:属单斜晶系(空间群P2(1)/c);[Ce2(CH2CHCOO)6·3H2O]·3H2O晶胞参数α=1.02099(13)nm,b=1.52294(19)nm,c=2.0325(3)nin,/3=100.838(2)°,V=3.1039(7)nm3;[Nd2(CH2CHCOO)6·3H2O]·3H2O晶胞参数α=1.01978(8)nm,6=1.50979(12)nm,c=2.02712(16)nm,β=100.881(1)°,V=3.0650(4)nm3.化合物不对称结构单元中含有两个独立的稀土中心离子,分别处九、十配位环境中.两个稀土离子由两个独立的丙烯酸μ2-氧桥联形成左手和右手螺旋链.螺旋链通过链间的水分子形成氢键网络,堆垛成三维结构.

  19. Electronic phase separation in the rare-earth manganates (La sub 1 sub - sub x Ln sub x) sub 0 sub . sub 7 Ca sub 0 sub . sub 3 MnO sub 3 (Ln = Nd, Gd and Y)

    CERN Document Server

    Sudheendra, L

    2003-01-01

    Electron transport and magnetic properties of three series of manganates of the formula (La sub 1 sub - sub x Ln sub x) sub 0 sub . sub 7 Ca sub 0 sub . sub 3 MnO sub 3 with Ln = Nd, Gd and Y, wherein only the average A-site cation radius (r sub A ) and associated disorder vary, without affecting the Mn sup 4 sup + /Mn sup 3 sup + ratio, have been investigated in an effort to understand the nature of phase separation. All three series of manganates show saturation magnetization characteristic of ferromagnetism, with the ferromagnetic T sub c decreasing with increasing x up to a critical value of x, x sub c (x sub c = 0.6, 0.3, 0.2 respectively for Nd, Gd, Y). For x > x sub c , the magnetic moments are considerably smaller, showing a small increase around T sub M , the value of T sub M decreasing slightly with increase in x or decrease in (r sub A ). The ferromagnetic compositions (x x sub c are insulating. The magnetic and electrical resistivity behaviour of these manganates is consistent with the occurrence...

  20. First principles investigation of structural, electronic, elastic and thermal properties of rare-earth-doped titanate Ln2TiO5

    Directory of Open Access Journals (Sweden)

    Hui Niu

    2012-09-01

    Full Text Available Systematic first-principles calculations based on density functional theory were performed on a wide range of Ln2TiO5 compositions (Ln = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy and Y in order to investigate their structural, elastic, electronic, and thermal properties. At low temperature, these compounds crystallize in orthorhombic structures with a Pnma symmetry, and the calculated equilibrium structural parameters agree well with experimental results. A complete set of elastic parameters including elastic constants, Hill's bulk moduli, Young's moduli, shear moduli and Poisson's ratio were calculated. All Ln2TiO5 are ductile in nature. Analysis of densities of states and charge densities and electron localization functions suggests that the oxide bonds are highly ionic with some degree of covalency in the Ti-O bonds. Thermal properties including the mean sound velocity, Debye temperature, and minimum thermal conductivity were obtained from the elastic constants.

  1. Preparation of Ln3-xEuxS4 (Ln=Ce,Pr,and Nd) ceramics by pressureless sintering

    Institute of Scientific and Technical Information of China (English)

    YUAN HaiBin; ZHANG JianHui; YU RuiJin; SU Oiang

    2009-01-01

    The preparation of ternary rare earth sulfides of Ln3-xEuxS4(Ln = Ce,Pr,and Nd) ceramics was investigated,and the effect of Eu substitution on Ln3-xEuxS4 ceramics was also studied.Ln3-xEuxS4 powders were synthesized by the sulfurization of their oxide powders using carbon disulfide gas.Ln3-xEuxS4 ceramics were sintered by pressure-less sintering method.All pressureless sintered Ln3-xEuxS4 ceramics crystallized in y-phase.It was found that Eu substitution could improve the density of Ln3-xEuxS4 ceramics.Furthermore,Eu substitution might narrow the optical band gaps of Ln3-xEuxS4 ceramics.

  2. Homoleptic rare earth dipyridylamides [Ln2(N(NC5H4)2)6], Ln = Ce, Nd, Sm, Ho, Er, Tm, Yb, and Sc: metal oxidation by the amine melt and in 1,2,3,4-tetrahydroquinoline with the focus of different metal activation by amalgams, liquid ammonia, and microwaves.

    Science.gov (United States)

    Müller-Buschbaum, Klaus; Quitmann, Catharina C

    2006-03-20

    Homoleptic dimeric dipyridylamide complexes of the rare earth elements are obtained by solvent-free oxidation reactions of the metals with melts of 2,2'-dipyridylamine. As the thermal stabilities of the ligand as well as the amide complexes are limiting factors in these high-temperature syntheses, several different metal activation procedures have been investigated: the formation of Ln amalgams and dissolution of the metals in liquid ammonia as well as coupling to microwaves. For comparison with a solvent that shows low solubility of the metals and products, reactions in 1,2,3,4-tetrahydroquinoline were also carried out. For all lanthanides and group 3 metals used homoleptic dimers of the formula [Ln(2)(Dpa)(6)], Ln = Ce (1), Nd (2), Sm (3), Ho (4), Er (5), Tm (6), Yb (7), and Sc (8) and Dpa- = (C5H4N)2N-, were obtained, all containing trivalent rare earth ions with a distorted square antiprismatic nitrogen coordination. Due to the large differences in the ionic radii of the metal ions, two different structure types are found that crystallize in the space groups P2(1)/c and P2(1)/n with the border of the two types being between Tm and Yb. The orientations of two 1,3/1,3-double chelating and linking dipyridylamide ligands (Dpa(-) = (C(5)H(4)N)(2)N(-)) result in different overall orientations of the dimers and thus two structure types. All compounds were identified by single-crystal X-ray analysis. Mid-IR, far IR, and Raman spectroscopy, microanalyses, and simultaneous DTA/TG as well as mass spectrometry regarding their thermal behavior were also carried out to characterize the products. Crystal data for the two types follow. Ce (1): P2(1)/n; T = 170(2) K; a = 1063.0(1), b = 1536.0(1), c = 1652.0(2) pm; beta = 101.60(1) degrees ; V = 2642.2(3) x 10(6) pm(3); R(1) for F(o) > 4sigma(F(o)) = 0.046, wR(2) = 0.120. Sc (8): P2(1)/c; T = 170(2) K; a = 1073.0(1), b = 1506.2(2), c = 1619.8(2) pm; beta = 103.16(9) degrees ; V = 2548.9(5) x 10(6) pm(3); R(1) for F(o) > 4sigma

  3. A Safe and Brief Way for Preparing Anhydrous LnCl3 (Ln=Sc, Y, La to Lu)

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Anhydrous lanthanide chlorides LnCl3 (Ln=Sc, Y, La to Lu except for Pm), which are difficult to prepare in other ways, were prepared by chemical vapor transport (CVT) process. Rare earth oxide reacted with Al2Cl6 at 300℃ to produce LnCl3, which was then separated from other solids by means of CVT at a temperature gradient from 400 to 180℃. Residual Al2Cl6 (g) was removed by carrier of dry N2 gas at 200℃. The yielding rates were >90%, and the purity of products was >99.5%.

  4. Microwave synthesis and photoluminescent properties of Sr2CeO4/Ln3+ (Ln = Er, Ho, Tm)

    Institute of Scientific and Technical Information of China (English)

    KANG Hongge; SONG Huihua; WANG Jiye; Sill Shikao

    2007-01-01

    Sr2CeO4/Ln3+ (Ln = Er, Ho, Tm) phosphors were synthesized with the microwave radiation method for the first time. The luminescent properties of the samples were investi-gated and the up-conversion luminescence of Er3+, Ho3+ and Tm3+ doped Sr2CeO4 phosphors was observed. The spectra indicate that the energy transfer takes place from the triplet excited state ofMLCT (metal-to-ligand charge transfer) state for Sr2CeO4 (sensitizer) to the rare earth ions (activator).

  5. Vibrational and excited electronic states of six-coordinate rare earth complexes with 2,6-lutidine n-oxide: [Ln(C 7H 9NO) 6](ClO 4) 3·H 2O (Ln=Pr,Nd,Sm,Eu,Gd,Dy)

    Science.gov (United States)

    Ban-Oganowska, H.; Godlewska, P.; Macalik, L.; Hanuza, J.; Oganowski, W.; Hermanowicz, K.

    2002-09-01

    A series of six-coordinate complexes of 2,6-lutidine N-oxide (C 7H 9NO) with praseodymium, neodymium, samarium, europium, gadolinium and dysprosium has been synthesised and chemically characterised. FT-IR and FT-Raman spectra in the range 80-4000 cm -1 as well as electronic absorption and emission spectra in the range 4000-50,000 cm -1 have been measured. The Lorenzian deconvolution of the vibrational contour in the 100-300 cm -1 region has been used in the discussion of the molecular and site symmetries of the Ln 3+ ion situated in the oxygen polyhedron. The sequence of the electronic levels for all RE ions has been obtained and assigned to the respective transitions.

  6. Magnetic properties of the layered oxypnictides (LnOMnAs (Ln = La, Ce, Pr, Nd

    Directory of Open Access Journals (Sweden)

    Morosawa Y.

    2014-07-01

    Full Text Available We have investigated the rare earth elements dependence on the magnetism to understand the contribution to physical properties of the 4f electrons of (LnOMnAs (Pn = La, Ce, Pr, Nd. (CeOMnAs, (PrOMnAs and (NdOMnAs shows the antiferromagnetic behaviors at low temperature. (CeOMnAs and (NdOMnAs have the magnetic anomalies around 34 K and 24 K, respectively. So, it is speculated that the anomalies depend on the Mn -Mn distance directly

  7. Observation of unusual topological surface states in half-Heusler compounds LnPtBi (Ln=Lu, Y).

    Science.gov (United States)

    Liu, Z K; Yang, L X; Wu, S-C; Shekhar, C; Jiang, J; Yang, H F; Zhang, Y; Mo, S-K; Hussain, Z; Yan, B; Felser, C; Chen, Y L

    2016-09-27

    Topological quantum materials represent a new class of matter with both exotic physical phenomena and novel application potentials. Many Heusler compounds, which exhibit rich emergent properties such as unusual magnetism, superconductivity and heavy fermion behaviour, have been predicted to host non-trivial topological electronic structures. The coexistence of topological order and other unusual properties makes Heusler materials ideal platform to search for new topological quantum phases (such as quantum anomalous Hall insulator and topological superconductor). By carrying out angle-resolved photoemission spectroscopy and ab initio calculations on rare-earth half-Heusler compounds LnPtBi (Ln=Lu, Y), we directly observe the unusual topological surface states on these materials, establishing them as first members with non-trivial topological electronic structure in this class of materials. Moreover, as LnPtBi compounds are non-centrosymmetric superconductors, our discovery further highlights them as promising candidates of topological superconductors.

  8. Sol-gel preparation and electrical behaviour of Ln: YAG (Ln = Ce, Nd, Ho, Er

    Directory of Open Access Journals (Sweden)

    AIVARAS KAREIVA

    2003-09-01

    Full Text Available A sol-gel method has been developed to prepare pure yttrium aluminum garnet, Y3Al5O12 (YAG, and rare-earth substituted (Ce-Y3Al5O12, Nd-Y3Al5O12, Ho-Y3Al5O12, and Er-Y3Al5O12 samples. The XRD patterns of the polycrystalline powders sintered at 1000ºC showed the formation of monophasic garnet materials. The micro-structural features in the polycristalline samples were studied by scanning electron microscopy. A homogeneous distribution of rare-earth dopants in the YAG lattice was achieved in all of the cases. Electrical conductivity measurements were also performed on the compacts of sol-gel derived Ln-YAG samples. In contrast to the expected dielectric behaviour, the conducting properties of the examined specimens indicate metallic behaviour with the resistivity increasing gradually with increasing temperature.

  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. COMPARISION OF THE COLOR PROPERTIES OF COMPOUNDS Ln2Ce2O7 AND Ln2CeZrO7

    Directory of Open Access Journals (Sweden)

    B. Hablovicova

    2015-09-01

    Full Text Available Pyrochlore type pigments Ln2Ce2O7 and Ln2CeZrO7 (Ln = Nd, Sm, Gd, Dy, Er, Yb and Y prepared by solid-state reaction were investigated. Effect of rare earths and zirconium ions and calcination temperature (1400, 1500 and 1600oC for Ln2Ce2O7 and 1400, 1450 and 1500 C for Ln2CeZrO7 on their color properties in organic matrix and ceramic glazes, particle size distribution and phase composition were evaluated. The most interesting shades achieve compounds with the highest calcination temperature. Their colors depend on used rare earth ions (shades change from green, cross yellow to pink in organic mass and from green, cross yellow-green to orange in ceramic glazes, while compounds without zirconium have better color properties. Pigments Ln2Ce2O7 calcined at 1600 C are single-phase (except Yb2Ce2O7.

  11. Computational study of LnGaO3 (Ln = La Gd) perovskites

    Science.gov (United States)

    Senyshyn, A.; Ehrenberg, H.; Vasylechko, L.; Gale, J. D.; Bismayer, U.

    2005-10-01

    Atomistic simulation techniques have been used to study the thermal properties of perovskite-type LnGaO3 (Ln = La-Gd). A set of interatomic potentials describing interatomic interactions in these compounds was developed and tested over a wide temperature range through utilizing free energy minimization. The predicted dielectric constants, thermal expansion coefficients, phonon density of states and its projections, heat capacity and entropy, elastic moduli, Grüneisen parameters, surface energies for main crystallographic directions and Debye temperatures are in good agreement with the limited available experimental data. Perovskite-type LnGaO3 (Ln = La-Gd) compounds have been examined under conditions to which substrate materials are typically subjected. Only a narrow region in the phase diagram of LnGaO3 (Ln = La-Gd) and their solid solutions is recommended for use in substrate applications.

  12. Computational study of LnGaO{sub 3} (Ln = La-Gd) perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Senyshyn, A [Institute for Materials Science, Darmstadt University of Technology, Petersenstrasse 23, D-64287 Darmstadt (Germany); Ehrenberg, H [Institute for Materials Science, Darmstadt University of Technology, Petersenstrasse 23, D-64287 Darmstadt (Germany); Vasylechko, L [Semiconductor Electronics Department, Lviv Polytechnic National University, 12 Bandera Street, 79013 Lviv (Ukraine); Gale, J D [Department of Applied Chemistry, Nanochemistry Research Institute, Curtin University of Technology, PO Box U1987, 6845 Perth, Western (Australia); Bismayer, U [Mineralogisch-Petrographisches Instituet, Universitaet Hamburg, Grindelallee 48, D-20146 Hamburg (Germany)

    2005-10-05

    Atomistic simulation techniques have been used to study the thermal properties of perovskite-type LnGaO{sub 3} (Ln = La-Gd). A set of interatomic potentials describing interatomic interactions in these compounds was developed and tested over a wide temperature range through utilizing free energy minimization. The predicted dielectric constants, thermal expansion coefficients, phonon density of states and its projections, heat capacity and entropy, elastic moduli, Grueneisen parameters, surface energies for main crystallographic directions and Debye temperatures are in good agreement with the limited available experimental data. Perovskite-type LnGaO{sub 3} (Ln = La-Gd) compounds have been examined under conditions to which substrate materials are typically subjected. Only a narrow region in the phase diagram of LnGaO{sub 3} (Ln = La-Gd) and their solid solutions is recommended for use in substrate applications.

  13. Influence of the crystal structure on the stability of Ln{sup 2+} in strontium borates

    Energy Technology Data Exchange (ETDEWEB)

    Dotsenko, V.P. [Physico-Chemical Institute, Ukrainian Academy of Sciences, 86 Lustdorfskaya str., 65080 Odesa (Ukraine)], E-mail: ssclab@ukr.net; Berezovskaya, I.V.; Efryushina, N.P. [Physico-Chemical Institute, Ukrainian Academy of Sciences, 86 Lustdorfskaya str., 65080 Odesa (Ukraine); Voloshinovskii, A.S.; Stryganyuk, G.B. [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya str., 29005 Lviv (Ukraine)

    2007-04-15

    The results of luminescence measurements on Ln (Eu, Yb) doped alkaline earth (M=Ca,Sr) borates M{sub 3}(BO{sub 3}){sub 2}, MB{sub 2}O{sub 4}, M{sub 2}B{sub 5}O{sub 9}X(X=Cl,Br), MB{sub 6}O{sub 10}, MB{sub 4}O{sub 7} after high-temperature annealing in various atmospheres are reported and discussed. The stability of Ln{sup 2+}(Ln=Eu,Yb) is found to increase in the sequence Sr{sub 3}(BO{sub 3}){sub 2}Ln{sup 3+}. A simple criterion is proposed to predict the stability of Ln{sup 2+} in alkaline earth borates.

  14. Syntheses and Structures of the Quaternary Copper Tellurides K 3Ln4Cu 5Te 10 ( Ln=Sm, Gd, Er), Rb 3Ln4Cu 5Te 10 ( Ln=Nd, Gd), and Cs 3Gd 4Cu 5Te 10

    Science.gov (United States)

    Huang, Fu Qiang; Ibers, James A.

    2001-09-01

    Six quaternary alkali-metal rare-earth copper tellurides K3Ln4Cu5Te10 (Ln=Sm, Gd, Er), Rb3Ln4Cu5Te10 (Ln=Nd, Gd), and Cs3Gd4Cu5Te10 have been synthesized at 1123 K with the use of reactive fluxes of alkali-metal halides ACl (A=K, Rb, Cs). All crystallographic data were collected at 153 K. These compounds crystallize in space group Pnnm of the orthorhombic system with two formula units in cells of dimensions (A3Ln4, a, b, c (Å)): K3Sm4, 16.590(2), 17.877(2), 4.3516(5); K3Gd4, 16.552(4), 17.767(4), 4.3294(9); K3Er4, 16.460(4), 17.550(4), 4.2926(9); Rb3Nd4, 17.356(1), 17.820(1), 4.3811(3); Rb3Gd4, 17.201(2), 17.586(2), 4.3429(6); Cs3Gd4, 17.512(1), 17.764(1), 4.3697(3). The corresponding R1 indices for the refined structures are 0.0346, 0.0315, 0.0212, 0.0268, 0.0289, and 0.0411. The three K3Ln4Cu5Te10 structures belong to one structure type and the Rb3Ln4Cu5Te10 (Ln=Nd, Gd) and Cs3Gd4Cu5Te10 structures belong to another one, the difference being the location of one of the three unique Cu atoms. Both structure types are three-dimensional tunnel structures that contain similar Ln/Te fragments built from LnTe6 octahedra and CuTe4 tetrahedra. The CuTe4 tetrahedra form 1∞[CuTe5-3] and 1∞[CuTe3-2] chains. The alkali-metal atoms, which are in the tunnels, are coordinated to seven or eight Te atoms.

  15. Rhombus-shaped tetranuclear [Ln4] complexes [Ln = Dy(III) and Ho(III)]: synthesis, structure, and SMM behavior.

    Science.gov (United States)

    Chandrasekhar, Vadapalli; Hossain, Sakiat; Das, Sourav; Biswas, Sourav; Sutter, Jean-Pascal

    2013-06-03

    The reaction of a new hexadentate Schiff base hydrazide ligand (LH3) with rare earth(III) chloride salts in the presence of triethylamine as the base afforded two planar tetranuclear neutral complexes: [{(LH)2Dy4}(μ2-O)4](H2O)8·2CH3OH·8H2O (1) and [{(LH)2Ho4}(μ2-O)4](H2O)8·6CH3OH·4H2O (2). These neutral complexes possess a structure in which all of the lanthanide ions and the donor atoms of the ligand remain in a perfect plane. Each doubly deprotonated ligand holds two Ln(III) ions in its two distinct chelating coordination pockets to form [LH(Ln)2](4+) units. Two such units are connected by four [μ2-O](2-) ligands to form a planar tetranuclear assembly with an Ln(III)4 core that possesses a rhombus-shaped structure. Detailed static and dynamic magnetic analysis of 1 and 2 revealed single-molecule magnet (SMM) behavior for complex 1. A peculiar feature of the χM" versus temperature curve is that two peaks that are frequency-dependent are revealed, indicating the occurrence of two relaxation processes that lead to two energy barriers (16.8 and 54.2 K) and time constants (τ0 = 1.4 × 10(-6) s, τ0 = 7.2 × 10(-7) s). This was related to the presence of two distinct geometrical sites for Dy(III) in complex 1.

  16. Structures, magnetic and dielectric properties of the ordered double perovskites LnPbNiSbO6 (Ln = La, Pr)

    Science.gov (United States)

    Han, Lin; Bai, Yijia; Liu, Xiaojuan; Yao, Chuangang; Meng, Junling; Liang, Qingshuang; Wu, Xiaojie; Meng, Jian

    2014-09-01

    The crystal structures, magnetic and dielectric properties for the ordered double perovskites LnPbNiSbO6 (Ln = La, Pr) have been investigated. Rietveld refinements of x-ray diffraction data have been indexed for the monoclinic symmetry in space group P21/n (No. 14) and a highly rock-salt ordered arrangement of NiO6 and SbO6 octahedra. The B-site lattices are distorted strongly due to the substitution of rare Earth ions at the A-site. The magnetization measurements show an antiferromagnetic ordering. The effective magnetic moments μ eff are larger than the spin-only values, suggesting that the orbital component for Ni2+ is significant. The maximum values of isothermal magnetization increase due to the lattice distortion of BO6 octahedra, which may weaken the antiferromagnetic interaction via Ni2+-O-Sb5+-O-Ni2+ paths. The dielectric constants for LaPbNiSbO6 present frequency dependence and the tan δ curves exhibit relaxor-like dielectric response. The ɛ‧ decreases with the reduction of the magnetic moments of B-site transition metal ions, which reveals a relationship between the dielectric and magnetic properties.

  17. Investigation about thermophysical properties of Ln{sub 2}Ce{sub 2}O{sub 7} (Ln = Sm, Er and Yb) oxides for thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Hongsong, Zhang, E-mail: zhs761128@163.com [Department of Mechanical Engineering, Henan Institute of Engineering, Zhengzhou 450007 (China); Jianguo, Lv [City College, Kunming University of Science and Technology, Kunming 650050 (China); Gang, Li; Zheng, Zhang; Xinli, Wang [Department of Mechanical Engineering, Henan Institute of Engineering, Zhengzhou 450007 (China)

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► We successfully prepared three types of new rare earth cerium oxides. ► We measured their thermophysical properties. ► These new ceramics can be explored as candidate ceramics for thermal barrier coatings. -- Abstract: Three kinds of rare earth cerium oxides – Ln{sub 2}Ce{sub 2}O{sub 7} (Ln = Sm, Er and Yb) were prepared by solid state reaction method. Their phase compositions, microstructures and thermophysical properties were investigated. Results of X-ray diffraction reveal that pure Ln{sub 2}Ce{sub 2}O{sub 7} (Ln = Sm, Er and Yb) oxides with fluorite structure are successfully synthesized in the current research. Scanning electrical microscopy results show that their microstructures are dense and no other un-reacted oxides or inter-phases exist in the interfaces between grains. Their thermal expansion coefficients are higher than those of YSZ, while their thermal conductivities are lower than those of YSZ. The decreasing ionic radius from Sm{sup 3+} to Yb{sup 3+} results in the descending thermal expansion coefficients from Sm{sub 2}Ce{sub 2}O{sub 7} to Yb{sub 2}Ce{sub 2}O{sub 7}. The effective phonon scattering by atomic weight difference contributes to the decreasing thermal conductivities from Sm{sub 2}Ce{sub 2}O{sub 7} to Yb{sub 2}Ce{sub 2}O{sub 7}. These results imply that synthesized rare earth cerium oxides have potentials to be used as novel candidate materials for thermal barrier coatings in the future.

  18. Facile fabrication and upconversion luminescence enhancement of LaF3:Yb3+/Ln3+@SiO2 (Ln = Er, Tm) nanostructures decorated with Ag nanoparticles.

    Science.gov (United States)

    He, Enjie; Zheng, Hairong; Dong, Jun; Gao, Wei; Han, Qingyan; Li, Junna; Hui, Le; Lu, Ying; Tian, Huani

    2014-01-31

    A novel hybrid nanostructure, that is a Ag nanoparticle decorated LaF(3):Yb(3+)/Ln(3+)@SiO(2) nanosphere (Ln=Er, Tm), was constructed by a facile strategy, and characterized by XRD, TEM, FTIR, XPS and UV-vis-NIR absorption. Obvious spectral broadening and red-shift on the surface plasmon resonance were obtained by adjusting the size and configuration of Ag nanoparticles. Effective upconversion luminescence enhancements for Er(3+) and Tm(3+) containing samples were obtained. It is suggested that the luminescence enhancement results from both the excitation and emission processes, and the configuration of the studied hybrid nanostructure is an efficient system to enhance the luminescence emission of rare earth doped nanomaterials. It is believed that the enhancement from the hybrid nanostructure will find great potential in the development of photovoltaic solar cells.

  19. Solution-combustion synthesis of Bi1–LnO1.5 (Ln = Y and La–Yb) oxide ion conductors

    Indian Academy of Sciences (India)

    Manjunath B Bellakki; A S Prakash; C Shivakumara; M S Hegde; A K Shukla

    2006-08-01

    Cubic fluorite related Bi1–LnO1.5 (Ln = Y and La–Yb) phases are synthesized by solutioncombustion method using glycine as the fuel. The cubic fluorite phase is stabilized with 25 mole% of rare earth cations. The lattice parameter of cubic phase increases linearly with size of the lanthanide ion. The synthesized powders are nano-metric in size and exhibit excellent compactability and reach 98% densification even on short period of sintering. The oxides with relatively larger cations Nd, Sm, Eu, Pr and Gd with 25 mole% composition transform to rhombohedral structure while others retain cubic upon sintering. All the phases show high oxide–ion conductivity and the values obtained are in good agreement with the reported values.

  20. Facile patterning of luminescent GdVO{sub 4}:Ln (Ln = Eu{sup 3+}, Dy{sup 3+}, Sm{sup 3+}) thin films by microcontact printing process

    Energy Technology Data Exchange (ETDEWEB)

    Wang Dong; Yang Piaoping; Cheng Ziyong, E-mail: zycheng@ciac.jl.cn; Wang Wenxin; Ma Pingan; Zhai Xuefeng; Lin Jun, E-mail: jlin@ciac.jl.cn [Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, State Key Laboratory of Rare Earth Resource Utilization (China)

    2012-01-15

    Ordered arrays of luminescent GdVO{sub 4}:Ln (Ln = Eu{sup 3+}, Dy{sup 3+}, Sm{sup 3+}) films with dot patterns have been successfully fabricated via microcontact printing method. The soft-lithography process utilizes a PDMS elastomeric mold as the stamp combined with a Pechini-type sol-gel process to produce luminescent patterns on quartz plates, in which a GdVO{sub 4}:Ln (Ln = Eu{sup 3+}, Dy{sup 3+}, Sm{sup 3+}) precursor solution was employed as ink. The ordered luminescent GdVO{sub 4}:Ln patterns were revealed by optical microscopy and their microstructure, consisting of nanometer-scale particles, as demonstrated by scanning electronic microscopy observations. In addition, photoluminescence and cathodoluminescence were carried out to characterize the patterned GdVO{sub 4}:Ln (Ln = Eu{sup 3+}, Dy{sup 3+}, Sm{sup 3+}) samples. Upon UV-light or electron-beam irradiation, the rare earth ions Eu{sup 3+}, Dy{sup 3+}, and Sm{sup 3+} in the crystalline GdVO{sub 4} host show their characteristic transitions dominated by {sup 5}D{sub 0}-{sup 7}F{sub 2}, {sup 4}F{sub 9/2}-{sup 6}H{sub 13/2} ,and {sup 4}G{sub 5/2}-{sup 6}H{sub 7/2}, respectively. These results make the combining soft lithography with a Pechini-type sol-gel route have potential applications as rare-earth luminescent pixels for next-generation field-emission display devices.

  1. Preparation, crystal structure, spectra and energy levels of the trivalent ytterbium ion doped into rare earth stannates

    Science.gov (United States)

    Ning, Kaijie; Zhang, Qingli; Sun, Dunlu; Yin, Shaotang; Jiang, Haihe

    2012-01-01

    Yb3+-doped Rare Earth Stannates Ln2Sn2O7(Ln=Y, Gd) with space group Fd3m were synthesized by co-precipitation technique. Their structures were determined by Rietveld refinement to their X-ray diffraction, and their atom coordinates, lattice parameters and temperature factors were given. From emission, absorption and excitation spectra, the energy levels of Yb3+ in Ln2Sn2O7(Ln=Y, Gd) were assigned and the crystal field parameters were fitted to energy splitting of Yb3+-doped Ln2Sn2O7 (Ln=Y, Gd).

  2. Regionální a strukturální dopady PZI

    OpenAIRE

    Mazánková, Ester

    2007-01-01

    Cílem diplomové práce je zhodnocení regionálních a strukturálních dopadů PZI na Českou republiku. Snahou je zaprvé vysvětlit všeobecná východiska PZI a popsat faktory ovlivňující příliv zahraničního kapitálu do České republiky vůbec a také regionálně. Za druhé zhodnotit příliv zahraničního kapitálu s důrazem na jeho strukturu, a to jak z pohledu teritoriálního, tak z pohledu odvětvového. Na konec je uvedena analýza dopadů PZI v aplikaci na Moravskoslezský region....

  3. Effect of A-TIG Welding Process on the Weld Attributes of Type 304LN and 316LN Stainless Steels

    Science.gov (United States)

    Vasudevan, M.

    2017-03-01

    The specific activated flux has been developed for enhancing the penetration performance of TIG welding process for autogenous welding of type 304LN and 316LN stainless steels through systematic study. Initially single-component fluxes were used to study their effect on depth of penetration and tensile properties. Then multi-component activated flux was developed which was found to produce a significant increase in penetration of 10-12 mm in single-pass TIG welding of type 304LN and 316LN stainless steels. The significant improvement in penetration achieved using the activated flux developed in the present work has been attributed to the constriction of the arc and as well as reversal of Marangoni flow in the molten weld pool. The use of activated flux has been found to overcome the variable weld penetration observed in 316LN stainless steel with welds compared to that of the welds produced by conventional TIG welding on the contrary the transverse strength properties of the 304LN and 316LN stainless steel welds produced by A-TIG welding exceeded the minimum specified strength values of the base metals. Improvement in toughness values were observed in 316LN stainless steel produced by A-TIG welding due to refinement in the weld microstructure in the region close to the weld center. Thus, activated flux developed in the present work has greater potential for use during the TIG welding of structural components made of type 304LN and 316LN stainless steels.

  4. Effect of A-TIG Welding Process on the Weld Attributes of Type 304LN and 316LN Stainless Steels

    Science.gov (United States)

    Vasudevan, M.

    2017-02-01

    The specific activated flux has been developed for enhancing the penetration performance of TIG welding process for autogenous welding of type 304LN and 316LN stainless steels through systematic study. Initially single-component fluxes were used to study their effect on depth of penetration and tensile properties. Then multi-component activated flux was developed which was found to produce a significant increase in penetration of 10-12 mm in single-pass TIG welding of type 304LN and 316LN stainless steels. The significant improvement in penetration achieved using the activated flux developed in the present work has been attributed to the constriction of the arc and as well as reversal of Marangoni flow in the molten weld pool. The use of activated flux has been found to overcome the variable weld penetration observed in 316LN stainless steel with welds compared to that of the welds produced by conventional TIG welding on the contrary the transverse strength properties of the 304LN and 316LN stainless steel welds produced by A-TIG welding exceeded the minimum specified strength values of the base metals. Improvement in toughness values were observed in 316LN stainless steel produced by A-TIG welding due to refinement in the weld microstructure in the region close to the weld center. Thus, activated flux developed in the present work has greater potential for use during the TIG welding of structural components made of type 304LN and 316LN stainless steels.

  5. Synthesis, structure, magnetism, and optical properties of theordered mixed-lanthanide sulfides gamma-LnLn'S3 (Ln=La, Ce; Ln'=Er, Tm,Yb)

    Energy Technology Data Exchange (ETDEWEB)

    Jin, G.B.; Choi, E.S.; Guertin, R.P.; Brooks, J.S.; Bray, T.H.; Booth, C.H.; Albrecht-Schmitt, T.E.

    2006-12-12

    {gamma}-LnLn{prime}S{sub 3} (Ln = La, Ce; Ln{prime} = Er, Tm, Yb) have been prepared as dark red to black single crystals by the reaction of the respective lanthanides with sulfur in a Sb{sub 2}S{sub 3} flux at 1000 C. This isotypic series of compounds adopts a layered structure that consists of the smaller lanthanides (Er, Tm, and Yb) bound by sulfide in six- and seven-coordinate environments that are connected together by the larger lanthanides (La and Ce) in eight- and nine-coordinate environments. The layers can be broken down into three distinct one-dimensional substructures containing three crystallographically unique Ln{prime} centers. The first of these is constructed from one-dimensional chains of edge-sharing [Ln{prime}S{sub 7}] monocapped trigonal prisms that are joined to equivalent chains via edge-sharing to yield ribbons. There are parallel chains of [Ln{prime}S{sub 6}] distorted octahedra that are linked to the first ribbons through corner-sharing. These latter units also share corners with a one-dimensional ribbon composed of parallel chains of [Ln{prime}S{sub 6}] polyhedra that edge-share both in the direction of chain propagation and with adjacent identical chains. Magnetic susceptibility measurements show Curie-Weiss behavior from 2 to 300 K with antiferromagnetic coupling, and no evidence for magnetic ordering. The {theta}{sub p} values range from -0.4 to -37.5 K, and spin-frustration may be indicated for the Yb-containing compounds. All compounds show magnetic moments substantially reduced from those calculated for the free ions. The optical band gaps for {gamma}-LaLn{prime}S{sub 3} (Ln{prime} = Er, Tm, Yb) are approximately 1.6 eV, whereas {gamma}-CeLn{prime}S{sub 3} (Ln{prime} = Er, Tm, Yb) are approximately 1.3 eV.

  6. 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.

  7. The formation of the complex manganites LnSr{sub 2}Mn{sub 2}O{sub 7} (Ln = La, Nd, Gd)

    Energy Technology Data Exchange (ETDEWEB)

    Missyul, A.B., E-mail: lab2193@gmail.com [Department of Chemistry, Saint-Petersburg State University, Universitetsky pr., 26, 198504 St.-Petersburg (Russian Federation); Zvereva, I.A. [Department of Chemistry, Saint-Petersburg State University, Universitetsky pr., 26, 198504 St.-Petersburg (Russian Federation); Palstra, T.T.M. [Solid State Chemistry Laboratory, Zernike Institute for Advanced Materials, University of Groningen, 9747AG Groningen (Netherlands)

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► Formation of the LnSr{sub 2}Mn{sub 2}O{sub 7} phases proceeds according to two different pathways. ► Cationic composition of the obtained phase depends on the formation pathway. ► Step-by-step synthesis allows obtaining single-phase material. ► Structure and magnetic properties of the single-phase NdSr{sub 2}Mn{sub 2}O{sub 7} were investigated. -- Abstract: The process of formation of the Ruddlesden–Popper phases LnSr{sub 2}Mn{sub 2}O{sub 7} (Ln = La, Nd, Gd) was investigated by means of X-ray diffraction, thermal analysis and microprobe analysis. Two parallel pathways were found for the reaction. The first one includes the formation of the intermediate K{sub 2}NiF{sub 4}-type compound by interaction of Sr{sub 7}Mn{sub 4}O{sub 15} and perovskite-type solid solution (Ln,Sr)MnO{sub 3}, while in the second one the K{sub 2}NiF{sub 4}-type intermediate is formed during the reaction of the same perovskite-type solid solution with the corresponding rare earth oxide. This result gives an explanation for the formation of two phases with slightly different cationic compositions. The kinetics of the reaction was investigated for both mechanisms resulting in determination of their relative contribution to the final composition. Pure NdSr{sub 2}Mn{sub 2}O{sub 7} was obtained using a step-by-step process according to the first mechanism, and the magnetic properties of this phase were investigated.

  8. 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.

  9. The effect of lanthanides on color properties of the (Bi2O30.7(Ln2O30.3 compounds

    Directory of Open Access Journals (Sweden)

    Šulcová P.

    2008-01-01

    Full Text Available (Bi2O30.7(Ln2O30,3 solid solutions were synthesized as new inorganic yellow and orange pigments and their color properties have been investigated as possible ecological materials. The pigments were prepared by the solid state reaction of mixed oxides (Bi2O30.7(Ln2O30.3 of various rare earth cations (Ln = Eu, Gd, Tm, Yb and Lu. All the synthesized pigment samples were found to have color coordinates, low a* and high b* and exhibit the color from pale light yellow to orange. Reflectance spectra of the samples show high reflectance percentage in the 600 - 700 nm range. Characterization of the (Bi2O30.7(Ln2O30,3 solid solutions suggests that they have a potential to be alternative yellow colorants for paints, inks, plastics, and ceramics.

  10. 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.

  11. The formation of the complex manganites LnSr(2)Mn(2)O(7) (Ln = La, Nd, Gd)

    NARCIS (Netherlands)

    Missyul, A. B.; Zvereva, I. A.; Palstra, T. T. M.

    2012-01-01

    The process of formation of the Ruddlesden-Popper phases LnSr(2)Mn(2)O(7) (Ln = La, Nd, Gd) was investigated by means of X-ray diffraction, thermal analysis and microprobe analysis. Two parallel pathways were found for the reaction. The first one includes the formation of the intermediate K2NiF4-typ

  12. A density functional investigation on the electronic and magnetic properties of LnSi (Ln= La-Lu) Diatom

    Indian Academy of Sciences (India)

    Zhao Run-Ning; Chen Rui; Yuan Yan-Hong; Gu Fan; Han Ju-Guang

    2016-03-01

    Bond lengths, vibrational frequencies, electron affinities, magnetic properties, and ionization potentials of the neutral and charged LnSi (Ln=La-Lu) diatom were studied by using the density functional method with relativistic effect being taken into account. Ground state was assigned for each species. The calculated natural populations of LnSi (Ln=La-Lu) exhibit that the charges are transferred mainly from 6s2 to 5d,and most of 4f subshell in LnSi is inert without involving chemical bonding. The calculated highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gaps show that the HOMO-LUMOgaps are increased and exhibit oscillating behavior from LaSi to LuSi.Interestingly, total magnetic properties of LnSi (Ln=La-Lu)diatoms depend on the localized 4f electrons which generate the magnetic moment of LnSi diatoms; additionally, the magnetic moment of EuSi is 11 μB, which is the highest one. Comparisons with the available experimental and theoretical values are made and a good agreement is reached.

  13. Thermoelectric properties of molybdenum oxides LnMo(8)O(14) (Ln = La, Ce, Pr, Nd and Sm)

    DEFF Research Database (Denmark)

    Xu, Jianxiao Jackie; Sonne, Monica; Pryds, Nini

    2010-01-01

    The series LnMo8O14 (Ln = La, Ce, Pr, Nd and Sm) containing bicapped Mo8 clusters was synthesized via solid state reaction at 1673 K. Oxides of this type were reported to be narrow gap semiconductors. Our Seebeck coefficient measurements show that some of these reduced molybdenum oxides exhibit...

  14. The luminescence of doped and undoped BaLn2(MoO4)4 (Ln = La,Gd)

    NARCIS (Netherlands)

    Keller, R.C.A.; Blasse, G.; Lindholm, T.; Leskela, M.

    1988-01-01

    The luminescence of nominally pure BaLn2(MoO4)4 (Ln = La,Gd) is reported. Below 300 K molybdate emission is observed. The following activators were investigated: Eu3+, Tb3+, Pb2+ and Bi3+. The two lanthanide ions show their characteristic emission, the two s2 configuration ions give an emission in w

  15. Molybdate templated assembly of Ln12Mo4-type clusters (Ln = Sm, Eu, Gd) containing a truncated tetrahedron core.

    Science.gov (United States)

    Zheng, Yong; Zhang, Qian-Chong; Long, La-Sheng; Huang, Rong-Bin; Müller, Achim; Schnack, Jürgen; Zheng, Lan-Sun; Zheng, Zhiping

    2013-01-01

    Three heterometallic cluster complexes {Ln(12)Mo(4)} featuring an Ln(12) core of a distorted truncated tetrahedron were synthesized with the assistance of four MoO(4)(2-) anions as ancillary ligands. Magnetic studies of the {Gd(12)Mo(4)} cluster revealed a large magnetocaloric effect due to the presence of the large number of weakly coupled Gd(III) ions.

  16. 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

  17. Syntheses, Structure, Magnetism, and Optical Properties of the Interlanthanide Sulfides delta-Ln2-xLuxS3 (Ln = Ce, Pr, Nd)

    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

    {delta}-Ln{sub 2-x}LuxS{sub 3} (Ln = Ce, Pr, Nd; x = 0.67-0.71) compounds have been synthesized through the reaction of elemental rare earth metals and S using Sb{sub 2}S{sub 3} flux at 1000 C. These compounds are isotypic with CeTmS{sub 3}, which has a complex three-dimensional structure. It includes four larger Ln{sup 3+} sites in eight- and nine-coordinate environments, two disordered seven-coordinate Ln{sup 3+}/Lu{sup 3+} positions, and two six-coordinate Lu{sup 3+} ions. The structure is constructed from one-dimensional chains of LnSn (n = 6-9) polyhedra that extend along the b axis. These polyhedra share faces or edges with two neighbors within the chains, while in the [ac] plane they share edges and corners with other chains. Least square refinements gave rise to the formulas of {delta}-Ce{sub 1.30}Lu{sub 0.70}S{sub 3}, {delta}-Pr{sub 1.29}Lu{sub 0.71}S{sub 3} and {delta}-Nd{sub 1.33}Lu{sub 0.67}S{sub 3}, which are consistent with the EDX analysis and magnetic susceptibility data. {delta}-Ln{sub 2-x}LuxS{sub 3} (Ln = Ce, Pr, Nd; x = 0.67-0.71) show no evidence of magnetic ordering down to 5 K. Optical properties measurements show that the band gaps for {delta}-Ce{sub 1.30}Lu{sub 0.70}S{sub 3}, {delta}-Pr{sub 1.29}Lu{sub 0.71}S{sub 3}, and {delta}-Nd{sub 1.33}Lu{sub 0.67}S{sub 3} are 1.25 eV, 1.38 eV, and 1.50 eV, respectively. Crystallographic data: {delta}-Ce{sub 1.30}Lu{sub 0.70}S{sub 3}, monoclinic, space group P2{sub 1}/m, a = 11.0186(7), b = 3.9796(3), c = 21.6562(15) {angstrom}, {beta} = 101.6860(10), V = 929.93(11), Z = 8; {delta}-Pr{sub 1.29}Lu{sub 0.71}S{sub 3}, monoclinic, space group P2{sub 1}/m, a = 10.9623(10), b = 3.9497(4), c = 21.5165(19) {angstrom}, {beta} = 101.579(2), V = 912.66(15), Z = 8; {delta}-Nd{sub 1.33}Lu{sub 0.67}S{sub 3}, monoclinic, space group P2{sub 1}/m, a = 10.9553(7), b = 3.9419(3), c = 21.4920(15) {angstrom}, {beta} = 101.5080(10), V = 909.47(11), Z = 8.

  18. A phase transfer assisted solvo-thermal strategy for the synthesis of REF₃ and Ln³⁺-doped REF3 nano-/microcrystals.

    Science.gov (United States)

    Zhao, Junmei; Zhu, Menghao; Mu, Linqing; Yang, Zhenzhong; Wang, Li; Gu, Lin; Hu, Yong-Sheng; Dai, Sheng; Liu, Huizhou

    2014-12-15

    Monodisperse orthorhombic-phase rare earth fluorides nano-/microcrystals with a special shape of disk-stacked cylinder have been synthesized via a facile phase transfer assisted solvo-thermal route, where an acid-base-coupled extractant has been employed to transfer hydrofluoric acid into an oil phase as a fluoride source. The synthetic parameters have been optimized and a possible formation mechanism has also been proposed. More importantly, the adopted acid-base-coupled extractant in this route can be recycled. Surveying all of the lanthanides from La to Lu, most of the heavy rare earths, such as Tb, Dy, Ho, Er, Tm and Yb, can form LnF3 nanocrystals with the similar morphologies. Furthermore, Ln(3+)-doped YF3 (Ln=Tb, Yb/Er) nanocrystals have also been synthesized, and their down-conversion and up-conversion (980 nm) luminescent properties were examined. The current approach could be extended to synthesize other metal fluorides nanoparticles.

  19. Phase Behavior of Rare Earth Manganites

    Institute of Scientific and Technical Information of China (English)

    Naoki Kamegashira; Hiromi Nakano; Gang Chen; Jian Meng

    2004-01-01

    Among complex oxides containing rare earth and manganese BaLn2Mn2O7 (Ln=rare earth) with the layered perovskite type and Ln2(Mn, M)O7 with pyrochlore-related structure were studied since these compounds show many kinds of phases and unique phase transitions. In BaLn2Mn2O7 there appear many phases, depending on the synthetic conditions for each rare earth. The tetragonal phase of so-called Ruddlesden-Popper type is the fundamental structure and many kinds of deformed modification of this structure are obtained. For BaEu2Mn2O7 at least five phases have been identified from the results of X-ray diffraction analysis with the space group P42/mnm, Fmmm, Immm and A2/m in addition to the fundamental tetragonal I4/mmm phase. In the pyrochlore-related type compounds, Ln2Mn2-xMxO7 (M=Ta, Nb, W etc), there also appear several phases with different crystal structures. With regard to every rare earth, Ln2MnTaO7 phase is stable only for excess Ta and can be obtained under high oxygen partial pressure process. This group has trigonal structure with zirkelite type (P3121 space group). On the other hand Ln2Mn2/3Nb4/3O7 phase has monoclinic (C2/c space group) and zirconolite type structure. All of these structural models have the fundamental structure based on HTB (hexagonal tungsten bronze) layers formed by the arrangement of oxygen octahedra.

  20. Heat capacity, entropy of Ln2(MoO4)3 (Ln = La, Sm, and Gd), and the high-temperature enthalpy of Ln2(MoO4)3 (Ln = Eu, Dy, and Ho)

    Science.gov (United States)

    Lazarev, V. M.; Suponitskiy, Y. L.; Liashenko, S. E.

    2016-05-01

    The low-temperature heat capacity of Ln2(MoO4)3 (Ln = La, Sm, and Gd) is investigated by means of adiabatic calorimetry within the range of 60-300 K. The temperature dependences of the heat capacity are found and the values of the standard entropy are calculated, based on extrapolations to 0 K. Characteristic temperatures for molybdates are determined from the results of IR spectroscopic studies. The high-temperature enthalpy of Ln2(MoO4)3 (Ln = Eu, Dy, and Ho) is measured via high-temperature microcalorimetry, and the temperature dependence of heat capacity is calculated in the range of 298-1000 K. Since samarium and gadolinium molybdates are of the same structural type as terbium molybdate, we can estimate the anomaly of the heat capacity in the low-temperature region using the data for terbium molybdate and find the entropy of samarium and gadolinium molybdates.

  1. Solvochemical synthesis and crystal structure of the fluoride-derivatized early lanthanoid(III) ortho-oxidomolybdates(VI) LnF[MoO{sub 4}] (Ln = Ce-Nd)

    Energy Technology Data Exchange (ETDEWEB)

    Schustereit, Tanja; Schleid, Thomas; Hartenbach, Ingo [Institute for Inorganic Chemistry, University of Stuttgart (Germany)

    2014-10-15

    The development of a new solvochemical synthesis route resulted in single crystals of lanthanoid(III) fluoride oxidomolybdates(VI) with the formula LnF[MoO{sub 4}] for the early lanthanoids (Ln = Ce-Nd); to date, these compounds could not be obtained by solid-state reactions. The preparation strategy comprises the dropwise combination of an alkaline aqueous solution containing molybdenum trioxide, sodium hydroxide and sodium fluoride with an acidic aqueous solution of the lanthanoid(III) nitrate. After the purification of the obtained gel, the noncrystalline product has to be dried at 120 C and converted into a crystalline phase by a final thermal treatment for 24 h at 850 C in evacuated silica ampoules. The crystal structure of the lanthanoid(III) fluoride oxidomolybdates(VI) with formula LnF[MoO{sub 4}] (Ln = Ce-Nd) is not isotypic to those for the smaller rare-earth metals. The title compounds crystallize monoclinically in the space group P2{sub 1}/n (a = 703-694, b = 660-653, c = 939-933 pm and β ∼ 106 ) with four formula units per unit cell. The structure contains crystallographically unique Ln{sup 3+} cations, which are surrounded by two F{sup -} and six O{sup 2-} anions to form distorted bicapped trigonal prisms (CN = 8). These polyhedra are fused together by two common edges (e) consisting of two oxide anions to form {sub ∞}{sup 1}{[LnFO"e_4_/_2O"t_2_/_1]"6"-} strands, which are finally condensed through shared fluoride vertices (v) to build up a three-dimensional {sub ∞}{sup 3}{[LnF"v_2_/_2O"e_4_/_2O"t_2_/_1]"6"-} network that still contains terminal (t) oxygen atoms. The Mo{sup 6+} cations reside in the tetrahedral voids of the aforementioned arrangement. This is the fundamental difference compared to the structures of the representatives with the smaller lanthanoids, in which the Mo{sup 6+} cations interconnect anionic {sub ∞}{sup 2}{[LnF"e_2_/_2O"e_4_/_2O"t_2_/_1]"6"-} layers to achieve their tetrahedral oxygen coordination spheres. Vibrational

  2. Hydrothermal Synthesis of RbLn2F7 and VUV Spectroscopy of RbLn2F7:Eu3+(Ln=Gd, Y)

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    RbLn2F7 (Ln=Gd, Y, Er, Yb and Lu), crystallized in the hexagonal RbEr2F7 structure type, is synthesized by a hydrothermal method. The excitation spectra of Eu3+-doped RbGd(Y)2F7 suggest that the oxygen content is very low in the samples obtained by hydrothermal synthesis. Only the f-f transitions of Gd3+ ions are observed in the excitation spectrum of RbGd2F7:Eu3+ (0.5mol%), while those of Eu3+ ions do not appear. When the Gd3+ ions are excited, the absorbed energy is transferred efficiently from Gd3+ to Eu3+. The spectra show that the doped Eu3+ ions are located in non-centrosymmetric sites in hexagonal RbLn2F7.

  3. Neutral binuclear rare-earth metal complexes with four μ₂-bridging hydrides.

    Science.gov (United States)

    Rong, Weifeng; He, Dongliang; Wang, Meiyan; Mou, Zehuai; Cheng, Jianhua; Yao, Changguang; Li, Shihui; Trifonov, Alexander A; Lyubov, Dmitrii M; Cui, Dongmei

    2015-03-25

    The first neutral rare-earth metal dinuclear dihydrido complexes [(NPNPN)LnH2]2 (2-Ln; Ln = Y, Lu; NPNPN: N[Ph2PNC6H3((i)Pr)2]2) bearing μ2-bridging hydride ligands have been synthesized. In the presence of THF, 2-Y undergoes intramolecular activation of the sp(2) C-H bond to form dinuclear aryl-hydride complex 3-Y containing three μ2-bridging hydride ligands.

  4. Defect Scheelite-Type Lanthanoid(III Ortho-Oxomolybdates(VI Ln0.667[MoO4] (Ln = Ce, Pr, Nd, and Sm and Their Relationship to Zircon and the NaTl-Type Structure

    Directory of Open Access Journals (Sweden)

    Ingo Hartenbach

    2011-12-01

    Full Text Available The rare-earth metal(III ortho-oxomolybdates with the formula Ln0.667[MoO4] (Ln = Ce, Pr, Nd, and Sm and defect scheelite-type structure crystallize in the tetragonal space group I41/a (a = 533–525, c = 1183–1158 pm with four formula units per unit cell. The Ln3+ cations at Wyckoff position 4b exhibit a coordination sphere of eight oxygen atoms in the shape of a trigonal dodecahedron. The same site symmetry (.. is observed for the tetrahedral oxomolybdate(VI entities [MoO4]2–, since their central Mo6+ cation is situated at the 4a position. Due to this equal site multiplicity, the lanthanoid(III cations have to be statistically under-occupied to maintain electroneutrality, thus a defect scheelite structure emerges. The partial structure of both the Ln3+ cations and the [MoO4]2– anions (if shrunk to their centers of gravity can be best described as distorted diamond-like arrangements. Therefore, these two interpenetrating partial structures exhibit a similar setup as found in the zircon-type as well as in the NaTl-type structure.

  5. Cationic ordering and role of the B-site lanthanide(III) and molybdenum(V) cations on the structure and magnetism of double perovskites Sr{sub 2}LnMoO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Pinacca, R.M.; Larrégola, S.A.; López, C.A. [INTEQUI-Área de Química General e Inorgánica “Dr. G.F. Puelles”, Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, 5700 San Luis (Argentina); Pedregosa, J.C., E-mail: jpedreg@gmail.com [INTEQUI-Área de Química General e Inorgánica “Dr. G.F. Puelles”, Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, 5700 San Luis (Argentina); Pomjakushin, Vladimir [Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Sánchez, R.D. [Centro Atómico Bariloche, Comisión Nacional de Energía Atómica and Instituto Balseiro, Universidad Nacional de Cuyo, 8400 S.C. de Bariloche, Río Negro (Argentina); Alonso, J.A. [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid (Spain)

    2015-06-15

    Highlights: • Five new double perovskites of formula Sr{sub 2}LnMoO{sub 6} were synthesized. • All the samples crystallize in the monoclinic P2{sub 1}/n space group. • Strong reducing conditions were used in order to stabilized Mo(V) cations. • A complete ordering between the rare earth and molybdenum ions was observed. • Magnetism agrees with the crystal distortions observed from Rietveld analysis. - Abstract: We describe the preparation, crystal structure determination and magnetic properties of a new series of ordered double perovskite oxides Sr{sub 2}LnMoO{sub 6} (Ln = Eu, Gd, Dy, Ho, Er, Yb) with Mo{sup 5+} and Ln{sup 3+} electronic configurations. These compounds have been obtained by solid state reaction under reducing conditions in order to stabilize Mo{sup 5+} cations. Structural characterization by XRPD and NPD was performed when Ln = Ho, Er, Yb and just XRPD for absorbing Ln = Eu, Gd, Dy. At room temperature, an excellent Rietveld fit was obtained for all the samples in a monoclinic symmetry, space group P2{sub 1}/n, with long-range ordering of Ln and Mo atoms. Magnetic susceptibility measurements show that some of these materials present magnetic ordering below 25 K and the determined effective magnetic moments are consistent with those expected for the pair Ln{sup 3+}–Mo{sup 5+}. All the phases have negative values​​ of the Weiss temperature indicating dominance of antiferromagnetic interactions.

  6. Theoretical aspects of photonic band gap in 1D nano structure of LN: MgLN periodic layer

    Energy Technology Data Exchange (ETDEWEB)

    Sisodia, Namita, E-mail: namitasisodiya@gmail.com [Department of Physics, Holkar Science Collage, Indore-452017 (India)

    2015-06-24

    By using the transfer matrix method, we have analyzed the photonic band gap properties in a periodic layer of LN:MgLN medium. The Width of alternate layers of LN and MgLN is in the range of hundred nanometers. The birefringent and ferroelectric properties of the medium (i.e ordinary, extraordinary refractive indices and electric dipole moment) is given due considerations in the formulation of photonic band gap. Effect of electronic transition dipole moment of the medium on photonic band gap is also taken into account. We find that photonic band gap can be modified by the variation in the ratio of the width of two medium. We explain our findings by obtaining numerical values and the effect on the photonic band gap due to variation in the ratio of alternate medium is shown graphically.

  7. Linear analysis on the stability of lanthanide vapor complexes LnAl3Cli2(Ln = La to Lu)

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The reactions LnCl3 (s) + (3/2)Al2Cl6 (g) = LnAl3Cl12 (g) for Ln = La to Lu were studied by quenching experi-ments in roughly the same temperature and pressure ranges (588-851 K and 0.01-0.22 MPa). Stability constants Kθ oflanthanide complexes LnAl3Cl12 were calculated from the measurements. The values of lg Kθ change linearly with theionpotential (Z+/r) of lanthanide(Ⅲ) from La to Gd and from Tb to Lu, respectively, indicating the Gd break. There exist in-clined W effect between lg Kθ and the total angular momentum L of lanthanide(Ⅲ). And hereby lanthanide elements aredivided into four segments, La-Nd, Pm-Gd, Tb-Ho, and Er-Lu. In each segment, the linearity is maintained.

  8. Decanuclear Ln10 Wheels and Vertex-Shared Spirocyclic Ln5 Cores: Synthesis, Structure, SMM Behavior, and MCE Properties.

    Science.gov (United States)

    Das, Sourav; Dey, Atanu; Kundu, Subrata; Biswas, Sourav; Narayanan, Ramakirushnan Suriya; Titos-Padilla, Silvia; Lorusso, Giulia; Evangelisti, Marco; Colacio, Enrique; Chandrasekhar, Vadapalli

    2015-11-16

    The reaction of a Schiff base ligand (LH3) with lanthanide salts, pivalic acid and triethylamine in 1:1:1:3 and 4:5:8:20 stoichiometric ratios results in the formation of decanuclear Ln10 (Ln = Dy (1), Tb (2), and Gd (3)) and pentanuclear Ln5 complexes (Ln = Gd (4), Tb (5), and Dy (6)), respectively. The formation of Ln10 and Ln5 complexes are fully governed by the stoichiometry of the reagents used. Detailed magnetic studies on these complexes (1-6) have been carried out. Complex 1 shows a SMM behavior with an effective energy barrier for the reversal of the magnetization (Ueff) = 16.12(8) K and relaxation time (τo) = 3.3×10(-5) s under 4000 Oe direct current (dc) field. Complex 6 shows the frequency dependent maxima in the out-of-phase signal under zero dc field, without achieving maxima above 2 K. Complexes 3 and 4 show a large magnetocaloric effect with the following characteristic values: -ΔSm = 26.6 J kg(-1) K(-1) at T = 2.2 K for 3 and -ΔSm = 27.1 J kg(-1) K(-1) at T = 2.4 K for 4, both for an applied field change of 7 T.

  9. Trivalent lanthanide compounds with fluorinated thiolate ligands: Ln-F dative interactions vary with Ln and solvent.

    Science.gov (United States)

    Melman, Jonathan H; Rohde, Christa; Emge, Thomas J; Brennan, John G

    2002-01-14

    The fluorinated tris-thiolate compounds Ln(SC(6)F(5))(3) can be isolated as THF, pyridine, or DME coordination complexes. In THF, the larger Ce forms dimeric [(THF)(3)Ce(SC(6)F(5))(3)](2) (1) with bridging thiolate ligands, while the smaller lanthanides (Ln = Ho (2), Er (3)) form monometallic (THF)(3)Ln(SC(6)F(5))(3) compounds. There is a tendency for fluoride to coordinate to Ln throughout the lanthanide series (Ce-Er). The cerium compound 1 contains a pair of bridging thiolates connecting two eight-coordinate Ce(III) ions. Of the two terminal thiolates, only one exhibits a distinct Ce-F bond. In contrast, the Ho derivative (THF)(3)Ho(SC(6)F(5))(3) is a molecular compound in the solid state, with two monodentate thiolates and one thiolate that again coordinates through both S and F atoms. Incorporation of a stronger Lewis base reduces but does not necessarily eliminate the tendency to form Ln-F bonds. Structural characterization of the eight-coordinate (pyridine)(4)Sm(SC(6)F(5))(3) (4) reveals a single, clearly defined Ln-F interaction, while in (pyridine)(4)Yb(SC(6)F(5))(3) (5) there are no Yb-F bonds. In the structure of (DME)(2)Er(SC(6)F(5))(3) (6) the DME ligands completely displace F from the Er coordination sphere.

  10. A facile single-step procedure for the synthesis of luminescent Ln{sup 3+}:YVO{sub 4} (Ln = Eu or Er + Yb)-silica nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Ocana, Manuel, E-mail: mjurado@icmse.csic.es [Instituto de Ciencia de Materiales de Sevilla, CSIC-US, Americo Vespucio 49, 41092 Isla de la Cartuja, Sevilla (Spain); Cantelar, Eugenio; Cusso, Fernando [Depto. Fisica de Materiales, C-IV, Universidad Autonoma de Madrid (Spain)

    2011-01-01

    A simple and single-step method for the production of Ln-doped YVO{sub 4} nanocrystals and their simultaneous encapsulation in a silica network based on the pyrolysis of liquid aerosols at 800 deg. C is reported. The procedure is illustrated for Yb,Er:YVO{sub 4}-silica nanocomposites consisting of spherical particles, which present up-converted green luminescence after IR excitation whose efficiency increased on annealing up to 1000 deg. C due to the release of impurities (adsorbed water, and residual anions). XPS spectroscopy and TEM observations revealed that the surface of the composite particles was enriched in silica, which would facilitate their functionalisation required to use them in biological applications. The procedure can also be used to prepare other rare earth doped systems as illustrated for the case of Eu-doped YVO{sub 4}/silica having down-converted red luminescence.

  11. Laser spectroscopy of rare earth ions in lead borate glasses and transparent glass-ceramics

    Science.gov (United States)

    Pisarski, W. A.; Grobelny, Ł.; Pisarska, J.; Lisiecki, R.; Dominiak-Dzik, G.; Ryba-Romanowski, W.

    2010-03-01

    Rare earth doped lead borate glasses and transparent glass-ceramics have been studied using optical spectroscopy. Based on the absorption, emission and its decay and the Judd-Ofelt calculations, several radiative and laser parameters for Ln 3+ ( Ln = Pr, Nd, Eu, Dy, Er, Tm) were evaluated. The large values of luminescence lifetime, quantum efficiency of excited state and room temperature peak stimulated emission cross-section suggest efficient laser transitions of Ln 3+ ions in lead borate glasses. The obtained results indicate that lead borate glasses and glass-ceramics containing Ln 3+ ions are promising host matrices for solid-state laser applications.

  12. Lanthanide mixed-ligand complexes of the [Ln(CAPh)3(Phen)] and [LaxEu1-x(CAPh)3(Phen)] (CAPh = carbacylamidophosphate) type. A comparative study of their spectral properties.

    Science.gov (United States)

    Litsis, Olena O; Ovchynnikov, Vladimir A; Scherbatskii, Vasyl P; Nedilko, Sergiy G; Sliva, Tatiana Yu; Dyakonenko, Viktoriya V; Shishkin, Oleg V; Davydov, Valentine I; Gawryszewska, Paula; Amirkhanov, Vladimir M

    2015-09-21

    A series of complexes Ln(Pip)3(Phen) (Ln(iii) = La, Ce-Nd, Sm-Lu, Y; HPip (CAPh type ligand) = 2,2,2-trichloro-N-(dipiperidin-1-yl-phosphoryl)acetamide, Phen = 1,10-phenanthroline) has been synthesized. The lanthanum(iii) doped europium(iii) complexes ([LaxEu1-x(Pip)3(Phen)], x = 0.99, 0.95, 0.50) have been obtained by the co-crystallization method. The complexes have been characterized by means of X-ray diffraction, IR, (1)H and (31)P-NMR and absorption spectroscopy. Emission and excitation luminescence spectra were recorded at 295 and 77 K. The lifetime values (τ) for the emission of all europium complexes were determined. The (5)D0 luminescence quantum efficiency is 73-89%. The symmetries of the nearest europium surrounding in pure and doped complexes were evaluated from the Stark splitting of (5)D0-(7)FJ transitions. Crystal structures of [Ln(Pip)3(Phen)] (Ln = Nd (1), Eu (2) and Tb (3)) have been determined. Lattice parameters of the [Ln(Pip)3(Phen)] (Ln = Tb, Yb) and the doped [LaxEu1-x(Pip)3(Phen)] (x = 0.99, 0.95, 0.50) complexes have been measured. The presence of four polymorphs within a number of rare earth elements has been estimated: two in triclinic (Ln1 = La, Nd; Ln2 = Eu), one in the monoclinic (Ln3 = Tb) and one in the rhombic (Ln4 = Tb, Yb) symmetry. Complex 3 can be obtained in two crystal modifications: monoclinic and orthorhombic ones.

  13. Protonic conduction in rare earth orthophosphates with the monazite structure

    Energy Technology Data Exchange (ETDEWEB)

    Kitamura, N.; Amezawa, K.; Yamamoto, N. [Graduate School of Human and Environmental Studies, Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan); Tomii, Y. [Graduate School of Energy Science, Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan)

    2003-09-01

    Electrical conduction in rare earth orthophosphates, LnPO{sub 4} (Ln=La, Pr, Nd and Sm), with the monazite structure (P2{sub 1}/n) was investigated by using conductivity measurements at 500-925 C. From the conductivities of undoped and 1 mol% Sr-doped LnPO{sub 4} under wet (H{sub 2}O and D{sub 2}O) and dry atmospheres, it was found that LnPO{sub 4} began to conduct protons under wet atmosphere by substituting Sr for Ln. The conductivity behavior of 1 mol% Sr-doped LnPO{sub 4} versus p(H{sub 2}O) and p(O{sub 2}) was discussed in terms of the defect equilibria. It was concluded that protonic conduction was dominant in the materials though electron holes contributed slightly to the total conductivity as temperature increased. All the 1 mol% Sr-doped LnPO{sub 4} investigated in this study exhibited similar electrical conduction regardless of rare earth element used.

  14. Synthesis and photoluminescent properties of doped ternary Eu_(1-x)Ln_x(NPPD)_3·DPQ complexes

    Institute of Scientific and Technical Information of China (English)

    李月琴; 李烨; 徐慧华; 陶弦; 张冬梅; 沈应中

    2010-01-01

    Rare earth (RE) ternary complexes of Eu0.5Ln0.5(NPPD)3·(DPQ) (HNPPD=1-(naphthalen-2-yl)-3-phenylpropane-1,3-dione; DPQ= dipyridobenzoquinone) and Eu1-xLax(NPPD)3·(DPQ) (Ln3+=La3+, Gd3+, Sm3+, Pr3+; x=0.0, 0.1, 0.3, 0.5, 0.7, 0.9) were synthesized by the reaction of RECl3·6H2O with HNPPD and DPQ in stoichiometry. The complexes were characterized with IR, elemental analysis, TGA-DSC and wide-angle X-ray diffraction. The UV-Vis absorption spectra and fluorescence properties of the complexes were also investiga...

  15. 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.

  16. 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.

  17. Serendipitous syntheses of the series Cs 3Ln 7Te 12 (Ln = Sm, Gd, Tb): Compounds with large tunnels

    Science.gov (United States)

    Tougait, Olivier; Noël, Henri; Ibers, James A.

    2001-05-01

    Single crystals of Cs 3Ln 7Te 12 (Ln = Sm, Gd, Tb) have been grown accidentally through the reaction of Ln and Te with a CsCl or Cs 2Te 3 flux at elevated temperatures. The crystal structures have been determined from single crystal X-ray diffraction data. These compounds, which are isostructural with Rb 3Yb 7Se 12, crystallize in space group Pnnm of the orthorhombic system with two molecules in the following cells: Cs 3Sm 7Te 12, a=13.750(6), b=28.332(7), c=4.473(3) Å, T=293 K; Cs 3Gd 7Te 12, a=13.6064(13), b=28.209(3), c=4.4324(4) Å, T=153 K; Cs 3Tb 7Te 12, a=13.5708(16), b=28.116(3), c=4.4147(5) Å, T=153 K.

  18. Microchip Yb:CaLnAlO4 lasers with up to 91% slope efficiency.

    Science.gov (United States)

    Loiko, Pavel; Serres, Josep Maria; Mateos, Xavier; Xu, Xiaodong; Xu, Jun; Jambunathan, Venkatesan; Navratil, Petr; Lucianetti, Antonio; Mocek, Tomas; Zhang, Xuzhao; Griebner, Uwe; Petrov, Valentin; Aguiló, Magdalena; Díaz, Francesc; Major, Arkady

    2017-07-01

    Multi-watt continuous-wave (CW) operation of tetragonal rare-earth calcium aluminate Yb:CaLnAlO4(Ln=Gd,Y)) crystals in plano-plano microchip lasers was demonstrated with an almost quantum-defect-limited slope efficiency. Pumped at 978 nm by an InGaAs laser diode, a 3.4 mm long 8 at. % Yb:CaGdAlO4 laser generated 7.79 W at 1057-1065 nm with a slope efficiency of η=84% (with respect to the absorbed pump power). An even higher η=91% was achieved with a 2.5 mm long 3 at. % Yb:CaYAlO4 laser, from which 5.06 W were extracted at 1048-1056 nm. Both lasers produced linearly polarized output (σ-polarization) with an almost circular diffraction-limited beam (Mx,y2<1.1). The output performance of the developed lasers was modeled, yielding an internal loss coefficient as low as 0.004-0.007  cm(-1). In addition, their spectroscopic properties were revisited.

  19. Highly-efficient multi-watt Yb:CaLnAlO4 microchip lasers

    Science.gov (United States)

    Loiko, Pavel; Serres, Josep Maria; Mateos, Xavier; Xu, Xiaodong; Xu, Jun; Yumashev, Konstantin; Griebner, Uwe; Petrov, Valentin; Aguiló, Magdalena; Díaz, Francesc; Major, Arkady

    2017-02-01

    Tetragonal rare-earth calcium aluminates, CaLnAlO4 where Ln = Gd or Y (CALGO and CALYO, respectively), are attractive laser crystal hosts due to their locally disordered structure and high thermal conductivity. In the present work, we report on highly-efficient power-scalable microchip lasers based on 8 at.% Yb:CALGO and 3 at.% Yb:CALYO crystals grown by the Czochralski method. Pumped by an InGaAs laser diode at 978 nm, the 6 mm-long Yb:CALGO microchip laser generated 7.79 W at 1057-1065 nm with a slope efficiency of η = 84% (with respect to the absorbed pump power) and an optical-to-optical efficiency of ηopt = 49%. The 3 mm-long Yb:CALYO microchip laser generated 5.06 W at 1048-1056 nm corresponding to η = 91% and ηopt = 32%. Both lasers produced linearly polarized output (σ- polarization) with an almost circular beam profile and beam quality factors M2 x,y <1.1. The output performance of the developed lasers was modeled yielding a loss coefficient as low as 0.004-0.007 cm-1. The results indicate that the Yb3+- doped calcium aluminates are very promising candidates for high-peak-power passively Q-switched microchip lasers.

  20. Synthesis, Characterization and Thermal Decomposition of Ln (Me2dtc)3(phen) (Ln=La, Pr, Nd, Sm)

    Institute of Scientific and Technical Information of China (English)

    He Jin; Chen Shanping; Gao Shengli

    2007-01-01

    Four solid complexes of Ln(Me2dtc)3(phen) (Ln=La, Pr, Nd, Sm) were synthesized in anhydrous ethanol by the reaction of lanthanide chloride low hydrate with the mixed ligand of sodium dimethyldithiocarbamate and 1, 10-phenanthroline·H2O (phen·H2O), and characterized by elemental analysis, IR spectroscopy, TG-DTG, and X-ray diffraction analysis. TG-DTG with X-ray powder diffraction showed that these compounds could decompose to lanthanide sulfides at relatively lower temperature, which indicated that the title complexes could be favorable precursors to prepare lanthanide sulfides.

  1. 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.

  2. Synthesis,structure and catalytic activity of complexes [Ln(EDBP)2(DME)Na(DME)3](Ln=Er,Yb,Sm) for ring-opening polymerization of ε-caprolactone

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Discrete ion-pair complexes [Ln(EDBP)2(DME)Na(DME)3] [Ln=Er (1), Yb (2), Sm (3)] have been synthesized by the reaction between sodium salt of 2,2’-ethylidene-bis(4,6-di-tert-butylphenol)(EDBPH2) and Ln(BH4)3·3THF (Ln=Er, Yb, Sm) followed by centrifugation and recrystalization. The complexes were characterized by elemental analysis and FT-IR, and the bonding model of these compounds was confirmed by X-ray single crystal diffraction for complex 1. It was found that four O atoms in two biphenol ligands as well as two O atoms in one ethylene glycol dimethyl ether (DME) molecule connect to the center rare earth metal atom, while sodium exists as counterpart cation to balance the charge. Complexes 1―3 can all be used as single component initiators for the ring-opening polymerization of ε-caprolactone.

  3. Energetic Ionic Liquids Based on Anionic Rare Earth Nitrate Complexes (Preprint)

    Science.gov (United States)

    2008-07-10

    hydrolytically unstable [ bmim ]Ln(SCN)7. [5b] However, the former exist as hydrates and are not stable in the absence of water of hydration and are not typical...ionic liquids. The instability of [ bmim ]Ln(SCN)7 to moisture and air also limits their applications. Since our new rare-earth ionic liquids do not...component in energetic ionic liquids.[7] Rare earth metals coordinate with O-donor ligands more strongly than N-donor ligands,[8] e. g., in [ bmim ]Ln

  4. Influence of lead oxide addition on LnTiTaO6 (Ln = Ce, Pr and Nd) microwave ceramics

    Indian Academy of Sciences (India)

    H Padma Kumar; J K Thomas; Annamma John; Sam Solomon

    2011-02-01

    The effect of PbO addition on the structural, processing and microwave dielectric properties of LnTiTaO6 (Ln = Ce, Pr and Nd) ceramics are reported. Conventional solid state ceramic route was used for the preparation of samples. Phase pure LnTiTaO6 (Ln = Ce, Pr and Nd) ceramics are prepared at a calcination temperature of 1300°C. The samples are sintered at optimized temperatures. Addition of PbO reduces the sintering temperature. The crystal structure of the materials was analysed using X-ray diffraction techniques and the surface morphology of the sintered samples was analysed using scanning electron microscopy. The dielectric constant at microwave frequency range decreases for higher PbO addition for all the samples but the quality factor improves on small PbO addition. The thermal stability of resonant frequency was also improved with PbO addition on all the systems. A number of samples with improved microwave dielectric properties were obtained on all the systems suitable for practical applications.

  5. Crystallographic and spectroscopic characterization of LnFeTeO{sub 6} (Ln = La, Pr, Nd, Sm) materials

    Energy Technology Data Exchange (ETDEWEB)

    Lavat, Araceli E. [Departamento de Ingenieria Quimica, Facultad de Ingenieria, Universidad Nacional del Centro de la Provincia de Buenos Aires, 7400 Olavarria (Argentina); Mercader, Roberto C. [Departamento de Fisica and Instituto IFLP (CONICET), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 1900 La Plata (Argentina); Baran, Enrique J., E-mail: baran@quimica.unlp.edu.a [Centro de Quimica Inorganica (CEQUINOR/CONICET, UNLP), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C. Correo 962, 1900 La Plata (Argentina)

    2010-10-15

    Research highlights: {yields} LnFeTeO{sub 6} (Ln = La, Pr, Nd, Sm) materials belong to a PbSb{sub 2}O{sub 6} superstructure. {yields} IR and Raman spectra are dominated by TeO{sub 6} vibrations. {yields} Te-O bonds are relatively weak.{yields} Fe{sup III}O{sub 6}-polyhedra are scarcely distorted. - Abstract: Four mixed oxides of composition LnFeTeO{sub 6} (with Ln = La, Pr, Nd, Sm), belonging to a superstructure of the PbSb{sub 2}O{sub 6} structural type, have been prepared by solid state reactions and their unit cell parameters determined by X-ray powder diffractometry. The infrared and Raman spectra of these materials were also recorded and briefly discussed, on the basis of a site-symmetry analysis. The {sup 57}Fe-Moessbauer spectra show that the Fe{sup III}O{sub 6} octahedra present in these materials are not greatly distorted.

  6. Hydrothermal synthesis of 4ZnO·B2O3·H2O:Ln(3+) (Ln=Eu, Tb) phosphors: Morphology-tunable and luminescence properties.

    Science.gov (United States)

    Cao, Shiwei; Jiao, Yang; Han, Weifang; Ge, Chunhua; Song, Bo; Wang, Jie; Zhang, Xiangdong

    2017-09-18

    4ZnO·B2O3·H2O:Ln(3+) (Ln=Eu, Tb) phosphors with different morphologies have been successfully synthesized via one-step hydrothermal method through regulating the molar amount of Eu(3+) and Tb(3+). Comprehensive scanning electron microscopy (SEM), X-ray diffraction (XRD) Fourier transform infrared spectrum (FT-IR) and inductively coupled plasma atomic emission spectrometer (ICP-AES) characterizations all confirm that obtained products are 4ZnO·B2O3·H2O:Ln(3+) (Ln=Eu, Tb). The experimental results displayed that the morphology and photoluminescence of compounds is regularly changed with increased the molar amount of rare earth ions. For the Eu(3+)-doped, Tb(3+)-doped and Eu(3+)/Tb(3+) co-doped 4ZnO·B2O3·H2O phosphors of morphologies, the rod-like structures gradually changed to flower-like structures, fine wire-like structure and hybrid structure, respectively. To their photoluminescence, the Eu(3+) shows a red emission (615nm); the Tb(3+) shows a green emission (545nm); for the Eu(3+)/Tb(3+) co-doped 4ZnO·B2O3·H2O phosphors, a combination of blue (5d-4f of Eu(2+)), green ((5)D4-(7)F5 of Tb(3+)) and red ((5)D0-(7)F2 of Eu(3+)) emissions emerges to achieve white emission. In addition, the energy transfer among Eu(3+), Eu(2+) and Tb(3+) ions was also discussed. Copyright © 2017. Published by Elsevier B.V.

  7. Crystal growth, structure, and physical properties of Ln(Cu,Al)12 (Ln = Y, Ce, Pr, Sm, and Yb) and Ln(Cu, Ga)12 (Ln = Y, Gd-Er, and Yb).

    Science.gov (United States)

    Drake, Brenton L; Capan, C; Cho, Jung Young; Nambu, Y; Kuga, K; Xiong, Y M; Karki, A B; Nakatsuji, S; Adams, P W; Young, D P; Chan, Julia Y

    2010-02-17

    Single crystals of Ln(Cu,Al)12 and Ln(Cu,Ga)12 compounds (Ln = Y, Ce-Nd, Sm, Gd-Ho, and Yb for Al and Ln = Y, Gd-Er, Yb for Ga) have been grown by flux-growth methods and characterized by means of single-crystal x-ray diffraction, complemented with microprobe analysis, magnetic susceptibility, resistivity and heat capacity measurements. Ln(Cu,Ga)12 and Ln(Cu,Al)12 of the ThMn12 structure type crystallize in the tetragonal I4/mmm space group with lattice parameters a approximately 8.59 Å and c approximately 5.15 Å and a approximately 8.75 Å and c approximately 5.13 Å for Ga and Al containing compounds, respectively. For aluminium containing compounds, magnetic susceptibility data show Curie-Weiss paramagnetism in the Ce and Pr analogues down to 50 K with no magnetic ordering down to 3 K, whereas the Yb analogue shows a temperature-independent Pauli paramagnetism. Sm(Cu,Al)12 orders antiferromagnetically at T(N)approximately 5 K and interestingly exhibits Curie-Weiss behaviour down to 10 K with no Van Vleck contribution to the susceptibility. Specific heat data show that Ce(Cu,Al)12 is a heavy fermion antiferromagnet with T(N) approximately 2 K and with an electronic specific heat coefficient γ0 as large as 390 mJ K2 mol(-1). In addition, this is the first report of Pr(Cu,Al)12 and Sm(Cu,Al)12 showing an enhanced mass (approximately 80 and 120 mJ K(2) mol(-1)). For Ga containing analogues, magnetic susceptibility data also show the expected Curie-Weiss behaviour from Gd to Er, with the Yb analogue being once again a Pauli paramagnet. The antiferromagnetic transition temperatures range over 12.5, 13.5, 6.7, and 3.4 K for Gd, Tb, Dy, and Er. Metallic behaviour is observed down to 3 K for all Ga and Al analogues. A large positive magnetoresistance up to 150% at 9 T is also observed for Dy(Cu,Ga)12. The structure, magnetic, and transport properties of these compounds will be discussed.

  8. Synthesis, Catalysis of Rare Earth Complexes with Aliphatic Noncyclic Polyether-Amino Acid Schiff Base

    Institute of Scientific and Technical Information of China (English)

    Li Ning; Yao Kemin; Shen Lianfang

    2005-01-01

    Eleven new rare earth complexes with aliphatic Schiff base, condensed from diglycol aldehyde and bis-arginine, were synthesized and characterized. They are confirmed as Ln(H2DAAR)(NO3)3·7H2O (Ln=La, Pr, Nd, Gd), Ln3(H2DAAR)2(NO3)9·5H2O (Ln=Dy, Y) and Ln2(H2DAAR)(NO3)6·3H2O (Ln=La, Nd, Sm, Gd), Ln3(DAAR)(NO3)7·4H2O (Ln=Dy, Yb, Y) respectively under different molar ratios of metal to ligand (DAAR=diglycol aldehyde bis-arginine). The present paper deals with a synthetic method and catalytic properties of obtained complexes. The result shows that proper pH value is important for synthesis of the complexes and compositions of the lighter and the heavier rare earth complexes are different under the same reaction condition. Some new complexes obtained have proved their catalytic activity and 80% conversion with the viscosity-average molecular weight 230,000 for the polymerization of methyl methacrylate (MMA) without addition of any cocatalyst.

  9. Dynamic Recrystallization and Hot Workability of 316LN Stainless Steel

    Directory of Open Access Journals (Sweden)

    Chaoyang Sun

    2016-07-01

    Full Text Available To identify the optimal deformation parameters for 316LN austenitic stainless steel, it is necessary to study the macroscopic deformation and the microstructural evolution behavior simultaneously in order to ascertain the relationship between the two. Isothermal uniaxial compression tests of 316LN were conducted over the temperature range of 950–1150 °C and for the strain rate range of 0.001–10 s−1 using a Gleeble-1500 thermal-mechanical simulator. The microstructural evolution during deformation processes was investigated by studying the constitutive law and dynamic recrystallization behaviors. Dynamic recrystallization volume fraction was introduced to reveal the power dissipation during the microstructural evolution. Processing maps were developed based on the effects of various temperatures, strain rates, and strains, which suggests that power dissipation efficiency increases gradually with increasing temperature and decreasing stain rate. Optimum regimes for the hot deformation of 316LN stainless steel were revealed on conventional hot processing maps and verified effectively through the examination of the microstructure. In addition, the regimes for defects of the product were also interpreted on the conventional hot processing maps. The developed power dissipation efficiency maps allow optimized processing routes to be selected, thus enabling industry producers to effectively control forming variables to enhance practical production process efficiency.

  10. Glass Ceramic Waste Forms for Combined CS+LN+TM Fission Products Waste Streams

    Energy Technology Data Exchange (ETDEWEB)

    Crum, Jarrod V.; Turo, Laura A.; Riley, Brian J.; Tang, Ming; Kossoy, Anna; Sickafus, Kurt E.

    2010-09-23

    In this study, glass ceramics were explored as an alternative waste form for glass, the current baseline, to be used for immobilizing alkaline/alkaline earth + lanthanide (CS+LN) or CS+LN+transition metal (TM) fission-product waste streams generated by a uranium extraction (UREX+) aqueous separations type process. Results from past work on a glass waste form for the combined CS+LN waste streams showed that as waste loading increased, large fractions of crystalline phases precipitated upon slow cooling.[1] The crystalline phases had no noticeable impact on the waste form performance by the 7-day product consistency test (PCT). These results point towards the development of a glass ceramic waste form for treating CS+LN or CS+LN+TM combined waste streams. Three main benefits for exploring glass ceramics are: (1) Glass ceramics offer increased solubility of troublesome components in crystalline phases as compared to glass, leading to increased waste loading; (2) The crystalline network formed in the glass ceramic results in higher heat tolerance than glass; and (3) These glass ceramics are designed to be processed by the same melter technology as the current baseline glass waste form. It will only require adding controlled canister cooling for crystallization into a glass ceramic waste form. Highly annealed waste form (essentially crack free) with up to 50X lower surface area than a typical High-Level Waste (HLW) glass canister. Lower surface area translates directly into increased durability. This was the first full year of exploring glass ceramics for the Option 1 and 2 combined waste stream options. This work has shown that dramatic increases in waste loading are achievable by designing a glass ceramic waste form as an alternative to glass. Table S1 shows the upper limits for heat, waste loading (based on solubility), and the decay time needed before treatment can occur for glass and glass ceramic waste forms. The improvements are significant for both combined waste

  11. Structural chemistry and magnetic properties of LnMnFeGe4O12 (Ln = Y, Eu, Lu)

    Science.gov (United States)

    Xu, Diming; Avdeev, Maxim; Battle, Peter D.; Cadogan, J. M.; Lamont, Henry

    2017-10-01

    Polycrystalline samples of LnMnFeGe4O12 (Ln = Y, Eu, Lu) have been prepared using the ceramic method and characterised by a combination of magnetometry, Mössbauer spectroscopy, X-ray diffraction and neutron diffraction. They all adopt the space group P4/nbm with a 9.670, c 4.81 Å and show long-range antiferromagnetic order with transition temperatures 15 ≤ TN/K ≤ 17. The magnetic structure is the same in each case and consists of an A-type ordering of (001) planes; the ordered spins lie in the (001) plane. Comparison with isostructural compounds leads to the conclusion that subtle structural changes play a greater role than the electronic configuration of the cation in determining the magnetic structure.

  12. Observation of upconversion white light and ultrabroad infrared emission in YbAG:Ln3+ (Ln = Nd, Sm, Tb, Er)

    Science.gov (United States)

    Zhu, Yongsheng; Cui, Shaobo; Liu, Mao; Liu, Xuyan; Lu, Cheng; Xu, Xiumei; Xu, Wen

    2015-07-01

    We report on the intense white-light upconversion and ultrabroad infrared (IR) emission for the sol-gel synthesis of Yb3Al5O12 (YbAG):Ln3+ (Ln = Nd, Sm, Tb, Er) following excitation with low-energy near-infrared light (λex = 980 nm). Sufficient cross relaxations and photon avalanches play important roles in the formation of efficient visible and IR broad bands. The brightness of white-light upconversion was 6.2 × 104 cd/m2 at a laser power of 1.47 W, and the IR broad bands (1200-1700 nm) covered all the bands in optical communication media, which indicates that the material might be promising for the development of devices such as white lasers, LEDs, and integrated waveguides.

  13. Quaternary equiatomic compounds LnZnSbO(Ln=La-Nd, Sm) with ZrCuSiAs-type structure

    Energy Technology Data Exchange (ETDEWEB)

    Wollesen, P.; Kaiser, J.W.; Jeitschko, W. [Muenster Univ. (Germany). Anorganisch-Chemisches Inst.

    1997-12-01

    The five compounds LnZnSbO (Ln = La - Nd, Sm) were prepared by annealing cold-pressed pellets of the lanthanoids, zinc oxide, and antimony, or by reacting these components in a NaCl/KCl flux. They crystallize with the tetragonal ZrCuSiAs type structure, which was refined from single-crystal X-ray data of CeZnSbO : P 4/nmm, a = 419.76(4), c = 947.4(1) pm, Z = 2, R = 0.022 for 165 structure factors and 12 variable parameters. Chemical bonding in this and the formally isotypic compound CeZn{sub 1-x}Sb{sub 2} is briefly discussed. (orig.) 36 refs.

  14. 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.

  15. 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.

  16. Synthesis and structural diversity of trivalent rare-earth metal diisopropylamide complexes.

    Science.gov (United States)

    Spallek, Tatiana; Heß, Oliver; Meermann-Zimmermann, Melanie; Meermann, Christian; Klimpel, Michael G; Estler, Frank; Schneider, David; Scherer, Wolfgang; Tafipolsky, Maxim; Törnroos, Karl W; Maichle-Mössmer, Cäcilia; Sirsch, Peter; Anwander, Reiner

    2016-09-21

    A series of rare-earth metal diisopropylamide complexes has been obtained via salt metathesis employing LnCl3(THF)x and lithium (LDA) or sodium diisopropylamide (NDA) in n-hexane. Reactions with AM : Ln ratios ≥3 gave ate complexes (AM)Ln(NiPr2)4(THF)n (n = 1, 2; Ln = Sc, Y, La, Lu; AM = Li, Na) in good yields. For smaller rare-earth metal centres such as scandium and lutetium, a Li : Ln ratio = 2.5 accomplished ate-free tris(amido) complexes Ln(NiPr2)3(THF). The chloro-bridged dimeric derivatives [Ln(NiPr2)2(μ-Cl)(THF)]2 (Ln = Sc, Y, La, Lu) could be obtained in high yields for Li : Ln = 1.6-2. The product resulting from the Li : La = 1 : 1.6 reaction revealed a crystal structure containing two different molecules in the crystal lattice, [La(NiPr2)2(THF)(μ-Cl)]2·La(NiPr2)3(THF)2. Recrystallization of the chloro-bridged dimers led to the formation of the monomeric species Ln(NiPr2)2Cl(THF)2 (Ln = Sc, Lu) and La(NiPr2)3(THF)2. The reaction of YCl3 and LDA with Li : Y = 2 in the absence of THF gave a bimetallic ate complex LiY(NiPr2)4 with a chain-like structure. For scandium, the equimolar reactions with LDA or NDA yielded crystals of tetrametallic mono(amido) species, {[Sc(NiPr2)Cl2(THF)]2(LiCl)}2 and [Sc(NiPr2)Cl2(THF)]4, respectively. Depending on the Ln(iii) size, AM, and presence of a donor solvent, ate complexes (AM)Ln(NiPr2)4(THF)n show distinct dynamic behaviour as revealed by variable temperature NMR spectroscopy. The presence of weak LnCH(iPr) β-agostic interactions, as indicated by Ln-N-C angles <105°, is corroborated by DFT calculations and NBO analysis.

  17. Structurally flexible and solution stable [Ln4TM8(OH)8(L)8(O2CR)8(MeOH)y](ClO4)4

    DEFF Research Database (Denmark)

    Hooper, Thomas N.; Inglis, Ross; Lorusso, Giulia

    2016-01-01

    and in high yields from the reaction of Ln(NO3)3·6H2O and TM(ClO4)2·6H2O and the appropriate ligand blend in a mixture of CH2Cl2 and MeOH in the presence of a suitable base. Remarkably, almost all the constituent parts, namely the lanthanide (or rare earth) ions LnIII (here Ln = Gd or Y), the transition metal...... of diamagnetic complex 1b reveals the complex to be fully intact in solution with all signals from the hydroxide, ligand L, and the carboxylates equivalent on the NMR time scale, suggesting the complex possesses greater symmetry in solution than in the solid state. High resolution nano-ESI mass spectrometry...... on dichloromethane solutions of 2a and 2b shows both complexes are present in two charge states with little fragmentation; with the most intense peak in each spectrum corresponding to [Ln4Cu8(OH)8(hmp)8(O2CiPr)8](ClO4)2 2+. This family of compounds offers an excellent playground for probing how the magnetocaloric...

  18. Characterization and properties of new dielectric ceramics Ba5LnZnNb9O30(Ln=La,Nd and Sm)

    Institute of Scientific and Technical Information of China (English)

    ZHU Wen-feng; HU Chang-zheng; WU Bo-lin; FANG Liang

    2006-01-01

    Three novel dielectric ceramics Ba5LnZnNb9O30 (Ln= La,Nd and Sm) were synthesized and characterized in the BaO-Ln2O3-ZnO-Nb2O5 quaternary system,which formed the filled tungsten-bronze structures. The present ceramics exhibit high dielectric constant (εr) up to 310,low dielectric loss in the level of 10-3 at 1 MHz . Meanwhile,the temperature coefficients of the dielectric constant (τε) of Ba5LnZnNb9O30 varies from -1 390×10-6 to -1 220×10-6/℃ as the radius of Ln3+ increases. The present ceramics are promising candidates for high dielectric constant and low loss dielectric ceramics.

  19. Exploring the effect of the Ln(III)/Ln(II) redox potential on C-F activation and on oxidation of some lanthanoid organoamides.

    Science.gov (United States)

    Deacon, Glen B; Junk, Peter C; Kelly, Rory P; Wang, Jun

    2016-01-28

    The divalent europium complexes, and (L(Me/Et) = p-HC6F4N(CH2)2NMe2/Et2), have been prepared from redox-transmetallation/protolysis (RTP) reactions between Eu metal, Hg(C6F5)2 and L(Me/Et)H in thf. The complexes exhibit close (C)F-Ln interactions and the amide ligands feature tridentate N,N',F chelation. The complexes are thermally robust but on exposure to light they undergo C-F activation. From exposure of to light, the Eu(III) mixed fluoride/oxide cluster, was isolated, but other well-defined C-F activation products have proven elusive due to the stability of Eu(II). Oxidation of [Ln(L(R))2(thf)2] (Ln = Eu, R = Me; Ln = Yb, R = Et) with I2 afforded the heteroleptic iodo complexes, [Ln(L(R))2I(thf)n] (Ln = Eu, n = 1; Ln = Yb, n = 0), and the homoleptic complexes, [Ln(L(R))3]. The formation of the iodo complexes and the heteroleptic complexes appear to occur by different routes. shows interesting structural differences from reported [Ln(L(Et))3] (Ln = La, Ce, Nd) complexes, and highlights an incomplete shift towards N,N' chelation to the much smaller Yb ion. was prepared from a protolysis reaction between [Sm(CH2C6H4-NMe2-o)3] and L(Me)H. Heating a solution of in toluene at 110 °C for three days did not afford any samarium fluoride complex. An RTP reaction with Sm afforded the heteroleptic samarium complex, , in very low yield. From an attempted protolysis reaction between [Sm(DippForm)2(thf)2] and L(Me)H, the mixed ligand samarium fluoride complex, , was isolated. Overall, the instability of Sm(II) precludes control over the C-F activation reactions.

  20. Matrix-induced synthesis and photoluminescence of M{sub 3}Ln(VO{sub 4}){sub 3}:RE (M Ca, Sr, Ba; Ln = Y, Gd; RE = Eu{sup 3+}, Dy{sup 3+}, Er{sup 3+}) phosphors by hybrid precursors

    Energy Technology Data Exchange (ETDEWEB)

    Su Xueqing [Department of Chemistry, Tongji University, Shanghai 200092 (China); Yan, Bing [Department of Chemistry, Tongji University, Shanghai 200092 (China)]. E-mail: byan@tongji.edu.cn

    2006-09-14

    Using rare earth coordination polymers with salicylic acid as precursors, composing with the polyethylene glycol (PEG) as dispersing media, the phosphor particles of M{sub 3}Ln(VO{sub 4}){sub 3}:RE (M = Ca, Sr, Ba; Ln = Y, Gd; RE Eu{sup 3+}, Dy{sup 3+}, Er{sup 3+}) were firstly synthesized via a novel modified in situ chemical co-precipitation technology. Their micromorphology and particles have been analyzed by X-ray powder diffraction (XRD) and scanning electronic microscope (SEM), which indicate that these materials have the micrometer size. And all the characteristic transitions of the doped rare earth ions can be detected in all the host lattices.

  1. Crystal chemistry and electrical conductivity of Ln{sub 2}Eu{sub 2}O{sub 3}F{sub 6} (Ln: Nd, La)

    Energy Technology Data Exchange (ETDEWEB)

    Takashima, Masayuki [Cooperative Research Center, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507 (Japan)]. E-mail: takashima@matse.fukui-u.ac.jp; Yonezawa, Susumu [Department of Materials Science and Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507 (Japan)]. E-mail: yonezawa@matse.fukui-u.ac.jp; Kim, Jeo-ho [Department of Materials Science and Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507 (Japan)

    2006-02-09

    Binary rare-earth metal oxide fluorides Ln{sub 2}Eu{sub 2}O{sub 3}F{sub 6} were synthesized by the solid-state reaction between 1mol Ln{sub 2}O{sub 3} (Ln: La, Nd) and 2mol EuF{sub 3} at 1000-1200{sup o}C in a highly dry atmosphere. Nd{sub 2}Eu{sub 2}O{sub 3}F{sub 6} exhibits the oxide ion conductivity of 2.0Sm{sup -1} at 500{sup o}C under P{sub O{sub 2}}=0.4Pa, and the transport numbers {tau}O{sup 2-} was 0.9 at a temperature ranging from 500 to 700{sup o}C. X-ray diffraction Rietveld analysis revealed Nd{sub 2}Eu{sub 2}O{sub 3}F{sub 6} was the monoclinic lattice with the crystal parameters a{sub 0}=0.396nm, b{sub 0}=1.13nm, c{sub 0}=0.562nm, b=134.8{sup o}, Z=1. The structures of Nd{sub 2.1}Eu{sub 1.9}O{sub 3}F{sub 6} and La{sub 2}Eu{sub 2}O{sub 3}F{sub 6} were also analyzed as the monoclinic structure (a{sub 0}=0.397nm, b{sub 0}=1.13nm, c{sub 0}=0.561nm, {beta}=135.0{sup o}, Z=1 for Nd{sub 2.1}Eu{sub 1.9}O{sub 3}F{sub 6} and a{sub 0}=0.404nm, b{sub 0}=1.14nm, c{sub 0}=0.574nm, {beta}=135.3{sup o}, Z=1 for La{sub 2}Eu{sub 2}O{sub 3}F{sub 6}). The ionic arrangement was suggested to be not a little disordered in the crystal lattice of Nd{sub 2.1}Eu{sub 1.9}O{sub 3}F{sub 6} and La{sub 2}Eu{sub 2}O{sub 3}F{sub 6} in contrast to that in the Nd{sub 2}Eu{sub 2}O{sub 3}F{sub 6}. The disorder of anionic arrangement in Nd{sub 2.1}Eu{sub 1.9}O{sub 3}F{sub 6} and La{sub 2}Eu{sub 2}O{sub 3}F{sub 6} lattice was assumed to result in the lower oxide ion conductivity Nd{sub 2.1}Eu{sub 1.9}O{sub 3}F{sub 6} ({sigma}=1.0Sm{sup -1}, {tau}O{sup 2-}=0.9) and La{sub 2}Eu{sub 2}O{sub 3}F{sub 6} ({sigma}=0.8Sm{sup -1}, {tau}O{sup 2-}=0.7)

  2. Synthesis and Characterization of Ethylthioethylcyclopentadienyl Organolanthanide Complexes:Cp2Th LnCl (Ln=Gd, Dy), Cp2LnCpTh (Ln=Yb, Sm, Dy, Y) and Cp2ThErCl2·2THF

    Institute of Scientific and Technical Information of China (English)

    ZHU Ming朱铭; ZHANG Li-Bei张丽蓓; CHEN Ying-Hua陈应华; ZHOU Xi-Geng周锡庚; CAI Rui-Fang蔡瑞芳; WENG Lin-Hong翁林红

    2004-01-01

    Six new ethylthioethylcyclopentadienyl-containing organolanthanide complexes Cp2Th LnCl [Ln=Gd (1), Dy (2)]and Cp2LnCpTh [Cp=C5H5, Ln=Yb (3), Sm (4), Dy (5), Y (6)] were synthesized by the reaction of ethylthioethylcyclopentadienyl (CpTh) sodium salt with LnC13 or Cp2LnCl in THF. Complexes 1-6 were characterized by elemental analyses, infrared and mass spectroscopies. The molecular structures of complexes 1-3 were also determined by the X-ray single crystal diffraction. The results show that the side-chain sulfur atom on the ethylthioethylcyclopentadienyl ring can form intramolecular chelating coordination to the central lanthanide ion, improving the stability of organolanthanide complexes and reducing the number of coordinated THF molecules.

  3. The calcium and rare earth oxo-borates, Ca{sub 4}ReO(BO{sub 3}){sub 3} (Re = Gd, Y, La): synthesis and investigations of new non-critical phase matching configurations for frequency conversion at specific laser wavelengths; Les oxoborates de calcium et de lanthanide, Ca{sub 4}LnO(BO{sub 3}){sub 3} (Ln = Gd, Y, La): synthese et recherche d'angles d'accord de phase non critique pour la conversion de frequence de longueurs d'onde Laser specifiques

    Energy Technology Data Exchange (ETDEWEB)

    Reino, E

    2002-12-15

    Visible and UV lasers are currently investigated for many applications as data storage, medicine, etc. Intracavity frequency doubling appears as a good solution. Thus, the non-linear family Ca{sub 4}REO(BO{sub 3}){sub 3} (RE = rare earth, RECOB) has shown a considerable interest to produce compact visible laser. In addition, it is possible to tune the compositions of RECOB by partial substitutions in order to achieve non-critical phase matching (NCPM). In the present work, various cationic substitutions have been studied in solid solutions as Gd{sub 1-x}Y{sub x}COB, Gd{sub 1-x}La{sub x}COB, Gd{sub 1-x}Sc{sub x}COB (for the first time), Re{sub 1-x}Bi{sub x}COB (REe = Gd or Y) and (Ca{sub 1-x}Sr{sub x}){sub 4}GdO(BO{sub 3}){sub 3} in order to investigate their crystal growth and adjust the NCPM wavelength by composition. The wavelength range is related to neodymium doped laser materials emitting on the 4F3/2-4I9/2 transition, for example Nd:YAP (YAlO{sub 3}) at 930 nm, Nd:YAG (Y{sub 3}Al{sub 5}O{sub 12}) at 946 nm or Nd:ASL (Sr{sub 1-x}Nd{sub y}La{sub x-y}Mg{sub x}Al{sub 11-x}O{sub 19}) at 900 nm. We have also demonstrated that the compositions for NCPM can be determined from the refractive index of both lattices M{sub 1-x}M'{sub x}COB (M, M' RE) with x = 0 or 1, using the Clausius-Mosotti relation. Two new blue laser systems, constituted of a laser crystal and a non-linear crystal optimized for type-I NCPM second harmonic generation, were achieved: a 946 nm Nd:YAG laser with Gd{sub 0.87}Y{sub 0.13}COB and a 900 nm Nd:ASL laser with Gd{sub 0.56}Y{sub 0.44}COB. Moreover, we have performed for the first time a CW laser action at 900 nm with Nd:ASL. (author)

  4. Charge-order driven multiferroic and magneto-dielectric properties of rare earth manganates

    Indian Academy of Sciences (India)

    Claudy Rayan Serrao; Jyoti Ranjan Sahu; Anirban Ghosh

    2010-04-01

    Charge-order driven magnetic ferroelectricity is shown to occur in several rare earth manganates of the general formula, Ln1–AMnO3 (Ln = rare earth, A = alkaline earth). Charge-ordered manganates exhibit dielectric constant anomalies around the charge-ordering or the antiferromagnetic transition temperature. Magnetic fields have a marked effect on the dielectric properties of these compounds, indicating the presence of coupling between the magnetic and electrical order parameters. Magneto-dielectric properties are retained in small particles of the manganates. The observation of magneto-ferroelectricity in these manganates is in accordance with theoretical predictions.

  5. Synthesis, structure, magnetic and transport properties of LnFeSb3 (Ln = Pr, Nd, Sm, Gd, and Tb)--tuning of anisotropic long-range magnetic order as a function of Ln.

    Science.gov (United States)

    Phelan, W Adam; Nguyen, Giang V; Karki, Amar B; Young, David P; Chan, Julia Y

    2010-07-28

    Single crystals of LnFeSb(3) (Ln = Pr, Nd, Sm, Gd, and Tb) have been grown from excess Sb flux. The crystal structure consists of (infinity)(2)[FeSb(2)] octahedra separated by layers of Ln atoms and nearly square planar nets of (infinity)(2)[Sb(2)]. These compounds are metallic and display anisotropic magnetic properties. Long-range antiferromagnetic order is observed in the Sm, Gd, and Tb samples when the magnetic field is applied along the crystallographic a-axis. Evidence of magnetic ordering in all the samples is observed for the field applied parallel to the layers. The magnetic properties are well-described by considering only the magnetic interactions between the Ln 4f moments, with no contribution from the Fe sublattice. Herein, we report the crystal growth, structure, magnetization, transport, and chemical stabilities of the title compounds.

  6. Convergence Rate of the L-N Estimator in Poisson-Gamma Models

    Institute of Scientific and Technical Information of China (English)

    Na Xia; Zhong-zhan Zhang; Zhi-liang Ying

    2006-01-01

    We focus on in this paper the convergence rate of the L-N estimators for the fixed effect β in Poisson-Gamma models which are typical hierarchical generalised linear models(HGLMs). Under the proper assumptions on response variables and some smoothing conditions, we obtain the strong consistency and the convergence rate of the L-N estimator based on the combination of L-N and quasi-likelihood.

  7. Ab initio prediction of the electronic, magnetic and topological properties of Ln2O3 clusters

    Science.gov (United States)

    Xia, Xiuli; Shao, Yuanzhi

    2017-07-01

    The structural, electronic and magnetic properties of the lanthanide oxide Ln2O3 clusters, where Ln signifies lanthanides from La to Lu, have been calculated using spin-polarized density functional theory with the B3LYP hybrid functional. The intensities of ferromagnetic RKKY interaction are found comparable with that of antiferromagnetic superexchange interaction in Ce2O3 / Pr2O3 / Nd2O3 / Gd2O3 / Tb2O3 / Tm2O3 clusters, while the other Ln2O3 clusters prefer ferromagnetic states to antiferromagnetic states in energy, except nonmagnetic La2O3 and Lu2O3 clusters. The theoretical spin magnetic moments, calculated three-dimensional spin density maps and dipole moments of Ln2O3 clusters suggest that the induced polarizations of oxygen atoms in Sm2O3, Eu2O3 and Yb2O3 clusters remarkably lead to the elongated Ln-O bond lengths in these clusters. The partial density of states of Ln2O3 clusters reveals that Sm3+ /Eu3+ /Yb3+ ions are distinctive from other Ln3+ ions in that their Ln-4f electrons are strongly hybrid with O-2 p electrons. The topological analysis of the electron density was also performed with quantum theory of atoms in molecules, which indicates the ionic Ln-O bonds have partial covalent characteristics.

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

    Science.gov (United States)

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

    2014-11-17

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

  9. Solid-state synthesis of monazite-type compounds LnPO{sub 4} (Ln = La to Gd)

    Energy Technology Data Exchange (ETDEWEB)

    Bregiroux, D.; Audubert, F. [CEA Cadarache (DEN/DEC/SPUA/LTEC), 13 - Saint-Paul-lez-Durance (France). Dept. d' Etudes des Combustibles; Bregiroux, D. [Laboratoire Science des Procedes Ceramiques et de Traitements de Surface, UMR CNRS-Universite 6638, 87 - Limoges (France); Charpentier, Th.; Sakellariou, D. [CEA Saclay (DSM/DRECAM/SCM/LSDRM), CEA-CNRS URA 331, 91 - Gif-sur-Yvette (France). Direction des Sciences de la Matiere; Bernache-Assollant, D. [Ecole Nationale Superieure des Mines, CIS, 42 - Saint Etienne (France)

    2007-07-01

    This work is devoted to the synthesis of monazite-type compounds LnPO{sub 4} (with Ln = La, Ce, Pr, Nd, Sm, Eu and Gd) by solid-solid reaction between a lanthanide oxide and a phosphate precursor NH{sub 4}H{sub 2}PO{sub 4}. Starting mixtures and resulting powders were characterized by coupling different techniques, in particular thermal analysis, X-ray diffraction and MAS {sup 31}P NMR. Results are presented according to the valence state of the lanthanide element in its oxide form. The intermediate chemical reactions occurring during the firing of starting reagents are described for the first time in the case of monazite with one or several cations. It has been highlighted that the solid-state route is an efficient way in order to obtain very pure and very well crystallized monazite powder. Optimum synthesis conditions are 1350 C-2h. The synthesis of monazite powders containing several lanthanides appears to be more difficult, because all the lanthanides do not react at the same temperature, leading to the formation of heterogeneous powders. (authors)

  10. Thermodynamic studies on LnCoO{sub 3}(s) (Ln = Dy, Ho) by solid-state electrochemical cells

    Energy Technology Data Exchange (ETDEWEB)

    Patil, Abhay [Product Development Section, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Dash, Smruti [Product Development Section, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)], E-mail: smruti@barc.gov.in; Parida, S.C.; Venugopal, V. [Product Development Section, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2009-01-05

    Ternary oxides, DyCoO{sub 3}(s) and HoCoO{sub 3}(s) have been synthesized by citrate-nitrate gel combustion method and characterized by X-ray powder diffraction method. The standard molar Gibbs energies of formation of DyCoO{sub 3}(s) and HoCoO{sub 3}(s) have been measured using solid oxide galvanic cell technique employing yttria-stabilized zirconia (YSZ) and calcia-stabilized zirconia (CSZ) as solid electrolyte tubes, respectively. The standard molar Gibbs energies of formation of DyCoO{sub 3}(s) and HoCoO{sub 3}(s) were calculated from the measured e.m.f. data and are given as: {delta}{sub f}G{sub m}{sup o}(DyCoO{sub 3},s,T)kJmol{sup -1}({+-}4)=-1211.3+0.2449{sup *}(TK),(1013K{<=}T{>=}1167K), {delta}{sub f}G{sub m}{sup o}(HCoO{sub 3},s,T)kJmol{sup -1}({+-}4)=-1237.8+0.2590{sup *}(TK).(964K{<=}T{>=}1102K), A set of self consistent thermodynamic functions for LnCoO{sub 3}(s) (Ln = La, Nd, Sm, Eu, Gd, Dy, Ho) has been computed from available experimental data in the literature.

  11. Photoluminescent properties of Eu{sup 3+}, Tb{sup 3+} activated M{sub 3}Ln(PO{sub 4}){sub 3} (M = Sr, Ca; Ln = Y, La, Gd) phosphors derived from hybrid precursors

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Xiuzhen [Department of Chemistry, Tongji University, Shanghai 200092 (China); Xu, Shuai [Department of Chemistry, Tongji University, Shanghai 200092 (China); Yan, Bing [Department of Chemistry, Tongji University, Shanghai 200092 (China)]. E-mail: byan@tongji.edu.cn

    2007-02-21

    Ternary orthophosphates M{sub 3}Ln(PO{sub 4}){sub 3} doped with Eu{sup 3+}, Tb{sup 3+} were prepared via an in situ chemical co-precipitation technology, and the assembly process of hybrid precursors were as follows: using rare-earth coordination polymers with salicylic acid as precursors and composing with the polyvinyl alcohol (PVA) as dispersing media. Their microstructure and micromorphology have been analyzed by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The emission spectra exhibited strong luminescence of {sup 5}D{sub 0} {sup {yields}} {sup 7}F{sub 2} at 609 nm, indicating that the Eu{sup 3+} located in a noncentrosymmetric position in Eu-doped M{sub 3}Ln (PO{sub 4}){sub 3} matrix. Besides this, the values of red to orange emission intensities for Eu{sup 3+} in Sr{sub 3}Gd (PO{sub 4}){sub 3} strongly depend on the doping concentration.

  12. 4X6" Rotary Bayonet LN2 Test Fill

    Energy Technology Data Exchange (ETDEWEB)

    Fitzpatrick, J.B.; /Fermilab

    1988-08-02

    This engineering note describes a test fill of the 4-inch x 6-inch rotary bayonet test fixture with LN{sub 2}. This test verifies the operation of valves on the fixture, and checks for proper construction/insulation. Further cold testing is imminent (with rotation and moment loading of the bayonet) after proper construction is verified and the test fixture is accepted. While this test fixture is a pressure vessel (4-inch), it does not require special safety treatment because it is under 6-inch in diameter. Flow capacity calculations were done to insure that the relief valve chosen would be capable of handling fire/loss of vacuum conditions. The D-Zero Safety Committee Chairman was notified of this testing.

  13. Ultralarge 3d/4f Coordination Wheels: From Carboxylate/Amino Alcohol-Supported {Fe4Ln2} to {Fe18Ln6} Rings

    Science.gov (United States)

    2017-01-01

    A family of wheel-shaped charge-neutral heterometallic {FeIII4LnIII2}- and {FeIII18MIII6}-type coordination clusters demonstrates the intricate interplay of solvent effects and structure-directing roles of semiflexible bridging ligands. The {Fe4Ln2}-type compounds [Fe4Ln2(O2CCMe3)6(N3)4(Htea)4]·2(EtOH), Ln = Dy (1a), Er (1b), Ho (1c); [Fe4Tb2(O2CCMe3)6(N3)4(Htea)4] (1d); [Fe4Ln2(O2CCMe3)6(N3)4(Htea)4]·2(CH2Cl2), Ln = Dy (2a), Er (2b); [Fe4Ln2(O2CCMe3)4(N3)6(Htea)4]·2(EtOH)·2(CH2Cl2), Ln = Dy (3a), Er (3b) and the {Fe18M6}-type compounds [Fe18M6(O2CCHMe2)12(Htea)18(tea)6(N3)6]·n(solvent), M = Dy (4, 4a), Gd (5), Tb (6), Ho (7), Sm (8), Eu (9), and Y (10) form in ca. 20–40% yields in direct reaction of trinuclear FeIII pivalate or isobutyrate clusters, lanthanide/yttrium nitrates, and bridging triethanolamine (H3tea) and azide ligands in different solvents: EtOH for the smaller {Fe4Ln2} wheels and MeOH/MeCN or MeOH/EtOH for the larger {Fe18M6} wheels. Single-crystal X-ray diffraction analyses revealed that 1–3 consist of planar centrosymmetric hexanuclear clusters built from FeIII and LnIII ions linked by an array of bridging carboxylate, azide, and aminopolyalcoholato-based ligands into a cyclic structure with a cavity, and with distinct sets of crystal solvents (2 EtOH per formula unit in 1a–c, 2 CH2Cl2 in 2, and 2 EtOH and 2 CH2Cl2 in 3). In 4–10, the largest 3d/4f wheels currently known, nearly linear Fe3 fragments are joined via mononuclear Ln/Y units by a set of isobutyrates and amino alcohol ligands into virtually planar rings. The magnetic properties of 1–10 reveal slow magnetization relaxation for {Fe4Tb2} (1d) and slow relaxation for {Fe4Ho2} (1c), {Fe18Dy6} (4), and {Fe18Tb6} (6). PMID:28135085

  14. Effect of inclining strain on the crystal lattice along an extended series of lanthanide hydroxysulfates Ln(OH)SO4 (Ln = Pr-Yb, except Pm).

    Science.gov (United States)

    Zehnder, Ralph A; Wilson, Christopher S; Christy, Hunter T; Harris, Kenneth S; Chauhan, Varun; Schutz, Victor; Sullivan, Matthew; Zeller, Matthias; Fronczek, Frank R; Myers, Jacob A; Dammann, Kyle; Duck, James; Smith, Peter M; Okuma, Antony; Johnson, Kristin; Sovesky, Robert; Stroudt, Cameron; Renn, Robert A

    2011-02-07

    A series of trivalent lanthanide hydroxysulfates, Ln(OH)SO(4), (Ln = Pr through Yb, except radioactive Pm) has been synthesized via hydrothermal methods from Ln(2)(SO(4))(3)·8H(2)O by reaction with aqueous NaOH at 170 °C in Teflon lined Parr steel autoclaves, and were characterized by single crystal X-ray diffraction and FT-IR spectroscopy. Two types of arrangements were found in the solid state. The lighter (Ln = Pr-Nd, Sm-Gd) and heavier lanthanide(III) hydroxysulfates (Tb-Yb) are each isostructural. Both structure types exhibit the monoclinic space group P2(1)/n, but the unit cell content is doubled with two crystallographically distinct LnO(8) polyhedra for the heavier lanthanide compounds. The lighter complexes maintain the coordination number 9, forming a three-dimensional extended lattice. The heavier counterparts exhibit the coordination number 8, and arrange as infinite columns of two crystallographically different LnO(8) polyhedra, while extending along the "c" axis. These columns of LnO(8) polyhedra are surrounded and separated by six columns of sulfate ions, also elongating in the "c" direction. The rigid sulfate entities seem to obstruct the closing in of the lighter LnO(9) polyhedra, and show an inclining degree of torsion into the "ac" layers. The crystal lattice of the lighter 4f complexes can sufficiently withstand the tension buildup, caused by the decreasing Ln(3+) radius, up to Gd(OH)SO(4). The energy profile of this structural arrangement then seems to exceed levels at which this structure type is favorable. The lattice arrangement of the heavier Ln-analogues seems to offer a lower energy profile. This appears to be the preferred arrangement for the heavier lanthanide hydroxysulfates, whose crystal lattice exhibits more flexibility, as the coordination sphere of these analogues is less crowded. The IR absorbance frequencies of the hydroxide ligands correlate as a function of the Ln(3+) ionic radius. This corresponds well with the X-ray single

  15. Ligand-Free Synthesis of Tunable Size Ln:BaGdF5 (Ln = Eu3+ and Nd3+) Nanoparticles: Luminescence, Magnetic Properties, and Biocompatibility

    OpenAIRE

    Becerro, Ana Isabel; González-Mancebo, D.; Cantelar, Eugenio; Cussó, Fernando; Stepien, Grazyna; Fuente, J.M. de la; Ocaña, Manuel

    2016-01-01

    Bifunctional and highly uniform Ln:BaGdF5 (Ln = Eu3+ and Nd3+) nanoparticles have been successfully synthesized using a solvothermal method consisting of the aging at 120 °C of a glycerol solution containing the corresponding Lanthanide acetylacetonates and butylmethylimidazolium tetrafluoroborate. The absence of any surfactant in the synthesis process rendered hydrophilic nanospheres (with tunable diameter from 45 nm 85 nm, depending on the cations concentration of the starting solution) whi...

  16. 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).

  17. Complexation of amidocarbamoyl phosphine oxides with Ln{sup +3} (Ln = La, Nd, Pm, Sm and Eu) cation series: structural and thermodynamical features

    Energy Technology Data Exchange (ETDEWEB)

    Hosseinnejad, Tayebeh; Kazemi, Tayebeh [Alzahra Univ., Tehran (Iran, Islamic Republic of). Dept. of Chemistry

    2016-05-01

    In the present study, we have mainly investigated the nature of interactions in Ln{sup 3+} (Ln = La, Nd, Pm, Sm, Eu) complexes with amidocarbamoyl methyl phosphine oxide (CMPO) and amidocarbamoyl propyl phosphine oxide (CPPO) ligands based on density functional theory (DFT) approaches. In the first step, thermodynamical properties for complexation of CMPO and CPPO ligands with Ln{sup 3+} cation series have been determined in the gas phase and with the presence of three solvents: n-hexane, chloroform and toluene, via polarized continuum model (PCM) computations. The trend of metal-ligand interaction strength has been analyzed and compared with the trend of ionic hardness within the series of lanthanide cations and different size of alkyl chain of amidocarbamoyl phosphine oxide ligand. The calculated thermochemical results in the gas and solution phases reveals that there is a consistency between increasing trend in the hardness of Ln{sup 3+} cation series and also electron-donating property of alkyl chain with increasing in thermodynamical stability of [Ln-CMPO]{sup 3+} and [Ln-CPPO]{sup 3+} complex series. We have also demonstrated that in the complexation reaction of all complex series, using n-hexane as solvent is more favorable thermodynamically than chloroform and toluene. It should be stated that this issue has been observed in many experiments. Finally, analysis of calculated deformation energies and also the variation in bond order of some selected key bonds in CMPO and CPPO ligands and their corresponded Ln{sup 3+} complexes series show a similar trend with increasing in the hardness of Ln{sup 3+} cation series and electron-donating of alkyl chain of amidocarbamoyl phosphine oxide ligand.

  18. Vibrational spectra and structural considerations of compounds NaLnTiO4

    NARCIS (Netherlands)

    Blasse, G.; Heuvel, G.P.M. van den

    1974-01-01

    The Raman and infrared spectra of compounds NaLnTiO4 (Ln = lanthanide, including yttrium) are reported and discussed. Their most striking feature is a strong band in both spectra at about 900 cm−1. This band is ascribed to a vibration localized in the Ti---O bond directed towards the Na---O layers.

  19. Structural anomalies associated with the electronic and spin transitions in LnCoO(3)

    NARCIS (Netherlands)

    Knizek, K; Jirak, Z; Hejtmanek, J; Veverka, M; Marysko, M; Maris, G; Palstra, TTM; Knížek, K.; Maryško, M.

    2005-01-01

    A powder X-ray diffraction study, combined with magnetic susceptibility and electric transport measurements, was performed on a series of LnCoO(3) perovskites (Ln = Y, Dy, Gd, Sm, Nd, Pr and La) over a temperature range 100-1000 K. A non-standard temperature dependence of the observed thermal expans

  20. Linking two distinct layered networks of nanosized {Ln18} and {Cu24} wheels through isonicotinate ligands.

    Science.gov (United States)

    Cheng, Jian-Wen; Zhang, Jie; Zheng, Shou-Tian; Yang, Guo-Yu

    2008-01-01

    A new series of heterolanthanide(III)-copper(I) wheel-cluster complexes [Ln6(micro3-O)2](IN)18-[Cu8(micro4-I)2(micro2-I)3].H3O (IN=isonicotinate; Ln=Y 1, Nd 2, Dy 3, Gd 4, Sm 5, Eu 6, Tb 7) were prepared by hydrothermal reaction at low pH. X-ray crystallographic studies reveal that two unusual trinuclear [Ln3(micro3-O)] and tetranuclear [Cu4(micro4-I)] cores are successfully used as secondary building units to make two different nanosized wheels [Ln18(micro3-O)6(CO2)48](6-), {Ln18}, and [Cu24(micro4-I)6(micro2-I)12]6+, {Cu24}, with 12-rings and a diameter of 26.7 and 26.4 A, respectively. The wheels are further assembled into two-dimensional (2D) {Ln18} and {Cu24} networks, the linkages between two distinct layered networks of {Ln18} and {Cu24} wheels by IN pillars along the c axis giving a series of unprecedented three-dimensional (3D) sandwich frameworks. To our knowledge, compounds 1-7 are the first examples containing two different layered networks of nanosized Ln and transition metal (TM) wheels in wheel-cluster chemistry. The IR, UV/Vis, thermogravimetric analysis (TGA), luminescent, and magnetic properties of these complexes were also studied.

  1. Synthesis, characterization and thermal behavior of rare earth amido sulfonates; Sintese, caracterizacao e comportamento termico de amidossulfonatos de terras raras

    Energy Technology Data Exchange (ETDEWEB)

    Luiz, Jose Marques; Nunes, Ronaldo Spezia, E-mail: jmluiz@feg.unesp.br [Universidade Estadual Paulista Julio Mesquita Filho (UNESP), Guaratingueta, SP (Brazil). Faculdade de Engenharia. Departamento de Fisica e Quimica; Matos, Jivaldo do Rosario [Universidade de Sao Paulo (USP), SP (Brazil). Instituto de Quimica

    2013-09-01

    Hydrated compounds prepared in aqueous solution by reaction between amidosulfonic acid [H{sub 3}NSO{sub 3}] and suspensions of rare earth hydroxycarbonates [Ln{sub 2}(OH){sub x}(CO{sub 3}){sub y}.zH{sub 2}O] were characterized by elemental analysis (% Ln, % N and % H), infrared spectroscopy (FTIR) and thermogravimetry (TG). The compounds presented the stoichiometry Ln(NH{sub 2}SO{sub 3}){sub 3}.xH{sub 2}O (where x = 1, 5, 2.0 or 3.0). The IR spectra showed absorptions characteristic of H{sub 2}O molecules and NH{sub 2}SO{sub 3} groups. Degree of hydration, thermal decomposition steps and formation of stable intermediates of the type [Ln{sub 2}(SO{sub 4}){sub 3}] and (Ln{sub 2}O{sub 2}SO{sub 4}), besides formation of their oxides, was determined by thermogravimetry. (author)

  2. Détermination structurale de la forme de haute température du composé La 4[Ge 3O 10][GeO 4]: Analyse comparative des structures tricliniques des germanates de terres rares de formule globale Ln2Ge 2O 7

    Science.gov (United States)

    Vetter, Geneviève; Queyroux, Francine

    1988-04-01

    The rare-earth germanates Ln2Ge 2O 7 have been structurally determined as three triclinic structural forms ( Ln = LaGd) and one tetragonal ( Ln = GdLu). The structural determination of the high temperature form La 2Ge 2O 7, which is presented here, gives rise to a fourth triclinic structural type. The complete description of the Ln2Ge 2O 7 phases, stable a ordinary pressure, is thus achieved. Refinement was carried out by the heavy atom method on a model which could be elaborated after the comparative study of the three triclinic forms. Space group: P1, a = 7.080(2), b = 7.101(3), c = 6.928(2) Å, α = 87.74(2), β = 91.25(2), γ = 115.81(2)°, Z = 2, R = 0.065, Rw = 0.083 for 4018 reflections. A global structural analysis of all the four triclinic phases is proposed.

  3. Expanding earth

    Energy Technology Data Exchange (ETDEWEB)

    Carey, S.W.

    1976-01-01

    Arguments in favor of an expanding earth are presented. The author believes that the theory of plate tectonics is a classic error in the history of geology. The case for the expanding earth is organized in the following way: introductory review - face of the earth, development of expanding earth concept, necessity for expansion, the subduction myth, and definitions; some principles - scale of tectonic phenomena, non-uniformitarianism, tectonic profile, paleomagnetism, asymmetry of the earth, rotation of the earth, and modes of crustal extension; regional studies - western North America, Central America, South-East Asia, and the rift oceans; tests and cause of expansion. 824 references, 197 figures, 11 tables. (RWR)

  4. Phase Behavior and Crystal Structure of Perovskite-Type Rare Earth Complex Oxides

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Several compounds of rare earth complex oxides containing manganese and titanium were synthesized in Ar, and their crystal structures were analyzed by powder X-ray diffraction data and Rietveld method. Structures of A0.67Ln0.33Mn0.33Ti0.67O3 (A=Ca or Sr and Ln=rare earth) were found to have orthorhombic symmetry with the space group Pnma, and their interatomic distances and bond angles were obtained. This space group was also derived from electron microscopic study. Electrical conductivity of Ca0.67Ln0.33Mn0.33Ti0.67O3 for several rare earth elements showed a semiconducting property with the activation energy of 0.4 eV. Some of these compounds of the strontium system show the antiferromagnetic properties below 10 K.

  5. Ab initio energetic study of oxide ceramics with rare-earth elements

    Institute of Scientific and Technical Information of China (English)

    WU Bo; Matvei Zinkevich; WANG Chong; Fritz Aldinger

    2006-01-01

    Ab initio energetic calculations based on the density functional theory (DFT) and the projector augmented wave method (PAW) for determining the polymorphisms of lanthanide sesquioxides Ln2O3 (where Ln = rare-earth element. Y,and Sc), LnMO3 perovskites (where M = Al and Ga), and Ln2B2O7 pyrochlores (where B = Ti, Zr, and Hf) were reported. The relative lattice stabilities agreed well with the critically assessed results or the experimental results except the C-type Ln2O3 with a cubic structure, for which the calculated total energies were considerably more negative. With the increase of the Ln3+-cation radius, the polymorphic structures showed a degenerative tendency. The tendencies and quantities of the enthalpies of formation of the ternary oxide ceramics synthesized from their constituent binary oxides reasonably agreed with the available experimental results, and valuable thermodynamic properties were afforded to the compound, for which no experimental data is available. The enthalpies of formation of both perovskites and pyrochlores tend to become more negative with the increase of the Ln3+-cation radius.

  6. Rare earth element geochemistry of groundwaters from coal bearing aquifer in Renlou coal mine, northern Anhui Province, China

    Institute of Scientific and Technical Information of China (English)

    SUN Linhua; GUI Herong; CHEN Song

    2011-01-01

    Rare earth element (REE) concentrations of two different types of groundwaters (high SO42- water-SW and high alkaline waterCW) from coal bearing aquifer (-400~-280 m) in Renlou coal mine, northern Anhui Province, China were measured. The results indicated that they had different REE characteristics: the total concentrations of REEs (∑REE) of SW were lower than those of CW in general although they all had heavy REEs enriched relative to light REEs. The dissolved REE inorganic species of SW included Ln3+, LnCO3+, LnSO4+,Ln(CO3)2- and Ln(SO4)2-, whereas the CW are Ln(CO3)2- and LnCO3+ dominant, and the proportions of Ln(CO3)2- increased while other species decreased with pH increasing. Combined with correlation analysis, the enrichment and fractionation of SW (low alkaline water) were considered to be affected by alkaline concentrations via affecting the types and proportons of REE inorganic species. However, the effect of alkaline concentrations to the enrichment and fractionation of REEs of CW (high alkaline water) was less important than total dissolved solids and pH, which reflected the contribution from different rocks they flowed over, different degrees of water-rock interactions and/or REE solid-liquid partition coefficients.

  7. 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.

  8. Salen-based [Zn2Ln3] complexes with fluorescence and single-molecule-magnet properties.

    Science.gov (United States)

    Burrow, Carolyn E; Burchell, Tara J; Lin, Po-Heng; Habib, Fatemah; Wernsdorfer, Wolfgang; Clérac, Rodolphe; Murugesu, Muralee

    2009-09-07

    A family of four isostructural complexes with a V-shaped pentanuclear [Zn(2)Ln(3)] core of general formula [Zn(2)Ln(3)(m-salen)(3)(N(3))(5)(OH)(2)] [Ln(III) = Tb(III) (1), Eu(III) (2), Ho(III) (3), Dy(III) (4); m-salen = N,N'-ethylenebis(3-methoxysalicylideneamine)] were isolated and structurally characterized. The fluorescence and magnetic measurements of the four compounds were investigated. Complex 1 exhibits strong fluorescence properties, while single-molecule-magnet behavior is seen in complex 4.

  9. Syntheses and Structures of the New Quaternary Rubidium Selenides Rb Ln2CuSe 4 ( Ln=Sm, Gd, Dy), Rb 1.5Ln2Cu 2.5Se 5 ( Ln=Gd, Dy), and RbSm 2Ag 3Se 5

    Science.gov (United States)

    Huang, Fu Qiang; Ibers, James A.

    2000-05-01

    Six quaternary rubidium selenides RbLn2CuSe4 (Ln=Sm, Gd, Dy), Rb1.5Ln2Cu2.5Se5 (Ln=Gd, Dy), and RbSm2Ag3Se5 have been synthesized at 1073 K with the use of a reactive flux of Rb2Se3. At 153 K all compounds contain four formula units in orthorhombic unit cells. The isostructural compounds RbLn2CuSe4 crystallize in space group Cmcm; the isostructural compounds Rb1.5Ln2Cu2.5Se5 crystallize in space group Pnnm; RbSm2Ag3Se5 crystallizes in space group Cmcm. The cells of RbLn2CuSe4 are (Ln, a, b, c (Å)): Sm, 4.1834(9), 14.308(3), 14.439(3); Gd, 4.1568(8), 14.227(3), 14.409(3); Dy, 4.1237(10), 14.083(4), 14.291(3), and the corresponding R1 indices for the refined structures are 0.023, 0.029, and 0.039. The cells of Rb1.5Ln2Cu2.5Se5 are: Gd, 16.243(3), 16.449(3), 4.0980(7); Dy, 16.120(3), 16.292(3), 4.0610(8), and the R1 indices are 0.036 and 0.043. The cell of RbSm2Ag3Se5 is 4.3223(6), 15.229(2), 17.420(3) Å and the R1 index is 0.025. All six are closely related three-dimensional tunnel structures. Their anionic frameworks are built from LnSe6 octahedra and MSe4 (M=Cu, Ag) tetrahedra. RbLn2CuSe4 contains infinite 1∞[CuSe3] chains of vertex-sharing tetrahedra; Rb1.5Ln2Cu2.5Se5 also contains infinite chains of tetrahedra; and the tunnel in RbSm2Ag3Se5 holds one Rb+ cation in a 10-membered ring consisting of six Ag-Se bonds and four Sm-Se bonds. Rb1.5Dy2Cu2.5Se5, which is paramagnetic, obeys the Curie-Weiss law and has an effective magnetic moment of 10.63(4) μB.

  10. PNBE-supported metallopolymer-type optical materials through grafting of Zn-Ln (Ln = Nd, Yb or Er) benzimidazole complex monomers with efficient NIR luminescence

    Science.gov (United States)

    Liu, Lin; Li, Hongyan; Feng, Weixu; Fu, Guorui; Lü, Xingqiang; Wong, Wai-Kwok; Jones, Richard A.

    2017-02-01

    Through the ring-opening metathesis polymerization (ROMP) of norbornene (NBE) with each of obtained allyl-containing complex monomers [Zn(L)2(Py)Ln(NO3)3] (Ln = La, 1; Nd, 2; Yb, 3; Er, 4 or Gd, 5; HL = 4-allyl-2-(1H-benzo[d]imidazol-2-yl)-6-methoxyphenol; Py = pyridine), a series of metallopolymers Poly(NBE-co-[Zn(L)2Ln(Py)(NO3)3)]) were obtained, respectively. Especially for Poly(NBE-co-2) and Poly(NBE-co-3), covalently-bonded grafting endows significantly improved physical properties including efficient NIR luminescence (ΦNdL = 0.63% and ΦYbL = 1.43%) in solid state.

  11. 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.

  12. The A-Type Ln4N2S3 Series: New Nitride Sulfides of the Light Lanthanoids (Ln = Ce–Nd

    Directory of Open Access Journals (Sweden)

    Falk Lissner

    2016-12-01

    Full Text Available The reaction of lanthanoid metal powders (Ln with sulfur and cesium azide (CsN3 as a nitrogen source in the presence of lanthanoid tribromides (LnBr3 yields lanthanoid nitride sulfides with the composition Ln4N2S3 (Ln = Ce–Nd when appropriate molar ratios of the starting material are used. Additional cesium bromide (CsBr as a flux secures quantitative conversion (7 days at 900 °C in evacuated silica tubes as well as the formation of black single crystals. All compounds crystallize isotypically with the orthorhombic crystal structure of La4N2S3 (Pnnm, Z = 2 and their structures were determined from single-crystal X-ray diffraction data (Ce4N2S3: a = 644.31(4, b = 1554.13(9, c = 404.20(3 pm; Pr4N2S3: a = 641.23(4, b = 1542.37(9, c = 400.18(3 pm; Nd4N2S3: a = 635.19(4, b = 1536.98(9, c = 397.85(3 pm. Compared to La4N2S3 the a-axes do not fulfill the expectation of the lanthanide contraction. The main feature of the crystal structure comprises N3−-centered (Ln3+4 tetrahedra arranging as pairs [N2Ln6]12+ of edge-shared [NLn4]9+ units, which are further connected via four vertices to form double chains ∞ 1{([NLn4/2]26+}. Bundled along [001] like a hexagonal rod packing, they are held together by two crystallographically different S2− anions. Two compounds of a second modification (B-type La4N2S3 and Pr4N2S3 will also be presented and discussed for comparison.

  13. Research of Testing Technology About LN82530 Serial Communication Controler%LN82530串行通讯控制器测试技术研究

    Institute of Scientific and Technical Information of China (English)

    于祥苓; 冯蕊; 唐琳

    2004-01-01

    LN82530串行通讯控制器(SCC)是一种双通道、多重协议数据通讯外围接口电路.此电路包括复杂的内部功能,可当作串行-并行,并行-串行转换器/控制器.本文对LN82530内部各功能块的测试作了详细的研究,并对其直流测试中存在的某些问题的解决作了简要的介绍.

  14. 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.

  15. Synthesis and conductivities of the garnet-related Li ion conductors, Li5Ln3Sb2O12 (Ln= La, Pr, Nd, Sm, Eu)

    OpenAIRE

    Percival, Julia; Kendrick, Emma; Slater, Peter

    2008-01-01

    In this paper the synthesis and conductivities of the garnet-related Li ion conductors, Li5Ln3Sb2O12 (Ln=La, Pr, Nd, Sm, Eu), are reported. These phases show high Li ion conductivity, similar to previously reported for the related Li5La3M2O12 (M=Nb, Ta) materials. Neutron diffraction structural studies are also reported for Li5La3Sb2O12 indicating a cubic unit cell, space group Ia-3d, with Li located in two partially occupied sites.

  16. Low-Temperature Transformations of Protonic Forms of Layered Complex Oxides HLnTiO4 and H2Ln2Ti3O10 (Ln = La, Nd

    Directory of Open Access Journals (Sweden)

    L. D. Abdulaeva

    2013-01-01

    Full Text Available In the present work protonic forms of layered n=1,3 Ruddlesden-Popper oxides HLnTiO4 and H2Ln2Ti3O10 (Ln = La, Nd were used as the starting point for soft chemistry synthesis of two series of perovskite-like compounds by acid leaching and exfoliation, promoted by vanadyl sulfate. The last route leads to the nanostructured VO2+ containing samples. Characterization by SEM, powder XRD, and TGA has been performed for the determination of the structure and composition of synthesized oxides.

  17. Mechanical Properties and Defective Effects of 316LN Stainless Steel by First-Principles Simulations

    Institute of Scientific and Technical Information of China (English)

    X.Q. Li; J.J. Zhao; J.C. Xu; X. Liu

    2011-01-01

    In current International Thermonuclear Experimental Reactor (ITER) design, the 316LN austenitic stainless steel (316LN SS) is used for first-wall/blanket structures. Thus, it is necessary to study the fundamental mechanical properties and irradiation effect of 316LN SS. A random solid solution model of Fe-Cr-Ni-Mn- Mo-Si alloy is used for describing 310LN S$. Using first-principles approaches, the elastic constants and ideal strength of the alloy were calculated. Such alloy exhibits good ductile behavior according to the theoretical values of Cauchy pressure and ratio of bulk modulus and shear modulus. Within the 256-atom supercell, inclusion of single vacancy defect further enhances the ductility of the alloy, and the existence of interstitial (Fe, H, He) atoms enhances the Young's modulus.

  18. Design and validation of the high performance and low noise CQU-DTU-LN1 airfoils

    DEFF Research Database (Denmark)

    Cheng, Jiangtao; Zhu, Wei Jun; Fischer, Andreas

    2014-01-01

    with the blade element momentum theory, the viscous-inviscid XFOIL code and an airfoil self-noise prediction model, an optimization algorithm has been developed for designing the high performance and low noise CQU-DTU-LN1 series of airfoils with targets of maximum power coefficient and low noise emission......This paper presents the design and validation of the high performance and low noise Chong Qing University and Technical University of Denmark LN1 (CQU-DTU-LN1) series of airfoils for wind turbine applications. The new design method uses target characteristics of wind turbine airfoils in the design...... emission between the CQU-DTU-LN118 airfoil and the National Advisory Committee for Aeronautics (NACA) 64618 airfoil, which is used in modern wind turbine blades, are carried out. Copyright © 2013 John Wiley & Sons, Ltd....

  19. Structurally characterized luminescent lanthanide zinc carboxylate precursors for Ln-Zn-O nanomaterials.

    Science.gov (United States)

    Boyle, Timothy J; Raymond, Rebecca; Boye, Daniel M; Ottley, Leigh Anna M; Lu, Ping

    2010-09-14

    A novel family of lanthanide zinc carboxylate compounds was synthesized, characterized (structural determination and luminescent behavior), and investigated for utility as single-source precursors to Ln-Zn-O nanoparticles. Carboxylic acids [H-ORc = H-OPc (H-O(2)CCH(CH(3))(2), H-OBc (H-O(2)CC(CH(3))(3), H-ONc (H-O(2)CCH(2)C(CH(3))(3))] were individually reacted with diethyl zinc (ZnEt(2)) to yield a set of previously unidentified zinc carboxylates: (i) [Zn(mu-ORc)(3)Zn(mu-ORc)](n) [ORc = OPc (1), ONc (2)], (ii) [(py)Zn](2)(mu-ORc)(4) [ORc = OBc (3), ONc (4), and py = pyridine], or (iii) Zn(ORc)(2)(solv)(2) [ORc/solv = OPc/py (5), O(c)Nc/H(2)O (6) (O(c)Rc = chelating)]. Introduction of lanthanide cation [Ln[N(SiMe(3))(2)](3), ZnEt(2), and HOBc in py] yielded the mixed cationic species structurally characterized as: (i) (O(c)Bc)Ln[(mu-OBc)(3)Zn(py)](2) [Ln = Pr (7), Nd (8), Sm (9)] or (ii) (py)(2)Zn(mu-OBc)(3)Ln(O(c)Bc)(2)(py) [Ln = Tb (10), Dy (11), Er (12), Y (13), Yb (14)]. Exploration of alternative starting materials [Ln(NO(3))(3).nH(2)O, Zn(O(2)CCH(3))(2), HOBc in py] led to the isolation of (NO(3)(c))Ln[(mu-OBc)(3)Zn(py)](2) [Ln = La (15), Ce (16), Pr (17), Nd (18), Sm (19), Eu (20), Gd (21), Tb (22) Dy (23), and Er (24); NO(3)(c) = chelating]. The UV-vis spectra of 7-24 revealed standard absorption spectra for the Ln cations. Representative compounds were used to generate nanoparticles from an established 1,4-butanediol-based solution precipitation route. The nanoproducts isolated adopted either a mixed zincite/lanthanum oxide (18n or 22n) or pure zincite (8n or 10n) phase dependent on NO(3) or OBc moiety. Fluorescence was not observed for any of these nanomaterials possibly due to phase separation, low crystallinity, surface traps, and/or quenching based on elevated Ln cation content.

  20. Electron spin resonance study of electron localization and dynamics in metal-molten salt solutions: comparison of M-MX and Ln-LnX sub 3 melts (M alkali metal, Ln = rare earth metal, X = halogen)

    CERN Document Server

    Terakado, O; Freyland, W

    2003-01-01

    We have studied the electron spin resonance (ESR) spectra in liquid K-KCl and M-(NaCl/KCl) sub e sub u sub t mixtures at different concentrations in salt-rich melts approaching the metal-nonmetal transition region. In both systems F-centre-like characteristics are found. Strongly exchange narrowed signals clearly indicate that fast electron exchange occurs on the picosecond timescale. In contrast, the ESR spectra of a (NdCl sub 2)(NdCl sub 3)-(LiCl/KCl) sub e sub u sub t melt are characterized by a large line width of the order of 10 sup 2 mT which decreases with increasing temperature. In this case, the g-factor and correlation time are consistent with the model of intervalence charge transfer, which is supported by recent conductivity and optical measurements. The different transport mechanisms will be discussed.

  1. Phase relationships and materials design in the Ln-Si-Al-O-N system

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Subsolidus phase relationships in the system Ln2O3-Si3N4-AlN-Al2O3, where Ln represents Nd, Sm and Dy, were summarized, with emphasis on the region involving α-sialon, β-sialon and AlN-polytypoid phases. This information is further used in designing the compatible matrix phases of sialon materials with desirable properties. Examples were provided to illustrate the advantage of such a basic approach to materials design.

  2. SYNTHESES AND STRUCTURES OF AGLNS2 (LN=SM-YB) COMPOUNDS

    NARCIS (Netherlands)

    VANDERLEE, A; VANDEBELT, R; WIEGERS, GA

    1992-01-01

    The ternary compounds AgLnS2 (Ln = Sm-Yb) have been synthesized and characterized. It has been found, in accordance with a previous study, that all compounds, except AgYbS2, are monoclinic with a almost-equal-to b almost-equal-to 7.7 angstrom, c almost-equal-to 12 angstrom and 90-degrees

  3. Heterotrimetallic coordination polymers: {Cu(II)Ln(III)Fe(III)} chains and {Ni(II)Ln(III)Fe(III)} layers: synthesis, crystal structures, and magnetic properties.

    Science.gov (United States)

    Alexandru, Maria-Gabriela; Visinescu, Diana; Andruh, Marius; Marino, Nadia; Armentano, Donatella; Cano, Joan; Lloret, Francesc; Julve, Miguel

    2015-03-27

    The use of the [Fe(III) (AA)(CN)4](-) complex anion as metalloligand towards the preformed [Cu(II) (valpn)Ln(III)](3+) or [Ni(II) (valpn)Ln(III) ](3+) heterometallic complex cations (AA=2,2'-bipyridine (bipy) and 1,10-phenathroline (phen); H2 valpn=1,3-propanediyl-bis(2-iminomethylene-6-methoxyphenol)) allowed the preparation of two families of heterotrimetallic complexes: three isostructural 1D coordination polymers of general formula {[Cu(II) (valpn)Ln(III) (H2O)3 (μ-NC)2 Fe(III) (phen)(CN)2 {(μ-NC)Fe(III) (phen)(CN)3}]NO3 ⋅7 H2O}n (Ln=Gd (1), Tb (2), and Dy (3)) and the trinuclear complex [Cu(II) (valpn)La(III) (OH2 )3 (O2 NO)(μ-NC)Fe(III) (phen)(CN)3 ]⋅NO3 ⋅H2O⋅CH3 CN (4) were obtained with the [Cu(II) (valpn)Ln(III)](3+) assembling unit, whereas three isostructural heterotrimetallic 2D networks, {[Ni(II) (valpn)Ln(III) (ONO2 )2 (H2 O)(μ-NC)3 Fe(III) (bipy)(CN)]⋅2 H2 O⋅2 CH3 CN}n (Ln=Gd (5), Tb (6), and Dy (7)) resulted with the related [Ni(II) (valpn)Ln(III) ](3+) precursor. The crystal structure of compound 4 consists of discrete heterotrimetallic complex cations, [Cu(II) (valpn)La(III) (OH2)3 (O2 NO)(μ-NC)Fe(III) (phen)(CN)3 ](+), nitrate counterions, and non-coordinate water and acetonitrile molecules. The heteroleptic {Fe(III) (bipy)(CN)4} moiety in 5-7 acts as a tris-monodentate ligand towards three {Ni(II) (valpn)Ln(III)} binuclear nodes leading to heterotrimetallic 2D networks. The ferromagnetic interaction through the diphenoxo bridge in the Cu(II)-Ln(III) (1-3) and Ni(II)-Ln(III) (5-7) units, as well as through the single cyanide bridge between the Fe(III) and either Ni(II) (5-7) or Cu(II) (4) account for the overall ferromagnetic behavior observed in 1-7. DFT-type calculations were performed to substantiate the magnetic interactions in 1, 4, and 5. Interestingly, compound 6 exhibits slow relaxation of the magnetization with maxima of the out-of-phase ac signals below 4.0 K in the lack of a dc field, the values of the pre

  4. Earth\\'s Mass Variability

    CERN Document Server

    Mawad, Ramy

    2014-01-01

    The perturbation of the Earth caused by variability of mass of Earth as additional reason with gravity of celestial bodies and shape of the Earth. The Earth eating and collecting matters from space and loss or eject matters to space through its flying in the space around the Sun. The source of the rising in the global sea level is not closed in global warming and icebergs, but the outer space is the additional important source for this rising. The Earth eats waters from space in unknown mechanism. The mass of the Earth become greater in November i.e. before transit apoapsis two months, and become latter in February i.e. after transit apoapsis to two months.

  5. Syntheses, structures, and magnetic properties of a family of heterometallic heptanuclear [Cu5Ln2] (Ln = Y(III), Lu(III), Dy(III), Ho(III), Er(III), and Yb(III)) complexes: observation of SMM behavior for the Dy(III) and Ho(III) analogues.

    Science.gov (United States)

    Chandrasekhar, Vadapalli; Dey, Atanu; Das, Sourav; Rouzières, Mathieu; Clérac, Rodolphe

    2013-03-04

    Sequential reaction of the multisite coordination ligand (LH3) with Cu(OAc)2·H2O, followed by the addition of a rare-earth(III) nitrate salt in the presence of triethylamine, afforded a series of heterometallic heptanuclear complexes containing a [Cu5Ln2] core {Ln = Y(1), Lu(2), Dy(3), Ho(4), Er(5), and Yb(6)}. Single-crystal X-ray crystallography reveals that all the complexes are dicationic species that crystallize with two nitrate anions to compensate the charge. The heptanuclear aggregates in 1-6 are centrosymmetrical complexes, with a hexagonal-like arrangement of six peripheral metal ions (two rare-earth and four copper) around a central Cu(II) situated on a crystallographic inversion center. An all-oxygen environment is found to be present around the rare-earth metal ions, which adopt a distorted square-antiprismatic geometry. Three different Cu(II) sites are present in the heptanuclear complexes: two possess a distorted octahedral coordination sphere while the remaining one displays a distorted square-pyramidal geometry. Detailed static and dynamic magnetic properties of all the complexes have been studied and revealed the single-molecule magnet behavior of the Dy(III) and Ho(III) derivatives.

  6. Syntheses, characterization, and luminescence of two lanthanide complexes [Ln2(acetate)6(H2O)4]·4H2O (Ln=Tb(1), Sm(2))

    Institute of Scientific and Technical Information of China (English)

    YU Qiongyan; ZHOU Xiuxia; LIU Maosheng; CHEN Jianqiao; ZHOU Zhengyuan; YIN Xia; CAI Yuepeng

    2008-01-01

    Two dinuclear compounds [Ln2(acetate)6(H2O)4]·4H2O (Ln=Tb(1), Sm(2)) were obtained by the hydrothermal reaction of Ln2O3 with malonic acid at 150 ℃. Both compounds were characterized by elemental analyses, infrared spectra, and single crystal X-ray diffraction. The results showed that complexes 1 and 2 were isomorphous and crystallize in triclinic space group P(-1). The coordination geometry around Ln(III) ions in the complexes 1 and 2 was a distorted tricapped trigonal prism with a nine coordination. In the crystal, the molecular organization was further stabilized by well-defined weak hydrogen bonding interactions between the neutral dinuclear molecular units that led to the formation of a three-dimensional network. The fluorescence properties of the two complexes 1 and 2 in organic solvents were also studied. The results show that the ligand acetate favored energy transfer to the emitting energy level of Tb(III) in complex 1. Some factors that influence the fluorescent intensity were also discussed in the article.

  7. Analýza modálních vlastností vertikálního synchronního generátoru

    OpenAIRE

    Kornherr, Milan

    2012-01-01

    Diplomová práce se zabývá analýzou modálních vlastností synchronního vertikálního generátoru. Cílem práce je určení vlivu jednotlivých částí generátoru na modální vlastnosti. Analyzována je kostra generátoru, rotor a celý generátor. Další část práce se zabývá analýzou různých variant uložení generátoru a také konstrukčních úprav, které vedou ke zlepšení modálních vlastností. Výpočtové modelování bylo provedeno v programu ANSYS. This Master´s thesis deals with the analysis of modal characte...

  8. Rapid microwave-assisted sol-gel preparation of Pd-substituted LnFeO3 (Ln = Y, La): phase formation and catalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Misch, Lauren M.; Birkel, Alexander; Figg, C. Adrian; Fors, Brett P.; Hawker, Craig J.; Stucky, Galen D.; Seshadri, Ram [UCSB

    2014-02-13

    We present a rapid microwave-assisted sol–gel approach to Pd-substituted LnFeO3 (Ln = Y, La) for applications in C–C coupling reactions. These materials could be prepared in household microwave ovens in less than 15 minutes of reaction time with the final materials displaying well-defined structure and morphology. Phase evolution was studied using time-dependent microwave heatings and then compared with the results obtained from thermogravimetric analyses. Materials were confirmed to be phase pure by laboratory and synchrotron X-ray diffraction. Substituted Pd is ionic as shown by the binding energy shift from X-ray photoelectron spectroscopy. The short heating periods required for phase purity allow these materials less time for sintering as compared to conventional solid state preparation methods, making relatively high surface areas achievable. These materials have been successfully used as catalyst precursor materials for C–C coupling reactions in which the active species is Pd0. Pd-substituted LnFeO3 (Ln = Y, La) provides Pd0 in solution which can be complexed by the ligand SPhos, allowing for aryl chloride coupling.

  9. Synthesis and photophysical properties of Ir~Ⅲ-Ln~Ⅲ(Ln=Nd,Yb,Er) bimetallic complexes containing bipyrimidines as bridging ligands

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Bipyrimidines have been chosen as(NN)(NN) bridging ligands for connecting metal centers.IrⅢ-LnⅢ(Ln = Nd,Yb,Er) bimetallic complexes [Ir(dfppy)2(μ-bpm)Ln(TTA)3]Cl were synthesized by using Ir(dfppy)2(bpm)Cl as the ligand coordinating to lanthanide complexes Ln(TTA)3·2H2O.The stability constants between Ir(dfppy)2(bpm)Cl and lanthanide ions were measured by fluorescence titration.The obvious quenching of visible emission from IrⅢ complex in the IrⅢ-LnⅢ(Ln = Nd,Yb,Er) bimetallic complexes indicates that energy transfer occurred from IrⅢ center to lanthanides.NIR emissions from NdⅢ,YbⅢ,and ErⅢ were obtained under the excitation of visible light by selective excitation of the IrⅢ-based chromophore.It was proven that Ir(dfppy)2(bpm)Cl as the ligand could effectively sensitize NIR emission from NdⅢ,YbⅢ,and ErⅢ.

  10. Infrared and Raman spectra of tris(dipivaloylmethanato) lanthanides, Ln(thd)3 (Ln = La, Nd, Eu, Gd, Tb, Ho, Er, Tm, Yb, Lu)

    Science.gov (United States)

    Belova, Natalya V.; Sliznev, Valery V.; Christen, Dines

    2017-03-01

    The infrared and Raman vibrational spectra of the series of solid tris(dipivaloylmethanato) lanthanides, Ln(thd)3 (Ln = La, Nd, Eu, Gd, Tb, Ho, Er, Tm, Yb, Lu), have been recorded at room temperature over wide ranges (4000-50 cm-1 and 3500-80 cm-1, respectively). The experimental spectra obtained in the present study were successfully assigned based on the quantum chemical calculations (DFT/PBE0) performed for the monomer Ln(thd)3 molecules. The experimental vibrational spectra for all complexes studied are rather similar as are the theoretical simulations. The data analysis shows that the main contributions to vibrational modes arise from the vibrations of the ligand possessing practically the same geometry for all complexes. According to the calculation results the structure of the coordination polyhedron is increasingly distorted in the series from La(thd)3 to Lu(thd)3. Although the contributions of the polyhedron vibrations in vibrational modes are not predominant, there is rise in the frequencies associated with vibrations of the coordination polyhedron LnO6 in this series. This increase has been explained by the concept of lanthanide contraction.

  11. Covalently-bonded grafting of [Ln3(Benzimidazole)4]-arrayed (Ln = Tb, Nd, Yb or Er) complex monomers into PNBE (poly(norbornene)) with highly luminous color-purity green-light or efficient NIR luminescence

    Science.gov (United States)

    Liu, Lin; Fu, Guorui; Feng, Heini; Guan, Jiaqing; Li, Fengping; Lü, Xingqiang; Wong, Wai-Kwok; Jones, Richard A.

    2017-07-01

    Within series of Ln3-grafted polymers Poly({[Ln3(L)4(NO3)6]·(NO3)·(H3O)2}-co-NBE) (Ln = La, 1; Ln = Eu, 2; Ln = Tb, 3; Ln = Nd, 4; Ln = Yb, 5; Ln = Er, 6 or Ln = Gd, 7) obtained from ring-opening metathesis polymerization (ROMP) of norbornene (NBE) with each of allyl-functionalized complex monomers {[Ln3(L)4(NO3)6]·(NO3)·(H3O)2} (HL = 4-allyl-2-(1H-benzo[d]imidazol-2-yl)-6-methoxyphenol), PNBE-assisted effective energy transfer renders Poly(3-co-NBE) Tb3+-centered highly luminous color-purity green-light with an attractive quantum yield of 87% and efficient near-infrared (NIR) luminescence (ΦNdL = 0.61%; ΦYbL = 1.47% and ΦErL = 0.03%) for Nd3+-, Yb3+- or Er3+-grafted polymers.

  12. Influence of Tuned Linker Functionality on Modulation of Magnetic Properties and Relaxation Dynamics in a Family of Six Isotypic Ln2 (Ln = Dy and Gd) Complexes.

    Science.gov (United States)

    Mukherjee, Soumya; Lu, Jingjing; Velmurugan, Gunasekaran; Singh, Shweta; Rajaraman, Gopalan; Tang, Jinkui; Ghosh, Sujit K

    2016-11-07

    A coordination complex family comprising of six new dinuclear symmetric lanthanide complexes, namely, [Ln2(Lx)2(L')2(CH3OH)2]·yG (H2Lx: three related yet distinct Schiff-base linkers; x = 1-3, according to the nomenclature of the Schiff-base linker employed herein. HL': 2,6-dimethoxyphenol. yG refers to crystallographically assigned guest solvent species in the respective complexes; y = number of solvent molecules; Ln(III) = Dy/Gd) were isolated employing a mixed-ligand strategy stemming out of a strategic variation of the functionalities introduced among the constituent Schiff-base linkers. The purposeful introduction of three diverse auxiliary groups with delicate differences in their electrostatic natures affects the local anisotropy and magnetic coupling of Ln(III) ion-environment in the ensuing Ln2 dinuclear complexes, consequentially resulting into distinctly dynamical magnetic behaviors among the investigated new-fangled family of isotypic Ln2 complexes. Among the entire family, subtle alterations in the chemical moieties render two of the Dy2 analogues to behave as single molecule magnets, while the other Dy2 congener merely exhibits slow relaxation of the magnetization. The current observation marks one of the rare paradigms, wherein magnetic behavior modulation was achieved by virtue of the omnipresent influence of subtly tuned linker functionalities among the constituent motifs of the lanthanide nanomagnets. To rationalize the observed difference in the magnetic coupling, density functional theory and ab initio calculations (CASSCF/RASSI-SO/POLY_ANISO) were performed on all six complexes. Subtle difference in the bond angles leads to difference in the J values observed for Gd2 complexes, while difference in the tunnel splitting associated with the structural alterations lead to variation in the magnetization blockade in the Dy2 complexes.

  13. Phase transformations during HLnTiO4 (Ln=La, Nd) thermolysis and photocatalytic activity of obtained compounds

    Science.gov (United States)

    Silyukov, Oleg I.; Abdulaeva, Liliia D.; Burovikhina, Alena A.; Rodionov, Ivan A.; Zvereva, Irina A.

    2015-03-01

    Layered HLnTiO4 (Ln=La, Nd) compounds belonging to Ruddlesden-Popper phases were found to form partially hydrated compounds Ln2Ti2O7·xH2O during thermal dehydration as well as defect oxides Ln2□Ti2O7 as final products. Further heating of metastable defect Ln2□Ti2O7 substances leads to the formation of pyrochlore-type oxides Ln2Ti2O7 (p), with subsequent transformation under higher temperatures to stable layered 110-type perovskites Ln2Ti2O7. The occurring structure transformations lead to an increase of photocatalytic activity in the order of HLnTiO4<Ln2Ti2O7·yH2O<Ln2□Ti2O7<Ln2Ti2O7 (p)<Ln2Ti2O7 in the reaction of hydrogen evolution from aqueous isopropanol solution.

  14. Structure and electric transport properties of LnSr2FeTiO7 (Ln = La, Nd and Gd)

    Indian Academy of Sciences (India)

    Suresh Gupta; V Singh; B L Sharma; Indu Bhushan Sharma

    2011-02-01

    Three new phases with compositions, LaSr2FeTiO7, NdSr2FeTiO7 and GdSr2FeTiO7, were prepared by the traditional ceramic method. Lazy–Pulverix analysis of the X-ray diffraction data suggests that the phases crystallize in the RP-type ( = 2) structure in the space group, 4/. The cell dimensions along the -axis decrease with decrease in size of the rare earth ions. Electrical resistivity, as a function of temperature, shows that the materials are insulators and the resistivity decreases with decrease in the size of the rare earth ion, which is attributed to increase in the three-dimensional character.

  15. Template-free synthesis and luminescent properties of hollow Ln:YOF (Ln = Eu or Er + Yb) microspheres

    OpenAIRE

    Martínez-Castro, Elisa; García-Sevillano, J.; Cussó, Fernando; Ocaña, Manuel

    2015-01-01

    © 2014 Elsevier B.V. All rights reserved. A method for the synthesis of hollow lanthanide doped yttrium oxyfluoride (YOF) spheres in the micrometer size range with cubic structure based on the pyrolysis at 600 °C of liquid aerosols generated from aqueous solutions containing the corresponding rare earth chlorides and trifluoroacetic acid has been developed. This procedure, which has been used for the first time for the synthesis of YFO based materials, is simpler and advantageous when compare...

  16. Luminescence investigations of rare earth doped lead-free borate glasses modified by MO (M = Ca, Sr, Ba)

    Energy Technology Data Exchange (ETDEWEB)

    Janek, Joanna, E-mail: janek.joanna@gmail.com; Sołtys, Marta; Żur, Lidia; Pietrasik, Ewa; Pisarska, Joanna; Pisarski, Wojciech A.

    2016-09-01

    Series of lead-free borate glasses with different oxide modifiers and lanthanide ions were prepared. The effect of oxide modifiers MO (M = Ca, Sr, Ba) on spectroscopic properties of trivalent Ln{sup 3+} (Ln = Eu, Er, Pr) were systematically investigated. Especially, the luminescence spectra of Ln{sup 3+}-doped lead-free borate glasses are presented and discussed in relation to the impact of selective components (CaO, SrO and BaO). Several spectroscopic parameters, such as the fluorescence intensity ratio R/O (Eu{sup 3+}) and measured luminescence lifetimes for the {sup 5}D{sub 0} (Eu{sup 3+}), {sup 4}I{sub 13/2} (Er{sup 3+}) and {sup 1}D{sub 2} (Pr{sup 3+}) excited states of lanthanide ions were analyzed in details. The research proved that spectroscopic properties of trivalent Ln{sup 3+} depend significantly on kind of presence oxide modifiers MO (M = Ca, Sr, Ba) in glass host matrices. - Highlights: • Luminescence of Ln{sup 3+}-doped borate glasses was presented and discussed. • Effect of glass modifiers on spectroscopic properties of rare earths was studied. • Measured luminescence lifetimes of Ln{sup 3+} (Ln = Eu, Er, Pr) were analyzed. • Luminescence intensity ratios R/O (Eu{sup 3+}) were determined.

  17. Structures and magnetic properties of double perovskites A sub 2 LnMO sub 6 and 6H-perovskites Ba sub 3 LnRu sub 2 O sub 9 (A=Sr, Ba; Ln=Y, lanthanides; M=Nb, Ta, Ru)

    CERN Document Server

    Hinatsu, Y

    2003-01-01

    This account describes the synthesis, crystal structures and magnetic properties of double perovskites A sub 2 LnMO sub 6 and 6H-perovskites Ba sub 3 LnRu sub 2 O sub 9 (A=Sr, Ba; Ln=Y, lanthanides; M=Nb, Ta, Ru). The double perovskites A sub 2 LnMO sub 6 have two kinds of cations, Ln and M, in the B site of the perovskite ABO sub 3. These cations adopt the alternative ordered arrangement. Measurements of the magnetic susceptibility, specific heat, and powder neutron diffraction showed that all of the A sub 2 LnRuO sub 6 compounds exhibited an antiferromagnetic transition at low temperatures and a complex temperature dependence of the magnetic susceptibility below their transition temperatures. In these compounds, the magnetic interaction between the Ln (4f electrons) and Ru (4d electrons) ions via the Ln-O-Ru pathway contributes greatly to their magnetic cooperative phenomena. The structural and magnetic studies for the 6H-perovskites Ba sub 3 LnRu sub 2 O sub 9 show that the Ln cations occupy the corner-sha...

  18. Phase transition characteristics and dielectric properties of rare-earth (La, Pr, Nd, Gd) doped Ba(Zr0.09Ti0.91)O-3 ceramics

    OpenAIRE

    2010-01-01

    A-site deficient rare-earth doped barium zirconate titanate (BZT) ceramics (Ba1−yLn2y/3)Zr0.09Ti0.91O3 (Ln = La, Pr, Nd, Gd) are obtained by a modified solid-state reaction method. Perovskite-like single-phase compounds were confirmed from X-ray diffraction data. Morphological analysis on sintered samples shows that the addition of rare-earth ions inhibits the growth of the grain and remarkably changes the grain morphology. The effect of rare-earth addition to BZT on phase transition and diel...

  19. Earth materials and earth dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, K; Shankland, T. [and others

    2000-11-01

    In the project ''Earth Materials and Earth Dynamics'' we linked fundamental and exploratory, experimental, theoretical, and computational research programs to shed light on the current and past states of the dynamic Earth. Our objective was to combine different geological, geochemical, geophysical, and materials science analyses with numerical techniques to illuminate active processes in the Earth. These processes include fluid-rock interactions that form and modify the lithosphere, non-linear wave attenuations in rocks that drive plate tectonics and perturb the earth's surface, dynamic recrystallization of olivine that deforms the upper mantle, development of texture in high-pressure olivine polymorphs that create anisotropic velocity regions in the convecting upper mantle and transition zone, and the intense chemical reactions between the mantle and core. We measured physical properties such as texture and nonlinear elasticity, equation of states at simultaneous pressures and temperatures, magnetic spins and bonding, chemical permeability, and thermal-chemical feedback to better characterize earth materials. We artificially generated seismic waves, numerically modeled fluid flow and transport in rock systems and modified polycrystal plasticity theory to interpret measured physical properties and integrate them into our understanding of the Earth. This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL).

  20. Some Rare Earth Metallic Organohydrides with Biindenyl as the Ligand

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ Introduction It is well known that organometallic hydrides of rare earth metals are the catalysts and reducing reagents for the catalysis polymerization of alkenes and the catalysis hydrogenation of alkenoalkynes. There are four methods for the syntheses of organometallic hydrides of rare earth metals: (1) the thermal atomization of metals, I. E. , the interaction of a rare earth metal with alkenes with a terminal alkyne; (2) the Ln-C σ bond is broken with H2; (3) metallic hydride replacement[1], I. E., NaBH4, LiA1H4 and Na can be used to react with organometallic compounds of rare earth metals; (4) the elimination ofβ-H, I. E. , in the presence of LiC1, the elimination of theβ-H of the alkyl compounds of rare earth metals gives the target product. The organohydrides of biindenyl samarium, biindenyl gadolinium and biin denyl dysprosium were obtained with NaH reduction method.

  1. Vliv sociálních sítí na komunikaci a kulturu

    OpenAIRE

    Havlíček, Lukáš

    2015-01-01

    Má bakalářská práce je zaměřena na problematiku sociálních sítí a jejich vliv na dnešní společnost. Zabývá se jejich historií od prvotních pokusů až po nejnovější globální sociání sítě. Poté práce vysvětluje základní myšlenku vedoucí k vytvoření sociálních sítí i jejich charakteristické znaky. Dále nastiňuje problémy související se snadnou dostupností a nadměrným využíváním sociálních sítí, které následně ovlivňuje lidskou společnost. Práce se věnuje vlivu sociálních sítí na jazyk, mezilidsko...

  2. Fabrication of Ln-MOFs with color-tunable photoluminescence and sensing for small molecules

    Science.gov (United States)

    Wang, Shengyan; Shan, Liang; Fan, Yong; Jia, Jia; Xu, Jianing; Wang, Li

    2017-01-01

    Three isomorphic lanthanide metal-organic frameworks (Ln-MOFs) [LnL(H2O)2]·2H2O (Ln=Tb for 1, Eu for 2, Gd for 3) have been constructed from flexible organic ligand 4-(2-carboxyphenoxy)benzene-1,3-dioic acid (H3L). They exhibit two-dimensional (2D) layered structure with the rhombus windows along the b axis. This network can be described as a shubnikov plane net with Schäfli symbol of (43)2(46.66.83). Solid state luminescent studies indicate that 1 and 2 show the characteristic red, and green emissions of the corresponding Ln3+ ions, respectively, while 3 exhibits blue emission arising from the organic ligand. Then by adjusting the relative amounts of different luminescent components into the well-defined host framework, a series of new co-doped Ln-MOF, Tb1-xEuxL (4) (x refers to the molar ratios of Eu3+ and Tb3+), with tunable luminescence have been fabricated. The luminescent color of 4 can be tuned from green to red due to the energy transfer from the Tb3+ to Eu3+ ions by changing the doping concentration of the Eu3+ ions. In addition, 2 exhibits good stability in different solvents and excellent fluorescence sensing for small molecules, especially for CH3CN and nitrobenzene.

  3. Consideration of sub-cooled LN2 circulation system for HTS power machines

    Science.gov (United States)

    Yoshida, Shigeru; Hirai, Hirokazu; Nara, N.; Nagasaka, T.; Hirokawa, M.; Okamoto, H.; Hayashi, H.; Shiohara, Y.

    2012-06-01

    We consider a sub-cooled liquid nitrogen (LN) circulation system for HTS power equipment. The planned circulation system consists of a sub-cool heat exchanger (subcooler) and a circulation pump. The sub-cooler will be connected to a neon turbo- Brayton cycle refrigerator with a cooling power of 2 kW at 65 K. Sub-cooled LN will be delivered into the sub-cooler by the pump and cooled within it. Sub-cooled LN is adequate fluid for cooling HTS power equipment, because its dielectric strength is high and it supports a large critical current. However, a possibility of LN solidification in the sub-cooler is a considerable issue. The refrigerator will produce cold neon gas of about 60 K, which is lower than the nitrogen freezing temperature of 63 K. Therefore, we designed two-stage heat exchangers which are based on a plate-fin type and a tube-intube type. Process simulations of those heat exchangers indicate that sub-cooled LN is not frozen in either sub-cooler. The plate-fin type sub-cooler is consequently adopted for its reliability and compactness. Furthermore, we found that a cooling system with a Brayton refrigerator has the same total cooling efficiency as a cooling system with a Stirling refrigerator.

  4. Pillared-layer cluster organic frameworks constructed from nanoscale Ln10 and Cu16 clusters.

    Science.gov (United States)

    Fang, Wei-Hui; Yang, Guo-Yu

    2014-06-02

    Two pillared-layer cluster organic frameworks, [Ln5(μ3-OH)4(μ-H2O)Cu8I8L11]·H2O (L = 4-pyridin-4-yl-benzoate; Ln = Dy(1), Eu(2)), have been made by employing lanthanide oxide and copper(I) halide as the source of lanthanide and transitional metal under hydrothermal condition. Compared to the pillared-layer frameworks constructed from heterometallic layers and organic pillars, these two compounds are derived from lanthanide cluster organic layers and copper(I) halide cluster motifs. Thus, there are two distinct types of inorganic metal connectors in the structure, one is hydroxo lanthanide [Ln10(μ3-OH)8](22+) (Ln10) cluster, and the other is copper(I) halide [Cu16I16] (Cu16) cluster. The rational assembly of these two inorganic connectors and organic linear linkers leads to the formation of the two complexes here. To the best of our knowledge, they appear to be the first 3D frameworks constructed from decanuclear hydroxo lanthanide clusters. From the topological point of view, these compounds represent an intriguing example of a binodal (8,14)-connected net considering the Ln10 and Cu16 connectors as the nodes, revealing that they are typical high dimensional frameworks with high connected net based on high nuclearity nodes. Furthermore, elemental analysis, IR, TGA, PXRD, and UV-vis properties are also studied.

  5. 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.

  6. Multifunctionality in bimetallic Ln(III)[W(V)(CN)8]3- (Ln = Gd, Nd) coordination helices: optical activity, luminescence, and magnetic coupling.

    Science.gov (United States)

    Chorazy, Szymon; Nakabayashi, Koji; Arczynski, Mirosław; Pełka, Robert; Ohkoshi, Shin-ichi; Sieklucka, Barbara

    2014-06-02

    Two chiral luminescent derivatives of pyridine bis(oxazoline) (Pybox), (SS/RR)-iPr-Pybox (2,6-bis[4-isopropyl-2-oxazolin-2-yl]pyridine) and (SRSR/RSRS)-Ind-Pybox (2,6-bis[8H-indeno[1,2-d]oxazolin-2-yl]pyridine), have been combined with lanthanide ions (Gd(3+), Nd(3+)) and octacyanotungstate(V) metalloligand to afford a remarkable series of eight bimetallic CN(-)-bridged coordination chains: {[Ln(III)(SS/RR-iPr-Pybox)(dmf)4]3[W(V)(CN)8]3}n ⋅dmf⋅4 H2O (Ln = Gd, 1-SS and 1-RR; Ln = Nd, 2-SS and 2-RR) and {[Ln(III)(SRSR/RSRS-Ind-Pybox)(dmf)4][W(V)(CN)8]}n⋅5 MeCN⋅4 MeOH (Ln = Gd, 3-SRSR and 3-RSRS; Ln = Nd, 4-SRSR and 4-RSRS). These materials display enantiopure structural helicity, which results in strong optical activity in the range 200-450 nm, as confirmed by natural circular dichroism (NCD) spectra and the corresponding UV/Vis absorption spectra. Under irradiation with UV light, the Gd(III)-W(V) chains show dominant ligand-based red phosphorescence, with λmax ≈660 nm for 1-(SS/RR) and 680 nm for 3-(SRSR/RSRS). The Nd(III)-W(V) chains, 2-(SS/RR) and 4-(SRSR/RSRS), exhibit near-infrared luminescence with sharp lines at 986, 1066, and 1340 nm derived from intra-f (4)F3/2 → (4)I9/2,11/2,13/2 transitions of the Nd(III) centers. This emission is realized through efficient ligand-to-metal energy transfer from the Pybox derivative to the lanthanide ion. Due to the presence of paramagnetic lanthanide(III) and [W(V)(CN)8](3-) moieties connected by cyanide bridges, 1-(SS/RR) and 3-(SRSR/RSRS) are ferrimagnetic spin chains originating from antiferromagnetic coupling between Gd(III) (SGd = 7/2) and W(V) (SW = 1/2) centers with J1-(SS) = -0.96(1) cm(-1), J1-(RR) =-0.95(1) cm(-1), J3-(SRSR) = -0.91(1) cm(-1), and J3-(RSRS) =-0.94(1) cm(-1). 2-(SS/RR) and 4-(SRSR/RSRS) display ferromagnetic coupling within their Nd(III)-NC-W(V) linkages.

  7. Syntheses and Characterizations of Cu-Ln Heterobinuclear Complexes with Schiff Base from 3-Formylsalicylic Acid and Ethylene Diamine

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Seven heterobinuclear complexes of Cu-Ln with N,N'-bis(3-carboxylsali cylidene) ethylenediamine(ES) were synthesized and characterized by elemental analysis, molar conductivity, thermogravimetry, IR and electronic spectra. The room tempeature magnetic moments show that there are basically no spin exchange interactions between the ions of Cu2+ and Ln3+ in the CuLnESCl·nH2O compounds.

  8. Role of minerals properties on leaching process of weathered crust elution-deposited rare earth ore

    Institute of Scientific and Technical Information of China (English)

    肖燕飞; 刘向生; 冯宗玉; 黄小卫; 黄莉; 陈迎迎; 吴文远

    2015-01-01

    Granite belonged to intrusive rock and volcanic was extrusive rock. There may be many differences in their degree of weathering and mineral chemical composition. The present study investigated the minerals properties and the leaching mechanism of the granitic weathered crust elution-deposited rare earth ore from Longnan Rare Earth Mine area (LN ores) and volcanic weathered crust elution-deposited rare earth ore from Liutang Rare Earth Mine area (LT ores). The X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) were used to characterize the phase of rare earth ores. The particle size distributions and main composition of the ore were also presented in this paper. The leaching mechanisms of two kinds of rare earth ores were analyzed with different kinetics models and could be described by the shrinking-core model. They were all inner diffusion-controlled leaching processes. The leaching equation of the kinetics of the LN ores could be expressed as:4 LN LN 1.096 10 2/3 0.377 8.314 0 2 3=0.1061 (1 ) Tr e tη η×−−− − −, leaching equation of kinetics of LT ores was 3 LT LT 4.640 10 2/3 0.411 8.314 0 32 3=8.33 101 (1 ) Tr e tη η×−− −×− − −. The rare earth leaching rate of LT ores was always lower in the same condition, and it would need more time and more (NH4)2SO4 consump-tion to achieve the same rare earth leaching efficiency, which would lead to more serious ammonia-nitrogen pollution. Therefore, magnesium salt was proposed as the leaching agent to eliminate ammonia-nitrogen pollution and further studies would be taken in the future.

  9. 活跃在高考中的函数f(x)=(ln x)/x

    Institute of Scientific and Technical Information of China (English)

    梅磊

    2016-01-01

    函数f(x)=ln x/x自1983年以来,已经多次出现在高考试卷中.本文就函数f(x)=ln x/x的图像和性质,及其与一组高考题的关系进行探讨,以供参考.1.函数f(x)=ln x/x的图像和性质性质1函数f(x)=ln x/x在区间(0,e)上为增函数,

  10. Two nanosized 3d-4f clusters featuring four Ln6 octahedra encapsulating a Zn4 tetrahedron.

    Science.gov (United States)

    Zheng, Xiu-Ying; Wang, Shi-Qiang; Tang, Wen; Zhuang, Gui-Lin; Kong, Xiang-Jian; Ren, Yan-Ping; Long, La-Sheng; Zheng, Lan-Sun

    2015-07-01

    Two high-nuclearity 3d-4f clusters Ln24Zn4 (Ln = Gd and Sm) featuring four Ln6 octahedra encapsulating a Zn4 tetrahedron were obtained through the self-assembly of Zn(OAc)2 and Ln(ClO4)3. Quantum Monte Carlo (QMC) simulations show the antiferromagnetic coupling between Gd(3+) ions. Studies of the magnetocaloric effect (MCE) show that the Gd24Zn4 cluster exhibits the entropy change (-ΔSm) of 31.4 J kg(-1) K(-1).

  11. Behaviour of LaAlO3+LnTiTaO6 (Ln= Ce, Pr or Nd) dielectric ceramic mixtures

    Indian Academy of Sciences (India)

    Sam Solomon

    2012-10-01

    The 0.1LaAlO3+0.9LnTiTaO6 (Ln= Ce, Pr or Nd) ceramics are prepared through solid state ceramic route. The structure of the materials is studied using X-ray diffraction analysis. The microstructure is analysed using scanning electron microscopy. The dielectric properties in the radio as well as in the microwave frequencies are measured and discussed. The photoluminescence of a representative sample is also analysed. The dielectric constant (r) and temperature coefficient of resonant frequency (f) are tailored without appreciable change in the quality factor. The measured values of r and f are compared with the corresponding predicted values. These mixtures can be made useful in optical and microwave communication.

  12. High Dielectric Constant and Low-loss Dielectric Ceramics of Sr5LnTi3Ta7O30 (Ln= La, Nd, Sm and Y)

    Institute of Scientific and Technical Information of China (English)

    TU Wenmao; CHEN Pu; PENG Xiyang; LIU Ting

    2008-01-01

    Polycrystalline Sr5LnTi3Ta7O30 (Ln=La, Nd, Sm and Y) ceramics were prepared as single-phase materials through conventional solid-state ceramics method. The structure was characterized by X-ray diffraction method and scanning electron microscopy (SEM). The dielectric properties were measured from room temperature to 400 ℃. All compounds are paraelectric phases adopting the filled tetragonal tungsten bronze (TB) structure at room temperature. At 1 MHz their dielectric constant (e) varied from 109 to 139,dielectric loss changed from 0.003 3 to 0.005 8, and the temperature coefficients of the dielectric constant (τε)moved from -710 to -880×10-6 ℃-1.

  13. Nanostructured LnBaCo2O6− (Ln = Sm, Gd with layered structure for intermediate temperature solid oxide fuel cell cathodes

    Directory of Open Access Journals (Sweden)

    Augusto E. Mejía Gómez

    2017-04-01

    Full Text Available In this work, we present the combination of two characteristics that are beneficial for solid oxide fuel cell (SOFC cathodic performance in one material. We developed and evaluated for the first time nanostructured layered perovskites of formulae LnBaCo2O6-d with Ln = Sm and Gd (SBCO and GBCO, respectively as SOFC cathodes, finding promising electrochemical properties in the intermediate temperature range. We obtained those nanostructures by using porous templates to confine the chemical reagents in regions of 200-800 nm. The performance of nanostructured SBCO and GBCO cathodes was analyzed by electrochemical impedance spectroscopy technique under different operating conditions using Gd2O3-doped CeO2 as electrolyte. We found that SBCO cathodes displayed lower area-specific resistance than GBCO ones, because bulk diffusion of oxide ions is enhanced in the former. We also found that cathodes synthesized using smaller template pores exhibited better performance.

  14. Synthesis and characterization of LnAg(WO{sub 4})(MoO{sub 4})

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Martinez, F. [Universidad Politecnica de Madrid, E.U.I.T. Industrial, Ronda de Valencia 3, 28012 Madrid (Spain)], E-mail: francisco.fernandezm@upm.es; Colon, C.; Montero, J.L.; Atanes, E. [Universidad Politecnica de Madrid, E.U.I.T. Industrial, Ronda de Valencia 3, 28012 Madrid (Spain); Rivero, C. [Universidad Politecnica de Madrid, E.T.S.I. Telecomunicaciones, Avda. Complutense s/n, Ciudad Universitaria, 28040 Madrid (Spain)

    2008-02-28

    Polycrystalline LnAg(WO{sub 4})(MoO{sub 4}) powders, with Ln = La to Lu and Y, have been obtained by ceramic method. Rietveld refinement for all compounds reveals that they present tetragonal symmetry, space group I4{sub 1}/a (No. 88), where the Ln{sup 3+}/Ag{sup +} ions are located in the 4a atomic positions, since the W/Mo are randomly distributed into 4b crystal sites. In these compounds, a and b lattice parameters take values between those corresponding to tungstate and molybdate compounds. A progressive decrease in the lattice parameters is observed in going from La to Lu derivatives as a consequence of the well-known lanthanide contraction.

  15. Effect of Ln3+ on Inhibition of Tobacco RuBPcase

    Institute of Scientific and Technical Information of China (English)

    陈为钧; 陶冶; 胡天斗; 赵贵文

    2002-01-01

    The tobacco RuBPcase was purified by the method of (NH4)2SO4 precipitation and Sephadex G-200 column chromatography. The effects of Ln3+ on inhibition of RuBPcase activity were studied. The results show that the vmax (maximum velocity) of RuBPcase does not change, but its km (Michaelis constant) increases with a ki (inhibitor constant) when increasing the concentration of Ln3+ in enzymatic reaction. It indicates that the inhibitory action of Ln3+ on tobacco RuBPcase is a model of competitive inhibition with Mg2+. The ki of La3+, Ce3+ and Gd3+ is 26.3, 34.3 and 200 μmol*L-1, respectively. Their inhibitory action on the RuBPcase is in the order of La3+>Ce3+Gd3+.

  16. Investigation of the structural properties of an extended series of lanthanide bis-hydroxychlorides Ln(OH)(2)Cl (Ln = Nd-Lu, except Pm and Sm).

    Science.gov (United States)

    Zehnder, Ralph A; Clark, David L; Scott, Brian L; Donohoe, Robert J; Palmer, Phillip D; Runde, Wolfgang H; Hobart, David E

    2010-06-07

    The trivalent lanthanide bis-hydroxychloride compounds, Ln(OH)(2)Cl, (Ln = Nd through Lu, with the exception of Pm and Sm) have been prepared by hydrothermal synthesis starting with LnCl(3).nH(2)O. These compounds were synthesized at temperatures not exceeding the melting point of the Teflon liners in the Parr autoclaves ( approximately 220 degrees C). The compounds obtained were characterized by single crystal X-ray diffraction analysis, diffuse reflectance, FT-IR, and FT-Raman spectroscopies. Most of the lanthanide(III) bis-hydroxychlorides are isostructural and generally crystallize in the monoclinic space group P2(1)/m. The bis-hydroxychlorides of the heavier lanthanide(III) atoms with smaller ionic radii also crystallize in the orthorhombic crystal system. Apparently hydrogen bonds between the OH groups and the Cl atoms connect the layers in the "c" direction. These H-bonds seem to be the driving force for the angle beta of the monoclinic complexes to decrease with decreasing ionic radius of the Ln(III) ion and also for tying the layers together more strongly. As a result of this behavior, the structure of the heavier 4f analogues significantly resembles that of their orthorhombic counterparts. The heavier lanthanide bis-hydroxychlorides preferentially crystallize in the orthorhombic modification. The IR absorbance and Raman frequencies of the hydroxide ligands correlate as a function of the central lanthanide(III) ionic radius. This observation is corroborated by X-ray diffraction (XRD) structural data. These compounds are quite insoluble in near-neutral and basic aqueous solutions, but soluble in acidic solutions. It is expected that the analogue actinide bis-hydroxychlorides exhibit similar behavior and that this may have important implications in the immobilization and safe disposal of nuclear waste.

  17. Low Temperature Preparation of Ceria Solid Solutions Doubly Doped with Rare-Earth and Alkali-Earth and Their Properties as Solid Oxide Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    任引哲; 蒋凯; 王海霞; 孟健; 苏锵

    2003-01-01

    A series of solid electrolytes, (Ce0.8Ln0.2)1-xMxO2-δ (Ln= La, Nd, Sm, Gd, M:Alkali-earth), were prepared by amorphous citrate gel method. XRD patterns indicate that a pure fluorite phase is formed at 800 ℃. The electrical conductivity and the AC impedance spectra were measured. XPS spectra show that the oxygen vacancies increase owing to the MO doping, which results in the increase of the oxygen ionic transport number and conductivity. The performance of ceria-based solid electrolyte is improved. The effects of rare-earth and alkali-earth ions on the electricity were discussed. The open-circuit voltages and maximum power density of planar solid oxide fuel cell using (Ce0.8Sm0.2)1-0.05Ca0.05O2-δ as electrolyte are 0.86 V and 33 mW*cm-2, respectively.

  18. Syntheses and crystal structures of the bromide-derivatized lanthanoid(III) ortho-oxomolybdates(VI) LnBr[MoO{sub 4}] (Ln = Pr, Nd, Sm, Gd-Lu)

    Energy Technology Data Exchange (ETDEWEB)

    Schustereit, Tanja; Henning, Harald; Schleid, Thomas; Hartenbach, Ingo [Stuttgart Univ. (Germany). Inst. for Inorganic Chemistry

    2013-05-15

    The lanthanoid(III) bromide ortho-oxomolybdates(VI) LnBr[MoO{sub 4}] (Ln = Pr, Nd, Sm, Gd-Lu) crystallize triclinically in the space group P anti 1 (a = 686-689, b = 713-741, c = 1066-1121 pm, {alpha} = 103-106, {beta} = 107-108, {gamma} = 92-95 ) with Z = 4. The crystal structure contains two crystallographically distinguishable Ln{sup 3+} cations, each one with a coordination number of seven plus one. (Ln1){sup 3+} is surrounded by three bromide and four plus one oxide anions, while for (Ln2{sup )3+} just one bromide and six plus one oxide anions belong to the coordination sphere. Considering the smallest lanthanoids, however, the distances to the farthest anions increase so much that their contribution to the coordination spheres becomes negligible in both cases. The polyhedra around (Ln1){sup 3+} are connected to each other via common edges, which consist of two crystallographically identical Br{sup -} anions (Br1). Furthermore, the common structure of the LnBr[MoO{sub 4}] series contains two crystallographically different, discrete [MoO{sub 4}]{sup 2-} ortho-oxomolybdate(VI) tetrahedra. Two plus one oxygen atoms of each [(Mo1)O{sub 4}]{sup 2-} unit are used to interconnect the polyhedra around (Ln1){sup 3+} and (Ln2){sup 3+} together with one Br{sup -} anion (Br2). The connection between two polyhedra around (Ln2){sup 3+} is generated exclusively by two plus one oxygen atoms of two [(Mo2)O{sub 4}]{sup 2-} anions. The complete structural arrangement can be considered as a bundle of primitively packed {sub {infinity}}{sup 1}{l_brace}LnBr[MoO{sub 4}]{r_brace} chains with two alternating motifs of linkage, which are running parallel along [012]. (orig.)

  19. 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.

  20. A two-step model for Langerhans cell migration to skin-draining LN

    OpenAIRE

    2008-01-01

    Although the role of Langerhans cells (LC) in skin immune responses is still a matter of debate, it is known that LC require the chemokine receptor CCR7 for migrating to skin-draining LN. A report in the current issue of the European Journal of Immunology unfolds some of the intricacies of LC migration, showing that LC need CXCR4, but not CCR7, for their migration from the epidermis to the dermis. Thus, LC migration to skin-draining LN occurs in two distinct phases: a first step from the epid...

  1. Infrared detector Dewars - Increased LN2 hold time and vacuum jacket life spans

    Science.gov (United States)

    Jennings, D. E.; Boyd, W. J.; Blass, W. E.

    1976-01-01

    IR detector Dewars commonly suffer from shorter than desired LN2 hold times and insulation jacket vacuum corruption over relatively short time periods. In an attempt to solve this problem for a 9144 detector Dewar, small 1 liter/s appendage ion pumps were selected for continuous pumping of the vacuum jackets. This procedure extended LN2 hold times from 20 to 60 h and virtually eliminated vacuum jacket corruption. Thus the detector systems are usable continuously over periods of 6 months or more.

  2. Effect of the ion force on the stability constants of the complexes LnCl{sup 2+} and LnCl{sub 2}{sup +} of Europium and Lutetium; Efecto de la fuerza ionica sobre las constantes de estabilidad de los complejos LnCl{sup 2+} y LnCl{sub 2}{sup +} de Europium y Lutetium

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez R, E.; Jimenez R, M.; Solache R, M. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2004-07-01

    A study is presented on the determination of the constants of stability of those complex LnCI{sup 3-n}{sub n} (where Ln = Eu{sup 3+} and Lu{sup 3+} and n = 1 and 2), by means of a method of extraction with solvent, to constant temperature (303 K) and in means of high ionic force (1- 3M H CI/HCIO{sub 4}). It is also presented the application of the theory of the specific interaction of ions (SIT) of Bronsted-Guggenheim-Scatchard for the extrapolation of the values to infinite dilution. (Author)

  3. Validation of the CQU-DTU-LN1 series of airfoils

    DEFF Research Database (Denmark)

    Shen, Wen Zhong; Zhu, Wei Jun; Fischer, Andreas

    2014-01-01

    The CQU-DTU-LN1 series of airfoils were designed with an objective of high lift and low noise emission. In the design process, the aerodynamic performance is obtained using XFOIL while noise emission is obtained with the BPM model. In this paper we present some validations of the designed CQU......, the designed Cl and Cl/Cd agrees well with the experiment and are in general higher than those of the NACA airfoil. For the acoustic features, the noise emission of the LN118 airfoil is compared with the acoustic measurements and that of the NACA airfoil. Comparisons show that the BPM model can predict...

  4. Truncated Moments of Nonsinglet Parton Distributions in the double logarithmic $ln^2x$ approximation

    CERN Document Server

    Kotlorz, D

    2004-01-01

    The method of truncated Mellin moments in a solving QCD evolution equations of the nonsinglet structure functions $F_2^{NS}(x,Q^2)$ and $g_1^{NS}(x,Q^2)$ is presented. All calculations are performed within double logarithmic $ln^2x$ approximation. An equation for truncated moments which incorporates $ln^2x$ effects is formulated and solved for the unintegrated structure function $f^{NS}(x,Q^2)$. The contribution to the Bjorken sum rule coming from the region of very small $x$ is quantified. Further possible improvement of this approach is also discussed.

  5. Syntheses,structures and properties of five chiral quaternary sulfides,AlxLn3(SiyAl1-γ)S7 (Ln=Y,Gd,Dy) and In0.33Sm3SiS7

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Five new quaternary isostructural rare-earth sulfides, Al0.57Gd3(Si0.27Al0.73)S7 (1), Al0.55Dy3(Si0.34Al0.66)S7 (2), Al0.50Y3(Si0.50Al0.50)S7 (3), Al0.44Gd3(Si0.70Al0.30)S7 (4) and In0.33Sm3SiS7 (5), have been synthesized by facile solid-state reactions. They crystallize in the 3-D ALn3EQ7 structure type in the hexagonal chiral space group P63. The structures feature a 3-D host framework constructed by Ln-S bicapped trigonal prisms, in which the octahedral and tetrahedral interspaces are occupied by A and E atoms, respectively. The investigation of optical and magnetic properties of 4 indicates that it is a semiconductor and behaves antiferromagnetic-like interaction.

  6. Snowball Earth

    OpenAIRE

    2016-01-01

    In the ongoing quest to better understand where life may exist elsewhere in the Universe, important lessons may be gained from our own planet. In particular, much can be learned from planetary glaciation events that Earth suffered ∼600 million years ago, so-called `Snowball Earth' episodes. I begin with an overview of how the climate works. This helps to explain how the ice-albedo feedback effect can destabilise a planet's climate. The process relies on lower temperatures causing more ice to ...

  7. Digital Earth - A sustainable Earth

    Science.gov (United States)

    Mahavir

    2014-02-01

    All life, particularly human, cannot be sustainable, unless complimented with shelter, poverty reduction, provision of basic infrastructure and services, equal opportunities and social justice. Yet, in the context of cities, it is believed that they can accommodate more and more people, endlessly, regardless to their carrying capacity and increasing ecological footprint. The 'inclusion', for bringing more and more people in the purview of development is often limited to social and economic inclusion rather than spatial and ecological inclusion. Economic investment decisions are also not always supported with spatial planning decisions. Most planning for a sustainable Earth, be at a level of rural settlement, city, region, national or Global, fail on the capacity and capability fronts. In India, for example, out of some 8,000 towns and cities, Master Plans exist for only about 1,800. A chapter on sustainability or environment is neither statutorily compulsory nor a norm for these Master Plans. Geospatial technologies including Remote Sensing, GIS, Indian National Spatial Data Infrastructure (NSDI), Indian National Urban Information Systems (NUIS), Indian Environmental Information System (ENVIS), and Indian National GIS (NGIS), etc. have potential to map, analyse, visualize and take sustainable developmental decisions based on participatory social, economic and social inclusion. Sustainable Earth, at all scales, is a logical and natural outcome of a digitally mapped, conceived and planned Earth. Digital Earth, in fact, itself offers a platform to dovetail the ecological, social and economic considerations in transforming it into a sustainable Earth.

  8. Ln3Pb3(IO3)13(mu3-O) (Ln = La-Nd): new types of second-order nonlinear optical materials containing two types of lone pair cations.

    Science.gov (United States)

    Hu, Ting; Qin, Li; Kong, Fang; Zhou, Yong; Mao, Jiang-Gao

    2009-03-02

    Hydrothermal reactions of lanthanide oxide, lead chloride, I(2)O(5), and H(2)O at 200 degrees C led to four novel quaternary compounds, namely, Ln(3)Pb(3)(IO(3))(13)(mu(3)-O) (Ln = La-Nd). They are isostructural, and their structures feature a complicated 3D network composed of LaO(9) and PbO(6) polyhedra interconnected by asymmetric IO(3) groups. Ln(3)Pb(3)(IO(3))(13)(mu(3)-O) (Ln = La, Pr, Nd) display moderate second harmonic generation efficiencies of about 2.0, 1.0, and 0.8 times the value of KH(2)PO(4), respectively. These compounds are thermally stable up to 520 degrees C. Luminescence measurements indicate that Ln(3)Pb(3)(IO(3))(13)(mu(3)-O) (Ln = Ce, Pr, Nd) exhibit strong emission bands in the visible or near IR region. Magnetic studies indicate that there exist significant antiferromagnetic interactions between magnetic centers in Ln(3)Pb(3)(IO(3))(13)(mu(3)-O) (Ln = Pr, Nd).

  9. Crystal structure and properties of complexes [Ln(Gly)4Im·(ClO4)4]n (Ln:Nd, Sm) constructed from eight-coordination containing square antiprism

    Science.gov (United States)

    Pan, Lu; Gao, Xiao-han; Lv, Xue-chuan; Tan, Zhi-cheng; Cao, Hui

    2016-08-01

    Two eight-coordination containing square antiprism polyhedra, [Ln(Gly)4Im·(ClO4)4]n (Ln:Nd, Sm) were synthesized through the self-assembly of Ln3+ (Ln:Nd, Sm) ions, glycine and imidazole in aqueous solution and characterized by X-ray single crystal diffraction. Both of the complexes crystallized in the C2/c space group. In the cluster, each Ln3+ ions was eight-coordination by eight oxygen atoms of the glycine. The coordination sphere of each Ln3+ ions could be described as a distorted square antiprism. Two central Ln3+ ions were connected by four bridging carboxyl groups from four glycine molecules. The Ln-O bond distances were related to the coordination geometries of the ligands. The complexes had two special solid-solid phase transitions at 224 K and 248 K, which were interpreted as a freezing-in phenomenon of the reorientational motion of perchlorate ions ClO4- and the orientational order/disorder process of ClO4- ions. The decomposition mechanism of the complexes was deduced to be three stages from 300 to 700 K. The fluorescent excitation and emission spectra showed that the complexes had strong fluorescent property.

  10. Synthesis, structures,thermal and magnetic properties of a series of lanthanide [Ln=Sm, Gd, Er, Yb] complexes with 4-quinolineacarboxylate

    Institute of Scientific and Technical Information of China (English)

    GAO Qian; XIE Yabo; ZHANG Chong; SUN Jihong

    2009-01-01

    A series of lanthanide binuclear complexes, [Ln2(L)6(H2O)4]·2H2O (Ln=Sm(III), Gd(III), Er(III), Yb(III), HL=4-quinolineacarboxylic acid, were synthesized by reactions of corresponding rare earth salts with 4-quinolineacarboxylic acid at room temperature and were characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. X-ray diffraction analyses showed that they exhibited the same binuclear architecture and crystallized in monoclinic system and P21/c space group. In four complexes, each metal center adopted nine-coordinated mode coordinated by nine O atoms from two H2O molecules and three carboxyls of three ligands, and HL showed three different coordination modes. The variable-temperature magnetic susceptibility showed that complex [Gd2(L)6(H2O)4]·2H2O performed very weak antiferromagnetic property at low temperature and exchange was almost paramagnetic at high temperature. Complexes [Er2(L)6(H2O)4]·2H2O and [Yb2(L)6(H2O)4]·2H2O performed dominating antiferromagnetic coupling.

  11. Controlled Isotropic and Anisotropic Shell Growth in β-NaLnF4 Nanocrystals Induced by Precursor Injection Rate.

    Science.gov (United States)

    Fischer, Stefan; Swabeck, Joseph K; Alivisatos, A Paul

    2017-09-06

    Precise morphology and composition control is vital for designing multifunctional lanthanide-doped core/shell nanocrystals. Herein, we report controlled isotropic and anisotropic shell growth techniques in hexagonal sodium rare-earth tetrafluoride (β-NaLnF4) nanocrystals by exploiting the kinetics of the shell growth. A drastic change of the shell morphology was observed by changing the injection rate of the shell precursors while keeping all other reaction conditions constant. We obtained isotropic shell growth for fast sequential injection and a preferred growth of the shell layers along the crystal's c-axis [001] for slow dropwise injection. Using this slow shell growth technique, we have grown rod-like shells around different almost spherical core nanocrystals. Bright and efficient upconversion was measured for both isotropic and rod-like shells around β-NaYF4 nanocrystals doped with Yb(3+)/Er(3+) and Yb(3+)/Tm(3+). Photoluminescence upconversion quantum yield and lifetime measurements reveal the high quality of the core/shell nanocrystal. Furthermore, multishell rod-like nanostructures have been prepared with optically active cores and tips separated by an inert intermediate shell layer. The controlled anisotropic shell growth allows the design of new core/multishell nanostructures and enables independent investigations of the chemistry and physics of different nanocrystal facets.

  12. Dissociation of diglycolamide complexes of Ln3+ (Ln = La-Lu) and An3+ (An = Pu, Am, Cm): redox chemistry of 4f and 5f elements in the gas phase parallels solution behavior.

    Science.gov (United States)

    Gong, Yu; Tian, Guoxin; Rao, Linfeng; Gibson, John K

    2014-11-17

    Tripositive lanthanide and actinide ions, Ln(3+) (Ln = La-Lu) and An(3+) (An = Pu, Am, Cm), were transferred from solution to gas by electrospray ionization as Ln(L)3(3+) and An(L)3(3+) complexes, where L = tetramethyl-3-oxa-glutaramide (TMOGA). The fragmentation chemistry of the complexes was examined by collision-induced and electron transfer dissociation (CID and ETD). Protonated TMOGA, HL(+), and Ln(L)(L-H)(2+) are the major products upon CID of La(L)3(3+), Ce(L)3(3+), and Pr(L)3(3+), while Ln(L)2(3+) is increasingly pronounced beyond Pr. A C-Oether bond cleavage product appears upon CID of all Ln(L)3(3+); only for Eu(L)3(3+) is the divalent complex, Eu(L)2(2+), dominant. The CID patterns of Pu(L)3(3+), Am(L)3(3+), and Cm(L)3(3+) are similar to those of the Ln(L)3(3+) for the late Ln. A striking exception is the appearance of Pu(IV) products upon CID of Pu(L)3(3+), in accord with the relatively low Pu(IV)/Pu(III) reduction potential in solution. Minor divalent Ln(L)2(2+) and An(L)2(2+) were produced for all Ln and An; with the exception of Eu(L)2(2+) these complexes form adducts with O2, presumably producing superoxides in which the trivalent oxidation state is recovered. ETD of Ln(L)3(3+) and An(L)3(3+) reveals behavior which parallels that of the Ln(3+) and An(3+) ions in solution. A C-Oether bond cleavage product, in which the trivalent oxidation state is preserved, appeared for all complexes; charge reduction products, Ln(L)2(2+) and Ln(L)3(2+), appear only for Sm, Eu, and Yb, which have stable divalent oxidation states. Both CID and ETD reveal chemistry that reflects the condensed-phase redox behavior of the 4f and 5f elements.

  13. Phase transformations during HLnTiO{sub 4} (Ln=La, Nd) thermolysis and photocatalytic activity of obtained compounds

    Energy Technology Data Exchange (ETDEWEB)

    Silyukov, Oleg I., E-mail: olegsilyukov@yandex.ru; Abdulaeva, Liliia D.; Burovikhina, Alena A.; Rodionov, Ivan A.; Zvereva, Irina A.

    2015-03-15

    Layered HLnTiO{sub 4} (Ln=La, Nd) compounds belonging to Ruddlesden–Popper phases were found to form partially hydrated compounds Ln{sub 2}Ti{sub 2}O{sub 7}·xH{sub 2}O during thermal dehydration as well as defect oxides Ln{sub 2}□Ti{sub 2}O{sub 7} as final products. Further heating of metastable defect Ln{sub 2}□Ti{sub 2}O{sub 7} substances leads to the formation of pyrochlore-type oxides Ln{sub 2}Ti{sub 2}O{sub 7} {sub (p)}, with subsequent transformation under higher temperatures to stable layered 110-type perovskites Ln{sub 2}Ti{sub 2}O{sub 7}. The occurring structure transformations lead to an increase of photocatalytic activity in the order of HLnTiO{sub 4}<Ln{sub 2}Ti{sub 2}O{sub 7}·yH{sub 2}O<Ln{sub 2}□Ti{sub 2}O{sub 7}<Ln{sub 2}Ti{sub 2}O{sub 7} {sub (p)}<Ln{sub 2}Ti{sub 2}O{sub 7} in the reaction of hydrogen evolution from aqueous isopropanol solution. - Graphical abstract: Layered HLnTiO{sub 4} (Ln=La, Nd) compounds form partially hydrated Ln{sub 2}Ti{sub 2}O{sub 7}·xH{sub 2}O compounds during thermal dehydration, further heating results to the formation to defect oxides Ln{sub 2}□Ti{sub 2}O{sub 7}, pyrochlor-type oxides Ln{sub 2}Ti{sub 2}O{sub 7} {sub (p)}, with subsequent transformation to layered 110-type perovskites Ln{sub 2}Ti{sub 2}O{sub 7}. Structure transformations lead to an increase of photocatalytic activity in the order of HLnTiO{sub 4}<Ln{sub 2}Ti{sub 2}O{sub 7}·yH{sub 2}O<Ln{sub 2}□Ti{sub 2}O{sub 7}<Ln{sub 2}Ti{sub 2}O{sub 7} {sub (p)}<Ln{sub 2}Ti{sub 2}O{sub 7}. - Highlights: • We studied dehydration and further thermolysis of HLnTiO{sub 4} (Ln=La, Nd) compounds. • XRD, STA and solid state IR studies were carried out. • A new series of metastable Ln{sub 2}Ti{sub 2}O{sub 7}·yH{sub 2}O compounds was obtained. • We examined the photocatalytic activity of all obtained compounds. The hydrogen evolution rate increased in the course of the structure changes during thermolysis.

  14. Rare-earth metal hydrides supported by silicon-bridged boratabenzene fluorenyl ligands: synthesis, structure and reactivity.

    Science.gov (United States)

    Wang, Chunhong; Xiang, Li; Leng, Xuebing; Chen, Yaofeng

    2017-01-24

    The reactions of rare-earth metal benzyl complexes supported by silicon-bridged boratabenzene fluorenyl ligands with PhSiH3 in toluene gave the corresponding dinuclear hydrides [{μ-[Me2Si(C13H8)(C5H4BNEt2)]}Ln(μ-H)(THF)]2 (3-Ln; Ln = La, Nd, Gd), wherein the rare-earth metal ions are linked by both silicon-bridged boratabenzene fluorenyl ligands and hydrido ligands. The reactivity of these hydrides toward unsaturated substrates was studied. Among these, alkynides [{μ-[Me2Si(C13H8)(C5H4BNEt2)]}Ln(μ-CCPh)]2 (4-Ln; Ln = La, Nd) were obtained via the σ-bond metathesis reaction, when 3-Ln (Ln = La, Nd) was treated with phenylacetylene. While reacting with 3-hexyne, the mono-addition product [{μ-[Me2Si(C13H8)(C5H4BNEt2)]}Ln]2(μ-H)[μ-C(Et)[double bond, length as m-dash]C(H)Et] (5-Ln; Ln = La, Nd) was formed. Further investigations on the reactivity of 3-La displayed that benzonitrile and tert-butyl isonitrile readily inserted into the La-H bonds, affording an azomethine complex [{μ-[Me2Si(C13H8)(C5H4BNEt2)]}La{μ-N[double bond, length as m-dash]C(H)Ph}]2 (6-La) and an N-tert-butylformimidoyl complex [{μ-[Me2Si(C13H8)(C5H4BNEt2)]}La{μ,η(2)-C(H)[double bond, length as m-dash]N(t)Bu}]2 (7-La), respectively. The reaction with N,N'-diisopropylcarbodiimide at room temperature or at 75 °C gave a dimeric complex [{μ-[Me2Si(C13H8)(C5H4BNEt2)]}La]2(μ-H)[μ-N((i)Pr)CHN((i)Pr)] (8-La) or a monomeric complex [Me2Si(C13H8)(C5H4BNEt2)]La[N((i)Pr)CHN((i)Pr)] (9-La), respectively.

  15. Anion dependent self-assembly of 56-metal Cd-Ln nanoclusters with enhanced near-infrared luminescence properties

    Science.gov (United States)

    Yang, Xiaoping; Schipper, Desmond; Zhang, Lijie; Yang, Keqin; Huang, Shaoming; Jiang, Jijun; Su, Chengyong; Jones, Richard A.

    2014-08-01

    Two series of Cd-Ln clusters: nano-drum [Ln8Cd24L12(OAc)48] and nano-double-drum [Ln12Cd44L20Cl30(OAc)54] (Ln = Nd and Yb) were prepared using a flexible Schiff base ligand bearing two aryl-Br groups. Chloride (Cl-) ions, together with the interactions of Br with other electronegative atoms, play a key role in the formation of the nano-double-drums. The structures were studied by TEM and photophysical properties were determined.Two series of Cd-Ln clusters: nano-drum [Ln8Cd24L12(OAc)48] and nano-double-drum [Ln12Cd44L20Cl30(OAc)54] (Ln = Nd and Yb) were prepared using a flexible Schiff base ligand bearing two aryl-Br groups. Chloride (Cl-) ions, together with the interactions of Br with other electronegative atoms, play a key role in the formation of the nano-double-drums. The structures were studied by TEM and photophysical properties were determined. Electronic supplementary information (ESI) available: Full experimental and characterization details for 1-4. CCDC 972369-972372. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4nr03075c

  16. Positive Integer Solutions of the Diophantine Equation $x^2 - L_n xy + (-1)^n y^2 = ± 5^r$

    Indian Academy of Sciences (India)

    Refik Keskin; Zafer Şiar

    2014-08-01

    In this paper, we consider the equation $x^2-L_n xy+(-1)^n y^2=± 5^r$ and determine the values of for which the equation has positive integer solutions and . Moreover, we give all positive integer solutions of the equation $x^2-L_n xy+(-1)^n y^2=± 5^r$ when the equation has positive integer solutions.

  17. 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.

  18. Ln3GaS6 (Ln = Dy, Y): new infrared nonlinear optical materials with high laser induced damage thresholds.

    Science.gov (United States)

    Zhang, Ming-Jian; Li, Bing-Xuan; Liu, Bin-Wen; Fan, Yu-Hang; Li, Xiao-Guo; Zeng, Hi-Yi; Guo, Guo-Cong

    2013-10-21

    Two new ternary rare earth chalcogenides, Dy3GaS6 (1) and Y3GaS6 (2), are reported here. They both crystallize in the orthorhombic space group Cmc21 (no. 36). Both are synthesized in pure phase and show phase-matchable second harmonic generation (SHG) of about 0.2 and 0.5 times, respectively for 1 and 2, as strong as that of KTiOPO4 (KTP) based on the powder SHG measurement at the wavelength of 1910 nm. They possess high powder laser induced damage thresholds (LIDTs), respectively, about 14 and 18 times that of AgGaS2 (AGS) based on the powder LIDT measurements under 1064 nm laser irradiation. They both exhibit wide transparency in the IR region (2.5–25 μm). It is believed that the title compounds are new candidates for nonlinear optical (NLO) materials in the IR region. To gain further insights into the NLO and LIDT properties of 1 and 2, the calculations of second-order NLO susceptibility and lattice energy density (LED) were also performed to explain their SHG efficiencies and high LIDTs.

  19. Template-free synthesis and luminescent properties of hollow Ln:YOF (Ln = Eu or Er + Yb) microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Castro, E. [Instituto de Ciencia de Materiales de Sevilla (CSIC-US), Americo Vespucio 49, Isla de La Cartuja, 41092 Sevilla (Spain); García-Sevillano, J.; Cussó, F. [Dpto. Física de Materiales, C-04, Universidad Autónoma de Madrid, Avda. Francisco Tomás y Valiente, 7, 28049 Madrid (Spain); Ocaña, M., E-mail: mjurado@icmse.csic.es [Instituto de Ciencia de Materiales de Sevilla (CSIC-US), Americo Vespucio 49, Isla de La Cartuja, 41092 Sevilla (Spain)

    2015-01-15

    Highlights: • Hollow lanthanide doped YOF spheres have been synthesised through a template-free procedure. • Strong red emissions are observed for Eu-doped spheres under UV illumination. • Concentration quenching of luminescence takes place in the spheres at very high Eu doping levels. • Bright red emission is observed for Er, Yb codoped spheres, making this matrix advantageous for biomedical imaging. - Abstract: A method for the synthesis of hollow lanthanide doped yttrium oxyfluoride (YOF) spheres in the micrometer size range with cubic structure based on the pyrolysis at 600 °C of liquid aerosols generated from aqueous solutions containing the corresponding rare earth chlorides and trifluoroacetic acid has been developed. This procedure, which has been used for the first time for the synthesis of YFO based materials, is simpler and advantageous when compared with other methods usually employed for the production of hollow spheres since it does not require the use of sacrificial templates. In addition, it is continuous, which is desirable because of practical reasons. The procedure is also suitable for doping the YOF spheres with europium cations resulting in down converting red phosphors when activated with UV light, or for co-doping with both Er{sup 3+} and Yb{sup 3+} giving rise to up-converting phosphors, which emit intense red light under near infrared (NIR) irradiation. Because of their optical properties and hollow architecture, the developed materials may find applications in optoelectronic devices and biotechnology.

  20. Transitory and steady analysis of grounding structures using the LN-FDTD method

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Rodrigo Melo e Silva de; Souza Sobrinho, Carlos Leonidas da S. [Federal University of Para (UFPA), Belem, PA (Brazil). Electrical and Computer Engineering Dept.], Emails: rodrigo@lane.ufpa.br, leonidas@ufpa.br

    2007-07-01

    This work presents an overview of the LN-FDTD method (FDTD in local and non orthogonal coordinate system) to solve Maxwell's Equations. This method has been used to simulate curved grounding structures. Results are obtained by employing the presented methodology and they are compared to reference equations available in literature. (author)

  1. Orthopositronium lifetime. Analytic results in O ({alpha}) and O ({alpha}{sup 3} ln {alpha})

    Energy Technology Data Exchange (ETDEWEB)

    Kniehl, B.A.; Kotikov, A.V.; Veretin, O.L. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

    2008-06-15

    We present the O({alpha}) and O({alpha}{sup 3}ln {alpha}) corrections to the total decay width of orthopositronium in closed analytic form, in terms of basic transcendental numbers, which can be evaluated numerically to arbitrary precision. (orig.)

  2. Microstructure Evolution of Multi-Heat Forging and Numerical Simulation for 316LN Steel

    Directory of Open Access Journals (Sweden)

    Duan Xing-Wang

    2014-02-01

    Full Text Available Microstructure evolution has been studied by multi-heat forging experiments and numerical simulation in order to determine the reasonable forging technology of 316 LN steel. The microstructure evolution models were obtained by hot compressive tests and heat treatment tests of 316 LN steels. The one-heat and three-heat upsetting experiments were carried on. Meanwhile, the corresponding numerical simulations were performed. The results show that, the grain uniformity of three-heat upsetting is much better that of one-heat upsetting. The average grain size of three-heat upsetting is smaller than that of one-heat upsetting. So, the forging technology of multi-heat and little deformation should be adopted for 316 LN steel forging. By comparing experimental average grain sizes with simulated average grain sizes for three-heat upsetting, it is found that the simulated values are in agreement with experimental values, which shows that the numerical simulation can be employed to predict the forging microstructure evolution of 316 LN steel.

  3. Ball Indentation Studies on the Effect of Nitrogen on the Tensile Properties of 316LN SS

    Science.gov (United States)

    Mathew, M. D.; Ganesh Kumar, J.; Ganesan, V.; Laha, K.

    2015-12-01

    Type 316L(N) stainless steel (SS) containing 0.02-0.03 wt% carbon and 0.06-0.08 wt% nitrogen is used as the major structural material for the components of fast reactors. Research is underway to improve the high-temperature mechanical properties of 316LN SS by increasing the nitrogen content in the steel above the level of 0.08 wt%. In this investigation, ball indentation (BI) technique was used to evaluate the effect of nitrogen content on the tensile properties of 316LN SS. BI tests were conducted on four different heats of 316LN SS containing 0.07, 0.11, 0.14 and 0.22 wt% nitrogen in the temperature range 300-923 K. The tensile properties such as yield strength and ultimate tensile strength increased with increase in nitrogen content at all the investigated temperatures. These results were consistent with the corresponding uniaxial tensile test results. These studies showed that BI technique can be used to optimize the chemical composition during alloy development by evaluating tensile properties with minimum volume of material.

  4. Nanomaterial size distribution analysis via liquid nebulization coupled with ion mobility spectrometry (LN-IMS).

    Science.gov (United States)

    Jeon, Seongho; Oberreit, Derek R; Van Schooneveld, Gary; Hogan, Christopher J

    2016-02-21

    We apply liquid nebulization (LN) in series with ion mobility spectrometry (IMS, using a differential mobility analyzer coupled to a condensation particle counter) to measure the size distribution functions (the number concentration per unit log diameter) of gold nanospheres in the 5-30 nm range, 70 nm × 11.7 nm gold nanorods, and albumin proteins originally in aqueous suspensions. In prior studies, IMS measurements have only been carried out for colloidal nanoparticles in this size range using electrosprays for aerosolization, as traditional nebulizers produce supermicrometer droplets which leave residue particles from non-volatile species. Residue particles mask the size distribution of the particles of interest. Uniquely, the LN employed in this study uses both online dilution (with dilution factors of up to 10(4)) with ultra-high purity water and a ball-impactor to remove droplets larger than 500 nm in diameter. This combination enables hydrosol-to-aerosol conversion preserving the size and morphology of particles, and also enables higher non-volatile residue tolerance than electrospray based aerosolization. Through LN-IMS measurements we show that the size distribution functions of narrowly distributed but similarly sized particles can be distinguished from one another, which is not possible with Nanoparticle Tracking Analysis in the sub-30 nm size range. Through comparison to electron microscopy measurements, we find that the size distribution functions inferred via LN-IMS measurements correspond to the particle sizes coated by surfactants, i.e. as they persist in colloidal suspensions. Finally, we show that the gas phase particle concentrations inferred from IMS size distribution functions are functions of only of the liquid phase particle concentration, and are independent of particle size, shape, and chemical composition. Therefore LN-IMS enables characterization of the size, yield, and polydispersity of sub-30 nm particles.

  5. Synthesis and Characterization of [(C5H4SiMe2tBu)2Ln((-SnBu)]2 (Ln = Y, Er)1

    Institute of Scientific and Technical Information of China (English)

    LI Yan-Rong; ZHANG Zheng-Xing; CHEN Zhen-Xia; LIU Rui-Ting; ZHOU Xi-Geng

    2008-01-01

    (C5H4SiMe2tBu)2LnnBu reacted with 1 equiv. of elemental sulfur in toluene at ambient temperature to yield the corresponding lanthanocene thiolates [(C5H4SiMe2tBu)2Ln(m-SnBu)]2 (Ln = Y (1), Er (2)). Complexes 1 and 2 have been characterized by elemental analysis, IR, mass spectros- copy and X-ray single-crystal diffraction analysis. Both complexes are of monoclinic with space group P21/c, formula C52H94S2Si4Y2 1 (C52H94S2Si4Er2 2) Mr = 1073.57 (1230.27), a = 8.495(2) (8.41(2)), b = 26.913(8) (26.67(7)), c = 13.756(4) (13.68(4)) (A), α = 90(90), β = 101.184(5) (101.57(4)), γ = 90 (90)°, V = 3085.1(15) (3007(14))(A)3, Dc = 1.156 (1.359) g·cm-3, Z = 2 (2), F(000) = 1144 (1260), μ = 2.046 (2.951) cm-1, R = 0.0687 (0.0749) and wR = 0.1306 (0.1507) for observed reflections with I > 2σ(I). X-ray structures of 1 and 2 definitively prove that only one sulfur atom is inserted into the Ln-C(nBu) bond, forming a thiolate ligand.

  6. Electrochemical and spectroscopic investigation of Ln3+ (Ln = Sm, Eu, and Yb) solvation in bis(trifluoromethylsulfonyl)imide-based ionic liquids and coordination by N,N,N',N'-tetraoctyl-3-oxa-pentane diamide (TODGA) and chloride.

    Science.gov (United States)

    Pan, Yunfeng; Hussey, Charles L

    2013-03-18

    The electrochemistry and electronic absorption spectroscopy of samarium, europium, and ytterbium were investigated in the 1-(1-butyl)trimethylammonium bis(trifluoromethylsulfonyl)imide (BuMe3NTf2N) and 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BuMePyroTf2N) ionic liquids and in these solvents containing the neutral tridentate ligand N,N,N',N'-tetraoctyl-3-oxo-pentane diamide (TODGA) and the anionic hard ligand chloride. Lanthanide ions were introduced into the ionic liquids by controlled potential oxidation of the respective metals to yield solutions containing Eu(2+), Sm(3+), and Yb(3+), and it was possible to cycle between Eu(2+) and Eu(3+) as well as Yb(3+) and Yb(2+) using controlled potential electrolysis. Electronic absorption spectroscopy suggested that the Ln(3+) species are weakly solvated by Tf2N(-) anions as [Ln(Tf2N)x]((x-3)-) in the neat ILs. The quasireversible Ln(3+/2+) couples of all three elements were readily accessible in these ILs, but Sm(2+) was only stable on the voltammetric time scale. Addition of TODGA to [Ln(Tf2N)x]((x-3)-) solutions produces 3:1 complexes with Eu(3+) and Sm(3+) but only a 2:1 complex with the smaller Yb(3+) ion. Depending on the temperature, addition of Cl(-) to solutions of [Ln(Tf2N)x]((x-3)-) induces precipitation of LnCl3(s) when the mole ratio mCl(-)/mLn(3+) ≈ 3. However, when mCl(-)/mLn(3+) > 3, these precipitates redissolve to form the octahedral chloride complexes, [LnCl6](3-).

  7. 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.

  8. Crystal Structure and Luminescence of the Orthoborate Ln1-xBO3:Eux(Ln=Y,Gd)%稀土正硼酸盐Ln{1-xBO3:Eux(Ln=Y,Gd)的结构与发光特性

    Institute of Scientific and Technical Information of China (English)

    张巍巍; 谢平波; 张慰萍; 尹民; 荆隆; 吕少哲; 楼立人; 夏上达

    2001-01-01

    LnBO3:Eu(Ln=Y,Gd)orthoborates were prepared by solid state reaction and sol-gel technique. Nephelauxetic effect was observed in the 7F0?5D0 transition of Eu3+ in a pseudo-vaterite type YBO3 when the excitation spectra were carried out at different temperatures. According to the luminescence of YBO3:Eu at low temperatures and the effect of different temperatures on the luminescence, the site symmetries of Ln3+ in YBO3 were revised to be a D3 and a similar C3. Different luminescent intensities and quenching concentrations were found for the sol-gel samples and corresponding solid-state-synthesized ones. The effect of defects or dislocations was taken into account to explain these phenomena. The luminescence of annealed samples and the Raman spectra of them suggested the presence of Eu3+ clusters in the sol-gel crystalline YBO3:Eu.%用溶胶-凝胶法和高温固相反应分别制备了纳米量级和常规尺度的稀土正硼酸盐荧光粉LnBO3:Eu(Ln=Y,Gd),测量了它们的激发光谱并首次观察到了YBO3:Eu中Eu3+的7F05D0跃迁的Nephelauxetic效应. 根据低温下的激发光谱,发射光谱以及变温条件对发光光谱的影响, YBO3中Ln3+所占据的两种格位的对称性被修正为C3?和D3. 在不同方法制备的样品中观察到了不同的发光强度和猝灭浓度. 缺陷?的影响是产生这种不同的原因. 退火样品的发光和拉曼散射谱的变化反映出掺杂的杂质Eu3+的团聚化是可能的缺陷来源.

  9. Optical characterization and the energy level scheme for NaYP{sub 2}O{sub 7}:Ln{sup 3+} (Ln=Ce, Sm, Eu, Tb, Yb)

    Energy Technology Data Exchange (ETDEWEB)

    Novais, S.M.V., E-mail: suellenvaleriano@yahoo.com.br [Laboratory of Advanced Ceramic Materials, Physics Department, Federal University of Sergipe, 49.100-000, São Cristóvão, SE (Brazil); Dobrowolska, A.; Bos, A.J.J.; Dorenbos, P. [Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Macedo, Z.S. [Laboratory of Advanced Ceramic Materials, Physics Department, Federal University of Sergipe, 49.100-000, São Cristóvão, SE (Brazil)

    2014-04-15

    Vacuum ultra-violet spectroscopy at low temperature was performed with undoped and Ln{sup 3+}-doped NaYP{sub 2}O{sub 7} (Ln=Ce, Sm, Eu, Tb and Yb). The emission observed from the NaYP{sub 2}O{sub 7} host was attributed to self-trapped exciton (STE) recombination. Dopant ions were well incorporated and responsible for characteristic luminescent emission in the doped samples. From excitation curves, 4f–5d transitions were identified for Ce{sup 3+}, Sm{sup 3+} and Tb{sup 3+} and charge transfer processes were noticed for Eu{sup 3+}, Sm{sup 3+} and Yb{sup 3+}. The experimental data obtained was used to determine the positions of the energy levels of divalent and trivalent lanthanides relative to the valence and conduction band of this compound. The experimentally derived levels are in good agreement with model predictions. The results are valuable to provide a better understanding on the performance of NaYP{sub 2}O{sub 7} and related diphosphates as luminescent materials. -- Highlights: • NaYP{sub 2}O{sub 7} polycrystalline samples were produced via the sol–gel method. • VUV excitation and emission spectra were successfully studied. • Luminescent properties were discussed. • The experimentally derived energy levels are in good agreement with model predictions.

  10. Preparation and characterization of new mixed sandwiched layered compounds Ln/sub 32/Nb/sub 28/S/sub 88/ (Ln = La, Ce)

    Energy Technology Data Exchange (ETDEWEB)

    Meerschaut, A.; Rabu, P.; Rouxel, J.

    1989-01-01

    New ternary Ln/sub 32/Nb/sub 28/S/sub 88/ (Ln = La, Ce) compounds have been obtained. They crystallize in the orthorhombic space group (Ccca) with a = 23.031(9) /angstrom/, b = 23.216(6) /angstrom/, c = 5.806(2) /angstrom/, and a = 22.877(9) /angstrom/, b = 23.127(13) /angstrom/, c = 5.775(2) /angstrom/ for La/sub 32/Nb/sub 28/S/sub 88/ and Ce/sub 32/Nb/sub 28/S/sub 88/, respectively. The structure of La/sub 32/Nb/sub 28/S/sub 88/ (Z = 1) has been refined until R = 0.155 for 639 reflections with I />=/ 4sigmaI and 56 variables. The structure may be described as a mixed sandwiched layered type where /absolute value/NbS/sub 2/ and /absolute value/LaS slabs alternate. These new compounds may be classified as misfit layer compounds.

  11. Combinative energy,oxygen deficiency and superconductivity in LnBa2Cu3O7-x (Ln=Nd,Er,Sm)

    Institute of Scientific and Technical Information of China (English)

    王淑霞; 刘文利; 韩圣浩; 张酣

    2003-01-01

    The correlation among the combinative energy, superconductivity, oxygen content, the position of holes in different planes, and the position of holes in the Cu(2)-O plane in LnBa2Cu3O7-x (Ln= Nd, Er, and Sm) has been investigated on the basis of a block model. The results indicate that the combinative energy decreases with increasing Tc in all of these compounds. And also, the combinative energies are obviously different with holes at different positions in the Cu(2)-O plane when the oxygen deficiency is low. However, this difference becomes less with increasing the oxygen deficiency.The effect of the holes in different positions on the combinative energy supplies some clue to the understanding of an unresolved problem, i.e. whether the distribution of carriers in the CuO2 plane is uniform or inhomogeneous. The results not only show that the structural characters, the combinative energy between two structural blocks and the superconductivity are closely interrelated in this class of compounds, but also reveal some differences among these systems. The relationship between the combinative energy and the Tc value in NdBa2Cu3O7-x shows some features different from the systems containing Er or Sm.

  12. Synthesis and structure of Ln sub 2 Ta sub 3 Se sub 2 O sub 8 (Ln = La, Ce, Pr, Nd)

    Energy Technology Data Exchange (ETDEWEB)

    Brennan, T.; Aleandri, L.; Ibers, J. (Northwestern Univ., Evanston, IL (USA))

    1991-04-01

    A series of compounds Ln{sub 2}Ta{sub 3}Se{sub 2}O{sub 8}(Ln = La, Ce, Pr, Nd) has been prepared and characterized. Pr{sub 2}Ta{sub 3}Se{sub 2}O{sub 8} is orthorhombic, space group D{sub 2h}{sup 12}{minus}Pnnm, with unit cell constants a = 9.882(3), b = 11.774(3), c = 7.601(2) {angstrom}, T = 111 K, Z = 4. The structure has been solved and refined from single crystal x-ray diffraction data. The structure, including the oxygen content and positions, has been confirmed from neutron diffraction powder data. The asymmetric unit contains two independent Pr atoms, two independent Ta atoms, two independent Se atoms, five independent O atoms. The Pr atoms are in tricapped-trigonal prismatic sites enclosed by seven O and two Se atoms. One Ta atom is in a distorted octahedral site surrounded by six O atoms, and the other Ta atom is also in a distorted octahedral environment but has two trans O and four Se atoms in its coordination sphere.

  13. Magnetocaloric effect of a series of remarkably isostructural intermetallic [Ni(II)3Ln(III)] cubane aggregates.

    Science.gov (United States)

    Wang, Pei; Shannigrahi, Santiranjan; Yakovlev, Nikolai L; Hor, T S Andy

    2014-01-07

    A new series of remarkably isostructural 3d-4f compounds, [Ni3Ln(hmp)4(OAc)5]·H2O·CH2Cl2 (Ln = Gd (1), Tb (2), Dy (3), Ho (4), Y (5)) were synthesized based on a simple one-pot self-assembly method. Magnetic measurements demonstrated the ferromagnetic property of the [Ni3Ln] cores and the heterometallic influence on the magnetocaloric properties. This study suggested that robust and discrete intermetallic cubanes can be an alternative to other magnetically active materials such as high-nuclearity aggregates or clusters whose structures are not generally controlled by common synthetic methodological designs.

  14. Octanuclear [Ni(II)₄Ln(III)₄] complexes. Synthesis, crystal structures and magnetocaloric properties.

    Science.gov (United States)

    Pasatoiu, Traian D; Ghirri, Alberto; Madalan, Augustin M; Affronte, Marco; Andruh, Marius

    2014-06-28

    Two original heterooctanuclear [Ni(II)4Ln(III)4] complexes (Ln(III) = Sm(III), Gd(III)) have been obtained starting from the [Ni(II)(valpn)(H2O)2] mononuclear precursor [H2valpn = 1,3-propanediylbis(2-iminomethylene-6-methoxy-phenol)] and the corresponding lanthanide nitrates, in the presence of azide anions, through slow capture of atmospheric CO2. Three weak and competitive exchange interactions, J(GdGd), J(GdNi), J(NiNi), make the ground state of this magnetic system degenerate at cryogenic temperature and zero field. This, along with the high spin of Gd(III), lead to a significant magnetocaloric effect spread in the temperature range 1 to 20 K (ΔSm[0-7 T, 3.5 K] = 19 J kg(-1) K(-1)).

  15. Martensitic transformation during fatigue testing of an AISI 301LN steel

    OpenAIRE

    Mateo García, Antonio Manuel; Fargas Ribas, Gemma

    2012-01-01

    The plastic deformation accumulated during fatigue testing can induce the transformation of austenite to martensite in metastable austenitic stainless steels. To analyze this issue, a metastable austenitic stainless steel grade AISI 301 LN was studied in two different conditions, i.e. annealed and cold rolled. In the first case, the steel was fully austenitic, whereas cold rolled material had almost 30% of martensite. High cycle fatigue tests at a stress ratio of 0.8 were carried out on flat ...

  16. Analytic Amplitudes for Hadronic Forward Scattering and the Heisenberg ln**2 Behaviour of Total Cross Sections

    CERN Document Server

    Nicolescu, B

    2004-01-01

    The ln**2 behaviour of total cross sections, first obtained by Heisenberg 50 years ago, receives now increased interest both on phenomenological and theoretical levels. We present a modification of the Heisenberg's model in connection with the presence of glueballs and we show that it leads to a realistic description of all existing hadron total cross-section data, in agreement with the COMPETE analysis.

  17. Sulfur Earth

    Science.gov (United States)

    de Jong, B. H.

    2007-12-01

    Variations in surface tension affect the buoyancy of objects floating in a liquid. Thus an object floating in water will sink deeper in the presence of dishwater fluid. This is a very minor but measurable effect. It causes for instance ducks to drown in aqueous solutions with added surfactant. The surface tension of liquid iron is very strongly affected by the presence of sulfur which acts as a surfactant in this system varying between 1.9 and 0.4 N/m at 10 mass percent Sulfur (Lee & Morita (2002), This last value is inferred to be the maximum value for Sulfur inferred to be present in the liquid outer core. Venting of Sulfur from the liquid core manifests itself on the Earth surface by the 105 to 106 ton of sulfur vented into the atmosphere annually (Wedepohl, 1984). Inspection of surface Sulfur emission indicates that venting is non-homogeneously distributed over the Earth's surface. The implication of such large variation in surface tension in the liquid outer core are that at locally low Sulfur concentration, the liquid outer core does not wet the predominantly MgSiO3 matrix with which it is in contact. However at a local high in Sulfur, the liquid outer core wets this matrix which in the fluid state has a surface tension of 0.4 N/m (Bansal & Doremus, 1986), couples with it, and causes it to sink. This differential and diapiric movement is transmitted through the essentially brittle mantle (1024 Pa.s, Lambeck & Johnson, 1998; the maximum value for ice being about 1030 Pa.s at 0 K, in all likely hood representing an upper bound of viscosity for all materials) and manifests itself on the surface by the roughly 20 km differentiation, about 0.1 % of the total mantle thickness, between topographical heights and lows with concomitant lateral movement in the crust and upper mantle resulting in thin skin tectonics. The brittle nature of the medium though which this movement is transmitted suggests that the extremes in topography of the D" layer are similar in range to

  18. Study of LnBaCo{sub 2}O{sub 6-d}elta (Ln = Pr, Nd, Sm and Gd) double perovskites as new cathode material for IT-SOFC

    Energy Technology Data Exchange (ETDEWEB)

    Chavez, E; Mueller, M; Mogni, L; Caneiro, A, E-mail: mogni@cab.cnea.gov.a [Centro Atomico Bariloche-CNEA, Instituto Balseiro. Av. Bustillo 9500, S. C. de Bariloche 8400 (Argentina)

    2009-05-01

    Oxides with double perovskites structures of general composition LnBaCo{sub 2}O{sub 6-d}elta (Ln = Pr, Nd, Sm and Gd) were synthesized by solid state reaction with the purpose to evaluate new materials to be used as cathodes in intermediate temperature solid oxide fuel cell (IT-SOFC). A preliminary study about electrochemical properties was performed by impedance spectroscopy between 500 and 800 deg. C under atmosphere of pure O{sub 2}. Symmetrical cells were obtained by spray deposition of LnBaCo{sub 2}O{sub 6-d}elta (Ln = Pr, Nd, Sm and Gd) at both sides of a dense ceramic electrolyte. The impedance spectroscopy measurements as a function of temperatures show a hysteresis loop which could be associated to a tetragonal/orthorhombic phase transition. The existence of this transition was corroborated by high temperature X-Ray diffraction and Differential Scanning Calorimetry measurements.

  19. Photoluminescence and electron-vibrational interaction in 4f{sup n-1}5d states of Ce{sup 3+} or Pr{sup 3+} ions doped LnBO{sub 3} (Ln=Lu, Y, La) orthoborates materials

    Energy Technology Data Exchange (ETDEWEB)

    Guerbous, L., E-mail: guerbous@yahoo.fr [Laser Department, Nuclear Techniques Division, Algiers Nuclear Research Center, 02, bd Frantz Fanon, BP 399, Algiers 16000 (Algeria); Seraiche, M. [Laser Department, Nuclear Techniques Division, Algiers Nuclear Research Center, 02, bd Frantz Fanon, BP 399, Algiers 16000 (Algeria); Department of Materials and Components, Faculty of Physics, USTHB (Algeria); Krachni, O. [Departement de Physique, Faculte des Sciences, Universite Ferhat Abbas Setif 19000 (Algeria)

    2013-02-15

    Calcite, vaterite and aragonite type rare earth LnBO{sub 3} (Ln=Lu, Y, La) orthoborate powders, doped with 1% cerium or praseodymium, were prepared by the classical solid state reaction method. The structure and the morphology of these powder materials were checked by X-ray Diffraction, Fourier Transform Infra Red Spectroscopy (FTIR) and Scanning Electron Microscopy. Room temperature excitation and emission spectra of four compounds: LuBO{sub 3} with calcite and vaterite structure, YBO{sub 3} (vaterite type structure) and LaBO{sub 3} with aragonite, doped with 1% cerium or praseodymium ions, have been measured and investigated. The effect of Ce{sup 3+} and Pr{sup 3+} crystalline environment in these compounds on the position of their 5d (4f5d) levels has been discussed. This work is also devoted to the problem of the electron-vibrational interaction (EVI) in 4f-5d optical transitions in orthoborate materials. The emission and excitation 4f-5d transitions resulted in broad vibronic bands whose shape functions were described and found. The main EVI parameters, such as the Huang-Rhys factor, effective phonon energy, and zero-phonon line position, were estimated. These values are checked by modeling the Ce{sup 3+} 5d-4f and Pr{sup 3+} 4f5d-4f{sup 2} emission lines shapes, in which good agreement with experimental spectra confirms validity of the performed analysis. - Highlights: Black-Right-Pointing-Pointer Ce{sup 3+} and Pr{sup 3+}-doped calcite, vaterite and aragonite LnBO{sub 3} (Ln=Lu, Y, La) orthoborates were successfully prepared by the solid state reaction method. Black-Right-Pointing-Pointer The effect of Ce{sup 3+} and Pr{sup 3+} crystalline environment in orthoborates on the position of their 5d levels has been discussed. Black-Right-Pointing-Pointer The main electron-vibrational interaction parameters (EVI), such as the Huang-Rhys factor, effective phonon energy, and zero-phonon line position, were estimated and discussed.

  20. Equipping an FPGA-Based Mars Rover With an LN-200 IMU

    Science.gov (United States)

    Zola, Nicholas J.

    2005-01-01

    The Mars Exploration Rovers (MER) currently navigating the surface of Mars are outfitted with an advanced stereovision correlation algorithm which allows them to "see" three-dimensionally and autonomously avoid obstac'les in their path. A bottleneck of this system is that it is computationally intense and requires 3 minutes of processing for every correlated image and path choice. Taking advantage of the optimization and reprogrammability of FPGAs, the Mobility Avionics lab has reduced this process to under a second. The lab is demonstrating the advancement with a prototype rover, complete with an LN-200 inertial measurement unit (IMU), which is a flight spare from MER. The LN-200 is a space-grade, six degrees-of-freedom IMU using three fiber-optic gyroscopes and three silicon accelerometers and no moving parts. It has particular power-sequencing needs and communicates with a specialized serial protocol (SDLC over RS-422), requiring specific hardware and software for proper functionality and interfacing with an FPGA. The process of incorporating the LN-200 into the system is described herein.

  1. Low-x contribution to the Bjorken sum rule within double logarithmic $ln^2x$ approximation

    CERN Document Server

    Kotlorz, D; Kotlorz, Dorota; Kotlorz, Andrzej

    2004-01-01

    The small-$x$ contributions to the Bjorken sum rule within double logarithmic $ln^2x$ approximation for different input parametrisations $g_1^{NS}(x,Q_0^2)$ are presented. Analytical solutions of the evolution equations for full and truncated moments of the unintegrated structure function $f^{NS}(x,Q^2)$ are used. Theoretical predictions for $\\int_{0}^{0.003} g_1^{NS}(x,Q^2=10) dx$ are compared with the SMC small-$x$ data. Rough estimation of the slope $\\lambda$, controlling the small-$x$ behaviour of $g_1^{NS}\\sim x^{-\\lambda}$ from the SMC data is performed. Double logarithmic terms $\\sim (\\alpha_s ln^2x)^n$ become leading when $x\\to 0$ and imply the singular behaviour of $g_1^{NS}\\sim x^{-0.4}$. This seems to be confirmed by recent experimental SMC and HERMES data. Advantages of the unified $ln^2x$+LO DGLAP approach and the crucial role of the running coupling $\\alpha_s=\\alpha_s(Q^2/z)$ at low-$x$ are also discussed.

  2. Why Was Kelvin's Estimate of the Earth's Age Wrong?

    Science.gov (United States)

    Lovatt, Ian; Syed, M. Qasim

    2014-05-01

    This is a companion to our previous paper in which we give a published example, based primarily on Perry's work, of a graph of ln y versus t when y is an exponential function of t. This work led us to the idea that Lord Kelvin's (William Thomson's) estimate of the Earth's age was wrong not because he did not account for radioactivity, as is commonly believed,4 but because he used the wrong model for Earth's heat loss. We feel this idea is worth spreading. To this end (following England et al.), we examine two questions, the first about the radioactivity part and the second about Perry's alternate model for Earth's heat loss.

  3. Synthesis, Characterization of α-Oxopentanedioic Acid-Isonicotinoyl Hydrazone Rare Earth-Complexes and Relaxivity of Gd-complex

    Institute of Scientific and Technical Information of China (English)

    杨正银; 杨汝栋

    2004-01-01

    α-Oxopentanedioic acid isonicotinoyl hydrazone (H2L) and its five rare earth complexes were synthesized with a view to further investigating MRI activities of the polycarboxylic Schiff base complexes. The complexes were characterized on the basis of elemental analyses, IR, UV, 1H NMR spectra and thermal analyses. The general formula of the complexes is [Ln(HL)(H2O)2]Cl2·H2O (where Ln(Ⅲ)=La, Pr, Nd, Eu and Gd). In addition, the relaxivity (R1) of the Gd-complex was determined by INVREC Au program.

  4. Synthesis and Structures of Two Lanthanide Complexes Containing a Mixed Ligand System: [Ln(Phen){sub 2}(L){sub 3}(HL)]·H{sub 2}O [Ln = La, Ce; Phen = Phenanthroline; HL = Salicylic Acid

    Energy Technology Data Exchange (ETDEWEB)

    Iravani, Effat [UNiv. of Applied Science and Technology, Tehran (Iran, Islamic Republic of); Nami, Navabeh; Nabizadeh, Fatemeh; Bayani, Elham [Islamic Azad Univ., Mazandaran (Iran, Islamic Republic of); Neumueller, Bernhard [Philipps-Universitat Marburg, Marburg (Germany)

    2013-11-15

    The reaction of LnCl{sub 3}·7H{sub 2}O [Ln = La (1), Ce (2)] with salicylic acid (HL) and 1,10-phenanthroline (Phen) at 20 .deg. C in H{sub 2}O/ethanol gave after work-up and recrystallization two novel lanthanide complexes with general formula [Ln(Phen){sub 2}(L){sub 3}(HL)]·H{sub 2}O. Compounds 1 and 2 were characterized by IR and UV-Vis spectroscopy, TGA, CHN as well as by X-ray analysis. According to these results, compounds 1 and 2 are isostructural and contain Ln{sup 3+} ions with coordination number nine. Complexes 1 and 2 consist of two Phen, one neutral HL and three L anions (two L anions act as monodentate ligands and the third one is chelating to Ln{sup 3+}). Thermal decomposition led to primary loss of the Phen molecules. Then HL molecules and finally L moieties left the material to give Ln{sub 2}O{sub 3}.

  5. Synthesis and photoluminescence studies of Ba(Gd,Ln)B9O16:Eu3+(Ln=La,Y) phosphors for n-UV LED lighting and display devices

    Institute of Scientific and Technical Information of China (English)

    V.V. Rangari; S.J. Dhoble

    2015-01-01

    BaGdB9O16:Eu3+ and Ba(Gd,Ln)B9O16:Eu3+(Ln=La, Y) phosphors were synthesized by solid state diffusion method. The X-ray diffraction, scanning electron microscopy (SEM) and photoluminescence properties were investigated. The as-synthesized BaGdB9O16:Eu3+and Ba(Gd,Ln)B9O16:Eu3+(Ln=La, Y) phosphors showed strong red emission under ultraviolet light excitation. By partially substituting Gd3+by La3+and Y3+ions in the host BaGdB9O16:Eu3+materials, the maximum emission intensity was observed for the optimum composition of BaGd0.91La0.8B9O16Eu0.01 phosphor. The experimental results indicated that the Eu doped BaGdB9O16 and Ba(Gd,Ln)B9O16 (Ln=La, Y) phosphors were promising red phosphors, which might find po-tential applications in near-UV excited LED lighting as well as display devices. Comparison of as-synthesized phosphors with standard phosphor used in CFL (compact fluorescent lamp) was also done. Energy transfer mechanism of Gd3+to Eu3+was also discussed in this paper.

  6. Structural and IR-spectroscopic characterization of some new Sr{sub 2}LnSbO{sub 6} perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Lavat, Araceli E. [Departamento de Ingenieria Quimica, Facultad de Ingenieria, Universidad Nacional del Centro de la Provincia de Buenos Aires, 7400 Olavarria (Argentina); Baran, Enrique J. [Centro de Quimica Inorganica (CEQUINOR/CONICET, UNLP), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C. Correo 962, 1900 La Plata (Argentina)], E-mail: baran@quimica.unlp.edu.ar

    2008-07-28

    A series of ternary perovskite-type oxides of composition Sr{sub 2}LnSbO{sub 6} (with Ln = La, Nd, Sm, Gd, Dy, Er, Yb and Y), have been prepared and their unit cell parameters determined by X-ray powder diffractometry. The infrared spectra of these materials were also recorded and briefly discussed on the basis of their structural peculiarities and by comparison with those of related oxides.

  7. Energy Equality and Uniqueness of Weak Solutions to MHD Equations in L∞(O,T;Ln(Ω))

    Institute of Scientific and Technical Information of China (English)

    Yan YONG; Quan Sen JIU

    2009-01-01

    In this paper, we study the energy equality and the uniqueness of weak solutions to the MHD equations in the critical space L∞(O,T; Ln(Ω)). We prove that if the velocity u belongs to the critical space L∞(O,T; Ln(Ω)), the energy equality holds. On the basis of the energy equality, we further prove that the weak solution to the MHD equations is unique.

  8. Electrophilic Ln(III) cations protected by C-F → Ln interactions and their coordination chemistry with weak σ- and π-donors.

    Science.gov (United States)

    Yin, Haolin; Lewis, Andrew J; Carroll, Patrick; Schelter, Eric J

    2013-07-15

    A homoleptic cerium(III) amide complex, Ce(NPh(F)2)3 (1-Ce) (Ph(F) = pentafluorophenyl), in an unusual pseudo-trigonal planar geometry featuring six C-F → Ce interactions was prepared. The C-F → Ln interactions in solution were evident by comparison of the (19)F NMR shifts for the paramagnetic 1-Ce with those of the 4f(0) lanthanum(III) analogue. Coordination of weak σ- and π-donors, including ethers and neutral arene molecules, was achieved by the reversible displacement of the weak C-F → Ce interactions. Computational studies on Ce(NPh(F)2)3 and Ce(NPh(F)2)3(η(6)-C6H3Me3) provide information on the F → Ce interactions and Ce-η(6)-arene bonding.

  9. Existing State and Partitioning of Rare Earth on Weathered Ores

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The existing state and partitioning of rare earth (RE) on weathered ores in Longnan County (LN), Xingfeng County(XF) and Ninghua County(NH) were characterized systematically by standard geological analytical methods. It is found that RE in the weathered rare earth ores exist as four phases: (a) water soluble, (b) ion-exchangeable, (c) colloidal sediment (oxides), (d) minerals, in which mainly as ion exchangeable phase, accounting for nearly 80% of total RE,with about 20% in the form of colloid sediment phase and mineral phase, but very little as aqueous soluble phase. These rare earth partitioning were mainly chosen mid-heavy RE elements, occupying above 60%, but not equal in the four phases. The mid-heavy RE elements were primarily enriched in the ion exchangeable phase up to 40%, while the containment of cerium dioxide is below 2%. The cerium deficiency occurs in the ion exchangeable phase in weathered ore. It results from that the Ce3+ is oxidized into Ce4+ and changes into CeO2. For LN ore, the containment of Y is high in weathered ore because Y-minerals are abundant in original rock.

  10. Synthesis and crystal structure determination of some polymetallic oxalates of U{sup IV}, Na, Ln{sup III} (Ln = Ce and Nd)

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-07-01

    In the course of investigations of oxalic coprecipitation of uranium(IV) and cerium (III) an oxalate containing also sodium ions was isolated. Its structure was determined by single crystal X-ray diffraction and led to the formula (U{sub 1}Ce{sub 1})Na{sub 3}(C{sub 2}O{sub 4}){sub 5} 10.4H{sub 2}O. Astonishingly, the two heavy metallic ions occupy the same crystallographic site, the alkaline ion assuring the charge neutrality. This behaviour has also been evidenced on two oxalates of uranium(IV) and neodymium(III) exhibiting various ratio U(IV)/Nd(III). Though (U{sub 1.44}Nd{sub 0.56})Na{sub 2.4}(C{sub 2}O{sub 4}){sub 5} 10H{sub 2}O and (U{sub 1}Ce{sub 1})Na{sub 3}(C{sub 2}O{sub 4}){sub 5} 10.4H{sub 2}O present different ratio U(IV)/Ln(III), their crystallographic structures are similar. In these three-dimensional structural arrangements, uranium(IV) and lanthanide(III) are surrounded by five bidentate oxalate units and water molecules lie in the middle of (U,Ln){sub 3}(C{sub 2}O{sub 4}){sub 6} honeycomb hexagonal six-membered rings. Although the synthesis conditions are close, (U{sub 1}Nd{sub 1})Na(C{sub 2}O{sub 4}){sub 4} 8H{sub 2}O is built from an unlike coordination polyhedra which is constituted of four bidentate oxalate ligands and one water molecule.

  11. 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.

  12. Synthesis and photocatalytic property of layered perovskite tantalates, RbLnTa{sub 2}O{sub 7} (Ln = La, Pr, Nd, and Sm)

    Energy Technology Data Exchange (ETDEWEB)

    Machida, Masato; Yabunaka, Junichi; Kijima, Tsuyoshi

    2000-03-01

    The first example of an active layered tantalate photocatalyst containing partly filled lanthanide 4f shell is reported. A single phase of layered perovskite tantalates, RbLnTa{sub 2}O{sub 7}, could be obtained with Ln = La, Pr, Nd, and Sm; the ionic radii of these trivalent cations are required to be larger than 0.126 nm for constructing a perovskite slab. Under UV irradiation from a high-pressure Hg lamp, these layered tantalates demonstrated the photocatalytic activity for water splitting into stoichiometric H{sub 2}/O{sub 2} mixtures even without loading metal catalysts. The rates of H{sub 2} and O{sub 2} evolutions were found to be strongly dependent on the lanthanoids, increasing in the sequence of La {approx} Pr << Sm < Nd. The maximum rate of H{sub 2} evolution observed over RbNdTa{sub 2}O{sub 7} reached 47.0 {micro}mol/h. The absorption spectrum of RbNdTa{sub 2}O{sub 7} consists of the internal 4f transitions in the visible region and a broad band overlapping the band-gap transition in the UV region. The latter band indicates that a possible excitation process including the partly filled 4f shell plays a key role in photocatalytic reactions. Loading 0.5 wt % Ni onto RbNdTa{sub 2}O{sub 7} by simple impregnation significantly improved H{sub 2} evolution (117.2 {micro}mol/h).

  13. Effect of Lactobacillus buchneri LN4637 and Lactobacillus buchneri LN40177 on the aerobic stability, fermentation products, and microbial populations of corn silage under farm conditions.

    Science.gov (United States)

    Tabacco, E; Piano, S; Revello-Chion, A; Borreani, G

    2011-11-01

    This study determined the efficacy of the use of 2 commercial inoculants containing Lactobacillus buchneri alone or in combination with homofermentative lactic acid bacteria in improving aerobic stability of corn silage stored in commercial farm silos in northern Italy. In the first survey, samples were collected from 10 farms that did not inoculate their silages and from 10 farms that applied a Pioneer 11A44 inoculant (L. buchneri strain LN4637; Pioneer Hi-Bred International, Des Moines, IA). In the second survey, corn silage samples were collected from 11 farms that did not inoculate their silages and from 11 farms that applied a Pioneer 11CFT inoculant (L. buchneri strain LN40177; Pioneer Hi-Bred International). Inoculants were applied directly through self-propelled forage harvesters, at the recommended rate of 1 g/t of fresh forage, to achieve a final application rate of 1.0 × 10(5) cfu/g of L. buchneri. One corn bunker silo, which had been open for at least 10 d, was examined in detail on each farm. The silages inoculated with L. buchneri had lower concentrations of lactic acid, a lower lactic-to-acetic acid ratio, a lower yeast count, and higher aerobic stability compared with the untreated silages. Unexpectedly, concentrations of acetic acid and 1,2-propanediol, 2 hallmarks of L. buchneri activity, did not differ between treatments and were only numerically higher in the inoculated silages compared with untreated ones, in both surveys. Aerobic stability, on average, was 107 and 121 h in the inoculated silages and 64 and 74 h in the untreated silages, for surveys 1 and 2, respectively, and decreased exponentially as the yeast count in the silage at the time of sampling increased, regardless of treatment. Inoculation with L. buchneri proved to be effective in reducing the yeast count to corn silages in farm bunker silos. Copyright © 2011 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  14. 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)

  15. The effect of recent Venus transit on Earths atmosphere

    OpenAIRE

    H. P. Sardar; Mandal, S. K.; Mandal, P. K.; Guha, A.; Sarkar, S. K.; Sarkar, B. K.; Adhikari, S. K.; De, B. K.; S S; Ray, M.

    2006-01-01

    Some experiments on June 8, 2004, the day of transit of Venus across the Sun, were undertaken at Kolkata (latitude: 22°34lN) to observe the effect, if any, of transit of Venus on FWF, ELF and VLF amplitudes. The result shows a good correlation between their temporal variations during the transit. The observation was unbelievable as the Venus subtends only 1/32th of the cone subtended by Sun on Earth. This anomaly may be explained on the assumption that the height of Venusian atmosphere with h...

  16. Why Was Kelvin's Estimate of the Earth's Age Wrong?

    Science.gov (United States)

    Lovatt, Ian; Syed, M. Qasim

    2014-01-01

    This is a companion to our previous paper in which we give a published example, based primarily on Perry's work, of a graph of ln "y" versus "t" when "y" is an exponential function of "t". This work led us to the idea that Lord Kelvin's (William Thomson's) estimate of the Earth's age was…

  17. Chemical bond properties and charge transfer bands of O(2-)-Eu(3+), O(2-)-Mo(6+) and O(2-)-W(6+) in Eu(3+)-doped garnet hosts Ln3M5O12 and ABO4 molybdate and tungstate phosphors.

    Science.gov (United States)

    Liu, Xiaoguang; Li, Ling; Noh, Hyeon Mi; Moon, Byung Kee; Choi, Byung Chun; Jeong, Jung Hyun

    2014-06-21

    Charge transfer (CT) energy from the ligand to the central ions is an important factor in luminescence properties for rare earth doped inorganic phosphors. The dielectric theory of complex crystals was used to calculate chemical bond properties. Combining the photoluminescence and the dielectric theory of complex crystals, the CT bands of O(2-)-Eu(3+), O(2-)-Mo(6+) and O(2-)-W(6+) for Eu(3+)-doped inorganic phosphors have been investigated experimentally and theoretically. Taking Eu(3+)-doped Ln3M5O12 (Ln = Y, Lu and M = Al, Ga), Gd3Ga5O12, MMoO4 (M = Ca, Sr, Ba) and MWO4 (M = Ca, Sr, Ba) as typical phosphors, we investigated the effects of the cation size on the CT bands and chemical bond properties including the bond length (d), the covalency (fc), the bond polarizability (αb) and the environmental factor (he) of O(2-)-Eu(3+), O(2-)-Mo(6+) and O(2-)-W(6+), respectively. For systematic isostructural Ln3M5O12 (Ln = Y, Lu and M = Al, Ga) phosphors, with the increasing M ion radius, the bond length of Ln-O decreases, but fc and αb increase, which is the main reason that the environmental factor increased. For the isostructural MMoO4:Eu, with the increasing M ion radius, the Mo-O bond length increases, but fc and αb decrease, and thus he decreases. However, in the compound system MWO4:Eu (M = Ca, Ba) with the increasing M ion radius, the O-W bond length increases, but fc and αb increase, and thus he increases and the O-W CT energy decreases. Their O(2-)-Eu(3+), O(2-)-Mo(6+) and O(2-)-W(6+) CT bands as well as their full width at half maximum (FWHM) were directly influenced by he. And with the increasing he, CT bands of O-Eu or O-Mo or O-W decrease and their FWHM increases. These results indicate a promising approach for changing the material properties, searching for new Eu(3+) doped molybdate, tungstate or other oxide phosphors and analyzing the experimental result.

  18. Simultaneous observation of low temperature 4f-4f and 3d-3d emission spectra in a series of Cr(III)(ox)Ln(III) assembly

    CERN Document Server

    Subhan, M A; Suzuki, T; Choi, J H; Kaizaki, S

    2003-01-01

    We report here the low temperature emission spectra in the heterometal dinuclear 3d-4f assembled molecular system [(acac) sub 2 Cr sup I sup I sup I (mu-ox)Ln sup I sup I sup I (HBpz sub 3) sub 2] (Cr(ox)Ln:acac sup - =acetylacetonate, ox sup 2 sup - =oxalate, HBpz sub 3 sup - =hydrotris(pyrazol-1-yl)borate; Ln=La, Nd, Ho, Er , Tm and Yb) in comparison with those of Na[Cr(acac) sub 2 (ox)] and [(HBpz sub 3) sub 2 Ln(mu-ox)Ln(HBpz sub 3) sub 2](Ln=Nd and Er). From 10 to 150 K the Cr(ox)Ln complexes show a broad emission band around 800 nm from the sup 2 E state of Cr(III) moiety. At room temperature no sup 2 E- sup 4 A sub 2 emission was observed in the Cr(ox)Ln except for the La and Lu complexes. On warming from 10 to 300 K rapid quenching of the sup 2 E- sup 4 A sub 2 emission of Cr(III) is suggested to result from the energy transfer from Cr to Ln in the Cr(ox)Ln. The excitation spectra and the life-time were also measured with monitoring the 4f-4f emission peaks of the Cr(ox)Yb complex.

  19. Agreement between a smart-phone pulse sensor application and ECG for determining lnRMSSD.

    Science.gov (United States)

    Esco, Michael R; Flatt, Andrew A; Nakamura, Fabio Y

    2016-06-27

    The purpose of this study was to determine the agreement between a smartphone pulse finger sensor (SPFS) and electrocardiography (ECG) for determining ultra-short-term heart rate variability (HRV) in three different positions. Thirty college-aged men (n = 15) and women (n = 15) volunteered to participate in this study. Sixty second heart rate measures were simultaneously taken with the SPFS and ECG in supine, seated and standing positions. lnRMSSD was calculated from the SPFS and ECG. The lnRMSSD values were 81.5 ± 11.7 via ECG and 81.6 ± 11.3 via SPFS (p = 0.63, Cohen's d = 0.01) in the supine position, 76.5 ± 8.2 via ECG and 77.5 ± 8.2 via SPFS (p = 0.007, Cohen's d = 0.11) in the seated position, and 66.5 ± 9.2 via ECG and 67.8 ± 9.1 via SPFS (p < 0.001, Cohen's d = 0.15) in the standing positions. The SPFS showed a possibly strong correlation to the ECG in all three positions (r values from 0.98 to 0.99). In addition, the limits of agreement (CE ± 1.98 SD) were -0.13 ± 2.83 for the supine values, -0.94± 3.47 for the seated values, and -1.37 ± 3.56 for the standing values. The results of the study suggest good agreement between the SPFS and ECG for measuring lnRMSSD in supine, seated, and standing positions. Though significant differences were noted between the two methods in the seated and standing positions, the effect sizes were trivial.

  20. Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Oversupply of rare earths led to the significant price drop of rare earth mineral products and separated products in Chinese domestic market. To stabilize the price, prevent waste of resources, further improve regulation capability on domestic rare earth market and rare earth price and maintain sustaining and healthy development of rare earth industry, partial rare earth producers in Baotou and Jiangxi province projected to cease the production for one month.

  1. HTS SQUID application for measuring the magnetic properties of AISI type 316L(N) steel

    Energy Technology Data Exchange (ETDEWEB)

    Park, D.G. E-mail: dgpark@nanum.kaeri.re.kr; Kim, D.W.; Hong, J.H.; Timofeev, V.P.; Kim, C.G

    2000-06-02

    A portable RF HTS SQUID-based susceptometer was used for small-size magnetized sample testing in weak DC (up to 200 A/m) and AC (up to 4 A/m) magnetic fields. The system resolution for the magnetic moment is of the order of 1.6x10{sup -10} A m{sup 2}. The measured DC susceptibility of a tested sample of Gd{sub 88}La{sub 12} agrees well with the value obtained by using a commercial liquid helium susceptometer. The measured volume susceptibility of AISI type 316L(N) steel increases after fatigue due to the microcrack induced by cyclic stress.

  2. Ln{sub 12}-containing 60-tungstogermanates. Synthesis, structure, luminescence, and magnetic studies

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Kai-Yao; Lin, Zhengguo; Roemer, Isabella; Kortz, Ulrich [Jacobs University, Department of Life Sciences and Chemistry, Bremen (Germany); Bassil, Bassem S. [Jacobs University, Department of Life Sciences and Chemistry, Bremen (Germany); Department of Chemistry, Faculty of Sciences, University of Balamand, Tripoli (Lebanon); Vanhaecht, Stef; Parac-Vogt, Tatjana N. [Department of Chemistry, KU Leuven (Belgium); Saenz de Pipaon, Cristina [Institute of Chemical Research of Catalonia (ICIQ), Tarragona (Spain); Galan-Mascaros, Jose Ramon [Institute of Chemical Research of Catalonia (ICIQ), Tarragona (Spain); Catalan Institution for Research and Advanced Studies (ICREA), Barcelona (Spain); Fan, Linyuan; Cao, Jie [Key Laboratory of Cluster Science, Ministry of Education of China, Beijing Key Laboratory of Photoelectronic/Electrophotonic, Conversion Materials, School of Chemistry, Beijing Institute of Technology (China)

    2015-12-07

    A new class of hexameric Ln{sub 12}-containing 60-tungstogermanates, [Na(H{sub 2}O){sub 6} is contained in Eu{sub 12}(OH){sub 12}(H{sub 2}O){sub 18}Ge{sub 2}(GeW{sub 10}O{sub 38}){sub 6}]{sup 39-} (Eu{sub 12}), [Na(H{sub 2}O){sub 6} is contained in Gd{sub 12}(OH){sub 6}(H{sub 2}O){sub 24}Ge(GeW{sub 10}O{sub 38}){sub 6}]{sup 37-} (Gd{sub 12}), and [(H{sub 2}O){sub 6} is contained in Dy{sub 12}(H{sub 2}O){sub 24}(GeW{sub 10}O{sub 38}){sub 6}]{sup 36-} (Dy{sub 12}), comprising six di-Ln-embedded {β(4,11)-GeW_1_0} subunits was prepared by reaction of [α-GeW{sub 9}O{sub 34}]{sup 10-} with Ln{sup III} ions in weakly acidic (pH 5) aqueous medium. Depending on the size of the Ln{sup III} ion, the assemblies feature selective capture of two (for Eu{sub 12}), one (for Gd{sub 12}), or zero (for Dy{sub 12}) extra Ge{sup IV} ions. The selective encapsulation of a cationic sodium hexaaqua complex [Na(H{sub 2}O){sub 6}]{sup +} was observed for Eu{sub 12} and Gd{sub 12}, whereas Dy{sub 12} incorporates a neutral, distorted-octahedral (H{sub 2}O){sub 6} cluster. The three compounds were characterized by single-crystal XRD, ESI-MS, photoluminescence, and magnetic studies. Dy{sub 12} was shown to be a single-molecule magnet. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Primer caso de hemoglobina Köln (codon98 GTG>ATG en Costa Rica

    Directory of Open Access Journals (Sweden)

    Walter Cartín

    2010-03-01

    Full Text Available La exposición a ciertos medicamentos puede provocar anemia hemolítica con presencia de cuerpos de Heinz en sangre periférica. Esta anemia puede presentarse por sobredosis de medicamentos, tanto en individuos sanos como en personas con deficiencias enzimáticas como la glucosa-6-fosfato deshidrogenasa, o en presencia de hemoglobinas inestables. Este reporte muestra un caso de anemia hemolítica con cuerpos de Heinz, debido a la presencia de una hemoglobina inestable, cuyos estudios moleculares y HPLC confirmaron el primer caso descrito de hemoglobina Köln (Val98Met en Costa Rica.

  4. SPECTROSCOPIC PROPERTIES OF THE Ln-Ge COMPLEXES WITH DIETHYLENETRIAMINEPENTAACETIC ACID

    Directory of Open Access Journals (Sweden)

    Sergiy Smola

    2007-06-01

    Full Text Available Four new heteronuclear lanthanide complexes with general formula [Ge(OH(μ-HDTPALnGe(OH (μ-DTPA] (Ln = Sm – Dy were synthesized and subsequently characterized by different physico- chemical methods. The structures of new compounds have been proposed. In considered complexes the 4f-luminescence of three-charged ions of samarium, europium, terbium and dysprosium is realized at UV-excitation. It is noteworthy that it is the first observation of 4f-luminescence in water solutions of heteronuclear f-p-complexes. The comparison of luminescent characteristics of hetero- and homonuclear landthanide complexes is described and discussed as well.

  5. Ultrasound and Microwave Coassisted Synthesis and Luminescent Properties of (Ln = La, Gd; Phosphors

    Directory of Open Access Journals (Sweden)

    Jing Hu

    2013-01-01

    Full Text Available In order to control reaction temperature and reduce processing time, a new method of ultrasound irradiation with microwave heating was used to synthesize (Ln = La, Gd; phosphors at only 80°C in 30 minutes. Their crystal structures and morphologies which have been verified by X-ray diffraction (XRD and scanning electron microscopy (SEM exhibited gradual changes due to the insertion of lanthanide ions (La or Gd in calcium molybdates. Codoping of lanthanum ions ( would enhance the emission intensities that were supported by fluorescent spectrophotometry (FL.

  6. 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).

  7. 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.

  8. Dopant-induced modification of active site structure and surface bonding mode for high-performance nanocatalysts: CO oxidation on capping-free (110)-oriented CeO2:Ln (Ln = La-Lu) nanowires.

    Science.gov (United States)

    Ke, Jun; Xiao, Jia-Wen; Zhu, Wei; Liu, Haichao; Si, Rui; Zhang, Ya-Wen; Yan, Chun-Hua

    2013-10-09

    Active center engineering at atomic level is a grand challenge for catalyst design and optimization in many industrial catalytic processes. Exploring new strategies to delicately tailor the structures of active centers and bonding modes of surface reactive intermediates for nanocatalysts is crucial to high-efficiency nanocatalysis that bridges heterogeneous and homogeneous catalysis. Here we demonstrate a robust approach to tune the CO oxidation activity over CeO2 nanowires (NWs) through the modulation of the local structure and surface state around Ln(Ce)' defect centers by doping other lanthanides (Ln), based on the continuous variation of the ionic radius of lanthanide dopants caused by the lanthanide contraction. Homogeneously doped (110)-oriented CeO2:Ln NWs with no residual capping agents were synthesized by controlling the redox chemistry of Ce(III)/Ce(IV) in a mild hydrothermal process. The CO oxidation reactivity over CeO2:Ln NWs was dependent on the Ln dopants, and the reactivity reached the maximum in turnover rates over Nd-doped samples. On the basis of the results obtained from combined experimentations and density functional theory simulations, the decisive factors of the modulation effect along the lanthanide dopant series were deduced as surface oxygen release capability and the bonding configuration of the surface adsorbed species (i.e., carbonates and bicarbonates) formed during catalytic process, which resulted in the existence of an optimal doping effect from the lanthanide with moderate ionic radius.

  9. A series of noncentrosymmetric antimony sulfides Ln{sub 8}Sb{sub 2}S{sub 15} (Ln = La, Pr, Nd) - syntheses, crystal and electronic structures, and NLO properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Hua-Jun [Laboratory of Applied Research on the Characteristic Resources in the North of Guizhou Province, School of Chemistry and Chemical Engineering, Zunyi Normal College, Guizhou (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou (China); Zhou, Liu-Jiang [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou (China)

    2015-02-15

    A series of noncentrosymmetric sulfides Ln{sub 8}Sb{sub 2}S{sub 15} (Ln = La, Pr, Nd) were prepared from stoichiometric mixtures of the elements at 1223 K in an evacuated silica tube. The compounds Ln{sub 8}Sb{sub 2}S{sub 15} with Ln = La and Nd are isostructural to Pr{sub 8}Sb{sub 2}S{sub 15} and crystallize in the tetragonal noncentrosymmetric space group I4{sub 1}cd. Their structure contains discrete [SbS{sub 3}]{sup 3-} trigonal pyramids separated by Ln{sup 3+} cations and S{sup 2-} anions. La{sub 8}Sb{sub 2}S{sub 15} shows second harmonic generation with intensities 1.2 times that of the commercially used IR NLO (nonlinear optics) material AgGaS{sub 2} (at 2.05 μm laser). It exhibits excellent thermal stability up to 663 C. Studies with UV/Vis-NIR diffuse reflectance spectroscopy show that La{sub 8}Sb{sub 2}S{sub 15} has an optical gap of around 2.3 eV, and a DFT study indicates a direct band gap with an electronic transfer excitation of S 3p electrons to a La 5d orbital. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Probing the magnetic and magnetothermal properties of M(II)-Ln(III) complexes (where M(II) = Ni or Zn; Ln(III) = La or Pr or Gd).

    Science.gov (United States)

    Ahmed, Naushad; Das, Chinmoy; Vaidya, Shefali; Srivastava, Anant Kumar; Langley, Stuart K; Murray, Keith S; Shanmugam, Maheswaran

    2014-12-14

    We establish the coordination potential of the Schiff base ligand (2-methoxy-6-[(E)-2'-hydroxymethyl-phenyliminomethyl]-phenolate (H2L)) via the isolation of various M(II)-Ln(III) complexes (where M(II) = Ni or Zn and Ln(III) = La or Pr or Gd). Single crystals of these five complexes were isolated and their solid state structures were determined by single crystal X-ray diffraction. Structural determination revealed molecular formulae of [NiGd(HL)2(NO3)3] (1), [NiPr(HL)2(NO3)3] (2) and [Ni2La(HL)4(NO3)](NO3)2 (3), [Zn2Gd(HL)4(NO3)](NO3)2 (4), and [Zn2Pr(HL)4(NO3)](NO3)2 (5). Complexes and were found to be neutral heterometallic dinuclear compounds, whereas 3-5 were found to be linear heterometallic trinuclear cationic complexes. Direct current (dc) magnetic susceptibility and magnetization measurements conclusively revealed that complexes 1 and 4 possess a spin ground state of S = 9/2 and 7/2 respectively. Empirically calculated ΔχMT derived from the variable temperature susceptibility data for all complexes undoubtedly indicates that the Ni(II) ion is coupled ferromagnetically with the Gd(III) ion, and antiferromagnetically with the Pr(III) ion in 1 and 2 respectively. The extent of the exchange interaction for was estimated by fitting the magnetic susceptibility data using the parameters (g = 2.028, S = 9/2, J = 1.31 cm(-1) and zJ = +0.007), supporting the phenomenon observed in an empirical approach. Similarly using a HDVV Hamiltonian, the magnetic data of 3 and 4 were fitted, yielding parameters g = 2.177, D = 3.133 cm(-1), J = -0.978 cm(-1), (for 3) and g = 1.985, D = 0.508 cm(-1) (for 4). The maximum change in magnetic entropy (-ΔSm) estimated from the isothermal magnetization data for was found to be 5.7 J kg(-1) K(-1) (ΔB = 7 Tesla) at 7.0 K, which is larger than the -ΔSm value extracted from 4 of 3.5 J kg(-1) K(-1) (ΔB = 7 Tesla) at 15.8 K, revealing the importance of the exchange interaction in increasing the overall ground state of a molecule for

  11. LN206井P110油管的腐蚀原因%Corrosion Reason of P110 Tubing Used in LN206 Well

    Institute of Scientific and Technical Information of China (English)

    毛学强; 谢俊峰; 宋文文; 周怀光; 赵密锋; 陈洪

    2013-01-01

    Severe corrosion occurred at thread joint between submersible pump and spill valve of P110 in LN206 well tubing after 43 days service.The reason of the corrosion failure was studied by metallographic examination,chemical composition analysis,and electrochemical test.The results indicated that to the tubing material,no abnormal phase was found according to micro-morphology observation chemical composition met the requirement of API Spec 5CT.The surface damage was observed on the thread,so the corrosive medium go into the crevice at the damage area.The electrochemical test results show that the potential difference between oil well tubing and spill valve is approximately 110 mV.It is concluded that the corrosion was mainly caused by crevice corrosion,galvanic corrosion,and the high concentration of Cl-accelerated the corrosion process.It is suggested to avoid thread damage during joining the oil well tubing and spill valve.It is necessary thread grease to fully fill the crevice between oil well tubing and spill valve avoid the direct contact of dissimilar metals with significant potential difference.%LN206井中P110油管与潜油泵出口处连接泄油阀的丝扣仅使用了43 d就发生严重腐蚀,对其进行了金相、化学分析和腐蚀电位测试.结果表明,油管的金相组织无异常,化学成分符合API Spec 5CT要求;且油管与泄油阀连接的丝扣有损伤现象,存在一定的缝隙,高浓度的Cl促进了腐蚀;油管的铬含量与泄油阀的相差较大,油管与泄油阀间的电位相差约110mV,电偶腐蚀加速丝扣处腐蚀.建议上扣时避免油管与泄油阀两者连接的丝扣发生损伤,并在丝扣上涂抹质量好的螺纹脂将两者丝扣间的缝隙填满,避免电位相差较大的异种材质直接连接.

  12. Kontinuální měření kvality páry

    OpenAIRE

    Rageh, Akram

    2014-01-01

    Diplomová práce se zabývá měřením, analýzou a následným nalezením vhodných fyzikálních parametrů pro analýzu kvality syté sterilizační páry. Tato práce si klade za cíl určit, kritické parametry systému vyvíječe páry pro provoz dle norem ČSN. Dílčí částí projektu je popis fyzikální sterilizace, syté páry, metod a senzorů pro kontrolu sterilizační páry. The diploma thesis deals with the measurement, analysis, and then finding the appropriate physical parameters for analyzing the quality of s...

  13. Kramers non-magnetic superconductivity in LnNiAsO superconductors.

    Science.gov (United States)

    Li, Yuke; Luo, Yongkang; Li, Lin; Chen, Bin; Xu, Xiaofeng; Dai, Jianhui; Yang, Xiaojun; Zhang, Li; Cao, Guanghan; Xu, Zhu-an

    2014-10-22

    We investigated a series of nickel-based oxyarsenides LnNiAsO (Ln=La, Ce, Pr, Nd, Sm) compounds. CeNiAsO undergoes two successive anti-ferromagnetic transitions at TN1=9.3 K and TN2=7.3 K; SmNiAsO becomes an anti-ferromagnet below TN≃3.5 K; NdNiAsO keeps paramagnetic down to 2 K but orders anti-ferromagnetically below TN≃1.3 K. Superconductivity was observed only in Kramers non-magnetic LaNiAsO and PrNiAsO with Tc=2.7 K and 0.93 K, respectively. The superconductivity of PrNiAsO is further studied by upper critical field and specific heat measurements, which reveal that PrNiAsO is a weakly coupled Kramers non-magnetic superconductor. Our work confirms that the nickel-based oxyarsenide superconductors are substantially different in mechanism to iron-based ones, and are likely to be described by the conventional superconductivity theory.

  14. Damage structure of austenitic stainless steel 316LN irradiated at low temperature in HFIR

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, N.; Robertson, J.P.; Grossbeck, M.L.; Rowcliffe, A.F. [Oak Ridge National Lab., TN (United States); Wakai, E. [Japan Atomic Energy Research Inst. (Japan)

    1998-03-01

    TEM disk specimens of austenitic stainless steel 316LN irradiated to damage levels of about 3 dpa at irradiation temperatures of either about 90 C or 250 C have been investigated by using transmission electron microscopy. The irradiation at 90 C and 250 C induced a dislocation loop density of 3.5 {times} 10{sup 22} m{sup {minus}3} and 6.5 {times} 10{sup 22} m{sup {minus}3}, a black dot density of 2.2 {times} 10{sup 23} m{sup {minus}3} and 1.6 {times} 10{sup 23} m{sup {minus}3}, respectively, in the steels, and a high density (<1 {times} 10{sup 22} m{sup {minus}3}) of precipitates in matrix. Cavities could be observed in the specimens after the irradiation. It is suggested that the dislocation loops, the black dots, and the precipitates cause irradiation hardening, an increase in the yield strength and a decrease in the uniform elongation, in the 316LN steel irradiated at low temperature.

  15. ln-Timişoara Molecular Activity Combined Models toward Interspecies Toxicity Assessment

    Science.gov (United States)

    Chicu, Sergiu A.; Putz, Mihai V.

    2009-01-01

    Aiming to provide a unified picture of computed activity – quantitative structure activity relationships, the so called Köln (ESIP-ElementSpecificInfluenceParameter) model for activity and Timisoara (Spectral-SAR) formulation of QSAR were pooled in order to assess the toxicity modeling and inter-toxicity correlation maps for aquatic organisms against paradigmatic organic compounds. The Köln ESIP model for estimation of a compound toxicity is based on the experimental measurement expressing the direct action of chemicals on the organism Hydractinia echinata so that the structural influence parameters are reflected by the metamorphosis degree itself. As such, the calculation of the structural parameters is absolutely necessary for correct evaluation and interpretation of the evolution of M(easured) and the C(computed) values. On the other hand, the Timişoara Spectral-SAR analysis offers correlation models and paths for H.e. species as well as for four other different organisms with which the toxicity may be inter-changed by means of the same mechanism of action induced by certain common chemicals. PMID:20057956

  16. The Uncommon Channel-Based Ln-MOFs for Highly Selective Fe(3+) Detection and Superior Rhodamine B Adsorption.

    Science.gov (United States)

    Xing, Shanghua; Bing, Qiming; Song, Lifei; Li, Guanghua; Liu, Jingyao; Shi, Zhan; Feng, Shouhua; Xu, Ruren

    2016-11-02

    Two new isostructural 3D lanthanide-organic frameworks [H2 N(Me)2 ] [Ln3 (OH)(bpt)3 (H2 O)3 ] (DMF)2 ⋅(H2 O)4 (1-Ln; Ln=Sm and Eu) with a 1D channel (25 Å) have been successfully assembled from the rare trinuclear [Ln3 (OH)(COO)9 ] clusters and biphenyl-3,4',5-tricarboxylic acid (H3 bpt) and exhibit high stability towards water in the pH range 3-10. MOF 1-Eu is a promising luminescent probe for sensing Fe(3+) in aqueous solution and is also selective towards rhodamine B (RhB) with a superior adsorption capacity of 735 mg g(-1) , which is the highest among the reported Ln-MOFs for RhB removal so far. Periodic DFT calculations further confirmed the selective adsorption of rhodamine B over other dyes. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Inorganic Speciation of Rare Earth Elements in Chaohu Lake and Longganhu Lake, East China

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Inorganic speciation of dissolved rare earth elements (REEs) were calculated for Chaohu Lake and Longganhu Lake by using the program MINTEQ 2. 30. The result shows that REE-Carbonate complexes, which account for more than 93 % of total REE are the dominate and typically species in solution. Moreover, carbonator complexes (LnCO3 +) were predicted to be the dominant species when pH between 7.2 and 8.0 and bicarbonate complexes (Ln (CO3)2-) were predicted to be the dominant species when pH > 8.0. The free ion specie (i. e., Ln3 + ) increases in these waters with pH decreasing and accounts for about 5. 03 %. The percentage of REE-phosphate complexes account for 1.61% of the dissolved REEs. REE-phosphate for light REEs complexes are supersaturated in Chaohu Lake and Longganhu Lake. Furthermore,LnPO4 for heavy REEs are supersaturated in west of Chaohu Lake in high water period. PO43- is responsible for limiting the dissolved REEs concentrations. REE-sulfate, REE-chloride, REE-fluoride and REE-hydroxide complexes, are negligible and generally account for less than 1% of the total dissolved REEs.

  18. Host composition dependent tunable multicolor emission in the single-phase Ba2(Ln1-zTbz)(BO3)2Cl:Eu phosphors

    NARCIS (Netherlands)

    Xia, Z.; Zhuang, J.; Meijerink, A.; Jing, X.

    2013-01-01

    A new strategy based on the host composition design has been adopted to obtain efficient color-tunable emission from Ba2Ln0.97−zTbz(BO3)2Cl:0.03Eu (Ln = Y, Gd and Lu, z = 0–0.97) phosphors. This study reveals that the single-phase Ba2Ln1−zTbz(BO3)2Cl compounds can be applied to use allowed Eu2+ abso

  19. Enhancement of superconductivity near the pressure-induced semiconductor-metal transition in the BiS₂-based superconductors LnO₀.₅F₀.₅BiS₂ (Ln = La, Ce, Pr, Nd).

    Science.gov (United States)

    Wolowiec, C T; White, B D; Jeon, I; Yazici, D; Huang, K; Maple, M B

    2013-10-23

    Measurements of electrical resistivity were performed between 3 and 300 K at various pressures up to 2.8 GPa on the BiS2-based superconductors LnO0.5F0.5BiS2 (Ln=Pr, Nd). At lower pressures, PrO0.5F0.5BiS2 and NdO0.5F0.5BiS2 exhibit superconductivity with critical temperatures Tc of 3.5 and 3.9 K, respectively. As pressure is increased, both compounds undergo a transition at a pressure Pt from a low Tc superconducting phase to a high Tc superconducting phase in which Tc reaches maximum values of 7.6 and 6.4 K for PrO0.5F0.5BiS2 and NdO0.5F0.5BiS2, respectively. The pressure-induced transition is characterized by a rapid increase in Tc within a small range in pressure of ∼0.3 GPa for both compounds. In the normal state of PrO0.5F0.5BiS2, the transition pressure Pt correlates with the pressure where the suppression of semiconducting behaviour saturates. In the normal state of NdO0.5F0.5BiS2, Pt is coincident with a semiconductor-metal transition. This behaviour is similar to the results recently reported for the LnO0.5F0.5BiS2 (Ln=La, Ce) compounds. We observe that Pt and the size of the jump in Tc between the two superconducting phases both scale with the lanthanide element in LnO0.5F0.5BiS2 (Ln=La, Ce, Pr, Nd).

  20. A new family of [Cu(II)Ln(III)M(V)] heterotrimetallic complexes (Ln = La, Gd, Tb; M = Mo, W): model systems to probe exchange interactions and single-molecule magnet properties.

    Science.gov (United States)

    Visinescu, Diana; Alexandru, Maria-Gabriela; Madalan, Augustin M; Jeon, Ie-Rang; Mathonière, Corine; Clérac, Rodolphe; Andruh, Marius

    2016-05-01

    Four isostructural trinuclear 3d-4f-4(5)d heterotrimetallic complexes, with the general formula [L(2)CuLn(H2O)5(μ-NC)M(CN)7], were obtained from the association of binuclear 3d-4f complexes and {M(V)(CN)8}(3-) metalloligands (M = Mo, Ln = La ; M = W, Ln = La ; M = Mo, Ln = Gd ; M = Mo; Ln = Tb , where H2L(2) = 1,2-ethanediylbis(2-iminomethylene-6-methoxy-phenol)). The metalloligand coordinates through a single-cyanido group at the apical position of the copper(ii) ion belonging to the {Cu(II)Ln(III)} binuclear complex. The analysis of the magnetic data for the La(iii) derivatives (compounds and ), in the 1.85-300 K temperature range, shows a weak ferromagnetic exchange interaction between Cu(II) and Mo(V)/W(V) ions across the cyanido bridge (JCuM/kB = 3.6(6) K; g = 2.23(5) for and JCuM/kB = 3.8(6) K, g = 2.21(5) for , with H = -2JCuMSCu·SM). These results were used to simulate the magnetic properties of compound , using the isotropic spin Hamiltonian H = -2JCuMoSCu·SMo - 2JCuGdSCu·SGd. The resulting magnetic interaction between Cu(II) and Gd(III) ions via the phenoxo-bridge was found to be weakly ferromagnetic (JCuGd/kB = +4.5(2) K with JCuMo/kB = +3.6(2) K, gGd = gCu = 2.00 and gMo = 1.98). The dc magnetic properties for compound also show a predominant ferromagnetic interaction, while the ac magnetic measurements indicate the presence of the slow relaxation of the magnetization below 3.5 K.

  1. Low-Temperature Sintering and Microwave Dielectric Properties of Bi0.9Ln0.05Li0.05V0.9Mo0.1O4 (Ln = Sm, Nd and La) Ceramics

    Science.gov (United States)

    Wang, Zixing; Yuan, Changlai; Yang, Tao; Feng, Qin; Liu, Fei; Chen, Jinman; Zhou, Changrong; Chen, Guohua

    2016-08-01

    Microwave dielectric ceramics of Bi0.9Ln0.05Li0.05V0.9Mo0.1O4 (Ln = Sm, Nd and La) with a low firing temperature were prepared via conventional solid-state reaction. The phases and microstructures of the ceramics were characterized by x-ray diffraction and scanning electron microscopy. The temperature coefficients of resonant frequency in the three compositions increased as sintering temperature increased. It is worth noting that a phase transition of the Bi0.9Ln0.05Li0.05V0.9Mo0.1O4 (Ln = Sm, Nd and La) ceramics from a monoclinic to a tetragonal scheelite structure was found with an increase in sintering temperature. The densification temperatures of all compositions were below 700°C. Excellent microwave dielectric properties were obtained for the Bi0.9Nd0.05Li0.05V0.9Mo0.1O4 ceramic sintered at 650°C, with a dielectric constant of ~72.2, a quality factor of ~6467 GHz and a temperature coefficient of resonant frequency of ~2.6 ppm/°C. The Bi0.9Ln0.05Li0.05V0.9Mo0.1O4 (Ln = Sm, Nd and La) ceramics are chemically compatible with both Ag and Cu powders at their sintering temperatures, and are thus a promising candidate for use in LTCC technology applications.

  2. Earth from Above

    Science.gov (United States)

    Stahley, Tom

    2006-01-01

    Google Earth is a free online software that provides a virtual view of Earth. Using Google Earth, students can view Earth by hovering over features and locations they preselect or by serendipitously exploring locations that catch their fascination. Going beyond hovering, they can swoop forward and even tilt images to make more detailed…

  3. Homometallic rare-Earth metal phosphinidene clusters: synthesis and reactivity.

    Science.gov (United States)

    Wang, Kai; Luo, Gen; Hong, Jianquan; Zhou, Xigeng; Weng, Linhong; Luo, Yi; Zhang, Lixin

    2014-01-20

    Two new trinuclear μ3 -bridged rare-earth metal phosphinidene complexes, [{L(Ln)(μ-Me)}3 (μ3 -Me)(μ3 -PPh)] (L=[PhC(NC6 H4 iPr2 -2,6)2 ](-) , Ln=Y (2 a), Lu (2 b)), were synthesized through methane elimination of the corresponding carbene precursors with phenylphosphine. Heating a toluene solution of 2 at 120 °C leads to an unprecedented ortho CH bond activation of the PhP ligand to form the bridged phosphinidene/phenyl complexes. Reactions of 2 with ketones, thione, or isothiocyanate show clear phospha-Wittig chemistry, giving the corresponding organic phosphinidenation products and oxide (sulfide) complexes. Reaction of 2 with CS2 leads to the formation of novel trinuclear rare-earth metal thione dianion clusters, for which a possible pathway was determined by DFT calculation. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Progress on Study of Luminescence of Rare Earth Organic Chelates

    Institute of Scientific and Technical Information of China (English)

    杨燕生; 安保礼; 龚孟濂; 史华红; 雷衡毅; 孟建新

    2002-01-01

    Based on the investigation of the luminescence of a series of rare earth organic chelates, some relationships between luminescence and the structure of the chelates were proposed: the intensity of sensitized luminescence of central lanthanide ions(Ln3+) in a rare earth organic chelate depends on (1)the suitability of the energy gap between the excited triplet energy level of the ligands and the lowest excited energy level of Ln3+ ions; (2)the rigidity and planarity of the structure of the chelate molecule; (3)the existence of a suitable secondary ligand which may increase rigidity and the stability of the chelate molecule; and (4) the existence of a suitable π-conjugated system in the chelate molecule. According to the above relationships, 25 novel organic ligands were designed and synthesized, and their lanthanide chelates were prepared. Investigation of the photoluminescence for the new chelates shows that some of the chelates are strongly luminescent, and are applied to fluoroimmunoassay for determination of human immunoglobulin(IgG), to preparation of fluorescent plastics, and to determination of growth hormone for plants. Two novel spectroscopy-probe techniques for structure of coordination compounds and biological molecules were proposed and developed based on vibronic spectroscopy of Tb3+ complexes and fluorescence of Ce3+.

  5. Rare Earth Resolution

    Institute of Scientific and Technical Information of China (English)

    Mei Xinyu

    2012-01-01

    BEFORE the early 1970s, China had no rare earth exports, and the world rare earth market was dominated by the United States, Europe and Japan. In the 1970s, China began to enter the world rare earth market and its share has picked up sharply in the following decades. Today, having the monopoly over global rare earth production, China must improve the benefits from rare earth production, not only from producing individual rare earth products, but also from mastering the intensive processing of rare earth products.

  6. Synthesis and characterization of K{sub 2}Ln{sub 2/3}Ta{sub 2}O{sub 7}·nH{sub 2}O (Ln= La, Pr, Nd), layered tantalates photo catalysts for water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Valencia S, H.; Tavizon, G. [UNAM, Instituto de Quimica, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Pfeiffer, H. [UNAM, Instituto de Investigaciones en Materiales, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Acosta, D. [UNAM, Instituto de Fisica, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Negron M, A., E-mail: hvalencia@utp.edu.co [UNAM, Instituto de Ciencias Nucleares, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico)

    2015-07-01

    Three compounds of the K{sub 2}Ln{sub 2/3}Ta{sub 2}O{sub 7} (Ln = La, Nd, Pr) cation-deficient Ruddlesden-Popper series were prepared by the Pechini (polymeric complex) method. The crystal structures of the hydrated form of these compounds were determined by Rietveld analysis of the X-ray power diffraction data and High Resolution Transmission Electron Microscopy (HRTEM). The samples were also analyzed to determine specific area (Bet), degree of hydration (Thermogravimetric analysis), and photo catalytic activity for hydrogen evolution from water and aqueous methanol solution. (Author)

  7. Site-selective fluorescence spectroscopy investigations of LnPO{sub 4} xenotime ceramics for radioactive waste disposal

    Energy Technology Data Exchange (ETDEWEB)

    Hirsch, A.; Peters, L. [RWTH Aachen Univ. (Germany). Inst. of Crystallography; Holthausen, J.; Neumeier, S. [Forschungszentrum Juelich (Germany); Huittinen, Nina [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes; Loesch, Henry

    2017-06-01

    Europium incorporation in different LnPO{sub 4} (Ln=Tb, Lu and Gd{sub 1-x}Lu{sub x}) phases crystallizing in the xenotime structure was investigated with site-selective TRLFS, PXRD and Rietveld analyses. Based on recorded emission spectra and diffraction patterns, the formation of three different crystal systems (xenotime, anhydrite, and monazite) could be identified. Aging of the ceramic samples and a second sintering step led to an accumulation of europium in the grain boundaries and on the surface.

  8. Influence of Heat Treatment on Mercury Cavitation Resistance of Surface Hardened 316LN Stainless Steel

    Energy Technology Data Exchange (ETDEWEB)

    Pawel, Steven J [ORNL; Hsu, Julia [Massachusetts Institute of Technology (MIT)

    2010-11-01

    The cavitation-erosion resistance of carburized 316LN stainless steel was significantly degraded but not destroyed by heat treatment in the temperature range 500-800 C. The heat treatments caused rejection of some carbon from the carburized layer into an amorphous film that formed on each specimen surface. Further, the heat treatments encouraged carbide precipitation and reduced hardness within the carburized layer, but the overall change did not reduce surface hardness fully to the level of untreated material. Heat treatments as short as 10 min at 650 C substantially reduced cavitation-erosion resistance in mercury, while heat treatments at 500 and 800 C were found to be somewhat less detrimental. Overall, the results suggest that modest thermal excursions perhaps the result of a weld made at some distance to the carburized material or a brief stress relief treatment will not render the hardened layer completely ineffective but should be avoided to the greatest extent possible.

  9. Martensitic Transformation during Fatigue Testing of an AISI 301LN Stainless Steel

    Science.gov (United States)

    Mateo, A.; Fargas, G.; Zapata, A.

    2012-02-01

    The plastic deformation accumulated during fatigue testing can induce the transformation of austenite to martensite in metastable austenitic stainless steels. To analyze this issue, a metastable austenitic stainless steel grade AISI 301 LN was studied in two different conditions, i.e. annealed and cold rolled. In the first case, the steel was fully austenitic, whereas cold rolled material had almost 30% of martensite. High cycle fatigue tests at a stress ratio of 0.8 were carried out on flat specimens from both steel conditions. Several characterization techniques, including optical microscopy, X-ray diffraction (XRD) and electron back scattered diffraction (EBSD), were used to detect and quantify the martensite induced by the cyclic deformation.

  10. Corrosion fatigue behaviour of 317LN austenitic stainless steel in phosphoric acid

    Energy Technology Data Exchange (ETDEWEB)

    Onoro, J. [Ingenieria y Ciencia de los Materiales, ETSI Industriales, Universidad Politecnica de Madrid, c/Jose Gutierrez Abascal, 2, 28006 Madrid (Spain)], E-mail: javier.onoro@upm.es

    2009-10-15

    The corrosion fatigue crack-growth behaviour of AISI 317LN stainless steel was evaluated in air and in 85% phosphoric acid at 20 deg. C. Austenitic stainless steels with high molybdenum content have high corrosion resistance and good mechanical properties. However, this increase in the molybdenum content and other elements such as nitrogen can also modify the microstructure. This leads to a modification of its mechanical properties. The corrosion fatigue crack-growth rate was higher in phosphoric acid immersion than in air. Austenitic stainless steels with a fully austenitic microstructure were more ductile, tough, and behave better against corrosion fatigue. The higher resistance to corrosion fatigue was directly associated to its higher resistance to corrosion.

  11. Study of ln s Physics in $\\bar{p}p$ Interactions at the Split Field Magnet

    CERN Multimedia

    2002-01-01

    This experiment uses the Split Field Magnet detector to investigate the low p^t, ``ln~s'', type of interactions that dominate the @*p cross-section. Systematic comparisons will be made to pp interactions. \\\\ \\\\ Specific areas to be studied include elastic scattering in the regions 0.05 $<$ !t! $<$ 0.8 GeV|2 and 0.8 $<$ !t! $<$ 4.0 GeV|2, and the use of a minimum bias trigger to study topological cross-sections, inclusive spectra, and two-body correlations. Some specialized triggers, run simultaneously with the high t elastic scattering trigger, are being studied. Examples are a trigger requiring Cerenkov identification in a limited region of phase space, and a trigger to select diffractively produced events.

  12. Theory of truth degrees of propositions in the logic system L*n

    Institute of Scientific and Technical Information of China (English)

    LI Jun; WANG Guojun

    2006-01-01

    By means of infinite product of uniformly distributed probability spaces of cardinal n the concept of truth degrees of propositions in the n-valued generalized Lukasiewicz propositional logic system L*n is introduced in the present paper. It is proved that the set consisting of truth degrees of all formulas is dense in [0,1], and a general expression of truth degrees of formulas as well as a deduction rule of truth degrees is then obtained. Moreover, similarity degrees among formulas are proposed and a pseudo-metric is defined therefrom on the set of formulas, and hence a possible framework suitable for developing approximate reasoning theory in n-valued generalized Lukasiewicz propositional logic is established.

  13. Thermomechanical and Isothermal Fatigue Behavior of 316LN Stainless Steel with Varying Nitrogen Content

    Science.gov (United States)

    Prasad Reddy, G. V.; Nagesha, A.; Sandhya, R.; Sankaran, S.; Mathew, M. D.; Bhanu Sankara Rao, K.

    2015-02-01

    Thermomechanical (TMF) and isothermal (IF) fatigue behavior of 316LN stainless steel alloyed with 0.07, 0.14, and 0.22 wt pct nitrogen is presented in this manuscript. In the TMF tests with temperature cycling in the range of 573 K to 873 K (300 °C to 600 °C), life decreased with increasing nitrogen content for both in-phase (IP) and out-of-phase (OP) cycling, with a peak at 0.07 wt pct N. In contrast, 0.14 wt pct N yielded maximum life under IF cycling carried out at 873 K (600 °C). Cyclic lives are seen to follow the sequence, IP-TMF < IF < OP-TMF cycling, and it remained same irrespective of the nitrogen content in 316LN SS. Lives under IP-TMF are lower than those in OP cycling by a factor of 2 to 2.5, in spite of the higher cyclic stress response in OP cycling. At all the nitrogen contents in the present study, nitrogen and dynamic strain aging induced slip localization in the form of planar slip bands both in IP and OP-TMF, in comparison to IF deformation wherein complete planar slip mode of deformation is evidenced only at 0.22 wt pct N. In TMF studies, increasing nitrogen content promoted strong slip localization ( i.e., increase in slip band density with a decrease in interband spacing) in combination with high tensile cyclic stresses that marred the beneficial effect of nitrogen content on TMF life.

  14. 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.

  15. Development of electrolyte-supported intermediate-temperature single-chamber solid oxide fuel cells using Ln 0.7Sr 0.3Fe 0.8Co 0.2O 3- δ (Ln = Pr, La, Gd) cathodes

    Science.gov (United States)

    Ruiz de Larramendi, I.; Lamas, D. G.; Cabezas, M. D.; Ruiz de Larramendi, J. I.; Walsöe de Reca, N. E.; Rojo, T.

    Iron-cobalt-based perovskite oxides with general formula Ln 0.7Sr 0.3Fe 0.8Co 0.2O 3- δ (where Ln = La, Pr and Gd) have been investigated for their application as intermediate-temperature cathodes in solid oxide fuel cells (SOFCs). Powdered samples of these materials were synthesized by a novel gel combustion process and then characterized by X-ray powder diffraction (XPD) and scanning electron microscopy (SEM). XPD patterns were satisfactorily indexed with an orthorhombic GdFeO 3-type structure and, for all samples, a mean particle size of less than 1 μm was estimated from the SEM data. Experimental single-chamber SOFCs using with these materials as cathodes and NiO-SDC (samaria-doped ceria) and SDC as anode and electrolyte, respectively, were evaluated at 600 °C in a methane/oxygen mixtures. Peak power densities of 65.4, 48.7 and 46.2 mW cm -2 were obtained for Ag|Ln 0.7Sr 0.3Fe 0.8Co 0.2O 3- δ|SDC|NiO-SDC|Pt cells with Ln = Pr, La and Gd, respectively. The relatively high power density obtained for the Pr compound shows that it could be an interesting material for cathode of single-chamber SOFCs.

  16. Solid state reaction synthesis and optical spectroscopy of ferroelectric (Gd{sub 1-x}Ln{sub x}){sub 2}(MoO{sub 4}){sub 3}; with Ln = Yb or Tm

    Energy Technology Data Exchange (ETDEWEB)

    Lin Zhoubin; Han Xiumei [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, c/Sor Juana Ines de la Cruz 3, 28049 Madrid (Spain); Zaldo, Carlos, E-mail: cezaldo@icmm.csic.e [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, c/Sor Juana Ines de la Cruz 3, 28049 Madrid (Spain)

    2010-03-04

    A solid state synthesis route was used to prepare (Gd{sub 1-x}Ln{sub x}){sub 2}(MoO{sub 4}){sub 3}, Ln = Yb or Tm, compounds with ferroelectric Pba2 crystal structure. It has been observed that this phase is the only one crystallized during 1123 K annealing for x {<=} 0.12 for Yb and x {<=} 0.3 for Tm. Above these concentration limits the simultaneous formation of trihydrated Ln{sub 2}(MoO{sub 4}){sub 3}, Ln = Yb or Tm, is observed. Up to these concentrations Yb and Tm incorporations do not degrade the SHG efficiency. The position of Yb{sup 3+} and Tm{sup 3+} energy levels involved in laser emission processes were determined by 5 K spectroscopy. The 300 K pumping and emission spectral distributions and excited level lifetime have been determined with the purpose of future applications as self-activated periodically poled ferroelectric laser and non-linear media.

  17. Synthesis, structure and ionic conductivity in scheelite type Li0.5Ce0.5−LnMoO4 ( = 0 and 0.25, Ln = Pr, Sm)

    Indian Academy of Sciences (India)

    Dipankar Saha; Giridhar Madras; Aninda J Bhattacharyya; Tayur N Guru Row

    2011-01-01

    Scheelite type solid electrolytes, Li0.5Ce0.5−LnMoO4 ( = 0 and 0.25, Ln = Pr, Sm) have been synthesized using a solid state method. Their structure and ionic conductivity () were obtained by single crystal X-ray diffraction and ac-impedance spectroscopy, respectively. X-ray diffraction studies reveal a space group of 41/ for Li0.5Ce0.5−LnMoO4 ( = 0 and 0.25, Ln = Pr, Sm) scheelite compounds. The unsubstituted Li0.5Ce0.5MoO4 showed lithium ion conductivity ∼ 10−5-10−3 −1cm-1 in the temperature range of 300-700°C ( = 2.5 × 10−3 −1cm-1 at 700°C). The substituted compounds show lower conductivity compared to the unsubstituted compound, with the magnitude of ionic conductivity being two (in the high temperature regime) to one order (in the low temperature regime) lower than the unsubstituted compound. Since these scheelite type structures show significant conductivity, the series of compounds could serve in high temperature lithium battery operations.

  18. Structural, dielectric and magnetic properties of Ba{sub 3}SrLn{sub 2}Fe{sub 2}Nb{sub 8}O{sub 30} (Ln = La, Nd, Sm) filled tungsten bronze ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wang [Laboratory of Dielectric Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027 (China); Yang, Wen Zhi [Laboratory of Dielectric Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027 (China); Ningbo Branch of China Academy of Ordnance Science, Ningbo, 315103 (China); Liu, Xiao Qiang [Laboratory of Dielectric Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027 (China); Chen, Xiang Ming, E-mail: xmchen59@zju.edu.cn [Laboratory of Dielectric Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027 (China)

    2016-08-05

    Structural, dielectric and magnetic properties have been investigated for Ba{sub 3}SrLn{sub 2}Fe{sub 2}Nb{sub 8}O{sub 30} (Ln = La, Nd, Sm) ceramics. The single phase tetragonal filled tungsten bronze structure in space group P4/mbm is obtained for Ba{sub 3}SrLa{sub 2}Fe{sub 2}Nb{sub 8}O{sub 30}, while such tungsten bronze major phase is determined together with minor amount of secondary phases in Ba{sub 3}SrNd{sub 2}Fe{sub 2}Nb{sub 8}O{sub 30} and Ba{sub 3}SrSm{sub 2}Fe{sub 2}Nb{sub 8}O{sub 30}. The saturated magnetic hysteresis loops with enhanced M{sub r} are obtained in the present ceramics at room temperature comparing to the Ba{sub 4}Ln{sub 2}Fe{sub 2}Nb{sub 8}O{sub 30} (Ln = La, Nd, Sm) ceramics. Meanwhile, the typical relaxor behaviors are determined: a broad dielectric peak with strong frequency dispersion and the peak temperature following well with the Vogel–Fulcher relationship. - Highlights: • The tetragonal filled tungsten bronze structure in space group P4/mbm is obtained. • The typical relaxor behaviors are determined. • The magnetic hysteresis loops with enhanced Mr are obtained at room temperature.

  19. Rethinking Sensitized Luminescence in Lanthanide Coordination Polymers and MOFs: Band Sensitization and Water Enhanced Eu Luminescence in [Ln(C15H9O5)3(H2O)3]n (Ln = Eu, Tb).

    Science.gov (United States)

    Einkauf, Jeffrey D; Kelley, Tanya T; Chan, Benny C; de Lill, Daniel T

    2016-08-15

    A coordination polymer [Ln(C15H9O9)3(H2O)3]n (1-Ln = Eu(III), Tb(III)) assembled from benzophenonedicarboxylate was synthesized and characterized. The organic component is shown to sensitize lanthanide-based emission in both compounds, with quantum yields of 36% (Eu) and 6% (Tb). Luminescence of lanthanide coordination polymers is currently described from a molecular approach. This methodology fails to explain the luminescence of this system. It was found that the band structure of the organic component rather than the molecular triplet state was able to explain the observed luminescence. Deuterated (Ln(C15H9O9)3(D2O)3) and dehydrated (Ln(C15H9O9)3) analogues were also studied. When bound H2O was replaced by D2O, lifetime and emission increased as expected. Upon dehydration, lifetimes increased again, but emission of 1-Eu unexpectedly decreased. This reduction is reasoned through an unprecedented enhancement effect of the compound's luminescence by the OH/OD oscillators in the organic-to-Eu(III) energy transfer process.

  20. The Lifeworld Earth and a Modelled Earth

    Science.gov (United States)

    Juuti, Kalle

    2014-01-01

    The goal of this paper is to study the question of whether a phenomenological view of the Earth could be empirically endorsed. The phenomenological way of thinking considers the Earth as a material entity, but not as an object as viewed in science. In the learning science tradition, tracking the process of the conceptual change of the shape of the…

  1. The Lifeworld Earth and a Modelled Earth

    Science.gov (United States)

    Juuti, Kalle

    2014-01-01

    The goal of this paper is to study the question of whether a phenomenological view of the Earth could be empirically endorsed. The phenomenological way of thinking considers the Earth as a material entity, but not as an object as viewed in science. In the learning science tradition, tracking the process of the conceptual change of the shape of the…

  2. Low temperature synthesis of fluorite-type Ce-based oxides of composition Ln₂Ce₂O₇ (Ln = Pr, Nd and Eu): photodegradation and Luminescence studies

    Indian Academy of Sciences (India)

    M MALATHI; K SREENU; GUNDEBOINA RAVI; P VIJAYA KUMAR; CH SUDHAKAR REDDY; RAVINDER GUJE; RADHA VELCHURI; M VITHAL

    2017-08-01

    In this work, we have studied the structural behavior of Fluortie-type (F-type) Ce-based oxides of compositions Ln₂Ce₂O₇ (Ln = Pr, Nd and Eu). F-type oxides can be considered as multi-functional materials due to the deficiency of anions. Pr₂Ce₂O₇ (PCO), Nd₂Ce₂O₇ (NCO) and Eu₂Ce₂O₇ (ECO) were prepared by ethylene glycol-assisted sol–gel method. The structural investigation of these oxides was carried out by Powder XRD and Rietveld refinement. All the materials were found to crystallize in the cubic lattice with space group $Fm\\bar{3}m$. Raman spectra of these materials are reliable with their XRD data. The morphology and bandgap energy of all the samples were obtained from SEM and KM plot, respectively. The visible light photocatalytic performance of these oxides was examined against the degradation of methylene blue under ambient conditions. The photoluminescence property of the rare earth ionswas also studied, and the color coordinates were calculated using CIE 1931 chromaticity.

  3. Nano-to millisecond lifetime luminescence properties in Ln{sub 2}(WO{sub 4}){sub 3} (Ln = La, Ho, Tm and Eu) microcrystalline powders with different crystal structures

    Energy Technology Data Exchange (ETDEWEB)

    Lahoz, F. [Departamento de Física, Universidad de La Laguna, Avda. Astrofísico Francisco Sánchez, S/N, 38206 La Laguna, Tenerife (Spain); Sabalisck, N.P., E-mail: nanprado@ull.edu.es [Departamento de Física, Universidad de La Laguna, Avda. Astrofísico Francisco Sánchez, S/N, 38206 La Laguna, Tenerife (Spain); Cerdeiras, E.; Mestres, L. [Grup de Química de l' Estat Sòlid, Departament de Química Inorgànica, Universitat de Barcelona, 08028 Barcelona (Spain)

    2015-11-15

    Ln{sub 2}(WO{sub 4}){sub 3} crystals (Ln = La, Ho, Tm, Eu) have been synthesized using the conventional solid-state ceramic technique. X-ray diffraction was employed to identify the crystal structure of the compounds. Depending on the ionic radii of RE{sup 3+}, two different structures are found, α-Eu{sub 2}(WO{sub 4}){sub 3} (modulated scheelite-type) or γ-Sc{sub 2}(WO{sub 4}){sub 3} (phase with negative thermal expansion coefficient). The optical characterization is based on absorption, photoluminescence, excitation and kinetic decay studies. Under UV excitation at the (WO{sub 4}){sup 2−} absorption band, two different behaviors are recorded. La{sub 2}(WO{sub 4}){sub 3} compounds show a broad visible emission band with a nanosecond range decay rate, and no energy transfer (ET) from the (WO{sub 4}){sup 2−} moiety to the lanthanide ion is observed. However, evidences of ET are observed for Ln = Tm, Ho and Eu. In particular, the (WO{sub 4}){sup 2−} → Eu{sup 3+} ET is so high that the fluorescence of the (WO{sub 4}){sup 2−} moiety is almost completely quenched. Consequently, upon UV excitation Eu{sub 2}(WO{sub 4}){sub 3} provides an intense visible emission with a 120 μs day lifetime. Although (WO{sub 4}){sup 2−} → Ln{sup 3+} ET also occurs for Ln = Ho and Tm, the relatively small energy gap between energy levels of these ions avoids any detectable luminescence, which is quenched by multiphonon processes. Moreover, the effect of a structural phase transition in Ho{sub 2}(WO{sub 4}){sub 3} crystals on their luminescence properties is analyzed. The broad range of PL response of Ln{sub 2}(WO{sub 4}){sub 3} under UV excitation both in the spectral position of the emission bands (from UV to visible) as well as in the decay range (from ns to hundreds of μs) shows the tunability of wolframates for scintillator applications. - Highlights: • .A wide range of PL properties were observed in Ln{sub 2}(WO{sub 4}){sub 3} compounds depending on Ln. • The PL

  4. Perovskite-Like Polar Lanthanide Formate Frameworks of [NH2NH3][Ln(HCOO)4] (Ln = Tb-Lu and Y): Synthesis, Structures, Magnetism, and Anisotropic Thermal Expansion.

    Science.gov (United States)

    Zhao, Tian-Meng; Chen, Sa; Shang, Ran; Wang, Bing-Wu; Wang, Zhe-Ming; Gao, Song

    2016-10-17

    A series of isostructural hydrazinium lanthanide (Ln) formate framework compounds of [NH2NH3][Ln(HCOO)4] for Ln(3+) ions from Tb(3+) to Lu(3+) and Y(3+) have been successfully prepared by utilizing NH2NH3(+). The compounds crystallize in orthorhombic polar space group Pca21, with cell parameters at 180 K of a = 18.2526(7)-18.1048(5) Å, b = 6.5815(2)-6.5261(2) Å, c = 7.6362(3)-7.5044(2) Å, and V = 917.33(6)-886.67(4) Å(3), showing the effect of lanthanide contraction. The compounds possess polar perovskite-like structures incorporating the hydrazinium cations in the cavities of the NaCl-like framework, in which the Ln(3+) ions in a bicapped trigonal prism are connected by anti-anti and syn-anti formate groups. The N-H···Oformate hydrogen-bonding interactions are between the hydrazinium cations and the anionic framework. One anti-anti formate group is frustrated by the competitive N-H···Oformate hydrogen-bonding interactions. It thus twists or flips upon warming, resulting in large anisotropic thermal expansion and negative thermal expansion below 180 K. A comparison with the transition metal and magnesium analogues revealed that the structural compactness, tighter binding of the hydrazinium cation by the framework, and symmetrically better match between the framework and ammonium cation for Ln compounds could inhibit the occurrence of phase transition in the series. The IR spectroscopic, thermal, and magnetic properties are investigated.

  5. High-pressure investigations of lanthanoid oxoarsenates. I. Single crystals of scheelite-type Ln[AsO{sub 4}] phases with Ln = La-Nd from monazite-type precursors

    Energy Technology Data Exchange (ETDEWEB)

    Metzger, Sebastian J.; Ledderboge, Florian; Schleid, Thomas [Stuttgart Univ. (Germany). Inst. fuer Anorganische Chemie; Heymann, Gunter; Huppertz, Hubert [Innsbruck Univ. (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie

    2016-08-01

    Transparent single crystals of the scheelite-type Ln[AsO{sub 4}] phases with Ln = La-Nd are obtained by the pressure-induced monazite-to-scheelite type phase transition in a Walker-type module under high-pressure and high-temperature conditions of 11 GPa at 1100-1300 C. Coinciding with this transition, there is an increase in density and a reduction in molar volume of about 4.5 % for the scheelite-type phases (tetragonal, I4{sub 1}/a) for La[AsO{sub 4}] (a = 516.92(4), c = 1186.1(9) pm), Ce[AsO{sub 4}] (a = 514.60(1), c = 1175.44(2) pm), Pr[AsO{sub 4}] (a = 512.63(4), c = 1168.25(9) pm), and Nd[AsO{sub 4}] (a = 510.46(4), c = 1160.32(11) pm) as compared to the well-known monazite-type phases (monoclinic, P2{sub 1}/n). Surprisingly enough, the scheelite-type oxoarsenates(V) exhibit a lower coordination number for the Ln{sup 3+} cations (CN = 8 versus CN = 8 + 1), whereas the isolated tetrahedral [AsO{sub 4}]{sup 3-} anions (d(As-O) = 168.9-169.3 pm for the scheelites as compared to d(As-O) = 167.1-169.9 pm for the monazites) remain almost unchanged. So the densification must occur because of the loss of two edge-connections of the involved [LnO{sub 8+1}]{sup 15-} polyhedra with the [AsO{sub 4}]{sup 3-} tetrahedra in the monazite- resulting in exclusively vertex connected [LnO{sub 8}]{sup 13-} and [AsO{sub 4}]{sup 3-} units in the scheelite-type structure.

  6. Four-shell polyoxometalates featuring high-nuclearity Ln{sub 26} clusters. Structural transformations of nanoclusters into frameworks triggered by transition-metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhong; Li, Xin-Xiong; Yang, Tao; Cai, Zhen-Wen; Zheng, Shou-Tian [State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fujian (China)

    2017-03-01

    A series of polyoxometalates (POMs) that incorporate the highest-nuclearity Ln clusters that have been observed in such structures to date (Ln{sub 26}, Ln=La and Ce) are described, which exhibit giant multishell configurations (Ln is contained in W{sub 6} is contained in Ln{sub 26} is contained in W{sub 100}). Their structures are remarkably different from known giant POMs that feature multiple Ln ions. In particular, the incorporated Ln-O clusters with a nuclearity of 26 are significantly larger than known high-nuclearity (≤10) Ln-O clusters in POM chemistry. Furthermore, they also contain the largest number of La and Ce centers for any POM reported to date and represent a new kind of rare giant POMs with more than 100 W atoms. Interestingly, the La{sub 26}-containing POM can undergo a single-crystal to single-crystal structural transformation in the presence of various transition-metal ions, such as Cu{sup 2+}, Co{sup 2+}, and Ni{sup 2+}, from an inorganic molecular nanocluster into an inorganic-organic hybrid extended framework that is built from POM building blocks with even higher-nuclearity La{sub 28} clusters bridged by transition-metal complexes. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Boiling phenomenon due to quasi-steadily and rapidly increasing heat inputs in LN 2 and LHe I

    Science.gov (United States)

    Sakurai, A.; Shiotsu, M.; Hata, K.

    Dynamic boiling processes, including the transition from a single-phase non-boiling regime to film boiling caused by exponentially increasing heat inputs, Q 0e t/τ for a wide range of periods and pressures on horizontal wires in LN 2 and LHe I were investigated. The main problem is that there are no active cavities on the wire surfaces for initial boiling in the liquids. The heat transfer processes due to increasing heat inputs with increasing rates ranging from quasi-steady to rapidly increasing ones in LN 2 were classified into three types for the pressures. The dynamic boiling processes in LHe I due to rapidly increasing heat inputs at the pressures tested here correspond to Type 3 processes including semi-direct transitions in LN 2 at pressures higher than about 1 MPa. The lower limit temperatures of boiling initiation on the wire surfaces for initial boiling in liquids at pressures due to quasi-steadily increasing heat inputs are clearly lower than the homogeneous spontaneous nucleation temperatures corresponding to these pressures. Liquid superheat close to the solid surface in LHe I was evaluated from the value of the wire surface temperature, taking off the temperature drop due to Kapitza resistance. The initial boiling temperatures due to quasi-steady heat inputs at pressures in saturated LN 2 and LHe I agreed with the values derived from the theoretical model based on the heterogeneous spontaneous nucleation in flooded cavities on the solid surface.

  8. Effect of simvastatin on expression of IL17, HMGB1 and TLR4 in LN kidney tissues of rats

    Institute of Scientific and Technical Information of China (English)

    Ying Qin; Ya-Ting Sun; Lin-Xia Xia; Ying-Jie Zhang; Xue-Jun Yang

    2014-01-01

    Objective:To observe the intervention influence and effect of simvastatin on the expression of interleukin17(LI17), high mobility group protein1(HMGB1) andTLR4 path inLupus nephritis (LN) rats.Methods:A total of28BSXSB male mice withLN(16 weeks) were randomly divided into observation group and the comparison group, observation group was given6 mg•kg-1•d-1 simvastatin in0.1%PBS lavage for4 weeks, the comparison group was not given any treatment. Blood urea nitrogen(BUN) level and urine trace albumin(Scr) level of two groups were determined. The expression ofIL17,HMGB1 andTLR4 protein was detected using immune histochemical method, and the kidney histological damage was observed.Results:BNU,LI17,HMGB1,TLR4 protein andHMGB1 mRNA in observation group was significantly lower than that in control group (P0.05).Histological observation showed glomerular lesions integral of observation group was obviously lower than that of control group.Conclusions:Simvastatin can reduce the expression ofIL17,HMGB1 and TLR4 protein inLN mice, thereby can inhibit the autoimmune response as a potential treatment function ofLN.

  9. Design Guidelines for Collaboration and Participation with Examples from the LN4LD (Learning Network for Learning Design)

    NARCIS (Netherlands)

    Burgos, Daniel; Hummel, Hans; Tattersall, Colin; Brouns, Francis; Koper, Rob

    2007-01-01

    Burgos, D., Hummel, H. G. K., Tattersall, C., Brouns, F., & Koper, R. (2009). Design Guidelines for Collaboration and Participation with Examples from the LN4LD (Learning Network for Learning Design). In L. Lockyer, S. Bennett, S. Agostinho & B. Harper (Eds.), Handbook of Research on Learning Design

  10. 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.

  11. EarthKAM

    Data.gov (United States)

    National Aeronautics and Space Administration — Sponsored by NASA, EarthKAM (Earth Knowledge Acquired by Middle School Students) is an educational outreach program allowing middle school students to take pictures...

  12. Earth on the Move.

    Science.gov (United States)

    Naturescope, 1987

    1987-01-01

    Provides background information on the layers of the earth, the relationship between changes on the surface of the earth and its insides, and plate tectonics. Teaching activities are included, with some containing reproducible worksheets and handouts to accompany them. (TW)

  13. NASA Earth Exchange (NEX)

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA Earth Exchange (NEX) represents a new platform for the Earth science community that provides a mechanism for scientific collaboration and knowledge sharing....

  14. Syntheses, Characterizations and Catalytic Activities of Rare Earth Derivatives of Molybdotungstovanado-Phosphoric Heteropoly Acid

    Institute of Scientific and Technical Information of China (English)

    周百斌; 韦永德; 马慧媛; 王玉和; 单永奎

    2002-01-01

    Seven new-type pentabasic heteropoly complexes with the general molecular formula K10H5[Ln(PMo5W4V2O39)2]*nH2O(Ln=La, Ce, Pr, Nd, Eu, Gd, Dy) were synthesized. The results of IR, UV, 31P, 51V NMR and X-ray powder diffraction pattern demonstrate that the product still maintains Keggin structure. The thermal stability studied by water solubility test, TG-DTA, XRD and IR at various temperature shows that the range of pyrolysis temperature is from 500~550 ℃. The catalytic action varies according to the contents of rare earths which are used to catalyze the decomposition of hydrogen peroxide.

  15. Synthesis and catalytic activity of Ln(III) complexes with an unsymmetrical Schiff base including multi()C = N-groups

    Institute of Scientific and Technical Information of China (English)

    姚克敏; 李宁; 沈联芳

    2003-01-01

    A synthetic method for a new unsymmetrical Schiff base and its Ln (III) complexes including multi C == N- groups is reported. The complexes are characterized by elemental analysis, IR spectra, 1H and 13C NMR, especially 2D-COSY1H, 1H NMR spectra. The general formula of the obtained complexes is [Ln3(TBLY)(NO3)3]@nH2O (Ln = La, n = 3; Ln = Nd, n = 5; Ln = Gd, Dy, Yb, Y, n = 7), whereTBLY = tetraglycol aldehyde-2,4-dihydroxy benzaldehyde bis-lysine Schiff base. In addition, the evidence for existence of C == CH-NH- group is supported bythe AM1 method. The complexes obtained may be used as a catalyst. Conversion rate of 80% with the viscosity-average molecular weight 220000 for the polymerization of methyl methacrylate (MMA) without addition of any cocatalyst has been obtained.

  16. Homoleptic rare-earth metal(III) tetramethylaluminates: structural chemistry, reactivity, and performance in isoprene polymerization.

    Science.gov (United States)

    Zimmermann, Melanie; Frøystein, Nils Age; Fischbach, Andreas; Sirsch, Peter; Dietrich, H Martin; Törnroos, Karl W; Herdtweck, Eberhardt; Anwander, Reiner

    2007-01-01

    The complexes [Ln(AlMe4)3] (Ln=Y, La, Ce, Pr, Nd, Sm, Ho, Lu) have been synthesized by an amide elimination route and the structures of [Lu{(micro-Me)2AlMe2}3], [Sm{(micro-Me)2AlMe2}3], [Pr{(micro-Me)2AlMe2}3], and [La{(micro-Me)2AlMe2}2{(micro-Me)3AlMe}] determined by X-ray crystallography. These structures reveal a distinct Ln3+ cation size-dependency. A comprehensive insight into the intrinsic properties and solution coordination phenomena of [Ln(AlMe4)3] complexes has been gained from extended dynamic 1H and 13C NMR spectroscopic studies, as well as 1D 89Y, 2D 1H/89Y, and 27Al NMR spectroscopic investigations. [Ce(AlMe4)3] and [Pr(AlMe4)3] have been used as alkyl precursors for the synthesis of heterobimetallic alkylated rare-earth metal complexes. Both carboxylate and siloxide ligands can be introduced by methane elimination reactions that give the heterobimetallic complexes [Ln{(O2CAriPr)2(micro-AlMe2)}2(AlMe4)(C6H14)n] and [Ln{OSi(OtBu)3}(AlMe3)(AlMe4)2], respectively. [Pr{OSi(OtBu)3}(AlMe3)(AlMe4)2] has been characterized by X-ray structure analysis. All of the cerium and praseodymium complexes are used as precatalysts in the stereospecific polymerization of isoprene (1-3 equivalents of Et2AlCl as co-catalyst) and compared to the corresponding neodymium-based initiators reported previously. The superior catalytic performance of the homoleptic complexes leads to quantitative yields of high-cis-1,4-polyisoprene (>98%) in almost all of the polymerization experiments. In the case of the binary catalyst mixtures derived from carboxylate or siloxide precatalysts quantitative formation of polyisoprene is only observed for nLn:nCl=1:2. The influence of the metal size is illustrated for the heterobimetallic lanthanum, cerium, praseodymium, neodymium, and gadolinium carboxylate complexes, and the highest activities are observed for praseodymium as a metal center in the presence of one equivalent of Et2AlCl.

  17. A crystal chemical study on the superconductivity and compressibility of LnFePnO (Pn = P, As) superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Li, Huaiyong, E-mail: huaiyong.lee@gmail.com [School of Materials Science and Engineering, Liaocheng University, Liaocheng 252000 (China); Wu, Zhijian; Zhou, Shihong [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Zhang, Siyuan, E-mail: syzhang@ciac.jl.cn [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Pu, Xipeng; Yao, Shujuan; Wang, Xiaoqing; Yin, Jie [School of Materials Science and Engineering, Liaocheng University, Liaocheng 252000 (China)

    2015-05-25

    Graphical abstract: The covalency fraction increases in an order of Ln–O < Ln–Pn < Fe–Pn, which favors the electron transfer from LnO layer to FePn layer, At the same time, the Ln–O bonds have a higher lattice energy density as well as bulk modulus than the Fe–Pn bonds in the compounds. As a result, either doping F{sup −} ions or increase the external pressure leads to an increase in the covalency fraction gradient. This also favors the electron transfer. - Highlights: • Bonding characters of Ln–O, Ln–Pn and Fe–Pn bonds were calculated. • Lattice energy density and bulk modulus of Ln–O bonds are higher than those of Fe–Pn. • Doping F{sup −} ions or increase the external pressure leads to an increase in the covalency gradient. - Abstract: The discovery of superconductivity transition in LnFePnO (Pn = P, As) compounds is of great importance in exploring new superconductors as well as understanding the mechanism. In this paper, the bonding characters in LnFePnO compounds and their relationship to the superconductivity at ambient pressure and under external pressure have been studied. The results show that the covalency of the chemical bonds is in an increased order of Ln–O < Ln–Pn < Fe–Pn, and this order favors the electron transfer from LnO layers to FePn layers. It is also calculated that the LnO layers are less compressible than the FePn layers. Applying an external pressure to the compounds, or doping F{sup −} in O{sup 2−} site will increase the covalency gradient among the layers, and thus lead to a higher superconductivity transition temperature.

  18. A family of acetato-diphenoxo triply bridged dimetallic Zn(II)Ln(III) complexes: SMM behavior and luminescent properties.

    Science.gov (United States)

    Oyarzabal, Itziar; Artetxe, Beñat; Rodríguez-Diéguez, Antonio; García, JoséÁngel; Seco, José Manuel; Colacio, Enrique

    2016-06-21

    Eleven dimetallic Zn(II)-Ln(III) complexes of the general formula [Zn(µ-L)(µ-OAc)Ln(NO3)2]·CH3CN (Ln(III) = Pr (1), Nd (2), Sm (3), Eu (4), Gd (5), Tb (6), Dy (7), Ho (8), Er (9), Tm (10), Yb (11)) have been prepared in a one-pot reaction from the compartmental ligand N,N'-dimethyl-N,N'-bis(2-hydroxy-3-formyl-5-bromo-benzyl)ethylenediamine (H2L). In all these complexes, the Zn(II) ions occupy the internal N2O2 site whereas the Ln(III) ions show preference for the O4 external site. Both metallic ions are bridged by an acetate bridge, giving rise to triple mixed diphenoxido/acetate bridged Zn(II)Ln(III) compounds. The Nd, Dy, Er and Yb complexes exhibit field induced single-ion magnet (SIM) behaviour, with Ueff values ranging from 14.12 to 41.55 K. The Er complex shows two relaxation processes, but only the second relaxation process with an energy barrier of 21.0 K has been characterized. The chromophoric L(2-) ligand is able to act as an "antenna" group, sensitizing the near-infrared (NIR) Nd(III) and Yb(III)-based luminescence in complexes 2 and 11 and therefore, both compounds can be considered as magneto-luminescent materials. In addition, the Sm(III), Eu(III) and Tb(III) derivatives exhibit characteristic emissions in the visible region.

  19. 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.

  20. Research on anti-corrosion property of rare earth inhibitor for X70 steel

    Institute of Scientific and Technical Information of China (English)

    ZHU Yanhua; ZHUANG Jia; YU Yongsheng; ZENG Xianguang

    2013-01-01

    Three kinds of rare earth nitrates were adopted to sodium molybdate to get three kinds of LnN-M compounded inhibitors (La(NO3)3+Na2MoO4(LaN-M),Ce(NO3)3+Na2MoO4(CeN-M),Pr(NO3)3+Na2MoO4(PrN-M)).The combination of weight-loss method and the electrochemical test,was used to evaluate and analyze the corrosion inhibition efficiency of these LnN-M inhibitors to make the research on their corrosion inhibition performance,and the sequential order of their performance was found as follows:CeN-M> LaN-M>PrN-M,among which,the inhibition efficiency of CeN-M for the X70 steel could reach 98.21%.The synergism parameters were calculated by weight-loss method,these computational data indicated that the synergistic effect between rare earth nitrates and sodium molybdate was obvious and significant.Surface morphology,chemical composition and phase components of the precipitation films were tested for discussing the mechanism of LnN-M inhibitors.The outer electronic configuration of the lanthanide was found to have an important influence on the inhibition efficiency.The CeN-M inhibitor was discovered to have the best inhibition effect with the amorphous cerium oxides.The results of this research revealed that the precipitation films formed on the surface of the steel samples had a crucial influence on the inhibition efficiencies after adding LnN-M inhibitors.

  1. Reaction of (CP(2)asterisk-lnH)(2) (ln=Y, La) and CP(2)asterisk-Y(2-C(6)H(4)CH(2)NMe(2)) with esters and amides and molecular-structure of [CP(2)asterisk-Y(mu- ocme=chc(oet)o)](2)

    NARCIS (Netherlands)

    Deelman, B.J; Wierda, F.; Meetsma, A.; Teuben, J.H

    1995-01-01

    The activation of esters and amides by (Cp(2)*LnH)(2) [Ln = Y (1a), Ln = La (1b), Cp*=C(5)Me] and Cp(2)*Y(2-C(6)H(4)CH(2)NMe(2)) (2) is described. Compounds 1a and 1b react with ethyl acetate to form Cp(2)*YOEt (3a) and Cp(2)*LaOEt (30). With 1a and ethyl benzoate a 1:1 mixture of 3a and

  2. Capturing Near Earth Objects

    OpenAIRE

    Baoyin, Hexi; CHEN Yang; Li, Junfeng

    2011-01-01

    Recently, Near Earth Objects (NEOs) have been attracting great attention, and thousands of NEOs have been found to date. This paper examines the NEOs' orbital dynamics using the framework of an accurate solar system model and a Sun-Earth-NEO three-body system when the NEOs are close to Earth to search for NEOs with low-energy orbits. It is possible for such an NEO to be temporarily captured by Earth; its orbit would thereby be changed and it would become an Earth-orbiting object after a small...

  3. Red emitting phosphors of Eu{sup 3+} doped Na{sub 2}Ln{sub 2}Ti{sub 3}O{sub 10} (Ln = Gd, Y) for white light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Niumiao [National Key Laboratory of Photoelectric Technology and Functional Materials Culture Base in Shaanxi Province, National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Institute of Photonics & Photon-Technology, Northwest University, Xi’an 710069 (China); Guo, Chongfeng, E-mail: guocf@nwu.edu.cn [National Key Laboratory of Photoelectric Technology and Functional Materials Culture Base in Shaanxi Province, National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Institute of Photonics & Photon-Technology, Northwest University, Xi’an 710069 (China); Yin, Luqiao; Zhang, Jianhua [Key Laboratory of Advanced Display and System Applications (Shanghai University), Ministry of Education, Shanghai 200072 (China); Wu, Mingmei, E-mail: ceswmm@mail.sysu.edu.cn [School of Chemistry and Chemical Engineering, Sun Yat-Sen University, No. 135, Xingang Xi Road, Guangzhou 510275 (China)

    2015-06-25

    Highlights: • Layered red phosphors Na{sub 2}Ln{sub 2}Ti{sub 3}O{sub 10} (Ln = Gd, Y):Eu{sup 3+} were prepared. • The synthesis parameters of phosphors were optimized. • PL and thermal stability of the samples were investigated. • LED devices were also fabricated including the present red phosphor. - Abstract: A series of Eu{sup 3+} doped Na{sub 2}Ln{sub 2}Ti{sub 3}O{sub 10} (Ln = Gd, Y) red-emitting phosphors for application in ultraviolet based light emitting diodes (LEDs) were successfully synthesized by a modified sol–gel method. Their structure and luminescent properties were characterized by powder X-ray diffraction (XRD), photoluminescence excitation (PLE) and emission (PL) spectra and absorption spectra, according to these results the optimal compositions and synthesis parameters were determined. In addition, the thermal stabilities of the phosphors were investigated according to the temperature-dependent PL spectra. The red and white-LEDs (W-LEDs) comprising the Na{sub 2}Ln{sub 2}Ti{sub 3}O{sub 10}:Eu{sup 3+} (Ln = Gd, Y) red emitting phosphors were fabricated with a near-ultraviolet (n-UV) chip. In comparison with Na{sub 2}Y{sub 1.4}Eu{sub 0.6}Ti{sub 3}O{sub 10}, the Na{sub 2}Gd{sub 0.6}Eu{sub 1.4}Ti{sub 3}O{sub 10} phosphor offers higher brightness, quantum efficiency, and excellent thermal stability. W-LEDs comprising Na{sub 2}Gd{sub 0.6}Eu{sub 1.4}Ti{sub 3}O{sub 10} showed bright white emission with a color rendering index (Ra) of 82, a color temperature of 2151 K, and Commission Internationale de I’Eclairage (CIE) color coordinates of (0.34, 0.37). The phosphor Na{sub 2}Gd{sub 0.6}Eu{sub 1.4}Ti{sub 3}O{sub 10} is more suitable candidate for application in LEDs.

  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. Heptanuclear lanthanide [Ln7] clusters: from blue-emitting solution-stable complexes to hybrid clusters.

    Science.gov (United States)

    Canaj, Angelos B; Tsikalas, George K; Philippidis, Aggelos; Spyros, Apostolos; Milios, Constantinos J

    2014-09-07

    The use of LH3 (2-(β-naphthalideneamino)-2-hydroxymethyl-1-propanol) and aibH (2-amino-isobutyric acid) in 4f chemistry has led to the isolation of eight new isostructural lanthanide complexes. More specifically, the reaction of the corresponding lanthanide nitrate salt with LH3 and aibH in MeOH, under solvothermal conditions in the presence of NEt3, led to the isolation and characterization of seven complexes with the general formulae [Ln(III)7(OH)2(L')9(aib)]·4MeOH (Ln = Gd, ·4MeOH; Tb, ·4MeOH; Dy, ·4MeOH; Ho, ·4MeOH; Er, ·4MeOH; Tm, ·4MeOH; Yb, ·4MeOH L' = the dianion of the Schiff base between naphthalene aldehyde and 2-amino-isobutyric acid). Furthermore, the isostructural Y(III) analogue, cluster [Y(III)7(OH)2(L')9(aib)]·4MeOH (·4MeOH), was synthesized in a similar manner to . The structure of all eight clusters describes a distorted [M(III)6] octahedron which encapsulates a seventh M(III) ion in an off-centre fashion. Dc magnetic susceptibility studies in the 5-300 K range for complexes reveal the presence of dominant antiferromagnetic exchange interactions within the metallic clusters as evidenced by the negative Weiss constant, θ, while ac magnetic susceptibility measurements show temperature and frequency dependent out-of-phase signals for the [Dy(III)7] analogue (·4MeOH), suggesting potential single molecule magnetism character. Furthermore, for complex , simulation of its dc magnetic susceptibility data yielded very weak antiferromagnetic interactions within the metallic centres. Solid-state emission studies for all clusters display ligand-based emission, while extended 1D and 2D NMR studies for ·4MeOH reveal that the species retain their structural integrity in solution. In addition, TGA measurements for , and revealed excellent thermal stability up to 340 °C for the clusters.

  6. 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.

  7. Physicochemical Properties of Near-Linear Lanthanide(II) Bis(silylamide) Complexes (Ln = Sm, Eu, Tm, Yb).

    Science.gov (United States)

    Goodwin, Conrad A P; Chilton, Nicholas F; Vettese, Gianni F; Moreno Pineda, Eufemio; Crowe, Iain F; Ziller, Joseph W; Winpenny, Richard E P; Evans, William J; Mills, David P

    2016-10-17

    Following our report of the first near-linear lanthanide (Ln) complex, [Sm(N(††))2] (1), herein we present the synthesis of [Ln(N(††))2] [N(††) = {N(Si(i)Pr3)2}; Ln = Eu (2), Tm (3), Yb (4)], thus achieving approximate uniaxial geometries for a series of "traditional" Ln(II) ions. Experimental evidence, together with calculations performed on a model of 4, indicates that dispersion forces are important for stabilization of the near-linear geometries of 1-4. The isolation of 3 under a dinitrogen atmosphere is noteworthy, given that "[Tm(N″)(μ-N″)]2" (N″ = {N(SiMe3)2}) has not previously been structurally authenticated and reacts rapidly with N2(g) to give [{Tm(N″)2}2(μ-η(2):η(2)-N2)]. Complexes 1-4 have been characterized as appropriate by single-crystal X-ray diffraction, magnetic measurements, electrochemistry, multinuclear NMR, electron paramagnetic resonance (EPR), and electronic spectroscopy, along with computational methods for 3 and 4. The remarkable geometries of monomeric 1-4 lead to interesting physical properties, which complement and contrast with comparatively well understood dimeric [Ln(N″)(μ-N″)]2 complexes. EPR spectroscopy of 3 shows that the near-linear geometry stabilizes mJ states with oblate spheroid electron density distributions, validating our previous suggestions. Cyclic voltammetry experiments carried out on 1-4 did not yield Ln(II) reduction potentials, so a reactivity study of 1 was performed with selected substrates in order to benchmark the Sm(III) → Sm(II) couple. The separate reactions of 1 with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), azobenzene, and benzophenone gave crystals of [Sm(N(††))2(TEMPO)] (5), [Sm(N(††))2(N2Ph2)] (6), and [Sm(N(††)){μ-OPhC(C6H5)CPh2O-κO,O'}]2 (7), respectively. The isolation of 5-7 shows that the Sm(II) center in 1 is still accessible despite having two bulky N(††) moieties and that the N-donor atoms are able to deviate further from linearity or ligand

  8. An anti CuO2-type metal hydride square net structure in Ln2M2As2H(x) (Ln=La or Sm, M=Ti, V, Cr, or Mn).

    Science.gov (United States)

    Mizoguchi, Hiroshi; Park, SangWon; Hiraka, Haruhiro; Ikeda, Kazutaka; Otomo, Toshiya; Hosono, Hideo

    2015-03-02

    Using a high pressure technique and the strong donating nature of H(-), a new series of tetragonal La2Fe2Se2O3-type layered mixed-anion arsenides, Ln2M2As2H(x), was synthesized (Ln=La or Sm, M=Ti, V, Cr, or Mn; x≈3). In these compounds, an unusual M2H square net, which has anti CuO2 square net structures accompanying two As(3-) ions, is sandwiched by (LaH)2 fluorite layers. Notably, strong metal-metal bonding with a distance of 2.80 Å was confirmed in La2Ti2As2H2.3, which has metallic properties. In fact, these compounds are situated near the boundary between salt-like ionic hydrides and transition-metal hydrides with metallic characters.

  9. Synthesis and luminescent properties of novel pyrazolone rare earth complexes

    Institute of Scientific and Technical Information of China (English)

    BAO Jiqing; TANG Chunhua; TANG Ruiren

    2011-01-01

    A novel pyrazolone pyridine-containing ligand,2,6-bis(l-phenyl-4-ethoxycarbonyl-5-pyrazolone-3-yl)pyridine(H2L)was designed and synthesized from Pyridine-2,6-dicarboxylic acid(1),and its Eu(Ⅲ)and Tb(Ⅲ)complexes were prepared.The 1igand and complexes were characterized in detailbased on FT-IR spectra,1H NMR,elemental ahalysis and thermal analysis,and the formula of Ln2L3·4H2O(Ln=Eu or Tb)of rare earth complexes was confirmed.The UV-vis absorption spectm and photoluminescence properties of the complexes were investigated,which showed that the Eu(Ⅲ)and Tb(Ⅲ)ions could be sensitized efficiently by the ligand(H2L)and emit the photoluminescence with high intensity, narrow half-peak width,and monochromic light.The results indicated that the complexes showed potential as excellent luminescent materials.

  10. Z phase stability in AISI 316LN + Nb austenitic steels during creep at 650 C

    Energy Technology Data Exchange (ETDEWEB)

    Vodarek, Vlastimil [Technical Univ. Ostrava (Czech Republic)

    2010-07-01

    The creep resistance of austenitic CrNi(Mo) steels strongly depends on microstructural stability during creep exposure. Nitrogen additions to CrNi(Mo) austenitic steels can significantly improve the creep strength. One of the most successful methods of improving the long-term creep resistance of austenitic steels is based on increasing the extent of precipitation strengthening during creep exposure. The role of precipitates in the achievements of good creep properties has been extensively studied for a long time. Although many minor phases are now well documented there are still contractions and missing thermodynamic data about some minor phases. This contribution deals with results of microstructural studies on the minor phase evolution in wrought AISI 316LN niobium stabilised steels during long-term creep exposure at 650 C. Microstructural investigations were carried out on specimens taken from both heads and gauge lengths of ruptured test-pieces by means of optical metallography, transmission and scanning electron microscopy. The attention has been paid to evaluation of thermodynamic and dimensional stability of Z phase and other nitrogen bearing minor phases. Only two nitrogen-bearing minor phases formed in the casts investigated: Z phase and M{sub 6}X. The dimensional stability of Z phase particles was very high. (orig.)

  11. Optimization of hybrid laser - TIG welding of 316LN steel using response surface methodology (RSM)

    Science.gov (United States)

    Ragavendran, M.; Chandrasekhar, N.; Ravikumar, R.; Saxena, Rajesh; Vasudevan, M.; Bhaduri, A. K.

    2017-07-01

    In the present study, the hybrid laser - TIG welding parameters for welding of 316LN austenitic stainless steel have been investigated by combining a pulsed laser beam with a TIG welding heat source at the weld pool. Laser power, pulse frequency, pulse duration, TIG current were presumed as the welding process parameters whereas weld bead width, weld cross-sectional area and depth of penetration (DOP) were considered as the process responses. Central composite design was used to complete the design matrix and welding experiments were conducted based on the design matrix. Weld bead measurements were then carried out to generate the dataset. Multiple regression models correlating the process parameters with the responses have been developed. The accuracy of the models were found to be good. Then, the desirability approach optimization technique was employed for determining the optimum process parameters to obtain the desired weld bead profile. Validation experiments were then carried out from the determined optimum process parameters. There was good agreement between the predicted and measured values.

  12. Z phase stability in AISI 316LN + Nb austenitic steels during creep at 650 C

    Energy Technology Data Exchange (ETDEWEB)

    Vodarek, Vlastimil [Technical Univ. Ostrava (Czech Republic)

    2010-07-01

    The creep resistance of austenitic CrNi(Mo) steels strongly depends on microstructural stability during creep exposure. Nitrogen additions to CrNi(Mo) austenitic steels can significantly improve the creep strength. One of the most successful methods of improving the long-term creep resistance of austenitic steels is based on increasing the extent of precipitation strengthening during creep exposure. The role of precipitates in the achievements of good creep properties has been extensively studied for a long time. Although many minor phases are now well documented there are still contractions and missing thermodynamic data about some minor phases. This contribution deals with results of microstructural studies on the minor phase evolution in wrought AISI 316LN niobium stabilised steels during long-term creep exposure at 650 C. Microstructural investigations were carried out on specimens taken from both heads and gauge lengths of ruptured test-pieces by means of optical metallography, transmission and scanning electron microscopy. The attention has been paid to evaluation of thermodynamic and dimensional stability of Z phase and other nitrogen bearing minor phases. Only two nitrogen-bearing minor phases formed in the casts investigated: Z phase and M{sub 6}X. The dimensional stability of Z phase particles was very high. (orig.)

  13. Effects of Different Forging Processes on Microstructure Evolution for 316LN Austenitic Stainless Steel

    Science.gov (United States)

    Sui, Dashan; Zhu, Lingling; Wang, Tao; Zhang, Peipei; Cui, Zhenshan

    2017-07-01

    Forging experiments were designed and carried out on a 3150 kN hydraulic press to investigate the effects of different processes on the microstructure evolution for 316LN steel. The forging processes included single-pass (upsetting) and multipass (stretching) deformations, and the experimental results indicated that the average grain size varied with forging processes. Moreover, the size had distinct differences at different positions in the workpiece. Meanwhile, numerical simulations were implemented to study the influence of temperature, strain, and strain rate on microstructure evolution. The results of experiments and simulations comprehensively demonstrated that dynamic, static, and meta-dynamic recrystallization could coexist in the hot forging process and that the recrystallization process could easily occur under the conditions of higher temperature, larger strain, and higher strain rate. Moreover, the temperature had more significant influence on both recrystallization and grain growth. A higher temperature could not only promote the recrystallization but also speed up the grain growth. Therefore, a lower temperature is beneficial to obtain refinement grains on the premise that the recrystallization can occur completely.

  14. Pairing in the BCS and LN approximations using continuum single particle level density

    Science.gov (United States)

    Id Betan, R. M.; Repetto, C. E.

    2017-04-01

    Understanding the properties of drip line nuclei requires to take into account the correlations with the continuum spectrum of energy of the system. This paper has the purpose to show that the continuum single particle level density is a convenient way to consider the pairing correlation in the continuum. Isospin mean-field and isospin pairing strength are used to find the Bardeen-Cooper-Schrieffer (BCS) and Lipkin-Nogami (LN) approximate solutions of the pairing Hamiltonian. Several physical properties of the whole chain of the Tin isotope, as gap parameter, Fermi level, binding energy, and one- and two-neutron separation energies, were calculated and compared with other methods and with experimental data when they exist. It is shown that the use of the continuum single particle level density is an economical way to include explicitly the correlations with the continuum spectrum of energy in large scale mass calculation. It is also shown that the computed properties are in good agreement with experimental data and with more sophisticated treatment of the pairing interaction.

  15. Enhanced mechanical properties of type AISI301LN austenitic stainless steel through advanced thermo mechanical process

    Energy Technology Data Exchange (ETDEWEB)

    Huang Junxia, E-mail: huangjunxia@baosteel.com [Shanghai Baosteel Research Institute, Shanghai 200431 (China); Ye Xiaoning; Gu Jiaqing; Chen Xu [Shanghai Baosteel Research Institute, Shanghai 200431 (China); Xu Zhou [School of Material Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer 69% of strain induced martensite were obtained after 80% thickness reduction at 0 Degree-Sign C. Black-Right-Pointing-Pointer The best annealing regime was determined for diffusional controlled reversion. Black-Right-Pointing-Pointer The effect of grain size on mechanical properties conforms with the H-P relationship. - Abstract: The effect of annealing temperature and time on the grain size of reversed austenite and mechanical properties was studied based on AISI301LN austenitic stainless steel in this paper. Cold rolling at 0 Degree-Sign C was employed to obtain the strain-induced martensite, followed by annealing treatment at the temperature range of 650-900 Degree-Sign C for 1-20 min. The relationship between the volume fraction of strain-induced martensite and cold reduction was analyzed by Ferritescope MP30 and X-ray diffraction. The grain growth of reversed austenite was observed by FEG-SEM and the mechanical properties were determined by tensile tests and Vickers hardness tests. Austenite grain sizes under 3 {mu}m can be obtained after annealing in the range of 700-900 Degree-Sign C for 1-20 min. The finest austenite grain size was produced after annealing at 700 Degree-Sign C for 20 min, which had a good combination of yield strength ( Almost-Equal-To 830 MPa), tensile strength ( Almost-Equal-To 953 MPa) and elongation ( Almost-Equal-To 36%).

  16. Pairing in the BCS and LN approximations using continuum single particle level density

    Energy Technology Data Exchange (ETDEWEB)

    Id Betan, R.M., E-mail: idbetan@ifir-conicet.gov.ar [Instituto de Física Rosario (CONICET-UNR), Bv. 27 de Febrero 210 bis, S2000EZP Rosario (Argentina); Facultad de Ciencias Exactas, Ingeniería y Agrimensura (UNR), Av. Pellegrini 250, S2000BTP Rosario (Argentina); Instituto de Estudios Nucleares y Radiaciones Ionizantes (UNR), Riobamba y Berutti, S2000EKA Rosario (Argentina); Repetto, C.E. [Instituto de Física Rosario (CONICET-UNR), Bv. 27 de Febrero 210 bis, S2000EZP Rosario (Argentina); Facultad de Ciencias Exactas, Ingeniería y Agrimensura (UNR), Av. Pellegrini 250, S2000BTP Rosario (Argentina)

    2017-04-15

    Understanding the properties of drip line nuclei requires to take into account the correlations with the continuum spectrum of energy of the system. This paper has the purpose to show that the continuum single particle level density is a convenient way to consider the pairing correlation in the continuum. Isospin mean-field and isospin pairing strength are used to find the Bardeen–Cooper–Schrieffer (BCS) and Lipkin–Nogami (LN) approximate solutions of the pairing Hamiltonian. Several physical properties of the whole chain of the Tin isotope, as gap parameter, Fermi level, binding energy, and one- and two-neutron separation energies, were calculated and compared with other methods and with experimental data when they exist. It is shown that the use of the continuum single particle level density is an economical way to include explicitly the correlations with the continuum spectrum of energy in large scale mass calculation. It is also shown that the computed properties are in good agreement with experimental data and with more sophisticated treatment of the pairing interaction.

  17. Corrosion Fatigue Behavior of 316LN SS in Acidified Sodium Chloride Solution at Applied Potential

    Science.gov (United States)

    Poonguzhali, A.; Pujar, M. G.; Mallika, C.; Mudali, U. Kamachi

    2015-05-01

    The influence of acidified 1 M NaCl solution by addition of 2 ml/L of HCl on the cyclic plastic deformation of AISI Type 316LN SS containing 0.07 wt.% and 0.22 wt.% N was investigated as a function of the applied potentials. The corrosion fatigue (CF) behavior of stainless steel (SS) was explained vis-a-vis the dislocation behavior, the propensity to form microcracks, and the evolution of the current transients based on the studies carried out at both room-temperature and boiling conditions. CF experiments were conducted using round tensile specimens at a stress ratio of 0.5 and a frequency of 0.1 Hz. Two different kinds of damage mechanisms were observed (I) the damage mechanism in the stable-passive state was correlated with the localization of the anodic dissolution due to a depassivation-repassivation process, whereas (II) the cyclic stress induced pitting corrosion in the metastable pitting state, which resulted in formation of microcracks. The study of the microcracking process and its evolution is a key to the physical mechanism by which the fatigue life of stainless steels would be affected in an aqueous corrosive solution under the applied potential.

  18. Flux of Nitrogen-13 from L-(N-13)Glutamate in isolated myocardium

    Energy Technology Data Exchange (ETDEWEB)

    Keen, R.E.; Barrio, J.R.; Krivokapich, J.; Phelps, M.E.

    1985-05-01

    Specific activity of nitrogen-13 containing metabolites in tissue and effluent was determined following an intra-arterial bolus of non-carrier added L-(N-13)glutamate (N-13 GLU) given to isolated rabbit septa under different metabolic states which include pyruvate (2 mM), transaminase inhibition (aminooxy-acetate, AOA, 2 mM), or pyruvate with AOA superimposed on the insulin and glucose perfused septa. Six minutes after the N-13 GLU bolus administration relative tissue specific activities of glutamine, alanine, aspartate, and glutamate were approximately 3:38:52:100, respectively, in the control and pyruvate perfused septa. The lower alanine specific activity when compared with control tissue indicated that alanine output was from a pool separate from GPT alanine pools. Higher glutamate specific activity suggested that its output is from a pool(s) different than the larger intra-cellular glutamate pool(s). All interventions with AOA blocked N-13 flux through transminases altering tissue and effluent relative specific activities with increase in % N-13 and specific activities for glutamine, glutamate, ammonia, and protein concomittant with disappearance of labeled aspartate and alanine. These results indicate that N-13 distribution in myocardium after N-13 GLU administration is mainly controlled by glutamate interaction with reversible transaminases. The differences in reactant (N-13 GLU) and product specific activities are a consequence of channeling between different cytosolic and mitochondrial glutamate microcompartments.

  19. Effect of the addition of rare earths on the activity of alumina supported copper cobaltite in CO oxidation, CH4 oxidation and NO decomposition

    Institute of Scientific and Technical Information of China (English)

    B Ivanov; I Spassova; M Milanova; G Tyuliev; M Khristova

    2015-01-01

    The effect of the addition of small amounts of rare earths (Ln=La, Ce, Nd and Gd) to alumina supported copper-cobalt spinel oxide on the catalysts efficiency in CO and CH4 oxidation and in NO decomposition was investigated. Samples of Ln/CuCo/Al catalyst were prepared and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic absorption spectroscopy (AAS), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), H2-temperature-programmed reduc-tion (H2-TPR), electron paramagnetic resonance (EPR) spectroscopy and low temperature nitrogen adsorption. The results showed that the addition of rare earths changed the surface state of the alumina supported copper-cobalt spinel catalyst. As a result, partial re-duction of copper species was observed as well as migration of these species between the surface and the bulk. The Ln/CuCo/Al catalysts behaved differently in oxidation and reduction processes. In oxidation processes where oxide structure was important, Ce/CuCo/Al and Nd/CuCo/Al were the most active catalysts. The catalyst Ce/CuCo/Al was the most active in the oxidation reactions because of the availability and favorable surface distribution of the redox couples Cu+/Cu2+ and Ce3+/Ce4+. In NO decompostion, Ln-modified catalysts significantly improved the selectivity of the process to N2.

  20. Synthesis, Structure, and Physical Properties of Ln(Cu,Al,Ga)13-x (Ln = La-Pr, and Eu) and Eu(Cu,Al)13-x

    Energy Technology Data Exchange (ETDEWEB)

    Phelan, W Adam; Kangas, Michael J; McCandless, Gregory T; Drake, Brenton L; Haldolaarachchige, Neel; Zhao, Liang L; Wang, Jiakui K; Wang, Xiaoping P; Young, David P; Morosan, Emilia; Hoffmann, Christina; Chan, Julia Y [LSU; (Rice); (ORNL)

    2012-09-10

    Ln(Cu,Al,Ga)13–x (Ln = La–Pr, and Eu; x ~ 0.2) were synthesized by a combined Al/Ga flux. Single crystal X-ray and neutron diffraction experiments revealed that these compounds crystallize in the NaZn13 structure-type (space group Fm3⁻c) with lattice parameters of a ~ 12 Å, V ~ 1600 Å, and Z ~ 8. Our final neutron models led us to conclude that Cu is occupationally disordered on the 8b Wyckoff site while Cu, Al, and Ga are substitutionally disordered on the 96i Wyckoff site of this well-known structure-type. The magnetic susceptibility data show that Ce(Cu,Al,Ga)13–x and Pr(Cu,Al,Ga)13–x exhibit paramagnetic behavior down to the lowest temperatures measured while Eu(Cu,Al,Ga)13–x displays ferromagnetic behavior below 6 K. Eu(Cu,Al)13–x was prepared via arc-melting and orders ferromagnetically below 8 K. The magnetocaloric properties of Eu(Cu,Al,Ga)13–x and Eu(Cu,Al)13–x were measured and compared. Additionally, an enhanced value of the Sommerfeld coefficient (γ = 356 mJ/mol-K2) was determined for Pr(Cu,Al,Ga)13–x. Herein, we present the synthesis, structural refinement details, and physical properties of Ln(Cu,Al,Ga)13–x (Ln = La–Pr, and Eu) and Eu(Cu,Al)13–x.

  1. Water Exchange on [Ln(DO3A)(H2O)2] and [Ln(DTTA-Me)(H2O)2](-) Studied by Variable Temperature, Pressure, and Magnetic Field NMR.

    Science.gov (United States)

    Karimi, Shima; Helm, Lothar

    2016-05-02

    Water exchange kinetics of [Ln(L)(H2O)2](x) complexes (Ln = Pr, Nd, Dy, Tm, and Yb; L = DO3A and DTTA-Me) were studied by (17)O NMR spectroscopy as a function of temperature, pressure, and frequency and by (1)H nuclear magnetic relaxation dispersion. Water exchange rate constants of both complexes show a maximum at dysprosium. Water exchange on negatively charged complexes of the acyclic DTTA-Me ligand is much faster than on the neutral complexes of the macrocyclic DO3A. Small activation volumes |ΔV(⧧)| studied. In the case of [Ln(DTTA-Me)(H2O)2](-), a change in mechanism is detected from a dissociative mechanism (D, ΔV(⧧) = 7 cm(3) mol(-1)) for complexes with larger ions (Pr to Gd) to an interchange mechanism (Id, I; ΔV(⧧) = +1.8 and +0.4 cm(3) mol(-1)) for complexes with smaller ions (Dy and Tm).

  2. Lanthanide triangles sandwiched by tetranuclear copper complexes afford a family of hendecanuclear heterometallic complexes [Ln(III)3Cu(II)8] (Ln = La-Lu): synthesis and magnetostructural studies.

    Science.gov (United States)

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

    2013-08-05

    Reaction in ethanol of 3-hydroxymethylen-5-methylsalicylaldoxime (H3L) with CuCl2·2H2O and LnCl3·xH2O [Ln = La (1), Ce (2), Pr (3), Nd (4), Eu (5), Gd (6), Tb (7), Dy (8), Er (9), Yb (10), Lu (11), Ho (12)] allowed the synthesis of a family of hendecanuclear heterometallic copper(II)-lanthanide(III) clusters with general formula [Ln(III)3Cu(II)8(HL)6(μ4-O)2Cl6(H2O)8]Cl3 (1-12). According to the single-crystal X-ray diffraction investigation, the complexes are isomorphous and crystallize in the trigonal R32 group. The hendecanuclear cluster is formed by two tetrahedral μ4-oxo {Cu4} clusters assembled by three lanthanide ions sandwiched in between. Along the family, the separation between the {Cu4} moieties increases linearly from Lu to La in good correlation with ionic radius of the lanthanide ions. A comparative analysis of the magnetic data for the lanthanum (1) and lutetium (11) compounds shows the presence of ferromagnetic and antiferromagnetic interactions within the μ4-oxo {Cu4} moieties. For the gadolinium (6) and terbium (7) compounds, the magnetic interactions between the lanthanide and the copper ions are found to be ferromagnetic. The dysprosium (8) compound exhibits single-molecule magnet behavior.

  3. Twinned CsLn{sub 2}F{sub 7} compounds (Ln=Nd, Gd, Tb, Er, Yb). The role of a highly symmetrical cation lattice with an arrangement analogous to the Laves phase MgZn{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Friese, Karen [Forschungszentrum Juelich GmbH, Juelich (Germany). Juelich Centre for Neutron Science-2; Khaidukov, Nicholas [Kurnakov Institute of General and Inorganic Chemistry, Moscow (Russian Federation); Grzechnik, Andrzej [RWTH Aachen Univ. (Germany). Inst. for Crystallography

    2016-07-01

    The occurrence of twinning can often be related to higher symmetrical structures. Fluorides are frequently twinned due to their close relation to high symmetry structures like fluoride, tysonite or pyrochlores. The series of compounds CsLn{sub 2}F{sub 7} is no exception. We refined the structures of the twinned compounds with Ln=Nd, Gd, Tb, Er, Yb in space group P112{sub 1}/b. An analysis of the pseudosymmetry of the resulting structures shows a highly symmetrical cation partial structure with a cation distribution similar to the one in the hexagonal Laves phase MgZn{sub 2}. Several other compounds ALn{sub 2}F{sub 7}, which have been described in the literature, show a similar cation array. The diversity of different space groups which have been reported for ALn{sub 2}F{sub 7} compounds can be better understood using group-subgroup relationships assuming the hypothetical structure of the cation array with space group P6{sub 3}/mmc as aristotype. Furthermore, the twinning is easily understood on the basis of the lost symmetry operations in the symmetry reduction from point group 6/mmm, e.g. to 2/m in the case of the CsLn{sub 2}F{sub 7} compounds.

  4. The structures and luminescence properties of lanthanide (Ln = Sm, Eu and Tb) metal-organic coordination polymers based on 5-(2-hydroxyethoxy)isophthalate ligand

    Science.gov (United States)

    Wang, Peng; Zhang, Yu-Jie; Qin, Jie; Chen, Yong; Zhao, Ying

    2015-03-01

    Three unreported isomorphous Ln-containing metal-organic coordination polymeric complexes {LnL(HL)ṡ(H2O)2}n (Ln = Sm (1), Eu (2) and Tb (3), CCDC 971815-971817) were synthesized based on 5-(2-hydroxyethoxy) isophthalic acid (H2L) under hydrothermal conditions. The obtained coordination polymers were characterized by IR, elemental analysis, thermal analysis and X-ray diffraction In solid state, these polymers featured 3-D supramolecular structures constructed by 2-D sheets through H-bonds. Investigation of photoluminescence properties of H2L and 1-3 showed all of them exhibited intense fluorescent emissions in the solid state at room temperature.

  5. The Earth's Magnetic Field

    OpenAIRE

    Edda Lína Gunnarsdóttir 1988

    2012-01-01

    The Earth's magnetic field is essential for life on Earth, as we know it, to exist. It forms a magnetic shield around the planet, protecting it from high energy particles and radiation from the Sun, which can cause damage to life, power systems, orbiting satellites, astronauts and spacecrafts. This report contains a general overview of the Earth's magnetic field. The different sources that contribute to the total magnetic field are presented and the diverse variations in the field are describ...

  6. Uderstanding Snowball Earth Deglaciation

    Science.gov (United States)

    Abbot, D. S.

    2012-12-01

    Earth, a normally clement planet comfortably in its star's habitable zone, suffered global or nearly global glaciation at least twice during the Neoproterozoic era (at about 635 and 710 million years ago). Viewed in the context of planetary evolution, these pan-global glaciations (Snowball Earth events) were extremely rapid, lasting only a few million years. The dramatic effect of the Snowball Earth events on the development of the planet can be seen through their link to rises in atmospheric oxygen and evolutionary innovations. These potential catastrophes on an otherwise clement planet can be used to gain insight into planetary habitability more generally. Since Earth is not currently a Snowball, a sound deglaciation mechanism is crucial for the viability of the Snowball Earth hypothesis. The traditional deglaciation mechanism is a massive build up of CO2 due to reduced weathering during Snowball Earth events until tropical surface temperatures reach the melting point. Once initiated, such a deglaciation might happen on a timescale of only dozens of thousands of years and would thrust Earth from the coldest climate in its history to the warmest. Therefore embedded in Snowball Earth events is an even more rapid and dramatic environmental change. Early global climate model simulations raised doubt about whether Snowball Earth deglaciation could be achieved at a CO2 concentration low enough to be consistent with geochemical data, which represented a potential challenge to the Snowball Earth hypothesis. Over the past few years dust and clouds have emerged as the essential missing additional processes that would allow Snowball Earth deglaciation at a low enough CO2 concentration. I will discuss the dust and cloud mechanisms and the modeling behind these ideas. This effort is critical for the broader implications of Snowball Earth events because understanding the specific deglaciation mechanism determines whether similar processes could happen on other planets.

  7. La islamofobia como recurso político: el caso pro-Köln (PRO-NRW

    Directory of Open Access Journals (Sweden)

    Guerrero Enterría, Arturo

    2008-12-01

    Full Text Available This article seeks to analyse, from the case study of the Pro-Köln party, how Islamophobia is used as a resource by some parties on the extreme right in Europe to obtain political returns and electoral support. Using an analysis of the genesis of the party and its electoral program as a starting point, the study dismantles theargument that this party’s main objective is to fight against the Islamisation of Europe, and shows that this is only one means to articulate an ultra-rightist political discourse and that its attempt to stop the construction of the mosque in Köln is only window-dressing to conquer the votes of the citizenry.

  8. Nitrogen segregation and blister formation of 316LN austenitic steel during electron beam welding tests for ITER gravity supports

    Science.gov (United States)

    Lee, P. Y.; Hou, B. L.; Wu, J. H.; Yang, D.; Zhang, G. R.; Zhang, C. P.

    2009-04-01

    316LN has been widely applied in the design of ITER components, such as shield blanket and gravity supports, due to its excellent corrosion resistance and high strength. The behavior of nitrogen in this steel during welding is important for the mechanical properties of the components. In this study, a focused 150 kv high voltage electron beam with 300 mA beam current has been used to weld 316LN steel under vacuum condition. The microstructure and composition of the welding area were observed and analyzed. The influence of welding on the shock resistance and tensile strength at both room temperature and low temperature were examined. It was found that the mechanical properties are strongly related to the defects formed in the welding process.

  9. Synthesis and Characterization of Quaternary Complexes Ln ( CH2 ClCO0 ) 2 ( NO3 ) ( phen)

    Institute of Scientific and Technical Information of China (English)

    咸春颖; 赵曙辉; 朱龙观; 谢学鹏

    2001-01-01

    Many trinary lanthanide complexes have been studied. However, few mixed anion complexes with bidentate heterocyclic amines were synthesized. We synthesized mixed anion complexes Ln ( CHi CICO0 )2 (NO3) (phen) which was determined by elemental analyses. The IR spectra analyses indicate that NO3 ,CH2 C1CO0- and phen are coordinated with Ln. The molar conductances of the complexes at 10-3 mol. L-1 were founded to be between 32.4 and 35.8 S. cma@mol- 1 , suggesting the nonelectrolytes in N Dimethylformamide. And we determined the fluorescent spectra Eu(CH2C1COO)2(NO3) ( phen ) and ESR spectra of Gd( CH2 ClC00 )2 ( NOs ) ( phen ) .

  10. The Earth's early evolution.

    Science.gov (United States)

    Bowring, S A; Housh, T

    1995-09-15

    The Archean crust contains direct geochemical information of the Earth's early planetary differentiation. A major outstanding question in the Earth sciences is whether the volume of continental crust today represents nearly all that formed over Earth's history or whether its rates of creation and destruction have been approximately balanced since the Archean. Analysis of neodymium isotopic data from the oldest remnants of Archean crust suggests that crustal recycling is important and that preserved continental crust comprises fragments of crust that escaped recycling. Furthermore, the data suggest that the isotopic evolution of Earth's mantle reflects progressive eradication of primordial heterogeneities related to early differentiation.

  11. Near Earth Objects

    DEFF Research Database (Denmark)

    Wolff, Stefan

    2006-01-01

    , Near Earth Objects: Asteroids and comets following paths that bring them near the Earth. NEOs have collided with the Earth since its formation, some causing local devastation, some causing global climate changes, yet the threat from a collision with a near Earth object has only recently been recognised...... of starlight by the Sun, and therefore directly observe the structure of space-time. This thesis explores several aspects of the observation of NEOs with Gaia, emphasising detection of NEOs and the quality of orbits computed from Gaia observations. The main contribution is the work on motion detection...

  12. Aqueous Binary Lanthanide(III) Nitrate Ln(NO3)3 Electrolytes Revisited: Extended Pitzer and Bromley Treatments

    Energy Technology Data Exchange (ETDEWEB)

    Chatterjee, Sayandev; Campbell, Emily L.; Neiner, Doinita; Pence, Natasha; Robinson, Troy; Levitskaia, Tatiana G.

    2015-09-11

    To date, only limited thermodynamic models describing activity coefficients of the aqueous solutions of lanthanide ions are available. This work expands the existing experimental osmotic coefficient data obtained by classical isopiestic technique for the aqueous binary trivalent lanthanide nitrate Ln(NO3)3 solutions using a combination of water activity and vapor pressure osmometry measurements. The combined osmotic coefficient database for each aqueous lanthanide nitrate at 25°C, consisting of literature available data as well as data obtained in this work, was used to test the validity of Pitzer and Bromley thermodynamic models for the accurate prediction of mean molal activity coefficients of the Ln(NO3)3 solutions in wide concentration ranges. The new and improved Pitzer and Bromley parameters were calculated. It was established that the Ln(NO3)3 activity coefficients in the solutions with ionic strength up to 12 mol kg-1 can be estimated by both Pitzer and single-parameter Bromley models, even though the latter provides for more accurate prediction, particularly in the lower ionic strength regime (up to 6 mol kg-1). On the other hand for the concentrated solutions, the extended three-parameter Bromley model can be employed to predict the Ln(NO3)3 activity coefficients with remarkable accuracy. The accuracy of the extended Bromley model in predicting the activity coefficients was greater than ~95% and ~90% for all solutions with the ionic strength up to 12 mol kg-1 and and 20 mol kg-1, respectively. This is the first time that the activity coefficients for concentrated lanthanide solutions have been predicted with such a remarkable accuracy.

  13. Design Guidelines for Collaboration and Participation with Examples from the LN4LD (Learning Network for Learning Design)

    OpenAIRE

    2007-01-01

    Burgos, D., Hummel, H. G. K., Tattersall, C., Brouns, F., & Koper, R. (2009). Design Guidelines for Collaboration and Participation with Examples from the LN4LD (Learning Network for Learning Design). In L. Lockyer, S. Bennett, S. Agostinho & B. Harper (Eds.), Handbook of Research on Learning Design and Learning Objects: Issues, Applications and Technologies (Vol. 1, pp 373-389). Hershey, New York: Information Science Reference, IGI Global.

  14. Orthopositronium lifetime at O({alpha}) and O({alpha}{sup 3} ln {alpha}) in closed form

    Energy Technology Data Exchange (ETDEWEB)

    Kniehl, B.A.; Kotikov, A.V.; Veretin, O.L. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

    2009-09-15

    Recently, the O({alpha}) and O({alpha}{sup 3} ln{alpha}) radiative corrections to the orthopositronium lifetime have been presented in closed analytical form, in terms of basic irrational numbers that can be evaluated numerically to arbitrary precision [Phys. Rev. Lett. 101, 193401 (2008)]. Here, we present the details of this calculation and reveal the nature of these new constants. We also list explicit transformation formulas for generalized polylogarithms of weight four, which may be useful for other applications. (orig.)

  15. Post-Synthetic Shaping of Porosity and Crystal Structure of Ln-Bipy-MOFs by Thermal Treatment

    Directory of Open Access Journals (Sweden)

    Philipp R. Matthes

    2015-07-01

    Full Text Available The reaction of anhydrous lanthanide chlorides together with 4,4′-bipyridine yields the MOFs 2∞[Ln2Cl6(bipy3]·2bipy, with Ln = Pr − Yb, bipy = 4,4′-bipyridine, and 3∞[La2Cl6(bipy5]·4bipy. Post-synthetic thermal treatment in combination with different vacuum conditions was successfully used to shape the porosity of the MOFs. In addition to the MOFs microporosity, a tuneable mesoporosity can be implemented depending on the treatment conditions as a surface morphological modification. Furthermore, thermal treatment without vacuum results in several identifiable crystalline high-temperature phases. Instead of collapse of the frameworks upon heating, further aggregation under release of bipy is observed. 3∞[LaCl3(bipy] and 2∞[Ln3Cl9(bipy3], with Ln = La, Pr, Sm, and 1∞[Ho2Cl6(bipy2] were identified and characterized, which can also exhibit luminescence. Besides being released upon heating, the linker 4,4′-bipyridine can undergo activation of C-C bonding in ortho-position leading to the in-situ formation of 4,4′:2′,2′′:4′′,4′′′-quaterpyridine (qtpy. qtpy can thereby function as linker itself, as shown for the formation of the network 2∞[Gd2Cl6(qtpy2(bipy2]·bipy. Altogether, the manuscript elaborates the influence of thermal treatment beyond the usual activation procedures reported for MOFs.

  16. Capturing near-Earth asteroids around Earth

    Science.gov (United States)

    Hasnain, Zaki; Lamb, Christopher A.; Ross, Shane D.

    2012-12-01

    The list of detected near-Earth asteroids (NEAs) is constantly growing. NEAs are likely targets for resources to support space industrialization, as they may be the least expensive source of certain needed raw materials. The limited supply of precious metals and semiconducting elements on Earth may be supplemented or even replaced by the reserves floating in the form of asteroids around the solar system. Precious metals make up a significant fraction NEAs by mass, and even one metallic asteroid of ˜1km size and fair enrichment in platinum-group metals would contain twice the tonnage of such metals already harvested on Earth. There are ˜1000 NEAs with a diameter of greater than 1 km. Capturing these asteroids around the Earth would expand the mining industry into an entirely new dimension. Having such resources within easy reach in Earth's orbit could provide an off-world environmentally friendly remedy for impending terrestrial shortages, especially given the need for raw materials in developing nations. In this paper, we develop and implement a conceptually simple algorithm to determine trajectory characteristics necessary to move NEAs into capture orbits around the Earth. Altered trajectories of asteroids are calculated using an ephemeris model. Only asteroids of eccentricity less than 0.1 have been studied and the model is restricted to the ecliptic plane for simplicity. We constrain the time of retrieval to be 10 years or less, based on considerations of the time to return on investment. For the heliocentric phase, constant acceleration is assumed. The acceleration required for transporting these asteroids from their undisturbed orbits to the sphere of influence of the Earth is the primary output, along with the impulse or acceleration necessary to effect capture to a bound orbit once the Earth's sphere of influence is reached. The initial guess for the constant acceleration is provided by a new estimation method, similar in spirit to Edelbaum's. Based on the

  17. Rare-earth dialkyl and dihydride complexes bearing monoanionic ancillary ligands

    Institute of Scientific and Technical Information of China (English)

    CHENG JianHua; HOU ZhaoMin

    2011-01-01

    Rare-earth elements,including scandium,yttrium,and the lanthanides (La-Lu),possess unique chemical and physical properties,and constitute one of the last frontiers in the periodic table.Rare-earth elements are vital for many high-tech industry products such as smartphones and electric cars.However,the fundamental chemistry of the rareearth elements has been explored to a far less extent.The first organo rare-earth complexes Cp3Ln (1,Figure 1),which bear three cyclopentadienyl (Cp) ligands,were reported in the early 1950s [1],but these complexes did not receive much attention because of the lack of significant reactivity.In the early 1980s,the alkyl and hydride complexes supported by two cyclopentadienyl ligands (such as 2in Figure 1) were reported [2].

  18. 2-D and 3-D phosphotungstate-based TM-Ln heterometallic derivatives constructed from dimeric [Ln({alpha}-PW{sub 11}O{sub 39}){sub 2}]{sup 11-} fragments and copper-organic complex linkers

    Energy Technology Data Exchange (ETDEWEB)

    Shang, Sensen [Institute of Molecular and Crystal Engineering, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Zhao, Junwei, E-mail: zhaojunwei@henu.edu.cn [Institute of Molecular and Crystal Engineering, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Chen, Lijuan [Institute of Molecular and Crystal Engineering, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Basic Experiment Teaching Center, Henan University, Kaifeng, Henan 475004 (China); Li, Yuye; Zhang, Jingli; Li, Yanzhou [Institute of Molecular and Crystal Engineering, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Niu, Jingyang, E-mail: jyniu@henu.edu.cn [Institute of Molecular and Crystal Engineering, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China)

    2012-12-15

    Three organic-inorganic hybrid TM-Ln heterometallic phosphotungstates [Cu(dap){sub 2}(H{sub 2}O)][Cu(dap){sub 2}]{sub 3.5}[La({alpha}-HPW{sub 11}O{sub 39}){sub 2}]{center_dot}6H{sub 2}O (1) [Cu(dap){sub 2}(H{sub 2}O)]{sub 0.5}[Cu(dap){sub 2}]{sub 4}[Nd({alpha}-HPW{sub 11}O{sub 39}){sub 2}]{center_dot}4H{sub 2}O (2) and [Cu(dap){sub 2}(H{sub 2}O)]{sub 2}[Cu(dap){sub 2}]{sub 3.5}[Eu({alpha}-PW{sub 11}O{sub 39}){sub 2}]{center_dot}6H{sub 2}O (3) (dap=1,2-diaminopropane) have been hydrothermally synthesized and structurally characterized by elemental analyses, IR spectra, optical diffuse reflectance spectra, powder X-ray diffraction (PXRD), thermogravimetric (TG) analyses and single-crystal X-ray diffraction. Their common features are that 1-3 all consist of asymmetric sandwich-type subunits [Ln({alpha}-PW{sub 11}O{sub 39}){sub 2}]{sup 11-} and [Cu(dap){sub 2}]{sup 2+} bridges. Both 1 and 2 display the 2-D (4,4)-topological sheets whereas 3 exhibits the 3-D 5-connected (4{sup 6}{center_dot}6{sup 4}) topological framework. The magnetic properties of 2 and 3 and the luminescence performance of 3 have been measured. - Graphical Abstract: Three TM-Ln heterometallic phosphotungstates 1-3 have been synthesized and characterized by elemental analyses, IR spectra, optical diffuse reflectance spectra, X-ray diffraction, thermogravimetric analyses magnetic susceptibility and luminescent properties. Highlights: Black-Right-Pointing-Pointer Cu{sup II}-Ln{sup III} heterometallic polyoxometalates. Black-Right-Pointing-Pointer 2-D and 3-D organic-inorganic hybrid phosphotungstates. Black-Right-Pointing-Pointer 2-D and 3-D structures consisting of Cu{sup II}-Ln{sup III} heterometals.

  19. Fundamentální analýza numerických dat pro automatický trading

    OpenAIRE

    Huf, Petr

    2016-01-01

    Tato práce se zabývá využitím fundamentální analýzy v automatickém obchodování. Technická analýza využívá k predikci ceny hlavně její historické hodnoty a indikátory z této ceny odvozené. Fundamentální analýza naopak využívá informace z různých zdrojů k predikci cenového signálu, přičemž v této práci byly zkoumány pouze kvantitativní zdroje dat. Konkrétně se jedná o počasí, Forex, Google Trends, WikiTrends, historické ceny různých futures a souhrnná fundamentální data (porodnost, migrace, \\do...

  20. Zpracování digitálních signálů z interferometru

    OpenAIRE

    2011-01-01

    Bakalářská práce se zabývá zpracováním digitálního signálu formátu S/PDIF z interferometru Polytec OFV-5000, pomocí měřicí aplikace vytvořené ve vývojovém prostředí LabVIEW. V této práci je popsána teorie laserového měření vibrací a kódování digitálního signálu S/PDIF. Dále je představen systém pro měření vibrací Polytec a systém pro sběr dat National Instruments. Následuje popis vytvořené měřicí aplikace, rozdělen na tři části: dekódování signálu S/PDIF, sběr a zobrazení digitálních dat a sb...

  1. Photoluminescence properties of lanthanide-organic frameworks (LnOFs) with thiophene-2,5-dicarboxylate and acetate

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jing; Wei, Qing; Xie, Gang; Chen, Sanping [Key Lab. of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest Univ., Xi' an, Shaanxi (China); Zhang, Sheng [Key Lab. of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest Univ., Xi' an, Shaanxi (China); College of Chemistry and Chemical Engineering, Baoji Univ. of Arts and Science, Baoji, Shaanxi (China)

    2017-07-17

    S-heterocyclic dicarboxylic acid, thiophene-2,5-dicarboxylic acid (H{sub 2}TDC), was employed to construct a series of lanthanide-organic frameworks (LnOFs) with coligand acetate, formulated as [Ln(TDC)(OAc)(H{sub 2}O)]{sub n} [Ln = Eu (1), Tb (2), Gd (3), Dy (4), Sm (5)] under hydrothermal conditions. Structure analysis reveals that 1-5 have dinuclear 3D metal organic frameworks (MOFs), in which TDC{sup 2-} and OAc{sup -} display (κ{sup 1}-κ{sup 1})-(κ{sup 1}-κ{sup 1})-μ{sub 4} and (κ{sup 2}-κ{sup 1})-μ{sub 2} coordination fashions, respectively. The dehydrated products of all compounds show high thermal stability above 410 C. As for 1, 2, 4, and 5, the photoluminescence analyses exhibit characteristic luminescence emission bands of the corresponding lanthanide ions in the visible region. In particular, compound 2 displays bright green luminescence in the solid state with {sup 5}D{sub 4} lifetime of 0.510 ms and relative high overall quantum yield of 16 %, based on an ideal energy gap between the lowest triplet state energy level of H{sub 2}TDC ligand and the {sup 5}D{sub 4} state energy level of Tb{sup 3+}. The energy transfer mechanisms in compounds 1 and 2 were also discussed. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. A Conceptual Framework for the Electronic Performance Support Systems within IBM Lotus Notes 6 (LN6 Example

    Directory of Open Access Journals (Sweden)

    Servet BAYRAM

    2005-10-01

    Full Text Available A Conceptual Framework for the Electronic PerformanceSupport Systems within IBM Lotus Notes 6 (LN6 Example Assoc. Prof. Dr. Servet BAYRAM Computer Education & Instructional Technologies Marmara University, TURKEYsbayram@marmara.edu.tr ABSTRACT The concept of Electronic Performance Support Systems (EPSS is containing multimedia or computer based instruction components that improves human performance by providing process simplification, performance information and decision support system. EPSS has become a hot topic for organizational development, human resources, performance technology, training, and educational development professionals. A conceptual framework of EPSS is constructed under five interrelated and interdependent domains for educational implications. The domains of the framework are online collaboration, cost-effectiveness, motivation, service management, and performance empowering. IBM Lotus Notes 6 (LN6 is used as an example application tool to illustrate the power of this framework. The framework describes a set of relevant events based upon deductive analyses for improving our understanding of the EPSS and its implications on education and training. The article is also pointed out that there are some similarities between the EPSS’ and the LN6’s specific features within this conceptual framework. It can provide some guidelines and benefits to researchers, educators, and designers as well.

  3. Synthesis and crystal and molecular structure of three heterometallic polymeric compounds (Ln{sub 2}[LnGe{sub 6}(μ-Oedph){sub 6}(μ-O){sub 3}(μ-OH){sub 3}(H{sub 2}O){sub 4}] · xH{sub 2}O){sub n} [Ln = Nd, x ∼ 26 (I); Er, x ∼ 24 (II); Tm, x ∼ 20 (III); H{sub 4}Oedph = 1-hydroxyethylidenediphosphonic acid

    Energy Technology Data Exchange (ETDEWEB)

    Sergienko, V. S., E-mail: sergienko@igic.ras.ru [Russian Academy of Sciences, Kurnakov Institute of General and Inorganic Chemistry (Russian Federation); Martsinko, E. E. [Mechnikov Odessa National University (Ukraine); Ilyukhin, A. B. [Russian Academy of Sciences, Kurnakov Institute of General and Inorganic Chemistry (Russian Federation); Seifullina, I. I. [Mechnikov Odessa National University (Ukraine)

    2015-03-15

    The synthesis and X-ray diffraction study of three heterometallic compounds of general formula (Ln{sub 2}[LnGe{sub 6}(μ-Oedph){sub 6}(μ-O){sub 3}(μ-OH){sub 3}(H{sub 2}O){sub 4}] · xH{sub 2}O){sub n} [Ln = Nd, x ∼ 26 (I); Er, x ∼ 24 (II); Tm, x ∼20 (III); H{sub 4}Oedph = 1-hydroxyethylidenediphosphonic acid] are performed. The basis element of structures I–III is a hexanuclear complex anion [Ge(μ-Oedph)(μ-O){sub 0.5}(μ-OH){sub 0.5}]{sub 6}{sup 9−}, in which bridging hydroxo and oxo ligands are statistically disordered with equally probability. Hexameric units are connected by Ln1(H{sub 2}O){sub 4} fragments into a framework whose channels are completely populated by disordered lanthanide atoms and water molecules.

  4. Structure of Ln[sub 2](PO[sub 3]H)[sub 3]. H[sub 2]O (Ln=Pr, Nd). Structure de Ln[sub 2](PO[sub 3]H)[sub 3]. H[sub 2]O (Ln=Pr, Nd)

    Energy Technology Data Exchange (ETDEWEB)

    Foulon, J.D.; Durand, J.; Cot, L. (Lab. de Physicochimie des Materiaux, Ecole Nationale Superieure de Chimie, 34 - Montpellier (France)); Tijani, N.; Rafiq, M. (Lab. de Chimie Minerale Appliquee, Faculte des Sciences, Fes (Morocco))

    1993-01-15

    Dipraseodymium triphosphite monohydrate, Pr[sub 2](PO[sub 3]H)[sub 3].H[sub 2]O, M[sub r]=539.8, monoclinic, P2[sub 1]/n, a=9.620(2), b=8.005(1), c=13.119(2) A, [beta]=108.98(1)deg, V=955.4(3) A[sup 3], Z=4, D[sub m]=3.72(1), D[sub x]=3.754 Mg m[sup -3], [lambda](Mo K[alpha])=0.71073 A, [mu]=10.68 mm[sup -1], F(000)=992, T=293 K, R=0.025 for 1947 independent reflections. Dineodymium triphosphite monohydrate, Nd[sub 2](PO[sub 3]H)[sub 3].H[sub 2]O, M[sub r]=546.4, monoclinic, P2[sub 1]/n, a=9.581(2), b=7.980(2), c=13.056(3) A, [beta]=108.95(1)deg, V=944.2(4) A[sup 3], Z=4, D[sub m]=3.81(1), D[sub x]=3.845 Mg m[sup -3], [lambda](Mo K[alpha])=0.71073 A, [mu]=11.51 mm[sup -1], F(000)=1000, T=293 K, R=0.0305 for 1992 independent reflections. The structure contains three independent phosphite anions. Both Ln[sup 3+] are eight-coordinated: One by eight O atoms of six different phosphite anions, but the other by only seven O atoms of six different phosphite anions and one water O atom. (orig.).

  5. Metabolic fate of L-(N-13) glutamate in normal isolated myocardium

    Energy Technology Data Exchange (ETDEWEB)

    Keen, R.E.; Krivokapich, J.; Barrio, J.R.; Douglas, A.; Wittmer, S.; Shine, K.; Phelps, M.E.

    1984-01-01

    In the present work nitrogen flux of an amino acid in myocardium is followed via arterial bolus injection of non-carrier added L-(N-13)glutamate (N-13 GLU) into the isolated rabbit septa. Incorporation of nitrogen-13 into (N-13)aspartate (N-13 ASP)(16%) and (N-13)alanine (N-13 ALA)(14%) predominates over (N-13)glutamine (N-13 GLN) (3.2%) as determined by reversed phase HPLC in normal septa 6 min after bolus injection. No N-13 ammonia or N-13 urea is detected. Introduction of the transaminase inhibitor aminooxyacetate (AOA, 2 nM) into perfusate completely blocked transaminase reaction and increased N-13 GLN (7.3%) and free N-13 ammonia (4.0%), probably resulting from glutamate dehydrogenase reaction. Inclusion of 2mM pyruvate in the perfusate resulted in 3 fold increase in N-13 ALA (44%), slight increase in N-13 GLN (5.0%) and significant decrease in N-13 ASP. Addition of 2mM AOA in the presence of pyruvate blocked production of N-13 ASP and N-13 ALA, and increased N-13 GLN slightly (6.0%). All studies had similar residual fractions (50%) except AOA treated septa (23%) indicating decreased metabolic trapping of the N-13 label. In conclusion, nitrogen-13 distribution in tissue is primarily governed by glutamate interaction with transaminases. Although the Michaelis constants of glutamate for GOT (Km = 4 nM, pig heart), GPT (Km = 8.1 mM, beef heart) and glutamine synthetase (Km = 2.5 mM, ovine brain) are similar, the transaminases play a predominant role because of their great abundance in myocardial tissue.

  6. Introducing Earth's Orbital Eccentricity

    Science.gov (United States)

    Oostra, Benjamin

    2015-01-01

    Most students know that planetary orbits, including Earth's, are elliptical; that is Kepler's first law, and it is found in many science textbooks. But quite a few are mistaken about the details, thinking that the orbit is very eccentric, or that this effect is somehow responsible for the seasons. In fact, the Earth's orbital eccentricity is…

  7. The Earth's Core.

    Science.gov (United States)

    Jeanloz, Raymond

    1983-01-01

    The nature of the earth's core is described. Indirect evidence (such as that determined from seismological data) indicates that it is an iron alloy, solid toward its center but otherwise liquid. Evidence also suggests that it is the turbulent flow of the liquid that generates the earth's magnetic field. (JN)

  8. Crystal structure and dielectric properties of Ca(0.85)Nd(0.1)TiO(3) - LnAlO(3) ceramics.

    Science.gov (United States)

    Eung, S; Dong, H; Yang, Jun-Mo; Hyung, S; Nur, I; Ohsato, Hitoshi

    2008-05-01

    The microwave dielectric properties of Ca(0.85)Nd(0.1)TiO(3) - LnAlO(3) (Ln = Sm, Gd, Dy, Er) ceramics are investigated in this paper. The structural characteristics of the specimens were evaluated by Rietveld refinement of Xray diffraction (XRD) patterns and high-resolution transmission electron microscopy (HRTEM). Solid solution limits were dependent on the ionic radius of Ln(3+) ions. With the decrease of the ionic radius of the Ln(3+) ions, the thermal stability of the resonant frequency decreases. This can be attributed to the increased level of oxygen octahedral distortion caused by the increase in the B-site bond valence in the ABO(3) perovskite structure. The dielectric constant (K) and the quality factor (Qf) of the specimens were dependent on the polarizability and grain size, respectively.

  9. Genetic and proteomic characterization of rpoB mutations and their effect on nematicidal activity in Photorhabdus luminescens LN2.

    Directory of Open Access Journals (Sweden)

    Xuehong Qiu

    Full Text Available Rifampin resistant (Rif(R mutants of the insect pathogenic bacterium Photorhabdus luminescens LN2 from entomopathogenic nematode Heterorhabditis indica LN2 were genetically and proteomically characterized. The Rif(R mutants showed typical phase one characters of Photorhabdus bacteria, and insecticidal activity against Galleria mellonella larvae, but surprisingly influenced their nematicidal activity against axenic infective juveniles (IJs of H. bacteriophora H06, an incompatible nematode host. 13 out of 34 Rif(R mutants lost their nematicidal activity against H06 IJs but supported the reproduction of H06 nematodes. 7 nematicidal-producing and 7 non-nematicidal-producing Rif(R mutants were respectively selected for rpoB sequence analysis. rpoB mutations were found in all 14 Rif(R mutants. The rpoB (P564L mutation was found in all 7 mutants which produced nematicidal activity against H06 nematodes, but not in the mutants which supported H06 nematode production. Allelic exchange assays confirmed that the Rif-resistance and the impact on nematicidal activity of LN2 bacteria were conferred by rpoB mutation(s. The non-nematicidal-producing Rif(R mutant was unable to colonize in the intestines of H06 IJs, but able to colonize in the intestines of its indigenous LN2 IJs. Proteomic analysis revealed different protein expression between wild-type strain and Rif(R mutants, or between nematicidal-producing and non nematicidal-producing mutants. At least 7 putative proteins including DsbA, HlpA, RhlE, RplC, NamB (a protein from T3SS, and 2 hypothetical proteins (similar to unknown protein YgdH and YggE of Escherichia coli respectively were probably involved in the nematicidal activity of LN2 bacteria against H06 nematodes. This hypothesis was further confirmed by creating insertion-deletion mutants of three selected corresponding genes (the downregulated rhlE and namB, and upregulated dsbA. These results indicate that the rpoB mutations greatly influence the

  10. Solid Earth: Introduction

    Science.gov (United States)

    Rummel, R.

    1991-10-01

    The principles of the solid Earth program are introduced. When considering the study of solid Earth from space, satellites are used as beacons, inertial references, free fall probes and carrying platforms. The phenomenon measured by these satellites and the processes which can be studied as a result of these measurements are tabulated. The NASA solid Earth program focusses on research into surface kinematics, Earth rotation, land, ice, and ocean monitoring. The ESA solid Earth program identifies as its priority the Aristoteles mission for determining the gravity and magnetic field globally, with high spatial resolution and high accuracy. The Aristoteles mission characteristics and goals are listed. The benefits of the improved gravity information that will be provided by this mission are highlighted. This information will help in the following research: geodesy, orbit mechanics, geodynamics, oceanography, climate sea level, and the atmosphere.

  11. Synthesis and characterization of N-aryloxo-functiona-lized B-ketoiminate rare-earth complexes and their catalytic activity for the polymerization of ε-caprolactone

    Institute of Scientific and Technical Information of China (English)

    HAN XiangZong; WU LiangLiang; YAO YingMing; ZHANG Yong; SHEN Qi

    2009-01-01

    The synthesis and characterization of dimeric rare-earth amides stabilized by a dianionic N-aryloxo functionalized β-ketoiminate Iigand are described. Reactions of 4-(2-hydroxy-5-methyl-phenyl) im-ino-2-pentanone (LH_2) with Ln[N(SiMe_3)_2]_3(μ-Cl)Li(THF)_3 in a 1:1 molar ratio in THF gave the dimeric rare-earth amido complexes [LLn{N(SiMe_3)_2}(THF)]_2 [Ln= Nd (1), Sm (2), Yb (3), Y (4)]. These complexes were well characterized, and the definitive molecular structures of complexes 3 and 4 were determined. It was found that complexes 1-4 can initiate the ring-opening polymerization of ε-caprolactone, and the ionic radii of the central metals have significant effect on the catalytic activity.

  12. ln vitro propagation of Hylocereus purpusii Britton & Rose, a mexican species in danger of extinction

    OpenAIRE

    Manuel de Feria; Daniel Rojas; Maité Chávez; Mireya Reyna; Elisa Quiala; Juan Solís; Florentina Zurita

    2012-01-01

    The purpose ofthis workwasto evalúate different conditions and culture parametersforthein vitro establishment and multiplicaron of Hylocereus purpusii. Seeds were used as plant material and a workflowwas developed as an alternative forthe propagation and recovery ofthis species in danger of extinction. ln the establishment phase, the best result was obtained in the treatment with 1% NaOCI for 15 minutes achieving a 90% of germinated seeds and a final 77.7% of in vitro established plants. ln t...

  13. Exploring the critical dependence of adsorption of various dyes on the degradation rate using Ln{sup 3+}-TiO{sub 2} surface under UV/solar light

    Energy Technology Data Exchange (ETDEWEB)

    Devi, L. Gomathi, E-mail: gomatidevi_naik@yahoo.co.in [Department of Post Graduate Studies in Chemistry, Central College City Campus, Dr. Ambedkar Street, Bangalore University, Bangalore 560001 (India); Kumar, S. Girish [Department of Post Graduate Studies in Chemistry, Central College City Campus, Dr. Ambedkar Street, Bangalore University, Bangalore 560001 (India)

    2012-11-15

    Graphical abstract: The surface reactive acidic sites enhances on doping with rare earth ions which facilitates efficient adsorption of the dye molecules on the catalyst surface. In addition, the nature of the dopant, its concentration and electronic configuration additionally contributes to the overall efficiency. Highlights: Black-Right-Pointing-Pointer The degradation of structurally different anionic dyes under different pH conditions is reported. Black-Right-Pointing-Pointer Pre adsorption of pollutant on catalyst surface is vital for efficient photocatalysis. Black-Right-Pointing-Pointer Adsorption of dye on the catalyst surface depends on the substituent's attached to it. Black-Right-Pointing-Pointer The dopant with half filled electronic configuration served as shallow traps for charge carriers. - Abstract: The degradation of structurally different anionic dyes like Alizarin Red S (ARS) Amaranth (AR), Brilliant Yellow (BY), Congo Red (CR), Fast Red (FR), Methyl Orange (MO), and Methyl Red (MR) were carried out using Ln{sup 3+} (Ln{sup 3+} = La{sup 3+}, Ce{sup 3+} and Gd{sup 3+}) doped TiO{sub 2} at different pH conditions under UV/solar light. All the anionic dyes underwent rapid degradation at acidic pH, while resisted at alkaline conditions due to the adsorptive tendency of these dyes on the catalyst surface at different pH conditions. Gd{sup 3+} (0.15 mol%)-TiO{sub 2} exhibited better activity compared to other photocatalyst ascribed to half filled electronic configuration of Gd{sup 3+} ions. It is proposed that Ln{sup 3+} serves only as charge carrier traps under UV light, while it also act as visible light sensitizers under solar light. Irrespective of the catalyst and excitation source, the dye degradation followed the order: AR > FR > MO > MR > ARS > BY > CR. The results suggest that pre-adsorption of the pollutant is vital for efficient photocatalysis which is dependent on the nature of the substituent's group attached to the dye molecule.

  14. Earth as art three

    Science.gov (United States)

    ,

    2010-01-01

    For most of us, deserts, mountains, river valleys, coastlines even dry lakebeds are relatively familiar features of the Earth's terrestrial environment. For earth scientists, they are the focus of considerable scientific research. Viewed from a unique and unconventional perspective, Earth's geographic attributes can also be a surprising source of awe-inspiring art. That unique perspective is space. The artists for the Earth as Art Three exhibit are the Landsat 5 and Landsat 7 satellites, which orbit approximately 705 kilometers (438 miles) above the Earth's surface. While studying the images these satellites beam down daily, researchers are often struck by the sheer beauty of the scenes. Such images inspire the imagination and go beyond scientific value to remind us how stunning, intricate, and simply amazing our planet's features can be. Instead of paint, the medium for these works of art is light. But Landsat satellite sensors don't see light as human eyes do; instead, they see radiant energy reflected from Earth's surface in certain wavelengths, or bands, of red, green, blue, and infrared light. When these different bands are combined into a single image, remarkable patterns, colors, and shapes emerge. The Earth as Art Three exhibit provides fresh and inspiring glimpses of different parts of our planet's complex surface. The images in this collection were chosen solely based on their aesthetic appeal. Many of the images have been manipulated to enhance color variations or details. They are not intended for scientific interpretation only for your viewing pleasure. Enjoy!

  15. Sun-Earth Days

    Science.gov (United States)

    Thieman, J.; Ng, C.; Lewis, E.; Cline, T.

    2010-08-01

    Sun-Earth Day is a well-coordinated series of programs, resources and events under a unique yearly theme highlighting the fundamentals of heliophysics research and missions. A menu of activities, conducted throughout the year, inspire and educate participants. Sun-Earth Day itself can vary in date, but usually is identified by a celebration on or near the spring equinox. Through the Sun-Earth Day framework we have been able to offer a series of coordinated events that promote and highlight the Sun, its connection to Earth and the other planets. Sun-Earth Day events are hosted by educators, museums, amateur astronomers and scientists and occur at schools, community groups, parks, planetaria and science centers around the globe. Sun-Earth Day raises the awareness and knowledge of formal and informal education audiences concerning space weather and heliophysics. By building on the success of Sun-Earth Day yearly celebrations, we seek to affect people of all backgrounds and ages with the wonders of heliophysics science, discovery, and exploration in ways that are both tangible and meaningful to their lives.

  16. Accretion of the Earth.

    Science.gov (United States)

    Canup, Robin M

    2008-11-28

    The origin of the Earth and its Moon has been the focus of an enormous body of research. In this paper I review some of the current models of terrestrial planet accretion, and discuss assumptions common to most works that may require re-examination. Density-wave interactions between growing planets and the gas nebula may help to explain the current near-circular orbits of the Earth and Venus, and may result in large-scale radial migration of proto-planetary embryos. Migration would weaken the link between the present locations of the planets and the original provenance of the material that formed them. Fragmentation can potentially lead to faster accretion and could also damp final planet orbital eccentricities. The Moon-forming impact is believed to be the final major event in the Earth's accretion. Successful simulations of lunar-forming impacts involve a differentiated impactor containing between 0.1 and 0.2 Earth masses, an impact angle near 45 degrees and an impact speed within 10 per cent of the Earth's escape velocity. All successful impacts-with or without pre-impact rotation-imply that the Moon formed primarily from material originating from the impactor rather than from the proto-Earth. This must ultimately be reconciled with compositional similarities between the Earth and the Moon.

  17. Electronic and magnetic properties of superconducting LnO1-x F x BiS2 (Ln  =  La, Ce, Pr, and Nd) from first principles

    Science.gov (United States)

    Morice, Corentin; Artacho, Emilio; Dutton, Siân E.; Kim, Hyeong-Jin; Saxena, Siddharth S.

    2016-09-01

    A density functional theory study of the BiS2 superconductors containing rare-earths: LnO1-x F x BiS2 (Ln  =  La, Ce, Pr, and Nd) is presented. We find that CeO0.5F0.5BiS2 has competing ferromagnetic and weak antiferromagnetic tendencies, the first one corresponding to experimental results. We show that PrO0.5F0.5BiS2 has a strong tendency for magnetic order, which can be ferromagnetic or antiferromagnetic depending on subtle differences in 4f orbital occupations. We demonstrate that NdO0.5F0.5BiS2 has a stable magnetic ground state with weak tendency to order. Finally, we show that the change of rare earth does not affect the Fermi surface, and predict that CeOBiS2 should display a pressure induced phase transition to a metallic, if not superconducting, phase under pressure.

  18. Molecular catalysis of rare-earth elements

    Energy Technology Data Exchange (ETDEWEB)

    Roesky, Peter W. (ed.) [Karlsruhe Institute of Technology (KIT) (Germany). Inst. of Inorganic Chemistry

    2010-07-01

    reviewed in detail. For example, the use of molecular rare-earth metal complexes as Lewis acidic catalysts is not discussed in this book. The first two chapters review different catalytic conversions, namely the catalytic {sigma}-bond metathesis (Chapter by Reznichenko and Hultzsch) and the polymerization of 1,3-conjugated dienes (Chapter by Zhang et al.). Within these chapters, different catalytic systems and applications are discussed. The final two chapters are more concentrated on recent developments of catalysts synthesis; but of course catalytic aspects are also mentioned. Therefore, these two chapters are focused on homogeneous catalysis using lanthanide amidinates and guanidinates (Chapter by Edelmann) and the synthesis of rare-earth metal post-metallocene catalysts with chelating amido ligands (Chapter by Li et al.). The organometallic lanthanide catalysts of the first generation, which are the metallocene catalysts of the general composition [({eta}{sup 5}-C{sub 5}Me{sub 5}){sub 2}LnR] (R = CH(SiMe{sub 3}){sub 2}, N(SiMe{sub 3}){sub 2}, H), are mentioned in the first two chapters, but are not covered in a separate synthetic contribution because a number of excellent reviews on this topic have been published over the recent years. In summary, the present volume of Structure and Bonding shows the substantial activity carried out in recent years in the field of synthesis of inorganic and organometallic rare-earth metal compounds and their use as catalysts for a number of different transformations. The future holds great promise for the rapid growth of this field of chemistry and for new spectacular results. (orig.)

  19. Earth Science Informatics - Overview

    Science.gov (United States)

    Ramapriyan, H. K.

    2017-01-01

    Over the last 10-15 years, significant advances have been made in information management, there are an increasing number of individuals entering the field of information management as it applies to Geoscience and Remote Sensing data, and the field of informatics has come to its own. Informatics is the science and technology of applying computers and computational methods to the systematic analysis, management, interchange, and representation of science data, information, and knowledge. Informatics also includes the use of computers and computational methods to support decision making and applications. Earth Science Informatics (ESI, a.k.a. geoinformatics) is the application of informatics in the Earth science domain. ESI is a rapidly developing discipline integrating computer science, information science, and Earth science. Major national and international research and infrastructure projects in ESI have been carried out or are on-going. Notable among these are: the Global Earth Observation System of Systems (GEOSS), the European Commissions INSPIRE, the U.S. NSDI and Geospatial One-Stop, the NASA EOSDIS, and the NSF DataONE, EarthCube and Cyberinfrastructure for Geoinformatics. More than 18 departments and agencies in the U.S. federal government have been active in Earth science informatics. All major space agencies in the world, have been involved in ESI research and application activities. In the United States, the Federation of Earth Science Information Partners (ESIP), whose membership includes over 180 organizations (government, academic and commercial) dedicated to managing, delivering and applying Earth science data, has been working on many ESI topics since 1998. The Committee on Earth Observation Satellites (CEOS)s Working Group on Information Systems and Services (WGISS) has been actively coordinating the ESI activities among the space agencies.

  20. Earth Science Informatics - Overview

    Science.gov (United States)

    Ramapriyan, H. K.

    2017-01-01

    Over the last 10-15 years, significant advances have been made in information management, there are an increasing number of individuals entering the field of information management as it applies to Geoscience and Remote Sensing data, and the field of informatics has come to its own. Informatics is the science and technology of applying computers and computational methods to the systematic analysis, management, interchange, and representation of science data, information, and knowledge. Informatics also includes the use of computers and computational methods to support decision making and applications. Earth Science Informatics (ESI, a.k.a. geoinformatics) is the application of informatics in the Earth science domain. ESI is a rapidly developing discipline integrating computer science, information science, and Earth science. Major national and international research and infrastructure projects in ESI have been carried out or are on-going. Notable among these are: the Global Earth Observation System of Systems (GEOSS), the European Commissions INSPIRE, the U.S. NSDI and Geospatial One-Stop, the NASA EOSDIS, and the NSF DataONE, EarthCube and Cyberinfrastructure for Geoinformatics. More than 18 departments and agencies in the U.S. federal government have been active in Earth science informatics. All major space agencies in the world, have been involved in ESI research and application activities. In the United States, the Federation of Earth Science Information Partners (ESIP), whose membership includes over 180 organizations (government, academic and commercial) dedicated to managing, delivering and applying Earth science data, has been working on many ESI topics since 1998. The Committee on Earth Observation Satellites (CEOS)s Working Group on Information Systems and Services (WGISS) has been actively coordinating the ESI activities among the space agencies.The talk will present an overview of current efforts in ESI, the role members of IEEE GRSS play, and discuss

  1. Ln{sub 1-x}Sr{sub x}MnO{sub 3} (Ln=Pr, Nd, Sm and Gd) as the cathode material for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Sakaki, Y.; Takeda, Y.; Kato, A.; Imanishi, N.; Yamamoto, O. [Department of Chemistry, Faculty of Engineering, Mie University, Tsu 514-8507 (Japan); Hattori, M.; Iio, M.; Esaki, Y. [Electric Power R and D Center, Chubu Electric Power Company, Nagoya 459-8522 (Japan)

    1999-02-15

    The perovskite type manganite systems, Ln{sub 1-x}Sr{sub x}MnO{sub 3} (Ln=La, Pr, Nd, Sm, and Gd; 0{<=}x{<=}0.5) were studied as the electrode materials for solid oxide fuel cells (SOFC) from the view point of applications to the co-firing process of the electrolyte and electrode at a higher temperature. The reactivity tests with yttria-stabilized zirconia (YSZ) showed that the formation of the pyrochlore Ln{sub 2}Zr{sub 2}O{sub 7} was suppressed for the perovskites having smaller lanthanoids than La, especially for the Pr{sub 1-x}Sr{sub x}MnO{sub 3} and Nd{sub 1-x}Sr{sub x}MnO{sub 3} systems. No reaction product appeared between the Ln{sub 1-x}Sr{sub x}MnO{sub 3} perovskite and YSZ even at a high annealing temperature of 1400C when the lanthanoid elements were Pr, Nd and Sm and the Sr content was around 30% (x=0.3). The adjustment of the thermal expansion rate of Ln{sub 1-x}Sr{sub x}MnO{sub 3} to YSZ needed more Sr substitution with an increase of the atomic number of lanthanoids. The Sr contents, x, showing comparable values with 8m/o YSZ were around x=0.1-0.2 in La{sub 1-x}Sr{sub x}MnO{sub 3}, 0.3 in Pr{sub 1-x}Sr{sub x}MnO{sub 3} and Nd{sub 1-x}Sr{sub x}MnO{sub 3} and more than 0.4 in Sm{sub 1-x}Sr{sub x}MnO{sub 3} and Gd{sub 1-x}Sr{sub x}MnO{sub 3}. The electrical conductivity, which may strongly relate with the polarization of electrode reaction, showed about 200 S/cm at 1000C for all Ln{sub 0.7}Sr{sub 0.3}MnO{sub 3} systems. The polarization measurements as an air electrode showed no significant dependence on the kind of lanthanoid elements. From the viewpoint of the electrode activity, high electrical conductivity, low reactivity and good compatibility with YSZ, Pr{sub 0.7}Sr{sub 0.3}MnO{sub 3} and Nd{sub 0.7}Sr{sub 0.3}MnO{sub 3} are considered to be the most suitable electrode materials for the co-firing process

  2. Earth before life.

    Science.gov (United States)

    Marzban, Caren; Viswanathan, Raju; Yurtsever, Ulvi

    2014-01-09

    A recent study argued, based on data on functional genome size of major phyla, that there is evidence life may have originated significantly prior to the formation of the Earth. Here a more refined regression analysis is performed in which 1) measurement error is systematically taken into account, and 2) interval estimates (e.g., confidence or prediction intervals) are produced. It is shown that such models for which the interval estimate for the time origin of the genome includes the age of the Earth are consistent with observed data. The appearance of life after the formation of the Earth is consistent with the data set under examination.

  3. Synthesis and catalytic activity of Ln(III) complexes with an unsymmetrical Schiff base including multigroups

    Institute of Scientific and Technical Information of China (English)

    YAO; Kemin; (

    2003-01-01

    [1]Elder, R. C., Tridentate and unsymmetrical tetradentate Schiff base ligands from salicylaldehydes and dimeric nickel(II) complexes, Aust. J. Chem., 1978, 31:35-45.[2]Atkins, R., Brewer, G., Kokot, G. et al., Copper(II) and nickel(II) complexesof unsymmetrical tetradentate Schiff base ligand, Inorg. Chem., 1985, 24: 127-134.[3]Meng Qingjin, Wang Ruixue, Bu Xiuren et al., New Ni (II) complexes with mixedtrimeric double Schiff ligands, Chemical Journal of Chinese Universities (in Chinese), 1990, 10: 1126-1130.[4]Yao Kemin, Zhou Wen, Lu Gui et al., Synthesis, mechanism and NMR spectra of lanthanide complexes with a novel unsymmetrical Schiff base, Science in China, Series B, 1999, 42(2): 164-169.[5]Yao Kemin, Li Ning, Huang Qiaohong et al., Synthesis and catalytic activity of novel heteronuclear Ln(III)-Cu(II) complexes with noncyclic polyether-amino acid Schiff base, Science in China, Series B, 1999, 42 (1) : 54-81.[6]Li Ning, Yao Kemin, Lou Kaiyan, Synthesis of La(III), Y(III) complexes with polyglycol aldehyde-amino acid Schiff base and their high resolution solid state 13C NMR spectra, Science in China, Series B, 1999, 42(6): 599-604.[7]Lam Berf, J. B., Shurvell, H. F., Verbet, L. et al., Organic Structural Analysis, New York: Macmillan Publishing Co. Inc., 1975, 234-250.[8]Yao Kemin, Cai Lezhen, Shen Liangfang et al., Synthesis and characterization of lanthanide perchlorates with noncyclic polyethylene glycols and their 13C-NMRspectra, Polyhedron, 1992,11(7): 2245-2251.[9]Dewar, M. J. S., Zoebisch, E. G., Healy, E. F., AM1: A new general purpose quantum mechanical molecular model, J. Amer. Chem. Soc., 1985, 107: 3902-3909.[10]Feifer, P., Avnjr, D., Chemistry in noninteger dimensions between two and three, I. Fractal theory of heterogeneous surfaces, J. Chem. Phys., 1983, 79(7): 3558-3565.[11]Yang Haifeng, Wang Hui, Duan Jinxia et al., Ab initio research of organic ligand Schiff base 4-[(2-hydroxyphenyl) imine]-2

  4. 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

  5. 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.

  6. Visible light emitting Ln{sup 3+} ion (Ln=Sm, Eu and Dy) as a structural probe: A case study with SrZrO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Santosh K., E-mail: santufrnd@gmail.com [Radiochemistry Division, Bhabha Atomic Research Centre (India); Yadav, A.K.; Bhattacharya, D.; Jha, S.N. [Atomic and Molecular Physics Division, Bhabha Atomic Research Centre Trombay, Mumbai 400085 (India); Natarajan, V. [Radiochemistry Division, Bhabha Atomic Research Centre (India)

    2015-08-15

    Undoped and various rare earth ion doped SrZrO{sub 3} (SZO) perovskite based phosphors have been synthesized using the gel-combustion technique employing citric acid as a fuel. The phase purity of the sample is confirmed by the X-ray diffraction (XRD) technique. It was observed that average particle size of perovskite particle was around 100 nm. In order to probe the local structure and symmetry around lanthanide ions in SrZrO{sub 3}, detailed experimental investigation has been carried out. X-ray absorption near edge fine (XANES) measurements along with their respective emission spectroscopy confirm that on doping lanthanide ion; in cases they were found to get stabilized as trivalent species. Extensive time resolved emission spectroscopy (TRES) on doped samples shows that on doping Sm{sup 3+} in SZO; an efficient energy transfer takes place and Sm{sup 3+} ions are localized both in Sr and Zr positions of SZO. PL decay time shows the presence of two life time values in case of nanocrystalline SrZrO{sub 3}:Sm{sup 3+}: (i) Sm{sup 3+} at Zr{sup 4+} site (τ=500 µs) and (ii) Sm{sup 3+} at Sr{sup 2+} site (τ=1.2 ms) in the ratio of 3:1. Based on TRES for europium doped sample, it was inferred that, two different types of Eu{sup 3+} ions were present in the SZO matrix. The first type was a long lived species present at relatively higher symmetric site of 'Sr{sup 2+}' and the second was a short lived species present at relatively lower symmetric 'Zr{sup 4+}' site which gets selectively excited at 296 nm. Dysprosium ion specifically occupies Zr{sup 4+} site only in SZO. EXAFS studies supported the TRES results. - Highlights: • Site occupancy of lanthanide. • Time resolved emission is explored. • XANES is used for oxidation state determination. • EXAFS for local structure investigation.

  7. Whole-Earth Decompression Dynamics

    OpenAIRE

    Herndon, J. Marvin

    2005-01-01

    The principles of Whole-Earth Decompression Dynamics are disclosed leading to a new way to interpret whole-Earth dynamics. Whole-Earth Decompression Dynamics incorporates elements of and unifies the two seemingly divergent dominant theories of continential displacement, plate tectonics theory and Earth expansion theory. Whole-Earth decompression is the consequence of Earth formation from within a Jupiter-like protoplanet with subsequent loss of gases and ices and concomitant rebounding. The i...

  8. Role of structure imperfection in the formation of the magnetotransport properties of rare-earth manganites with a perovskite structure

    Science.gov (United States)

    Pashchenko, A. V.; Pashchenko, V. P.; Prokopenko, V. K.; Turchenko, V. A.; Revenko, Yu. F.; Mazur, A. S.; Sycheva, V. Ya.; Liedienov, N. A.; Pitsyuga, V. G.; Levchenko, G. G.

    2017-01-01

    The structure, the structure imperfection, and the magnetoresistance, magnetotransport, and microstructure properties of rare-earth perovskite La0.3Ln0.3Sr0.3Mn1.1O3-δ manganites are studied by X-ray diffraction, thermogravimetry, electrical resistivity measurement, magnetic, 55Mn NMR, magnetoresistance measurement, and scanning electron microscopy. It is found that the structure imperfection increases, and the symmetry of a rhombohedrally distorted R3̅ c perovskite structure changes into its pseudocubic type during isovalent substitution for Ln = La3+, Pr3+, Nd3+, Sm3+, or Eu3+ when the ionic radius of an A cation decreases. Defect molar formulas are determined for a real perovskite structure, which contains anion and cation vacancies. The decrease in the temperatures of the metal-semiconductor ( T ms) and ferromagnet-paramagnet ( T C) phase transitions and the increase in electrical resistivity ρ and activation energy E a with increasing serial number of Ln are caused by an increase in the concentration of vacancy point defects, which weaken the double exchange 3 d 4(Mn3+)-2 p 6(O2-)-3 d 3(Mn4+)- V ( a)-3 d 4(Mn3+). The crystal structure of the compositions with Ln = La contains nanostructured planar clusters, which induce an anomalous magnetic hysteresis at T = 77 K. Broad and asymmetric 55Mn NMR spectra support the high-frequency electronic double exchange Mn3+(3 d 4) ↔ O2-(2 p 6) ↔ Mn4+(3 d 3) and indicate a heterogeneous surrounding of manganese by other ions and vacancies. A correlation is revealed between the tunneling magnetoresistance effect and the crystallite size. A composition-structure imperfection-property experimental phase diagram is plotted. This diagram supports the conclusion about a strong influence of structure imperfection on the formation of the magnetic, magnetotransport, and magnetoresistance properties of rare-earth perovskite manganites.

  9. Earth rotation and geodynamics

    Science.gov (United States)

    Bogusz, Janusz; Brzezinski, Aleksander; Kosek, Wieslaw; Nastula, Jolanta

    2015-12-01

    This paper presents the summary of research activities carried out in Poland in 2011-2014 in the field of Earth rotation and geodynamics by several Polish research institutions. It contains a summary of works on Earth rotation, including evaluation and prediction of its parameters and analysis of the related excitation data as well as research on associated geodynamic phenomena such as geocentre motion, global sea level change and hydrological processes. The second part of the paper deals with monitoring of geodynamic phenomena. It contains analysis of geodynamic networks of local, and regional scale using space (GNSS and SLR) techniques, Earth tides monitoring with gravimeters and water-tube hydrostatic clinometer, and the determination of secular variation of the Earth' magnetic field.

  10. Earth science: Extraordinary world

    Science.gov (United States)

    Day, James M. D.

    2016-09-01

    The isotopic compositions of objects that formed early in the evolution of the Solar System have been found to be similar to Earth's composition -- overturning notions of our planet's chemical distinctiveness. See Letters p.394 & p.399

  11. Gambling with the earth

    CERN Multimedia

    Muir, H

    2000-01-01

    The probability that dangerous Earth-devouring particles will be born at a new accelerator in the US may be tiny, but scientists have played down the devastating potential costs in their risk assessments according to a physicist (1 page).

  12. Astronomy: Earth's seven sisters

    Science.gov (United States)

    Snellen, Ignas A. G.

    2017-02-01

    Seven small planets whose surfaces could harbour liquid water have been spotted around a nearby dwarf star. If such a configuration is common in planetary systems, our Galaxy could be teeming with Earth-like planets. See Letter p.456

  13. Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ July 20~31 Rare earth market still went downward, which was mainly led by sluggish demand for didymium products. Weak demand by domestic NdFeB market was attributed to continuous price falling of didymium mischmetal.

  14. Analyzing earth's surface data

    Science.gov (United States)

    Barr, D. J.; Elifrits, C. D.

    1979-01-01

    Manual discusses simple inexpensive image analysis technique used to interpret photographs and scanner of data of Earth's surface. Manual is designed for those who have no need for sophisticated computer-automated analysis procedures.

  15. Managing Planet Earth.

    Science.gov (United States)

    Clark, William C.

    1989-01-01

    Discusses the human use of the planet earth. Describes the global patterns and the regional aspects of change. Four requirements for the cultivation of leadership and institutional competence are suggested. Lists five references for further reading. (YP)

  16. Earliest life on earth

    CERN Document Server

    Golding, Suzanne D

    2010-01-01

    This volume integrates the latest findings on earliest life forms, identified and characterized in some of the oldest rocks on Earth. It places emphasis on the integration of analytical methods with observational techniques and experimental simulations.

  17. 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.

  18. Inovační paradox a regionální inovační strategie

    Directory of Open Access Journals (Sweden)

    Skokan Karel

    2010-12-01

    Full Text Available Konkurenceschopnost firem, regionů i států je určována úrovní produktivity, s jakou využívají alokované zdroje, přitom jedním z hlavních faktorů zvyšování produktivity a konkurenceschopnosti jsou inovace. Současný pohled na inovace je založen na systémovém přístupu, podle kterého firmy neinovují izolovaně, ale v interakci s dalšími účastníky inovačních procesů. Teorie systémů inovací se stala jedním z hlavních východisek k porozumění znalostní společnosti, ale také nerovnoměrností ekonomického rozvoje v zaostalých regionech, které se dají vysvětlit pomocí tzv. inovačního paradoxu. Podle něj se zejména na regionální úrovni projevuje nesoulad mezi nabídkou a poptávkou po finančních zdrojích a nabízených a poskytovaných službách při tvorbě a využívání znalostí na podporu inovací. Příčinou je nízká regionální kapacita tyto znalosti, fondy i služby využívat. Řešením se zdají být regionální inovační strategie, s jejichž podporou začala EU již v 90. letech. Cíl předkládaného článku je dvojí. V teoretické části objasňuje principy systémů inovací a inovačního paradoxu, jehož řešením je rozpracování regionálních inovačních strategií. Ve druhé části analyzuje a shrnuje přístup k regionálním inovačním strategiím v EU a v Česku v posledním desetiletí. Vyvozuje, že formální dokumenty inovačních strategií nemusí být nezbytnou podmínkou rozvoje systémů inovací.

  19. Earth/Lands

    OpenAIRE

    2011-01-01

    Earth is an essentially original and misunderstood raw material with great potential, from the positive environmental and energy ratio, to its admirable capacity to integrate other materials such as stone, wood, brick, lime, vegetable fibres, etc., capable also of constituting the sole material for whole buildings in climactical and geographically extreme situations. Earth offers a great capacity to respond to the housing needs of millions of human beings, not only quantitative needs compa...

  20. Earth rotation and geodynamics

    OpenAIRE

    Bogusz Janusz; Brzezinski Aleksander; Kosek Wieslaw; Nastula Jolanta

    2015-01-01

    This paper presents the summary of research activities carried out in Poland in 2011-2014 in the field of Earth rotation and geodynamics by several Polish research institutions. It contains a summary of works on Earth rotation, including evaluation and prediction of its parameters and analysis of the related excitation data as well as research on associated geodynamic phenomena such as geocentre motion, global sea level change and hydrological processes. The second part of the paper deals wit...

  1. 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.

  2. Toward other Earths

    Science.gov (United States)

    Hatzes, Artie P.

    2016-04-01

    How common are habitable Earth-like planets? This is a key question that drives much of current research in exoplanets. To date, we have discovered over one thousand exoplanets, mostly through the transit method. Among these are Earth-size planets, but these orbit very close to the star (semi-major axis approximately 0.01 Astronomical Units). Potentially rocky planets have also been discovered in a star's habitable zone, but these have approximately twice the radius of the Earth. These certainly do not qualify as Earth "twins". Several hundreds of multi-planet systems have also been discovered, but these are mostly ultra-compact systems with up to seven planets all with orbital distances less than that of Mercury in our solar system. The detection of a planetary system that is the direct analog of our solar system still eludes us. After an overview of the current status of exoplanet discoveries I will discuss the prospects and challenges of finding such Earth analogs from the ground and from future space missions like PLATO. After over two decades of searching, we may well be on the brink of finding other Earths.

  3. Evaluation of DC electric field distribution of PPLP specimen based on the measurement of electrical conductivity in LN2

    Science.gov (United States)

    Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Lee, Jong-Geon; Cho, Jeon-Wook; Ryoo, Hee-Suk; Lee, Bang-Wook

    2013-11-01

    High temperature superconducting (HTS) cable has been paid much attention due to its high efficiency and high current transportation capability, and it is also regarded as eco-friendly power cable for the next generation. Especially for DC HTS cable, it has more sustainable and stable properties compared to AC HTS cable due to the absence of AC loss in DC HTS cable. Recently, DC HTS cable has been investigated competitively all over the world, and one of the key components of DC HTS cable to be developed is a cable joint box considering HVDC environment. In order to achieve the optimum insulation design of the joint box, analysis of DC electric field distribution of the joint box is a fundamental process to develop DC HTS cable. Generally, AC electric field distribution depends on relative permittivity of dielectric materials but in case of DC, electrical conductivity of dielectric material is a dominant factor which determines electric field distribution. In this study, in order to evaluate DC electric field characteristics of the joint box for DC HTS cable, polypropylene laminated paper (PPLP) specimen has been prepared and its DC electric field distribution was analyzed based on the measurement of electrical conductivity of PPLP in liquid nitrogen (LN2). Electrical conductivity of PPLP in LN2 has not been reported yet but it should be measured for DC electric field analysis. The experimental works for measuring electrical conductivity of PPLP in LN2 were presented in this paper. Based on the experimental works, DC electric field distribution of PPLP specimen was fully analyzed considering the steady state and the transient state of DC. Consequently, it was possible to determine the electric field distribution characteristics considering different DC applying stages including DC switching on, DC switching off and polarity reversal conditions.

  4. Synthesis and novel luminescence properties of one-dimension BaMoO{sub 4}:Ln{sup 3+} nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuping; Li, Mingxia; Pan, Kai; Wang, Guofeng, E-mail: wanggf_w@163.com

    2015-12-15

    Highlights: • String BaMoO{sub 4}:Ln{sup 3+} nanobeans were prepared by a hydrothermal method. • The Decay dynamics were performed to study the photoluminescence of the BaMoO{sub 4}:Eu{sup 3+} nanobeans. • For BaMoO{sub 4}:Er{sup 3+}/Eu{sup 3+}, the {sup 2}P{sub 3/2} → {sup 4}I{sub 11/2} and {sup 2}H{sub 11/2}/{sup 4}S{sub 3/2} → {sup 4}I{sub 15/2} transitions were observed. - Abstract: String BaMoO{sub 4}:Ln{sup 3+} (Ln = Eu, Tb, Er, and Gd) nanobeans were prepared by a hydrothermal method. The samples were characterized by transmission electron microscope, scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscope, and Raman spectrometer. Under direct excitation in the charge transfer absorption band, concentration quenching phenomenon occurs and decay dynamics were performed to study the photoluminescence of the string BaMoO{sub 4}:Eu{sup 3+} nanobeans. In the emission spectra of BaMoO{sub 4}:Er{sup 3+}/Eu{sup 3+} under 274 nm excitation, the {sup 2}P{sub 3/2} → {sup 4}I{sub 11/2}, {sup 2}H{sub 11/2} → {sup 4}I{sub 15/2}, and {sup 4}S{sub 3/2} → {sup 4}I{sub 15/2} transitions from Er{sup 3+} ions were observed for the first time. In addition, the photoluminescence properties of BaMoO{sub 4}:Tb{sup 3+}/Eu{sup 3+} and BaMoO{sub 4}:Gd{sup 3+}/Eu{sup 3+} were also investigated.

  5. The Investigation on Welding Processes for SUS316LN Tubes Used in Superconducting Magnetic System of EAST

    Institute of Scientific and Technical Information of China (English)

    Wu Jiefeng; Chen Siyue; Weng Peide; Gao Daming

    2005-01-01

    The force flow cooled superconducting cable-in-conduit conductor (CICC) is used in both of EAST toroidal field (TF) and poloidal field (PF) coils. The conductor consists of multi-stage NbTi superconducting cable and 1.5 mm thick square jacket. The cable is pulled through in a thin wall circular jacket and then compacted to square cross-section conductor. The jacket material is SUS316LN austenitic stainless steel seamless tubes (about 10 m each), which is assembled by butt-welding up to 600 m. The results of the welding procedure investigation and quality assurance procedures carrying out are described in this paper.

  6. Synergistic extraction and separation of Am(III) and Ln(III) with HBMPPT-sulfoxide-HNO3-toluene system

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Some sulfoxides (petroleum sulfoxide -PSO, di-n-octyl sulfoxide -DOSO, etc.) were chosen as synergists to study the synergistic effect on the extraction re action with HBMPPT (4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione) for Am(III), and the synergistic separation for Am(III) and Ln(III). The synergistic extraction ability of PSO is greater than that of DOSO for Am(III). The synergistic complexes may be presented as Am. NO3.(BMPPT)2.HBMPPT.S2 (S indicates PSO or DOSO).

  7. Alpha Radiolysis of Nuclear Solvent Extraction Ligands Used for An(III) and Ln(III) Separations

    Energy Technology Data Exchange (ETDEWEB)

    Mezyk, Stephen P. [California State Univ. (CalState), Long Beach, CA (United States); Mincher, Bruce J. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Nilsson, Mikael [Univ. of California, Irvine, CA (United States)

    2016-08-01

    This document is the final report for the Nuclear Energy Universities Program (NEUP) grant 10-910 (DE-AC07-05ID14517) “Alpha Radiolysis of Nuclear Solvent Extraction Ligands used for An(III) and Ln(III) Separations”. The goal of this work was to obtain a quantitative understanding of the impacts of both low Linear Energy Transfer (LET, gamma-rays) and high LET (alpha particles) radiation chemistry occurring in future large-scale separations processes. This quantitative understanding of the major radiation effects on diluents and ligands is essential for optimal process implementation, and could result in significant cost savings in the future.

  8. Reaction of (CP(2)asterisk-lnH)(2) (ln=Y, La) and CP(2)asterisk-Y(2-C(6)H(4)CH(2)NMe(2)) with esters and amides and molecular-structure of [CP(2)asterisk-Y(mu- ocme=chc(oet)o)](2)

    NARCIS (Netherlands)

    Deelman, B.J; Wierda, F.; Meetsma, A.; Teuben, J.H

    1995-01-01

    The activation of esters and amides by (Cp(2)*LnH)(2) [Ln = Y (1a), Ln = La (1b), Cp*=C(5)Me] and Cp(2)*Y(2-C(6)H(4)CH(2)NMe(2)) (2) is described. Compounds 1a and 1b react with ethyl acetate to form Cp(2)*YOEt (3a) and Cp(2)*LaOEt (30). With 1a and ethyl benzoate a 1:1 mixture of 3a and Cp(2)*YOCH(

  9. Préparation et caractérisation d'oxynitrures Ln2W(O, N) 6- x à structure fluorine déficitaire

    Science.gov (United States)

    Marchand, R.; Antoine, P.; Laurent, Y.

    1993-11-01

    L'action de l'ammoniac sur les tungstates de lanthanides Ln2 WO 6 à 800°C permet de préparer une nouvelle famille d'oxynitrures à structure fluorine déficitaire, de formule Ln2W(O, N) 6- x ( Ln = Nd → Yb, Y). Leur composition générale de type A4X6.6 est intermédiaire entre la stoechiométrie de la fluorine CaF 2( A4X8) et celle de la bixbyite Mn 2O 3( A4X6) qui en dérive. La maille cristalline est cubique avec un paramètre, fonction de la taille du lanthanide, compris entre 5,16 et 5,39 Å. L'étude cristallochimique démontre que les atomes de lanthanide et de tungstène occupent une même position cristallographique. New oxynitrides corresponding to the general formulation Ln2 W(O,N) 6- x ( Ln = Nd → Yb, Y) have been prepared by reaction at 800°C between ammonia and Ln2 WO 6 tungstates, and characterized as defect fluorite type compounds. Their general composition A4X6.6 is intermediate between the Ca F 2( A4X8) fluorite and Mn 2O 3( A4X6) bixbyite stoichiometries. The parameter of the cubic unit cell, comprised between 5.16 and 5.39 Å, depends on the size of the lanthanide. Ln and W atoms occupy a same crystallographic position.

  10. Magnetic and magnetocaloric properties of an unusual family of carbonate-panelled [Ln(III)(6)Zn(III)(2)] cages.

    Science.gov (United States)

    Sethi, Waqas; Sanz, Sergio; Pedersen, Kasper S; Sørensen, Mikkel A; Nichol, Gary S; Lorusso, Giulia; Evangelisti, Marco; Brechin, Euan K; Piligkos, Stergios

    2015-06-14

    The reaction of the pro-ligand H4L, which combines the complementary phenolic oxime and diethanolamine moieties within the same organic framework, with Zn(NO3)2·6H2O and Ln(NO3)3·6H2O in a basic methanolic solution generates a family of isostructural heterometallic coordination compounds of general formula [Ln6Zn2(CO3)5(OH)(H2L)4(H3L)2(H4L)]NO3·xMeOH [Ln = Gd, x = 30 (), Ln = Dy, x = 32 (), Ln = Sm, x = 31 (), Ln = Eu, x = 29 (), Ln = Tb, x = 30 ()]. The octametallic skeleton of the cage describes a heavily distorted [Gd] octahedron capped on two faces by Zn(II) ions. The metal core is stabilised by a series of μ3- and μ4-CO3(2-) ions, originating from the serendipitous fixation of atmospheric CO2. The magnetic properties of all family members were examined via SQUID magnetometry, with the χMT product and VTVB data of the Gd analogue () being independently fitted by numerical diagonalisation to afford the same best-fit parameter JGd-Gd = -0.004 cm(-1). The MCE of complex was elucidated from specific heat data, with the magnetic entropy change reaching a value of 22.6 J kg(-1) K(-1) at T = 1.7 K, close to the maximum entropy value per mole expected from six Gd(III) spins (SGd = 7/2), 23.7 J kg(-1) K(-1).

  11. Chemical durability and resistance to irradiation of LnYSiAlO (Ln=La or Ce) glasses, potential immobilization matrix of minor actinides; Durabilite chimique et comportement a l'irradiation des verres quaternaires LnYSiAlO (Ln = La ou Ce), matrice potentielle d'immobilisation d'actinides mineurs trivalents

    Energy Technology Data Exchange (ETDEWEB)

    Gavarini, St

    2002-11-01

    Rare earth aluminosilicate glasses are known for their interesting mechanical and optical properties. Recent studies have shown that their chemical durability was very good too, such they have the potential to be used in the nuclear industry for the specific immobilization of trivalent actinides. Initial dissolution rates of LaYSiAlO and CeYSiAlO were determined using a Soxhlet device (dynamic leaching). The differences linked to the nature of the rare earth element were studied by synthesizing analogous glasses that only differed in their rare earth element composition (%at.): Y-5%, La-5 %, Si-15%, Al-10% O-65%. The influence of pH on the dissolution mechanisms and kinetics was also studied by static leaching tests performed in dilute solutions of NaOH or HNO{sub 3}. Electronic defects and collision cascades, induced by a-disintegration of radioelements confined in storage matrix, can cause important modifications in the glass structure and, thus, influence its chemical durability. To simulate these effects, glass samples were irradiated with {beta} particles and heavy ions accelerated to 2,5 MeV and 200 keV, respectively. Monoliths were then leached in static bi-distilled water (pH{>=}{>=} 5.5) for one month in an autoclave heated to 90 degrees C. Initially, the structural changes caused by irradiation were determined using Raman, NMR and EPR spectroscopies. Ion {mu}-beams, SEM-EDS and XPS analysis were also performed to evaluate the potential modifications of the superficial composition. Finally, the leaching behavior was studied, for both irradiated and unirradiated samples, through solution and solid elementary characterization. (author)

  12. A family of rare earth molybdenum bronzes: Oxides consisting of periodic arrays of interacting magnetic units

    Energy Technology Data Exchange (ETDEWEB)

    Schneemeyer, L.F. [Department of Chemistry, Montclair State University, Montclair, NJ 07043 (United States); Siegrist, T., E-mail: tsiegrist@fsu.edu [Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL 32310 (United States); National High Magnetic Field Laboratory, Tallahassee, FL 32310 (United States); Besara, T. [National High Magnetic Field Laboratory, Tallahassee, FL 32310 (United States); Lundberg, M. [Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL 32310 (United States); National High Magnetic Field Laboratory, Tallahassee, FL 32310 (United States); Sun, J. [Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL 32310 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6056 (United States); Singh, D.J. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6056 (United States)

    2015-07-15

    The family of rare earth molybdenum bronzes, reduced ternary molybdates of composition LnMo{sub 16}O{sub 44,} was synthesized and a detailed structural study carried out. Bond valence sum (BVS) calculations clearly show that the molybdenum ions in tetrahedral coordination are hexavalent while the electron count in the primitive unit cell is odd. Yet, measurements show that the phases are semiconductors. The temperature dependence of the magnetic susceptibility of samples containing several different rare earth elements was measured. These measurements verified the presence of a 6.5 K magnetic phase transition not arising from the rare earth constituent, but likely associated with the unique isolated ReO{sub 3}-type Mo{sub 8}O{sub 36} structural subunits in this phase. To better understand the behavior of these materials, electronic structure calculations were performed within density functional theory. Results suggest a magnetic state in which these structural moieties have an internal ferromagnetic arrangement, with small ~1/8 μ{sub B} moments on each Mo. We suggest that the Mo{sub 8}O{sub 36} units behave like pseudoatoms with spin 1/2 derived from a single hole distributed over the eight Mo atoms that are strongly hybridized with the O atoms of the subunit. Interestingly, while the compound is antiferromagnetic, our calculations suggest that a field-stabilized ferromagnetic state, if achievable, will be a narrow band half-metal. - Graphical abstract: LnMo{sub 16}O{sub 44} phases comprise corner sharing tetrahedral and octahedral molybdenum ions. The MoO{sub 6} octahedra form Mo{sub 8}O{sub 36} units that are well separated and act like pseudo-atoms, accommodating 11 electrons each. - Highlights: • Single crystal X-ray diffraction refinements of LnMo{sub 16}O{sub 44} single crystals for Ln=Ce, Pr, Nd, Tb, Dy and Ho. • DFT calculations based on LaMo{sub 16}O{sub 44}. • [Mo{sub 8}O{sub 36}] units behaving as superatoms with a net magnetic moment of 1 µ

  13. Primer caso de hemoglobina Köln (codon98 GTG>ATG en Costa Rica First case of hemoglobin Köln (codon98 GTG>ATG in Costa Rica

    Directory of Open Access Journals (Sweden)

    Walter Cartín

    2010-03-01

    Full Text Available La exposición a ciertos medicamentos puede provocar anemia hemolítica con presencia de cuerpos de Heinz en sangre periférica. Esta anemia puede presentarse por sobredosis de medicamentos, tanto en individuos sanos como en personas con deficiencias enzimáticas como la glucosa-6-fosfato deshidrogenasa, o en presencia de hemoglobinas inestables. Este reporte muestra un caso de anemia hemolítica con cuerpos de Heinz, debido a la presencia de una hemoglobina inestable, cuyos estudios moleculares y HPLC confirmaron el primer caso descrito de hemoglobina Köln (Val98Met en Costa Rica.Exposure to certain drugs may result in hemolytic anemia with the appearance of Heinz-bodies in red blood cells. This type of hemolytic anemia may occur by simple drug overdosage in absence of any known abnormality, such as in normal persons or in patients with erithroid enzyme defects (e.g. G6PD deficiency or unstable hemoglobins.¹ The present report shows a Heinz-body hemolytic anemia because of an abnormal hemoglobin. High pressure liquid chromatography (HPLC and molecular analysis confirmed the first case of Hemoglobin Köln in Costa Rica.

  14. Hydrothermal synthesis and structural characterization of a family of lanthanide tartrates: [Ln 2(C 4H 4O 6) 3(H 2O) 3]·1.5H 2O (Ln = La, Ce, Pr, Nd, Sm)

    Science.gov (United States)

    Athar, Muhammad; Li, Guanghua; Shi, Zhan; Chen, Yan; Feng, Shouhua

    2008-12-01

    Coordination polymers containing lanthanides with tartaric acid [Ln 2(C 4H 4O 6) 3(H 2O) 3]·1.5H 2O (Ln = La, Ce, Pr, Nd, Sm and C 4H 4O 6 = D(-) or L(+) tartrate anion) have been synthesized using hydrothermal techniques and characterized by single crystal X-ray diffraction. The compounds are all isotypic with a monoclinic crystal system in the P2 1/ n space group. The asymmetric units of coordination polymers contain two metal centers having different coordination environments. One metal is bonded to four tartrate groups having three D and one L isomers (or three L and one D isomers), whereas the other metal is bonded to five tartrate groups having two D and three L isomers (or two L and three D isomers). Each trivalent metal center is coordinated to nine oxygen atoms that originate from carboxylate and hydroxyl groups of the tartrate anions and water molecules. These new polymers have three-dimensional structures containing open channels that are occupied by non-coordinating water molecules. Thermogravimetric and differential thermal analyses and adsorption of nitrogen have also been studied for these compounds.

  15. Chemical and structural changes in Ln{sub 2}NiO{sub 4+δ} (Ln=La, Pr or Nd) lanthanide nickelates as a function of oxygen partial pressure at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Flura, Aurélien; Dru, Sophie; Nicollet, Clément; Vibhu, Vaibhav; Fourcade, Sébastien; Lebraud, Eric; Rougier, Aline; Bassat, Jean-Marc; Grenier, Jean-Claude, E-mail: grenier@icmcb-bordeaux.cnrs.fr

    2015-08-15

    The chemical stability of lanthanide nickelates Ln{sub 2}NiO{sub 4+δ} (Ln=La, Pr or Nd) has been studied in the temperature range 25–1300 °C, either in air or at low pO{sub 2} (down to 10{sup −4} atm). Thermal gravimetry analysis (TGA) measurements coupled with X-ray diffraction (XRD) characterization have shown that all compounds retain their K{sub 2}NiF{sub 4}-type structure in these conditions, while remaining over-stoichiometric in oxygen up to 1000 °C. Only Nd{sub 2}NiO{sub 4+δ} starts to decompose into Nd{sub 2}O{sub 3} and NiO above 1000 °C, at pO{sub 2}=10{sup −4} atm. In addition, a careful analysis of the lanthanide nickelates structural features has been performed by in situ XRD, as a function of temperature and pO{sub 2}. For all compounds, a structural transition has been always observed in the temperature range 200–400 °C, in air or at pO{sub 2}=10{sup −4} atm. In addition, their cell volume did not vary upon the variation of the oxygen partial pressure. Therefore, these materials do not exhibit a chemical expansion in these conditions, which is beneficial for a fuel cell application as cathode layers. Additional dilatometry measurements have revealed that a temperature as high as 950 °C for Pr{sub 2}NiO{sub 4+δ} or 1100 °C for La{sub 2}NiO{sub 4+δ} and Nd{sub 2}NiO{sub 4+δ} has to be reached in order to begin the sintering of the material particles, which is of primary importance to obtain an efficient electronic/ionic conduction in the corresponding designed cathode layers. Besides, excellent matching was found between the thermal expansion coefficients of lanthanide nickelates and SOFC electrolytes such as 8wt% yttria stabilized zirconia (8YSZ) or Ce{sub 0.8}Gd{sub 0.2}O{sub 2−δ} (GDC), at least from 400 °C up to 1400 °C in air or up to 1200 °C at pO{sub 2}=10{sup −4} atm. - Graphical abstract: This study reports the good chemical stability of oxygen overstoichiometric Ln2NiO4+δ(Ln = La, Pr or Nd) at high temperatures

  16. The earth's hydrological cycle

    CERN Document Server

    Bonnet, R-M; Calisto, M; Destouni, G; Gurney, R; Johannessen, J; Kerr, Y; Lahoz, WA; Rast, M

    2014-01-01

    This book gives a comprehensive presentation of our present understanding of the Earth's Hydrological cycle and the problems, consequences and impacts that go with this topic. Water is a central component in the Earth's system. It is indispensable for life on Earth in its present form and influences virtually every aspect of our planet's life support system. On relatively short time scales, atmospheric water vapor interacts with the atmospheric circulation and is crucial in forming the Earth's climate zones. Water vapor is the most powerful of the greenhouse gases and serves to enhance the tropospheric temperature. The dominant part of available water on Earth resides in the oceans. Parts are locked up in the land ice on Greenland and Antarctica and a smaller part is estimated to exist as groundwater. If all the ice over the land and all the glaciers were to melt, the sea level would rise by some 80 m. In comparison, the total amount of water vapor in the atmosphere is small; it amounts to ~ 25 kg/m2, or the ...

  17. The Sun and Earth

    Science.gov (United States)

    Gopalswamy, Natchimuthuk

    2012-01-01

    Thus the Sun forms the basis for life on Earth via the black body radiation it emits. The Sun also emits mass in the form of the solar wind and the coronal mass ejections (CMEs). Mass emission also occurs in the form of solar energetic particles (SEPs), which happens during CMEs and solar flares. Both the mass and electromagnetic energy output of the Sun vary over a wide range of time scales, thus introducing disturbances on the space environment that extends from the Sun through the entire heliosphere including the magnetospheres and ionospheres of planets and moons of the solar system. Although our habitat is located in the neutral atmosphere of Earth, we are intimately connected to the non-neutral space environment starting from the ionosphere to the magnetosphere and to the vast interplanetary space. The variability of the solar mass emissions results in the interaction between the solar wind plasma and the magnetospheric plasma leading to huge disturbances in the geospace. The Sun ionizes our atmosphere and creates the ionosphere. The ionosphere can be severely disturbed by the transient energy input from solar flares and the solar wind during geomagnetic storms. The complex interplay between Earth's magnetic field and the solar magnetic field carried by the solar wind presents varying conditions that are both beneficial and hazardous to life on earth. This seminar presents some of the key aspects of this Sun-Earth connection that we have learned since the birth of space science as a scientific discipline some half a century ago.

  18. Modeling the earth system

    Energy Technology Data Exchange (ETDEWEB)

    Ojima, D. [ed.

    1992-12-31

    The 1990 Global Change Institute (GCI) on Earth System Modeling is the third of a series organized by the Office for Interdisciplinary Earth Studies to look in depth at particular issues critical to developing a better understanding of the earth system. The 1990 GCI on Earth System Modeling was organized around three themes: defining critical gaps in the knowledge of the earth system, developing simplified working models, and validating comprehensive system models. This book is divided into three sections that reflect these themes. Each section begins with a set of background papers offering a brief tutorial on the subject, followed by working group reports developed during the institute. These reports summarize the joint ideas and recommendations of the participants and bring to bear the interdisciplinary perspective that imbued the institute. Since the conclusion of the 1990 Global Change Institute, research programs, nationally and internationally, have moved forward to implement a number of the recommendations made at the institute, and many of the participants have maintained collegial interactions to develop research projects addressing the needs identified during the two weeks in Snowmass.

  19. Low Cycle Fatigue Behavior of 316LN Stainless Steel Alloyed with Varying Nitrogen Content. Part I: Cyclic Deformation Behavior

    Science.gov (United States)

    Prasad Reddy, G. V.; Sandhya, R.; Sankaran, S.; Mathew, M. D.

    2014-10-01

    In this study, the influence of cyclic strain amplitude on the evolution of cyclic stress-strain response and the associated cyclic deformation mechanisms in 316LN stainless steel with varying nitrogen content (0.07 to 0.22 wt pct) is reported in the temperature range 773 K to 873 K (500 °C to 600 °C). Two mechanisms, namely dynamic strain aging and secondary cyclic hardening, are found to strongly influence the cyclic stress response. Deformation substructures associated with both the mechanisms showed planar mode of deformation. These mechanisms are observed to be operative over certain combinations of temperature and strain amplitude. For strain amplitudes >0.6 pct, wavy or mixed mode of deformation is noticed to suppress both the mechanisms. Cyclic stress-strain curves revealed both single and dual-slope behavior depending on the test temperature. Increase in nitrogen content is found to increase the tendency toward planar mode of deformation, while increase in strain amplitude leads to transition from planar slip bands to dislocation cell/wall structure formation, irrespective of the nitrogen content in 316LN stainless steel.

  20. Návrh odstředivého čerpadla metodami diferenciální geometrie

    OpenAIRE

    Sloupenský, Zdeněk

    2011-01-01

    Disertační práce se zabývá novým přístupem návrhu oběžného kola, lopatky a spirály odstředivého čerpadla. Matematický model proudění v meridiálním řezu oběžného kola i spirály se opírá o nástroje diferenciální geometrie aplikované na Bézieroy plochy. Tato již dříve představená teorie je v této práci hlouběji rozpracována a závěry jsou využity při návrhu součástí odstředivého čerpadla, které přicházejí do styku s kapalinou. Hlavním výstupem práce je matematický model a na jeho základě vytvořen...

  1. Analytic amplitudes for hadronic forward scattering and the Heisenberg ln{sup 2} s behaviour of total cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Nicolescu, Basarab [LPNHE, Unite de Recherche des Universites Paris 6 et Paris 7, associee au CNRS, Theory Group, Universite Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris Cedex 05 (France)

    2004-07-01

    We consider several classes of analytic parametrizations of hadronic scattering amplitudes (the COMPETE analysis), and compare their predictions to all available forward data (pp, {pi}p, Kp, {gamma}p, {gamma}{gamma}, {sigma}p). Although these parametrizations are very close for {radical}s {>=} 9 GeV, it turns out that they differ markedly at low energy, where a universal Pomeron term {approx} ln{sup 2} s enables one to extend the fit down to {radical}s = 4 GeV. We present predictions on the total cross sections and on the ratio of the real part to the imaginary part of the elastic amplitude ({rho} parameter) for present and future pp colliders, and on total cross sections for {gamma}p {yields} hadrons at cosmic-ray energies and for it{gamma}{gamma} {yields} hadrons up to {radical}s = 1 TeV. The ln{sup 2} s behaviour of total cross sections, first obtained by Heisenberg 50 years ago, receives now increased interest both on phenomenological and theoretical levels. We present a modification of the Heisenberg's model in connection with the presence of glueballs and we show that it leads to a realistic description of all existing hadron total cross-sections data, in agreement with the COMPETE analysis.

  2. Synthesis of Multicolor Core/Shell NaLuF₄:Yb(3+)/Ln(3+)@CaF₂ Upconversion Nanocrystals.

    Science.gov (United States)

    Li, Hui; Hao, Shuwei; Yang, Chunhui; Chen, Guanying

    2017-02-07

    The ability to synthesize high-quality hierarchical core/shell nanocrystals from an efficient host lattice is important to realize efficacious photon upconversion for applications ranging from bioimaging to solar cells. Here, we describe a strategy to fabricate multicolor core @ shell α-NaLuF₄:Yb(3+)/Ln(3+)@CaF₂ (Ln = Er, Ho, Tm) upconversion nanocrystals (UCNCs) based on the newly established host lattice of sodium lutetium fluoride (NaLuF₄). We exploited the liquid-solid-solution method to synthesize the NaLuF₄ core of pure cubic phase and the thermal decomposition approach to expitaxially grow the calcium fluoride (CaF₂) shell onto the core UCNCs, yielding cubic core/shell nanocrystals with a size of 15.6 ± 1.2 nm (the core ~9 ± 0.9 nm, the shell ~3.3 ± 0.3 nm). We showed that those core/shell UCNCs could emit activator-defined multicolor emissions up to about 772 times more efficient than the core nanocrystals due to effective suppression of surface-related quenching effects. Our results provide a new paradigm on heterogeneous core/shell structure for enhanced multicolor upconversion photoluminescence from colloidal nanocrystals.

  3. Une nouvelle famille de pyrochlores: les oxynitrures Ln2Ta 2O 5N 2. Préparation et étude cristallochimique

    Science.gov (United States)

    Pors, F.; Marchand, R.; Laurent, Y.

    1993-11-01

    Par action de l'ammoniac à 900-950°C sur les tantalates de terres rares LnTaO 4, on a mis en évidence une nouvelle famille d'oxynitrures dont la structure est de type pyrochlore. Ces composés Ln2Ta 2O 5N 2 ont été obtenus pour les lanthanides de rayon inférieur ou égal à celui du néodyme, ainsi que pour l'yttrium. La maille cristalline est de symétrie cubique (10,2 Å < a < 10,6 Å). La stoechiométrie anionique impose un désordre oxygène-azote au moins partiel entre les deux sites cristallographiques correspondants. New oxynitrides Ln2 Ta 2O 5N 2 ( Ln = Nd → Yb, Y), belonging to the pyrochlore type structure, have been prepared by heating at 900-950°C the LnTaO 4 corresponding tantalates. The a parameter of the cubic unit cell is comprised between 10.2 and 10.6 Å. Because of the anionic stoichiometry, oxygen and nitrogen atoms are disordered, at least partially.

  4. Examination of Compatibility of Potentially Cavitation-Resistant Modifications of Type 316LN Stainless Steel with Mercury in a Thermal Convection Loop

    Energy Technology Data Exchange (ETDEWEB)

    Pawel, SJ

    2002-08-29

    A 316L stainless steel thermal convection loop (TCL) containing a variety of stainless steel coupons circulated mercury for 2000 h. The TCL conditions included a maximum temperature of 307 C, a maximum temperature gradient of 90 C, and a Hg velocity of about 1.4 m/min. In addition to mill-annealed/surface-ground 316LN coupons serving as the baseline material, other coupons included 316LN that was 50% cold-worked, 316LN that was given a proprietary surface hardening treatment termed ''kolsterizing,'' and Nitronic 60. The purpose of this test was to examine Hg compatibility with these modest variations of annealed 31 6LN stainless steel that are considered potential improvements over annealed 31 6LN for cavitation-erosion resistance in the Spallation Neutron Source (SNS) target containment system. The results indicated negligible weight change for each coupon type, no significant indication of attack or surface roughening, and generally no interaction with Hg.

  5. New Composites LnBDC@AC and CB[6]@AC: From Design toward Selective Adsorption of Methylene Blue or Methyl Orange

    Science.gov (United States)

    Santos, Guilherme de C.; Barros, Amanda L.; de Oliveira, Carlos A. F.; da Luz, Leonis L.; da Silva, Fausthon F.; Demets, Grégoire J.-F.; Alves Júnior, Severino

    2017-01-01

    New porous composites LnBDC@AC (AC = Activated carbon, Ln = Eu and Gd and BDC = 1,4-benzenedicaboxylate) and CB[6]@AC (CB[6] = Cucurbit[6]uril) were obtained using hydrothermal route. The LnBDC and CB[B] are located inside the pore of the carbon materials as was observed in SEM-EDS, XRPD and FT-IR analysis. Porosimetry analysis showed values typically between AC and LnBDC material, with pore size and surface area, respectively, 29,56 Å and 353.98 m2g-1 for LnBDC@AC and 35,53 Å and 353.98 m2g-1 for CB[6]@AC. Both materials showed good absorptive capacity of metil orange (MO) and methylene blue (MB) with selectivity as a function of pH. For acid pH, both materials present selectivity by MB and alkaline pH for MO, with notable performance for CB[6]@AC. Additionally, europium luminescence was used as structural probe to investigate the coordination environment of Eu3+ ions in the EuBDC@AC composite after adsorption experiment. PMID:28107440

  6. Anomalous thermal expansion in rare-earth gallium perovskites: a comprehensive powder diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Senyshyn, A; Trots, D M; Engel, J M; Ehrenberg, H; Fuess, H [Institute for Materials Science, Darmstadt University of Technology, D-64287 Darmstadt (Germany); Vasylechko, L [Lviv Polytechnic National University, 12 Bandera Street, 79013 Lviv (Ukraine); Hansen, T [Institut Max von Laue-Paul Langevin, 38042 Grenoble Cedex 9 (France); Berkowski, M [Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, 02-668 Warsaw (Poland)

    2009-04-08

    Crystal structures of rare-earth gallium perovskites LaGaO{sub 3}, PrGaO{sub 3}, NdGaO{sub 3} and Pr{sub 1-x}Nd{sub x}GaO{sub 3} (x = 0.25, 0.50, 0.75) solid solutions were investigated in the temperature range 12-300 K by high-resolution powder diffraction using synchrotron or neutron radiation. The previously reported negative thermal expansion in the b direction of the PrGaO{sub 3} lattice has been found to be persistent in Pr{sub 1-x}Nd{sub x}GaO{sub 3} solid solutions and its magnitude has been revealed as proportional to the amount of praseodymium. Evaluation of the obtained temperature evolution of cell dimensions indicated a weak anomalous behaviour of the b lattice parameter in NdGaO{sub 3}, and its origin is supposed to be the same as in PrGaO{sub 3}, i.e. a coupling of the crystal electric field levels with phonon excitations of about 23-25 meV energy. The performed bond length analysis revealed an anomalous behaviour of both LnO{sub 12} (Ln-rare-earth) and GaO{sub 6} coordination polyhedra, which can be a structural manifestation of anomalous thermal expansion in the considered compounds.

  7. Molecular heterometallic hydride clusters composed of rare-earth and d-transition metals.

    Science.gov (United States)

    Shima, Takanori; Luo, Yi; Stewart, Timothy; Bau, Robert; McIntyre, Garry J; Mason, Sax A; Hou, Zhaomin

    2011-09-18

    Heteromultimetallic hydride clusters containing both rare-earth and d-transition metals are of interest in terms of both their structure and reactivity. However, such heterometallic complexes have not yet been investigated to a great extent because of difficulties in their synthesis and structural characterization. Here, we report the synthesis, X-ray and neutron diffraction studies, and hydrogen addition and release properties of a family of rare-earth/d-transition-metal heteromultimetallic polyhydride complexes of the core structure type 'Ln(4)MH(n)' (Ln = Y, Dy, Ho; M = Mo, W; n = 9, 11, 13). Monitoring of hydrogen addition to a hydride cluster such as [{(C(5)Me(4)SiMe(3))Y}(4)(μ-H)(9)Mo(C(5)Me(5))] in a single-crystal to single-crystal process by X-ray diffraction has been achieved for the first time. Density functional theory studies reveal that the hydrogen addition process is cooperatively assisted by the Y/Mo heteromultimetallic sites, thus offering unprecedented insight into the hydrogen addition and release process of a metal hydride cluster.

  8. Protonation and structural/chemical stability of Ln{sub 2}NiO{sub 4+δ} ceramics vs. H{sub 2}O/CO{sub 2}: High temperature/water pressure ageing tests

    Energy Technology Data Exchange (ETDEWEB)

    Upasen, S. [Sorbonne Universités, UPMC Univ Paris 06, UMR 8233, MONARIS, 75005 Paris (France); CNRS-IP2CT, UMR 8233, MONARIS, F-75005 Paris (France); Batocchi, P.; Mauvy, F. [ICMCB, ICMCB-CNRS-IUT-Université de Bordeaux, 33608 Pessac Cedex (France); Slodczyk, A. [Sorbonne Universités, UPMC Univ Paris 06, UMR 8233, MONARIS, 75005 Paris (France); CNRS-IP2CT, UMR 8233, MONARIS, F-75005 Paris (France); Colomban, Ph., E-mail: philippe.colomban@upmc.fr [Sorbonne Universités, UPMC Univ Paris 06, UMR 8233, MONARIS, 75005 Paris (France); CNRS-IP2CT, UMR 8233, MONARIS, F-75005 Paris (France)

    2015-02-15

    Highlights: • High temperature/water pressure autoclave is used to study the reaction/corrosion at SOFC/HTSE electrode. • High stability of Pr{sub 2}NiO{sub 4+δ} (PNO) and Nd{sub 2}NiO{sub 4+δ} (NNO) dense ceramics vs. water pressure is demonstrated. • Protonated rare-earth nickelates retain the perovskite-type structure and their H-content is determined. • Very low laser illumination power is required to avoid RE nickelate phase transition. • Nickelates show increasing stability from La to Pr/Nd vs. CO{sub 2}-rich high temperature water vapor. - Abstract: Mixed ionic-electronic conductors (MIEC) such as rare-earth nickelates with a general formula Ln{sub 2}NiO{sub 4+δ} (Ln = La, Pr, Nd) appear as potential for energy production and storage systems: fuel cells, electrolysers and CO{sub 2} converters. Since a good electrode material should exhibit important stability in operating conditions, the structural and chemical stability of different nickelate-based, well-densified ceramics have been studied using various techniques: TGA, dilatometry, XRD, Raman scattering and IR spectroscopy. Consequently, La{sub 2}NiO{sub 4+δ} (LNO), Pr{sub 2}NiO{sub 4+δ} (PNO) and Nd{sub 2}NiO{sub 4+δ} (NNO) have been exposed during 5 days to high water vapor pressure (40 bar) at intermediate temperature (550 °C) in an autoclave device, the used water being almost free or saturated with CO{sub 2}. Such protonation process offers an accelerating stability test and allows the choice of the most pertinent composition for industrial applications requiring a selected material with important life-time. In order to understand any eventual change of crystal structure, the ceramics were investigated in as-prepared, pristine state as well as after protonation and deprotonation (due to thermal treatment till 1000 °C under dry atmosphere). The results show the presence of traces or second phases originating from undesirable hydroxylation and carbonation, detected in the near

  9. Luminescence de l'europium divalent dans les borates doubles BaLnB9O16(Ln=La, Gd, Y) et de l'europium trivalent dans les phosphates d'Yttrium et de gadolinium en vue d'application à la visualisation

    OpenAIRE

    Cong Tuan, Dinh

    2000-01-01

    En vue d'application à l'éclairage ou dans les dispositifs de visualisation à plama, on a étudié la luminescence de l'ion Eu2+ dans les borates BaLnB9O16 (Ln = La, Ce, Gd, Y) et de l'ion Eu3+ dans les diverses phases des systèmes Gd2O3-P2O5 et Y2O3-P2O5. Des informations sur les structures des réseaux-hôtes lorsqu'elles étaient inconnues, ont pu être obtenues par diffraction X et spectroscopie Raman. Pour Ln = Y, Gd, les borates BaLnB9O16:Eu2+ présentent une émission dans le bleu stable...; n...

  10. Investigation of Polyacrylate Anion-Exchangers for Separation of Rare Earth Element Complexes with EDTA

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The rare earth complexes with EDTA, Ln(edta), show an unusual sequence of affinity for the anion-exchangers. The sorption and chromatographic separation of Y3+ for Nd3+ complexes with EDTA was studied by using the strongly basic gel and macroporous polyacrylate anion-exchangers, Amberlite IRA 458 and Amberlite 958, and the weakly basic gel polyacrylate anion-exchanger, Amberlite IRA-68. The investigations on sorption and separation of rare earth complexes with EDTA on the polyacrylate anion-exchangers applied mainly in the environment protection so far indicate that they can be applied in anionexchange separation of lanthanide complexes with aminopolycarboxylic acids. It was shown that the weakly basic polyacrylate gel anion-exchanger Amberlite IRA-68 is the most effective in purification of Y3+ from Nd3+ in comparison with the strongly basic anion-exchangers of this type.

  11. Distribution of Rare Earth Metals in Technogenic Wastes of Energy Enterprises (Results of the Laboratory Studies

    Directory of Open Access Journals (Sweden)

    Alexandr Ivanovich Khanchuk

    2016-12-01

    Full Text Available The results of the research interaction between ash and slag samples from Vladivostok TPP’s landfills saturated with underburning and ammonium hydrodifluoride were given. It was found out that the reactions of the main components of a concentrate with NH4HF2 are flowing with creation of complex ammonium fluoro-metalate. It is shown that the distribution of REM (rare earth metals between foam and heavier products is going during the flotation process of carbon-containing ash and slag samples without significant concentrating. It is shown that the water leaching of fluoridated product lets transfer silicone, aluminum and iron salts into solution and concentrate rare earth elements in insoluble residue in the form of complex salts of NaLnF4 general formula. We propose a schematic diagram of hydrodifluoride recycling of carbon-containing sample, which provides concentrating of REM with incomplete separation of macro-components.

  12. Better Than Earth

    CERN Document Server

    Heller, René

    2015-01-01

    Do We Inhabit The Best O All Possible Worlds? German mathematician Gottfried Leibniz thought so, writing in 1710 that our planet, warts and all, must be the most optimal one imaginable. Leibniz's idea was roundly scorned as unscientific wishful thinking, most notably by French author Voltaire in his magnum opus, Candide. Yet Leibniz might find sympathy from at least one group of scientists - the astronomers who have for decades treated Earth as a golden standard as they search for worlds beyond our own solar system. Because earthlings still know of just one living world - our own - it makes some sense to use Earth as a template in the search for life elsewhere, such as in the most Earth-like regions of Mars or Jupiter's watery moon Europa. Now, however, discoveries of potentially habitable planets orbiting stars other than our sun - exoplanets, that is - are challenging that geocentric approach.

  13. Better Than Earth

    Science.gov (United States)

    Heller, René

    2015-01-01

    Do we inhabit the best of all possible worlds? German mathematician Gottfried Leibniz thought so, writing in 1710 that our planet, warts and all, must be the most optimal one imaginable. Leibniz's idea was roundly scorned as unscientific wishful thinking, most notably by French author Voltaire in his magnum opus, Candide. Yet Leibniz might find sympathy from at least one group of scientists - the astronomers who have for decades treated Earth as a golden standard as they search for worlds beyond our own solar system. Because earthlings still know of just one living world - our own - it makes some sense to use Earth as a template in the search for life elsewhere, such as in the most Earth-like regions of Mars or Jupiter's watery moon Europa. Now, however, discoveries of potentially habitable planets orbiting stars other than our sun - exoplanets, that is - are challenging that geocentric approach.

  14. Geoneutrino and Hydridic Earth model

    CERN Document Server

    Bezrukov, Leonid

    2013-01-01

    Uranium, Thorium and Potassium-40 abundances in the Earth were calculated in the frame of Hydridic Earth model. Terrestrial heat producton from U, Th and K40 decays was calculated also. We must admit the existance of Earth expansion process to understand the obtained large value of terrestrial heat producton. The geoneutrino detector with volume more than 5 kT (LENA type) must be constructed to definitely separate between Bulk Silicat Earth model and Hydridic Earth model.

  15. Fabrication of lanthanide decatungstate [Ln{sup III/IV}(W{sub 5}O{sub 18}){sub 2}]{sup 8-/9-} (Ln = Ce{sup IV/III}, Eu{sup III}, and Er{sup III}) thin films using spin-coating from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, Yusuke; Ishihara, Noritaka [Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Fukaya, Keisuke; Srifa, Atthapon [National Nanotechnology Center (NANOTEC), 111 Thailand Science Park, Paholyothin Rd, Klong 1, Klong Luang, Phathumthani 12120 (Thailand); Naruke, Haruo, E-mail: hnaruke@res.titech.ac.jp [Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)

    2012-04-05

    Highlights: Black-Right-Pointing-Pointer Lanthanide decatungstate (LnW{sub 10}) thin-films were fabricated by a spin-coating method. Black-Right-Pointing-Pointer We obtained transparent films of good quality without hybrid with organic cations. Black-Right-Pointing-Pointer A self-organized periodic structure was formed spontaneously. Black-Right-Pointing-Pointer Optical and luminescence properties were similar to those of LnW{sub 10} (Ln = Eu) crystals. - Abstract: Lanthanide decatungstate Na{sub m}[Ln(W{sub 5}O{sub 18}){sub 2}]{center_dot}nH{sub 2}O (LnW{sub 10}: m = 9 for Ln = Eu{sup III}, Ce{sup III}, and Er{sup III}; m = 8 for Ln = Ce{sup IV}) thin films were fabricated on quartz glass substrates by spin-coating using water as the solvent. In this method, we exclude hybrids with organic materials to avoid undesirable modification of the original photophysical properties of LnW{sub 10}. The resultant films were characterized by X-ray diffraction (XRD), scanning probe microscopy (SPM), optical absorption, and photoluminescence spectroscopy. All the films had high transparency, flatness, and homogeneity. The thickness of the films was controllable by adjusting the concentration of LnW{sub 10} solution. XRD measurements showed that the [Ln{sup III/IV}(W{sub 5}O{sub 18}){sub 2}]{sup 9-/8-} molecules in all the films were self-organized, forming a layer-like periodic structure with a periodicity of {approx}14 Angstrom-Sign in the early stage, followed by time-dependent structural changes. The Eu{sup III}W{sub 10} film exhibited photoluminescence upon excitation at {approx}250 nm; the film's spectrum and lifetime were similar to those of the crystal sample. These results demonstrate that the molecular environment in LnW{sub 10} thin films is similar to that found in solid crystals.

  16. How Big is Earth?

    Science.gov (United States)

    Thurber, Bonnie B.

    2015-08-01

    How Big is Earth celebrates the Year of Light. Using only the sunlight striking the Earth and a wooden dowel, students meet each other and then measure the circumference of the earth. Eratosthenes did it over 2,000 years ago. In Cosmos, Carl Sagan shared the process by which Eratosthenes measured the angle of the shadow cast at local noon when sunlight strikes a stick positioned perpendicular to the ground. By comparing his measurement to another made a distance away, Eratosthenes was able to calculate the circumference of the earth. How Big is Earth provides an online learning environment where students do science the same way Eratosthenes did. A notable project in which this was done was The Eratosthenes Project, conducted in 2005 as part of the World Year of Physics; in fact, we will be drawing on the teacher's guide developed by that project.How Big Is Earth? expands on the Eratosthenes project by providing an online learning environment provided by the iCollaboratory, www.icollaboratory.org, where teachers and students from Sweden, China, Nepal, Russia, Morocco, and the United States collaborate, share data, and reflect on their learning of science and astronomy. They are sharing their information and discussing their ideas/brainstorming the solutions in a discussion forum. There is an ongoing database of student measurements and another database to collect data on both teacher and student learning from surveys, discussions, and self-reflection done online.We will share our research about the kinds of learning that takes place only in global collaborations.The entrance address for the iCollaboratory is http://www.icollaboratory.org.

  17. Alkaline earth metal thioindates

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov-Ehmin, B.N.; Ivlieva, V.I.; Filatenko, L.A.; Zajtsev, B.E.; Kaziev, G.Z.; Sarabiya, M.G.

    1984-08-01

    Alkaline earth metal thioindates of MIn/sub 2/S/sub 4/ composition were synthesized by interaction of alkaline earth metal oxoindates with hydrogen sulfide during heating. Investigation into the compounds by X-ray analysis showed that calcium compound crystallizes in cubic crystal system and strontium and barium compounds in rhombic crystal system. Lattice parameters and the number of formula units were determined. Thioindates of M/sub 3/In/sub 2/S/sub 6/ composition were synthesized, their individuality was shown.

  18. Rare (Earth Elements [score

    Directory of Open Access Journals (Sweden)

    Camilo Méndez

    2014-12-01

    Full Text Available Rare (Earth Elements is a cycle of works for solo piano. The cycle was inspired by James Dillon’s Book of Elements (Vol. I-V. The complete cycle will consist of 14 pieces; one for each selected rare (earth element. The chosen elements are Neodymium, Erbium, Tellurium, Hafnium, Tantalum, Technetium, Indium, Dysprosium, Lanthanium, Cerium, Europium, Terbium, Yttrium and Darmstadtium. These elements were selected due to their special atomic properties that in many cases make them extremely valuable for the development of new technologies, and also because of their scarcity. To date, only 4 works have been completed Yttrium, Technetium, Indium and Tellurium.

  19. Teaching earth science

    Science.gov (United States)

    Alpha, Tau Rho; Diggles, M.F.

    1998-01-01

    This CD-ROM contains 17 teaching tools: 16 interactive HyperCard 'stacks' and a printable model. They are separated into the following categories: Geologic Processes, Earthquakes and Faulting, and Map Projections and Globes. A 'navigation' stack, Earth Science, is provided as a 'launching' place from which to access all of the other stacks. You can also open the HyperCard Stacks folder and launch any of the 16 stacks yourself. In addition, a 17th tool, Earth and Tectonic Globes, is provided as a printable document. Each of the tools can be copied onto a 1.4-MB floppy disk and distributed freely.

  20. Quantizing Earth surface deformations

    Directory of Open Access Journals (Sweden)

    C. O. Bowin

    2015-03-01

    Full Text Available The global analysis of Bowin (2010 used the global 14 absolute Euler pole set (62 Myr history from Gripp and Gordon (1990 and demonstrated that plate tectonics conserves angular momentum. We herein extend that analysis using the more detailed Bird (2003 52 present-day Euler pole set (relative to a fixed Pacific plate for the Earth's surface, after conversion to absolute Euler poles. Additionally, new analytical results now provide new details on upper mantle mass anomalies in the outer 200 km of the Earth, as well as an initial quantizing of surface deformations.

  1. IR and the Earth

    DEFF Research Database (Denmark)

    Corry, Olaf; Stevenson, Hayley

    2017-01-01

    , in the end, one finite interconnected space. Together these two starting points make for the basic conundrum of Inter- national Relations and the Earth: how does a divided world live on a single globe? This introduction first provides an overview of the recent rise of ‘the environment’ in international......, ‘what has the environment ever done for IR?’, before the plan for the rest of the book sketches the content and direction of the ensuing chapters that explore the problematique of International Relations and the Earth....

  2. 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.

  3. Environmentální výchova v předškolním vzdělávání – hledání optimální podoby

    Directory of Open Access Journals (Sweden)

    Kateřina Jančaříková

    2012-05-01

    Full Text Available Příspěvek navazuje na předchozí publikace obou autorek (Jančaříková, 2008, Kapuciánová, 2010 a je zaměřen na environmentální výchovu v MŠ. Jeho cílem je poskytnout učitelkám MŠ oporu při realizaci EVVO. Podnětem pro jeho vznik byly rozhovory s učitelkami z mateřských škol uskutečněné na přednáškách a seminářích. Učitelky na nich opakovaně upozorňovaly na nedostatek komplexně pojatých podkladů pro realizaci EVVO. Rešeršní část je věnována EV v MŠ v zahraničí i u nás; poukazuje na zjištěnou nedostatečnou pozornost výzkumných pracovníků environmentální výchově v předškolním věku (Davis, 2009 a zároveň popisuje jisté zlepšování situace v několika posledních letech. Výstupem zde prezentovaného kvalitativního šetření (využívajícího vybrané nástroje zakotvené teorie jsou navržená kritéria realizace a autoevaluace environmentální výchovy v předškolním vzdělávání v Česku. Tento materiál mohou učitelky okamžitě použít v praxi (úprava ŠVP PV, vytvoření nástroje evaluace, resp. autoevaluace. Může sloužit také jako východisko pro odbornou diskusi cílů, obsahu, podmínek vyučování, prostředků, metod i kompetencí učitelek (učitelů.

  4. 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.

  5. Monodisperse and hollow structured Y{sub 2}O{sub 3}:Ln{sup 3+} (Ln = Eu, Dy, Er, Tm) nanospheres: A facile synthesis and multicolor-tunable luminescence properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ruiqing; Zi, Wenwen; Li, Linlin; Liu, Lu; Zhang, Junjun [College of Chemistry, Jilin University, Changchun 130026 (China); Zou, Lianchun, E-mail: zoulianchun@126.com [Teaching Center of Basic Courses, Jilin University, Changchun 130062 (China); Gan, Shucai, E-mail: gansc@jlu.edu.cn [College of Chemistry, Jilin University, Changchun 130026 (China)

    2014-12-25

    Highlights: • We reported a simple route to synthesize the Y{sub 2}O{sub 3} HNSs. • A possible formation mechanism of the Y{sub 2}O{sub 3} HNSs was proposed. • The Ln-doped Y{sub 2}O{sub 3} HNSs exhibit characteristic emission with different colors. • White-light-emitting phosphor Y{sub 2}O{sub 3}:Tm{sup 3+}, Dy{sup 3+} was also successfully synthesized. - Abstract: A novel, fast and simple method was developed to synthesize the undoped and lanthanide-doped yttrium oxide hollow nanospheres (Y{sub 2}O{sub 3}⋅HNSs) with multicolored downconversion emission under mild conditions by employing poly (acrylic acid sodium salt) microspheres (PAAS MSs) as active templates followed by a subsequent calcination process. The structure, morphology, formation process, and fluorescent properties are well investigated using various techniques. The results show that the samples can be well indexed to the pure cubic phase of Y{sub 2}O{sub 3}. The possible formation mechanism of the PAAS MSs, PAA-Y precursor, and Y{sub 2}O{sub 3} HNSs are proposed and discussed in detail. Upon ultraviolet excitation, the obtained Y{sub 2}O{sub 3}:Ln{sup 3+} (Ln = Eu, Dy, Er, Tm) HNSs exhibit strong red, yellow–green, blue, yellow emission, respectively. Moreover, a novel single-phased and near-UV-pumped white-light-emitting phosphor Y{sub 2}O{sub 3}:Tm{sup 3+}, Dy{sup 3+} was also successfully fabricated through optimizing the molar ratio among Tm{sup 3+} and Dy{sup 3+} in the Y{sub 2}O{sub 3} host. This material may find potential applications in field-emission display devices and white ultraviolet light-emitting diodes (UV LEDs). Furthermore, this synthesis route may be of great significance in the preparation of other hollow spherical materials.

  6. Préparation et caractérisation d'une série de cyclohexaphosphates de terres rares: Ln2P 6O 18 · 10H 2O

    Science.gov (United States)

    Elmokhtar, Ould Sidi Mohamed; Rzaigui, Mohamed

    1995-10-01

    Six new cyclohexaphosphates with the general formula Ln2 P 6O 18 · 10H 2O with Ln = La, Ce, Pr, Sm, Er, and Yb are reported. They belong to two different structure types. The first type, common to three compounds, corresponds to Ln = La, Ce, and Pr, with an orthorhombic unit cell, Z = 2, and space group P2 12 12. The second type, common to three compounds also, corresponds to Ln = Sm, Er, and Yb, with a monoclinic unit cell, Z = 4, and space group P2 1/ a. Synthesis and characterization by X-ray diffraction, IR absorption, and TA are given.

  7. Luminescence spectroscopy of rare earth-doped oxychloride lead borate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Pisarski, Wojciech A., E-mail: Wojciech.Pisarski@us.edu.p [University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice (Poland); Pisarska, Joanna [University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice (Poland); Lisiecki, RadosLaw [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okolna 2, 50-422 WrocLaw (Poland); Grobelny, Lukasz [University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice (Poland); Dominiak-Dzik, Grazyna; Ryba-Romanowski, Witold [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okolna 2, 50-422 WrocLaw (Poland)

    2011-04-15

    Ln-doped oxychloride lead borate glasses were studied using luminescence spectroscopy. Rare earth ions were limited to trivalent Pr{sup 3+}, Tm{sup 3+}, Eu{sup 3+} and Er{sup 3+}. Luminescence spectra were registered, which correspond to {sup 3}P{sub 0}-{sup 3}H{sub 4} and {sup 1}D{sub 2}-{sup 3}H{sub 4} transitions of Pr{sup 3+}, {sup 1}G{sub 4}-{sup 3}H{sub 5} and {sup 1}G{sub 4}-{sup 3}F{sub 4} transitions of Tm{sup 3+}, {sup 5}D{sub 0}-{sup 7}F{sub J} (J=0, 1, 2, 3, 4) transitions of Eu{sup 3+} and {sup 4}S{sub 3/2},{sup 2}H{sub 11/2}-{sup 4}I{sub 15/2} and {sup 4}I{sub 13/2}-{sup 4}I{sub 15/2} transitions of Er{sup 3+}. Luminescence decays from the excited states of Ln{sup 3+} ions were analyzed in detail. The experimental results indicate that relatively high phonon energy of the host gives important contribution to the excited state relaxation of rare earth ions. - Research Highlights: {yields}Lead borate glasses modified by PbCl{sub 2} were synthesized. {yields}Luminescence of Pr{sup 3+}, Tm{sup 3+}, Eu{sup 3+} and Er{sup 3+} ions in multicomponent oxychloride glasses was registered. {yields}From decay curves luminescence lifetimes for the excited states of rare earth ions were determined. {yields}The relatively high phonon energy of the host gives important contribution to the excited state relaxation of rare earth ions.

  8. Liquid-liquid reductive extraction in molten fluoride salt/liquid aluminium as a core of process for the An/Ln group separation

    Energy Technology Data Exchange (ETDEWEB)

    Conocar, O

    2007-06-15

    This report concerns a pyrochemical process based on liquid-liquid extraction in a molten fluoride/liquid aluminium system as a core process for actinide (An)/lanthanide (Ln) group separation, studied at CEA. The basic and demonstrative experiments have established the feasibility of the An/Ln group separation in the molten fluoride/liquid aluminium system (U, Pu, Np, Am, Cm traces from Nd, Ce, Eu, Sm, Eu, La - An/Ln separation factors over 1000 - An recovery yield over 98 % in one batch). The main experimental efforts must now be targeted on the recovery of actinides from the Al matrix. A thermodynamic and bibliographical survey has been done. It shows that back-extraction in a molten chloride melt could be a promising technique for this purpose.

  9. Syntheses, crystal structures and properties of series of 4d–4f ln(III)–Ag(I) heterometallic coordination polymers

    Energy Technology Data Exchange (ETDEWEB)

    Ran, Xing-Rui [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Wang, Ning [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Xie, Wei-Ping; Xiong, Yan-Ju; Cheng, Qian [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Long, Yi [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Yue, Shan-Tang, E-mail: yuesht@scnu.edu.cn [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Guangzhou Key Laboratory of Materials for Energy Conversion and Storage, Guangzhou (China); Liu, Ying-Liang [College of Science, South China Agricultural University, Guangzhou 510642 (China)

    2015-05-15

    By control of the experimental parameters such as ligands, pH value and reacting temperature, series of three-dimensional (3D) 4d–4f Ln(III)–Ag(I) porous coordination polymers (PCPs) with interesting chain-layer construction, namely, ([Ln{sup III}Ag{sup I}(na)(ina)(ox)]·2(H{sub 2}O)){sub n} [Ln=Sm(1), Eu(2), Gd(3), Tb(4), Dy(5), Ho(6), Y(7), Yb(8)], have been successfully synthesized under hydrothermal conditions and structurally characterized. All the complexes are characterized by elemental analyses, FT-IR spectroscopy, Powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Furthermore, the luminescence properties of compounds 2 and 4 and the magsnetic properties of complexes 3 and 5 were also investigated in detail. - Graphical abstract: Series of three-dimensional (3D) 4d–4f Ln(III)–Ag(I) porous coordination polymers (PCPs) with interesting chain-layer construction which are featured by tetranuclear Ln{sub 2}Ag{sub 2} and ‘non-linear’ N–Ag–N linkages. - Highlights: • Complexes 1–8 are first built by three kinds of organic ligands based on nicotinic acid and isonicotinic acid. • PCPs 1–8 are featured by tetranuclear Ln{sub 2}Ag{sub 2} and ‘non-linear’ N–Ag–N linkages. • The total solvent-accessible volume of PCP 2 comprises 11.6% of the crystal volume after dislodging the free water molecules. • Complexes 2 and 4 exhibit characteristic lanthanide-centered luminescence, while compounds 3 and 5 show antiferromagnetic behaviors.

  10. Tridecanuclear [Mn(III)5Ln(III)8] complexes derived from N-(t)butyl-diethanolamine: synthesis, structures, and magnetic properties.

    Science.gov (United States)

    Ako, Ayuk M; Mereacre, Valeriu; Clérac, Rodolphe; Hewitt, Ian J; Lan, Yanhua; Buth, Gernot; Anson, Christopher E; Powell, Annie K

    2009-07-20

    The synthesis, structures and magnetic properties of a family of heterometallic [Mn(III)(5)Ln(III)(8)(mu(3)-OH)(12)(L(2))(4)(piv)(12)(NO(3))(4)(OAc)(4)](-) (Ln = Pr, 2; Nd, 3; Sm, 4; Gd, 5; Tb, 6) aggregates are reported. The complexes were obtained from the direct reaction of N-(t)butyldiethanolamine (H(2)L(2)) with Mn(OAc)(2) x 4 H(2)O and Ln(NO(3))(3) x 6 H(2)O in the presence of pivalic acid (pivH) in MeCN under ambient conditions. Compounds 2-6 are isomorphous and crystallize in the monoclinic space group P2(1)/n with four molecules in the unit cell. The complexes have a centrosymmetric tridecanuclear anionic core consisting of two distorted inner heterometallic [Mn(III)Ln(III)(3)(mu(3)-OH)(4)](8+) cubane subunits sharing a common Mn vertex flanked by four edge-sharing heterometallic [Mn(III)Ln(III)(2)(mu(3)-OH)(4)](5+) defect cubane units. Complexes 2-6 are the first high-nuclearity 3d-4f aggregates reported to date using (t)Bu-deaH(2) as ligand. These compounds show no evidence of slow relaxation behavior above 1.8 K, which appears to be the consequence of the very weak or non-existent magnetic interactions between the Mn(III) and Ln(III) ions resulting from the particular angles at the bridging oxygens.

  11. Bones of the Earth

    Science.gov (United States)

    Correa, Jose Miguel

    2014-01-01

    The film "Bones of the Earth" (Riglin, Cunninham & Correa, 2014) is an experience in collective inquiry and visual creation based on arts-based research. Starting from the meeting of different subjectivities and through dialogue, planning, shooting and editing, an audiovisual text that reconstructs a reflexive process of collective…

  12. Earth as art 4

    Science.gov (United States)

    ,

    2016-03-29

    Landsat 8 is the latest addition to the long-running series of Earth-observing satellites in the Landsat program that began in 1972. The images featured in this fourth installment of the Earth As Art collection were all acquired by Landsat 8. They show our planet’s diverse landscapes with remarkable clarity.Landsat satellites see the Earth as no human can. Not only do they acquire images from the vantage point of space, but their sensors record infrared as well as visible wavelengths of light. The resulting images often reveal “hidden” details of the Earth’s land surface, making them invaluable for scientific research.As with previous Earth As Art exhibits, these Landsat images were selected solely for their aesthetic appeal. Many of the images have been manipulated to enhance color variations or details. They are not intended for scientific interpretation—only for your viewing pleasure. What do you see in these unique glimpses of the Earth’s continents, islands, and coastlines?

  13. DIORAMA Earth Terrain Model

    Energy Technology Data Exchange (ETDEWEB)

    Werley, Kenneth Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-10

    When simulating near-surface nuclear detonations, the terrain of the Earth can have an effect on the observed outputs. The critical parameter is called the “height of burst”. In order to model the effect of terrain on the simulations we have incorporated data from multiple sources to give 9 km resolution data with global coverage.

  14. 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...

  15. Google Earth Science

    Science.gov (United States)

    Baird, William H.; Padgett, Clifford W.; Secrest, Jeffery A.

    2015-01-01

    Google Earth has made a wealth of aerial imagery available online at no cost to users. We examine some of the potential uses of that data in illustrating basic physics and astronomy, such as finding the local magnetic declination, using landmarks such as the Washington Monument and Luxor Obelisk as gnomons, and showing how airport runways get…

  16. Understanding Earth's Albedo Effect

    Science.gov (United States)

    Fidler, Chuck

    2012-01-01

    Earth and space science in the middle school classroom are composed of intricately intertwined sets of conceptual systems (AAAS 1993; NRC 1996). Some systems of study, such as the water and rock cycles, are quite explicit and often found as stand-alone middle school science units. Other phenomena are not so apparent, yet they play an extremely…

  17. Olympus and Earth Day

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Let your gaze rest upon the poster for Earth Day on April 22. A small polar bear clings tightly to the stem of an aero-vane. Staring at the vanishing floating ice on the wild sea, his eyes are full of panic and fear.

  18. Google Earth Science

    Science.gov (United States)

    Baird, William H.; Padgett, Clifford W.; Secrest, Jeffery A.

    2015-01-01

    Google Earth has made a wealth of aerial imagery available online at no cost to users. We examine some of the potential uses of that data in illustrating basic physics and astronomy, such as finding the local magnetic declination, using landmarks such as the Washington Monument and Luxor Obelisk as gnomons, and showing how airport runways get…

  19. Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    @@ Rare earth market continued drop tendency.There was not much transaction of didymium oxide and the alloy. Affected by reduced order of NdFeB magnetic materials and inactive dealings of didymium mischmetal,price of didymium mischmetal had dropped from RMB ¥95,000~98,000/ton to RMBY 93,000~95,000/ton currently.

  20. Cosmic rays on earth

    Energy Technology Data Exchange (ETDEWEB)

    Allkofer, O.C.; Grieder, P.K.F.

    1984-01-01

    A data collection is presented that covers cosmic rays on earth. Included are all relevant data on flux and intensity measurements, energy spectra, and related data of all primary and secondary components of the cosmic radiation at all levels in the atmosphere, at sea level and underground. In those cases where no useful experimental data have been available, theoretical predictions were substituted.

  1. "Galileo Calling Earth..."

    Science.gov (United States)

    National Aeronautics and Space Administration, Washington, DC.

    This guide presents an activity for helping students understand how data from the Galileo spacecraft is sent to scientists on earth. Students are asked to learn about the concepts of bit-rate and resolution and apply them to the interpretation of images from the Galileo Orbiter. (WRM)

  2. Earth flyby anomalies

    Energy Technology Data Exchange (ETDEWEB)

    Nieto, Michael Martin [Los Alamos National Laboratory; Anderson, John D [PROPULSION LAB.

    2009-01-01

    In the planet-centric system, a spacecraft should have the same initial and final energies, even though its energy and angular momentum will change in the barycenter of the solar system. However, without explanation, a number of earth flybys have yielded small energy changes.

  3. Protect the Earth

    Institute of Scientific and Technical Information of China (English)

    张永兴

    2011-01-01

    The earth, a blue globe, is very beautiful. It is the home to all the living things. But the environment around us is becoming worse and worse. People cut down trees to build houses and throw about litter. The air pollution is almost everywhere in the world!

  4. Citizens of Planet Earth

    DEFF Research Database (Denmark)

    Frisk, Kristian

    2015-01-01

    The inability of the nation-state system to handle contemporary environmental issues comprehensively has spurred greater cooperation between religious and secular civil society actors. An empirical analysis of the Alliance of Religions and Conservation (ARC) contributes to knowledge about this pr...... (2010a) have termed Terrapolitan Earth Religion....

  5. Carrier behavior in the T sup * -phase of (Ln sub 1-x-y , Ln' sub x ,Sr sub y ) sub 2 CuO sub 4-. delta. [PrCeSrCuO; PrSmSrCuO; PrGdSrCuO; NdCeSrCuO; LaSmSrCuO; LaEuSrCuO; LaGdSrCuO

    Energy Technology Data Exchange (ETDEWEB)

    Ohashi, Naoki; Ikawa, Hiroyuki; Fukunaga, Osamu (Dept. of Inorganic Materials, Tokyo Inst. of Tech. (Japan)); Kobayashi, Michiko; Tanaka, Junzo (National Inst. for Research in Inorganic Materials, Ibaraki (Japan))

    1991-07-01

    The effects of substituting La ions by Sr ions and annealing in oxygen atmosphere on the conduction properties of the T{sup *}-phase of (Ln{sub 1-x-y},Ln'{sub x},Sr{sub y}){sub 2}CuO{sub 4-{delta}} were elucidated by measuring the Hall effect and by iodometric titration. Superconductivity appeared in compounds having a Hall coefficient of (eR{sub H}){sup -1}>0{sup 21} cm{sup -3}. Even when the average excess valence of Cu ions was the same, the carrier concentration, varied with the kind of lanthanide ions (Ln and Ln'). (orig.).

  6. Whole-Earth Decompression Dynamics

    CERN Document Server

    Herndon, J M

    2005-01-01

    The principles of Whole-Earth Decompression Dynamics are disclosed leading to a new way to interpret whole-Earth dynamics. Whole-Earth Decompression Dynamics incorporates elements of and unifies the two seemingly divergent dominant theories of continential displacement, plate tectonics theory and Earth expansion theory. Whole-Earth decompression is the consequence of Earth formation from within a Jupiter-like protoplanet with subsequent loss of gases and ices and concomitant rebounding. The initial whole-Earth decompression is expected to result in a global system of major primary decompression cracks appearing in the rigid crust which persist as the basalt feeders for the global, mid-oceanic ridge system. As the Earth subsequently decompresses, the area of the Earth's surface increases by the formation of secondary decompression cracks, often located near the continental margins, presently identified as oceanic trenches. These secondary decompression cracks are subsequently in-filled with basalt, extruded fr...

  7. N-valued logic system Ln based on the derived operator of Lukasiewicz implication operator%Lukasiewicz蕴涵算子的导出算子及其n值逻辑系统Ln

    Institute of Scientific and Technical Information of China (English)

    平静水

    2010-01-01

    讨论了剩余类蕴涵算子之一Lukasiewicz蕴涵算子的导出算子的三值系统L3和n值逻辑系统Ln(n>3),首先给出了L3的真值表,它是C2真值表的扩充,它也保持MP规则和正则性,接下来讨论了L3中的重言式(tautology)与IPC(intuitionistic propositional calculus)公理之间的关系以及L3的准重言式与C2的重言式之间的关系.最后考虑了Ln中的子代数及不同逻辑系统Ln中重言式的比较.

  8. Efficient, stable, tunable, and easy to synthesize, handle and recycle luminescent materials: [H2NMe2]3[Ln(III)(2,6-dipicolinolate)3] (Ln = Eu, Tb, or its solid solutions).

    Science.gov (United States)

    Mooibroek, Tiddo Jonathan; Gamez, Patrick; Pevec, Andrej; Kasunic, Marta; Kozlevcar, Bojan; Fu, Wen-Tian; Reedijk, Jan

    2010-07-28

    Three compounds with the general formulae [H(2)N(Me)(2)](3)[Ln(2,6-dpa)(3)] were prepared from cheap and readily available reactants. Microcrystalline compounds could be isolated in high yields (>80%) by a simple filtration, after only one hour reaction time in refluxing DMF. The Eu and Tb compounds have been structurally characterized by single crystal X-ray diffraction. The compounds have unusual high-absorption coefficients (>95%) and quantum efficiencies (approximately 70%). Furthermore, they are thermally stable up to 250 degrees C and appear to be UV and water tolerant. The emission colour of the final compound can be easily fine-tuned, by varying the Eu:Tb ratio during the preparation.

  9. Inorganic speciation of deep groundwater and its effect on the characteristics of rare earth elements: with aquifers in coal bearing masures in Renlou coal mine in the north of Anhui Province as example%深层地下水稀土元素无机形态及其对稀土特征的影响——以皖北任楼矿煤系含水层为例

    Institute of Scientific and Technical Information of China (English)

    孙林华; 桂和荣; 陈松

    2011-01-01

    Based on analysis of major ions and rare earth element (REEs) concentrations of groundwater in an aquifer of coal bearing measures in Renlou coal mine in the north of Anhui Province, the inorganic speciation of dissolved REEs have been modeled by using the program-Visual Minteq. The results show that the groundwater canbe subdivided into SO42- enriched and alkaline (CO32-or HCO3-) enriched water with Ph values lower and higher than8.20/8.36 respectively. The SO4 enriched water has relative lower total REE concentration than HCO3- enrichedwater, although they all show light REEs depletion after PAAS (Post Archean Average Shale) normalization. Theinorganic species of SO42- enriched waters include Ln3+ , LnCO3+, LnSO4+, Ln(CO3)2- and Ln(SO4)2- (Ln-REE),whereas Ln(CO3)2 and LnCO3+ are predominant in HCO3- enriched water, and the relative proportions of species areclosely related to Ph values and element types (e.g. LREEs and HREEs). The concentration of HCO3- is well correlated with ∑REE and NdSN/YbSN ratio, indicating that the total concentration and fractionation of REEs ofgroundwater probably has been affected by different proportions of different species (especially Ln(CO3)2-).%在对皖北任楼矿煤系含水层地下水常规离子和稀土元素组成分析的基础上,运用Visual Minteq 软件对溶解态稀土的无机形态进行了模拟。结果表明:煤系含水层地下水分为富SO42-和富HCO3-(或富CO32-)两类,二者pH值大致以8.20/8.36为界。富SO42-水具有相对富HCO3-水偏低的稀土总量,但二者在PAAS(后太古代平均页岩)标准化图解上均表现为轻稀土亏损的型式。富SO42-水中稀土无机形态包括Ln3+、LnCO3+、LnSO4+、Ln(CO3)2-和Ln(SO4)2-(Ln代表稀土元素),但富HCO3-水中以Ln(CO3)2-和LnCO3+为主,且各形态的相对含量与pH值和元素类型(如轻、重稀土)关系密切。HCO3-含量与地下水∑REE和NdSN/YbSN存在明显的相关性,表明不同含量的稀土元素无机形态(尤其是Ln

  10. The Earth's Biosphere

    Science.gov (United States)

    2002-01-01

    In the last five years, scientists have been able to monitor our changing planet in ways never before possible. The Sea-viewing Wide Field-of-View Sensor (SeaWiFS), aboard the OrbView-2 satellite, has given researchers an unprecedented view of the biological engine that drives life on Earth-the countless forms of plants that cover the land and fill the oceans. 'There is no question the Earth is changing. SeaWiFS has enabled us, for the first time, to monitor the biological consequences of that change-to see how the things we do, as well as natural variability, affect the Earth's ability to support life,' said Gene Carl Feldman, SeaWiFS project manager at NASA's Goddard Space Flight Center, Greenbelt, Md. SeaWiFS data, based on continuous daily global observations, have helped scientists make a more accurate assessment of the oceans' role in the global carbon cycle. The data provide a key parameter in a number of ecological and environmental studies as well as global climate-change modeling. The images of the Earth's changing land, ocean and atmosphere from SeaWiFS have documented many previously unrecognized phenomena. The image above shows the global biosphere from June 2002 measured by SeaWiFS. Data in the oceans is chlorophyll concentration, a measure of the amount of phytoplankton (microscopic plants) living in the ocean. On land SeaWiFS measures Normalized Difference Vegetation Index, an indication of the density of plant growth. For more information and images, read: SeaWiFS Sensor Marks Five Years Documenting Earth'S Dynamic Biosphere Image courtesy SeaWiFS project and copyright Orbimage.

  11. Dynamic chiral-at-metal stability of tetrakis(d/l-hfc)Ln(III) complexes capped with an alkali metal cation in solution.

    Science.gov (United States)

    Lin, Yiji; Zou, Fang; Wan, Shigang; Ouyang, Jie; Lin, Lirong; Zhang, Hui

    2012-06-14

    Chiral tetrakis(β-diketonate) Ln(III) complexes Δ-[NaLa(d-hfc)(4)(CH(3)CN)] (1) and Λ-[NaLa(l-hfc)(4) (CH(3)CN)] (2) (d/l-hfc(-) = 3-heptafluo-robutylryl-(+)/(-)-camphorate) are a pair of enantiomers and crystallize in the same Sohncke space group (P2(1)2(1)2(1)) with dodecahedral (DD) geometry. Typically positive and negative exciton splitting patterns around 320 nm were observed in the solid-state circular dichroism (CD) spectra of complexes 1 and 2, which indicate that their shell configurational chiralities are Δ and Λ, respectively. The apparent bisignate couplets in the solid-state CD spectra of [CsLn(d-hfc)(4)(H(2)O)] [Ln = La (3), Yb (5)] and [CsLn(l-hfc)(4)(H(2)O)] [Ln = La (4), Yb (6)] show that they are a pair of enantiomers and their absolute configurations are denoted Δ and Λ, respectively. The crystallographic data of 5 reveals that its coordination polyhedron is the square antiprism (SAP) geometry and it undergoes a phase transition from triclinic (α phase, P1) to monoclinic (β phase, C2) upon cooling. The difference between the two phases is brought about by the temperature dependent behaviour of the coordination water molecules, but this did not affect the configurational chirality of the Δ-SAP-[Yb(d-hfc)(4)](-) moiety. Furthermore, time-dependent CD, UV-vis and (19)F NMR were applied to study the solution behavior of these complexes. It was found that the chiral-at-metal stability of the three pairs of complexes is different and affected by both the Ln(3+) and M(+) ion size. The results show that the Cs(+) cation can retain the metal center chirality and stablize the structures of [Ln(d/l-hfc)(4)](-) or the dissociated tris(d/l-hfc)Ln(III) species in solution for a longer time than that of the Na(+) cation, and it is important that the Cs(+) ion successfully lock the configurational chirality around the Yb(3+) center of the complex species in solution. This is reasoned by the short Cs(+)···FC, Cs(+)···O-Yb and Cs(+)···Yb(3

  12. O($\\alpha\\alpha_{s}$ln m$_{t}$. sup(2)) non-universal corrections to the decay rate $\\Gamma$(Z --> b$\\overline{b}$)

    CERN Document Server

    Kwiatkowski, A; Kwiatkowski, A; Steinhauser, M

    1994-01-01

    The partial decay rate \\Gamma(Z\\to b\\bar{b}) is significantly influenced by the mass of the top quark due to electroweak radiative corrections. The leading \\sim m_t^2 and the next-to-leading contribution \\sim \\ln m_t^2 are known to be numerically of similar size. In this work we calculate the QCD corrections to the logarithmic correction using the heavy top mass expansion. The {\\cal O} (\\alpha\\as \\ln m_t^2) corrections are of the same order as the QCD corrections to the quadratic top mass term, but of different sign.

  13. 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.

  14. Syntheses and Crystal Structures of Two Cyano-bridged Bimetallic Complexes [Ln(DMSO)2(H2O)(μ-CN)4Fe(CN)2](Ln= Ce and Eu, DMSO= Dimethylsulfoxide) with Layered Structure

    Institute of Scientific and Technical Information of China (English)

    ZHAO Zhen-Qian; CAI Li-Zhen; CHEN Wen-Tong; GUO Guo-Cong; HUANG Jin-Shun

    2008-01-01

    Two new bimetallic cyano-bridged complexes [Ln(DMSO)2(H2O)(μ-CN)4Fe(CN)2] (Ln = Ce 1, Eu 2) have been prepared by the grinding reaction method and structurally characterized by X-ray single-crystal structure analysis. Crystallographic data for 1: C10H14CeFeN6O3S2, Mr = 526.36, monoclinic, P2/n, a = 7.852(4), b = 10.729(5), c = 11.181(5) (A), β = 96.992(8)°, V = 935.0(7) A3, Z = 2, Dc = 1.870 g/cm3, μ = 3.421 mm-1, F(000) = 512, R = 0.0363 and wR = 0.0971; and those for 2: C10H14EuFeN6O3S2, Mr = 538.20, monoclinic, P2/n, a = 7.739(5), b = 10.668(7), c = 11.008(7) A, β = 96.943(3)°, V = 902.1(11) A3, Z = 2, Dc = 1.981 g/cm3, μ= 4.499 mm-1, F(000) = 522, R = 0.0345 and wR = 0.0855. In each complex the lanthanide ion is seven-coordinated in a pentagonal bipyramidal arrangement, and the Fe(Ⅲ) ion is in a nearly regular octahedral environment. The title complexes can be described as two-dimensional (2-D) stair-like structures, which are further connected by hydrogen bonds to form three-dimensional (3-D) frameworks.

  15. Crystallization of Two Cyanide-bridged Bimetallic Complexes [LN(DMSO)2(H2O)3Co(CN)6]·H2O (LN = Pr or Nd, DMSO = Dimethylsulfoxide)

    Institute of Scientific and Technical Information of China (English)

    梁淑惠; 车云霞; 郑吉民

    2005-01-01

    Two diadochy cyanide-bridged bimetallic complexes [Pr(DMSO)2(H2O)3Co(CN)6] ·H2O 1 and [Nd(DMSO)2(H2O)3Co(CN)6]·H2O 2 have been synthesized, and their crystal structures were determined by single-crystal X-ray diffraction methods. Crystal data for 1: monoclinic, space group P21/c, a = 7.692(2), b = 30.791(10), c = 9.131(3) (A), β =100.645(5)o, V = 2125.4(11) (A)3, Z = 4, the final R = 0.0422 and Wr = 0.0904 for 3484 observed reflections with I > 2σ(I); and those for 2: monoclinic, space group P21/c, a = 7.692(3), b = 30.902(11), c = 9.152(3) (A), β = 100.665(5)o, V = 2137.8(13) (A)3, Z = 4, the final R = 0.0515 and wR = 0.0906 for 3268 observed reflections with I > 2σ(I). The LN atoms are linked to the Co atoms by cyanide bridging, forming a two-dimensional gridding structure. The LN3+ ions are both eight-coordinated by three cyano nitrogen and five oxygen atoms of two DMSO and three water molecules. The X-ray single-crystal structure analysis shows that the unbridged cyanide ligands between the closest layers interact with the coordinated water molecules through hydrogen bonds to connect the two layers. Therefore, the molecular structure is a 3D hydrogen-bonded network derived from LNCo chains.

  16. Crystal structures of [Ln(NO33(μ2-bpydo2], where Ln = Ce, Pr or Nd, and bpydo = 4,4′-bipyridine N,N′-dioxide: layered coordination networks containing 44 grids

    Directory of Open Access Journals (Sweden)

    Michael L. Stromyer

    2016-01-01

    Full Text Available Three isostructural coordination networks of Ce, Pr, and Nd nitrate with 4,4′-bipyridine N,N′-dioxide (bpydo are reported, namely poly[[tris(nitrato-κ2O,O′cerium(III]-bis(μ2-4,4′-bipyridine N,N′-dioxide-κ2N:N′], [Ce(NO33(C10H8N2O22], poly[[tris(nitrato-κ2O,O′praeseodymium(III]-bis(μ2-4,4′-bipyridine N,N′-dioxide-κ2N:N′], [Pr(NO33(C10H8N2O22], and poly[[tris(nitrato-κ2O,O′neodymium(III]-bis(μ2-4,4′-bipyridine N,N′-dioxide-κ2N:N′], [Nd(NO33(C10H8N2O22]. All three compounds are isostructural to the previously reported La analogue. The asymmetric unit of [Ln(NO33(μ2-bpydo2] contains one lanthanide cation, two bpydo ligands, and three nitrate anions. Both bpydo ligands act as end-to-end μ2-bridges and display nearly ideal cis and gauche conformations, respectively. The bpydo ligands link the ten-coordinate LnIII cations, forming interdigitating 44 grid-like layers extending parallel to (-101, where interdigitation of layers is promoted by C—H...O interactions between nitrate anions and bpydo ligands. The interdigitated layers are linked to sets of neighboring layers via further C—H...O and π–π interactions.

  17. Earth: A Ringed Planet?

    Science.gov (United States)

    Hancock, L. O.; Povenmire, H.

    2010-12-01

    Among the most beautiful findings of the Space Age have been the discoveries of planetary rings. Not only Saturn but also Jupiter, Uranus and Neptune have rings; Saturn’s ring system has structures newly discovered; even Saturn's moon Rhea itself has a ring. All these are apparently supplied by material from the planetary moons (Rhea's ring by Rhea itself). The question naturally arises, why should the Earth not have a ring, and on the other hand, if it does, why has it not been observed? No rings have yet been observed in the inner solar system, but after all, rings in the inner solar system might simply tend to be fainter and more transient than those of the outer solar system: the inner solar system is more affected by the solar wind, and the Sun’s perturbing gravitational influence is greater. J.A. O’Keefe first suggested (1980) that Earth might have a ring system of its own. An Earth ring could account for some climate events. O’Keefe remarked that formation or thickening of a ring system in Earth’s equatorial plane could drive glaciation by deepening the chill of the winter hemisphere. (It is very well established that volcanic dust is an effective agent for the extinction of sunlight; this factor can be overwhelmingly apparent in eclipse observations.) O’Keefe died in 2000 and the speculation was not pursued, but the idea of an Earth ring has a prima facie reasonableness that calls for its renewed consideration. The program of this note is to hypothesize that, as O’Keefe proposed: (a) an Earth ring system exists; (b) it affects Earth's weather and climate; (c) the tektite strewn fields comprise filaments of the ring fallen to Earth's surface on various occasions of disturbance by comets or asteroids. On this basis, and drawing on the world's weather records, together with the Twentieth Century Reanalysis by NCEP/CIRES covering the period 1870-2010 and the geology of the tektite strewn fields, we herein propose the hypothesized Earth ring

  18. Rotation and magnetism of Earth`s inner core

    Energy Technology Data Exchange (ETDEWEB)

    Glatzmaier, G.A. [Los Alamos National Lab., NM (United States); Roberts, P.H. [Univ. of California, Los Angeles, CA (United States)

    1996-12-13

    Three-dimensional numerical simulations of the geodynamo suggest that a super-rotation of Earth`s solid inner core relative to the mantle is maintained by magnetic coupling between the inner core and an eastward thermal wind in the fluid outer core. This mechanism, which is analogous to a synchronous motor, also plays a fundamental role in the generation of Earth`s magnetic field. 18 refs., 6 figs.

  19. Precipitation in AISI 316L(N) during creep tests at 550 and 600 deg. C up to 10 years

    Energy Technology Data Exchange (ETDEWEB)

    Padilha, A.F. [University of Sao Paulo , Department of Metallurgical and Materials Engineering, Av. Prof. Mello Moraes 2463, CEP 05508-900, Sao Paulo (Brazil); Escriba, D.M. [University of Sao Paulo , Department of Metallurgical and Materials Engineering, Av. Prof. Mello Moraes 2463, CEP 05508-900, Sao Paulo (Brazil); Materna-Morris, E. [Forschungszentrum Karlsruhe, Institut fuer Materialforschung I, P.O. Box 3640, 76021 Karlsruhe (Germany)]. E-mail: materna-morris@imf.fzk.de; Rieth, M. [Forschungszentrum Karlsruhe, Institut fuer Materialforschung I, P.O. Box 3640, 76021 Karlsruhe (Germany); Klimenkov, M. [Forschungszentrum Karlsruhe, Institut fuer Materialforschung I, P.O. Box 3640, 76021 Karlsruhe (Germany)

    2007-05-15

    The precipitation behaviour in the gauge lengths and in the heads of initially solution annealed type 316L(N) austenitic stainless steel specimens tested in creep at 550 and 600 deg. C for periods of up to 85 000 h has been studied using several metallographic techniques. Three phases were detected: M{sub 23}C{sub 6}, Laves, and sigma phase. The volume fraction of the precipitated sigma phase was significantly higher than that of carbides and the Laves phase. M{sub 23}C{sub 6} carbide precipitation occurred very rapidly and was followed by the sigma and Laves phases formation in the delta ferrite islands. Sigma and Laves phases precipitated at grain boundaries after longer times. Two different mechanisms of sigma phase precipitation have been proposed, one for delta ferrite decomposition and another for grain boundary precipitation. Small quantities of the Laves phase were detected in delta ferrite, at grain boundaries and inside the grains.

  20. Mikrokalorimetrická studie bakteriální degradace ropy a ropných produktů

    OpenAIRE

    Bola, Tomáš

    2016-01-01

    Tato bakalářská práce se zabývá studiem degradace nafty, jako jednoho z možných produktů ropy pomocí bakteriálních kmenů Pseudomonas Putida a Pseudomonas Chlororaphis. Tato práce je motivována prozkoumáním využitelnosti metody, která nebyla k těmto účelům prozatím používána – kalorimetrická analýza. Pomocí IČ spektrometrie (ATR), kalorimetrie a UV-VIS spektrometrie byla studována míra a charakter interakcí. Kalorimetrická analýza ukázala, že Pseudomonas Putida má větší schopnost degradability...

  1. Effect of irradiation on the steels 316L/LN type to 12 dpa at 400 °C

    Science.gov (United States)

    Bulanova, T.; Fedoseev, A.; Kalinin, G.; Rodchenkov, B.; Shamardin, V.

    2004-08-01

    The 316L type stainless steel is widely used as a structural material for the fission reactors internal structures (core, core supports, etc.) and for experimental irradiation facilities. The 316L(N)-IG type steel is proposed as a main structural material for the ITER reactor (first wall, blanket, vacuum vessel, cooling pipe lines). It is obvious that different steel grades should exhibit different reaction to neutron irradiation. The main objective of this work was to study of irradiation behaviour of three different commercial steels: AISI 316LN, AISI 316L (US grades) and 02X17H14M2 (Russian steel grade that is similar to 316L). Irradiation effect on the three commercial steels of 316L family to ˜12 dpa at the temperature ˜370-400 °C on the tensile properties, microstructure, swelling and susceptibility to SCC are described in the paper.

  2. Effect of irradiation on the steels 316L/LN type to 12 dpa at 400 deg. C

    Energy Technology Data Exchange (ETDEWEB)

    Bulanova, T. E-mail: fae@niiar.rukalinig@nikiet.ru; Fedoseev, A.; Kalinin, G.; Rodchenkov, B.; Shamardin, V

    2004-08-01

    The 316L type stainless steel is widely used as a structural material for the fission reactors internal structures (core, core supports, etc.) and for experimental irradiation facilities. The 316L(N)-IG type steel is proposed as a main structural material for the ITER reactor (first wall, blanket, vacuum vessel, cooling pipe lines). It is obvious that different steel grades should exhibit different reaction to neutron irradiation. The main objective of this work was to study of irradiation behaviour of three different commercial steels: AISI 316LN, AISI 316L (US grades) and 02X17H14M2 (Russian steel grade that is similar to 316L). Irradiation effect on the three commercial steels of 316L family to {approx}12 dpa at the temperature {approx}370-400 deg. C on the tensile properties, microstructure, swelling and susceptibility to SCC are described in the paper.

  3. Low-x contribution to the Bjorken sum rule within unified $ln^2x+$LO DGLAP approximation

    CERN Document Server

    Kotlorz, D

    2004-01-01

    The small-$x$ contributions to the Bjorken sum rule within unified picture $ln^2x+$LO DGLAP for different input parametrisations $g_1^{NS}(x,Q_0^2)$ are presented. Theoretical predictions for $\\int_{0}^{0.003} g_1^{NS}(x,Q^2=10) dx$ are compared with the SMC small-$x$ data. Rough estimation of the slope $\\lambda$, controlling the small-$x$ behaviour of $g_1^{NS}\\sim x^{-\\lambda}$ from the obtained results and SMC data is performed. The crucial role of the running coupling $\\alpha_s=\\alpha_s(Q^2/z)$ at low-$x$ is taken into account.

  4. Correlation between the Cyclic Stress Behavior and Microstructure in 316LN based on the Analysis of Hysteresis Loops

    Institute of Scientific and Technical Information of China (English)

    CHANG Bo; ZHANG Zheng

    2014-01-01

    Total strain controlled cyclic test was performed on 316LN under uniaxial loadings. Through the partitioning of hysteresis loops, the evolution of two components of cyclic flow stress, the internal and effective stresses, was reported. The former one determines the cyclic stress response. Based on the transmission electron microscopic (TEM) observation on specimens loaded with scheduled cycles, it is found that planar dislocation structures prevail during the entire cyclic process at low strain amplitude, while a remarkable dislocation rearrangement from planar structures to heterogeneous spatial distributions is companied by a cyclic softening behavior at high strain amplitude. The competition between the evolution of the intergranular and the intragranular components of the internal stress caused by the transition of slip mode induces the cyclic hardening and softening at high strain levels. The intergranular internal stress represents the most part of the internal stress at low strain level.

  5. Earth Science Multimedia Theater

    Science.gov (United States)

    Hasler, A. F.

    1998-01-01

    The presentation will begin with the latest 1998 NASA Earth Science Vision for the next 25 years. A compilation of the 10 days of animations of Hurricane Georges which were supplied daily on NASA to Network television will be shown. NASA's visualizations of Hurricane Bonnie which appeared in the Sept 7 1998 issue of TIME magazine. Highlights will be shown from the NASA hurricane visualization resource video tape that has been used repeatedly this season on network TV. Results will be presented from a new paper on automatic wind measurements in Hurricane Luis from 1 -min GOES images that will appear in the October BAMS. The visualizations are produced by the Goddard Visualization & Analysis Laboratory, and Scientific Visualization Studio, as well as other Goddard and NASA groups using NASA, NOAA, ESA, and NASDA Earth science datasets. Visualizations will be shown from the "Digital-HyperRes-Panorama" Earth Science ETheater'98 recently presented in Tokyo, Paris and Phoenix. The presentation in Paris used a SGI/CRAY Onyx Infinite Reality Super Graphics Workstation at 2560 X 1024 resolution with dual synchronized video Epson 71 00 projectors on a 20ft wide screen. Earth Science Electronic Theater '999 is being prepared for a December 1 st showing at NASA HQ in Washington and January presentation at the AMS meetings in Dallas. The 1999 version of the Etheater will be triple wide with at resolution of 3840 X 1024 on a 60 ft wide screen. Visualizations will also be featured from the new Earth Today Exhibit which was opened by Vice President Gore on July 2, 1998 at the Smithsonian Air & Space Museum in Washington, as well as those presented for possible use at the American Museum of Natural History (NYC), Disney EPCOT, and other venues. New methods are demonstrated for visualizing, interpreting, comparing, organizing and analyzing immense Hyperimage remote sensing datasets and three dimensional numerical model results. We call the data from many new Earth sensing satellites

  6. Visualizing Earth Materials

    Science.gov (United States)

    Cashman, K. V.; Rust, A.; Stibbon, E.; Harris, R.

    2016-12-01

    Earth materials are fundamental to art. They are pigments, they are clay, they provide form and color. Earth scientists, however, rarely attempt to make the physical properties of Earth materials visible through art, and similarly many artists use Earth materials without fully understanding their physical and chemical properties. Here we explore the intersection between art and science through study of the physical properties of Earth materials as characterized in the laboratory, and as transferred to paper using different techniques and suspending media. One focus of this collaboration is volcanic ash. Ash is interesting scientifically because its form provides information on the fundamental processes that drive volcanic eruptions, and determines its transport properties, and thus its potential to affect populations far downwind of the volcano. Ash properties also affect its behavior as an art material. From an aesthetic point of view, ash lends a granular surface to the image; it is also uncontrollable, and thus requires engagement between artist and medium. More fundamentally, using ash in art creates an exchange between the medium and the subject matter, and imparts something of the physical, visceral experience of volcanic landscapes to the viewer. Another component of this work uses powdered rock as a printing medium for geologic maps. Because different types of rock create powders with different properties (grain size distributions and shapes), the geology is communicated not only as color, but also by the physical characteristics of the material as it interacts with the paper. More importantly, the use of actual rocks samples as printing material for geologic maps not only makes a direct connection between the map and the material it represents, but also provides an emotional connection between the map, the viewer and the landscape, its colors, textures and geological juxtapositions. Both case studies provide examples not only of ways in which artists can

  7. Towards earth AntineutRino TomograpHy (EARTH)

    NARCIS (Netherlands)

    De Meijer, R. J.; Smit, F. D.; Brooks, F. D.; Fearick, R. W.; Wortche, H. J.; Mantovani, F.

    2006-01-01

    The programme Earth AntineutRino TomograpHy (EARTH) proposes to build ten underground facilities each hosting a telescope. Each telescope consists of many detector modules, to map the radiogenic heat sources deep in the interior of the Earth by utilising direction sensitive geoneutrino detection.

  8. Prostor mezi environmentálním uměním a výchovou

    Directory of Open Access Journals (Sweden)

    Ondřej Navrátil

    2012-09-01

    Full Text Available Již od 60. a 70. let 20 století se dotýká environmentální problematika i prostoru umění, přičemž v posledních dvaceti letech můžeme hovořit o důsledné tematizaci v rámci tzv. environmentálního umění nebo eco artu. Článek zmiňuje a na příkladech prezentuje některé cíle a prostředky tohoto umění a srovnává je s oblastmi klíčových kompetencí EVVO. Nalézá mezi nimi shody a prostor, který je širší a rozmanitější, než se může jevit z úhlu tradičních pohledů. Tyto charakteristiky mohou být inspirativní především pro výtvarnou výchovu, jejíž aparát vyjadřovacích prostředků je do značné míry odvozován od uměleckých strategií.

  9. Functional PEG-PAMAM-tetraphosphonate capped NaLnF₄ nanoparticles and their colloidal stability in phosphate buffer.

    Science.gov (United States)

    Zhao, Guangyao; Tong, Lemuel; Cao, Pengpeng; Nitz, Mark; Winnik, Mitchell A

    2014-06-17

    Developing surface coatings for NaLnF4 nanoparticles (NPs) that provide long-term stability in solutions containing competitive ions such as phosphate remains challenging. An amine-functional polyamidoamine tetraphosphonate (NH2-PAMAM-4P) as a multidentate ligand for these NPs has been synthesized and characterized as a ligand for the surface of NaGdF4 and NaTbF4 nanoparticles. A two-step ligand exchange protocol was developed for introduction of the NH2-PAMAM-4P ligand on oleate-capped NaLnF4 NPs. The NPs were first treated with methoxy-poly(ethylene glycol)-monophosphoric acid (M(n) = 750) in tetrahydrofuran. The mPEG750-OPO3-capped NPs were stable colloidal solutions in water, where they could be ligand-exchanged with NH2-PAMAM-4P. The surface amine groups on the NPs were available for derivatization to attach methoxy-PEG (M(n) = 2000) and biotin-terminated PEG (M(n) = 2000) chains. The surface coverage of ligands on the NPs was examined by thermal gravimetric analysis, and by a HABA analysis for biotin-containing NPs. Colloidal stability of the NPs was examined by dynamic light scattering. NaGdF4 and NaTbF4 NPs capped with mPEG2000-PAMAM-4P showed colloidal stability in DI water and in phosphate buffer (10 mM, pH 7.4). A direct comparison with NaTbF4 NPs capped with a mPEG2000-lysine-based tetradentate ligand that we reported previously (Langmuir 2012, 28, 12861-12870) showed that both ligands provided long-term stability in phosphate buffer, but that the lysine-based ligand provided better stability in phosphate-buffered saline.

  10. 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.

  11. Complexations of Ln(III) with SnS{sub 4}H and Sn{sub 2}S{sub 6}: Solvothermal syntheses and characterizations of lanthanide coordination polymers with thiostannate and polyamine mixed ligands

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Chunying; Lu, Jialin; Han, Jingyu; Liu, Yun; Shen, Yali; Jia, Dingxian, E-mail: jiadingxian@suda.edu.cn

    2015-10-15

    Polymeric lanthanide complexes with thiostannate and polyamine mixed ligands, [Ln(peha)(μ–SnS{sub 4}H)]{sub n} [Ln=La (1a), Nd (1b)] and [(Ln(tepa)(μ–OH)){sub 2}(μ–Sn{sub 2}S{sub 6})]{sub n}nH{sub 2}O [Ln=Nd (2a), Sm (2b), Gd (2c), Dy (2d)] (peha=pentaethylenehexamine, tepa=tetraethylenepentamine) were respectively prepared in peha and tepa coordinative solvents by the solvothermal methods. In 1a and 1b, the Ln{sup 3+} ions are coordinated by a hexadentate peha ligand forming [Ln(peha)]{sup 3+} units. The [SnS{sub 4}H]{sup 3−} anion chelates a [Ln(peha)]{sup 3+} unit via two S atoms and coordinates to another [Ln(peha)]{sup 3+} unit via the third S atom. As a result, the [Ln(peha)]{sup 3+} units are connected into coordination polymers [Ln(peha)(μ–SnS{sub 4}H)]{sub n} by an unprecedented tridentate μ–η{sup 1},η{sup 2}–SnS{sub 4}H bridging ligands. In 2a–2d, the Ln{sup 3+} ions are coordinated by a pentadentate tepa ligand, and two [Ln(tepa)]{sup 3+} units are joined by two μ–OH bridges to form a binuclear [(Ln(tepa)(μ–OH)){sub 2}]{sup 4+} unit. Behaving as a bidentate μ–η{sup 1}, η{sup 1}–Sn{sub 2}S{sub 6} bridging ligand, the Sn{sub 2}S{sub 6} unit connects [(Ln(tepa)(μ–OH)){sub 2}]{sup 4+} units into a neutral coordination polymer [(Ln(tepa)(μ–OH)){sub 2}(μ–Sn{sub 2}S{sub 6})]{sub n} via the trans S atoms. The Ln{sup 3+} ions are in distorted monocapped square antiprismatic and bicapped trigonal prismatic environments in [(Ln(peha)(μ–SnS{sub 4}H)]{sub n} and [(Ln(tepa)(μ–OH)){sub 2}(μ–Sn{sub 2}S{sub 6})]{sub n}, respectively. The denticities of ethylene polyamine play an important role on the formation and complexation of the thiostannate in the presence of lanthanide ions. Compounds 1a–2d show well-defined absorption edges with band gaps between 2.81 and 3.15 eV. - Graphical abstract: Lanthanide coordination polymers concerning thiostannate ligands were prepared by the solvothermal methods, and μ{sub 3}

  12. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ February, 2010 Rare earth separation plants and downstream producers like NdFeB magnetic materials and phosphor materials successively ceased production due to Spring Festival, Chinese New Year. Transactions in rare earth market were few affected by public holidays.

  13. Mirador - Earth Surface and Interior

    Data.gov (United States)

    National Aeronautics and Space Administration — Earth Science data access made simple. The goal of the Earth Surface and Interior focus area is to assess, mitigate and forecast the natural hazards that affect...

  14. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ Active demands from downstream industry drove the price rise of rare earth products in Chinese domestic marketrecently, particularly didymium and dysprosium products. Prices of other rare earth products remained stable.

  15. China rare earth market review

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Rare earth market fluctuated slightly recently and the transactions remained sluggish. Environment control was strengthened in southern China and many rare earth plants had gone out of production. Some traders were considering selling commodities at low p

  16. NASA Benefits Earth

    Science.gov (United States)

    Robinson, Julie A.

    2009-01-01

    This slide presentation reviews several ways in which NASA research has benefited Earth and made life on Earth better. These innovations include: solar panels, recycled pavement, thermometer pill, invisible braces for straightening teeth, LASIK, aerodynamic helmets and tires for bicycles, cataract detection, technology that was used to remove Anthrax spores from mail handling facilities, study of atomic oxygen erosion of materials has informed the restoration of artwork, macroencapsulation (a potential mechanism to deliver anti cancer drugs to specific sites), and research on a salmonella vaccine. With research on the International Space Station just beginning, there will be opportunities for entrepreneurs and other government agencies to access space for their research and development. As well as NASA continuing its own research on human health and technology development.

  17. Life Before Earth

    CERN Document Server

    Sharov, Alexei A

    2013-01-01

    An extrapolation of the genetic complexity of organisms to earlier times suggests that life began before the Earth was formed. Life may have started from systems with single heritable elements that are functionally equivalent to a nucleotide. The genetic complexity, roughly measured by the number of non-redundant functional nucleotides, is expected to have grown exponentially due to several positive feedback factors: gene cooperation, duplication of genes with their subsequent specialization, and emergence of novel functional niches associated with existing genes. Linear regression of genetic complexity on a log scale extrapolated back to just one base pair suggests the time of the origin of life 9.7 billion years ago. This cosmic time scale for the evolution of life has important consequences: life took ca. 5 billion years to reach the complexity of bacteria; the environments in which life originated and evolved to the prokaryote stage may have been quite different from those envisaged on Earth; there was no...

  18. Heat-pipe Earth.

    Science.gov (United States)

    Moore, William B; Webb, A Alexander G

    2013-09-26

    The heat transport and lithospheric dynamics of early Earth are currently explained by plate tectonic and vertical tectonic models, but these do not offer a global synthesis consistent with the geologic record. Here we use numerical simulations and comparison with the geologic record to explore a heat-pipe model in which volcanism dominates surface heat transport. These simulations indicate that a cold and thick lithosphere developed as a result of frequent volcanic eruptions that advected surface materials downwards. Declining heat sources over time led to an abrupt transition to plate tectonics. Consistent with model predictions, the geologic record shows rapid volcanic resurfacing, contractional deformation, a low geothermal gradient across the bulk of the lithosphere and a rapid decrease in heat-pipe volcanism after initiation of plate tectonics. The heat-pipe Earth model therefore offers a coherent geodynamic framework in which to explore the evolution of our planet before the onset of plate tectonics.

  19. Testing MOND on Earth

    CERN Document Server

    Ignatiev, A Yu

    2014-01-01

    MOND is one of the most popular alternatives to Dark Matter (DM). While efforts to directly detect DM in laboratories have been steadily pursued over the years, the proposed Earth-based tests of MOND are still in their infancy. Some proposals recently appeared in the literature are briefly reviewed, and it is argued that collaborative efforts of theorists and experimenters are needed to move forward in this exciting new area. Possible future directions are outlined.

  20. Superhydrophobic diatomaceous earth

    Science.gov (United States)

    Simpson, John T [Clinton, TN; D& #x27; Urso, Brian R [Clinton, TN

    2012-07-10

    A superhydrophobic powder is prepared by coating diatomaceous earth (DE) with a hydrophobic coating on the particle surface such that the coating conforms to the topography of the DE particles. The hydrophobic coating can be a self assembly monolayer of a perfluorinated silane coupling agent. The DE is preferably natural-grade DE where organic impurities have been removed. The superhydrophobic powder can be applied as a suspension in a binder solution to a substrate to produce a superhydrophobic surface on the substrate.

  1. Why Earth aurorae shine?

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ By using the data obtained from three satellites of the Cluster mission launched by the European Space Agency (ESA), CAO Jinbin from the CAS Center for Space Science and Applied Research (CSSAR) and his US and European co-workers have clarified why Earth's aurorae shine.Their work entitled Joint Observations by Cluster Satellites of Bursty Bulk Flows in the Magnetotail was published in a recent issue of Journal of Geophysical Research.

  2. Life Before Earth

    OpenAIRE

    Sharov, Alexei A; Gordon, Richard

    2013-01-01

    An extrapolation of the genetic complexity of organisms to earlier times suggests that life began before the Earth was formed. Life may have started from systems with single heritable elements that are functionally equivalent to a nucleotide. The genetic complexity, roughly measured by the number of non-redundant functional nucleotides, is expected to have grown exponentially due to several positive feedback factors: gene cooperation, duplication of genes with their subsequent specialization,...

  3. Mission to Planet Earth

    Science.gov (United States)

    Tilford, Shelby G.; Wilson, Gregory S.; Backlund, Peter W.

    1991-01-01

    The NASA program described is an international study to predict changes in the earth's environment by means of multidisciplinary remote sensing from satellites. An international consortium dedicates satellites with advanced sensors to data collection, and a data processing system is described to collect and analyze a large amount of terrestrial data. The program requires international multidisciplinary involvement to collect and interpret the data and thereby manage and preserve the global environment.

  4. Earth Abides Arsenic Biotransformations

    OpenAIRE

    Zhu, Yong-Guan; Yoshinaga, Masafumi; Zhao, Fang-Jie; Rosen, Barry P.

    2014-01-01

    Arsenic is the most prevalent environmental toxic element and causes health problems throughout the world. The toxicity, mobility, and fate of arsenic in the environment are largely determined by its speciation, and arsenic speciation changes are driven, at least to some extent, by biological processes. In this article, biotransformation of arsenic is reviewed from the perspective of the formation of Earth and the evolution of life, and the connection between arsenic geochemistry and biology ...

  5. Earth before life

    OpenAIRE

    Marzban, Caren; Viswanathan, Raju; Yurtsever, Ulvi

    2014-01-01

    Background A recent study argued, based on data on functional genome size of major phyla, that there is evidence life may have originated significantly prior to the formation of the Earth. Results Here a more refined regression analysis is performed in which 1) measurement error is systematically taken into account, and 2) interval estimates (e.g., confidence or prediction intervals) are produced. It is shown that such models for which the interval estimate for the time origin of the genome i...

  6. Hunan Rare Earth Group Approved

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>Following Guangdong,Guangxi,Fujian and Jiangxi,Hunan announced that it would consolidate its rare earth resources-the consolidation plan of Hunan Rare Earth Group has been approved. Consolidation of the rare earth industry of south China is in full swing.According to "Several Opinions of the State Council on Promoting the Sustainable and Healthy Development of Rare Earth Industry"(hereinafter referred to as "Several Opinions")released in 2011,

  7. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    September 20-30, 2011 Rare earth market remained steady recently. Quoted prices of didymium products by separation and smelting plants kept stable. Some rare earth industrial zones in Baotou, Sichuan and Ganzhou had suspended production with the intensified environmental protection control and consolidation of rare earth industry. Persons in the industry hold a positive attitude toward the rare earth market after the National Day' s holiday in China. The market will develop healthily and orderly in the future.

  8. Characterising Super-Earths

    Directory of Open Access Journals (Sweden)

    Valencia D.

    2011-02-01

    Full Text Available The era of Super-Earths has formally begun with the detection of transiting low-mass exoplanets CoRoT-7b and GJ 1214b. In the path of characterising super-Earths, the first step is to infer their composition. While the discovery data for CoRoT-7b, in combination with the high atmospheric mass loss rate inferred from the high insolation, suggested that it was a rocky planet, the new proposed mass values have widened the possibilities. The combined mass range 1−10 M⊕ allows for a volatile-rich (and requires it if the mass is less than 4 M⊕ , an Earth-like or a super-Mercury-like composition. In contrast, the radius of GJ 1214b is too large to admit a solid composition, thus it necessarily to have a substantial gas layer. Some evidence suggests that within this gas layer H/He is a small but non-negligible component. These two planets are the first of many transiting low-mass exoplanets expected to be detected and they exemplify the limitations faced when inferring composition, which come from the degenerate character of the problem and the large error bars in the data.

  9. EARTH ROADS ARE EASY

    Directory of Open Access Journals (Sweden)

    David O. Whitten

    2000-01-01

    Full Text Available The earliest European immigrants in America traveled on waterways and on pathways worn into the earth by animals and Native Americans. Once their communities began to thrive, settlers widened paths and cleared new roads and streets then began experimenting with inexpensive surfacing to reduce dust in dry weather and mud in wet. “Earth Roads Are Easy” investigates materials and techniques used to maintain primitive thoroughfares with a minimum of effort and expense. The options range from the mundane—clay, sand, gravel, calcium chloride, oil, and tar—to the extraordinary—water glass, adobe clay, beet juice, and carpeting.There is no more dfficult problem confronting highway engineers than that of properly constructing and maintaining an earth road. The work may be less spectacular than the construction and maintenance of hard-surfaced roads, but there is greater latitude in location, methods of construction and choice of materials, consequently there is more scope for the exercise of sound judgment on the part of the engineer.1

  10. The Active Solid Earth

    Science.gov (United States)

    Ebinger, Cynthia

    2016-04-01

    Dynamic processes in Earth's crust, mantle and core shape Earth's surface and magnetic field over time scales of seconds to millennia, and even longer time scales as recorded in the ca. 4 Ga rock record. Our focus is the earthquake-volcano deformation cycles that occur over human time scales, and their comparison with time-averaged deformation studies, with emphasis on mantle plume provinces where magma and volatile release and vertical tectonics are readily detectable. Active deformation processes at continental and oceanic rift and back arc zones provide critical constraints on mantle dynamics, the role of fluids (volatiles, magma, water), and plate rheology. For example, recent studies of the East African rift zone, which formed above one of Earth's largest mantle upwellings reveal that magma production and volatile release rates are comparable to those of magmatic arcs, the archetypal zones of continental crustal creation. Finite-length faults achieve some plate deformation, but magma intrusion in the form of dikes accommodates extension in continental, back-arc, and oceanic rifts, and intrusion as sills causes permanent uplift that modulates the local time-space scales of earthquakes and volcanoes. Volatile release from magma intrusion may reduce fault friction and permeability, facilitating aseismic slip and creating magma pathways. We explore the implications of active deformation studies to models of the time-averaged structure of plume and extensional provinces in continental and oceanic plate settings.

  11. Earth System Monitoring, Introduction

    Science.gov (United States)

    Orcutt, John

    This section provides sensing and data collection methodologies, as well as an understanding of Earth's climate parameters and natural and man-made phenomena, to support a scientific assessment of the Earth system as a whole, and its response to natural and human-induced changes. The coverage ranges from climate change factors and extreme weather and fires to oil spill tracking and volcanic eruptions. This serves as a basis to enable improved prediction and response to climate change, weather, and natural hazards as well as dissemination of the data and conclusions. The data collection systems include satellite remote sensing, aerial surveys, and land- and ocean-based monitoring stations. Our objective in this treatise is to provide a significant portion of the scientific and engineering basis of Earth system monitoring and to provide this in 17 detailed articles or chapters written at a level for use by university students through practicing professionals. The reader is also directed to the closely related sections on Ecological Systems, Introduction and also Climate Change Modeling Methodology, Introduction as well as Climate Change Remediation, Introduction to. For ease of use by students, each article begins with a glossary of terms, while at an average length of 25 print pages each, sufficient detail is presented for use by professionals in government, universities, and industries. The chapters are individually summarized below.

  12. Afganistan and rare earths

    Directory of Open Access Journals (Sweden)

    Emilian M. Dobrescu

    2013-05-01

    Full Text Available On our planet, over a quarter of new technologies for the economic production of industrial goods, are using rare earths, which are also called critical minerals and industries that rely on these precious items being worth of an estimated nearly five trillion dollars, or 5 percent of world gross domestic product. In the near future, competition will increase for the control of rare earth minerals embedded in high-tech products. Rare minerals are in the twenty-first century what oil accounted for in the twentieth century and coal in the nineteenth century: the engine of a new industrial revolution. Future energy will be produced increasingly by more sophisticated technological equipment based not just on steel and concrete, but incorporating significant quantities of metals and rare earths. Widespread application of these technologies will result in an exponential increase in demand for such minerals, and what is worrying is that minerals of this type are almost nowhere to be found in Europe and in other industrialized countries in the world, such as U.S. and Japan, but only in some Asian countries, like China and Afghanistan.

  13. Sun, Earth and Sky

    CERN Document Server

    Lang, Kenneth R

    2006-01-01

    This Second Edition of Sun, Earth and Sky updates the popular text by providing comprehensive accounts of the most recent discoveries made by five modern solar spacecraft during the past decade. Their instruments have used sound waves to peer deep into the Sun’s inner regions and measure the temperature of its central nuclear reactor, and extended our gaze far from the visible Sun to record energetic outbursts that threaten Earth. Breakthrough observations with the underground Sudbury Neutrino Observatory are also included, which explain the new physics of ghostly neutrinos and solve the problematic mismatch between the predicted and observed amounts of solar neutrinos. This new edition of Sun, Earth and Sky also describes our recent understanding of how the Sun’s outer atmosphere is heated to a million degrees, and just where the Sun’s continuous winds come from. As humans we are more intimately linked with our life-sustaining Sun than with any other astronomical object, and the new edition therefore p...

  14. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ Supply of rare earth concentrate remained tight recently. Rare earth market exhibited rising tendency holistically Affected by tight supply of rare earth concentrate, many plants were operated under the capacity. Supply of didymium oxide got tighter and the price was on rising.

  15. Facile synthesis of NaYF4:Yb, Ln/NaYF4:Yb core/shell upconversion nanoparticles via successive ion layer adsorption and one-pot reaction technique

    NARCIS (Netherlands)

    Zeng, Q.; Xue, B.; Zhang, Y.; Wang, D.; Liu, X.; Tu, L.; Zhao, H.; Kong, X.; Zhang, H.

    2013-01-01

    The facile one-pot synthesis of NaYF4:Yb, Ln/NaYF4:Yb core/shell (CS) upconversion nanoparticles (UCNPs) was firstly developed through the successive ion layer adsorption and reaction (SILAR) technique, which represents an attractive alternative to conventional synthesis utilizing the chloride of Ln

  16. A family of 'windmill'-like {Cu6Ln12} complexes exhibiting single-molecule magnetism behavior and large magnetic entropy changes.

    Science.gov (United States)

    Alexandropoulos, Dimitris I; Poole, Katye M; Cunha-Silva, Luis; Ahmad Sheikh, Javeed; Wernsdorfer, Wolfgang; Christou, George; Stamatatos, Theocharis C

    2017-03-31

    A family of nanosized {Cu6Ln12} clusters with a 'windmill'-like topology was prepared from the employment of 2,6-diacetylpyridine dioxime, in conjunction with bridging N3(-), in 3d/4f-metal chemistry; the octadecanuclear compounds exhibit single-molecule magnetism behavior and large magnetic entropy changes, depending on the 4f-metal ion present.

  17. Colloidal Nanoparticles of Ln3+-Doped LaVO4: Energy Transfer to Visible- and Near-Infrared-Emitting Lanthanide Ions

    NARCIS (Netherlands)

    Stouwdam, Jan W.; Raudsepp, Mati; Veggel, van Frank C.J.M.

    2005-01-01

    Colloidal, organic solvent-soluble Ln3+-doped LaVO4 nanoparticles have been synthesized by a precipitation reaction in the presence of (C18H37O)2PS2- as ligand, that coordinates to the surface of the nanoparticles. The materials are well soluble in chlorinated solvent such as chloroform. Energy tran

  18. Hybrid luminescence materials assembled by [Ln(DPA)3]3- and mesoporous host through ion-pairing interactions with high quantum efficiencies and long lifetimes

    Science.gov (United States)

    Li, Qing-Feng; Yue, Dan; Lu, Wei; Zhang, Xinlei; Li, Chunyang; Wang, Zhenling

    2015-02-01

    A kind of mesoporous hybrid luminescence material was assembled through the ion exchange method between [Ln(DPA)3]3- and ionic liquid functionalized SBA-15. [Ln(DPA)3]3- was successfully anchored onto positive-charge modified SBA-15 by the strong electrostatic interaction. In [Ln(DPA)3]3-, Ln3+ ions are in 9-fold coordination through six oxygen atoms of carboxyl groups and three nitrogen atoms of pyridine units, leaving no coordination site for water molecules. Therefore the hybrids possess prominent luminescent properties, SBA-15-IMI-Tb(DPA)3 and SBA-15-IMI-Eu(DPA)3 exhibit high quantum yield values of 63% and 79%, and long lifetimes values of 2.38 ms and 2.34 ms, respectively. Especially, SBA-15-IMI-Eu(DPA)3 presents a high color purity, and the red/orange intensity ratio is as high as 7.6. The excellent luminescence properties and ordered mesoporous structures give rise to many potential applications in optical and electronic areas.

  19. Microstructure, local mechanical properties and stress corrosion cracking susceptibility of an SA508-52M-316LN safe-end dissimilar metal weld joint by GTAW

    Energy Technology Data Exchange (ETDEWEB)

    Ming, Hongliang; Zhu, Ruolin [Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning KeyLaboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049 (China); Zhang, Zhiming [Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning KeyLaboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wang, Jianqiu, E-mail: wangjianqiu@imr.ac.cn [Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning KeyLaboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Han, En.-Hou.; Ke, Wei [Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning KeyLaboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Su, Mingxing [Shanghai Research Center for Weld and Detection Engineering Technique of Nuclear Equipment, Shanghai 201306 (China)

    2016-07-04

    The microstructure, local mechanical properties and local stress corrosion cracking susceptibility of an SA508-52M-316LN domestic dissimilar metal welded safe-end joint used for AP1000 nuclear power plant prepared by automatic gas tungsten arc welding was studied in this work by optical microscopy, scanning electron microscopy (with electron back scattering diffraction and an energy dispersive X-ray spectroscopy system), micro-hardness testing, local mechanical tensile testing and local slow strain rate tests. The micro-hardness, local mechanical properties and stress corrosion cracking susceptibility across this dissimilar metal weld joint vary because of the complex microstructure across the fusion area and the dramatic chemical composition change across the fusion lines. Briefly, Type I boundaries and Type II boundaries exist in 52Mb near the SA508-52Mb interface, a microstructure transition was found in SA508 heat affected zone, the residual strain and grain boundary character distribution changes as a function of the distance from the fusion boundary in 316LN heat affected zone, micro-hardness distribution and local mechanical properties along the DMWJ are heterogeneous, and 52Mw-316LN interface has the highest SCC susceptibility in this DMWJ while 316LN base metal has the lowest one.

  20. Adaptivní filtry pro 2-D a 3-D zpracování digitálních obrazů

    OpenAIRE

    Martišek, Karel

    2012-01-01

    Práce se zabývá adaptivními filtry pro vizualizaci obrazů s vysokým rozlišením. V teoretické části je popsán princip činnosti konfokálního mikroskopu a matematicky korektně zaveden pojem digitální obraz. Pro zpracování obrazů je volen jak frekvenční přístup (s využitím 2-D a 3-D diskrétní Fourierovy transformace a frekvenčních filtrů), tak přístup pomocí digitální geometrie (s využitím adaptivní ekvalizace histogramu s adaptivním okolím). Dále jsou popsány potřebné úpravy pro práci s neideáln...