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Sample records for bronze sodium tungsten

  1. Acicular crystals of sodium tungsten bronzes

    Energy Technology Data Exchange (ETDEWEB)

    Bamberger, C.E. (Chemistry Div., Oak Ridge National Lab., Oak Ridge, TN (United States)); Kopp, O.C. (Chemistry Div., Oak Ridge National Lab., Oak Ridge, TN (United States) Dept. of Geological Sciences, Univ. of Tennessee, Knoxville, TN (United States))

    1993-08-01

    The synthesis of sodium tungsten bronzes, Na[sub x]WO[sub 3], with emphasis on crystals with acicular morphology, has been examined experimentally. The acicular morphology is obtained for a range of compositions in which 0.15 [<=] x [<=] 0.28, and generally more than one crystal structure is present. At x [approx] 0.28 the tetragonal II phase predominates, whereas at x [approx] 0.15 an unknown structure is the major phase. Surprisingly, all the bronzes tested exhibited large solubilities in hot aqueous solutions of NH[sub 4]OH. (orig.)

  2. Preparation and evaluation of thin-film sodium tungsten bronzes

    Science.gov (United States)

    Kautz, H. E.; Fielder, W. L.; Singer, J.; Fordyce, J. S.

    1974-01-01

    Thin films of sodium tungsten bronze (NaxWO3) were investigated as reversible sodium ion electrodes for solid electrolytes. The films were made by electron beam evaporation of the three phases, W metal, Na2WO4, and WO3, followed by sintering. The substrates were sodium beta alumina disks and glass slides. X-ray diffraction analyses of the films showed that sintering in dry nitrogen with prior exposure to air lead to mixed phases. Sintering in vacuum with no air exposure produced tetragonal I bronze with a nominal composition of Na0.31WO3, single phase within the limits of X-ray diffraction detectability. The films were uniform and adherent on sodium beta alumina substrates. The ac and dc conductivities of the beta alumina were measured with the sodium tungsten bronze films as electrodes. These experiments indicated that the tetragonal I bronze electrodes were not completely reversible. This may have resulted from sodium ion blocking within the bronze film or at the bronze beta alumina interface. Methods for attempting to make more completely reversible electrodes are suggested.

  3. Investigation into anodic dissolution of sodium-tungsten bronzes in tungstate melt

    International Nuclear Information System (INIS)

    Anodic dissolution of monocrystals of sodium-tungsten bronzes and tungsten in tungstate melts with different content of tungsten trioxide (20, 40, 60 mol%) is studied. It is shown that the dissolution of sodium-tungsten bronze at small current densities on the both electrodes proceeds reversibly in terms of identical chemical behaviour of cathode and anode processes and small polarization. As the current density increases, the process becomes complicated by the fact that alongside with the dissolution of bronzes their solid-phase oxidation takes place

  4. Investigation into anodic dissolution of sodium-tungsten bronzes in tungstate melt

    Energy Technology Data Exchange (ETDEWEB)

    Aksent' ev, A.G.; Kaliev, K.A.; Baraboshkin, A.N. (AN SSSR, Sverdlovsk. Inst. Ehlektrokhimii)

    1982-05-01

    Anodic dissolution of monocrystals of sodium-tungsten bronzes and tungsten in tungstate melts with different content of tungsten trioxide (20, 40, 60 mol%) is studied. It is shown that the dissolution of sodium-tungsten bronze at small current densities on both electrodes proceeds reversibly in terms of identical chemical behaviour of cathode and anode processes and small polarization. As the current density increases, the process becomes complicated by the fact that alongside with the dissolution of bronzes their solid-phase oxidation takes place.

  5. Microcrystalline sodium tungsten bronze nanowire bundles as efficient visible light-responsive photocatalysts.

    Science.gov (United States)

    Wang, Lei; Zhan, Jinhua; Fan, Weiliu; Cui, Guanwei; Sun, Honggang; Zhuo, Linhai; Zhao, Xian; Tang, Bo

    2010-12-14

    Microcrystalline sodium tungsten bronze nanowire bundles were obtained via a facile hydrothermal synthesis, and were applied in water purification as visible-light-driven photocatalysts for the first time. PMID:20953497

  6. Understanding metal–insulator transition in sodium tungsten bronze

    Indian Academy of Sciences (India)

    Sanhita Paul; Satyabrata Raj

    2015-06-01

    We have carried out angle-resolved photoemission spectroscopy (ARPES) and spectromicroscopy studies to understand the metal–insulator transition (MIT) observed in sodium tungsten bronzes, NaWO3. The experimentally determined band structure is compared with the theoretical calculation based on full-potential linear augmented plane-wave method. It has been found that there is a good gross agreement between experiment and theory. ARPES spectra on the insulating sample show that the states near F are localized due to the random distribution of Na in WO3 lattice which causes strong disorder in the system. Our spectromicroscopy measurements on both insulating and metallic samples do not approve percolation model to explain MIT in NaWO3. Photoemission spectroscopy on metallic samples does not show any Na-induced impurity band (level), which was one of the models to explain MIT. Electron-like Fermi surface(s) has been found from our experiment for metallic samples at the (X) point which shows good agreement with band calculation.

  7. Effect of lattice instability on superconductivity in sodium tungsten bronze

    International Nuclear Information System (INIS)

    The effect of lattice instability on the electronic properties of the tungsten bronzes, M/subx/WO3(0 3, the effect on the superconducting transition temperature of a phonon which is assumed to soften as a function of x is explicitly calculated. Tunneling between the local free-energy minima is assisted by this soft phonon. Good agreement is obtained with recent experimental observations of a dramatic increase in T/subc/ as x decreases and approaches the critical value for transition between the superconducting and semiconducting tetragonal phases. Noteworthy features of this work are that the structural transformation does not correspond to a simple condensation of the soft phonon, and also that the phonon softening and configurational tunneling are considered simultaneously

  8. Surface and electrocatalytic properties of tungsten bronzes

    International Nuclear Information System (INIS)

    Tafel plots have been obtained for the oxygen reaction in acid solution on several alkali tungsten bronzes having different crystal structures. Platinum doped sodium tungsten bronze crystals were studied and the results compared with those of platinum free crystals of the same composition. In both cases sodium tungsten bronzes were found to be poor electrocatalysts for the cathodic reduction of oxygen. Similar results are reported for other alkali tungsten bronzes and for tungsten trioxide. Anodic treatment of the crystals affected the electrocatalytic activity of only the sodium tungsten bronze and the effect was a negative one. Cyclic voltammetry was employed to study the effects of the anodic treatment which created a sodium depletion layer on the sodium tungsten bronze surface. The existence and depth of the sodium depletion layer was determined by an Auger Electron Spectroscopy depth profile

  9. Surface and electrocatalytic properties of tungsten bronzes

    Energy Technology Data Exchange (ETDEWEB)

    Weber, M.F.; Shanks, H.R.

    1977-01-01

    Tafel plots have been obtained for the oxygen reaction in acid solution on several alkali tungsten bronzes having different crystal structures. Platinum doped sodium tungsten bronze crystals were studied and the results compared with those of platinum free crystals of the same composition. In both cases sodium tungsten bronzes were found to be poor electrocatalysts for the cathodic reduction of oxygen. Similar results are reported for other alkali tungsten bronzes and for tungsten trioxide. Anodic treatment of the crystals affected the electrocatalytic activity of only the sodium tungsten bronze and the effect was a negative one. Cyclic voltammetry was employed to study the effects of the anodic treatment which created a sodium depletion layer on the sodium tungsten bronze surface. The existence and depth of the sodium depletion layer was determined by an Auger Electron Spectroscopy depth profile.

  10. Sodium tungsten bronze thin films by rf sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Anderegg, J.W.

    1977-03-01

    Polycrystalline Na/sub x/WO/sub 3/ films were produced by rf sputtering. Films of low x-value resulted when co-sputtering WO/sub 3/ on a Na/sub 0.83/WO/sub 3/ target, and Na/sub 0/./sub 83/ on WO/sub 3/ target. Films of high x and of mixed phase were produced by sputtering a powder mixture of Na/sub 2/WO/sub 4/ and WO/sub 3/ on a tungsten target. Of the sputtering parameters studied, the substrate temperature is the most critical with temperatures above 500/sup 0/C producing films which were cubic in structure with only a small amount of Tetragonal I. The presence of oxygen up to 3 percent by volume had minimal effect on film quality or x-value. Auger, electron microprobe, SIMS, SEM, x-ray diffraction, and sheet resistivity techniques were used in characterizing these films. Resistivity of the films was a factor of 10 higher than the bulk crystalline data for Na/sub 0/./sub 83/WO/sub 3/.

  11. Hollow Sodium Tungsten Bronze (Na0.15WO3) Nanospheres: Preparation, Characterization, and Their Adsorption Properties

    OpenAIRE

    Zuo Guanke; Guo He; Liu Hui; Zhang Jingyan; Hou Jing; Shen Guangxia; Cheng Ping; Guo Shouwu

    2009-01-01

    Abstract We report herein a facile method for the preparation of sodium tungsten bronzes hollow nanospheres using hydrogen gas bubbles as reactant for chemical reduction of tungstate to tungsten and as template for the formation of hollow nanospheres at the same time. The chemical composition and the crystalline state of the as-prepared hollow Na0.15WO3nanospheres were characterized complementarily, and the hollow structure formation mechanism was proposed. The hollow Na0.15WO3nanospheres sho...

  12. A green route for microwave synthesis of sodium tungsten bronzes NaxWO3 (0

    International Nuclear Information System (INIS)

    A green route has been developed for microwave synthesis of sodium tungsten bronzes NaxWO3 (02WO4, WO3 and tungsten powder. The hybrid microwave synthesis was carried out in argon atmosphere using CuO powder as the heating medium. Tungsten powder is used as the reducing agent instead of the alkali metal iodides previously used for the microwave synthesis of oxide bronzes. The prepared samples were characterized by powder X-ray diffraction, energy-dispersive X-ray analysis and scanning electron microscopy, and their phase constitutions, crystal structures and morphologies are in consistence with that in the literature. This synthesis method is simple, green and atom economic, and promising for preparation of other oxide bronzes and related compounds

  13. Computer simulation study of hexagonal tungsten oxide and its sodium bronzes

    International Nuclear Information System (INIS)

    The authors have used theoretical, computer based atomistic simulation techniques to investigate the transport properties of the sodium ions in hexagonal tungsten trioxide. Two approaches were taken. Firstly, using perfect lattice simulation methods, the hexagonal structure of WO/sub 3/ was modelled. The interatomic potentials were taken from an earlier study of crystallographic shear planes in WO/sub 3/. The results compared very well with the observed structure; the good agreement encouraged the authors to continue with a simulation of the sodium bronzes, using defeat lattic calculations. In the second approach, they investigated the behaviour of individual sodium ions and their interaction with the lattice, using defect energy calculations. The program used for this was CASCADE, a vectorized version of HADES III, implemented on the Cray-1 at the University of London. Insertion of Na+ to WO/sub 3/ requires the addition of an electron to the conduction band in order to maintain electroneutrality. The authors treated this electron as being localised on a tungsten cation, an assumption they feel is reasonable, given the semiconducting behavior found for Na/sub x/WO/sub 3/ at low values of x. They found that a single Na/sup +/ ion produced very little distortion of the surrounding lattice, a result that reflects the relative sizes of the ion and the tunnel and is, of course, a requirement for fast ion conduction

  14. Electrocatalytic activity and surface properties of tungsten bronzes

    International Nuclear Information System (INIS)

    The electrocatalytic activities of sodium tungsten bronzes, including high purity crystals, platinum doped crystals, and platinum plated crystals, have been measured for oxygen reduction in acid solution. In addition, a survey of the electrocatalytic activities and general electrochemical properties of other alkali tungsten bronzes, thalium tungsten bronze, and tungsten trioxide were investigated and compared to sodium tungsten bronze. All measurements were done on single crystals. Pure sodium tungsten bronzes and WO3 have a slight catalytic activity for oxygen reduction. The exchange current density is approximately 10-14 A/cm2. Doping the cubic sodium tungsten bronze with up to 800 ppM of platinum slightly increased the catalytic activity of the crystals, but the effect was noticeable only at very low current densities. Platinum preelectrolysis of the solution was shown to contaminate the crystal surface with significant amounts of platinum. For the platinum plated bronze crystals, no synergistic effect between the platinum and the bronze was observed for oxygen reduction. However, different platinum plating methods gave more than an order of magnitude difference in catalytic activity, with the same amount of platinum. The platinum was deposited on the bronze surface in different forms by the different plating methods. One possible form of highly dispersed platinum on a bronze surface is the formation of a platinum tungsten bronze, Pt/sub x/WO3. Hydrogen tungsten bronze is formed in the surface layers of all the bronzes at potentials below +0.2 V (NHE), and the reaction is completely reversible. One possible form of highly dispersed platinum on a bronze surface is the formation of a platinum tungsten bronze, Pt/sub x/WO3. Hydrogen tungsten bronze is formed in the surface layers of all the bronzes at potentials below +0.2 V (NHE), and the reaction is completely reversible

  15. Electrocatalytic activity and surface properties of tungsten bronzes

    Energy Technology Data Exchange (ETDEWEB)

    Weber, M.F.

    1977-12-01

    The electrocatalytic activities of sodium tungsten bronzes, including high purity crystals, platinum doped crystals, and platinum plated crystals, have been measured for oxygen reduction in acid solution. In addition, a survey of the electrocatalytic activities and general electrochemical properties of other alkali tungsten bronzes, thalium tungsten bronze, and tungsten trioxide were investigated and compared to sodium tungsten bronze. All measurements were done on single crystals. Pure sodium tungsten bronzes and WO/sub 3/ have a slight catalytic activity for oxygen reduction. The exchange current density is approximately 10/sup -14/ A/cm/sup 2/. Doping the cubic sodium tungsten bronze with up to 800 ppM of platinum slightly increased the catalytic activity of the crystals, but the effect was noticeable only at very low current densities. Platinum preelectrolysis of the solution was shown to contaminate the crystal surface with significant amounts of platinum. For the platinum plated bronze crystals, no synergistic effect between the platinum and the bronze was observed for oxygen reduction. However, different platinum plating methods gave more than an order of magnitude difference in catalytic activity, with the same amount of platinum. The platinum was deposited on the bronze surface in different forms by the different plating methods. One possible form of highly dispersed platinum on a bronze surface is the formation of a platinum tungsten bronze, Pt/sub x/WO/sub 3/. Hydrogen tungsten bronze is formed in the surface layers of all the bronzes at potentials below +0.2 V (NHE), and the reaction is completely reversible. One possible form of highly dispersed platinum on a bronze surface is the formation of a platinum tungsten bronze, Pt/sub x/WO/sub 3/. Hydrogen tungsten bronze is formed in the surface layers of all the bronzes at potentials below +0.2 V (NHE), and the reaction is completely reversible.

  16. High-energy electron-energy-loss study of sodium-tungsten bronzes

    International Nuclear Information System (INIS)

    Single-crystal metallic cubic sodium-tungsten bronzes NaxWO3 (x≥0.25) and NaxTayW1-yO3 (x-y=0.42) and monoclinic reduced WO3-δ have been investigated by high-energy electron-energy-loss spectroscopy (EELS) in transmission. For all electron densities the volume plasmon dispersion appears to be positive quadratic in momentum transfer q. The dispersion coefficient is much smaller than that predicted from the random-phase approximation for one isotropic parabolic band. This deviation can be reduced by recognizing the threefold degeneracy of the conduction-band t2g states in an octahedral field and narrowing of these bands with increasing sodium content. Anisotropy of the dispersion between the (100) and (110) direction is not observed. Optical effective masses m*(x) of the conduction electrons and background dielectric constants ε∞(x) have been determined and compare well with data from optical spectroscopy and EELS in reflection, but not with photoemission results. This discrepancy is a result of the photoemission-data evaluation in which the conduction-band degeneracy was neglected. Na 2p core-level excitation energies argue against an admixture of sodium orbitals to the conduction band near the metal-nonmetal transition at x∼0.2. Na 3s states admixed to O 2p states are observed at about 10--11 eV above the Fermi level in O 1s absorption edges. The x dependence of m* and of the width of the O 1s absorption edge of NaxWO3 supports a model of conduction-band narrowing with increasing Na concentration

  17. High-energy electron-energy-loss study of sodium-tungsten bronzes

    Energy Technology Data Exchange (ETDEWEB)

    Kielwein, M.; Saiki, K.; Roth, G. [Forschungszentrum Karlsruhe, Institut fuer Nukleare Festkoerperphysik, Postfach 3640, D-76021 Karlsruhe (Germany); Fink, J.; Paasch, G. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V., Institut fuer Festkoerperforschung, Postfach 270016, D-01171 Dresden (Germany); Egdell, R.G. [University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR (United Kingdom)

    1995-04-15

    Single-crystal metallic cubic sodium-tungsten bronzes Na{sub {ital x}}WO{sub 3} ({ital x}{ge}0.25) and Na{sub {ital x}}Ta{sub {ital y}}W{sub 1{minus}{ital y}}O{sub 3} ({ital x}{minus}{ital y}=0.42) and monoclinic reduced WO{sub 3{minus}{delta}} have been investigated by high-energy electron-energy-loss spectroscopy (EELS) in transmission. For all electron densities the volume plasmon dispersion appears to be positive quadratic in momentum transfer {ital q}. The dispersion coefficient is much smaller than that predicted from the random-phase approximation for one isotropic parabolic band. This deviation can be reduced by recognizing the threefold degeneracy of the conduction-band {ital t}{sub 2{ital g}} states in an octahedral field and narrowing of these bands with increasing sodium content. Anisotropy of the dispersion between the (100) and (110) direction is not observed. Optical effective masses {ital m}{sup *}({ital x}) of the conduction electrons and background dielectric constants {epsilon}{sub {infinity}}({ital x}) have been determined and compare well with data from optical spectroscopy and EELS in reflection, but not with photoemission results. This discrepancy is a result of the photoemission-data evaluation in which the conduction-band degeneracy was neglected. Na 2{ital p} core-level excitation energies argue against an admixture of sodium orbitals to the conduction band near the metal-nonmetal transition at {ital x}{similar_to}0.2. Na 3{ital s} states admixed to O 2{ital p} states are observed at about 10--11 eV above the Fermi level in O 1{ital s} absorption edges. The {ital x} dependence of {ital m}{sup *} and of the width of the O 1{ital s} absorption edge of Na{sub {ital x}}WO{sub 3} supports a model of conduction-band narrowing with increasing Na concentration.

  18. Domain structures of sodium tungsten bronzes, Na/sub x/WO/sub 3/ (0. 4 < x < 1)

    Energy Technology Data Exchange (ETDEWEB)

    Atoji, M.

    1978-01-01

    Optical-microscope observations with polarized light have shown that the birefringent, twin-domain structure of sodium tungsten bronzes is exhibited by Na-deficient, epitaxial surface films and hence is not a bulk property as had been suggested elsewhere. The film is translucent, 10/sup -2/ - 10/sup -3/ mm thick or less, and often laminates to a multi-film layer. The domain boundaries are sensitive to lateral stress and, apparently, to minute changes in the substrate structure. These and related properties of the film and the substrate are presented.

  19. Metal-insulator transition in sodium tungsten bronzes, NaxWO3, studied by angle-resolved photoemission spectroscopy

    International Nuclear Information System (INIS)

    We report high-resolution angle-resolved photoemission spectroscopy on sodium tungsten bronzes, NaxWO3, which exhibit a metal-insulator transition as a function of x. We found that the near-EF states are localized in NaxWO3 (x=+ ions in the WO3 lattice, which makes the system insulating. In the metallic regime we found that the rigid shift of band structure can explain the metallic NaxWO3 band structure with respect to Na doping

  20. Hollow Sodium Tungsten Bronze (Na0.15WO3 Nanospheres: Preparation, Characterization, and Their Adsorption Properties

    Directory of Open Access Journals (Sweden)

    Zuo Guanke

    2009-01-01

    Full Text Available Abstract We report herein a facile method for the preparation of sodium tungsten bronzes hollow nanospheres using hydrogen gas bubbles as reactant for chemical reduction of tungstate to tungsten and as template for the formation of hollow nanospheres at the same time. The chemical composition and the crystalline state of the as-prepared hollow Na0.15WO3nanospheres were characterized complementarily, and the hollow structure formation mechanism was proposed. The hollow Na0.15WO3nanospheres showed large Brunauer–Emment–Teller specific area (33.8 m2 g−1, strong resistance to acids, and excellent ability to remove organic molecules such as dye and proteins from aqueous solutions. These illustrate that the hollow nanospheres of Na0.15WO3should be a useful adsorbent.

  1. Hollow Sodium Tungsten Bronze (Na0.15WO3) Nanospheres: Preparation, Characterization, and Their Adsorption Properties.

    Science.gov (United States)

    Hou, Jing; Zuo, Guanke; Shen, Guangxia; Guo, He; Liu, Hui; Cheng, Ping; Zhang, Jingyan; Guo, Shouwu

    2009-01-01

    We report herein a facile method for the preparation of sodium tungsten bronzes hollow nanospheres using hydrogen gas bubbles as reactant for chemical reduction of tungstate to tungsten and as template for the formation of hollow nanospheres at the same time. The chemical composition and the crystalline state of the as-prepared hollow Na0.15WO3nanospheres were characterized complementarily, and the hollow structure formation mechanism was proposed. The hollow Na0.15WO3nanospheres showed large Brunauer-Emment-Teller specific area (33.8 m2 g-1), strong resistance to acids, and excellent ability to remove organic molecules such as dye and proteins from aqueous solutions. These illustrate that the hollow nanospheres of Na0.15WO3should be a useful adsorbent. PMID:20596394

  2. Domain and surface structures of sodium tungsten bronzes, Na/sub x/WO/sub 3/ (0. 4 < x < 1)

    Energy Technology Data Exchange (ETDEWEB)

    Atoji, M.

    1980-01-01

    Polarized-light microscopic observations have shown that the birefringent, twin-domain structure of metallic sodium tungsten bronze is exhibited by Na-deficient surface films and hence is not, as had been reported elsewhere, a bulk property. The film can be synthesized by anodic electrolysis in alkaline solution. It is chemically inert, translucent, and often laminates to a multiple layer. The domain structure of the film is hypersensitive to lateral stress and to thermal variation, exhibiting a marked change at the phase transition of the substrate through apparent epitaxial coherence. The domain-wall movement is often slow enough to be visible, and the thermally induced domain modulation is occasionally accompanied by audible high-pitched sound. The bulk structure of the substrate exhibits pseudoperiodic subboundaries that are probably caused by growth defects and the segregation of the sodium atoms. The near-surface of the substrate also shows the sodium segregation that tends to precipitate in periodic patterns. Optical and morphological properties of the substrate structures exhibited no detectable change due to thermal variation or external stress.

  3. Domain and surface structures of sodium tungsten bronzes, Na/sub x/WO/sub 3/ (0. 4 < x < 1). [157 references

    Energy Technology Data Exchange (ETDEWEB)

    Atoji, M.

    1978-09-01

    The domain and surface structures of metallic sodium tungsten bronzes, Na/sub x/WO/sub 3/, 0.4 < x < 1, were studied using optical microscopy, supplemented by chemical methods, photoelectron spectroscopy, electron microscopy, etc. The birefringent, multidomain structure of the bronze is exhibited by a sodium-deficient, epitaxial surface film and hence is not, as reported elsewhere, a bulk property. The film can be synthesized by anodic electrolysis in alkaline solution and can exist only epitaxially with the substrate. It is chemically inert, translucent, and often laminated to a multilayered film. The film domain is hypersensitive to lateral stress and to thermal change, and appears to be modulated by minute structural changes of the substrate. This epitaxial modulation of the film is strikingly large at the phase transitions of the substrate induced by slightly different tiltings of the oxygen octahedra. The domain-wall movement is often slow enough to be visible, and that by thermal effect is occasionally accompanied by an audible, high-pitched, snapping sound.

  4. Metal-insulator transition in sodium tungsten bronzes, Na{sub x}WO{sub 3}, studied by angle-resolved photoemission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Raj, S. [Department of Physics, Tohoku University, Sendai 980-8578 (Japan)]. E-mail: raj@arpes.phys.tohoku.ac.jp; Hashimoto, D. [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); Matsui, H. [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); Souma, S. [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); CREST, Japan Science and Technology Agency (JST), Kawaguchi 332-0012 (Japan); Sato, T. [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); CREST, Japan Science and Technology Agency (JST), Kawaguchi 332-0012 (Japan); Takahashi, T. [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); CREST, Japan Science and Technology Agency (JST), Kawaguchi 332-0012 (Japan); Ray, S. [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012 (India); Chakraborty, A. [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012 (India); Sarma, D.D. [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012 (India); Mahadevan, P. [S.N. Bose National Centre for Basic Sciences, JD Block, Sector 3, Salt Lake, Kolkata 700098 (India); Oishi, S. [Faculty of Engineering, Shinshu University, Nagano 380-8553 (Japan); McCarroll, W.H. [Department of Chemistry and Biochemistry, Rider University, NJ 08648 (United States); Greenblatt, M. [Department of Chemistry and Chemical Biology, The State University of New Jersey, NJ 08854 (United States)

    2007-03-15

    We report high-resolution angle-resolved photoemission spectroscopy on sodium tungsten bronzes, Na{sub x}WO{sub 3}, which exhibit a metal-insulator transition as a function of x. We found that the near-E{sub F} states are localized in Na{sub x}WO{sub 3} (x=<0.25) due to the strong disorder caused by the random distribution of Na{sup +} ions in the WO{sub 3} lattice, which makes the system insulating. In the metallic regime we found that the rigid shift of band structure can explain the metallic Na{sub x}WO{sub 3} band structure with respect to Na doping.

  5. Corrosion evaluation of multi-pass welded nickel–aluminum bronze alloy in 3.5% sodium chloride solution: A restorative application of gas tungsten arc welding process

    International Nuclear Information System (INIS)

    Highlights: • Corrosion of GTA welded nickel–aluminum bronze (C95800) was studied. • Drastic microstructural changes occurred during the welding operations. • The β′ and α phases acts as anode and cathode, correspondingly, in weld region. • A few nanoamperes couple current was measured in ZRA test as galvanic corrosion. • Corrosion resistance of weld parts could not be weakened in marine environments. - Abstract: In this research, the corrosion behavior of a gas tungsten arc welded nickel–aluminum bronze (NAB) alloy is investigated by DC and AC electrochemical techniques in 3.5% sodium chloride solution. Regarding the electrochemical impedance spectroscopy and potentiodynamic results, uniform corrosion resistance of instantly immersed weld and base samples are almost analogous and increased (more in weld region) during the immersion times. Moreover, zero resistant ammeter results demonstrated that the few nanoampere galvanic currents are attributed to microstructural and morphological differences between these two regions. Therefore, the welding procedure could not deteriorate the general corrosion resistance of the restored damaged NAB parts operating in marine environments

  6. X-ray and electron diffraction study of the tetragonal sodium tungsten bronze, Na{sub 0.10}WO{sub 3}, with distorted perovskite structure

    Energy Technology Data Exchange (ETDEWEB)

    Triantafyllou, S.T.; Christidis, P.C.; Lioutas, C.B. [Aristotle Univ. of Thessaloniki (Greece)

    1997-11-01

    The crystal structure of the tetragonal sodium tungsten bronze, Na{sub 0.10}WO{sub 3}, was investigated by single-crystal X-ray and electron diffraction methods. The average structure has space group P4/nmm and cell constants a{sub av} = 5.2492(5) {angstrom}, c{sub av} = 3.8953(4) {angstrom}, and Z = 2. The superstructure has space group very probably P4 and cell constants a{sub s} = 7.423(3) {angstrom}, c{sub s} = 7.791(1) {angstrom}, and Z = 8. Full-matrix least-squares refinements resulted in a conventional R value of 0.041 [86 observed unique reflections, I > 2{sigma}(I)] for the average structure and an R value of 0.086 [537 observed unique reflections, I > 2{sigma}(I)] for the superstructure. The general features of the average structure, which is of distorted perovskite type, are the same as those reported earlier. The two axial bonds of the WO{sub 6}, octahedron are not equal (1.95 {angstrom}) as observed in the previous work but have significantly different lengths [1.63(6) and 2.27(6){angstrom}]. The superstructure, reported for the first time, results from the average structure by the combined effects of tilting of the WO{sub 6} octahedra about c leading to a doubling of this axis (c{sub s} = 2c{sub av}) and of shape deformation of these octahedra in the ab plane leading to a supercell in this plane with a{sub s} = {radical}2 a{sub av}.

  7. Lithium intercalation in perovskite and hexagonal tungsten bronze derivatives

    International Nuclear Information System (INIS)

    Lithium has been intercalated chemically and electrochemically in LnNb3O9 (Ln = La,Nd) perovskite-type phases and LiW3O9F which can be considered as a hexagonal tungsten bronze derivative. The crystallographic formula of the LnNb3O9 starting material is described

  8. Reproducible nuclear reactions upon reaction of deuterium with tungsten oxide bronze

    International Nuclear Information System (INIS)

    Investigators of anomalous nuclear phenomena in condensed media have not been able to achieve 100% reproducibility of results on observation of emission of nuclear radiation. All these experiments were carried out with solids based on metal-hydrogen systems, neither the structure nor the crystallographic orientation of which can be controlled. In contrast to all the experiments performed so far, in order to achieve a high level of reproducibility the authors used fundamentally new materials as the objects of investigation: single crystals of tungsten oxide bronzes, nonstoichiometric compounds with general formula NaxWO3. As the working surface the authors used the (001) face of the crystal, perpendicular to which the channels of the rigid W-O sublattice are located. Alkali metal cations are located in these channels and can move through them. Depending on the alkali metal content in the tungsten oxide bronze, due to the variation in the valence state of the tungsten, oxide bronzes can vary over very broad limits. This allows the authors to create structures in the crystal with high composition in gradients and gradients in properties due to them and, in particular, to also use an electric field to control the movement of ions in the crystal. Using electrochemical methods (anodic treatment in salt melts, aqueous solutions, and under vacuum), sodium can be extracted from the channels in the surface layer of the bronze crystal and substituted by hydrogen (deuterium) ions

  9. Pyroelectric properties of ceramic with tetragonal bronze tungsten structure

    International Nuclear Information System (INIS)

    Ceramics of the tetragonal tungsten bronze type of structure (Srx Ba1-x) Nb2 O6 (SBN), with x=0.25, x=0.50 e x=0.75, were synthesized by conventional methods. The dielectric and pyroelectric properties were analyzed with intention to determine the potential of the SBN ceramics for pyroelectric detection. The pyroelectric properties of these ceramic materials are pioneer results in this area. (author)

  10. Novel polar dielectrics with the tetragonal tungsten bronze structure

    OpenAIRE

    Andrei ROTARU

    2013-01-01

    There is great interest in the development of new polar dielectric ceramics and multiferroic materials with new and improved properties. A family of tetragonal tungsten bronze (TTB) relaxors of composition Ba₆M³⁺Nb₉O₃₀ (M³⁺ = Ga³⁺, Sc³⁺ and In³⁺, and also their solid solutions) were studied in an attempt to understand their dielectric properties to enable design of novel polar TTB materials. A combination of electrical measurements (dielectric and impedance spectroscopy) and powder diffr...

  11. The metal–insulator transition in trivalent-ion-doped tungsten bronzes

    International Nuclear Information System (INIS)

    Electrical transport measurements have been made on a series of trivalent-ion-doped tungsten bronzes MxWO3, with M = Y (0.05 ≤ x ≤ 0.12) or La (0.05 ≤ x ≤ 0.19), over the temperature range 2–300 K. The results are consistent with a metal–insulator transition (MIT) at a critical concentration xC ≃ 0.06, which corresponds to an electron concentration nC ≃ 3.3 × 1021 cm−3. The appearance of small concentrations of non-cubic phases for x ∼ xC does not have a significant impact on the evolution of the electronic properties of the trivalent bronzes in the low x range. Analysis of the transport results, and a comparison of the findings with those obtained by other workers for the sodium tungsten bronzes, suggest that electron–electron interaction effects play a significant role in inducing the MIT in this type of disordered system. (paper)

  12. Density-functional studies of tungsten trioxide, tungsten bronzes, and related systems

    CERN Document Server

    Ingham, B; Chong, S V; Tallon, J L

    2005-01-01

    Tungsten trioxide adopts a variety of structures which can be intercalated with charged species to alter the electronic properties, thus forming `tungsten bronzes'. Similar optical effects are observed upon removing oxygen from WO_3, although the electronic properties are slightly different. Here we present a computational study of cubic and hexagonal alkali bronzes and examine the effects on cell size and band structure as the size of the intercalated ion is increased. With the exception of hydrogen (which is predicted to be unstable as an intercalate), the behaviour of the bronzes are relatively consistent. NaWO_3 is the most stable of the cubic systems, although in the hexagonal system the larger ions are more stable. The band structures are identical, with the intercalated atom donating its single electron to the tungsten 5d valence band. Next, this was extended to a study of fractional doping in the Na_xWO_3 system (0 < x < 1). A linear variation in cell parameter, and a systematic change in the po...

  13. Density-functional studies of tungsten trioxide, tungsten bronzes, and related systems

    Science.gov (United States)

    Ingham, B.; Hendy, S. C.; Chong, S. V.; Tallon, J. L.

    2005-08-01

    Tungsten trioxide adopts a variety of structures which can be intercalated with charged species to alter the electronic properties, thus forming “tungsten bronzes.” Similar effects are observed upon removing oxygen from WO3 . We present a computational study of cubic and hexagonal alkali bronzes and examine the effects on cell size and band structure as the size of the intercalated ion is increased. With the exception of hydrogen (which is predicted to be unstable as an intercalate), the behavior of the bronzes are relatively consistent. NaWO3 is the most stable of the cubic systems, although in the hexagonal system the larger ions are more stable. The band structures are identical, with the intercalated atom donating its single electron to the tungsten 5d valence band. A study of fractional doping in the NaxWO3 system (0⩽x⩽1) showed a linear variation in cell parameter and a systematic shift in the Fermi level into the conduction band. In the oxygen-deficient WO3-x system the Fermi level undergoes a sudden jump into the conduction band at around x=0.2 . Lastly, three compounds of a layered WO4•α,ω -diaminoalkane hybrid series were studied and found to be insulating, with features in the band structure similar to those of the parent WO3 compound that relate well to experimental UV-visible spectroscopy results.

  14. Photoelectrochemical production of atomic hydrogen at tungsten bronze/aqueous solution interface

    Energy Technology Data Exchange (ETDEWEB)

    Nagy, G.; Schiller, R.

    1988-12-01

    The cathodic photoeffect on hydrogenated sodium tungsten bronzes was studied in acid solutions under potentiostatic conditions. Solute effect proved the accompanying chemical reactions in the liquid phase to be brought about by hydrogen atoms. Kinetic analysis of the photocurrent showed that photoproduction and second-order recombination of the charge carriers in the solid are followed by reversible reduction of H/sup +/ at the interface. Finally H-atoms react with solutes like O/sub 2/, NO/sub 3//sup -/, Fe/sup 3+/, Fe(CN)/sub 6//sup 3-/, or tetranitromethane. The kinetics of charge carrier formation and of chemical reactions seem to be only weakly coupled, and the entire process can be described in terms of homogeneous kinetics showing diffusion and migration to be kinetically unimportant.

  15. Structural Analysis and Electrical Property of Tungsten Bronze Prepared by Rare Earth Gaseous Permeation

    Institute of Scientific and Technical Information of China (English)

    李中华; 李昕; 陈刚; 苏铭汉; 韦永德

    2004-01-01

    The cubic sodium tungsten bronzes, NaxWO3(x=0.854 and 0.814)were prepared by rare earths gaseous permeation method. Structural analysis was carried out by Rietveld method from powder X-ray diffraction data. The X-ray diffraction profile calculated with cubic P32 models are in good agreement with the observed X-ray diffraction patterns. There is only a little difference in W-O bond and Na-O bond between Na0.854WO3 and Na0.814WO3. Conductivity measurements indicate that NaxWO3 show anomalous semiconducting behavior and percolation model was used to interpret it.

  16. Thermal analysis of the Na2B4O7-Na2WO4-WO3 ternary system and synthesis of oxide tungsten bronzes in its melts

    International Nuclear Information System (INIS)

    The Na2B4O7-Na2WO4-WO3 ternary system is studied by thermal analysis. It is found that the liquidus surface consists of the crystallization fields of sodium tungstate, sodium tetraborate, tungsten oxide, and also congruently melting compounds (Na2WO4 · WO3, 2Na2WO4 · Na2B4O7, and 3Na2B4O7· WO3) and incongruently melting sodium tetratungstate (Na2WO4 · 3WO3), which are formed at the corresponding sides of the concentration triangle. Low-melting compositions that are of interest for the development of a chemical method for the synthesis of sodium tungsten oxide bronzes were identified

  17. Characterization and Photocatalytic Activity of KSr_2Nb_5O_(15) with Tungsten Bronze Structure

    Institute of Scientific and Technical Information of China (English)

    ZHANG Gaoke; LI Yiqiu; WANG Junting; TU Haibin; YU Xinyi

    2009-01-01

    Tungsten bronze(TB)type potassium strontium niobate KSr_2Nb_5O_(15) was prepared by solid-state reaction method,and was characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM)and UV-vis diffuse spectrum.The photocatalyst shows high photocatalytic activity of photodegrading acid red G.The effects of photocatalyst dosage and initial concentration of acid red G on the photodegradation process were studied.The kinetics of photocatalytic degradation of acid red G by KSr_2Nb_5O_(15) catalyst follows the first order reaction.

  18. Studies of solids at low temperatures. Final scientific report. [Fluoro-tungsten bronzes

    Energy Technology Data Exchange (ETDEWEB)

    Moulton, W.G.

    1970-10-01

    One of the primary objectives of this research has been to investigate the magnetic properties of materials which are likely to exhibit unusual magnetic transitions which may prove to be useful for microwave or switching devices. Experimental techniques used in this research included nuclear magnetic resonance, magnetic susceptibility measurements, optical spectroscopy, and electron spin resonance. A second goal was to develop relationships between magnetic properties and chemical bonding so that eventually magnetic properties could be predicted from the structure of a compound. Another objective of this research was to investigate the possibility of superconductivity in the fluoro-tungsten bronzes. Forty-two of these compounds were synthesized and all were found to have superconducting transition temperatures between one and one half degrees and five degrees kelvin. Relationships between the critical fields and the transition temperature and the composition have been established.

  19. The Preparation and Characterization of a Sodium Tungsten Bronze

    Science.gov (United States)

    Conroy, Lawrence E.

    1977-01-01

    Describes an experiment that utilizes the techniques of temperature synthesis, crystallization from a molten salt, oxidation-reduction in a molten salt, powder X-ray diffraction and analysis by high temperature volatilization or a specific ion electrode. (MLH)

  20. Origin of ferroelectric polarization in tetragonal tungsten-bronze-type oxides

    Science.gov (United States)

    Olsen, Gerhard Henning; Aschauer, Ulrich; Spaldin, Nicola A.; Selbach, Sverre Magnus; Grande, Tor

    2016-05-01

    The origin of ferroelectric polarization in tetragonal tungsten-bronze- (TTB-) type oxide strontium barium niobate (SBN) is investigated using first-principles density functional calculations. We study in particular the relationship between the polarization and the cation and vacancy ordering on alkali-earth metal lattice sites. Lattice dynamical calculations for paraelectric structures demonstrate that all cation configurations that can be accommodated in a 1 ×1 ×2 supercell result in a single unstable polar phonon, composed primarily of relative Nb-O displacements along the polar axis, as their dominant instability. The majority of the configurations also have a second octahedral tilt-mode instability which couples weakly to the polar mode. The existence of the tilt mode is strongly dependent on the local cation ordering, consistent with the fact that it is not found experimentally. Our results suggest that ferroelectricity in the SBN system is driven by a conventional second-order Jahn-Teller mechanism caused by the d0 Nb5 + cations, and demonstrate the strong influence of the size of Sr and Ba on the lattice distortions associated with polarization and octahedral tilting. Finally, we suggest a mechanism for the relaxor behavior in Sr-rich SBN based on Sr displacement inside pentagonal channels in the TTB structure.

  1. Phase transition and conduction mechanism of rare earth based tungsten-bronze compounds

    International Nuclear Information System (INIS)

    Highlights: ► The materials have very good ferroelectric properties for memory devices. ► The material has very good pyroelectric properties for detector application. ► Also these materials behave very good semiconducting properties. - Abstract: The polycrystalline materials (Li2Pb2R2W2Ti4Nb4O30 (R = Y, Eu)) of tungsten-bronze structural family have been synthesized using a high-temperature solid-state reaction (mixed-oxide) technique. The formation of the single phase compounds was checked using preliminary X-ray structural data/pattern. The nature and distribution of grains in the samples in the scanning electron micrographs (SEM) confirm the good quality of the samples used for electrical characterization. The phase transition (ferroelectric–paraelectric) in the materials was established through the detailed studies of dielectric, electric polarization and pyro-electric properties. Studies of pyroelectric properties show that the materials have reasonably high figure of merit useful for pyroelectric detector. The nature of frequency dependence of ac conductivity suggests that the materials obey Jonscher’s universal power law.

  2. Release of copper from sintered tungsten-bronze shot under different pH conditions and its potential toxicity to aquatic organisms.

    Science.gov (United States)

    Thomas, Vernon G; Santore, Robert C; McGill, Ian

    2007-03-01

    Sintered tungsten-bronze is a new substitute for lead shot, and is about to be deposited in and around the wetlands of North America. This material contains copper in the alloyed form of bronze. This in vitro study was performed according to U.S. Fish and Wildlife Service criteria to determine the dissolution rate of copper from the shot, and to assess the toxic risk that it may present to aquatic organisms. The dissolution of copper from tungsten-bronze shot, pure copper shot, and glass beads was measured in a buffered, moderately hard, synthetic water of pH 5.5, 6.6, and 7.8 over a 28-day period. The dissolution of copper from both the control copper shot and the tungsten-bronze shot was affected significantly by the pH of the water and the duration of dissolution (all p valueswater quality criteria database, were all far less than the 0.1 criterion value. Given the conditions stipulated by the U.S. Fish and Wildlife Service and the U.S. Environmental Protection Agency, heavy loading from discharged tungsten-bronze shot would not pose a toxic risk to potable water, or to soil. Consequently, it would appear that no toxic risks to aquatic organisms will attend the use of tungsten-bronze shot of the approved composition. Given the likelihood that sintered tungsten-bronze of the same formula will be used for fishing weights, bullets, and wheel balance weights, it is expected that the use of this new material in these applications will not be associated with toxic risks to aquatic life. PMID:17276492

  3. The optical properties of lithium tungsten bronze single crystals and thin films for electrochromic window device applications

    Energy Technology Data Exchange (ETDEWEB)

    Berera, G.P.

    1992-01-01

    The optical and structural properties of rf sputter deposited thin films of Li[sub x]WO[sub 3], prepared by insertion of lithium either electrochemically or by sputter depositing lithium aluminum borate (LABO) or lithium carbonate (LCO) were studied as a function of lithium concentration. Single crystals of Li[sub x]WO[sub 3] were studied. The results were compared with results for sodium tungsten bronze (Na[sub x]WO[sub 3]) single crystals. From the optical data, physical parameters such as effective mass and intrinsic band gap of Li[sub x]WO[sub 3] as a function of x were determined. A progression in the crystal structure from monoclinic to cubic for higher values of x was observed for both Li[sub x]WO[sub 3] and Na[sub x]WO[sub 3]. In the cubic regime a lattice contraction and an expansion was observed with x for Li[sub x]WO[sub 3] and Na[sub x]WO[sub 3]. Rf sputter deposited films were polycrystalline and the degree of crystallinity was observed to increase with deposition temperature and sample annealing. The crystal structure of the films was reversible upon insertion and removal of lithium. The optical reflectivity spectrum exhibited a free electron like behavior and increased with increasing x. The optical reflectivity spectrum for the lithiated WO[sub 3] films behaved similarly to that of single crystals. The free electron scattering was higher for the thin films. Films which were annealed showed higher R([lambda]) and lower scattering compared to unannealed films. Crystalline perfection of the films appeared to be a key factor in achieving a high R([lambda]). The electron effective mass and the intrinsic band gap decreased with increasing x in Li[sub x]WO[sub 3]. Highly crystalline lithiated tungsten trioxide thin films are well suited for the working electrode in electrochromic [open quotes]SMART WINDOW[close quotes] devices, and improved crystallinity of these films will result in further improvement of device performance.

  4. Chemical bath deposition and characterization of electrochromic thin films of sodium vanadium bronzes

    Energy Technology Data Exchange (ETDEWEB)

    Najdoski, Metodija, E-mail: metonajd@yahoo.com [Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Sts. Cyril and Methodius University, POB 162, Arhimedova 5, 1000 Skopje, Republic of Macedonia (Macedonia, The Former Yugoslav Republic of); Koleva, Violeta [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Demiri, Sani [Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Sts. Cyril and Methodius University, POB 162, Arhimedova 5, 1000 Skopje, Republic of Macedonia (Macedonia, The Former Yugoslav Republic of)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer We report a new chemical bath method for the deposition of vanadium bronze thin films. Black-Right-Pointing-Pointer The films are phase mixture of NaV{sub 6}O{sub 15} and Na{sub 1.1}V{sub 3}O{sub 7.9} with 10.58% lattice water. Black-Right-Pointing-Pointer The as-deposited vanadium bronze films exhibit two-step electrochromism. Black-Right-Pointing-Pointer They change their yellow-orange color to green and then from green to blue color. Black-Right-Pointing-Pointer The method allows the preparation of films on substrates with low melting point. -- Abstract: Thin yellow-orange films of sodium vanadium oxide bronzes have been prepared from a sodium-vanadium solution (1:1) at 75 Degree-Sign C and pH = 3. The composition, structure and morphology of the films have been studied by XRD, IR spectroscopy, TG and SEM-EDX analyses. It has been established that the prepared films are a phase mixture of hydrated NaV{sub 6}O{sub 15} (predominant component) and Na{sub 1.1}V{sub 3}O{sub 7.9} with total water content of 10.58%. The sodium vanadium bronze thin films exhibit two-step electrochromism followed by color change from yellow-orange to green, and then from green to blue. The cyclic voltammetry measurements on the as-deposited and annealed vanadium bronze films reveal the existence of different oxidation/reduction vanadium sites which make these films suitable for electrochromic devices. The annealing of the films at 400 Degree-Sign C changes the composition, optical and electrochemical properties.

  5. Release of copper from sintered tungsten-bronze shot under different pH conditions and its potential toxicity to aquatic organisms

    International Nuclear Information System (INIS)

    Sintered tungsten-bronze is a new substitute for lead shot, and is about to be deposited in and around the wetlands of North America. This material contains copper in the alloyed form of bronze. This in vitro study was performed according to U.S. Fish and Wildlife Service criteria to determine the dissolution rate of copper from the shot, and to assess the toxic risk that it may present to aquatic organisms. The dissolution of copper from tungsten-bronze shot, pure copper shot, and glass beads was measured in a buffered, moderately hard, synthetic water of pH 5.5, 6.6, and 7.8 over a 28-day period. The dissolution of copper from both the control copper shot and the tungsten-bronze shot was affected significantly by the pH of the water and the duration of dissolution (all p values < 0.000). The rate of copper release from tungsten bronze shot was 30 to 50 times lower than that from the copper shot, depending on pH (p < 0.0000). The observed expected environmental concentration of copper released from tungsten-bronze shot after 28 days was 0.02 μg/L at pH 7.8, and 0.4 μg/L at pH 5.6, using a loading and exposure scenario specific in a U.S. Fish and Wildlife Service protocol. Ratio Quotient values derived from the highest EEC observed in this study (0.4 μg/L), and the copper toxic effect levels for all aquatic species listed in the U.S. Environmental Protection Agency ambient water quality criteria database, were all far less than the 0.1 criterion value. Given the conditions stipulated by the U.S. Fish and Wildlife Service and the U.S. Environmental Protection Agency, heavy loading from discharged tungsten-bronze shot would not pose a toxic risk to potable water, or to soil. Consequently, it would appear that no toxic risks to aquatic organisms will attend the use of tungsten-bronze shot of the approved composition. Given the likelihood that sintered tungsten-bronze of the same formula will be used for fishing weights, bullets, and wheel balance weights, it is

  6. Chemical bath deposition and characterization of electrochromic thin films of sodium vanadium bronzes

    International Nuclear Information System (INIS)

    Highlights: ► We report a new chemical bath method for the deposition of vanadium bronze thin films. ► The films are phase mixture of NaV6O15 and Na1.1V3O7.9 with 10.58% lattice water. ► The as-deposited vanadium bronze films exhibit two-step electrochromism. ► They change their yellow-orange color to green and then from green to blue color. ► The method allows the preparation of films on substrates with low melting point. -- Abstract: Thin yellow-orange films of sodium vanadium oxide bronzes have been prepared from a sodium–vanadium solution (1:1) at 75 °C and pH = 3. The composition, structure and morphology of the films have been studied by XRD, IR spectroscopy, TG and SEM–EDX analyses. It has been established that the prepared films are a phase mixture of hydrated NaV6O15 (predominant component) and Na1.1V3O7.9 with total water content of 10.58%. The sodium vanadium bronze thin films exhibit two-step electrochromism followed by color change from yellow-orange to green, and then from green to blue. The cyclic voltammetry measurements on the as-deposited and annealed vanadium bronze films reveal the existence of different oxidation/reduction vanadium sites which make these films suitable for electrochromic devices. The annealing of the films at 400 °C changes the composition, optical and electrochemical properties

  7. Relaxor nature in lead-free Sr5LaTi3Nb7O30 tetragonal tungsten bronze ceramics

    International Nuclear Information System (INIS)

    Lead-free tetragonal tungsten bronze Sr5LaTi3Nb7O30 ceramics were prepared and the correlation of the relaxor nature and crystal structure was studied using dielectric spectroscopy and powder X-ray diffraction. Three dielectric relaxations were observed below the deviation temperature TD∼ 330 K. Relaxation I and II followed the Vogel-Fulcher law with the freezing temperatures of 189 K and ∼90 K. Low temperature relaxation III, which was first observed in filled tungsten bronze, followed well the Arrhenius law. Dielectric response becomes static below 50 K. Polarization-field (P-E) hysteresis loops were evaluated from 183 K to 298 K. Pr value of 0.41μC/cm2 was observed at 183 K. Deviation of lattice parameter c from the linear contraction and increasing of tetragonality (c/a ratio) were observed below TD, reflecting the structure change during the formation of polar nanoregions and the following freezing process. Opposite tendency was observed below 100 K for all the lattice parameters, corresponding to relaxation III. Generally, the main dielectric relaxation I and II were attributed to flipping and breathing of polar nanoregions along c axis, while the concerted rotations of the oxygen octahedra in the ab plane were suggested as the origin of relaxation III

  8. Low-temperature electrical conductivity of Ta-compensated sodium bronze near the metal-insulator transition

    International Nuclear Information System (INIS)

    We report the results of electrical conductivity [σ(T)] measurements in the temperature range 300>T>0.1 K on single crystals of tantalum-substituted sodium tungsten bronze (NaxTayW1-yO3) with compositions near the metal-insulator transition (x-y∼0.19). We find that over the entire temperature range investigated, strong interaction effects dominate the temperature dependences of σ(T). For samples that lie on the metallic side, the σ(T) values in the temperature range 4>T>0.3 K follow a power law in T with an exponent 1/3 and σ(T=0)∼0.01σMott. This arises due to interaction effects in the critical regime, where the coherence length is very large due to the proximity to the metal-insulator transition. These samples below 0.3 K show signatures of a weak superconducting transition. The σ(T) of the insulating samples below 4 K either show correlated hopping behavior or follow a power law with σ(T=0)=0. At higher temperatures (T>10 K), the σ(T) of both types of samples show an almost linear dependence with T, which we suggest as arising from electron-phonon interactions

  9. Dissolution of copper, tin, and iron from sintered tungsten-bronze spheres in a simulated avian gizzard, and an assessment of their potential toxicity to birds

    International Nuclear Information System (INIS)

    The rates of dissolution of copper, tin, and iron from sintered tungsten-bronze spheres (51.1%W, 44.4%Cu, 3.9%Sn, 0.6%Fe, by mass) were measured in an in vitro simulated avian gizzard at pH 2.0, and 42C. Most of the spheres had disintegrated completely to a fine powder by day 14. Dissolution of copper, tin, and iron from the spheres was linear over time; all r > 0.974; all P < 0.001. The mean rate of release of copper, tin, and iron was 30.4 mg, 2.74 mg, and 0.38 mg per g tungsten-bronze per day, respectively. These rates of metal release were compared to those in published studies to determine whether the simultaneous ingestion of eight spheres of 3.48 mm diameter would pose a toxic risk to birds. The potential absorption rates of iron and tin (0.54 mg Fe/day, and 3.89 mg Sn/day) from eight tungsten-bronze spheres of total mass 1.42 g would not prove toxic, based on empirical studies of tin and iron ingestion in waterfowl. The release of 43.17 mg copper/day from eight tungsten-bronze spheres, while exceeding the daily copper requirements of domesticated birds, is far below the levels of copper known to cause copper toxicosis in birds. We conclude that sintered tungsten-bronze material made into gunshot, fishing weights, or wheel balance weights, would not pose a toxic risk to wild birds when ingested

  10. The preparation and chemical reaction kinetics of tungsten bronze thin films and nitrobenzene with and without a catalyst

    Science.gov (United States)

    Materer, Nicholas F.; Apblett, Allen; Kadossov, Evgueni B.; Khan, Kashif Rashid; Casper, Walter; Hays, Kevin; Shams, Eman F.

    2016-06-01

    Microcrystalline tungsten bronze thin films were prepared using wet chemical techniques to reduce a tungsten oxide thin film that was prepared by thermal oxidation of a sputter deposited tungsten metal film on a quartz substrate. The crystallinity of these films was determined by X-ray diffraction and the surface was characterized by X-ray and Ultra-Violet Photoelectron spectroscopy. The total amount of hydrogen incorporated in the film was monitored using absorbance spectroscopy at 900 nm. The oxidation kinetics of the film and the hydrogenation of nitrobenzene in hexane were measured as a function of film thickness. A satisfactory fit of the resulting kinetics was obtained using a model that involves two simultaneous processes. The first one is the proton diffusion from the bulk of the film to the surface, and the second is a reaction of the surface protons with the oxidants. Finally, the dependence of the reaction rates on the presence of catalytic amounts of first row transition metals on the surface of the film was explored.

  11. Crystallographic analysis of the solid solution of iron doped potassium strontium niobate with tetragonal tungsten bronze structure

    International Nuclear Information System (INIS)

    Solid solution of iron doped potassium strontium niobate with KSr2(FeNb4)O15-δ stoichiometry was prepared by high efficiency ball milling method. Structural characterization was carried out by X-ray diffraction. Crystalline structure was analyzed by the Rietveld refinements using the FullProf software. The results showed a tetragonal system with the tetragonal tungsten bronze structure - TTB (a = 12.4631 (2) A and c = 3.9322 (6) A, V = 610.78 (2) A3). In this work, the sites occupancy by the K+, Sr2+ and Fe3+ cations on the TTB structure were determined. NbO6 polyhedra distortion and its correlation with the theoretical polarization are discussed. (author)

  12. Solvothermal Synthesis of Caesium Tungsten Bronze in the Presence of Various Organic Acids and Its NIR Absorption Properties

    International Nuclear Information System (INIS)

    Nanoparticles of caesium tungsten bronze were successfully synthesized by solvothermal reactions in ethanol with the introduction of different organic fatty acids with various carbon numbers of 1 to 5. Compared to the sample prepared in pure ethanol, the samples obtained by mixed solvent of ethanol and fatty acids showed higher production yield, smaller particle size, more uniform particles size distribution and higher Cs/W atomic ratio. In addition, all of samples obtained using acids-ethanol mixed solvent exhibited higher visible light transmittance and greater NIR absorption performance, indicating the potential application for smart window and heat-ray shielding materials. The addition of acetic acid showed the best performance to facilitate the formation of well dispersed CsxWO3 regular nanorods, leading to its excellent optical properties.

  13. Comparative study of tantalates with the ''tetragonal tungsten bronze'' structure including Ce4+, Th4+ or U4+ ions

    International Nuclear Information System (INIS)

    The thorium-lead and uranium-lead substitutions in Pbsub(2.5)Ta5O15(PbTa2O6) and Pb2KTa5O15 had allowed to prepare new solid solutions with ''tetragonal tungsten bronze'' structure. The progressive replacement of lead by cerium in the same compounds has lead us to the new solid solutions with the identical structure. All these materials Pbsub(2.5-2x)Msub(x)Ta5O15 (05O15 with M=Ce, Th or U belong to quadratic system having piezoelectric and ferroelectric properties. The substitution of lead by cerium, thorium, or uranium is responsible of the decrease of the crystalline parameters and of the ferroelectric Curie temperature

  14. Behavior of the monophosphate tungsten bronzes (PO2)4(WO3)2m (m = 7 and 8) in the course of electrochemical lithium insertion

    International Nuclear Information System (INIS)

    The electrochemical lithium insertion process has been studied in the family of monophosphate tungsten bronzes (PO2)4(WO3)2m, where m = 7 and 8. Structural changes in the pristine oxides were followed as lithium insertion proceeded. Through potentiostatic intermittent technique the different processes which take place in the cathode during the discharge of the cell were analyzed. The nature of the bronzes Li x(PO2)4(WO3)2m formed was determined by in situ X-ray diffraction experiments. These results have allowed establishing a correlation with the reversible/irreversible processes detected during the electrochemical lithium insertion

  15. A Facile One-Step Solvothermal Synthesis and Electrical Properties of Reduced Graphene Oxide/Rod-Shaped Potassium Tungsten Bronze Nanocomposite.

    Science.gov (United States)

    Liu, Bin; Yin, Shu; Wang, Yuhua; Guo, Chongshen; Wu, Xiaoyong; Dong, Qiang; Kobayashi, Makoto; Kakihana, Masato; Sato, Tsugio

    2015-09-01

    Reduced graphene oxide (rGO)/rod-shaped potassium tungsten bronze nanocomposites with the different ratio were successfully synthesized by solvothermal reaction and followed by the reduction in H2(5 vol.%)/N2 atmosphere at 550 degrees C. The coupled samples showed excellent shielding ability of NIR light as well as certain visible lights transparency. The synergistic effects could be observed in the composites, i.e., when 15 wt% and 20 wt% of rGO which was fabricated by chemical reduction of graphene oxide, were composed into K(x)WO3, the composite showed the higher electrical conductivity than those of rGO and potassium tungsten bronze. PMID:26716327

  16. High temperature magnetic anomalie in NaxWO3 single crystals at low sodium content

    International Nuclear Information System (INIS)

    Sodium tungsten bronze single crystals with low sodium content (x≅0.14) were grown by the electrochemical reduction method. The magnetic and transport properties of the obtained NaxWO3 samples were investigated. The results of SQUID magnetic measurements show presence of a magnetic anomalie at 150 K. It indicates the possible existence of the high-temperature superconducting phase in sodium tungsten bronzes

  17. Low-temperature electrical conductivity of Ta-compensated sodium bronze near the metal-insulator transition

    Energy Technology Data Exchange (ETDEWEB)

    Raychaudhuri, A.K. (Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853 and %Department of Physics, Indian Institute of Science, Bangalore 560 012 (India))

    1991-10-15

    We report the results of electrical conductivity ({sigma}({ital T})) measurements in the temperature range 300{gt}{ital T}{gt}0.1 K on single crystals of tantalum-substituted sodium tungsten bronze (Na{sub {ital x}}Ta{sub {ital y}}W{sub 1{minus}{ital y}}O{sub 3}) with compositions near the metal-insulator transition ({ital x}{minus}{ital y}{approx}0.19). We find that over the entire temperature range investigated, strong interaction effects dominate the temperature dependences of {sigma}({ital T}). For samples that lie on the metallic side, the {sigma}({ital T}) values in the temperature range 4{gt}{ital T}{gt}0.3 K follow a power law in {ital T} with an exponent 1/3 and {sigma}({ital T}=0){approx}0.01{sigma}{sub Mott}. This arises due to interaction effects in the critical regime, where the coherence length is very large due to the proximity to the metal-insulator transition. These samples below 0.3 K show signatures of a weak superconducting transition. The {sigma}({ital T}) of the insulating samples below 4 K either show correlated hopping behavior or follow a power law with {sigma}({ital T}=0)=0. At higher temperatures ({ital T}{gt}10 K), the {sigma}({ital T}) of both types of samples show an almost linear dependence with {ital T}, which we suggest as arising from electron-phonon interactions.

  18. Synthesis of K0.3WO3 tungsten bronze with gaseous permeation of K3PW12O40 by Sm and electrical properties of K0.3WO3 tungsten bronze

    International Nuclear Information System (INIS)

    The permeation of the rare earth element Sm to the heteropoly compound K3PW12O40 using the rare earth gas phase-heated diffused permeation method at 550 deg. C is reported for the first time. The studies of infrared spectroscopy (IR) and X-ray diffraction (XRD) indicate that the Keggin structure of the compound is destroyed. The bond of W-O-W is broken and tungsten bronze K0.3WO3 is produced after permeation. Inductively coupled plasma (ICP) and X-ray photoelectron spectroscopy (XPS) were used to determine the percentage composition of the Sm in a permeated sample. The result shows that there is Sm in a permeated sample and Sm interacts with the other component of the compound. Conductivity of compounds before and after permeation was investigated by four-electrode method. It reveals that the conductivity of the permeated sample is 4.18 x 10-4 S cm-1, which is 1000 times higher than that of the original sample

  19. High temperature magnetic anomalie in Na{sub x}WO{sub 3} single crystals at low sodium content

    Energy Technology Data Exchange (ETDEWEB)

    Garif' yanov, N.N.; Vavilova, E.L

    2003-01-01

    Sodium tungsten bronze single crystals with low sodium content (x{approx_equal}0.14) were grown by the electrochemical reduction method. The magnetic and transport properties of the obtained Na{sub x}WO{sub 3} samples were investigated. The results of SQUID magnetic measurements show presence of a magnetic anomalie at 150 K. It indicates the possible existence of the high-temperature superconducting phase in sodium tungsten bronzes.

  20. On the nature of phase transitions in the tetragonal tungsten bronze GdK2Nb5O15 ceramics

    International Nuclear Information System (INIS)

    Phase transitions in gadolinium potassium niobate GdK2Nb5O15 (GKN) ceramics have been investigated by x-ray diffraction, dielectric susceptibility, differential scanning calorimetry, and Raman scattering. The results of our complementary studies show that GKN exhibits two phase transitions at Tc1 = 238 °C and Tc2 = 375 °C attributed to the ferroelectric-antiferroelectric-paraelectric (FE-AFE-PE) phase transitions. According to the x-ray diffraction analysis, the FE and PE phases were refined in the polar P4bm and centrosymmetric P4/mbm space groups. For the intermediate phase, the structure is refined in the space group P4nc with doubling of the c unit cell parameter, which is compatible with an AFE phase. This result was confirmed by Raman spectroscopy since new low-frequency lines are activated in the AFE phase due to the Brillouin zone-folding effect, typical for the modulated phases. The presence of the AFE phase between the FE and PE phases and the complex nature of tetragonal tungsten bronze crystal structure can explain the large thermal hysteresis observed at the FE-AFE transition between heating and cooling cycle and the strong depression of the Curie-Weiss temperature T0. The semi-phenomenological Ising-like model based on the obtained experimental data is proposed to account for the observed FE-AFE-PE transition sequence

  1. Electrodeposition fabrication of pore-arrayed hydrogen tungsten bronze as support of platinum nanoparticles for electrocatalytic oxidation of methanol oxidation

    International Nuclear Information System (INIS)

    Highlights: • Pore-arrayed HxWO3 was fabricated using PS spheres as template by electrodepostion. • Pt nanoparticles can be stabilized on pore-arrayed HxWO3. • Pt supported by pore-arrayed HxWO3 exhibits excellent activity toward methanol oxidation. - Abstract: Pore-arrayed hydrogen tungsten bronze (p-HxWO3) is fabricated with polystyrene as template by electrodeposition and used as the support of platinum nanoparticles as electrocatalyst (Pt/p-HxWO3) for methanol oxidation. The surface morphology, structure, and compositions of p-HxWO3 and Pt/p-HxWO3 are characterized with scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). The activity and stability of Pt/p-HxWO3 toward methanol oxidation are evaluated in 0.5 M H2SO4 + 1.0 M CH3OH solution by cyclic voltammetry (CV), chronoamperometry (CA), and chronopotentiometry (CP), and cell discharge test. The characterizations from SEM, XRD, TEM, and FTIR demonstrate that p-HxWO3 contains uniform pores of about 200 nm and the platinum particles can be uniformly distributed with an average size of 3.01 nm on it. The electrochemical evaluations indicate that Pt/p-HxWO3 exhibits better activity and stability toward methanol oxidation than the platinum supported by non-pore arrayed HxWO3

  2. Crystal structure and superconductivity of rubidium tungsten bronzes RbxWO3 prepared by a hybrid microwave method

    International Nuclear Information System (INIS)

    The rubidium tungsten bronzes RbxWO3 have been prepared from Rb2CO3, WO3 and W powders using hybrid microwave method. The single hexagonal phase samples can be obtained as actual rubidium content x in the range of 0.21-0.33, and their lattice parameters a and c linearly drop and rise with the increase of rubidium content respectively. For samples with x = 0.14, 0.16, 0.18, the superconducting transition temperature Tc from resistivity measurements does not change with the rubidium content, while Tc from susceptibility measurements shows a decrease from 5.3 K for x = 0.14 to 4.8 K for x = 0.18. The charge density wave (CDW) transition appears in Rb0.21WO3, Rb0.23WO3 and Rb0.25WO3 at about 200-260 K. The CDW transition is most obvious in Rb0.23WO3 which shows the lowest degree of crystallization among the samples

  3. Dielectric relaxation and ac conductivity of sodium tungsten phosphate glasses

    Indian Academy of Sciences (India)

    B Singh; P S Tarsikka; L Singh

    2002-10-01

    Studies of dielectric relaxation and ac conductivity have been made on three samples of sodium tungsten phosphate glasses over a temperature range of 77–420 K. Complex relative permittivity data have been analyzed using dielectric modulus approach. Conductivity relaxation frequency increases with the increase of temperature. Activation energy for conductivity relaxation has also been evaluated. Measured ac conductivity (m()) has been found to be higher than dc at low temperatures whereas at high temperature m() becomes equal to dc at all frequencies. The ac conductivity obeys the relation ac() = A over a considerable range of low temperatures. Values of exponent are nearly equal to unity at about 78 K and the values decrease non-linearly with the increase of temperature. Values of the number density of states at Fermi level ((F)) have been evaluated at 80 K assuming values of electron wave function decay constant to be 0.5 (Å)-1. Values of (F) have the order 1020 which are well within the range suggested for localized states. Present values of (F) are smaller than those for tungsten phosphate glasses.

  4. Thermal Expansion and Second Harmonic Generation Response of the Tungsten Bronze Pb2AgNb5O15.

    Science.gov (United States)

    Lin, Kun; Gong, Pifu; Sun, Jing; Ma, Hongqiang; Wang, You; You, Li; Deng, Jinxia; Chen, Jun; Lin, Zheshuai; Kato, Kenichi; Wu, Hui; Huang, Qingzhen; Xing, Xianran

    2016-03-21

    The incorporation of transition metal element Ag was performed to explore negative thermal expansion (NTE) materials with tetragonal tungsten bronze (TTB) structures. In this study, the structure and thermal expansion behaviors of a polar TTB oxide, Pb2AgNb5O15 (PAN), were systematically investigated by high-resolution synchrotron powder diffraction, high-resolution neutron powder diffraction, transmission electron microscope (TEM), and high-temperature X-ray diffractions. The TEM and Rietveld refinements revealed that the compound PAN displays (√2a(TTB), √2b(TTB), 2c(TTB))-type superstructure. This superstructure within the a-b plane is caused by the ordering of A-site cations, while the doubling of the c axis is mainly induced by a slight tilt distortion of the NbO6 octahedra. The transition metal Ag has larger spontaneous polarization displacements than Pb, but the Pb-O covalence seems to be weakened compared to the potassium counterpart Pb2KNb5O15 (PKN), which may account for the similar Curie temperature and uniaxial NTE behavior for PAN and PKN. Powder second harmonic generation (SHG) measurement indicates that PAN displays a moderate SHG response of ∼0.2 × LiNbO3 (or ∼100 × α-SiO2) under 1064 nm laser radiation. The magnitudes of the local dipole moments in NbO6 and PbOx polyhedra were quantified using bond-valence approach. We show that the SHG response stems from the superposition of dipole moments of both the PbO(x) and NbO6 polyhedra. PMID:26928907

  5. Crystallographic analysis of the solid solution of iron doped potassium strontium niobate with tetragonal tungsten bronze structure; Analise cristalografica da solucao solida com estrutura tipo Tungstenio Bronze de niobato de potassio e estroncio dopado com ferro

    Energy Technology Data Exchange (ETDEWEB)

    Lanfredi, Silvania; Nobre, Marcos A.L., E-mail: silvania@fct.unesp.b [UNESP, Presidente Prudente, SP (Brazil). Faculdade de Ciencias e Tecnologia. Dept. de Fisica, Quimica e Biologia; Lima, Alan R.F. [Universidade Estadual de Ponta Grossa (DQ/UEPG), PR (Brazil). Dept. de Quimica

    2010-07-01

    Solid solution of iron doped potassium strontium niobate with KSr{sub 2}(FeNb{sub 4})O{sub 15-{delta}} stoichiometry was prepared by high efficiency ball milling method. Structural characterization was carried out by X-ray diffraction. Crystalline structure was analyzed by the Rietveld refinements using the FullProf software. The results showed a tetragonal system with the tetragonal tungsten bronze structure - TTB (a = 12.4631 (2) A and c = 3.9322 (6) A, V = 610.78 (2) A{sup 3}). In this work, the sites occupancy by the K{sup +}, Sr{sup 2+} and Fe{sup 3+} cations on the TTB structure were determined. NbO{sub 6} polyhedra distortion and its correlation with the theoretical polarization are discussed. (author)

  6. The crystal chemistry of the tetragonal tungsten-bronze: Ba6FeNb9O30

    International Nuclear Information System (INIS)

    Solid state reaction of BaCO3, FeC2O4 x 2 H2O and Nb2O5 gave single crystals of Ba6FeNb9O30. The crystal strucuture was solved by X-ray investigations (a = 12.597, c = 3.990 Ao, space group P4 bm - C4v2, Z = 1). Ba6FeNb9O30 crystallyzes in the tetragonal bronze type with a statistical distribution of Fe3+ and Nb5+ in the octahedral framework. The anisotropic temperature factors of barium are discussed with respect to the oxygen coordination. (Author)

  7. On the nature of phase transitions in the tetragonal tungsten bronze GdK{sub 2}Nb{sub 5}O{sub 15} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Gagou, Y.; Lukyanchuk, I.; El Marssi, M., E-mail: mimoun.elmarssi@u-picardie.fr [Laboratoire de Physique de la Matière Condensée, Université de Picardie Jules Verne, 33 rue Saint-Leu, 80039 Amiens Cedex (France); Amira, Y. [Laboratoire de Physique de la Matière Condensée, Université de Picardie Jules Verne, 33 rue Saint-Leu, 80039 Amiens Cedex (France); Laboratoire de la Matière Condensée et Nanostructures, FSTG, Université Cadi Ayyad Marrakech, Maroc (Morocco); Mezzane, D. [Laboratoire de la Matière Condensée et Nanostructures, FSTG, Université Cadi Ayyad Marrakech, Maroc (Morocco); Courty, M.; Masquelier, C. [Laboratoire de Réactivité et Chimie des Solides, UMR 7314, Université de Picardie Jules Verne, Pôle Scientifique, 33 rue Saint-Leu, 80039 Amiens Cedex 1 (France); Yuzyuk, Yu. I. [Faculty of Physics, Southern Federal University, 5, Zorge Str. Rostov-on-Don 344090 (Russian Federation)

    2014-02-14

    Phase transitions in gadolinium potassium niobate GdK{sub 2}Nb{sub 5}O{sub 15} (GKN) ceramics have been investigated by x-ray diffraction, dielectric susceptibility, differential scanning calorimetry, and Raman scattering. The results of our complementary studies show that GKN exhibits two phase transitions at T{sub c1} = 238 °C and T{sub c2} = 375 °C attributed to the ferroelectric-antiferroelectric-paraelectric (FE-AFE-PE) phase transitions. According to the x-ray diffraction analysis, the FE and PE phases were refined in the polar P4bm and centrosymmetric P4/mbm space groups. For the intermediate phase, the structure is refined in the space group P4nc with doubling of the c unit cell parameter, which is compatible with an AFE phase. This result was confirmed by Raman spectroscopy since new low-frequency lines are activated in the AFE phase due to the Brillouin zone-folding effect, typical for the modulated phases. The presence of the AFE phase between the FE and PE phases and the complex nature of tetragonal tungsten bronze crystal structure can explain the large thermal hysteresis observed at the FE-AFE transition between heating and cooling cycle and the strong depression of the Curie-Weiss temperature T{sub 0}. The semi-phenomenological Ising-like model based on the obtained experimental data is proposed to account for the observed FE-AFE-PE transition sequence.

  8. Superconductivity and crystal structural origins of the metal-insulator transition in Ba6 -xSrxNb10O30 tetragonal tungsten bronzes

    Science.gov (United States)

    Kolodiaznyi, Taras; Sakurai, Hiroya; Isobe, Masaaki; Matsushita, Yoshitaka; Forbes, Scott; Mozharivskyj, Yurij; Munsie, Timothy J. S.; Luke, Graeme M.; Gurak, Mary; Clarke, David R.

    2015-12-01

    Ba6 -xSrxNb10O30 solid solution with 0 ≤ x ≤6 forms the filled tetragonal tungsten bronze (TTB) structure. The Ba-end member crystallizes in the highest symmetry P 4 /m b m space group (a =b =12.5842 (18 )Å and c =3.9995 (8 )Å ) and so do all the compositions with 0 ≤ x ≤5 . The Sr-end member of the solid solution crystallizes in the tentatively assigned A m a m space group (a *=17.506 (4 )Å , b *=34.932 (7 )Å , and c *=7.7777 (2 )Å ). The latter space group is related to the parent P 4 /m b m TTB structure as a * ≈ √{2 }a ,b * ≈2 √{2 }a ,c *=2 c . Low-temperature specific heat measurements indicate that the Ba-rich compositions with x ≤2 are conventional BCS superconductors with TC ≤1.6 K and superconducting energy gaps of ≤0.38 meV. The values of the TC in the cation-filled Nb-based TTBs reported here are comparable with those of the unfilled KxWO3 and NaxWO3 TTBs having large alkali ion deficiency. As the unit cell volume decreases with increasing x , an unexpected metal-insulator transition (MIT) in Ba6 -xSrxNb10O30 occurs at x ≥3 . We discuss the possible origins of the MIT in terms of the carrier concentration, symmetry break, and Anderson localization.

  9. Facile fabrication of high-efficiency near-infrared absorption film with tungsten bronze nanoparticle dense layer

    Science.gov (United States)

    Lee, Seong Yun; Kim, Jae Young; Lee, Jun Young; Song, Ho Jun; Lee, Sangkug; Choi, Kyung Ho; Shin, Gyojic

    2014-06-01

    An excellent transparent film with effective absorption property in near-infrared (NIR) region based on cesium-doped tungsten oxide nanoparticles was fabricated using a facile double layer coating method via the theoretical considerations. The optical performance was evaluated; the double layer-coated film exhibited 10% transmittance at 1,000 nm in the NIR region and over 80% transmittance at 550 nm in the visible region. To optimize the selectivity, the optical spectrum of this film was correlated with a theoretical model by combining the contributions of the Mie-Gans absorption-based localized surface plasmon resonance and reflections by the interfaces of the heterogeneous layers and the nanoparticles in the film. Through comparison of the composite and double layer coating method, the difference of the nanoscale distances between nanoparticles in each layer was significantly revealed. It is worth noting that the nanodistance between the nanoparticles decreased in the double layer film, which enhanced the optical properties of the film, yielding a haze value of 1% or less without any additional process. These results are very attractive for the nanocomposite coating process, which would lead to industrial fields of NIR shielding and thermo-medical applications.

  10. Superconductivity in the Tungsten Bronzes

    Science.gov (United States)

    Wu, Phillip; Ishii, Satoshi; Tanabe, Kenji; Munakata, Ko; Hammond, Robert H.; Tokiwa, Kazuyasu; Geballe, Theodore H.; Beasley, Malcolm R.

    2015-03-01

    Via pulsed laser deposition and post-annealing, high quality K-doped WO3-y films with reproducible transport properties are obtained. A home built two-coil mutual inductance setup is used to probe the behavior of the films in the superconducting and normal state. The inverse penetration depths and dissipation peaks are measured as a function of temperature and field. Separately, via thin film deposition techniques, we report for the first time stable crystalline hexagonal WO3 on substrates. In order to tune the physical properties of the undoped material, we utilized an ionic liquid gating technique. We observe an insulator-to-metal transition, showing the ionic liquid gate to be a viable technique to alter the electrical transport properties of this material. By comparing the alkali and ionic liquid gated WO3, we conclude with some remarks regarding how superconductivity arises in this system.

  11. β-NbPO 5 and β-TaPO 5: Bronzoïds, second members of the monophosphate tungsten bronze series (PO 2) 4(WO 3) 2 m

    Science.gov (United States)

    Chahboun, H.; Groult, D.; Hervieu, M.; Raveau, B.

    1986-12-01

    The oxides β-NbPO 5 and β-TaPO 5 have been studied by X-ray diffraction and high resolution electron microscopy. They exhibit different supercells based on an orthorhombic subcell with the parameters a0 = 11.27 Å, b0 = 5.28 Å, c0 = 6.62 Å. It is shown that their framework corresponds to the member m = 2 of the series of monophosphate tungsten bronzes (PO 2) 4(WO 3) 2 m with pentagonal tunnels (MPTB P). The structure can thus be described as built up from ReO 3-type slabs which are two octahedra wide and connected through phosphate planes. The stability of these bronzoïds is discussed with respect to that of the MPTB P compounds. The relationships between the structures of the α and β forms of NbPO 5 and TaPO 5 are studied.

  12. Ion-exchange equilibria of tungsten in the ionite-sodium sulfate sulfuric acid solution system

    International Nuclear Information System (INIS)

    Ion-exchange equilibrium in the system macroporous ionite-Na2WO4-Na2SO4-H2O(H2SO4) are studied by the methods of IR- and absorption spectroscopy, electron microscopy and mercury porometry to develop methods for tungsten selective extraction from solutions mentioned. It is ascertained that amine-containing macroporous anionites features a high exchange capacity towards tungsten ions in sulfate solutions at pH 2.5-5.5. The anionites permit a complete separation of tungsten ions from sulfate ions and preparation of pure tungsten salts

  13. Solubility of tungstic acid and species of tungsten transfer in sodium chloride solutions at 25 Deg C

    International Nuclear Information System (INIS)

    Solubility of tungstic acid at room temperature in aqueous solutions with different content of Na+ and Cl- ions in pH range from 0.1 to 7.3 was determined using data of colorimetric analysis. It was ascertained that tungstic acid solubility increases with pH growth and increase in sodium content. Thermodynamic equilibrium constants for diverse tungsten-containing species existing in the solution at 3.5< pH<6 were calculated on the basis of experimental data. Dissociation and complexing reactions constants of tungstic acid were estimated

  14. Plasmachemical preparation of lead-tungstate bronze

    Czech Academy of Sciences Publication Activity Database

    Brožek, Vlastimil; Janča, J.; Eliáš, M.

    Praha : MAXDORF,s.r.o, 2004, s. 13-14. ISBN 80-7345-032-1. [Joint Seminar Development in Material Science Research and Education/14th./. Lednice (CZ), 31.08.2004-03.09.2004] Institutional research plan: CEZ:AV0Z2043910 Keywords : tungsten bronzes, plasmachemical preparation, RF-discharge Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  15. Adsorption of Lanthanides by A{sub y}Mo{sub x}W{sub 1-x}O{sub 3} Hexagonal Tungsten Bronzes and Prospects for their Potential Use as Recyclable Inert Matrix Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Luca, Vittorio; Yang, Bin; Yaman, Ilkay; Griffith, Christopher S.; Scales, Nicholas; Sizgek, Erden [Australian Nuclear Science and Technology Organisation (ANSTO), Institute of Materials Engineering, New Illawarra Road, Lucas Heights, New South Wales, 2234 (Australia)

    2008-07-01

    The hexagonal tungsten bronze (HTB) based adsorbents of general formula A{sub y}M{sub x}W{sub 1-x}O{sub 3}.ZH{sub 2}O have been a particular focus of attention in our laboratory for some time. In the context of a potential partition and transmutation strategy our interest in these HTB materials has been stimulated by their particularly high affinity for lanthanide (LN) and minor actinide (MA). In addition to partitioning operations the materials can also be contemplated for mop-up and decontamination applications. With Cs{sup +} as the target species, HTBs can be converted to very effective waste form materials with performances comparable to the best Cs-containing ceramics such as hollandite. However, their excellent affinity for LNs and MAs suggest their use for MA recycling. When granular variants of the HTB adsorbents are loaded with LNs and are heated in air to relatively modest temperatures these elements preferentially partition into relatively soluble phases imbedded within a durable WO{sub 3} matrix. Since the LN-containing phase is relatively soluble, efficient recovery of the LNs or potentially MAs is feasible. This, together with potentially favorable irradiation properties, suggests they may have uses as recyclable inert matrix fuels. In this communication, we discuss LN and MA adsorption and thermal properties of HTB materials with variable x, as well as resistance to {gamma}-radiation and heavy ion bombardment. Finally, recoverability of the LNs is considered. (authors)

  16. Structural and relaxor-like dielectric properties of unfilled tungsten bronzes Ba5-5xSm5xTi5xNb10-5xO30

    Science.gov (United States)

    Wei, T.; Dong, Z.; Zhao, C. Z.; Guo, Y. Y.; Zhou, Q. J.; Li, Z. P.

    2016-03-01

    New unfilled tetragonal tungsten bronze (TTB) oxides, Ba5-5xSm5xTi5xNb10-5xO30 (BSTN-x), where 0.10 ≤ x ≤ 0.35, have been synthesized in this work. Their crystal structure was determined and analyzed based on Rietveld structural refinement. It is found that single TTB phase can be formed in a particular x range (i.e., 0.15 ≤ x ≤ 0.3) due to the competition interaction between tolerance factor and electronegativity difference. Furthermore, dielectric and ferroelectric results indicate that phase transitions and ferroelectric states are sensitive to x. Referring to the local chemistry, we suggest that the raise of vacancies at the A2-site compared with that of A1-site will intensely depress the normal ferroelectric phase and is in favor of relaxor ferroelectric state. Macroscopically, previous A-site size difference standpoint on fill TTB compounds cannot give a reasonable explanation about the variation of dielectric maximum temperature (Tm) for present BSTN-x compounds. Alternatively, tetragonality (c/a) is adopted which can well describe the variation of Tm in whole x range. In addition, one by one correspondence between tetragonality and electrical features can be found, and the compositions involving high c/a are usually stabilized in normal ferroelectric phase. It is believed that c/a is a more appropriate parameter to illustrate the variation of ferroelectric properties for unfilled TTB system.

  17. beta. -NbPO/sub 5/ and. beta. -TaPO/sub 5/: bronzoieds, second members of the monophosphate tungsten bronze series (PO/sub 2/)/sub 4/(WO/sub 3/)/sub 2m/

    Energy Technology Data Exchange (ETDEWEB)

    Chahboun, H.; Groult, D.; Hervieu, M.; Raveau, B.

    1986-12-01

    The oxides ..beta..-NbPO/sub 5/ and ..beta..-TaPO/sub 5/ have been studied by X-ray diffraction and high resolution electron microscopy. They exhibit different supercells based on an orthorhombic subcell with the parameters a/sub 0/ = 11.27 A, b/sub 0/ = 5.28 A, c/sub 0/ = 6.62 A. It is shown that their framework corresponds to the member m = 2 of the series of monophosphate tungsten bronzes (PO/sub 2/)/sub 4/(WO/sub 3/)/sub 2m/ with pentagonal tunnels (MPTB/sub P/). The structure can thus be described as built up from ReO/sub 3/-type slabs which are two octahedra wide and connected through phosphate planes. The stability of these bronzoieds is discussed with respect to that of the MPTB/sub P/ compounds. The relationships between the structures of the ..cap alpha.. and ..beta.. forms of NbPO/sub 5/ and TaPO/sub 5/ are studied.

  18. Direct determination of sodium, potassium, chromium and vanadium in biodiesel fuel by tungsten coil atomic emission spectrometry

    International Nuclear Information System (INIS)

    Graphical abstract: -- Highlights: •Direct analysis of biodiesel on a tungsten coil atomizer. •Determination of Na, K, Cr and V by tungsten coil atomic emission spectrometry. •Sample dilution with methanol or ethanol. •Ten-microliter sample aliquots and limits of detection between 20 and 90 μg kg−1. •Low consumption of reagents, samples and gases in a 140 s per run procedure. -- Abstract: High levels of sodium and potassium can be present in biodiesel fuel and contribute to corrosion, reduced performance and shorter engine lifetime. On the other hand, trace amounts of chromium and vanadium can increase the emission of pollutants during biodiesel combustion. Sample viscosity, immiscibility with aqueous solutions and high carbon content can compromise biodiesel analyzes. In this work, tungsten filaments extracted from microscope light bulbs are used to successively decompose biodiesel's organic matrix, and atomize and excite the analytes to determine sodium, potassium, chromium and vanadium by tungsten coil atomic emission spectrometry (WCAES). No sample preparation other than simple dilution in methanol or ethanol is required. Direct analysis of 10-μL sample aliquots using heating cycles with less than 150 s results in limits of detection (LOD) as low as 20, 70, 70 and 90 μg kg−1 for Na, K, Cr and V, respectively. The procedure's accuracy is checked by determining Na and K in a biodiesel reference sample and carrying out spike experiments for Cr and V. No statistically significant differences were observed between reference and determined values for all analytes at a 95% confidence level. The procedure was applied to three different biodiesel samples and concentrations between 6.08 and 95.6 mg kg−1 for Na and K, and between 0.22 and 0.43 mg kg−1 for V were obtained. The procedure is simple, fast and environmentally friendly. Small volumes of reagents, samples and gases are used and no residues are generated. Powers of detection are comparable to

  19. Tungsten Bronze Barium Neodymium Titanate (Ba6-3nNd8+2nTi18O54): An Intrinsic Nanostructured Material and Its Defect Distribution.

    Science.gov (United States)

    Azough, Feridoon; Cernik, Robert Joseph; Schaffer, Bernhard; Kepaptsoglou, Demie; Ramasse, Quentin Mathieu; Bigatti, Marco; Ali, Amir; MacLaren, Ian; Barthel, Juri; Molinari, Marco; Baran, Jakub Dominik; Parker, Stephen Charles; Freer, Robert

    2016-04-01

    We investigated the structure of the tungsten bronze barium neodymium titanates Ba6-3nNd8+2nTi18O54, which are exploited as microwave dielectric ceramics. They form a complex nanostructure, which resembles a nanofilm with stacking layers of ∼12 Å thickness. The synthesized samples of Ba6-3nNd8+2nTi18O54 (n = 0, 0.3, 0.4, 0.5) are characterized by pentagonal and tetragonal columns, where the A cations are distributed in three symmetrically inequivalent sites. Synchrotron X-ray diffraction and electron energy loss spectroscopy allowed for quantitative analysis of the site occupancy, which determines the defect distribution. This is corroborated by density functional theory calculations. Pentagonal columns are dominated by Ba, and tetragonal columns are dominated by Nd, although specific Nd sites exhibit significant concentrations of Ba. The data indicated significant elongation of the Ba columns in the pentagonal positions and of the Nd columns in tetragonal positions involving a zigzag arrangement of atoms along the b lattice direction. We found that the preferred Ba substitution occurs at Nd[3]/[4] followed by Nd[2] and Nd[1]/[5] sites, which is significantly different to that proposed in earlier studies. Our results on the Ba6-3nNd8+2nTi18O54 "perovskite" superstructure and its defect distribution are particularly valuable in those applications where the optimization of material properties of oxides is imperative; these include not only microwave ceramics but also thermoelectric materials, where the nanostructure and the distribution of the dopants will reduce the thermal conductivity. PMID:26998674

  20. Effect of lead fluoride incorporation on the structure and luminescence properties of tungsten sodium phosphate glasses

    Science.gov (United States)

    Nardi, Rachel Prado Russo Delorenzo; Braz, Celso Eduardo; de Camargo, Andrea S. S.; Ribeiro, Sidney J. L.; Rocha, Lucas A.; Cassanjes, Fábia Castro; Poirier, Gael

    2015-11-01

    Tungsten phosphate glasses are known to be promising materials for several applications in optics such as non linear optical properties, lower phonon energy or photochromic effects related with tungsten oxide incorporation inside the phosphate network. In this study, lead fluoride has been incorporated in a 60NaPO3-40WO3 glass composition according to the ternary molar compositions (100 - x)[0.6NaPO3-0.4WO3]-xPbF2 with x varying from 0 to 60 mol%. The structural changes as a function of composition were investigated by thermal analysis, UV-visible absorption, Raman spectroscopy, X-ray diffraction of the crystallized samples, and Eu3+ emission in the visible. While DSC analyzes points out a strong decrease in the glass network connectivity and higher crystallization tendency with increasing PbF2 contents, Raman spectra clearly identify a progressive incorporation of PbF2 in the phosphate network with the formation of terminal Psbnd F and Wsbnd F bonds. These results are also in agreement with the crystallization of β-PbF2 observed for the most lead fluoride concentrated samples. Investigation of Eu3+ emission data in the visible showed longer 5D0 excited state lifetime values and higher quantum efficiencies. These results are discussed in terms of the assumption of higher local symmetry around Eu3+ with increasing PbF2 contents.

  1. Structure, upconversion photoluminescence, and dielectric properties of Ho{sup 3+}- and Yb{sup 3+}-codoped tetragonal tungsten bronze Sr{sub 4}La{sub 2}Ti{sub 4}Nb{sub 6}O{sub 30}

    Energy Technology Data Exchange (ETDEWEB)

    Wei, T., E-mail: weitong.nju@gmail.com [College of Science, Civil Aviation University of China, Tianjin 300300 (China); Li, C.P. [School of Electronics Information Engineering, Tianjin Key Laboratory of Film Electronic & Communication Devices, Tianjin University of Technology, Tianjin 300384 (China); Zhou, Q.J.; Li, Z.P.; Li, P.; Wu, J.; Yang, X.F. [College of Science, Civil Aviation University of China, Tianjin 300300 (China)

    2015-04-15

    Highlights: • TTB-type SLTN: Ho-Ybx with space group P4/mbm was determined. • UC photoluminescence of SLTN: Ho-Ybx ceramics was first reported. • Bright UC green emission was observed at room temperature. • Two-photon energy transfer process was confirmed for the UC processes. • Temperature stability of dielectric permittivity was improved for SLTN: Ho-Ybx. - Abstract: Ho{sup 3+}- and Yb{sup 3+}-codoped Sr{sub 4}La{sub 2}Ti{sub 4}Nb{sub 6}O{sub 30} (Sr{sub 4}La{sub 1.94–x}Ho{sub 0.06}Yb{sub x}Ti{sub 4}Nb{sub 6}O{sub 30}, abbreviated as SLTN: Ho-Ybx) ceramics have been synthesized, and their structural, up-conversion (UC) photoluminescence, and dielectric properties have been carefully investigated. Through Rietveld structural refinement, SLTN: Ho-Ybx samples are determined as single tetragonal tungsten bronze (TTB) phase with space group P4/mbm in which larger Sr{sup 2+} ions fill the A{sub 2}-sites, relative smaller La{sup 3+}, Ho{sup 3+}, and Yb{sup 3+} ions occupy the A{sub 1}-sites, while Ti{sup 4+} and Nb{sup 4+} ions fill the B-sites. Under 980 nm near infrared (NIR) excitation, bright UC green emission, relatively weak red and near-infrared (NIR) emissions, originating from {sup 5}F{sub 4}/{sup 5}S{sub 2} → {sup 5}I{sub 8}, {sup 5}F{sub 5} → {sup 5}I{sub 8}, and {sup 5}F{sub 4}/{sup 5}S{sub 2} → {sup 5}I{sub 7} transitions of Ho{sup 3+} ions, are confirmed for SLTN: Ho-Ybx. Two-photon energy transfer process is proved through pumping laser power dependence of emission intensity measurement. Furthermore, the influence of Ho{sup 3+}- and Yb{sup 3+}- ions on the dielectric properties of SLTN: Ho-Ybx is also investigated and the temperature stability of dielectric permittivity is improved.

  2. Neutron diffraction study of the atomic structure of cubic sodium-tungsten bronze (Na{sub 0.69}WO{sub 3}) single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Isakov, I. V., E-mail: ngkolin48@mail.ru; Kalyukanov, A. I. [Karpov Institute of Physical Chemistry (Obninsk Branch) (Russian Federation); Volkov, V. L. [Institute of Solid-State Chemistry (Russian Federation); Ozerov, R. P.; Fykin, L. E. [Karpov Institute of Physical Chemistry (Obninsk Branch) (Russian Federation)

    2011-05-15

    The atomic structure of a single crystal of one of four Na{sub 0.69}WO{sub 3} phases, which exist below 293 K, has been refined from neutron diffraction data (WWR-c reactor at the Karpov Institute of Physical Chemistry, Obninsk Branch; {lambda} = 1.168 Angstrom-Sign ; {lambda}/2 contribution < 0.8%; sin{theta}/{lambda} {<=} 0.810; T = 288 K; crystal sphere Empty-Set = 4.4 mm; cubic unit cell with a = 7.672 Angstrom-Sign , sp. gr. Im3, z = 8, {mu} = 1.9 mm{sup -1}). The Na{sub 0.69}WO{sub 3} atomic structure has been refined (198 independent reflections) taking into account the anisotropy of thermal vibrations (R{sub w} = 4.0%). The stoichiometric coefficient Na(0.69) is also refined. A structural distortion is revealed, which is characterized by the displacement of oxygen atoms (0, 0.2609(2), 0.2391(2)) from the ideal perovskite positions (0, 1/4, 1/4); this displacement doubles the ideal perovskite lattice period. The oxygen displacements can be described as rotations of oxygen octahedra by 3.58 Degree-Sign around the [111] direction. The structure remains cubic because the octahedra rotations with respect to all three perovskite cubic axes are identical.

  3. Neutron diffraction study of the atomic structure of cubic sodium-tungsten bronze (Na0.69WO3) single crystal

    International Nuclear Information System (INIS)

    The atomic structure of a single crystal of one of four Na0.69WO3 phases, which exist below 293 K, has been refined from neutron diffraction data (WWR-c reactor at the Karpov Institute of Physical Chemistry, Obninsk Branch; λ = 1.168 Å; λ/2 contribution −1). The Na0.69WO3 atomic structure has been refined (198 independent reflections) taking into account the anisotropy of thermal vibrations (Rw = 4.0%). The stoichiometric coefficient Na(0.69) is also refined. A structural distortion is revealed, which is characterized by the displacement of oxygen atoms (0, 0.2609(2), 0.2391(2)) from the ideal perovskite positions (0, 1/4, 1/4); this displacement doubles the ideal perovskite lattice period. The oxygen displacements can be described as rotations of oxygen octahedra by 3.58° around the [111] direction. The structure remains cubic because the octahedra rotations with respect to all three perovskite cubic axes are identical.

  4. Bronze rainbow hologram mirrors

    Science.gov (United States)

    Dawson, P.

    2006-02-01

    This project draws on holographic embossing techniques, ancient artistic conventions of bronze mirror design and modelling and casting processes to accomplish portraiture of reflection. Laser scanning, 3D computer graphics and holographic imaging are employed to enable a permanent 3D static holographic image to appear integrated with the real-time moving reflection of a viewer's face in a polished bronze disc. The disc and the figure which holds it (caryatid) are cast in bronze from a lost wax model, a technique which has been used for millennia to make personal mirrors. The Caryatid form of bronze mirror which went through many permutations in ancient Egyptian, Greece and Rome shows a plethora of expressive figure poses ranging from sleek nudes to highly embellished multifigure arrangements. The prototype of this series was made for Australian choreographer Graeme Murphy, Artistic Director of the Sydney Dance Company. Each subsequent mirror will be unique in figure and holographic imagery as arranged between artist and subject. Conceptually this project references both the modern experience of viewing mirrors retrieved from ancient tombs, which due to deterioration of the surface no longer reflect, and the functioning of Chinese Magic mirrors, which have the ability to project a predetermined image. Inspired by the metaphorical potential of these mirrors, which do not reflect the immediate reality of the viewer, this bronze hologram mirror series enables each viewer to reflect upon himself or herself observing simultaneously the holographic image and their own partially obliterated reflection.

  5. Phase transitions and electrical characterizations of (K 0.5Na 0.5) 2x(Sr 0.6Ba 0.4) 5-xNb 10O 30 (KNSBN) ceramics with 'unfilled' and 'filled' tetragonal tungsten-bronze (TTB) crystal structure

    KAUST Repository

    Yao, Yingbang

    2012-12-01

    Alkali-doped strontium barium niobate (K 0.5Na 0.5) 2x(Sr 0.6Ba 0.4) 5-xNb 10O 30 (KNSBN) ceramics has been prepared by a conventional solid-state reaction method. The alkali-dopant concentration x has been varied from 0.24 to 1.15 so that the crystal structure was transformed from \\'unfilled\\' to \\'filled\\' tetragonal tungsten-bronze (TTB) structure. Apart from the change in the structural properties, the effects of the alkali-dopants on the phase transition as well as ferroelectric, piezoelectric and pyroelectric properties have also been investigated. Phase transitions have been studied in the temperature range of -200°C to 350°C. The origins of these phase transitions are discussed. The addition of the alkali-dopants enhances the ferroelectric, piezoelectric and pyroelectric properties of the KNSBN ceramics. Alkali-doping also favors abnormal grain growth and thus results in a porous microstructure, which might contribute to the enhancement of the pyroelectric performance. © 2012 Elsevier Ltd.

  6. Bronze Age Acrobats

    DEFF Research Database (Denmark)

    Iversen, Rune

    2014-01-01

    immaterial, ritual and cosmological exchange that characterized the second and early firstmillennium BC.Beliefs and ritual practices went hand in hand with the adoption of a series of elite items and an aristocratic lifestyle, thereby creating a unique and fascinating European Bronze Age....

  7. Precipitation and ion floatation of molybdenum, tungsten, copper, and cobalt compounds by cetyltrimethylammonium bromide and sodium diethyldithiocarbamate

    International Nuclear Information System (INIS)

    Experimental data are presented on application of ion-flotation in purification of low-concentration (less than 10-3 M) acid solutions from molybdenum, tungsten, copper and cobalt ions. Two collectors, i.e. DEDC and CTMAB have been tested, their optimal consumption is determined. It is shown that CTMAB provides for selective purification from Mo and W ions and allows foam product with little water on flotation in a column to be obtained. But the achieved residual W and Mo concentration of 20 to 10 mg/l require deeper finishing purification in order to meet a sanitary permissible limiting concentration value employing other methods. DEDC provides for sufficient purification from nonferrous metal ions but does not possess selectivity with respect to some metals. The obtained results have shown the possibility to apply ion-flotation in concentration of metal ions in foam product in the process of waste water purification with further finishing purification up to a sanitary permissible limiting concentration value. 14 refs.; 3 figs.; 1 tab

  8. Biospeciation of tungsten in the serum of diabetic and healthy rats treated with the antidiabetic agent sodium tungstate.

    Science.gov (United States)

    Gómez-Gómez, M Milagros; Rodríguez-Fariñas, Nuria; Cañas-Montalvo, Benito; Domínguez, Jorge; Guinovart, Joan; Cámara-Rica, Carmen

    2011-05-30

    It is known that oral administration of sodium tungstate preserves the pancreatic beta cell function in diabetic rats. Healthy and streptozotocin-induced diabetic rats were treated with sodium tungstate for one, three or six weeks, after which the species of W in serum, were analysed. An increase in serum W with treatment time was observed. After six weeks, the serum W concentration in diabetic rats (70 mg L(-1)) was about 4.6 times higher than in healthy specimens. This different behaviour was also observed for Cu accumulation, while the Zn pattern follows the contrary. The patterns observed in the retention of Cu and Zn may be attributable to a normalization of glycaemia. The speciation analysis of W was performed using 2D separations, including an immunoaffinity packing and a SEC (Size Exclusion Chromatography) column coupled to an ICP-MS (Inductively Coupled Plasma Mass Spectrometry) for elemental detection. Ultrafiltration data together with SEC-ICP-MS results proved that around 80% of serum W was bound to proteins, the diabetic rats registering a higher W content than their healthy counterparts. Most of the protein-bound W was due to a complex with albumin. An unknown protein with a molecular weight higher than 100 kDa was also found to bind a small amount of W (about 2%). MALDI-TOF (Matrix-Assisted Laser Desorption Ionization Time-of-Flight) analysis of the desalted and concentrated chromatographic fractions confirmed albumin as the main protein bound to tungstate in rat serum, while no binding to transferrin (Tf) was detected. The interaction between glutathione and W was also evaluated using standard solutions; however, the formation of complexes was not observed. The stability of the complexes between W and proteins when subjected to more stringent procedures, like those used in proteomic methodologies (denaturing with urea or SDS, boiling, sonication, acid media, reduction with β-mercaptoethanol (BME) or DTT (dithiotreitol) and alkylation with

  9. Resistivity anomalies of the diphosphate tungsten bronze Cs sub 1-x P sub 8 W sub 8 O sub 40 (x = 0-0. 46) and its partially substituted phases Cs sub x A sub y P sub 8 W sub 8 O sub 40 (A = Rb, Na) and CsP sub 8 W sub 8-x Mo sub x O sub 40 : Synthesis, physical property measurements, and band electronic structure calculations

    Energy Technology Data Exchange (ETDEWEB)

    Wang, E.; Greenblatt, M. (Rutgers, State Univ. of New Jersey, New Brunswick (USA)); Rachidi, I.E.I.; Canadell, E. (Universite de Paris-Sud, Orsay (France)); Whangbo, M.H. (North Carolina State Univ., Raleigh (USA))

    1989-06-14

    The cesium phosphate tungsten bronze CsP{sub 8}W{sub 8}O{sub 40} exhibits a resistivity hump at {approx} 160 K and a resistivity upturn at {approx} 24 K. To understand the origin of these anomalies, we prepared cesium-deficient phases, Cs{sub 1-x}P{sub 8}W{sub 8}O{sub 40}, and alkali-metal- and molybdenum-substituted phases, Cs{sub x}A{sub y}P{sub 8}W{sub 8}O{sub 40} (x + y > 1) and CsP{sub 8}W{sub 8-x}Mo{sub x}O{sub 40}, and measured their electrical resistivities and magnetic susceptibilities. Those results are interpreted on the basis of the tight-binding band electronic structures calculated for the W{sub 4}O{sub 18} chain and the P{sub 8}W{sub 8}O{sub 40} lattice. 11 refs., 7 figs., 4 tabs.

  10. Bronze (Âge du)

    OpenAIRE

    Camps, G.

    2012-01-01

    En un siècle et demi de recherche archéologique, l’Afrique du Nord a livré moins d’une trentaine d’armes ou d’instruments en cuivre ou en bronze qui soit parvenue à la connaissance des spécialistes. Comment expliquer cette carence ? La rareté des objets métalliques attribuables au Chalcolithique ou à l’Âge du bronze demeure l’un des problèmes non résolus de la Protohistoire maghrébine. Armes de cuivre ou de bronze 1. Hache de l’oued Akrech ; 2. Hache en cuivre du Kef el Baroud ; 3. Hache en ...

  11. Ancient Chinese Bronzes: Teacher's Packet.

    Science.gov (United States)

    Smithsonian Institution, Washington, DC. Arthur M. Sackler Gallery.

    The focus of this teacher's packet is the bronze vessels made for the kings and great families of the early Chinese dynasties between 1700 B.C. and 200 A.D. The materials in the guide are intended for use by teachers and students visiting the exhibition, "The Arts of China," at the Arthur M. Sackler Gallery of the Smithsonian Institution in…

  12. Bronze Statuettes in Roman Graves

    Directory of Open Access Journals (Sweden)

    Margherita Bolla

    2014-02-01

    Full Text Available This research follows the investigations about the relationship between bronze statuettes and contexts in Roman times, particularly explored by Annemarie Kaufmann-Heinimann. The rarity of bronze figures (human, divine and animals in Roman tombs of Imperial age has been repeatedly emphasized. The aim of the paper is the collection, not exhaustive, of evidences in funerary contexts, to determine their meaning. From a methodological point of view, it was necessary to exclude figurines placed in graves but with other originary functions and several bronzes whose finding in tombs is unreliable. This preliminary survey has given about eighty all-round bronzes from burials, distributed in different areas, both in the Empire and marginal. Considering the huge amount of Roman burials known today, the overall evidence is scarce but allows some observations; it is evident the pre-eminence of Venus and Mercury, gods which had a funerary role. There is also an attempt to find the reasons of the rarity of metal statuettes in the tombs of roman period.

  13. Process for the recovery of tungsten in a pure form from tungsten-containing materials

    International Nuclear Information System (INIS)

    A process is described for the recovery of tungsten from tungsten-containing materials which comprises the steps of (i) admixing the tungsten-containing material with a melt at a temperature of between 6800C and 7500C. The melt consists of a salt selected from the group consisting of sodium nitrate, sodium nitrite and mixtures thereof in a substantially stoichiometrical amount to the tungsten constituent of the tungsten-containing material. This is done to disintegrate the tungsten-containing material and to form sodium tungstate, cooling the melt, and leaching the cooled melt with water to obtain an aqueous solution of sodium tungstate; (ii) admixing a solution of calcium chloride with the aqueous solution of sodium tungstate at a temperature of between 400C and 950C to form a calcium tungstate precipitate and separating the calcium tungstate; (iii) admixing the calcium tungstate with a preheated concentrated hydrochloric acid solution to form a tungstic acid precipitate and a CaCl/sub 2/ solution having a concentration of between 80 g/l and 180 g/l free HCl and separating the tungstic acid precipitate and obtaining tungstic acid which is substantially free of calcium ions, and (iv) calcining the tungstic acid to convert it to tungstic oxide and reducing the tungstic oxide to form metallic tungsten

  14. Decorative layers on tin bronzes

    Directory of Open Access Journals (Sweden)

    Z. Konopka

    2010-10-01

    Full Text Available Decorative layers are decisive for aesthetic value of castings, therefore significant demands are raised towards such layers, e.g. pleasant durable colour, gloss, and smoothness. The work discusses the influence of the type of mechanical working applied to the surfaces of CuSn10 tin bronze castings on the quality and durability of a decorative coating. The scope of the work has included designing and manufacturing of cast samples of tin bronze, mechanical working of the surfaces in order to prepare them for applying coating layers,generating decorative layers as a result of chemical reactions, and the quality assessment and comparison of the obtained coating. Theassessment of thickness and continuity of the obtained decorative layers based on metallographic examinations has been presented.

  15. CONTINUOUS HORIZONTAL CASTING OF PIPE BRONZE BILLET

    Directory of Open Access Journals (Sweden)

    E. I. Marukovich

    2015-05-01

    Full Text Available An experimental and calculated thermal analysis of the continuous casting of bronze tube billets is developed. Calculated allowable thermal conditions of drawing for stable casting.

  16. New Research on Bronze Age Textile Production

    DEFF Research Database (Denmark)

    Andersson, Eva Birgitta; Mårtensson, Linda; Nosch, Marie-Louise Bech; Rahmstorf, Lorenz

    2008-01-01

    presentation of the results from the systematic tests with Bronze Age textile tools. results concerning mesurements of lenght and time consumed.......presentation of the results from the systematic tests with Bronze Age textile tools. results concerning mesurements of lenght and time consumed....

  17. The Bronze Age Smith as Individual

    DEFF Research Database (Denmark)

    Nørgaard, Heide Wrobel

    During 1550-1100 BC magnificent decorated bronze objects appear in grave and hoard finds in Northwest Europe. While investigating similarities in the decorative elements of bronze objects belonging to the female gender, it is possible to find traces of the production process. These distinctive fe...

  18. Population genomics of Bronze Age Eurasia

    DEFF Research Database (Denmark)

    Allentoft, Morten E.; Sikora, Martin; Sjögren, Karl-Göran;

    2015-01-01

    The Bronze Age of Eurasia (around 3000-1000 BC) was a period of major cultural changes. However, there is debate about whether these changes resulted from the circulation of ideas or from human migrations, potentially also facilitating the spread of languages and certain phenotypic traits. We...... structure in both Europe and Asia. Our findings are consistent with the hypothesized spread of Indo-European languages during the Early Bronze Age. We also demonstrate that light skin pigmentation in Europeans was already present at high frequency in the Bronze Age, but not lactose tolerance, indicating a...... more recent onset of positive selection on lactose tolerance than previously thought....

  19. Population genomics of Bronze Age Eurasia.

    Science.gov (United States)

    Allentoft, Morten E; Sikora, Martin; Sjögren, Karl-Göran; Rasmussen, Simon; Rasmussen, Morten; Stenderup, Jesper; Damgaard, Peter B; Schroeder, Hannes; Ahlström, Torbjörn; Vinner, Lasse; Malaspinas, Anna-Sapfo; Margaryan, Ashot; Higham, Tom; Chivall, David; Lynnerup, Niels; Harvig, Lise; Baron, Justyna; Della Casa, Philippe; Dąbrowski, Paweł; Duffy, Paul R; Ebel, Alexander V; Epimakhov, Andrey; Frei, Karin; Furmanek, Mirosław; Gralak, Tomasz; Gromov, Andrey; Gronkiewicz, Stanisław; Grupe, Gisela; Hajdu, Tamás; Jarysz, Radosław; Khartanovich, Valeri; Khokhlov, Alexandr; Kiss, Viktória; Kolář, Jan; Kriiska, Aivar; Lasak, Irena; Longhi, Cristina; McGlynn, George; Merkevicius, Algimantas; Merkyte, Inga; Metspalu, Mait; Mkrtchyan, Ruzan; Moiseyev, Vyacheslav; Paja, László; Pálfi, György; Pokutta, Dalia; Pospieszny, Łukasz; Price, T Douglas; Saag, Lehti; Sablin, Mikhail; Shishlina, Natalia; Smrčka, Václav; Soenov, Vasilii I; Szeverényi, Vajk; Tóth, Gusztáv; Trifanova, Synaru V; Varul, Liivi; Vicze, Magdolna; Yepiskoposyan, Levon; Zhitenev, Vladislav; Orlando, Ludovic; Sicheritz-Pontén, Thomas; Brunak, Søren; Nielsen, Rasmus; Kristiansen, Kristian; Willerslev, Eske

    2015-06-11

    The Bronze Age of Eurasia (around 3000-1000 BC) was a period of major cultural changes. However, there is debate about whether these changes resulted from the circulation of ideas or from human migrations, potentially also facilitating the spread of languages and certain phenotypic traits. We investigated this by using new, improved methods to sequence low-coverage genomes from 101 ancient humans from across Eurasia. We show that the Bronze Age was a highly dynamic period involving large-scale population migrations and replacements, responsible for shaping major parts of present-day demographic structure in both Europe and Asia. Our findings are consistent with the hypothesized spread of Indo-European languages during the Early Bronze Age. We also demonstrate that light skin pigmentation in Europeans was already present at high frequency in the Bronze Age, but not lactose tolerance, indicating a more recent onset of positive selection on lactose tolerance than previously thought. PMID:26062507

  20. The Bronze Age Smith as Individual

    OpenAIRE

    Nørgaard, Heide Wrobel

    2011-01-01

    During 1550-1100 BC magnificent decorated bronze objects appear in grave and hoard finds in Northwest Europe. While investigating similarities in the decorative elements of bronze objects belonging to the female gender, it is possible to find traces of the production process. These distinctive features can help to identify workshops and their sphere of influence. Sometimes these traces have the ability to give much more information than just indicate the crafting process of the object. Errors...

  1. Screen-printed platinum electrodes for measuring crevice corrosion: Nickel aluminium bronze as an example

    OpenAIRE

    Cranny, Andrew; Harris, Nick; Lewis, Adam; Nie, Menyang; Wharton, Julian; Wood, Robert; Stokes, Keith

    2010-01-01

    Screen-printed platinum electrodes were used to monitor crevice corrosion processes. The electrodes, printed on an inert alumina substrate, formed the bottom of an artificial crevice when mechanically clamped to a rectangular block of nickel-aluminium bronze (NAB). Cyclic differential pulse voltammetry was used to detect corrosion products over time whilst the assembly was immersed in a 3.5% by weight aqueous solution of sodium chloride. Cupric (Cu2+), ferric (Fe3+) and ferrous (Fe2+) ions we...

  2. Effects of dispersed sulfides in bronze under line contact conditions

    Directory of Open Access Journals (Sweden)

    Tomohiro Sato

    2016-03-01

    Full Text Available A sintered bronze system is applied to plane bearings with some lubricants. A bronze-based, sulfide-dispersed Cu alloy was developed via sintering. Sulfides had some functions, reduction of friction resistance, preventing scoring and seizure. Effects of the developed sulfide-containing bronze were investigated using a journal-type testing apparatus in wet conditions; results indicate that the developed bronze may have some anti-scoring properties.

  3. Nanoscale building blocks in a novel lithium arsenotungsten bronze: Synthesis and characterization

    International Nuclear Information System (INIS)

    We report on a novel compound Li3AsW7O25 obtained by solid-state reaction and characterized by diffraction and spectroscopic methods. The bronze-type compound crystallizes in the orthorhombic space group Pbca with a=724.38(3) pm, b=1008.15(4) pm, c=4906.16(17) pm and Z=8. The structure is built up by chains of WO6 octahedra interconnected by AsO4 tetrahedra and WO6 octahedra forming a polyhedral arrangement as seen in intergrowth tungsten bronzes. The X-ray single crystal structure refinement allows solving the complex arsenotungstate framework. The powder neutron diffraction data analysis locates the lithium atoms. Thermal analysis showed that Li3AsW7O25 is stable up to its melting at 1135(3) K followed by a decomposition at 1182(5) K. The Kubelka–Munk treatment of the UV–vis spectrum revealed a wide band gap in the range of 2.84–3.40 eV depending on the presumed electron transition type. - Graphical abstract: Crystal structure of Li3AsW7O25 showing different schematic components. - Highlights: • A report on a novel compound Li3AsW7O25 obtained by solid-state reaction. • Chains and nano-blocks of WO6 octahedra and AsO4 tetrahedra formed a structure like intergrowth tungsten bronzes. • X-ray diffraction allowed solving the complex arsenotungstate framework. • Powder neutron diffraction data analysis locates the lithium atoms. • UV–vis spectrum revealed the band-gap

  4. Bismuth bronze from machu picchu, peru.

    Science.gov (United States)

    Gordon, R B; Rutledge, J W

    1984-02-10

    The decorative bronze handle of a tumi excavated at the Inca city of Machu Picchu, Peru, contains 18 percent bismuth and appears to be the first known example of the use of bismuth with tin to make bronze. The alloy is not embrittled by the bismuth because the bismuth-rich constituent does not penetrate the grain boundaries of the matrix phase. The use of bismuth facilitates the duplex casting process by which the tumi was made and forms an alloy of unusual color. PMID:17749940

  5. Copper and bronze coating with molybdenite

    International Nuclear Information System (INIS)

    The conditions were studied for producing qualitative bronze self-lubricating composite electrochemical coatings (SCEC). The copper composite coatings have been produced from sulfate electrolyte used for copper plating. The bronze SCEC have been obtained from a bath of the composition: tin dichloride-35, copper chloride-40, pyrophosphoric potassium-490. The problem of the optimal planning of Cu-MoS2 composite coatings characteristics has been considered. The matrix of the experiments planning is given, as well as the test results and numerical solution of coefficients of regression equations. The hardness of the bronze SCEC is affected most of all by the concentration and acidity of the suspension, and least of all - by the bath temperature. The friction coefficient of the self-lubricating coatings coupled with brass depends to a greater extent on the temperature and concentration of the suspension. The highest decrease of the friction coefficient can be expected at the minimum value of the abovesaid technological factors. The transient electric conductivity of the couple undergoing friction in air depends mainly on the cathode current density and concentration of dispersion phase in the electrolyte used for bronze plating. With the increase in the suspension concentration (and, therefore, in the amount of MoS2 inclusions into the coatings) the antifriction properties of the SCEC enhance. The dispersion addition increases the transient electric conductivity of the contact, however this does not prevent SCEC from being used in electrocommutation devices

  6. 75 FR 14257 - Pricing for Bronze Medals

    Science.gov (United States)

    2010-03-24

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF THE TREASURY United States Mint Pricing for Bronze Medals AGENCY: United States Mint, Department of the Treasury. ACTION: Notice. SUMMARY: The United States Mint is announcing the price of the 1\\5/16\\- inch...

  7. Optical planar waveguide in sodium-doped calcium barium niobate crystals by carbon ion implantation

    International Nuclear Information System (INIS)

    There is great interest in niobate crystals which belong to the tetragonal tungsten bronze (TTB) families owing to their intriguing properties. As one representative of such crystals, CBN (calcium barium niobate) has attracted rapidly growing attention. Because it has a higher Curie temperature than SBN (strontium barium niobate), possesses outstanding ferroelectric and it possesses optical properties. In addition, doped with sodium, CBN will show a higher Curie temperature than pure CBN. We report on the fabrication and characterization of optical planar waveguide in x-cut sodium-doped calcium barium niobate crystal by using C ion implantation. The guided-mode properties at the wavelength of 633 and 1539 nm are investigated through prism-coupling measurements, respectively. By applying direct end-face coupling arrangement, the near-field optical intensity distribution of waveguide modes is measured at 633 nm. For comparison, the modal profile of the same guided mode is also numerically calculated by the finite difference beam-propagation method via computer software BeamPROP. The transmission spectra of the waveguide before and after ion implantation treatments were investigated also. Our experiment results reveal that the waveguide could propagate light with transverse magnetic polarized direction only and it is assumed that the polarization selectivity of CBN crystal may responsible for this phenomenon

  8. Tungsten filament fire

    Science.gov (United States)

    Ruiz, Michael J.; Perkins, James

    2016-05-01

    We safely remove the outer glass bulb from an incandescent lamp and burn up the tungsten filament after the glass is removed. This demonstration dramatically illustrates the necessity of a vacuum or inert gas for the environment surrounding the tungsten filament inside the bulb. Our approach has added historical importance since the incandescent light bulb is being replaced by compact fluorescent and LED lamps.

  9. Textbook tests with tungsten

    CERN Multimedia

    Barbara Warmbein

    2010-01-01

    CERN's linear collider detector group joins forces with CALICE in building the world's first tungsten hadronic calorimeter.   Hadronic calorimeter prototype made of tungsten for the linear collider detector being equipped with CALICE scintillators. In a hall for test beam experiments at CERN, next to the CLOUD climate experiment and an irradiation facility, sits a detector prototype that is in many ways a first. It's the first ever hadronic sandwich calorimeter (HCal) prototype made of tungsten. It's the first prototype for a detector for the Compact Linear Collider Study CLIC, developed by the linear collider detector R&D group (LCD group) at CERN. And it's the first piece of hardware that results directly from the cooperation between CLIC and ILC detector study groups. Now its makers are keen to see first particle showers in their detector. The tungsten calorimeter has just moved from a workshop at CERN, where it was assembled from finely polished tungsten squares and triangles, into the ...

  10. Late Bronze Age hoard studied by PIXE

    International Nuclear Information System (INIS)

    The hoards of metallic objects belonging to the Late European Bronze Age can be interpreted differently depending on the type, number and composition of the artefacts. PIXE analysis has been performed in nine items from the Hoard of Freixanda in Portugal comprising four socket axes, a palstave axe, a ring, a chisel, a dagger, and a casting debris. Besides the composition of the main matrix elements, that is Cu and Sn, the amount of trace elements of interest like, As, Pb, Ni, and Ag has been determined using this ion beam technique. The high tin content alloy and the high purity of the metals from the Freixanda hoard are characteristic of the Portuguese and Spanish Late Bronze Age metallurgy, supporting the idea of a regional production.

  11. Crystal nucleus formation on the cathode under conditions of supersaturation of melt by lower valent forms

    International Nuclear Information System (INIS)

    Nucleation on the cathode of sodium-tungsten bronzes forom the Na2WO4-WO3 melt, containing 40 mol.% WO3 is studied. It has been found that in the initial period the cathode deposition of sodium-tungsten bronze is preceeded by the formation of tungsten soluble lower reduced forms, the concentration of which can considerably exceed the equilibrium one because of excessive overstress of oxide bronze crystal nucleation. The polarization of cathode and change of its potential at the crystal nucleation of sodium-tungsten bronze and switching-off of the electrolysis current has been studied

  12. The thermal analysis and derivative bronzes cast to plaster moulds

    Directory of Open Access Journals (Sweden)

    B. Pisarek

    2009-07-01

    Full Text Available It plaster moulds gets casted the alloys of following metals: Al, Cu, Ag, Au in precise and artistic founding. The investigation of the crys-tallization of bronzes in hot plaster moulds the method of the thermal analysis and derivative (TDA was not realized out so far. Probe TDAg and tripod enabling the execution of measurements on inductive casting machine INDUTHERM-VC 500D were designed for this technology especially. It was confirmed that one the method TDA can identify the crystallization process of the bronze in hot plaster moulds. The investigations of the superficial distribution of the concentration of elements in the microstructure of the studied grades of the bronze on X-ray microanalizer were conducted. It results that they be subject to in bronze CuSn10-C (B10 and the CuSn5Zn5Pb5-C (B555 of strong microsegregation from conducted investigations: Pb, Sn and Sb. The single separates of intermetallic phase κ was identified in the bronze B10 rich first of all in Zn, Sn, Sb and Fe, and two intermetallic phase, one rich were identified in the bronze B555 first of all in Zn, Sb, (Nor, Fe and second rich in Sn, Sb, (Nor, Fe. The most homogeneous microstructure from the bronze CuAl10Fe5Ni5-C (BA1055 is characterizes among the studied grades of the bronze in the cast state.

  13. Corrosion of high-density sintered tungsten alloys. Part 1

    International Nuclear Information System (INIS)

    The corrosion behaviour of four tungsten alloys has been evaluated through weight loss measurements after total immersion in both distilled water insight into the mechanism of corrosion was afforded by an examination of the and 5% sodium chloride solutions. Some insight the mechanism of corrosion was afforded by using the Scanning Electron Microscopy and through an analysis of the corrosion products. Pure tungsten and all the alloys studied underwent corrosion during the tests, and in each case the rare of corrosion in sodium chloride solution was markedly less than that in distilled water. A 95% W, 3.5% Ni, 1.5% Fe alloy was found to be the most corrosion resistant of the alloys under the experimental conditions. Examination of the data shows that for each of the tests, copper as an alloying element accelerates corrosion of tungsten alloys. 9 refs., 7 tabs., 12 figs

  14. 77 FR 14600 - Pricing for 2012 Kennedy Half-Dollar Bags and Rolls, Bronze Medals, the First Spouse Bronze Medal...

    Science.gov (United States)

    2012-03-12

    ... United States Mint Pricing for 2012 Kennedy Half-Dollar Bags and Rolls, Bronze Medals, the First Spouse.... SUMMARY: The United States Mint is announcing 2012 pricing for Kennedy Half-Dollar bags and rolls, bronze..., Associate Director for Sales and Marketing; United States Mint; 801 9th Street NW., Washington, DC 20220;...

  15. Late Bronze Age Hoard studied by PIXE

    OpenAIRE

    Gutiérrez Neira, P. C.; Zucchiatti, A.; Montero-Ruiz, I.; Vilaça, R.; Bottaini, C.; Gener, M.; Climent-Font, A.

    2011-01-01

    The hoards of metallic objects belonging to the Late European Bronze Age can be interpreted differently depending on the type, number and composition of the artefacts. PIXE analysis has been performed in nine items from the Hoard of Freixanda in Portugal comprising 4 socket axes, a palstave axe, a ring, a chisel, a dagger, and a casting debris. Besides the composition of the main matrix elements, that is Cu and Sn, the amount of trace elements of interest like, As, Pb, Ni and A...

  16. Gold and Silver Inlaid Bronze Sheep

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Gold and silver inlaying is a metal processing technique popular during the Spring and Autumn Period (770-476 B. C.) and the Warring States Period (475-221 B. C.). Patterns on the surface of the bronze figure are chiselled out and gold and silver threads (which can be as thin as hair) are inlaid. Finally the whole figure is filed and polished resulting in a splendid artistic work highlighting the different colours of the three different kinds of metal. The artifact shown here was unearthed from Ningxia'...

  17. Russian meteorite Bronze Age (rock record)

    CERN Document Server

    Vodolazhskaya, Larisa

    2013-01-01

    This paper presents the results of a study of petroglyphs found in the quartzite grotto near the Skelnovsky small village in the Northern Black Sea in the South of Russia. The aim of the study was the analysis and interpretation of the Early Bronze Age petroglyphs using archaeoastronomical methods. The article presents a comparative analysis of Skelnovsky grotto ancient images and contemporary eyewitness accounts of the Sikhote-Alin meteorite fall and meteorite shower. Some petroglyphs were interpreted by us using ethnographic and folklore material. In this study, the magnetic declination for the geographical coordinates Skelnovsky farm was calculated, and the projection of the whole picture Skelnovskih petroglyphs on the topographical map of the area was built. The proposed location of the meteorite fall was determined with this projection. It is confirmed by satellite pictures, on which are the distinguishable terrain features, typical for the meteorite fall, are visible including the possible impact crater...

  18. The determination of tungsten and iron in ferrotungsten alloys by x-ray-fluorescence spectrometry

    International Nuclear Information System (INIS)

    An accurate and precise method for the determination of tungsten and iron in ferrotungsten alloys is described. Samples are prepared for analysis by fusion with sodium peroxide and sodium hydroxide in a zirconium crucible. The melt is leached in water and acidified with hydrochloric acid. The tungstic acid thus produced is brought into solution by formation of a complex with tartaric acid. Matrix correction and calibration are achieved by means of the single-standard calibration method, use being made of a reference solution for tungsten prepared from sodium tungstate and a reference solution for iron prepared from iron wire

  19. Stamps of New China Eastern Zhou Dynasty Bronzes

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    The State Postal Bureau’s latest set of special stamps for 2003 features Eastern Zhou Dynasty (770-256 B,C.) bronzes. This eight-stamp set is the third to feature this type of relic; a set issued in 1964 depicted bronzes from the Yin Dynasty (14th-11th century}, and one featuring Western Zhou Dynasty (11th century-771 B.C.) bronzes was released in 1982.The Eastern Zhou Dynasty followed the Western, and during this period, bronze vessel casting developed remarkably. Artifacts from this period include sacrificial vessels, musical instruments, utensils, weapons and tools.One of these pieces, a rectangular tray decorated with tortoise and fish patterns, dates back to the late Spring and Autumn Period

  20. The Czech lands and Austria in the Bronze Age

    Czech Academy of Sciences Publication Activity Database

    Jiráň, Luboš; Salaš, M.; Krenn-Leeb, A.

    Oxford: Oxford University Press, 2013 - (Fokkens, H.; Harding, A.), s. 787-812 ISBN 978-0-19-957286-1 Institutional support: RVO:67985912 Keywords : Bronze Age * Bohemia * Moravia * Austria Subject RIV: AC - Archeology, Anthropology, Ethnology

  1. Reversibility of the lithium-vanadium bronze structure when cycled

    International Nuclear Information System (INIS)

    The positive electrodes of the lithium secondary current sources, manufactured on the basis of the Li1+x V3O8 lithium-vanadium bronze, obtained through the alcoxotechnology, are studied. It is established, that in proportion to the lithium introduction the initial crystalline bronze renders amorphous, remaining a single-phase one. Increase in the x-lithifying rate leads practically to decrease in the α-parameters and increase in the b- and c-parameters of the bronze crystal lattice, whereby these changes are quite reversible by cycling. The obvious degradation of the electrode electrical parameters is not connected with irreversible structural changes and may be explained by formation of passive films on the surface of the particles of the lithium-vanadium bronze

  2. Separation of tungsten and rhenium on alumina

    Directory of Open Access Journals (Sweden)

    MILOVAN SM. STOILJKOVIC

    2004-09-01

    Full Text Available The conditions for the efficient separation of tungsten(VI and rhenium (VII on alumina were established. The distribution coefficients Kd for tungstate and perrhenate anions, as well as the separation factors a (a = KdWO42-/Kd ReO4- were determined using hydrochloric or nitric acid as the aqueous media. A solution of sodium chloride in the pH range 2–6 was also examined. Under all the tested experimental conditions, alumina is a much better adsorbent for tungsten than for rhenium. The obtained results indicated that the best separation of these two elements is achieved when 0.01– 0.1 mol dm-3 HCl or 1.0 mol dm-3 HNO3 are used as the aqueous media. If NaCl is used as the aqueous phase, the best separation is achieved with 0.20 mol dm-3 NaCl, pH 4–6. Under these experimental conditions, the breakthrough and saturation capacities of alumina for tungsten at pH 4 are 17 and 26 mg W/g Al2O3, respectively. With increasing pH, these values decrease. Thus, at pH 6 they are only 4 and 13 mg W/g Al2O3, respectively.

  3. Non-destructive analysis of archaeological bronzes by nuclear techniques

    International Nuclear Information System (INIS)

    This paper studies a method for overcoming the difficulty of corroded surfaces by means of nondestructive nuclear methods in the determination of the composition of archaeological bronzes. It consists of the combination of PIXE or XRF information with Gamma Ray Transmission (GRT) data. A wide range applicability of this combined method is established by comparison with profiles of concentrations along the bronzes' patina obtained by SEM-EDAX. (orig.)

  4. Reproducible nuclear reactions during interaction of deuterium with oxide tungsten bronze

    International Nuclear Information System (INIS)

    The possibility of essential increase of rate of carrying out nuclear reactions with participance of deuterium in solids representing solid electrolytes with cation-electronic conductivity has been shown in the paper. It is found out that strict maintenance of experiment parameters leads to completely qualitatively reproduced results: generation of neutrons and heat at introduction of deuterium into the system. (author)

  5. Monophosphate tungsten bronzes with pentagonal tunnels: reinvestigation through the peephole of the superspace

    Czech Academy of Sciences Publication Activity Database

    Pérez, O.; Elcoro, L.; Pérez-Mato, J. M.; Petříček, Václav

    2013-01-01

    Roč. 69, č. 2 (2013), s. 122-136. ISSN 0108-7681 Grant ostatní: AVČR(CZ) Praemium Academiae Institutional support: RVO:68378271 Keywords : superspace theory * crystal structure analysis Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.095, year: 2013

  6. Sodium Azide

    Science.gov (United States)

    ... Matters What's New A - Z Index Facts About Sodium Azide What sodium azide is Sodium azide is a rapidly acting, ... give people sufficient warning of the danger. Where sodium azide is found and how it is used ...

  7. Tungsten oxide nanowire synthesis from amorphous-like tungsten films.

    Science.gov (United States)

    Seelaboyina, Raghunandan

    2016-03-18

    A synthesis technique which can lead to direct integration of tungsten oxide nanowires onto silicon chips is essential for preparing various devices. The conversion of amorphous tungsten films deposited on silicon chips by pulsed layer deposition to nanowires by annealing is an apt method in that direction. This perspective discusses the ingenious features of the technique reported by Dellasega et al on the various aspects of tungsten oxide nanowire synthesis. PMID:26871521

  8. Wolfram versusTungsten

    Czech Academy of Sciences Publication Activity Database

    Dufek, V.; Brožek, Vlastimil; Šarman, L.

    Vol. 2. Shrewsbury , UK : EPMA Shrewsbury , 2007, s. 425-429. ISBN 978-1-899072-30-9. [International Powder Metallurgy Congress & Exhibition EURO PM 2007. Toulouse (FR), 15.10.2007-17.10.2007] R&D Projects: GA ČR(CZ) GA104/05/0540 Institutional research plan: CEZ:AV0Z20430508 Keywords : Wolfram * Tungsten * Elhuyar * Ercker * Mathesius * Agricola * Schelle Subject RIV: JG - Metallurgy

  9. Electrochemical testing of laser treated bronze surface

    Energy Technology Data Exchange (ETDEWEB)

    Yilbas, B.S., E-mail: bsyilbas@kfupm.edu.sa [Dept. of Mechanical Engineering, King Fahd University of Petroleum and Minerals (KFUPM), Dhahran 31261 (Saudi Arabia); Toor, Ihsan-ul-Haq; Malik, Jahanzaib; Patel, F. [Dept. of Mechanical Engineering, King Fahd University of Petroleum and Minerals (KFUPM), Dhahran 31261 (Saudi Arabia); Karatas, C. [Engineering Faculty, Hacettepe University, Ankara (Turkey)

    2013-06-25

    Highlights: ► Laser treated surface is free from asperities. ► Laser treated layer extends uniformly below the surface with a thickness in the order of 40 μm. ► Presence of Cu{sub 3}N nitrides is evident from X-ray diffractogram. ► Dendritic structure is formed below the surface due to relatively slower cooling rates as compared to that at the surface. ► The corrosion current density for the laser treated surface is much less than that of the as-received surface. -- Abstract: Electrochemical testing of laser treated bronze surface is carried out and corrosion resistance of the surface is assessed. Morphological and metallurgical changes in the laser treated layer are examined using scanning electron microscope, energy dispersive spectroscopy, and X-ray diffraction. The pit sites formed at the surface are analyzed using scanning electron microscope. It is found that laser treatment improves the corrosion resistance of the treated surface. Fine grains are formed in the surface region of the laser treated layer, which are attributed to the large cooling rates from the surface.

  10. Study of patina formation on bronze specimens

    International Nuclear Information System (INIS)

    In this study, bronze samples (94.059% Cu; 0.023% Zn; 0.077% Pb and 5.801% Sn, w/w) were exposed for 8 months to a marine atmosphere (splash zone) at Barra of Tijuca Beach, Rio de Janeiro. X-ray diffraction analysis (XRD) was used to identify the composition of the corrosion products formed on the samples. The electrochemical properties were analyzed using potential and electrochemical impedance measurements. These analyses and measurements were obtained from periodically removed samples, and compared to those exposed to laboratory tests (total and alternating immersion) in 10-2 mol L-1 NaCl solution. The corrosion potential results, allied to XRD analysis, showed that the chemical nature of the films obtained on the surface of the field test samples was very similar to that obtained in the alternating immersion test. The main products identified were cuprite and atacamite. However, the film formed during the total immersion (TI) test was primarily composed of cuprite with nantokite traces, which was not observed in either the field or in alternating tests. The electrochemical impedance measurements obtained in laboratory and field test samples showed the formation of films with a porous structure. The thermodynamic evaluation was also consistent with the corrosion products formed.

  11. Evaluation of Bio-field Treatment on Physical and Structural Properties of Bronze Powder

    OpenAIRE

    Mahendra Kumar Trivedi; Gopal Nayak; Rama Mohan Tallapragada

    2015-01-01

    Bronze, a copper-tin alloy, widely utilizing in manufacturing of gears, bearing, and packing technologies due to its versatile physical, mechanical, and chemical properties. The aim of the present work was to evaluate the effect of bio-field treatment on physical and structural properties of bronze powder. Bronze powder was divided into two samples, one served as control and the other sample was received bio-field treatment. Control and treated bronze samples were characterized using x-ray di...

  12. Evaluation of Biofield Treatment on Physical and Structural Properties of Bronze Powder

    OpenAIRE

    Trivedi, Mahendra; Nayak, Gopal

    2015-01-01

    Bronze, a copper-tin alloy, widely utilizing in manufacturing of gears, bearing, and packing technologies due to its versatile physical, mechanical, and chemical properties. The aim of the present work was to evaluate the effect of biofield treatment on physical and structural properties of bronze powder. Bronze powder was divided into two samples, one served as control and the other sample was received biofield treatment. Control and treated bronze samples were characterized using x-ray diff...

  13. Preparation of tungsten oxide

    Science.gov (United States)

    Bulian, Christopher J.; Dye, Robert C.; Son, Steven F.; Jorgensen, Betty S.; Perry, W. Lee

    2009-09-22

    Tungsten trioxide hydrate (WO.sub.3.H.sub.2O) was prepared from a precursor solution of ammonium paratungstate in concentrated aqueous hydrochloric acid. The precursor solution was rapidly added to water, resulting in the crash precipitation of a yellow white powder identified as WO.sub.3.H.sub.2O nanosized platelets by x-ray diffraction and scanning electron microscopy. Annealing of the powder at 200.degree. C. provided cubic phase WO.sub.3 nanopowder, and at 400.degree. C. provided WO.sub.3 nanopowder as a mixture of monoclinic and orthorhombic phases.

  14. Gas tungsten arc welder

    International Nuclear Information System (INIS)

    A welder for automated closure of fuel pins by a gas tungsten arc process in which a rotating length of cladding is positioned adjacent a welding electrode in a sealed enclosure. An independently movable grinder, co-axial with the electrode, is provided in the enclosure for refurbishing the used electrode between welds. The specification also discloses means for loading of the cladding with fuel pellets and for placement of reflectors, gas capsules and end caps. Gravity feed conveyor and inerting means are also described. (author)

  15. Prompt gamma-ray analysis of archaeological bronze

    International Nuclear Information System (INIS)

    Prompt γ-ray analysis using the internal monostandard method was applied to voluminous archaeological bronze mirrors produced in ancient China. Sn/Cu content ratios were determined nondestructively by this method. Furthermore, Au/Cu, As/Cu, and Sb/Cu content ratios were determined by means of measuring decay γ-rays emitted from radioactive nuclides produced within samples via (n,γ) reactions. It is clear that the Sn/Cu content ratios in bronze mirrors produced in the Sung era is smaller than in ones produced in between the Han and the Tung era. (author)

  16. Chisels in the italian Bronze Age: technological and typological aspects

    OpenAIRE

    Speciale, Claudia; Zanini, Alessandro

    2010-01-01

    Bronze chisels are tools used “à percussion posée”; this means they need a minimum length and some functional parts (tang, body, blade); they could have a handle of perishable material and they were used with a hammer to work wood, bronze and other materials. Chisels can be classified following their functional parts; the first element is the shape (rod or socketed chisel); the second one is body section; the third one is tang section. Chronology and distribution of every type were identified...

  17. Archaeological investigations of the Bronze Age village of Bagnara di Romagna (RA

    Directory of Open Access Journals (Sweden)

    Maurizio Cattani

    2014-12-01

    Full Text Available This paper summarizes the results of researches carried out in the area next to the modern village of Bagnara di Romagna (RA, where several evidences related to a Bronze Age settlement have been collected. Recently test trenches and surface collections allowed to retrieve bronze and ceramics dating from the Middle Bronze Age (phase BM2 to the Recent Bronze Age (phase BR2. The analysis of landscape and the palaeoenvironmental reconstruction complete the outline of the region of Imola, Faenza and Lugo during the Bronze Age where are well known the ancient settlements of Solarolo, via Ordiere, Monte Castellaccio end S. Giuliano di Toscanella.

  18. Tungsten oxide in polymer electrolyte fuel cell electrodes-A thin-film model electrode study

    Energy Technology Data Exchange (ETDEWEB)

    Wickman, Bjoern, E-mail: bjorn.wickman@chalmers.s [Competence Centre for Catalysis, Department of Applied Physics, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden); Wesselmark, Maria; Lagergren, Carina; Lindbergh, Goeran [Applied Electrochemistry, School of Chemical Science and Engineering, KTH, SE-100 44 Stockholm (Sweden)

    2011-10-30

    Highlights: > Platinum and tungsten oxide thin-film electrocatalysts. > Single cell fuel cell evaluation. > Hydrogen-tungsten bronze formation. > CO oxidation on platinum on tungsten oxide. - Abstract: Thin films of WO{sub x} and Pt on WO{sub x} were evaporated onto the microporous layer of a gas diffusion layer (GDL) and served as model electrodes in the polymer electrolyte fuel cell (PEFC) as well as in liquid electrolyte measurements. In order to study the effects of introducing WO{sub x} in PEFC electrodes, precise amounts of WO{sub x} (films ranging from 0 to 40 nm) with or without a top layer of Pt (3 nm) were prepared. The structure of the thin-film model electrodes was characterized by scanning electron microscopy and X-ray photoelectron spectroscopy prior to the electrochemical investigations. The electrodes were analyzed by cyclic voltammetry and the electrocatalytic activity for hydrogen oxidation reaction (HOR) and CO oxidation was examined. The impact of Nafion in the electrode structure was examined by comparing samples with and without Nafion solution sprayed onto the electrode. Fuel cell measurements showed an increased amount of hydrogen tungsten bronzes formed for increasing WO{sub x} thicknesses and that Pt affected the intercalation/deintercalation process, but not the total amount of bronzes. The oxidation of pre-adsorbed CO was shifted to lower potentials for WO{sub x} containing electrodes, suggesting that Pt-WO{sub x} is a more CO-tolerant catalyst than Pt. For the HOR, Pt on thicker films of WO{sub x} showed an increased limiting current, most likely originating from the increased electrochemically active surface area due to proton conductivity and hydrogen permeability in the WO{sub x} film. From measurements in liquid electrolyte it was seen that the system behaved very differently compared to the fuel cell measurements. This exemplifies the large differences between the liquid electrolyte and fuel cell systems. The thin-film model

  19. Tungsten-enhanced growth of Methanosphaera stadtmanae

    Directory of Open Access Journals (Sweden)

    Dridi Bédis

    2012-05-01

    Full Text Available Abstract Background The methanogenic Archaea Methanosphaera stadtmanae has been detected in the human gut microbiota by both culture and culture-independent methods. Its growth reaches an exponential phase after 5 to 7-day culture in medium 322 (10% vol. Our recent successful isolation of Methanomassiliicoccus luminyensis, a tungstate-selenite-requiring Archaea sharing similar metabolism characteristics with M. stadtmanae prompted us to study the effects of tungsten and selenium on M. stadtmanae growth. Findings Addition of 0.2 mg/L sodium tungstate to medium 322 yielded, 48 hours after inoculation, a growth rate equivalent to that obtained after 6 days with control culture as measured by methane monitoring and optical density measurement. Addition of 50 μg/mL sodium selenate had no effect on M. stadtmanae growth. Quantitative real-time PCRs targeting the M. stadtmanae 16S rRNA confirmed these data. Conclusions These data provide new information regarding the poorly known nutritional requirements of the human gut colonizing organismsM. stadtmanae. Adding sodium tungstate to basal medium may facilitate phenotypic characterization of this organism and additionally aid the isolation of new Archaeafrom complex host microbiota.

  20. Origin of the mysterious Yin-Shang bronzes in China indicated by lead isotopes

    Science.gov (United States)

    Sun, Wei-Dong; Zhang, Li-Peng; Guo, Jia; Li, Cong-Ying; Jiang, Yu-Hang; Zartman, Robert E.; Zhang, Zhao-Feng

    2016-03-01

    Fine Yin-Shang bronzes containing lead with puzzlingly highly radiogenic isotopic compositions appeared suddenly in the alluvial plain of the Yellow River around 1400 BC. The Tongkuangyu copper deposit in central China is known to have lead isotopic compositions even more radiogenic and scattered than those of the Yin-Shang bronzes. Most of the Yin-Shang bronzes are tin-copper alloys with high lead contents. The low lead and tin concentrations, together with the less radiogenic lead isotopes of bronzes in an ancient smelting site nearby, however, exclude Tongkuangyu as the sole supplier of the Yin-Shang bronzes. Interestingly, tin ingots/prills and bronzes found in Africa also have highly radiogenic lead isotopes, but it remains mysterious as to how such African bronzes may have been transported to China. Nevertheless, these African bronzes are the only bronzes outside China so far reported that have lead isotopes similar to those of the Yin-Shang bronzes. All these radiogenic lead isotopes plot along ~2.0–2.5 Ga isochron lines, implying that deposits around Archean cratons are the most likely candidates for the sources. African cratons along the Nile and even micro-cratons in the Sahara desert may have similar lead signatures. These places were probably accessible by ancient civilizations, and thus are the most favorable suppliers of the bronzes.

  1. One-Step Synthesis of Titanium Oxyhydroxy-Fluoride Rods and Research on the Electrochemical Performance for Lithium-ion Batteries and Sodium-ion Batteries

    Science.gov (United States)

    Li, Biao; Gao, Zhan; Wang, Dake; Hao, Qiaoyan; Wang, Yan; Wang, Yongkun; Tang, Kaibin

    2015-10-01

    Titanium oxyhydroxy-fluoride, TiO0.9(OH)0.9F1.2 · 0.59H2O rods with a hexagonal tungsten bronze (HTB) structure, was synthesized via a facile one-step solvothermal method. The structure, morphology, and component of the products were characterized by X-ray powder diffraction (XRD), thermogravimetry (TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), ion chromatograph, energy-dispersive X-ray (EDX) analyses, and so on. Different rod morphologies which ranged from nanoscale to submicron scale were simply obtained by adjusting reaction conditions. With one-dimension channels for Li/Na intercalation/de-intercalation, the electrochemical performance of titanium oxyhydroxy-fluoride for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) was also studied. Electrochemical tests revealed that, for LIBs, titanium oxyhydroxy-fluoride exhibited a stabilized reversible capacity of 200 mAh g-1 at 25 mA g-1 up to 120 cycles in the electrode potential range of 3.0-1.2 V and 140 mAh g-1 at 250 mA g-1 up to 500 cycles, especially; for SIBs, a high capacity of 100 mAh g-1 was maintained at 25 mA g-1 after 115 cycles in the potential range of 2.9-0.5 V.

  2. Panetta Awarded Bronze Star for Afghanistan Intel Mission

    OpenAIRE

    Naval Postgraduate School Public Affairs Office

    2008-01-01

    Fellow officers in full dress uniform, family and friends ringed the room in rapt attention as Naval Reserve Lt. James Panetta was awarded the Bronze Star Medal by Naval Postgraduate School President Daniel Oliver in a special ceremony in the President's Conference Room, Dec. 9.

  3. Corrosion behavior of leaded-bronze alloys in sea water

    Energy Technology Data Exchange (ETDEWEB)

    Zohdy, K.M., E-mail: khalzohdy@yahoo.com [Higher Technological Institute, 10" t" h of Ramadan City (Egypt); Sadawy, M.M. [Mining and Petroleum Engineering Department, Al-Azhar University, Nasr City, Cairo 11371 (Egypt); Ghanem, M. [Industrial Education, Suez University (Egypt)

    2014-10-15

    The corrosion behavior of leaded-bronze alloys (Cu–5Sn–5Zn–5Pb, Cu–8Sn–8Zn–8Pb and Cu–10Sn–10Zn–10Pb) in sea water was investigated using weight loss method, open-circuit potential measurements (OCP), polarization techniques and electrochemical impedance spectroscopy (EIS). The nature and morphology of the corrosion products were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that the corrosion resistance decreases with decreasing copper content. The XRD indicated that the composition of patina depends on the concentration of Cu, Sn, Zn and Pb in each alloy. - Highlights: • The corrosion potential of leaded bronze shifts to more noble potential. • The corrosion resistance increases with increasing amount of copper content in leaded bronze alloys. • The patina formed on Cu–5Sn–5Zn–5Pb is more uniform and protective than other alloys. • The composition of patina formed on leaded bronze depends on the concentration of Cu, Sn, Zn and Pb in the alloy.

  4. Electrodeposited nanocrystalline bronze alloys as replacement for Ni

    NARCIS (Netherlands)

    Hovestad, A.; Tacken, R.A.; Mannetje, H.H.'t

    2008-01-01

    Nanocrystalline white-bronze, CuSn, electroplating was investigated as alternative to Ni plating as undercoat for noble metals in jewellery applications. A strongly acidic plating bath was developed with an organic additive to suppress hydrogen evolution and obtain bright coatings. Polarization curv

  5. Corrosion behavior of leaded-bronze alloys in sea water

    International Nuclear Information System (INIS)

    The corrosion behavior of leaded-bronze alloys (Cu–5Sn–5Zn–5Pb, Cu–8Sn–8Zn–8Pb and Cu–10Sn–10Zn–10Pb) in sea water was investigated using weight loss method, open-circuit potential measurements (OCP), polarization techniques and electrochemical impedance spectroscopy (EIS). The nature and morphology of the corrosion products were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that the corrosion resistance decreases with decreasing copper content. The XRD indicated that the composition of patina depends on the concentration of Cu, Sn, Zn and Pb in each alloy. - Highlights: • The corrosion potential of leaded bronze shifts to more noble potential. • The corrosion resistance increases with increasing amount of copper content in leaded bronze alloys. • The patina formed on Cu–5Sn–5Zn–5Pb is more uniform and protective than other alloys. • The composition of patina formed on leaded bronze depends on the concentration of Cu, Sn, Zn and Pb in the alloy

  6. Reporting Casting Bronze Plaque Becomes Advisers Class Project

    Science.gov (United States)

    Ross, Charlie

    1977-01-01

    Describes an advisers' class project (at the University of Oklahoma) which consisted of reporting on the casting of a bronze plaque bearing the names of the first school newspaper, "The Students Gazette," and its editor, Samuel M. Fox, for presentation in Philadelphia to commemorate scholastic journalism's Bicentennial. (MB)

  7. Neutron scattering material analysis of Bronze Age metal artefacts

    International Nuclear Information System (INIS)

    Non-destructive characterization of bronze artefacts from archaeological finds of the 'Terramare' dwellings near Modena, Italy, was carried out by time-of-flight neutron scattering at the ISIS spallation neutron source of the Rutherford Appleton Laboratory, UK. This provides information on ancient metal technology and its development through the Bronze Age in that region. Six pieces from three different classes as to use and manufacture, from the Middle to Late Bronze Age, were investigated on the ROTAX and GEM beam lines at ISIS, providing a comparison between results from the two instruments. A comparison is also made with three axes of the same area of provenance (Emilia, Terramare culture) from the Early, Middle and Late Bronze Age respectively, analysed previously. Data collected provide stable refinements of the phase fractions and lattice parameters by the Rietveld method, allowing determination of Sn contents from the unit cell expansion due to the incorporation of Sn into the Cu-type α-phase. Notably, two of the objects exhibit a range of Sn contents in the bulk as is evident from broad diffraction peaks (4-8 and 10-14 wt% Sn), while the other four artefacts have more defined Sn contents of 8, 9, 10 and 14.5 wt% respectively. The higher Sn weight fractions are associated with the presence of pure unalloyed Cu, interestingly coexisting in one case with two bronze phases (α and the eutectoid δ). One sample shows the presence of 2-3 wt% Pb. Varying amounts of oxidation products such as cuprite were identified. Texture information extracted from the diffraction data provided some indications of different working treatments of the analysed objects

  8. Deposition and Coating Properties on CVD Tungsten

    Institute of Scientific and Technical Information of China (English)

    DU Ji-hong; LI Zheng-xiang; LIU Gao-jian; ZHOU Hui-Huang; CHUN liang

    2004-01-01

    Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.

  9. Tungsten oxide thin films obtained by anodisation in low electrolyte concentration

    International Nuclear Information System (INIS)

    Tungsten oxide nanostructured films were grown on tungsten substrates by anodisation under a fixed voltage and with sodium fluoride as electrolyte. The effect of the anion chloride and the influence of the modifying agent disodium hydrogen phosphate in the tungsten oxide films were also investigated. The structural characterisation of the films was performed by scanning electron microscopy, atomic force microscopy and Raman spectroscopy. The band gap was determined through diffuse reflectance spectroscopy. The thin films were photoluminescent and emitted in the range of 300 to 630 nm when irradiated at 266 nm. The synthesised films efficiently degraded of methyl orange dye in the presence of hydrogen peroxide and 250 nm radiation. The modifying agent was responsible for the improvement of the photocatalytic activity. Films with similar photocatalytic performance were obtained when the system sodium fluoride and disodium hydrogen phosphate were replaced by sodium chloride. The porous structure and low band gap values were responsible for the photocatalytic behaviour. - Highlights: • Tungsten oxide thin films were obtained by anodisation of tungsten in aqueous media. • The performance of the NaCl, NaF and NaF/Na2HPO4 as electrolytes was investigated. • The relation between structure and optical behaviour has been discussed. • Films obtained with NaCl and NaF/Na2HPO4 present similar photocatalytic activity

  10. Tungsten oxide thin films obtained by anodisation in low electrolyte concentration

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Nadja B.D. da [Centro de Ciências Químicas, Farmacêuticas e de Alimentos, Universidade Federal de Pelotas, Campus Capão do Leão, s/n, Pelotas, RS (Brazil); Pazinato, Julia C.O. [Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500 Porto Alegre, RS (Brazil); Sombrio, Guilherme; Pereira, Marcelo B.; Boudinov, Henri [Instituto de Física, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500 Porto Alegre, RS (Brazil); Gündel, André; Moreira, Eduardo C. [Universidade Federal do Pampa, Travessa 45, 1650 Bagé, RS (Brazil); Garcia, Irene T.S., E-mail: irene.garcia@ufrgs.br [Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500 Porto Alegre, RS (Brazil)

    2015-03-02

    Tungsten oxide nanostructured films were grown on tungsten substrates by anodisation under a fixed voltage and with sodium fluoride as electrolyte. The effect of the anion chloride and the influence of the modifying agent disodium hydrogen phosphate in the tungsten oxide films were also investigated. The structural characterisation of the films was performed by scanning electron microscopy, atomic force microscopy and Raman spectroscopy. The band gap was determined through diffuse reflectance spectroscopy. The thin films were photoluminescent and emitted in the range of 300 to 630 nm when irradiated at 266 nm. The synthesised films efficiently degraded of methyl orange dye in the presence of hydrogen peroxide and 250 nm radiation. The modifying agent was responsible for the improvement of the photocatalytic activity. Films with similar photocatalytic performance were obtained when the system sodium fluoride and disodium hydrogen phosphate were replaced by sodium chloride. The porous structure and low band gap values were responsible for the photocatalytic behaviour. - Highlights: • Tungsten oxide thin films were obtained by anodisation of tungsten in aqueous media. • The performance of the NaCl, NaF and NaF/Na{sub 2}HPO{sub 4} as electrolytes was investigated. • The relation between structure and optical behaviour has been discussed. • Films obtained with NaCl and NaF/Na{sub 2}HPO{sub 4} present similar photocatalytic activity.

  11. Sodium Potassium Niobate Based Piezoelectric Ceramics

    OpenAIRE

    Wegrzyn, Margaret

    2012-01-01

    NKN doped samples, (100-x)NKN-xSBN (0 ≤ x ≤ 10) were produced using the conventional mixed oxide route with 0.45 wt% Fe2O3 sintering aid (xSBNF). After 20-24 hours mixing, samples were calcined at 850°C and sintered at 1100–1140°C (± 180°C/hour) for 4 hours. By XRD 4 mol% SBN was found to be the solubility limit for single phase structure. By SEM, second phases were visible when 2 ≤ x ≤ 4; their structure was subsequently shown to be tungsten bronze type (TBT). 2-4 SBNF samples were high d...

  12. Discovery of the Tungsten Isotopes

    OpenAIRE

    A. Fritsch; Ginepro, J. Q.; Heim, M.; Schuh, A.; SHORE, A.; Thoennessen, M

    2009-01-01

    Thirty-five tungsten isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  13. Method to manufacture tungsten carbide

    International Nuclear Information System (INIS)

    The patent deals with an improved method of manufacturing tungsten carbide. An oxide is preferably used as initial product whose particle size and effective surface approximately corresponds to that of the endproduct. The known methods for preparing the oxide are briefly given. Carbon monoxide is passed over the thus obtained oxide particles whereby the reaction mixture is heated to a temperature at which tungsten oxide and carbon monoxide react and tungsten carbide is formed, however, below that temperature at which the tungsten-containing materials are caked or sintered together. According to the method the reaction temperature is about below 9000C. The tungsten carbide produced has a particle size of under approximately 100 A and an active surface of about 20 m2/g. It has sofar not been possible with the usual methods to obtain such finely divided material with such a large surface. These particles may be converted back to the oxide by heating in air at low temperature without changing particle size and effective surface. One thus obtains a tungsten oxide with smaller particle size and larger effective surface than the initial product. (IHOE)

  14. Sodium Phosphate

    Science.gov (United States)

    Sodium phosphate is used in adults 18 years of age or older to empty the colon (large intestine, bowel) ... view of the walls of the colon. Sodium phosphate is in a class of medications called saline ...

  15. Sodium Oxybate

    Science.gov (United States)

    Sodium oxybate is used to prevent attacks of cataplexy (episodes of muscle weakness that begin suddenly and ... urge to sleep during daily activities, and cataplexy). Sodium oxybate is in a class of medications called ...

  16. Sodium Test

    Science.gov (United States)

    ... be limited. Home Visit Global Sites Search Help? Sodium Share this page: Was this page helpful? Also known as: Na Formal name: Sodium Related tests: Chloride , Bicarbonate , Potassium , Electrolytes , Osmolality , Basic ...

  17. Sodium Oxybate

    Science.gov (United States)

    ... sodium oxybate.Sodium oxybate is not available at retail pharmacies. A special program is in place to ... Drug Administration's (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by ...

  18. Characterization of bronzes by abrasive stripping voltammetry and thin layer chromatography

    OpenAIRE

    Komorsky-Lovrić, Šebojka; Horvat, Alka J.M.; Ivanković, Danijela

    2006-01-01

    Corrosion potentials of five samples of bronzes having different compositions and the stripping peak potentials of their main components were determined by abrasive stripping voltammetry. Using thin-layer chromatography in combination with electrochemical dissolution of bronzes in the two electrode sampler, the ions of tin, copper, lead and nickel were detected as the products of electro-oxidation of bronzes. It is shown that the dissolution of tin is preferential at low potential differences...

  19. Indirect TL dating of bronze with their thermoluminescent clay/sand--cores

    International Nuclear Information System (INIS)

    The occasional presence of thermoluminescent clay/sand core remains in bronze raises a possibility of dating them with the TL technique. In the dating of several bronze objects excavated in Shanxi Province, some satisfactory results have been achieved with dating accuracy between 8% and 12%. Since the sample collection does no harm to the bronze body, the TL dating technique can be more widely applied in the dating and authenticity tests

  20. Rewriting the Central European Early Bronze Age Chronology: Evidence from Large-Scale Radiocarbon Dating.

    Directory of Open Access Journals (Sweden)

    Philipp W Stockhammer

    Full Text Available The transition from the Neolithic to the Early Bronze Age in Central Europe has often been considered as a supra-regional uniform process, which led to the growing mastery of the new bronze technology. Since the 1920s, archaeologists have divided the Early Bronze Age into two chronological phases (Bronze A1 and A2, which were also seen as stages of technical progress. On the basis of the early radiocarbon dates from the cemetery of Singen, southern Germany, the beginning of the Early Bronze Age in Central Europe was originally dated around 2300/2200 BC and the transition to more complex casting techniques (i.e., Bronze A2 around 2000 BC. On the basis of 140 newly radiocarbon dated human remains from Final Neolithic, Early and Middle Bronze Age cemeteries south of Augsburg (Bavaria and a re-dating of ten graves from the cemetery of Singen, we propose a significantly different dating range, which forces us to re-think the traditional relative and absolute chronologies as well as the narrative of technical development. We are now able to date the beginning of the Early Bronze Age to around 2150 BC and its end to around 1700 BC. Moreover, there is no transition between Bronze (Bz A1 and Bronze (Bz A2, but a complete overlap between the type objects of the two phases from 1900-1700 BC. We thus present a revised chronology of the assumed diagnostic type objects of the Early Bronze Age and recommend a radiocarbon-based view on the development of the material culture. Finally, we propose that the traditional phases Bz A1 and Bz A2 do not represent a chronological sequence, but regionally different social phenomena connected to the willingness of local actors to appropriate the new bronze technology.

  1. The study of bronze statuettes with the help of neutron-imaging techniques

    OpenAIRE

    Van Langh, R.; Lehmann, E; Hartmann, S.; Kaestner, A.; Scholten, F.

    2009-01-01

    Until recently fabrication techniques of Renaissance bronzes have been studied only with the naked eye, microscopically, videoscopically and with X-radiography. These techniques provide information on production techniques, yet much important detail remains unclear. As part of an interdisciplinary study of Renaissance bronzes undertaken by the Rijksmuseum Amsterdam, neutron-imaging techniques have been applied with the aim of obtaining a better understanding of bronze workmanship during the R...

  2. Production and properties of bronze based cellular materials

    International Nuclear Information System (INIS)

    For production of lightweight components, cellular materials offer attractive potential. Here, manufacturing of sintered bodies from bronze hollow spheres is described. The process starts with fabrication of hollow copper particles by cementation of Cu on iron particles. The still fragile Cu shells are consolidated by coating with Sn and subsequent gravity sintering. The resulting specimens exhibit a closed cell bronze structure with rather consistent morphology and cell wall thickness. The apparent density may range between 1.5 and 3.0 gcm-3 and can be controlled by variation of particle size and wall thickness. The mechanical behavior of the structures esp. during compressive loading is described and related to the microstructural parameters. (author)

  3. Quantitative multiphase analysis of archaeological bronzes by neutron diffraction

    CERN Document Server

    Siano, S; Celli, M; Pini, R; Salimbeni, R; Zoppi, M; Kockelmann, W A; Iozzo, M; Miccio, M; Moze, O

    2002-01-01

    In this paper, we report the first investigation on the potentials of neutron diffraction to characterize archaeological bronze artifacts. The preliminary feasibility of phase and structural analysis was demonstrated on standardised specimens with a typical bronze alloy composition. These were realised through different hardening and annealing cycles, simulating possible ancient working techniques. The Bragg peak widths that resulted were strictly dependent on the working treatment, thus providing an important analytical element to investigate ancient making techniques. The diagnostic criteria developed on the standardised specimens were then applied to study two Etruscan museum pieces. Quantitative multiphase analysis by Rietveld refinement of the diffraction patterns was successfully demonstrated. Furthermore, the analysis of patterns associated with different artifact elements also yielded evidence for some peculiar perspective of the neutron diffraction diagnostics in archeometric applications. (orig.)

  4. Prevention of Dealloying in Manganese Aluminium Bronze Propeller: Part II

    OpenAIRE

    Napachat Tareelap; Kaysinee Sriraksasin; Nakorn Srisukhumbowornchai; Swieng Thuanboon; Choochat Nitipanyawong

    2014-01-01

    Due to the failure of manganese aluminium bronze (MAB) propeller caused by dealloying corrosion as described in Part I [1], this work aims to study the prevention of dealloying corrosion using aluminium and zinc sacrificial anodes. The results indicated that both of the sacrificial anodes could prevent the propeller from dealloying. Moreover, the dealloying in seawater was less than that found in brackish water. It was possible that hydroxide ions, from cathodic reaction, reacted with calcium...

  5. The Development of Iron Technology in the Mediterranean Bronze Age

    OpenAIRE

    Leek, Rodney Thomas

    2014-01-01

    In the eastern Mediterranean region in the Bronze Age there were a number of elite controlled, complex societies that through cultural activities and trade and international agreements, participated in a regional exchange economy. In the transition to Iron Age there was a confusing period with wars, migrations and the collapse of most of the elite societies,. At this time, iron technology had already spread to some parts of the region. When the regional economy collapsed in c. 1200 BC it crea...

  6. Tamil Chola Bronzes and Swamimalai Legacy: Metal Sources and Archaeotechnology

    Science.gov (United States)

    Srinivasan, Sharada

    2016-05-01

    This review explores the great copper alloy image casting traditions of southern India from archaeometallurgical and ethnometallurgical perspectives. The usefulness of lead isotope ratio and compositional analysis in the finger-printing and art historical study of more than 130 early historic, Pallava, Chola, later Chola, and Vijayanagara sculptures (fifth-eighteenth centuries) is highlighted, including Nataraja, Buddha, Parvati, and Rama images made of copper, leaded bronze, brass, and gilt copper. Image casting traditions at Swamimalai in Tamil Nadu are compared with artistic treatises and with the technical examination of medieval bronzes, throwing light on continuities and changes in foundry practices. Western Indian sources could be pinpointed for a couple of medieval images from lead isotope analysis. Slag and archaeometallurgical investigations suggest the exploitation of some copper and lead-silver sources in the Andhra and Karnataka regions in the early historic Satavahana period and point to probable copper sources for the medieval images in Karnataka, Tamil Nadu, and Andhra Pradesh. The general lower iron content in southern Indian bronzes perhaps renders the proximal copper-magnetite reserves of Seruvila in Sri Lanka as a less likely source. Given the lack of lead deposits in Sri Lanka, however, the match of the lead isotope signatures of a well-known Ceylonese Buddhist Tara in British Museum with a Buddha image from Nagapattinam in Tamil Nadu may underscore ties between the island nation and the southern Indian Tamil regions.

  7. Portable EDXRF investigation of the patinas on the Riace Bronzes

    Energy Technology Data Exchange (ETDEWEB)

    Buccolieri, Giovanni, E-mail: giovanni.buccolieri@unisalento.it [Università del Salento, Dipartimento di Matematica e Fisica, via Arnesano, 73100 Lecce (Italy); Buccolieri, Alessandro, E-mail: alessandro.buccolieri@unisalento.it [Università del Salento, Dipartimento di Scienze e Tecnologie Biologiche e Ambientali, via Monteroni, 73100 Lecce (Italy); Donati, Paola, E-mail: paola.donati@beniculturali.it [Istituto Superiore per la Conservazione e il Restauro, via di San Michele n. 23, 00153 Roma (Italy); Marabelli, Maurizio, E-mail: maurizio.marabelli@libero.it [Istituto Superiore per la Conservazione e il Restauro, via di San Michele n. 23, 00153 Roma (Italy); Castellano, Alfredo, E-mail: alfredo.castellano@unisalento.it [Università del Salento, Dipartimento di Matematica e Fisica, via Arnesano, 73100 Lecce (Italy)

    2015-01-15

    This paper summarizes the experimental results concerning the Energy Dispersive X-ray Fluorescence (EDXRF) analysis of patinas on two Riace Bronzes, kept in the National Archaeological Museum of Reggio Calabria (Calabria, Southern Italy). The two large Greek sculptures, famous nude bearded warriors both dated in the fifth century BC, are without a doubt, two masterpieces of inestimable historic and artistic value. EDXRF survey had the aim to determinate the chemical composition of the surface of these two bronze statues and to discriminate their different patinas. In particular, the concentration of sulphur, chlorine, tin, manganese, iron, copper, zinc and lead was determined by using a portable apparatus. Multivariate statistical analysis was carried out in order to identify possible correlations and/or differences of elemental composition among the patinas of these two statues. The information obtained made it possible to improve knowledge about the patinas of the Riace Bronzes, and this may help further studies and subsequent methods of restoration and/or of preservation of the two celebrated Greek sculptures.

  8. Portable EDXRF investigation of the patinas on the Riace Bronzes

    International Nuclear Information System (INIS)

    This paper summarizes the experimental results concerning the Energy Dispersive X-ray Fluorescence (EDXRF) analysis of patinas on two Riace Bronzes, kept in the National Archaeological Museum of Reggio Calabria (Calabria, Southern Italy). The two large Greek sculptures, famous nude bearded warriors both dated in the fifth century BC, are without a doubt, two masterpieces of inestimable historic and artistic value. EDXRF survey had the aim to determinate the chemical composition of the surface of these two bronze statues and to discriminate their different patinas. In particular, the concentration of sulphur, chlorine, tin, manganese, iron, copper, zinc and lead was determined by using a portable apparatus. Multivariate statistical analysis was carried out in order to identify possible correlations and/or differences of elemental composition among the patinas of these two statues. The information obtained made it possible to improve knowledge about the patinas of the Riace Bronzes, and this may help further studies and subsequent methods of restoration and/or of preservation of the two celebrated Greek sculptures

  9. Model of Cu-Al-Fe-Ni Bronze Crystallization

    Directory of Open Access Journals (Sweden)

    B. P. Pisarek

    2013-07-01

    Full Text Available According to the analysis of the current state of the knowledge shows that there is little information on the process of phase transformations that occur during the cooling Cu-Al-Fe-Ni hypo-eutectoid bronzes with additions of Cr, Mo and/or W, made additions individually or together, for the determination of: the type of crystallizing phases, crystallizing phases, order and place of their nucleation. On the basis of recorded using thermal and derivative analysis of thermal effects phases crystallization or their systems, analysis of the microstructure formed during crystallization - observed on the metallographic specimen casting ATD10-PŁ probe, analysis of the existing phase equilibrium diagrams forming elements tested Cu-Al-Fe-Ni bronze, with additions of Cr, Mo, W and/or Si developed an original model of crystallization and phase transformation in the solid state, the casting of high quality Cu-Al-Fe-Ni bronze comprising: crystallizing type phase, crystallizing phase sequence, place of nucleation.

  10. Tantalum and vanadium substitution in hexagonal K{sub 0.3}WO{sub 3} bronze. Synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Md. Shahidur; Murshed, M. Mangir; Gesing, Thorsten M. [Bremen Univ. (Germany). Chemische Kristallographie fester Stoffe; Baabe, Dirk [Technische Univ. Braunschweig (Germany). Inst. fuer Anorganische und Analytische Chemie

    2016-02-01

    Polycrystalline samples of tantalum and vanadium single and double substituted hexagonal potassium tungsten bronzes (K-HTB's) with nominal compositions of K{sub 0.3}(W{sup 6+}{sub 0.7}W{sup 5+}{sub 0.3-y}Ta{sup 5+}{sub y})O{sub 3} (0 ≤ y ≤ 0.3), K{sub 0.3}(W{sup 6+}{sub 0.7}W{sup 5+}{sub 0.3-y}V{sup 5+}{sub y})O{sub 3} (0 ≤ y ≤ 0.18) and K{sub 0.3}(W{sup 6+}{sub 0.7}W{sup 5+}{sub 0.3-y}Ta{sup 5+}{sub y/2}V{sup 5+}{sub y/2})O{sub 3} (0 ≤ y ≤ 0.3) were synthesized by solid state reactions in quartz tubes at 10{sup -7} MPa and 1073 K. The applied synthesis condition allowed K{sub 0.3}WO{sub 3} to crystallize in space group P6{sub 3}22, confirmed by X-ray powder diffraction and Raman spectroscopic analyses. In this K-HTB composition, W{sup 5+} could fully be replaced by Ta{sup 5+}, whereas V{sup 5+} could only be substituted up to y=0.16. The degree of W{sup 5+} substitution was explained in terms of second-order Jahn-Teller (SOJT) distortion of the d{sup 0} cations W{sup 6+}, Ta{sup 5+} and V{sup 5+}. The applied distortion index also demonstrates why a complete substitution of W{sup 5+} in K{sub 0.3}(W{sup 6+}W{sup 5+})O{sub 3} was allowed by a concomitant sharing of Ta{sup 5+} and V{sup 5+}, which are statistically distributed on the W{sup 5+}/W{sup 6+} sites. As W{sup 5+}(d{sup 1}) is not SOJT susceptible, it is also shown that the concentration of W{sup 5+} in tungsten bronzes plays an important role in the local WO{sub 6} octahedral symmetry as well as in its coordination.

  11. Information extraction from FN plots of tungsten microemitters

    International Nuclear Information System (INIS)

    Tungsten based microemitter tips have been prepared both clean and coated with dielectric materials. For clean tungsten tips, apex radii have been varied ranging from 25 to 500 nm. These tips were manufactured by electrochemical etching a 0.1 mm diameter high purity (99.95%) tungsten wire at the meniscus of two molar NaOH solution. Composite micro-emitters considered here are consisting of a tungsten core coated with different dielectric materials—such as magnesium oxide (MgO), sodium hydroxide (NaOH), tetracyanoethylene (TCNE), and zinc oxide (ZnO). It is worthwhile noting here, that the rather unconventional NaOH coating has shown several interesting properties. Various properties of these emitters were measured including current–voltage (IV) characteristics and the physical shape of the tips. A conventional field emission microscope (FEM) with a tip (cathode)–screen (anode) separation standardized at 10 mm was used to electrically characterize the electron emitters. The system was evacuated down to a base pressure of ∼10−8mbar when baked at up to ∼180°C overnight. This allowed measurements of typical field electron emission (FE) characteristics, namely the IV characteristics and the emission images on a conductive phosphorus screen (the anode). Mechanical characterization has been performed through a FEI scanning electron microscope (SEM). Within this work, the mentioned experimental results are connected to the theory for analyzing Fowler Nordheim (FN) plots. We compared and evaluated the data extracted from clean tungsten tips of different radii and determined deviations between the results of different extraction methods applied. In particular, we derived the apex radii of several clean and coated tungsten tips by both SEM imaging and analyzing FN plots. The aim of this analysis is to support the ongoing discussion on recently developed improvements of the theory for analyzing FN plots related to metal field electron emitters, which in particular

  12. Chemical characterization of CVD tungsten

    International Nuclear Information System (INIS)

    Characterization of tungsten films that have been deposited under ''selective'' conditions is presented. SEM and TEM studies indicate good conformal coverage and minimum encroachment. Cross section TEM results may indicate that some ''damage'' occurs at hole corners. Auger and SIMS depth profiles reveal very clean films. SIMS however does reveal that fluorine is a contaminant. Tungsten films were deposited at about 30A/min at 3000C with a 30/1 H/sub 2//WF/sub 6/ flow ration at 0.3 Torr. These films were selective up to film thicknesses of about 2000A. Mass spectral analysis of 99.8% WF/sub 6/ indicated no oxyfluorides and only a trace of methyl fluorosilanes that may have been an artifact of the gas sampling technique via contamination with silicone grease or lubricant. The sheet resistance of films became constant at about 8μ Ω-cm for film thicknesses (measured by profilometer after tungsten etch) greater than 4000A and increased up to about 20μ Ω-cm for very thin films (less than 500A). Auger depth profiling indicated that a thin oxide layer at the tungsten silicon interface corresponded to films having good adhesion as determined by a scribed tape pull test; where as a film deposited on a freshly HF cleaned surface with high carbon level had poor adhesion. Auger analysis indicated clean tungsten films with no evidence of fluorine. However, SIMS analysis indicated measurable levels of fluorine throughout the tungsten film and fluorine may be a significant contaminant as at higher temperatures it was found to have migrated to all interface areas as shown in SIMS study of annealed and unannealed W Six. The importance of fluorine impurities has not been correlated with any electrical properties

  13. Tungsten:Balance between Demand and Supply

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>In 2011,the tungsten market remained basically consistent with macro economic trends. In the first half of 2011, under the backdrop of upward economic situation,tungsten export and domestic consumption grew significantly and tungsten enterprises achieved remarkable economic benefits. However, as European debt crisis deepened in the second half of 2011, the global economic growth slowed down and

  14. Method of synthesizing tungsten nanoparticles

    Science.gov (United States)

    Thoma, Steven G; Anderson, Travis M

    2013-02-12

    A method to synthesize tungsten nanoparticles has been developed that enables synthesis of nanometer-scale, monodisperse particles that can be stabilized only by tetrahydrofuran. The method can be used at room temperature, is scalable, and the product concentrated by standard means. Since no additives or stabilizing surfactants are required, this method is particularly well suited for producing tungsten nanoparticles for dispersion in polymers. If complete dispersion is achieved due to the size of the nanoparticles, then the optical properties of the polymer can be largely maintained.

  15. Electrochemical behaviour of halide-oxide melts containing cryolite-molybdenum (tungsten) compositions and electrodeposition of molybdenum (tungsten) coatings

    International Nuclear Information System (INIS)

    A study is made into the influence of a fluoride-ion and fluoride complexes of fluoaluminate-ions on electrolytic reduction of molybdate and tungstate ions against the background of sodium chloride. These molten salts serve as a basis for electrodeposition of molybdenum and tungsten coatings. Solid coherent uniform dense coatings are produced at current density of 1 x 10-2 - 1.5 x 10-1 A/cm2 is up to 60-75 %, the thickness of coatings attains 150 μ

  16. The moessbauer spectroscopy study of an ancient bronze mirror without sampling

    International Nuclear Information System (INIS)

    The Moessbauer spectra of 119Sn for a bronze mirror of the Han Dynasty are described. A method of measuring Moessbauer spectrum without sampling is established. For the sake of contrast, both the spectra of transmission and of γ-ray scattering were measured. The results show that on the surface of the bronze mirror tin is in the state of Sn4+ oxide

  17. Metallography and microstructure interpretation of some archaeological tin bronze vessels from Iran

    International Nuclear Information System (INIS)

    Archaeological excavations in western Iran have recently revealed a significant Luristan Bronzes collection from Sangtarashan archaeological site. The site and its bronze collection are dated to Iron Age II/III of western Iran (10th–7th century BC) according to archaeological research. Alloy composition, microstructure and manufacturing technique of some sheet metal vessels are determined to reveal metallurgical processes in western Iran in the first millennium BC. Experimental analyses were carried out using Scanning Electron Microscopy–Energy Dispersive X-ray Spectroscopy and Optical Microscopy/Metallography methods. The results allowed reconstructing the manufacturing process of bronze vessels in Luristan. It proved that the samples have been manufactured with a binary copper–tin alloy with a variable tin content that may relates to the application of an uncontrolled procedure to make bronze alloy (e.g. co-smelting or cementation). The presence of elongated copper sulphide inclusions showed probable use of copper sulphide ores for metal production and smelting. Based on metallographic studies, a cycle of cold working and annealing was used to shape the bronze vessels. - Highlights: • Sangtarashan vessels are made by variable Cu-Sn alloys with some impurities. • Various compositions occurred due to applying uncontrolled smelting methods. • The microstructure represents thermo-mechanical process to shape bronze vessels. • In one case, the annealing didn’t remove the eutectoid remaining from casting. • The characteristics of the bronzes are similar to other Iron Age Luristan Bronzes

  18. Extraction Factor Of Pure Ammonium Paratungstate From Tungsten Scraps

    Directory of Open Access Journals (Sweden)

    Pee J.-H.

    2015-06-01

    Full Text Available Typical oxidation process of tungsten scraps was modified by the rotary kiln with oxygen burner to increase the oxidation rate of tungsten scraps. Also to accelerate the solubility of solid oxidized products, the hydrothermal reflux method was adapted. By heating tungsten scraps in rotary kiln with oxygen burner at around 900° for 2hrs, the scraps was oxidized completely. Then oxidized products (WO3 and CoWO4 was fully dissolved in the solution of NaOH by hydrothermal reflux method at 150° for 2hrs. The dissolution rate of oxidized products was increased with increasing the reaction temperature and concentration of NaOH. And then CaWO4 and H2WO4 could be generated from the aqueous sodium tungstate solution. Ammonium paratungstate (APT also could be produced from tungstic acid using by aqueous ammonium solution. The morphologies (cubic and plate types of APT was controlled by the stirring process of purified solution of ammonium paratungstate.

  19. Scintillating fiber ribbon --- tungsten calorimeter

    International Nuclear Information System (INIS)

    We describe an ultra-high density scintillating fiber and tungsten calorimeter used as an active beam-dump for electrons. Data showing the calorimeter response to electrons with momenta between 50 and 350 GeV/c are presented. 9 figs

  20. Desulfurization chemistry on tungsten surfaces

    International Nuclear Information System (INIS)

    Desulfurization on tungsten surfaces was studied by Auger spectroscopy, temperature programmed desorption, and infrared spectroscopy. Aliphatic compounds reacted by electrophilic interaction of sulfur with the surface. On sulfided surfaces adsorption occurred by disulfide linkages, but C-S bond scission required vacant metal sites. Thiophene underwent electrophilic attack on the ring at the α-carbon by metal sites

  1. Abrasive wear of BA1055 bronze with additives of Si, Cr, Mo and/or W

    Directory of Open Access Journals (Sweden)

    B. P. Pisarek

    2008-10-01

    Full Text Available Aluminium bronzes belong to the high-grade constructional materials applied on the put under strongly load pieces of machines, aboutgood sliding, resistant properties on corrosion both in the cast state how and after the thermal processing. It moves to them Cr and Si in the aim of the improvement of their usable proprieties. The additions Mo and/or W were not applied so far. It was worked out therefore the new kind of bronzes casting including these elements. Make additions to the Cu-Al-Fe-Ni bronze of Si, Cr, Mo and/or W in the rise of these properties makes possible. The investigations of the surface distribution of the concentration of elements in the microstructure of the studied bronze on X-ray microanalyzer were conducted. It results from conducted investigations, that in the aluminium bronze BA1055 after makes additions Si, Cr, Mo and/or W the phases of the type κFe, κNi crystallize, probably as complex silicides. Elements such as: Fe and Si dissolve first of all in phases κ, in smaller stage in the matrix of the bronze; Mn, Ni and W they dissolve in matrix and phases κ. It dissolves Cr and Mo in the larger stage in phases κ than in the matrix. The sizes of the abrasive wear were compared in the state cast multicomponentnew casting Cu-Al-Fe-Ni bronzes with the additives Cr, Mo or W with the wear of the bronze CuAl10Fe5Ni5Si. The investigations of thewear were conducted on the standard device. It results from conducted investigations, that make additions to bronze BA1055 of the additives of Si, Cr, Mo, and/or W it influences the rise of the hardness (HB of the bronze in the cast state, in the result of the enlarged quantity separates of hard phases κ, and in the consequence the decrease of the abrasive wear. The addition of molybdenum made possible obtainment of the microhardness of the phase α and γ 2 on the comparable level. From the microstructure of the bronze CuAl10Fe5Ni5MoSi is characterizes the smallest abrasive wear among

  2. Metallurgical and Chemical Characterization of Bronze Remains Found at the Houhe Site in Shanxi Province, China

    Science.gov (United States)

    Mu, D.; Nan, P. H.; Wang, J. Y.; Song, G. D.; Luo, W. G.

    2015-07-01

    This study attempts to determine the metallurgical and chemical characteristics of Chinese bronze artifacts from the early Iron Age by taking the bronze artifacts from the Houhe site as an example. The bronze artifacts included vessels, buckles, mirrors, and bells. Elemental compositions of 10 Chinese bronze artifacts from the Houhe site were determined by an x-ray fluorescence system. Microstructures were observed by a polarizing microscope. Most of the artifacts were cast and lacked external evidence of secondary processing. The copper content of the vessels is higher than the other samples, and the copper content of buckles is the lowest. High tin content is a distinctive characteristic of the mirrors. Through comparisons, bells show a decline in the content of copper from the Western Zhou dynasty to the early Han dynasty, and the content of lead increased over time. Combined with historical studies, the findings show that there may have been industrial standards for bronze production during the Han dynasty.

  3. Determining Foundry Area of Bronze Vessel Using REE in Clay Mould Residues

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The composition of casting clay core might provide clue to the foundry area of the bronze vessels. REE analysis of the residual clay mould was conducted by inductively coupled plasma atomic emission spectrometer (ICP-AES). Results reveal that characteristic of REE of clay mould from different region is dissimilar. It is feasible to restrict the possible foundry area of the bronze vessels on the basis of analysis of REE of clay mould residues on the bronzes. Meanwhile, this paper attempts to determine the foundry area of the bronze vessels unearthed at Jiuliandun tombs of Chu State, dated back to Warring States Period, in Zaoyang City, Hubei Province, and at Zuozhong cemetery, Spring and Autumn Period, in Jingmen City, Hubei Province. REE of clay core provides information on the foundry area of bronze vessels.

  4. Preliminary result on the analysis of Late Bronze Age metals

    International Nuclear Information System (INIS)

    Complete text of publication follows. The main event of the complex cultural changes during the transition from Middle to Late Bronze Age was the appearance of Tumulus culture in the Danube-Tisza region. In this period people rose mounds (tumuli) above their graves made from stone and soil. According to our present knowledge we believe that the ethnically inhomogeneous Tumulus culture was made homogenous by commerce (especially bronze commerce). Depots were typical of the final period of Middle Bronze Age called Koszider-phase. During the tumulus period the practice of hiding depots came to its end, bronze objects were put into graves. Therefore, it would be important to analyze the relation between the Koszider and Tumulus metallurgy. The main question to be answered is the following: were the trade connections and exchange of goods discontinued during the time of cultural changes? Examination of archaeological finds is carried out usually by typological methods which provide information on the attire fashion and funeral rite of cultures. The inherent capability of analytical techniques makes it possible to draw conclusions on the provenance of metals, thus facilitating to establish the contemporary trade routes. The metal finds from the southern part of the Great Hungarian Plain has not been investigated yet, though it would be important from the point of view of Tumulus culture. The main question is whether there is any noticeable change between the metallurgical craftsmanship of the consecutive eras. Therefore, it is important to determine the composition of the used raw materials, their sources, as well as the applied manufacturing technologies. For the characterization of archaeological bronze finds both conventional X-ray fluorescence (XRF) method and micro proton induced X-ray fluorescence (micro-PIXE) techniques are applied. The first one serves for the determination of the bulk composition of samples while the second one for the characterization of

  5. Chisels in the italian Bronze Age: technological and typological aspects

    Directory of Open Access Journals (Sweden)

    Speciale, Claudia

    2010-12-01

    Full Text Available Bronze chisels are tools used “à percussion posée”; this means they need a minimum length and some functional parts (tang, body, blade; they could have a handle of perishable material and they were used with a hammer to work wood, bronze and other materials. Chisels can be classified following their functional parts; the first element is the shape (rod or socketed chisel; the second one is body section; the third one is tang section. Chronology and distribution of every type were identified to obtain a general view of this class of tools during the Italian Bronze Age.

    Los cinceles de bronce son herramientas que se utilizan en percusión apoyada (à percussion posée, por consiguiente, necesitan una longitud mínima y algunas partes funcionales (empuñadura, cuerpo, hoja; podrían tener un mango de material perecedero. Se utilizan con un martillo en el labrado de la madera, del bronce y de otros materiales. Los cinceles se pueden clasificar de acuerdo con los siguientes elementos funcionales: el primero es la forma (cincel de varilla o de cubo; el segundo es la sección del cuerpo; el tercero es la sección de la empuñadura. La cronología y la distribución de cada tipo se identificaron para obtener una visión general de esta clase de instrumentos durante la Edad del Bronce en Italia.

  6. Hidden Sodium

    Centers for Disease Control (CDC) Podcasts

    2013-03-04

    In this podcast, learn about reducing sodium intake by knowing what to eat and the main sources of sodium in the diet. It's important for a healthy lifestyle.  Created: 3/4/2013 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 3/4/2013.

  7. Analysis of selective laser cleaning of patina on bronze coins

    Science.gov (United States)

    Buccolieri, G.; Nassisi, V.; Torrisi, L.; Buccolieri, A.; Castellano, A.; Di Giulio, M.; Giuffreda, E.; Delle Side, D.; Velardi, L.

    2014-04-01

    The patina, is the result of a large number of chemical, electrochemical and physical processes which occur spontaneously during interaction of metal surfaces with the environment. In this work we want to analyze and remove the patina in artefacts, exposed to atmosphere for various decades. Here, experimental results about the laser cleaning of bronze coins by KrF (248 nm) and Nd:YAG (532 nm) lasers are reported. Both laser wavelengths were efficient to reduce the chlorine concentration on the surface of the coins more than 80 %, as demonstrated by Energy Dispersive X-Ray Fluorescence analyses.

  8. Analysis of selective laser cleaning of patina on bronze coins

    International Nuclear Information System (INIS)

    The patina, is the result of a large number of chemical, electrochemical and physical processes which occur spontaneously during interaction of metal surfaces with the environment. In this work we want to analyze and remove the patina in artefacts, exposed to atmosphere for various decades. Here, experimental results about the laser cleaning of bronze coins by KrF (248 nm) and Nd:YAG (532 nm) lasers are reported. Both laser wavelengths were efficient to reduce the chlorine concentration on the surface of the coins more than 80 %, as demonstrated by Energy Dispersive X-Ray Fluorescence analyses.

  9. Investigation of laser cleaning on bronze cultural relics

    Science.gov (United States)

    Ling, Xiulan; Wang, Gao; Zhang, Chen

    2016-05-01

    The effects of laser cleaning on the corrosion layers of bronze cultural relics were studied using a pulsed fiber laser. The laser cleaning threshold value of the corrosion layers was obtained. It was found that the corrosion layer was removed successfully by employing a laser fluence value of 0.32 J cm-2 and scanning for three times. To obtain experimental evidence, laser con-focal scanning microscopy, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), laser induced breakdown spectroscopy (LIBS) and laser Raman spectroscopy were employed to investigate the cleaning efficiency of corrosion layers on specimens.

  10. Bronze analysis by k0-NAA and PIXE

    International Nuclear Information System (INIS)

    Five copper alloys were prepared with modern powder metallurgical processes in the frame of the European project 'Improvement of Means of Measurement on Archaeological Copper-Alloys for Characterisation and Conservation (IMMACO)' and certified for As, Pb, Sn and Zn mass fractions. Similar in their composition to archaeological bronze alloys, these Certified Reference Materials (CRMs) are to be used for calibration of XRF instruments for characterization of archaeological samples either in the laboratory or in the field. Successful contribution of non-destructive analytical methods (k0-NAA and PIXE) to the IMMACO project and to the certification of the five reference materials is presented. (author)

  11. Prevention of Dealloying in Manganese Aluminium Bronze Propeller: Part II

    Directory of Open Access Journals (Sweden)

    Napachat Tareelap

    2014-03-01

    Full Text Available Due to the failure of manganese aluminium bronze (MAB propeller caused by dealloying corrosion as described in Part I [1], this work aims to study the prevention of dealloying corrosion using aluminium and zinc sacrificial anodes. The results indicated that both of the sacrificial anodes could prevent the propeller from dealloying. Moreover, the dealloying in seawater was less than that found in brackish water. It was possible that hydroxide ions, from cathodic reaction, reacted with calcium in seawater to form calcium carbonate film protecting the propeller from corrosion.

  12. Dietary sodium

    DEFF Research Database (Denmark)

    Graudal, Niels

    2015-01-01

    The 2013 Institute of Medicine (IOM) report "Sodium Intake in Populations: Assessment of Evidence" did not support the current recommendations of the IOM and the American Heart Association (AHA) to reduce daily dietary sodium intake to below 2,300 mg. The report concluded that the population......-based health outcome evidence was not sufficient to define a safe upper intake level for sodium. Recent studies have extended this conclusion to show that a sodium intake below 2,300 mg/day is associated with increased mortality. In spite of this increasing body of evidence, the AHA, Centers for Disease...... Control (CDC), other public health advisory bodies, and major medical journals have continued to support the current policy of reducing dietary sodium....

  13. Tungsten oxide nanowires grown on amorphous-like tungsten films.

    Science.gov (United States)

    Dellasega, D; Pietralunga, S M; Pezzoli, A; Russo, V; Nasi, L; Conti, C; Vahid, M J; Tagliaferri, A; Passoni, M

    2015-09-11

    Tungsten oxide nanowires have been synthesized by vacuum annealing in the range 500-710 °C from amorphous-like tungsten films, deposited on a Si(100) substrate by pulsed laser deposition (PLD) in the presence of a He background pressure. The oxygen required for the nanowires formation is already adsorbed in the W matrix before annealing, its amount depending on deposition parameters. Nanowire crystalline phase and stoichiometry depend on annealing temperature, ranging from W18O49-Magneli phase to monoclinic WO3. Sufficiently long annealing induces the formation of micrometer-long nanowires, up to 3.6 μm with an aspect ratio up to 90. Oxide nanowire growth appears to be triggered by the crystallization of the underlying amorphous W film, promoting their synthesis at low temperatures. PMID:26292084

  14. Environmental roots of the late bronze age crisis.

    Science.gov (United States)

    Kaniewski, David; Van Campo, Elise; Guiot, Joël; Le Burel, Sabine; Otto, Thierry; Baeteman, Cecile

    2013-01-01

    The Late Bronze Age world of the Eastern Mediterranean, a rich linkage of Aegean, Egyptian, Syro-Palestinian, and Hittite civilizations, collapsed famously 3200 years ago and has remained one of the mysteries of the ancient world since the event's retrieval began in the late 19(th) century AD/CE. Iconic Egyptian bas-reliefs and graphic hieroglyphic and cuneiform texts portray the proximate cause of the collapse as the invasions of the "Peoples-of-the-Sea" at the Nile Delta, the Turkish coast, and down into the heartlands of Syria and Palestine where armies clashed, famine-ravaged cities abandoned, and countrysides depopulated. Here we report palaeoclimate data from Cyprus for the Late Bronze Age crisis, alongside a radiocarbon-based chronology integrating both archaeological and palaeoclimate proxies, which reveal the effects of abrupt climate change-driven famine and causal linkage with the Sea People invasions in Cyprus and Syria. The statistical analysis of proximate and ultimate features of the sequential collapse reveals the relationships of climate-driven famine, sea-borne-invasion, region-wide warfare, and politico-economic collapse, in whose wake new societies and new ideologies were created. PMID:23967146

  15. Environmental roots of the late bronze age crisis.

    Directory of Open Access Journals (Sweden)

    David Kaniewski

    Full Text Available The Late Bronze Age world of the Eastern Mediterranean, a rich linkage of Aegean, Egyptian, Syro-Palestinian, and Hittite civilizations, collapsed famously 3200 years ago and has remained one of the mysteries of the ancient world since the event's retrieval began in the late 19(th century AD/CE. Iconic Egyptian bas-reliefs and graphic hieroglyphic and cuneiform texts portray the proximate cause of the collapse as the invasions of the "Peoples-of-the-Sea" at the Nile Delta, the Turkish coast, and down into the heartlands of Syria and Palestine where armies clashed, famine-ravaged cities abandoned, and countrysides depopulated. Here we report palaeoclimate data from Cyprus for the Late Bronze Age crisis, alongside a radiocarbon-based chronology integrating both archaeological and palaeoclimate proxies, which reveal the effects of abrupt climate change-driven famine and causal linkage with the Sea People invasions in Cyprus and Syria. The statistical analysis of proximate and ultimate features of the sequential collapse reveals the relationships of climate-driven famine, sea-borne-invasion, region-wide warfare, and politico-economic collapse, in whose wake new societies and new ideologies were created.

  16. Corrosion characteristics of copper and leaded bronze in palm biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    Haseeb, A.S.M.A.; Masjuki, H.H.; Ann, L.J.; Fazal, M.A. [Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2010-03-15

    Biodiesel has become more attractive as alternative fuel for automobiles because of its environmental benefits and the fact that it is made from renewable sources. However, corrosion of metals in biodiesel is one of the concerns related to biodiesel compatibility issues. This study aims to characterize the corrosion behavior of commercial pure copper and leaded bronze commonly encountered in the automotive fuel system in diesel engine. Static immersion tests in B0, B50 and B100 fuels were carried out at room temperature for 2640 h. Similar immersion tests in B0, B100 and B100 (oxidized) fuels were also conducted at 60 C for 840 h. At the end of the test, corrosion behavior was investigated by weight loss measurements and changes in surface morphology. Fuels were analyzed by using TAN analyzer, FTIR, MOA (multi-element oil analyzer) to investigate acid concentration, oxidation level with water content and corrosive impurities respectively. Results showed that under the experimental conditions, pure copper was more susceptible to corrosion in biodiesel as compared to leaded bronze. (author)

  17. Thermodynamics of the hydrogen-carbon-oxygen-tungsten system, as applied to the manufacture of tungsten and tungsten carbide

    International Nuclear Information System (INIS)

    The thermodynamics of the quaternary hydrogen-carbon oxygen-tungsten system and its binary and ternary sub-systems are reviewed. Published thermodynamic data are evaluated, and expression for free energies of formation are chosen. These expressions are integrated with and equilibrium-calculating algorithm, producing a powerful tool for understanding and improving the manufacture of tungsten and tungsten carbide. Three examples are presented: reduction/carburization of tungstic oxide with hydrogen, carbon, and methane. (author)

  18. Synthesis of nanosized tungsten powder

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Nanosized tungsten powder was synthesized by means of different methods and under different conditions with nanosized WO3 powder. The powder and the intermediate products were characterized using XRD, SEM, TEM, BET (Brunauer Emmett Teller Procedure) and SAXS (X-ray diffracto-spectrometer/Kratky small angle scattering goniometer). The results show that nanosized WO3 can be completely reduced to WO2 at 600℃ after 40 min, and WO2 can be reduced to W at 700℃ after 90 min, moreover, the mean size of W particles is less than 40 nm. Furthermore, the process of WO3→WO2→W excelled that of WO3→W in getting stable nanosized tungsten powder with less grain size.

  19. Laser cleaning of tungsten ribbon

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Aniruddha, E-mail: nontee65@rediffmail.com [Advanced Fuel Fabrication Facility, Bhabha Atomic Research Centre, Tarapur, Maharashtra, 401504 (India); Sonar, V.R.; Das, D.K.; Bhatt, R.B.; Behere, P.G.; Afzal, Mohd.; Kumar, Arun [Advanced Fuel Fabrication Facility, Bhabha Atomic Research Centre, Tarapur, Maharashtra, 401504 (India); Nilaya, J.P.; Biswas, D.J. [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Trombay, 400085 (India)

    2014-07-01

    Removal of a thin oxide layer from a tungsten ribbon was achieved using the fundamental, second and third harmonic radiation from a Q- switched Nd-YAG laser. It was found that beyond the threshold, oxide removal was achieved at all wavelengths for a wide range of fluence values. The removal mechanism of the oxide layer was found to be critically dependent on both wavelength and fluence of the incident radiation and has been identified as ejection or sublimation. The un-cleaned and cleaned surfaces were analyzed by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS) and atomic force microscopy (AFM). Laser cleaned tungsten ribbons were used in a thermal ionization mass spectrometer (TIMS) to determine isotopic composition of Neodymium atoms.

  20. Laser cleaning of tungsten ribbon

    International Nuclear Information System (INIS)

    Removal of a thin oxide layer from a tungsten ribbon was achieved using the fundamental, second and third harmonic radiation from a Q- switched Nd-YAG laser. It was found that beyond the threshold, oxide removal was achieved at all wavelengths for a wide range of fluence values. The removal mechanism of the oxide layer was found to be critically dependent on both wavelength and fluence of the incident radiation and has been identified as ejection or sublimation. The un-cleaned and cleaned surfaces were analyzed by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS) and atomic force microscopy (AFM). Laser cleaned tungsten ribbons were used in a thermal ionization mass spectrometer (TIMS) to determine isotopic composition of Neodymium atoms.

  1. Fondaparinux sodium.

    Science.gov (United States)

    Keam, Susan J; Goa, Karen L

    2002-01-01

    black triangle Fondaparinux sodium, a selective factor Xa inhibitor, is the first in a new class of antithrombotics. It binds selectively with high affinity to antithrombin III and specifically catalyses the inactivation of factor Xa. The elimination half-life of fondaparinux sodium permits once daily treatment. black triangle A randomised, double-blind, parallel-group, dose-ranging, multicentre phase IIb study in 933 eligible patients established that a subcutaneous dose of between 1.5 and 3mg of fondaparinux sodium has the optimum efficacy and safety profile for prophylaxis of venous thromboembolism in patients undergoing major orthopaedic surgery. black triangle Fondaparinux sodium, given to more than 3600 patients undergoing major orthopaedic surgery who participated in prospective, randomised, double-blind, multicentre phase III clinical trials, significantly reduced the incidence of venous thromboembolism, with an overall risk reduction of 55.2% compared with enoxaparin. black triangle Fondaparinux sodium was well tolerated by patients undergoing major orthopaedic surgery, and at the recommended clinical dose of 2.5mg has a similar tolerability profile, including bleeding events, to standard enoxaparin regimens. Fondaparinux sodium has not been reported to cause antibody-induced thrombocytopenia. PMID:12109927

  2. Development and characterisation of a tungsten-fibre reinforced tungsten composite

    International Nuclear Information System (INIS)

    In tungsten-fibre reinforced tungsten, tungsten wire is combined with a tungsten matrix. The outstanding ductility of the fibres and extrinsic mechanisms of energy dissipation lead to an intense toughening. With extensive analytical and experimental investigations a manufacturing method based on chemical vapour infiltration is developed and first material is produced. The toughening mechanisms are shown by means of sophisticated mechanical experiments i.a. X-ray microtomography.

  3. Palaeoethnobotanical Data from the High Mountainous Early Bronze Age Settlement of Tsaghkasar-1 (Mt. Aragats, Armenia

    Directory of Open Access Journals (Sweden)

    Roman Hovsepyan

    2011-09-01

    Full Text Available Palaeoethnobotanical investigations suggest that at least part of the Early Bronze Age population of Tsaghkasar was settled and practiced agriculture in the high mountainous zone. People there appear to have cultivated hexa‐ and tetraploid wheats (probably bread wheat and emmer and barley (possibly hulled. Bronze Age agriculture in the Southern Caucasus differs from earlier and later period when cultivation of pulses, oil‐producing plants, and other plants was common. This emphasis on the cultivation and use of certain cereal grains at Early Bronze sites such as Tsaghkasar can tentatively be added to a constellation of practices associated with the Kura‐Araxes culture in the South Caucasus.

  4. Trapping and release of helium in tungsten

    OpenAIRE

    Lhuillier, Pierre-Emile; Belhabib, Taieb; Desgardin, Pierre; Courtois, Blandine; Sauvage, Thierry; Barthe, Marie-France; Thomann, Anne-Lise; Brault, Pascal; Tessier, Yves

    2011-01-01

    The behavior of tungsten under irradiation and helium implantation is a major stake of the materialrelated issues of fusion reactors. In this perspective the fate of helium in tungsten was studied by mean of several characterization techniques. The aim of this study is to highlight the trapping mechanisms of helium in tungsten and their correlation with implantation-induced defects. Helium was implanted into tungsten at two different energies, 0.32 and 60 keV. The helium was studied as a func...

  5. History of a Bronze Age tell and its environment

    Science.gov (United States)

    Kovács, Gabriella; Füleky, György; Vicze, Magdolna

    2016-04-01

    Százhalombatta-Földvár is the most excessively researched Bronze Age tell site in Hungary. Parallel to the investigation of the settlement structure and activity patterns the changes of the landscape and the effect of human alteration is also studied. Significant changes of the landscape can be detected from the Bronze Age until the recent natural and cultural heritage protection of the area. Archaeological, soil analytical and thin section soil micromorphological methods are used to reconstruct the past 4000 years of the tell and its immediate surroundings. Prior to the Bronze Age the area was covered by forest vegetation, so the initial settling could only be realised after deforestation (2000 BC). The result of the soil corings and the prepared soil thin sections are solid proves of this action. It also became evident that at some areas - so far it seems that at locales where house floors were laid for the very first time - even the topsoil was removed so intensively that only the B horizon of the relict forest soil can be found. This observation needs to be further tested outside the habitation area to define the horizontal extension of the forest clearance and the topsoil removal. The northern side of the settlement is bordered by a natural erosion gully. At 2000 BC it was just a natural depression, but by 1500 BC it was deepened to serve as a fortification ditch. Around 1200 BC the ditch started to be filled in and by 1000 BC it was refilled to such an extent that its surface was utilised again. At about 600 BC (Late Iron Age) a smaller inner rampart was erected on the southern side of the ditch for inner separation. Not much is known about the Roman period of this area (200 AD) but the remnants of a watchtower indicate their presence. During the 18th century AD the area was used for grape cultivation and later for hobby gardens up until the protection of the area in the late 20th century. Since then species of the original vegetation started to grow back

  6. A convenient thermal decomposition-co-reduction synthesis of nanocrystalline tungsten disilicide

    Indian Academy of Sciences (India)

    Jianhua Ma; Yihong Du; Yitai Qian

    2005-08-01

    Nanocrystalline WSi2 was synthesized by a thermal decomposition-co-reduction route via the reaction of anhydrous tungsten hexachloride and sodium fluorosilicate with metallic potassium in an autoclave at 650°C. X-ray powder diffraction pattern indicated that it was tetragonal WSi2. Transmission electron microscope image showed that it consisted of particles with an average diameter of about 50 nm. TGA and DTA indicated that it had good thermal stability below 600°C in air.

  7. LAMQS analysis applied to ancient Egyptian bronze coins

    Science.gov (United States)

    Torrisi, L.; Caridi, F.; Giuffrida, L.; Torrisi, A.; Mondio, G.; Serafino, T.; Caltabiano, M.; Castrizio, E. D.; Paniz, E.; Salici, A.

    2010-05-01

    Some Egyptian bronze coins, dated VI-VII sec A.D. are analyzed through different physical techniques in order to compare their composition and morphology and to identify their origin and the type of manufacture. The investigations have been performed by using micro-invasive analysis, such as Laser Ablation and Mass Quadrupole Spectrometry (LAMQS), X-ray Fluorescence (XRF), Laser Induced Breakdown Spectroscopy (LIBS), Electronic (SEM) and Optical Microscopy, Surface Profile Analysis (SPA) and density measurements. Results indicate that the coins have a similar bulk composition but significant differences have been evidenced due to different constituents of the patina, bulk alloy composition, isotopic ratios, density and surface morphology. The results are in agreement with the archaeological expectations, indicating that the coins have been produced in two different Egypt sites: Alexandria and Antinoupolis. A group of fake coins produced in Alexandria in the same historical period is also identified.

  8. Cavitation erosion behavior of nickel-aluminum bronze weldment

    Institute of Scientific and Technical Information of China (English)

    李小亚; 闫永贵; 许振明; 李建国

    2003-01-01

    Cavitation erosion behavior of nickel-aluminum bronze(NAB)weldment in 3.5% NaCl aqueous solution was studied by magnetostrictive vibratory device for cavitation erosion.The results show that cavitation erosion resistance of the weld zone(WZ)of the weldment is superior to that of the base metal.SEM observation of eroded specimens reveals that the phases undergoing selective attack by the stress of cavitation erosion at the early stage of cavitation erosion are:martensite in the WZ,α phase in the heat-affected zone(HAZ)and eutectoidal phase in the base metal; the microcracks causing cavitation damage initiate at the phase boundaries.

  9. Analysis of an ancient bronze statue by external beam pixe

    International Nuclear Information System (INIS)

    A quantitative analysis of an ancient Buddha statue was performed by external beam Proton Induced X-ray Emission for the purpose of identifying its originality. It is shown how the PIXE method can be applied for archeological study. The elemental composition of the statue is compared with that of several samples with definite ages. The experiment was performed by extracting 2.4 MeV proton beam through a 2 mm diameter collimator and 7.6 μm kapton foil to the He atmosphere. X-rays were measured by a Si(Li) detector. The analysed elements were Fe, Cu, Ag, Au and Hg for gold coating and Fe, Ni, Cu, Zn, As, Ag, Sn, Au, Pb and Bi for bronze body. (author) 11 refs.; 4 figs.; 2 tabs

  10. LAMQS analysis applied to ancient Egyptian bronze coins

    Energy Technology Data Exchange (ETDEWEB)

    Torrisi, L., E-mail: lorenzo.torrisi@unime.i [Dipartimento di Fisica dell' Universita di Messina, Salita Sperone, 31, 98166 Messina (Italy); Caridi, F.; Giuffrida, L.; Torrisi, A. [Dipartimento di Fisica dell' Universita di Messina, Salita Sperone, 31, 98166 Messina (Italy); Mondio, G.; Serafino, T. [Dipartimento di Fisica della Materia ed Ingegneria Elettronica dell' Universita di Messina, Salita Sperone, 31, 98166 Messina (Italy); Caltabiano, M.; Castrizio, E.D. [Dipartimento di Lettere e Filosofia dell' Universita di Messina, Polo Universitario dell' Annunziata, 98168 Messina (Italy); Paniz, E.; Salici, A. [Carabinieri, Reparto Investigazioni Scientifiche, S.S. 114, Km. 6, 400 Tremestieri, Messina (Italy)

    2010-05-15

    Some Egyptian bronze coins, dated VI-VII sec A.D. are analyzed through different physical techniques in order to compare their composition and morphology and to identify their origin and the type of manufacture. The investigations have been performed by using micro-invasive analysis, such as Laser Ablation and Mass Quadrupole Spectrometry (LAMQS), X-ray Fluorescence (XRF), Laser Induced Breakdown Spectroscopy (LIBS), Electronic (SEM) and Optical Microscopy, Surface Profile Analysis (SPA) and density measurements. Results indicate that the coins have a similar bulk composition but significant differences have been evidenced due to different constituents of the patina, bulk alloy composition, isotopic ratios, density and surface morphology. The results are in agreement with the archaeological expectations, indicating that the coins have been produced in two different Egypt sites: Alexandria and Antinoupolis. A group of fake coins produced in Alexandria in the same historical period is also identified.

  11. LAMQS analysis applied to ancient Egyptian bronze coins

    International Nuclear Information System (INIS)

    Some Egyptian bronze coins, dated VI-VII sec A.D. are analyzed through different physical techniques in order to compare their composition and morphology and to identify their origin and the type of manufacture. The investigations have been performed by using micro-invasive analysis, such as Laser Ablation and Mass Quadrupole Spectrometry (LAMQS), X-ray Fluorescence (XRF), Laser Induced Breakdown Spectroscopy (LIBS), Electronic (SEM) and Optical Microscopy, Surface Profile Analysis (SPA) and density measurements. Results indicate that the coins have a similar bulk composition but significant differences have been evidenced due to different constituents of the patina, bulk alloy composition, isotopic ratios, density and surface morphology. The results are in agreement with the archaeological expectations, indicating that the coins have been produced in two different Egypt sites: Alexandria and Antinoupolis. A group of fake coins produced in Alexandria in the same historical period is also identified.

  12. Spectrophotometric determination of beryllium in bronzes with chrome azurol S

    International Nuclear Information System (INIS)

    Some remarks on the spectrophotometric determination of beryllium in bronzes using Chrome Azurol S (CAS) are given. The determination was performed at pH=6.5 and 10.0 using hexamethylene-tetramine and ammoniacal buffers, respectively. It was demonstrated that the determination of Be with CAS at pH=10.0 is slightly less sensitive, but it has two advantages which are important in obtaining reliable results. First, is the shorter time to reach the equilibrium between Be and CAS, and second, is lower pH sensitivity so that a better precision of the results at pH=10.0 overcompensate the slightly lower sensitivity at this pH in comparison with that at pH=6.5. (Author)

  13. The Bronze "Ding of Flourishing Olympic "for the Main Stadium of the 2008 Olympic Games

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ The bronze "Ding of Flourishing Olympic" for the main stadium of the 2008Olympic Games has been completed by Yuda Group Company. The "Ding of Flourishing Olympic" was designed by Lanzhou Ludu Chunqiu Cultural Disseminating Co. Ltd.

  14. Synchrotron X-ray diffraction and imaging of ancient Chinese bronzes

    International Nuclear Information System (INIS)

    High-energy synchrotron X-ray diffraction and imaging experiments were performed at the Advanced Photon Source on two ancient Chinese bronzes from the Art Institute of Chicago with the goal to nondestructively study their microstructure. The first object, a bronze fragment from an early Western Zhou dynasty vessel (Hu, 11th/10th century B.C.), was investigated with spatially-resolved diffraction to reveal the depth and composition of the surface corrosion layer as well as the composition and grain size of the underlying bronze core. The second object, a bronze dagger-axe (Ge, 3rd/2nd century B.C.) with a silver-inlaid sheath, was studied under both diffraction and imaging conditions. It was found to have been cast as a single object, answering longstanding scholars' questions on whether the ceremonial object concealed an interior blade. (orig.)

  15. University receives 2009 Governor's Environmental Excellence Bronze Medal for Campus Tree Tour 2008 Event

    OpenAIRE

    West, Hilary

    2009-01-01

    Virginia Tech received the 2009 Governor's Environmental Excellence Bronze Medal in the Environmental Project (Government) category for hosting the Campus Tree Tour 2008 tree planting event in Blacksburg on Oct. 21, 2008.

  16. Influence Cr on Crystallization and the Phase Transformations of the Bronze BA1044

    Directory of Open Access Journals (Sweden)

    B. P. Pisarek

    2007-07-01

    Full Text Available The investigations were introduced in the paper, method of thermal and derivative analysis (TDA, the process of crystallization and phase transformation in the solid state of the aluminium bronze CuA110Fe4Ni4 (BA1044 and with the addition 0.3% Cr. Two intermetallic phase were identified in the microstructure of the bronze BA1044: κFel - rich in Fe and Cu and κFe2 - rich in Fe, and in the microstructure of the bronze BA1044+0.3 % Cr only one phase κFel - rich in Fe, Cu and Cr. The presence of chrome in the bronze BA1044 reduce size the primary crystals of the phase β, reduces the dynamics of the processes of thermal phase transformation in the solid state and lengthens the time their of duration.

  17. High-energy, high-rate consolidation of tungsten and tungsten-based composite powders

    Energy Technology Data Exchange (ETDEWEB)

    Raghunathan, S.K.; Persad, C.; Bourell, D.L.; Marcus, H.L. (Center for Materials Science and Engineering, Univ. of Texas, Austin (USA))

    1991-01-20

    Tungsten and tungsten-based heavy alloys are well known for their superior mechanical properties at elevated temperatures. However, unalloyed tungsten is difficult to consolidate owing to its very high melting temperature (3683 K). The additions of small amounts of low-melting elements such as iron, nickel, cobalt and copper, facilitate the powder processing of dense heavy alloys at moderate temperatures. Energetic high-current pulses have been used recently for powder consolidation. In this paper, the use of a homopolar generator as a power source to consolidate selected tungsten and tungsten-based alloys is examined. Various materials were consolidated including unalloyed tungsten, W-Nb, W-Ni, and tungsten heavy alloy with boron carbide. The effect of process parameters such as pressure and specific energy input on the consolidation of different alloy systems is described in terms of microstructure and property relationships. (orig.).

  18. Development of quantitative atomic modeling for tungsten transport study Using LHD plasma with tungsten pellet injection

    International Nuclear Information System (INIS)

    Quantitative tungsten study with reliable atomic modeling is important for successful achievement of ITER and fusion reactors. We have developed tungsten atomic modeling for understanding the tungsten behavior in fusion plasmas. The modeling is applied to the analysis of tungsten spectra observed from currentless plasmas of the Large Helical Device (LHD) with tungsten pellet injection. We found that extreme ultraviolet (EUV) lines of W24+ to W33+ ions are very sensitive to electron temperature (Te) and useful to examine the tungsten behavior in edge plasmas. Based on the first quantitative analysis of measured spatial profile of W44+ ion, the tungsten concentration is determined to be n(W44+)/ne= 1.4x10-4 and the total radiation loss is estimated as ∼4 MW, of which the value is roughly half the total NBI power. (author)

  19. The crystallisation of the aluminium bronze with additions of Si, Cr, Mo and/or W

    Directory of Open Access Journals (Sweden)

    B.P. Pisarek

    2007-08-01

    Full Text Available Purpose: The aim of this paper is description of the process of the crystallization of new aluminium bronzes with the complex silicides of the iron.Design/methodology/approach: Additions Cr, W, Mo and Si were introduced to create in the microstructure of the aluminium bronze of the complex silicides of the iron about high mechanical and physical proprieties to the bronze BA1044. The process of formation the microstructure of the bronze with use of the method of the thermal and derivative analysis (TDA was analysed. The examinations under the microscope and X-ray microanalysis of the surface distribution of elements were conducted.Findings: From carried research results, that in the aluminium bronze BA1044 after addition Si, Cr, Mo and/or W the phase κFe, κNi crystallize as the complex silicides of the iron. Elements such as: Fe and Si dissolve first of all in silicides in the smaller stage in the matrix of the bronze, Mn and Ni they dissolve in matrix and silicides, Cr dissolves in the larger stage in silicides than in the matrix, W and Mo dissolve in silicides however they crystallize as nanocrystals in the metal matrix and create with her composite.Research limitations/implications: Results of investigations of aluminium bronze BA1044 and alloys after adding to him about 1% Si were introduced in the article and suitably: 1.22 % Cr; 0.82 % Mo; 0.020 % W; 0.60 % Cr, 0.17 % Mo and 0.017 % W.Originality/value: The original results of the investigations of the crystallization of the new bronzes (innovative materials and casting technologies for which the process of arising microstructure the method TDA was not analysed so far were introduced in the article. The article possesses cognitive values not only essential for researcher but and practician-melters.

  20. Tribological properties of sputtered tungsten and tungsten nitride thin films

    Institute of Scientific and Technical Information of China (English)

    Wong; K.M.; ShenY.G.; Wong; P.L.

    2001-01-01

    The surface roughness, hardness and tribological properties of tungsten (W) and tung-sten nitride (WNx) thin films prepared by dc magnetron sputtering and reactive magnetron sputter-ing in Ar-N2 gas mixtures have been studied using atomic force microscopy (AFM), nanoindenta-tion measurements and ball-on-disc wear testing. A pronounced surface roughness was observedonly for films under compressive strains. The surface was flat under tension but rough under com-pression. Similar hardness with value about 20 GPa were observed in the W and WNx (x=0.3)films. This is thought to be due to the fact the grains are restricted to a very small size in the coat-ings. The higher coefficients of friction (0.4 for W and 0.9 for WN0.3) suggest that WN0.3 is not theoptimum phase. Finally, discussions are made with tribological test results.

  1. Novel properties of Tungsten ditelluride

    Science.gov (United States)

    Liu, Huimei; National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Cent Collaboration

    Tungsten ditelluride has attracted intense research interest due to the recent discovery of its large unsaturated magnetoresistance up to 60 Tesla. By using density functional theory calculations, we qualitatively reproduced the observed spin texture. Since the spin texture would forbid back scatterings that are directly involved in the resistivity, we suggest that the SOC and the related spin and orbital angular momentum textures may play an important role in the anomalously large magnetoresistance of WTe2. Motivated by the presence of a small, sensitive Fermi surface of 5d electronic orbitals, we also boost the electronic properties by applying a high pressure, and introduce superconductivity successfully.

  2. Electrolytic preparation of vanadium(5) oxide from oxovanadium(4) sulfate solution in the presence of sodium ions

    International Nuclear Information System (INIS)

    Influence of anodic current density, pH value and reagents concentration on the character of anodic processes, current efficiency and properties of deposits during electrolytic deposition of vanadium(5) oxide from aqueous solutions of oxovanadium(4) sulfate in the presence of sodium ions was studied. It was ascertained that in the presence of sodium ions some deposits are formed on the anode, which differ qualitatively from the ones prepared from solutions without additions. According to data of X-ray phase analysis the sediments after annealing at 500 deg C for 5-7 h were sodium-vanadium bronze of NaxV2O5 composition, featuring elevated electrochemical activity

  3. Investigating Early/Middle Bronze Age copper and bronze axes by micro X-ray fluorescence spectrometry and neutron imaging techniques

    Science.gov (United States)

    Figueiredo, Elin; Pereira, Marco A. Stanojev; Lopes, Filipa; Marques, José G.; Santos, Joana P.; Araújo, M. Fátima; Silva, Rui J. C.; Senna-Martinez, João C.

    2016-08-01

    Micro X-ray fluorescence (micro-XRF) analysis and neutron imaging techniques, namely 2D radiography and 3D tomography, have been applied for the study of four metal axes from the Early/Middle Bronze Age in Western Iberia, a period characterized by a metallurgical change in the use of copper to bronze. Micro-XRF analysis has shown that one of the axes was produced in copper with some arsenic while the other three were produced in a copper-tin alloy (bronze) with variable tin contents and some arsenic and lead. Neutron radiography and tomography were applied to study internal heterogeneities of the axes in a non-invasive way since the specificities of neutron interaction with matter allow a suitable penetration of these relatively thick copper-based objects when compared to the use of a conventional X-ray radiography. Neutron imaging allowed the visualization of internal fissures and pores and the evaluation of their distribution, size and shape. Relevant information for the reconstruction of ancient manufacturing techniques was gathered, revealing that one ax was produced with the mold in an angle of ≈ 25°, probably to facilitate gas escape during metal pouring. Also, information regarding physical weaknesses of the axes was collected, providing relevant data for their conservation. The combination of these non-destructive techniques allowed the evaluation of the metal composition and the internal structure of the axes. Micro-XRF allowed the distinction among copper and bronze axes, and provided data about the composition of early bronzes for which data is scarce. The neutron imaging study allowed for the first time the visualization of internal heterogeneities in early bronze axes, namely pores and large voids, providing relevant information for the reconstruction of ancient manufacturing techniques and raising pertinent information regarding physical weaknesses of these types of objects.

  4. Characterisation of Late Bronze Age large size shield nails by EDXRF, micro-EDXRF and X-ray digital radiography

    Energy Technology Data Exchange (ETDEWEB)

    Figueiredo, E., E-mail: elin@itn.pt [Instituto Tecnologico e Nuclear, Estrada Nacional 10, 2686-953 Sacavem (Portugal); CENIMAT/I3N, Departamento de Ciencia dos Materiais, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Monte de Caparica (Portugal); Departamento de Conservacao e Restauro, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Monte de Caparica (Portugal); Araujo, M.F. [Instituto Tecnologico e Nuclear, Estrada Nacional 10, 2686-953 Sacavem (Portugal); Silva, R.J.C. [CENIMAT/I3N, Departamento de Ciencia dos Materiais, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Monte de Caparica (Portugal); Senna-Martinez, J.C. [Centro de Arqueologia (Uniarq), Faculdade de Letras, Universidade de Lisboa, 1600-214 Lisboa (Portugal); Ines Vaz, J.L. [Departamento de Letras, Universidade Catolica, Estrada da Circunvalacao, 3504-505 Viseu (Portugal)

    2011-09-15

    In the present study six exceptional large size metallic nails, a dagger and a sickle from the Late Bronze Age archaeological site of Figueiredo das Donas (Central Portugal) have been analysed by EDXRF, micro-EDXRF and X-ray digital radiography for the study of material composition and technology of fabrication. The combination of these analytical and examination techniques showed that all artefacts are made of bronze with As, Sb and Pb impurities, and that the nails were most likely manufactured using the casting-on technique. These results reinforce the use of binary bronze by Late Bronze Age in the region, and the incorporation of new fabrication technologies that resulted from ancient spheres of interaction. - Highlights: > EDXRF, micro-EDXRF and X-ray digital radiography in cultural heritage studies. > Archaeometallurgical study of a Late Bronze Age artefact collection from Portugal. > Practise of a specific and traditional bronze metallurgy. > Appearance of technological innovations as the casting-on technique.

  5. Platinum-tungsten electrodes for the alkali metal thermoelectric converter

    International Nuclear Information System (INIS)

    Co-sputtered platinum-tungsten AMTEC electrodes have shown high power densities (--0.5 X/cm/sup 2/) after operation at --1180 K for periods up to 93 hours. After a brief period (--20 hours) of power density decline from initial values as high as 0.7 W/cm/sup 2/, power is constant or increases slowly with time. Electrodes before and after AMTEC operation have low porosity, suggesting that mass transport does not depend solely on gas-phase diffusion. Model system studies have included synthesis of a platinum-sodium compound, Pt/sub x/Na; determination of the temperature dependence of the open circuit potential of a test cell Na/sub iota//sodium beta''-alumina/Pt/sub x/Na, Pt; and study of the properties of pure platinum electrodes. These studies show that Pt/sub x/Na is thermodynamically stable up to high temperatures (>900K), but is not generally stable at the low sodium activities calculated for AMTEC electrodes under typical operating conditions. Surface diffusion enhanced transport is suggested by these results

  6. Development of tungsten fibre-reinforced tungsten composites towards their use in DEMO—potassium doped tungsten wire

    Science.gov (United States)

    Riesch, J.; Han, Y.; Almanstötter, J.; Coenen, J. W.; Höschen, T.; Jasper, B.; Zhao, P.; Linsmeier, Ch; Neu, R.

    2016-02-01

    For the next step fusion reactor the use of tungsten is inevitable to suppress erosion and allow operation at elevated temperature and high heat loads. Tungsten fibre-reinforced composites overcome the intrinsic brittleness of tungsten and its susceptibility to operation embrittlement and thus allow its use as a structural as well as an armour material. That this concept works in principle has been shown in recent years. In this contribution we present a development approach towards its use in a future fusion reactor. A multilayer approach is needed addressing all composite constituents and manufacturing steps. A huge potential lies in the optimization of the tungsten wire used as fibre. We discuss this aspect and present studies on potassium doped tungsten wire in detail. This wire, utilized in the illumination industry, could be a replacement for the so far used pure tungsten wire due to its superior high temperature properties. In tensile tests the wire showed high strength and ductility up to an annealing temperature of 2200 K. The results show that the use of doped tungsten wire could increase the allowed fabrication temperature and the overall working temperature of the composite itself.

  7. Development of quantitative atomic modeling for tungsten transport study using LHD plasma with tungsten pellet injection

    Science.gov (United States)

    Murakami, I.; Sakaue, H. A.; Suzuki, C.; Kato, D.; Goto, M.; Tamura, N.; Sudo, S.; Morita, S.

    2015-09-01

    Quantitative tungsten study with reliable atomic modeling is important for successful achievement of ITER and fusion reactors. We have developed tungsten atomic modeling for understanding the tungsten behavior in fusion plasmas. The modeling is applied to the analysis of tungsten spectra observed from plasmas of the large helical device (LHD) with tungsten pellet injection. We found that extreme ultraviolet (EUV) emission of W24+ to W33+ ions at 1.5-3.5 nm are sensitive to electron temperature and useful to examine the tungsten behavior in edge plasmas. We can reproduce measured EUV spectra at 1.5-3.5 nm by calculated spectra with the tungsten atomic model and obtain charge state distributions of tungsten ions in LHD plasmas at different temperatures around 1 keV. Our model is applied to calculate the unresolved transition array (UTA) seen at 4.5-7 nm tungsten spectra. We analyze the effect of configuration interaction on population kinetics related to the UTA structure in detail and find the importance of two-electron-one-photon transitions between 4p54dn+1- 4p64dn-14f. Radiation power rate of tungsten due to line emissions is also estimated with the model and is consistent with other models within factor 2.

  8. Selective tungsten deposition: Temperature-programmed studies on silicon, silicon dioxide, and tungsten surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Hindman, G.T.

    1989-01-01

    Selective tungsten chemical vapor deposition (CVD) is a technique which has shown considerable promise for the semiconductor manufacturing industry due to tungsten's physical properties and its ability to be deposited in a spatially selective manner. Routine employment of selective tungsten deposition has been impeded by a lack of knowledge about processes by which selectivity is lost. In order to better understand the cause of selectivity loss and the chemistry of selective tungsten CVD, the interactions of WF{sub 6} on SiO{sub 2}, Si, and W surfaces were studied in ultra high vacuum (UHV) using Temperature Programmed Reaction Spectroscopy. These experiments revealed that WF{sub 6} is capable of reacting with a native oxide surface even at low temperatures. Tungsten oxyfluorides or silicon oxyfluorides desorption signals were not observed from either thick thermal or thin native oxide surfaces. On Si(100) multiple overlapping WF{sub 6} desorption peaks were observed. These chemisorption peaks shifted to higher temperatures with increasing exposure, and are believed to be due to the decomposition of a W-Si-F corrosion layer. Hydrogen did not adsorb on silicon surfaces containing appreciable amounts of tungsten. Tungsten and silicon rapidly interdiffused in tungsten films grown in situ by silicon reduction. Silicon on or in these in situ W films was more reactive than clean, tungsten-free silicon. Experiments on polycrystalline tungsten revealed that WF{sub 6} adsorption is partially irreversible.

  9. Photocatalysis and Photoelectrochemical Properties of Tungsten Trioxide Nanostructured Films

    Directory of Open Access Journals (Sweden)

    Chin Wei Lai

    2014-01-01

    Full Text Available Tungsten trioxide (WO3 possesses a small band gap energy of 2.4–2.8 eV and is responsive to both ultraviolet and visible light irradiation including strong absorption of the solar spectrum and stable physicochemical properties. Thus, controlled growth of one-dimensional (1D WO3 nanotubular structures with desired length, diameter, and wall thickness has gained significant interest. In the present study, 1D WO3 nanotubes were successfully synthesized via electrochemical anodization of tungsten (W foil in an electrolyte composed of 1 M of sodium sulphate (Na2SO4 and ammonium fluoride (NH4F. The influence of NH4F content on the formation mechanism of anodic WO3 nanotubular structure was investigated in detail. An optimization of fluoride ions played a critical role in controlling the chemical dissolution reaction in the interface of W/WO3. Based on the results obtained, a minimum of 0.7 wt% of NH4F content was required for completing transformation from W foil to WO3 nanotubular structure with an average diameter of 85 nm and length of 250 nm within 15 min of anodization time. In this case, high aspect ratio of WO3 nanotubular structure is preferred because larger active surface area will be provided for better photocatalytic and photoelectrochemical (PEC reactions.

  10. Test Your Sodium Smarts

    Science.gov (United States)

    ... You may be surprised to learn how much sodium is in many foods. Sodium, including sodium chloride ... foods with little or no salt. Test your sodium smarts by answering these 10 questions about which ...

  11. Environmental fate of tungsten from military use

    International Nuclear Information System (INIS)

    This manuscript describes the distribution, fate and transport of tungsten used in training rounds at three small arms ranges at Camp Edwards on the Massachusetts Military Reservation (MMR), USA. Practice with tungsten/nylon rounds began in 2000 subsequent to a 1997 US Environmental Protection Agency ban on training with lead. Training with the tungsten rounds was halted in 2005 because of concerns regarding tungsten's environmental mobility and potential toxicity. This study, therefore, examines how tungsten partitions in the environment when fired on a small arms training range. Soil sampling revealed surface soil concentrations, highest at the berm face, up to 2080 mg/kg. Concentrations decreased rapidly with depth-at least by an order of magnitude by 25 cm. Nonetheless, tungsten concentrations remained above background to at least 150 cm. Pore-water samples from lysimeters installed in berm areas revealed a range of concentrations (< 1-400 mg/L) elevated with respect to background although there was no discernable trend with depth. Groundwater monitoring well samples collected approximately 30 m below ground surface showed tungsten (0.001-0.56 mg/L) attributable to range use

  12. Environmental fate of tungsten from military use

    Energy Technology Data Exchange (ETDEWEB)

    Clausen, Jay L. [Research and Development Center, Cold Regions Research and Engineering Laboratory, 72 Lyme Road, Hanover, New Hampshire, 03755 (United States)], E-mail: Jay.L.Clausen@erdc.usace.army.mil; Korte, Nic [1946 Clover Ct., Grand Junction, Colorado, 81506 (United States)

    2009-04-01

    This manuscript describes the distribution, fate and transport of tungsten used in training rounds at three small arms ranges at Camp Edwards on the Massachusetts Military Reservation (MMR), USA. Practice with tungsten/nylon rounds began in 2000 subsequent to a 1997 US Environmental Protection Agency ban on training with lead. Training with the tungsten rounds was halted in 2005 because of concerns regarding tungsten's environmental mobility and potential toxicity. This study, therefore, examines how tungsten partitions in the environment when fired on a small arms training range. Soil sampling revealed surface soil concentrations, highest at the berm face, up to 2080 mg/kg. Concentrations decreased rapidly with depth-at least by an order of magnitude by 25 cm. Nonetheless, tungsten concentrations remained above background to at least 150 cm. Pore-water samples from lysimeters installed in berm areas revealed a range of concentrations (< 1-400 mg/L) elevated with respect to background although there was no discernable trend with depth. Groundwater monitoring well samples collected approximately 30 m below ground surface showed tungsten (0.001-0.56 mg/L) attributable to range use.

  13. Fabrication and properties of tungsten heavy metal alloys containing 30% to 90% tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Gurwell, W.E.; Nelson, R.G.; Dudder, G.B.; Davis, N.C.

    1984-09-01

    In 1983, Pacific Northwest Laboratory conducted a survey of tungsten heavy metal alloys having lower-than-normal (<90%) tungsten content. The purpose of the work was to develop tougher, more impact-resistant high-density alloys for applications benefitting from improved mechanical properties. Tungsten heavy metal alloys of 30 to 90% tungsten content were fabricated and their mechanical properties measured. Although ultimate strength was essentially independent of tungsten content, lower tungsten-content alloys had lower yield stress, hardness, and density, and decidedly higher elongations and impact energies. Cold work was effective in raising strength and hardness but detrimental to elongation and impact energies. Precipitation hardening and strain aging raised hardness effectively but had less influence on other mechanical properties. 34 figures, 7 tables.

  14. Rapid and direct determination of percentage tungsten in tantalum-10% tungsten alloy by Wavelength Dispersive X-Ray Fluorescence Spectrometry

    International Nuclear Information System (INIS)

    A method for rapid and direct determination of percentage tungsten in tungsten-tantalum alloy by Wavelength Dispersive X-Ray Fluorescence Spectrometry has been developed for the routine determination of tungsten in tantalum-10% tungsten alloy samples. A RSD of < 1% is obtained in the technique. (author)

  15. Combustion of powdery tungsten in pyrotechnic mixtures

    International Nuclear Information System (INIS)

    The basic regularities of tungsten burning (powder 2-5 μm) with oxidizers most typical for pyrotechnics: nitrates, lead and barium peroxides (powder, 2-8 μm) and potassium perchlorate (powder, 2-8 μm) are studied. Dependences of burning rate as a function of pressure and ratio of components are established. It is supposed that tungsten burning in mixtures with the mentioned nitrates is a complex and multistage process the rate of which is determined by tungsten dissolution in nitrate melts. Analysis of burning products using available methods is complex

  16. Tungsten coatings and free standing parts

    Czech Academy of Sciences Publication Activity Database

    Brožek, Vlastimil; Ctibor, Pavel; Matějíček, Jiří; Mušálek, Radek; Weiss, Z.

    Ostrava : Tanger spol. s r.o, 2013, 1445-1-14445-6. ISBN 978-80-87294-39-0. [METAL 2013 - International Conference on Metallurgy and Materials /22./. Brno (CZ), 15.05.2013-17.05.2013] R&D Projects: GA ČR(CZ) GAP108/12/1872 Institutional support: RVO:61389021 Keywords : tungsten coatings * tungsten filters * plasma spray ing * shrouding * tungsten plasma spray ing * protection against oxidation Subject RIV: CA - Inorganic Chemistry http://www.metal2013.com/files/proceedings/12/reports/1445.pdf

  17. Tungsten Ditelluride: a layered semimetal

    Science.gov (United States)

    Lee, Chia-Hui; Silva, Eduardo Cruz; Calderin, Lazaro; Nguyen, Minh An T.; Hollander, Matthew J.; Bersch, Brian; Mallouk, Thomas E.; Robinson, Joshua A.

    2015-06-01

    Tungsten ditelluride (WTe2) is a transition metal dichalcogenide (TMD) with physical and electronic properties that make it attractive for a variety of electronic applications. Although WTe2 has been studied for decades, its structure and electronic properties have only recently been correctly described. We experimentally and theoretically investigate the structure, dynamics and electronic properties of WTe2, and verify that WTe2 has its minimum energy configuration in a distorted 1T structure (Td structure), which results in metallic-like transport. Our findings unambiguously confirm the metallic nature of WTe2, introduce new information about the Raman modes of Td-WTe2, and demonstrate that Td-WTe2 is readily oxidized via environmental exposure. Finally, these findings confirm that, in its thermodynamically favored Td form, the utilization of WTe2 in electronic device architectures such as field effect transistors may need to be reevaluated.

  18. Characterization of nanometer tungsten powders

    Institute of Scientific and Technical Information of China (English)

    LI Huiqian; LIN Tao; SHAO Huiping; WU Chengyi; GUO Zhimeng; LUO Ji

    2008-01-01

    Three types of tungsten powders were prepared by hydrogen reduction of three precursor powders at low temperature,which were used as samples,and were then characterized by Brunauer-Emmer-Teller (BET) method,scanning electron microscopy (SEM),transmission electronic microscopy (TEM),small angle X-ray scattering (SAXS),and field-emission scanning electron microscopy (FESEM) respectively.The results showed that although BET and SEM could not characterize the particle size of nanometer powders,they were important means of assistance to exclude non-nanometer powders.TEM and FESEM could directly measure the particle size of nanometer powders,but this needs a lot of time,to count the average particle size and particle size distribution.SAXS could not describe the state of agglomeration.By the combination of FESEM and SAXS,the particle size,particle size distribution,and particle shape of nanorneter powders could be preciscly characterized.

  19. Feasibility Study of a Tungsten Wire Reinforced Tungsten Matrix Composite with ZrOx Interfacial Coatings

    OpenAIRE

    Du, J.; Höschen, T.; Rasinski, M.; Wurster, S; Grosinger, W.; You, J-H.

    2007-01-01

    Abstract Brittleness problem imposes a severe restriction on the potential application of tungsten as high-temperature structural material. In this paper, a novel toughening method for tungsten is proposed based on reinforcement by tungsten wires. The underlying toughening mechanism is analogous to that of fiber-reinforced ceramic matrix composites. Strain energy is dissipated by debonding and frictional sliding at engineered fiber/matrix interfaces. To achieve maximum composite to...

  20. Visible light photoinactivation of bacteria by tungsten oxide nanostructures formed on a tungsten foil

    International Nuclear Information System (INIS)

    Highlights: • Synthesis of tungsten oxide nano/micro-structures on W foils using KOH as a catalyst. • Strong antibacterial activity of tungsten oxide nanorods under visible light irradiation. • Decrease in photoinactivation of bacteria on tungsten oxide nano/micro-rods doped by potassium. - Abstract: Antibacterial activity of tungsten oxide nanorods/microrods were studied against Escherichia coli bacteria under visible light irradiation and in dark. A two-step annealing process at temperatures up to 390 °C and 400–800 °C was applied to synthesize the tungsten oxide nanorods/microrods on tungsten foils using KOH as a catalyst. Annealing the foils at 400 °C in the presence of catalyst resulted in formation of tungsten oxide nanorods (with diameters of 50–90 nm and crystalline phase of WO3) on surface of tungsten foils. By increasing the annealing temperature up to 800 °C, tungsten oxide microrods with K2W6O19 crystalline phase were formed on the foils. The WO3 nanorods showed a strong antibacterial property under visible light irradiation, corresponding to >92% bacterial inactivation within 24 h irradiation at room temperature, while the K2W6O19 microrods formed at 800 °C could inactivate only ∼45% of the bacteria at the same conditions

  1. Visible light photoinactivation of bacteria by tungsten oxide nanostructures formed on a tungsten foil

    Energy Technology Data Exchange (ETDEWEB)

    Ghasempour, Fariba [Plasma Physics Research Centre, Science and Research Branch, Islamic Azad University, P.O. Box 147789-3855, Tehran (Iran, Islamic Republic of); Azimirad, Rouhollah [Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Amini, Abbas [School of Computing, Engineering and Mathematics, University of Western Sydney, Kingswood, NSW 2751 (Australia); Akhavan, Omid, E-mail: oakhavan@sharif.edu [Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 14588-89694, Tehran (Iran, Islamic Republic of)

    2015-05-30

    Highlights: • Synthesis of tungsten oxide nano/micro-structures on W foils using KOH as a catalyst. • Strong antibacterial activity of tungsten oxide nanorods under visible light irradiation. • Decrease in photoinactivation of bacteria on tungsten oxide nano/micro-rods doped by potassium. - Abstract: Antibacterial activity of tungsten oxide nanorods/microrods were studied against Escherichia coli bacteria under visible light irradiation and in dark. A two-step annealing process at temperatures up to 390 °C and 400–800 °C was applied to synthesize the tungsten oxide nanorods/microrods on tungsten foils using KOH as a catalyst. Annealing the foils at 400 °C in the presence of catalyst resulted in formation of tungsten oxide nanorods (with diameters of 50–90 nm and crystalline phase of WO{sub 3}) on surface of tungsten foils. By increasing the annealing temperature up to 800 °C, tungsten oxide microrods with K{sub 2}W{sub 6}O{sub 19} crystalline phase were formed on the foils. The WO{sub 3} nanorods showed a strong antibacterial property under visible light irradiation, corresponding to >92% bacterial inactivation within 24 h irradiation at room temperature, while the K{sub 2}W{sub 6}O{sub 19} microrods formed at 800 °C could inactivate only ∼45% of the bacteria at the same conditions.

  2. Tungsten carbide production from ore concentrates by molten salt-natural gas sparging treatment

    International Nuclear Information System (INIS)

    The U.S. Bureau of Mines conducted a bench-scale study to delineate the important parameters in a three-step process to produce commercial-quality tungsten carbide (WC) directly from tungsten minerals. In the process, tungsten concentrates of wolframite or wolframite and scheelite are decomposed at 1,0500C in a molten mixture of NcCl and Na2SiO3 that forms two immiscible phases. Tungsten, as sodium tungstate, reports to the halide phase and is separated from the gangue constituents, which report to the silicate phase. After decanting to separate the two phases, natural gas is sparged into the molten halide phase a 1,0700C. Submicrometer crystals of WC are initially produced. These crystals grow into thin triangular-shaped plates up to 100 μm on a side or into popcorn-shaped conglomerates. Sparged WC was examined for its suitability for use in sintered carbide products. In physical evaluations, sparged WC ground to an average particle size of 1.52 μm and compacted with 10 pct Co binder into standard 6-by 22-mm test bars had a density of 14.35 and a Rockwell A hardness of 89.6. This compared favorably with 14.39 and 89.7 respectively, for test bars made from a standard commercial 1.52-μm WC powder. Test bars made from Bureau of Mines WC had no ''C'' porosity or eta phase

  3. Exploring the bronzing effect at the surface of ink layers

    Science.gov (United States)

    Hébert, Mathieu; Mallet, Maxime; Deboos, Alexis; Chavel, Pierre; Kuang, Deng-Feng; Hugonin, Jean-Paul; Besbes, Mondher; Cazier, Anthony

    2015-03-01

    We investigate the optical phenomenon responsible for the colored shine that sometimes appears at the surface of ink layers in the specular direction, often called bronzing or gloss differential. It seems to come from the wavelength-dependent refractive index of the ink, which induces a wavelength-dependent reflectance of the ink-air interface. Our experiments on cyan and magenta inkjet inks confirm this theory. Complex refractive indices can be obtained from measurements of the spectral reflectance and transmittance of a transparency film coated with the ink. We propose a correction of the classical Clapper-Yule model in order to include the colored gloss in the prediction of the spectral reflectance of an inked paper. We also explored effects of scattering by the micrometric or nanometric roughness of the ink surface. The micrometric roughness, easy to model with a geometrical optics model, can predict the spreading of the colored gloss over a large cone. Electromagnetic models accounting for the effect of the nanometric roughness of the surface also predict the attenuation of short wavelengths observed under collimated illumination.

  4. Flux pinning in bronze-processed Nb3Sn wires

    International Nuclear Information System (INIS)

    The scaling law derived by Kramer for magnetic flux pinning in high magnetic fields was examined for its applicability to the magnetic field dependence of critical-current densities in the bronze processed monofilamentary Nb3Sn wires. From this it was concluded that: (1) its prediction for the form of the dependence of critical current on magnetic field and grain size [/J vector /sub c/ x H vector/ approx. h/sup 1/2/(1-h)2(1-a0√rho)-2] was found to be very good in most cases including wires with very small Nb3Sn grains (approx. 400 A). It was found very useful in comparison of J/sub c/ for different wires and in extrapolating to obtain H/sub c2/ for these wires. (2) However, it could not account consistently for the anisotropy in critical current of a tape which was measured with H applied perpendicular and parallel to the tape face. (3) The values of kappa1 which were determined with the scaling law were too small by a factor of 2 to 3, and the trend in the variation with heat-treating time was opposite to that which is reasonably to be expected. That the behavior of kappa1 is thus seriously in contradiction with the expected behavior for Nb3Sn suggests basic faults in the derivation of the scaling equation for critical currents at high magnetic fields

  5. Dating simple flakes: Early Bronze Age flake production technology on the Middle Euphrates Steppe, Syria

    Directory of Open Access Journals (Sweden)

    Yoshihiro Nishiaki

    2014-03-01

    Full Text Available Aceramic flint scatters, comprising very crude cores or flakes and no formalised tools, are frequently found on the Middle Euphrates steppe of northern Syria. Previous studies suggest that many of them are residues of short-term activities by the nomads or shepherds of the Early Bronze Age. In order to verify this interpretation, a more precise chronological framework needs to be established for the Early Bronze Age lithic industry. This paper analyses stratified flake assemblages of the Early Bronze Age at Tell Ghanem al-Ali, a securely radiocarbon-dated settlement on the Middle Euphrates, and examines which occupation level yields assemblages most similar to those of the steppe. Results demonstrate that the lithic industry of this period underwent significant diachronic changes in terms of core reduction technology. Based on the chronological framework developed at Tell Ghanem al-Ali, the steppe assemblages in question can be assigned to different phases of the Early Bronze Age. This finding will help identify processes at the beginning of the extensive exploitation of the steppe, which is regarded as one of the most important socioeconomic changes that occurred among Early Bronze Age communities of the Middle Euphrates.

  6. Corrosion of Bronzes by Extended Wetting with Single versus Mixed Acidic Pollutants

    Directory of Open Access Journals (Sweden)

    Liliana Gianni

    2014-04-01

    Full Text Available The corrosion of bronzes was examined in the context of single-acid versus mixed-acid (as in urban acid rain solutions. Two bi-component bronzes (copper with either 3% Sn or 7% Sn that closely represent those of historic artifacts were immersed for five weeks in conditions designed to replicate those experienced by statues and ornaments in cities where rainfall and humidity constantly produce an electrolyte layer on the surfaces of bronzes. Ions, acids, and particles of pollutants can dissolve in this layer, resulting in a variety of harsh corrosion processes. The kinetics of corrosion and the properties of the resulting patinas were monitored weekly by electrochemical impedance spectroscopy and open-circuit potential measurements. The sizes and appearances of the corrosion products were monitored and used to estimate the progress of the corrosion, whose crystalline structures were visualized using scanning electron microscopy with energy dispersive spectroscopy, identified by X-ray diffraction, and characterized by spectrocolorimetry. The electrochemical measurements demonstrated that greater damage (in terms of color change and corrosion product formation did not correspond to deficiencies in protection. The mixed-acid solution did not corrode the bronzes, as would be expected from the additive effects of the single acids. The postulated mechanisms of metal dissolution appear to be specific to a particular bronze alloy, with the tin component playing an important role.

  7. Improvement in tungsten sponge production technology

    International Nuclear Information System (INIS)

    With the aim of searching methods of direct reduction of tungsten oxide concentrates or thermodynamical study of the W-O-C system is accomplished. It is established that the following thermodynamic equilibria are of interest for practice: equilibria of WO2 formation reaction, equilibria of tungsten reduction with carbon, tungsten carbide and carbon monoxide. A two-stage process of manufacturing tungsten-bearing metallized concentrate is developed on the basis of study results. The first stage of reduction runs at 973-1223 K for 4-9 h. The second stage is carried out at 1273-1723 K during 2-6 h with subsequent cooling in a gas environment down to 273-303 K. The density of produced metallized briquets equals 3.2-3.67 g/cm3

  8. Modeling of hydrogen desorption from tungsten surface

    International Nuclear Information System (INIS)

    Hydrogen retention in metallic plasma-facing components is among key-issues for future fusion devices. For tungsten, which has been chosen as divertor material in ITER, hydrogen desorption parameters experimentally measured for fusion-related conditions show large discrepancies. In this paper, we therefore investigate hydrogen recombination and desorption on tungsten surfaces using molecular dynamics simulations and accelerated molecular dynamics simulations to analyze adsorption states, diffusion, hydrogen recombination into molecules, and clustering of hydrogen on tungsten surfaces. The quality of tungsten hydrogen interatomic potential is discussed in the light of MD simulations results, showing that three body interactions in current interatomic potential do not allow to reproduce hydrogen molecular recombination and desorption. Effects of surface hydrogen clustering on hydrogen desorption are analyzed by introducing a kinetic model describing the competition between surface diffusion, clustering and recombination. Different desorption regimes are identified and reproduce some aspects of desorption regimes experimentally observed

  9. Modeling of hydrogen desorption from tungsten surface

    Energy Technology Data Exchange (ETDEWEB)

    Guterl, J., E-mail: jguterl@ucsd.edu [University of California, San Diego, La Jolla, CA 92093 (United States); Smirnov, R.D. [University of California, San Diego, La Jolla, CA 92093 (United States); Krasheninnikov, S.I. [University of California, San Diego, La Jolla, CA 92093 (United States); Nuclear Research National University MEPhI, Moscow 115409 (Russian Federation); Uberuaga, B.; Voter, A.F.; Perez, D. [Los Alamos National Laboratory, Los Alamos, NM 8754 (United States)

    2015-08-15

    Hydrogen retention in metallic plasma-facing components is among key-issues for future fusion devices. For tungsten, which has been chosen as divertor material in ITER, hydrogen desorption parameters experimentally measured for fusion-related conditions show large discrepancies. In this paper, we therefore investigate hydrogen recombination and desorption on tungsten surfaces using molecular dynamics simulations and accelerated molecular dynamics simulations to analyze adsorption states, diffusion, hydrogen recombination into molecules, and clustering of hydrogen on tungsten surfaces. The quality of tungsten hydrogen interatomic potential is discussed in the light of MD simulations results, showing that three body interactions in current interatomic potential do not allow to reproduce hydrogen molecular recombination and desorption. Effects of surface hydrogen clustering on hydrogen desorption are analyzed by introducing a kinetic model describing the competition between surface diffusion, clustering and recombination. Different desorption regimes are identified and reproduce some aspects of desorption regimes experimentally observed.

  10. Nanostructured Tungsten Materials by Chemical Methods

    OpenAIRE

    Wahlberg, Sverker

    2011-01-01

    Tungsten based-materials are used in many different technical fields, particularly in applications requiring good temperature and/or erosion resistance. Nanostructuring of tungsten alloys and composites has the potential to dramatically improve the materials’ properties, enhancing the performance in present applications or enabling totally new possibilities. Nanostructured WC-Co composites have been the focus of researchers and industries for over two decades. New methods for powder fabricati...

  11. Volume-dependent potential approach for tungsten

    International Nuclear Information System (INIS)

    A scheme to produce density-of-states-(DOS)-dependent potentials for d-metals on the basis of the local density approximation calculations is suggested. As an example this scheme is applied to construct a DOS-dependent potential for tungsten. The second moment of the tungsten DOS is calculated. The authors show that the obtained potentials give a good agreement of cohesive properties with the experimental data

  12. Preparation of tungsten filters and membranes

    Czech Academy of Sciences Publication Activity Database

    Brožek, Vlastimil; Matějíček, Jiří; Neufuss, Karel

    Lillehammer - Norway : Ed.Bredesen & Raeder, SINTEF, Norway, 2006, s. 637-640. ISBN 82-14-04026-5. [International Conference on Inorganic Membranes 9ICIM /9th./. Lillehammer, Norway (NO), 25.06.2006-29.06.2006] R&D Projects: GA ČR(CZ) GA104/05/0540 Institutional research plan: CEZ:AV0Z20430508 Keywords : tungsten * tungsten carbide * metallic membranes * metallic filters Subject RIV: JK - Corrosion ; Surface Treatment of Materials

  13. 青铜乐器自名研究%A Study of the Names Inscribed on Bronze Musical Instruments

    Institute of Scientific and Technical Information of China (English)

    陈双新

    2001-01-01

    Based on his studies of the bronze musical instruments, the author analyses the inscriptions referring the self-named modifiers and tries to give them new explanations. The study is important to understand the function and values of the bronze musical instruments.

  14. Tungsten foil laminate for structural divertor applications – Analyses and characterisation of tungsten foil

    International Nuclear Information System (INIS)

    It has been attempted for several years to synthesise a tungsten material with a low brittle-to-ductile transition temperature and a high fracture toughness that can be used for structural parts. It was shown in our previous work that tungsten foil is ductile at room temperature and that this ductility can be transformed to bulk by synthesising a tungsten laminate. In this work we want to focus on tungsten foil and assess the microstructure as well as the mechanical properties of the foil. The assessment of the microstructure of 0.1 mm tungsten foil will be performed using electron microscopy. It will be shown that the grains of the tungsten foil have a dimension of 0.5 μm × 3 μm × 15 μm and a clear texture in (1 0 0) 〈0 1 1〉. This texture becomes even more pronounced by annealing. Three-point-bending tests with tungsten foil, as-received, will define the barriers: ductile at room temperature and brittle in liquid nitrogen (−196 °C). This shows that the ductility is a thermally activated process. Recrystallised tungsten foil (annealed for 1 h/2700 °C) shows ductile material behaviour at 200 °C. The paper closes with a discussion on the reasons of the ductility of 0.1 mm tungsten foil. These might be the ultra fine grained (UFG) microstructure or, in other words, a nano microstructure (see tungsten foil as-received), the high amount of mobile edge dislocations, and/or the foil effect, which means that dislocations can move to the surface and are annihilated (see tungsten foil recrystallised).

  15. DEGRADATION WORKS OF MONUMENTAL ART CAST BRONZE UNDER THE INFLUENCE OF ENVIRONMENTAL FACTORS

    Directory of Open Access Journals (Sweden)

    Delia NICA-BADEA

    2012-11-01

    Full Text Available Intensive pollution, combined with the lack of conservation of monuments exposed to these environments make the main cause of deterioration of cultural objects to atmospheric corrosion metal. This paper proposes a study of the main factors leading to degradation Bronze alloy, cast bronze monuments exposed to open atmosphere: corrosive environmental factors, stability and products of corrosion of bronze. In general, all corrosion products present on a metal surface are indicated as 'skate', can be composed of single-layer or multilayer products. The paper also includes a case study on the influence of environmental factors on degradation Matthias monument statue in Cluj-Napoca, Romania. Visual inspection of the monument informs us that have white spots, gray, reddish not consistent with the base color green patina, surfaces showing depigmentation, the rain washed areas, crystallization, deposition of air-borne particles.

  16. Preliminary study on corrosion layers of unearthed bronzes relics of Xizhou dynasty, China

    International Nuclear Information System (INIS)

    Engineering barrier for HLW repository is composed of vitrified waste, canister and buffer/backfill material. Assessment of the applicability of metal as candidate materials of canister for HLW has been conducted in some countries.. Many bronze relics in Xizhou Dynasty, China, dated from more than 3000 years ago, have been preserved perfectly. The study on the corrosion of the bronze relics would contribute to the material selection and design of canister for HLW. The corrosion products of ancient bronzes consist of copper carbonate hydrate, lead carbonate, copper oxides etc. The corrosion mechanism of the substrate were mainly characterized by electrochemical corrosion, whereas the corrosion mechanism of surface layers was characterized by direct chemical corrosion and electrochemical corrosion. (author)

  17. The huastec region: a second locus for the production of bronze alloys in ancient mesoamerica.

    Science.gov (United States)

    Hosler, D; Stresser-Pean, G

    1992-08-28

    Chemical analyses of 51 metal artifacts, one ingot, and two pieces of intermediate processed material from two Late Post Classic archeological sites in the Huastec area of Eastern Mesoamerica point to a second production locus for copper-arsenic-tin alloys, copper-arsenic-tin artifacts, and probably copper-tin and copper-arsenic bronze artifacts. Earlier evidence had indicated that these bronze alloys were produced exclusively in West Mexico. West Mexico was the region where metallurgy first developed in Mesoamerica, although major elements of that technology had been introduced from the metallurgies of Central and South America. The bronze working component of Huastec metallurgy was transmitted from the metalworking regions of West Mexico, most likely through market systems that distributed Aztec goods. PMID:17742754

  18. Production of multifilamentary Nb3Sn composites incorporating a high tin bronze

    International Nuclear Information System (INIS)

    The economics and processing methods have been examined for the fabrication of multifilamentary Nb3Sn using a high tin bronze reactive matrix. Four conductor configurations utilizing the high tin bronze were compared with a conventional Cu-13 wt % Sn bronze. The most promising of these designs is potentially 40% lower in cost per ampere meter than the conventional composite. Large hydrostatic extrusion facilities, which are required for the high tin processing, are not presently available in this country but can be made by conversion of conventional presses. They exist in Europe. Experiments were conducted to investigate the applicability of hydrostatic extrusion, and billet components were successfully prepared using the hydrostatic extrusion technique. We have concluded that the economics, availability of facilities and initial fabrication results are favorable for this type of conductor and that the next stage in this program of scale up to extrusion and drawing of 2'' to 3'' diameter composite billets should be undertaken

  19. An algorithm of heat engineering computation of leaching tungsten concentrates by soda solutions in autoclaves

    International Nuclear Information System (INIS)

    Algorithms for heat engineering computation of leaching tungsten concentrates by soda solutions in horizontal rotary autoclaves and in autoclave batteries have been developed, computer programs being prepared on their basis. Having obtained from mathematically processes reference tabular data the following models found their application in the algorithms: a model relating steam pressure over soda-wolframate solution to temperature and sodium wolframate and soda content of the solution; a model of pressure dependence of steam saturation temperature; and a model of temperature dependence of steam enthalpies and steam condensate. Practical application recommendations for the models developed are given in the paper. A schematic flow diagram of computation algorithm for leaching tungsten concentrate with soda solution in the autoclave battery is also illustrated

  20. Practical bronze alloy for Nb3Sn superconductors. Microstructure and cold-workability

    International Nuclear Information System (INIS)

    Copper-Tin (Cu-Sn) bronze alloy is the key material for bronze-processed Nb3Sn superconducting wires. The Osaka Alloying Works in Japan has established a unique melting process for large-scale bronze alloys called the 'Mizuta method'. In this process, the graphite crucible containing hot molten metal is cooled by passing it directly through a water shower. A general mold casting is not needed, so only slight oxidation of the hot molten metal occurs. Since a uni-directional solidification process is used, a very homogeneous tin concentration without severe inverse segregation in the longitudinal direction of the ingots is obtained. In this paper, we investigate the microstructure and mechanical performance details of the practical bronze having Sn concentrations of 14, 15 and 16 mass%. Elongation, 0.2% toughness, Vickers hardness at room temperature, and the limit of continuous cold-drawability as a function of intermediate annealing were studied. Degradation of cold-drawability was excessive, with a rather low annealing temperature of 400degC. We found that numerous fine precipitates appeared at the intra- and inter-alpha grains after low-temperature annealing. The transmission electron microstructure analysis revealed that those precipitates were the delta phase (Cu41Sn11). The delta precipitates may behave as a pinning site of the slip motion for the plastic deformation of bronze alloys. We have to re-recognize that the intermediate annealing temperature is a very important parameter for avoiding wire breakage during the industrial production of bronze-processed Nb3Sn superconductors. (author)

  1. Ancient bronze horse muzzles of the Iberian Peninsula

    Directory of Open Access Journals (Sweden)

    Garcés Estallo, Ignasi

    2011-12-01

    Full Text Available Horse muzzles and Bronze muzzles are unique equestrian tools that have been referred to in scattered accounts throughout history. Nevertheless, the majority of these objects have received short descriptions and an overall study is still missing. The lack of a comprehensive study hinges on the over looked importance of these items and the superficial manner that have characterized their documentation. Both these reasons have limited observations on chronology and archaeological investigation. The recent identification of new unpublished exemplars among the Museums’ collections in Barcelona and Lleida has encouraged the authors of this paper to start a new study dedicated to these objects. Starting from a catalogue inclusive of all muzzles and muzzles currently known in the Iberian Peninsula, an attempt will be made to propose an accurate description, typological classification and, for some of the items, a revision of the decorative scenes that have marked their place in bronze horse muzzle and muzzle chronology. The formal development and the chronological framework here proposed refer to those of the exemplars found in Greece and in Italy. The broadening of the geographical area will allow reconsideration of those social phenomena that have in the past determined the diffusion of elements in horse tack throughout most of the western Peninsula in the Mediterranean.

    Los bozales y las muserolas en bronce para caballo constituyen unos excepcionales complementos ecuestres cuyo conocimiento se encuentra disperso en una extensa bibliografía. De muchos ejemplares apenas se ha publicado una breve descripción y nunca hasta el presente han sido objeto de un estudio monográfico, quizás por el desaliento que produce el desconocimiento de su procedencia en unos casos, o la superficial noticia del contexto de aparición en la mayoría de ellos, hecho que ha limitado las consideraciones cronológicas y de asociación. La identificación de nuevos

  2. Dynamic characteristics of Great Bronze Buddha of Kamakura using microtremor

    International Nuclear Information System (INIS)

    The second largest bronze Buddha in Japan built in around 1250AD at Kamakura immediately above the focal region of the 1923 Kanto earthquake. Great Buddha of Kamakura has still remained basically its original shape, though it has been suffered several natural disasters as losing its hall. Especially, although the 1703 and 1923 Kanto earthquakes caused settlement and sliding of the basement over 0.3 m., the body has been not suffered serious damage. This statue was casted in order from the bottom with many joints. The joint between the head and the body was noticed because it is reinforced by FRP, Fiber Reinforced Plastic, at the time of the last major repair in 1961. And ingenuity was exercised to fence off the earthquake motion over 400 Gal with sliding the body on the basement, to reduce the load for the neck during earthquake. This is the first example of the earthquake isolation system for cultural properties in Japan. Over 50 years passed after the during earthquake motion, microtremor measurement was conducted. As a result of the primary investigation in 2009, the surrounding ground was estimated that liquefaction was occurred at the front and right sides of the basement and the basement suffered damage as settlement. However, it is considered that the propagation of the earthquake motion for the statue was interrupted because of the liquefaction. Thus, it seems that the damage for the statue itself was prevented because of namely the natural isolation system. Additional y in 2013 microtremor of the statue itself was measured for making clear the connection status between the body and the head.

  3. Spinal arthritis and physical stress at Bronze Age Harappa.

    Science.gov (United States)

    Lovell, N C

    1994-02-01

    This study examines joint changes in the vertebral skeleton in human remains excavated in 1987 and 1988 at Bronze Age Harappa, an urban center of the Indus Valley civilization. The sample consists of 23 complete skeletons from primary burial context, the partial remains of more than 69 other individuals, and hundreds of skeletal elements from secondary context, totalling 3,084 vertebral joint margins and articular surfaces. Marginal bone proliferation, pitting of articular surfaces, eburnation, and ankylosis were scored macroscopically for vertebral body margins and surfaces and posterior apophyseal facet joints. Marginal lipping is far more prevalent on the vertebral bodies than on the apophyseal facets and surface pitting is also more frequent on vertebral bodies although its expression is relatively low overall. Cervical vertebrae in this sample exhibit the same amount of marginal new bone and much more surface pitting of the vertebral bodies than do either thoracic or lumbar vertebrae; the cervical segment also exhibits the most severe expressions of both types of lesions. In addition, although the frequencies of cervical and lumbar posterior facet involvement are similar, the cervical facets exhibit much more severe lipping as well as the only cases of eburnation and ankylosis. Pitting of the posterior facets is most common in the lumbar segment, but the cervical examples are the only severe cases. It is proposed that the severe joint changes in the cervical spine result from trauma, perhaps accumulated microtrauma from activity stresses. There are no age or sex associated patterns in the frequency of arthritis although this result may be influenced by the small proportions of the total sample for which age and sex could be determined. PMID:8147433

  4. Neutron resonance capture and neutron diffraction analysis of Roman bronze water taps

    International Nuclear Information System (INIS)

    Parts of four Roman bronze water taps, excavated in The Netherlands consisting of two cylinders and two cylinder housings, were nondestructively investigated by neutron resonance capture analysis and by time-of-flight neutron diffraction. The two complementary neutron methods have been, for the first time, combined for providing a comprehensive alloy characterization of intact, undisturbed archaeological bronze objects. Bulk chemical analyses and phase analyses of the copper alloys were carried out in order to establish relations and differences among the taps, and to address questions of standardization and fabrication. (author)

  5. Vegetation reconstruction of Bronze Age by using microscopic structure of charcoals

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The microscopic structure of charcoals was determined in two sites of Bronze Age, Chifeng area by using the scanning electronic microscope. The results showed that these charcoals are all timbers of Mongolian oak (Quercus mongolica). It has powerful climatic indicative significance. Based on the assemblage of pollen composition, their eco-climatic index and character of community, the vegetation reconstruction of Bronze Age was obtained. The reconstruction showed that the zonal vegetation was Mongolian oak forest and Chinese pine forest in the loess hills in the Chifeng area, which suggested that the climatic condition was warmer and wetter at that time than present time.

  6. Nomadic pastoralism in the Early Bronze Age of the central Balkans evaluation of background knowledge

    Directory of Open Access Journals (Sweden)

    Porčić Marko

    2008-01-01

    Full Text Available The aim of the paper is to examine background knowledge about the orga­nizational properties of mobile pastoral groups in order to assess the likelihood of the existence of pastoral nomads in the Early Bronze Age in the central Balkans. The patterning found by A. L. Johnson (2002 is taken as a point of departure for the cross-cultural analysis conducted in this study. Johnson’s findings are in the main corroborated. Acquired knowledge about the workings of pastoral societies suggests that highly mobile pastoral groups should not be expected in the Early Bronze Age of the central Balkans.

  7. Multielement analysis of archaic Chinese bronze and antique coins by fast neutron activation analysis

    International Nuclear Information System (INIS)

    Samples of archaic bronze were investigated by fast neutron activation analysis using both the absolute and relative method. The components Cu, Zn, Sn and Pb were determined quantitatively. For nondestructive analysis of antique Chinese coins the samples had to be irradiated. The activation reactions, the evaluation of the elemental concentrations and the accuracy of the results are discussed. The data were corrected for γ-ray self-absorption in the samples and summing of coincident γ-rays in the detector. According to reported typical compositions of Chinese bronze from different dynasties, the age of the samples has been derived from the results obtained. (author) 18 refs.; 3 figs.; 7 tabs

  8. Elemental analysis of ancient Chinese bronze artifacts with external-beam PIXE

    International Nuclear Information System (INIS)

    External-beam PIXE has been applied for the determination of the elemental composition of ancient Chinese bronze artifacts. Characteristic x-ray spectra from the samples bombarded with protons of 3 MeV have been measured with a HPGe detector. At each sample three spots were irradiated per run. Results of measurements on three fragments of bronze drinking vessels and helmet of Chinese ancient Chou and Shang dynasties (17th-8th century B.C.) are presented. To check the analytical method, we have also made measurements on the elemental composition of some modern coins. The results are discussed. (author)

  9. O bronze final na região de Mértola

    OpenAIRE

    BARROS, Pedro de

    2012-01-01

    Mértola fica localizada num local com boa defensibilidade, no final do longo estuário do Rio Guadiana no Sudoeste Peninsular entre uma peneplanicíe e os vales encaixados, onde as linhas de água subsidiárias têm o seu percurso. A ocupação do Bronze Final de Mértola é revelada pela presença de cerâmica com ornatos brunidos, formas cerâmicas manuais, cerâmica frequentemente designada "tipo Carambolo" e um exemplar de foice em bronze do "tipo Rocanes". Apesar de serem poucos os elementos, estes r...

  10. Bronze Age moss fibre garments from Scotland – the jury’s out

    OpenAIRE

    Harris, Susanna; Gleba, Margarita

    2015-01-01

    In the light of recent discoveries of early to middle Bronze Age burials with mats and fibrous material in Scotland, for example at Langwell farm and Forteviot, it was deemed timely to re-evaluate earlier finds of this period, several of which were discovered and initially reported on nearly a century ago. As part of this research it was noted that three Bronze Age finds from the old literature were reported as clothing or shrouds made of hair moss (Polytrichum commune). Three of these are r...

  11. Corrosion Behaviour of Alpha Phase Aluminium Bronze Alloy in Selected Environments

    OpenAIRE

    Oluwayomi BALOGUN; Joseph BORODE; Kenneth ALANEME; Michael BODUNRIN

    2014-01-01

    This research investigated the corrosion behaviour of aluminium (8 wt %) bronze alloys produced via sand casting in acidic, alkaline, and marine environments. The aluminium bronze was produced from aluminium (6063) alloy and copper scraps by sand casting according to European standard specification (UNS. C61400-CuAl8), after which they were cut into smaller sizes and immersed in the selected corrosive media for corrosion test investigation. H2SO4, NaCl, NaOH, and HCl of 0.1 M, 0.2 M, 0.3 M, 0...

  12. Craftmanship, Production and Distribution of Metalwork in the Early and Middle Northern Bronze Age

    DEFF Research Database (Denmark)

    Nørgaard, Heide Wrobel

    Workshops and their sphere of influence is an important factor in the identification of social groups who are related to what we term workshop. Here the specialization within the workshop based on certain forms and behaviours can be linked to the knowledge of social groups. Statements about the...... possible to compare these traits between different bronze objects. Using a group of bronze objects who are already critically analyzed with regard to the formal characteristics gives a unique opportunity to recognize the workshops and their distribution areas and will be the base of the project....

  13. Nanocomposite anode materials for sodium-ion batteries

    Science.gov (United States)

    Manthiram, Arumugam; Kim Il, Tae; Allcorn, Eric

    2016-06-14

    The disclosure relates to an anode material for a sodium-ion battery having the general formula AO.sub.x--C or AC.sub.x--C, where A is aluminum (Al), magnesium (Mg), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), zirconium (Zr), molybdenum (Mo), tungsten (W), niobium (Nb), tantalum (Ta), silicon (Si), or any combinations thereof. The anode material also contains an electrochemically active nanoparticles within the matrix. The nanoparticle may react with sodium ion (Na.sup.+) when placed in the anode of a sodium-ion battery. In more specific embodiments, the anode material may have the general formula M.sub.ySb-M'O.sub.x--C, Sb-MO.sub.x--C, M.sub.ySn-M'C.sub.x--C, or Sn-MC.sub.x--C. The disclosure also relates to rechargeable sodium-ion batteries containing these materials and methods of making these materials.

  14. Low sodium level

    Science.gov (United States)

    Low sodium level is a condition in which the amount of sodium (salt) in the blood is lower than normal. ... Sodium is found mostly in the body fluids outside the cells. It is very important for maintaining ...

  15. Sodium and Food Sources

    Science.gov (United States)

    ... Disease Cholesterol High Blood Pressure Million Hearts® WISEWOMAN Sodium and Food Sources Recommend on Facebook Tweet Share ... food [PDF-867K] and how to reduce sodium. Sodium Reduction Is Challenging Types of food matter: More ...

  16. Mesoporous amorphous tungsten oxide electrochromic films: a Raman analysis of their good switching behavior

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Mesoporous films exhibit better electrochemical kinetics compared to the dense films. • Mesoporous films exhibit better reversibility compared to the dense films. • Li+cations disrupt WO3 network in a reversible way in the mesoporous film. • Li+ irreversibly intercalate in the voids of crystallites in the dense film. - Abstract: The intercalation and de-intercalation of lithium cations in electrochromic tungsten oxide thin films are significantly influenced by their structural and surface characteristics. In this study, we prepared two types of amorphous films via the sol-gel technique: one dense and one mesoporous in order to compare their response upon lithium intercalation and de-intercalation. According to chronoamperometric measurements, Li+ intercalates/de-intercalates faster in the mesoporous film (24s/6s) than in the dense film (48s/10s). The electrochemical measurements (cyclic voltammetry and chronoamperometry) also showed worse reversibility for the dense film compared to the mesoporous film, giving rise to important Li+ trapping and remaining coloration of the film. Raman analysis showed that the mesoporous film provides more accessible and various W-O surface bonds for Li+ intercalation. On the contrary, in the first electrochemical insertion and de-insertion in the dense film, Li+ selectively reacts with a few surface W-O bonds and preferentially intercalates into pre-existing crystallites to form stable irreversible LixWO3 bronze

  17. One-Step Synthesis of Titanium Oxyhydroxy-Fluoride Rods and Research on the Electrochemical Performance for Lithium-ion Batteries and Sodium-ion Batteries

    OpenAIRE

    Li, Biao; Gao, Zhan; Wang, Dake; Hao, Qiaoyan; Wang, Yan; Wang, Yongkun; Tang, Kaibin

    2015-01-01

    Titanium oxyhydroxy-fluoride, TiO0.9(OH)0.9F1.2 · 0.59H2O rods with a hexagonal tungsten bronze (HTB) structure, was synthesized via a facile one-step solvothermal method. The structure, morphology, and component of the products were characterized by X-ray powder diffraction (XRD), thermogravimetry (TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), ion chromatograph,...

  18. Growth of tungsten oxide on carbon nanowalls templates

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hua, E-mail: wanghua@dlou.edu.cn [Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024 (China); College of Fisheries and Life Science, Dalian Ocean University, Dalian 116023 (China); Su, Yan [Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024 (China); Chen, Shuo, E-mail: shuochen@dlut.edu.cn [Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024 (China); Quan, Xie [Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024 (China)

    2013-03-15

    Highlights: ► Tungsten oxide deposited on carbon nanowalls by hot filament chemical vapor deposition technique. ► This composite has two-dimensional uniform morphology with a crystalline structure of monoclinic tungsten trioxide. ► Surface photoelectric voltage measurements show that this product has photoresponse properties. - Abstract: In the present work we present a simple approach for coupling tungsten oxide with carbon nanowalls. The two-dimensional carbon nanowalls with open boundaries were grown using plasma enhanced hot filament chemical vapor deposition, and the subsequent tungsten oxide growth was performed in the same equipment by direct heating of a tungsten filament. The tungsten oxide coating is found to have uniform morphology with a crystalline structure of monoclinic tungsten trioxide. Surface photoelectric voltage measurements show that this product has photoresponse properties. The method of synthesis described here provides an operable route to the production of two-dimensional tungsten oxide nanocomposites.

  19. Mathematical Modelling of Process of Fluoration of Metal Tungsten

    Directory of Open Access Journals (Sweden)

    Brendakov Roman V.

    2016-01-01

    Full Text Available Wide use of products from metal tungsten in various branches of a national economy is caused by unique properties of this metal. By means of physical and mathematical modelling of process of receiving gaseous hexafluoride of tungsten it is possible to solve a problem of creation of import-substituting technology of processing of metal tungsten. The fluoride technology of processing of tungsten allows to put various coverings and to make products of tungsten of a various form which can't be received by traditional methods. Fluoride technology of processing of tungsten it is possible to present in the form sequences of two processes, process of fluorination of metal tungsten and process of restoration of fluorides of tungsten hydrogen.

  20. Principles of the alloying of tungsten and development of the manufacturing technology for the tungsten alloys

    International Nuclear Information System (INIS)

    Tungsten alloys (Tm = 3410 oC) are intended for service in reducing and neutral media or in vacuum at temperatures and loads that are too high to be suitable for alloys based on more low-melting metals. The disadvantage of tungsten as bcc transition metal of IV group is its susceptibility to cold brittleness (low plasticity at temperatures below the ductile-brittle transition temperature Td/b). The aim of the present work was to develop the principle of the design of tungsten-based structural alloys and their manufacturing and treatment processes providing the production of high-strength high-temperature tungsten-based materials having a satisfactory low-temperature plasticity and workability both in thin sections and in large-scale articles. To achieve this goal, it was necessary to solve the following problems: 1. to elaborate the methods controlling the cold brittleness of tungsten with allowance for the factors responsible for this damage and with reference to the production method; 2. to elaborate the methods improving strength and high-temperature strength with allowance for the acceleration of diffusion processes in bcc metals at temperatures above 0.6 Tm and for the absence of 'more sluggish' alloying elements (AE) than the most refractory metal tungsten; 3. to elaborate the methods of the uniform distribution of AE and strengthening phases in conventionally melted or powder tungsten alloys for the stabilization of required phase composition and structural state and the required combination of the properties of tungsten-based materials; 4. to elaborate the possibility and reasonability to use one ore another type of alloying and microstructure formation upon the manufacturing and thermoplastic treatment with reference to the type and destination of semiproducts or articles produced from tungsten-based alloys or composites. (author)

  1. Bibliographic study on the recovery tungsten

    International Nuclear Information System (INIS)

    Because of the importance of tungsten as a metal and its availability in Algerian ores, many prospective missions have been organized in the hoggar region since the country has recovered its independence and autonomy in order to extract the metal. The tungsten ores which are found in the hoggar are essentially composed of wolframite. With a 100000 tons per year as a production rate and a content of W03 + Sn very rarely greater than 1% the hoggar occupies a honorrable place among the regions which are well know throughout the world to produce tungsten. The are valorization technique which has been developed is mainly a gravimetric in humid media. It consists of a local preconcentration giving birth to a preconcentrated sample that is afterwards transferred to and dealt with a central plant where the final product is obtained

  2. TPV Systems with Solar Powered Tungsten Emitters

    International Nuclear Information System (INIS)

    A solar TPV generator development and characterization are presented. A double stage sunlight concentrator ensures 4600x concentration ratio. TPV modules based on tungsten emitters and GaSb cells were designed, fabricated and tested at indoor and outdoor conditions. The performance of tungsten emitter under concentrated solar radiation was analyzed. Emitter temperatures in the range of 1400-2000 K were measured, depending on the emitter size. The light distribution in the module has been characterized, 1x1 cm GaSb TPV cells were fabricated with the use of the Zn-diffusion and LPE technologies. The cell efficiency of 19% under illumination by a tungsten emitter (27% under spectra cut-off at λ > 1820 nm) heated up to 1900-2000 K had been derived from experimentally measured PV parameters. The series connection of PV cells was ensured by the use of BeO ceramics. The possibilities of system performance improvement are discussed

  3. Element 74, the Wolfram Versus Tungsten Controversy

    Energy Technology Data Exchange (ETDEWEB)

    Holden,N.E.

    2008-08-11

    Two and a quarter centuries ago, a heavy mineral ore was found which was thought to contain a new chemical element called heavy stone (or tungsten in Swedish). A few years later, the metal was separated from its oxide and the new element (Z=74) was called wolfram. Over the years since that time, both the names wolfram and tungsten were attached to this element in various countries. Sixty years ago, IUPAC chose wolfram as the official name for the element. A few years later, under pressure from the press in the USA, the alternative name tungsten was also allowed by IUPAC. Now the original, official name 'wolfram' has been deleted by IUPAC as one of the two alternate names for the element. The history of this controversy is described here.

  4. Strangers in a strange land: Egyptians in southern Palestine during the Bronze Age

    Directory of Open Access Journals (Sweden)

    Rachael Sparks

    2002-10-01

    Full Text Available When the Institute of Archaeology was formally established in 1937, it became responsible for housing Sir Flinders Petrie’s collection of archaeological material from Palestine. This unique inheritance has great value as a research collection, as its curator demonstrates here in her discussion of interaction between Egypt and Palestine in the Bronze Age.

  5. La médaille de bronze du CNRS à un physicien clermontois

    CERN Document Server

    2005-01-01

    Evey year, the National center for scientific research (CNRS), rewards around fifty of searchers at various stages of their career. The bronze medal rewards the first work of a searcher, making of him a specialist in his field; Philippe Crochet was awarded this medal

  6. Study on surface properties of gilt-bronze artifacts, after Nd:YAG laser cleaning

    International Nuclear Information System (INIS)

    As numerous pores are formed at plating gilt-bronze artifacts, the metal underlying the gold is corroded and corrosion products are formed on layer of gold. Through this study, the surfaces of gilt-bronze are being investigated before and after the laser irradiation to remove corrosion products of copper by using Nd:YAG laser. For gilt-bronze specimens, laser and chemical cleaning were performed, and thereafter, surface analysis with SEM-EDS, AFM, and XPS were used to determine the surface characteristics. Experimental results show that chemical cleaning removes corrosion products of copper through dissolution but it was not removed uniformly and separated the metal substrate and the gold layer. Nevertheless, through laser cleaning, some of the corrosions were removed with some damaged areas due to certain conditions and brown residues remained. Brown residues were copper corrosion products mixed with soil left within the gilt layer. It was due to surface morphology of uneven and rough gilt layer. Hence, they did not react effectively to laser beams, and thus, remained as residues. The surface properties of gilt-bronze should be thoroughly investigated with various surface analyses to succeed in laser cleaning without damages or residues.

  7. Study on surface properties of gilt-bronze artifacts, after Nd:YAG laser cleaning

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyeyoun [Division of Restoration Technology, National Research Institute of Cultural Heritage, Daejeon (Korea, Republic of); Cho, Namchul, E-mail: nam1611@hanmail.net [Department of Cultural Heritage Conservation Science, Kongju National University, Gongju, 314-701 (Korea, Republic of); Lee, Jongmyoung [Laser Engineering Group, IMT Co. Ltd, Gyeonggi (Korea, Republic of)

    2013-11-01

    As numerous pores are formed at plating gilt-bronze artifacts, the metal underlying the gold is corroded and corrosion products are formed on layer of gold. Through this study, the surfaces of gilt-bronze are being investigated before and after the laser irradiation to remove corrosion products of copper by using Nd:YAG laser. For gilt-bronze specimens, laser and chemical cleaning were performed, and thereafter, surface analysis with SEM-EDS, AFM, and XPS were used to determine the surface characteristics. Experimental results show that chemical cleaning removes corrosion products of copper through dissolution but it was not removed uniformly and separated the metal substrate and the gold layer. Nevertheless, through laser cleaning, some of the corrosions were removed with some damaged areas due to certain conditions and brown residues remained. Brown residues were copper corrosion products mixed with soil left within the gilt layer. It was due to surface morphology of uneven and rough gilt layer. Hence, they did not react effectively to laser beams, and thus, remained as residues. The surface properties of gilt-bronze should be thoroughly investigated with various surface analyses to succeed in laser cleaning without damages or residues.

  8. Dating Archaeological Copper/Bronze Artifacts by Using the Voltammetry of Microparticles

    OpenAIRE

    Doménech-Carbó, Antonio; Doménech-Carbó, Maria Teresa; Capelo, Sofia; Pasíes, Trinidad; Martínez-Lázaro, Isabel

    2014-01-01

    A method for dating copper/bronze archaeological objects aged in atmospheric environments is proposed based on the specific signals for cuprite and tenorite corrosion products measured through the voltammtry of microparticles method. The tenorite/cuprite ratio increased with the corrosion time and fitted to a potential law that yielded a calibration curve usable for dating purposes.

  9. Techniques employed in making ancient thin-walled bronze vessels unearthed in Hubei Province, China

    Science.gov (United States)

    Li, Yang; Wu, Taotao; Liao, Lingmin; Liao, Chengwei; Zhang, Lang; Chen, Guantao; Pan, Chunxu

    2013-06-01

    In this paper, two ancient thin-walled bronze vessels unearthed in Anlu County of Hubei Province, China, were studied systematically by using optical microscopy (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), electron backscatter diffraction (EBSD) and nanoindentation system, and also we calculated the Sn diffusion in a Cu substrate based upon the substitutional mechanism at high temperature. The results indicated that the vessels were possibly fabricated using the following processes: (1) alloying the high-tin Cu-Sn bronze; (2) casting the preliminary shape of the vessels; (3) forging the vessels in the temperature range of 586-798 ∘C; (4) simply wiping tinning on the surface of the vessel at high temperature; (5) quenching the vessels to room temperature; and (6) at last, grinding and polishing the surface of the vessels. It seems that the present thin-walled bronze vessels provide an evidence of the spread of thin-walled high-tin bronze technology in China and its surrounding regions.

  10. Isotopic dietary reconstruction of humans from Middle Bronze Age Lerna, Argolid, Greece

    NARCIS (Netherlands)

    Triantaphyllou, S.; Richards, M. P.; Zerner, C.; Voutsaki, S.

    2008-01-01

    This study presents the results of a carbon and nitrogen stable isotope analysis of 39 human bone and 8 animal samples from Middle Bronze Age (or Middle Helladic, MH, ca. 2100-1700 BC) Lerna, Greece. The isotopic data indicate that the humans had a C-3 terrestrial diet while certain individuals appe

  11. Celestial Symbolism in Central European Later Prehistory - Case Studies from the Bronze Age Carpathian Basin

    Science.gov (United States)

    Pásztor, Emília

    It is commonly held that the sun played a particularly important cultural role in later prehistoric Europe. The rise of a general European sun cult has even been suggested for the Bronze Age. During this period, the increasing use of special symbols assumed to represent the sun is easily discernible on different types of archaeological finds.

  12. Antibacterial drugs as corrosion inhibitors for bronze surfaces in acidic solutions

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • All four investigated antibacterial drugs act as corrosion inhibitors for bronze surface. • In the presence of antibiotics, a 3RC electric circuit simulates the corrosion system. • The electrochemical results indicate as best inhibitors Doxy, followed by Strepto. • HOMO–LUMO energy gap increases in the order: Doxy > Strepto > Cipro > Amoxi. • The thin protective film on bronze is reinforced by the presence of the antibiotics. - Abstract: The present study is aiming to investigate the effect of four antibiotics (amoxicillin, ciprofloxacin, doxycycline and streptomycin,) belonging to different classes of antibacterial drugs on bronze corrosion in a solution simulating an acid rain (pH 4). Due to their ability to form protective films on the metal surface, the tested antibiotics act as corrosion inhibitors for bronze. The antibiotics were tested at various concentrations in order to determine the optimal concentration range for the best corrosion inhibiting effect. In evaluating the inhibition efficiency, polarization curves, electrochemical impedance spectroscopy, SEM and XPS measurements were used. Moreover, a correlation between the inhibition efficiency of some antibacterial drugs and certain molecular parameters was determined by quantum chemical computations. Parameters like energies EHOMO and ELUMO and HOMO–LUMO energy gap were used for correlation with the corrosion data

  13. Electrodeposition and corrosion resistance of nanocrystalline white bronze (CuSn) coatings

    NARCIS (Netherlands)

    Hovestad, A.; Lekka, M.; Willemsen, R.M.R.; Tacken, R.A.; Bonora, P.L.

    2008-01-01

    For jewellery applications electroplated white bronze (CuSn) was investigated as undercoating for noble metal finishes as alternative to nickel. A strongly acidic plating bath was developed with an organic additive to suppress hydrogen evolution and obtain bright coatings. An electrochemical study o

  14. Upward Sweeps of Empire and City Growth Since the Bronze Age

    OpenAIRE

    Chris Chase-Dunn; Alexis Alvarez; Hiroko Inoue; Richard Niemeyer; Anders Carlson; Ben Fierro; Kirk Lawrence

    2006-01-01

    Abstract: This paper uses quantitative estimates of the sizes of cities and empires to tentatively identify upward sweeps in which uniquely large cities and empires emerged in the Central Political/military network since the Bronze Age, and it formulates a causal model to explain both the cyclical rise and fall of cities and empires and the upward sweep

  15. Characterisation of a Proto-historic bronze collection by micro-EDXRF

    Energy Technology Data Exchange (ETDEWEB)

    Figueiredo, Elin, E-mail: elin@itn.pt [IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Estrada Nacional 10, 2686-953 Sacavém (Portugal); CENIMAT/I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Araújo, M. Fátima [IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Estrada Nacional 10, 2686-953 Sacavém (Portugal); Silva, Rui J.C. [CENIMAT/I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Vilaça, Raquel [CEAUCP-FCT, Instituto de Arqueologia, Departamento de História, Arqueologia e Artes, Faculdade de Letras, Universidade de Coimbra, Palácio de Sub-Ripas, 3000-395 Coimbra (Portugal)

    2013-02-01

    Highlights: ► A collection of Proto-historic metal artefacts was analysed by micro-EDXRF. ► Composition of major and minor elements has been determined. ► Artefacts were manufactured in a bronze alloy with a low impurity pattern. ► The alloy shows parallels with indigenous Late Bronze Age Iberian productions. -- Abstract: Studies concerning European Proto-historic metallic artefacts can provide important clues about technological transfers during a period of time characterised by diverse cultural interactions. A collection of Proto-historic metallic artefacts from Medronhal (western Iberian Peninsula) composed by rings, bracelets and a fibula related to different cultural affiliations were investigated by micro-EDXRF to provide a major and a minor elemental characterisation. Results show that the Medronhal collection was manufactured in a Cu–Sn alloy (binary bronze) with similar Sn contents among the various types of artefacts and a low impurity pattern. Results of the type and quality of metal were compared to other artefact collections to infer about metallurgical parallels. Strong parallels with indigenous Late Bronze Age Iberian metallurgical productions were found.

  16. Cold Spraying of Cu-Al-Bronze for Cavitation Protection in Marine Environments

    Science.gov (United States)

    Krebs, S.; Gärtner, F.; Klassen, T.

    2015-01-01

    Traveling at high speeds, ships have to face the problem of rudder cavitation-erosion. At present, the problem is countered by fluid dynamically optimized rudders, synthetic, and weld-cladded coatings on steel basis. Nevertheless, docking and repair is required after certain intervals. Bulk Cu-Al-bronzes are in use at ships propellers to withstand corrosion and cavitation. Deposited as coatings with bulk-like properties, such bronzes could also enhance rudder life times. The present study investigates the coating formation by cold spraying CuAl10Fe5Ni5 bronze powders. By calculations of the impact conditions, the range of optimum spray parameters was preselected in terms of the coating quality parameter η on steel substrates with different temperatures. As-atomized and annealed powders were compared to optimize cavitation resistance of the coatings. Results provide insights about the interplay between the mechanical properties of powder and substrate for coating formation. Single particle impact morphologies visualize the deformation behavior. Coating performance was assessed by analyzing microstructures, bond strength, and cavitation resistance. These first results demonstrate that cold-sprayed bronze coatings have a high potential for ensuring a good performances in rudder protection. With further optimization, such coatings could evolve towards a competitive alternative to existing anti-cavitation procedures.

  17. The Agro Pontino region, refuge after the Early Bronze Age Avellino eruption of Mount Vesuvius, Italy?

    NARCIS (Netherlands)

    C. Bakels; J. Sevink; W. Kuijper; H. Kamermans

    2015-01-01

    In recent years it was discovered that the Middle to Late Holocene infi ll of the Agro Pontino graben (Central Italy) held a tephra layer originating from the Avellino eruption of the Vesuvius volcano. The eruption is dated to 1995 ± 10 calBC and took therefore place during the Early Bronze Age. Thi

  18. 76 FR 40402 - Matthews International Corporation, Bronze Division, Kingwood, WV; Notice of Negative...

    Science.gov (United States)

    2011-07-08

    ..., Kingwood, WV; Notice of Negative Determination on Reconsideration On January 28, 2011, the Department of..., 2011 (76 FR 7584). Workers were engaged in the production of cast bronze memorial products. The initial investigation resulted in a negative determination based on the findings that, during the relevant period,...

  19. Antibacterial drugs as corrosion inhibitors for bronze surfaces in acidic solutions

    Energy Technology Data Exchange (ETDEWEB)

    Rotaru, Ileana [Department of Chemical Engineering, “Babes-Bolyai” University, 11 Arany-Janos St., 400028 Cluj-Napoca (Romania); Varvara, Simona, E-mail: svarvara@uab.ro [Department of Exact Sciences and Engineering, “1 Decembrie 1918” University, 11-13 Nicolae Iorga St., 510009 Alba Iulia (Romania); Gaina, Luiza [Department of Chemical Engineering, “Babes-Bolyai” University, 11 Arany-Janos St., 400028 Cluj-Napoca (Romania); Muresan, Liana Maria, E-mail: limur@chem.ubbcluj.ro [Department of Chemical Engineering, “Babes-Bolyai” University, 11 Arany-Janos St., 400028 Cluj-Napoca (Romania)

    2014-12-01

    Graphical abstract: - Highlights: • All four investigated antibacterial drugs act as corrosion inhibitors for bronze surface. • In the presence of antibiotics, a 3RC electric circuit simulates the corrosion system. • The electrochemical results indicate as best inhibitors Doxy, followed by Strepto. • HOMO–LUMO energy gap increases in the order: Doxy > Strepto > Cipro > Amoxi. • The thin protective film on bronze is reinforced by the presence of the antibiotics. - Abstract: The present study is aiming to investigate the effect of four antibiotics (amoxicillin, ciprofloxacin, doxycycline and streptomycin,) belonging to different classes of antibacterial drugs on bronze corrosion in a solution simulating an acid rain (pH 4). Due to their ability to form protective films on the metal surface, the tested antibiotics act as corrosion inhibitors for bronze. The antibiotics were tested at various concentrations in order to determine the optimal concentration range for the best corrosion inhibiting effect. In evaluating the inhibition efficiency, polarization curves, electrochemical impedance spectroscopy, SEM and XPS measurements were used. Moreover, a correlation between the inhibition efficiency of some antibacterial drugs and certain molecular parameters was determined by quantum chemical computations. Parameters like energies E{sub HOMO} and E{sub LUMO} and HOMO–LUMO energy gap were used for correlation with the corrosion data.

  20. Partially fluorinated oxo-alkoxide tungsten(VI) complexes as precursors for deposition of WOx nanomaterials.

    Science.gov (United States)

    Bonsu, Richard O; Kim, Hankook; O'Donohue, Christopher; Korotkov, Roman Y; McClain, K Randall; Abboud, Khalil A; Ellsworth, Ashley A; Walker, Amy V; Anderson, Timothy J; McElwee-White, Lisa

    2014-06-28

    The partially fluorinated oxo-alkoxide tungsten(VI) complexes WO(OR)4 [4; R = C(CH3)2CF3, 5; R = C(CH3)(CF3)2] have been synthesized as precursors for chemical vapour deposition (CVD) of WOx nanocrystalline material. Complexes 4 and 5 were prepared by salt metathesis between sodium salts of the fluoroalkoxides and WOCl4. Crystallographic structure analysis allows comparison of the bonding in 4 and 5 as the fluorine content of the fluoroalkoxide ligands is varied. Screening of as a CVD precursor by mass spectrometry and thermogravimetric analysis was followed by deposition of WOx nanorods. PMID:24821611

  1. Determination of scandium in wolframite and in the residues obtained after the extraction of tungsten.

    Science.gov (United States)

    Gokhale, Y W; Bhat, T R

    1967-03-01

    The separation of scandium from iron and manganese by extraction with TBP from hydrochloric acid was studied in detail and this method was applied to the estimation of scandium in wolframite and its residues. The method consists of the extraction of tungsten from the wolframite with sodium carbonate, dissolution of the residue in hydrochloric acid and preferential extraction of iron and scandium from hydrochloric acid, stripping of the scandium with 8 M hydrochloric acid and re-extraction of accompanying iron with fresh TBP, precipitation of scandium with ammonia in presence of ammonium chloride, and final purification of the scandium by TBP extraction. PMID:18960113

  2. Randomised controlled trials of staged teaching for basic life support. 1. Skill acquisition at bronze stage.

    Science.gov (United States)

    Assar, D; Chamberlain, D; Colquhoun, M; Donnelly, P; Handley, A J; Leaves, S; Kern, K B

    2000-06-01

    We have investigated a method of teaching community CPR in three stages instead of in a single session. These have been designated bronze, silver, and gold stages. The first involves only opening of the airway and chest compression with back blows for choking, the second adds ventilation in a ratio of compressions to breaths of 50:5, and the third is a conversion to conventional CPR. In a controlled randomised trial of 495 trainees we compared the performance in tests immediately after instruction of those who had received a conventional course and those who had had the simpler bronze level tuition. The tests were based on video recordings of simulated resuscitation scenarios and the readouts from recording manikins. Differences occurred as a direct consequence of ventilation being required in one group and not the other, some variation probably followed from unforeseen minor changes in the way that instruction was given, whilst others may have followed from the greater simplicity in the new method of training. A careful approach was followed by slightly more trainees in the conventional group whilst appreciably more in the bronze group remembered to shout for help (44% vs. 71%). A clear advantage was also seen for bronze level training in terms of those who opened the airway as taught (35% vs. 56%), for checking breathing (66% vs. 88%), and for mentioning the need to phone for an ambulance (21% vs. 32%). Little difference was observed in correct or acceptable hand position between the conventional group who were given detailed guidance and the bronze group who were instructed only to push on the centre of the chest. The biggest differences related to the number of compressions given. The mean delay to first compression was 63 s and 34 s, and the mean duration of pauses between compressions was 16 s and 9 s, respectively. Average performed rates were similar in the two groups, but more in the conventional group compressed too slowly whereas more in the bronze group

  3. The effects of chemical oxide on the deposition of tungsten by the silicon reduction of tungsten hexaflouride

    International Nuclear Information System (INIS)

    The effects of thin (chemical) oxide grown during the chemical cleaning of silicon wafers on the silicon reduction of tungsten hexaflouride have been investigated. Unlike tungsten deposition on samples without the chemical oxide, deposition thickness on those with the chemical oxide was found to be substantially thicker. Inspection by cross sectional SEM and TEM revealed the existence of micro-channels penetrating the tungsten film, reaching all the way from the surface of the film to the tungsten/silicon interface. These channels enable tungsten hexaflouride to reach the substrate, thus causing unlimited tungsten growth. Because the silicon surface participates directly in the reaction, it should be expected that the reaction itself be influenced by the chemical treatment of the surface prior to tungsten deposition. Under certain deposition conditions, and for properly prepared silicon surfaces, silicon reduction is known to result in self limiting tungsten deposition

  4. Ultra-broad band absorber made by tungsten and aluminium

    Science.gov (United States)

    Wang, Wei; Zhao, Ding; Li, Qiang; Qiu, Min

    2016-01-01

    A broadband absorber comprising tungsten cubic arrays, a alumina layer and a tungsten film, is numerically and experimentally investigated, which exhibits near-unity absorption of visible and near-infrared light from 400 nm to 1150 nm. Benefiting from high melting points of tungsten and alumina, this device has great application potential in solar cells and thermal emission.

  5. Extraction of tungsten from bicarbonate solutions by MTAA salts

    International Nuclear Information System (INIS)

    Results are presented on investigations of tungsten extraction from bicarbonate reextracts prepared during reprocessing of carbonate solutions of autoclave-carbonate leaching of mineral raw material and so through ammonium reextraction of polymeric tungsten compounds with preparation of concentrated by tungsten reextracts for separation of conditioned ammonium paratungstate. Variants of proposed technological scheme are discussed

  6. Tungsten potentiodynamic behaviour in sulfuric acid solutions

    International Nuclear Information System (INIS)

    The behaviour of a tungsten electrode to cyclic voltametry as a perturbation technique was studied. Tests were carried out in 1M H2SO4 (25.0 + - 0.2)0C and using a three electrode conventional cell. The electrode potential was measured in relation to a saturated calomel electrode connected to a Luggin capillary. The working electrode consisted of a tungsten wire, of spectroscopic purity, having 0.6 cm2 geometric area and a platinum counter-electrode. Considerations about the conditions and feasibility of using such an electrode for electrochemical and electrocatalytic studied are made. (C.L.B.)

  7. Microstructural evolution of tungsten oxide thin films

    International Nuclear Information System (INIS)

    Tungsten oxide thin films are of great interest due to their promising applications in various optoelectronic thin film devices. We have investigated the microstructural evolution of tungsten oxide thin films grown by DC magnetron sputtering on silicon substrate. The structural characterization and surface morphology were carried out using X-ray diffraction and Scanning Electron Microscopy (SEM). The as deposited films were amorphous, where as, the films annealed above 400 deg. were crystalline. In order to explain the microstructural changes due to annealing, we have proposed a 'instability wheel' model for the evolution of the microstructure. This model explains the transformation of mater into various geometries within them selves, followed by external perturbation.

  8. Grain refinement of bronze alloy by equal-channel angular pressing (ECAP and its effect on corrosion behaviour

    Directory of Open Access Journals (Sweden)

    M.M. Sadawy

    2016-08-01

    Full Text Available The corrosion behaviour of bronze alloy prepared by equal channel angular pressing (ECAP was investigated in 3.5 wt. % NaCl solution. Immersion corrosion tests and different electrochemical techniques were carried out. The results showed that ECAPed bronze samples exhibited higher corrosion resistance compared with the as-cast alloy and the passive current density decreased with increasing number of passes. Moreover, the morphology of alloys indicated that the corrosion damage on the surface of ECAPed bronze was smooth and uniform while the as-cast alloy suffered from selective corrosion.

  9. Calculation of vanadium bronze NaV6O5 electron spectrum by the semiempiric MO LCAO method

    International Nuclear Information System (INIS)

    The electronic spectrum of an oxide vanadium bronze of the type NaV6O15 has been calculated by a modified MVG method, while taking into consideration the Madelung potential and the electrical neutrality of the crystal lattice. Presented are contributions to the crystalline potential across the bronze nodes, made by sublattices of ions V, O, and Na in equivalent positions. It is the comparison of the spectra calculated by the MO LKAO method and in the purely ionic approximation with the experimental ones that enables one to assess more exactly the degree of ionic bonds in the bronze

  10. KKR calculation of the electronic structure of cubic WO/sub 3/ and NaWO/sub 3/

    Energy Technology Data Exchange (ETDEWEB)

    Kopp, L.

    1981-02-01

    Explanation of the metallic properties of the sodium tungsten bronzes has provoked considerable controversy. The main point of contention has concerned which atomic orbitals constitute the conduction band. At least five models have been proposed. These have involved the tungsten 6s states (2), sodium 3p states (3), tungsten 5d (t/sub 2g/) states (4), sodium states (5), and a covalent admixture of oxygen 2p/sub ..pi../ and tungsten 5d (t/sub 2g/) states (6) in the conduction process.

  11. Selection of the temperature of casting the bronzes to plaster moulds

    Directory of Open Access Journals (Sweden)

    B. Pisarek

    2009-07-01

    Full Text Available The results of the investigations of the process of solidification of the bronze CuSn5Zn5Pb5-C (B555 and CuSn10-C (B10 in the hot plaster mould show in the work. For four temperatures of casting: 1200 ° C, 1180 ° C, 1160 ° C and 1140 ° C was conducted the investi-gation: the size of contraction cavity, the fulfillment of the mould cavity formative the casts of test slats about the thickness: 4 mm, 0,8 mm and 0,5 mm. It was conducted the investigation the processes sets in the arrangement the cast-mould and X-ray analysis phase XRD of compound coming into being in indirect layer created among mould and cast in the result of the thermal decomposition of the anhy-drite. It results that the temperature 1140 ° C is the optimum temperature of casting the bronze to hot plaster mould from carried out investiga-tions. The minimum thickness of the wall of the cast from the bronze B555 is 0.5 mm, and from the bronze B10 0.8 mm.The realization of casts about thinner walls is made difficult because of giving off formed gases in the result of the thermal decomposition of the anhydrite. The products of the decomposition of the anhydrite react with elements steps in the chemical composition of studied bronzes, create in the arrangement the cast-mould the indirect layer folded from: sulphites, sulphides, oxides and clean metals (Pb or their compounds, especially Sn and Sb.

  12. Diclofenac sodium.

    Science.gov (United States)

    Small, R E

    1989-08-01

    The pharmacology, pharmacokinetics, clinical efficacy, adverse effects, and dosage of diclofenac sodium are reviewed. Diclofenac, the first nonsteroidal anti-inflammatory agent (NSAID) to be approved that is a phenylacetic acid derivative, competes with arachidonic acid for binding to cyclo-oxygenase, resulting in decreased formation of prostaglandins. The drug has both analgesic and antipyretic activities. Diclofenac is efficiently absorbed from the gastrointestinal tract; peak plasma concentrations occur 1.5 to 2.0 hours after ingestion in fasting subjects. Even though diclofenac has a relatively short elimination half-life in plasma (1.5 hours), it persists in synovial fluid. The drug is metabolized in the liver and is eliminated by urinary and biliary excretion. In clinical trials, diclofenac was as effective as aspirin, diflunisal, indomethacin, sulindac, ibuprofen, ketoprofen, and naproxen in improving function and reducing pain in patients with rheumatoid arthritis. For treatment of osteoarthritis, diclofenac was equivalent in efficacy to aspirin, diflunisal, indomethacin, sulindac, ibuprofen, ketoprofen, naproxen, flurbiprofen, mefenamic acid, and piroxicam. Diclofenac was as effective as indomethacin or sulindac in treating ankylosing spondylitis. The most frequent adverse effects reported for diclofenac were gastrointestinal, but these effects were fewer and less serious than occurred with aspirin or indomethacin; in addition, diclofenac caused fewer central nervous system reactions than indomethacin. Diclofenac is administered in divided doses with meals. The recommended total daily dosage is 100 to 150 mg (osteoarthritis and ankylosing spondylitis) or 150 to 200 mg (rheumatoid arthritis). Diclofenac is effective, but no more so than other NSAIDs. It is structurally distinct and offers another choice in the treatment of rheumatological conditions. PMID:2670397

  13. Liquid sodium pool fires

    International Nuclear Information System (INIS)

    Experimental sodium pool combustion results have led to a definition of the combustion kinetics, and have revealed the hazards of sodium-concrete contact reactions and the possible ignition of organic matter (paint) by hydration of sodium peroxide aerosols. Analysis of these test results shows that the controlling mechanism is sodium evaporation diffusion. (author)

  14. Sodium removal from sodium wetted under sodium ultra sonic scanner

    International Nuclear Information System (INIS)

    Highlights: ► Sodium wetted USUSS was subjected to sodium cleaning by water vapour–CO2 process. ► Hydrogen released during the process was monitored and regulated in safe limit. ► The temperature of USUSS was maintained below 80 °C to prevent caustic corrosion. ► The experiment revealed intricacies involved in the cleaning operation. ► The operational parameters for safe cleaning were optimised. - Abstract: Sodium is used as a coolant in primary and secondary heat transport systems of Liquid Metal cooled Fast Breeder Reactors (LMFBR). The Prototype Fast Breeder Reactor (PFBR) is in advanced stage of construction at Kalpakkam, India. Under Sodium Ultra Sonic Scanner (USUSS) is used to image the components dipped in sodium and more specifically the gap between Sub Assembly (SA) heads and the control plug. This is essential to confirm that no SA is protruding from its position. USUSS has to be qualified in sodium before its use in the reactor. After sodium testing, sodium adhering to the USUSS needs to be removed to prevent reaction with oxygen and moisture present in air when it is taken out. The sodium removal process is based on the use of moist carbon-di-oxide (CO2) at a temperature of about 353 K. The reaction rate is controlled by varying the ratio of CO2 to moisture. Hydrogen released during the reaction of sodium with moisture is continuously monitored to ensure safe limits of hydrogen concentration. This paper describes the details of the experimental setup used in a cleaning pit for the removal of sodium adhering on USUSS and the technical details of the cleaning process.

  15. Aluminum-tungsten fiber composites with cylindrical geometry and controlled architecture of tungsten reinforcement

    OpenAIRE

    Lucchese, Carl Joesph

    2010-01-01

    A aluminum matrix-W rod/wire structural material in support of DARPA initiative BAA 08-23 was developed and its density and mechanical strength ascertained, both being part of the DARPA matrices. Aluminum tubes and four 90 degree cross-ply tungsten fiber layers were arranged such that under extreme static pressure conditions the aluminum would viscoplastically flow into the tungsten arrangement to create a metal matrix composite. It was found that a cold isostatic process induced "Brazilian" ...

  16. Development of tungsten and tungsten alloys for DEMO divertor applications via MIM technology

    Energy Technology Data Exchange (ETDEWEB)

    Blagoeva, D.T., E-mail: blagoeva@nrg.eu [Nuclear Research and Consultancy Group (NRG), Petten (Netherlands); Opschoor, J. [Energy Research Center of the Netherlands (ECN), Petten (Netherlands); Laan, J.G. van der [Nuclear Research and Consultancy Group (NRG), Petten (Netherlands); Sârbu, C. [National Institute for Materials Physics (NIMP), Măgurele-Bucharest (Romania); Pintsuk, G. [Forschungszentrum Jülich GmbH, Jülich (Germany); Jong, M.; Bakker, T.; Ten Pierick, P.; Nolles, H. [Nuclear Research and Consultancy Group (NRG), Petten (Netherlands)

    2013-11-15

    This paper is an overview of the very first results obtained on pure tungsten (W) and oxide dispersed strengthened (ODS) W alloys produced by the Metal Injection Molding (MIM) technique for fusion applications. An extensive mechanical and physical characterization was performed, together with microstructural material investigation. The reported work was accomplished within the framework of the European Fusion Development Agreement work program. The main objective was to develop suitable tungsten grades for structural and armor divertor applications in the future DEMO fusion reactor.

  17. Deuterium retention and release from tungsten

    International Nuclear Information System (INIS)

    The design of a future fusion reactor requires an understanding of the hydrogen isotope (protium, deuterium, and tritium) retention and recycling that will occur during operation. Retention of the hydrogen isotopes is particularly important if the isotope is tritium. Retention of large quantities of tritium in the reactor plasma-facing components increases the fuel costs of the reactor and presents a safety concern. Tungsten is still one of the most promising materials in magnetic fusion energy as a plasma facing material. In the past, it has been used only sparingly due to the problem of excessive radiation losses in the plasma when tungsten is present in the plasma. Tungsten's use in fusion devices will increase in the future. Unfortunately, a prediction of tritium retention during realistic plasma conditions is difficult since there are a few reliable reports about interaction for the simplest interaction of gaseous hydrogen isotopes with tungsten at elevated temperatures. The discrepancy between data is large even for the most important material properties, such as the diffusion constant and solubility. We report the results of long term and precise measurements of hydrogen evolution kinetics at 1000 0C followed by low pressure exposures to deuterium at 500 0C and 1000 0C. (author)

  18. Electrospark doping of steel with tungsten

    Science.gov (United States)

    Denisova, Yulia; Shugurov, Vladimir; Petrikova, Elizaveta; Seksenalina, Malika; Ivanova, Olga; Ikonnikova, Irina; Kunitsyna, Tatyana; Vlasov, Victor; Klopotov, Anatoliy; Ivanov, Yuriy

    2016-01-01

    The paper is devoted to the numerical modeling of thermal processes and the analysis of the structure and properties of the surface layer of carbon steel subjected to electrospark doping with tungsten. The problem of finding the temperature field in the system film (tungsten) / substrate (iron) is reduced to the solution of the heat conductivity equation. A one-dimensional case of heating and cooling of a plate with the thickness d has been considered. Calculations of temperature fields formed in the system film / substrate synthesized using methods of electrospark doping have been carried out as a part of one-dimensional approximation. Calculations have been performed to select the mode of the subsequent treatment of the system film / substrate with a high-intensity pulsed electron beam. Authors revealed the conditions of irradiation allowing implementing processes of steel doping with tungsten. A thermodynamic analysis of phase transformations taking place during doping of iron with tungsten in equilibrium conditions has been performed. The studies have been carried out on the surface layer of the substrate modified using the method of electrospark doping. The results showed the formation in the surface layer of a structure with a highly developed relief and increased strength properties.

  19. Theory and practice of tungsten oxides reduction

    International Nuclear Information System (INIS)

    The paper provides for a critical analysis of a thermograviometric technique for determining the kinetics of tungsten oxides reduction. A mechanism of heterogeneous reduction is proposed which is called discrete-dispersion mechanism. Certain technical and economic data and results of industrial vertical continuous furnace testing are presented

  20. Evidence of hydrogen embrittlement of tungsten carbide.

    Science.gov (United States)

    Kennedy, G C

    1978-02-01

    Tungsten carbide vessels containing materials at high temperature and high pressure are used in many laboratories. We note that any oils at medium to high temperature which can break down and liberate hydrogen cause rapid failure of the pressure vessel, whereas perfluorated kerosenes used as lubricants inside a pressure vessel give sharply increased life of the vessel. PMID:18699072

  1. Joining of Tungsten Armor Using Functional Gradients

    International Nuclear Information System (INIS)

    The joining of low thermal expansion armor materials such as tungsten to high thermal expansion heat sink materials has been a major problem in plasma facing component (PFC) development. Conventional planar bonding techniques have been unable to withstand the high thermal induced stresses resulting from fabrication and high heat flux testing. During this investigation, innovative functional gradient joints produced using vacuum plasma spray forming techniques have been developed for joining tungsten armor to copper alloy heat sinks. A model was developed to select the optimum gradient architecture. Based on the modeling effort, a 2mm copper rich gradient was selected. Vacuum plasma pray parameters and procedures were then developed to produce the functional gradient joint. Using these techniques, dual cooling channel, medium scale mockups (32mm wide x 400mm length) were produced with vacuum plasma spray formed tungsten armor. The thickness of the tungsten armor was up to 5mm thick. No evidence of debonding at the interface between the heat sink and the vacuum plasma sprayed material was observed.

  2. Electrospark doping of steel with tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Denisova, Yulia, E-mail: yukolubaeva@mail.ru; Shugurov, Vladimir, E-mail: shugurov@opee.hcei.tsc.ru [Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences, 634055, Russia, Tomsk, 2/3 Akademicheskiy Ave (Russian Federation); Petrikova, Elizaveta, E-mail: elizmarkova@yahoo.com [Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences, 634055, Russia, Tomsk, 2/3 Akademicheskiy Ave (Russian Federation); National Research Tomsk State University, 36 Lenin Str. Tomsk, 634050 (Russian Federation); Seksenalina, Malika, E-mail: sportmiss@bk.ru [National Research Tomsk Polytechnic University, 30 Lenin Str. Tomsk, 634050 (Russian Federation); Ivanova, Olga, E-mail: ivaov@mail.ru; Ikonnikova, Irina, E-mail: irinaikonnikova@yandex.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq. Tomsk, 634003 (Russian Federation); Kunitsyna, Tatyana, E-mail: kma11061990@mail.ru; Vlasov, Victor, E-mail: rector@tsuab.ru [National Research Tomsk Polytechnic University, 30 Lenin Str. Tomsk, 634050 (Russian Federation); Tomsk State University of Architecture and Building, 2 Solyanaya Sq. Tomsk, 634003 (Russian Federation); Klopotov, Anatoliy, E-mail: klopotovaa@tsuab.ru [National Research Tomsk State University, 36 Lenin Str. Tomsk, 634050 (Russian Federation); Tomsk State University of Architecture and Building, 2 Solyanaya Sq. Tomsk, 634003 (Russian Federation); Ivanov, Yuriy, E-mail: yufi55@mail.ru [Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences, 634055, Russia, Tomsk, 2/3 Akademicheskiy Ave (Russian Federation); National Research Tomsk State University, 36 Lenin Str. Tomsk, 634050 (Russian Federation); National Research Tomsk Polytechnic University, 30 Lenin Str. Tomsk, 634050 (Russian Federation)

    2016-01-15

    The paper is devoted to the numerical modeling of thermal processes and the analysis of the structure and properties of the surface layer of carbon steel subjected to electrospark doping with tungsten. The problem of finding the temperature field in the system film (tungsten) / substrate (iron) is reduced to the solution of the heat conductivity equation. A one-dimensional case of heating and cooling of a plate with the thickness d has been considered. Calculations of temperature fields formed in the system film / substrate synthesized using methods of electrospark doping have been carried out as a part of one-dimensional approximation. Calculations have been performed to select the mode of the subsequent treatment of the system film / substrate with a high-intensity pulsed electron beam. Authors revealed the conditions of irradiation allowing implementing processes of steel doping with tungsten. A thermodynamic analysis of phase transformations taking place during doping of iron with tungsten in equilibrium conditions has been performed. The studies have been carried out on the surface layer of the substrate modified using the method of electrospark doping. The results showed the formation in the surface layer of a structure with a highly developed relief and increased strength properties.

  3. Copper-Tungsten Composites Sprayed by HVOF

    Czech Academy of Sciences Publication Activity Database

    Matějíček, Jiří; Zahálka, F.; Bensch, Jan; Chi, W.; Sedláček, J.

    2008-01-01

    Roč. 17, č. 2 (2008), s. 177-180. ISSN 1059-9630 Institutional research plan: CEZ:AV0Z20430508 Keywords : Thermally sprayed coatings * tungsten * copper * HVOF Subject RIV: JG - Metallurgy Impact factor: 1.200, year: 2008 http://www.springerlink.com/content/120439/

  4. CVD coated tungsten powder composites. Part 2

    International Nuclear Information System (INIS)

    In work sponsored by the Army Materials Technology Laboratory (AMTL), the tungsten composite powders described in Part I were consolidated by hot isostatic pressing (HIP), liquid phase sintering (LPS), and the Ceracon process. THis paper describes the results of consolidation, microstructural characterization, and mechanical properties testing at both quasistatic and elevated strain rates

  5. Proton Induced Effects on Tungsten Powder

    CERN Multimedia

    2012-01-01

    In the HRMT-10 experiment, that took place in HiRadMat facility of CERN/SPS, the effects of a high-power incident proton beam on a tungsten powder target were investigated. In this video, 1.3E11 protons @ 440 GeV are impinging on the target.

  6. Proton Induced Effects on Tungsten Powder

    CERN Multimedia

    2012-01-01

    In the HRMT-10 experiment, that took place in HiRadMat facility of CERN/SPS, the effects of a high-power incident proton beam on a tungsten powder target were investigated. In this video, 1.85E11 protons @ 440 GeV are impinging on the target.

  7. Proton Induced Effects on Tungsten Powder

    CERN Multimedia

    2012-01-01

    In the HRMT-10 experiment, that took place in HiRadMat facility of CERN/SPS, the effects of a high-power incident proton beam on a tungsten powder target were investigated. In this video, 2E11 protons @ 440 GeV are impinging on the target.

  8. Proton Induced Effects on Tungsten Powder

    CERN Multimedia

    HiRadMat facility of CERN/SPS

    2012-01-01

    In the HRMT-10 experiment, that took place in HiRadMat facility of CERN/SPS, the effects of a high-power incident proton beam on a tungsten powder target were investigated. In this video, 1.7E11 protons @ 440 GeV are impinging on the target.

  9. Proton Induced Effects on Tungsten Powder

    CERN Multimedia

    2012-01-01

    In the HRMT-10 experiment, that took place in HiRadMat facility of CERN/SPS, the effects of a high-power incident proton beam on a tungsten powder target were investigated. In this video, 2.64E11 protons @ 440 GeV are impinging on the target.

  10. Computer simulations for thorium doped tungsten crystals

    International Nuclear Information System (INIS)

    Tungsten has the highest melting point among all metals in the periodic table of elements. Furthermore, its equilibrium vapor pressure is by far the lowest at the temperature given. Thoria, ThO2, as a particle dopant, results in a high temperature creep resistant material. Moreover, thorium covered tungsten surfaces show a drastically reduced electronic work function. This results in a tremendous reduction of tip temperatures of cathodes in discharge lamps, and, therefore, in dramatically reduced tungsten vapor pressures. Thorium sublimates at temperatures below those of a typical operating cathode. For proper operation, a diffusional flow of thorium atoms towards the surface has to be maintained. This atomic flux responds very sensitively on the local microstructure, as grain boundaries as well as dislocation cores offer ''short circuit paths'' for thorium atoms. In this work, we address some open issues of thoriated tungsten. A molecular dynamics scheme (MD) is used to derive static as well as dynamic material properties which have their common origin in the atomistic behavior of tungsten and thorium atoms. The interatomic interactions between thorium and tungsten atoms are described within the embedded atom model (EAM). So far, in literature no W-Th interaction potentials on this basis are described. As there is no alloying system known between thorium and tungsten, we have determined material data for the fitting of these potentials using ab-initio methods. This is accomplished using the full potential augmented plane wave method (FLAPW), to get hypothetical, i.e. not occurring in nature, ''alloy'' data of W-Th. In order to circumvent the limitations of classical (NVE) MD schemes, we eventually couple our model systems to external heat baths or volume reservoirs (NVT, NPT). For the NPT ensemble, we implemented a generalization of the variable cell method in combination with the Langevin piston, which results in a set of Langevin equations, i.e. stochastic

  11. Computer simulations for thorium doped tungsten crystals

    Energy Technology Data Exchange (ETDEWEB)

    Eberhard, Bernd

    2009-07-17

    Tungsten has the highest melting point among all metals in the periodic table of elements. Furthermore, its equilibrium vapor pressure is by far the lowest at the temperature given. Thoria, ThO{sub 2}, as a particle dopant, results in a high temperature creep resistant material. Moreover, thorium covered tungsten surfaces show a drastically reduced electronic work function. This results in a tremendous reduction of tip temperatures of cathodes in discharge lamps, and, therefore, in dramatically reduced tungsten vapor pressures. Thorium sublimates at temperatures below those of a typical operating cathode. For proper operation, a diffusional flow of thorium atoms towards the surface has to be maintained. This atomic flux responds very sensitively on the local microstructure, as grain boundaries as well as dislocation cores offer ''short circuit paths'' for thorium atoms. In this work, we address some open issues of thoriated tungsten. A molecular dynamics scheme (MD) is used to derive static as well as dynamic material properties which have their common origin in the atomistic behavior of tungsten and thorium atoms. The interatomic interactions between thorium and tungsten atoms are described within the embedded atom model (EAM). So far, in literature no W-Th interaction potentials on this basis are described. As there is no alloying system known between thorium and tungsten, we have determined material data for the fitting of these potentials using ab-initio methods. This is accomplished using the full potential augmented plane wave method (FLAPW), to get hypothetical, i.e. not occurring in nature, ''alloy'' data of W-Th. In order to circumvent the limitations of classical (NVE) MD schemes, we eventually couple our model systems to external heat baths or volume reservoirs (NVT, NPT). For the NPT ensemble, we implemented a generalization of the variable cell method in combination with the Langevin piston, which results in a

  12. Preliminary Study of Corrosion Status on Bronzes Excavated from Qin Dynasty Tombs at Xinfeng Town in China

    Directory of Open Access Journals (Sweden)

    Qian-li Fu

    2012-01-01

    Full Text Available From 2007 to 2008, many bronze wares of Qin Dynasty were excavated from tombs at Xinfeng town. Being an important finding, these bronze wares attracted people’s attention, especially for their conservation. Therefore, the corrosive products were explored by using Scanning Electron Microscope with Energy Dispersive X-ray Detector (SEM/EDS, X-Ray diffraction (XRD, and Raman spectroscopy (RM, which provided much valuable information on the conservation of these bronze wares. According to tested results, the corrosive products of bronzes were found to be comprised of cuprite (Cu2O, covellite (CuS, lead carbonate (PbCO3, and malachite (CuCO3·Cu(OH2. Meantime, the multilayer corrosive structure was found in some samples due to the cracks in Cu2O layer which had formed many microchannels to promote the material migration.

  13. ITER tungsten divertor design development and qualification program

    Energy Technology Data Exchange (ETDEWEB)

    Hirai, T., E-mail: takeshi.hirai@iter.org [ITER Organization, Route de Vinon sur Verdon, F-13115 Saint Paul lez Durance (France); Escourbiac, F.; Carpentier-Chouchana, S.; Fedosov, A.; Ferrand, L.; Jokinen, T.; Komarov, V.; Kukushkin, A.; Merola, M.; Mitteau, R.; Pitts, R.A.; Shu, W.; Sugihara, M. [ITER Organization, Route de Vinon sur Verdon, F-13115 Saint Paul lez Durance (France); Riccardi, B. [F4E, c/ Josep Pla, n.2, Torres Diagonal Litoral, Edificio B3, E-08019 Barcelona (Spain); Suzuki, S. [JAEA, Fusion Research and Development Directorate JAEA, 801-1 Mukouyama, Naka, Ibaragi 311-0193 (Japan); Villari, R. [Associazione EURATOM-ENEA sulla Fusione, Via Enrico Fermi 45, I-00044 Frascati, Rome (Italy)

    2013-10-15

    Highlights: • Detailed design development plan for the ITER tungsten divertor. • Latest status of the ITER tungsten divertor design. • Brief overview of qualification program for the ITER tungsten divertor and status of R and D activity. -- Abstract: In November 2011, the ITER Council has endorsed the recommendation that a period of up to 2 years be set to develop a full-tungsten divertor design and accelerate technology qualification in view of a possible decision to start operation with a divertor having a full-tungsten plasma-facing surface. To ensure a solid foundation for such a decision, a full tungsten divertor design, together with a demonstration of the necessary high performance tungsten monoblock technology should be completed within the required timescale. The status of both the design and technology R and D activity is summarized in this paper.

  14. ITER tungsten divertor design development and qualification program

    International Nuclear Information System (INIS)

    Highlights: • Detailed design development plan for the ITER tungsten divertor. • Latest status of the ITER tungsten divertor design. • Brief overview of qualification program for the ITER tungsten divertor and status of R and D activity. -- Abstract: In November 2011, the ITER Council has endorsed the recommendation that a period of up to 2 years be set to develop a full-tungsten divertor design and accelerate technology qualification in view of a possible decision to start operation with a divertor having a full-tungsten plasma-facing surface. To ensure a solid foundation for such a decision, a full tungsten divertor design, together with a demonstration of the necessary high performance tungsten monoblock technology should be completed within the required timescale. The status of both the design and technology R and D activity is summarized in this paper

  15. Extractive separation and spectrophotometric determination of tungsten as ferrocyanide

    International Nuclear Information System (INIS)

    Tungsten, in amounts ranging from micrograms to milligrams, can be extracted into isoamyl alcohol, as the tungsten(V) ferrocyanide complex obtained by reduction of tungsten(VI) with tin(II) in 4M hydrochloric acid containing ferrocyanide. It can thus be separated from iron, cobalt, chromium, manganese, arsenic, antimony, bismuth, silicon, calcium and copper, their precipitation being prevented by addition of glycerol and, in the case of iron, sulphosalicylic acid. Molybdenum, vanadium and nickel are not separated from tungsten, however. Tungsten can also be determined spectrophotometrically as tungsten(V) ferrocyanide. The absorbance of the brown complex is measured in aqueous solution or preferably after extraction into isoamyl alcohol. As many alloying elements interfere, they should be separated by the ferrocyanide extraction or other suitable method. Both the separation and the determination methods give satisfactory results with an overall error of not more than 0.5% in the analysis of practical samples containing low or high percentages of tungsten. (author)

  16. Electrokinetic treatment of firing ranges containing tungsten-contaminated soils.

    Science.gov (United States)

    Braida, Washington; Christodoulatos, Christos; Ogundipe, Adebayo; Dermatas, Dimitris; O'Connor, Gregory

    2007-11-19

    Tungsten-based alloys and composites are being used and new formulations are being considered for use in the manufacturing of different types of ammunition. The use of tungsten heavy alloys (WHA) in new munitions systems and tungsten composites in small caliber ammunition could potentially release substantial amounts of this element into the environment. Although tungsten is widely used in industrial and military applications, tungsten's potential environmental and health impacts have not been thoroughly addressed. This necessitates the research and development of remedial technologies to contain and/or remove tungsten from soils that may serve as a source for water contamination. The current work investigates the feasibility of using electrokinetics for the remediation of tungsten-contaminated soils in the presence of other heavy metals of concern such as Cu and Pb with aim to removing W from the soil while stabilizing in situ, Pb and Cu. PMID:17686582

  17. Grain refinement of bronze alloy by equal-channel angular pressing (ECAP) and its effect on corrosion behaviour

    OpenAIRE

    M.M. Sadawy; Ghanem, M

    2016-01-01

    The corrosion behaviour of bronze alloy prepared by equal channel angular pressing (ECAP) was investigated in 3.5 wt. % NaCl solution. Immersion corrosion tests and different electrochemical techniques were carried out. The results showed that ECAPed bronze samples exhibited higher corrosion resistance compared with the as-cast alloy and the passive current density decreased with increasing number of passes. Moreover, the morphology of alloys indicated that the corrosion damage on the surface...

  18. Characterisation of passive layers of bronze patinas (Cu-Sn alloys) in relation with the tin content of the alloy

    OpenAIRE

    Robbiola, Luc; Fiaud, C.; Harch, A.

    1993-01-01

    International audience In order to develop our knowledge of the relations between the high degree of protectiveness of passive layers and their composition, corroded archaeological bronzes of Bronze Age (1500-950 BC) have been characterised by different methods of analysis. Results reveal that the passive layers have a bilayer structure and are due to the selective dissolution of copper from the copper solid solution of the alloy to the electrolyte. For all of the objects, the ratio [(Sn/C...

  19. Microstructure and properties of liquid-phase sintered tungsten heavy alloys by using ultra-fine tungsten powders

    Institute of Scientific and Technical Information of China (English)

    于洋; 王尔德

    2004-01-01

    The microstructure and properties of liquid-phase sintered 93W-4.9Ni-2.1Fe tungsten heavy alloys using ultra-fine tungsten powders (medium particle size of 700 nm) and original tungsten powders (medium particle size of 3 μm) were investigated respectively. Commercial tungsten powders (original tungsten powders) were mechanically milled in a high-energy attritor mill for 35 h. Ultra-fine tungsten powders and commercial Ni, Fe powders were consolidated into green compacts by using CIP method and liquid-phase sintering at 1 465 ℃ for 30 min in the dissociated ammonia atmosphere. Liquid-phase sintered tungsten heavy alloys using ultra-fine tungsten powders exhibit full densification (above 99% in relative density) and higher strength and elongation compared with conventional liquidphase sintered alloys using original tungsten powders due to lower sintering temperature at 1 465 ℃ and short sintering time. The mechanical properties of sintered tungsten heavy alloy are found to be mainly dependent on the particles size of raw tungsten powders and liquid-phase sintering temperature.

  20. Degradation measurement of bronzes, a recent application of the TLA techniques in the field of cultural heritage

    International Nuclear Information System (INIS)

    The thin layer technique is normally applied in wear and corrosion monitoring of mechanical and plant components. A recent applications refers to the field of Cultural Heritage. In particular thought national and international research programmes TLA is used as a sensitivity toll in determining the properties towards corrosion of new bronze alloys to be used for artistic purposes, as in manufacturing of outdoor artworks. One activated and exposed to natural or artificial corrosive environments the bronze surface is treated with pick ling solutions to remove the corrosion products, The corresponding thickness loss is determined by the relevant γ-activity loss. The method sensitivity allows of the thickness loss evaluation in the order micrometers of lower. Besides comparative analyses of the behaviour of different bronze alloys, this method is also applied in determining the effectiveness of corrosion inhibitor or protective films, normally used on outdoor bronze sculptures. The metal activation is carried out by using a cyclotron accelerated proton beam (11.5 MeV) which products on the bronze surface and along a defined depth γemitting radionuclide 65Zn (t1/2= 244 days). In the present paper, bronze corrosion results obtained in different environmental conditions as outdoor exposures and artificial weathering experiments are reported

  1. Characterisation of Late Bronze Age large size shield nails by EDXRF, micro-EDXRF and X-ray digital radiography

    International Nuclear Information System (INIS)

    In the present study six exceptional large size metallic nails, a dagger and a sickle from the Late Bronze Age archaeological site of Figueiredo das Donas (Central Portugal) have been analysed by EDXRF, micro-EDXRF and X-ray digital radiography for the study of material composition and technology of fabrication. The combination of these analytical and examination techniques showed that all artefacts are made of bronze with As, Sb and Pb impurities, and that the nails were most likely manufactured using the casting-on technique. These results reinforce the use of binary bronze by Late Bronze Age in the region, and the incorporation of new fabrication technologies that resulted from ancient spheres of interaction. - Highlights: → EDXRF, micro-EDXRF and X-ray digital radiography in cultural heritage studies. → Archaeometallurgical study of a Late Bronze Age artefact collection from Portugal. → Practise of a specific and traditional bronze metallurgy. → Appearance of technological innovations as the casting-on technique.

  2. Formation of nanoscale tungsten oxide structures and colouration characteristics

    Indian Academy of Sciences (India)

    Vijay Bhooshan Kumar; Dambarudhar Mohanta

    2011-06-01

    In this work, pH dependent evolution of tungsten oxide (WO3) nanostructures is being reported along with physical characteristics. The synthesis was carried out via an inexpensive solvothermal cum chemical reduction route, with sodium tungstate (Na2WO4) and cetyl trimethyl ammonium bromide (C19H42NBr) as main reactants. The X-ray diffraction, together with transmission electron microscopic studies have revealed formation of regular polyhedral nanocrystalline structures and fractals as one goes from higher pH (= 5.5) to lower pH (= 2) values. The average crystallite size, as calculated throughWilliamson–Hall plots, was varied within 2.8–6.8 nm for different pH samples. Fourier transform infrared spectroscopy reveals in-plane bending vibration (W–OH), observable at ∼1630 cm-1 and strong stretching (W–O–W) located at ∼814 cm-1. Raman spectroscopy has divulged WO3 Raman active optical phonon modes positioned at ∼717 and 805 cm-1. The thermochromic and photochromic properties of the nanoscale WO3 sample prepared at pH = 5.5, are also highlighted.

  3. Hardening of self ion implanted tungsten and tungsten 5-wt% rhenium

    International Nuclear Information System (INIS)

    Highlights: ► W+ ion implantation was used to simulate neutron damage in W and W–5 wt%Re. ► A Hardness increase in pure tungsten was seen to saturate by 0.4 dpa. ► TEM of pure W shows little change in damage levels between 0.4 and 33 dpa. ► W–5 wt%Re alloy shows a hardness saturation between 0.07 dpa and 1.2 dpa. ► Above 13 dpa rhenium clusters are seen by APT and hardness rapidly increases. - Abstract: Tungsten is one of the most promising materials for high temperature components in any future nuclear fusion tokamak. In this study tungsten-ion implantation has been used to simulate the damage caused by neutrons in pure tungsten and tungsten 5 wt% rhenium. This damaged layer is only 300 nm deep so conventional mechanical tests cannot be used to investigate it. Nanoindentation has been used to measure the change in hardness as a function of six damage levels (0 dpa, 0.07 dpa, 0.4 dpa, 1.2 dpa, 13 dpa and 33 dpa). In pure tungsten the hardness increase is seen to saturate by 0.4 dpa at ≈0.8 GPa. Transmission electron microscopy of the damage structure sees a similar saturation of the loop volume number density at the same damage level. In the tungsten 5 wt% rhenium the increase in hardness is constant between 0.07 and 1.2 dpa, ≈0.85 GPa. The loop volume number density as measured using TEM is also shows little change in this region. At a damage level of 33 dpa the hardness increase is 2.88 GPa; this corresponds with the formation of small 3–5 nm rhenium clusters as observed using atom probe tomography.

  4. Wet and dry accelerated aging tests in a spray chamber to understand the effects of acid rain frequencies on bronze corrosion

    OpenAIRE

    Gianni, Liliana; Cavallini, Mauro; Natali, Stefano; Adriaens, Annemie

    2013-01-01

    We have conducted controlled laboratory experiments using a series of bronze alloys exposed to frequent, repeated wet and dry cycles, to simulate frequent acid rain exposure and study the resultant corrosion processes in bronze artifacts exposed to an outdoor urban environment. To simulate rainwater and condensation, a spray chamber for the corrosion tests was assembled, which delivered homogeneous vapor diffusion and drop deposition. Three bi-component bronzes, with 3%, 7% and 20% tin conten...

  5. Chronology for the Aegean Late Bronze Age 1700-1400 B.C.

    Science.gov (United States)

    Manning, Sturt W; Ramsey, Christopher Bronk; Kutschera, Walter; Higham, Thomas; Kromer, Bernd; Steier, Peter; Wild, Eva M

    2006-04-28

    Radiocarbon (carbon-14) data from the Aegean Bronze Age 1700-1400 B.C. show that the Santorini (Thera) eruption must have occurred in the late 17th century B.C. By using carbon-14 dates from the surrounding region, cultural phases, and Bayesian statistical analysis, we established a chronology for the initial Aegean Late Bronze Age cultural phases (Late Minoan IA, IB, and II). This chronology contrasts with conventional archaeological dates and cultural synthesis: stretching out the Late Minoan IA, IB, and II phases by approximately 100 years and requiring reassessment of standard interpretations of associations between the Egyptian and Near Eastern historical dates and phases and those in the Aegean and Cyprus in the mid-second millennium B.C. PMID:16645092

  6. The influence of modification by superdispersed powders on the lead-tin-base bronze structure

    Science.gov (United States)

    Semenkov, I. V.; Martyushev, N. V.; Popelyukh, A. I.; Alpeisov, A. T.; Drozdov, Yu Yu; Zykova, A. P.

    2016-04-01

    The paper presents data on the influence of additives of the pre-treated aluminium oxide powder on the structure of cast lead-tin-based bronzes. Different quantities of the modifier, based on the superdispersed aluminum oxide powder, were added to the bronze melt. The studies have shown that addition of a small amount of aluminum oxide powder (0.07... 0.25 %) allows modifying the micro structure of the obtained castings. This modification includes grain refinement, reduction of the matrix dendrites size of tin solid solution in copper, as well as formation of spherical inclusions of the low-melting phase - lead. In this case, the addition of such modifier influences weakly the morphology and the quantity of solid eutectoid inclusions based on electron compound Cu31 Sn8.

  7. Comparative modeling of Bronze Age land use in the Malatya Plain (Turkey)

    Science.gov (United States)

    Arıkan, Bülent; Restelli, Francesca Balossi; Masi, Alessia

    2016-03-01

    Computational modeling in archeology has proven to be a useful tool in quantifying changes in the paleoenvironment. This especially useful method combines data from diverse disciplines to answer questions focusing on the complex and non-linear aspects of human-environment interactions. The research presented here uses various proxy records to compare the changes in climate during the Bronze Age in the Malatya Plain in eastern Anatolia, which is situated at the northern extremity of northern Mesopotamia. Extensive agropastoral land use modeling was applied to three sites of different size and function in the Malatya Plain during the Early Bronze Age I period to simulate the varying scale and intensity of human impacts in relation to changes in the level of social organization, demography, and temporal length. The results suggest that even in land use types subjected to a light footprint, the scale and intensity of anthropogenic impacts change significantly in relation to the level of social organization.

  8. Multielement analysis of archaic Chinese bronze and antique coins by fast neutron activation analysis

    International Nuclear Information System (INIS)

    Samples of archaic bronze have been investigated by fast neutron activation analysis using both the absolute and relative method. The components Cu, Zn, Sn and Pb have been determined quantitatively. For the detection of lead via the short-lived isomeric state 207mPb, cyclic activation and measurement technique was used with pneumatic sample transfer between detector and central irradiation position of the neutron tube. For non-destructive analysis of antique Chinese coins the samples had to be irradiated outside the neutron generator KORONA. The activation reactions, the evaluation of the elemental concentrations and the accuracy of the results are discussed. The data were corrected for γ-ray self-absorption in the samples and summing of coincident γ-rays in the detector. According to reported typical compositions of Chinese bronze from different dynasties, the age of the samples has been derived from the results obtained. (orig.)

  9. Multielement analysis of archaic Chinese bronze and antique coins by fast neutron activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Y.H. (Academia Sinica, Lanzhou, Gansu (China). Inst. of Modern Physics); Pepelnik, R.; Fanger, H.U. (GKSS-Forschungszentrum Geesthacht GmbH, Geesthacht-Tesperhude (Germany, F.R.). Inst. fuer Physik)

    1990-01-01

    Samples of archaic bronze have been investigated by fast neutron activation analysis using both the absolute and relative method. The components Cu, Zn, Sn and Pb have been determined quantitatively. For the detection of lead via the short-lived isomeric state {sup 207m}Pb, cyclic activation and measurement technique was used with pneumatic sample transfer between detector and central irradiation position of the neutron tube. For non-destructive analysis of antique Chinese coins the samples had to be irradiated outside the neutron generator KORONA. The activation reactions, the evaluation of the elemental concentrations and the accuracy of the results are discussed. The data were corrected for {gamma}-ray self-absorption in the samples and summing of coincident {gamma}-rays in the detector. According to reported typical compositions of Chinese bronze from different dynasties, the age of the samples has been derived from the results obtained. (orig.).

  10. Connections: the relationships between Neolithic and Bronze Age Megalithic Astronomy in Britain

    CERN Document Server

    Higginbottom, Gail

    2015-01-01

    It has already been empirically verified that for many Bronze Age monuments erected in Scotland between 1400-900 BC, there was a concerted effort on behalf of the builders to align their monuments to astronomical bodies on the horizon. It has also been found that there are two common sets of complex landscape and astronomical patternings, combining specific horizon qualities, like distance and elevation, with the rising and setting points of particular astronomical phenomena. However, it has only been very recently demonstrated by us that that the visible astronomical-landscape variables found at Bronze Age sites on the inner isles and mainland of western Scotland were first established nearly two millennia earlier, with the erection of the mooted first standing-stone 'great circles' in Britain: Callanish and Stenness of Scotland (see G. Higginbottom and R. Clay, The Origins of Standing Stone Astronomy in Britain submitted to Journal of Archaeological Science & available on ArXiv). In the current paper we...

  11. Studies on bronze pre-monetary signs found in Dobroudja using XRF and micro-PIXE

    Science.gov (United States)

    Constantinescu, B.; Cristea-Stan, D.; Talmatchi, G.; Ceccato, D.

    2016-03-01

    We performed compositional analyses on 180 Scythian-type arrowheads and pre-monetary signs using XRF method and on 60 small fragments of such items (approx. 100 microns diameter), sampling being performed on previously corrosion-cleaned areas on their surface, using micro-PIXE. The items are found in Dobroudja, Istros-Histria region. The most relevant for numismatists result is that for each finding place the same type of alloy was used both for fighting arrowheads and for pre-monetary signs. Our analyses revealed three types of alloys: Cu-Sn-Pb ("normal" bronze), Cu-Sn-Mn-Pb and Cu-Sn-Sb-Pb. The presence of antimony suggests the use of fahlore-type poly-metals deposits, most probably from Caucasus Mountains. The problem of ancient bronze containing manganese is more complicated; an explanation could be the use of manganese oxides as flux necessary to smelt oxidized ores.

  12. Palaeodemographic and palaeopathological characteristics of individuals buried in three Bronze Age sites from southern Croatia

    Directory of Open Access Journals (Sweden)

    M. Novak

    2011-12-01

    Full Text Available The purpose of this study is to reconstruct paleodemographic and paleopathological characteristics of sixteen individuals (three subadults, seven males and six females buried in three Bronze Age sites (Crip, Matkovići, and Veliki Vanik located in southern Croatia. The analysed sample is characterised by the presence of pathological changes which are often associated with stressful episodes such as anaemia, inadequate nutrition, infectious diseases and the occurrence of parasites. Cribra orbitalia, dental enamel hypoplasia, porotic hyperostosis and periostitis were observed in seven out of sixteen analysed skeletons. One ulnar “parry” fracture and three fractures of the frontal bone strongly suggest the presence of deliberate interpersonal violence within the studied communities. The average life span of the adults, as well as the number and character of the observed pathologies, suggest a relatively poor life quality and harsh living conditions in the studied region during the Bronze Age.

  13. Marks of heliacal rising of Sirius on the sundial of the Bronze Age

    CERN Document Server

    Vodolazhskaya, Larisa N; Nevsky, Mikhail Yu

    2015-01-01

    The article presents the results of interdisciplinary research made with the help of archaeological, physical and astronomical methods. The aim of the study were analysis and interpretation corolla marks of the vessel of the Late Bronze Age, belonging to Srubna culture and which was found near the Staropetrovsky village in the northeast of the Donetsk region (Central Donbass). Performed calculations and measurements revealed that the marks on the corolla of Staropetrovsky vessel are marking of horizontal sundial with a sloping gnomon. Several marks on the corolla of the vessel have star shape. Astronomical calculations show that their position on the corolla, as on "dial" of watch, indicates the time of qualitative change the visibility of Sirius in the day its heliacal rising and the next few days in the Late Bronze Age at the latitude of detection of Staropetrovsky vessel. Published in the article the results of astronomical calculations allow to state that astronomical year in the Srubna tradition began wi...

  14. Radiocarbon dating of ancient bronze statues: Preliminary results from the Riace statues

    International Nuclear Information System (INIS)

    The low amount of material needed for the measurements makes AMS radiocarbon a technique suitable for the dating of ancient bronze artefacts through the analysis of the organic residues contained into the casting cores. We present the results of the AMS radiocarbon dating analyses carried out on the organic remains extracted from the casting cores of the Riace bronzes, among the most famous and well preserved sculptures of the Greek-Classical period. Although different dating hypotheses have been suggested on the base of stylistic considerations, no conclusive answers are, so far, available. The sample selection and preparation protocols of the different kind of organic materials (charred wood, vegetal remains and animal hairs) are described as well as the interpretation of the results in the frame of the current dating hypotheses and available analytical information about the casting technology.

  15. Biological affinities and adaptations of Bronze Age Bactrians: III. An initial craniometric assessment.

    Science.gov (United States)

    Hemphill, B E

    1998-07-01

    Discovery of a previously unknown Bronze Age civilization (Oxus Civilization) centered on the oases of Central Asia immediately raised questions concerning the origin and interregional impacts of this civilization. Fifteen craniometric variables from 12 Bronze Age samples--encompassing 544 adults from Central Asia, Iran, the Indus Valley, and Anatolia--are compared to test which, if any, of the current hypotheses offered by archaeologists are best supported by the pattern of phenetic affinities possessed by the Oxus Civilization inhabitants of the north Bactrian oasis. Craniometric differences between samples are compared with Mahalanobis generalized distance, and patterns of phenetic affinity are assessed with two types of cluster analysis (WPGMA, neighbor-joining method), multidimensional scaling, and principal coordinates analysis. Results obtained by this analysis indicate that current hypotheses for both the origin and interregional impacts of Oxus Civilization populations are incomplete. PMID:9696149

  16. Textile remains on a Roman bronze vessel from Řepov (Czech Republic)

    Czech Academy of Sciences Publication Activity Database

    Urbanová, K.; Březinová, Helena

    Vol. 10. Oxford : Oxbow Books, 2010 - (Andersson Strand, E.; Gleba, M.; Mannering, U.; Munkholt, C.; Ringgaard, M.), s. 242-246 ISBN 978-1-84217-370-1. - (Ancient Textile s. 5). [North European Symposium for Archaeological Textile s /10./. Copenhagen (DK), 14.05.2008-17.05.2008] Institutional research plan: CEZ:AV0Z80020508 Keywords : textile remains * corrosion products * Roman bronze vessel Subject RIV: AC - Archeology, Anthropology, Ethnology

  17. Neolithic and Bronze Age migration to Ireland and establishment of the insular Atlantic genome.

    Science.gov (United States)

    Cassidy, Lara M; Martiniano, Rui; Murphy, Eileen M; Teasdale, Matthew D; Mallory, James; Hartwell, Barrie; Bradley, Daniel G

    2016-01-12

    The Neolithic and Bronze Age transitions were profound cultural shifts catalyzed in parts of Europe by migrations, first of early farmers from the Near East and then Bronze Age herders from the Pontic Steppe. However, a decades-long, unresolved controversy is whether population change or cultural adoption occurred at the Atlantic edge, within the British Isles. We address this issue by using the first whole genome data from prehistoric Irish individuals. A Neolithic woman (3343-3020 cal BC) from a megalithic burial (10.3× coverage) possessed a genome of predominantly Near Eastern origin. She had some hunter-gatherer ancestry but belonged to a population of large effective size, suggesting a substantial influx of early farmers to the island. Three Bronze Age individuals from Rathlin Island (2026-1534 cal BC), including one high coverage (10.5×) genome, showed substantial Steppe genetic heritage indicating that the European population upheavals of the third millennium manifested all of the way from southern Siberia to the western ocean. This turnover invites the possibility of accompanying introduction of Indo-European, perhaps early Celtic, language. Irish Bronze Age haplotypic similarity is strongest within modern Irish, Scottish, and Welsh populations, and several important genetic variants that today show maximal or very high frequencies in Ireland appear at this horizon. These include those coding for lactase persistence, blue eye color, Y chromosome R1b haplotypes, and the hemochromatosis C282Y allele; to our knowledge, the first detection of a known Mendelian disease variant in prehistory. These findings together suggest the establishment of central attributes of the Irish genome 4,000 y ago. PMID:26712024

  18. Friction stir processing and fusion welding in nickel aluminum propeller bronze

    OpenAIRE

    Fuller, Michael D.

    2006-01-01

    Friction Stir Processing (FSP) is currently being developed for applications including as-cast Nickel- Aluminum Bronze (NAB). Fabrication and repair of the United States Navy's NAB propellers involve fusion welding of as-cast NAB and so it is probable that FSP is likely to encounter as deposited weld metal as well as the more slowly cooled as-cast material. Here, the microstructure and resulting distribution of mechanical properties was examined for a fusion weld overlay, an FSP stir zone an...

  19. An attempt to date an antique Benin bronze using neutron resonance capture analysis

    Energy Technology Data Exchange (ETDEWEB)

    Blaauw, M. [Interfaculty Reactor Institute, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands)]. E-mail: blaauw@iri.tudelft.nl; Postma, H. [Interfaculty Reactor Institute, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Mutti, P. [IRMM, Joint Research Centre, Retieseweg, 2440 Geel (Belgium)

    2005-03-01

    Neutron resonance capture analysis was applied to a bronze commemorative plaque from the West-African country Benin. By comparison with recently published element compositions of Benin memorial heads, the alloy of the plaque could be dated to the period 1725-1897 AD. In the analysis procedure, the object was not damaged, cleaned or altered, and very little long-lived radioactivity was induced.

  20. An attempt to date an antique Benin bronze using neutron resonance capture analysis

    International Nuclear Information System (INIS)

    Neutron resonance capture analysis was applied to a bronze commemorative plaque from the West-African country Benin. By comparison with recently published element compositions of Benin memorial heads, the alloy of the plaque could be dated to the period 1725-1897 AD. In the analysis procedure, the object was not damaged, cleaned or altered, and very little long-lived radioactivity was induced

  1. An attempt to date an antique Benin bronze using neutron resonance capture analysis.

    Science.gov (United States)

    Blaauw, M; Postma, H; Mutti, P

    2005-03-01

    Neutron resonance capture analysis was applied to a bronze commemorative plaque from the West-African country Benin. By comparison with recently published element compositions of Benin memorial heads, the alloy of the plaque could be dated to the period 1725-1897 AD. In the analysis procedure, the object was not damaged, cleaned or altered, and very little long-lived radioactivity was induced. PMID:15607919

  2. Some spatial aspects of the ritual behaviour at the beginning of Bronze Age

    Czech Academy of Sciences Publication Activity Database

    Kruťová, Magdalena; Turek, J.

    Plzeň : Čeněk, 2004 - (Šmejda, L.; Turek, J.), s. 48-56 ISBN 80-86898-07-5. [Annual Meeting of the European Association of Archaeologists /8./. Thessaloniki (GR), 24.09.2002-29.09.2002] Institutional research plan: CEZ:AV0Z8002910 Keywords : continuity * spatial relationships * cemmeteries * Bronze Age Subject RIV: AC - Archeology, Anthropology, Ethnology

  3. Altered states of consciousness and ritual in late Bronze Age Cyprus

    OpenAIRE

    Collard, David

    2011-01-01

    This thesis combines an anthropological approach to the study of Altered States of Consciousness (ASCs) with a detailed analysis of previously published evidence for the consumption of psychoactives from Late Bronze Age Cypriote (Late Cypriote) contexts to investigate the possibility that such mental phenomena may have been utilised within religious rituals of this period. This evidence primarily consists of ceramic vessels associated with the consumption of opium and alcohol (often supported...

  4. Electrochemical monitoring of nickel–aluminium bronze crevice corrosion solutions using boron–doped diamond electrode

    OpenAIRE

    Neodo, Stefano

    2013-01-01

    This study has demonstrated the capability of electrochemically assessing the metal–ion concentrations generated from the localised corrosion of nickel–aluminium bronzes (NAB). Prior to investigating NAB crevice corrosion, its electrochemical properties were studied at different pHs and chloride concentrations. At solution pHs higher than 4 NAB exhibited a corrosion behaviour similar to that of unalloyed copper and its oxidation was controlled by the dissolution of the copper–rich ?–phase. Ho...

  5. Palaeodemographic and palaeopathological characteristics of individuals buried in three Bronze Age sites from southern Croatia

    OpenAIRE

    Novak, M; V. Vyroubal; Ž. Bedić

    2011-01-01

    The purpose of this study is to reconstruct paleodemographic and paleopathological characteristics of sixteen individuals (three subadults, seven males and six females) buried in three Bronze Age sites (Crip, Matkovići, and Veliki Vanik) located in southern Croatia. The analysed sample is characterised by the presence of pathological changes which are often associated with stressful episodes such as anaemia, inadequate nutrition, infectious diseases and the occurrence of parasites. Cribra or...

  6. New insight into the nature and properties of pale green surfaces of outdoor bronze monuments

    Science.gov (United States)

    Robbiola, L.; Rahmouni, K.; Chiavari, C.; Martini, C.; Prandstraller, D.; Texier, A.; Takenouti, H.; Vermaut, P.

    2008-07-01

    The present study concerns the chemical physical and electrochemical characterisations of the pale green surfaces formed on outdoor bronzes exposed in urban conditions. In the first part, results from investigations performed on the equestrian statue of the French king Louis XIV exposed in the Palace of Versailles (France) are given. Analyses by energy-dispersive spectrometry and Raman spectroscopy, coupled with scanning electron microscopy, show that the external layer is characterised by a marked selective dissolution of copper and zinc of the alloy leading to an important relative enrichment in tin compounds. The same phenomenon with the same magnitude, determined from dissolution factors fCu and fZn, has also been evidenced on other bronze monuments used for comparison. Proportionality between the amount of dissolved copper and zinc cations to their respective initial content in the alloy is evidenced independently of the tin content. The pale green patina appears to be a complex mixture of copper and tin compounds whose structure still needs to be more precisely characterised. In the second part, the electrochemical reactivity of tin compound enriched patina was investigated by cyclic voltammetry from a Cu10Sn electrode in sulfate solution at pH=2 and 5.6. This patina is stable at pH 5.6 but reactive at pH 2 in relation to the modification of properties of tin species in the patina. Mott Schottky application in pH 5.6 solution revealed that the bronze patina exhibits two types of semiconducting properties according to the potential domains, similar to what has been observed for pure tin in aqueous solutions. The destabilisation of bronze patinas in outdoor conditions and consequently the cyclic erosion due to rainfall have been attributed to the modification of tin species properties rather than to the transformation of copper compounds.

  7. On the Origin of Bronze Belt Plaques of Ancient Nomads in Northern China

    Institute of Scientific and Technical Information of China (English)

    WUEn; 丁小雷

    2003-01-01

    The bronze plaques decorated with animal, human or geometric designs were the ornaments on the leather belts of the nomadic people, such as Xiongnu (Hun) and Xianbei (Sienpi) in Northern China in the Qin and Han Dynasties. These plaques had unique regional and ethnical characteristics. There have been many different ideas on the origination of this kind of plaques. The author plans to give his own opinion hereby on this issue.

  8. Connections: the relationships between Neolithic and Bronze Age Megalithic Astronomy in Britain

    OpenAIRE

    Higginbottom, Gail; Clay, Roger

    2015-01-01

    It has already been empirically verified that for many Bronze Age monuments erected in Scotland between 1400-900 BC, there was a concerted effort on behalf of the builders to align their monuments to astronomical bodies on the horizon. It has also been found that there are two common sets of complex landscape and astronomical patternings, combining specific horizon qualities, like distance and elevation, with the rising and setting points of particular astronomical phenomena. However, it has ...

  9. Towards mineralogical and geochemical reference groups for some Bronze Age ceramics 
from Transylvania (Romania)

    OpenAIRE

    Volker Hoeck; Corina Ionescu; Lucretia Ghergari; Carmen Precup

    2009-01-01

    Based on their chemical composition ceramic shards from three Bronze Age sites in Transylvania, i.e., Copăceni, Derşida and Palatca respectively, were distinguished by major, trace, and RE elements. Within the Copăceni samples, two subgroups (A and B) showing different chemistry and mineralogy were additionally separated out. The link between chemistry and mineralogy showed clearly the important contribution of the temper to the overall chemistry of the ceramic shards. In turn, the chemistry ...

  10. 黑豆嘴类型青铜器中的西来因素%Western Elements in the Bronzes of Heidouzui Type

    Institute of Scientific and Technical Information of China (English)

    张文立; 林沄

    2004-01-01

    The cultural elements contained in the bronzes of Heidouzui type have often been studied in academic circles,but no unanimous views have been reached.The present paper discusses two forms of bronze ornaments of the Kayao culture in the Qinghai region and their date,as well as the relationship of some bronzes handed down from ancient times with those unearthed from Qinghai.On the basis of their comparative study the authors put forward that the Heidouzui-type bronzes contain cultural elements coming from the Qinghai region and even farther areas.These western elements might have been spread eastward and northward to still farther regions.

  11. Radioactive sodium processing apparatus

    International Nuclear Information System (INIS)

    Purpose: To enable safety, continuous and economical disposal for radioactive sodium while preventing radioactive contaminations. Constitution: Reaction gas introduction pipe for introducing oxygen and carbon dioxygen, and steams for accelerating the processing speed, as well as a discharge pipe for sodium carbonate as reaction products are connected to the lower side wall of a radioactive sodium processing container. A screw conveyor is mounted within the radioactive sodium processing container and a torque meter is disposed in the central axis of the conveyor. Signals from the torque meter are sent to an oxygen introduction control device. V-shaped recesses are formed to the screw blades of the conveyor for improving the separating efficiency between sodium carbonate produced through the procession and not-processed radioactive sodium. Since sodium is converted after the process into sodium carbonate, it can be handled and stored within ease. (Yoshihara, H.)

  12. Sodium Ferric Gluconate Injection

    Science.gov (United States)

    Sodium ferric gluconate injection is used to treat iron-deficiency anemia (a lower than normal number of ... are also receiving the medication epoetin (Epogen, Procrit). Sodium ferric gluconate injection is in a class of ...

  13. Docusate Sodium and Pregnancy

    Science.gov (United States)

    ... live chat Live Help Fact Sheets Share Docusate Sodium Friday, 01 April 2016 In every pregnancy, a ... This sheet talks about whether exposure to docusate sodium may increase the risk for birth defects over ...

  14. Diclofenac sodium overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002630.htm Diclofenac sodium overdose To use the sharing features on this page, please enable JavaScript. Diclofenac sodium is a prescription medicine used to relieve pain ...

  15. Sodium carbonate poisoning

    Science.gov (United States)

    Sodium carbonate (known as washing soda or soda ash) is a chemical found in many household and ... products. This article focuses on poisoning due to sodium carbonate. This article is for information only. Do ...

  16. Sodium hydroxide poisoning

    Science.gov (United States)

    Sodium hydroxide is a very strong chemical. It is also known as lye and caustic soda. This ... poisoning from touching, breathing in (inhaling), or swallowing sodium hydroxide. This article is for information only. Do ...

  17. Naproxen sodium overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002507.htm Naproxen sodium overdose To use the sharing features on this page, please enable JavaScript. Naproxen sodium is a nonsteroidal anti-inflammatory drug (NSAID) used ...

  18. Processing parameter optimization for the laser dressing of bronze-bonded diamond wheels

    Science.gov (United States)

    Deng, H.; Chen, G. Y.; Zhou, C.; Li, S. C.; Zhang, M. J.

    2014-01-01

    In this paper, a pulsed fiber-laser dressing method for bronze-bonded diamond wheels was studied systematically and comprehensively. The mechanisms for the laser dressing of bronze-bonded diamond wheels were theoretically analyzed, and the key processing parameters that determine the results of laser dressing, including the laser power density, pulse overlap ratio, ablation track line overlap ratio, and number of scanning cycles, were proposed for the first time. Further, the effects of these four key parameters on the oxidation-damaged layer of the material surface, the material removal efficiency, the material surface roughness, and the average protrusion height of the diamond grains were explored and summarized through pulsed laser ablation experiments. Under the current experimental conditions, the ideal values of the laser power density, pulse overlap ratio, ablation track line overlap ratio, and number of scanning cycles were determined to be 4.2 × 107 W/cm2, 30%, 30%, and 16, respectively. Pulsed laser dressing experiments were conducted on bronze-bonded diamond wheels using the optimized processing parameters; next, both the normal and tangential grinding forces produced by the dressed grinding wheel were measured while grinding alumina ceramic materials. The results revealed that the normal and tangential grinding forces produced by the laser-dressed grinding wheel during grinding were smaller than those of grinding wheels dressed using the conventional mechanical method, indicating that the pulsed laser dressing technology provides irreplaceable advantages relative to the conventional mechanical dressing method.

  19. Evaluation of the inhibitive effect of benzotriazole on archeological bronze in acidic medium

    Science.gov (United States)

    Hassairi, Hèla; Bousselmi, Latifa; Khosrof, Slim; Triki, Ezzeddine

    2013-12-01

    An archaeological bronze artefact was a Punic coin excavated from the north east of Tunisia in 2001. The composition of the copper alloy revealed a content of 3.5 % of tin and 1.4 % of lead with the presence of some sulphur heterogeneity. The surface presents some roughnesses and cracks and is covered by a corrosion layer of 20-40 μm thickness. The use of benzotriazole (BTA) as an inhibitor has become a standard element for the preservation of cuprous-based metals. In order to investigate the behaviour of BTA in an acidic medium, an Electrochemical Impedance Spectroscopy (EIS) investigation was performed to characterize the electrochemical behaviour of the interface of the archaeological bronze sample/acidic medium without and with BTA addition. Impedance diagrams obtained at different immersion times show that the presence of the inhibitor prevents the diffusional process observed in the absence of BTA. The inhibition of the pre-polarized bronze surface revealed that the mechanism of action of the benzotriazole molecule in an acidic medium is governed by the chemisorption process.

  20. Effect of heat treatment on microstructure and properties of hot-extruded nickel-aluminum bronze

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The effect of heat treatment on the microstructure and properties of a hot-extruded nickel-aluminum bronze was investigated. Experimental materials were heat treated through different processes, including quenching, normalizing, aging and annealing, and their microstructure, corrosion resistance and mechanical properties were characterized. It is found that quenching causes all β phase transformed into β' phase, however, normalizing causes β phase transformed into β', α and κ phases. When the quenched sample is aged, fine κ phase is precipitated from the as-quenched microstructure of β' phase. Annealing causes the transformation of β' into a and κ phases. The results of mechanical property tests show that quenching, normalizing and aging improve the tensile strength and hardness of the experimental material, with a corresponding fall in elongation. Annealing raises the elongation but reduces the tensile strength and hardness. Furthermore, corrosion resistance of nickel-aluminum bronze ranks from worse to better in the following order: aged, quenched, normalized, hot-extruded and annealed. However, with the exposure time of corrosion test increasing, the difference of average corrosion rate between those nickel-aluminum bronzes tums small.

  1. Properties and performance of fine-filament bronze-process Nb3Sn conductors

    Science.gov (United States)

    Walker, M. S.; Cutro, J. M.; Zeitlin, B. A.; Ozeryansky, G. M.; Schwall, R. E.; Oberly, C. E.; Ho, J. C.; Woollam, J. A.

    1979-01-01

    Fine-filament bronze-process Nb3Sn superconductors were fabricated to fulfill stringent requirements on critical current under tension in a one-inch bend diameter, current density, stability, and conductor losses. A large fraction of niobium filaments was incorporated in a bronze matrix, and a cable containing 4453 2-micron diameter filaments in each of six strands provided a current density of 85,000 A/sq cm at 10 to the -11th ohm-cm, 10 T, and 4.2 K. The next step was to incorporate copper stabilizer in a conductor with 20,538 filaments. These conductors, fabricated so that bend strains of about 1% would be experienced by the filaments in the one-inch bend, stably carried currents in the 200-500 A range. A quench current of 540 A in a 5-cm bend corresponds to 158,000 A/sq cm in the bronze and filament area, believed to be the highest critical current density reported for multifilamentary Nb3Sn.

  2. Band structure of the quasi two-dimensional purple molybdenum bronze

    Science.gov (United States)

    Guyot, H.; Balaska, H.; Perrier, P.; Marcus, J.

    2006-09-01

    The molybdenum purple bronze KMo 6O 17 is quasi two-dimensional (2D) metallic oxide that shows a Peierls transition towards a metallic charge density wave state. Since this specific transition is directly related to the electron properties of the normal state, we have investigated the electronic structure of this bronze at room temperature. The shape of the Mo K1s absorption edge reveals the presence of distorted MoO 6 octahedra in the crystallographic structure. Photoemission experiments evidence a large conduction band, with a bandwidth of 800 meV and confirm the metallic character of this bronze. A wide depleted zone separates the conduction band from the valence band that exhibits a fourfold structure, directly connected to the octahedral symmetry of the Mo sites. The band structure is determined by ARUPS in two main directions of the (0 0 1) Brillouin zone. It exhibits some unpredicted features but corroborates the earlier theoretical band structure and Fermi surface. It confirms the hidden one-dimensionality of KMo 6O 17 that has been proposed to explain the origin of the Peierls transition in this 2D compound.

  3. Dynamic behavior of novel tungsten penetrator materials

    International Nuclear Information System (INIS)

    The scope of the investigations was to find criteria which are related to the terminal ballistic performance of high strength tungsten KE-penetrator materials. The study comprised three tungsten alloys having densities above 17.1 g/cm3 and comparable static material strengths. For this purpose the authors investigated the dynamic material behavior by means of the instrumented Taylor-test. The influence of the strain rate on the yield strength and the maximum strain when cracking occurred were determined. The measured dynamic strength data were compared with the terminal ballistic efficiency of rods penetrating a semi-infinite RHA-target. Furthermore, the structural properties of the alloys were discussed with respect to their behavior in the regime of hydrodynamic flow

  4. Femtosecond fiber laser additive manufacturing of tungsten

    Science.gov (United States)

    Bai, Shuang; Liu, Jian; Yang, Pei; Zhai, Meiyu; Huang, Huan; Yang, Lih-Mei

    2016-04-01

    Additive manufacturing (AM) is promising to produce complex shaped components, including metals and alloys, to meet requirements from different industries such as aerospace, defense and biomedicines. Current laser AM uses CW lasers and very few publications have been reported for using pulsed lasers (esp. ultrafast lasers). In this paper, additive manufacturing of Tungsten materials is investigated by using femtosecond (fs) fiber lasers. Various processing conditions are studied, which leads to desired characteristics in terms of morphology, porosity, hardness, microstructural and mechanical properties of the processed components. Fully dense Tungsten part with refined grain and increased hardness was obtained and compared with parts made with different pulse widths and CW laser. The results are evidenced that the fs laser based AM provides more dimensions to modify mechanical properties with controlled heating, rapid melting and cooling rates compared with a CW or long pulsed laser. This can greatly benefit to the make of complicated structures and materials that could not be achieved before.

  5. Thermal stability of warm-rolled tungsten

    DEFF Research Database (Denmark)

    Alfonso Lopez, Angel

    recrystallization occur in tungsten, and quantifying the kinetics and microstructuralaspects of these restoration processes. Two warm-rolled tungsten plates are annealed attemperatures between 1100 °C and 1350 °C, under vacuum conditions or argon atmosphere. Theeffects of annealing on the microstructure are...... recoverykinetics, and recrystallization fitted to JMAK recrystallization kinetics, which in turn allowed thecalculation of recrystallization activation energies. Much faster recovery and recrystallizationkinetics were found for the plate warm-rolled to 90% thickness reduction, as compared to the platewarm......-rolled to 67% thickness reduction. An initial incubation time before recrystallization wasfound for both plates warm-rolled to 67% and 90% thickness reductions. The different Avramiexponents found for the two plates were explained microstructurally in terms of nucleation. The microstructural evolution...

  6. Microstructural evolution of tungsten oxide thin films

    Science.gov (United States)

    Hembram, K. P. S. S.; Thomas, Rajesh; Rao, G. Mohan

    2009-10-01

    Tungsten oxide thin films are of great interest due to their promising applications in various optoelectronic thin film devices. We have investigated the microstructural evolution of tungsten oxide thin films grown by DC magnetron sputtering on silicon substrate. The structural characterization and surface morphology were carried out using X-ray diffraction and Scanning Electron Microscopy (SEM). The as deposited films were amorphous, where as, the films annealed above 400 °C were crystalline. In order to explain the microstructural changes due to annealing, we have proposed a "instability wheel" model for the evolution of the microstructure. This model explains the transformation of mater into various geometries within them selves, followed by external perturbation.

  7. Microstructural evolution of tungsten oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hembram, K.P.S.S., E-mail: hembram@isu.iisc.ernet.in [Department of Instrumentation, Indian Institute of Science, Bangalore - 560 012 (India); Theoretical Science Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore - 560064 (India); Thomas, Rajesh; Rao, G. Mohan [Department of Instrumentation, Indian Institute of Science, Bangalore - 560 012 (India)

    2009-10-30

    Tungsten oxide thin films are of great interest due to their promising applications in various optoelectronic thin film devices. We have investigated the microstructural evolution of tungsten oxide thin films grown by DC magnetron sputtering on silicon substrate. The structural characterization and surface morphology were carried out using X-ray diffraction and Scanning Electron Microscopy (SEM). The as deposited films were amorphous, where as, the films annealed above 400 deg. were crystalline. In order to explain the microstructural changes due to annealing, we have proposed a 'instability wheel' model for the evolution of the microstructure. This model explains the transformation of mater into various geometries within them selves, followed by external perturbation.

  8. Enhancing the adhesion of diamond films on cobalt-cemented tungsten carbide substrate using tungsten particles via MPCVD system

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Wen Chi [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Wu, Yu-Shiang, E-mail: yswu@cc.cust.edu.tw [Department of Mechanical Engineering, China University of Science and Technology, 245, Sec. 3, Yen-Chiu-Yuan Road, Nankang, Taipei 11581, Taiwan (China); Chang, Hou-Cheng [Department of Electronic Engineering, China University of Science and Technology, Taipei 11581, Taiwan (China); Lee, Yuan-Haun [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

    2011-03-24

    Graphical abstract: Display Omitted Research highlights: > Larger particles of tungsten led to larger diamond particles with improved crystallinity, covering the specimen with increased speed. > Adhesion was indicated to be a function of the gaps between the tungsten particles. > Diamond films pretreated with tungsten particles of 2.0 {mu}m showed the highest hardness of 27.78 GPa with good crystalline. - Abstract: To increase the adhesion of diamond films and avoid the negative effects of using cobalt, previous treatments have employed tungsten particles to cover the surface of the 6 wt.% cobalt-cemented tungsten carbide (WC-Co) substrate. The surface of the tungsten particles is transformed into W{sub 2}C and WC, which attracts and traps carbon. Through the process of nucleation, the carbon forms around the tungsten particles, thereby satisfying the conditions necessary for the formation of diamond film. Using Raman spectroscopy, we determined that diamond films of good quality with excellent adhesive properties and a hardness level as high as 27.78 GPa could be produced following pretreatment with 2.0 {mu}m tungsten particles. Rockwell indentation tests indicate that addition of tungsten particles promotes the interfacial adhesion of diamond films with WC-Co substrates. We determined that using smaller tungsten particles decreased the number of gaps and cavities on the surface of the substrate, thereby enhancing the adhesion of the diamond film.

  9. A systematic approach to Bronze corrosion products and the methods of treatment , applied on three bronze anklets from Dhamar museum , Yemen

    Directory of Open Access Journals (Sweden)

    Hazem Mohamed

    2014-04-01

    Full Text Available Three bronze anklets were found during the archaeological excavation of Yemeni mission 2002 A.D, in Gabal al- lawd , Jawf area , Yemen , they dated back to Minaean period in Yemen [sixth century B.C – 24 B.C] , and now they are situated in Dhamar regional museum .They were suffered from the deterioration aspects , two of these anklets had a thick corrosion products of pale green / brown , the third anklet had a rust-colored Black and Brown with the presence of small parts and scattered pale green. The aim of this paper is to examine, in detail, the corrosion of the selected objects that was grown during the long-term burial and identify its products that will help us to understand the corrosive factors and the degradation mechanisms , as well as their constituting metals in order to carry out scientific treatment and conservation .For this purpose ,samples from the objects were examined by Metallographic Microscope (ME , Scanning Electron Microscope (SEM, the corrosion products were analyzed by X-ray diffraction (XRD and X-ray fluorescence( XRF was used to determine the objects metallic constituents . XRD data showed that the corrosion products constitute of cuprite , atacamite , and paratacamite , whereas XRF analysis declared that the anklets compose of bronze alloy . Microscopic examination reveals that the three anklets were suffered from the deterioration spots , which dispersed on the metal surface . Chemical cleaning was chosen for treating the objects , finally they were isolated to preserve them against further attack.

  10. Lithium Phosphate Glasses stabilized with Tungsten Oxide

    Czech Academy of Sciences Publication Activity Database

    Míka, M.; Mladonický, P.; Vondrák, Jiří; Stopka, Pavel; Klápště, Břetislav

    Brno: University of Technology Brno, 2002, s. 50-1-50-4. ISBN 80-214-2082-0. [Advanced Batteries and Accumulators /3./. Brno (CZ), 16.06.2002-20.06.2002] R&D Projects: GA AV ČR IAA4032002; GA ČR GA104/02/0731 Institutional research plan: CEZ:AV0Z4032918 Keywords : lithium phosphate * glass * tungsten oxide Subject RIV: CA - Inorganic Chemistry

  11. Synthesis of molybdenum and tungsten oxytetrafluorides

    Energy Technology Data Exchange (ETDEWEB)

    Butskij, V.D.; Ignatov, M.E.; Golovanov, B.V. (AN SSSR, Moscow. Inst. Obshchej i Neorganicheskoj Khimii)

    1985-03-01

    A simple method of preparating molybdenum and tungsten oxytetrafluorides by silicon dioxide interaction with hexafluoride of the corresponding metal in a glass at 120-150 deg C and MF/sub 6/ pressure of 0.4-0.5 atm, is developed. MOF/sub 4/ (M=Mo, W) yield is 94-95%, purity is 99%. Synthesized MOF/sub 4/ are characterized by the data of chemical analysis, IR and NMR/sup 19/F spectrometry.

  12. Synthesis of molybdenum and tungsten oxytetrafluorides

    International Nuclear Information System (INIS)

    A simple method of preparating molybdenum and tungsten oxytetrafluorides by silicon dioxide interaction with hexafluoride of the corresponding metal in a glass at 120-150 deg C and MF6 pressure of 0.4-0.5 atm, is developed. MOF4 (M=Mo, W) yield is 94-95%, purity is 99%. Synthesized MOF4 are characterized by the data of chemical analysis, IR and NMR19F spectrometry

  13. WO3 nano-ribbons: their phase transformation from tungstite (WO3·H2O) to tungsten oxide (WO3)

    DEFF Research Database (Denmark)

    Ahmadi, Majid; Sahoo, Satyaprakash; Younesi, Reza;

    2014-01-01

    Tungsten oxide (WO3) nano-ribbons (NRs) were obtained by annealing tungstite (WO3·H2O) NRs. The latter was synthesized below room temperature using a simple, environmentally benign, and low cost aging treatment of precursors made by adding hydrochloric acid to diluted sodium tungstate solutions (...

  14. Sodium and potassium

    International Nuclear Information System (INIS)

    Present article is devoted to sodium and potassium content in fluoride. In order to obtain the comprehensive view on sodium and potassium distribution in fluorite 892 mono mineral samples of various geologic deposits and ores of Kazakhstan, Uzbekistan, Tajikistan were analyzed. The content of sodium and potassium in fluorite of geologic deposits of various mineralogical and genetic type was defined.

  15. SODIUM ENVIRONMENTS IN GLASS

    OpenAIRE

    Greaves, G.

    1981-01-01

    Sodium environments have been measured directly in several oxide glasses using EXAFS at the sodium K edge. The existence of local structure around sodium in glass contradicts the conventional Zachariasen model. Analysis of the EXAFS indicates there are significant differences relating to the glass modifier : glass former chemistry - the details of which demonstrate similarities with crystalline silicates and borates.

  16. The tungsten divertor experiment at ASDEX Upgrade

    Science.gov (United States)

    Neu, R.; Asmussen, K.; Krieger, K.; Thoma, A.; Bosch, H.-S.; Deschka, S.; Dux, R.; Engelhardt, W.; García-Rosales, C.; Gruber, O.; Herrmann, A.; Kallenbach, A.; Kaufmann, M.; Mertens, V.; Ryter, F.; Rohde, V.; Roth, J.; Sokoll, M.; Stäbler, A.; Suttrop, W.; Weinlich, M.; Zohm, H.; Alexander, M.; Becker, G.; Behler, K.; Behringer, K.; Behrisch, R.; Bergmann, A.; Bessenrodt-Weberpals, M.; Brambilla, M.; Brinkschulte, H.; Büchl, K.; Carlson, A.; Chodura, R.; Coster, D.; Cupido, L.; de Blank, H. J.; de Peña Hempel, S.; Drube, R.; Fahrbach, H.-U.; Feist, J.-H.; Feneberg, W.; Fiedler, S.; Franzen, P.; Fuchs, J. C.; Fußmann, G.; Gafert, J.; Gehre, O.; Gernhardt, J.; Haas, G.; Herppich, G.; Herrmann, W.; Hirsch, S.; Hoek, M.; Hoenen, F.; Hofmeister, F.; Hohenöcker, H.; Jacobi, D.; Junker, W.; Kardaun, O.; Kass, T.; Kollotzek, H.; Köppendörfer, W.; Kurzan, B.; Lackner, K.; Lang, P. T.; Lang, R. S.; Laux, M.; Lengyel, L. L.; Leuterer, F.; Manso, M. E.; Maraschek, M.; Mast, K.-F.; McCarthy, P.; Meisel, D.; Merkel, R.; Müller, H. W.; Münich, M.; Murmann, H.; Napiontek, B.; Neu, G.; Neuhauser, J.; Niethammer, M.; Noterdaeme, J.-M.; Pasch, E.; Pautasso, G.; Peeters, A. G.; Pereverzev, G.; Pitcher, C. S.; Poschenrieder, W.; Raupp, G.; Reinmüller, K.; Riedl, R.; Röhr, H.; Salzmann, H.; Sandmann, W.; Schilling, H.-B.; Schlögl, D.; Schneider, H.; Schneider, R.; Schneider, W.; Schramm, G.; Schweinzer, J.; Scott, B. D.; Seidel, U.; Serra, F.; Speth, E.; Silva, A.; Steuer, K.-H.; Stober, J.; Streibl, B.; Treutterer, W.; Troppmann, M.; Tsois, N.; Ulrich, M.; Varela, P.; Verbeek, H.; Verplancke, Ph; Vollmer, O.; Wedler, H.; Wenzel, U.; Wesner, F.; Wolf, R.; Wunderlich, R.; Zasche, D.; Zehetbauer, T.; Zehrfeld, H.-P.

    1996-12-01

    Tungsten-coated tiles, manufactured by plasma spray on graphite, were mounted in the divertor of the ASDEX Upgrade tokamak and cover almost 90% of the surface facing the plasma in the strike zone. Over 600 plasma discharges have been performed to date, around 300 of which were auxiliary heated with heating powers up to 10 MW. The production of tungsten in the divertor was monitored by a W I line at 400.8 nm. In the plasma centre an array of spectral lines at 5 nm emitted by ionization states around W XXX was measured. From the intensity of these lines the W content was derived. Under normal discharge conditions W-concentrations around 0741-3335/38/12A/013/img12 or even lower were found. The influence on the main plasma parameters was found to be negligible. The maximum concentrations observed decrease with increasing heating power. In several low power discharges accumulation of tungsten occurred and the temperature profile was flattened. The concentrations of the intrinsic impurities carbon and oxygen were comparable to the discharges with the graphite divertor. Furthermore, the density and the 0741-3335/38/12A/013/img13 limits remained unchanged and no negative influence on the energy confinement or on the H-mode threshold was found. Discharges with neon radiative cooling showed the same behaviour as in the graphite divertor case.

  17. Green synthesis of tungsten trioxide monohydrate nanosheets as gas sensor

    International Nuclear Information System (INIS)

    Research highlights: → Tungsten trioxide hydrate nanosheets were synthesized using a simple sonochemical method. → The formation of nanosheets is closely related to their intrinsic crystalline structure. → The nanosheets exhibited favourable room-temperature gas-sensing performances. - Abstract: In this paper, orthorhombic tungsten trioxide monohydrate nanosheets in high yields were successfully generated using a very simple sonochemical method with tungsten hexachloride as the precursor and distilled water as the solvent. The tungsten trioxide monohydrate nanosheets exhibited thickness of about tens of nanometers and edge length of up to several hundreds of nanometers. The sheet-like morphology has been well explained based on the acoustic cavitation effect as well as the crystalline structure of orthorhombic tungsten trioxide monohydrate. The tungsten trioxide monohydrate nanosheets sensor exhibited ideal room-temperature gas-sensing performances, and were found to be sensitive to various flammable organic vapors and harmful gases. The corresponding sensing mechanisms were also discussed.

  18. Process for separation of tungsten and molybdenum by extraction

    International Nuclear Information System (INIS)

    A process for the separation of tungsten and molybdenum by extraction involves the addition of HCl or HNO3 to an aqueous solution containing tungsten and molybdenum to obtain a pH from 0.5 to 4.3, and introduction of a stabilizer comprising water-soluble phosphorus salts and a complexing agent, hydrogen peroxide, in an amount from 1.5 to 2 mole per 1 g-atom of the total content of tungsten and molybdenum. Then molybdenum is selectively extracted from the resulting aqueous solution with tri-n-butylphosphate with equal volumetric proportioning of the aqueous and organic solutions. Re-extraction of molybdenum and partially tungsten is carried out from the organic extracting agent with an alkali or soda solution. The process makes possible the preparation of tungsten solution containing no more than 0.001 g/l of molybdenum, and an increase in the degree of extraction of tungsten and molybdenum

  19. Epitaxial growth of tungsten nanoparticles on alumina and spinel surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Suarez, T; Lopez-Esteban, S; Pecharroman, C; Esteban-Cubillo, A; Moya, J S [Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Cientificas (CSIC), C/ Sor Juana Ines de la Cruz 3, 28049, Cantoblanco, Madrid (Spain); Diaz, L A; Torrecillas, R [Nanomaterials and Nanotechnology Research Center (CINN), Consejo Superior de Investigaciones CientIficas (CSIC), C/ Francisco Pintado Fe 26, 33011, Oviedo, Asturias (Spain); Gremillard, L [Universite de Lyon, INSA-Lyon, MATEIS, UMR CNRS 5510, 20 avenue Albert Einstein, Villeurbanne F-69621 (France)], E-mail: jsmoya@icmm.csic.es

    2008-05-28

    Isolated tungsten nanoparticles ({alpha}-W and {beta}-W phase) were synthesized and epitaxially grown on alumina and spinel particle surfaces with an average tungsten size of {<=}20 nm for a low tungsten content (of {<=}1.5 vol%). Using tungsten (VI) ethoxide alcoholic solutions, tungsten trioxide hydrated precursors were attached to a ceramic grains surface as a nanoparticle coating. High-resolution transmission electron microscopy (HRTEM) micrographs showed epitaxial interfaces between alumina, spinel and metallic tungsten. This epitaxial growth is assumed to be due to the effect of water vapour on the sublimation of ortho-tungstic acid during the reduction process in a hydrogen atmosphere. The planes involved in the epitaxy were found to be (22-bar 0){sub Al2O3} parallel (121){sub W} and (311){sub MgAl2O4} parallel (110){sub W}.

  20. The tungsten powder study of the dispenser cathode

    International Nuclear Information System (INIS)

    The intercorrelation of tungsten powder properties, such as grain size, distribution and morphology, and porous matrix parameters with electron emission capability and longevity of Ba dispenser cathodes has been investigated for the different grain morphologies. It is shown that a fully cleaning step of the tungsten powder is so necessary that the tungsten powder will be reduction of oxide in hydrogen atmosphere above 700 deg. C. The porosity of the tungsten matrix distributes more even and the closed pore is fewer, the average granule size of the tungsten powder distributes more convergent. The porosity of the tungsten matrix and the evaporation of the activator are bigger and the pulse of the cathode is smaller when the granularity is bigger by the analysis of the electronic microscope and diode experiment

  1. The tungsten powder study of the dispenser cathode

    Science.gov (United States)

    Bao, Ji-xiu; Wan, Bao-fei

    2006-06-01

    The intercorrelation of tungsten powder properties, such as grain size, distribution and morphology, and porous matrix parameters with electron emission capability and longevity of Ba dispenser cathodes has been investigated for the different grain morphologies. It is shown that a fully cleaning step of the tungsten powder is so necessary that the tungsten powder will be reduction of oxide in hydrogen atmosphere above 700 °C. The porosity of the tungsten matrix distributes more even and the closed pore is fewer, the average granule size of the tungsten powder distributes more convergent. The porosity of the tungsten matrix and the evaporation of the activator are bigger and the pulse of the cathode is smaller when the granularity is bigger by the analysis of the electronic microscope and diode experiment.

  2. Synthesis and electrical characterization of tungsten oxide nanowires

    Institute of Scientific and Technical Information of China (English)

    Huang Rui; Zhu Jing; Yu Rong

    2009-01-01

    Tungsten oxide nanowires of diameters ranging from 7 to 200 nm are prepared on a tungsten rod substrate by using the chemical vapour deposition (CVD) method with vapour-solid (VS) mechanism. Tin powders are used to control oxygen concentration in the furnace, thereby assisting the growth of the tungsten oxide nanowires. The grown tungsten oxide nanowires are determined to be of crystalline W18O49. Ⅰ-Ⅴ curves are measured by an in situ transmission electron microscope (TEM) to investigate the electrical properties of the nanowires. All of the Ⅰ-Ⅴ curves observed are symmetric, which reveals that the tungsten oxide nanowires are semiconducting. Quantitative analyses of the experimental I V curves by using a metal-semiconductor-metal (MSM) model give some intrinsic parameters of the tungsten oxide nanowires, such as the carrier concentration, the carrier mobility and the conductivity.

  3. Separation and estimation of tungsten and copper in tungsten-copper alloy

    International Nuclear Information System (INIS)

    The tungsten-copper alloy, also called as collet material, is regularly used in resistance welding of end caps of nuclear fuel pins during their fabrication at Nuclear Fuel Complex (NFC). The desirable properties of this material for welding purpose varies with the composition of the alloy. Therefore, it is mandatory to know its composition prior to its application. The present paper describes a modified gravimetric method where tungsten is separated from copper by digestion of the sample in concentrated nitric acid followed by filtration and subsequent ignition of the residue to tungstic oxide (WO3) while copper in the filtrate is estimated by electro-gravimetric method. A co-efficient of variation (CV) of ± 0.2% for tungsten and ± 0.4% for copper have been achieved. (author)

  4. Chemical vapour deposition of tungsten and tungsten silicide layers for applications in novel silicon technology

    CERN Document Server

    Li, F X

    2002-01-01

    This work was a detailed investigation into the Chemical Vapour Deposition (CVD) of tungsten and tungsten silicide for potential applications in integrated circuit (IC) and other microelectronic devices. These materials may find novel applications in contact schemes for transistors in advanced ICs, buried high conductivity layers in novel Silicon-On-Insulator (SOI) technology and in power electronic devices. The CVD techniques developed may also be used for metal coating of recessed or enclosed features which may occur in novel electronic or electromechanical devices. CVD of tungsten was investigated using the silicon reduction reaction of WF sub 6. W layers with an optimum self-limiting thickness of 100 nm and resistivity 20 mu OMEGA centre dot cm were produced self-aligned to silicon. A hydrogen passivation technique was developed as part of the wafer pre-clean schedule and proved essential in achieving optimum layer thickness. Layers produced by this approach are ideal for intimate contact to shallow junct...

  5. Metal-insulator transition of naxwo3 studied by angle-resolved photoemission spectroscopy

    OpenAIRE

    Raj, Satyabrata; Sato, Takafumi; Souma, Seigo; Takahashi, Takashi; Sarma, DD; Mahadevan, Priya

    2009-01-01

    The electronic structure of sodium tungsten bronzes NaxWO3 is investigated by high-resolution angle-resolved photoemission spectroscopy (ARPES). The ARPES spectra measured in both insulating and metallic phases of NaxWO3 reveals the origin of metal-insulator transition (MIT) in sodium tungsten bronze system. It is found that in insulating NaxWO3 the states near the Fermi level (E-F) are localized due to the strong disorder caused by the random distribution of Na+ ions in WO3 lattice. Due t...

  6. Reduced ternary molybdenum and tungsten sulfides and hydroprocessing catalysis therewith

    Science.gov (United States)

    Hilsenbeck, Shane J.; McCarley, Robert E.; Schrader, Glenn L.; Xie, Xiaobing

    1999-02-16

    New amorphous molybdenum/tungsten sulfides with the general formula M.sup.n+.sub.2x/n (L.sub.6 S.sub.8)S.sub.x, where L is molybdenum or tungsten and M is a ternary metal, has been developed. Characterization of these amorphous materials by chemical and spectroscopic methods (IR, Raman, PES) shows that the (M.sub.6 S.sub.8).sup.0 cluster units are present. Vacuum thermolysis of the amorphous Na.sub.2x (Mo.sub.6 S.sub.8)S.sub.x .multidot.yMeOH first produces poorly crystalline NaMo.sub.6 S.sub.8 by disproportionation at 800.degree. C. and well-crystallized NaMo.sub.6 S.sub.8 at .gtoreq. 900.degree. C. Ion-exchange of the sodium material in methanol with soluble M.sup.2+ and M.sup.3+ salts (M=Sn, Co, Ni, Pb, La, Ho) produces the M.sup.n+.sub.2x/n (Mo.sub.6 S.sub.8)S.sub.x .multidot.yMeOH compounds. Additionally, the new reduced ternary molybdenum sulfides with the general formula M.sup.n+.sub.2x/n Mo.sub.6 S.sub.8+x (MeOH).sub.y ›MMOS! (M=Sn, Co, Ni) is an effective hydrodesulfurization (HDS) catalyst both as-prepared and after a variety of pretreatment conditions. Under specified pretreatment conditions with flowing hydrogen gas, the SnMoS type catalyst can be stabilized, and while still amorphous, can be considered as "Chevrel phase-like" in that both contain Mo.sub.6 S.sub.8 cluster units. Furthermore, the small cation NiMoS and CoMoS type pretreated catalyst showed to be very active HDS catalysts with rates that exceeded the model unpromoted and cobalt-promoted MoS.sub.2 catalysts.

  7. On tungsten technologies and qualification for DEMO

    International Nuclear Information System (INIS)

    Tungsten alloys are considered prime candidates for the in-vessel components directly facing the plasma. For example, in the HEMJ helium cooled divertor design tiles may be operated at temperatures up to 1700 deg. C, supported by a structure partially consisting of tungsten at temperatures from 600 to 1000 deg. C, and connected to a HT steel structure. The tungsten armoured primary wall is operated at 500-900 deg. C. Irradiation doses will be few tens dpa at minimum, but FPR requirements for plants availability will stretch these targets. Recently injection moulding technology was developed for pure tungsten and representative parts were manufactured for ITER monobloc divertors and DEMO HEMJ thimbles. The major advantages for this technology are the efficient use of material feedstock/resources and the intrinsic possibility to produce near-finished product, avoiding machining processes that are costly and may introduce surface defects deteriorating the component in service performance. It is well suited for mass-manufacturing of components as well known in e.g. lighting industries. To further qualify this material technology various specimen types were produced with processing parameters identical to the components, and tested successfully, showing the high potential for implementation in (fusion) devices. Furthermore, the engineering approach can clearly be tailored away from conventional design and manufacturing technologies based on bulk materials. The technology is suitable for shaping of new W-alloys and W-ODS variants as well. Basically this technology allows a particular qualification trajectory. There is no need to produce large batches of material during the material development and optimization stage. For the verification of irradiation behaviour in the specific neutron spectra, there is a further attractive feature to use e.g. isotope tailored powders to adjust to available irradiation facilities like MTR's. In addition the ingrowth of transmutation

  8. Experimental setup for tungsten transport studies at the NSTX tokamak

    International Nuclear Information System (INIS)

    Tungsten particles have been introduced into the National Spherical Torus Experiment (NSTX) in Princeton with the purpose to investigate the effects of tungsten injection on subsequent plasma discharges. An experimental setup for the study of tungsten particle transport is described where the particles are introduced into the tokamak using a modified particle dropper, otherwise used for lithium-powder injection. An initial test employing a grazing-incidence extreme ultraviolet spectrometer demonstrates that the tungsten-transport setup could serve to infer particle transport from the edge to the hot central plasmas of NSTX.

  9. Boron carbide coating deposition on tungsten and testing of tungsten layers and coating under intense plasma load

    Energy Technology Data Exchange (ETDEWEB)

    Airapetov, A. A.; Begrambekov, L. B., E-mail: lbb@plasma.mephi.ru [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) (Russian Federation); Buzhinskiy, O. I. [State Research Center Troitsk Institute for Innovation and Fusion Research (TRINITI) (Russian Federation); Grunin, A. V.; Gordeev, A. A.; Zakharov, A. M.; Kalachev, A. M.; Sadovskiy, Ya. A.; Shigin, P. A. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) (Russian Federation)

    2015-12-15

    A device intended for boron carbide coating deposition and material testing under high heat loads is presented. A boron carbide coating 5 μm thick was deposited on the tungsten substrate. These samples were subjected to thermocycling loads in the temperature range of 400–1500°C. Tungsten layers deposited on tungsten substrates were tested in similar conditions. Results of the surface analysis are presented.

  10. Boron carbide coating deposition on tungsten and testing of tungsten layers and coating under intense plasma load

    Science.gov (United States)

    Airapetov, A. A.; Begrambekov, L. B.; Buzhinskiy, O. I.; Grunin, A. V.; Gordeev, A. A.; Zakharov, A. M.; Kalachev, A. M.; Sadovskiy, Ya. A.; Shigin, P. A.

    2015-12-01

    A device intended for boron carbide coating deposition and material testing under high heat loads is presented. A boron carbide coating 5 μm thick was deposited on the tungsten substrate. These samples were subjected to thermocycling loads in the temperature range of 400-1500°C. Tungsten layers deposited on tungsten substrates were tested in similar conditions. Results of the surface analysis are presented.

  11. {sup 14}C dating of the Early to Late Bronze Age stratigraphic sequence of Aegina Kolonna, Greece

    Energy Technology Data Exchange (ETDEWEB)

    Wild, E.M., E-mail: Eva.Maria.Wild@univie.ac.a [VERA Laboratory, Faculty of Physics - Isotope Research, University of Vienna, Waehringer Strasse 17, A-1090 Wien (Austria); Gauss, W. [Austrian Archaeological Institute at Athens, Leof. Alexandras 26, Gr10683 Athens (Greece); Forstenpointner, G. [University of Veterinary Medicine Vienna, Dept. of Pathobiology, Institute of Anatomy, Unit on Archaeozoology and Comparative Morphology, Veterinaerplatz 1, A-1210 Vienna (Austria); Lindblom, M. [Dept. of Archaeology and Ancient History Uppsala, University Box 626, SE-751 26 Uppsala (Sweden); Smetana, R. [Altertumswissenschaften, University of Salzburg, Residenzplatz 1/I, A-5020 Salzburg (Austria); Steier, P. [VERA Laboratory, Faculty of Physics - Isotope Research, University of Vienna, Waehringer Strasse 17, A-1090 Wien (Austria); Thanheiser, U. [Vienna Institute for Archaeological Science (VIAS), Althanstrasse 14, A-1090 Vienna (Austria); Weninger, F. [VERA Laboratory, Faculty of Physics - Isotope Research, University of Vienna, Waehringer Strasse 17, A-1090 Wien (Austria)

    2010-04-15

    Aegina Kolonna, located in the center of the Saronic Gulf in the Aegean Mediterranean (Greece), is one of the major archaeological sites of the Aegean Bronze Age with a continuous stratigraphic settlement sequence from the Late Neolithic to the Late Bronze Age. Due to its position next to the maritime cross roads between central mainland Greece, the northeast Peloponnese, the Cyclades and Crete, the island played an important role in the trade between these regions. In the course of new excavations, which focused on the exploration of the Early, Middle and Late Bronze Age at Kolonna, several short lived samples from different settlement phases have been {sup 14}C-dated with the AMS method at the VERA laboratory. Bayesian sequencing of the {sup 14}C data according to the stratigraphic position of the samples in the profile was performed to enable estimates of the transition time between the cultural phases. The Aegina Kolonna {sup 14}C sequence is one of the longest existing so far for the Aegean Bronze Age, and therefore of major importance for the absolute Bronze Age chronology in this region. Preliminary results indicate that the Middle Helladic period seems to have started earlier and lasted longer than traditionally assumed. Further, at the present stage of our investigation we can give also a very tentative time frame for the Santorini volcanic eruption which seems to be in agreement with the science derived VDL date.

  12. Lead isotopic study of Shang Dynasty bronzes (13-11 B.C.) and their ore sources

    International Nuclear Information System (INIS)

    The Shang Dynasty civilization in China is based on the development of the bronze techniques. A large amount of Shang Dynasty bronzes, excavated from Jiangxi, Hubei and Henan Provinces, have become a focus of world attention. However, the Shang Dynasty center was located at Zhenzhou and Anyang city areas, Henan Province, where no large copper ores have been found so far. Therefore, where did the huge ore material for casting the bronzes come from? It is an unsettled question paid attention by the archaeologists and scientists. 35 Shang Dynasty bronzes and 21 copper and lead ore materials aged in the Shang-Zhou Dynasty, the Spring-Autumn Period and the modern time, have been measured by the use of mass spectrometry. Based upon lead isotopic ratios, the ore material for casting the bronzes with the middle isotopic ratios of 207Pb/206Pb ranged in 0.8∼0.9 could come from the ancient copper mine of Tongling, Jiangxi Province and Tong Lushan , Hubei Province and that with the high isotopic ratios (>0.9) could be from the northern part of the Shang Empire, called 'Gongfang' in the historical records, e.g. today's Hebei and Liaoning Provinces. the others with the low isotopic ratios (238U/204Pb in the ore flux or in the magma

  13. Dialysate sodium and sodium gradient in maintenance hemodialysis: a neglected sodium restriction approach?

    OpenAIRE

    Munoz Mendoza, Jair; Sun, Sumi; Chertow, Glenn M.; Moran, John, (Thesis); Doss, Sheila; Schiller, Brigitte

    2011-01-01

    Background. A higher sodium gradient (dialysate sodium minus pre-dialysis plasma sodium) during hemodialysis (HD) has been associated with sodium loading; however, its role is not well studied. We hypothesized that a sodium dialysate prescription resulting in a higher sodium gradient is associated with increases in interdialytic weight gain (IDWG), blood pressure (BP) and thirst.

  14. Pioneering farmers cultivating new lands in the North – The expansion of agrarian societies during the Neolithic and Bronze Age in Scandinavia

    DEFF Research Database (Denmark)

    Sørensen, Lasse

    2012-01-01

    Pioneering farmers cultivating new lands in the North – The expansion of agrarian societies during the Neolithic and Bronze Age in Scandinavia......Pioneering farmers cultivating new lands in the North – The expansion of agrarian societies during the Neolithic and Bronze Age in Scandinavia...

  15. Fabrication of tungsten and tungsten alloy and its high heat load testing for fusion applications

    International Nuclear Information System (INIS)

    Tungsten is one of the most promising candidate materials for an application as plasma facing material (PFM) in future thermonuclear fusion devices. In the divertor region PFM will be exposed to very severe heat load conditions. Steady state heat loads will be around 5 MW/m2 - 10 MW/m2 and in some parts of the divertor even 20 MW/m2 for short periods. These steady state heat loads are accompanied by transient events such as edge localised modes (ELMs), vertical displacement events (VDEs) and plasma disruptions which deposit very high heat loads of up to several MJ/m2 on the PFMs. Important properties which enable tungsten to withstand such environmental conditions are its high melting point, high thermal conductivity and low erosion rate. In present study, we have fabricated Pure Tungsten (W) and Tungsten +1wt. % La2O3 (WL) pallets of size 50 mm (dia) and 9 mm (height) through Powder Metallurgical process using graphite mould and sintered in Direct Sintering Press (DSP) at 2390 °C with 40 MPa pressing force. The crack formations and surface modification behaviours under transient high heat load condition were investigated. Detailed characterization of the exposed sample for its various properties evaluation will be discussed and presented in the paper

  16. Interfacial fracture behavior of tungsten wire/tungsten matrix composites with copper-coated interfaces

    International Nuclear Information System (INIS)

    The potential application of tungsten as a structural material has been strongly restricted by inherent brittleness. The hitherto metallurgical efforts to improve tungsten toughness seem to be still less matured. The authors have been exploring a novel toughening technique based on reinforcement by tungsten wires. Toughness is supposed to be enhanced through the energy dissipation at the wire/matrix interfaces which is caused by the controlled crack deflection and friction. In this work, we focus on two kinds of copper coatings for interface engineering, namely, copper single-layer and copper/tungsten multi-layer. Single-filament composites were fabricated using magnetron sputtering and CVD process. The interfacial parameters were identified by means of fiber push-out test and microscopic fracture features were investigated. In this paper the results from the extensive push-out experiments are presented together with the fractographs. Finite element simulation was also carried out to estimate the plastic strain of the copper layer. Essential role of the significant plastic deformation in the overall failure behavior is highlighted.

  17. CALICE silicon-tungsten electromagnetic calorimeter

    Indian Academy of Sciences (India)

    G Mavromanolakis

    2007-12-01

    A highly granular electromagnetic calorimeter prototype based on tungsten absorber and sampling units equipped with silicon pads as sensitive devices for signal collection is under construction. The full prototype will have in total 30 layers and be read out by about 10000 Si cells of 1 × 1 cm2. A first module consisting of 14 layers and depth of 7.2 0 at normal incidence, having in total 3024 channels of 1 cm2, was tested recently with - beam. We describe the prototype and discuss some preliminary testbeam results on its performance with respect to position resolution, response inhomogeneity and transverse containment.

  18. Cyclic creep in dispersion strengthened tungsten

    International Nuclear Information System (INIS)

    Cyclic creep results are reported for non-sag tungsten wires having an interlocking grain structure with a large grain aspect ratio (GAR > 50). The mechanism of creep under the conditions of the present study was similar to the creep mechanism operating in filaments of incandescent lamps with an inert fill gas. A marked decrease in the effective creep rate were found to occur for cyclic creep, if the period of the maximum load was short with respect to the period of the minimum load. The comparison was based on the time at maximum load with respect to the corresponding static creep rate, as usual. 13 refs., 2 tabs. (Author)

  19. Spectrophotometric determination of tungsten with salicylic acid

    International Nuclear Information System (INIS)

    The method comprises the complexation of tungsten with salicylic acid in concentrated sulphuric acid yielding a reddish color. The maximum absorbance of the complex lies within 410-420 nm, 420 nm being the chosen wavelenght. The final concentration of salicylic acid is 0,080 g/ml. The sensitivity is 0,13 μg W(%T)-1 ml-1. Titanium, vanadium, rhenium, niobium and molybdenum interferes and must be separated, titanium being the strongest interferent. The separation procedures, advantages of the process, stoichiometric relations and equilibrium constant are discussed. (Author)

  20. Tungsten acetonitrile complexes, containing nitrosyl ligand

    International Nuclear Information System (INIS)

    Synthesized are tungsten acetonitrile derivatives, containing nitrosyl ligand. In a course of boiling W(CO)4(NO)I-(1) at the excess of acetonitrile there is formed bis-(acetonitrile)-dicarbonilenitrosyltungsteniod-(2): W(CO)4(NO)I+2CH3CN → 2CO+(CH3CN)2W(CO)2(NO)I-(2). Investigation in reactionary ability of compound (2) is carried out. It is shown that at the reaction of acetonitrile complex (2) with two equivalents of triphenylphosphine depending on reaction conditions formed is a number of products

  1. Tungsten imido catalysts for selective ethylene dimerisation.

    Science.gov (United States)

    Wright, Christopher M R; Turner, Zoë R; Buffet, Jean-Charles; O'Hare, Dermot

    2016-02-14

    A tungsten imido complex W(NDipp)Me3Cl (Dipp = 2,6-(i)Pr-C6H3) is active for the selective dimerisation of ethylene to yield 1-butene under mild conditions. Immobilisation and activation of W(NDipp)Cl4(THF) on layered double hydroxides, silica or polymethylaluminoxane yields active solid state catalysts for the selective dimerisation of ethylene. The polymethylaluminoxane-based catalyst displays a turnover frequency (4.0 molC2H4 molW(-1) h(-1)) almost 7 times that of the homogeneous catalyst. PMID:26779579

  2. Residual stresses in tungsten vapor deposits

    International Nuclear Information System (INIS)

    Using circular specimens values and distribution of peripheral residual stresses in deposits of gaseous tungsten of different thickness on a graphite substrate were determined by the Davidenkov method during electrolytic re oval of metal layers. It is established that the thinner is the deposit the lower is the level of arisnng stresses. After annealing at 750 deg C the stresses decrease by approximately 30 %, and annealing at 1500 deg C results in minimum values. It is assumed that the decrease of the stresses after nnealing at 1500 deg C results from the variations in deposit substructure typical for polygonization processes

  3. Low temperature photoresponse of monolayer tungsten disulphide

    Directory of Open Access Journals (Sweden)

    Bingchen Cao

    2014-11-01

    Full Text Available High photoresponse can be achieved in monolayers of transition metal dichalcogenides. However, the response times are inconveniently limited by defects. Here, we report low temperature photoresponse of monolayer tungsten disulphide prepared by exfoliation and chemical vapour deposition (CVD method. The exfoliated device exhibits n-type behaviour; while the CVD device exhibits intrinsic behaviour. In off state, the CVD device has four times larger ratio of photoresponse for laser on/off and photoresponse decay–rise times are 0.1 s (limited by our setup, while the exfoliated device has few seconds. These findings are discussed in terms of charge trapping and localization.

  4. Xenon-Ion Drilling of Tungsten Films

    Science.gov (United States)

    Garner, C. E.

    1986-01-01

    High-velocity xenon ions used to drill holes of controlled size and distribution through tungsten layer that sheaths surface of controlled-porosity dispenser cathode of traveling wave-tube electron emitter. Controlled-porosity dispenser cathode employs barium/calcium/ aluminum oxide mixture that migrates through pores in cathode surface, thus coating it and reducing its work function. Rapid, precise drilling technique applied to films of other metals and used in other applications where micron-scale holes required. Method requires only few hours, as opposed to tens of hours by prior methods.

  5. Photocatalytic properties of plasma treated tungsten oxide

    Czech Academy of Sciences Publication Activity Database

    Brožek, Vlastimil; Domlátil, J.; Mastný, L.; Šrank, Z.; Janča, J.; Eliáš, M.

    Praha : Česká společnost chemického inženýrství, 2006 - (Novosad, J.), s. 215-P7.71 ISBN 80-86059-45-6. [International Congress of Chemical and Process Engineering CHISA 2006/17th./. Praha (CZ), 27.08.2006-31.08.2006] R&D Projects: GA ČR(CZ) GA104/05/0540 Institutional research plan: CEZ:AV0Z20430508 Keywords : tungsten oxide * photocatalysis * plasma treatment Subject RIV: JK - Corrosion ; Surface Treatment of Materials www.chisa.cz

  6. Low temperature photoresponse of monolayer tungsten disulphide

    International Nuclear Information System (INIS)

    High photoresponse can be achieved in monolayers of transition metal dichalcogenides. However, the response times are inconveniently limited by defects. Here, we report low temperature photoresponse of monolayer tungsten disulphide prepared by exfoliation and chemical vapour deposition (CVD) method. The exfoliated device exhibits n-type behaviour; while the CVD device exhibits intrinsic behaviour. In off state, the CVD device has four times larger ratio of photoresponse for laser on/off and photoresponse decay–rise times are 0.1 s (limited by our setup), while the exfoliated device has few seconds. These findings are discussed in terms of charge trapping and localization

  7. Impact of temperature during He+ implantation on deuterium retention in tungsten, tungsten with carbon deposit and tungsten carbide

    Science.gov (United States)

    Oya, Yasuhisa; Sato, Misaki; Li, Xiaochun; Yuyama, Kenta; Fujita, Hiroe; Sakurada, Shodai; Uemura, Yuki; Hatano, Yuji; Yoshida, Naoaki; Ashikawa, Naoko; Sagara, Akio; Chikada, Takumi

    2016-02-01

    Temperature dependence on deuterium (D) retention for He+ implanted tungsten (W) was studied by thermal desorption spectroscopy (TDS) to evaluate the tritium retention behavior in W. The activation energies were evaluated using Hydrogen Isotope Diffusion and Trapping (HIDT) simulation code and found to be 0.55 eV, 0.65 eV, 0.80 eV and 1.00 eV. The heating scenarios clearly control the D retention behavior and, dense and large He bubbles could work as a D diffusion barrier toward the bulk, leading to D retention enhancement at lower temperature of less than 430 K, even if the damage was introduced by He+ implantation. By comparing the D retention for W, W with carbon deposit and tungsten carbide (WC), the dense carbon layer on the surface enhances the dynamic re-emission of D as hydrocarbons, and induces the reduction of D retention. However, by He+ implantation, the D retention was increased for all the samples.

  8. A Preliminary Study of Bronzes in the Kayao Culture%卡约文化青铜器初步研究

    Institute of Scientific and Technical Information of China (English)

    三宅俊彦

    2005-01-01

    A chronological study of its pottery suggests that the Kayao culture remains can be divided into the groups of Huangshui River and Yellow River valleys and each group fall into six phases.On this basis the typology and combination of bronzes in the Kayao culture can be further studied. The results indicate that bronze-making technology in the Huangshui River valley was higher than that in the Yellow River valley, and that the sexual difference of tomb-owners is reflected from the distinction of funeral objects. Furthermore, the chronological study of the Kayao's bronzes provides reference data for dating the phases of this culture. These bronzes possess three categories of cultural elements: the elements of their own, common elements of bronzes in the Central Plains and North China, and those in northern Eurasia.

  9. Hydrogen Permeation Through VPD and CVD Tungsten Films on Palladium

    International Nuclear Information System (INIS)

    Isobar and isotherms were measured for hydrogen permeation through porous tungsten films on palladium, activation energy values were calculated for various Pd-W systems. The analysis of the obtained data and its comparison with the ones for dense tungsten coatings are carried out

  10. Microstructure and tensile properties of tungsten at elevated temperatures

    Science.gov (United States)

    Shen, Tielong; Dai, Yong; Lee, Yongjoong

    2016-01-01

    In order to support the development of the 5 MW spallation target for the European Spallation Source, the effect of fabrication process on microstructure, ductile-to-brittle transition temperature (DBTT), tensile and fracture behaviour of powder-metallurgy pure tungsten materials has been investigated. A hot-rolled (HR) tungsten piece of 12 mm thickness and a hot-forged (HF) piece of about 80 mm thickness were used to simulate the thin and thick blocks in the target. The two tungsten pieces were characterized with metallography analysis, hardness measurement and tensile testing. The HR piece exhibits an anisotropic grain structure with an average size of about 330 × 140 × 40 μm in rolling, long transverse and short transverse (thickness) directions. The HF piece possesses a bimodal grain structure with about 310 × 170 × 70 μm grain size in deformed part and about 25 μm sized grains remained from sintering process. Hardness (HV0.2) of the HR piece is slightly greater than that of the HF one. The ductility of the HR tungsten specimens is greater than that of the HF tungsten. For the HF tungsten piece, specimens with small grains in gauge section manifest lower ductility but higher strength. The DBTT evaluated from the tensile results is 250-300 °C for the HR tungsten and about 350 °C for the HF tungsten.

  11. Behavior of tungsten carbide in water stabilized plasma

    Czech Academy of Sciences Publication Activity Database

    Brožek, Vlastimil; Matějíček, Jiří; Neufuss, Karel

    2007-01-01

    Roč. 7, č. 4 (2007), s. 213-220. ISSN 1335-8987 R&D Projects: GA ČR(CZ) GA104/05/0540 Institutional research plan: CEZ:AV0Z20430508 Keywords : water stabilized plasma * tungsten carbide * tungsten hemicarbide * decarburization Subject RIV: BL - Plasma and Gas Discharge Physics

  12. Processing of tungsten scrap into powders by electroerosion disintegration

    International Nuclear Information System (INIS)

    Utilization of tungsten and tungsten alloy swarf and other waste and also of rejected and worn parts is a matter of great importance in view of the shortage of this metal. The authors examine the electroerosion (EE) disintegration of tungsten in water as a means of utilizing swarf and other loose waste. Unlike chemical methods, EE disintegration ensures ecological purity since there are no effluent waters or toxic discharges. Swarf and trimmings of rods of diameters up to 20 mm obtained after the lathe-turning of tungsten bars sintered from PVN and PVV tungsten powders were disintegrated in water at room temperature between tungsten electrodes. The phase composition of the powder was studied using FeK /SUB alpha/ radiation, by x-ray diffraction methods in a DRON-2 diffractometer with a graphite monochromator on the secondary beam. When tungsten is heated to boiling during EE disintegration, the impurities present in it can evaporate and burn out. Thus, tungsten powder produced by EE disintegration can be purer than the starting metal

  13. Development of a high Jc bronze route Nb3Sn conductor using Nb-Ta composite filaments

    International Nuclear Information System (INIS)

    For superconducting magnets generating fields above 10 tesla, multifilamentary Nb3Sn is the conductor of choice. There are two widely used methods of manufacturing these conductors, namely the internal Sn route and bronze process. Bronze route conductors can yield long piece lengths with consistent performances due to the mechanical compatibilities of the components compared to internal Sn conductors. Internal Sn designs require a soft low melting point Sn and is more difficult to be co-processed with the significantly harder Nb filaments. This paper summarizes the development of a bronze route Nb3Sn wire with high Jc using Nb-Ta composite filaments for use in advanced projects such as the International Thermonuclear Experimental Reactor (ITER)

  14. The lattice parameter of α-bronzes as a function of solute content: application to archaeological materials

    International Nuclear Information System (INIS)

    The lattice parameter of Cu substitutional solid solution--α-phase--has been studied in relation with the solute content. The investigation was conducted on pure binary Cu-Sn, industrial Cu-Sn-Zn alloys and archaeological bronzes. Lattice parameters and elemental compositions of the α-phase have been determined by X-ray diffraction and X-ray spectrometry. A linear relation between the unit cell constant and the atomic tin equivalent content in the α-phase has been evidenced and characterised, in fair agreement with Vegard's law. Addition of lead and trace elements has no significant effect on the results. Therefore, the tin equivalent content of the α-phase can be determined from XRD evaluation of the lattice parameter. As a consequence, a new approach is proposed for setting composition standards in α-(Cu-Sn) and α-(Cu-Sn-Zn) bronzes and application to characterization of ancient bronzes is discussed

  15. Solubilities of sodium nitrate, sodium nitrite, and sodium aluminate in simulated nuclear waste

    International Nuclear Information System (INIS)

    Solubilities were determined for sodium nitrate, sodium nitrite, and sodium aluminate in synthetic nuclear waste liquor. Solubilities were determined as a function of temperature and solution composition (concentrations of sodium hydroxide, sodium nitrate, sodium nitrite, and sodium aluminate). Temperature had the greatest effect on the solubilities of sodium nitrate and sodium nitrite and a somewhat lesser effect on sodium aluminate solubility. Hydroxide had a great effect on the solubilities of all three salts. Other solution components had minor effects. 2 references, 8 figures, 11 tables

  16. Sodium fire suppression

    International Nuclear Information System (INIS)

    Ignition and combustion studies have provided valuable data and guidelines for sodium fire suppression research. The primary necessity is to isolate the oxidant from the fuel, rather than to attempt to cool the sodium below its ignition temperature. Work along these lines has led to the development of smothering tank systems and a dry extinguishing powder. Based on the results obtained, the implementation of these techniques is discussed with regard to sodium fire suppression in the Super-Phenix reactor. (author)

  17. Plasma spray forming of tungsten coatings on copper electrodes

    Institute of Scientific and Technical Information of China (English)

    JIANG Xian-liang(蒋显亮); F.Gitzhofer; M.I.Boulos

    2004-01-01

    Both direct current dc plasma and radio frequency induction plasma were used to deposit tungsten coatings on copper electrodes. Fine tungsten powder with mean particle size of 5μm and coarse tungsten powder with particle size in the range from 45 μm to 75 μm were used as plasma spray feedstock. It is found that dc plasma is only applicable to spray the fine tungsten powder and induction plasma can be used to spray both the coarse powder and the fine powder. The tungsten coating deposited by the induction plasma spraying of the coarse powder is extremely dense. Such a coating with an interlocking structure and an integral interface with the copper substrate demonstrates high cohesion strength and adhesion strength.

  18. Corrosion of high-density sintered tungsten alloys. Part 2

    International Nuclear Information System (INIS)

    The behaviour of four high-density sintered tungsten alloys has been evluated and compared with that of pure tungsten. Rates of corrosion during the cyclic humidity and the salt mist tests were ascertained from weight loss measurements. Insight into the corrosion mechanism was gained from the nature of the corrosion products and an examination of the corroded surfaces. In the tests, the alloy 95% W, 2.5% Ni, 1.5% Fe was the most corrosion resistant. The data showed that copper as an alloying element accelerates corrosion of tungsten alloys. Both attack on the tungsten particles and the binder phase were observed together with tungsten grain loss. 6 refs., 3 tabs.,

  19. Tungsten recycling in the United States in 2000

    Science.gov (United States)

    Shedd, Kim B.

    2011-01-01

    This report, which is one of a series of reports on metals recycling, defines and quantifies the flow of tungsten-bearing materials in the United States from imports and stock releases through consumption and disposition in 2000, with particular emphasis on the recycling of industrial scrap (new scrap) and used products (old scrap). Because of tungsten's many diverse uses, numerous types of scrap were available for recycling by a wide variety of processes. In 2000, an estimated 46 percent of U.S. tungsten supply was derived from scrap. The ratio of tungsten consumed from new scrap to that consumed from old scrap was estimated to be 20:80. Of all the tungsten in old scrap available for recycling, an estimated 66 percent was either consumed in the United States or exported to be recycled.

  20. Spreading of Ni - Fe - W melts over polycrystalline tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Yupko, V.L.; Minakova, R.V.; Kolchin, O.P.; Vodop' yanova, L.S.; Monastyreva, N.I.; Vojtenko, V.L. (AN Ukrainskoj SSR, Kiev. Inst. Problem Materialovedeniya)

    1983-09-01

    The method of filming was employed to study the spread over dense and porous polycrystalline tungsten of Ni-Fe-W melts. When tungsten amount grows and the W-(Ni-Fe-W) system approaches the thermodynamic equilibrium state the melts spread deteriorates; in case of porous tungsten it is worse than in case of dense one. The observed porosity effect on the spread testifies to intensification of the liquid motion turbulence. Difference in the spread over polycrystalline tungsten between melts with a constant tungsten content (24%) and with the Ni:Fe ratio varying over wide ranges is within the limits of the experimental error, which is due to similar physicochemical properties of nickel and iron.

  1. New doped tungsten cathodes. Applications to power grid tubes

    International Nuclear Information System (INIS)

    Thermionic emission behavior of tungsten/tungsten carbide modified with rare earth (La, Ce, Y) oxides is examined on account of suitability to deliver important current densities in a thermo-emissive set up and for long lifetime. Work functions of potential cathodes have been determined from Richardson plots for La2O3 doped tungsten and for tungsten covered with variable compositions rare earth tungstates. The role of platinum layers covering the cathode was also examined. Given all cathodes containing mainly lanthanum oxides were good emitters, emphasis was put on service lifetime. Comparisons of lifetime in tungsten doped with rare earth oxides and with rare earth tungstates show that microstructure of the operating cathodes may play the major role in the research of very long lifetime cathodes. Based on these results, tests still running show lifetime compatible with power grid tubes applications. (author)

  2. A study on consumable aided tungsten indirect arc welding

    Institute of Scientific and Technical Information of China (English)

    Wang Jun; Wang Yuxin; Feng Jicai

    2009-01-01

    A consumable aided tungsten indirect arc welding method has been studied. This method is different from the traditional TIG welding because it introduces an MIG welding torch into the traditional TIG welding system. An indirect arc is generated between the consumable electrode of the MIG welding torch and the tungsten electrode of the TIG welding torch, but not generated between the tungsten electrode of the welding torch and the base metal. Welding current flows from the consumable electrode to the tungsten electrode in the free-burning indirect arc. The consumable aided tungsten indirect arc welding not only rapidly melts the welding wire but also effectively restrains the excessive fusion of the base metal. The welding experiment and the theoretical analysis confirm that this method can obtain a high deposition rate and a low dilution ratio during the welding process.

  3. Thermophysical properties of sodium

    International Nuclear Information System (INIS)

    Thermophysical properties of sodium for reactor safety studies are presented. Subcooled, superheated and saturated properties are given. A summary of the thermophysical properties is given in tabular form

  4. Analysis of the Portevin - Le Chatelier effect in tin bronzes at elevated temperatures

    Directory of Open Access Journals (Sweden)

    W. Ozgowicz

    2008-12-01

    Full Text Available Purpose: The aim of the present paper is the determination of the effect of the chemical composition and temperature of deformation of standardized tin bronzes and bronze modified with zirconium on the Portevin – Le Chatelier (PLC phenomenon, mainly basing on the shape of stress-strain curves within the temperature range of 100-300oC and observations of their structure. The reasons of the occurrence of such en effect are so far no fully known and explained and the opinions concerning is physical basis vary.Design/methodology/approach: Of essential design in this research is determination of the dependence of PLC effect on the chemical composition, temperature and strain rate and the preliminary heat treatment and grain size. The main method used in this investigation is tensile test at elevated temperature.Findings: The main conclusions are following: the PLC effect on tin bronzes with a micro-addition of zirconium in an amount of 0.01-0.05% depends the temperature of deformation in the tensile test in the range of 100-300oC and the chemical composition of the alloys; the type of serration revealed on the σ–ε curve depend mainly on the temperature of deformation and can be differ during the respective stages of the analyzed curves.Practical implications: In this paper implications for practice are not taken into consideration.Originality/value: In this paper an additive type of serration observed on the curves σ–ε, denoted by the symbol D, is new.

  5. On the degradation factors of an archaeological bronze bowl belonging to a private collection

    International Nuclear Information System (INIS)

    Highlights: • Bronze bowl from Iran belonging to a private collection. • Style and manufacturing consistent with the Achaemenid art (I century B.C.). • Modified Type I patinas. • Apparently continuous tenorite layer at the metal surface on the internal bowl side. • Fragmentation attributed to a severe intergranular attack. - Abstract: A bronze bowl belonging to a private collection, stylistically consistent with the Achaemenid art was investigated to determine the cause of the artwork local fragmentation. The corrosion products were characterised by energy dispersive X-ray fluorescence spectrometry (EDXRF), Raman spectroscopy and scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). The last technique was also used to determine the chemical composition of the alloy. The metallographic analysis showed that the bowl was obtained from a monophasic bronze alloy, containing about 11% tin and other elements in traces. The presence of an inhomogeneous microstructure with both thermal twin bands and slip lines was consistent with multiple hammering steps followed by partial annealing treatments. On the bowl a very limited chloride contamination was observed and chlorides were never detected in proximity to the metal. These findings and the morphological/compositional characteristics of the patinas permitted to classify that on the internal side of the bowl as a modified Type I morphology, while the patina on the external side of the bowl was less compact, so that it was judged borderline between a “noble” patina and a disfiguring one. On this side, a significant intergranular attack was found, reputed responsible for the fragmentation occurred

  6. On the degradation factors of an archaeological bronze bowl belonging to a private collection

    Energy Technology Data Exchange (ETDEWEB)

    Soffritti, C., E-mail: chiara.soffritti@unife.it [TekneHub, Department of Architecture, University of Ferrara, Via Quartieri 8, 44122 Ferrara (Italy); Department of Engineering, University of Ferrara, Via Saragat 1, 44122 Ferrara (Italy); Fabbri, E., E-mail: elettra.fabbri@unife.it [Department of Engineering, University of Ferrara, Via Saragat 1, 44122 Ferrara (Italy); Merlin, M., E-mail: mattia.merlin@unife.it [Department of Engineering, University of Ferrara, Via Saragat 1, 44122 Ferrara (Italy); Garagnani, G.L., E-mail: gian.luca.garagnani@unife.it [Department of Engineering, University of Ferrara, Via Saragat 1, 44122 Ferrara (Italy); “A. Daccò” Corrosion and Metallurgy Study Centre, University of Ferrara, Via Saragat 1, 44122 Ferrara (Italy); Monticelli, C., E-mail: cecilia.monticelli@unife.it [Department of Engineering, University of Ferrara, Via Saragat 1, 44122 Ferrara (Italy); “A. Daccò” Corrosion and Metallurgy Study Centre, University of Ferrara, Via Saragat 1, 44122 Ferrara (Italy)

    2014-09-15

    Highlights: • Bronze bowl from Iran belonging to a private collection. • Style and manufacturing consistent with the Achaemenid art (I century B.C.). • Modified Type I patinas. • Apparently continuous tenorite layer at the metal surface on the internal bowl side. • Fragmentation attributed to a severe intergranular attack. - Abstract: A bronze bowl belonging to a private collection, stylistically consistent with the Achaemenid art was investigated to determine the cause of the artwork local fragmentation. The corrosion products were characterised by energy dispersive X-ray fluorescence spectrometry (EDXRF), Raman spectroscopy and scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). The last technique was also used to determine the chemical composition of the alloy. The metallographic analysis showed that the bowl was obtained from a monophasic bronze alloy, containing about 11% tin and other elements in traces. The presence of an inhomogeneous microstructure with both thermal twin bands and slip lines was consistent with multiple hammering steps followed by partial annealing treatments. On the bowl a very limited chloride contamination was observed and chlorides were never detected in proximity to the metal. These findings and the morphological/compositional characteristics of the patinas permitted to classify that on the internal side of the bowl as a modified Type I morphology, while the patina on the external side of the bowl was less compact, so that it was judged borderline between a “noble” patina and a disfiguring one. On this side, a significant intergranular attack was found, reputed responsible for the fragmentation occurred.

  7. Highly efficient ablation of metastatic breast cancer using ammonium-tungsten-bronze nanocube as a novel 1064 nm-laser-driven photothermal agent.

    Science.gov (United States)

    Guo, Chongshen; Yu, Haijun; Feng, Bing; Gao, Weidong; Yan, Mei; Zhang, Zhiwen; Li, Yaping; Liu, Shaoqin

    2015-06-01

    Photothermal ablation (PTA) therapy has been viewed as an invasive option for cancer therapy with minimal deconstruction of healthy tissues. In this study, a potent candidate of (NH4)xWO3 nanocube was developed for PTA treatment of metastatic breast cancer in the second near-infrared (NIR) window. It was found that the as-synthesized (NH4)xWO3 nanocube had significant photoabsorption across the whole NIR window of 780-2500 nm and exhibited considerable photo-heat conversion efficiency. Moreover, the as-prepared (NH4)xWO3 nanocube displayed good biocompatibility and high cellular uptake efficiency through endocytosis pathway without nuclei entry. The PTA study employing 1064 nm laser in the second NIR window revealed that (NH4)xWO3 nanocubes induced significant cell necrosis and apoptosis by producing obviously hyperthermia effect inside cancer cells. Using an orthotopicly implanted breast tumor model, it demonstrated that the (NH4)xWO3 nanocube was a promising photothermal agent for effective ablation of solid tumors and suppressing their distant metastasis. PMID:25818447

  8. Computed Tomography and Computed Radiography of late Bronze Age Cremation Urns from Denmark

    DEFF Research Database (Denmark)

    Harvig, Lise Lock; Lynnerup, Niels; Amsgaard Ebsen, Jannie

    2012-01-01

    To improve methods used to study prehistoric cremation rituals, cremation urns from the Danish late Bronze Age were examined using Computed Tomography and Computed Radiography (Digital X-ray). During microexcavation, the digital images were used as registration tool. Our results suggest that...... osteological ageing and sexing are more accurate when combining CT-images with excavated remains. Digital volume rendering further enables a compromised estimation of original cremation weight. Microexcavation is clearly a primary cause of bone fragmentation. Cremated remains affected by lower cremation...

  9. Compositional analyses of a Reutlingen Bronze Age sword discovered at Giurgiu, Romania

    CERN Document Server

    Olariu, A; Avram, A; Badica, T; Olariu, Agata; Alexandrescu, Emilian; Avram, Alexandru; Badica, Teodor

    2003-01-01

    The compositional scheme of a Bronze Age sword, found near the town of Giurgiu in Romania has been determined by the method of particle-induced X-ray emission (PIXE), at the tandem accelerator of the National Institute for Physics and Nuclear Engineering from Bucharest, Magurele, Romania. The results of the analyses and the comparison with the composition of other swords from the same geographic area, the Danubian plane from Bulgaria and Transylvania regions, show that the sword from Giurgiu could be relatively associated with the swords from Bulgaria, having also the same stylistic, temporal and geographical similitude.

  10. Strength of b3Sn intermetallic layers in bronze/niobium filaments composite material

    International Nuclear Information System (INIS)

    Tension tests have been used to estimate the strength of Nb3Sn intermetallic layer formed at the filament/matrix interface in the composite superconducting material, bronze(13 at.%Sn)/niobium filament. It is noted that the layer destruction starts with the formation of a group of cracks placed at a similar interval from each other, which are the reason for instability of sUperconducting properties in the composite system. The formula is given that connects the fracturing and superconducting properties, from which it follows that with the increase of layer thickness and its strength, the fracturing reduces, while superconducting properties improve

  11. ARCHAEOMETALLURGICAL STUDIES OF SPEAR HEADS AND ARROW HEADS OF THE MIDDLE BRONZE AGE SITES OF AZERBAIJAN

    OpenAIRE

    Hasanova, Aziza

    2015-01-01

    Quantitative spectroscopy analysis of spear heads and arrow heads of Middle Bronze Age sites of Azerbaijan (second part of the III to the middle of the II millennium BC) has been made to determine the type of the alloy taking into account the accepted limits of natural impurity in metals ( - 0.5% and more). The analyses have shown that copper is the basic materials in all of them. Metallurgical classification the results of sixteen analysis spear heads have shown three of them made of arsenic...

  12. Electrolytic surface hardening of steel,castiron and aluminium-bronze

    Directory of Open Access Journals (Sweden)

    Suhas Keshav Paknik a r

    2006-08-01

    Full Text Available Electrolytic hardening process w as developed in USSR in the 1950s. The process w as developed but w as not com m ercially exploited. There is no evidence of w ork done on this process in India. The author has done this originalw ork applied to different m aterials like steel, castiron and alum inum -bronze.This paper gives details ofm icrostructuraltransform ations along w ith hardness value achieved. There is vitalscope for this process to becom e viable for surfacehardening and selective hardening ofsm allcom ponents.

  13. Synthesis and structure of a quadratic oxygen bronze containing uranium of valence six

    International Nuclear Information System (INIS)

    (Nb7.6U2.4)(Ba5.2K0.8)O30 is a quadratic bronze with space group P4bm and lattice parameters a = 12.608(5) and c = 4.012(2) A, Z=1. The structure of a single crystal was refined to R = 0.056 (RW = 0.072) for 967 independent reflections with I ≥ 3σI. The U6+ ion is located inside octahedral sites with Nb5+ and Nb4+. (orig.)

  14. The Chalcolithic and the Bronze Age in the river Neiva Basin, NW of Portugal

    OpenAIRE

    Magalhães, Marisa Cardoso

    2016-01-01

    Relatório de estágio de mestrado em Arqueologia O presente relatório deseja expor os resultados da investigação sobre o Calcolítico e a Idade do Bronze da bacia do Neiva, desenvolvida durante o segundo ano de Mestrado em Arqueologia na Universidade do Minho. Relativamente a estes períodos cronológicos podemos destacar a diversidade de estratégias de povoamento, com tendências para ocupações de locais de menor altitude e mais próximas de vales. Estas comunidades que se estabelec...

  15. Homogenous Silver-Tungsten Composite Production for Electrical Contacts

    Directory of Open Access Journals (Sweden)

    Shahid M. Azhar

    2015-03-01

    Full Text Available Silver-tungsten composite materials have been widely used as medium duty electrical contacts since they offer the advantages of both refractory tungsten (welding and erosion resistance and silver (efficient electro-thermal conductivities. Since there is no alloying between the two elements (Ag and W, the properties of the composite depends on their composition. So for any particular application, a balance must be struck between the desirable properties of the two metals. Both welding and erosion resistance properties of silver-tungsten contacts depend on particle size, morphology and distribution of both elements within the composite, with finer W particles in Ag matrix give better performance. The main objective of this study is to produce an intimately mixed silver-tungsten powder with homogeneous distribution of both phases (silver and tungsten in the composite. Thus, to produce homogenous elemental silver-tungsten powder, the reduction behavior of each tungstate is studied at various reduction temperatures using TGA technique. Based on the results obtained from TGA, the reduction of silver tungstate carried out in two stage reduction process for producing elemental silver-tungsten powder with controlled particle size of tungsten. Also, small quantities of Fe and Co as sinter aids are introduced into tungstates by co-precipitation technique. However, the precipitated Fe and Co doped silver tungstates are reduced to yield Iron and cobalt doped silver-tungsten powders. The effect of Fe and Co on the morphology and particle size of the tungsten is studied using SEM. The reduced products will be used for subsequent sintering experiments to produce high density sintered compact for contact fabrication.

  16. Microstructural characterization and field emission properties of tungsten oxide and titanium-oxide-doped tungsten oxide nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Su, Chia-Hsiang [Department of Mechanical Engineering, Southern Taiwan University of Science and Technology, Tainan, Taiwan (China); Su, Cherng-Yuh, E-mail: cysu@ntut.edu.tw [Department of Mechanical Engineering, National Taipei University of Technology, Taipei, Taiwan (China); Lin, Yan-Fu [Department of Mechanical Engineering, National Taipei University of Technology, Taipei, Taiwan (China)

    2015-03-01

    Tungsten oxide and titanium-oxide-doped tungsten oxide nanowires were synthesized by using the DC magnetron sputtering and infrared furnace annealing processes. Scanning election microscopy (SEM) and transmission electron microscopy (TEM) were utilized to evaluate the topography and sizes. X-ray diffraction (XRD), grazing incidence X-ray diffraction (GI-XRD), and high-resolution transmission electron microscopy (HRTEM) were used to analyze the composition and structure. From the results of HRTEM, it was discovered that the prepared nanowires have a monoclinic single-crystal phase of W{sub 18}O{sub 49} with lattice growth along the (010) lattice plane, and the lattice spacing is 0.378 nm, which agrees with XRD and GI-XRD results. The prepared tungsten oxide and titanium-oxide-doped tungsten oxide nanowires have turn-on voltage of 3.06 V/μm and 1.46 V/μm respectively. They also possess superior field enhancement factors of 5103 and 10667 respectively. Their behavior thus follows the Fowler-Nordheim expression for tunneling. - Highlights: • A simple method to prepare tungsten oxide nanowires by annealing tungsten film. • High aspect ratio of the 1D titanium-oxide-doped tungsten oxide nanowires. • High field enhancement factor of titanium-oxide-doped tungsten oxide nanowires.

  17. Micro-EDXRF surface analyses of a bronze spear head: Lead content in metal and corrosion layers

    Energy Technology Data Exchange (ETDEWEB)

    Figueiredo, E. [Instituto Tecnologico e Nuclear, Estrada Nacional 10, 2686-953 Sacavem (Portugal); Departamento de Conservacao e Restauro, Faculdade de Ciencias e Tecnologia da Universidade Nova de Lisboa, Quinta da Torre, 2829-516 Monte de Caparica (Portugal)], E-mail: elin@itn.pt; Valerio, P.; Araujo, M.F. [Instituto Tecnologico e Nuclear, Estrada Nacional 10, 2686-953 Sacavem (Portugal); Senna-Martinez, J.C. [Instituto de Arqueologia, Faculdade de Letras da Universidade de Lisboa, Cidade Universitaria, Campo Grande, 1600-214 Lisbon (Portugal)

    2007-09-21

    A bronze spear head from Central Portugal dated to Late Bronze Age has been analyzed by non-destructive micro-EDXRF in the metal surface and corrosion layers. The artifact had previously been analyzed using a conventional EDXRF spectrometer having a larger incident beam. The quantification of the micro-EDXRF analyses showed that lead content in corrosion layers can reach values up to four times higher than the content determined in the metal surface. Results obtained with the higher energy incident beam from the EDXRF equipment, although referring mainly to the corrosion layers, seem to suffer some influence from the surface composition of the metallic alloy.

  18. Rheological properties and formation mechanism of DC electric fields induced konjac glucomannan-tungsten gels.

    Science.gov (United States)

    Wang, Lixia; Jiang, Yaoping; Lin, Youhui; Pang, Jie; Liu, Xiang Yang

    2016-05-20

    Konjac glucomannan-tungsten (KGM-T) hydrogel of electrochemical reversibility was successfully produced under DC electric fields in the presence of sodium tungstate. The structure and the effects of sodium tungstate concentration, KGM concentration, voltage and electric processing time on the rheological properties of the gels were investigated. pH experiments showed that KGM sol containing Na2WO4·2H2O in the vicinity of the positive electrode became acidic and the negative electrode basic after the application of DC electric fields. Under acid conditions, WO4(2-) ions transformed into isopoly-tungstic acid ions. FTIR and Raman studies indicated that isopoly-tungstic acid ions absorbed on KGM molecular chain and cross-linked with OH groups at C-6 position on sugar units of KGM. Frequency sweep data showed with increasing sodium tungstate concentration, voltage, and electric processing time, the viscoelastic moduli, i.e., the storage and the loss moduli of the gel increased, whereas an increase in KGM concentration led to a decrease in gel viscoelastic moduli. The temperature sweep measurements indicated the obtained gel exhibited high thermal stability. Finally, the mechanism of gel formation was proposed. Our work may pave the way to use DC electric fields for the design and development of KGM gels as well as polysaccharide gels. PMID:26917402

  19. Freeze-dried tungsten heavy alloys

    International Nuclear Information System (INIS)

    Tungsten heavy alloy powders were produced from freeze-dried aqueous solutions of ammonium metatungstate and, primarily, sulfates of Ni and Fe. The freeze-dried salts were calcined and hydrogen reduced to form very fine, homogenous, low-density, W heavy alloy powders having a coral-like structure with elements of approximately 0.1 μm in diameter. The powders yield high green strength and sinterability. Tungsten heavy alloy powders of 70%, 90%, and 97% W were prepared by freeze drying, compacted, and solid-state (SS) sintered to full density at temperatures as low as 1200 degree C and also at conventional liquid-phase (LP) sintering temperatures. Solid-state sintered microstructures contained polygonal W grains with high contiguity; the matrix did not coat and separate the W grains to form low-contiguity, high-ductility structures. Liquid-phase sintered microstructures were very conventional in appearance, having W spheroids of low contiguity. All of these materials were found to be brittle. High levels of residual S accompanied by segregation of the S to all the microstructural interfaces are principally responsible for the brittleness; problems with S could be eliminated by using Fe and Ni nitrates rather than the sulfates. Unusually high hardness, approaching 48 HRC, was obtained from sintering at 1130 degree C. As-sintered hardness decreases as grain size increases with sintering temperature during SS sintering and with time during LP sintering. 8 refs., 9 figs., 2 tabs

  20. Dynamic compaction of tungsten carbide powder.

    Energy Technology Data Exchange (ETDEWEB)

    Gluth, Jeffrey Weston; Hall, Clint Allen; Vogler, Tracy John; Grady, Dennis Edward

    2005-04-01

    The shock compaction behavior of a tungsten carbide powder was investigated using a new experimental design for gas-gun experiments. This design allows the Hugoniot properties to be measured with reasonably good accuracy despite the inherent difficulties involved with distended powders. The experiments also provide the first reshock state for the compacted powder. Experiments were conducted at impact velocities of 245, 500, and 711 m/s. A steady shock wave was observed for some of the sample thicknesses, but the remainder were attenuated due to release from the back of the impactor or the edge of the sample. The shock velocity for the powder was found to be quite low, and the propagating shock waves were seen to be very dispersive. The Hugoniot density for the 711 m/s experiment was close to ambient crystal density for tungsten carbide, indicating nearly complete compaction. When compared with quasi-static compaction results for the same material, the dynamic compaction data is seen to be significantly stiffer for the regime over which they overlap. Based on these initial results, recommendations are made for improving the experimental technique and for future work to improve our understanding of powder compaction.

  1. 夏商周青铜器铅同位素示踪研究数据库的构建%A Lead Isotope Ratio Data Base of Ancient Chinese Bronzes

    Institute of Scientific and Technical Information of China (English)

    金正耀

    2005-01-01

    A data base of lead isotope ratio of ancient Chinese bronzes is set up. There are 2 888 members, including bronze objects, casting remains, and related ores, etc. in the file. The file contents of data base are made from analysis work on Chinese bronze previously carried out in several laboratories in China, Japan and USA. The main body of the file contents is formed from records, analysis data, reference documents, and images. The data base is designed for sharing information in provenance study on raw metal material for bronze production in China Bronze Age.

  2. Nonlinear Saturable Absorption of Liquid-Exfoliated Molybdenum/Tungsten Ditelluride Nanosheets.

    Science.gov (United States)

    Mao, Dong; Du, Bobo; Yang, Dexing; Zhang, Shengli; Wang, Yadong; Zhang, Wending; She, Xiaoyang; Cheng, Huachao; Zeng, Haibo; Zhao, Jianlin

    2016-03-01

    Molybdenum disulfide (MoS2 ) and tungsten disulfide (WS2 ), two representative transition metal dichalcogenide materials, have captured tremendous interest for their unique electronic, optical, and chemical properties. Compared with MoS2 and WS2 , molybdenum ditelluride (MoTe2 ) and tungsten ditelluride (WTe2 ) possess similar lattice structures while having smaller bandgaps (less than 1 eV), which is particularly interesting for applications in the near-infrared wavelength regime. Here, few-layer MoTe2 /WTe2 nanosheets are fabricated by a liquid exfoliation method using sodium deoxycholate bile salt as surfactant, and the nonlinear optical properties of the nanosheets are investigated. The results demonstrate that MoTe2 /WTe2 nanosheets exhibit nonlinear saturable absorption property at 1.55 μm. Soliton mode-locking operations are realized separately in erbium-doped fiber lasers utilizing two types of MoTe2 /WTe2 -based saturable absorbers, one of which is prepared by depositing the nanosheets on side polished fibers, while the other is fabricated by mixing the nanosheets with polyvinyl alcohol and then evaporating them on substrates. Numerous applications may benefit from the nonlinear saturable absorption features of MoTe2 /WTe2 nanosheets, such as visible/near-infrared pulsed laser, materials processing, optical sensors, and modulators. PMID:26800122

  3. Sodium recovery vessel

    International Nuclear Information System (INIS)

    Purpose: To enable to efficiently separate and recover sodium or reaction product in the secondly coolant circuit of FBR type nuclear power plant. Constitution: an upper element is disposed above a cyclone in a sodium recovery vessel, to which a gas formed by sodium-water reaction is caused to flow. Sodium and gases formed by sodium-water reaction introduced from a gas inlet of pressure open system pipeways descend downwardly as swirling stream in a cylindrical vessel within the circumferential flow channel along the outer wall of the shround surrounding the cyclone and the inner wall of the cylindrical vessel. In this case, liquid sodium is separated from the gas, falls to the bottom of the cylindrical vessel as an accumulated liquid. The gas stream passes between each of the elements in the upper element to enable separation of sodium or reaction product, as well as separated sodium and reaction product are urged to the outer circumferential side since all of the upper element and the buffer plate are arranged with their outer circumferential being lowered. (Horiuchi, T.)

  4. Visibility in sodium fume

    International Nuclear Information System (INIS)

    The appearance of sodium fume of unknown concentration and the effects of short term exposure on unprotected workers is described. The molecular extinction coefficient of sodium fume is calculated from which light transmission data, and a rapid method for the estimation of the fume concentration is proposed. (author)

  5. Annular sodium flowsensor

    International Nuclear Information System (INIS)

    This paper describes a unique eddy-current type liquid sodium flowsensor, designed as a joint effort between Argonne National Laboratory and Kaman Instrumentation Corp. Test results are included for operation of the flowsensor mounted on a sodium test loop whose configuration simulates the actual operating conditions, except for the magnetic field of the ALIP

  6. Sodium concrete reactions

    International Nuclear Information System (INIS)

    The data from an extensive series of sodium/concrete reaction tests are presented and mechanisms by which the reactions proceed are analyzed. The results indicate water transport and the resulting sodium/water reaction dominate both the chemical energy release and H2 generation. A mechanism which explains the limited penetration of concrete observed in most of these tests is proposed

  7. Tungsten Oxide and Polyaniline Composite Fabricated by Surfactant-Templated Electrodeposition and Its Use in Supercapacitors

    Directory of Open Access Journals (Sweden)

    Benxue Zou

    2014-01-01

    Full Text Available Composite nanostructures of tungsten oxide and polyaniline (PANI were fabricated on carbon electrode by electrocodeposition using sodium dodecylbenzene sulfonate (SDBS as the template. The morphology of the composite can be controlled by changing SDBS surfactant and aniline monomer concentrations in solution. With increasing concentration of aniline in surfactant solution, the morphological change from nanoparticles to nanofibers was observed. The nanostructured WO3/PANI composite exhibited enhanced capacitive charge storage with the specific capacitance of 201 F g−1 at 1.28 mA cm−2 in large potential window of -0.5~ 0.65 V versus SCE compared to the bulk composite film. The capacitance retained about 78% when the sweeping potential rate increased from 10 to 150 mV/s.

  8. Tungsten transport in the plasma edge at ASDEX upgrade

    International Nuclear Information System (INIS)

    The Plasma Facing Components (PFC) will play a crucial role in future deuterium-tritium magnetically confined fusion power plants, since they will be subject to high energy and particle loads, but at the same time have to ensure long lifetimes and a low tritium retention. These requirements will most probably necessitate the use of high-Z materials such as tungsten for the wall materials, since their erosion properties are very benign and, unlike carbon, capture only little tritium. The drawback with high-Z materials is, that they emit strong line radiation in the core plasma, which acts as a powerful energy loss mechanism. Thus, the concentration of these high-Z materials has to be controlled and kept at low levels in order to achieve a burning plasma. Understanding the transport processes in the plasma edge is essential for applying the proper impurity control mechanisms. This control can be exerted either by enhancing the outflux, e.g. by Edge Localized Modes (ELM), since they are known to expel impurities from the main plasma, or by reducing the influx, e.g. minimizing the tungsten erosion or increasing the shielding effect of the Scrape Off Layer (SOL). ASDEX Upgrade (AUG) has been successfully operating with a full tungsten wall for several years now and offers the possibility to investigate these edge transport processes for tungsten. This study focused on the disentanglement of the frequency of type-I ELMs and the main chamber gas injection rate, two parameters which are usually linked in H-mode discharges. Such a separation allowed for the first time the direct assessment of the impact of each parameter on the tungsten concentration. The control of the ELM frequency was performed by adjusting the shape of the plasma, i.e. the upper triangularity. The radial tungsten transport was investigated by implementing a modulated tungsten source. To create this modulated source, the linear dependence of the tungsten erosion rate at the Ion Cyclotron Resonance

  9. Tungsten transport in the plasma edge at ASDEX upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Janzer, Michael Arthur

    2015-04-30

    The Plasma Facing Components (PFC) will play a crucial role in future deuterium-tritium magnetically confined fusion power plants, since they will be subject to high energy and particle loads, but at the same time have to ensure long lifetimes and a low tritium retention. These requirements will most probably necessitate the use of high-Z materials such as tungsten for the wall materials, since their erosion properties are very benign and, unlike carbon, capture only little tritium. The drawback with high-Z materials is, that they emit strong line radiation in the core plasma, which acts as a powerful energy loss mechanism. Thus, the concentration of these high-Z materials has to be controlled and kept at low levels in order to achieve a burning plasma. Understanding the transport processes in the plasma edge is essential for applying the proper impurity control mechanisms. This control can be exerted either by enhancing the outflux, e.g. by Edge Localized Modes (ELM), since they are known to expel impurities from the main plasma, or by reducing the influx, e.g. minimizing the tungsten erosion or increasing the shielding effect of the Scrape Off Layer (SOL). ASDEX Upgrade (AUG) has been successfully operating with a full tungsten wall for several years now and offers the possibility to investigate these edge transport processes for tungsten. This study focused on the disentanglement of the frequency of type-I ELMs and the main chamber gas injection rate, two parameters which are usually linked in H-mode discharges. Such a separation allowed for the first time the direct assessment of the impact of each parameter on the tungsten concentration. The control of the ELM frequency was performed by adjusting the shape of the plasma, i.e. the upper triangularity. The radial tungsten transport was investigated by implementing a modulated tungsten source. To create this modulated source, the linear dependence of the tungsten erosion rate at the Ion Cyclotron Resonance

  10. Extractive separation and spectrophotometric determination of tungsten as ferrocyanide.

    Science.gov (United States)

    Yatirajam, V; Dhamija, S

    1979-04-01

    Tungsten, in amounts ranging from micrograms to milligrams, can be extracted into isoamyl alcohol, as the tungsten(V) ferrocyanide complex obtained by reduction of tungsten(VI) with tin(II) in 4M hydrochloric acid containing ferrocyanide. It can thus be separated from iron, cobalt, chromium, manganese, arsenic, antimony, bismuth, silicon, calcium and copper, their precipitation being prevented by addition of glycerol and, in the case of iron, sulphosalicyclic acid. Molybdenum, vanadium and nickel are not separated from tungsten, however. Tungsten can also be determined spectrophotometrically as tungsten(V) ferrocyanide. The absorbance of the brown complex is measured in aqueous solution or preferably after extraction into isoamyl alcohol. As many alloying elements interfere, they should be separated by the ferrocyanide extraction or other suitable method. Both the separation and the determination methods give satisfactory results with an overall error of not more than 0.5% in the analysis of practical samples containing low or high percentages of tungsten. PMID:18962438

  11. Measurement of uptake and release of tritium by tungsten

    International Nuclear Information System (INIS)

    Tungsten is currently contemplated as plasma facing material for the divertor of future fusion machines. In this paper the uptake of tritium by tungsten and its release behavior have been investigated. Tungsten samples have been annealed at various temperatures and loaded at also different temperatures with deuterium containing 7.2 % tritium at a pressure of 1.2 kPa. A specific system was designed to assess the release of tritiated water and molecular tritium by the samples. Due to the rather low solubility of hydrogen isotopes in tungsten it is particularly important to be aware of the presence of hydrogen traps or thin oxide films. As shown in this work, traps or oxide films may affect the retention capability of tungsten and lead to significantly modified release properties. It became clear that there were capture sites that had different thermal stability and different capture intensity in tungsten after polishing, or oxide films that were grown on the surface of tungsten and had barrier effects

  12. Molecular dynamics simulations of cumulative helium bombardments on tungsten surfaces

    International Nuclear Information System (INIS)

    Molecular dynamics simulations were performed to study the cumulative bombardments of low-energy (60–200 eV) helium atoms on tungsten surfaces. The behaviour of helium and the response of tungsten surface were investigated. The helium incident energy and tungsten temperature play important roles on the formation and growth of helium clusters. The temperature can promote the coalescence of helium clusters and increase the size of the helium clusters. The rupture of the helium clusters has also been observed. During the formation of helium clusters, the interstitial tungsten atoms are produced and evolve into bundles of <1 1 1> crowdions, which would be constrained around the helium clusters for a long time. However, they will finally move onto the top surface along the <1 1 1> direction, which results in stacking the tungsten atoms on the surface. The complex combination effects of the helium clusters and the interstitial atoms result in the growth of the surfaces. Besides, several tungsten atoms were ejected from tungsten surfaces

  13. Las Lunas (Yuncler, Toledo. A Bronze Age hoard with metallic materials from the southern Iberian Meseta

    Directory of Open Access Journals (Sweden)

    Urbina Martínez, Dionisio

    2010-06-01

    Full Text Available Here we present the results of the preliminary study carried out on a new group of metallic materials of the Final Bronze Age, recovered at the end of 2008 in the archaeological excavations at the settlement of Las Lunas (Yuncler, Toledo, Spain. Its geographical situation far away from the main zones of distribution of this type of finds, the singularity of the materials, and the evidence of Atlantic and Mediterranean relations make these materials a remarkable sample for the study of the Final Bronze Age in the centre of the Iberian Peninsula.

    Se exponen los resultados del primer estudio realizado sobre un nuevo conjunto de materiales metálicos del Bronce Final recuperado a finales de 2008 en las excavaciones arqueológicas del yacimiento de Las Lunas (Yuncler, Toledo, España. La localización geográfica del hallazgo, lejos de las principales zonas de dispersión conocidas para este tipo de conjuntos, la singularidad de los objetos que integra, y las relaciones atlánticas y mediterráneas que evidencian sus materiales, lo convierten en un ejemplo destacado para el estudio de este período en el centro de la Península Ibérica.

  14. Thermal conductance at millikelvin temperatures of woven ribbon cable with phosphor-bronze clad superconducting wires

    Science.gov (United States)

    Woodcraft, Adam L.; Ventura, Guglielmo; Martelli, Valentina; Holland, Wayne S.

    2010-08-01

    Woven Nomex® ribbon cables made up with superconducting niobium-titanium wire are used at millikelvin temperatures in many large cryogenic instruments. It is important to know how much heat in transmitted down such cables. However, the conductivity of the materials used is not well known. Another problem is that the wires are normally clad with alloys which exhibit some magnetism. This is a potential problem for instruments employing superconducting detectors. A safe non-magnetic alternative to the usual materials is phosphor-bronze clad niobium-titanium wiring. However, there is little experience with such wires. We have therefore measured the conductance of a ribbon cable made up with these wires. The measured values are in good agreement with our predictions, suggesting that the values we have used to model the cable are sufficiently accurate, and could therefore be used to predict the performance of ribbon cables using other cladding materials, so long as the conductivity of the cladding is reasonably well known. As part of our analysis, we consider the likely variation in thermal conductivity values for C51000 phosphor bronze caused by legitimate variations in composition.

  15. Neutron activation analysis of Lerna ceramics (Greece) at Early Bronze Age: local production and trade exchanges

    International Nuclear Information System (INIS)

    Neutron activation analysis is a powerful tool for determining the provenance of ancient ceramics. A sophisticated analytical system for gamma-ray spectrometry, designed specifically for the chemical analysis of ceramics by thermal neutron activation, was used to determine the concentrations of twenty elements in samples of ancient pottery. The measurements were made relative to the standard pottery of Perlman and Asaro. The purpose of the work was to study the production of fine pottery at the settlement of Lerna, in the Argolid of Greece, during the Early Bronze Age (third millennium BC). About half of the 50 samples analysed formed the major compositional group, which was attributed to Lerna. It included, besides the majority of the samples from the second phase of the Early Bronze Age (Lerna III), several samples from the third phase (Lerna IV); that is, from levels immediately succeeding the great destruction which marks the end of the Lerna III settlement. A small number of objects forms a second group of local origin and includes 4 of the 5 clay sealings sampled. Among the archaeologically unusual objects, several could be attributed to Lerna, while others were characterized as imports

  16. The atmospheric corrosion of quaternary bronzes: An evaluation of the dissolution rate of the alloying elements

    Science.gov (United States)

    Bernardi, E.; Chiavari, C.; Martini, C.; Morselli, L.

    2008-07-01

    A comparative evaluation of the corrosion behaviour of a G85 bronze in acid rain solutions was performed. As weathering technique, a wet dry device was used to simulate a cyclic exposure to stagnant rain. The weathering solutions were a collected natural rain and an artificial solution reproducing the natural rain. The solutions were periodically monitored as concerns pH and metallic ion concentrations. On the aged specimens, surface studies were performed through OM, SEM and Raman analyses. At the end of weathering tests (40 days), weight loss measurements were carried out. The aim of this work was to examine the reproducibility in laboratory of the corrosive conditions determined by a natural acid rain. The final goal of this research is to investigate the dissolution of a quaternary alloy exposed to acid rains. The results showed slightly different corrosion behaviours as a consequence of the exposure to natural or synthetic rain. Concerning the mechanism of corrosion of G85 bronze, the innovative approach adopted in this study allowed one to point out the contribution of each alloying element to the general corrosion. Actually, while Cu and Pb progressively form insoluble corrosion compounds, Zn continuously dissolves, without forming detectable insoluble products. The absence of dissolved tin is remarkable.

  17. Generation of nanoparticles of bronze and brass by laser ablation in liquid

    International Nuclear Information System (INIS)

    Nanoparticles of brass and bronze are generated by ablation of corresponding bulk targets in liquid ethanol. The experiments were performed using three pulsed lasers with different pulse duration: ytterbium fiber laser (80 ns), a Neodymium:YAG laser (10 ps), and femtosecond Ti:sapphire laser (200 fs). The generated nanoparticles (NPs) are characterized by UV–vis absorption spectroscopy, X-ray diffractometry, Raman scattering, and Transmission Electron Microscopy. The size of generated NPs lies in the range 10–25 nm depending on the laser source. The X-ray diffractometry reveals the change of phase composition of brass NPs compared to the initial target in case of ablation with 80 ns laser source, while with 10 ps laser pulses this effect is less pronounced. Brass NPs generated with pico- and femtosecond laser radiation show the plasmon resonance in the vicinity of 560 nm and no plasmon peak for NPs generated with longer laser pulses. Raman analysis shows the presence of Cu2O in generated NPs. The stability of generated NPs of both brass and bronze to oxidation is compared to that of Cu NPs generated in similar experimental conditions.

  18. $Nb_{3}Sn macrostructure, microstructure, and property comparisons for bronze and internal Sn process strands

    CERN Document Server

    Lee, P J; Larbalestier, D C

    2000-01-01

    The variation in irreversibility field, B*(T), with temperature has been measured for Nb/sub 3/Sn superconducting strands manufactured for ITER using vibrating sample and SQUID magnetometers. The high performance strands were developed for both high transport critical current density, J/sub c/, and low hysteresis loss. Despite a wide variety of designs and components, the strands could be split into two distinctive groups, based on the extrapolated irreversibility fields, which lie about 10% lower than the upper critical field. "Bronze-process" strands exhibited consistently higher B*(T) (28 T to 31 T) compared with "internal Sn" process (24 T to 26 T) conductors. The intrinsic critical current density of the superconductor, J/sub c (sc)/, and the specific pinning force of the grain boundaries, Q/sub gb/, were evaluated using the measured J/sub c/, and image analysis of the macro- and micro-structures. A bronze-processed Nb(-Ta)/sub 3 /Sn was found to have a higher J/sub c(sc)/ but lower Q/sub gb/ than Nb/sub...

  19. Comparison of phosphor bronze metal sheet produced by twin roll casting and horizontal continuous casting

    Science.gov (United States)

    Hwang, J. D.; Li, B. J.; Hwang, W. S.; Hu, C. T.

    1998-08-01

    Much effort recently has been expended to study the strip casting process used to produce thin metal strip with a near final thickness. This process eliminates the need for hot rolling, consumes less energy, and offers a feasible method of producing various hard-to-shape alloys. The finer microstructure that results from the high cooling rate used during the casting process enhances mechanical properties. In this study, strips of phosphor bronzes (Cu-Sn-P) metal were produced using a twin roll strip casting process as well as a conventional horizontal continuous casting (HCC) process. The microstructures, macrosegregations, textures, and mechanical properties of the as-cast and as-rolled metal sheet produced by these two methods were examined carefully for comparative purposes. The results indicate that cast strip produced by a twin roll caster exhibit significantly less inverse segregation of tin compared to that produced by the HCC process. The mechanical properties including tensile strength, elongation, and microhardness of the products produced by the twin roll strip casting process are comparable to those of the HCC processed sheet. These properties meet specifications JIS H3110 and ASTM B 103M for commercial phosphor bronze sheet. The texture of the as-rolled sheet from these two processes, as measured from XRD pole figures, were found to be virtually the same, even though a significant difference exists between them in the as-cast condition.

  20. Las lagunas de Ruidera during the Bronze Age: a hierarchical territory

    Directory of Open Access Journals (Sweden)

    Ocaña Carretón, Andrés

    2002-06-01

    Full Text Available This paper shows the first results of a research project that aims to analyse the spatial relationship betwen the natural resources and the settlements in the Upper Guadiana River (South Meseta, Spain. The data obtained will be used to understand the productive system of the communities which lived in this territory during the Copper and Bronze Ages. In particular the settlement pattern during the Bronze Age is analysed in the Nature Reserve of Lagunas de Ruidera. This shows a territorial hierarchical structure and allows us to understand the emergence of social complexity within this territory.

    Este artículo muestra los primeros resultados de un proyecto que tiene por objeto analizar la relación espacial entre los recursos y los asentamientos en el Alto Guadiana como aproximación a los sistemas productivos de las comunidades que habitaron este territorio durante el Calcolítico y la Edad del Bronce. En concreto, se analiza el patrón de asentamiento durante la Edad del Bronce en el Parque Natural de las Lagunas de Ruidera, el cual indica la existencia de una ocupación jerárquica del territorio como reflejo de la existencia de un cierto grado de complejidad social.

  1. A Roman bronze statuette with gilded silver mask from Sardinia: an EDXRF study

    Science.gov (United States)

    Cesareo, Roberto; Brunetti, Antonio; D'Oriano, Rubens; Canu, Alba; Demontis, Gonaria Mattia; Celauro, Angela

    2013-12-01

    A Roman bronze statuette from the 2nd Century BC was recovered from a nuragic sanctuary close to Florinas, in the north of Sardinia. The facial portion of the statuette is covered by a silver mask, partially gilded and attached to the bronze by tin-lead welding. The silver mask was carefully analyzed by portable energy-dispersive X-ray fluorescence (EDXRF), a non-destructive and non-invasive method. The aim of the analysis was to reconstruct the layered structure of the silver gilt mask, and to determine homogeneity and thickness of the gold, silver and lead-tin sheets. This is possible by using the internal ratio of the X-ray lines, i.e. starting from the surface, Au (L α/L β), Ag (K α/K β), Au-L α/Ag-K α and Pb (L α/L β).The results were compared with those obtained with simulated X-ray spectra, obtained both experimentally and by using the Monte Carlo simulation technique.

  2. Shellfish from the Bronze Age Site of Clos des Châtaigniers (Mathieu, Normandy, France

    Directory of Open Access Journals (Sweden)

    Caroline Mougne

    2014-09-01

    Full Text Available This article provides initial results on the use of shellfish by the inhabitants of Clos des Châtaigniers, Normandy (France during the Late Bronze Age. The settlement is located at Mathieu, 10km from the coast. The French National Institute of Preventive Archaeological Research (INRAP conducted excavations on this site in 2010, under the direction of David Giazzon. A semi-circular domestic enclosure from the end of the Late Bronze Age was discovered. The diet of the inhabitants of Mathieu was partly based on mussels, which were found in large quantities. These shells were collected at low tide on a rocky to muddy/rocky shore. They were then transported inland to be eaten fresh or processed. Other marine invertebrates were also present on this site. Some of them were collected with the mussels. In fact, they were mixed with or fixed to this bivalve. Many other small fragments of shells are present on the site and could have come from the stomach contents of fish.

  3. Synthesis and optimization of tungsten and tungsten oxide films produced by laser ablation

    International Nuclear Information System (INIS)

    This work was aimed at achieving an optimal deposition process by pulsed laser ablation (PLA) on large area substrates, using pure tungsten as target. The films were deposited at different: wavelengths (355/532/1064 nm), fluences (1.5, 5 and 10 J/cm2), oxygen pressures (100 and 200 mTorr), substrate temperatures (room temperature, 200, 300, and 400deg. C). The morpho-structural and compositional investigations have been carried out by profilometer, scanning electron microscopy, X-ray diffraction, Rutherford backscattering spectroscopy and Fourier transform infrared spectroscopy. The study has shown that optimal conditions for tungsten deposition on large area surfaces are at 355 nm/ 5 J/cm2. Amorphous, orthorhombic and triclinic phases WO3 films were obtained

  4. Preparation and electrocatalytic activity of tungsten carbide and titania nanocomposite

    International Nuclear Information System (INIS)

    Graphical abstract: The electrocatalytic activity of tungsten carbide and titania nanocomposite is related to the structure, crystal phase and chemical components of the nanocomposite, and is also affected by the property of electrolyte. A synergistic effect exists between tungsten carbide and titania of the composite. Highlights: → Electrocatalytic activity of tungsten carbide and titania nanocomposite with core-shell structure. → Activity is related to the structure, crystal phase and chemical component of the nanocomposite. → The property of electrolyte affects the electrocatalytic activity. → A synergistic effect exists between tungsten carbide and titania of the composite. -- Abstract: Tungsten carbide and titania nanocomposite was prepared by combining a reduced-carbonized approach with a mechanochemical approach. The samples were characterized by X-ray diffraction, transmission electron microscope under scanning mode and X-ray energy dispersion spectrum. The results show that the crystal phases of the samples are composed of anatase, rutile, nonstoichiometry titanium oxide, monotungsten carbide, bitungsten carbide and nonstoichiometry tungsten carbide, and they can be controlled by adjusting the parameters of the reduced-carbonized approach; tungsten carbide particles decorate on the surface of titania support, the diameter of tungsten carbide particle is smaller than 20 nm and that of titania is around 100 nm; the chemical components of the samples are Ti, O, W and C. The electrocatalytic activity of the samples was measured by a cyclic voltammetry with three electrodes. The results indicate that the electrocatalytic activities of the samples are related to their crystal phases and the property of electrolyte in aqueous solution. A synergistic effect between titania and tungsten carbide is reported for the first time.

  5. High Purity Tungsten Spherical Particle Preparation From WC-Co Spent Hard Scrap

    Directory of Open Access Journals (Sweden)

    Han Chulwoong

    2015-06-01

    Full Text Available Tungsten carbide-cobalt hard metal scrap was recycled to obtain high purity spherical tungsten powder by a combined hydrometallurgy and physical metallurgy pathway. Selective leaching of tungsten element from hard metal scrap occurs at solid / liquid interface and therefore enlargement of effective surface area is advantageous. Linear oxidation behavior of Tungsten carbide-cobalt and the oxidized scrap is friable to be pulverized by milling process. In this regard, isothermally oxidized Tungsten carbide-cobalt hard metal scrap was mechanically broken into particles and then tungsten trioxide particle was recovered by hydrometallurgical method. Recovered tungsten trioxide was reduced to tungsten particle in a hydrogen environment. After that, tungsten particle was melted and solidified to make a spherical one by RF (Ratio Frequency thermal plasma process. Well spherical tungsten micro-particle was successfully obtained from spent scrap. In addition to the morphological change, thermal plasma process showed an advantage for the purification of feedstock particle.

  6. Investigation on corrosion stratigraphy and morphology in some Iron Age bronze alloys vessels by OM, XRD and SEM-EDS methods

    Science.gov (United States)

    Oudbashi, Omid; Hasanpour, Ata; Davami, Parviz

    2016-04-01

    The recently study of the corrosion in some bronze artefacts from the Sangtarashan Iron Age site, western Iran, was established to identify corrosion morphology and mechanism in these objects. The corrosion layers in 22 samples were studied by optical microscopy, scanning electron microscopy-energy-dispersive X-ray spectroscopy and X-ray diffraction methods. The results showed that a thin corrosion crust has formed on the surface of bronzes with a triple-layer structure, including two internal and one external corrosion layers. The formation of these layers is due to copper leaching from the bronze surface. The internal corrosion part has been a compact, tin-rich corrosion/oxidation product (noble patina) with some evidences from original metallurgical aspects of the bronze as well as a very thin layer beneath the tin-rich layer. External corrosion products have been identified as basic copper carbonates, malachite and azurite. Based on the results, the corrosion morphology in the Sangtarashan Iron Age bronzes is due to long-term burial in an appropriate environment in a moderately corrosive soil. Although it is the first time to investigate Iron Age bronzes from Iran, this corrosion morphology is partially similar to type I corrosion morphology observed in archaeological bronze objects; nevertheless, some deviations are visible in comparison with previously established patterns.

  7. Determination of concentrations of minor and micro elements in ancient bronze drums artifacts samples by KO-standardization method of neutron activation analysis

    International Nuclear Information System (INIS)

    The study aims to get a lot information about manufacturers of ancient bronze artifacts and ancient civilization. By KO-standardization method of neutron activation analysis developed in the Nuclear Research Institute, the concentrations of Au, Ag, As, Zn, Sb, Sn elements in ancient bronze alloy samples of 99 bronze artifacts from many excavated archaeological sites at the provinces in Vietnam were determined with uncertainties about ±10%. These elemental concentrations have been utilized in a statistical analysis procedure in order to determine similarities and correlation between the various samples. Th abnormal high of concentrations of noble metals as Au, Ag in ancient bronze indicates that the ancient metallurgists had been interested in role of these metals on sound quality of bronze artifacts. Especially, the concentrations of As in many samples are very high even at about 10%. This gives an evidence that in ancient time the humankind could use bronze As alloy in order to improve quality when they had produced bronze artifacts. (author)

  8. An effective approach to synthesize monolayer tungsten disulphide crystals using tungsten halide precursor

    International Nuclear Information System (INIS)

    The synthesis of large-area monolayer tungsten disulphide (WS2) single crystal is critical for realistic application in electronic and optical devices. Here, we demonstrate an effective approach to synthesize monolayer WS2 crystals using tungsten hexachloride (WCl6) as a solid precursor in atmospheric chemical vapor deposition process. In this technique, 0.05M solution of WCl6 in ethanol was drop-casted on SiO2/Si substrate to create an even distribution of the precursor, which was reduced and sulfurized at 750 °C in Ar atmosphere. We observed growth of triangular, star-shaped, as well as dendritic WS2 crystals on the substrate. The crystal geometry evolves with the shape and size of the nuclei as observed from the dendritic structures. These results show that controlling the initial nucleation and growth process, large WS2 single crystalline monolayer can be grown using the WCl6 precursor. Our finding shows an easier and effective approach to grow WS2 monolayer using tungsten halide solution-casting, rather than evaporating the precursor for gas phase reaction

  9. Neutron irradiation effects on the microstructural development of tungsten and tungsten alloys

    Science.gov (United States)

    Hasegawa, Akira; Fukuda, Makoto; Yabuuchi, Kiyohiro; Nogami, Shuhei

    2016-04-01

    Data on the microstructural development of tungsten (W) and tungsten rhenium (Re) alloys were obtained after neutron irradiation at 400-800 °C in the Japan Materials Testing Reactor (JMTR), the experimental fast test reactor Joyo, and the High Flux Isotope Reactor (HFIR) for irradiation damage levels in the range of 0.09-1.54 displacement per atom (dpa). Microstructural observations showed that a small amount of Re (3-5%) in W-Re alloys is effective in suppressing void formation. In W-Re alloys with Re concentrations greater than 10%, acicular precipitates are the primary structural defects. In the HFIR-irradiated specimen, in which a large amount of Re was expected to be produced by the nuclear transmutation of W to Re because of the reactor's high thermal neutron flux, voids were not observed even in pure W. The synergistic effects of displacement damage and solid transmutation elements on microstructural development are discussed, and the microstructural development of tungsten materials utilized in fusion reactors is predicted.

  10. An effective approach to synthesize monolayer tungsten disulphide crystals using tungsten halide precursor

    Energy Technology Data Exchange (ETDEWEB)

    Thangaraja, Amutha; Shinde, Sachin M.; Kalita, Golap, E-mail: kalita.golap@nitech.ac.jp; Tanemura, Masaki [Department of Frontier Materials, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan)

    2016-02-01

    The synthesis of large-area monolayer tungsten disulphide (WS{sub 2}) single crystal is critical for realistic application in electronic and optical devices. Here, we demonstrate an effective approach to synthesize monolayer WS{sub 2} crystals using tungsten hexachloride (WCl{sub 6}) as a solid precursor in atmospheric chemical vapor deposition process. In this technique, 0.05M solution of WCl{sub 6} in ethanol was drop-casted on SiO{sub 2}/Si substrate to create an even distribution of the precursor, which was reduced and sulfurized at 750 °C in Ar atmosphere. We observed growth of triangular, star-shaped, as well as dendritic WS{sub 2} crystals on the substrate. The crystal geometry evolves with the shape and size of the nuclei as observed from the dendritic structures. These results show that controlling the initial nucleation and growth process, large WS{sub 2} single crystalline monolayer can be grown using the WCl{sub 6} precursor. Our finding shows an easier and effective approach to grow WS{sub 2} monolayer using tungsten halide solution-casting, rather than evaporating the precursor for gas phase reaction.

  11. An effective approach to synthesize monolayer tungsten disulphide crystals using tungsten halide precursor

    Science.gov (United States)

    Thangaraja, Amutha; Shinde, Sachin M.; Kalita, Golap; Tanemura, Masaki

    2016-02-01

    The synthesis of large-area monolayer tungsten disulphide (WS2) single crystal is critical for realistic application in electronic and optical devices. Here, we demonstrate an effective approach to synthesize monolayer WS2 crystals using tungsten hexachloride (WCl6) as a solid precursor in atmospheric chemical vapor deposition process. In this technique, 0.05M solution of WCl6 in ethanol was drop-casted on SiO2/Si substrate to create an even distribution of the precursor, which was reduced and sulfurized at 750 °C in Ar atmosphere. We observed growth of triangular, star-shaped, as well as dendritic WS2 crystals on the substrate. The crystal geometry evolves with the shape and size of the nuclei as observed from the dendritic structures. These results show that controlling the initial nucleation and growth process, large WS2 single crystalline monolayer can be grown using the WCl6 precursor. Our finding shows an easier and effective approach to grow WS2 monolayer using tungsten halide solution-casting, rather than evaporating the precursor for gas phase reaction.

  12. Raman study of thermochromic phase transition in tungsten trioxide nanowires

    Science.gov (United States)

    Lu, Dong Yu; Chen, Jian; Chen, Huan Jun; Gong, Li; Deng, Shao Zhi; Xu, Ning Sheng; Liu, Yu Long

    2007-01-01

    Tungsten trioxide (WO3) nanowires were synthesized by thermal evaporation of tungsten powder in two steps: tungsten suboxide (WO3-x) nanowires were synthesized, and then oxidized in O2 ambient and transformed into WO3 nanowires. Raman spectroscopy was applied to study the thermochromic phase transition of one-dimensional WO3 nanowires. From the temperature dependence of the characteristic mode at 33cm-1 in WO3, the phase transition temperature was determined. It was found that the phase transition of WO3 nanowires was reversible and the phase transition temperatures were even lower than that of WO3 nanopowder.

  13. Blister formation on tungsten damaged by high energy particle irradiation

    International Nuclear Information System (INIS)

    In order to investigate the effect of radiation damage on hydrogen behavior in tungsten, tungsten samples with radiation damage of up to 3.5 dpa were irradiated by a mixed hydrogen-carbon ion beam. The radiation damage was produced with 700 keV negative hydrogen ion beam irradiation. The number density of blisters produced by the mixed ion beam irradiation decreased with increasing radiation damage. This was especially observed for blisters with diameters of 20 μm or less. This result showed that radiation damage produced by high-energy particle irradiation suppresses blister formation on tungsten surfaces

  14. Mechanisms of selectivity loss during tungsten CVD (chemical vapor deposition)

    Energy Technology Data Exchange (ETDEWEB)

    Creighton, J.R.

    1990-01-01

    The tungsten subfluoride mechanism as well as other proposed mechanisms of selectivity loss are reviewed. To further demonstrate the viability of the tungsten subfluoride mechanism, we have extended the measurement of the tungsten subfluoride production rate down to 450{degree}C. We also report results from some preliminary experiments designed to identify the selectivity loss mechanism when elemental silicon is available for reaction. Comments regarding the origins of the insulator effect and selectivity loss for silane reduction are offered. 23 refs., 2 figs.

  15. TEM characterization of the microstructure of a tungsten heavy alloy

    Energy Technology Data Exchange (ETDEWEB)

    Fortuna, E.; Zielinski, W.; Sikorski, K.; Kurzydlowski, K.J

    2003-08-28

    The aim of this work was a transmission electron microscopy (TEM) study of the microstructure of a tungsten heavy alloy (WHA). Due to the profound differences in hardness of the tungsten particles and the Ni-Fe-W matrix a special TEM specimen preparation method had to be employed. Despite the presence of some artifacts the investigations gave the microstructure details of as-sintered and annealed cold-rolled specimens. It was found that the WHA annealed after cold rolling reveals a refinement of the microstructure of some tungsten particles and of the matrix in the areas close to the particles.

  16. TEM characterization of the microstructure of a tungsten heavy alloy

    International Nuclear Information System (INIS)

    The aim of this work was a transmission electron microscopy (TEM) study of the microstructure of a tungsten heavy alloy (WHA). Due to the profound differences in hardness of the tungsten particles and the Ni-Fe-W matrix a special TEM specimen preparation method had to be employed. Despite the presence of some artifacts the investigations gave the microstructure details of as-sintered and annealed cold-rolled specimens. It was found that the WHA annealed after cold rolling reveals a refinement of the microstructure of some tungsten particles and of the matrix in the areas close to the particles

  17. Preparation of nanocomposite thoriated tungsten cathode by swaging technique

    Institute of Scientific and Technical Information of China (English)

    王发展; 诸葛飞; 张晖; 丁秉钧

    2002-01-01

    By using the high energy ball milling method,the nanosized ThO2 powders were obtained.Through mixing powders,sintering and hot swaging processing,a nanocomposite thoriated tungsten cathode was fabricated.The relative density of the nanocomposite material is near 100%.The microstructure of nanocomposite cathode is quite different from that of conventional thoriated tungsten cathode.Most of thoria particles are less than 100 nm in diameter,and distribute on the boundaries of tungsten grains.The nanocomposite cathode shows a much lower arc starting field than that of conventional cathode,which will improve the performance of the cathode significantly.

  18. Chemically assisted ion beam etching of polycrystalline and (100)tungsten

    Science.gov (United States)

    Garner, Charles

    1987-01-01

    A chemically assisted ion-beam etching technique is described which employs an ion beam from an electron-bombardment ion source and a directed flux of ClF3 neutrals. This technique enables the etching of tungsten foils and films in excess of 40 microns thick with good anisotropy and pattern definition over areas of 30 sq mm, and with a high degree of selectivity. (100) tungsten foils etched with this process exhibit preferred-orientation etching, while polycrystalline tungsten films exhibit high etch rates. This technique can be used to pattern the dispenser cathode surfaces serving as electron emitters in traveling-wave tubes to a controlled porosity.

  19. METHOD FOR REMOVING SODIUM OXIDE FROM LIQUID SODIUM

    Science.gov (United States)

    Bruggeman, W.H.; Voorhees, B.G.

    1957-12-01

    A method is described for removing sodium oxide from a fluent stream of liquid sodium by coldtrapping the sodium oxide. Apparatus utilizing this method is disclosed in United States Patent No. 2,745,552. Sodium will remain in a molten state at temperatures below that at which sodium oxide will crystallize out and form solid deposits, therefore, the contaminated stream of sodium is cooled to a temperature at which the solubility of sodium oxide in sodium is substantially decreased. Thereafter the stream of sodium is passed through a bed of stainless steel wool maintained at a temperature below that of the stream. The stream is kept in contact with the wool until the sodium oxide is removed by crystal growth on the wool, then the stream is reheated and returned to the system. This method is useful in purifying reactor coolants where the sodium oxide would otherwise deposit out on the walls and eventually plug the coolant tubes.

  20. 48 CFR 252.216-7000 - Economic price adjustment-basic steel, aluminum, brass, bronze, or copper mill products.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 3 2010-10-01 2010-10-01 false Economic price adjustment... SOLICITATION PROVISIONS AND CONTRACT CLAUSES Text of Provisions And Clauses 252.216-7000 Economic price...), use the following clause: Economic Price Adjustment—Basic Steel, Aluminum, Brass, Bronze, or...