WorldWideScience

Sample records for metallic powders hyperfine

  1. Spherical rhenium metal powder

    International Nuclear Information System (INIS)

    Leonhardt, T.; Moore, N.; Hamister, M.

    2001-01-01

    The development of a high-density, spherical rhenium powder (SReP) possessing excellent flow characteristics has enabled the use of advanced processing techniques for the manufacture of rhenium components. The techniques that were investigated were vacuum plasma spraying (VPS), direct-hot isostatic pressing (D-HIP), and various other traditional powder metallurgy processing methods of forming rhenium powder into near-net shaped components. The principal disadvantages of standard rhenium metal powder (RMP) for advanced consolidation applications include: poor flow characteristics; high oxygen content; and low and varying packing densities. SReP will lower costs, reduce processing times, and improve yields when manufacturing powder metallurgy rhenium components. The results of the powder characterization of spherical rhenium powder and the consolidation of the SReP are further discussed. (author)

  2. Hyperfine interactions and structural features of Fe–44Co–6Mo (wt.%) nanostructured powders

    International Nuclear Information System (INIS)

    Moumeni, Hayet; Nemamcha, Abderrafik; Alleg, Safia; Grenèche, Jean Marc

    2013-01-01

    Nanocrystalline Fe–44Co–6Mo (wt.%) powders have been prepared by high-energy ball milling from elemental Fe, Co and Mo pure powders in a P7 planetary ball mill. The obtained powders were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Mössbauer spectrometry techniques. The influence of milling process and Mo substitution for Co in equiatomic FeCo have been examined in order to study structural evolution and formation mechanism of nanostructured Fe(CoMo) solid solution. XRD results show the formation of a BCC Fe(CoMo) solid solution (a = 0.2874 nm) where unmixed nanocrystalline Mo with a BCC structure is embedded. Disordered Fe(CoMo) solid solution is characterized by a broad hyperfine magnetic field distribution with two regions centered at B 1 = 35.0 T and B 2 = 30.7 T, respectively, attributed to disordered Fe(Co) solid solution and CoMo enriched environments. Prolonged milling and Mo addition cause the decrease of average hyperfine magnetic field while the average isomer shift remains nearly constant. - Highlights: ► BCC nanostructured Fe(CoMo) solid solution is prepared by milling of Fe, Co and Mo. ► Formation mechanism: Co diffusion into Fe lattice and Mo dissolution in Fe(Co). ► Crystallite size of Fe(CoMo) solid solution reaches 11 nm after 24 h of milling. ► Mössbauer analysis reveals 3 components: high field, enriched Co and low field

  3. Hyperfine interactions and structural features of Fe–44Co–6Mo (wt.%) nanostructured powders

    Energy Technology Data Exchange (ETDEWEB)

    Moumeni, Hayet, E-mail: hmoumeni@yahoo.fr [Laboratoire de Chimie Computationnelle et Nanostructures, Département des Sciences de la Matière, Faculté des Mathématiques et de l' Informatique et des Sciences de la Matière, Université 08 Mai 1945 - Guelma, B.P. 401, Guelma 24000 (Algeria); Nemamcha, Abderrafik [Laboratoire d' Analyses Industrielles et Génie des Matériaux, Faculté des Sciences et de la Technologie, Université 08 Mai 1945 - Guelma, B.P. 401, Guelma 24000 (Algeria); Alleg, Safia [Laboratoire de Magnétisme et de Spectroscopie des Solides, Département de Physique, Faculté des Sciences, Université de Annaba, B.P. 12, Annaba 23000 (Algeria); Grenèche, Jean Marc [Laboratoire de Physique de l' Etat Condensé, UMR CNRS 6087, Institut de Recherche en Ingénierie Moléculaire et Matériaux Fonctionnels IRIM2F, FR CNRS 2575, Université du Maine, 72085 Le Mans Cedex 9 (France)

    2013-02-15

    Nanocrystalline Fe–44Co–6Mo (wt.%) powders have been prepared by high-energy ball milling from elemental Fe, Co and Mo pure powders in a P7 planetary ball mill. The obtained powders were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Mössbauer spectrometry techniques. The influence of milling process and Mo substitution for Co in equiatomic FeCo have been examined in order to study structural evolution and formation mechanism of nanostructured Fe(CoMo) solid solution. XRD results show the formation of a BCC Fe(CoMo) solid solution (a = 0.2874 nm) where unmixed nanocrystalline Mo with a BCC structure is embedded. Disordered Fe(CoMo) solid solution is characterized by a broad hyperfine magnetic field distribution with two regions centered at B{sub 1} = 35.0 T and B{sub 2} = 30.7 T, respectively, attributed to disordered Fe(Co) solid solution and CoMo enriched environments. Prolonged milling and Mo addition cause the decrease of average hyperfine magnetic field while the average isomer shift remains nearly constant. - Highlights: ► BCC nanostructured Fe(CoMo) solid solution is prepared by milling of Fe, Co and Mo. ► Formation mechanism: Co diffusion into Fe lattice and Mo dissolution in Fe(Co). ► Crystallite size of Fe(CoMo) solid solution reaches 11 nm after 24 h of milling. ► Mössbauer analysis reveals 3 components: high field, enriched Co and low field.

  4. Synthesis of Uranium nitride powders using metal uranium powders

    International Nuclear Information System (INIS)

    Yang, Jae Ho; Kim, Dong Joo; Oh, Jang Soo; Rhee, Young Woo; Kim, Jong Hun; Kim, Keon Sik

    2012-01-01

    Uranium nitride (UN) is a potential fuel material for advanced nuclear reactors because of their high fuel density, high thermal conductivity, high melting temperature, and considerable breeding capability in LWRs. Uranium nitride powders can be fabricated by a carbothermic reduction of the oxide powders, or the nitriding of metal uranium. The carbothermic reduction has an advantage in the production of fine powders. However it has many drawbacks such as an inevitable engagement of impurities, process burden, and difficulties in reusing of expensive N 15 gas. Manufacturing concerns issued in the carbothermic reduction process can be solved by changing the starting materials from oxide powder to metals. However, in nitriding process of metal, it is difficult to obtain fine nitride powders because metal uranium is usually fabricated in the form of bulk ingots. In this study, a simple reaction method was tested to fabricate uranium nitride powders directly from uranium metal powders. We fabricated uranium metal spherical powder and flake using a centrifugal atomization method. The nitride powders were obtained by thermal treating those metal particles under nitrogen containing gas. We investigated the phase and morphology evolutions of powders during the nitriding process. A phase analysis of nitride powders was also a part of the present work

  5. Hyperfine spectroscopic study of the metal-insulator transition in V2O3

    Science.gov (United States)

    Forker, M.; Saitovitch, H.; de Jesus Silva, P. R.

    1983-12-01

    The metal-insulator (M-I) transition in vanadium sesquioxide V2O3 has been investigated by time differential perturbed angular correlation measurements of the electric fieldgradient (EFG) and the magnetic hyperfine field at dilute111Cd impurities. The EFG undergoes a first-order change at the M-I transition at Tt=160 K, but does not reflect the high temperature resistivity anomaly. The increase of the EFG with temperature in the metallic phase can be attributed to thermal variations of the oxygen sublattice. The temperature dependence of the magnetic hyperfine field in the insulating phase follows a Brioullin function with a saturation value of Hhf(O)=15 KOe and an extrapolated Neel temperature, which, depending on the impurity concentration, varies between 188 and 230 K.

  6. Contribution to the theoretical study of metallic systems containing rare earths: hyperfine interactions and exchange coupling

    International Nuclear Information System (INIS)

    Troper, A.

    1978-01-01

    A theoretical study involving rare earth impurities, which were embedded in transition metals (s-p or noble), from the point of view of the hyperfine interactions is presented. A model was created to describe a d-resonance (Anderson-Moriya) acting on a s-p conduction band which was strongly perturbed by a slater-koster potential, used to describe the rare earths which were diluted in matrices of transition elements. (author)

  7. Safety consideration when handling metal powders

    CSIR Research Space (South Africa)

    Benson, JM

    2012-03-01

    Full Text Available Metal powder compaction offers unique advantages in the manufacture of net-shape components using techniques such as laser sintering, conventional press and sintering, metal injection moulding, direct rolling, direct forging, and hot isostatic...

  8. Evolution of structure, microstructure and hyperfine properties of nanocrystalline Fe50Co50 powders prepared by mechanical alloying

    International Nuclear Information System (INIS)

    Akkouche, K.; Guittoum, A.; Boukherroub, N.; Souami, N.

    2011-01-01

    Nanostructured Fe 50 Co 50 powders were prepared by mechanical alloying of Fe and Co elements in a vario-planetary high-energy ball mill. The structural properties, morphology changes and local iron environment variations were investigated as a function of milling time (in the 0-200 h range) by means of X-ray diffraction, scanning electron microscopy (SEM), energy dispersive X-ray analysis and 57 Fe Moessbauer spectroscopy. The complete formation of bcc Fe 50 Co 50 solid solution is observed after 100 h milling. As the milling time increases from 0 to 200 h, the lattice parameter decreases from 0.28655 nm for pure Fe to 0.28523 nm, the grain size decreases from 150 to 14 nm, while the meal level of strain increases from 0.0069% to 1.36%. The powder particle morphology at different stages of formation was observed by SEM. The parameters derived from the Moessbauer spectra confirm the beginning of the formation of Fe 50 Co 50 phase at 43 h of milling. After 200 h of milling the average hyperfine magnetic field of 35 T suggests that a disordered bcc Fe-Co solid solution is formed. - Highlights: → Nanostructured Fe 50 Co 50 powders were successfully prepared by mechanical alloying process. → Final average grain size value achieved after 200 h of milling was 14 nm. → For the longest milling time the majority of particle grains observed by SEM exhibits a round shape with small diameter.

  9. Method for preparing metal powder, device for preparing metal powder, method for processing spent nuclear fuel

    Science.gov (United States)

    Park, Jong-Hee [Clarendon Hills, IL

    2011-11-29

    A method for producing metal powder is provided the comprising supplying a molten bath containing a reducing agent, contacting a metal oxide with the molten bath for a time and at a temperature sufficient to reduce the metal in the metal oxide to elemental metal and produce free oxygen; and isolating the elemental metal from the molten bath.

  10. Progress in Titanium Metal Powder Injection Molding

    OpenAIRE

    German, Randall M.

    2013-01-01

    Metal powder injection molding is a shaping technology that has achieved solid scientific underpinnings. It is from this science base that recent progress has occurred in titanium powder injection molding. Much of the progress awaited development of the required particles with specific characteristics of particle size, particle shape, and purity. The production of titanium components by injection molding is stabilized by a good understanding of how each process variable impacts density and im...

  11. Isostatic pressing of metal powders

    International Nuclear Information System (INIS)

    Cytermann, R.; Auguin, B.; Defresne, A.; Gilles, P.

    1975-01-01

    The process of powders compaction is of great technical importance for the attainment of sintered bodies of high density and strength, or of bodies with controlled porosity. For this purpose, different carbonyl nickel and carbonyl iron powders were isostatically compacted at pressures from 50 to 1300 MN/m 2 (0.5-13kbars). The density of compacts was determined by stereology (quantitative microscopic analysis) and weighing. The two methods were found to be in very good agreement and permit to correlate the density of the compact with the applied pressure, while differentiating the stages of compaction (particle rearrangement, local and homogeneous plastic flow) and showing off the influence of material properties (particle size distribution, particle sphape, ability of the particles to deform, yield stress required for deformation, etc...) The way from one stage to the other was corroborated by scanning electron microscope observation and X-rays diffraction. Electrical resistance and tensile strength measurements were also carried out and permitted to correlate these parameters and the applied pressure [fr

  12. Laser Processing Technology using Metal Powders

    International Nuclear Information System (INIS)

    Jang, Jeong-Hwan; Moon, Young-Hoon

    2012-01-01

    The purpose of this paper is to review the state of laser processing technology using metal powders. In recent years, a series of research and development efforts have been undertaken worldwide to develop laser processing technologies to fabricate metal-based parts. Layered manufacturing by the laser melting process is gaining ground for use in manufacturing rapid prototypes (RP), tools (RT) and functional end products. Selective laser sintering / melting (SLS/SLM) is one of the most rapidly growing rapid prototyping techniques. This is mainly due to the processes's suitability for almost any materials, including polymers, metals, ceramics and many types of composites. The interaction between the laser beam and the powder material used in the laser melting process is one of the dominant phenomena defining feasibility and quality. In the case of SLS, the powder is not fully melted during laser scanning, therefore the SLS-processed parts are not fully dense and have relatively low strength. To overcome this disadvantage, SLM and laser cladding (LC) processes have been used to enable full melting of the powder. Further studies on the laser processing technology will be continued due to the many potential applications that the technology offers.

  13. Hyperfine spectroscopic study of the metal-insulator transition in V/sub 2/O/sub 3/

    Energy Technology Data Exchange (ETDEWEB)

    Forker, M.; Saitovitch, H.; de Jesus Silva, P.R. (Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro)

    1983-12-01

    The metal-insulator (M-I) transition in vanadium sesquioxide V/sub 2/O/sub 3/ has been investigated by time differential perturbed angular correlation measurements of the electric field gradient (EFG) and the magnetic hyperfine field at dilute /sup 111/Cd impurities. The EFG undergoes a first-order change at the M-I transition at 160 K, but does not reflect the high temperature resistivity anomaly. The increase of the EFG with temperature in the metallic phase can be attributed to thermal variations of the oxygen sublattice. The temperature dependence of the magnetic hyperfine field in the insulating phase follows a Brioullin function with a saturation value of 15 KOe and an extrapolated Neel temperature, which, depending on the impurity concentration, varies between 188 and 230 K.

  14. Orientation of the magnetic hyperfine field at 111Cd in HCP Gd metal studied by perturbed angular correlations

    International Nuclear Information System (INIS)

    Presa, P. de la; Forker, M.; Cavalcante, L.Th.

    2004-01-01

    The orientation of the magnetic hyperfine field B hf at 111 Cd in gadolinium metal relative to the hexagonal symmetry axis of the host has been investigated by perturbed angular correlation spectroscopy. Its temperature dependence agrees with the results of μSR and neutron diffraction measurements of the orientation of the Gd magnetic moment, indicating that the Gd anisotropy constants are not greatly altered by the impurity substitution

  15. Progress in Titanium Metal Powder Injection Molding.

    Science.gov (United States)

    German, Randall M

    2013-08-20

    Metal powder injection molding is a shaping technology that has achieved solid scientific underpinnings. It is from this science base that recent progress has occurred in titanium powder injection molding. Much of the progress awaited development of the required particles with specific characteristics of particle size, particle shape, and purity. The production of titanium components by injection molding is stabilized by a good understanding of how each process variable impacts density and impurity level. As summarized here, recent research has isolated the four critical success factors in titanium metal powder injection molding (Ti-MIM) that must be simultaneously satisfied-density, purity, alloying, and microstructure. The critical role of density and impurities, and the inability to remove impurities with sintering, compels attention to starting Ti-MIM with high quality alloy powders. This article addresses the four critical success factors to rationalize Ti-MIM processing conditions to the requirements for demanding applications in aerospace and medical fields. Based on extensive research, a baseline process is identified and reported here with attention to linking mechanical properties to the four critical success factors.

  16. Progress in Titanium Metal Powder Injection Molding

    Directory of Open Access Journals (Sweden)

    Randall M. German

    2013-08-01

    Full Text Available Metal powder injection molding is a shaping technology that has achieved solid scientific underpinnings. It is from this science base that recent progress has occurred in titanium powder injection molding. Much of the progress awaited development of the required particles with specific characteristics of particle size, particle shape, and purity. The production of titanium components by injection molding is stabilized by a good understanding of how each process variable impacts density and impurity level. As summarized here, recent research has isolated the four critical success factors in titanium metal powder injection molding (Ti-MIM that must be simultaneously satisfied—density, purity, alloying, and microstructure. The critical role of density and impurities, and the inability to remove impurities with sintering, compels attention to starting Ti-MIM with high quality alloy powders. This article addresses the four critical success factors to rationalize Ti-MIM processing conditions to the requirements for demanding applications in aerospace and medical fields. Based on extensive research, a baseline process is identified and reported here with attention to linking mechanical properties to the four critical success factors.

  17. PREPARATION OF METAL OXIDE POWDERS FROM METAL LOADED VERSATIC ACID

    OpenAIRE

    KAKIHATA, Takayuki; USAMI, Kensuke; YAMAMOTO, Hideki; SHIBATA, Junji

    1998-01-01

    A production process for metal oxide powders was developed using a solvent extraction method. Versatic Acid 10 and D2EHPA solutions containing copper, zinc and nickel were used for a precipitation-stripping process, where oxalic acid was added to the solution as a precipitation reagent.Copper, zinc and nickel oxalates were easily formed in an aqueous phase, and 99.9% of precipitation was obtained for each metal during this process. These metal oxalates were easily converted to metal oxides by...

  18. Joining of parts via magnetic heating of metal aluminum powders

    Science.gov (United States)

    Baker, Ian

    2013-05-21

    A method of joining at least two parts includes steps of dispersing a joining material comprising a multi-phase magnetic metal-aluminum powder at an interface between the at least two parts to be joined and applying an alternating magnetic field (AMF). The AMF has a magnetic field strength and frequency suitable for inducing magnetic hysteresis losses in the metal-aluminum powder and is applied for a period that raises temperature of the metal-aluminum powder to an exothermic transformation temperature. At the exothermic transformation temperature, the metal-aluminum powder melts and resolidifies as a metal aluminide solid having a non-magnetic configuration.

  19. Process for the preparation of fine grain metal carbide powders

    International Nuclear Information System (INIS)

    Gortsema, F.P.

    1976-01-01

    Fine grain metal carbide powders are conveniently prepared from the corresponding metal oxide by heating in an atmosphere of methane in hydrogen. Sintered articles having a density approaching the theoretical density of the metal carbide itself can be fabricated from the powders by cold pressing, hot pressing or other techniques. 8 claims, no drawings

  20. Improving the calculation of electron paramagnetic resonance hyperfine coupling tensors for d-block metals

    DEFF Research Database (Denmark)

    Hedegård, Erik Donovan; Kongsted, Jacob; Sauer, Stephan P. A.

    2012-01-01

    and obtained a set of basis functions for the elements Sc–Zn, which were saturated with respect to both the Fermi contact and spin-dipolar components of the hyperfine coupling tensor [Hedeg°ard et al., J. Chem. Theory Comput., 2011, 7, pp. 4077-4087]. Furthermore, a contraction scheme was proposed leading...

  1. Bimodal metal micro-nanopowders for powder injection molding

    Science.gov (United States)

    Pervikov, Aleksandr; Rodkevich, Nikolay; Glazkova, Elena; Lerner, Marat

    2017-12-01

    The paper studies a bimodal metal powder composition designed to prepare feedstock for powder injection molding, as well as microstructure and porosity of sintered pats. Two kinds of metal powder compositions are used, in particular, a mixture of micro- and nanopowders and a bimodal powder prepared with dispersion of steel wire. The feedstock is prepared by mixing a bimodal metal powder composition with acetylacetone and paraffin wax. The microstructure of the debound parts is observed by scanning electron microscopy. The sintered parts are characterized by density measurements and metallographic analysis. The technique of the metal powder composition proves to affect the characteristics of sintered parts. Nanoparticles are shown in the interstitial spaces among the microparticles upon mixing micro- and nanopowders, but the regular distribution of nanoparticles on the surface of microparticles is observed in the bimodal powder providing the reduction of the porosity of sintered parts and increasing the density to the proper density of steel.

  2. Metallization of uranium oxide powders by lithium reduction

    International Nuclear Information System (INIS)

    Kim, I. S.; Seo, J. S.; Oh, S. C.; Hong, S. S.; Lee, W. K.

    2002-01-01

    Laboratory scale experiments on the reduction of uranium oxide powders into metal by lithium were performed in order to determine the equipment setup and optimum operation conditions. The method of filtration using the porous magnesia filter was introduced to recover uranium metal powders produced. Based on the laboratory scale experimental results, mock-up scale (20 kg U/batch) metallizer was designed and made. The applicability to the metallization process was estimated with respect to the thermal stability of the porous magnesia filter in the high temperature molten salt, the filtration of the fine uranium metal powders, and the operability of the equipment

  3. The effect of oxygen vacancies on the hyperfine properties of metal-doped SnO2

    Science.gov (United States)

    Aragón, F. H.; Villegas-Lelovsky, L.; Martins, J. B. L.; Coaquira, J. A. H.; Cohen, R.; Nagamine, L. C. C. M.; Morais, P. C.

    2017-03-01

    We have performed a Mössbauer investigation of oxygen-vacancy formation on a doped substitutional solution of Sn1-y M y O2 (M  =  Al, Fe, Ce and Er) nanoparticles. Experimental results were assessed from Mössbauer spectroscopy data, which suggest the rise of the oxygen-vacancy population while increasing the content of dopant ions (M). Likewise, we have analyzed the dependence of the structural, electronic and hyperfine properties on the oxygen-vacancy concentration through first-principles calculations of the SnO2-x (where x varies from 0 to 0.25) system. The results obtained from the isomer shift and quadrupole splitting indicate a significant dependence of the hyperfine properties on the number of oxygen vacancies. Moreover, after structural optimization of the Sn16O32-Vo supercell (where Vo is the number of oxygen vacancies) we found an increase of the unit-cell volume with the increase of Vo, while the bulk modulus showed a linear decrease with Vo. Indeed, our results corroborate the experimental findings for pure and transition-metal-doped SnO2 systems for which the presence of the oxygen vacancy plays a key role.

  4. Production of nanocrystalline metal powders via combustion reaction synthesis

    Science.gov (United States)

    Frye, John G.; Weil, Kenneth Scott; Lavender, Curt A.; Kim, Jin Yong

    2017-10-31

    Nanocrystalline metal powders comprising tungsten, molybdenum, rhenium and/or niobium can be synthesized using a combustion reaction. Methods for synthesizing the nanocrystalline metal powders are characterized by forming a combustion synthesis solution by dissolving in water an oxidizer, a fuel, and a base-soluble, ammonium precursor of tungsten, molybdenum, rhenium, or niobium in amounts that yield a stoichiometric burn when combusted. The combustion synthesis solution is then heated to a temperature sufficient to substantially remove water and to initiate a self-sustaining combustion reaction. The resulting powder can be subsequently reduced to metal form by heating in a reducing gas environment.

  5. Melting of Uranium Metal Powders with Residual Salts

    International Nuclear Information System (INIS)

    Jin-Mok Hur; Dae-Seung Kang; Chung-Seok Seo

    2007-01-01

    The Advanced Spent Fuel Conditioning Process (ACP) of the Korea Atomic Energy Research Institute focuses on the conditioning of Pressurized Water Reactor spent oxide nuclear fuel. After the oxide reduction step of the ACP, the resultant metal powders containing ∼ 30 wt% residual LiCl-Li 2 O should be melted for a consolidation of the fine metal powders. In this study, we investigated the melting behaviors of uranium metal powders considering the effects of a LiCl-Li 2 O residual salt. (authors)

  6. Investigation of metal ions sorption of brown peat moss powder

    Science.gov (United States)

    Kelus, Nadezhda; Blokhina, Elena; Novikov, Dmitry; Novikova, Yaroslavna; Chuchalin, Vladimir

    2017-11-01

    For regularities research of sorptive extraction of heavy metal ions by cellulose and its derivates from aquatic solution of electrolytes it is necessary to find possible mechanism of sorption process and to choice a model describing this process. The present article investigates the regularities of aliovalent metals sorption on brown peat moss powder. The results show that sorption isotherm of Al3+ ions is described by Freundlich isotherm and sorption isotherms of Na+ i Ni2+ are described by Langmuir isotherm. To identify the mechanisms of brown peat moss powder sorption the IR-spectra of the initial brown peat moss powder samples and brown peat moss powder samples after Ni (II) sorption were studied. Metal ion binding mechanisms by brown peat moss powder points to ion exchange, physical adsorption, and complex formation with hydroxyl and carboxyl groups.

  7. Method and apparatus for the production of metal oxide powder

    Science.gov (United States)

    Harris, Michael T.; Scott, Timothy C.; Byers, Charles H.

    1992-01-01

    The present invention provides a method for preparing metal oxide powder. A first solution, which is substantially organic, is prepared. A second solution, which is an aqueous solution substantially immiscible in the first solution, is prepared and delivered as drops to the first solution. The drops of the second solution are atomized by a pulsed electric field forming micro-drops of the second solution. Reagents in the first solution diffuse into and react with reactants in the micro-drops of the second solution forming metal hydroxide or oxalate particles. The metal hydroxide or metal oxalate particles are then recovered and dried to produce the metal oxide powder. An apparatus for preparing a metal oxide powder is also disclosed.

  8. Characterization of Metal Powders Used for Additive Manufacturing

    OpenAIRE

    Slotwinski, JA; Garboczi, EJ; Stutzman, PE; Ferraris, CF; Watson, SS; Peltz, MA

    2014-01-01

    Additive manufacturing (AM) techniques1 can produce complex, high-value metal parts, with potential applications as critical parts, such as those found in aerospace components. The production of AM parts with consistent and predictable properties requires input materials (e.g., metal powders) with known and repeatable characteristics, which in turn requires standardized measurement methods for powder properties. First, based on our previous work, we assess the applicability of current standar...

  9. Characterization of Metal Powders Used for Additive Manufacturing

    Science.gov (United States)

    Slotwinski, JA; Garboczi, EJ; Stutzman, PE; Ferraris, CF; Watson, SS; Peltz, MA

    2014-01-01

    Additive manufacturing (AM) techniques1 can produce complex, high-value metal parts, with potential applications as critical parts, such as those found in aerospace components. The production of AM parts with consistent and predictable properties requires input materials (e.g., metal powders) with known and repeatable characteristics, which in turn requires standardized measurement methods for powder properties. First, based on our previous work, we assess the applicability of current standardized methods for powder characterization for metal AM powders. Then we present the results of systematic studies carried out on two different powder materials used for additive manufacturing: stainless steel and cobalt-chrome. The characterization of these powders is important in NIST efforts to develop appropriate measurements and standards for additive materials and to document the property of powders used in a NIST-led additive manufacturing material round robin. An extensive array of characterization techniques was applied to these two powders, in both virgin and recycled states. The physical techniques included laser diffraction particle size analysis, X-ray computed tomography for size and shape analysis, and optical and scanning electron microscopy. Techniques sensitive to structure and chemistry, including X-ray diffraction, energy dispersive analytical X-ray analysis using the X-rays generated during scanning electron microscopy, and X-Ray photoelectron spectroscopy were also employed. The results of these analyses show how virgin powder changes after being exposed to and recycled from one or more Direct Metal Laser Sintering (DMLS) additive manufacturing build cycles. In addition, these findings can give insight into the actual additive manufacturing process. PMID:26601040

  10. Characterization of Metal Powders Used for Additive Manufacturing.

    Science.gov (United States)

    Slotwinski, J A; Garboczi, E J; Stutzman, P E; Ferraris, C F; Watson, S S; Peltz, M A

    2014-01-01

    Additive manufacturing (AM) techniques can produce complex, high-value metal parts, with potential applications as critical parts, such as those found in aerospace components. The production of AM parts with consistent and predictable properties requires input materials (e.g., metal powders) with known and repeatable characteristics, which in turn requires standardized measurement methods for powder properties. First, based on our previous work, we assess the applicability of current standardized methods for powder characterization for metal AM powders. Then we present the results of systematic studies carried out on two different powder materials used for additive manufacturing: stainless steel and cobalt-chrome. The characterization of these powders is important in NIST efforts to develop appropriate measurements and standards for additive materials and to document the property of powders used in a NIST-led additive manufacturing material round robin. An extensive array of characterization techniques was applied to these two powders, in both virgin and recycled states. The physical techniques included laser diffraction particle size analysis, X-ray computed tomography for size and shape analysis, and optical and scanning electron microscopy. Techniques sensitive to structure and chemistry, including X-ray diffraction, energy dispersive analytical X-ray analysis using the X-rays generated during scanning electron microscopy, and X-Ray photoelectron spectroscopy were also employed. The results of these analyses show how virgin powder changes after being exposed to and recycled from one or more Direct Metal Laser Sintering (DMLS) additive manufacturing build cycles. In addition, these findings can give insight into the actual additive manufacturing process.

  11. Influences of the Air in Metal Powder High Velocity Compaction

    Directory of Open Access Journals (Sweden)

    Liu Jun

    2017-01-01

    Full Text Available During the process of metal powder high velocity impact compaction, the air is compressed sharply and portion remains in the compacts. In order to study the Influences, a discrete density volleyball accumulation model for aluminium powder was established with the use of ABAQUS. Study found that the powder porosity air obstruct the pressing process because remaining air reduced strength and density of the compacts in the current high-speed pressing (V≤100m/s. When speed further increased (V≥100m/s, the temperature of the air increased sharply, and was even much higher than the melting point of the material. When aluminium powder was compressed at a speed of 200m/s, temperatures of air could reach 2033 K, far higher than the melting point of 877 K. Increased density of powders was a result of local softening and even melt adhesive while air between particles with high temperature and pressure flowed past.

  12. Numerical modelling of cold compaction of metal powder

    DEFF Research Database (Denmark)

    Redanz, Pia

    1998-01-01

    model (J. Mech. Phys. Solids, 1992, 40(5), 1139-1162), developed by Fleck, Kuhr. and McMeeking, and a combination of the two models are used. The friction between the mould wall and the metal powder is modelled by a combination of Coulomb friction and a constant friction shear stress, since Coulomb...

  13. A general theory of the magnetic hyperfine interaction in paramagnetic metals

    International Nuclear Information System (INIS)

    Goetz, W.

    1993-09-01

    In this work a formalism is derived allowing to calculate the NMR properties Knight shift K, and spin-lattice relaxation time, 1/T 1 in addition to the magnetic susceptibility, χ 0 , of paramagnetic systems with the help of the spin-density and current-density correlation functions. The correlation functions are expressed through bandstructure Green's functions resulting from KKR and LMTO calculations; exchange and correlation effects are treated within the spin density functional theory (SDFA). The formalism derived has no adjustable parameters and all electrons are treated on the same footing. Thus applications to very different systems are possible. The first part of this treatise deals with the pressure dependent Knight shifts of the alkaline metals Na and Li. The various exchange-correlation potentials, K xc , described in the literature are employed in the present application and the results are compared with recent experimental data obtained by Bertani et al (1990). In the second part the quantities K, χ 0 and 1/T 1 of the hcp-transition metals Sc and Ru are calculated. The influence of many-body effects on the spin-lattice relaxation time of Sc is investigated for the first time. Furthermore, the contribution of the spin fluctuations to the specific heat of the electrons of Sc is calculated. To compare with the experimental data, the contribution of the phonons is also investigated. The last part of this work deals with the high-temperature superconductor YBa 2 Cu 3 O 7 . In this context the most important question is whether or not it is possible to describe this system within the SDFA. For this reason the quantities K, χ 0 , and 1/T 1 are calculated and compared with experimental results in detail. In addition, theinfluence of enhancement effects on the relaxation rate, 1/T 1 , is estimated. (orig.) [de

  14. Magnetic hyperfine anomalies

    International Nuclear Information System (INIS)

    Buettgenbach, S.

    1984-01-01

    This study is concerned with the measurement and interpretation of magnetic hyperfine anomalies in electronic and muonic atoms, i.e. effects of the distribution of nuclear magnetization on the magnetic dipole hyperfine interaction. After a summary of the relevant theory and a review of experimental techniques, hyperfine anomaly results are discussed in terms of various nuclear models. The use of the anomaly for yielding information about the origin of magnetic hyperfine interactions is outlined. Experimental and theoretical hyperfine anomalies are tabulated. (Auth.)

  15. Titanium Metal Powder Production by the Plasma Quench Process

    Energy Technology Data Exchange (ETDEWEB)

    R. A. Cordes; A. Donaldson

    2000-09-01

    The goals of this project included the scale-up of the titanium hydride production process to a production rate of 50 kg/hr at a purity level of 99+%. This goal was to be achieved by incrementally increasing the production capability of a series of reactor systems. This methodic approach was designed to allow Idaho Titanium Technologies to systematically address the engineering issues associated with plasma system performance, and powder collection system design and performance. With quality powder available, actual fabrication with the titanium hydride was to be pursued. Finally, with a successful titanium production system in place, the production of titanium aluminide was to be pursued by the simultaneously injection of titanium and aluminum precursors into the reactor system. Some significant accomplishments of the project are: A unique and revolutionary torch/reactor capable of withstanding temperatures up to 5000 C with high thermal efficiency has been operated. The dissociation of titanium tetrachloride into titanium powder and HC1 has been demonstrated, and a one-megawatt reactor potentially capable of producing 100 pounds per hour has been built, but not yet operated at the powder level. The removal of residual subchlorides and adsorbed HC1 and the sintering of powder to form solid bodies have been demonstrated. The production system has been operated at production rates up to 40 pounds per hour. Subsequent to the end of the project, Idaho Titanium Technologies demonstrated that titanium hydride powder can indeed be sintered into solid titanium metal at 1500 C without sintering aids.

  16. Changes in the hyperfine interactions in the Fe80Nb3Cu1B16 metallic glass under tensile loading

    Czech Academy of Sciences Publication Activity Database

    Jirásková, Yvonna; Zábranský, Karel; Vůjtek, M.; Životský, O.

    2010-01-01

    Roč. 322, č. 14 (2010), s. 1939-1946 ISSN 0304-8853 R&D Projects: GA ČR GD106/05/H008; GA ČR GA202/05/2111 Institutional research plan: CEZ:AV0Z20410507 Keywords : Amorphous alloys * Hyperfine interactions * Magnetic property * Tensile loading Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.689, year: 2010

  17. Laser stereolithography by multilayer cladding of metal powders

    Science.gov (United States)

    Jendrzejewski, Rafal; Rabczuk, Grazyna T.; Zaremba, R.; Sliwinski, Gerard

    1998-07-01

    3D-structures obtained by means of laser cladding of the metal alloy powders: bronze B10 and stellite 6 and the process parameters are studied experimentally. The structures are made trace-on-trace by remelting of the metal powder injected into the focusing region of the 1.2 kW CO2 laser beam. For the powder and sample feeding rates of 8-22 g/min and 0.4-1.2 m/min, respectively, and the applied beam intensities not exceeding 2 X 105 W cm-2 the process is stable and regular traces connected via fusion zones are produced for each material. The thickness of these zones does not exceed several per cent of the layer height. The process results in the efficient formation of multilayer structures. From their geometry the effect of energy coupling and interaction parameters are deduced. Moreover, the microanalysis by means of SEM- and optical photographs of samples produced under different experimental conditions confirms the expected mechanical properties, low porosity and highly homogenous structure of the multilayers. In addition to the known material stellite 6 the bronze B10 is originally proposed for a rapid prototyping.

  18. Research of plasma-electrolyte discharge in the processes of obtaining metallic powders

    Science.gov (United States)

    Kashapov, R. N.; Kashapov, L. N.; Kashapov, N. F.

    2017-11-01

    The use of the plasma electrolyte process has never been considered as a simple, cheap and fast method of obtaining powders used in selective laser melting processes. Therefore, the adaptation of the plasma-electrolyte process to the production of metal powders used in additive production is an urgent task. The paper presents the results of studies of gas discharge parameters between a metal and liquid electrode in the processes of obtaining metallic iron powders. The discharge combustion conditions necessary for the formation of metal powders of micron size are determined. A possible mechanism for the formation of powder particles in a discharge plasma is proposed.

  19. Flow characteristics of metallic powder grains for additive manufacturing

    Science.gov (United States)

    Peters, Bernhard; Pozzetti, Gabriele

    2017-06-01

    Directed energy deposition technologies for additive manufacturing such as laser selective melting (SLM) or electron beam melting (EBM) is a fast growing technique mainly due to its flexibility in product design. However, the process is a complex interaction of multi-physics on multiple length scales that are still not entirely understood. A particular challenging task are the flow characteristics of metallic powder ejected as jets from a nozzle and shielded by an inert turbulent gas flow. Therefore, the objective is to describe numerically the complex interaction between turbulent flow and powder grains. In order to include both several physical processes and length scales an Euler-Lagrange technology is applied. Within this framework powder is treated by the Discrete-Element-Method, while gas flow is described by Euler approaches as found in classical Computational Fluid Dynamics (CFD). The described method succeeded in delivering more accuracy and consistency than a standard approach based on the volume averaging technique and therefore, is suited for the solution of problems within an engineering framework.

  20. Flow characteristics of metallic powder grains for additive manufacturing

    Directory of Open Access Journals (Sweden)

    Peters Bernhard

    2017-01-01

    Full Text Available Directed energy deposition technologies for additive manufacturing such as laser selective melting (SLM or electron beam melting (EBM is a fast growing technique mainly due to its flexibility in product design. However, the process is a complex interaction of multi-physics on multiple length scales that are still not entirely understood. A particular challenging task are the flow characteristics of metallic powder ejected as jets from a nozzle and shielded by an inert turbulent gas flow. Therefore, the objective is to describe numerically the complex interaction between turbulent flow and powder grains. In order to include both several physical processes and length scales an Euler-Lagrange technology is applied. Within this framework powder is treated by the Discrete-Element-Method, while gas flow is described by Euler approaches as found in classical Computational Fluid Dynamics (CFD. The described method succeeded in delivering more accuracy and consistency than a standard approach based on the volume averaging technique and therefore, is suited for the solution of problems within an engineering framework.

  1. Preparation and pattern recognition of metallic Ni ultrafine powders by electroless plating

    International Nuclear Information System (INIS)

    Zhang, H.J.; Zhang, H.T.; Wu, X.W.; Wang, Z.L.; Jia, Q.L.; Jia, X.L.

    2006-01-01

    Using hydrazine hydrate as reductant, metallic Ni ultrafine powders were prepared from NiSO 4 aqueous solution by electroless plating method. The factors including concentration of NiSO 4 , bathing temperature, ratio of hydrazine hydrate to NiSO 4 , the pH of the solution, etc., on influence of the yield and average particle size of metallic Ni ultrafine powders were studied in detail. X-ray powders diffraction patterns show that the nickel powders are cubic crystallite. The average crystalline size of the ultrafine nickel powders is about 30 nm. The dielectric and magnetic loss of ultrafine Ni powders-paraffin wax composites were measured by the rectangle waveguide method in the range 8.2-12.4 GHz. The factors for Ni ultrafine powders preparation are optimized by computer pattern recognition program based on principal component analysis, the optimum factors regions with higher yield of metallic Ni ultrafine powders are indicated by this way

  2. Inhalation carcinogenicity study with nickel metal powder in Wistar rats

    International Nuclear Information System (INIS)

    Oller, Adriana R.; Kirkpatrick, Daniel T.; Radovsky, Ann; Bates, Hudson K.

    2008-01-01

    Epidemiological studies of nickel refinery workers have demonstrated an association between increased respiratory cancer risk and exposure to certain nickel compounds (later confirmed in animal studies). However, the lack of an association found in epidemiological analyses for nickel metal remained unconfirmed for lack of robust animal inhalation studies. In the present study, Wistar rats were exposed by whole-body inhalation to 0, 0.1, 0.4, and 1.0 mg Ni/m 3 nickel metal powder (MMAD = 1.8 μm, GSD = 2.4 μm) for 6 h/day, 5 days/week for up to 24 months. A subsequent six-month period without exposures preceded the final euthanasia. High mortality among rats exposed to 1.0 mg Ni/m 3 nickel metal resulted in the earlier termination of exposures in this group. The exposure level of 0.4 mg Ni/m 3 was established as the MTD for the study. Lung alterations associated with nickel metal exposure included alveolar proteinosis, alveolar histiocytosis, chronic inflammation, and bronchiolar-alveolar hyperplasia. No increased incidence of neoplasm of the respiratory tract was observed. Adrenal gland pheochromocytomas (benign and malignant) in males and combined cortical adenomas/carcinomas in females were induced in a dose-dependent manner by the nickel metal exposure. The incidence of pheochromocytomas was statistically increased in the 0.4 mg Ni/m 3 male group. Pheochromocytomas appear to be secondary to the lung toxicity associated with the exposure rather than being related to a direct nickel effect on the adrenal glands. The incidence of cortical tumors among 0.4 mg Ni/m 3 females, although statistically higher compared to the concurrent controls, falls within the historical control range; therefore, in the present study, this tumor is of uncertain relationship to nickel metal exposure. The lack of respiratory tumors in the present animal study is consistent with the findings of the epidemiological studies

  3. Ultrasonic characterization of microstructure in powder metal alloy

    Science.gov (United States)

    Tittmann, B. R.; Ahlberg, L. A.; Fertig, K.

    1986-01-01

    The ultrasonic wave propagation characteristics were measured for IN-100, a powder metallurgy alloy used for aircraft engine components. This material was as a model system for testing the feasibility of characterizing the microstructure of a variety of inhomogeneous media including powder metals, ceramics, castings and components. The data were obtained for a frequency range from about 2 to 20 MHz and were statistically averaged over numerous volume elements of the samples. Micrographical examination provided size and number distributions for grain and pore structure. The results showed that the predominant source for the ultrasonic attenuation and backscatter was a dense (approx. 100/cubic mm) distribution of small micropores (approx. 10 micron radius). Two samples with different micropore densities were studied in detail to test the feasibility of calculating from observed microstructural parameters the frequency dependence of the microstructural backscatter in the regime for which the wavelength is much larger than the size of the individual scattering centers. Excellent agreement was found between predicted and observed values so as to demonstrate the feasibility of solving the forward problem. The results suggest a way towards the nondestructive detection and characterization of anomalous distributions of micropores when conventional ultrasonic imaging is difficult. The findings are potentially significant toward the application of the early detection of porosity during the materials fabrication process and after manufacturing of potential sites for stress induced void coalescence leading to crack initiation and subsequent failure.

  4. METHOD OF PRODUCING SHAPED BODIES FROM POWDERED METALS

    Science.gov (United States)

    Blainey, A.

    1960-05-31

    A method is given for enclosing a body of uranium in a sheath of compacted beryllium or zirconium powder and comprises enveloping the body with uncompacted powder and pressing at a temperature above the beta - gamma transition point of uranium, thereby causing the uranium to flow and isotropically compress the powder.

  5. Thermochemical treatment of radioactive waste by using powder metal fuels

    International Nuclear Information System (INIS)

    Dmitriev, S.A.; Ojovan, M.I.; Karlina, O.K.

    2001-01-01

    Full text: A thermochemical approach was suggested for treating and conditioning specific streams of radioactive wastes for example spent ion exchange resins, mixed, organic or chlorine-containing radioactive waste as well as in order to decontaminate heavily contaminated surfaces. Conventional treatment methods of such waste encounters serious problems concerning complete destruction of organic molecules and possible emissions of radionuclides, heavy metals and chemically hazardous species or in case of contaminated materials - complete removal of contamination from surface. The thermochemical treatment of radioactive waste uses powdered metal fuels (PMF) that are specifically formulated for the waste composition and react chemically with the waste components. Thermochemical treatment technologies use the energy of chemical reactions in the mixture of waste with PMF to sustain both decomposition and synthesis processes as well as processes of isomorphic substitutions of hazardous elements into stable mineral forms. The composition of the PMF is designed in such a way as to minimise the release of hazardous components and radionuclides in the off gas and to confine the contaminants in the mineral or glass like final products. The thermochemical procedures allow decomposition of organic matter and capturing hazardous radionuclides and chemical species simultaneously. Thermochemical treatment technologies are very efficient, easy to apply, they have low capital investment and can be used both at large and small facilities. An advantage of thermochemical technologies is their autonomy. Thus these technologies can be successfully applied in order to treat small amount of waste without usage of complex and expensive equipment. They can be used also in emergency situations. Currently the thermochemical treatment technologies were developed and demonstrated to be feasible as follows: 1. Decontamination of surfaces; 2. Processing of organic waste; 3. Vitrification of dusty

  6. Development of indigenous laboratory scale gas atomizer for producing metal powders

    International Nuclear Information System (INIS)

    Khan, K.K.; Qasim, A.M.; Ahmed, P.

    2011-01-01

    Gas atomization is one of the methods for production of clean metal powders at relatively moderate cost. A laboratory scale gas atomizer was designed and fabricated indigenously to produce metal powders with a batch capacity of 500 g of copper (Cu). The design includes several features regarding fabrication and operation to provide optimum conditions for atomization. The inner diameter of atomizing chamber is 440 mm and its height is 1200 mm. The atomizing nozzle is of annular confined convergent type with an angle of 25 degree. Argon gas at desired pressure has been used for atomizing the metals to produce relatively clean powders. A provision has also been made to view the atomization process. The indigenous laboratory scale gas atomizer was used to produce tin (Sn) and copper (Cu) powders with different atomizing gas pressures ranging from 2 to 10 bar. The particle size of different powders produced ranges from 40 to 400 im. (author)

  7. Gas sensing properties of nanocrystalline metal oxide powders produced by thermal decomposition and mechanochemical processing

    OpenAIRE

    Kersen, Ülo

    2003-01-01

    The objective of this research, was the synthesis of LaFeO3 and SnO2 fine powders for the subsequent preparation of thick film gas sensors. On producing fine metal oxide powders, often it is not possible to ensure separation of the particles during the synthesis, resulting in the formation of highly agglomerated material. In addition, there are often high synthetic costs associated with the powders obtained by these methods. Thermal decomposition and mechanochemical processing methods wer...

  8. RESEARCH OF HEAVY METALS, ORGANOCHLORINE AND ORGANOPHOSPHORUS PESTICIDES IN POWDERED INFANT FORMULA

    Directory of Open Access Journals (Sweden)

    M.C. Abete

    2009-02-01

    Full Text Available During the period between october 2007 and november 2008 were collected 60 samples of powdered infant formula. The analysis for the detection of heavy metals, organochlorine and organophosphorus pesticides show that the environmental situation is under control and powdered infant formula satisfies this health requisite.

  9. Powder metallurgical processing and metal purity: A case for ...

    Indian Academy of Sciences (India)

    Unknown

    morphology of the tantalum powder and the work on leakage has been done on the oxide film. The emphasis has been on the improvement of the dielectric film to lower the leakage and increase the breakdown voltage. Most finished powders made by the sodium reduction process have a complex nodular morphology.

  10. Physical characterization of steel and stainless steel metal powders

    International Nuclear Information System (INIS)

    Lavilla, A.O.; Lucchesi, C.G.; Sandin, O.O.

    1991-01-01

    A methodology has been developed for the physical characterization of steel powders (obtained by atomization) for later sintering and for the construction of porous sheets and filtrating tubes, capable of operating at temperatures between 600 deg C and 800 deg C in corrosive atmospheres. This methodology was based on the equipment and methods used for the physical characterization of uranium oxide powders. (Author) [es

  11. The role of the native oxide shell on the microwave sintering of copper metal powder compacts

    International Nuclear Information System (INIS)

    Mahmoud, Morsi M.; Link, Guido; Thumm, Manfred

    2015-01-01

    Highlights: • Thin oxide native layer had a critical role on microwave sintering of copper. • Explain why microwaves interact with copper powder differently than its bulk. • Abnormal expansion in copper is due to the plastic deformation and crack formation. • In-situ setup gives important insight about the microwave sintering of metals. • Microwave sintering is a promising candidate technology in powder metallurgy. - Abstract: Successful microwave sintering of several metal powders had been reported by many researchers with remarkable improvements in the materials properties and/or in the overall process. However, the concept behind microwave heating of metal powders has not been fully understood till now, as it is well known that bulk metals reflect microwaves. The progress of microwave sintering of copper metal powder compacts was investigated via combining both in-situ electrical resistivity and dilatometry measurements that give important information about microstructural changes with respect to the inter-particle electrical contacts during sintering. The sintering behavior of copper metal powders was depending on the type of the gas used, particle size, the initial green density, the soaking sintering time and the thin oxide layer on the particles surfaces. The thin copper oxide native layer (ceramics) that thermodynamically formed on the particles surfaces under normal handling and ambient environmental conditions had a very critical and important role in the microwave absorption and interaction, the sintering behavior and the microstructural changes. This finding could help to have a fundamental understanding of why MW’s interact with copper metal powder in a different way than its bulk at room temperature, i.e. why a given metal powder could be heated using microwaves while its bulk reflects it

  12. Physical and chemical characterization techniques for metallic powders

    International Nuclear Information System (INIS)

    Slotwinski, J. A.; Stutzman, P. E.; Ferraris, C. F.; Watson, S. S.; Peltz, M. A.; Garboczi, E. J.

    2014-01-01

    Systematic studies have been carried out on two different powder materials used for additive manufacturing: stainless steel and cobalt-chrome. An extensive array of characterization techniques were applied to these two powders. The physical techniques included laser-diffraction particle-size analysis, X-ray computed tomography for size and shape analysis, and optical and scanning electron microscopy. Techniques sensitive to chemistry included X-ray diffraction and energy-dispersive analytical X-ray analysis. The background of these techniques will be summarized and some typical findings comparing different samples of virgin additive manufacturing powders, taken from the same lot, will be given. The techniques were used to confirm that different samples of powder from the same lot were essentially identical, within the uncertainty of the measurements

  13. Effect of Ekabor 2 powder on the mechanical properties of pure iron powder metal compacts

    Energy Technology Data Exchange (ETDEWEB)

    Altintas, A.; Sarigun, Y.; Cavdar, U.

    2016-07-01

    Ekabor 2 powder of different weights, used by V type powder mixture was mixed with pure iron powder. Specimens were created by dry pressing into die followed by cold isostatic press at a pressure of 100 bar for purpose of resizing. The conventional sintering process at 900 °C and 950 °C was carried out for 4 h using conventional furnaces. Specimens were gradually cooled by air. The sintered pellets were examined in terms of density, wear abrasion, surface roughness and hardness at 900 °C and 950 °C. Microstructure of pellets was observed with optic microscope. The results show that the hardness gradually increased with additions of 0 wt. % to 10 wt. % of Ekabor 2 however, after 10 wt. %, this hardness tended to decrease. (Author)

  14. Thermal analysis and evolution of shape loss phenomena during polymer burnout in powder metal processing

    Science.gov (United States)

    Enneti, Ravi Kumar

    2005-07-01

    Powder metallurgy technology involves manufacturing of net shape or near net shape components starting from metal powders. Polymers are used to provide lubrication during shaping and handling strength to the shaped component. After shaping, the polymers are removed from the shaped components by providing thermal energy to burnout the polymers. Polymer burnout is one of the most critical step in powder metal processing. Improper design of the polymer burnout cycle will result in formation of defects, shape loss, or carbon contamination of the components. The effect of metal particles on polymer burnout and shape loss were addressed in the present research. The study addressing the effect of metal powders on polymer burnout was based on the hypothesis that metal powders act to catalyze polymer burnout. Thermogravimetric analysis (TGA) on pure polymer, ethylene vinyl acetate (EVA), and on admixed powders of 316L stainless steel and 1 wt. % EVA were carried out to verify the hypothesis. The effect of metal powders additions was studied by monitoring the onset temperature for polymer degradation and the temperature at which maximum rate of weight loss occurred from the TGA data. The catalytic behavior of the powders was verified by varying the particle size and shape of the 316L stainless powder. The addition of metal particles lowered the polymer burnout temperatures. The onset temperature for burnout was found to be sensitive to the surface area of the metal particle as well as the polymer distribution. Powders with low surface area and uniform distribution of polymer showed a lower burnout temperature. The evolution of shape loss during polymer burnout was based on the hypothesis that shape loss occurs during the softening of the polymer and depends on the sequence of chemical bonding in the polymer during burnout. In situ observation of shape loss was carried out on thin beams compacted from admixed powders of 316L stainless steel and 1 wt. % ethylene vinyl acetate

  15. Application of physical and chemical characterization techniques to metallic powders

    International Nuclear Information System (INIS)

    Slotwinski, J. A.; Watson, S. S.; Stutzman, P. E.; Ferraris, C. F.; Peltz, M. A.; Garboczi, E. J.

    2014-01-01

    Systematic studies have been carried out on two different powder materials used for additive manufacturing: stainless steel and cobalt-chrome. The characterization of these powders is important in NIST efforts to develop appropriate measurements and standards for additive materials and to document the property of powders used in a NIST-led additive manufacturing material round robin. An extensive array of characterization techniques was applied to these two powders, in both virgin and recycled states. The physical techniques included laser diffraction particle size analysis, X-ray computed tomography for size and shape analysis, and optical and scanning electron microscopy. Techniques sensitive to chemistry, including X-ray diffraction and energy dispersive analytical X-ray analysis using the X-rays generated during scanning electron microscopy, were also employed. Results of these analyses will be used to shed light on the question: how does virgin powder change after being exposed to and recycled from one or more additive manufacturing build cycles? In addition, these findings can give insight into the actual additive manufacturing process

  16. Numerical modelling of cold compaction of metal powder

    DEFF Research Database (Denmark)

    Redanz, Pia

    1998-01-01

    A finite element programme has been developed for the analysis of porosity and stress distributions in a powder compact, based on rate-independent finite strain plasticity theory. The strain hardening versions of the Gurson model (J. Engng. Mater. Technol., 1977, 99, 2-15), the more recent FKM...... friction is not realistic at high normal pressures. The finite element programme has been used to study the effects of friction, compaction method, and material parameters. Analyses for powder compacts of various geometries are presented to illustrate the method. (C) 1998 Elsevier Science Ltd. All rights...

  17. Powder metallurgical processing and metal purity: A case for ...

    Indian Academy of Sciences (India)

    The paper reviews the role of sintered tantalum as volumetric efficient electrical capacitor. Powder characteristics and sintering aspects are discussed. The role of impurities in influencing the electrical properties has been described. Today's driving force behind the Ta market is the use of surface mounted versions known as ...

  18. Micro powder-injection moulding of metals and ceramics

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    it combines the possibility of large-scale serial production with a wide range of materials, so that it has great ... ing allows an extraction of up to 80% of the binder within one hour and thus works sufficiently well, additional .... Merz L 1997 Development of a polymer binder for powder injection moulding and binder extraction.

  19. Powder metallurgical processing and metal purity: A case for ...

    Indian Academy of Sciences (India)

    Unknown

    Next, the anodized pellet is impregnated with manganese nitrate which is then thermally decomposed to leave or deposit semiconducting manganese dioxide on ... In order to improve physical properties of powder, they are generally agglomerated. But this heat treatment causes the surface oxygen to dissolve in the bulk.

  20. Micro powder-injection moulding of metals and ceramics

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    An exception is micro powder-injection moulding, because it combines the possibility of large-scale serial production with a wide range of materials, so that it has great economic potential (Rota et al 1998; Piotter et al 1999). Therefore, the special features and possibilities of micro injection moulding in general are described ...

  1. Development of new metal matrix composite electrodes for electrical discharge machining through powder metallurgy process

    Directory of Open Access Journals (Sweden)

    C. Mathalai Sundaram

    2014-12-01

    Full Text Available Electrical discharge machining (EDM is one of the widely used nontraditional machining methods to produce die cavities by the erosive effect of electrical discharges. This method is popular due to the fact that a relatively soft electrically conductive tool electrode can machine hard work piece. Copper electrode is normally used for machining process. Electrode wear rate is the major drawback for EDM researchers. This research focus on fabrication of metal matrix composite (MMC electrode by mixing copper powder with titanium carbide (TiC and Tungsten carbide (WC powder through powder metallurgy process, Copper powder is the major amount of mixing proportion with TiC and WC. However, this paper focus on the early stage of the project where powder metallurgy route was used to determine suitable mixing time, compaction pressure and sintering and compacting process in producing EDM electrode. The newly prepared composite electrodes in different composition are tested in EDM for OHNS steel.

  2. Novel Route to Transition Metal Isothiocyanate Complexes Using Metal Powders and Thiourea

    Science.gov (United States)

    Harris, Jerry D.; Eckles, William E.; Hepp, Aloysius F.; Duraj, Stan A.; Hehemann, David G.; Fanwick, Phillip E.; Richardson, John

    2003-01-01

    A new synthetic route to isothiocyanate-containing materials is presented. Eight isothiocyanate- 4-methylpyridine (y-picoline) compounds were prepared by refluxing metal powders (Mn, Fe, Co, Ni, and Cu) with thiourea in y-picoline. With the exception of compound 5,prepared with Co, the isothiocyanate ligand was generated in situ by the isomerization of thiourea to NH4+SCN- at reflux temperatures. The complexes were characterized by x-ray crystallography. Compounds 1,2, and 8 are the first isothiocyanate- 4-methylpyridine anionic compounds ever prepared and structurally characterized. Compounds 1 and 2 are isostructural with four equatorially bound isothiocyanate ligands and two axially bound y-picoline molecules. Compound 8 is a five-coordinate copper(II) molecule with a distorted square-pyramidal geometry. Coordinated picoline and two isothiocyanates form the basal plane and the remaining isothiocyanate is bound at the apex. Structural data are presented for all compounds.

  3. Chemical reactions of metal powders with organic and inorganic liquids during ball milling

    Science.gov (United States)

    Arias, A.

    1975-01-01

    Chromium and/or nickel powders were milled in metal chlorides and in organic liquids representative of various functional groups. The powders always reacted with the liquid and became contaminated with elements from them. The milled powders had specific surface areas ranging from 0.14 to 37 sq m/g, and the total contamination with elements from the milling liquid ranged from 0.01 to 56 weight percent. Compounds resulting from substitution, addition, or elimination reactions formed in or from the milling liquid.

  4. Study of the hyperfine properties of the nickel-zinc ferrite using coprecipitation process; Estudo das propriedades hiperfinas de ferrita de niquel e zinco obtida por coprecipitacao

    Energy Technology Data Exchange (ETDEWEB)

    Albuquerque, Adriana Silva de; Almeida Macedo, Waldemar Augusto de [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil)

    1996-09-01

    In this work were studied the synthesis by coprecipitation of the Ni Zn ferrite, Ni {sub 0,5} Zn{sub 0,5} Fe{sub 2} O{sub 4}``, and its hyperfine properties. The ferrite specimens were prepared using metallic nitrates in aqueous solutions as precursor agents and the precipitation processes were promoted by addition of ammonium or sodium hydroxide. The obtained powders were calcined and characterized by X-ray diffraction and fluorescence, and by {sup 57} Fe Moessbauer spectroscopy. The liquid phase was analysed by atomic absorption. The samples of stoichiometric Ni Zn ferrite were obtained using Na O H as precipitating agent. The ferrite powders presented different particles size related with changing in the preparation method,and then, different hyperfine properties. Moessbauer effect measurements reveled the superparamagnetic nature of the ferrite samples that presented particles size smaller than 30 nm. (author) 9 refs., 3 figs., 3 tabs.

  5. Nanocrystalline metal-superconductor powders produced by aerosol decomposition

    International Nuclear Information System (INIS)

    Carim, A.H.; Doherty, P.; Kodas, T.T.

    1990-01-01

    This paper reports on composite silver---YBa 2 Cu 3 O 7-δ powders with nanocrystalline and larger sizes produced by aerosol techniques at 1000 degrees C and 930 degrees C. Silver is incorporated primarily in the elemental form, although particles of hexagonal Ag 2 O are also observed when the reactor is operated below the Ag-O eutectic temperature (939 degree C). Longer reactor residence times (>35 s, as opposed to c > 90K) can still be obtained in the composite powders. Aerosol decomposition of Y-Ba-Cu nitrate precursors with Pt additions did not produce superconductive material; instead, most of the resultant particles were Pt-Y-Ba-Cu-O compounds

  6. Fluidized Bed Sputtering for Particle and Powder Metallization

    Science.gov (United States)

    2013-04-01

    Sathiyamoorthy provides a review of plasma technology used with fluidized bed techniques (13). Borer and von Rohr integrated a microwave plasma source...Plasma Spouted/Fluidized Bed for Materials Processing. Journal of Physics: Conference Series 2010, 208 (1), 012120. 14. Borer, B.; von Rohr , R...Technology 2005, 200, 377–381. 15. Morstein, M.; Karches, M.; Bayer, C.; Casanova, D.; von Rohr , P. R. Plasma CVD of Ultrathin TiO2 Films on Powders in a

  7. Removing metal debris from thermosetting EMC powders by Nd-Fe-B permanent magnets

    Directory of Open Access Journals (Sweden)

    Liaw Yowching

    2017-01-01

    Full Text Available During the preparation of thermosetting encapsulation molding compounds (EMCs for semiconductor packaging, metal debris are always present in the EMC powders due to the hard silica fillers in the compound. These metal debris in the EMC powders will cause circuit shortage and therefore have to be removed before molding. In this study, Nd-Fe-B permanent magnets are used to remove these debris. The results show that the metal debris can be removed effectively as the rate of accumulation of the metal debris increases as time proceeds in the removing operation. The removal effectiveness of the debris is affected by both the magnetic flux density and the flow around the magnet. The wake flow behind the magnet is a relatively low speed recirculation region which facilities the attraction of metal debris in the powders. Thus, the largest amount of the accumulated EMC powders occurs downstream of the magnet. Hence, this low speed recirculation region should be better utilized to enhance the removal efficiency of the metal debris.

  8. Neutron powder diffraction of metal-organic frameworks for ...

    Indian Academy of Sciences (India)

    Abstract. We review recent structural studies that we have undertaken aimed at eluci- dating the fundamental properties of metal-organic framework materials and their inter- actions with hydrogen. We have shown that exposing coordinatively unsaturated metal centers can greatly enhance the hydrogen binding energy and ...

  9. Neutron powder diffraction of metal-organic frameworks for ...

    Indian Academy of Sciences (India)

    We review recent structural studies that we have undertaken aimed at elucidating the fundamental properties of metal-organic framework materials and their interactions with hydrogen. We have shown that exposing coordinatively unsaturated metal centers can greatly enhance the hydrogen binding energy and that they ...

  10. Hyperfine interactions in metallic catalysts

    International Nuclear Information System (INIS)

    Saitovitch, Henrique; Silva, Paulo R.J.; Passos, Fabio B.

    2005-01-01

    Heterogeneous catalysts are of fundamental importance in several modern chemical processes. The characterization of catalysts is an issue of very present interest as it can provide a better understanding of the fundamental aspects of the catalytic phenomena, thus helping in the development of more efficient catalysts. In order to extend and improve the characterization of catalysts, new and less conventional methods are being applied, such as nuclear spectroscopies. In this paper we focus on the application of angular correlation, with can be used to resolve different local environments of probe atoms in solids and can be applied, as shown here, in the characterization of heterogeneous catalysts. A brief theoretical introduction is given and experimental results related to catalytic systems of alumina and niobia-supported Pt-In and Pd-In catalysts are presented. (author)

  11. Hopper design for metallic powders used in additive manufacturing processes

    CSIR Research Space (South Africa)

    Visagie, N

    2013-10-01

    Full Text Available . The coefficient of wall friction (external friction) is the amount of friction developed between the wall of the hopper and the solid particles in contact with it. The coefficient of wall friction is measured using a shear cell test. Although not always true... to volume. The standard method for determining hopper design parameters is known as the Jenike method and is described in ASTM standard D6128. Powder is tested in a shear cell tester to determine friction coefficients which are used in a mathematic...

  12. Characterization of the whiskerlike products formed by hydriding magnesium metal powders

    DEFF Research Database (Denmark)

    Herley, P. J.; Jones, W.; Vigeholm, Bjørn

    1985-01-01

    The structure of filamentary crystals produced during the hydriding of magnesium powder has been studies in detail. The needles of small dimensions (typically 0.5 μm in diameter) have been identified by electron analytical techniques to be oriented microcrystals of metallic magnesium...

  13. Improving resistance welding of aluminum sheets by addition of metal powder

    DEFF Research Database (Denmark)

    Al Naimi, Ihsan K.; Al-Saadi, Moneer H.; Daws, Kasim M.

    2015-01-01

    2024 and AA7075) are investigated for the resistance spot welding of AA1050 aluminum sheets of three different thicknesses. Microstructural and mechanical analysis demonstrates that significant improvement in weld bead morphology and strength are obtained with the addition of metal powder...

  14. Voltammetry of metallic powder suspensions on mercury electrodes

    Czech Academy of Sciences Publication Activity Database

    Korshunov, A.; Heyrovský, Michael

    2006-01-01

    Roč. 18, č. 4 (2006), s. 423-426 ISSN 1040-0397 R&D Projects: GA MPO 1H-PK/42 Institutional research plan: CEZ:AV0Z40400503 Keywords : metallic particles * oxide layers * suspensions * mercury electrodes * particulate electrolysis Subject RIV: CG - Electrochemistry Impact factor: 2.444, year: 2006

  15. Sonochemical water splitting in the presence of powdered metal oxides.

    Science.gov (United States)

    Morosini, Vincent; Chave, Tony; Virot, Matthieu; Moisy, Philippe; Nikitenko, Sergey I

    2016-03-01

    Kinetics of hydrogen formation was explored as a new chemical dosimeter allowing probing the sonochemical activity of argon-saturated water in the presence of micro- and nano-sized metal oxide particles exhibiting catalytic properties (ThO2, ZrO2, and TiO2). It was shown that the conventional sonochemical dosimeter based on H2O2 formation is hardly applicable in such systems due to catalytic degradation of H2O2 at oxide surface. The study of H2 generation revealed that at low-frequency ultrasound (20 kHz) the sonochemical water splitting is greatly improved for all studied metal oxides. The highest efficiency is observed for relatively large micrometric particles of ThO2 which is assigned to ultrasonically-driven particle fragmentation accompanied by mechanochemical water molecule splitting. The nanosized metal oxides do not exhibit particle size reduction under ultrasonic treatment but nevertheless yield higher quantities of H2. The enhancement of sonochemical water splitting in this case is most probably resulting from better bubble nucleation in heterogeneous systems. At high-frequency ultrasound (362 kHz), the effect of metal oxide particles results in a combination of nucleation and ultrasound attenuation. In contrast to 20 kHz, micrometric particles slowdown the sonolysis of water at 362 kHz due to stronger attenuation of ultrasonic waves while smaller particles show a relatively weak and various directional effects. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Mathematical Model of Hot Metal Desulfurization by Powder Injection

    Directory of Open Access Journals (Sweden)

    Yolanda Cepeda Rodríguez

    2012-01-01

    Full Text Available Although there have been a numerous number of studies on mathematical model of hot metal desulfurization by deep injection of calcium carbide, the research field as a whole is not well integrated. This paper presents a model that takes into account the kinetics, thermodynamics, and transport processes to predict the sulfur levels in the hot metal throughout a blow. The model could be utilized to assess the influence of the treatment temperature, rate of injection, gas flow rate, and initial concentration of sulfur on the desulfurization kinetics. In the second part of this paper an analysis of the industrial data for injection of calcium carbide using this model is described. From a mathematical model that describes the characteristics of a system, it is possible to predict the behavior of the variables involved in the process, resulting in savings of time and money. Discretization is realized through the finite difference method combined with interpolation in the border domain by Taylor series.

  17. PVC-based composite material containing recycled non-metallic printed circuit board (PCB) powders.

    Science.gov (United States)

    Wang, Xinjie; Guo, Yuwen; Liu, Jingyang; Qiao, Qi; Liang, Jijun

    2010-12-01

    The study is directed to the use of non-metallic powders obtained from comminuted recycled paper-based printed circuit boards (PCBs) as an additive to polyvinyl chloride (PVC) substrate. The physical properties of the non-metallic PCB (NMPCB) powders were measured, and the morphological, mechanical and thermal properties of the NMPCB/PVC composite material were investigated. The results show that recycled NMPCB powders, when added below a threshold, tended to increase the tensile strength and bending strength of PVC. When 20 wt% NMPCB powders (relative to the substrate PVC) of an average diameter of 0.08 mm were added, the composite tensile strength and bending strength reached 22.6 MPa and 39.83 MPa, respectively, representing 107.2% and 123.1% improvement over pure PVC. The elongation at break of the composite material reached 151.94% of that of pure PVC, while the Vicat softening temperature of the composite material did not increase significantly compared to the pure PVC. The above results suggest that paper-based NMPCB powders, when used at appropriate amounts, can be effective for toughening PVC. Thus, this study suggests a new route for reusing paper-based NMPCB, which may have a significant beneficial environmental impact. Copyright © 2010 Elsevier Ltd. All rights reserved.

  18. Scalar relativistic calculations of hyperfine coupling constants using ab initio density matrix renormalization group method in combination with third-order Douglas-Kroll-Hess transformation: case studies on 4d transition metals.

    Science.gov (United States)

    Nguyen Lan, Tran; Kurashige, Yuki; Yanai, Takeshi

    2015-01-13

    We have developed a new computational scheme for high-accuracy prediction of the isotropic hyperfine coupling constant (HFCC) of heavy molecules, accounting for the high-level electron correlation effects, as well as the scalar-relativistic effects. For electron correlation, we employed the ab initio density matrix renormalization group (DMRG) method in conjunction with a complete active space model. The orbital-optimization procedure was employed to obtain the optimized orbitals required for accurately determining the isotropic HFCC. For the scalar-relativistic effects, we initially derived and implemented the Douglas-Kroll-Hess (DKH) hyperfine coupling operators up to the third order (DKH3) by using the direct transformation scheme. A set of 4d transition-metal radicals consisting of Ag atom, PdH, and RhH2 were chosen as test cases. Good agreement between the isotropic HFCC values obtained from DMRG/DKH3 and experiment was archived. Because there are no available gas-phase values for PdH and RhH2 radicals in the literature, the results from the present high-level theory may serve as benchmark data.

  19. Crystallization behaviour and thermal stability of two aluminium-based metallic glass powder materials

    Energy Technology Data Exchange (ETDEWEB)

    Li, X.P.; Yan, M. [University of Queensland, School of Mechanical and Mining Engineering, ARC Centre of Excellence for Design in Light Metals, Brisbane, QLD 4072 (Australia); Yang, B.J. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wang, J.Q., E-mail: jqwang@imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Schaffer, G.B. [University of Queensland, School of Mechanical and Mining Engineering, ARC Centre of Excellence for Design in Light Metals, Brisbane, QLD 4072 (Australia); Qian, M., E-mail: ma.qian@uq.edu.au [University of Queensland, School of Mechanical and Mining Engineering, ARC Centre of Excellence for Design in Light Metals, Brisbane, QLD 4072 (Australia)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer The crystallization paths and products of Al{sub 86}Ni{sub 7}Y{sub 4.5}Co{sub 1}La{sub 1.5} powder have been identified. Black-Right-Pointing-Pointer The thermal stability of Al{sub 86}Ni{sub 7}Y{sub 4.5}Co{sub 1}La{sub 1.5} powder has been assessed. Black-Right-Pointing-Pointer The Al{sub 86}Ni{sub 7}Y{sub 4.5}Co{sub 1}La{sub 1.5} powder shows a wide processing window of 75 K. Black-Right-Pointing-Pointer The powder has the potential to be consolidated into thick BMG components based on the findings. Black-Right-Pointing-Pointer The Al{sub 85}Ni{sub 5}Y{sub 6}Co{sub 2}Fe{sub 2} powder shows similar characteristics but inferior thermal stability. - Abstract: The crystallization behaviour and thermal stability of two Al-based metallic glass powder materials, Al{sub 85}Ni{sub 5}Y{sub 6}Co{sub 2}Fe{sub 2} and Al{sub 86}Ni{sub 6}Y{sub 4.5}Co{sub 2}La{sub 1.5}, have been investigated using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and electron microscopy. Both alloy powders show a distinct three-stage crystallization process with a similar gap of {approx}75 K between the onset crystallization temperature (T{sub x}) and the second crystallization temperature. Crystallization occurs by the precipitation and growth of fcc-Al, without intermetallic formation. The apparent activation energy for each stage of crystallization was determined from DSC analyses and the phases resulting from each crystallization stage were identified by XRD and electron microscopy. The critical cooling rate for each alloy powder was calculated from the DSC data. These results are necessary to inform the consolidation of amorphous powder particles of Al{sub 85}Ni{sub 5}Y{sub 6}Co{sub 2}Fe{sub 2} or Al{sub 86}Ni{sub 6}Y{sub 4.5}Co{sub 2}La{sub 1.5} into thick (>1 mm) metallic glass components.

  20. X-ray absorption spectroscopic studies of the blue copper site: Metal and ligand K-edge studies to probe the origin of the EPR hyperfine splitting in plastocyanin

    International Nuclear Information System (INIS)

    Shadle, S.E.; Penner-Hahn, J.E.; Schugar, H.J.; Hedman, B.; Hodgson, K.O.; Solomon, E.I.

    1993-01-01

    X-ray absorption spectra for the oxidized blue copper protein plastocyanin and several Cu(II) model complexes have been measured at both the Cu K-edge and the ligand K-edges (Cl and S) in order to elucidate the source of the small parallel hyperfine splitting in the EPR spectra of blue copper centers. Assignment and analysis of a feature in the Cu K-edge X-ray absorption spectrum at ∼8,987 eV as the Cu 1s → 4p + ligand-to-metal charge-transfer shakedown transition has allowed for quantitation of 4p mixing into the ground-state wave function as reflected in the 1s →3d (+4p) intensity at ∼8,979 eV. The results show that distorted tetrahedral (D 2d )CuCl 4 2- is characterized by z mixing, while plastocyanin has only Cu 4p xy mixing. Thus, the small parallel hyperfine splitting in the EPR spectra of D 2d CuCl 4 2- and of oxidized plastocyanin cannot be explained by 12% 4p z mixing into the 3d x 2 -y 2 orbital as had been previously postulated. Data collected at the Cl K-edge for CuCl 4 2- show that the intensity of the ligand pre-edge feature at ∼2,820 eV reflects the degree of covalency between the metal half-occupied orbital and the ligands. The data show that D 2d CuCl 4 2- is not unusually covalent. The source of the small parallel splitting in the EPR of D 2d CuCl 4 2- is discussed. Experiments at the S K-edge (∼2,470 eV) show that plastocyanin is characterized by a highly covalent Cu-S(cysteine) bond relative to the cupric-thiolate model complex [Cu(tet b)(o-SC 6 H 4 CO 2 )]·H 2 O. The XAS results demonstrate that the small parallel hyperfine splitting in the EPR spectra of blue copper sites reflects the high degree of covalency of the copper-thiolate bond. 34 refs., 12 figs., 3 tabs

  1. Powder metallurgical high performance materials. Proceedings. Volume 1: high performance P/M metals

    International Nuclear Information System (INIS)

    Kneringer, G.; Roedhammer, P.; Wildner, H.

    2001-01-01

    The proceedings of this sequence of seminars form an impressive chronicle of the continued progress in the understanding of refractory metals and cemented carbides and in their manufacture and application. There the ingenuity and assiduous work of thousands of scientists and engineers striving for progress in the field of powder metallurgy is documented in more than 2000 contributions covering some 30000 pages. The 15th Plansee Seminar was convened under the general theme 'Powder Metallurgical High Performance Materials'. Under this broadened perspective the seminar will strive to look beyond the refractory metals and cemented carbides, which remain at its focus, to novel classes of materials, such as intermetallic compounds, with potential for high temperature applications. (author)

  2. Recovery of molybdenum metal powder from a low grade molybdenite concentrate

    International Nuclear Information System (INIS)

    Mukherjee, T.K.; Menon, P.R.; Shukla, P.P.; Gupta, C.K.

    1988-01-01

    An account is given of the development of a process for the production of molybdenum metal powder from a low grade molybdenite concentrate. The molybdenum value present in the concentrate was leached with a dilute hypochlorite solution generated in-situ by electrolysis of brine solution. The leach liquor was subsequently purified by carbon adsorption process. The leach liquor was chemically processed to recover the molybdenum value in the forms of calcium molybdate and ammonium molybdate salts. These molybdenum intermediates were hydrogen-reduced to metallic molybdenum powder. The experimental set up used, procedure followed and results obtained are discussed and a flowsheet indicating the entire processing scheme is included. 11 refs., 4 figs., 8 tabs

  3. Mechanical properties of metals for biomedical applications using powder metallurgy process: A review

    Science.gov (United States)

    Dewidar, Montasser Marasy; Yoon, Ho-Chel; Lim, Jae Kyoo

    2006-06-01

    The uses of biomaterials have been revolutionizing the biomedical field in deployment as implants for humans. During the past five decades, many implant materials made of metals have been put into practical use. Powder metallurgy techniques have been used to produce controlled porous structures, such as porous coatings applied for dental and orthopedic surgical implants, which allow bony tissue ingrowth within the implant surface, thereby improving fixation. This paper examines various important metals using powder metallurgy technology to produce elements of a total hip replacement. These alloys are 316L stainless steel alloy, Co-Cr-Mo alloy, and Ti-6Al-4V alloy. Also, this paper examines current information on the mechanical properties. Mechanical properties are discussed as a function of type of materials and process of fabrication. This article addresses the engineering aspects concerning the advantages and disadvantages of each type of material.

  4. Experiment Analysis and Modelling of Compaction Behaviour of Ag60Cu30Sn10 Mixed Metal Powders

    Science.gov (United States)

    Zhou, Mengcheng; Huang, Shangyu; Liu, Wei; Lei, Yu; Yan, Shiwei

    2018-03-01

    A novel process method combines powder compaction and sintering was employed to fabricate thin sheets of cadmium-free silver based filler metals, the compaction densification behaviour of Ag60Cu30Sn10 mixed metal powders was investigated experimentally. Based on the equivalent density method, the density-dependent Drucker-Prager Cap (DPC) model was introduced to model the powder compaction behaviour. Various experiment procedures were completed to determine the model parameters. The friction coefficients in lubricated and unlubricated die were experimentally determined. The determined material parameters were validated by experiments and numerical simulation of powder compaction process using a user subroutine (USDFLD) in ABAQUS/Standard. The good agreement between the simulated and experimental results indicates that the determined model parameters are able to describe the compaction behaviour of the multicomponent mixed metal powders, which can be further used for process optimization simulations.

  5. Microporous Titanium through Metal Injection Moulding of Coarse Powder and Surface Modification by Plasma Oxidation

    OpenAIRE

    Shbeh, Mohammed; Yerokhin, Aleksey; Goodall, Russell

    2017-01-01

    Titanium is one of the most attractive materials for biomedical applications due to having excellent biocompatibility accompanied by good corrosion resistance. One popular processing technique for Ti is Metal Injection Moulding (MIM). However, there are several issues associated with the use of this technique, such as the high cost of the fine powder used, the high level of contamination and consequent alteration to material properties, as well as the large volume shrinkage that occurs during...

  6. Melt-drop technique for the production of high-purity metal powder

    International Nuclear Information System (INIS)

    Aldinger, F.; Linck, E.; Claussen, N.

    1977-01-01

    The production of high-purity powders of metals and alloys such as beryllium, titanium alloys, or superalloys is a problem. Oxidation of these materials cannot be avoided. Oxidation occurs in inert gases and even in reducing atmospheres when any gas impurities are present. Therefore, the powder production of these materials has to be performed either in high vacuum or at least in a static atmosphere of inert gas purified immediately before coming into contact with the disintegrating material. These requirements are very well met by the melt-drop technique presented in this paper, especially for coarse powders which must not necessarily be cold-workable. This is true, for example, for superalloys where high-temperature applications require large grain sizes; or in titanium alloys because the final microstructure will be achieved by a thermomechanical treatment. In the case of beryllium and beryllium alloys, where grain sizes <5 μm are desired, further milling is necessary. But the melt-drop technique offers a simple and clean method directly from the purifying process of vacuum melting. In melt-drop processes a liquid metal flows through a nozzle at the bottom of a crucible or the melt is just poured through a sieve. The theory of disintegration of a liquid jet into droplets, dates back to the 19th century. More recent investigations attempted to produce uniformly sized droplets by applying a capillary wave of given wave length to the jet. But this has been done only with non-metallic materials. Evidence is presented to prove the theory and show that this concept is applicable to the production of metal powders with controlled particle size

  7. Direct metal laser deposition of titanium powder Ti-6Al-4V

    Science.gov (United States)

    Bykovskiy, D. P.; Petrovskiy, V. N.; Sergeev, K. L.; Osintsev, A. V.; Dzhumaev, P. S.; Polskiy, V. I.

    2017-12-01

    The paper presents the results of mechanical properties study of the material produced by direct metal laser deposition of VT6 titanium powder. The properties were determined by the results of stretching at tensile testing machine, as well as compared with the properties of the same rolled material. These results show that obtained samples have properties on the level or even higher than that ones of the samples obtained from the rolled material in a certain range of technological regimes.

  8. Towards Production of Additive Manufacturing Grade Metallic Powders on the Battlefield

    Science.gov (United States)

    2017-10-01

    indigenous manufacturing, cold spray technology, manufacturing at the point of need, battle damage repair 16. SECURITY CLASSIFICATION OF: 17...empty brass cartridge casings, medical waste, used batteries, used steel belted off-road tires, etc. [2]). Such an effort should be focused to offer a...this process could produce metallic powder of the following alloys: titanium, high strength steel , tungsten, nickel-base alloys, tool steels

  9. Application of Freeze-Dried Powders of Genetically Engineered Microbial Strains as Adsorbents for Rare Earth Metal Ions.

    Science.gov (United States)

    Moriwaki, Hiroshi; Masuda, Reiko; Yamazaki, Yuki; Horiuchi, Kaoru; Miyashita, Mari; Kasahara, Jun; Tanaka, Tatsuhito; Yamamoto, Hiroki

    2016-10-12

    The adsorption behaviors of the rare earth metal ions onto freeze-dried powders of genetically engineered microbial strains were compared. Cell powders obtained from four kinds of strains, Bacillus subtilis 168 wild type (WT), lipoteichoic acid-defective (ΔLTA), wall teichoic acid-defective (ΔWTA), and cell wall hydrolases-defective (EFKYOJLp) strains, were used as an adsorbent of the rare earth metal ions at pH 3. The adsorption ability of the rare earth metal ions was in the order of EFKYOJLp > WT > ΔLTA > ΔWTA. The order was the same as the order of the phosphorus quantity of the strains. This result indicates that the main adsorption sites for the ions are the phosphate groups and the teichoic acids, LTA and WTA, that contribute to the adsorption of the rare earth metal ions onto the cell walls. The contribution of WTA was clearly greater than that of LTA. Each microbial powder was added to a solution containing 16 kinds of rare earth metal ions, and the removals (%) of each rare earth metal ion were obtained. The scandium ion showed the highest removal (%), while that of the lanthanum ion was the lowest for all the microbial powders. Differences in the distribution coefficients between the kinds of lanthanide ions by the EFKYOJLp and ΔWTA powders were greater than those of the other strains. Therefore, the EFKYOJLp and ΔWTA powders could be applicable for the selective extraction of the lanthanide ions. The ΔLTA powder coagulated by mixing with a rare earth metal ion, although no sedimentation of the WT or ΔWTA powder with a rare earth metal ion was observed under the same conditions. The EFKYOJLp powder was also coagulated, but its flocculating activity was lower than that of ΔLTA. The ΔLTA and EFKYOJLp powders have a long shape compared to those of the WT or ΔWTA strain. The shapes of the cells will play an important role in the sedimentation of the microbial powders with rare earth metal ions. As the results, three kinds of the genetically

  10. Revisiting formic acid decomposition on metallic powder catalysts: Exploding the HCOOH decomposition volcano curve

    Science.gov (United States)

    Tang, Yadan; Roberts, Charles A.; Perkins, Ryan T.; Wachs, Israel E.

    2016-08-01

    This study revisits the classic volcano curve for HCOOH decomposition by metal catalysts by taking a modern catalysis approach. The metal catalysts (Au, Ag, Cu, Pt, Pd, Ni, Rh, Co and Fe) were prepared by H2 reduction of the corresponding metal oxides. The number of surface active sites (Ns) was determined by formic acid chemisorption. In situ IR indicated that both monodentate and bidentate/bridged surface HCOO* were present on the metals. Heats of adsorption (ΔHads) for surface HCOO* values on metals were taken from recently reported DFT calculations. Kinetics for surface HCOO* decomposition (krds) were determined with TPD spectroscopy. Steady-state specific activity (TOF = activity/Ns) for HCOOH decomposition over the metals was calculated from steady-state activity (μmol/g-s) and Ns (μmol/g). Steady-state TOFs for HCOOH decomposition weakly correlated with surface HCOO* decomposition kinetics (krds) and ΔHads of surface HCOO* intermediates. The plot of TOF vs. ΔHads for HCOOH decomposition on metal catalysts does not reproduce the classic volcano curve, but shows that TOF depends on both ΔHads and decomposition kinetics (krds) of surface HCOO* intermediates. This is the first time that the classic catalysis study of HCOOH decomposition on metallic powder catalysts has been repeated since its original publication.

  11. Fabrication of metal matrix composite by semi-solid powder processing

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yufeng [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    Various metal matrix composites (MMCs) are widely used in the automotive, aerospace and electrical industries due to their capability and flexibility in improving the mechanical, thermal and electrical properties of a component. However, current manufacturing technologies may suffer from insufficient process stability and reliability and inadequate economic efficiency and may not be able to satisfy the increasing demands placed on MMCs. Semi-solid powder processing (SPP), a technology that combines traditional powder metallurgy and semi-solid forming methods, has potential to produce MMCs with low cost and high efficiency. In this work, the analytical study and experimental investigation of SPP on the fabrication of MMCs were explored. An analytical model was developed to understand the deformation mechanism of the powder compact in the semi-solid state. The densification behavior of the Al6061 and SiC powder mixtures was investigated with different liquid fractions and SiC volume fractions. The limits of SPP were analyzed in terms of reinforcement phase loading and its impact on the composite microstructure. To explore adoption of new materials, carbon nanotube (CNT) was investigated as a reinforcing material in aluminum matrix using SPP. The process was successfully modeled for the mono-phase powder (Al6061) compaction and the density and density distribution were predicted. The deformation mechanism at low and high liquid fractions was discussed. In addition, the compaction behavior of the ceramic-metal powder mixture was understood, and the SiC loading limit was identified by parametric study. For the fabrication of CNT reinforced Al6061 composite, the mechanical alloying of Al6061-CNT powders was first investigated. A mathematical model was developed to predict the CNT length change during the mechanical alloying process. The effects of mechanical alloying time and processing temperature during SPP were studied on the mechanical, microstructural and

  12. Depositing laser-generated nanoparticles on powders for additive manufacturing of oxide dispersed strengthened alloy parts via laser metal deposition

    Science.gov (United States)

    Streubel, René; Wilms, Markus B.; Doñate-Buendía, Carlos; Weisheit, Andreas; Barcikowski, Stephan; Henrich Schleifenbaum, Johannes; Gökce, Bilal

    2018-04-01

    We present a novel route for the adsorption of pulsed laser-dispersed nanoparticles onto metal powders in aqueous solution without using any binders or surfactants. By electrostatic interaction, we deposit Y2O3 nanoparticles onto iron-chromium based powders and obtain a high dispersion of nano-sized particles on the metallic powders. Within the additively manufactured component, we show that the particle spacing of the oxide inclusion can be adjusted by the initial mass fraction of the adsorbed Y2O3 particles on the micropowder. Thus, our procedure constitutes a robust route for additive manufacturing of oxide dispersion-strengthened alloys via oxide nanoparticles supported on steel micropowders.

  13. Displacement method and apparatus for reducing passivated metal powders and metal oxides

    Science.gov (United States)

    Morrell,; Jonathan S. , Ripley; Edward, B [Knoxville, TN

    2009-05-05

    A method of reducing target metal oxides and passivated metals to their metallic state. A reduction reaction is used, often combined with a flux agent to enhance separation of the reaction products. Thermal energy in the form of conventional furnace, infrared, or microwave heating may be applied in combination with the reduction reaction.

  14. From musket to metallic cartridge a practical history of black powder firearms

    CERN Document Server

    Flatnes, Oyvind

    2013-01-01

    From Musket to Metallic Cartridge is an historical introduction to the use of black powder firearms, from the primitive smooth-bore musket to breech-loading cartridge guns, as well as a primer on their practical use for today's black powder shooters. Drawing on his experience of countless hours on the shooting range, backed up by meticulous research, Oyvind Flatnes relates over 500 years of development and covers the huge range of different ignition systems, models and patents. He describes the use of antique firearms and replicas, discussing their historical and safe modern use. The book is profusely illustrated throughout, with both photographs and diagrams, showing a range of guns and their ammunition, with some live firing shots showing them in action. Aimed at shooters, collectors and general gun and weapons enthusiasts, this book will inspire the reader to learn more about how firearms work, and to take them onto the range too. Superbly illustrated with 265 colour photographs and diagrams.

  15. Facile synthesis of Curcuma longa tuber powder engineered metal nanoparticles for bioimaging applications

    Science.gov (United States)

    Sankar, Renu; Rahman, Pattanathu K. S. M.; Varunkumar, Krishnamoorthy; Anusha, Chidambaram; Kalaiarasi, Arunachalam; Shivashangari, Kanchi Subramanian; Ravikumar, Vilwanathan

    2017-02-01

    Nanomaterials based fluorescent agents are rapidly becoming significant and promising transformative tools for improving medical diagnostics for extensive in vivo imaging modalities. Compared with conventional fluorescent agents, nano-fluorescence has capabilities to improve the in vivo detection and enriched targeting efficiencies. In our laboratory we synthesized fluorescent metal nanoparticles of silver, copper and iron using Curcuma longa tuber powder by simple reduction. The physicochemical properties of the synthesized metal nanoparticles were attained using UV-visible spectrophotometry, scanning electron microscopy with EDAX spectroscopy, dynamic light scattering, Fourier-transform infrared spectroscopy and X-ray diffraction. The Curcuma longa tuber powder has one of the bioactive compound Curcumin might act as a capping agent during the synthesis of nanoparticles. The synthesized metal nanoparticles fluorescence property was confirmed by spectrofluorometry. When compared with copper and iron nanoparticles the silver nanoparticles showed high fluorescence intensity under spectrofluorometry. Moreover, in vitro cell images of the silver nanoparticles in A549 cell lines also correlated with the results of spectrofluorometry. These silver nanoparticles show inspiring cell-imaging applications. They enter into cells without any further modifications, and the fluorescence property can be utilized for fluorescence-based cell imaging applications.

  16. Selective extraction and recovery of rare earth metals from phosphor powders in waste fluorescent lamps using an ionic liquid system.

    Science.gov (United States)

    Yang, Fan; Kubota, Fukiko; Baba, Yuzo; Kamiya, Noriho; Goto, Masahiro

    2013-06-15

    The recycling of rare earth metals from phosphor powders in waste fluorescent lamps by solvent extraction using ionic liquids was studied. Acid leaching of rare earth metals from the waste phosphor powder was examined first. Yttrium (Y) and europium (Eu) dissolved readily in the acid solution; however, the leaching of other rare earth metals required substantial energy input. Ionization of target rare earth metals from the waste phosphor powders into the leach solution was critical for their successful recovery. As a high temperature was required for the complete leaching of all rare earth metals, ionic liquids, for which vapor pressure is negligible, were used as an alternative extracting phase to the conventional organic diluent. An extractant, N, N-dioctyldiglycol amic acid (DODGAA), which was recently developed, showed a high affinity for rare earth metal ions in liquid-liquid extraction although a conventional commercial phosphonic extractant did not. An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Selective extraction and recovery of rare earth metals from phosphor powders in waste fluorescent lamps using an ionic liquid system

    International Nuclear Information System (INIS)

    Yang, Fan; Kubota, Fukiko; Baba, Yuzo; Kamiya, Noriho; Goto, Masahiro

    2013-01-01

    Highlights: • Recycling of rare earth metals from fluorescent lamps was conducted by ionic liquid-mediated extraction. • Acid leaching from a waste phosphor powder was carried out using sulfuric and nitric acids. • An ionic liquid was used as extracting solvent for the rare earth metals. • Selective extraction of rare earth metals from leach solutions was attained. •The extracting ionic liquid phase was recyclable in the recovery process. -- Abstract: The recycling of rare earth metals from phosphor powders in waste fluorescent lamps by solvent extraction using ionic liquids was studied. Acid leaching of rare earth metals from the waste phosphor powder was examined first. Yttrium (Y) and europium (Eu) dissolved readily in the acid solution; however, the leaching of other rare earth metals required substantial energy input. Ionization of target rare earth metals from the waste phosphor powders into the leach solution was critical for their successful recovery. As a high temperature was required for the complete leaching of all rare earth metals, ionic liquids, for which vapor pressure is negligible, were used as an alternative extracting phase to the conventional organic diluent. An extractant, N, N-dioctyldiglycol amic acid (DODGAA), which was recently developed, showed a high affinity for rare earth metal ions in liquid–liquid extraction although a conventional commercial phosphonic extractant did not. An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system

  18. Stochastic hyperfine interactions modeling library

    Science.gov (United States)

    Zacate, Matthew O.; Evenson, William E.

    2011-04-01

    The stochastic hyperfine interactions modeling library (SHIML) provides a set of routines to assist in the development and application of stochastic models of hyperfine interactions. The library provides routines written in the C programming language that (1) read a text description of a model for fluctuating hyperfine fields, (2) set up the Blume matrix, upon which the evolution operator of the system depends, and (3) find the eigenvalues and eigenvectors of the Blume matrix so that theoretical spectra of experimental techniques that measure hyperfine interactions can be calculated. The optimized vector and matrix operations of the BLAS and LAPACK libraries are utilized; however, there was a need to develop supplementary code to find an orthonormal set of (left and right) eigenvectors of complex, non-Hermitian matrices. In addition, example code is provided to illustrate the use of SHIML to generate perturbed angular correlation spectra for the special case of polycrystalline samples when anisotropy terms of higher order than A can be neglected. Program summaryProgram title: SHIML Catalogue identifier: AEIF_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEIF_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU GPL 3 No. of lines in distributed program, including test data, etc.: 8224 No. of bytes in distributed program, including test data, etc.: 312 348 Distribution format: tar.gz Programming language: C Computer: Any Operating system: LINUX, OS X RAM: Varies Classification: 7.4 External routines: TAPP [1], BLAS [2], a C-interface to BLAS [3], and LAPACK [4] Nature of problem: In condensed matter systems, hyperfine methods such as nuclear magnetic resonance (NMR), Mössbauer effect (ME), muon spin rotation (μSR), and perturbed angular correlation spectroscopy (PAC) measure electronic and magnetic structure within Angstroms of nuclear probes through the hyperfine interaction. When

  19. Uranium metal and uranium dioxide powder and pellets - Determination of nitrogen content - Method using ammonia-sensing electrode. 1. ed.

    International Nuclear Information System (INIS)

    1994-01-01

    This International Standard specifies an analytical method for determining the nitrogen content in uranium metal and uranium dioxide powder and pellets. It is applicable to the determination of nitrogen, present as nitride, in uranium metal and uranium dioxide powder and pellets. The concentration range within which the method can be used is between 9 μg and 600 μg of nitrogen per gram. Interference can occur from metals which form complex ammines, but these are not normally present in significant amounts

  20. Microporous Titanium through Metal Injection Moulding of Coarse Powder and Surface Modification by Plasma Oxidation

    Directory of Open Access Journals (Sweden)

    Mohammed Menhal Shbeh

    2017-01-01

    Full Text Available Titanium is one of the most attractive materials for biomedical applications due to having excellent biocompatibility accompanied by good corrosion resistance. One popular processing technique for Ti is Metal Injection Moulding (MIM. However, there are several issues associated with the use of this technique, such as the high cost of the fine powder used, the high level of contamination and consequent alteration to material properties, as well as the large volume shrinkage that occurs during sintering. In this study, the use of a relatively coarse Ti powder with a mean particle size of 75 μm to process Ti parts with the potential for biomedical applications by MIM will be examined, compared to a commercial Ti feedstock, and subsequently coated using Plasma Electrolytic Oxidation (PEO. The results show that samples produced with the coarse powder shrink 35% less and have a relative density 14% less with an average pore size three-times larger than that of the commercial feedstock. This helps increase the potential competitiveness of MIM in the production of biomedical parts, as it reduces cost, shrinkage and results in more intentionally-induced micropores, such as are desired for biomedical implants. PEO treatment of the samples yields a thick rough coating comprised of a mixture of rutile and anatase with interconnected microporous channels and openings resembling the mouth of a volcanic crater.

  1. Artificial neural network modeling of mechanical alloying process for synthesizing of metal matrix nanocomposite powders

    International Nuclear Information System (INIS)

    Dashtbayazi, M.R.; Shokuhfar, A.; Simchi, A.

    2007-01-01

    An artificial neural network model was developed for modeling of the effects of mechanical alloying parameters including milling time, milling speed and ball to powder weight ratio on the characteristics of Al-8 vol%SiC nanocomposite powders. The crystallite size and lattice strain of the aluminum matrix were considered for modeling. This nanostructured nanocomposite powder was synthesized by utilizing planetary high energy ball mill and the required data for training were collected from the experimental results. The characteristics of the particles were determined by X-ray diffraction, scanning and transmission electron microscopy. Two types of neural network architecture, i.e. multi-layer perceptron (MLP) and radial basis function (RBF), were used. The steepest descent along with variable learning rate back-propagation algorithm known as a heuristic technique was utilized for training the MLP network. It was found that MLP network yields better results compared to RBF network, giving an acceptable mapping between the network responses and the target data with a high correlation coefficients. The response surfaces between the response variables, i.e. crystallite size, lattice strain of the aluminum matrix and the processing parameters are presented. The procedure modeling can be used for optimization of the MA process for synthesizing of nanostructured metal matrix nanocomposites

  2. Biological responses of isolated macrophages to cobalt metal and tungsten carbide-cobalt powders.

    Science.gov (United States)

    Lison, D; Lauwerys, R

    1991-10-01

    A previous study from this laboratory, using morphological and biochemical (LDH release) parameters, has shown that tungsten carbide-cobalt dust exhibits a greater cytotoxicity toward isolated macrophages than cobalt metal powder alone. The present study extends this comparison by examining additional biological parameters. Glucose uptake and superoxide anion production by isolated macrophages were significantly more depressed by the tungsten carbide-cobalt mixture (WC-Co) than by cobalt alone (Co) while pure tungsten carbide (WC) had no effect or even stimulated the cells. For glucose-6-phosphate dehydrogenase and cell-associated plasminogen activator (PA) activities, no difference between Co and WC-Co dusts was observed. These observations add further evidence to our previous findings regarding the different biological reactivity of cobalt metal alone or mixed with tungsten carbide.

  3. [Preparation of sub-standard samples and XRF analytical method of powder non-metallic minerals].

    Science.gov (United States)

    Kong, Qin; Chen, Lei; Wang, Ling

    2012-05-01

    In order to solve the problem that standard samples of non-metallic minerals are not satisfactory in practical work by X-ray fluorescence spectrometer (XRF) analysis with pressed powder pellet, a method was studied how to make sub-standard samples according to standard samples of non-metallic minerals and to determine how they can adapt to analysis of mineral powder samples, taking the K-feldspar ore in Ebian-Wudu, Sichuan as an example. Based on the characteristic analysis of K-feldspar ore and the standard samples by X-ray diffraction (XRD) and chemical methods, combined with the principle of the same or similar between the sub-standard samples and unknown samples, the experiment developed the method of preparation of sub-standard samples: both of the two samples above mentioned should have the same kind of minerals and the similar chemical components, adapt mineral processing, and benefit making working curve. Under the optimum experimental conditions, a method for determination of SiO2, Al2O3, Fe2O3, TiO2, CaO, MgO, K2O and Na2O of K-feldspar ore by XRF was established. Thedetermination results are in good agreement with classical chemical methods, which indicates that this method was accurate.

  4. A brief survey of sensing for metal-based powder bed fusion additive manufacturing

    Science.gov (United States)

    Foster, Bryant K.; Reutzel, Edward W.; Nassar, Abdalla R.; Dickman, Corey J.; Hall, Benjamin T.

    2015-05-01

    Purpose - Powder bed fusion additive manufacturing (PBFAM) of metal components has attracted much attention, but the inability to quickly and easily ensure quality has limited its industrial use. Since the technology is currently being investigated for critical engineered components and is largely considered unsuitable for high volume production, traditional statistical quality control methods cannot be readily applied. An alternative strategy for quality control is to monitor the build in real time with a variety of sensing methods and, when possible, to correct any defects as they occur. This article reviews the cause of common defects in powder bed additive manufacturing, briefly surveys process monitoring strategies in the literature, and summarizes recently-developed strategies to monitor part quality during the build process. Design/methodology/approach - Factors that affect part quality in powder bed additive manufacturing are categorized as those influenced by machine variables and those affected by other build attributes. Within each category, multiple process monitoring methods are presented. Findings - A multitude of factors contribute to the overall quality of a part built using PBFAM. Rather than limiting processing to a pre-defined build recipe and assuming complete repeatability, part quality will be ensured by monitoring the process as it occurs and, when possible, altering the process conditions or build plan in real-time. Recent work shows promise in this area and brings us closer to the goal of wide-spread adoption of additive manufacturing technology. Originality/value - This work serves to introduce and define the possible sources of defects and errors in metal-based PBFAM, and surveys sensing and control methods which have recently been investigated to increase overall part quality. Emphasis has been placed on novel developments in the field and their contribution to the understanding of the additive manufacturing process.

  5. High-Temperature Solid Lubricant Coating by Plasma Spraying Using Metal-Metal Clad Powders

    Science.gov (United States)

    Zhang, Tiantian; Lan, Hao; Yu, Shouquan; Huang, Chuanbing; Du, Lingzhong; Zhang, Weigang

    2017-08-01

    NiCr/Ag-Mo composite coating was fabricated by atmospheric plasma spray technology using clad powders as the feedstock. Its tribological properties at variable temperature were evaluated using a ball-on-disk high-temperature tribometer in air. The results showed that compared with NiCr, the NiCr/Ag-Mo composite coating exhibited better lubrication effect and higher wear resistance at all test temperatures, especially above 600 °C. At 800 °C, NiCr/Ag-Mo composite coating showed the lowest friction coefficient of about 0.2 and its corresponding wear rate reached 2.5 × 10-5 mm3/Nm. Characterizations of NiCr/Ag-Mo composite coating revealed that at temperatures below 400 °C, Ag was smeared and spread onto the wear surface, reducing the friction and wear. At temperature above 500 °C, the Ag2MoO4 lubrication film formed by tribo-oxidation significantly improved the coating's lubrication effect and wear resistance.

  6. Net shape fabrication of stainless-steel micro machine components from metallic powder

    International Nuclear Information System (INIS)

    Imbaby, M; Jiang, K; Chang, I

    2008-01-01

    A fabrication process of the net shape 316-L stainless-steel micro machine components is reported. The fabrication process combines softlithography and powder metallurgy to produce microcomponents of complex geometries of high quality. The process starts with softlithography by producing ultra thick SU-8 master moulds and their negative replicas of polydimethylsiloxane (PDMS). Then stainless-steel slurry is prepared by mixing super fine 316-L steel powder and binder to fill the PDMS moulds. The two binders used in the experiments were Duramax D-3005 and a mixture of B1000 and B1007. The PDMS micro moulds are filled with the metallic slurries and green parts are obtained from de-moulding, before going through de-binding and sintering in forming gas atmosphere. The fabrication steps were repeatedly tested. The resultant micro parts show high quality shape retention which is attributed to the quality of the SU-8 master moulds. The hardness property of the sintered microcomponents was tested with a micro indenter and a 200 g load was applied. The Vickers hardness of the sintered components was found to be about 255, which was higher than 225 of annealed 316L stainless steel and the two binders make little difference on the hardness of the sintered samples

  7. Manufacture of hypoeutectic Al-Si metal powders for dispersion matriz in nuclear fuels

    International Nuclear Information System (INIS)

    Raffaeli, H A; Harri, S; Acosta, M; Castillo Guerra, R; Rossi, G; Fabro, J O; Rubiolo, G H

    2012-01-01

    Within the framework of the development of low enriched nuclear fuels for research reactors, U.Mo/Al is the most promising option that has however to be optimized. Indeed at the U.Mo/Al interfaces between U.Mo particles and the Al matrix, an interaction layer grows under irradiation inducing an unacceptable fuel swelling. Adding silicon in limited content into the Al matrix has clearly improved the in-pile fuel behaviour. This breakthrough is attributed to an U.Mo/Al.Si protective layer around U.Mo particles appeared during fuel manufacturing. The present work deals with three techniques applied to produce metal powders of hypoeutectic Al-Si alloys: ball milling, centrifugal atomization and gas atomization. Size and microstructure of the particles are analyzed in the three techniques. The best result is found with the gas atomization system, flakes and rods morphology predominates in the produced powders, with particle sizes below 150 microns and the greater mass population (65%) is between 150 and 125 microns. The particle surface is smooth and the high solidification rate provides a good distribution of the α-Al primary and eutectic phase within each particle (author)

  8. Helium embrittlement of CTR materials simulated by ions implantation and hot isostatic pressing of metal powders

    International Nuclear Information System (INIS)

    Fleischer, L.R.; Spitznagel, J.A.; Choyke, W.J.

    1976-01-01

    Helium embrittlement is currently considered a limitation on the lifetimes of CTR structures exposed to high energy neutrons. The phenomenon has been observed in fast fission reactor irradiated materials and has been studied in helium ion bombarded foil samples. In this study, helium ions were implanted in stainless steel and refractory metal alloy powder particles. The 150 keV ion energies used require particle size distributions with mean particle diameters of about 3 μm to get a suitably homogeneous initial distribution of helium atoms. The helium implanted powders were consolidated by hot isostatic pressing; the helium remained in solid solution. Subsequent thermomechanical processing permitted the preparation of tensile specimens with controlled helium bubble distributions. In general, grain boundary migration concentrated helium bubbles on the boundaries, while conditions favoring stationary boundaries allowed intragranular bubble nucleation on dislocations. It remains to be seen whether the distributions available through these processes are representative of those that will be generated in situ by (n,α) reactions in CTR neutron spectra. Specimens for bulk properties measurements prepared in this way are most suitable for study of helium embrittlement as an isolated effect. Many of the constraints encountered in other sample preparation methods are mitigated

  9. Contact-Free Support Structures for Part Overhangs in Powder-Bed Metal Additive Manufacturing

    Directory of Open Access Journals (Sweden)

    Kenneth Cooper

    2017-12-01

    Full Text Available This study investigates the feasibility of a novel concept, contact-free support structures, for part overhangs in powder-bed metal additive manufacturing. The intent is to develop alternative support designs that require no or little post-processing, and yet, maintain effectiveness in minimizing overhang distortions. The idea is to build, simultaneously during part fabrications, a heat sink (called “heat support”, underneath an overhang to alter adverse thermal behaviors. Thermomechanical modeling and simulations using finite element analysis were applied to numerically research the heat support effect on overhang distortions. Experimentally, a powder-bed electron beam additive manufacturing system was utilized to fabricate heat support designs and examine their functions. The results prove the concept and demonstrate the effectiveness of contact-free heat supports. Moreover, the method was tested with different heat support parameters and applied to various overhang geometries. It is concluded that the heat support proposed has the potential to be implemented in industrial applications.

  10. Synchrotron hard X-ray imaging of shock-compressed metal powders

    Science.gov (United States)

    Rutherford, Michael E.; Chapman, David J.; Collinson, Mark A.; Jones, David R.; Music, Jasmina; Stafford, Samuel J. P.; Tear, Gareth R.; White, Thomas G.; Winters, John B. R.; Drakopoulos, Michael; Eakins, Daniel E.

    2015-06-01

    This poster will present the application of a new, high-energy (50 to 250 keV) synchrotron X-ray radiography technique to the study of shock-compressed granular materials. Following plate-impact loading, transmission radiography was used to quantitatively observe the compaction and release processes in a range of high-Z metal powders (e.g. Fe, Ni, Cu). By comparing the predictions of 3D numerical models initialized from X-ray tomograms-captured prior to loading-with experimental results, this research represents a new approach to refining mesoscopic compaction models. The authors gratefully acknowledge the ongoing support of Imperial College London, EPSRC, STFC and the Diamond Light Source, and AWE Plc.

  11. Using Laser Ultrasound to Detect Subsurface Defects in Metal Laser Powder Bed Fusion Components

    Science.gov (United States)

    Everton, Sarah; Dickens, Phill; Tuck, Chris; Dutton, Ben

    2018-03-01

    Laser powder bed fusion offers many advantages over conventional manufacturing methods, such as the integration of multiple parts that can result in significant weight-savings. The increased design freedom that layer-wise manufacture allows has also been seen to enhance component performance at little or no added cost. For such benefits to be realized, however, the material quality must first be assured. Laser ultrasonic testing is a noncontact inspection technique that has been proposed as suitable for in situ monitoring of metal additive manufacturing processes. This article explores the current capability of this technique to detect manufactured, subsurface defects in Ti-6Al-4V samples, ex situ. The results are compared with x-ray computed tomography reconstructions and focus variation microscopy. Although laser ultrasound has been used to identify material discontinuities, further work is required before this technique could be implemented in situ.

  12. Feature-based characterisation of signature topography in laser powder bed fusion of metals

    Science.gov (United States)

    Senin, Nicola; Thompson, Adam; Leach, Richard

    2018-04-01

    The use of state-of-the-art areal topography measurement instrumentation allows for a high level of detail in the acquisition of topographic information at micrometric scales. The 3D geometric models of surface topography obtained from measured data create new opportunities for the investigation of manufacturing processes through characterisation of the surfaces of manufactured parts. Conventional methods for quantitative assessment of topography usually only involve the computation of texture parameters, summary indicators of topography-related characteristics that are computed over the investigated area. However, further useful information may be obtained through characterisation of signature topographic formations, as more direct indicators of manufacturing process behaviour and performance. In this work, laser powder bed fusion of metals is considered. An original algorithmic method is proposed to isolate relevant topographic formations and to quantify their dimensional and geometric properties, using areal topography data acquired by state-of-the-art areal topography measurement instrumentation.

  13. Use of Cold Gas Dynamic Spraying of bi-metallic powder mixtures as alternative to classic powder metallurgy route for producing intermetallic materials

    Directory of Open Access Journals (Sweden)

    Vit Jan

    2016-06-01

    Full Text Available The paper presents cold gas dynamic spraying (or Cold Spray as a novel surface treatment technology capable not only of surface modifications but also being used as bulk creating technology. This is demonstrated on numerous samples where bi-metallic powder feedstock is deposited into bulk, self-standing pieces of material that does not need the support of substrate. Mixtures from the group of Fe, Al, Ti, Ni, Cu were used for the initial bi-metallic mixtures. The deposited samples were then subjected to annealing at temperatures ranging from 300 to 1100°C in protective atmosphere and resulting morphologies and microstructures were analysed. Generally materials with high proportion of intermetallic phase content were obtained. These are discussed as potential scaffolds for metal or polymer matrix composites or as hi temperature resistive supports for catalysts with filter functions.

  14. Features of the estimation of temperature distribution on the bead formed by the laser aided metal powder deposition

    Science.gov (United States)

    Zavalov, Yuri N.; Dubrov, Alexander V.; Mirzade, Fikret Kh.; Dubrov, Vladimir D.

    2017-06-01

    The estimation of temperature variations in five regions of layer track is fulfilled in two different cases of layer track formation: laser aided metal powder deposition and selective laser melting with a pre-deposited layer of metal powder. The peculiarities of the multichannel pyrometer have been described, and the advantages of the application of spectralratio pyrometer in diagnostics in the additive laser technologies have been demonstrated. A set of measurements of the temperature distribution in the region of exposure to laser radiation during a bead formation in technology of laser aided metal powder deposition with powder injection has been performed at the specific energy input of J=90 MJ/kg. The dependences of the temperature on scanning velocity, laser power and powder thickness have been derived in the technology of selective laser melting. It has been shown that the maximum temperature of the track surface is little changed in the wide range of variation of the calculated parameter of specific energy input J=4…20 MJ/kg, the bead width is here increased as J grows. The increase of J above a certain value J0 leads to a rise in the temperature at the bead axis. For the experimental conditions with the track width around 1 mm, the character value is estimated as J0 = 24 MJ/kg. It has been shown that J0 depends inversely on the track width.

  15. Influence of a Passivated Nanodimensional Aluminum Powder on Physical and Chemical Characteristics of Combustion of Metal Compositions

    Science.gov (United States)

    Komarova, M. V.; Vorozhtsov, A. B.

    2014-11-01

    The influence of various nanodimensional metal powders on the linear combustion rate of metal compositions is analyzed. It is demonstrated that passivation of nanoaluminum with glycine not only provides its physical and chemical compatibility with other components of a high-energy material and its subsequent physical and chemical stability, but also does not influence the main integral combustion characteristic that opens possibilities for its application as a fuel in high-energy compositions.

  16. A more efficient way to shape metal-organic framework (MOF) powder materials for hydrogen storage applications

    CSIR Research Space (South Africa)

    Ren, Jianwei

    2015-04-01

    Full Text Available of Hydrogen Energy Vol. 40(13) A more efficient way to shape metal-organic framework (MOF) powder materials for hydrogen storage applications Jianwei Ren*, Nicholas M. Musyoka, Henrietta W. Langmi, Ashton Swartbooi, Brian C. North, Mkhulu Mathe Hy...

  17. (YSZ) powders

    Indian Academy of Sciences (India)

    Unknown

    Keywords. YSZ powder; dispersion behaviour; grindability. 1. Introduction. During the synthesis of oxide powders by solution based techniques (e.g. solution combustion, decomposition of metal nitrates, precipitation etc), agglomerates of fine crystallites of the precursors or oxides form and their size vary up to many microns.

  18. Hyperfine interactions of 57Fe implanted in solids studied by conversion electron Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Sawicka, B.D.

    1978-01-01

    The hyperfine interactions of stable 57 Fe nuclei implanted in various matrices were studied using conversion electron Moessbauer spectroscopy. The results obtained for 57 Fe implanted in aluminium in d-metals in silicon and germanium are presented. The properties of the implantation produced materials and the lattice location of iron impurities are discussed. The information concerning the volume dependence of the hyperfine interactions and the origin of the electric field gradients in solids were obtained. (author)

  19. Process defects and in situ monitoring methods in metal powder bed fusion: a review

    Science.gov (United States)

    Grasso, Marco; Colosimo, Bianca Maria

    2017-04-01

    Despite continuous technological enhancements of metal Additive Manufacturing (AM) systems, the lack of process repeatability and stability still represents a barrier for the industrial breakthrough. The most relevant metal AM applications currently involve industrial sectors (e.g. aerospace and bio-medical) where defects avoidance is fundamental. Because of this, there is the need to develop novel in situ monitoring tools able to keep under control the stability of the process on a layer-by-layer basis, and to detect the onset of defects as soon as possible. On the one hand, AM systems must be equipped with in situ sensing devices able to measure relevant quantities during the process, a.k.a. process signatures. On the other hand, in-process data analytics and statistical monitoring techniques are required to detect and localize the defects in an automated way. This paper reviews the literature and the commercial tools for in situ monitoring of powder bed fusion (PBF) processes. It explores the different categories of defects and their main causes, the most relevant process signatures and the in situ sensing approaches proposed so far. Particular attention is devoted to the development of automated defect detection rules and the study of process control strategies, which represent two critical fields for the development of future smart PBF systems.

  20. Proton hyperfine tensors in nitroxide radicals

    Energy Technology Data Exchange (ETDEWEB)

    Brustolon, M.; Maniero, A.L.; Segre, U. (Universita di Padova (Italy)); Ottaviani, M.F. (Universita di Firenze (Italy)); Romanelli, M. (Universita della Basilicata (Italy))

    1990-08-23

    The proton hyperfine tensors of five nitroxide radicals have been obtained by ENDOR spectroscopy in frozen solution. The spectra are interpreted by computing the dipolar hyperfine interaction and simulating the spectra. EPR spectra in solution of the same radicals have been simulated by taking into account the effects of the proton hyperfine tensors. We have been able to reproduce accurately the line broadening effects of the proton hyperfine structures inside each nitrogen hyperfine component and we have determined the correlation times for the rotational motion. In the case of the radical Tempol, our analysis allows discrimination between the effects due to the protons of the axial and equatorial methyl groups. On the basis of experimental evidence we can attribute the larger isotropic hyperfine coupling constant to the axial methyl protons. The possible use of the present results for interpreting the spectra of other nitroxide radicals is discussed.

  1. Formation of Nanoscale Metallic Glassy Particle Reinforced Al-Based Composite Powders by High-Energy Milling

    Directory of Open Access Journals (Sweden)

    Weiwen Zhang

    2017-10-01

    Full Text Available The initial microstructure and mechanical properties of composite powders have a vital role in determining the microstructure and mechanical properties of the subsequent consolidated bulk composites. In this work, Al-based matrix composite powders with a dense and uniform distribution of metallic glass nanoparticles were obtained by high-energy milling. The results show that high-energy milling is an effective method for varying the microstructure and mechanical properties of the composite powders, thereby offering the ability to control the final microstructure and properties of the bulk composites. It was found that the composite powders show a deformed layer combined with an undeformed core after milling. The reinforcements, metallic glass microparticles, are fractured into dense distributed nanoparticles in the deformed layer, owing to the severe plastic deformation, while in the undeformed core, the metallic glass microparticles are maintained. Therefore, a bimodal structure was obtained, showing a mechanical bimodal structure that has much higher hardness in the outer layer than the center core. The hardness of the composite particles increases significantly with increasing milling time, due to dispersion strengthening and work hardening.

  2. The choice of the conditions to receive the electrolytic zinc powders for metal-rich compositions

    Directory of Open Access Journals (Sweden)

    A. V. Patrushev

    2015-03-01

    Full Text Available In the work a method of obtaining highly dispersed zinc powders by electrolysis and comparison of the properties of zinc-rich compositions prepared using as a pigment zinc powders obtained by different methods is provided. Conducted measurements have shown that the electrical conductivity of zinc-rich coatings comprising electrolytic zinc powder does not inferior to the conductivity of the film with PZHD-0 powder obtained by the  evaporation-condensation method, despite the significant difference in the amount of zinc pigment. On the basis of the received data one can conclude that the use of electrolytic zinc powder as a pigment will significantly save zinc.

  3. Metal release from stainless steel powders and massive sheets--comparison and implication for risk assessment of alloys.

    Science.gov (United States)

    Hedberg, Yolanda; Mazinanian, Neda; Odnevall Wallinder, Inger

    2013-02-01

    Industries that place metal and alloy products on the market are required to demonstrate that they are safe for all intended uses, and that any risks to humans, animals or the environment are adequately controlled. This requires reliable and robust in vitro test procedures. The aim of this study is to compare the release of alloy constituents from stainless steel powders of different grades (focus on AISI 316L) and production routes into synthetic body fluids with the release of the same metals from massive sheets in relation to material and surface characteristics. The comparison is justified by the fact that the difference between massive surfaces and powders from a metal release/dissolution and surface perspective is not clearly elucidated within current legislations. Powders and abraded and aged (24 h) massive sheets were exposed to synthetic solutions of relevance for biological settings and human exposure routes, for periods of up to one week. Concentrations of released iron, chromium, nickel, and manganese in solution were measured, and the effect of solution pH, acidity, complexation capacity, and proteins elucidated in relation to surface oxide composition and its properties. Implications for risk assessments based on in vitro metal release data from alloys are elucidated.

  4. Fabrication and characterization of graded impedance impactors for gas gun experiments from tape cast metal powders

    International Nuclear Information System (INIS)

    Martin, L. Peter; Orlikowski, Daniel; Nguyen, Jeffrey H.

    2006-01-01

    Fabrication of compositionally graded structures for use as light-gas gun impactors has been demonstrated using a tape casting technique. Mixtures of metal powders in the Mg-Cu system were cast into a series of tapes with uniform compositions ranging from 100% Mg to 100% Cu. The individual compositions were fabricated into monolithic pellets for characterization by laminating multiple layers together, thermally removing the organics, and hot-pressing to near-full density. The pellets were characterized by optical and scanning electron microscopy, X-ray diffraction, and measurement of density and sound wave velocity. The density and acoustic impedance were observed to vary monotonically (and nearly linearly) with composition. Graded structures were fabricated by stacking layers of different compositions in a sequence calculated to yield a desired acoustic impedance profile. The measured physical properties of the graded structures compare favorably with those predicted from the monolithic pellet characteristics. Fabrication of graded impactors by this technique is of significant interest for providing improved control of the pressure profile and impactor planarity in gas gun experiments

  5. Critical exponent β for hyperfine fields in nickel

    International Nuclear Information System (INIS)

    Bleck, J.; Butt, R.; Michaelsen, R.; Rosenblum, S.S.; Zeitz, W.D.; Freie Univ. Berlin

    1977-01-01

    The magnetic hyperfine fields for 63 Ni, 66 Cu, and 67 Zn nuclei in nickel metal have been measured by means of perturbed γ-ray angular distribution techniques at different temperatures up to 1 K below the Curie temperature, Tsub(c). The temperature dependence of the fields can be very well fitted by (1-T/Tsub(c))sup(β) with best values β = 0.322(16) for 63 NiNi, β = 0.427(42) for 66 CuNi, and β = 0.427(14) for 67 ZnNi. The differences between these exponents indicate that there could be probe atom dependent deviations from proportionality between hyperfine field and bulk magnetization in the critical region. (orig.) [de

  6. Hydrogen molecule binding to unsaturated metal sites in metal-organic frameworks studied by neutron powder diffraction and inelastic neutron scattering

    Science.gov (United States)

    Liu, Yun; Brown, Craig; Neumann, Dan; Dinca, Mircea; Long, Jeffrey; Peterson, Vanessa; Kepert, Cameron

    2007-03-01

    Metal organic framework (MOF) materials have shown considerable potential for hydrogen storage arising from very large surface areas. However, the low binding energy of hydrogen molecules limits its storage capability to very low temperatures (industrial applications. Using neutron powder diffraction (NPD), we have characterized the hydrogen adsorption sites in a selected series of MOF materials with exposed unsaturated metal ions. Direct binding between the unsaturated metal ions and hydrogen molecules is observed and responsible for the enhanced initial hydrogen adsorption enthalpy. The different metals centers in these MOFs show different binding strength and interaction distances between the hydrogen molecule and metal ions. The organic linker also affects the overall H2 binding strength. Inelastic neutron scattering spectra of H2 in these MOFs are also discussed.

  7. Obtainment, machining and wear of metal matrix composites processed by powder metallurgy

    International Nuclear Information System (INIS)

    Jesus, Edilson Rosa Barbosa de.

    1998-01-01

    The aim of this investigation was the obtainment of metal matrix composites (MMC) by the route of powder metallurgy, and the valuation of these materials with relation to their machining and wear characteristics. Firstly, were obtained pure commercial aluminium matrix composites materials, with 5, 10 and 15% volumetric fraction of silicon carbide particles. Was also obtained a material without reinforcement particles in order to verify by comparison, the influence of addition of reinforcement particles. The obtained materials were characterized physics (hydrostatic density), mechanics (hardness and tensile tests) and microstructurally (optical microscopy and scanning electron microscopy). The results showed a homogeneous distribution of reinforcement particles in the composite, and improvement in the mechanical properties, mainly tensile strength (UTS) in comparison to the unreinforced material. After, tests were made to verify the materials behavior during machining and to check the performance of several tool materials (cemented carbide, ceramics and polycrystalline diamond). In these tests, values of the cutting force were measured by instrumented tool-holders. Phenomena such as tool wear, built-up edge formation and mechanism of chip formation were also observed and evaluated. The results from the cemented carbide tool tests, were utilised for the machinability index determination of each material. These results were applied to the Taylor equation and the equation constants for each material and test conditions were determined. The results showed that the inclusion of silicon carbide particles made extremely difficult the machining of the composites, and only with diamond tool, satisfactory results were obtained. At last, wear tests were performed to verify the influence of the reinforcement particles in the characteristics of wear resistance of the materials. The results obtained were utilized in the wear coefficient determination for each material. The

  8. Exploration on Wire Discharge Machining Added Powder for Metal-Based Diamond Grinding Wheel on Wire EDM Dressing and Truing of Grinding Tungsten Carbide Material

    Science.gov (United States)

    Chow, H. M.; Yang, L. D.; Lin, Y. C.; Lin, C. L.

    2017-12-01

    In this paper, the effects of material removal rate and abrasive grain protrusion on the metal-based diamond grinding wheel were studied to find the optimal parameters for adding powder and wire discharge. In addition, this kind of electric discharge method to add powder on the metal-based diamond grinding wheel on line after dressing and truing will be applied on tungsten carbide to study the grinding material removal rate, grinding wheel wear, surface roughness, and surface micro-hardness.

  9. Metal-Matrix Hardmetal/Cermet Reinforced Composite Powders for Thermal Spray

    Directory of Open Access Journals (Sweden)

    Dmitri GOLJANDIN

    2012-03-01

    Full Text Available Recycling of materials is becoming increasingly important as industry response to public demands, that resources must be preserved and environment protected. To produce materials competitive in cost with primary product, secondary producers have to pursue new technologies and other innovations. For these purposes different recycling technologies for composite materials (oxidation, milling, remelting etc are widely used. The current paper studies hardmetal/cermet powders produced by mechanical milling technology. The following composite materials were studied: Cr3C2-Ni cermets and WC-Co hardmetal. Different disintegrator milling systems for production of powders with determined size and shape were used. Chemical composition of produced powders was analysed.  To estimate the properties of recycled hardmetal/cermet powders, sieving analysis, laser granulometry and angularity study were conducted. To describe the angularity of milled powders, spike parameter–quadric fit (SPQ was used and experiments for determination of SPQ sensitivity and precision to characterize particles angularity were performed. Images used for calculating SPQ were taken by SEM processed with Omnimet Image Analyser 22. The graphs of grindability and angularity were composed. Composite powders based on Fe- and Ni-self-fluxing alloys for thermal spray (plasma and HVOF were produced. Technological properties of powders and properties of thermal sprayed coatings from studied powders were investigated. The properties of spray powders reinforced with recycled hardmetal and cermet particles as alternatives for cost-sensitive applications were demonstrated.DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1348

  10. Analysis of powdered tungsten carbide hard-metal precursors and cemented compact tungsten carbides using laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Novotny, K. [Laboratory of Atomic Spectrochemistry, Department of Chemistry, Faculty of Science, Masaryk University, Kotlarska 2, 611 37 Brno (Czech Republic)], E-mail: codl@sci.muni.cz; Stankova, A. [Laboratory of Atomic Spectrochemistry, Department of Chemistry, Faculty of Science, Masaryk University, Kotlarska 2, 611 37 Brno (Czech Republic); Haekkaenen, H.; Korppi-Tommola, J. [Department of Chemistry, University of Jyvaeskylae, P.O. BOX 35, FIN-40014 (Finland); Otruba, V.; Kanicky, V. [Laboratory of Atomic Spectrochemistry, Department of Chemistry, Faculty of Science, Masaryk University, Kotlarska 2, 611 37 Brno (Czech Republic)

    2007-12-15

    Laser-induced breakdown spectroscopy (LIBS) has been applied to the direct analysis of powdered tungsten carbide hard-metal precursors and cemented tungsten carbides. The aim of this work was to examine the possibility of quantitative determination of the niobium, titanium, tantalum and cobalt. The investigated samples were in the form of pellets, pressed with and without binder (powdered silver) and in the form of cemented tungsten carbides. The pellets were prepared by pressing the powdered material in a hydraulic press. Cemented tungsten carbides were embedded in resin for easier manipulation. Several lasers and detection systems were utilized. The Nd:YAG laser working at a basic wavelength of 1064 nm and fourth-harmonic frequency of 266 nm with a gated photomultiplier or ICCD detector HORIBA JY was used for the determination of niobium which was chosen as a model element. Different types of surrounding gases (air, He, Ar) were investigated for analysis. The ICCD detector DICAM PRO with Mechelle 7500 spectrometer with ArF laser (193 nm) and KrF laser (248 nm) were employed for the determination of niobium, titanium, tantalum and cobalt in samples under air atmosphere. Good calibration curves were obtained for Nb, Ti, and Ta (coefficients of determination r{sup 2} > 0.96). Acceptable calibration curves were acquired for the determination of cobalt (coefficient of determination r{sup 2} = 0.7994) but only for the cemented samples. In the case of powdered carbide precursors, the calibration for cobalt was found to be problematic.

  11. Evaluation of a carbon fibre powder scraper used in metal additive manufacturing

    CSIR Research Space (South Africa)

    Bester, Duwan C

    2017-11-01

    Full Text Available by the powder scraper was sufficient or not. The quality of the powder layer refers to the flatness (surface roughness) of the layer. Therefore, the research objectives are:  Devise a method for a quantitative evaluation of the performance of a powder... into one Excel file and then processed. The performance of the scrapers were given in the number of peaks that fell out of specification. In this case, the specification was that defects or peaks should be smaller than one-and-a-half times the thickness...

  12. Mechanical stimulated reaction of metal/polymer mixed powders; Kinzoku/kobunshi kongo funmatsu no kikaiteki reiki hanno

    Energy Technology Data Exchange (ETDEWEB)

    Tobita, M.; Sakakibara, A.; Takemoto, Y. [Okayama University, Okayama (Japan). Faculty of Engineering; Iwabu, H. [Kurare Co. Ltd., Osaka (Japan)

    1999-12-15

    Mechanical grinding (MG) with mechanically stimulated reaction was performed on metal/polymer mixed powders. The starting materials used in this study were the metals of Mg, Ti and Mg{sub 2}Ni powders, arid polymer of PTFE, PVC and PE powders. The MG process was investigated using XRD, IR, SEM and TEM. According to XRD results, magnesium fluoride (MgF{sub 2}, TiF{sub 2}) and chloride (MgCl{sub 2}) were detected from MG products of the Mg/PTFE, Ti/PTFE and Mg/PVC blending systems, respectively. Explosive reaction was found during MG of both Mg/PTFE and Ti/PTFE. It was also confirmed by XRD results that the production of MgF{sub 2} had already been formed just before the explosive reaction in Mg/PTFE system. It was found from IR analysis that C-C single bond in the polymers, not only both in PTFE and PVC but also in PE, changed to double bond C=C. Hydrogen produced due to decomposition of PE on blending Mg{sub 2}Ni/PE was absorbed into C-Mg{sub 2}Ni-H as amorphous solutes. These mechanically stimulated reaction was powerful method for decomposition of engineering plastics. (author)

  13. New titrimetric method for oxygen to metal ratio in uranium oxide powders

    International Nuclear Information System (INIS)

    Ray, Vinod Kumar; Brahmananda Reddy, G.; Balaji Rao, Y.; Subba Rao, Y.

    2015-01-01

    O/U ratio is of high importance to both U 3 O 8 and UO 2 powders for different reasons. In UO 2 powder it is a guiding parameter for sintering process where as for U 3 O 8 , it indicates efficiency of ammonium di-uranate (ADU) to U 3 O 8 conversion process. In the present method for O/U determination, UO 2 and U 3 O 8 powders are dissolved in 4.5 M sulphuric acid and little HF by heating on hot plate. Subsequently, optimized quantity of phosphoric acid is added on cooling, for getting sharp end point. The resultant solution is titrated with standard potassium dichromate using barium diphenylamine sulphonate (BDS) as an indicator. The expanded uncertainties calculated for UO 2 and U 3 O 8 powders are ±0.004 and ±0.006 O/U ratio units respectively at 95 % confidence level. (author)

  14. Multiphysics simulation of thermal phenomena in direct laser metal powder deposition

    CSIR Research Space (South Africa)

    Pityana, SL

    2016-11-01

    Full Text Available presents on two dimensional multi-physics models to describe the physical mechanism of heat transfer, melting and solidification that take place during and post laser-powder interaction. The simulated transient temperature profile, the geometrical features...

  15. EFFECTIVE HYPERFINE-STRUCTURE FUNCTIONS OF AMMONIA

    International Nuclear Information System (INIS)

    Augustovičová, L.; Soldán, P.; Špirko, V.

    2016-01-01

    The hyperfine structure of the rotation-inversion ( v 2 = 0 + , 0 − , 1 + , 1 − ) states of the 14 NH 3 and 15 NH 3 ammonia isotopomers is rationalized in terms of effective (ro-inversional) hyperfine-structure (hfs) functions. These are determined by fitting to available experimental data using the Hougen’s effective hyperfine-structure Hamiltonian within the framework of the non-rigid inverter theory. Involving only a moderate number of mass independent fitting parameters, the fitted hfs functions provide a fairly close reproduction of a large majority of available experimental data, thus evidencing adequacy of these functions for reliable prediction. In future experiments, this may help us derive spectroscopic constants of observed inversion and rotation-inversion transitions deperturbed from hyperfine effects. The deperturbed band centers of ammonia come to the forefront of fundamental physics especially as the probes of a variable proton-to-electron mass ratio.

  16. Investigation of the powder loading of gas-atomized Ti6Al4V powder using an ‘in-house’ binder for metal injection moulding

    CSIR Research Space (South Africa)

    Seerane, MN

    2013-10-01

    Full Text Available choice for applications such as watch parts, medical devices/implants and dental components, and sports goods. These parts can be made with powder metallurgy processes such as MIM. In MIM the powder loading, i.e. the ratio of the powder to the binder...

  17. Control of inhomogeneous atomic ensembles of hyperfine qudits

    DEFF Research Database (Denmark)

    Mischuck, Brian Edward; Merkel, Seth T.; Deutsch, Ivan H.

    2012-01-01

    We study the ability to control d-dimensional quantum systems (qudits) encoded in the hyperfine spin of alkali-metal atoms through the application of radio- and microwave-frequency magnetic fields in the presence of inhomogeneities in amplitude and detuning. Such a capability is essential...... to the design of robust pulses that mitigate the effects of experimental uncertainty and also for application to tomographic addressing of particular members of an extended ensemble. We study the problem of preparing an arbitrary state in the Hilbert space from an initial fiducial state. We prove...

  18. Fabrication of metallic alloy powder (Ni{sub 3}Fe) from Fe–77Ni scrap

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Inseok [ES Materials Research Center, Research Institute of Industrial Science and Technology, Incheon 406-840 (Korea, Republic of); Shin, Shun-Myung [Extractive Metallurgy Department, Korea Institute of Geoscience and Mineral Resources, Deajeon 305-350 (Korea, Republic of); Ha, Sang-An [Department of Environmental Engineering, Silla University, Busan 46958 (Korea, Republic of); Wang, Jei-Pil, E-mail: jpwang@pknu.ac.kr [Department of Metallurgical Engineering, Pukyong National University, Busan 608-739 (Korea, Republic of)

    2016-06-15

    The oxidation behavior of Fe–77Ni alloy scrap was investigated at an oxygen partial pressure of 0.2 atm and temperatures ranging from 400 °C to 900 °C. The corresponding oxidation rate increased with increasing temperature and obeyed the parabolic rate law, as evidenced by its linear proportionality to the temperature. In addition, surface morphologies, cross-sectional views, compositions, structural properties were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Diffusion through either the spinel structure or the NiO layer, which were both present in the alloy during oxidation at elevated temperatures, was deemed the rate-limiting step of the reaction. The oxide powder less than 10 μm was obtained from Fe–77Ni alloy scrap was obtained using ball-milling and sieving processes. In fact, 15 h of milling yielded a recovery ratio of 97%. Using hydrogen gas, the oxide powder was successfully reduced to an alloy powder of Ni{sub 3}Fe and reduction rates of ∼97% were achieved after 3 h at 1000 °C. - Highlights: • The oxidation behavior of Fe–77Ni alloy scrap was investigated. • The oxide powder less than 10 μm was obtained from Fe–77Ni alloy scrap. • Using hydrogen gas, the oxide powder was successfully reclaimed. • Reduction rates of ∼97% were achieved after 3 h at 1000 °C.

  19. Ultrasonic evaluation of the morphological characteristics of metallic powders in the context of mechanical alloying.

    Science.gov (United States)

    Barguet, L; Pezerat, C; Bentahar, M; El Guerjouma, R; Tournat, V

    2015-07-01

    An ultrasonic method is proposed to characterize the morphological (geometrical) aspects of powders through the elastic modulus dependence of their packing on the factors of polydispersity, coordination number and particle shape. During the mechanical alloying process, the variation in geometrical characteristics of powders provides critical information. Ultrasonic parameters are shown to be sensitive not only to the average contact number per bead (i.e. the coordination number) but also to characteristics of the bead size distribution, when given the same sample preparation and confining pressure. These parameters, in turn, are sensitive to both the granular medium polydispersity and particle shapes. A non-monotonic behavior of the ultrasonic velocity (and of the derived compressional wave modulus) is observed throughout the alloying process, which thus offers possibilities for powder structure monitoring. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Analysis of Hazards Associated with a Process Involving Uranium Metal and Uranium Hydride Powders

    Energy Technology Data Exchange (ETDEWEB)

    Bullock, J.S.

    2000-05-01

    An analysis of the reaction chemistry and operational factors associated with processing uranium and uranium hydride powders is presented, focusing on a specific operation in the Development Division which was subjected to the Job Hazard Analysis (JHA) process. Primary emphasis is on the thermodynamic factors leading to pyrophoricity in common atmospheres. The discussion covers feed powders, cold-pressed and hot-pressed materials, and stray material resulting from the operations. The sensitivity of the various forms of material to pyrophoricity in common atmospheres is discussed. Operational recommendations for performing the work described are given.

  1. Measurement of loose powder density

    International Nuclear Information System (INIS)

    Akhtar, S.; Ali, A.; Haider, A.; Farooque, M.

    2011-01-01

    Powder metallurgy is a conventional technique for making engineering articles from powders. Main objective is to produce final products with the highest possible uniform density, which depends on the initial loose powder characteristics. Producing, handling, characterizing and compacting materials in loose powder form are part of the manufacturing processes. Density of loose metallic or ceramic powder is an important parameter for die design. Loose powder density is required for calculating the exact mass of powder to fill the die cavity for producing intended green density of the powder compact. To fulfill this requirement of powder metallurgical processing, a loose powder density meter as per ASTM standards is designed and fabricated for measurement of density. The density of free flowing metallic powders can be determined using Hall flow meter funnel and density cup of 25 cm/sup 3/ volume. Density of metal powders like cobalt, manganese, spherical bronze and pure iron is measured and results are obtained with 99.9% accuracy. (author)

  2. Toxic metal levels in cocoa powder and chocolate by ICP-MS method after microwave-assisted digestion.

    Science.gov (United States)

    Lo Dico, Gianluigi Maria; Galvano, Fabio; Dugo, Giacomo; D'ascenzi, Carlo; Macaluso, Andrea; Vella, Antonio; Giangrosso, Giuseppe; Cammilleri, Gaetano; Ferrantelli, Vincenzo

    2018-04-15

    The Commission Regulation (EC) Regulation N. 488/2014, established the concentration limits for cadmium in specific products based on cocoa and chocolate products as from January 2019. Based on this information there is a need to determine ultratrace levels of elements that might be presents in cocoa and chocolate products. In this work, the concentrations of Arsenic, Antimony, Cadmium, Chromium, Lead, Selenium and Vanadium were evaluated in cocoa powder and chocolate by the validation of an ICP-MS method. Good selectivity/specificity, recovery, repeatability and within-laboratory reproducibility, LOD, LOQ, range of linearity, standard measurement uncertainty parameters for method validation were achieved, in accordance with Commission Regulation. The cocoa powder revealed the maximum metal concentrations of 0.303 ± 0.035 mg/kg for cadmium, 1.228 ± 0.146 mg/kg for lead and 0.094 ± 0.013 mg/kg for arsenic. A significant difference was found between cocoa powder and chocolate samples (p < .05). Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Direct laser metal deposition of WC/Co/Cr powder by means of the functionally graded materials strategy

    Science.gov (United States)

    Angelastro, A.; Campanelli, S. L.

    2017-12-01

    One of the many applications of direct laser metal deposition (DLMD) is the realization of multilayer thick coatings having particular mechanical characteristics, such as high hardness. The objective of this work was to obtain a thick, very hard and wear resistant coating, containing a high percentage of tungsten carbide (WC), on an AISI 304 stainless steel substrate. In order to achieve this result, a tungsten carbide-cobalt-chrome (WC/Co/Cr) powder was processed by the DLMD method. WC/Co/Cr is a composite widely used as a wear-resistant material for cutting tools, molds, coatings and other severe applications. Because of its high hardness, poor ductility and low thermal expansion coefficient, depositing this material directly on the stainless steel substrate is very difficult. In order to overcome this problem, the strategy of functionally graded materials (FGM) was used. Colmonoy 227-F nickel alloy was chosen for this purpose in order to generate a mixture with the WC/Co/Cr powder. Four different materials were deposited, layer by layer, by mixing Colmonoy 227-F with an increasing amount of WC/Co/Cr powders, until obtaining a thick surface coating with a maximum amount of WC of 77.4 wt%. For each powder mixture, a mathematical model was applied to calculate optimal values of translation speed and overlap percentages. A metallographic examination was performed in order to detect macro- and micro-structures of the different materials. Finally, Vickers micro-hardness was measured at various locations along the transverse section to appreciate the gradual increase of the FGM hardness, starting from the substrate and culminating at the top surface of the last deposited material.

  4. Hyperfine interactions of short-lived {beta}-emitter {sup 8}Li in ferromagnetic Ni

    Energy Technology Data Exchange (ETDEWEB)

    Nojiri, Y.; Ishiga, K.; Onishi, T.; Sasaki, M.; Ohsumi, F.; Kawa, T.; Mihara, M.; Fukuda, M.; Matsuta, K.; Minamisono, T. [Osaka University, Department of Physics (Japan)

    1999-09-15

    Hyperfine interactions of {sup 8}Li impurity nucleus imbedded in ferromagnetic Ni metal were studied using the {beta}-NMR technique. Two kinds of hyperfine fields B{sub 82} were found, corresponding to two different final sites of Li atoms in the Ni lattice. The nuclear spin-lattice relaxation times T{sub 1} of {sup 8}Li in Ni were also determined for each field. Temperature dependencies of B{sub 82} and T{sub 1} were observed to deduce these values at T=0 K that can be compared with those calculated recently by Akai et al.

  5. Preparation of Metallic Iron Powder from Pyrite Cinder by Carbothermic Reduction and Magnetic Separation

    Directory of Open Access Journals (Sweden)

    Hongming Long

    2016-04-01

    Full Text Available The reduction and magnetic separation procedure of pyrite cinder in the presence of a borax additive was performed for the preparation of reduced powder. The effects of borax dosage, reduction temperature, reduction time and grinding fineness were investigated. The results show that when pyrite cinder briquettes with 5% borax were pre-oxidized at 1050 °C for 10 min, and reduced at 1050 °C for 80 min, with the grinding fineness (<0.44 mm passing 81%, the iron recovery was 91.71% and the iron grade of the magnetic concentrate was 92.98%. In addition, the microstructures of the products were analyzed by optical microscope, scanning electron microscope (SEM, and mineralography, and the products were also studied by the X-ray powder diffraction technique (XRD to investigate the mechanism; the results show that the borax additive was approved as a good additive to improve the separation of iron and gangue.

  6. Influence of Heavy Metal Powders on Rheological Properties of Poly(Lactic Acid)

    Science.gov (United States)

    Lebedev, S. M.; Gefle, O. S.; Amitov, E. T.; Berchuk, D. Yu.; Zhuravlev, D. V.

    2017-08-01

    Main properties of poly(lactic acid) (PLA) and composite materials on its basis filled with tungsten and lead powders are investigated. An anomalous decrease of the viscosity of melts of poly(lactic acid)/tungsten and poly(lactic acid)/lead composites is detected. The methods of differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and IR spectroscopy are used for investigation. It is shown that the temperature at which the composites filled with tungsten and lead begin to melt decreases by more than 8 and 3°C in comparison with neat PLA. Our investigations show impossibility of preparing radiation resistant polymer composites based on PLA filled with tungsten and lead powders.

  7. Metal-Matrix Hardmetal/Cermet Reinforced Composite Powders for Thermal Spray

    OpenAIRE

    Dmitri GOLJANDIN; Heikki SARJAS; Priit KULU; Helmo KÄERDI; Valdek MIKLI

    2012-01-01

    Recycling of materials is becoming increasingly important as industry response to public demands, that resources must be preserved and environment protected. To produce materials competitive in cost with primary product, secondary producers have to pursue new technologies and other innovations. For these purposes different recycling technologies for composite materials (oxidation, milling, remelting etc) are widely used. The current paper studies hardmetal/cermet powders produced by mechanica...

  8. Solid State Non-powder Process for Boron Nitride Nanotube Metal Matrix Composite, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Boron nitride nanotube (BNNT) reinforced metal matrix composites (MMCs) provide potential for advanced lightweight high stiffness structures that are critical for...

  9. Hyperfine splitting in lithium-like bismuth

    Energy Technology Data Exchange (ETDEWEB)

    Lochmann, Matthias; Froemmgen, Nadja; Hammen, Michael; Will, Elisa [Universitaet Mainz (Germany); Andelkovic, Zoran; Kuehl, Thomas; Litvinov, Yuri; Winters, Danyal; Sanchez, Rodolfo [GSI Helmholtzzentrum, Darmstadt (Germany); Botermann, Benjamin; Noertershaeuser, Wilfried [Technische Universitaet Darmstadt (Germany); Bussmann, Michael [Helmholtzzentrum Dresden-Rossendorf (Germany); Dax, Andreas [CERN, Genf (Switzerland); Hannen, Volker; Joehren, Raphael; Vollbrecht, Jonas; Weinheimer, Christian [Universitaet Muenster (Germany); Geppert, Christopher [Universitaet Mainz (Germany); GSI Helmholtzzentrum, Darmstadt (Germany); Stoehlker, Thomas [GSI Helmholtzzentrum, Darmstadt (Germany); Universitaet Heidelberg (Germany); Thompson, Richard [Imperial College, London (United Kingdom); Volotka, Andrey [Technische Universitaet Dresden (Germany); Wen, Weiqiang [IMP Lanzhou (China)

    2013-07-01

    High-precision measurements of the hyperfine splitting values on Li- and H-like bismuth ions, combined with precise atomic structure calculations allow us to test QED-effects in the regime of the strongest magnetic fields that are available in the laboratory. Performing laser spectroscopy at the experimental storage ring (ESR) at GSI Darmstadt, we have now succeeded in measuring the hyperfine splitting in Li-like bismuth. Probing this transition has not been easy because of its extremely low fluorescence rate. Details about this challenging experiment will be given and the achieved experimental accuracy are presented.

  10. The hyperfine field on 19Ne in Fe

    International Nuclear Information System (INIS)

    Ekwall, B.; Johansson, K.; Lidbjoerk, P.; Lindgren, B.; Bedi, S.

    1984-04-01

    The hyperfine field on 19 Ne in iron was measured with the TDPAD method. At 77 K the 19 Ne hyperfine field in iron was found to be -4.48(7) T. The temperature dependence of the hyperfine field in iron was studied between 77 K and 650 K. It was not possible to observe any hyperfine field on 19 Ne in nickel, using the same method. (author)

  11. Neutron powder diffraction of metal-organic frameworks for hydrogen storage

    International Nuclear Information System (INIS)

    Brown, Craig M.; Liu, Yun; Neumann, Dan A.

    2008-01-01

    We review recent structural studies that we have undertaken aimed at elucidating the fundamental properties of metal-organic framework materials and their interactions with hydrogen. We have shown that exposing coordinatively unsaturated metal centers can greatly enhance the hydrogen binding energy and that they result in a significant increase of the surface packing density of adsorbed hydrogen molecules on materials surface. We will review some of the structural aspects of these materials, especially the adsorbed hydrogen molecule surface packing density in one type of metal-organic framework, MOF-74, which can be packed even denser than that in solid hydrogen. (author)

  12. Infrared characterization of uranium oxide powders using a metal light pipe

    International Nuclear Information System (INIS)

    Cort, B.; Andrew, J.F.; Hansen, G.J.

    1987-01-01

    A light-pipe technique has been used to measure infrared spectra of UO 2 , U 3 O 8 , and UO 3 in the range 2000 to 450 cm -1 . Comparison with transmission spectra found in the literature indicates that the technique is very suitable for characterization of actinide powders and will therefore be a useful tool for future work, especially with hazardous materials such as actinides. The spectra obtained show all features predicted by group theory calculations, and the spectrum for the trioxide exhibits previously unseen features characteristic of uranyl bonds

  13. Effects of mold geometry on fiber orientation of powder injection molded metal matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Faiz, E-mail: faizahmad@petronas.com.my; Aslam, Muhammad, E-mail: klaira73@gmail.com; Altaf, Khurram, E-mail: khurram.altaf@petronas.com.my; Shirazi, Irfan, E-mail: irfanshirazi@hotmail.com [Mechanical Engineering Universiti Teknologi PETRONAS Malaysia (Malaysia)

    2015-07-22

    Fiber orientations in metal matrix composites have significant effect on improving tensile properties. Control of fiber orientations in metal injection molded metal composites is a difficult task. In this study, two mold cavities of dimensions 6x6x90 mm and 10x20x180 mm were used for comparison of fiber orientation in injection molded metal composites test parts. In both mold cavities, convergent and divergent flows were developed by modifying the sprue dimensions. Scanning electron microscope (SEM) was used to examine the fiber orientations within the test samples. The results showed highly aligned fiber in injection molded test bars developed from the convergent melt flow. Random orientation of fibers was noted in the composites test bars produced from divergent melt flow.

  14. Development of production technology by metallic powder injection molding for TiAl-type intermetallic compound with high efficiency

    International Nuclear Information System (INIS)

    Terauchi, S.; Teraoka, T.; Shinkuma, T.; Sugimoto, T.; Ahida, Y.

    2001-01-01

    Since a TiAl-type intermetallic compound has an excellent high temperature strength and corrosion resistance, in addition to light weight, it is expected to be applicable to the engine parts. However, it is difficult for TiAI to produce a part with a complex shape, and considerable cost will be required. In this study, it was tried to develop a technology for producing TiAl products with high density and high efficiency by using metal powder injection molding (MIM) process. Several kinds of TiAI alloy powders made by the self-propagating high temperature synthesis process were mixed with an organic binder, kneaded and then injection-molded into tensile specimens. These compacts were subjected to the treatment for removing the binder and sintering, resulted in a relative density as high as 97 %. By room and high temperature tensile tests, it was found that, Ti-47.4Al-2.6Cr (at%) has the strength and ductility as those of the conventional processed materials. (author)

  15. 3D Online Submicron Scale Observation of Mixed Metal Powder's Microstructure Evolution in High Temperature and Microwave Compound Fields

    Directory of Open Access Journals (Sweden)

    Dan Kang

    2014-01-01

    Full Text Available In order to study the influence on the mechanical properties caused by microstructure evolution of metal powder in extreme environment, 3D real-time observation of the microstructure evolution of Al-Ti mixed powder in high temperature and microwave compound fields was realized by using synchrotron radiation computerized topography (SR-CT technique; the spatial resolution was enhanced to 0.37 μm/pixel through the designed equipment and the introduction of excellent reconstruction method for the first time. The process of microstructure evolution during sintering was clearly distinguished from 2D and 3D reconstructed images. Typical sintering parameters such as sintering neck size, porosity, and particle size of the sample were presented for quantitative analysis of the influence on the mechanical properties and the sintering kinetics during microwave sintering. The neck size-time curve was obtained and the neck growth exponent was 7.3, which indicated that surface diffusion was the main diffusion mechanism; the reason was the eddy current loss induced by the external microwave fields providing an additional driving force for mass diffusion on the particle surface. From the reconstructed images and the curve of porosity and average particle size versus temperature, it was believed that the presence of liquid phase aluminum accelerated the densification and particle growth.

  16. The Structure and Properties of the Samples Produced by Selective Laser Melting of 410L Steel-based Metal Powder

    Science.gov (United States)

    Deev, Artem; Kuznetsov, Pavel; Zhukov, Anton; Bobyr, Vitaliy

    Additive technologies, which obtained the wide spreading in the last decade, allow producing items of any shape from metal materials practically without additional mechanical treatment. This approach based on the layer by layer melting of powder material accordingly to the premade 3D-CAD model, provides the geometrical accuracy which mostly depends on the size of the used material. In the present study, as material a 410 L steel powder was chosen, for which the basic dependencies between the selective laser melting (SLM) parameters and the mechanical properties were determined. Trial batches of standard samples for uniaxial tension and impact strength tests (according to the ASTM A370 and ASTM E8 M standards) were produced. It was shown that in the as build (after SLM) the fracture appeared to be brittle with the impact strength 3-5 J/cm2. The carried out heat treatment of quenching-tempering cycle and subsequent tests provide the viscous fracture and evaluation of impact strength up to 20-30 J/cm2. Presumably, this is due to a refinement of the grain structure and the inner stresses reduction of the samples, which also acknowledges the execution EBSD analysis, which points to the presence of quenched and tempered martensite. The presence of high inner stresses can be attributed to two α-γ-α transformations that were revealed by dilatometry investigation. In the range of cooling or heating rates from 1 to 500 °C/s temperatures of phase transformation are shifted.

  17. Modeling and multi-objective optimization of powder mixed electric discharge machining process of aluminum/alumina metal matrix composite

    Directory of Open Access Journals (Sweden)

    Gangadharudu Talla

    2015-09-01

    Full Text Available Low material removal rate (MRR and high surface roughness values hinder large-scale application of electro discharge machining (EDM in the fields like automobile, aerospace and medical industry. In recent years, however, EDM has gained more significance in these industries as the usage of difficult-to-machine materials including metal matrix composites (MMCs increased. In the present work, an attempt has been made to fabricate and machine aluminum/alumina MMC using EDM by adding aluminum powder in kerosene dielectric. Results showed an increase in MRR and decrease in surface roughness (Ra compared to those for conventional EDM. Semi empirical models for MRR and Ra based on machining parameters and important thermo physical properties were established using a hybrid approach of dimensional and regression analysis. A multi response optimization was also performed using principal component analysis-based grey technique (Grey-PCA to determine optimum settings of process parameters for maximum MRR and minimum Ra within the experimental range. The recommended setting of process parameters for the proposed process has been found to be powder concentration (Cp = 4 g/l, peak current (Ip = 3 A, pulse on time (Ton = 150 μs and duty cycle (Tau = 85%.

  18. Hyperfine interactions, the key to multiquark physics

    Energy Technology Data Exchange (ETDEWEB)

    Likpink, H.J.

    1988-08-08

    Clues in the search for a fundamental description of hadron physics based on QCD may be obtained from a phenomenological constituent quark model in which the color-electric force binds quarks into saturated color-singlet hadrons, and finer details of the spectrum and multiquark physics are dominated by the color-magnetic hyperfine interaction. 47 refs.

  19. Hyperfine interactions, the key to multiquark physics?

    International Nuclear Information System (INIS)

    Likpink, H.J.

    1988-01-01

    Clues in the search for a fundamental description of hadron physics based on QCD may be obtained from a phenomenological constituent quark model in which the color-electric force binds quarks into saturated color-singlet hadrons, and finer details of the spectrum and multiquark physics are dominated by the color-magnetic hyperfine interaction. 47 refs

  20. Design of conveyor utilization monitoring system: a case study of powder coating line in sheet metal fabrication

    Science.gov (United States)

    Prasetyo, Hoedi; Sugiarto, Yohanes; Nur Rosyidi, Cucuk

    2018-03-01

    Conveyor is a very useful equipment to replace manpower in transporting the goods. It highly influences the productivity, production capacity utilization and eventually the production cost. This paper proposes a system to monitor the utilization of conveyor at a low cost through a case study at powder coating process line in a sheet metal fabrication. Preliminary observation was conducted to identify the problems. The monitoring system was then built and executed. The system consists of two sub systems. First is sub system for collecting and transmitting the required data and the second is sub system for displaying the data. The system utilizes sensors, wireless data transfer and windows-based application. The test results showed that the whole system works properly. By this system, the productivity and status of the conveyor can be monitored in real time. This research enriches the development of conveyor monitoring system especially for implementation in small and medium enterprises.

  1. X-ray fluorescence spectrometric and optical emission spectographic analysis of thoria in thoriated copper metal powder

    International Nuclear Information System (INIS)

    Chandola, L.C.; Khanna, P.P.

    1984-01-01

    Two methods, one using the X-ray fluorescence (XRF) spectrometric technique and another using optical emission spectrographic (OES) technique are described for the determination of thoria in the concentration range 0.5-10% in thoriated copper metal powder. The precision of XRF method is superior to OES method but when sample quantity is very small, the OES method is useful. For XRF method, 500 mg sample is mixed with boric acid binding material and converted to a tablet for analysis. For OES method, only 200 mg sample is needed which is glued to the flat ends of two graphite electrodes for excitation by AC arc. The precision obtained in XRF is better than +-1% and in OES it is +-23%. (author)

  2. Sea-urchin-like ZnO nanostructures on Si by oxidation of Zn metal powders: Structural and optical properties

    Science.gov (United States)

    Umar, A.; Kim, S. H.; Hahn, Y. B.

    2006-01-01

    High-density sea-urchin-like ZnO nanostructures were grown on Si(100) substrates by the oxidation of metallic Zn powders at a low growth temperature without the use of any catalyst or additives. The morphological studies indicated that the grown structures are uniformly dispersed on the substrate and exhibited a sea-urchin-like shape consisting of several thousands of nanorods in one array, each ZnO nanorod of these structures having the diameter of 20-50 nm with the length of 2-4 μm. The high-resolution transmission electron microscopy and selected area electron diffraction patterns showed that the prepared sea-urchin-like ZnO nanostructures were single crystalline with wurtzite hexagonal structure and preferably grown along the [0001] direction. Room temperature Raman scattering and photoluminescence studies found that the as-grown nanostructures have good crystal quality with the hexagonal wurtzite phase.

  3. Improvement of Surface Properties of Inconel718 by HVOF Coating with WC-Metal Powder and by Laser Heat Treatment of the Coating

    OpenAIRE

    Chun, Hui Gon; Cho, Tong Yul; Yoon, Jae Hong; Lee, Gun Hwan

    2015-01-01

    High-velocity oxygen-fuel (HVOF) thermal spray coating with WC-metal powder was carried out by using optimal coating process on an Inconel718 surface for improvement of the surface properties, friction, wear, and corrosion resistance. Binder metals such as Cr and Ni were completely melted and WC was decomposed partially to W2C and graphite during the high temperature (up to 3500°C) thermal spraying. The melted metals were bonded with WC and other carbides and were formed as WC-metal coating. ...

  4. Metals for bone implants. Part 1. Powder metallurgy and implant rendering.

    Science.gov (United States)

    Andani, Mohsen Taheri; Shayesteh Moghaddam, Narges; Haberland, Christoph; Dean, David; Miller, Michael J; Elahinia, Mohammad

    2014-10-01

    New metal alloys and metal fabrication strategies are likely to benefit future skeletal implant strategies. These metals and fabrication strategies were looked at from the point of view of standard-of-care implants for the mandible. These implants are used as part of the treatment for segmental resection due to oropharyngeal cancer, injury or correction of deformity due to pathology or congenital defect. The focus of this two-part review is the issues associated with the failure of existing mandibular implants that are due to mismatched material properties. Potential directions for future research are also studied. To mitigate these issues, the use of low-stiffness metallic alloys has been highlighted. To this end, the development, processing and biocompatibility of superelastic NiTi as well as resorbable magnesium-based alloys are discussed. Additionally, engineered porosity is reviewed as it can be an effective way of matching the stiffness of an implant with the surrounding tissue. These porosities and the overall geometry of the implant can be optimized for strain transduction and with a tailored stiffness profile. Rendering patient-specific, site-specific, morphology-specific and function-specific implants can now be achieved using these and other metals with bone-like material properties by additive manufacturing. The biocompatibility of implants prepared from superelastic and resorbable alloys is also reviewed. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  5. Systems and Methods for Designing and Fabricating Contact-Free Support Structures for Overhang Geometries of Parts in Powder-Bed Metal Additive Manufacturing

    Science.gov (United States)

    Chou, Yuag-Shan (Inventor); Cooper, Kenneth (Inventor)

    2017-01-01

    Systems and methods are provided for designing and fabricating contact-free support structures for overhang geometries of parts fabricated using electron beam additive manufacturing. One or more layers of un-melted metallic powder are disposed in an elongate gap between an upper horizontal surface of the support structure and a lower surface of the overhang geometry. The powder conducts heat from the overhang geometry to the support structure. The support structure acts as a heat sink to enhance heat transfer and reduce the temperature and severe thermal gradients due to poor thermal conductivity of metallic powders underneath the overhang. Because the support structure is not connected to the part, the support structure can be removed freely without any post-processing step.

  6. Optical Characteristics of Polystyrene Based Solid Polymer Composites: Effect of Metallic Copper Powder

    Directory of Open Access Journals (Sweden)

    Shujahadeen B. Aziz

    2013-01-01

    Full Text Available Solid polymer composites (SPCs were prepared by solution cast technique. The optical properties of polystyrene doped with copper powder were performed by means of UV-Vis technique. The optical constants were calculated by using UV-Vis spectroscopy. The dispersion regions were observed in both absorption and refractive index spectra at lower wavelength. However, a plateau can be observed at high wavelengths. The small extinction coefficient compared to the refractive index reveals the transparency of the composite samples. The refractive index and optical band gap were determined from the reflectance and optical absorption coefficient data, respectively. The nature of electronic transition from valence band to conduction band was determined and the energy band gaps of the solid composite samples were estimated. It was observed that, upon the addition of Cu concentration, the refractive index increased while the energy gaps are decreased. The calculated refractive indexes (low index of refraction of the samples reveal their availability in waveguide technology.

  7. Development of solid-state joining technology of dissimilar metals using amorphous metastable alloy powders

    International Nuclear Information System (INIS)

    Lee, Min Ku; Rhee, Chang Kyu; Uhm, Young Rang; Park, Jin Ju; Lee, Jeong Gu; Kim, Gwang Ho; Hong, Sung Mo; Lee, Jong Geuk; Kim, Kyoung Ho

    2007-04-01

    Many nuclear components such as nozzles, steam generator, pipes, condensers, and heat exchangers require a realization of the reliable and high-performance joining or welding between the dissimilar metals or alloys, despite the fact that their melting points, thermal expansion coefficients and physical properties are quite different from each other. The conventional arc welding processes (SMAW, TIG), however, which is currently used as a welding process for NPP components, have not met the requirements of obtaining a reliable and high-quality dissimilar joints, as demonstrated from a number of the previously reported accidents or material failures in the welded joints. This originates from the various weaknesses of the arc welding processes (more than 1700 .deg. C) such as high residual stresses which is sensitive to SCC, porous or deformed joint structures, a formation of grain-coarsened HAZ and an induced degradation of the base metals in the vicinity of the joint. Moreover, they are not applicable to a joining of the dissimilar metals when their melting point or mechanical/physical properties are quite different. In this research, the low-temperature joining (700 .deg. C - 800 .deg. C) and simultaneously strong diffusion bonding technologies between the dissimilar Ti and Cu metals have been developed for the applications to the dissimilar joints of various nuclear tube components

  8. Procedure for the conversion of a metal oxide powder to a fine grained ceramic material

    International Nuclear Information System (INIS)

    Ferrell, L.J.

    1978-01-01

    A procedure for sintering metal oxides is described which gives a product with significantly smaller grain size and better grain size distribution than previous processes. The procedure is presented as applied to aluminium oxide, but it is also stated to be applicable to uranium dioxide. A pellet density of within 1/2 percent of the theoretical maximum can be obtained. No grinding or surface treatment of the pellets is necessary. (JIW)

  9. Experimental investigations of adsorption characteristics and porosity of activated metal hydride powders

    Science.gov (United States)

    Kazakov, A. N.; Romanov, I. A.; Kuleshov, V. N.; Dunikov, D. O.

    2017-11-01

    In the present work non-uniformities of microstructure, porosity and adsorption characteristics of La0.9Ce0.1Ni5 metal hydride by the height of the bed are investigated. A 500 g metal hydride bed was cycled inside a vertical metal hydride reactor and three samples was taken from top, middle and bottom of the bed. Non-uniform particle distributions and bed densification were observed, the bed porosity is around 0.58-0.67 at the top and middle parts of the bed and 0.46-0.54 at the bottom, where a dense and robust agglomerate was formed during the cycling. Specific surface area measured by nitrogen adsorption methods is 1.8-2.1 m2/g at the top of the bed, 4.2-5.4 m2/g in the middle and 1.1-1.5 m2/g at the bottom. The maximum is connected with higher degree of particle dispersion without effects from particle agglomeration.

  10. Powder Diffraction

    Science.gov (United States)

    Hart, Michael

    The importance of x-ray powder diffraction as an analytical tool for phase identification of materials was first pointed out by Debye and Scherrer1,2 in Germany and, quite independently, by Hull3,4 in the United States of America. Three distinct periods of evolution lead to ubiquitous application in many fields of science and technology. In the, first period, until the- mid-1940's. applications were and developed covering broad categories of materials including inorganic materials, minerals, cerarffics, metals, alloys, organic materials and polymers. During this formative period, the concept of quantitative phase analysis was demonstrated5. In the second period there followed the blossoming of technology and commercial instruments became widely used. The history is well summarized by Parrish6 and by Langford and Loudr7. By 1980 there were probably 10000 powder diffractometers in routine use, making it the most widely used of all x-ray crystallographic instruments. In the third, present, period data bases became firmly established and sophisticated pattern fitting and recognition software made many aspects of powder diffraction analysis routine. High resolution, tunable powder diffractometers were developed at sources of synchrotron radiation8-10. The tunability of the spectrum made it possible to exploit all the subtleties of x-ray spectroscopy in diffraction experiments11.

  11. Powder diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Hart, M.

    1995-12-31

    the importance of x-ray powder diffraction as an analytical tool for phase identification of materials was first pointed out by Debye and Scherrer in Germany and, quite independently, by Hull in the US. Three distinct periods of evolution lead to ubiquitous application in many fields of science and technology. In the first period, until the mid-1940`s, applications were and developed covering broad categories of materials including inorganic materials, minerals, ceramics, metals, alloys, organic materials and polymers. During this formative period, the concept of quantitative phase analysis was demonstrated. In the second period there followed the blossoming of technology and commercial instruments became widely used. The history is well summarized by Parrish and by Langford and Loueer. By 1980 there were probably 10,000 powder diffractometers in routine use, making it the most widely used of all x-ray crystallographic instruments. In the third, present, period data bases became firmly established and sophisticated pattern fitting and recognition software made many aspects of powder diffraction analysis routine. High resolution, tunable powder diffractometers were developed at sources of synchrotron radiation. The tunability of the spectrum made it possible to exploit all the subtleties of x-ray spectroscopy in diffraction experiments.

  12. Powder diffraction

    International Nuclear Information System (INIS)

    Hart, M.

    1995-01-01

    The importance of x-ray powder diffraction as an analytical tool for phase identification of materials was first pointed out by Debye and Scherrer in Germany and, quite independently, by Hull in the US. Three distinct periods of evolution lead to ubiquitous application in many fields of science and technology. In the first period, until the mid-1940's, applications were and developed covering broad categories of materials including inorganic materials, minerals, ceramics, metals, alloys, organic materials and polymers. During this formative period, the concept of quantitative phase analysis was demonstrated. In the second period there followed the blossoming of technology and commercial instruments became widely used. The history is well summarized by Parrish and by Langford and Loueer. By 1980 there were probably 10,000 powder diffractometers in routine use, making it the most widely used of all x-ray crystallographic instruments. In the third, present, period data bases became firmly established and sophisticated pattern fitting and recognition software made many aspects of powder diffraction analysis routine. High resolution, tunable powder diffractometers were developed at sources of synchrotron radiation. The tunability of the spectrum made it possible to exploit all the subtleties of x-ray spectroscopy in diffraction experiments

  13. Hyperfine interactions in magnetoelectric hexaferrite system

    Energy Technology Data Exchange (ETDEWEB)

    Kouril, Karel; Chlan, Vojtech; Stepankova, Helena [Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, 180 00 Prague 8 (Czech Republic); Novak, Pavel, E-mail: novakp@fzu.c [Institute of Physics ASCR, Cukrovarnicka 10, 162 53 Prague 6 (Czech Republic); Knizek, Karel; Hybler, Jiri [Institute of Physics ASCR, Cukrovarnicka 10, 162 53 Prague 6 (Czech Republic); Kimura, Tsuyoshi; Hiraoka, Yuji [Graduae School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Bursik, Josef [Institute of Inorganic Chemistry ASCR, 250 68 Rez (Czech Republic)

    2010-05-15

    Nuclear magnetic resonance (NMR) in Y-hexaferrite system (Ba{sub 1-x}Sr{sub x}){sub 2}Zn{sub 2}Fe{sub 12}O{sub 22} was measured on both monocrystalline and polycrystalline samples at liquid helium temperature. Corresponding ab-initio calculation of the hyperfine parameters was also performed. The signal from {sup 57}Fe was detected in the frequency interval 65-76 MHz, while NMR spectrum of {sup 67}Zn nuclei occurs between 15 and 30 MHz. Due to the disorder in two tetrahedral sublattices occupied partly by Zn and partly by Fe, the NMR lines are broad and the spectra are poorly resolved. Comparison between the experimentally observed {sup 67}Zn spectra and the spectra modelled using the calculated hyperfine parameters was made. It indicates that the spectra of {sup 67}Zn can be used to determine the distribution of Zn and Fe between the two tetrahedral sublattices.

  14. Hyperfine interactions measured by nuclear orientation technique

    International Nuclear Information System (INIS)

    Brenier, R.

    1982-01-01

    This report concerns the use of hyperfine interaction to magnetism measurements and to the determination of the nuclear structure of Terbium isotopes by the low temperature nuclear orientation technique. In the first part we show that the rhodium atom does not support any localized moment in the chromium matrix. The hyperfine magnetic field at the rhodium nuclear site follows the Overhauser distribution, and the external applied magnetic field supports a negative Knight shift of 16%. In the second part we consider the structure of neutron deficient Terbium isotopes. We introduce a coherent way of evaluation and elaborate a new nuclear thermometer. The magnetic moments allows to strike on the studied states configuration. The analysis of our results shows a decrease of the nuclear deformation for the lighter isotopes [fr

  15. Hyperfine structure of muonic lithium ions

    Directory of Open Access Journals (Sweden)

    Alexey P. Martynenko

    2015-06-01

    Full Text Available On the basis of perturbation theory in fine structure constant $\\alpha$ and the ratio of electron to muon masses we calculate recoil corrections of order $\\alpha^4 (M_e/M_\\mu$, $\\alpha^4 (M_e/M_\\mu^2\\ln(M_e/M_\\mu$, $\\alpha^4 (M_e/M_\\mu^2$, $\\alpha^5(m_e/m_\\mu\\ln(m_e/m_\\mu$ to hyperfine splitting of the ground state in muonic lithium ions $(\\mu e ^6_3\\mathrm{Li}^+$ and $(\\mu e ^7_3\\mathrm{Li}^+$. We obtain total results for the ground state small hyperfine splittings in $(\\mu e ^6_3\\mathrm{Li}^+$ $\\Delta\

  16. The hyperfine Paschen–Back Faraday effect

    International Nuclear Information System (INIS)

    Zentile, Mark A; Andrews, Rebecca; Weller, Lee; Adams, Charles S; Hughes, Ifan G; Knappe, Svenja

    2014-01-01

    We investigate experimentally and theoretically the Faraday effect in an atomic medium in the hyperfine Paschen–Back regime, where the Zeeman interaction is larger than the hyperfine splitting. We use a small permanent magnet and a micro-fabricated vapour cell, giving magnetic fields of the order of a tesla. We show that for low absorption and small rotation angles, the refractive index is well approximated by the Faraday rotation signal, giving a simple way to measure the atomic refractive index. Fitting to the atomic spectra, we achieve magnetic field sensitivity at the 10 −4 level. Finally we note that the Faraday signal shows zero crossings which can be used as temperature insensitive error signals for laser frequency stabilization at large detuning. The theoretical sensitivity for 87 Rb is found to be ∼40 kHz °C −1 . (paper)

  17. Hyperfine Interactions in Ferrites with Spinel Structure

    OpenAIRE

    Chlan, Vojtěch

    2013-01-01

    Title: Hyperfine Interactions in Ferrites with Spinel Structure Author: Vojtěch Chlan Faculty of Mathematics and Physics, Charles University in Prague Supervisor: Prof. RNDr. Helena Štěpánková, CSc. Abstract: Ferrite systems with spinel structure, manganese ferrite, lithium ferrite and magnetite, are studied experimentally by nuclear magnetic resonance (NMR) spectroscopy and from the first principles by electron structure calculations based on density functional theory (DFT). Manganese ferrit...

  18. Magnetic hyperfine field at a Cd impurity diluted in RCo{sub 2} at finite temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, A.L. de, E-mail: alexandre.oliveira@ifrj.edu.br [Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro, Campus Nilópolis – RJ (Brazil); Chaves, C.M., E-mail: cmch@cbpf.br [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro (Brazil); Oliveira, N.A. de [Instituto de Física Armando Dias Tavares, Universidade do Estado do Rio de Janeiro, Rio de Janeiro (Brazil); Troper, A. [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro (Brazil)

    2015-06-15

    The local magnetic moments and the magnetic hyperfine fields at an s–p Cd impurity diluted in inter-metallic Laves phase compounds RCo{sub 2} (R=Gd, Tb) at finite temperatures are calculated. For other rare earth elements (light or heavy) the pure compounds display a magnetic first order transition and are not describable by our formalism. The host has two coupled lattices (R and Co) both having itinerant d electrons but only the rare earth lattice has localized f electrons. They all contribute to the magnetization of the host and also to the local moment and to the magnetic hyperfine field at the impurity. The investigation of magnetic hyperfine field in these materials then provides valuable information on the d-itinerant electrons and also on the localized (4f) magnetic moments. For the d–d electronic interaction we use the Hubbard–Stratonovich identity thus allowing the employment of functional integral in the static saddle point approximation. Our model reproduces quite well the experimental data. - Highlights: • A functional integral method in the static limit, producing site disorder, is used. • The site disorder is treated with the coherent potential approximation (CPA) • A Friedel sum rule gives a self-consistency condition for the impurity energy. • The experimental curve of hyperfine fields×temperature is very well reproduced.

  19. Structure and hardness of a hard metal alloy prepared with a WC powder synthesized at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Costa, F.A. da [Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais, UFRN, Campus Universitario, 59072-970 Natal, RN (Brazil)], E-mail: francineac@yahoo.com; Medeiros, F.F.P. de [Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais, UFRN, Campus Universitario, 59072-970 Natal, RN (Brazil); Silva, A.G.P. da [Laboratorio de Materiais Avancados, UENF, 28015-620 Campos de Goytacazes, RJ (Brazil); Gomes, U.U. [Departamento de Fisica Teorica e Experimental, UFRN, Campus Universitario, 59072-970 Natal, RN (Brazil); Filgueira, M. [Laboratorio de Materiais Avancados, UENF, 28015-620 Campos de Goytacazes, RJ (Brazil); Souza, C.P. de [Laboratorio de Termodinamica e Reatores, UFRN, Campus Universitario, 59072-970 Natal, RN (Brazil)

    2008-06-25

    The structure and hardness of a WC-10 wt% Co alloy prepared with an experimental WC powder are compared with those of another alloy of the same composition produced under the same conditions and prepared with a commercial WC powder. The experimental WC powder was synthesized by a gas-solid reaction between APT and methane at low temperature and the commercial WC powder was conventionally produced by a solid-solid reaction between tungsten and carbon black. WC-10 wt% Co alloys with the two powders were prepared under the same conditions of milling and sintering. The structure of the sample prepared with the experimental WC powder is homogeneous and coarse grained. The structure of the sample prepared with the commercial powder is heterogeneous. Furthermore the size and shape of the WC grains are significantly different.

  20. Cu-TiB metal matrix composites prepared by powder metallurgy route

    Directory of Open Access Journals (Sweden)

    Guo Z.

    2015-01-01

    Full Text Available Titanium boride (TiB is characterized by good conductivity, high strength and high melting point. In this work, TiB was used to make Cu-TiB metal matrix composites (MMCs. Amounts of TiB added into Cu matrix were 2wt.%, 5wt.%, 10 wt.% and 15 wt.%. The samples were pressed at pressures of 500MPa, 600MPa, 700MPa and 800MPa and sintered at 820o and 920o, respectively. The properties of the sintered composites such as hardness and impact toughness were studied. Hardness and impact toughness of samples increased with increasing pressures and decreased with increasing contents of TiB. Composite with good mechanical properties and high conductivity was obtained from the sample containing 2wt.%TiB compacted at 800MPa and sintered at 920o. It was shown that 2wt.% TiB is a suitable content to make Cu-TiB MMCs with good mechanical properties and excellent conductivity.

  1. Structural behavior and microstructural hard metal sintered at 1350 deg C from the powder of nanometer WC with 10 wt% Co

    Energy Technology Data Exchange (ETDEWEB)

    Batista, A.C.; Perpetuo, G.J.; Leocadio, R.R.V., E-mail: adrianocorrea77@gmail.com [Rede Tematica de Engenharia de Materiais (REDEMAT), Ouro Preto, Minas Gerais (Brazil); Oliveira, H.C.P. de [Instituto Superior Tecnico (IST), Lisboa (Portugal). Departamento de Materiais

    2014-07-01

    The hard metal (WC-10%Co), processed via powder metallurgy, using powder of nanometer WC, were characterized from the point of view to the microstructural and structural techniques, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDS) for mapping and punctual. To analyze the behavior of hard metal after the sintering process performed in resistive furnace at 1350°C for 1 hour under vacuum of 10-2 mbar, the analysis identified the formation of WC grains, the pore distribution and behavior and evolution of the phases WC and Co, generating phases η (Co{sub 3}W{sub 3}C and Co{sub 6}W{sub 6}C). (author)

  2. Development of Metal/Polymer Mixtures Dedicated to Macro and Micro powder Injection Moulding : Experiments and Simulations

    International Nuclear Information System (INIS)

    Quinard, C.; Barriere, T.; Gelin, J. C.; Song, J. P.; Cheng, Z. Q.; Liu, B. S.

    2007-01-01

    Important research tasks at ENSMM/LMA are concerned for the development of mixtures of fine powders associated to polymer binders dedicated to the powder injection moulding (PIM) and to the powder injection micro-moulding (μPIM) in accordance with many works already carried out with different feedstock suppliers dedicated to the macro-components. These research tasks are completed with the simulations of injection and sintering for solid state diffusion for to validate the mumerical models

  3. Observation of the hyperfine spectrum of antihydrogen.

    Science.gov (United States)

    Ahmadi, M; Alves, B X R; Baker, C J; Bertsche, W; Butler, E; Capra, A; Carruth, C; Cesar, C L; Charlton, M; Cohen, S; Collister, R; Eriksson, S; Evans, A; Evetts, N; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Gutierrez, A; Hangst, J S; Hardy, W N; Hayden, M E; Isaac, C A; Ishida, A; Johnson, M A; Jones, S A; Jonsell, S; Kurchaninov, L; Madsen, N; Mathers, M; Maxwell, D; McKenna, J T K; Menary, S; Michan, J M; Momose, T; Munich, J J; Nolan, P; Olchanski, K; Olin, A; Pusa, P; Rasmussen, C Ø; Robicheaux, F; Sacramento, R L; Sameed, M; Sarid, E; Silveira, D M; Stracka, S; Stutter, G; So, C; Tharp, T D; Thompson, J E; Thompson, R I; van der Werf, D P; Wurtele, J S

    2017-08-02

    The observation of hyperfine structure in atomic hydrogen by Rabi and co-workers and the measurement of the zero-field ground-state splitting at the level of seven parts in 10 13 are important achievements of mid-twentieth-century physics. The work that led to these achievements also provided the first evidence for the anomalous magnetic moment of the electron, inspired Schwinger's relativistic theory of quantum electrodynamics and gave rise to the hydrogen maser, which is a critical component of modern navigation, geo-positioning and very-long-baseline interferometry systems. Research at the Antiproton Decelerator at CERN by the ALPHA collaboration extends these enquiries into the antimatter sector. Recently, tools have been developed that enable studies of the hyperfine structure of antihydrogen-the antimatter counterpart of hydrogen. The goal of such studies is to search for any differences that might exist between this archetypal pair of atoms, and thereby to test the fundamental principles on which quantum field theory is constructed. Magnetic trapping of antihydrogen atoms provides a means of studying them by combining electromagnetic interaction with detection techniques that are unique to antimatter. Here we report the results of a microwave spectroscopy experiment in which we probe the response of antihydrogen over a controlled range of frequencies. The data reveal clear and distinct signatures of two allowed transitions, from which we obtain a direct, magnetic-field-independent measurement of the hyperfine splitting. From a set of trials involving 194 detected atoms, we determine a splitting of 1,420.4 ± 0.5 megahertz, consistent with expectations for atomic hydrogen at the level of four parts in 10 4 . This observation of the detailed behaviour of a quantum transition in an atom of antihydrogen exemplifies tests of fundamental symmetries such as charge-parity-time in antimatter, and the techniques developed here will enable more-precise such tests.

  4. Magnetic hyperfine field at caesium in iron

    International Nuclear Information System (INIS)

    Ashworth, C.J.; Back, P.; Stone, N.J.; White, J.P.; Ohya, S.

    1990-01-01

    We report temperature dependence of nuclear orientation (NO), and the first observation of NMR/ON on Cs in iron. 132,136 Cs were implanted at room temperature into polycrystalline and single crystal iron. NO values for the (average) magnetic hyperfine field B hf (CsFe) are close to 34 T, intermediate between the value of 40.7 T found in on-line samples made at mK temperatures and the NMR/ON value of 27.8(2) T. The latter studies. The site/field distribution is briefly discussed. (orig.)

  5. Hyperfine structure studies with the COMPLIS facility

    CERN Document Server

    Crawford, J E; Le Blanc, F; Lunney, M D; Obert, J; Oms, J; Putaux, J C; Roussière, B; Sauvage, J; Zemlyanoi, S G; Verney, D; Pinard, J; Cabaret, L A; Duong, H T; Huber, G; Krieg, M; Sebastian, V; Girod, M; Peru, S; Genevey, J; Ibrahim, F; Lettry, Jacques

    1998-01-01

    COMPLIS is an experimental facility designed to carry out spectroscopic studies on radioisotopes produced by disintegration of elements available at CERN's Booster-ISOLDE on-line isotope separator. During recent series of experimental runs, hyperfine structure measurements have yielded information on nuclear moments and deformations of platinum and iridium isotopes, For the first time, population by alpha -decay from Hg was exploited to investigate /sup 178/-/sup 181/Pt-the most neutron-deficient Pt isotopes yet studied. Successful measurements have recently been carried out on /sup 182-189/Ir. (10 refs).

  6. Measurements of hyperfine constants in Ca+

    International Nuclear Information System (INIS)

    Goble, A.T.; Maleki, S.

    1990-01-01

    We have measured the hyperfine constants A( 2 S 1/2 ), A( 2 P 1/2 ), and A( 2 P 3/2 ) for Ca + . We compare our results with the calculations of Martensson-Pendrill and Salomonson [Phys. Rev. A 30, 712 (1984)], who used many-body perturbation theory (MBPT). The agreement between our results and MBPT calculations for Ca + is about 3%, which is comparable to similar comparisons reported for Cs [S. Blundell, in 2 Relativistic, Quantum Electrodynamic, and Weak Interaction Effects in Atoms, AIP Conf. Proc. No. 189, edited by Walter Johnson, Peter Mohr, and Joseph Sucher (AIP, New York, 1988)

  7. Nagaoka's atomic model and hyperfine interactions.

    Science.gov (United States)

    Inamura, Takashi T

    2016-01-01

    The prevailing view of Nagaoka's "Saturnian" atom is so misleading that today many people have an erroneous picture of Nagaoka's vision. They believe it to be a system involving a 'giant core' with electrons circulating just outside. Actually, though, in view of the Coulomb potential related to the atomic nucleus, Nagaoka's model is exactly the same as Rutherford's. This is true of the Bohr atom, too. To give proper credit, Nagaoka should be remembered together with Rutherford and Bohr in the history of the atomic model. It is also pointed out that Nagaoka was a pioneer of understanding hyperfine interactions in order to study nuclear structure.

  8. Role of HSAB concept in understanding biosorptive behaviour of various metal ions employing green biosorbent - Dry Cow Dung Powder

    Science.gov (United States)

    Bagla, Hemlata; Khilnani, Roshan

    2016-04-01

    Hard & Soft Acid Base concept, HSAB theory given by Pearson, elucidates the crucial role of HSAB characteristics of both pollutants as well as the aqueous milieu. This theory can also explain the biosorptive behaviour of Dry Cow dung Powder, which helps in governing the success of process. The various metal ionic species exhibit a preference for the ligand binding on the biomass based on its chemical coordination characteristics. A comparative batch equilibration biosorptive assay has been carried out employing radiotracer technique for uptake of Cr(III), Cr(VI), Cd(II), Hg(II), Sr(II), Cs(I) and Co(II) at optimum biosorption parameters. To study the effect of interference of different salts on the percentage biosorption of metal ions on DCP, different organic as well as inorganic salts with varying proportion of 10 mg, 25 mg, 50 mg and 100 mg have been studied. The dynamics of the biosorption in terms of the order of the rate constant was studied applying different kinetic models. The best fitting model was Lagergren pseudo second order model. DCP, an eco-friendly humiresin, enriched with minerals, carbohydrates, fats, proteins, bile pigments, aliphatic - aromatic species such as 'Humic acid', Fulvic acid and many naturally present functional group such as carboxyl, phenols, quinols, amide etc. of both hard and soft nature, making it 'combo' in nature sorbs both concerned metal ions as well as ligands present in the system. Thus the ligands which were masking the biosorption process of heavy metal ions in this study were treated by mere increase in the dose of DCP, which successfully solves the problem without affecting efficiency of the process. This is exemplified by three very basic interactions happening in multicomponent system i.e. Synergism: Mutual enhancement; Antagonism: Mutual decrement; Non-interaction: Neutral effect. Thus DCP has a great potential in the field of water decontamination, industrial water treatment and in abatement of water pollution. So

  9. EXPLOITATIVE DESTRUCTION FEATURES FOR DETONATION ULTRADISPERSED DIAMONDS OF INITIAL METALLIC PROTECTION FOR ABRASIVE POWDER GRAINS TO DIAMOND-SPARK GRINDING TOOLS

    Directory of Open Access Journals (Sweden)

    Yury GUTSALENKO

    2015-05-01

    Full Text Available The problem of exploitation of diamond grinding wheels with metal coating for their grains including detonation ultra-dispersed diamonds to increase functional reliability to maintain the initial integrity of grains in the pressing and sintering of diamond-metal composites in the tool production is considered. One problem is that the presence of detonation ultra-dispersed diamonds in the grain metal coating of diamond powders not only improves the coating functional reliability in protection from destruction in the subsequent pressing and sintering in the production tool, but also resistance of such coating to the opening of the diamond cutting basis of the grains on the grinding wheel working surface that come into working contact with the material being processed. An analysis of the features of an effective exploitative destruction of detonation ultra-dispersed diamonds in the metal coating using electric current in the tool of the diamondspark grinding processes is presented.

  10. Powder technology

    International Nuclear Information System (INIS)

    Agueda, Horacio

    1989-01-01

    Powder technology is experiencing nowadays a great development and has broad application in different fields: nuclear energy, medicine, new energy sources, industrial and home artifacts, etc. Ceramic materials are of daily use as tableware and also in the building industry (bricks, tiles, etc.). However, in machine construction its utilization is not so common. The same happens with metals: powder metallurgy is employed less than traditional metal forming techniques. Both cases deal with powder technology and the forming techniques as far as the final consolidation through sintering processes are very similar. There are many different methods and techniques in the forming stage: cold-pressing, slip casting, injection molding, extrusion molding, isostatic pressing, hot-pressing (which involves also the final consolidation step), etc. This variety allows to obtain almost any desired form no matter how complex it could be. Some applications are very specific as in the case of UO 2 pellets (used as nuclear fuels) but with the same technique and other materials, it is possible to manufacture a great number of different products. This work shows the characteristics and behaviour of two magnetic ceramic materials (ferrites) fabricated in the laboratory of the Applied Research Division of the Bariloche Atomic Center for different purposes. Other materials and products made with the same method are also mentioned. Likewise, densities and shrinkage obtained by different methods of forming (cold-pressing, injection molding, slip casting and extrusion molding) using high-purity alumina (99.5% Al 2 O 3 ). Finally, different applications of such methods are given. (Author) [es

  11. Hyperfine structure of hydrogenlike thallium isotopes

    International Nuclear Information System (INIS)

    Beiersdorfer, Peter; Utter, Steven B.; Wong, Keith L.; Crespo Lopez-Urrutia, Jose R.; Britten, Jerry A.; Chen, Hui; Harris, Clifford L.; Thoe, Robert S.; Thorn, Daniel B.; Traebert, Elmar

    2001-01-01

    The hyperfine splitting of the 1s ground state of hydrogenlike Tl has been measured for the two stable isotopes using emission spectroscopy in the SuperEBIT electron-beam ion trap, giving 3858.22±0.30 {angstrom} for 203 Tl 80+ and 3821.84±0.34 {angstrom} for 205 Tl 80+ with a wavelength difference Δλ=36.38±0.35 {angstrom}. This difference is consistent with estimates based on hyperfine anomaly data for neutral Tl only if finite size effects are included in the calculation. By using previously determined nuclear magnetic moments, and applying appropriate corrections for the nuclear charge distribution and radiative effects, the experimental splittings can be interpreted in terms of nuclear magnetization radii m 2 > 1/2 =5.83(14) fm for 203 Tl and m 2 > 1/2 =5.89(14) fm for 205 Tl. These values are 10% larger than derived from single-particle nuclear magnetization models, and are slightly larger than the corresponding charge distributions

  12. Hyperfine structure of hydrogenlike thallium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Beiersdorfer, Peter; Utter, Steven B.; Wong, Keith L.; Crespo Lopez-Urrutia, Jose R.; Britten, Jerry A.; Chen, Hui; Harris, Clifford L.; Thoe, Robert S.; Thorn, Daniel B.; Traebert, Elmar (and others)

    2001-09-01

    The hyperfine splitting of the 1s ground state of hydrogenlike Tl has been measured for the two stable isotopes using emission spectroscopy in the SuperEBIT electron-beam ion trap, giving 3858.22{+-}0.30 {angstrom} for {sup 203}Tl{sup 80+} and 3821.84{+-}0.34 {angstrom} for {sup 205}Tl{sup 80+} with a wavelength difference {Delta}{lambda}=36.38{+-}0.35 {angstrom}. This difference is consistent with estimates based on hyperfine anomaly data for neutral Tl only if finite size effects are included in the calculation. By using previously determined nuclear magnetic moments, and applying appropriate corrections for the nuclear charge distribution and radiative effects, the experimental splittings can be interpreted in terms of nuclear magnetization radii {sup 1/2}=5.83(14) fm for {sup 203}Tl and {sup 1/2}=5.89(14) fm for {sup 205}Tl. These values are 10% larger than derived from single-particle nuclear magnetization models, and are slightly larger than the corresponding charge distributions.

  13. Study of hyperfine parameters in Co-doped tin dioxide using PAC spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Juliana M.; Carbonari, Artur W.; Martucci, Thiago; Costa, Messias S.; Saxena, Rajendra N. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Vianden, R.; Kessler, P.; Geruschke, T.; Steffens, M., E-mail: vianden@hiskp.uni-bonn.d [Rheinische Friedrich-Wilhelms-Universitaet Bonn (HISKP- Bonn) (Germany). Helmholtz - Institut fuer Strahlen- und Kernphysik

    2011-07-01

    PAC technique has been used to measure the hyperfine interactions in nano-structured powder samples of semiconducting SnO{sub 2} doped with Co. The aim of this work is to compare the results of PAC measurements using two different techniques of introducing the radioactive {sup 111}In probe nuclei in the sample of SnO{sub 2} doped with Co. The perturbed gamma-gamma angular correlation (PAC) spectroscopy is used for the measurements of the magnetic hyperfine field (MHF) and the electric field gradient (EFG) at {sup 111}Cd sites in SnO{sub 2} doped with 1% and 2% Co. The measurement of EFG is used to study the defects introduced in the semiconductor material and also for the identification of different phases formed within the compound. The techniques utilized for introducing the radioactive {sup 111}In in the sample are the ion-implantation using radioactive ion beam of {sup 111}In and the chemical process in which {sup 111}InCl{sub 3} solution is added during the preparation of SnO{sub 2} doped with Co using sol gel method. The ion-implantation of {sup 111}In in SnO{sub 2} doped with Co was carried out using the University of Bonn ion-implanter with beam energy of 160 keV. The PAC measurements were carried out with four BaF{sub 2} detector gamma spectrometer in the temperature range of 10-295 K. The results show no significant difference in the values of hyperfine parameters. Both techniques show practically the same electric quadrupole interaction for the substitutional site. The results were compared with previous PAC and Moessbauer measurements of SnO{sub 2} powder samples using {sup 111}In-{sup 111}Cd probe. (author)

  14. Negative muon spin precession measurement of the hyperfine states of muonic sodium

    International Nuclear Information System (INIS)

    Brewer, J.H.; Ghandi, K.; Froese, A.M.; Fryer, B.A.

    2005-01-01

    Both hyperfine states of muonic 23 Na and the rate R of conversion between them have been observed directly in a high field negative muon spin precession experiment using a backward muon beam with transverse spin polarization. The result in metallic sodium, R=13.7±2.2 μs -1 , is consistent with Winston's prediction in 1963 based on Auger emission of core electrons, and with the measurements of Gorringe et al. in Na metal, but not with their smaller result in NaF. In NaOH we find R=23.5±8 μs -1 , leaving medium-dependent effects ambiguous

  15. Application of the microcalorimetry to the study of annealing and recrystallization phenomena during the sintering of metallic powders

    International Nuclear Information System (INIS)

    Cytermann, R.; Mazadier, M.; Auguin, B.; Defresne, A.; Gilles, P.

    1975-01-01

    Nickel powders compressed isostatically at pressures between 1 and 13 kbars were studied. The tests were all carried out under a current of hydrogen after vacuum degassing and at the same temperature increase rate. Cold-hardening of the powders was shown by the broadening of the X-ray diffraction lines. Microcalorimetry confirmed the separation of the compacting process into two stages: rearrangement with local deformation and bulk plastic deformation [fr

  16. Experimental and ab initio study of the hyperfine parameters of ZnFe {sub 2}O{sub 4} with defects

    Energy Technology Data Exchange (ETDEWEB)

    Quintero, J. Melo; Salcedo Rodríguez, K. L.; Pasquevich, G. A.; Zélis, P. Mendoza; Stewart, S. J., E-mail: stewart@fisica.unlp.edu.ar; Rodríguez Torres, C. E.; Errico, L. A. [Universidad Nacional de La Plata, IFLP-CCT- La Plata-CONICET and Departamento de Física, Facultad de Ciencias Exactas, C. C. 67 (Argentina)

    2016-12-15

    We present a combined Mössbauer and ab initio study on the influence of oxygen-vacancies on the hyperfine and magnetic properties of the ZnFe {sub 2}O{sub 4} spinel ferrite. Samples with different degree of oxygen-vacancies were obtained from zinc ferrite powder that was thermally treated at different temperatures up to 650 {sup ∘}C under vacuum.Theoretical calculations of the hyperfine parameters, magnetic moments and magnetic alignment have been carried out considering different defects such as oxygen vacancies and cation inversion. We show how theoretical and experimental approaches are complementary to characterize the local structure around Fe atoms and interpret the observed changes in the hyperfine parameters as the level of defects increases.

  17. Hyperfine interaction measurements on ceramics: PZT revisited

    International Nuclear Information System (INIS)

    Guarany, Cristiano A.; Araujo, Eudes B.; Silva, Paulo R.J.; Saitovitch, Henrique

    2007-01-01

    The solid solution of PbZr 1- x Ti x O 3 , known as lead-zirconate titanate (PZT), was probably one of the most studied ferroelectric materials, especially due to its excellent dielectric, ferroelectric and piezoelectric properties. The highest piezoelectric coefficients of the PZT are found near the morphotropic phase boundary (MPB) (0.46≤x≤0.49), between the tetragonal and rhombohedral regions of the composition-temperature phase diagram. Recently, a new monoclinic phase near the MPB was observed, which can be considered as a 'bridge' between PZT's tetragonal and rhombohedral phases. This work is concerned with the study of the structural properties of the ferroelectric PZT (Zr/Ti=52/48, 53/47) by hyperfine interaction (HI) measurements obtained from experiments performed by using the nuclear spectroscopy time differential perturbed angular correlation (TDPAC) in a wide temperature range

  18. Hyperfine interactions in USb2 crystal

    International Nuclear Information System (INIS)

    Fathi, A.; Asadabadi, S. J.; Goshtasbi Rad, M.

    2006-01-01

    The hyperfine interactions at the uranium site in the antiferromagnetic USb 2 compound were calculated within the density functional theory employing the augmented plane wave plus local orbital (APW+1o) method. We investigated the dependence of the nuclear quadruple interactions on the magnetic structure in USb 2 compound. The investigation were performed applying the so called b and correlated L DA+U theory self consistently. The self consistent LDA+U calculations were gradually added to the performed generalized gradient approximation including scalar relativistic spin-orbit interactions in a second variation scheme. The result, which is in agreement with experiment, shows that the 5f-electrons have the tendency to be hybridized with the conduction electrons in the ferromagnetic uranium planes

  19. Predictive modeling, simulation, and optimization of laser processing techniques: UV nanosecond-pulsed laser micromachining of polymers and selective laser melting of powder metals

    Science.gov (United States)

    Criales Escobar, Luis Ernesto

    One of the most frequently evolving areas of research is the utilization of lasers for micro-manufacturing and additive manufacturing purposes. The use of laser beam as a tool for manufacturing arises from the need for flexible and rapid manufacturing at a low-to-mid cost. Laser micro-machining provides an advantage over mechanical micro-machining due to the faster production times of large batch sizes and the high costs associated with specific tools. Laser based additive manufacturing enables processing of powder metals for direct and rapid fabrication of products. Therefore, laser processing can be viewed as a fast, flexible, and cost-effective approach compared to traditional manufacturing processes. Two types of laser processing techniques are studied: laser ablation of polymers for micro-channel fabrication and selective laser melting of metal powders. Initially, a feasibility study for laser-based micro-channel fabrication of poly(dimethylsiloxane) (PDMS) via experimentation is presented. In particular, the effectiveness of utilizing a nanosecond-pulsed laser as the energy source for laser ablation is studied. The results are analyzed statistically and a relationship between process parameters and micro-channel dimensions is established. Additionally, a process model is introduced for predicting channel depth. Model outputs are compared and analyzed to experimental results. The second part of this research focuses on a physics-based FEM approach for predicting the temperature profile and melt pool geometry in selective laser melting (SLM) of metal powders. Temperature profiles are calculated for a moving laser heat source to understand the temperature rise due to heating during SLM. Based on the predicted temperature distributions, melt pool geometry, i.e. the locations at which melting of the powder material occurs, is determined. Simulation results are compared against data obtained from experimental Inconel 625 test coupons fabricated at the National

  20. The hyperfine properties of a hydrogenated Fe/V superlattice

    Energy Technology Data Exchange (ETDEWEB)

    Elzain, M., E-mail: elzain@squ.edu.om; Al-Barwani, M.; Gismelseed, A.; Al-Rawas, A.; Yousif, A.; Widatallah, H.; Bouziane, K.; Al-Omari, I. [Sultan Qaboos University, Department of Physics, College of Science (Oman)

    2012-03-15

    We study the effect of hydrogen on the electronic, magnetic and hyperfine structures of an iron-vanadium superlattice consisting of three Fe monolayers and nine V monolayers. The contact charge density ({rho}), the contact hyperfine field (B{sub hf}) and the electronic field gradient (EFG) at the Fe sites for different H locations and H fillings are calculated using the first principle full-potential linear-augmented-plane-wave (FP-LAPW) method. It is found that sizeable changes in the hyperfine properties are obtained only when H is in the interface region.

  1. Hyperfine structure of S-states of muonic tritium

    Directory of Open Access Journals (Sweden)

    Martynenko F.A.

    2017-01-01

    Full Text Available On the basis of quasipotential method in quantum electrodynamics we carry out a precise calculation of hyperfine splitting of S-states in muonic tritium. The one-loop and two-loop vacuum polarization corrections, relativistic effects, nuclear structure corrections in first and second orders of perturbation theory are taken into account. The contributions to hyperfine structure are obtained in integral form and calculated analytically and numerically. Obtained results for hyperfine splitting can be used for a comparison with future experimental data of CREMA collaboration.

  2. Structural properties and hyperfine characterization of Sn-substituted goethites

    Energy Technology Data Exchange (ETDEWEB)

    Larralde, A.L. [INQUIMAE, Departamento de Quimica Inorganica, Analitica y Quimica Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina); Ramos, C.P. [Departamento de Fisica de la Materia Condensada, GIyA - CAC - CNEA, Av. Gral. Paz 1499 (1650), San Martin, Bs. As. (Argentina); Arcondo, B. [Departamento de Fisica, Facultad de Ingenieria, Universidad de Buenos Aires, Av. Paseo Colon 850 (C1063ACV), Bs. As. (Argentina); Tufo, A.E. [INQUIMAE, Departamento de Quimica Inorganica, Analitica y Quimica Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina); Saragovi, C. [Departamento de Fisica de la Materia Condensada, GIyA - CAC - CNEA, Av. Gral. Paz 1499 (1650), San Martin, Bs. As. (Argentina); Sileo, E.E., E-mail: sileo@qi.fcen.uba.ar [INQUIMAE, Departamento de Quimica Inorganica, Analitica y Quimica Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina)

    2012-04-16

    Highlights: Black-Right-Pointing-Pointer Pure and tin-doped goethites were synthesized from Sn(II) solutions at ambient pressure and 70 Degree-Sign C. Black-Right-Pointing-Pointer The Rietveld refinement of PXRD data indicated that Sn partially substituted the Fe(III) ions. Black-Right-Pointing-Pointer The substitution provoked unit cell expansion, and a distortion of the coordination polyhedron. Black-Right-Pointing-Pointer {sup 119}Sn Moessbauer spectroscopy revealed that Sn(II) is incorporated as Sn(IV). Black-Right-Pointing-Pointer {sup 57}Fe Moessbauer spectroscopy showed a lower magnetic coupling as tin concentration increased. - Abstract: Tin-doped goethites obtained by a simple method at ambient pressure and 70 Degree-Sign C were characterized by inductively coupled plasma atomic emission spectrometry, scanning electron microscopy, Rietveld refinement of powder X-ray diffraction data, and {sup 57}Fe and {sup 119}Sn Moessbauer spectroscopy. The particles size and the length to width ratios decreased with tin-doping. Sn partially substituted the Fe(III) ions provoking unit cell expansion and increasing the crystallinity of the particles with enlarged domains that grow in the perpendicular and parallel directions to the anisotropic broadening (1 1 1) axis. Intermetallic E, E Prime and DC distances also change although the variations are not monotonous, indicating different variations in the coordination polyhedron. In general, the Sn-substituted samples present larger intermetallic distances than pure goethite, and the greatest change is shown in the E Prime distance which coincides with the c-parameter. {sup 119}Sn Moessbauer spectroscopy revealed that Sn(II) is incorporated as Sn(IV) in the samples. On the other hand, Fe(II) presence was not detected by {sup 57}Fe Moessbauer spectroscopy, suggesting the existence of vacancies in the Sn-doped samples. A lower magnetic coupling is also evidenced from the average magnetic hyperfine field values obtained as tin

  3. Electrical detection of hyperfine interactions in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Hoehne, Felix

    2012-12-15

    The main focus of this work was the measurement of hyperfine interactions of defects in silicon using EDMR. We combined the high sensitivity of EDMR when compared to conventional ESR with the two most commonly used methods for the measurement of hyperfine interactions: ESEEM and ENDOR. We first demonstrated the electrical detection of ESEEM by measuring the hyperfine interactions of {sup 31}P donors in Si:P with {sup 29}Si nuclear spins. We then apply EDESEEM to P{sub b0} defects at the Si/SiO{sub 2} interface. In isotopically engineered, we observe an ESEEM modulation with a characteristic beating caused by {sup 29}Si nuclei at 4th and 5th nearest neighbor lattice sites. Then we combine pulsed ENDOR with the high sensitivity of EDMR (EDENDOR). First we demonstrate the measurement of {sup 31}P nuclear spin hyperfine transitions and the coherent manipulation and readout of the {sup 31}P nuclear spins under continuous illumination with above bandgap light. We further show that the EDENDOR method can be greatly improved by switching off the illumination during the microwave and rf pulses. This improves the signal-to-noise ratio by two orders of magnitude and removes the non-resonant background induced by the strong rf pulse allowing to measure ENDOR with a sensitivity <3000 nuclear spins. We apply EDENDOR to the {sup 31}P-P{sub b0} spin system and the {sup 31}P-SL1 spin system allowing us to compare the hyperfine interactions of bulk and interface-near donors. The pulsed illumination also makes spectroscopy of the {sup 31}P{sup +} nuclear spin possible, which due to its long coherence time of 18 ms compared to 280 {mu}s for the {sup 31}P{sub 0} nuclear spin, might be a candidate for a nuclear spin memory. In the last part, we devise a scheme for the hyperpolarization of {sup 31}P nuclei by combining pulsed optical excitation and pulsed ENDOR and demonstrate a {sup 31}P nuclear spin polarization of more than 50%. Crucial for these experiments was the development of a

  4. Electrical detection of hyperfine interactions in silicon

    International Nuclear Information System (INIS)

    Hoehne, Felix

    2012-01-01

    The main focus of this work was the measurement of hyperfine interactions of defects in silicon using EDMR. We combined the high sensitivity of EDMR when compared to conventional ESR with the two most commonly used methods for the measurement of hyperfine interactions: ESEEM and ENDOR. We first demonstrated the electrical detection of ESEEM by measuring the hyperfine interactions of 31 P donors in Si:P with 29 Si nuclear spins. We then apply EDESEEM to P b0 defects at the Si/SiO 2 interface. In isotopically engineered, we observe an ESEEM modulation with a characteristic beating caused by 29 Si nuclei at 4th and 5th nearest neighbor lattice sites. Then we combine pulsed ENDOR with the high sensitivity of EDMR (EDENDOR). First we demonstrate the measurement of 31 P nuclear spin hyperfine transitions and the coherent manipulation and readout of the 31 P nuclear spins under continuous illumination with above bandgap light. We further show that the EDENDOR method can be greatly improved by switching off the illumination during the microwave and rf pulses. This improves the signal-to-noise ratio by two orders of magnitude and removes the non-resonant background induced by the strong rf pulse allowing to measure ENDOR with a sensitivity 31 P-P b0 spin system and the 31 P-SL1 spin system allowing us to compare the hyperfine interactions of bulk and interface-near donors. The pulsed illumination also makes spectroscopy of the 31 P + nuclear spin possible, which due to its long coherence time of 18 ms compared to 280 μs for the 31 P 0 nuclear spin, might be a candidate for a nuclear spin memory. In the last part, we devise a scheme for the hyperpolarization of 31 P nuclei by combining pulsed optical excitation and pulsed ENDOR and demonstrate a 31 P nuclear spin polarization of more than 50%. Crucial for these experiments was the development of a lock-in detection scheme for pEDMR, which improves the signal-to-noise ratio by one order of magnitude by removing low

  5. Study of hyperfine interactions in V2O3 by angular correlation

    International Nuclear Information System (INIS)

    Jesus Silva, P.R. de.

    1985-01-01

    The hyperfine interaction in v 2 O 3 in function of temperature by measurements of time differential perturbed angular correlation is studied. The samples presented quadrupole interaction in the probe center, Cd 111 immediatelly after sintering, when reduced in H 2 flux at 800 0 C. A pure electric quadrupole interaction at the metallic phase and a combined interaction of magnetic dipole and electric quadrupole at the insulating antiferromagnetic phase, were observed. The electric field gradient undergoes abrupt variation at the metal-insulating transition at T=160 0 K from 8.2x10 17 v/cm 2 at the insulating phase to 6.3x10 17 v/cm 2 in the metallic phase, however varies smoothly with the temperature at T=450 0 K when variations in resistivity also occur. At metallic phase the electric field increases with the temperature enhacement. The hyperfine magnetic field of Cd 111 at antiferromagnetic phase of V 2 O 3 has a saturation value of 15(1) KOe and performes an angle of β=68(2) 0 with the main component direction of electric field gradient. (M.C.K.) [pt

  6. Metallic glasses

    NARCIS (Netherlands)

    Schaafsma, Arjen Sybren

    1981-01-01

    It is shown in section 7.1. that the influence of topological disorder on the range of magnetic interactions in ferromagnetic transition metal-metalloid (TM-M) glasses, is much less than often assumed. This is demonstrated via a study of the temperature dependence of the average iron hyperfine field

  7. Experimental Constraints on Polarizability Corrections to Hydrogen Hyperfine Structure

    International Nuclear Information System (INIS)

    Nazaryan, Vahagn; Carlson, Carl E.; Griffioen, Keith A.

    2006-01-01

    We present a state-of-the-art evaluation of the polarizability corrections--the inelastic nucleon corrections--to the hydrogen ground-state hyperfine splitting using analytic fits to the most recent data. We find a value Δ pol =1.3±0.3 ppm. This is 1-2 ppm smaller than the value of Δ pol deduced using hyperfine splitting data and elastic nucleon corrections obtained from modern form factor fits

  8. Effect of powder density variation on premixed Ti-6Al-4 V and Cu composites during laser metal deposition

    CSIR Research Space (South Africa)

    Erinosho, MF

    2016-05-01

    Full Text Available This paper reports the effect of powder density variation on the premixed Ti-6Al-4 V/Cu and Ti-6A-4 V/2Cu Composites. Two sets of experiment were conducted in this study. Five deposits each were made for the two premixed composites. Laser powers were...

  9. Gas flow rate and powder flow rate effect on properties of laser metal deposited Ti6Al4V

    CSIR Research Space (South Africa)

    Pityana, S

    2013-03-01

    Full Text Available . The powder flow rate and the gas flow rate were varied to study their effect on the physical, metallurgical and mechanical properties of the deposits. The physical properties studied are: the track width, the track height and the deposit weight...

  10. Proceedings of the 2nd KUR symposium on hyperfine interactions

    International Nuclear Information System (INIS)

    Mekata, M.; Minamisono, T.; Kawase, Y.

    1991-10-01

    Hyperfine interactions between a nuclear spin and an electronic spin discovered from hyperfine splitting in atomic optical spectra have been utilized not only for the determination of nuclear parameters in nuclear physics but also for novel experimental techniques in many fields such as solid state physics, chemistry, biology, mineralogy and for diagnostic methods in medical science. Experimental techniques based on hyperfine interactions yield information about microscopic states of matter so that they are important in material science. Probes for material research using hyperfine interactions have been nuclei in the ground state and radioactive isotopes prepared with nuclear reactors or particle accelerators. But utilization of muons generated from accelerators is recently growing. Such wide spread application of hyperfine interaction techniques gives rise to some difficulty in collaboration among various research fields. In these circumstances, the present workshop was planned after four years since the last KUR symposium on the same subject. This report summarizes the contributions to the workshop in order to be available for the studies of hyperfine interactions. (J.P.N.)

  11. ESTABLISHING SUSTAINABLE US HEV/PHEV MANUFACTURING BASE: STABILIZED LITHIUM METAL POWDER, ENABLING MATERIAL AND REVOLUTIONARY TECHNOLOGY FOR HIGH ENERGY LI-ION BATTERIES

    Energy Technology Data Exchange (ETDEWEB)

    Yakovleva, Marina

    2012-12-31

    FMC Lithium Division has successfully completed the project “Establishing Sustainable US PHEV/EV Manufacturing Base: Stabilized Lithium Metal Powder, Enabling Material and Revolutionary Technology for High Energy Li-ion Batteries”. The project included design, acquisition and process development for the production scale units to 1) produce stabilized lithium dispersions in oil medium, 2) to produce dry stabilized lithium metal powders, 3) to evaluate, design and acquire pilot-scale unit for alternative production technology to further decrease the cost, and 4) to demonstrate concepts for integrating SLMP technology into the Li- ion batteries to increase energy density. It is very difficult to satisfy safety, cost and performance requirements for the PHEV and EV applications. As the initial step in SLMP Technology introduction, industry can use commercially available LiMn2O4 or LiFePO4, for example, that are the only proven safer and cheaper lithium providing cathodes available on the market. Unfortunately, these cathodes alone are inferior to the energy density of the conventional LiCoO2 cathode and, even when paired with the advanced anode materials, such as silicon composite material, the resulting cell will still not meet the energy density requirements. We have demonstrated, however, if SLMP Technology is used to compensate for the irreversible capacity in the anode, the efficiency of the cathode utilization will be improved and the cost of the cell, based on the materials, will decrease.

  12. Microstructure and High Temperature Oxidation Property of Fe-Cr-B Based Metal/Ceramic Composite Manufactured by Powder Injection Molding Process

    Science.gov (United States)

    Joo, Yeun-Ah; Kim, Young-Kyun; Yoon, Tae-Sik; Lee, Kee-Ahn

    2018-02-01

    This study investigated the microstructure and high temperature oxidation property of Fe-Cr-B metal/ceramic composite manufactured using powder injection molding process. Observations of initial microstructure showed a unique structure where α-Fe and (Cr, Fe)2B form a continuous three-dimensional network. High temperature oxidation tests were performed at 900, 1000 and 1100 °C, for 24 h, and the oxidation weight gain according to each temperature condition was 0.13, 0.84 and 6.4 mg/cm2, respectively. The oxidation results according to time at 900 and 1000 °C conditions represented parabolic curves, and at 1100 °C condition formed a rectilinear curve. Observation and phase analysis results of the oxides identified Cr2O3 and SiO2 at 900 and 1000 °C. In addition to Cr2O3 and SiO2, CrBO3 and FeCr2O4 formed due to phase decomposition of boride were identified at 1100 °C. Based on the findings above, this study suggested the high temperature oxidation mechanism of Fe-Cr-B metal/ceramic composite manufactured using powder injection molding, and the possibility of its application as a high temperature component material was also discussed.

  13. Microstructure and High Temperature Oxidation Property of Fe-Cr-B Based Metal/Ceramic Composite Manufactured by Powder Injection Molding Process

    Science.gov (United States)

    Joo, Yeun-Ah; Kim, Young-Kyun; Yoon, Tae-Sik; Lee, Kee-Ahn

    2018-03-01

    This study investigated the microstructure and high temperature oxidation property of Fe-Cr-B metal/ceramic composite manufactured using powder injection molding process. Observations of initial microstructure showed a unique structure where α-Fe and (Cr, Fe)2B form a continuous three-dimensional network. High temperature oxidation tests were performed at 900, 1000 and 1100 °C, for 24 h, and the oxidation weight gain according to each temperature condition was 0.13, 0.84 and 6.4 mg/cm2, respectively. The oxidation results according to time at 900 and 1000 °C conditions represented parabolic curves, and at 1100 °C condition formed a rectilinear curve. Observation and phase analysis results of the oxides identified Cr2O3 and SiO2 at 900 and 1000 °C. In addition to Cr2O3 and SiO2, CrBO3 and FeCr2O4 formed due to phase decomposition of boride were identified at 1100 °C. Based on the findings above, this study suggested the high temperature oxidation mechanism of Fe-Cr-B metal/ceramic composite manufactured using powder injection molding, and the possibility of its application as a high temperature component material was also discussed.

  14. Theory of hyperfine anomalies in muonic atoms

    International Nuclear Information System (INIS)

    Freeman, A.J.; Desclaux, J.P.

    1984-01-01

    Negative muon spin precession experiments have found giant hyperfine anomalies in muonic atoms ranging from a few percent up to 36%. In order to understand these results, the authors present Breit interaction calculations based on atomic self-consistent unrestricted Dirac-Fock solutions which explicitly include all electrons and the negative muon. The Breit interaction results (including the relativistic correction for the bound muon g-factor), vary from near zero for μ - O/N to -5% for μ - Pd/Rh; this latter is much larger than the calculated muonic or nuclear Bohr-Weisskopf anomalies and much smaller than the 36% measured value. For μ - Ni/Co the authors find a calculated range of results (depending on assumed electronic configurations) of -2.3 to -2.7% in excellent agreement with recent measurements. This excellent agreement in μ - Ni/Co provides strong support for the earlier suggestions that the discrepancy in the case of μ - Pd/Rh is due to experimental factors. (Auth.)

  15. Niobium hyperfine structure in crystal calcium tungstate

    Science.gov (United States)

    Tseng, D. L.; Kikuchi, C.

    1972-01-01

    A study of the niobium hyperfine structure in single crystal calcium tungstate was made by the combination of the technique of electron paramagnetic resonance and electron nuclear double resonance (EPR/ENDOR). The microwave frequency was about 9.4 GHz and the radio frequency from 20MHz to 70 MHz. The rare earth ions Nd(3+), U(3+), or Tm(3+) were added as the charge compensator for Nb(5+). To create niobium paramagnetic centers, the sample was irradiated at 77 deg K with a 10 thousand curie Co-60 gamma source for 1 to 2 hours at a dose rate of 200 K rads per hour and then transferred quickly into the cavity. In a general direction of magnetic field, the spectra showed 4 sets of 10 main lines corresponding to 4 nonequivalent sites of niobium with I = 9/2. These 4 sets of lines coalesced into 2 sets of 10 in the ab-plane and into a single set of 10 along the c-axis. This symmetry suggested that the tungsten ions are substituted by the niobium ions in the crystal.

  16. Hyperfine structure and Λ doubling in the A 2Δ state of CH : Observation of an internal hyperfine perturbation

    NARCIS (Netherlands)

    Ubachs, Wim; Van Herpen, W. M.; ter Meulen, J.J.; Dymanus, A.

    1986-01-01

    We report the observation of a resonance between hyperfine states, due to the crossing of rotational ladders at N=10 of Δ5/2 and Δ3/2 spin-doublet states in the excited A 2Δ state of CH. Accurate values for the hyperfine constants a, b, and c in the A 2Δ state were obtained. From measurements of the

  17. A practical approach for solving disposal of rubber waste: Leachability of heavy metals from foamed concrete containing rubber powder waste (RPW)

    Science.gov (United States)

    Kadir, Aeslina Abdul; Hassan, Mohd Ikhmal Haqeem; Sarani, Noor Amira; Yatim, Fatin Syahirah Mohamed; Jaini, Zainorizuan Mohd

    2017-09-01

    Enormous disposal of rubber wastes has become an issue with the facts that all tires have its own life span. Inefficient disposal method of RPW from used tire can cause environmental impact as the heavy metals content in tire can easily leach out thus causing contamination to the soil and waterways. The goals of this study is to identify the heavy metals content of rubber powder waste (RPW) and to determine the potential of leachability of heavy metals from foamed concrete containing different percentages of RPW. Therefore, this study is focused on the leachability of RPW incorporated in foamed concrete. Different percentages of RPW were incorporated in foamed concrete (0%, 6%, 12% and 18%) for the investigation. Leachability tests were done by using toxicity characteristic leaching procedure (TCLP) on crushed samples of foamed concrete incorporated with RPW and were analyzed by using inductive coupled plasma mass spectrometry (ICP-MS). The results from XRF indicated that RPW is high in metals such as Zn, Cu, Ba and Co. The highest concentration of heavy metals in raw RPW is Zn with 51403 ppm which is exceeded USEPA (2010) maximum contaminant level (MCL) of Zn with only 5 ppm. After RPW had been incorporated into a foamed concrete, the results demonstrated that the Zn, Cu, Ba and Co heavy metals were less leached and complied with USEPA standard. The incorporation of RPW into foamed concrete in this study demonstrated that it could be a potential alternative raw material for concrete thus enhancing the possibility of its reuse in safe and sustainable way.

  18. Preparation of granular activated carbons from composite of powder activated carbon and modified β-zeolite and application to heavy metals removal.

    Science.gov (United States)

    Seyedein Ghannad, S M R; Lotfollahi, M N

    2018-03-01

    Heavy metals are continuously contaminating the surface and subsurface water. The adsorption process is an attractive alternative for removing the heavy metals because of its low cost, simple operation, high efficiency, and flexible design. In this study, influences of β-zeolite and Cu-modified β-zeolite on preparation of granular activated carbons (GACs) from a composite of powder activated carbon (PAC), methylcellulose as organic binder, bentonite as inorganic binder, and water were investigated. A number of granular samples were prepared by controlling the weight percentage of binder materials, PAC and zeolites as a reinforcing adsorbent. Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction techniques were employed to characterize zeolite, modified zeolite and produced GAC. The produced GACs were used as the adsorbent for removal of Zn +2 , Cd 2+ and Pb 2+ ions from aqueous solutions. The results indicated that the adsorption of metals ions depended on the pH (5.5) and contact time (30 min). Maximum adsorption of 97.6% for Pb 2+ , 95.9% for Cd 2+ and 91.1% for Zn +2 occurred with a new kind of GAC made of Cu-modified β-zeolite. The Zn +2 , Cd 2+ and Pb 2+ ions sorption kinetics data were well described by a pseudo-second order model for all sorbents. The Langmuir and Freundlich isotherm models were applied to analyze the experimental equilibrium data.

  19. Equal channel angular pressing of powder processed Al6061/SiC nano metal matrix composites and study of its wear properties

    Science.gov (United States)

    Bongale, Arunkumar M.; Kumar, Satish

    2018-03-01

    Nano Metal Matrix Composites were fabricated by a novel approach by combining powder metallurgy and equal channel angular pressing (ECAP) using aluminium alloy 6061 (Al6061) as matrix phase and 2, 4 and 6 wt% of silicon carbide nanoparticles (SiCnp) as reinforcements. Alloying elements of Al6061 in their elemental form are blended together using high energy planetary ball mill and calculated wt% of SiCnp were mixed with it. Thus formed composite powder mixture is compacted in a uniaxial compaction die and then subjected to ECAP up to three passes. Density and porosity of samples were estimated using Archimedes’ principle. Pin on disc setup is used to evaluate the wear properties of the composites under different speed and loading conditions. Tests revealed that increase in wt% of SiCnp reduces the wear rate of the composites whereas increasing the load and speed increases wear rate of the composite samples. SEM micrographs of worn surfaces indicated different types of wear mechanism responsible for wear of the specimens under different testing conditions. Also, wt% of SiCnp and the number of passes through ECAP were found to increase the hardness value of the composite material.

  20. Synthesis and luminescence properties of ZnS and metal (Mn, Cu)-doped-ZnS ceramic powder

    Science.gov (United States)

    Ummartyotin, S.; Bunnak, N.; Juntaro, J.; Sain, M.; Manuspiya, H.

    2012-03-01

    ZnS and metal (Mn, Cu)-doped-ZnS were successfully prepared by wet chemical synthetic route. The understanding of substituted metal ions (Mn, Cu) into ZnS leads to transfer the luminescent centre by small amount of metal dopant (Mn, Cu). Fourier transform infrared and X-ray diffraction were used to determine chemical bonding and crystal structure, respectively. It showed that small amount of metal (Mn, Cu) can be completely substituted into ZnS lattice. X-ray fluorescence was used to confirm the existence of metal-doped ZnS. Scanning electron microscope revealed that their particles exhibits blocky particle with irregular sharp. Laser confocal microscope and photoluminescence spectroscopy showed that ZnS and metal-doped-ZnS exhibited intense, stable, and tunable emission covering the blue to red end of the visible spectrum. ZnS, Mn-doped-ZnS and Cu-doped-ZnS generated blue, yellow and green color, respectively.

  1. Surface fatigue and failure characteristics of hot-forged powder metal AISI 4620, AISI 4640, and machined AISI 4340 steel spur gears

    Science.gov (United States)

    Townsend, Dennis P.

    1987-01-01

    Spur gear surface fatigue endurance tests were conducted to investigate hot forged powder metal AISI 4620 and 4640 steel for use as a gear material, to determine endurance characteristics and to compare the results with machined AISI 4340 and 9310 steel gear materials. The as-forged and unground AISI 4620 gear exhibited a 10 percent fatigue life that was approximately one-fourth of that for AISI 9310 and less than one-half that for the AISI 4340 gears. The forged and finish ground AISI 4620 gears exhibited a 10 percent life, approximately 70 percent that of AISI 9310 and slightly better than that of AISI 4340. The AISI 4640 hot forged gears had less fracture toughness and slightly less fatigue life than the AISI 4620 test gears.

  2. Surface fatigue and failure characteristics of hot forged powder metal AISI 4620, AISI 4640, and machined AISI 4340 steel spur gears

    Science.gov (United States)

    Townsend, D. P.

    1986-01-01

    Spur gear surface fatigue endurance tests were conducted to investigate hot forged powder metal AISI 4620 and 4640 steel for use as a gear material, to determine endurance characteristics and to compare the results with machined AISI 4340 and 9310 steel gear materials. The as-forged and unground SISI 4620 gear exhibited a 10 percent fatigue life that was approximately one-fourth of that for AISI 9310 and less than one-half that for the AISI 4340 gears. The forged and finish ground AISI 4620 gears exhibited a 10 percent life, approximately 70 percent that of AISI 9310 and slightly better than that of AISI 4340. The AISI 4640 hot forged gears had less fracture toughness and slightly less fatigue life than the AISI 4620 test gears.

  3. Sinterable powders

    International Nuclear Information System (INIS)

    Zanghi, J.S.; Kasprzyk, M.R.

    1979-01-01

    A description is given of sinterable powders and methods of producing sintered products using such powders. The powders consist of (a) a particulate ceramic material, e.g. SiC, having specified particle size and surface area; (b) a carbon source material, e.g. sugar or a phenol-formaldehyde resin; and (c) a residue from a solution of H 3 BO 3 , B 2 O 3 , or mixtures of these as sintering aid. (U.K.)

  4. Hyperfine structure of positronium energy levels in a crystal

    International Nuclear Information System (INIS)

    Bondarev, I.V.; Kuten, S.A.

    1993-07-01

    Hyperfine structure of positronium energy levels in crystal solids with noncubic lattice is considered. It is shown that due to the hyperfine interaction between the electron and the positron positronium atom in a crystal can have effective quadrupole moment and tensor polarizability. In such a case the effective quadrupole interaction with intracrystalline fields leads to the quadrupole splitting of triplet level and also to the positronium magnetic quenching anisotropy in the presence of external magnetic field. The possibilities of experimental observation of such anisotropy are discussed. (author). 26 refs, 1 fig

  5. Photon Doppler Velocimeter to Measure Entrained Additive Manufactured Bulk Metal Powders in Hot Subsonic and Supersonic Oxygen Gas

    Science.gov (United States)

    Tylka, Jonathan

    2016-01-01

    Parts produced by additive manufacturing, particularly selective laser melting (SLM), have been shown to silt metal particulate even after undergoing stringent precision aerospace cleaning processes (Lowrey 2016). As printed parts are used in oxygen systems with increased pressures, temperatures, and gas velocity, the risk of ignition by particle impact, the most common direct ignition source of metals in oxygen, substantially increases. The White Sands Test Facility (WSTF), in collaboration with Marshall Space Flight Center (MSFC), desires to test the ignitability of SLM metals by particle impact in heated oxygen. The existing test systems rely on gas velocity calculations to infer particle velocity in both subsonic and supersonic particle impact systems. Until now, it was not possible to directly measure particle velocity. To increase the fidelity of planned SLM ignition studies, it is necessary to validate that the Photon Doppler Velocimetry(PDV) test system can accurately measure particle velocity.

  6. Mössbauer studies of hyperfine fields in disordered Fe CrAl

    Indian Academy of Sciences (India)

    magnetic hyperfine field, the average hyperfine field follows the ´T Tcµ3 2 law. The paramagnetic part of the hyperfine field is explained in terms of the clustering of Cr ... These alloys offer excellent systems for studying magnetic interactions. Large volumes of studies have been devoted to Heusler alloys bearing the general ...

  7. Three diverse solid phenolics with similar hyperfine EPR spectra - why?

    International Nuclear Information System (INIS)

    Troup, G.J.; Drew, S.; Hutton, D.R.; Pilbrow, J.R.; Hewitt, D.G.

    2002-01-01

    Full text: Among the 50 or so solid phenolics we have studied by EPR, only three have given evidence of hyperfine structure, and the spectra are quite similar, with two lesser lines symmetrically placed about a higher central line. The specimens were: a phenolic extract of green tea (Indena, S.p.a.), mainly epigallocatechin gallate; an extract of shiraz grapeseeds, mainly (-) epicatechin - 3 - O - gallate and its dimers and polymers, and a sample of 95% pure hesperidin. The commercially available grapeseed extracts Pycnogenol(R) and 'OPC'S' showed no EPR hyperfine structure. At low modulation levels for hesperidin, the two outer lines each split into two, but this did not happen for the other samples. The mean spacing of the outer lines from the central one was different for each sample. At 77 K, a Cu(2+) signal was detected in the grapeseed extract, but had become motionally broadened before room temperature, so could not contribute to the free radical signal: Cu (2+) was not detected in the other samples at 77K. Preparational details were only available for the grapeseed extract, since the other samples were commercial products. For the hyperfine structure to be seen, there must be a distinct anisotropy in the materials, rather than a glass-like structure. Is it crystallisation, or strain? We would welcome suggestions for the cause of the hyperfine structure becoming visible, and the similarity of the spectra

  8. Hyperfine coupling constants in muonium adducts of the carbonyl bond

    International Nuclear Information System (INIS)

    Cox, S.F.J.; Scott, C.A.; Geeson, D.A.; Rhodes, C.J.; Symons, M.C.R.; Roduner, E.

    1986-01-01

    A representative series is studied of organic radicals formed by the effective addition of muonium to the carbonyl oxygen atom of aldehydes, ketones, esters and amides. Low values of the muon-electron hyperfine coupling are measured which are particularly sensitive to radical structure and dynamics. The systematics of these values are discussed in terms of the opposing contributions of conjugation and hyperconjugation. (orig.)

  9. Muon zero point motion and the hyperfine field in nickel

    International Nuclear Information System (INIS)

    Elzain, M.E.

    1984-09-01

    It is argued that the effect of zero point motion of muons in Ni is to induce local vibrations of the neighbouring Ni atoms. This local vibration reduces the Hubbard correlation and hence decreases the net spin per atom. This acts back to reduce the hyperfine field at the muon site. (author)

  10. A new strategy for pressed powder eye shadow analysis: allergenic metal ion content and particle size distribution.

    Science.gov (United States)

    Contado, Catia; Pagnoni, Antonella

    2012-08-15

    Nine cheap eye shadow products were analyzed through graphite furnace atomic absorption spectrometry (GF-AAS) to quantify their Cr, Co and Ni contents, all known to be skin sensitizers. In many cases, the concentrations were higher than 1 or 5 ppm (μg/g), i.e. the limits recommended in the scientific literature to minimize the risk of reaction in particularly sensitive subjects. In most cases, the concentration of Cr was higher than that of Ni and Co, up to a limit case of 150 mg/g. In this particular sample, the potential amount of Cr that could be released in ionic form was determined in sweat simulating solutions by GF-AAS and confirmed through a specific spectrofluorimetric method; the results indicated the presence of approximately 80-90 ppb (ng/g) of Cr(3+). The water dispersible particles were isolated from the eye shadow powders through a simple solvent extraction procedure. The aqueous suspensions were then sorted through sedimentation field flow fractionation (SdFFF) and the particles sizes were calculated from experimental fractograms using theory. For the most part, the computed sizes were in the micron range, as confirmed by some SEM photographs taken on fractions collected during the separations. The SdFFF coupled off-line with the GFAAS enabled elemental characterization of pigment particles as a function of size. This finding reduces the concern that the ingredients of such makeup formulations may contain nanoparticles. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. 27Al, 63Cu NMR spectroscopy and electrical transport in Heusler Cu-Mn-Al alloy powders

    Science.gov (United States)

    Nadutov, V. M.; Perekos, A. O.; Kokorin, V. V.; Trachevskii, V. V.; Konoplyuk, S. M.; Vashchuk, D. L.

    2018-02-01

    The ultrafine powder of the Heusler Cu-13,1Mn-12,6Al (wt.%) alloy produced by electrical spark dispersion (ESD) in ethanol and the pellets prepared by pressing of the powders and aged in various gas environment (air, Ar, vacuum) were studied by XRD, nuclear magnetic resonance, magnetic and electric transport methods. The constituent phases were identified as b.c.c. α-Cu-Mn-Al, f.c.c. γ-Cu-Mn-Al, Cu2MnAl, and oxides. The sizes of the coherently scattering domains (CSD) and the saturation magnetizations were in the range of 4-90 nm and 0-1.5 Am2/kg, respectively. 27Al and 63Cu NMR spectra of the powders and pellets have shown hyperfine structure caused by contributions from atomic nuclei of the constituent phases. The aging of pellets in different gas environments had effect on their phase composition but no effect on dispersion of the phases. In contrast to the as-cast alloy, electrical resistance of the pellets evidenced semiconducting behavior at elevated temperatures due to the presence of metal oxides formed on the surfaces of nanoparticles.

  12. Theory of long-range interactions for Rydberg states attached to hyperfine-split cores

    Science.gov (United States)

    Robicheaux, F.; Booth, D. W.; Saffman, M.

    2018-02-01

    The theory is developed for one- and two-atom interactions when the atom has a Rydberg electron attached to a hyperfine-split core state. This situation is relevant for some of the rare-earth and alkaline-earth atoms that have been proposed for experiments on Rydberg-Rydberg interactions. For the rare-earth atoms, the core electrons can have a very substantial total angular momentum J and a nonzero nuclear spin I . In the alkaline-earth atoms there is a single (s ) core electron whose spin can couple to a nonzero nuclear spin for odd isotopes. The resulting hyperfine splitting of the core state can lead to substantial mixing between the Rydberg series attached to different thresholds. Compared to the unperturbed Rydberg series of the alkali-metal atoms, the series perturbations and near degeneracies from the different parity states could lead to qualitatively different behavior for single-atom Rydberg properties (polarizability, Zeeman mixing and splitting, etc.) as well as Rydberg-Rydberg interactions (C5 and C6 matrices).

  13. Synthesis of nanoparticles from malleable and ductile metals using powder-free, reactant-assisted mechanical attrition.

    Science.gov (United States)

    McMahon, Brandon W; Perez, Jesus Paulo L; Yu, Jiang; Boatz, Jerry A; Anderson, Scott L

    2014-11-26

    A reactant-assisted mechanochemical method was used to produce copious nanoparticles from malleable/ductile metals, demonstrated here for aluminum, iron, and copper. The milling media is intentionally degraded via a reactant-accelerated wear process, where the reactant aids particle production by binding to the metal surfaces, enhancing particle production, and reducing the tendency toward mechanochemical (cold) welding. The mechanism is explored by comparing the effects of different types of solvents and solvent mixtures on the amount and type of particles produced. Particles were functionalized with oleic acid to aid in particle size separation, enhance dispersion in hydrocarbon solvents, and protect the particles from oxidation. For aluminum and iron, the result is air-stable particles, but for copper, the suspended particles are found to dissolve when exposed to air. Characterization was performed using electron microscopy, dynamic light scattering, Fourier transform infrared spectroscopy, solid state nuclear magnetic resonance, and X-ray photoelectron spectroscopy. Density functional theory was used to examine the nature of carboxylic acid binding to the aluminum surface, confirming the dominance of bridging bidentate binding.

  14. Preparation of superconductor precursor powders

    Science.gov (United States)

    Bhattacharya, Raghunath; Blaugher, Richard D.

    1995-01-01

    A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals, such as nitrate salts of thallium, barium, calcium, and copper, which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of thallium in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products.

  15. The delayed lung responses to single and repeated intratracheal administration of pure cobalt and hard metal powder in the rat.

    Science.gov (United States)

    Lasfargues, G; Lardot, C; Delos, M; Lauwerys, R; Lison, D

    1995-05-01

    Epidemiological and clinical studies suggest that inhalation of cobalt metal dust (Co) mixed with tungsten carbide particles (WC), but not of cobalt dust alone, may cause interstitial pulmonary lesions (hard metal disease). In previous experimental studies in the rat, we have demonstrated the greater acute pulmonary toxicity of a WC-Co mixture compared to Co or WC alone. The present study was undertaken to compare in the same animal model the delayed lung response after intratracheal administration of Co or WC-Co particles (cobalt particle 6.3 wt%). The responses were also compared with those obtained after treatment with arsenic trioxide and crystalline silica used a reference materials producing an acute toxic insult and a progressive fibrogenic response, respectively. Cellular (total and differential counts) and biochemical parameters (LDH, N-acetyl-beta-D-glucosaminidase, total protein, albumin, fibronectin, and hyaluronic acid) were measured in bronchoalveolar lavage fluid following single and repeated intratracheal instillations. The results indicate that the delayed lung response observed after WC-Co is different from that after cobalt metal alone. A single intratracheal dose of WC-Co (1, 5, or 10 mg/100 g body wt) induced an acute alveolitis which persisted for at least 1 month. Four months after a single instillation of WC-Co, no clear histological lung fibrosis could however be evidenced, indicating a reversibility of the lesions. The effects of cobalt (0.06, 0.3, or 0.6 mg/100 g body wt) or tungsten carbide alone (1, 5, 10 mg/ 100 g body wt) were very modest, if any. Following repeated intratracheal instillations (four administrations at 1-month interval), increased lung hydroxyproline content and histopathological evidence of interstitial fibrosis were observed after WC-Co (4 x 1 mg/100 g body wt), but not after administration of each component separately, i.e., Co (4 x 0.06 mg/100 g body wt) or WC (4 x 1 mg/100 g body wt). The mechanism of the fibrotic

  16. Laser and electron-beam powder-bed additive manufacturing of metallic implants: A review on processes, materials and designs.

    Science.gov (United States)

    Sing, Swee Leong; An, Jia; Yeong, Wai Yee; Wiria, Florencia Edith

    2016-03-01

    Additive manufacturing (AM), also commonly known as 3D printing, allows the direct fabrication of functional parts with complex shapes from digital models. In this review, the current progress of two AM processes suitable for metallic orthopaedic implant applications, namely selective laser melting (SLM) and electron beam melting (EBM) are presented. Several critical design factors such as the need for data acquisition for patient-specific design, design dependent porosity for osteo-inductive implants, surface topology of the implants and design for reduction of stress-shielding in implants are discussed. Additive manufactured biomaterials such as 316L stainless steel, titanium-6aluminium-4vanadium (Ti6Al4V) and cobalt-chromium (CoCr) are highlighted. Limitations and future potential of such technologies are also explored. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  17. Anomalous behavior of the magnetic hyperfine field at 140Ce impurities at La sites in LaMnSi2

    Science.gov (United States)

    Domienikan, C.; Bosch-Santos, B.; Cabrera-Pasca, G. A.; Saxena, R. N.; Carbonari, A. W.

    2018-05-01

    Magnetic hyperfine field has been measured in the orthorhombic intermetallic compound LaMnSi2 with perturbed angular correlation (PAC) spectroscopy using radioactive 140La(140Ce) nuclear probes. Magnetization measurements were also carried out in this compound with MPSM-SQUID magnetometer. Samples of LaMnSi2 compound were prepared by arc melting the component metals with high purity under argon atmosphere followed by annealing at 1000°C for 60 h under helium atmosphere and quenching in water. X-ray analysis confirmed the samples to be in a single phase with correct crystal structure expected for LaMnSi2 compound. The radioactive 140La (T1/2 = 40 h) nuclei were produced by direct irradiation of the sample with neutrons in the IEA-R1 nuclear research reactor at IPEN with a flux of ˜ 1013 n cm-2s-1 for about 3 - 4 min. The PAC measurements were carried out with a six BaF2 detector spectrometer at several temperatures between 10 K and 400 K. Temperature dependence of the hyperfine field, Bhf was found to be anomalous. A modified two-state model explained this anomalous behavior where the effective magnetic hyperfine field at 140Ce is believed to have two contributions, one from the unstable localized spins at Ce impurities and another from the magnetic Mn atoms of the host. The competition of these two contributions explains the anomalous behavior observed for the temperature dependence of the magnetic hyperfine field at 140Ce. The ferromagnetic transition temperature (TC) of LaMnSi2 was determined to be 400(1) K confirming the magnetic measurements.

  18. Mechanochemical processing for metals and metal alloys

    Science.gov (United States)

    Froes, Francis H.; Eranezhuth, Baburaj G.; Prisbrey, Keith

    2001-01-01

    A set of processes for preparing metal powders, including metal alloy powders, by ambient temperature reduction of a reducible metal compound by a reactive metal or metal hydride through mechanochemical processing. The reduction process includes milling reactants to induce and complete the reduction reaction. The preferred reducing agents include magnesium and calcium hydride powders. A process of pre-milling magnesium as a reducing agent to increase the activity of the magnesium has been established as one part of the invention.

  19. Metallic glassy Zr70Ni20Pd10 powders for improving the hydrogenation/dehydrogenation behavior of MgH2

    Science.gov (United States)

    El-Eskandarany, M. Sherif

    2016-01-01

    Because of its low density, storage of hydrogen in the gaseous and liquids states possess technical and economic challenges. One practical solution for utilizing hydrogen in vehicles with proton-exchange fuel cells membranes is storing hydrogen in metal hydrides. Magnesium hydride (MgH2) remains the best hydrogen storage material due to its high hydrogen capacity and low cost of production. Due to its high activation energy and poor hydrogen sorption/desorption kinetics at moderate temperatures, the pure form of MgH2 is usually mechanically treated by high-energy ball mills and catalyzed with different types of catalysts. These steps are necessary for destabilizing MgH2 to enhance its kinetics behaviors. In the present work, we used a small mole fractions (5 wt.%) of metallic glassy of Zr70Ni20Pd10 powders as a new enhancement agent to improve its hydrogenation/dehydrogenation behaviors of MgH2. This short-range ordered material led to lower the decomposition temperature of MgH2 and its activation energy by about 121 °C and 51 kJ/mol, respectively. Complete hydrogenation/dehydrogenation processes were successfully achieved to charge/discharge about 6 wt.%H2 at 100 °C/200 °C within 1.18 min/3.8 min, respectively. In addition, this new nanocomposite system shows high performance of achieving continuous 100 hydrogen charging/discharging cycles without degradation. PMID:27220994

  20. The first direct measurement of the hyperfine splitting in positronium

    Energy Technology Data Exchange (ETDEWEB)

    Suehara, T; Ishida, A; Namba, T; Asai, S; Kobayashi, T [Department of Physics and ICEPP, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 33-0033 (Japan); Saitot, H [Institute of Physics, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902 (Japan); Yoshida, M [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki, 305-0801 (Japan); Idehara, T; Ogawa, I; Kobayashi, S [FIR Center, University of Fukui, 3-9-1 Bunkyo, Fukui, 910-8507 (Japan); Sabchevski, S, E-mail: suehara@icepp.s.u-tokyo.ac.j [Bulgarian Academy of Science, 1, 15 Noemvri Str., 1040 Sofia (Bulgaria)

    2009-03-01

    Positronium is an ideal system for the research of the QED. The hyperfine splitting of positronium (Ps-HFS) is sensitive to the new physics beyond the Standard Model via a vacuum oscillation. Previous experimental results of the Ps-HFS show 3.5 {sigma} discrepancy from the QED calculation, and it might be caused by uncertainties of the indirect method with static magnetic field and a few GHz RF. We developed a new direct measurement system of the Ps-HFS without static magnetic field, using a sub-THz gyrotron and a quasi-optical Fabry-Perot cavity. Status (hopefully the first result) of the direct positronium hyperfine transition observation will be presented.

  1. Hyperfine coupling of the hydrogen atom in high temperature water.

    Science.gov (United States)

    Nuzhdin, Kirill; Bartels, David M

    2013-03-28

    The hyperfine coupling constant of the hydrogen atom has been measured in pressurized liquid water up to 300 °C. The reduced constant A(water)∕A(vacuum) is 0.9939 at room temperature, and decreases to a minimum of 0.9918 at 240 °C. The reduced constant then increases at higher temperature. The g-factor is 2.002244(10) at room temperature and decreases to 2.00221(1) at 240 °C. The change in g-factor is proportional to the change in hyperfine coupling. The behavior below 110 °C is in excellent agreement with a previously proposed model in which the H atom is confined to a harmonic solvent cage, and vibrations within the cage mix "p-type" character into the wavefunction, resulting inA(water)∕A(vacuum) molar volume information can recover the observed minima near 240 °C.

  2. Investigation of hyperfine interactions in DNA and antibody of different lineages of mice infected by T. cruzi by perturbed gamma-gamma angular correlation spectroscopy

    International Nuclear Information System (INIS)

    Silva, Andreia dos Santos

    2012-01-01

    In the present work perturbed angular correlation (PAC) spectroscopy was used to measured electric quadrupole interactions in DNA biomolecules of different mice lineages (A/J, C57BL/6, B6AF1, BXA1 e BXA2), samples of different isotypes of immunoglobulin G (IgG1, IgG2a e IgG2b) and active portions of complete and fragmented immunoglobulin responsible by the immune response. Electric quadrupole interactions were also measured in DNA nitrogenous bases (adenine, cytosine, guanine, thymine). PAC measurements were performed using 111 In → 111C d; 111mC d → 111 Cd; 111 Ag → 111 Cd; e 181 Hf → 181 Ta as probe nuclei, and carried out at room temperature and liquid nitrogen temperature, in order to investigate dynamic and static hyperfine interactions, respectively. The biomolecule samples were directly marked with the radioactive parent nuclei, whose atom link to a certain site in the biomolecules. The biological materials as well as the probe nuclei were chosen to investigate the possibility to use PAC spectroscopy to measure hyperfine parameters at nuclei from metallic elements bound to biomolecules (including the use of different probe nuclei produced in the decay of parent nuclei of four different metals) and also to study the behavior of different biomolecules by means of the measured hyperfine parameters. Results show differences in the hyperfine interactions of probe nuclei bound to the studied biomolecules. Such differences were observed by variations in the hyperfine parameters, which depend on the type of biomolecule and the results also show that the probe nuclei atom bound to the molecule in some cases and in others do not. (author)

  3. The hyperfine structure - a message from the inner circle

    International Nuclear Information System (INIS)

    Sturesson, L.

    1992-06-01

    Experiment have been performed to determine the lifetimes and the hyperfine structures of excited states in atoms. Decay curves were recorded with the aid of time-resolved laser spectroscopy. From these curves, it was possible to evaluated the lifetimes with high accuracy. In certain cases, the hyperfine structures were also determined with high accuracy form quantum beat signals. The elements studied were lithium, sodium, copper, iron and silver. In favourable cases, the method of delayed coincidence gave uncertainties in lifetime measurements of about 0.5%. The detection of quantum beat signals with frequencies higher than 1 GHz was demonstrated. The effects of non-white excitation and delayed detection on level-crossing signals were also investigated. The method of delayed detection causes a narrowing of the detected signal, though most of the intensity of the signals is lost and it exhibits an oscillatory behaviour due to the gating procedure. The effect of high-intensity beams in combination with optically dense media applied to saturation absorption spectroscopy has been investigated both theoretically and experimentally. In this regime the signals exhibited sharp profiles, with widths narrower than the natural linewidth, duel to the non-linearity of the medium. Also, a strong rejection of the background was achieved. These features make this regime interesting for frequency stabilization purpose. Using wavefunctions calculated with the multi-configuration Hartree-Fock method, the hyperfine structure interaction constants of the 3s 2 S and the 3p 2 P states in 23 Na and the 3s3p 1.3 P and the 3s3d 1.3 D states in 25 Mg, the only stable isotope of magnesium with a hyperfine structure, were determined. (62 refs.) (au)

  4. Dephasing and hyperfine interaction in carbon nanotubes double quantum dots

    DEFF Research Database (Denmark)

    Reynoso, Andres Alejandro; Flensberg, Karsten

    2012-01-01

    We study theoretically the return probability experiment, which is used to measure the dephasing time T-2*, in a double quantum dot (DQD) in semiconducting carbon nanotubes with spin-orbit coupling and disorder-induced valley mixing. Dephasing is due to hyperfine interaction with the spins of the C...... with these for DQDs in clean nanotubes, whereas the disorder effect is always relevant when the magnetic field is perpendicular to the nanotube axis....

  5. The hyperfine properties of iron-gallium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Elzain, M., E-mail: elzain@squ.edu.om; Gismelseed, A.; Al-Rawas, A.; Yousif, A.; Widatallah, H.; Al-Azri, Maya [Sultan Qaboos University, Department of Physics (Oman); Al-Barwani, M. [NYU Abu Dhabi (United Arab Emirates)

    2016-12-15

    The hyperfine properties at Fe site in iron-gallium alloy are calculated using the full-potential linear-augmented-plane-waves method. We have calculated the Fermi contact field (B{sub hf}) and isomer shift (δ) at the Fe site versus the number of neighbouring Ga atoms. We found that B{sub hf} decrease whereas δ increases with increasing number of neighbouring G atom. In addition we have calculated the hyperfine properties of FeGa system with DO{sub 3} structure, where various distributions of 4 the Ga atoms in the conventional unit cell are considered (including the regular DO{sub 3} structure). We found that the DO{sub 3} structure has the lowest energy as compared to the other configurations. The two distinct A and D sites of the ordered DO{sub 3} conventional unit cell have two distinct values for B{sub hf} and δ. On changing the atomic arrangement of the Ga atoms within the conventional unit cell, the configuration of the A site is maintained whereas that of the D site becomes imperfect. The contact magnetic hyperfine fields of the D-like sites in the imperfect structures are lower than that of the DO{sub 3}D site.

  6. Hyperfine Structure Measurements of Antiprotonic $^3$He using Microwave Spectroscopy

    CERN Document Server

    Friedreich, Susanne

    The goal of this project was to measure the hyperfine structure of $\\overline{\\text{p}}^3$He$^+$ using the technique of laser-microwave-laser spectroscopy. Antiprotonic helium ($\\overline{\\text{p}}$He$^+$) is a neutral exotic atom, consisting of a helium nucleus, an electron and an antiproton. The interactions of the angular momenta of its constituents cause a hyperfine splitting ({HFS}) within the energy states of this new atom. The 3\\% of formed antiprotonic helium atoms which remain in a metastable, radiative decay-dominated state have a lifetime of about 1-3~$\\mu$s. This time window is used to do spectroscopic studies. The hyperfine structure of $\\overline{\\text{p}}^4$He$^+$ was already extensively investigated before. From these measurements the spin magnetic moment of the antiproton can be determined. A comparison of the result to the proton magnetic moment provides a test of {CPT} invariance. Due to its higher complexity the new exotic three-body system of $\\overline{\\text{p}}^3$He$^+$ is a cross-check...

  7. Vibration dependence of the tensor spin-spin and scalar spin-spin hyperfine interactions by precision measurement of hyperfine structures of 127I2 near 532 nm

    International Nuclear Information System (INIS)

    Hong Fenglei; Zhang Yun; Ishikawa, Jun; Onae, Atsushi; Matsumoto, Hirokazu

    2002-01-01

    Hyperfine structures of the R(87)33-0, R(145)37-0, and P(132)36-0 transitions of molecular iodine near 532 nm are measured by observing the heterodyne beat-note signal of two I 2 -stabilized lasers, whose frequencies are bridged by an optical frequency comb generator. The measured hyperfine splittings are fit to a four-term Hamiltonian, which includes the electric quadrupole, spin-rotation, tensor spin-spin, and scalar spin-spin interactions, with an accuracy of ∼720 Hz. High-accurate hyperfine constants are obtained from this fit. Vibration dependences of the tensor spin-spin and scalar spin-spin hyperfine constants are determined for molecular iodine, for the first time to our knowledge. The observed hyperfine transitions are good optical frequency references in the 532-nm region

  8. Obtainment, machining and wear of metal matrix composites processed by powder metallurgy; Obtencao, usinagem e desgaste de materiais compositos de matriz metalica processados via metalurgia do po

    Energy Technology Data Exchange (ETDEWEB)

    Jesus, Edilson Rosa Barbosa de. E-mail: erbjesus@usp.br

    1998-07-01

    The aim of this investigation was the obtainment of metal matrix composites (MMC) by the route of powder metallurgy, and the valuation of these materials with relation to their machining and wear characteristics. Firstly, were obtained pure commercial aluminium matrix composites materials, with 5, 10 and 15% volumetric fraction of silicon carbide particles. Was also obtained a material without reinforcement particles in order to verify by comparison, the influence of addition of reinforcement particles. The obtained materials were characterized physics (hydrostatic density), mechanics (hardness and tensile tests) and microstructurally (optical microscopy and scanning electron microscopy). The results showed a homogeneous distribution of reinforcement particles in the composite, and improvement in the mechanical properties, mainly tensile strength (UTS) in comparison to the unreinforced material. After, tests were made to verify the materials behavior during machining and to check the performance of several tool materials (cemented carbide, ceramics and polycrystalline diamond). In these tests, values of the cutting force were measured by instrumented tool-holders. Phenomena such as tool wear, built-up edge formation and mechanism of chip formation were also observed and evaluated. The results from the cemented carbide tool tests, were utilised for the machinability index determination of each material. These results were applied to the Taylor equation and the equation constants for each material and test conditions were determined. The results showed that the inclusion of silicon carbide particles made extremely difficult the machining of the composites, and only with diamond tool, satisfactory results were obtained. At last, wear tests were performed to verify the influence of the reinforcement particles in the characteristics of wear resistance of the materials. The results obtained were utilized in the wear coefficient determination for each material. The

  9. Radial and zonal modes in hyperfine-scale stellarator turbulence

    Science.gov (United States)

    Jenko, F.; Kendl, A.

    2002-10-01

    Electromagnetic plasma turbulence at hyperfine (i.e., electron gyroradius) scales is studied in the geometry of an advanced stellarator fusion experiment, Wendelstein 7-AS [H. Renner, Plasma Phys. Controlled Fusion 31, 1579 (1989)], by means of nonlinear gyrokinetic simulations. It is demonstrated that high-amplitude radial streamers may also exist in non-tokamak devices, raising the electron heat flux to experimentally relevant values. Moreover, some statistical characteristics of the fully developed turbulence are computed, highlighting the (co-)existence, nature, and role of self-generated zonal flows and fields.

  10. Kinetic models in spin chemistry. 1. The hyperfine interaction

    DEFF Research Database (Denmark)

    Mojaza, M.; Pedersen, J. B.

    2012-01-01

    Kinetic models for quantum systems are quite popular due to their simplicity, although they are difficult to justify. We show that the transformation from quantum to kinetic description can be done exactly for the hyperfine interaction of one nuclei with arbitrary spin; more spins are described...... with a very good approximation. The crucial points are: to represents the quantum coherent oscillations by first order rate constants, and to determine the number of kinetic channels corresponding to a given interaction. We consider a radical pair system with spin selective reactions and calculate the spin...

  11. Hyperfine magnetic fields at 111Cd in Heusler alloys

    International Nuclear Information System (INIS)

    Styczen, B.; Szytula, A.; Walus, W.

    1977-01-01

    The magnitudes and signs of the hyperfine magnetic field on 111 Cd nuclei at Z sites in the ordered ferromagnetic Heusler alloys X 2 MnZ and XMnZ (where X is Cu, Ni, Pd while Z is In, Sn and Sb) have been investigated at liquid nitrogen and room temperatures using TDPAC method. Their signs have been found to be negative. The results have been compared with the predictions of Caroli-Blandin and Campbell-Blandin models and RKKY theory. (author)

  12. Phonons from neutron powder diffraction

    Science.gov (United States)

    Dimitrov, D. A.; Louca, D.; Röder, H.

    1999-09-01

    The spherically averaged structure function S(\\|q\\|) obtained from pulsed neutron powder diffraction contains both elastic and inelastic scattering via an integral over energy. The Fourier transformation of S(\\|q\\|) to real space, as is done in the pair density function (PDF) analysis, regularizes the data, i.e., it accentuates the diffuse scattering. We present a technique which enables the extraction of off-center (\\|q\\|≠0) phonon information from powder diffraction experiments by comparing the experimental PDF with theoretical calculations based on standard interatomic potentials and the crystal symmetry. This procedure [dynamics from powder diffraction] has been successfully implemented as demonstrated here for two systems, a simple metal fcc Ni and an ionic crystal CaF2. Although computationally intensive, this data analysis allows for a phonon based modeling of the PDF, and additionally provides off-center phonon information from neutron powder diffraction.

  13. Some ENDOR studies of 3d transition metal ions in semiconductors

    International Nuclear Information System (INIS)

    Engelen, P.P.J.

    1980-01-01

    The author considers 3d transition metal ions substituted in covalent semiconducting crystals. The magnitude of the contact hyperfine field at the 59 Co nucleus in cobalt doped CdS is determined. The results of an ENDOR study of supertransferred hyperfine interactions with nearest neighbour Ga ions in Mn doped GaP are presented. (G.T.H.)

  14. Hyperfine interactions in the cubic semiconductor CdO

    International Nuclear Information System (INIS)

    Desimoni, J.; Bibiloni, A.G.; Massolo, C.P.; Renteria, M.

    1990-01-01

    The time-differential perturbed angular correlation technique has been applied using 111 In probes, which decay through electron capture to 111 Cd, to study the hyperfine interaction in cubic cadmium oxide, in the temperature range RT--740 degree C (RT denotes room temperature). The main fraction of probes are located in perfect-lattice sites, with null electric field gradient in agreement with crystalline-structure considerations. Around 25% of the total intensity shows an electric-field-gradient distribution around V zz =0. This corresponds to probes located in sites perturbed by the vicinity of oxygen vacancies in the lattice. The temperature-independent behavior of the measured hyperfine parameters is discussed in terms of conductivity and band-structure properties of the semiconductor. No time-dependent interaction arising from nuclear electron-capture aftereffects are seen in this experiment. This is in agreement with a previously reported model of aftereffect processes which states that only holes trapped in impurity levels inside the band gap of the semiconductor can give rise to detectable fluctuating interactions

  15. Hyperfine interactions in the cubic semiconductor CdO

    Energy Technology Data Exchange (ETDEWEB)

    Desimoni, J.; Bibiloni, A.G.; Massolo, C.P.; Renteria, M. (Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Casilla de Correo No. 67, 1900 La Plata, Argentina (AR))

    1990-01-15

    The time-differential perturbed angular correlation technique has been applied using {sup 111}In probes, which decay through electron capture to {sup 111}Cd, to study the hyperfine interaction in cubic cadmium oxide, in the temperature range RT--740 {degree}C (RT denotes room temperature). The main fraction of probes are located in perfect-lattice sites, with null electric field gradient in agreement with crystalline-structure considerations. Around 25% of the total intensity shows an electric-field-gradient distribution around {ital V}{sub {ital zz}}=0. This corresponds to probes located in sites perturbed by the vicinity of oxygen vacancies in the lattice. The temperature-independent behavior of the measured hyperfine parameters is discussed in terms of conductivity and band-structure properties of the semiconductor. No time-dependent interaction arising from nuclear electron-capture aftereffects are seen in this experiment. This is in agreement with a previously reported model of aftereffect processes which states that only holes trapped in impurity levels inside the band gap of the semiconductor can give rise to detectable fluctuating interactions.

  16. Defect Control of the WC Hardmetal by Mixing Recycled WC Nano Powder and Tungsten Powder

    Science.gov (United States)

    Hur, Man Gyu; Shin, Mi Kyung; Kim, Deug Joong; Yoon, Dae Ho

    2018-03-01

    Tungsten metal powder was added to recycled WC nano powder to control the macro and micro defects of WC hardmetal. The macro and micro defects caused by the excess carbon in the recycled WC powder were markedly removed after the addition of tungsten metal powder ranging from 2 to 6 wt%. The density and hardness of the WC hardmetals also increased due to the removal of defects after adding the tungsten metal powder. The density and hardness of WC hardmetals with the addition of W metal powder ranged from 8 to 12 wt% increased linearly as the W metal powder content increased due to the formation of a new (Co- and W-rich WC) composition. The surface morphology of the WC hardmetals was observed via field emission scanning electron microscopy, and a quantitative elemental analysis was conducted via X-ray fluorescence spectrometry and energy dispersive X-ray analysis. The density and hardness of the WC hardmetals were respectively measured using an analytical balance and a Vikers hardness tester. The effect on the defects in the recycled WC hardmetals through the addition of the tungsten metal powder was discussed in detail.

  17. Defect Control of the WC Hardmetal by Mixing Recycled WC Nano Powder and Tungsten Powder

    Science.gov (United States)

    Hur, Man Gyu; Shin, Mi Kyung; Kim, Deug Joong; Yoon, Dae Ho

    2018-02-01

    Tungsten metal powder was added to recycled WC nano powder to control the macro and micro defects of WC hardmetal. The macro and micro defects caused by the excess carbon in the recycled WC powder were markedly removed after the addition of tungsten metal powder ranging from 2 to 6 wt%. The density and hardness of the WC hardmetals also increased due to the removal of defects after adding the tungsten metal powder. The density and hardness of WC hardmetals with the addition of W metal powder ranged from 8 to 12 wt% increased linearly as the W metal powder content increased due to the formation of a new (Co- and W-rich WC) composition. The surface morphology of the WC hardmetals was observed via field emission scanning electron microscopy, and a quantitative elemental analysis was conducted via X-ray fluorescence spectrometry and energy dispersive X-ray analysis. The density and hardness of the WC hardmetals were respectively measured using an analytical balance and a Vikers hardness tester. The effect on the defects in the recycled WC hardmetals through the addition of the tungsten metal powder was discussed in detail.

  18. Comment on contact contributions to the magnetic hyperfine interaction of rare-earth impurities in iron

    International Nuclear Information System (INIS)

    Bernas, H.

    1977-01-01

    The influence of the strong d character of the Fe conduction band on the hyperfine interaction of dilute rare earth impurities is emphasized, and the contact contributions are estimated. Apparent inconsistencies between hyperfine field measurements for Eu and Gd in Fe are noted

  19. Powder Characterization and Optimization for Additive Manufacturing

    OpenAIRE

    Cordova, Laura; Campos, Mónica; Tinga, Tiedo

    2017-01-01

    Achieving the optimal quality for Additive Manufactured (AM) parts does not only depend on setting the right process parameters. Material feedstock also plays an important role when aiming for high performance products. The metal AM processes that are most applicable to industry, Powder Bed Fusion and Directed Energy Deposition, use metal powder as raw material. Therefore, controlling the quality and correctly characterizing the particles used in the process is a key step to successfully appl...

  20. Simple process to fabricate nitride alloy powders

    International Nuclear Information System (INIS)

    Yang, Jae Ho; Kim, Dong-Joo; Kim, Keon Sik; Rhee, Young Woo; Oh, Jang-Soo; Kim, Jong Hun; Koo, Yang Hyun

    2013-01-01

    Uranium mono-nitride (UN) is considered as a fuel material [1] for accident-tolerant fuel to compensate for the loss of fissile fuel material caused by adopting a thickened cladding such as SiC composites. Uranium nitride powders can be fabricated by a carbothermic reduction of the oxide powders, or the nitriding of metal uranium. Among them, a direct nitriding process of metal is more attractive because it has advantages in the mass production of high-purity powders and the reusing of expensive 15 N 2 gas. However, since metal uranium is usually fabricated in the form of bulk ingots, it has a drawback in the fabrication of fine powders. The Korea Atomic Energy Research Institute (KAERI) has a centrifugal atomisation technique to fabricate uranium and uranium alloy powders. In this study, a simple reaction method was tested to fabricate nitride fuel powders directly from uranium metal alloy powders. Spherical powder and flake of uranium metal alloys were fabricated using a centrifugal atomisation method. The nitride powders were obtained by thermal treating the metal particles under nitrogen containing gas. The phase and morphology evolutions of powders were investigated during the nitriding process. A phase analysis of nitride powders was also part of the present work. KAERI has developed the centrifugal rotating disk atomisation process to fabricate spherical uranium metal alloy powders which are used as advanced fuel materials for research reactors. The rotating disk atomisation system involves the tasks of melting, atomising, and collecting. A nozzle in the bottom of melting crucible introduces melt at the center of a spinning disk. The centrifugal force carries the melt to the edge of the disk and throws the melt off the edge. Size and shape of droplets can be controlled by changing the nozzle size, the disk diameter and disk speed independently or simultaneously. By adjusting the processing parameters of the centrifugal atomiser, a spherical and flake shape

  1. Temperature dependence of the magnetic hyperfine field at an s–p impurity diluted in RNi{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, A.L. de, E-mail: alexandre.oliveira@ifrj.edu.br [Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro, Campus Nilópolis, RJ (Brazil); Chaves, C.M., E-mail: cmch@cbpf.br [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro, RJ (Brazil); Oliveira, N.A. de [Instituto de Física Armando Dias Tavares, Universidade do Estado do Rio de Janeiro, Rio de Janeiro (Brazil); Troper, A. [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro, RJ (Brazil)

    2016-03-01

    We study the formation of local magnetic moments and magnetic hyperfine fields at an s–p impurity diluted in intermetallic Laves phase compounds RNi{sub 2} (R=Nd, Sm, Gd, Tb, Dy) at finite temperatures. We start with a clean host and later the impurity is introduced. The host has two-coupled (R and Ni) sublattice Hubbard Hamiltonians but the Ni sublattice can be disregarded because its d band, being full, is magnetically ineffective. Also, the effect of the 4f electrons of R is represented by the polarization they produce on the d band. This leaves us with a lattice of effective rare earth R-ions with polarized electrons. For the dd electronic interaction we use the Hubbard–Stratonovich identity in a functional integral approach in the static saddle point approximation. - Highlights: • Functional integral method in the static limit, producing site disorder, is used. • The site disorder is treated with the Coherent Potential Approximation (CPA). • Non magnetic Ni generates an effective lattice with only a polarized R d band. • The effective R lattice differ from the pure R metal: Results and Discussions. • The experimental curve of hyperfine fields × temperature are very well reproduced.

  2. Hyperfine Structure and Isotope Shifts in Dy II

    Directory of Open Access Journals (Sweden)

    Dylan F. Del Papa

    2017-01-01

    Full Text Available Using fast-ion-beam laser-fluorescence spectroscopy (FIBLAS, we have measured the hyperfine structure (hfs of 14 levels and an additional four transitions in Dy II and the isotope shifts (IS of 12 transitions in the wavelength range of 422–460 nm. These are the first precision measurements of this kind in Dy II. Along with hfs and IS, new undocumented transitions were discovered within 3 GHz of the targeted transitions. These atomic data are essential for astrophysical studies of chemical abundances, allowing correction for saturation and the effects of blended lines. Lanthanide abundances are important in diffusion modeling of stellar interiors, and in the mechanisms and history of nucleosynthesis in the universe. Hfs and IS also play an important role in the classification of energy levels, and provide a benchmark for theoretical atomic structure calculations.

  3. Improved Study of the Antiprotonic Helium Hyperfine Structure

    CERN Document Server

    Pask, T.; Dax, A.; Hayano, R.S.; Hori, M.; Horvath, D.; Juhasz, B.; Malbrunot, C.; Marton, J.; Ono, N.; Suzuki, K.; Zmeskal, J.; Widmann, E.

    2008-01-01

    We report the initial results from a systematic study of the hyperfine (HF) structure of antiprotonic helium (n,l) = (37,~35) carried out at the Antiproton Decelerator (AD) at CERN. We performed a laser-microwave-laser resonance spectroscopy using a continuous wave (cw) pulse-amplified laser system and microwave cavity to measure the HF transition frequencies. Improvements in the spectral linewidth and stability of our laser system have increased the precision of these measurements by a factor of five and reduced the line width by a factor of three compared to our previous results. A comparison of the experimentally measured transition frequencies with three body QED calculations can be used to determine the antiproton spin magnetic moment, leading towards a test of CPT invariance.

  4. Measurement and modeling of hyperfine parameters in ferroic materials

    CERN Document Server

    Gonçalves, João Nuno; Correia, J G

    This thesis presents the results of perturbed angular correlation (PAC) experiments , an experimental technique which measures the hyperfine interaction at probes (radioactive ions implanted in the materials to study), from which one infers local information on an atomic scale. Furthermore, abinitio calculations using density functional theory electronic obtain results that directly complement the experiments, and are also used for theoretical research. These methods were applied in two families of materials. The manganites, with the possible existence of magnetic, charge, orbital and ferroelectric orders, are of fundamental and technological interest. The experimental results are obtained in the alkaline-earth manganites (Ca, Ba, Sr), with special interest due to the structural variety of possible polymorphs. With probes of Cd and In the stability of the probe and its location in a wide temperature range is established and a comparison with calculations allows the physical interpretation of the results. Cal...

  5. Nagaoka’s atomic model and hyperfine interactions

    Science.gov (United States)

    INAMURA, Takashi T.

    2016-01-01

    The prevailing view of Nagaoka’s “Saturnian” atom is so misleading that today many people have an erroneous picture of Nagaoka’s vision. They believe it to be a system involving a ‘giant core’ with electrons circulating just outside. Actually, though, in view of the Coulomb potential related to the atomic nucleus, Nagaoka’s model is exactly the same as Rutherford’s. This is true of the Bohr atom, too. To give proper credit, Nagaoka should be remembered together with Rutherford and Bohr in the history of the atomic model. It is also pointed out that Nagaoka was a pioneer of understanding hyperfine interactions in order to study nuclear structure. PMID:27063182

  6. Muon hyperfine fields in iron and its dilute alloys

    Science.gov (United States)

    Stronach, C. E.; Squire, K. R.; Arrott, A. S.; Patterson, B. D.; Heinrich, B.; Lankford, W. F.; Fiory, A. T.; Kossler, W. J.; Singh, J. J.

    1981-01-01

    The temperature dependence of the interstitial magnetic field, B, as determined by the rotation of the spin of the muon, has been measured for dilute polycrystalline iron alloys with Mo, Ti, and Nb additions over a temperature range of 240 to 633 K. In all cases the behaviors differ from one another and from the Fe(Al) alloys previously studied. B, which is negative with respect to the magnetization, is increased in magnitude by Al and Mo, and decreased greatly by Ti. The addition of Nb creates a two-phase alloy from which the role of heterogeneity and/or strain on B in iron can be assessed. If the temperature dependence of the hyperfine field extracted from B for Fe(Mo) alloys is interpreted on the model previously used to discuss the Fe(Al) data, then the muon must be attracted to the Mo atom while repelled by the Al atoms as the temperature decreases.

  7. A source of antihydrogen for in-flight hyperfine spectroscopy

    CERN Document Server

    Kuroda, N; Murtagh, D J; Van Gorp, S; Nagata, Y; Diermaier, M; Federmann, S; Leali, M; Malbrunot, C; Mascagna, V; Massiczek, O; Michishio, K; Mizutani, T; Mohri, A; Nagahama, H; Ohtsuka, M; Radics, B; Sakurai, S; Sauerzopf, C; Suzuki, K; Tajima, M; Torii, H A; Venturelli, L; Wünschek, B; Zmeskal, J; Zurlo, N; Higaki, H; Kanai, Y; Lodi Rizzini, E; Nagashima, Y; Matsuda, Y; Widmann, E; Yamazaki, Y

    2014-01-01

    Antihydrogen, a positron bound to an antiproton, is the simplest antiatom. Its counterpart—hydrogen—is one of the most precisely investigated and best understood systems in physics research. High-resolution comparisons of both systems provide sensitive tests of CPT symmetry, which is the most fundamental symmetry in the Standard Model of elementary particle physics. Any measured difference would point to CPT violation and thus to new physics. Here we report the development of an antihydrogen source using a cusp trap for in-flight spectroscopy. A total of 80 antihydrogen atoms are unambiguously detected 2.7 m downstream of the production region, where perturbing residual magnetic fields are small. This is a major step towards precision spectroscopy of the ground-state hyperfine splitting of antihydrogen using Rabi-like beam spectroscopy.

  8. Precise frequency measurements of iodine hyperfine transitions at 671 nm.

    Science.gov (United States)

    Huang, Yao-Chin; Chen, Hsuan-Chen; Chen, Shih-En; Shy, Jow-Tsong; Wang, Li-Bang

    2013-03-01

    We report absolute frequency measurements on the a(1), a(10), and a(15) hyperfine components of the R(78) 4-6 line of (127)I(2). An external-cavity diode laser system at 671 nm is frequency-stabilized to the saturated absorption center obtained by modulation transfer spectroscopy in an iodine vapor cell. Its absolute frequency is measured by an optical frequency comb. The effect of pressure shift is investigated to obtain the absolute transition frequency at zero pressure. Our determination of the line centers reaches a precision of better than 40 kHz and will provide useful input for theoretical calculations. This frequency-stabilized laser can be used as a reference laser for the spectroscopy of lithium D lines.

  9. Optical isotope shifts and hyperfine structure in Cd

    International Nuclear Information System (INIS)

    Brimicombe, M.S.W.M.; Stacey, D.N.; Stacey, V.; Huehnermann, H.; Menzel, N.

    1976-01-01

    The spectral lines lambda 226.5, lambda 441.6, lambda 806.7 and lambda 853.3 nm of Cd II and lambda 508.6 nm of Cd I have been studied under high resolution by means of digital recording interferometry. The relative positions of all the stable isotopes of cadmium in all the lines have been deduced from the measurements. The main object of this study was to provide precise data for the simple p-s transitions lambda 226.5, lambda 806.7 and lambda 853.3 nm. Such lines are the most favourable for theoretical interpretations, and the new results are intended to provide a basis for the separation of mass and field effects in measured isotope shifts in cadmium. The hyperfine structure intervals, which are important in the interpretation of isotope shifts, have also been measured for all the levels involved in the five transitions. (author)

  10. The influence of hyperfine structure on some manganese line profiles in the solar spectrum

    Science.gov (United States)

    Vitas, N.; Vince, I.

    Taking into account effects of hyperfine structure, we calculated the synthetic solar spectrum for wavelength intervals around nine neutral manganese lines. To estimate values of hyperfine components we used the Oxford total absorption oscillator strength measurements (Booth et al. 1983). We compared observed profiles (Photometric Atlas of the Solar Spectrum from 300 to 1000 nm (Delbouille et al. 1973)) of selected manganese lines with synthesized profiles in two cases: when hyperfine structure is not and when it is taken into account. By comparing the calculated with observed spectrum, we corrected the total oscillator strengths of all nine selected manganese lines.

  11. Contact hyperfine field of the 4p and 4f series elements (rare-earths)

    International Nuclear Information System (INIS)

    Doi, I.

    1973-01-01

    The Coulomb correlation effect in the description of the contact hyperfine magnetic structure was analysed. The hyperfine magnetic structure was calculated from the spin polarized Hartree-Fock formalism, using the free electron gas approximation to the exchange-correlation energy of the 4p series atoms and some atoms and ions of the 4f series. No one of the analysed approximations to the exchange-correlation energy describes satisfactorily the contact hyperfine magnetic structure of the 4p and 4f series elements, which were studied [pt

  12. Unravelling the local structure of topological crystalline insulators using hyperfine interactions

    CERN Multimedia

    Phenomena emerging from relativistic electrons in solids have become one the main topical subjects in condensed matter physics. Among a wealth of intriguing new phenomena, several classes of materials have emerged including graphene, topological insulators and Dirac semi-metals. This project is devoted to one such class of materials, in which a subtle distortion of the crystalline lattice drives a material through different topological phases: Z$_{2}$ topological insulator (Z$_{2}$-TI), topological crystalline insulator (TCI), or ferroelectric Rashba semiconductor (FERS). We propose to investigate the local structure of Pb$_{1-x}$Sn$_{x}$Te and Ge$_{1-x}$Sn$_{x}$Te (with $\\textit{x}$ from 0 to 1) using a combination of experimental techniques based on hyperfine interactions: emission Mössbauer spectroscopy (eMS) and perturbed angular correlation spectroscopy (PAC). In particular, we propose to study the effect of composition ($\\textit{x}$ in Pb$_{1-x}$Sn$_{x}$Te and Ge$_{1-x}$Sn$_{x}$Te) on: \\\\ \\\\(1) the mag...

  13. Graft polymerization of acrylic acid and methacrylic acid onto poly(vinylidene fluoride) powder in presence of metallic salt and sulfuric acid

    International Nuclear Information System (INIS)

    Deng Bo; Yu Yang; Zhang Bowu; Yang Xuanxuan; Li Linfan; Yu Ming; Li Jingye

    2011-01-01

    Poly(vinylidene fluoride) (PVDF) powder was grafted with acrylic acid (AAc) or methacrylic acid (MAA) by the pre-irradiation induced graft polymerization technique. The presence of graft chains was proven by FT-IR spectroscopy. The degree of grafting (DG) was calculated by the acid-base back titration method. The synergistic effect of acid and Mohr's salt on the grafting kinetics was examined. The results indicated that adding sulfuric acid and Mohr's salt simultaneously in AAc or MAA solutions led to a strong enhancement in the degree of grafting. The grafted PVDF powder was cast into microfiltration (MF) membranes using the phase inversion method and some properties of the obtained MF membranes were characterized.

  14. Heavy metal content and element analysis of infant formula and milk powder samples purchased on the Tanzanian market: International branded versus black market products.

    Science.gov (United States)

    Sager, M; McCulloch, C R; Schoder, D

    2018-07-30

    Milk powder is a food for malnourished African children and for healthy infants of women with HIV/AIDS. High demand and low purchasing power has resulted in a huge informal, black market in Sub-Saharan Africa. Forty-three milk powder batches were analyzed for 43 chemical elements using ICP-MS One sample (2.3%) was contaminated at a lead concentration of 240 µg/kg dry weight exceeding the European threshold (130 µg/kg dry weight). Macroelement contents revealed a trend decreasing in concentration through skimmed, full cream products to infant formulae. Concentration ranges by dry weight differed in respect of uncertainty intervals of  ±10%. Median Ca, K and P concentrations declined from 11.14 g/kg to 3.21 g/kg, 14.11 g/kg to 4.95 g/kg and 9.12 g/kg to 2.75 g/kg dry mass, respectively. Milk powder samples obtained from the Tanzanian black market were comparable in respect of nutritional and chemical content to international branded full cream products. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Zero-point vibrational corrections to isotropic hyperfine coupling constants in polyatomic molecules.

    Science.gov (United States)

    Chen, Xing; Rinkevicius, Zilvinas; Cao, Zexing; Ruud, Kenneth; Agren, Hans

    2011-01-14

    The present work addresses isotropic hyperfine coupling constants in polyatomic systems with a particular emphasis on a largely neglected, but a posteriori significant, effect, namely zero-point vibrational corrections. Using the density functional restricted-unrestricted approach, the zero-point vibrational corrections are evaluated for the allyl radical and four of its derivatives. In addition for establishing the numerical size of the zero-point vibrational corrections to the isotropic hyperfine coupling constants, we present simple guidelines useful for identifying hydrogens for which such corrections are significant. Based on our findings, we critically re-examine the computational procedures used for the determination of hyperfine coupling constants in general as well as the practice of using experimental hyperfine coupling constants as reference data when benchmarking and optimizing exchange-correlation functionals and basis sets for such calculations.

  16. Suppression of hyperfine dephasing by spatial exchange of double quantum dots

    Science.gov (United States)

    Drummond, David; Pryadko, Leonid P.; Shtengel, Kirill

    2012-12-01

    We examine the logical qubit system of a pair of electron spins in double quantum dots. Each electron experiences a different hyperfine interaction with the local nuclei of the lattice, leading to a relative phase difference, and thus decoherence. Methods such as nuclei polarization, state narrowing, and spin-echo pulses have been proposed to delay decoherence. Instead we propose to suppress hyperfine dephasing by the adiabatic rotation of the dots in real space, leading to the same average hyperfine interaction. We show that the additional effects due to the motion in the presence of spin-orbit coupling are still smaller than the hyperfine interaction, and result in an infidelity below 10-4 after ten decoupling cycles. We discuss a possible experimental setup and physical constraints for this proposal.

  17. Hyperfine interactions and structures of ferrous hydroxide and green rust II in sulfated aqueous media

    International Nuclear Information System (INIS)

    Olowe, A.A.; Genin, J.M.R.; Bauer, P.

    1988-01-01

    A sulfated ferrous hydroxide is obtained by mixing NaOH with melanterite depending on the R = [SO 4 -- ]/[OH - ] ratio and leading by oxidation to the green rust II transient compound. Hyperfine parameters are presented. (orig.)

  18. Faddeev calculations of pμ+p collisions: Effect of hyperfine splitting on the cross sections

    International Nuclear Information System (INIS)

    Hu, Chi-Yu; Kvitsinsky, A.

    1995-01-01

    The Faddeev equations, modified to remove long-range coupling between different channels, are solved in the total-angular-momentum representation for pμ + p collisions. S-wave elastic and hyperfine-transition cross sections are calculated with and without explicit inclusion of the hyperfine splitting ΔE. For hyperfine quenching the simpler approach without hyperfine splitting is found adequate at collision energies above about ΔE, but for elastic scattering it becomes adequate at somewhat higher energies. The present cross sections tend to fall in between earlier calculations done using a large Standard adiabatic expansion and those done using a two-state improved adiabatic expansion, but are closer to the former

  19. Resolved Hyperfine Structure in the Spectra of Crystals for Optical Quantum Memory

    Directory of Open Access Journals (Sweden)

    Popova M.N.

    2015-01-01

    Full Text Available A brief review is given on recent studies of the hyperfine structure and inhomogeneously broadened line profiles in the spectra of rare earth containing crystals considered as promising candidates for optical quantum memory.

  20. Anomalies in resonant absorption line profiles of atoms with large hyperfine splitting

    International Nuclear Information System (INIS)

    Parkhomenko, A.I.; Pod'yachev, S.P.; Privalov, T.I.; Shalagin, A.M.

    1997-01-01

    We examine a monochromatic absorption line in the velocity-nonselective excitation of atoms when the components of the hyperfine stricture of the electronic ground states are optically pumped. We show that the absorption lines possess unusual substructures for some values of the hyperfine splitting of the ground state (which exceed the Doppler absorption linewidth severalfold). These substructures in the absorption spectrum are most apparent if the hyperfine structure of the excited electronic state is taken into account. We calculate the absorption spectra of monochromatic light near the D 1 and D 2 lines of atomic rubidium 85,87 Rb. With real hyperfine splitting taken into account, the D 1 and D 2 lines are modeled by 4- and 6-level diagrams, respectively. Finally, we show that atomic rubidium vapor can be successfully used to observe the spectral features experimentally

  1. Resin-Powder Dispenser

    Science.gov (United States)

    Standfield, Clarence E.

    1994-01-01

    Resin-powder dispenser used at NASA's Langley Research Center for processing of composite-material prepregs. Dispenser evenly distributes powder (resin polymer and other matrix materials in powder form) onto wet uncured prepregs. Provides versatility in distribution of solid resin in prepreg operation. Used wherever there is requirement for even, continuous distribution of small amount of powder.

  2. Investigation of hyperfine parameters of semiconductor oxides SnO2 and TiO2 pure and doped with 3d transition methods using spectroscopy of perturbed gamma-gamma angular correlation

    International Nuclear Information System (INIS)

    Schell, Juliana

    2015-01-01

    This study aimed the use of nuclear technique Perturbed γ-γ Angular Correlation Spectroscopy (PAC) to measure the hyperfine interactions in thin films and powder samples of SnO 2 and TiO 2 pure and doped with transition metals to obtain a systematic investigation of defects and magnetism from an atomic point of view with the main motivation the application in spintronics. The work also focused on the preparation and characterization of samples by conventional techniques such as X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and magnetization measurements. Pure samples of the films were measured by the systematic variation of thermal treatment and applied magnetic field. These measurements were performed in HISKP at the University of Bonn (Rheinische Friedrich-Wilhelms-Universität Bonn) using 111 In( 111 Cd) or 181 Hf ( 181 Ta); at IPEN, in turn, these measurements were performed after the diffusion of the same probe nuclei. Another part of PAC measurements were carried out using 111 mCd( 111 Cd) and 117 Cd ( 117 In) in Isotope Mass Separator On-Line (ISOLDE) at Centre Européen Recherche Nucléaire (CERN). The measurements were performed from 8 K to 1173 K. After comparing results from macroscopic techniques with those from PAC, it was concluded that there is a correlation between the defects, magnetism and the mobility of charge carriers in semiconductors studied here. A step forward in the search for semiconductors, whose magnetic ordering allows its use in electronics based on spin. Some results have been published, including results obtained at the University of Bonn for the sandwich doctorate period [1-7]. (author)

  3. Hyperfine Fields on Actinide Impurities in Ferromagnetic Fe and Ni Hosts

    International Nuclear Information System (INIS)

    Oliveira, A.L. de; Oliveira, N.A. de; Troper, A.

    2003-01-01

    We discuss the local magnetic moments and magnetic hyperfine fields on actinide impurities diluted in Fe and Ni hosts. One adopts a Anderson- Moriya model in which a localized 5f level is hybridized with a spin polarized and charge perturbed d-conduction band. Our self-consistent numerical calculations for the hyperfine fields on the impurity sites are in good agreement with the available experimental data. (author)

  4. Energy Levels, wavelengths and hyperfine structure measurements of Sc II

    Science.gov (United States)

    Hala, Fnu; Nave, Gillian

    2018-01-01

    Lines of singly ionized Scandium (Sc II) along with other Iron group elements have been observed [1] in the region surrounding the massive star Eta Carinae [2,3] called the strontium filament (SrF). The last extensive analysis of Sc II was the four-decade old work of Johansson & Litzen [4], using low-resolution grating spectroscopy. To update and extend the Sc II spectra, we have made observation of Sc/Ar, Sc/Ne and Sc/Ge/Ar hollow cathode emission spectrum on the NIST high resolution FT700 UV/Vis and 2 m UV/Vis/IR Fourier transform spectrometers (FTS). More than 850 Sc II lines have been measured in the wavelength range of 187 nm to 3.2 μm. connecting a total of 152 energy levels. The present work also focuses to resolve hyperfine structure (HFS) in Sc II lines. We aim to obtain accurate transition wavelengths, improved energy levels and HFS constants of Sc II. The latest results from work in progress will be presented.Reference[1] Hartman H, Gull T, Johansson S and Smith N 2004 Astron. Astrophys. 419 215[2] Smith N, Morse J A and Gull T R 2004 Astrophys. J. 605 405[3] Davidson K and Humphreys R M 1997 Annu. Rev. Astron. Astrophys. 35[4] Johansson S and Litzén U 1980 Phys. Scr. 22 49

  5. Recoil effects in the hyperfine structure of QED bound states

    International Nuclear Information System (INIS)

    Bodwin, G.T.; Yennie, D.R.; Gregorio, M.A.

    1985-01-01

    The authors give a general discussion of the derivation from field theory of a formalism for the perturbative solution of the relativistic two-body problem. The lowest-order expression for the four-point function is given in terms of a two-particle three-dimensional propagator in a static potential. It is obtained by fixing the loop energy in the four-dimensional formalism at a point which is independent of the loop momentum and is symmetric in the two particle variables. This method avoids awkward positive- and negative-energy projectors, with their attendant energy square roots, and allows one to recover the Dirac equation straightforwardly in the nonrecoil limit. The perturbations appear as a variety of four-dimensional kernels which are rearranged and regrouped into convenient sets. In particular, they are transformed from the Coulomb to the Feynman gauge, which greatly simplifies the expressions that must be evaluated. Although the approach is particularly convenient for the precision analysis of QED bound states, it is not limited to such applications. The authors use it to give the first unified treatment of all presently known recoil corrections to the muonium hyperfine structure and also to verify the corresponding contributions through order α 2 lnαE/sub F/ in positronium. The required integrals are evaluated analytically

  6. Hyperfine interaction measurements in biological compounds: the case of hydroxyapatite

    International Nuclear Information System (INIS)

    Leite Neto, Osmar Flavio da Silveira

    2014-01-01

    The use o nanoparticles in current medicine are under intense investigation. The possible advantages proposed by these systems are very impressive and the results may be quite schemer. In this scenario, the association of nanoparticles with radioactive materials (radionuclide) may be the most important step since the discovery of radioactive for nuclear medicine and radiopharmacy, especially for cancer targeting and therapy. The hyperfine interaction of the nuclear probe 111 Cd in the Hydroxyapatite compounds has been investigated by perturbed angular correlation (PAC) spectroscopy in room temperature for the hydroxyapatite made in the temperatures of 90°C, 35°C and with Ho doped, both thermalized and not. The thermalized samples were heated to T= 1273 K for 6 h. The 111 Cd was broadcast in the structure of the material by diffusion, closing in quartz tubes were heated – together with the radioactive PAC probe 111 In/ 111 Cd to T = 1073 K for 12 h. In not thermalized samples the PAC spectra indicate a distribution of frequency, but in the thermalized samples, the PAC spectra shows the presence of β-tri calcium phosphate in the structure of this kind of Hydroxyapatite. (author)

  7. Hyperfine anomalies of HCN in cold dark clouds

    International Nuclear Information System (INIS)

    Walmsley, C.M.; Churchwell, E.; Nash, A.; Fitzpatrick, E.; and Physics Department, University of Illinois at Urbana-Champaign)

    1982-01-01

    We report observations of the J = 1→0 line of HCN measured toward six positions in nearby low-temperature dark clouds. The measured relative intensities of the hyperfine components of the J = 1→0 line are anomalous in that the F = 0→1 transition is stronger than would be expected if all three components (F = 2→1, F = 1→1, F = 0→1) had equal excitation temperatures. Differences of approximately 20% in the populations per sublevel of J = 1 could account for the observations. The results are in contrast to the situation observed in warmer molecular clouds associated with H II regions where the F = 1→1 line is anomalously weak. The apparent overpopulation of J = 1, F = 0 in dark clouds may be related to the phenomenon observed in the J = 1→0 transitions of HCO + and HNC in the same objects where 13 C substituted version of these species is found to be stronger than the 12 C species

  8. ISOTROPIC INELASTIC COLLISIONS IN A MULTITERM ATOM WITH HYPERFINE STRUCTURE

    Energy Technology Data Exchange (ETDEWEB)

    Belluzzi, Luca [Istituto Ricerche Solari Locarno, CH-6605 Locarno Monti (Switzerland); Landi Degl’Innocenti, Egidio [Dipartimento di Fisica e Astronomia, Università di Firenze, I-50125 Firenze (Italy); Bueno, Javier Trujillo [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain)

    2015-10-10

    A correct modeling of the scattering polarization profiles observed in some spectral lines of diagnostic interest, the sodium doublet being one of the most important examples, requires taking hyperfine structure (HFS) and quantum interference between different J-levels into account. An atomic model suitable for taking these physical ingredients into account is the so-called multiterm atom with HFS. In this work, we introduce and study the transfer and relaxation rates due to isotropic inelastic collisions with electrons, which enter the statistical equilibrium equations (SEE) for the atomic density matrix of this atomic model. Under the hypothesis that the electron–atom interaction is described by a dipolar operator, we provide useful relations between the rates describing the transfer and relaxation of quantum interference between different levels (whose numerical values are in most cases unknown) and the usual rates for the atomic level populations, for which experimental data and/or approximate theoretical expressions are generally available. For the particular case of a two-term atom with HFS, we present an analytical solution of the SEE for the spherical statistical tensors of the upper term, including both radiative and collisional processes, and we derive the expression of the emission coefficient in the four Stokes parameters. Finally, an illustrative application to the Na i D{sub 1} and D{sub 2} lines is presented.

  9. Metallic powder-bed based 3D printing of cellular scaffolds for orthopaedic implants: A state-of-the-art review on manufacturing, topological design, mechanical properties and biocompatibility.

    Science.gov (United States)

    Tan, X P; Tan, Y J; Chow, C S L; Tor, S B; Yeong, W Y

    2017-07-01

    Metallic cellular scaffold is one of the best choices for orthopaedic implants as a replacement of human body parts, which could improve life quality and increase longevity for the people needed. Unlike conventional methods of making cellular scaffolds, three-dimensional (3D) printing or additive manufacturing opens up new possibilities to fabricate those customisable intricate designs with highly interconnected pores. In the past decade, metallic powder-bed based 3D printing methods emerged and the techniques are becoming increasingly mature recently, where selective laser melting (SLM) and selective electron beam melting (SEBM) are the two representatives. Due to the advantages of good dimensional accuracy, high build resolution, clean build environment, saving materials, high customisability, etc., SLM and SEBM show huge potential in direct customisable manufacturing of metallic cellular scaffolds for orthopaedic implants. Ti-6Al-4V to date is still considered to be the optimal materials for producing orthopaedic implants due to its best combination of biocompatibility, corrosion resistance and mechanical properties. This paper presents a state-of-the-art overview mainly on manufacturing, topological design, mechanical properties and biocompatibility of cellular Ti-6Al-4V scaffolds via SLM and SEBM methods. Current manufacturing limitations, topological shortcomings, uncertainty of biocompatible test were sufficiently discussed herein. Future perspectives and recommendations were given at the end. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Effect of scanning speed and powder flow rate on the evolving properties of laser metal deposited Ti-6Al-4V/Cu composites

    CSIR Research Space (South Africa)

    Erinosho, MF

    2016-01-01

    Full Text Available In laser metal deposition (LMD), good bonding between two similar or dissimilar materials can be achieved if the interrelationships between the processing parameters are well understood. LMD was conducted by varying the scanning speed and keeping...

  11. Powder metallurgy in aerospace research: A survey

    Science.gov (United States)

    Blakeslee, H. W.

    1971-01-01

    The various techniques by which powders can be produced, as pure metals or as alloys, are discussed; the methods by which these powders can be formed into the final parts are explained as well as further processing that may be necessary to meet specific requirements. The NASA developments are detailed, and references are provided for those who wish to obtain further information characteristic of any methodology.

  12. Powder densification maps in Selective Laser Sintering

    International Nuclear Information System (INIS)

    Bourell, D.; Wohlert, M.; Harlan, N.; Beaman, J.; Das, S.

    2002-01-01

    Selective Laser Sintering (SLS) is a manufacturing process in which a part is produced without the need for part-specific tooling. It competes effectively with other manufacturing processes when part geometry is complex and the production run is not large. Traditionally, this was limited to prototype production, although tooling applications are now appearing. This paper describes several applications of powder densification maps to advance solutions in direct SLS of metallic and ceramic powders. Time-dependent plasticity issues arise in pre-processing of powder to make it suitable for SLS and in post-processing of SLS parts to obtain desired density. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  13. Hyperfine interactions studies in perovskite oxides of the type LaMO3 (M = Fe, Cr, Mn and Co)

    International Nuclear Information System (INIS)

    Junqueira, Astrogildo de Carvalho

    2004-01-01

    ABO 3 -type perovskite oxides have ideal cubic structure and usually show distortions to the orthorhombic or rombohedric symmetry. The A and B siteshave 12-fold and 6-fold oxygen coordination, respectively. Distortions of thecubic structure give rise to new electric, structural and magnetic propertieswhich have great technological and scientific interests. Magnetic dipole and electric quadrupole hyperfine interaction measurements were obtained using 111 In -> 111 Cd , 181 Hf -> 181 Ta e 140 La -> 140 Ceradioactive nuclei substituting for the A or B sites via Perturbed Angulargamma-gamma Correlation technique (1-4) . LaMO 3 (M = Fe, Cr, Mn and Co)samples were prepared through the chemical route known as Sol-Gel techniqueand analyzed with x-ray diffraction. Both 111 In and 181 Hf nuclei wereintroduced in to the sample during the chemical procedure and the 140 Lawas obtained by irradiating with neutrons in the IPEN reactor the natural Lapresent in the samples. One of the aims of this work was the analysis of theElectric Field Gradient (EFG) in the A and B sites as function oftemperature, crystal structure or the electronic characteristic of thetransition metal in the B site. The temperature range of the measurements wasabout from 4 K to 1400 K. The experimental EFG showed to be dependent of thesite occupation and the nuclear probe used in the measurements. Spintransition phenomena were also observed in LaCoO 3 samples, which confirmed amodel used to interpret the spin properties in such compound.Crystallographic phase transition effects on the hyperfine parameters inperovskites where M = Fe, Cr and K4n were also analyzed. An additional aim ofthis work was to carry out measurements in the antiferromagnetic region ofthe systems with M = Fe, Cr and Mn using the three radioactive nuclei. Theresults for the magnetic interaction measurements showed a strong influenceof the substitutional sites in the supertransferred magnetic hyperfine fieldfor all the three probe nuclei

  14. Low-Flow-Rate Dry-Powder Feeder

    Science.gov (United States)

    Ramsey, Keith E.

    1994-01-01

    Apparatus feeds small, precise flow of dry powder through laser beam of optical analyzer, measuring patterns of light created by forward scattering (Fraunhofer diffraction) of laser beam from powder particles. From measurement, statistical distribution of sizes of powder particles computed. Developed for analyzing particle-size distributions of solid-propellant powders. Also adapted to use in pharmaceutical industry, in manufacture of metal powder, and in other applications in which particle-size distributions of materials used to control rates of chemical reactions and/or physical characteristics of processes.

  15. Hydrothermal Synthesis and Characterization of a Metal-Organic Framework by Thermogravimetric Analysis, Powder X-Ray Diffraction, and Infrared Spectroscopy: An Integrative Inorganic Chemistry Experiment

    Science.gov (United States)

    Crane, Johanna L.; Anderson, Kelly E.; Conway, Samantha G.

    2015-01-01

    This advanced undergraduate laboratory experiment involves the synthesis and characterization of a metal-organic framework with microporous channels that are held intact via hydrogen bonding of the coordinated water molecules. The hydrothermal synthesis of Co[subscript 3](BTC)[subscript 2]·12H[subscript 2]O (BTC = 1,3,5-benzene tricarboxylic acid)…

  16. Aluminum powder metallurgy processing

    Energy Technology Data Exchange (ETDEWEB)

    Flumerfelt, J.F.

    1999-02-12

    The objective of this dissertation is to explore the hypothesis that there is a strong linkage between gas atomization processing conditions, as-atomized aluminum powder characteristics, and the consolidation methodology required to make components from aluminum powder. The hypothesis was tested with pure aluminum powders produced by commercial air atomization, commercial inert gas atomization, and gas atomization reaction synthesis (GARS). A comparison of the GARS aluminum powders with the commercial aluminum powders showed the former to exhibit superior powder characteristics. The powders were compared in terms of size and shape, bulk chemistry, surface oxide chemistry and structure, and oxide film thickness. Minimum explosive concentration measurements assessed the dependence of explosibility hazard on surface area, oxide film thickness, and gas atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization oxidation of aluminum powder. An Al-Ti-Y GARS alloy exposed in ambient air at different temperatures revealed the effect of reactive alloy elements on post-atomization powder oxidation. The pure aluminum powders were consolidated by two different routes, a conventional consolidation process for fabricating aerospace components with aluminum powder and a proposed alternative. The consolidation procedures were compared by evaluating the consolidated microstructures and the corresponding mechanical properties. A low temperature solid state sintering experiment demonstrated that tap densified GARS aluminum powders can form sintering necks between contacting powder particles, unlike the total resistance to sintering of commercial air atomization aluminum powder.

  17. Excited-level lifetimes and hyperfine-structure measurements on ions using collinear laser--ion-beam spectroscopy

    International Nuclear Information System (INIS)

    Jin, J.; Church, D.A.

    1994-01-01

    The mean lifetimes τ of the Ca II 4p 2 P 1/2 and 4p 2 P 3/2 levels, and the 35 Cl II 4p' 1 F 3 level, have been measured by a variant of the collinear laser--ion-beam lifetime technique applied previously to the Ar II 4p' 2 F 7/2 o level [Jian Jin and D. A. Church, Phys. Rev. A 47, 132 (1993)]. The present results are τ(Ca II, 4p 2 P 1/2 )=7.098(0.020) ns, τ(Ca II, 4p 2 P 3/2 )=6.924(0.019) ns, and τ(Cl II, 4p' 1 F 3 ) =11.17(0.06) ns. The experimental lifetimes of these, plus the Ar II 4p' 2 F 7/2 level, are compared with available recent many-electron calculations. Typically 1%--3% differences between measurement and ab initio theory are found, while certain semiempirical calculations are in better agreement with experiment. Data for other precise lifetime measurements on alkali-metal systems are compared with recent ab initio and semiempirical calculations to provide perspective on the Ca II results. The hyperfine structure of the 35 Cl II 3d' 1 G 4 --4p' 1 F 3 transition was also measured and analyzed in the course of the measurements, with the resulting hyperfine-structure constants: A( 1 F 3 )=301.9(0.5) MHz, B( 1 F 3 )=-6.7(0.8) MHz, A( 1 G 4 )=205.1(0.5) MHz, and B( 1 G 4 )=-3.9(2.4) MHz

  18. Density Functional Restricted-Unrestricted/Molecular Mechanics Theory for Hyperfine Coupling Constants of Molecules in Solution.

    Science.gov (United States)

    Rinkevicius, Zilvinas; Murugan, N Arul; Kongsted, Jacob; Frecuş, Bogdan; Steindal, Arnfinn Hykkerud; Ågren, Hans

    2011-10-11

    A density functional restricted-unrestricted approach, capable of evaluating hyperfine coupling constants with the inclusion of spin polarization effects in a spin-restricted Kohn-Sham method, has been extended to incorporate environmental effects. This is accomplished by means of a hybrid quantum mechanics/molecular mechanics formalism which allows for a granular representation of the polarization and electrostatic interactions with the classically described medium. By this technique, it is possible to trace the physical origin of hyperfine coupling constants in terms of spin polarization and spin density contributions and disentangle the dependence of these contributions on molecular geometry and solvent environment, something that increases the prospects for optimal design of spin labels for particular applications. A demonstration is given for the nitrogen isotropic hyperfine coupling constant in di-tert-butyl nitroxide solvated in water. The results indicate that the direct spin density contribution is about 5 times smaller than the spin polarization contribution to the nitrogen isotropic hyperfine coupling constant and that the latter contribution is solely responsible for the solvent shift of the constant. The developed approach is found capable of achieving satisfactory accuracy in prediction of the hyperfine coupling constants of solvated di-tert-butyl nitroxide and other similar nitroxides without the inclusion of solvent molecules in the quantum region provided polarizable force fields are used for the description of these molecules.

  19. Hyperfine Interaction Studies on Y, Zr, Nb, Mo, Rh, In and Xe in Co

    International Nuclear Information System (INIS)

    Seewald, G.; Zech, E.; Ratai, H.; Schmid, R.; Stadler, R.; Schramm, O.; Koenig, C.; Hinfurtner, B.; Hagn, E.; Deicher, M.; Eder, R.; Forkel-Wirth, D.

    2004-01-01

    Nuclear magnetic resonance on oriented nuclei and modulated adiabatic fast passage on oriented nuclei measurements were performed on several 4d and 5sp impurities in polycrystalline Co(fcc) foils and Co(hcp) single crystals. The hyperfine fields of Y and Zr in Co(fcc), the hyperfine fields of Y, Zr, Nb, Mo, Rh, In and Xe in Co(hcp), the electric field gradients of Zr, Nb and In in Co(hcp), and the nuclear spin-lattice relaxations of Zr, Nb, Rh and In in Co(hcp) were determined. The dependence of the hyperfine fields and electric field gradients in Co(hcp) on the angle between the magnetization and the c axis was investigated in most cases. The magnetic-field dependence of the spin-lattice relaxation was studied for Nb, Rh and In in Co(hcp), applying the magnetic field perpendicular to the c axis. The known hyperfine interaction parameters of the4d and 5sp impurities in Co(fcc) and Co(hcp) are summarized. The new results provide a more detailed picture of the hyperfine interaction in Co.

  20. Powder Metallurgy Reconditioning of Food and Processing Equipment Components

    Science.gov (United States)

    Nafikov, M. Z.; Aipov, R. S.; Konnov, A. Yu.

    2017-12-01

    A powder metallurgy method is developed to recondition the worn surfaces of food and processing equipment components. A combined additive is composed to minimize the powder losses in sintering. A technique is constructed to determine the powder consumption as a function of the required metallic coating thickness. A rapid method is developed to determine the porosity of the coating. The proposed technology is used to fabricate a wear-resistant defectless metallic coating with favorable residual stresses, and the adhesive strength of this coating is equal to the strength of the base metal.

  1. Measurement of the ground-state hyperfine splitting of antihydrogen

    International Nuclear Information System (INIS)

    Juhasz, B.; Widmann, E.

    2006-01-01

    Full text: The hydrogen atom is one of the most extensively studied atomic systems, and its ground state hyperfine splitting (GS-HFS) of ν HFS = 1.42 GHz has been measured with an extremely high precision of δν HFS /ν HFS ∼ 10 -12 . Therefore, the antimatter counterpart of hydrogen, the antihydrogen atom, consisting of an antiproton and a positron, is an ideal laboratory for studying the CPT symmetry. As a test of the CPT invariance, measuring ν HFS of antihydrogen can surpass in accuracy a measurement of the 1S-2S transition frequency proposed by other groups. In fact, it has several advantages over a 1S-2S measurement. Firstly, it does not require the (neutral) antihydrogen atoms to be trapped. Secondly, the only existing consistent extension of the standard model, which is based on a microscopic theory of CPT and Lorentz violation, predicts that νHFS should be more sensitive to CPT violations. In addition, the parameters introduced by Kostelecky et al. have the dimension of energy (or frequency). Therefore, by measuring a relatively small quantity on an energy scale (like the 1.42 GHz GS-HFS splitting), a smaller relative accuracy is needed to reach the same absolute precision for a CPT test. This makes a determination of νHFS with a relative accuracy of 10 -4 competitive to the measured relative mass difference of K 0 and -- K 0 of 10 -18 , which is often quoted as the most precise CPT test so far. The ASACUSA collaboration at CERN's Antiproton Decelerator (AD) has recently submitted a proposal to measure νHFS of antihydrogen in an atomic beam apparatus similar to the ones which were used in the early days of hydrogen HFS spectroscopy. The apparatus consists of two sextupole magnets for the selection and analysis of the spin of the antihydrogen atoms, and a microwave cavity to flip the spin. This method has the advantage that antihydrogen atoms of temperatures up to 150 K, 'evaporating' from a formation region, can be used. Numerical simulations show

  2. Effect of vanadium neighbors on the hyperfine properties of iron-vanadium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Elzain, M., E-mail: elzain@squ.edu.om; Yousif, A.; Gismelseed, A.; Al Rawas, A.; Widatallah, H.; Bouziane, K.; Al-Omari, I. [College of Science, Sultan Qaboos University, Physics Department (Oman)

    2008-06-15

    The electronic and magnetic structures of Fe-V alloys are calculated using the discrete-variational and full-potential linearized-augmented-plane wave methods. The derived hyperfine properties at Fe sites are studied against the number of Fe atoms in the neighbouring shells. As expected the magnetic hyperfine field depends strongly on the number of Fe atoms in the first and second shells of neighbours while its dependence on the variation of atoms in the third shell is weak. The calculated distribution of the magnetic hyperfine fields at the Fe sites, are compared to the experimental data of Krause et al. (Phys Rev B 61:6196-6204, 2000). The contact charge densities and the magnetic moments are also calculated. It was found that the contact charge density increases with increasing V contents and this leads to negative isomer shift on addition of V.

  3. Ab initio calculations of torsionally mediated hyperfine splittings in E states of acetaldehyde

    Science.gov (United States)

    Xu, Li-Hong; Reid, E. M.; Guislain, B.; Hougen, J. T.; Alekseev, E. A.; Krapivin, I.

    2017-12-01

    Quantum chemistry packages can be used to predict with reasonable accuracy spin-rotation hyperfine interaction constants for methanol, which contains one methyl-top internal rotor. In this work we use one of these packages to calculate components of the spin-rotation interaction tensor for acetaldehyde. We then use torsion-rotation wavefunctions obtained from a fit to the acetaldehyde torsion-rotation spectrum to calculate the expected magnitude of hyperfine splittings analogous to those observed at relatively high J values in the E symmetry states of methanol. We find that theory does indeed predict doublet splittings at moderate J values in the acetaldehyde torsion-rotation spectrum, which closely resemble those seen in methanol, but that the factor of three decrease in hyperfine spin-rotation constants compared to methanol puts the largest of the acetaldehyde splittings a factor of two below presently available Lamb-dip resolution.

  4. Hyperfine electric parameters calculation in Si samples implanted with {sup 57}Mn→{sup 57}Fe

    Energy Technology Data Exchange (ETDEWEB)

    Abreu, Y., E-mail: yabreu@ceaden.edu.cu [Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Calle 30 No. 502 e/5ta y 7ma Ave., 11300 Miramar, Playa, La Habana (Cuba); Cruz, C.M.; Piñera, I.; Leyva, A.; Cabal, A.E. [Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Calle 30 No. 502 e/5ta y 7ma Ave., 11300 Miramar, Playa, La Habana (Cuba); Van Espen, P. [Departement Chemie, Universiteit Antwerpen, Middelheimcampus, G.V.130, Groenenborgerlaan 171, 2020 Antwerpen (Belgium); Van Remortel, N. [Departement Fysica, Universiteit Antwerpen, Middelheimcampus, G.U.236, Groenenborgerlaan 171, 2020 Antwerpen (Belgium)

    2014-07-15

    Nowadays the electronic structure calculations allow the study of complex systems determining the hyperfine parameters measured at a probe atom, including the presence of crystalline defects. The hyperfine electric parameters have been measured by Mössbauer spectroscopy in silicon materials implanted with {sup 57}Mn→{sup 57}Fe ions, observing four main contributions to the spectra. Nevertheless, some ambiguities still remain in the {sup 57}Fe Mössbauer spectra interpretation in this case, regarding the damage configurations and its evolution with annealing. In the present work several implantation environments are evaluated and the {sup 57}Fe hyperfine parameters are calculated. The observed correlation among the studied local environments and the experimental observations is presented, and a tentative microscopic description of the behavior and thermal evolution of the characteristic defects local environments of the probe atoms concerning the location of vacancies and interstitial Si in the neighborhood of {sup 57}Fe ions in substitutional and interstitial sites is proposed.

  5. Powder Metallurgy characteristics and application: state of the art

    International Nuclear Information System (INIS)

    Zaid, A.I.O.

    2005-01-01

    Powder metallurgy process (P/M) is a near-net or net-shape manufacturing process that combines the features of shape making technology of powder compaction with the development of final material and design properties (physical and mechanical) during subsequent densification or consolidation processes, e.g. sintering. It utilizes the metal powder or powders of metal alloys. In this paper, the major historical developments in P/M are reviewed and discussed. The main parameters involved in the process and their effects on the product characteristics are presented and discussed, which include: powders and methods of their production, particle size and shape, compressibility and additives, sintering temperature and time and finishing processes. The advantages and limitations of powder metallurgy are also presented and discussed. Finally, applications and future developments of the process are outlined and discussed. (author)

  6. Laser powder microdeposition of CP2 Titanium

    International Nuclear Information System (INIS)

    Meacock, C.; Vilar, R.

    2008-01-01

    Laser powder microdeposition (LPMD) uses a finely focused laser beam to generate a minute meltpool on the surface of a metallic substrate into which metallic powder is blown. The laser/powder interaction zone is scanned over the substrate and molten material re-solidifies leaving microscale tracks of deposited material. The ability to deposit material on this scale opens up the possibilities of the alteration of the surface properties of small metallic components, the repair of fine damage such as fractures and wear and the fabrication of small components that require high dimensional accuracy such as dental and maxillofacial implants. In this paper, a novel Laser powder microdeposition system is described whereby the powder is fed via a fine capillary. The system was used to deposit single tracks, thin walls and a solid part of grade 2 commercially pure (CP2) Titanium, a material suitable for the fabrication of dental implants. The geometry of both single tracks and thin walls of CP2 Titanium deposited by LPMD can be controlled by variation of laser power and scanning speed. The process can be used to produce porosity free thin wall structures with widths lower than 450 μm and with a surface roughness lower than 20 μm (Ra)

  7. Production of titanium alloy powders by vacuum fusion-centrifugation

    International Nuclear Information System (INIS)

    Decours, Jacques; Devillard, Jacques; Sainfort, G.

    1975-01-01

    This work presents a method of preparing powdered TA6V and TA6Z5D alloys by fusion-centrifugation under electron bombardment. An industrial capacity apparatus for the production of metallic powders is described and the characteristics of the powders obtained are presented. Solid parts were shaped by sintering and drawing at temperatures between 850 and 1100 deg C. The structure and mechanical properties of the cold densified products before and after heat treatment are compared [fr

  8. Fabrication of metallic glass structures

    Science.gov (United States)

    Cline, C.F.

    1983-10-20

    Amorphous metal powders or ribbons are fabricated into solid shapes of appreciable thickness by the application of compaction energy. The temperature regime wherein the amorphous metal deforms by viscous flow is measured. The metal powders or ribbons are compacted within the temperature regime.

  9. Spin dynamics and hyperfine interaction in InAs semiconductor quantum dots

    International Nuclear Information System (INIS)

    Eble, B.; Krebs, O.; Voisin, P.; Lemaitre, A.; Kudelski, A.; Braun, P.F.; Lombez, L.; Marie, X.; Urbaszek, B.; Amand, T.; Lagarde, D.; Renucci, P.; Kowalik, K.; Kalevich, V.K.; Kavokin, K.V.

    2006-01-01

    We present a detailed study of the hyperfine interaction between carrier and nuclear spins in InAs semiconductor quantum dots. Time resolved measurements on excitons in positively charged quantum dots show the electron spin relaxation due to random fluctuations of the spin orientation of the nuclei in the quantum dot. A complimentary aspect of the hyperfine interaction can be uncovered in single dot continuous wave photoluminescence experiments in a weak magnetic field, namely the Overhauser shift due to the dynamic polarisation of the nuclei following excitation with circularly polarised light. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Muon capture in hyperfine states of muonic deuterium and induced pseudoscalar form factor

    International Nuclear Information System (INIS)

    Morita, M.; Morita, R.

    1992-01-01

    Muon capture rates from the hyperfine states of the muonic deuterium were studied as the functions of the induced pseudoscalar form factor g P . These capture rates vary also with the πNΔ coupling constants through the meson exchange current effects. Variation is not large, but still, appreciable to limit the magnitude of g P . The ratio of the capture rates from two hyperfine states has a small variation, and it is more sensitive to g P than the muon capture rates. (orig.)

  11. Investigation of transferred hyperfine interactions from 129I and 119Sn by Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Sanchez, J.-P.

    1976-01-01

    The hyperfine parameters at 129 I have been measured in the series of compounds CrI 3 , CsCrI 3 , MI 2 (M=V, Cr, Mn, Fe, Co, Ni, Cd) and NR 4 FeI 4 (R=ethyl, butyl). They have been interpreted in terms of the charge and spin densities in the ligand valence orbitals. Information about the spin polarization mechanisms as well as about the local magnetic and crystallographic structural arrangements have been furthermore deduced. The 119 Sn hyperfine data in the series of RESn 3 intermetallics have provided information about the magnetic structure and the spin polarization mechanisms [fr

  12. International summer school on hyperfine interactions and physics with oriented nuclei - 1985. Pt.1,2

    International Nuclear Information System (INIS)

    Rotter, M.

    1985-01-01

    Part I and part II are presented of the contributions submitted to the International study meeting on physics with oriented nuclei and of papers from the International summer school on hyperfine interactions. The contributions and papers are devoted to the present status and further development of low temperature nuclear orientation of short-lived nuclei with emphasis on online techniques. The following topics are covered: nuclear orientation, NMR/ON, level mixing and level crossing resonances, laser spectroscopy, Moessbauer spectroscopy, polarization phenomena in low, medium and high energy physics, applications of hyperfine interaction techniques in nuclear physics, atomic physics, solid state physics, biology and materials research. (Z.J.)

  13. Theory of Electric-Field Effects on Electron-Spin-Resonance Hyperfine Couplings

    International Nuclear Information System (INIS)

    Karna, S.P.

    1997-01-01

    A quantum mechanical theory of the effects of a uniform electric field on electron-spin-resonance hyperfine couplings is presented. The electric-field effects are described in terms of perturbation coefficients which can be used to probe the local symmetry as well as the strength of the electric field at paramagnetic sites in a solid. Results are presented for the first-order perturbation coefficients describing the Bloembergen effect (linear electric-field effect on hyperfine coupling tensor) for the O atom and the OH radical. copyright 1997 The American Physical Society

  14. Hyperfine coupling constants for nitroxide spin probes in water and carbon tetrachloride

    Science.gov (United States)

    Windle, J. J.

    The hyperfine coupling constants of eight commonly used nitroxide spin probes (di-t-butyl nitroxide (DTBN) and its perdeuterated analog (PDDTBN); the piperidine nitroxides, 2,2,6,6-tetramethylydine- N-oxyl (TEMPO), -4-hydroxy (TEMPOL), -4-amino (TEMPAMINE), -4-keto (TEMPONE), and -4-keto- d16 (PDTEMPONE); and 2,2,5,5-tetramethyl, 3-carbamidopyrroline-1-oxyl (TEMPYO)) were determined in water and carbon tetrachloride by EPR and, in the case of TEMPAMINE, also by NMR. Intrinsic linewidths were obtained and correlation times calculated. The use of the data to determine the hyperfine structures of probes in environments of intermediate polarity is given.

  15. Page 1 Ceramic oxide powders preparation—A novel chemical ...

    Indian Academy of Sciences (India)

    Ceramic oxide powders preparation—A novel chemical route 337. In the reported route, nanosized mixed oxides were prepared from the thermolysis of the precursor powders. The process becomes more time efficient if the precursor. Solution of metal nitrate—PVA—sucrose is boiled down to a honey like consistency and ...

  16. Pyrophoric behaviour of uranium hydride and uranium powders

    Science.gov (United States)

    Le Guyadec, F.; Génin, X.; Bayle, J. P.; Dugne, O.; Duhart-Barone, A.; Ablitzer, C.

    2010-01-01

    Thermal stability and spontaneous ignition conditions of uranium hydride and uranium metal fine powders have been studied and observed in an original and dedicated experimental device placed inside a glove box under flowing pure argon. Pure uranium hydride powder with low amount of oxide (Oxidation mechanisms are proposed.

  17. Preparation and Characterization of Nano-structured Ceramic Powders Synthesized by Emulsion Combustion Method

    International Nuclear Information System (INIS)

    Takatori, Kazumasa; Tani, Takao; Watanabe, Naoyoshi; Kamiya, Nobuo

    1999-01-01

    The emulsion combustion method (ECM), a novel powder production process, was originally developed to synthesize nano-structured metal-oxide powders. Metal ions in the aqueous droplets were rapidly oxidized by the combustion of the surrounding flammable liquid. The ECM achieved a small reaction field and a short reaction period to fabricate the submicron-sized hollow ceramic particles with extremely thin wall and chemically homogeneous ceramic powder. Alumina, zirconia, zirconia-ceria solid solutions and barium titanate were synthesized by the ECM process. Alumina and zirconia powders were characterized to be metastable in crystalline phase and hollow structure. The wall thickness of alumina was about 10 nm. The zirconia-ceria powders were found to be single-phase solid solutions for a wide composition range. These powders were characterized as equiaxed-shape, submicron-sized chemically homogeneous materials. The powder formation mechanism was investigated through the synthesis of barium titanate powder with different metal sources

  18. Powder Characterization and Optimization for Additive Manufacturing

    NARCIS (Netherlands)

    Cordova, Laura; Campos, Mónica; Tinga, Tiedo

    2017-01-01

    Achieving the optimal quality for Additive Manufactured (AM) parts does not only depend on setting the right process parameters. Material feedstock also plays an important role when aiming for high performance products. The metal AM processes that are most applicable to industry, Powder Bed Fusion

  19. Powder-Metallurgy Process And Product

    Science.gov (United States)

    Paris, Henry G.

    1988-01-01

    Rapid-solidification processing yields alloys with improved properties. Study undertaken to extend favorable property combinations of I/M 2XXX alloys through recently developed technique of rapid-solidification processing using powder metallurgy(P/M). Rapid-solidification processing involves impingement of molten metal stream onto rapidly-spinning chill block or through gas medium using gas atomization technique.

  20. Granulation of fine powder

    Science.gov (United States)

    Chen, Ching-Fong

    2016-08-09

    A mixture of fine powder including thorium oxide was converted to granulated powder by forming a first-green-body and heat treating the first-green-body at a high temperature to strengthen the first-green-body followed by granulation by crushing or milling the heat-treated first-green-body. The granulated powder was achieved by screening through a combination of sieves to achieve the desired granule size distribution. The granulated powder relies on the thermal bonding to maintain its shape and structure. The granulated powder contains no organic binder and can be stored in a radioactive or other extreme environment. The granulated powder was pressed and sintered to form a dense compact with a higher density and more uniform pore size distribution.

  1. Operation whey powder

    International Nuclear Information System (INIS)

    Brunner, E.

    1987-01-01

    The odyssey of the contaminated whey powder finally has come to an end, and the 5000 tonnes of whey now are designated for decontamination by means of an ion exchange technique. The article throws light upon the political and economic reasons that sent the whey powder off on a chaotic journey. It is worth mentioning in this context that the natural radioactivity of inorganic fertilizers is much higher than that of the whey powder in question. (HP) [de

  2. Neutron powder diffraction

    International Nuclear Information System (INIS)

    David, W.I.F.

    1990-01-01

    Neutron powder diffraction is a powerful technique that provides a detailed description of moderately complex crystal structures. This is nowhere more apparent than in the area of high temperature superconductors where neutron powder diffraction has provided precise structural and magnetic information, not only under ambient conditions but also at high and low temperatures and high pressures. Outside superconductor research, the variety of materials studied by neutron powder diffraction is equally impressive including zeolites, fast ionic conductors, permanent magnets and materials undergoing phase transitions. Recent advances that include high resolution studies and real-time crystallography are presented. Future possibilities of neutron powder diffraction are discussed

  3. Pharmaceutical powder compaction technology

    National Research Council Canada - National Science Library

    Çelik, Metin

    2011-01-01

    ... through the compaction formulation process and application. Compaction of powder constituents both active ingredient and excipients is examined to ensure consistent and reproducible disintegration and dispersion profiles...

  4. Hyperfine Quenching of the 2s2p 3P0 State of Berylliumlike Ions

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, K T; Chen, M H; Johnson, W R

    2008-03-13

    The hyperfine-induced 2s2p {sup 3}P{sub 0}-2s{sup 2} {sup 1}S{sub 0} transition rate for Be-like {sup 47}Ti{sup 18+} was recently measured in a storage-ring experiment by Schippers et al. [Phys. Rev. Lett. 98, 033001 (2007)]. The measured value of 0.56(3) s{sup -1} is almost 60% larger than the theoretical value of 0.356 s{sup -1} from a multiconfiguration Dirac-Fock calculation by Marques et al. [Phys. Rev. A 47, 929 (1993)]. In this work, we use a large-scale relativistic configuration-interaction method to calculate these hyperfine-induced rates for ions with Z = 6-92. Coherent hyperfine-quenching effects between the 2s2p {sup 1,3}P{sub 1} states are included in a perturbative as well as a radiation damping approach. Contrary to the claims of Marques et al., contributions from the {sup 1}P{sub 1} state are substantial and lead to a hyperfine-induced rate of 0.67 s{sup -1}, in better agreement with, though larger than, the measured value.

  5. Hyperfine contributions to spin-exchange frequency shifts in the hydrogen maser

    NARCIS (Netherlands)

    Verhaar, B.J.; Koelman, J.M.V.A.; Stoof, H.T.C.; Luiten, O.J.; Crampton, S.B.

    1987-01-01

    We have rigorously included hyperfine interactions during electron-spin-exchange collisions between ground state hydrogen atoms. We predict additional frequency shifts which are not compensated for by the usual methods of tuning maser cavities. These shifts are large compared to the potential

  6. Towards Measuring the Ground State Hyperfine Splitting of Antihydrogen -- A Progress Report

    CERN Document Server

    Sauerzopf, C.

    2016-06-20

    We report the successful commissioning and testing of a dedicated field-ioniser chamber for measuring principal quantum number distributions in antihydrogen as part of the ASACUSA hyperfine spectroscopy apparatus. The new chamber is combined with a beam normalisation detector that consists of plastic scintillators and a retractable passivated implanted planar silicon (PIPS) detector.

  7. Chiral extrapolation of lattice data for the hyperfine splittings of heavy mesons

    International Nuclear Information System (INIS)

    Guo, X.; Thomas, A.W.

    2002-01-01

    Full text: Hyperfine splittings between the heavy vector (D*, B*) and pseudoscalar (D, B) mesons have been calculated numerically in lattice QCD, where the pion mass (which is related to the light quark mass) is much larger than its physical value. Naive linear chiral extrapolations of the lattice data to the physical mass of the pion lead to hyperfine splittings which are smaller than experimental data. In order to extrapolate these lattice data to the physical mass of the pion more reasonably, we apply the effective chiral perturbation theory for heavy mesons, which is invariant under chiral symmetry when the light quark masses go to zero and heavy quark symmetry when the heavy quark masses go to infinity. This leads to a phenomenological functional form with three parameters to extrapolate the lattice data. It is found that the extrapolated hyperfine splittings are even smaller than those obtained using linear extrapolation. We conclude that the source of the discrepancy between lattice data for hyperfine splittings and experiment must lie in non-chiral physics

  8. Hyperfine field distributions in disordered Mn2CoSn and Mn2NiSn ...

    Indian Academy of Sciences (India)

    Unknown

    behaviour of hyperfine fields in Mn rich Heusler alloys. We have, therefore, prepared and studied Mn2CoSn and Mn2NiSn and also tested the applicability of the. Campbell–Blandin model in these alloys. Further, these alloys are known to exhibit a good amount of chemical disorder (Surikov et al 1990) and it is, therefore, ...

  9. Hybrid exchange-correlation functionals applied to hyperfine interactions at lanthanide and actinide impurities in Fe

    Czech Academy of Sciences Publication Activity Database

    Torumba, D.; Novák, Pavel; Cottenier, S.

    2008-01-01

    Roč. 77, č. 15 (2008), 155101/1-155101/13 ISSN 1098-0121 Institutional research plan: CEZ:AV0Z10100521 Keywords : hyperfine interactions * actinides * hybrid functionals Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.322, year: 2008

  10. Towards measuring the ground state hyperfine splitting of antihydrogen – a progress report

    Energy Technology Data Exchange (ETDEWEB)

    Sauerzopf, C., E-mail: clemens.sauerzopf@oeaw.ac.at; Capon, A. A.; Diermaier, M. [Stefan Meyer Institute for subatomic physics, Austrian Academy of Sciences (Austria); Dupré, P. [Atomic Physics Laboratory, RIKEN (Japan); Higashi, Y. [University of Tokyo, Institute of Physics, Graduate School of Arts and Sciences (Japan); Kaga, C. [Hiroshima University, Graduate School of Advanced Sciences of Matter (Japan); Kolbinger, B. [Stefan Meyer Institute for subatomic physics, Austrian Academy of Sciences (Austria); Leali, M. [Università di Brescia, Dipartimento di Ingegneria dell’ Informazione (Italy); Lehner, S. [Stefan Meyer Institute for subatomic physics, Austrian Academy of Sciences (Austria); Rizzini, E. Lodi [Università di Brescia, Dipartimento di Ingegneria dell’ Informazione (Italy); Malbrunot, C. [Stefan Meyer Institute for subatomic physics, Austrian Academy of Sciences (Austria); Mascagna, V. [Università di Brescia, Dipartimento di Ingegneria dell’ Informazione (Italy); Massiczek, O. [Stefan Meyer Institute for subatomic physics, Austrian Academy of Sciences (Austria); Murtagh, D. J.; Nagata, Y.; Radics, B. [Atomic Physics Laboratory, RIKEN (Japan); Simon, M. C.; Suzuki, K. [Stefan Meyer Institute for subatomic physics, Austrian Academy of Sciences (Austria); Tajima, M. [University of Tokyo, Institute of Physics, Graduate School of Arts and Sciences (Japan); Ulmer, S. [Ulmer Initiative Research Unit, RIKEN (Japan); and others

    2016-12-15

    We report the successful commissioning and testing of a dedicated field-ioniser chamber for measuring principal quantum number distributions in antihydrogen as part of the ASACUSA hyperfine spectroscopy apparatus. The new chamber is combined with a beam normalisation detector that consists of plastic scintillators and a retractable passivated implanted planar silicon (PIPS) detector.

  11. Hyperfine field and electronic structure of magnetite below the Verwey transition

    Czech Academy of Sciences Publication Activity Database

    Řezníček, R.; Chlan, V.; Štěpánková, H.; Novák, Pavel

    2015-01-01

    Roč. 91, č. 12 (2015), "125134-1"-"125134-10" ISSN 1098-0121 Institutional support: RVO:68378271 Keywords : hyperfine interactions and isotope effects * density functional theory * local density approximation * gradient and other corrections * nuclear magnetic resonance Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

  12. Hyperfine splitting in positronium to O(α7me). One-photon annihilation contribution

    International Nuclear Information System (INIS)

    Baker, M.; Penin, A.A.; Karlsruher Institut fuer Technologie; Piclum, J.; RWTH Aachen; Steinhauser, M.

    2014-02-01

    We present the complete result for the O(α 7 m e ) one-photon annihilation contribution to the hyperfine splitting of the ground state energy levels in positronium. Numerically it increases the prediction of quantum electrodynamics by 217±1 kHz.

  13. Measurement of 87Rb Rydberg-state hyperfine splitting in a room-temperature vapor cell

    NARCIS (Netherlands)

    Tauschinsky, A.; Newell, R.; van Linden van den Heuvell, H.B.; Spreeuw, R.J.C.

    2013-01-01

    We present direct measurements of the hyperfine splitting of Rydberg states in 87Rb using electromagnetically induced transparency (EIT) spectroscopy in a room-temperature vapor cell. With this method, and in spite of Doppler broadening, linewidths of 3.7 MHz FWHM, i.e., significantly below the

  14. Measurement of a hyperfine-induced spin-exchange frequency shift in atomic hydrogen

    International Nuclear Information System (INIS)

    Walsworth, R.L.; Silvera, I.F.; Mattison, E.M.; Vessot, R.F.C.

    1992-01-01

    We have measured a hyperfine-induced spin-exchange frequency shift in the atomic-hydrogen ground-state hyperfine transition. A recent quantum-mechanical treatment of low-energy hydrogen-hydrogen scattering by Koelman et al. [Phys. Rev. A 38, 3535 (1988)] predicts such frequency shifts to become large at low temperature, and to affect the performance of atomic clocks such as the cryogenic hydrogen maser. The experiment reported here was performed with a hydrogen maser operating near room temperature, where the reported hyperfine effects are predicted to be small, but measurable. Using an adiabatic fast passage (AFP) technique to vary the incoming atomic population in the masing states from approximately 100% (AFP on) to 50% (AFP off), we determined the change in the dimensionless hyperfine-induced frequency-shift parameter Ω to be Ω on -Ω off =5.38 (1.06)x10 -4 . The theoretical prediction at this temperature is Ω on -Ω off =-0.76x10 -4 to -1.12x10 -4 , for the range of masing-state populations used in the present experiment. We review the relevant theory, report our experimental method and results, and discuss possible reasons for the discrepancy between experiment and theory

  15. Measurement of the magnetic hyperfine field at the 181 Ta site in nickel matrix

    International Nuclear Information System (INIS)

    Saxena, R.N.; Carbonari, A.W.; Pendl Junior, W.; Attili, R.N.; Kenchian, G.; Soares, J.C.A.C.R.; Moreno, M.S.

    1990-01-01

    The hyperfine magnetic field on the Ta 181 nucleus were determined using the gamma-gamma perturbed angular correlation method, on a nickel matrix, with a 133-482 KeV cascade from the Hf- 181 beta minus decay. (L.C.J.A.)

  16. Hyperfine field and magnetic structure in the B phase of CeCoIn5

    Energy Technology Data Exchange (ETDEWEB)

    Graf, Matthias J [Los Alamos National Laboratory; Curro, Nicholas J [UNIV OF CAL; Young, Ben - Li [NATIONAL CHIAO UNIV; Urbano, Ricardo R [FL STATE UNIV

    2009-01-01

    We re-analyze Nuclear Magnetic Resonance (NMR) spectra observed at low temperatures and high magnetic fields in the field-induced B-phase of CeCoIn{sub 5}. The NMR spectra are consistent with incommensurate antiferromagnetic order of the Ce magnetic moments. However, we find that the spectra of the In(2) sites depend critically on the direction of the ordered moments, the ordering wavevector and the symmetry of the hyperfine coupling to the Ce spins. Assuming isotropic hyperfine coupling, the NMR spectra observed for H {parallel} [100] are consistent with magnetic order with wavevector Q = {pi}(1+{delta}/a, 1/a, 1/c) and Ce moments ordered antiferromagnetically along the [100] direction in real space. If the hyperfine coupling has dipolar symmetry, then the NMR spectra require Ce moments along the [001] direction. The dipolar scenario is also consistent with recent neutron scattering measurements that find an ordered moment of 0.15{micro}{sub B} along [001] and Q{sub n} = {pi}(1+{delta}/a, 1+{delta}c, 1/c) with incommensuration {delta} = 0.12 for field H {parallel} [1{bar 1}0]. Using these parameters, we find that the hyperfine field is consistent with both experiments. We speculate that the B phase of CeCoIn{sub 5} represents an intrinsic phase of modulated superconductivity and antiferromagnetism that can only emerge in a highly clean system.

  17. Relativistic DFT calculations of hyperfine coupling constants in the 5d hexafluorido complexes

    DEFF Research Database (Denmark)

    Haase, Pi Ariane Bresling; Repisky, Michal; Komorovsky, Stanislav

    2017-01-01

    We have investigated the performance of the most popular relativistic density functional theory methods, zeroth order regular approximation (ZORA) and 4-component Dirac-Kohn-Sham (DKS), in the calculation of the recently measured hyperfine coupling constants of ReIV and IrIV in their hexafluorido...

  18. Theoretical hyperfine structures of 19F i and 17O i

    Science.gov (United States)

    Aourir, Nouria; Nemouchi, Messaoud; Godefroid, Michel; Jönsson, Per

    2018-03-01

    Multiconfiguration Hartree-Fock (MCHF) and multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations are performed for the 2 p5P2o , 2 p4(3P ) 3 s 4P , 2 p4(3P ) 3 s 2P , and 2 p4(3P ) 3 p 4So states of 19F i to determine their hyperfine constants. Several computing strategies are considered to investigate electron correlation and relativistic effects. High-order correlation contributions are included in MCHF calculations based on single and double multireference expansions. The largest components of the single reference MCHF wave functions are selected to define the multireference (MR) sets. In this scheme, relativistic corrections are evaluated in the Breit-Pauli approximation. A similar strategy is used for the calculation of MCDHF relativistic wave functions and hyperfine parameters. While correlation and relativistic corrections are found to be rather small for the ground state, we highlight large relativistic effects on the hyperfine constant A3 /2 of 2 p4(3P ) 3 p 4So and, to a lesser extent, on A1 /2 of 2 p4(3P ) 3 s 4P . As expected for such a light system, electron correlation effects dominate over relativity in the calculation of the hyperfine interaction of all other levels considered. We also revisit the hyperfine constants of 2 p3(4S ) 3 s S5o and 2 p3(4S ) 3 p 5P in 17O using similar strategies. The results are found to be in excellent agreement with experiment.

  19. Dispersion-strengthened Aluminium Products Manufactured by Powder Blending

    DEFF Research Database (Denmark)

    Hansen, Niels

    1969-01-01

    Detailed experiments carried out to examine relationship between microstructure and mechanical properties of powder-blended aluminum products are reported; their results as well as structural studies by transmission electron microscopy and tensile-and creep- testing, are given; as dispersed phase......, various oxide powders were selected on criterion that during manufacturing no reaction must taken place between metal and oxide phase; strength of powder-blended aluminum products increases and elongation decreases with decreasing particle size of aluminum powder and with increasing concentration of oxide...... phase....

  20. Benefits of Hot Isostatic Pressure/Powdered Metal (HIP/PM) and Additive Manufacturing (AM) To Fabricate Advanced Energy System Components

    Energy Technology Data Exchange (ETDEWEB)

    Horton, Nancy [Energy Industries of Ohio, Cleveland, OH (United States); Sheppard, Roy [Energy Industries of Ohio, Cleveland, OH (United States)

    2016-12-31

    Advanced Energy systems require large, complex components produced from materials capable of withstanding severe operating environments (high temperature, pressure, corrosivity). Such parts can be difficult to source, as conventional material processing technologies must be tailored to ensure a safe and cost effective approach to large-scale manufacture of quality structural advanced alloy components that meet the performance specifications of AE systems. (HIP/PM) has shown advantages over other manufacturing methods when working with these materials. For example, using HIP’ing in lieu of casting means significant savings in raw material costs, which for expensive, high-nickel alloys can be considerable for large-scale production. Use of HIP/PM also eliminates the difficulties resulting from reactivity of these materials in the molten state and facilitates manufacture of the large size requirements of the AE industry, producing a part that is defect and porosity free, thus further reducing or eliminating time and expense of post processing machining and weld repair. New advances in Additive Manufacturing (AM) techniques make it possible to further expand the benefits of HIP/PM in producing AE system components to create an even more robust manufacturing approach. Traditional techniques of welding and forming sheet metal to produce the HIP canisters can be time consuming and costly, with limitations on the complexity of part which can be achieved. A key benefit of AM is the freedom of design that it offers, so use of AM could overcome such challenges, ultimately enabling redesign of complete energy systems. A critical step toward this goal is material characterization of the required advanced alloys, for use in AM. Using Haynes 282, a high nickel alloy of interest to the Fossil Energy community, particularly for Advanced-UltraSuperCritical (AUSC) operating environments, as well as the crosscutting interests of the aerospace, defense and medical markets, this

  1. Classification of tungsten powder by fluidization method and its application

    International Nuclear Information System (INIS)

    Li Khan-Guan'.

    1989-01-01

    Search for accessible in practice, the technological method to increase the level of control of the granulometric composition of tungsten powder and to increase quality of products and to prepare new materials is carried out. It is shown that the method of fluidization is effective and accessible in practice for tungsten powder (and other refractory metals and compounds) classification, that increases the level of control of the granulometric composition of the powder and thus - its quality, and that improves control of properties of tungsten and other refractory metal products

  2. Preparation of copper and silicon/copper powders by a gas ...

    Indian Academy of Sciences (India)

    Administrator

    carrier gas and precipitated as spherical Cu metal and Si/Cu composite powders. The mean diameter of the resulting powder was 100–200 nm. Keywords. Copper powder; Si/Cu composite particle; gas evaporation–condensation method; characteriza- tion. 1. ... important role in electronics, catalysts, resins, and ther-.

  3. Fabricating solid carbon porous electrodes from powders

    Science.gov (United States)

    Kaschmitter, James L.; Tran, Tri D.; Feikert, John H.; Mayer, Steven T.

    1997-01-01

    Fabrication of conductive solid porous carbon electrodes for use in batteries, double layer capacitors, fuel cells, capacitive dionization, and waste treatment. Electrodes fabricated from low surface area (Electrodes having a higher surface area, fabricated from powdered carbon blacks, such as carbon aerogel powder, carbon aerogel microspheres, activated carbons, etc. yield high conductivity carbon compositives with excellent double layer capacity, and can be used in double layer capacitors, or for capacitive deionization and/or waste treatment of liquid streams. By adding metallic catalysts to be high surface area carbons, fuel cell electrodes can be produced.

  4. The temperature dependence of the hyperfine fields of nickel, copper and zinc in nickel near the Curie temperature

    International Nuclear Information System (INIS)

    Zeitz, W.D.

    1974-01-01

    Hyperfine field investigations were made to determine the critical exponent β in Nickel metals as in pure 63 NiNi system as in two systems 66 CuNi and 67 ZnNi. The experimental method was the time-differential observation of the perturbed angular correlation of gammas after a nuclear reaction. The isomeric states 63 Ni: 5/2 - for 87.2 keV, tau = 2.49 μs, g = 0.301; 66 Cu: 6 - for 1154.1 keV, tau = 860 ns, g = 0.1733; 67 Zn: 9/2 + for 605 keV, tau = 480 ns, g = 0.243 were excited in (d,p), ( 3 He,p) and (α,n) nuclear reactions on the isotope rich 62 Ni and 64 Ni. A new developed fast electron beam heating cared for a sufficient temperature stability in the range up to 1 0 below the Curie point. (orig./WL) [de

  5. Torsionally mediated spin-rotation hyperfine splittings at moderate to high J values in methanol

    Science.gov (United States)

    Belov, S. P.; Golubiatnikov, G. Yu.; Lapinov, A. V.; Ilyushin, V. V.; Alekseev, E. A.; Mescheryakov, A. A.; Hougen, J. T.; Xu, Li-Hong

    2016-07-01

    This paper presents an explanation based on torsionally mediated proton-spin-overall-rotation interaction for the observation of doublet hyperfine splittings in some Lamb-dip sub-millimeter-wave transitions between ground-state torsion-rotation states of E symmetry in methanol. These unexpected doublet splittings, some as large as 70 kHz, were observed for rotational quantum numbers in the range of J = 13 to 34, and K = - 2 to +3. Because they increase nearly linearly with J for a given branch, we confined our search for an explanation to hyperfine operators containing one nuclear-spin angular momentum factor I and one overall-rotation angular momentum factor J (i.e., to spin-rotation operators) and ignored both spin-spin and spin-torsion operators, since they contain no rotational angular momentum operator. Furthermore, since traditional spin-rotation operators did not seem capable of explaining the observed splittings, we constructed totally symmetric "torsionally mediated spin-rotation operators" by multiplying the E-species spin-rotation operator by an E-species torsional-coordinate factor of the form e±niα. The resulting operator is capable of connecting the two components of a degenerate torsion-rotation E state. This has the effect of turning the hyperfine splitting pattern upside down for some nuclear-spin states, which leads to bottom-to-top and top-to-bottom hyperfine selection rules for some transitions, and thus to an explanation for the unexpectedly large observed hyperfine splittings. The constructed operator cannot contribute to hyperfine splittings in the A-species manifold because its matrix elements within the set of torsion-rotation A1 and A2 states are all zero. The theory developed here fits the observed large doublet splittings to a root-mean-square residual of less than 1 kHz and predicts unresolvable splittings for a number of transitions in which no doublet splitting was detected.

  6. Torsionally mediated spin-rotation hyperfine splittings at moderate to high J values in methanol

    International Nuclear Information System (INIS)

    Belov, S. P.; Golubiatnikov, G. Yu.; Lapinov, A. V.; Ilyushin, V. V.; Mescheryakov, A. A.; Alekseev, E. A.; Hougen, J. T.; Xu, Li-Hong

    2016-01-01

    This paper presents an explanation based on torsionally mediated proton-spin–overall-rotation interaction for the observation of doublet hyperfine splittings in some Lamb-dip sub-millimeter-wave transitions between ground-state torsion-rotation states of E symmetry in methanol. These unexpected doublet splittings, some as large as 70 kHz, were observed for rotational quantum numbers in the range of J = 13 to 34, and K = − 2 to +3. Because they increase nearly linearly with J for a given branch, we confined our search for an explanation to hyperfine operators containing one nuclear-spin angular momentum factor I and one overall-rotation angular momentum factor J (i.e., to spin-rotation operators) and ignored both spin-spin and spin-torsion operators, since they contain no rotational angular momentum operator. Furthermore, since traditional spin-rotation operators did not seem capable of explaining the observed splittings, we constructed totally symmetric “torsionally mediated spin-rotation operators” by multiplying the E-species spin-rotation operator by an E-species torsional-coordinate factor of the form e ±niα . The resulting operator is capable of connecting the two components of a degenerate torsion-rotation E state. This has the effect of turning the hyperfine splitting pattern upside down for some nuclear-spin states, which leads to bottom-to-top and top-to-bottom hyperfine selection rules for some transitions, and thus to an explanation for the unexpectedly large observed hyperfine splittings. The constructed operator cannot contribute to hyperfine splittings in the A-species manifold because its matrix elements within the set of torsion-rotation A 1 and A 2 states are all zero. The theory developed here fits the observed large doublet splittings to a root-mean-square residual of less than 1 kHz and predicts unresolvable splittings for a number of transitions in which no doublet splitting was detected.

  7. OIL SOLUTIONS POWDER

    Science.gov (United States)

    Technical product bulletin: aka OIL SOLUTIONS POWDER, SPILL GREEN LS, this miscellaneous oil spill control agent used in cleanups initially behaves like a synthetic sorbent, then as a solidifier as the molecular microencapsulating process occurs.

  8. Magnetically responsive enzyme powders

    Science.gov (United States)

    Pospiskova, Kristyna; Safarik, Ivo

    2015-04-01

    Powdered enzymes were transformed into their insoluble magnetic derivatives retaining their catalytic activity. Enzyme powders (e.g., trypsin and lipase) were suspended in various liquid media not allowing their solubilization (e.g., saturated ammonium sulfate and highly concentrated polyethylene glycol solutions, ethanol, methanol, 2-propanol) and subsequently cross-linked with glutaraldehyde. Magnetic modification was successfully performed at low temperature in a freezer (-20 °C) using magnetic iron oxides nano- and microparticles prepared by microwave-assisted synthesis from ferrous sulfate. Magnetized cross-linked enzyme powders were stable at least for two months in water suspension without leakage of fixed magnetic particles. Operational stability of magnetically responsive enzymes during eight repeated reaction cycles was generally without loss of enzyme activity. Separation of magnetically modified cross-linked powdered enzymes from reaction mixtures was significantly simplified due to their magnetic properties.

  9. Towards isotope shift and hyperfine structure measurements of the element nobelium

    Energy Technology Data Exchange (ETDEWEB)

    Chhetri, Premaditya; Lautenschlaeger, Felix; Walther, Thomas [Institut fuer Angewandte Physik, TU Darmstadt, D-64289 Darmstadt (Germany); Laatiaoui, Mustapha [Helmholtz Institut Mainz, D-55099 Mainz (Germany); Block, Michael; Hessberger, Fritz-Peter [Helmholtz Institut Mainz, D-55099 Mainz (Germany); GSI, D-64291 Darmstadt (Germany); Lauth, Werner; Backe, Hartmut [Institut fuer Kernphysik, JGU Mainz, D-55122 Mainz (Germany); Kunz, Peter [TRIUMF, D-V6T2A3 Vancouver (Canada)

    2014-07-01

    Laser spectroscopy on the heaviest elements is of great interest as it allows the study of the evolution of relativistic effects on their atomic structure. In our experiment we exploit the Radiation Detected Resonance Ionization Spectroscopy technique and use excimer-laser pumped dye lasers to search for the first time the {sup 1}P{sub 1} level in {sup 254}No. Etalons will be used in the forthcoming experiments at GSI, Darmstadt, to narrow down the bandwidth of the dye lasers to 0.04 cm{sup -1}, for the determination of the isotope shift and hyperfine splitting of {sup 253,} {sup 255}No. In this talk results from preparatory hyperfine structure studies in nat. ytterbium and the perspectives for future experiments of the heaviest elements are discussed.

  10. Fine- and hyperfine structure investigations of the even-parity configuration system of the atomic holmium

    Science.gov (United States)

    Stefanska, D.; Ruczkowski, J.; Elantkowska, M.; Furmann, B.

    2018-04-01

    In this work new experimental results concerning the hyperfine structure (hfs) for the even-parity level system of the holmium atom (Ho I) were obtained; additionally, hfs data obtained recently as a by-product in investigations of the odd-parity level system were summarized. In the present work the values of the magnetic dipole and the electric quadrupole hfs constants A and B were determined for 24 even-parity levels, for 14 of them for the first time. On the basis of these results, as well as on available literature data, a parametric study of the fine structure and the hyperfine structure for the even-parity configurations of atomic holmium was performed. A multi-configuration fit of 7 configurations was carried out, taking into account second-order of the perturbation theory. For unknown electronic levels predicted values of the level energies and hfs constants are given, which can facilitate further experimental investigations.

  11. Transferred hyperfine fields at the Y sites in Y-Co compounds

    International Nuclear Information System (INIS)

    Figiel, H.; Oppelt, A.; Dormann, E.; Buschow, K.H.J.

    1976-01-01

    The Y hyperfine fields in YCo 3 , Y 2 Co 7 , YCo 5 , and Y 2 Co 17 are derived by means of NMR spin echo measurements. They are closely correlated to the different crystallographic sites of the Y atoms but seem not to be related to the magnitude of the magnetic moments of the surrounding Co neighbours. This may be indicative of a short range Co-Y hyperfine interaction. For Y 2 Co 17 the pure hexagonal stacking did not occur, stacking faults and/or disorder between Co dumb-bells and Y atoms being always present. Y 2 Co 17 could be stabilized almost completely, however, in the rhombohedral structure. (author)

  12. Hyperfine excitation of CH in collisions with atomic and molecular hydrogen

    Science.gov (United States)

    Dagdigian, Paul J.

    2018-04-01

    We investigate here the excitation of methylidene (CH) induced by collisions with atomic and molecular hydrogen (H and H2). The hyperfine-resolved rate coefficients were obtained from close coupling nuclear-spin-free scattering calculations. The calculations are based upon recent, high-accuracy calculations of the CH(X2Π)-H(2S) and CH(X2Π)-H2 potential energy surfaces. Cross-sections and rate coefficients for collisions with atomic H, para-H2, and ortho-H2 were computed for all transitions between the 32 hyperfine levels for CH(X2Π) involving the n ≤ 4 rotational levels for temperatures between 10 and 300 K. These rate coefficients should significantly aid in the interpretation of astronomical observations of CH spectra. As a first application, the excitation of CH is simulated for conditions in typical molecular clouds.

  13. Lamb shifts and hyperfine structure in 6Li+ and 7Li+: Theory and experiment

    DEFF Research Database (Denmark)

    Riis, E.; Sinclair, A. G.; Poulsen, Ove

    1994-01-01

    High-precision laser-resonance measurements accurate to +/-0.5 MHz, or better are reported for transitions among the 1s2s S-3(1)-1s2p P-3(J) hyperfine manifolds for each of J = 0, 1, and 2 in both Li-6(+) and Li-7(+). A detailed analysis of hyperfine structure is performed for both the S and P......-order non-QED contributions to the transition frequencies are subtracted from the measurements to obtain the residual QED shifts. The isotope-averaged and spin-averaged effective shift for Li-7(+) is 37 429.40 +/- 0.39 MHz, with an additional uncertainty of +/-1.5 MHs due to finite nuclear size corrections...

  14. Ro-vibrational averaging of the isotropic hyperfine coupling constant for the methyl radical

    Energy Technology Data Exchange (ETDEWEB)

    Adam, Ahmad Y.; Jensen, Per, E-mail: jensen@uni-wuppertal.de [Fakultät Mathematik und Naturwissenschaften, Physikalische und Theoretische Chemie, Bergische Universität Wuppertal, D-42097 Wuppertal (Germany); Yachmenev, Andrey; Yurchenko, Sergei N. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)

    2015-12-28

    We present the first variational calculation of the isotropic hyperfine coupling constant of the carbon-13 atom in the CH{sub 3} radical for temperatures T = 0, 96, and 300 K. It is based on a newly calculated high level ab initio potential energy surface and hyperfine coupling constant surface of CH{sub 3} in the ground electronic state. The ro-vibrational energy levels, expectation values for the coupling constant, and its temperature dependence were calculated variationally by using the methods implemented in the computer program TROVE. Vibrational energies and vibrational and temperature effects for coupling constant are found to be in very good agreement with the available experimental data. We found, in agreement with previous studies, that the vibrational effects constitute about 44% of the constant’s equilibrium value, originating mainly from the large amplitude out-of-plane bending motion and that the temperature effects play a minor role.

  15. Ro-vibrational averaging of the isotropic hyperfine coupling constant for the methyl radical

    Science.gov (United States)

    Adam, Ahmad Y.; Yachmenev, Andrey; Yurchenko, Sergei N.; Jensen, Per

    2015-12-01

    We present the first variational calculation of the isotropic hyperfine coupling constant of the carbon-13 atom in the CH3 radical for temperatures T = 0, 96, and 300 K. It is based on a newly calculated high level ab initio potential energy surface and hyperfine coupling constant surface of CH3 in the ground electronic state. The ro-vibrational energy levels, expectation values for the coupling constant, and its temperature dependence were calculated variationally by using the methods implemented in the computer program TROVE. Vibrational energies and vibrational and temperature effects for coupling constant are found to be in very good agreement with the available experimental data. We found, in agreement with previous studies, that the vibrational effects constitute about 44% of the constant's equilibrium value, originating mainly from the large amplitude out-of-plane bending motion and that the temperature effects play a minor role.

  16. Ro-vibrational averaging of the isotropic hyperfine coupling constant for the methyl radical

    International Nuclear Information System (INIS)

    Adam, Ahmad Y.; Jensen, Per; Yachmenev, Andrey; Yurchenko, Sergei N.

    2015-01-01

    We present the first variational calculation of the isotropic hyperfine coupling constant of the carbon-13 atom in the CH 3 radical for temperatures T = 0, 96, and 300 K. It is based on a newly calculated high level ab initio potential energy surface and hyperfine coupling constant surface of CH 3 in the ground electronic state. The ro-vibrational energy levels, expectation values for the coupling constant, and its temperature dependence were calculated variationally by using the methods implemented in the computer program TROVE. Vibrational energies and vibrational and temperature effects for coupling constant are found to be in very good agreement with the available experimental data. We found, in agreement with previous studies, that the vibrational effects constitute about 44% of the constant’s equilibrium value, originating mainly from the large amplitude out-of-plane bending motion and that the temperature effects play a minor role

  17. Development of atomic spectroscopy technologies - Hyperfine structure of 2 period atoms using optogalvanic effects

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Nam Ic [Hankuk University of foreign studies, Seoul (Korea)

    2000-03-01

    The source of anomalous broad linewidth of 3{sup 3}P{sub 1},{sub 2},{sub 3}-3{sup 3}D{sub 2},{sub 3},4(3s') transition was explained. The broad optogalvanic spectrum was consisted of two gaussian peaks of different linewidths, and they are separated by 250 MHz. The Narrow peak, which has linewidth of room temperature, is from oxygen atoms already separated, and the shifted broad peak, which has linewidth corresponding to a temperature of 9000 K, is from weakly bound molecular ions. Obtained hyperfine spectrum of fluorine atom at the expected frequency, was too weak to analyze hyperfine structure constants. Microwave discharge might be necessary for higher density of excited state. 16 refs., 11 figs. (Author)

  18. Hyperfine characterization of the Ba Ti1-x Hfx O3 for x = 0.20

    International Nuclear Information System (INIS)

    Ayala, Alexandro; Lopez-Garcia, Alberto

    1996-01-01

    It is known that the cation substitution in perovskites produce changes in the macroscopic properties of these materials. A case to study is for example the influence of cation B partially substituted by cation B ' when ABO 3 is ferroelectric, and A B ' O 3 is paraelectric. In this work the system Ba Ti 1-x Hf x O 3 with x = 0.05, 0.10, 0.15 and 0.20 is studied by Perturbed Angular Correlations (Pac) in order to obtain microscopic information through the electric field gradient tensor (EFG) produced by electrons close to probes. Two hyperfine quadrupole interactions were detected. One interaction associated to probes with defects originated during the nuclear processes after neutron irradiation, and the other are located in B sites. At R T, the hyperfine parameters are analyzed in terms of Hf concentration. (author)

  19. Hyperfine-structure measurements in bismuth using a Fourier-transform spectrometer

    International Nuclear Information System (INIS)

    George, S.; Munsee, J.H.; Verges, J.

    1985-01-01

    The spectrum of neutral bismuth has been studied in the infrared region by means of the Fourier-transform spectrometer at the Laboratoire Aime Cotton, Orsay, France. A microwave-excited discharge tube containing bismuth iodide was used as the light source. A total of 37 hyperfine structures was studied. Precise measurements of the center of gravity of the structures give energy levels with an error less than 0.005 m -1 . Complete analysis of these hyperfine structures resulted in the determination of the magnetic-dipole and the electric-quadrupole interaction constants for 10 even and 12 odd levels. The present results have increased the number of newly classified lines to 78, as compared with 28 reported in our earlier work [J. Opt. Soc. Am. 72, 589 (1982)]. The analysis has also resulted in the confirmation an the assignment of many J values, improved values of energy levels, and two new levels

  20. Investigation of hyperfine interactions in DNA and antibody of different lineages of mice infected by T. cruzi by perturbed gamma-gamma angular correlation spectroscopy; Investigacao de interacoes hiperfinas em DNA e anticorpos de diferentes linhagens de camundongos frente a infeccao por T. cruzi pela epectroscopia de correlacao angular gama-gama perturbada

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Andreia dos Santos

    2012-07-01

    In the present work perturbed angular correlation (PAC) spectroscopy was used to measured electric quadrupole interactions in DNA biomolecules of different mice lineages (A/J, C57BL/6, B6AF1, BXA1 e BXA2), samples of different isotypes of immunoglobulin G (IgG1, IgG2a e IgG2b) and active portions of complete and fragmented immunoglobulin responsible by the immune response. Electric quadrupole interactions were also measured in DNA nitrogenous bases (adenine, cytosine, guanine, thymine). PAC measurements were performed using {sup 111}In {yields} {sup 111C}d; {sup 111mC}d {yields} {sup 111}Cd; {sup 111}Ag {yields} {sup 111}Cd; e {sup 181}Hf {yields} {sup 181}Ta as probe nuclei, and carried out at room temperature and liquid nitrogen temperature, in order to investigate dynamic and static hyperfine interactions, respectively. The biomolecule samples were directly marked with the radioactive parent nuclei, whose atom link to a certain site in the biomolecules. The biological materials as well as the probe nuclei were chosen to investigate the possibility to use PAC spectroscopy to measure hyperfine parameters at nuclei from metallic elements bound to biomolecules (including the use of different probe nuclei produced in the decay of parent nuclei of four different metals) and also to study the behavior of different biomolecules by means of the measured hyperfine parameters. Results show differences in the hyperfine interactions of probe nuclei bound to the studied biomolecules. Such differences were observed by variations in the hyperfine parameters, which depend on the type of biomolecule and the results also show that the probe nuclei atom bound to the molecule in some cases and in others do not. (author)

  1. Fine- and hyperfine structure investigations of even configuration system of atomic terbium

    Science.gov (United States)

    Stefanska, D.; Elantkowska, M.; Ruczkowski, J.; Furmann, B.

    2017-03-01

    In this work a parametric study of the fine structure (fs) and the hyperfine structure (hfs) for the even-parity configurations of atomic terbium (Tb I) is presented, based in considerable part on the new experimental results. Measurements on 134 spectral lines were performed by laser induced fluorescence (LIF) in a hollow cathode discharge lamp; on this basis, the hyperfine structure constants A and B were determined for 52 even-parity levels belonging to the configurations 4f85d6s2, 4f85d26s or 4f96s6p; in all the cases those levels were involved in the transitions investigated as the lower levels. For 40 levels the hfs was examined for the first time, and for the remaining 12 levels the new measurements supplement our earlier results. As a by-product, also preliminary values of the hfs constants for 84 odd-parity levels were determined (the investigations of the odd-parity levels system in the terbium atom are still in progress). This huge amount of new experimental data, supplemented by our earlier published results, were considered for the fine and hyperfine structure analysis. A multi-configuration fit of 7 configurations was performed, taking into account second-order of perturbation theory, including the effects of closed shell-open shell excitations. Predicted values of the level energies, as well as of magnetic dipole and electric quadrupole hyperfine structure constants A and B, are quoted in cases when no experimental values are available. By combining our experimental data with our own semi-empirical procedure it was possible to identify correctly the lower and upper level of the line 544.1440 nm measured by Childs with the use of the atomic-beam laser-rf double-resonance technique (Childs, J Opt Soc Am B 9;1992:191-6).

  2. Hyperfine Level Interactions of Diamond Nitrogen Vacancy Ensembles Under Transverse Magnetic Fields

    Science.gov (United States)

    2015-10-06

    transverse mag- netic bias field (B|| or B⊥) lifts this degeneracy, ener- getically separating the spin states and increasing sensi- tivity to magnetic or...light-trapping diamond waveguide geometry [19]. We lift the ms = ±1 degeneracy by ap- plying a static magnetic field and tune the microwave ex- citation...Hyperfine level interactions of diamond nitrogen vacancy ensembles under transverse magnetic fields Hannah Clevenson,1, 2, ∗ Edward H. Chen,1, 2

  3. Hyperfine interactions of {beta}-emitter {sup 12}N in TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Maruyama, Yukiko [Osaka Univ., Toyonaka (Japan). Faculty of Science; Izumikawa, Takuji; Tanigaki, Minoru [and others

    1997-03-01

    Hyperfine interactions of {beta}-emitter {sup 12}N (I{sup {pi}} = 1{sup -}, T{sub 1/2} 11ms) in TiO{sub 2} has been studied. A {beta}-NMR spectrum on the polarized {sup 12}N implanted in TiO{sub 2} shows that {sup 12}N are located at two different sites and maintain about 100% of initial polarization. These are the first phenomena observed in ionic crystals. (author)

  4. New precise measurement of muonium hyperfine structure interval at J-PARC

    Energy Technology Data Exchange (ETDEWEB)

    Ueno, Y., E-mail: yueno@radphys4.c.u-tokyo.ac.jp [University of Tokyo, Graduate School of Arts and Sciences (Japan); Aoki, M. [Osaka University, Graduate School of Science (Japan); Fukao, Y. [KEK (Japan); Higashi, Y.; Higuchi, T. [University of Tokyo, Graduate School of Arts and Sciences (Japan); Iinuma, H.; Ikedo, Y. [KEK (Japan); Ishida, K. [RIKEN (Japan); Ito, T. U. [Japan Atomic Energy Agency (Japan); Iwasaki, M. [RIKEN (Japan); Kadono, R. [KEK (Japan); Kamigaito, O. [RIKEN (Japan); Kanda, S. [University of Tokyo, Department of Physics (Japan); Kawall, D. [University of Massachusetts, Amherst, Department of Physics (United States); Kawamura, N.; Koda, A.; Kojima, K. M. [KEK (Japan); Kubo, M. K. [International Christian University, Graduate School of Arts and Science (Japan); Matsuda, Y. [University of Tokyo, Graduate School of Arts and Sciences (Japan); Mibe, T. [KEK (Japan); and others

    2017-11-15

    MuSEUM is an international collaboration aiming at a new precise measurement of the muonium hyperfine structure at J-PARC (Japan Proton Accelerator Research Complex). Utilizing its intense pulsed muon beam, we expect a ten-fold improvement for both measurements at high magnetic field and zero magnetic field. We have developed a sophisticated monitoring system, including a beam profile monitor to measure the 3D distribution of muonium atoms to suppress the systematic uncertainty.

  5. Hyperfine coupling in gadolinium-praseodymium alloys by specific heat measurements

    International Nuclear Information System (INIS)

    Michel, J.

    1969-01-01

    We have studied the hyperfine coupling in gadolinium-praseodymium alloys by specific heat measurements down to 0.3 K. In the first part we describe the apparatus used to perform our measurements. The second part is devoted to some theoretical considerations. We have studied in detail the case of praseodymium which is an exception in the rare earth series. The third part shows the results we have obtained. (author) [fr

  6. Computation of the hyperfine structure in the (α-μ- e-)0 atom

    International Nuclear Information System (INIS)

    Amusia, M.Ya.; Kuchiev, M.Ju.; Yakhontov, V.L.

    1983-01-01

    Computation of the ground-state hyperfine splitting of neutral muonic helium (α-μ - e - ) 0 has been carried out. Account of two terms in the expansion of this quantity in power series of a small parameter #betta# of the order of msub(e)/msub(μ) of the order of 1/200 results in the energy splitting value δ#betta# = 4462.9 MHz in good agreement with previously obtained experimental and theoretical values. (author)

  7. Hyperfine field distributions in disordered Mn2CoSn and Mn2NiSn ...

    Indian Academy of Sciences (India)

    Unknown

    4 µB magnetic moment, while Co carries moments rang- ing between 0⋅3 and 1 µB, depending on the Z element. (Webster and Ziebeck 1973). The Blandin– ..... Blue J W, Silva M T X and Vasquez A 1983 Hyperfine Inter- act. 15/16 685. Ritcey S P and Dunlap R A 1984 J. Appl. Phys. 55 2051. Surikov V V, Zhordochkin V N ...

  8. High speed forging of solid powder discs of large slenderness ratio

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    manufacturing processes such as casting, machining etc. In this new technology, sintered porous powder preforms are used as starting materials in metal forming processes. Metal- powder products manufactured by ... because of the introduction of new and fast deformation processes. Since speed is an impor- tant factor ...

  9. Magnetically responsive enzyme powders

    International Nuclear Information System (INIS)

    Pospiskova, Kristyna; Safarik, Ivo

    2015-01-01

    Powdered enzymes were transformed into their insoluble magnetic derivatives retaining their catalytic activity. Enzyme powders (e.g., trypsin and lipase) were suspended in various liquid media not allowing their solubilization (e.g., saturated ammonium sulfate and highly concentrated polyethylene glycol solutions, ethanol, methanol, 2-propanol) and subsequently cross-linked with glutaraldehyde. Magnetic modification was successfully performed at low temperature in a freezer (−20 °C) using magnetic iron oxides nano- and microparticles prepared by microwave-assisted synthesis from ferrous sulfate. Magnetized cross-linked enzyme powders were stable at least for two months in water suspension without leakage of fixed magnetic particles. Operational stability of magnetically responsive enzymes during eight repeated reaction cycles was generally without loss of enzyme activity. Separation of magnetically modified cross-linked powdered enzymes from reaction mixtures was significantly simplified due to their magnetic properties. - Highlights: • Cross-linked enzyme powders were prepared in various liquid media. • Insoluble enzymes were magnetized using iron oxides particles. • Magnetic iron oxides particles were prepared by microwave-assisted synthesis. • Magnetic modification was performed under low (freezing) temperature. • Cross-linked powdered trypsin and lipase can be used repeatedly for reaction

  10. Characteristics of Inconel Powders for Powder-Bed Additive Manufacturing

    Directory of Open Access Journals (Sweden)

    Quy Bau Nguyen

    2017-10-01

    Full Text Available In this study, the flow characteristics and behaviors of virgin and recycled Inconel powder for powder-bed additive manufacturing (AM were studied using different powder characterization techniques. The results revealed that the particle size distribution (PSD for the selective laser melting (SLM process is typically in the range from 15 μm to 63 μm. The flow rate of virgin Inconel powder is around 28 s·(50 g−1. In addition, the packing density was found to be 60%. The rheological test results indicate that the virgin powder has reasonably good flowability compared with the recycled powder. The inter-relation between the powder characteristics is discussed herein. A propeller was successfully printed using the powder. The results suggest that Inconel powder is suitable for AM and can be a good reference for researchers who attempt to produce AM powders.

  11. Composite with a metallic matrix Al-AlN: from the powder to the material; Composite a matrice metallique A1-A1N: de la poudre au materiau

    Energy Technology Data Exchange (ETDEWEB)

    Troadec, C.

    1996-05-09

    Two types of powders are used: a `composite` powder synthesized by direct nitridation of aluminium by nitrogen, and a `mixed` powder obtained by a mixture of Al and AlN powders. These two powders types are crushed in a high energetic planetary crusher under an Ar atmosphere, then they are sintered under solid phase hot pressure. Microstructure of these materials, studied by Tem and XED, is relatively heterogenous, with high density polycrystalline area and high porous nano-crystals area. Size of these porous area are higher in `mixed` powders, and is linked to AlN percentage and to the crushing time. High density area are composed of Al grains surrounded by AlN nano-crystals with Al{sub 2}O{sub 3} needles and few aluminium oxynitride crystals. Physicochemical and mechanical properties, wear and corrosion comportment differ in function of the initial powders (`mixed` or `composite`) and with the AlN percentage. These new materials have, at similar reinforcement concentration, equivalent properties to Al/SiC or Al/Al{sub 2}O{sub 3} materials. (A.B.) 112 refs.

  12. Relativistic many-body calculation of energies, lifetimes, hyperfine constants, and polarizabilities in 7Li

    International Nuclear Information System (INIS)

    Johnson, W. R.; Safronova, U. I.; Derevianko, A.; Safronova, M. S.

    2008-01-01

    The excitation energies of ns, np, nd, and nf (n≤6) states in neutral lithium are evaluated within the framework of relativistic many-body theory. First-, second-, third-, and all-order Coulomb energies and first- and second-order Breit corrections to energies are calculated. All-order calculations of reduced matrix elements, oscillator strengths, transition rates, and lifetimes are given for levels up to n=4. Electric-dipole (2s-np), electric-quadrupole (2s-nd), and electric-octupole (2s-nf), matrix elements are evaluated to obtain the corresponding ground-state multipole polarizabilities using the sum-over-states approach. Scalar and tensor polarizabilities for the 2p 1/2 and 2p 3/2 states are also calculated. Magnetic-dipole hyperfine constants A are determined for low-lying levels up to n=4. The quadratic Stark shift for the (F=2 M=0)↔(F=1 M=0) ground-state hyperfine transition is found to be -0.0582 Hz/(kV/cm) 2 , in slight disagreement with the experimental value -0.061±0.002 Hz/(kV/cm) 2 . Matrix elements used in evaluating polarizabilities, hyperfine constants, and the quadratic Stark shift are obtained using the all-order method

  13. Calculation of the hyperfine interaction using an effective-operator form of many-body theory

    International Nuclear Information System (INIS)

    Garpman, S.; Lindgren, I.; Lindgren, J.; Morrison, J.

    1975-01-01

    The effective-operator form of many-body theory is reviewed and applied to the calculation of the hyperfine structure. Numerical results are given for the 2p, 3p, and 4p excited states of Li and the 3p state of Na. This is the first complete calculation of the hyperfine structure using an effective-operator form of perturbation theory. As in the Brueckner-Goldstone form of many-body theory, the various terms in the perturbation expansion are represented by Feynman diagrams which correspond to basic physical processes. The angular part of the perturbation diagrams are evaluated by taking advantage of the formal analogy between the Feynman diagrams and the angular-momentum diagrams, introduced by Jucys et al. The radial part of the diagrams is calculated by solving one- and two-particle equations for the particular linear combination of excited states that contribute to the Feynman diagrams. In this way all second- and third-order effects are accurately evaluated without explicitly constructing the excited orbitals. For the 2p state of Li our results are in agreement with the calculations of Nesbet and of Hameed and Foley. However, our quadrupole calculation disagrees with the work of Das and co-workers. The many-body results for Li and Na are compared with semiempirical methods for evaluating the quadrupole moment from the hyperfine interaction, and a new quadrupole moment of 23 Na is given

  14. New Nuclear Magnetic Moment of 209Bi: Resolving the Bismuth Hyperfine Puzzle

    Science.gov (United States)

    Skripnikov, Leonid V.; Schmidt, Stefan; Ullmann, Johannes; Geppert, Christopher; Kraus, Florian; Kresse, Benjamin; Nörtershäuser, Wilfried; Privalov, Alexei F.; Scheibe, Benjamin; Shabaev, Vladimir M.; Vogel, Michael; Volotka, Andrey V.

    2018-03-01

    A recent measurement of the hyperfine splitting in the ground state of Li-like 80+208Bi has established a "hyperfine puzzle"—the experimental result exhibits a 7 σ deviation from the theoretical prediction [J. Ullmann et al., Nat. Commun. 8, 15484 (2017), 10.1038/ncomms15484; J. P. Karr, Nat. Phys. 13, 533 (2017), 10.1038/nphys4159]. We provide evidence that the discrepancy is caused by an inaccurate value of the tabulated nuclear magnetic moment (μI) of 209Bi. We perform relativistic density functional theory and relativistic coupled cluster calculations of the shielding constant that should be used to extract the value of μI(209ipts>) and combine it with nuclear magnetic resonance measurements of Bi (NO3 )3 in nitric acid solutions and of the hexafluoridobismuthate(V) BiF6- ion in acetonitrile. The result clearly reveals that μI(209Bi) is much smaller than the tabulated value used previously. Applying the new magnetic moment shifts the theoretical prediction into agreement with experiment and resolves the hyperfine puzzle.

  15. Vibrational Averaging of the Isotropic Hyperfine Coupling Constants for the Methyl Radical

    Science.gov (United States)

    Adam, Ahmad; Jensen, Per; Yachmenev, Andrey; Yurchenko, Sergei N.

    2014-06-01

    Electronic contributions to molecular properties are often considered as the major factor and usually reported in the literature without ro-vibrational corrections. However, there are many cases where the nuclear motion contributions are significant and even larger than the electronic contribution. In order to obtain accurate theoretical predictions, nuclear motion effects on molecular properties need to be taken into account. The computed isotropic hyperfine coupling constants for the nonvibrating methyl radical CH_3 are far from the experimental values. For CH_3, we have calculated the vibrational-state-dependence of the isotropic hyperfine coupling constant in the electronic ground state. The vibrational wavefunctions used in the averaging procedure were obtained variationally with the TROVE program. Analytical representations for the potential energy surfaces and the hyperfine coupling constant surfaces are obtained in least-squares fitting procedures. Thermal averaging has been carried out for molecules in thermal equilibrium, i.e., with Boltzmann-distributed populations. The calculation methods and the results will be discussed in detail.

  16. Biaxially textured articles formed by powder metallurgy

    Science.gov (United States)

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2003-07-29

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100} orientation texture; and further having a Curie temperature less than that of pure Ni.

  17. Comprehensive Wavelengths, Energy Levels, and Hyperfine Structure Parameters of Singly-Ionized Iron-Group Elements

    Science.gov (United States)

    Nave, Gillian

    We propose to measure wavelengths, energy levels, and hyperfine structure parameters of Ni II, Mn II, Sc II and other singly-ionized iron-group elements, covering the wavelength range 80 nm to 5500 nm. We shall use archival data from spectrometers at NIST and Kitt Peak National Observatory for spectra above 140 nm. Additional experimental observations will be taken if needed using Fourier transform spectrometers at NIST. Spectra will be taken using our normal incidence grating spectrograph to provide better sensitivity than the FT spectra and to extend the wavelength range down to 80 nm. We aim to produce a comprehensive description of the spectra of all singly-ionized iron- group elements. The wavelength uncertainty of the strong lines will be better than 1 part in 10^7. For most singly-ionized iron-group elements available laboratory data have uncertainties an order of magnitude larger than astronomical observations over wide spectra ranges. Some of these laboratory measurements date back to the 1960's. Since then, Fourier transform spectroscopy has made significant progress in improving the accuracy and quantity of data in the UV-vis-IR region, but high quality Fourier transform spectra are still needed for Mn II, Ni II and Sc II. Fourier transform spectroscopy has low sensitivity in the VUV region and is limited to wavelengths above 140 nm. Spectra measured with high-resolution grating spectrographs are needed in this region in order to obtain laboratory data of comparable quality to the STIS and COS spectrographs on the Hubble Space Telescope. Currently, such data exist only for Fe II and Cr II. Lines of Sc II, V II, and Mn II show hyperfine structure, but hyperfine structure parameters have been measured for relatively few lines of these elements. Significant errors can occur if hyperfine structure is neglected when abundances are determined from stellar spectra. Measurements of hyperfine structure parameters will be made using Fourier transform spectroscopy

  18. Surface modification of pharmaceutical powders

    OpenAIRE

    Zhou, Qi

    2017-01-01

    This thesis describes a body of work to investigate a mechanical dry powder coating approach aiming to modify the surface properties of fine pharmaceutical powders. Powders were coated with magnesium stearate (MgSt) in order to improve their bulk powder properties such as flowability, fluidization and aerosolization. The flow characteristics of a cohesive milled lactose monohydrate powder (Pharmatose® 450M, VMD around 20 μm) were substantially improved by processing with 1% w/w magn...

  19. Obtaining zircaloy powder through hydriding

    International Nuclear Information System (INIS)

    Dupim, Ivaldete da Silva; Moreira, Joao M.L.

    2009-01-01

    Zirconium alloys are good options for the metal matrix in dispersion fuels for power reactors due to their low thermal neutron absorption cross-section, good corrosion resistance, good mechanical strength and high thermal conductivity. A necessary step for obtaining such fuels is producing Zr alloy powder for the metal matrix composite material. This article presents results from the Zircaloy-4 hydrogenation tests with the purpose to embrittle the alloy as a first step for comminuting. Several hydrogenation tests were performed and studied through thermogravimetric analysis. They included H 2 pressures of 25 and 50 kPa and temperatures ranging between from 20 to 670 deg C. X-ray diffraction analysis showed in the hydrogenated samples the predominant presence of ZrH 2 and some ZrO 2 . Some kinetics parameters for the Zircaloy-4 hydrogenation reaction were obtained: the time required to reach the equilibrium state at the dwell temperature was about 100 minutes; the hydrogenation rate during the heating process from 20 to 670 deg C was about 21 mg/h, and at constant temperature of 670 deg C, the hydride rate was about 1.15 mg/h. The hydrogenation rate is largest during the heating process and most of it occurs during this period. After hydrogenated, the samples could easily be comminuted indicating that this is a possible technology to obtain Zircaloy powder. The results show that only few minutes of hydrogenation are necessary to reach the hydride levels required for comminuting the Zircaloy. The final hydride stoichiometry was between 2.7 and 2.8 H for each Zr atom in the sample (author)

  20. Recovery Of Electrodic Powder From Spent Lithium Ion Batteries (LIBs

    Directory of Open Access Journals (Sweden)

    Shin S.M.

    2015-06-01

    Full Text Available This study was focused on recycling process newly proposed to recover electrodic powder enriched in cobalt (Co and lithium (Li from spent lithium ion battery. In addition, this new process was designed to prevent explosion of batteries during thermal treatment under inert atmosphere. Spent lithium ion batteries (LIBs were heated over the range of 300°C to 600°C for 2 hours and each component was completely separated inside reactor after experiment. Electrodic powder was successfully recovered from bulk components containing several pieces of metals through sieving operation. The electrodic powder obtained was examined by X-ray diffraction (XRD, energy dispersive X-ray spectroscopy (EDS, and atomic absorption spectroscopy (AA and furthermore image of the powder was taken by scanning electron microscopy (SEM. It was finally found that cobalt and lithium were mainly recovered to about 49 wt.% and 4 wt.% in electrodic powder, respectively.

  1. Introduction to powder metallurgy processes for titanium manufacturing

    International Nuclear Information System (INIS)

    Esteban, P. G.; Bolzoni, L.; Ruiz-Navas, E. M.; Gordo, E.

    2011-01-01

    The development of new extraction processes to produce titanium in powder form leads Powder Metallurgy to an advantage position among the manufacturing processes for titanium. The cost reduction of base material, coupled with the economy of the powder metallurgy processes, give titanium industry the chance to diversify its products, which could lead to production volumes able to stabilise the price of the metal. This work reviews some of the Powder Metallurgy techniques for the manufacturing of titanium parts, and describes the two typical approaches for titanium manufacturing: Blending Elemental and Prealloyed Powders. Among others, conventional pressing and sintering are described, which are compared with cold and hot isostatic pressing techniques. Real and potential applications are described. (Author) 71 refs.

  2. Niobium powder synthesized by calciothermic reduction of niobium hydroxide for use in capacitors

    Science.gov (United States)

    Baba, Masahiko; Kikuchi, Tatsuya; Suzuki, Ryosuke O.

    2015-03-01

    Metallic niobium powder was produced for applications in electric capacitors via calciothermic reduction of niobium hydroxide in molten CaCl2. Sub-micrometer spherical metallic particles with coral-like morphologies reflected the particle size of the starting oxide powder. A fine powder was obtained from the mixtures of niobium hydroxide and CaO or Ca(OH)2, respectively. Sintered pellets of the metallic powder showed a higher capacitance (CV) than those of the simply reduced powder without pre-treatment, because the shrinkage during sintering was smaller. The CV was as large as that of commercially sintered pellets for tantalum capacitors. Therefore, this niobium powder would act as a higher-voltage capacitor by applying chemical anodic treatment at higher voltages, and lower oxygen content in the reduced power could realize a lower leak current.

  3. Hyperfine structure in 229gTh3+ as a probe of the 229gTh→ 229mTh nuclear excitation energy.

    Science.gov (United States)

    Beloy, K

    2014-02-14

    We identify a potential means to extract the 229gTh→ 229mTh nuclear excitation energy from precision microwave spectroscopy of the 5F(5/2,7/2) hyperfine manifolds in the ion 229gTh3+. The hyperfine interaction mixes this ground fine structure doublet with states of the nuclear isomer, introducing small but observable shifts to the hyperfine sublevels. We demonstrate how accurate atomic structure calculations may be combined with the measurement of the hyperfine intervals to quantify the effects of this mixing. Further knowledge of the magnetic dipole decay rate of the isomer, as recently reported, allows an indirect determination of the nuclear excitation energy.

  4. Spark plasma sintering of commercial and development titanium alloy powders

    OpenAIRE

    Weston, N.S.; Derguti, F.; Tudball, A.; Jackson, M.

    2015-01-01

    Emerging lower cost titanium metal powder produced via an electrolytic method has been fully consolidated using spark plasma sintering (SPS) generating microstructures comparable to those observed in Ti–6Al–4V PM product. This is the first time powder from an alternative titanium extraction method has been processed via SPS and it is benchmarked with commercial alloys (CP–Ti, Ti–6Al–4V, and Ti–5Al–5V–5Mo–3Cr). The effect of powder feedstock size, morphology, and alloy chemistry on the consoli...

  5. EPR spectrum of the Y@C82 metallofullerene isolated in solid argon matrix: hyperfine structure from EPR spectroscopy and relativistic DFT calculations.

    Science.gov (United States)

    Misochko, Eugenii Ya; Akimov, Alexander V; Belov, Vasilii A; Tyurin, Daniil A; Bubnov, Vyacheslav P; Kareev, Ivan E; Yagubskii, Eduard B

    2010-08-21

    The EPR spectrum of the Y@C(82) molecules isolated in solid argon matrix was recorded for the first time at a temperature of 5 K. The isotropic hyperfine coupling constant (hfcc) A(iso) = 0.12 +/- 0.02 mT on the nucleus (89)Y as derived from the EPR spectrum is found in more than two times greater than that obtained in previous EPR measurements in liquid solutions. Comparison of the measured hfcc on a metal atom with that predicted by density-functional theory calculations (PBE/L22) indicate that relativistic method provides good agreement between experiment in solid argon and theory. Analysis of the DFT calculated dipole-dipole hf-interaction tensor and electron spin distribution in the endometallofullerenes with encaged group 3 metal atoms Sc, Y and La has been performed. It shows that spin density on the scandium atom represents the Sc d(yz) orbital lying in the symmetry plane of the C(2v) fullerene isomer and interacting with two carbon atoms located in the para-position on the fullerene hexagon. In contrast, the configuration of electron spin density on the heavier atoms, Y and La, is associated with the hybridized orbital formed by interaction of the metal d(yz) and p(y) electronic orbitals.

  6. Hyperfine and magnetic properties of a Y{sub x}La{sub 1−x}FeO{sub 3} series (0 ≤ x ≤ 1)

    Energy Technology Data Exchange (ETDEWEB)

    Cristóbal, A.A.; Botta, P.M. [Instituto de Investigaciones en Ciencia y Tecnología de Materiales (INTEMA), CONICET-UNMdP, Av. J.B. Justo 4302, B7608FDQ Mar del Plata (Argentina); Bercoff, P.G., E-mail: bercoff@famaf.unc.edu.ar [Facultad de Matemática, Astronomía y Física (FaMAF), Universidad Nacional de Córdoba. IFEG (CONICET), Medina Allende s/n, Ciudad Universitaria, 5000 Córdoba (Argentina); Ramos, C.P. [CONICET and Centro Atómico Constituyentes (CAC), CNEA, Av. Gral. Paz 1499, 1650 San Martín (Argentina)

    2015-04-15

    Highlights: • Y{sub x}La{sub 1−x}FeO{sub 3} (0 ≤ x ≤ 1) was synthesized by mechanochemistry. • Two magnetic contributions were identified in the series. • A paramagnetic state is associated with a fraction of the smallest particles. • A ferromagnetic state is attributed to the larger particles. • Annealing of samples favored the formation of Y{sub 3}Fe{sub 5}O{sub 12} impurities. - Abstract: A series of orthoferrites Y{sub x}La{sub 1−x}FeO{sub 3} in the entire range of composition was synthesized at room temperature by mechanochemical activation of oxide mixtures. Phase composition, structure and microstructure of the obtained powder materials were characterized by X-ray diffraction and field-emission scanning electron microscopy. Hyperfine interactions and magnetic properties were determined by Mössbauer spectroscopy, SQUID and vibrating sample magnetometry. Two magnetic contributions could be identified in the series of materials: a paramagnetic state, associated with a fraction of the smallest particles and a ferromagnetic state, attributed to the larger particles. The results showed that the relative proportion of both contributions is very dependent on x, the Y content of samples. From M vs T measurements, it was possible to estimate the blocking temperature distribution for the end members of the series. Annealing of samples produced the elimination of the superparamagnetic behavior and the formation of Y{sub 3}Fe{sub 5}O{sub 12} impurities.

  7. Powder metallurgy development at SRL

    International Nuclear Information System (INIS)

    Peacock, H.B.

    1993-01-01

    The Savannah River Laboratory (SRL) is developing a powder metallurgy (P/M) process for manufacturing reactor-grade fuel tubes containing high wt % U 3 O 8 -Al cores clad with 8001 aluminum. The P/M cores are made by isostatic compaction. They are assembled in billets, outgassed, and hot-extruded using conventional coextrusion techniques. Cores have been compacted with up to 100% U3O 8 and tubes extruded with 80 wt % oxide cores. Irradiation tests have been made using P/M core tubes in the Savannah River reactors. These tubes contained U 3 O 8 concentrations up to 59 wt % and no significant swelling or blistering occurred. The tubes were irradiated to ∼ 40% burnup or 1.6x10 21 fissions/cc of core. This report discusses both small-scale and production tests for high-density P/M fuel development. The purpose of the P/M development program at SRL is to: determine the maximum U 3 O 8 content that can be fabricated into thin wall tubes, irradiate high-density tubes to high burnup and assess irradiation and dimensional stability, continue metal forming studies for extrusion and drawing, and evaluate hydrostatic extrusion and hydrostatically assisted drawing of P/M core tubes. Experimental results of testing the fuel assemblies performance so far indicate that: cores containing fine (-325 mesh) U 3 O 8 and aluminum powders can be made practically free of high-density areas using the outlined P/M pre blending and sieving techniques. U 3 O 8 -Al cores can be isostatically compacted with up to 100 wt U 3 O 8 and tubes successfully extruded with up to 80 wt oxide; fission gas blistering of U 3 O 8 -Al P/M tubes as indicated by the blister tests is a function of fissions/cc of U 3 O 8 in the core; Decreasing the fission density of oxide increases the threshold temperature for blister formation; U 3 O 8 -Al P/M fuel tubes with up to 59 wt U 3 O 8 have been successfully irradiated in SRP reactor to 1.6 x 10 21 fissions/cc of core or 7 x 10 20 fissions/cc of U 3 O 8 small

  8. Magnetically responsive enzyme powders

    Czech Academy of Sciences Publication Activity Database

    Pospišková, K.; Šafařík, Ivo

    2015-01-01

    Roč. 380, APR 2015 (2015), s. 197-200 ISSN 0304-8853 R&D Projects: GA MŠk(CZ) LD13021 Institutional support: RVO:67179843 Keywords : enzyme powders * cross-linking * magnetic modification * magnetic separation * magnetic iron oxides particles * microwave-assisted synthesis Subject RIV: CE - Biochemistry Impact factor: 2.357, year: 2015

  9. Laser cladding with powder

    NARCIS (Netherlands)

    Schneider, M.F.; Schneider, Marcel Fredrik

    1998-01-01

    This thesis is directed to laser cladding with powder and a CO2 laser as heat source. The laser beam intensity profile turned out to be an important pa6 Summary rameter in laser cladding. A numerical model was developed that allows the prediction of the surface temperature distribution that is

  10. Determination of the Mössbauer absorption cross section and reconstruction of hyperfine field distribution by the maximum entropy method.

    Science.gov (United States)

    Satuła, D; Szymański, K; Dobrzyński, L

    2010-07-28

    Determination of the Mössbauer absorption cross section, σ(E), and accurate reconstruction of the hyperfine field distributions of the invar alloy, Fe(64)Ni(36), by the maximum entropy method (MEM) is presented. The procedure consists of three steps: deconvolution of the Mössbauer spectra with the instrumental resolution function using MEM, nonlinear transformation of the deconvoluted spectrum into σ(E), and reconstruction of the hyperfine field distribution. In order to test the procedure of the deconvolution and correction for thickness effect, several simulated spectra with thickness parameter 1 invar alloy, measured with and without application of an external magnetic field, are discussed. The reconstruction has been made to test the earlier postulated non-collinear ferromagnetic state of invar without referring to any specific model in the analysis of the Mössbauer results. It is shown that marginal probability distribution of hyperfine magnetic field consists of the main maximum at about 28 T and a broad tail extending down to 5 T. Observed isomer shift of the main maximum is small and positive. The isomer shift decreases with magnetic field and attains negative values at the lowest fields. It is shown that the magnetic texture parameter does not depend on the hyperfine magnetic field. One thus concludes that in the invar Ni-Fe alloys, in contrast to some theoretical predictions, there is no evidence for different arrangements of the iron magnetic moments as a function of the magnetic hyperfine field.

  11. Ternary ceramic thermal spraying powder and method of manufacturing thermal sprayed coating using said powder

    Energy Technology Data Exchange (ETDEWEB)

    Vogli, Evelina; Sherman, Andrew J.; Glasgow, Curtis P.

    2018-02-06

    The invention describes a method for producing ternary and binary ceramic powders and their thermal spraying capable of manufacturing thermal sprayed coatings with superior properties. Powder contain at least 30% by weight ternary ceramic, at least 20% by weight binary molybdenum borides, at least one of the binary borides of Cr, Fe, Ni, W and Co and a maximum of 10% by weight of nano and submicro-sized boron nitride. The primary crystal phase of the manufactured thermal sprayed coatings from these powders is a ternary ceramic, while the secondary phases are binary ceramics. The coatings have extremely high resistance against corrosion of molten metal, extremely thermal shock resistance and superior tribological properties at low and at high temperatures.

  12. Blackbody radiation shift, multipole polarizabilities, oscillator strengths, lifetimes, hyperfine constants, and excitation energies in Hg+

    International Nuclear Information System (INIS)

    Simmons, M.; Safronova, M. S.; Safronova, U. I.

    2011-01-01

    Excitation energies of the [Xe]4f 14 5d 10 ns, [Xe]4f 14 5d 10 np j , [Xe]4f 14 5d 10 nd j , [Xe]4f 14 5d 10 n ' f j , and [Xe]4f 14 5d 10 n ' g j states in Hg + are evaluated (n≤10, n ' ≤9, and [Xe]=1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 5s 2 5p 6 ). First-, second-, third-, and all-order Coulomb energies and first- and second-order Coulomb-Breit energies are calculated. Reduced matrix elements, oscillator strengths, and transition rates are determined for electric-dipole transitions, including the ns (n=6-11), np (n=6-10), nd (n=6-10), nf (n=5-9), and ng (n=5-9) states. Lifetime values are determined for all above-mentioned states. The ground state E1, E2, and E3 polarizabilities are evaluated. The hyperfine structure in 199 Hg + and 201 Hg + ions is investigated. The hyperfine A and B values are determined for the first low-lying levels up to n = 7. The quadratic Stark effect on hyperfine structure levels of 199 Hg + and 201 Hg + ground states is investigated. The calculated shift for the 199 Hg + (F = 1, M = 0) ↔ (F = 0, M = 0) transition is -0.0597(2) Hz/(kV/cm) 2 , in agreement with previous theoretical result -0.060(3) Hz/(kV/cm) 2 . These calculations provide a theoretical benchmark for comparison with experiment and theory and provide values of blackbody radiation shifts for microwave frequency standards with 199 Hg + and 201 Hg + ions.

  13. Hyperfine interaction in the Autler-Townes effect: The formation of bright, dark, and chameleon states

    Science.gov (United States)

    Kirova, T.; Cinins, A.; Efimov, D. K.; Bruvelis, M.; Miculis, K.; Bezuglov, N. N.; Auzinsh, M.; Ryabtsev, I. I.; Ekers, A.

    2017-10-01

    This paper is devoted to clarifying the implications of hyperfine (HF) interaction in the formation of adiabatic (i.e., "laser-dressed") states and their expression in the Autler-Townes (AT) spectra. We first use the Morris-Shore model [J. R. Morris and B. W. Shore, Phys. Rev. A 27, 906 (1983), 10.1103/PhysRevA.27.906] to illustrate how bright and dark states are formed in a simple reference system where closely spaced energy levels are coupled to a single state with a strong laser field with the respective Rabi frequency ΩS. We then expand the simulations to realistic hyperfine level systems in Na atoms for a more general case when non-negligible HF interaction can be treated as a perturbation in the total system Hamiltonian. A numerical analysis of the adiabatic states that are formed by coupling of the 3 p3 /2 and 4 d5 /2 states by the strong laser field and probed by a weak laser field on the 3 s1 /2-3 p3 /2 transition yielded two important conclusions. Firstly, the perturbation introduced by the HF interaction leads to the observation of what we term "chameleon" states—states that change their appearance in the AT spectrum, behaving as bright states at small to moderate ΩS, and fading from the spectrum similarly to dark states when ΩS is much larger than the HF splitting of the 3 p3 /2 state. Secondly, excitation by the probe field from two different HF levels of the ground state allows one to address orthogonal sets of adiabatic states; this enables, with appropriate choice of ΩS and the involved quantum states, a selective excitation of otherwise unresolved hyperfine levels in excited electronic states.

  14. Transition metal complexes of neocryptolepine analogues. Part I: Synthesis, spectroscopic characterization, and invitro anticancer activity of copper(II) complexes

    Science.gov (United States)

    Emam, Sanaa Moustafa; El Sayed, Ibrahim El Tantawy; Nassar, Nagla

    2015-03-01

    New generation of copper(II) complexes with aminoalkylaminoneocryptolepine as bidentate ligands has been synthesized and it is characterized by elemental analyses, magnetic moment, spectra (IR, UV-Vis, 1H NMR and ESR) and thermal studies. The IR data suggest the coordination modes for ligands which behave as a bidentate with copper(II) ion. Based on the elemental analysis, magnetic studies, electronic and ESR data, binuclear square planar geometry was proposed for complexes 7a, 7b, square pyramidal for 9a, 9b and octahedral for 8a, 8b, 10a, 10b. The molar conductance in DMF solution indicates that all complexes are electrolyte except 7a and 7b. The ESR spectra of solid copper(II) complexes in powder form showed an axial symmetry with 2B1g as a ground state and hyperfine structure. The thermal stability and degradation of the ligands and their metal complexes were studied employing DTA and TG methods. The metal-free ligands and their copper(II) complexes were tested for their in vitro anticancer activity against human colon carcinoma (HT-29). The results showed that the synthesized copper(II) complexes exhibited higher anticancer activity than their free ligands. Of all the studied copper(II) complexes, the bromo-substituted complex 9b exhibited high anticancer activity at low micromolar inhibitory concentrations (IC50 = 0.58 μM), compared to the other complexes and the free ligands.

  15. Host material induced hyperfine structure of F{sup +} centres EPR spectra in CaS

    Energy Technology Data Exchange (ETDEWEB)

    Seeman, Viktor, E-mail: viktor.seeman@ut.ee; Dolgov, Sergei; Maaroos, Aarne

    2017-05-15

    The hyperfine structure (HFS) of F{sup +} centres in CaS single crystals due to the interaction with {sup 33}S and {sup 43}Ca nuclei was observed in EPR spectra for the first time. Angular variations of the HFS were measured for rotation of magnetic field in {100} and {110} crystallographic planes. Using measured orientation-dependent EPR spectra and the EPR NMR program, the parameters of the spin Hamiltonian were determined. In case of {sup 33}S nucleus there is a strong dependence of the F{sup +} centre EPR spectrum on the quadrupole term whereas for {sup 43}Ca nucleus this dependence is insignificant.

  16. Calculation of hyperfine constants for the H center in LiF

    International Nuclear Information System (INIS)

    Alencar, P.T.S.

    1975-01-01

    The EPR and the ENDOR hyperfine parameters for the H center in LiF are calculated assuming that the F - 2 central molecule is a simplified model for the electronic structure of this deffect. The best theoretical fitting was obtained by relaxing the ions neighboring the central molecule. We have obtained relaxations which are in agreement with the physical nature of this deffect, but for some ions the results have shown that a better wave functions for the unpaired electrons must be used. The results and the limitations of the suggested model, are discussed proposing a more realistic description for the deffect, than the F - 2 central molecule model

  17. Resolving spin-orbit- and hyperfine-mediated electric dipole spin resonance in a quantum dot.

    Science.gov (United States)

    Shafiei, M; Nowack, K C; Reichl, C; Wegscheider, W; Vandersypen, L M K

    2013-03-08

    We investigate the electric manipulation of a single-electron spin in a single gate-defined quantum dot. We observe that so-far neglected differences between the hyperfine- and spin-orbit-mediated electric dipole spin resonance conditions have important consequences at high magnetic fields. In experiments using adiabatic rapid passage to invert the electron spin, we observe an unusually wide and asymmetric response as a function of the magnetic field. Simulations support the interpretation of the line shape in terms of four different resonance conditions. These findings may lead to isotope-selective control of dynamic nuclear polarization in quantum dots.

  18. Variations of 57Fe hyperfine parameters in medicaments containing ferrous fumarate and ferrous sulfate

    International Nuclear Information System (INIS)

    Oshtrakh, M. I.; Novikov, E. G.; Dubiel, S. M.; Semionkin, V. A.

    2010-01-01

    Several commercially available medicaments containing ferrous fumarate (FeC 4 H 2 O 4 ) and ferrous sulfate (FeSO 4 ), as a source of ferrous iron, were studied using a high velocity resolution Mössbauer spectroscopy. A comparison of the 57 Fe hyperfine parameters revealed small variations for the main components in both medicaments indicating some differences in the ferrous fumarates and ferrous sulfates. It was also found that all spectra contained additional minor components probably related to ferrous and ferric impurities or to partially modified main components.

  19. Variations of {sup 57}Fe hyperfine parameters in medicaments containing ferrous fumarate and ferrous sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Oshtrakh, M. I., E-mail: oshtrakh@mail.utnet.ru; Novikov, E. G. [Ural Federal University (The former Ural State Technical University-UPI), Faculty of Physical Techniques and Devices for Quality Control (Russian Federation); Dubiel, S. M. [AGH University of Science and Technology, Faculty of Physics and Computer Science (Poland); Semionkin, V. A. [Ural Federal University (The former Ural State Technical University-UPI), Faculty of Physical Techniques and Devices for Quality Control (Russian Federation)

    2010-04-15

    Several commercially available medicaments containing ferrous fumarate (FeC{sub 4}H{sub 2}O{sub 4}) and ferrous sulfate (FeSO{sub 4}), as a source of ferrous iron, were studied using a high velocity resolution Moessbauer spectroscopy. A comparison of the {sup 57}Fe hyperfine parameters revealed small variations for the main components in both medicaments indicating some differences in the ferrous fumarates and ferrous sulfates. It was also found that all spectra contained additional minor components probably related to ferrous and ferric impurities or to partially modified main components.

  20. Analysis of structure of hyperfine poly(3-hydroxybutyrate) fibers (PHB) for controlled drug delivery

    Science.gov (United States)

    Olkhov, A. A.; Kosenko, R. Yu; Markin, V. S.; Zykova, A. K.; Pantyukhov, P. V.; Karpova, S. G.; Iordanskii, A. L.

    2017-12-01

    Hyperfine fibers based on biodegradable poly (3-hydroxybutyrate) with encapsulated drug substance (dipyridamol) were obtained by using electrospinning method. Addition of dipyridamol has a significant effect on geometrical shape and structure of microfibers as well as total porosity of fibrous material. Observation of fibers using scanning electron microscopy (SEM) method showed that without or at lower dipyridamol content (drug desorption from fibrous matrix was presented. In current work it was showed that the rate-limiting stage of transport was the diffusion of dipyridamol in the bulk of cylindrical fibers.

  1. Forward two-photon exchange in elastic lepton-proton scattering and hyperfine-splitting correction

    Energy Technology Data Exchange (ETDEWEB)

    Tomalak, Oleksandr [Johannes Gutenberg Universitaet, Institut fuer Kernphysik and PRISMA Cluster of Excellence, Mainz (Germany)

    2017-08-15

    We relate the forward two-photon exchange (TPE) amplitudes to integrals of the inclusive lepton-proton scattering cross sections. These relations yield an alternative way for the evaluation of the TPE correction to hyperfine-splitting (HFS) in the hydrogen-like atoms with an equivalent to the standard approach (Iddings, Drell and Sullivan) result implying the Burkhardt-Cottingham sum rule. For evaluation of the individual effects (e.g., elastic contribution) our approach yields a distinct result. We compare both methods numerically on examples of the elastic contribution and the full TPE correction to HFS in electronic and muonic hydrogen. (orig.)

  2. Comment on "Laser cooling of 173Yb for isotope separation and precision hyperfine spectroscopy"

    Science.gov (United States)

    McKnight, Quinton; Dodson, Adam; Sprenkle, Tucker; Bennett, Tyler; Bergeson, Scott

    2018-01-01

    We present measurements of the hyperfine splitting in the 173Yb 6 s 6 p P 1o1 (F'=3 /2 ,7 /2 ) states that disagree significantly with those measured previously by Das and Natarajan [Phys. Rev. A 76, 062505 (2007), 10.1103/PhysRevA.76.062505]. We point out inconsistencies in their measurements and suggest that their error is due to optical pumping and improper determination of the atomic line center. Our measurements are made using an optical frequency comb. We use an optical pumping scheme to improve the signal-to-background ratio for the F'=3 /2 component.

  3. Enhancement of surface integrity of titanium alloy with copper by means of laser metal deposition process

    CSIR Research Space (South Africa)

    Erinosho, MF

    2016-04-01

    Full Text Available The laser metal deposition process possesses the combination of metallic powder and laser beam respectively. However, these combinations create an adhesive bonding that permanently solidifies the laser-enhanced-deposited powders. Titanium alloys (Ti...

  4. Surface passivity largely governs the bioaccessibility of nickel-based powder particles at human exposure conditions.

    Science.gov (United States)

    Hedberg, Yolanda S; Herting, Gunilla; Latvala, Siiri; Elihn, Karine; Karlsson, Hanna L; Odnevall Wallinder, Inger

    2016-11-01

    The European chemical framework REACH requires that hazards and risks posed by chemicals, including alloys and metals, are identified and proven safe for humans and the environment. Therefore, differences in bioaccessibility in terms of released metals in synthetic biological fluids (different pH (1.5-7.4) and composition) that are relevant for different human exposure routes (inhalation, ingestion, and dermal contact) have been assessed for powder particles of an alloy containing high levels of nickel (Inconel 718, 57 wt% nickel). This powder is compared with the bioaccessibility of two nickel-containing stainless steel powders (AISI 316L, 10-12% nickel) and with powders representing their main pure alloy constituents: two nickel metal powders (100% nickel), two iron metal powders and two chromium metal powders. X-ray photoelectron spectroscopy, microscopy, light scattering, and nitrogen absorption were employed for the particle and surface oxide characterization. Atomic absorption spectroscopy was used to quantify released amounts of metals in solution. Cytotoxicity (Alamar blue assay) and DNA damage (comet assay) of the Inconel powder were assessed following exposure of the human lung cell line A549, as well as its ability to generate reactive oxygen species (DCFH-DA assay). Despite its high nickel content, the Inconel alloy powder did not release any significant amounts of metals and did not induce any toxic response. It is concluded, that this is related to the high surface passivity of the Inconel powder governed by its chromium-rich surface oxide. Read-across from the pure metal constituents is hence not recommended either for this or any other passive alloy. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

  5. Surface effects in metallic iron nanoparticles

    DEFF Research Database (Denmark)

    Bødker, Franz; Mørup, Steen; Linderoth, Søren

    1994-01-01

    Nanoparticles of metallic iron on carbon supports have been studied in situ by use of Mossbauer spectroscopy. The magnetic anisotropy energy constant increases with decreasing particle size, presumably because of the influence of surface anisotropy. Chemisorption of oxygen results in formation...... of a surface layer with magnetic hyperfine fields similar to those of thicker passivation layers, and with a ferromagnetic coupling to the spins in the core of the particles. In contrast, thicker passivation layers have a noncollinear spin structure....

  6. Low temperature spark plasma sintering of YIG powders

    International Nuclear Information System (INIS)

    Fernandez-Garcia, L.; Suarez, M.; Menendez, J.L.

    2010-01-01

    A transition from a low to a high spin state in the magnetization saturation between 1000 and 1100 o C calcination temperature is observed in YIG powders prepared by oxides mixture. Spark plasma sintering of these powders between 900 and 950 o C leads to dense samples with minimal formation of YFeO 3 , opening the way to co-sintering of YIG with metals or metallic alloys. The optical properties depend on the sintering stage: low (high) density samples show poor (bulk) optical absorption.

  7. Low temperature spark plasma sintering of YIG powders

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Garcia, L. [Department of Nanostructured Materials, Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN). Principado de Asturias - Consejo superior de Investigaciones Cientificas (CSIC) - Universidad de Oviedo - UO, Parque Tecnologico de Asturias, 33428 Llanera, Asturias (Spain); Suarez, M., E-mail: m.suarez@cinn.e [Department of Nanostructured Materials, Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN). Principado de Asturias - Consejo superior de Investigaciones Cientificas (CSIC) - Universidad de Oviedo - UO, Parque Tecnologico de Asturias, 33428 Llanera, Asturias (Spain); Fundacion ITMA, Parque Tecnologico de Asturias, 33428, Llanera (Spain); Menendez, J.L. [Department of Nanostructured Materials, Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN). Principado de Asturias - Consejo superior de Investigaciones Cientificas (CSIC) - Universidad de Oviedo - UO, Parque Tecnologico de Asturias, 33428 Llanera, Asturias (Spain)

    2010-07-16

    A transition from a low to a high spin state in the magnetization saturation between 1000 and 1100 {sup o}C calcination temperature is observed in YIG powders prepared by oxides mixture. Spark plasma sintering of these powders between 900 and 950 {sup o}C leads to dense samples with minimal formation of YFeO{sub 3}, opening the way to co-sintering of YIG with metals or metallic alloys. The optical properties depend on the sintering stage: low (high) density samples show poor (bulk) optical absorption.

  8. Mixing of the lowest-lying qqq configurations with JP =1/2‑ in different hyperfine interaction models

    Science.gov (United States)

    Chen, Jia; An, Chunsheng; Chen, Hong

    2018-02-01

    We investigate mixing of the lowest-lying qqq configurations with JP = 1/2‑ caused by the hyperfine interactions between quarks mediated by Goldstone Boson Exchange, One Gluon Exchange, and both Goldstone Boson and One Gluon exchange, respectively. The first orbitally excited nucleon, Σ, Λ and Ξ states are considered. Contributions of both the contact term and tensor term are taken into account. Our numerical results show that mixing of the studied configurations in the two employed hyperfine interaction models are very different. Therefore, the present results, which should affect the strong and electromagnetic decays of baryon resonances, may be used to examine the present employed hyperfine interaction models. Supported by National Natural Science Foundation of China (11675131,11645002), Chongqing Natural Science Foundation (cstc2015jcyjA00032) and Fundamental Research Funds for the Central Universities (SWU115020)

  9. Determination of the Moessbauer absorption cross section and reconstruction of hyperfine field distribution by the maximum entropy method

    Energy Technology Data Exchange (ETDEWEB)

    Satula, D; Szymanski, K; Dobrzynski, L, E-mail: satula@alpha.uwb.edu.p [Faculty of Physics, University of Bialystok, 41 Lipowa Street, 15-424 Bialystok (Poland)

    2010-07-28

    Determination of the Moessbauer absorption cross section, {sigma}(E), and accurate reconstruction of the hyperfine field distributions of the invar alloy, Fe{sub 64}Ni{sub 36}, by the maximum entropy method (MEM) is presented. The procedure consists of three steps: deconvolution of the Moessbauer spectra with the instrumental resolution function using MEM, nonlinear transformation of the deconvoluted spectrum into {sigma}(E), and reconstruction of the hyperfine field distribution. In order to test the procedure of the deconvolution and correction for thickness effect, several simulated spectra with thickness parameter 1 < t < 50 and different values of Lorentzian FWHM of the source and absorber were analyzed. It is shown that the procedure of the deconvolution and extraction of {sigma}(E) works well for spectra whose lines contain at least five experimental points per FWHM. Reconstructed distributions of hyperfine field parameters, based on the extracted Moessbauer cross section of the Fe-Ni invar alloy, measured with and without application of an external magnetic field, are discussed. The reconstruction has been made to test the earlier postulated non-collinear ferromagnetic state of invar without referring to any specific model in the analysis of the Moessbauer results. It is shown that marginal probability distribution of hyperfine magnetic field consists of the main maximum at about 28 T and a broad tail extending down to 5 T. Observed isomer shift of the main maximum is small and positive. The isomer shift decreases with magnetic field and attains negative values at the lowest fields. It is shown that the magnetic texture parameter does not depend on the hyperfine magnetic field. One thus concludes that in the invar Ni-Fe alloys, in contrast to some theoretical predictions, there is no evidence for different arrangements of the iron magnetic moments as a function of the magnetic hyperfine field.

  10. Investigation of hyperfine parameters of semiconductor oxides SnO{sub 2} and TiO{sub 2} pure and doped with 3d transition methods using spectroscopy of perturbed gamma-gamma angular correlation; Investigacao de parametros hiperfinos dos oxidos semicondutores SnO{sub 2} and TiO{sub 2} puros e dopados com metais de transicao 3d pela espectroscopia de correlacao angular gama-gama perturbada

    Energy Technology Data Exchange (ETDEWEB)

    Schell, Juliana

    2015-09-01

    This study aimed the use of nuclear technique Perturbed γ-γ Angular Correlation Spectroscopy (PAC) to measure the hyperfine interactions in thin films and powder samples of SnO{sub 2} and TiO{sub 2} pure and doped with transition metals to obtain a systematic investigation of defects and magnetism from an atomic point of view with the main motivation the application in spintronics. The work also focused on the preparation and characterization of samples by conventional techniques such as X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and magnetization measurements. Pure samples of the films were measured by the systematic variation of thermal treatment and applied magnetic field. These measurements were performed in HISKP at the University of Bonn (Rheinische Friedrich-Wilhelms-Universität Bonn) using {sup 111}In({sup 111}Cd) or {sup 181}Hf ({sup 181}Ta); at IPEN, in turn, these measurements were performed after the diffusion of the same probe nuclei. Another part of PAC measurements were carried out using {sup 111}mCd({sup 111}Cd) and {sup 117}Cd ({sup 117}In) in Isotope Mass Separator On-Line (ISOLDE) at Centre Européen Recherche Nucléaire (CERN). The measurements were performed from 8 K to 1173 K. After comparing results from macroscopic techniques with those from PAC, it was concluded that there is a correlation between the defects, magnetism and the mobility of charge carriers in semiconductors studied here. A step forward in the search for semiconductors, whose magnetic ordering allows its use in electronics based on spin. Some results have been published, including results obtained at the University of Bonn for the sandwich doctorate period [1-7]. (author)

  11. Helical magnetic structure and hyperfine interactions in FeP studied by {sup 57}Fe Mössbauer spectroscopy and {sup 31}P NMR

    Energy Technology Data Exchange (ETDEWEB)

    Sobolev, Alexey V., E-mail: alex@radio.chem.msu.ru [Department of Chemistry, Lomonosov Moscow State University, 119991, Moscow (Russian Federation); Presniakov, Igor A. [Department of Chemistry, Lomonosov Moscow State University, 119991, Moscow (Russian Federation); Gippius, Andrey A. [Department of Physics, Lomonosov Moscow State University, 119991, Moscow (Russian Federation); Experimental Physics V, University of Augsburg, 86159, Augsburg (Germany); Chernyavskii, Ivan V. [Department of Chemistry, Lomonosov Moscow State University, 119991, Moscow (Russian Federation); Schaedler, Martina; Buettgen, Norbert [Experimental Physics V, University of Augsburg, 86159, Augsburg (Germany); Ibragimov, Sergey A.; Morozov, Igor V.; Shevelkov, Andrei V. [Department of Chemistry, Lomonosov Moscow State University, 119991, Moscow (Russian Federation)

    2016-08-05

    We report results of {sup 57}Fe Mössbauer and {sup 31}P NMR studies of a phosphide FeP powder sample performed in a wide temperature range including the point (T{sub N} ≈ 120 K) of magnetic phase transitions. The {sup 57}Fe Mössbauer spectra at low temperatures T < T{sub N} present a very complex Zeeman pattern with line broadenings and sizeable spectral asymmetry. It was shown that the change of the observed spectral shape is consistent with the transition into a space-modulated helicoidal magnetic structure. Analysis of the experimental spectra was carried out assuming an anisotropy of the magnetic hyperfine field H{sub hf} at the {sup 57}Fe nuclei when the Fe{sup 3+} magnetic moment rotates with respect to the principal axis of the electric field gradient (EFG) tensor. The obtained large temperature independent anharmonicity parameter m ≈ 0.96 of the helicoidal spin structure results from easy-axis anisotropy in the plane of the iron spin rotation. It was assumed that a very low maximal value of H{sub hf}(11 K) ≈ 36 kOe and its high anisotropy ΔH{sub anis}(11 K) ≈ 30 kOe can be attributed to the stabilization of iron cations in the low-spin state (S{sub Fe} = 1/2). The {sup 31}P NMR measurements demonstrate an extremely broad linewidth reflecting the spatial distribution of the transferred internal magnetic fields of the Fe{sup 3+} ions onto P sites in the magnetically ordered state. - Highlights: • The {sup 57}Fe Mössbauer and {sup 31}P NMR studies of FeP in a wide temperature range. • Anharmonicity of helicoidal magnetic structure results from easy-axis anisotropy. • The spatial distribution of the transferred magnetic fields of the Fe{sup 3+} ions onto P sites. • Mechanisms of the anisotropy of the magnetic hyperfine field H{sub hf} at the {sup 57}Fe nuclei.

  12. Hyperfine interactions and some thermomagnetic properties of amorphous FeZr(CrNbBCu alloys

    Directory of Open Access Journals (Sweden)

    Łukiewska Agnieszka

    2017-06-01

    Full Text Available In this research, we studied the magnetic phase transition by Mössbauer spectroscopy and using vibrating sample magnetometer for amorphous Fe86-xZr7CrxNb2Cu1B4 (x = 0 or 6 alloys in the as-quenched state and after accumulative annealing in the temperature range 600-750 K. The Mössbauer investigations were carried out at room and nitrogen temperatures. The Mössbauer spectra of the investigated alloys at room temperature are characteristic of amorphous paramagnets and have a form of asymmetric doublets. However, at nitrogen temperature, the alloys behave like ferromagnetic amorphous materials. The two components are distinguished in the spectrum recorded at both room and nitrogen temperatures. The low field component in the distribution of hyperfine field induction shifts towards higher field with the annealing temperature. It is assumed that during annealing at higher temperature, due to diffusion processes, the grains of α-Fe are created in the area corresponding to this component. Both investigated alloys show the invar effect and the decrease of hyperfine field induction after annealing at 600 K for 10 min is observed. It is accompanied by the lowering of Curie temperature.

  13. Effects of variation of hyperfine splitting(structure) in atomic physics

    International Nuclear Information System (INIS)

    Alavi, S A

    2009-01-01

    The possible variation of the fundamental constants is currently a very popular research topic. Theories unifying gravity and other interactions suggest the possibility of spatial and temporal variation of physics constants in the universe. Current interest is high because in superstring theories which have additional dimensions compactified on tiny scales any variation of the size of the extra dimensions results in changes in the 3-dimensional coupling constants. String theory also suggest the space to be noncommutative i.e., the space coordinates do not commute with each other. In this paper we study the hyperfine splitting in the framework of the noncommutative quantum mechanics(NCQM) developed in the literature. We show that the energy difference between two excited F = I + 1/2 and the ground F I - 1/2 states in a noncommutative space(NCS) is bigger than the one in commutative case, so the radiation wavelength in NCS s must be shorter than the radiation wavelength in commutative spaces. We also find an upper bound for the non-commutativity parameter. Since in the very tiny string scale or at very high energy situation the effects of non-commutativity of space may appear so the hyperfine splitting is not constant and changes as energy changes(high energy situation). The results would be of interest both for theoretical and optical spectroscopists.

  14. Hyperfine splitting in simple ions for the search of the variation of fundamental constants

    Science.gov (United States)

    Oreshkina, Natalia S.; Cavaletto, Stefano M.; Michel, Niklas; Harman, Zoltán; Keitel, Christoph H.

    2017-09-01

    Numerous few-electron atomic systems are considered which can be used effectively for observing a potential variation of the fine-structure constant α and the electron-proton mass ratio me/mp . We examine optical magnetic dipole transitions between hyperfine-structure components in heavy highly charged H-like and Li-like ions with observably high sensitivity to a variation of α and me/mp . The experimental spectra of the proposed systems consist of a strong single line, which simplifies significantly the data analysis and shortens the necessary measurement time. Furthermore, we propose systems for an experimental test of the variation of quark masses and discuss the expected level of accuracy in assessing its limitations. Finally, we establish which constraints on the variation of these fundamental constants could be provided by measurements with a hyperfine-structure highly-charged-ion clock and some reference clock, showing that a significant improvement of the current limitations can be reached.

  15. Hyperfine characterization of SrTixHf1-xO3

    International Nuclear Information System (INIS)

    Alonso, Roberto E.; Falabella, Martin; Lopez-Garcia, Alberto R.

    2007-01-01

    In order to study how the Hf replacement by Ti affects the crystalline structure of SrHfO 3 pure perovskite, X-ray diffraction (XRD) studies and hyperfine characterizations of SrHf 1-x Ti x O 3 for the compositions x=0.25, 0.50 and 0.75 are reported. The structure at room temperature (RT) was determined by XRD. Hyperfine electric quadrupole interaction at Ta probes was determined by perturbed angular correlation spectroscopy. For every sample, spin precession curves were measured from RT to 1000deg. C , in 50deg. C steps. From the data fit it was determined that for x=0.25 the compound is orthorhombic (Pnma) at RT and undergoes one first-order and one second-order phase transitions at 550 and 750deg. C , respectively. For x=0.50 the compound is in the orthorhombic (Cmcm) phase at RT and undergoes a second-order phase transition at about 250deg. C . For x=0.75, the compound is cubic (Pm3-bar m) from RT on. Also, comparison with other perovskite-type compound studies is performed

  16. Electron-impact rotational and hyperfine excitation of HCN, HNC, DCN and DNC

    Science.gov (United States)

    Faure, Alexandre; Varambhia, Hemal N.; Stoecklin, Thierry; Tennyson, Jonathan

    2007-12-01

    Rotational excitation of isotopologues of HCN and HNC by thermal electron-impact is studied using the molecular R-matrix method combined with the adiabatic-nuclei-rotation approximation. Rate coefficients are obtained for electron temperatures in the range 5-6000 K and for transitions among all levels up to J = 8. Hyperfine rates are also derived using the infinite-order-sudden scaling method. It is shown that the dominant rotational transitions are dipole-allowed, that is, those for which ΔJ = 1. The hyperfine propensity rule ΔJ = ΔF is found to be stronger than that in the case of He-HCN collisions. For dipole-allowed transitions, electron-impact rates are shown to exceed those for excitation of HCN by He atoms by six orders of magnitude. As a result, the present rates should be included in any detailed population model of isotopologues of HCN and HNC in sources where the electron fraction is larger than 10-6, for example, in interstellar shocks and comets.

  17. Sign determination of the hyperfine field by elliptically polarized Moessbauer source

    Energy Technology Data Exchange (ETDEWEB)

    Tancziko, F., E-mail: tancziko@rmki.kfki.hu; Bottyan, L.; Deak, L.; Merkel, D. G.; Nagy, D. L. [KFKI Research Institute for Particle and Nuclear Physics (Hungary)

    2009-01-15

    A novel approach of determining the sign of the hyperfine magnetic field using elliptically polarized resonant {gamma}-photons is presented. The method is demonstrated by a transmission experiment on {alpha}-Fe using a {sup 57}Co:{alpha}-Fe source partially saturated parallel and antiparallel to each other in plane at a shallow angle of {approx}10{sup o} relative to the k-vector of the {gamma}-rays. The evaluation procedure decomposes the resulting spectra into four linearly independent principal subspectra, namely I{sub ||} , I{sub perpendicular}, I{sub {up_arrow}{up_arrow}}, I{sub {up_arrow}{down_arrow}}, the linearly polarized parallel and perpendicular as well as the circularly polarized parallel and antiparallel components, respectively, and derives the experimental average polar angles of the hyperfine fields both in the source and absorber {alpha}-Fe foils as well as the mean difference of the azimuth angles. By this procedure not only the relative alignment but also the relative sign is determined.

  18. Dispersing powders in liquids

    CERN Document Server

    Nelson, RD

    1988-01-01

    This book provides powder technologists with laboratory procedures for selecting dispersing agents and preparing stable dispersions that can then be used in particle size characterization instruments. Its broader goal is to introduce industrial chemists and engineers to the phenomena, terminology, physical principles, and chemical considerations involved in preparing and handling dispersions on a commercial scale. The book introduces novices to: - industrial problems due to improper degree of dispersion; - the nomenclature used in describing particles; - the basic physica

  19. Searching for an oscillating massive scalar field as a dark matter candidate using atomic hyperfine frequency comparisons

    OpenAIRE

    Hees, A.; Guéna, J.; Abgrall, M.; Bize, S.; Wolf, P.

    2016-01-01

    We use six years of accurate hyperfine frequency comparison data of the dual rubidium and caesium cold atom fountain FO2 at LNE-SYRTE to search for a massive scalar dark matter candidate. Such a scalar field can induce harmonic variations of the fine structure constant, of the mass of fermions and of the quantum chromodynamic mass scale, which will directly impact the rubidium/caesium hyperfine transition frequency ratio. We find no signal consistent with a scalar dark matter candidate but pr...

  20. Hyperfine structure of 147,149Sm measured using saturated absorption spectroscopy in combination with resonance-ionization mass spectroscopy

    International Nuclear Information System (INIS)

    Park, Hyunmin; Lee, Miran; Rhee, Yongjoo

    2003-01-01

    The hyperfine structures of four levels of the Sm isotopes have been measured by means of diode-laser-based Doppler-free saturated absorption spectroscopy in combination with a diode-laser-initiated resonance-ionization mass spectroscopy. It was demonstrated that combining the two spectroscopic methods was very effective for the identification and accurate measurement of the spectral lines of atoms with several isotopes, such as the rare-earth elements. From the obtained spectra, the hyperfine constants A and B for the odd-mass isotopes 147 Sm and 149 Sm were determined for four upper levels of the studied transitions.

  1. Bi donor hyperfine state populations studied by optical transitions of donor bound excitons in enriched {sup 28}Si

    Energy Technology Data Exchange (ETDEWEB)

    Ilkhchy, K. Saeedi; Steger, M.; Thewalt, M. L. W. [Department of Physics, Simon Fraser University, Burnaby, BC V5A 1S6 (Canada); Abrosimov, N.; Riemann, H. [Leibniz-Institut für Kristallzüchtung, 12489 Berlin (Germany); Becker, P. [PTB Braunschweig, 38116 Braunschweig (Germany); Pohl, H.-J. [Vitcon Projectconsult GmbH, 07745 Jena (Germany)

    2013-12-04

    We report on the first optical studies of Bi donor bound excitons in {sup 28}Si, using absorption rather than emission spectroscopy, and a new noncontact photoconductivity method which has much higher sensitivity and spectral resolution than photoluminescence spectroscopy. Individual hyperfine components of this potential semiconductor qubit can be resolved under an applied magnetic field, and we find that strong nonresonant optical hyperpolarization towards both the I{sub z} = +9/2 and −9/2 hyperfine states can be observed, depending on the intensity of the above-gap excitation.

  2. Mixed hyperfine interaction in amorphous Fe-Zr sputtered films in external magnetic field - a 57Fe Moessbauer study

    International Nuclear Information System (INIS)

    Fries, S.M.; Crummenauer, J.; Wagner, H.-G.; Gonser, U.; Chien, C.L.

    1986-01-01

    Conventional 57 Fe-Moessbauer spectroscopy provides only information about the magnitude of the splitting QS in the case of electric quadrupole hyperfine interaction, but not on the sign of the main component of the electric field gradient (EFG) or the asymmetry parameter which are sensitive to the local environment of the 57 Fe nuclei. This kind of information is obtained by measurements in external magnetic fields. In the case of amorphous Fe-Zr sputtered films mixed hyperfine interaction leads to a clear change in the behaviour of the Zr-rich and the Fe-rich alloys, indicating the existence of magnetic clusters in the Fe-rich samples. (Auth.)

  3. Construction of the energy matrix for complex atoms. Part VIII: Hyperfine structure HPC calculations for terbium atom

    Science.gov (United States)

    Elantkowska, Magdalena; Ruczkowski, Jarosław; Sikorski, Andrzej; Dembczyński, Jerzy

    2017-11-01

    A parametric analysis of the hyperfine structure (hfs) for the even parity configurations of atomic terbium (Tb I) is presented in this work. We introduce the complete set of 4fN-core states in our high-performance computing (HPC) calculations. For calculations of the huge hyperfine structure matrix, requiring approximately 5000 hours when run on a single CPU, we propose the methods utilizing a personal computer cluster or, alternatively a cluster of Microsoft Azure virtual machines (VM). These methods give a factor 12 performance boost, enabling the calculations to complete in an acceptable time.

  4. Structure and Properties of Nanocrystalline Oxide Powders

    Science.gov (United States)

    Ulyanova, T. M.; Krut'ko, N. P.; Titova, L. V.; Medichenko, S. V.

    2005-11-01

    The crystalline and porous structure of superfine powders and fibers made of alumina and zirconia doped with yttria is investigated. The particle sizes were determined by the methods of coherent dispersion and scanning transmission electron microscopy. Based on data on the sizes of crystallites of the metal oxides, which were obtained by different methods, it is found that crystalline transformations of the oxides lead to dispersion of the materials. The structural transformations of the superfine oxides are accompanied by changes in crystallite sizes and in the character and size of pores. The laws established allow one to purposefully control the process of producing nanostructured oxide powders and fibers, which can be utilized as active fillers for composite materials based on various matrices.

  5. Development of Pneumatic Transport System (PTS) for safe handling of uranium oxide powder in UMP/UED

    International Nuclear Information System (INIS)

    Manna, S.; Satpati, S.K.; Roy, S.B.

    2009-01-01

    Tonnage quantity radioactive uranium oxide powder of particle size sub micron to 100 micron is handled in Uranium Metal Plant (UMP), UED/BARC for production of nuclear grade uranium metal, required for fuelling research reactors - Dhruva and Cirus. A Pneumatic Transfer System (PTS) using vacuum has been introduced and is being used for handling radioactive powder to improve radiation protection

  6. Processing of alumina and zirconia nano-powders and compacts

    Energy Technology Data Exchange (ETDEWEB)

    Wu Yujie; Bandyopadhyay, Amit; Bose, Susmita

    2004-08-25

    Magnesia-doped alumina and yttria-doped zirconia nano-powders were synthesized using sucrose as a chelating agent and template material from the aqueous solutions of aluminium nitrate, magnesium nitrate, ytrrium nitrate and zirconyl nitrate, respectively. Synthesis parameters were optimized with varying sucrose to metal ion ratio, calcinations time, and temperature to produce these nano-powders. As-synthesized powders were characterized by room temperature X-ray diffraction, BET surface area analyzer and transmission electron microscopy. Y{sub 2}O{sub 3}-ZrO{sub 2} nano-powders had particle size in the range of 80-200 nm with specific average surface area of 119 m{sup 2}/g and for MgO-Al{sub 2}O{sub 3} powders, particle sizes were 30-200 nm with the specific average surface area of 250 m{sup 2}/g. Our results indicate that this synthesis method is a versatile one and can be applied to a variety of oxide-based materials to form nano-powders. Nano-powders were compacted uniaxially and densified in a muffle furnace. Sintered discs were used for hardness testing and density measurements, as well as for microstructural characterization.

  7. Influence of small particles inclusion on selective laser melting of Ti-6Al-4V powder

    Science.gov (United States)

    Gong, Haijun; Dilip, J. J. S.; Yang, Li; Teng, Chong; Stucker, Brent

    2017-12-01

    The particle size distribution and powder morphology of metallic powders have an important effect on powder bed fusion based additive manufacturing processes, such as selective laser melting (SLM). The process development and parameter optimization require a fundamental understanding of the influence of powder on SLM. This study introduces a pre-alloyed titanium alloy Ti-6Al-4V powder, which has a certain amount of small particles, for SLM. The influence of small particle inclusion is investigated through microscopy of surface topography, elemental and microstructural analysis, and mechanical testing, compared to the Ti-6Al-4V powder provided by SLM machine vendor. It is found that the small particles inclusion in Ti-6Al-4V powder has a noticeable effect on extra laser energy absorption, which may develop imperfections and deteriorate the SLM fatigue performance.

  8. Powder metallurgy development at SRL

    International Nuclear Information System (INIS)

    Peacock, H.B.

    1993-01-01

    The Savannah River Laboratory (SRL) is developing a powder metallury (P/M) process for manufacturing reactor-grade fuel tubes containing high wt % U 3 O 8 -Al cores clad with 8001 aluminum. The P/M cores are made by isostatic compaction. They are assembled in billets, outgassed, and hot-extruded using conventional coextrusion techniques. Cores have been compacted with up to 100% U 3 O 8 and tubes extruded with 80 wt % oxide cores. Irradiation tests have been made using P/M core tubes in the Savannah River reactors. These tubes contained U 3 O 8 concentrations up to 59 wt % and no significant swelling or blistering occurred. The tubes were irradiated to ∼40% burnup or 1.6x10 21 fissions/cc of core. This report discusses both small-scale and production tests for high- density P/M fuel development. The purpose of the P/M development program at SRL is to: (1) determine the maximum U 3 O 8 content that can be fabricated into thin wall tubes, (2) irradiate high-density tubes to high burnup and assess irradiation and dimensional stability, (3) continue metal forming studies for extrusion and drawing, and (4) evaluate hydrostatic extrusion and hydrostatically assisted drawing of P/M core tubes

  9. Effect of interfacial friction during forging of solid powder discs of ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Effect of interfacial friction during forging of solid powder ... deformation. Hence, friction in plastic deformation is essentially different from sliding friction in machine parts. Direct metal-to-metal contact between the die and the ..... Rooks B W 1974 The effect of die temperature on metal flow and die wear during high speed hot.

  10. Powder metallurgical high performance materials. Proceedings. Volume 3: general topics

    International Nuclear Information System (INIS)

    Kneringer, G.; Roedhammer, P.; Wildner, H.

    2001-01-01

    The proceedings of these seminars form an impressive chronicle of the continued progress in the understanding of refractory metals and cemented carbides and in their manufacture and application. The 15 th Plansee Seminar was convened under the general theme 'Powder Metallurgy High Performance Materials'. Under this broadened perspective the seminar will strive to look beyond the refractory metals and cemented carbides, which remain at its focus, to novel classes of materials, such as intermetallic compounds, with potential for high temperature applications. (boteke)

  11. Diffraction. Powder, amorphous, liquid

    International Nuclear Information System (INIS)

    Sosnowska, I.M.

    1999-01-01

    Neutron powder diffraction is a unique tool to observe all possible diffraction effects appearing in crystal. High-resolution neutron diffractometers have to be used in this study. Analysis of the magnetic structure of polycrystalline materials requires the use of high-resolution neutron diffraction in the range of large interplanar distances. As distinguished from the double axis diffractometers (DAS), which show high resolution only at small interplanar distances, TOF (time-of-flight) diffractometry offers the best resolution at large interplanar distances. (K.A.)

  12. Structural, electronic, and hyperfine properties of pure and Ta-doped m-ZrO2

    DEFF Research Database (Denmark)

    Taylor, M.A.; Alonso, R.E.; Errico, L.A.

    2012-01-01

    A combination of experiments and ab initio quantum-mechanical calculations has been applied to examine electronic, structural, and hyperfine interactions in pure and Ta-doped zirconium dioxide in its monoclinic phase (m-ZrO2). From the theoretical point of view, the full-potential linear augmente...

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

    DEFF Research Database (Denmark)

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

    1978-01-01

    The isotropic and anisotropic transferred hyperfine interactions between F ions in the two chemically inequivalent sites and the rare-earth ions (R) have been derived from 19F NMR measurements in the temperature region 100-300 K on single crystals of TbF3 and DyF3. The isotropic interactions are ...

  14. Rotational spectra, nuclear quadrupole hyperfine tensors, and conformational structures of the mustard gas simulent 2-chloroethyl ethyl sulfide

    Science.gov (United States)

    Tubergen, M. J.; Lesarri, A.; Suenram, R. D.; Samuels, A. C.; Jensen, J. O.; Ellzy, M. W.; Lochner, J. M.

    2005-10-01

    Rotational spectra have been recorded for both the 35Cl and 37Cl isotopic forms of two structural conformations of 2-chloroethyl ethyl sulfide (CEES). The rotational constants of the 35Cl and 37Cl isotopomers were used to identify the conformational isomers. A total of 236 hyperfine transitions have been assigned for 47 rotational transitions of the 35Cl isotope of a GGT conformer, and 146 hyperfine have been assigned for 37 rotational transitions of the 37Cl isotopomer. For the second conformer, a total of 128 (110) hyperfine and 30 (28) rotational transitions have also been assigned to the 35Cl ( 37Cl) isotopes of a TGT conformation. The extensive hyperfine splitting data, measured to high resolution with a compact Fourier transform microwave spectrometer, were used to determine both the diagonal and off-diagonal elements of the 35Cl and 37Cl nuclear quadrupole coupling tensors in the inertial tensor principal axis system. The experimental rotational constant data, as well as the 35Cl and 37Cl nuclear quadrupole coupling tensors, were compared to the results from 27 optimized ab initio (HF/6-311++G ∗∗ and MP2/6-311++G ∗∗) model structures.

  15. Hyperfine fields of Fe in Nd2Fe14BandSm2Fe17N3

    Science.gov (United States)

    Akai, Hisazumi; Ogura, Masako

    2015-03-01

    High saturation magnetization of rare-earth magnets originates from Fe and the strong magnetic anisotropy stems from f-states of rare-earth elements such as Nd and Sm. Therefore the hyperfine fields of both Fe and rare-earth provide us with important pieces of information: Fe NMR enable us to detect site dependence of the local magnetic moment and magnetic anisotropy (Fe sites also contribute to the magnetic anisotropy) while rare-earth NQR directly give the information of electric field gradients (EFG) that are related to the shape of the f-electron cloud as well as the EFG produced by ligands. In this study we focus on the hyperfine fields of materials used as permanent magnets, Nd2Fe14BandSm2Fe17N3 from theoretical points of view. The detailed electronic structure together with the hyperfine interactions are discussed on the basis of the first-principles calculation. In particular, the relations between the observed hyperfine fields and the magnetic properties are studies in detail. The effects of doping of those materials by other elements such as Dy and the effects of N adding in Sm2Fe17N3 will be discussed. This work was supported by Elements Strategy Initiative Center for Magnetic Materials Project, the Ministry of Education, Culture, Sports, Science and Technology, Japan.

  16. Calculation of the hyperfine structure transition energy and lifetime in the one-electron Bi[sup 82+] ion

    Energy Technology Data Exchange (ETDEWEB)

    Finkbeiner, M. (Fachbereich Physik, Univ. Kassel (Germany)); Fricke, B. (Fachbereich Physik, Univ. Kassel (Germany)); Kuehl, T. (GSI, Darmstadt (Germany))

    1993-05-03

    We calculate the energy and lifetime of the ground state hyperfine structure transition in one-electron Bi[sup 82+]. The influence of various distributions of the magnetic moment and the electric charge in the nucleus [sub 83][sup 209]Bi on energy and lifetime is studied. (orig.)

  17. Hyperfine interactions in soybean and lupin oxy-leghemoglobins studied using Mössbauer spectroscopy with a high velocity resolution

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, A. [University of Delhi South Campus, Department of Biochemistry (India); Alenkina, I. V. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation); Zakharova, A. P. [Ural Federal University, Department of Experimental Physics, Institute of Physics and Technology (Russian Federation); Oshtrakh, M. I., E-mail: oshtrakh@gmail.com; Semionkin, V. A. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation)

    2015-04-15

    A comparative study of monomeric soybean and lupin leghemoglobins in the oxy-form was carried out using Mössbauer spectroscopy with a high velocity resolution at 90 K. The {sup 57}Fe hyperfine parameters of measured spectra were evaluated and compared with possible structural differences in the heme Fe(II)–O {sub 2} bond.

  18. Characteristics of Inconel Powders for Powder-Bed Additive Manufacturing

    OpenAIRE

    Quy Bau Nguyen; Mui Ling Sharon Nai; Zhiguang Zhu; Chen-Nan Sun; Jun Wei; Wei Zhou

    2017-01-01

    In this study, the flow characteristics and behaviors of virgin and recycled Inconel powder for powder-bed additive manufacturing (AM) were studied using different powder characterization techniques. The results revealed that the particle size distribution (PSD) for the selective laser melting (SLM) process is typically in the range from 15 μm to 63 μm. The flow rate of virgin Inconel powder is around 28 s·(50 g)−1. In addition, the packing density was found to be 60%. The rheological test re...

  19. Oxidizability and explosibility of pure graphite powder

    International Nuclear Information System (INIS)

    L Rahmani; D Roubineau; S Cornet

    2005-01-01

    Full text of publication follows: While graphite is widely considered a heat-resistant material, e.g. able to screen metallic shielding from thermal damage, and graphite powder is used as a fire extinguisher agent where water or carbon dioxide should not, it still can react with air and - being carbon - give forth a significant amount of heat. Whether this makes it a hazard in operations such as dismantling nuclear reactors that contain hundreds of tons of graphite, including a small percentage of powder, is a question that has to be answered, considering that dismantling implies the use of such potential fire initiators as thermal cutters and electrical equipment. For this reason EDF commissioned the Centre National de Prevention et Protection (CNPP) to carry out explosibility tests on unirradiated, nuclear grade (i.e. with about 100 ppm of impurities) graphite powder. CNPP tests were so designed as to simulate realistic conditions that might result from a severe mishap during a dismantling operation, such as the crash of heavy equipment on graphite blocks coupled with the bruise of a high power electrical cable. EDF-CNPP tests complement others, done either in Italy most notably on irradiated graphite dust contaminated with various pollutants, or in the UK where the ability of settled graphite dust to propagate an initial gas explosion into an adjacent volume was assessed. EDF-CNPP tests comprise two steps. Step one was intended to produce a qualitative understanding of how nuclear grade graphite behaves while heated in air. In a first series of experiments graphite samples were heated up to 900 C during two and a half hours and their mass loss measured: it was found that while fine powder is wholly oxidised, coarser powder and chunks retained about two thirds of their initial mass. Oxidation kinetics, as assessed by oven temperature shoot-up, begins at 580 C and is quite low, compared with that of iron powder. In a second series of experiments a graphite piece

  20. Oxidizability and explosibility of pure graphite powder

    International Nuclear Information System (INIS)

    Rahmani, L.; Roubineau, D.; Cornet, S.

    2005-01-01

    Full text of publication follows: While graphite is widely considered a heat-resistant material, e.g. able to screen metallic shielding from thermal damage, and graphite powder is used as a fire extinguisher agent where water or carbon dioxide should not, it still can react with air and - being carbon - give forth a significant amount of heat. Whether this makes it a hazard in operations such as dismantling nuclear reactors that contain hundreds of tons of graphite, including a small percentage of powder, is a question that has to be answered, considering that dismantling implies the use of such potential fire initiators as thermal cutters and electrical equipment. For this reason EDF commissioned the Centre National de Prevention et Protection (CNPP) to carry out explosibility tests on unirradiated, nuclear grade (i.e. with about 100 ppm of impurities) graphite powder. CNPP tests were so designed as to simulate realistic conditions that might result from a severe mishap during a dismantling operation, such as the crash of heavy equipment on graphite blocks coupled with the bruise of a high power electrical cable. EDF-CNPP tests complement others, done either in Italy most notably on irradiated graphite dust contaminated with various pollutants, or in the UK where the ability of settled graphite dust to propagate an initial gas explosion into an adjacent volume was assessed. EDF-CNPP tests comprise two steps. Step one was intended to produce a qualitative understanding of how nuclear grade graphite behaves while heated in air. In a first series of experiments graphite samples were heated up to 900 C during two and a half hours and their mass loss measured: it was found that while fine powder is wholly oxidised, coarser powder and chunks retained about two thirds of their initial mass. Oxidation kinetics, as assessed by oven temperature shoot-up, begins at 580 C and is quite low, compared with that of iron powder. In a second series of experiments a graphite piece

  1. Multi-objective parametric optimization of powder mixed electro ...

    Indian Academy of Sciences (India)

    Abstract. Powder mixed electro-discharge machining (EDM) is being widely used in modern metal working industry for producing complex cavities in dies and moulds which are otherwise difficult to create by conventional machining route. It has been experimentally demonstrated that the presence of suspended particle in ...

  2. A Nonvolume Preserving Plasticity Theory with Applications to Powder Metallurgy

    Science.gov (United States)

    Cassenti, B. N.

    1983-01-01

    A plasticity theory has been developed to predict the mechanical response of powder metals during hot isostatic pressing. The theory parameters were obtained through an experimental program consisting of hydrostatic pressure tests, uniaxial compression and uniaxial tension tests. A nonlinear finite element code was modified to include the theory and the results of themodified code compared favorably to the results from a verification experiment.

  3. Powder Metallurgy Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The facility is uniquely equipped as the only laboratory within DA to conduct PM processing of refractory metals and alloys as well as the processing of a wide range...

  4. High precision hyperfine measurements in Bismuth challenge bound-state strong-field QED.

    Science.gov (United States)

    Ullmann, Johannes; Andelkovic, Zoran; Brandau, Carsten; Dax, Andreas; Geithner, Wolfgang; Geppert, Christopher; Gorges, Christian; Hammen, Michael; Hannen, Volker; Kaufmann, Simon; König, Kristian; Litvinov, Yuri A; Lochmann, Matthias; Maaß, Bernhard; Meisner, Johann; Murböck, Tobias; Sánchez, Rodolfo; Schmidt, Matthias; Schmidt, Stefan; Steck, Markus; Stöhlker, Thomas; Thompson, Richard C; Trageser, Christian; Vollbrecht, Jonas; Weinheimer, Christian; Nörtershäuser, Wilfried

    2017-05-16

    Electrons bound in highly charged heavy ions such as hydrogen-like bismuth 209 Bi 82+ experience electromagnetic fields that are a million times stronger than in light atoms. Measuring the wavelength of light emitted and absorbed by these ions is therefore a sensitive testing ground for quantum electrodynamical (QED) effects and especially the electron-nucleus interaction under such extreme conditions. However, insufficient knowledge of the nuclear structure has prevented a rigorous test of strong-field QED. Here we present a measurement of the so-called specific difference between the hyperfine splittings in hydrogen-like and lithium-like bismuth 209 Bi 82+,80+ with a precision that is improved by more than an order of magnitude. Even though this quantity is believed to be largely insensitive to nuclear structure and therefore the most decisive test of QED in the strong magnetic field regime, we find a 7-σ discrepancy compared with the theoretical prediction.

  5. Temperature dependence of the hyperfine interaction in the cubic phase of BaHfO3

    International Nuclear Information System (INIS)

    Lopez Garcia, A.R.; de la Presa, P.; Rodriguez, A.M.

    1991-01-01

    The temperature dependence of the hyperfine interaction in the paraelectric phase of BaHfO 3 in the temperature range from liquid-nitrogen temperature to 1350 K has been studied. The experimental results show an Abragam-Pound mechanism for the attenuation of the angular correlation. In this cubic structure the attenuation would be consistent with a relaxation mechanism that involves O-ion hopping between vacant sites in the lattice. Using the point-charge model for the estimation of the electric field gradient produced by an O vacancy in the coordination sphere of the probe ion, the process is characterized by a correlation time τ c =12±1 ps at RT

  6. Hyperfine structure, nuclear spins and magnetic moments of some cesium isotopes

    International Nuclear Information System (INIS)

    Ekstroem, C.; Ingelman, S.; Wannberg, G.

    1977-03-01

    Using an atomic-beam magnetic resonance apparatus connected on-line with the ISOLDE isotope separator, CERN, hyperfine structure measurements have been performed in the 2 Ssub(1/2) electronic ground state of some cesium isotopes. An on-line oven system which efficiently converts a mass separated ion-beam of alkali isotopes to an atomic beam is described in some detail. Experimentally determined nuclear spins of sup(120, 121, 121m, 122, 122m, 123, 124, 126, 128, 130m, 135m)Cs and magnetic moments of sup(122, 123, 124, 126, 128, 130)Cs are reported and discussed in terms of different nuclear models. The experimental data indicate deformed nuclear shapes of the lightest cesium isotopes. (Auth.)

  7. Hyperfine Parameters for Aluminum Hydride: An ab Initio Molecular Orbital Study.

    Science.gov (United States)

    Gee, Myrlene; Wasylishen, Roderick E.

    2001-06-01

    An extensive ab initio molecular orbital study of the (27)Al nuclear spin-rotation and nuclear quadrupolar coupling constants in aluminum hydride, AlH, has been performed. The (27)Al nuclear spin-rotation constant (C( perpendicular)), calculated to be approximately 300 kHz, was neglected in a previous analysis of the hyperfine structure in the microwave spectrum (M. Goto and S. Saito, Astrophys. J. 452, L147-148 (1995)). Unfortunately, the ab initio calculations do not provide a definitive value for the aluminum nuclear quadrupolar coupling constant, but suggest a value of -49+/-4 MHz. It is apparent that the microwave study of AlH should be repeated. Copyright 2001 Academic Press.

  8. Feedback control of the hyperfine ground states of neutral atoms in an optical cavity

    Energy Technology Data Exchange (ETDEWEB)

    Brakhane, Stefan; Alt, Wolfgang; Martinez-Dorantes, Miguel; Kampschulte, Tobias; Reimann, Rene; Meschede, Dieter [Institut fuer Angewandte Physik, Universitaet Bonn, Wegelerstr. 8, 53115 Bonn (Germany); Widera, Artur [Institut fuer Angewandte Physik, Universitaet Bonn, Wegelerstr. 8, 53115 Bonn (Germany); Fachbereich Physik, TU Kaiserslautern, Erwin-Schroedinger-Str., 67663 Kaiserslautern (Germany)

    2011-07-01

    Detection and manipulation of atomic spin states is essential for many experimental realizations of quantum gates. Feedback schemes to stabilize the states and their superpositions can counteract perturbations caused by the environment. In our experiment we deduce the atomic spin state of one or two Caesium atoms by measuring the transmission of a probe laser through a high-finesse cavity. Depending on the number of atoms in the hyperfine state that strongly couples to the cavity, the resonance of the cavity is shifted and the probe laser transmission is decreased. We employ a Bayesian update formalism to obtain time-dependent probabilities for the atomic states of one and two atoms. I present an experimental implementation using a digital signal processor which allows us to determine the atomic spin state in real-time. First experimental results of an extension to a feedback loop for the preparation and stabilization of atomic states are shown.

  9. Nondestructive fluorescence detection of hyperfine states of Rb using an EMCCD camera

    Science.gov (United States)

    Kwon, Minho; Ebert, Matthew; Young, Christopher; Walker, Thad; Saffman, Mark

    2017-04-01

    We demonstrate a method to non-destructively differentiate two hyperfine ground states of trapped neutral 87Rb atoms, with an EMCCD camera. The semi-closed cycling transition limits the number of photons that atoms can scatter before their internal state changes. We utilize circularly polarized probe light and strictly controlled quantization axis to fully close the transition. This enables us to collect sufficient photons for a measurement while preserving the internal state. In our proof of principle experiments up to five trap sites are interrogated in parallel. A few ms of readout time and scalability of the method allow significant speed ups in quantum information experiments with neutral atoms. We also report progress toward Rydberg-mediated gate experiments using ensembles. This work was supported by NSF under award PHY-1521374 and the AFOSR Quantum Memories MURI.

  10. Vibrational branching ratios and hyperfine structure of BH and its suitability for laser cooling

    Directory of Open Access Journals (Sweden)

    Richard eHendricks

    2014-08-01

    Full Text Available The simple structure of the BH molecule makes it an excellent candidate for direct laser cooling. We measure the branching ratios for the decay of the A^{1}Pi (v'=0 state to vibrational levels of the ground state, X^{1}Sigma^{+}, and find that they are exceedingly favourable for laser cooling. We verify that the branching ratio for the spin-forbidden transition to the intermediate a^{3}Pi state is inconsequentially small. We measure the frequency of the lowest rotational transition of the X state, and the hyperfine structure in the relevant levels of both the X and A states, and determine the nuclear electric quadrupole and magnetic dipole coupling constants. Our results show that, with a relatively simple laser cooling scheme, a Zeeman slower and magneto-optical trap can be used to cool, slow and trap BH molecules.

  11. Hyperfine field calculations: search for muon stopping sites in Fe3O4

    International Nuclear Information System (INIS)

    Boekema, C.; Denison, A.B.; Cooke, D.W.; Heffner, R.H.; Hutson, R.L.; Leon, M.; Schillaci, M.E.

    1983-01-01

    Muon Spin Rotation (μSR) results for magnetite (Fe 3 O 4 ) are analyzed and discussed. At room temperature, a μSR signal is observed due to the presence of an internal magnetic field (Bsub(int)) at the muon site. External transverse field measurements show that Bsub(int) is parallel to the magnetic spin direction, the direction in zero applied field. Calculations of the hyperfine field to pinpoint muon stopping sites in magnetite show that the local field contains supertransfer (covalent) and dipolar field contributions. The implanted muons appear to stop at sites structurally similar to those reported for hematite (α-Fe 2 O 3 ), where muon-oxygen bond formation was strongly indicated. (Auth.)

  12. Rotational and hyperfine analysis of the 0, 0 band of the PrO XX system

    Science.gov (United States)

    Dulick, Michael; Field, Robert W.; Beaufils, J. Cl.

    1981-05-01

    The PrO XX 0-0 band is recorded at Doppler-limited resolution by laser excitation spectroscopy with selective fluorescence detection. The rotational and hyperfine structure of this Ω' = 5.5 - Ω″ = 4.5 band is reanalyzed. In addition, fluorescence spectra obtained through excitation of selected rotational lines in the XX 0-0 band and by the 529-nm Ar + laser line have established an energy ordering of four low-lying Ω = 4.5 states and one Ω = 6.5 state as well as ΔG( {1}/{2}) values for the Ω = 6.5 and the two lowest Ω = 4.5 states. Principal constants, in cm -1, are (1σ uncertainties in parentheses, ∗ indicates constant held fixed):

  13. Hyperfine structure of the odd parity level system in the terbium atom

    International Nuclear Information System (INIS)

    Stefanska, D; Furmann, B

    2017-01-01

    Within this work new experimental results concerning the hyperfine structure ( hfs ) in the terbium atom are presented, concerning the odd parity levels system, hitherto only scarcely investigated (apart from the ground term). hfs constants A and B for 113 levels were determined for the first time, and for another 16 levels, which already occurred in our earlier works, supplementary results were obtained; additionally, our earlier results for 93 levels were compiled. The hfs of the odd parity levels was investigated using the method of laser induced fluorescence in a hollow cathode discharge. The hfs of 165 spectral lines, where the levels in question were involved as the upper levels, was recorded. Literature values of hfs constants of the even-parity lower levels (including our own earlier results) greatly facilitated the present data evaluation. (paper)

  14. Hyperfine spectrum measurement of an optically pumped far-infrared laser with a Michelson interferometer

    International Nuclear Information System (INIS)

    Zuo, Z G; Ling, F R; Wang, P; Liu, J S; Yao, J Q; Weng, C X

    2013-01-01

    In this letter, we present a Michelson interferometer for the hyperfine spectrum measurement of an optically pumped far-infrared laser with a highest frequency resolution of 3–5 GHz. CH 3 OH gas with a purity of 99.9%, is pumped by the CO 2 9P36 and 9R10 laser lines to generate terahertz lasers with frequencies of 2.52 and 3.11 THz, respectively. Moreover, except for the center frequency, which is in good agreement with theoretical work, some additional frequencies on both sides of the center frequency are obtained at a frequency interval of 0.15 THz. Meanwhile, the mechanism behind the observed experimental results is also investigated. (letter)

  15. Parametric Powder Diffraction

    Science.gov (United States)

    David, William I. F.; Evans, John S. O.

    The rapidity with which powder diffraction data may be collected, not only at neutron and X-ray synchrotron facilities but also in the laboratory, means that the collection of a single diffraction pattern is now the exception rather than the rule. Many experiments involve the collection of hundreds and perhaps many thousands of datasets where a parameter such as temperature or pressure is varied or where time is the variable and life-cycle, synthesis or decomposition processes are monitored or three-dimensional space is scanned and the three-dimensional internal structure of an object is elucidated. In this paper, the origins of parametric diffraction are discussed and the techniques and challenges of parametric powder diffraction analysis are presented. The first parametric measurements were performed around 50 years ago with the development of a modified Guinier camera but it was the automation afforded by neutron diffraction combined with increases in computer speed and memory that established parametric diffraction on a strong footing initially at the ILL, Grenoble in France. The theoretical parameterisation of quantities such as lattice constants and atomic displacement parameters will be discussed and selected examples of parametric diffraction over the past 20 years will be reviewed that highlight the power of the technique.

  16. Fine and hyperfine collisional excitation of C6H by He

    Science.gov (United States)

    Walker, Kyle M.; Lique, François; Dawes, Richard

    2018-01-01

    Hydrogenated carbon chains have been detected in interstellar and circumstellar media and accurate modelling of their abundances requires collisional excitation rate coefficients with the most abundant species. Among them, the C6H molecule is one of the most abundant towards many lines of sight. Hence, we determined fine and hyperfine-resolved rate coefficients for the excitation of C6H(X2Π) due to collisions with He. We present the first interaction potential energy surface for the C6H-He system, obtained from highly correlated ab initio calculations and characterized by a large anisotropy due to the length of the molecule. We performed dynamical calculations for transitions among the first fine structure levels (up to J = 30.5) of both spin-orbit manifolds of C6H using the close-coupling method, and rate coefficients are determined for temperatures ranging from 5 to 100 K. The largest rate coefficients for even ΔJ transitions conserve parity, while parity-breaking rate coefficients are favoured for odd ΔJ. Spin-orbit changing rate coefficients are several orders of magnitude lower than transitions within a single manifold. State-to-state hyperfine-resolved cross-sections for the first levels (up to J = 13.5) in the Ω = 3/2 spin-orbit manifold are deduced using recoupling techniques. Rate coefficients are obtained and the propensity rule ΔJ = ΔF is seen. These new data will help determine the abundance of C6H in astrophysical environments such as cold dense molecular clouds, star-forming regions and circumstellar envelopes, and will help in the interpretation of the puzzling C6H-/C6H abundance ratios deduced from observations.

  17. Titanium surgical implants processed by powder metallurgy

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, M.V. de [INT-DMCM, Inst. Nacional de Tecnologia, Rio de Janeiro, RJ (Brazil); Pereira, L.C. [Programa de Eng. de Materiais e Metalurgica, UFRJ-COPPE (Brazil); Schwanke, C.M.; Schaeffer, L. [Centro de Tecnologia- LdTM-INT-DMCM, UFRGS, Venezuela, CEP, Rio de Janeiro, RJ (Brazil)

    2001-07-01

    Due to their low density coupled with excellent corrosion resistance and good mechanical properties, titanium and titanium alloys have been widely used for surgical implants. They have also a relatively low young's modulus, allowing a good load transfer to the bone. The elastic modulus difference between metallic implant material and bone is large, which can lead to a fracture of the implant. To solve this problem, many implants for artificial joint and dental applications have been produced by powder metallurgy routes, obtaining a porous material with an even lower young's modulus than that of the bulk titanium. This porous structure allows bone ingrowth, as the osseous tissue invade the holes of the porous material while growing and adheres to it. Besides, near net shape technologies like powder metallurgy and injection molding techniques, can reduce the components high costs due to machining final steps, also providing a fine, uniform grain structure and lack of texture and segregation. This work outlines the characteristics, properties and some of the powder routes for producing titanium surgical implants and implant porous coatings. (orig.)

  18. Sintering of titanium alloy by powder metallurgy

    Energy Technology Data Exchange (ETDEWEB)

    Cosme, C.R.M. [Universidade de Brasilia (UnB), DF (Brazil); Henriques, V.A.R.; Cairo, C.A.A.; Taddei, E.B. [Centro Tecnico Aeroespacial (CTA), Sao Jose dos Campos, SP (Brazil)

    2009-07-01

    Full text: Titanium alloys are suitable for biomaterial applications, considering its biocompatibility and low elastic modulus compared to steel. Bone resorption in this case can be reduced by load sharing between the implant and natural bone.Starting powders were obtained by hydride method, carried out under positive hydrogen pressure at 500 deg C for titanium and 800 deg C for Nb, Zr and Ta powders. After reaching the nominal temperature, the material was held for 3h, with subsequent cooling to room temperature and milling of the friable hydride. Samples were produce by mixing of initial metallic powders followed by and cold isostatic pressing. Subsequent densification by sintering was performed at temperature range between 900 and 1700 deg C. Characterization was carried out with scanning electron microscopy, X-ray diffractometry and microhardness measurements. Microstructural examinations revealed higher amount of &⧣946;-phase for higher sintering temperature and dissolution of Ta and NB particles. In vitro tests revealed low cytotoxicity of sintered samples. (author)

  19. Synthesis and Characterization of Nickel-Alumina Composites from Recycled Nickel Powder

    OpenAIRE

    Karayannis, V. G.; Moutsatsou, A. K.

    2012-01-01

    The recycling of metallic waste to create more valuable materials and their valorization into upgraded metal-based composites constitutes an important field of study. The composite industry nowadays considers environmental improvements as important as other properties of the materials. In the present paper, nickel powder was recycled from ferrous scrap, a low-cost and largely available material, by an effective hydrometallurgical recovery process. Then, this recycled powder was successfully u...

  20. Effect of Powder-Suspended Dielectric on the EDM Characteristics of Inconel 625

    Science.gov (United States)

    Talla, Gangadharudu; Gangopadhyay, S.; Biswas, C. K.

    2016-02-01

    The current work attempts to establish the criteria for powder material selection by investigating the influence of various powder-suspended dielectrics and machining parameters on various EDM characteristics of Inconel 625 (a nickel-based super alloy) which is nowadays regularly used in aerospace, chemical, and marine industries. The powders include aluminum (Al), graphite, and silicon (Si) that have significant variation in their thermo-physical characteristics. Results showed that powder properties like electrical conductivity, thermal conductivity, density, and hardness play a significant role in changing the machining performance and the quality of the machined surface. Among the three powders, highest material removal rate was observed for graphite powder due to its high electrical and thermal conductivities. Best surface finish and least radial overcut (ROC) were attained using Si powder. Maximum microhardness was found for Si due to its low thermal conductivity and high hardness. It is followed by graphite and aluminum powders. Addition of powder to the dielectric has increased the crater diameter due to expansion of plasma channel. Powder-mixed EDM (PMEDM) was also effective in lowering the density of surface cracks with least number of cracks obtained with graphite powder. X-ray diffraction analysis indicated possible formation of metal carbides along with grain growth phenomenon of Inconel 625 after PMEDM.

  1. Considerations on the Construction of a Powder Bed Fusion Platform for Additive Manufacturing

    DEFF Research Database (Denmark)

    Andersen, Sebastian Aagaard; Nielsen, Karl-Emil; Pedersen, David Bue

    2017-01-01

    As the demand for moulds and other tools becomes increasingly specific and complex, an additive manufacturing approach to production is making its way to the industry through laser based consolidation of metal powder particles by a method known as powder bed fusion. This paper concerns a variety...... within such an experimental machine tool, a fully open and customizable rig is constructed. Emphasizing modularity in the rig, allows alternation of lasers, scanner systems, optical elements, powder deposition, layer height, temperature, atmosphere, and powder type. Through a custom-made software...

  2. Nuclear fuel powder transfer device

    International Nuclear Information System (INIS)

    Komono, Akira

    1998-01-01

    A pair of parallel rails are laid between a receiving portion to a molding portion of a nuclear fuel powder transfer device. The rails are disposed to the upper portion of a plurality of parallel support columns at the same height. A powder container is disposed while being tilted in the inside of the vessel main body of a transfer device, and rotational shafts equipped with wheels are secured to right and left external walls. A nuclear powder to be mixed, together with additives, is supplied to the powder container of the transfer device. The transfer device engaged with the rails on the receiving side is transferred toward the molding portion. The wheels are rotated along the rails, and the rotational shafts, the vessel main body and the powder container are rotated. The nuclear powder in the tilted powder container disposed is rotated right and left and up and down by the rotation, and the powder is mixed satisfactory when it reaches the molding portion. (I.N.)

  3. Removing method for powder deposited on nuclear fuel pellet

    International Nuclear Information System (INIS)

    Tajiri, Hiroshi; Yoneda, Kazuhito.

    1996-01-01

    A large number of pellets after completion of a dry-type polishing step are passed, while rolling, on a net plate. The net plate is electroconductive and formed by finely braiding fine metal wires into a lattice. Static electricity (charge) of powders such as a polishing powder deposited on the pellets is discharged on the net plate. The powder from which static electricity is removed are dropped below the net plate by the discharge. In this process, the powders can be dropped from the pellets and the net plate efficiently by vibrating the net plate by an vibration device and the like. A charging electrode is disposed below the net plate, and a dust collecting electrode and a suction blower are disposed therebelow. The powders dropped from the net plate are induced by the suction blower, to which charges are applied by corona discharge at the charging electrode. The charged powders are further induced by the suction blower and collected to the dust collecting device. (I.N.)

  4. Stability of gas atomized reactive powders through multiple step in-situ passivation

    Science.gov (United States)

    Anderson, Iver E.; Steinmetz, Andrew D.; Byrd, David J.

    2017-05-16

    A method for gas atomization of oxygen-reactive reactive metals and alloys wherein the atomized particles are exposed as they solidify and cool in a very short time to multiple gaseous reactive agents for the in-situ formation of a protective reaction film on the atomized particles. The present invention is especially useful for making highly pyrophoric reactive metal or alloy atomized powders, such as atomized magnesium and magnesium alloy powders. The gaseous reactive species (agents) are introduced into the atomization spray chamber at locations downstream of a gas atomizing nozzle as determined by the desired powder or particle temperature for the reactions and the desired thickness of the reaction film.

  5. Considerations on the construction of a Powder Bed Fusion platform for Additive Manufacturing

    Science.gov (United States)

    Andersen, Sebastian Aagaard; Nielsen, Karl-Emil; Pedersen, David Bue; Nielsen, Jakob Skov

    As the demand for moulds and other tools becomes increasingly specific and complex, an additive manufacturing approach to production is making its way to the industry through laser based consolidation of metal powder particles by a method known as powder bed fusion. This paper concerns a variety of design choices facilitating the development of an experimental powder bed fusion machine tool, capable of manufacturing metal parts with strength matching that of conventional manufactured parts and a complexity surpassing that of subtractive processes. To understand the different mechanisms acting within such an experimental machine tool, a fully open and customizable rig is constructed. Emphasizing modularity in the rig, allows alternation of lasers, scanner systems, optical elements, powder deposition, layer height, temperature, atmosphere, and powder type. Through a custom-made software platform, control of the process is achieved, which extends into a graphical user interface, easing adjustment of process parameters and the job file generation.

  6. Nano powders, components and coatings by plasma technique

    Science.gov (United States)

    McKechnie, Timothy N. (Inventor); Antony, Leo V. M. (Inventor); O'Dell, Scott (Inventor); Power, Chris (Inventor); Tabor, Terry (Inventor)

    2009-01-01

    Ultra fine and nanometer powders and a method of producing same are provided, preferably refractory metal and ceramic nanopowders. When certain precursors are injected into the plasma flame in a reactor chamber, the materials are heated, melted and vaporized and the chemical reaction is induced in the vapor phase. The vapor phase is quenched rapidly to solid phase to yield the ultra pure, ultra fine and nano product. With this technique, powders have been made 20 nanometers in size in a system capable of a bulk production rate of more than 10 lbs/hr. The process is particularly applicable to tungsten, molybdenum, rhenium, tungsten carbide, molybdenum carbide and other related materials.

  7. Reduction of UF4 to U metal

    International Nuclear Information System (INIS)

    Suh, I.S.; Kim, J.H.; Min, B.T.; Whang, S.C.; Im, K.S.

    1983-01-01

    The operating conditions for the production of uranium metal by reduction of UFsub(4) with magnesium powder have been thoroughly investigated using the reactor 1 Kg nominal capacity. UFsub(4) powders which were produced from the conversion plant in KAERI are used and MgFsub(2), by-product of the reduction, are used as liner after pulverizing. 95% of average yield of uranium metal are obtained with 6% excess of magnesium powder in size of -πo + 50 mesh and its density is 18.5 g/cc, and furthermore the yield is increased when mafnesium powders are used after washed with trichloro-ethylene and dried. (Author)

  8. Ligand hyperfine structure of Mn2+ in ZnSe as calculated by EHT-SCCC, scattered-wave, and LCAO method

    International Nuclear Information System (INIS)

    Biernacki, S.W.; Hamera, M.; Wartewig, S.

    1977-01-01

    Numerical estimations of the ligand hyperfine structure parameters of ZnSe:Mn 2+ based on three models (Extended Hueckel Theory-Self-Consistent Charge and Configuration, scattered-wave, and LCAO methods) are given

  9. Blackbody radiation shift, multipole polarizabilities, oscillator strengths, lifetimes, hyperfine constants, and excitation energies in Ca+

    International Nuclear Information System (INIS)

    Safronova, M. S.; Safronova, U. I.

    2011-01-01

    A systematic study of Ca + atomic properties is carried out using a high-precision relativistic all-order method where all single, double, and partial triple excitations of the Dirac-Fock wave functions are included to all orders of perturbation theory. Reduced matrix elements, oscillator strengths, transition rates, and lifetimes are determined for the levels up to n=7. Recommended values and estimates of their uncertainties are provided for a large number of electric-dipole transitions. Electric-dipole scalar polarizabilities for the 5s, 6s, 7s, 8s, 4p j , 5p j , 3d j , and 4d j states and tensor polarizabilities for the 4p 3/2 , 5p 3/2 , 3d j , and 4d j states in Ca + are calculated. Methods are developed to accurately treat the contributions from highly excited states, resulting in significant (factor of 3) improvement in the accuracy of the 3d 5/2 static polarizability value, 31.8(3)a 0 3 , in comparison with the previous calculation [Arora et al., Phys. Rev. A 76, 064501 (2007).]. The blackbody radiation shift of the 4s-3d 5/2 clock transition in Ca + is calculated to be 0.381(4) Hz at room temperature, T=300 K. Electric-quadrupole 4s-nd and electric-octupole 4s-nf matrix elements are calculated to obtain the ground-state multipole E2 and E3 static polarizabilities. Excitation energies of the ns, np, nd, nf, and ng states with n≤ 7 in are evaluated and compared with experiment. Recommended values are provided for the 7p 1/2 , 7p 3/2 , 8p 1/2 , and 8p 3/2 removal energies for which experimental measurements are not available. The hyperfine constants A are determined for the low-lying levels up to n=7. The quadratic Stark effect on hyperfine structure levels of 43 Ca + ground state is investigated. These calculations provide recommended values critically evaluated for their accuracy for a number of Ca + atomic properties for use in planning and analysis of various experiments as well as theoretical modeling.

  10. Wavelengths, energy levels and hyperfine structure of Mn II and Sc II.

    Science.gov (United States)

    Nave, Gillian; Pickering, Juliet C.; Townley-Smith, Keeley I. M.; Hala, .

    2015-08-01

    For many decades, the Atomic Spectroscopy Groups at the National Institute of Standards and Technology (NIST) and Imperial College London (ICL) have measured atomic data of astronomical interest. Our spectrometers include Fourier transform (FT) spectrometers at NIST and ICL covering the region 1350 Å to 5.5 μm and a 10.7-m grating spectrometer at NIST covering wavelengths from 300 - 5000 Å. Sources for these spectra include high-current continuous and pulsed hollow cathode (HCL) lamps, Penning discharges, and sliding spark discharges. Recent work has focused on the measurement and analysis of wavelengths, energy levels, and hyperfine structure (HFS) constants for iron-group elements. The analysis of FT spectra of Cr I, Mn I, and Mn II is being led by ICL and is described in a companion poster [1]. Current work being led by NIST includes the analysis of HFS in Mn II, analysis of Mn II in the vacuum ultraviolet, and a comprehensive analysis of Sc II.Comprehensive HFS constants for Mn II are needed for the interpretation of stellar spectra and incorrect abundances may be obtained when HFS is omitted. Holt et al. [2] have measured HFS constants for 59 levels of Mn II using laser spectroscopy. We used FT spectra of Mn/Ni and Mn/Cu HCLs covering wavelength ranges from 1350 Å to 5.4 μm to confirm 26 of the A constants of Holt et al. and obtain values for roughly 40 additional levels. We aim to obtain HFS constants for the majority of lines showing significant HFS that are observed in chemically-peculiar stars.Spectra of Sc HCLs have been recorded from 1800 - 6700 Å using a vacuum ultraviolet FT spectrometer at NIST. Additional measurements to cover wavelengths above 6700 Å and below 1800 Å are in progress. The spectra are being analyzed by NIST and Alighar Muslim University, India in order to derive improved wavelengths, energy levels, and hyperfine structure parameters.This work was partially supported by NASA, the STFC and PPARC (UK), the Royal Society of the UK

  11. Hyperfine-Interaction-Driven Suppression of Quantum Tunneling at Zero Field in a Holmium(III) Single-Ion Magnet.

    Science.gov (United States)

    Chen, Yan-Cong; Liu, Jun-Liang; Wernsdorfer, Wolfgang; Liu, Dan; Chibotaru, Liviu F; Chen, Xiao-Ming; Tong, Ming-Liang

    2017-04-24

    An extremely rare non-Kramers holmium(III) single-ion magnet (SIM) is reported to be stabilized in the pentagonal-bipyramidal geometry by a phosphine oxide with a high energy barrier of 237(4) cm -1 . The suppression of the quantum tunneling of magnetization (QTM) at zero field and the hyperfine structures originating from field-induced QTMs can be observed even from the field-dependent alternating-current magnetic susceptibility in addition to single-crystal hysteresis loops. These dramatic dynamics were attributed to the combination of the favorable crystal-field environment and the hyperfine interactions arising from 165 Ho (I=7/2) with a natural abundance of 100 %. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Searching for an Oscillating Massive Scalar Field as a Dark Matter Candidate Using Atomic Hyperfine Frequency Comparisons.

    Science.gov (United States)

    Hees, A; Guéna, J; Abgrall, M; Bize, S; Wolf, P

    2016-08-05

    We use 6 yrs of accurate hyperfine frequency comparison data of the dual rubidium and caesium cold atom fountain FO2 at LNE-SYRTE to search for a massive scalar dark matter candidate. Such a scalar field can induce harmonic variations of the fine structure constant, of the mass of fermions, and of the quantum chromodynamic mass scale, which will directly impact the rubidium/caesium hyperfine transition frequency ratio. We find no signal consistent with a scalar dark matter candidate but provide improved constraints on the coupling of the putative scalar field to standard matter. Our limits are complementary to previous results that were only sensitive to the fine structure constant and improve them by more than an order of magnitude when only a coupling to electromagnetism is assumed.

  13. Hyperfine-interaction-driven suppression of quantum tunneling at zero field in a holmium(III) single-ion magnet

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yan-Cong; Liu, Jun-Liang; Chen, Xiao-Ming; Tong, Ming-Liang [Key Lab. of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, Sun Yat-Sen Univ., Guangzhou (China); Wernsdorfer, Wolfgang [Institut Neel, CNRS and Universite Joseph Fournier, Grenoble (France); Institute of Nanotechnology, Karlsruhe Institute of Technology (Germany); Physikalisches Institut, Karlsruhe Institute of Technology (Germany); Liu, Dan; Chibotaru, Liviu F. [Theory of Nanomaterials Group and INPAC-Institute of Nanoscale Physics and Chemistry, Katholieke Universiteit Leuven (Belgium)

    2017-04-24

    An extremely rare non-Kramers holmium(III) single-ion magnet (SIM) is reported to be stabilized in the pentagonal-bipyramidal geometry by a phosphine oxide with a high energy barrier of 237(4) cm{sup -1}. The suppression of the quantum tunneling of magnetization (QTM) at zero field and the hyperfine structures originating from field-induced QTMs can be observed even from the field-dependent alternating-current magnetic susceptibility in addition to single-crystal hysteresis loops. These dramatic dynamics were attributed to the combination of the favorable crystal-field environment and the hyperfine interactions arising from {sup 165}Ho (I=7/2) with a natural abundance of 100 %. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. The electronic spectrum of PrO. Energy linkages, rotational analysis, and hyperfine structure for systems XVII and XXI

    Science.gov (United States)

    Dulick, Michael; Field, Robert W.; Beaufils, J. Cl.; Schamps, J.

    1981-05-01

    Doppler-limited laser excitation spectra for four bands of PrO have been recorded: System XvII 0-0, System XXI 0-0 and 0-1, and the 0-0 intercombination between the upper and lower states, respectively, of Systems XVII and XXI. First lines in R and P branches prove that Systems XVII and XXI are, respectively, Ω' = 4.5 - Ω″ = 3.5 and Ω' = Ω″ = 4.5 . Hyperfine components are well resolved for all four excitation bands. Rotational and hyperfine constants are determined by least-squares fits of data from all four bands together. In addition, fluorescence spectra, recorded from various J', v' = 0 levels of the upper states of Systems XVII and XXI, reveal five new low-lying states. Principal constants (in cm -1) for nine Ω-states follow (1σ uncertainty in parentheses):

  15. Magnetism, chemical bonding and hyperfine properties in the nanoscale antiferromagnet [Fe(O Me)2(O2 C C H2 Cl)]10

    International Nuclear Information System (INIS)

    Zeng, Z.; Duan, Y.; Guenzburger, Diana

    1996-09-01

    The electronic and magnetic properties of the nanometer-size antiferromagnet (the ferric wheel molecule) are investigated with the first-principles spin-polarized Discrete Variational Method, in the framework of Density Functional theory. Magnetic moments, densities of the states and charge and spin-density maps are obtained. The Moessbauer hyperfine parameters Isomer shift, Quadrupole Splitting and Hyperfine Field are obtained from the calculations and compared to reported experimental values when available. (author). 33 refs., 8 figs., 4 tabs

  16. (TECTONA GRANDIS LEAF POWDER

    Directory of Open Access Journals (Sweden)

    Yash Mishra

    2015-01-01

    Full Text Available In this study, the adsorption potential of Teak (Tectona grandis leaf powder (TLP toremove Methylene blue (MB and Malachite Green (MG dye molecules from aqueoussolution was investigated. Batch experiments were conducted to evaluate the influenceof operational parameters such as, pH (2−9, adsorbent dosage (1−7 g/L, contact time(15−150 minutes and initial dye concentration (20−120 mg/L at stirring speed of 150rpm for the adsorption of MB and MG on TLP. Maximum removal efficiency of 98.4%and 95.1% was achieved for MB and MG dye, respectively. The experimentalequilibrium data were analysed using Langmuir, Freundlich and Temkin isothermmodels and it was found that, it fitted well to the Freundlich isotherm model. Thesurface structure and morphology of the adsorbent was characterized using scanningelectron microscopy (SEM and the presence of functional groups and its interactionwith the dye molecules were analysed using Fourier transform infrared spectroscopy(FTIR. Based on the investigation, it has been demonstrated that the teak leaf powderhas good potential for effective adsorption of methylene blue and malachite green dye.

  17. ENDOR investigations of the Ce.sup.3+./sup. ions in YAG: Transferred hyperfine interaction with nearest aluminum ions

    Czech Academy of Sciences Publication Activity Database

    Azamat, Dmitry; Badalyan, A. G.; Feng, D.H.; Lančok, Ján; Jastrabík, Lubomír; Dejneka, Alexandr; Baranov, P. G.; Yakovlev, D.R.; Bayer, M.

    2017-01-01

    Roč. 122, č. 24 (2017), s. 1-3, č. článku 243903. ISSN 0021-8979 R&D Projects: GA MŠk LO1409; GA ČR GA16-22092S Institutional support: RVO:68378271 Keywords : laser materials * magnetic resonance imaging * electron nuclear double resonance * hyperfine structure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.068, year: 2016

  18. Fried-Yennie gauge recalculation of the electron line induced radiative-recoil corrections to muonium hyperfine splitting

    International Nuclear Information System (INIS)

    Brook, V.Yu.; Eides, M.I.; Karshenboim, S.G.; Shelyuto, V.A.

    1989-01-01

    A new analytic calculation of radiative-recoil corrections to muonium ground-state hyperfine splitting induced by electron line insertions is performed. The starting point of this calculation is presented by the Fried-Yennie gauge expression for the electron line factor. The final result confirms the one obtained previously from the apparently different expression in the Feynman gauge and removes the slight discrepancy which existed in the literature between the calculations in different gauges. (orig.)

  19. ENDOR investigations of the Ce.sup.3+./sup. ions in YAG: Transferred hyperfine interaction with nearest aluminum ions

    Czech Academy of Sciences Publication Activity Database

    Azamat, Dmitry; Badalyan, A. G.; Feng, D.H.; Lančok, Ján; Jastrabík, Lubomír; Dejneka, Alexandr; Baranov, P. G.; Yakovlev, D.R.; Bayer, M.

    2017-01-01

    Roč. 122, č. 24 (2017), s. 1-3, č. článku 243903. ISSN 0021-8979 R&D Projects: GA MŠk LO1409; GA ČR GA16-22092S Institutional support: RVO:68378271 Keywords : ENDOR * Ce 3+ ions in YAG * transferred hyperfine interactions Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.068, year: 2016

  20. Coherent control of two individual electron spins and influence of hyperfine coupling in a double quantum dot

    International Nuclear Information System (INIS)

    Tarucha, S; Obata, T; Pioro-Ladriere, M; Brunner, R; Shin, Y-S; Kubo, T; Tokura, Y

    2011-01-01

    Electric dipole spin resonance of two individual electrons and the influence of hyperfine coupling on the spin resonance are studied for a double quantum dot equipped with a micro-magnet. The spin resonance occurs by oscillating the electron in each dot at microwave (MW) frequencies in the presence of a micro-magnet induced stray field. The observed continuous wave (CW) and time-resolved spin resonances are consistent with calculations in which the MW induced AC electric field and micro-magnet induced stray field are taken into account. The influence of hyperfine coupling causes an increase and broadening of the respective CW spin resonance peaks through dynamical nuclear polarization when sweeping up the magnetic field. This behaviour appears stronger for the larger of the two spin resonance peaks and in general becomes more pronounced as the MW power increases, both reflecting that the electron-nuclei interaction is more efficient for the stronger spin resonance. In addition the hyperfine coupling effect only becomes pronounced when the MW induced AC magnetic field exceeds the fluctuating nuclear field.

  1. Hyperfine fields in a Ag/Fe magnetic multilayer probed with low energy spin polarized {sup 8}Li

    Energy Technology Data Exchange (ETDEWEB)

    Keeler, T.A. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Salman, Z. [TRIUMF, 4004 Wesbrook Mall, Vancouver, V6T 2A3 (Canada); Chow, K.H. [Department of Physics, University of Alberta, Edmonton, AB, T6G 2J1 (Canada); Heinrich, B. [Department of Physics, Simon Fraser University, Vancouver, BC (Canada); Hossain, M.D. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Kardasz, B. [Department of Physics, Simon Fraser University, Vancouver, BC (Canada); Kiefl, R.F. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada)]. E-mail: kiefl@triumf.ca; Kreitzman, S.R. [TRIUMF, 4004 Wesbrook Mall, Vancouver, V6T 2A3 (Canada); MacFarlane, W.A. [Department of Chemistry, University of British Columbia, Vancouver, V6T 1Z1 (Canada); Mosendz, O. [Department of Physics, Simon Fraser University, Vancouver, BC (Canada); Parolin, T.J. [Department of Chemistry, University of British Columbia, Vancouver, V6T 1Z1 (Canada); Wang, D. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada)

    2006-03-31

    A beam of low energy Li8 has been used to probe the hyperfine field distribution in a magnetic multilayer composed of Au(4nm)/Ag(80nm)/Fe(2nm) grown on a GaAs substrate. The {beta}-NMR frequency spectrum is shown to be a strong function of the implantation energy reflecting the depth dependence of the local hyperfine fields. Correlating the spectra with TRIM.SP implantation profiles allows us to identify signals from the GaAs, Ag and Au layers. The frequency spectrum in Ag is a strong function of energy. A very narrow line, and corresponding distribution of hyperfine fields, is observed when the beam in centered well away from the Fe whereas a much broader distribution is observed when the Li stops close to the Fe. These results demonstrate that low energy {beta}-NMR can act as a sensitive probe of the induced magnetism in the otherwise non-magnetic Ag spacer layers.

  2. Theoretical Study of the Feasibility of Laser Cooling the24Mg35Cl Molecule Including Hyperfine Structure and Branching Ratios.

    Science.gov (United States)

    Yang, Quan-Shun; Li, Shi-Chang; Yu, You; Gao, Tao

    2018-03-13

    The possibility of laser cooling the 24 Mg 35 Cl molecule is investigated using the electronic, rovibrational, and hyperfine structure. Twelve low-lying Λ-S electronic states of the 24 Mg 35 Cl molecule have been calculated at the multireference configuration interaction level of theory. The spin-orbit coupling effects are taken into account in the electronic structure calculations. Spectroscopic constants agree well with previously obtained theoretical and experimental values. On the basis of the potential energy curves and transition dipole moments, the highly diagonally distributed Franck-Condon factors for the A 2 Π → X 2 Σ + transition and short radiative lifetime of the A 2 Π state are determined. Then, employing a quantum effective Hamiltonian approach, we investigate the hyperfine manifolds of the X 2 Σ + state and obtain the zero-field hyperfine spectrum with the errors relative to the experimental data not exceeding 8-20 kHz. Finally, we design a laser cooling scheme with one cooling main laser beam and two repumping laser beams with modulated sidebands, which is sufficient for the implementation of efficient laser slowing and cooling of the 24 Mg 35 Cl molecule. Moreover, it is important to note that the dissociation energy (2.2593 eV) of the B 2 Σ + state is obtained for the first time at the multireference configuration interaction level. We hope that this can provide a helpful reference for experimental observation.

  3. Consolidation of powders of the superconductor YBa/sub 2/Cu/sub 3/O/sub 7-. delta. / by high energy-high rate processing

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J.Y.; Persad, C.; Swinnea, J.S.; Marcus, H.L.; Steinfink, H. (Texas Univ., Austin, TX (USA). Center for Materials Science and Engineering)

    1988-01-01

    The consolidation response of powders of the superconducting compound YBa/sub 2/Cu/sub 3/O/sub 7-{delta}/ by itself and admixed with metal powders is reported. The processing approach relies on short duration (powders under applied pressures of 200 MPa to 400 MPa. Powders and fabricated disk concepts were characterized by X-ray diffraction, optical and scanning electron microscopy.

  4. Improving Powder Injection Molding: an Opportunity for the Aerospace Industry

    Directory of Open Access Journals (Sweden)

    I. Emri

    2014-01-01

    Full Text Available This work deals with powder injection molding (PIM technology of metal and ceramis powders using polyoximethylene (POM binder. In this study, two ways to decrease the viscosity of PIM feedstock materials with polyoxymethylene were investigated. The first way was to reduce the average molecular weight (AMV of the binder and the second one to select a polydisperse particle size distribution with high maximum packing fraction. It was shown that binder with AMW equal to 24410 g/mol gives required level of viscosity around 10 Pa/s. It was shown that using the low disperse powder with wide size distribution can lead to volumetric loading of approximately 83 %. Moreover, using such a feedstock has viscosity lower than required by PIM technology 1000 Pa/s.

  5. Glycine-nitrate combustion synthesis of oxide ceramic powders

    Energy Technology Data Exchange (ETDEWEB)

    Chick, L.A.; Pederson, L.R.; Maupin, G.D.; Bates, J.L.; Thomas, L.E.; Exarhos, G.J. (Pacific Northwest Lab., Richland, WA (United States))

    1990-09-01

    A new combustion synthesis method, the glycine-nitrate process, has been used to prepare oxide ceramic powders, including substituted chromite and manganite powders of high quality. A precursor was prepared by combining glycine with metal nitrates in their appropriate stoichiometric ratios in an aqueous solution. The precursor was heated to evaporate excess water, yielding a viscous liquid. Further heating to about 180[degrees]C caused the precursor liquid to autoignite. Combustion was rapid and self-sustaining, with flame temperatures ranging from 1100 to 1450[degrees]C. The chromite product was compositionally homogeneous with a specific surface area of 32 m[sup 2]/g, while the manganite product was composed of two distinct phases with a 23 m[sup 2]/g surface area after calcination. When compared to similar compositions made using the amorphous citrate process, glycine-nitrate-produced powders had greater compositional uniformity, lower residual carbon levels and smaller particle sizes.

  6. Experiment for the first direct measurement of the hyperfine splitting of positronium

    Energy Technology Data Exchange (ETDEWEB)

    Miyazaki, A; Ishida, A; Asai, S [Department of Physics, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 133-0033 (Japan); Suehara, T; Namba, T; Kobayashi, T [International Center for Elementary Particle Physics (ICEPP), The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 (Japan); Saito, H [Department of General Systems Studies, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902 (Japan); Yoshida, M [Accelerator Laboratory, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki, 305-0801 (Japan); Idehara, T; Ogawa, I; Urushizaki, Y [Research Center for Development of Far-Infrared Region, University of Fukui (FIR-FU), 3-9-1 Bunkyo, Fukui, Fukui, 910-8507 (Japan); Sabchevski, S, E-mail: miyazaki@icepp.s.u-tokyo.ac.j [Bulgarian Academy of Science, 1, 15 Noemvri Str., 1040 Sofia (Bulgaria)

    2010-04-01

    Positronium is an ideal system for the research of the bound state QED. The hyperfine splitting of positronium (Ps-HFS: about 203 GHz) is a good tool to test QED and also sensitive to new physics beyond the Standard Model via a quantum oscillation between an ortho-Ps and a virtual photon. Previous experimental results show 3.9 {sigma} (15 ppm) discrepancy from the QED calculation. All previous experiments used an indirect method with static magnetic field to cause Zeeman splitting (a few GHz) between triplet states of ortho-Ps, from which the HFS value was derived. One possible systematic error source of the indirect method is non-uniformity of the static magnetic field. We are developing a new direct Ps-HFS measurement system without static magnetic field. In this measurement we use a gyrotron, a novel sub-THz light source, with a high-finesse Fabry-Perot cavity to obtain enough radiation power at 203 GHz. The present status of the optimization studies and current design of the experiment are described.

  7. Velocity dependence of transient hyperfine field at Pt ions rapidly recoiling through magnetized Fe

    International Nuclear Information System (INIS)

    Stuchbery, A.E.; Ryan, C.G.; Bolotin, H.H.

    1981-01-01

    The velocity-dependence of the transient hyperfine magnetic field acting at nuclei of 196 Pt ions rapidly recoiling through thin magnetized Fe was investigated at a number of recoil velocities. The state of interest (2 1 + ) was populated by Coulomb excitation using beams of 80- and 120-MeV 32 S and 150- and 220-MeV 58 Ni ions. The 2 1 + →0 1 + γ-ray angular distribution precession measurements were carried out in coincidence with backscattered projectiles. From these results, the strength of the transient field acting on Pt ions recoiling through magnetized Fe with average velocities in the extended range 2.14<=v/vsub(o)<=4.82 (vsub(o) = c/137) was found to be consistent with a linear velocity dependence and to be incompatible with the specific vsup(0.45+-0.18) dependence which has been previously reported to account well for all ions in the mass range from oxygen through samarium. This seemingly singular behaviour for Pt and other ions in the Pt mass vicinity is discussed

  8. Effect of Charge Localization on the Effective Hyperfine Interaction in Organic Semiconducting Polymers

    Science.gov (United States)

    Geng, Rugang; Subedi, Ram C.; Luong, Hoang M.; Pham, Minh T.; Huang, Weichuan; Li, Xiaoguang; Hong, Kunlun; Shao, Ming; Xiao, Kai; Hornak, Lawrence A.; Nguyen, Tho D.

    2018-02-01

    Hyperfine interaction (HFI), originating from the coupling between spins of charge carriers and nuclei, has been demonstrated to strongly influence the spin dynamics of localized charges in organic semiconductors. Nevertheless, the role of charge localization on the HFI strength in organic thin films has not yet been experimentally investigated. In this study, the statistical relation hypothesis that the effective HFI of holes in regioregular poly(3-hexylthiophene) (P3HT) is proportional to 1 /N0.5 has been examined, where N is the number of the random nuclear spins within the envelope of the hole wave function. First, by studying magnetoconductance in hole-only devices made by isotope-labeled P3HT we verify that HFI is indeed the dominant spin interaction in P3HT. Second, assuming that holes delocalize fully over the P3HT polycrystalline domain, the strength of HFI is experimentally demonstrated to be proportional to 1 /N0.52 in excellent agreement with the statistical relation. Third, the HFI of electrons in P3HT is about 3 times stronger than that of holes due to the stronger localization of the electrons. Finally, the effective HFI in organic light emitting diodes is found to be a superposition of effective electron and hole HFI. Such a statistical relation may be generally applied to other semiconducting polymers. This Letter may provide great benefits for organic optoelectronics, chemical reaction kinetics, and magnetoreception in biology.

  9. Maraging-350 steel: Following the aging through diffractometric, magnetic and hyperfine analysis

    Energy Technology Data Exchange (ETDEWEB)

    Nunes, G.C.S. [Universidade Estadual de Maringá, Departamento de Física, Av. Colombo, 5790, PR, 87.020-900 Brazil (Brazil); Sarvezuk, P.W.C. [Universidade Tecnológica Federal do Paraná, Campo Mourão, PR (Brazil); Alves, T.J.B.; Biondo, V.; Ivashita, F.F. [Universidade Estadual de Maringá, Departamento de Física, Av. Colombo, 5790, PR, 87.020-900 Brazil (Brazil); Paesano, A., E-mail: paesano@wnet.com.br [Universidade Estadual de Maringá, Departamento de Física, Av. Colombo, 5790, PR, 87.020-900 Brazil (Brazil)

    2017-01-01

    Plates of solution annealed Maraging-350 steel were submitted to aging under an inert atmosphere, varying the time and temperature. The aged samples were characterized by X-ray diffraction and Mössbauer spectroscopy. The results revealed that the aging treatments induced the reversion of austenite, in amounts that vary with the time and the temperature of the heat treatment. The lattice parameters of the martensite and austenite phases, as well as their hyperfine parameters, were obtained at all aging conditions. No intermetallic compounds were identified in any of the aged samples, but a poorly crystallized phase fraction, the consequence of an incomplete martensite ⇒ austenite reversion transformation, was observed for some samples. The tetragonal distortion from cubic symmetry presented by the martensite in the solution annealed steel was not eliminated after aging. - Highlights: • We report a fine characterization of aged Maraging-350 steel. • Martensite shows a crystallographic distortion from the cubic symmetry. • Reverted austenite is present in amounts that depend on the aging conditions. • Properties measured are key information for a proper control of the steel aging.

  10. Singlet-to-triplet interconversion using hyperfine as well as ferromagnetic fringe fields.

    Science.gov (United States)

    Wohlgenannt, M; Flatté, M E; Harmon, N J; Wang, F; Kent, A D; Macià, F

    2015-06-28

    Until recently the important role that spin-physics ('spintronics') plays in organic light-emitting devices and photovoltaic cells was not sufficiently recognized. This attitude has begun to change. We review our recent work that shows that spatially rapidly varying local magnetic fields that may be present in the organic layer dramatically affect electronic transport properties and electroluminescence efficiency. Competition between spin-dynamics due to these spatially varying fields and an applied, spatially homogeneous magnetic field leads to large magnetoresistance, even at room temperature where the thermodynamic influences of the resulting nuclear and electronic Zeeman splittings are negligible. Spatially rapidly varying local magnetic fields are naturally present in many organic materials in the form of nuclear hyperfine fields, but we will also review a second method of controlling the electrical conductivity/electroluminescence, using the spatially varying magnetic fringe fields of a magnetically unsaturated ferromagnet. Fringe-field magnetoresistance has a magnitude of several per cent and is hysteretic and anisotropic. This new method of control is sensitive to even remanent magnetic states, leading to different conductivity/electroluminescence values in the absence of an applied field. We briefly review a model based on fringe-field-induced polaron-pair spin-dynamics that successfully describes several key features of the experimental fringe-field magnetoresistance and magnetoelectroluminescence. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  11. Hyperfine structure measurements of neutral iodine atom (127I) using Fourier Transform Spectrometry

    Science.gov (United States)

    Ashok, Chilukoti; Vishwakarma, S. R.; Bhatt, Himal; Ankush, B. K.; Deo, M. N.

    2018-01-01

    We report the hyperfine Structure (hfs) splitting observations of neutral iodine atom (II) in the 6000 - 10,000 cm-1 near infrared spectral region. The measurements were carried out using a high-resolution Fourier Transform Spectrometer (FTS), where an electrodeless discharge lamp (EDL), excited using microwaves, was employed as the light source and InGaAs as the light detector. A specially designed setup was used to lower the plasma temperature of the medium so as to reduce the Doppler width and consequently to increase the spectral resolution of hfs components. A total of 183 lines with hfs splitting have been observed, out of which hfs in 53 spectral lines are reported for the first time. On the basis of hfs analysis, we derived the magnetic dipole and electric quadrupole coupling constants, A and B respectively for 30 even and 30 odd energy levels and are compared with the values available in the literature. New hfs values for 5 even and 4 odd levels are also reported here for the first time.

  12. In-beam measurement of the hydrogen hyperfine splitting and prospects for antihydrogen spectroscopy

    Science.gov (United States)

    Diermaier, M.; Jepsen, C. B.; Kolbinger, B.; Malbrunot, C.; Massiczek, O.; Sauerzopf, C.; Simon, M. C.; Zmeskal, J.; Widmann, E.

    2017-06-01

    Antihydrogen, the lightest atom consisting purely of antimatter, is an ideal laboratory to study the CPT symmetry by comparison with hydrogen. With respect to absolute precision, transitions within the ground-state hyperfine structure (GS-HFS) are most appealing by virtue of their small energy separation. ASACUSA proposed employing a beam of cold antihydrogen atoms in a Rabi-type experiment, to determine the GS-HFS in a field-free region. Here we present a measurement of the zero-field hydrogen GS-HFS using the spectroscopy apparatus of ASACUSA's antihydrogen experiment. The measured value of νHF=1,420,405,748.4(3.4) (1.6) Hz with a relative precision of 2.7 × 10-9 constitutes the most precise determination of this quantity in a beam and verifies the developed spectroscopy methods for the antihydrogen HFS experiment to the p.p.b. level. Together with the recently presented observation of antihydrogen atoms 2.7 m downstream of the production region, the prerequisites for a measurement with antihydrogen are now available within the ASACUSA collaboration.

  13. In-beam measurement of the hydrogen hyperfine splitting and prospects for antihydrogen spectroscopy.

    Science.gov (United States)

    Diermaier, M; Jepsen, C B; Kolbinger, B; Malbrunot, C; Massiczek, O; Sauerzopf, C; Simon, M C; Zmeskal, J; Widmann, E

    2017-06-12

    Antihydrogen, the lightest atom consisting purely of antimatter, is an ideal laboratory to study the CPT symmetry by comparison with hydrogen. With respect to absolute precision, transitions within the ground-state hyperfine structure (GS-HFS) are most appealing by virtue of their small energy separation. ASACUSA proposed employing a beam of cold antihydrogen atoms in a Rabi-type experiment, to determine the GS-HFS in a field-free region. Here we present a measurement of the zero-field hydrogen GS-HFS using the spectroscopy apparatus of ASACUSA's antihydrogen experiment. The measured value of ν HF =1,420,405,748.4(3.4) (1.6) Hz with a relative precision of 2.7 × 10 -9 constitutes the most precise determination of this quantity in a beam and verifies the developed spectroscopy methods for the antihydrogen HFS experiment to the p.p.b. level. Together with the recently presented observation of antihydrogen atoms 2.7 m downstream of the production region, the prerequisites for a measurement with antihydrogen are now available within the ASACUSA collaboration.

  14. Helium Pressure Shift of the Hyperfine Clock Transition in Hg-201(+)

    Science.gov (United States)

    Larigani, S. Taghavi; Burt, E. A.; Tjoelker, R. L.

    2010-01-01

    There are two stable odd isotopes of mercury with singly ionized hyperfine structure suitable for a microwave atomic clock: Hg-199(+) and Hg-201(+). We are investigating the viability of a trapped ion clock based on Hg-201(+) in a configuration that uses a buffer gas to increase ion loading efficiency and counter ion heating from rf trapping fields. Traditionally, either helium or neon is used as the buffer gas at approx. 10(exp -5) torr to confine mercury ions near room temperature. In addition to the buffer gas, other residual background gasses such as H2O, N2, O2, CO, CO2, and CH2 may be present in trace quantities. Collisions between trapped ions and buffer gas or background gas atoms/molecules produce a momentary shift of the ion clock transition frequency and constitute one of the largest systematic effects in this type of clock. Here we report an initial measurement of the He pressure shift in Hg-201(+) and compare this to Hg-199(+).

  15. Experimental and theoretical study of the hyperfine structure in the lower configurations in 45Sc II

    International Nuclear Information System (INIS)

    Villemoes, P.; van Leeuwen, R.; Arnesen, A.; Heijkenskjoeld, F.; Kastberg, A.; Larsson, M.O.; Kotochigova, S.A.

    1992-01-01

    We have measured the hyperfine structure (hfs) of 12 levels in the configurations 3d4s, 3d 2 , and 3d4p in singly ionized scandium by collinear fast-ion-beam--laser spectroscopy. The hfs of the four levels in the configuration 3d4s has to our knowledge not been measured before. From these levels the ions were excited to levels in the 3d4p configuration by the frequency-doubled output of a ring dye laser with an intracavity mounted LiIO 3 crystal. Levels in the 3d 2 configuration were excited to levels in the 3d4p configuration with visible laser light. The resulting magnetic dipole (A) and electric quadrupole (B) hfs constants are analyzed in Sandars-Beck effective-operator formalism. The multiconfiguration Dirac-Fock method has been used to calculate the hfs constants for levels in the configurations 3d4s, 3d5s, 3d6s, 3d 2 , and 3d4p. Within the framework of the configuration-interaction method, an approach is presented for the calculation of the core polarization, which uses a virtual basis set localized inside the core. For all levels, this approach gives better results compared to previously published calculations

  16. Neutron Powder Diffraction in Sweden

    International Nuclear Information System (INIS)

    Tellgren, R.

    1986-01-01

    Neutron powder diffraction in Sweden has developed around the research reactor R2 in Studsvik. The article describes this facility and presents a historical review of research results obtained. It also gives some ideas of plans for future development

  17. Rotary powder feed through apparatus

    Science.gov (United States)

    Lewis, Gary K.; Less, Richard M.

    2001-01-01

    A device for increasing the uniformity of solids within a solids fabrication system, such as a direct light fabrication (DLF) system in which gas entrained powders are passed through the focal point of a moving high-power light which fuses the particles in the powder to a surface being built up in layers. The invention provides a feed through interface wherein gas entrained powders input from stationary input lines are coupled to a rotating head of the fabrication system. The invention eliminates the need to provide additional slack in the feed lines to accommodate head rotation, and therefore reduces feed line bending movements which induce non-uniform feeding of gas entrained powder to a rotating head.

  18. Silica coated magnetite nanoparticles for removal of heavy metal ions from polluted waters

    CERN Document Server

    Dash, Monika

    2013-01-01

    Magnetic removal of Hg2+ and other heavy metal ions like Cd2+, Pb2+ etc. using silica coated magnetite particles from polluted waters is a current topic of active research to provide efficient water recycling and long term high quality water. The technique used to study the bonding characteristics of such kind of nanoparticles with the heavy metal ions is a very sensitive hyperfine specroscopy technique called the perturbed angular correlation technique (PAC).

  19. Dry and coating of powders

    International Nuclear Information System (INIS)

    Alonso, M.; Alguacil, F. J.

    1999-01-01

    This paper presents a review on the mixing and coating of powders by dry processes. The reviews surveys fundamental works on mixture characterization (mixing index definitions and sampling techniques), mixing mechanisms and models, segregation with especial emphasis on free-surface segregation, mixing of cohesive powders and interparticle forces, ordered mixing (dry coating) including mechanism, model and applications and mixing equipment selection. (Author) 180 refs

  20. Decomposition of metal nitrate solutions

    International Nuclear Information System (INIS)

    Haas, P.A.; Stines, W.B.

    1982-01-01

    Oxides in powder form are obtained from aqueous solutions of one or more heavy metal nitrates (e.g. U, Pu, Th, Ce) by thermal decomposition at 300 to 800 deg C in the presence of about 50 to 500% molar concentration of ammonium nitrate to total metal. (author)