Sample records for complex intermetallic compounds

  1. Surfaces of complex intermetallic compounds: insights from density functional calculations.

    PubMed

    Hafner, Jürgen; Kraj?í, Marian

    2014-11-18

    CONSPECTUS: Complex intermetallic compounds are a class of ordered alloys consisting of quasicrystals and other ordered compounds with large unit cells; many of them are approximant phases to quasicrystals. Quasicrystals are the limiting case where the unit cell becomes infinitely large; approximants are series of periodic structures converging to the quasicrystal. While the unique properties of quasicrystals have inspired many investigations of their surfaces, relatively little attention has been devoted to the surface properties of the approximants. In general, complex intermetallic compounds display rather irregular, often strongly corrugated surfaces, making the determination of their atomic structure a very complex and challenging task. During recent years, scanning tunneling microscopy (STM) has been used to study the surfaces of several complex intermetallic compounds. If atomic resolution can be achieved, STM permits visualization of the local atomistic surface structure. However, the interpretation of the STM images is often ambiguous and sometimes even impossible without a realistic model of the structure of the surface and the distribution of the electronic density above the surface. Here we demonstrate that ab initio density functional theory (DFT) can be used to determine the energetics and the geometric and electronic structures of the stable surfaces of complex intermetallic compounds. Calculations for surfaces with different chemical compositions can be performed in the grand canonical ensemble. Simulated cleavage experiments permit us to determine the formation of the cleavage planes requiring the lowest energy. The investigation of the adsorption of molecular species permits a comparison with temperature-programmed thermal desorption experiments. Calculated surface electronic densities of state can be compared with the results of photoelectron spectroscopy. Simulations of detailed STM images can be directly confronted with the experimental results. Detailed results are presented for two intermetallic compounds that have recently attracted much attention as active and highly selective catalysts for the semihydrogenation of alkynes to alkenes, but the identification of the catalytically active surfaces was found to be very difficult. The crystal structure of B20-type GaPd can be interpreted as the lowest order approximant of icosahedral Al-Pd-Mn quasicrystals. Among the low-index surfaces, the {100} surface shows 2-fold symmetry and the {210} surface pseudo-5-fold symmetry; for both the surface stoichiometry is identical to that of the bulk. Because the structure lacks inversion symmetry, the {111} surfaces have polar character and permit terminations of widely different chemical composition. Results for all three surfaces are presented and compared with the available experiments. The crystal structure of orthorhombic Al13Co4 is built by pentagonal clusters similar to those found in decagonal Al-Co and Al-Ni-Co quasicrystals. A simulated cleavage experiment shows that the constituent clusters remain intact upon cleavage, resulting in the formation of a highly corrugated (100) surface. The calculated STM images are found to be in very good agreement with experiment and permit in addition identification of possible surface modifications by the desorption of individual atoms. Pentagonal motifs on the {210} surface of GaPd and on the (100) surface of Al13Co4 consisting of simple- and transition-metal atoms have been identified as the catalytically active centers for the semihydrogenation of acetylene to ethylene. PMID:24741993

  2. Structural and Electronic Investigations of Complex Intermetallic Compounds

    SciTech Connect

    Hyunjin Ko

    2008-08-18

    In solid state chemistry, numerous investigations have been attempted to address the relationships between chemical structure and physical properties. Such questions include: (1) How can we understand the driving forces of the atomic arrangements in complex solids that exhibit interesting chemical and physical properties? (2) How do different elements distribute themselves in a solid-state structure? (3) Can we develop a chemical understanding to predict the effects of valence electron concentration on the structures and magnetic ordering of systems by both experimental and theoretical means? Although these issues are relevant to various compound classes, intermetallic compounds are especially interesting and well suited for a joint experimental and theoretical effort. For intermetallic compounds, the questions listed above are difficult to answer since many of the constituent atoms simply do not crystallize in the same manner as in their separate, elemental structures. Also, theoretical studies suggest that the energy differences between various structural alternatives are small. For example, Al and Ga both belong in the same group on the Periodic Table of Elements and share many similar chemical properties. Al crystallizes in the fcc lattice with 4 atoms per unit cell and Ga crystallizes in an orthorhombic unit cell lattice with 8 atoms per unit cell, which are both fairly simple structures (Figure 1). However, when combined with Mn, which itself has a very complex cubic crystal structure with 58 atoms per unit cell, the resulting intermetallic compounds crystallize in a completely different fashion. At the 1:1 stoichiometry, MnAl forms a very simple tetragonal lattice with two atoms per primitive unit cell, while MnGa crystallizes in a complicated rhombohedral unit cell with 26 atoms within the primitive unit cell. The mechanisms influencing the arrangements of atoms in numerous crystal structures have been studied theoretically by calculating electronic structures of these and related materials. Such calculations allow us to examine various interactions at the atomic scale, interactions which include orbital overlap, two-electron interactions, and Madelung terms. Moreover, these electronic studies also provide links between the angstrom-scale atomic interactions and the macro-scale physical properties, such as magnetism. Over the past few decades, there have been many significant developments toward understanding structure-bonding-property relationships in extended solids in terms of variables including atomic size, valence electron concentration, and electronegativity. However, many simple approaches based on electron counting, e.g., the octet rule, the 18-electron rule, or Wade's rules for boranes, cannot be applied adequately or universally to many of the more complex intermetallic compounds. For intermetallic phases that include late transition metals and post transition main group elements as their constituents, one classification scheme has been developed and effectively applied by using their valence electron count per atom (vec). These compounds are known as Hume-Rothery electron phases, and they have a variety of structure types with vec < 2.0 as shown in Table 1.

  3. New method for computer analysis of complex intermetallic compounds and nanocluster model of the samson phase Cd3Cu4

    NASA Astrophysics Data System (ADS)

    Blatov, V. A.; Ilyushin, G. D.

    2010-12-01

    A new method is proposed for the computer analysis of crystal structures of complex intermetallic compounds (with more than 1000 atoms per unit cell) using a developed algorithm of the complete decomposition of the 3D graph of the structure into nanocluster substructures. This method has been implemented in the TOPOS software package and approved successfully in an analysis of the complex Cu3Cd4 structure (Samson phase). Cu3Cd4 structure models were used to establish a structural relationship between nanoclusters in this intermetallic compound and nanoclusters in other complex crystal structures: ZrZn22, Ru7Mg44, NaCd2, and Mg2Al3.

  4. Growth of New Intermetallic Compounds from Aluminum Flux

    E-print Network

    Kanatzidis, Mercouri G

    delocalized; larger phase width Intermetallics PtAl2, TiAl3 Complex structures, metallic conductivityAl4: very common structure for binary and ternary intermetallics Tetragonal I4/mmm All the quaternaryGrowth of New Intermetallic Compounds from Aluminum Flux Susan E. Latturner Department of Chemistry

  5. NUCLEAR ORIENTATION EXPERIMENTS ON CERIUM INTERMETALLIC COMPOUNDS

    E-print Network

    Paris-Sud XI, Université de

    L-63 NUCLEAR ORIENTATION EXPERIMENTS ON CERIUM INTERMETALLIC COMPOUNDS A. BENOIT, J. FLOUQUET, M magnetic measurements, this last conclusion is dubious as the crystalline anisotropy of theI + 3/2 ~ cerium

  6. Crystal structure analysis of intermetallic compounds

    NASA Technical Reports Server (NTRS)

    Conner, R. A., Jr.; Downey, J. W.; Dwight, A. E.

    1968-01-01

    Study concerns crystal structures and lattice parameters for a number of new intermetallic compounds. Crystal structure data have been collected on equiatomic compounds, formed between an element of the Sc, Ti, V, or Cr group and an element of the Co or Ni group. The data, obtained by conventional methods, are presented in an easily usable tabular form.

  7. The atomic structure of two intermetallic compounds

    Microsoft Academic Search

    E A Owen; G D Preston

    1923-01-01

    The two intermetallic compounds Mg2Si and AlSb have been examined by the X-ray spectrometer with the following results: - Mg2Si. - A face centred cubic lattice of silicon atoms of side 6.391Å symmetrically intermeshed with a simple cubic lattice of magnesium atoms of side 3.19Å. There are eight magnesium atoms situated within each face centred cube of silicon atoms, dividing

  8. SYNTHESIS AND CHARACTERIZATION OF NEW INTERMETALLIC COMPOUNDS

    SciTech Connect

    Professor Monica Sorescu

    2003-05-07

    This six-month work is focused mainly on the properties of novel magnetic intermetallics. In the first project, we synthesized several 2:17 intermetallic compounds, namely Nd{sub 2}Fe{sub 15}Si{sub 2}, Nd{sub 2}Fe{sub 15}Al{sub 2}2, Nd{sub 2}Fe{sub 15}SiAl and Nd{sub 2}Fe{sub 15}SiMn, as well as several 1:12 intermetallic compounds, such as NdFe{sub 10}Si{sub 2}, NdFe{sub 10}Al{sub 2}, NdFe{sub 10}SiAl and NdFe{sub 10}MnAl. In the second project, seven compositions of Nd{sub x}Fe{sub 100-x-y}B{sub y} ribbons were prepared by a melt spinning method with Nd and B content increasing from 7.3 and 3.6 to 11 and 6, respectively. The alloys were annealed under optimized conditions to obtain a composite material consisting of the hard magnetic Nd{sub 2}Fe{sub 14}B and soft magnetic {alpha}-Fe phases, typical of a spring magnet structure. In the third project, intermetallic compounds of the type Zr{sub 1}Cr{sub 1}Fe{sub 1}T{sub 0.8} with T=Al, Co and Fe were subjected to hydrogenation. In the fourth project, we performed three crucial experiments. In the first experiment, we subjected a mixture of Fe{sub 3}O{sub 4} and Fe(80-20 wt%) to mechanochemical activation by high-energy ball milling, for time periods ranging from 0.5 to 14 hours. In the second experiment, we ball-milled Fe{sub 3}O{sub 4}:Co{sup 2+} (x=0.1) for time intervals between 2.5 and 17.5 hours. Finally, we exposed a mixture of Fe{sub 3}O{sub 4} and Co(80-20 wt%) to mechanochemical activation for time periods ranging from 0.5 to 10 hours. In all cases, the structural and magnetic properties of the systems involved were elucidated by X-ray diffraction (XRD), Moessbauer spectroscopy and hysteresis loop measurements. The four projects resulted in four papers, which are currently being considered for publication in Intermetallics, IEEE Transactions on Magnetics, Journal of Materials Science Letters and Journal of Materials Science. The contributions reveal for the first time in literature the effect of substitutions on the hyperfine magnetic field of neodymium-based intermetallics, the correlation between structure and magnetic properties in spring magnets, the unique effects induced by hydrogenation on the hyperfine parameters of iron-rich intermetallics and the characteristics of the ball milling process in systems containing magnetite.

  9. Structure determination of intermetallic compounds using electron crystallography methods

    E-print Network

    Vardi, Amichay

    Structure determination of intermetallic compounds using electron crystallography methods Louisa and minerals were solved using PED technique. Until today structure of intermetallic compounds was never solved Structure and properties of materials are intimately linked, thus study of crystal structure of novel

  10. Driving magnetostructural transitions in layered intermetallic compounds.

    PubMed

    Wang, J L; Caron, L; Campbell, S J; Kennedy, S J; Hofmann, M; Cheng, Z X; Din, M F Md; Studer, A J; Brück, E; Dou, S X

    2013-05-24

    We report the dramatic effect of applied pressure and magnetic field on the layered intermetallic compound Pr(0.5)Y(0.5)Mn(2)Ge(2). In the absence of pressure or magnetic field this compound displays interplanar ferromagnetism at room temperature and undergoes an isostructural first order magnetic transition (FOMT) to an antiferromagnetic state below 158 K, followed by another FOMT at 50 K due to the reemergence of ferromagnetism as praseodymium orders (T(C)(Pr)). The application of a magnetic field drives these two transitions towards each other, whereas the application of pressure drives them apart. Pressure also produces a giant magnetocaloric effect such that a threefold increase of the entropy change associated with the lower FOMT (at T(C)(Pr)) is seen under a pressure of 7.5 kbar. First principles calculations, using density functional theory, show that this remarkable magnetic behavior derives from the strong magnetoelastic coupling of the manganese layers in this compound. PMID:23745927

  11. Friction welding of TiAl intermetallic compound

    Microsoft Academic Search

    T. Shinoda; K. Ito; C. Hayashi

    1997-01-01

    Recent years have seen TiAl intermetallic alloy attracting research interest as a high specific strength intermetallic compound. Practical applications of TiAl, however, are complicated by the fact that the material shows little ductility at temperatures below 1000 K, features poor plastic workability even at temperatures above 1200 K, to say nothing of its performance at normal temperature, and cannot be

  12. Formation of submicrocrystalline structure in TiAl intermetallic compound

    Microsoft Academic Search

    R. M. Imayev; V. M. Imayev; G. A. Salishchev

    1992-01-01

    The TiAl intermetallic compound was used to illustrate an approach which enables the creation of a submicrocrystalline structure (d?0.1 µm) in massive semifinished products made of hard-to-deform materials by means of their deformation at elevated temperatures. Tensile mechanical properties of the TiAl intermetallic compound with a mean grain size of 0.4 µm were tested. In this state, the lower temperature

  13. First-principles studies of Ni-Ta intermetallic compounds

    SciTech Connect

    Zhou Yi [Department of Materials Science and Engineering, College of Materials, and Research Center of Materials Design and Applications, Xiamen University, Xiamen 361005 (China); Wen Bin, E-mail: wenbin@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Ma Yunqing [Department of Materials Science and Engineering, College of Materials, and Research Center of Materials Design and Applications, Xiamen University, Xiamen 361005 (China); Melnik, Roderick [M2NeT Lab, Wilfrid Laurier University, Waterloo,75 University Ave. West, Ontario, N2L 3C5 (Canada); MIT Department, University of Jyvaeskylae, Jyvaeskylae (Finland); Liu Xingjun, E-mail: lxj@xmu.edu.cn [Department of Materials Science and Engineering, College of Materials, and Research Center of Materials Design and Applications, Xiamen University, Xiamen 361005 (China)

    2012-03-15

    The structural properties, heats of formation, elastic properties, and electronic structures of Ni-Ta intermetallic compounds are investigated in detail based on density functional theory. Our results indicate that all Ni-Ta intermetallic compounds calculated here are mechanically stable except for P21/m-Ni{sub 3}Ta and hc-NiTa{sub 2}. Furthermore, we found that Pmmn-Ni{sub 3}Ta is the ground state stable phase of Ni{sub 3}Ta polymorphs. The polycrystalline elastic modulus has been deduced by using the Voigt-Reuss-Hill approximation. All Ni-Ta intermetallic compounds in our study, except for NiTa, are ductile materials by corresponding G/K values and poisson's ratio. The calculated heats of formation demonstrated that Ni{sub 2}Ta are thermodynamically unstable. Our results also indicated that all Ni-Ta intermetallic compounds analyzed here are conductors. The density of state demonstrated the structure stability increases with the Ta concentration. - Graphical abstract: Mechanical properties and formation heats of Ni-Ta intermetallic compounds are discussed in detail in this paper. Highlights: Black-Right-Pointing-Pointer Ni-Ta intermetallic compounds are investigated by first principle calculations. Black-Right-Pointing-Pointer P21/m-Ni{sub 3}Ta and hc-NiTa{sub 2} are mechanically unstable phases. Black-Right-Pointing-Pointer Pmmn-Ni{sub 3}Ta is ground stable phase of Ni{sub 3}Ta polymorphs. Black-Right-Pointing-Pointer All Ni-Ta intermetallic compounds are conducting materials.

  14. First-principles studies of NiTa intermetallic compounds , Bin Wen b,n

    E-print Network

    Melnik, Roderick

    properties, and electronic structures of Ni­Ta intermetallic compounds are investigated in detail basedFirst-principles studies of Ni­Ta intermetallic compounds Yi Zhou a , Bin Wen b,n , Yunqing Ma Available online 10 January 2012 Keywords: Intermetallics Miscellaneous Crystal chemistry of intermetallics

  15. Factors Determining the Average Atomic Volumes in Intermetallic Compounds

    Microsoft Academic Search

    Linus Pauling

    1987-01-01

    In formation of an intermetallic compound from the elementary metals there is usually a contraction in volume. Electron transfer leading to the charge states M+ and M- with increase in valence and decrease in volume explains the more than 2-fold range in contraction for different compounds in the same binary system. In a more thorough analysis, the better packing of

  16. Electronic Band Structures of Intermetallic Compound Cu2Sb

    Microsoft Academic Search

    Tadaei Ito; Masafumi Shirai; Kazuko Motizuki

    1992-01-01

    Self-consistent APW band calculations are carried out for Cu2Sb intermetallic compound with Cu2Sb-type structure. The energy dispersion, density of states and Fermi surface are shown. Differences and similarities of the electronic band structures between Cu2Sb and other Cu2Sb-type compounds are clarified.

  17. Specific heat of R Ni 4 Al intermetallic compounds

    Microsoft Academic Search

    P. Svoboda; J. Vejpravová; S. Danis; M. Mihalik

    2006-01-01

    Here we present the detailed analysis of the specific heat data of selected intermetallic compounds RNi4Al for R=Ce,Pr,Nd, and Dy. To determine the magnetic entropy of these compounds, the zero-field specific heat data were measured in the temperature range 2–300K. The data of magnetic RNi4Al compounds were compared to those of non-magnetic isostructural analogues LaNi4Al, LaNi5 and YNi5 compounds to

  18. Nanomechanics of Mg–Al intermetallic compounds

    Microsoft Academic Search

    M.-X. Zhang; H. Huang; K. Spencer; Y.-N. Shi

    2010-01-01

    Cold spraying of pure Al powder on a pure Mg substrate together with subsequent post-spray annealing treatment produced Mg17Al12 (?-phase) and Mg2Al3 (?-phase) intermetallic layers on the surface of the substrate. These layers showed significantly better nanomechanical properties, including the reduced elastic modulus and nanohardness, which were determined using nanoindentation, than commercial purity Mg and AZ91 alloys. Combined with their

  19. Analysis of valence electron structures (VES) of intermetallic Fe 3Al compounds

    Microsoft Academic Search

    Yin Yansheng; Wang Wen Xiang; Shi Zhongliang

    1995-01-01

    Based on the empirical electron theory of solids and molecules, analysis of valence electron structures is made on Fe3Al intermetallic compounds. The bonding complex model of the DO3 cell is set up. Some preliminary attempts to discover the relationship between alloy composition, structure and properties and the Fe3Al alloy phase valence electron structure are presented.

  20. Synthesis and characterization of nanocrystalline binary and ternary intermetallic compounds

    E-print Network

    Leonard, Brian Matthew

    2009-05-15

    of Sn(II) to Sn(IV) (as a SnO2 shell), (2) formation of NiAs-type AuSn along with Cu and Sn nanoparticles using NaBH4 reduction, (3) aggregation and thermal interdiffusion to form a ternary alloy, and (4) nucleation of the ordered intermetallic compound...

  1. Synthesis and characterization of nanocrystalline binary and ternary intermetallic compounds 

    E-print Network

    Leonard, Brian Matthew

    2009-05-15

    nanocrystalline powders. Using this process, I was able to access several binary and ternary intermetallics, including two new phases: AuCuSn2 and AuNiSn2. These compounds were isolated as nanocrystals using low temperature solution synthesis techniques, which had...

  2. Structural and physical properties of the new intermetallic compound P. Solokha a

    E-print Network

    Ryan, Dominic

    Structural and physical properties of the new intermetallic compound Yb3Pd2Sn2 P. Solokha a , I t The crystal structure of the ternary intermetallic compound Yb3Pd2Sn2 has been determined ab initio from between this structure and those of Eu3Pd2Sn2 and Ca3Pd2Sn2, other novel polar intermetallic compounds

  3. Magnetostriction and magnetic anisotropy in rare earth intermetallic compounds

    Microsoft Academic Search

    M. R. Ibarra; A. del Moral

    1990-01-01

    An analysis of the magnetoelastic coupling and the magnetocrystalline anisotropy in rare earth intermetallic compounds has been undertaken on the basis of a microscopic description. Crystal electric field and exchange interaction have been considered as the main contribution to the free energy in order to explain the behaviour. Magnetostriction measurements on cubic (RAl2, RNi2) and uniaxial (RCo5 and R2Fe14B) compounds

  4. Fundamentals of mechanical behavior in intermetallic compounds

    SciTech Connect

    Fu, C.L.; Yoo, M.H.

    1991-01-01

    The fundamental aspects of deformation and fracture behavior of ordered intermetallics were investigated on the basis of quantum mechanical total-energy calculations and anisotropic elasticity theory for dislocations and cracks. These first-principles calculations were based on the local-density functional (LDF) theory. The LDF equations are solved either by full-potential linearized augmented plane-wave (FLAPW) method or by mixed-basis pseudopotential method. Our approach represents a major advance in applying LDF to solids, in which the LDF equations are solved without any shape approximation to the potential or change density and a high degree of variational freedom (and precision) can be achieved. The calculated elastic constants, various shear fault energies, defect self-energies, and cleavage energies were used in conjunction with the continuum modeling of dislocations and cracks to predict the mechanical behavior and to understand the underlying electronic mechanism of observed mechanical properties. 14 refs., 6 figs., 3 tabs.

  5. Investigation of the Effects of Ni, Fe, and Mn on the Formation of Complex Intermetallic Compounds in Al-Si-Cu-Mg-Ni Alloys

    NASA Astrophysics Data System (ADS)

    Gholizadeh, R.; Shabestari, S. G.

    2011-11-01

    The aim of this work is to partially substitute Fe and Mn for Ni in the 3HA piston alloy and to study the consequences through microstructural evaluation and the thermal analysis technique. Three types of near-eutectic alloys containing (2.6 wt pct Ni-0.2 wt pct Fe-0.1 wt pct Mn), (1.8 wt pct Ni-0.75 wt pct Fe-0.3 wt pct Mn), and (1 wt pct Ni-1.15 wt pct Fe-0.6 wt pct Mn) were produced, and their solidification was studied at the cooling rate of 0.9 K/s (°C/s) using the computer-aided thermal analysis technique. Optical microscopy and scanning electron microscopy were used to study the microstructure of the samples, and energy dispersive X-ray (EDX) analysis was used to identify the composition of the phases. Also, the quantity of the phases was measured using the image analysis technique. The results show that Ni mainly participates as Al3Ni, Al9FeNi, and Al3CuNi phases in the high Ni-containing alloy (2.6 wt pct Ni). In addition, substitution of Ni by Fe and Mn makes Al9FeNi the only Ni-rich phase, and Al12(Fe,Mn)3Si2 appears as an important Fe-rich intermetallic compound in the alloys with the higher Fe and Mn contents.

  6. Theory of the thermoelectricity of intermetallic compounds with Ce or Yb ions and R. Monnier2

    E-print Network

    Freericks, Jim

    Theory of the thermoelectricity of intermetallic compounds with Ce or Yb ions V. Zlati1 and R received 19 January 2005; published 14 April 2005 The thermoelectric properties of intermetallic compounds The thermoelectric power S T of intermetallic com- pounds with cerium and ytterbium ions exhibits some char

  7. Magnetism and superconductivity of uranium and intermetallic compounds

    SciTech Connect

    Cooley, J. C. (Jason C.); Gay, E. C. (Eddie C.); Hanrahan, R. J. (Robert J.); Hults, W. L. (William L.); Lashley, J. C. (Jason C.); Manley, M. E. (Michael E.); McPheeters, C. C. (Charles C.); Schmiedeshoff, G. M. (George M.); Thoma, D. J. (Dan J.); Touton, S. (Sharon); Smith, J. L. (James L.)

    2001-01-01

    Heat capacity, resistivity, and phonon density of states have been measured on uranium and reported already. Many of the results are on single crystals of purity that has been unavailable before. Some intermetallic compounds have been measured that are in the class of so-called heavy-fermion materials. We present here the latest results along with a discussion of the occurrence of superconductivity or magnetism in these materials.

  8. Applying TLP bonding to the joining of structural intermetallic compounds

    Microsoft Academic Search

    William F. Gale

    1999-01-01

    Transient-liquid-phase bonding provides a method of joining nonweldable materials intended for elevated temperature service.\\u000a This paper discusses the mechanisms of transient-liquid-phase bonding as a reactive liquid process for the joining of structural\\u000a intermetallic compounds. The importance of alloying reactions for successful wetting of the substrates by the liquid interlayer\\u000a is stressed, and the roles of dissolution, isothermal solidification, and homogenization

  9. Magnetic Anisotropy of New Intermetallic Compound SmFe7

    Microsoft Academic Search

    Hiroaki Samata; Nobuto Fujiwara; Yujiro Nagata; Takayuki Uchida; Ming Der Lan

    1998-01-01

    We characterized the magnetocrystalline anisotropy of a novel intermetallic compound, SmFe7, by means of torque measurement. Single crystal of SmFe7 was grown by the self-flux method using Sm as a flux. From an analysis of the torque curves in the (001) and (100) planes using the least mean squares method, we found that the tetragonal anisotropy constants K1, K2 and

  10. Magnetostriction and magnetic anisotropy in rare earth intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Ibarra, M. R.; del Moral, A.

    1990-01-01

    An analysis of the magnetoelastic coupling and the magnetocrystalline anisotropy in rare earth intermetallic compounds has been undertaken on the basis of a microscopic description. Crystal electric field and exchange interaction have been considered as the main contribution to the free energy in order to explain the behaviour. Magnetostriction measurements on cubic (RAl 2, RNi 2) and uniaxial (RCo 5 and R 2Fe 14B) compounds are reported. A single ion origin for the magnetocristalline anisotropy of the R 3+ ion has been tested, which has allowed a complete and reliable description of the spin reorientation processes because of the interplay of competing anisotropies.

  11. The Shock Hugoniot of the Intermetallic Compound Ni3Al

    SciTech Connect

    Knapp, I.; Millett, J. C. F.; Meziere, Y. J. E. [Defence Academy of the United Kingdom, Cranfield University, Shrivenham, Swindon, SN6 8LA (United Kingdom); Gray, G. T. III [Los Alamos National Laboratory, Los Alamos, New Mexico, 87545 (United States); Bourne, N. K. [University of Manchester, Sackville Street, Manchester, M60 1QD (United Kingdom)

    2006-07-28

    The behaviour of the intermetallic compound, Ni3Al under shock loading conditions has been measured. The Hugoniot Elastic Limit occurs at ca. 530 MPa, which converts to a 1-D yield stress of 273 MPa, in agreement with quasi-static data. In contrast, the ductility at shock-induced strain-rates appears much reduced when compared to lower strain-rates. The Hugoniot in terms of shock velocity and particle velocity suggests that Ni3Al is more compressible than pure nickel. This is in agreement with the greater stiffnesses in nickel, measured using ultrasonic techniques.

  12. The Shock Hugoniot of the Intermetallic Compound Ni3Al

    NASA Astrophysics Data System (ADS)

    Knapp, I.; Millett, J. C. F.; Gray, G. T.; Bourne, N. K.; Meziere, Y. J. E.

    2006-07-01

    The behaviour of the intermetallic compound, Ni3Al under shock loading conditions has been measured. The Hugoniot Elastic Limit occurs at ca. 530 MPa, which converts to a 1-D yield stress of 273 MPa, in agreement with quasi-static data. In contrast, the ductility at shock-induced strain-rates appears much reduced when compared to lower strain-rates. The Hugoniot in terms of shock velocity and particle velocity suggests that Ni3Al is more compressible than pure nickel. This is in agreement with the greater stiffnesses in nickel, measured using ultrasonic techniques.

  13. Structural properties of intermetallic Li-Be compound

    NASA Astrophysics Data System (ADS)

    Galav, K. L.; Paliwal, U.; Joshi, K. B.

    2012-06-01

    We present the structural properties of binary intermetallic compound Li-Be crystallizing in the space group P21/m. We have performed first-principles calculations employing both generalized gradient approximation (GGA) and local density approximation (LDA) within Density Functional Theory (DFT). The calculations are performed using CRYSTAL98 code. Here we obtain the zero-temperature bulk modulus, lattice constant and pressure derivative of bulk modulus by fitting the Murnaghan equation of state. We also present structure factors at a few (hkl) values using both GGA and LDA.

  14. Erosion behavior and structure of silver-intermetallic compound electrical contact materials

    Microsoft Academic Search

    N. L. Pravoverov; M. P. Afonin; A. K. Dorozhkin; I. M. Lobyntseva

    1980-01-01

    The action of an arc discharge on a contact made of a silver-intermetallic compound composite material is accompanied by selective erosion in the affected zone, which is a result of the anchoring of the arc discharge to particles of the intermetallic compound — a phase of comparatively low thermal conductivity. A characteristic feature of the selective erosion is a nonuniform

  15. Microstructures and defect structures in intermetallic compounds in the La–Ni alloy system

    Microsoft Academic Search

    H Inui; T Yamamoto; Zhang Di; M Yamaguchi

    1999-01-01

    Microstructures and defect structures in intermetallic compounds in the La–Ni alloy system have been investigated by transmission electron microscopy in the composition range of La–77.8?83.2 at.%Ni, which corresponds to compositions between two intermetallic phases, La2Ni7 and LaNi5. The intermetallic phase, La5Ni19 of the Ce5Co19-type is found for the first time to exist as an equilibrium phase at a composition between

  16. Sublimation thermodynamics of the PuRu 2 intermetallic compound

    NASA Astrophysics Data System (ADS)

    Peterson, Dean E.

    1980-07-01

    The sublimation behavior of the PuRu 2 intermetallic compound has been characterized by concurrent target collection and mass spectrometric measurements. The compound was shown to undergo dissociative sublimation to form gaseous Pu and solid Ru metal. Vapor pressures of Pu(g) in equilibrium with PuRu 2(s) were determined by the Knudsen effusion technique over the temperature range 1503-1778 K. The standard enthalpy and entropy of sublimation calculated at 1640 K by a second law analysis were 477 ± 19 kJ/mol and 126 ± 12 J/K · mol, respectively. The ?H of and ?S of determined for formation of PuRu 2(s) at 1640 K were -147 ± 23 kJ/mol and -34 ± 13 J/K · mol, respectively. A third law analysis of the vapor pressures with estimated Gibbs' free energy functions yielded enthalpies of sublimation and formation at 298 K of 472 ± 2 and -124 ± 6 kJ/mol, respectively.

  17. First-principle studies of CaX (X=Si,Ge,Sn,Pb) intermetallic compounds Zhiwen Yang a

    E-print Network

    Melnik, Roderick

    November 2009 Keywords: Intermetallics Band structures Elastic properties Heats of formation First structures, and densities of states of 20 intermetallic compounds in the Ca­X (X=Si, Ge, Sn, Pb) systems have intermetallic compounds. In this paper, the structural properties, elastic properties, mechanical stability

  18. X (X: Al, Mo, Ti, Pt, Si, Nb, V, and Zr) intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Chen, Qiang; Huang, Zhiwei; Zhao, Zude; Hu, Chuankai

    2014-09-01

    In the present study, the ground-state properties of Ni3X intermetallic compounds were analyzed by means of the first-principles pseudo-potential method using the Cambridge serial total energy package code. The calculated lattice parameters of Ni3X intermetallic compounds are in good agreement with the experimental and other theoretical data. The single-crystal elastic constants were calculated; the hardness, ductile, and plasticity of materials were analyzed. The calculated enthalpies of formation showed that all of intermetallic compounds were thermodynamically stable; Debye temperature and heat capacity are calculated and discussed. Moreover, the chemical bonding in these intermetallic compounds was interpreted by calculating the density of states, electron density difference distribution, and Mulliken analysis; magnetism properties were briefly analyzed.

  19. Intermetallic compound formation at Cu-Al wire bond interface

    SciTech Connect

    Bae, In-Tae; Young Jung, Dae [Small Scale Systems Integration and Packaging Center, State University of New York at Binghamton, Binghamton, New York 13902 (United States); Chen, William T.; Du Yong [Advanced Semiconductor Engineering Inc., 1255 E Arques Ave, Sunnyvale, California 94085 (United States)

    2012-12-15

    Intermetallic compound (IMC) formation and evolution at Cu-Al wire bond interface were studied using focused ion beam /scanning electron microscopy, transmission electron microscopy (TEM)/energy dispersive x-ray spectroscopy (EDS), nano beam electron diffraction (NBED) and structure factor (SF) calculation. It was found that discrete IMC patches were formed at the Cu/Al interface in as-packaged state and they grew toward Al pad after high temperature storage (HTS) environment at 150 Degree-Sign C. TEM/EDS and NBED results combined with SF calculation revealed the evidence of metastable {theta} Prime -CuAl{sub 2} IMC phase (tetragonal, space group: I4m2, a = 0.404 nm, c= 0.580 nm) formed at Cu/Al interfaces in both of the as-packaged and the post-HTS samples. Two feasible mechanisms for the formation of the metastable {theta} Prime -CuAl{sub 2} phase are discussed based on (1) non-equilibrium cooling of wire bond that is attributed to highly short bonding process time and (2) the epitaxial relationships between Cu and {theta} Prime -CuAl{sub 2}, which can minimize lattice mismatch for {theta} Prime -CuAl{sub 2} to grow on Cu.

  20. Combustion synthesis of TiNi intermetallic compounds

    SciTech Connect

    Depiak, A.; Depiak, K.; Wierzba, I.; Karim, G.A. [Univ. of Calgary, Alberta (Canada). Dept. of Mechanical Engineering

    1996-10-01

    The technique, self-propagating high temperature synthesis (SHS) was used to produce TiNi intermetallic compounds. The reactants in the form of a compacted powder pellet were ignited in a thermal explosion mode. Microstructural observations of SHS-reacted pellets established that the combustion in air, argon or vacuum of a stoichiometric mixture of Ti and Ni powders resulted mainly in the TiNi parent phase. Some phase disparities occurred when the synthesis was carried out in air, particularly in the vicinity of the surface of the pellet. As a result of the preferential formation of TiO{sub 2} near the surface, it was observed that an intermediate product region was composed of the eutectic structure of TiNi + TiNi{sub 3}. It was observed that the ignition temperature in air was lower than that recorded for the argon and vacuum atmospheres. Through microstructural analysis it is concluded that this can be attributed to the formation of TiO{sub 2} on the surface of the pellet. This oxidation, exothermic in nature, stimulated the Ti + Ni reaction. Application is for hydrogen storage and transport applications.

  1. Use of high magnetic fields at the study of magnetism and superconductivity in intermetallic compounds

    Microsoft Academic Search

    J. J. M. Franse; F. R. Deboer; P. H. Frings; A. Devisser

    1994-01-01

    Magnetic fields have a large impact on the magnetic and superconducting properties of solids. High magnetic fields are required to reach magnetic saturation along a hard magnetic direction in a variety of rare-earth intermetallics, to break the ferrimagnetic moment configuration in specific 3d-4f intermetallics, to quench the strongly correlated electron states in heavy-fermion compounds, to reach the upper critical fields

  2. The use of high magnetic fields for the study of magnetism and superconductivity in intermetallic compounds

    Microsoft Academic Search

    J. J. M. Franse; F. R. De Boer; P. H. Frings; A. De Visser

    1994-01-01

    Magnetic fields have a large impact on the magnetic and superconducting properties of solids. High magnetic fields are required to reach magnetic saturation along a hard magnetic direction in a variety of rare-earth intermetallics, to break the ferrimagnetic moment configuration in specific 3d-4f intermetallics, to quench the strongly correlated electron states in heavy-fermion compounds, to reach the upper critical fields

  3. The role of intermetallic compounds in lead-free soldering

    Microsoft Academic Search

    Paul G. Harris; Kaldev S. Chaggar

    1998-01-01

    The role of intermetallics in soldered joints is ambivalent. They are an essential part of joints to common basis materials and at low levels they have a strengthening effect on solder alloys. At higher levels, however, it is well known that they can cause joint embrittlement. In this paper three aspects of their role have been studied: the microstructure of

  4. Magnetic properties of intermetallic compound Pr2NiSi3

    NASA Astrophysics Data System (ADS)

    Pakhira, Santanu; Mazumdar, Chandan; Ranganathan, R.

    2015-06-01

    We report here the synthesis and basic magnetic properties of a intermetallic compound Pr2NiSi3. The compound crystallizes in hexagonal AlB2 type crystal structure with space group P6/mmm. The compound orders antiferromagnetically below 2.6 K with a positive paramagnetic Curie temperature. Along with antiferromagnetic ordering experimental signature for presence of ferromagnetic interaction has also been observed for this compound.

  5. Use of combustion and thermal explosion for the synthesis of intermetallic compounds and their alloys

    Microsoft Academic Search

    V. I. Itin; A. D. Bratchikov; L. N. Postnikova

    1980-01-01

    Methods of utilizing the heat evolving during reactions between components for the synthesis of intermetallic compounds and their alloys may vary depending on the character of the exothermic processes occurring in the metal powder mixtures employed. During the initiation of a reaction in some local volume of a substance heat is liberated in the reaction zone. This raises the temperature

  6. Reliability studies of surface mount solder joints - effect of Cu-Sn intermetallic compounds

    Microsoft Academic Search

    Alex C. K. So; Yan C. Chan

    1996-01-01

    Cu-Sn intermetallic compounds (IMCs), formed at the interface between the solder and the copper substrate are found to play a dominant role in determining the thermal fatigue life of surface mount solder joints fabricated from a conventional infrared reflow process. In order to predict the growth of this IMC layer during the operating life of the solder joint and its

  7. Determination of Charge Component Composition in Self-Propagating High-Temperature Synthesis of Intermetallic Compounds

    Microsoft Academic Search

    A. T. Evtushenko; O. A. Lebedeva; S. S. Torbunov

    2005-01-01

    A method for determining the component composition of the charge for the self-propagating high-temperature synthesis of intermetallic compounds from the maximum value of the emitted heat in the combustion of thermit, which is required for melting the alloying components, is suggested. The mass composition of the alloying components is determined by solving a closed system of algebraic equations represented by

  8. Resonant ultrasound spectroscopy: Elastic properties of some intermetallic compounds

    SciTech Connect

    Chu, F.; Thoma, D.J.; He, Y.; Maloy, S.A.; Mitchell, T.E. [Los Alamos National Lab., NM (United States). Materials Science Technology Div.

    1996-09-01

    A novel nondestructive evaluation method, resonant ultrasound spectroscopy (RUS), is reviewed with an emphasis upon defining the elastic properties of intermetallic phases. The applications and advantages of RUS as compared to other conventional elastic constant measurement methods are explained. RUS has been employed to measure the elastic properties of single crystal and/or polycrystalline intermetallics, such as Laves phases (C15 HfV{sub 2} and NbCr{sub 2}), Nb-modified titanium aluminides, and transition metal disilicides (C11{sub b} MoSi{sub 2}, C40 NbSi{sub 2} and TaSi{sub 2}). For Laves phases, the elastic properties of HfV{sub 2}-based C15 phases show various anomalies and those of C15 NbCr{sub 2} do not. For Nb-modified titanium aluminides, the elastic properties of O-phase alloys are investigated as a function of alloying content. For transition metal disilicides, single crystal elastic constants of MoSi{sub 2}, NbSi{sub 2}, and TaSi{sub 2} are obtained and compared. Based on the experimentally determined elastic properties, the characteristics of interatomic bonding in these materials are examined and the possible impact of the elastic properties on mechanical behavior is discussed.

  9. Oxygen reduction on supported Pt alloys and intermetallic compounds in phosphoric acid. Final report

    SciTech Connect

    Ross, P.N. Jr.

    1980-09-01

    A strong d-orbital interaction between Pt and any of the Group IVb and Group Vb metals is expected from the Engel-Brewer valence bond model. A ligand modification of the electrocatalytic properties of Pt in Pt-Group IV-Vb intermetallic compounds is reported. All the intermetallics studied were single phase bimetallic clusters well dispersed (30 to 50A) on Vulcan XC-72 carbon black with a Pt to base metal ratio varying between 3:1 and 5:1. All had a fcc structure of the Cu/sub 3/Au type. Neither hydrogen nor carbon monoxide was chemisorbed on the reduced catalyst at 273 K. Stability tests in H/sub 3/PO/sub 4/ at 450 K indicated these intermetallics were not decomposed on a 10/sup 2/ h time scale, although some dissolution of base metal from the surface of the clusters seems probable. Oxygen reduction kinetics were measured using flooded thin layer electrodes and Teflonbonded fuel cell type electrodes. The results for ambient pressure fuel cell conditions indicated the Pt intermetallics are significantly more active than pure Pt. The difference in Tafel slope and activation energy for the intermetallics indicates the reaction is probably via the same pathway as on pure Pt but via adsorbed intermediates with a lower heat of adsorption and with a different potential dependence. At acid concentrations with higher free water contents than typical for ambient pressure cells, the difference between pure Pt and the Pt intermetallics was even greater due to the lower heat of formation of oxygenated intermediates on Pt in the intermetallic. This enhanced catalysis was demonstrated in Teflon-bonded fuel cell type electrodes. In 0.5 mg/cm/sup 2/ electrodes of optimized structure, the expected performance gains for ambient air consumption at 200 ASF should be 20 to 40 mV over conventional supported Pt catalyst.

  10. Influence of hydrogenation on magnetic interactions in intermetallic RNi (R = Gd, Tb, Dy) compounds

    Microsoft Academic Search

    W. Iwasieczko; H. Drulis; Yu. L. Yaropolov; S. A. Nikitin; V. N. Verbetsky

    2011-01-01

    The influence of hydrogenation on the magnetic properties of intermetallic compound RNi is reported. GdNiH3.2, TbNiH3.4, DyNiH3.4 hydrides have been synthesized and their magnetic properties were investigated in the temperature range 1.8–300K. It was established that hydrogen absorption in these compounds makes the ferro- and antiferromagnetic interactions between magnetic moments much weaker. The reasons of this phenomenon are discussed. The

  11. Augmented-Plane-Wave Calculations of the Electronic Structure of Intermetallic Compounds YCu and YZn

    Microsoft Academic Search

    M. Belakhovskii; J. Pierre; D. K. Ray

    1972-01-01

    In order to understand the electronic structure of the rare-earth intermetallic compounds RX, where X=Cu, Ag, Au or Zn, Cd and R is a rare-earth element, the energy bands of the isomorphous compounds YCu and YZn have been calculated by the augmented-plane-wave method along different symmetry directions. The calculated Fermi energies for YCu and YZn are +0.42 and +0.47 Ry,

  12. Electronic properties of HffXY intermetallic compounds (X =Si, Ge; Y =S, Se, Te)

    Microsoft Academic Search

    I. Yaar; I. Halevy; S. Kahane; A. Beck; Z. Berant

    2008-01-01

    The electric field gradient (efg) parameters were calculated for the ternary system HfXY (X =Si, Ge; Y =S, Se, Te), using the full-potential linear augmented plane wave (LAPW) method applying the generalized gradient approximation (GGA). The major contribution to the efg value in these compounds comes from the p-p contribution next to the probe nucleus. The intermetallic compounds HfXY (X

  13. Electronic properties of Hf XY intermetallic compounds ( X = Si, Ge; Y = S, Se, Te)

    Microsoft Academic Search

    I. Yaar; I. Halevy; S. Kahane; A. Beck; Z. Berant

    2007-01-01

    The electric field gradient (efg) parameters were calculated for the ternary system HfXY (X = Si, Ge; Y = S, Se, Te), using the full-potential linear augmented plane wave (LAPW) method applying the generalized gradient approximation\\u000a (GGA). The major contribution to the efg value in these compounds comes from the p-p contribution next to the probe nucleus.\\u000a The intermetallic compounds

  14. First-principle studies of Ca-X (X=Si,Ge,Sn,Pb) intermetallic compounds

    SciTech Connect

    Yang Zhiwen; Shi Dongmin [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116023 (China); Wen Bin, E-mail: wenbin@dlut.edu.c [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116023 (China); Melnik, Roderick [M2NeT Lab, Wilfrid Laurier University, Waterloo, 75 University Ave. West, Ontario, N2L3C5 (Canada); Yao Shan; Li Tingju [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116023 (China)

    2010-01-15

    The structural properties, elastic properties, heats of formation, electronic structures, and densities of states of 20 intermetallic compounds in the Ca-X (X=Si, Ge, Sn, Pb) systems have been systematically investigated by using first-principle calculations. Our computational results indicated that with increasing atomic weight of X, the bulk modulus of Ca-X intermetallic compounds decreases gradually. It was also found that Ca{sub 36}Sn{sub 23} and CaPb are mechanically unstable phases. Results on the electronic energy band and densities of states also indicated that Ca{sub 3}Si{sub 4} is an indirect band gap semiconductor with a band gap of 0.598 eV, and Ca{sub 2}Si, Ca{sub 2}Ge, Ca{sub 2}Sn, and Ca{sub 2}Pb are direct band gap semiconductors with band gaps of 0.324, 0.265, 0.06, and 0.07 eV, respectively. In addition, it is found that the absolute values of heats of formation for all Ca-X intermetallics are larger than 30 kJ/mol atom. - Graphical abstract: Calculated (a) bulk moduli and (b) shear moduli of Ca-X system intermetallic compounds.

  15. Pseudogap Formation in the Intermetallic Compounds \\(Fe1-xVx\\)3Al

    NASA Astrophysics Data System (ADS)

    Okamura, H.; Kawahara, J.; Nanba, T.; Kimura, S.; Soda, K.; Mizutani, U.; Nishino, Y.; Kato, M.; Shimoyama, I.; Miura, H.; Fukui, K.; Nakagawa, K.; Nakagawa, H.; Kinoshita, T.

    2000-04-01

    Optical conductivity data of the intermetallic compounds \\(Fe1-xVx\\)3Al ( 0<=x<=0.33) reveal that their density of states around the Fermi energy ( EF) is strongly reduced as x is increased. In particular, Fe2VAl ( x = 0.33) has a deep, well-developed pseudogap of 0.1-0.2 eV at EF and a small density ( ~5×1020 cm-3) of carriers, which is highly unusual for intermetallic compounds. It is shown that the pseudogap results from the band structure of Fe2VAl, rather than from temperature-dependent correlation effects. Based on the present results, we propose a simple model that consistently explains both the semiconductorlike transport and the metallic photoemission results previously observed for Fe2VAl.

  16. Pseudogap formation in the intermetallic compounds (Fe1-xVx)3Al

    PubMed

    Okamura; Kawahara; Nanba; Kimura; Soda; Mizutani; Nishino; Kato; Shimoyama; Miura; Fukui; Nakagawa; Nakagawa; Kinoshita

    2000-04-17

    Optical conductivity data of the intermetallic compounds (Fe1-xVx)3Al ( 0intermetallic compounds. It is shown that the pseudogap results from the band structure of Fe2VAl, rather than from temperature-dependent correlation effects. Based on the present results, we propose a simple model that consistently explains both the semiconductorlike transport and the metallic photoemission results previously observed for Fe2VAl. PMID:11019174

  17. Microscopic evidence for magnetic-phase coexistence in the intermetallic compound Nd7Rh3

    NASA Astrophysics Data System (ADS)

    Rayaprol, S.; Siruguri, V.; Hoser, A.; Ritter, C.; Sampathkumaran, E. V.

    2014-10-01

    The intermetallic compound Nd7Rh3, which shows two magnetic transitions, one at 32 K and another around 16 K, has been known to exhibit a magnetic-field induced first-order magnetic phase transition (FOPT) at low temperatures. Using neutron diffraction we tracked the evolution of the magnetic features as a function of temperature and external magnetic field across the two transition temperatures. We provide evidence for the existence of both antiferromagnetism and ferromagnetism below 20 K. Notably the results reveal concrete evidence for the partial persistence of the high-field magnetic state at 2 K after cycling through the magnetic-field-induced magnetic transition, thereby offering microscopic evidence for magnetic coexistence phenomenon in this intermetallic compound.

  18. Intermetallic compound layer growth kinetics in non-lead bearing solders

    SciTech Connect

    Vianco, P.T.; Kilgo, A.C.; Grant, R.

    1995-04-01

    The introduction of alternative, non-lead bearing solders into electronic assemblies requires a thorough investigation of product manufacturability and reliability. Both of these attributes can be impacted by the excessive growth of intermetallic compound (IMC) layers at the solder/substrate interface. An extensive study has documented the stoichiometry and solid state growth kinetics of IMC layers formed between copper and the lead-free solders: 96.5Sn-3.5Ag (wt.%), 95Sn-5Sb, 100Sn, and 58Bi-42Sn. Aging temperatures were 70--205 C for the Sn-based solders and 55--120 C for the Bi-rich solder. Time periods were 1--400 days for all of the alloys. The Sn/Cu, Sn-Ag/Cu, and Sn-Sb/Cu IMC layers exhibited sub-layers of Cu{sub 6}Sn{sub 5} and Cu{sub 3}Sn; the latter composition was present only following prolonged aging times or higher temperatures. The total layer growth exhibited a time exponent of n = 0.5 at low temperatures and a value of n = 0.42 at higher temperatures in each of the solder/Cu systems. Similar growth kinetics were observed with the low temperature 58Bi-42Sn solder; however, a considerably more complex sub-layer structure was observed. The kinetic data will be discussed with respect to predicting IMC layer growth based upon solder composition.

  19. Modeling of interfacial intermetallic compounds in the application of very fine lead-free solder interconnections

    Microsoft Academic Search

    Zhiheng Huang; Paul P. Conway; Rongshan Qin

    2009-01-01

    Intermetallic compounds (IMCs) are formed between lead-free solders and base metals during soldering processes. The morphology\\u000a as well as the amount of the IMCs, in particular the interfacial IMCs, are important to mechanical performance of the solder\\u000a joints in their service environment. This is especially the case in state-of-art ultrafine-pitch wafer-level packaging, in\\u000a which solder joints could become as small

  20. Anomalous strain rate dependence of the flow stress in TiAl intermetallic compounds

    Microsoft Academic Search

    Dong Zhu; Liming Wang; Dunxu Zou; Mei Yao; Qigong Cai

    1992-01-01

    The anomalous increase in yield and flow strength with increasing temperature in certain intermetallic compounds is one of the outstanding issues in materials science. This anomaly was well explained for the L12 structure [1]. Yoo et al. [2] studied the plastic deformation of Ni3A1 and\\/3-CuZn alloys with L12 and B2 structures, respectively. In the medium temperature region the shear fault

  1. Combustion synthesis of Ni 3Al intermetallic compound in self-propagating mode

    Microsoft Academic Search

    C. L. Yeh; W. Y. Sung

    2004-01-01

    The production of Ni3Al intermetallic compound from elemental powder compacts was conducted by self-propagating high-temperature synthesis (SHS) in this study. Effects of initial sample density, preheating temperature, and particle size of the reactants on the combustion characteristics, as well as on the composition and morphology of final products were studied. Experimental observation indicated that the combustion process was preceded by

  2. Structural relationships in intermetallic compounds of the Al-Li-(Cu, Mg, Zn) system

    Microsoft Academic Search

    M. Audier; Ch. Janot; M. de Boissieu; B. Dubost

    1989-01-01

    Intermetallic compounds with compositions in the vicinity of Al0·6 (Cu, Zn), (Li, Mg)0·3, namely the so-called R, Z, C and ? phases, have been selected for structural studies because of their presumed relation with the Al-Cu-Li quasicrystal. Neutron diffraction data strongly suggest unicity for short- and medium-range arrangements in these phases. Transmission electron microscopy confirms the point and allows detailed

  3. Self-consistent electronic structure of the intermetallic compound LiA1

    Microsoft Academic Search

    T. Asada; T. Jarlborg; A. J. Freeman

    1981-01-01

    The electronic structure of the intermetallic compound LiA1, which has a B32 structure, has been studied by a self-consistent linear-muffin-tin-orbital method within the atomicsphere approximation and in the local-density formalism. The overall band structure and density of states have a reasonable resemblance with those obtained previously by Zunger, except for several important differences near the Fermi energy. Whereas our results

  4. Quenched-in vacancies in B2-structured intermetallic compound FeAl

    Microsoft Academic Search

    Mineo Kogachi; Tomohide Haraguchi

    1997-01-01

    The concentrations of quenched-in vacancies retained in B2 intermetallic compound Fe1-cAlc were obtained as functions of composition (0.39 < c < 0.51) and quenching temperature (773–1273 K) from lattice constant and density measurements. Obtained vacancy concentration indicates rather gradual increase with composition in lower Al content region, while it increased rapidly as the composition approaches to stoichiometric composition. Further, the

  5. Intermetallic compound layer growth at the interface between Sn–Cu–Ni solder and Cu substrate

    Microsoft Academic Search

    Jeong-Won Yoon; Young-Ho Lee; Dae-Gon Kim; Han-Byul Kang; Su-Jeong Suh; Cheol-Woong Yang; Chang-Bae Lee; Jong-Man Jung; Choong-Sik Yoo; Seung-Boo Jung

    2004-01-01

    Phase analysis and growth kinetics of intermetallic compound (IMC) layers formed between low cost Sn–Cu–Ni solder for wave soldering and Cu substrate by solid state isothermal aging were examined at temperatures between 80 and 150°C for 0 to 60 days. The IMC layer was composed of two phases; Cu6Sn5 (also (Cu,Ni)6Sn5) adjacent to the solder, Cu3Sn adjacent to the copper.

  6. Effects of Gas Pressure of Cold Spray on the Formation of Al-Based Intermetallic Compound

    NASA Astrophysics Data System (ADS)

    Lee, H.; Shin, H.; Ko, K.

    2010-01-01

    In this paper, postannealing of cold-sprayed (CDGS) coatings for intermetallic compounds (IMC) in the matrix at low temperature and dependences of types and dispersion characteristics of intermetallic compounds on spraying pressure condition were investigated. The pressure prior to entering the gas heater was fixed at 0.7, 1.5, and 2.5 MPa. The relatively soft Al has been coated at low gas pressure condition (0.7 MPa) with severe plastic deformation owing to large peening effect. On the contrary, the Al particles coated at the higher pressure (1.5, 2.5 MPa) were not severely deformed. It was concluded that the pressure-controlled peening effects could alter the main route of Al consumption during annealing: eutectic or compounding of intermetallics. The thin and continuous IMC layer was formed at the interface with low pressure condition (0.7 MPa). On the other hand, the thick and discontinuous IMC layer was observed at the higher pressure condition (1.5, 2.5 MPa). Also, many eutectic pores were found in the Al-Ni composite coatings with lower gas pressure condition (0.7 MPa), but far less were found with high pressure environment.

  7. Magnetic structure of the intermetallic compound DyAg

    Microsoft Academic Search

    T. Kaneko; H. Yoshida; M. Ohashi; S. Abe

    1987-01-01

    Neutron diffraction measurements were performed for an antiferromagnetic compound DyAg with TN=56.7 K. Magnetic structures were found to be the (pi pi 0)-type at 12 K and rthe sinusoidally modulated transverse static spin wave propagating along the direction and polarized in the direction at 50.7 K.

  8. Structural building principles of complex face-centered cubic intermetallics.

    PubMed

    Dshemuchadse, Julia; Jung, Daniel Y; Steurer, Walter

    2011-08-01

    Fundamental structural building principles are discussed for all 56 known intermetallic phases with approximately 400 or more atoms per unit cell and space-group symmetry F43m, Fd3m, Fd3, Fm3m or Fm3c. Despite fundamental differences in chemical composition, bonding and electronic band structure, their complex crystal structures show striking similarities indicating common building principles. We demonstrate that the structure-determining elements are flat and puckered atomic {110} layers stacked with periodicities 2p. The atoms on this set of layers, which intersect each other, form pentagon face-sharing endohedral fullerene-like clusters arranged in a face-centered cubic packing (f.c.c.). Due to their topological layer structure, all these crystal structures can be described as (p × p × p) = p(3)-fold superstructures of a common basic structure of the double-diamond type. The parameter p, with p = 3, 4, 7 or 11, is determined by the number of layers per repeat unit and the type of cluster packing, which in turn are controlled by chemical composition. PMID:21775807

  9. Crystal electric field in RAgSb{sub 2} (R = Ho, Er, Tm) intermetallic compounds

    SciTech Connect

    Sashin, I. L., E-mail: sashin@nf.jinr.ru; Goremychkin, E. A. [Joint Institute for Nuclear Research (Russian Federation); Szytula, A. [Jagiellonian University, Smoluchowski Institute of Physics (Poland); Clementyev, E. S. [Technical University of Munich (Germany)

    2007-05-15

    The magnetic scattering spectra of RAgSb{sub 2} (R = Ho, Er, Tm) intermetallic compounds are measured and their crystal electric field parameters are determined using inelastic neutron scattering. It is revealed that the ground state is a nonmagnetic singlet for the HoAgSb{sub 2} compound, a Kramers doublet with a strongly anisotropic g factor for the ErAgSb{sub 2} compound, and a quasi-doublet (random doublet) characterized by an extremely anisotropic g factor for the TmAgSb{sub 2} compound. The exchange interaction is estimated in the molecular field approximation. The magnetic properties of the RAgSb{sub 2} compounds are analyzed in terms of the energy level schemes and eigenfunctions determined in this study. The calculated anisotropic magnetic susceptibilities for all compounds are in good agreement with the experimental data obtained for single crystals.

  10. Massive spalling of intermetallic compounds in solder-substrate reactions due to limited supply of the active element

    SciTech Connect

    Yang, S. C.; Ho, C. E.; Chang, C. W.; Kao, C. R. [Department of Chemical and Materials Engineering, National Central University, Jhongli City, Taiwan (China); Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan (China)

    2007-04-15

    Massive spalling of intermetallic compounds has been reported in the literature for several solder/substrate systems, including SnAgCu soldered on Ni substrate, SnZn on Cu, high-Pb PbSn on Cu, and high-Pb PbSn on Ni. In this work, a unified thermodynamic argument is proposed to explain this rather unusual phenomenon. According to this argument, two necessary conditions must be met. The number one condition is that at least one of the reactive constituents of the solder must be present in a limited amount, and the second condition is that the soldering reaction has to be very sensitive to its concentration. With the growth of intermetallic, more and more atoms of this constituent are extracted out of the solder and incorporated into the intermetallic. As the concentration of this constituent decreases, the original intermetallic at the interface becomes a nonequilibrium phase, and the spalling of the original intermetallic occurs.

  11. Magnetic properties of the intermetallic compounds RNi (R=Gd, Tb, Dy, Sm) and their hydrides

    Microsoft Academic Search

    Yu. L. Yaropolov; V. N. Verbetsky; A. S. Andreenko; K. O. Berdyshev; S. A. Nikitin

    2010-01-01

    Hydrogen interaction with RNi intermetallic compounds and the influence of hydrogen on magnetic properties of these compounds\\u000a were investigated. Ternary hydrides GdNiH3.2, TbNiH3.4, DyNiH3.4 and SmNiH3.7 were prepared by hydrogenation of the initial alloys at room temperature and hydrogen pressure up to 0.1 MPa. Hydrides possess\\u000a orthorhombic CrB-type structure (S.G. Cmcm). The formation of hydrides results in substantial expansion of

  12. Low temperature properties of some Er-rich intermetallic compounds

    SciTech Connect

    K.A. Gshneidner,jr; A.O. Pecharsky; L.Hale; V.K. Pecharsky

    2004-09-30

    The low temperature volumetric heat capacity ({approx}3.5 to 350 K) and magnetic susceptibility ({approx}4 to 320 K) of Er{sub 3}Rh, Er{sub 3}Ir, Er{sub 3}Pt, Er{sub 2}Al, and Er{sub 2}Sn have been measured. All of the compounds order antiferromagnetically (or ferrimagnetically), and most exhibit more than one magnetic ordering transition. The volumetric heat capacities in general are smaller than those of the prototype magnetic regenerator materials, except for Er{sub 3}Ir in the 12 to 14 K temperature range.

  13. Long-Term Behavior of the Tritides Formed by Nickel-Based Intermetallic Compounds

    SciTech Connect

    Bowman, Jr., R. C.; Steinmeyer, R. H.; Matson, L. K.; Attalla, A.; Craft, B. D.

    1985-04-01

    Some properties of the tritide phases formed by the intermetallic compounds Mg2Ni, ZrNi, and LaNi5 have been studied. Whereas ZrNiT3 will retain its stoichiometry indefinitely when sufficient gaseous tritium is available, the stoichiometries of Mg2NiT4 and LaNi5T6.9 decrease with time. Although all three intermetallic tritides can retain large quantities of the helium-3 tritium decay daughter product in the solid phase, irreversible release of helium begins after several hundred days for ZrNiTx and Mg2NiTx. However, LaNi5Tx retains all of the helium generated in the solid for at least 2400 days. NMR measurements for ZrNiTx and Mg2NiTx imply that helium is retained in microscopic bubbles as previously observed in several binary metal tritides.

  14. Brittle intermetallic compound makes ultrastrong low-density steel with large ductility.

    PubMed

    Kim, Sang-Heon; Kim, Hansoo; Kim, Nack J

    2015-02-01

    Although steel has been the workhorse of the automotive industry since the 1920s, the share by weight of steel and iron in an average light vehicle is now gradually decreasing, from 68.1 per cent in 1995 to 60.1 per cent in 2011 (refs 1, 2). This has been driven by the low strength-to-weight ratio (specific strength) of iron and steel, and the desire to improve such mechanical properties with other materials. Recently, high-aluminium low-density steels have been actively studied as a means of increasing the specific strength of an alloy by reducing its density. But with increasing aluminium content a problem is encountered: brittle intermetallic compounds can form in the resulting alloys, leading to poor ductility. Here we show that an FeAl-type brittle but hard intermetallic compound (B2) can be effectively used as a strengthening second phase in high-aluminium low-density steel, while alleviating its harmful effect on ductility by controlling its morphology and dispersion. The specific tensile strength and ductility of the developed steel improve on those of the lightest and strongest metallic materials known, titanium alloys. We found that alloying of nickel catalyses the precipitation of nanometre-sized B2 particles in the face-centred cubic matrix of high-aluminium low-density steel during heat treatment of cold-rolled sheet steel. Our results demonstrate how intermetallic compounds can be harnessed in the alloy design of lightweight steels for structural applications and others. PMID:25652998

  15. Structural and magnetic properties of rare earth—iron–cobalt–vanadium intermetallic compounds (R: Tb, Dy)

    Microsoft Academic Search

    D Hadjiapostolidou; M Gjoka; C Sarafidis; E Pavlidou; T Bakas; O Kalogirou

    2004-01-01

    Starting with the Nd3(Fe,Ti)29 stoichiometry [Tb3(Fe1?xCox)27.4V1.6 and Dy3(Fe1?xCox)27.8V1.2; x=0.6, 0.8, 1.0] two novel series of R–Fe–Co–V intermetallic compounds with a disordered variant of the hexagonal Th2Ni17-type structure were formed. The cell parameters decrease and the Curie temperature increases with increasing Co content. XRD patterns of magnetically aligned powder samples revealed the presence of a planar magnetic anisotropy.

  16. Interaction of hydrogen with the intermetallic compounds Sc 2 Al and Sc 2 Ni

    Microsoft Academic Search

    G. S. Burkhanov; N. B. Kol’chugina; O. D. Chistyakov; V. N. Verbetsky; A. A. Salamova; E. Yu. Andreeva; E. S. Volkova

    2006-01-01

    The reactions of the intermetallic compounds Sc2Al and Sc2Ni with hydrogen have been investigated. The results demonstrate that Sc2Ni reacts with hydrogen even at room temperature, to form amorphous Sc2NiH5. The reaction is irreversible at room temperature. Vacuum extraction of hydrogen between room temperature and 900C leads\\u000a to partial decomposition of Sc2NiH5 and the formation of crystalline ScH2 and ScNi2.

  17. Effect of electromigration on intermetallic compound formation in Cu\\/Sn\\/Cu interconnect

    Microsoft Academic Search

    L. D. Chen; Mingliang Huang

    2009-01-01

    The effect of electromigration on the solid state interfacial reaction of pure Sn and Cu was investigated. Two electron current densities (1.0times104A\\/cm2 and 5.0times103A\\/cm2) were applied to line-type Cu\\/Sn\\/Cu interconnect at 150degC. The same types of intermetallic compound (IMC), Cu6Sn5 and Cu3Sn, formed at the Sn\\/Cu interfaces independent of electric current. A high current density caused a polarity effect where

  18. TDPAC Study of the Intermetallic Compound HfCo 3 B 2

    Microsoft Academic Search

    I. Yaar; I. Halevy; S. Salhov; E. N. Caspi; M. Dubman; S. Kahane; Z. Berant

    2004-01-01

    The electronic properties of the intermetallic compound HfCo3B2 were investigated using combined TDPAC measurements and first principles LAPW calculations. The V\\u000a zz value at the hafnium site is determined from dominant positive p–p contribution, with less than 20%, negative s–d and d–d contributions. Based on the calculated density of state (DOS) at 0 K, a band contribution (?\\u000a band) of 7.26 (mJ\\/mol\\/K2)

  19. Hard surfacing of TiAl intermetallic compound by plasma carburization

    Microsoft Academic Search

    T. Noda; M. Okabe; S. Isobe

    1996-01-01

    For an intermetallic compound such as TiAl to be used in various components, the wear resistance is very important. Recently, plasma carburization was performed on the fully lamellar cast alloy with Ti-33.5Al-1Nb-0.5Cr-0.5Si (mass%). The induced surface layer, 3 ?m in thickness, was a carbide, Ti2AlC, with a hardness that was higher than HV836 for a bearing steel AISI52100. The pin-on-disk

  20. Structural stability and magnetism of metastable Ni-Pt intermetallic compounds studied by ab initio calculation

    Microsoft Academic Search

    XingLai Che; JiaHao Li; Ye Dai; BaiXin Liu

    2009-01-01

    The self-consistent electronic structure calculations were carried out with the accurate frozen-core full-potential projector\\u000a augmented-wave method on 13 Ni-Pt intermetallic compounds of simple crystalline structures, i.e. A15, D019, D03 and L12 Ni3Pt and NiPt3, and ?-NiAs, B1, B2, L2\\u000a a\\u000a , and L10 NiPt. The calculations reveal that the L12 Ni3Pt, L10 NiPt and L12 NiPt3 are energetically more stable

  1. Complex Compound Chemical Heat Pumps

    E-print Network

    Rockenfeller, U.; Langeliers, J.; Horn, G.

    Complex-compound solid-vapor fluid pairs can be used in heat of reaction heat pumps for temperature amplifier (TA) as well as heat amplifier (HA) cycle configurations. This report describes the conceptual hardware design for complex compound...

  2. Structural plasticity: how intermetallics deform themselves in response to chemical pressure, and the complex structures that result.

    PubMed

    Berns, Veronica M; Fredrickson, Daniel C

    2014-10-01

    Interfaces between periodic domains play a crucial role in the properties of metallic materials, as is vividly illustrated by the way in which the familiar malleability of many metals arises from the formation and migration of dislocations. In complex intermetallics, such interfaces can occur as an integral part of the ground-state crystal structure, rather than as defects, resulting in such marvels as the NaCd2 structure (whose giant cubic unit cell contains more than 1000 atoms). However, the sources of the periodic interfaces in intermetallics remain mysterious, unlike the dislocations in simple metals, which can be associated with the exertion of physical stresses. In this Article, we propose and explore the concept of structural plasticity, the hypothesis that interfaces in complex intermetallic structures similarly result from stresses, but ones that are inherent in a defect-free parent structure, rather than being externally applied. Using DFT-chemical pressure analysis, we show how the complex structures of Ca2Ag7 (Yb2Ag7 type), Ca14Cd51 (Gd14Ag51 type), and the 1/1 Tsai-type quasicrystal approximant CaCd6 (YCd6 type) can all be traced to large negative pressures around the Ca atoms of a common progenitor structure, the CaCu5 type with its simple hexagonal 6-atom unit cell. Two structural paths are found by which the compounds provide relief to the Ca atoms' negative pressures: a Ca-rich pathway, where lower coordination numbers are achieved through defects eliminating transition metal (TM) atoms from the structure; and a TM-rich path, along which the addition of spacer Cd atoms provides the Ca coordination environments greater independence from each other as they contract. The common origins of these structures in the presence of stresses within a single parent structure highlights the diverse paths by which intermetallics can cope with competing interactions, and the role that structural plasticity may play in navigating this diversity. PMID:25238606

  3. Characterization of second-phase plates in a Gd5Ge3 intermetallic compound

    SciTech Connect

    Cao, Qing [Ames Laboratory; Chumbley, Leonard S. [Ames Laboratory

    2013-05-16

    Rare-earth compounds based on the stoichiometry R5(SixGe1?x)4 (R = rare-earth elements) exhibit many unusual features, including possessing R5(SixGe1?x)3 thin plates which always precipitate from the matrix despite efforts to suppress their formation. In an effort to better understand the unique relationship between these two intermetallic alloy systems, the bulk microstructure of the compound Gd5Ge3 was examined using scanning (SEM) and transmission electron microscopy (TEM) and optical microscopy. Surprisingly, SEM examination revealed a series of thin plates present in the Gd5Ge3 matrix similar to what is seen in Gd5Ge4. TEM observation revealed that a role reversal had occurred, with the thin plates possessing the orthorhombic structure and composition of Gd5Ge4. The orientation relationship between Gd5Ge4 thin plates and the Gd5Ge3 matrix was determined to be Graphic the same relationship reported for Gd5Ge3 plates precipitating from a Gd5Ge4 matrix. However, by exchanging the respective roles of the phases as regards matrix vs. precipitate, the total number of precipitation variants seen can be increased from two to six. The persistence with which these two intermetallic systems co-exist is truly unique. However, understanding exactly the kinetic and thermodynamic conditions that lead to their unique relationship is hampered by the high formation temperatures at which the observed reaction occurs.

  4. Analysis of valence electron structures (VES) of intermetallic compounds containing calcium in Mg–Al-based alloys

    Microsoft Academic Search

    Xuegang Min; Yangshan Sun; Feng Xue; Wenwen Du; Dengyun Wu

    2003-01-01

    Based on the empirical electron theory (EET), of solid and molecules analysis is made on the Al2Ca, Mg2Ca and Al4Ca intermetallic compounds in Mg–Al alloys containing Ca and the valance electron structures (VES) of these compounds have been calculated. According to the calculative results, bond networks of these compounds have been set up. The analysis and calculation made on these

  5. Study of changes in L32 EELS ionization edges upon formation of Ni-based intermetallic compounds.

    PubMed

    Potapov, P L; Kulkova, S E; Schryvers, D

    2003-04-01

    EELS L32 ionization edges in several Ni-based intermetallic compounds have been studied and interpreted in terms of the distribution of electrons in the valence d-bands. It is demonstrated that the integral EELS cross-sections change only slightly upon the formation of intermetallic compounds and therefore the charge transfer between atoms is negligible. On the other hand, the changes in the fine energy-loss near-edge structure (ELNES) of the Ni L3 edge can be readily detected indicating an important redistribution of d-electrons at the Ni site with alloying. These features are well reproduced by ab-initio calculations with a FLAPW method in its WIEN97 implementation. In contrast to the drastic effect of chemical environment, structural transformations in the investigated intermetallics result in smaller ELNES changes, which can be detected by only exceptional instruments with a higher energy resolution. PMID:12694423

  6. Hyperfine interactions in intermetallic rare earth-gallium compounds studied by 111 Cd PAC

    NASA Astrophysics Data System (ADS)

    Cavalcante, F. H. M.; Pereira, L. F. D.; Saitovitch, H.; Mestnik-Filho, J.; Pasquevich, A. F.; Forker, M.

    2013-05-01

    Magnetic and electric hyperfine interaction of the nuclear probe 111In/111Cd in intermetallic compounds of the rare earth-gallium system have been investigated by perturbed angular correlation (PAC) spectroscopy. The PAC measurements, supported by X-ray diffraction, provide evidence for a marked phase preference of 111In for hexagonal RGa2 over orthorhombic RGa and of RGa3 with the L12 structure over RGa2. In the case of SmGa2, the magnetic hyperfine field Bhf, the electric quadrupole interaction and the angle ? between Bhf and the symmetry axis of the electric field gradient have been determined as a function of temperature. The angle ? = 0 is consistent with the results of previous magnetization studies. Up to T ? 17 K the magnetic hyperfine field has a constant value of Bhf = 3.0(2) T. The rapid decrease at higher T gives the impression of a first-order transition with an order temperature of TN = 19.5 K. In the RKKY model of indirect 4 f interaction the ratio TC/Bhf(0) is a measure of the coupling constant. For 111Cd:SmGa2 (TC/Bhf(0)~6.5 K/T) this ratio is significantly smaller than for the same probe in other R intermetallics (SmAl2 ~9.5 K/T, Sm2In ~13.5 K/T).

  7. Photoemission Study of the Rare Earth Intermetallic Compounds: RNi2Ge2 (R=Eu, Gd)

    SciTech Connect

    Jongik Park

    2004-12-19

    EuNi{sub 2}Ge{sub 2} and GdNi{sub 2}Ge{sub 2} are two members of the RT{sub 2}X{sub 2} (R = rare earth, T = transition metal and X = Si, Ge) family of intermetallic compounds, which has been studied since the early 1980s. These ternary rare-earth intermetallic compounds with the tetragonal ThCr{sub 2}Si{sub 2} structure are known for their wide variety of magnetic properties, Extensive studies of the RT{sub 2}X{sub 2} series can be found in Refs [ 1,2,3]. The magnetic properties of the rare-earth nickel germanides RNi{sub 2}Ge{sub 2} were recently studied in more detail [4]. The purpose of this dissertation is to investigate the electronic structure (both valence band and shallow core levels) of single crystals of EuNi{sub 2}Ge{sub 2} and GdNi{sub 2}Ge{sub 2} and to check the assumptions that the f electrons are non-interacting and, consequently, the rigid-band model for these crystals would work [11], using synchrotron radiation because, to the best of our knowledge, no photoemission measurements on those have been reported. Photoemission spectroscopy has been widely used to study the detailed electronic structure of metals and alloys, and especially angle-resolved photoemission spectroscopy (ARPES) has proven to be a powerful technique for investigating Fermi surfaces (FSs) of single-crystal compounds.

  8. Analysis of the electronic structure of intermetallic compounds, and application to structural defects in B2 phases

    Microsoft Academic Search

    N Börnsen; G Bester; B Meyer; M Fähnle

    2000-01-01

    A general calculational scheme is described to analyse the stability and the defect energetics of intermetallic compounds in terms of a chemical language for the bonding properties. To do this, the contribution to the total energy of bonding and antibonding hybrid states between atom-localized orbitals is determined. This scheme is used to test the general assumption that in the B2

  9. REVIEW ARTICLE: Hydrides formed from intermetallic compounds of two transition metals: a special class of ternary alloys

    Microsoft Academic Search

    K. H. J. Buschow; P. C. P. Bouten; A. R. Miedema

    1982-01-01

    The authors review available experimental information on the existence, thermodynamic stability and physical properties of hydrides formed by the absorption of hydrogen gas in intermetallic compounds of two transition metals. The emphasis is on stability. It is shown that empirical models for the stability of ternary hydrides can be reconciled with ideas based on the results of band structure calculations

  10. Preparation of ?-TiAl intermetallic compounds through self-propagating high-temperature synthesis and compaction

    Microsoft Academic Search

    V. L. Kvanin; N. T. Balikhina; S. G. Vadchenko; I. P. Borovinskaya; A. E. Sychev

    2008-01-01

    Compact materials based on titanium and aluminum are prepared using self-propagating high-temperature synthesis and compaction.\\u000a The parameters of the self-propagating high-temperature synthesis and compaction are optimized for the purpose of producing\\u000a a dense intermetallic compound, namely, ?-TiAl.

  11. Cutting tool performance characteristics in the machining of a nickel aluminide intermetallic compound

    SciTech Connect

    Chatterjee, S. [Univ. of Tennessee, Knoxville, TN (United States); Srivatsan, T.S. [Univ. of Akron, OH (United States); Giusti, P. [Mead Industries, Chillicothe, OH (United States)

    1994-05-01

    Ductile nickel aluminide, Ni{sub 3}Al, containing traces of boron, is an intermetallic compound with high strength, making it a promising structural material for elevated, ambient and cryogenic temperature applications. In order to be able to use alloys, they must be capable of being fabricated by machining. The machinability of a cast nickel aluminide, Ni{sub 3}Al, alloy containing boron was studied by conventional machining using the lathe. Three different cutting tool inserts and two types of coolants, namely kerosene oil mist and soluble oil, were chosen. The machining performance of the cutting tool insert and the influence of coolant type were established through measurements of volume of material removed and tool wear. The tool wear analysis was made using microscopic examination of the cutting tool insert in order to elucidate information of the influence of machining parameters and choice of coolant on performance capability of the insert. The overall machinability performance of these materials is rationalized.

  12. Magnetostriction and magnetism of rare earth intermetallic compounds: First principle study

    SciTech Connect

    Gavrilenko, V. I.; Wu, R. Q.

    2001-06-01

    Magnetism and magnetostriction of rare earth intermetallic compounds, GdCo{sub 2}, GdFe{sub 2}, NdCo{sub 2}, SmCo{sub 2}, and ErCo{sub 2}, have been studied by using the first principles full-potential linearized augmented plane-wave method with the generalized gradient approximation. The calculated magnetostriction coefficients agree well with experiment. The itinerant electrons of transition metal elements are found to play a significant role in magnetoelastic coupling. The strong anisotropy of magnetostriction in GdCo{sub 2} is explained. Contributions due to spatial anisotropic charge distribution of the incomplete 4f shells are calculated and discussed. {copyright} 2001 American Institute of Physics.

  13. SHS combustion characteristics of several ceramics and intermetallic compounds. [Self-propagating High-temperature Synthesis

    SciTech Connect

    Makino, Atsushi (Shizuoka Univ., Hamamatsu (Japan). Dept. of Energy and Mechanical Engineering); Law, C.K. (Princeton Univ., NJ (United States). Dept. of Mechanical and Aerospace Engineering)

    1994-03-01

    Extensive comparisons have been conducted between experimental and theoretical results for the SHS combustion characteristics of a number of solid-solid systems. The heterogeneous flame propagation theory describes a premixed mode of bulk flame propagation supported by the nonpremixed reaction of dispersed nonmetal (or higher melting point metal) particles in the liquid metal, with finite-rate reaction at the particle surface and temperature-sensitive Arrhenius-type condensed-phase mass diffusivity. Systems examined are those of borides (TiB[sub 2], ZrB[sub 2], and HfB[sub 2]) and intermetallic compounds (NiAl, TiCo, and TiNi). By using a consistent set of physico-chemical parameters for these systems, satisfactorily quantitative agreement is demonstrated for the effects of mixture ratio, degree of dilution, and particle size on the burning velocity. Experimental flammability limits are also predicted by the theory.

  14. Gas atomization synthesis of refractory or intermetallic compounds and supersaturated solid solutions

    DOEpatents

    Anderson, Iver E. (Ames, IA); Lograsso, Barbara K. (Ames, IA); Ellis, Timothy W. (Ames, IA)

    1994-01-01

    A metallic melt is atomized using a high pressure atomizing gas wherein the temperature of the melt and the composition of the atomizing gas are selected such that the gas and melt react in the atomization spray zone to form a refractory or intermetallic compound in the as-atomized powder particles. A metallic melt is also atomized using a high pressure atomizing gas mixture gas wherein the temperature of the melt and the ratio of a reactive gas to a carrier gas are selected to form powder particles comprising a supersaturated solid solution of the atomic species of the reactive gas in the particles. The powder particles are then heat treated to precipitate dispersoids in-situ therein to form a dispersion strengthened material.

  15. Gas atomization synthesis of refractory or intermetallic compounds and supersaturated solid solutions

    DOEpatents

    Anderson, I.E.; Lograsso, B.K.; Ellis, T.W.

    1994-11-29

    A metallic melt is atomized using a high pressure atomizing gas wherein the temperature of the melt and the composition of the atomizing gas are selected such that the gas and melt react in the atomization spray zone to form a refractory or intermetallic compound in the as-atomized powder particles. A metallic melt is also atomized using a high pressure atomizing gas mixture gas wherein the temperature of the melt and the ratio of a reactive gas to a carrier gas are selected to form powder particles comprising a supersaturated solid solution of the atomic species of the reactive gas in the particles. The powder particles are then heat treated to precipitate dispersoids in-situ therein to form a dispersion strengthened material. 9 figures.

  16. Synthesis and characterization of patterned surfaces and catalytically relevant binary nanocrystalline intermetallic compounds

    E-print Network

    Cable, Robert E.

    2008-10-10

    ........................................ 39 2.17 TEM images of AuPd 4 made by the nanocomposite route and supported on porous SiO 2 catalyst support ....................................... 40 3.1 Powder XRD patterns for nanocrystalline intermetallics (a) M-Sn [Ag 4 Sn, Au 5 Sn, Fe... binary intermetallic powders .......... 50 3.4 Study of phase formation in the Fe-Sn system ............................. 56 3.5 Morphology of nanocrystalline intermetallics.............................. 63 vii CHAPTER Page III 3...

  17. Growth of a Au-Ni-Sn intermetallic compound on the solder-substrate interface after aging

    SciTech Connect

    Minor, Andrew M.; Morris, J.W., Jr.

    1999-12-16

    Au/Ni metallization has become increasingly common in microelectronic packaging when Cu pads are joined with Pb-Sn solder. The outermost Au layer serves to protect the pad from corrosion and oxidation and the Ni layer provides a diffusion barrier to inhibit detrimental growth of Cu-Sn intermetallics. As a result of reflowing eutectic Pb-Sn on top of Au/Ni metallization, the as-solidified joints have AuSn{sub 4} precipitates distributed throughout the bulk of the solder joint, and Ni{sub 3}Sn{sub 4} intermetallics at the interface. Recent work has shown that the Au-Sn redeposits onto the interface during aging, compromising the strength of the joint. The present work shows that the redeposited intermetallic layer is a ternary compound with stoichiometry Au{sub 0.5}Ni{sub 0.5}Sn{sub 4}. The growth of this intermetallic layer was investigated, and results show that the ternary compound is observed to grow after as little as 3 hours at 150 C and after 3 weeks at 150 C has grown to a thickness of 10 {micro}m. Additionally, methods for inhibiting the growth of the ternary layer were investigated and it was determined that multiple reflows, both with and without additional aging can substantially limit the thickness of the ternary layer.

  18. Physical properties and magnetic structure of the intermetallic CeCuBi2 compound

    NASA Astrophysics Data System (ADS)

    Adriano, C.; Rosa, P. F. S.; Jesus, C. B. R.; Mardegan, J. R. L.; Garitezi, T. M.; Grant, T.; Fisk, Z.; Garcia, D. J.; Reyes, A. P.; Kuhns, P. L.; Urbano, R. R.; Giles, C.; Pagliuso, P. G.

    2014-12-01

    In this work we combine magnetization, pressure dependent electrical resistivity, heat capacity, 63Cu nuclear magnetic resonance (NMR), and x-ray resonant magnetic scattering experiments to investigate the physical properties of the intermetallic CeCuBi2 compound. Our single crystals show an antiferromagnetic ordering at TN?16 K and the magnetic properties indicate that this compound is an Ising antiferromagnet. In particular, the low temperature magnetization data revealed a spin-flop transition at T =5 K when magnetic fields of about 5.5 T are applied along the c axis. Moreover, the x-ray magnetic diffraction data below TN revealed a commensurate antiferromagnetic structure with propagation wave vector (00 1/2 ) with the Ce3 + moments oriented along the c axis. Furthermore, our heat capacity, pressure dependent resistivity, and temperature dependent 63Cu NMR data suggest that CeCuBi2 exhibits a weak heavy fermion behavior with strongly localized Ce3 + 4 f electrons. We thus discuss a scenario in which both the anisotropic magnetic interactions between the Ce3 + ions and the tetragonal crystalline electric field effects are taking into account in CeCuBi2.

  19. Magnetic field controlled floating-zone single crystal growth of intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Hermann, R.; Gerbeth, G.; Priede, J.

    2013-03-01

    Radio-frequency (RF) floating zone single crystal growth is an important technique for the preparation of single bulk crystals. The advantage of the floating-zone method is the crucible-free growth of single crystals of reactive materials with high melting points. The strong heat diffusion on the surface, as well as the melt convection in the molten zone due to induction heating, often leads to an undesired solid-liquid interface geometry with a concave (towards the solid phase) outer rim. These concave parts aggravate the single crystal growth over the full cross-section. A two-phase stirrer was developed at IFW Dresden in order to avoid the problems connected with these concave parts. It acts as a magnetic field pump and changes the typical double vortex structure to a single roll structure, thus pushing hot melt into the regions where the concave parts may arise. The current in the secondary coil is induced by the primary coil, and the capacitor and the resistance of the secondary circuit are adjusted to get a stable 90 degree phase-shift between the coil currents. Single crystal growth of industrial relevant RuAl and TiAl intermetallic compounds was performed based on the material parameters and using the adjusted two-phase stirrer. Very recently, the magnetic system was applied to the crystal growth of biocompatible TiNb alloys and antiferromagnetic Heusler MnSi compounds.

  20. Structural intermetallics

    Microsoft Academic Search

    R. Darolia; J. J. Lewandowski; C. T. Liu; P. L. Martin; D. B. Miracle; M. V. Nathal

    1993-01-01

    The intent of the symposium was to provide a detailed and in-depth perspective of the approaches, results and progress toward the structural application of intermetallic compounds and their composites. Longer and insightful presentations which focused on real progress and trends rather than recent results, and extended discussion periods formed the centerpiece of this symposium to achieve these goals. Emphasis was

  1. Effect of randomness of Cu-Sn intermetallic compound layer thickness on reliability of surface mount solder joints

    Microsoft Academic Search

    Wei Huang; Olgierd A. Palusinski; Duane L. Dietrich

    2000-01-01

    A statistical reliability analysis on thermal fatigue lifetime of surface mount solder joints, considering randomness of Cu-Sn intermetallic compound (IMC) layer thickness, is presented. Based on published thermal fatigue life test data, the two-parameter Weibull distribution of the thermal fatigue lifetime for a fixed IMC layer thickness is found, and a K-S goodness-of-fit test is conducted to examine the goodness

  2. The formation and growth of intermetallic compounds and shear strength at Sn-Zn solder\\/Au-Ni-Cu interfaces

    Microsoft Academic Search

    K. S. Kim; K. W. Ryu; C. H. Yu; J. M. Kim

    2005-01-01

    The microstructures and shear strength of the interface between Sn–Zn lead-free solders and Au\\/Ni\\/Cu interface under thermal aging conditions was investigated. The intermetallic compounds (IMCs) at the interface between Sn–Zn solders and Au\\/Ni\\/Cu interface were analyzed by field emission scanning electron microscopy and transmission electron microscopy. The results showed the decrease in the shear strength of the interface with aging

  3. Investigation of InBi intermetallic compounds as possible topological insulators

    NASA Astrophysics Data System (ADS)

    Lin, Y. T.; Chen, Q. Y.; Hseih, W. C.; Chang, C. F.; Chuang, F. C.; Liao, H. H.

    2015-03-01

    InBi intermetallic compounds were found to be potentially 2-dimensional topological insulators from first-principle calculations. In our experiment, InBi, In2Bi3andIn3Bi5 were fabricated either in bulk or thin film, by depositing In and Bi into 2 layers by e-beam evaporation of proper thickness ratios for each stoichiometry. The bi-layers were rapid thermal annealed to accomplish the reaction or intermixing well above their temperatures of phase transition. EDS and secondary electron imaging were used to determine the obtained stoichiometry. CVD using a 3-zone furnace was as tested with various combinations of zone temperatures, types and flow rates of carrying gases to investigate the feasibility of epitaxial growth. Samples were characterized by XRD to obtain the crystalline phase, magneto-transport measurements to determine the carrier concentration and mobility using a PPMS to correlate the measured results. We will ponder on the implication of our findings in regards to the possibilities of being a candidate for topological insulator as predicted by the calculations.

  4. Effect of Loading Stress on the Growth of Cn/Sn Intermetallic Compounds at High Temperatures

    NASA Astrophysics Data System (ADS)

    Cheng, Ya-Chi; Wang, Yu-Ting; Hsu, Feng-Chih; Lu, Fang-Ching; Wu, Chung-Lin; Lin, Ming-Tzer

    2015-01-01

    Fabrication of reliable solder joints is crucial in microelectronics. In this study we tested solder joints under different loads and temperature-controlled conditions to investigate the effect of external stress on the growth of interfacial Cu/Sn intermetallic compounds (IMCs). Test specimens were prepared by electroplating a layer of Sn (25 ?m thick) on a copper substrate. Samples were then clamped in a micromechanical testing apparatus integrated within a furnace. Experiments were performed by using load feedback control to ensure a constant load of 25, 50, or 100 MPa at a constant temperature of 200°C for periods of 24, 72, or 120 h. We then compared samples that underwent stress with those that did not to elucidate the effect of stress and aging on the formation of IMCs. Our results indicate that the presence of external stress affects the formation of Cu/Sn IMCs, including the speed of formation and the resulting thickness. Moreover, the micrographic structure of IMCs formed under external stress varied substantially depending on the amount of stress applied.

  5. Growth kinetics of Al–Fe intermetallic compounds during annealing treatment of friction stir lap welds

    SciTech Connect

    Movahedi, M., E-mail: m_movahedi@sharif.edu [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Azadi Ave., Tehran (Iran, Islamic Republic of); Kokabi, A.H., E-mail: kokabi@sharif.edu [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Azadi Ave., Tehran (Iran, Islamic Republic of); Seyed Reihani, S.M., E-mail: reihani@sharif.edu [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Azadi Ave., Tehran (Iran, Islamic Republic of); Najafi, H., E-mail: hossein.najafi@epfl.ch [Institute of Condensed Matter Physics (ICMP), EPFL, CH-1015 Lausanne (Switzerland); Farzadfar, S.A., E-mail: seyed-amir.farzadfar@mail.mcgill.ca [McGill University, Department of Materials Engineering, Montreal, QC H3A 2B2 (Canada); Cheng, W.J., E-mail: d9603505@mail.ntust.edu.tw [Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan, ROC (China); Wang, C.J., E-mail: cjwang@mail.ntust.edu.tw [Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan, ROC (China)

    2014-04-01

    In this study, we explored the growth kinetics of the Al–Fe intermetallic (IM) layer at the joint interface of the St-12/Al-5083 friction stir lap welds during post-weld annealing treatment at 350, 400 and 450 °C for 30 to 180 min. Optical microscope (OM), field emission gun scanning electron microscope (FEG-SEM) and transmission electron microscope (TEM) were employed to investigate the structure of the weld zone. The thickness and composition of the IM layers were evaluated using image analysis system and electron back-scatter diffraction (EBSD), respectively. Moreover, kernel average misorientation (KAM) analysis was performed to evaluate the level of stored energy in the as-welded state. The results showed that the growth kinetics of the IM layer was not governed by a parabolic diffusion law. Presence of the IM compounds as well as high stored energy near the joint interface of the as-welded sample was recognized to be the origin of the observed deviation from the parabolic diffusion law. - Highlights: • This work provided a new insight into growth kinetics of Al–Fe IM thickness. • The growth kinetics of IM layer was not governed by a parabolic diffusion law. • IM near the joint interface was the origin of deviation from the parabolic law. • High stored energy at joint interface was origin of deviation from parabolic law.

  6. Thermodynamics of Pu-Pt and Pu-Rh intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Peterson, Dean E.

    1985-03-01

    The sublimation behavior and thermodynamic properties for several Pu-Pt and Pu-Rh compounds were determined in this study. Vapor pressures were measured by the Knudsen effusion technique using target collection and mass spectrometry. Sublimation to form elemental Pu(g) predominates for the phases and temperature ranges selected. The mean temperature (K), enthalpy (kJ/mol) and entropy (J/K · mol)) of sublimation determined by second law least squares analysis for each compound are as follows: PuPt 5 (1614, 626.3±27.1, 177.0±16.6); PuPt 4 (1596, 492.0±30.5, 102.3±18.8); PuPt 3, (1579, 495.8±12.6, 119.2±7.9); PuPt 2 (1629, 467.3±18.0, 107.4±10.9); PuRh 3 (1725, 577.8±15.1, 166.5±8.9); and PuRh 2 (1519, 499.6±33.0, 121.2±21.7). Third-law analyses using estimated free energy functions yielded the following enthalpies (kJ/mol) of sublimation and formation respectively at 298 K: PuPt 5 ( 610.0±7.5, -264.8±8.0); PuPt 4 ( 510.0±8.5, -244.8±9.0); PuPt 3 ( 487.0±6.0, -219.0±6.5); PuPt 2 ( 477.0±5.5, -189.9±7.5), PuRh 3 ( 543.1±6.5, -197.9±7.5) and PuRh 2 ( 487.8±8.7, -179.5±9.2). Thermodynamic properties determined in this study are correlated with values obtained from theoretical predictions and from previous studies on analogous intermetallics.

  7. Interaction of Oxygen and Carbon Monoxide with Cerium and Lanthanum Intermetallic Compounds

    NASA Astrophysics Data System (ADS)

    Wu, Ming

    In intermetallic compounds of Ce, the hybridization of the Ce 4f states and the conduction electron states generally results in an increase of the density of states at the Fermi level and has a profound effect on the transport, thermal, magnetic, and other physical properties of these compounds. In an attempt to determine whether these modifications are reflected in the catalytic properties, Auger electron spectroscopy (AES) and temperature programmed desorption (TPD) have been employed for an investigation of the interaction of O_2 and CO with CeIr _2 and its isostructural counterpart LaIr _2. Results from CeIr_2 and LaIr_2 show the following differences: (1) oxygen and carbon penetrate into CeIr _2<=ss deeply than LaIr _2; (2) O_2 and CO exhibit high temperature peaks (at 610 K for O _2 and at 740 and 900 K for CO) in the TPD spectra from the CeIr_2 sample not present in those from the LaIr_2 sample; (3) when the compounds are predosed with CO, substantial thermal desorption of CO_2 occurs from LaIr_2, but none from CeIr _2. Considering that La and Ce are chemically almost identical and the CeIr_2 and LaIr_2 bulk compounds are isostructural, the above differences suggest that the intermediate valence of CeIr_2 affects the interaction with gases. However, no direct relation has been established between the large density of states at the Fermi level and the differences in the interactions, due to the complications related to the presence of CeO _2. Unusual properties discussed are the formation of surface and near-surface oxide species upon exposure to O_2 or CO, the dissociative adsorption of CO and recombination of CO, the production of CO _2, thermal segregation, and subsurface "reservoir" of C and O. Surface and subsurface processes, such as adsorption and penetration, or thermal segregation, recombination, and desorption, are strongly coupled together. A consistent interpretation of the AES data requires consideration of the C and O concentrations occurring in the surface-subsurface region. A procedure for the conversion of AES data into concentrations is developed employing piecewise fitting with exponential decay functions. When LaIr_2 is dosed with CO, oxidation occurs, but TPD studies reveal that the sample remains chemically active, desorbing the equivalent of more than a monolayer of CO and CO_2. This suggests the presence of a certain kinetic mechanism that allows the preservation of the catalytic activity under oxidation, implying the potential for poison-resistance application.

  8. An electronic criterion for the intrinsic embrittlement of structural intermetallic compounds

    SciTech Connect

    Li, W.; Wang, Y.; Cai, M.; Wang, C.W. [Department of Mechanical Engineering, Changchun University, Changchun, 130022 (China); School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, 150006 (China); School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, 150006 (China); Department of Physics, P.O. Box 642814, Washington State University, Pullman, Washington 99164-2814 (United States); Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Wuhan Institute of Technology, Wuhan, 470074 (China)

    2005-10-15

    Development of intermetallics for high-temperature structural applications has long been impeded by their brittleness. To overcome the brittleness, efforts have been devoted to understand the atomic bonding nature of intermetallics. However, there are no simple theoretical or experimental means for investigating the electronic origin of the brittleness. We find a simple experimental method, which employs the Kelvin-probe technique to measure the electron work function. The typical intermetallics in three alloy systems (Ni-Al, Fe-Al, and Ti-Al) were chosen as examples. An electronic criterion was therefore proposed for judging intrinsic brittleness. This criterion could provide some principles for improving the ductility of intermetallics and is also expected to be extendable to other materials (e.g., quasicrystalline alloys and metallic glasses)

  9. Icosahedron oligomerization and condensation in intermetallic compounds. Bonding and electronic requirements.

    PubMed

    Tillard-Charbonnel, M; Manteghetti, A; Belin, C

    2000-04-17

    Icosahedron-based clustering has been found to be very common in intermetallics, particularly for group 13 and early p-block icosogen elements. Linking of the icosahedral building blocks depends on the valence electron concentrations. Vertex-, edge-, or face-sharing icosahedra occur as the structure compensates for electron deficiency. Some examples of icosahedron-based clusters have been selected for an analysis of the relationships between the structural features (icosahedron oligomerization, atomic defects, etc.) and the bonding and electronic requirements. The extended Hückel method has been used with either a molecular approach or an electronic band structure calculation to rationalize bonding in the intermetallic framework. PMID:12526555

  10. Structural intermetallics

    SciTech Connect

    Darolia, R.; Lewandowski, J.J.; Liu, C.T.; Martin, P.L.; Miracle, D.B.; Nathal, M.V. (eds.)

    1993-01-01

    The intent of the symposium was to provide a detailed and in-depth perspective of the approaches, results and progress toward the structural application of intermetallic compounds and their composites. Longer and insightful presentations which focused on real progress and trends rather than recent results, and extended discussion periods formed the centerpiece of this symposium to achieve these goals. Emphasis was placed on a balance of presentations covering basic research, alloy development and applications. Programs of large magnitudes are being carried out throughout the world to develop intermetallics for structural applications. Programs of large magnitudes are being carried out throughout the world to develop intermetallics for structural applications. The majority of the focus is on the development of microstructure and alloy compositions to solve the poor ductility and toughness of these intermetallics. Considerable progress has been made in understanding as well as solving the ductility and toughness issues. Component and engine tests are being initiated with Ti[sub 3]Al, TiAl, Ni[sub 3]Al and NiAl alloys. Separate abstracts were prepared for 94 papers in this symposium.

  11. Solid state intermetallic compound growth between copper and high temperature, tin-rich solders—part I: Experimental analysis

    Microsoft Academic Search

    P. T. Vianco; K. L. Erickson; P. L. Hopkins

    1994-01-01

    An experimental study was performed which examined the solid state growth kinetics of the interfacial intermetallic compound\\u000a layers formed between copper and the high temperature, tin-rich solders 96.5Sn-3.5Ag (wt.%) and 95Sn-5Sb. These results were\\u000a compared with baseline data from the 100Sn\\/copper system. Both the 96.5Sn-3.5Ag and 95Sn-5Sb solders exhibited the individual\\u000a Cu3Sn and Cu6Sn5 layers at the interface; the thickness

  12. Hydrogen Sorption and Electrochemical Properties of Intermetallic Compounds La 2 Ni 7 and La 2 Ni 6 Co

    Microsoft Academic Search

    E. Levin; P. Donskoy; S. Lushnikov; V. Verbetsky; T. Safonova; O. Petrii

    Intermetallic compounds (IMCs) La2Ni7and La2Ni6Co were obtained by arc melting technique followed by annealing. Samples were characterized by means of X-ray powder diffraction (XRD). Crystal structure of ?-La2Ni7was refined using single crystal X-ray data. Hydrogen desorption isotherms were obtained for La2Ni7and La2Ni6Co at T=273K and T=295K. Electrochemical discharge properties of La2Ni7and La2Ni6Co were investigated. The introduction of Co in alloy

  13. Electronic and high pressure elastic properties of RECd and REHg (RE=Sc, La and Yb) intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Devi, Hansa; Pagare, Gitanjali; Chouhan, Sunil S.; Sanyal, Sankar P.

    2015-01-01

    Structural, electronic, elastic and mechanical properties of Cd and Hg based rare earth intermetallics (RECd and REHg; RE=Sc, La and Yb) have been investigated using the full-potential linearized augmented plane-wave (FP-LAPW) method within the density-functional theory (DFT). The ground state properties such as lattice constant (a0), bulk modulus (B) and its pressure derivative (B?) have been obtained using optimization method and are found in good agreement with the available experimental results. The calculated enthalpy of formation shows that LaHg has the strongest alloying ability and structural stability. The electronic band structures and density of states reveal the metallic character of these compounds. The structural stability mechanism is also explained through the electronic structures of these compounds. The chemical bonding between rare earth atoms and Cd, Hg is interpreted by the charge density plots along (1 1 0) direction. The elastic constants are predicted from which all the related mechanical properties like Poisson's ratio (?), Young's modulus (E), shear modulus (GH) and anisotropy factor (A) are calculated. The ductility/brittleness of these intermetallics is predicted. Chen's method has been used to predict the Vicker's hardness of RECd and REHg compounds. The pressure variation of the elastic constants is also reported in their B2 phase.

  14. The Effect of Gold-Tin Intermetallic Compound on the Low Cycle Fatigue Behavior of Copper Alloy C72700 and C17200 Wires

    Microsoft Academic Search

    A. Fox; MERLE E. DAVIS; PHILIP R. WHITE; THOMAS A. PALUMBO; CHARLES A. MATTOE

    1986-01-01

    Many connectors and springs fabricated from copper base spring materials require a gold-plated surface finish. Often such parts are joined or interconnected to the electronic package by soldering with tinlead solder. Upon application of heat, the gold plating may interact with the tin contained in the solder to produce a brittle intermetallic compound. Such a compound may adversely affect the

  15. Structural and physical properties of the new intermetallic compound Yb{sub 3}Pd{sub 2}Sn{sub 2}

    SciTech Connect

    Solokha, P. [Dipartimento di Chimica e Chimica Industriale, Universita di Genova, Via Dodecaneso 31, 16146 Genova (Italy); Curlik, I. [Institute of Experimental Physics, Watsonova 47, SK 043 53 Kosice (Slovakia); Giovannini, M., E-mail: giovam@chimica.unige.it [Dipartimento di Chimica e Chimica Industriale, Universita di Genova, Via Dodecaneso 31, 16146 Genova (Italy); Lee-Hone, N.R. [Physics Department and Centre for the Physics of Materials, McGill University, Montreal, Canada H3A 2T8 (Canada); Reiffers, M. [Institute of Experimental Physics, Watsonova 47, SK 043 53 Kosice (Slovakia); Faculty of Sciences, University of Presov, 17. Novembra 1, SK 080 78 Presov (Slovakia); Ryan, D.H. [Physics Department and Centre for the Physics of Materials, McGill University, Montreal, H3A 2T8 (Canada); Saccone, A. [Dipartimento di Chimica e Chimica Industriale, Universita di Genova, Via Dodecaneso 31, 16146 Genova (Italy)

    2011-09-15

    The crystal structure of the ternary intermetallic compound Yb{sub 3}Pd{sub 2}Sn{sub 2} has been determined ab initio from powder X-ray diffraction data. The compound crystallizes as a new structure type in the orthorhombic space group Pbcm and lattice constants a=0.58262(3), b=1.68393(8), c=1.38735(7) nm. Yb{sub 3}Pd{sub 2}Sn{sub 2} is composed of a complex {sub {infinity}}[Pd{sub 2}Sn{sub 2}]{sup {delta}-} polyanionic network in which the Yb ions are embedded. A comparison between this structure and those of Eu{sub 3}Pd{sub 2}Sn{sub 2} and Ca{sub 3}Pd{sub 2}Sn{sub 2}, other novel polar intermetallic compounds, was made. DC susceptibility and {sup 170}Yb Moessbauer spectroscopic measurements indicate a close-to divalent Yb behavior. Moreover, a hybridization between 4f and conduction electrons is suggested by electronic structure calculations and heat capacity measurements. - Graphical Abstract: Polyanionic networks for Yb{sub 3}Pd{sub 2}Sn{sub 2} and Eu{sub 3}Pd{sub 2}Sn{sub 2}. Highlights: > We determined ab initio the crystal structure of the novel ternary Yb{sub 3}Pd{sub 2}Sn{sub 2} stannide. > This structure has been compared with those of other polar 3:2:2 stannides discovered in this work. > Measurements of physical properties on Yb{sub 3}Pd{sub 2}Sn{sub 2} point to a close-to-divalent Yb ion. > Electron structure calculation and heat capacity indicate some hybridization between 4f and conduction electrons.

  16. Growth behavior of intermetallic compounds during reactive diffusion between aluminum alloy 1060 and magnesium at 573-673 K

    NASA Astrophysics Data System (ADS)

    Xiao, Lin; Wang, Ning

    2015-01-01

    A potential new research reactor fuel design proposes to use U-Mo fuel in a Mg matrix clad with Al. Interdiffusion between the Mg containing fuel core and Al cladding can result in the formation of intermetallic compounds that can be detrimental to fuel element performance. The kinetics of the reactive diffusion in the binary Al-Mg system was experimentally studied. Layers of the intermetallic compounds, ? (Al3Mg2) and ? (Al12Mg17) phases, were formed between the Al alloy 1060 and Mg during annealing. The ? layer was observed to grow faster than the ? phase. The thickness of each layer can be expressed by a power function of the annealing time with the exponent n close to 0.5 for the ? phase and less than 0.5 for the ? phase. The results suggest that the growth of ? phase is controlled by lattice diffusion and that of the ? phase by grain boundary and lattice diffusion. Metallographic examination showed the grain boundary diffusion in the form of columnar growth of ? phase during annealing. Based on the reactive diffusion equation developed in this work, in the absence of irradiation effects, it will take more than 110 h to consume a half thickness of 400 ?m of the cladding.

  17. Native metals and intermetallic compounds in heavy concentrate halos of the Ol'khovaya-1 River, Kamchatsky Mys Peninsula, eastern Kamchatka

    NASA Astrophysics Data System (ADS)

    Sandimirova, E. I.; Sidorov, E. G.; Chubarov, V. M.; Ibragimova, E. K.; Antonov, A. V.

    2014-12-01

    Various native metals (Pb, Sn, Bi, and Cu) and intermetallic compounds (Au-Pb), (Au-Ag-Pb-Sb), (Pb-Sb), (Pb-Sn), and (Au-Ag-Pb-Sn) have been revealed in placer gold deposits in the Ol'khovaya-1 River and heavy concentrate halos on the Kamchatsky Mys Peninsula, eastern Kamchatka. Interrelations (intergrowths and inclusions) of these metals and intermetallic compounds with gold and host rocks show that they are of natural origin and genetically related to the hydrothermal metasomatic alteration of the Kamchatsky Mys ultramafic massif.

  18. Crystal Structure of the Intermetallic Compound Mg3Cr2Al18

    Microsoft Academic Search

    Sten Samson

    1954-01-01

    A TERNARY intermetallic phase with the approximate composition MgCrAl8, called the E-phase, was observed by Erdmann-Jesnitzer1 in his examination of the magnesium-chromium-aluminium system. Little, Axon and Hume-Rothery2 found that the magnesium content of the E-phase can vary considerably, and that, furthermore, zinc is soluble in the phase to some extent. Crystals extracted from two ternary alloys were found on analysis

  19. Radiation effects in FCC metals and intermetallic compounds: A molecular dynamics computer simulation study

    SciTech Connect

    Diaz de la Rubia, T.; Guinan, M.W. [Lawrence Livermore National Lab., CA (United States); Caro, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1992-11-16

    We review recent results on atomic mixing, radiation-induced disordering, and defect production and clustering induced by displacement cascades in Cu, Ag, Cu{sub 3}Au and Ni{sub 3}Al. We employ molecular dynamics computer simulation methods with isotropic many body potentials and recoil energies near subcascade formation regime up the locally molten cascade core in the pure metals and intermetallics. Disordering of intermetallics takes place in the cascade core, but because of the short lifetime of the displacement cascade, chemical short range order is preserved in molten zone. Results reveal very large vacancy and interstitial type defect clusters at high recoil energy and cascade energy density. Vacancies agglomerate and collapse into Frank dislocation loops in quenching of the cascade molten core. Large interstitial clusters are directly produced in cascades and form prismatic dislocation loops. Fraction of defects in clusters for low temperature cascades increases with recoil energy and approaches {approx} 70 and 60% for interstitials and vacancies, at recoil energies near threshold for subcascades. In the case of intermetallics the large energy required to produce and transport a superdislocation appears to inhibit interstitial prismatic loop punching and interstitials appear as isolated (100) dumbbells.

  20. Nanocluster model of intermetallic compounds with giant unit cells: beta, beta'-Mg(2)Al(3) polymorphs.

    PubMed

    Blatov, Vladislav A; Ilyushin, Gregory D; Proserpio, Davide M

    2010-02-15

    A novel method for the computational description of intermetallics as an assembly of nanoclusters was improved and applied to extremely complicated crystal structures of beta, beta'-Mg(2)Al(3) polymorphs. Using the TOPOS program package that implements the method, we separated two types of two-shell primary nanoclusters A, A1, A2, and B consisting of 57-63 atoms that completely compose the structures of the polymorphs. The nanocluster model interprets structural disordering in beta-Mg(2)Al(3): the disordered atoms form the inner shell of the nanocluster A, while the outer shells of all nanoclusters are preserved. The self-assembly of the beta, beta'-Mg(2)Al(3) crystal structures was considered within the hierarchical scheme: 0D primary polyhedral clusters (coordination polyhedra) --> 0D two-shell primary nanoclusters A, A1, A2, or B --> 0D supracluster-precursor AB(2) --> 1D primary chain --> 2D microlayer --> 3D microframework. The self-assembly scheme proves the similarity of beta, beta'-Mg(2)Al(3) to other extremely complicated Samson's phases, NaCd(2) and ZrZn(22); the spatial arrangement of the centers of nanoclusters in these structures as well as the topology of the corresponding network conform to the Laves phase MgCu(2). Using the TOPOS procedure of searching for finite fragments in infinite nets we found that nanocluster B is a typical fragment of intermetallic compounds: it exists in intermetallics belonging to 42 Pearson classes. The nanocluster A was found only in two Pearson classes: cF464 and hP238, while the nanoclusters A1 and A2 occur in beta'-Mg(2)Al(3) only. Thus, the nanoclusters A, A1, and A2 can be considered as "determinants" of the corresponding structures. PMID:20063861

  1. Surface composition of ordered intermetallic compounds PtBi and PtPb

    NASA Astrophysics Data System (ADS)

    Blasini, D. R.; Rochefort, D.; Fachini, E.; Alden, L. R.; DiSalvo, F. J.; Cabrera, C. R.; Abruña, H. D.

    2006-07-01

    The surface composition of bulk electrodes made from the ordered intermetallic phases PtBi and PtPb has been studied by ex-situ X-ray photoelectron spectroscopy (XPS) after being subjected to various electrochemical treatments. Analysis of the freshly polished surfaces showed that in the surface and near surface regions the less-noble metals; Bi and Pb are oxidized to a significant extent (28% and 41%, respectively). Upon cycling to increasingly positive potentials, the fraction of oxidized to metallic forms of Bi and Pb decreased gradually to reach the minimal values of 7% and 6% at +400 mV vs. Ag/AgCl (saturated KCl). The observed decrements are due to leaching of surface oxides; Bi 2O 3 on PtBi and PbCO 3 or Pb(OH) 2 on PtPb. When the potential sweep was extended to more positive values, there was a linear decrease in the surface concentration of the less-noble metal, along with a slight increase in the amount of the species in their oxidized state (Bi 2O 3 for PtBi and PbSO 4 for PtPb). Leaching of Bi from the electrode surface occurs in accordance to the Pourbaix diagram for elemental bismuth, indicating no significant increase in stability arising from the formation of an intermetallic phase with platinum. In the case of PtPb, however, the Pb starts to dissolve away at potentials significantly more positive (+800 mV) than what was anticipated from the Pourbaix diagram. The results obtained here are in accord with our previous observations on the effects of electrochemical pre-treatment on these intermetallic phases for the electrocatalytic oxidation of formic acid and other potential fuel cell fuels.

  2. Synthesis and characterization of patterned surfaces and catalytically relevant binary nanocrystalline intermetallic compounds 

    E-print Network

    Cable, Robert E.

    2009-05-15

    representing the angles of reflections for ?-Sn (bottom) and FeSn 2 (top). For each different reaction the XRD patterns corresponds to the product isolated from 0.5 hr (bottom patterns) to 2 hr (top patterns) in 0.5 hr intervals... not originally discovered using traditional bulk syntheses. 43 In Chapter III, we show that the polyol process is quite general for the synthesis of intermetallic nanocrystals, specifically in the systems M-Sn (M = Ag, Au, Co, Cu, Fe, Ni), Pt-M? (M? = Bi, Pb...

  3. JOURNAL DE PHYSIQUE Colloque C4, supplment au n" 4, Tome 40, avril 1979, page C4-142 Magnetic neutron scattering on intermetallic uranium compounds (*)

    E-print Network

    Paris-Sud XI, Université de

    neutron scattering on intermetallic uranium compounds (*) M. Loewenhaupt (f ), S. Horn (**), F. Steglich.- Abstract. -- We report on inelastic neutron scattering experiments performed in the temperature range 5 K quasielastic line. Using thermal neutrons, no inelastic contributions to the magnetic scattering could

  4. Wear Properties of Intermetallic Compound Reinforced Functionally Graded Materials Fabricated by Centrifugal Solid-particle and In-Situ Methods

    NASA Astrophysics Data System (ADS)

    Watanabe, Yoshimi; Sato, Hisashi; Fukui, Yasuyoshi

    One of the functionally graded material (FGM) fabrication methods is a centrifugal method, which is an application of the centrifugal casting technique. The centrifugal force applied to a homogeneous molten composite assists the formation of the desired gradation. In this paper, the wear properties of two kinds of Al base FGMs, namely Al-Al3Ti FGM and Al-Al3Ni FGM, are reported. The former and the latter hold the oriented intermetallic compound platelets and the particle size gradient, respectively. Here, volume fraction, size, shape and orientation of the reinforcements in the composite play an important role in improving the mechanical properties of the materials, whereby FGMs with oriented platelets or particle size gradient may have special mechanical properties such as increased wear resistance. Based on the experimental results, the origin of anisotropic wear resistance and the effect of particle size on the wear properties are discussed.

  5. Magnetic structures of the anisotropic intermetallic compounds Er2CoGa8 and Tm2CoGa8

    NASA Astrophysics Data System (ADS)

    Johnson, R. D.; Frawley, T.; Manuel, P.; Khalyavin, D. D.; Adriano, C.; Giles, C.; Pagliuso, P. G.; Hatton, P. D.

    2010-09-01

    Two members of the isostructural R2CoGa8 intermetallic series, Er2CoGa8 and Tm2CoGa8 , have been studied by powder neutron diffraction. Antiferromagnetic ordering of the rare-earth sublattices was confirmed to occur at 3.0 K and 2.0 K, respectively. Furthermore, determination of the critical exponent showed Er2CoGa8 to adopt a three-dimensional universality class. In spite of a common magnetic easy axis and similar structural characteristics, the antiferromagnetic structures were found to be different for the erbium- and thulium-based compounds. The corresponding magnetic space groups were determined to be P2ammm' and PCmmm . The difference in magnetic structures is discussed based on crystal electric field effects that are known to be prevalent in such materials.

  6. Single crystal growth of Eu2CuSi3 intermetallic compound by the floating-zone method

    NASA Astrophysics Data System (ADS)

    Cao, Chongde; Löser, Wolfgang; Behr, Günter; Klingeler, Rüdiger; Leps, Norman; Vinzelberg, Hartmut; Büchner, Bernd

    2011-03-01

    Large single crystals of the Eu2CuSi3 intermetallic compound have been successfully grown by a vertical floating-zone method with optical heating. Differential thermal analysis reveals that Eu2CuSi3 melts congruently at 1422 °C. The single crystals grown at velocities of 3-5 mm/h show a preferred growth direction close to crystallographic [1 0 0] orientation with inclination angles of about 16-20°. The suppression of evaporation of volatile elements and the control of the floating-zone temperature play a main role in the stability of the growth process. The crystals are Cu-depleted with respect to the nominal Eu2CuSi3 stoichiometry. Both magnetic susceptibility and electrical resistivity measured on oriented single crystalline Eu2CuSi3 samples reveal significant anisotropy with an easy magnetic c-axis and ferromagnetic ordering at TC=34 K.

  7. Interaction of RT 3 (R=Ce, T=Co, Ni, Fe) intermetallic compounds with hydrogen under high pressure

    Microsoft Academic Search

    S. A Lushnikov; S. N Klyamkin; V. N Verbetsky

    2002-01-01

    Interaction in CeCo3–H2, GdFe3–H2 and CeNi2Co–H2 systems with hydrogen under pressure to 2000 atm. has been investigated. Intermetallic compounds CeCo3, GdFe3 and CeNi2Co have CeNi3 or PuNi3 structure type. The maximum compositions of the hydride phases under high pressure CeCo3H6.1, GdFe3H6.1 and CeNi2CoH5.4 have been calculated on the basis of analysis of absorption–desorption isotherms at room temperature. According to X-ray

  8. Fracture Behaviors of Sn-Cu Intermetallic Compound Layer in Ball Grid Array Induced by Thermal Shock

    NASA Astrophysics Data System (ADS)

    Shen, Jun; Zhai, Dajun; Cao, Zhongming; Zhao, Mali; Pu, Yayun

    2014-02-01

    In this work, thermal shock reliability testing and finite-element analysis (FEA) of solder joints between ball grid array components and printed circuit boards with Cu pads were used to investigate the failure mechanism of solder interconnections. The morphologies, composition, and thickness of Sn-Cu intermetallic compounds (IMC) at the interface of Sn-3.0Ag-0.5Cu lead-free solder alloy and Cu substrates were investigated by scanning electron microscopy and transmission electron microscopy. Based on the experimental observations and FEA results, it can be recognized that the origin and propagation of cracks are caused primarily by the difference between the coefficient of thermal expansion of different parts of the packaged products, the growth behaviors and roughness of the IMC layer, and the grain size of the solder balls.

  9. Intermetallic compound layer formation between copper and hot-dipped 100In, 50In50Sn, 100Sn, and 63Sn37Pb coatings

    Microsoft Academic Search

    Paul T. Vianco; Paul F. Hlava; Alice C. Kilgo

    1994-01-01

    The growth kinetics of intermetallic compound layers formed between four hot-dipped solder coatings and copper by solid state,\\u000a thermal aging were examined. The solders were l00Sn, 50In-50Sn, 100In, and 63Sn-37Pb (wt.%); the substrate material was oxygen-free,\\u000a high conductivity Cu. The total intermetallic layer of the 100Sn\\/Cu system exhibited a combination of parabolic growth at\\u000a lower aging temperatures and t0.42 growth

  10. Kinetics of intermetallic compound growth between nickel, electroless, NiP, electroless NiB and tin at 453 to 493 K

    Microsoft Academic Search

    W. J. Tomlinson; H. G. Rhodes

    1987-01-01

    The growth kinetics, crystal structure, and morphology of the intermetallic compounds formed between nickel, electroless Ni-P and electroless Ni-B coatings with tin at 453 to 493 K for times up to 506 h have been determined by microscopical and X-ray diffraction techniques. The compound Ni3Sn4 was formed. All kinetics followed as parabolic law with activation energies of 128.0, 130.4, and

  11. Structure and phase stability of binary zintl-phase compounds: lithium-group 13 intermetallics and metal-doped group 14 clathrate compounds.

    PubMed

    Ker, Alyssa; Todorov, Evgeny; Rousseau, Roger; Uehara, Kentaro; Lannuzel, François-Xavier; Tse, John S

    2002-06-17

    The structure/bonding relationship in a series of intermetallic phases of Li with Al, Ga, and In was investigated by density functional theory and complemented by a model based on tight-binding theory and the method of moments. The combination of these two approaches provides a simple scheme which allows for both a comprehensive understanding of structural trends and the ability to predict low-energy structures for a given composition. This analysis gives a straightforward picture of phase stability in terms of local geometric features such as triangular, square, and hexagonal arrangements of atoms. The approach was extended to examine the structural properties of metal-doped clathrate compounds of C, Si, Ge, and Sn. Clathrate-type phases based on the frameworks Si172, Ge172, Si40, and Ge40 are not only likely to be energetically favorable but may also exhibit high thermoelectric efficiency. PMID:12391658

  12. Synthesis and characterization of patterned surfaces and catalytically relevant binary nanocrystalline intermetallic compounds 

    E-print Network

    Cable, Robert E.

    2008-10-10

    As devices and new technologies continue to shrink, nanocrystalline multi-metal compounds are becoming increasingly important for high efficiency and multifunctionality. However, synthetic methods to make desirable ...

  13. Permanent magnetism of intermetallic compounds between light and heavy transition-metal elements.

    PubMed

    Kumar, P; Kashyap, A; Balamurugan, B; Shield, J E; Sellmyer, D J; Skomski, R

    2014-02-12

    First-principle calculations are used to investigate the intrinsic magnetic properties of intermetallic alloys of the type XMn, where X is a 4d or 5d element and M is Fe or Co. Emphasis is on the hexagonal C14 Laves-phase 1:2 and 1:5 alloys, the latter crystallizing in the CaCu5 structure. These series are of interest in permanent magnetism from fundamental and practical viewpoints, respectively. In the former, the unit cells form a prototypical motif where a heavy atom with high spin-orbit coupling and magnetocrystalline anisotropy is surrounded by many somewhat smaller M atoms with high magnetization, and the latter are Laves-phase derivatives of renewed interest in permanent magnetism. Our DFT calculations predict magnetic moments, magnetizations and anisotropies, as well as formation energies. The results are analyzed across the 4d and 5d series, especially with respect to hybridization effects between 3d and 4d/5d bands. PMID:24469225

  14. Ab-initio calculation of structural, electronic, and optical characterizations of the intermetallic trialuminides ScAl{sub 3} compound

    SciTech Connect

    Hussain Reshak, Ali, E-mail: maalidph@yahoo.co.u [Institute of Physical Biology-South Bohemia University - Nove Hrady 37333 (Czech Republic); Charifi, Z., E-mail: charifi_z@yahoo.f [Physics Department, Faculty of Science and Engineering, University of M'sila, 28000 M'sila (Algeria); Baaziz, H. [Physics Department, Faculty of Science and Engineering, University of M'sila, 28000 M'sila (Algeria)

    2010-06-15

    We present first-principles study of the electronic and the optical properties for the intermetallic trialuminides ScAl{sub 3} compound using the full-potential linear augmented plane wave method within density-functional theory. We have employed the generalized gradient approximation (GGA), which is based on exchange-correlation energy optimization to calculate the total energy. Also we have used the Engel-Vosko GGA formalism, which optimizes the corresponding potential for calculating the electronic band structure and optical properties. The electronic specific heat coefficient ({gamma}), which is a function of density of states, can be calculated from the density of states at Fermi energy N(E{sub F}). The N(E{sub F}) of the phase L1{sub 2} is found to be lower than that of D0{sub 22} structure which confirms the stability of L1{sub 2} structure. We found that the dispersion of the band structure of D0{sub 22} is denser than L1{sub 2} phase. The linear optical properties were calculated. The evaluations are based on calculations of the energy band structure. - Graphical abstract: Crystal structure of L1{sub 2} (a) and D0{sub 22} (b) phases of ScAl{sub 3} compound.

  15. Calculation of the electronic structure of the intermetallic compounds ErNi5 - x Al x ( x = 0, 1, 2)

    NASA Astrophysics Data System (ADS)

    Lukoyanov, A. V.; Knyazev, Yu. V.

    2015-01-01

    The evolution of the electronic structure of the intermetallic compounds ErNi5 - x Al x ( x = 0, 1, 2) with different positions of the substitution of aluminum atoms for nickel atoms has been investigated. For this purpose, spin-polarized calculations of the energy band spectra of these compounds have been performed using the LSDA + U method, which in the local spin density approximation takes into account strong electron correlations in the 4 f shell of the erbium ion. Variants of the substitution of aluminum atoms for nickel atoms in different crystallographic positions in the 3 d sublattice have been considered. An analysis of the band structure has demonstrated that substitutional aluminum impurities lead to the formation of nonmagnetic nickel 3 d states and to a significant decrease in the electron density of states at the Fermi level. A comparison of the total energies of the substitutional configurations has revealed that the occupation of the 3 g positions by aluminum atoms is more energetically favorable.

  16. Complex fragment emission from hot compound nuclei

    SciTech Connect

    Moretto, L.G.

    1986-03-01

    The experimental evidence for compound nucleus emission of complex fragments at low energies is used to interpret the emission of the same fragments at higher energies. The resulting experimental picture is that of highly excited compound nuclei formed in incomplete fusion processes which decay statistically. In particular, complex fragments appear to be produced mostly through compound nucleus decay. In the appendix a geometric-kinematic theory for incomplete fusion and the associated momentum transfer is outlined. 10 refs., 19 figs.

  17. Crystal Structure of the Intermetallic Compound Mg32(AI,Zn)49 and Related Phases

    Microsoft Academic Search

    Gunnar Bergman; John L. T. Waugh; Linus Pauling

    1952-01-01

    PHASE-DIAGRAM studies of the magnesium-aluminium-zinc system have established the existence of a compound with approximate composition Mg3Al2Zn3. Laves, Löhberg and Witte1 reported this compound to have a body-centred cubic structure with a0 = 14.16 A., and with the calculated number of atoms per unit cube equal to 161. They reported also that the phase in the magnesium-aluminium-copper system with approximate

  18. Low-temperature polyol synthesis of AuCuSn2 and AuNiSn2: using solution chemistry to access ternary intermetallic compounds as nanocrystals.

    PubMed

    Leonard, Brian M; Bhuvanesh, Nattamai S P; Schaak, Raymond E

    2005-05-25

    Ternary intermetallic compounds, which possess a wide variety of important properties with both academic and technological relevance, are typically synthesized using traditional high-temperature methods. Here, we demonstrate that the polyol method, which is used extensively to synthesize nanocrystals and nanocrystalline powders of metals and simple binary compounds, serves as an effective low-temperature exploratory medium for synthesizing new ordered ternary intermetallics as nanocrystals. Accordingly, we describe the synthesis and structural characterization of AuCuSn2 and AuNiSn2, which adopt an ordered NiAs-type superstructure that is not observed using equilibrium synthetic methods. AuCuSn2 forms in solution of 120 degrees C as well-formed nanocrystals, and the ordered phase is stable up to 450 degrees C. AuNiSn2 behaves similarly to AuCuSn2. PMID:15898777

  19. A Study on the Effect of Ageing and Intermetallic Compound Growth on the Shear Strength of Surface Mount Technology Solder Joints

    NASA Astrophysics Data System (ADS)

    Nath, Jyotishman; Mallik, Sabuj; Borah, Anil

    2015-04-01

    The effect of ageing and intermetallic compound formation on the surface mount solder joints and its shear strength behavior under extreme mechanical and thermal conditions have been discussed in this paper. The specimens used are solder paste (Sn3.8Ag0.7Cu), bench marker II printed circuit boards (PCB), resistors 1206 and the fabrication of solder joints makes use of conventional surface mount technology (SMT). Reflow process was carried out at a peak temperature of 250 °C and the test samples were exposed to isothermal ageing at a constant temperature of 150 °C for a period of 600 h. Shear test was conducted on the PCB's. The shear strength of the solder joints rapidly increased during isothermal ageing to a certain time period and then started decreasing. Field emission scanning electron microscopy (FESEM) micrograph of the solder joint and energy dispersive X-ray (EDX) was performed on the solder sample to verify the formation of intermetallic compounds.

  20. JOURNAL DE PHYSIQUE Colloque C4, supplment au n" 4, Tome 40, avril 1979, page C4-82 Magnetic and magnetoelastic properties of the UGa2 intermetallic compound

    E-print Network

    Paris-Sud XI, Université de

    and magnetoelastic properties of the UGa2 intermetallic compound A. V. Andreev (*), K. P. Belov (**), A. V. Deriagin and available at http://dx.doi.org/10.1051/jphyscol:1979427 #12;MAGNETIC AND MAGNETOELASTIC PROPERTIES C4

  1. Synthesis of ultrafine particles of intermetallic compounds by the vapor-phase magnesium reduction of chloride mixtures: Part II. Nickel aluminides

    Microsoft Academic Search

    H. Y. Sohn; S. Paldey

    1998-01-01

    The new chemical synthesis process developed in this laboratory for the preparation of the fine powders of intermetallic compounds\\u000a by the vapor-phase reduction of mixtures of constituent metal chlorides by magnesium vapor, described in Part I for titanium\\u000a aluminides, was applied to the synthesis of nickel aluminide particles. NiAl, NiAl3, and Ni2Al3 were formed by reducing mixtures of NiCl2 and

  2. Effect of calcium on intermetallic compound layer at interface of calcium added magnesium–aluminum alloy and titanium joint by friction stir welding

    Microsoft Academic Search

    Masayuki Aonuma; Kazuhiro Nakata

    2010-01-01

    Commercial AMCa602 alloy (Mg–6% Al–2% Ca) and AM60 alloy (Mg–6% Al) were joined to titanium plates by friction stir welding to evaluate the effect of a calcium on the reaction layer at the dissimilar joint interface and the joint tensile strength. At the titanium and AM60 joint interface, a TiAl3 intermetallic compound layer was formed. The thickness of this layer

  3. Intermetallic compound layer development during the solid state thermal aging of 63Sn37Pb solder\\/Au-Pt-Pd thick film couples

    Microsoft Academic Search

    Paul T. Vianco; John J. Stephens; Jerome A. Rejent

    1997-01-01

    A study was performed which examined the solid state, intermetallic compound layer growth kinetics between 63Sn-37Pb solder and a 76Au-21Pt-3Pd (wt.%) thick film conductor on 96% alumina substrates. A linear, multivariable regression analysis was used to assess the experimental data according to the following empirical relationship: x-x0=Atn exp(-?H\\/RT). A time exponent of n=0.78±0.08 was observed, suggesting that a combination of

  4. Electrical and thermal transport properties of intermetallic RCoGe2 (R = Ce and La) compounds.

    PubMed

    Ramachandran, B; Chang, P C; Kuo, Y K; Lue, C S

    2014-06-25

    To investigate the electronic structure of the intermetallic compound CeCoGe2, we performed electrical resistivity (?), Seebeck coefficient (S), and thermal conductivity (?) measurements in a temperature range of 10-300?K. For comparison, the non-magnetic counterpart LaCoGe2 is also studied. It is found that CeCoGe2 exhibits a broad maximum in the S(T) near 75?K, at which the sudden drop in the ?(T) is observed. Temperature-dependent electrical resistivity and the Seebeck coefficient of CeCoGe2 can be described well by a two-band model, which reveals the signature of Kondo scattering in CeCoGe2. On the other hand, a typical metallic-like behavior is seen in the non-magnetic LaCoGe2 from the ?(T) and S(T) studies. Analysis of the thermal conductivity indicates that the electronic contribution dominates thermal transport above 100?K in both CeCoGe2 and LaCoGe2. In addition, it is found that the variation in low-temperature lattice thermal conductivity of CeCoGe2 as compared to that of LaCoGe2 is most likely due to the phonon-point-defect scattering. PMID:24861445

  5. Synthesis, crystal structure, and magnetic properties of novel intermetallic compounds R2Co2SiC (R = Pr, Nd).

    PubMed

    Zhou, Sixuan; Mishra, Trinath; Wang, Man; Shatruk, Michael; Cao, Huibo; Latturner, Susan E

    2014-06-16

    The intermetallic compounds R2Co2SiC (R = Pr, Nd) were prepared from the reaction of silicon and carbon in either Pr/Co or Nd/Co eutectic flux. These phases crystallize with a new stuffed variant of the W2CoB2 structure type in orthorhombic space group Immm with unit cell parameters a = 3.978(4) Å, b = 6.094(5) Å, c = 8.903(8) Å (Z = 2; R1 = 0.0302) for Nd2Co2SiC. Silicon, cobalt, and carbon atoms form two-dimensional flat sheets, which are separated by puckered layers of rare-earth cations. Magnetic susceptibility measurements indicate that the rare earth cations in both analogues order ferromagnetically at low temperature (TC ? 12 K for Nd2Co2SiC and TC ? 20 K for Pr2Co2SiC). Single-crystal neutron diffraction data for Nd2Co2SiC indicate that Nd moments initially align ferromagnetically along the c axis around ?12 K, but below 11 K, they tilt slightly away from the c axis, in the ac plane. Electronic structure calculations confirm the lack of spin polarization for Co 3d moments. PMID:24898034

  6. Micromagnetic analysis of the hardening mechanisms of nanocrystalline MnBi and nanopatterned FePt intermetallic compounds.

    PubMed

    Kronmüller, H; Yang, J B; Goll, D

    2014-02-12

    The uniaxial intermetallic compounds of L10-FePt and the low temperature NiAs structure of MnBi are suitable alloys for application as high-density recording materials or as high-coercivity permanent magnets. Single domain particles of these materials are characterized by coercive fields above 1 T over a large temperature range. In particular MnBi shows a coercive field of 2 T at 450 K. Its extraordinary magnetic properties in the temperature range up to 600 K are due to an increase of the magnetocrystalline anisotropy constant from 1.2 MJ m(-3) at 300 K to 2.4 MJ m(-3) at 450 K. In spite of the large coercivities obtained for both type of materials their experimental values deviate considerably from the theoretical values Hc = 2K1/Js valid for a homogeneous rotation process in spherical particles. As is well known these discrepancies are due to the deteriorating effects of the microstructure. For an analysis of the coercive fields the Stoner-Wohlfarth theory has to be expanded with respect to higher anisotropy constants and to microstructural effects such as misaligned grains and grain surfaces with reduced anisotropy constants. It is shown that the temperature dependence and the angular dependence of Hc for FePt as well as MnBi can be quantitatively interpreted by taking into account the above mentioned intrinsic and microstructural effects. PMID:24469256

  7. Formation of intermetallic compound layer in multi-laminated Ni-(TiB2/Al) composite sheets during annealing treatment.

    PubMed

    Wang, Q W; Fan, G H; Geng, L; Zhang, J; Zhang, Y Z; Cui, X P

    2013-02-01

    Solid-state reactive diffusion between Ni and Al was investigated during annealing at 650°C by employing multi-laminated Ni-(TiB(2)/Al) composite sheets. In multi-laminated Ni-(TiB(2)/Al) composite sheets annealed up to 5min NiAl(3) was the only phase observed in the diffusion zone, and Ni(2)Al(3) appeared after longer annealing time. Most grains of Ni(2)Al(3) showed equiaxed morphology rather than columnar microstructures like NiAl(3), due to the low concentration gradients of Al and Ni at the Ni/NiAl(3) interface. The preferential formation of this intermetallic compound NiAl(3) in multi-laminated Ni-(TiB(2)/Al) composite sheets was predicted using an effective heat of formation model. The present work indicated that both Ni and Al interdiffused, and the formation of NiAl(3) was a reaction-diffusion process. PMID:23266224

  8. In situ study on the effect of thermomigration on intermetallic compounds growth in liquid-solid interfacial reaction

    SciTech Connect

    Qu, Lin; Zhao, Ning; Ma, Haitao, E-mail: htma@dlut.edu.cn; Zhao, Huijing; Huang, Mingliang [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116085 (China)

    2014-05-28

    Synchrotron radiation real-time imaging technology was carried out in situ to observe and characterize the effect of thermomigration on the growth behavior of interfacial intermetallic compounds (IMCs) in Cu/Sn/Cu solder joint during soldering. The thermomigration resulted in asymmetrical formation and growth of the interfacial IMCs. Cu{sub 6}Sn{sub 5} and Cu{sub 3}Sn IMCs formed at the cold end and grew rapidly during the whole soldering process. However, only Cu{sub 6}Sn{sub 5} IMC formed at the hot end and remained relatively thin until solidification. The IMCs at the cold end were nearly seven times thicker than that at the hot end after solidification. The Cu dissolution at the cold end was significantly restrained, while that at the hot end was promoted, which supplied Cu atoms to diffuse toward the cold end under thermomigration to feed the rapid IMC growth. Moreover, the thermomigration also caused asymmetrical morphology of the interfacial IMCs at the cooling stage, i.e., the Cu{sub 6}Sn{sub 5} IMC at the cold end transformed into facet structure, while that at the hot end remained scallop-type. The asymmetrical growth behavior of the interfacial IMCs was analyzed from the view point of kinetics.

  9. Environmental effects in niobium-base alloys and other selected intermetallic compounds. Final report, 1 Jan 87-31 Oct 90

    SciTech Connect

    Meier, G.H.; Thompson, A.W.

    1991-04-30

    Niobium aluminides and silicides as well as other intermetallic compounds have potential for use in advanced gas turbines where increased operating temperatures are necessary to obtain the targeted performance goals. These materials will be subjected to a variety of environments over a range of temperatures. Two of the principal reactants in these environments are oxygen and hydrogen. This program has been concerned with the effects of oxygen and hydrogen on niobium alloys and other selected intermetallic compounds. The investigations involving oxygen examined the mechanisms by which intermetallic compounds are degraded in oxidizing environments. Emphasis was placed upon the conditions which must be achieved in order to obtain sufficient oxidation resistance for use at temperatures above about 1100 deg C. Oxidation was investigated at temperatures between 500 and 1400 C in oxygen and in air. Investigations involving hydrogen have emphasized brittle fracture, crack growth and the behavior of hydrides in Ti-24Al-11Nb (at. %). Some work of this type was also performed on TiAl. The mechanical properties of these alloys were determined after exposure to hydrogen. Mechanical tests included simple tensile and compression tests, and notched bend and precracked compact tension specimens. Properties such as yield strength and ultimate strength, tensile strength, ductility, and fracture toughness have been determined as a function of both hydrogen (hydride) content and temperature.

  10. Effect of heating rate on the combustion synthesis of Ti-Al intermetallic compounds

    Microsoft Academic Search

    H. C. Yi; A. Petric; J. J. Moore

    1992-01-01

    Titanium aluminide compounds were synthesized by the thermal explosion mode of self-propagating high-temperature synthesis (SHS). The effects of heating rate on the combustion characteristics and the microstructures of the products were studied. It was found that the low density of the reacted sample was due to the outgassing of water vapour and other gases, which were released by dissociation of

  11. Low-temperature solution synthesis of alloys and intermetallic compounds as nanocrystals

    E-print Network

    Vasquez, Yolanda

    2009-05-15

    were synthesized via solution techniques where metal compounds are reduced by NaBH4 or n-butyllithium at temperatures below 300°C. To form hollow particles, metal nanoparticles of Co, Ni, Pb were synthesized via reduction by NaBH4 in water and reacted...

  12. Effect of pressure on structural properties of intermetallic LnM lanthanide compounds

    Microsoft Academic Search

    V. F. Degtyareva; F. Porsch; S. S. Khasanov; V. Sh. Shekhtman; W. B. Holzapfel

    1997-01-01

    Energy dispersive powder X-ray diffraction measurements with diamond anvil high pressure cells at ambient temperature and pressure up to 50 GPa on the LnM compounds GdCu, LaAg, NdAg, NdZn, CeZn and LaZn show systematically high pressure phase transformations from the cP2 (CsCl-type) structure to lower symmetry phases, however, with only minor effects from valence instabilities.

  13. Effect of chemical and external pressure on the structure of intermetallic compound CeNi

    Microsoft Academic Search

    A. Mirmelstein; E. Clementyev; V. Voronin; Yu. Akshentsev; D. Kozlenko; A. Kutepov; A. Petrovtsev; Yu. Zuev

    2007-01-01

    Neutron powder diffraction was employed to study the structural modifications of the intermediate-valence compound CeNi at room temperature induced by either chemical or external pressure. For the first time we were able to record the diffraction pattern resulting from the pressure-induced first-order phase transition occurring in CeNi at 300K. At pressure P=2GPa we observe the coexistence of two phases while

  14. Electronic properties of Hf 2 X intermetallic compounds (X = Al, Si, Ni, Ga and Ge)

    Microsoft Academic Search

    I. Yaar; I. Halevy; S. Kahane; A. Beck; Z. Berant

    2007-01-01

    The electric field gradient (EFG) parameters were calculated for the binary system Hf2X (X = Al, Si, Ni, Ga and Ge), using the full-potential linear augmented plane wave method, applying the generalized gradient\\u000a approximation. The major contribution to the EFG value in these compounds comes from the p–p contribution next to the probe\\u000a nucleus. The only other significant contribution is

  15. Electronic properties of Hf2X intermetallic compounds (X =Al, Si, Ni, Ga and Ge)

    Microsoft Academic Search

    I. Yaar; I. Halevy; S. Kahane; A. Beck; Z. Berant

    2008-01-01

    The electric field gradient (EFG) parameters were calculated for the binary system Hf2X (X =Al, Si, Ni, Ga and Ge), using the full-potential linear augmented plane wave method, applying the generalized gradient approximation. The major contribution to the EFG value in these compounds comes from the p-p contribution next to the probe nucleus. The only other significant contribution is a

  16. Icosahedral quasicrystals of intermetallic compounds are icosahedral twins of cubic crystals of three kinds, consisting of large (about 5000 atoms) icosahedral complexes in either a cubic body-centered or a cubic face-centered arrangement or smaller (about 1350 atoms) icosahedral complexes in the ?-tungsten arrangement

    PubMed Central

    Pauling, Linus

    1989-01-01

    The twofold-axis electron-diffraction photographs of icosahedral quasicrystals are of three kinds, reflecting three different structures of the cubic crystals that by icosahedral twinning form the quasicrystals. The first kind, represented by Al13Cu4Fe3, contains two very large icosahedral complexes, each of about 4680 atoms, in the body-centered arrangement, with six smaller icosahedral complexes (104 atoms each) in the principal interstices. The second kind, represented by Al5Mn, contains four of the very large complexes in the face-centered arrangement (cubic close packing), with four of the smaller clusters in the interstices. The third kind, represented by Al6CuLi3, contains eight icosahedral complexes, each of about 1350 atoms, in the ?-W arrangement. The supporting evidence for these cubic structures is discussed as well as other evidence showing that the simple quasicrystal theory, which states that quasicrystals do not involve any translational identity operations, has to be modified. Images PMID:16594078

  17. Crystal structure of the inter­metallic compound SrCdPt

    PubMed Central

    Gulo, Fakhili; Köhler, Jürgen

    2014-01-01

    The crystal structure of the title compound, strontium cadmium platinum, adopts the TiNiSi structure type with the Sr atoms on the Ti, the Cd atoms on the Ni and the Pt atoms on the Si positions, respectively. The Pt atoms form cadmium-centred tetra­hedra that are condensed into a three-dimensional network with channels parallel to the b-axis direction in which the Sr atoms are located. The latter are bonded to each other in the form of six-membered rings with chair conformations. All atoms in the SrCdPt structure are situated on a mirror plane. PMID:25553000

  18. Crystal structure of the inter-metallic compound SrCdPt.

    PubMed

    Gulo, Fakhili; Köhler, Jürgen

    2014-12-01

    The crystal structure of the title compound, strontium cadmium platinum, adopts the TiNiSi structure type with the Sr atoms on the Ti, the Cd atoms on the Ni and the Pt atoms on the Si positions, respectively. The Pt atoms form cadmium-centred tetra-hedra that are condensed into a three-dimensional network with channels parallel to the b-axis direction in which the Sr atoms are located. The latter are bonded to each other in the form of six-membered rings with chair conformations. All atoms in the SrCdPt structure are situated on a mirror plane. PMID:25553000

  19. Effect of severe plastic deformation on the structure and crystal-lattice distortions in the Ni3(Al, X) ( X = Ti, Nb) intermetallic compound

    NASA Astrophysics Data System (ADS)

    Kazantseva, N. V.; Pilyugin, V. P.; Danilov, S. E.; Kolosov, V. Yu.

    2015-05-01

    A systematic combined study of crystal lattice distortions caused by doping and by severe plastic deformation (SPD) of Ti- and Nb-doped Ni3Al intermetallic compound has been carried out using methods of X-ray diffraction, electron microscopy, and electrical-resistance measurements. The degree of imperfection of the alloys has been estimated based on the results obtained by all three methods. The degree of structural perfection of niobium-doped crystals was found to be higher than in the case of Ti doping. The character of stresses (tensile stresses after doping; and compressive stresses after SPD) in the crystal lattice has been established and their values have been calculated. A significant increase in the density of dislocations, point defects, and lattice curvature has been found after SPD. A nanocrystalline structure is formed in these alloys, but no complete disordering of the intermetallic phase is observed.

  20. Crystallographic characterization of some intermetallic compounds in the Al-Cr system

    NASA Astrophysics Data System (ADS)

    Bendersky, L. A.; Roth, R. S.; Ramon, J. T.; Shechtman, D.

    1991-01-01

    Two Al-Cr compounds, known in the literature as the ? and ? phases, were studied by precession camera single crystal X-ray diffraction and transmission electron microscopy (TEM). The results are different from those reported in the literature. The ? Al4Cr phase was found to be hexagonal P63/mmc with lattice parameters a=2.01 nm and c=2.48 nm, and we suggest that it is isomorphous to the Al4Mn ? phase. The ? Al11Cr2 phase has a monoclinic (pseudo-orthorhombic) C-centered Bravais lattice with a 3?1.76 nm, b 3?3.05 nm, c 3?1.76 nm, and ??90 deg and a possible C2/c space group. Single crystals of the ? phase are usually twinned.

  1. Electronic structure of RNiC2 ( R=Sm , Gd, and Nd) intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Laverock, J.; Haynes, T. D.; Utfeld, C.; Dugdale, S. B.

    2009-09-01

    First-principles calculations of the electronic structure of members of the RNiC2 series are presented and their Fermi surfaces investigated for nesting propensities, which might be linked to the charge-density waves exhibited by certain members of the series ( R=Sm , Gd, and Nd). Calculations of the generalized susceptibility, ?0(q,?) , show strong peaks at the same q vector in both the real and imaginary parts for these compounds. Moreover, this peak occurs at a wave vector which is very close to that experimentally observed in SmNiC2 . In contrast, for LaNiC2 (which is a superconductor below 2.7 K) as well as for ferromagnetic SmNiC2 , there is no such sharp peak. This could explain the absence of a charge-density wave transition in the former, and the destruction of the charge-density wave that has been observed to accompany the onset of ferromagnetic order in the latter.

  2. Electronic packing frustration in complex intermetallic structures: the role of chemical pressure in Ca2Ag7.

    PubMed

    Fredrickson, Daniel C

    2011-07-01

    The assignment of distinct roles to electronics and sterics has a long history in our rationalization of chemical phenomena. Exploratory synthesis in the field of intermetallic compounds challenges this dichotomy with a growing list of phases whose structural chemistry points to an interplay between atomic size effects and orbital interactions. In this paper, we begin with a simple model for how this interdependence may arise in the dense atomic packing of intermetallics: correlations between interatomic distances lead to the inability of a phase to optimize bonds without simultaneously shortening electronically under-supported contacts, a conflict we term electronic packing frustration (EPF). An anticipated consequence of this frustration is the emergence of chemical pressures (CPs) acting on the affected atoms. We develop a theoretical method based on DFT-calibrated ?(2)-Hückel calculations for probing these CP effects. Applying this method to the Ca(2)Ag(7) structure, a variant of the CaCu(5) type with defect planes, reveals its formation is EPF-driven. The defect planes resolve severe CPs surrounding the Ca atoms in a hypothetical CaCu(5)-type CaAg(5) phase. CP analysis also points to a rationale for these results in terms of a CP analogue of the pressure-distance paradox and predicts that the impetus for defect plane insertion is tunable via variations in the electron count. PMID:21619054

  3. Fragmentation of the fluorite type in Fe8Al(17.4)Si(7.6): structural complexity in intermetallics dictated by the 18 electron rule.

    PubMed

    Fredrickson, Rie T; Fredrickson, Daniel C

    2012-10-01

    This Article presents the synthesis, structure determination, and bonding analysis of Fe(8)Al(17.4)Si(7.6). Fe(8)Al(17.4)Si(7.6) crystallizes in a new monoclinic structure type based on columns of the fluorite (CaF(2)) structure type. As such, the compound can be seen as part of a structural series in which the fluorite structure-adopted by several transition metal disilicides (TMSi(2))-is fragmented by the incorporation of Al. Electronic structure analysis using density functional theory (DFT) and DFT-calibrated Hückel calculations indicates that the fluorite-type TMSi(2) phases (TM = Co, Ni) exhibit density of states (DOS) pseudogaps near their Fermi energies. An analogous pseudogap occurs for Fe(8)Al(17.4)Si(7.6), revealing that its complex structure serves to preserve this stabilizing feature of the electronic structure. Pursuing the origins of these pseudogaps leads to a simple picture: the DOS minimum in the TMSi(2) structures arises via a bonding scheme analogous to those of 18 electron transition metal complexes. Replacement of Si with Al leads to the necessity of increasing the (Si/Al):TM ratio to maintain this valence electron concentration. The excess Si/Al atoms are accommodated through the fragmentation of the fluorite type. The resulting picture highlights how the elucidating power of bonding concepts from transition metal complexes can extend into the intermetallic realm. PMID:22984870

  4. Evolution and Stability of a Nanocrystalline Cu3Ge Intermetallic Compound Fabricated by Means of High Energy Ball Milling and Annealing Processes

    NASA Astrophysics Data System (ADS)

    Nazarian-Samani, Mahboobeh; Kamali, Ali Reza; Nazarian-Samani, Masoud; Kashani-Bozorg, Seyed Farshid

    2015-01-01

    In this study, the structural evolution of two nanostructured Cu-22 wt pct Ge (Cu-20 at. pct Ge) and Cu-26 wt pct Ge (Cu-24 at. pct Ge) alloys upon mechanical alloying (MA) with subsequent heat treatment was investigated, and the phase transitions were monitored by means of various characterization methods. The findings indicated that, when the MA process continued for some time, a nanocrystalline ?-Cu(Ge) solid solution was formed, which partially transformed into an amorphous phase. Further MA processing for 20 hours led to the formation of a disordered nanometric ?-Cu3Ge intermetallic compound with a monoclinic crystal structure. Increased milling time subsequently led to the diminishing of the content of the amorphous phase which transformed into ?-Cu3Ge nanocrystals. Clearly, a nanocrystallization transformation occurred upon ball milling principally on account of the accumulated energy due to the heavy mechanical deformation. Crystallization was also seen to occur at 473 K (200 °C) after annealing the MA-ed powders, leading to the formation of an ordered ? 1-Cu3Ge intermetallic phase with an orthorhombic structure. The crystallographic relationships between the two disordered and ordered intermetallic phases were also discussed.

  5. Atomic disorder and phase transformation in intermetallic compounds of the type T3X2 (T=Ni,Fe,Mn; X=Sn,Ge) by mechanical milling

    Microsoft Academic Search

    G. F. Zhou; H. Bakker

    1994-01-01

    The structural development of the ordered intermetallic compounds T3X2 (T=Ni,Fe,Mn; X=Sn,Ge) upon mechanical milling was investigated by x-ray diffraction, magnetic measurements, and subsequently by differential scanning calorimetry (DSC). It is found that the magnetization at 4.2 K increases continuously with increasing milling time in ferromagnetic Ni3Sn2 and Fe3Ge2. In contrast, in ferrimagnetic Mn3Sn2 it decreases. The unit-cell volume of both

  6. Effect of Ag addition on the structures of intermetallic compounds and the adhesion strength of the Sn–9Zn– xAg\\/Cu interface

    Microsoft Academic Search

    Tao-Chih Chang; Moo-Chin Wang; Min-Hsiung Hon

    2003-01-01

    The effect of Ag addition on the structures of the intermetallic compounds (IMCs) and the adhesion strength of the Sn–9Zn–xAg solder alloy\\/Cu interface has been investigated by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry, transmission electron microscopy and electron diffraction. The XRD patterns show that the ?-Cu6Sn5, ??-Cu6Sn5 and Cu5Zn8 are found at the Sn–9Zn–xAg\\/Cu interface. The Ag3Sn formed

  7. Different Cation Arrangements in Au-In Networks. Syntheses and Structures of Six Intermetallic compounds in Alkali-Metal-Au-In Systems

    Microsoft Academic Search

    Bin Li; John D. Corbett

    2007-01-01

    Six robust intermetallic compounds with cations in three different tunnel-like structures have been synthesized in alkali-metal-Au-In systems via high-temperature solid-state methods and characterized by X-ray diffraction: AAu-In [A = K (I), Rb (II), F6m2, Z = 1], K{sub 1.76(6)}AuLn (III, \\/4\\/mcm, Z = 4), and AAuIn [x 0.7, A = K (IV), Rb (V), Cs (VI), P4\\/nmc, Z = 8].

  8. Electrocatalytic mechanism and kinetics of SOMs oxidation on ordered PtPb and PtBi intermetallic compounds: DEMS and FTIRS study.

    PubMed

    Wang, Hongsen; Alden, Laif; Disalvo, F J; Abruña, Héctor D

    2008-07-01

    The electrocatalytic activities and mechanisms of PtPb and PtBi ordered intermetallic phases towards formic acid, formaldehyde and methanol oxidation have been studied by DEMS and FTIRS, and the results compared to those for a pure polycrystalline platinum electrode. While PtPb exhibits an enhanced electrocatalytic activity for the oxidation of all three organic molecules when compared to a Pt electrode, PtBi exhibits an enhanced catalytic activity towards formic acid and formaldehyde oxidation, but not methanol. FTIRS data indicate that adsorbed CO does not form on PtPb or PtBi intermetallic compounds during the oxidation of formic acid, formaldehyde and methanol, and therefore their oxidation on both PtPb and PtBi intermetallic compounds proceeds via a non-CO(ads) pathway. Quantitative DEMS measurements indicate that only CO(2) was detected as a final product during formic acid oxidation on Pt, PtPb and PtBi electrodes. At a smooth polycrystalline platinum electrode, the oxidation of formaldehyde and methanol produces mainly intermediates (formaldehyde and formic acid), while CO(2) is a minor product. In contrast, CO(2) is the major product for formaldehyde and methanol oxidation at a PtPb electrode. The high current efficiency of CO(2) formation for methanol and formaldehyde oxidation at a PtPb electrode can be ascribed to the complete dehydrogenation of formaldehyde and formic acid due to electronic effects. The low onset potential, high current density and high CO(2) yield make PtPb one of the most promising electrocatalysts for fuel cell applications using small organic molecules as fuels. PMID:18563235

  9. Structural, stability and electronic properties of C15-AB2 (A = Ti, Zr; B = Cr) intermetallic compounds and their hydrides: An ab initio study

    NASA Astrophysics Data System (ADS)

    Sarhaddi, Reza; Arabi, Hadi; Pourarian, Faiz

    2014-05-01

    The structural, stability and electronic properties of C15-AB2 (A = Ti, Zr; B = Cr) isomeric intermetallic compounds were systematically investigated by using density functional theory (DFT) and plane-wave pseudo-potential (PW-PP) method. The macroscopic properties including the lattice constant, bulk modulus and stability for these compounds were studied before and after hydrogenation. For parent compounds, the enthalpy of formation was evaluated with regard to their bulk modules and electronic structures. After hydrogenation of compounds at different interstitial tetrahedral sites (A2B2, A1B3, B4), a volume expansion was found for hydrides. The stability properties of hydrides characterized the A2B2 sites as the site preference of hydrogen atoms for both compounds. The Miedema's "reverse stability" rule is also satisfied in these compounds as lower the enthalpy of formation for the host compound, the more stable the hydride. Analysis of microscopic properties (electronic structures) after hydrogenation at more stable interstitial site (A2B2) shows that the H atoms interact stronger with the weaker (or non) hydride forming element B (Cr) than the hydride forming element A (Ti/Zr). A correlation was also found between the stability of the hydrides and their electronic structure: the deeper the hydrogen band, the less stable the hydride.

  10. A new complex intermetallic phase in the system Al-Cu-Ta with familiar clusters and packing principles.

    PubMed

    Dshemuchadse, Julia; Bigler, Sandro; Simonov, Arkadiy; Weber, Thomas; Steurer, Walter

    2013-06-01

    The structure of hP386-Al(57.4)Cu(3.6)Ta(39.0) was determined by single-crystal X-ray diffraction analysis. It can be described as a hexagonal close-packing of two types of endohedral fullerene-like clusters with different Frank-Kasper polyhedra filling the gaps. The description of the structure as a superstructure and as a layered structure illustrates other characteristic structural building principles. The diffuse scattering, which can be observed in some of the crystals, is qualitatively well reproduced by a disorder model. A comparison with the structures of the other complex intermetallics in the system Al-Cu-Ta indicates the decisive role that Cu plays in the constitution and packing of the clusters. PMID:23719468

  11. Calculation of electronic structure and mechanical properties of DO3-Fe75-xSi25Nix intermetallic compounds by first principles

    NASA Astrophysics Data System (ADS)

    Ma, R.; Wan, M. P.; Huang, J.; Xie, Q.

    2015-04-01

    Based on the density functional theory (DFT), the plane-wave pseudopotential method was used to investigate the electronic structures and mechanical properties of DO3-Fe75-xSi25Nix(x = 0, 3.125, 6.25 and 9.375) intermetallic compounds. The elastic parameters were calculated, and then the bulk modulus, shear modulus and elastic modulus were derived. The paper then focuses on the discussion of ductility and plasticity. The results show that by adding appropriate Ni to Fe3Si intermetallic compound can improve the ductility. But the hardness will increase when the Ni content exceeds 6.25%. Analysis of density of states (DOS) and overlap populations indicates that with the difference of the strength of bonding and activity, there were some differences of ductility among different Ni contents. The Fe71.875Ni3.125Si25 has the lowest hardness because the covalent bonding (Fe-Si bond and Si-Ni bond) has the minimum covalent electrons.

  12. Interfacial reaction of intermetallic compounds of ultrasonic-assisted brazed joints between dissimilar alloys of Ti6Al4V and Al4Cu1Mg.

    PubMed

    Ma, Zhipeng; Zhao, Weiwei; Yan, Jiuchun; Li, Dacheng

    2011-09-01

    Ultrasonic-assisted brazing of Al4Cu1Mg and Ti6Al4V using Zn-based filler metal (without and with Si) has been investigated. Before brazing, the Ti6Al4V samples were pre-treated by hot-dip aluminizing and ultrasonic dipping in a molten filler metal bath in order to control the formation of intermetallic compounds between the Ti6Al4V samples and the filler metal. The results show that the TiAl(3) phase was formed in the interface between the Ti6Al4V substrate and the aluminized coating. For the Zn-based filler metal without Si, the Ti6Al4V interfacial area of the brazed joint did not change under the effect of the ultrasonic wave, and only consisted of the TiAl(3) phase. For the Zn-based filler metal with Si, the TiAl(3) phase disappeared and a Ti(7)Al(5)Si(12) phase was formed at the interfacial area of the brazed joints under the effect of the ultrasonic wave. Due to the TiAl(3) phase completely changing to a Ti(7)Al(5)Si(12) phase, the morphology of the intermetallic compounds changed from a block-like shape into a lamellar-like structure. The highest shear strength of 138MPa was obtained from the brazed joint free of the block-like TiAl(3) phase. PMID:21489846

  13. The early stage dissolution of Ni and the nucleation of Ni-Sn intermetallic compound at the interface during the soldering of Sn-3.5Ag on a Ni substrate

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Wei; Lin, Kwang-Lung

    2010-09-01

    The early stage soldering reaction, reflow for 5 s at 250 °C followed by a liquid nitrogen quench, of Sn-3.5Ag on an electroplated Ni substrate gives rise to a Ni dissolution zone, an amorphous Ni-Sn diffusion zone, and nuclei of NiSn intermetallic compound within the interfacial region. The nucleation of NiSn takes place at the interface between the dissolution zone and the amorphous diffusion zone as well as within the amorphous Ni-Sn diffusion zone, producing 10 nm nanocrystallites. High resolution transmission electron microscope observations indicate that NiSn is the preliminary intermetallic compound that forms during the soldering reaction.

  14. Low complexity guaranteed fit compound document compression

    Microsoft Academic Search

    Debargha Mukherjee; Christos Chrysafis; Amir Said

    2002-01-01

    We propose a new, very low complexity, single-pass, algorithm for compression of continuous tone compound documents, known as GRAFIT (GuaRAnteed FIT) that can guarantee a minimum compression ratio of as much as 12:1 and even more, for all images in a single pass, while maintaining visually lossless quality when reproduced at resolution 300 dpi or more. The compression ratio is

  15. Application of Time Domain Reflectometry in Evaluating Irregular Intermetallic Compound Growth in Gold Wire Bonds Encapsulated with Green Epoxy Mold Compound

    Microsoft Academic Search

    Jason Wong; A. Seah; S. Chew

    2007-01-01

    In this paper, we have successfully used the comparative TDR technique as a means to detect and locate intermittent electrical failures in various packaged devices caused by weak interconnect interfaces or transmission traces that are degraded due to electromigration or intermetallic diffusion processes. A series of different common fail signatures from the resultant TDR waveforms can be correlated with cross

  16. Comparison of Sn-Ag-Cu Solder Alloy Intermetallic Compound Growth Under Different Thermal Excursions for Fine-Pitch Flip-Chip Assemblies

    NASA Astrophysics Data System (ADS)

    Tian, Ye; Liu, Xi; Chow, Justin; Wu, Yi Ping; Sitaraman, Suresh K.

    2013-08-01

    The intermetallic compound (IMC) evolution in Cu pad/Sn-Ag-Cu solder interface and Sn-Ag-Cu solder/Ni pad interface was investigated using thermal shock experiments with 100- ?m-pitch flip-chip assemblies. The experiments show that low standoff height of solder joints and high thermomechanical stress play a great role in the interfacial IMC microstructure evolution under thermal shock, and strong cross-reaction of pad metallurgies is evident in the intermetallic growth. Furthermore, by comparing the IMC growth during thermal aging and thermal shock, it was found that thermal shock accelerates IMC growth and that kinetic models based on thermal aging experiments underpredict IMC growth in thermal shock experiments. Therefore, new diffusion kinetic parameters were determined for the growth of (Cu,Ni)6Sn5 using thermal shock experiments, and the Cu diffusion coefficient through the IMC layer was calculated to be 0.2028 ?m2/h under thermal shock. Finite-element models also show that the solder stresses are higher under thermal shock, which could explain why the IMC growth is faster and greater under thermal shock cycling as opposed to thermal aging.

  17. Icosahedral and decagonal quasicrystals of intermetallic compounds are multiple twins of cubic or orthorhombic crystals composed of very large atomic complexes with icosahedral point-group symmetry in cubic close packing or body-centered packing: Structure of decagonal Al6Pd

    PubMed Central

    Pauling, Linus

    1989-01-01

    A doubly icosahedral complex involves roughly spherical clusters of atoms with icosahedral point-group symmetry, which are themselves, in parallel orientation, icosahedrally packed. These complexes may form cubic crystallites; three structures of this sort have been identified. Analysis of electron diffraction photographs of the decagonal quasicrystal Al6Pd has led to its description as involving pentagonal twinning of an orthorhombic crystal with a = 51.6 Å, b = 37.6 Å, and c = 33.24 Å, with about 4202 atoms in the unit, comprising two 1980-atom doubly icosahedral complexes, each involving icosahedral packing of 45 44-atom icosahedral complexes (at 0 0 0 and 1/2 1/2 1/2) and 242 interstitial atoms. The complexes and clusters are oriented with one of their fivefold axes in the c-axis direction. Images PMID:16594092

  18. Magnetic ordering in the rare earth intermetallic compound Tb2Ti3Ge4: Magnetization and neutron diffraction studies

    SciTech Connect

    Malik, S. K. [University of Brasilia, Brasilia; Lamsal, Jagat [University of Missouri, Columbia; Yelon, W. B. [Missouri University of Science and Technology; Morozkin, A. V. [Moscow Lomonosov State University; Nirmala, R. [Indian Institute of Technology, Madras

    2009-01-01

    Magnetization and neutron diffraction studies on a polycrystalline Tb2Ti3Ge4 sample (orthorhombic Sm5Ge4-type structure, space group Pnma, No. 62) have been carried out. This compound is found to order antiferromagnetically at ~18 K (TN). The magnetization versus field isotherms obtained at 2, 3, 5, and 10 K indicate a field-induced antiferromagnetic to ferromagnetic transition in fields of the order of 0.5 T. The saturation magnetization value at 2.5 K (M extrapolated to 1/H 0) is only ~5.6uB/Tb3+, suggesting the possible presence of crystal field effects with or without a persisting antiferromagnetic component. Neutron powder diffraction data at 10 K confirm the existence of a magnetic long range order. Modeling of the magnetic scattering reveals a complex and incommensurate antiferromagnetic spin structure below TN.

  19. JOURNAL DE PHYSIQUE Colloque C5, supplment au n 5, Tome 40, Mai 1979, page C5-139 Structural instabilities in rare earth intermetallic compounds with CsCl

    E-print Network

    Paris-Sud XI, Université de

    instabilities in rare earth intermetallic compounds with CsCl structure B. Liithi and R. Sommer PhysikalischesJOURNAL DE PHYSIQUE Colloque C5, supplément au n° 5, Tome 40, Mai 1979, page C5-139 Structural.N.R.S., Grenoble Cedex, France Résumé. -- Un grand nombre de composés de terres rares métalliques et de structure

  20. Influence of nanoparticle addition on the formation and growth of intermetallic compounds (IMCs) in Cu/Sn–Ag–Cu/Cu solder joint during different thermal conditions

    NASA Astrophysics Data System (ADS)

    Tan, Ai Ting; Tan, Ai Wen; Yusof, Farazila

    2015-06-01

    Nanocomposite lead-free solders are gaining prominence as replacements for conventional lead-free solders such as Sn–Ag–Cu solder in the electronic packaging industry. They are fabricated by adding nanoparticles such as metallic and ceramic particles into conventional lead-free solder. It is reported that the addition of such nanoparticles could strengthen the solder matrix, refine the intermetallic compounds (IMCs) formed and suppress the growth of IMCs when the joint is subjected to different thermal conditions such as thermal aging and thermal cycling. In this paper, we first review the fundamental studies on the formation and growth of IMCs in lead-free solder joints. Subsequently, we discuss the effect of the addition of nanoparticles on IMC formation and their growth under several thermal conditions. Finally, an outlook on the future growth of research in the fabrication of nanocomposite solder is provided.

  1. The corrosion behavior of intermetallic compounds Ni 3(Si,Ti) and Ni 3(Si,Ti) + 2Mo in acidic solutions

    NASA Astrophysics Data System (ADS)

    Priyotomo, Gadang; Okitsu, Kenji; Iwase, Akihiro; Kaneno, Yasuyuki; Nishimura, Rokuro; Takasugi, Takayuki

    2011-07-01

    The corrosion behavior of the intermetallic compounds homogenized, Ni 3(Si,Ti) (L1 2: single phase) and Ni 3(Si,Ti) + 2Mo (L1 2 and (L1 2 + Ni ss) mixture region), has been investigated using an immersion test, electrochemical method and surface analytical method (SEM; scanning electron microscope and EPMA: electron probe microanalysis) in 0.5 kmol/m 3 H 2SO 4 and 0.5 kmol/m 3 HCl solutions at 303 K. In addition, the corrosion behavior of a solution annealed austenitic stainless steel type 304 was studied under the same experimental conditions as a reference. It was found that the intergranular attack was observed for Ni 3(Si,Ti) at an initial stage of the immersion test, but not Ni 3(Si,Ti) + 2Mo, while Ni 3(Si,Ti) + 2Mo had the preferential dissolution of L1 2 with a lower Mo concentration compared to (L1 2 + Ni ss) mixture region. From the immersion test and polarization curves, Ni 3(Si,Ti) + 2Mo showed the lowest corrosion resistance in both solutions and Ni 3(Si,Ti) had the highest corrosion resistance in the HCl solution, but not in the H 2SO 4 solution. For instance, it was found that unlike type 304 stainless steel, these intermetallic compounds were difficult to form a stable passive film in the H 2SO 4 solution. The results obtained were explained in terms of boron segregation at grain boundaries, Mo enrichment and film stability (or strength).

  2. Toughening mechanisms in intermetallics

    NASA Astrophysics Data System (ADS)

    Stoloff, N. S.

    1993-03-01

    Many intermetallic compounds offer an attractive combination of properties for either high-temperature structural applications or low-temperature corrosion resistance. Nevertheless, commercial exploitation of these compounds has been hampered by lack of adequate ductility, formability, and/or fracture toughness. In many cases, these problems are exacerbated by aggressive environments, such as oxygen or hydrogen. Methods for improving toughness in both inert and aggressive environments are discussed in this review. Techniques described include crystal structure modification, microalloying, control of grain size or shape, reinforcement by ductile fibers or particles, and control of substructure. The limitations of each of these techniques are described.

  3. Hall effect in Taylor-phase and decagonal Al 3 (Mn,Fe) complex intermetallics

    Microsoft Academic Search

    Denis StanicI; Jovica Ivkov; Ana Smontara; Zvonko Jaglicic; Janez Dolinsek; Marc Heggen; Michael Feuerbacher

    2009-01-01

    Complex metallic alloys \\/ T-phases \\/ Hall effect Abstract. The Hall coefficient (RH )o f Al 73Mn27? xFex (x ¼ 0, 2, 4 and 6) complex metallic alloys has been meas- ured in the temperature interval from 90 to 400 K. All the alloys are T (Taylor) phase except Al73Mn21Fe6 that is a decagonal (d) quasicrystal. The Hall coefficients of

  4. The influence of long range order on fatigue crack initiation in an FeCo-V intermetallic compound

    SciTech Connect

    Stoloff, N.S.; Choe, S.J.; Rajan, K. (Rensselaer Polytechnic Institute, Troy, NY (United States))

    1992-01-01

    A detailed analysis of both surface and subsurface damage accumulation in polycrystalline FeCo-2 vol pct is presented, and the observations are compared to those made on another ordered intermetallic, Ni3Al. Warm worked rods of FeCo-2-percent V were obtained from a commercial source. The alloy was annealed at 1000 C, and water quenched to produce the disordered condition. Ordering was accomplished by slow cooling to 25 C. The critical temperature for long-range order is 720 C. Cycling under strain control in air resulted in improved fatigue lives when samples were tested in the ordered condition. Cycling in a vacuum produced a small improvement in fatigue lives in both the ordered and disordered conditions. A distinct difference in cyclic hardening was noted between ordered and disordered FeCo-V. Hardening was more rapid in the ordered condition. TEM revealed that disordered material contained only unit dislocations, while ordered specimens contained superlattice dislocations. 9 refs.

  5. Spectroscopic characterization of intermetallic catalysts and correlations with methanation activity and laser mass spectrometry of organic compounds

    SciTech Connect

    Dang, T.A.

    1983-01-01

    Spectroscopic techniques such as electron spectroscopy for chemical analysis (ESCA), Auger electron spectroscopy (AES), secondary ion mass spectrometry (SIMS), ion scattering spectroscopy (ISS), scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDX) were used to characterize a number of intermetallic catalytic systems: Th/sub x/Ni/sub y/, Th/sub x/Co/sub y/ and Th Ni/sub x/Fe/sub 5-x/. The results are discussed in relation to methanation activity. Laser mass spectra (LMS) obtained for diquaternary ammonium salts do not show emission of doubly charged molecular ions. Instead, characteristic ions are formed by dehydrogenation (M-H)/sup +/ or dealkylation (M-CH/sub 3/)/sup +/ from the dication. In the case where coulombic repulsion between the two positive charges in the molecule is large, the charge separation process, M/sup 2 +/ ..-->.. M/sub 1//sup +/ + M/sub 2//sup +/, is favored over dehydrogenation and dealkylation. Emission of cluster ions occurs during laser irradiation of substituted pyridines even at threshold laser power density. The clusters generated include dimers and trimers, and appear in both positive ion and negative ion laser mass spectra.

  6. Electron diffraction study on the crystal structure of a ternary intermetallic compound Co{sub 3}AlC{sub x}

    SciTech Connect

    Mishima, Yoshinao; Hwang, K.Y.; Wei, F.G.

    1999-07-01

    Intermetallic compound Co{sub 3}AlC{sub x}, or called {kappa}-phase, has been reported to assume the E2{sub 1}, or Perovskite structure. In the present work its crystal structure is critically reinvestigated in the two-phase alloys containing {kappa}-phase in the Co primary solid solution matrix, {alpha}(Co), using conventional electron diffraction. It is shown that the crystal structure of {kappa}-phase is a derivative of E2{sub 1} being a cubic structure composed of eight E2{sub 1} sub-unit cells in a half of which the body center sites are not occupied by carbon atoms. As a result, its space group is Fm3m and the chemical formula should be Co{sub 3}AlC{sub 0.5}. It is also found that the lattice parameter of the phase is about twice as large as that of {alpha}(Co). Orientation relationship of the {kappa}-phase with the matrix {alpha}(Co) is found to be similar to the case for the {gamma}{prime} phase with the fcc {gamma} matrix in a Ni-base superalloy since three orthogonal axes of {kappa}-phase are parallel to those of {alpha}(Co). Lattice misfit under this orientation relationship between the two phases is found to be about 2.5%.

  7. Electric quadrupole and magnetic dipole interactions at 181Ta impurity in Zr2Ni7 intermetallic compound: Experiment and first-principles calculations

    NASA Astrophysics Data System (ADS)

    Dey, C. C.; Srivastava, S. K.

    2013-10-01

    Electric quadrupole interactions at 181Ta impurity in the intermetallic compound Zr2Ni7 have been studied by perturbed angular correlation technique. It has been found that there are two electric field gradients (EFG) at the 181Ta site due to two different crystalline configurations in Zr2Ni7, while contradictory results were reported from previous investigations. The values of EFG at room temperature have been found to be Vzz=7.9×1017 V/cm2 and 7.1×1017 V/cm2 corresponding to present experimental values of quadrupole frequencies and asymmetry parameters for the two sites: ?Q1=70.7(1) Mrad/s, ?=0.28(1), ?=0.8(2)% (site fraction 84%) and ?Q2=63(1) Mrad/s, ?=0.35(5), ??0 (site fraction 9%). Electric field gradients and asymmetry parameters have been computed from the complementary first-principles density functional theory (DFT) to compare with present experimental results. Our calculated values of EFG are found to be in close agreement with the experimental results. No magnetic interactions in Zr2Ni7 have been observed at 298 and 77 K which implies that there is no ferromagnetic ordering in this material down to 77 K. This observation is corroborated by theoretical calculations, wherein no magnetic moment or hyperfine field is found at any atomic site.

  8. Interfacial intermetallic compound growth and shear strength of low-silver SnAgCuBiNi/Cu lead-free solder joints

    NASA Astrophysics Data System (ADS)

    Wei, Guo-qiang; Wang, Lei; Peng, Xin-qiang; Xue, Ming-yang

    2013-09-01

    The growth rule of the interfacial intermetallic compound (IMC) and the degradation of shear strength of Sn-0.8Ag-0.5Cu-2.0Bi-0.05Ni (SACBN)/Cu solder joints were investigated in comparison with Sn-3.0Ag-0.5Cu (SAC305)/Cu solder joints aging at 373, 403, and 438 K. The results show that (Cu1- x ,Ni x )6Sn5 phase forms between the SACBN solder and Cu substrate during soldering. The interfacial IMC thickens constantly with the aging time increasing, and the higher the aging temperature, the faster the IMC layer grows. Compared with the SAC305/Cu couple, the SACBN/Cu couple exhibits a lower layer growth coefficient. The activation energies of IMC growth for SACBN/Cu and SAC305/Cu couples are 111.70 and 82.35 kJ/mol, respectively. In general, the shear strength of aged solder joints declines continuously. However, SACBN/Cu solder joints exhibit a better shear strength than SAC305/Cu solder joints.

  9. Electronic Properties of MoSi 2 Type Hf 2 X Intermetallic Compounds (X=Pd, Ag, Cd)

    Microsoft Academic Search

    I. Yaar; S. Maytal-Beck; Z. Berant

    2001-01-01

    The Hf z coordinate and the value of the electric field gradient (efg) main component (V\\u000a \\u000a zz\\u000a ), were calculated for three Hf2X compounds (X = Pd, Ag, Cd) on a first-principle basis, using the full potential linear augmented plane wave (LAPW) method.\\u000a Exchange and correlation effects were treated either by the local spine density approximation (LSDA) or by the

  10. Grain-boundary diffusion in B2 intermetallic compounds: effect of ordering on diffusion in the Fe 3Al and FeCo compounds

    Microsoft Academic Search

    Zs. Tôkei; J. Bernardini; D. L. Beke

    1999-01-01

    Grain-boundary (GB) self-diffusion in the Fe3Al and FeCo compounds was investigated in the B-kinetic regime by the radiotracer method over temperature ranges including the bulk order-disorder transition temperatures. For iron diffusion in Fe3Al the A2–B2 transition did not lead to any modification of the Arrhenius behavior, while a slight decrease of the triple product values below the B2-DO3 transition is

  11. Grain-boundary diffusion in B2 intermetallic compounds: Effect of ordering on diffusion in the Fe{sub 3}Al and FeCo compounds

    SciTech Connect

    Tokei, Z. [Univ. Aix-Marseille III (France). Lab. de Metallurgie] [Univ. Aix-Marseille III (France). Lab. de Metallurgie; [L. Kossuth Univ., Debrecen (Hungary). Dept. of Solid State Physics; Bernardini, J. [Univ. Aix-Marseille III (France). Lab. de Metallurgie] [Univ. Aix-Marseille III (France). Lab. de Metallurgie; Beke, D.L. [L. Kossuth Univ., Debrecen (Hungary). Dept. of Solid State Physics] [L. Kossuth Univ., Debrecen (Hungary). Dept. of Solid State Physics

    1999-03-10

    Grain-boundary (GB) self-diffusion in the Fe{sub 3}Al and FeCo compounds was investigated in the B-kinetic regime by the radiotracer method over temperature ranges including the bulk order-disorder transition temperatures. For iron diffusion in Fe{sub 3}Al the A2-B2 transition did not lead to any modification of the Arrhenius behavior, while a slight decrease of the triple product values below the B2-DO{sub 3} transition is observed. In FeCo both for iron and cobalt the A2-B2 transition evokes a decrease in the pre-exponential factor of the triple product, while the diffusion activation energy is not altered. These results are tentatively interpreted in view of recent segregation experiments carried out on the free surfaces of the compounds and it is proposed that owing to segregation the order-disorder transition temperature can be considerably different in GBs from that in the bulk.

  12. Complex compound polyvinyl alcohol-titanic acid/titanium dioxide

    NASA Astrophysics Data System (ADS)

    Prosanov, I. Yu.

    2013-02-01

    A complex compound polyvinyl alcohol-titanic acid has been produced and investigated by means of IR and Raman spectroscopy, X-ray diffraction, and synchronous thermal analysis. It is claimed that it represents an interpolymeric complex of polyvinyl alcohol and hydrated titanium oxide.

  13. Structure and magnetic properties of the intermetallic La2Co17-xMox (\\/x=0.5, 1, 1.5, 2) and La2Co16-yFeyMo (\\/y=0, 1, 2, 3, 4, 6) compounds

    Microsoft Academic Search

    M. Daniil; Z. M. Chen; G. C. Hadjipanayis; A. Moukarika; V. Papaefthymiou

    2001-01-01

    The effect of Mo and Fe atoms on the crystal structure and magnetic properties of the intermetallic La2Co17-xMox (\\/x=0.5, 1, 1.5, 2), and La2Co16-yFeyMo (\\/y=0, 1, 2, 3, 4, 6) compounds have been studied by X-ray diffractometry, magnetic measurements and Mössbauer spectroscopy. All samples belong to the rhombohedral Th2Zn17-type structure and their lattice parameters a and c increase both with

  14. Structure and magnetic properties of the intermetallic La 2Co 17? x Mo x ( x=0.5, 1, 1.5, 2) and La 2Co 16? y Fe y Mo ( y=0, 1, 2, 3, 4, 6) compounds

    Microsoft Academic Search

    M. Daniil; Z. M. Chen; G. C. Hadjipanayis; A. Moukarika; V. Papaefthymiou

    2001-01-01

    The effect of Mo and Fe atoms on the crystal structure and magnetic properties of the intermetallic La2Co17?xMox (x=0.5, 1, 1.5, 2), and La2Co16?yFeyMo (y=0, 1, 2, 3, 4, 6) compounds have been studied by X-ray diffractometry, magnetic measurements and Mössbauer spectroscopy. All samples belong to the rhombohedral Th2Zn17-type structure and their lattice parameters a and c increase both with

  15. High temperature aging study of intermetallic compound formation of Sn3.5Ag and Sn4.0Ag0.5Cu solders on electroless Ni (P) metallization

    Microsoft Academic Search

    Peng Sun; Cristina Andersson; Xicheng Wei; Zhaonian Cheng; Zonghe Lai; Dongkai Shangguan; Johan Liu

    2006-01-01

    The Sn-3.5Ag and Sn-4.0Ag-0.5Cu solders on electroless Ni-immersion Au metallization exhibited different interfacial morphology after high temperature storage (HTS) testing at 150degC. Ni3Sn4 intermetallic compounds (IMCs) were found in the Sn-Ag system, while in the Sn-Ag-Cu system, spalling grains of (Cu,Ni)6Sn5 IMC were observed after long aging, along with a thick (Ni,Cu)3Sn4 IMC layer which adheres to the P rich

  16. Low-Temperature Synthesis Routes to Intermetallic Superconductors

    SciTech Connect

    Schaak, Raymond E

    2008-01-08

    Over the past few years, our group has gained expertise at developing low-temperature solution-based synthetic pathways to complex nanoscale solids, with particular emphasis on nanocrystalline intermetallic compounds. Our synthetic capabilities are providing tools to reproducibly generate intermetallic nanostructures with simultaneous control over crystal structure, composition, and morphology. This DOE-funded project aims to expand these capabilities to intermetallic superconductors. This could represent an important addition to the tools that are available for the synthesis and processing of intermetallic superconductors, which traditionally utilize high-temperature, high-pressure, thin film, or gas-phase vacuum deposition methods. Our current knowledge of intermetallic superconductors suggests that significant enhancements could result from the inherent benefits of low-temperature solution synthesis, e.g. metastable phase formation, control over nanoscale morphology to facilitate size-dependent property studies, robust and inexpensive processability, low-temperature annealing and consolidation, and impurity incorporation (for doping, stoichiometry control, flux pinning, and improving the critical fields). Our focus is on understanding the superconducting properties as a function of synthetic route, crystal structure, crystallite size, and morphology, and developing the synthetic tools necessary to accomplish this. This research program can currently be divided into two classes of superconducting materials: intermetallics (transition metal/post transition metal) and metal carbides/borides. Both involve the development and exploitation of low-temperature synthesis routes followed by detailed characterization of structures and properties, with the goal of understanding how the synthetic pathways influence key superconducting properties of selected target materials. Because of the low-temperature methods used to synthesize them and the nanocrystalline morphologies of many of the products, the superconductors and their nanocrystalline precursors are potentially amenable to inexpensive and large-scale solution-based processing into wires, coatings, films, and templated or patterned structures with nanoscale and microscale features. Also, because of the new synthetic variables that play a key role in the low-temperature formation of intermetallics, the possibility exists to discover new superconductors.

  17. Contrasts in Structural and Bonding Representations among Polar Intermetallic Compounds. Strongly Differentiated Hamilton Populations for Three Related Condensed Cluster Halides of the Rare-Earth Elements

    SciTech Connect

    Gupta, Shalabh; Meyer, Gerd; Corbett, John D.

    2010-10-01

    The crystal and electronic structures of three related R{sub 3}TnX{sub 3} phases (R = rare-earth metal, Tn = transition metal, X = Cl, I) containing extended mixed-metal chains are compared and contrasted: (1) Pr{sub 3}RuI{sub 3} (P2{sub 1}/m), (2) Gd{sub 3}MnI{sub 3} (P2{sub 1}/m), and (3) Pr{sub 3}RuCl{sub 3} (Pnma). The structures all feature double chains built of pairs of condensed R{sub 6}(Tn) octahedral chains encased by halogen atoms. Pr{sub 3}RuI{sub 3} (1) lacks significant Ru-Ru bonding, evidently because of packing restrictions imposed by the large closed-shell size of iodine. However, the vertex Pr2 atoms on the chain exhibit a marked electronic differentiation. These are strongly bound to the central Ru (and to four I), but very little to four neighboring Pr in the cluster according to bond populations, in contrast to Pr2-Pr 'bond' distances that are very comparable to those elsewhere. In Gd{sub 3}MnI{sub 3} (2), the smaller metal atoms allow substantial distortions and Mn-Mn bonding. Pr{sub 3}RuCl{sub 3} (3), in contrast to the iodide (1), can be described in terms of a more tightly bound superstructure of (2) in which both substantial Ru-Ru bonding and an increased number of Pr-Cl contacts in very similar mixed-metal chains are favored by the smaller closed-shell contacts of chlorine. Local Spin Density Approximation (LSDA) Linearized Muffin-Tin Orbital (LMTO)-ASA calculations and Crystal Orbital Hamilton Population (COHP) analyses show that the customary structural descriptions in terms of condensed, Tn-stuffed, R-R bonded polyhedral frameworks are poor representations of the bonding in all. Hamilton bond populations (-ICOHP) for the polar mixed-metal R-Tn and the somewhat smaller R-X interactions account for 75-90% of the total populations in each of these phases, together with smaller contributions and variations for R-R and Tn-Tn interactions. The strength of such R-Tn contributions in polar intermetallics was first established or anticipated by Brewer. The rare-earth-metal atoms are significantly oxidized in these compounds.

  18. Contrasts in structural and bonding representations among polar intermetallic compounds. Strongly differentiated Hamilton populations for three related condensed cluster halides of the rare-earth elements.

    PubMed

    Gupta, Shalabh; Meyer, Gerd; Corbett, John D

    2010-11-01

    The crystal and electronic structures of three related R(3)TnX(3) phases (R = rare-earth metal, Tn = transition metal, X = Cl, I) containing extended mixed-metal chains are compared and contrasted: (1) Pr(3)RuI(3) (P2(1)/m), (2) Gd(3)MnI(3) (P2(1)/m), and (3) Pr(3)RuCl(3) (Pnma). The structures all feature double chains built of pairs of condensed R(6)(Tn) octahedral chains encased by halogen atoms. Pr(3)RuI(3) (1) lacks significant Ru-Ru bonding, evidently because of packing restrictions imposed by the large closed-shell size of iodine. However, the vertex Pr2 atoms on the chain exhibit a marked electronic differentiation. These are strongly bound to the central Ru (and to four I), but very little to four neighboring Pr in the cluster according to bond populations, in contrast to Pr2-Pr "bond" distances that are very comparable to those elsewhere. In Gd(3)MnI(3) (2), the smaller metal atoms allow substantial distortions and Mn-Mn bonding. Pr(3)RuCl(3) (3), in contrast to the iodide (1), can be described in terms of a more tightly bound superstructure of (2) in which both substantial Ru-Ru bonding and an increased number of Pr-Cl contacts in very similar mixed-metal chains are favored by the smaller closed-shell contacts of chlorine. Local Spin Density Approximation (LSDA) Linearized Muffin-Tin Orbital (LMTO)-ASA calculations and Crystal Orbital Hamilton Population (COHP) analyses show that the customary structural descriptions in terms of condensed, Tn-stuffed, R-R bonded polyhedral frameworks are poor representations of the bonding in all. Hamilton bond populations (-ICOHP) for the polar mixed-metal R-Tn and the somewhat smaller R-X interactions account for 75-90% of the total populations in each of these phases, together with smaller contributions and variations for R-R and Tn-Tn interactions. The strength of such R-Tn contributions in polar intermetallics was first established or anticipated by Brewer. The rare-earth-metal atoms are significantly oxidized in these compounds. PMID:20886870

  19. Nanoparticles as Reactive Precursors: Synthesis of Alloys, Intermetallic Compounds, and Multi-Metal Oxides Through Low-Temperature Annealing and Conversion Chemistry 

    E-print Network

    Bauer, John C.

    2010-07-14

    for formic acid oxidation while Pt3Sn/Vulcan XC-72 and Cu3Pt/y-Al2O3 catalyzed CO oxidiation at lower temperatures than supported Pt. Intermetallic nanoparticles of Pd were synthesized by conversion chemistry methods previously mentioned and were supported...

  20. Electronic Structure of Actinide Intermetallic Compounds: Systems with Properties varying from Paramagnetism, Itinerant Magnetism, Heavy Fermion Behaviour to 5f Localization

    Microsoft Academic Search

    Börje Johansson; Olle Eriksson; M S S Brooks; Hans L Skriver

    1986-01-01

    The electronic structure of the actinides (An) is briefly reviewed and special emphasis is given to the drastic change in 5f electron behaviour which takes place when one proceeds from the light to the hevy elements. A similar change is found for the AnRh3, intermetalic systems as a function of the actinide atomic number, although the transition seems more gradual

  1. Compound complex curves: the authentic geometry of esthetic dentistry.

    PubMed

    Scoble, Han O; White, Shane N

    2014-06-01

    Observers are drawn to the intricate and unpredictable way light reflects off the compound complex curved surfaces seen in nature, art, and industry. Teeth are no exception, containing as they do such detail in their gross anatomy, fine anatomic detail, and surface texture. Compound complex curves are particularly important when engineered materials are used to mimic naturally occurring objects, including prosthetic teeth, and they can provide both authenticity and beauty. The purpose of this article was to describe the nature of compound complex curves, their historical context, and their importance in creating natural-looking prostheses. Classically, such curves have been described by using descriptive qualitative methods or quantitative mathematical methods; now these approaches merge. Natural tooth anatomy contains interlinked features at different levels of scale from gross to fine surface texture detail. These curves should be created appropriately for individual restorative treatments. PMID:24589121

  2. Challenges in intermetallics: synthesis, structural characterization, and transitions.

    PubMed

    Macaluso, Robin T; Greve, Benjamin K

    2012-12-21

    Intermetallics that contain rare-earth elements are particularly interesting because of their temperature- and pressure-dependent structural and physical transitions that make them potential candidates for magnetic applications. This article highlights synthetic routes and structural characterization advancements used to investigate intermetallic materials. Experimental and theoretical examples of three intermetallic structure types--ThCr(2)Si(2), Heusler and Laves--are discussed to present a historical review and to illustrate the grand challenges in unravelling structure-property relationships of intermetallic compounds. PMID:22986914

  3. Rare-earth orbital contribution to the Fe Kedge x-ray magnetic circular dichroism in rare-earth transition-metal intermetallic compounds

    Microsoft Academic Search

    J. Chaboy; M. A. Laguna-Marco; M. C. Sánchez; H. Maruyama; N. Kawamura; M. Suzuki

    2004-01-01

    We present a systematic x-ray magnetic circular dichroism (XMCD) study performed at the Fe K-edge of the RFe11Ti intermetallic materials (R, rare earth). We have investigated the contribution of the rare-earth sublattice to the dichroism of the transition metal. The existence of a magnetic contribution of the rare earth has been identified and isolated from the whole spectrum. This contribution

  4. Radiation effects in FCC metals and intermetallic compounds: A molecular dynamics computer simulation study. [Cu[sub 3]Au; Ni[sub 3]Al

    SciTech Connect

    Diaz de la Rubia, T.; Guinan, M.W. (Lawrence Livermore National Lab., CA (United States)); Caro, A. (Paul Scherrer Inst. (PSI), Villigen (Switzerland))

    1992-11-16

    We review recent results on atomic mixing, radiation-induced disordering, and defect production and clustering induced by displacement cascades in Cu, Ag, Cu[sub 3]Au and Ni[sub 3]Al. We employ molecular dynamics computer simulation methods with isotropic many body potentials and recoil energies near subcascade formation regime up the locally molten cascade core in the pure metals and intermetallics. Disordering of intermetallics takes place in the cascade core, but because of the short lifetime of the displacement cascade, chemical short range order is preserved in molten zone. Results reveal very large vacancy and interstitial type defect clusters at high recoil energy and cascade energy density. Vacancies agglomerate and collapse into Frank dislocation loops in quenching of the cascade molten core. Large interstitial clusters are directly produced in cascades and form prismatic dislocation loops. Fraction of defects in clusters for low temperature cascades increases with recoil energy and approaches [approx] 70 and 60% for interstitials and vacancies, at recoil energies near threshold for subcascades. In the case of intermetallics the large energy required to produce and transport a superdislocation appears to inhibit interstitial prismatic loop punching and interstitials appear as isolated (100) dumbbells.

  5. Reduction of nitro compounds by carbon monoxide on palladium complexes

    SciTech Connect

    Min'kov A.I.; Eremenko, N.K.; Merkur'eva, S.E.; Efimov, O.A.

    1986-12-20

    Various types of nitro compounds may be reduced to the corresponding amines by carbon monoxide and water in the presence of palladium acetate and a tertiary aromatic phosphine. A catalytically active complex, (HPd/sub 2/(PPh/sub 3/)/sub 4/(CO)(HSO/sub 4/))/sub n/, was isolated.

  6. Oxidation Reduction Potential of Complex Iron Compounds in Yeast

    Microsoft Academic Search

    Thomas B. Coolidge

    1931-01-01

    WHEN an alkaline extract of yeast is saturated with ammonium sulphate there is precipitated, with the protein, cytochrome `C' and a complex iron compound giving no visible spectrum. The latter can be separated from the proteins slowly by ultra-filtration. It remains in solution when the protein, with the cytochrome `C', is precipitated by trichloracetic acid.

  7. Structural transformations in R3Cu4Sn4 (R Ho, Er, Tm) intermetallic J.M. Cadogan a, *

    E-print Network

    Ryan, Dominic

    Structural transformations in R3Cu4Sn4 (R ¼ Ho, Er, Tm) intermetallic compounds J.M. Cadogan a 2014 Available online Keywords: A. Rare-earth intermetallics B. Phase transformation B. Crystal chemistry F. Diffraction/scaterring a b s t r a c t The family of ternary intermetallic compounds R3T4X4 (R

  8. Magnetocrystalline anisotropy of rare earth intermetallics

    Microsoft Academic Search

    A. S. Ermolenko

    1976-01-01

    The peculiarities of the magnetocrystalline anisotropy of the rare earth intermetallics are discussed briefly. Only the part of the magnetic anisotropy energy related to the rare earth ion system is analyzed. This anisotropy in most cases can be satisfactorily described in terms of a single-ion model. Theory and experiment relating to magnetocrystalline anisotropy of RCo5compounds are reviewed as an example

  9. Integrating giant microwave absorption with magnetic refrigeration in one multifunctional intermetallic compound of LaFe11.6Si1.4C0.2H1.7

    PubMed Central

    Song, Ning-Ning; Ke, Ya-Jiao; Yang, Hai-Tao; Zhang, Hu; Zhang, Xiang-Qun; Shen, Bao-Gen; Cheng, Zhao-Hua

    2013-01-01

    Both microwave absorption and magnetocaloric effect (MCE) are two essential performances of magnetic materials. We observe that LaFe11.6Si1.4C0.2H1.7 intermetallic compound exhibits the advantages of both giant microwave absorption exceeding ?42?dB and magnetic entropy change of ?20?Jkg?1K?1. The excellent electromagnetic wave absorption results from the large magnetic loss and dielectric loss as well as the efficient complementarity between relative permittivity and permeability. The giant MCE effect in this material provides an ideal technique for cooling the MAMs to avoid temperature increase and infrared radiation during microwave absorption. Our finding suggests that we can integrate the giant microwave absorption with magnetic refrigeration in one multifunctional material. This integration not only advances our understanding of the correlation between microwave absorption and MCE, but also can open a new avenue to exploit microwave devices and electromagnetic stealth. PMID:23887357

  10. SrZn{sub 2}Sn{sub 2} and Ca{sub 2}Zn{sub 3}Sn{sub 6} - two new Ae-Zn-Sn polar intermetallic compounds (Ae: alkaline earth metal)

    SciTech Connect

    Stegmaier, Saskia [Department Chemie, Technische Universitaet Muenchen, Lichtenbergstrasse 4, 85747 Garching (Germany); Faessler, Thomas F., E-mail: Thomas.Faessler@lrz.tum.de [Department Chemie, Technische Universitaet Muenchen, Lichtenbergstrasse 4, 85747 Garching (Germany)

    2012-08-15

    SrZn{sub 2}Sn{sub 2} and Ca{sub 2}Zn{sub 3}Sn{sub 6}, two closely related new polar intermetallic compounds, were obtained by high temperature reactions of the elements. Their crystal structures were determined with single crystal XRD methods, and their electronic structures were analyzed by means of DFT calculations. The Zn-Sn structure part of SrZn{sub 2}Sn{sub 2} comprises (anti-)PbO-like {l_brace}ZnSn{sub 4/4}{r_brace} and {l_brace}SnZn{sub 4/4}{r_brace} layers. Ca{sub 2}Zn{sub 3}Sn{sub 6} shows similar {l_brace}ZnSn{sub 4/4}{r_brace} layers and {l_brace}Sn{sub 4}Zn{r_brace} slabs constructed of a covalently bonded Sn scaffold capped by Zn atoms. For both phases, the two types of layers are alternatingly stacked and interconnected via Zn-Sn bonds. SrZn{sub 2}Sn{sub 2} adopts the SrPd{sub 2}Bi{sub 2} structure type, and Ca{sub 2}Zn{sub 3}Sn{sub 6} is isotypic to the R{sub 2}Zn{sub 3}Ge{sub 6} compounds (R=La, Ce, Pr, Nd). Band structure calculations indicate that both SrZn{sub 2}Sn{sub 2} and Ca{sub 2}Zn{sub 3}Sn{sub 6} are metallic. Analyses of the chemical bonding with the electron localization function (ELF) show lone pair like basins at Sn atoms and Zn-Sn bonding interactions between the layers for both title phases, and covalent Sn-Sn bonding within the {l_brace}Sn{sub 4}Zn{r_brace} layers of Ca{sub 2}Zn{sub 3}Sn{sub 6}. - Graphical abstract: Crystal structures of the new Ae-Zn-Sn polar intermetallic phases SrZn{sub 2}Sn{sub 2} and Ca{sub 2}Zn{sub 3}Sn{sub 6}. Highlights: Black-Right-Pointing-Pointer New polar intermetallic phases SrZn{sub 2}Sn{sub 2} and Ca{sub 2}Zn{sub 3}Sn{sub 6}. Black-Right-Pointing-Pointer Obtained by high temperature reactions of the elements. Black-Right-Pointing-Pointer Single crystal XRD structure determination and DFT electronic structure calculations. Black-Right-Pointing-Pointer Closely related crystal and electronic structures. Black-Right-Pointing-Pointer Metallic conductivity coexisting with lone pairs and covalent bonding features.

  11. Microstructure study of the rare-earth intermetallic compounds R5(SixGe1-x)4 and R5(SixGe1-x)3

    SciTech Connect

    Cao, Qing

    2012-07-26

    The unique combination of magnetic properties and structural transitions exhibited by many members of the R{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} family (R = rare earths, 0 ? x ? 1) presents numerous opportunities for these materials in advanced energy transformation applications. Past research has proven that the crystal structure and magnetic ordering of the R{sub 5(Si{sub x}Ge{sub 1-x}){sub 4} compounds can be altered by temperature, magnetic field, pressure and the Si/Ge ratio. Results of this thesis study on the crystal structure of the Er{sub 5}Si{sub 4} compound have for the first time shown that the application of mechanical forces (i.e. shear stress introduced during the mechanical grinding) can also result in a structural transition from Gd{sub 5}Si{sub 4}-type orthorhombic to Gd{sub 5}Si{sub 2}Ge{sub 2}-type monoclinic. This structural transition is reversible, moving in the opposite direction when the material is subjected to low-temperature annealing at 500 ?C. Successful future utilization of the R{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} family in novel devices depends on a fundamental understanding of the structure-property interplay on the nanoscale level, which makes a complete understanding of the microstructure of this family especially important. Past scanning electron microscopy (SEM) observation has shown that nanometer-thin plates exist in every R{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} (“5:4”) phase studied, independent of initial parent crystal structure and composition. A comprehensive electron microscopy study including SEM, energy dispersive spectroscopy (EDS), selected area diffraction (SAD), and high resolution transmission electron microscopy (HRTEM) of a selected complex 5:4 compound based on Er rather than Gd, (Er{sub 0.9Lu{sub 0.1}){sub 5}Si{sub 4}, has produced data supporting the assumption that all the platelet-like features present in the R{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} family are hexagonal R{sub 5}(Si{sub x}Ge{sub 1-x}){sub 3} (“5:3”) phase and possess the same reported orientation relationship that exists for the Gd{sub 5}Ge{sub 4} and Gd{sub 5}Si{sub 2}Ge{sub 2} compounds, i.e. [010](102?){sub m} || [101?0](12?11){sub p}. Additionally, the phase identification in (Er{sub 0.9}Lu{sub 0.1}){sub 5}Si{sub 4} carried out using X-ray powder diffraction (XRD) techniques revealed that the low amount of 5:3 phase is undetectable in a conventional laboratory Cu K? diffractometer due to detection limitations, but that extremely low amounts of the 5:3 phase can be detected using high resolution powder diffraction (HRPD) employing a synchrotron source. These results suggest that use of synchrotron radiation for the study of R{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} compounds should be favored over conventional XRD for future investigations. The phase stability of the thin 5:3 plates in a Gd{sub 5}Ge{sub 4} sample was examined by performing long-term annealing at very high temperature. The experimental results indicate the plates are thermally unstable above 1200?C. While phase transformation of 5:3 to 5:4 occurs during the annealing, the phase transition is still fairly sluggish, being incomplete even after 24 hours annealing at this elevated temperature. Additional experiments using laser surface melting performed on the surface of a Ho{sub 5}(Si{sub 0.8}Ge{sub 0.}2){sub 4} sample showed that rapid cooling will suppress the precipitation of 5:3 plates. Bulk microstructure studies of polycrystalline and monocrystalline Gd{sub 5}Ge{sub 3} compounds examined using optical microscopy, SEM and TEM also show a series of linear features present in the Gd{sub 5}Ge{sub 3} matrix, similar in appearance in many ways to the 5:3 plates observed in R{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} compounds. A systematic microscopy analysis of these linear features revealed they also are thin plates with a stoichiometric composition of Gd{sub 5}Ge{sub 4} with an orthorhombic structure. The orientation relationship between the 5:3 matrix and the precipitate 5:4 thin plates was determined as [101?0] (12?11){s

  12. Thermal barrier coating system with intermetallic overlay bond coat

    SciTech Connect

    Duderstadt, E.C.; Nagaraj, B A.

    1993-08-24

    A superalloy article is described having a thermal barrier coating system thereon, comprising: a substrate made of a material selected from the group consisting of a nickel-based superalloy and a cobalt-based superalloy; and a thermal barrier coating system on the substrate, the thermal barrier coating system including an intermetallic bond coat overlying the substrate, the bond coat being selected from the group consisting of a nickel aluminide and a platinum aluminide intermetallic compound, a thermally grown aluminum oxide layer overlying the intermetallic bond coat, and a ceramic topcoat overlying the aluminum oxide layer.

  13. Exposure profiling of reactive compounds in complex mixtures.

    PubMed

    Goel, Shilpi; Evans-Johnson, Julie A; Georgieva, Nadia I; Boysen, Gunnar

    2013-11-16

    Humans are constantly exposed to mixtures, such as tobacco smoke, exhaust from diesel, gasoline or new bio-fuels, containing several 1000 compounds, including many known human carcinogens. Covalent binding of reactive compounds or their metabolites to DNA and formation of stable adducts is believed to be the causal link between exposure and carcinogenesis. DNA and protein adducts are well established biomarkers for the internal dose of reactive compounds or their metabolites and are an integral part of science-based risk assessment. However, technical limitations have prevented comprehensive detection of a broad spectrum of adducts simultaneously. Therefore, most studies have focused on measurement of abundant individual adducts. These studies have produced valuable insight into the metabolism of individual carcinogens, but they are insufficient for risk assessment of exposure to complex mixtures. To overcome this limitation, we present herein proof-of-principle for comprehensive exposure assessment, using N-terminal valine adduct profiles as a biomarker. The reported method is based on our previously established immunoaffinity liquid chromatography-tandem mass spectrometry (LC-MS/MS) method with modification to enrich all N-terminal valine alkylated peptides. The method was evaluated using alkylated peptide standards and globin reacted in vitro with alkylating agents (1,2-epoxy-3-butene, 1,2:3,4-diepoxybutane, propylene oxide, styrene oxide, N-ethyl-N-nitrosourea and methyl methanesulfonate), known to form N-terminal valine adducts. To demonstrate proof-of-principle, the method was successfully applied to globin from mice treated with four model compounds. The results suggest that this novel approach might be suitable for in vivo biomonitoring. PMID:23219592

  14. High-temperature structural intermetallics

    Microsoft Academic Search

    M. Yamaguchi; H. Inui; K. Ito

    2000-01-01

    In the last one and a half decades, a great deal of fundamental and developmental research has been made on high-temperature structural intermetallics aiming at the implementation of these intermetallics in aerospace, automotive and land-based applications. These intermetallics include aluminides formed with either titanium, nickel or iron and silicides formed with transition metals. Of these high-temperature intermetallics, TiAl-based alloys with

  15. Ductile ordered intermetallic alloys.

    PubMed

    Liu, C T; Stiegler, J O

    1984-11-01

    Many ordered intermetallic alloys have attractive high-temperature properties; however, low ductility and brittle fracture limit their use for structural applications. The embrittlement in these alloys is mainly caused by an insufficient number of slip systems (bulk brittleness) and poor grain-boundary cohesion. Recent studies have shown that the ductility and fabricability of ordered intermetallics can be substantially improved by alloying processes and control of microstructural features through rapid solidification and thermomechanical treatments. These results demonstrate that the brittleness problem associated with ordered intermetallics can be overcome by using physical metallurgical principles. Application of these principles will be illustrated by results on Ni(3)Al and Ni(3)V-Co(3)V-Fe(3)V. The potential for developing these alloys as a new class of high-temperature structural materials is discussed. PMID:17774926

  16. Effect of Si doping on the magnetic properties and magnetic entropy changes in the LaFe11.4Al1.6 intermetallic compound

    Microsoft Academic Search

    Q Y Dong; H W Zhang; J R Sun; B G Shen

    2008-01-01

    For NaZn13-type LaFe11.4Al1.6?xSix (x = 0–1.6) compounds, the lattice parameter linearly reduces with the increase of Si concentration. A mixture of antiferromagnetic phase and ferromagnetic clusters has been observed in the compound with x = 0.22. The magnetic phase diagram obtained from the isofield magnetization curves shows that the antiferromagnetic phase changes into the ferromagnetic phase at low temperature with

  17. Sorption of heterocyclic compounds from a complex mixture of coal-tar compounds on natural clayey till

    NASA Astrophysics Data System (ADS)

    Broholm, Mette M.; Broholm, Kim; Arvin, Erik

    1999-10-01

    The sorption and desorption of heterocyclic organic compounds in a complex multisolute system to a natural clayey till was investigated. The composition of the solutes reflect a simplified composition of an aqueous phase in contact with coal tar. Sorption was studied for two ratios (s:l) of clayey till (solid) to aqueous phase (liquid). The effect of the complex mixture of solutes on sorption of the four heterocyclic compounds: benzofuran, dibenzofuran, benzothiophene, and dibenzothiophene is evaluated by comparison with their sorption measured in single-solute systems. Sorption of the four compounds is affected by the complex mixture, with sorption decreases for all four compounds at high s:l ratio indicating competitive sorption. The effect on sorption of the individual compounds is not related to solubility or hydrophobicity of the compounds. Freundlich-type isotherms are observed for all compounds in the high s:l-ratio experiments, but for the most hydrophobic compounds isotherms are close to linear. The sorption of N-compounds and benzofuran is apparently influenced by cation exchange and dipole-dipole attraction to clay minerals. At high concentrations a dramatic increase in the sorption of the most strongly sorbing compounds is observed in the low s:l-ratio experiment. The dramatic increase in sorption appears to be a result of multimolecular layer sorption or condensation on surfaces in the clayey till at high surface density of organic compounds, and the data are fitted by BET (Brunauer, Emmet, and Teller) type 2 isotherms. The increase may or may not be induced by the presence of N-heterocyclic compounds sorbed by cation exchange and dipole-dipole attraction. The desorption of the compounds was studied for the low s:l ratio where multimolecular layer formation apparently had occurred. Partially irreversible sorption, hysteric Langmuir type desorption with isotherms of very high Kl coefficient, or behaviour reflecting dissolution of a condensed phase is observed.

  18. Weldability of intermetallic alloys

    SciTech Connect

    David, S.A. (Oak Ridge National Lab., TN (United States))

    1990-01-01

    Ordered intermetallic alloys are a unique class of material that have potential for structural applications at elevated temperatures. The paper describes the welding and weldability of these alloys. The alloys studied were nickel aluminide (Ni[sub 3]Al), titanium aluminide (Ti[sub 3]Al), and iron aluminide.

  19. CCMR: Characterization of ordered intermetallics as catalysts for fuel cell applications

    NSDL National Science Digital Library

    Cruz Quiñones, Miguel

    2005-08-17

    Characterization of new intermetallic compounds for fuel cell anodes was carried out in fuels such as formic acid (FA), methanol, and ethanol using cyclic voltammetry. A significant number of these ordered intermetallic phases exhibited enhanced electrocatalytic activity when compared to bulk platinum (Pt), in terms of both oxidation onset potential and current density. The Pt3Ta, Pt2Ta, Pt3Ti, PtZr, and Pt3Nb ordered intermetallic phases were the most promising electrocatalysts tested for fuel cell applications.

  20. New icosahedral nanoclusters in crystal structures of intermetallic compounds: Topological types of 50-atom deltahedra D50 in samson phases ?-Mg2Al3 and ?-Mg23Al30

    NASA Astrophysics Data System (ADS)

    Blatov, V. A.; Ilyushin, G. D.

    2012-12-01

    A database of intermetallic compounds has been compiled using the TOPOS program package. This database includes 514 topological types, containing 12- and 13-atom icosahedral i clusters. An isolated group of 1649 i clusters is described by 14 point groups and their maximum symmetry D 3 d (bar 3 m) and T h ( m bar 3) is established, respectively, in 47 and 25 types of crystal structures. A structural analysis of the outer quasispherical shells showed that local 63-atom i configurations 1@12@50, which contain 50 atoms in the second layer, are implemented in 8 out of 19 cases. Examples of new topologically different types of 50-atom D50 deltahedra in the Samson phases ?-Mg23Al30 and ?-Mg2Al3 are presented. Four topologically different sites with coordination numbers of 5, 6, 6, or 7 are established in the ? shell and seven sites with coordination numbers of 5, 5, 6, 6, 6, 6, or 7 are found in the ? shell. The inner i clusters for the ?-Mg2Al3 structure (with the symmetry bar 3 m) and the ?-Mg23Al30 structure (with the symmetry bar 3) have a similar chemical composition, i.e., Mg7Al6 and Mg6Al7, and their 50-atom shells are chemically identical to 18Mg + 32Al. The configurations found supplement the series of known two-layer icosahedral Bergman and Mackay clusters in the form of deltahedra with 32- and 42-atom shells.

  1. Synthesis, structures and bonding of superconducting barium vanadium sulfide and intermetallic solid state compounds of group 2, 3, 13, 14 and transition elements

    Microsoft Academic Search

    Kim Carl Lobring

    2001-01-01

    Superconducting transition is well known for the Chevrel phases M xMo6S8 and MxMo6Se 8 where M is dopant metal such as Pb, In, Tl and La. Not many ternary group 5 transition metal chalcogenides of similar composition, however, are known to be superconductors. The synthesis and observation of superconducting transition of the Ba doped compound BaxV6S8 (x = 0.45--0.48) is

  2. Effects of spin-dependent spectral weight on magnetic circular x-ray dichroism: Applications to R(NixCo1-x)5 intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Galéra, R. M.; Pizzini, S.; Blanco, J. A.; Rueff, J. P.; Fontaine, A.; Giorgetti, Ch.; Baudelet, F.; Dartyge, E.; López, M. F.

    1995-06-01

    This systematic study of R(NixCo1-x)5 compounds (R=La, Gd, and Tb) has allowed us to investigate the combined effects of the 3d-5d hybridization and 4f-5d exchange on the rare-earth L2,3-edge magnetic circular x-ray dichroism (MCXD) signal. In La compounds, where the 5d polarization results only from the magnetic transition metals via the hybridization of 5d and 3d bands, the MCXD signal scales with the 5d moment and can be explained by a one-particle model for the absorption process. When the 4f-5d exchange intervenes, like in the Gd and Tb compounds, its effects on the MCXD sign, amplitude, and the amplitude variations are very important. A description of the L2,3-edge MCXD spectra taking into account the spin-dependence of the radial matrix elements explains qualitatively the results of this study.

  3. Point defect energetics in the ZrNi and Zr2Ni intermetallics C.S. Moura a,b

    E-print Network

    Motta, Arthur T.

    The intermetallic compound ZrNi exhibits an orthorhombic B33-type structure, with lattice pa- rameters a 0:410 nmPoint defect energetics in the ZrNi and Zr2Ni intermetallics C.S. Moura a,b , A.T. Motta b , N of point defects has been conducted in the ZrNi and Zr2Ni intermetallic compounds using molecular dynamics

  4. Magnetocrystalline anisotropy of a novel Y(Fe,V) 9.66 intermetallic compound and its nitride with a disordered CaCu 5-type structure

    Microsoft Academic Search

    N. Sheloudko; M. Gjoka; O. Kalogirou; V. Psycharis; D. Niarchos; M. Mikhov

    2000-01-01

    The magnetocrystalline anisotropy of the compounds with stoichiometry Y3Fe27.5V1.5(Y(Fe,V)9.66) and Y3Fe27.5V1.5Nx(Y(Fe,V)9.66Nx) with a CaCu5-type structure has been studied by magnetization measurements in the temperature range 5–300K, analyzed by the Sucksmith–Thompson method, and by torque measurements at room temperature on powder samples oriented in a rotating magnetic field.

  5. Reactions of intermetallic clusters

    Microsoft Academic Search

    R. W. Farley; A. W. Castleman Jr.

    1990-01-01

    Reaction of bismuth--alkali clusters with closed-shell HX acids provides insight into the structures, formation, and stabilities of these intermetallic species. HC1 and HI are observed to quantitatively strip Bi{sub {ital x}}Na{sub {ital y}} and Bi{sub {ital x}}K{sub {ital y}}, respectively, of their alkali component, leaving bare bismuth clusters as the only bismuth-containing species detected. Product bismuth clusters exhibit the same

  6. Reactions of intermetallic clusters

    Microsoft Academic Search

    R. W. Farley; A. W. Castleman

    1990-01-01

    Reaction of bismuth–alkali clusters with closed-shell HX acids provides insight into the structures, formation, and stabilities of these intermetallic species. HC1 and HI are observed to quantitatively strip BixNay and BixKy, respectively, of their alkali component, leaving bare bismuth clusters as the only bismuth-containing species detected. Product bismuth clusters exhibit the same distribution observed when pure bismuth is evaporated in

  7. Intermetallics for structural applications

    Microsoft Academic Search

    V. K. Sikka; S. C. Deevi

    1995-01-01

    Intermetallics are introduced as possible structural materials. The attributes and useful temperature limits of eight of the most likely candidates have been described. In addition, detailed descriptions are given for chemical compositions, corrosion properties, mechanical properties, melting and processing, and applications of NiâAl and FeâAl-based alloys. Mechanical properties of NiâAl-based alloys are compared with commercially used HU alloys in the

  8. High-temperature structural intermetallics

    SciTech Connect

    Yamaguchi, M.; Inui, H.; Ito, K.

    2000-01-01

    In the last one and a half decades, a great deal of fundamental and developmental research has been made on high-temperature structural intermetallics aiming at the implementation of these intermetallics in aerospace, automotive and land-based applications. These intermetallics include aluminides formed with either titanium, nickel or iron and silicides formed with transition metals. Of these high-temperature intermetallics, TiAl-based alloys with great potential in both aerospace and automotive applications have been attracting particular attention. Recently TiAl turbocharger wheels have finally started being used for turbochargers for commercial passenger cars of a special type. The current status of the research and development of these high-temperature intermetallics is summarized and a perspective on what directions future research and development of high-temperature intermetallics should take is provided.

  9. Novel Hard Magnets J. F. Herbst, Chairman New rare-earth intermetallic phases 3(Fe,M)29X,,: (R=Ce, Pr, Nd, Sm, Gd;

    E-print Network

    Ryan, Dominic

    interest in the structural and magnetic properties of rare-earth (R), iron- rich intermetallic compoundsNovel Hard Magnets J. F. Herbst, Chairman New rare-earth intermetallic phases 3(Fe,M)29X,,: (R and Technology Organisatidn Lucas Heights NSW 2234, Australia New rare-earth (R), iron-rich ternary intermetallic

  10. High-Magnetic-Field XMCD as a Novel Tool for the Study of Valence Fluctuation Phenomena—Application to Eu-based Intermetallic Compounds

    Microsoft Academic Search

    Y. H. Matsuda; J. L. Her; T. Inami; K. Ohwada; Z. W. Ouyang; K. Okada; H. Nojiri; A. Mitsuda; H. Wada; N. Kawamura; M. Suzuki

    2010-01-01

    X-ray magnetic circular dichroism (XMCD) in Eu-based valence fluctuating compounds, EuNi2(Si1?x\\u000a Ge\\u000a x\\u000a )2 (x=0.82, 0.85) and EuNi2P2 are investigated at high magnetic fields up to 40 T. Distinct two XMCD peaks corresponding to different valence states, i.e.,\\u000a Eu2+ and Eu3+ states are observed in EuNi2(Si1?x\\u000a Ge\\u000a x\\u000a )2 (x=0.82) and EuNi2P2 at the L absorption edges (2p?5d). This suggests that

  11. A set of 150 pictures with morphologically complex English compound names: Norms for name agreement, familiarity,

    E-print Network

    Caramazza, Alfonso

    A set of 150 pictures with morphologically complex English compound names: Norms for name agreement Published online: 18 March 2011 # Psychonomic Society, Inc. 2011 Abstract We present a set of 150 pictures with morpho- logically complex English compound names. The pictures were collected from various sources

  12. J. Am. Chem. SOC.1993, 115, 2357-2362 2357 Metal-Metal Bonding in Engel-Brewer Intermetallics

    E-print Network

    Carter, Emily A.

    J. Am. Chem. SOC.1993, 115, 2357-2362 2357 Metal-Metal Bonding in Engel-Brewer Intermetallics cluster ZrPt,, as a representative model of Engel-Brewer compounds. Such intermetallic compounds are known geometry to be at least 101.1 kcal/mol, which supports the Engel-Brewer suggestion that an alloy of Zr

  13. Elastic anisotropy, vibrational, and thermodynamic properties of U2Ti intermetallic compound with AlB2-type structure under high pressure up to 100 GPa

    NASA Astrophysics Data System (ADS)

    Yang, Jinwen; Gao, Tao; Liu, Benqiong; Sun, Guangai; Chen, Bo

    2015-03-01

    Structural, elastic anisotropy, dynamical, and thermodynamic properties of U2Ti have been studied by employing density functional theory and density functional perturbative theory. The optimized lattice parameters a, c, unit volume V, bulk modulus B, and bond lengths dU-U, dU-Ti of U2Ti are in favorable agreement with the available experimental data and other theoretical values. The elastic constants under pressure were obtained using "energy-strain" method. The polycrystalline modulus, Poisson's ratio, brittle/ductile characteristics, Debye temperature and the integration of elastic wave velocities over different directions, and hardness under pressure are also evaluated successfully. The anisotropy of the directional bulk modulus and the Young's modulus is systematically predicted for the first time. It turns out that U2Ti should be stabilized mechanically up to 100 GPa, this compound just possesses slightly elastic anisotropy at zero pressure; however, the anisotropy becomes more and more significant with the increasing pressure. In particular, the phonon dispersion curves and phonon density of state under pressure are reported for the first time. The Raman and infrared-active phonon modes at C point are further assigned. Our results indicate that U2Ti is also stable dynamically up to 100 GPa. Additionally, within the calculated phonon density of states, the thermodynamic properties are predicted.

  14. Synthesis, structure, and bonding in K12Au21Sn4. A polar intermetallic compound with dense Au20 and open AuSn4 layers

    SciTech Connect

    Li, Bin; Kim, Sung-Jin; Miller, Gordon J.; and Corbett, John D.

    2009-10-29

    The new phase K{sub 12}Au{sub 21}Sn{sub 4} has been synthesized by direct reaction of the elements at elevated temperatures. Single crystal X-ray diffraction established its orthorhombic structure, space group Pmmn (No. 59), a = 12.162(2); b = 18.058(4); c = 8.657(2) {angstrom}, V = 1901.3(7) {angstrom}{sup 3}, and Z = 2. The structure consists of infinite puckered sheets of vertex-sharing gold tetrahedra (Au{sub 20}) that are tied together by thin layers of alternating four-bonded-Sn and -Au atoms (AuSn{sub 4}). Remarkably, the dense but electron-poorer blocks of Au tetrahedra coexist with more open and saturated Au-Sn layers, which are fragments of a zinc blende type structure that maximize tetrahedral heteroatomic bonding outside of the network of gold tetrahedra. LMTO band structure calculations reveal metallic properties and a pseudogap at 256 valence electrons per formula unit, only three electrons fewer than in the title compound and at a point at which strong Au-Sn bonding is optimized. Additionally, the tight coordination of the Au framework atoms by K plays an important bonding role: each Au tetrahedra has 10 K neighbors and each K atom has 8-12 Au contacts. The appreciably different role of the p element Sn in this structure from that in the triel members in K{sub 3}Au{sub 5}In and Rb{sub 2}Au{sub 3}Tl appears to arise from its higher electron count which leads to better p-bonding (valence electron concentrations = 1.32 versus 1.22).

  15. Recent advances in ordered intermetallics

    SciTech Connect

    Liu, C.T.

    1992-12-31

    This paper briefly summarizes recent advances in intermetallic research and development. Ordered intermetallics based on aluminides and silicides possess attractive properties for structural applications at elevated temperatures in hostile environments; however, brittle fracture and poor fracture resistance limit their use as engineering materials in many cases. In recent years, considerable efforts have been devoted to the study of the brittle fracture behavior of intermetallic alloys; as a result, both intrinsic and extrinsic factors governing brittle fracture have been identified. Recent advances in first-principles calculations and atomistic simulations further help us in understanding atomic bonding, dislocation configuration, and alloying effects in intermetallics. The basic understanding has led to the development of nickel, iron, and titanium aluminide alloys with improved mechanical and metallurgical properties for structural use. Industrial interest in ductile intermetallic alloys is high, and several examples of industrial involvement are mentioned.

  16. Structural stability of intermetallic phases in the Si–Ti system. Point defects and chemical potentials in D8 8Si 3Ti 5 phase

    Microsoft Academic Search

    Catherine Colinet; Jean-Claude Tedenac

    2010-01-01

    The total energies of intermetallic compounds in the Si–Ti system are calculated employing electronic density functional theory (DFT). The calculations are performed for the experimentally observed compounds and selected structures at their ideal stoichiometry. The calculated formation enthalpies are in good agreement with the available experimental data. For the stable intermetallic compounds, the calculated zero-temperature lattice parameters agree well with

  17. Structural considerations of intermetallic electrodes for lithium batteries

    Microsoft Academic Search

    M. M Thackeray; J. T Vaughey; C. S Johnson; A. J Kropf; R Benedek; L. M. L Fransson; K Edstrom

    2003-01-01

    Although metal alloys and intermetallic compounds have been researched extensively as possible negative electrodes for lithium batteries, only recently have efforts been made to monitor the phase transitions that occur during their reaction with lithium by in situ X-ray diffraction. These studies have lead to attempts to exploit those systems that show strong structural relationships between a parent structure and

  18. A Ring Distortion Strategy to Construct Stereochemically Complex and Structurally Diverse Compounds from Natural Products

    PubMed Central

    Huigens, Robert W.; Morrison, Karen C.; Hicklin, Robert W.; Flood, Timothy A.; Richter, Michelle F.; Hergenrother, Paul J.

    2014-01-01

    High-throughput screening is the dominant method to identify lead compounds in drug discovery. As such, the makeup of screening libraries will largely dictate the biological targets that can be modulated and the therapeutics that can be developed. Unfortunately, most compound screening collections consist principally of planar molecules with little structural or stereochemical complexity, compounds that do not offer the arrangement of chemical functionality necessary for modulation of many drug targets. Here we describe a novel, general, and facile strategy for the creation of diverse compounds with high structural and stereochemical complexity using readily available natural products as synthetic starting points. We show, through evaluation of chemical properties including fraction of sp3 carbons, ClogP, and the number of stereogenic centers, that these compounds are significantly more complex and diverse than those in standard screening collections, and guidelines are given for the application of this strategy to any suitable natural product. PMID:23422561

  19. Numerical and experimental correlation of high temperature reliability of gold wire bonding to intermetallics (Au\\/Al) uniformity

    Microsoft Academic Search

    Xueren Zhang; Tong Yan Tee

    2006-01-01

    A study of the Au\\/Al intermetallics compound (IMC) in gold wire bonds on aluminum pads is presented. A test vehicle has been deliberately built for high temperature storage (HTS) test. There are two kinds of samples, i.e., one is with uniform intermetallics in the ball bond at time zero, and another one is with non-uniform intermetallics. It is found that

  20. Delivery of complex organic compounds from evolved stars to the solar system.

    PubMed

    Kwok, Sun

    2011-12-01

    Stars in the late stages of evolution are able to synthesize complex organic compounds with aromatic and aliphatic structures over very short time scales. These compounds are ejected into the interstellar medium and distributed throughout the Galaxy. The structures of these compounds are similar to the insoluble organic matter found in meteorites. In this paper, we discuss to what extent stellar organics has enriched the primordial Solar System and possibly the early Earth. PMID:22139515

  1. English cum, a borrowed coordinator turned complex-compound marker Vincent Renner

    E-print Network

    Paris-Sud XI, Université de

    1 English cum, a borrowed coordinator turned complex-compound marker Vincent Renner Abstract This article takes issue with the traditional view of English compounds such as governess-cum- piano-teacher, according to which the medial morpheme -cum- is insignificant. The study is first centered on the appearance

  2. New crystal structure maps for intermetallic compounds

    Microsoft Academic Search

    Yoshihisa Harada; Masahiko Morinaga; Jun-ichi Saito; Yasuharu Takagi

    1997-01-01

    New crystal structure maps have been proposed on the basis of the 0953-8984\\/9\\/38\\/008\\/img6 molecular orbital calculations of electronic structures. Two electronic parameters have been introduced and employed as new parameters for the classification of crystal structures. One is the bond order and the other is the d-orbital energy level of elements. Both of them change following the position of elements

  3. Diffusion of heterocyclic compounds from a complex mixture of coal tar compounds in natural clayey till

    NASA Astrophysics Data System (ADS)

    Broholm, Mette M.; Broholm, Kim; Arvin, Erik

    1999-10-01

    The diffusion of coal-tar compounds in natural clayey till was studied experimentally. Cores were exposed to a solution with near constant concentration of coal-tar compounds in a multi-component mixture for 5 months, the cores were subsequently sub-sampled and analyzed. Diffusion profile data strongly indicates highly non-linear sorption isotherms. For dibenzofuran, dibenzothiophene, 2-methylquinoline, carbazole, phenanthrene, and fluorene, the profiles indicated significantly stronger sorption at high solute concentrations than at low solute concentrations, and than expected based on linear sorption isotherms. This corresponds with observed dramatic increase in sorption of these compounds at high surface density. For benzofuran, benzothiophene, quinoline, phenols, naphthalenes, and BTEXs the profiles indicated significantly weaker sorption at high solute concentrations than at low solute concentrations and than expected based on linear or Freundlich isotherms. The observed diffusion profiles have important implications with respect to transport of dissolved coal-tar compounds in multi-component mixtures of high concentrations as expected near immiscible phase coal-tar sources. Breakthrough times and concentration levels are affected significantly.

  4. Reaction between magnesium ammine complex compound and lithium hydride

    Microsoft Academic Search

    Masami Tsubota; Satoshi Hino; Hironobu Fujii; Chie Oomatsu; Masashi Yamana; Takayuki Ichikawa; Yoshitsugu Kojima

    2010-01-01

    The possibility of using ammonia as a hydrogen carrier is examined for the reaction between magnesium ammine complex MgCl2(NH3)6 and lithium hydride LiH. Sample was milled at low temperature of ?40 °C to avoid decomposition of MgCl2(NH3)6 during the milling. The effects of milling time, milling speed (revolutions per minute), and catalysts on hydrogen storage properties were investigated by thermogravimetry, thermal

  5. Complex magnetic behavior in the novel Kondo lattice compound CeRhSn?.

    PubMed

    Anand, V K; Adroja, D T; Hillier, A D; Kockelmann, W; Fraile, A; Strydom, A M

    2011-07-13

    We report the magnetic and transport properties of a new ternary intermetallic compound, CeRhSn?, using magnetic susceptibility, magnetization, specific heat, electrical resistivity, muon-spin relaxation (?SR) and neutron diffraction investigations. The dc magnetic susceptibility data reveal two magnetic phase transitions at 0.9 and 4 K. The overall behavior of dc susceptibility and magnetization indicates a ferrimagnetic-type phase transition near 4 K. The specific heat data also exhibit sharp ?-type anomalies at 1 and 4 K. The behavior of the specific heat anomaly under the application of a magnetic field suggests that the 1 K transition is probably related to a transition from a ferri- to a ferromagnetic state. The low temperature specific heat exhibits an enhanced Sommerfeld coefficient ? (~100 mJ mol?¹ K?²) due to the formation of a moderate heavy fermion state. The resistivity of CeRhSn? demonstrates an interplay between the RKKY and Kondo interactions which is further modified by the presence of the crystal electric field. Interestingly, the resistivity of the nonmagnetic reference compound, LaRhSn?, is found to increase with decreasing temperature. Further, the onset of long-range magnetic order below 1 K is confirmed from our ?SR study on CeRhSn?. However, the 4 K transition is not detected in the ?SR and low temperature neutron diffraction data. Analysis of the dc magnetic susceptibility data within the framework of a two-sublattice model of ferrimagnetism supports the ferrimagnetic-type transition at 4 K in CeRhSn?. We have observed an unusual frequency dependence of the peak near 4 K in the ac susceptibility, which shows that the transition temperature shifts toward the lower temperature side with increasing frequency. PMID:21673393

  6. Intermetallics for structural applications

    SciTech Connect

    Sikka, V.K.; Deevi, S.C. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1995-09-01

    Intermetallics are introduced as possible structural materials. The attributes and useful temperature limits of eight of the most likely candidates have been described. In addition, detailed descriptions are given for chemical compositions, corrosion properties, mechanical properties, melting and processing, and applications of Ni{sub 3}Al and Fe{sub 3}Al-based alloys. Mechanical properties of Ni{sub 3}Al-based alloys are compared with commercially used HU alloys in the cast condition and Haynes 214 in the wrought condition. The mechanical properties of Fe{sub 3}Al-based alloys are compared with an oxide-dispersion-strengthened (ODS) Inco alloy MA-956. Comparisons have shown that Ni{sub 3}Al-based alloys offer the best combination of oxidation and carburization resistance and are significantly stronger than the commercially used HU alloy for many of the furnace-fixture applications. However, the Fe{sub 3}Al-based alloys, which offer the best sulfidation resistance of the commercially available alloys, are significantly weaker in creep than the ODS MA-956 alloy. Even with the current strength level, Fe{sub 3}Al-based alloys are superior as porous, sintered metal filters for hot-gas cleanup in coal gasification systems. Oxide-dispersion strengthening of the Fe{sub 3}Al-based alloys is currently under way to improve their creep strength.

  7. Simultaneous complexation of organic compounds and heavy metals by a modified cyclodextrin

    SciTech Connect

    Wang, X.; Brusseau, M.L. [Univ. of Arizona, Tucson, AZ (United States)

    1995-10-01

    The cleanup of contaminated soil and groundwater at hazardous waste sites has become a major focus of research and policy debate. A major factor complicating the cleanup of many sites is the cooccurrence of organic compounds and heavy metals, the so-called mixed wastes. We investigated the ability of a modified cyclodextrin to simultaneously complex low-polarity organic compounds and heavy metals. The results of the experiments showed that carboxymethyl-{beta}-cyclodextrin could simultaneously increase the apparent aqueous solubilities of the selected organic compounds (anthracene, trichlorobenzene; biphenyl, and ODT) and complex with Cd{sup 2+}. This complexation was not significantly affected by changes in pH or by the presence of relatively high concentrations of Ca{sup 2+}. It is possible that this reagent can be used successfully to remediate hazardous waste sites contaminated by mixed wastes. 11 refs., 7 figs.

  8. CCMR: Pt hexafluoroacetlyacetonate as a Precursor for Pt Intermetallic Nanoparticle Synthesis

    NSDL National Science Digital Library

    Weiss, Marilyn

    2007-08-29

    This research sought to investigate a better precursor for platinum (Pt) intermetallic nanoparticles that can be utilized as anode electrocatalysts in fuel cells. The compound Pt hexafluoroacetylacetonate can be used as a Pt intermetallic precursor for making PtPb nanoparticles when using appropriate washes (methanol usage and hexane avoidance). Modifying the standard procedures for the synthesis of PtPb nanoparticle synthesis may be useful in future work where organic ligands must be avoided in order to achieve room temperature particle crystallization.

  9. Corrosion behaviour of an Fe 3Al-type intermetallic in a chloride containing solution

    Microsoft Academic Search

    M. C Garc??a-Alonso; M. F López; M. L Escudero; J. L González-Carrasco; D. G Morris

    1999-01-01

    The corrosion behaviour of an Fe3Al-base intermetallic compound with different crystal structures in a chloride containing solution has been investigated. The corrosion current densities of this intermetallic were independent of the material crystal structure showing a passive state stable with time. These corrosion rates were of the same order of magnitude as for 316L stainless steel. The pitting corrosion resistance

  10. Zone leveling and solution growth of complex compound semiconductors in space

    NASA Technical Reports Server (NTRS)

    Bachmann, K. J.

    1986-01-01

    A research program on complex semiconducting compounds and alloys was completed that addressed the growth of single crystals of CdSe(y)Te(1-y), Zn(x)Cd(1-x)Te, Mn(x)Cd(1-x)Te, InP(y)As(1-y) and CuInSe2 and the measurement of fundamental physico-chemical properties characterizing the above materials. The purpose of this ground based research program was to lay the foundations for further research concerning the growth of complex ternary compound semiconductors in a microgravity environment.

  11. Electron microscopy of severely deformed L12 intermetallics

    Microsoft Academic Search

    D. Geist; C. Gammer; C. Mangler; C. Rentenberger; H. P. Karnthaler

    2010-01-01

    Severe plastic deformation (SPD) can be used to make bulk, nanostructured materials. Three L12 long-range ordered (LRO) intermetallic compounds were studied by TEM methods. The superlattice glide dislocations can dissociate according to two schemes: antiphase boundary (APB) coupled unit dislocations or superlattice intrinsic stacking fault (SISF) coupled super Shockley partials; both of them are analysed by weak-beam TEM methods. The

  12. Third Intermetallic Matrix Composites Symposium, volume 350

    SciTech Connect

    Graves, J.A.; Bowman, R.R.; Lewandowski, J.J.

    1994-04-01

    Partial contents include: issues in potential IMC application for aerospace structures; powder metallurgy processing of intermetallic matrix composites; microstructure and properties of intermetallic matrix composites produced by reaction synthesis; combustion synthesis of niobium aluminide matrix composites; ambient temperature synthesis of bulk intermetallics; wear behavior of SHS intermetallic matrix composites; fracture characteristics of metal-intermetallic laminates produced by SHS reactions; and vapor phase synthesis of Ti aluminides and the interfacial bonding effect on the mechanical property of micro-composites reinforced by pyrolized SiC fibers.

  13. STUDIES ON SOME THIAZOLYLAZO COMPOUNDS AND THEIR COBALT, NICKEL, AND COPPER COMPLEXES

    Microsoft Academic Search

    M. S. Masoud; G. B. Mohamed; Y. H. Abdul-Razek; A. E. Ali; F. N. Khairy

    2002-01-01

    The thiazolylazo compounds and their Co, Ni and Cu complexes of barbituric acid, uracil, thiouracil, citrazinic acid, chromotropic acid, gallic acid, pyrogallol and salicylic acid were prepared and characterized by H NMR, IR and the effect of pH on the electronic absorption spectra. The mode of ionization, the electronic transitions and the dissociation constants were discussed. The stoichiometries of the

  14. To distinguish between complex compounds such as coffee aromas, researchers use a

    E-print Network

    Suslick, Kenneth S.

    To distinguish between complex compounds such as coffee aromas, researchers use a printed array the Coffee « All 2010 News « News « College of Liberal Arts & Sciences « University of Illinois CHEMISTRY Wake Up and Smell the Coffee Artificial nose can detect problems in coffee batches. Advertisers have

  15. Ambient volatile organic compound (VOC) concentrations around a petrochemical complex and a petroleum refinery

    Microsoft Academic Search

    Eylem Cetin; Mustafa Odabasi; Remzi Seyfioglu

    2003-01-01

    Air samples were collected between September 2000 and September 2001 in Izmir, Turkey at three sampling sites located around a petrochemical complex and an oil refinery to measure ambient volatile organic compound (VOC) concentrations. VOC concentrations were 4–20-fold higher than those measured at a suburban site in Izmir, Turkey. Ethylene dichloride, a leaded gasoline additive used in petroleum refining and

  16. High-Throughput and Rapid Screening of Low-Mass Hazardous Compounds in Complex Samples.

    PubMed

    Wang, Jing; Liu, Qian; Gao, Yan; Wang, Yawei; Guo, Liangqia; Jiang, Guibin

    2015-07-01

    Rapid screening and identification of hazardous chemicals in complex samples is of extreme importance for public safety and environmental health studies. In this work, we report a new method for high-throughput, sensitive, and rapid screening of low-mass hazardous compounds in complex media without complicated sample preparation procedures. This method is achieved based on size-selective enrichment on ordered mesoporous carbon followed by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry analysis with graphene as a matrix. The ordered mesoporous carbon CMK-8 can exclude interferences from large molecules in complex samples (e.g., human serum, urine, and environmental water samples) and efficiently enrich a wide variety of low-mass hazardous compounds. The method can work at very low concentrations down to part per trillion (ppt) levels, and it is much faster and more facile than conventional methods. It was successfully applied to rapidly screen and identify unknown toxic substances such as perfluorochemicals in human serum samples from athletes and workers. Therefore, this method not only can sensitively detect target compounds but also can identify unknown hazardous compounds in complex media. PMID:26039280

  17. Solid–Aqueous Phase Partitioning of Radionuclides by Complexing Compounds Excreted by Subsurface Bacteria

    Microsoft Academic Search

    Anna Johnsson; Johanna Arlinger; Karsten Pedersen; Arvid Ödegaard-Jensen; Yngve Albinsson

    2006-01-01

    Radionuclides are present in numerous aerobic and anaerobic subsurface environments due to nuclear weapons testing, leakage from process and storage facilities, and discharge of radioactive waste. The partitioning of radionuclides between liquid and solid phases by complexing compounds excreted by subsurface bacteria was studied. The solid–aqueous phase partitioning of pico- to submicromolar amounts of Fe, Pm, Th, and Am was

  18. Structural stability of intermetallic phases in the Sn–Ti system

    Microsoft Academic Search

    Catherine Colinet; Jean-Claude Tedenac; Suzana G. Fries

    2009-01-01

    The total energies of intermetallic compounds in the Sn–Ti system are calculated employing electronic density-functional theory (DFT) using pseudopotentials constructed by the projector augmented waves (PAW) method in the generalized gradient (GGA) approximation for the exchange and correlation energy. The calculations are performed for the experimentally observed compounds at their ideal stoichiometry as well as for structures which are stable

  19. Characterization of the crystal field interaction in rare earth intermetallics using Mössbauer spectroscopy

    Microsoft Academic Search

    G A Stewart

    2010-01-01

    Mössbauer spectroscopy is a valuable tool for the characterization of the crystal field interaction at rare earth sites in a wide range of compounds. This overview focuses on the complementary role of the 1169Tm- and 55Gd-Mössbauer resonances when investigating compounds with low magnetic ordering temperatures and highlights special issues that need to be kept in mind when working with intermetallics.

  20. Characterization of the crystal field interaction in rare earth intermetallics using Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Stewart, G. A.

    2010-03-01

    Mössbauer spectroscopy is a valuable tool for the characterization of the crystal field interaction at rare earth sites in a wide range of compounds. This overview focuses on the complementary role of the 1169Tm- and 55Gd-Mössbauer resonances when investigating compounds with low magnetic ordering temperatures and highlights special issues that need to be kept in mind when working with intermetallics.

  1. Intramolecularly Bridged Calix[4]arenes with Pronounced Complexation Ability toward Neutral Compounds.

    PubMed

    Slavík, Petr; Eigner, Václav; Lhoták, Pavel

    2015-06-01

    Regioselective derivatization via an organomercury intermediate allowed for the introduction of carboxylic acid functionality into the meta position of the calix[4]arene skeleton. Intramolecular Friedel-Crafts cyclization led to a novel type of calixarene containing a ketone bridging moiety. Subsequent attack of the ketone by organometallic compounds occurred selectively from outside providing tertiary alcohols with the OH group oriented inside the cavity. These compounds can complex neutral molecules both in the solid state (X-ray) and in solution (NMR) using the cooperative effect of hydrogen bonding (OH) and CH-? interactions from within the cavity. PMID:25974087

  2. Modeling of Substitutional Site Preference in Ordered Intermetallic Alloys

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Noebe, Ronald D.; Honecy, Frank

    1998-01-01

    We investigate the site substitution scheme of specific alloying elements in ordered compounds and the dependence of site occupancy on compound stoichiometry, alloy concentration. This basic knowledge, and the interactions with other alloying additions are necessary in order to predict and understand the effect of various alloying schemes on the physical properties of a material, its response to various temperature treatments, and the resulting mechanical properties. Many theoretical methods can provide useful but limited insight in this area, since most techniques suffer from constraints in the type of elements and the crystallographic structures that can be modeled. With this in mind, the Bozzolo-Ferrante-Smith (BFS) method for alloys was designed to overcome these limitations, with the intent of providing an useful tool for the theoretical prediction of fundamental properties and structure of complex systems. After a brief description of the BFS method, its use for the determination of site substitution schemes for individual as well as collective alloying additions to intermetallic systems is described, including results for the concentration dependence of the lattice parameter. Focusing on B2 NiAl, FeAl and CoAl alloys, the energetics of Si, Ti, V, Cr, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Hf, Ta and W alloying additions are surveyed. The effect of single additions as well as the result of two simultaneous additions, discussing the interaction between additions and their influence on site preference schemes is considered. Finally, the BFS analysis is extended to ternary L1(sub 2) (Heusler phase) alloys. A comparison between experimental and theoretical results for the limited number of cases for which experimental data is available is also included.

  3. Separating complex compound patient motion tracking data using independent component analysis

    NASA Astrophysics Data System (ADS)

    Lindsay, C.; Johnson, K.; King, M. A.

    2014-03-01

    In SPECT imaging, motion from respiration and body motion can reduce image quality by introducing motion-related artifacts. A minimally-invasive way to track patient motion is to attach external markers to the patient's body and record their location throughout the imaging study. If a patient exhibits multiple movements simultaneously, such as respiration and body-movement, each marker location data will contain a mixture of these motions. Decomposing this complex compound motion into separate simplified motions can have the benefit of applying a more robust motion correction to the specific type of motion. Most motion tracking and correction techniques target a single type of motion and either ignore compound motion or treat it as noise. Few methods account for compound motion exist, but they fail to disambiguate super-position in the compound motion (i.e. inspiration in addition to body movement in the positive anterior/posterior direction). We propose a new method for decomposing the complex compound patient motion using an unsupervised learning technique called Independent Component Analysis (ICA). Our method can automatically detect and separate different motions while preserving nuanced features of the motion without the drawbacks of previous methods. Our main contributions are the development of a method for addressing multiple compound motions, the novel use of ICA in detecting and separating mixed independent motions, and generating motion transform with 12 DOFs to account for twisting and shearing. We show that our method works with clinical datasets and can be employed to improve motion correction in single photon emission computed tomography (SPECT) images.

  4. Iron-Targeting Antitumor Activity of Gallium Compounds and Novel Insights Into Triapine®-Metal Complexes

    PubMed Central

    Antholine, William E.

    2013-01-01

    Abstract Significance: Despite advances made in the treatment of cancer, a significant number of patients succumb to this disease every year. Hence, there is a great need to develop new anticancer agents. Recent Advances: Emerging data show that malignant cells have a greater requirement for iron than normal cells do and that proteins involved in iron import, export, and storage may be altered in cancer cells. Therefore, strategies to perturb these iron-dependent steps in malignant cells hold promise for the treatment of cancer. Recent studies show that gallium compounds and metal-thiosemicarbazone complexes inhibit tumor cell growth by targeting iron homeostasis, including iron-dependent ribonucleotide reductase. Chemical similarities of gallium(III) with iron(III) enable the former to mimic the latter and interpose itself in critical iron-dependent steps in cellular proliferation. Newer gallium compounds have emerged with additional mechanisms of action. In clinical trials, the first-generation-compound gallium nitrate has exhibited activity against bladder cancer and non-Hodgkin's lymphoma, while the thiosemicarbazone Triapine® has demonstrated activity against other tumors. Critical Issues: Novel gallium compounds with greater cytotoxicity and a broader spectrum of antineoplastic activity than gallium nitrate should continue to be developed. Future Directions: The antineoplastic activity and toxicity of the existing novel gallium compounds and thiosemicarbazone-metal complexes should be tested in animal tumor models and advanced to Phase I and II clinical trials. Future research should identify biologic markers that predict tumor sensitivity to gallium compounds. This will help direct gallium-based therapy to cancer patients who are most likely to benefit from it. Antioxid. Redox Signal. 00, 000–000. PMID:22900955

  5. Efficiency of lasers utilizing vapors of complex organic compounds subjected to hard ultraviolet (266 nm) pumping

    Microsoft Academic Search

    A. P. Ermachenok; O. A. Logunov; A. V. Startsev; Iu. Iu. Stoilov

    1983-01-01

    The efficiency of stimulated emission in the range 329-400 and 500 nm by a series of complex organic compounds in gaseous mixtures with pentane (1.5 x 10 to the 21st\\/cu cm) is measured for the case where the vapor is excited by the fourth harmonic of neodymium laser radiation (266 nm, 5 nsec, 20 mJ). Lasing is observed of PPD

  6. Efficiency of lasers utilizing vapors of complex organic compounds subjected to hard ultraviolet (266 nm) pumping

    Microsoft Academic Search

    A P Ermachenok; O A Logunov; Aleksandr V Startsev; Yu Yu Sto?lov

    1983-01-01

    Measurements were made of the efficiency of stimulated emission in the range 329–400 and 500 nm by a series of complex organic compounds in gaseous mixtures with pentane (1.5×1021cm?3) when the vapor was excited by the fourth harmonic of neodymium laser radiation (266 nm, 5 nsec, 20 mJ). Lasing of PPD (340 nm) and PBD (352 nm) vapors was observed

  7. Flow injection determination of carboxylate, phosphate, and sulfhydryl compounds using metal exchange complexation.

    PubMed

    Mansour, Fotouh R; Shafi, Mohammad A; Danielson, Neil D

    2012-06-15

    The determination of carboxylate, phosphorous, and sulfhydryl compounds has been studied using flow injection by measuring the decrease in absorbance of the Fe(III)-salicylate complex due to preferential ligand interaction with ferric ion. Targeted compounds include polycarboxylates such as sodium citrate, sodium oxalate, and EDTA, anionic phosphorous compounds such as sodium monofluoroorthophosphate, sodium trimetaphosphate, and sodium hexametaphosphate, and sulfhydryl compounds such as cysteine, glutathione, and captopril. Initial flow injection optimization has focused on citrate based on its ability to replace salicylate ion in the Fe(III)-salicylate complex causing a decrease in absorbance at 525 nm proportional to the citrate concentration. Two flow injection analysis methods are developed. In the first method, offline reaction flow injection, sodium citrate dissolved in 100 ?mol L(-1) Fe-salicylate is injected in a carrier solution of 100 ?mol L(-1) Fe-salicylate. The decrease in peak area is linear over a range of 1.36-109 ?mol L(-1) using a flow rate of 1 mL min(-1) and an injection volume of 100 ?L. The effect of pH on the Fe-salicylate complex absorbance is studied from 1 to 3.5; pH 3 shows both a high and stable complex absorbance in the visible range which provided important potential selectivity over UV detection. The limit of detection is found to be less than 57 nmol L(-1) depending on the Fe(III)-salicylate concentration used. The second method is reverse flow injection using the sample as a flowing stream in which 3 mmol L(-1) Fe(III)-salicylate is injected and the decrease in the response with increased sample concentration was monitored. The commercially available pharmaceutical product (Citroma)(®) is used to assess the accuracy and precision of the two proposed methods as compared to a reference method. PMID:22748549

  8. Quantification of volatile sulfur compounds in complex gaseous matrices by solid-phase microextraction.

    PubMed

    Nielsen, Annika T; Jonsson, Susanne

    2002-07-19

    Procedures were assessed for quantifying nine volatile sulfur compounds found in complex gaseous samples collected at a biogas-production plant and a sewage treatment plant. The target compounds were extracted by solid-phase microextraction (using the 75-microm Carboxen-polydimethylsiloxane fiber coating) at 22 degrees C for 20 min, and analyzed by GC-MS. Detection limits ranged between 1 pptv (v/v) for carbon disulfide and 470 pptv (v/v) for hydrogen sulfide. High amounts of organic compounds were found during full-scan analysis of the samples and standard additions to individual sub-samples revealed that the analysis was subject to matrix effects. However, the functions obtained by standard additions were still linear and quantification was possible for all the compounds tested except hydrogen sulfide. No detectable losses were observed during storage in the sampling containers, made of Tedlar film, over a storage period of 20 h. However, water permeated through the walls and the relative humidity in the bag increased during storage until it reached the ambient level. Finally, it was shown that the drying agent, CaCl2, caused no detectable losses of any of the compounds. PMID:12188001

  9. Intermetallic-Based High-Temperature Materials

    SciTech Connect

    Sikka, V.K.

    1999-04-25

    The intermetallic-based alloys for high-temperature applications are introduced. General characteristics of intermetallics are followed by identification of nickel and iron aluminides as the most practical alloys for commercial applications. An overview of the alloy compositions, melting processes, and mechanical properties for nickel and iron aluminizes are presented. The current applications and commercial producers of nickel and iron aluminizes are given. A brief description of the future prospects of intermetallic-based alloys is also given.

  10. One-Step, Facile and Ultrafast Synthesis of Phase- and Size-Controlled Pt-Bi Intermetallic Nanocatalysts through Continuous-Flow Microfluidics.

    PubMed

    Zhang, Dongtang; Wu, Fuxiang; Peng, Manhua; Wang, Xiayan; Xia, Dingguo; Guo, Guangsheng

    2015-05-20

    Ordered intermetallic nanomaterials are of considerable interest for fuel cell applications because of their unique electronic and structural properties. The synthesis of intermetallic compounds generally requires the use of high temperatures and multiple-step processes. The development of techniques for rapid phase- and size-controlled synthesis remains a formidable challenge. The intermetallic compound Pt1Bi2 is a promising candidate catalyst for direct methanol fuel cells because of its high catalytic activity and excellent methanol tolerance. In this work, we explored a one-step, facile and ultrafast phase- and size-controlled process for synthesizing ordered Pt-Bi intermetallic nanoparticles (NPs) within seconds in microfluidic reactors. Single-phase Pt1Bi1 and Pt1Bi2 intermetallic NPs were prepared by tuning the reaction temperature, and size control was achieved by modifying the solvents and the length of the reaction channel. The as-prepared Pt-Bi intermetallic NPs exhibited excellent methanol tolerance capacity and high electrocatalytic activity. Other intermetallic nanomaterials, such as Pt3Fe intermetallic nanowires with a diameter of 8.6 nm and Pt1Sn1 intermetallic nanowires with a diameter of 6.3 nm, were also successfully synthesized using this method, thus demonstrating its feasibility and generality. PMID:25932623

  11. Determination of potentially bioaccumulating complex mixtures of organochlorine compounds in wastewater: a review.

    PubMed

    Contreras López, M Concepción

    2003-03-01

    Organic chlorine compounds can be persistent environmental contaminants and may be accumulated through the food chain to the aquatic organisms, to fish and humans, depending basically on their hydrophobic properties. Consequently, there is an interest to measure these organic compounds from both the scientific and regulatory communities. The analytical essays have been improved for measuring specific organic chlorine compounds that present the most toxicological potential (polychlorinated biphenyls [PCBs], certain pesticides and dioxins), although they are tedious and time-consuming procedures. The existing tests to measure adsorbable organic halogens (AOX) or extractable organic halogens (EOX) do not distinguish the more hydrophobic organic chlorine matter. The intention of this paper is to make a review of the existing methods to measure the potentially bioaccumulating organochlorine compounds (OCs) from wastewater and propose a methodology to a standardisation procedure for complex mixtures of OCs in wastewater, such as pulp mill effluents. A new method has been proposed for determining the most hydrophobic part of the extractable organic halogens (EOX(fob)), the lowest reported value is 0.6 microg/l, expressed as chloride, and the relative standard deviation at 20 microg/l is 7% on laboratory samples and 30% on real effluents. This new procedure could be a valuable tool to complement environmental risk assessment studies of wastewater discharges. PMID:12605924

  12. Probing Complex Free-Radical Reaction Pathways of Fuel Model Compounds

    SciTech Connect

    Buchanan III, A C [ORNL; Kidder, Michelle [ORNL; Beste, Ariana [ORNL; Britt, Phillip F [ORNL

    2012-01-01

    Fossil (e.g. coal) and renewable (e.g. woody biomass) organic energy resources have received considerable attention as possible sources of liquid transportation fuels and commodity chemicals. Knowledge of the reactivity of these complex materials has been advanced through fundamental studies of organic compounds that model constituent substructures. In particular, an improved understanding of thermochemical reaction pathways involving free-radical intermediates has arisen from detailed experimental kinetic studies and, more recently, advanced computational investigations. In this presentation, we will discuss our recent investigations of the fundamental pyrolysis pathways of model compounds that represent key substructures in the lignin component of woody biomass with a focus on molecules representative of the dominant beta-O-4 aryl ether linkages. Additional mechanistic insights gleaned from DFT calculations on the kinetics of key elementary reaction steps will also be presented, as well as a few thoughts on the significant contributions of Jim Franz to this area of free radical chemistry.

  13. Ambient volatile organic compound (VOC) concentrations around a petrochemical complex and a petroleum refinery.

    PubMed

    Cetin, Eylem; Odabasi, Mustafa; Seyfioglu, Remzi

    2003-08-01

    Air samples were collected between September 2000 and September 2001 in Izmir, Turkey at three sampling sites located around a petrochemical complex and an oil refinery to measure ambient volatile organic compound (VOC) concentrations. VOC concentrations were 4-20-fold higher than those measured at a suburban site in Izmir, Turkey. Ethylene dichloride, a leaded gasoline additive used in petroleum refining and an intermediate product of the vinyl chloride process in the petrochemical complex, was the most abundant volatile organic compound, followed by ethyl alcohol and acetone. Evaluations based on wind direction clearly indicated that ambient VOC concentrations measured were affected by the refinery and petrochemical complex emissions. VOC concentrations showed seasonal variations at all sampling sites. Concentrations were highest in summer, followed by autumn, probably due to increased evaporation of VOCs from fugitive sources as a result of higher temperatures. VOC concentrations generally increased with temperature and wind speed. Temperature and wind speed together explained 1-60% of the variability in VOC concentrations. The variability in ambient VOC concentrations that could not be explained by temperature and wind speed can be attributed to the effect of other factors (i.e. wind direction, other VOC sources). PMID:12873403

  14. Complex Organic and Inorganic Compounds in Shells of Lithium-rich K Giant Stars

    NASA Astrophysics Data System (ADS)

    de la Reza, Ramiro; Drake, Natalia A.; Oliveira, Isa; Rengaswamy, Sridharan

    2015-06-01

    Hydrocarbon organic material, as found in the interstellar medium, exists in complex mixtures of aromatic and aliphatic forms. It is considered to originate from carbon-enriched giant stars during their final stages of evolution, when very strong mass loss occurs in a few thousand years on their way to becoming planetary nebulae. We show here that the same organic compounds appear to be formed in previous stages of the evolution of giant stars, more specifically, during the first-ascending giant branch K-type stars. According to our model, this happens only when these stars are being abruptly enriched with lithium, together with the formation of a circumstellar shell with a strong mass loss during just a few thousand years. This sudden mass loss is, on average, a thousand times larger than that of normal Li-poor K giant stars. This shell would later be detached, especially when the star stops its Li enrichment and a rapid photospheric Li depletion occurs. In order to gain extra carbon-based material to form the organic hydrocarbons, as well as to explain the presence of complex inorganic compounds in these stars, we propose an interaction of these strong winds with the remaining asteroidal/cometary disks that already existed around these stars since they were dwarf A-type stars. The mechanism of interaction presented here is successful in explaining the presence of inorganic compounds however, it is unable to produce new carbon-free atoms to form the organic hydrocarbon compounds. Finally, we discuss some suggestions and speculations that can eventually help solve the long-standing puzzle of Li-rich giants.

  15. Rare-Earth Transition-Metal Intermetallics: Structure-bonding-Property Relationships

    SciTech Connect

    Mi-Kyung Han

    2006-05-01

    Our explorations of rare-earth, transition metal intermetallics have resulted in the synthesis and characterization, and electronic structure investigation, as well as understanding the structure-bonding-property relationships. Our work has presented the following results: (1) Understanding the relationship between compositions and properties in LaFe{sub 13-x}Si{sub x} system: A detailed structural and theoretical investigation provided the understanding of the role of a third element on stabilizing the structure and controlling the transformation of cubic NaZn{sub 13}-type structures to the tetragonal derivative, as well as the relationship between the structures and properties. (2) Synthesis of new ternary rare-earth iron silicides RE{sub 2-x}Fe{sub 4}Si{sub 14-y} and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi{sub 2}: This shows that the metal-semiconductor phase transition depends on the structure. The mechanism of band gap opening is described in terms of bonding and structural distortion. This result shows that the electronic structure calculations are an essential tool for understanding the relationship between structure and chemical bonding in these compounds. (4) Synthesis of new ternary rare-earth Zinc aluminides Tb{sub 3}Zn{sub 3.6}Al{sub 7.4}: Partially ordered structure of Tb{sub 3}Zn{sub 3.6}Al{sub 7.4} compound provides new insights into the formation, composition and structure of rare-earth transition-metal intermetallics. Electronic structure calculations attribute the observed composition to optimizing metal-metal bonding in the electronegative (Zn, Al) framework, while the specific ordering is strongly influenced by specific orbital interactions. (5) Synthesis of new structure type of Zn{sub 39}(Cr{sub x}Al{sub 1-x}){sub 81}: These layered structures are similar to icosahedral Mn-Al quasicrystalline compounds. Therefore, this compound may provide new insights into the formation, composition and structure of quasicrystalline materials.

  16. Rare-earth transition-metal intermetallics: Structure-bonding-property relationships

    SciTech Connect

    Han, M.K.

    2006-05-06

    The explorations of rare-earth, transition metal intermetallics have resulted in the synthesis and characterization, and electronic structure investigation, as well as understanding the structure-bonding property relationships. The work has presented the following results: (1) Understanding the relationship between compositions and properties in LaFe{sub 13-x}Si{sub x} system: A detailed structural and theoretical investigation provided the understanding of the role of a third element on stabilizing the structure and controlling the transformation of cubic NaZn{sub 13}-type structures to the tetragonal derivative, as well as the relationship between the structures and properties. (2) Synthesis of new ternary rare-earth iron silicides Re{sub 2-x}Fe{sub 4}Si{sub 14-y} and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi{sub 2}: This shows that the metal-semiconductor phase transition depends on the structure. The mechanism of band gap opening is described in terms of bonding and structural distortion. This result shows that the electronic structure calculations are an essential tool for understanding the relationship between structure and chemical bonding in these compounds. (4) Synthesis of new ternary rare-earth Zinc aluminides Tb{sub 3}Zn{sub 3.6}Al{sub 7.4}: Partially ordered structure of Tb{sub 3}Zn{sub 3.6}Al{sub 7.4} compound provides new insights into the formation, composition and structure of rare-earth transition-metal intermetallics. Electronic structure calculations attribute the observed composition to optimizing metal-metal bonding in the electronegative (Zn, Al) framework, while the specific ordering is strongly influenced by specific orbital interactions. (5) Synthesis of new structure type of Zn{sub 39}(Cr{sub x}Al{sub 1-x}){sub 81}: These layered structures are similar to icosahedral Mn-Al quasicrystalline compounds. Therefore, this compound may provide new insights into the formation, composition and structure of quasicrystalline materials.

  17. Study of the Inclusion Compound Formed between a Luminescent Europium(III) ? -Diketonate Complex and ? Cyclodextrin

    Microsoft Academic Search

    Susana S. Braga; Rute A. Sá Ferreira; Isabel S. Gonçalves; Paulo Ribeiro-Claro; Martyn Pillinger; Joäo Rocha; José J. C. Teixeira-Dias; Luís D. Carlos

    2002-01-01

    A 1 : 1 inclusion compound between ?-CD and the tris chelate complex Eu(NTA)3·2H2O [NTA = 1-(2-naphthoyl)-3,3,3-trifluoroacetone)] was prepared and characterized in the solid-state by powder X-ray diffraction, thermogravimetric analysis, FTIR, 13C CP MAS NMR and photoluminescence spectroscopy. Possible host-guest interaction geometries were generated from ab initio calculations. The photoluminescence results reveal the presence of a metal-to-ligand energy transfer that

  18. Synthesis and properties of ZnS-EuS films grown from volatile complex compounds

    SciTech Connect

    Bessergenev, V.G.; Ivanova, E.N.; Kovalevskaya, Y.A. [Siberian Branch of Russian Academy of Sciences, Novosibirsk (Russian Federation). Inst. of Inorganic Chemistry] [Siberian Branch of Russian Academy of Sciences, Novosibirsk (Russian Federation). Inst. of Inorganic Chemistry

    1997-10-01

    Deposition and characterization of films of ZnS, EuS and ZnS:Eu are described. The films have been prepared by chemical vapor deposition using new volatile complex compounds, dithiocarbamates of Zn and Eu, as precursors. Characterization includes X-ray diffraction, chemical analysis of the film composition, Raman spectroscopy, ellipsometry, and spectrophotometry. The spatial chemical homogeneity of the films has been determined using a recently developed method of differential dissolution and found to be uniform. Doping of ZnS by Eu with dopant concentration up to 0.3 at.% has been achieved. Effects of Eu doping on structural and optical properties of the films are presented.

  19. High Density Hydrogen Storage System Demonstration Using NaAlH4 Based Complex Compound Hydrides

    SciTech Connect

    Daniel A. Mosher; Xia Tang; Ronald J. Brown; Sarah Arsenault; Salvatore Saitta; Bruce L. Laube; Robert H. Dold; Donald L. Anton

    2007-07-27

    This final report describes the motivations, activities and results of the hydrogen storage independent project "High Density Hydrogen Storage System Demonstration Using NaAlH4 Based Complex Compound Hydrides" performed by the United Technologies Research Center under the Department of Energy Hydrogen Program, contract # DE-FC36-02AL67610. The objectives of the project were to identify and address the key systems technologies associated with applying complex hydride materials, particularly ones which differ from those for conventional metal hydride based storage. This involved the design, fabrication and testing of two prototype systems based on the hydrogen storage material NaAlH4. Safety testing, catalysis studies, heat exchanger optimization, reaction kinetics modeling, thermochemical finite element analysis, powder densification development and material neutralization were elements included in the effort.

  20. FIRST PRINCIPLES SIMULATION OF IRON-BASED INTERMETALLIC ALLOYS Michael Widom1

    E-print Network

    Widom, Michael

    . In a many-component alloy, phase segregation needed to grow thermodynamically stable intermetallic compounds in the supercooled liquid. Among our findings are: 1. Fe-B phase diagram (instability of interstitial effect on diffusivity. Cohesive Energy We investigate cohesive energies in the Fe1-xBx binary alloy

  1. Investigations of intermetallic alloy hydriding mechanisms. Annual progress report, May 1 1979-April 30, 1980

    SciTech Connect

    Livesay, B.R.; Larsen, J.W.

    1980-05-01

    Investigations are being conducted on mechanisms involved with the hydrogen-metal interactions which control the absorption and desorption processes in intermetallic compounds. The status of the following investigations is reported: modeling of hydride formation; microbalance investigations; microstructure investigations; flexure experiments; resistivity experiments; and nuclear backscattering measurements. These investigations concern fundamental hydrogen interaction mechanisms involved in storage alloys.

  2. Gd(3+) complexes conjugated to Pittsburgh compound B: potential MRI markers of ?-amyloid plaques.

    PubMed

    Martins, André F; Morfin, Jean-François; Geraldes, Carlos F G C; Tóth, Eva

    2014-02-01

    In an effort towards the visualization of ?-amyloid (A?) plaques by T1-weighted magnetic resonance imaging for detection of Alzheimer's disease, we report the synthesis and characterization of stable, noncharged Gd(3+) complexes of three different 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid monoamide derivatives conjugated to Pittsburgh compound B, a well-established marker of A? plaques. The ligands L1, L2, and L3 differ in the nature and size of the spacer linking the macrocyclic chelator and the Pittsburgh compound B targeting moiety, which affects their lipophilicity, the octanol-water partition coefficients of the complexes ranging from -0.15 to 0.32. Given their amphiphilic behavior, the complexes form micelles in aqueous solution (critical micellar concentration 1.00-1.49 mM). The parameters determining the relaxivity, including the water exchange rate and the rotational correlation times, were assessed for the monomeric and the micellar form by a combined (17)O NMR and (1)H nuclear magnetic relaxation dispersion (NMRD) study. They are largely influenced by the aggregation state and the hydrophobic character of the linkers. The analysis of the rotational dynamics for the aggregated state in terms of local and global motions using the Lipari-Szabo approach indicates highly flexible, large aggregates. On binding of the complexes to human serum albumin or to the amyloid peptide A?1-40 in solution, they undergo a fourfold and a twofold relaxivity increase, respectively (40 MHz). Proton relaxation enhancement studies confirmed moderate interaction of Gd(L1) and Gd(L3) with human serum albumin, with KA values ranging between 250 and 910 M(-1). PMID:24297602

  3. Structural Relationships Between Intermetallic Clathrates, Porous Tectosilicates and Clathrate Hydrates

    Microsoft Academic Search

    D. Santamaría-Pérez; F. Liebau

    \\u000a Intermetallic clathrate-type compounds, such as |Eu8|[Ga16Ge30], are Zintl phases in which a formal charge transfer from the more electropositive guest atoms (Eu) to the more electronegative\\u000a host atoms (Ga or Ge) allows the latter to form skeletons with strong directed covalent bonds (polyanions [Ga16Ge30]16?). On the other hand, in clathrasils, porous silica polymorphs, such as melanophlogite |(CH4, N2, CO2,…)8| [Si

  4. Negative thermal expansion induced by intermetallic charge transfer

    NASA Astrophysics Data System (ADS)

    Azuma, Masaki; Oka, Kengo; Nabetani, Koichiro

    2015-06-01

    Suppression of thermal expansion is of great importance for industry. Negative thermal expansion (NTE) materials which shrink on heating and expand on cooling are therefore attracting keen attention. Here we provide a brief overview of NTE induced by intermetallic charge transfer in A-site ordered double perovskites SaCu3Fe4O12 and LaCu3Fe4?xMnxO12, as well as in Bi or Ni substituted BiNiO3. The last compound shows a colossal dilatometric linear thermal expansion coefficient exceeding ?70 × 10?6 K?1 near room temperature, in the temperature range which can be controlled by substitution.

  5. Cannabis, a complex plant: different compounds and different effects on individuals

    PubMed Central

    2012-01-01

    Cannabis is a complex plant, with major compounds such as delta-9-tetrahydrocannabinol and cannabidiol, which have opposing effects. The discovery of its compounds has led to the further discovery of an important neurotransmitter system called the endocannabinoid system. This system is widely distributed in the brain and in the body, and is considered to be responsible for numerous significant functions. There has been a recent and consistent worldwide increase in cannabis potency, with increasing associated health concerns. A number of epidemiological research projects have shown links between dose-related cannabis use and an increased risk of development of an enduring psychotic illness. However, it is also known that not everyone who uses cannabis is affected adversely in the same way. What makes someone more susceptible to its negative effects is not yet known, however there are some emerging vulnerability factors, ranging from certain genes to personality characteristics. In this article we first provide an overview of the biochemical basis of cannabis research by examining the different effects of the two main compounds of the plant and the endocannabinoid system, and then go on to review available information on the possible factors explaining variation of its effects upon different individuals. PMID:23983983

  6. The chemical phenol extraction of intermetallic particles from casting AlSi5Cu1Mg alloy.

    PubMed

    Mrówka-Nowotnik, G; Sieniawski, J; Nowotnik, A

    2010-03-01

    This paper presents a chemical extraction technique for determination of intermetallic phases formed in the casting AlSi5Cu1Mg aluminium alloy. Commercial aluminium alloys contain a wide range of intermetallic particles that are formed during casting, homogenization and thermomechanical processing. During solidification, particles of intermetallics are dispersed in interdendritic spaces as fine primary phases. Coarse intermetallic compounds that are formed in this aluminium alloy are characterized by unique atomic arrangement (crystallographic structure), morphology, stability, physical and mechanical properties. The volume fraction, chemistry and morphology of the intermetallics significantly affect properties and material behaviour during thermomechanical processing. Therefore, accurate determination of intermetallics is essential to understand and control microstructural evolution in Al alloys. Thus, in this paper it is shown that chemical phenol extraction method can be applied for precise qualitative evaluation. The results of optical light microscopy LOM, scanning electron microscopy SEM and X-ray diffraction XRD analysis reveal that as-cast AlSi5Cu1Mg alloy contains a wide range of intermetallic phases such as Al(4)Fe, gamma- Al(3)FeSi, alpha-Al(8)Fe(2)Si, beta-Al(5)FeSi, Al(12)FeMnSi. PMID:20500407

  7. Molecular identification of organic compounds in atmospheric complex mixtures and relationship to atmospheric chemistry and sources.

    PubMed Central

    Mazurek, Monica A

    2002-01-01

    This article describes a chemical characterization approach for complex organic compound mixtures associated with fine atmospheric particles of diameters less than 2.5 m (PM2.5). It relates molecular- and bulk-level chemical characteristics of the complex mixture to atmospheric chemistry and to emission sources. Overall, the analytical approach describes the organic complex mixtures in terms of a chemical mass balance (CMB). Here, the complex mixture is related to a bulk elemental measurement (total carbon) and is broken down systematically into functional groups and molecular compositions. The CMB and molecular-level information can be used to understand the sources of the atmospheric fine particles through conversion of chromatographic data and by incorporation into receptor-based CMB models. Once described and quantified within a mass balance framework, the chemical profiles for aerosol organic matter can be applied to existing air quality issues. Examples include understanding health effects of PM2.5 and defining and controlling key sources of anthropogenic fine particles. Overall, the organic aerosol compositional data provide chemical information needed for effective PM2.5 management. PMID:12634131

  8. Structure Defect Property Relationships in Binary Intermetallics

    NASA Astrophysics Data System (ADS)

    Medasani, Bharat; Ding, Hong; Chen, Wei; Persson, Kristin; Canning, Andrew; Haranczyk, Maciej; Asta, Mark

    2015-03-01

    Ordered intermetallics are light weight materials with technologically useful high temperature properties such as creep resistance. Knowledge of constitutional and thermal defects is required to understand these properties. Vacancies and antisites are the dominant defects in the intermetallics and their concentrations and formation enthalpies could be computed by using first principles density functional theory and thermodynamic formalisms such as dilute solution method. Previously many properties of the intermetallics such as melting temperatures and formation enthalpies were statistically analyzed for large number of intermetallics using structure maps and data mining approaches. We undertook a similar exercise to establish the dependence of the defect properties in binary intermetallics on the underlying structural and chemical composition. For more than 200 binary intermetallics comprising of AB, AB2 and AB3 structures, we computed the concentrations and formation enthalpies of vacancies and antisites in a small range of stoichiometries deviating from ideal stoichiometry. The calculated defect properties were datamined to gain predictive capabilities of defect properties as well as to classify the intermetallics for their suitability in high-T applications. Supported by the US DOE under Contract No. DEAC02-05CH11231 under the Materials Project Center grant (Award No. EDCBEE).

  9. Method of making sintered ductile intermetallic-bonded ceramic composites

    DOEpatents

    Plucknett, K.; Tiegs, T.N.; Becher, P.F.

    1999-05-18

    A method of making an intermetallic-bonded ceramic composite involves combining a particulate brittle intermetallic precursor with a particulate reactant metal and a particulate ceramic to form a mixture and heating the mixture in a non-oxidizing atmosphere at a sufficient temperature and for a sufficient time to react the brittle intermetallic precursor and the reactant metal to form a ductile intermetallic and sinter the mixture to form a ductile intermetallic-bonded ceramic composite. 2 figs.

  10. Organic compounds as indicators for transport in an urban characterized complex karst system

    NASA Astrophysics Data System (ADS)

    Reh, R.; Licha, T.; Nödler, K.; Geyer, T.; Sauter, M.

    2012-04-01

    In northern Hesse (Germany), sediments of the Upper Permian (Zechstein-Formations) are outcropping in a coastal facies along the western rim of the Rhenish Massif. The geologic section is characterized by a sequence of carbonate rocks (carbonates of the Werra-, Staßfurt- and Leine-Formations) and predominantly fine clastic sediments. The carbonate aquifers of the Werra-Formation and the Leine-Formation are used for drinking water abstraction of a provincial town and surrounding communities. Concurrently, the urban area is characterized by industrial and commercial uses. The groundwater flow system is composed of three potential karst aquifers, aquitards and aquicludes within a complex tectonically faulted area. The study area is divided into three spring catchment areas. However, the locations of the subsurface water divides are unknown. Traditional methods to determine the catchment areas (e.g. artificial tracer tests) are difficult to apply, due to a lack of adequate injection points. The presented work deals with the use of organic compounds as indicators for subsurface flow paths. Medical drugs, pesticides, corrosion inhibitors and such typical waste water compounds as caffeine (NÖDLER ET AL. 2010) are observed in approximately fifty groundwater observation points by regular sampling. The seasonal variability of the distribution pattern of organic compounds is low. The most common compounds are atrazine and its metabolites desethylatrazine and desisopropylatrazine, as well as the corrosion inhibitor 1H-benzotriazole. Since these substances are applied in different regions different input functions can be assumed. However, the highest concentrations are detected along a North-orientated axis, which also exhibits the greatest compound variety. This distribution pattern indicates preferential flow and transport pathways in the subsurface. The absence of organic compounds in other parts of the investigation area implies the existence of a water divide between these areas. The occurence of atrazine in groundwater samples denotes the existence of a water component with a transit time of more than 20 years because the use of atrazine as a pesticide has been banned in Germany since 1991. Furthermore, since atrazine and 1H-benzotriazole are found in all investigated aquifers, the presence of hydraulic connections between the aquifers (e.g. associated to faults) is likely. In addition to the long-term flow component, the periodic detection of such antibiotics as erythromycine, after strong recharge events (for example snow-melt events), suggests also the presence of a short-term flow component in the aquifer system. Consequently, the observation of organic compounds is an appropriate method to determine subsurface flow paths within complex aquifer systems. Furthermore, such a method can also be employed in the subsurface to approximate transit times and to identify mixing zones. Lecture NÖDLER, K., LICHA, T., BESTER, B., K. SAUTER, M. (2010): Development of a multi-residue analytical method, based on liquid chromatography-tandem mass spectrometry, for the simultaneous determination of 46 micro-contaminants in aqueous samples.- Journal of Chromatography A, 1217 (2010) 6511-6521.

  11. Process for synthesizing compounds from elemental powders and product

    DOEpatents

    Rabin, Barry H. (Idaho Falls, ID); Wright, Richard N. (Idaho Falls, ID)

    1993-01-01

    A process for synthesizing intermetallic compounds from elemental powders. The elemental powders are initially combined in a ratio which approximates the stoichiometric composition of the intermetallic compound. The mixed powders are then formed into a compact which is heat treated at a controlled rate of heating such that an exothermic reaction between the elements is initiated. The heat treatment may be performed under controlled conditions ranging from a vacuum (pressureless sintering) to compression (hot pressing) to produce a desired densification of the intermetallic compound. In a preferred form of the invention, elemental powders of Fe and Al are combined to form aluminide compounds of Fe.sub.3 Al and FeAl.

  12. Spin Reorientation Phenomena in Selected Rare Earth-Transition Metal Intermetallics

    Microsoft Academic Search

    Bao-Min Ma; Baomin

    1990-01-01

    Spin reorientation phenomena in selected rare earth-transition metal intermetallic compounds have been studied in the temperature range from 20K to their T _{rm c} employing magnetic susceptibility measurements. The compounds included in this study are the RCo_5 (R = Sm, Gd, Tb, Dy, Ho and Er), Pr_2Co _{rm 17-x}Fe_ {rm x} (0 <=q x <=q 17), RTiFe_ {11}(R = Tb,

  13. New intermetallic MIrP (M=Ti, Zr, Nb, Mo) and MgRuP compounds related with MoM'P (M'=Ni and Ru) superconductor

    NASA Astrophysics Data System (ADS)

    Kito, Hijiri; Iyo, Akira; Wada, Toshimi

    2011-01-01

    Using a cubic-anvil high-pressure apparatus, ternary iridium phosphides MIrP (M=Ti, Zr, Nb, Mo) and MgRuP have been prepared by reaction of stoichiometric amounts of each metal and phosphide powders at around 2 Gpa and above 1523 K for the first time. The structure of these compounds prepared at high-pressure has been characterized by X-ray powder diffraction. Diffraction lines of these compounds are assigned by the index of the Co2Si-type structure. The electrical resistivity and the d.c magnetic susceptibility of MIrP (M=Ti, Zr, Nb, Mo) have measured at low temperatures. Unfortunately, no superconducting transition for MIrP (M=Ti, Zr, Nb, Mo) and MgRuP are observed down to 2 K.

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  15. Environmental embrittlement in ordered intermetallic alloys

    SciTech Connect

    Liu, C.T. [Oak Ridge National Lab., TN (United States); Stoloff, N.S. [Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Materials Engineering

    1992-12-31

    Ordered intermetallics based on aluminides and silicides possess many promising properties for elevated-temperature applications; however, poor fracture resistance and limited fabricability restrict their use as engineering material. Recent studies have shown that environmental embrittlement is a major cause of low ductility and brittle fracture in many ordered intermetallic alloys. There are two types of environmental embrittlement observed in intermetallic alloys. One is hydrogen-induced embrittlement occurring at ambient temperatures in air. The other is oxygen-induced embrittlement in oxidizing atmospheres at elevated temperatures. In most cases, the embrittlements are due to a dynamic effect involving generation and penetration of embrittling agents (i.e., hydrogen or oxygen ) during testing. Diffusion of embrittling agents plays a dominant role in fracture of these intermetallic alloys. This chapter summarizes recent progress in understanding and reducing environmental embrittlement in these alloys.

  16. Ion binding compounds, radionuclide complexes, methods of making radionuclide complexes, methods of extracting radionuclides, and methods of delivering radionuclides to target locations

    DOEpatents

    Chen, Xiaoyuan (Syracuse, NY); Wai, Chien M. (Moscow, ID); Fisher, Darrell R. (Richland, WA)

    2000-01-01

    The invention pertains to compounds for binding lanthanide ions and actinide ions. The invention further pertains to compounds for binding radionuclides, and to methods of making radionuclide complexes. Also, the invention pertains to methods of extracting radionuclides. Additionally, the invention pertains to methods of delivering radionuclides to target locations. In one aspect, the invention includes a compound comprising: a) a calix[n]arene group, wherein n is an integer greater than 3, the calix[n]arene group comprising an upper rim and a lower rim; b) at least one ionizable group attached to the lower rim; and c) an ion selected from the group consisting of lanthanide and actinide elements bound to the ionizable group. In another aspect, the invention includes a method of extracting a radionuclide, comprising: a) providing a sample comprising a radionuclide; b) providing a calix[n]arene compound in contact with the sample, wherein n is an integer greater than 3; and c) extracting radionuclide from the sample into the calix[n]arene compound. In yet another aspect, the invention includes a method of delivering a radionuclide to a target location, comprising: a) providing a calix[n]arene compound, wherein n is an integer greater than 3, the calix[n]arene compound comprising at least one ionizable group; b) providing a radionuclide bound to the calix[n]arene compound; and c) providing an antibody attached to the calix[n]arene compound, the antibody being specific for a material found at the target location.

  17. Neurobehavioral and sensory irritant effects of controlled exposure to a complex mixture of volatile organic compounds

    SciTech Connect

    Otto, D.; Molhave, L.; Rose, G.; Hudnell, H.K.; House, D. (Environmental Protection Agency, Research Triangle Park, NC (USA))

    1990-11-01

    Subjective reactions of discomfort, impaired air quality, irritation of mucosal membranes, and impaired memory have been reported in chemically sensitive subjects during exposure to volatile organic compounds (VOCs) found in new buildings. Sixty-six normal healthy male subjects aged 18-39 were exposed for 2.75 hr to a complex VOC mixture at 0 and 25 mg/m3. Each subject completed control and exposure sessions at one-week intervals in counterbalanced order. Measurements included comfort ratings of eye, nose and throat irritation, symptom questionnaire and computerized behavioral tests. Subjects found the odor of VOCs unpleasantly strong and reported that VOC exposure degraded air quality, increased headache and produced general discomfort. VOC exposure did not affect performance on any behavioral tests.

  18. Neurotoxic effects of controlled exposure to a complex mixture of volatile organic compounds. Final report

    SciTech Connect

    Otto, D.A.; Molhave, L.; Hudnell, H.K.; Goldstein, G.; O'Neil, J.

    1990-03-01

    Subjective reactions of discomfort, impaired air quality, irritation of mucosal membranes, and impaired memory have been reported in chemically sensitive subjects during exposure to volatile organic compounds (VOCs) found in new buildings. 66 normal healthy male subjects aged 18-39 were exposed for 2.75 hrs to a complex VOC mixture at O and 25 mg/cu m. Each subject completed control and exposure sessions at one week intervals in counterbalanced order. Measurements included comfort ratings of eye, nose and throat irritation, symptom questionnaire and computerized behavioral tests. Subjects found the odor of VOCs unpleasant and strong and reported that VOC exposure degraded air quality, increased headache and produced general discomfort. VOC exposure did not affect performance on any behavioral tests. Results indicate that subjective reactions to VOCs are not limited to chemically sensitive individuals since the study population is a subgroup that is probably least likely to be affected by chemical exposure.

  19. Innovative processing techniques for intermetallic matrix composites

    NASA Astrophysics Data System (ADS)

    Stoloff, N. S.; Alman, D. E.

    A wide range of innovative techniques for processing intermetallic matrix composites is surveyed. The majority of processes involve the use of powders, although increasing attention is being directed towards vapor phase techniques. Most intermetallic composites produced to date are reinforced by particulates or random fibers. Several techniques have been successfully employed to produce continuous fiber reinforcements. Injection molding is feasible for producing aligned short fiber reinforced composites. The major success of the various new processing techniques is improved strength (monotonic and creep).

  20. In situ examination of moving crack tips in ordered intermetallics.

    SciTech Connect

    Heuer, J.; Lam, N. Q.; Okamoto, P. R.; Stubbins, J. F.

    1999-01-25

    Recent studies have shown that high stress concentrations at moving crack tips in the intermetallic compound NiTi can induce a crystalline-to-amorphous (C-A) transformation of the crack tip region. This stress-induced C-A transformation has a temperature dependence and crystallization behavior similar to those of ion irradiation-induced C-A transformation of NiTi. The present study examines if these similarities between stress- and irradiation-induced amorphization hold true for two other intermetallic compounds, CuTi and Ni{sub 3}Ti. In situ straining was performed in an intermediate-voltage transmission electron microscope. The presence or absence of an amorphous phase was determined by dark field imaging and selected area diffraction of crack tip regions. Crack tips in both CuTi and Ni{sub 3}Ti were found to remain crystalline upon fracture. The observed absence of stress-induced amorphization in Ni{sub 3}Ti is consistent with its known absence during irradiation, but the absence in CuTi differs from its known irradiation-induced amorphization behavior. Reasons for the similarity and difference are discussed.

  1. cis-trans Germanium chains in the intermetallic compounds ALi{sub 1-x}InGe and A(Li{sub 1-x}In)Ge (A=Sr, Ba, Eu)-experimental and theoretical studies

    Microsoft Academic Search

    Tae-Soo You; Svilen Bobev

    2010-01-01

    Two types of strontium-, barium- and europium-containing germanides have been synthesized using high temperature reactions and characterized by single-crystal X-ray diffraction. All reported compounds also contain mixed-occupied Li and In atoms, resulting in quaternary phases with narrow homogeneity ranges. The first type comprises EuLi{sub 0.91(1)}In{sub 0.09}Ge, SrLi{sub 0.95(1)}In{sub 0.05}Ge and BaLi{sub 0.99(1)}In{sub 0.01}Ge, which crystallize in the orthorhombic space group

  2. Effect of Y2O3 and TiC Reinforcement Particles on Intermetallic Formation and Hardness of Al6061 Composites via Mechanical Alloying and Sintering

    NASA Astrophysics Data System (ADS)

    Chen, Chun-Liang; Lin, Chen-Han

    2015-05-01

    Al6061-based composites reinforced with 2 wt pctY2O3 and 2 wt pctTiC particles produced by mechanical alloying were investigated. The reinforced particles play important roles in the microstructural development and in determining the properties of the alloys. High-energy ball milling can facilitate a solid-state reaction between reinforced particles and the Al matrix, and the reaction kinetics of atomic diffusion can be accelerated enormously by subsequent sintering processing. As a result, complex intermetallic compounds and oxide particles can be formed in the alloy. In this study, the effect of reinforcement on phase formation and mechanical properties of Al6061-based composites has been examined. The results suggest that nano-Y2O3 particles can act as nucleation sites to facilitate formation of Al-Si-Y-O-based oxide particles. The addition of TiC particles can effectively refine the grain structure and encourage formation of iron-rich intermetallic compounds. Nanoindentation was used to understand the local variations in mechanical properties of the Al6061-based composites.

  3. Air monitoring for volatile organic compounds at the Pilot Plant Complex, Aberdeen Proving Ground, Maryland

    SciTech Connect

    Schneider, J.F.; O`Neill, H.J.; Raphaelian, L.A.; Tomczyk, N.A.; Sytsma, L.F.; Cohut, V.J.; Cobo, H.A.; O`Reilly, D.P.; Zimmerman, R.E.

    1995-03-01

    The US Army`s Aberdeen Proving Ground has been a test site for a variety of munitions, including chemical warfare agents (CWA). The Pilot Plant Complex (PPC) at Aberdeen was the site of development, manufacture, storage, and disposal of CWA. Deterioration of the buildings and violations of environmental laws led to closure of the complex in 1986. Since that time, all equipment, piping, and conduit in the buildings have been removed. The buildings have been declared free of surface CWA contamination as a result of air sampling using the military system. However, no air sampling has been done to determine if other hazardous volatile organic compounds are present in the PPC, although a wide range of toxic and/or hazardous materials other than CWA was used in the PPC. The assumption has been that the air in the PPC is not hazardous. The purpose of this air-monitoring study was to screen the indoor air in the PPC to confirm the assumption that the air does not contain volatile organic contaminants at levels that would endanger persons in the buildings. A secondary purpose was to identify any potential sources of volatile organic contaminants that need to be monitored in subsequent sampling efforts.

  4. cis-trans Germanium chains in the intermetallic compounds ALi 1– x In x Ge 2 and A 2(Li 1– x In x ) 2Ge 3 ( A=Sr, Ba, Eu)—experimental and theoreticalstudies

    Microsoft Academic Search

    Tae-Soo You; Svilen Bobev

    2010-01-01

    Two types of strontium-, barium- and europium-containing germanides have been synthesized using high temperature reactions and characterized by single-crystal X-ray diffraction. All reported compounds also contain mixed-occupied Li and In atoms, resulting in quaternary phases with narrow homogeneity ranges. The first type comprises EuLi0.91(1)In0.09Ge2, SrLi0.95(1)In0.05Ge2 and BaLi0.99(1)In0.01Ge2, which crystallize in the orthorhombic space group Pnma (BaLi0.9Mg0.1Si2 structure type, Pearson code

  5. cis-trans Germanium chains in the intermetallic compounds ALi1-xInxGe2 and A2(Li1-xInx)2Ge3 (A=Sr, Ba, Eu)experimental and theoreticalstudies

    Microsoft Academic Search

    Tae-Soo You; Svilen Bobev

    2010-01-01

    Two types of strontium-, barium- and europium-containing germanides have been synthesized using high temperature reactions and characterized by single-crystal X-ray diffraction. All reported compounds also contain mixed-occupied Li and In atoms, resulting in quaternary phases with narrow homogeneity ranges. The first type comprises EuLi0.91(1)In0.09Ge2, SrLi0.95(1)In0.05Ge2 and BaLi0.99(1)In0.01Ge2, which crystallize in the orthorhombic space group Pnma (BaLi0.9Mg0.1Si2 structure type, Pearson code

  6. Dislocation sources in ordered intermetallics

    SciTech Connect

    Yoo, M.H. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.; Appel, F.; Wagner, R. [GKSS-Research Centre, Geesthacht (Germany). Inst. for Materials Research; Mecking, H. [Technical Univ. Hamburg-Harburg, Hamburg (Germany)

    1996-09-01

    An overview on the current understanding of dislocation sources and multiplication mechanisms is made for ordered intermetallic alloys of the L1{sub 2}, B2, and D0{sub 19} structures. In L1{sub 2} alloys, a large disparity of edge/screw segments in their relative mobility reduces the efficiency of a Frank-Read Type multiplication mechanism. In Fe-40%Al of the B2 structure, a variety of dislocation sources are available for <111> slip, including ones resulting from condensation of thermal vacancies. In NiAl with the relatively high APB energy, <100> dislocations may result from the dislocation decomposition reactions, the prismatic punching out from inclusion particles, and/or steps and coated layers of the surface. Internal interfaces often provide sites for dislocation multiplication, e.g., grain boundaries, sub-boundaries in Ni{sub 3}Ga, NiAl and Ti{sub 3}Al, and antiphase domain boundaries in Ti{sub 3}Al. As for the crack tip as a dislocation source, extended SISFs trailed by super-Shockley partials emanating form the cracks in Ni{sub 3}Al and Co{sub 3}Ti are discussed in view of a possible toughening mechanism.

  7. Complexation of Amino Compounds by 18C6 Improves Selectivity by IMS-IMS-MS: Application to Petroleum Characterization

    NASA Astrophysics Data System (ADS)

    Li, Zhiyu; Valentine, Stephen J.; Clemmer, David E.

    2011-05-01

    Complexation of a series of related amino compounds by 18-crown-6 ether (18C6) is studied as a means of improving the resolution of mixtures by combinations of ion mobility spectrometry (IMS) and mass spectrometry (MS) techniques. Mixtures of the isomeric amines n-octylamine (NOA), dibutylamine (DBA), and diisopropylethylamine (DIPEA) were electrosprayed to produce gaseous [M + H]+ ions. These species have overlapping mobilities and are not resolved by IMS. Addition of 18C6 yields [M + 18C6 + H]+ ion complexes that are resolved by IMS. In subsequent experiments, [M + 18C6 + H]+ ion complexes are separated according to their mobilities and specific species are selected and exposed to collisional activation. This analysis yields dissociation voltages that are inversely correlated with the number of separate substitutions on the nitrogen atom of the amino compounds; dissociation voltages of ~40, ~90, and ~150 V are obtained for the tri-, di-, and mono-substituted amino compounds DIPEA, DBA, and NOA, respectively. For these complexes, an inverse correlation is also observed with respect to the gas-phase basicities (GB) of the amino compounds (964, 935, and 895 kJ mol-1, respectively). Studies of 18C6 complexes with a series of n-alkylamines (C n H2 n+3N where n = 3 to 18, respectively) show that dissociation voltages increase systematically (from ~140 to ~190 V) under the conditions employed. The sensitivity to collision energy provides an additional means of distinguishing between classes of compounds. The approach is extended as a means of separating nitrogen-containing compounds from petroleum.

  8. Complexation of Amino Compounds by 18C6 Improves Selectivity by IMS-IMS-MS: Application to Petroleum Characterization

    PubMed Central

    Li, Zhiyu; Valentine, Stephen J.; Clemmer, David E.

    2013-01-01

    Complexation of a series of related amino compounds by 18-crown-6 ether (18C6) is studied as a means of improving the resolution of mixtures by combinations of ion mobility spectrometry (IMS) and mass spectrometry (MS) techniques. Mixtures of the isomeric amines n-octylamine (NOA), dibutylamine (DBA), and diisopropylethylamine (DIPEA) were electrosprayed to produce gaseous [M + H]+ ions. These species have overlapping mobilities and are not resolved by IMS. Addition of 18C6 yields [M + 18C6 + H]+ ion complexes that are resolved by IMS. In subsequent experiments, [M + 18C6 + H]+ ion complexes are separated according to their mobilities and specific species are selected and exposed to collisional activation. This analysis yields dissociation voltages that are inversely correlated with the number of separate substitutions on the nitrogen atom of the amino compounds; dissociation voltages of ~40, ~90, and ~150 V are obtained for the tri-, di-, and mono-substituted amino compounds DIPEA, DBA, and NOA, respectively. For these complexes, an inverse correlation is also observed with respect to the gas-phase basicities (GB) of the amino compounds (964, 935, and 895 kJ mol?1, respectively). Studies of 18C6 complexes with a series of n-alkylamines (CnH2n+3N where n=3 to 18, respectively) show that dissociation voltages increase systematically (from ~140 to ~190 V) under the conditions employed. The sensitivity to collision energy provides an additional means of distinguishing between classes of compounds. The approach is extended as a means of separating nitrogen-containing compounds from petroleum. PMID:21472516

  9. Characterization of Complex Organic Compounds Formed in Simulated Planetary Atmospheres by the Action of High Energy Particles

    NASA Astrophysics Data System (ADS)

    Kobayashi, Kensei; Kaneko, Takeo; Saito, Takeshi

    1999-01-01

    A wide variety of organic compounds, which are not simple organics but also complex organics, have been found in planets and comets. We reported that complex organics was formed in simulated planetary atmospheres by the action of high energy particles. Here we characterized the experimental products by using chromatographic and mass spectrometric techniques. A gaseous mixture of CO, N2 and H2O was irradiated with high energy protons (major components of cosmic rays). Water-soluble non-volatile substances, which gave amino acids after acid-hydrolysis, were characterized by HPLC and mass spectrometry. Major part of the products were complex compounds with molecular weight of several hundreds. Amino acid precursors were produced even when no water was incorporated with the starting materials. It was suggested that complex molecules including amino acid precursors were formed not in solution from simple molecules like HCN, but directly in gaseous phase

  10. Effect of intermetallic phases on the anodic oxidation and corrosion of 5A06 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Li, Song-mei; Li, Ying-dong; Zhang, You; Liu, Jian-hua; Yu, Mei

    2015-02-01

    Intermetallic phases were found to influence the anodic oxidation and corrosion behavior of 5A06 aluminum alloy. Scattered intermetallic particles were examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) after pretreatment. The anodic film was investigated by transmission electron microscopy (TEM), and its corrosion resistance was analyzed by electrochemical impedance spectroscopy (EIS) and Tafel polarization in NaCl solution. The results show that the size of Al-Fe-Mg-Mn particles gradually decreases with the iron content. During anodizing, these intermetallic particles are gradually dissolved, leading to the complex porosity in the anodic film beneath the particles. After anodizing, the residual particles are mainly silicon-containing phases, which are embedded in the anodic film. Electrochemical measurements indicate that the porous anodic film layer is easily penetrated, and the barrier plays a dominant role in the overall protection. Meanwhile, self-healing behavior is observed during the long immersion time.

  11. Microstructural evolution and intermetallic formation in Al-8wt% Si-0.8wt% Fe alloy due to grain refiner and modifier additions

    NASA Astrophysics Data System (ADS)

    Hassani, Amir; Ranjbar, Khalil; Sami, Sattar

    2012-08-01

    An alloy of Al-8wt% Si-0.8wt% Fe was cast in a metallic die, and its microstructural changes due to Ti-B refiner and Sr modifier additions were studied. Apart from usual refinement and modification of the microstructure, some mutual influences of the additives took place, and no mutual poisoning effects by these additives, in combined form, were observed. It was noticed that the dimensions of the iron-rich intermetallics were influenced by the additives causing them to become larger. The needle-shaped intermetallics that were obtained from refiner addition became thicker and longer when adding the modifier. It was also found that ?-Al and eutectic silicon phases preferentially nucleate on different types of intermetallic compounds. The more iron content of the intermetallic compounds and the more changes in their dimensions occurred. Formation of the shrinkage porosities was also observed.

  12. Structural chemistry of peroxo compounds of group VI transition metals: I. Peroxo complexes of chromium (a review)

    SciTech Connect

    Sergienko, V. S. [Russian Academy of Sciences, Kurnakov Institute of General and Inorganic Chemistry (Russian Federation)], E-mail: sergienko@igic.ras.ru

    2007-07-15

    The specific features revealed in the structure of the d{sup 3} Cr(III), d{sup 2} Cr(IV), d{sup 1}Cr(V), and d{sup 0} Cr(VI) peroxo complexes with the ratios M:O{sub 2} = 1:1, 1:2, and 1:4 are considered. It is noted that, in eleven compounds of the general formula Cr(O{sub 2}){sub n}O{sub m}A{sub p} (n = 1, 2, 4; m = 0, 1; p = 0-4), the metal atoms can be in four oxidations states: +3 (d{sup 3}), +4 (d{sup 4}), +5 (d{sup 1}), and +6 (d{sup 0}). This property distinguishes chromium peroxo compounds from molybdenum and tungsten dioxygen complexes, which, with one exception, are represented by the d{sup 0}M(VI) compounds.

  13. Hydrogen-Bonded Metal-Complex Sulfonate (MCS) Inclusion Compounds: Effect of the Guest Molecule on the Host Framework

    E-print Network

    Hydrogen-Bonded Metal-Complex Sulfonate (MCS) Inclusion Compounds: Effect of the Guest Molecule as pillars. The hydrogen-bonded MCS layers and the orientations of the pillars adjust and rearrange in order-bonding needs of the guest molecules mold the soft framework into different structures. These MCS host

  14. Clinical use of an herbal-derived compound (Huperzine A) to treat putative complex partial seizures in a dog

    Microsoft Academic Search

    Barbara M. Schneider; Nicholas H. Dodman; Dominik Faissler; Niwako Ogata

    2009-01-01

    A Bernese mountain dog was diagnosed with complex partial seizures that were supported by electroencephalographic findings. Clinical signs of the problem included “star gazing,” fly snapping, licking, vacuous chewing, and ongoing anxiety. Treatment with Huperzine A, a compound isolated from Chinese club moss with NMDA receptor blocking activity, anticholinesterase activity, and anticonvulsant properties, produced useful suppression of the abnormal behavior

  15. Identification of plant compounds that disrupt the insect juvenile hormone receptor complex.

    PubMed

    Lee, Seok-Hee; Oh, Hyun-Woo; Fang, Ying; An, Saes-Byeol; Park, Doo-Sang; Song, Hyuk-Hwan; Oh, Sei-Ryang; Kim, Soo-Young; Kim, Seonghyun; Kim, Namjung; Raikhel, Alexander S; Je, Yeon Ho; Shin, Sang Woon

    2015-02-10

    Insects impact human health through vector-borne diseases and cause major economic losses by damaging crops and stored agricultural products. Insect-specific growth regulators represent attractive control agents because of their safety to the environment and humans. We identified plant compounds that serve as juvenile hormone antagonists (PJHANs). Using the yeast two-hybrid system transformed with the mosquito JH receptor as a reporter system, we demonstrate that PJHANs affect the JH receptor, methoprene-tolerant (Met), by disrupting its complex with CYCLE or FISC, formation of which is required for mediating JH action. We isolated five diterpene secondary metabolites with JH antagonist activity from two plants: Lindera erythrocarpa and Solidago serotina. They are effective in causing mortality of mosquito larvae at relatively low LD50 values. Topical application of two diterpenes caused reduction in the expression of Met target genes and retardation of follicle development in mosquito ovaries. Hence, the newly discovered PJHANs may lead to development of a new class of safe and effective pesticides. PMID:25624480

  16. Chemical speciation and equilibria of some nucleic acid compounds and their iron(III) complexes

    NASA Astrophysics Data System (ADS)

    Masoud, Mamdouh S.; Abd El-Kaway, Marwa Y.; Hindawy, Ahmed M.; Soayed, Amina A.

    The pH effect on electronic absorption spectra of some biologically active nucleic acid constituents have been studied at room temperature and the mechanism of ionization was explained. These compounds are of two categories (pyrimidines: [barbital; 5,5'-diethyl-barbituric acid], [SBA; 4,6-dihydroxy-2-mercapto-pyrimidin], [NBA; 5-nitro-2,4,6(1H,3H,5H)-pyrimidine trione] and [TU; 2,3-dihydro-2-thioxo-pyrimidin-4(1H)-one]) and (purines: [adenine; 6-amino purine], its [Schiff bases derived from adenine-acetylacetone; (Z)-4-(7H-purin-6-ylimino)pentan-2-one) and adenine-salicylaldehyde; 2-((7H-purin-6-ylimino) methyl) phenol] and its [Azo derived from adenine-resorcinol; 4-((7H-purin-6-yl)-diazenyl) benzene-1,3-diol]. The phenomena of tautomerization assigned different tautomers. Different spectrophotometric methods are applied to evaluate the pK's values that explained with their molecular structures. The interaction of Fe3+ with some selected pyrimidines (barbital, NBA and SBA) was explained using familiar six spectrophotometric methods. The data typified the existence of different absorbing species with the different stoichiometries 1:1, 1:2, 1:3 and 2:3. The stability constant of the complexes was computed. More approach was deduced to assign the existence of different species applying the distribution diagrams.

  17. Complex Organic and Inorganic Compounds in Shells of Lithium-rich K Giant Stars

    E-print Network

    de la Reza, Ramiro; Oliveira, Isa; Rengaswamy, Sridharan

    2015-01-01

    Hydrocarbon organic material, as found in the interstellar medium, exists in complex mixtures of aromatic and aliphatic forms. It is considered to be originated from carbon enriched giant stars during their final stages of evolution, when very strong mass loss occurs in a few thousand years on their way to become planetary nebulae. We show here that the same organic compounds appear to be formed in previous stages of the evolution of giant stars. More specifically, during the first ascending giant branch K-type stars. According to our model this happens only when these stars are being abruptly enriched with lithium together with the formation of a circumstellar shell with a strong mass loss during just a few thousand years. This sudden mass loss is, on an average, a thousand times larger than that of normal Li-poor K giant stars. This shell would later be detached, specially when the star stops its Li enrichment and a rapid photospheric Li depletion occurs. In order to gain extra carbon-based material to form...

  18. Personal volatile organic compound (VOC) exposure of children attending elementary schools adjacent to industrial complex

    NASA Astrophysics Data System (ADS)

    Park, Kun-Ho; Jo, Wan-Kuen

    The major deficiency in linking the effects of environmental exposure to children's health is the lack of data on the exposure of children to hazardous environmental pollutants. Accordingly, the present study compared the personal volatile organic compound (VOC) exposure of children from four elementary schools at different proximities to the Daegu Dyeing Industrial Complex (DDIC) and adjacent to different traffic densities. The personal air concentrations of four VOCs (toluene, m, p-xylenes, and o-xylene) were significantly higher for the children attending the school (S1) closest to the boundary of the DDIC compared to the children attending the school (S2) further away. The DDIC was the likely primary cause for the elevated personal air concentrations of the four VOCs in the children attending the school nearest the DDIC. The personal exposure to toluene and methyl tertiary-butyl ether (MTBE) for the children attending the school near a major roadway with a high traffic density was significantly higher than that for the children attending the school near a roadway with a low traffic density. The difference in the breath concentrations was generally similar to the difference in the personal air concentrations among the children from the four schools. In contrast to the children attending schools in low-income areas, the children attending schools in high-income areas exhibited no significant difference in the concentrations of any of the target VOCs in the personal air and breath samples between the children living with and without a smoker in the home.

  19. Study of bulk ground state properties of cerium intermetallics by linear dichroism in 4f resonant inelastic X-ray scattering

    E-print Network

    Marcon, Marco

    Study of bulk ground state properties of cerium intermetallics by linear dichroism in 4f resonant resonant inelastic X-ray scattering in the M5 region of intermetallic compounds of cerium (CeRh2, CePd3, Ce: 71.20.Lp; 71.27. 1 a; 71.28. 1 d; 78.70.ck Keywords: C. X-ray scattering; C. Crystal structure

  20. Structure and thermal stability of complexes of chromium, manganese, cobalt, and copper with nonhydrocarbon macromolecular compounds of petroleum

    SciTech Connect

    Paukku, A.N.; Posadov, I.A.; Rozental, D.A.; Gusev, V.P.; Sirotinkin, N.V.; Lozarev, S.Y.

    1982-11-10

    The structure and thermolysis parameters of complexes formed by Cr(III), Mn(II), Co(II), and Cu(II) with petroleum NHMC was studied. The following series of metal ions was chosen for evaluation of the influence of their electronic configuraton on the stability of the complexes formed: Cr/sup 3 +/(d/sup 3/), Mn/sup 2 +/(d/sup 5/), Co/sup 2 +/(d/sup 7/) and Cu/sup 2 +/(d/sup 9/). The complex compounds were synthesized from hydrated forms of the metal acetates in a salt of petroleum NHMC concentrates with rapid stirring at 70/sup 0/, at 50:1 molar ratio of ligand to metal acetate. Unreacted petroleum NHMC were removed from the complex compounds by extraction with n-hexane in a Soxhlet apparatus. The IR spectra of the petroleum NHMC concentrates and their complex compounds in KBr tablets were recorded in the region of 4000-400 cm/sup -1/ with the aid of the UR-20 spectrometer.

  1. PdGa intermetallic hydrogenation catalyst: an NMR and physical property study.

    PubMed

    Klanjšek, M; Gradišek, A; Kocjan, A; Bobnar, M; Jegli?, P; Wencka, M; Jagli?i?, Z; Pop?evi?, P; Ivkov, J; Smontara, A; Gille, P; Armbrüster, M; Grin, Yu; Dolinšek, J

    2012-02-29

    The PdGa intermetallic compound is a highly selective and stable heterogeneous hydrogenation catalyst for the semi-hydrogenation of acetylene. We have studied single crystals of PdGa grown by the Czochralski technique. The (69)Ga electric-field-gradient (EFG) tensor was determined by means of NMR spectroscopy, giving experimental confirmation of both the recently refined structural model of PdGa and the theoretically predicted Pd-Ga covalent bonding scheme. The hydrogenation experiment has detected no hydrogen uptake in the PdGa, thus preventing in situ hydride formation that leads to a reduction of the catalytic selectivity. We have also determined bulk physical properties (the magnetic susceptibility, the electrical resistivity, the thermoelectric power, the Hall coefficient, the thermal conductivity and the specific heat) of single-crystalline PdGa. The results show that PdGa is a diamagnet with metallic electrical resistivity and moderately high thermal conductivity. The thermoelectric power is negative with complicated temperature dependence, whereas the Hall coefficient is positive and temperature-dependent, indicating complexity of the Fermi surface. Partial fulfillment of the NMR Korringa relation reveals that the charge carriers are weakly correlated. Specific heat measurements show that the density of electronic states (DOS) at the Fermi energy of PdGa is reduced to 15% of the DOS of the elemental Pd metal. PMID:22310701

  2. Heterometallic compounds with the binuclear complex anion [Cr 2 (OH)(Ac)(Nta) 2 ] 2? : Synthesis and structure

    Microsoft Academic Search

    V. Ciornea; S. Shova; Gh. Novitchi; D. Ganzhu; O. N. Kazheva; A. Gulea; Yu. A. Simonov

    2009-01-01

    Heterometallic compounds BaCr2(OH)(Ac)(Nta)2 · 4H2O (I) and [Fe(L)3][Cr2(OH)(Ac)(Nta)2] · nH2O (L is Bipy (II) and Phen (III); Bipy is, ???-bipyridine, Phen is o,o?-phenanthroline, Ac? is acetate ion, Nta is nitrilotriacetate ion; n = 8 (II) and 6.25 (III)) are synthesized. According to the X-ray diffraction data, compounds II and III have ionic structures built of the isolated complex cations [Fe(L)3]2+,

  3. Heat Affected Zone and inter-metallic's formation in gold wire thermosonic bonding as function of wire material

    Microsoft Academic Search

    Jeromerajan Premkumar; Maasi Gopinath; Meng Yong Shie; Gary-TS Tay

    2011-01-01

    The paper is focused on the Heat Affected Zone (HAZ) and Inter-Metallic Compound (IMC) formation in gold wire bonding using different dopants in gold wire material. The HAZ is studied as a function of different current in the free air ball settings. It has been identified that high Ca dopant containing gold wire significantly leads to less inter metallization reaction

  4. Calculation of lattice defects in structural intermetallics by first-principles tight binding approach

    Microsoft Academic Search

    K. Masuda-Jindo

    1995-01-01

    An electronic theory for the total energy of transition-metal-polyvalent-metal binary alloys is developed using the generalized recursion method and the local-density-functional theory. This approach allows us to calculate the formation energy and the atomic structure of various lattice defects (point defects, planar defects, grain boundary and dislocations) in the intermetallic compounds like Ni3Al, NiAl and TiAl. The fundamental properties of

  5. Synthesis of NiTi intermetallics by self-propagating combustion

    Microsoft Academic Search

    C. L Yeh; W. Y Sung

    2004-01-01

    The production of NiTi intermetallic compounds from elemental powder compacts was conducted by self-propagating high-temperature synthesis (SHS) in this study. Effects of initial sample density, preheating temperature, and Ni particle size on the combustion characteristics, as well as on the final composition and morphology of products were studied. For the samples with densities between 50 and 60% theoretical maximum density

  6. Point defect concentrations and hardening in binary B2 intermetallics

    SciTech Connect

    Pike, L.M.; Chang, Y.A. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Materials Science and Engineering] [Univ. of Wisconsin, Madison, WI (United States). Dept. of Materials Science and Engineering; Liu, C.T. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.] [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1997-09-01

    Point defect hardening in binary B2 intermetallic compounds with the anti-structure defect structure (FeCo and AuZn) and the triple defect structure (NiAl, FeAl, and CoAl) was investigated. Thermodynamic modeling combined with experimental measurements of lattice parameters and bulk densities were used to establish point defect concentrations as functions of composition and temperature. Microhardness measurements were made on samples of varying compositions and quenching temperatures. Solution hardening rates of vacancies were found to be significantly larger than those of anti-site defects. It was possible to relate the hardening rates of anti-site defects to the magnitude of the lattice dilation. This suggests that the elastic size effect was the primary hardening mechanism. No such correlation was found for vacancies.

  7. DNA Cleavage, Cytotoxic Activities, and Antimicrobial Studies of Ternary Copper(II) Complexes of Isoxazole Schiff Base and Heterocyclic Compounds

    PubMed Central

    Chityala, Vijay Kumar; Sathish Kumar, K.; Macha, Ramesh; Tigulla, Parthasarathy; Shivaraj

    2014-01-01

    Novel mixed ligand bivalent copper complexes [Cu. L. A. ClO4] and [Cu. L. A] where “L” is Schiff bases, namely 2-((3,4-dimethylisoxazol-5-ylimino)methyl)-4-bromophenol (DMIIMBP)/2-((3,4-dimethylisoxazol-5-ylimino)methyl)-4-chlorophenol (DMIIMCP), and “A” is heterocyclic compound, such as 1,10-phenanthroline (phen)/2,21-bipyridyl (bipy)/8-hydroxyquinoline (oxine)/5-chloro-8-hydroxyquinoline (5-Cl-oxine), have been synthesized. These complexes have been characterized by IR, UV-Vis, ESR, elemental analysis, magnetic moments, TG, and DTA. On the basis of spectral studies and analytical data, five-coordinated square pyramidal/four-coordinated square planar geometry is assigned to all complexes. The ligands and their ternary complexes with Cu(II) have been screened for antimicrobial activity against bacteria and fungi by paper disc method. The antimicrobial studies of Schiff bases and their metal complexes showed significant activity and further it is observed that the metal complexes showed more activity than corresponding Schiff bases. In vitro antitumor activity of Cu(II) complexes was assayed against human cervical carcinoma (HeLa) cancer cells and it was observed that few complexes exhibit good antitumor activity on HeLa cell lines. The DNA cleavage studies have also been carried out on pBR 322 and it is observed that these Cu(II) complexes are capable of cleaving supercoiled plasmid DNA in the presence of H2O2 and UV light. PMID:24895493

  8. Slater-Pauling behavior within quaternary intermetallic borides of the Ti{sub 3}Co{sub 5}B{sub 2} structure-type

    SciTech Connect

    Burghaus, Jens [Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52062 Aachen (Germany); Dronskowski, Richard, E-mail: drons@HAL9000.ac.rwth-aachen.d [Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52062 Aachen (Germany); Miller, Gordon J. [Department of Chemistry, Iowa State University, Ames, IA 50011 (United States)

    2009-10-15

    First-principles, density-functional studies of several intermetallic borides of the general type M{sub 2}M'Ru{sub 5-n}Rh{sub n}B{sub 2} (n=0-5; M=Sc, Ti, Nb; M'=Fe, Co) show that the variation in saturation magnetic moment with valence-electron count follows a Slater-Pauling curve, with a maximum moment occurring typically at 66 valence electrons. The magnetic moments in these compounds occur primarily from the 3d electrons of the magnetically active M' sites, with some contribution from the Ru/Rh sites via magnetic polarization. Electronic DOS curves reveal that a rigid-band approach is a reasonable approximation for the estimation of saturation moments and the analysis of orbital interactions in this family of complex borides. COHP analyses of the M'-M' orbital interactions indicate optimized interactions in the minority spin states for Co-containing phases, but strong bonding interactions remaining in Fe-containing phases. - Graphical abstract: Theoretically determined (spin-polarized LMTO-GGA) local magnetic moments as a function of the chemical valence Z for various intermetallic borides.

  9. Quaternary borocarbides: New class of intermetallic superconductors

    NASA Technical Reports Server (NTRS)

    Nagarajan, R.; Gupta, L. C.; Dhar, S. K.; Mazumdar, Chandan; Hossain, Zakir; Godart, C.; Levy-Clement, C.; Padalia, B. D.; Vijayaraghavan, R.

    1995-01-01

    Our recent discovery of superconductivity (SC) in the four-element multiphase Y-Ni-B-C system at an elevated temperature (TC approximately 12 K) has opened up great possibilities of identifying new superconducting materials and generating new physics. Superconductivity with Tc (greater than 20 K) higher than that known so far in bulk intermetallics has been observed in multiphase Y-Pd-B-C and Th-Pd-B-C systems and a family of single phase materials RENi2B2C (RE= Y, rare earth) have been found. Our investigations show YNi2B2C to be a strong coupling hard type-II SC. HC2(T) exhibits an unconventional temperature dependence. Specific heat and magnetization studies reveal coexistence of SC and magnetism in RNi2B2C (R = Ho, Er, Tm) with magnetic ordering temperatures (Tc approximately 8 K, 10.5 K, 11 K and Tm approximately 5 K, approximately 7K, approximately 4 K respectively) that are remarkably higher than those in known magnetic superconductors . Mu-SR studies suggest the possibility of Ni atoms carrying a moment in TmNi2B2C. Resistivity results suggests a double re-entrant transition (SC-normal-SC) in HoNi2B2C. RENi2B2C (RE = Ce, Nd, Gd) do not show SC down to 4.2 K. The Nd- and Gd-compounds order magnetically at approximately 4.5 K and approximately 19.5 K, respectively. Two SC transitions are observed in Y-Pd-B-C (Tc approximately 22 K, approximately 10 K) and in Th-Pd-B-C (Tc approximately 20 K, approximately 14 K) systems, which indicate that there are at least two structures which support SC in these borocarbides. In our multiphase ThNi2B2C we observe SC at approximately 6 K. No SC was seen in multiphase UNi2B2C, UPd2B2C, UOs2Ge2C and UPd5B3C(0.35) down to 4.2 K. Tc in YNi2B2C is depressed by substitutions (Gd, Th and U at Y-sites and Fe, Co at Ni-sites).

  10. Intelligent processing of intermetallic composite consolidation

    Microsoft Academic Search

    H. N. G. Wadley; D. M. Elzey; L. M. Hsiung; Y. Lu; J. M. Duva

    1990-01-01

    Intermetallic composites based upon titanium aluminide matrices and silicon carbide of aluminum oxide fibers are emerging candidates for future hypersonic vehicle airframes and engines. To tailor the properties of these 'engineered' materials for specific application, to increase process yield, and to reduce costs, 'intelligent processing of materials' (IPM) control strategies are being explored for their processing. Recent progress is evaluated

  11. Surfaces of Intermetallics: Quasicrystals and Beyond

    SciTech Connect

    Yuen, Chad [Ames Laboratory

    2012-10-26

    The goal of this work is to characterize surfaces of intermetallics, including quasicrystals. In this work, surface characterization is primarily focused on composition and structure using X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM) performed under ultrahigh vacuum (UHV) conditions.

  12. Dislocation core structure in ordered intermetallic alloys

    Microsoft Academic Search

    R. Pasianot; D. Farkas; E. J. Savino

    1991-01-01

    The basic features of dislocation core structures in ordered intermetallic alloys are discussed, as revealed by atomistic computer simulation. The simulated dislocation core structures are for the most commonly observed slip systems in both L12 and B2 alloys. The simulations were carried out with embedded atom interatomic potentials. Screw and edge dislocations were studied, particularly investigating the planarity of the

  13. BRIEF COMMUNICATIONS: Efficiency of lasers utilizing vapors of complex organic compounds subjected to hard ultraviolet (266 nm) pumping

    Microsoft Academic Search

    A. P. Ermachenok; O. A. Logunov; Aleksandr V. Startsev; Yu Yu Stoilov

    1983-01-01

    Measurements were made of the efficiency of stimulated emission in the range 329-400 and 500 nm by a series of complex organic compounds in gaseous mixtures with pentane (1.5×1021cm-3) when the vapor was excited by the fourth harmonic of neodymium laser radiation (266 nm, 5 nsec, 20 mJ). Lasing of PPD (340 nm) and PBD (352 nm) vapors was observed

  14. Reactive processing of nickel-aluminide intermetallic compounds

    Microsoft Academic Search

    H. X. Zhu; R. Abbaschian

    2003-01-01

    NiAl have been fabricated by reactive sintering compacts of ball-milled powder mixtures containing Ni and Al. The reaction mechanism, as well as phase and microstructural development, were investigated by analyzing compacts quenched from different temperatures during reactive hot compaction. It was found that the reaction process was strongly affected by pressure, heating rates, heat loss from the sample to the

  15. Unusual low temperature specific heat in ternary Gd intermetallic compounds

    Microsoft Academic Search

    M. J. Parsons; J. Crangle; K.-U. Neumann; K. R. A. Ziebeck

    1998-01-01

    Specific heat measurements are reported for the alloy series Pd2GdxLa1-x In for 0<=x<=1.0, and also for Pd2LuIn and Cu2GdIn. A well defined anomaly associated with the onset of the magnetically ordered state is observed in the specific heat for Pd2GdIn at T=9 K. As x decreases the anomaly becomes broader and the maximum reduces to a lower temperature. Measurements on

  16. Unusual low temperature specific heat in ternary Gd intermetallic compounds

    Microsoft Academic Search

    M. J Parsons; J Crangle; K.-U Neumann; K. R. A Ziebeck

    1998-01-01

    Specific heat measurements are reported for the alloy series Pd2GdxLa1?x In for 0?x?1.0, and also for Pd2LuIn and Cu2GdIn. A well defined anomaly associated with the onset of the magnetically ordered state is observed in the specific heat for Pd2GdIn at T=9K. As x decreases the anomaly becomes broader and the maximum reduces to a lower temperature. Measurements on the

  17. Addressing Machining Issues for the Intermetallic Compound 60-NITINOL

    NASA Technical Reports Server (NTRS)

    Stanford, Malcolm K.; Wozniak, Walter A.; McCue, Terry R.

    2012-01-01

    60-NITINOL (60 wt.% Ni - 40 wt.% Ti) is being studied as a material for advanced aerospace components. Frequent wire breakage during electrical-discharge machining of this material was investigated. The studied material was fabricated from hot isostatically pressed 60-NITINOL powder obtained through a commercial source. Bulk chemical analysis of the material showed that the composition was nominal but had relatively high levels of certain impurities, including Al and O. It was later determined that Al2O3 particles had contaminated the material during the hot isostatic pressing procedure and that these particles were the most likely cause of the wire breakage. The results of this investigation highlight the importance of material cleanliness to its further implementation.

  18. Magnetic Structure of the Intermetallic Compound MnHg

    Microsoft Academic Search

    Yasuaki Nakagawa; Hiroshi Watanabe; Tomiei Hori

    1964-01-01

    The antiferromagetic structure of MnHg was investigated by neutron diffraction measurements on the powder sample. The Mn atoms are arranged on a simple cubic lattice, which splits into two face centred cubic sublattices so that the magnetic moments on one sublattice are antiparallel to those on the other. The magnetic moment of a Mn atom is close to 4 Bohr

  19. Aberration-corrected electron microscopy of nanoparticles and intermetallic compounds

    E-print Network

    Dunin-Borkowski, Rafal E.

    ), in combination with high-angle annular dark-field (HAADF) imaging, in the scanning transmission electron are of interest for oxygen reduction in proton-exchange-membrane fuel cells, will also be presented [4 with chromatic as well as spherical aberration correctors, to characterise electron-beam-sensitive materials

  20. NEUROTOXIC EFFECTS OF CONTROLLED EXPOSURE TO A COMPLEX MIXTURE OF VOLATILE ORGANIC COMPOUNDS

    EPA Science Inventory

    Subjective reactions of discomfort, impaired air quality, irritation of mucosal membranes, and impaired memory have been reported in chemically sensitive subjects during exposure to volatile organic compounds (VOC's) found in new buildings. 6 normal healthy male subjects aged 18-...

  1. Electrochemical and spectroelectrochemical investigations of rhodium and iridium complexes and group IV organometallic compounds

    SciTech Connect

    Gregory, T.P.

    1992-01-01

    The electron-transfer properties of a series of transition metal complexes were determined by electrochemical, ultraviolet-visible and infrared spectroelectrochemical, and synthetic investigations. The rhodium(III) complexes trans-[Rh(py)[sub 4]Cl[sub 2

  2. (Hydroxyacetyl)iridium and -rhodium complexes: model compounds for CO hydrogenation

    SciTech Connect

    Milstein, D.; Fultz, W.C.; Calabrese, J.C.

    1986-03-19

    Hydroxyacetyl complexes are postulated as intermediates in the direct conversion of synthesis gas to oxygenated products and in the hydroformylation of formaldehyde to glycolaldehyde, an ethylene glycol precursor. Whereas various hydroxymethyl complexes are now known, Fe(COCH/sub 2/OH)(P(OMe)/sub 3/)/sub 2/(CO)Cl obtained as an isomeric mixture is the only hydroxyacetyl complex reported and no (hydroxyacetyl)metal hydrides are known. A chelate-stabilized hydroxyacyl complex has been reported very recently. The lack of hydroxyacetyl complexes is perhaps due in part to difficulties in carbonylation of hydroxymethyl complexes. Here the synthesis of such complexes by oxidative addition reactions of 2,5-dihydroxy-1,4-dioxane (glycol aldehyde dimer) to Ir(I) and Rh(I) complexes is reported. This is the reversal of the postulated product-forming step in formaldehyde hydroformylation. 20 references, 2 figures.

  3. The ?3 model of acids and bases: extending the Lewis theory to intermetallics.

    PubMed

    Stacey, Timothy E; Fredrickson, Daniel C

    2012-04-01

    A central challenge in the design of new metallic materials is the elucidation of the chemical factors underlying the structures of intermetallic compounds. Analogies to molecular bonding phenomena, such as the Zintl concept, have proven very productive in approaching this goal. In this Article, we extend a foundational concept of molecular chemistry to intermetallics: the Lewis theory of acids and bases. The connection is developed through the method of moments, as applied to DFT-calibrated Hückel calculations. We begin by illustrating that the third and fourth moments (?(3) and ?(4)) of the electronic density of states (DOS) distribution tune the properties of a pseudogap. ?(3) controls the balance of states above and below the DOS minimum, with ?(4) then determining the minimum's depth. In this way, ?(3) predicts an ideal occupancy for the DOS distribution. The ?(3)-ideal electron count is used to forge a link between the reactivity of transition metals toward intermetallic phase formation, and that of Lewis acids and bases toward adduct formation. This is accomplished through a moments-based definition of acidity which classifies systems that are electron-poor relative to the ?(3)-ideal as ?(3)-acidic, and those that are electron-rich as ?(3)-basic. The reaction of ?(3) acids and bases, whether in the formation of a Lewis acid/base adduct or an intermetallic phase, tends to neutralize the ?(3) acidity or basicity of the reactants. This ?(3)-neutralization is traced to the influence of electronegativity differences at heteroatomic contacts on the projected DOS curves of the atoms involved. The role of ?(3)-acid/base interactions in intermetallic phases is demonstrated through the examination of 23 binary phases forming between 3d metals, the stability range of the CsCl type, and structural trends within the Ti-Ni system. PMID:22420716

  4. First-principles study of the binary intermetallics in the Au-Rb system

    NASA Astrophysics Data System (ADS)

    Benmechri, Achraf; Djaballah, Yassine; Amer, Ahmed Said; Belgacem-Bouzida, Aissa; Bouderba, Hichem

    2014-06-01

    First-principles calculations within density functional theory (DFT) with the projector augmented wave (PAW) technique were used to investigate the stabilities of intermetallics in the Au-Rb system at 0 K. Four intermetallics: Au7Rb3, Au3Rb2, Au5Rb and AuRb were investigated in their observed experimental structures. The Au2Rb compound, reported in the Au-Rb phase diagrams without specifying explicitly its structure, was also investigated by inspecting several hypothetical structures. A suspect compound (AuRb2) was also investigated. Results show that: (i) The Au3Rb2 and Au7Rb3 compounds, which were never reported in any Au-Rb phase diagram, are stable at 0 K. (ii) The Au2Rb compound is not a ground state for all the tested structures. (iii) Stability of the Au5Rb and AuRb compounds was confirmed. (iv) The new compound AuRb2, not yet reported experimentally, is found mechanically stable at 0 K.

  5. New 4234-type Intermetallic Borocarbides: Synthesis, Structure, and Magnetic Properties

    NASA Astrophysics Data System (ADS)

    Link, J. R.; Loureiro, S. M.; Kealhofer, C.; Zandbergen, H. W.; Cava, R. J.

    2002-03-01

    New 4234-type compounds, structurally related to the n=4 member of the (LnC)nNi2B2 homologous series of intermetallic borocarbides, were synthesized by arc-melting. Here we report that this structure type, previously observed only for Ni-based compounds, can be synthesized for a large number of transition elements. Further, we find it to be stable for medium through small lanthanides. The compounds have formulas Y4T2B3C4 [T=Fe, Co, Ni, Ru, Rh, and Ir], Ln4T2B3C4 [Ln=Er, Dy, and Gd; T=Fe and Co], Lu4Ni2B3C4, and Sc4Ni2B3C4. The unit cells are pseudo-tetragonal, with lattice parameters ranging from a=3.348(1) Å, c=25.90(1) Å for Sc4Ni2B3C4 to a=3.624(1) Å, c=26.63(1) Å for Y4Rh2B3C4. Structural investigation by exit-wave reconstruction is reported, showing the presence of twinning on the unit cell scale. The phases show either Curie- Weiss behavior with very small magnetic moments per transition metal atom or temperature-independent paramagnetism.

  6. A Study on the Formation of Intermetallics During the Heat Treatment of Explosively Welded Al-Ti Multilayers

    NASA Astrophysics Data System (ADS)

    Foadian, Farzad; Soltanieh, Mansour; Adeli, Mandana; Etminanbakhsh, Majid

    2014-04-01

    Metallic-intermetallic laminate composites are promising materials for many applications, namely, in the aerospace industry. Ti/TiAl3 laminates are one of the interesting laminate composites, which are mostly used in aerospace applications. In this work, commercially pure aluminum and titanium sheets were explosively joined. The multilayer samples were annealed between 1 and 260 hours at 903 K (630 °C) in ambient atmosphere, and the formation and growth of the intermetallic compound at the Ti/Al interface were monitored. Microstructural investigations were carried out using optical and scanning electron microscopes equipped with energy-dispersive spectroscopy and the X-ray diffraction technique. The microhardness profile of the layers was also determined. The thickness and type of Al-Ti intermetallics were determined. It was found that the only intermetallic phase observed in the interfaces was TiAl3. It was also shown that two mechanisms for TiAl3 growth exist: reaction and diffusion controlled. The growth exponent was equal to 0.94 for the reaction-controlled mechanism (first step) and 0.31 for the diffusion-controlled mechanism (second step). These values were in good agreement with theoretical values (1 and 0.5 for the first and second steps, respectively). Based on the results of this research, a kinetic model for the formation and growth of TiAl3 intermetallic phase was proposed.

  7. Hirsutellones and beyond: figuring out the biological and synthetic logics toward chemical complexity in fungal PKS-NRPS compounds.

    PubMed

    Li, Xu-Wen; Ear, Alexandre; Nay, Bastien

    2013-06-01

    Covering: up to early 2013. Fungal polyketides and their hybrid non ribosomal peptide derivatives are characterized by often striking structural features and biological activities. Their diversity and their complexity arise from highly organized and programmable biosynthetic pathways and have been challenged by many synthetic chemists. This review will conceptually illustrate how complexity can be generated, starting from a general biosynthetic purpose (the fundaments of PKS-NRPS assembly lines) and finally showing how the particular class of hirsutellone compounds has emerged from such processes in relation to post-elongation and secondary tailoring events. Synthetic efforts to produce these natural products will be described with a special emphasis on complexity-generating strategies and steps. Thus, the biosynthetic and synthetic works will be analyzed in a continuous flow, focusing on both the logic of Nature and organic chemists. PMID:23640165

  8. Site preference, magnetism and lattice vibrations of intermetallics Lu?Fe17–xTx (T=Cr, Mn, Ru)

    SciTech Connect

    Li, Jin-Chun [Institute of Applied Physics, University of Science and Technology Beijing, Beijing 100083 (China); Qian, Ping, E-mail: qianpinghu@sohu.com [Institute of Applied Physics, University of Science and Technology Beijing, Beijing 100083 (China); Zhang, Zhen-Feng [Institute of Applied Physics, University of Science and Technology Beijing, Beijing 100083 (China); Yuan, Xiao-Jian [Department of Applied Physics, Hunan University, Changsha 410082 (China); Wang, Yi-Wen; Shen, Jiang [Institute of Applied Physics, University of Science and Technology Beijing, Beijing 100083 (China); Chen, Nan-Xian [Institute of Applied Physics, University of Science and Technology Beijing, Beijing 100083 (China); Department of Physics, Tsinghua University, Beijing 100084 (China)

    2013-05-01

    We present an atomistic study on the phase stability, site preference and lattice constants of the rare earth intermetallics Lu?Fe17–xTx (T=Cr, Mn, Ru). The calculated preferential occupation site of ternary element T is found to be the 4f site. The order of site preference is given as 4f, 12k, 12j and 6g for Lu?Fe17–xTx. The calculated lattice parameters are corresponding to the experimental results. We have calculated the magnetic moments of Lu?Fe17–xTx compounds. Results show that the calculated total magnetic moment of Lu?Fe?? compound is M=37.34 ?B/f.u. In addition, the total and partial phonon densities of states are evaluated first for these complicated structures. - Graphical abstract: The vibrational modes are mostly excited by Fe atoms, Lu contributes to the lower frequencies modes, and the contribution of Ru atoms is the same as Fe atoms. Highlights: • There are no reports on lattice vibrations of Lu?(Fe, T)17–x (T=Cr, Mn, Ru) compounds. • The phase stability and site preference are evaluated first for the complex structures of Lu?(Fe, T)17–x (T=Cr, Mn, Ru) compounds. • The lattice inversion method to obtain the interatomic pair potential is the unique one.

  9. Crystal structures of multidrug-resistant HIV-1 protease in complex with two potent anti-malarial compounds

    SciTech Connect

    Yedidi, Ravikiran S.; Liu, Zhigang; Wang, Yong; Brunzelle, Joseph S.; Kovari, Iulia A.; Woster, Patrick M.; Kovari, Ladislau C.; Gupta, Deepak (LECOM); (WSI); (NWU); (MUSC); (WSU)

    2012-06-19

    Two potent inhibitors (compounds 1 and 2) of malarial aspartyl protease, plasmepsin-II, were evaluated against wild type (NL4-3) and multidrug-resistant clinical isolate 769 (MDR) variants of human immunodeficiency virus type-1 (HIV-1) aspartyl protease. Enzyme inhibition assays showed that both 1 and 2 have better potency against NL4-3 than against MDR protease. Crystal structures of MDR protease in complex with 1 and 2 were solved and analyzed. Crystallographic analysis revealed that the MDR protease exhibits a typical wide-open conformation of the flaps (Gly48 to Gly52) causing an overall expansion in the active site cavity, which, in turn caused unstable binding of the inhibitors. Due to the expansion of the active site cavity, both compounds showed loss of direct contacts with the MDR protease compared to the docking models of NL4-3. Multiple water molecules showed a rich network of hydrogen bonds contributing to the stability of the ligand binding in the distorted binding pockets of the MDR protease in both crystal structures. Docking analysis of 1 and 2 showed a decrease in the binding affinity for both compounds against MDR supporting our structure-function studies. Thus, compounds 1 and 2 show promising inhibitory activity against HIV-1 protease variants and hence are good candidates for further development to enhance their potency against NL4-3 as well as MDR HIV-1 protease variants.

  10. Complex formation of uranium(VI) with 4-hydroxy-3-methoxybenzoic acid and related compounds

    Microsoft Academic Search

    D. Vulpius; G. Geipel; L. Baraniak; A. Rossberg; G. Bernhard

    2006-01-01

    Summary  The complex formation of uranium(VI) with 4-hydroxy-3-methoxybenzoic acid as well as with benzoic acid and 4-hydroxybenzoic\\u000a acid was studied. In aqueous solution weak carboxylic 1 : 1 complexes, are formed in which the carboxyl group is bidentately\\u000a coordinated to the metal atom. The logarithmic stability constants of these complexes regarding the reaction of the uranyl\\u000a ion with the single charged

  11. Spectral studies and thermal analysis of new vanadium complexes of ethanolamine and related compounds

    NASA Astrophysics Data System (ADS)

    Masoud, Mamdouh S.; Ali, Alaa E.; Ahmed, Hytham M.; Mohamed, Essam A.

    2013-10-01

    The electronic absorption spectral behaviors of newly synthesized complexes of VIII, VIV and VO2+ with Ethanolamine, Diethanolamine and Triethanolamine were described. The complexes have been characterized by elemental analyses, magnetic moment measurements, IR and UV-Vis spectroscopy. Absorption spectra in seven different solvents were recorded. The solvatochromism was examined and discussed. Dipolar interactions between the solvent and the complexes were used to correlate the observed spectral shifts to solvent polarity. Some of the obtained complexes were studied by thermal analysis using DTA and TG techniques.

  12. Machinability of a nickel aluminide intermetallic alloy

    Microsoft Academic Search

    S. Chatterjee

    1993-01-01

    This article reports the results of an experimental study on the machinability of a nickel aluminide intermetallic alloy.\\u000a Machining was conducted at various speeds, and results indicate low material removal rates. Chips collected for each test\\u000a run were measured for thickness for shear angle calculation and were subsequently observed microscopically. Chip segmentation\\u000a was observed microscopically, and a fluctuation in the

  13. Arc Casting Intermetallic Alloy (Materials Preparation Center)

    SciTech Connect

    None

    2010-01-01

    Arc casting of intermetallic (La-Ni-Sn) AB5 alloy used for metal hydride hydrogen storage. Upon solidification the Sn is partially rejected and increases in concentration in the remaining liquid. Upon completing solidification there is a great deal of internal stress in the ingot. As the ingot cools further the stress is relieved. This material was cast at the Ames Laboratorys Materials Preparation Center http://www.mpc.ameslab.gov

  14. Synthesis of intermetallics by mechanical alloying

    Microsoft Academic Search

    C. Suryanarayana; K. Russell; C.-G. Li

    1995-01-01

    Mechanical alloying (MA), a solid-state powder processing method, is a “far from equilibrium” synthesis technique which allows the development of novel crystal structures and microstructures, leading to enhanced physical and mechanical properties. The application of MA to the synthesis of intermetallics in the Ti?Al(?Nb), Al?Fe, Nb?Al, Ti?Mg, Al?Zr(?Fe) and Al?Mg systems is presented. The ability to synthesize a variety of

  15. A NEW MASS SPECTROMETRIC TECHNIQUE FOR IDENTIFYING TRACE-LEVEL ORGANIC COMPOUNDS IN COMPLEX MIXTURES

    EPA Science Inventory

    Most organic compounds are not found in mass spectral libraries and cannot be easily identified from low resolution mass spectra. Ion Composition Elucidation (ICE) utilizes selected ion recording with a double focusing mass spectrometer in a new way to determine exact mas...

  16. Implications for complex cognition from the hafting of tools with compound adhesives in the Middle Stone Age, South Africa

    PubMed Central

    Wadley, Lyn; Hodgskiss, Tamaryn; Grant, Michael

    2009-01-01

    Compound adhesives made from red ochre mixed with plant gum were used in the Middle Stone Age (MSA), South Africa. Replications reported here suggest that early artisans did not merely color their glues red; they deliberately effected physical transformations involving chemical changes from acidic to less acidic pH, dehydration of the adhesive near wood fires, and changes to mechanical workability and electrostatic forces. Some of the steps required for making compound adhesive seem impossible without multitasking and abstract thought. This ability suggests overlap between the cognitive abilities of modern people and people in the MSA. Our multidisciplinary analysis provides a new way to recognize complex cognition in the MSA without necessarily invoking the concept of symbolism. PMID:19433786

  17. Medicinal herb extract and a single-compound drug confer similar complex pharmacogenomic activities in mcf-7 cells.

    PubMed

    Yang, Ning-Sun; Shyur, Lie-Fen; Chen, Chih-Huai; Wang, Sheng-Yang; Tzeng, Chi-Meng

    2004-01-01

    Metabolite profiling and DNA microarray analysis of global gene expression profiles were employed to characterize the bioactivities of the herbal extract of Anoectochilus formosanus (AF), a popular folk medicine with anticancer activity, in MCF-7 cancer cells. The pharmacogenomic activities of this plant extract as a crude phytocompound mixture were compared to those conferred by the single-compound drug, plumbagin. A similar level of complexity in transcriptional regulation at the genomic level was observed for both AF extract- and plumbagin-treated MCF-7 cells, as revealed by the number of up- or downregulated genes as well as by the specific but distinct patterns found in the gene-clustering analysis. This finding offers evidence to support the search for fractionated medicinal herb extracts or phytocompound mixtures, in addition to single-compound drugs, as defined therapeutic agents. PMID:15067226

  18. Intermetallic phase formation in thin solid-liquid diffusion couples

    Microsoft Academic Search

    F. Bartels; J. W. Jr. Morris; G. Dalke; W. Gust

    1994-01-01

    Conducting joints with low fabrication temperatures and high thermal stability are useful in modern electronics. This paper\\u000a discusses the potential use of intermetallic phases in making such joints. Thin interconnection layers that consist entirely\\u000a of intermetallic phases have been produced by joining planar Cu substrates that are coated with thin films of Sn. Thin layers\\u000a (1-5 m) of intermetallic phase

  19. Tribological properties of FeAl intermetallics under dry sliding

    Microsoft Academic Search

    Jun Yang; Peiqing La; Weimin Liu; Qunji Xue

    2004-01-01

    The tribological properties of FeAl intermetallics under dry sliding against AISI52100 steel at ambient conditions were studied on an Optimol SRV oscillating friction and wear tester in a ball-on-disc contact configuration. Effects of load and sliding speed on tribological properties of the FeAl intermetallics were investigated. The worn surfaces of the FeAl intermetallics were examined with a scanning electron microscopy

  20. Polymer complexes. LVII. Supramolecular assemblies of novel polymer complexes of dioxouranium(VI) with some substituted allyl azo dye compounds

    NASA Astrophysics Data System (ADS)

    Diab, M. A.; El-Sonbati, A. Z.; El-Bindary, A. A.; Balboula, M. Z.

    2013-05-01

    A novel method to synthesize some dioxouranium(VI) polymer complexes of the general formula [UO2(Ln)2(OAc)2] (where HLn = azo allyl rhodanine). The structure of the novel mononuclear dioxoutranium(VI) polymer complexes was characterized using elemental analysis, spectral (electronic, infrared, 1H &13C NMR) studies, magnetic susceptibility measurements and thermal analysis. The molar conductivities show that all the polymer complexes are non-electrolytes. The IR showed that the ligand HLn act as bidentate neutral through carbonyl group and imine group nitrogen atom forming thereby a six-membered chelating ring and concomitant formation of an intramolecular hydrogen bond. The ?3 frequency of UO2+2 has been shown to be an excellent molecular probe for studying the coordinating power of the ligands. The values of ?3 of the prepared complexes containing UO2+2 were successfully used to calculate the force constant, FUO (10-8 N/Å) and the bond length RUO (Å) of the Usbnd O bond. A strategy based upon both theoretical and experimental investigations has been adopted. The theoretical aspects are described in terms of the well-known theory of 5d-4f transitions. Wilson's, matrix method, Badger's formula, and Jones and El-Sonbati equations were used to calculate the Usbnd O bond distances from the values of the stretching and interaction force constants. The most probable correlation between Usbnd O force constant to Usbnd O bond distance were satisfactorily discussed in term of Badger's rule and the equations suggested by Jones and El-Sonbati. The effect of Hammet constant is also discussed.

  1. Process for recovering niobium and\\/or tantalum compounds from such ores further containing complexes of uranium, thorium, titanium and\\/or rare earth metals

    Microsoft Academic Search

    B. Krismer; A. Hoppe

    1984-01-01

    A process for recovering one or more nonradioactive transition metal compounds from an ore containing one or more compounds of said transition metal or metals and further containing at least one complex of a member selected from the group consisting of uranium, thorium, radium, titanium, and rare earth metals, comprises decomposing said ore in crushed condition by means of an

  2. Process for recovering niobium and\\/or tantalum metal compound from such ores further containing complexes of uranium, thorium, titanium and\\/or rare earth metals

    Microsoft Academic Search

    W. Floeter; G. Schoening; K. Schroeer

    1984-01-01

    A process for recovering one or more non-radioactive transition metal compounds from an ore containing one or more compounds of said transition metal or metals and further containing at least one complex of a member selected from the group consisting of uranium, thorium, radium, titanium, and rare earth metals, which comprises decomposing said ore in crushed condition by means of

  3. Design and synthesis of novel complexes containing N-phenyl-1H-pyrazole moiety: Ni complex as potential antifungal and antiproliferative compound.

    PubMed

    El-Gamel, Nadia E A; Farghaly, Thoraya A

    2013-11-01

    Cu(II) (1), Ni(II) (2), Cr(III) (3) and Fe(III) (4) complexes with 3-acetyl-4-benzoyl-1-phenyl-1H-pyrazole (L1) were prepared and structurally characterized. Usual coordination of L1 was achieved through nitrogen of pyrazole moiety and carbonyl acetyl group. Electronic spectra of the complexes indicate that the geometry of the metal center was six coordinate octahedral. In vitro antimicrobial activity of the ligand and complex compounds was screened in terms of antibacterial effect on Staphylococcus aureus (Gram-positive), Escherichia coli (Gram-negative) and antifungal effect on the fungi Aspergillus flavus and candida albicans using the modified Kirby-Bauer disc diffusion and minimum inhibitory concentrations (MIC) methods. Ni(II) complex (2) exhibited remarkable antifungal inhibition against Candida albicans equal to the standard antifungal agent. To continue our study some structural modifications are formed by adding 4-fluoro-benzoyl moiety to L1 in different forms to produce different ligands, 3-acetyl-4-(4-flourobenzoyl)-1-phenyl-1H-pyrazole (L2) and 3-[(3-acetyl-1-phenyl-1H-4-pyrazolyl)carbonyl]-1-phenyl-4-(4-flourobenzoyl)-1H-pyrazole (L3), Ni complexes (5 and 6) are prepared and comparable in vitro antimicrobial study is evaluated. In vitro cytotoxicity of the Ni(II) complex (2) is studied using MTT assay. The analysis of the cell test showed that (2) displayed quite small cytotoxic response at the higher concentration level which indeed would further enable us for more opportunities in therapeutic and biomedical challenges. Both of the capability as a potent in vitro antifungal agent and the cell test analysis show Ni(II) complex (2) as a promising material in the translation of observed in vitro biological phenomenon into clinical therapies settings. PMID:23871973

  4. Determination of solubility products of complex compounds of certain lanthanide and actinide diiodies with 18-crown-6 in tetrahydrofuran

    SciTech Connect

    Mikheev, N.B.; Kamenskaya, A.N.; Kulyukhin, S.A.

    1988-09-01

    The existence of divalent americium in a tetrahydrofuran (THF) solution was proved for the first time. The values of the solubility products (SP) of the complex compounds with the composition of MeI{sub 2}{centered dot}18-crown-6 (Me = Sm, Eu, Yb, Am, Cf, Es, Fm) in the THF solutions were determined by the cocrystallization method. The SP values obtained are within (5.9-7.9){centered dot}10{sup {minus}12} and are close to the SP value for SrI{sub 2}{centered dot}10{sup {minus}12}, which indicates a similarity in the properties of these elements.

  5. Draft genomes of three Antarctic Psychrobacter strains producing antimicrobial compounds against Burkholderia cepacia complex, opportunistic human pathogens.

    PubMed

    Fondi, Marco; Orlandini, Valerio; Perrin, Elena; Maida, Isabel; Bosi, Emanuele; Papaleo, Maria Cristiana; Michaud, Luigi; Lo Giudice, Angelina; de Pascale, Donatella; Tutino, Maria Luisa; Liò, Pietro; Fani, Renato

    2014-02-01

    Herein we present the draft genomes of three Psychrobacter strains isolated from Antarctic sponges and able to inhibit the growth of bacteria belonging to the Burkholderia cepacia complex, responsible for infections of the respiratory system in patients affected by Cystic Fibrosis. The comparative analysis of the annotated genomes of these Psychrobacter strains highlighted their differences in terms of overall genomic content (e.g. shared gene sets) and allowed the identification of gene clusters hypothetically involved in the biosynthesis of antimicrobial compounds. PMID:24401162

  6. Excitonic correlations in the intermetallic Fe2VAl

    NASA Astrophysics Data System (ADS)

    Weht, Ruben; Pickett, W. E.

    1998-09-01

    The intermetallic compound Fe2VAl looks nonmetallic in transport and strongly metallic in thermodynamic and photoemission data. It has in its band structure a highly differentiated set of valence and conduction bands leading to a semimetallic system with a very low density of carriers. The pseudogap itself is sensitive to the presence of Al states, but the resulting carriers have only minor Al character. The effects of generalized gradient corrections to the local density band structure are shown to be important, reducing the carrier density by a factor of 3. Spin-orbit coupling results in a redistribution of the holes among pockets at the Brillouin zone center. Doping of this nonmagnetic compound by 0.5 electrons per cell in a virtual crystal fashion results in a moment of 0.5?B and destroys the pseudogap. We assess the tendencies toward the formation of an excitonic condensate and toward an excitonic Wigner crystal and find both to be unlikely. We propose a model in which the observed properties result from excitonic correlations arising from two interpenetrating lattices of distinctive electrons (eg on V) and holes (t2g on Fe) of low density (one carrier of each sign per 350 formula units).

  7. Oxidation of organosulfur compounds by hydrogen peroxide in the presence of niobium and vanadium peroxo complexes

    Microsoft Academic Search

    Tkhai Fam Vin’; A. V. Tarakanova; O. V. Kostyuchenko; B. N. Tarasevich; N. S. Kulikov; A. V. Anisimov

    2008-01-01

    New niobium(V) peroxo complexes containing aspargine and Schiff base ligands were synthesized, and their structures were solved\\u000a by IR, NMR, and mass spectrometric methods. They were found to be catalytically active for the peroxidation of methyl phenyl\\u000a sulfide and benzothiophene to the corresponding sulfoxide and sulfones. It was shown that vanadium(V) peroxo complexes with\\u000a the same ligands are less active

  8. Chiral phosphites as ligands in asymmetric metal complex catalysis and synthesis of coordination compounds

    NASA Astrophysics Data System (ADS)

    Gavrilov, Konstantin N.; Bondarev, Oleg G.; Polosukhin, Aleksei I.

    2004-07-01

    The data published during the last five years on the application of chiral derivatives of phosphorous acid in coordination chemistry and enantioselective catalysis are summarised and discussed. The effect of the nature of these ligands on the structure of metal complexes and on the efficiency of catalytic organic syntheses is shown. Hydroformylation, hydrogenation, allylic substitution and conjugate addition catalysed by transition metal complexes with optically active phosphites and hydrophosphoranes are considered. The prospects for the development of this field of research are demonstrated.

  9. A structural, magnetic, and Mssbauer spectral study of the TbCo4-xFexB compounds with x=0, 1, and 2

    E-print Network

    Paris-Sud XI, Université de

    of the fundamental structural properties of intermetallic com- pounds. The addition of a ternary component, such as boron or carbon, to an intermetallic binary RM compound can lead to a new ternary structure andA structural, magnetic, and Mössbauer spectral study of the TbCo4-xFexB compounds with x=0, 1

  10. Radionuclide-binding compound, a radionuclide delivery system, a method of making a radium complexing compound, a method of extracting a radionuclide, and a method of delivering a radionuclide

    DOEpatents

    Fisher, Darrell R. (Richland, WA); Wai, Chien M. (Moscow, ID); Chen, Xiaoyuan (Moscow, ID)

    2000-01-01

    The invention pertains to compounds which specifically bind radionuclides, and to methods of making radionuclide complexing compounds. In one aspect, the invention includes a radionuclide delivery system comprising: a) a calix[n]arene-crown-[m]-ether compound, wherein n is an integer greater than 3, and wherein m is an integer greater than 3, the calix[n]arene-crown-[m]-ether compound comprising at least two ionizable groups; and b) an antibody attached to the calix[n]arene-crown-[m]-ether compound. In another aspect, the invention includes a method of making a radium complexing compound, comprising: a) providing a calix[n]arene compound, wherein n is an integer greater than 3, the calix[n]arene compound comprising n phenolic hydroxyl groups; b) providing a crown ether precursor, the crown ether precursor comprising a pair of tosylated ends; c) reacting the pair of tosylated ends with a pair of the phenolic hydroxyl groups to convert said pair of phenolic hydroxyl groups to ether linkages, the ether linkages connecting the crown ether precursor to the calix[n]arene to form a calix[n]arene-crown-[m]-ether compound, wherein m is an integer greater than 3; d) converting remaining phenolic hydroxyl groups to esters; e) converting the esters to acids, the acids being proximate a crown-[m]-ether portion of the calix[n]arene-crown-[m]-ether compound; and f) providing a Ra.sup.2+ ion within the crown-[m]-ether portion of the calix[n]arene-crown-[m]-ether compound.

  11. IR spectra of cyclic hydrogen-bonded complexes of bifunctional nitrogen compounds in solution

    NASA Astrophysics Data System (ADS)

    Bureiko, S. F.; Kucherov, S. Yu.

    2010-12-01

    We measured the IR absorption spectra of self-associates and complexes with carboxylic acids of 3,5-dimethylpyrazole (DMP), diphenylformamidine (DPFA), diphenyltriazene (DPT), and diphenylguanidine (DPG) in solutions in a wide range of concentrations and temperatures and calculated spectroscopic, geometric, and energy characteristics of complexes in the quantum-mechanical harmonic and anharmonic 1D and 2D approximations. Spectroscopic data show that, in the case of DMP, cyclic trimers are predominantly formed; DPFA and DPG form cyclic dimers with two NH...N bonds in inert solvents, whereas, upon the complexation of DPT, cyclic structures do not occur, and only open dimers are formed. Upon the interaction of DMP, DPFA, and DPT with weak carboxylic acids (HCOOH, CH3COOH, CH2ClCOOH) in CCl4 or in CH2Cl2, molecular cyclic structures with NH...O=C and OH...N H-bonds are formed, whereas cyclic dimer complexes with stronger acids (CHCl2COOH, CCl3COOH, CF3COOH) predominantly have the structure of hydrogen-bonded ion pairs with proton transfer from the hydroxyl group to the proton-acceptor nitrogen atom. The calculations of the structure and vibrational frequencies using various basis sets of atomic functions confirm the formation of cyclic complexes in accordance with experimental results and, in the case of interaction with strong carboxylic acids, the proton transfer along the OH...N hydrogen bridge.

  12. Crystal Structure of Patatin-17 in Complex with Aged and Non-Aged Organophosphorus Compounds

    PubMed Central

    Wijeyesakere, Sanjeeva J.; Richardson, Rudy J.; Stuckey, Jeanne A.

    2014-01-01

    Patatin is a non-specific plant lipase and the eponymous member of a broad class of serine hydrolases termed the patatin-like phospholipase domain containing proteins (PNPLAs). Certain PNPLA family members can be inhibited by organophosphorus (OP) compounds. Currently, no structural data are available on the modes of interaction between the PNPLAs and OP compounds or their native substrates. To this end, we present the crystal structure of patatin-17 (pat17) in its native state as well as following inhibition with methyl arachidonyl fluorophosphonate (MAFP) and inhibition/aging with diisopropylphosphorofluoridate (DFP). The native pat17 structure revealed the existence of two portals (portal1 and portal2) that lead to its active-site chamber. The DFP-inhibited enzyme underwent the aging process with the negatively charged phosphoryl oxygen, resulting from the loss of an isopropyl group, being within hydrogen-binding distance to the oxyanion hole. The MAFP-inhibited pat17 structure showed that MAFP did not age following its interaction with the nucleophilic serine residue (Ser77) of pat17 since its O-methyl group was intact. The MAFP moiety is oriented with its phosphoryl oxygen in close proximity to the oxyanion hole of pat17 and its O-methyl group located farther away from the oxyanion hole of pat17 relative to the DFP-bound state. The orientation of the alkoxy oxygens within the two OP compounds suggests a role for the oxyanion hole in stabilizing the emerging negative charge on the oxygen during the aging reaction. The arachidonic acid side chain of MAFP could be contained within portals 1 or 2. Comparisons of pat17 in the native, inhibited, and aged states showed no significant global conformational changes with respect to their C? backbones, consistent with observations from other ?/? hydrolases such as group VIIA phospholipase A2. PMID:25248161

  13. The s-p bonded representatives of the prominent BaAl4 structure type: a case study on structural stability of polar intermetallic network structures.

    PubMed

    Häussermann, Ulrich; Amerioun, Shahrad; Eriksson, Lars; Lee, Chi-Shen; Miller, Gordon J

    2002-04-24

    This work presents a detailed, combined experimental and theoretical study on the structural stability of s-p bonded compounds with the BaAl4 structure type (space group I4/mmm, Z = 2) as part of a broad program to investigate the complex questions of structure formation and atomic arrangements in polar intermetallics. From ab initio calculations employing pseudopotentials and a plane wave basis set, we extracted optimized structural parameters, binding energies, and the electronic structure of the systems AeX(III)4, AeX(II)2X(IV)2, AeX(II)2X(III)2 (Ae = Ca, Sr, Ba; X(II) = Mg, Zn; X(III) = Al, Ga; X(IV) = Si, Ge). For all systems we found a pronounced pseudo-gap in the density of states separating network X42- bonding from antibonding electronic states that coincides with the Fermi level for an electron count of 14 electrons per formula unit, the optimum value for stable BaAl4-type polar intermetallics. However, the synthesis and structural characterization (from X-ray single crystal and powder diffraction data) of the new compounds AeZn2-Al2+, AeZn2-deltaGa2+delta (Ae = Ca, Sr, Ba; delta = 0-0.2) and AeMg0.9Al3.1, AeMg1.7Ga2.3 (Ae = Sr, Ba) manifested that electron deficiency is rather frequent for BaAl4-type polar intermetallics. The site preference for different "X" elements in the ternary systems was quantified by calculating "coloring energies", which, for some systems, was strongly dependent on the size of the electropositive Ae component. The Ae2+ cations decisively influence the nearest neighbor distances in the encapsulating polyanionic networks X4(2-) and the structures of these networks are surprisingly flexible to the size of the Ae component without changing the overall bonding picture. A monoclinically distorted variant of the BaAl4 structure occurs when the cations become too small for matching the size of encapsulating X4(2-) cages. An even larger size mismatch leads to the formation of the EuIn4 structure type. PMID:11960466

  14. Complexation of estragole as pure compound and as main component of basil and tarragon essential oils with cyclodextrins.

    PubMed

    Kfoury, Miriana; Auezova, Lizette; Ruellan, Steven; Greige-Gerges, Hélène; Fourmentin, Sophie

    2015-03-15

    Inclusion complexes of estragole (ES) as pure compound and as main component of basil and tarragon essential oils (EOs) with ?-cyclodextrin (?-CD), ?-cyclodextrin (?-CD), hydroxypropyl-?-cyclodextrin (HP-?-CD), randomly methylated-?-cyclodextrin (RAMEB), a low methylated-?-cyclodextrin (CRYSMEB) and ?-cyclodextrin (?-CD) were characterized. Formation constants (Kf) of the complexes were determined in aqueous solution by nonlinear regression analysis using static headspace gas chromatography (SH-GC) and UV-visible spectroscopy. Solid inclusion complexes were prepared by the freeze-drying method for different CD:ES molar ratios and were characterized by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR). Inclusion complexes formation allowed the controlled release of ES. Moreover, increased DPPH radical scavenging activity and photostability of ES and ES containing EOs (ESEOs) were observed in the presence of CDs. These findings suggest that encapsulation with CDs could be an efficient tool to improve the use of ES and ESEOs in aromatherapy, cosmetic and food fields. PMID:25542121

  15. Circular dichroism sensing of chiral compounds using an achiral metal complex as probe.

    PubMed

    Irfanoglu, Burcin; Wolf, Christian

    2014-08-01

    Coordination of a chiral substrate to (meso-salen)cobalt(II) nitrate and subsequent oxidation generates a Co(III) complex exhibiting a strong chiroptical readout that is attributed to spontaneous substrate-to-ligand chirality imprinting. The characteristic circular dichroism (CD) response of the (salen)cobalt complex can be used for enantiomeric analysis of a variety of chiral substrates based on a simple CD measurement at low concentration and without additional purification steps. This chirality sensing approach has potential for high-throughput enantiomeric excess (ee) screening applications and minimizes solvent waste production. PMID:24839183

  16. Stress-Induced Martensitic Phase Transformation in Intermetallic Nickel

    E-print Network

    Lin, Xi

    Stress-Induced Martensitic Phase Transformation in Intermetallic Nickel Aluminum Nanowires Harold S simulations are utilized to demonstrate a stress-induced martensitic phase transformation in intermetallic or actuator has exploded in recent years. Nanowires are one nanoscale structural element that has shown

  17. Ruthenium-complex-catalyzed regio- and stereoselective linear codimerization of 2-norbornenes with acrylic compounds.

    PubMed

    Ura, Yasuyuki; Tsujita, Hiroshi; Wada, Kenji; Kondo, Teruyuki; Mitsudo, Take-aki

    2005-08-19

    A linear codimerization of 2-norbornenes with acrylic compounds such as acrylates and an acrylamide proceeded efficiently by ruthenium catalyst systems, RuCl3(tpy)/Zn (tpy = 2,2':6',2' '-terpyridine) or [RuCl2(C6H6)]2/Zn in a primary or secondary alcoholic solvent, to afford the corresponding exo-trans-2-norbornylacrylates as major products regio- and stereoselectively along with a small amount of cis isomers. The reaction of 2,5-norbornadiene with methyl acrylate also gave the linear exo-trans codimer, which was effectively catalyzed by the addition of triarylphosphines to the RuCl3(tpy)/Zn catalyst system. PMID:16095279

  18. Evaluations of an Enhanced Total Hydrocarbon Analyzer With Complex Mixtures of Volatile Organic Compounds

    NASA Technical Reports Server (NTRS)

    Cross, John H.; Limero, Thomas F.; James, John T.; Breach, James; Hinton, Mark

    1995-01-01

    From the earliest manned missions, the volatile organic compound (VOC) content of spacecraft air has been a concern because of a much greater potential for contamination than air in most terrestrial settings. First, the volume of air is small compared to the mass of man- made materials comprising the interior furnishings of the spacecraft. These man-made materials offgas VOCs trapped during manufacture. Second, the nitrogen fraction of the air is recycled. Any VOCs not scrubbed out with charcoal filters or aqueous condensate (mainly water expired by the crew) will accumulate in the air. Third, the crew emits metabolic VOCs. Fourth, experimental payloads can also offgas or accidentally release a VOC; in fact a major organic constituent of the atmosphere is the disinfectant isopropanol released from swabs used in medical experiments.

  19. Thermal,spectral and biological properties of Zn(II) complex compounds with phenazone

    Microsoft Academic Search

    Erika Szunyogová; Katarína Györyová; Daniela Hudecová; Lenka Piknová; J. Chomi?; Zuzanna Vargová; V. Zele?ák

    2007-01-01

    The thermal decomposition of the complexes Zn(form)2?2phen\\u000a (I), Zn(ac)2?2phen\\u000a (II), Zn(prop)2?2phen\\u000a (III), Zn(but)2?2phen\\u000a (IV), where phen=phenazone, form=formiate,\\u000a ac=acetate, prop=propionate, but=butyrate has been studied in air by TG\\/DTG\\u000a and DTA methods. The possible mechanism of the thermal decomposition was proposed.\\u000a The final product of thermal decomposition was ZnO. IR data show unidentate\\u000a coordination of carboxylate group to Zn(II) ion. The complexes

  20. An on-line HPLC method for detection of radical scavenging compounds in complex mixtures

    Microsoft Academic Search

    Irina I. Koleva; Harm A. G. Niederländer; Beek van T. A

    2000-01-01

    A rapid on-line method for screening of complex mixtures for radical scavenging components was developed using a methanolic solution of 2,2'-diphenyl-1-picrylhydrazyl (DPPH) stable free radical. The HPLC-separated analytes react postcolumn with the DPPH solution, and the induced bleaching is detected as a negative peak by an absorbance detector at 517 nm. An optimized instrumental setup is presented. The method is

  1. Determination of thermodynamic and thermo-elastic properties for ductile B2-DyCu intermetallics using molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Wu, Yurong; Xu, Longshan; Hu, Wangyu

    2015-02-01

    The thermodynamic and thermo-elastic properties of ductility intermetallic compounds DyCu with B2 structure are investigated with molecular dynamics. The calculated structural properties are in reasonable agreement with the available experimental and previously calculated data. At 300 K, the heat capacity of DyCu is 23.93 J mol-1 K-1. At the whole range 0-900 K, the elastic constants decrease with increasing temperature, and satisfy the stability criterions for DyCu compound. The value of B/G ratio for DyCu is greater than 1.75 implying the DyCu intermetallics are ductile, and increases with elevating temperature. Our results mean that the ductility of DyCu can be improved by increasing temperature.

  2. Hyperfine interactions in the mixed ligand complexes of phenolic compounds with iron phthalimide

    NASA Astrophysics Data System (ADS)

    Sharma, C. L.; Samuel, K. J.; Garg, V. K.; Singh, B. P.

    1987-04-01

    Six new mixed ligand complexes of iron phthalimide with gallic acid, pyridoxine, sulphosalicylic acid, salicylaldehyde, anisaldehyde, and naphthaldehyde have been prepared and characterised on the basis of conductance, magnetic susceptibility, IR, electronic and Mössbauer spectroscopic studies. The room temperature Mössbauer spectra exhibit a broad and asymmetric doublet which persists down to 50 K. The I. S. and Q. S. values indicate iron to be in +3 and high spin state. The magnetic moment values (˜5.0 BM at 300 K decreasing to ˜ 3.0 BM at 77 K) do not show any magnetic transition.

  3. Ab initio study of the structural, thermodynamic and electronic properties of the Cu 10In 7 intermetallic phase

    Microsoft Academic Search

    S. Ramos de Debiaggi; G. F. Cabeza; C. Deluque Toro; A. M. Monti; S. Sommadossi; A. Fernández Guillermet

    2011-01-01

    The physico-chemical properties of the intermetallic phases in the Cu–In system have been a matter of considerable theoretical and experimental interest in connection with, i.a., the application of In–Sn alloys as lead-free micro-soldering alloys. Recently, a new binary compound with the chemical formula Cu10In7 has been detected in a study of the ?-phase field. The structure of the Cu10In7 phase

  4. Journal of Alloys and Compounds 524 (2012) 5358 Contents lists available at SciVerse ScienceDirect

    E-print Network

    Melnik, Roderick

    2012-01-01

    t Structural, elastic and electronic properties, as well as heats of formation, of seven Ca­Zn intermetallicDirect Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jallcom Structural, elastic, electronic properties and heats of formation of Ca­Zn intermetallics from first principles calculations

  5. [High pressure self-propagating synthesis applied to intermetallics of the nickel-aluminum type

    SciTech Connect

    Dumez, M.C.; Marin-Ayral, R.M.; Tedenac, J.C. (Univ. Montpellier 2 (France). Lab. de Physicochimie des Materiaux Solides)

    1994-06-01

    High pressure self-propagating high-temperature synthesis (SHS) between nickel and aluminum powders (mixed in NiAl stoichiometry) is used for the synthesis of the intermetallic compound NiAl and NiAl-AlN composites. It is shown that the nature of the products is influenced by the morphology of the starting powders, the heating rate of the reaction and the nature of the pressure gas. This paper explains the effect of various material and processing parameters on the final sintered density. The products of combustion were examined by using DTA analysis, X-ray diffraction, scanning electron microscopy and hardness tests.

  6. Process for synthesizing compounds from elemental powders and product

    DOEpatents

    Rabin, B.H.; Wright, R.N.

    1993-12-14

    A process for synthesizing intermetallic compounds from elemental powders is described. The elemental powders are initially combined in a ratio which approximates the stoichiometric composition of the intermetallic compound. The mixed powders are then formed into a compact which is heat treated at a controlled rate of heating such that an exothermic reaction between the elements is initiated. The heat treatment may be performed under controlled conditions ranging from a vacuum (pressureless sintering) to compression (hot pressing) to produce a desired densification of the intermetallic compound. In a preferred form of the invention, elemental powders of Fe and Al are combined to form aluminide compounds of Fe[sub 3] Al and FeAl. 25 figures.

  7. Saturation fluorimetry of complex organic compounds with a high local concentration of fluorophores (by the example of phytoplankton)

    SciTech Connect

    Maslov, D V; Ostroumov, E E; Fadeev, V V [Department of Physics, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

    2006-02-28

    Saturation of fluorescence of complex organic compounds with a high local concentration of fluorescing molecules (fluorophores), when singlet-singlet annihilation makes a noticeable contribution to saturation, is considered. The fluorescence saturation curve is obtained analytically for the case of a rectangular temporal and spatial distribution of photons in a laser pulse. It is shown that the fluorescence saturation curve depends on the parameter {Phi}{sub 0}, which is proportional to the concentration of fluorescing molecules, and on the parameters A, B, and {alpha} describing the influence of singlet-singlet annihilation, bleaching of an optically thin layer, and nonstationarity of excitation, respectively. The fluorescence saturation curves are studied experimentally for compounds with a high local concentration of fluorescing molecules such as molecules of a monoculture of diatomic alga Thalassiosira weissflogii. The experimental fluorescence saturation curves are well described by the obtained analytic expression. The values of the parameter {Phi}{sub 0}, proportional to the concentration of chlorophyll a, and the parameter A (for the first time) are obtained from the alga fluorescence saturation curves. (laser applications and other topics in quantum electronics)

  8. Structural transitions in RNi(10)Si(2) intermetallics.

    PubMed

    Moze, O; Kockelmann, W A; Hofmann, M; Cadogan, J M; Ryan, D H; Buschow, K H J

    2009-03-25

    Intermetallic compounds of the type RFe(10)Si(2) and RCo(10)Si(2) crystallize in the ThMn(12) structure (space group I4/mmm) whilst the heavy rare earth series RNi(10)Si(2) crystallize in a maximal subgroup of I4/mmm, P4/nmm. Reported here are neutron powder diffraction investigations for TbNi(10)Si(2) and ErNi(10)Si(2) which show that the P4/nmm structure undergoes a high temperature order-disorder phase transition at approximately 930?°C above which the ordered Ni and Si fractions revert to a random distribution on 4d and 4e sites. The volume expansion has been tracked in detail via the temperature dependence of the lattice parameters, whilst the temperature dependence of the thermal expansion coefficients ?(11), ?(33) and ?(volume) has been determined from the lattice parameters. Associated with the order-disorder transition is a transition associated with a displacement of the R ion along the c-axis. Both transitions are of second order and the critical exponent associated with the order-disorder and displacive transitions, ? = 0.31, is in excellent agreement with the exponent determined for the three-dimensional Ising model. PMID:21817452

  9. Complex of titanocene with tolan as a catalyst for the homogeneous hydrogenation of unsaturated compounds

    SciTech Connect

    Shur, V.B.; Burlakov, V.V.; Vol'pin, M.E.

    1986-09-01

    The complex of titanocene with tolan (Cp/sub 2/Ti(C/sub 2/Ph/sub 2/)) (I) synthesized by the reaction of Cp/sub 2/TiCl/sub 2/ with magnesium and tolan in THF was found to be an effective catalyst for the homogeneous hydrogenation of olefins and acetylenes at 20 C atmospheric hydrogen pressure. The reaction was carried out with a substrate. Under the conditions of the experiment, tolan as well as cis- and trans-stilbenes are hydrogenated virtually quantitatively in a few minutes to dibenzyl. Similarly, styrene is converted to ethylbenzene, 3-hexyne is converted to hexane, 1-heptene is converted to heptane, cyclohexene is converted to cyclohexane, and trans, trans-1,4-diphenyl-1,3-butadiene is converted to 1,4-diphenylbutane. The authors' attempts to synthesize (Cp/sub 2/Ti(C/sub 2/Ph/sub 2/)) with tolan were unsucessful.

  10. Photodissociation dynamics of organometallic compounds: Study of the dihydride complex H2Fe(CO)4

    SciTech Connect

    Heitz, M. C.; Daniel, C. [Laboratoire de Chimie Quantique UPR139 du CNRS Universite Louis Pasteur, Institut Le Bel 4, rue Blaise Pascal, 67000 Strasbourg (France)

    1996-04-01

    The photodissociation of the dihydride complex H2Fe(CO)4 has been investigated by a theoretical approach, involving time-dependent wave packet propagations on potential energy surfaces (PES) obtained from CASSCF-MRCI calculations. A two dimensions simulation is proposed, allowing the study of two concurrents processes, namely photoinduced elimination of molecular hydrogen vs loss of a carbonyl ligand. Three singlet excited states {sup 1}bA1(x{sup 2}-y{sup 2}{yields}{sigma}g*), {sup 1}aB2(x{sup 2}-y{sup 2}{yields}{sigma}u*), {sup 1}aB1(yz{yields}{sigma}g*) has been identified in the range of energy corresponding to the experimental absorption spectrum. Wave packets propagations performed separately on the three PES describe the elementary processes contributing to the photochemical behavior of the molecule. The absorption spectrum reflecting these different processes, has been calculated, using the time dependent formalism.

  11. Electronic and optical properties of RESn3 (RE=Pr & Nd) intermetallics: A first principles study

    NASA Astrophysics Data System (ADS)

    Pagare, G.; Abraham, Jisha A.; Sanyal, S. P.

    2015-06-01

    A theoretical study of structural, electronic and optical properties of RESn3 (RE = Pr & Nd) intermetallics have been investigated systematically using first principles density functional theory. The calculations are carried out within the PBE-GGA and LSDA for the exchange correlation potential. The ground state properties such as lattice parameter (a0), bulk modulus (B) and its pressure derivative (B') are calculated and the calculated lattice parameters show well agreement with the experimental results. We first time predict elastic constants for these compounds. From energy dispersion curves, it is found that these compounds are metallic in nature. The linear optical response of these compounds are also studied and the higher value of static dielectric constant shows the possibility to use them as good dielectric materials.

  12. Theoretical study of model compound I complexes of horseradish peroxidase and catalase.

    PubMed Central

    Du, P; Loew, G H

    1995-01-01

    Theoretical studies of the electronic structure and spectra of models for the ferric resting state and Compound I intermediates of horseradish peroxidase (HRP-I) and catalase (CAT-I) have been performed using the INDO-RHF/CI method. The goals of these studies were twofold: i) to determine whether the axial ligand of HRP is best described as imidazole or imidazolate, and ii) to address the long-standing question of whether HRP-I and CAT-I are a1u and a2u tau cation radicals. Only the imidazolate HRP-I model led to a calculated electronic spectra consistent with the experimentally observed significant reduction in the intensity of the Soret band compared with the ferric resting state. These results provide compelling evidence for significant proton transfer to the conserved Asp residue by the proximal histidine. The origin of the observed reduction of the Soret band intensity in HRP-I and CAT-I spectra has been examined and found to be caused by the mixing of charge transfer transitions into the predominantly porphyrin tau-tau transitions. For both HRP-I and CAT-I, the a1u porphyrin tau cation state is the lowest energy, and it is further stabilized by both the anionic form of the ligand and the porphyrin ring substituents of protoporphyrin-IX. The calculated values of quadrupole-splitting observed in the Mossbauer resonance of HRP-I and CAT-I are similar for the a1u and a2u tau cation radicals. Electronic spectrum of the a1u tau cation radical of HRP-I are more similar to the observed spectra, whereas the spectra of both a1u tau and a2u tau cation radicals of CAT-I resemble the observed spectra. These results also indicate the limitations of using any one observable property to try to distinguish between these states. Taken together, comparison of calculated and observed properties indicate that there is no compelling reason to invoke the higher energy a2u tau cation radical as the favored state in HRP-I and CAT-I. Both ground-state properties and electronic spectra are consistent with the a1u tau cation radical. PMID:7711270

  13. Tracer aroma compound transfer from a solid and complex-flavored food matrix packed in treated papers or plastic packaging film.

    PubMed

    Dury-Brun, Cécile; Lequin, Sonia; Chalier, Pascale; Desobry, Stéphane; Voilley, Andrée

    2007-02-21

    The objective of this work was to study the transfer of four aroma compounds (ethyl butyrate, ethyl hexanoate, cis-3-hexenol, and benzaldehyde) from a solid and complex-flavored food matrix (sponge cake) toward and through packaging films placed in indirect contact during storage in accelerated aging conditions (38 degrees C and 86% relative humidity gradient). The efficiency of treated papers relative to that of standard paper and plastic as barrier was tested. Before storage, aroma compound volatility in the sponge cake was measured, and similar values were found between aroma compounds, due to the fat content of the sponge cake. Whatever the aroma compound, permeability values during storage were similar for the same packaging film. The plastic film was the highest barrier, whereas calendering and coating treatments applied to treated papers decreased effectively their permeability. An opposite trend was observed for aroma compound sorption into packaging films during storage. PMID:17263545

  14. Dislocations in Complex Materials

    SciTech Connect

    Chisholm, Matthew F [ORNL; Kumar, K. S. [Brown University; Hazzledine, P. M. [UES, Incorporated, Dayton, OH

    2005-01-01

    Deformation of metals and alloys by dislocations gliding between well-separated slip planes is a well-understood process, but most crystal structures do not possess such simple geometric arrangements. Examples are the Laves phases, the most common class of intermetallic compounds and exist with ordered cubic, hexagonal, and rhombohedral structures. These compounds are usually brittle at low temperatures, and transformation from one structure to another is slow. On the basis of geometric and energetic considerations, a dislocation-based mechanism consisting of two shears in different directions on adjacent atomic planes has been used to explain both deformation and phase transformations in this class of materials. We report direct observations made by Z-contrast atomic resolution microscopy of stacking faults and dislocation cores in the Laves phase Cr{sub 2}Hf. These results show that this complex dislocation scheme does indeed operate in this material. Knowledge gained of the dislocation core structure will enable improved understanding of deformation mechanisms and phase transformation kinetics in this and other complex structures.

  15. Titanium aluminide intermetallic alloys with improved wear resistance

    DOEpatents

    Qu, Jun; Lin, Hua-Tay; Blau, Peter J.; Sikka, Vinod K.

    2014-07-08

    The invention is directed to a method for producing a titanium aluminide intermetallic alloy composition having an improved wear resistance, the method comprising heating a titanium aluminide intermetallic alloy material in an oxygen-containing environment at a temperature and for a time sufficient to produce a top oxide layer and underlying oxygen-diffused layer, followed by removal of the top oxide layer such that the oxygen-diffused layer is exposed. The invention is also directed to the resulting oxygen-diffused titanium aluminide intermetallic alloy, as well as mechanical components or devices containing the improved alloy composition.

  16. Characteristics of odorous carbonyl compounds in the ambient air around a fishery industrial complex of Yeosu, Korea.

    PubMed

    Ma, Zhongkun; Jeon, Junmin; Kim, Sangchai; Jung, Sangchul; Lee, Woobum; Seo, Seonggyu

    2012-01-01

    In this study, the amounts of odorous carbonyl compounds (OCCs) including acetaldehyde (Acet-A), propionaldehyde (Pron-A), butylaldehyde (Buty-A), iso-valeric aldehyde (Iso-Vale-A) and n-valeric aldehyde (N-Vale-A) emitted from a fishery industrial complex near the exhibition facilities of "Expo 2012 Yeosu Korea" were measured. Acet-A was found to be the most abundant OCC, and the total concentrations of the OCCs were the highest in the summer. However, due to vehicular exhaust and photochemical reactions, the concentrations of some of the OCCs presented their highest levels in the fall. A significant correlation between Acet-A and Buty-A was found at the major fishery facilities (r = 0.816, p = 1.87E-15, n = 60) and at the border areas (r = 0.809, p = 3.40E-12, n = 48) of this fishery industrial complex. The concentrations of OCCs at the border areas were not worse than those at the urban areas in other places, indicating that the concentrations of ambient OCCs at the border areas were not greatly influenced by manmade activities. PMID:23520848

  17. Cohesive properties and vibrational entropy of 3d transition-metal compounds: MX (NaCl) compounds (X=C, N, O, S), complex carbides, and nitrides

    Microsoft Academic Search

    Armando Fernández Guillermet; Göran Grimvall

    1989-01-01

    We let compounds between a 3d transition metal (M) and a nonmetal X (X=C,N,O,S) be characterized by three parameters: the average number of valence electrons per atom (ne), the average volume per atom (Omega), and the logarithmically averaged atomic mass (Meff). Three quantities with the dimension of energy are then considered: the cohesive energy Ecoh of the compound, its enthalpy

  18. Machinability of a nickel aluminide intermetallic alloy

    SciTech Connect

    Chatterjee, S. (Univ. of Tennessee, Knoxville (United States))

    1993-02-01

    This article reports the results of an experimental study on the machinability of a nickel aluminide intermetallic alloy. Machining was conducted at various speeds, and results indicate low material removal rates. Chips collected for each test run were measured for thickness for shear angle calculation and were subsequently observed microscopically. Chip segmentation was observed microscopically, and a fluctuation in the shear angle was evidenced. A parameter characterizing the severity of the machining process, the chip reduction coefficient (K), was calculated from chip thickness measurements. The calculated values of K were found to be low, indicating a low severity of the metalcutting process. This, however, is in contract with the observed low rates of metal removal and low tool life. Thus, conventional metalcutting characterization parameters require re-examining in terms of machining high-strength materials.

  19. Aqueous Corrosion Behavior of Iron aluminide Intermetallics

    NASA Astrophysics Data System (ADS)

    Sharma, Garima; Singh, P. R.; Sharma, R. K.; Gaonkar, K. B.; Ramanujan, R. V.

    2007-12-01

    Iron aluminide intermetallics based on DO3 ordered structure are being developed for use as structural materials and cladding material for conventional engineering alloys. Aqueous corrosion behavior of iron aluminides has been studied extensively by electrochemical techniques. Studies were carried out on pure Fe (99.9%), Fe-28Al (at.%), Fe-28Al-3Cr (at.%), and AISI SS 304 so as to compare and contrast their behavior in same experimental condition. Polarization behavior under different pH conditions was examined to evaluate their performance in acidic, basic, and neutral solutions. Pitting behavior was also studied in solution containing Cl-1 ions. The stability of the passive film formed was studied by current time transients and potential decay profiles. The presence of 3 at.% Cr in iron aluminides was found to improve the aqueous corrosion resistance and makes it comparable to AISI SS 304.

  20. Thermophysical properties of U 2Mo intermetallic

    NASA Astrophysics Data System (ADS)

    Kutty, T. R. G.; Dash, Smruti; Banerjee, Joydipta; Kaity, Santu; Kumar, Arun; Basak, C. B.

    2012-01-01

    The current paper has investigated specific heat capacity, coefficient of thermal expansion and phase transition temperatures of U 2Mo intermetallic. The transformation of U 2Mo phase to bcc (?-uranium) phase occurred at 853 K. The coefficient of thermal expansion has been determined in the temperature range 423-873 K to be 14.65 × 10 -6 K -1. The specific heat data showed a smooth curve up to 773 K and above it a change in trend to follow a ?-shape was observed. The specific heat values of U 2Mo have been found to be lower than that calculated from the additivity rule. This study provides first time data on U 2Mo. The data obtained from this investigation were compared to available literature on U-Mo alloys.

  1. An Investigation into the evolution of damage and residual stresses in Ti6Al4V-Al?Ti metal intermetallic laminate (MIL) composites

    E-print Network

    Li, Tiezheng

    2006-01-01

    S. , Noda, T. , Structural Intermetallics, The Minerals,K. , Dahms, M. , Structural Intermetallics, The Minerals,structural and aerospace applications. Chapter 2 reviews the background of intermetallics

  2. Thermomechanical processing of plasma sprayed intermetallic sheets

    DOEpatents

    Hajaligol, Mohammad R. (Midlothian, VA); Scorey, Clive (Cheshire, CT); Sikka, Vinod K. (Oak Ridge, TN); Deevi, Seetharama C. (Midlothian, VA); Fleischhauer, Grier (Midlothian, VA); Lilly, Jr., A. Clifton (Chesterfield, VA); German, Randall M. (State College, PA)

    2001-01-01

    A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3% Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

  3. NMR Solution Structure of the Catalytic Fragment of Human Fibroblast Collagenase Complexed with a Sulfonamide Derivative of a Hydroxamic Acid Compound

    Microsoft Academic Search

    Franklin J. Moy; Pranab K. Chanda; James M. Chen; Scott Cosmi; Wade Edris; Jerauld S. Skotnicki; Jim Wilhelm; Robert Powers

    1999-01-01

    The solution structure of the catalytic fragment of human fibroblast collagenase (MMP-1) complexed with a sulfonamide derivative of a hydroxamic acid compound (CGS-27023A) has been determined using two-dimensional and three-dimensional heteronuclear NMR spectroscopy. The solution structure of the complex was calculated by means of hybrid distance geometry-simulated annealing using a combination of experimental NMR restraints obtained from the previous refinement

  4. On the intermetallic corrosion of Cu-Al wire bonds

    Microsoft Academic Search

    Tim Boettcher; Michael Rother; Stefan Liedtke; Mandy Ullrich; Marc Bollmann; Andreas Pinkernelle; Daniel Gruber; H.-J. Funke; M. Kaiser; Kan Lee; M. Li; K. Leung; T. Li; M. L. Farrugia; O. O'Halloran; M. Petzold; B. Ma?rz; R. Klengel

    2010-01-01

    A detailed description of the Cu-Al wire bond interface is presented, which can possibly explain the often observed corrosion failures in humidity reliability tests. Using micro-structural analysis techniques, it is shown that the unstressed interface contains up to three intermetallic phases, where the Cu-rich phases are located at the Cu-ball interface. Upon humidity stress test only the high-Cu containing intermetallic

  5. Formation of intermetallics in lead-free systems

    Microsoft Academic Search

    M. Braunovic; D. Gagnon

    2004-01-01

    Formation and growth of intermetallics are one of the most important problem in the search for reliable lead-free alloys. Since the majority of the commercially available lead-free alloys contain high tin concentration, there is a long-term reliability concern due to tendency of tin to form intermetallics. A prolonged exposure to higher temperatures of lead-free alloys results in the continuous growth

  6. Reaction time and rapid serial processing measures of information processing speed in multiple sclerosis: complexity, compounding, and augmentation.

    PubMed

    Hughes, Abbey J; Denney, Douglas R; Lynch, Sharon G

    2011-11-01

    Information processing speed is frequently cited as the primary cognitive domain impacted by multiple sclerosis (MS) and is usually evaluated with reaction time (RT) or rapid serial processing (RSP) measures. The present study compared the efficacy of RT and RSP measures to distinguish between patients with MS (N = 42) and healthy controls (N = 40). The RT measure was patterned after the Computerized Tests of Information Processing and included measures of simple, choice, and semantic RT. The RSP measures consisted of the Symbol Digit Modalities Test (SDMT) and the Stroop Test. Substantial differences in information processing speed between patients and controls were found on all tests, with slightly larger effect sizes for RSP measures than RT measures and for the SDMT than the Stroop Test. Binary logistic regression analyses showed RSP measures performed better than RT measures at distinguishing patients from controls, and likewise, the SDMT score performed better than the scores derived from the Stroop Test. Results are discussed in the context of three effects associated with common measures of processing speed: complexity, compounding, and augmentation. PMID:22040901

  7. Dispersion and photochemical oxidation of reduced sulfur compounds in and around a large industrial complex in Korea

    NASA Astrophysics Data System (ADS)

    Song, Sang-Keun; Shon, Zang-Ho; Kim, Ki-Hyun; Kim, Yoo-Keun; Pal, Raktim

    In this study, the environmental behavior of reduced sulfur compounds (RSCs: H 2S, DMS, CS 2, DMDS, and CH 3SH) was investigated in an area influenced by strong anthropogenic processes based on a numerical modeling approach. The RSC emission concentrations were measured from multiple locations around the Ban-Wall industrial complex (BWIC) in the city of An San (AS), Korea, during a series of field campaigns held between August 2004 and September 2005. These emissions were then used as input for a CALPUFF dispersion model with the 34 dominant chemical reactions for RSCs. The impact of RSC emission on SO 2 concentrations was assessed further in the study areas. The model study indicated the possibility that RSCs emitted in and around the BWIC can exert a direct impact on the ambient SO 2 concentration levels in its surrounding areas with the most prominent effect observed during summer. Our prediction indicated that a significant fraction of SO 2 was produced photochemically in and around the BWIC during the summer (about 30% of total SO 2 concentrations) and fall events (˜20%). These photochemical productions of SO 2 were mainly ascribable to H 2S (˜60% of total contributions) and DMDS (˜25%) out of all five target RSCs. Meteorological contribution (dispersion) to SO 2 concentration level was also highest during summer.

  8. Multiconfigurational nature of 5f orbitals in uranium and plutonium intermetallics

    PubMed Central

    Booth, C.H.; Jiang, Yu; Wang, D.L.; Mitchell, J.N.; Tobash, P.H.; Bauer, E.D.; Wall, M.A.; Allen, P.G.; Sokaras, D.; Nordlund, D.; Weng, T.-C.; Torrez, M.A.; Sarrao, J.L.

    2012-01-01

    Uranium and plutonium’s 5f electrons are tenuously poised between strongly bonding with ligand spd-states and residing close to the nucleus. The unusual properties of these elements and their compounds (e.g., the six different allotropes of elemental plutonium) are widely believed to depend on the related attributes of f-orbital occupancy and delocalization for which a quantitative measure is lacking. By employing resonant X-ray emission spectroscopy (RXES) and X-ray absorption near-edge structure (XANES) spectroscopy and making comparisons to specific heat measurements, we demonstrate the presence of multiconfigurational f-orbital states in the actinide elements U and Pu and in a wide range of uranium and plutonium intermetallic compounds. These results provide a robust experimental basis for a new framework toward understanding the strongly-correlated behavior of actinide materials. PMID:22706643

  9. Transient liquid phase bonding of intermetallics

    NASA Astrophysics Data System (ADS)

    Guan, Yimin

    The present work was undertaken to examine the applicability of transient liquid phase bonding to structural intermetallics. This research was based on an investigation of the mechanisms governing microstructural development in the joint and adjacent substrates during the joining process. The bonding systems investigated included polycrystalline NiAl/Cu/Ni, polycrystalline NiAl/Cu/superalloys (Martin-Marietta (MM)-247, Inconel (IN) 718 and Nimonic 90), single-crystal NiAl (with 1.5 at % Hf) joined to MM-247 using different filler metals (Cu foil, powder filler metal and electro-plated thin Cu film), and martensitic NiAl joined with martensitic NiTi using Cu foil and specially designed powder filler metals. In polycrystalline NiAl/Cu/Ni bonds, the mechanism of isothermal solidification is considered. Changes in the microstructure of the bond centerline due to element redistribution are discussed. The precipitation of both L1sb2 type gammasp' and B2 type beta phase at the joint centerline is investigated. The formation of martensitic L1sb0 type NiAl is also examined. The mechanical properties of the joints are investigated using shear strength and microhardness tests. In TLP bonding of polycrystalline NiAl with MM-247, both the epitaxial growth of the beta phase NiAl into the joint and the formation of non-epitaxial beta-phase layers are considered. The formation of second-phases, including the gammasp' phase, carbides, and sigma-phase intermetallics is also examined. Bond-line and adjacent substrate microstructures for the NiAl/Cu/MM-247 bonds are correlated with joint mechanical properties determined by room temperature shear testing. Single-crystal NiAl (1.5 at % Hf)/Cu/MM-247 joints are examined and compared with polycrystalline NiAl/Cu/MM247 joints. The effect of Hf on the microstructure of joints is investigated. The influence of different filler metals (i.e., wide-gap powder filler metal and electro-plated thin film filler metal) on the joining process is also considered. In TLP bonding of martensitic NiAl with martensitic NiTi, the formation Ti depletion region was observed while using Cu foil as the filler metal. Alternative filler metals were successfully used to solve this problem. According to the experimental results, standard TLP bonding models cannot be applied to the bonding systems in this research. The influence of second phase formation on TLP models is discussed.

  10. Thermal stress effects in intermetallic matrix composites

    NASA Astrophysics Data System (ADS)

    Wright, P. K.; Sensmeier, M. D.; Kupperman, D. S.; Wadley, H. N. G.

    1993-09-01

    Intermetallic matrix composites develop residual stresses from the large thermal expansion mismatch (delta-alpha) between the fibers and matrix. This work was undertaken to: establish improved techniques to measure these thermal stresses in IMC's; determine residual stresses in a variety of IMC systems by experiments and modeling; and, determine the effect of residual stresses on selected mechanical properties of an IMC. X ray diffraction (XRD), neutron diffraction (ND), synchrotron XRD (SXRD), and ultrasonics (US) techniques for measuring thermal stresses in IMC were examined and ND was selected as the most promising technique. ND was demonstrated on a variety of IMC systems encompassing Ti- and Ni-base matrices, SiC, W, and Al2O3 fibers, and different fiber fractions (Vf). Experimental results on these systems agreed with predictions of a concentric cylinder model. In SiC/Ti-base systems, little yielding was found and stresses were controlled primarily by delta-alpha and Vf. In Ni-base matrix systems, yield strength of the matrix and Vf controlled stress levels. The longitudinal residual stresses in SCS-6/Ti-24Al-llNb composite were modified by thermomechanical processing. Increasing residual stress decreased ultimate tensile strength in agreement with model predictions. Fiber pushout strength showed an unexpected inverse correlation with residual stress. In-plane shear yield strength showed no dependence on residual stress. Higher levels of residual tension led to higher fatigue crack growth rates, as suggested by matrix mean stress effects.

  11. Bulk and defect properties of ordered intermetallics

    SciTech Connect

    Fu, C.L.; Yoo, M.H.

    1993-12-31

    First-principles calculations based on the local-density-functional theory have been used to investigate the factors governing strength of ordered intermetallic alloys. Unlike Ni{sub 3}Al, calculated elastic constants and shear fault energies indicate anomalous yield strength behavior is not likely to occur in Ni{sub 3}Si. This suggests the inadequacy of cross-slip-pinning model to explain the strength anomaly in the L1{sub 2} structure. For strongly ordered NiAl, the defect structure is dominated by two types of defects -- monovacancies on the Ni sites and substitutional antisite defects on the Al sites. By contrast, for Ni{sub 3}Al, absence of structural vacancies and deviations from stoichiometry are accommodated by substitutional antisite defects on both sublattices. Intrinsic strengthening mechanisms in TiAl are discussed in terms of calculated elastic constants and shear fault energies. Because of reduced fault energies at the {gamma}/{alpha}{sub 2} interface, slip and twinning contribute significantly to high shear deformation of the lamellar structure.

  12. SCB ignition of pyrotechnics, thermites and intermetallics

    SciTech Connect

    Bickes, R.W. Jr.; Grubelich, M.C.

    1996-09-01

    We investigated ignition of pyrotechnics, metal-fuel/metal-oxide compositions (thermites), and exothermic alloy compositions (intermetallics) using a semiconductor bridge (SCB). It was shown that these materials could be ignited at low energy levels with an appropriately designed SCB, proper loading density, and good thermal isolation. Materials tested included Al/CuO, B/BaCrO{sub 4}, TiH{sub 1.65}/KClO{sub 4}, Ti/KClO{sub 4}, Zr/BaCrO{sub 4}, Zr/CuO, Zr/Fe{sub 2}O{sub 3}, Zr/KClO{sub 4}, and 100-mesh Al/Pd. Firing set was a capacitor discharge unit with charge capacitors ranging from 3 to 20,000 {mu}F at charge voltages 5-50 V. Devices functioned a few miliseconds after onset of current pulse at input energies as low as 3 mJ. We also report on a thermite torch design.

  13. Ground state searches in fcc intermetallics

    SciTech Connect

    Wolverton, C.; de Fontaine, D. (Lawrence Berkeley Lab., CA (United States)); Ceder, G. (Massachusetts Inst. of Tech., Cambridge, MA (United States)); Dreysse, H. (Nancy-1 Univ., 54 (France). Lab. de Physique du Solide)

    1991-12-01

    A cluster expansion is used to predict the fcc ground states, i.e., the stable phases at zero Kelvin as a function of composition, for alloy systems. The intermetallic structures are not assumed, but derived regorously by minimizing the configurational energy subject to linear constraints. This ground state search includes pair and multiplet interactions which spatially extend to fourth nearest neighbor. A large number of these concentration-independent interactions are computed by the method of direct configurational averaging using a linearized-muffin-tin orbital Hamiltonian cast into tight binding form (TB-LMTO). The interactions, derived without the use of any adjustable or experimentally obtained parameters, are compared to those calculated via the generalized perturbation method extention of the coherent potential approximation within the context of a KKR Hamiltonian (KKR-CPA-GPM). Agreement with the KKR-CPA-GPM results is quite excellent, as is the comparison of the ground state results with the fcc-based portions of the experimentally-determined phase diagrams under consideration.

  14. Fatigue crack growth in niobium aluminide intermetallics

    SciTech Connect

    Dipasquale, J.; Gahutu, D.; Soboyejo, W. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering; Konitzer, D. [General Electric Aircraft Engines, Cincinnati, OH (United States)

    1995-07-01

    The results of a recent study of the fatigue crack growth in a new class of niobium aluminide (Nb{sub 3}Al) intermetallics alloyed with various levels of Ti are presented. The alloys studied have the following nominal compositions (note that all compositions are quoted in atomic %): Nb-15Al-10Ti(10Ti alloy), Nb 15Al-25Ti(25Ti alloy), Nb 15Al-40Ti(40Ti alloy) and Nb 12.5Al-41Ti-1.5Mo(41Ti alloy). Fatigue crack growth behavior was studied at room-temperature in all the alloys. Fracture mechanisms were determined by inspection of SEM images of fracture surfaces. Faceted cleavage fracture modes were apparent on the 10Ti and 25Ti alloys. The 40Ti and 41Ti alloys exhibited clear evidence of ductile dimpled fracture. The ductile 40Ti and 41Ti alloys are shown to have comparable or better fatigue crack growth resistance than mill annealed Ti-6Al-4V. The effects of crack orientation (relative to elongated grains) on the fatigue crack growth behavior of the 41Ti alloy are also discussed.

  15. Crystal Structure, Chemical Bonding and Magnetism Studies for Three Quinary Polar Intermetallic Compounds in the (Eu1?xCax)9In8(Ge1?ySny)8 (x = 0.66, y = 0.03) and the (Eu1?xCax)3In(Ge3?ySn1+y) (x = 0.66, 0.68; y = 0.13, 0.27) Phases

    PubMed Central

    Woo, Hyein; Jang, Eunyoung; Kim, Jin; Lee, Yunho; Kim, Jongsik; You, Tae-Soo

    2015-01-01

    Three quinary polar intermetallic compounds in the (Eu1?xCax)9In8(Ge1?ySny)8 (x = 0.66, y = 0.03) and the (Eu1?xCax)3In(Ge3-ySn1+y) (x = 0.66, 0.68; y = 0.13, 0.27) phases have been synthesized using the molten In-metal flux method, and the crystal structures are characterized by powder and single-crystal X-ray diffractions. Two orthorhombic structural types can be viewed as an assembly of polyanionic frameworks consisting of the In(Ge/Sn)4 tetrahedral chains, the bridging Ge2 dimers, either the annulene-like “12-membered rings” for the (Eu1?xCax)9In8(Ge1?ySny)8 series or the cis-trans Ge/Sn-chains for the (Eu1?xCax)3In(Ge3?ySn1+y) series, and several Eu/Ca-mixed cations. The most noticeable difference between two structural types is the amount and the location of the Sn-substitution for Ge: only a partial substitution (11%) occurs at the In(Ge/Sn)4 tetrahedron in the (Eu1?xCax)9In8(Ge1?ySny)8 series, whereas both a complete and a partial substitution (up to 27%) are observed, respectively, at the cis-trans Ge/Sn-chain and at the In(Ge/Sn)4 tetrahedron in the (Eu1?xCax)3In(Ge3?ySn1+y) series. A series of tight-binding linear muffin-tin orbital calculations is conducted to understand overall electronic structures and chemical bonding among components. Magnetic susceptibility measurement indicates a ferromagnetic ordering of Eu atoms below 5 K for Eu1.02(1)Ca1.98InGe2.87(1)Sn1.13. PMID:25913380

  16. Non-covalent interactions of nitrous oxide with aromatic compounds: Spectroscopic and computational evidence for the formation of 1:1 complexes

    NASA Astrophysics Data System (ADS)

    Cao, Qian; Gor, Gennady Y.; Krogh-Jespersen, Karsten; Khriachtchev, Leonid

    2014-04-01

    We present the first study of intermolecular interactions between nitrous oxide (N2O) and three representative aromatic compounds (ACs): phenol, cresol, and toluene. The infrared spectroscopic experiments were performed in a Ne matrix and were supported by high-level quantum chemical calculations. Comparisons of the calculated and experimental vibrational spectra provide direct identification and characterization of the 1:1 N2O-AC complexes. Our results show that N2O is capable of forming non-covalently bonded complexes with ACs. Complex formation is dominated by dispersion forces, and the interaction energies are relatively low (about -3 kcal mol-1); however, the complexes are clearly detected by frequency shifts of the characteristic bands. These results suggest that N2O can be bound to the amino-acid residues tyrosine or phenylalanine in the form of ? complexes.

  17. Uptake and fate of phenol and aniline in rainbow trout and daphnids during single-compound and complex-mixture exposures

    SciTech Connect

    Dauble, D.D.; Riley, R.G.; Bean, R.M.; Lusty, E.W.; Hanf, R.W. Jr.

    1984-10-01

    Studies were conducted of the potential for uptake and mobilization of phenol and aniline when presented as single compounds to the biouptake of these compounds within a complex water-soluble fraction (WSF) of a coal liquid. Estimated bioconcentration factors (BCF) of phenol-only exposures differed from BCFs obtained in the presence of the WSF. Differences in uptake could be due to competitive interactions among similar molecules for uptake and absorption, since phenolic compounds comprised nearly 90% of the soluble components in the complex mixture. Observed differences in unextractable /sup 14/C residues suggested selective binding of phenol or metabolites to trout tissue storage sites. Differences in potential for bioaccumulation of phenol in complex mixtures were not consistent with estimates of BCF as determined by measured octanol/water coefficient values. In contrast to phenol, presence of coal-liquid water solubles did not significantly influence either the uptake or elimination of /sup 14/C aniline by daphnids or trout. Identification of metabolites would provide useful information on potential differences in biotransformation and elimination mechanisms in complex organic mixtures. 15 references, 2 figures, 6 tables.

  18. Polyoxometalate-based organic-inorganic hybrid compounds containing transition metal mixed-organic-ligand complexes of N-containing and pyridinecarboxylate ligands.

    PubMed

    Zhao, De-Chuan; Hu, Yang-Yang; Ding, Hong; Guo, Hai-Yang; Cui, Xiao-Bing; Zhang, Xiao; Huo, Qi-Sheng; Xu, Ji-Qing

    2015-05-01

    Five new organic-inorganic hybrid compounds based on the Keggin-type polyoxoanion [SiW12O40](4-), namely [Cu3(2,2'-bpy)3(inic)(?2-OH)(H2O)][SiW12O40]·2H2O (), [Cu6(phen)6(?3-Cl)2(?2-Cl)2Cl2(inic)2][SiW12O40]·6H2O (), [Cu2(hnic)(2,2'-bpy)2Cl]2[H2SiW12O40] (), [Cu2(nic)(phen)2Cl2]2[SiW12O40] () and [Cu2(pic)(2,2'-bpy)2Cl]2[SiW12O40] () (inic = isonicotinic acid, hnic = 2-hydroxy-nicotinic acid, nic = nicotinic acid, pic = picolinic acid, 2,2'-bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline) have been synthesized and characterized by IR, UV-Vis, XPS, XRD, cyclic voltammetric measurements, photoluminescence analysis and single crystal X-ray diffraction analysis. Crystal analysis reveals that compound exhibits a 2-D double layered framework structure constructed from [SiW12O40](4-) and copper-aqua-2,2'-bipy-hydroxyl-isonicotinate complexes. Compound is a 0-D discrete structure formed by [SiW12O40](4-) and copper-chloro-isonicotinate-phenanthroline complexes. Compound shows a 1-D single chain structure based on the linkage of copper-2,2-bpy-chloro-2-hydroxy-nicotinate complexes and [SiW12O40](4-). Compounds and both contain polyoxometalate supported transition metal complexes, one is a polyoxometalate supported copper-chloro-nicotinate-phenanthroline complex in , and the other is a polyoxometalate supported copper-2,2-bpy-chloro-nicotinate complex in . It should be noted that nicotinic, isonicotinic and picolinic acids are structural isomers and 2-hydroxy-nicotinic acid is an in situ hydroxylated product of nicotinic acid. In addition, photocatalytic degradation of Rhodamine B (RhB) by compounds has been investigated in aqueous solutions. PMID:25882351

  19. Strength and ductility of L1{sub 2}-based intermetallics. Final report

    SciTech Connect

    Schulson, E. M.

    2002-01-18

    For the first time a complete and systematic study has been made of the strength and ductility of the L1{sub 2}-based intermetallic compounds Ni{sub 3}X (X=Al,Ga,Ge,Ga), w/wo boron and w/wo notches. Variables included grain size, boron concentration, deviation from stoichiometry, temperature, strain rate, and notch geometry. Approaches included tensile, compression, hardness and Bauchinger tests; optical microscopy; scanning, transmission and high-resolution scanning-transmission electron microscopy; and numerical modeling. The hypothesis tested was that the increase in ductility induced by boron is caused largely by an increase in the accommodation of slip at grain boundaries. The results and interpretations were published in 41 papers. Every result obtained over the course of the study is consistent with this hypothesis. Indeed, every result obtained by other investigators on the same alloy systems is also consistent with the hypothesis. Thus, we conclude the study by saying that the grain boundary accommodation of slip is a major factor in accounting for the beneficial effect of boron on the strength and ductility of Ni{sub 3}X-based L1{sub 2} intermetallics.

  20. Intermetallic growth and mechanical behavior of low and high melting temperature solder alloys

    Microsoft Academic Search

    D. R. Frear; P. T. Vianco

    1994-01-01

    The presence of an intermetallic is often an indication of good wetting in a solder joint. However, excessive intermetallic\\u000a growth and the brittleness of the intermetallic layer may be detrimental to joint reliability. This study examined the growth\\u000a and mechanical behavior of interfacial intermetallics between copper and six solder alloys commonly used in electronics assembly.\\u000a The solder alloys tested were

  1. Intermetallic alloy welding wires and method for fabricating the same

    DOEpatents

    Santella, Michael L. (Knoxville, TN); Sikka, Vinod K. (Oak Ridge, TN)

    1996-01-01

    Welding wires for welding together intermetallic alloys of nickel aluminides, nickel-iron aluminides, iron aluminides, or titanium aluminides, and preferably including additional alloying constituents are fabricated as two-component, clad structures in which one component contains the primary alloying constituent(s) except for aluminum and the other component contains the aluminum constituent. This two-component approach for fabricating the welding wire overcomes the difficulties associated with mechanically forming welding wires from intermetallic alloys which possess high strength and limited ductilities at elevated temperatures normally employed in conventional metal working processes. The composition of the clad welding wires is readily tailored so that the welding wire composition when melted will form an alloy defined by the weld deposit which substantially corresponds to the composition of the intermetallic alloy being joined.

  2. Intermetallic alloy welding wires and method for fabricating the same

    DOEpatents

    Santella, M.L.; Sikka, V.K.

    1996-06-11

    Welding wires for welding together intermetallic alloys of nickel aluminides, nickel-iron aluminides, iron aluminides, or titanium aluminides, and preferably including additional alloying constituents are fabricated as two-component, clad structures in which one component contains the primary alloying constituent(s) except for aluminum and the other component contains the aluminum constituent. This two-component approach for fabricating the welding wire overcomes the difficulties associated with mechanically forming welding wires from intermetallic alloys which possess high strength and limited ductilities at elevated temperatures normally employed in conventional metal working processes. The composition of the clad welding wires is readily tailored so that the welding wire composition when melted will form an alloy defined by the weld deposit which substantially corresponds to the composition of the intermetallic alloy being joined. 4 figs.

  3. Biological Role of Anions (Sulfate, Nitrate , Oxalate and Acetate) on the Antibacterial Properties of Cobalt (II) and Nickel(II) Complexes With Pyrazinedicarboxaimide Derived, Furanyl and Thienyl Compounds

    PubMed Central

    Praveen, M.

    1999-01-01

    A number of biologically active complexes of cobalt(II) and nickel(II) with pyrazinedicarboxaimido derived thienyl and furanyl compounds having the same metal ion but different anions such as sulphate, nitrate, oxalate and acetate have been synthesized and characterized on the basis of their physical, spectral and analytical data. In order to evaluate the role of anions on their antibacterial properties, these ligands and their synthesized metal complexes with various anions have been screened against bacterial species Escherichia coil,Pseudomonas aeruginosa and Staphylococcus aureus. The title studies have proved a definitive role of anions in increasing the antibacterial properties. PMID:18475887

  4. FIB-SEM investigation of trapped intermetallic particles in anodic oxide films

    E-print Network

    Dunin-Borkowski, Rafal E.

    of this investigation is to understand the structure of trapped intermetallics particles and localized compositionFIB-SEM investigation of trapped intermetallic particles in anodic oxide films on AA1050 aluminium/methodology/approach ­ The morphology and composition of Fe-containing intermetallic particles incorporated into the anodic oxide films

  5. Bulky N(,N)-(di)alkylethane-1,2-diamineplatinum(II) compounds as precursors for generating unsymmetrically substituted platinum(IV) complexes.

    PubMed

    Pichler, Verena; Göschl, Simone; Meier, Samuel M; Roller, Alexander; Jakupec, Michael A; Galanski, Markus; Keppler, Bernhard K

    2013-07-15

    Investigations of the influence of bulky groups in the equatorial ligand sphere of platinum(IV) compounds on the complexes' stability and reaction pattern were performed. Four dihydroxidoplatinum(IV) complexes were reacted with anhydrides, cinnamoyl chloride, and n-propyl isocyanate and yielded the symmetric dicarboxylated products or, if steric hindrance was observed, unsymmetrically substituted monocarboxylated analogues. With the aim of raising the steric demand, the following ligands were chosen: N-cyclohexylethane-1,2-diamine, N,N-dimethylethane-1,2-diamine, N,N-diethylethane-1,2-diamine, and N,N-diisopropylethane-1,2-diamine. All of the novel complexes were characterized by electrospray ionization mass spectrometry (ESI-MS), one- and two-dimensional NMR spectroscopy, elemental analysis, and reversed-phase HPLC; complexes B3, C3, C6, and D4 were also analyzed by X-ray diffraction. Additionally, the cytotoxicities of 10 compounds toward the cisplatin-sensitive cell line CH1 and the intrinsically cisplatin-resistant cell lines A549 and SW480 were investigated, and IC50 values down to the nanomolar range were found. To aid in the interpretation of structure-activity relationships, log k(w) values as a measure for the lipophilicity were determined for all of the new complexes, and the rates of reduction of C1, C3, and C4 relative to satraplatin were determined by means of NMR spectroscopy and ESI-MS. PMID:23790208

  6. Intermetallic crystal structures as foams. Beyond Frank-Kasper.

    PubMed

    Bonneau, Charlotte; O'Keeffe, Michael

    2015-02-01

    In many intermetallic structures, the atoms and bonds divide space into tilings by tetrahedra. The well-known Frank-Kasper phases are examples. The dual tilings divide space into a tiling by polyhedra that is topologically a foam. The number of faces of the dual polyhedron corresponds to the atom coordination number in the direct structure, and face sharing by adjacent polyhedra corresponds to bonds in the direct structure. A number of commonly occurring intermetallic crystal structures are shown as their duals. A major advantage of this alternative mode of depiction is that coordination of all of the atoms can be seen simultaneously. PMID:25247234

  7. Nickel-catalyzed asymmetric arylations of [alpha]-halocarbonyl compounds and studies of boratabenzene-containing transition metal complexes

    E-print Network

    Lundin, Pamela M. (Pamela Marie)

    2010-01-01

    Chapter 1 begins with a review of the current literature on cross-coupling methods to generate a-arylcarbonyl compounds, with a special emphasis on asymmetric arylations. The second section of chapter 1 describes the ...

  8. Molecular compounds based on DT-TTF and Au(cdc) 2 complex. Structural, magnetic and electrical properties

    Microsoft Academic Search

    Xavi Ribas; Marta Mas-Torrent; Concepció Rovira; Jaume Veciana; João C. Dias; Helena Alves; Elsa B. Lopes; Manuel Almeida; Klaus Wurst

    2003-01-01

    The synthesis and characterisation of two new radical ion salts based on the donor dithiophenetetrathiafulvalene (DT-TTF) and the anion Au(cdc)2? (cdc=cynanodithioimido carbonate) are described. These salts were characterised as the mixed valence compound (DT-TTF)2(Au(cdc)2) (1) and the completely ionic salt (DT-TTF)(Au(cdc)2) (2). The X-ray crystal structure of both compounds show that they are formed by chains of donor molecules separated

  9. Journal of ELECTRONIC MATERIALS, Vol. 33, No. 12, 2004 Special Issue Paper Intermetallic Phase Detection in Lead-Free Solders Using

    E-print Network

    Ekere, Ndy

    Detection in Lead-Free Solders Using Synchrotron X-Ray Diffraction GAVIN J. JACKSON,1 HUA LU,2,6 RAJ-ray diffraction (XRD) experiments to detect intermetallic compounds (IMCs) in lead-free solder bumps. The IMCs found in 95.5Sn3.8Ag0.7Cu solder bumps on Cu pads with electroplated-nickel immersion-gold (ENIG

  10. A flexible-protein molecular docking study of the binding of ruthenium complex compounds to PIM1, GSK-3?, and CDK2/Cyclin A protein kinases

    PubMed Central

    Liu, Yingting; Agrawal, Neeraj J.; Radhakrishnan, Ravi

    2012-01-01

    We employ ensemble docking simulations to characterize the interactions of two enantiomeric forms of a Ru-complex compound (1-R and 1-S) with three protein kinases, namely PIM1, GSK-3?, and CDK2/cyclin A. We show that our ensemble docking computational protocol adequately models the structural features of these interactions and discriminates between competing conformational clusters of ligand-bound protein structures. Using the determined X-ray crystal structure of PIM1 complexed to the compound 1-R as a control, we discuss the importance of including the protein flexibility inherent in the ensemble docking protocol, for the accuracy of the structure prediction of the bound state. A comparison of our ensemble docking results suggests that PIM1 and GSK-3? bind the two enantiomers in similar fashion, through two primary binding modes: conformation I, which is very similar to the conformation presented in the existing PIM1/compound 1-R crystal structure; conformation II, which represents a 180° flip about an axis through the NH group of the pyridocarbazole moiety, relative to conformation I. In contrast, the binding of the enantiomers to CDK2 is found to have a different structural profile including a suggested bound conformation, which lacks the conserved hydrogen bond between the kinase and the ligand (i.e., ATP, staurosporine, Ru-complex compound). The top scoring conformation of the inhibitor bound to CDK2 is not present among the top-scoring conformations of the inhibitor bound to either PIM1 or GSK-3? and vice-versa. Collectively, our results help provide atomic-level insights into inhibitor selectivity among the three kinases. PMID:22926267

  11. Crystal structures of three intermetallic phases in the Mo–Pt–Si system

    Microsoft Academic Search

    J.-M. Joubert; Ya. Tokaychuk; R. ?erný

    2010-01-01

    The crystal structures of three ternary Mo–Pt–Si intermetallic compounds have been determined ab initio from powder X-ray diffraction data. All three structures are representative of new structure types. Both the X (MoPt2Si3, Pmc21, oP12, a=3.48438(6), b=9.1511(2), c=5.48253(8)Å) and Y (MoPt3Si4, Pnma, oP32, a=5.51210(9), b=3.49474(7), c=24.3090(4)Å) phases derive from PtSi (FeAs type) structure while the Z phase (ideal composition Mo32Pt20Si16, refined

  12. Geometrically unprecedented 3-, 5- and 7-membered Hg(ii)-Cu(i) and Hg(ii)-Ag(i) thiolate clusters: precursors to intermetallics.

    PubMed

    Gupta, Geetika; Chaturvedi, Jyotsna; Bhattacharya, Subrato

    2015-05-01

    The syntheses of three polynuclear heterobimetallic complexes through the use of a homoleptic mercuric thiolate anion as a template for the assembly of coinage metal are presented. The complexes, [(PPh3)3Ag3(?-SPh)7Hg2] (), [Hg(?-SPh)4{Cu(PPh3)2}2] () and [(dppe)2Cu5(?-SPh)7Hg2(SPh)2] () were utilized as precursors for the fabrication of Hg-Ag and Hg-Cu intermetallics. PMID:25873179

  13. Rare earth transition metal magnesium compounds—An overview

    NASA Astrophysics Data System (ADS)

    Rodewald, Ute Ch.; Chevalier, Bernard; Pöttgen, Rainer

    2007-05-01

    Intermetallic rare earth-transition metal-magnesium compounds play an important role as precipitations in modern light weight alloys and as host materials for hydrogen storage applications. Recent results on the crystal chemistry, the chemical bonding peculiarities, physical properties, and hydrogenation behavior of these materials are reviewed.

  14. Determination of volatile organic compounds at the parts per trillion level in complex aqueous matrices using membrane introduction mass spectrometry

    SciTech Connect

    Bauer, S. (MIMS Technology Development Incorporated, West Lafayette, IN (United States)); Solyom, D. (Purdue Univ., West Lafayette, IN (United States))

    1994-12-15

    Recent advances in membrane introduction mass spectrometry (MIMS) have demonstrated the utility of MIMS in the trace level analysis of volatile organic compounds in water. The present study details the performance of an ion trap mass spectrometer fitted with a capillary membrane probe in the direct analysis of volatile organic compounds in water using flow injection techniques. Detection limits for 59 volatile organic compounds listed in EPA method 524.2 were determined to be in the mid to low parts per trillion (pptr) range using MIMS. Analyses of these compounds in untreated river water, sea water, and matrices containing strong acids and bases are demonstrated. The matrix studies show that there are no adverse effects on compound identification or detection limits resulting from matrix interferences in MIMS. Further experiments demonstrate the utility of MIMS as a direct analysis technique for on-line monitoring of trihalomethane formation in water treatment facilities. Detection limits of 100 pptr were obtained for the four trihalomethanes, with repetitive sample times averaging 6 min/sample. Quantitation of the total trihalomethane content was performed in one step, demonstrating further increases in analytical speed over traditional analysis methods. 26 refs., 9 figs., 2 tabs.

  15. Fabrication of NiAl intermetallic reactors for microtechnology-based energy chemical systems (MECS)

    SciTech Connect

    Alman, D.A.; Wilson, R.D.; Paul, B.K. (Oregon State Univ., Corvallis, OR)

    2001-01-01

    Microtechnology-based energy chemical systems (MECS) offer opportunities for portable power generation, on-site waste remediation, point-of-use chemical synthesis, and heat-transfer. The material requirements for this application include chemical inertness and the ability to be fabricated into structures that contain internal features of complex geometries and small (<250 micrometer) dimensions. It has been recognized that materials with limited formability, like ceramics and intermetallics, may be required for high temperature applications. In this paper, a method for forming an array of internal microchannels in a NiAl device is presented. Microchannels are precision machined (via laser ablation) into elemental Ni and Al foils. During bonding, these foils are converted into NiAl. Results show that this is a viable method for producing aluminide-based structure containing complex, internal features.

  16. Trace detection of organic compounds in complex sample matrixes by single photon ionization ion trap mass spectrometry: real-time detection of security-relevant compounds and online analysis of the coffee-roasting process.

    PubMed

    Schramm, Elisabeth; Kürten, Andreas; Hölzer, Jasper; Mitschke, Stefan; Mühlberger, Fabian; Sklorz, Martin; Wieser, Jochen; Ulrich, Andreas; Pütz, Michael; Schulte-Ladbeck, Rasmus; Schultze, Rainer; Curtius, Joachim; Borrmann, Stephan; Zimmermann, Ralf

    2009-06-01

    An in-house-built ion trap mass spectrometer combined with a soft ionization source has been set up and tested. As ionization source, an electron beam pumped vacuum UV (VUV) excimer lamp (EBEL) was used for single-photon ionization. It was shown that soft ionization allows the reduction of fragmentation of the target analytes and the suppression of most matrix components. Therefore, the combination of photon ionization with the tandem mass spectrometry (MS/MS) capability of an ion trap yields a powerful tool for molecular ion peak detection and identification of organic trace compounds in complex matrixes. This setup was successfully tested for two different applications. The first one is the detection of security-relevant substances like explosives, narcotics, and chemical warfare agents. One test substance from each of these groups was chosen and detected successfully with single photon ionization ion trap mass spectrometry (SPI-ITMS) MS/MS measurements. Additionally, first tests were performed, demonstrating that this method is not influenced by matrix compounds. The second field of application is the detection of process gases. Here, exhaust gas from coffee roasting was analyzed in real time, and some of its compounds were identified using MS/MS studies. PMID:19408912

  17. Wear of iron–aluminide intermetallic-based alloys and composites by hard particles

    SciTech Connect

    Alman, David E.; Hawk, Jeffrey A.; Tylczak, Jeffrey H.; Dogan, Cynthia P.; Wilson, Rick D.

    2001-10-01

    In this study, the resistance of alloys and composites based on the intermetallic compounds Fe3Al and FeAl to wear by hard particles was assessed and compared to the behavior of selected metals, alloys, other intermetallic compounds and ceramics. Pin abrasion tests were performed on these materials at room temperature. Among other things, it was found that as the Al atomic percent in binary Fe–Al increased, the alloys became more abrasion resistant. In summary, the ranking of the alloys in terms of abrasion resistance from the most resistant to the least resistant proceeds as follows: FeAl > Fe3Al > #1;-Fe alloy with 16 at.% Al > pure Fe > pure Al. These results are discussed in terms of the hardnesses of the respective alloys. The addition between 40 and 70 vol.% of a hard second phase (e.g. TiC or TiB2) decreased the wear rate of the Fe3Al and FeAl composites by an order of magnitude compared to the parent alloy. In addition, solid particle erosion tests were performed on an FeAl alloy, and FeAl + 80 vol.% TiC, FeAl + 80 vol.% WC, FeAl + 80 vol.% TiB2 cermets at 25, 180, 500 and 700?C, and the results were compared to erosion behavior of several conventional alloys and cemented carbides (WC–Co). The ranking of the erosion resistance of the FeAl alloys and composite materials was as follows: (most resistant) FeAl–WC > FeAl–TiB2 > FeAl–TiC > FeAl (least resistant). This behavior was related to both the cermet microstructure and material removal mechanisms.

  18. Optimisation of a multiphase intermetallic metal metal composite material

    E-print Network

    Cambridge, University of

    Optimisation of a multiphase intermetallic metal ± metal composite material J. D. Robson, N to as metal ± metal composites (MeMeCs). In these materials the strong but brittle b and b9 phases act. Duvauchelle, A. Lugan, J. Street, and H. K. D. H. Bhadeshia Metal ± metal composites (MeMeCs) manufactured

  19. Electronic structure of intermetallic B32 type Zintl phases

    Microsoft Academic Search

    Peter C. Schmidt

    The electronic properties of binary and ternary intermetallic Zintl phases crystallizing in the NaTl type of structure are investigated and reported. The crystal and defect structure, the electronic band structure and density of states, the bonding mechanisms and the charge transfer are discussed. Comparison is made between the electronic states in the B2 and the B32 types of structure. Furthermore,

  20. Bonding and Structure of Intermetallics: A New Bond Order Potential

    Microsoft Academic Search

    D. G. Pettifor; M. Aoki; J. N. Murrell; A. Cottrell; A. M. Stoneham

    1991-01-01

    Intermetallics such as the transition metal aluminides present theorists with a challenge since bonding is not well described by currently available pair or embedded atom potentials. We show that a new angularly dependent, many-body potential for the bond order has all the necessary ingredients for an adequate description. In particular, by linearizing the moment-recursion coefficient relations, a cluster expansion is

  1. From the Cover: Implications for complex cognition from the hafting of tools with compound adhesives in the Middle Stone Age, South Africa.

    PubMed

    Wadley, Lyn; Hodgskiss, Tamaryn; Grant, Michael

    2009-06-16

    Compound adhesives made from red ochre mixed with plant gum were used in the Middle Stone Age (MSA), South Africa. Replications reported here suggest that early artisans did not merely color their glues red; they deliberately effected physical transformations involving chemical changes from acidic to less acidic pH, dehydration of the adhesive near wood fires, and changes to mechanical workability and electrostatic forces. Some of the steps required for making compound adhesive seem impossible without multitasking and abstract thought. This ability suggests overlap between the cognitive abilities of modern people and people in the MSA. Our multidisciplinary analysis provides a new way to recognize complex cognition in the MSA without necessarily invoking the concept of symbolism. PMID:19433786

  2. Metal complexes of ONO donor Schiff base ligand as a new class of bioactive compounds; Synthesis, characterization and biological evolution

    NASA Astrophysics Data System (ADS)

    Kumar Naik, K. H.; Selvaraj, S.; Naik, Nagaraja

    2014-10-01

    Present work reviews that, the synthesis of (E)-N";-((7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)benzohydrazide [L] ligand and their metal complexes. The colored complexes were prepared of type [M2+L]X2, where M2+ = Mn, Co, Ni, Cu, Sr and Cd, L = (7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)benzohydrazide, X = Cl-. Ligand derived from the condensation of 8-formyl-7-hydroxy-4-methylcoumarin and benzohydrazide in the molar ratio 1:1 and in the molar ratio 1:2 for metal complexes have been prepared. The chelation of the ligand to metal ions occurs through the both oxygen groups, as well as the nitrogen atoms of the azomethine group of the ligand. Reactions of the Schiff base ligand with Manganese(II), Cobalt(II), Nickel(II), Copper(II), Strontium(II), and Cadmium(II) afforded the corresponding metal complexes. The structures of the obtained ligand and their respective metal complexes were elucidated by infra-red, elemental analysis, Double beam UV-visible spectra, conductometric measurements, magnetic susceptibility measurements and also thermochemical studies. The metal complex exhibits octahedral coordination geometrical arrangement. Schiff base ligand and their metal complexes were tested against antioxidants, antidiabetic and antimicrobial activities have been studied. The Schiff base metal complexes emerges effective ?-glucosidase inhibitory activity than free Schiff base ligand.

  3. Metal complexes of ONO donor Schiff base ligand as a new class of bioactive compounds: synthesis, characterization and biological evolution.

    PubMed

    Kumar Naik, K H; Selvaraj, S; Naik, Nagaraja

    2014-10-15

    Present work reviews that, the synthesis of (E)-N'-((7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)benzohydrazide [L] ligand and their metal complexes. The colored complexes were prepared of type [M(2+)L]X2, where M(2+)=Mn, Co, Ni, Cu, Sr and Cd, L=(7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)benzohydrazide, X=Cl(-). Ligand derived from the condensation of 8-formyl-7-hydroxy-4-methylcoumarin and benzohydrazide in the molar ratio 1:1 and in the molar ratio 1:2 for metal complexes have been prepared. The chelation of the ligand to metal ions occurs through the both oxygen groups, as well as the nitrogen atoms of the azomethine group of the ligand. Reactions of the Schiff base ligand with Manganese(II), Cobalt(II), Nickel(II), Copper(II), Strontium(II), and Cadmium(II) afforded the corresponding metal complexes. The structures of the obtained ligand and their respective metal complexes were elucidated by infra-red, elemental analysis, Double beam UV-visible spectra, conductometric measurements, magnetic susceptibility measurements and also thermochemical studies. The metal complex exhibits octahedral coordination geometrical arrangement. Schiff base ligand and their metal complexes were tested against antioxidants, antidiabetic and antimicrobial activities have been studied. The Schiff base metal complexes emerges effective ?-glucosidase inhibitory activity than free Schiff base ligand. PMID:24858195

  4. The effect of the amphoteric properties of amino acids in the zwitterionic form on the structure of iodine complex compounds in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Yuldasheva, Gulnara A.; Zhidomirov, Georgii M.; Leszczynski, Jerzy; Ilin, Aleksandr I.

    2013-02-01

    The donor-acceptor interactions in three model systems: water-glycine (a), water-glycine-KI3 (b), water-glycine-KI3-LiCl-ethanol (c) were investigated by UV-, IR-spectroscopy, and the quantum-chemical DFT-B3PW91/midi method. UV- and IR spectrum data for the considered systems agree well with the results of calculations of the spectral characteristics of glycine cluster that consists of six molecules, and models that simulate the influence of the zwitterionic form of glycine on the structure of complex iodine compounds in the systems (b-c). Localization of a negative and a positive charge at the ends of a zwitterion makes it possible for a cluster of glycine zwitterions to be formed in water. In such cluster glycine molecules are located under each other so that the protonated group is always under (or above) the carboxy group. Glycine fragments are bound by strong hydrogen bonds and also by hydrogen bonding interactions with water molecules. In the water-glycine-KI3-LiCl-ethanol system the cluster of glycine zwitterions splits the iodide ion into I- and I2 (I- reacts with the protonated amino group, and I2 with the carboxy group). This creates conditions for the formation of an iodine complex compound, in which molecular iodine reveals the acceptor properties towards glycine, and the donor properties towards the LiCl-ethanol complex.

  5. f-band narrowing in uranium intermetallics

    SciTech Connect

    Dunlap, B.D.; Litterst, F.J.; Malik, S.K.; Kierstead, H.A.; Crabtree, G.W.; Kwok, W.; Lam, D.J.; Mitchell, A.W.

    1987-01-01

    Although the discovery of heavy fermion behavior in uranium compounds has attracted a great deal of attention, relatively little work has been done which is sufficiently systematic to allow an assessment of the relationship of such behavior to more common phenomena, such as mixed valence, narrow-band effects, etc. In this paper we report bulk property measurements for a number of alloys which form a part of such a systematic study. The approach has been to take relatively simple and well-understood materials and alter their behavior by alloying to produce heavy fermion or Kondo behavior in a controlled way.

  6. A diffraction based study of the deformation mechanisms in anomalously ductile B2 intermetallics

    NASA Astrophysics Data System (ADS)

    Mulay, Rupalee Prashant

    For many decades, the brittle nature of most intermetallic compounds (e.g. NiAl) has been the limiting factor in their practical application. Many B2 (CsCl prototypical structure) intermetallics are known to exhibit slip on the <001>{110} slip mode, which provides only 3 independent slip systems and, hence, is unable to satisfy the von Mises (a.k.a. Taylor) criterion for polycrystalline ductility. As a result, inherent polycrystalline ductility is unexpected. Recent discovery of a number of ductile B2 intermetallics has raised questions about possible violation of the von Mises criterion by these alloys. These ductile intermetallic compounds are MR (metal (M) combined with a rare earth metal or group IV refractory metal (R)) alloys and are stoichiometric, ordered compounds. Single crystal slip trace analyses have only identified the presence of <100>{011} or <100>{010} slip systems. More than 100 other B2 MR compounds are known to exist and many of them have already been shown to be ductile (e.g., CuY, AgY, CuDy, CoZr, CoTi, etc.). Furthermore, these alloys exhibit a large Bauschinger effect. The present work uses several diffraction based techniques including electron back scattered diffraction (EBSD), X-ray diffraction (XRD) and in-situ neutron diffraction; in conjunction with scanning electron microscopy (SEM), transmission electron microscopy (TEM), mechanical testing, and crystal plasticity modeling, to elucidate the reason for ductility in select B2 alloys, explore the spread of this ductility over the B2 family, and understand the Bauschinger effect in these alloys. Several possible explanations (e.g., slip of <111> dislocations, strong texture, phase transformations and twinning) for the anomalous ductility were explored. An X-ray diffraction based analysis ruled out texture, phase purity and departure from order as explanations for the anomalous ductility in MR alloys. In-situ neutron diffraction and post deformation SEM, EBSD, and TEM were unable to detect any evidence for phase transformations in CoTi and CoZr. Also, post deformation characterization did not reveal any evidence of twinning. However, TEM based g·b analysis and EBSD based in-grain misorientation axis (IGMA) analysis showed that beyond a transition in the strain hardening behavior in CoTi, slip modes involving dislocations with <110> and <111> Burgers vectors are activated. The slip of such dislocations can reduce stress concentrations that could otherwise lead to premature fracture, thus providing a satisfying explanation for the anomalous ductility of CoTi and related compounds, like CoZr. Dislocation self-energy calculations accounting for elastic anisotropy suggest that the choice of slip direction in these alloys is mobility-, rather than source-, limited. The reach of this "ductilizing effect" over B2 alloys was explored by producing, characterizing, and testing a number of simple metal-rare earth metal compounds, namely MgY, MgNd and MgCe. MgR intermetallics with the B2 structure were found to be brittle and exhibit a cleavage type fracture indicating that the ductilizing effect is not as widespread as was initially thought. MgY and MgNd were found to primarily cleave along the {100} planes, while MgCe was found to cleave on the {111} planes. A large Bauschinger effect was observed in several of the anomalously ductile B2 compounds, such that the material actually begins to yield in the reverse direction on unloading. When only the primary slip mode <100>{011} is active in CoZr (prior to a transition in strain hardening), the buildup of intergranular stresses is large and is chiefly responsible for the observed Bauschinger effect. However, past the aforementioned transition in strain hardening, the effect of intergranular stresses diminishes. The results demonstrate that the activation of hard, secondary slip modes causes the internal strains to develop more uniformly among the grains, thus reducing the intergranular stresses which cause the Bauschinger effect. Crystal plas

  7. Alloying Effects on Creep and Oxidation Resistance of Austenitic Stainless Steel Alloys Employing Intermetallic Precipitates

    SciTech Connect

    Yamamoto, Yukinori [ORNL; Takeyama, Masao [Tokyo Institute of Technology; Lu, Zhao Ping [ORNL; Liu, Chain T [ORNL; Evans, Neal D [ORNL; Maziasz, Philip J [ORNL; Brady, Michael P [ORNL

    2008-01-01

    Microstructure evolution during creep testing at 750 C and 100 MPa of Fe-20Cr-30Ni-2Nb (at.%) alloys with and without 0.4 Si, 0.2 Zr or 5.0 Al additions has been studied, in order to explore the viability of Fe-rich austenitic stainless alloys strengthened by intermetallic phases. Fine Fe{sub 2}Nb Laves phase dispersions with the size of less than 1 {micro}m within the {gamma}-Fe matrix were obtained in the base and Si-modified alloys after aging at 800 C. The addition of Si helped to refine and stabilize the size of particles, resulting in finer and denser Fe{sub 2}Nb dispersion than that in the base alloy. The alloys with only solution heat-treatment exhibited superior creep resistance to the aged ones, which is due to dynamic precipitation of the Fe{sub 2}Nb Laves phase during creep testing with a size of 300-400 nm, resulting in more effective pinning of dislocations. The base alloy also showed the meta-stable {gamma}*-Ni{sub 3}Nb phase with a size of 50 nm during the transient state of the creep testing. The Zr-modified alloy achieved significant improvement of creep properties. This is hypothesized to be due to the stabilization of {delta}-Ni{sub 3}Nb phase relative to Fe{sub 2}Nb, resulting in the formation of multiple fine dispersions of stable intermetallic compounds of {delta} and Fe{sub 2}Nb within the {gamma}-Fe matrix. A small amount of a (Ni, Zr and Nb)-enriched unidentified phase was also observed. The addition of Al significantly improved the oxidation resistance because of the formation of protective alumina scales on the surface. The alloy also showed superior creep resistance to that of the base alloy due to the formation of a dense dispersion of spherical Ni{sub 3}Al, typically 30 nm in diameter. Collectively, these findings provide the alloy design basis for creep and oxidation-resistant austenitic stainless steel alloys via intermetallic precipitates.

  8. Theoretical energy release of thermites, intermetallics, and combustible metals

    SciTech Connect

    Fischer, S.H.; Grubelich, M.C.

    1998-06-01

    Thermite (metal oxide) mixtures, intermetallic reactants, and metal fuels have long been used in pyrotechnic applications. Advantages of these systems typically include high energy density, impact insensitivity, high combustion temperature, and a wide range of gas production. They generally exhibit high temperature stability, and possess insensitive ignition properties. In this paper, the authors review the applications, benefits, and characteristics of thermite mixtures, intermetallic reactants, and metal fuels. Calculated values for reactant density, heat of reaction (per unit mass and per unit volume), and reaction temperature (without and with consideration of phase changes and the variation of specific heat values) are tabulated. These data are ranked in several ways, according to density, heat of reaction, reaction temperature, and gas production.

  9. Sublattice effect on topological surface states in complex (SnTe )n>1(Bi2Te3)m=1 compounds

    NASA Astrophysics Data System (ADS)

    Eremeev, S. V.; Menshchikova, T. V.; Silkin, I. V.; Vergniory, M. G.; Echenique, P. M.; Chulkov, E. V.

    2015-06-01

    An exotic type of topological spin-helical surface state was found in layered van der Waals bonded (SnTe) n =2 ,3(Bi2Te3)m =1 compounds which comprise two covalently bonded band inverted sublattices, SnTe and Bi2Te3 , within a building block. This topological state demonstrates unusual dispersion within the band gap. The dispersion of the surface state has two linear sections of different slope with a shoulder feature between them. Such a dispersion of the topological surface state enables an effective switch of the velocity of topological carriers by means of applying an external electric field.

  10. Intermetallic alloy welding wires and method for fabricating the same

    Microsoft Academic Search

    Michael L. Santella; Vinod K. Sikka

    1996-01-01

    Welding wires for welding together intermetallic alloys of nickel aluminides, nickel-iron aluminides, iron aluminides, or titanium aluminides, and preferably including additional alloying constituents are fabricated as two-component, clad structures in which one component contains the primary alloying constituent(s) except for aluminum and the other component contains the aluminum constituent. This two-component approach for fabricating the welding wire overcomes the difficulties

  11. Electronic structure of cerium and light rare-earth intermetallics

    Microsoft Academic Search

    J. W. Allen; S. J. Oh; O. Gunnarsson; K. Schönhammer; M. B. Maple; M. S. Torikachvili; I. Lindau

    1986-01-01

    We give an overview of the use of the impurity Anderson Hamiltonian to describe the spectroscopic and low-energy thermodynamic properties of cerium intermetallics, with emphasis on interpreting 4f photoemission spectra. We show Ce valence-band resonant photoemission, Bremsstrahlung isochromat and 3d X-ray photoemission spectra for CeRu2, CeNi2, CeIr2 and CeAl, and give a complete theoretical analysis of the spectra. We summarize

  12. Crown compounds for anions. Spectroscopic and theoretical studies of complexation of borohydride anions with cyclic trimeric perfluoro- o-phenylenemercury

    Microsoft Academic Search

    L. N Saitkulova; E. V Bakhmutova; E. S Shubina; I. A Tikhonova; G. G Furin; V. I Bakhmutov; N. P Gambaryan; A. L Chistyakov; I. V Stankevich; V. B Shur; L. M Epstein

    1999-01-01

    It has been shown by IR and NMR spectroscopy that cyclic trimeric perfluoro-o-phenylenemercury (o-C6F4Hg)3 (1) is capable of binding borohydride anions in THF and 1,2-dichloroethane solutions to form complexes {[(o-C6F4Hg)3](BH4)2}2? (2) and {[(o-C6F4Hg)3]2(BH4)}? (3). According to the IR data, complex 2 contains both terminal and coordinated B–H bonds while all four B–H bonds of the BH4? ion are coordinated with

  13. Superplastic ceramics and intermetallics and their potential applications

    SciTech Connect

    Wadsworth, J.; Nieh, T.G.

    1994-11-01

    Recent advances in the basic understanding of superplasticity and superplastic forming of ceramics and intermetallics are reviewed. Fine-grained superplastic ceramics, including yttria-stabilized tetragonal zirconia polycrystal, Y- or MgO-doped Al{sub 2}O{sub 3} Hydroxyapatite, {beta}-spodumene glass ceramics, Al{sub 2}0{sub 3}-YTZP two-phase composites, SiC-Si{sub 3}N{sub 4} and Fe-Fe{sub 3}C composites, are discussed. Superplasticity in the nickel-base (e.g., Ni{sub 3}Al and Ni{sub 3}Si) and titanium-base intermetallics (TiAl and T1{sub 3}Al), is described. Deformation mechanisms as well as microstructural requirements and effects such as grain size, grain growth, and grain-boundary phases, on the superplastic deformation behavior am addressed. Factors that control the superplastic tensile elongation of ceramics are discussed. Superplastic forming, and particularly biaxial gas-pressure forming, of several ceramics and intermetallics are presented with comments on the likelihood of commercial application.

  14. Site preference, magnetism and lattice vibrations of intermetallics Lu2Fe17-xTx (T=Cr, Mn, Ru)

    NASA Astrophysics Data System (ADS)

    Li, Jin-Chun; Qian, Ping; Zhang, Zhen-Feng; Yuan, Xiao-Jian; Wang, Yi-Wen; Shen, Jiang; Chen, Nan-Xian

    2013-05-01

    We present an atomistic study on the phase stability, site preference and lattice constants of the rare earth intermetallics Lu2Fe17-xTx (T=Cr, Mn, Ru). The calculated preferential occupation site of ternary element T is found to be the 4f site. The order of site preference is given as 4f, 12k, 12j and 6g for Lu2Fe17-xTx. The calculated lattice parameters are corresponding to the experimental results. We have calculated the magnetic moments of Lu2Fe17-xTx compounds. Results show that the calculated total magnetic moment of Lu2Fe17 compound is M=37.34 ?B/f.u. In addition, the total and partial phonon densities of states are evaluated first for these complicated structures.

  15. First-principles investigations on vibrational, thermodynamic, mechanical properties and thermal conductivity of L12 Al3X (X = Sc, Er, Tm, Yb) intermetallics

    NASA Astrophysics Data System (ADS)

    Zhang, Xudong; Jiang, Wei

    2015-06-01

    The lattice dynamics, thermodynamic, mechanical properties and thermal conductivity of L12 Al3X (X = Sc, Er, Tm, Yb) intermetallics have been investigated from first-principles calculations by means of using the VASP code. Our results agree well with the previous experiments and calculations. The phonon dispersion curves and the density of phonon states have been calculated by means of using the PHONONPY code and compared with the experimental results. The four compounds stay dynamically stable in the L12 structure. We also calculated the thermodynamics properties and give the relationships between thermal parameters and temperature. The elastic constants of the considered compounds are satisfied with mechanical stability criteria. The related mechanical parameters predict that Al3Sc has higher hardness than the other three compounds, and four compounds all posses a brittle nature. The mechanical anisotropy is predicted by anisotropic constants AU and AZ. The results show that the four compounds are all elastically isotropic. We also calculated the thermal conductivity by means of the Clarke’s model and Cahill’s model and found that the thermal conductivity of the four intermetallics follows the order: Al3Sc > Al3Er > Al3Tm > Al3Yb.

  16. Synthesis and Characterization of Metal Complexes to be Employed in the Catalytic Depolymerization of Lignin Model Compounds

    SciTech Connect

    Chmely, S. C.; Kim, S.; Beckham, G. T.

    2012-01-01

    Lignin is an earth-abundant biopolymer that is grossly underutilized as a value stream in current biomass conversion technologies because there exist no economic and technically feasible routes for lignin depolymerization and upgrading to fuels and chemicals. The development of new mild and selective catalytic routes to depolymerize this recalcitrant biopolymer is required to more effectively utilize lignin. To that end, our group aims to synthesize and characterize a collection of organometallic catalysts to promote atom-economical catalytic lignin deconstruction. These catalysts have been screened against dimeric lignin model compounds in order to gain mechanistic insights into their modes of action. In addition, experimental efforts have been coupled with quantum mechanical calculations to elucidate solution behavior of the catalysts as well as the mechanisms of lignin depolymerization. Detailed synthetic procedures, as well as spectroscopic and crystallographic characterization and DFT calculations will be presented.

  17. Organometallic chemistry of bimetallic compounds

    SciTech Connect

    Casey, C.P.

    1991-07-01

    This report consists of six sections: heterobimetallic dihydrides, early-late transition metal heterobimetallic compounds, amphiphilic carbene complexes and hydroxycarbene complexes, diiron compounds with bridging hydrocarbon ligands, diphosphine chelates with natural bite angles near 120 degrees, and synthesis and reactions of M=M compounds. (WET)

  18. Local decomposition induced by dislocation motions inside tetragonal Al2Cu compound: slip system-dependent dynamics

    PubMed Central

    Chen, D.; Ma, X. L.

    2013-01-01

    Dislocations in a crystal are usually classified into several independent slip systems. Motion of a partial dislocation in monometallic crystals may remove or create stacking fault characterized with a partial of a lattice translation vector. However, it is recently known that motion of partial dislocations in complex structure, such as that inside an intermetallic Al2Cu compound, lead to a local composition deviation from its stoichiometric ratio and the resultant structure collapse. Here we report such a local decomposition behaviors are strongly dependent on slip system of dislocations. Under applied external stress, we have studied dislocation motion behaviors in the three independent slip systems of [001](110), [100]() and [110]() within tetragonal Al2Cu crystal by using molecular dynamics method. We found dislocation motions in all these slip systems result in local decomposition but their physical details differ significantly. PMID:24196169

  19. Solvent-assisted electrospray ionization for direct analysis of various compounds (complex) from low/nonpolar solvents and eluents.

    PubMed

    Zhang, Jun-Ting; Wang, Hao-Yang; Zhu, Wei; Cai, Ting-Ting; Guo, Yin-Long

    2014-09-16

    Electrospray ionization (ESI) is a powerful ionization technique with a wide range of applications. However, the analytes in low/nonpolar solvents cannot be analyzed directly in electrospray ionization-mass spectrometry (ESI-MS), because low/nonpolar solvents are incompatible with ESI, because of their low conductivity. To circumvent this problem, we introduce an electrospray-based ionization method termed solvent-assisted electrospray ionization (SAESI). With the help of electrospray solvents at the tip of the spray needle, compounds in "non-electrospray ionization-friendly" solvents can be ionized directly using solvent-assisted electrospray ionization-mass spectrometry (SAESI-MS). The key features that the assistant solvent can be chosen flexibly and makes little interference to samples lead to better ionization performance in detection of organic reaction intermediates and real-time analysis of polymers and chiral drugs separated by gel permeation chromatography (GPC) and normal phase liquid chromatography (NPLC). Furthermore, it can achieve online hydrogen/deuterium (H/D) exchange reaction and even mitigate the signal suppression caused by strong acid modifiers in liquid chromatography. In addition, all parts of this device are commercially available and it only requires two parameters to be optimized, which makes SAESI easy to handle. PMID:25136838

  20. Compound RYR1 heterozygosity resulting in a complex phenotype of malignant hyperthermia susceptibility and a core myopathy.

    PubMed

    Kraeva, N; Heytens, L; Jungbluth, H; Treves, S; Voermans, N; Kamsteeg, E; Ceuterick-de Groote, C; Baets, J; Riazi, S

    2015-07-01

    Malignant hyperthermia (MH) is a potentially fatal pharmacogenetic myopathy triggered by exposure to volatile anesthetics and/or depolarizing muscle relaxants. Susceptibility to MH is primarily associated with dominant mutations in the ryanodine receptor type 1 gene (RYR1). Recent genetic studies have shown that RYR1 variants are the most common cause of dominant and recessive congenital myopathies - central core and multi-minicore disease, congenital fiber type disproportion, and centronuclear myopathy. However, the MH status of many patients, especially with recessive RYR1-related myopathies, remains uncertain. We report the occurrence of a triplet of RYR1 variants, c.4711A>G (p.Ile1571Val), c.10097G>A (p.Arg3366His), c.11798A>G (p.Tyr3933Cys), found in cis in four unrelated families, one from Belgium, one from The Netherlands and two from Canada. Phenotype-genotype correlation analysis indicates that the presence of the triplet allele alone confers susceptibility to MH, and that the presence of this allele in a compound heterozygous state with the MH-associated RYR1 variant c.14545G>A (p.Val4849Ile) results in the MH susceptibility phenotype and a congenital myopathy with cores and rods. Our study underlines the notion that assigning pathogenicity to individual RYR1 variants or combination of variants, and counseling in RYR1-related myopathies may require integration of clinical, histopathological, in vitro contracture testing, MRI and genetic findings. PMID:25958340

  1. Vertebrate pheromones and other semiochemicals: the potential for accommodating complexity in signalling by volatile compounds for vertebrate management.

    PubMed

    Pickett, John A; Barasa, Stephen; Birkett, Michael A

    2014-08-01

    The interaction between volatile and non-volatile, e.g. proteinaceous, components of pheromone and other semiochemical-based signalling systems presents a daunting set of problems for exploitation in the management of vertebrates, good or bad. Aggravating this is the complexity of the mixtures involved with pheromones, not only by definition associated with each species, but also with individual members of that species and their positions within their immediate communities. Nonetheless, already in some contexts, particularly where signals are perceived at other trophic levels from those of the vertebrates, e.g. by arthropods, reductionist approaches can be applied whereby the integrity of complex volatile mixtures is maintained, but perturbed by augmentation with individual components. In the present article, this is illustrated for cattle husbandry, fish farming and human health. So far, crude formulations have been used to imitate volatile semiochemical interactions with non-volatile components, but new approaches must be developed to accommodate more sophisticated interactions and not least the activities of the non-volatile, particularly proteinaceous components, currently being deduced. PMID:25109967

  2. Simple and Excellent Selective Chemiluminescence-Based CS2 On-Line Detection System for Rapid Analysis of Sulfur-Containing Compounds in Complex Samples.

    PubMed

    Zhang, Runkun; Li, Gongke; Hu, Yufei

    2015-06-01

    To study the interesting chemical reaction phenomenon can greatly contribute to the development of an innovative analytical method. In this paper, a simple CL reaction cell was constructed to study the chemiluminescence (CL) emission from the thermal oxidation of carbon disulfide (CS2). We found that the CL detection of CS2 exhibits unique characteristics of excellent selectivity and rapid response capacity. Experimental investigations together with theoretical calculation were performed to study the mechanism behind the CL reaction. The results revealed that the main luminous intermediates generated during the thermal degradation of CS2 are SO2* and CO2*. Significantly, this CL emission phenomenon has a wide application due to many sulfur-containing compounds that can convert to CS2 under special conditions. On the basis of this scheme, a CS2-generating and detection system was developed for rapid measurement of CS2 or other compounds that can convert to CS2. The usefulness of the system was demonstrated by measuring dithiocarbamate (DTC) pesticides (selected mancozeb as a representative analyte) based on the evolution of CS2 in spiked agricultural products. Results showed that the system allows online and large volume detection of CS2 under nonequilibrium condition, which greatly reduces the analytical time. The concentrations of mancozeb in the spiked samples were well-quantified with satisfied recoveries of 76.9-97.3%. The system not only addresses the urgent need for rapid in-field screening of DTC residues in foodstuffs but also opens a new opportunity for the fast, convenient, and cost-effective detection of CS2 and some other sulfur-containing compounds in complex samples. PMID:25913203

  3. Competing Anisotropies in the Ferromagnetic Kondo-Lattice Compound YbNiSn: Observation of a Complex Magnetic Ground State under High Pressure

    SciTech Connect

    Drescher, K.; Abd-Elmeguid, M.M.; Micklitz, H.; Sanchez, J.P. [II. Physikalisches Institut, Universitat zu Koln, Zulpicher Strasse 77, 50937 Koln (Germany)] [II. Physikalisches Institut, Universitat zu Koln, Zulpicher Strasse 77, 50937 Koln (Germany); [Departement de Recherche Fondamentale sur la Matiere Condensee, CEA/Grenoble, 17 Rue des Martyrs, 38054 Grenoble Cedex 9 (France)

    1996-10-01

    The {sup 170}Yb high pressure M{umlt o}ssbauer-effect technique has been used to investigate on a microscopic level the ground state properties of the ferromagnetic (FM) Kondo-lattice compound YbNiSu. Unlike general expectations, we find for 0{le}{ital p}{le}3GPa a stable moment behavior while {ital T}{sub {ital C}} is enhanced to its maximum value. For {ital p}{approx_gt}3GPa we observe a gradual change of the FM state to a complex magnetic ground state. This is suggested to be due to a volume dependent competition between the anisotropy of the magnetic exchange interaction and the crystal electric field anisotropy. {copyright} {ital 1996 The American Physical Society.}

  4. Amino Acid Synthesis from CO-N2 and CO-N2-H2 Gas Mixtures Via Complex Organic Compounds

    NASA Astrophysics Data System (ADS)

    Miyakawa, S.; Kobayashi, K.; Sawaoka, A. B.

    1999-01-01

    Reaction among hydrogen cyanide (HCN), formaldehyde (H2CO) and ammonia (NH3) are generally considered an important reaction in amino acid synthesis by electric discharge. Precursors of glycine and aspartic acid were, however, synthesized by adding water to metastable complex compounds produced by quenching a CO-N2 high-temperature plasma. In order to investigate effects of water remaining in an experimental vacuum chamber, optical emission spectroscopic and mass spectrometric measurements were conducted with CO-N2 and CO-N2-H2 gas mixtures. Although residual hydrogen atoms were detected in the CO-N2 experiment, the amount of them was much less than that in the CO-N2-H2 experiment

  5. Mixed 3d/4f polynuclear complexes with 2,2?-oxydiacetate as bridging ligand: Synthesis, structure and chemical speciation of La M compounds (M = bivalent cation)

    NASA Astrophysics Data System (ADS)

    Domínguez, Sixto; Torres, Julia; Peluffo, Florencia; Mederos, Alfredo; González-Platas, Javier; Castiglioni, Jorge; Kremer, Carlos

    2007-03-01

    Heterometallic compounds containing La(III), bivalent cations M (M = Co, Ni, Ca), and 2,2?-oxydiacetate (oda) as connecting ligand have been prepared and characterized. The complexes can be formulated as [La2M3(oda)6(H2O)6] · 12H2O. The structure of [La2Co3(oda)6(H2O)6] shows the presence of the La(III) coordinated by six carboxy and three ether oxygen atoms, and the Co(II) cation bonded to four carboxy oxygens and two molecules of water. An open 3D framework is observed, containing large hexagonal channels. The chemical systems were also investigated in solution (25.0 °C, I = 0.5 M Me4NCl) by potentiometry. The same kind of polynuclear species have been found in aqueous solution.

  6. The Electronic, Elastic, and Structural Properties of Ti-Pd Intermetallics and Associated Hydrides from First-Principles Calculations

    SciTech Connect

    Chen, Xingqiu [ORNL; Fu, Chong Long [ORNL; Morris, James R [ORNL

    2010-01-01

    Using an ab initio density functional approach, we report on the ground-state phase stabilities, enthalpies of formation, electronic, and elastic properties of the Ti-Pd alloy system. The calculated enthalpies of formation are in excellent agreement with available calorimetric data. We found a linear dependence between the calculated enthalpies of formation of several intermetallic structures and the Pd-concentration, indicating that each of these compounds has a very limited composition range. The elastic constants for many of these Ti-Pd intermetallics were calculated and analyzed. The B2 TiPd phase is found to be mechanically unstable with respect to the transformation into the monoclinic B19 structure. A series of hydrides, Ti2PdHx (x=1, 1.5, 2, 3, 4), have been investigated in terms of electronic structure, enthalpies of hydrogen absorption, and site preference of H atoms. Our results illustrate the physical mechanism for hydrogen absorption in term of the charge transfer, and explain why TiPd2 does not form a stable hydride.

  7. Development of intermetallic coatings for fusion power applications

    SciTech Connect

    Park, J.H.; Domenico, T.; Dragel, G.; Clark, R.

    1994-03-01

    In the design of liquid-metal cooling systems, corrosion resistance of structural materials and magnetohydrodynamic (MHD) force and its subsequent influence on thermal hydraulics and corrosion are major concerns. The objective of this study is to develop stable corrosion-resistant electrical insulator coatings at the liquid-metal/structural-material interface, with emphasis on electrically insulating coatings that prevent adverse MHD-generated currents from passing through the structural walls. Vanadium and V-base alloys are potential materials for structural applications in a fusion reactor. Insulator coatings inside the tubing are required when the system is cooled by liquid metals. Various intermetallic films were produced on V, V-t, and V-20 Ti, V-5Cr-t and V-15Cr-t, and Ti, and Types 304 and 316 stainless steel. The intermetallic layers were developed by exposure of the materials to liquid lithium of 3--5 at.% and containing dissolved metallic solutes at temperatures of 416--880{degrees}C. Subsequently, electrical insulator coatings were produced by reaction of the reactive layers with dissolved nitrogen in liquid lithium or by air oxidation under controlled conditions at 600--1000{degrees}C. These reactions converted the intermetallic layers to electrically insulating oxide/nitride or oxy-nitride layers. This coating method could be applied to a commercial product. The liquid metal can be used over and over because only the solutes are consumed within the liquid metal. The technique can be applied to various shapes because the coating is formed by liquid-phase reaction. This paper will discuss initial results on the nature of the coatings and their in-situ electrical resistivity characteristics in liquid lithium at high temperatures.

  8. Conversion of the under bump metallurgy into intermetallics: the impact on flip chip reliability

    Microsoft Academic Search

    Frank Stepniak

    2001-01-01

    In high temperature applications, the conversion of the under bump metallurgy (UBM) into UBM-Sn intermetallics can ultimately limit the reliability of flip chip components. Here, an intermetallic growth model characterizing the rate of electrical failure to the rate of UBM consumption is developed which derives a relationship between field reliability and accelerated temperature tests. For a flip chip structure employing

  9. EVOLUTION OF OXIDE SCALES ON FeAl GRADE 3 INTERMETALLIC F. Pedraza1

    E-print Network

    Boyer, Edmond

    on either the binary FeAl or its yttrium oxide dispersion strengthened (ODS) counterpart have indicatedEVOLUTION OF OXIDE SCALES ON FeAl GRADE 3 INTERMETALLIC ALLOY F. Pedraza1 , J.L. Grosseau-Poussard2@univ-lr.fr Abstract The ODS FeAl Grade 3 intermetallic alloy have been shown to develop a structured oxide scale upon

  10. An investigation of the cyclic fatigue and fracture behavior of a niobium aluminide intermetallic

    Microsoft Academic Search

    D. G. Konitzer

    1997-01-01

    This paper presents the results of a study designed to improve our understanding of the cyclic fatigue and fracture characteristics of a niobium aluminide intermetallic. Specimens of the intermetallic were deformed to failure in uniaxial tension, fully-reversed total strain amplitude control and cyclic stress amplitude control. The alloy exhibited limited plasticity and life under strain amplitude-controlled fatigue. Cyclic stress controlled

  11. Exo-Melt{trademark} process for intermetallic powders

    SciTech Connect

    Sikka, V.K. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.; Deevi, S.C. [Philip Morris U.S.A., Richmond, VA (United States). Research Center

    1996-06-01

    The methods of powder production for intermetallics are reviewed. An innovative method known as Exo-Melt{trademark} is described for producing molten aluminides for gas- and water-atomization processes that require a molten metal stream. The Exo-Melt{trademark} process is based on the effective utilization of the heats of formation of aluminides from their constituent elements. The Exo-Melt{trademark} process principles are discussed along with a description of a furnace-loading sequence that uses the principles for practical applications. The benefits of the Exo-Melt{trademark} process are compared with the problems associated with the conventional melting process.

  12. Microplasticity and fatigue in a damage tolerant niobium aluminide intermetallic

    SciTech Connect

    Soboyejo, W.O.; DiPasquale, J. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering; Srivatsan, T.S. [Univ. of Akron, OH (United States). Dept. of Mechanical Engineering; Konitzer, D. [General Electric Aircraft Engines, Cincinnati, OH (United States)

    1997-12-31

    In this paper, the micromechanisms of microplasticity and fatigue are elucidated for a damage tolerant niobium aluminide intermetallic deformed to failure under both monotonic and cyclic loading. Localized microplasticity is shown to occur by the formation of slip bands at stresses as low as 9% of the bulk yield stress. Formation and presence of slip bands is also observed upon application of the first cycle of fatigue load. The deformation and cracking phenomena are discussed in light of classical fatigue crack initiation and propagation models. The implications of microplasticity are elucidated for both fatigue crack initiation and crack growth.

  13. Superconducting compounds and alloys research

    NASA Technical Reports Server (NTRS)

    Otto, G.

    1975-01-01

    Resistivity measurements as a function of temperature were performed on alloys of the binary material system In sub(1-x) Bi sub x for x varying between 0 and 1. It was found that for all single-phase alloys (the pure elements, alpha-In, and the three intermetallic compounds) at temperatures sufficiently above the Debye-temperature, the resistivity p can be expressed as p = a sub o T(n), where a sub o and n are composition-dependent constants. The same exponential relationship can also be applied for the sub-system In-In2Bi, when the two phases are in compositional equilibrium. Superconductivity measurements on single and two-phase alloys can be explained with respect to the phase diagram. There occur three superconducting phases (alpha-In, In2Bi, and In5Bi3) with different transition temperatures in the alloying system. The magnitude of the transition temperatures for the various intermetallic phases of In-Bi is such that the disappearance or occurrence of a phase in two component alloys can be demonstrated easily by means of superconductivity measurements.

  14. Complexes of dual-function hemoglobin/dehaloperoxidase with substrate 2,4,6-trichlorophenol are inhibitory and indicate binding of halophenol to compound I.

    PubMed

    Wang, Chunxue; Lovelace, Leslie L; Sun, Shengfang; Dawson, John H; Lebioda, Lukasz

    2013-09-10

    The hemoglobin of sea worm Amphitrite ornata, which for historical reasons is abbreviated as DHP for dehaloperoxidase, has two physiological functions: it binds dioxygen in the ferrous state and dehalogenates halophenols, such as 2,4,6-trichlorophenol (TCP), using hydrogen peroxide as the oxidant in the ferric state. The crystal structures of three DHP variants (Y34N, Y34N/S91G, and L100F) with TCP bound show two mutually exclusive modes of substrate binding. One of them, the internal site, is deep inside the distal pocket with the phenolic OH moiety forming a hydrogen bond to the water molecule coordinated to the heme Fe. In this complex, the distal histidine is predominantly located in the closed position and also forms a hydrogen bond to the phenolic hydroxide. The second mode of TCP binding is external, at the heme edge, with the halophenol molecule forming a lid covering the entrance to the distal cavity. The distal histidine is in the open position and forms a hydrogen bond to the OH group of TCP, which also hydrogen bonds to the hydroxyl of Tyr38. The distance between the Cl4 atom of TCP and the heme Fe is 3.9 Å (nonbonding). In both complexes, TCP molecules prevent the approach of hydrogen peroxide to the heme, indicating that the complexes are inhibitory and implying that the substrates must bind in an ordered fashion: hydrogen peroxide first and TCP second. Kinetic studies confirmed the inhibition of DHP by high concentrations of TCP. The external binding mode may resemble the interaction of TCP with Compound I, the catalytic intermediate to which halophenols bind. The measured values of the apparent Km for TCP were in the range of 0.3-0.8 mM, much lower than the concentrations required to observe TCP binding in crystals. This indicates that during catalysis TCP binds to Compound I. Mutant F21W, which likely has the internal TCP binding site blocked, has ~7% of the activity of wild-type DHP. PMID:23952341

  15. Theoretical Energy Release of Thermites, Intermetallics, and Combustible Metals

    SciTech Connect

    Fischer, S.H.; Grubelich, M.C.

    1999-05-14

    Thermite mixtures, intermetallic reactants, and metal fuels have long been used in pyrotechnic applications. Advantages of these systems typically include high energy density, high combustion temperature, and a wide range of gas production. They generally exhibit high temperature stability and possess insensitive ignition properties. For the specific applications of humanitarian demining and disposal of unexploded ordnance, these pyrotechnic formulations offer additional benefits. The combination of high thermal input with low brisance can be used to neutralize the energetic materials in mines and other ordnance without the "explosive" high-blast-pressure events that can cause extensive collateral damage to personnel, facilities, and the environment. In this paper, we review the applications, benefits, and characteristics of thermite mixtures, intermetallic reactants, and metal fuels. Calculated values for reactant density, heat of reaction (per unit mass and per unit volume), and reaction temperature (without and with consideration of phase changes and the variation of specific heat values) are tabulated. These data are ranked in several ways, according to density, heat of reaction, reaction temperature, and gas production.

  16. SURFACE MODIFICATION OF ZIRCALOY-4 SUBSTRATES WITH NICKEL ZIRCONIUM INTERMETALLICS

    SciTech Connect

    Luscher, Walter G.; Gilbert, Edgar R.; Pitman, Stan G.; Love, Edward F.

    2013-02-01

    Surfaces of Zircaloy-4 (Zr-4) substrates were modified with nickel-zirconium (NiZr) intermetallics to tailor oxidation performance for specialized applications. Surface modification was achieved by electroplating Zr-4 substrates with nickel (Ni) and then performing thermal treatments to fully react the Ni plating with the substrates, which resulted in a coating of NiZr intermetallics on the substrate surfaces. Both plating thickness and thermal treatment were evaluated to determine the effects of these fabrication parameters on oxidation performance and to identify an optimal surface modification process. Isothermal oxidation tests were performed on surface-modified materials at 290°, 330°, and 370°C under a constant partial pressure of oxidant (i.e., 1 kPa D2O in dry Ar at 101 kPa) for 64 days. Test results revealed an enhanced, transient oxidation rate that decreased asymptotically toward the rate of the Zr-4 substrate. Oxidation kinetics were analyzed from isothermal weight gain data, which were correlated with microstructure, hydrogen pickup, strength, and hardness.

  17. New promising bulk thermoelectrics: intermetallics, pnictides and chalcogenides

    NASA Astrophysics Data System (ADS)

    Gonçalves, Antonio P.; Godart, Claude

    2014-02-01

    The need of alternative "green" energy sources has recently renewed the interest in thermoelectric (TE) materials, which can directly convert heat to electricity or, conversely, electric current to cooling. The thermoelectric performance of a material can be estimated by the so-called figure of merit, zT = ? ? 2 T/ ? ( ? the Seebeck coefficient, ? ? 2 the power factor, ? and ? the electrical and thermal conductivity, respectively), that depends only on the material. In the middle 1990s the "phonon glass and electron crystal" concept was developed, which, together with a better understanding of the parameters that affect zT and the use of new synthesis methods and characterization techniques, has led to the discovery of improved bulk thermoelectric materials that start being implemented in applications. During last decades, special focus has been made on skutterudites, clathrates, half-Heusler alloys, Si1- x Ge x-, Bi2Te3- and PbTe-based materials. However, many other materials, in particular based on intermetallics, pnictides, chalcogenides, oxides, etc. are now emerging as potential advanced bulk thermoelectrics. Herein we discuss the current understanding in this field, with special emphasis on the strategies to reduce the lattice part of the thermal conductivity and maximize the power factor, and review those new potential thermoelectric bulk materials, in particular based on intermetallics, pnictides and chalcogenides. A final chapter, discussing different shaping techniques leading to bulk materials (eventually from nanostructured TE materials), is also included.

  18. Designing materials for plasmonic systems: the alkali-noble intermetallics.

    PubMed

    Blaber, M G; Arnold, M D; Ford, M J

    2010-03-10

    We use electronic structure calculations based upon density functional theory to search for ideal plasmonic materials among the alkali-noble intermetallics. Importantly, we use density functional perturbation theory to calculate the electron-phonon interaction and from there use a first order solution to the Boltzmann equation to estimate the phenomenological damping frequency in the Drude dielectric function. We discuss the necessary electronic features of a plasmonic material and investigate the optical properties of the alkali-noble intermetallics in terms of some generic plasmonic system quality factors. We conclude that at low negative permittivities, KAu, with a damping frequency of 0.0224 eV and a high optical gap to bare plasma frequency ratio, outperforms gold and to some extent silver as a plasmonic material. Unfortunately, a low plasma frequency (1.54 eV) reduces its utility in modern plasmonics applications. We also discuss, briefly, the effect of local fields on the optical properties of these materials. PMID:21389416

  19. Valence, coordination number, and PAV cells in metallic rare earth compounds F. L. Carter

    E-print Network

    Paris-Sud XI, Université de

    Valence, coordination number, and PAV cells in metallic rare earth compounds F. L. Carter Naval, generalized coordination numbers, and Pauling's metallic valences are given for 24 intermetallic rare earth self-consistently it was necessary to increase the rare earth metal (/-character and hence decrease

  20. Rare earth–transition metal–magnesium compounds—An overview

    Microsoft Academic Search

    Ute Ch. Rodewald; Bernard Chevalier; Rainer Poettgen

    2007-01-01

    Intermetallic rare earth–transition metal–magnesium compounds play an important role as precipitations in modern light weight alloys and as host materials for hydrogen storage applications. Recent results on the crystal chemistry, the chemical bonding peculiarities, physical properties, and hydrogenation behavior of these materials are reviewed.

  1. Ab Initio Study of Binary and Ternary Nb3(X,Y) A15 Intermetallic Phases (X,Y = Al, Ge, Si, Sn)

    NASA Astrophysics Data System (ADS)

    Papadimitriou, Ioannis; Utton, Claire; Scott, Andrew; Tsakiropoulos, Panos

    2015-02-01

    Elastic and thermodynamic properties of binary and ternary A15 phases containing Al, Ge, Si, and Sn were studied using the first-principles pseudopotential plane-wave method based on density functional theory. The temperature dependence of the enthalpy of formation for the A15 intermetallics is reported using the quasiharmonic approximation. Elastic properties of the studied compounds were calculated at T = 0 K and were in agreement with the measured values reported in the literature. The elastic properties and thermodynamic data for the metastable A15-Nb3Si are reported for the first time. The Nb3Si has the highest bulk, shear, and Young's modulus values and is predicted to be less ductile than the other three binary A15 intermetallics. The calculations suggest (i) that Al and Sn have a positive effect on the ductility of the A15 compounds of this study, (ii) that Ge as a ternary addition has a ductilizing effect only in the A15-Nb3Si, and (iii) that Si as a ternary addition has a negative effect on the ductility of all the A15 compounds of the present study. The linear thermal expansion coefficients of the Nb, Al, the A15 Nb3Al, Nb3Ge, Nb3Sn, and Nb3Si (A15) phases are reported. The Sn and Al additions in the Nb3Si stabilize the A15 structure, while the Ge addition has the opposite effect, stabilizing the tP32 Nb3Si.

  2. Structures of intermetallic phases formed during immersion of H13 tool steel in an Al–11Si–3Cu die casting alloy melt

    Microsoft Academic Search

    Z. W. Chen; D. T. Fraser; M. Z. Jahedi

    1999-01-01

    The structures of intermetallic alloy layers formed during immersion of H13 tool steel into an aluminium die casting alloy melt have been studied by X-ray diffraction. Energy dispersive spectroscopy (EDS) analysis on the intermetallic phases was also conducted. A thick composite layer away from the H13 steel substrate consisted of irregular intermetallics and solidified cast alloy. A thin intermetallic layer

  3. Innovative processing to produce advanced intermetallic materials. Phase 1 final report

    SciTech Connect

    Loutfy, R.O.

    1989-09-01

    The program demonstrates the technical feasibility of synthesizing submicron titanium aluminide in a thermal rf plasma. Micron and submicron spherical titanium aluminide particles are produced in argon, hydrogen, and argon/hydrogen plasmas from the reaction of TiCl4(g), and Al(g). The ratio of Ti and Al is varied to produce the compounds Ti3Al, TiAl, and TiAl3. Microalloying with boron and macroalloying with niobium is demonstrated. Ti3Al whiskers can be produced, as well as other intermetallics of niobium aluminide, nickel aluminide, and molybdenum disilicide in the plasma synthesis process. Since submicron particles are produced, they have a high surface area and are sensitive to oxidation if not treated with a fugitive protective coating or utilized in a nonoxidizing atmosphere. Ti3Al particles are consolidated and utilized as a matrix for TiC and AlN composites. The submicron AlTi3 has significantly higher strength at room temperature than reported for commercial Ti3Al-11Nb alloy and useable strength is maintained up to 1000 C. The elongation is about the same as for commercial material because of possible oxide contamination in powder handling. However, dimpling and nacking is evident in the fracture surface, which suggests true room temperature ductility. Titanium aluminides have the potential to replace superalloys and become the dominant material for aerospace engines, air frames and skins for hypersonic vehicles.

  4. Incorporation of Interfacial Intermetallic Morphology in Fracture Mechanism Map for Sn-Ag-Cu Solder Joints

    NASA Astrophysics Data System (ADS)

    Huang, Z.; Kumar, P.; Dutta, I.; Sidhu, R.; Renavikar, M.; Mahajan, R.

    2014-01-01

    A fracture mechanism map (FMM) is a powerful tool which correlates the fracture behavior of a material to its microstructural characteristics in an explicit and convenient way. In the FMM for solder joints, an effective thickness of the interfacial intermetallic compound (IMC) layer ( t eff) and the solder yield strength ( ? ys,eff) are used as abscissa and ordinate axes, respectively, as these two predominantly affect the fracture behavior of solder joints. Earlier, a definition of t eff, based on the uniform thickness of IMC ( t u) and the average height of the IMC scallops ( t s), was proposed and shown to aptly explain the fracture behavior of solder joints on Cu. This paper presents a more general definition of t eff that is more widely applicable to a range of metallizations, including Cu and electroless nickel immersion gold (ENIG). Using this new definition of t eff, mode I FMM for SAC387/Cu joints has been updated and its validity was confirmed. A preliminary FMM for SAC387/Cu joints with ENIG metallization is also presented.

  5. Characterization of ceramics and intermetallics fabricated by self-propagating high-temperature synthesis

    SciTech Connect

    Hurst, J.B.

    1989-05-01

    Three efforts aimed at investigating the process of self-propagating high temperature synthesis (SHS) for the fabrication of structural ceramics and intermetallics are summarized. Of special interest was the influence of processing variables such as exothermic dopants, gravity, and green state morphology in materials produced by SHS. In the first effort directed toward the fabrication of SiC, exothermic dopants of yttrium and zirconium were added to SiO2 or SiO2 + NiO plus carbon powder mix and processed by SHS. This approach was unsuccessful since it did not produce the desired product of crystalline SiC. In the second effort, the influence of gravity was investigated by examining Ni-Al microstructures which were produced by SHS combustion waves traveling with and opposite the gravity direction. Although final composition and total porosities of the combusted Ni-Al compounds were found to be gravity independent, larger pores were created in those specimens which were combusted opposite to the gravity force direction. Finally, it was found that green microstructure has a significant effect on the appearance of the combusted piece. Severe pressing laminations were observed to arrest the combustion front for TiC samples.

  6. Characterization of ceramics and intermetallics fabricated by self-propagating high-temperature synthesis

    NASA Technical Reports Server (NTRS)

    Hurst, Janet B.

    1989-01-01

    Three efforts aimed at investigating the process of self-propagating high temperature synthesis (SHS) for the fabrication of structural ceramics and intermetallics are summarized. Of special interest was the influence of processing variables such as exothermic dopants, gravity, and green state morphology in materials produced by SHS. In the first effort directed toward the fabrication of SiC, exothermic dopants of yttrium and zirconium were added to SiO2 or SiO2 + NiO plus carbon powder mix and processed by SHS. This approach was unsuccessful since it did not produce the desired product of crystalline SiC. In the second effort, the influence of gravity was investigated by examining Ni-Al microstructures which were produced by SHS combustion waves traveling with and opposite the gravity direction. Although final composition and total porosities of the combusted Ni-Al compounds were found to be gravity independent, larger pores were created in those specimens which were combusted opposite to the gravity force direction. Finally, it was found that green microstructure has a significant effect on the appearance of the combusted piece. Severe pressing laminations were observed to arrest the combustion front for TiC samples.

  7. Microstructure evolution and hardness change in ordered Ni3V intermetallic alloy by energetic ion irradiation

    NASA Astrophysics Data System (ADS)

    Hashimoto, A.; Kaneno, Y.; Semboshi, S.; Yoshizaki, H.; Saitoh, Y.; Okamoto, Y.; Iwase, A.

    2014-11-01

    Ni3V bulk intermetallic compounds with ordered D022 structure were irradiated with 16 MeV Au ions at room temperature. The irradiation induced phase transformation was examined by means of the transmission electron microscope (TEM), the extended X-ray absorption fine structure measurement (EXAFS) and the X-ray diffraction (XRD). We also measured the Vickers hardness for unirradiated and irradiated specimens. The TEM observation shows that by the Au irradiation, the lamellar microstructures and the super lattice spot in diffraction pattern for the unirradiated specimen disappeared. This TEM result as well as the result of XRD and EXAFS measurements means that the intrinsic D022 structure of Ni3V changes into the A1 (fcc) structure which is the lattice structure just below the melting point in the thermal equilibrium phase diagram. The lattice structure change from D022 to A1 (fcc) accompanies a remarkable decrease in Vickers microhardness. The change in crystal structure was discussed in terms of the thermal spike and the sequential atomic displacements induced by the energetic heavy ion irradiation.

  8. Polyanionic hydrides from polar intermetallics AeE2 (Ae = Ca, Sr, Ba; E = Al, Ga, In).

    PubMed

    Björling, Thomas; Noréus, Dag; Häussermann, Ulrich

    2006-01-25

    The hydrogenation behavior of the polar intermetallic systems AeE2 (Ae = Ca, Sr, Ba; E = Al, Ga, In) has been investigated systematically and afforded the new hydrides SrGa2H2 and BaGa2H2. The structure of these hydrides was characterized by X-ray powder diffraction and neutron diffraction of the corresponding deuterides. Both compounds are isostructural to previously discovered SrAl2H2 (space group P3m1, Z = 1, SrGa2H2/D2: a = 4.4010(4)/4.3932(8) A, c = 4.7109(4)/4.699(1) A; BaGa2H2/D2: a = 4.5334(6)/4.5286(5) A, c = 4.9069(9)/4.8991(9) A). The three hydrides SrAl2H2, SrGa2H2, and BaGa2H2 decompose at around 300 degrees C at atmospheric pressure. First-principles electronic structure calculations reveal that H is unambiguously part of a two-dimensional polyanion [E2H2]2- in which each E atom is tetrahedrally coordinated by three additional E atoms and H. The compounds AeE2H2 are classified as polyanionic hydrides. The peculiar feature of polyanionic hydrides is the incorporation of H in a polymeric anion where it acts as a terminating ligand. Polyanionic hydrides provide unprecedented arrangements with both E-E and E-H bonds. The hydrogenation of AeE2 to AeE2H2 takes place at low reaction temperatures (around 200 degrees C), which suggests that the polyanion of the polar intermetallics ([E2]2-) is employed as precursor. PMID:16417371

  9. PILOT STUDY ON INTERNATIONAL EXCHANGE ON DIOXINS AND RELATED COMPOUNDS - SCIENTIFIC BASIS FOR THE DEVELOPMENT OF THE INTERNATIONAL METHOD OF RISK ASSESSMENT FOR COMPLEX MIXTURE OF DIOXINS AND RELATED COMPOUNDS

    EPA Science Inventory

    The Pilot Study on International Information Exchange on Dioxins and Related Compounds was initiated to apply the cooperative efforts of several nations to address issues associated with PCDDs, PCDFs, and related compounds. he three-year study was conducted under the CCMS of NATO...

  10. Peripheral SH-functionalisation of carbosilane dendrimers including the synthesis of the model compound dimethylbis(propanethiol)silane and their interaction with rhodium complexes.

    PubMed

    Camerano, José A; Casado, Miguel A; Ciriano, Miguel A; Tejel, Cristina; Oro, Luis A

    2005-09-21

    Treatment of the allyl-containing compounds Me2Si(CH2CHCH2)2 and MeSi(CH2CHCH2)3 with thioacetic acid in the presence of AIBN gave Me2Si[(CH2)3SC(O)CH3]2 and MeSi[(CH2)3SC(O)CH3]3, respectively, which were reduced with LiAlH4 to the dithiols Me2Si[(CH2)3SH]2(3) and MeSi[(CH2)3SH]3(4). This protocol was applied to the first and second generations of the doubly and triply-branched carbosilane allyl dendrimers, Si[(CH2)3SiMe(CH2CHCH2)2]4(G(1)allyl-8), Si[(CH2)3SiMe{(CH2)3SiMe(CH2CHCH2)2}2]4(G(2)allyl-16), Si[(CH2)3Si(CH2CHCH2)3]4(G(1)allyl-12), and Si[(CH2)3Si{(CH2)3Si(CH2CHCH2)3}3]4(G(2)allyl-36) to give the corresponding SH functionalised surface dendrimers Si[(CH2)3SiMe(CH2CH2CH2SH)2]4(G(1)SH-8), G(2)SH-16, G(1)SH-12, and G(2)SH-36. Reactions of 3 with [M(acac)(diolefin)](M = Rh, Ir; diolefin = 1,5-cyclooctadiene, 2,5-norbornadiene) gave the compounds of the type [M2(mu-Me2Si[(CH2)3S]2)(diolefin)2]n. These diolefin complexes are octanuclear (n= 4) in solution while the complex [Rh2(mu-Me2Si[(CH2)3S]2)(cod)2]n(5) is tetranuclear in the solid state. The structure of 5, solved by X-ray diffraction methods, consists of a 20-membered metallomacrocycle formed by two dimethylbis(propylthiolate)silane moieties bridging four fragments Rh(cod) in a mu2 fashion through the sulfur atoms. Treatment of [Rh(acac)(CO)2] with 3 gave [Rh2(mu-Me2Si[(CH2)3S]2)(CO)4]n, which is a mixture of tetra (n= 2) and octanuclear (n= 4) complexes in a 2 : 1 ratio in solution, while the related complex [Rh2(mu-Me2Si[(CH2)3S]2)(CO)2(PPh3)2]2 is tetranuclear. Reactions of [Rh(acac)(L-L)](L-L = cod, (CO)2, (CO)(PPh3)) with 4 and the dendrimers G(1)SH-8, G(2)SH-16, and G(1)SH-12, gave microcrystalline solids of formulae [Rh3(MeSi[(CH2)3S]3)(L-L)3]n, [Si[(CH2)3SiMe{(CH2)3SRh(cod)}2]4]n([G(1)Rh(cod)-8]n), [Si[(CH2)3Si{(CH2)3SRh(cod)}3]4]n([G(1)Rh(cod)-12]n), etc., which presumably are tridimensional coordination polymers. PMID:16127505

  11. JOURNAL DE PHYSIQUE Colloque C5, supplment au n 5, Tome 40, Mai 1979, page C5-286 Hydrogen storage properties and characteristics of rare earth compounds

    E-print Network

    Paris-Sud XI, Université de

    storage properties and characteristics of rare earth compounds C. E. Lundin Denver Research Institute. -- The characteristics of rare earth intermetallic compounds that absorb sufficient hydrogen to be of interest for energy. Industrial participation is beginning to emerge and shows good potential for expansion. The rare earth

  12. Increased Survivorship and Altered Cytokine Profile from Treatment of Influenza A H1N1-Infected Mice with Ekybion: A Drug Complex of Natural Extracts and Inorganic Compounds

    PubMed Central

    Lupfer, Christopher; Besnouin, Didier; Tepper, Samuel E.; Maselko, Maciej; Patton, Kristin M.; Pastey, Manoj

    2011-01-01

    Ekybion is a drug complex of 16 natural extracts and inorganic compounds designed to treat a variety of respiratory pathogens of bacterial and viral origin. It is licensed throughout Europe for the treatment of respiratory tract infections from equine parainfluenza type 3 and equine herpes virus type 1 in equine stables. The purpose of this paper was to test the efficacy of Ekybion on a well-developed animal model of influenza A infection and determine a mode of action. Experiments were performed with Balb/c mice infected with a lethal dose of influenza A/PR/8/34 H1N1 virus and treated with nebulized Ekybion every 8?h in a time-dependant or dose-dependant fashion. These experiments showed that mice treated prior to infection with Ekybion had a higher survival rates (~46%) compared with untreated animals (~0%). Paradoxically, these mice showed no significant difference in lung virus titer or weight loss. There was, however, a decrease in the level of GM-CSF, IL-6, and G-CSF cytokines in the lungs of Ekybion-treated, infected mice. It is possible that decreases in proinflammatory cytokines may have contributed to increased survivorship in Ekybion-treated influenza-infected mice. PMID:20981272

  13. Compound inheritance of a low-frequency regulatory SNP and a rare null mutation in exon-junction complex subunit RBM8A causes TAR syndrome.

    PubMed

    Albers, Cornelis A; Paul, Dirk S; Schulze, Harald; Freson, Kathleen; Stephens, Jonathan C; Smethurst, Peter A; Jolley, Jennifer D; Cvejic, Ana; Kostadima, Myrto; Bertone, Paul; Breuning, Martijn H; Debili, Najet; Deloukas, Panos; Favier, Rémi; Fiedler, Janine; Hobbs, Catherine M; Huang, Ni; Hurles, Matthew E; Kiddle, Graham; Krapels, Ingrid; Nurden, Paquita; Ruivenkamp, Claudia A L; Sambrook, Jennifer G; Smith, Kenneth; Stemple, Derek L; Strauss, Gabriele; Thys, Chantal; van Geet, Chris; Newbury-Ecob, Ruth; Ouwehand, Willem H; Ghevaert, Cedric

    2012-04-01

    The exon-junction complex (EJC) performs essential RNA processing tasks. Here, we describe the first human disorder, thrombocytopenia with absent radii (TAR), caused by deficiency in one of the four EJC subunits. Compound inheritance of a rare null allele and one of two low-frequency SNPs in the regulatory regions of RBM8A, encoding the Y14 subunit of EJC, causes TAR. We found that this inheritance mechanism explained 53 of 55 cases (P < 5 × 10(-228)) of the rare congenital malformation syndrome. Of the 53 cases with this inheritance pattern, 51 carried a submicroscopic deletion of 1q21.1 that has previously been associated with TAR, and two carried a truncation or frameshift null mutation in RBM8A. We show that the two regulatory SNPs result in diminished RBM8A transcription in vitro and that Y14 expression is reduced in platelets from individuals with TAR. Our data implicate Y14 insufficiency and, presumably, an EJC defect as the cause of TAR syndrome. PMID:22366785

  14. Enhanced Fenton-like degradation of refractory organic compounds by surface complex formation of LaFeO3 and H2O2.

    PubMed

    Nie, Yulun; Zhang, Lili; Li, Yu-You; Hu, Chun

    2015-08-30

    Nanoscale LaFeO3 was prepared via sol-gel method and characterized by XRD, FTIR and N2 adsorption/desorption experiment. The results indicated that, LaFeO3 had a typical perovskite structure with a BET area of 8.5m(2)/g. LaFeO3 exhibited excellent Fenton activity and stability for the degradation of pharmaceuticals and herbicides in water, as demonstrated with sulfamethoxazole, phenazone, phenytoin, acyclovir and 2,4-dichlorophenoxyacetic acid, 2-chlorophenol. Among them, sulfamethoxazole (SMX) could be completely removed in LaFeO3-H2O2 system after reaction for 120min at neutral pH. Based on the ATR-FTIR analysis, the surface complex of LaFeO3 and H2O2 was formed, which was important and essential for the enhanced Fenton reaction by accelerating the cycle of Fe(3+)/Fe(2+). Hence, more OH and O2(-)/HO2(-) were then produced in LaFeO3-H2O2 system, resulting in more efficient removal of refractory organic compounds. Based on the surface interaction of LaFeO3 and H2O2, a heterogeneous Fenton reaction mechanism was proposed. PMID:25867592

  15. Preparation and high intensity heavy ion irradiation tests of intermetallic 243Am/Pd targets

    NASA Astrophysics Data System (ADS)

    Usoltsev, I.; Eichler, R.; Vostokin, G. K.; Sabel'nikov, A. V.; Aksenov, N. V.; Albin, Y. V.; Bozhikov, G. A.; Chepigin, V. I.; Dmitriev, S. N.; Lebedev, V. Ya.; Malyshev, O. N.; Petrushkin, O. V.; Piguet, D.; Starodub, G. Ya.; Svirikhin, A. I.; Türler, A.; Yeremin, A. V.

    2014-01-01

    Previously reported preparation method for Pd-based intermetallic targets (Usoltsev, et al., 2012) [1] has been successfully applied for producing two stationary 243Am/Pd targets. Both targets have been irradiated at the U-400 cyclotron at Flerov Laboratory of Nuclear Reactions Dubna (Russian Federation) using high intensity beams (up to 0.83 ?Apart) of 48Ca18+. Alpha-particle spectroscopy and light microscopy allowed for a comprehensive characterization of the intermetallic targets before and after irradiation. A natNd/Pd intermetallic target and a solely electroplated 243Am/Ti target were similarly investigated for comparison.

  16. Combustion synthesis and mechanical properties of dense NiTi-TiC intermetallic-ceramic composites

    Microsoft Academic Search

    Douglas E. Burkes; Guglielmo Gottoli; John J. Moore; Hu Chun Yi

    2006-01-01

    Combustion synthesis (SHS) coupled with a quasi-isostatic densification step was employed to produce dense NiTi-TiC composites.\\u000a The synthesis and characterization of five composites are presented, including ceramic-intermetallic (?50 pct ceramic) composites\\u000a and intermetallic-ceramic (?50 pct intermetallic) composites. Particle size, X-ray diffraction (XRD), and scanning electron\\u000a microscopy (SEM) analysis was conducted to characterize the microstructure of the composites. Refractory TiC and

  17. The stabilization effect of substituted atoms and magnetism for intermetallic compounds YFe12-xCrx

    NASA Astrophysics Data System (ADS)

    Ma, Huan-Feng; Huang, Zheng; Chen, Bo; Qiang, Wei-Rong; Pan, Min

    2009-05-01

    Based on density functional theory, using the scheme of the linearized augmented plane wave and the improved local orbital (APW+lo), this paper analyses and calculates the lattice parameters, formation energy and magnetism of the rare-earth permanent magnetic materials YFe12-xCrx (x = 0 ~ 5). The stabilization effect and the possible positions of the substituted atom Cr are analysed. Magnetic moments for the system and the atoms are obtained.

  18. Oxidation behavior of intermetallic compounds based on Ti-Al system

    SciTech Connect

    Tomasi, A. [Centro Materiali e Biofisica Medica, Trento (Italy); Gialanella, S.; Orsini, P.G. [Univ. di Trento (Italy). Dipt. di Ingegneria dei Materiali; Nazmy, M. [ABB Power Generation Ltd., Baden (Switzerland)

    1995-07-01

    In this study the authors present some results regarding phase and surface stability, with particular reference to the oxidation, of Ti alloys based on the {gamma}-TiAl phase. They investigated the stability of the metallic phases with TG and DSC methods, according to the temperature range over which the relevant transformations do occur. These tests were particularly useful to select times and temperatures for precipitation hardening treatments and also to evaluate the oxidation resistance. The isothermal oxidation kinetics were followed with a thermobalance (TG) for time up to 25 hours and, for longer treatments, they put the samples in a furnace and measured their weight changes at fixed time intervals. The microstructure of the oxide scale was investigated with scanning electron microscopy and energy dispersion X-ray analysis and mapping. The identification of the crystalline phases was carried out with X-ray diffraction analysis. The obtained results afford clear information on the predominant phenomena assisting the observed oxidation kinetics and give indications on the operating conditions suitable for these materials.

  19. Synthesis and characterization of patterned surfaces and catalytically relevant binary nanocrystalline intermetallic compounds

    E-print Network

    Cable, Robert E.

    2009-05-15

    PtSn2 ? PtSn ? Pt3Sn. Our conversion chemistry occurs in solution at temperatures below 300 °C and within 1 hour, highlighting the high reactivity of our nanocrystalline materials compared to the bulk. Some evidence of the generality for this process...

  20. MERLINERLIN a versatile optimization environment applied to the design of metallic alloys and intermetallic compounds

    E-print Network

    Lagaris, Isaac

    .M. Polatoglou d a Department of Materials Science and Technology, University of Ioannina, P.O. Box 1186, Gr 45110 Ioannina, Greece b Computer Science Department, University of Ioannina, P.O. Box 1186, Gr 45110 Ioannina, Greece c Physics Department, University of Ioannina, P.O. Box 1186, Gr 45110 Ioannina, Greece d